Hitachi Automotive Systems Steering, Ltd.

Hitachi Astemo Ltd.

Satoshi Muramatsu

Yukio Uchida

Norikazu Kumasaka

Masaaki Iijima

Hiroki Imanaga

Tomohiko Nakazono

Yoshiaki Kido

Yutaka Ogiwara

Masaaki Aoki

A pump device includes: a drive shaft; a pump element; a pump housing including; a pump element receiving space, first and second bearing receiving spaces, a suction passage, a discharge passage, a return passage, and a seal receiving space, a first bearing including a first lubrication groove, received within the first bearing receiving space, and supporting the drive shaft; a second bearing which includes a second lubrication groove having a sectional area that is perpendicular to the rotation axis, and that is greater than a sectional area of the first bearing that is perpendicular to the rotation axis, which is received within the second bearing receiving space, and which supports the drive shaft; and a seal member provided within the seal receiving space, and arranged to seal between the drive shaft and the pump housing.

Pump device

A variable displacement vane pump is provided. This pump includes a pump housing including, a driving shaft, a rotor, a plurality of vanes, a cam support surface, a cam ring, an intake port formed at the pump housing, a discharge port formed at the pump housing, and a cam ring control mechanism disposed at the pump housing and configured to control an eccentric amount of the cam ring with respect to the rotor. The cam support surface is formed in such a manner that a shortest distance between the cam support surface and a reference line decreases from a second confining region side toward a first confining region side, and the cam ring is formed in such a manner that a cam profile radius change rate decreases first and then increases again on the second confining region side when eccentric amount of the cam ring is maximized.

Variable displacement vane pump

A variable displacement vane pump includes a notch portion which is a flow path provided to extend from an initiating end of a discharge port towards a terminating end side of a suction port. The notch portion is formed so that a sectional area of the flow path is smaller than a sectional area of the discharge port at the initiating end thereof and that a length of the flow path in a circumferential direction is 1.5 pitches or larger. The terminating end of the suction port is a point where the vane in the suction area last overlaps the suction port. The initiating end of the discharge port is a point where the vane departed from the suction area first overlaps the discharge port. One pitch is a distance defied in the circumferential direction between adjacent vanes of the plurality of vanes.

A variable displacement vane pump and a power steering can secure a discharge flow rate when a steering wheel is turned, and restrict the discharge flow rate when the steering wheel is not turned. In the variable displacement vane pump and power steering system, a bypass line is formed. The bypass line causes a hydraulic fluid in a high pressure chamber of a control valve, which controls an eccentricity of a cam ring, to flow directly to a low pressure chamber side of the control valve. The hydraulic fluid flows directly to the low pressure chamber side of the control valve when the steering wheel is turned.

Growing community of inventors

Atsugi, Japan

Satoshi Muramatsu