US 5,293,954 A · Power steering system

Abstract

A power steering control valve including relatively rotatable inner and outer valve members. A power steering resistance control system resists relative rotation between the inner and outer valve members with a force which varies as a function of variations in vehicle speed. The power steering resistance control system includes a force transmitting member which is disposed adjacent to one end of an outer valve member. A spring force is applied against the force transmitting member urging it in a first direction along the axis of rotation of the valve member. Fluid pressure is applied against the force transmitting member to urge it in the first direction. A speed responsive control unit is operable to vary the fluid pressure applied against the force transmitting member as a function of variations in vehicle speed. The power steering resistance control system also includes a means for preventing an increase in the resistance to relative movement between the valve members as the vehicle speed increases when there is no relative movement between the valve members.

Claims15

Dependent claims

An apparatus comprising:

first and second valve members which are movable relative to each other to port fluid to a vehicle power steering motor;
means for increasing the resistance to relative movement between said first and second valve members as vehicle speed increases, including:
a force transmitting member connected with said first valve member and movable toward and away from said second valve member for applying a force to resist relative movement between said first and second valve members;
means defining a fluid pressure chamber for receiving fluid, the pressure of which acts on said force transmitting member, said first and second valve members including means for conducting fluid to said fluid pressure chamber;
and
means for increasing the fluid pressure in said fluid pressure chamber as vehicle speed increases and there is relative movement between said first and second valve members;
and
means for preventing an increase in the pressure in said fluid pressure chamber as vehicle speed increases when there is no relative movement between said first and second valve members.

5 more elements

An apparatus comprising:

first and second valve members which are movable relative to each other to port fluid to a vehicle power steering motor;
a force transmitting member connected with said first valve member and movable toward and away from said second valve member for applying a force to resist relative movement between said first and second valve members;
means defining a fluid pressure chamber for receiving fluid, the pressure of which acts on said force transmitting member;
a first valve for increasing the pressure in said fluid pressure chamber as a function of vehicle speed to increase the resistance to relative movement between said first and second valve members with an increase in vehicle speed;
and
a second valve for venting said chamber when there is no steering demand to prevent an increase in resistance to relative movement between said first and second valve members with an increase in vehicle speed and no steering demand.

3 more elements

Dependencies are inferred from the claim text.

Power steering system

Life of this patent

Power steering system

Life of this patent

Abstract

Claims15