Shock absorber

Patent metadata

Field	Value
Publication number	US-12222018-B2
Application number	US-202017640857-A
Country	US
Kind code	B2
Filing date	Sep 25, 2020
Priority date	Oct 2, 2019
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

This shock absorber includes a piston main body and a piston band. The piston main body has, at an outer peripheral portion thereof, a stepped portion including a large-diameter surface portion, a stepped surface portion and a small-diameter surface portion. The piston band has, at an outer peripheral portion thereof, a large diameter portion, a medium diameter portion formed so as to have a smaller diameter than the large diameter portion, and a small diameter portion formed between the large diameter portion and the medium diameter portion so as to have a smaller diameter than the medium diameter portion, in a state before being disposed in a cylinder. At one end on the side close to a tip portion of a piston rod, an inner peripheral surface is inclined toward the piston main body side from the large-diameter surface portion to a small-diameter surface portion of the stepped portion.

First claim

The invention claimed is:

1. A shock absorber comprising:
a bottomed cylinder-shaped cylinder in which a working fluid is enclosed;
a piston rod having a base end portion that is inserted into the cylinder, and a tip portion that protrudes out of the cylinder;
a piston that is fixed to a base end portion side of the piston rod and defines an inside of the cylinder into a one-side chamber and an other-side chamber; and
a rod guide provided on a side opposite to a bottom portion of the cylinder to guide the piston rod,
wherein the piston includes:
a piston main body that is fixed to the piston rod; and
a piston band that is provided on an outer peripheral portion of the piston main body and is in sliding contact with an inner peripheral portion of the cylinder,
wherein the piston main body has a stepped portion including a large-diameter surface portion, a stepped surface portion, and a small-diameter surface portion, at one end on a side close to the tip portion of the piston rod, of the outer peripheral portion on which the piston band is mounted,
wherein the piston band has, at an outer peripheral portion thereof, a large diameter portion that is formed on the side close to the tip portion of the piston rod, a medium diameter portion that is formed on a side far from the tip portion so as to have a smaller diameter than the large diameter portion, and a small diameter portion that is formed between the large diameter portion and the medium diameter portion so as to have a smaller diameter than the medium diameter portion, in a state before being disposed in the cylinder,
wherein, at the one end on the side close to the tip portion of the piston rod, an inner peripheral surface is inclined toward a piston main body side from the large-diameter surface portion to the small-diameter surface portion of the stepped portion,
wherein the inner peripheral surface at the one end of the piston band is separated from a stepped surface of the stepped portion, and
wherein at the one end of the piston band, both an inner peripheral surface end and an outer peripheral surface end are separated from the small-diameter surface portion.

2. The shock absorber according to claim 1 , wherein the piston main body includes a protrusion portion and a recess portion provided along an axial direction at the outer peripheral portion on which the piston band is mounted, a first protrusion portion is formed at the one end on the side close to the tip portion of the piston rod, and the small-diameter surface portion is formed on the side close to the tip portion of the piston rod, of the first protrusion portion, and
at the one end of the piston band, the inner peripheral surface is inclined from the first protrusion portion toward the small-diameter surface portion.

3. The shock absorber according to claim 2 , wherein a second protrusion portion is formed at the other end on the side far from the tip portion, and
at the other end of the piston band, an outer peripheral surface is inclined toward the second protrusion portion, and the inner peripheral surface is in contact with the recess portion adjacent to the second protrusion portion.

4. The shock absorber according to claim 2 , wherein the first protrusion portion has a protrusion height lower than protrusion heights of other protrusion portions.

5. The shock absorber according to claim 2 , wherein the first protrusion portion has an axial dimension larger than axial dimensions of other protrusion portions.

6. The shock absorber according to claim 1 , wherein the piston band is formed of a material that is a low friction material and has a characteristic in which a friction coefficient increases when a surface pressure is low.

7. The shock absorber according to claim 6 , wherein a contact area between the piston band and the inner peripheral portion of the cylinder becomes larger when a radial force acts on the piston rod than when a radial force does not act on the piston rod.

8. The shock absorber according to claim 1 , wherein a contact area between the piston band and the inner peripheral portion of the cylinder becomes larger when a radial force acts on the piston rod than when a radial force does not act on the piston rod.

9. A shock absorber comprising:
a bottomed cylinder-shaped cylinder in which a working fluid is enclosed;
a piston rod having a base end portion that is inserted into the cylinder, and a tip portion that protrudes out of the cylinder;
a piston that is fixed to a base end portion side of the piston rod and defines an inside of the cylinder into a one-side chamber and an other-side chamber; and
a rod guide provided on a side opposite to a bottom portion of the cylinder to guide the piston rod,
wherein the piston includes:
a piston main body that is fixed to the piston rod; and
a piston band that is provided on an outer peripheral portion of the piston main body and is in sliding contact with an inner peripheral portion of the cylinder,
wherein the piston main body has a stepped portion including a large-diameter surface portion, a stepped surface portion, and a small-diameter surface portion, at one end on a side close to a tip portion of the piston rod, of an outer peripheral portion on which the piston band is mounted,
wherein the piston band has, at an outer peripheral portion thereof,
a small diameter portion;
a first projecting portion that is provided to protrude from the small diameter portion on the side close to the tip portion of the piston rod with respect to the small diameter portion; and
a second projecting portion that is provided to protrude from the small diameter portion on a side far from the tip portion with respect to the small diameter portion and is smaller than the first projecting portion, in a state before being disposed in the cylinder,
wherein, at one end of the piston band on the side close to the tip portion of the piston rod, an inner peripheral surface is inclined from the large-diameter surface portion toward the small-diameter surface portion,
wherein the inner peripheral surface at the one end of the piston band is separated from a stepped surface of the stepped portion, and
wherein at the one end of the piston band, both an inner peripheral surface end and an outer peripheral surface end are separated from the small-diameter surface portion.

10. The shock absorber according to claim 9 , wherein the piston main body includes a protrusion portion and a recess portion provided along an axial direction at the outer peripheral portion on which the piston band is mounted, and a first protrusion portion is formed at one end on the side close to the tip portion of the piston rod, and
at one end of the piston band, the inner peripheral surface is inclined from the first protrusion portion toward the small-diameter surface portion.

11. The shock absorber according to claim 10 , wherein a second protrusion portion is formed at the other end on the side far from the tip portion, the small-diameter surface portion is formed on the side close to the tip portion of the piston rod, of the first protrusion portion, and
at the other end of the piston band, an outer peripheral surface is inclined toward the second protrusion portion, and the inner peripheral surface is in contact with the recess portion adjacent to the second protrusion portion.

Assignees

• Hitachi Astemo Ltd

Inventors

• Yamada Kazuya
• Yamada Kentaro
• Nakagawa Reiji
• Sato Hiroyasu
• Matsumura Sadatomo
• Takagi Wataru

Classifications

• F16F2234/02

  cylindrical · CPC title

• F16F2232/08

  Linear · CPC title

• F16F2230/30

  Sealing arrangements · CPC title

• F16F2222/12

  Fluid damping · CPC title

• F16F9/185

  Bitubular units (where compression of gas leads to a clear spring action F16F9/062) · CPC title