Abstract:
A method and apparatus for a damper. The damper comprises a fluid chamber having a piston dividing the chamber into a compression and rebound sides, a reservoir in fluid communication with the compression side of the chamber, and an isolator disposed between the compression side and the reservoir, whereby the isolator obstructs fluid flow between the compression side and the reservoir. In one embodiment, a bypass provides a fluid path between the compression side and the isolator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of and claims the benefit of and claims priority to co-pending U.S. patent application Ser. No. 14/692,401, filed on Apr. 21, 2015, entitled “COMPRESSION ISOLATOR FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOX-0050US.CON, and is hereby incorporated by reference in its entirety. 
         [0002]    The U.S. patent application Ser. No. 14/692,401 is a continuation application of and claims the benefit of and claims priority to co-pending U.S. patent application Ser. No. 13/226,230, filed on Sep. 6, 2011, entitled “COMPRESSION ISOLATOR FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0050USP1, and is hereby incorporated by reference in its entirety. 
         [0003]    The U.S. patent application Ser. No. 13/226,230 claims the benefit of and claims priority to the U.S. Provisional Patent Application No. 61/380,177 filed on Sep. 3, 2010, now expired, entitled “COMPRESSION ISOLATOR FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0050USL, and is hereby incorporated by reference in its entirety. 
         [0004]    The U.S. patent application Ser. No. 13/226,230 is also a continuation-in-part application of and claims the benefit of and claims priority to U.S. patent application Ser. No. 13/175,244, filed on Jul. 1, 2011, now U.S. Pat. No. 8,627,932, entitled “BYPASS FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0047USP1, and is hereby incorporated by reference in its entirety. 
         [0005]    The U.S. Pat. No. 8,627,932 claims the benefit of and claims priority to the U.S. Provisional Patent Application No. 61/361,127 filed on Jul. 2, 2010, now expired, entitled “BYPASS LOCK-OUT VALVE FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0047USL, and is hereby incorporated by reference in its entirety. 
         [0006]    The U.S. patent application Ser. No. 13/226,230 is also a continuation-in-part application of and claims the benefit of and claims priority to U.S. patent application Ser. No. 13/010,697, filed on Jan. 20, 2011, now U.S. Pat. No. 8,857,580 entitled “REMOTELY OPERATED BYPASS FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0043USP1, and is hereby incorporated by reference in its entirety. 
         [0007]    The U.S. Pat. No. 8,857,580 claims the benefit of and claims priority to the U.S. Provisional Patent Application No. 61/296,826 filed on Jan. 20, 2010, now expired, entitled “BYPASS LOCK-OUT VALVE FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0043USL, and is hereby incorporated by reference in its entirety. 
         [0008]    The U.S. patent application Ser. No. 13/226,230 is also a continuation-in-part application of and claims the benefit of and claims priority to U.S. patent application Ser. No. 12/684,072, filed on Jan. 7, 2010, now abandoned, entitled “REMOTELY OPERATED BYPASS FOR A SUSPENSION DAMPER” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0032US, and is hereby incorporated by reference in its entirety. 
         [0009]    The U.S. patent application Ser. No. 12/684,072 claims the benefit of and claims priority to the U.S. Provisional Patent Application No. 61/143,152 filed on Jan. 7, 2009, now expired, entitled “REMOTE BYPASS LOCK-OUT” by John Marking, assigned to the assignee of the present application, having Attorney Docket No. FOXF/0032L, and is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0010]    1. Field of the Invention 
         [0011]    Embodiments of the present invention generally relate to a suspension damper assembly for a vehicle. More specifically, the invention relates to a compression isolator for use with a vehicle damper. 
         [0012]    2. Description of Related Art 
         [0013]    Vehicle suspension systems typically include a spring component or components and a dampening component or components. Typically, mechanical springs, like helical springs are used with some type of viscous fluid-based dampening mechanism and the two are mounted functionally in parallel. 
       SUMMARY OF THE INVENTION 
       [0014]    Embodiments herein generally comprise a fluid chamber having a piston dividing the chamber into a compression and rebound sides, a reservoir in fluid communication with the compression side of the chamber, and an isolator disposed in a fluid flow path between the compression side and the reservoir, whereby the isolator obstructs fluid flow between the compression side and the reservoir. In one embodiment, a bypass provides a fluid path between the compression side and the isolator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    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 and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0016]      FIG. 1  is a section view of a damper with a piston in a first position within a chamber. 
           [0017]      FIG. 2  is a section view of the damper of  FIG. 1 , with the piston in a second position. 
           [0018]      FIG. 3  is a section view of the damper of  FIG. 1 , with the piston in a third position. 
           [0019]      FIG. 4  is a section view of an alternative embodiment of a damper. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]      FIG. 1  is a section view of a damper  200  that is typically used in a vehicle suspension in order to control excessive movement of a spring (not shown). The damper  200  includes a fluid-filled chamber  122  having a piston  202  and rod  19  for reciprocation therein as the damper operates. At each end, the damper  200  is provided with mounting eyes  205 ,  207  for mounting to different parts of the vehicle. The piston  202  is equipped with shims  49 ,  51  that meter fluid through the piston  202  as it moves in a compression or rebound stroke in the cylinder. For example, in  FIG. 1  the piston  202  is shown in a compression stroke as noted by rod  19  movement directional arrow  203 . As it moves towards a far end (e.g.  205 ) of the cylinder, fluid travels from a compression side  120  to a rebound side  125  via shim  49  along a path  48 . In a rebound stroke (not shown) shim  51  is utilized to meter fluid in an opposite direction through the piston  202 . 
         [0021]    In addition to the shimmed paths  49 ,  51  through the piston  202 , fluid can travel between the compression  120  and rebound  125  sides of the chamber by utilizing an annular bypass  38  formed between the chamber  122  and an outer housing  123 . While the bypass  38  utilizes an annular area and is co-axially disposed around the chamber  122  in the embodiment shown, it could comprise any number of designs so long as it provides an alternative fluid path between compression and rebound sides and around the piston  202 . An internal bypass damper is shown and described in U.S. Pat. No. 6,296,092 which is entirely incorporated herein by reference. From the compression side  120  of the chamber, fluid may, in one embodiment, enter the bypass  38  through one of two ports  28 ,  30 . On the rebound side, communication between the chamber and the bypass  38  is through port  24 . The bypass  38  is a convenient way to provide “position sensitive” dampening. For example, on the compression side  120  of the chamber, the ports  28 ,  30  are axially spaced along the wall of the chamber. During a first portion of a compression stroke (shown in  FIG. 1 ), both ports  28 ,  30  are open and a relatively large volume of fluid in the compression side  120  is free to utilize the bypass  38  to avoid the dampening effects of the piston shim  49 . During a second portion of a compression stroke port  28  is closed by passage of the piston  202  and bypass fluid becomes limited to port  30  which results in increased compression damping. 
         [0022]    At an end opposite the rod  19 , the damper  200  includes a reservoir  110  for collecting fluid as the fluid capacity of the chamber decreases due to the volume of the encroaching piston rod  19  during a compression stroke. The reservoir  110  includes a floating piston  14  that acts to transfer pressure between damping fluid on one side and a gas pocket  18  on another side. As fluid enters the reservoir  110 , the floating piston  14  moves (arrow  20 ) to compress the gas pocket and enlarge the volume of the reservoir  110  thereby compensating for the volume of the rod  19 . In a rebound stroke of the piston  202 , the reservoir returns fluid to the chamber  122  by operating in a reverse fashion (e.g. the pressurized gas pocket expands and damping fluid leaves the reservoir). A fill valve  15  permits access to the gas pocket, permitting the pressure in the pocket  18  to be adjusted based upon various conditions and preferences. 
         [0023]      FIG. 1  also shows an embodiment of a compression isolator assembly  5 . The isolator is constructed and arranged to prevent fluid from rapidly acting upon floating piston  14  of the reservoir  110 . Without the isolator  5  a rapid or direct action of the compression damping fluid on the floating piston  14  can cause cavitation wherein a vacuum is created on the rebound side  125  of the chamber and the gas in the gas pocket essentially collapses, causing the damper to cease functioning properly. Cavitation is inhibited by the isolator  5  and an aperture  100  formed in the isolator  5  that adds additional dampening between the compression side and the reservoir in the event of a rapid movement of damping fluid towards the reservoir. Under normal circumstances, the isolator  5  does not create a noticeable effect on the dampening action of the damper. Rather, it is designed to operate only in high velocity compression events, such as a sudden terrain feature like a square edge bump, to prevent rapid compression from suddenly collapsing the nitrogen gas (or other compressible material) in pocket  18  due to a rapidly moving floating piston  14 . 
         [0024]    In one embodiment, the compression isolator  5  seals a far end of the chamber  122  between the compression side  120  and the floating piston  14  of the reservoir  110 , and fluid communication between the chamber and the reservoir is limited to a fluid path  105  through aperture  100 . As shaft  19  moves in a compression stroke, damping fluid from the compression side  120  is compressed against compression isolator  5  and thereby forced back through piston assembly shim  49  (along flow path  48 ) to rebound chamber  125 . During such compression, additional fluid travels from chamber  120  to chamber  125  by exiting aperture  28  or  30 , traveling in annular space  38  (along paths  150 ,  151 ) and entering chamber  125  via aperture  24  (along path  154 ). At the same time, fluid in chamber  125 , that corresponds to the incurring volume of shaft  19 , is displaced from chamber  125  and exits via aperture  24  (along path  155 ) into annular space  38  toward reservoir  110 . 
         [0025]      FIGS. 1, 2 and 3  illustrate operation of the damper components at various stages in a compression stroke of the piston. In each stage, fluid utilizes a path  48  through piston shim  49 . In  FIG. 1 , the piston is at an early stage in the stroke and both ports  28 ,  30  are exposed to the compression side  120  of the chamber and, as illustrated by directional arrows  150 ,  151  fluid is flowing to the rebound chamber utilizing bypass  38  with fluid entering port  24  shown by arrow  154 . Also shown with directional arrows  152 ,  153 ,  155  is fluid flow from the compression side ( 152 ,  153 ) to the reservoir and from the rebound side ( 155 ) to the reservoir. The various (and sometimes opposing) arrows are simply used to illustrate the possible flow of the fluid in a dynamic system where flow direction is dependent upon a number of factors including the position of the piston in the chamber, the design of shim  49  in the piston  202 , the sizes of the ports, and the characteristics of aperture  100  formed in the isolator  5 . 
         [0026]    As the piston  202  continues its movement towards the end of the chamber (as shown in  FIG. 2 ) the piston passes port  28 , effectively reducing by half the volume of fluid that can exit the compression side  120  into the bypass  38  and requiring that volume of fluid to pass through piston shim  49 , along path  48 . As shown in the Figure, port  28  is now open to the rebound side  125  of the chamber permitting fluid flow from the bypass to the rebound side  125  (along  156 ) and also permitting fluid to exit the rebound side  125  (along arrow  157 ) in the direction of the reservoir  110 . 
         [0027]    Finally, as shown in  FIG. 3 , the piston  202  has passed both ports  28  and  30  and the bypass is effectively closed to the entry of fluid from the compression side  120  of the chamber  122 . Instead, all ports,  24 ,  28 , and  30  serve to carry fluid from the rebound side  125  of the chamber to the reservoir  110  as is necessitated by the volume of the encroaching rod  19 . Flow paths from each port towards the reservoir are shown with arrows  155 ,  157  and  158 . Because the bypass is closed, dampening is increased as the piston moves closer to a “bottom-out” position at a far end of the chamber and fluid is increasingly forced through shim  49 .  FIGS. 1-3  illustrate an embodiment with a bypass  38  to provide position-sensitive damping along with cavitation protection provided by the compression isolator  5 . 
         [0028]      FIG. 4  is a section view of a damper  300  having a remote reservoir or “piggyback”  310 . Like the embodiment of  FIGS. 1-3 , the damper includes an isolator  5  and an annular bypass  38  and includes axially disposed ports  24 ,  28 , and  30  that permit varying amounts of fluid bypass depending upon the position of the piston  202  in the chamber  122 . The primary difference in the embodiment of  FIG. 4  is that the reservoir  310 , floating piston  314  and gas pocket  318  are housed in a separate chamber  312  that is connected to the main damper with a fluid hose  301 . In the damper of  FIG. 4 , the piston is shown partway through a compression stroke (as in  FIG. 2 ) with aperture  28  on the rebound side of the piston and the various flow directions illustrated with arrows as in the previous figures. Specifically, fluid is exiting the compression side via port  30  and potentially migrating to both the rebound side (path  150 ) and to the reservoir (path  158 ). Concurrently, fluid is leaving the rebound side and traveling towards the reservoir along paths  155  and  157 . 
         [0029]    In one embodiment a simplified non-bypass type damper includes a compression isolator  5 . In such embodiment (not shown) fluid travels, during a compression stroke, from the compression side of the piston to the rebound side of the piston only via flow such as along  48  through the piston. Fluid displaced by the incursion of rod  19  is pushed (along with pressure exerted due to compression of the compression side) toward the reservoir and floating piston. In such embodiment, the isolator  5  may have an aperture (in lieu of aperture  100  as shown in the Figures) or apertures located near or about a center of the isolator  5  and sized to allow normal damping flow but to restrict sudden large volume flow that may cause cavitation. It will be understood that the isolator can be used without a bypass by simply utilizing a metering device at an end of the chamber opposite the piston rod. 
         [0030]    While the foregoing is directed to 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. For example, the invention is shown in the embodiments as including a bypass that operates with the compression isolator. Similarly, the location and design of the reservoir is variable, as shown in the disclosed embodiments. Such variations are within the scope of the invention and the claims that follow.