Abstract: A spool valve includes: a sleeve extending in an axial direction thereof, including inlet and outlet ports for working fluid; a spool housed in the sleeve; a biasing device that presses a base end of the spool toward a tip end of the spool; and a pressure detecting port opening toward the tip end. The spool includes: first and second land sections; a groove section located between the first land section and the second land section, having a width in the axial direction to connect between the inlet port and outlet port; a recess portion formed on an outer peripheral surface of the second land section; and a connection passage for the working fluid formed in the second land section, connecting between the groove section and the recess portion. A path hole is formed in the sleeve facing the recess portion of the spool.

Abstract: A spool valve (1) includes: a sleeve (10) extending in an axial direction thereof, including an inlet port (11) and an outlet port for working fluid; a spool (20) movably housed in the sleeve (10) in the axial direction; a biasing device (30) including a spring (31) as a biasing member configured to press a base end (20a) of the spool (20) toward a tip end (20b) of the spool (20); and a pressure detecting port (56) for the working fluid, opening toward the tip end (20b) of the spool (20). The outlet port (12) is constituted of slits (16), and the slits (16) are arranged at intervals in the circumferential direction of the sleeve (10) and extended in the axial direction.

Abstract: A pump system includes a triple-gear pump which pressurizes a fluid using three gears; an outlet flow path which guides the fluid from a first pressure-increasing portion to an outlet; a first flow path which guides the fluid from the first pressure-increasing portion to a second pressure-increasing portion; a second flow path which guides the fluid from the second pressure-increasing portion to the outlet flow path; a third flow path connected to the first flow path and the second flow path; a first valve device provided in the first flow path; a second valve device provided in the second flow path, and a control device which controls the first valve device. When the first pressure-increasing portion and the second pressure-increasing portion are switched from a parallel state to a series state, the control device causes the first valve device to open after the second valve device is closed.

Abstract: A pump system includes a triple-gear pump which pressurizes a fluid using three gears; an outlet flow path which guides the fluid from a first pressure-increasing portion to an outlet; a first flow path which guides the fluid from the first pressure-increasing portion to a second pressure-increasing portion; a second flow path which guides the fluid from the second pressure-increasing portion to the outlet flow path; a third flow path connected to the first flow path and the second flow path; a first valve device provided in the first flow path; a second valve device provided in the second flow path, and a control device which controls the first valve device. When the first pressure-increasing portion and the second pressure-increasing portion are switched from a parallel state to a series state, the control device causes the first valve device to open after the second valve device is closed.

Abstract: A fluid supply system includes: a centrifugal pump; a starting pump that is connected to the centrifugal pump in series, is provided downstream of the centrifugal pump, and has a discharge flow rate less than that of the centrifugal pump; a measuring valve that is provided downstream of the centrifugal pump and the starting pump, measures an amount of fluid discharged from the centrifugal pump or the starting pump, and discharges the fluid to a downstream each time the fluid reaches a predetermined flow amount; a differential pressure valve that is provided downstream of the centrifugal pump and the starting pump, and is driven based on a differential pressure between an upstream pressure and a downstream pressure of the measuring valve; and a flow rate control valve that is provided downstream of the centrifugal pump and upstream of the differential pressure valve and has a valve opening speed that is set slower than that of the differential pressure valve.

Abstract: A gear pump is comprised of a driving gear, a first driven gear and second driven gears mutually in mesh; a housing accommodating them and defining a flow path including a first suction port, a second suction port, a first pressure port and a second pressure port; a floating comprising a thrust face bearing a floating force exerted by fluids and first, second and third pressure-receiving faces respectively oriented in a direction opposed to the thrust face; a first pressurizing chamber having fluid connection with the first pressure port or the second pressure port to exert pressure on the first pressure-receiving face; a second pressurizing chamber having fluid connection with the first suction port to exert pressure on the second pressure-receiving face; and a third pressurizing chamber having fluid connection with the second suction port to exert pressure on the third pressure-receiving face.

Abstract: A gear pump is comprised of a driving gear, a first driven gear and second driven gears mutually in mesh; a housing accommodating them and defining a flow path including a first suction port, a second suction port, a first pressure port and a second pressure port; a floating comprising a thrust face bearing a floating force exerted by fluids and first, second and third pressure-receiving faces respectively oriented in a direction opposed to the thrust face; a first pressurizing chamber having fluid connection with the first pressure port or the second pressure port to exert pressure on the first pressure-receiving face; a second pressurizing chamber having fluid connection with the first suction port to exert pressure on the second pressure-receiving face; and a third pressurizing chamber having fluid connection with the second suction port to exert pressure on the third pressure-receiving face.

Abstract: A fuel system includes a fuel pump formed of a constant-volume pump for changing a discharge flow rate in conjunction with a variation in a speed of revolution of a drive shaft, a boost pump disposed upstream from the fuel pump and formed of a constant-volume pump of which a discharge flow rate per unit of revolution of a drive shaft is greater than that of the fuel pump, a single electric motor rotationally driving the drive shaft of the fuel pump and the drive shaft of the boost pump in a state in which the speeds of revolution thereof are equal to each other, a return flow channel connecting an upstream side and a downstream side of the boost pump, and a relief valve disposed in the return flow channel and opened when an internal pressure of the return flow channel is greater than a reference pressure.

Abstract: A fuel system includes a fuel pump formed of a constant-volume pump for changing a discharge flow rate in conjunction with a variation in a speed of revolution of a drive shaft, a boost pump disposed upstream from the fuel pump and formed of a constant-volume pump of which a discharge flow rate per unit of revolution of a drive shaft is greater than that of the fuel pump, a single electric motor rotationally driving the drive shaft of the fuel pump and the drive shaft of the boost pump in a state in which the speeds of revolution thereof are equal to each other, a return flow channel connecting an upstream side and a downstream side of the boost pump, and a relief valve disposed in the return flow channel and opened when an internal pressure of the return flow channel is greater than a reference pressure.

Abstract: In a double gear pump that is provided with a drive gear; two driven gears that are oppositely arranged with the drive gear therebetween, a first bearing that supports a drive shaft of the drive gear; and a second and a third bearings that support rotating shafts of the two driven gears, the bearing length of the first bearing is formed shorter than the bearing lengths of the second and third bearings. According to the present invention, it is possible to provide a double gear pump that is capable of easily and reliably reducing the bearing loss of a bearing that support a gear.

Abstract: In a double gear pump that is provided with a drive gear; two driven gears that are oppositely arranged with the drive gear therebetween, a first bearing that supports a drive shaft of the drive gear; and a second and a third bearings that support rotating shafts of the two driven gears, the bearing length of the first bearing is formed shorter than the bearing lengths of the second and third bearings. According to the present invention, it is possible to provide a double gear pump that is capable of easily and reliably reducing the bearing loss of a bearing that support a gear.

Abstract: A three-gear type gear pump or double gear pump wherein the first driven gear and the second driven gear are opposed to one another with the driving gear disposed between them, wherein the number of teeth of the driving gear is greater than the number of teeth of each of the first driven gear and the second driven gear.

Abstract: A three-gear type gear pump or double gear pump wherein the first driven gear and the second driven gear are opposed to one another with the driving gear disposed between them, wherein the number of teeth of the driving gear is greater than the number of teeth of each of the first driven gear and the second driven gear.