Abstract:
A suspension system includes multiple shock absorbers and corresponding preload cylinders. A single adjuster mechanism is within reach of a vehicle operator for easily changing a suspension ride height of two of the preload cylinders.

Description:
[0001]     The present invention is a continuation-in-part of U.S. patent application Ser. No. 10/463,162, filed Jun. 17, 2003. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an adjuster mechanism and more particularly to an adjuster mechanism for use in adjusting a spring preload such as for an off road vehicle (ORV) or all terrain vehicle (ATV).  
         [0003]     Suspension systems in vehicles are commonly subjected to varying road conditions. This is especially true in ORVs, ATVs, snowmobiles, and the like. These vehicles may have adjustable suspension systems to accommodate the preferences of the vehicle operator on irregular terrain. Known systems that allow for one remote adjuster for all shock absorbers have been directed toward adjustment of the internal pressure of the shock absorber, as opposed to an external preload cylinder.  
         [0004]     Preload cylinders have been connected to, and are typically concentric with, shock absorbers for adjusting the spring preload of the shock absorber assembly. The preload cylinder may support a suspension spring associated with the shock absorber. Adjustment of the preload cylinder varies the load placed on the suspension springs thus increasing or decreasing the suspension load carrying capacity. A desired ride comfort level, provided by the suspension ride height, varies from operator to operator. For example, the weight of the operator affects the performance of the suspension system. The effect of varying weight is especially noticeable on the performance of suspension systems in smaller vehicles like snowmobiles and ATVs.  
         [0005]     Many systems have the ability to adjust the suspension while the vehicle is in operation by providing an adjustment mechanism within reach of the operator. In one proposed adjustment system for a motorcycle there are two shock absorbers which are adjustable through a single control. This system uses a compressible fluid. The compressible fluid in the prior art system would allow fluid to flow from one shock absorber to another when a force is applied to one side of the vehicle. That is, the compressible fluid will not resist the force.  
         [0006]     Accordingly, it is desirable to provide a suspension adjustment system which allows for equal preload adjustment.  
       SUMMARY OF THE INVENTION  
       [0007]     The suspension system according to the present invention provides a system for making equal adjustments to a plurality of preload cylinders.  
         [0008]     The suspension system includes multiple shock absorbers and corresponding preload cylinders. The height of the preload cylinders is adjustable by a lever attached to an adjuster mechanism. The adjuster mechanism is within reach of a vehicle operator for easily changing the suspension height while the vehicle is in operation. Changes to the position of the adjuster mechanism will correspondingly adjust the position of all the preload cylinders and thus vary the spring preload of a spring associated with the shock absorber.  
         [0009]     As disclosed, there are at least two shock absorbers and preload cylinders connected to an adjuster mechanism. Changes in the adjuster mechanism will affect all preload cylinders equally. Thus, only one adjuster mechanism is needed. The system may be used on front and/or rear shock absorbers.  
         [0010]     The system has incompressible fluid within the adjuster mechanism. The incompressible fluid ensures that a force on one side of the vehicle will be resisted by the suspension on the other side of the vehicle. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:  
         [0012]      FIG. 1  is a general schematic view of the suspension system of the present invention;  
         [0013]      FIG. 2  is a partial cross-sectional view of the shock absorber and preload cylinder of the present invention; and  
         [0014]      FIG. 3  is a side view of an adjuster mechanism of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]      FIG. 1  illustrates a suspension system  10  in an ATV, shown schematically. The suspension system  10  includes a shock absorber  12  mounted between a wheel  14  and a vehicle body  16 . The mounting structure is shown schematically and may be as known. The shock absorber  12  has a preload cylinder  18 . The preload cylinder  18  is mounted between a shock absorber housing  20  and a coil spring  22 .  
         [0016]     The preload cylinder  18 , shown in  FIG. 2 , is arranged about the shock absorber  20 . The shock absorber  20  is as known, including a piston  21  movable within a housing  23 . An outer wall  30  of the preload cylinder  18  is spaced apart from the shock absorber  20  to form an internal chamber  34 . As is known, the spring  22  provides some control over the ride characteristics of the shock absorber  20 . The spring force of the spring  22  can be adjusted to adjust the initial preload force, as known. This adjustment is the function of the preload cylinder  18 . Hydraulic fluid within the preload cylinder  18  adjusts the position of the preload cylinder, which in turn allows the spring to expand, or causes the spring to contract to adjust the preload force, again as known.  
         [0017]     A lower wall  26  of the internal chamber  34  is supported by a dimple  27  extending from the shock absorber housing  20 . The outer wall  30  extends down, past the lower wall  26 . This allows the size of the preload cylinder  18  to be adjusted without allowing fluid leakage and pressure loss to the internal chamber  34 . The upper surface  28  of the preload cylinder  18  supports the coil spring  22 .  
         [0018]     An adjuster mechanism  38  is shown in  FIG. 3 . The adjuster mechanism  38  is located remotely from the preload cylinder  18 . As is shown in  FIG. 1 , adjuster mechanism  38  may be mounted on the handlebars or in some other position within easy reach of the vehicle operator. The adjuster mechanism  38  is moveable between a plurality of positions which correspond to positions of the preload cylinder  18 . The adjuster mechanism  38  is connected to preload cylinders  18  associated with a pair of shock absorbers  20  by a fluid line  40 .  
         [0019]     Adjusting a lever  42  changes the position of the adjuster mechanism  38  resulting in an increase or decrease the amount of fluid that is in the preload cylinder  18 . The adjuster mechanism  38  includes a fluid reservoir  43 . Moving lever  42  will cause a first mechanism arm  45  to pivot about fixed pivot  41 , which in turn causes a second mechanism arm  47  to pivot. As the first and second mechanism arms  45  and  47  pivot, a reservoir piston  49  moves inwardly or outwardly of reservoir  43 . The change in the position of reservoir piston  49  will increase or decrease the amount of hydraulic fluid in the fluid reservoirs  43 . As mentioned, fluid reservoir  43  is fluidly connected to the internal chamber  34  of the preload cylinders  18  by fluid line  40 . Thus, by moving the lever  42 , the relative amount of fluid in the internal chambers  34  can be varied. As the fluid in the internal chambers is varied, the position of wall  30  changes and hence the length of spring  22  changes.  
         [0020]     Because the preload chambers  34  are connected hydraulically by the fluid line  40 , fluid pressure remains constant across both chambers resulting in a balanced preload force between the two chambers. Fluid will transfer from one chamber  34  to the other connected chamber  34  in order to keep pressure equal, and the total fluid volume in both chambers  34  plus the fluid line  40  will remain constant. Therefore the amount of preload cylinder stroke available in the assembly  18  must be limited so as not to allow excessive displacement difference between one side and the other connected assemblies  18 , the amount which depends on the specific vehicle application. In addition, the size of the cross sectional flow area of the fluid line  40  can be designed to control the speed at which the connected chambers  34  can equalize, preventing sudden bumps from offsetting the vehicle.  
         [0021]     A scale  48  is used to designate an appropriate position for lever  42  given a particular load on the suspension system. For example, scale  48  may have detents given in weight increments. Thus, a system operator may adjust the setting to reflect the payload that will be placed on the suspension system. The payload setting may be the passenger&#39;s weight, for example. The adjuster mechanism  38  then makes the appropriate adjustments to reflect the change. The embodiment shown utilizes a lever and scale display. However, it should be known that an electronic control and display may be used as well.  
         [0022]     Of course, a user may determine that a position on the scale higher or lower than the user&#39;s actual weight may be most desirable given the particular ride height level the user would like. However, the scale setting based upon weight would provide that user with the ability to make an intelligent choice to begin the process of selecting the desired position.  
         [0023]     The adjuster mechanism  38  may be attached to two shock absorbers  12 . Alternatively, the system may be used with all of the shock absorbers on the vehicle.  
         [0024]     The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.