Kyb Corporation

Kayaba Industry Company, Ltd.

Kayaba Kogyo Kabushiki Kaisha

Takashi Teraoka

Tatsuya Masamura

Kiyoshi Inoue

Keiji Saito

Kazuhisa Nakamura

Kazutaka Inamitsu

Takashi Itoh

Futoshi Yoshida

Eizou Urata

Shock absorber including a suction passage allowing flow only from a reservoir towards a pressure side chamber, a rectifying passage allowing flow only from the pressure side chamber towards an expansion side chamber, and a damping force variable valve allowing flow only from the expansion side chamber towards the reservoir. A large pressure-side pressure chamber communicating with the pressure side chamber, and an outer peripheral expansion-side pressure chamber communicating with the expansion side chamber sandwich a free piston slidably moving within a bottom housing forming a pressure chamber. Because a pressure-side pressure-receiving area of the free piston is larger than an expansion-side pressure-receiving area in a contraction operation in which a piston moves downward, the free piston can move downward even in a uniflow-type shock absorber in which pressure in the expansion side and pressure side chambers become equal whereby damping force can be reduced during an input of high-frequency vibration.

Shock absorber

A shock absorber includes a suction passage permitting flow only from a reservoir toward a compression-side chamber, a rectification passage permitting flow only from the compression-side chamber toward an extension-side chamber, and a variable valve permitting flow only from the extension-side chamber toward the reservoir. A large chamber as a compression-side pressure chamber communicating with the compression-side chamber and an outer periphery chamber as an extension-side pressure chamber communicating with the extension-side chamber are partitioned in the shock absorber by a free piston that moves slidably within a bottom member serving as a housing. A compression-side pressure-receiving area of the free piston is larger than an extension-side pressure-receiving area. Therefore, even in the uniflow shock absorber with the extension-side chamber and the compression-side chamber at equal pressures during the contraction operation, the damping force is reduced under conditions in which high frequency is input since the free piston moves downward.

A shock absorber includes; a free piston that partitions the compression chamber into an expansion-side compression chamber and a contraction-side compression chamber; an expansion-side flow passage that connects the expansion-side chamber with the expansion-side compression chamber; a contraction-side flow passage that connects the contraction-side chamber with the contraction-side compression chamber; an expansion-side bypass valve provided in the expansion-side flow passage to admit only a flow directed from the expansion-side chamber to the expansion-side compression chamber and generate resistance; a contraction-side bypass valve provided in parallel with the expansion-side bypass valve to admit only a flow directed from the expansion-side compression chamber to the expansion-side chamber and generate resistance; an expansion-side elastic stopper configured to stop the free piston at an expansion-side stroke end; and a contraction-side elastic stopper configured to stop the free piston at a contraction-side stroke end.

A piston of a magnetorheological fluid shock absorber is provided with a piston core having a small diameter portion mounted on an end portion of the piston rod, an enlarged diameter portion formed continuously in an axial direction with a diameter larger than the small diameter portion and forming a stepped portion, and a large diameter portion formed continuously in the axial direction with a diameter larger than the enlarged diameter portion and having a coil; a ring body surrounding the outer periphery of the piston core and forming a flow passage of the magnetorheological fluid between itself and the large diameter portion; a plate formed annularly and arranged on the outer periphery of the small diameter portion and mounted on one end of the ring body; and a stopper mounted on the small diameter portion and sandwiching the plate between the stopper and the stepped portion.

Magnetorheological fluid shock absorber

A shock absorber includes at least one of an expansion-side sensitive unit and a contraction-side sensitive unit. The expansion-side sensitive unit has an expansion-side actuating chamber that communicates with an expansion-side chamber and a contraction-side chamber, an expansion-side free piston that partitions the expansion-side actuating chamber into a first expansion-side pressure chamber and a second expansion-side pressure chamber, and an expansion-side spring element configured to bias the expansion-side free piston to compress the first expansion-side pressure chamber. The contraction-side sensitive unit has a contraction-side actuating chamber that communicates with a contraction-side chamber and a reservoir, a contraction-side free piston that partitions the contraction-side actuating chamber into a first contraction-side pressure chamber and a second contraction-side pressure chamber, and a contraction-side spring element configured to bias the contraction-side free piston to compress the first contraction-side pressure chamber.

A shock absorber includes a cylinder, a piston, a piston rod, a damping passage, a bypass path, a shutter, a biasing member, and a control spring secured to the cylinder by one end. Another end of the control spring is opposed to the shutter. When the piston exceeds a predetermined position with respect to the cylinder by displacing on the compression-side chamber side, the shutter is pushed by the control spring and closes the bypass path. The control spring is a conical coil spring. The other end side of the control spring has a small diameter. A guide ring, which is slidably in contact with an inner periphery of the cylinder, is mounted to the small-diameter side end of the control spring.

A damping device comprises a piston that partitions an interior of a cylinder into first and second working chambers. A flow-rate-dependent damping force generating element connects the first and second working chambers. A first pressure chamber and a second pressure chamber divided by a free piston are formed integrally with the piston. A first connecting passage connects the first working chamber and the first pressure chamber, and a second connecting passage connects the second working chamber and the second pressure chamber. By providing a relief valve that allows fluid to flow from the first working chamber into the second working chamber, an increase in the generated damping force during a high speed operation of the piston can be suppressed, regardless of a vibration frequency of the piston.

Damping device

A shock absorber includes a suction passage allowing flow only from a reservoir towards a pressure side chamber, a rectifying passage allowing flow only from the pressure side chamber towards an expansion side chamber, and a damping force variable valve allowing flow only from the expansion side chamber towards the reservoir. Large, and small and outer peripheral chambers in a bottom housing sandwich a free piston. The small chamber communicates the outer peripheral chamber with the expansion side chamber. The large chamber communicates with the pressure side chamber through first and second valves. During a contraction in which a piston moves downward, even in a uniflow-type shock absorber in which pressure in the expansion side chamber and the pressure side chamber become equal, the free piston can move downward due to a difference in pressure-receiving areas. Even if a stretching speed reaches a high range, the first and second valves are opened, and damping force is reduced.

A magnetorheological fluid shock absorber includes a piston slidably arranged in a cylinder in which magnetorheological fluid is sealed. The piston includes a piston core which is attached to an end part of a piston rod and on the outer periphery of which a coil is provided, a flux ring which surrounds the outer periphery of the piston core and forms a flow passage for the magnetorheological fluid between the piston core and the flux ring, a first plate which is arranged on the outer periphery of the piston rod and specifies the position of one end of the flux ring in an axial direction with respect to the piston core, a second plate which is arranged on the inner periphery of the other end of the flux ring, and a first snap ring which is fitted to the inner periphery of the flux ring and fixes the second plate.

A shock absorbing device includes a cylinder. A partition wall member is inserted into the cylinder to be free to slide and partitions an interior of the cylinder into two operating chambers. A passage connects the two operating chambers. A free piston is inserted into a pressure chamber to be free to slide and partitions the pressure chamber into one chamber that communicates with one operating chamber via a one side flow passage and another chamber that communicates with the other operating chamber via another side flow passage. A spring element generates a biasing force for suppressing displacement of the free piston relative to the pressure chamber. One or both of a bypass flow passage that connects the other chamber and the one operating chamber and a bypass flow passage that connects the one chamber and the other operating chamber is provided. A relief valve is provided in the bypass flow passage.

Shock absorbing device

A shock absorber interposed in parallel with a suspension spring between a vehicle wheel and a vehicle body of a vehicle comprises a main piston () partitioning a cylinder () into a first operating chamber (R) and a second operating chamber (R), and connected to a piston rod (). The first operating chamber (R) and the second operating chamber (R) are connected by a laminated leaf valve (V, V) under a first flow resistance. A passage () connects one of the pressure chambers (RA, RB) partitioned by a free piston () and the first operating chamber (R) under a second flow resistance. A passage () connects the other of the pressure chambers (RA, RB) and the second operating chamber (R) under a third flow resistance. The shock absorber displays stable damping force characteristics as a result of a spring (S) supporting the free piston () in a predetermined neutral position.

Sufficient pressure is produced in a pocket of a hydrostatic bearing when a corresponding cylinder is about to switch from a suction stroke to a discharge stroke in order to prevent solid contact of sliding faces. A plurality of cylinders are arranged on a circle around a center axis of a cylinder block rotatably supported in a housing. Pistons reciprocates in the respective cylinders. A suction port and a discharge port provided to the housing selectively communicate with the respective cylinders in accordance with a rotational position of the cylinder block. A drive shaft inclined relative to the center axis of the cylinder block, a rotation transmitting mechanism for transmitting rotation of the drive shaft to the cylinder block for rotating the cylinder block synchronously with the drive shaft, and a rotating disk rotating together with the drive shaft and cooperatively engaged with the pistons are further provided. A fixed sliding contact face is formed in the housing to have a sliding contact with a rear face of the rotating disk. Pressure pockets are formed on the rear face of the rotating disk in correspondence with positions of the respective pistons. Pressure paths for conducting hydraulic pressure in the respective cylinders to the respective pressure pockets via the pistons are further provided. There is further provided a pressure introducing mechanism for introducing a high pressure fluid to a pocket moving along the fixed sliding contact face along with the rotating disk at a position in which a corresponding cylinder is about to switch from a suction stroke to a discharge stroke.

Hydraulic pump

A hydraulic pump or motor comprises a rotating disk member (31) supported free to rotate in a housing (11), and a cylinder block (14) supported free to rotate in the space of the housing (11) around a rotation axis inclined to the rotation axis of the rotating disk member (31). The rotating disk member (31) and cylinder block (14) are connected by a joint (17), and they are rotated in the same way by a drive shaft (12). A hemispherical shoe (29) in contact with the rotating disk member (31) via a spherical surface and having a smooth surface (29A) on the other side, comes in contact with a pad (27) of synthetic resin attached to the tip of a piston (20). The pad (27) has a smooth support surface (27A) perpendicular to the piston axis, and comes in contact with the smooth surface (29A) of the shoe (29) on this support surface (27A). A pocket (27D) for leading a cylinder internal pressure through the piston is formed on the contact surface between the pad (27) and shoe (29) forming a hydrostatic bearing. Each of the pistons (20) is pushed in the extending direction by a spring (21). A cylindrical piston cap (23) formed of a low friction synthetic resin on the outer circumference of the piston (20) slides in a cylinder bore (18).

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Gifu, Japan

Takashi Teraoka