Abstract:
A drive line apparatus has a pair of tubular shafts configured to fit telescopically. The outer shaft has internal splines and the inner shaft has outer splines so that the shafts rotate in unison. Each of the outer and inner shaft has one partially closed end for coupling to a universal joint, wherein the joint connected to the partially closed end of the inner shaft is disposed within the inner shaft for further reducing the length of the drive line apparatus.

Description:
[0001]    This application is a continuation of U.S. patent application Ser. No. 09/814,541 filed Mar. 22, 2001 which claims the benefit of U.S. Provisional Application No. 60/191,162 filed Mar. 22, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to a drive line apparatus for use where there is limited space between a driving member and a driven member.  
         BACKGROUND OF THE INVENTION  
         [0003]    The drive line shaft connects the transmission output to the differential at the rear wheel on rear drive vehicles. The rotary motion of the transmission output shaft is carried to the differential and from there to the wheel. The drive line shaft must change in length and angle as the wheels move up and down. To allow for these two variations, two or more universal joints and a slip joint are required. The universal joint accommodates a change in the drive angle. The slip joint accommodates a change in the length of the drive line.  
           [0004]    In the conventional drive line shaft, the slip joint has outside splines on one shaft and matching internal splines on a mating hollow shaft. The splines cause the two shafts to rotate together and to permit the two to move endwise in relation to each other. This allows changes in the length of the propeller shaft as the rear axles move toward or away from the vehicle frame.  
           [0005]    Some vehicles, such as busses, have the engine mounted at the rear. Due to the limited space available, short shafts and universal joints carry the engine power to the rear wheels. It would be desirable to provide the shortest transmission shaft possible without sacrificing the strength of the shaft to support bearing stresses.  
         SUMMARY OF THE INVENTION  
         [0006]    In one aspect of the invention, a drive line apparatus is provided for connection between an output portion of a driving member and an input portion of a driven member wherein the output portion and input portion are each connectible to a universal joint, and the drive line apparatus includes an outer hollow shaft connectible to a universal joint and an inner hollow shaft connectible to another universal joint wherein the outer and inner hollow shafts are telescopically connected so that at least a portion of the inner hollow shaft is disposed within the outer shaft and at least a portion of the universal joint connectible to the inner shaft is disposable within the inner hollow shaft to minimize the total length of the drive line apparatus.  
           [0007]    In another aspect of the invention, a drive line apparatus is provided for connection between an output portion of the driving member and an input portion on the driven member wherein the drive line apparatus includes an outer hollow shaft having at least one open end and an inner hollow shaft having at least one open end. The drive line apparatus further includes means for rotating the inner hollow shaft in unison with the outer hollow shaft. The drive line apparatus further includes means for connecting either the inner or outer hollow shaft to the output portion of the driving member and means for connecting the other of the inner or outer hollow shaft to the input portion of the driven member, wherein at least a portion of the connection means to the inner hollow shaft is disposed within the inner hollow member. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:  
         [0009]    [0009]FIG. 1 is a perspective view of a shaft coupling incorporating the present invention;  
         [0010]    [0010]FIG. 2 is a cross sectional view of the shaft coupling in FIG. 1 showing an outer shaft member and inner shaft member of the shaft coupling;  
         [0011]    [0011]FIG. 3 is an exploded view of the shaft coupling showing the outer shaft member connected to a driving member and the inner shaft member connected to a driven member; and  
         [0012]    [0012]FIG. 4 is an exploded view of the shaft coupling reversed showing the inner shaft member connected to the driving member and the outer shaft member connected to the driven member.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring now to FIGS.  1 - 4 , the drive line shaft  10  of the present invention includes a first yoke support  12 , a first and second universal joint  14 ,  16 , a second yoke support  24  and an improved shaft coupling  18  including an outer shaft member  20  and an inner shaft member  22 . These components of the drive line apparatus  10  are all interconnected such that the distance between a driving member and a driven member, such as a transmission and differential or axle assembly, is maintained to a minimum.  
         [0014]    The first and second yoke supports  12 ,  24 , and the first and second universal joints  14 ,  16  are conventional devices currently used in the industry. Although many configurations are available for these devices, the Figures show just one example of devices rigidly connected to the output shaft of a driving unit, such as an engine or transmission and devices rigidly connected to the input shaft of a driven unit, such as a generator, transmission, or transfer box.  
         [0015]    The shaft coupling  18  includes an outer shaft member  20  and an inner shaft member  22 . Each of the outer and inner shaft members  20 ,  22  respectively, have a hollow interior. The outer shaft member  20  has an interior dimension for receiving at least a portion of the inner shaft member therein so that the outer and inner shaft members are telescopically connected and can have a common longitudinally extending rotational axis. The inner shaft member  22  has an interior dimension for receiving at least a portion of one of the universal joints  12 ,  14  therein. The dimensions of the outer and inner shaft members  20 ,  22  respectively are further dependent on the load and axial movement required for the application. In general, the outer and inner shaft members  20 ,  22 , respectively, have a larger inner radius or areas than conventional drive line shafts.  
         [0016]    Each of the outer and inner shaft members  20 ,  22  respectively have means for rigid connection to one of the universal joints  14 ,  16 . The means for rigid connection to one of the universal joints is positioned on each of the outer and inner shaft members  20 ,  22  to minimize the space between the first and second universal joints  12 ,  14  while allowing for relative axial movement between the outer and inner shaft members. FIG. 3 shows one example of means for rigid connection wherein each of the outer and inner shaft members  20 ,  22  have one flanged end. The flanged ends  21  and  23  of the outer and inner shaft members  20 ,  22  respectfully provide a surface area and mounting apertures for connection to the corresponding universal joint  14  and  16 . To minimize the space between the first and second universal joints  14  and  16 , the flanged ends  21  and  23  are oriented in the same direction for both outer and inner shaft members  20  and  22 . In other words, the outer surfaces of the flanged ends  21 ,  23  of the outer shaft member  20  and inner shaft member  22 , respectively, are oriented in the same longitudinal direction such that the outer surfaces of flanged ends  21 ,  23  are both facing either the driving member or driven member as best seen in FIG. 3.  
         [0017]    The first universal joint  14  is provided for connection to the first yoke support  12  and adjacent components. The first universal joint  14  connects the outer shaft member  20  to the driving member (FIG. 3) or to the driven member (FIG. 4) via the first yoke support  12 .  
         [0018]    The second universal joint  16  can have the same configuration as the first universal joint  14 . The second universal joint  16  connects the inner shaft member  22  to the driven member (FIG. 3) or to the driving member (FIG. 4) via the second yoke support  24 . The yoke and universal joints shown in the Figures are only one example. Other configurations of coupling joints are known in the art.  
         [0019]    In the illustrated embodiment, simultaneous rotation of the inner and outer shaft members is provided by splined surfaces. As seen in FIGS. 3 and 4 the inner peripheral wall of the outer shaft member  20  is splined, and an outer peripheral surface of the inner shaft member  22  is splined. The inner shaft member has an overall diameter slightly greater than the inner diameter of the outer shaft member  20  so that the outer splined peripheral surface of the inner shaft member  22  can be received within the inner diameter of the outer shaft member  20 , while the splined surface of the outer shaft member  20  matingly mesh with the splined surface of the inner shaft member  22 . As a result, the inner shaft member  22  rotates in unison with the outer shaft member  20 .  
         [0020]    The splined inner surface of the outer shaft member  20  and the splined outer surface of the inner shaft member  22  causes the two shaft members to rotate together and also permits the two shafts  20 ,  22  to move axially or endwise in relation to each other. This configuration allows changes in the length of the shaft as the rear axles move toward or away from the vehicle frame, as used in one application. The shaft coupling  18  replaces the tubular slip shafts of the prior art and allows the pair of universal joints  14 ,  16  to be positioned closer to each other by having the connection to second universal joint  16  of inner shaft member  22  moved toward the connection to the first universal joint  14  of the outer shaft member  20 . This invention provides an advantage over the tubular slip joints of the prior art in that at least a portion of the universal joints can be encompassed within the shaft coupling  18  to minimize space required for the drive line. As seen in FIG. 2, the configuration of the preferred embodiment provides universal joint  16  to be positioned entirely within the inner shaft member  22 .  
         [0021]    Although the shaft coupling  18  has been described and shown as a cylindrical and splined device, it is apparent that other configurations are available for the shaft coupling  18 . For example, the outer and inner hollow members forming the shaft coupling can be other geometric configurations. The shaft may be any three, four, or other multi-sided shaft. The inner and outer hollow members forming the shaft will have complementary surfaces causing the inner and outer hollow members to rotate in unison.  
         [0022]    Further, the connectors of the shaft coupling to the output of the driving member and to the input of the driven member can vary from the illustrated embodiment. Other types of universal joints, such as a simple universal joint or a two-yoke-and-spider universal joint, are conventional. The inner and outer hollow shaft members  22 ,  20  can also include portions of the universal joint integral with the shaft members  22 ,  20  for connection directly to the yokes  12 ,  24 .  
         [0023]    Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.