Kayaba Industry Company, Ltd.

Masashi Takai

Noboru Shimizu

Naoto Shima

Katsuhiro Suzuki

Tsunefumi Arita

Shinichi Hagidaira

Norimasa Amano

Fumihide Kozuma

Yoshiyuki Tsukada

Ryouichi Nagasaka

Tsunofumi Arita

Tatsuo Chiba

Tadao Hasegawa

A power steering system capable of giving a driver no discomfort even when an incoming current instruction value sharply decreases. The power steering system comprises a controller C for determining a solenoid current instruction value SI on the basis of a current instruction value Iin accordance with a steering angle supplied from a steering angle sensor, a current instruction value Iin accordance with a steering angular velocity, and a current instruction value in accordance with a vehicle speed. The controller C comprises a delay control section for reducing the rate of decrease only when the incoming current instruction value sharply decreases and outputting the resulting current instruction value.

Power steering system

Provision of a power steering system capable of giving a driver no discomfort during high-speed travel. A controller calculates or stores a current instruction value Iin accordance with a steering angle supplied from a steering angle sensor and a current instruction value Iin accordance with a steering angular velocity; performs multiplication of the steering angle base current instruction value Iand the steering angular velocity base current instruction value Iby current instruction values IIset based on a vehicle speed, respectively; applies current instruction values IIin accordance with the vehicle speed serving as limit values to the corresponding steering angle base and steering angular velocity base current instruction values resulting from the multiplication; selects a larger value of the two current instruction values below the limit values; and determines the selected value as a solenoid current instruction value SI.

A power steering system capable of preventing an unnecessary standby flow produced in high speed travel. A controller C determines a basic current instruction value Id based on a current instruction value I1 in accordance with a steering angle detected by a steering angle sensor, a current instruction value Iin accordance with a steering angular velocity and current instruction values I, Iin accordance with a vehicle speed, and adds a standby current instruction value Is to the basic current instruction value Id, and outputs the resultant value of the addition as a solenoid current instruction value SI, and changes the standby current instruction value Is on the basis of the vehicle speed.

Provision of a power steering system which is capable of preventing a delay in response for outputting a solenoid current instruction value SI. A controller C stores a table of basic current instruction values I corresponding to combinations of steering angles and steering angular velocities. The controller C obtains a basic current instruction value I from the table, and multiplies the obtained basic current instruction value I by a current instruction value I determined on the basis of a vehicle speed, and then determines the multiplied value as a solenoid current instruction value SI.

For an energy-saving type control, a value of a control low rate QP controlled by a flow control valve V is closer to a value of a flow rate required by an output side such as a power cylinder a steering valve or the like, to suppress a driving torque of a pump P. An excitation current I of a solenoid SOL is specified on the basis of a solenoid current instruction value I based on a steering torque and a solenoid current instruction value I defining a standby flow rate.

Power steering

For an energy-saving type control, a value of a control low rate QP controlled by a flow control valve V is closer to a value of a flow rate required by an output side such as a power cylinder , a steering valve or the like, to suppress a driving torque of a pump P. An excitation current I of a solenoid SOL is specified on the basis of a solenoid current instruction value I based on a steering torque and a solenoid current instruction value I defining a standby flow rate.

A power steering system with which no deterioration in steering feeling occurs when a control flow of working fluid changes. A valve mechanism V is made up of a power cylinder control valve CV for controlling a control flow Q and distributively supplying it to a power cylinder C and a bypass control valve BV connected in parallel with the cylinder control valve CV. The bypass control valve BV is normally closed, but while the control flow Q is increasing over a range of from a minimum flow Q.sub.1 to a maximum flow Q.sub.2 available for generating assist force the bypass control valve opens and returns a part of the control flow Q to a tank so that the pressure difference between the pressure chambers of the power cylinder C rises gently and the driver does not experience a disconcerting feeling such as one of the steering wheel suddenly being taken over.

An object of the present invention is to provide a power steering apparatus in which its neutral rigidity can be raised by applying a preset force and which is superior in its assembly performance and productivity. To attain this object, first supporting portions are formed in a pair of spring members disposed across the input shaft, and second supporting portions are formed in the input shaft so as to oppose the first supporting portions. When the input shaft and the output shaft are rotated relative to each other so that the balls or rollers are about to slip out of the first and second supporting portions, the balls or rollers roll and move while deflecting the spring members.

Power steering apparatus

A power steering device capable of facilitating assembling thereof and eliminating a variation in elastic force acting on an input shaft of the power steering device. Leaf spring structures each of which includes a first leaf spring and a second leaf spring are arranged. The first leaf spring includes a spring-side support section constituted by a V- or U-shaped groove, a pair of rolling surface sections arranged so as to be contiguous to the spring-side support section and outwardly extend from both ends of the spring-side support section, a pair of support leg sections each arranged so as to be contiguous to each of the rolling surface sections and outwardly extend therefrom, and a pair of holding sections each arranged so as to be contiguous to each of the support leg sections and outwardly extend therefrom. The holding sections each are pressedly contacted with press contact surfaces or side surfaces of a spring receiving chamber, resulting in the first leaf spring being securely held. The second leaf spring acts to exhibit elastic force required for forcing balls or rollers against an input shaft from a rear surface of the first leaf spring.

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Seki, Japan

Masashi Takai