Shock absorber and vehicle using the same

Patent metadata

Field	Value
Publication number	US-10012283-B2
Application number	US-201414776015-A
Country	US
Kind code	B2
Filing date	Mar 27, 2014
Priority date	Mar 28, 2013
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A minimum length-side property in which an extension-side damping coefficient signifies a hard state in a range (Aa 0 ) where the piston rod enters further inside the cylinder than a minimum length-side predetermined position (Sa 1 ), and a maximum length-side property in which the extension-side damping coefficient signifies a soft state in a range (Aa 4 ) where the piston rod extends further outside the cylinder than a maximum length-side predetermined position (Sa 4 ) are included. An extension-side damping force property between the minimum length-side predetermined position (Sa 1 ) and the maximum length-side predetermined position (Sa 4 ) includes a part (Sa 1 to Sa 2 , Sa 3 to Sa 4 ) in which a damping coefficient change rate with respect to a stroke of the piston rod is large and a part (Sa 2 to Sa 3 ) in which the damping coefficient change rate is small. At least when the piston rod strokes to the extension side from the minimum length-side predetermined position (Sa 1 ), the damping coefficient change rate is allowed to be large.

First claim

The invention claimed is:

1. A shock absorber comprising:
a cylinder in which a working fluid is sealed;
a piston slidably fitted into the cylinder and configured to divide the inside of the cylinder into two chambers including a first chamber which is an upper side of the cylinder and a second chamber which is a lower side of the cylinder;
a piston rod connected to the piston and extending toward an outside of the cylinder;
a communication passage configured to cause the two chambers to communicate and configured to allow the working fluid to flow between the two chambers according to movement of the piston; and
a damping force generating device installed at the communication passage and configured to limit a flow of the working fluid generated by movement of the piston to generate a damping force,
wherein the damping force generating device includes:
an extension-side damping valve configured to generate a damping force mainly in an extension stroke,
a compression-side damping valve configured to generate a damping force mainly in a compression stroke,
an extension-side pilot chamber provided on the extension-side damping valve, the extension-side pilot chamber configured to apply an internal pressure to the extension-side damping valve in a direction closing the extension-side damping valve,
a mechanism configured to cause the extension-side pilot chamber to communicate with the first chamber in a range where the piston rod enters further inside the cylinder than a minimum length-side predetermined position, the mechanism further configured to cause a first passage area communicating between the extension-side pilot chamber and the second chamber to be smaller than a second passage area communicating between the extension-side pilot chamber and the first chamber,

wherein, when the piston rod strokes to an extension side and when the piston rod is at an intermediate predetermined position, the first passage area communicating between the extension-side pilot chamber and the second chamber is configured to have a first passage area varying rate with respect to the stroke of the piston rod and a second passage area varying rate with respect to the stroke of the piston rod that is smaller than the first passage area varying rate, and
wherein, at least when the piston rod strokes to the extension side from the minimum length-side predetermined position, the first passage area is predetermined to have the first passage area varying rate.

2. The shock absorber according to claim 1 , wherein
a range of the stroke of the piston rod in which the first passage area has the second passage area varying rate is wider than a range of the stroke of the piston rod in which the first passage area has the first passage area varying rate.

3. The shock absorber according to claim 2 , wherein
a damping coefficient when the first passage area has the second passage area varying rate is determined such that a proportion of the damping coefficient to a critical damping coefficient becomes constant with respect to a change in mass added to the piston rod or the cylinder.

4. The shock absorber according to claim 2 , wherein
a damping coefficient when the first passage area has the second passage area varying rate is determined such that a proportion of the damping coefficient to a critical damping coefficient becomes constant with respect to a change in mass added to the piston rod or the cylinder.

5. The shock absorber according to claim 1 , wherein
a damping coefficient when the first passage area has the second passage area varying rate is determined such that a proportion of the damping coefficient to a critical damping coefficient becomes constant with respect to a change in mass added to the piston rod or the cylinder.

6. The shock absorber according to claim 1 , wherein
the damping force generating device further includes a mechanism configured to cause the extension-side pilot chamber to communicate with the second chamber in a range where the piston rod extends to the outside of the cylinder at a maximum length-side predetermined position, the mechanism configured to further cause the second passage area between the extension-side pilot chamber and the first chamber to be larger than the first passage area between the extension-side pilot chamber and the second chamber.

7. The shock absorber according to claim 6 , wherein
a range of the stroke of the piston rod in which the first passage area has the second passage area varying rate is wider than a range of the stroke of the piston rod in which the first passage area has the first passage area varying rate.

8. The shock absorber according to claim 6 , wherein
a damping coefficient when the first passage area has the second passage area varying rate is determined such that a proportion of the damping coefficient to a critical damping coefficient becomes constant with respect to a change in mass added to the piston rod or the cylinder.

9. The shock absorber according to claim 7 , wherein
a damping coefficient when the first passage area has the second passage area varying rate is determined such that a proportion of the damping coefficient to a critical damping coefficient becomes constant with respect to the change in mass added to the piston rod or the cylinder.

10. A vehicle comprising:
a vehicle body;
a plurality of wheels including a front wheel and a rear wheel; and
a shock absorber attached between only the rear wheel and the vehicle body,
the shock absorber including:
a cylinder in which a working fluid is sealed;
a piston slidably fitted into the cylinder and configured to divide the inside of the cylinder into two chambers including a first chamber which is an upper side of the cylinder and a second chamber which is a lower side of the cylinder;
a piston rod connected to the piston and extending toward an outside of the cylinder;
a communication passage configured to cause the two chambers to communicate and configured to allow the working fluid to flow between the two chambers according to movement of the piston; and
a damping force generating device installed at the communication passage and configured to limit a flow of the working fluid generated by movement of the piston to generate a damping force,

wherein the damping force generating device includes:
an extension-side damping valve configured to generate a damping force mainly in an extension stroke,
a compression-side damping valve configured to generate a damping force mainly in a compression stroke,
an extension-side pilot chamber provided on the extension-side damping valve, the extension-side pilot chamber configured to apply an internal pressure to the extension-side damping valve in a direction closing the extension-side damping valve,
a mechanism configured to cause the extension-side pilot chamber to communicate with the first chamber in a range where the piston rod enters further inside the cylinder than a minimum length-side predetermined position, the mechanism further configured to cause a first passage area communicating between the extension-side pilot chamber and the second chamber to be smaller than a second passage area communicating between the extension-side pilot chamber and the first chamber,

wherein, when the piston rod strokes to an extension side and when the piston rod is at an intermediate predetermined position, the first passage area communicating between the extension-side pilot chamber and the second chamber is configured to have a first passage area varying rate with respect to the stroke of the piston rod and a second passage area varying rate with respect to the stroke of the piston rod that is smaller than the first passage area varying

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Yamashita Mikio
• Takiguchi Kunio

Classifications

• F16F9/342

  Throttling passages operating with metering pins {(F16F9/486 takes precedence)} · CPC title

• B60G2202/24

  Fluid damper · CPC title

• B60G2500/10

  Damping action or damper · CPC title

• F16F9/48 Primary

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

• B60G13/08 Primary

  hydraulic · CPC title