Hitachi Automotive Systems, Ltd.

Kenji Noda

Mikio Yamashita

Takao Nakadate

Fumiyuki Yamaoka

Yohei Katayama

Yoshiaki Totani

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.

Shock absorber

A piston coupled to a piston rod is inserted in a cylinder, and an outer cylinder is disposed around the cylinder so as to define a reservoir therebetween. A separator tube is disposed around the cylinder so as to define an annular passage therebetween. The piston rod can be locked and unlocked by closing and opening an electromagnetic open/close valve so as to block and allow a flow of hydraulic fluid through a flow passage between the annular passage and the reservoir. The separator tube has a greater thickness. O-rings are disposed so as to provide seals between the separator tube and the cylinder. The separator tube extends to positions such that the ends of the separator tube overlap a base valve and a rod guide, thereby holding the respective ends of the cylinder. Due to this configuration, it is possible to prevent deformation of the cylinder and the separator tube due to an increase in the hydraulic pressure.

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Yamato, Japan

Kenji Noda