US-12618448-B2 - Piston for shock absorber with optimized bleed range and tuneability

US12618448B2US 12618448 B2US12618448 B2US 12618448B2US-12618448-B2

Abstract

A shock absorber for a vehicle including a pressure tube, a piston rod, and a piston assembly. The piston assembly includes a first disc, a second disc, and a piston body. The piston body includes first and second surfaces and first and second fluid passages. The piston body further includes a first circumferential land surrounding the first fluid passage and a second circumferential land surrounding the second fluid passage. The first circumferential land is located a first distance from the first surface. The first disc is selectively driven into engagement with the first circumferential land. The second circumferential land is located a second distance from the first surface. The second circumferential land is between the first surface and the first circumferential land. The second disc includes a first portion in sealing engagement with the second circumferential land and a second portion spaced apart from the piston body.

Inventors

Franky Montagna
Werner Bosmans

Assignees

ADVANCED SUSPENSION TECHNOLOGY LLC

Dates

Publication Date: 20260505
Application Date: 20230508

Claims (14)

1 . A shock absorber for a vehicle comprising: a pressure tube; a piston rod extending within the pressure tube along a longitudinal axis; a piston assembly slidably fitted in the pressure tube for movement along the longitudinal axis, the piston assembly coupled to the piston rod and separating the pressure tube into a first working chamber and a second working chamber, the piston assembly comprising: a first disc; a second disc; and a piston body, the piston body comprising: a first surface on a first side of the piston body; a second surface on a second side of the piston body; a first fluid passage extending through the piston body; a first circumferential land surrounding the first fluid passage, wherein the first circumferential land is located a first distance away from the first surface and a greater distance away from the second surface, and wherein the first disc is selectively driven into engagement with the first circumferential land; a circumferential wall extending from the first surface of the piston body and surrounding the first fluid passage, the circumferential wall terminating at a distal end with the first circumferential land; and a rib extending from the circumferential wall away from the first fluid passage; a second fluid passage extending through the piston body; and a second circumferential land surrounding the second fluid passage, wherein the second circumferential land is located a second distance away from the first surface, wherein the second distance is less than the first distance, wherein the second circumferential land is between the first surface and the first circumferential land, and wherein the second disc includes a first portion in sealing engagement with the second circumferential land and a second portion spaced apart from the piston body.
2 . The shock absorber of claim 1 , wherein the second circumferential land is parallel to the first surface and the second surface.
3 . The shock absorber of claim 1 , wherein the first circumferential land is parallel to the first surface.
4 . The shock absorber of claim 1 , wherein the second circumferential land is parallel to the first surface.
5 . The shock absorber of claim 1 , further comprising an angled notch in fluid communication with the second fluid passage.
6 . The shock absorber of claim 5 , wherein the second fluid passage is a continuously open bleed passage and the angled notch is configured to increase a cross-sectional area of the continuously open bleed passage.
7 . The shock absorber of claim 1 , further comprising a wall extending from the first surface of the piston body, the wall terminating at a distal end with a land, the land planar with the first circumferential land.
8 . A shock absorber for a vehicle comprising: a pressure tube; a piston rod extending within the pressure tube along a longitudinal axis; a piston assembly slidably fitted in the pressure tube for movement along the longitudinal axis, the piston assembly coupled to the piston rod and separating the pressure tube into a first working chamber and a second working chamber, the piston assembly comprising: a first disc; a second disc; and a piston body, the piston body comprising: a first surface on a first side of the piston body; a second surface on a second side of the piston body; a first fluid passage extending through the piston body; a first circumferential land surrounding the first fluid passage, wherein the first circumferential land is located a first distance away from the first surface and a greater distance away from the second surface, and wherein the first disc is selectively driven into engagement with the first circumferential land; a second fluid passage extending through the piston body; a second circumferential land surrounding the second fluid passage, wherein the second circumferential land is located a second distance away from the first surface, wherein the second distance is less than the first distance, wherein the second circumferential land is between the first surface and the first circumferential land, and wherein the second disc includes a first portion in sealing engagement with the second circumferential land and a second portion spaced apart from the piston body; and a further population of lands on the first surface of the piston body, the further population of lands configured to support a surface of the second disc and permits flow of fluid beneath the surface of the second disc, the piston body further comprising a center hole and a hub surrounding the center hole, and wherein the population of lands are located radially between the hub and the second circumferential land.
9 . A shock absorber for a vehicle, the shock absorber comprising: a pressure tube; a piston rod extending within the pressure tube along a longitudinal axis; and a piston body slidably fitted in the pressure tube for movement along the longitudinal axis, the piston body comprising: a first surface on a first side of the piston body; a second surface on a second side of the piston body, the second surface opposite the first surface; a first fluid passage extending through the piston body; a first circumferential wall extending a first distance away from the first surface and a greater distance away from the second surface, the first circumferential wall surrounding the first fluid passage and providing a first sealing surface, wherein the first sealing surface is configured to selectively seal with a portion of a first disc; and a second circumferential wall extending a second distance away from the first surface and a greater distance away from the second surface, wherein the second distance is less than the first distance, the second circumferential wall surrounding a second fluid passage and providing a second sealing surface, the second sealing surface longitudinally between the first surface and the first sealing surface, wherein the second sealing surface is configured to seal with a portion of a second disc, the piston body further comprising a rib extending from the first circumferential wall away from the first fluid passage.
10 . The shock absorber of claim 9 , wherein the first sealing surface and the second sealing surface are parallel to the first surface and the second surface.
11 . The shock absorber of claim 9 , the piston body further comprising a flow guiding feature between the second circumferential wall and the second fluid passage, wherein the second fluid passage is a bleed passage and the flow guiding feature is configured to increase a cross-sectional area of the bleed passage.
12 . The shock absorber of claim 9 , the piston body further comprising a wall extending from the first surface of the piston body, the wall terminating at a distal end with a land, the land planar with the first sealing surface.
13 . The shock absorber of claim 9 , the piston body further comprising a population of lands on the first surface of the piston body, the population of lands configured to support a surface of the second disc and permits flow of fluid beneath the surface of the second disc.
14 . A shock absorber for a vehicle, the shock absorber comprising: a pressure tube; a piston rod extending within the pressure tube along a longitudinal axis; and a piston body slidably fitted in the pressure tube for movement along the longitudinal axis, the piston body comprising: a first surface on a first side of the piston body; a second surface on a second side of the piston body, the second surface opposite the first surface; a first fluid passage extending through the piston body; a first circumferential wall extending a first distance away from the first surface and a greater distance away from the second surface, the first circumferential wall surrounding the first fluid passage and providing a first sealing surface, wherein the first sealing surface is configured to selectively seal with a portion of a first disc; and a second circumferential wall extending a second distance away from the first surface and a greater distance away from the second surface, wherein the second distance is less than the first distance, the second circumferential wall surrounding a second fluid passage and providing a second sealing surface, the second sealing surface longitudinally between the first surface and the first sealing surface, wherein the second sealing surface is configured to seal with a portion of a second disc, the piston body further comprising a further population of lands on the first surface of the piston body, the further population of lands configured to support a surface of the second disc and permits flow of fluid beneath the surface of the second disc, the piston body further comprising a center hole and a hub surrounding the center hole, and wherein the further population of lands are located radially between the hub and the second sealing surface.

Description

FIELD The present disclosure relates to automotive shock absorbers/dampers. More particularly, the present disclosure relates to components of shock absorbers/dampers that provide optimized bleed range and tunability. BACKGROUND The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Shock absorbers are typically used in conjunction with automotive suspension systems or other suspension systems to absorb unwanted vibrations that occur during movement of the suspension system. In order to absorb these unwanted vibrations, automotive shock absorbers are generally connected between the sprung (body) and the unsprung (suspension/drivetrain) masses of the vehicle. The most common type of shock absorbers for automobiles are mono-tube and dual-tube shock absorbers. In the mono-tube shock absorber, a piston is located within a fluid chamber defined by a pressure tube and is connected to the sprung mass of the vehicle through a piston rod. The pressure tube is connected to the unsprung mass of the vehicle. The piston divides the fluid chamber of the pressure tube into a first working chamber and a second working chamber. The piston includes compression valving that limits the flow of hydraulic fluid from the second working chamber to the first working chamber during a compression stroke. The piston also includes rebound valving that limits the flow of hydraulic fluid from the first working chamber to the second working chamber during a rebound or extension stroke. Because the compression valving and the rebound valving have the ability to limit the flow of hydraulic fluid, the shock absorber is able to produce a damping force that counteracts oscillations/vibrations, which would otherwise be transmitted from the unsprung mass to the sprung mass. Together, the compression and rebound valving assemblies for the shock absorber have the function of controlling fluid flow between the upper and second working chambers of the shock absorber. By controlling the fluid flow between the two working chambers, a pressure drop is built up between the two working chambers and this contributes to the damping forces of the shock absorber. The compression and rebound valving and the check valve assemblies can be used to tune the damping forces to control ride and handling as well as noise, vibration, and harshness. While there are various features and elements to tune a shock absorber, a need exists for improved tunability and repeatability of shock absorbers. SUMMARY This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. In accordance with one aspect of the subject disclosure, an improved piston design for use in a shock absorber for a vehicle is provided. The piston includes lands surrounding inlets of one or more bleed passages. The lands are configured to support one or more bleed discs. The lands minimize the risk of small particles (contamination) being stuck under bleed discs and creating a leak path. The lands improve the sealing capabilities of the bleed disc, creating more repeatable closing behavior results. In some aspects of the subject disclosure, the piston body may increase the available bleed tuning area without compromising on blowoff area by optimizing the use of the area between the bleed inlet and blowoff inlet, such as for example, by providing a notch or flow guiding feature to aid in the flow of hydraulic fluid into the bleed inlet. In some aspects of the subject disclosure, the piston body may include a rib on an outer wall of a blowoff island adjacent to the one or more bleed discs to reduce the contact area between the bleed discs and the piston. Reducing the contact area between bleed discs and piston may increase the repeatability of the open bleed closing behavior. In some aspects of the subject disclosure, the piston may include one or more blowoff lands and one or more support lands in the same plane as the blowoff lands. Due to the presence of the bleed inlets between the blowoff lands in some aspects of the subject disclosure, there may be a gap between the blowoff lands, which may result in the possibility of the blowoff discs being deformed between these blowoff lands, which is detrimental to repeatability of the damping performance of the shock absorber. The support lands provide support for the blowoff discs, which may reduce or prevent deformation of the blowoff discs, which may improve repeatability of the damping performance of the shock absorber. In some aspects of the subject disclosure, the piston body may include one or more continuous or segmented lands radially between the bleed passages and a center hole of the piston body. The lands are configured to allow hydraulic fluid to flow underneath the bleed disc and between the bleed disc and the piston body, which may provide for a zero pressure delta between the top and bottom o