Abstract:
An air-bag suspension system for a motorcycle having a motorcycle main frame, fender struts extending outwardly from the main frame, and a swing arm pivotally mounted to the main frame about a pivot axis. The air-bag suspension system includes shock absorber assemblies each having an air-bag. The air in the air-bags is generated by an on-board compressor and released through a solenoid valve. The air-bag suspension system replaces the standard coil spring hydraulic suspension commonly found on motorcycles and provides a greater range of adjustment, remotely controlled, while the motorcycle is in use. The air-bag suspension system accommodates heavier loads than the stock suspension systems when the air-bags are fully inflated; and when deflated completely, provide an aesthetically pleasing stance. The range of wheel travel provided allows the rider to adjust the suspension to provide the smoothest ride coupled with an increased load capacity or adverse road conditions.

Description:
CROSS REFERENCES TO CO-PENDING APPLICATIONS 
   This application is a continuation-in-part (CIP) of Ser. No. 09/753,591 entitled “Air-Bag Suspension System” filed on Jan. 3, 2001, now abandoned both by the same inventor, pending. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention is for an air-bag suspension system for a motorcycle or other vehicle which utilizes an on-board compressor to increase the pressure in the air-bags and a controlled release valve for decreasing the pressure in the air-bags. The air-bag suspension system replaces the standard coil spring hydraulic shock system currently and previously used on most motorcycle rear suspension systems. The air-bag suspension system creates a greater range of wheel travel which allows the user to raise or lower the rear end of the motorcycle remotely and while traveling to accommodate for motorcycle load, rear fender ground clearance, road conditions and desired appearance. 
   The present invention adapts the teachings of the previously filed patent applications, but applies them to motorcycles other than the Harley-Davidson® SOFTAIL® model. The reconfiguration of the SOFTAIL® air-bag suspension system permits use of an air-bag suspension system for use on Harley-Davidson® “FL” models and other motorcycles which use coil spring hydraulic shock absorbers. It is to be understood that the air-bag suspension system is not limited to motorcycles, and may be used on ATVs, automobiles, or other vehicles equipped with coil spring hydraulic suspension systems. 
   2. Description of the Prior Art 
   Prior art in the field of rear motorcycle suspension system often uses a coil spring hydraulic system which is mounted to the rear fender strut of the main frame and the swing arm of a motorcycle. The coil spring hydraulic suspension utilizes an air-assist suspension system which only allows minimal adjustment (approximately 15-35 psi), which provides minimal wheel travel which causes bottoming out, and which requires frequent replacement due to seal and overall shock failure. The coil spring hydraulic shock absorbers also must be manually adjusted with a hand pump when the motorcycle is not in use. The present invention overcomes the shortcomings of the prior art by providing a durable air-bag suspension system which can be remotely engaged causing the rear end of the motorcycle to rise and lower while the motorcycle is being ridden. The air-bag suspension system also provides more wheel travel (3.5 inches) and adjustment capacity (0 psi to 150 psi) than the standard coil spring hydraulic suspension system (0 psi to 35 psi). The air-bag suspension system allows the user to carry significantly more weight than 300-400 pounds, whereas the standard coil spring hydraulic system will bottom out when the motorcycle is loaded with 300-400 pounds. The air-bag suspension system is designed for a fast and easy aftermarket exchange and creates a smoother, more comfortable ride and an increased load capacity than that of the stock coil spring hydraulic suspension system. 
   SUMMARY OF THE INVENTION 
   An air-bag suspension system for a motorcycle having a main frame, a pair of fender struts mounted to the main frame in a parallel fashion, and a swing arm pivotally mounted to the motorcycle main frame about a pivot axis. The air-bag suspension system includes an on-board compressor, a solenoid valve, at least one or two shock absorber assemblies each having an internal air-bag, and a plurality of air hoses and Y-connectors. The swing arm includes a pair of arms which include mounting brackets to accommodate the lower ends of the shock absorber assemblies. The air-bag suspension system allows the rider to remotely raise and lower the rear end of the motorcycle while in use by increasing or decreasing the air in the air-bags and provides a broad range of adjustment to accommodate heavy loads, bottoming-out, road hop and desirable aesthetic characteristics. The air is generated by the on-board compressor and released by the solenoid valve. There is also provided an optional pressure gauge which allows the rider to monitor the amount of air in the air-bags at all times. When properly adjusted, the air-bag suspension system provides a smoother ride with greater wheel travel than that provided by stock suspension systems. 
   One significant aspect and feature of the present invention is an on-board compressor and solenoid valve which control the amount of air in the air-bag suspension system. 
   Another significant aspect and feature of the present invention is increased wheel travel which allows greater adjustment range to create the smoothest ride. 
   Still another significant aspect and feature of the present invention is elastomeric air-bags incorporated into the shock absorber assemblies. 
   Yet another significant aspect and feature of the present invention is an optional pressure gauge which allows constant monitoring of the amount of air in the air-bag suspension system. 
   A further significant aspect and feature of the present invention is greater load capacity than stock suspension. 
   A still further significant aspect and feature of the present invention is elimination of road hop when properly adjusted. 
   Yet another significant aspect and feature of the present invention is the ability to remotely adjust the stiffness\softness of the suspension while the motorcycle is in use without the need for special tools. 
   Having thus described an embodiment of the present invention and mentioned significant aspects and features, it is the principal object of the present invention to provide an adjustable air-bag suspension system to create a smoother ride. 
   One object of the present invention is to provide an air-bag suspension system which allows for more wheel travel and greater range of adjustment. 
   Another object of the present invention is to provide an on-board compressor and solenoid valve to control the amount of air in the air-bag suspension system. 
   Yet another object of the present invention is to provide an air-bag suspension system that prevents bottoming-out when carrying a heavy load. 
   Still another object of the present invention is to provide an easily exchangeable air-bag suspension system to replace the standard coil spring hydraulic system. 
   A further object of the present invention is to provide an air-bag suspension system which allows the rider to adjust the amount of stiffness\softness of the suspension while the motorcycle is in motion. 
   A still further object of the present invention is to provide a means to lower the rear end of the motorcycle as near to the ground as desired for aesthetic purposes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
       FIG. 1  illustrates an isometric view of the air-bag suspension system, the present invention, mounted to a representative motorcycle chassis; 
       FIG. 2  illustrates a cross sectional view of a shock absorber assembly which is fully extended; 
       FIG. 3  illustrates a cross sectional view of a shock absorber assembly at mid-stroke; 
       FIG. 4  illustrates a cross sectional view of a shock absorber assembly which is fully compressed; 
       FIG. 5  illustrates a side view of a motorcycle chassis where the air-bag suspension system is fully extended; 
       FIG. 6  illustrates a side view of a motorcycle chassis where the air-bag suspension system is completely compressed; 
       FIG. 7  is a schematic of the air source and distribution system of the air-bag suspension system; 
       FIG. 8  is an electrical schematic diagram of the air-bag suspension system; and, 
       FIG. 9  is a graph comparing the air-bag suspension system to a stock coil spring hydraulic suspension system and illustrates the range of adjustment allowed by the air-bag suspension system and the stock coil spring hydraulic suspension system. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  illustrates an isometric view of the air-bag suspension system  10 , the present invention, mounted to a representative motorcycle chassis  12 . The chassis  12  is comprised of a main frame  14 , a swing arm assembly  16  which is appropriately mounted to the main frame, and a pair of fender struts  18   a  and  18   b . The swing arm assembly  16  is comprised of swing arm pivot assembly  20  and a swing arm  22  having a pair of arms  24   a  and  24   b . The construction and function of the swing arm assembly  16  is understood by anyone skilled in the art. The air-bag suspension system  10  is comprised of shock absorber assemblies  26   a  and  26   b , an on-board compressor  28 , a solenoid valve  32  (shown in FIGS.  7  and  8 ), a control panel  30  having a pressure gauge  92  and a switch  94 , and a plurality air hoses  58   a - 58   n  and Y-connectors  86 ,  88  and  90 , as illustrated in FIG.  7 . The control panel  30  may be mounted on the handlebars, the gas tank, the main frame  14  or any other appropriate position where the rider can monitor the pressure gauge  92  and actuate switch  94 . The control panel  30  may be separated and the switch  94  and pressure gauge  92  may be mounted in different locations. The compressor  28  and solenoid valve  32  may be mounted to the battery box, the main frame or any other appropriate position. The air hoses  58   a - 58   n  and Y-connectors  86 ,  88  and  90  interconnect the shock absorber assemblies  26   a  and  26   b  with the compressor  28 , solenoid valve  32  and control panel  30 , and are routed and appropriately secured to the motorcycle in such a fashion as to not interfere with the operation of the motorcycle. The shock absorber assemblies  26   a  and  26   b  replace the factory installed coil spring hydraulic shock absorbers, and will be described in detail with reference to  FIGS. 2-4 . The shock absorber assemblies  26   a  and  26   b  are mounted at their upper ends by their fender strut mounts  68  to the fender struts  18   a  and  18   b , respectively, which are secured to the main frame  14 , as illustrated. The lower ends of shock absorber assemblies  26   a  and  26   b  are mounted to mounting brackets  42   a and  42   b  which are incorporated in the arms  24   a  and  24   b  of the swing arm  22  which is pivotally secured to the swing arm pivot assembly  20 . The swing arm pivot assembly  20  is mounted to the main frame  14 , allowing pivotal rotation of arms  24   a  and  24   b  of the swing arm  22  about pivot axis  40 . The range of pivotal rotation will be further described and illustrated in  FIGS. 5-6 . 
     FIG. 2  illustrates a cross-sectional view of shock absorber assembly  26   a  which is fully extended. Now described in detail is the shock absorber assembly  26   a . It is to be understood that shock absorber assembly  26   b  is identical in construction and function to shock absorber assembly  26   a . The shock absorber assembly  26   a  is comprised of an air-bag assembly  43  and a hydraulic assembly  78 . 
   The air-bag assembly  43  is comprised of an air-bag  44  formed of an elastomeric material, a piston  46  having a lower annular flange  48 , a piston clamp  50 , a piston seal  52 , an air hose fitting  56 , an air hose  58   n , an air-bag cap  60  having an upper annular flange  62 , a cap clamp  64 , and a fender strut mount  68 . The air-bag  44  is internally secured to piston  46  at lower annular flange  48  by piston clamp  50 , and air-bag  44  is externally secured to air-bag cap  60  at upper annular flange  62  by cap clamp  64 , creating an extendable and retractable air pocket  66  which communicates with an aperture  72  which extends through fender strut mount  68  which is internally secured to air-bag cap  60 . Air hose fitting  56  is attached to aperture  72  and allows air from air hose  58   n  created by compressor  28  to enter air pocket  66 . The fender strut mount  68  has an internally mounted sealed bearing  70  which accommodates mounting hardware and allows pivotal rotation when secured to fender strut  18   a . There is also provided an optional cover  73  which protects air-bag  44  from punctures and abrasions. The air-bag suspension system  10  will function identically with or without cover  73 . 
   The hydraulic assembly  78  has a body  82  secured to piston  46  and a push rod  80  which constitute a typical shock absorber or hydraulic dampener when combined. The body  82  of hydraulic assembly  78  has an internally mounted swing arm mount  74  with an internally mounted sealed bearing  76  at its lower end which accommodates mounting hardware and allows pivotal rotation about pivot axis  40  ( FIG. 1 ) when secured to arm  24   a  of swing arm  22 . The push rod  80  travels up and down and is controlled by the amount of air in air pocket  66 . Piston seal  52  slidingly engages push rod  80  and prevents air inside air-bag  44  from leaking into or out of air pocket  66 . 
   When the shock absorber assembly  26   a  is fully extended, the rear end of the motorcycle will be in the fully raised position. In the fully raised position, the rider is able to carry a passenger and/or heavy load without bottoming out, maximizing the shock absorber&#39;s capability, and still experience a comfortable ride. 
     FIG. 3  illustrates a cross-sectional view of shock absorber assembly  26   a  at mid-stroke, where all numerals correspond to those previously described. When shock absorber  26   a  is at mid-stroke, the rear suspension is partially extended and the motorcycle rear end will be halfway between the fully raised position ( FIGS. 2 and 5 ) and the fully lowered position (FIGS.  4  and  6 ). In order to reach the mid-stroke position, an onboard solenoid valve  32  (illustrated in  FIGS. 7-8 ) releases air from air bag  44  through air hose  58   n  and air hose fitting  56  and the air exits the air-bag suspension system  10  through solenoid valve  32 . When air is released from air-bag  44 , air-bag  44  deflates and piston  46  travels toward air-bag cap  60 , compressing shock absorber assembly  26   a . In this halfway position, the rider will experience a more cushioned ride than that of the fully extended or fully lowered positions. Cover  73  is not illustrated, and it is to be understood that cover  73  is optional. 
     FIG. 4  illustrates a cross-sectional view of shock absorber assembly  26   a  which is fully compressed, where all numerals correspond to those elements previously described. When shock absorber assembly  26   a  is fully compressed, the rear suspension is compressed and the motorcycle rear end will be in the fully lowered position. 
     FIG. 5  illustrates a side view of a motorcycle chassis  12  where the air-bag suspension system  10  is fully extended. For purposes of brevity and clarity, the only component of the air-bag suspension system  10  illustrated is shock absorber assembly  26   a , and it is to be understood that all components of the air-bag suspension system  10  are required to properly function. A wheel  36  is shown to illustrate the space between wheel  36  and fender strut  18   a  and the position of arm  24   a  of swing arm  22  when the shock absorber assembly  26   a  is fully extended. 
     FIG. 6  illustrates a side view of a motorcycle chassis  12  where the air-bag suspension system  10  is completely compressed. For purposes of brevity and clarity, the only component of the air-bag suspension system  10  illustrated is shock absorber assembly  26   a , and it is to be understood that all components of the air-bag suspension system  10  are required to properly function. Illustrated in particular is the position of wheel  36  and the pivotal movement of swing arm  22  about the pivot axis  40  of the swing arm pivot assembly  20  when shock absorber assembly  26   a  is completely compressed. The position of swing arm assembly  22  when the shock absorber assembly  26   a  is fully extended ( FIGS. 2 and 5 ) is illustrated in dashed lines  38  to show the range of movement the air-bag suspension system  10  allows. 
     FIG. 7  is a schematic of the air source and distribution system  84  of the air-bag suspension system  10 . The air source and distribution system  84  is comprised of a compressor  28 , a plurality of air hoses  58   a - 58   n , a solenoid valve  32 , a check valve  34 , three Y-connectors  86 ,  88  and  90 , an optional pressure gauge  92 , and the shock absorber assemblies  26   a  and  26   b.    
   When the rider would like the air-bag suspension system  10  to expand, air is generated in compressor  28  and flows through air hose  58   a  into check valve  34 , continues through air hose  58   b  into Y-connector  86 , on through air hose  58   d  into the optional Y-connector  88 , into air hose  58   f  and into Y-connector  90 , which equally distributes the air to air hose  58   g  and  58   n , and finally into shock absorbers  26   b  and  26   a , respectively, causing the rear end of the motorcycle to rise. 
   When the rider would like the air-bag suspension system  10  to compress, air is released from shock absorbers  26   b  and  26   a  and flows through air hoses  58   g  and  58   n , through Y-connector  90 , through air hose  58   f  into optional Y-connector  88 , through air hose  58   d  into Y-connector  86 , on through air hose  58   c , and is released through solenoid valve  32 , causing the rear end of the motorcycle to lower. Once the air flows through Y-connector  86 , it flows through both air hoses  58   b  and  58   c , but the air in air hose  58   b  is stopped by check valve  34 , causing the air to flow through Y-connector  86 , air hose  58   c  and out through solenoid valve  32 . 
   When the air-bag suspension system  10  is in use, a constant pressure is maintained within the air-bag suspension system  10 , which allows for the use of an optional pressure gauge  92  which is fed air through air hose  58   e  at Y-connector  88 . The constant pressure allows the rider to monitor the exact pressure in the system at all times. The air-bag suspension system  10  does not require the pressure gauge  92 , which can be omitted if air hose  58   d  is directly connected to Y-connector  90 . The power and control of the air source and distribution system  84  will be described in detail with reference to FIG.  8 . 
     FIG. 8  is an electrical schematic diagram of the air-bag suspension system  10 . The electrical system  102  of the air-bag suspension system  10  is comprised of a compressor  28 , a solenoid valve  32 , a switch  94 , a fuse  96 , a battery  98  and a plurality of wires  100   a - 100   n  interconnecting the electrical system, as shown. 
   The switch  94  engages compressor  28  in one position, causing expansion of the air-bag suspension system  10 , and in the opposite position, switch  94  engages solenoid valve  32 , releasing air and causing compression of the air-bag suspension system  10 . When switch  94  is left in a neutral position, constant pressure is maintained throughout the air-bag suspension system  10 , until switch  94  is activated. 
     FIG. 9  is a graph comparing the air-bag suspension system  10  to a stock coil spring hydraulic suspension system and illustrates the range of adjustment allowed by the air-bag suspension system  10  and the stock coil spring hydraulic suspension system. The area between the triangle line (▴) and the diamond line (♦) is the range of adjustment of a standard coil spring hydraulic suspension system, and the area between the square line (▪) and the circle line (●) is the range of adjustment of the air-bag  10  suspension system  10 . It is apparent that the air-bag suspension system  10  allows the user a greater range of adjustment (0-150 psi) than that of the stock suspension system (0-35 psi) and a greater wheel travel. 
   MODE OF OPERATION 
   With reference to  FIGS. 1-8 , the mode of operation is now described, where all numerals correspond to those elements previously described. When the air-bag suspension system  10  and Switch  94  are in a neutral position (mid-stroke) as described and illustrated in  FIG. 3 , the rider may adjust the rear ride height and suspension stiffness by adding air into or releasing air from the air-bag suspension system  10 . 
   In order to raise the rear end of the motorcycle, switch  94  is engaged in an upward position and thereby actuates compressor  28  which generates air and introduces it into the shock absorber assemblies  26   a  and  26   b  via a plurality of air hoses  58   a - 58   n  and Y-connectors  86 ,  88  and  90 , as described and illustrated in FIG.  7 . It is to be understood that air is also introduced into the optional gauge  92 , if utilized, and allows the rider to monitor the amount of air in the air-bag suspension system  10 . Once air is introduced into the air-bags  44  of the shock absorber assemblies  26   a  and  26   b , the rear end of the motorcycle will rise and accommodate a heavier load, provide more ground clearance, and prevent bottoming-out over rough terrain. 
   In order to lower the rear end of the motorcycle, switch  94  is engaged in a downward position and thereby actuates solenoid valve  32  which releases air from the shock absorber assemblies  26   a  and  26   b  via the plurality of air hoses  58   a - 58   n  and Y-connectors  86 ,  88  and  90 , as described and illustrated in FIG.  7 . It is to be understood that air is also released from the optional gauge  92 , if utilized, and allows the rider to monitor the amount of air in the air-bag suspension system  10 . Once air is released from the air-bags  44  of the air-bag suspension system  10 , the rear end of the motorcycle will lower and provide a custom appearance. An additional benefit of the air-bag suspension system  10  allows the motorcycle to lower to the point where the main frame  14  makes intimate contact with the ground, when all air is released from the air-bags  44 , eliminating the need for a kick stand, if so desired. 
   It is to be understood that rear wheel travel of the air-bag suspension system  10  allows the rider to adjust  10  ride height and suspension stiffness\softness by adjusting the amount of air in the air-bag suspension system  10  between 0-150 psi, as illustrated in  FIG. 9 , creating a range of adjustment not currently available. 
   Various modifications can be made to the present invention without departing from the apparent scope hereof.