Koyo Seiko Company, Ltd.

Other

Manabu Takaoka

Kazumasa Tabata

Tatsuhiro Yamamoto

Hiroshi Kawaguchi

Shiro Nakano

Terukazu Nakajima

Hideki Higashira

Masayuki Watanabe

Hiroshi Ooishi

A motor operated power steering device which transmits rotational force from a steering assistance motor to a steering shaft by way of a gear fitted around the outer circumference of the steering shaft. A torque limiter fitted in between the steering shaft and the gear comprises a torque setting member, which is subject to diametric deformation as a result of being fitted in between the outer circumference of the steering shaft and the inner circumference of the gear. Diametric force is applied to the steering shaft and the gear in accordance with the diametric deformation of the torque setting member. The limit torque value of the torque limiter corresponds to the diametric deformation of the torque setting member.

Motor operated power steering device

A steering apparatus for automobiles having steering operating means which is not mechanically connected to a steering mechanism, a pair of steering motors provided to different positions in the steering mechanism, and a steering control unit for distributing a necessary steering force which is obtained on the basis of a deviation between an operating position of the steering operating means and an actual operating position of the steering mechanism in a prescribed ratio so as to determine target values of the outputs of the steering motors.

Steering apparatus for automobile

In an electric power steering device, a rotating member is screwed onto a rack, which meshes with a pinion rotated by steering manipulation, via a screw mechanism. The rotation of a motor for generating steering assistance force is transmitted to the rotating member via a gear mechanism. The vehicle is turned by longitudinal movement of the rack caused by rotation of the pinion. The steering assistance force is applied in the longitudinal direction of the rack by driving the rotating member by means of the motor. The gear ratio of the gear mechanism is set such that the speed of rotation of the rotating member is equal to or greater than the speed of rotation of the motor.

Electric power steering device

A torque is transmitted from a steering assistance motor to a steering shaft via a gear. The first rotation restraining element, which is radially deformed by being sandwiched between the outer circumference of the steering shaft and the inner circumference of the gear, exerts a radial force corresponding to the radial deformation on the steering shaft and the gear, to generate a torque based on friction for restraining the relative rotation between the shaft and gear. The restraining torque generated based on the deformation of the first rotation restraining element is smaller than the breaking torque of the second rotation restraining element, which is fitted to the steering shaft and the gear via clearances so as to restrain the relative rotation between the shaft and gear.

In a motor operated power steering device, a drive shaft accommodation hole in a housing communicates with a opening for fitting a steering assistance power generation motor. In the accommodation hole, a drive shaft, which is driven by the motor, is supported by rolling bearings at two separate points along the axial direction. A steering shaft is linked to a driven gear which meshes with a driving gear provided around the outer circumference of the drive shaft. Around the outer circumference of the drive shaft, there is a ring shaped preload applying member, the outer circumference of which has a male threaded section. The preload applying member is screwed into a female threaded hole, which is concentric with the accommodation hole, in between the motor and the rolling bearing closest to the motor, so that it is able to apply preload along the axial direction to both rolling bearings.

A lock nut having a tapered portion at one end thereof is screwed halfway through an output shaft that transfers motion to a steering mechanism. A tapered fitting hole formed through an axis of a worm wheel is fitted onto an outer circumference of the tapered portion with a slip plate interposed therebetween. By tightening the lock nut, the worm wheel is pressed and fixed to a support portion formed on a portion of the output shaft, and a worm directly connected to an output side of a steering assisting electric motor is made to engage with a gear formed on the outer circumference of the worm wheel. In normal operation, the torque of the electric motor is transmitted to the worm wheel via the worm, and further on to the output shaft via friction on the slip plate. Upon application of an excessive rotational torque in the event of a motor lock, slippage occurs on the slip plate to allow free rotation of the output shaft.

Power steering apparatus

A hydraulic pressure control valve, wherein a valve body having six oil grooves on its outer periphery at specified intervals is rotatably disposed in a cylindrical casing having six oil grooves on its inner periphery at specified intervals, and throttles are constructed on both sides of the respective oil grooves, thereby two throttling units each of which consisting of six throttles, are constructed and respective two throttles facing to each other in the radial direction among respective six throttles constructing respective throttling units have regions in which throttle areas do not substantially change until the relative angular displacement between the valve body and the casing reaches a predetermined magnitude.

Hydraulic pressure control valve

A hydraulic pressure control valve of the present invention applied in hydraulic power steering includes a cylindrical casing whose plural first grooves disposed on its circumferential surface at stated intervals are brought in communication with different destinations of pressure oil, and a valve body which is inserted rotatably into the casing and whose second grooves of the same number as the first grooves, disposed on its peripheral surface at stated intervals are brought in communication alternately with a high pressure source and a low pressure source, and a portion thereof is disconnected with the low pressure source. At corners on the casing opposing each other across the communicating portions on both sides of the disconnected portion of the valve body, notches are formed in such a shape that, until the relative angular displacement between the valve body and casing reaches the predetermined magnitude, variations of communicating areas produced between the first and second grooves by the relative angular displacement is substantially not produced. In the hydraulic pressure control valve, the first groove of the valve body interposed between the notches is not in communication with the low pressure source, and the pressurized oil which flows in through one communicating portion of this portion is introduced into the groove of the adjacent casing through the other communicating portion without flowing back to the low pressure source, so that flowing noises of pressured oil produced when the relative displacement is produced between the valve body and casing can be reduced sharply.

Growing community of inventors

Kashiba, Japan

Manabu Takaoka