Jidosha Kiki Co., Ltd.

Hitachi, Ltd.

Tadaaki Fujii

Naosuke Masuda

Toshiro Yoda

Takeshi Ohe

Yoshio Suzuki

Hideo Konishi

Fumiyuki Yamaoka

Kohtaro Shiino

Ichiro Koike

Yoshio Tobisawa

Hiroto Iwata

Eiichi Tomioka

Yuuichi Kimura

Konomu Sanpei

An electric power steering system, includes a torque sensor disposed to a steering shaft to detect a steering torque. A first pinion is disposed to the steering shaft. A rack shaft is in mesh with the first pinion and connected with the steering shaft to change a rotational motion of the steering shaft to an axial motion of the rack shaft and provided to be operated in relation to the steering shaft. A first motor is connected with the first pinion to generate a steering assist torque in accordance with the steering torque detected by the torque sensor. A second pinion is disposed to be separate from the first pinion and in mesh with the rack shaft. A second motor is connected with the second pinion to generate a steering assist torque in accordance with the steering torque. A first control circuit is provided on a first control board for the first motor. A second control circuit is provided on the second control board for the second motor. The first control circuit monitors an abnormality in control state of the second control circuit and the second control circuit monitors an abnormality in control of the first control circuit.

Electric power steering system

An electric motor for driving an oil pressure pump which feeds pressurized oil to a power cylinder comprises a brushless d.c. motor. An onboard main battery comprises a main battery which is onboard an electrically driven vehicle and which is constructed as a high tension d.c. voltage source delivering a high voltage on the order of 96 to 600V. The battery is directly connected to the motor, and a controller is connected therebetween to provide a pulse width modulated variable voltage signal to the motor from the battery.

Power steering apparatus with pump driven by pulse width modulated

A electric motor, which drives a fluid pressure pump used to derive a steering assist force, is controlled in a required manner using a simplified arrangement. Specifically, a pump 11 which feeds a fluid pressure in order to produce an assist force is driven by a D.C. brushless motor 11 which is provided with means 18 for detecting a rotational position of a rotor 23 thereof. Motor control means 14, 15 drives and controls the motor to rotate at a given number of revolutions. Vehicle speed detecting means 16 detects a running speed of a vehicle. The motor control means controls the number of revolutions of the brushless motor on the basis of information representing a vehicle speed, a number of revolutions of the rotor which is determined by utilizing a signal from the rotor position detecting means, and information from means which detect a steer angle and a steering angular rate.

Power steering apparatus with motor driven pump

A variable capacity or displacement type pump by which a pump discharge quantity is variably controlled in accordance with the revolution number, which has simple construction to contributes easier machining and assembling, and is reliable in operation. A cam ring is movably arranged to define a pump chamber around a rotatable rotor within a pump body and is biased so that the volume of the pump chamber is made maximum. Sealing members are provided in an annular space between the cam ring and the pump body so as to define first and second hydraulic pressure chambers through which the cam ring is driven to move. A switch valve is provided to control the hydraulic pressure transmitted to the first and second chambers in accordance with the quantity of the flow discharged from the pump chamber.

Variable displacement pump

A cam ring for forming a pump chamber on the outer periphery of a rotor which is rotatable in a body is arranged movably, and is urged in a direction in which the volume of the pump chamber is made maximum. Sealing means are interposed in an annular gap space on the outer periphery of the cam ring between the cam ring and the body, thereby forming first and second fluid-pressure chambers for allowing the cam ring to undergo displacement by moving. A spool-type changeover valve is provided which is operated in accordance with the discharge flow rate of the pressure fluid from the pump chamber to control the fluid pressure supplied to the first and second fluid-pressure chambers. The fluid pressure on the downstream side of a metering orifice 29 provided in a pump discharge-side passage 28 is introduced into the second fluid-pressure chamber for imparting moving displacement in the direction in which the volume of the pump chamber is made maximum, through a passage 37 via a second valve chamber 32b. It is possible to control the swinging of the cam ring, and to prevent fluctuations in the flow rate and a decline in the flow rate on the discharge side of the pump.

Variable displacement pump having a changeover value for a pressure

A cushioning material sheet to be interposed between a rack support and a press plug for applying an elastic force provided by a spring is formed such that at least its one end face is tapered. Slide-contact surfaces of the rack support and the press plug to be brought into contact with the two end faces of the cushioning material sheet are so formed as to move the cushioning material sheet in a direction perpendicular to a rack support direction, along which the thickness of the cushioning material sheet is decreased. A biasing member is provided to bias the cushioning material sheet in this direction of movement, thereby obtaining a proper meshed condition between a pinion and a rack.

Rack-and-pinion steering apparatus

An improvement to an electrically driven power steering apparatus which utilizes an electric motor is disclosed. A bevel gear of a greater diameter is mounted on a steering shaft so as to be axially displaceable thereon, and an urging mechanism is connected between the bevel gear and the steering shaft. The urging mechanism renders the bevel gear to be incapable of rotation relative to the steering shaft, and also urges the teeth thereof toward the teeth of a bevel gear of a reduced diameter which is coupled to the electric motor. This prevents a backlash from occurring between the both bevel gears, thus preventing the occurrence of sounds of percussion as the both gears abut against each other.

Electrically driven power steering apparatus

A steering apparatus for a vehicle steers both front and rear wheels and has an electric power steering unit for steering the rear wheels with a rotational force of a motor and a controller for generating a rear wheel steering signal in response to a vehicle speed and a front wheel steering angle. The controller includes a plurality of pattern memories for storing rear wheel steering angles, one of which is read out in response to a detected front wheel steering angle in accordance with ratios of rear wheel steering angles to front wheel steering angles. The ratios are predetermined or given as a function of vehicle speeds.

Steering apparatus for vehicle

A power steering apparatus includes a control valve of disc type which controls the delivery to or displacement from a power cylinder of a hydraulic fluid. A pair of mating parts are formed on the input and the output side for integral rotation therewith. A substantially C-shaped spring is engageable with the mating parts, which are maintained in position by the resilience of the spring.

Power steering apparatus

A power steering apparatus includes a pair of projections formed on the input and the output side, respectively, and also includes a substantially C-shaped spring disposed in surrounding relationship with the input shaft so that the both projections are maintained in their neutral position. In the neutral position, a circumferential clearance between the end faces of a notch formed in the spring and the projections is maintained substantially zero. The projection formed on the input side engages the lateral side of an inner race of a bearing which rotatably carries the input shaft, thereby preventing a withdrawal of the input shaft. Hydraulic fluid used in the control valve is utilized to define a hydraulic bearing between the input and the output shaft.

A power steering apparatus is provided including a control valve or rotary type which controls the supply to or discharge from a power cylinder of a hydraulic fluid. A valve rotor is integrally formed with a projection within the region of a valve sleeve, which is formed with an opening therein to permit the free end of the projection to extend therethrough to the exterior thereof, with the projection being disposed in the opening to leave a given spacing therebetween, as viewed in the direction of rotation of the valve sleeve. Another projection is integrally provided on the valve sleeve, and the both projections are maintained at given positions by the resilience of a spring which is disposed in surrounding relationship with the valve sleeve. As a result, the both projections are provided at axially close locations and in a region where an input and an output shaft abut against each other. This arrangement is preferred in consideration of the mechanical strength. Since the spring is disposed in surrounding relationship with the valve sleeve, the involved construction may be made compact while assuring a resilience of a sufficient magnitude. The C-shaped spring is configured in a manner such that stresses produced therein remain to be uniform throughout the entire body thereof. This allows the spring and hence its mounting structure to be reduced in size.

A plurality of pump sections are received in a stack in a body. Each of the pump sections include a cam ring disposed in surrounding relationship with a rotor having vanes thereon, and a pair of sideplates which closes the opposite sides of the cam ring. All of the pump sections are driven by a common drive shaft, thereby providing a compact pump unit having a reduced axial length. The outermost sideplates are subject to a discharge pressure from the respective pump sections to urge the various components of the individual pump sections to be held against the body. In this manner, the components are maintained at given accurate locations, eliminating the likelihood of a liquid leakage and simplifying the arrangement.

Pump unit

A standing wave ratio detecting apparatus is disclosed which comprises an integration circuit for integrating a traveling wave detection voltage V.sub.F, a comparator circuit for comparing the output voltage V'.sub.F of the integration circuit with a reflected wave detection voltage V.sub.R to a voltage E.sub.o proportional to the voltage ratio V.sub.R /V'.sub.F, a control circuit receiving the output voltage E.sub.o of the comparator circuit and turned on or off according as the output voltage E.sub.o is put in a high level or in a low level to lower or raise the output voltage V'.sub.F of the integration circuit, thereby conducting such a control as making the output voltage V'.sub.F approximately equal to said reflected wave detection voltage V.sub.R and maintaining the amplitude of the output voltage E.sub.o constant, a smoothing circuit for deriving an average voltage corresponding to the ratio V.sub.R /V.sub.F of the reflected wave detection voltage V.sub.R to the traveling wave detection voltage V.sub.F from the output voltage E.sub.o of the comparator circuit, and a meter for indicating the average voltage from the smoothing circuit.

Standing wave ratio detecting apparatus

A standing wave ratio detecting apparatus comprising a first comparator for comparing a traveling wave detection signal with a sawtooth or triangular wave signal having an amplitude proportional to the traveling wave detection signal to generate a first pulse signal, a generator receiving the first pulse signal to generate the sawtooth or triangular wave signal, a second comparator for comparing the sawtooth or triangular wave signal with a reflected wave detection signal to generate a second pulse signal having a duty cycle representative of the standing wave ratio and a meter device for averaging out the second pulse signal and indicating the averaged value. By this construction determination of the standing wave ratio is facilitated without troublesome operation.

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Saitama, Japan

Tadaaki Fujii