A compressor control module (CCM) controls an output of a variable displacement swash plate compressor. The CCM directly calculates, or receives from an external source, a signal indicating a desired or required output from the compressor, receives a current value of the desired or required output, and receives or calculates a current rotation speed and angle, with respect to a rotation axis, of a swash plate, or a current piston stroke length and a reciprocating frequency of the compressor. The CCM determines a difference between the desired or required output from the compressor and the current value and outputs a signal to a valve driving unit which will adjust an angle of a swash plate such that the actual value becomes closer to, or the same as, the desired or required output, taking into account the additional values received or calculated in the receives or calculates step.

A housing of a hydraulic pump is configured to have a servo unit detachably attached thereto so as to control tilt direction and angle of its movable swash plate. A port block is formed therein with a pair of main ports and, and a pair of main fluid passages and fluidly connecting respective main ports and to cylinders in its cylinder block. Main ports are used to have respective external pipes connected thereto so as to fluidly connect the hydraulic pump to a hydraulic motor disposed outside of the hydraulic pump, thereby constituting a hydrostatic transmission.

A housing of a hydraulic pump is configured to have a servo unit detachably attached thereto so as to control tilt direction and angle of its movable swash plate. A port block is formed therein with a pair of main ports and, and a pair of main fluid passages and fluidly connecting respective main ports and to cylinders in its cylinder block. Main ports are used to have respective external pipes connected thereto so as to fluidly connect the hydraulic pump to a hydraulic motor disposed outside of the hydraulic pump, thereby constituting a hydrostatic transmission.

In an exemplary embodiment, a capacity control valve is provided with a throttle valve portion 12 having a communication hole 23 and a second valve hole 12A. The communication hole 23 is provided between a second valve portion 21B and a third valve portion 21A and makes an intermediate communication passage 26 communicate with a third valve chamber 4. The second valve hole 12A is provided between a second valve chamber 6 and the third valve chamber 4. An amount of narrowing of the throttle valve portion 12 in relation to a stroke of a valve element 21 is large when the second valve portion 21B initially opens by separating from a second valve seat face 6A, and then becomes less after the initial opening of the valve. The capacity control valve is capable of shortening a start-up time and improving the operating efficiency of a variable capacity compressor.

One object is to provide a hydraulic pump that allows a drive source to be started with a small torque. The hydraulic pump includes: a cylinder block having a plurality of cylinder bores and disposed so as to be rotatable; pistons each retained in associated one of the cylinder bores so as to be movable; a swash plate for controlling the amount of movement of the pistons in accordance with the size of the tilt angle; a first pressing unit for pressing the swash plate in such a direction as to reduce the tilt angle of the swash plate; and a second pressing unit for pressing the swash plate in such a direction as to increase the tilt angle of the swash plate by the pressure supplied from the outside.

A piston compressor includes a housing, a drive shaft, a fixed swash plate, a plurality of pistons, a movable body, and a control valve. The housing includes a cylinder block having a plurality of cylinder bores and a plurality of first communication passages. The movable body has a second communication passage that intermittently communicates with each of the first communication passages by rotation of the drive shaft. A flow rate of refrigerant discharged from a compression chamber into a discharge chamber changes according to a position of the movable body in a direction of an axis of the drive shaft. The control valve is configured to control a control pressure. The first communication passages are connected to the second communication passage by the movable body and disconnected from the second communication passage by the drive shaft.

A piston compressor includes a housing, a drive shaft, a fixed swash plate, a plurality of pistons, a movable body, and a control valve. The housing includes a cylinder block having a plurality of cylinder bores and a plurality of first communication passages. The movable body has a second communication passage that intermittently communicates with each of the first communication passages by rotation of the drive shaft. A flow rate of refrigerant discharged from a compression chamber into a discharge chamber changes according to a position of the movable body in a direction of an axis of the drive shaft. The control valve is configured to control a control pressure. The first communication passages are connected to the second communication passage by the movable body and disconnected from the second communication passage by the drive shaft.

A hydraulic axial piston machine includes a drive shaft, a swashplate pivotable about a pivot axis to change inclination relative to a drive shaft axis, and an actuating piston approximately parallel to the drive shaft axis. The actuating piston has a first end which engages and adjusts the swashplate and a second end which bounds an actuating chamber. Fluid flows to the actuating chamber to pivot the swashplate one direction and is forced out of the actuating chamber when the swashplate pivots the other direction. A return element on the actuating piston incorporates a position of the actuating piston and thus the inclination of the swashplate into a control valve. The return element is positioned such that its longitudinal axis and an actuating piston longitudinal axis span a plane that differs from a plane perpendicular to the pivot axis.

A hydraulic axial piston machine includes a drive shaft, a swashplate pivotable about a pivot axis to change inclination relative to a drive shaft axis, and an actuating piston approximately parallel to the drive shaft axis. The actuating piston has a first end which engages and adjusts the swashplate and a second end which bounds an actuating chamber. Fluid flows to the actuating chamber to pivot the swashplate one direction and is forced out of the actuating chamber when the swashplate pivots the other direction. A return element on the actuating piston incorporates a position of the actuating piston and thus the inclination of the swashplate into a control valve. The return element is positioned such that its longitudinal axis and an actuating piston longitudinal axis span a plane that differs from a plane perpendicular to the pivot axis.

Mounting structure for housing-free hydraulic axial piston machines of the bent axis or swash plate design, having a closing plate on which a cylinder block unit with displacing pistons arranged therein is supported, and having a drive or driven shaft. The mounting structure here is designed in the manner of a basket and has a receptacle for the drive or driven shaft and at least two struts which are in each case connected at one end to the receptacle and at the other end to the closing plate in such a manner that the closing plate, the cylinder block unit and the drive or driven shaft are heldanalogously as in a housingin a functionally ready position.