Power steering system

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, said first and second valve members including means for conducting fluid to said fluid pressure chamber;
• means for increasing the fluid pressure in said fluid pressure chamber in response to relative movement between said first and second valve members and as vehicle speed increases;
• means for preventing an increase in the pressure in said fluid pressure chamber when the vehicle speed is below a predetermined value, said preventing means including means for venting the fluid pressure in said fluid pressure chamber when the vehicle speed is below the predetermined value;
• and
• conduit means conducting fluid from said fluid pressure chamber to reservoir, said means for increasing the pressure in said fluid pressure chamber including a valve which responds to relative movement between the first and second valve members and is located in said conduit means.

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, said first and second valve members including means for conducting fluid to said fluid pressure chamber;
• means for increasing the fluid pressure in said fluid pressure chamber in response to relative movement between said first and second valve members and as vehicle speed increases, said means for increasing the fluid pressure in said fluid pressure chamber comprising a first orifice that is moved toward a closed position in response to relative movement between said first and second valve members;
• and
• means for preventing an increase in the pressure in said fluid pressure chamber when the vehicle speed is below a predetermined value.

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 relative movement between said first and second valve members to increase the resistance to relative movement between said first and second valve members with an increase in steering demand;
• and
• a second valve for venting said chamber when the vehicle speed is below a predetermined value to prevent an increase in resistance to relative movement between said first and second valve members with an increase in steering demands, said second valve being connected in parallel with said first valve.

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 relative movement between said first and second valve members to increase the resistance to relative movement between said first and second valve members with an increase in steering demand;
• and
• a second valve for venting said chamber when the vehicle speed is below a predetermined value to prevent an increase in resistance to relative movement between said first and second valve members with an increase in steering demand, said second valve including a solenoid operated valve for increasing the fluid pressure in said fluid pressure chamber with an increase in vehicle speed, said solenoid operated valve having a first position in which the fluid pressure in said fluid pressure chamber is vented and a second position in which the fluid pressure in said fluid pressure chamber increases as a function of relative movement between said first and second valve members, said solenoid operated valve being in its first position when the vehicle speed is below the predetermined value and being in its second position when the vehicle speed exceeds the predetermined value.

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 relative movement between said first and second valve members to increase the resistance to relative movement between said first and second valve members with an increase in steering demand;
• a second valve for venting said chamber when the vehicle speed is below a predetermined value to prevent an increase in resistance to relative movement between said first and second valve members with an increase in steering demand;
• and
• a source of fluid associated with said first and second valve members;
• said first valve having a first position in which fluid is conducted from said fluid pressure chamber through said first valve and to reservoir and a second position in which fluid is blocked from flowing through said first valve, said first valve being urged to said second position by fluid pressure from said source of fluid, said first valve comprising an orifice defined by a seat and a restrictor valve, said restrictor valve being urged away from said seat by the fluid pressure in said fluid pressure chamber, and a pin engaging said restrictor valve for moving said restrictor valve toward said seat, said pin being urged into engagement with said restrictor valve by fluid pressure from said source of fluid.

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 relative movement between said first and second valve members to increase the resistance to relative movement between said first and second valve members with an increase in steering demand;
• a second valve for venting said chamber when the vehicle speed is below a predetermined value to prevent an increase in resistance to relative movement between said first and second valve members with an increase in steering demand;
• first conduit means for conducting fluid from a source of fluid to said first and second valve members;
• second conduit means for conducting fluid between said first and second valve members and the vehicle power steering motor;
• and
• third conduit means for conducting fluid from said first and second valve members to reservoir, said first and second valves controlling the pressure in at least a portion of said third conduit means.

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;
• and
• a first orifice for conducting fluid from the fluid pressure chamber that is moved toward a closed position in response to relative movement between said first and second valve members to increase the fluid pressure in said fluid pressure chamber in response to relative movement between said first and second valve members, said first orifice being urged toward an open position by the fluid pressure in said fluid pressure chamber.

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 orifice for conducting fluid from the fluid pressure chamber that is moved toward a closed position in response to relative movement between said first and second valve members to increase the fluid pressure in said fluid pressure chamber in response to relative movement between said first and second valve members, said first orifice being urged toward an open position by the fluid pressure in said fluid pressure chamber, said first orifice being defined by a seat and a valve body;
• a pin engaging said valve body for moving said valve body toward said seat;
• and
• a source of fluid associated with said first and second valve members, said pin and said valve body being urged toward said seat by fluid pressure from said source of fluid, said valve body being urged away from said seat by the fluid pressure in said fluid pressure chamber.

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 orifice for conducting fluid from the fluid pressure chamber that is moved toward a closed position in response to relative movement between said first and second valve members to increase the fluid pressure in said fluid pressure chamber in response to relative movement between said first and second valve members, said first orifice being urged toward an open position by the fluid pressure in said fluid pressure chamber;
• and
• a second orifice for venting said fluid pressure chamber when the speed of the vehicle is below a predetermined value to prevent an increase in resistance to relative movement between said first and second valve members with an increase in steering demand.