A pump system including a prevention mechanism for preventing excessive fluid temperature buildup of system fluid. The overheat prevention mechanism includes a thermally-responsive control component (130) made with a thermally-responsive material. The thermally-responsive control component is located in the pump system (112) such that the thermally-responsive material is in thermal communication with the system fluid for effecting a change in temperature of the thermally-responsive material. The thermally-responsive material is configured to have an activation temperature that is a predefined amount less than a maximum operating temperature of the system fluid. The thermally-responsive control component is configured to cooperate with a pump control mechanism in the system to decrease pump output pressure in response to the thermally-responsive material being heated by the fluid to a temperature that is equal to or greater than the activation temperature of the thermally-responsive material.

A pump system including a prevention mechanism for preventing excessive fluid temperature buildup of system fluid. The overheat prevention mechanism includes a thermally-responsive control component (130) made with a thermally-responsive material. The thermally-responsive control component is located in the pump system (112) such that the thermally-responsive material is in thermal communication with the system fluid for effecting a change in temperature of the thermally-responsive material. The thermally-responsive material is configured to have an activation temperature that is a predefined amount less than a maximum operating temperature of the system fluid. The thermally-responsive control component is configured to cooperate with a pump control mechanism in the system to decrease pump output pressure in response to the thermally-responsive material being heated by the fluid to a temperature that is equal to or greater than the activation temperature of the thermally-responsive material.

Non-limiting exemplary embodiments of a pumping system and methods for operating the pumping system in a region of high pressure or a region of high flow are disclosed. The pumping system includes a piston disposed within a piston cylinder, a drive shaft, an eccentric coupled to the drive shaft, a connecting arm having opposing first and second ends, and a controller for controlling the rotation of the drive shaft such that the piston oscillates within a region of high pressure or a region of high flow.

A pump control system includes a pump operable via actuation of an actuator that moves an actuating element to cause the pump to generate an intake stroke and a discharge stroke to pump media along a pipe or conduit. A sensor is disposed at the actuator and is operable to sense the position of the actuating element during operation of the actuator and pump. A controller is operable to control the actuator. The controller, responsive to an output of the sensor, determines the current position of the actuating element and automatically controls the actuator to provide a selected performance of the pump.

A pump control system includes a pump operable via actuation of an actuator that moves an actuating element to cause the pump to generate an intake stroke and a discharge stroke to pump media along a pipe or conduit. A sensor is disposed at the actuator and is operable to sense the position of the actuating element during operation of the actuator and pump. A controller is operable to control the actuator. The controller, responsive to an output of the sensor, determines the current position of the actuating element and automatically controls the actuator to provide a selected performance of the pump.

A hydraulic transaxle comprises an axial piston hydraulic pump having a variable displacement, and a transaxle casing incorporating the hydraulic pump. The hydraulic pump includes a movable swash plate and a pair of trunnion shafts. The transaxle casing includes a pair of side walls, and includes a pair of casing holes each of which penetrates each of the side walls between an inside and an outside of the transaxle casing. The pair of trunnion shafts are passed through the respective casing holes. The swash plate is formed with a pair of swash plate holes in the respective side portions facing the respective side walls in the inside of the transaxle casing. Proximal end portions of the respective trunnion shafts are inserted into the respective swash plate holes. A distal end portion of one of the trunnion shafts projects from the corresponding casing hole to the outside of the transaxle casing.

A swash plate type variable displacement compressor includes, a housing, a swash plate disposed in the housing and having therethrough an insertion hole, a rotary shaft inserted through the insertion hole of the swash plate, a plurality of pistons engaged with the swash plate, and a connecting member disposed between the rotary shaft and the swash plate and connecting the rotary shaft and the swash plate so as to change inclination angle of the swash plate relative to the rotary shaft. A pair of projections are provided in the insertion hole so as to extend toward the rotary shaft and restrict the movement of the swash plate relative to the rotary shaft. The paired projections are spaced away from each other so as not to be in contact with the rotary shaft simultaneously.

An engine (12) drives a variable capacity-type hydraulic pump (16), discharged hydraulic oil is selectively supplied to a cooling fan (19) and a hoist cylinder (11) in accordance with switching of a selection valve (17), thereby controlling the same on the basis of each target value. A pump discharge pressure (Pp) of the hydraulic oil discharged from the hydraulic pump (16) and a motor supply pressure (Pm) of the hydraulic oil supplied to a hydraulic motor (18) via the selection valve (17) are detected by sensors (27, 28) and are compared with pressure determination values stored in advance as a pump discharge pressure (Pp) and an actuator supply pressure (Pm) generated when the target value is achieved. Presence/absence of abnormality in the hydraulic actuator control device (15) is determined on the basis of a result of the comparison, and when abnormality is determined to have occurred, control is performed to minimize the capacity of the hydraulic pump (16).

A breast pump according to the present invention includes a variable pressure generating unit, the variable pressure generating unit including a power driving unit including a stepping motor that is capable of rotating both normally and in reverse, and a negative pressure forming unit that creates a negative pressure state periodically by causing an elastic body to deform in accordance with a cycle period formed by the power driving unit, wherein the negative pressure forming unit is coupled to the expressing unit, and the stepping motor is capable of modifying an amplitude of the cycle period and the cycle period during negative pressure formation as desired. Hence, a suction pressure and a pressure increase/decrease cycle can both be set as desired, and moreover, a breast pump that uses electric power can be constructed compactly.

A breast pump according to the present invention includes a variable pressure generating unit, the variable pressure generating unit including a power driving unit including a stepping motor that is capable of rotating both normally and in reverse, and a negative pressure forming unit that creates a negative pressure state periodically by causing an elastic body to deform in accordance with a cycle period formed by the power driving unit, wherein the negative pressure forming unit is coupled to the expressing unit, and the stepping motor is capable of modifying an amplitude of the cycle period and the cycle period during negative pressure formation as desired. Hence, a suction pressure and a pressure increase/decrease cycle can both be set as desired, and moreover, a breast pump that uses electric power can be constructed compactly.