Power steering system with auxiliary power capability

Abstract

A vehicular power steering system including a primary hydraulic circuit for operating the steered wheels and a secondary hydraulic circuit for operating auxiliary equipment such as an implement or the like which may be attached to the vehicle. The system includes a fluid controller for controlling the flow of pressurized fluid from a power pump to the primary or steering circuit and the implement or secondary circuit. The fluid controller includes a valve mechanism which is constructed and arranged to provide the primary hydraulic circuit with pressurized fluid in the amount necessary to produce the desired steering maneuver while furnishing the secondary hydraulic circuit with the excess pressurized fluid supplied by the power pump. Thus the requirements of the primary hydraulic circuit may be always satisfied and have priority over the requirements of the secondary circuit in all modes of operation. .Iadd.

We claim:  .[.1. A fluid controller comprising a housing having a fluid inlet port, a pair of working ports, a return port and an auxiliary port formed therein, and valve means for selectively interconnecting said ports including a valve element movable in one direction from a neutral position to an operating position and in another direction from said neutral position to another operating position, said valve means, in the neutral position of said valve element, establishing a flow path between siad inlet port and said auxiliary port and, during movement of said valve element toward either of said operating positions of said valve element maintaining said flow path between said inlet port and said auxiliary port and establishing a restricted flow path between said inlet port and one of said working ports and establishing a flow path between the other of said working ports and said return port, said valve means being effective, as said valve element moves progressively from said neutral position toward one of said working ports, to progressively increase the restriction between said inlet port and said auxiliary port and to progressively decrease the restriction between the inlet port and the one of said working ports to which it is connected..]. .[.2. A fluid controller as defined in claim 1 and including an operating shaft journalled for rotation on said housing, and means interconnecting said operating shaft and said valve element for moving said valve element from said neutral position to one of said operating positions as said operating shaft is rotated in one direction and for moving said valve element from said neutral position to the other of said operating positions as said operating shaft is rotated in the opposite direction..]. .[.3. The fluid controller as defined in which said valve element is axially arranged and shifts axially as it moves from said neutral position toward either of said operating positions..]. .[.4. The fluid controller of claim 1 wherein the valve element completely blocks fluid flow from said inlet port to said auxiliary port at each of the operating positions thereof and provides an unrestricted flow path to the respective one of said working ports while providing an unrestricted flow path from the other of said working ports to said return port..]. .[.5. A fluid controller comprising a housing, said housing including a fluid inlet, first and second working ports, a fluid return port and an auxiliary port, a valve movably located within said housing and having a neutral position communicating the inlet to the auxiliary port and blocking the inlet from the first and second working ports, said valve having first and second operative positions communicating said inlet with the first and second working ports respectively and said valve blocking communication with the second and first working ports at the first and second operative positions of the valve respectively and progressively restricting communication from the inlet to the auxiliary port and progressively increasing communication between the inlet and the first or second working ports and establishing communication between the other of said working ports and said return port as said valve is moved from said neutral position; spring means normally biasing said valve to the neutral position, and a valve actuator operatively associated with said valve for moving said valve from the neutral position to the operative positions..]. .Iadd. 6. A fluid controller for actuating a vehicle power steering motor in opposite directions comprising a housing including a fluid inlet adapted to be connected with a pressurized fluid supply pump, a fluid return port adapted to be connected to a fluid reservoir, and first and second working ports, valve means located within said housing, said valve means having a neutral condition blocking the inlet from said first and second working ports and blocking said first and second working ports from said return port, said valve means having first and second operative positions communicating said inlet with the first or second working port, respectively, and blocking communication with the second or first working port, respectively, said valve means progressively increasing communication between the inlet and the first or second working port and establishing communication between the other of said working ports and said return port as said valve means moves from said neutral position, means normally biasing said valve means to neutral and a valve actuator operatively associated with said valve means for moving said valve means from neutral, said valve actuator comprising a rotatable input shaft, a follow-up mechanism for returning said valve means to neutral upon termination of rotation of said input shaft, said housing having an auxiliary port adapted to lead to auxiliary apparatus, means coacting between the valve means and the housing to divide fluid flow from said inlet into a pair of flow paths and to recombine said fluid flow from said pair of flow paths and direct said recombined fluid to said auxiliary port when said valve means is in neutral and to restrict fluid flow through both flow paths during movement of said valve means toward either of said first and second operative positions, and said follow-up mechanism including a rotatable member connected with said valve means and said biasing means and which is actuated upon cessation of turning of said input shaft which returns the valve means to neutral, said power steering motor and said auxiliary port being in parallel fluid circuits controlled by said valve means, and said valve means in said fluid controller being unaffected by fluid pressure in the power steering motor or the auxiliary apparatus so that pressure changes therein are not transmitted to the rotatable input shaft and said follow-up mechanism returns the valve means to neutral independently of the fluid pressure in the power steering motor or in the auxiliary apparatus. .Iaddend..Iadd. 7. A fluid controller for actuating a vehicle power steering motor in opposite directions, said fluid controller having a housing including a fluid inlet adapted to be connected with a pressurized fluid supply pump, a fluid return port adapted to be connected to a fluid reservoir, and first and second working ports adapted to be connected to respective opposite portions of said vehicle power steering motor, a metering unit in said housing, a valve spool located within said housing for porting fluid to said metering unit and porting fluid from said metering unit to one of said working ports, said valve spool having a neutral condition blocking the inlet from said first and second working ports and blocking said first and second working ports from said return port, said valve spool having first and second operative positions communicating said inlet with said metering unit and with the first or second working port, respectively, and blocking communication with the second or first working port, respectively, said valve spool progressively increasing communication between the inlet and the metering unit and the first or second working port and establishing communication between the other of said working ports and said return port as said valve spool is moved from said neutral position, spring means normally biasing said valve spool to neutral and a valve actuator operatively associated with said valve spool for moving said valve spool from neutral, said valve actuator comprising a rotatable input shaft, said spring means comprising a torsion bar connected at one end to said shaft, a follow-up mechanism for returning said valve spool to neutral upon termination of rotation of said input shaft, said housing having an auxiliary port adapted to lead to auxiliary apparatus, means coacting between the valve spool and the housing to divide fluid flow from said inlet into a pair of flow paths and to recombine said fluid flow from said pair of paths and direct said recombined fluid to the auxiliary port when said valve spool is in neutral and to restrict fluid flow through both flow paths during movement of said valve spool toward either of said first and second operative positions, and said follow-up mechanism including a rotatable member connected with said valve spool and said torsion bar and which rotates upon flow to said vehicle steering motor and which returns the valve spool to neutral, the other end of said torsion bar being connected to said rotatable member of said follow-up mechanism, said metering unit and said auxiliary port being in parallel fluid circuits controlled by said valve spool, and said valve spool in said fluid controller being unaffected by fluid pressure in the vehicle steering motor or the auxiliary apparatus so that pressure changes therein are not transmitted to the rotatable input shaft and said follow-up mechanism returns the valve to neutral independently of the fluid pressure in the vehicle steering motor or in the auxiliary apparatus. .Iaddend..Iadd. 8. A fluid controller as defined in claim 7 in which said valve spool is axially moveable and shifts axially as it moves from said neutral position toward either of said operative positions. .Iaddend..Iadd. 9. A fluid controller as defined in claim 7 wherein the valve spool completely blocks fluid flow from said inlet port to said auxiliary port at each of the operative positions thereof and provides an unrestricted flow path to the respective one of said working ports while providing an unrestricted flow path from the other of said working ports to said return port. .Iaddend.