Hitachi Automotive Systems, Ltd.

Hitachi Astemo Ltd.

Osamu Yuno

Shunsuke Mori

Takao Nakadate

Kosuke Kadokura

Yu Ishimaru

Hiroshi Murakami

Takashi Nezu

Yohei Katayama

Yasuhiro Aoki

Umi Tanabe

Shigeo Katayama

Tomoyuki Ri

Motohiro Hirao

Tomohiko Fujioka

Provided is a shock absorber in which a check valve seated on a seat portion (second seat portion) having an annular shape is quickly opened during a reverse stroke. As a result, a working fluid in a chamber on a downstream side can be quickly introduced into a back-pressure chamber. Hence, a delay in response of a damping force, which may be caused by sticking of the check valve to a relief valve, can be suppressed.

Shock absorber

The present invention provides a shock absorber capable of improving responsiveness during an extension stroke without leading to an increase in an axial length. A shock absorber includes a chamber provided on a one-side end of a pilot valve and disposed in communication with a cylinder upper chamber, a communication passage configured to establish communication between the chamber and a cylinder lower chamber via a compression-side passage, and a check valve configured to permit hydraulic fluid in the communication passage to flow into the cylinder lower chamber during an extension stroke.

Provided is a shock absorber that is so designed that fail-down is prevented, which is caused when solenoid thrust is relatively small. The shock absorber comprises a chamber disposed on one side of a valve element and communicating with a cylinder's one side chamber and a cylinder's other side chamber, a first communication passage allowing the chamber and the cylinder's one side chamber to communicate with each other, and a second communication passage allowing the chamber and the cylinder's other side chamber to communicate with each other. The first communication passage includes a first orifice, and the second communication passage includes a second orifice.

In a shock absorber, an extension-side check valve permitting a flow of hydraulic fluid directed from a common passage to a compression-side passage side, and a compression-side orifice establishing communication between the compression-side passage and a compression-side back-pressure chamber are provided in an extension-side discharge passage. A compression-side check valve permitting a flow of hydraulic fluid directed from the common passage to an extension-side passage side, and an extension-side orifice establishing communication between the extension-side passage and an extension-side back-pressure chamber are provided in a compression-side discharge passage. A pilot valve includes a valve body slidably inserted in the common passage, and a valve spring biasing the valve body in a valve-opening direction. The valve body includes a fitting portion fitted in a passage between the back-pressure chamber on an upstream side and the common passage on a downstream side when the valve body is stroked in the valve-opening direction.

A damping force control type shock absorber capable of achieving both air bleeding performance and damping force responsiveness at reduced cost. When a pilot valve () is closed during the extension stroke of a piston rod (), a cylinder upper chamber (A) is communicated with a back-pressure chamber () through a passage () including an orifice (), a communicating passage (), a pilot chamber (), and a communicating passage (). At this time, the cylinder upper chamber (A) is not communicated with a cylinder lower chamber (B); therefore, damping force responsiveness is ensured. Further, because there is no need to provide a check valve in the passage, it is possible to suppress an increase in manufacturing cost. Further, air entering the pilot chamber () moves upward through the communicating passage (). Therefore, the air can be discharged into the cylinder upper chamber (A) through the passage ().

Damping force control type shock absorber

An intermediate cylinder is disposed between an outer cylinder and an inner cylinder. The intermediate cylinder forms a passage between the inner cylinder and itself, through which a hydraulic fluid as an electrorheological fluid flows. The intermediate cylinder is supplied (applied) with a voltage through an electrode connector. The intermediate cylinder includes a ring member. The ring member is provided with an extending portion which extends toward the outer cylinder. The extending portion of the ring member is inserted with an electrode pin as an imparting unit for imparting a voltage to the intermediate cylinder.

Cylinder device

A shock absorber in which a flow of hydraulic oil caused by sliding movement of a piston in a cylinder is controlled by a pilot type main valve and a pilot valve to generate damping force. The valve-opening operation of the main valve is controlled by adjusting the pressure in a pilot chamber with the pilot valve. A valve block and a solenoid block are connected together into one unit and inserted into a casing before being secured with a nut. At this time, an actuating rod of the solenoid block is engaged with a pilot valve member retained by a pilot spring and a fail-safe spring in a cylindrical portion of a pilot body of the valve block.

Growing community of inventors

Yokohama, Japan

Osamu Yuno