Abstract: A steering assist system for a hybrid vehicle capable of being driven by both of an engine and a drive motor, including a first assist portion and a second assist portion configured to assist a steering force respectively utilizing the engine and an electric motor each as a drive source, wherein the steering force is assisted only by the second assist portion in a motor-driven state in which the vehicle is driven only by the drive motor, and wherein the steering assist system is configured to, upon occurrence of a failure of the second assist portion in the motor-driven state, drive the engine, execute assist switching from an assist by the second assist portion to an assist by the first assist portion, and gradually increase, in the assist switching, an assist force by the first assist portion up to a set assist force when the vehicle is being steered.

Abstract: A hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (P) connected to a main flow path (2) and a tank port (T) connected to a tank flow path (3), a first working port arrangement having a first left working port (L1) connected to a first left working flow path (4) and a first right working port (R1) connected to a first right working flow path (5), a variable first left orifice (A2L) connected to the main flow path (2) and to the first left working flow path (4), a variable first right orifice (A2R) connected to the main flow path (2) and to the first right working flow path (5), a variable second left orifice (A3L) connected to the first left working flow path (4) and to the tank flow path (3), a variable second right orifice (A3R) connected to the first right working flow path (5) and to the tank flow path (3), and a second working port arrangement having a second left working port (12) connected to a second left working flow path (9) and a second right work

Abstract: A hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (P) connected to a main flow path (5) and a tank port (T) connected to a tank flow path (6), a working port arrangement having a left working port (L) connected to a left working flow path (7) and a right working port (R) connected to a right working flow path (8), a bridge arrangement (14) of variable neutral open orifices, said bridge arrangement (14) comprising a first left orifice (A2L) connected to a main flow path (5) and to the left working flow path (7), a first right orifice (A2R) connected to a main flow path (5) and to the right working flow path (8), a second left orifice (A3L) connected to the left working flow path (7) and to the tank flow path (6), and a second right orifice (A3R) connected to the right working flow path (8) and to the tank flow path (6). Such a steering unit has a good steering behavior but can function as a closed-center solution.

Abstract: An emergency in-lane steering assist system for use during a braking event comprises an object sensor for detecting the presence of an object in front of a motor vehicle and providing data from which the distance from the object to the motor vehicle is determined and a velocity sensor providing data from which the forward velocity of the motor vehicle is determined. A controller in communication with the object sensor and the velocity sensor calculates a Time to Contact (TTC) with the detected object and a steering system is responsive at least in part to operation by the controller. If the calculated TTC is less than a predetermined TTC, the controller provides a lateral steering input during the braking event to reduce the linear distance traveled by the motor vehicle relative to a predetermined path in the lane.

Abstract: A hydraulic steering arrangement (1) is provided comprising a static steering unit (2) and an adjustable pressure source (3) connected to a pressure port (4) of said steering unit (2) and having a load sensing port (21). Such a steering unit should enable a fast reaction of the steering unit. To this end said pressure source (3) is a dynamic pressure source having an orifice (Adyn) outputting hydraulic fluid to said load sensing port (21), a load sensing line (22) connecting said load sensing port (21) and a low pressure port (11), a control valve (24) being arranged in said load sensing line (22) between said load sensing port (21) and said low pressure port (11), said control valve (24) being actuated by a control pressure within said steering unit (2) and throttling a flow through said load sensing line (22) depending on said control pressure.

Abstract: The motor-driven power steering may include a user selection unit, a driving motor unit, and a control unit that includes a basic current map creating driving torque according to a vehicle speed for controlling the driving motor unit by using a vehicle speed and steering torque input through CAN communication and a sub-current map obtained by reducing the basic current map at a predetermined reduction ratio, creates adjustment torque corresponding to an adjustment signal adjusted by the user selection unit by using the sub-current map, and includes a sub-functional logic adjusting driving torque created by the basic current map by the created adjustment torque, a driving torque compensation map compensating adjustment driving torque adjusted by the sub-functional logic in accordance with the traveling state of a vehicle, and a driving logic that controls the driving motor unit by using compensation driving torque compensated by the driving torque compensation map.

Abstract: The working vehicle may include a working apparatus in which an attachment is attachably mounted, a flow rate limitation setting means to set the maximum flow rate of hydraulic oil, an engine revolution sensor, a cam plate angle sensor, a valve opening degree sensor to measure a present flow rate of the hydraulic oil, a switching valve to switch between a single acting type and a double acting type, a display, a main controller to connect the flow rate limitation setting means, the engine revolution sensor, the cam plate angle sensor, the valve opening degree sensor, the switching valve, and the display apparatus. The maximum flow rate and the present flow rate, which are set by the flow rate limitation setting means, may be simultaneously displayed on the display apparatus.

Abstract: A hydraulic-power steering system is provided. A power-steering valve controls and varies a level of steering assist. A magnetic actuator varies torsional stiffness of the valve to change torque and produce a sufficient amount of the torque to generate full assist. A first valve is operatively connected to a steering pump and allows the full assist at a relatively low steering torque and through which flow from the steering pump is directed. A second valve is operatively connected to the steering pump. Current is applied to a solenoid valve that allows an increasing amount of the flow to be directed through the second valve in response to an input signal of increasing vehicle speed above a threshold value and closes in response to a signal identifying any of a plurality of advanced steering functions.

Abstract: A method for controlling a speed difference between speed of wheels of a front axle and speed of wheels of a rear axle of a four-wheel drive vehicle. The method: determines an initial speed difference set point based on the speed of the vehicle; determines one or more intermediate speed difference set points based on one or more operational parameters of the vehicle; modulates the initial speed difference set point based on the intermediate speed difference set points to obtain a final speed difference set point; measures the speed difference and compares the measured speed difference with the final speed difference set point; and controls the measured speed difference, so that the measured speed difference reaches the final speed difference set point.

Abstract: An apparatus (10) for use in turning steerable vehicle wheels (14, 16) includes a hydraulic power steering motor (12). A pump (26) is connected in fluid communication with the hydraulic power steering motor (12) by a supply conduit (30). A continuously variable transmission (50) is connected with the engine (52) of the vehicle and with the pump (26). The continuously variable transmission (50) is operable under the influence of force transmitted from the engine (52) to drive the pump at a first speed when the flow of fluid from the pump (26) is at a first level. The continuously variable transmission (50) drives the pump (26) at a second speed different than the first speed when the flow of fluid from the pump is at a second level different than the first level.

Abstract: An electric power steering apparatus comprises a charge-discharge circuit capable of configuring a circuit for charging an auxiliary power supply and a circuit for discharging a battery and the auxiliary power supply as well as configuring a discharge-preference circuit which enables only the discharge of the auxiliary power supply while avoiding the charge thereof. In the apparatus, a control circuit performs a power latch operation of carrying on control till the end of a predetermined period of time following an operation of turning off an ignition key, and also causes the charge-discharge circuit to configure the discharge-preference circuit thereby enabling steering assist accompanied by the discharge of the auxiliary power supply.

Abstract: In a vehicle including a traction engine designed to drive wheels through a driveline that includes an upstream portion which is connected to the engine and a downstream portion which is permanently connected to the drive wheels, the power steering system includes a hydraulic circuit including a fluid tank and a steering actuator. The power steering system further includes a first pump which is driven by mechanical power from the downstream portion of the driveline, and a second pump which is driven by an electric motor. The first and second pumps are arranged in parallel between the fluid tank and the steering actuator and are capable of supplying fluid from the fluid tank to the steering actuator at the same time.

Abstract: An apparatus (10) for use in turning steerable vehicle wheels (14, 16) includes a hydraulic power steering motor (12). A pump (26) having an outlet port (28) is connected in fluid communication with the power steering motor (12) and operable to supply hydraulic fluid to the power steering motor (12). A continuously variable transmission (50) is connected with the engine of the vehicle and the pump (26). The continuously variable transmission (50) is operable to drive the pump (26) at a first speed when the pressure at the outlet port (28) is at a first pressure. The continuously variable transmission (50) is operable to drive the pump (26) at a second speed when the pressure at the outlet port (28) is at a second pressure different than the first pressure. The first speed at which the pump (26) is driven is greater than the second speed.

Abstract: A method is provided for recognizing the fatigue of a driver of a vehicle. In the method a torque variable representing the torque applied to the steering wheel by the driver is detected, and the presence of fatigue of the driver is detected on the basis of the torque variable.

Abstract: A power steering system comprises a hydraulic circuit, a pump arranged to pressurize hydraulic fluid and valve means arranged to control the flow of pressurized fluid in the hydraulic circuit to control the steering force provided by the system. The system further comprises a motor arranged to drive the pump and control means arranged to control operation of the motor, and the control means is arranged to determine the position of the motor from a plurality of parameters by means of a position determining algorithm.

Abstract: An alignment changing control device that includes: a motor drive section which adjusts electrical power supplied to a motor of the electric actuator according to an operation command and, when receiving an operation inhibiting signal, limits or stops supplying the electrical power to the motor; a motor temperature estimating section for calculating an estimated temperature of the motor from at least a current supplied to the motor, an outside air temperature and a vehicle speed, based on heat balance relationship; and a comparator which transmits the operation inhibiting signal to the motor drive section when the estimated temperature of the motor calculated by the motor temperature estimating section is higher than a predetermined temperature, which is equal to or lower than an operation allowable temperature of the motor.

Abstract: A power assist steering system for a vehicle, especially for a truck or commercial vehicle, is disclosed that includes a mechanical engine-driven power steering pump that pumps hydraulic fluid to a power steering unit, and an electrical pump adapted to pump hydraulic fluid so as to optimize a power steering flow to the power steering unit and to minimize internal pump flow.

Abstract: A method of steering a vehicle with a hydraulic steering system is disclosed. A first control signal is sent to a pilot valve. The pilot valve is operated to direct pilot fluid to a main valve in response to the first control signal. The main valve is opened to a first position in response to the pilot fluid. Fluid is directed through the main valve to a first actuator. Resistance to actuation of the first actuator is detected. The detected resistance is compared to a threshold resistance. A second control signal is sent to the pilot valve when the detected resistance exceeds the threshold resistance. The pilot valve is operated to direct pilot fluid to the main valve in response to the second control signal. The main valve is opened to a second position in response to the pilot fluid. Fluid is directed through the main valve to the first actuator and a second actuator.

Abstract: A steering system is provided for a work vehicle comprising articulated first and second vehicle sections. The steering system comprises a controller adapted to: determine from a speed-request signal if a requested steering speed requested for the first vehicle section relative to the second vehicle section about an articulation axis toward an end of an end region of a position range of the first vehicle section is at least a predetermined steering speed; determine from a position signal if the first vehicle section is positioned in the end region of the position range; and, if the requested steering speed is at least the predetermined steering speed and the first vehicle section is positioned in the end region, signal that an actual steering speed of the first vehicle section be lower than the requested steering speed. An associated method is disclosed.

Abstract: In a power steering system, the steering state of wheels is detected based on the steering speed to judge as to whether the steering state is in turning of the steering wheel or holding of steering speed is the steering wheels. At the time of the steering operation state, the control is executed so that a difference between a torque command value to an electric motor and the actual torque thereof will become smaller. Also, at the time of the holding operation state, the control is executed so that a difference between the revolution speed of the electric motor and a revolution-speed command value thereto will become smaller.

Abstract: A steering system for a machine having at least one steerable traction device is disclosed. The steering system may have a steering actuator operatively connected to the at least one steerable traction device, and a travel speed sensor configured to generate a signal indicative of a travel speed of the machine. The steering mechanism may also have an operator input device having a deadzone. The deadzone may vary in response to the signal. The steering system may also have a controller in communication with the steering actuator, the operator input device, and the travel speed sensor. The controller may be configured to affect operation of the steering actuator in response to operation of the operator input device only when the operation of the operator input device deviates from the deadzone.

Abstract: There is provided a power steering system including an electric motor for generating a steering force in response to an command value, and a controller for generating the command value to the electric motor. Here, the controller generates the command value in correspondence with steering state of wheels, thereby controlling torque or rotation number of the electric motor.

Abstract: A rollover avoidance system for changing the damping characteristics of suspension dampers at each wheel of a vehicle so as to mitigate the potential for vehicle rollover. The system includes a plurality of vehicle parameter sensors for measuring vehicle parameters and providing vehicle parameter signals. The system also includes a controller for generating a damper suspension command signal for each damper using the vehicle parameter signals. The controller considers a roll control factor representing a rollover condition of the vehicle and a yaw stability control factor representing a yaw condition of the vehicle to set the damping of the dampers to mitigate the potential for vehicle rollover.

Abstract: In a hydraulic power steering apparatus, hydraulic pressure for generating steering assist power is varied by varying opening of a variable throttle portion by movement of a spool. The spool is disposed in a provisional origin by driving a stepping motor in one direction according to a number of steps for setting provisional origin from a position at a time of start of control, and the number of steps at a time of completing of the driving is set to a provisional origin for calculation. In a return to origin permission state where the spool is disposed in a provisional origin and the number of steps from the provisional origin for calculation is zero, a number of steps at a time when the driving of the stepping motor according to a number of steps obtained by subtracting the number of steps for setting provisional origin from a number of steps for setting origin is completed is set to an origin for calculation, and the movement of the spool is stopped at the origin with a stopper.

Abstract: A hydraulic steering system for a work machine may include a first steering actuator having a first and a second chamber. In addition, the steering system may include a second steering actuator having a third and a fourth chamber. A multi-position directional valve may include at least one low power position and at least one high power position. The low power position may be configured to direct fluid only to the first chamber during a low power turn to extend the first steering actuator. The high power position may be configured to direct fluid to the first chamber and the third chamber during a high power turn to retract the second steering actuator.

Abstract: The invention generally relates to an improvement of conventional Hydraulically Power Assisted Steering system (HPAS-system) arranged to supply a steering assist force to the steering assembly of a vehicle as a response to a torque applied by a driver to the steering wheel. In such HPAS-systems a certain drivers torque always results in a certain assist force. The invention therefore discloses a valve that can be actuated to dynamically alter the steering assist force produced by the HPAS-system. This makes it possible to dynamically adjust the assist force so that an appropriate force may be delivered to fit the specific driving scenario.

Abstract: An apparatus (10) for use in turning steerable vehicle wheels (14, 16) includes a hydraulic power steering motor (12). A pump (26) is operable to supply hydraulic fluid to the power steering motor (12). A gearset (50) is connected with the engine of the vehicle and the pump (26). The gearset (50) is operable to drive the pump at a first speed during turning of the steerable vehicle wheels (14, 16) at relatively low vehicle speeds. The gearset (50) is operable drive the pump at a second speed during turning of the steerable vehicle wheels at relatively high vehicle speeds. The second speed which is less than the first speed. The gearset is a differential gear mechanism.

Abstract: A retroactive device as part of a hydraulic servo-steering system that also includes a hydraulic servo-valve device, the retroactive device comprising an arrangement for hydraulically producing a restoring moment into a central position that produces the restoring moment as a function of the pressure differential between a pressure side and a low-pressure side. The system has at least one valve arrangement that, when pressure is applied in the central position of the servo-valve, is adapted to produce a pressure differential between the external and internal chambers of the valve. The valve arrangement is disposed hydraulically in series with the retroactive device.

Abstract: Provided are a hydraulic pump 7, an electromagnetic flow rate control valve 2 that controls the flow rate of hydraulic oil supplied from the hydraulic pump 7 to a power steering device PS, and a pressure compensating valve 4 that maintains a fixed pressure difference between upstream and downstream sides of the electromagnetic flow rate control valve 2 and bypasses an excess flow rate. The electromagnetic flow rate control valve 2 maintains a predetermined initial opening when a control current is zero, while an opening of the electromagnetic flow rate control valve decreases to become a minimum opening when the control current increases from zero, and the opening gradually becomes larger toward a maximum opening when a predetermined control current is exceeded.

Abstract: A flow controlling apparatus for a power steering system includes a variable throttle mechanism installed in the pump to change the flow rate of discharged oil from the pump to a hydraulic device; a linear solenoid mechanism controlling the variable throttle mechanism by a predetermined energizing current; a spool feeding back the excess discharged oil to a bypass passage of the pump in accordance with a differential pressure between the upstream and downstream sides of the variable throttle mechanism when the excess fluid exceeds a predetermined value; and an ECU controlling the energized current to change the transition process in accordance with a steering angular velocity of the steering wheel.

Abstract: An apparatus (10) for helping to turn steerable wheels (12) of a vehicle comprises a hydraulic power-assisted steering gear (16). An electric motor (92) actuates the steering gear (16). A pump (84) supplies the steering gear (16) with hydraulic fluid. A vehicle speed sensor (102) senses vehicle speed and provides a vehicle speed signal. A controller (104) is responsive to the vehicle speed signal for controlling the pump (84). The controller (104) activates the pump (84) to supply hydraulic fluid to the steering gear (16) when the vehicle speed signal indicates a vehicle speed below a predetermined value and the controller (104) deactivating the pump (84) when the vehicle speed signal indicates a vehicle speed above the predetermined value.

Abstract: Steering gearbox mechanism for automotive vehicles that allows feeding the hydraulic fluid control mechanism of said steering mechanism with pressurized hydraulic fluid, depending on the vehicle's working conditions. Thus, when the vehicle is stopped or running at a very low speed, the hydraulic fluid is sent to the steering mechanism for assistance. At this condition, the user may carry out the driving maneuvers effortlessly. Moreover, when the vehicle is running at high speeds, the assistance is disconnected, by means of deviating the pressurized fluid back to the fluid reservoir, allowing the engine to continue impelling the pump but without assisting the steering mechanism since at those speeds the user can carry out any maneuver without any effort.

Abstract: A vehicle speed response type power steering system, wherein, when a vehicle is moving at a relatively slow speed, a relatively large auxiliary power is generated to enable a driver to easily adjust a steering of the vehicle with relatively little steering power, and when a vehicle is moving at a high speed, a relatively small auxiliary power is generated to prevent an abrupt turn in order to stabilize the steering operation of the vehicle, such that formation of appropriate auxiliary power in response to a vehicle speed allows a driver to carry out an easy and safe steering manipulation.

Abstract: 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 I1 in accordance with a steering angle supplied from a steering angle sensor, a current instruction value I2 in 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.

Abstract: 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 14, a current instruction value I2 in accordance with a steering angular velocity and current instruction values I5, I6 in 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.

Abstract: To generate a damping force in a steering damper only upon an unintentionally caused handle action when it is truly necessary to restrain the turning of the handle, according to whether the cause of a handle action is intentional or unintentional. A rotation type steering damper is provided coaxially with a steering shaft, and the generation of a damping force or zero damping force is selected through a changeover by a variable valve provided in a bypass passage for communication between a right liquid chamber and a left liquid chamber of the steering damper.

Abstract: A rear wheel steering angle control apparatus is provided with a rear wheel steering angle determining unit and a rear wheel steering mechanism so as to determine a steering angle ratio based upon vehicle speed and perform a rear wheel steering angle control. An alerting unit alerts that the output of the rear wheel steering mechanism is beyond a predetermined allowable range when an observing unit detects a control condition being abnormal and releases the alert when the output of the rear wheel steering mechanism is within the predetermined allowable range.

Abstract: The invention concerns a method of steering a vehicle, particularly an articulated vehicle, in which a valve element of a main valve is moved so that it releases or closes connections between a supply connection arrangement and a working connection arrangement in dependence of a steering direction and a steering angle. To improve the steering comfort, the movement speed of the valve element is controlled.

Abstract: An apparatus (10) for turning steerable wheels of a vehicle comprises a housing (12). A rack bar (54) is movable longitudinally relative to the housing (12) for turning the steerable wheels. A pinion gear (68) is located within the housing (12). Teeth (76) of the pinion gear (68) are in meshing engagement with teeth of the rack bar (54). The apparatus (10) also comprises a hydraulic motor (60) for moving the rack bar (54) relative to the housing (12). A valve assembly (98), responsive to rotation of a steering wheel (94) for directing fluid to the hydraulic motor (60), has an actuated position and an unactuated position. The apparatus (10) further comprises a mechanism (156) for dampening longitudinal oscillations of the rack bar (54). The mechanism (156) comprises a yoke bearing (158) which contacts the rack bar (54) with a variable pressure that is dependent upon a velocity of rack bar (54) relative to the housing (12).

Abstract: 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 8, a steering valve 9 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 IT based on a steering torque and a solenoid current instruction value IS defining a standby flow rate.

Abstract: A steering system for an automotive vehicle having two front wheels and two rear wheels is provided.

Abstract: 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 8, a steering valve 9 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 IT based on a steering torque and a solenoid current instruction value IS defining a standby flow rate.

Abstract: A hydraulic power steering apparatus for a vehicle is provided with a main control valve in which a valve opening degree is controlled on the basis of a relative movement between an input shaft interlocking with a steering wheel and an output shaft interlocking with a steering mechanism for turning a steered wheel, a power cylinder mechanism generating a steering assist force, a pump apparatus discharging a fixed flow amount of working oil, a first flow passage including a supply passage communicated with the main control valve, and a control unit controlling an assist control valve. The main control valve controls a supply amount of the working oil in the first flow passage to the power steering apparatus, and the assist control valve controlling a flow amount of a part of the working oil discharged from the pump apparatus is controlled to a set valve opening degree set on the basis of a vehicle speed and an oil pressure of the working oil in the first flow passage, by the control unit.

Abstract: A motor is stopped when a steering angular speed is not greater than a stop threshold VS and a motor electric current value Im is kept within a motor stop range &Dgr;I for a predetermined time period. The value of a steering torque increases as the motor electric current value Im increases. Therefore, the motor can assuredly be stopped when the steering torque is small. Further, when the motor is off, the sensitivity for motor actuation with respect to a change in the steering angle is set higher as the value of the steering angle increases.

Abstract: A hydraulic power steering apparatus for a vehicle is provided with a main control valve in which a valve opening degree is controlled on the basis of a relative movement between an input shaft interlocking with a steering wheel and an output shaft interlocking with a steering mechanism for turning a steered wheel, a power cylinder mechanism generating a steering assist force, a pump apparatus discharging a fixed flow amount of working oil, a first flow passage including a supply passage communicated with the main control valve, and a control unit controlling an assist control valve. The main control valve controls a supply amount of the working oil in the first flow passage to the power steering apparatus, and the assist control valve controlling a flow amount of a part of the working oil discharged from the pump apparatus 1 is controlled to a set valve opening degree set on the basis of a vehicle speed and an oil pressure of the working oil in the first flow passage, by the control unit.

Abstract: 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 8, a steering valve 9 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 IT based on a steering torque and a solenoid current instruction value IS defining a standby flow rate.

Abstract: A power steering apparatus is provided, which is adapted to generate a steering assist force by a hydraulic pressure of a pump driven by an electric motor. The apparatus includes: a vehicle speed sensor for sensing a vehicle speed; and a control circuit for switching a control mode between an assist mode in which a first voltage V1 is applied to the electric motor and a standby mode in which no voltage or a second voltage V2 lower than the first voltage V1 is applied to the electric motor. The control circuit includes a threshold computation circuit for determining a threshold of a predetermined physical quantity (motor current or steering angle) as a function of the vehicle speed V sensed by the vehicle sensor, and comparison means for comparing a level of the physical quantity with the threshold determined by the threshold computation circuit. The control mode is switched from the assist mode to the standby mode on the basis of a comparison result obtained by the comparison means.

Abstract: A fluid control system (10) for a vehicle power steering mechanism having a manually driven steering member and a fluid driven driving member (16) operatively connected to steering means of the vehicle by which steerage of the vehicle is achieved, the control system (10) including a first valve (12) for metering pressurised fluid flow to the fluid operated driving member (16) in response to the force required to move the steering means when operating the manually driven steering member, the first valve (12) including at least two independent metering valve means (170, 171) each of which are simultaneously operated by the steering member to meter fluid flow to and/or from the fluid operated driving member (16) at a predefined rate, at least one of the metering valve means (170, 171) communicating independently to a drain via a second valve (14), the second valve (14) being arranged to selectively connect and disconnect said at least one of said valve means (170, 171) to the drain in response to vehicle speed.

Abstract: An apparatus for use in a vehicle to control a flow of fluid to a power steering motor includes inner and outer valve members (40 and 42) which are disposed in a housing (44) and are rotatable relative to each other to control fluid flow to a power steering motor (31). A force transmitting assembly (114) is provided to resist relative rotation between the inner and outer valve members (40 and 42) with a force which varies as a function of variations in force applied against the force transmitting assembly. An actuator member (130) is provided to apply force against the force transmitting assembly (114). A power steering resistance control system (110) includes a coil (128) which provides a magnetic field which acts on the actuator member (130).

Abstract: A rotary slide valve (1) for the power steering of motor vehicles contains a rotary distributor (4) in a valve bore (5) of a valve housing (2), which distributor is connected with a valve inlet member (23). A control bushing (7) is rotatably guided over a small angle in an axial bore (6) of the rotary distributor (4). The control bushing (7) is fixedly connected to prevent relative rotation, with a valve outlet member (18). A centering device (31) is disposed between the rotary distributor (4) and the valve outlet member (18), and contains two parts which can be rotated in respect to each other, and at least one ball (37) situated between the two parts. The one part of the centering device (31) is fixedly connected with a reaction piston (32) and fixedly connected with the rotary distributor (4) against relative rotation, but is axially displaceable.