Frequency-dependent damper

Abstract

Damping system for a vehicle (10) comprising the following: a cylinder (30) with a hydraulic fluid enclosed therein; a piston (32) slidably fitted into the cylinder (30), which divides the cylinder (30) into a first working chamber (44) and a second working chamber (46); a piston rod (34) which is connected to the piston (32) and extends from the cylinder (30); a disc valve assembly (62, 64) attached to the piston (32), wherein the disc valve assembly (62, 64) controls a fluid flow between the first working chamber (44) and the second working chamber (46); and an actuator (66) which is coupled to the piston rod (34) for movement, wherein the actuator (66) comprises a movable sleeve (102) and a collecting chamber (130) which is fluid-connected to the first working chamber (44) or the second working chamber (46), wherein the collecting chamber (130) comprises a flexible wall (106) which is composed of a stack of disks, wherein an increased pressure in the collecting chamber (130) generates a force on the flexible wall (106) to increase the volume of the collecting chamber (130) and a force on the movable sleeve (102) which acts on the disk valve arrangement (62, 64) to increase the resistance to opening the disk valve arrangement (62, 64).

Description

AREA

[0001] The present disclosure relates to motor vehicle shock absorbers. In particular, the present disclosure relates to internal structures of a passive shock absorber which is operable to provide different damping strengths based on a frequency and a velocity of the input into the shock absorber.

[0002] A damper system for frequency-dependent control is already known, for example, from DE 10 2015 205 556 A1. BACKGROUND

[0003] The statements in this section merely provide background information to the present disclosure and may not represent the state of the art.

[0004] Shock absorbers are typically used in conjunction with vehicle suspension systems or other suspension systems to absorb unwanted vibrations that occur during the movement of the suspension system. To absorb these unwanted vibrations, vehicle shock absorbers are generally connected between the sprung mass (body) and the unsprung mass (suspension / chassis) of the vehicle.

[0005] The most common type of shock absorber for motor vehicles can be either a single-tube or twin-tube dashpot design. In the single-tube design, a piston is located in a fluid chamber defined by a pressure tube and is connected to the vehicle's sprung mass via a piston rod. The pressure tube is connected to the vehicle's unsprung mass. The piston divides the pressure tube's fluid chamber into an upper working chamber and a lower working chamber. The piston incorporates a compression valve system that restricts the flow of damping fluid from the lower working chamber to the upper working chamber during a compression stroke, and a rebound valve system that restricts the flow of damping fluid from the upper working chamber to the lower working chamber during a rebound or extension stroke.Since the compression valve system and the rebound valve system can restrict the flow of damping fluid, the shock absorber can generate a damping force that counteracts the vibrations that would otherwise be transferred from the unsprung mass to the sprung mass.

[0006] In a twin-tube shock absorber, a fluid reservoir is defined between the pressure tube and a reservoir tube positioned around the pressure tube. A base valve assembly is located between the lower working chamber and the fluid reservoir to control the flow of damping fluid. The piston's compression valve system is relocated to the base valve assembly and replaced within the piston by a compression check valve assembly. In addition to the compression valve system, the base valve assembly includes a rebound check valve assembly. The compression valve system of the base valve assembly generates the damping force during a compression stroke, and the piston's rebound valve system generates the damping force during a rebound or extension stroke.Both the compression and rebound check valve arrangements allow fluid flow in one direction but prevent fluid flow in the opposite direction, and these valves can be designed to also generate a damping force.

[0007] The valve assemblies for the shock absorber also control the fluid flow between two chambers during the shock absorber's stroke. By controlling the fluid flow between the two chambers, a pressure drop is created between them, which contributes to the shock absorber's damping forces. The valve assemblies can be used to adjust the damping forces, thus improving ride comfort and handling, as well as controlling noise, vibration, and harshness.

[0008] Typical passive shock absorbers provide the same damping force regardless of the input frequency. For a given input velocity, the damping force produced by a conventional damper / shock absorber remains constant regardless of the input frequency. Typically, the primary driving frequency of a passenger car is in the range of 1-2 Hz. When a vehicle travels over a road surface with a low-frequency input, a higher damping force is preferred to manage the road inputs. A higher damping force is also preferred during driving behavior events (when directional stability is critical). A roll mode is a vehicle driving behavior control state. The roll mode of a typical passenger car might be in the range of 2-4 Hz, depending on the vehicle's roll stiffness and center of gravity height.Although there are semi-active damping shock absorbers that change the damping of the shock absorber in real time to take these vehicle inputs into account, there is a need for a passive shock absorber that can be operated in such a way as to provide frequency-dependent damping without complicated (active) controls. SUMMARY

[0009] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its complete scope of protection or all of its features.

[0010] According to the invention, a damping system with the features according to claim 1, a damping system with the features according to claim 7 and a damping system with the features according to claim 11 is proposed.

[0011] A damping system for a vehicle comprises a piston slidably fitted within a cylinder, dividing the cylinder into a first working chamber and a second working chamber. A piston rod is connected to the piston and extends from the cylinder. A disc valve assembly is attached to the piston and controls fluid flow between the first and second working chambers. An actuator is coupled to the piston rod and comprises a movable sleeve and a collection chamber that is fluidically connected to either the first or second working chamber. The collection chamber includes a flexible wall. Increased pressure in the collection chamber generates a force on the flexible wall, increasing the volume of the collection chamber, and a force on the movable sleeve, which acts on the disc valve assembly to increase the resistance to opening the main disc valve assembly.

[0012] The damper of the present disclosure operates by diverting the flow from the rebound chamber to apply pressure to the rear of a movable cylindrical sleeve. The movable cylindrical sleeve applies an additional load to the rebound stack and generates further resistance to the opening of the rebound-side main valve during a low-frequency event. During a high-frequency event, fluid entering the collection chamber deforms an expansion disk. During a high-frequency event, the flow reversal occurs much faster, and there is insufficient time to build up sufficient fluid pressure to preload the plunger. During compression, all damping at all input frequencies is provided by a main piston, and the devices of the present disclosure do not provide frequency-dependent damping in the compression operating mode.However, it is understood that the present disclosure considers the application of this technology to the compression side, the rebound side, or both.

[0013] Further areas of application are evident from the description provided here. It is understood that the description and specific examples serve only for illustration and are not intended to limit the scope of protection afforded by this disclosure. DRAWINGS

[0014] The drawings described here serve only to illustrate selected embodiments and not all possible implementations, and are not intended to limit the scope of protection of the present disclosure. Fig. Figure 1 is a representation of an exemplary vehicle equipped with a frequency-dependent damper according to the teachings of the present disclosure; Fig. Figure 2 is a fragmentary side view of a shock absorber constructed according to the teachings of the present disclosure; Fig. Figure 3 is a fragmentary cross-sectional view of a shock absorber constructed according to the teachings of the present disclosure; Fig. Figure 4 is a stretched perspective view of a check valve; Fig. Figure 5 is an expanded perspective view of a flexible wall of a collection chamber of an exemplary shock absorber; Fig. Figure 6 is a fragmentary cross-sectional view showing an adaptive damping force generation mechanism comprising a clamping disc check valve and a collecting chamber comprising a flexible wall; Fig. Figure 7 is a perspective view of a clamping disc check valve; Fig. Figure 8 is a fragmentary cross-sectional view of a shock absorber equipped with a separating piston; Fig. 9 is a fragmentary cross-sectional view of another shock absorber equipped with a separating piston and spring; Fig. Figure 10 is a graphical representation showing the peak rebound force as a function of the rebound frequency for a frequency-dependent damper and a passive damper; and Fig. Figure 11 is a graphical representation that provides test results for force as a function of shock displacement for a shock absorber constructed according to the teachings of the present disclosure.

[0015] Across the different views of the drawings, matching reference symbols indicate matching parts. DESCRIPTION

[0016] The following description is merely exemplary and is not intended to limit the present disclosure, application or uses.

[0017] Exemplary embodiments are provided so that this disclosure is thorough and fully conveys the scope of protection to the person skilled in the art. Numerous specific details are given, such as examples of specific components, devices, and methods, to provide a thorough understanding of the embodiments of this disclosure. It is obvious to the person skilled in the art that the specific details need not be used, that exemplary embodiments can be implemented in many different forms, and that none should be interpreted as limiting the scope of protection of the disclosure. In some exemplary embodiments, well-known methods, well-known device structures, and well-known technologies are not described in detail.

[0018] The terminology used here serves only to describe certain exemplary embodiments and should not be understood as a limitation. As used here, the singular forms "a," "an," and "the" are intended to possibly also include the plural forms, unless the context explicitly indicates otherwise. The expressions "comprises," "include," "contain," and "exhibit" are meant inclusively and therefore indicate the presence of the listed features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.The procedural steps, procedures, and processes described here should not be interpreted as requiring their execution in the specific order discussed or presented, unless explicitly stated as the order of execution. It is further understood that additional or alternative steps may be applied.

[0019] When an element or layer is described as "at," "interacting with," "connected with," or "coupled with" another element or layer, it may be directly adjacent to, interacting with, connected to, or coupled with that other element or layer, or there may be intervening elements or layers. Conversely, when an element is described as "directly adjacent to," "directly interacting with," "directly connected with," or "directly coupled with" another element or layer, there may be no intervening elements or layers. Any other wording used to describe the relationship between elements should be interpreted similarly (for example, "between" versus "directly between," "next to" versus "directly beside," etc.).As used here, the term “and / or” includes any and all combinations of one or more of the associated listed objects.

[0020] Although the terms first, second, third, etc., may be used here to describe various elements, components, areas, layers, and / or sections, these elements, components, areas, layers, and / or sections should not be restricted by these terms. These terms may only be used to distinguish one element, component, area, layer, or section from another. Terms such as "first," "second," and other numerical terms used here do not imply any sequence or order unless this is clear from the context.Thus, a first element, a first component, a first area, a first layer or a first section discussed below could be referred to as a second element, a second component, a second area, a second layer or a second section without deviating from the teachings of the exemplary embodiments.

[0021] Spatially related terms such as "inner," "outer," "below," "under," "lower," "above," "upper," and the like can be used here to simplify the description and describe the relationship of an element or feature to one or more other elements or features, as illustrated in the figures. The purpose of spatially related terms is to encompass various orientations of the device in use or operation, in addition to the orientation shown in the figures. For example, if the device in the figures is turned upside down, elements described as "below" or "underneath" other elements or features would then be oriented "above" them. Thus, the exemplary term "below" can encompass both an orientation above and one below.The device can also be oriented differently (rotated by 90 degrees or in other orientations), and the spatially related descriptive terms used here are interpreted accordingly.

[0022] With reference now made to the drawings, in which the same reference symbols across the different views indicate identical or corresponding parts, it is stated in Fig. Figure 1 shows a vehicle 10 comprising 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) designed to functionally support the rear wheels 18 of the vehicle. The rear axle assembly is operatively connected to the body 16 by a pair of shock absorbers 20 and a pair of coil springs 22. Similarly, the front suspension 14 comprises a transversely extending front axle assembly (not shown) for functionally supporting the front wheels 24 of the vehicle. The front axle assembly is operatively connected to the body 16 by a second pair of shock absorbers 26 and a pair of coil springs 28. The shock absorbers 20 and 26 serve to dampen the relative movement of the unsprung part (i.e. the front and rear wheel suspension 12 and 14 respectively) and the sprung part (i.e. the body 16) of the vehicle 10.Although vehicle 10 has been depicted as a passenger car with a front and a rear axle arrangement, the shock absorbers 20 and 26 can also be used with other types of vehicles or machines and / or in other applications, such as vehicles with independent front and / or independent rear suspension systems. Furthermore, the term "shock absorber," as used here, is intended to mean dampers in general and thus includes spring struts.

[0023] With reference to Fig. Section 2 shows the shock absorber 20 in more detail. Although Fig. Figure 2 shows only the shock absorber 20; it is understood that the shock absorber 26 also includes the piston assembly described below for the shock absorber 20. The shock absorber 26 differs from the shock absorber 20 only in the way it is designed to connect to the sprung and unsprung parts of the vehicle 10. The shock absorber 20 comprises a pressure tube 30, a piston assembly 32, and a piston rod 34.

[0024] The pressure tube 30 defines a working chamber 42. The piston assembly 32 is slidably arranged within the pressure tube 30 and divides the working chamber 42 into an upper working chamber 44 and a lower working chamber 46. A seal 48 is arranged between the piston assembly 32 and the pressure tube 30 to allow sliding movement of the piston assembly 32 relative to the pressure tube 30 without generating excessive frictional forces and to seal 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, which closes the upper end of the pressure tube 30. A sealing system 52 seals the interface between the upper end cap 50 and the piston rod 34. The end of the piston rod 34 opposite the piston arrangement 32 is designed to be secured to the sprung part of the vehicle 10.In the preferred embodiment, the piston rod 34 is secured to the vehicle body 16 or the sprung part of the vehicle 10. The pressure tube 30 is filled with fluid and includes a connecting part 54 for attachment to the other mass of the vehicle—either the sprung or the unsprung mass. In the preferred embodiment, the connecting part 54 is secured to the unsprung mass of the vehicle. Thus, suspension movements of the vehicle cause extension or compression movements of the piston assembly 32 relative to the pressure tube 30. A valve system in the piston assembly 32 controls the fluid movement between the upper working chamber 44 and the lower working chamber 46 during the movement of the piston assembly 32 in the pressure tube 30.

[0025] With reference to Fig. 3 and Fig. 4 A piston assembly 32 is attached to the piston rod 34 and comprises a piston body 60, a compression valve assembly 62, an expansion or rebound valve assembly 64, and a mechanism 66 for adaptive damping force generation. The piston rod 34 includes a reduced-diameter section 68 positioned at the end of the piston rod 34 located in the pressure tube 30, forming a shoulder 70 for attaching the remaining components of the piston assembly 32. The piston body 60 is positioned at the reduced-diameter section 68, with the compression valve assembly 62 positioned between the piston body 60 and the shoulder 70, and the rebound valve assembly 64 positioned between the piston body 60 and a threaded end 72 of the piston rod 34. The piston body 60 defines multiple compression flow channels 74 and multiple rebound flow channels 76.

[0026] The compression valve assembly 62 comprises several compression valve plates 78 and a valve stop 80. The valve plates 78 are arranged adjacent to the piston body 60 to cover the several compression flow channels 74. The valve stop 80 is arranged between the valve plates 78 and the shoulder 70 to limit the deformation of the valve plates 78. During a compression stroke of the shock absorber 20, fluid pressure builds up in the lower working chamber 46 until the fluid pressure applied to the valve plates 78 through the channels 74 overcomes the load required to deform the valve plates 78. The valve plates 78 deform elastically to open the channels 74 and allow fluid to flow from the lower working chamber 46 to the upper working chamber 44, as indicated by the arrows 82 in the figure. Fig. 3 is shown.

[0027] The rebound valve assembly 64 comprises several valve plates 86. The valve plates 86 are arranged adjacent to the piston body 60 to cover the multiple rebound flow channels 76. The adaptive damping force generation mechanism 66 is screwed onto one end 72 of the piston rod 34 to hold the valve plates 86 against the piston body 60 and close the channels 76. During an extension stroke of the shock absorber 20, fluid pressure builds up in the upper working chamber 44 until the fluid pressure applied to the valve plates 86 through the channels 76 overcomes the load required to deform the valve plates 86. The valve plates 86 deform elastically, opening the channels 76 to allow fluid to flow from the upper working chamber 44 to the lower working chamber 46, as indicated by arrows 92 in the figure. Fig. 3 is shown.

[0028] Since the adaptive damping force generation mechanism 66 is fixed to the piston rod 34, the entire mechanism 66 moves translationally during the extension and compression of the piston rod 34. The adaptive damping force generation mechanism 66 is rigidly connected to the piston assembly 32 but does not act to provide a seal in the pressure tube 30 in which it is located. A frequency-dependent damper (FDD) is provided by a combination of components, including the adaptive damping force generation mechanism 66.

[0029] The mechanism 66 for adaptive damping force generation comprises a valve housing 100, a plunger or an axially translationally movable sleeve 102, a check valve 104, and a deformable wall 106. A flow channel 110 is in flow communication with the upper working chamber 44 and a stage chamber 112. The stage chamber 112 is partially defined by the valve housing 100 and the check valve 104. In particular, the check valve 104 comprises a cup-shaped retaining device 114, which is positioned in a recess 116 of the valve housing 100. The retaining device 114 is sealed to the valve housing 100. The retaining device 114 includes a recess 118 extending through it.A flexible check disc 120 and a flexible perforated disc 122 cover the recess 118, while a coil spring 124 biases the check disc 120 and the perforated disc 122 into a seated position engaging the holding device 114, as shown in . Fig. Figure 3 illustrates this. In the seated position, a flow connection between the stage chamber 112 and a collecting chamber 130 is provided solely via a slot 134 extending through the perforated disc 122. As described in detail, the perforated disc 122 and the check valve can be pressed from the seated position towards the piston rod 34 when the pressure in the collecting chamber 130 exceeds the pressure in the stage chamber 112.

[0030] The flexible wall 106 consists of a stack of discs as shown in Fig. 5 together. A support disc 140 is positioned closest to the collection chamber 130. A spacer disc 142 is arranged between the support disc 140 and an upper surface of an expansion disc 144. The expansion disc 144 is a continuous, uninterrupted element that seals against the valve housing 100 to prevent fluid from flowing from the collection chamber 130 into the lower working chamber 42. One or more additional spacer discs 148 are positioned between a lower surface of the expansion disc 144 and a restraint disc 150. The flexible wall 106 is held in a recess 160 of the valve housing 100. A number of conventional retaining devices can be used, such as... B. retaining rings, gluing, pressing, etc. The expansion washer 144, the spacer washers 142, 148 and the washers 140, 150 can be made of aluminum, steel, plastic, etc.Both the support disc 140 and the restraint disc 150 include several recesses 164 to allow fluid to flow through while maintaining the structural stiffness of each disc.

[0031] An axially translationally movable sleeve 102 is essentially a tubular element comprising a reduced-diameter section 170 and a larger-diameter section 172. The valve housing 100 comprises a similarly stepped structure with a reduced-diameter section 176, a larger-diameter section 178, and a medium-diameter section 180, which is positioned axially between the reduced-diameter section 176 and the larger-diameter section 178. A first seal 182 is positioned in a groove 184 of the valve housing 100. A second seal 186 is positioned in a second groove 188 of the valve housing 100. Based on the axial position of the first seal 182, the second seal 186, and the intermediate section 180, a tappet chamber 190 is provided. A radially extending recess 192 places the tappet chamber 190 in flow communication with the collecting chamber 130.When the tappet chamber 190 is pressurized, the sleeve 102 is pressed against the rebound valve assembly 64. The magnitude of the force exerted by the sleeve 102 is based on the pressure in the tappet chamber 190 and the effective area on an annular web 196 on the sleeve 102. It is understood that the effective area of ​​the web 196 can be varied relatively easily by changing the geometric relationship between the second seal 186 and the first seal 182.

[0032] In the embodiment that is in Fig. As shown in Figure 3, the sleeve 102 can be engaged with a support ring 200. The support ring 200 can move axially without hindrance with respect to the spring-loaded valve assembly 64. The support ring 200 comprises an engagement surface 202, which is positioned on an outer circumferential extension of the support ring 200. In the Fig. In the example shown in Figure 3, the support disc 200 supports the spring-loaded disc stack on an outer periphery. This ensures that a given ram force generates a maximum level of resistance to spring-loaded opening. The design of the sleeve 102 incorporates a smaller effective area of ​​the web 196, which in turn allows for a smaller outer diameter of the larger-diameter section 172, thus improving packaging. Furthermore, component optimization allows a single design to be applied to multiple bores, reducing manufacturing complexity. A manufacturer can achieve economies of scale for most of the additional components.

[0033] It is noted that the radial position of the engagement surface 202 can be varied to apply a force to different sections of the rebound valve assembly 64, thereby producing a different modification of the performance of the rebound valve assembly 64. To individually tailor suspension characteristics to a specific vehicle application, it may be desirable to modify the system response and operation of the rebound valve assembly 64 based on the vehicle type and configuration. By using a series of different support rings 200 with an engagement surface 202 positioned at different radial locations, a basic valve body 100 and a basic sleeve 102 can be used with all dampers. Another feature of the support ring 200 relates to the degree of freedom of its axial translational movement, which allows for venting of the rebound valve assembly 64.

[0034] To address potential concerns that an impact of the ring 200 on the rebound valve assembly 64 could cause NVH and / or pose a durability problem, the sleeve 102 can be spring-loaded towards the rebound valve assembly 64. A spring can be located at one end of the sleeve 102 or in the tappet chamber 190. It is further understood that the support ring 200 is optional. The sleeve 102 can engage directly with the rebound valve assembly 64 if the support ring 200 is not present.

[0035] Fig. Figure 3 shows the sleeve 102 in a retracted position, in which no force is applied to the rebound valve assembly 64. The axial movement of the sleeve 102 in one direction is limited by a stop surface 208. It is understood that the stop surface 208 need not be a complete, uninterrupted annular rib, but can also be defined by projections spaced apart from one another around the circumference or by other mechanical structures.

[0036] The operation of the shock absorber 20 varies based on the direction and frequency of input forces. A low-frequency rebound operating mode is now described. During the rebound stroke, fluid in the upper working chamber 44 is compressed, and fluid flows between the upper working chamber 44 and the lower working chamber 46 through the channels 76, overcoming the load required to deform the valve plates 86 of the rebound valve assembly 64, thus allowing fluid to flow as indicated by arrows 92. Fluid pressure in the upper working chamber 44 also flows through the channel 110 of the piston rod 34 and into the stage chamber 112. From the stage chamber 112, fluid flows through the slot 134 of the perforated disc 122 and enters the collecting chamber 130. As a result, the pressure in the collecting chamber 130 downstream of the perforated disc 122 is lower compared to the springback chamber pressure prevailing in the step chamber 112.

[0037] As the pressure in the collection chamber 130 increases, the expansion disc 144 begins to deform around the spacer disc 148. With a further increase in pressure, the deformation of the expansion disc 144 intensifies until it reaches a maximum when the expansion disc 144 contacts the restraint disc 150. The purpose of the restraint disc 150 is to provide support for the support disc 140 under high pressure. For the operation of the rebound valve assembly 64, it is essential that the expansion disc 144 maintains a seal between the collection chamber 130 and the lower working chamber 42. Without the restraint disc 150, the expansion disc 144 could "break through" under the very high pressures that occur during a rebound stroke.Spacer discs 148 are provided between the expansion disc 144 and the limiting disc 150 to provide a tuning feature for defining a path length in which the expansion disc 144 can deform before it touches the limiting disc 150.

[0038] As the pressure in the collection chamber 130 increases, fluid begins to flow through the channel 192 to pressurize the plunger chamber 190 and the bridge 196. The pressure on the bridge 196 causes the sleeve 102 to move translationally, applying a load to support the ring 200. The force exerted by the sleeve 102 and the support ring 200 is applied as an additional force to the valve plates 86 and generates increased resistance to the opening of the spring-loaded valve assembly 64 under low-frequency conditions. It is understood that a certain amount of time is required for fluid to flow from the stage chamber 112 to the collection chamber 130. The deformation of the flexible wall 106 also requires time. The time delay in the deformation of the expansion disk 144 and the provision of the controlled pressure build-up by the perforated disk 122 provides frequency-dependent damping.

[0039] During the rebound of the damper in a high-frequency input mode, fluid flows through the channel 110 of the piston rod 34 into the stage chamber 112. From there, fluid flows through the perforated disc 122 and enters the collection chamber 130. As a result, the pressure in the collection chamber 130 is lower than the pressure in the stage chamber 112. As the pressure in the collection chamber 130 increases, the expansion disc 144 begins to deform around the spacer disc 148. Due to the nature of the high-frequency input, a piston rod stroke reversal occurs before the fluid can build up pressure in the plunger chamber 190. This timing requirement and the flexibility of the collection chamber wall 106 ensure that no additional load is applied to the sleeve 102. The flexibility or expansion capacity of the collection chamber 130 can be adjusted by varying the stiffness of the expansion disc 144.In other words, the pressure in the piston chamber 190, which can cause movement of the sleeve 102, compared to the pressure in the collecting chamber 130, determines the degree of preload that the sleeve 102 generates. This, in turn, depends on the input frequency. At a higher frequency, pressure builds up in the collecting chamber 130 and energy is directed to the bending expansion disk 144, but there is not enough time available to charge the tappet chamber 190. At lower frequencies, the fluid pressure builds up in the tappet chamber 190 and acts on the web 196 of the sleeve 102.

[0040] It is noted that the fluid flow path through the piston assembly 32 along arrows 82 remains the same during a rebound stroke, whether at a high or low frequency. The only difference lies in the degree of preload on the valve plates 86 to limit the opening of the rebound valve assembly 64.

[0041] During compression or rebound of the shock absorber 20, the pressure in the upper working chamber 44 is lower than the pressure in the collecting chamber 130. Fluid flows from the collecting chamber 130 through the check valve 104. The operation of the check valve ensures that the collecting chamber 130 remains ready to build up pressure during the rapid reversal of the stroke. During the compression stroke, fluid in the lower working chamber 42 also presses against the expansion disc 144. The expansion disc 144 deforms and is supported by the support disc 140 as needed.

[0042] Several features of the shock absorber 20 can be varied to adjust operating characteristics during frequency-dependent damping. For example, the perforated disc 122 throttles the flow through the piston rod 34 to the collecting chamber 130. The hole size and / or number of openings in the perforated disc 122 are adjustable and result in different frequency-dependent damping. It is understood that the perforated disc 122 can be shaped as desired and need not be configured as a flexible cylindrical element with a diameter greater than its height. The perforated disc 122 can be described as a perforated wall that defines, at least in part, an expandable collecting chamber. The perforated wall separates the first working chamber from the collecting chamber and can be a rigid element.

[0043] The stiffness of the expansion disk 144 can be adjusted to allow a change in the volume of the collection chamber 130. The collection chamber 130 can be expanded based on a deformation of the expansion disk 144. The size of a recess 210 ( Fig. 5), which extends through the spacer disk 148, defines where the expansion disk 144 deforms.

[0044] The limiting washer 150 supports the expansion washer 144 and prevents its failure under high accumulated pressure. The spacer washers 148 define the distance the expansion washer 144 can travel before contacting the limiting washer 144. A surface of the web 196, upon which the pressurized fluid acts, generates a preload. Varying this surface area changes the force applied by the sleeve 102.

[0045] During rebound, the check disc 120 and the perforated disc 122 remain "seated" in the holding device 114 and fluid flows around the outer diameter of the check disc to the collecting chamber 130 through the slot 134 on the perforated disc 122.

[0046] During a damper compression stroke, the pressure in the upper working chamber 44, the channel 110, and the stage chamber 112 is lower than the pressure in the collecting chamber 130, thus allowing fluid to flow from high pressure to low pressure through the perforated disc slot 134. The fluid pushes the check disc 120 against the spring force, resulting in a pressure release in the collecting chamber 130. This allows pressure relief in the collecting chamber 130.

[0047] Fig. 6 and Fig. Figure 7 represents an alternative check valve to a clamp disc check valve 280. The use of a clamp disc design ensures efficient space utilization and offers a packaging advantage. The clamp disc check valve 280 comprises a support disc 284, a spacer disc 286, a check disc 288, and a support disc 290. All discs of the clamp disc check valve 280 are positioned side by side and clamped with a preload into the recess 116 of the valve body 100.

[0048] The check valve 288 comprises a movable flap 292, which is connected to an outer ring 294 via a hinge 296. The deflection of the flap 292 towards the collecting chamber 130 is limited by the support disk 290. During a damper rebound stroke, fluid flows through the recesses 295 of the support disk 284. Fluid also flows through a hole 298 in the center of the check valve 288.

[0049] The check valve 288 is constructed of an elastomer material, allowing the flap 292 to move relative to the outer ring 294 during a compression stroke. The spacer 286 includes a recess 299 that is larger than the recess 301 of the support disc 290. During a compression stroke, the cap 292 is biased into the recess 299 to allow fluid to flow from the collecting chamber 130 through the clamping disc check valve 280 and into the stage chamber 112.

[0050] In Fig. Figure 8 shows a damper or shock absorber 300 of an alternative embodiment. The shock absorber 300 is essentially similar to the shock absorber 20, with the main difference being that the flexible wall 106 is replaced by a separating piston 304. Thus, a member that is movable to allow an increase in the volume of the collecting chamber can comprise the expansion disk 144 or the piston 304. The piston 304 is slidably positioned in a bore 306. A seal 308 prevents fluid from flowing from a collecting chamber 310 into the lower working chamber 46. The possible stroke length for the separating piston 304 can be varied based on the placement of a stop 312 formed on a valve housing 314 and the relative position of an end plate 318 fixed to the housing 314.By varying the position of these components, the maximum volume of the collection chamber 310 is maintained to effect a low-frequency delay.

[0051] Fig. Figure 9 shows a variant of the shock absorber 300, designated as a shock absorber 300'. The shock absorber 300' is essentially similar to the shock absorber 300, but additionally features a spring 320 that presses the separating piston 304 against a check valve 322. The spring 320 assists in the fluid transport from the collection chamber 310 during a compression stroke when the fluid pressure in the upper working chamber 44 is less than the pressure in the collection chamber 310. The preload and spring rate of the spring 320 further define the performance characteristics of the frequency-dependent damping provided by the shock absorber 300' during operation in the low-frequency rebound mode. A spring 320 with a relatively high rate would load the collection chamber 310 in a shorter time than a damper equipped with a spring 320 with a lower rate.

[0052] Other variants include positioning an additional spring opposite the separating piston 304 to position the separating piston 304 at a suitable location in the bore 306, while adjusting the operating characteristics of the frequency-dependent damper, as previously discussed. A further alternative embodiment involves positioning the preload spring only on the side of the separating piston 304 as a check valve 322 and omitting the spring 320.

[0053] Fig. 10 and Fig. Figure 11 shows typical output results, comparing reaction characteristics between a shock absorber equipped with a typical passive valve and a shock absorber equipped with the frequency-dependent damping mechanism comprising the previously discussed actuator, which can be operated to increase the resistance to fluid flow through the rebound valve arrangement 64. Fig. 10 represents a reduction in the peak rebound force provided by the shock absorber 20 with an increase in the rebound frequency. Fig. Figure 11 presents the test results for a shock absorber constructed according to the teachings of the present disclosure, comparing force as a function of shock displacement. A negative force indicates rebound, and a positive force is generated during compression. Frequency dependence can be visually observed by the varying peak force in the rebound direction. The test was performed by displacing the shock absorber at a constant velocity.

[0054] The foregoing description of embodiments is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular embodiment are generally not restricted to that particular embodiment, but, where applicable, are interchangeable and may be used in a selected embodiment, even if not specifically shown or described. This embodiment may also be modified in various ways. Such variations shall not be considered a departure from the present disclosure, and all such modifications shall be included within the scope of protection of the present disclosure.

Claims

[1] Damping system for a vehicle (10) comprising the following: a cylinder (30) with a hydraulic fluid enclosed therein; a piston (32) slidably fitted into the cylinder (30), which divides the cylinder (30) into a first working chamber (44) and a second working chamber (46); a piston rod (34) which is connected to the piston (32) and extends from the cylinder (30); a disc valve assembly (62, 64) attached to the piston (32), wherein the disc valve assembly (62, 64) controls a fluid flow between the first working chamber (44) and the second working chamber (46); and an actuator (66) which is coupled to the piston rod (34) for movement, wherein the actuator (66) comprises a movable sleeve (102) and a collecting chamber (130) which is fluid-connected to the first working chamber (44) or the second working chamber (46), wherein the collecting chamber (130) comprises a flexible wall (106) which is composed of a stack of disks, wherein an increased pressure in the collecting chamber (130) generates a force on the flexible wall (106) to increase the volume of the collecting chamber (130) and a force on the movable sleeve (102) which acts on the disk valve arrangement (62, 64) to increase the resistance to opening the disk valve arrangement (62, 64). [2] Damper system according to claim 1, further comprising a movable perforated plate (122) which is fixed to move with the piston rod (34) and is positioned between the first working chamber (44) or the second working chamber (46) and the collecting chamber (130), wherein the movement of the perforated plate is restricted, causing the hole (134) to restrict a fluid flow into the collecting chamber (130) when the pressure in the first working chamber (44) or the second working chamber (46) is higher than the pressure in the collecting chamber (130). [3] Damper system according to claim 2, wherein the perforated plate (122) moves to allow fluid to bypass the hole (134) when the pressure in the collecting chamber (130) is higher than the pressure in the first working chamber (44) or the second working chamber (46). [4] Damper system according to claim 2, wherein the perforated plate (122) is spring-loaded into a seated position, blocking movement of the perforated plate (122). [5] Damper system according to claim 1, wherein the actuator (66) comprises a housing (100) which defines at least part of the collecting chamber (130), wherein the sleeve (102) delimits the housing (100). [6] Damper system according to claim 5, wherein the sleeve (102) comprises a section (170) with a reduced diameter which is sealed to a section (176) with a reduced diameter of the housing (100). [7] Damping system for a vehicle (10) comprising the following: a cylinder (30) with a hydraulic fluid enclosed therein; a piston (32) slidably fitted into the cylinder (30), which divides the cylinder (30) into a first working chamber (44) and a second working chamber (46); a piston rod (34) which is connected to the piston (32) and extends from the cylinder (30); and a mechanism (66) for adaptive damping force generation which generates a variable damping force by controlling the flow of the hydraulic fluid induced by a sliding movement of the piston (32); and a disc valve (62, 64), with an upstream and a downstream side, which is attached to the piston (32), wherein the disc valve (62, 64) opens when a threshold pressure is reached between the first working chamber (44) and the second working chamber (46); wherein the mechanism (66) for adaptive damping force generation comprises the following: a housing (100) which is attached to the piston rod (34) and comprises a fixed base and a movable sleeve (102); a fluid chamber (112, 130, 190) in the housing (100), which is connected to the first working chamber (44) by a first communication passage (110) or the second working chamber (46) is connected to the flow; a link (144, 304) fixed in the housing (100), which serves as a first section of a wall of the fluid chamber (112, 130, 190), a second section of the wall of the fluid chamber (112, 130, 190) formed by a section of the movable sleeve (102); wherein the volume of the fluid chamber (112, 130, 190), under pressure, can increase by a movement of the link (144, 304) and the volume of the fluid chamber (112, 130, 190) can also increase by a movement of the sleeve (102), wherein the link (144, 304) moves upon high frequency input and the sleeve (102) moves upon low frequency input. [8] Damper system according to claim 7, wherein a first section (112, 130) of the fluid chamber (112, 130, 190) is positioned in the fixed base and a second section (190) of the fluid chamber (112, 130, 190) is positioned outside the fixed base. [9] Damper system according to claim 8, wherein the second section (190) of the fluid chamber (112, 130, 190) is positioned annularly around the first section (112, 130) of the fluid chamber (112, 130, 190). [10] Damper system according to claim 9, wherein the first section (112, 130) of the fluid chamber (112, 130, 190) and the second section (190) of the fluid chamber (112, 130, 190) are fluidically connected by a second communication passage (192) which extends through a wall of the housing (100). [11] Damping system for a vehicle (10) comprising the following: a cylinder (30) with a hydraulic fluid enclosed therein; a piston (32) slidably fitted into the cylinder (30), which divides the cylinder (30) into a first working chamber (44) and a second working chamber (46); a piston rod (34) which is connected to the piston (32) and extends from the cylinder (30); and a mechanism (66) for adaptive damping force generation which generates a variable damping force by controlling the flow of the hydraulic fluid induced by a sliding movement of the piston (32); and a disc valve (62, 64), with an upstream and a downstream side, which is attached to the piston (32), wherein the disc valve (62, 64) opens when a threshold pressure is reached between the first working chamber (44) and the second working chamber (46); wherein the mechanism (66) for adaptive damping force generation comprises the following: a housing (100) which is attached to the piston rod (34) and comprises a fixed base and a movable sleeve (102); a fluid chamber (112, 130, 190) in the housing (100), which is connected to the first working chamber (44) by a first communication passage (110) or the second working chamber (46) is connected to the flow; a link (144, 304) fixed in the housing (100), which serves as a first section of a wall of the fluid chamber (112, 130, 190), a second section of the wall of the fluid chamber (112, 130, 190) formed by a section of the movable sleeve (102); wherein the volume of the fluid chamber (112, 130, 190), under pressure, can increase by a movement of the link (144, 304) and the volume of the fluid chamber (112, 130, 190) can also increase by a movement of the sleeve (102), wherein the movable sleeve (102) comprises a section (170) with a first diameter, a section (172) with a second stepped diameter having a diameter larger than the section (170) with the first stepped diameter, and a transition area in between; wherein the difference between the first diameter of the sleeve (102) and the second stepped diameter of the sleeve (102) creates a section (190) of the fluid chamber (112, 130, 190) outside the fixed base and the volume of the section (190) of the fluid chamber (112, 130, 190) positioned outside the fixed base increases when the movable sleeve (102) is subjected to increasing pressure. [12] Damper system according to claim 11, further comprising a first O-ring (186) having a first diameter that seals a gap between the first sleeve diameter and the fixed base, and a second O-ring (182) having a second diameter that seals a gap between the second sleeve diameter and the fixed base, wherein the first O-ring (186) is larger than the second O-ring (182).

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