Shock absorber

Patent metadata

Field	Value
Publication number	US-10012282-B2
Application number	US-201514661576-A
Country	US
Kind code	B2
Filing date	Mar 18, 2015
Priority date	Mar 31, 2014
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A flow of hydraulic oil induced by sliding movement of a piston in a cylinder is controlled by a damping force generating mechanism to generate a damping force. A flow of hydraulic oil from a casing of the damping force generating mechanism toward a reservoir is regulated by a passage groove formed on the bottom of the casing so as to be directed downward in the reservoir. Thus, the hydraulic oil is efficiently supplied to a base valve from the damping force generating mechanism even when the hydraulic oil is sucked from the reservoir into a cylinder lower chamber through a passage in the base valve during the extension stroke of a piston rod. Therefore, it is possible to suppress a sharp reduction in pressure in the lower part of the reservoir and hence possible to suppress the occurrence of aeration and to obtain stable damping force characteristics.

First claim

What is claimed is:

1. A shock absorber comprising:
a cylinder having a hydraulic fluid sealed therein;
a piston disposed in the cylinder;
a piston rod connected to the piston and extended to an outside of the cylinder;
an outer tube provided around an outer periphery of the cylinder;
a reservoir formed between the cylinder and the outer tube and having the hydraulic fluid and a gas sealed therein;
a separator tube provided between the cylinder and the outer tube to form a passage between the separator tube and the cylinder, the passage communicating with an interior of the cylinder;
a separator tube opening formed in a side wall of the separator tube;
an opening provided in a side wall of the outer tube to face the separator tube opening;
a casing secured to the side wall of the outer tube such that an interior of the casing communicates with the reservoir through the opening of the outer tube; and
a damping force generating mechanism housed in the casing and connected to the separator tube opening to generate a damping force by controlling a flow of the hydraulic fluid, wherein:
a bottom of the casing has an opening that is connected to the opening of the outer tube;
at least one passage groove is formed on an inner side of the bottom of the casing, the at least one passage groove extending from the vicinity of an inner peripheral surface at an upper side of the casing to the opening; and
a flow of hydraulic fluid flowing from the interior of the casing toward the reservoir is rectified along the passage groove from the upper side of the casing toward the opening, and directed downward in the axial direction of the reservoir to flow into the reservoir,
wherein the at least one passage groove is formed in a V-shape such that the passage groove is forked at an upper end thereof and tapers toward a lower end thereof at which the passage groove communicates with the opening.

2. The shock absorber of claim 1 , wherein the passage groove is formed integrally with the bottom of the casing.

3. The reservoir of claim 2 , wherein the flow of the hydraulic fluid along the passage groove restricts the hydraulic fluid from flowing upward in the axial direction of the reservoir.

4. The shock absorber of claim 2 , wherein the casing is formed of a cylindrical body and the bottom is formed on one end side of the cylindrical body, and the bottom and the cylindrical body are formed of the same element.

5. The shock absorber of claim 2 , wherein the casing is formed of a cylindrical body and a bottom plate which is a discrete member that is separate from the cylindrical body; and
the bottom plate is secured in abutment with an inward flange portion formed in the cylindrical body.

6. The reservoir of claim 1 , wherein the flow of the hydraulic fluid along the passage groove restricts the hydraulic fluid from flowing upward in the axial direction of the reservoir.

7. The shock absorber of claim 1 , wherein the at least one passage groove has, in addition to the V-shaped passage groove, another passage groove formed in an inverted V-shape such that the passage groove is forked at a lower end thereof and tapers toward an upper end thereof at which the passage groove communicates with the opening.

8. The shock absorber of claim 1 , wherein the casing is formed of a cylindrical body and the bottom formed on one end side of the cylindrical body, the bottom being made of the same material as the cylindrical body.

9. The shock absorber of claim 1 , wherein the casing is formed of a cylindrical body and a bottom plate which is a discrete member that is separate from the cylindrical body; and
the bottom plate is secured in abutment with an inward flange portion formed in the cylindrical body.

10. The shock absorber of claim 1 , wherein the casing is formed of a cylindrical body and a bottom plate which is a discrete member that is separate from the cylindrical body;
the bottom plate is secured in abutment with an inward flange portion formed in the cylindrical body; and
the V-shaped passage groove is formed in the bottom plate.

11. The shock absorber of claim 1 , wherein the casing is provided with a passage member connecting the separator tube opening and the damping force generating mechanism; and
a chamber in the casing and the reservoir communicate with each other through a gap, the gap being defined between the passage member and the opening of the outer tube and between the passage member and the opening.

12. The shock absorber of claim 11 , wherein the passage member comprises a flange portion secured by being clamped between the bottom of the casing and the damping force generating mechanism; and
the passage groove extends radially outward of the casing beyond the flange portion to provide communication between the chamber in the casing and the opening.

13. A shock absorber comprising:
a cylinder having a hydraulic fluid sealed therein;
a piston disposed in the cylinder;
a piston rod connected to the piston and extending outside of the cylinder;
an outer tube provided around an outer periphery of the cylinder;
a reservoir formed between the cylinder and the outer tube and having the hydraulic fluid and a gas sealed therein;
a separator tube provided between the cylinder and the outer tube to form a passage between the separator tube and the cylinder, the passage communicating with an interior of the cylinder;
a separator tube opening formed in a side wall of the separator tube;
an opening provided in a side wall of the outer tube to face the separator tube opening;
a casing secured to the side wall of the outer tube such that an interior of the casing communicates with the reservoir through the opening of the outer tube; and
a damping force generating mechanism housed in the casing and connected to the separator tube opening to generate a damping force by controlling a flow of the hydraulic fluid, wherein:
the casing has a passage member connecting the separator tube opening and the damping force generating mechanism;
a first flow path communicating between a chamber in the casing and the reservoir is formed between the passage member and the opening of the outer tube;
the passage member of the casing is secured to be offset upward relative to the opening of the outer tube; and
a lower flow path area of the first flow path formed between the opening of the outer tube and a lower side of the passage member is larger than an upper flow path area of the first flow path formed between the opening of the outer tube and an upper side of the passage member.

14. The shock absorber of claim 13 , wherein:
the passage member has a flange portion secured by being clamped between the bottom of the casing and the damping force generating mechanism;
equally spaced radial grooves are formed in the bottom of the casing; and
the grooves form a second flow path between the grooves and the flange portion to provide communication between the chamber in the casing and the reservoir through the first flow path.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Kimura Yusei
• Katayama Yohei
• Harada Naofumi
• Shimazaki Satoshi

Classifications

• F16F9/48

  Arrangements for providing different damping effects at different parts of the stroke ({F16F9/346, F16F9/516} , F16F9/53 take precedence) · CPC title

• F16F9/46

  allowing control from a distance {, i.e. location of means for control input being remote from site of valves, e.g. on damper external wall (attachment of valve units to cylinders F16F9/325)} · CPC title

• F16F9/34 Primary

  Special valve constructions ({F16F9/44, F16F9/50 take precedence; filtering details F16F9/3285} ; valves in general F16K); Shape or construction of throttling passages · CPC title

• F16F9/3257 Primary

  in twin-tube type devices · CPC title

• F16F9/32

  Details · CPC title