Nissan Motor Company Limited

Koh Uchida

Takashi Kurihara

Makoto Miyoshi

Makato Miyoshi

Yoshikazu Takahashi

Naoki Yuzuriha

Naoki Norimatsu

Katsuhiro Suda

Hirohide Kai

Takayuki Bitou

Taisuke Ueda

Toru Inoue

Hideyuki Kita

Yohei Koike

Nariaki Tazawa

A working fluid medium temperature control system comprises an actuator operable on a working fluid medium, a pump for the working fluid medium, a fluid passage structure for the working fluid medium, an electric motor drivingly connected to the pump, and a control unit for the electric motor, the control unit including an inverter and an inverter controller. The inverter and the electric motor are integrated in such a way that the inverter is in heat transfer communication with the electric motor. The fluid passage structure is in heat transfer communication with the inverter.

Working fluid medium temperature control system and method

A power steering device for a motor vehicle whereby when the vehicle is under a high or middle speed movement, the slide torque is controlled to a relatively low constant level irrespective of the turning of the steering wheel. The device includes a hydraulic pump for producing a hydraulic pressure; a power cylinder powered by the hydraulic pressure for producing a force to assist the steering job; a hydraulic valve for controlling the hydraulic pressure supplied to the power cylinder, the hydraulic valve including a valve shaft and a valve body; a chattering protection seal associated with the hydraulic valve to assure a concentric rotation of the valve shaft relative to the valve body with an assistance of hydraulic pressure applied thereto; and an electronically controlled solenoid valve. The electronically controlled solenoid valve applies when the vehicle is at a standstill or under a low speed movement, the chattering protection seal with a hydraulic pressure which is varied as a steering wheel is turned, and applies, when the vehicle is under a high or middle speed movement, the chattering protection seal with a hydraulic pressure which is controlled to a relatively low constant level even when the steering wheel is turned.

Hydraulic valve device for automotive power steering gear

A control valve includes valve elements relatively displaceable in response to a predetermined variable (e.g., a steering torque) to define therebetween two parallel fluid flow paths connected between a fluid source and a fluid reservoir to produce pressure difference in a power cylinder. The control valve comprises a bypass path provided with a variable flow orifice that has an orifice area variable in response to said predetermined variable and an externally controlled variable flow orifice valve that has an orifice area variable in response to a second predetermined variable which is different from the first predetermined variable.

Variable assist power steering system

A variable assist power steering system comprises a control valve including valve elements relatively displaceable in response to a steering torque to define therebetween two parallel fluid flow paths connected between the fluid source (10) and the fluid reservoir to produce pressure difference in the power cylinder in response to the steering torque. The control valve includes a plurality of bypass paths, each arranged in parallel to one of plurality of serially arranged variable flow orifices forming the two flow paths and each provided with an externally controlled variable flow orifice valve which is operable responsive to a vehicle speed.

Variable assist power steering system with varying power assist

A variable assist power steering system employing a fluid distributor circuit of the open center type is disclosed. The fluid distributor circuit includes two parallel fluid flow paths connected to both chambers of a power cylinder respectively to produce a pressure differential between the both cylinder chambers in response to steering torque. For modulating the valve characteristics, two additional variable flow restrictors are arranged in series with two main variable flow restrictors and two bypass paths are arranged to bypass the main variable flow restrictors, respectively. The bypass paths are provided with variable flow orifice valves, respectively, which valves are controlled in response to a turning direction of a steering wheel and also to some external signal, such as vehicle speed.

Hydraulic system for variable assist power steering system

A control valve includes valve elements relatively displaceable in response to a predetermined variable (e.g., a steering torque) to define therebetween two parallel fluid flow paths connected between a fluid source and a fluid reservoir to produce pressure difference in a power cylinder. The control valve comprises a bypass path provided with variable flow orifice means for providing a throttle of fluid flow of the bypass path in response to the predetermined variable and an externally controlled variable flow orifice valve that has an orifice area variable in response to a second predetermined variable which is different from the first predetermined variable.

Hydraulic fluid circuit for variable assist power steering system

A control valve includes valve elements relatively displaceable in response to a steering torque to define therebetween two parallel fluid flow paths connected between a fluid source and a fluid reservoir to produce pressure difference in a power cylinder. The control valve comprises a bypass path including a first externally controlled variable flow orifice and a variable flow orifice variable with steering torque and a first externally controlled variable flow orifice valve which are connected in series, a second externally controlled variable flow orifice valve, and a second variable flow orifice variable with steering torque. The bypass path is arranged in parallel with a portion of the two parallel fluid paths, the second externally controlled variable flow orifice valve is arranged in parallel with another portion of the parallel fluid paths, and the second variable flow orifice is arranged in series in the remaining portion of the parallel fluid paths.

Variable assist power steering system with varying power assist with

A steering control valve for a power steering system for a vehicle includes a valve structure which defines a plurality of variable flow orifices as steering input torque is applied thereby creating pressure differential acting on fluid motor. A solenoid operated variable flow orifice valve is operable in response to a control factor, such as vehicle speed, other than the steering input torque defines a variable flow orifice connected in series with one of the plurality of variable flow orifices.

Steering control valve for variable power assist steering system

A control valve includes valve elements relatively displaceable in response to a predetermined variable (e.g., a steering torque) to define therebetween two parallel fluid flow paths connected between a fluid source and a fluid reservoir to produce pressure different in a power cylinder. The control valve a variable flow orifice that is arranged in series with regard to one of variable flow orifices of the parallel fluid flow paths, and a bypass path including has an externally controlled variable flow orifice valve that has an orifice area variable in response to a second predetermined variable which is different from the first predetermined variable.

Vehicle speed responsive variable assist power steering system

A power assist steering system comprises a control valve which defines a fluid flow distributor circuit which includes two parallel first and second fluid flow paths connected between the hydraulic fluid source and the fluid reservoir. Inflow control variable flow orifices are arranged in series with two auxiliary variable flow orifices, respectively, which are disposed downstream with regard to the power cylinder, and the outflow control variable flow orifices are arranged in series with another two auxiliary variable flow orifices which are disposed downstream with regard to the power cylinder.

Operating noise-free fluid flow distributor circuit for variable assist

A power steering control valve can activate not only a power assist steering system but also a rear wheel steering system. The control valve includes valve elements relatively displaceable in response to a steering input torque to define therebetween parallel first and second fluid flow paths between an oil pump and a fluid reservoir to produce a first pressure difference in a front power cylinder in response to the steering torque. The valve elements define therebetween variable flow orifice means for producing a second pressure difference in a rear wheel power cylinder in response to the steering torque. The control valve also includes an externally controlled variable flow orifice valve. This orifice valve is arranged with respect to the variable flow orifice means such that it increases fluid flow passing therethrough in response to a second predetermined variable, such as a vehicle speed, to decrease the second pressure difference in the rear wheel power cylinder.

Hydraulic fluid pressure control system for use with power assist

A rotary type power steering control valve comprises a groove arrangement which includes two first grooves spaced longitudinally along a longitudinal axis, and a second longtudinally extending groove which has one circumferential side overlapping the two first grooves to define two variable flow orifices. The direction of fluid is reversed by the second longitudinally extending groove so that both of the variable flow orifices are arranged in series.

Rotary control valve for power assist steering system

A circuit arrangement is proposed whereby a bypass flow coming out of one portion of a fluid flow distributor circuit of a power steering system during clockwise turning of a steering wheel and another bypass flow coming out another portion of the fluid flow distributor circuit during counterclockwise turning of the steering wheel are directed toward a fluid reservoir after passing through an externally controlled variable flow orifice.

A flow control passage fluidly interconnects an output flow passage and a return flow passage to bypass a control valve. A control valve operation modifying variable orifice is disposed in and partly defines the flow control passage. The control valve operation modifying variable orifice is variable in flow area in response to at least one of vehicle control factors other than steering torque. A fixed flow area orifice is disposed in and partly defines the flow control passasge at a location downstream of the control valve operation modifying variable orifice. The control valve has a plurality of steering torque responsive variable orifices and bypass passage means for bypassing at least one of the steering torque responsive variable orifices. A differential pressure passage provides communication between the upstream and downstream sides of the fixed flow area orifice. An actuator is disposed in and partly defines the differential pressure passage. The actuator has a pressure movable part which is movable in response to variation of differential pressure produced by the fixed flow area orifice. The bypass passage means includes a differential pressure responsive variable orifice operatively connected to the pressure movable part of the actuator and variable in flow area in response to movement of the pressure movable part of the actuator.

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Sagamihara, Japan

Koh Uchida