Field of The Invention The field of the invention is hydraulic motors.

Background of The Invention Hydraulic motors frequently convert energy obtained from a working fluid into rotational movement of a crankshaft. Such conversion is often accomplished by introducing the working fluid into a cylinder containing a piston to cause the piston to move. The piston is generally coupled to a crankshaft via a piston rod with movement of the piston corresponding to rotation of the crankshaft. The piston generally moves back and forth in a reciprocating fashion within the cylinder with such reciprocating motion being the result of interaction of the piston with the crankshaft (and other pistons via the crankshaft), and/or through control of fluid flow into and out of the cylinder. The working fluid in some instances may be a liquid, while in other instances it may be a gas.

Movement of a piston from one end of the limit of its motion to another within the cylinder is generally referred to as a stroke, and the combination of pairs of strokes during which the piston is displaced from and subsequently returns to a starting position within the cylinder as cycles. In many instances each piston cycle comprises both a power stroke and a recovery stroke with fluid entering the cylinder and forcing movement of the piston during the power stroke, and fluid exiting the cylinder during the recovery stroke. Movement of the piston during the recovery stroke is generally the result of continued rotation of the crankshaft due to inertia or to power strokes provided by one or more other pistons coupled to the crankshaft. The cycle of each piston in such an instance may be referred to as a push-pull cycle as the piston is alternately pushing and being pulled by the crankshaft. The use of a push-pull cycle is not always desirable as a piston is only contributing to rotation of the crankshaft during 50% of its cycle.

In other instances, each stroke of a piston is a power stroke with fluid entering the cylinder on one side of the piston and forcing movement of the piston at the same time as

fluid is being exhausted from the cylinder on the opposite side of the piston. An example of a motor having pistons using such a push-push or double-acting cycle can be found in U. S.

Patent Application No. 4,106,391 issued to R. Wheeler in 1978. Motors such as the one described in the'391 patent are often more desirable than push-pull type motors because each cylinder is contributing to rotation of the crankshaft during most if not all of each cycle.

Unfortunately, motors such as the one described in the'391 patent tend be less efficient than is desirable, and to be costly to build and maintain. Lower efficiency and increased costs associated with known push-push cycle motors may be due at least in part to the added complexity resulting from implementing a push-push cycle for each piston.

Motor improvements that result in motors that operate more efficiently and that can be built and maintained at a lower cost than existing motors have been and continue to be desirable. As the use of hydraulic motors is often advantageous, it is also desirable that improvements that result in more efficient and cheaper hydraulic motors be obtained, Summary of the Invention The present invention is directed to a hydraulic motor wherein the number and placement of cylinder fluid inlet and outlets facilitates input and exhaust fluid distribution and control via a reduced number of valves and flow paths, and also provides for a clearer flow path for fluid passing through the motor. More specifically, the present invention is directed to a motor that comprises a cylinder having a cavity subdivided into variable volume upper and lower cavities by a piston that reciprocates within the cylinder cavity. Each of the upper and lower cylinder cavities includes both inlet and outlets through which fluid flows into and out of the respective cavities. The lower cavity also comprises an opening through which a piston rod passes to couple the cylinder to a crankshaft via a Scotch yoke. The motor also comprises a cylindrical flow control valve coupled to the crankshaft. Fluid flowing into and out of the cylinder passes through the flow control valve allowing the flow control valve to control such fluid flow. The cylindrical flow control valve is coupled to the inlet and outlets of the cylinder by two distribution manifolds with each manifold providing a flow path between the control valve and at least one port of each of the upper and lower cavities.

In a preferred embodiment, the motor comprises at least four cylinders having the previously described characteristics with all of the inlet and outlets of the cylinder being coupled to the same cylindrical control valve via the same pair of distribution manifolds.

Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.

Brief Description of The Drawings Fig. 1 is a perspective view of a motor embodying the invention.

Fig. 2 is an exploded perspective view of the motor of figure 1 without distribution manifolds.

Fig. 3 is partial cutaway perspective view of a cylinder of the motor of figure 1.

Fig. 4 is cutaway perspective view of a cylinder of the motor of figure 1 having a piston positioned within it.

Fig. 5 is a front exploded perspective view of the cylinder blocks of the motor of figure 1.

Fig. 6 is a back exploded perspective view of the cylinder blocks of the motor of figure 1.

Fig. 7 is a bottom view of a cylinder block of the motor of figure 1.

Fig. 8 is a perspective view of the crankshaft, piston, and yoke assembly of figure 1.

Fig. 9 is a perspective view of the crankshaft of the motor of figure 1.

Fig. 10 is an exploded perspective view of a Scotch yoke and bearing of the motor of figure 1 Fig. 11 is a perspective view of the valve housing of the motor of figure 1.

Fig. 12 is a perspective view of the control valve of the motor of figure 1.

Fig. 13 is a perspective view of a distribution manifold of the motor of figure 1.

Fig. 14 is a view of the distribution manifold of Fig. 13 showing the flow paths within the manifold.

Detailed Description Referring to figures 1 and 2, motor 10 comprises cylinder blocks 100T and 100B, cylinder heads 200T and 200B, distribution manifolds 300L and 300R, and control valve housing 400. Cylinder blocks 100T and 100B are coupled together to form a crankcase containing a crankshaft 500 and Scotch yokes 600 coupled to piston assemblies 700. Valve housing 400 contains a directional flow rotary valve 410 coupled to an end of crankshaft 500.

From the figures it can be seen that motor 10 comprises a boxer arrangement of horizontally opposed pistons but does not include a traditional valve train with the associated cam or push rods.

Each cylinder block 100T and 100B comprises two cavities that will be referred to as cylinders at least in part because of their cylindrical shape. (It should be noted that although the term cylinders is used herein for the sake of clarity, various embodiments may utilize cavities/cylinders which are not cylindrical in shape.) Although the actual number of cylinders may vary between embodiments, each cylinder is preferred to comprise the feature illustrated in figure 3. In preferred embodiments, the top and bottom halves T and B of cylinder C will be symmetrical, as will the left and right sides L and R. As used herein the left side of the cylinder L is the portion of the cylinder on a first side of an imaginary plane PI in which the center axis Al of the cylinder lies, and the right side of the cylinder R is the portion of the cylinder on the side of the imaginary plane PI opposite the first side. Similarly, the top half T of cylinder C is the portion of the cylinder on a first side of an imaginary plane P2 which is perpendicular to plane P I and which divides the cavity/cylinder C into two equal halves, and the bottom half B of cylinder C is the portion of the cylinder on the opposite side of plane P2.

In order to achieve the preferred symmetries, the cylinder will include an even number of ports, with the number of ports on the top half of the cylinder being equal to the number of

ports on the bottom half of the cylinder, and the number of ports on the right side of the cylinder being equal to the number of ports on the left side of the cylinder. It is desirable to have symmetry between the top and bottom halves of cylinder C because it permits the cylinder to be divided into two variable volume chambers by (see figure 4) positioning a piston (comprising rod 710 and head 720) within cylinder C such that it can slide up and down within cylinder C. The use of two variable volume chambers having a piston between them allows the motor to be configured such that the piston operates on a push-push cycle. It is desirable to have symmetry between the left and right sides of cylinder C in order to allow the configuration of the motor to be modified without requiring changes to cylinder C.

It is currently preferred that cylinder C comprise four ports, L1, L2, Rl, and R2.

Although two of the four ports will act as inlets into cylinder C, and two will act as outlets from cylinder C, the actual function of a particular port is determined by mechanisms outside the cylinder which control fluid flow into and out of the cylinder via the ports. Of the two inlets, one acts as an inlet into the variable volume chamber above piston P, and the other into the variable volume chamber below piston P. Similarly, the two outlets are split between the upper and lower variable volume chambers to provide an outlet to each chamber. For the discussion purposes port Ll will be viewed as the inlet to the upper chamber and port Rl as the inlet to the bottom chamber. R2 will be viewed as the outlet to the upper chamber, and L2 as the outlet to the bottom chamber. Various embodiments may incorporate different numbers of ports, or may have more or less inlets than outlets.

For the purposes of this disclosure, it is helpful to view a chamber's pair of inlet and outlets as having an orientation defined by a directional vector V that indicates the direction fluid would flow if it were allowed to pass directly through the chamber from the inlet to the outlet. In preferred embodiments, the ports of the top/upper chamber will have an orientation that is the reverse of the orientation of the ports of the bottom/lower chamber. Thus, each side of cylinder C has an inlet to one chamber and the outlet to the other. It is contemplated that configuring the motor such that the orientation differs between the upper and lower chambers allows the use of simpler manifolds and valves.

It is also preferred that the inlet and outlets of cylinder C be positioned such that an additional cylinder may be positioned adjacent to cylinder C without obstructing the inlet and

outlets of cylinder C, or making it difficult to couple a manifold providing flow paths to and from cylinder C to cylinder C. Thus, in a preferred embodiment, the inlet and outlets will be centered on an axis A2 (see figure 3) laying in a plane P3 that is perpendicular to both planes P 1 and P2.

Referring to figures 5,6, and 7, each of cylinder blocks 100T and 100B comprises two cylinders (110 and 120 for block 100T, 130 and 140 for block 100B), two upper cavity inlets (111 and 121 for block 100T, and 131 and 141 for block 100B), two lower cavity inlets (113 and 123 for block 100T, and 133 and 143 for block 100B), two upper cavity outlets (112 and 122 for block 100T, and 132 and 142 for block 100B), two lower cavity outlets (114 and 124 for block 100T, and 134 and 144 for block 100B). The inlet and outlets pass through the blocks to form flow paths extending between the exterior of the block and the cylinders (110, 120,130, and 140).

Cylinder blocks 100T and 100B, when coupled together, form a cylindrical crankcase 150 that is subdivided into two cavities 151 and 152 by crankshaft support members 153A, 153B, 154A, 154B, 155A, and 155B. Each crankshaft support member includes a : contacting portion 156.

Figures 8 through 10 show a preferred combination of crankshaft, pistons, bearings, and Scotch yokes. As can be seen from the figures, pairs of piston assemblies 700 (each piston assembly comprising a piston head 720 and a piston rod 710) are coupled via piston rods 710 to crankshaft 500 via Scotch yokes 600. The use of Scotch yokes rather than coupling the piston rods 710 of piston assemblies 700 to crankshaft 500 permits enclosing the bottom chamber/cavity of each cylinder with a wall having an opening through which a piston rod 710 can slide in a linear fashion rather than an opening allowing for non linear movement of the piston rod 710. In preferred embodiments, Scotch yokes 600 will comprise at least two pieces 600A and 600B that can be bolted together to permit the yokes to be easily coupled to crankshaft 500.

Bearings 520 are preferably used as an interface between Scotch yokes 600 and crankshaft 500. Bearings 520 preferably comprise a cylindrical cavity 521 and a pair of parallel flat surfaces 522 positioned between bearing retaining flanges 523. It is contemplated that cylindrical cavity 521 will help distribute forces exerted between the yoke and crankshaft

across a larger surface of the crankshaft, and that surfaces 522 will provide a larger surface for distributing forces to and from the yokes 600. Bearings 520 are preferably formed from two halves that can be positioned about crankshaft 500 at the time yokes 600 are coupled to the crankshaft 500.

Crankshaft 500 is preferably formed as a single piece and comprises counterweights 510 to add additional mass to and help balance the movement of the assembly. It is contemplated that in alternative embodiments, counterweights may be formed from pieces separate from that of crankshaft 500 and to be adjustably connected to crankshaft 500 to permit adjustment of their positions on the crankshaft to allow balance adjustments to the assembly.

The piston, Scotch yoke, bearing crankshaft assembly shown is adapted to allow a linear reciprocating motion of the piston assembly to be transformed into rotation of the crankshaft with the crankshaft rotating within bearings 520, and bearings 520 sliding back and forth within yokes 600 while yokes 600 move up and down with piston assemblies 700.

It should be noted that one end of crankshaft 500 comprises a number of splines 530 and is adapted to allow a rotary valve to be mounted to it. The inclusion of the splines 530 allows for incremental adjustment of the valve relative to the crankshaft in order to adjust motor timing. In a preferred embodiment, the number of splines will be greater than or equal to 90 in order to allow adjustment in 4 degree increments. It is contemplated that alternative embodiments may utilize a plurality of valves each of which may be mounted to crankshaft 500 but which can be adjusted separately from each other.

Referring to figure 2,11, and 12 a rotary valve assembly comprises a housing 400 and contains a directional flow rotary valve 410 coupled to an end of crankshaft 500 via crankshaft spline receiving portion 411. In a preferred embodiment, housing 400 comprises two cylinder fluid outlets 401L and 401R, and two cylinder fluid inlets 402L and 402R.

Housing 400 also comprises at least one motor fluid outlet 403 and at least one motor fluid inlet 404. Fluid inlet 404 provides a mechanism for coupling motor 10 to a pressurized fluid source, and fluid outlet 403 provides a mechanism for handling fluid after it is exhausted from motor 10. Housing 400 also comprises cavity 406 which is the cavity within which

valve 410 rotates and flange 405 which is used to couple housing 400 to cylinder blocks 100T and 100B.

Valve 410 comprises two adjacent fluid flow chambers 412 and 413, and a dividing wall 414. The rotation of valve 410 within housing 400 alternately opens and closes flow paths between motor fluid outlet 403 and cylinder fluid outlets 401L and 401R, and between motor fluid inlet 404 and cylinder fluid inlets 402L and 402R. In the preferred embodiment, valve 410 provides a flow path between motor fluid inlet 404 and cylinder fluid inlet 402L while simultaneously providing a flow path between motor fluid outlet 403 and cylinder fluid outlet 401L during 1/2 of each rotation of the crankshaft, and provides a flow path between motor fluid inlet 404 and cylinder fluid inlet 402R while simultaneously providing a flow path between motor fluid outlet 403 and cylinder fluid outlet 401R during the other 1/2 of each rotation of the crankshaft. Provision of flow paths at the appropriate times results from alignment of chambers 412 and 413 with the various inlets and outlets during rotation of valve 410.

Referring to figures 13 and 14, distribution manifolds 300L and 300R each comprise flow channels 301 and 302 that define two flow paths through each manifold. In a preferred embodiment, flow channel 301 of manifold 300L provides a common flow path between outlets 111,123,131, and 143 and cylinder fluid outlet 401L, and flow channel 302 of manifold 300L provides a common flow path between inlets 114,122,134, and 142 and cylinder fluid inlet 402L. Similarly, flow channel 301 of manifold 300R provides a common flow path between outlets 113,121,133, and 141 and cylinder fluid outlet 401L, and flow channel 302 of manifold 300R provides a common flow path between inlets 112,124,132, and 144 and cylinder fluid inlet 402R. Distribution manifolds 300L and 300R each comprise a contacting surface 305 adapted to be coupled to cylinder housings 100B and 100T.

The following table illustrates the flow path of the working fluid through the motor: Dir. Cyl. Stroke 1Stroke 2 In 110 404->412->402L->302->114->110 404->412->402R->302->112->110 Out 110 110->111->301->401L->413->403 110->-113>301->401R->413->403 In 120 404->412->402L->302->122->120 404->412->402R->302->124->120 Out 120 120->123->301->401L->413->403 120->121->301->401R->413->403 In 130 404->412->402L->302->134->130 404->412->402R->302->132->130 Out130 130->131->301->401L->413->403 130->133->301->401R->413->403

I In 140 404->412->402L->302->142->140 404->412->402R->302->144->140 Out 140 140->143->301->401L->413->403 140->141->301->401R->413->403 From the table it can be seen that, for the first stroke (Stroke 1) of a cycle, working fluid flows into the motor via motor fluid inlet 404, from inlet 404 through chamber 412, out cylinder fluid inlet 402L, through manifold flow path 302 of manifold 300L, and into cylinder 110 via port 114. During the second stroke (Stroke 2) of the same cycle, fluid exits cylinder 110 via port 113, flows through flow path 113 into cylinder fluid outlet 401R, flows through chamber 413 and out of the motor via motor fluid outlet 403. It can also be seen that during the first stroke, fluid flows out of cylinder 110 and into flow path 301 via port 111, and then into cylinder fluid inlet port 401L, through chamber 413, and out motor outlet port 403. The flow into and out of the other cylinders occurs in a similar fashion as shown in the table.

It is preferred that motor 10 not be lubricated. Instead all wear surfaces of the motor are preferred to be coated with friction reducing material such as nickel cadmium Teflon.

Thus, a preferred embodiment will have a nickel cadmium Teflon coating on each of any two surfaces which come in contact with each other such as the walls of the cylinders and the piston heads, the contact surfaces of the Scotch yokes, bearings, crankshaft, and crankcase, and the valve housing and valve. It is preferred that any two surfaces which come in contact with each other be machined or otherwise formed to have approximately 1/1000th of an inch clearance between them. Thus the cylinders would have a diameter approximately 2/1000th of an inch larger than the diameter of the piston heads. Similarly, the diameter of the valve would be approximately 2/1000th of an inch smaller than the diameter of the valve housing. It should be noted that the working fluid used to drive the motor may act as a lubricant, but lubrication by the working fluid is not required for operation of preferred embodiments of motor 10.

It is contemplated that embodiments of motor 10 may be modified to facilitate ganging such that a plurality of motors 10 may be coupled together via their crankshafts. It is contemplated that motor 10 may be advantageously ganged because motor 10 is self- synchronizing. Synchronization of any such ganged motors can be achieved by simply ensuring that each ganged motor is provided with fluid at the same rate and pressure.

It is contemplated that providing separate inlet and outlet pairs for each half cylinder cavity provides for reconfiguration of motor 10 by simply modifying the manifolds and/or control valve. The current configuration of alternating orientations between upper and lower ports results in motor inputs and outputs being divided in a manner that only the left or the right side ports are active at any given time. An alternative arrangement would be to have all the ports have the same orientation, to use the same manifolds, but to modify the control valve assembly such that the two cylinder fluid inlets were adjacent each other on one side of the housing while the two cylinder fluid outlets were adjacent each other on the opposite side of the housing. Motor 10 is also contemplated as being easily reconfigured to handle different pressure and/or power requirements by providing alternative manifold and valve embodiments.

Thus, specific embodiments and applications of hydraulic motors have been disclosed.

It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms"comprises"and"comprising"should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.