Patent Publication Number: US-11649872-B2

Title: Shock absorber dust gaiter with improved installation

Description:
TECHNICAL FIELD 
     Example embodiments generally relate to vehicle suspension and, more particularly, relate to a suspension system with an easy to install dust gaiter for a suspension damper or shock absorber. 
     BACKGROUND 
     Vehicles commonly employ independent suspension that allows each wheel to move relative to the vehicle chassis independent of the other wheels. The components and geometries used for independent suspension designs can vary to some degree. However, a typical independent suspension system will employ dampers or shock absorbers (or simply “shocks”) that are designed to provide damping for pitch (i.e., oscillation about a lateral axis of the vehicle). The shocks generally resist compression and rebound with damping forces that are applied over a range of travel of a piston rod. 
     The shocks selected for a particular vehicle are generally chosen based on the expectation of normal pitch scenarios that are encountered during routine driving conditions. Some typical suspension components that may be considered for selection include springs and dampers (e.g., gas shocks). Moreover, some shocks employ what is referred to as a coil-over design in which a coil spring is provided coaxial with the damper such that the damper is inside the coil spring. These coil-over shocks often employ some form of dust gaiter or bellows that is used to prevent dust, dirt or debris from fouling the interface between the rod and the damper tube of the damper or shock. In a typical situation, a bumper cap may be used to provide a seating surface for the dust gaiter on the damper tube. The dust gaiter is typically assembled onto the bumper cap through the coils of the spring by hand, which generally makes such installation relatively difficult to achieve since clearance between the coils can vary. 
     BRIEF SUMMARY OF SOME EXAMPLES 
     In accordance with an example embodiment, a shock absorber for a vehicle suspension system may be provided. The shock absorber may include a damper tube having an axis defining an axial direction extending between a first end and a second end, a bumper cap, and a dust gaiter operably coupled to the bumper cap. The bumper cap may have a cover portion and a retention portion. The cover portion may be operably coupled to the second end of the damper tube, and the retention portion may extend along a lateral periphery of the damper tube to an opposite end of the bumper cap relative to the cover portion. The retention portion may include a continuous ring at a distal end of the bumper cap relative to the cover portion to define a limit for movement of the dust gaiter along the bumper cap in the axial direction. The continuous ring may be retained by a plurality of fixed fingers that extend from the cover portion to the continuous ring. A movable finger is disposed between each of the fixed fingers, each instance of the movable finger having a radially extending locking tab to engage the dust gaiter. Each instance of the moveable finger has a radial deflection rate of less than about 8 N/mm. 
     In another example embodiment, a bumper cap for a shock absorber of a vehicle suspension system may be provided. The bumper cap may include a cover portion for interfacing with a damper tube of the shock absorber, and a retention portion. The damper tube may have an axis defining an axial direction extending between a first end and a second end. The retention portion may extend along a lateral periphery of the damper tube to an opposite end of the bumper cap relative to the cover portion. The retention portion may include a continuous ring at a distal end of the bumper cap relative to the cover portion to define a limit for movement of a dust gaiter along the bumper cap in the axial direction. The continuous ring may be retained by a plurality of fixed fingers that extend from the cover portion to the continuous ring. A movable finger may be disposed between each of the fixed fingers. Each instance of the movable finger may have a radially extending locking tab to engage the dust gaiter. The moveable finger may have a radial deflection rate of less than about 8 N/mm. 
     In yet another example embodiment, a suspension system for a vehicle may be provided. The suspension system may include a chassis, a wheel, and a coil-over shock absorber operably coupling the chassis and the wheel. The shock absorber may include a damper tube having an axis defining an axial direction extending between a first end and a second end, a bumper cap having a cover portion and a retention portion, and a dust gaiter operably coupled to the bumper cap. The cover portion may be operably coupled to the second end of the damper tube, and the retention portion may extend along a lateral periphery of the damper tube to an opposite end of the bumper cap relative to the cover portion. The retention portion may include a continuous ring at a distal end of the bumper cap relative to the cover portion to define a limit for movement of the dust gaiter along the bumper cap in the axial direction. The continuous ring may be retained by a plurality of fixed fingers that extend from the cover portion to the continuous ring. A movable finger may be disposed between each of the fixed fingers. Each instance of the movable finger may have a radially extending locking tab to engage the dust gaiter. The moveable finger may have a radial deflection rate of less than about 8 N/mm. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG.  1    illustrates a block diagram of a vehicle suspension system in accordance with an example embodiment; 
         FIG.  2    illustrates a cross section view of a coil-over shock absorber in accordance with an example embodiment; 
         FIG.  3   , which is defined by  FIGS.  3 A and  3 B , illustrates bottom and top perspective views of a damper bump cap in accordance with an example embodiment; 
         FIG.  4    illustrates a side view of the damper bump cap of  FIG.  3    in accordance with an example embodiment; 
         FIG.  5    is a cross section view of the damper bump cap taken along line A-A′ of  FIG.  4    in accordance with an example embodiment; 
         FIG.  6    is a side view showing installation of a dust gaiter onto the damper bump cap in accordance with an example embodiment; 
         FIG.  7    illustrates a cross section view showing an impact of insertion of the dust gaiter onto the damper bump cap in accordance with an example embodiment; 
         FIG.  8    is a side view showing an attempted removal of the dust gaiter from the damper bump cap in accordance with an example embodiment; and 
         FIG.  9    illustrates a cross section view showing an impact of the attempted removal of the dust gaiter from the damper bump cap in accordance with an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. Furthermore, as used herein, the term “or” is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, operable coupling should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection of components that are operably coupled to each other. 
     Some example embodiments described herein may address the problems described above. In this regard, for example, some embodiments may provide an improved shock or suspension system design that employs easy to install dust gaiters. In this regard, for example, some embodiments may provide for a self-seating dust gaiter based on the structures employed on the damper bumper cap (or bump cap). As a result, installation may require little effort, and the dust gaiter may even be seated automatically (e.g., self-seating in response to jounce movements). 
       FIG.  1    illustrates a block diagram of a vehicle suspension system  100  employing a coil-over damper  110 . The suspension system  100  employs the coil-over damper  110  to dampen jounce and rebound forces that may be initiated between a body or chassis  120  of the vehicle and a wheel  130  (or wheel assembly components). In this regard, the coil-over damper  110  operably couples the chassis  120  to the wheel  130 . The coil-over damper  110  may include a strut module or damper tube  140  with a rod  142  that extends into the damper tube  140 . The rod  142  may be operably coupled to the damper tube  140  in such a way as to resist movement of the rod  142  via gas, fluid, springs, or other damping media that may be disposed within the damper tube  140 . 
     As noted above, the coil-over damper  110  may include a coil spring  144  that extends over at least a portion of the damper tube  140 . It may be desirable to prevent any dust or debris from getting into the interface between the rod  142  and the damper tube  140 . To provide a seal against such dust or debris, a damper bump cap  150  may be provided to support dust gaiter (or bellows)  160 . The dust gaiter  160  may be affixed to the damper tube  140  via the damper bump cap  150 . To avoid any requirement for the operator to reach through the coils of the coil spring  144  to attempt to seat the dust gaiter  160  onto the damper bump cap  150 , the damper bump cap  150  may be designed with structural features as described in greater detail below to provide easy effort installation that may, in some cases, actually also be self-seating. 
       FIG.  2    shows a specific example of some structures that may be employed to instantiate the components described above. In this regard, coil-over damper  210 , which is illustrated in  FIG.  2    includes damper tube  240  (or strut module) with a rod  242  that extends into the damper tube  240 . The damper tube  240  has a first end  246  and a second end  248  that is opposite the first end  246 . The coil spring  244  that extends over at least a portion of the damper tube  240  (e.g., the first end  246  in this example), and around an interface between the rod  242  and the damper tube  240 . 
     The damper tube  240  may also have an axis  249  that extends from the first end  246  to the second end  248 . The axis  249  may also be aligned with an axis of the rod  242 , and may further be coaxial with the coil spring  244  in some cases. A damper bump cap  250  (or bumper cap) may be operably coupled to the second end  246  of the damper tube  240  to support dust gaiter  260 . Thus, the dust gaiter  260  may be easily affixed to the damper tube  240 , and reliably retained thereto, via the damper bump cap  250 . The damper bump cap  250  may be provided with flexible clips  270  as described in greater detail below in order to attach the dust gaiter  260  to the damper bump cap  250  in this manner. 
     An example of the damper bump cap  250  is shown in greater detail in  FIGS.  3 ,  4  and  5   . In this regard,  FIG.  3   , which is defined by  FIGS.  3 A and  3 B , shows perspective views of the damper bumper cap  250  from bottom and top perspectives, respectively.  FIG.  4    illustrates a side view of the damper bumper cap  250 , and  FIG.  5    shows a perspective view of a cross section taken along line A-A′ of  FIG.  4   . 
     Referring now to  FIGS.  3 - 5   , the damper bump cap  250  may have a cover portion  300  and a retention portion  310 . The cover portion  300  may have a circular end plate  320  having a rod aperture  322  formed at a center thereof. The rod  242  may extend through the rod aperture  322  with a relatively small clearance. The cover portion  300  may also include a sidewall portion  324  that extends away from the end plate  320  in one direction. The sidewall portion  324  may be substantially continuous as it extends away from the end plate  320  in the one direction such that the end plate  320  and the sidewall portion  324  combine to form a cylindrical cup. The cover portion  300  may be operably coupled to the second end  248  of the damper tube  240  to substantially seal the interface between the damper tube  240  and the rod  242 . 
     The retention portion  310  may extend along a lateral periphery of the damper tube  240  proximate to the second end  248 . The retention portion  310  may extend away from the cover portion  300  (e.g., to an opposite end or distal end of the damper bump cap  250  relative to the cover portion  300 ). The retention portion  310  may be defined by a continuous ring  330  at the distal end of the damper bump cap  250  relative to the cover portion  300 . The continuous ring  330  may define a limit for movement of the dust gaiter  260  along the damper bump cap  250  in the axial direction when the dust gaiter  260  is installed onto the damper bump cap  250 . The continuous ring may  330  be retained by a plurality of fixed fingers  332  that extend from the cover portion  300  to the continuous ring  330 . In some cases, the fixed fingers  332  may extend away from a distal end of the sidewall portion  324  of the cover portion  300 . Moreover, it may be possible, in some cases, for the sidewall portion  324  to be eliminated such that the fixed fingers  322  may extend away from the end plate  320 . 
     In an example embodiment, a movable finger  340  may be disposed between each adjacent one of the fixed fingers  332 . Thus, for example, each instance of the movable finger  340  may extend away from the sidewall portion  324  (or the end plate  320 ) in a gap  342  formed between each of the adjacent pairs of fixed fingers  332 . The movable fingers  340  may each have a radial deflection rate of less than about 8 N/mm. This stands in contrast to the stiffer fingers of structurally different conventional caps, which tend to range between about 10-15 N/mm. Moreover, some example embodiments may provide the movable fingers  340  to have a radial deflection rate of between about 0.5 N/mm and 4 N/mm. The depicted example has a measured radial deflection rate of less than about 1 N/mm. Each movable finger  340  may have a finger body  344  that extends axially toward the continuous ring  330  in the gap  342  and may terminate at a radially extending locking tab  350  to engage the dust gaiter  260 . Notably, the radial deflection rate noted above may be measured at the locking tabs  350 . Each moveable finger  340  has a length (L M ) of greater than about 60% of a length (LF) of the fixed fingers  332  (and therefore also the axial length of the gap  342 ). Moreover, in some embodiments, the length (L M ) of the movable finger  340  may be as much as 90% to 95% of the length (LF) of the fixed fingers  332 . 
     By making the movable fingers  340  relatively long compared to the fixed fingers  332 , the movable fingers  340  are given a greater amount of flexibility. The flexibility may be enhanced by making the movable fingers  340  thinner than the fixed fingers  332  as well. In this regard, for example,  FIG.  5    shows a thickness (T M ) of the movable finger  340  may be less than a thickness (T F ) of the fixed fingers  332 . For example, if the thickness (T M ) of the movable finger  340  is about 2 mm in one case, then the thickness (T F ) of the fixed fingers  332  may be about 2.6 mm. In some embodiments, the thickness (T M ) of the movable finger  340  may be between about 60% to about 80% of the thickness (T F ) of the fixed fingers  332 . Meanwhile, a width of the movable finger  340  may be greater than a width of the fixed fingers  332 , and such width may decrease as distance from the continuous ring  330  decreases. In other words, the movable fingers  340  may get less wide as they extend toward the locking tabs  350 . An inner diameter of the cover portion  300  at the end plate  320  may be less than an inner diameter of the retention portion  310  at the continuous ring  330  to provide some space between the inside of the movable finger  340  and the outer periphery of the damper tube  240  to enable the movable finger  340  to flex inwardly. The thinner nature of the movable finger  340  relative to the fixed fingers  332  may add additional clearance to provide space for movement and flexibility of the movable fingers  340 . This structure provides an installation force to fully seat the dust gaiter  260  onto the damper bump cap  250  with an even force on all of the locking tabs  350  that is below about 25 N. Meanwhile, conventional caps typically require a force of between about 70-110 N. 
     The locking tab  350  at the distal end of each respective one of the movable fingers  340  may be a same distance (i.e., the length (L M )) from the end plate  320 . Moreover, the outer periphery of the locking tabs  350  may combine to form a discontinuous ring as compared to the continuous ring  330 . The discontinuous ring is also equidistant from the continuous ring  330  at all points thereof. The discontinuous ring forms a flexible engagement interface to retain the dust gaiter  260  on the damper tube  240 , whereas the continuous ring  330  prevents movement beyond the continuous ring  330  in the axial direction. Thus, the dust gaiter  260  may reliably installed onto the damper bump cap  250  without any need to fully seat the dust gaiter  260  on the discontinuous ring. Instead, any jounce event that compresses the coil-over damper  210  will tend to push the dust gaiter  260  until the discontinuous ring engages the dust gaiter  260  to retain the dust gaiter  260  as shown in reference to  FIGS.  6 - 9   . 
       FIG.  6    shows how the dust gaiter  260  being installed over the damper bumper cap  250  in accordance with an example embodiment, and  FIG.  7    illustrates a cross section view of the damper bumper cap  250  to show the results at the damper bumper cap  250  that occur responsive to such installation. In this regard, the dust gaiter  260  may have a first end  400  and a second end  410 . The dust gaiter  260  may have sidewalls  420  that extend from the first end  400  to the second end  410 , and the sidewalls  420  may include radial grooves and ridges that define a waved pattern that repeats from the first end  400  to the second end  410 . The waved pattern may provide some amount of flexibility for expandability or retractability as the dust gaiter  260  extends or contracts responsive to rebound and jounce events. 
     The first end  400  may interface with and/or be secured to a portion of the chassis or body, or an intermediate component attached thereto. The second end  410  may slide over the damper bump cap  250  until a retention groove  430  disposed proximate to the second end  410  is able to interface with the locking tabs  350 . In this regard, for example, the material of the dust gaiter  260  that forms the retention groove  430  may slide over the locking tabs  350  responsive to lowering of the damper bump cap  250  (e.g., in the direction of arrow  440 ), and may push or urge the locking tabs  350  inward. The movable fingers  340  may then move inwardly (e.g., toward the outer peripheral sides of the damper tube  240 ) by pivoting as shown by arrows  450  in  FIG.  7   . Once the locking tabs  350  are aligned with the retention groove  430 , the locking tabs  350  may engage the retention groove  430  to retain the second end  410  of the dust gaiter  260  on the damper bump cap  250 .  FIG.  7    shows a distance (D) that the locking tabs  350  may move inwardly responsive to the operations described above, and the position of the locking tabs  350 ′ in  FIG.  7    shows the deflected location to which the locking tabs  350  are moved. Notably, the second end  410  of the dust gaiter  260  may not be urged past the continuous ring  330 , and the continuous ring  330  may therefore define a limit to the movement of the dust gaiter  260  in the axial direction (shown by arrow  440 ). 
       FIG.  8    illustrates a cross section view of the dust gaiter  260  and the damper bump cap  250  to show the locking tabs  350  engaged in the retention groove  430 . When a force is exerted upwardly as shown by arrow  460  in  FIG.  8   , the locking tabs  350  may be urged outwardly to an extended position shown by locking tabs  350 ″ in  FIG.  9   . A deflection distance (DD) may be defined by this force exertion, and the locking tabs  350  may actually engage the retention groove  430  more deeply, and prevent removal of the dust gaiter  260 . The effective diameter of the discontinuous ring formed by the locking tabs  350  may therefore decrease for easy installation, and increase for prevention of removal of the dust gaiter  260  from the damper bump cap  250 . Thus, as can be appreciated from  FIG.  6 - 9   , a relatively low installation force (including a jounce event) may be used to seat (or self-seat) the dust gaiter  260  onto the damper bump cap  250 . However, a higher retention force is created. Moreover, the thickness of the movable fingers  340  may be made thinner to provide more flexibility, or thicker to reduce flexibility. As such, the thickness of the movable fingers  340  may be adjusted to “tune” the installation force to a desired level (e.g., to permit self-seating instead of manual engagement of the dust gaiter  260  by reaching through spring coils). In this regard, a typical bump cap can only adjust a diameter of the cap portion and/or retention portion in order to change the retention force. However, increasing retention force necessarily also requires an increase in the force needed for installation. Meanwhile, example embodiments decouple these competing interests, so that increased retention force can be achieved while also increasing the ease of install (i.e., reducing the installation forces needed). 
     A shock absorber for a vehicle suspension system of an example embodiment may therefore be provided. The shock absorber may include a damper tube having an axis defining an axial direction extending between a first end and a second end, a bumper cap, and a dust gaiter operably coupled to the bumper cap. The bumper cap may have a cover portion and a retention portion. The cover portion may be operably coupled to the second end of the damper tube, and the retention portion may extend along a lateral periphery of the damper tube to an opposite end of the bumper cap relative to the cover portion. The retention portion may include a continuous ring at a distal end of the bumper cap relative to the cover portion to define a limit for movement of the dust gaiter along the bumper cap in the axial direction. The continuous ring may be retained by a plurality of fixed fingers that extend from the cover portion to the continuous ring. A movable finger is disposed between each of the fixed fingers, each instance of the movable finger having a radially extending locking tab to engage the dust gaiter. Each instance of the moveable finger has a radial deflection rate of less than about 8 N/mm. In some cases, the radial deflection rate may be between about 0.5 to about 4 N/mm. 
     The shock absorber of some embodiments may include additional features, modifications, augmentations and/or the like to achieve further objectives or enhance performance of the device. The additional features, modifications, augmentations and/or the like may be added in any combination with each other. Below is a list of various additional features, modifications, and augmentations that can each be added individually or in any combination with each other. For example, the moveable finger may have a length of greater than about 60% of a length of the fixed fingers (or greater than 90% in some cases). In an example embodiment, the movable finger may be thinner than the fixed fingers. In some cases, a thickness of the movable finger may be between about 60% to about 80% of a thickness of the fixed fingers. In an example embodiment, the movable finger may be wider than the fixed fingers. In some cases, each instance of the locking tab may combine with all of the other instances of the locking tab to form a discontinuous ring that is parallel to and spaced apart from the continuous ring. In an example embodiment, a diameter of the discontinuous ring decreases when the dust gaiter is inserted onto the bumper cap. In some cases, a diameter of the discontinuous ring may increase when a force is exerted on the dust gaiter in a direction tending to remove the dust gaiter from the bumper cap. In an example embodiment, a gap may be formed between adjacent ones of the fixed fingers, and the movable finger may be formed in the gap and spaced apart from edges of the fixed fingers. In some cases, each instance of the movable finger may be flexible inwardly to enable self-seating of the dust gaiter onto the bumper cap responsive to a jounce event. In an example embodiment, each instance of the movable finger may be flexible outwardly to prevent removal of the dust gaiter from the bumper cap. In some cases, a width of the movable finger may decrease as distance from the continuous ring decreases. 
     Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. In cases where advantages, benefits or solutions to problems are described herein, it should be appreciated that such advantages, benefits and/or solutions may be applicable to some example embodiments, but not necessarily all example embodiments. Thus, any advantages, benefits or solutions described herein should not be thought of as being critical, required or essential to all embodiments or to that which is claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.