Jidosha Kiki Co., Ltd.

Bosch Braking Systems Co. Ltd.

Yuuichi Kimura

Shigeyuki Miyazawa

Tadaaki Fujii

Kazuyoshi Uchino

Hiroto Iwata

Masaaki Kogure

Takashi Shimo

Tatsufumi Yamura

A variable displacement pump includes pump bodies, a cam ring, first and second fluid pressure chambers, a rotor, a driving shaft, a pump chamber, a compression coil spring, a metering restrictor portion, and a control valve. A plunger damper is formed to incorporate the compression coil spring such that a distal end of the plunger damper abuts against a side portion of the cam ring in the second fluid pressure chamber. A small hole constituting the metering restrictor portion is formed at such a position that it is opened/closed by a slidable motion of the plunger damper during a swing motion of the cam ring, and such that it is partitioned from the second fluid pressure chamber, so that an opening area of the small hole changes in an interlocking manner to the swing motion of the cam ring.

Variable displacement pump

A cam case 23 is provided which swingably support a cam ring 34 fitted to a rotor 33 having a vane 33a so as to form a pump chamber 36 from the outer surface such that the cam ring 34 is swingably supported by using a swingable pin 35 disposed in the axial direction as a fulcrum, the cam case 23 serving as an intermediate body. Pump bodies are disposed on the two ends of the cam case in the axial direction. Moreover, a front body 21 and a rear body 22 for rotatively supporting a rotational shaft 40 of the rotor are disposed. A valve hole 75 for forming a relief valve 74 for relieving fluid pressure in the discharge portion of the pump to a suction portion of the pump when the fluid pressure has been made to be not lower than a predetermined level is a blind hole having an end which is, in the rear body, opened in a joining surface with the cam case. Valve elements 74a received in the valve hole are anchored by the joining surface of the cam case.

A cam ring for forming a pump chamber on the outer periphery of a rotor which is rotatable in a body is arranged movably, and is urged in a direction in which the volume of the pump chamber is made maximum. Sealing means are interposed in an annular gap space on the outer periphery of the cam ring between the cam ring and the body, thereby forming first and second fluid-pressure chambers for allowing the cam ring to undergo displacement by moving. A spool-type changeover valve is provided which is operated in accordance with the discharge flow rate of the pressure fluid from the pump chamber to control the fluid pressure supplied to the first and second fluid-pressure chambers. The fluid pressure on the downstream side of a metering orifice 29 provided in a pump discharge-side passage 28 is introduced into the second fluid-pressure chamber for imparting moving displacement in the direction in which the volume of the pump chamber is made maximum, through a passage 37 via a second valve chamber 32b. It is possible to control the swinging of the cam ring, and to prevent fluctuations in the flow rate and a decline in the flow rate on the discharge side of the pump.

Variable displacement pump having a changeover value for a pressure

Growing community of inventors

Saitama, Japan

Yuuichi Kimura