Abstract:
A suspension control system that is useful with a snowmobile, ATV, and other recreational vechicles, comprising: a main body defining a shock absorber, a piston disposed within the shock absorber, a remote reservoir, a control valve housing, a control valve, a GMR sensor, and a microprocessor. The piston is located in the shock body and is movable between a first piston position and a second piston position under the force of a load acting on the piston. The opposite ends of the fluid chamber are coupled by a channel in fluid communication, the channel permitting fluid to flow from one side of the shock piston to the other. The control valve is operable to control the flow of the fluid through the channel, the valve being movable from an open position, where fluid movement through the channel is permitted, to a closed position wherein the flow of fluid through the channel is blocked.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to suspension dampers for vehicles such as snowmobiles or all-terrain vehicles (ATV&#39;s), and more particularly to a suspension system that provides a controlled cushioned ride.  
         BACKGROUND OF THE INVENTION  
         [0002]    Vehicles such as snowmobiles and ATV&#39;s are prone to shock and vibration due to varying speed and terrain. A variety of suspension systems have been employed on snowmobiles over the years to compensate for the ruggedness of the terrain. A conventional suspension system for a snowmobile includes a number of shock absorbers, and associated springs for supporting the frame of the snowmobile. Such suspension systems usually are not automatically adjustable. Accordingly, persons of different weights or multiple passengers riding on the same vehicle could result in changes in ride or handling characteristics.  
           [0003]    Although conventional snowmobile suspension systems are unable to automatically adjust on a real time basis, some suspension systems do allow for manual adjustment. In these cases, riders must stop the snowmobile, turn off the engine for safety, and manually adjust the stiffness or tension provided by the shock absorbers of the snowmobile. But adjusting the conventional suspension system on snowmobiles is typically a compromise between varying conditions. For example, if the suspension system is set too hard, the shock performs poorly in trail chatter. If the system is set too soft, the shock may waste energy and bottom out on high speed impacts.  
           [0004]    Accordingly a system capable of continuously adjusting the vehicle&#39;s suspension to optimize performance across various speeds and terrains would be desirable.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention relates to suspension systems to increase rider comfort on a tracked vehicle. Generally, the present invention relates to a shock absorber for snowmobiles that senses both velocity and position for controlling ride characteristics. More specifically, the invention uses giant magnetoresistive (GMR) control technology to automatically adjust the vehicles suspension to optimize performance across various speeds and terrains. The shock controls the suspension in the closed position and allows for free flow of the shock&#39;s fluid in the open position. Free flow allows for no damping of the vehicles suspension, which minimizes the shock resulting from an uneven trail surface.  
           [0006]    The GMR senses the position and velocity of the shock rod. The microprocessor receives the information from the GMR sensor and in turn tells the control valve what to do. The actuator in the control valve receives the control signal and adjusts to regulate the fluid flow through a bypass orifice, which in turn regulates the shock damping. When the shock piston is moving rapidly due to high speed hits, large damping forces are generally desired. Conversely, when the shock piston is moving more slowly, smaller damping forces are desired.  
           [0007]    In one embodiment, an electronic controller and power supply, along with a giant magnetoresistive (GMR) sensor, controls the open or close condition of a bypass valve based on shock rod and piston position and velocity. Accordingly, the shock&#39;s main control piston controls the suspension action. Free flow of the shocks fluid through the control valve allows for damping of the vehicle&#39;s suspension. In one embodiment of this invention, the valve housing, remote reservoir and main body are incorporated into one casting, eliminating the need for dozens of parts and valve assembly.  
           [0008]    A GMR sensor in the shock reads the piston speed and position, and sends data back to a microprocessor. The circuit sends a signal to the control valve, allowing it to open and close in a time as short as milliseconds. The control valve regulates the flow of fluid through the bypass ports, which adjusts the shock damping. The end result is a smoother ride and increased track to ground contact and ski control, providing the user with increased control over changing terrain.  
           [0009]    The sensor system includes a magnet and sensor that work in conjunction with the bypass valve. The sensor is based on the giant magnetoresistive (GMR) effect, which detects the “flux density” of the magnetic field and converts it to a voltage signal. This voltage can indicate the speed and position of the shock piston with extreme precision. Sensor information is then relayed to an electronic control circuit, where a microprocessor uses a control algorithm to translate the voltage to command signals for the control valve.  
           [0010]    The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The figures and the detailed description that follows more particularly exemplify these embodiments. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, wherein like numerals represent like parts throughout several views, in which:  
         [0012]    [0012]FIG. 1 is a side elevational view of a snowmobile with some parts cut away and other parts removed, incorporating the shock absorber of the present invention;  
         [0013]    [0013]FIG. 2 is an isometric view of the shock absorber of the present invention;  
         [0014]    [0014]FIG. 3 is a reverse isometric view of the shock absorber of the present invention;  
         [0015]    [0015]FIG. 4 is an isometric view of an alternative embodiment of the shock absorber of the present invention;  
         [0016]    [0016]FIG. 5 is a reverse isometric view of an alternative embodiment of the shock absorber of the present invention;;  
         [0017]    [0017]FIG. 6 is a side view of the shock absorber of the present invention;  
         [0018]    [0018]FIG. 7 is a cross sectional view of the shock absorber taken along line AA of FIG. 6.  
         [0019]    [0019]FIG. 8 is a side view of an alternative embodiment of the shock absorber of the present invention;  
         [0020]    [0020]FIG. 9 is a top view of an alternative embodiment of the shock absorber of the present invention;  
         [0021]    [0021]FIG. 10 is a cross sectional view of an alternative embodiment of the shock absorber taken along line B-B of FIG. 9.  
         [0022]    [0022]FIG. 11 is an end view of the shock absorber of the present invention.  
         [0023]    [0023]FIG. 12 is a cross sectional view of the shock absorber housing taken along line C-C of FIG. 11.  
         [0024]    [0024]FIG. 13 is an isometric view of the shock absorber housing of the present invention.  
         [0025]    [0025]FIG. 14 is an end view of the shock absorber housing of the present invention.  
         [0026]    [0026]FIG. 15 is a cross sectional view of the shock absorber housing taken along line D-D of FIG. 14.  
         [0027]    [0027]FIG. 16 is a reverse isometric view of the shock absorber housing of the present invention.  
         [0028]    [0028]FIG. 17 is an isometric view of the shock absorber housing of the present invention.  
         [0029]    [0029]FIG. 18 is a reverse side view of the shock absorber housing of the present invention.  
         [0030]    [0030]FIG. 19 is a cross sectional view of the shock absorber housing taken along line F-F of FIG. 18.  
         [0031]    [0031]FIG. 20 is a side view of an alternative embodiment of the shock absorber housing of the present invention.  
         [0032]    [0032]FIG. 21 is a cross sectional view of an alternative embodiment of the shock absorber housing taken along line G-G of FIG. 20.  
         [0033]    [0033]FIG. 22 is a bottom end view of an alternative embodiment of the shock absorber housing of the present invention.  
         [0034]    [0034]FIG. 23 is a cross sectional view of an alternative embodiment of the shock absorber housing taken along line H-H of FIG. 22. 
     
    
       [0035]    While the invention is amenable to various modifications in alternative forms, the specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]    The present invention is believed to be applicable to suspension systems to increase rider comfort on a tracked vehicle or ATV. The electronically controlled active suspension damper of the present invention is particularly advantageous with snowmobiles and ATV&#39;s because a variety of shock-producing surfaces are encountered while riding these vehicles. Generally, low amplitude bumps occur at high frequency while high amplitude bumps occur at a much lower frequency because the size of the bump indicates that the bumps must be spaced farther apart. Large snow drifts are examples of high amplitude, low frequency bumps. A frozen lake with a surface that has frozen unevenly due to high winds is an example of terrain with low amplitude, high frequency bumps. The electronically controlled active suspension damper of the present invention is designed to provide increased rider control in different types of terrain.  
         [0037]    [0037]FIG. 1 depicts a snowmobile with the electronically controlled active suspension damper of the present invention. Snowmobile  10  includes a traction unit  11 , a seat area  13 , a chassis  15 , a steering arrangement  17 , a pair of skis  12  (only one shown), a front suspension  16 , and a rear suspension  18 . Front suspension  16  is fastened to the chassis  15 . A shock absorber  22  is disposed between front suspension  16  and chassis  15  to provide front suspension action. The shock absorber  22  provides both shock absorption and damping, as is described in detail below. Front suspension  16  may have many alternative configurations, or other linkage mechanisms. The same damping concepts discussed herein can be applied to these other configurations.  
         [0038]    Rear suspension  18  is pivotally attached to chassis  15  near traction unit  11 . Rear shock absorber  26  is also attached at one end to chassis  15 . When rear suspension  18  encounters a force, rear shock absorber  26  is compressed such that the track  24  is allowed to move relative to the chassis  15  to dampen shock. Alternative rear suspension systems can be employed with rear shock absorber  26 . An example of such a rear suspension system is found in U.S. Pat. No. 5,664,649, incorporated herein by reference. The same damping concepts discussed herein can also be applied to these other configurations and other devices like ATV&#39;s, for example.  
         [0039]    Referring now to FIGS. 2, 3,  6 , and  11 , the details of shock absorber  22  will now be discussed. Note that while shock absorber  22  refers to the shock absorber used with the front suspension  16  of the snowmobile illustrated in FIG. 1, the same or similar shock absorber can be utilized on the rear suspension  18 . Shock absorber  22  includes a rod  32  extending into a main body  34 . In some embodiments, a spring  36  (shown on FIG. 1) may extend along rod  32  and over a portion of the main body  34 . Spring  36  absorbs shock and provides rebound while rod  32  extends into main body  34  and provides damping as explained below.  
         [0040]    Main body  34  encloses fluid reservoir  38 . Remote reservoir  40  may be contained in the same general casting as main body  34  but it is located outside fluid reservoir  38 . Remote reservoir  40  contains fluid chamber  42 , and channel  43 , shown in FIG. 12. Fluid chamber  42  and remote reservoir  40  are interconnected by channel  43  that enables fluid to flow between fluid chamber  42  and remote reservoir  40 . Alternatively, fluid may move from the fluid reservoir  38  to the fluid chamber  42  through hoses connected to fittings in the housing.  
         [0041]    The end of the main body  34  opposite the rod  32  contains a housing end mount  46  for mounting the end of the shock absorber  22  either to the snowmobile chassis  15  or the front suspension  16 . A rod end mount  48  is provided on the opposite side of the shock absorber  22 . In FIG. 1, the rod end mount  48  is mounted to the chassis while the housing end mount  46  is secured to the front suspension  16 .  
         [0042]    Spring  36  may generally be held on rod  32  and main body  34  with spring stop  50  secured to rod  32  near the end of rod end mount  48  and preload ring  52  at the opposite end of spring  36 . In alternative embodiments, preload ring  52  is threadably engaged on main body  34 . Therefore, by turning preload ring  52 , the preload in spring  36  may be adjusted.  
         [0043]    A valve housing  54  is also provided on shock absorber  22 . Valve housing  54  may be contained in the same general casting as main body  34 . Valve housing  54  holds the control valve  56 . The control valve  56  preferably comprises a solenoid capable of actuating from the open to closed position.  
         [0044]    Microprocessor/GMR sensor controller unit  57  is located on the side of fluid reservoir  38 . Microprocessor/GMR sensor controller unit  57  contains a GMR sensor, which is capable of sensing the velocity and position of the rod  32 . The GMR sensor sends a signal to a microprocessor, which processes the information from the GMR sensor and actuates the control valve  56 . The microprocessor may also be located in the sensor controller unit  57 . Power wire  59  provides electric current to the components in the microprocessor/GMR sensor controller unit  57 .  
         [0045]    Referring to FIG&#39;s.  6  and  7 , fluid reservoir  38  includes an opening at one end through which rod  32  is inserted. A reservoir cap  63  may extend around the rod  32  and be held tightly within the open end of the main body  34  to create an enclosed fluid reservoir  38 . A reservoir seal  65  is also included on the outside of reservoir cap  63 . Reservoir cap  63 , valves, and rod seal  67  reduce the chances of hydraulic fluid escaping from fluid reservoir  38 . O-rings may generally be employed at appropriate locations to ensure adequate sealing. In alternative embodiments, reservoir cap  63  will abut a bottom out bumper  69  held on rod  32  adjacent the spring stop  50  when rod  32  extends all the way into hydraulic reservoir  38 .  
         [0046]    Piston assembly  64  is located on rod  32  opposite rod end mount  48 . Piston assembly  64  includes compression ports that allow fluid to pass from one side of piston assembly  64 , through piston assembly  64 , to the other side of piston assembly  64  as rod  32  moves toward end mount  46 . Piston assembly  64  also includes rebound ports that allow fluid to pass through piston assembly  64  as rod  32  moves away from end mount  46 . The compression ports and rebound ports generally have a very small diameter, which prevent piston assembly  64  from moving rapidly inside fluid reservoir  38 , thereby resulting in a relatively stiff suspension. For this reason, bypass channel  44  is provided, which enables fluid to quickly move from one side of piston assembly  64  to the other side of piston assembly  64  when control valve  56  is in the open position.  
         [0047]    A GMR sensor is provided to detect both the displacement and velocity of the piston assembly  64  relative to the main body  34 . The sensor and control arrangement preferably employed in the present invention includes a magnet  66  secured on the end of the piston assembly  64 , as shown in FIG. 7. The sensor may be secured in the sensor controller unit  57 . The sensor is preferably connected to a circuit board comprised of a microprocessor chip that includes the microprocessor logic to manipulate the control valve  56  based on the signal from the sensor. As the rod  32  moves in response to changing terrain, the magnet  66  moves past the GMR sensor located in the control unit  57 . The GMR sensor detects the velocity and position of the magnet  66 , which corresponds to the velocity and position of the rod  32 . The microprocessor interprets the information from the sensor, which manipulates the control valve  56 .  
         [0048]    When the control valve  56  is in an open position, fluid is allowed to freely move through channel  44  and between the fluid reservoir  38  and the remote reservoir  40 . Alternatively, when the control valve  56  is in a closed position, the fluid cannot freely move between the fluid reservoir  38  and the remote reservoir  40 . The suspension will be much stiffer because the fluid must move through the relatively small compression or rebound ports on piston assembly  64 , rather than channel  44 .  
         [0049]    FIGS.  13 - 19  show various views of the body of shock absorber  22 . In FIG. 15, channel  44  is shown. Channel  44  extends from an opening near housing end mount  46  through valve mount  45 , along the wall of fluid reservoir  38 , to another opening near reservoir cap  60 . Channel  44  enables fluid to quickly pass from one side of piston assembly  64  to the other side of piston assembly  64  when valve  56  is in the open position. Valve mount  45  is disposed in channel  44  so that control valve  56  is capable of obstructing the fluid movement through channel  44  when the control valve  56  is in the closed position.  
         [0050]    When the fluid movement through channel  44  is obstructed, the fluid may move through the compression and rebound valves, thereby providing some shock absorption. The diameter of the compression and rebound valves is generally much smaller than the diameter of the channel  44 . Accordingly, the shock absorber  22  is much stiffer when the control valve  56  is in the closed position. When the control valve  56  is in the open position, fluid is permitted to move through the compression valves in addition to the channel  44 . This provides for much less damping than when the control valve  56  is in the closed position.  
         [0051]    Referring now to FIGS. 4, 5,  8 ,  9  and  10  the details of alternative shock absorber  23  will now be discussed. Note that while shock absorber  23  refers to the shock absorber used with the rear suspension of the snowmobile illustrated in FIG. 1, the same or similar shock absorber can be utilized on either the front or rear suspension of snowmobiles or ATV&#39;s.  
         [0052]    Shock absorber  23  is similar to shock absorber  22  in function and purpose. However, shock absorber  23  varies from shock absorber  22  with respect to the placement of the remote reservoir  40  relative to the valve housing  54 . For example, in FIG. 4, the valve housing  54 , and the control valve  56  are located in the same axis as the remote reservoir  40 . Alternatively, FIGS. 1 and 2 show that the valve housing  54  and the control valve  56  are each located alongside the reservoir  40 .  
         [0053]    Shock absorber  23  includes a rod  32  extending into a main body  34 . A spring may extend along rod  32  and over a portion of the main body  34 . Spring  36  absorbs shock and provides rebound while rod  32  extends into main body  34  and provides damping as explained above.  
         [0054]    Main body  34  encloses fluid reservoir  38 . Remote reservoir  40  may be contained in the same general casting as main body  34  but it is located outside fluid reservoir  38 . Remote reservoir  40  contains fluid chamber  42 , shown in FIGS. 10 and 21. Fluid chamber  42  and remote reservoir  40  are interconnected by channel  44 , shown in FIG. 10. Alternatively, fluid may move from the fluid reservoir  38  to the fluid chamber  42  through hoses connected to fittings in the housing.  
         [0055]    The end of the main body  34  opposite the rod  32  contains a housing end mount  46  for mounting the end of the shock absorber  23  either to the snowmobile chassis  15  or the suspension  18  or  16 . A rod end mount  48  is provided on the opposite side of the shock absorber  23 .  
         [0056]    A valve housing  54  is also provided on shock absorber  23 . Valve housing  54  can be axially aligned with remote reservoir  40  and may be contained in the same general casting as main body  34 . Valve housing  54  holds the control valve  56 . The control valve  56  preferably comprises a solenoid capable of actuating from the open to closed position.  
         [0057]    Microprocessor/GMR sensor controller unit  57  is located on the side of shock absorber  23 , generally between main body  34  and remote reservoir  40 . Microprocessor/GMR sensor controller unit contains the GMR sensor, which is capable of sensing the velocity and position of magnet  66  that is fastened to the end of rod  32 . The GMR sensor sends a signal to the microprocessor, which processes the information from the GMR sensor and actuates the control valve  56 . Power wire  59  provides electric current to the components in the microprocessor/GMR sensor controller unit  57 .  
         [0058]    Fluid reservoir  38  includes an opening at one end through which rod  32  is inserted. A reservoir cap  63  may extend around the rod  32  and be held tightly within the open end of the main body  34  to create an enclosed fluid reservoir  38 . O-rings may generally be employed at appropriate locations to ensure adequate sealing.  
         [0059]    A GMR sensor is provided to detect both the displacement and velocity of rod  32  and the piston assembly  64  relative to the main body  34 . The sensor and control arrangement preferably employed in the present invention includes a magnet  66  secured on the end of the piston assembly  64 , as shown in FIG. 10. A sensor may be secured in the sensor controller unit  57 . The sensor is preferably connected to circuit board comprised of a microprocessor chip that includes the microprocessor logic to manipulate the control valve  56  based on the signal from the sensor. As the rod  32  moves in response to changing terrain, the magnet  66  moves past the GMR sensor located in the control unit  57 . The GMR sensor detects the velocity and position of the magnet  66 , which corresponds to the velocity and position of the rod  32 . The microprocessor interprets the information from the sensor, which manipulates the control valve  56 .  
         [0060]    FIGS.  21 - 23  show various views of the body of shock absorber  23 . In FIG. 21, valve mount  45  is shown. Valve mount  45  is disposed in channel  44  so that control valve  56  is capable of obstructing the fluid movement through channel  44  when the control valve  56  is in the closed position.  
         [0061]    As shown in FIG&#39;s.  7  and  10 , piston assembly  62  contains compression and rebound valves  60 . When the fluid movement through channel  44  is obstructed, the fluid may move through the compression and rebound valves, thereby providing some shock absorption. The diameter of the compression and rebound valves is generally much smaller than the diameter of the channel  44 . Accordingly, the shock absorber  23  is much stiffer when the control valve  56  is in the closed position. When the control valve  56  is in the open position, fluid is permitted to move through the compression valves in addition to the channel  44 . This provides for much less damping than when the control valve  56  is in the closed position.