Tokico, Ltd.

Tetsuo Katoh

Takao Nakadate

Hiroshi Murata

Hiromi Machida

Yasuo Inose

A cylinder apparatus including a piston slidably fitted in a cylinder having a hydraulic fluid sealed therein. A piston rod is connected at one end thereof to the piston. The other end portion of the piston rod extends as far as the outside of the cylinder through a seal block fitted to an open end portion of the cylinder. The seal block retains a double seal including a rod seal that is in sliding contact with the piston rod and an O-ring that resiliently biases the rod seal toward the piston rod. The seal block is provided with a projection extending between the O-ring and the rod seal to bear a part of biasing force applied to the rod seal from the O-ring. The projection is provided at a side of the O-ring and rod seal which is remote from the piston.

Cylinder apparatus

In a damping force control type hydraulic shock absorber according to the invention, an extension-side bypass passage extends through an extension-side chamber (17b) in a shutter (17). A check valve (28) allows the flow of hydraulic fluid only during the extension stroke. A contraction-side bypass passage extends through a contraction-side chamber (17a) in the same shutter (17). Disk valves (30) allow the flow of hydraulic fluid only during the contraction stroke. By rotating the shutter (17), alignment between an extension-side inlet port (31) and an extension-side inlet opening (34) changes and alignment between a contraction-side inlet port (32) and a contraction-side inlet opening (33) also changes, thereby controlling the passage area of each of the extension- and contraction-side bypass passages, and thus enabling different damping force characteristics to be simultaneously selected for the extension and contraction sides. Since the extension- and contraction-side chambers (17a, 17b) are independent of each other, no turbulent flow will occur in the shutter (17) when the direction of stroke of a piston rod (8) changes, and hence no noise will be generated.

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Kanagawa, Japan

Tetsuo Katoh