Abstract:
A hydraulic torque transferring assembly comprising a shell, at least one blade installed in the shell, the blade having an inlet for receiving a flow of fluid, wherein the blade includes a notch, wherein the notch is operatively arranged to reduce a pressure that the flow of fluid exerts on the inlet, and wherein the assembly is for a turbine or an impeller in a torque converter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/263,043, filed Nov. 20, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention broadly relates to torque converters, more specifically to blades for impeller and turbine assemblies in torque converters, and even more particularly to a blade having a notch on an inlet for use in an impeller or turbine assembly of a torque converter. 
       BACKGROUND OF THE INVENTION 
       [0003]    Torque converters are well known in the art, typically including at least an impeller and a turbine for transferring torque between an engine and a transmission in a vehicle. As technology advances, higher capacity torque converters become possible without increasing the size of the converter. Likewise, smaller torque converters are possible, which have capacities comparable to previous, larger designs. 
         [0004]    However, these smaller torque converters and other torque converter designs can lead to unique torque converter characteristics, which particularly can change the interaction between the turbine or impeller and the working fluid. For example, the entrance angle of the fluid into the impeller may depend at least partially on the speed ratio, interrelationship between the impeller, the stator, and the turbine, or some other characteristic unique to the particular torque converter design. Especially at low speed ratios, the working fluid is flowing in a direction that is not aligned with the direction of rotation of the blades, which increases the pressure on the inlet of each blade. That is, particularly at low speed ratios, a change in fluid flow direction generally takes place at the inlet of the impeller blades. Consequently, the pressure causes stresses in the joints between the blades and the shell. The stresses are generally greatest in the joint proximate to the tip or leading edge of the blade. If the stresses become too high, the joint may fail, damaging the torque converter. 
         [0005]    U.S. Pat. No. 5,334,112 (Nogle et al.) shows a turbine blade having a notch at its outlet. Japanese Patent Publication No. JP11193858 (Osamu et al.) also discloses a turbine blade having a notch at its outlet. The notches are included to stop ringing or other noise due to vibration of the blades at a resonance frequency of the blades by altering how the fluid is expelled from the turbine. Heretofore, similar notches have not been used in impeller blades, nor have they been used at the inlet of either turbine or impeller blades. U.S. Pat. No. 6,226,985 (Sasse et al.) teaches long narrow slits in the inlet and outlets of impeller and turbine blades, but these slits are not suitable for reducing pressure on the inlets of the blades, but instead to bifurcate the blades into two different working profiles. 
         [0006]    Thus, what is needed a means for reducing the pressure on the inlet of a torque converter blade, particularly if the blade is not brazed or affixed well, or the pressure on the blade is unusually high to some other unique characteristic of the torque converter, such as the interrelationship between the impeller, turbine, and stator. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention broadly comprises a hydraulic torque transferring assembly comprising a shell, at least one blade installed in the shell, the blade having an inlet for receiving a flow of fluid, wherein the inlet includes a notch, and wherein the notch is operatively arranged to reduce a pressure that the flow of fluid exerts on the inlet. In one embodiment, a turbine comprises the hydraulic torque transferring assembly. In one embodiment, an impeller comprises the hydraulic torque transferring assembly. In one embodiment the notch occupies approximately 40-80% of a total inlet length of the blade. In one embodiment, the notch has a depth, and the depth of the notch is a distance of approximately 30-50% of the total inlet length of the blade. In one embodiment, the notch is semicircular or arcuate in shape. In one embodiment, the blade is affixed to the shell by brazing. 
         [0008]    The current invention also broadly comprises a torque converter including the torque transferring assembly. In one embodiment, the torque converter further includes a turbine, wherein the turbine comprises the hydraulic torque transferring assembly. In one embodiment, the torque converter further includes an impeller, wherein the impeller comprises the hydraulic torque transferring assembly. In one embodiment, the inlet has a length, and the notch occupies approximately 40-80% of the length along the inlet. In one embodiment, the inlet has a length, the notch has a depth, and the depth of the notch is a distance of approximately 30-50% of the length. In one embodiment, the notch is semicircular or arcuate in shape. In one embodiment, the blade is affixed to the shell by brazing. 
         [0009]    The current invention also broadly comprises a blade for a torque converter including an inlet for receiving a flow of fluid, a notch in the inlet operatively arranged to reduce a pressure exerted on the input edge of the blade by the flow of fluid. In one embodiment, a turbine comprises at least one such notched blade. In one embodiment, an impeller including at least one such notched blade. In one embodiment, the inlet has a length, and the notch occupies approximately 40-80% of the length along the inlet. In one embodiment, the inlet has a length, the notch has a depth, and the depth of the notch is a distance of approximately 30-50% of the length. In one embodiment, the notch is semicircular or arcuate in shape. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    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: 
           [0011]      FIG. 1  is a cross-sectional view of a torque converter having an impeller and a turbine; 
           [0012]      FIG. 2  is a perspective exploded view of an impeller assembly and a turbine assembly; 
           [0013]      FIG. 3  is a front view of an impeller assembly including a plurality of notched blades; 
           [0014]      FIG. 4  is a cross-sectional view of the impeller assembly generally taken along line  4 - 4  in  FIG. 3 ; 
           [0015]      FIG. 5  is a perspective view of a notched blade for a turbine; and, 
           [0016]      FIG. 6  is a perspective view of a notched blade for an impeller. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    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. 
         [0018]    Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and 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. 
         [0019]    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. 
         [0020]    Referring now to the figures,  FIG. 1  shows torque converter  10  having impeller or pump  12  and turbine  14 , specifically for transferring torque between an engine and a transmission of an automobile. Impeller  12  is generally defined by impeller shell  16 , while turbine  14  is generally defined by turbine shell  18 . Impeller blades, such as blades  100 , are mountable between shell  16  and ring  20 , while turbine blades, such as blades  200 , are mountable between shell  18  and ring  22 .  FIG. 2  shows this general arrangement with impeller blades  24  between ring  20  and shell  16 , and turbine blades  26  between ring  22  and shell  18 . 
         [0021]    Impeller assembly  50  is shown in  FIGS. 3 and 4 . Assembly  50  includes shell  52  which includes a plurality of impeller blades  100  affixed therein, which blades include notches  102 . Blades  100  are additionally supported by ring  54  of the assembly via tabs  104 . Impeller blade  100  is shown in more detail in  FIG. 6 , while turbine blade  200  is shown in  FIG. 5 . Blade  100  receives the fluid at inlet  106 ; the fluid is directed by the angle of the blade in the impeller, and expelled from the blade at output edge  108  in a direction toward the turbine, where the fluid is received by inlet  206  and directed out of the turbine at outlet  208 . By inlet it is meant the portion of the blade that receives the working fluid. That is, the inlet primarily comprises the leading edge or tip of the blade, but may also be generally defined to include a portion of surface of the blade proximate to the leading edge. 
         [0022]    While other methods of affixing blades  100  to the impeller shell are possible, a common technique is by brazing. For example, in one embodiment, surface  114  of blade  100  is brazed to shell  16  and surface  112  is brazed to ring  20 . Likewise, in one embodiment, surface  214  of blade  200  is brazed to shell  18 , while surface  112  is brazed to ring  22 . In the embodiment shown, blade  100  includes tabs  110  about outer edge  114  to assist in securing to the impeller shell, while blade  200  includes tabs  210  about outer edge  214  to assist in securing to the turbine shell. 
         [0023]    Notch  102  in blade  100  redistributes the pressure on the inlet, particularly to reduce the stresses in the joints which affix the blade to the shell. Each notch  102  generally divides the inlet into inlet portions  106 A and  106 B. Advantageously, the notch reduces the total force on the inlet, and the force is concentrated near brazed edges  112  and  114 . That is, instead of force applying across an entire tip or leading edge of a blade, the force is concentrated on only the ends of the leading edge. Since the force is redistributed to the inlet portions proximate to the brazed or affixed edges, the joints at these locations are better able to withstand the forces than if the fluid acted on a typical blade which did not include a notch. Advantageously, this lower pressure enables poorer quality braze joints, or typical joints in a torque converter having a unique characteristic that results in relatively large pressures, to sufficiently withstand the pressure exerted by the working fluid without failure of the joints. It should be appreciated that by reducing the pressure on the inlet, notch  102  reduces the failure rate of blades secured to the impeller shell by means other than brazing, although the notches are particularly beneficial in impellers having brazed joints. 
         [0024]    In the embodiment shown, inlet  106  is defined in two portions on either side of notch  102  along a distance designated L 2 . Length L 2  is generally referred to as the total inlet length, and is defined between the inner support ring and the shell, such as ring  20  and shell  16 . That is, inlet length L 2  is generally the length that would define the tip, leading edge, or inlet of the blade if it did not include a notch. Notch  102  occupies a distance designated L 1  of the total distance L 2  of the blade. In preferred embodiments, the notch occupies a substantial portion of the total inlet length. For example, it has been found that satisfactory results can generally be achieved with length L 1  of notch  102  occupying between approximately 40-80% of total inlet length L 2 , although other ratios may work satisfactorily. 
         [0025]    Notch  102  also has a depth designated D 1 , of which depth the notch extends into blade  100 . In the embodiment shown, notch  102  is semicircular or arcuate in shape, so distance D 2  is equal to the radius, or a portion of the radius of the semicircle. However, it should be appreciated that other shapes could be used to define notch  102 . In specific preferred embodiments, depth D 1  is a distance equal to approximately 30-50% of total inlet length L 2  to ensure sufficient redistribution and reduction of the pressure on the inlet of the blade, although it should be appreciated that other values may work satisfactorily. 
         [0026]    Turbine blade  200  is shown in  FIG. 5 . Generally, turbine blades resemble impeller blades in shape and size, since both the turbine blades and impeller blades are arranged for directing the flow of fluid through the torque converter. Blade  200  may include tab  204  for securing the blade, for example, to a turbine assembly ring, such as ring  22 , and tabs  210  for securing to a turbine shell, such as shell  18 . The turbine blades are also typically affixed to the shell by brazing, although other methods are known in the art. 
         [0027]    In operation of the torque converter, the working fluid expelled from the impeller is received by the turbine. Accordingly, if impeller assembly  12  includes blades  100  and turbine assembly  14  includes blades  200 , the fluid expelled by blades  100  at outlet  108  is received by turbine assembly  14 , specifically at inlet  206  of blades  200 . Like impeller blade  100 , turbine blade  200  includes notch  202 . Notch  202  is similarly included to divide the inlet into portions  206 A and  206 B, for reducing the total pressure exerted on the inlet portion of blade  200  by the working fluid, and concentrate the forces exerted by the working fluid on the portions near brazed edges  212  and  214 . The working fluid is then transferred along blade  200  to outlet  208 , where it is expelled, typically to a stator of the torque converter or back into the impeller. 
         [0028]    In the embodiment shown, inlet  206  is defined along a distance designated L 4 . Distance L 2  is generally referred to as the total inlet length, and is defined between the inner assembly ring, such as ring  22  and the shell, such as shell  18 . That is, inlet length L 4  is generally the length of the tip, leading edge, or inlet of the blade if it did not include a notch. Notch  202  occupies a distance designated L 3  of the total length L 4 . In preferred embodiments, the notch occupies a substantial portion of the total inlet length. For example, it has been found that satisfactory results can generally be achieved with length L 3  of notch  202  occupying between approximately 40-80% of total inlet length L 4 , although other ratios may work satisfactorily. 
         [0029]    Notch  202  also has a depth designated D 2 , of which depth the notch extends into blade  200 . In the embodiment shown, notch  202  is semicircular or arcuate in shape, so distance D 2  is equal to the radius, or a portion of the radius of the semicircle. However, it should be appreciated that other shapes could be used to define notch  202 . In specific preferred embodiments, depth D 2  is a distance equal to approximately 30-50% of length L 4  of the inlet to ensure sufficient redistribution of the pressure exerted by the working fluid, although it should be appreciated that other values may also work satisfactorily. 
         [0030]    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.