Abstract:
A control system for a heavy-duty vehicle such as a dump-type straight truck includes a portable radio frequency transmitter and a radio frequency receiver. The radio frequency receiver is operatively connected to a vehicle device or assembly which performs a function such as operation of the vehicle dump bed or raising and lowering of the vehicle axle/suspension system, so that the function can be controlled from the cab of the vehicle by the radio frequency transmitter, and whereby the function occurs substantially instantaneously due to the use of radio frequency and eliminates the need for a custom hard-wired control system.

Description:
This application claims the benefit of provisional application No. 60/295,117 filed Jun. 1, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to lift assemblies for vehicle axle/suspension systems, and in particular to the means for operating such lift assemblies. More particularly, the invention is directed to a radio frequency system which controls the air springs that lift and lower the axle/suspension system of a heavy-duty vehicle such as a straight truck or a semi-trailer, wherein the use of radio frequency eliminates the need for a relatively expensive and inefficient hard-wired lift assembly control system. 
     2. Background of the Invention 
     Axle/suspension lift assemblies have been used for many years on heavy-duty vehicles such as tractor-trailers or semi-trailers, straight trucks such as dump trucks, and the like. Such heavy-duty vehicles typically include certain ones of their axle/suspension systems which are equipped to be lifted and lowered. For example, after dumping a load, the operator of a dump truck may choose to lift one of the axle/suspension systems to save it from wear and tear, since it is no longer required to support the additional load previously contained in the dump bed. Pneumatic lift air springs typically are utilized to accomplish the lifting operation. The lift air springs are inflated or deflated for raising or lowering, respectively, the axle/suspension system. Conversely, the ride air springs are deflated or inflated when the axle/suspension system is raised or lowered, respectively. 
     Since such heavy-duty vehicles have a variety of other functions that require control, such as operating the dumping function on a dump truck, it can be appreciated that the operator of the vehicle desires to remain in the cab to control these functions, rather than stepping out of the cab each time a function needs to occur, which can be inconvenient and/or dangerous. Thus, a conventional manner of controlling such functions as axle/suspension system raising and lowering has been to install an air control panel in the cab. A pneumatic supply line or conduit typically is run between a compressed air supply tank mounted outside of the cab, through the cab body, and is operatively connected to the control panel. Air feed lines in turn must also be operatively connected to the air controls, passed through the cab body and run to the rear of the vehicle for operative connection to the lift and ride air springs. 
     Although such an arrangement allows for relatively satisfactory pneumatic control of axle/suspension system lift assemblies from the cab by the operator of the vehicle, there are several disadvantages with such prior art control systems. First, long runs of conduit or air lines must be utilized, which is expensive and inefficient. More particularly, utilizing such long runs of air line results in delayed or slow response time of the air springs when a signal is sent from the air control panel in the cab to lift or lower the axle/suspension system. In addition, such a hard-wired system requires a relatively large control panel to be mounted in a very limited space within the vehicle cab. Also, materials in addition to the air lines are required such as mounting hardware and the like, and due to the large number of components, installation of such a pneumatically-controlled system on a straight dump truck can take up to about a day of labor by an installer, and can take even longer on semi-trailer dump-type trucks. 
     Therefore, a need has existed for a more efficient and inexpensive system for controlling axle/suspension system lift assemblies of heavy-duty vehicles. The present invention solves the above-noted problems by utilizing a radio frequency control system for the axle/suspension system lift assembly, which is capable of sending a radio frequency signal from a portable transmitter located in the vehicle cab to a radio frequency receiver mounted adjacent to the axle/suspension system to be lifted. 
     SUMMARY OF THE INVENTION 
     Objectives of the present invention include providing a control system for lift assemblies of vehicle axle/suspension systems, which is capable of controlling the lifting and lowering of the axle/suspension system without the use of large numbers of the components, including substantially long runs of air line. 
     Another objective of the present invention is to provide such a control system which enables faster response time of the controlled lift assembly when compared to response times achieved by prior art control systems. 
     An additional objective of the present invention is to provide such a control system which eliminates the need for mounting of a relatively large control panel within the vehicle cab. 
     A still further objective of the present invention is to provide such a control system which is economical, durable in use, easy to install, maintain, and replace. 
     These objectives and advantages are obtained by a control system for a function of a heavy-duty vehicle, the control system including, a radio frequency transmitter, a radio frequency receiver mounted adjacent to and operatively connected to an assembly which performs the function, so that an operator can actuate the transmitter to send a radio frequency signal to the receiver for controlling the function. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiment of the invention, illustrative of the best mode in which applicants have contemplated applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
     FIG. 1 is a schematic elevational view of a straight dump truck having a prior art hard-wired control system for an axle/suspension system lift assembly mounted thereon; 
     FIG. 2 is a view similar to FIG. 1, but showing the radio frequency control system of the present invention mounted on the dump truck; and 
     FIG. 3 is a schematic view similar to FIG. 2, but showing the radio frequency control system of the present invention mounted on a semi-trailer. 
    
    
     Similar numerals refer to similar parts throughout the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     So that the radio frequency control system of the present invention for axle/suspension system lift assemblies can be best understood, a prior art control system is shown mounted on a dump-type straight truck in FIG.  1  and is described immediately below. 
     A conventional straight truck of the dump-type is indicated generally at  10  in FIG.  1 . Dump truck  10  includes a cab  11  and a dump bed  12 . Straight trucks such as dump truck  10  typically have from about four (4) to about six (6) total axles, with from about one (1) to about three (3) of those axles being equipped to be lifted. It is understood that conventional semi-trailers can have from about two (2) to about eight (8) axles, with from about one (1) to about four (4) of those axles being liftable. Dump truck  10  shown in FIG. 1 has four (4) axles (not shown), and each one of a plurality of tires, represented as  13   a ,  13   b ,  13   c , and  13   d , is attached to the driver&#39;s side end of a respective one of the axles. On truck  10 , only the axle/suspension system to which tire  13   b  is attached is liftable. 
     As represented schematically in FIG. 1, typically two air springs  20  are utilized as part of the lift assembly used to lift an axle/suspension system. The axle/suspension system also includes a pair of ride air springs  21 . A control system  27  for the lift assembly including lift air springs  20  and ride air springs  21 , includes a supply tank  22  which is a source of compressed air for various systems of truck  10 , including the brake systems (not shown) and the lift and ride air springs. Tank  22  typically is mounted on a frame  15  of truck  10 , outside of cab  11 . A conduit  23  is operatively attached to and fluidly communicates with supply tank  22  and a control panel  24  located within cab  11 . Conduit  23  thus is passed through openings (not shown) that must be formed in cab wall  16 . Each one of a pair of air feed lines  25 ,  26  is operatively attached to and fluidly communicates with control panel  24 , and lift air springs  20  and ride air springs  21 , respectively. Thus, each air feed line  25 ,  26  also passes through openings (not shown) formed in cab wall  16 . 
     As can be clearly understood from the above description and FIG. 1, such a hard-wired control system  27  requires relatively long runs of conduit, particularly for air feed lines  25 ,  26 , which is expensive and inefficient. More specifically, it is understood by those skilled in the art that such long runs of air line  25 ,  26  result in delayed or slow response time of lift and ride air springs  20 ,  21 , respectively, when a signal is sent from control panel  24  in cab  11  by the operator to raise or lower the axle/suspension system. Also, air control panel  24  is relatively large and must be mounted in a limited space within cab  11 . Thus, it can be seen that a large number of components are required for prior art control system  27  schematically represented in FIG.  1  and described above, thus driving up cost not only due to the number of parts, including add-on mounting brackets and the like, but also because of the time required for installation, which can be up to about a day of labor by an installer for dump truck  10 , and possibly even longer on dump-type semi-trailers. 
     FIG. 2 shows a schematic representation of radio frequency control system  30  of the present invention. System  30  is shown installed on dump truck  10 , and only the differences between prior art control system  27  and present invention control system  30  will be discussed in detail below. Control system  30  also operates a pair of lift assembly air springs  20  and ride air springs  21 . However, compressed air supply tank  22  is mounted on truck frame  15  adjacent to lift air springs  20  and ride air springs  21 . Thus, a relatively short run of air feed line  31  is operatively attached to and fluidly communicates with supply tank  22  and air springs  20 . Similarly, another relatively short run of air feed line  32  is operatively attached to and fluidly communicates with supply tank  22  and air springs  21 . 
     In accordance with one of the key features of the present invention, a radio frequency receiver  33 , of a type which is well known in the art, is mounted on or adjacent to air supply tank  22 . More specifically, receiver  33  is operatively connected to and controls the various valves (not shown) of the lift assembly, such as by a solenoid which is well-known in the art, which in turn regulate the flow of pressurized air between tank  22  and air springs  20 ,  21 , via feed lines  31 ,  32 , respectively. A relatively small and portable radio frequency transmitter  34  then can be taken into cab  11  by the operator of the truck and is capable of sending a radio frequency signal to radio frequency receiver  33  mounted near or on air tank  22 . More particularly, when it is desired by the operator to inflate or deflate lift air springs  20  and deflate or inflate ride air springs  21 , for raising or lowering, respectively, the respective axle/suspension system of those air springs, a radio frequency signal is sent from transmitter  34  to receiver  33 . Thus, control system  30  of the present invention has many advantages over prior art control system  27 . 
     More particularly, control system  30  of the present invention eliminates penetration of cab wall  16  by an air supply conduit and air feed lines, and eliminates the need for relatively long air feed lines as well as the need for an air supply conduit  23  such as found in prior art control system  27 . Moreover, the relatively short run of air feed lines  31 ,  32  between supply tank  22  and lift and ride air springs  20 ,  21 , respectively, together with the use of radio frequency, results in relatively quick response of the air springs from the time the operator of the vehicle sends a radio frequency signal via portable radio frequency transmitter  34  in cab  11  to radio frequency receiver  33  mounted on air supply tank  22 . Also, such a system having less components is less expensive and can be installed in less than about an hour. Finally, the present invention contemplates that a trailer of a tractor-trailer equipped with radio frequency receiver  33 , could be pulled by any tractor since radio frequency transmitter  34  is portable and is not hard-wired to a particular tractor. Specifically, transmitter  34  could be conveniently moved from tractor to tractor because the frequency of the portable transmitter matches that of the receiver of a particular trailer to be pulled by the tractor. 
     As noted hereinabove, control system  30  of the present invention also can be utilized on other types of heavy-duty vehicles such as semi-trailers, the various types of which are well known to those having ordinary skill in the trucking art. One type of semi-trailer is shown in FIG.  3  and is indicated at  40 . More particularly, semi-trailer  40  is of the type commonly known as a van trailer and includes a tractor  41  and a trailer  42 . Since the components of control system  30  of the present invention as used on semi-trailer  40  are identical to those used on dump truck  10  described hereinabove and shown in the drawings, and are mounted thereon in generally the same manner, the same numerals will be used to indicate the various components of the control system as were used in the description of the system&#39;s use on the dump truck. As was noted hereinabove, there are various types of straight trucks with dump trucks merely being one type of straight truck. Similarly, there also are various types of semi-trailers, with the van-type shown in FIG. 3 being but one type. As also noted hereinabove, conventional semi-trailers typically have from about two (2) to about eight (8) axles, with from about one (1) to about four (4) of those axles being liftable. As shown in FIG. 3, semi-trailer  40  has six (6) axles (not shown), and each one of a plurality of tires, represented as  43   a  through  43   f , is attached to the driver&#39;s side end of a respective one of the axles. On semi-trailer  40 , only the axle/suspension system to which tire  43   d  is attached is liftable. As with dump truck  10  described hereinabove, control system  30  of the present invention also operates a pair of lift assembly air springs  20  and a pair of ride air springs  21 . Compressed air supply tank  22  is mounted on the frame (not shown) of trailer  42  adjacent to lift air springs  20  and ride air springs  21 . Thus, a relatively short run of air feed line  31  is operatively attached to and fluidly communicates with supply tank  22  and lift air springs  20 . Similarly, another relatively short run of air feed line  32  is operatively attached to and fluidly communicates with supply tank  22  and ride air springs  21 . 
     Radio frequency receiver  33  is mounted on or adjacent to air supply tank  22 . As in dump truck  10  described hereinabove, receiver  33  is operatively connected to and controls the various valves (not shown) of the lift assembly, such as by a solenoid, which in turn regulate the flow of pressurized air between tank  22  and air springs  20 ,  21 , via feed lines  31 ,  32  respectively. Portable radio frequency transmitter  34  then can be taken into the cab of tractor  41  by the operator of semi-trailer  40  and is capable of sending a radio frequency signal to radio frequency receiver  33  mounted near or on air tank  22 . When it is desired by the operator to inflate or deflate lift air springs  20  and deflate or inflate ride air springs  21 , for raising or lowering, respectively, the respective axle/suspension system of those air springs, a radio frequency signal is sent from transmitter  34  to receiver  33 . Thus, control system  30  of the present invention, when incorporated into semi-trailer  40 , has the same advantages over prior art control system  27  as described hereinabove for its incorporation into dump truck  10 . Additional advantages unique to the application of control system  30  of the present invention in semi-trailers already have been described hereinabove. 
     It is understood that radio frequency control system  30  of the present invention could be adapted to perform other control functions on heavy-duty vehicles such as dumping operations, without affecting the overall concept of the present invention. 
     Accordingly, the radio frequency control system for axle/suspension system lift assemblies is simplified, provides an effective, safe, inexpensive, and efficient system which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior axle/suspension lift assembly control systems and solves problems and obtains new results in the art. 
     In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
     Having now described the features, discoveries and principles of the invention, the manner in which the improved radio frequency control system for axle/suspension system lift assemblies is constructed, arranged and used, the characteristics of the construction and arrangement, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations are set forth in the appended claims.