Abstract:
A torque converter including a cover with at least one slot located about a periphery and a pump with at least one protrusion located about a periphery of the pump. The protrusion extends axially through the slot and is bent radially about the slot to join the cover and the pump. In some aspects, the converter includes a sealing element disposed between the cover and the pump and the sealing element is selected from the group consisting of an o-ring and a gasket. A method of transferring torque including: inserting at least one peripherally disposed protrusion for one of a pump and cover of a torque converter through at least one peripherally disposed opening in the other of the pump and cover, radially bending the protrusion to clamp the cover and pump, and transmitting torque from the cover to the pump through the protrusion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/842,183 filed Sep. 1, 2006. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to improvements in apparatus for transmitting force between a rotary driving unit (such as the engine of a motor vehicle) and a rotary driven unit (such as a variable-speed transmission in the motor vehicle). In particular, the present invention relates to a torque converter with a cover and pump shell joined by slots and tabs. 
     BACKGROUND OF THE INVENTION 
       FIG. 1  illustrates a general block diagram showing the relationship of the engine  7 , torque converter  10 , transmission  8 , and differential/axle assembly  9  in a typical vehicle. It is well known that a torque converter is used to transmit torque from an engine to a transmission of a motor vehicle. 
     The three main components of the torque converter are the pump  37 , turbine  38 , and stator  39 . The torque converter becomes a sealed chamber when the pump is welded to cover  11 . The cover is connected to flexplate  41  which is, in turn, bolted to crankshaft  42  of engine  7 . The cover can be connected to the flexplate using lugs or studs welded to the cover. The welded connection between the pump and cover transmits engine torque to the pump. Therefore, the pump always rotates at engine speed. The function of the pump is to use this rotational motion to propel the fluid radially outward and axially towards the turbine. Therefore, the pump is a centrifugal pump propelling fluid from a small radial inlet to a large radial outlet, increasing the energy in the fluid. Pressure to engage transmission clutches and the torque converter clutch is supplied by an additional pump in the transmission that is driven by the pump hub. 
     In torque converter  10  a fluid circuit is created by the pump (sometimes called an impeller), the turbine, and the stator (sometimes called a reactor). The fluid circuit allows the engine to continue rotating when the vehicle is stopped, and accelerate the vehicle when desired by a driver. The torque converter supplements engine torque through torque ratio, similar to a gear reduction. Torque ratio is the ratio of output torque to input torque. Torque ratio is highest at low or no turbine rotational speed (also called stall). Stall torque ratios are typically within a range of 1.8-2.2. This means that the output torque of the torque converter is 1.8-2.2 times greater than the input torque. Output speed, however, is much lower than input speed, because the turbine is connected to the output and it is not rotating, but the input is rotating at engine speed. 
     Turbine  38  uses the fluid energy it receives from pump  37  to propel the vehicle. Turbine shell  22  is connected to turbine hub  19 . Turbine hub  19  uses a spline connection to transmit turbine torque to transmission input shaft  43 . The input shaft is connected to the wheels of the vehicle through gears and shafts in transmission  8  and axle differential  9 . The force of the fluid impacting the turbine blades is output from the turbine as torque. Axial thrust bearings  31  support the components from axial forces imparted by the fluid. When output torque is sufficient to overcome the inertia of the vehicle at rest, the vehicle begins to move. 
     After the fluid energy is converted to torque by the turbine, there is still some energy left in the fluid. The fluid exiting from small radial outlet  44  would ordinarily enter the pump in such a manner as to oppose the rotation of the pump. Stator  39  is used to redirect the fluid to help accelerate the pump, thereby increasing torque ratio. Stator  39  is connected to stator shaft  45  through one-way clutch  46 . The stator shaft is connected to transmission housing  47  and does not rotate. One-way clutch  46  prevents stator  39  from rotating at low speed ratios (where the pump is spinning faster than the turbine). Fluid entering stator  39  from turbine outlet  44  is turned by stator blades  48  to enter pump  37  in the direction of rotation. Elements  21  are rivets; elements  23  are turbine blades; elements  24  and  32  are torus rings; element  25  is a stator; element  26  is race; elements  27  are bearings; element  28  is a race; element  29  is an end plate; elements  33  are pump blades; element  34  is a pump shell; element  35  is a hub; and element  36  is a bushing. 
     The blade inlet and exit angles, the pump and turbine shell shapes, and the overall diameter of the torque converter influence its performance. Design parameters include the torque ratio, efficiency, and ability of the torque converter to absorb engine torque without allowing the engine to “run away.” This occurs if the torque converter is too small and the pump can&#39;t slow the engine. 
     At low speed ratios, the torque converter works well to allow the engine to rotate while the vehicle is stationary, and to supplement engine torque for increased performance. At speed ratios less than 1, the torque converter is less than 100% efficient. The torque ratio of the torque converter gradually reduces from a high of about 1.8 to 2.2, to a torque ratio of about 1 as the turbine rotational speed approaches the pump rotational speed. The speed ratio when the torque ratio reaches 1 is called the coupling point. At this point, the fluid entering the stator no longer needs to be redirected, and the one way clutch in the stator allows it to rotate in the same direction as the pump and turbine. Because the stator is not redirecting the fluid, torque output from the torque converter is the same as torque input. The entire fluid circuit will rotate as a unit. 
     Peak torque converter efficiency is limited to 92-93% based on losses in the fluid. Therefore torque converter clutch  49  is employed to mechanically connect the torque converter input to the output, improving efficiency to 100%. Clutch piston plate  17  is hydraulically applied when commanded by the transmission controller. Piston plate  17  is sealed to turbine hub  19  at its inner diameter by o-ring  18  and to cover  11  at its outer diameter by friction material ring  51 . These seals create a pressure chamber and force piston plate  17  into engagement with cover  11 . This mechanical connection bypasses the torque converter fluid circuit. 
     The mechanical connection of torque converter clutch  49  transmits many more engine torsional fluctuations to the drivetrain. As the drivetrain is basically a spring-mass system, torsional fluctuations from the engine can excite natural frequencies of the system. A damper is employed to shift the drivetrain natural frequencies out of the driving range. The damper includes springs  15  in series with engine  7  and transmission  8  to lower the effective spring rate of the system, thereby lowering the natural frequency. 
     Torque converter clutch  49  generally comprises four components: piston plate  17 , cover plates  12  and  16 , springs  15 , and flange  13 . Cover plates  12  and  16  transmit torque from piston plate  17  to compression springs  15 . Cover plate wings  52  are formed around springs  15  for axial retention. Torque from piston plate  17  is transmitted to cover plates  12  and  16  through a riveted connection. Cover plates  12  and  16  impart torque to compression springs  15  by contact with an edge of a spring window. Both cover plates work in combination to support the spring on both sides of the spring center axis. Spring force is transmitted to flange  13  by contact with a flange spring window edge. Sometimes the flange also has a rotational tab or slot which engages a portion of the cover plate to prevent over-compression of the springs during high torque events. Torque from flange  13  is transmitted to turbine hub  19  and into transmission input shaft  43 . 
     Energy absorption can be accomplished through friction, sometimes called hysteresis, if desired. Hysteresis includes friction from windup and unwinding of the damper plates, so it is twice the actual friction torque. The hysteresis package generally consists of diaphragm (or Belleville) spring  14  which is placed between flange  13  and one of cover plates  16  to urge flange  13  into contact with the other cover plate  12 . By controlling the amount of force exerted by diaphragm spring  14 , the amount of friction torque can also be controlled. Typical hysteresis values are in the range of 10-30 Nm. 
     Referring to  FIG. 2 , torque converter  10  includes pump  37  and cover  41 . In some cases, the cover and pump are comprised of low carbon steel and formed by a stamping process. Lugs  14  and pilot  15  are welded to the cover. The cover and pump are sealed by a seam weld at  13 . Torque from the engine of a motor vehicle is transferred to the cover through lugs  14 . The torque is then transferred to the pump through the weld connecting the cover and the pump. 
     Stamping the cover and pump are costly and time consuming processes requiring multiple steps. In addition, the steps of welding lugs  14  and pilot  15  are expensive, time consuming, and potentially create contamination. Finally, the seam welding process used to join pump  37  and cover  41  is unstable and creates contamination on the inside of the torque converter. 
     Thus, there is a long-felt need for a torque converter that is easily manufactured without seam welding. Further, there is a long-felt need for a simplified cover that can be simply attached to a pump. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention broadly comprises a torque converter including one of a pump or cover with at least one slot located about a periphery of the one of the pump or cover. The other of the pump or cover includes at least one protrusion located about a periphery of the other of the pump or cover and extending axially through the at least one slot to fasten the pump to the cover. In some aspects, the one of the pump or cover includes an outer surface and an annular radial protrusion disposed about the outer surface proximate the periphery. The slots are disposed in the radial protrusion. In some aspects, the annular radial protrusion is integrally formed with the one of the pump or cover or the annular radial protrusion is formed separately from the one of the pump or cover and fixedly connected to the one of the pump or cover. In some aspects, the torque converter includes a sealing element disposed between the cover and the pump and the sealing element is an o-ring or a gasket. In some aspects, the at least one protrusion is bent radially to clamp the pump and cover. In some aspects, the torque converter includes a ring peripherally located about the one of the pump or cover or an L-ring peripherally located about the other of the pump or cover. In some aspects, the ring or L-ring are in contact with the protrusions. 
     In some aspects, the pump is made of low carbon steel or is formed by a stamping process. In some aspects, the cover is cast from a steel alloy, cast iron, or aluminum. In some aspects, the cover is formed stamping. In some aspects, the cover comprises at least one lug integral to the cover and at least one pilot integral to the cover. 
     The present invention also broadly comprises a method for transferring torque from a drive unit. The method inserts at least one peripherally disposed protrusion for one of a pump or cover of a torque converter through at least one peripherally disposed opening in the other of the pump or cover, bends the at least one protrusion to clamp the cover and the pump, and transfers torque from the cover to the pump through the at least one protrusion. 
     The present invention further broadly comprises a method for sealing a torque converter. The method inserts at least one peripherally disposed protrusion for one of a pump or cover for a torque converter through at least one peripherally disposed opening in the other of the pump or cover, disposes a seal between the cover and the pump, and radially bends the at least one protrusion to compress the cover and the pump against the seal element. 
     The present invention broadly comprises a method of modifying torque converter balance. The method inserts at least one peripherally disposed protrusion for one of a pump or cover for a torque converter through at least one opening in a peripherally disposed ring for the other of the pump or cover, radially bends the at least one protrusion to clamp the cover and the pump, and removes material from an outside of the ring as needed to balance the torque converter. 
     The present invention also broadly comprises a torque converter having a cast cover with at least one slot located about a periphery of the cover, at least one integral lug, and an integral pilot. The converter also includes a stamped pump with at least one protrusion located about a periphery of the pump and a sealing element disposed between the cover and the pump. The at least one protrusion extends axially through the at least one slot and is radially bent to clamp the pump to the cover and to create a seal among the sealing element, the cover and the pump. 
     The present invention further broadly comprises a torque converter including a pump and a cover. The cover includes at least one slot located about a periphery of the cover and the pump includes at least one protrusion located about a periphery of the pump and extending axially through the at least one slot to fasten the cover and pump together. 
     It is an object of the present invention to provide a torque converter with a cover and pump joined without a seam weld. 
     These and other objects and advantages of the present invention will be readily appreciable from the following description of the preferred embodiments of the invention and from the accompanying drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The nature and mode of operation of the present invention will not be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
         FIG. 1  is a general block diagram illustration of power flow in a motor vehicle, intended to help explain the relationship and function of a torque converter in the drive train thereof; 
         FIG. 2  is a cross-sectional view of a prior art torque converter, shown secured to an engine of a motor vehicle; 
         FIG. 3  is a left view of the torque converter shown in  FIG. 2 , taken generally along line  3 - 3  in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the torque converter shown in  FIGS. 2 and 3 , taken generally along line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a first exploded view of the torque converter shown in  FIG. 2 , as shown from the perspective of one viewing the exploded torque converter from the left; 
         FIG. 6  is a second exploded view of the torque converter shown in  FIG. 2 , as shown from the perspective of one viewing the exploded torque converter from the right; 
         FIG. 7A  is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application; 
         FIG. 7B  is a perspective view of an object in the cylindrical coordinate system of  FIG. 7A  demonstrating spatial terminology used in the present application; 
         FIG. 8  is a front perspective view of a present invention torque converter; 
         FIG. 9  is a back perspective view of the cover shown in  FIG. 8 ; 
         FIG. 10  is a front perspective view of the pump shown in  FIG. 8 ; 
         FIG. 11  is a cross-sectional view of the torque converter in  FIG. 8  with internal components removed; 
         FIG. 12   a  is a view of section  12   a  shown in  FIG. 11  with a support ring added; 
         FIG. 12   b  is a perspective view of the support ring shown in  FIG. 12   a;    
         FIG. 13   a  is a view of section  13   a  shown in  FIG. 11  with a support L-ring added; and, 
         FIG. 13   b  is a perspective view of the L-ring shown in  FIG. 13   a.    
     
    
    
     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 aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects. 
     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 aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims. 
     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. 
       FIG. 7A  is a perspective view of cylindrical coordinate system  80  demonstrating spatial terminology used in the present application. The present invention is at least partially described within the context of a cylindrical coordinate system. System  80  has a longitudinal axis  81 , used as the reference for the directional and spatial terms that follow. The adjectives “axial,” “radial,” and “circumferential” are with respect to an orientation parallel to axis  81 , radius  82  (which is orthogonal to axis  81 ), and circumference  83 , respectively. The adjectives “axial,” “radial” and “circumferential” also are regarding orientation parallel to respective planes. To clarify the disposition of the various planes, objects  84 ,  85 , and  86  are used. Surface  87  of object  84  forms an axial plane. That is, axis  81  forms a line along the surface. Surface  88  of object  85  forms a radial plane. That is, radius  82  forms a line along the surface. Surface  89  of object  86  forms a circumferential plane. That is, circumference  83  forms a line along the surface. As a further example, axial movement or disposition is parallel to axis  81 , radial movement or disposition is parallel to radius  82 , and circumferential movement or disposition is parallel to circumference  83 . Rotation is with respect to axis  81 . 
     The adverbs “axially,” “radially,” and “circumferentially” are with respect to an orientation parallel to axis  81 , radius  82 , or circumference  83 , respectively. The adverbs “axially,” “radially,” and “circumferentially” also are regarding orientation parallel to respective planes. 
       FIG. 7B  is a perspective view of object  90  in cylindrical coordinate system  80  of  FIG. 1A  demonstrating spatial terminology used in the present application. Cylindrical object  90  is representative of a cylindrical object in a cylindrical coordinate system and is not intended to limit the present invention is any manner. Object  90  includes axial surface  91 , radial surface  92 , and circumferential surface  93 . Surface  91  is part of an axial plane, surface  92  is part of a radial plane, and surface  93  is part of a circumferential plane. 
       FIG. 8  is a front perspective view of present invention torque converter  100 . 
       FIG. 9  is a back perspective view of cover  102  shown in  FIG. 8 . 
       FIG. 10  is a front perspective view of pump, or impeller,  104  shown in  FIG. 8 . The following should be viewed in light of  FIGS. 8 through 10 . Cover  102  includes slots  106  located about periphery, or edge,  108  of the cover. The slots are formed in annular radial protrusion, or ring,  110 , disposed about outer surface  111  of the cover proximate periphery  108 . In some aspects, the ring is axially displaced from the edge as shown by extension  112 . In some aspects (not shown), the ring is radially aligned with the edge. Pump  104  includes at least one protrusion, or tab,  114  located about periphery, or edge,  116  of the pump. Protrusions  114  extend axially through the slots to fasten the pump to the cover. It should be understood that a present invention torque converter is not limited to the number, size, shape, or configuration of slots and protrusions shown and that other numbers, sizes, shapes, or configurations of slots and protrusions are included in the spirit and scope of the claimed invention. 
       FIG. 11  is a cross-sectional view of torque converter  100  in  FIG. 8  with internal components removed for clarity. The following should be viewed in light of  FIGS. 8 through 11 . Torque converter  100  includes sealing element  118  disposed between the cover and the pump. In some aspects, sealing element  118  is located in a space defined by ring  110 , extension  112 , and tabs  114 . Specifically, notch, or indent,  120  is formed in the cover. Any means known in the art can be used for the sealing element, including but not limited to an o-ring or gasket. Sealing element  118  creates a fluid-tight seal between the cover and pump. 
     To fasten the cover and the pump together, protrusions  114  are radially bent. For example, in an initial stage of assembly, the protrusions extend through the slots and extend axially as shown by dashed lines  122 . Then, the tabs are bent in direction  124  to form the configuration shown in the figures. By bending the tabs, axial pressure is applied to ring  110  by the tabs in direction  126 , drawing the cover and pump together and compressing sealing element  118  between the cover and pump. Thus, a fluid-tight connection is formed without the use of welding and the attendant difficulties noted supra. 
     Cover  102  is arranged for connection to an engine (not shown) in a vehicle (not shown), for example, through lugs  128 . Torque from the engine is transferred to the cover and in turn, the cover transfers the torque to pump  104  via ring  110 . That is, the circumferential edges of the slots contact the circumferential edges of the tabs to transmit the majority of the torque. For example, for torque transmitted to the cover in direction  130 , edges  132  of the slots contact edges  134  of the protrusions. Thus, a torque transfer path is formed between the cover and the pump without the use of welding and the attendant difficulties noted supra. 
     In some aspects, lugs  128  and pilot  136  are integral to the cover, advantageously eliminating the extra fabrication steps associated with the formation and connection of the lugs and pilot to the cover. In some aspects (not shown), the lugs and pilot are formed separately from the cover and fixedly secured to the cover. In some aspects the lugs or pilot are formed by stamping. In some aspects, the cover is formed by stamping. In some aspects, the cover is formed by casting and is made from any castable material known in the art, including but not limited to steel alloys, cast iron, and aluminum. For a cast cover, the lugs and/or pilot can be integrated in the casting. In some aspects, the pump is formed from low carbon steel, for example, to enable the bending of protrusions  114 . In some aspects, the pump is formed by stamping. 
       FIG. 12   a  is a view of section  12   a  shown in  FIG. 11  with support ring  138  added. 
       FIG. 12   b  is a perspective view of support ring  138  shown in  FIG. 12   a a . The following should be viewed in light of  FIGS. 8 through 12   b . In some aspects, support, or reinforcing, ring  138  is used to increase the strength of converter  100 . For example, ring  138  is circumferentially located about the cover proximate ring  110  and the protrusions and connected to the cover. In some aspects, ring  138  contacts protrusions  114 . It should be understood that ring  138  is not limited to any particular size, shape, or configuration. Ring  138  can be attached to cover  102  by any means known in the art, for example, weld  140 . 
       FIG. 13   a  is a view of section  13   a  shown in  FIG. 8  with support L-ring ring  142  added. 
       FIG. 13   b  is a perspective view of support ring  142  shown in  FIG. 13   a . The following should be viewed in light of  FIGS. 8 through 13   b . In some aspects, support, or reinforcing, ring  142  is used to increase the strength of converter  100 . For example, ring  142  is circumferentially located about the pump proximate ring  110  and protrusions  114 . In some aspects, ring  142  contacts ring  110  and protrusions  114 . It should be understood that ring  142  is not limited to any particular size, shape, or configuration. Ring  142  can be attached to pump  104  by any means known in the art, for example, weld  144 . 
     In some aspects, (not shown), the configuration of slots and protrusions is reversed from that shown in the figures. For example, the cover has protrusions located about a periphery and the pump has slots located about a periphery. In general, the description of  FIGS. 8 through 13   a  is applicable to the reversed configuration. 
     In some aspects (not shown), torque converter  100  is balanced by removing material from ring  110 . The material can be removed by any means known in the art, including but not limited to drilling, milling, grinding, turning, and cutting. For example, the material can be removed from the ring on the heavy side of the torque converter. The heavy side is the portion of the torque converter which has increased weight and creates imbalance. 
     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.