Abstract: A power steering apparatus which generates a steering assist force by a hydraulic pressure generated by a pump driven by an electric motor. The power steering apparatus actuates the electric motor in its off state, on condition that a change amount of a steering angle exceeds an actuation threshold. A first actuation threshold which is to be employed when a steering wheel is operated away from a steering angle midpoint and a second actuation threshold which is to be employed when the steering wheel is operated toward the steering angle midpoint are determined in accordance with a sensed steering angle so that the sum of the first and second actuation thresholds is virtually constant.

Abstract: A power steering apparatus is provided which is adapted to generate a steering assist force by a hydraulic pressure generated by a pump driven by an electric motor. The apparatus includes: a steering angle detection section (11, S1, S4) for detecting an absolute steering angle on the basis of a steering angle midpoint and a relative steering angle; a first control section (31, S6, S8 to S10) for actuating the electric motor in response to the steering angle detection section detecting an absolute steering angle of not smaller than a first threshold value; and a second control section (31, S6, S11, S9, S10) for actuating the electric motor in response to a steering angle change becoming not smaller than a second thresold value which is smaller than the first threshold value when the absolute steering angle detection is not carried out by the steering angle detection section.

Abstract: A system assists the driver of a motor vehicle to travel within a designated driving lane defined by one or more lane boundaries. The lane boundary is sensed as the vehicle moves within the lane while monitoring the position of the vehicle relative to the lane boundary. The operation of the vehicle is then adjusted as a function of the proximity of the vehicle to the lane boundary. In one embodiment, the operation of the vehicle is affected by adjusting the functioning of the steering wheel, preferably by providing tactile feedback which causes the driver to experience a virtual change in lane elevation as the vehicle approaches the lane boundary. In the preferred embodiment, the tactile feedback causes the vehicle operator to experience the lane as having a depression with sloping sidewalls. Where the lane boundaries are defined by visual lane markers, the lane-boundary sensor preferably takes the form of a video camera to image the lane markers.

Abstract: A steering system for a motor vehicle with at least one steerable wheel, an actuator, and an auxiliary drive. The steering motion initiated by the driver of the vehicle and the motion initiated by the actuator are superimposed by the auxiliary drive to generate the steering motion of the steerable wheel. At least two steering components are computed and a control signal is generated to control the actuator by superimposing the computed steering components. The steering components are computed in parallel and independently of one another so that several functions are beneficially combined to control running behavior. This provides an improvement of running dynamics by means of steering interventions.

Abstract: A steer-by-wire steering system comprised of an electronically regulated steering positioner mounted to the steering gear of the front axle or to both front wheels of a vehicle together with an electronic steering regulator and a feedback actuator. A sensor senses the driver's selected direction from the steering wheel. Road feedback can be relayed to the driver through a feedback actuator via the steering wheel. The loss of road feel caused by the absence of the steering column, which normally strongly influences the driver's directional wish, is recreated by the feedback actuator.

Abstract: A power steering apparatus which generates a steering assist force by a hydraulic pressure of a pump driven by an electric motor. The apparatus includes: an electric current sensor for sensing an electric current flowing through the electric motor; and a control circuit for switching a voltage to be applied to the electric motor from a standby voltage to an assist voltage if the motor current is higher than a first threshold or if a change rate of the motor current is higher than a second threshold.

Abstract: An electromechanical steering actuator for a steer-by-wire application in motor vehicles. An electronic closed-loop/open-loop control system generates steering signals for a pair of electric servomotors, which act via a gear unit on a steering control element of a rack-and-pinion steering system. The closed-loop/open-loop control system includes a pair of process computers which deliver corrective signals to the servomotors via drive units. The steering actuator is divided into two diversely redundant systems including two redundant process computers, each of which delivers corrective signals via two redundant drive units to two servomotors which act on a common steering shaft.

Abstract: An electromagnetic valve for a vehicle that returns at least some of the hydraulic oil sent to a hydraulic actuator is provided. The valve has a body, two passages located at intermediate portions of two pipes, respectively, an oil path passing through the body for connecting the two passages to return the hydraulic oil from the one pipe to the other, and a valve mechanism provided within the body, the valve mechanism including a portion of the oil path and a valve body for opening and closing the oil path. Each of the two passages includes a bypass passage that does not pass through the valve mechanism. Therefore, the pressure loss of the hydraulic oil passing through the valve when the valve is closed is not significant.

Abstract: To improve a method for controlling the valve characteristic in electrohydraulic power-assisted steering systems of motor vehicles so as to prevent any impairment of the steering precision, the invention proposes to control the speed of the electric motor as a function of the current consumption such that the actual current consumption and the actual speed of the electric motor are continuously measured up to a maximum speed and compared with values for the setpoint speed at the respective value of the current consumption stored in a memory and in case of deviation a correction to the setpoint speed is effected.

Abstract: A steering system for a motor vehicle with a steering drive train having at least one steerable wheel, one actuator and one auxiliary drive. The steering wheel is operable by the driver of the vehicle as well as by mechanically configured offset devices. The offset devices have rotating input and output shafts and a predetermined offset angle between the input shaft and the output shaft. The auxiliary drive superimposes the steering motion initiated by the steering wheel and the motion initiated by the actuator to generate the steering motion of the steerable wheel. A control signal dependent on the angular offset and the rotational motion of the input shaft is computed. The actuator is then controlled dependent on at least the generated control signal to initiate the actuator initiated motion. Any structurally unavoidable nonuniformity of rotational motion is compensated for by the superimposition of an appropriate added angle.

Abstract: A system generates a brake pressure with a pump which delivers a volume into the chamber of a master brake cylinder and builds up a pressure which is used by at least one additional assembly, particularly a power-assisted steering system. The system has at least one distributing and throttling element for admitting a definable pressure to the chamber of the master brake cylinder and/or the additional assembly. The one or more distributing and throttling elements can be triggered, as a function of the brake pedal position and/or of driving condition values and/or of operating values of the vehicle, such that the chamber and/or the additional unit can be acted upon by a pump generated adjustable pressure.

Abstract: A system for controlling steering of a vehicle, including a steering device such as a steering wheel with an electric motor which assists steering of driven wheels of the vehicle, first steering control unit for controlling the motor, a CCD camera for detecting a lane condition of a road on which the vehicle travels, a yaw rate sensor for detecting motion of the vehicle, steering assist torque calculating unit for calculating a steering assist torque necessary for holding the lane, a torque sensor for detecting an actual steering torque manually applied to the steering device by the driver, and second steering control unit for calculating a torque command to be output to the first steering control unit based on the steering assist torque calculated by the steering assist torque calculating unit and the detected steering torque to control the actuator such that the torque command decreases.

Abstract: A variable assist power steering system (10) uses vehicle speed and steering wheel rate to vary the steering assist provided. A control module (30) receives vehicle speed and steering wheel rate data from sensors (24, 25) and produces a control signal for a flow control valve actuator (32) that bypasses fluid flow from the pump (22) to a reservoir (36), rather than to the steering valve (20) thereby affecting steering valve pressure which controls the rack piston (16) which changes the angle of the front vehicle wheels used for steering. The control module (30) employs first and second calibration tables (38, 40) to determine base and evasive desired actuator current values and then selects a final desired actuator current value using these values in combination with the steering wheel rate data.

Abstract: A variable assist power steering system (10) uses vehicle speed, steering wheel rate and steering valve inlet pressure to vary the steering assist provided. A control module (30) receives vehicle speed, steering wheel rate and pressure data from sensors (24, 25, 26) and produces a control signal for a flow control valve actuator (32) that bypasses fluid flow from the pump (22) to a reservoir (36), rather than to the steering valve (20) thereby affecting steering valve pressure which controls the rack piston (16) which changes the angle of the front vehicle wheels used for steering. The control module (30) employs first and second calibration tables (38, 40) to determine the control signal that ensures adequate flow while consuming the least amount of energy.

Abstract: A vehicle power steering system 10 achieves a substantially linear control relationship between an applied steering torque input T.sub.s and a resulting steering force output, that is, a powered assist to vehicle steering. The system 10 includes a reversible fluid pump 24 driven by an electric motor 26. A pair of fluid lines 20 and 22 supply pressurized fluid from the pump 24 and to the left and right ports 56 and 58 of a power cylinder 18. A pair of pressure transducers 54 and 55 sense the fluid pressures LP.sub.p and RP.sub.p in the lines 20 and 22. The pressure transducers 54 and 55 are connected to an electronic control 32 which establishes an internal closed servo control loop 322 or 342 over the powered assist to vehicle steering provided by the power cylinder 18, for example, over actuation of the motor 26. The system 10 is preferably regenerative and includes a variety of safety features which prevent system runaway and allow unencumbered manual steering in case of failure of the system.

Abstract: In a steering control system for controlling torque steer in a vehicle equipped with an electric power steering device and a torque split arrangement for individually controlling traction and/or braking force of right and left wheels, a difference in traction and/or braking force between the right and left wheels which may be produced by the torque split arrangement may give rise to torque steer depending on the geometry of the wheel suspension system of the vehicle. The control unit for the electric power steering device additionally receives an additional signal for providing an additional steering torque which is required for canceling the torque steer. Thus, the torque steer can be eliminated both economically and reliably without requiring to modify the wheel suspension system.

Abstract: To provide a particularly simple and cost effective design of a power-assisted steering unit for motor vehicles for supplying a servo-cylinder (3) with a hydraulic fluid as a function of the travelling speed and the steering rate, comprising a steering valve (1) by means of which the left and right chambers (16, 17) of the servo-cylinder (3) can be pressurized with hydraulic fluid via a pump (2) when there is a steering movement, and a bypass valve (10) connected in parallel to the servo-cylinder (3), by means of which a portion of the hydraulic fluid for pressurizing the servo-cylinder (3) that is directed past the servo-cylinder (3) is controlled, a throttling unit (26) is connected in series with the bypass valve (10). The hydraulic fluid inflow or return flow of the servo-cylinder (3) flows through this throttling unit (26) depending on the steering direction.

Abstract: The present invention provides a steering angle middle point detecting device which does not need a torque sensor, can detect a steering angle middle point with high precision without being affected by driving habits of drivers and road conditions, and can reduce memory size, and a power steering apparatus having the device. A continuous time period during which the vehicle speed is higher than a predetermined value and the steering angular velocity is lower than a predetermined value is counted, and each time the counted time has reached a predetermined time period, a detected steering angle and current are stored in a first memory.

Abstract: In a hydraulic power steering for a motor vehicle including a steering control element, a position setting means connected to the steering control element to be operated thereby, a control motor connected to the position setting means by way of a control circuit and a servo valve having control parts interconnected by a torsion bar so as to be retained in a predetermined position relative to each other, a hydraulic servo motor is operatively connected to the steered wheels of the motor vehicle and in communication with the servo valve such that hydraulic fluid is supplied to the hydraulic servo motor depending on the relative position of the control parts of the servo valve.

Abstract: In a vehicle steering control system, a manual steering input is assisted by a powered actuating steering torque which is given by K(.gamma.-t.sub.d .multidot.d .gamma./dt), where y is a detected yaw rate, K and t.sub.d are coefficients which depend on a vehicle speed, and d/dt denotes a time derivative. The detected yaw rate contributes to reducing the yaw rate of the vehicle. In particular, the coefficient t.sub.d is positive in value in a low speed range, and substantially linearly decreases with the vehicle speed, becoming negative at a certain intermediate vehicle speed. Thus, in a high speed range, when the vehicle is steered in one direction either by external disturbances or by a manual steering input, the detected yaw rate and the change rate of the yaw rate both contribute to the reduction of the yaw rate.

Abstract: A method is provided for controlling an electro-hydraulic power assist steering system including a variable-speed electric motor for pumping hydraulic fluid in the system. The method includes monitoring vehicle speed and vehicle steering wheel angle. A vehicle yaw rate is estimated using the monitored vehicle speed and monitored vehicle steering wheel angle. A control signal for setting the speed of the variable speed electric motor is compensated based based on the estimated vehicle yaw rate. Accordingly, a wide range of vehicle driving conditions are accommodated and vehicle fuel efficiency is improved.

Abstract: A vehicle power steering system uses an electric motor to drive a pump at a variable speed to provide power steering fluid at a variable flow for power assist to operator steering efforts. The system has a speed control for the electric motor which derives a command speed signal from an input load signal, the speed being switched in a switching region of the power steering fluid pressure signal between a low speed for standby operation and a higher speed to supply the power steering operation demands. The system includes sensor apparatus for providing a power steering load signal and a power steering fluid temperature sensor. The speed control derives the input load signal in the switching region by modifying the power steering load signal in response to the power steering fluid temperature sensor and a motor speed signal to compensate for temperature and speed dependent losses.

Abstract: A method and apparatus for determining a center position of the vehicular steering system includes a vehicle speed sensor, a steering sensor and a control unit. The control unit uses a strategy to determine an estimate of the steering assist force. When the steering assist force is below a force threshold and a vehicle speed is above a speed threshold, the controller filters data from the steering sensor so as to rapidly determine a precise center position for the steering system.

Abstract: A power steering apparatus for generating a steering assist force by a hydraulic pressure generated by a pump driven by an electric motor. The apparatus includes: a steering torque detecting mechanism (13) for detecting a steering torque; a steering urgency level calculating section (S5) for calculating a steering urgency level by using a time-based second-order differential value of the steering torque detected by the steering torque detecting mechanism; a target speed determining section (31, S6, S7) for determining, on the basis of the steering urgency level calculated by the steering urgency level calculating section, an assist starting speed as an initial target speed at which the electric motor (M) is actuated; and a control section (31) for controlling driving of the electric motor to equate the speed of the electric motor to the target speed determined by the target speed determining section.

Abstract: A power steering system for automobiles has a mechanical drive connection between a steering device and a steering gear arrangement for steering of vehicle wheels. The drive connection can be separated by opening a connection. In that event, the steering device is connected to the steering gear arrangement only indirectly, in that only nominal values for the steering angle of the wheels steering the vehicle are specified as a function of the adjusting travel of and/or the adjusting speed of the steering device, and the servo motor is actuated by a separate control valve arrangement.

Abstract: A method is provided for controlling an electro-hydraulic power assist steering system including a variable-speed electric motor for pumping hydraulic fluid in the system. The method includes monitoring a vehicle steering wheel angle and determining if the vehicle steering wheel angle exceeds a steering travel limit. If the steering travel limit is exceeded, the method reduces a desired motor speed to a predetermined end of travel motor speed until the steering wheel angle drops below the steering travel limit. Accordingly, energy is conserved by reducing the power consumed while the steering system is maintained at its steering travel limit.

Abstract: A method is provided for controlling an electro-hydraulic power assist steering system including a variable-speed electric motor for pumping hydraulic fluid in the system. The method includes monitoring vehicle speed, vehicle steering wheel angle, and vehicle steering wheel turning rate. A parking mode or a driving mode is selected based upon the monitored vehicle speed. The speed of the variable speed electric motor is controlled based upon the monitored vehicle steering wheel turning rate if the parking mode is selected. If the driving mode is selected, the speed of the variable speed electric motor is controlled based upon the monitored vehicle speed, vehicle steering wheel angle and vehicle steering wheel angle turning rate. Accordingly, a wide range of vehicle driving conditions are accommodated and vehicle fuel efficiency is improved.

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 method of controlling a vehicle hydraulic drive system of the type including a plurality of fluid pressure actuated wheel motors (13,15) connected in a parallel circuit with a source (17) of pressure. A flow restrictor valve (65) is disposed in a downstream conduit (27) of each of the wheel motors (13,15). The method involves determining the theoretical fluid flow for each motor, the actual fluid flow through each motor, and generating an error signal (107) which is then used to bias the restrictor valve (65) toward a flow restriction position. The disclosed method can be used to achieve steering at greater than kinematic, by scrubbing the inside front wheel, or can be used to prevent wheel slip of propulsion wheels, or can be used to prevent scrubbing of a wheel during hydrostatic braking, or can even be used to achieve vehicle steering.

Abstract: Within a valve housing of a power steering system, an object ring portion formed of a magnetic material and with ridges and troughs at its outer circumference is mounted to an input shaft, and a sensor including a Hall element is disposed in opposed relation to the object ring portion.

Abstract: A power steering system includes a fluid pump, a steering gear, a high-pressure passage connecting the fluid pump to the steering gear, and a flow control valve having a first chamber forming a part of the high-pressure passage. A metering orifice is disposed in the high-pressure passage between the first chamber and the steering gear. A feedback passage distributes feedback pressure developed in the high-pressure passage downstream of the metering orifice to a second chamber of the flow control valve. An exhaust port communicates with the first chamber. A movable valve spool is disposed in a valve bore and has one end exposed to the first chamber and opposite end exposed to the second chamber. A valve spring is disposed in the second chamber together with a slide coupled with an external actuator. One end of the valve spring is seated on the opposite end of the valve spool and opposite end thereof is seated on the slide.

Abstract: A system (10) for compensating torque steer in a vehicle power assist steering system for a front wheel drive vehicle includes an engine speed sensor (60) or a road wheel drive torque sensor (61). A torque sensor (32) senses applied steering torque. A steering assist motor (28) provides power assist to assist the vehicle operator in steering the vehicle. A controller (62) controls the power assist motor in response to the sensed applied steering torque and in response to one of the sensed engine speed or the road wheel drive torque to compensate for torque steer.

Abstract: A failure detection system for detecting an operational failure of a rack and pinion type of hydraulically controlled power steering system which employs a power cylinder to assist the driver in manipulating front wheels of the vehicle by utilizing hydraulic pressure applied to a steering gear connected to the front wheels utilizes a pressure switch for detecting a specified level of oil pressure provided by the power cylinder to be at operational failure when the vehicle speed remains higher than a specified speed for a specified time period, the pressure switch detects the specified level of hydraulic pressure.

Abstract: A vehicle steering system has a desired-value generator arrangement which is actuated by a manual steering device. The desired-value generator arrangement is connected with a hydraulic actuating unit for the steered vehicle wheels by a regulating system. A modified PD control, along with taking a control segment into account, provides a precise operation of the actuating unit analogously to the operation of the manual steering device.

Abstract: An electric power steering apparatus wherein a motor driving prohibiting means prohibits driving of a motor when a driving logic determining unit determines that a detected torque is outside a specified range, a direction in which the motor is to be driven on the basis of a motor current target value and the direction of the steering torque are opposite with respect to each other, and the direction in which the motor is to be driven on the basis of the motor current target value and the change direction detected by the torque change direction detecting unit are opposite with respect to each other, and when an abnormal current determining unit detects that a driving current is greater than a specified value.

Abstract: A motor vehicle power steering system includes a hydraulic pump, an electric motor for driving the pump, and a control unit for controlling the electric motor. The control unit includes means for controlling the power supply voltage applied to the electric motor so that said voltage increases up to a maximum value when the load impedance decreases from its unloaded value, and is at a low value when said load impedance is in the vicinity of its unloaded value.

Abstract: The driving skill of a vehicle operator is determined according to how a driving operation is executed by the vehicle operator. The driving skill can be estimated by comparing an actual trajectory of a vehicle with a ideal or reference vehicle trajectory. The estimated driving skill is used as a control parameter of a vehicle steering system which, for instance, provides a steering property depending on the yaw rate of the vehicle, or provides a reaction opposing a steering input according to the yaw rate of the vehicle. Thus, a skilled vehicle operator will benefit from brisk handling of the vehicle, and can maneuver the vehicle at will, while an unskilled vehicle operator will benefit from stable handling of the vehicle, and will find the vehicle easier to handle and less tiring.

Abstract: The invention relates to a steering angle adjusting device with an operating element for adjusting the steering angle as a function of a corresponding operating element actuating parameter. According to the invention, steering angle adjustment takes place as a function of the operating element actuating parameter with a sensitivity that decreases with decreasing coefficient of friction and/or the maximum adjustable value of the operating element actuating value decreases with a decreasing coefficient of friction and/or an increasing lengthwise speed of the vehicle.

Abstract: A hydrostatic power steering system comprising a fluid motor (19) which receives pressurized fluid from a controller (17) in response to the rotation of a vehicle steering wheel (W). As the motor (19) or the steered wheels reach the stops, control logic (31) receives signals (37,77) representing steered wheel and steering wheel position, respectively, and generates appropriate command signals (33,27) to a pressure reducing/relieving valve (15) and to a proportional electromagnetic valve (23), respectively, closing the valve (15) somewhat, and opening the valve (23). A pressure differential is built between an additional fluid path (21) and the high pressure conduit (15c) between the controller (17) and the fluid motor (19). Pressure is communicated through the valve (23) into the conduit (51c), and back into the fluid meter (43) of the controller, preventing any further rotation thereof in response to an attempt to turn the steering wheel, thus eliminating travel limit slip.

Abstract: An apparatus for controlling a motion of a vehicle supported on steered and non-steered road wheels. A target vehicle motion value is calculated based on the steering angle and vehicle speed to provide a predetermined response characteristic related to a vehicle plane behavior. A target steering angle value for the non-steered road wheel to realize the vehicle plane behavior is calculated according to the target vehicle motion value. The non-steered road wheels are steered according to the calculated target steering angle value. The damping characteristic of the response characteristic is decreased as the vehicle speed increases.

Abstract: The invention relates to a hydraulic power steering system for motor vehicles, in the case of which the manual steering wheel is normally connected only by way of a control system with respect to the drive with a servomotor operating the steered vehicle wheels. In the event of a malfunctioning of the control system, a hydraulic forced coupling is automatically established between the servomotor and a hydraulic delivery unit which is constantly forcibly coupled with the steering handle, in order to form a "hydraulic linkage".

Abstract: A power steering device has a hydraulic actuator that generates steering assistance power by using hydraulic fluid fed from a pump driven by a brushless electric motor. The device controls the motor's rotation speed to have a preset steering assistance speed in a steering assistance mode, and a preset standby speed in a steering assistance release mode. The motor rotation speed is set to the steering assistance speed after being set to a maximum speed that exceeds the steering assistance speed in the steering assistance mode.

Abstract: A vehicle steering system has an electronic control system for coupling a steering device and the steered wheels of the vehicle, with the steering angle setpoint signal passing though a filter before a setpoint/actual value comparison is made. The filter passes essentially only those frequencies below an adjustable transition frequency. A switch is made to a low transition frequency when there is to be a direct translation between the steering device and the steered wheels of the vehicle.

Abstract: Timer action is done from the time point t.sub.1, where the detected vehicle speed determined by the vehicle speed signal S.sub.2 is 0, until the time point t.sub.6, where the detected vehicle speed exceeds 0, thereby determining the timer time T. The value of the axle load signal S.sub.1 is transiently held, beginning at the time point t.sub.2 where the period of time X has passed since t.sub.1. When the timer time T is longer than the set timer time T.sub.0, the value of the axle load signal S.sub.1 at the time point t.sub.5, the point chronologically backward by the period of time Y from t.sub.6, is read. Based on this read value, the opening of the control valve is adjusted to vary the assist force. Thus, even when a vibration occurs in the vehicle body during driving, the assist force by the power steering system is made constant, whereby a feeling during steering can be improved.

Abstract: A power steering apparatus has a flow amount detecting sensor for detecting an actuating oil flow amount on the exit side of an actuator operated by an actuating oil pressure generated by a hydraulic pump, and a control circuit for controlling the rotation of the motor for driving the hydraulic pump. The power steering apparatus has a flow amount variation detecting sensor for detecting a variation amount of an actuating oil flow amount on the exit side of the actuator and a control circuit for controlling the motor rotation on the basis of the variation amount. This is to compensate for the decrease in the flow of oil to the actuator caused by an expansion of a hose between the pump and the actuator.

Abstract: A device for the parameter-dependent control of a reaction force at an operating element, in particular a steering wheel of a motor vehicle, of a hydraulic power steering system. In this case, a parameter-dependent additional force is generated by an electric motor in addition to a hydraulically generated servo positioning force.

Abstract: A motor vehicle power steering gear has a proportional control valve with a cylindrical valve member riding rotatably on a spool shaft and connected thereto through a torsion bar. Electromagnetic apparatus for varying the magnitude of the effective restoring torque of the torsion bar comprises a stationary exciting coil, an inner pole member comprising an extension of the cylindrical valve member having a plurality of outwardly facing teeth and an outer pole member fixed on the spool shaft for rotation therewith and having an equal plurality of opposing inwardly facing teeth, the teeth defining an air gap axially beside the coil.

Abstract: An electric power steering apparatus comprises broken point characteristics determining means for determining a value of a steering torque signal corresponding to a broken point of a broken line function on the basis of a vehicle speed signal from a vehicle speed sensor, a broken line function circuit for determining the broken line function in accordance with the broken point determining signal determined by the broken point characteristics determining means and outputting an analog signal corresponding to the broken line function, and means for determining a target value of a motor current to drive an electric motor for assisting steering on the basis of the analog signal.

Abstract: To support the driver of a road vehicle, a yaw velocity r (in radian/s) around a vertical axis is measured, a driving speed v.sub.x (in m/s) is determined, an acceleration a.sub.x (in m/s.sup.2) in the driving direction is measured, a lateral acceleration is measured at two randomly selected locations at a distance of l.sub.a as a.sub.y1 (in m/s.sup.2, front) and a.sub.y2 (m/s.sup.2, rear), a steering wheel angle .delta..sub.H is measured at the vehicle steering column with a potentiometer, a vehicle wheel angle .delta..sub.L =.delta..sub.H /i.sub.L commanded by the driver is computed, a variable angle .beta..sub.F at the front axis is computed, and these measured parameters are used to calculate, in a microprocessor, according to the equations (4, 20 and 21), an additional steering angle .delta..sub.C, whose addition to the vehicle wheel angle .delta..sub.L commanded by the driver results in the overall wheel angle .delta..sub.F =.delta..sub.L +.delta..sub.C.

Abstract: A variable assist power steering system (10) uses both vehicle speed and steering valve inlet pressure to vary the steering assist provided. A system controller (30) receives speed and pressure data from sensors (24, 26) and produces a control signal for an actuator (28) that shunts fluid flow from the pump (22) to the steering valve (20) thereby affecting steering valve pressure which controls the rack piston (16) which changes the angle of the front vehicle wheels used for steering. The controller (30) employs a calibration table (32) with entries representing actuator current, vehicle speed and inlet pressure wherein the speed and pressure fall into ranges defined by equally spaced speed points and equally or unequally spaced pressure points. Having pressure points spaced with a distance between any two sequential points a power of two in sensor counts allows manageable bilinear interpolation of current versus speed and pressure without complicated divide operators.