A rotary fluid pump-motor includes first and second rotor assemblies and a bent cylinder sleeve. The first rotor assembly includes a first rotor, a piston cylinder, and a flange ring with an inclined guide surface. The second rotor assembly includes a second rotor and a piston. The first and second rotors are rotatably movable about inclined first and second rotor axes, respectively. The bent cylinder sleeve receives the piston cylinder and the piston therein through respective sleeve openings to define a piston chamber therebetween. The bent cylinder sleeve is in at least intermittent contacting relationship with the flange ring's inclined guide surface and rotatably movable about the first rotor axis with respect to the inclined guide surface such that the bent cylinder sleeve moves along the first rotor axis relative to the piston cylinder based upon its circumferential position along the inclined guide surface to correspondingly vary the piston chamber's volume.

A rotary fluid pump-motor includes first and second rotor assemblies and a bent cylinder sleeve. The first rotor assembly includes a first rotor, a piston cylinder, and a flange ring with an inclined guide surface. The second rotor assembly includes a second rotor and a piston. The first and second rotors are rotatably movable about inclined first and second rotor axes, respectively. The bent cylinder sleeve receives the piston cylinder and the piston therein through respective sleeve openings to define a piston chamber therebetween. The bent cylinder sleeve is in at least intermittent contacting relationship with the flange ring's inclined guide surface and rotatably movable about the first rotor axis with respect to the inclined guide surface such that the bent cylinder sleeve moves along the first rotor axis relative to the piston cylinder based upon its circumferential position along the inclined guide surface to correspondingly vary the piston chamber's volume.

In accordance with at least one aspect of this disclosure, a system includes, a cylinder barrel configured to rotate within a pump housing of a pump operatively connected to a driving member of the pump via a first shaft. A piston is seated within a bore defined in the cylinder barrel. The piston is operatively connected to the driving member of the pump via a second shaft. The first shaft and the second shaft each include a ball end configured to seat within the driving member. In embodiments, the ball end of at least the second shaft is of silicon nitride.

In accordance with at least one aspect of this disclosure, a system includes, a cylinder barrel configured to rotate within a pump housing of a pump operatively connected to a driving member of the pump via a first shaft. A piston is seated within a bore defined in the cylinder barrel. The piston is operatively connected to the driving member of the pump via a second shaft. The first shaft and the second shaft each include a ball end configured to seat within the driving member. In embodiments, the ball end of at least the second shaft is of silicon nitride.

Methods and systems for a variable displacement bent axis piston motor are described. In one example, a variable displacement bent axis piston motor comprises a bent axis unit (BAU) rotary group including a cylinder block coupled to a drive shaft of the bent axis piston motor, and an electric actuator coupled to a servo piston of the bent axis piston motor, wherein a displacement of the BAU rotary group is controlled by an inclination angle between the drive shaft and a valve plate of the BAU rotary group coupled to the cylinder block, the inclination angle controlled by the servo piston, the servo piston controlled by the electric actuator. The servo piston is controlled by the electric actuator based a feedback control system, which may switch between various control strategies for adjusting the inclination angle based on different driving scenarios.

Methods and systems for a variable displacement bent axis piston motor are described. In one example, a variable displacement bent axis piston motor comprises a bent axis unit (BAU) rotary group including a cylinder block coupled to a drive shaft of the bent axis piston motor, and an electric actuator coupled to a servo piston of the bent axis piston motor, wherein a displacement of the BAU rotary group is controlled by an inclination angle between the drive shaft and a valve plate of the BAU rotary group coupled to the cylinder block, the inclination angle controlled by the servo piston, the servo piston controlled by the electric actuator. The servo piston is controlled by the electric actuator based a feedback control system, which may switch between various control strategies for adjusting the inclination angle based on different driving scenarios.

A bent-axis machine comprises a housing having a control cover and a piston drum which is rotatably mounted in the housing on a valve plate and which has axial cylinders, each of which receives a piston. An adjustment system includes a pivot cradle via which the piston drum and the valve plate can be pivoted relative to the drive axis about a maximum working range which is delimited by a minimum pivot angle and a maximum pivot angle. The minimum pivot angle of the working range is shifted out of its zero position by at least 5, and the maximum pivot angle is extended in the same way by at least 5 in order to retain the entire working range about the region left out of the lower region.

A bent-axis machine comprises a housing having a control cover and a piston drum which is rotatably mounted in the housing on a valve plate and which has axial cylinders, each of which receives a piston. An adjustment system includes a pivot cradle via which the piston drum and the valve plate can be pivoted relative to the drive axis about a maximum working range which is delimited by a minimum pivot angle and a maximum pivot angle. The minimum pivot angle of the working range is shifted out of its zero position by at least 5, and the maximum pivot angle is extended in the same way by at least 5 in order to retain the entire working range about the region left out of the lower region.

In accordance with at least one aspect of this disclosure, a system includes, a cylinder barrel configured to rotate within a pump housing of a pump operatively connected to a driving member of the pump via a first shaft. A piston is seated within a bore defined in the cylinder barrel. The piston is operatively connected to the driving member of the pump via a second shaft. The first shaft and the second shaft each include a ball end configured to seat within the driving member. In embodiments, the ball end of at least the second shaft is of silicon nitride.

In accordance with at least one aspect of this disclosure, a system includes, a cylinder barrel configured to rotate within a pump housing of a pump operatively connected to a driving member of the pump via a first shaft. A piston is seated within a bore defined in the cylinder barrel. The piston is operatively connected to the driving member of the pump via a second shaft. The first shaft and the second shaft each include a ball end configured to seat within the driving member. In embodiments, the ball end of at least the second shaft is of silicon nitride.