ROTATABLE PISTON ASSEMBLY

1 . A rotatable piston assembly for a reciprocating piston type hydraulic machine, the rotatable piston assembly comprising:

a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine along a cylinder bore axis of the cylinder bore, wherein

the reciprocating piston type hydraulic machine is an axial piston machine comprising a rotating swash mechanism configured for variable displacement, a stationary cylinder block, and a rotatable shaft coupled to the rotating swash mechanism, and

the rotating swash mechanism is a rotating wobble plate connected to a swash collar through a plurality of bearings, and the swash collar is connected to the rotatable shaft through a plurality of bearings.

2 . The rotatable piston assembly of claim 1 , wherein the axial piston machine comprises:

a manifold disposed within the stationary cylinder block and a swash housing configured to house a double sided piston configuration, the manifold configured for fluid communication with the rotatable piston assembly, the manifold comprising:

a proximal manifold port disposed at a proximal end of the manifold within the stationary cylinder block;

a proximal manifold passage in fluid communication with the proximal manifold port and comprising a plurality of proximal manifold passage port openings;

a distal manifold port disposed along a distal end of the manifold within the stationary cylinder block;

a distal manifold passage in fluid communication with the distal manifold port and comprising a plurality of distal manifold passage port openings;

a proximal inward cylinder block port disposed in the stationary cylinder block and in fluid communication with one of the plurality of proximal manifold passage port openings;

a proximal outward cylinder block port in fluid communication with an outward proximal manifold passage port opening;

a distal inward cylinder block port disposed in the stationary cylinder block and in fluid communication with one of the plurality of distal manifold passage port openings; and

a distal outward cylinder block port in fluid communication with an outward distal manifold passage port opening.

3 . The rotatable piston assembly of claim 2 , wherein the rotating wobble plate comprises a pair of opposed plate bearing surfaces, the rotatable piston comprises a double sided configuration and an intermediate piston constrained joint interface disposed between ends of the rotatable piston, the rotatable piston assembly comprising:

a slipper assembly configured to couple with and constrain rotation of the rotatable piston about the intermediate piston constrained joint interface, the slipper assembly comprising:

a slipper shoe comprising a proximal interface and a distal interface configured to be disposed between the pair of opposed plate bearing surfaces of the rotating wobble plate, the rotatable piston configured for a controlled rotation with respect to the rotating wobble plate and

a slipper pin configured to couple the slipper shoe to the rotatable piston at the intermediate piston constrained joint interface.

4 . The rotatable piston assembly of claim 3 , further comprising a plurality of pistons, a plurality of slipper assemblies, and a plurality of proximal and distal outward cylinder block ports, each slipper assembly coupled to a respective piston, wherein

a first end of each piston aligns with the proximal inward cylinder block port in fluid communication with one of the plurality of proximal manifold passage port openings of the proximal manifold passage or aligns with the proximal outward cylinder block port in fluid communication with the outward proximal manifold passage port opening as the rotatable piston rotates,

a second end of each piston aligns with the distal inward cylinder block port in fluid communication with one of the plurality of distal manifold passage port openings of the distal manifold passage or aligns with the distal outward cylinder block port in fluid communication with the outward distal manifold passage port opening as the rotatable piston rotates, and

when the first end of each piston aligns with one of the proximal inward cylinder block port or the proximal outward cylinder block port, the second end of each piston respectively aligns with one other of the distal outward cylinder block port or the distal inward cylinder block port as the rotatable piston rotates.

5 . The rotatable piston assembly of claim 1 , the axial piston machine comprising a plurality of housing fluid passages configured for control by an externally coupled flow control device, a plurality of shaft fluid passages configured to be in fluid communication with at least one of the plurality of housing fluid passages, and a control piston chamber configured to be in fluid communication with the plurality of shaft fluid passages for receipt of pressured control fluid.

6 . The rotatable piston assembly of claim 5 , the axial piston machine comprising a control piston and a bias spring disposed within the swash collar and configured to adjust a tilt angle of the rotating wobble plate with respect to an axis of the rotatable shaft.

7 . The rotatable piston assembly of claim 6 , wherein

the control piston and the bias spring are supported by the rotatable shaft and coupled to the swash collar,

the bias spring is configured to tilt the swash collar with respect the rotatable shaft, and

the control piston is configured to cooperate with the control piston chamber and reciprocate within a bore defining the control piston chamber such that the control piston and the bias spring are configured to adjust the tilt angle of the rotating wobble plate with respect to the axis of the rotatable shaft based on a received amount of pressurized control fluid.

8 . The rotatable piston assembly of claim 1 , wherein the axial piston machine comprises a plurality of bearing components between an interface of the swash collar and the rotatable shaft.

9 . The rotatable piston assembly of claim 8 , wherein the plurality of bearing components comprise a plurality of hydrostatic pressure pockets included at the interface of the swash collar and the rotatable shaft.

10 . The rotatable piston assembly of claim 9 , wherein each hydrostatic pressure pocket is defined within an interior wall surface of the swash collar facing an exterior wall surface of the rotatable shaft.

11 . The rotatable piston assembly of claim 10 , wherein a seal component is disposed between the exterior wall surface of the rotatable shaft and the interior wall surface of the swash collar defining each respective hydrostatic pressure pocket to provide a seal about the hydrostatic pressure pocket.

12 . The rotatable piston assembly of claim 1 , wherein each rotatable piston comprises a first integral valve port at a first end.

13 . The rotatable piston assembly of claim 12 , wherein each rotatable piston comprises a second integral valve port at a second end opposing the first end.

14 . The rotatable piston assembly of claim 13 , wherein the first integral valve port is circumferentially disposed with respect to the second integral valve port.

15 . The rotatable piston assembly of claim 14 , wherein the first integral valve port is circumferentially disposed at 180 degrees with respect to the second integral valve port.

16 . A method for using an axial piston machine as at least one of a pump and a motor, the axial piston machine including a rotating swash mechanism configured for variable displacement, a stationary cylinder block, and a rotatable shaft coupled to the rotating swash mechanism, the method comprising:

reciprocating a rotatable piston of a rotatable piston assembly including a double sided piston configuration in a cylinder bore of the stationary cylinder block of the axial piston machine;

rotating the rotatable piston in the cylinder bore during reciprocation; and

controlling rotation of the rotatable piston in the cylinder bore through a rotational control assembly, wherein rotation of the rotating swash mechanism is configured to rotate the rotational control assembly.

17 . The method of claim 16 , wherein the rotatable piston comprises a first integral valve port at a first end and a second integral valve port at a second end that is circumferentially disposed with respect to the first end, and the first integral valve port and the second integral valve port are configured to provide a passage for fluid flow in one of a pump direction and a motor direction opposite the pump direction to respectively act as one of the pump and the motor.

18 . The method of claim 16 , wherein the rotational control assembly comprises a slipper assembly configured to couple with the rotatable piston at an intermediate piston constrained joint interface with a slipper pin and to constrain rotation of the rotatable piston about the intermediate piston constrained joint interface.

19 . The method of claim 16 , further comprising:

adjusting a tilt angle of the rotating swash mechanism comprising a rotating wobble plate with respect to an axis of the rotatable shaft through positioning of a control piston and a bias spring disposed within a swash collar coupling the rotatable shaft to the rotating wobble plate and based on an amount of pressured control fluid received in a control piston chamber.

20 . The method of claim 19 , wherein the control piston is configured to cooperate with the control piston chamber and reciprocate within a bore defining the control piston chamber, the control piston chamber in fluid communication with a plurality of shaft fluid passages that are in fluid communication with a plurality of housing fluid passages configured for control by an externally coupled flow control device.