Abstract:
A blade assembly for a torque converter including a shell with an inner surface and a plurality of blades attached to the shell by brazing. Each blade has a first surface for guiding a fluid in the torque converter and a second surface substantially parallel to the inner surface. The blades may include sheet steel and may be made by stamping. In an example embodiment of the invention, each blade includes at least one tab, the shell comprises a plurality of slots or indents, and the at least one tab is disposed in a respective slot or indent. The shell may be an outer shell or a core ring for a pump or turbine for the torque converter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/288,522 filed Dec. 21, 2009. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to a torque converter, and more specifically to a blade assembly with improved braze joint strength for the torque converter. 
     BACKGROUND OF THE INVENTION 
     Torque converters include shells and blades to direct fluid flow. Commonly assigned United States patent application publication number 2008/0308373 describes a blade surface with tabs arranged to conform to an inner surface of the shell to provide a fluid seal. United States patent application publication number 2009/0000289 describes a blade with an edge shaped so that at least a portion of the edge can be inserted into a depression in the internal surface of the shell with which it is to be connected. U.S. Pat. No. 5,794,436 assigned to Aisin AW Co., Ltd., describes a pump impeller and a turbine runner with inclined blades having edge portions bent to form right angle connections to shells and cores of the pump impeller and the turbine runner. 
     The following description is made with reference to  2 - 4 .  FIG. 2  is a back view of a prior art impeller assembly shown without brazing for clarity.  FIG. 3  is a partial section view of the impeller assembly of  FIG. 2  taken generally along line  3 - 3  in  FIG. 2 .  FIG. 4  is a detail view of encircled region  4  in  FIG. 3  shown with brazing. Prior art blade  116  is attached to shells  112  and  114  by braze material. Blade  116  may be attached to shell  112  by braze material  130  and  131 , for example. Materials  130  and  131  may be a copper paste melted and bonded to blade  116  and shells  112  and  114  by brazing in a brazing furnace, although other methods and processes are possible. As is known in the art, the strength of a brazing joint is dependent on the gap filled by the braze material. Smaller gaps are desirable as they result in a stronger joint. 
     A joint area of prior art blade  116  to shell  112  includes gaps  132  and  133  filled by braze material  130  and  131 , respectively. Gap  133  is considerably larger than gap  132 . Blade thickness  134  is measured between fluid guiding surface  140  and parallel surface  141 . As can be appreciated from  FIG. 4 , as blade thickness  134  is increased or blade to shell angle  136  is decreased, height of surface  138  from shell  112  is increased, thereby increasing gap  133 . 
     BRIEF SUMMARY OF THE INVENTION 
     Example aspects of the present invention broadly comprise a blade assembly for a torque converter including a shell with an inner surface and a plurality of blades attached to the shell by brazing. Each blade has a first surface for guiding a fluid in the torque converter and a second surface substantially parallel to the inner surface. The blades may include sheet steel and may be made by stamping. In an example embodiment of the invention, each blade includes at least one tab, the shell includes a plurality of slots or indents, and the at least one tab is disposed in a respective slot or indent. The shell may be an outer shell or a core ring for a pump or turbine for the torque converter. 
     In an example embodiment of the invention, the second surface is substantially orthogonal to the first surface. In some example embodiments of the invention, each blade includes an end portion including a portion of the first surface, the second surface, and a third surface, and the second surface forms a chamfer between the first and third surfaces. In an example embodiment of the invention, each blade includes at least one tab extending from the end portion, the shell includes a plurality of slots or indents, and the at least one tab is disposed in a respective slot or indent. 
     Other example aspects of the invention broadly comprise a blade assembly for a torque converter including a shell with an inner surface and a plurality of blades attached to the shell by brazing. Each blade in the plurality of blades has a first surface for guiding fluid in the torque converter and a second surface parallel to the first surface. The first and second surfaces define a thickness for the blade. Each blade also includes an end portion with respective portions of the first and second surfaces, a coined surface extending from the first surface and substantially parallel to the inner surface, and a third surface connecting the coined surface to the second surface. 
     In an example embodiment of the invention, a juncture of the third and coined surfaces is about midway through the thickness of said each blade. In an example embodiment of the invention, an angle measured between the first surface and the coined surface is substantially equal to an angle measured between the first surface and the shell. 
     Other example aspects of the invention broadly comprise a blade assembly for a torque converter including a shell with an inner surface and a plurality of blades attached to the shell by brazing. Each of the blades in the plurality of blades has a first surface for guiding fluid in the torque converter, a second surface offset from and parallel to the first surface, and a third surface parallel to the inner surface. The third surface connects an edge of the first surface with an edge of the second surface. In an example embodiment of the invention, each blade is bent proximate the shell. 
    
    
     
       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. 1A  is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application; 
         FIG. 1B  is a perspective view of an object in the cylindrical coordinate system of  FIG. 1A  demonstrating spatial terminology used in the present application; 
         FIG. 2  is a back view of a prior art impeller assembly shown without brazing for clarity; 
         FIG. 3  is a partial section view of the impeller assembly of  FIG. 2  taken generally along line  3 - 3  in  FIG. 2 ; 
         FIG. 4  is a detail view of encircled region  4  in  FIG. 3  shown with brazing; 
         FIG. 5  is a perspective view of an impeller assembly for a torque converter, according to an example embodiment of the invention; 
         FIG. 6  is a back view of the impeller assembly of  FIG. 5  shown without brazing for clarity; 
         FIG. 7  is a section view of the impeller assembly of  FIG. 5  taken generally along line  7 - 7  in  FIG. 6 ; 
         FIG. 8  is a partial section view of the impeller assembly of  FIG. 5  taken generally along line  8 - 8  in  FIG. 6 ; 
         FIG. 9A  is a detail view of encircled region  9 A in  FIG. 8  showing a chamfered blade with brazing, according to an example aspect of the invention; 
         FIG. 9B  is an alternative embodiment of encircled region  9 A in  FIG. 8  showing a bent and chamfered blade with brazing, according to an example aspect of the invention; 
         FIG. 9C  is an alternative embodiment of encircled region  9 A in  FIG. 8  showing a bent blade with brazing, according to an example aspect of the invention; 
         FIG. 9D  is an alternative embodiment of encircled region  9 A in  FIG. 8  showing a flattened blade with brazing, according to an example aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At the outset, it should be appreciated that like drawing numbers appearing in different drawing views identify identical, or functionally similar, structural elements. Furthermore, it is understood that this invention is not limited only to the particular embodiments, methodology, materials and modifications described herein, 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 following example methods, devices, and materials are now described. 
       FIG. 1A  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. 1B  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 in 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. 
     The following description is made with reference to  FIGS. 5-8 .  FIG. 5  is a perspective view of an impeller assembly for a torque converter.  FIG. 6  is a back view of the impeller assembly of  FIG. 5  shown without brazing for clarity.  FIG. 7  is a section view of the impeller assembly of  FIG. 5  taken generally along line  7 - 7  in  FIG. 6 .  FIG. 8  is a partial section view of the impeller assembly of  FIG. 5  taken generally along line  8 - 8  in  FIG. 6 . Impeller assembly  10  generally includes blade assembly  11  having shells  12  and  14 , and blades  16 . In an example embodiment of the invention, shell  12  is an outer shell and shell  14  is a core ring for impeller assembly  10 . Shell  12  includes inner surface  13  and shell  14  includes inner surface  15 . Impeller assembly  10  also includes impeller hub  18 . Although impeller hub  18  is shown as a separate component fixedly connected to outer shell  12  at weld  20 , in some embodiments of the invention (not shown), hub  18  may be integral to shell  12 . 
     Shell  12  includes indents  22  for receiving outside tabs  24  of blades  16 . Core ring  14  includes slots  26  for receiving inside tabs  28  of blades  16 . Although a particular number of indents  22  and outside tabs  24 , and slots  26  and inside tabs  28 , are shown, any number of indents, slots, and tabs may be present so long as blade  16  is properly positioned and retained in shells  12  and  14 . Furthermore, in some example embodiments of the invention (not shown), shell  12  may be a shell for a turbine assembly (not shown) for the torque converter comprising slots (not shown) in place of indents  22 . In an example embodiment of the invention, blades  16  are made from sheet steel in a stamping process. 
     The following description is made with reference to  FIG. 9A .  FIG. 9A  is a detail view of encircled region  9 A in  FIG. 8  showing a chamfered blade with brazing, according to an example aspect of the invention. Blade  116  is attached to shells  12  and  14  by braze material. Blade  16 A may be attached to shell  12  by braze material  30 A and  31 A, for example. 
     In some example embodiments of the invention, blade  16 A includes surface  40 A for guiding the fluid in the torque converter. Blade  16 A also comprises surface  38 A and coined, or chamfered, surface  42 A forming end portion  44 A. Surface  40 A and end portion  44 A share common edge  46 A. Coined surface  42 A is arranged to be substantially parallel to shell  12 . That is, angle  36  measured between surface  40 A and shell  12  is substantially equal to an angle measured between surface  40 A and coined surface  42 A. 
     In an example embodiment of the invention shown in  FIG. 9A , coined surface  42 B forms a chamfer between surface  40 A and surface  38 A. Blade thickness  34  is measured between fluid guiding surface  40 A and parallel surface  41 A. Coined surface  42 A terminates on surface  38 A. In an example embodiment of the invention, coined surface  42 A terminates on surface  38 A approximately midway through thickness  34 , or midway between surfaces  40 A and  41 A. That is, a juncture of the surfaces  38 A and  42 A is about midway through thickness  34  of blade  16 A. A joint area of blade  16 A to shell  12  includes gaps  32 A and  33 A filled by braze material  30 A and  31 A, respectively. As can be appreciated from the figures, gap  33 A in FIG.  9 A is less than gap  133  in  FIG. 4  for blade  16 A with thickness  34  equal to thickness  134  and angle  36  equal to thickness  136 . As stated supra, smaller gaps  32 A and  33 A provide improved joint strength for blade  16 A. 
     The following description is made with reference to  FIG. 9B .  FIG. 9B  is an alternative embodiment of encircled region  9 A in  FIG. 8  showing a bent and chamfered blade with brazing, according to an example aspect of the invention. Blade  16 B is attached to shells  12  and  14  by braze material. Blade  16 B may be attached to shell  12  by braze material  30 B and  31 B, for example. 
     In some example embodiments of the invention, blade  16 B includes surface  40 B for guiding the fluid in the torque converter. Blade  16 B also comprises coined, or chamfered, surface  42 B forming end portion  44 B. Surface  40 B and end portion  44 B share common edge  46 B. Coined surface  42 B is arranged to be substantially parallel to shell  12 . That is, angle  36  measured between surface  40 B and shell  12  is substantially equal to an angle measured between surface  40 B and coined surface  42 B. Coined surface  42 B is not orthogonal to surface  40 B, so surface  42 B is longer the surface  138  in  FIG. 4 . 
     In an example embodiment of the invention shown in  FIG. 9B , surface  40 B includes bent portion  48 B proximate shell  12 . A joint area of blade  16 B to shell  12  includes gaps  32 B and  33 B filled by braze material  30 B and  31 B, respectively. Blade thickness  34  is measured between fluid guiding surface  40 B and parallel surface  41 B. As can be appreciated from  FIG. 9B , gaps  32 B and  33 B in  FIG. 9B  are less than gaps  132  and  133  in  FIG. 4  for blade  16 B with thickness  34  equal to thickness  134  and angle  36  equal to angle  136 . 
     The following description is made with reference to  FIG. 9C .  FIG. 9C  is an alternative embodiment of encircled region  9 A in  FIG. 8  showing a bent blade with brazing, according to an example aspect of the invention. Blade  16 C is attached to shells  12  and  14  by braze material. Blade  16 C may be attached to shell  12  by braze material  30 C and  31 C, for example. 
     In some example embodiments of the invention, blade  16 C includes surface  40 C for guiding the fluid in the torque converter. Blade  16 C also comprises surface  38 C forming end portion  44 C. Surface  40 C and end portion  44 C share common edge  46 C. Surface  38 C is arranged to be substantially parallel to shell  12 . That is, angle  36  measured between surface  40 C and shell  12  is substantially equal to an angle measured between surface  40 C and surface  38 C. 
     In an example embodiment of the invention shown in  FIG. 9C , surface  40 D includes bent portion  48 C proximate shell  12  so that surface  38 C is substantially orthogonal to bent portion  48 C of surface  40 C. A joint area of blade  16 C to shell  12  includes gaps  32 C and  33 C filled by braze material  30 C and  31 C, respectively. Blade thickness  34  is measured between fluid guiding surface  40 C and parallel surface  41 C. As can be appreciated from  FIG. 9C , gaps  32 C and  33 C in  FIG. 9C  are less than gap  132  and  133  in  FIG. 4  for blade  16 C with thickness  34  equal to thickness  134  and angle  36  equal to thickness  136 . 
     The following description is made with reference to  FIG. 9D .  FIG. 9D  is an alternative embodiment of encircled region  9 A in  FIG. 8  showing a flattened blade with brazing, according to an example aspect of the invention. Blade  16 D is attached to shells  12  and  14  by braze material. Blade  16 D may be attached to shell  12  by braze material  30 D and  31 D, for example. 
     In some example embodiments of the invention, blade  16 E includes surface  40 D for guiding the fluid in the torque converter. Blade  16 D also comprises surface  38 D forming end portion  44 D. Surface  40 D and end portion  44 D share common edge  46 D. Surface  38 D is arranged to be substantially perpendicular to shell  12 . 
     In an example embodiment of the invention shown in  FIG. 9D , surface  40 D includes bent portion  48 D proximate shell  12 . A joint area of blade  16 D to shell  12  includes gaps  32 D and  33 D filled by braze material  30 D and  31 D, respectively. Blade thickness  34  is measured between fluid guiding surface  40 D and parallel surface  41 D. Angle  36  is measured between surface  40 D and shell  12 . As can be appreciated from the  FIG. 9D , gap  33 D in  FIG. 9D  is less than gap  133  in  FIG. 4  for blade  16 D with thickness  34  equal to thickness  134  and angle  36  equal to angle  136 . 
     Although the foregoing descriptions referred to gaps and angles with respect to shell  12 , it can be appreciated that the same gaps and angles are present in and the methods described for reducing the gaps would be equally applicable to the joint between blade  16  and shell  14 . As stated supra, shell  12  may be an impeller shell or turbine shell for the torque converter, while shell  14  may be a core ring for the torque converter. Blade tabs  24  joining blade  16  to the impeller shell are typically disposed in indents  22 , while blade tabs (not shown) joining blade  16  to the turbine shell and tabs  28  joining blade  16  to the core ring are typically disposed in slots and formed to hold blade  16 . 
     Of course, changes and modifications to the above examples of the invention should be readily apparent to those having ordinary skill in the art, without departing from the spirit or scope of the invention as claimed. Although the invention is described by reference to specific preferred and/or example embodiments, it is clear that variations can be made without departing from the scope or spirit of the invention as claimed.