Search

EP-4737759-A1 - SHIM CONTROLLED BI-DIRECTIONAL BLEED

EP4737759A1EP 4737759 A1EP4737759 A1EP 4737759A1EP-4737759-A1

Abstract

The present disclosure relates to a bleed valve assembly (1) for a shock absorber, the bleed valve assembly (1) comprising: a housing (10) comprising a first and a second port (11, 12), said housing (10) adapted to be arranged to a piston rod (110) of a shock absorber comprising a piston rod bleed flow channel in said piston rod (110); a first and a second adjustable bleed valve (21, 22), each adjustable bleed valve (21, 22) adapted to adjust size of a respective first and second primary bleed flow opening (13, 14), and a first and a second shim element arrangement (31, 32) arranged inside said housing (10), each shim element arrangement (31, 32) adapted to, in response to a respective bleed flow (F1, F2), resiliently open a respective first and second auxiliary flow opening (15, 16) from a respective closed state, wherein the bleed valve assembly (1) is adapted to: guide a compression bleed flow (F1) via said first port (11), said first primary flow opening (13) and said first auxiliary flow opening (15) into said piston rod bleed flow channel, and guide a rebound bleed flow (F2), which rebound bleed flow (F2) is received from said piston rod bleed flow channel, via said second primary flow opening (14), said second auxiliary flow opening (16) and said second port (12). A shock absorber and a method adjusting a bleed flow is also disclosed.

Inventors

  • TORSTENSSON, Jonas Peter Olof
  • WALLEN, Magnus Ingemar
  • NORDGREN, Erik Axel

Assignees

  • Öhlins Group AB

Dates

Publication Date
20260506
Application Date
20241030

Claims (15)

  1. A bleed valve assembly (1) for a shock absorber, the bleed valve assembly (1) comprising: a housing (10) comprising a first and a second port (11, 12), said housing (10) adapted to be arranged to a piston rod (110) of a shock absorber comprising a piston rod bleed flow channel in said piston rod (110); a first and a second adjustable bleed valve (21, 22), each adjustable bleed valve (21, 22) adapted to adjust size of a respective first and second primary bleed flow opening (13, 14), and a first and a second shim element arrangement (31, 32) arranged inside said housing (10), each shim element arrangement (31, 32) adapted to, in response to a respective bleed flow (F1, F2), resiliently open a respective first and second auxiliary flow opening (15, 16) from a respective closed state, wherein the bleed valve assembly (1) is adapted to: guide a compression bleed flow (F1) via said first port (11), said first primary flow opening (13) and said first auxiliary flow opening (15) into said piston rod bleed flow channel, and guide a rebound bleed flow (F2), which rebound bleed flow (F2) is received from said piston rod bleed flow channel, via said second primary flow opening (14), said second auxiliary flow opening (16) and said second port (12).
  2. Bleed valve assembly (1) according to claim 1, wherein said first and second shim element arrangement (31, 32) are reconfigurable in terms of shim element size and/or shim element thickness and/or number of shim elements and/or progressive damping behavior, and the housing (10) is adapted in size and shape to house any selection of at least a plurality of different shim element configurations of said first and second shim element arrangement (31, 32).
  3. Bleed valve assembly (1) according to any preceding claims, wherein the housing (10) is adapted to be removably attached to the piston rod (110).
  4. Bleed valve assembly (1) according to any preceding claims, further comprising: a first valve body (41) arranged in said housing (10) and defining a first valve seat for the first shim element arrangement (31), wherein said first valve body (41) defines at least one bleed flow channel adapted to fluidly connect said first port (11) and said first valve seat.
  5. Bleed valve assembly (1) according to any preceding claims, further comprising: a second valve body (42) arranged in said housing (10) and defining a second valve seat for the second shim element arrangement (32), wherein said second valve body (42) defines at least one bleed flow channel adapted to fluidly connect said second valve seat and said second port (12).
  6. Bleed valve assembly (1) according to claim 5, wherein the housing comprises: at least one housing bleed flow channel (19), wherein each housing bleed flow channel (19) is adapted to guide a compression bleed flow (F1) from the first auxiliary bleed flow opening (15), around the second valve body (42), and into the piston rod bleed flow channel (22).
  7. Bleed valve assembly (1) according to claims 4 and any of claims 5-6, further comprising: an intermediate valve body (43) arranged in said housing (10) to separate an internal space of the housing (10) into a compression side space (CFS) and a rebound side space (RFS), wherein the first and second shim element arrangement (31, 32) are each adapted to be sandwiched between the intermediate valve body (43) and a respective valve body (41, 42) of the first and the second valve body (41, 42).
  8. Bleed valve assembly (1) according to any preceding claims, comprising: a through-hole extending in a longitudinal direction coinciding with a stroke axis of said piston rod and defining said first port (11), wherein said first adjustable bleed valve (21) is axially moveable inside said through-hole to adjust size of said first primary bleed flow opening (13), and/or said second adjustable bleed valve (22) is axially moveable inside said through-hole to adjust size of said second primary bleed flow opening (14).
  9. Bleed valve assembly (1) according to any preceding claims, wherein the second adjustable bleed valve (22) comprises: a tubular member (22) comprising: a first tubular end (220), and at least one aperture (221) displaced axially from said first tubular end (220), which at least one aperture (221) is arrangeable to guide said compression bleed flow into said tubular member.
  10. Bleed valve assembly (1) according to any preceding claims, wherein said first and/or said second adjustable bleed valve (21, 22) are adjustable independently of pressure.
  11. Bleed valve assembly (1) according to any preceding claims, wherein said first and second adjustable bleed valve (21, 22) are adjustable independently of one another.
  12. Bleed valve assembly (1) according to any preceding claims, wherein said first and/or second adjustable bleed valve (21, 22) are adjustable from a distance.
  13. Bleed valve assembly (1) according to any preceding claims, further comprising a first and second adjustment element (211, 221), wherein said first adjustable bleed valve (21) is attached to said first adjustment element (211) and said second adjustable bleed valve (22) is attached to said second adjustment element (221), wherein the first adjustment element (211) is adapted to be axially moveable inside said second adjustment element (221).
  14. Shock absorber comprising: a working chamber; a piston positioned on a piston rod, which piston separates the working chamber into a compression chamber (100C) and a rebound chamber (100R), wherein the piston rod comprises a piston rod bleed flow channel fluidly connecting the compression chamber (100C) with the rebound chamber (100R), the shock absorber further comprising: a bleed valve assembly (1) according to any preceding claims.
  15. Method of adjusting a bleed flow in a shock absorber according to claim 14, the method comprising: providing said first and second shim element arrangement (31, 32) with a respective shim element configuration corresponding to a desired damping characteristic of said shock absorber; providing the first and second adjustable bleed valve (21, 22) to respective positions corresponding to said desired damping characteristic, resiliently opening the first auxiliary flow opening (15) from a closed state in response to a compression bleed flow (F1) received via said first port (11) and said first primary flow opening (13) to regulate said compression bleed flow (F1) before entering said piston rod bleed flow channel, and resiliently opening the second auxiliary flow opening (16) from a closed state in response to a rebound bleed flow (F2) received via said piston rod bleed flow channel and said second primary flow opening (14) to regulate said rebound bleed flow (F2) before flowing through said second port (12).

Description

TECHNICAL FIELD The present disclosure relates to a bleed valve assembly for a shock absorber, a shock absorber incorporating the same, and a method for adjusting a bleed flow in a shock absorber. TECHNICAL BACKGROUND Shock absorbers may incorporate adjustable damping assemblies to control the damping force generated by fluid flow within the shock absorber, allowing for varying damping characteristics. These adjustable assemblies often utilize different types of valve arrangements. A common issue with adjustable damping systems, particularly those integrated into piston rods, is that while riders may wish to modify damping settings based on current driving conditions, the assemblies are often difficult to adjust. External adjustment of damping levels in single-tube shocks (via a 'click adjuster') typically involves regulating a bleed adjuster located inside the piston rod of the rear shock. The size of the bleed area, determined by how much the adjuster is opened, primarily influences low-speed damping, while having minimal impact at high shock velocities. On racing motorcycles, a larger bleed area can enhance grip levels, though it often comes at the cost of vehicle stability. However, the traditional single-tube bleed adjuster has the drawback of either affecting both the compression and rebound strokes simultaneously or impacting only the rebound stroke. Accordingly, there is a need for an improved solution. Prior art solutions are disclosed in e.g., EP3786478A1, US11040754B2, US11920656B2, US9273746B2. SUMMARY It is an object of the disclosure to provide an improved solution that alleviates at least some of the mentioned drawbacks within the prior art. A first object of the disclosure is to provide a bleed valve assembly enabling individual adjustment of damping characteristic for compression and rebound respectively. A second object of the disclosure is to provide a bleed valve assembly which facilitates adjustment so as to achieve desired damping characteristic for compression and rebound respectively. A third object of the disclosure is to provide a bleed valve assembly for single-tube shock absorbers with enhanced stability. These, and other objects which will become evident in the following disclosure, are solved by the inventions defined by the claims. The scope of the invention is defined by the claims, whereas preferred embodiments are set forth in the dependent claims. Still further embodiments are listed throughout the description. The inventive concept of the disclosure is based on the insight that both enhanced stability and individual adjustment of low-speed damping for compression and rebound can be realized by adapting a bleed valve assembly with shim element arrangements. By arranging a first shim element arrangement in series with a first adjustable bleed valve, the first shim element arrangement can fine tune a damping characteristic (for e.g., compression) set by the first adjustable bleed valve. Moreover, by arranging a second shim element arrangement in series with a second adjustable bleed valve, the second shim element arrangement can fine tune a damping characteristic (for e.g., rebound) set by the second adjustable bleed valve. Further, the first and second shim element arrangement may serve as respective check valves so as isolate the respective damping fluid flows for compression and rebound, thus promoting individual adjustment of low-speed damping characteristic for compression and rebound. Further, shim element arrangements enables enhanced adjustability as compared to conventional check valves. Further, the bleed valve assembly enhances stability, in particular for single tube shock absorbers. According to a first aspect, a bleed valve assembly for a shock absorber is provided. The bleed valve assembly comprises: a housing comprising a first and a second port, said housing adapted to be arranged to a piston rod of a shock absorber comprising a piston rod bleed flow channel in said piston rod. The bleed valve assembly further comprises a first and a second adjustable bleed valve, each adjustable bleed valve adapted to adjust size of a respective first and second primary bleed flow opening. The bleed valve assembly further comprises a first and a second shim element arrangement arranged inside said housing, each shim element arrangement adapted to, in response to a respective bleed flow, resiliently open a respective first and second auxiliary flow opening from a respective closed state. The bleed valve assembly is adapted to: guide a compression bleed flow via said first port, said first primary flow opening and said first auxiliary flow opening into said piston rod bleed flow channel. The bleed valve assembly is further adapted to: guide a rebound bleed flow, which rebound bleed flow is received from said piston rod bleed flow channel, via said second primary flow opening, said second auxiliary flow opening and said second port. Advantageously, the first shim element arran