Abstract:
An assembly for a torque converter including a first component, a second component non-rotatably secured to the first component by a connection member, wherein a seal is arranged between the first and second components, and the connect member extends through the seal, and wherein the seal is made from a cellulose-based material, wherein the first and second components at least partially define a first chamber and a second chamber, and wherein the seal separates the first chamber from the second chamber in a substantially fluid-tight seal manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/425,422 filed Dec. 21, 2010 which application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention broadly relates to torque converters, more specifically to clutches in torque converters, and even more particularly to a fluid-tight seal for improved operation of a clutch in a torque converter. 
     BACKGROUND OF THE INVENTION 
     Torque converters are well known in the art. Some torque converters, such as torque converters having a so-called three-pass clutch lockup design, include a clutch plate retainer that is attached to the cover of the torque converter. The retainer carries and transfers torque to clutch plates. The attachment of such retainers in prior art torque converters involved welding the retainer to the cover or attaching the retainer without any special sealing element or process. For example, see U.S. Pat. No. 5,964,329 (Kawaguchi et al.) and United States Patent Publication 2007/0251788 (Heck et al.), which Patent and Patent Publication are hereby incorporated by reference in their entireties. Attaching the retainer to the cover without any additional sealing element enables leakage between the cover and clutch plate retainer and results in poor performance of the clutch, which relies on a pressure difference between two pressure chambers on opposite sides of the piston. Welding reliably forms a fluid-tight seal, but it is expensive and may warp or deform the cover, or create spatter or other contaminants that degrade the operation of the torque converter and are difficult to remove. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention broadly comprises an assembly for a torque converter including a first component, a second component non-rotatably secured to the first component by a connection member, wherein a seal is arranged between the first and second components, and the connect member extends through the seal, and wherein the seal is made from a cellulose-based material, wherein the first and second components at least partially define a first chamber and a second chamber, and wherein the seal separates the first chamber from the second chamber in a substantially fluid-tight seal manner. 
     In one embodiment, the seal is formed from friction material for a wet-running clutch. In one embodiment, the seal is impregnated by resin. In one embodiment, the first component is a cover for the torque converter and the second component is a retainer for carrying plates of a clutch. In one embodiment, the connection member is an extruded rivet. In one embodiment, the first and second chambers are formed on opposite sides of a piston of the torque converter. 
     These and other objects and advantages of the present invention will be readily appreciable from the following description of preferred embodiments of the invention and from the accompanying drawings and 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 cross-sectional view of a torque converter having a substantially fluid-tight seal formed between a cover and a clutch carrier; and, 
         FIG. 2  is an enlarged view of the components forming the substantially fluid-tight seal. 
     
    
    
     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. It is also understood that any reference to axial or radial directions or properties is made with respect to the axis of rotation shown in the drawings, located generally along the bottom of  FIG. 1 . 
     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. 
     Referring now to the figures,  FIG. 1  shows torque converter  10  arranged, for example, with cover  12  connected to an engine or other torsional input (not shown), the torque converter also having impeller  14  connected to the cover, turbine  16  having shell  17 , stator  18 , and vibration damper  20  for hydraulically transferring torque through the torque converter. These components are shown for purposes of discussion, and could be replaced by any type or style of cover, impeller, turbine, stator, and/or vibration damper known in the art, and in some embodiments, some of these components may not even be included. 
     Torque converter  10  additionally includes lockup clutch  22  for mechanically coupling a transmission input shaft (not shown) and/or output flange  23  of damper  20  to cover  12  and/or the torsional input. Piston  24  is axially moveable in the torque converter and provided for engagement of clutch  22 . Retainer  26  is included to act as a carrier for the plates of clutch  22 , such as plates  25 . The other clutch plate shown in  FIG. 1  is connected to cover plates  27  of damper  20 . Connection member  28  is shown non-rotatably attaching retainer  26  to cover  12 . That is, the connection member is included to transfer torque between the cover and clutch plate retainer. In  FIG. 1 , connection member  28  is shown particularly as an extruded rivet, although it should be understood that the connection member could take other forms, such as a bolt or the like. 
     As can be seen most clearly in  FIG. 2 , seal  30  is provided between cover  12  and retainer  26 . Seal  30  is provided because, in order for clutch  22  to operate properly, a pressure differential must be creatable between the fluid chambers on opposite sides of piston  24 . That is, chamber  32  must be sealed in a fluid-tight manner from chamber  34 . Chamber  32  is generally a main operating chamber for the torus of the torque converter, while chamber  34  is an apply chamber for moving the piston axially toward clutch  22  for closing the clutch. As discussed above, welding retainer  26  to cover  12  would provide a good seal, but would be very costly and may result in warping or the creation of spatter or other contaminants. If no special sealing element or process is used, then too much leakage would occur between chambers  32  and  34 , and the torque converter would fail to meet the increasingly precise requirements of modern torque converter clutches. 
     The seal is provided as a thin, ring shaped component that surrounds connection member  28  for preventing the leakage of operating fluid, such as oil, in the generally radial direction between the retainer and the cover. In other words, the connection members extend through the seal for clamping the seal between the cover and the clutch plate retainer. The seal is formed from paper or cellulose-based clutch friction material. That is, many torque converters include clutches that include a special friction material for providing improved engagement of the clutch. One type of friction material is paper or cellulose-based, wherein the paper or cellulose is usually impregnated with a resin, such as a phenolic resin, or other bonding agent. Advantageously, this friction material is suitable for operating in the harsh environment of a torque converter. For example, unlike rubber seals, cellulose-based friction material is capable of withstanding immersion in high temperature oil without degradation. It is also capable of withstanding large compressive or axial forces. Furthermore, the cellulose-based material is known to absorb oil, which may result in a slight swelling of the seal for providing an even tighter seal between the cover and retainer. Because the material can absorb oil, there may be a very slow seepage of oil through the seal, but it would not be enough to affect the performance of the clutch. Heretofore, clutch friction material has only been used for coupling rotating components together. According to the current invention, friction material for a clutch is used as to form a fluid-tight seal between two non-rotatable components. 
     Other clutch friction materials would not work similarly as a seal. For example, too much leakage would occur from using carbon-based woven friction materials. Additionally, typical rubber sealing materials would not work because they can not withstand prolonged immersion in high temperature oil, and specialized seals are prohibitively expensive. 
     It should be understood, particularly with respect to  FIG. 2 , that any two components of a torque converter could be sealed according to the current invention in lieu of welding or the like. For example, the cover, turbine shell, piston, or damper components could be sealed to clutch plates, retainers, drive plates, etc., according to the current invention. 
     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.