Abstract:
Methods and apparatus for a damper adjustment assembly that comprises an adjuster having a first detent at a first axial location, and a second detent at a second axial location. The assembly may further comprise a housing having a keeper for engaging the first and second detents. The method may comprise rotating the adjuster within the housing, and engaging the keeper with the first detent at the first axial location. The method may further comprise further rotating the damping adjuster within the housing and engaging the keeper with the second detent at the second axial location on the adjuster.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional patent application Ser. No. 61/296,874, filed Jan. 20, 2010, which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention generally relates to methods and apparatus for enhanced resolution of a ball detent type retainer for use with parameter adjustment mechanisms. More specifically, embodiments generally relate to methods and apparatus for use with suspension system dampers. In particular, embodiments relate to a variable damping adjuster for adjusting characteristics of a vehicle suspension system. 
     2. Description of the Related Art 
     Many vehicles today have suspension systems that are configured to let the vehicle wheels move up and down to absorb the shock when encountering uneven terrain, while keeping the wheels in contact with the ground. Suspension systems generally contain two elements, a spring and a damper. These two components are sometimes collectively referred to as a shock absorber. In some configurations, the damper alone is referred to as a “shock absorber.” 
     It is often desirable to have a suspension system that is adjustable, so that the operator of the vehicle can have an optimum riding experience on different types of terrain. Since there are numerous types of terrain over which the vehicle may be driven, it may be difficult to provide such a suspension system that can be easily tunable to each environment. Therefore, there is a continuous need for suspension systems that are easily adjustable and can provide an optimum range of shock absorption for any given terrain. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a parameter adjuster indexing mechanism having enhanced resolution is provided. In one embodiment, a vehicle suspension damper for providing a variable damping rate may comprise an adjuster having a first detent at a first axial location and a second detent at a second axial location; and a housing having a keeper for engaging the first and second detents. 
     In one embodiment, an adjustment assembly may comprise a shaft having a first detent disposed at a first axial location on an outer surface of the shaft, and a second detent disposed at a second axial location on the outer surface of the shaft. The assembly may further comprise a retaining member for engaging the first and second detents and a biasing member operable to bias the retaining member into engagement with at least one of the first and second detents. 
     In one embodiment, a method for altering the damping rate of a vehicle suspension damper may comprise rotating a damping adjuster, within a housing; engaging a keeper with a first detent at a first axial location on the adjuster; further rotating the damping adjuster within the housing; and engaging the keeper with a second detent at a second axial location on the adjuster. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features can be understood in detail, a more particular description may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  illustrates a cross-sectional view of a shock absorber according to one embodiment. 
         FIGS. 2 and 3  illustrate a blown-up cross-sectional view of a housing assembly of the shock absorber according to one embodiment. 
         FIG. 4  illustrates an adjustment shaft and detent mechanism of the shock absorber according to one embodiment. 
         FIG. 5  illustrates the adjustment shaft in a first adjustment position. 
         FIG. 6  illustrates a cross-sectional view of the ball and detent mechanism in the first adjustment position. 
         FIG. 7  illustrates the adjustment shaft in a second adjustment position. 
         FIG. 8  illustrates a cross-sectional view of the ball and detent mechanism in the second adjustment position. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments described herein may be used with the embodiments described in U.S. Provisional Patent Application Ser. No. 61/083,478, filed Jul. 24, 2008, and U.S. patent application Ser. No. 12/509,258, filed Jul. 24, 2009, and each of those applications is herein incorporated by reference in its entirety. 
     One embodiment hereof comprises an adjuster for a vehicle shock absorber damper. In one embodiment the vehicle is a bicycle. The shock absorber is advantageous because it includes a damper having a manually adjustable damping resistance. In one embodiment, the manually adjustable damping function allows a user to adjust a “platform” or “blow off” threshold which must be exceeded before the shock absorber can experience significant compression travel. It allows the user to establish a level, in one embodiment, for compression damping whereby such damping is increased or decreased selectively. A bicycle rider for example may choose to set a fairly high threshold for the function of compression damping thereby reducing pedal induced suspension bob. In one embodiment the adjuster is for a bicycle or motorcycle fork. 
     U.S. Pat. No. 6,135,434, which patent is herein incorporated by reference in its entirety, shows certain variations of positive and negative spring mechanisms. Another selectively variable damping mechanism is shown in U.S. Pat. No. 6,360,857, which patent is herein incorporated by reference in its entirety. Optionally, any of the foregoing mechanisms may be integrated, or used in combination, with any other features disclosed herein. 
     U.S. Pat. Nos. 6,415,895, 6,296,092, 6,978,872 and 7,308,976, each of which patents is herein incorporated by reference in its entirety, show certain variations of position sensitive damping mechanisms. Another position sensitive damping mechanism is shown in U.S. Pat. No. 7,374,028, which patent is herein incorporated by reference in its entirety. Another position sensitive damping mechanism is shown in U.S. Pat. No. 5,190,126, which patent is herein incorporated by reference in its entirety. Optionally, any of the foregoing mechanisms may be integrated, or used in combination, with any other features disclosed herein. 
     U.S. Pat. Nos. 6,581,948, 7,273,137, 7,261,194, 7,128,192, and 6,604,751, each of which patents is herein incorporated by reference in its entirety, show certain variations of inertia valve mechanisms for controlling aspects of compression damping. Additionally, U.S. Published Patent Application Nos. 2008/0053768 A1, 2008/0053767 A1, 2008/0035439 A1, 200810007017 A1, 2007/0296163 A1, 2007/0262555 A1, 2007/0228691A1, 2007/0228690 A1, 2007/0227845 A1, 2007/0227844 A1, 2007/0158927 A1, 2007/0119670 A1, 2007/0068751A1, 2007/0012531A1, 2006/0065496 A1, each of which patent applications is herein incorporated by reference in its entirety, show certain variations of inertia valve mechanisms for controlling aspects of compression damping. Optionally, any of the foregoing inertia valve mechanisms or other features may be integrated, or used in combination, with any other features disclosed herein. A shock absorber or fork may be equipped, for example, with an inertia valve for controlling an aspect of damping and a position sensitive valve for controlling another aspect of damping. 
     In one embodiment, both compression and rebound damping are selectively adjustable by the user. Optionally, any of the features described herein may be adapted for integration into a bicycle or motorcycle fork. For example, FIGS. 14 through 25, of U.S. Pat. No. 7,273,137 (incorporated herein by reference) show an embodiment of a vehicle suspension fork that may be integrated with features hereof. Additionally, U.S. Pat. No. 6,592,136, which patent is herein incorporated by reference in its entirety, shows embodiments of a vehicle suspension fork that may be integrated with features hereof. Additionally, Published U.S. Patent Applications 2007/0119672 A1 and 2007/0007743 A1, each of which applications is herein incorporated by reference in its entirety, show embodiments of a vehicle suspension fork that may be integrated with features hereof. 
       FIGS. 1 ,  2 , and  3  illustrate an embodiment of a shock absorber  100  and a housing assembly  10  which includes a damper adjuster assembly, generally described herein as a rebound metering cam shaft  90 . Although described herein with respect to a rebound metering cam shaft, the embodiments of the damper adjuster assembly may be used with any other components of a shock absorber system. In addition, although described herein with respect to a shock absorber system, the embodiments of the damper adjuster assembly may be used with any systems having or needing an adjuster-type feature and/or a damper adjuster-type feature. In one embodiment, the shock absorber  100  may be configured with a variable gas spring system and/or a mechanical spring system. U.S. Pat. No. 6,360,857, which patent is entirely incorporated herein by reference, shows an embodiment of an adjuster assembly with which the present improvements may be used. 
       FIG. 1  shows an embodiment of the shock absorber  100 . The shock absorber  100  includes the housing assembly  10 , and a body  40  slidably (axially) disposed in a sleeve assembly  20 . The sleeve assembly  20  is connected, by helical threads, to the housing assembly  10  and forms a seal therewith by a seal  19 . A bearing assembly  30  is connected to an end of the body  40  by threads and is fluid sealed in relation thereto by a seal  32 , and is also fluid sealed to shaft  22  via seal  31  and sleeve assembly  20  via seal  33 . An inner compression rod  26  is disposed approximately concentrically within a rebound metering rod  24 , and a seal  18  is provided therebetween. The rods  26 ,  24  are disposed approximately concentrically within a shaft  22 , and a seal  16  is also provided between the rod  24  and the shaft  22 . The shaft  22  is threaded at a first end in sealing engagement, via seal  17 , into housing assembly  10 . A piston assembly  60  is threaded into a second end of the shaft  22  by means of a piston bolt  66 . A floating piston assembly  50  and a seal  51  (e.g. “a movable barrier”) are disposed within and axially movable in relation to the body  40 . The floating piston assembly  50  divides an interior of the body  40  into a damping fluid chamber  45  and a compressible chamber  55 . A plug member  53  may be used to open and close a fluid port to fill the compressible chamber  55 . Eyelets  11  and  52  may be formed at the ends of the shock absorber for connection to a vehicle. A spring chamber  25  is formed by the housing assembly  10 , the sleeve assembly  20 , and the bearing assembly  30 . In one embodiment, an example of a shock absorber  100  that may be used with the embodiments described herein is provided in U.S. Provisional Patent Application Ser. No. 61/083,478, filed Jul. 24, 2008, and U.S. patent application Ser. No. 12/509,258, filed Jul. 24, 2009, each of which applications is herein incorporated by reference in its entirety. 
     In operation, an axial compressive force exerted on the shock absorber  100  causes the body  40  and attached bearing assembly  30  to move axially further into the interior of the sleeve assembly  20 . In so moving, the body  40  and the bearing assembly  30  also move axially relative to the piston assembly  60 , the shaft  22 , the rods  24 ,  26 , and the housing assembly  10 . During that movement, gas in the spring chamber  25  is compressed and thereby stores energy for release during rebound. Compression damping occurs as damping fluid in the damping fluid chamber  45  is forced to move from a first side of the piston assembly  60  to a second side of the piston assembly  60  through one or more flow paths, typically disposed through the piston assembly  60  and having varying degrees of designed resistance to flow through. Rebound damping occurs as the damping fluid then returns from the second side of the piston assembly  60  to the first side through one or more flow paths, typically disposed through the piston assembly  60  and having varying degrees of designed resistance to flow through. 
     In one embodiment, the piston assembly  60  determines the operational fluid flow paths through which the damping fluid may flow and thereby dictates the degree of damping available. In one embodiment, the piston assembly  60  is configured so that certain fluid flow paths are open for compression damping and certain other flow paths are open for rebound damping, thereby allowing for differing degrees of damping during shock compression versus shock rebound. In one embodiment, an example of a piston assembly  60  that may be used with the embodiments described herein is provided in U.S. Provisional Patent Application Ser. No. 61/083,478, filed Jul. 24, 2008, and U.S. patent application Ser. No. 12/509,258, filed Jul. 24, 2009, each of which applications is herein incorporated by reference in its entirety. 
     As the body  40  moves further into the sleeve assembly  20  during compression, the shaft  22  further enters the volume of the damping fluid chamber  45  and occupies and thereby reduces available fluid volume therein. In one embodiment, the compressible chamber  55  is filled with a compressible fluid such as a gas and/or is preloaded at an elevated pressure. In one embodiment, the damping fluid chamber  45  is filled with a liquid damping fluid that is relatively incompressible. As the shaft  22  enters the damping fluid chamber  45  and reduces the fluid volume therein, the relatively incompressible damping fluid is displaced. The volume of the damping fluid chamber  45  is therefore correspondingly increased to compensate for the reduction, due to the incursion of the shaft  22 , by movement of the floating piston assembly  50  such that the gas in the compressible chamber  55  is compressed or further compressed. The floating piston assembly  55  is configured for transferring pressure from the damping fluid chamber  45  to the compressible chamber  55 . The floating piston assembly  50  moves to reduce the volume of the compressible chamber  55  (and compressing the fluid therein) while increasing (i.e. compensating) the volume of the damping fluid chamber  45 . 
     In one embodiment, as the shaft  22  moves into the damping fluid chamber  45  and towards the compressible chamber  55 , the inner compression rod  26  may be biased at one end by a damping adjustment spring  62 , which also biases a damping adjustment valve  65 . At the same time, pressure within the damping fluid chamber  45  increases. This increased pressure pushes against the damping adjustment valve  65  against the bias of the damping adjustment spring  62 . If the pressure overcomes the seating force of the damping adjustment valve  65 , then an aperture  68  opens up and allows damping fluid to flow through to the opposite side of the piston assembly  60 . The damping fluid may flow through one or more channels  67  to the other side of the piston assembly  60 . Adjusting the amount of preload on the damping adjustment spring  62  by axially moving the compression rod  26  toward and away from the piston assembly  60 , thereby adjusts the damping rate of the shock absorber  100 . 
     In one embodiment, as the shaft  22  moves out of the damping fluid chamber  45  and away from the compressible chamber  55 , a rebound metering spring  28  is pushing the rebound metering rod  24  away from the piston assembly  60 . The rebound metering spring  28  is disposed between an inner shoulder of the shaft  22  and an outer shoulder of the rebound metering rod  24 . At the same time, the rebound metering rod  24  and the piston assembly  60  allow the damping fluid to flow from the opposite side of the piston assembly  60  back into the damping fluid chamber  45 . The damping fluid may flow through one or more channels that are metered by the rebound metering rod  24  depending on its axial position relative to the piston assembly  60 . Adjusting the axial position of the rebound metering rod  24 , e.g. moving the rebound metering rod  24  toward and away from the piston assembly  60 , thereby adjusts the rebound rate of the shock absorber  100 . For example, when the rebound metering rod  24  is in a first position relative to the piston assembly  60 , the rebound damping fluid may flow more freely from above the piston assembly  60  to below the piston assembly  60  during extension of the body  40  from the sleeve assembly  20 . Therefore the shock absorber  100  extends more rapidly. And when the rebound metering rod  24  is moved axially to a second position, the rebound damping fluid may flow less freely from above the piston assembly  60  to below the piston assembly  60 . Therefore the shock absorber  100  extends more slowly. 
     The axial positions of the rebound metering rod  24  and the compression rod  26  may be selectively adjusted by rotation of a first damper adjuster, such as a rebound metering cam shaft  90 , and a second damper adjuster, such as a compression cam shaft  76 , respectively, that are each rotatably mounted within a recess  71  of the housing assembly  10 . The compression cam shaft  76  may include one or more lobes  77  of varying height that engage an upper end of the compression rod  26  via a ball member  78  to axially move the compression rod  26  toward and away from the damping adjustment spring  62 . Rotation of compression cam shaft  76  moves the lobes  77  into engagement with the compression rod  26  to cause axial displacement thereof and correspondingly alter the damper adjustment spring  26  preload to adjust damping rates. A connecting rod  73  may be disposed through the compression cam shaft  76 , and may engage a spring  72  disposed within an end of the compression cam shaft  76  at one end and coupled to a knob  70  at the opposite end. A lever  75  may also be coupled to the compression cam shaft  76 . 
     Similarly, the rebound metering cam shaft  90  may include a varying outer diameter surface  96  that engages an upper end of the rebound metering rod  24  to axially move the rod  24  toward and away from the piston assembly  60  against the bias of the rebound metering spring  28 . Rotation of the rebound metering cam shaft  90  causes rotation of the outer diameter surface  96 , which surface abuts a portion of an upper end of the rebound metering rod  24 , and corresponding axial movement of the rebound metering rod  24 . Axial movement of the rod  24  allows or obstructs rebound damping fluid flow through the piston assembly  60 . A ball and spring assembly  80  may be disposed within the housing assembly  10  to engage one or more detents that are formed on the outer surface of the rebound metering cam shaft  90 . The ball and detent mechanism as further discussed below is configured to assist with selective adjustment and maintenance of the axial position of the rebound metering rod  24  by rotation of the rebound metering cam shaft  90 . 
       FIGS. 2 and 3  illustrate a first and second axial position of the rebound metering rod  24  corresponding to contact with the varying outer “diameter” surface  96  of the rebound metering cam shaft  90 . The rotational position of the rebound metering cam shaft  90  is supported by a retaining member or a keeper, such as ball  85 , that is biased by a spring  87  into engagement with one or more small recesses or “detents”  92 ,  93  disposed in an annular recess  91  on the outer surface of the rebound metering cam shaft  90  (illustrated in  FIG. 4 ). The ball  85  and spring  87  are held within the housing assembly  10  by a support member  82 . 
     In one embodiment the ball  85 , the spring  87 , and the detents  92 ,  93  can be used to form an incremental adjuster to control resolution of rotation of the rebound metering cam shaft  90  and thus the axial displacement of the rebound metering rod  24 . As a knob portion of the shaft  90  is turned, there is a noticeable (to the user by “clicking” feel for example) detent engagement and the shaft  90  is held in rotational position by the ball engaged detent. The knob portion of the shaft  90  may be positioned adjacent to the knob  70  for ease of access and operation and is rotatable relative to the housing assembly  10 . The knob portion, in the shown embodiment, is formed integrally with the rebound metering cam shaft  90 , but may be formed as a separate member that is coupled to the shaft in other embodiments. 
     In general, for a given diameter ball and detent depth the number of detent positions at any one axially located circumference is limited by the diameter of the adjuster. In order to increase the number of potential detent positions and hence the adjuster resolution, the shaft  90  is provided with a first row or set of detents  92  and a second row or set of detents  93 , as illustrated in  FIG. 4 . The second row of detents  93  is offset axially from the first row of detents  92 , and is also shifted by half of the rotational angle between same row detents. This pattern creates a “zig-zag” path for the ball  85  to follow as the cam shaft  90  is rotated. The geometry of the detents may be adjusted so that the detents  92 ,  93  intersect and share a portion of their outer boundary. In one embodiment, the ball  85  may move from one detent  92  to an adjacent detent  93  through the intersection formed between the detents  92 ,  93 . 
     As shown in  FIGS. 5 ,  6 ,  7 , and  8 , the detents  92 ,  93  or other suitable recesses/depressions (or protrusions to interface with a cup instead of the shown ball  85 ) are situated at locations circumferentially around the shaft  90 . The detents  92 ,  93  engage with the ball and spring assembly  80  that operates to axially impinge the ball  85  into the detents  92 ,  93  as the detents pass under the ball  85  during rotation of the shaft  90 . As the shaft  90  is rotated, the ball  85  alternatingly plunges into the passing detents  92 ,  93  and is pushed out by compression of the spring  87  as the detent passes by. Subsequently, the ball  85  will plunge into the next sequentially passing detent. Such engagement of the ball  85  with the detents  92 ,  93  creates a “resolution” that can be felt when turning the knob portion of the shaft  90 , whereby the knob portion will tend to come to, and stay in, rest at a ball engaged detent rotational position. 
     It follows from the preceding that the fineness of resolution of the shaft  90  depends on the circumferential density of the detents  92 ,  93  (or protrusions as the case may be). In one embodiment, the ball and spring assembly  80  has some latitude for movement in an axial direction fore to aft, within a recess  88  of the housing assembly  10  (as shown in  FIGS. 5 and 7 ), which is a direction substantially parallel to the axis of the shaft  90 . In one embodiment, the detents  92 ,  93  are positioned in a first circumference  94  about the shaft  90  and also in a second circumference  95  about the shaft  90  such that the first and second circumferences  94 ,  95  are axially close (within a detent radius, for example). The first and second circumferences  94 ,  95  may also coincide with the central axes of the respective row of detents  92 ,  93 . As such, there are two “rows” of detents around the shaft  90 . In one embodiment, the detents  92 ,  93  of the rows may be arranged such that the detents  92 ,  93  as seen on the shaft  90  alternate from one “row” to the next “row” and back again through a shaft rotation. In one embodiment, the ball and spring assembly  80  has latitude to move side to side sufficiently to impress the ball  85  in each alternating detent row as the detents  92 ,  93  pass under the ball  85 . As such, the fineness of shaft  90  resolution is now dependent on the combination of the two rows of detents  92 ,  93 . In one embodiment, there are three detent rows having staggered detents and a ball spring having sufficient latitude to engage all three. In one embodiment the natural “ridge” between adjacent detents is reduced (creating a sort of “detented” zig zag “channel” for example) so that the ball is “guided” in its movement between axially spaced detents. 
     In this manner, the resolution of the shaft  90  formed by the detent  92 ,  93  arrangement provides for a more fine tuned adjustment or movement of the varying outer diameter surface  96  of the shaft  90  to incrementally axially displace and retain the rebound metering rod  24 , which thereby incrementally adjusts the damping rate of the shock absorber  100 . In one embodiment, a shape of the detents  92 ,  93  may be in the form of partial spherical depressions. Other shapes of detents may be used with the embodiments described herein. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be implemented without departing from the scope of the invention, and the scope thereof is determined by the claims that follow.