Improved Scotch Yoke Engine or Pump

Field of Invention

This disclosure relates to scotch yoke engines and pumps. More particularly this disclosure relates to means by which the reciprocating mass of the piston and yoke assembly may be guided along the cylinder axis. And this disclosure relates to means by which the mass of a piston assembly of a scotch yoke engine or pump when reciprocated may be counter balanced around the main axis of the crankshaft by counterweight mass of the crankshaft in conjunction with a second reciprocatable mass reciprocated by the same crankshaft. The Prior Art

It is known in the prior art scotch yoke engine or pump to guide the piston along the cylinder axis by the use of elongate guide means which are not the cylinder wall nor the piston skirt. The elongate guide means including a guide member formed with or attached to the piston and, another guide member is attached to the block of the engine or pump by way of fastener means and locator pin means so that its guide surface/s is or are located in a particular orientation relative to the cylinder axis.

As outlined above it is known to provide a piston with at least one elongate second guide means elongate along an axis extending parallel to the cylinder axis and to have the second guide means adapted for engagement with another guide means being a third guide means which is attached to a block of the scotch yoke engine or pump so that the piston is thereby constrained for reciprocal motion along the cylinder axis and prevented from rotation around an axis extending parallel to the main axis of a crankshaft, the piston including a first guide means, other wise known as a yoke adapted for engagement with a connecting means rotatably mounted on the big end bearing means of the crankshaft. An example of state of play in the prior art may be seen in patent application PCT/AU/2000/00281 which discloses a scotch yoke engine or pump which includes a piston having first guide means elongate along an axis extending substantially perpendicular relative to the cylinder axis and adapted for engagement with connecting means adapted to be rotatably mounted on the big end bearing means of a crankshaft, the crankshaft has a main axis around which it rotates and the big end bearing means is centered on a big end bearing axis which is offset from the main axis and parallel thereto. The cylinder axis extends along a plane which is perpendicular to the main axis. The connecting means adapted to orbit the main axis during crankshaft rotation and the first guide means adapted to constrain the connecting means to

reciprocating motion along the first guide means during crankshaft rotation. The piston further including second guide means elongate along an axis extending parallel to the cylinder axis and adapted to engage third guide means formed with or attached to a block, the engagement of the second guide means with the third guide means constraining the piston to reciprocate along the cylinder axis and to prevent rotation of the piston around an axis parallel to the main axis. The piston has a cross sectional area of its crown perpendicular to the cylinder axis and a projection of this cross sectional area in a direction along the cylinder axis towards the crankshaft defines a volume in which the engagement of the second guide means with the third guide means takes place. The third guide means as stated above is formed on or is mounted to the block by attachment means being pivot pin means or bolts or other fastener means. Though the above system may be theoretically possible in practice it presents the manufacturer with an unworkable proposition in that the methodologies which must be conformed with lay outside the capability of high speed production lines because the use locator pin means requires that the third guide means is first positioned correctly then together with the block a set of drillings must be performed to receive locator pin means to align the third guide means into a correct orientation relative the cylinder axis and the main axis and then the third guide means is fastened to the block by fastener means. A drawback of the above approach is that it is a time consuming and laborious task for the manufacturer and if the third guide means must be replaced during the life of the engine or pump the task of doing so may be beyond the capability of the repairer to accomplish as the repairer must in effect replicate the alignment procedures adopted by the original manufacturer and drill a fresh set of locator holes in the third guide means and block and provide new pins for the new holes so that the third guide means may be fastened into a correct angular position on the block relative to the cylinder axis and the crankshaft main axis.

Another factor which has led to problems in the prior art is the difficulty associated with balancing a single cylinder of a scotch yoke engine or pump on the crankshaft. Some prior art practitioners have tried to balance a single piston on a crankshaft by means of a dummy piston arrangement. The prior art arrangements take up a large amount of space which is a particularly burdensome factor in the field of engines and pumps.

Disclosure of Invention We hereby incorporate into this document, in its entirety, for use and reference herein, international patent filing PCT/AU/2000/00281.

Throughout the Disclosure of Invention contained herein the like numbers mean alike things. There are small variations to the various embodiments, related

disclosures and inventive aspects wbich can be easily made but these should not in any way be seen to limit the scope or inventiveness of the embodiments, related disclosures or inventive aspects disclosed herein, any improvements which might be made therefore should be viewed as shop floor type improvements. We have invented means and ways of equipping a crankcase or block (hereinafter referred to as a "block") for a scotch yoke engine or pump having second guide means in engagement with third guide means for guiding the yoke portion of a piston assembly as it reciprocates along the cylinder axis. What we have discovered is that we can form in the block at least one structure which may be fashioned by machine means into a land which is adapted to be mounted to by a prefabricated bearing structure. The land extends inline, that is, parallel to the cylinder axis and is preferably L or Vee shaped such that a prefabricated guide bearing structure may be pulled tight into or onto the corner thereof formed by the land means. Accordingly the present invention provides a new form of attachment system and methods of performing same of the third guide means to the block which substantially overcomes the short comings of the prior art. The present invention (herein after called "the invention" or "our invention"), provides a land means which when viewed parallel to the cylinder axis has a surface which conforms to an arcuate profile in end view, alternatively the land means may include surfaces which conform to a V shape profile in end view. The profile as seen in the view sited above in effect forms a cornering land means like a Vee block. The land means surface/s, that is at least those surfaces or that surface onto which the third guide means is to be fastened, extend parallel to the cylinder axis. The land means surface/s determine the angular orientation of the third guide means relative to the cylinder axis and the main axis of the crankshaft. The third guide means is adapted to include at least one surface which corresponds to the surfia.ce/s of the land means. The third guide means guide surfaces are aligned so that they extend in a direction parallel to the land means surface/s onto which the third guide means is mounted or to be mounted. Fastener means which are preferably releasable fastener means may then used to secure the third guide means to the land means. The idea being to prefabricate the third guide means such its guide surfaces are aligned such they extend in a direction parallel to the surface/s of the third guide means which are to be mounted onto the land means of the block. The Vee land is elongate along an axis which extends substantially parallel to the cylinder axis.

The engine or pump has a cylinder having a cylinder axis extending perpendicular relative to the main axis of a crankshaft. The cylinder has a first end and a second end, the first end being further away from the main axis than is the second end of the cylinder. The cylinder has a cylinder walL When looking along the cylinder

axis the Vee land is located within a projection of the cylinder wall, the projection is in the direction of the main axis. The Vee land has a first end and a second end, the first end of the Vee land is located further away from the main axis than is the second end of the Vee land. The first end of the Vee land is located closer to the first end of the cylinder than is the second end of the Vee land. The land structure is preferably a portion or member of the block.

The invention is suitable for use in all forms of scotch yoke engines or pumps which include a piston assembly having second guide means adapted for engagement with the third guide means of the invention. The piston assembly includes the yoke structure which houses the first guide means. In the prior art the yoke is considered a part or member of the piston as together they are the reciprocating mass.

The Vee land means of the invention may be formed by any suitable machining technique including but not limited to broach tool means, rotating cutting tool means, end mill means, wire cutting machine means. Oil gallery means may be provided in the third guide means to allow oil to pass through the body of the third guide means to the guide bearing surface/s of the third guide means such the engagement of the third guide means with the second guide means may be pressure fed with lubricant. If the block is cast, preferably the basic shape of the Vee land is formed during the casting process and a suitable machining process or set of processes are then conducted to dress the surface so as it can then perform its function as an aligning means and land means for the third guide means. Preferably there are two Vee lands formed for each cylinder of the block so that there is provided two second guide means for each piston and cylinder of the engine or pump.

In this disclosure we show a number of non limiting variants of the profile shape of the land means surface/s when viewed in end view along an axis which is parallel to the cylinder axis. In a first broad embodiment of the invention the land means is a female Vee shape which includes two surfaces, a first planar surface extending parallel a first plane which is substantially perpendicular to the main axis of the crankshaft, and a second surface aligned parallel to a second plane which extends substantially parallel to the main axis of the crankshaft. It is called a female Vee land means because the third guide means is nested into the planar surfaces forming the Vee. The third guide means in end view parallel to the cylinder axis includes a Vee shaped back planar surface arrangement which is of male type and it is adapted to be nested into the Vee surfaces forming the land means which is female. The surface arrangement of the back of the third guide means includes a first planar surface aligned parallel to a plane which extends

parallel to the first plane, and a second surface aligned parallel to the second plane. The surfaces of the back of the third guide means are adapted to be engaged by the surfaces of the female Vee formed on the block to thereby ensure the angular orientation of the third guide means relative to both the cylinder axis and also the main axis of the crankshaft. Fastener means are used to fasten the third guide means into the Vee land so that it is pulled into the corner formed by the Vee. Preferably the fastener means extends along an axis which is aligned to a bisector or substantially parallel to a bisector of the included angle of the Vee land. In yet another broad embodiment of the invention the land means is a female Vee shape which includes two surfaces, a first planar surface extending parallel a first plane which is transverse in a first direction to the main axis of the crankshaft, and a second surface which aligned parallel to a second plane which is transverse in a second direction to the main axis of the crankshaft. It is called a female Vee land means because the third guide means is nested into the surfaces forming the Vee. The third guide means in end view parallel to the cylinder axis includes a Vee shaped back surface arrangement which is of male type and it is adapted to be nested into the Vee surfaces forming the land means which is female. The surface arrangement of the back of the third guide means includes a first planar surface aligned parallel to a plane which extends parallel to the first plane, and a second surface aligned parallel to the second plane. The surfaces of the back of the third guide means are adapted to engage those of the female Vee land formed on the block to thereby ensure the angular orientation of the third guide means relative to both the cylinder axis and also the main axis of the crankshaft. Preferably the first plane is at 90 degrees to the second plane but other angles may be utilized if desired. Fastener means are used to fasten the third guide means into the female Vee land so that it is pulled into the corner formed by the female Vee. Preferably the fastener means extends along an axis which is aligned to a bisector or substantially parallel to a bisector of the included angle of the Vee land. In still another embodiment of the invention the land means is a male Vee shape which includes two surfaces, a first planar surface extending parallel a first plane which is substantially perpendicular to the main axis of the crankshaft, and a second planar surface which extends parallel to a second plane which extends substantially parallel to the main axis of the crankshaft. The third guide means in end view parallel to the cylinder axis includes a Vee shaped back surface arrangement which is of female type and it is adapted to be nested over the Vee land surfaces forming the land means which is male. The surface arrangement of the back of the third guide means includes a first planar surface aligned parallel to a plane which extends parallel to the first plane, and a second surface aligned

parallel to the second plane. The surfaces of the back of the third guide means are adapted to be engaged by the surfaces of the male Vee formed on the block to thereby ensure the angular orientation of the third guide means relative to both the cylinder axis and also the main axis of the crankshaft. Fastener means are used to fasten the third guide means onto the male Vee land so that the third guide means is pulled onto the corner formed by the male Vee. Preferably the fastener means extends along an axis which is aligned to a bisector or substantially parallel to a bisector of the included angle of the male Vee land.

In still yet another broad embodiment of the invention the land means is a male Vee shape which includes two surfaces, a first planar surface extending parallel a first plane which is transverse in a first direction to the main axis of the crankshaft, and a second surface which aligned parallel to a second plane which is transverse in a second direction to the main axis of the crankshaft. The third guide means in end view parallel to the cylinder axis includes a female Vee shaped back surface arrangement which is adapted to be mounted over the Vee surfaces forming the land means which is male. The surface arrangement of the back of the third guide means includes a first planar surface aligned parallel to a plane which extends parallel to the first plane, and a second surface aligned to the second plane. The surfaces of the back of the third guide means are adapted to engage those of the male Vee land formed on the block to thereby ensure the angular orientation of the third guide means relative to both the cylinder axis and also the main axis of the crankshaft. Preferably the first plane is at 90 degrees to the second plane but other angles may be utilized if desired. Fastener means are used to fasten the third guide means onto the male Vee land so that the third guide means is pulled onto the corner formed by the male Vee. Preferably the fastener means extends along an axis which is aligned to a bisector or substantially parallel to a bisector of the included angle of the male Vee land.

We have also found that a third guide means may best be fastened to the land means of the invention with threaded fastener means, though the invention is not limited to such fasteners means as any suitable fastener means may be used as desired including but not limited to rivet means, or other suitable form of clamp position means. It is preferable that the fastener means is a threaded bolt means which passes through the structure of the land means from the back side of the land structure, the back side being that side of the land structure located opposite to the cornered point of the Vee land. If the fastener means is a threaded member it is preferable the elongate axis of it extends along plane which is perpendicular to the cylinder axis.

A fifth broad embodiment of the invention provides two Vee land means for a cylinder, a first Vee land for a first side of the cylinder, and a second Vee land for the second opposite of the cylinder. The first side of the cylinder being located to a first side of a first plane extending perpendicular to the main axis and co-parallel to the cylinder axis, and the second side of the cylinder located to a second side of the first plane.

A yet again another broad embodiment of the invention provides two Vee land means for a cylinder, and a first fastener means for a first side of the engine and a second fastener means for the second opposite side of the engine. The first side of the engine being located to a first side of a second plane extending parallel to the main axis and co-parallel to the cylinder axis, and the second side of the engine located to a second side of the second plane. The first fastener means adapted to pull a first third guide means into engagement with a first land means located on a first side of a cylinder, and the second fastener means adapted to pull a second third guide means into engagement with a second land means located on the opposite side of the cylinder. The first fastener means and the second fastener means each having an axis and which are substantially parallel to each other though extending in spaced relation to each other. The first fastener means axis and the second fastener means axis extending parallel to a plane which is perpendicular to the cylinder axis.

In a broader embodiment of the invention provides two Vee land means for a cylinder, and a first fastener means for a first side of the engine and a second fastener means for the second opposite side of the engine. The first side of the engine being located to a first side of a second plane extending parallel to the main axis and co-parallel to the cylinder axis, and the second side of the engine located to a second side of the second plane. The first fastener means adapted to pull a first third guide means into engagement with a first land means located on a first side of a cylinder, and the second fastener means adapted to pull a second third guide means into engagement with a second land means located on the opposite side of the cylinder. The first fastener means and the second fastener means each having an axis and are not parallel to each other in a first direction but are both substantially parallel to a plane which is perpendicular to the cylinder axis.

An very broad embodiment of the invention provides two Vee land means for a cylinder, and a first fastener means for a first side of the engine and a second fastener means for the first side of the engine. The first side of the engine being located to a first side of a second plane extending parallel to the main axis and co- parallel to the cylinder axis, and the second side of the engine located to a second side of the second plane. The first fastener means adapted to pull a first third

guide means into engagement with a first land means located on a first side of a cylinder, and the second fastener means adapted to pull a second third guide means into engagement with a second land means located on the opposite side of the cylinder. The first fastener means and the second fastener means each having 5 an axis and are not parallel to each other in a first direction but are both parallel to a plane which is perpendicular to the cylinder axis.

In a related broad disclosure of invention provides a preferred tool machine system for fashioning the land means surface/s. The tool machine system includes: broach tool means having cutter surfaces adapted to fashion at least one i o surface of a land means associated with a cylinder, and the broach tool means being adapted to be selectively displaceable along an axis extending substantially parallel to the cylinder axis or co-parallel to the cylinder axis; selectively operable alignment means for aligning the block, its land structure, main axis and cylinder axis relative to the broach tool means. Preferably the alignment means are

15 alignment cone means and each of the alignment cone means being adapted to be mounted on shaft means and preferably hydraulically actuated in at least one direction along their respective axis of motion, the axis of motion being parallel to the main axis of the crankshaft. The broach tool means adapted to fashion the surface/s of at least one land means associated with a cylinder but it is preferred

20 that it is adapted to fashion the surface/s of at two land means associated with a cylinder.

In another related broad disclosure of invention provides another preferred machine tool means for fashioning the land means surface/s which includes a

25 rotatable cutter means being preferably end mill means, the rotatable cutter means having an axis of rotation around which the cutting surface/s of the rotatable cutter means is adapted to revolve and there is also shown provided drill tool means for drilling a hole through the block and land structure in order that a fastener may pull a third guide means onto the finished surface arrangement of the land means,

30 the drill tool means having an axis or rotation which is aligned along a bisector or parallel to a bisector of the included angle of the surface arrangement of the Vee land means and the axis of rotation preferably aligned to a plane extending substantially perpendicular to the cylinder axis.

This disclosure also teaches how a single cylinder of an engine or pump may be 5 balance on the crankshaft, more particularly we teach a new way to balance a single cylinder engine or pump using scotch yoke means. The piston may be connected to a crankshaft by either a conventional type connecting rod arrangement of by a connecting means being in engagement with a first guide

means of the piston assembly. The aspect of invention provides a second scotch yoke arrangement to balance the mass of a first piston arrangement. The aspect of invention provides a crankshaft having a main axis, the crankshaft having a first big end bearing means at a first distance from the main axis, and having a second big end bearing means at a second lesser distance from the main axis. The new system we have invented for the balancing of a single piston in an engine or pump takes up considerably less space than what would be the case if one were to follow the teachings of the prior art, it there fore substantially overcomes a significant draw back of the prior art. The aspect of invention takes to basic form. A first form has the first big end bearing means and the second big end bearing means on the same side of the main axis. A second form has the first big end bearing means on a first side of the main axis and has a second big end bearing means on a second side of the main axis. It is preferable that in both forms the first big end bearing means axis and the second big end bearing means axes intersect a line which intersects the main axis but this need not be so as it is possible to achieve a substantial balance of the piston mass with the first big end bearing means axis intersecting a first line which is radial to the main axis and to have to second big end bearing means axis intersected a second line which is radial to the main axis and separated from the first line around the main axis by a small angle.

We have found that we can substantially balance the mass of a single piston reciprocating in a cylinder and connected to a crankshaft by a connecting rod or a scotch yoke arrangement by the inclusion on the crankshaft of a second big end bearing means having a lessor throw than the first big end bearing means by mounting for rotation on the second big end bearing means a connecting means and having the connecting means adapted for engagement with a first guide means of a second reciprocatable mass which is greater than the mass of the piston. The mass reciprocated by the second big end bearing means is greater than the mass of the piston to compensate for the lower reciprocating speed and inertia of the second reciprocatable mass relative to the mass of the piston. It is preferably that the second reciprocating mass is reciprocated along an axis which is at substantially 90 degrees to the cylinder axis but we also show herein a embodiment of an aspect of the invention wherein the axis along which the second reciprocating mass reciprocates is in a direction which is substantially opposite to the direction of the axis the piston reciprocates along, relative to the main axis, the cylinder axis extending on a first side of the main axis and the second axis extending on the opposite second side of the main axis; the cylinder axis may intersect the main axis and the second axis may intersect the main axis; the

cylinder axis may be parallel to a line which is radial to the main axis, the second axis may be parallel to a line which is radial to the main axis, as desired.

A first broad aspect of invention of the disclosure provides a scotch yoke engine or pump with a crankshaft having a main axis and a first big end bearing means having a first big end bearing means axis located at a first distance from the main axis, the crankshaft further including a second big end bearing means having a second big end bearing means axis located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line intersecting the main axis as each other. A cylinder is provided having a cylinder axis extending along a plane which is perpendicular to the main axis. A first sliding connecting means is rotatably mounted on the first big end bearing means, and a second sliding connecting means is rotatably mounted on the second big end bearing means. A piston assembly comprising a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis. The piston assembly including first guide means elongate along an axis extending substantially perpendicular relative to the cylinder axis and parallel to a plane which is perpendicular to the main axis. The first guide means is adapted for engagement with the first sliding connecting means to thereby constrain the first sliding connecting means to reciprocating motion along the first guide means during crankshaft rotation around the main axis. A second reciprocatable mass is provided which is adapted to be reciprocated along an axis which is at 90 degrees to the cylinder axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a second first guide means elongate along an axis extending substantially perpendicular to the axis along which the second reciprocatable mass is adapted to be reciprocated. The piston assembly including a first second guide means elongate along a first second guide means axis which extends along a plane which is perpendicular to the main axis and which is parallel to the cylinder axis. The first second guide means is adapted for engagement with a first third guide means. The engagement of the first third guide means with the first second guide means being such the piston assembly is prevented from rotation around an axis parallel to the main axis and the piston assembly is constrained thereby to reciprocal motion along the cylinder axis. The second reciprocatable mass including a second second guide means elongate along a second second guide means axis which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second second guide means is adapted for engagement with a

second third guide means. The engagement of the second third guide means with the second second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The crankshaft including counted weight mass means having a centre of mass opposite on the same radial line as the first big end bearing means axis and the second big end bearing means axis but is located on the opposite side of the main axis to them. The second reciprocatable mass being more massy than the first reciprocatable mass and the massy-ness of the counter weight mass being such that the second reciprocatable mass and the first reciprocatable mass are at least partially counterbalanced by the counterbalance mass of the counterweight means. Preferably the first reciprocatable mass and the second reciprocatable mass are substantially counterbalanced by the counter balance mass of the counterbalance means of the crankshaft. Preferably the cylinder axis intersects the main axis or is parallel to a line which intersects the main axis. In an alternative arrangement the first big end bearing means axis is located on a first radial line which intersects the main axis and the second big end bearing means axis is located on a second radial line which intersects the main axis. The first radial line being at small angle relative to the second radial line around the main axis and he counter weight means counter balance mass partially counterbalances the first reciprocatable mass and the second reciprocatable mass.

A second broad aspect of an invention of the disclosure provides a scotch yoke engine or pump with a crankshaft having a main axis and a first big end bearing means having a first big end bearing means axis located at a first distance from the main axis, the crankshaft further including a second big end bearing means having a second big end bearing means axis located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line intersecting the main axis as each other. A cylinder is provided having a cylinder axis extending along a plane which is perpendicular to the main axis. A connecting rod means big end is rotatably mounted on the first big end bearing means, and a sliding connecting means is rotatably mounted on the second big end bearing means. A piston assembly comprising a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis. The piston assembly including gudgeon pin means having an axis extending substantially perpendicular relative to the cylinder axis and parallel to the main axis, the gudgeon pin means being pivotably connected to the little end

of the connecting rod means. A second reciprocatable mass is provided which is adapted to be reciprocated along an axis which is at 90 degrees to the cylinder axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a first guide means elongate along an axis extending substantially perpendicular to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second guide means is adapted for engagement with a third guide means. The second reciprocatable mass including a second guide means elongate along a second guide means axis which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second guide means is adapted for engagement with a third guide means. The engagement of the third guide means with the second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The crankshaft including counted weight mass means having a centre of mass opposite to the first big end bearing means axis relative to the main axis but located on the same radial line as the first big end bearing means axis and the second big end bearing means axis is located on. The second reciprocatable mass being more massy than the first reciprocatable mass and the massy-ness of the counter weight mass being such that the second reciprocatable mass and the first reciprocatable mass are at least partially counterbalanced by the counterbalance mass of the counterweight means.

A third broad aspect of invention of the disclosure provides a scotch yoke engine or pump with a crankshaft having a main axis and a first big end bearing means having a first big end bearing means axis located at a first distance from the main axis, the crankshaft further including a second big end bearing means having a second big end bearing means axis located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line intersecting the main axis as each other but being on opposite sides of the main axis to each other. A cylinder is provided having a cylinder axis extending along a plane which is perpendicular to the main axis. A connecting rod means big end is rotatably mounted on the first big end bearing means, and a sliding connecting means is rotatably mounted on the second big end bearing means. A piston assembly comprising a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis. The piston assembly including gudgeon pin means having an axis extending substantially perpendicular

relative to the cylinder axis and parallel to the main axis, the gudgeon pin means being pivotably mounted to the little end of the connecting rod means. A second reciprocatable mass is provided which is adapted to be reciprocated along an axis which is at 180 degrees to the cylinder axis relative to the main axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a first guide means elongate along an axis extending substantially perpendicular to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second guide means is adapted for engagement with a first guide means. The second reciprocatable mass including a second guide means elongate along a second guide means axis which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second guide means is adapted for engagement with a third guide means. The engagement of the third guide means with the second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The second reciprocatable mass being more massy than the first reciprocatable mass such that the second reciprocatable mass and the first reciprocatable mass at least partially counterbalance each other.

Brief Description of the Drawings

Figure 1 is a sectional schematic top plan view.

Figure 2 is a sectional schematic top plan view.

Figure 3 is a sectional schematic top plan view. Figure 4 is a sectional schematic isometric view.

Figure 5 is a sectional schematic top plan view.

Figure 6 is a sectional schematic top plan view.

Figure 7 is a sectional schematic top plan view.

Figure 8 is a schematic sectional side view. Figure 9 is a schematic sectional side view.

Figure 10 is a sectional schematic end view.

Figure 11 is a sectional schematic end view.

Figure 12 is a sectional schematic end view.

Figure 13 is a sectional schematic end view. Figure 14 is a sectional schematic end view.

Detailed Description of the Drawings

In Figure 1 is shown a first broad embodiment of the invention 10. The view is a sectional schematic end view inline with the cylinder axis 1. The invention provides land means 2a, 2b which are of female Vee shape, the land means 2a, 2b each include two land surfaces, land means 2a having a first surface 22a and having a second surface 22b, surface 22a being a first planar surface extending parallel a first plane which is transverse in a first direction to the main axis 3 of a crankshaft (not shown), and its second surface 22b is aligned parallel to a second plane which is transverse in a second direction to the main axis of the crankshaft. It is called a female Vee land means because the third guide means 4a is nested into the surfaces 22a, 22b forming the Vee land 2a. The third guide means 4a in end view parallel to the cylinder axis includes a Vee shaped back surface arrangement which is of male type and it is adapted to be nested into the Vee surfaces forming the land means 2a which is female. The surface arrangement of the back of the third guide means includes a first planar surface 44a aligned parallel to a plane which extends parallel to the first plane, and a second surface 44b aligned parallel to the second plane. The surfaces of the back of the third guide means are adapted to engage those of the female Vee land 2a formed on the block 5 to thereby ensure the angular orientation of the third guide means 2a relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft. Preferably the first plane is at 90 degrees to the second plane but other angles may be utilized if desired. Fastener means 6a are used to fasten the third guide means 4a into the female Vee land 2a so that it is pulled into the corner 20a formed by the female Vee land 2a. Preferably the fastener means 6a extends along an axis 66a which is aligned to a bisector or substantially parallel to a bisector of the included angle of the Vee land 2a. Land means 2b having a first surface 23 a and having a second surface 23b, surface 23a being a first planar surface extending parallel a third plane which is transverse in a third direction to the main axis 3, and its second surface 23b is aligned parallel to a fourth plane which is transverse in a fourth direction to the main axis. In this case land means 2b is like wise a female Vee land means and as can be seen a third guide means 4b is nested into the surfaces 23a, 23b forming the Vee land 2b. The third guide means 4b in end view parallel to the cylinder axis 1 includes a Vee shaped back surface arrangement which is of male type and it is adapted to be nested into the Vee surfaces forming the land means 2b which is female. The surface arrangement of the back of the third guide means 4b includes a first planar surface 45a aligned parallel to a plane

which extends parallel to the third plane, and a second surface 44b aligned parallel to the fourth plane. The surfaces of the back of the third guide means are adapted to engage those of the female Vee land 2b formed on the block 5 to thereby ensure the angular orientation of the third guide means 2b relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft. Preferably the third plane is at 90 degrees to the fourth plane but other angles may be utilized if desired. Fastener means 6b are used to fasten the third guide means 4b into the female Vee land 2b so that it is pulled into the corner 20b formed by the female Vee land 2b. Preferably the fastener means 6b extends along an axis 66b which is aligned to a bisector or substantially parallel to a bisector of the included angle of the Vee land 2b. preferably the fastener axes 66a, 66b are parallel to the main axis 3. One or more fastener means may be used to secure the third guide means of the invention onto the surfaces of a Vee land in any of the embodiments of the invention. $0a,b,c denote guide surfaces of the third guide means 4a and the reader being a man skilled in the art will appreciate this throughout the disclosure herein. The guide surfaces may be planar, rollerized or arcuate as desired. The inner wall of the cylinder 11 is shown projected/overlaid onto the drawing of the land means and third guide means. There is a hole 70a provided through the block 5 wall through which fastener means 6a can pass so as it may be screwed into the back of the third guide means 4a and the fastener may when tightened pull the third guide means back surfaces 44a and 44b into engagement with surfaces 22a, 22b respectively. There is a hole 70b provided through the block 5 wall through which the fastener means 6b can pass so as it may be screwed into, the back of the third guide means 4b and the fastener means may, when tightened, pull the third guide means back surfaces 45a and 45b into engagement with surfaces 23a, 23b respectively. The third guide means 4a, 4b each have at least one threaded hole/recess in their backs to receive and engage with their respective fastener means. The body of the third guide means 4a, 4b may however have through holes through which a fastener may pass and a bolt means or stud passed through said through holes allowing the fastener means to screw into the block or a nut means if desired. The land means surface arrangement extends parallel to the cylinder axis

In Figure 2 is shown a second broad embodiment of the invention 10. The view is a sectional schematic end view inline with the cylinder axis 1. The invention provides land means 2a, 2b which are male Vee in shape. Each Vee land includes two land surfaces, land 2a includes a first planar surface 22a extending parallel a first plane which is substantially perpendicular to the main axis 3 of the crankshaft (not shown), and a second planar surface 22b which extends parallel to a second plane which extends substantially parallel to the main axis of the crankshaft. A

third guide means 4a seen in end view parallel to the cylinder axis 1 includes a Vee shaped back surface arrangement which is of female type and it is adapted to be nested over the Vee land surfaces 22a, 22b forming the land means 2a. The surface arrangement of the back of the third guide means 4a includes a first planar surface 44a aligned parallel to a plane which extends parallel to the first plane, and a second surface 44b aligned parallel to the second plane. The surfaces 44a, 44b of the back of the third guide means 4a are adapted to be engaged by the surfaces of the male Vee land 2a formed on the block 5 to thereby ensure the angular orientation of the third guide means 4a relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft. Fastener means 6a are used to fasten the third guide means 4a onto the male Vee land 2a so that the third guide means is pulled over the corner system formed by the male Vee. Preferably the fastener means 6a extends along an axis 66a which is aligned to a bisector or substantially parallel to a bisector of the included angle of the male Vee land 2a. Land 2b includes a first planar surface 23 a extending parallel a third plane which is substantially perpendicular to the main axis 3 of the crankshaft (not shown), and a second planar surface 23b which extends parallel to a fourth plane which extends substantially parallel to the main axis of the crankshaft. A third guide means 4b seen in end view parallel to the cylinder axis 1 includes a Vee shaped back surface arrangement which is of female type and it is adapted to be nested over the Vee land surfaces 23a, 23b forming the land means 2b. The surface arrangement of the back of the third guide means 4b includes a first planar surface 45a aligned parallel to a plane which extends parallel to the third plane, and a second surface 45b aligned parallel to the fourth plane. The surfaces 45a, 45b of the back of the third guide means 4b are adapted to be engaged by the surfaces of the male Vee land 2b formed on the block 5 to thereby ensure the angular orientation of the third guide means 4b relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft. Fastener means 6b are used to fasten the third guide means 4b onto the male Vee land 2b so that the third guide means is pulled over the corner system formed by the male Vee. Preferably the fastener means 6b extends along an axis 66b which is aligned to a bisector or substantially parallel to a bisector of the included angle of the male Vee land 2b. Fastener means 6a, 6b are provided to pull the third guide means 4a, 4b back surfaces into engagement with the surfaces of their respective Vee lands. Preferably the Vee land 4a surfaces 44a, 44b are aligned on first and second planes which are at 90 degrees to each other.

Preferably the Vee land 4a surfaces 45a, 45b are aligned on third and fourth planes which are at 90 degrees to each other. Preferably the second and fourth planes are parallel to each other, and the first and third planes are parallel to each other. The fastener means shown is a threaded bolt means however it may be a stud or rivet

post or the like. The land means surface arrangement extends parallel to the cylinder axis

In Figure 3 is shown a second broad embodiment of the invention 10. The view is a sectional schematic end view inline with the cylinder axis 1. The invention provides land means 2a, 2b which are male Vee in shape. Each Vee land includes two land surfaces, Vee land 2a includes a first planar surface 22a extending parallel a first plane which is transverse in a first direction to the main axis 3 of the crankshaft (not shown), and a second surface 22b which is aligned parallel to a second plane which is transverse in a second direction to the main axis of the crankshaft. A third guide means 4a is seen in end view parallel to the cylinder axis 1 which includes a female Vee shaped back surface arrangement which is adapted to be mounted over the Vee surfaces forming the land means 2a. The surface arrangement of the back of the third guide means 4a includes a first planar surface 44a aligned parallel to a plane which extends parallel to the first plane, and a second surface 44b aligned parallel to the second plane. The surfaces 44a, 44b of the back of the third guide means 4a are adapted to engage those of the male Vee land 2a formed on the block 5 of the engine or pump 10 to thereby ensure the angular orientation of the third guide means 4a relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft. Preferably the first plane is at 90 degrees to the second plane but other angles may be utilized if desired. Fastener means 6a are used to fasten the third guide means 4a onto the male Vee land 2a so that the third guide means is pulled onto/over the corner formed by the male Vee 2a. Preferably the fastener means 6a extends along an axis 66a which is aligned to a bisector or substantially parallel to a bisector of the included angle of the male Vee land 2a. Vee land 2b includes a first planar surface 23a extending parallel a third plane which is transverse in a third direction to the main axis 3 of the crankshaft (not shown), and a second surface 23b which is aligned parallel to a fourth plane which is transverse in a fourth direction to the main axis of the crankshaft. A third guide means 4b is seen in end view parallel to the cylinder axis 1 which includes a female Vee shaped back surface arrangement which is adapted to be mounted over the Vee surfaces forming the land means 2b. The surface arrangement of the back of the third guide means 4b includes a first planar surface 45a aligned parallel to a plane which extends parallel to the third plane, and a second surface 45b aligned parallel to the fourth plane. The surfaces 45a, 45b of the back of the third guide means 4b are adapted to engage those of the male Vee land 2b formed on the block 5 of the engine or pump 10 to thereby ensure the angular orientation of the third guide means 4b relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft. Preferably the third plane is at 90 degrees to the fourth plane but other angles may be utilized if

desired. Fastener means 6b are used to fasten the third guide means 4b onto the male Vee land 2b surfaces such that the third guide means 4b is pulled onto/over the corner formed by the male Vee 2b. Preferably the fastener means 6b extends along an axis 66b which is aligned to a bisector or substantially parallel to a bisector of the included angle of the male Vee land 2b and parallel to the main axis. The land means surface arrangement extends parallel to the cylinder axis

We have also found that a third guide means may best be fastened to the land means of the invention with threaded fastener means, though the invention is not limited to such fasteners means as any suitable fastener means may be used as desired including but not limited to rivet means, or other suitable form of clamp position means. It is preferable that the fastener means is a threaded bolt means which passes through the structure of the land means from the back side of the land structure, the back side being that side of the land structure located opposite to the cornered point of the Vee land. If the fastener means is a threaded member it is preferable the elongate axis of it extends along plane which is perpendicular to the cylinder axis. It can be seen there is provided two Vee land means 2a, 2b for a cylinder 11, a first Vee land 2a for a first side of the cylinder, and a second Vee land 2b for the second opposite of the cylinder. The first side of the cylinder being located to a first side of a first dividing plane 8 extending perpendicular to the main axis 3 and co-parallel to the cylinder axis 1, and the second side of the cylinder located to a second side of the first dividing plane 8. It can therefore be seen the fastener means 6a is adapted to tighten the third guide means 4a to a first side of the engine or pump and, the fastener means tightens the third guide means to a second side of the engine or pump. Figure 4 shows a perspective schematic side view of a fourth broad embodiment of the invention 10 which shows the relative location of the lands means 2a, 2b in relation to the main axis 3 of a crankshaft (not shown) and the top 110 of the cylinder 11. It can be seen that the cylinder has an axis 1 which is perpendicular relative to the main axis. It can be seen that the lands means 2a, 2b lays between the top of the cylinder and the main axis. The land means surface arrangement extends parallel to the cylinder axis

Figure 5 shows a fifth broad embodiment of the invention 10 which is a sectional schematic top plan view seen parallel to the cylinder axes Ia, Ib, Ic, of a multi- cylindered engine or pump. The engine includes two Vee land means for each respective cylinder, and a first fastener means for a first side of the engine and a second fastener means for the second opposite side of the engine for each respective Vee land of a respective cylinder. The first side of the engine being located to a first side of a dividing plane 8 which extends parallel to the main axis

and co-parallel to the cylinder axes and is indicated by arrow A, and the second side of the engine located to a second side of the dividing plane and is indicated by arrow B. A first fastener means is provided for each respective cylinder and is adapted to pull a respective first third guide means for a respective cylinder into engagement with a respective first land means located on a first side of the engine or pump, and there is provided a second fastener means for each respective cylinder which is adapted to pull a respective second third guide means into engagement with a respective second land means for each cylinder on the second side of the engine or pump. The first fastener means and the second fastener means for each respective cylinders' land means each having a respective axis and are preferably substantially parallel to each other though extending in spaced relation to each other. The first fastener means axis and the second fastener means axis for each respective cylinder extending parallel to a plane which is perpendicular to the cylinder axes Ia, Ib, Ic. It can be seen that each land means and third guide means back side surface arrangement includes two surfaces, a first respective surface aligned to a parallel with the main axis and a second surface aligned to a line perpendicular to the main axis. It is a multi-cylindered engine or pump and in this case for illustration purposes it is a three cylinder engine or pump having a first cylinder l la having a first cylinder axis Ia, a second cylinder lib having a second cylinder axis Ib, a third cylinder 1 Ic having a third cylinder axis Ic. When viewing Figure 5 we advise the reader to consider Figure 2 and the detailed description pertaining to same as this Figure 5 is a multi-cylindered version of it in many respects, especially in relation to the orientation of the land surfaces and the back side surface arrangement surfaces of the third guide means. Therefore the detailed description pertaining to Figure 2 and pertaining to the above cited features, namely the surfaces of the back side of the third guide means and the surfaces of the land means, should be used as a map for the detailing of the description of Figure 5. The land means surface arrangement extends parallel to the cylinder axis Figure 6 shows a sixth broad embodiment of the invention 10 and the view of it is a sectional schematic top plan view of the engine or pump looking along the cylinder axes. The engine or pump is a multi-cylindered engine or pump which includes two Vee land means for each respective cylinder, a fastener means is provided for each third guide means and each third guide means is secured to its respective land means on the same side of the engine or pump. A dividing plane 8 is shown which is parallel to the main axis and co-parallel to each to the cylinder axis. When viewing Figure 6 we advise the reader to consider Figure 2 and the detailed description pertaining to same as this Figure 6 is a multi-cylindered version of it in many respects, especially in relation to the orientation of the land

surfaces and the back side surface arrangement surfaces of the third guide means. Therefore the detailed description pertaining to Figure 2 and pertaining to the above cited features, namely the surfaces of the back side of the third guide means and the surfaces of the land means, should be used as a map for the detailing of the description of Figure 6. The land means surface arrangement extends parallel to the cylinder axis

In Figure 7 is shown a seventh broad embodiment of the invention 10. The view is a sectional schematic end view inline with the cylinder axis 1. The invention provides land means 2, which is male in shape and includes an arcuate land surface 22. A third guide means 4 is seen in end view parallel to the cylinder axis 1 which includes a female back surface arrangement which includes an arcuate female surface 44 which is adapted to be mounted over the arcuate surface forming the land means 2. The surfaces 44 of the back of the third guide means 4 being adapted to engage the of the male land surface 22 formed on the block 5 of the engine or pump 10 to thereby ensure the angular orientation of the third guide means 4 relative to both the cylinder axis 1 and also the main axis 3 of the crankshaft.. Fastener means 6 is provided to fasten the third guide means 4 onto the male land 2 so that the third guide means 4 is pulled onto/over the arc formed by the male land 2. Preferably the fastener means 6 extends along an axis 66 which is aligned to a plane which is perpendicular to the cylinder axis. The land means surface arrangement extends parallel to the cylinder axis. It will be appreciated by the man skilled in the art that the arcute land surface may be a female land surface and that the back side surface arrangement of the third guide means may be an arcuate male surface which is simply an opposite arrangement of what we have shown in this Figure 7, accordingly this alternative is disclosed herein.

In Figure 8 a first related broad disclosure of invention is shown in a schematic sectional side view, the view looking through the main axis and through the cylinder axis such the main axis is parallel to page and the cylinder axis is parallel to the page. Figure 8 shows a preferred tool machine system 100 for fashioning land means surface/s of the engine or pump of Figure 1 through to 7. The tool machine system includes broach tool means 140 having cutter surfaces 141 adapted to fashion at least one surface of a land means 2a, 2b associated with a cylinder 11, and the broach tool means being adapted to be selectively displaceable along an axis 14 extending substantially parallel to the cylinder axis 1 ; selectively operable alignment means for aligning the block, its land structure 2, main axis 3 and cylinder axis relative to the broach tool means axis of motion 14. Preferably the alignment means are alignment cone means 16a, 16b, 16c and each of the alignment cone means being adapted to be mounted on shaft means and

preferably hydraulically actuated in at least one direction along their respective axis of motion, the axis of motion of the cone means 16b, 16c being parallel to the main axis 3 of a main bearing tunnel for the engine or pump. The broach tool means adapted to fashion the surface/s of at least one land means 2a or 2b

5 associated with a cylinder 11 but it is preferred that it is adapted to fashion the surface/s of two land means 2q, 2b associated with a cylinder. The alignment cone means 16a includes is centered on an axis which is co-parallel to the broach tool means axis of motion 14, and the alignment cone 16a includes a coned surface 166a which is inclined towards the broach tool means axis of motion and l o the main axis and is adapted to engage the inner top surface 200 of the cylinder wall 11 to thereby center the cylinder on the axis of motion of the broach tool means. The alignment cone means 16b, 16c are mounted for motion along an axis 33 which is perpendicular to the broach tool means axis of motion and the alignment cone means 16b, 16ceach include a respective coned surface means

15 166b, 166c which are inclined towards each other. Alignment cone surface means 166b is adapted to engage the main bearing tunnel 180a from a first direction along the axis 3 it may move along and alignment cone surface means 166c is adapted to engage the main bearing tunnel 180b from a second direction along the axis the alignment cone means 16b may move along, alignment cone surface

20 means 166b and 166c to engage the main bearing tunnel by moving towards each other along axis 3 and thereby centre the bearing tunnel means 180a and 180b along the axis they may move along. The main bearing tunnel includes two tunnel portions, a first portion 180a located at a first distance in a first direction from a plane which is co-parallel to the cylinder axis and is perpendicular to the tunnel

25 axis 3 and, a second portion 180b which is located at a second location along the tunnel axis 3 in a second opposite direction to the first direction to where the first portion is located. The alignment cone means 16b coned surface 166b engages the furthest away from the plane circular surface 190a of the first potion 180b and the alignment cone means 16c coned surface 166c engages the furthest away from

30 the plane circular surface 190b of the second portion of the tunnel. It can be seen therefore that the combination of the engagements of the alignment cone means 16a, 16b, 16c coned surfaces with the block in this way can pull or force the block into an alignment in relation to the cylinder axis and the main bearing tunnel axis of the block. The broach tool means has an axis of motion 14 and with the block

35 forced into an orientation relative to its axis of motion and in relation to the main axis it can then work along its axis of motion to cut the land means surfaces so that they are parallel to the cylinder axis and perpendicular relative to the main bearing tunnel axis axis.

In Figure 9 a second related broad disclosure of invention is shown in a schematic sectional side view, the view looking through the main axis and through the cylinder axis such the main axis is parallel to page and the cylinder axis is parallel to the page. Figure 9 shows another preferred tool machine system 100 for fashioning land means surface/s of the engine or pump of Figure 1 through to 7 which includes a rotatable cutter means 300 being preferably end mill means, the rotatable cutter means having an axis of rotation 300 which the cutting surface/s of the rotatable cutter means is adapted to revolve and is perpendicular relative to the cylinder axis 1, and there is also shown provided drill tool means 450 for drilling a hole 70 the block 5 and land structure 2 in order that a fastener may pull a third guide means (not shown) onto the finished surface arrangement of the land means, the drill tool means having an axis of rotation 400 which is aligned substantially along a bisector or parallel to a bisector of the included angle of the surface arrangement of the land means 2 and the axis of rotation preferably aligned to a plane extending substantially perpendicular to the cylinder axis 1.

This disclosure also teaches how a single cylinder of an engine or pump may be balanced on a crankshaft, more particularly we teach a new way to balance a single piston reciprocating in a cylinder of an engine or pump using scotch yoke means. The piston may be connected to a crankshaft by either a conventional type connecting rod arrangement of by a connecting means being in engagement with a first guide means of the piston assembly. The aspect of invention provides a second scotch yoke arrangement to balance the mass of a first piston arrangement. The aspect of invention provides a crankshaft having a main axis, the crankshaft having a first big end bearing means at a first distance from the main axis, and having a second big end bearing means at a second lesser distance from the main axis.

The disclosures of invention pertaining to Figures 1 through to 6 is not necessarily excluded from the aspects of invention we now discuss in a detailed description of the following drawings and description pertaining to same and it is envisaged that the improvements shown in the following drawings and detailed in relation to the following drawings may be incorporated into the engine or pump detailed in Figures 1 through to 6 if desired.

The aspects of invention takes two basic forms. A first form has the first big end bearing means axis and the second big end bearing means axis on the same side of the main axis. A second form has the first big end bearing means axis on a first side of the main axis and has a second big end bearing means axis on a second side of the main axis. It is preferable that in both forms the first big end bearing means axis and the second big end bearing means axes intersect a line which

intersects the main axis but this need not be so as it is possible to achieve a substantial balance of the piston mass with the first big end bearing means axis intersecting a first line which is radial to the main axis and to have to second big end bearing means axis intersect a second line which is radial to the main axis and separated from the first line around the main axis by an angle being a small angle.

We have found that we can substantially balance the mass of a single piston reciprocating in a cylinder and connected to a crankshaft by a connecting rod or a scotch yoke arrangement by the inclusion on the crankshaft of a second big end bearing means having a lessor throw than the first big end bearing means by mounting for rotation on the second big end bearing means a connecting means and having the connecting means adapted for engagement with a first guide means of a second reciprocatable mass which is greater than the mass of the piston. The mass reciprocated by the second big end bearing means is greater than the mass of the piston to compensate for the lower reciprocating speed and inertia of the second reciprocatable mass relative to the mass of the piston. It is preferably that the second reciprocating mass is reciprocated along an axis which is at substantially 90 degrees to the cylinder axis but we also show herein a embodiment of an aspect of the invention wherein the axis along which the second reciprocating mass reciprocates is in a direction which is substantially opposite to the direction of the axis the piston reciprocates along, relative to the main axis, the cylinder axis extending on a first side of the main axis and the second axis extending on the opposite second side of the main axis; the cylinder axis may intersect the main axis and the second axis may intersect the main axis; the cylinder axis may be parallel to a line which is radial to the main axis, the second axis may be parallel to a line which is radial to the main axis, as desired.

Figure 10 shows first broad aspect of invention of the disclosure which provides a scotch yoke engine or pump 10 with a crankshaft 33 having a main axis 3 and a first big end bearing means 34 having a first big end bearing means axis 35 located at a first distance from the main axis, the crankshaft further including a second big end bearing means 36 having a second big end bearing means axis 37 located at a second lessor distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line A intersecting the main axis as each other. A cylinder 11 is provided having a cylinder axis 1 extending along a plane which is perpendicular to the main axis. A first sliding connecting means 50 is rotatably mounted on the first big end bearing means, and a second sliding connecting means 51 is rotatably mounted on the second big end bearing means. A piston assembly being a first reciprocatable mass is provided which is mounted

for reciprocating motion in the cylinder along the cylinder axis. The piston assembly including first guide means 61, 62 elongate along an axis 63 extending substantially perpendicular relative to the cylinder axis and parallel to a plane which is perpendicular to the main axis. The first guide means is adapted for engagement with the first sliding connecting means to thereby constrain the first sliding connecting means to reciprocating motion along the first guide means during crankshaft rotation around the main axis. A second reciprocatable mass 90 is provided which is adapted to be reciprocated along an axis 94 which is at 90 degrees to the cylinder axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a second first guide means 91, 92 elongate along an axis 93 extending substantially perpendicular to the axis along which the second reciprocatable mass is adapted to be reciprocated. The piston assembly including a first second guide means 63 elongate along a first second guide means axis 64 which extends along a plane which is perpendicular to the main axis and which is parallel to the cylinder axis. The first second guide means is adapted for engagement with a first third guide means 66. The engagement of the first third guide means with the first second guide means being such the piston assembly is prevented from rotation around an axis parallel to the main axis and the piston assembly is constrained thereby to reciprocal motion along the cylinder axis. The second reciprocatable mass including second second guide means 95 elongate along a second second guide means axis 94 which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second second guide means is adapted for engagement with second third guide means 95. The engagement of the second third guide means with the second second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The crankshaft including counted weight mass means 38 having a centre of mass on the same radial line as the first big end bearing means axis and the second big end bearing means axis but is located on the opposite side of the main axis to them. The second reciprocatable mass being more massy than the first reciprocatable mass and the massy-ness of the counter weight mass being such that the second reciprocatable mass and the first reciprocatable mass are at least partially counterbalanced by the counterbalance mass of the counterweight means. Preferably the first reciprocatable mass and the second reciprocatable mass are substantially counterbalanced by the counter balance mass of the counterbalance means of the crankshaft. Preferably the cylinder axis intersects the main axis or is parallel to a line which intersects the main axis. In an alternative arrangement the

first big end bearing means axis is located on a first radial line which intersects the main axis and the second big end bearing means axis is located on a second radial line which intersects the main axis. The first radial line being at small angle relative to the second radial line around the main axis and he counter weight means counter balance mass partially counterbalances the first reciprocatable mass and the second reciprocatable mass. The piston assembly is shown in a exploded view so that is can be seen that there may be included a flying cross arrangement 600 between the end face of the shank 601 of the yoke structure of the piston assembly 60 and the piston base 602, however this feature is only a preferrment. The view of the engine or pump is a sectional schematic end view looking along the main axis. The second big end bearing means diameter can be formed, if desired, to be large enough that the main bearing journal means 33 lays within a projection of it, the projection of the circumference of the big end bearing means being inline with the main axis, however in this Figure we have shown the second big end bearing means being of a smaller diameter. The second reciprocatable mass being compensatingly more massy than the first reciprocatable mass so that the mass of the counterbalance means need in effect only counterbalance a mass equivalent to the first reciprocatable mass to substantially balance the two reciprocatable masses on the crankshaft. Because the mass of the second reciprocatable mass is compensatingly greater than the mass of the first reciprocatable mass the two masses combined are equivalent to a single mass the equivalent of the first reciprocatable mass moving in a circle, however it is envisaged that it may be an elipse.

Figure 11 shows second broad aspect of invention of the disclosure which provides a scotch yoke engine or pump 10 with a crankshaft having a main axis and a first big end bearing means 34 having a first big end bearing means axis 35 located at a first distance from the main axis 3 of a crankshaft 33 having main bearing journal means 33a the crankshaft further including a second big end bearing means 36 having a second big end bearing means axis 37 located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line A intersecting the main axis as each other. A cylinder 11 is provided having a cylinder axis 1 extending along a plane which is perpendicular to the main axis. A connecting rod means 50 having a big end 55 is rotatably mounted on the first big end bearing means, and a sliding connecting means 51 is rotatably mounted on the second big end bearing means. A piston assembly 60 being a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis, (the first

reciprocatable mass may include a portion of the connecting rod 50 mass as is common knowledge in the field). The piston assembly including gudgeon pin means 52 having a gudgeon pin axis 54 extending substantially perpendicular relative to the cylinder axis and parallel to the main axis, the gudgeon pin means being pivotably connected to the little end 56 of the connecting rod means. A second reciprocatable mass 90 is provided which is adapted to be reciprocated along an axis 94 which is at 90 degrees to the cylinder axis and is aligned along a plane which perpendicular to the main axis. It is a preferπnent that the axis 94 is exactly perpendicular relative to the cylinder axis but it may be at an angle other than 90 degrees, the alternative angle being less than 15 degrees from perpendicular to the cylinder axis. The second reciprocatable mass including a first guide means 91, 92 elongate along an axis 93 extending substantially perpendicular to the axis 1 along which the second reciprocatable mass is adapted to be reciprocated. The second guide means is adapted for engagement with a third guide means. The second reciprocatable mass including second guide means 96 elongate along second guide means axis 94a which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second guide means 96 is adapted for engagement with a third guide means 95. The engagement of the third guide means with the second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciproca]table mass is adapted to be reciprocated along. The crankshaft including counterweight mass means 38 having a centre of mass opposite to the first big end bearing means axis relative to the main axis but located on the same radial line as the first big end bearing means axis and the second big end bearing means axis is located on. The second reciprocatable mass being compensatingly more massy than the first reciprocatable mass so that the mass of the counterbalance means need in effect only counterbalance a mass equivalent to the first reciprocatable mass to substantially balance the two reciprocatable masses on the crankshaft Because the mass of the second reciprocatable mass is compensatingly greater than the mass of the first reciprocatable mass the two masses combined are equivalent to a single mass the equivalent of the first reciprocatable mass moving in a circle, however it is envisaged that it may be an elipse. The view is a sectional schematic end view looking along the main axis.

Figure 12 shows a third broad aspect of invention of the disclosure which provides a scotch yoke engine or pump 10 with a crankshaft 33 having a main axis 3 and a first big end bearing means 34 having a first big end bearing means axis 135

located at a first distance from the main axis, the crankshaft further including a second big end bearing means 36 having a second big end bearing means axis 37 located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line intersecting the main axis as each other but being on opposite sides of the main axis to each other. A cylinder 11 is provided having a cylinder axis 1 extending along a plane which is perpendicular to the main axis. A connecting rod means 50 having a big end 55 is rotatably mounted on the first big end bearing means, and a sliding connecting means 51 is rotatably mounted on the second big end bearing means. A piston assembly 60 being a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis, (portion of the mass of the connecting rod means may be included in the calculation of the first reciprocatable mass as is the case in the field of the art). The piston assembly including gudgeon pin means 52 having an axis 54 extending substantially perpendicular relative to the cylinder axis and parallel to the main axis, the gudgeon pin means being pivotably mounted to the little end 56 of the connecting rod means. A second reciprocatable mass 90 is provided which is adapted to be reciprocated along an axis 94 which is at 180 degrees to the cylinder axis relative to the main axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a first guide means 91, 92 elongate along an axis 93 extending substantially perpendicular to the axis 1 along which the second reciprocatable mass is adapted to be reciprocated. The second guide means 96 is adapted for engagement with a first guide means 95. The second reciprocatable mass including a second guide means 96 elongate along a second guide means axis 94a which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second guide means is adapted for engagement with a third guide means 95. The engagement of the third guide means with the second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The second reciprocatable mass being compensatingly more massy than the first reciprocatable mass such that the second reciprocatable mass and the first reciprocatable mass at least partially counterbalance each other. The view is a sectional schematic end view looking along the main axis.

Figure 13 shows a fourth broad aspect of an invention of the disclosure which provides a scotch yoke engine or pump 10 with a crankshaft 33 having a main axis 3 and a first big end bearing means 34 having a first big end bearing means axis 35 located at a first distance from the main axis, the crankshaft further including a second big end bearing means 36 having a second big end bearing means axis 37 located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line intersecting the main axis as each other but being on opposite sides of the main axis to each other. A cylinder 11 is provided having a cylinder axis 1 extending along a plane which is perpendicular to the main axis. A first connecting means 50 is rotatably mounted on the first big end bearing means, and a second connecting means 51 is rotatably mounted on the second big end bearing means. A piston assembly 60 being a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis. The piston assembly including a first first guide means 61, 62 elongate along a first first guide means axis 63 and adapted to engage the first connecting means 50 to constrain the first connecting means to reciprocal motion long the first first guide means during crankshaft rotation. A second reciprocatable mass 90 is provided which is adapted to be reciprocated along an axis 94 which is at 180 degrees to the cylinder axis relative to the main axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a second first guide means 91, 92 elongate along an axis 93 extending substantially perpendicular to the axis 94 along which the second reciprocatable mass is adapted to be reciprocated. The second reciprocatable mass including second second guide means 96 adapted for engagement with second first guide means 95. The second reciprocatable mass second guide means 96 elongate along a second guide means axis 94a which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second second guide means is adapted for engagement with second third guide means 95. The engagement of the second third guide means with the second second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The second reciprocatable mass being compensatingly more massy than the first reciprocatable mass such that the second reciprocatable mass and the first reciprocatable mass at least partially counterbalance each other. The view is a sectional schematic end view looking along the main axis. Preferably the second

reciprocatable mass and the first reciprocatable mass are of masses sufficient to completely balance each other across the main axis.

Figure 14 shows a fourth broad version of an invention of the disclosure which provides a scotch yoke engine or pump 10 with a crankshaft 33 having a main axis 3 and a first big end bearing means 34 having a first big end bearing means axis 35 located at a first distance from the main axis, the crankshaft further including a second big end bearing means 36 having a second big end bearing means axis 37 located at a second distance from the main axis. The first big end bearing means axis being further away from the main axis than is the second big end bearing means axis. The first big end bearing means axis and the second big end bearing means axis being on the same radial line intersecting the main axis as each other and being on the same side of the main axis as each other. A cylinder 11 is provided having a cylinder axis 1 extending along a plane which is perpendicular to the main axis 3. A first connecting means 50 is rotatably mounted on the first big end bearing means, and a second connecting means 51 is rotatably mounted on the second big end bearing means 36. A piston assembly 60 being a first reciprocatable mass is provided which is mounted for reciprocating motion in the cylinder along the cylinder axis. The piston assembly including a first first guide means 61, 62 elongate along a first first guide means axis 63 and adapted to engage the first connecting means 50 to constrain the first connecting means to reciprocal motion long the first first guide means during crankshaft rotation. A second reciprocatable mass 90 is provided which is adapted to be reciprocated along an axis 94 which is at 90 degrees to the cylinder axis relative to the main axis and is aligned along a plane which perpendicular to the main axis. The second reciprocatable mass including a second first guide means 91, 92 elongate along an axis 93 extending substantially perpendicular to the axis 94 along which the second reciprocatable mass is adapted to be reciprocated. The second reciprocatable mass including second second guide means 96 adapted for engagement with second first guide means 95. The second reciprocatable mass second guide means 96 elongate along a second guide means axis 94a which extends along a plane which is perpendicular to the main axis and which is parallel to the axis along which the second reciprocatable mass is adapted to be reciprocated. The second second guide means is adapted for engagement with second third guide means 95. The engagement of the second third guide means with the second second guide means being such the second reciprocatable mass is prevented from rotation around an axis parallel to the main axis and the second reciprocatable mass is constrained thereby to reciprocal motion along the axis which the second reciprocatable mass is adapted to be reciprocated along. The view is a sectional schematic end view looking along the main axis. The

crankshaft including counterweight mass means 38 having a centre of mass opposite to the first big end bearing means axis relative to the main axis but located on the same radial line as the first big end bearing means axis and the second big end bearing means axis is located on. The second reciprocatable mass being compensatingly more massy than the first reciprocatable mass so that me mass of the counterbalance means need in effect only counterbalance a mass equivalent to the first reciprocatable mass to substantially balance the two reciprocatable masses on the crankshaft. Because the mass of the second reciprocatable mass is compensatingly greater than the mass of the first reciprocatable mass the two masses combined are equivalent to a single mass the equivalent of the first reciprocatable mass moving in a circle, however it is envisaged that it may be an elipse. The view is a sectional schematic end view looking along the main axis. It can be seen that the main bearing is located within a projection of the second big end bearing means circumference. In the drawing we have included a connecting rod means in dashed line to represent the fact that the same arrangement can be used with a connecting rod means connecting the piston assembly to the first big end bearing means if desired, (if this is the case then a portion of the connecting rod mass will have to be added to the calculation of the mass representing the first reciprocatable mass, and the device wont exactly balance but will substantially balance the firs and second reciprocating masses). NB: The Figure 14 shows the second big end bearing means axis on the same side of the main axis as is the first big end bearing means but the skilled man in the art will readily inderstand that the second big end bearing axis may be located on the opposite siude of the main axis to the location of the first big end bearing mean axis if desired but that it is the compensatory mass of the second reciprocatable member rather than the counterweight mass means on the crankshaft which counterbalances the first reciprocating mass across the crankshaft main axis.

Statement of Industrial Applicability and Commercial Utility

The invention has industrial applicability and commercial utility in the field of scotch yoke engines and pumps.