Shock absorber

Patent metadata

Field	Value
Publication number	US-9309948-B2
Application number	US-201414221600-A
Country	US
Kind code	B2
Filing date	Mar 21, 2014
Priority date	Mar 29, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A shock absorber including a damping force generation mechanism ( 30 a ) includes a spring member ( 106 a ) having radially extending spring portions ( 117 ) having high spring constants and circumferentially extending spring portions ( 118 ) having low spring constants. The radially extending spring portions and the circumferentially extending spring portions are integrally configured so that biasing forces thereof act dynamically linearly. An annular stepped portion limits strokes of the circumferentially extending spring portions and is provided on a cylindrical wall portion of a pilot body. As a result, within a range of damping force control, only the radially extending spring portions of the spring member are elastically deformed, whereby the durability of the spring member is enhanced, and only biasing forces of the radially extending spring portions of the spring member act on a pilot valve member, and thereby variation in a damping force is reduced so that the performance is improved.

First claim

What is claimed is:

1. A shock absorber comprising:
a cylinder sealingly containing hydraulic fluid;
a piston slidably and fittedly inserted in the cylinder;
a piston rod coupled to the piston, and extending out of the cylinder; and
a damping force generation mechanism configured to generate a damping force by controlling a flow of the hydraulic fluid generated by a sliding movement of the piston,
wherein the damping force generation mechanism includes a main valve configured to generate the damping force, a back pressure chamber configured to apply a back pressure in a direction for closing the main valve, an introduction passage configured to guide the back pressure into the back pressure chamber, a discharge passage configured to discharge the back pressure in the back pressure chamber, and a control valve disposed in the discharge passage,
wherein the control valve includes a valve body disposed in the discharge passage, a valve seat, an actuator configured to generate a force for moving the valve body toward the valve seat according to a current, and a spring unit configured to bias the valve body in a direction opposite from a direction in which the valve body is moved by the actuator,
wherein the spring unit includes one member configured to act on the valve body throughout a whole range of the movement of the valve body, and a limiting member configured to limit a deflection of a part of the spring member by abutting a predetermined portion of the spring member against the limiting member with a predetermined deflection of the spring member when the valve body is moved toward the valve seat, and
wherein the spring member has a spring constant acting on the valve body due to a deflection of another part of the spring member at which a deflection is not limited, after limitation of the deflection of the spring member by the limiting member, which is higher than that of the spring member before limiting the deflection of the spring member.

2. The shock absorber according to claim 1 , wherein the spring member is made of an annular plate-like spring, and
wherein the limiting member includes an abutment portion disposed on a valve seat side and configured to abut against between an outer circumference and an inner circumference of the plate-like spring when the plate-like spring is deflected by a predetermined amount.

3. The shock absorber according to claim 2 , wherein the spring member is disposed in such a manner that the valve body is attached to an inner circumferential side thereof, and an outer circumferential side thereof is held by the valve seat side.

4. The shock absorber according to claim 3 , wherein a lower spring constant is set to the outer circumferential side of the spring member relative to a portion of the spring member configured to abut against the abutment portion than a spring constant of an inner side of the spring member.

5. The shock absorber according to claim 4 , wherein the spring member includes an outer annular portion configured to be held by the valve seat side and an inner annular portion where the valve body is disposed, and
wherein a circumferentially extending spring portion and a radially extending spring portion are provided between the outer annular portion and the inner annular portion, the circumferentially extending spring portion having one end connected to the outer annular portion, and extending circumferentially, the radially extending spring portion having one end connected to the circumferentially extending spring portion and an opposite end connected to the inner annular portion, and extending radially.

6. The shock absorber according to claim 5 , wherein the spring member includes a connecting portion connecting the circumferentially extending spring portion and a radially extending spring portion, the connecting portion abutting the limiting member to be limited by the limiting member.

7. The shock absorber according to claim 1 , wherein the limiting member is configured to gradually limit the deflection before the plate-like spring is deflected by the predetermined amount.

8. The shock absorber according to claim 1 , wherein the range of the movement of the spring member from a position where the deflection of the part of the spring member is limited by the limiting member to a position where the valve body is seated on the seat portion is a range used in damping force control.

9. The shock absorber according to claim 1 , wherein the actuator is configured to generate a force for moving the valve body toward the valve seat, and the spring member biases the valve body in a direction in which the valve body is separated from the valve seat.

10. The shock absorber according to claim 1 , wherein the damping force generation mechanism includes a fail-safe valve, the fail-safe valve being configured to be closed by the valve body being retracted with the biasing force of the spring member, when the actuator does not generate the force.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Katayama Yohei
• Ohara Hiroki
• Matsumura Sadatomo

Classifications

• F16F9/3257

  in twin-tube type devices · CPC title

• F16F9/3485 Primary

  characterised by features of supporting elements intended to guide or limit the movement of the annular discs (F16F9/3488 takes precedence) · CPC title

• F16F9/341

  comprising noise-reducing or like features, e.g. screens (F16F9/3415 takes precedence) · CPC title