Abstract:
A driveline system for an automotive driveline system includes a transmission device, a differential device, and a universal joint having a drive shaft presenting terminal ends and interconnecting the transmission and differential devices. A yoke is connected to each of the terminal ends of the drive shaft and presents an internal surface and an external surface having generally equal thickness defined therebetween to form a dish of the yoke having a tubular monolithic structure. The yoke portion includes a bottom and a pair of spaced lugs each presenting sloping side walls for reinforcing the lugs as said yoke is rotated around a longitudinal axis.

Description:
RELATED APPLICATIONS  
       [0001]     This is a non-provisional patent application that claims the benefit of the provisional patent application Ser. No. 60/623,674 for a VEHICLE HAVING A UNIVERSAL JOINT DEVICE AND A PROCESS OF MAKING THE SAME, filed on Oct. 29, 2004 and 60/636,190 for a UNIVERSAL JOINT ASSEMBLY FOR AN AUTOMOTIVE DRIVELINE SYSTEM, filed on Dec. 15, 2004, which are hereby incorporated by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The subject invention relates generally to a driveline system for a vehicle transmission. More particularly, the present invention relates to a universal joint component of the driveline system and a method of forming the same.  
         [0004]     2. Description of the Prior Art  
         [0005]     A drive axle assembly of an automotive vehicle transmits torque from an engine and a transmission to drive vehicle wheels. The drive axle assembly changes the direction of the power flow, multiplies torque, and allows different speeds between the two of the drive wheels. The drive axle assembly includes a plurality of components engaged in operative communication one with the other. One of these components is a universal joint. Typically, the universal joint includes a pair of bifurcated yokes or yoke portions, which are secured to drive shafts and which are interconnected by a cruciform for rotation about independent axes. The cruciform includes four orthogonal trunnions with each opposing pair of axially aligned trunnions mounted in a pair of aligned bores formed in the bifurcated yokes.  
         [0006]     Typically, a bearing cup is secured in each bore and a bearing assembly is retained in the bearing cup such that each yoke is supported for pivotal movement relative to a pair of the trunnions. Various conventional universal joints having yoke portions are known to those skilled in the vehicle driveline art and are widely used in the automotive industry today. These universal joints are disclosed in U.S. Pat. No. 4,307,833 to Barnard; U.S. Pat. No. 5,601,377 to Ohya; U.S. Pat. No. 5,622,085 to Kostrzewa; U.S. Pat. No. 5,845,394 to Abe et al.; U.S. Pat. No. 6,162,126 to Barrett et al.; U.S. Pat. No. 6,280,335 to Wehner et al.; U.S. Pat. No. 6,336,868 to Kurecka et al.; U.S. Pat. No. 6,408,708 to Sahr; U.S. Pat. No. 6,591,706 to Harer et al.; and U.S. Pat. No. 6,736,021 to Adams et al.  
         [0007]     The U.S. Pat. No. 5,601,377 to Ohya, for example, teaches an automobile steering column that transmits the rotation of the steering wheel to the steering gearbox. For increasing the degree of freedom of geometric arrangement of the steering system, the steering column has a plurality of steering shafts which are connected with each other by universal joints. The universal joint, taught by the U.S. Pat. No. 5,601,377 to Ohya, has a pair of conventional yokes and a cross member. Each yoke has a base portion and a pair of arm portions or lugs opposed to each other in a diametral direction of the yoke and extend in an axial direction of the yoke. Each arm portion has a circular opening and sides extending in a parallel relationship with the axial direction of the yoke. The yoke of the U.S. Pat. No. 5,601,377 to Ohya is taught to be connected to a steering shaft and is not subjected to numerous rotational movements as, for example, a yoke portion connected to a universal joint of a driveline and is, therefore, not considered as being feasible for use on the driveline. In addition, the yoke does not include reinforcing features of any kind to prevent bending of the arm portions during rotation of the yoke.  
         [0008]     The U.S. Pat. No. 5,845,394 to Abe et al., for example, teaches a method of manufacturing a yoke portion having two spaced lugs for a universal joint from a blank of a sheet metal to receive the yoke portion of a uniform thickness. Similar to the yoke taught by the aforementioned U.S. Pat. No. 5,601,377 to Ohya, the spaced lugs are not reinforced to provide structural integrity of the yoke portion. Again, the yoke portion is taught to be connected to a steering shaft and is not subjected to numerous rotational movements as, for example, a yoke portion connected to a universal joint of a driveline and is, therefore, not considered as being feasible for use on the driveline.  
         [0009]     To reduce the effect of vibration and the resulting noises, manufacturers have used various methods to construct drive shafts and universal joints connected thereto. Typical prior art yoke portions are iron cast to provide durability but are difficult to balance.  
         [0010]     The opportunity exists for an improved universal joint and method of manufacturing the same that will reduce the mass of the yoke portion thereby reducing the effect of vibrations and the resulting noises, add structural integrity to the universal joint, make it easier to balance, and increase performance of drive line applications at a low cost and a high volume.  
       BRIEF SUMMARY OF INVENTION  
       [0011]     A differential assembly for an automotive driveline system includes a transmission device, a differential device, and at least one drive shaft that extends between the transmission and differential devices. The drive shaft presents an operative communication with the transmission device and the differential device. A universal joint device rotates around a longitudinal axis and presents operative communication with the transmission device and the differential device. The universal joint device includes at least one yoke portion having a dish defining an internal surface and an external surface. A generally equal thickness is defined between the internal surface and the external surface of the dish to form a generally monolithic and tubular construction of the yoke portion. The dish is defined by a bottom and an annular wall integral with the bottom. The annular wall extends to a pair of spaced lugs diametrically disposed with respect to one another. Each lug extends outwardly to a head. Each lug presents a neck being wider in width than the head and sloping side walls interconnecting the head with the neck for reinforcing the yoke portion as the yoke portion rotates around the longitudinal axis. Each lug is reinforced by at least one indentation or dimple press formed in the lug in a shape of a gusset or a rib.  
         [0012]     A connector extends between the yoke portion to mechanically engage at least one of the transmission devices and the differential device to yoke portion thereby defining the aforementioned operative communication. The inventive yoke portion reduces vibration of the universal joint connected to the yoke portion of the generally equal thickness as the universal joint rotates about the longitudinal axis.  
         [0013]     An advantage of the present invention is to provide an improved yoke portion for a universal join that is stamped from a sheet metal presenting a light weight alternative to an iron cast yoke portion known in the prior art, which reduces the effect of vibrations and the resulting noises.  
         [0014]     Another advantage of the present invention is to provide an improved yoke portion that reduces the mass of the improved yoke portion thereby making it easier to balance and increase performance of the driveline applications at a low cost and a high volume.  
         [0015]     Still another advantage of the present invention is to provide an improved yoke portion having a pair of spaced lugs and at least one gusset defined in each of the spaced lugs to provide structural integrity to the yoke portion that reduces the effect of vibrations and the resulting noises and increases performance of the driveline system at a low mass.  
         [0016]     Still another advantage of the present invention is to provide an improved yoke portion wherein each spaced lug presents a central axis and sloping side walls inclined from the head to the neck thereby reducing stress applied to the yoke portion and preventing the spaced lugs from bending as the yoke portion rotates around the longitudinal axis. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     Other 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 wherein:  
         [0018]      FIG. 1  shows an elevational view of a vehicle frame having a driveline system;  
         [0019]      FIG. 2  is an exploded view of a universal joint assembly;  
         [0020]      FIG. 3  is a perspective view of a yoke portion of the universal joint assembly;  
         [0021]      FIG. 4  is a cross sectional view of the yoke portion shown in  FIG. 3 ;  
         [0022]      FIG. 5  is an elevational view of the yoke portion shown in  FIG. 3 ;  
         [0023]      FIG. 6  is a side and partially cross sectional view of the yoke portion shown in  FIG. 3  connected laser or spin welding to a drive shaft of various diameters;  
         [0024]      FIG. 7  an end view of the yoke portion shown in  FIG. 6 ;  
         [0025]      FIG. 8  is a perspective view of an alternative embodiment of the yoke portion of the universal joint assembly;  
         [0026]      FIG. 9  is a cross sectional view of the yoke portion shown in  FIG. 8 ;  
         [0027]      FIG. 10  is an end view of the yoke portion shown in  FIG. 8 ; and  
         [0028]      FIG. 11  is a side and partially cross sectional view of the yoke portion shown in  FIG. 8  mechanically connected to the drive shaft;  
         [0029]      FIG. 12  is a top view of the progressive stamping stages of forming the yoke portion;  
         [0030]      FIG. 13  is a cross sectional view of the yoke portion having an annular sleeve circumscribing an opening defined in spaced lugs of the yoke portion formed by a stamping process;  
         [0031]      FIG. 14  is a fragmental perspective view of the yoke portion having the annular sleeve taken from the inner side of the yoke portion; and  
         [0032]      FIG. 15 a  cross sectional view of an alternative embodiment of the yoke portion having the spaced lugs of increased thickness formed by a stamping process. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]     Referring to  FIG. 1 , a chassis of an automotive vehicle, generally shown at  10 , includes a frame  12  and a driveline mechanism. The driveline mechanism includes a transmission assembly  14 , a differential assembly  16 , and two universal joints, generally indicated at  18 , extending between the transmission assembly  14  and the differential assembly  16  presenting an operative communication therebetween. The universal joint  18  rotates around a longitudinal axis A during its operational mode. The universal joint  18 , as better illustrated in  FIG. 2 , includes a first drive shaft  19  and a second drive shaft  20  with a pair of yokes, such as, for example a first yoke  24  and a second yoke  26 . The first yoke  24  is attached to the first drive shaft  19  and the second yoke or yoke portion  26  is attached to the second drive shaft  20 .  
         [0034]     A connector or cruciform assembly, generally shown at  28 , interconnects the first yoke  24  and the second yoke  26 . The cruciform assembly  28  includes a cross member, generally indicated at  30 , has a central hub  32  and a pair of first trunnions  34  and  36  and a pair of second trunnions  38  and  40 . The first trunnions  34  and  36  are orthogonal with respect to the second trunnions  38  and  40 , with all of the trunnions  34 ,  36 ,  38 , and  40  aligned within a common plane. The first trunnions  34  and  36  are cylindrical and are adapted for insertion into the first yoke  24 . Similarly, the second trunnions  38  and  40  are cylindrical and are adapted to be inserted into the second yoke  26 . The cruciform assembly  28  and the first yoke  24  are known to those skilled in a differential art and are not described and/or illustrated in great details.  
         [0035]     Referring to  FIGS. 3 through 7  the second yoke  26  is illustrated in great details showing a preferred embodiment of the present invention. The second yoke  26  is connected to each of the terminal ends of the second drive shaft  20  and presents an internal surface, generally indicated at  42 , and an external surface, generally indicated at  44 . The second yoke  26  presents a generally equal thickness defined between the internal surface  42  and the external surface  44 . A cup portion or a dish  46  of the second yoke  26  includes a frustoconical configuration. The cup portion  46  has a bottom or base  50  defined by an upper annular wall  52 .  
         [0036]     A pair of spaced lugs  58  and  60  extend outwardly to a head  62 ,  64 , respectively, from the annular wall  52 . Sloping side walls  66  and  68  interconnect each of the heads  62  and  64  with the annular wall  52  to define a neck, generally indicated at  70 , of each of the spaced lug  58  and  60 . Each sloping side wall  66  and  68  presents an acute angle defined between the axis A and each sloping side wall  66  and  68 . Each of the spaced lugs  58  and  60  includes an opening  72 . Preferably, the diameter of the opening  72  equals the distance defined between the opening  72  and the bottom or base  50  the cup portion  46 . The spaced lugs  58  and  60  are oriented diametrically with respect to one and the other. Each of the spaced lugs  58  and  60  includes an annular sleeve  74  integral with and circumscribing the opening  72 . The annular sleeve  74  extends outwardly from the internal surface  42  of the second yoke  26 . The annular sleeve  74  presents a mechanical engagement with a pair of the first  34 ,  36  or second  38 ,  40  trunnions of the cruciform assembly  28  in a manner known to those skilled in the differential art. In addition, the annular sleeve  74  provides additional structural reinforcement for locking the pair of the first  34 ,  36  or second  38 ,  40  trunnions of the cruciform assembly  28  within and between the spaced lugs  58  and  60 .  
         [0037]     A plurality of notches  78  and  80  are defined in the annular wall  52 . A pair of oppositely spaced tabs  82  and  84  is defined between each of the notches  78  and  80 . Each of the spaced tabs  82  and  84  terminates in a folded lip portion  86  to strengthen the second yoke  26  in this area of cut off. A pair of dimples  90  and  92  are formed in each of the spaced lugs  58  and  60 . Each dimple  90  and  92  is concavely curved to define a cavity as viewed from the external surface  44  of the yoke portion and a beveled configuration as viewed from the internal surface  42 . Each dimple  90  and  92  extends from each spaced lug  58  or  60  to the bottom or base  50  the cup portion  46  with each of said dimples  90  and  92  formed below the annular sleeve  74 . The dimples  90  and  92  are designed to strengthen the spaced lugs  58  and  60 .  
         [0038]     Referring to  FIG. 6 , the yoke portion  26  is connected to the first drive shaft  19  or the second drive shaft  20  of various diameters, which may vary from 3″ to 3.5″, respectively, by welding. Preferably, laser welding is used to connect. Laser welding uses amplified light as the source to produce the weld, i.e. specific wave length of light to accomplish the welding process. As a high production welding process, laser welding produces deep penetration welds with minimum heat effective zones and has the advantage of welding dissimilar metals while producing very low heat. Laser welding is faster, cleaner, and more cost effective for manufacturing the inventive concept.  
         [0039]     Alternatively, the yoke portion  26  and the drive shaft  19  or  20  may be connected by spin or friction welding. Spin or friction welding uses heat generated by rotational friction at the joint line defined between the yoke portion  26  the drive shaft  19  or  20  to weld them together. A machine (not shown) applies pressure axially while rotating one of the part, such as, for example, the yoke portion  26  against its stationary positioned mate, such as, for example, the drive shaft  19  or  20 , and the resulting friction generates heat that melts the parts together. Advantages of the spin welding process, used in the present invention, include high quality permanent joints, hermetic seals, lower equipment costs, ease of assembly, energy efficient operation, no ventilation required, immediate handling, entrapment of other parts, far-field welding capability and no additional material requirements.  
         [0040]     The second yoke  26  includes an alternative embodiment, generally shown at  100  in  FIGS. 8 through 11 . The second yoke  100  presents a generally equal thickness defined between the internal surface, generally indicated at  102 , and the external surface, generally indicated at  104 . A cup portion or dish  106  of the second yoke  100  includes a frustoconical configuration. The cup portion  106  has a bottom or base defined by an annular wall  110  and forming the cup portion  106 . A neck  112  extends outwardly from the annular wall  110 . The neck  112  has a diameter sized to receive the drive shaft  20 .  
         [0041]     As best shown in  FIGS. 10 and 11 , a plurality of circumferentially spaced female connectors  116  are defined in the neck  112  to mechanically engage the second drive shaft  20 . A plurality of male connectors or protuberances  118  are defined in the internal surface of the drive shaft  20 . The male connectors  118  of the drive shaft  20  mechanically engage the female connectors  116  of the second yoke  100 , thereby preventing longitudinal and lateral movement of the second yoke  100  during rotation of the universal joint  18  about the longitudinal axis A, which reduces vibration of the universal joint  18  connected to the second yoke  100 .  
         [0042]     A pair of spaced lugs  120  and  122  extends outwardly from the cup portion  106 . Each of the spaced lugs  120  and  122  presents an opening  124 . The spaced lugs  120  and  122  are oriented diametrically with respect to one and the other. Each of the spaced lugs  120  and  122  includes an annular sleeve  126  integral with and circumscribing the opening  124 . Each of the spaced lugs  120  and  122  includes side walls  128  and  130  sloping relative the longitudinal axis A. The dish  106  and each of the sloping side walls  128  and  130  are interconnected by scalloped corners, as shown in  FIGS. 8 and 10 . Alternatively, the dish  106  and each of the sloping side walls  128  and  130  are interconnected by non-scalloped corners, not illustrated in the present invention. The annular sleeve  126  extends outwardly from the internal surface  102  of the second yoke  100 . The annular sleeve  126  presents a mechanical engagement with a pair of the first  34 ,  36  or second  38 ,  40  trunnions of the cruciform assembly  28  in a manner known to those skilled in the differential art. In addition, the annular sleeve  126  provides additional structural reinforcement for locking the pair of the first  34 ,  36  or second  38 ,  40  trunnions of the cruciform assembly  28  within and between the spaced lugs  120  and  122 . A plurality of notches  132  and  134  are defined in the cup portion  104 .  
         [0043]     A pair of oppositely spaced tabs  136  and  138  is defined between each with each notch  132  and  134 . Each of the spaced tabs  136  and  138  terminates in a folded lip portion  140  to strengthen the second yoke  100  in this area of cut off. An indentation or muscle, generally indicated at  142 , is deformed in each of the spaced lugs  120  and  122  for strengthening the spaced lugs  120  and  122 . The muscle  142  is formed by stamping the external surface  104  of the second yoke  100  to form a concavely curved cavity, which extends to a convexly curved portion of the gusset  142  as viewed from the internal surface  102 . Preferably, the gusset  142  presents a triangular configuration as viewed from the external surface  104  of the second yoke  100  and a beveled triangular configuration as viewed from the internal surface  102 .  
         [0044]     The yoke portions  26  and  100  are formed by a progressive stamping, generally shown at  150  in  FIG. 12 , which is distinguished from machining, the shaping of metal by removing material (drilling, sawing, milling, turning, grinding, etc.) and from casting, wherein metal in its molten state is poured into a mold, whose form it retains on solidifying. The progressive stamping  150  is a metalworking process that can encompass punching, coining, bending and several other ways of modifying metal raw material, a strip of metal, generally indicated at  152 , as it unrolls from a coil (not shown), supplied by an automatic feeding system (not shown). The automatic feeding system pushes the strip of metal  152  in a progressive direction  154  through all of the stations or stages of the progressive stamping  150 , as discussed further below. Each station performs one or more operations until a finished part, such as the yoke portion  26  or  100  is formed. These operations are perforemed by a progressive stamping die (not shown). The progressive stamping die is placed into a reciprocating stamping press (not shown). As the reciprocating stamping press moves up, the progressive stamping die opens. When the progressive stamping press moves down, the progressive stamping die closes.  
         [0045]     When the stamping press opens, the strip of metal  152  is feed therein by the automatic feeding system pushes the strip of metal  152  in the progressive direction  154 , as best illustrated in  FIG. 12 . As the stamping press closes, the progressive stamping die performs work on the raw material.progressive stamping die, such as punching a contour  156  of the yoke portion, which includes the aforementioned spaced luggs and a bottom of the yoke portion. As the progressive stamping  150  proceeds, the openings  72 ,  124  are punched out in each of the spaced lugs and the bottom of the yoke portion is stamped or deformed into the aforementioned dish. As the automatic feeding system pushes the strip of metal  152  in the progressive direction  154 , the spaced lugs are bent to extend substantially perpendiculat to the bottom of the yoke portion. As the the strip of metal  152  is feed along the progressive direction  154  a button member  160  is inserted between the spaced lugs to provide a support for the spaced lugs as a pair of opposite die members  162  and  164  are oriented to form the annular sleeves  74  or  126 . The mechanical aspects of the opposite die members  162  and  164  are known to those skilled in the stamping art. A pair of sliding mechanisms  166  and  168  of the respective opposite die members  162  and  164  terminated into a press die  170  and  172 . The diameter of each press die  170  and  172  is larger than the diameter of the openings  72 ,  124  to facilitate stamping of the annular sleeves  74 ,  126  as the sliding mechanisms  166  and  168  are moved towards one and the other in the respective punching directions  172  and  174  as the press dies  170  and  172  force the metal around the openings  72 ,  124  into the annular sleeve  74  and  126 . The final stage of the the progressive stamping  150  separates the finished part, i.e. the yoke portion  26  and  100  from a carrying web or link  178 . The carrying web or link  178 , along with metal that is punched away in the previous operations, is treated as scrap metal.  
         [0046]     The yoke portion  26  and/or  100  are manufactured from a high strength low allow steel manufactured by Worthington Steel Company. Preferably, a cold bending process is used to manufacture the yoke portion  26 . As compared to prior art heat treated of steel processes that leave carbon content on the part, which prevents two part from being properly fused in laser welding process, the cold bending is the most practical, accepted, and economical way to make large-radii bends and preserving structural integrity of the part, such as, for example, the yoke portion  26 .  
         [0047]     While the invention has been described with reference to an exemplary embodiment, 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 thereof. 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 appended claims.