shock absorbers

Abstract

Shock absorber (26), comprising: a pressure tube (30) defining a fluid chamber (42); a piston assembly (32) disposed in the fluid chamber (42), the piston assembly (32) dividing the fluid chamber (42) into an upper working chamber (44) and a lower working chamber (46); a main pressure fluid passage (70) extending through the piston assembly (32) between the upper and lower working chambers (44, 46); a main pressure valve assembly (62) engaged with the piston assembly (32), the main pressure valve assembly (62) closing the main pressure fluid passage (70); a main traction fluid passage (72) extending through the piston assembly (32) between the upper and lower working chambers (44, 46); a main pull valve assembly (66) engaged with the piston assembly (32), the main pull valve assembly (66) closing the main pull fluid passage (72); a bleed fluid passage (74) extending through the piston assembly (32) between the upper and lower working chambers (44, 46); a bleed valve assembly (64, 68) engaged with the piston assembly (32) and operable to restrict fluid flow through the bleed fluid passage (74), the bleed valve assembly (64, 68) including a bore disc (96), a closure disc (100), and a rotary disc (98) disposed between the bore disc (96) and the closure disc (100), the closure disc (100) being axially slidable relative to the bore disc (96), the rotary disc (98), and the piston assembly (32), and resiliently deformable relative to the piston assembly (32), and the bore disc (96) including a plurality of holes (104, 106) or a plurality of notches (106') that at least partially define the bleed fluid passage (74) upon axial movement of the closure disc (100).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Utility Patent Application No. 14 / 191,538, filed February 27, 2014, and the benefit of U.S. Provisional Application No. 61 / 786,678, filed March 15, 2013. AREA

[0002] The present disclosure generally relates to automotive dampers or shock absorbers that absorb and damp mechanical shocks. More particularly, the present disclosure relates to a hydraulic valve assembly for the shock absorber that includes two separate relief limiting paths that generate low damping forces at very low piston speeds. Prior art in the present technical field is disclosed in documents JP H09-144 799 A, EP 1 664 579 B1, DE 39 32 669 A1, JP 2007 120 627 A1, JP 2012 021 567 A1, and DE 197 55 994 A1. BACKGROUND

[0003] The information in this section provides only background information related to the present disclosure and may not constitute prior art.

[0004] Shock absorbers are used in conjunction with automotive suspension systems to absorb unwanted vibrations that occur during driving. To absorb these unwanted vibrations, shock absorbers are generally connected between the sprung part (body) and the unsprung part (wheels) of the vehicle. A piston is located within a working chamber defined by a shock absorber pressure tube, with the piston connected to the sprung part of the vehicle by a piston rod. The pressure tube is connected to the unsprung part of the vehicle by one of the methods known in the art.Because the piston can use valves to limit the flow of damping fluid between opposite sides of the piston when the shock absorber is compressed or extended, the shock absorber can generate a damping force that dampens the unwanted vibration that would otherwise be transmitted from the unsprung part to the sprung part of the vehicle. In a twin-tube shock absorber, a fluid surge tank is defined between the pressure tube and the reserve tube. When a full-displacement piston valve system is used, the fluid surge tank is in direct communication with the lower part of the working chamber defined by the pressure tube (the area under the piston). All damping forces generated by the shock absorber are the result of piston valves when a full-displacement valve system is used.The greater the degree to which fluid flow in the shock absorber is restricted by the piston, the greater the damping forces generated by the shock absorber. Thus, a more restricted flow would result in a harsh ride, while a less restricted fluid flow would result in a smooth ride.

[0005] When selecting the amount of damping a shock absorber should provide, at least three vehicle performance characteristics are considered. These three characteristics are ride comfort, handling, and roadholding. Ride comfort is often a function of the spring rate for the vehicle's main springs, as well as the spring rate for the seat and tires, and the damping coefficient of the shock absorber. For optimal ride comfort, a relatively low damping force or a smooth ride is preferred.

[0006] Handling behavior is related to the variation in the vehicle's attitude (i.e., turning around the longitudinal, vertical, and lateral axes). For optimal handling, relatively large damping forces, or a hard ride, are required to prevent rapid changes in the vehicle's attitude during cornering, acceleration, and braking.

[0007] Finally, roadholding is generally a function of the degree of contact between the tires and the ground. Optimized roadholding requires large damping forces, or a hard ride, when driving on irregular surfaces to avoid loss of contact between the wheel and the ground for excessively long periods.

[0008] Different types of shock absorbers have been developed to produce the desired damping forces related to various vehicle performance characteristics. Shock absorbers are designed to provide different damping characteristics depending on the speed or acceleration of the piston in the pressure tube. Due to the exponential relationship between pressure drop and flow rate, achieving a damping force at relatively low piston speeds, especially at speeds close to zero, is a difficult task. Low-speed damping force is important for handling, as most handling events are controlled at slow vehicle body speeds.

[0009] Various prior art systems for tuning shock absorbers during slow piston movement create a fixed slow bleed bore, creating a bleed passage that is always open across the piston. This bleed bore can be created either using bore notches positioned on the flexible disc adjacent to the sealing surface or by using bore notches directly in the sealing surface itself. The limitation of these designs is that the damping force generated is not a function of the shock absorber's internal pressures because the bore has a constant cross-sectional area. To achieve slow control using these open bore notches, the bore notches must be sufficiently small to create restriction at relatively low speeds. When this is met, the slow fluid circuit of the valve system operates over a very narrow speed range.Therefore, the secondary or higher-speed valves are activated at a lower speed than desired. Activating the secondary valves at relatively low speeds creates roughness because, due to the shape of the fixed bleed hole circuit, the force-velocity characteristic has a completely different shape than the high-speed circuit.

[0010] Prior art attempts to address the problems with fixed-bore bleed valves and thus eliminate harshness during slow piston movements have included incorporating a variable-bore bleed valve circuit. As piston speed increases, the variable-bore flow area would also increase, providing a smoother transition to the secondary valves. These prior art variable-bore bleed valve circuits are typically located on the outer periphery of the flexible valve disc and thus depend on the disc diameter to determine the rate at which the flow area increases. As the flexible disc diameter increases, it becomes more difficult to control the rate at which the bore flow area increases.Because the flow area is increased by deflection of the variable bore bleeder disc, a small deflection in a large-diameter variable bore bleeder disc provides a rapid increase in the flow area of ​​the bleeder bore. This rapid increase in flow area complicates the coordination between the low-speed valve circuit and the secondary or high-speed valve circuit.

[0011] Other prior art systems have developed bleed-hole valve circuits integrated with the medium / high-speed valve systems. Integrating the low-speed circuit with the medium / high-speed circuit creates a system in which tuning the low-speed circuit affects the medium / high-speed circuit, and tuning the medium / high-speed circuit affects the low-speed circuit.

[0012] The ongoing development of shock absorbers includes the development of a valve system that can provide a smooth transition between the low-speed valve circuit and the secondary or high-speed valve circuit. The smooth transition between these two circuits helps reduce and / or eliminate any roughness during the transition. In addition to the smooth transition, the development of these systems also focused on separating these two circuits to allow each circuit to be tuned independently. SUMMARY

[0013] The present disclosure provides a method for independently tuning damping forces at slow piston speeds to improve the slow damping characteristics of the shock absorber. The present disclosure includes a separate slow variable bleed bore circuit that is separate from medium / high speed or secondary valving systems. Additionally, the present disclosure includes a pair of fluid flow paths, one of the flow paths closing at a specific piston speed to tune the slow damping characteristics of the shock absorber. Therefore, the object of the invention is to improve the tunability of the shock absorber.

[0014] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS

[0015] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Fig. 1 is an illustration of a motor vehicle incorporating the valve systems according to the present disclosure; Fig. 2 is a side view, partially in cross section, of a shock absorber incorporating the valve systems according to the present disclosure; Fig. 3 is an enlarged side view of the piston group incorporating the valve systems according to the present disclosure; Fig. 4 is a plan view of the Fig. 3 piston shown; Fig. 5a and Fig. 5b are cross-sectional views defining various flow passages that define the slow bleed circuits according to the present disclosure; Fig. 6a and Fig. 6b are plan views of two different bore discs that can be used in the slow drain circuits; Fig. 7 is a side view in cross section showing a slow bleed circuit according to another embodiment of the present disclosure; and Fig. Figure 8 is an exploded view of the closure disc shown in Fig. 7 is shown; Fig. 9 is a side view in cross section showing a slow bleed circuit according to another embodiment of the present disclosure; and Fig. 10A-10D are side views in cross section showing the various flow passages connecting the slow discharge circuits according to the Fig. 9 shown embodiment.

[0016] Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0017] The following description is merely exemplary in nature and should not limit the present disclosure, application, or uses.

[0018] Referring now to the drawings, in which like reference characters designate like or corresponding parts throughout the several views, Fig. 1, a vehicle is illustrated incorporating a suspension system with the independent variable dump system according to the present disclosure, generally designated by the reference numeral 10. The vehicle 10 includes a rear suspension 12, a front suspension 14, and a body 16. The rear suspension 12 has a transversely extending rear axle assembly (not shown) configured to operably support the rear wheels 18 of the vehicle. The rear axle assembly is operably connected to the body 16 by two shock absorbers 20 and two coil springs 22. Likewise, the front suspension 14 includes a transversely extending front axle assembly (not shown) operably supporting the front wheels 24 of the vehicle. The front axle assembly is operably connected to the body 16 by a second pair of shock absorbers 26 and two coil springs 28.Shock absorbers 20 and 26 serve to dampen the relative movement of the unsprung portion (i.e., front 12 and rear 14 suspensions, respectively) and the sprung portion (i.e., body 16) of vehicle 10. Although vehicle 10 is illustrated as a passenger vehicle having a front and rear axle assembly, shock absorbers 20 and 26 may be used with other types of vehicles and / or in other types of applications, such as vehicles that include independent front and / or independent rear suspension systems. Further, the term "shock absorber," as used herein, is intended to refer to dampers generally and thus includes McPherson struts.

[0019] With reference now to Fig. 2, the shock absorber 26 is shown in more detail. While Fig. 2 shows only the shock absorber 26, it is clear that the shock absorber 20 also includes the variable bleed bore valves according to the present invention, which is described below for shock absorber 26. The shock absorber 20 differs from the shock absorber 26 in the manner in which it is designed to connect the sprung and unsprung parts of the vehicle 10. The shock absorber 26 is in Fig. 2 as a monotube shock absorber. It is within the scope of the present disclosure to incorporate the open-drain piston assembly into twin-tube shock absorbers or any other type of shock absorber known in the art. The shock absorber 26 includes a pressure tube 30, a piston assembly 32, and a piston rod 34.

[0020] The pressure tube 30 defines a fluid chamber 42. The piston assembly 32 is slidably disposed within the pressure tube 30 and divides the fluid chamber 42 into an upper working chamber 44 and a lower working chamber 46. A seal 48 is disposed between the piston assembly 32 and the pressure tube 30 to allow sliding movement of the piston assembly 32 with respect to the pressure tube 30 without creating undue frictional forces, as well as to separate the upper working chamber 44 from the lower working chamber 46. The piston rod 34 is attached to the piston assembly 32 and extends through the upper working chamber 44 and through an upper end cap 50 that closes the upper end of the pressure tube 30. A sealing system 52 seals the interface between the upper end cap 50, the pressure tube 30, and the piston rod 34. The end of the piston rod 34 opposite the piston assembly 32 is, in the preferred embodiment, designed to be attached to the suspended part of the vehicle 10.Valves in the piston assembly 32 control the movement of fluid between the upper working chamber 44 and the lower working chamber 46 during movement of the piston assembly 32 in the pressure tube 30. Because the piston rod 34 extends only through the upper working chamber 44 and not the lower working chamber 46, movement of the piston assembly 32 with respect to the pressure tube 30 causes a difference between the amount of fluid displaced in the upper working chamber 44 and the amount of fluid displaced in the lower working chamber 46. This difference in the amount of fluid displaced is known as the "rod volume," and this is compensated for using a floating piston 54, as is well known in the art. While the shock absorber 26 is illustrated as a monotube shock absorber, it is within the scope of the present invention to use a piston assembly 32 in a dual-tube design shock absorber that includes a bottom valve, if desired.The lower end of the pressure tube 30 is closed by an end cap 56, which in the preferred embodiment is designed to be connected to the unsprung part of the vehicle 10.

[0021] The present disclosure relates to a full-flow piston assembly 32 including variable-bore valves for both the rebound and compression strokes, independent of the medium / high-speed valves. The piston assembly 32 provides an independent, tunable smooth transition between the low-speed valves and the medium / high-speed valves in both a compression and rebound motion of the shock absorber 26. The damping characteristics for both the rebound (extension) and compression motions for the shock absorber 26 are determined by the piston assembly 32, eliminating the need for a base valve assembly.

[0022] With reference now to Fig. 3, Fig. 5A and Fig. 5B, the piston assembly 32 includes a piston body 60, a main pressure valve assembly 62, a bleed pressure valve assembly 64, a main pull valve assembly 66, and a bleed pull valve assembly 68. The piston body 60 is attached to the piston rod 34 and defines main pressure fluid passages 70, a plurality of main pull fluid passages 72, and a plurality of bleed fluid passages 74. The piston body 60 bears against the bleed pressure valve assembly 64, which bears against a shoulder formed on the piston rod 34. The piston body 60 also bears against the bleed pull valve assembly 68, which bears against a retaining nut 80 that secures the piston body 60 and bleed valve assemblies 64 and 68 to the piston rod 34.

[0023] The main pressure valve assembly 62 includes a support disc 84, a flexing preload disc 86, a plurality of valve discs 88, an interface disc 90, an interface 92, and an inlet valve disc 94. The support disc 84 is threaded or slid onto the piston rod 34 and is disposed over the piston body 60. The support disc 84 is positioned on the piston rod 34 so that the specific amount of preload is provided by the valve discs 88 and the interface disc 90, and is then welded to the piston rod 34 or secured to the piston rod 34 by other means known in the art. The interface 92 and inlet valve disc 94 can move freely axially with respect to the piston rod 34 to open and close the main pressure fluid passages 70 while the main pull fluid passages 72 and the discharge fluid passage 74 remain open.The axial movement of the interface 92 and inlet valve disc 94 eliminates the need for these components to flex to open the main pressure fluid passages 70, thus providing a fully offset valve disc for the assembly.

[0024] The relief pressure valve assembly 64 includes a bore disc 96, one or more first rotary discs 98, a closure disc 100, and one or more shims 102. The bore disc 96 directly engages the shoulder formed on the piston rod 34, and the bore disc 96 defines a first plurality of holes 104 and a second plurality of holes 106. The cross sections in Fig. 3 and Fig. 5a are taken through one of the plurality of holes 104 and one of the plurality of holes 106. As in Fig. 6A and Fig. 6B, the bore plate 96 may be replaced by a bore plate 96' where the plurality of holes 106 have been replaced by a plurality of holes or notches 106'.

[0025] The rotary discs 98 are arranged directly next to the bore disc 96, the closure disc 100 is arranged directly next to the rotary discs 98 and the shims 102 are arranged directly between the closure disc 100 and the piston body 60. As in Fig. 5A, the closure disc 100 is normally spaced from the bore disc 96 so that fluid can flow through the holes 104. During a compression stroke, the closure disc 100 deforms upwardly, as shown in Fig. 5A, and comes into contact with the bore plate 96 between holes 104 and 106 to close the holes 104.

[0026] Holes 104 and 106 define separate flow paths through bore disc 96. Holes 106 define a flow path that is always open, and holes 104 define a flow path that is normally open, but the flow path through holes 104 is closed by closure disc 100 during a compression stroke of piston assembly 32.

[0027] The main pull valve assembly 66 includes a support disc 114, a flexing preload disc 116, a plurality of valve discs 118, an interface disc 120, an interface 122, and an intake valve disc 124. The support disc 114 is threaded or slid onto the retaining nut 80 and is disposed beneath the piston body 60. The support disc 114 is positioned on the retaining nut 80 such that the specific amount of preload is provided by the valve discs 118 and the interface disc 120, and is then threaded onto the retaining nut 80 or secured to the retaining nut 80 by other means known in the art. The interface 122 and the inlet valve disc 124 can move freely axially with respect to the piston rod 34 to open and close the main pull fluid passages 72 while the main pressure fluid passages 70 and the discharge fluid passage 74 remain open.The axial movement of the interface 122 and the inlet valve disc 124 eliminates the need for these components to flex to open the main draft fluid passages 72, thus providing a fully offset valve disc for the assembly.

[0028] The drain pull valve assembly 68 includes a bore disc 96, one or more rotary discs 98, a closure disc 100, and one or more shims 102. The bore disc 96 directly engages the retaining nut 80, and the bore disc 96 defines the first plurality of holes 104 and the second plurality of holes 106. The cross sections in Fig. 3 and Fig. 5B are taken through one of the plurality of holes 104 and one of the plurality of holes 106. As in Fig. 6A and Fig. 6B, the bore plate 96 may be replaced by the bore plate 96', where the plurality of holes 106 have been replaced by the plurality of holes or notches 106'.

[0029] The rotary discs 98 are arranged directly next to the bore disc 96, the closure disc 100 is arranged directly next to the rotary discs 98 and the shims 102 are arranged directly between the closure disc 100 and the piston body 60. As in Fig. 5B, the closure disc 100 is normally spaced from the bore disc 96 so that fluid can flow through holes 104. During a pull stroke, the closure disc 100 deforms downward, as shown in Fig. 5B to contact the bore disc 96 between the holes 104 and 106 to close the holes 104.

[0030] Holes 104 and 106 define separate flow paths through bore disc 96. Holes 106 define a flow path that is always open, and holes 104 define a flow path that is normally open, but the flow path through holes 104 is closed by closure disc 100 during a retraction stroke of piston assembly 32.

[0031] During a compression stroke, three fluid flows exist between the lower working chamber 46 and the upper working chamber 44. A compression stroke of the piston assembly 32 causes the fluid pressure in the lower working chamber 46, in the plurality of main pressure fluid passages 70, and in the plurality of bleed fluid passages 74 to increase. Initially, fluid flows into the vent fluid passages 74, through holes 104 and 106 in the bore disc 96 of the vent pull valve assembly 68, through the vent fluid passages 74, through holes 104 and 106 in the bore disc 96 of the vent pressure valve assembly 64, and into the upper working chamber 44. The initial fluid flow is through a continuously open fluid flow path through holes 106 in the bore disc 96 of the vent pressure valve assembly 64, which allows fluid flow at zero or near-zero piston assembly 32 velocity during a compression stroke.In addition, a second fluid flow occurs through the holes 104 in the bore disc 96 of the relief pressure valve assembly 64. This allows the offset damping force to be eliminated at zero speed.

[0032] As the speed of the piston assembly 32 increases, the fluid pressure in the plurality of bleed fluid passages 74 increases and the fluid pressure force exerted on the closure disc 100 deforms the closure disc 100 upward, as shown in Fig. 5A to close the plurality of holes 104 in the bore disc 96 of the bleed pressure valve assembly 64 to block the second fluid flow and allow only fluid flow through the holes 106 in the bore disc 96 of the bleed pressure valve assembly 64.

[0033] As the speed of the piston assembly 32 continues to increase, the fluid pressure in the plurality of main pressure fluid passages 70 increases and the fluid pressure force exerted on the inlet valve disc 94 overcomes the biasing load of the valve discs 88 and the interface disc 90 and the inlet valve disc 94 moves axially to open the plurality of main pressure fluid passages 70 to provide the third fluid flow.

[0034] During a retraction stroke, three fluid flows also exist between the upper working chamber 44 and the lower working chamber 46. A retraction stroke of the piston assembly 32 causes the fluid pressure in the upper working chamber 44 to gradually increase in the plurality of main retraction fluid passages 72 and in the plurality of bleed fluid passages 74. Fluid flows into the vent fluid passages 74, through holes 104 and 106 in the bore disc 96 of the vent pressure valve assembly 64, through vent fluid passages 74, through holes 104 and 106 in the bore disc 96 of the vent pull valve assembly 68, and into the lower working chamber 46. The first fluid flow is through a continuously open fluid flow path through holes 106 in the bore disc 96 of the vent pull valve assembly 68, allowing fluid flow at zero or near-zero piston assembly 32 velocity during a pull stroke.Additionally, a second fluid flow occurs through holes 104 in the bore disc 96 of the bleed valve assembly 68. This allows for elimination of the offset damping force at zero speed.

[0035] As the speed of the piston assembly 32 increases, the fluid pressure in the plurality of bleed fluid passages 74 increases and the fluid pressure force exerted on the closure disc 100 deforms the closure disc 100 downward, as shown in Fig. 5B to close the plurality of holes 104 in the bore disc 96 of the vent pull valve assembly 68 to block the second fluid flow and only allow fluid flow through the holes 106 in the bore disc 96 of the vent pull valve assembly 68.

[0036] As the speed of the piston assembly 32 continues to increase, the fluid pressure in the plurality of main pull fluid passages 72 increases and the fluid pressure force exerted on the inlet valve disc 124 overcomes the biasing load of the valve discs 118 and the interface disc 120 and the inlet valve disc 124 moves axially around the plurality of main pull fluid passages 72 to provide the third fluid flow.

[0037] The main fluid flow pattern can be controlled by controlling the size and number of passages 70 and 72, the design of valve discs 88 and 118, and interface discs 90 and 120, as well as other design features for shock absorber 26. The bleed fluid flow pattern can be controlled by controlling the size and number of bleed fluid passages 74, the size and number of holes 104 and 106, and by controlling the thickness of rotary discs 98 and closure disc 100. This controls the piston speed at which the second flow path is closed by holes 104.

[0038] With reference now to Fig. 7 and Fig. 8, a locking disc assembly 200 is disclosed. The locking disc assembly 200 is a direct replacement for the locking disc 100. The locking disc assembly 200 includes a centering disc 202 and a locking disc 204. The centering disc 202 is disposed within an opening 206 defined by the locking disc 204. The thickness of the centering disc 202 is equal to or greater than the thickness of the locking disc 204, allowing axial movement of the locking disc 204 between the rotating discs 98 and the shims 102. The outer diameter of the centering disc 202 is slightly smaller than the outer diameter of the rotating discs 98 and the shims 102. Typically, the outer diameter of the centering disc 202 is 0.5 mm smaller than the outer diameter of the rotating discs 98 and shims 102, which have the same outer diameter. This configuration increases the flexibility of the locking disc assembly 200.

[0039] During a compression stroke, three fluid flows exist between the lower working chamber 46 and the upper working chamber 44. A compression stroke of the piston assembly 32 causes the fluid pressure in the lower working chamber 46, in the plurality of main pressure fluid passages 70, and in the plurality of bleed fluid passages 74 to increase. Fluid flows into the vent fluid passages 74, through the holes 104 and 106 in the bore disc 96 of the vent pull valve assembly 68, through the vent fluid passages 74, through the holes 104 and 106 in the bore disc 96 of the vent pressure valve assembly 64, and into the upper working chamber 44. The first fluid flow passes through a continuously open fluid flow path through the holes 106 in the bore disc 96 of the vent pressure valve assembly 64, allowing fluid flow at zero or near-zero piston assembly 32 velocity during a compression stroke.Additionally, a second fluid flow passes through the holes 104 in the bore disc 96 of the relief pressure valve assembly 64. This allows for elimination of the offset damping force at zero speed.

[0040] As the speed of the piston assembly 32 increases, the fluid pressure in the plurality of bleed fluid passages 74 increases and the fluid pressure force exerted on the closure disc assembly 200 deforms the closure disc 204 upward, as shown in Fig. 7 to close the plurality of holes 104 in the bore disc 96 of the bleed pressure valve assembly 64 to block the second fluid flow and only allow fluid flow through holes 106 in the bore disc 96 of the bleed pressure valve assembly 64.

[0041] As the speed of the piston assembly 32 continues to increase, the fluid pressure in the plurality of main pressure fluid passages 70 increases and the fluid pressure force exerted on the inlet valve disc 94 overcomes the biasing load of the valve discs 88 and the interface disc 90 and the inlet valve disc 94 moves axially to open the plurality of main pressure fluid passages 70 to provide the third fluid flow.

[0042] During a retraction stroke, three fluid flows also exist between the upper working chamber 44 and the lower working chamber 46. A retraction stroke of the piston assembly 32 causes the fluid pressure in the upper working chamber 44, in the plurality of main retraction fluid passages 72, and in the plurality of bleed fluid passages 74 to increase. Initially, fluid flow flows into the vent fluid passages 74, through the holes 104 and 106 in the bore disc 96 of the vent pressure valve assembly 64, through the vent fluid passages 74, through the holes 104 and 106 in the bore disc 96 of the vent pull valve assembly 68, and into the lower working chamber 46. The first fluid flow passes through a continuously open fluid flow path through the holes 106 in the bore disc 96 of the vent pull valve assembly 68, which allows fluid flow at a zero or near-zero speed of the piston assembly 32 during a pull stroke.Additionally, a second fluid stream passes through the holes 104 in the bore disc 96 of the bleed valve assembly 68. This allows for elimination of the offset damping force at zero speed.

[0043] As the speed of the piston assembly 32 increases, the fluid pressure in the plurality of bleed fluid passages 74 increases and the fluid pressure force exerted on the closure disc assembly 200 deflects the closure disc 204 downward, as shown in Fig. 5B to close the plurality of holes 104 in the bore disc 96 of the vent pull valve assembly 68 to block the second fluid flow and only allow fluid flow through the holes 106 in the bore disc 96 of the vent pull valve assembly 68.

[0044] As the speed of the piston assembly 32 continues to increase, the fluid pressure in the plurality of main pull fluid passages 72 increases and the fluid pressure force exerted on the inlet valve disc 124 overcomes the biasing load of the valve discs 118 and the interface disc 120 and the inlet valve disc 124 moves axially to open the plurality of main pull fluid passages 72 to provide the third fluid flow.

[0045] With reference now to Fig. 9 and 10A-10D, a piston assembly 232 includes the piston body 60, the main pressure valve assembly 62, a bleed pressure valve assembly 264, a main pull valve assembly 66, and a bleed pull valve assembly 268. The piston body 60 is attached to the piston rod 34 and defines the plurality of main pressure fluid passages 70, the plurality of main pull fluid passages 72, and the plurality of bleed fluid passages 74. The piston body 60 rests against the shoulder formed on the piston rod 34 and the retaining nut 80.

[0046] The main pressure valve assembly 62 includes a support disc 84, a flexing preload disc 86, the plurality of valve discs 88, the interface disc 90, the interface 92, and the intake valve disc 94. The support disc 84 is threaded or slid onto the piston rod 34 and is disposed over the piston body 60. The support disc 84 is positioned on the piston rod 34 so that the specific amount of preload is provided by the valve discs 88 and the interface disc 90, and is then welded to the piston rod 34 or secured to the piston rod 34 by other means known in the art. The interface 92 and the inlet valve disc 94 are free to move axially with respect to the piston rod 34 to open and close the main pressure fluid passages 70 while the main pull fluid passages 72 and the bleed fluid passage 74 remain open.The axial movement of the interface 92 and inlet valve disc 94 eliminates the need for these components to flex to open the main pressure fluid passages 70, thus providing a fully offset valve disc for the assembly.

[0047] The relief pressure valve assembly 264 includes a bore disc 96, a rotary disc 98, a closure disc 100, and a wave spring 302 or any other biasing element known in the art. The bore disc 96 directly engages the piston body 60, and the bore disc 96 defines a first plurality of holes or slots 104.

[0048] The rotary disc 98 is disposed directly adjacent to the bore disc 96, the closure disc 100 is disposed directly adjacent to the rotary disc 98, and the wave spring 302 is disposed directly between the closure disc 100 and the inlet valve disc 124 of the main pull valve assembly 66. The bore disc 96, the rotary disc 98, and the closure disc 100 can slide axially on the retaining nut 80 due to deflection of the wave spring 302. As shown in Fig. 10A, the closure disc 100 is normally spaced from the bore disc 96 so that fluid can flow through slots 104, as in Fig. 10A. Fluid flows both axially through slots 104 and radially through slots 104. During a compression stroke, the closure disc 100 bends upwards, as shown in Fig. 10B to contact the bore disk 96 to prevent axial flow through the slots 104 while allowing radial flow through the slots 104.

[0049] The slots 104 define two flow paths through the bore disc 96. The radial flow path defines a flow path that is always open and the axial flow path defines a flow path that is closed by the closure disc 100 during a compression stroke of the piston assembly 32.

[0050] The main pull valve assembly 66 includes a support disc 114, a flexing preload disc 116, the plurality of valve discs 118, the interface disc 120, the interface 122, and the intake valve disc 124. The support disc 114 is threaded or slid onto the retaining nut 80 and is disposed below the piston body 60. The support disc 114 is positioned on the retaining nut 80 so that the specific amount of preload is provided by the valve discs 118 and the interface disc 120, and is then welded to the retaining nut 80 or secured to the retaining nut 80 by other means known in the art. The interface 122 and the inlet valve disc 124 are free to move axially with respect to the piston rod 34 to open and close the main pull fluid passages 72 while the main pressure fluid passages 70 and the discharge fluid passage 74 remain open.The axial movement of the interface 122 and the inlet valve disc 124 eliminates the need for these components to flex to open the main draft fluid passages 72, thus providing a fully offset valve disc for the assembly.

[0051] The bleed valve assembly 268 includes the bore disc 96, the rotary disc 98, the closure disc 100, and a wave spring 302 or any other biasing element known in the art. The bore disc 96 directly engages the piston body 60, and the bore disc 96 defines the first plurality of slots 104. The cross sections in Fig. 9 and Fig. 10B are taken through one of the plurality of slots 104.

[0052] The rotary disc 98 is arranged directly next to the bore disc 96, the closure disc 100 is arranged directly next to the rotary disc 98, and the wave spring 302 is arranged directly between the closure disc 100 and the inlet valve disc 94 of the main pressure valve assembly 62. The bore disc 96, the rotary disc 98, and the closure disc 100 can slide axially on the retaining nut 80 due to the deflection of the wave spring 302. As shown in Fig. 10C, the closure disc 100 is normally positioned from the bore disc 96 so that fluid can flow through slots 104, as in Fig. 10C. Fluid flows both axially through the slots 104 and radially through the slots 104. During a pulling stroke, the closure disc 100 deforms downwards, as shown in Fig. 10D to engage the bore disk 96 to prevent axial flow through the slots 104 while allowing radial flow through the slots 104.

[0053] The slots 104 define two flow paths through the bore disc 96. The radial flow defines a flow path that is always open and the axial flow defines a flow path that is closed by the closure disc 100 during a retraction stroke of the piston assembly 32.

[0054] During a compression stroke, three fluid flows exist between the lower working chamber 46 and the upper working chamber 44. A compression stroke of the piston assembly 32 causes the fluid pressure in the lower working chamber 46 and in the plurality of main pressure fluid passages 70 to increase. Initially, fluid flows into the vent fluid passages 74, through the slots 104 in the bore disc 96 of the vent pressure valve assembly 264 in both axial and radial directions, through the vent fluid passages 74, and into the upper working chamber 44. As shown in Fig. As shown in Figure 10A, the first fluid flow passes through a continuously open radial fluid flow path through the slots 104 in the bore disc 96 of the bleed pressure valve assembly 264, allowing fluid flow at a zero or near-zero speed of the piston assembly 32 during a compression stroke. Additionally, a second fluid flow passes axially through the slots 104 in the bore disc 96 of the bleed pressure valve assembly 264. This allows for the elimination of the offset damping force at zero speed.

[0055] As the speed of the piston assembly 32 increases, the fluid pressure in the lower working chamber 46 increases and the fluid pressure force exerted on the closure disc 100 elastically deforms the closure disc 100 upward, as shown in Fig. 10B to close the axial flow through the slots 104 in the bore disc 96 of the bleed pressure valve assembly 264 to block the second fluid flow and allow only fluid flow radially through the slots 104 in the bore disc 96 of the bleed pressure valve assembly 264.

[0056] As the speed of the piston assembly 32 continues to increase, the fluid pressure in the plurality of main pressure fluid passages 70 increases and the fluid pressure force exerted on the inlet valve disc 94 overcomes the biasing load of the valve discs 88 and interface disc 90 and the inlet valve disc 94 moves axially to open the plurality of main pressure fluid passages 70 to provide the third fluid flow.

[0057] During a pull stroke, three fluid flows are also present between the upper working chamber 44 and the lower working chamber 46. A pull stroke of the piston assembly 32 causes the fluid pressure in the upper working chamber 44 and in the plurality of main pull fluid passages 72 to increase. Initially, fluid flows into the bleed fluid passages 74 through slots 104 in the bore disc 96 of the bleed pull valve assembly 268 in both axial and radial directions, through the bleed fluid passages 74 and into the lower working chamber 46. As in Fig. As shown in Figure 10C, the first fluid flow passes through a continuously open radial fluid flow path through the slots 104 in the bore disc 96 of the bleed pull valve assembly 268, allowing fluid flow at a zero or near-zero speed of the piston assembly 32 during a rebound stroke. Additionally, a second fluid flow passes axially through the slots 104 in the bore disc 96 of the bleed pull valve assembly 268. This allows for the elimination of the offset damping force at zero speed.

[0058] As the speed of the piston assembly 32 increases, the fluid pressure in the upper working chamber 44 increases and the fluid pressure force exerted on the closure disc 100 elastically deforms the closure disc 100 downward, as shown in Fig.10D to prevent axial flow through the slots 104 in the bore disc 96 of the vent pull valve assembly 68 to block the second fluid flow and allow only fluid flow radially through the slots 104 in the bore disc 96 of the vent pull valve assembly 68.

[0059] As the speed of the piston assembly 32 continues to increase, the fluid pressure in the plurality of main pull fluid passages 72 increases and the fluid pressure force exerted on the inlet valve disc 124 overcomes the biasing load of the valve discs 118 and the interface disc 120 and the inlet valve disc 124 moves axially to open the plurality of main pull fluid passages 72 to provide the third fluid flow.

[0060] The main fluid flow tuning can be controlled by controlling the size and number of passages 70 and 72, the design of valve discs 88 and 118, and interface discs 90 and 120, as well as other design features for shock absorber 26. The bleed fluid flow tuning can be controlled by controlling the size and number of bleed fluid passages 74, the size and number of slots 104, and by controlling the thickness of rotary disc 98 and closure disc 100. This controls the piston speed at which the second flow path is axially closed by slots 104.

Claims

[1] Shock absorber (26), comprising: a pressure tube (30) defining a fluid chamber (42); a piston assembly (32) disposed in the fluid chamber (42), the piston assembly (32) dividing the fluid chamber (42) into an upper working chamber (44) and a lower working chamber (46); a main pressure fluid passage (70) extending through the piston assembly (32) between the upper and lower working chambers (44, 46); a main pressure valve assembly (62) engaged with the piston assembly (32), the main pressure valve assembly (62) closing the main pressure fluid passage (70); a main traction fluid passage (72) extending through the piston assembly (32) between the upper and lower working chambers (44, 46); a main pull valve assembly (66) engaged with the piston assembly (32), the main pull valve assembly (66) closing the main pull fluid passage (72); a bleed fluid passage (74) extending through the piston assembly (32) between the upper and lower working chambers (44, 46); a bleed valve assembly (64, 68) engaged with the piston assembly (32) and operable to restrict fluid flow through the bleed fluid passage (74), the bleed valve assembly (64, 68) including a bore disc (96), a closure disc (100), and a rotary disc (98) disposed between the bore disc (96) and the closure disc (100), the closure disc (100) being axially slidable relative to the bore disc (96), the rotary disc (98), and the piston assembly (32), and resiliently deformable relative to the piston assembly (32), and the bore disc (96) including a plurality of holes (104, 106) or a plurality of notches (106') that at least partially define the bleed fluid passage (74) upon axial movement of the closure disc (100). [2] Shock absorber according to claim 1, wherein a thickness of the closure disc (100) is less than or equal to a thickness of the bore disc (96). [3] The shock absorber of claim 1, wherein the bleed valve assembly (64, 68) includes a spring disposed between the closure disc (100) and the main pressure valve assembly (62). [4] Shock absorber according to claim 3, wherein the closure disc (100) is axially slidable due to a deformation of the spring. [5] The shock absorber of claim 1, wherein the bleed valve assembly (64, 68) includes a spring disposed between the closure disc (100) and the main pull valve assembly (66). [6] Shock absorber according to claim 5, wherein the closure disc (100) is axially slidable due to a deformation of the spring. [7] The shock absorber of claim 1, wherein the closure disc (100) restricts flow through the vent fluid passage (74) when the closure disc (100) is in a deformed position. [8] Shock absorber according to claim 1, wherein the bore disc (96) is directly engaged with the piston assembly (32). [9] Shock absorber according to claim 1, wherein the rotary disc (98) is arranged immediately adjacent to the bore disc (96) and the closure disc (100).

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