Double-tube damper and bottom valve assembly

Abstract

The invention provides a double-tube damper and a bottom valve assembly. In general, the present invention provides a dual tube damper having an outer tube and an inner tube such that a chamber for oil is formed between the inner tube and the outer tube. The piston and rod move within the inner tube in response to a driving condition. The bottom valve assembly is located between the inner tube and the outer tube. The bottom valve assembly includes a cylinder end having a first end and a second end. An opening extends through the cylinder end and is in fluid communication between the inner tube and the outer tube. The first end of the bottom valve assembly defines a sealing surface, and the access disc is mounted adjacent to the sealing surface. The sealing surface has a reduced portion. A compression relief valve assembly is positioned adjacent the second end. When the pressure in the inner tube is low, a gap between the sealing surface and the inlet disc allows for an additional oil flow path through the bottom valve assembly. When the pressure in the inner tube increases, the gap is gradually closed by the inlet disc.

Description

Technical Field

[0001] The present invention relates generally to dampers and, in particular, to vehicle dampers. Background Art

[0002] The most common type of suspension damper used in modern vehicles is the twin-tube passive hydraulic damper. This type of damper is made of two concentric tubes. The inner tube is the working cylinder in which the piston moves, while the outer tube is the housing and the oil reservoir. A fixed hydraulic valve called a foot valve is located in the lower part of the damper between the two concentric tubes. When the damper moves, the foot valve controls the flow of oil between the tubes of the cylinder and the reservoir chamber.

[0003] In a typical twin tube damper, the base valve assembly has a valve body (also called a cylinder end) and a pressure relief valve that is used to control the flow of oil from the inner or cylinder tube to the outer tube or reservoir chamber during the compression stroke. An intake disc present on the opposite side of the valve body acts as a check valve that allows rapid refilling of the cylinder's tube with oil during the rebound (extension) stroke.

[0004] In a conventional foot valve, the inlet disc serves only as a check valve. Its purpose is to prevent the oil from flowing through the external port at the cylinder end during damper compression and to enable it to effectively refill the cylinder during extension. The check valve can consist of a single inlet disc or contain several inlet discs. It can also be equipped with an additional spring. The first disc from the cylinder end can be equipped with a slot (fixed orifice).

[0005] The cylinder ends are equipped with flat circumferential seats to ensure proper non-return valve sealing during compression. Under the influence of pressure, the inlet discs are pressed against them and oil flow is impossible. It is important that in this case all seats are nominally in the same plane.

[0006] Some vehicle applications require high damping forces in both the rebound and compression strokes. However, excessive damping in compression can adversely affect the isolation of the vehicle body from low amplitude inputs such as slow speeds, small waves on major roads, and road particles.

[0007] The base valve of the present invention helps improve ride quality and reduce harshness. The variable bleed allows shaping of the damping characteristics during the initial phase of the compression movement, resulting in smoother damper operation and improved ride feel. Summary of the invention

[0008] In general, the present invention provides a twin tube damper having an outer tube and an inner tube, thereby forming a chamber for oil and gas between the inner tube and the outer tube. The piston and rod move in the inner tube in response to driving conditions. A bottom valve assembly is located between the inner tube and the outer tube. The bottom valve assembly includes a cylinder end having a first end and a second end. An opening extends through the cylinder end and is fluidly connected between the inner tube and the outer tube. The first end of the bottom valve assembly defines a sealing surface, and an inlet disc is mounted adjacent to the sealing surface. The sealing surface has a lowered portion. A compression relief valve assembly is positioned adjacent to the second end. When the pressure in the inner tube and the outer tube is low, the gap between the sealing surface and the inlet disc allows an additional oil flow path through the bottom valve assembly. When the pressure in the inner tube increases, the gap is gradually closed by the inlet disc.

[0009] These and other features and advantages of the present invention will become more apparent to those skilled in the art through the detailed description of the preferred embodiments. The drawings accompanying the detailed description are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a partially cutaway perspective view of a twin-tube damper of the present invention.

[0011] Figure 2 is an exploded view of the bottom valve assembly of the present invention.

[0012] Figure 3 is a cross-sectional view of the foot valve assembly.

[0013] Figure 4 is an enlarged view of the center seat of the foot valve assembly.

[0014] Figure 5 is a cross-sectional view of the foot valve assembly.

[0015] Fig. 6A It is a graph illustrating the relationship between the flow rate and the pressure characteristic of the present invention.

[0016] Figure 6B is a graph showing the force versus displacement characteristics of a damper including the base valve assembly of the present invention. DETAILED DESCRIPTION

[0017] The twin tube damper with variable bleed bottom valve of the present invention is generally shown at 10. In addition to the variable bleed bottom valve, the twin tube damper shown at 12 is a well known damper. It has an outer tube 14 and an inner tube or cylinder tube 16. A piston 18 and a rod 20 move within the inner tube in response to driving conditions. A top seal assembly 21 closes the two tubes 14 and 16. A lower mounting 22 is shown, and it should be understood that an upper mounting (not shown) is also provided to mount the twin tube damper in a vehicle.

[0018] Reference Figures 1 to 5 , the bottom valve assembly of the present invention is generally shown at 24. The bottom valve assembly 24 has a cylinder end 26. A compression relief valve assembly 28, including several discs and a relief disc 30 having a groove, is mounted adjacent to the cylinder end 26. The discs are thick deflection discs, and the grooves are relatively narrow, which is a standard for providing high damping and good main travel. A rebound check valve or inlet disc 32 is mounted to the opposite side of the cylinder end 26. The inlet disc 32 has a groove 33 for oil flow. As illustrated, bolts 34 and nuts 36 connect them together to form the bottom valve assembly 24.

[0019] Reference Figure 3 and Figure 4 , the bottom valve assembly 24 includes windows 38 and 40 and holes 44 and 46. Figure 5 As shown, windows 38 and 40 and holes 44 and 46 allow oil to flow between tubes 14 and 16. Generally, during the rebound stroke, oil flows through windows 38 and 40. During the compression stroke, oil flows through holes 44 and 46.

[0020] The bottom valve assembly 24 has a surface generally forming a seat 39 having an outer seat 41, an inner seat 43 and an intermediate seat 45. The intermediate seat 45 of the bottom valve assembly 24 has a lowered portion or gap 48 relative to the inner seat 43 and the outer seat 41 so that in the unloaded state, there is a gap 48 between the seat and the inlet disc 32, see Figure 4 The gap 48 defines a variable orifice.

[0021] like Figure 5 As shown, during the rebound stroke, the oil flow is generally shown at 50 and flows primarily through the windows 38, 40 by deflecting the inlet disc 32. This is conventional foot valve operation and the gap 48 has no significant effect on the damper operation during the rebound stroke.

[0022] As the damper is compressed, the pressure in the inner tube 16 between the base valve assembly 24 and the piston 18 rises. In effect, oil flows from the compression chamber to the reservoir chamber, as generally shown at 52. The flow path 54 is a conventional flow path and includes flow through the slot 33 of the inlet disc 32, the holes 44 and 46 of the cylinder end 26, and the compression relief valve assembly 28. Additionally, the oil flows through the gap 48 and then through the windows 38, 40, as shown by arrows 55. This condition isolates the vehicle from road conditions, such as, for example, rough road surfaces. However, as the pressure differential between the cylinder and the reservoir increases, the inlet disc 32 flexes toward the gap 48, thereby continuously reducing the gap 48 until the gap 48 is fully closed.

[0023] When the pressure reaches a preset value, the disk of the compression relief valve assembly 28 begins to deflect. If the velocity and pressure are low, the oil flow 54 is achieved only through the orifice disk 30, and the disk of the compression relief valve assembly 28 does not deflect. In this case, the effect of the flow 55 on the total flow 52 is significant. Therefore, for pressures / velocities below the opening pressure / velocity of the disk of the compression relief valve assembly 28, the effect of the variable relief is most significant.

[0024] When a standard compression relief valve assembly 28 with narrow slots and many thick deflector discs is used, high damping and good main ride are provided. However, isolation and ride comfort are generally worse. The disclosed invention provides additional flow through the base valve assembly 24 to improve vehicle ride in low pressure and low speed conditions. The additional oil flow through the gap 48 occurs at the beginning of the compression stroke and flows at low speeds to improve vehicle ride. However, this oil flow path is intended to close as speed or stroke amplitude rises and pressure increases.

[0025] This allows a variable oil flow to be released through the base valve assembly 24 during the initial stages of damper compression until a certain pressure is achieved in the cylinder. As pressure increases, the inlet disc 32 is gradually deflected toward the intermediate seat 45. The flow rate depends on this pressure, as Fig. 6A shown. Figure 6B The effect of the proposed technique on the damper force versus displacement characteristics is shown.

[0026] The intermediate seat 45 of the base valve assembly 24 having a lowered portion or gap 48 relative to the inner seat 43 and the outer seat 41 provides additional oil flow at low speeds and pressures to achieve a smoother ride. When the twin tube damper 10 of the present invention is in an unloaded state, that is, when the pressure is below a predetermined value, there is a gap 48 between the seat and the inlet disc 32. The gap 48 defines a variable orifice to allow additional oil flow to dampen vehicle ride characteristics.

[0027] The foregoing invention has been described in accordance with relevant legal standards. Therefore, the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiments may become apparent to those skilled in the art and do fall within the scope of the invention. Therefore, the scope of legal protection afforded this invention can only be determined by studying the following claims.

Claims

1. A twin-tube damper, comprising: External pipe; an inner tube located within the outer tube so as to form a chamber between the inner tube and the outer tube; the inner tube and the outer tube being configured to contain oil; a piston and a rod adapted to move within the inner tube in response to driving conditions; a base valve assembly positioned between the inner tube and the outer tube, the base valve assembly including a cylinder end having a first end and a second end, the base valve assembly having an opening extending through the base valve assembly, the opening being in fluid communication between the inner tube and the outer tube, the first end of the cylinder end defining a sealing surface, an inlet disc mounted adjacent the sealing surface, and a compression relief valve assembly positioned adjacent the second end; The sealing surface of the cylinder end has a lowered portion; Thus, when the pressure in the inner tube is low, the gap between the sealing surface at the lowered portion and the inlet disc allows an additional oil flow path through the bottom valve assembly, and when the pressure in the inner tube increases, the gap is gradually closed by the inlet disc.

2. The twin-tube damper according to claim 1, wherein: The inlet pan includes grooves for transferring oil between the inner tube and the outer tube. 3 . The twin tube damper of claim 1 , further comprising a top seal enclosing the inner tube and the outer tube.

4. The twin-tube damper according to claim 3, wherein: The bottom valve assembly is positioned opposite the top seal.

5. The twin-tube damper according to claim 1, wherein: The sealing surface includes an outer seat, an inner seat and a middle seat, and the middle seat is lower than the outer seat and the inner seat to define the gap.

6. The twin-tube damper according to claim 5, wherein: The entry tray is mounted adjacent the outer seat, the inner seat, and the intermediate seat.

7. The twin tube damper of claim 1 further comprising fasteners connecting the inlet plate and the compression relief valve assembly to the cylinder end.

8. The twin-tube damper according to claim 1, wherein: The openings include windows and holes.

9. The twin-tube damper according to claim 8, wherein: The window has sides and the hole is cylindrical.

10. The twin-tube damper according to claim 1, wherein: The compression relief valve assembly includes a plurality of discs and a relief disc having a groove.

11. The twin-tube damper according to claim 5, wherein: The twin tube damper has a rebound stroke, wherein as the pressure difference between the inner tube and the outer tube increases due to the movement of the piston, the oil flows through the gap and the inlet plate bends toward the middle seat, thereby continuously reducing the gap until the gap is completely closed.

12. A bottom valve assembly for installation in a twin-tube damper, the bottom valve assembly comprising: a cylinder end having a first end and a second end, the cylinder end of the base valve assembly having a first end defining a sealing surface, the base valve assembly having an opening extending therethrough, the opening being configured to regulate fluid flow, the first end of the cylinder end defining a sealing surface, an entry disk mounted adjacent the sealing surface, and a compression relief valve assembly positioned adjacent the second end; The sealing surface of the bottom valve assembly has a lowered portion that creates a gap; Thus, the gap between the sealing surface at the lowered portion and the inlet disc allows an additional oil flow path through the base valve assembly, and the gap is adapted to be gradually closed by the inlet disc by a pressure increase adjacent the inlet disc.

13. The bottom valve assembly according to claim 12, wherein: The inlet pan includes a groove configured to communicate oil through the base valve assembly.

14. The bottom valve assembly according to claim 12, wherein: The sealing surface includes an outer seat, an inner seat and a middle seat, and the middle seat is lower than the outer seat and the inner seat to define the gap.

15. The bottom valve assembly according to claim 14, wherein: The entry tray is mounted adjacent the outer seat, the inner seat, and the intermediate seat.

16. The base valve assembly of claim 12, further comprising fasteners connecting the inlet disc and the compression relief valve assembly to the cylinder end.

17. The bottom valve assembly according to claim 12, wherein: The openings include windows and holes.

18. The bottom valve assembly according to claim 17, wherein: The window has sides and the hole is cylindrical.

19. The bottom valve assembly of claim 14, further comprising a twin tube damper having an inner tube and an outer tube, the twin tube damper having a compression stroke, wherein: As the pressure differential between the inner and outer tubes increases due to the movement of the piston, oil flows through the opening and through the gap, and the inlet plate bends toward the middle seat, thereby continuously reducing the gap until the gap is completely closed as the pressure in the twin tube damper increases.

20. The bottom valve assembly of claim 19, further comprising a top seal enclosing the inner tube and the outer tube.

Images