Abstract:
A method and apparatus for a suspension comprising a spring having a threaded member at a first end for providing axial movement to the spring as the spring is rotated and the threaded member moves relative to a second component. In one embodiment, the system includes a damper for metering fluid through a piston and a rotatable spring member coaxially disposed around the damper and rotatable relative to the damper.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. provisional patent application Ser. No. 61/161,552, filed Mar. 19, 2009, and U.S. provisional patent application Ser. No. 61/161,620, filed Mar. 19, 2009. Each of the aforementioned related patent applications is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to a user-adjustable spring for use in a shock absorber. 
         [0004]    2. Description of the Related Art 
         [0005]    Integrated damper/spring vehicle shock absorbers often include a damper body surrounded by a mechanical spring. The damper often consists of a piston and shaft telescopically mounted in a fluid filled cylinder. The mechanical spring may be a helically wound spring that surrounds the damper body. Various integrated shock absorber configurations are described in U.S. Pat. Nos. 5,044,614; 5,803,443; 5,553,836; and 7,293,764; each of which is herein incorporated, in its entirety, by reference. 
         [0006]    The spring mechanism of many shock absorbers is adjustable so that it can be preset to varying initial states of compression. In that way the shock absorber can be adjusted to accommodate heavier or lighter carried weight, or greater or lesser anticipated impact loads. In motorcycle racing, particularly off-road racing, shock absorbers may be adjusted according to certain rider preferences. 
         [0007]    U.S. Pat. No. 5,044,614 (“the &#39;614 patent”) shows a damper body carrying a thread  42 . A helical spring  18  surrounds the damper body where the two form an integrated shock absorber. The compression in the helical spring  18  may be pre-set by means of a nut  48  and a lock nut  50 . Because the nut  48  and lock nut  50  must be relatively torqued to prevent nut  50  rotation upon final adjustment, the shock absorber must typically be removed from its vehicle in order to allow torquing wrench access. Once the spring  18  is in a desired state of compression, lock nut  50  is rotated, using a wrench, up against nut  48  and tightened in a binding relation therewith. 
         [0008]    The system described in the &#39;614 patent requires that the user be able to access a large amount of the circumference of the shock absorber, and specifically the nut  48  and lock nut  50 , with a wrench (e.g. col. 4, lines 15-17). Unfortunately many shock absorbers, as mounted on a corresponding vehicle, are fairly inaccessible, and have limited surrounding wrench space because of other surrounding vehicle hardware and/or, as in the instant case, a separate damping fluid reservoir or “piggyback.” What is needed is a shock absorber having a spring that can be readily adjusted while the shock absorber is mounted on a vehicle. What is needed is a motorcycle “monoshock” having a spring that can be easily adjusted without removing the shock from the motorcycle. What is needed is a shock absorber having a spring where the state of spring adjustment is constantly indicated and easily visible while the shock is mounted on a vehicle. 
       SUMMARY 
       [0009]    The present invention generally relates to a suspension comprising a spring assembly having a threaded member at a first end for imposing axial movement in the spring as the spring is rotated and thereby rotating the threaded member relative to a second component. In one embodiment, the system includes a damper for metering damping fluid and a rotatable spring member coaxially disposed around the damper and rotatable relative to the damper. In one embodiment an adjustment assembly includes a spring adjustment nut (e.g. follower nut) and clamp with the adjustment nut disposed on a threaded portion of the second component. When the clamp is loosened, the adjustment or “follower” nut rotates with the spring which is rotated by a user and the rotation thereby compresses or decompresses the spring as the nut moves axially (by thread pitch) along the threaded second component. In one embodiment, the clamp includes an indicator that cooperates with markings on the second component to indicate the compression state of the spring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    So that the manner in which the above recited features of the present invention 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. 
           [0011]      FIG. 1  is a perspective view of a shock absorber having a user-adjustable spring. 
           [0012]      FIG. 2  is an exploded view of a follower nut and clamp, and  2 A is a section view thereof. 
           [0013]      FIG. 3  is an enlarged view showing an interface between the clamp, follower nut and spring. 
           [0014]      FIG. 4  is a perspective detailed view of the shock absorber. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIG. 1  shows an embodiment of a reservoir type shock absorber  100 . The shock absorber includes a second component, such as in this embodiment a damper body  120 , with a rod  125  extending therefrom and a reservoir  150  is in fluid (e.g. damping fluid such as hydraulic oil) communication with the damper body  120 . The shock further includes a helical spring  175  annularly disposed about the damper body  120  and captured axially between a bottom clip  180  at a lower end and an adjuster assembly  200  at an upper end. An outer surface of the damper body  120  includes threads  190  that facilitate rotation of nut  210  and corresponding axial movement of the adjuster assembly  200  relative to the body  120 . 
         [0016]    One embodiment of the adjuster assembly  200  is best appreciated with reference to all of the Figures and comprises a follower nut  210  and a clamp  250 . In one embodiment the follower nut  210  includes a pin  215  for fitting into a hole  216  (shown in  FIG. 2 ) in a flange of the nut  210 . Referring to  FIG. 3 , the pin  215  rotationally indexes the follower nut  210  to the spring  175  at an interface  300  between an abrupt end  470  of the wound wire and an upwardly inclined upper surface of the same wound wire in the coil preceding (i.e. directly underneath) the abrupt end  470  of the helical spring  175 . In one embodiment, pin  215  extends axially (i.e. parallel to the longitudinal axis of the shock absorber  100 ) downward from follower nut  210  and extends into the interface space  300 . Due to interference between the pin  215  and the abrupt end  470  of spring  175  in one direction (referring to  FIG. 3 ) and the helical angle of the spring wire in the other direction where the end and the angle combined form an axial recess at an upper end of the spring  175 , rotation of the spring  175  will interfere with the pin (or key or tooth)  215  and impart a rotational force (via the pin  215 ) to the follower nut  210 . Conversely, rotation of the follower nut  210  will carry the pin  215  and a rotational force will be correspondingly transmitted to the spring  175 . In one embodiment (not shown) an upper portion of the spring  175  adjacent the abrupt end  470  is tapered to increase the surface contact between the spring and a lower end of the follower nut  210  (i.e. the spring end is ground “flat”). In one embodiment (not shown) the flattened last coil portion of the upper end of the spring includes an axial hole drilled therein for receiving the portion of pin  215  that protrudes from hole  216 . In one embodiment the upper end of the spring is castellated and the lower surface  212  of the nut  210  is castellated such that the castellations of the nut and the spring are interengageable for rotationally fixing the nut  210  to the spring  175 . In one embodiment, the nut  210  includes a ratcheting pawl set on a lower surface thereof and the spring includes suitable beveled one way castellations on an upper surface thereof (or vice versa) and the spring and the nut are therefore rotationally engaged in one rotational direction only (depending on the sense of the ratchet set) and relatively freely rotatable in the other rotational direction. In one embodiment, the spring  175  is rotatable in relation to the bottom clip  180 . In another embodiment the bottom clip  180  is bearing-mounted (e.g. with a race of ball bearings disposed between a lower end of the spring and an upward facing surface of the bottom clip  180  in axially abutting relation to each) to a shock mount  195  and thereby facilitates easier rotation of the spring  175  relative to the damper body  120  (by reducing the relative apparent coefficient of friction between the bottom clip and the lower end of the spring). In one embodiment, the spring comprises a plurality of springs axially abutted one with another where each of the springs has a different spring rate. In one embodiment, at least one spring of a shock absorber is wound having a compound spring rate. It is worth noting that as the spring  175  is placed in greater states of compression, the friction force between the spring  175  and its axial abutments at the clip  180  and the follower nut  210  are increased. 
         [0017]    While the follower nut  210  is a separate component in some embodiments, it will be understood that the nut can be integral with the spring  175  whereby one end of the spring is therefore effectively threaded to the damper housing and axially adjustable upon rotation of the spring while an opposite end of the spring is axially fixed but rotationally movable relative to the damper body. In one embodiment, the clamp member can also be formed to simply include a threaded member, for instance, that interacts with the damper body to prevent rotation between the threads of the integral spring/nut/clamp and the threaded damper body. In one embodiment, the bottom portion  180  includes a cylindrical member, or body, (not shown) axially and upwardly disposed within and along the spring  175 . In one embodiment the cylindrical member is threaded along an axial exterior length thereof. In one embodiment an adjustment assembly  200  is located between bottom clip or annular “lip”  180  and a lower end of the spring  175 . Much as has been previously described in relation to threads  190  and the nut  210 , in one embodiment the threads  211  on an inner diameter of nut  210  are engaged with threads on an outer diameter of the cylindrical member (not shown). The pin  215  engages a recess  300  at a lower end of the spring  175 . As previously described, rotation of the spring  175  correspondingly rotates the nut  210 , via pin  215 , and the nut  210  translates axially along the cylindrical member thereby increasing or decreasing the compression in the spring  175  depending on the direction of rotation and the directional “sense” of the threads. In one embodiment the cylindrical member (not shown) has an inner diameter that is larger than the outer dimensions of the spring and is disposed axially upward along the shock and outside of the spring. A nut is threaded on an outer diameter thereof and engaged with an end of the spring and the cylinder is threaded on an inner diameter thereof and the nut, cylinder and spring cooperate as principally described herein to facilitate adjustment of compression in the spring. In one embodiment the spring includes an assembly  200  and corresponding threaded sections (e.g.  190 , cylindrical member) at each of its ends. In one embodiment the threads at each end are opposite in “sense” so that rotation of the spring increases or decreases compression in the spring twice as fast as a single threaded end version. In one embodiment threads at one end are of a different pitch than threads at the other end of the spring  175 . 
         [0018]      FIGS. 2 and 2A  show details of embodiments of the clamp  250  and follower nut  210 . In one embodiment the follower nut  210  is cylindrical (with varying diameters along its length) generally with a cut though or split  220 , giving it the form of a “C” ring. The clamp  250  is also in the form of a “C” ring, being generally cylindrical and having its own cut or split  230 . As can be seen in  FIG. 2A , the clamp  250  fits over the follower nut  210 . In one embodiment the clamp  250  is expanded elastically at the split  230  to clear a lip  212  at a smaller-diameter end of the follower nut. Once the clamp  250  has cleared the lip, it is returned to a “relaxed” state surrounding a portion of the nut  210  and is rotationally movable relative thereto. The clamp  250  may then rotate about the follower nut  210  (and the follower nut  110  may rotate within the clamp  250 ) but the clamp  250  is retained axially on the follower nut  210  by lip  212 . In one embodiment a screw  260 , with a suitable washer is inserted into the clamp  250  but not tightened until such time as rotational and axial retention of the follower nut  210  on the damper body  120  (e.g. because spring adjustment is complete) is desired. In one embodiment, the adjuster assembly  200 , with its nut  210  and clamp  250 , is threaded onto threads  190  of body  120 , and is moved axially (e.g. by rotation of the threaded ( 211 ) nut  210  about threads  190 ) until an indicator  255  (best seen in  FIGS. 2 and 4 ) formed on the clamp  250  is located adjacent the reservoir  150 . In one embodiment a curved surface  256  of the indicator  255 , corresponding generally to the curved shape of the reservoir body is aligned with the exterior of the reservoir  150  and the follower nut  210  and clamp  250  may be axially translated further toward a lower end of the shock  100  by rotation of follower nut  210  (while clamp  250  remains aligned with reservoir  150  via indicator  255 ). Tightening the screw  260  “closes” the C-shaped clamp  250  and correspondingly closes the follower nut  210  thereby preventing the follower nut  210  from rotating on the threaded surface  190  of the damper body  120 , and therefore frictionally (e.g. as a clamp) locking the nut  210  to the damper body and thus retaining the user-adjusted compression in the spring  175 . 
         [0019]    In one embodiment the indicator  255  connected on clamp  250 , and rotationally fixed relative to the clamp  250 , serves at least two purposes. Its curved surface  256  conforms to a portion of an exterior of the reservoir  150 , thereby preventing rotation of the clamp  250  during rotation of the spring  175 . As such the orientation of screw  260  is maintained relative to the shock absorber and the vehicle on which the shock absorber is mounted. Correspondingly, the screw  260  is maintained in an accessible location for tightening and loosening to facilitate spring  175  adjustment while the shock absorber remains mounted on the vehicle. Second, the indicator  255  serves to indicate axial compression state of the spring  175  relative to a scale  400  (referring to  FIG. 4 ). 
         [0020]    In one example, the clamp  250  is loosened by inserting an appropriate hex or blade type wrench or screw driver (not shown) through a predetermined shock absorber access space available in the vehicle (vehicle such as a monoshock rear shock motorcycle) and rotating screw  260  counterclockwise (assuming a right hand thread screw  260 ) to loosen the clamp. Once the clamp  250  is loose, the spring  175  can be manually gripped, through the access space, by a user and rotated manually, for example, in one embodiment having right hand threads  190  from the top axial view of the shock absorber, clockwise as viewed from the upper end, to increase compression or pre-load in the spring  175 . In that embodiment rotating the spring  175  counterclockwise as viewed from above reduces pre-load of the spring  175  (or vice versa depending on the sense of threads  190 ). As previously described, such rotation of the spring  175  causes rotation of the follower nut  210  and corresponding axial translation of the follower nut  210  (based on the pitch of the threads  190 ) relative to the damper body  120  and along threads  190 . Axial movement of the follower nut  210 , relative to non-axially moving bottom clip  180 , increases or decreases compression pre-load in spring  175 . In one embodiment, when the desired pre-load is obtained, as indicated by movement of the indicator  255 , which moves axially with the nut  210 , relative to the scale  400 , the clamp  250  is retightened by rotating screw  260  clockwise. It should be noted that the scale  400  may be placed on any suitable and axially static component relative to the follower nut  210 /clamp  250  and the indicator  255  may be structured to “point” appropriately thereto. In one embodiment the numerical markers on the scale  400  are indicative of a percentage of compression preload in the spring. In one embodiment, the scale and indicator are visible from an exterior of an assembled vehicle with the shock absorber having the scale and indictor mounted thereon. In one embodiment, the scale  400  and indicator  255  “pair” comprise a longitudinal wire coil and permanent magnet. Position of the magnet relative to the coil is indicated by a state of current through the coil and can be calibrated to correspond to a state of spring compression. In one embodiment the “scale/indicator” pair comprises a proximity sensor and a datum structure. In one embodiment an electronic “scale/indicator” pair is connected to a transmission circuit having wireless protocol capabilities, such as Garmin&#39;s ANT plus, and shock spring compression data is transmitted in real time or in packets to a user interface/output device such as for example Garmin&#39;s  705  edge GPS enabled computer. In one embodiment the shock absorber is a monoshock and is accessible and visible, while mounted in a functional position, through a limited access space of the monoshock equipped vehicle. 
         [0021]    While the foregoing is directed to certain embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.