Hitachi Automotive Systems, Ltd.

Hitachi Astemo Ltd.

Fumiyuki Yamaoka

Mikio Yamashita

Masaru Kouyama

Atsushi Maeda

Shunsuke Mori

Makoto Nishimura

Takao Nakadate

Yohei Katayama

Kunio Takiguchi

Kenji Noda

Daiki Miyazawa

Yusuke Maegawa

Atsufumi Ishimoto

Kengo Hase

Joji Endo

A shock absorber includes: a cylinder; a piston slidably inserted into the cylinder; a piston rod connected to the piston and extending outside the cylinder; a main valve that generates a damping force; a pilot chamber that applies pressure to the main valve; an introduction passage that introduces the fluid into the pilot chamber; a pilot passage that communicates the pilot chamber and a downstream side of the main valve with each other; and a control valve provided in the pilot passage. In an upstream side of the pilot passage from the control valve, the pilot passage is provided with a first orifice, a first passage provided in parallel with the first orifice, a first check valve that is opened at a predetermined differential pressure and allows a flow toward the control valve through the first passage, and a second orifice.

Shock absorber

Hydraulic fluid in a cylinder's lower chamber is introduced into a back pressure chamber through the outer periphery of an extension-side main valve during a compression stroke of a piston rod. This eliminates the necessity of forming paths by arranging a plurality of discs and a check valve, the paths for introducing into the back pressure chamber the hydraulic fluid in the cylinder's lower chamber that becomes an upstream chamber during the compression stroke. This makes it possible to decrease the axial length of a shaft portion of the piston rod and therefore the entire length of a cylinder, and also downsize a shock absorber.

Provided is a shock absorber capable of smoothly changing a damping force in a low speed range of piston speed and of opening a main valve with a smaller differential pressure. An auxiliary valve () is provided on an upstream side of a main valve () in series with the main valve (). Thus, the damping force in the low speed range of the piston speed can be smoothly changed. Further, the main valve () has a simply-supported structure in which an inner peripheral side thereof is prevented from being clamped and is supported in a cantilever state. Thus, the main valve () can be opened with a smaller differential pressure.

Provided are a damper configured such that the axial play between a coil case and a case member can be eliminated without increasing a size of a solenoid, and a method of assembling the damper. An O-ring (seal member) is elastically supported by a tapered hole formed in an inner peripheral surface of a case member and a tapered shaft formed in an outer peripheral surface of a coil case, and a retaining ring is configured to receive an axial force generated by the O-ring. The configuration enables the play between the coil case and the case member of the solenoid to be eliminated. A damping force regulation mechanism, and in turn the damper, may be made more compact in comparison with a case in which the O-ring is received by the opening side end face of the case member.

Damper and method of assembling damper

A suspension system, which is used together with a vehicle including a vehicle body, a front wheel, and a rear wheel, includes a mechanical damping force variable shock absorber disposed between the vehicle body and the front wheel and configured to mechanically change a damping force, and a damping force adjustable shock absorber disposed between the vehicle body and the rear wheel and configured to adjust a damping force by an actuator.

Shock absorber-equipped vehicle

PROBLEM Provided is a damping force control type shock absorber capable of obtaining an appropriate damping force even in the event of a failure independently of the stoke of a valving element of a solenoid valve. MEANS FOR SOLVING A pistonhaving a piston rodconnected thereto is fitted in a cylinderhaving hydraulic oil sealed therein, and a flow of hydraulic oil induced by movement of the pistonis controlled by a damping force generating mechanismto generate a damping force. In the damping force generating mechanism, damping force is generated by a pilot-type main valveand a normally-open pilot valvewhich is a solenoid valve, and the damping force is adjusted by energization of a coil. A fail-safe valveis provided downstream of the pilot valve. During normal operations, the fail-safe valveopens the flow path through excitation of the coilof the pilot valve. In the event of a failure, due to loss of excitation, the fail-safe valverestricts the flow path to generate an appropriate damping force in place of the pilot valve, which has become inoperable.

Damping force control type shock absorber

This suspension device is provided with a shock absorber () that is capable of altering damping force using the position of a piston rod () such that at least any one of the following characteristics are achieved, namely, first characteristics in which, within a range where the piston rod () is extending out from a cylinder () beyond a first predetermined position, the extension-side damping force is in a soft state and the compression-side damping force is in a hard state, and second characteristics in which, within a range where the piston rod () is retracted inside the cylinder () beyond a second predetermined position, the extension-side damping force is in a hard state and the compression-side damping force is in a soft state; and an operating force adjustment mechanism that is capable of adjusting at least one of the operating force in the roll direction of a vehicle, and the operating force in a pitch direction of the vehicle.

Suspension device

A shock absorber has an inclined surface that is inclined to a moving direction of the free piston in at least one of a free piston contact surface of a free piston with which an elastic body is in contact and a housing contact surface of a housing with which the elastic body is in contact. A shortest distance between the free piston contact surface and the housing contact surface is changed by movement of the free piston.

A joined body includes a first member having a female portion, and a second member having a male portion inserted in the female portion at one end, and an annular groove along an outer circumference of the male portion. The first member and the second member are fitted to each other. A plurality of joint portions is formed on a side wall of the female portion. The joint portions are joined to the male portion by being pushed in the annular groove. A pressing portion is formed at the female portion so as to face a position of the male portion axially different from the annular groove of the male portion. The pressing portion pressed against the male portion.

Joined body, shock absorber, and method for manufacturing shock absorber

A shock absorber includes a first passage () or () and a second passage (), () or () in communication with each other and configured to allow a working fluid to flow between two chambers () and () based on movement of a piston (), and a passage area adjustment mechanism () or () configured to adjust a passage area of the second passage () or () depending on a position of a piston rod () is installed to have at least one of a maximum length-side property in which an extension-side damping force becomes soft and a compression-side damping force becomes hard in a range in which the piston rod () extends to an outside of a cylinder () farther than a maximum length-side predetermined position, and a minimum length-side property in which the extension-side damping force becomes hard and the compression-side damping force becomes soft in a range in which the piston rod () enters an inside of the cylinder () further than a minimum length side predetermined position.

Oil grooves of a shutter and oil holes of a stepped rod constitute first orifices as variable orifices whose opening areas are variable according to the rotational position of the shutter. The oil grooves of the shutter and oil holes of the stepped rod constitute third orifices as variable orifices. Cut portions of inner disk valves constitute second orifices. The opening areas of the variable orifices are changed by rotating the shutter, thereby controlling damping force characteristics in a low piston speed region and the relief pressures of pressure control valves independently of each other, and thus increasing the degree of freedom for adjusting the damping force characteristics.

A shock absorber has an inclined surface that is inclined to a moving direction of the free piston in at least one of a free piston contact surface of a free surface with which an elastic body is in contact and a housing contact surface of a housing with which the elastic body is in contact. A shortest distance between the free piston contact surface and the housing contact surface is changed by movement of the free piston.

A shock absorber includes first passages configured to communicate two chambers to flow a working fluid therebetween by movement of a piston, and a second passage configured to communicate with one chamber of the two chambers. The first passages have damping valves configured to suppress a flow of the working fluid generated by movement of the piston to generate a damping force. The second passage has a variable orifice having an area adjusted by an elastic member when a piston rod moves in an extension direction, a pressure chamber installed in series with the variable orifice, and a free piston configured to vary a volume of the pressure chamber by movement of the piston.

A frequency-dependent mechanism provided at the lower end of a piston rod includes a tubular housing displaceable in an inner tube, together with the piston rod as one unit, and further includes a free piston and O-rings. A shutter of a passage area varying mechanism is provided with an axially extending inner hole, orifices, and oil grooves. The opening area between oil holesC and the orificesB is changed according to the rotational position of the shutter. The opening area between oil holesD andE and the oil groovesC andD and the opening area between oil holesF andG and the oil groovesE andF are also variably adjusted according to the rotational position of the shutter.

A shock absorber includes a first passage and a second passage to which a working fluid flows out from one chamber in a cylinder by movement of a piston, a damping valve installed on the first passage and configured to regulate a flow of the working fluid caused by sliding of the piston to generate a damping force, a back pressure chamber applying an internal pressure to the damping valve in a closing direction of the damping valve, a back pressure chamber inflow oil passage introducing the working fluid from one chamber into the back pressure chamber, a pressure chamber provided in-between on the second passage, and a free piston installed in the pressure chamber so as to freely slide in the pressure chamber.

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Sagamihara, Japan

Fumiyuki Yamaoka