A pump apparatus includes a housing, a shaft, a rotor, a plurality of vanes, a pressure relief passage, and a bearing. The housing includes suction ports and discharge ports. The rotor and the vanes transport hydraulic oil to the discharge ports. The hydraulic oil is sucked from the suction ports. The pressure relief passage is defined in a portion of the housing facing an outer peripheral surface of the shaft. The pressure relief passage brings the discharge ports into communication with a low pressure region where the hydraulic oil is low in pressure. When a pressure of the hydraulic oil in the discharge ports is lower than a first predetermined pressure, the bearing keeps the pressure relief passage out of communication with a passage. When the pressure of the hydraulic oil in the discharge ports has increased to reach or exceed the first predetermined pressure, the bearing brings the pressure relief passage into communication with the passage.

A fluid transfer pump that has a housing, a body portion movable within the housing between a first position and a second position, a gear coupled to the housing, a body cavity defined partially between the body portion and the housing, and an aperture defined in the housing that selectively provides a fluid to the body cavity. When the fluid is applied to the body cavity at or above a pilot pressure, the body portion is in the first position adjacent to the gear and when the fluid is applied to the body cavity at a fluid pressure lower than the pilot pressure, the body portion is in the second position and spaced from the gear.

A fluid transfer pump that has a housing, a body portion movable within the housing between a first position and a second position, a gear coupled to the housing, a body cavity defined partially between the body portion and the housing, and an aperture defined in the housing that selectively provides a fluid to the body cavity. When the fluid is applied to the body cavity at or above a pilot pressure, the body portion is in the first position adjacent to the gear and when the fluid is applied to the body cavity at a fluid pressure lower than the pilot pressure, the body portion is in the second position and spaced from the gear.

A fluid transfer pump that has a housing, a body portion movable within the housing between a first position and a second position, a gear coupled to the housing, a body cavity defined partially between the body portion and the housing, and an aperture defined in the housing that selectively provides a fluid to the body cavity. When the fluid is applied to the body cavity at or above a pilot pressure, the body portion is in the first position adjacent to the gear and when the fluid is applied to the body cavity at a fluid pressure lower than the pilot pressure, the body portion is in the second position and spaced from the gear.

A fluid transfer pump that has a housing, a body portion movable within the housing between a first position and a second position, a gear coupled to the housing, a body cavity defined partially between the body portion and the housing, and an aperture defined in the housing that selectively provides a fluid to the body cavity. When the fluid is applied to the body cavity at or above a pilot pressure, the body portion is in the first position adjacent to the gear and when the fluid is applied to the body cavity at a fluid pressure lower than the pilot pressure, the body portion is in the second position and spaced from the gear.

To provide an internal gear pump capable of suppressing a liquid discharge amount during a high-speed rotation by controlling discharge pressure while achieving reduction in size, weight, cost, and the like. An internal gear pump 1 includes: a trochoid 4 in which an inner rotor 3 having a plurality of external teeth is accommodated inside an outer rotor 2 having a plurality of internal teeth in an eccentrically rotatable manner with the external teeth and the internal teeth interdigitated with each other, and a suction-side volume chamber for sucking liquid and a discharge-side volume chamber for discharging the liquid sucked into the suction-side volume chamber are formed between the internal teeth and the external teeth; a casing formed with a recessed part 8 for accommodating the trochoid 4; and a cover 6 that closes the recessed part 8. An ejector 9 is provided to communicate with a flow passage of the liquid formed on a bottom surface of the recessed part 8 and to partially discharge the liquid in an accommodation space of the trochoid formed by the casing and the cover 6.

A compact, modular dosing pump system that is capable of microdose and macrodose volume flow rates, reduces or eliminates the need for additional flow control components such as temperature and pressure sensors, and utilizes a wider operational flow range than existing systems while maintaining the level of accuracy and precision exhibited by conventional dosing pump systems is provided. The dosing pump utilizes a a control system to deliver a range of fluid volumes. The control system monitors the motor emf voltage, calculates the flow rate, and makes adjustments to the pump motor voltage to precisely maintain the desired flowrate.

A compact, modular dosing pump system that is capable of microdose and macrodose volume flow rates, reduces or eliminates the need for additional flow control components such as temperature and pressure sensors, and utilizes a wider operational flow range than existing systems while maintaining the level of accuracy and precision exhibited by conventional dosing pump systems is provided. The dosing pump utilizes a a control system to deliver a range of fluid volumes. The control system monitors the motor emf voltage, calculates the flow rate, and makes adjustments to the pump motor voltage to precisely maintain the desired flowrate.

A variable mechanical lubricant pump provides a pressurized lubricant for an internal combustion engine. The lubricant pump includes a delivery port which is fluidically connected to the engine, a control ring which shifts between a maximum and a minimum eccentricity position, a pump rotor having slidable vanes which rotate in the control ring, a control ring preload spring which pushes the control ring into the maximum eccentricity position, a hydraulic control chamber which pushes the control ring into the minimum eccentricity position, a pressure galley pump port fluidically connected to the engine, and an overpressure valve fluidically associated with the delivery port. The pressure gallery pump port charges the hydraulic control chamber with a gallery pressure to control a remote gallery pressure of the engine via a control chamber pressure in the hydraulic control chamber. The overpressure valve opens if an applied lubricant pressure exceeds a predefined maximum pressure limit.

In a hydraulic control device, when it is detected that a pressure of first oil (output pressure) detected by an output pressure sensor pulsates, a transmission control unit as a TCU stops driving of a second pump or decreases a rotation number of the second pump as a first operation. Alternatively, when it is detected that the output pressure pulsates, the TCU increases the rotation number of the second pump to a rotation number (for example, maximum rotation number) that is higher than a target rotation number as a second operation.