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Title:
MECHANISM FOR CONVERTING A RECIPROCATING MOVEMENT INTO A ROTATIONAL MOVEMENT AND VICE VERSA, AND DEVICE COMPRISING SUCH A MECHANISM.
Document Type and Number:
WIPO Patent Application WO/2011/110325
Kind Code:
A2
Abstract:
Mechanism for converting a reciprocating movement into a rotational movement and vice versa, the mechanism comprising at least three wheels (1,2,3) working together, whereby the excentrical rotational axis (1b,1b',1b") of the first wheel (1) reciprocates rectilinearly with respect to the excentrical rotational axis (2b,3b) of the second and third wheels (2,3), whereby the second and third wheels (2,3) are also positively coupled in their rotation via further means (1',2',3',14), and the at least one wheel (1,2,3), which is provided with means for rotatable connection with a rectilinear reciprocating member, is not provided with means for a rotatable connection at the axis through its centre (1a,2a,3a), or at least two wheels are coupled by means of magnetism, so that the wheels can not disengage from each other.

Inventors:
VAALBURG, Jacob (Seoellaan 42, KK Nieuw-Vennep, NL-2152, NL)
Application Number:
EP2011/001126
Publication Date:
September 15, 2011
Filing Date:
March 07, 2011
Export Citation:
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Assignee:
VAALBURG RESEARCH B.V. (Boekweitstraat 10, GL Nieuw-Vennep, NL-2153, NL)
VAALBURG, Jacob (Seoellaan 42, KK Nieuw-Vennep, NL-2152, NL)
International Classes:
F16H21/36; F16H21/30
Foreign References:
DE3232974A11984-03-15
DE4430423A11995-03-02
FR863706A1941-04-08
EP0708274A11996-04-24
US4077267A1978-03-07
FR2443575A11980-07-04
FR2545890A11984-11-16
DE3232974A11984-03-15
DE4430423A11995-03-02
Download PDF:
Claims:
CLAIMS

1. Mechanism for converting a reciprocating movement into a rotational movement and vice versa without a crankshaft, the mechanism comprising at least three wheels (1,2,3) working together,

at least a first wheel (1) with a centre (la) which wheel is rotatable around a first excentrical rotational axis (lb, lb', lb") and at least

second and third wheels (2,3) with respective second and third centres (2a,3a) which wheels are rotatable around respective second and third excentrical rotational axis (2b,3b), whereby the first wheel (1) is arranged with respect to the second and third wheels (2,3) such that during rotation of the wheels (1,2,3) the position of the centres (la,2a,3a) of the wheels with respect to each other stays the same and

the excentrical rotational axis (lb, lb', lb") of the first wheel (1) reciprocates rectilinearly with respect to the excentrical rotational axis (2b,3b) of the second and third wheels (2,3);

the second and third wheels (2,3) being positively coupled in their rotation via the first wheel

(i);

at least one wheel (1,2,3) is provided with means for a rotatable connection with a rectilinear reciprocating member, at a location of a crossing with at least one of its excentrical rotational axis (lb,lb',2b,3b) and the at least one wheel being rotatable around an axis through its centre (la,2a,3a),

characterized in that,

the second and third wheels (2,3) are also positively coupled in their rotation via further means (Γ,2',3',14) ,

and the at least one wheel (1,2,3), which is provided with means for rotatable connection with a rectilinear reciprocating member, is not provided with means for a rotatable connection at the axis through its centre (la,2a,3a).

2. Mechanism for conversion of a reciprocating movement into a rotational movement and vice versa without a crankshaft, the mechanism comprising at least three wheels (1,2,3) working together,

at least a first excentrical wheel (1) with a centre (la) which wheel is rotatable around a first excentrical rotational axis (lb,lb',lb") and at least

second and third wheels (2,3) with respective second and third centres (2a,3a) which wheels are rotatable around respective second and third excentrical rotational axis (2b,3b), whereby the first wheel (1) is arranged with respect to the second and third wheels (2,3) such that during rotation of the wheels (1,2,3) the position of the centres (la,2a,3a) of the wheels with respect to each other stays the same and

the excentrical rotational axis (lb,lb',lb") of the first wheel (1) reciprocates rectilinearly with respect to the excentrical rotational axis (2b,3b) of the second and third wheels (2,3);

the second and third wheels (2,3) being positively coupled in their rotation via the first wheel

(i);

at least one wheel (1,2,3) is provided with means for rotatable connection with a rectilinear reciprocating member at a location of the crossing with at least one of its excentrical rotational axis (lb,2b,3b) and the at least one wheel being rotatable around an axis through its centre (la,2a,3a),

characterized in that,

at least two wheels are coupled by means of magnetism, so that the wheels can not disengage from each other.

3. Mechanism according to claim 1 or 2, characterized in that, several means for rotatable connection with rectilinear reciprocating members are arranged such that at least two means follow perpendicular rectilinear reciprocating movements.

4. Mechanism according to claim 1, characterized in that the further means (Γ,2',3',14) are formed by centrical gear wheels and/or excentrical gearwheels, by hypoid gear wheels, a ring gear, a toothed belt, a chain or a rod.

5. Mechanism according to at least one of the preceding claims, characterized in that the wheels have a toothing, preferably a helical toothing, which is especially symmetrical.

6. Mechanism according to at least one of the preceding claims, characterized in that the

centres (la,2a,3a) of the wheels (1,2,3) stay arranged on a straight line.

7. Device comprising at least one mechanism according to at least one of the preceding claims

1-6.

8,Device, for example an engine, a pump, a compressor or combination thereof, according to claim 7, whereby the rotational axis of the first wheel (lb, lb', lb") or both rotational axis (2b,3b) of the second and third wheels are connected to at least one piston (5,6) preferably via a connecting rod (4), whereby preferably the connecting rod is fixedly mounted to or integral with at least one piston (5,6), whereby the at least one piston is arranged in at least one cylinder (7,8).

9. Device according to claim 8, characterized in that, the connecting rod (4) comprises two open grooves perpendicular to each, the first groove for allowing a shaft to pass through and the second groove for allowing a gear wheel, perpendicularly arranged to the shaft, to pass through.

10. Device according to claim 8 or claim 9, characterized in that the connecting rod and/or the piston have a channel for cooling and/or lubrication.

11. Device according to at least one of claims 8-10, characterized in that the compression ratio is adjustable by varying the position of the bearings of the axis (2b,3b) of the second and third wheels in the chassis of the device (or of the axis (lb) of the first wheel in the chassis, in case this axis has a fixed bearing) with respect to the position of for example the cylinders (7,8).

12. Device according to at least one of claims 8-11, characterized in that the compression ratio is adjustable by varying the distance between the rotational axis of the first wheel (lb, lb', lb") and the side of the at least one piston facing away from the first wheel (or the distance between the rotational axis of the second and third wheel and the side of the at least one piston facing away from these wheels (2,3), when the axis (lb) has a fixed bearing).

13. Device according to at least one of claims 7-12, characterized in that, the second and third wheels are mounted on straight shafts, whereby along their length several second or third wheels (2,3) are arranged preferably with a different angular orientation with respect to each other.

14. Mechanism according to least one of claims 1-6 or the device according to at least one of claims 7-13, characterized in that, it comprises a counter balancing mass at a location X on the at least one wheel which is provided with the means for rotatable connection with a rectilinear reciprocating member, whereby said location X and the location of said means for rotatable connection with a rectilinear reciprocating member are point symmetrical with respect to the centre of the at least one wheel (1,2,3) and at least one counter balancing mass with respect to at least one fixedly rotatable shaft, preferably by means of mass added.on at least one excentrically mounted wheel on that shaft at the side opposite the centre of that at least one wheel and/or by means of reducing mass at the side of the centre of that at least one wheel.

Description:
Mechanism for converting a reciprocating movement into a rotational movement and vice versa, and device comprising such a mechanism.

This invention relates to a mechanism for converting a reciprocating movement into a rotational movement and vice versa, device comprising such a mechanism, method of making and use of such a mechanism or device. Application of such mechanisms is e.g. in

(piston)engines, (piston)pumps, (piston)compressors, (valve)actuators, control and

movements in automated fabrication processes, sawing machines, windscreen wiper drive mechanisms etc., etc.

Although the invention can be used for many applications e.g. as mentioned above, the invention will be described with reference to the application in the field of piston engines. The invention is however in no way limited to this application.

Prior art.

Such mechanisms or devices suitable for piston engines are e.g. known from EP-A-0 708 274. In figure 20 of this document a conventional crank-connecting rod mechanism is shown. A major drawback of this mechanism is that the connecting rod does not move in a straight line but rather in a pendulum like way, thereby introducing extra vibrations and side forces on the cylinder wall. Another drawback is the complicated form of the crankshaft which is therefore relatively expensive to produce.

Furthermore, this document describes a mechanism whereby the connecting rod is attached eccentrically to a gear wheel, the gear wheel being mounted on a crank and turnable in a stationary ring with internal teeth. Although the movement of the connecting rod is rectilinear, it is not easy to install the ring with internal teeth in the engine block. Also the fabrication costs of such a ring are relatively high. Furthermore, a crankshaft is still needed which is complicated to make.

In US-A-4 077 267 several elliptical gear wheels are used, whereby a central elliptical wheel is kept in engagement with four other elliptical wheels (connected to the pistons) by means of connecting links. Also in this embodiment extra vibrations due to the non linear motion but pendulum like movement of these links arise. Furthermore, the fabrication of the elliptical wheels is relatively complicated. In FR-A-2 443 575 a connecting rod connects to a crankshaft to which latter a second crankshaft is connected via eccentrical gear wheels. Here, the connecting rod does not move rectilinearly and a non favorable crankshaft is needed.

In FR-A-2 545 890 a connecting rod connects to a crank between two eccentrically arranged gear wheels with sliding bearings. These gear wheels are engaged with an eccentrical gear wheel having a fixed bearing and are kept into engagement with connecting elements which are formed around the outer circumference of the eccentrical wheels. Apart from the enormous friction that occurs, the connecting elements do not move rectilinearly but like a pendulum and cause beside the connecting rods extra vibrations.

DE-A-3232974 describes a mechanism for converting a reciprocating movement into a rotational movement and vice versa, using at least three gearwheels one of which is freely rotatable around the axis through its centre. One embodiment shows the connection of the wheels to three crankshafts, which are difficult to manufacture.

Another embodiment shows the freely rotatable wheel being provided at its rotational axis through its centre with a difficult to produce crankshaft. The other wheels are coupled in their rotation by further means in the form of a surrounding belt. This belt establishes only a frictional connection between the wheels, which allows for slip of the belt and relative movement of the centres of the wheels with respect to each other, especially when the belt tension is decreasing due to wear, resulting in a malfunctioning of the mechanism.

Finally, DE-A-4430423 describes a similar mechanism using two excentrically rotating gear wheels, only one having a fixed excentrical rotating axis, whereby the wheels are kept engaged by a connecting rod connecting the centres of the wheels. In one example it is described that a third gear wheel can be arranged for guiding the freely rotating wheel (the wheel which has no fixed rotating axis). How this third wheel is kept engaged with the other wheels is not disclosed and it is even recommended not to use three (or more) wheels. Other embodiments show rods with grooves in which pins are guided which result in enormous frictional losses. Always connections are provided at the rotational axis through the centre of the freely rotating wheel resulting in extra friction losses and limitations to connect the reciprocating member at both sides of the freely rotating wheel.

Many mechanisms have the further drawback that the dimensions are relatively large in at least one direction.

Object of the invention The object of the invention is to realize a mechanism and a device for converting a reciprocating movement into a rotational movement and vice versa, such that at least one of the above drawbacks or complications is obviated or reduced.

Solution

These objects are achieved with the mechanisms according to claims 1 and 2.

Especially, when starting from a mechanism according to the prior art as described in DE-A-

4430423 the objects are achieved with the characterising features of claims 1 and 2.

According to a first alternative, the mechanism according to the invention is characterised in that the second and third wheels are also positively coupled by further means; a reliable engagement of all wheels is achieved, whereby the position of the centres of the wheels is kept at all times and disengagement of the second and third wheels from the first wheel is obviated.

Because the further means rotate together with the second and third wheels, the friction in the mechanism is kept to a minimum.

The mechanism according to the invention is further characterised in that the at least one wheel, which is provided with means for a rotatable connection with a rectilinear

reciprocating member, is not provided with means for a rotatable connection at the axis through its centre i.e. not provided at this location with any further bearing or any further shaft for a rotatable connection.

Since in the mechanism according to the invention only means for a rotatable connection are provided at an excentrical rotational axis of the at least one wheel, the frictional losses are lower compared to prior art mechanisms having rotatable connection means both at the axis through the centre and at an excentrical rotational axis of the wheel. Also the mechansim can be produced with less cost, as the means for a rotatable connection at the centre are normally to be made with great precision.

Furthermore, the fact that the mechanism according to the invention has no means for a rotatable connection at the centre of the at least one wheel, is advantageous for balancing the mechanism

In the past the applicant has used in several test models of the mechanism (not publicly available) for the at least one wheel, wheels which were in fact produced for other devices. These wheels were easily available for the applicant and the tooth profile of these wheels was regarded specifically suitable for the mechanism. The wheels had blind holes at the axis through their centres in which roller bearings were press-fitted (as these wheels were normally supported for rotation around the axis through their centres in the other devices). It was believed that the extra mass at the centre the wheels due to the presence of the superfluous rotatable connection means (the roller bearings) would not harm and would even help to balance the mechanism. Later it was found that the contrary is true, and that extra mass at this location only increases the mass of the at least one wheel resulting in bigger counter balancing masses elsewhere in the mechanism, so that the overall weight of the mechanism was substantially increased. Thus such means for a rotatable connection at the axis through the centre of the at least one wheel have to be avoided.

Consequently, since in the mechanism according to the invention there are no means for a rotatable connection at the axis through the centre of the at least one wheel, the balancing masses are smaller and therefore the overall weight of the mechanism is lower compared to prior art mechanisms having rotatable connection means both at the axis through the centre and at an excentrical rotational axis of the wheel.

Also, in the mechansim according to the invention the connection of the reciprocating rod to the wheel can not be hindered anymore by any means for a rotatable connection at the axis through the centre of the wheel. With the absence of any rotatable connection at the centre of the at least one wheel, the connecting rod can advantageously be connected on both sides of the wheel. Also with the absence of any rotatable connection means at the centre of the at least one wheel, the overall width of the wheel is kept to a minimum and the shaft for the rotatable connection at the excentrical axis can be kept short.

According to a second alternative the mechanism according to the invention is characterised in that at least two wheels are coupled by means of magnetism, so that the wheels can not disengage from each other. Thus magnetism is used in order to keep the wheels engaged e.g. the wheels could be magnetised so that they attract each other. Also electro magnetism can be used e.g. electric engines could be arranged to keep the motion of the second and third wheels synchronised at all times, so that these wheels, with the first wheel in between, are kept coupled at all times.

Preferably, several means for rotatable connection with rectilinear reciprocating members are arranged such that at least two means follow perpendicular rectilinear reciprocating movements. With this arrangement balancing of the mechanism connected to reciprocating members becomes very easy.

Preferably, the further means can be formed by centrical and/or excentrical gearwheels or ring gears. Also a chain, a toothed belt, hypoid gear wheels or any other transmission using positive engagement (different from frictional engagement) can be used. Also a simple rod e.g. with holes at its ends rotateably and positively connecting to shaft stubs on e.g. the second and third wheels can be thought of.

In particular the wheels have a toothing which can be helical and preferably is a symmetrical helical toothing, e.g. a fish-bone toothing.

Preferably, the centres of the wheels stay arranged on a straight line during motion. With this arrangement embodiments can have a relatively small height.

The mechanism can be used in all kind of devices.

It can for example be used in a device like an engine, a pump, a compressor or combinations thereof, whereby the rotational axis of the first wheel or both rotational axis of the second and third wheels are connected to at least one piston, possibly via a connecting rod, whereby preferably the connecting rod is fixedly mounted to or integral with the at least one piston, whereby the at least one pistons is arranged in at least one cylinder. Because the pistons do not need to be hingely connected, a complicated hinge connection as used in conventional engines between connecting rod and piston can be obviated. Not only the piston(s) but also the connecting rods do make a pure rectilinear reciprocating movement. Vibrations causing noise and loss of power are herewith strongly reduced or even obviated.

Preferably, the connecting rod comprises two open grooves perpendicular to each, the first groove for allowing a shaft to pass through and the second groove for allowing a gear wheel, perpendicularly arranged to the shaft, to pass through. Preferably the connecting rod has a cylindrical shape whereby the rod can be hollow. Also the connecting rod can be a (hollow) rod with a rectangular cross section. With such shapes and especially when the rods are made of one piece, the connecting rods can be very rigid. These rods are advantageously used when flat constructions are required. Symmetrical connection of these rods on both sides of the at least one wheel or first wheel leads to a proper force transmission between the connecting rod and wheels. Preferably, the device comprises means for cooling and/or lubrication, whereby in particular the reciprocating parts comprised of the connecting rod and/or the piston have a channel for cooling and/or lubrication purposes.

Preferably, the compression ratio is adjustable by varying the position of the rotational axis (and thus the bearings) of the second and third wheels in the chassis of the device (or of the axis of the first wheel in the chassis, in case this axis has a fixed bearing) with respect to the position of for example the cylinders.

Preferably, the compression ratio is adjustable by varying the distance between the rotational axis of the first wheel and the side of the at least one piston facing away from the first wheel or the distance between the rotational axis of the second and third wheel and the side of the at least one piston facing away from these wheels. This can be realized relatively easily, as the reciprocating movement of the connecting rod and piston is purely rectilinear.

Preferably, the second and third wheels are mounted on straight shafts, whereby preferably along their length several second and third wheels are arranged with a different orientation with respect to each other. With this construction it is possible to combine several mechanisms having simple straight shafts and to fabricate embodiments in which vibrations of the mechanisms are balanced or reduced.

By using straight shafts standard bearings can be applied. The bearing rings do not have to be split like the main bearings and big end bearings on the cranks of a crankshaft in a

conventional engine. The use of ball bearings and roller bearings is therefore extremely advantageous. These bearings have as a further advantage, that the efficiency is much higher than conventional hydrodynamic sliding bearings, especially with low temperatures and/or high rotational speeds. Furthermore, the mounting is substantially simplified because the bearings can be simply pushed over the straight shafts.

With the device according to the invention wear and internal friction are reduced to a minimum. The movement and the position of the engagement point of the connecting rod, in particular the eccentrical rotational axis of the first wheel, is dynamically determined. This engagement point, or this eccentrical rotational axis, makes a rectilinear reciprocating movement which is strictly determined by the turning and the position of the second and third wheels. Side forces introduced by the connecting rod on the piston and thus side forces from the piston perpendicular to its rectilinear movement on the cylinder wall as in conventional engines are therefore not present in devices according to the invention.

The pistons will reciprocate purely rectilinearly, and not as in conventional engines, slap against

the cylinder walls due to changing side forces. Since the so called piston slap is not present, the noise produced will be lower.

For mechanisms according to the invention standard gear wheels, preferably with

symmetrical helical teeth, can be used. The helical teeth help to reduce noise. With symmetrical teeth no side forces are introduced by the teeth on the wheels during rotation. Beside the standard gear wheels, simple straight shafts can be used, so that complicated crankshafts are redundant. Also complicated connecting rods and hinge connections of the pistons are not needed. The production costs are therefore substantially reduced.

When standard round gear wheels are used they can have a bearing or shaft arranged at excentrical rotational axis i.e. axis which do not coincide with the centres of the wheels. Such wheels can be easily balanced with respect to their rotational axis for example by adding extra mass on the wheel or by taking away mass at the side of the centre of the wheel.

By correctly balancing the wheels and/or the shafts on which the wheels are mounted vibrations in a mechanism or a device according to the invention can be reduced to a minimum. Further separate balancing shafts as often used in conventional engines are therefore not necessary anymore. With a symmetrical arrangement of the pistons vibrations of the reciprocating mass can also be eliminated. Therefore also the flywheel mass can be minimized.

Mechanisms and devices according to the invention are preferably balanced by mounting a counter balancing mass at a location on the at least one wheel which is provided with the means for rotatable connection with a rectilinear reciprocating member, whereby said location and the location of said means for rotatable connection with a rectilinear

reciprocating member are point symmetrical with respect to the centre of the at least one wheel and by providing at least one counter balancing mass with respect to at least one fixedly rotatable shaft, preferably on at least one excentrically mounted wheel on that shaft at the side opposite of the centre. In stead of or in addition to adding mass, mass can be taken away at the side of the centre of that at least one wheel.

The counter balancing mass on the at least one wheel is equal to the mass of the reciprocating mass, i.e the total mass of the conneting rod and the piston(s) when connected thereto. A mass for balancing which is mounted or added to a wheel or a shaft can be a resultant mass constituted by e.g two masses arranged symmetrically on both sides of that wheel. Such masses could_be mounted on arms on both sides of the wheel, whereby the arms are perpendicularly mounted on the shafts on which the wheels are mounted.

The mechanisms and devices according to the invention have thus minimal vibrations and reduced wear which makes them very suitable for high revolutional speeds.

For all devices having constructions in which the connecting rod reciprocates horizontally, or at least not vertically, it can furthermore be advantageous to balance the connecting rod (with possibly connected piston(s) thereto) around its connecting point to the at least one wheel or first wheel. In case the connecting rod is connected to pistons reciprocating in cylinders, this balancing measure can reduce or completely obviate the side force on the cylinder walls which normally result from gravitational forces on the pistons. Wear of the cylinder walls and piston(rings) is thus further reduced.

Normally, in the device according to the invention the rotational axis of the second and third wheels have a fixed bearing on a fixed chassis, whereas the excentrical rotational axis of the first wheel reciprocates. At the axis of the second and third wheels the rotational input and/or output is arranged. A rectilinear drive or driven element engages the excentrical rotational axis of the first wheel.

Of course, also the excentrical rotational axis of the first wheel can have a bearing on a fixed chassis and the excentrical rotational axis of the second and third wheels can have a bearing on a moveable chassis part that reciprocates with respect to the fixed chassis. In this case a rectilinear drive or driven element engages the movable chassis part with thereon the bearings of the rotational axis of the second and third wheels. The rotational input and /or output is then arranged at the first rotational axis.

The reciprocating part (with one or two wheels) is for efficiency reasons and depending on the circumstances made as light as possible and e.g. made of a relatively light metal, titanium, carbonfiber material or combinations of these materials.

When the wheels have positively engaging teeth there belongs to every position of the wheels only one predetermined position of the pistons, so that the mechanism is kinematically determined.

Slipping of the wheels is then impossible, so that the transmission of high power is possible. Apart from reducing friction losses an object of the invention is also to provide a mechanism which has minimal dimensions in at least one direction. Below, several embodiments of the mechanism according to the invention will be described. In these embodiments the centres of the three wheels are arranged on a straight iign (see e.g. figures l-3e) or the centres of the three wheels are not arranged on a straight line and consequently are arranged to form a triangle (see e.g. figures 3f and 3g).

With the embodiments where the centres of the wheels are arranged on a straight line, extremely flat constructions and constructions with minimal width can be realised. The extremely flat constructions have the centres of the wheels arranged on a horizontal lign and have connecting rods crossing the shafts (see e.g. figure 3c). Here it is prefered to have connecting rods comprising at least two perpendicular grooves.

The constructions with minimal width have the centres of the wheels arranged on a vertical lign, whereby the connecting rod is arranged horizontally. In these cases the connecting rod can have only one groove for allowing the first wheel (or the at least one wheel) to pass through.

With the embodiments where the centres of the wheels are arranged to form a triangle, mechanisms with minimal depth can be realised. Embodiments with minimal depth have their further means (which connect the second and third wheels) arranged in substantially the same plane as the first, second and third wheels (see e.g. figures 3f and 3g), so that the depth in the direction of the shafts is kept to a minimum.

Especially the embodiments with the centres of the wheels arranged to form a triangle can favourably be used to find a compromise to achieve minimal dimensions in several or all directions. Also then connecting rods comprising at least two perpendicular grooves or only one groove can be used.

The invention will now be explained with several examples of embodiments according to the invention and will be described by using the following figures: figures la-lc, mechanism according to the invention

figure 2a, coupling of the wheels (2,3) by means of the first wheel (1) and the wheels (Γ,2',3') figure 2b, coupling of the wheels (2,3) and wheels (2',3') by means of rods S

figure 3a, mechanism with a piston for e.g. Straight engines

figure 3b, two mechanisms coupled for V-engines

figure 3c, mechanism with two pistons for boxer engines figure 3d, two mechanisms coupled with two pistons

figure 3e, mechanism with piston reciprocating under different angles

figure 3f, mechanism with two wheels rotateably connected to a connecting rod with two pistons

figure 3g, mechanism with four pistons and four wheels

figure 3h, mechanism with three pistons and a ring gear

figure 3i, mechanism with two set of pistons reciprocating perpendicularly, using a ring gear figure 4, several mechanisms with two pistons arranged next to each other (8 cylinder boxer) figure 5, device according to the invention with variable compression ratio and cooling and/or lubrication.

In figures la-lc a mechanism according to the invention is shown, comprising a first wheel (1) arranged between a second wheel (2) and a third wheel (3). The wheels have a radius r and at the eccentrical rotational axis (lb,2b,3b) of the wheels shafts or bearings are arranged with an eccentricity e with respect to the centres (la,2a,3a) of the wheels. The eccentrical rotational axis (2b,3b) of the second and third wheels (2,3) are fixed at a constant distance 4r (see figure lc).

The angular velocity of the second and third wheels (2,3) is the same but opposite to the angular velocity of the first wheel (1).

Figures la-lc show three consecutive orientations of the wheels (1,2,3) respectively for angles phi=0, 45 and 90 degrees when the wheels rotate from phi=0 to 360 degrees.

In figure la the position of the eccentrical rotational axis (lb) is at its most right position. When the wheels rotate to the position in figure lb, the eccentrical rotational axis (lb) has moved to the left, whereas in figure lc the position of the eccentrical rotational axis (lb) has moved exactly to the middle between the eccentrical rotational axis (2b,3b) (point x). When the wheels rotate further the eccentrical rotational axis (lb) will be moved towards the most left position at phi is 180 degrees, and will be moved to the point x again when phi is 270 degrees. At phi is 360 degrees the eccentrical rotational axis (lb) is back at its most right position as for phi is 0 degrees.

Thus when the wheels rotate, the rotational axis (lb) reciprocates horizontally between the axis

(2b,3b) with an amplitude 2e about the point x. The stroke of the rotational axis (lb) equals 4e. The first wheel rotates thereby around its centre (la), whereas the centre (la) rotates with a radius e around the point x. For every angle phi the centre (la) lies on the horizontal line through the centres (2a,3a) of the second and third wheels (2,3). Thus during rotation the centres (la,2a,3a) of the wheels (1,2,3) do always stay arranged on a straight line.

The distance s between the rotational axis (lb,2b) of the first and second wheels and the distance between the rotational axis (lb,3b) of the first and and third wheels satisfies the formula s=2r-2e*cos(phi), in which phi is the rotational angle of the wheels.

Similar movements apply to other rotational axis (lb') and (lb") of the first wheel which, just like the rotational axis (lb), are located on a circle with radius e and with a centre (la), as indicated in figure lc. The rotational axis (lb') is shifted 180 degrees with respect to the axis (lb). When the wheels rotate, the rotational axis (lb') reciprocates vertically, under an angle of 90 degrees with the line between the rotational axis (2b) and (3b). A rotational axis (lb") located between the rotational axis (lb) and (lb') reciprocates along a rectilinear line (dashed line in figure lc) which makes an angle alpha with the line through the rotational axis (2b) and (3b) and which crosses the line through the rotational axis (2b) and (3b) in the middle at point x.

The wheels (1,2,3) are preferably of the same dimensions. The wheels are preferably standard gear wheels with the same radius r. The wheels have preferably helical teeth. The helical teeth are preferably symmetrical with respect to a plane perpendicular to the rotational axis that divides the thickness of the wheel in two identical halves, e.g. as with fish bone toothing. In this manner, there are no side forces working on the wheels.

The wheels (2,3) are - apart from being connected via a the first wheel (1)- connected via further means, such that these wheels have always the same orientation and angular speed (see figure 2a). In this embodiment the further means are realized with centrical wheels (1',2',3') (i.e. wheels mounted rotatable at their centres) of the same dimensions. All the wheels, except the first wheel (1) have in this case a fixed bearing on the chassis.

In embodiments in which the wheels (2,3) or (2',3') are attached at the ends of the shafts at the rotational axis (2b) or (3b), the further means can be realized with a simple rod S (see figure 2b).

It also possible to realize the further means by means of eccentrical gear wheels, i.e. gear wheels mounted rotatable about an eccentrical axis, such as for example with a second mechanism according to the invention, as shown in figure 4.

In figure 4 four mechanisms I-IV are shown, each having a connecting rod (4). To each connecting rod (4) two pistons are connected (in the figure only the connecting rod (4) of the upper mechanism I is shown). Even when only two mechanisms 1,11 are coupled next to each other, the second and third wheels of the first mechanism I are, apart from being coupled via the first wheel of the first connecting rod, coupled via the first, second and third wheels of the second mechanism II, such that the second and third wheels of both mechanisms can never disengage.

The connecting rods are shown with grooves through which the wheels can pass. Also grooves perpendicular to the plane of he drawing are arranged here, so that the shafts at the rotational axis (2b) and (3b) can pass through the rods. In some arrangements the connecting rods could be guided in these grooves. With the connecting rods extending on both sides of the first wheels, forces between the eccentrical rotational shafts (lb) of the first wheels and the connecting rods can be transferred symmetrically with respect to the central axis of the connecting rods, so that no couple is induced on the rods.

In figures 3a-3d examples are shown of different embodiments of devices according to the invention, which are in particular suitable for straight engines (figures 3a,3e), V- engines (figures 3b,3e), boxer engines (figures 3c,3d,3f,3g) or star engines (figures 3h,3i).

In these embodiments the first wheel (1) is rotatably connected to connecting rod (4) at an eccentrical rotational axis (lb) e.g. by means of a bearing or shaft. In the examples the connecting rod (4) is non hingedly connected to a piston (5) or two pistons (5,6). The pistons are respectively guided in a cylinder (7) or cylinders (7,8). The first wheel (1) is always arranged between a second and third eccentrical wheel (2,3) which have eccentrical rotational axis (2b,3b), at which axis (2b,3b) the wheels have a fixed bearing on a chassis. When transmission chains or belts are used to drive a camshaft of the engine, these chains or belts can also be used as the further means for coupling the second and third wheels (2,3) in their rotation.

In figures 3a-3c the rotational axis of the wheels cross the line of symmetry of the cylinders. In figure 3d the rotational axis of the wheels cross a line parallel to the lines of symmetry of the cylinders. In this embodiment, possible unbalance between the axis is cancelled out and side forces in particular perpendicular to the movement of the pistons are completely obviated. Also the connecting rod can be kept short such that the cylinders can be arranged between the wheels. The rotational axis (2b,3b) can then be arranged in the vicinity of the cylinderheads, so that possibly present overhead camshafts can be driven directly with further gear wheel transmissions. Transmission chains or belts are then not needed anymore.

In figures 3a-3c, the connecting rods (4) can also be arranged parallel to and completely next to the line that crosses the axis (2b) and (3b) perpendicularly. A groove or slot in the connecting rods for the axis (2b) and (3b) is then not necessary, so that the assembly of the device is simplified.

In the embodiment according to figure 3e the connecting rod is attached to the rotational axis (lb'), such that the piston reciprocates vertically. With this construction the length of the connecting rod can be minimized. Furthermore, the connecting rod can be extended like in figure 3 c, so that two pistons can act on the connecting rod.

The choice of rotational axis (lb,lb',lb") where the connecting rod is rotatably connected to the first wheel determines the angle alpha of the reciprocating movement with respect to the line through the rotational axis (2b,3b). The connecting rod can be connected to the first wheel at any

rotational axis (lb") between the axis (lb) and (lb') and lying on the circle with radius r and centre (la). The angle alpha can therefore be chosen according to the circumstances, which allows for a flexible design. A counter balancing mass can be mounted on the first wheel at a location X, whereby this location X and the location of the means (at axis (lb')) for a rotatable connection with the rectilinear reciprocating member (connecting rod) are point symmetrical with respect to the centre of that wheel.

Figure 3f shows an embodiment having further means in the form of a gear wheel (1') mounted in substantially the same plane as the first, second and third wheels (1,2,3). Here the centres of the first, second and third wheel are arranged to form a triangle. Two wheels ( 1,1') are rotatably connected to one connecting rod at the axis (lb) and lb'). The connecting rod is guided in a very stable manner, so that the pistons can act with a minimum force on the cylinder walls (not shown).

Figure 3g shows a similar embodiment with four pistons using only four wheels.

Figure 3h shows an embodiment comprising further means in the form of a gear ring (14), the mechanism having only one fixed rotational axis (lb). One connecting rod is connected to two wheels (2,3). The vertical connecting rod could be extended so as to be guided by a shaft at the axis (lb).

Figure 3i also shows an embodiment comprising a gear ring used as further means, the mechanism having only one fixed rotational axis (lb). The connecting rods of the vertically reciprocating pistons can e.g. be connected at the front of the wheel (1) and connecting rods of the horizontally reciprocating pistons can e.g. be connected behind the wheel (1). This embodiment is particularly easy to balance with only one mass on the first wheel counter balancing the forces of the connecting rods and pistons. Also the mechanisms of all other embodiments can be easily balanced even when used alone. In case there is no set of connecting rods whereby the rods move in perpendicular directions the balancing can be easily achieved by the method comprising amongst others the step of mounting a counter balancing mass at a location on the at least one wheel which is provided with the means for rotatable connection with a rectilinear reciprocating member, whereby said location and the means for rotatable connection with a rectilinear reciprocating member are point symmetrical with respect to the centre of the at least one wheel (1,2,3). Furthermore, mass can be added with respect to at least one fixedly rotateble shaft, preferably on an excentrically mounted wheel on that shaft at the side opposite of the centre, or by taking away mass at the side of the centre of the wheel.

The devices as described with reference to figures 3a-3i can be arranged alone or in any combination next to each other. By arranging embodiments next to each other balancing can often already be achieved without adding balancing masses.

In figure 4 an example of this is shown, with several devices according to figure 3c placed next to each other. Forces and moments due to the reciprocating movements are balanced and thus vibrations are kept to a minimum.

In the figure it is clearly shown, that the axis (lb,2b,3b) coincide with simple straight shafts. On the shafts the gear wheels are mounted with shifted angles with respect to each other. The second and third gear wheels of the first and fourth mechanism (I,IV) are shifted 180 degrees with respect to the second and third wheels of the second and third mechanism (Π,ΙΙΙ). When the pistons of the mechanisms I and IV move to the right, the pistons of the mechanisms II and III move to the left and vice versa.

Because of the purely rectilinear reciprocating movement of the connecting rod, it is relatively easy to vary even during the motion the length of the connecting rod or to adjust the piston relatively to the connecting rod so that the compression ratio can be varied. Furthermore, it is relatively easy to arrange a cooling and/or lubrication for the bearing of the first wheel on the connecting rod and/or the pistons.

An example hereof is shown in figure 5. An axial piston pump (10) pumps oil into the hollow connecting rod (4), so that oil can flow from the pump (10) to the rotational axis (lb) and the piston for cooling and lubrication, whereby in this case the piston of the pump is formed by the connecting rod (4) itself. The connecting rod is composed of two parts which are connected by a screw thread (4'). By turning the left connecting rod part (4") by means of a rack mechanism (9), this part will be axially adjusted with respect to the right connecting rod part. Thus the length between the rotational axis (lb) of the first wheel and the piston (5) is varied, so that the compressed volume and as a consequence the compression ratio will be varied. The length can of course also be varied hydraulically or electromagnetically.

Furthermore, the compression ratio can be varied by varying the position of the bearings of the axis (2b) and (3b) on the fixed chassis (or of the axis (lb) on the fixed chassis, in case this axis has a fixed bearing therein) with respect to the position of the cylinders (7,8). This is indicated with arrow P in figure 5.