Abstract:
The present invention provides a level controlling device for an air suspension system of a vehicle. The leveling of a vehicle is automatically controlled by a bellows mounted with a cam for increasing or decreasing the distance between the body and the axle of the vehicle in response to a changing state of the air spring.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to air springs for a vehicle. More particularly, the present invention relates to an air spring level-controlling device for a vehicle that maintains the vehicle height at a constant level.  
         BACKGROUND OF THE INVENTION  
         [0002]    Conventional level controlling devices for maintaining the height of vehicles that use air suspension systems comprise an air spring mounted between a vehicle body and an axle. A leveling valve, that supplies compressed air into or discharges the compressed air from the air spring, maintains the air pressure inside the air spring. The valve supplies or discharges compressed air depending on the relative deviation of the vehicle body and the vehicle axle.  
           [0003]    In use, when the distance between the axle and the vehicle body is reduced the leveling valve is prompted to supply compressed air to the air spring, thereby lengthening the distance between the axle and the body and restoring the level position of the vehicle. However, when the distance between the axle and the vehicle body is extended the leveling valve is prompted to discharge compressed air from the air spring, thereby reducing the distance between the vehicle body and the axle in an attempt to level the vehicle.  
           [0004]    There are several drawbacks with the conventional system. First, the conventional air spring suspension systems require many separate components. There is a link, leveling valve, air compressor and air tank. This increases the cost of vehicles because of the cost of these components. Furthermore, these components require a substantial amount of space. Another drawback is that the more components a system encompasses, the more likely the system is to fail or break down.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides a level control device for an air suspension of a vehicle, which comprises a bellows mounted in series with an air spring between a vehicle body and a vehicle axle. A cam is rotatably mounted inside the bellows to vary the length of the bellows in response to the rotation of the bellows. A pulley is rotatably mounted inside the air spring with a detecting chain is fixed to one end of the air spring and hitched at the pulley. Furthermore, there is a flexible member connected in series to one end of the detecting chain and secured at the other end to the air spring. Also, a rotation synchronizing means is included for allowing the rotating state of the cam and the pulley to be mutually transmitted. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    For fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which:  
         [0007]    [0007]FIG. 1 is a schematic structural drawing illustrating an embodiment of a level control device for an air suspension of a vehicle according to an embodiment of the present invention; and  
         [0008]    [0008]FIGS. 2 and 3 are schematic drawings illustrating a comparison of the operational states of the level control device shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0009]    As shown in FIG. 1, an air spring (A) and a bellows  1  are mounted in series between a vehicle body (B) and a vehicle axle (S). The air spring (A) is disposed therein with a pulley  3 , a detecting chain  5 , and a flexible member  7 . The bellows  1  is formed with a rotatably mounted cam  9  that changes the length of the bellows  1  in response to the rotating state of the cam  9 . The pulley  3  is rotatably fixed within the air spring (A) via a rotating axle  3 - 1 . The detecting chain  5  and the flexible member  7  are connected in series. The detecting chain  5  is mounted around the pulley  3  and attached to the vehicle axle (S) on one end. Similarly, the vehicle axle (S) is also attached to one end of the flexible member  7 .  
         [0010]    The bellows  1  is formed at upper and lower sides with a cam contact plate  11 . Preferably the cam contact plate  11  is made of high strength durable material, and especially at a contact portion where the cam  9  contacts the cam contact plate  11 . It is preferred that the cam  9  is formed in an oblong shape and the center is rotatably fixed at the middle section of the bellows  1  by a rotating axle  9 - 1 .  
         [0011]    There is a rotation synchronizing means, mounted between the cam  9  and the pulley  3  to allow the rotation to be transmitted therebetween. The rotation synchronizing means includes a cam pulley  13  connected to the cam  9  for integral rotation. Also included is a synchronizing pulley  15  that is rotatably connected to the pulley  3  via a concentric axle and a synchronizing chain  17  for connecting the cam pulley  13  with the synchronizing pulley  15 .  
         [0012]    In use, when a vehicle axle maintains a standard state, not ascended nor descended relative to the vehicle body, the oval cam  9  is diagonally positioned within the bellows  1  at a long axis, as shown in the left drawing of FIG. 2. It is preferable that the cam  9  forms approximately a 45-degree angle relative to the lengthwise direction of the bellows  1 . Thus, when the vehicle axle (S) is raised relative to the vehicle body (B), the air spring (A) absorbs the deviation in the distance between the vehicle body (B) and the vehicle axle (S). Therefore, the air spring (A) is shortened, as illustrated in the center drawing of FIG. 2. As a result, the distance from the rotating axle ( 3 - 1 ) to the vehicle axle (S) is shortened and, as such, tension on the detecting chain  5  is initially lost. The flexible member  7  then shortens, taking the slack out of the detecting chain  5  and causing the pulley to rotate in the clockwise direction. This rotates the cam  9  in a clockwise direction, which extends the distance between the vehicle axle (S) and the vehicle body (B).  
         [0013]    [0013]FIG. 3 shows a state where the distance between the vehicle axle (S) and the vehicle body (B) is increased. As shown in the left drawing in FIG. 3, when the distance between the vehicle body (B) and the vehicle axle (S) is expanded from the standard state, the air spring (A) is expanded. The air spring (A) lengthens between the pulley  3  and the position where the detecting chain  5  and the flexible member  7  secure to the vehicle axle (S). As a result, the flexible member  7  is elongated. This prompts the detecting chain  5  to rotate the pulley  3  counterclockwise. The counterclockwise turning effect of the pulley  3  is transmitted to the cam  9  via the synchronizing pulley  15 , the synchronizing chain  17 , and the cam pulley  13 . The cam  9  is then rotated, as illustrated in FIG. 3, to lessen the distance between the vehicle body (B) and the vehicle axle (S), thereby enabling the vehicle to maintain a level position.  
         [0014]    The foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.