Trw Limited

Jim L Rau

Laurence L Miller

Raymon L Goff

Ronald L LaHue

Emil M Shtarkman

Frederick D Venable

Mark R Kinder

William T Rabe

Gerald K Oxley

Hollis N White, Jr

Charles A Barker

An electric steering system (10) includes a power source (34) and an electric motor (28) which provides an auxiliary steering force in response to a large capacity capacitor (C1) being selectively connected to the power source (34), for charging the large capacity capacitor (C1), and to the motor (28), for discharging the large capacity capacitor (C1) to drive the electric motor (28) for providing the auxiliary steering force.

Electric steering system

A universal joint (10) for a steering gear input shaft (11) includes a yoke (12), a bolt (14) movable into an installed position in the yoke, and a spring clip (22) for locking the bolt in its installed position in the yoke. The spring clip (22) moves with the bolt (14) when the bolt is moved into its installed position in the yoke (12), and has first and second portions (202, 212). The first and second portions (202, 212) of the spring clip (22) have locking positions in which the first portion (202) engages the bolt (14) and the second portion (212) interlocks with the yoke (12) to block movement of the bolt out of the yoke. The second portion (212) of the spring clip (22) moves resiliently into its locking position to interlock with the yoke (12) upon movement of the bolt (14) into its installed position in the yoke (12).

Fail-safe universal joint connection

A power steering system includes a bypass valve assembly which bypasses fluid from a main conduit connected with a power steering pump and motor. The bypass valve assembly is urged toward an open condition, bypassing fluid from the main conduit, with a force which varies as a function of the fluid pressure drop across an orifice in the main conduit. The bypass valve assembly is urged toward a closed condition by a spring. In addition a pressure responsive pilot valve assembly opens to communicate the fluid pressure in the main conduit to the bypass valve to urge the bypass valve assembly toward the closed condition. This decreases the rate at which fluid from the power steering pump is bypassed to thereby increase the amount of fluid available for actuation of the power steering motor.

Apparatus for use in a power steering system

A system for controlling fluid flow from a source to a steering motor and one or more auxiliary motors comprises a priority valve and a steering controller. The priority valve has a housing that includes an inlet port connected to the source, a priority flow outlet port, an auxiliary flow outlet port, and a pilot port. A biasing spring urges the priority valve spool toward a priority position directing all flow from the inlet port to the priority port. The priority valve includes a pilot flow conduit directing a pilot flow of fluid through an orifice to the pilot port. Pressure upstream of the pilot flow orifice acts on the priority valve spool in opposition to the spring, and pressure downstream of the pilot flow orifice acts on the valve spool in addition to the spring. The steering controller has a load sense cavity communicating with a load sense port, and a neutral vent orifice which, when the steering controller is in neutral, communicates said load sense cavity with a return port for allowing a pilot flow of fluid from the pilot port of the priority valve to flow through said steering controller to the reservoir. Upon activation from its neutral position, the steering controller substantially restricts flow through the neutral vent orifice to the reservoir before its main flow control orifice opens.

Hydrostatic load sense steering system

In a hydrostatic load sense vehicle steering system, fluid flow from a source is used by a hydrostatic steering controller to effect steering of the vehicle. The controller has a metering unit and a control valve which, in response to a steering effort, moves away from a neutral position to an operating condition in which it (i) establishes a main flow control orifice which directs fluid from the source to the metering unit and (ii) directs metered fluid to a steering motor. A fluid actuator controls the flow of fluid from the source to the hydrostatic steering controller. A pilot fluid circuit directs a pilot flow of fluid to the controller which is used to control the operation of the fluid actuator. In the controller, the control valve directs the pilot fluid to a reservoir when there is no steering. The system is designed to come to a standby condition in which the amount of pilot fluid being directed to the controller is high enough that it can be used to satisfy a range of low demand steering maneuvers. In providing the pilot flow, the system develops hydraulic biasing forces on the components of the fluid actuator. The hydraulic biasing forces help the system respond to a high demand steering maneuver to increase rapidly the amount of fluid which is made available for effecting steering.

Hybrid load-sense vehicle hydrostatic steering system

An apparatus for controlling fluid flow to a steering motor and an auxiliary apparatus is capable of smoothly changing between conditions in which it directs relatively small and relatively large flows of fluid to the auxiliary apparatus. The apparatus includes a priority valve assembly having a valve member positioned in accordance with variations in the demand for steering fluid. A land on the valve member cooperates with a fixed valve surface to form a variable size orifice through which fluid flows to a steering controller. A second land on the valve member cooperates with a fixed valve surface to form a variable size main auxiliary flow control orifice through which all of the fluid flow to the auxiliary apparatus is directed during relatively low fluid flow rates to the auxiliary apparatus. A third land on the valve member cooperates with a fixed valve surface to form a second variable size flow control orifice through which additional fluid flow is directed to the auxiliary apparatus during relatively high fluid flow rates to the auxiliary apparatus.

Fluid flow control apparatus

An improved power steering apparatus includes a variable displacement pump. During a steering operation, a flow control valve effects operation of a motor assembly to vary the displacement of the pump as a function of variations in the demand for power steering fluid. Upon initiation of a steering operation, the displacement of the pump must be quickly increased to enable it to satisfy the impending demand for power steering fluid. Therefore upon initial rotation of a steering wheel, a steering controller restricts a flow of fluid to operate the motor assembly independently of the flow control valve. The displacement of the pump can thus increase before the flow control valve can be actuated during an initial portion of a steering operation.

Steering control apparatus

A fluid flow control system includes a priority valve which is controlled by a pressure differential applied across the valve, and which directs priority flow to a steering circuit and excess flow to an auxiliary circuit. The system insures that during steering, a relatively high pressure differential is required to shift the priority valve away from a priority steering position in which all fluid flow is delivered to the steering circuit. It also insures that when the flow to the steering circuit is sufficient to satisfy the steering demand, and the valve is also directing flow to the auxiliary circuit, a lower pressure differential is required to shift the valve in a direction for increasing the flow to the auxiliary circuit.

Apparatus with staged pressure differential for controlling fluid flow

An improved power steering control apparatus includes a power steering motor having a piston rod which extends through one end of the motor cylinder. This results in the rod end of the piston having a smaller working area than the head end of the piston. In order to equalize the fluid pressure forces on opposite sides of the piston when the motor is in an inactive condition, a power steering control valve vents both sides of the piston to atmospheric pressure when the control valve is in a neutral or unactuated condition. Three conduits are connected with the control valve; a supply conduit which conducts fluid from a pump to the control valve to effect operation of the motor upon actuation of the control valve; a return conduit through which fluid is returned to a reservoir when the control valve is in the neutral condition; and a vent conduit which connects the control valve and opposite sides of the motor cylinder piston directly with the reservoir and atmospheric pressure when the control valve is in the neutral condition.

Power steering control apparatus

A hdydrostatic load sense vehicle steering system which directs fluid from a source to a hydrostatic steering circuit that includes a steering controller, and to an auxiliary circuit. Fluid control means responds to fluid pressures in a pilot circuit to direct priority flow to the steering circuit and excess flow to the auxiliary circuit. The pilot circuit includes a first pilot conduit that communicates with a load sense port of the steering controller. The steering controller controls fluid pressures in the pilot circuit in accordance with the condition of the steering circuit. A second pilot conduit communicates a pressure signal in accordance with the condition of the auxiliary circuit to the fluid control means. The second pilot conduit also communicates through a bleed orifice with the load sense port of the steering controller. When the controller is in neutral, it directs the pilot fluid from its load sense port to a reservoir. When the controller moves away from neutral, it restricts pilot flow to the reservoir to provide a pressure signal in the pilot circuit that indicates a need for flow and pressure in the steering circuit.

Load sense hydrostatic vehicle steering system

A torque absorbing coupling for a hydrostatic steering system which a hydrostatic steering controller responds to operation of a steering wheel to direct flow from a source to a steering motor. The coupling minimizes the possibility of a high reaction torque being felt by the operator who turns the steering wheel more rapidly than the system can deliver flow and pressure to the controller to levels which are sufficient to effect steering as demanded by the operator. The coupling is provided between the steering wheel and the controller's metering unit, and operates to absorb reaction torques over a time interval, and thereby delays transmission of those reaction torques to the operator over that time interval, to provide the system with an additional time interval to increase flow and pressure to the levels demanded.

Hydrostatic steering system with delayed input torque column

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 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.

Power steering system with auxiliary power capability

A drive assembly includes a casing containing a planetary gear assembly. A speed control arrangement is provided in association with the planetary gear assembly to vary the speed of rotation of an output member relative to the speed of rotation of an input member. The speed control arrangement includes a first disc pack which is engaged under the influence of a spring to prevent relative rotation between a ring gear and a planet carrier. A second disc pack is also engageable under the influence of a spring to prevent rotation of the ring gear relative to the casing. Hydraulic motors are selectively operable to release the disc packs against the influence of the associated springs. In the event of a failure in the source of hydraulic fluid, both disc packs are engaged with a resulting braking of rotation of the driven wheel. A secondary or towing clutch is selectively disengageable to release the output member and wheel for rotation, even though both of the disc packs are engaged. The springs cooperate with the disc packs in such a manner that wear is minimized. Compact construction of the drive assembly is promoted by eliminating the use of bearings to hold the ring gear against sidewise movement. The compact construction of the drive assembly is also promoted by forming the ring gear with a pair of annular side sections which have the same inside diameter and which extend axially outwardly from opposite sides of the ring gear into engagement with disc packs.

Drive assembly

An improved control apparatus is utilized in a vehicle which has a single pump for supplying fluid to effect turning movement of steerable wheels and operation of an auxiliary apparatus. The control apparatus includes a housing in which a piston is movable in a cylinder under the influence of fluid pressure to effect turning movement of the steerable wheels. A valve assembly is disposed in the same housing. The valve assembly is operable between an unactuated condition in which fluid flow from a pump is directed to the auxiliary apparatus and either one of two actuated conditions in which fluid flow from the pump is directed to an end portion of the cylinder to effect movement of the piston and turning of the vehicle wheels. The valve assembly includes a rotatable sleeve member which is disposed in the valve chamber and defines a plurality of ports disposed in a circular array. A rotatable valve member is disposed within the sleeve member and cooperates with the circular array of ports to direct fluid under pressure from the pump to either the auxiliary apparatus or to the cylinder in which the piston is disposed to effect turning movement of the vehicle wheels.

Control apparatus

A vehicle steering system comprises a source of fluid, a hydraulic steering motor actuatable to effect vehicle steering, and a steering control valve in fluid communication with the source of fluid and with the steering motor. The steering control valve is operable to direct fluid from the source of fluid to the steering motor. A metering mechanism is connected in fluid communication with the steering control valve and the steering motor. The metering mechanism is manually operable in accordance with the operator's demand for steering, and a hydraulic system is responsive to demand for steering fluid by the metering means to increase the output flow of the fluid from the source of fluid to the metering means at a pressure sufficient only to effect steering action against a variable load.

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Lafayette, IN, United States of America

Jim L Rau