Abstract: A power steering system for a motor vehicle comprising a hydraulic reaction device (11) by which reaction power is generated on the steering column of the vehicle, depending on the speed thereof. According to the invention, a accumulator (14) is provided on the line (13) connecting the reaction device (11). Said accumulator serves as a low-pass filter and decouples the reaction device from oscillations in pressure due to uneven road surfaces.

Abstract: A steering system (1) for a vehicle with a first steering arrangement (6), with a first sensor (7), with a second steering arrangement (8), which includes an articulated steering, which has a second sensor (9), and with a steering unit (5). To improve the steering comfort, the steering unit (5) is fixedly connected with the first steering arrangement (6) and the second steering arrangement (8) is connected with a follow-up arrangement, which comprises the first sensor (7), a control device (10) and a valve arrangement (11).

Abstract: A detector for detecting the steering angle of a steering mechanism of a motor vehicle includes: a steering angle detecting section that receives data from a steering angle sensor and detects a relative steering angle indicative of a direction and degree of a steering operation; a steering angle midpoint computing section that repeatedly performs a computation when the motor vehicle is traveling to determine a steering angle midpoint value; an absolute steering angle calculating section that calculates an absolute steering angle on the basis of the steering angle midpoint value and the relative steering angle; and a rewritable nonvolatile memory for storing the latest steering angle midpoint value. Immediately after turn-on of the ignition key, before the steering angle midpoint is newly determined, the steering angle midpoint value stored in the nonvolatile memory is used as a tentative steering angle midpoint value for the calculation of the absolute steering angle.

Abstract: A rack and pinion power steering system 10 is provided and includes a variable orifice valve 22 which controls the flow of fluid in and out of a hydraulic cylinder 20. Variable orifice valve 22 is communicatively coupled to a source of pressurized fluid 30 by use of a conduit 42 and an electronically controlled valve assembly 38. The pressurized fluid received through conduit 42 controls the operation of valve 22. Based upon the pressure of the received fluid, valve 22 selectively increases and decreases the volume of fluid flow in and out of cylinder 20, thereby causing cylinder 20 to have enhanced damping characteristics during certain vehicle operating conditions (e.g., during relatively high vehicle speed operating conditions).

Abstract: An electric powered hydraulic steering system (10) for a vehicle comprises a power steering motor (12) having a housing (18) with an exterior surface (16) and an interior chamber (24). The power steering motor (12) further includes a rack bar (26) for turning the steerable wheels of the vehicle. The rack bar (26) extends through the interior chamber (24) of the housing (18). A piston (34) is attached to the rack bar (26) and divides the interior chamber (24) into two chamber portions (38 and 40) for receiving a fluid. The piston (34) moves the rack bar (26) linearly within the interior chamber (24) depending upon a pressure differential between the two chamber portions (38 and 40).

Abstract: A vehicle power steering system for providing steering assistance to a vehicle operator to control rotation of a vehicle's road wheels is disclosed. The system includes a steering wheel, a torque converter, an annular magnet, a transducer, a motor, and a controller. The steering wheel has an input shaft for receiving and transmitting a rotational force from the vehicle operator. The torque converter includes a translator and a torsion bar, the torsion bar is connected to the input shaft and twists in response to the rotational force applied to the steering wheel, the translator is coupled to the torsion bar and moves axially in response to twisting of the torsion bar. The annular magnet is fixedly secured to the translator and generates a magnetic field. The transducer is located proximate to the magnet for generating an output signal indicative of a change in the magnet field.

Abstract: A hydraulic steering system, which is used, in particular, for a mobile working machine, and has a steering unit that can be actuated by a first steering member, which is constructed as a steering wheel, that has a first fluid connection, which is connected to a pressure chamber of a steering motor, the pressure chamber being subjected to pressure for a steering movement to the left, and that has a second fluid connection, which is connected to a pressure chamber of the steering motor, the pressure chamber being subjected to pressure for a steering movement to the right, and which has a control valve that can be actuated by a second steering member, which is constructed in the manner of a joystick, and likewise has fluid connections that are connected to the pressure chambers of the steering motor.

Abstract: A hydraulic steering arrangement with a steering handwheel, which is connected with a hydraulic steering unit, and a steering motor, which is connected with a pump via a steering valve. In a steering arrangement of this kind an improvement of the steering comfort is desired. For this purpose, a supply line is located between the steering unit and the pump, and a pressure reduction valve is located in the supply line.

Abstract: A hydraulic power steering apparatus 1 which is arranged so that a damper valve 10 is disposed in hydraulic oil circuits 8 and 9 for connecting an oil passage selector valve 11 in a gear box with right and left oil chambers of a power cylinder 6. The damper valve 10 comprises a spool valve. And a control oil chamber 21 of the spool valve 10 is connected with a hydraulic oil feed passage 18 for connecting a hydraulic pump 13 which is driven by an internal combustion engine so as to discharge hydraulic oil, with the oil passage selector valve 11. Its back pressure chamber 17 is connected with a hydraulic oil circulating passage 19 for connecting the oil passage selector valve 11 with a reservoir tank 12. Orifices 27 and 28 are provided in connecting oil passages 22 and 20, such that when discharge oil pressure of the hydraulic pump 13 rises, opening of the spool valve 10 increase.

Abstract: A device for controlling the steering angle of a vehicle over a wide range maintaining improved control precision. The device controls the steering angle &thgr;d through a steering drive device 10 so as to come in agreement with a target angle &thgr;0. A steering angle detection device includes a first potentiometer 11 that produces a first angle detection value &thgr;1 and a second potentiometer 12 that produces a second angle detection value &thgr;2. A target torque operation means 20 includes an angle operation unit 22 for operating the steering angle based on the first and second angle detection values, and the angle operation unit 22 produces the first angle detection value as the steering angle outside the second angular range, and produces the second angle detection value as the steering angle inside the second angular range.

Abstract: An electric power steering apparatus comprises a housing 22b for housing rotatably a steering shaft 18 interlocked with a steering wheel (not shown), an electric motor 8a which has a through hole 50 through which a screw member 53 is to be inserted and is attached to the housing 22b by the screw member 53 through the through hole 50, and a gear mechanism 57, 57a, connected to the electric motor 8a through a joint 55, for transmitting a torque of the electric motor 8a to the steering shaft 18. The joint 55 is formed by a synthetic resin so as to detach the electric motor 8a from the housing 22b by an impact force in an axial direction of the steering shaft 18. Even when a portion of a vehicle body and a mounting bracket, etc. belonging to the vehicle body are caught on the electric motor during the primary collision or secondary collision, it is possible to sufficiently absorb the impact force of the secondary collision.

Abstract: The invention concerns a hydraulic dual circuit steering system with

Abstract: The object of the present invention is to provide a method for limiting the hydraulic maximum pressure of a power-assisted steering system, which permits effective pressure limitation and thus protects the individual elements of the power-assisted steering system, i.e., a pressure limitation not far above the desired maximum operating pressure, but on the other hand does not require an overdimensioning of the individual segments of the power-assisted steering system.

Abstract: A power steering apparatus, including a pump, a power cylinder, a control valve and a switching valve. The switching valve is for connecting the cylinder chambers in accordance with pressure change of the operating fluid responsive to operation of the control valve in order to return the steering wheel toward a neutral position. When the rotation of the steering wheel is substantially stopped, the switching valve reacts to the pressure change in order to connect the cylinder chambers, so as that the higher hydraulic pressure of one of the cylinder chamber releases to the other. This hydraulic pressure releasing of the operating fluid returns the power piston toward the neural position, smoothly. The steering wheel also returns toward the neutral position in accordance with the return of the cylinder piston, so as that restoring force of the steering wheel is enhanced.

Abstract: A supplemental steering system is provided for a machine having first and second brakes actuable for slowing rotation of first and second drive outputs or wheels, a brake actuator, and a main or primary steering system. The brake actuator is connected with a first port and a second port of a supplemental steering control valve having a first chamber and a second chamber. The first port communicates with the first chamber and the second port communicates with the second chamber. The supplemental steering control valve further includes a piston located in the bore connected to a steering input and having a neutral position generally equidistant between the first and second chambers. First and second brake ports respectively communicate the first and second chambers with the first brake.

Abstract: A hydraulic steering device, in particular for vehicles, is disclosed, having a housing in which two sliders are arranged to move relative to one another and together form at least one adjustable throttle, a restoring device for restoring the two sliders to their neutral position being provided, one of the two sliders being driveable and the other of the two sliders being in operative connection with a measuring device. In such a steering device it is desirable to improve the correlation between steering torque and flow amplification; in particular it is desirable to linearize the relationship better. For that purpose the measuring device is arranged in a flow path closed in itself, and operates as a pump, while an open flow path runs past the closed flow path from an inlet connection arrangement to an outlet connection arrangement.

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: A hydraulic steering device is disclosed, having a housing in which an inner control slider and an outer control slider are arranged so that they are rotatable relative to one another and which together are arranged as alterable flow path means between a supply connection arrangement and a working connection arrangement. In such a steering device it is desirable to produce a remote control facility of simple construction. To that end, each control slider is connected to a driving slider, and between the two driving sliders there is created at least one pressure chamber which is acted upon by fluid under pressure, and a change in volume of the pressure chamber effects a relative displacement of the two control sliders.

Abstract: A damper valve arrangement is combined with a servomotor of a hydraulic power steering system to form a steering damper. Certain valve elements are adjusted by bimetallic components in order to compensate for temperature-dependent changes in the viscosity of the hydraulic medium.

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 self-aligning steering system for a vehicle having a steering wheel and a plurality of front wheels. The invention has a hydraulic fluid circulation means responsive to the steering wheel and a left and a right hydraulic cylinder for maneuvering the front wheels in response to the hydraulic fluid circulation system. The hydraulic cylinders have an internal fluid release system such that the volume of hydraulic fluid in the left and the right hydraulic cylinders is equalized through the hydraulic fluid circulation means. Equal hydraulic fluid volume ensures that the front wheels are in alignment.

Abstract: An adjustable power steering valve for a vehicle steering system for selectively varying the pump pressure to the steering box. The power steering valve is positioned between the pressure line from the pump to the steering box and the return line from the steering box to the reservoir. It functions, when closed, to apply fall pump pressure to the steering box. The power steering valve can be opened to a predetermined adjustable position to bypass fluid from the pressure line to the return line to selectively reduce the fluid pressure applied to the steering box.

Abstract: A power assisted steering apparatus for a vehicle has a driving source and an actuator for the vehicle's steering mechanism, to power assist the steering operation. The driving source, such as an engine, continuously drives a pump. A working passage is arranged so that working oil discharged from the pump is introduced into the actuator. A check valve is disposed in the working passage, between the actuator and the pump so that the working oil flows only one way to the actuator. An accumulator is connected to the working passage, between the check valve and the actuator to maintain a predetermined pressure in the working passage. A regulator is connected to the working passage, between the pump and the check valve to regulate flow to the actuator. When the pressure within the working passage reaches the predetermined pressure, the working fluid is dumped to a reservoir, bypassing the check valve, the accumulator, and the actuator.

Abstract: A power steering device capable of improving both operability of a vehicle and a feeling of the steering. The power steering device includes an association mechanism for mechanically associating a handle with wheels, a power cylinder for generating assisting force, and a control valve connected to the power cylinder and adapted to be changed over depending on torque inputted thereto from the handle and kept at a neutral position unless the torque is inputted thereto. The control valve functions to control the amount of fluid fed to the power cylinder when it is changed over and close a cylinder port connected to the power cylinder when it is at the neutral position.

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 includes a hydraulic pump for discharging working fluid, an actuator for producing a steering assisting force by means of working fluid, a hydraulic passage for connecting the hydraulic pump and the actuator, a check valve arranged to the hydraulic passage to allow flow of working fluid from the hydraulic pump to the actuator and preventing flow thereof in the opposite direction, an accumulator connected to the hydraulic passage downstream of the check valve, a pressure switch for detecting a pressure within the hydraulic passage downstream of the check valve, a control unit for controlling the hydraulic pump in response to the pressure switch, and a display for showing an anomaly of the power steering device. When determining the anomaly of the power steering device, the control unit stops the hydraulic pump and/or makes the display show the anomaly.

Abstract: A hydraulic power steering system for a vehicle comprising a hydraulic fluid displacement pump, operated by a thermal engine of the vehicle and provided with a suction port and a delivery port, a reservoir for collecting said fluid, connected to suction port, a double-acting hydraulic cylinder, capable of controlling direction of front wheels of the vehicle, and a distribution unit fitted with an inlet port, connected to delivery port, a vent port, connected to reservoir and two service ports, connected to respective chambers of hydraulic cylinder; distribution unit comprising a first and a second distributor, respectively controlled by hydraulic cylinder and by a steering wheel of the vehicle and movable with respect to each other; pump being of the variable displacement type and system further comprising a flow request sensor from and to chambers of cylinder and a device for adjusting displacement of pump, controlled by sensor.

Abstract: The correction system of this invention simulates a power steering leak which the driver can manually adjust or automatically tune to offset vehicle drift and/or pull generated by road crown, wind, vehicle alignment, and tires during straight ahead driving. The drift and pull correction system taps into the bypass line of a vehicle's power steering system and can be added to the vehicle as an aftermarket device. For example, the standard rack or power gear, the power steering pump and reservoir and the steering assembly of the power steering system can be used in combination with the addition of correction lines and correction valves of the steering correction system to correct the vehicle's steering system for "straight ahead driving" without operator assistance. The magnitude of the drift and/or pull is a direct function of the magnitude of the leak and the back (parasitic) pressure in the system.

Abstract: A jerk control valve adapted for use in a pilot operated steering system has a pilot operated valve biased to an open position by a spring for communicating left steer and right steer pilot lines to a tank through a pair of orifices. The pilot operated valve is moveable to a closed position blocking communication through the first and second orifices when the highest pressure of the left and right steer pilot lines exceeds a predetermined value. The left and right steer pilot lines are continuously communicated with the tank through a pair of orifice devices.

Abstract: A hydraulic control system for work vehicles including a control unit to control the steering wheels of a vehicle via a cylinder and a priority valve which by a first load-sensing system controls the pressure fluid flow to the control unit and to a subsequent proportional valve group. By a second load-sensing system the proportional valve group controls the pressure fluid flow to secondary hydraulic motors or work cylinders to control the work tools of the vehicle. The control system also includes an open-centre valve connection and a fixed displacement pump. The first load-sensing system is connected with a second load-sensing system, whereby drop-off of the pressure fluid flow to the control unit is avoided at simultaneous operation of the latter and of one or several of the proportional valves as is the case with known control systems. Hereby a control system is provided which is particularly agreeable to operate for the driver of the work vehicle.

Abstract: The invention changes over to another steering ratio automatically and very safely on the transition from servo to emergency operation. In the steering system, only a few of the lines (13) link the metering pump (10) to one of the cylinder connections (7, 8) and in each of the other lines (13') there is a changeover unit (16) which also links the lines (13) to the cylinder connections (7, 8) or the delivery connection (6) depending on the method of operation. These steering systems are used in mobile systems, especially slow-moving vehicles.

Abstract: In a power steering apparatus comprising a pump, a reservior, a power cylinder having two opposite chambers, and a rotary control vale, the rotary control valve consists of a first control portion which communicates between the pump and the reservior, and a second control portion which communicates not only between the pump and the reservior but also with the power cylinder. In the first control portion, each of four underlapping variable orifices is so provided as to take the form of underlap in itself. In the second control portion, two underlapping variable orifices are provided on the side of the pump, and besides each of two overlapping variable orifices is so provided as to take the form of overlap in itself on the side of the reservior. In this manner, while a steering wheel is operated within a predetermined angle, an opening area of the overlapping variable orifice changes little.

Abstract: A hydraulic power steering gear assembly includes an assembly body defining a piston chamber having opposed chamber ends with plunger passages formed in the ends, a reciprocating piston and a chamber having opposed ends and a passage extending between the piston ends, a check valve at each end of the piston passage, and a plunger assembly in each plunger passage with each assembly including a spring frictionally holding assembly in the passage and a poppet extending into the chamber to unseat a ball valve as the piston is moved toward one end of the chamber.

Abstract: A hydraulic steering apparatus comprises a throttle (10) with a bypass line, eliminating the function of the throttle (10) in the direction of the steering cylinder (2). The throttle (10) is disposed between the control valve (3) of the steering apparatus (1) and the cylinder volume of the steering cylinder (2) on the piston rod side. The throttle (10) is used in connection with hydraulic steering apparatus for slow-moving vehicles.

Abstract: An automatic rear wheel self-centering device for four-wheel steering vehicles automatically performs the rear wheel self-centering operation when the steering mode of the vehicle returns from another steering mode to the standard steering mode. The device has a branch conduit branched from a conduit leading from the steering unit to the steering mode selection valve. A conduit control valve is mounted to the branch conduit and is changeable between a neutral position blocking the branch conduit, a first position connecting the branch conduit to one side chamber of the rear wheel steering cylinder and a second position connecting the branch conduit to the other side chamber of the cylinder. The spool of the conduit control valve moves synchronous with a linear movement of the piston of the rear wheel steering cylinder, thereby changing the position of the conduit control valve between the above three positions.

Abstract: A power-assisted steering system for a vehicle comprising a hydraulic motor (1) for providing vehicle steering assistance, an open center servo-valve (6) for supplying the hydraulic motor (1) with hydraulic fluid, a hydraulic pump (7) for supplying hydraulic fluid to the servo-valve (6) and to the hydraulic motor (1), and an electric motor (13) for driving the hydraulic pump (7). The hydraulic pump (7) is controlled by controlling electrical power consumed by the electric motor (13). At least one sensor (15) repetitively monitors at least one operating parameter of the power-assisted steering system. At least one microprocessor (17) repetitively calculates reference values that vary as a function of a monitored level of the at least one operating parameter.

Abstract: A vehicle speed responsive power steering apparatus enables a pressure which acts upon a power cylinder to be variably controlled in accordance with a vehicle speed or the like, thus allowing an assisting force to be controlled in a variable manner. A control valve CV selectively connects a pump P and a tank T to left and right chambers CL, CR of a power cylinder. The control valve comprises a first and a second fluid pressure bridge circuit 10, 20. The first fluid pressure bridge circuit includes a left and a right path 12, 13, in which a first and a second pair of variable throttles 1R, 1L and 2L, 2R are disposed which are opened or closed in response to a steering operation. The left and the right chamber of the cylinder are connected to the respective paths at the junctions between the variable throttles.

Abstract: In a power steering apparatus is disclosed, in which a current control outputs a voltage to be applied to an electric motor so as to set a current flowing in an electric motor to a predetermined current value by feedback of a motor current detected by a motor current detection circuit, while a motor application voltage indicator indicates a voltage to be applied to the electric motor. And a motor application voltage selector selects the lower of the voltage outputted by the current control and the voltage indicated by the motor application voltage indicator as the voltage to be applied to the electric motor and supplies the selected voltage to a motor drive circuit for driving the electric motor. Hence the apparatus needs no motor drive element of large capacity, thereby enabling to minify and reduce production cost.

Abstract: A fluid supply system provides hydraulic fluid to a series combination of an automotive fan motor and a power steering unit. There is a bypass line around the fan motor for prioritizing the operation of the power steering unit. A normally closed pressure sequencing valve opens the bypass line when the pressure across the overall series combination exceeds a predetermined limit. Optional second and third bypass lines are disclosed for respectively bypassing either the power steering unit or the fan motor in case of abnormal conditions therein.

Abstract: A hydraulic power steering apparatus includes a motor-driven pump which discharges pressurized working fluid at a flow rate proportional to the rotational speed. A load-pressure responsive valve is connected to a discharge passage to which the pressurized fluid is discharged from the pump. The load-pressure responsive valve bypasses the pressurized fluid to a reservoir when the control valve is in a neutral state, thereby reducing the amount of the pressurized fluid supplied to the control valve, and increases the amount of the pressurized fluid supplied to the control valve when the load pressure of the pump increases upon operation of the control valve. With this control, the energy consumed by the pump can be reduced.

Abstract: A servo-assisted rack-and-pinion steering system includes a rack which cooperates with a pinion which is capable of limited movement transversely or, in particular, parallel to the longitudinal axis of the rack. The movements actuate the servomotor or its control elements.

Abstract: A main servo valve 4 is switched in response to a relative angular displacement between an input and an output shaft for supplying an operating oil discharged from a pump to or displacing such operating oil from a power cylinder 6. An auxiliary servo valve 10 is disposed between the input and the output shaft and is connected in parallel relationship with the main servo valve 4 so as to be operated jointly therewith. A vehicle speed responsive valve 16 which opens or closes a flow path in accordance with the vehicle speed is disposed upstream of the auxiliary servo valve 10. The pump comprises a pair of pumps 2, 12 of smaller size. At low speeds, the speed responsive valve 16 is closed, and the oil discharged from the pair of pumps 2, 12 are merged to be introduced into the main servo valve 4. As the vehicle speed increases, the speed responsive valve 16 is gradually opened, and at a vehicle speed above a given value, one of the pumps, 12, ceases to operate.

Abstract: Known all wheel steer arrangements use standard spool-type valves which are inherently subject to leakage that results in the front and rear wheels getting out of synchronization due to the leakage. In the subject invention, a hydraulic system has front and rear pairs of steerable wheels respectively interconnected by front and rear fluid actuated mechanisms. A steering valve delivers pressurized fluid to the front fluid actuated mechanism for steering of only the front pair of wheels and to both the front and rear fluid actuated mechanisms to steer the front and rear pairs of wheels simultaneously but in opposite directions. Furthermore, a rear steer valve mechanism is provided to independently direct pressurized fluid to the rear fluid actuated mechanism to steer the rear pair of wheels independent of the front pair of wheels.

Abstract: Unbalanced oscillatory pressures, developed on the power piston of hydraulic servoactuator systems cause vibrations on actuator housing supports. An unbalanced oscillatory force results, when two sides of the power piston are subjected to two unequal oscillatory forces induced by a disturbance. The two important disturbances are: pump flow rate oscillations, caused by power source torque oscillations; and, load oscillations. The invention is a hydraulic actuator connected in parallel to the power piston and designed to cancel vibrations by eliminating the unbalanced oscillatory pressure on the power piston. This is accomplished by designing the piston frequency of the invention, defined as tuning frequency, to be equal to the unbalanced oscillatory pressure frequency.

Abstract: A power assisted steering system, in particular, for motor vehicles, contains a servomotor (2), a servopump (3), a tank (4), a control valve (1) with a controllable feedback device (5), and a control member (46) whose choke cross section can be altered as a function of the vehicle speed. Control valve (1) is made as a four-way valve and has a supply connection (22, 23), a feedback connection (7), and two working connections (8, 10) for the lines (11, 12) that lead to the two working chambers of servomotor (2). Between feedback device (5) and supply connection (22, 23), there is arranged a device (13) for piling up the pressure medium stream and the device is made according to one practical example as a choke (50, 51). With the help of this choke (50, 51), one can achieve a hydraulic centering component in addition to a mechanical centering component.