Hitachi, Ltd.

Unisia Jecs Corporation

Hitachi Unisia Automotive, Ltd.

Toshimitsu Sakaki

Masakazu Kurata

Mitsuo Sasaki

Chiharu Nakazawa

Tadaharu Yokota

Toru Takahashi

Yasuhito Nakakuki

Ayumu Miyajima

Isamu Tsubono

Takaomi Nishigaito

Yoshitaka Sugiyama

Tatsuo Matsumura

Tetsuo Abe

Kaname Kidokoro

An oil pump including a first housing having a rotation shaft insertion hole, a cam ring, a pump element, a rotation shaft rotatably extending through the rotation shaft insertion hole, a second housing disposed on the cam ring, wherein the cam ring is placed in a position relative to the rotation shaft insertion hole of the first housing by using a jig, and the cam ring includes a clamped portion that is clamped by a cam ring holding device, while the first housing and the second housing are fixed to each other after placing the cam ring in the position relative to the rotation shaft insertion hole by using the jig. Alternatively, the oil pump including a fixing means for fixing the cam ring to the pump body instead of the clamped portion.

Oil pump and method of assembling the oil pump

A power steering system includes a hydraulic power cylinder having a first and a second hydraulic chambers, for assisting a steering force of a steering mechanism, a first and a second oil passages respectively connected to the first and second hydraulic chambers, a reversible pump discharging operating oil and providing oil pressure to the hydraulic power cylinder through the first and second oil passages, and a motor connected to the reversible pump and rotating the reversible pump in normal and reverse directions. A steering load detection unit detects a steering load of a steering wheel for steering of the steered road wheels, and a motor control unit outputs a control signal to the motor to bring an actual oil pressure generated by the reversible pump closer to a desired oil pressure determined based on the detected steering load. A discharge amount per rotation of the reversible pump is smaller than or equal to 5 cc.

Power steering system

In a power steering system comprising a power cylinder for assisting a steering power of a steering mechanism, a hydraulic pump for supplying a hydraulic pressure to the power cylinder, a first oil passage and a second oil passage connecting the power cylinder and the hydraulic pump respectively, a motor for driving the hydraulic pump, and power steering control means for calculating a command value to the motor based on the steering torque, a flow rate of the working oil supplied from a high-pressure side oil passage to a low-pressure side oil passage is restrained at the transition from the end of the steering state (lock end) of the steering mechanism to the returning. The flow-rate restraint increasingly corrects a driving current of the motor in the steering direction or limits the flow rate of the working oil.

An oil pump is provided which includes a cam ring made of a material having a first line expansion coefficient, a pump element rotatably disposed in the cam ring and smaller in an axial length than the cam ring, a first housing member disposed on one of axially opposite sides of the cam ring and made of a material having a second line expansion coefficient larger than the first line expansion coefficient, and a second housing member disposed on the other of the axially opposite sides of the cam ring and made of a material having a third line expansion coefficient than the first line expansion coefficient.

Oil pump adapted to prevent leakage without using sealing member

A first fluid passage extends from a first outlet/inlet port of a hydraulic pump to a first work chamber of a power cylinder, and a second fluid passage extends from a second outlet/inlet port of the pump to a second work chamber of the power cylinder. A switch system switches the role of the first and second outlet/inlet ports in accordance with a turning direction of a steering wheel. Flow control mechanisms are respectively incorporated with the first and second fluid passages, so that a controlled flow of hydraulic fluid from the hydraulic pump to the first or second work chamber and vice versa are appropriately carried out thereby providing the driver with a comfortable steering feeling. A bypass arrangement may be provided between the first and second fluid passages to deal with a residual pressure that would be remained in the first or second work chamber when the hydraulic pump is under inoperative condition.

Power steering device

A brushless DC motor control system is arranged to control a command current indicative of a current to be supplied to the brushless motor on the basis of an estimated phase angle and an actual phase angle to control a current supplied to the brushless motor on the basis of an estimated phase angle and an actual phase angle, and to execute at least one of an estimated phase angle returning processing for returning the estimated phase angle and a current lowering processing for lowering a command current, when the estimated phase angle advances relative to the actual phase angle.

Brushless motor control system

A power steering system is provided which comprises a bypass conduit connecting between first and second communication conduits and having bypass conduit ports. A pair of valves disposed in the bypass conduit for selectively opening and closing the bypass conduit ports in response to the pressure fluid from the pressure source. The valves are adapted to provide communication between the first and second communication conduits when the hydraulic pressure source is inoperative.

Growing community of inventors

Kanagawa, Japan

Toshimitsu Sakaki