Patent Abstract:
A drive plate for a torque converter including first and second plates operatively arranged to be attached to a torque converter and a drive unit. In another embodiment, each of the first and second plates further includes at least one first opening and at least one second opening operatively arranged to receive a first and second fastener, respectively. In yet another embodiment, the drive plate includes a plurality of component plates operatively arranged to be attached to a torque converter and a drive unit.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/753,130, filed Dec. 22, 2005, which application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to torque converters, more particularly, to a torque converter drive plate, and, more specifically, to a multi-piece torque converter drive plate. 
     BACKGROUND 
     Hydraulic torque converters, devices used to change the ratio of torque to speed between the input and output shafts of the converter, revolutionized the automotive and marine propulsion industries by providing hydraulic means to transfer energy from an engine to a drive mechanism, e.g., drive shaft or automatic transmission, while smoothing out engine power pulses. A torque converter, arranged between the engine and the transmission, includes three primary components, an impeller, sometimes referred to as a pump, directly connected to the converter&#39;s cover and thereby the engine&#39;s crankshaft; a turbine, similar in structure to the impeller, however the turbine is connected to the input shaft of the transmission; and, a stator, located between the impeller and turbine, which redirects the flow of hydraulic fluid exiting from the turbine thereby providing additional rotational force to the pump. 
     Although coupling the impeller to the engine, at first glance, may appear trivial, the means by which the coupling is accomplished can radically effect the performance and efficiency of the engine and torque converter, e.g., resulting in varying horsepower at the wheels. The push for increased fuel economy/gas mileage and decreased manufacturing costs encouraged the development of torque converter drive plates having various configurations. For example, in one design, tabs or extensions are forged or welded on a torque converter cover, thereby providing an integral means of coupling a converter to an engine. Although this design may be quite simple, it does however introduce a significant amount of dense material to the torque converter assembly, and consequently introduces a significant mass to the assembly. 
     As the torque converter must rotate in order to transfer torque between the engine and the transmission, any added mass to the torque converter must also be rotated during this transfer process. Due to the principle of mass moment of inertia, i.e., a measure of a solid object&#39;s resistance to changes in rotational speed about its rotational axis, it can be shown mathematically that an object having a greater mass will have a greater mass moment of inertia. The mass moment of inertia I for a torque converter can be approximated by the following formula used for a thin disk having a radius r and a mass m: 
             I   =       m   ⁢           ⁢     r   2       2           
Thus it can be seen that I is directly proportional to m, and therefore as m increases, I also increases. In view of this relationship between resistance to rotation, i.e., the amount of power required by the engine to drive the torque converter, and the mass of the object rotating, the resistance to rotation may be decreased by removing mass from the torque converter.
 
     One design which reduces the mass of the torque converter assembly is shown in the embodiment depicted in  FIG. 1 , i.e., a single stamped drive plate. In this design, the large mass of the welded or forged tabs is replaced by the reduced mass of the stamped plate. A secondary benefit of the single piece drive plate is the reduced cost of stamping operations verses the higher cost of forging or welding operations. Thus, the single stamped plate of  FIG. 1  provides both a manufacturing cost savings as well as a mass reduction over the welded and/or forged tabs. However, the single plate design requires a significant amount of material for each stamping, i.e., a large amount of material for a drive plate and scrap material from the central region of the plate. Additionally, due to overall part size, a limited number of drive plates may be produced from a given length of sheet metal stock (see  FIG. 10 ). 
     As can be derived from the variety of devices and methods directed at providing means to couple a torque converter to an engine, many means have been contemplated to accomplish the desired end, i.e., strong, reliable coupling, without sacrificing mass moment of inertia, and thus resulting in higher fuel efficiency and performance. Heretofore, tradeoffs between strength and reliability of coupling means and material mass for such means were required. Thus, there has been a longfelt need for a torque converter drive plate having high strength and reliability, while introducing a minimal mass to the overall torque converter assembly. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention broadly includes a torque converter drive plate having a first and second plate. In one embodiment, the first and second drive plates are operatively arranged to be secured to a torque converter. In another embodiment, each of the first and second plates further includes at least one first opening arranged to receive a first fastener, and at least one second opening arranged to receive a second fastener. In various embodiments, the first fastener may include a rivet, a first bolt, a weld or other fastening means known in the art. In other embodiments, the second fastener may include a stud, a lug, a second bolt or other coupling means known in the art. 
     In yet another embodiment, the torque converter drive plate includes a plurality of component plates operatively arranged to be fixedly secured to a torque converter. In this embodiment, each plate in the plurality of component plates further includes at least one first opening and at least one second opening, wherein each first opening is operatively arranged to receive a first fastener and each second opening is operatively arranged to receive a second fastener. 
     A general object of the invention is to provide means to couple an engine and a torque converter. 
     Another object of the invention is to minimize the mass of a torque converter assembly. 
     Yet another object of the invention is to minimize material losses during manufacture of a torque converter drive plate. 
     These and other objects, features, and advantages of the present invention will become readily apparent to one having ordinary skill in the art upon reading the detailed description of the invention in view of the drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
         FIG. 1  is a perspective view of a torque converter cover including a prior art torque converter drive plate; 
         FIG. 2  is a front elevational view of the torque converter cover of  FIG. 1 ; 
         FIG. 3  is a cross sectional view of the torque converter cover of  FIG. 1  taken generally along line  3 - 3  in  FIG. 2 ; 
         FIG. 4  is a perspective view of a torque converter cover including an embodiment of a torque converter drive plate of the present invention; 
         FIG. 5  is a front elevational view of the torque converter of  FIG. 4 ; 
         FIG. 6  is a cross sectional view of the torque converter cover of  FIG. 4  taken generally along line  6 - 6  in  FIG. 5 ; 
         FIG. 7  is a perspective view of the torque converter drive plate of  FIG. 4  shown without the torque converter; 
         FIG. 8  is a perspective view of a torque converter cover including a second embodiment of a torque converter drive plate of the present invention; 
         FIG. 9  a front elevational view of the torque converter cover of  FIG. 8 ; 
         FIG. 10  is a cross sectional view of the torque converter cover of  FIG. 8  taken generally along line  10 - 10  in  FIG. 9 ; 
         FIG. 11  is a perspective view of the torque converter drive plate of  FIG. 8  shown without the torque converter; 
         FIG. 12  is a top plan view of a length of metal sheet stock showing a stamping pattern for the torque converter drive plate of  FIG. 1 ; 
         FIG. 13  is a top plan view of a length of metal sheet stock showing a stamping pattern for the torque converter drive plate of  FIG. 4 ; and, 
         FIG. 14  is a front elevational view of a torque converter cover including yet another embodiment of a torque converter drive plate of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention as claimed is not limited to the preferred embodiment. 
     Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described. 
     Adverting now to the figures,  FIGS. 1 through 3  show torque converter cover  10  including prior art torque converter drive plate  12  wherein  FIG. 1  shows a perspective view of torque converter cover  10 ,  FIG. 2  is a front elevational view of torque converter cover  10 , and  FIG. 3  is a cross sectional view of torque converter cover  10  taken generally along line  3 - 3  in  FIG. 2 . Torque converter cover  10  is enclosed by cover  13  and provides a surface to which drive plate  12  is attached. Drive plate  12  includes holes  14  wherein rivets  16  are disposed, thereby fixedly securing drive plate  12  to torque converter cover  10 . Drive plate  12  further incorporates studs  18  disposed about a bolt circle complimentary to a bolt circle disposed about the engine flex plate (not shown). As described infra, drive plate  12  requires a significant amount of sheet metal stock to produce, and the circular region at the center of drive plate  12  is also lost as scrap. 
     As shown in  FIG. 3 , studs  18  are disposed at radius  19 , wherein radius  19  is the distance between center of rotation  20  of torque converter cover  10  and the center of studs  18 . Radius  19  is derived from the radius of torque converter cover  10  and the radius of the engine fly wheel (not shown). Various requirements, e.g., torque and size, determine the radius of torque converter cover  10 , while the engine flex plate radius is likely determined by another design group. Thus, for each set of vehicle requirements, a unique radius  19  may be required, and therefore a unique drive plate  12 . 
       FIGS. 4 through 7  show torque converter cover  22  including an embodiment of the instant invention, i.e., torque converter drive plates  24 , wherein  FIG. 4  is a perspective view of torque converter cover  22 ,  FIG. 5  shows a front elevational view of torque converter  22  of  FIG. 4 , while  FIG. 6  shows a cross sectional view of torque converter cover  22  taken generally along line  6 - 6  in  FIG. 5 , and lastly  FIG. 7  shows a perspective view of torque converter drive plates  24 . In the embodiments shown in these figures, torque converter drive plates  24  include holes  26  wherein rivets  28  are disposed, thereby fixedly securing drive plates  24  to cover  30  of torque converter  22 . 
     As shown in  FIG. 4 , drive plates  24  may be fixedly secured to cover  30  with a plurality of rivets  28 , however, as one of ordinary skill in the art would appreciate, other methods of fixedly securing drive plates  24  to cover  30  are also possible, e.g., bolts or welds, and such methods are within the spirit and scope of the invention as claimed. Drive plates  24  further include studs  32  disposed within raised portions  34  of drive plates  24 . When torque converter cover  22  is installed in a vehicle (not shown), the distance between torque converter cover  22  and the engine flex plate (not shown) may vary. Thus, providing a means to easily modify the clearances becomes particularly important. As such, drive plates  24  are provided with raised portions  34 , i.e., the distance between locating surface  36  and coupling surface  38 , which portions may be varied dependant upon the specific requirements of the assembly, including having no raised portions  34 . Additionally, this affords a torque converter developer the opportunity to design the converter based on the requirements of fluid dynamics, while still maintaining a simple means to couple the converter between the engine flex plate and the transmission. 
       FIG. 6  depicts studs, or bolts,  32  disposed in respective openings  33  at radius  39 , wherein radius  39  is the distance between center of rotation  40  of torque converter  22  and the center of studs  32 . Also shown in  FIG. 6  are turbine  100  and pump  102 . As described supra, radius  39  is derived from the radius of torque converter cover  22  and the radius of the engine fly wheel (not shown). Various requirements, e.g., torque and size, determine the radius of torque converter cover  22 , while the engine flex plate radius is likely determined by another design group. Thus, for each set of vehicle requirements, a unique radius  39  may be required and therefore unique drive plates  24 . Also shown in  FIG. 6  is height  41 , wherein height  41  is the distance between locating and coupling surfaces  36  and  38 , respectively, of drive plates  24 . Similar to the requirements of radius  39 , height  41  is the result of the combination of design specifications, e.g., torque converter power or size, and flex plate dimensions, and therefore height  41  may vary with different configurations. In  FIG. 6 , flex plate  35  is shown. In one embodiment, studs  32  can be inserted through openings  37  in the flex plate to connect drive plates  24  to the flex plate. In one embodiment, rivets  28  are extruded from cover  30  as shown in  FIG. 6 . 
       FIGS. 8 through 11  show torque converter drive plates  42 , wherein  FIG. 8  is a perspective view of torque converter cover  44  including another embodiment of the instant invention, i.e., torque converter drive plates  42 ,  FIG. 9  shows a front elevational view of torque converter cover  44  of  FIG. 8 , while  FIG. 10  shows a cross sectional view of torque converter  44  taken generally along line  10 - 10  in  FIG. 9 , and lastly  FIG. 11  shows a perspective view of torque converter drive plates  42 . In the embodiments shown in these figures, torque converter drive plates  42  include holes  46  wherein rivets  48  are disposed, thereby fixedly securing drive plates  42  to cover  50  of torque converter cover  44 . 
     Similar to the embodiment shown in  FIGS. 4 through 7 , drive plates  42  may be fixedly secured to cover  50  with a plurality of rivets  48 , and as one of ordinary skill in the art would appreciate, other methods of fixedly securing drive plates  42  to cover  50  are also possible, e.g., bolts or welds, and such methods are within the spirit and scope of the invention as claimed. In like fashion, drive plates  42  further include studs  52  disposed within raised portions  54  of drive plates  42 . When torque converter cover  44  is installed in various vehicles (not shown), the assembly likely has varying distance requirements between torque converter cover  44  and the engine flex plate (not shown), and hence, providing a means to easily modify the clearances becomes particularly important. As such, drive plates  42  are provided with raised portions  54 , i.e., the distance between locating surface  56  and coupling surface  58 , which portions may be varied dependant upon the specific requirements of the assembly, including having no raised portions  54 . As described supra, this affords a torque converter developer the opportunity to design the converter based on the requirements of fluid dynamics, while still maintaining a simple means to couple the converter between the engine flex plate and the transmission. 
     A plurality of locations wherein studs  52  may be disposed within drive plates  42  are also shown in these figures. In this embodiment, studs  52  are disposed in first position  60 , although studs  52  may similarly be disposed in second and third locations  62  and  64 , respectively, dependant on design specifications. This affords a manufacturer of torque converter drive plates the opportunity to merely stamp a single configuration of a drive plate, for example drive plates  42 , and provide those drive plates to customers having various stud location requirements. 
       FIG. 10  depicts studs  52  disposed at first radius  66 , wherein first radius  66  is the distance between center of rotation  68  of torque converter  44  and the center of studs  52 . Again, as described supra, first radius  66  is derived from the radius of torque converter  44  and the radius of the engine fly wheel (not shown). As each set of vehicle requirements may set forth a unique stud radius, and therefore unique stud locations within drive plates  42 , various radii, e.g., first, second and third radii  66 ,  70  and  72 , respectively, are offered in this single embodiment of the instant invention. Similar to other embodiments, height  74  is the distance between locating and coupling surfaces  56  and  58 , respectively, of drive plates  42 , and as height  74  is the result of the combination of design specifications, e.g., torque converter power or size, and flex plate dimensions, height  74  may vary. 
       FIG. 12  shows a top plan view of a length of metal sheet stock  76 , depicting stamping pattern  78  for the prior art torque converter drive plate  12  shown in  FIGS. 1 through 3 , while  FIG. 13  shows a top plan view of a length of metal sheet stock  80 , depicting stamping pattern  82  for an embodiment of the instant invention, i.e., torque converter drive plate  24  shown in  FIGS. 4 through 7 . As shown in  FIGS. 11  and  12 , for a given length of metal sheet stock  76  and  80 , respectively, a greater number of torque converter drive plates  24  may be produced than torque converter drive plates  12 . Thus, consumed material  84 , i.e., the material required to produce a single drive plate  12 , is far greater than consumed material  86 , i.e., the material required to produce a single drive plate  24 . Although two drive plates  24  are required to replace a single drive plate  12 , the combination of two consumed materials  86  remains less than a single consumed material  84 . Hence, the material required to produce two drive plates  24  is less than the material required to produce one drive plate  12 , even when material not used in either plate is included, i.e., scrap material from the stamping process. 
       FIG. 14  shows a front elevational view of torque converter cover  88  including yet another embodiment of the instant invention, torque converter drive plates  90 . In this embodiment, four drive plates  90  are fixedly secured to cover  92 . Thus, each individual drive plate  90  provides a single coupling means, i.e., stud, or bolt,  94 , whereby torque converter cover  88  may be fixedly secured to the engine flex plate (not shown). Stud or bolt  94  is inserted Through opening  93 . Similar to other embodiments, drive plates  90  also include rivets  96  disposed within holes  98 , thereby fixedly securing drive plates  90  to cover  92 . Although four drive plates  90  are shown in  FIG. 14 , one of ordinary skill in the art would appreciate that other numbers of drive plates are also possible, e.g., three or five, and such configurations are within the spirit and scope of the invention as claimed. 
     Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, which modifications are intended to be within the spirit and scope of the invention as claimed. It also is understood that the foregoing description is illustrative of the present invention and should not be considered as limiting. Therefore, other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.

Technology Classification (CPC): 5