Abstract:
An illustrative embodiment includes a propshaft system including a first constant velocity joint generally defining a first axis and having an inner first race, an outer first race, and a first grease cover mated to the outer first race. The propshaft system also includes a first flange having a first flange mating surface and a first flange contour surface. The propshaft system also includes a second constant velocity joint generally defining a second axis and having an inner second race, an outer second race, and a second grease cover mated to the outer second race. The second grease cover is defined, at least in part, by a second grease cover flange surface and a second grease cover contour surface. The propshaft system additionally includes a propshaft portion extending at least partially between the first connection apparatus and the second connection apparatus. The second grease cover contour surface will interfere with the first flange contour surface to provide a visual notification of incorrect orientation of the propshaft portion within the propshaft system.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 10/841,089, filed May 6, 2004, which is incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention generally relates to a power transfer system for a motor vehicle, and more particularly, relates to an improved propeller shaft having an in-vehicle installation error proofing apparatus and method to encourage proper installation of the propeller shaft in the vehicle drive line.  
       BACKGROUND  
       [0003]     There are generally four main types of automotive drive line systems. More specifically, there exists a full time front wheel drive system, a full time rear wheel drive system, a part time four wheel drive system, and an all wheel drive system. Most commonly, the systems are distinguished by the delivery of power to different combinations of drive wheels, i.e., front drive wheels, rear drive wheels, or some combination thereof. In addition to delivering power to a particular combination of drive wheels, most drive systems permit the respectively driven wheels to rotate at different speeds. For example, the outside wheels must rotate faster than the inside drive wheels, and the front drive wheels must normally rotate faster than the rear wheels.  
         [0004]     Drive line systems also include one or more Cardan (universal) and constant velocity joints (CVJ). Cardan joints are the most basic and common type joint used for example, in prop shafts. Although highly durable, Cardan joints are typically not suited for applications with high angles (e.g., greater than 2 degrees) because of their inability to accommodate constant velocity rotary motion. Constant velocity joints, in contrast, are well known in the art and are employed where transmission of a constant velocity rotary motion is desired or required. For example, a tripod joint is characterized by a bell shaped outer race (housing) disposed around an inner spider joint which travels in channels formed in the outer race. This spider shape cross section of the inner joint is descriptive of the three equal spaced arms extending therefrom which travel on the tracks of the outer joint. Part spherical rollers are featured on each arm.  
         [0005]     One type of constant velocity universal joint is a plunging tripod type, characterized by the performance of end motion in the joint. Plunging tripod joints are currently the most widely used in-board (transmission side) joint in front wheel drive wheels, and particularly in the prop shafts found in rear wheel drive, all wheel drive and four wheel drive vehicles. A common feature of tripod universal joints is their plunging or end motion character. Plunging tripod universal joints allow the interconnection shafts to change length during operation without the use of splines which provoke significant reaction forces thereby resulting in a source of vibration and noise. Other common types of constant velocity joints are the plunging VL or cross groove type joint which consists of an outer race and inner race drivably connected through balls located in circumferentially spaced straight or helical grooves alternately inclined relative to a rotational axis. A high speed fixed joint is another type of constant velocity well known in the art and used where transmission of high speed is required. The disc style constant velocity fixed joint is another type of joint known in the prior art. This joint has an outer joint member open on both ends and a cage is assembled from the end opposite the end towards which the cage is urged by the ball expulsion forces under articulated load conditions. The prior art also includes a mono block constant velocity fixed joint also known as a mono block high speed fixed joint. The outer joint part is a bell shaped member having a closed end.  
         [0006]     Drive line systems also include one or more ball spline joints which include a plurality of balls enclosed within a cage to permit rotation around inner and outer respective races. Like constant velocity joints, ball spline joints are adapted to accommodate plunge in the axial direction, i.e., end wise movement. However, unlike constant velocity joints, ball spline joints do not permit articulation at angle.  
         [0007]     A typical drive line system incorporates one or more of the above joints in an all wheel drive or traditional four wheel drive system. In an all wheel drive systems, such joints are used to connect a pair of propeller shafts to a power take off unit and a rear driveline module, respectively. These propeller shafts function to transfer torque to the rear axle in rear wheel and all wheel drive vehicles. Similarly, in a traditional four wheel drive system, such joints are used to connect a propeller shaft between a transfer case and a front axle.  
         [0008]     In the prior art there have been problems with the insertion and installation of a propeller shaft having a high speed fixed joint on one end and a VL plunging joint on the opposite end. The problem occurs when the shaft is installed into the vehicle backwards because both the high speed fixed joint and the VL plunging joint have the same outer diameter and bolt pattern (PCD). If the shaft is installed in the vehicle backwards, it may lead to damage of the VL plunging joint or the high speed fixed joint. Furthermore, the driveline system will not operate as designed if the prop shaft is installed backwards (incorrectly orientated).  
         [0009]     Therefore, there is a need in the art to provide a propeller shaft having an in vehicle installation error proofing method to insure that the prop shafts are installed in the correctly aligned position within the driveline of the automotive vehicle. There also is a need in the art for an improved cover, including a mechanical stop to ensure proper installation of the prop shaft within the driveline of the automotive vehicle  
       SUMMARY  
       [0010]     An illustrative embodiment includes a propshaft system including a first constant velocity joint generally defining a first axis and having an inner first race, an outer first race, and a first grease cover mated to the outer first race. The first grease cover is defined, at least in part, by a first grease cover flange surface and a first grease cover contour surface. The propshaft system also includes a first flange having a first flange mating surface and a first flange contour surface. The first flange is selectively coupled to the first constant velocity joint such that the first flange mating surface is in contact with the first grease cover flange surface, and the first flange contour surface is directly adjacent the first grease cover contour surface. The first constant velocity joint and the first flange at least partially define a first connection apparatus. The propshaft system also includes a second constant velocity joint generally defining a second axis and having an inner second race, an outer second race, and a second grease cover mated to the outer second race. The second grease cover is defined, at least in part, by a second grease cover flange surface and a second grease cover contour surface. The propshaft system further includes a second flange having a second flange mating surface and a second cover contour surface. The second flange is selectively coupled to the second constant velocity joint such that the second flange mating surface is in contact with the second grease cover flange surface, and the second cover contour surface is directly adjacent the second grease cover contour surface. The second constant velocity joint and the second flange at least partially define a second connection apparatus. The propshaft system additionally includes a propshaft portion extending at least partially between the first connection apparatus and the second connection apparatus. The second grease cover contour surface will interfere with the first flange contour surface to provide a visual notification of incorrect orientation of the propshaft portion within the propshaft system. 
     
    
     BREIF DESCRIPTION OF THE DRAWINGS  
       [0011]     Referring now to the drawings, preferred illustrative embodiments are shown in detail. Although the drawings represent some embodiments, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present invention. Further, the embodiments set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description.  
         [0012]      FIG. 1  is a bottom view of a vehicle according to an embodiment.  
         [0013]      FIG. 2  is a perspective view of a drive system according to an embodiment.  
         [0014]      FIG. 3  is a perspective view of a prop shaft according to an embodiment.  
         [0015]      FIG. 4  is a partial sectional view of a prop shaft according to an embodiment.  
         [0016]      FIG. 5  is a partial sectional view of the prop shaft of  FIG. 4  in an undesired configuration, or incorrect orientation.  
         [0017]      FIG. 6  is a partial sectional view of a prop shaft according to an embodiment.  
         [0018]      FIG. 7  is a partial sectional view of a portion of the prop shaft of  FIG. 4 .  
         [0019]      FIG. 8  is a partial sectional view of a portion of a prop shaft according to an embodiment.  
         [0020]      FIG. 9  is a partial sectional view of a portion of the prop shaft of  FIG. 8  in an undesired configuration.  
         [0021]      FIG. 10  is a flow chart showing a methodology of installation according to an embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0022]      FIG. 1  illustrates a motor vehicle  10 . Motor vehicle  10  includes an operative wheel drive system  12 . The drive system  12  includes a pair of front half shaft assemblies  14 ,  16 . The front half shaft assemblies  14 ,  16  are connected to a front differential  18 . Connected to front differential  18  is a power take off unit  20 . The power take off unit  20  is operatively connected to a high speed fixed joint  22 . Operatively connected to the high speed fixed joint  22  is a front prop shaft, or front propeller shaft assembly,  24 . The front propshaft  24  has a first end FE and a second end SE. Operatively connected to front prop shaft assembly  24  is a VL style plunging constant velocity joint designated as reference numeral  26 . Connected to the VL style constant velocity joint  26  is a rear prop shaft assembly  28 . The rear prop shaft assembly  28  is connected on one end to a Cardan joint assembly (not numbered). The Cardan joint assembly may be operatively connected to a speed sensing torque device  30 . The speed sensing torque transfer device  36  is operatively connected to a rear differential assembly  32 . A pair of rear half shaft assemblies  34 ,  36  are each connected to the rear differential assembly  32 . As shown in  FIG. 2 , attached to the rear differential assembly  32 , is a torque arm  38 . The torque arm  38  is further connected to a torque arm mount  40 , which is attached to the body of vehicle  10 .  
         [0023]     The front half shaft assemblies  14 ,  16  are comprised of fixed constant velocity joints  42 , and an interconnecting shaft in a plunging style constant velocity joint  44 . The plunging style constant velocity joints  44  are operatively connected to the front differential  18 . The plunging style constant velocity joints  44  are plug in style in this embodiment. However, any style of constant velocity joint half shaft assembly, may be used depending upon the application. In the embodiment illustrated, the stem portion of each joint  42  is splined such that each joint  42  interacts with a front wheel  46  of vehicle  10  and has a threaded portion which also connects the wheel  46  to half shaft assembly  34 ,  36 . As also shown in  FIG. 2 , constant velocity joint boots  48  are utilized to contain constant velocity joint lubricant, which generally is grease, within the constant velocity joint to keep the constant velocity joints lubricated for life.  
         [0024]     The power take off unit  20  may be mounted to the face of a transmission of vehicle  10  (not numbered) and receives torque from the front differential  18 . The transmission is operatively connected to an engine of the vehicle  10  (not numbered). In the embodiment illustrated, the front differential  18  has the same gear ratio as the rear differential  32  and drives the front prop shaft  24  through the high speed fixed joint  22  from the front differential axis.  
         [0025]     With reference to  FIGS. 3-5 , and as mentioned earlier, high speed fixed joint  22  is connected at one end of the front differential  18  and at the other end to a front prop shaft  24 . A VL type plunging constant velocity joint  26  is connected to the rear prop shaft  28  and to front prop shaft  24 . The high speed fixed joint  22  may have a revolution per minute (RPM) capacity of 6000 RPMs with the preferable range of three to five thousand RPMs, a torque capacity of five to fifteen hundred Newton meters, but the preferred capacity of six to seven hundred Newton meters, and an inner capacity of up to 15 degrees with a preferable capacity of three to six degrees. The drive system  12  may use other constant velocity joints and/or Cardan joints or universal joint technology although, a high speed fixed joint is preferred.  
         [0026]     The high speed fixed joint  22  includes a boot  50  which is utilized to enclose grease (not shown) required for lubrication of the high speed fixed joint  22 . The front prop shaft  24  in the present invention is manufactured from steel providing a very low run up and critical high speed capacity higher than the second engine order.  
         [0027]     Referring to  FIG. 6 , and as mentioned earlier, on the second end SE of the front propeller shaft  24  is a plunging VL constant velocity joint  26 . The plunging VL constant velocity joint  26  includes an outer race  54  with an inner race  56  arranged within the outer race  54 . The plunging constant velocity joint  26  also includes a cage  58  for supporting and locating a plurality of rolling elements  60  between an inner surface of the outer race  54  and an outer surface of the inner race  56 . The plunging constant velocity joint  26  has a stub shaft  62  rotatably fixed to an inner bore (not numbered) of the inner race  56 . The plunging VL constant velocity joint  26  mates with a rear flange  64  connected to one end of the front prop shaft  24  and to the outer race  54  of the VL plunging constant velocity joint  26  on an opposite end thereof. The rear flange  64  has a plurality of orifices  66  therein that will align with the plurality of orifices  68  through a surface of the outer race  54  of the VL plunging constant velocity joint  26  and allow for fasteners  70  to secure the VL plunging constant velocity joint  26  to the rear flange  64  and hence the front prop shaft  24  of the automotive vehicle. As best seen in  FIG. 4 , the rear flange  64  is coupled for rotation with the rear prop shaft assembly  28 .  
         [0028]     Referring to  FIG. 7 , the high speed fixed constant velocity joint  22  as described above is located on the front end FE of the propeller shaft  24 . The high speed fixed constant velocity joint  22  includes an outer race  72  with an inner race  74  arranged therein. A cage  76  and a plurality of rolling elements  78  are arranged between the inner race  74  and outer race  72  for transfer of constant velocity rotary motion through the high speed fixed joint  22 . The high speed fixed constant velocity joint  22  includes a front flange  52  that is connected to the front differential  18  on one end and to the outer race  72  of the high speed constant velocity joint  22  on the opposite end. The outer race  72  of the constant velocity joint  22  has a plurality of orifices  80  therethrough that mate with and align with a plurality of orifices through the front flange  52  of the high speed constant velocity joint  22 . The high speed fixed constant velocity joint  22  has a stub shaft  82  rotatably fixed to an inner bore (not numbered) of the inner race  74 . Fasteners  84  will connect the high speed constant velocity joint  22  to the front flange  52  during installation of the constant velocity joint.  
         [0029]     The high speed constant velocity joint  22  includes a grease cover  86  on one end thereof. The plunging VL constant velocity joint  26  also includes a grease cover  88  in contact with the outer race  54  and rear flange  64  of the VL constant velocity joint  26 . The grease covers  86 ,  88  will ensure the lubricant stays within the VL plunging constant velocity joint  26  and the high speed fixed joint  22  for proper lubrication of the joints.  
         [0030]     With brief reference to  FIG. 4 , the joint  22  and the front flange  52  collectively form a first connection apparatus  108 . Also, the joint  26  and the rear flange  64  collectively form a second connection apparatus  110 .  
         [0031]     With specific reference to  FIGS. 4 and 5 , the front propeller shaft assembly  24  includes the high speed fixed joint  22 , the constant velocity joint  26 , and an interconnecting member  120 . The interconnecting member  120  extends between the stub shaft  62  of the constant velocity joint  26  and the stub shaft  82  of the high speed constant velocity joint  22  (as also seen in  FIG. 7 ). The front flange  52  has a mounting surface  130  that mates with the outer race  72  of the high speed constant velocity joint  22  ( FIGS. 4 and 7 ), and a front flange contour surface  134 . The rear flange  64  has a mating surface  136  ( FIG. 6 ) that mates with the outer race  54  of the constant velocity joint  26 , and a rear flange contour surface  138 . The mounting surface  130  of front flange  52  is separated from the mounting surface  132  of rear flange  64  by a distance DF ( FIGS. 4 and 5 ).  
         [0032]     As best seen in  FIG. 4 , the first grease cover  86  has a first grease cover contour surface  140  that matingly contours the first flange contour surface  134 . As best seen in comparing  FIGS. 4 and 5 , the second grease cover  88  has a second grease cover mounting surface  142  and a second grease cover contour surface  144  that matingly contours the rear flange contour surface  138  to provide a visual notification of correct orientation of the propshaft portion within the propshaft system.  
         [0033]     As best seen in  FIG. 5 , when the propshaft  24  is incorrectly oriented in the propshaft system  12 , that is, when the fixed joint  22  is oriented farther from the front differential  18  than the plunging joint  26 , interference between the second grease cover  88  and the front flange  52  will provide a visual notification to a technician that the propshaft  24  is incorrectly oriented, and will prevent the propshaft  24  from being readily installed in an incorrect orientation. In the embodiment of  FIG. 5 , the interference is a contact between the second grease cover contour surface  144  and the front flange contour surface  134 . This interference prevents the front flange  52  mounting surface  130  from full contact with the second grease cover mounting surface  142 .  
         [0034]     According to an embodiment, the VL plunging constant velocity joint  26  has a lengthened grease cover  88 . In particular, as shown in  FIG. 6 , the grease cover or cap  88  will have a generally U-shaped cross section. The grease cover or cap  88  will also have a circumferential lip  90  generally having an L-shaped cross section at one end thereof. The grease cover  88  will have an extended or lengthened body  92  as shown. This extended or lengthened body  92  will have a predetermined depth GF2, which will penetrate into a bore  94  of the rear flange  64  of the VL plunging joint  26 . It should be noted that the improved grease cover  88  is currently made of a metal material, however any hard plastic, composite, ceramic or the like material may also be used.  
         [0035]     The bell portion or body  92  of the grease cover  88  will be lengthened a predetermined distance such that if the prop shaft  24  is mistakenly installed backwards (incorrect orientation) into the vehicle the lengthened grease cover  88  will prevent installation of the plunging constant velocity joint  26  into the high speed fixed joint front flange  52  via interference with a surface of the front flange  52  ( FIG. 5 ) and/or a mechanical stop as shown in  FIG. 9 . In an embodiment contemplated the incorrect installation of the prop shaft  24  will leave a minimum of a five millimeter gap  96  between the end of a fastener  70  of the plunging constant velocity joint  26  and a threaded orifice of the high speed fixed joint front flange  52 . This will ensure that the installer of the prop shaft  24  into the vehicle drive line of the automotive vehicle, cannot torque and secure the prop shaft  24  when orientated reversed, or backwards, within the drive system  12 .  
         [0036]     As shown in  FIG. 6  an embodiment may include a modified plunging VL rear flange  164  for use with the modified grease cover  188  for the plunging VL type joint  26 . The modified rear flange  164  includes an increased sized bore  94  that has been lengthened and widened to allow entry and mating with the lengthened grease cover  188  of the VL plunging joint  26 . As shown in  FIG. 6 , during proper installation of the prop shaft  24  the modified grease cover  188  will mate with an be allowed to be inserted within the expanded, in both a width and length direction, flange inner bore  94 . The modified grease cover  188 , after proper installation, will be in contact at the lip  90  with a surface of the VL plunging style rear flange  164  and the outer race  54  of the VL plunging style joint  26 . Therefore, with proper installation of the VL plunging joint  26  to the modified plunging rear flange  164  the fasteners  70  will be capable of being properly tightened while the fasteners  84  for the high speed fixed joint  22  (not shown) will be capable of being properly tightened and secured to the high speed fixed joint front flange  52  located at the front end FE of the front prop shaft  24 .  
         [0037]     It should be noted that the front flange  52  is preferably made of a steel material, however any other metal, hard plastic, composite, or the like may also be used depending on the design requirements of the drive line. It should be noted that it has been contemplated to leave a five millimeter gap  96  between the end of the fastener  70  and the threaded orifice of the high speed fixed joint front flange  52  however any other gap size may also be used depending on the design requirements and packaging requirements of the driveline. The modified grease cover  88  of the VL plunging constant velocity joint  26  will ensure that the fasteners are not tightened down and thus damage or crush the grease cover  88 , as happened sometimes with the prior art arrangement. The extended grease cover  88  for the VL plunging constant velocity joint  22 , expanded inner bore  94  for the VL rear flange  64  and front flange  52  together or in any combination provide a mechanical stop which will keep any installer from installing the prop shaft  24  backwards in the automotive vehicle driveline. Other contemplated embodiments are capable for the mechanical stop to create an in vehicle installation error proofing method for installation of a propeller shaft having common joint ends. It should be noted that the grease cover  88  in the embodiment shown has a length that ensures that if the prop shaft  24  is installed improperly into the high speed fixed joint front flange  52  it would create the five millimeter gap to ensure no tightening of the VL joint  26  with respect to the front flange  52 . Therefore, any size grease cover  88  and any size inner bore  94  for a rear flange  64  may be designed to create specific mechanical stop features for different prop shafts in vehicle drivelines.  
         [0038]     As shown in  FIG. 8 , the front flange  52  is illustrated in an alternative embodiment as a front flange  152 . Front flange  152  has an extension, or knob,  166  arranged at a center point or other portion of the high speed fixed constant velocity joint front flange  52 . It should be noted that the original high speed fixed joint front flange  52  may be designed such that installation of the modified VL plunging cover  88  is not even possible. However, it is contemplated to put an extension  166  into the inner bore of the high speed constant velocity joint front flange  152  to ensure a mechanical stop occurs thus ensuring the prop shaft  24  cannot be installed backwards within the motor vehicle drive system  12 . Therefore, further modification of the high speed fixed joint front flange  52  is also possible in an embodiment.  
         [0039]      FIG. 10  shows one methodology for insuring error proof installation of a prop shaft  24  in a motor vehicle driveline. In Step  200 , an operator will provide a propshaft having a first end and a second end. In Step  202 , one will determine a correct orientation for the propshaft within a propshaft system, typically with a plunging joint orientated nearest, the transmission and a fixed joint. In Step  204 , one will attach the first end of the propshaft directly to one of a first flange and a first constant velocity joint. In Step  206 , one will attach the second end of the propshaft directly to one of a second flange and a second constant velocity joint. In Step  208 , one will attach the first flange directly to the first constant velocity joint. In Step  210 , one will attach the second flange directly to the second constant velocity joint. Selective coupling of the first flange directly to the second grease cover will provide a visual notification of incorrect orientation of the propshaft within the propshaft system, as described herein.  
         [0040]     While the embodiments illustrated include modifications to a grease cover  88  to error proof an installation of a propshaft within a propshaft system, one may also modify the outer race  72  such that the grease cover  88  can not be attached thereto to prevent installation of the grease cover  88  on the joint  22 , to provide further error proof features.  
         [0041]     In the embodiment illustrated, the joints  22 ,  26  and front prop shaft  24  are interposed between front flange  52  and rear flange  64 , although in other embodiments the front prop shaft  24  may be affixed directly to front flange  52  and rear flange  64  with joint  22  interposed between the front flange  52  and front differential  18 , and the joint  26  interposed between the rear flange  64  and the rear prop shaft  28  to accomplish a similar error proof installation control feature.  
         [0042]     The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.