Not applicable.
The present general inventive concept relates to hydraulic shock absorbers, and, more particularly, to an improved damping valve stack in a hydraulic shock absorber.
Hydraulic shock absorbers dampen the release of energy stored in a compressed spring. Typically, a piston with orifices formed therein is forced through a reservoir of oil, and the resistance of the oil to flow through the orifices increases as the piston's velocity, or shaft velocity, through the oil increases. Shaft velocity is the result of vertical wheel speed during suspension movements. It is the relationship between shaft velocity and damping force that defines a shock absorber's performance (valving). Deflective disk valving was developed as a way to spring load the orifices of the piston, which increased damping forces at slow shaft velocities, and at the same time eliminated the excessive forces created by high-speed shaft movements. The result of such valving was a more linear response to shaft velocity, as opposed to the progressive (nearly exponential) response of the early technology. Another development was digressive valving, which is substantially the opposite of progressive, wherein the rate of increase of damping force begins to digress, relative to shaft velocity, past a certain point of the shaft velocity. Shocks can have such a digressive response on compression of the shock, rebound, or both, depending on the piston design. With digressive valving, undesirable high-speed damping forces can be eliminated without sacrificing low speed control. In modern technology both linear and digressive pistons are utilized to achieve optimum performance in a wide variety of racing and OEM markets. Such tuning of the shocks can affect performance and handling on wide ranges of bumps and other irregular road/track surfaces. Typically, a digressive valving will sacrifice a smooth ride for increased control at lower forces, and the force response will begin to level off relatively with higher shaft velocity, while linear valving will sacrifice some handling at the lower shaft velocities, and maintain a relatively linear force response as the shaft velocity increases. With this in mind, it may be desirable to develop a shock absorber that could combine different and tunable linear, digressive, and/or progressive responses.
According to various example embodiments of the present general inventive concept, a shock absorber valve assembly is provided that includes a linearizing plate configured to add linearization damping characteristics to a digressive bypass assembly, and/or a progressive support disk configured to add progressive damping characteristics to a linear valve assembly.
Additional aspects and advantages of the present general inventive concept will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the present general inventive concept.
The foregoing and/or other aspects and advantages of the present general inventive concept may be achieved by providing a valving assembly to cause linear damping response in a shock absorber having a digressive piston, the valving assembly including a linearizing plate having a first side configured to contact a ridge of a digressive piston proximate an outer edge of the first side, a second side, opposite the first side, configured to have a substantially flat surface, and a plurality of flow openings configured to allow fluid flow between the first and second sides of the linearizing plate.
The foregoing and/or other aspects and advantages of the present general inventive concept may also be achieved by providing a valving assembly to cause progressive damping response in a shock absorber having a linear piston face, the valving assembly including a support disk configured to be located at an end of the valving assembly opposite a piston of the shock absorber, and a metering shim configured to be placed adjacent to the support disk, wherein a side of the support disk facing the piston is configured with a stepped down recess configured to seat the metering shim therein, and wherein the metering shim is configured to have a smaller diameter than a cover shim arranged between the support disk and the piston so as to provide a predetermined gap between the support disk and the cover shim.
Other features and aspects may be apparent from the following detailed description, the drawings, and the claims.
The following example embodiments are representative of example techniques and structures designed to carry out the objects of the present general inventive concept, but the present general inventive concept is not limited to these example embodiments. In the accompanying drawings and illustrations, the sizes and relative sizes, shapes, and qualities of lines, entities, and regions may be exaggerated for clarity. A wide variety of additional embodiments will be more readily understood and appreciated through the following detailed description of the example embodiments, with reference to the accompanying drawings in which:
Reference will now be made to the example embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings and illustrations. The example embodiments are described herein in order to explain the present general inventive concept by referring to the figures.
The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the structures and fabrication techniques described herein. Accordingly, various changes, modification, and equivalents of the structures and fabrication techniques described herein will be suggested to those of ordinary skill in the art. The progression of fabrication operations described are merely examples, however, and the sequence type of operations is not limited to that set forth herein and may be changed as is known in the art, with the exception of operations necessarily occurring in a certain order. Also, description of well-known functions and constructions may be simplified and/or omitted for increased clarity and conciseness.
Note that spatially relative terms, such as “up,” “down,” “right,” “left,” “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over or rotated, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In shock assemblies, “bleed” is how much fluid a shock will bypass through a piston and valve stacks as it moves in either direction (compression and rebound). With a linear piston having a substantially flat face, a small bleed hole in the piston, along with a pyramid stack of valving disks, produces a linear damping response. With a digressive piston having a piston ring or ridge and corresponding lowered area or recess within the ridge allowing preloading of the pyramid stack, small valving disks may be placed in the recess to decrease the preload and simulate a linear damping response. Linear pistons may have more and larger bleed holes, and multiple pyramid stacks of valving disks, to produce a progressive damping response, while sacrificing low speed control.
In digressive valve stacks the bypass disk, or bypass bleed plate, affects low to mid-range rebound. The amount of bypass built into either linear or digressive valvings directly affects the low speed performance. With linear designs the bypass flow is balanced with the strength of the valve stack. It is the amount of bypass area that sets the parameters for the valve stack design with both linear and digressive pistons. In some configurations the bypass plate's thickness and number of slots, or flow openings, in its perimeter determine the bypass area. Testing has shown that more bypass area in the valve stack means less low speed damping force, and less bypass area means more low speed damping force. In other configurations the bypass plate, or bypass shim, is formed by a cover plate such that the cover plate diameter determines the bypass area due to open area of fluid holes. Typically, in such a valve stack, there are a variety of shims that are ordered (moving away from the piston) as a pre-load shim, the bypass shim, the cover shim, and a support shim. The number of various ones of these shims, as well as the diameters and thicknesses, vary according to different particular valve stacks. In a standard digressive stack, with the pre-load plate next to the piston, more thickness of the pre-load plate causes the cover plate to have less pre-load, and therefore less overall damping force in the stack. The bleed plate controls the low-speed damping forces, wherein more total bleed area means less damping force, and less bleed means more damping force. The cover plate or shim determines the overall force of the stack once the stack opens. Until the stack opens, only the bleed effects the valving. The support plate or brake washer fine tunes the high-speed damping force.
Various example embodiments of the present general inventive concept may provide a novel valve stack that improves performance by providing a shock absorber valve assembly that includes a linearizing plate, or linearization conversion plate, configured to add linearization damping characteristics to a digressive bypass assembly, and/or a progressive support disk configured to add progressive damping characteristics to a linear valve assembly. It is noted that the terms shock and shock absorber may be used interchangeably in the descriptions that follow. The terms disk, shim, plate, etc., may also be used interchangeably in portions of these descriptions.
The compression assembly 108 of this shock is a conventional digressive compression only bypass assembly including (listed in order in the direction of the piston 156) a support disk 112, a pair of clamp shims 116, a support shim 120, another support shim 122 of larger diameter than the support shim 120, a cover shim 124, a bleed shim 128 having a plurality of bleed openings 132 arranged around a perimeter of the bleed shim 128, a preload shim 136, a check valve spring 144, and a check valve plate 148 that is configured to be received in a recessed ring on the compression side face of the piston 156. The check valve spring 144 and check valve plate 148 form a check valve assembly 140. The check valve plate 148 is a compression only bypass (COB) valve.
The rebound assembly 168 of this shock, located on the rebound side of the piston 156, includes (in order leading away from the piston 156) a preload shim 172, a bleed shim 176 having a bleed opening 180 located on a perimeter of the bleed shim 176, a cover shim 184, a support shim 188, a pair of clamp shims 192, and a brake washer 196. A nut 200 is arranged to hold the piston assembly together on the piston rod 104.
During a compression operation of the shock, the check valve plate 148, which is configured to be seated in a corresponding recess of the digressive piston 156 to inhibit fluid flow through flow openings formed in that recess of the digressive piston 156, opens up to allow more fluid to flow. The bleed is additive, and in this example assembly the flow openings in the bleed shim 128 in the compression assembly 108 are equal to approximately 6 mm2, and the opening in the bleed shim 176 in the rebound assembly 168 is equal to approximately 0.27 mm2. Thus, during compression, this shock assembly has 6.27 mm2 of bleed area. When it is rebounding, the check valve spring 144 causes the check valve plate 148 to full seat in the digressive piston 156, shutting the flow openings formed in the recess that receives the check valve plate 148. Thus, there is only 0.27 mm2 of bleed area in the rebound. This is generally the configuration found in the BILSTEIN COB digressive piston assembly.
The rebound assembly 296 of this shock, located on the rebound side of the piston 284, includes (in order leading away from the piston 284) a cover shim 300, a plurality of support shims 304 formed with decreasing diameter moving away from the rebound side of the piston 284, a pair of clamp shims 308, and a brake washer 312. A nut 200 is arranged to hold the piston assembly together on the piston rod 104.
The basic difference between the linear piston 284 and the digressive piston 156 is the flat surface of the linear piston 284. Because the linear piston 284 does not have the piston ridge 260 and corresponding piston recess 256 inside the ridge 260, there is no way to pre-load the shims. The linear piston 284 works by the cover shims on the flat surface of the linear piston 284 simply opening, and from the diameter of the cover shims, which determine how much of the flow openings in the linear piston 284 are covered by the cover shims.
Thus, a stepped progressive support disk with a metering shim as described herein can be used in place of a conventional support disk. The metering shim may be used to set a gap between a cover shim and the progressive support disk, and the gap can be varied by changing the thickness of the metering shim or metering shims. When the cover shim flexes enough to come in contact with the progressive support disk, the flow window is fixed, and from that point on a progressive force response is achieved. In this way, progressive compression is achieved independently of a chosen bleed or clamp shim diameter, and flexibility is added in the stack underneath, in the support disk.
In various example embodiments a metering shim 332 may be provided adjacent to a conventional support disk 268 having a flat surface to produce the aforementioned gap between the cover shim 280 and the support disk 268, and to thus introduce progressive damping force to a linear stack assembly.
Various example embodiments of the present general inventive concept may provide a valving assembly to cause linear damping response in a shock absorber having a digressive piston, the valving assembly including a linearizing plate having a first side configured to contact a ridge of a digressive piston proximate an outer edge of the first side, a second side, opposite the first side, configured to have a substantially flat surface, and a plurality of flow openings configured to allow fluid flow between the first and second sides of the linearizing plate. The first side of the linearizing plate may be configured to contact the ridge of the digressive piston so as to prohibit fluid flow between the first side of the linearizing plate and the ridge of the digressive piston. The valving assembly may further include a sealing ring provided proximate the outer edge of the first side of the linearizing plate and configured to seal a space between the first side of the linearizing plate and the ridge of the digressive piston. The first side of the linearizing plate may include an outer ridge, an inner surface, and a channel formed between the outer ridge and inner surface, the plurality of flow openings being located in the channel. The valving assembly may further include a sealing ring provided on the outer ridge and configured to seal a space between the outer ridge of the linearizing plate and the ridge of the digressive piston. The valving assembly may further include a groove formed on the outer ridge and configured to at least partially receive the sealing ring. The inner surface may project higher than the outer ridge. The inner surface may be configured to compress a check valve spring and check valve plate against a surface of the digressive piston inside the ridge of the digressive piston. The flow openings may be configured to have substantially the same flow area as a flow area of the digressive piston inside the ridge of the digressive piston. The plurality of flow openings may be configured to allow control of bleed by varying an outer diameter of an adjacent cover shim. The valving assembly may further include another linearizing plate arranged on a ridge on an opposite side of the digressive piston in a substantially mirrored arrangement, so as to form a split-bleed linear piston assembly with the digressive piston.
Various example embodiments of the present general inventive concept may provide a valving assembly to cause progressive damping response in a shock absorber having a linear piston face, the valving assembly including a support disk configured to be located at an end of the valving assembly opposite a piston of the shock absorber, and a metering shim configured to be placed adjacent to the support disk, wherein a side of the support disk facing the piston is configured with a stepped down recess configured to seat the metering shim therein, and wherein the metering shim is configured to have a smaller diameter than a cover shim arranged between the support disk and the piston so as to provide a predetermined gap between the support disk and the cover shim. The side of the support disk facing the piston may include an outer surface, a middle surface stepped down from the outer surface, and an inner surface stepped down from the middle surface, wherein the inner surface is configured to seat the metering shim therein. The middle surface may be configured to have a diameter larger than a plurality of shims between the support disk and the cover shim, such that the cover shim contacts the outer surface when the cover shim flexes so as to contact the support disk. The valving assembly may be provided on both sides of the linear piston to cause progressive damping response on both compression and rebound sides of the linear piston. The linear piston face may be formed by a linearizing plate provided adjacent to a linear piston. Thus, valving assemblies on both the compression and rebound sides of a piston may include the linearizing plate and/or progressive support disk, depending on the type of piston and desired responses.
Numerous variations, modifications, and additional embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the present general inventive concept. For example, regardless of the content of any portion of this application, unless clearly specified to the contrary, there is no requirement for the inclusion in any claim herein or of any application claiming priority hereto of any particular described or illustrated activity or element, any particular sequence of such activities, or any particular interrelationship of such elements. Moreover, any activity can be repeated, any activity can be performed by multiple entities, and/or any element can be duplicated.
It is noted that the simplified diagrams and drawings included in the present application do not illustrate all the various connections and assemblies of the various components, however, those skilled in the art will understand how to implement such connections and assemblies, based on the illustrated components, figures, and descriptions provided herein, using sound engineering judgment. Numerous variations, modification, and additional embodiments are possible, and, accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the present general inventive concept.
While the present general inventive concept has been illustrated by description of several example embodiments, and while the illustrative embodiments have been described in detail, it is not the intention of the applicant to restrict or in any way limit the scope of the general inventive concept to such descriptions and illustrations. Instead, the descriptions, drawings, and claims herein are to be regarded as illustrative in nature, and not as restrictive, and additional embodiments will readily appear to those skilled in the art upon reading the above description and drawings. Additional modifications will readily appear to those skilled in the art. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.