Abstract:
The invention broadly comprises a torque converter including: a core ring; a turbine blade connected to the ring and having a perimeter with a segment facing an outer surface of the ring and disposed proximate the outer surface; and joining material fixedly connecting less than the entirety of the segment to the outer surface. The segment is fixedly connected to reduce resonance in the turbine. In some aspects, the ring includes an inner surface oppositely disposed from the outer surface and an open path between the surfaces. The present invention broadly comprises a notched turbine blade and a core ring with a discontinuity in an outer surface arranged to block capillary action for flowable joining material disposed in an interface between a turbine blade installed on the ring and the outer surface. The invention also broadly comprises a method for controlling resonance of a turbine in a 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. 60/812,021, filed Jun. 8, 2006. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to a turbine for a torque converter, and, more particularly, to a turbine with blades partially brazed to a core ring for the turbine to reduce noise caused by the combination of mechanical and fluid dynamic properties of the turbine sub-assembly. 
     BACKGROUND OF THE INVENTION 
     It is well known that a torque converter is used to transmit torque from an engine to a transmission of a motor vehicle.  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. 
     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. 
     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 high speed ratios, the torque converter is less 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. Torque ratio of 1 is called the coupling point. At this point, the fluid entering the stator no longer needs 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. 
     Maximum 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 near 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 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. 
     Torque converter turbines are generally formed with blades disposed between a core ring and a turbine shell. The blades direct fluid from the inlet of the turbine, which is proximate the outer circumference of turbine, to the outlet of the turbine, which is proximate the inner circumference of the turbine. Blades are typically attached to the core ring with tabs extending from the blade that bent after they are inserted into slots in the core ring. A channel or gap is present at the interface between the blade and the surface of the core ring. Durability and performance of the turbine can be enhanced by applying a joining material along the interface. The joining material can be various materials, but typically, due to the relatively narrow spaces between the blades and the surfaces of the shell and core ring, materials capable of flow through capillary action are used. Typically, the joining material of choice is brazing material such as braze paste, but other alternatives can be used. The application of joining material increases the rigidity of the torque converter turbine by bonding the edges of the blades that face the core ring to surfaces of the core ring. The joining material essentially produces a turbine that is single solid unit formed from three separate components. 
     Turbines assemblies of the type described above can experience noise caused by the combination of mechanical and fluid dynamic properties of the turbine sub-assembly. Noise generated in a turbine subassembly can be significant enough to irritate drivers. 
     Thus, there is a long-felt need to provide a turbine that has either reduced stiffness, reduced resonance, and/or a change in natural frequency that will lead to a reduction in noise produced by the torque converter without reducing the performance and durability of the turbine. 
     SUMMARY OF THE INVENTION 
     The invention broadly comprises a torque converter including: a core ring; a turbine blade connected to the core ring and having a perimeter where the perimeter includes a segment facing an outer surface of the core ring and is disposed proximate the outer surface. A joining material is used to fixedly connect less a portion of the segment but less than the entirety of the segment to the outer surface of the core ring. The segment is fixedly connected to reduce resonance in the turbine. 
     In some aspects, the core ring includes an inner surface oppositely disposed with respect to the outer surface and at least one open path between the inner and outer surfaces. The at least one open path is aligned with the segment and the alignment is orthogonal to the outer surface of the core ring. The at least one open path is arranged to block capillary action along the segment. In some aspects, the core ring includes first and second slots, the blade includes first and second tabs inserted through the first and second slots, respectively, and at least one of the first or second slots includes the at least one open path. In some aspects, each of the first or second slots includes the at least one open path. 
     In some aspects, the core ring includes first and second slots, the blade includes first and second tabs inserted through the first and second slots, respectively, and the at least one open path is disposed between the first and second slots and separate from the first and second slots. In some aspects, the core ring includes first and second slots, the blade includes first and second tabs inserted through the first and second slots, respectively, and the segment includes a notch disposed between the first and second tabs. The notch is arranged to block capillary action along the segment. In some aspects, the joining material is a brazing material or a welding material. 
     The invention further broadly comprises a core ring for a torque converter including an outer surface and a discontinuity in said outer surface. The discontinuity is arranged to block capillary action for flowable joining material disposed in an interface between a turbine blade installed on the core ring and the outer surface. In some aspects, the core ring includes a slot and the discontinuity is in contact with the slot. In some aspects, the discontinuity is an opening in the core ring. 
     The invention further broadly comprises a blade for a turbine in a torque converter which includes first and second tabs disposed on an edge of the blade and arranged to affix the blade to a core ring for the torque converter. The edge is arranged to be proximate an outer surface of the core ring when the blade is affixed to the core ring. A notch in the edge is arranged to prevent capillary flow of joining material in a channel formed between the blade and the outer surface. 
     The invention further broadly comprises a torque converter which includes a core ring and a turbine blade connected to the core ring where the blade has an edge proximate an outer surface of the core ring. At least one channel is formed between the blade and the outer surface and joining material at least partially filling the channel and filling less than the entirety of the channel. 
     The invention also broadly comprises a method for controlling resonance of a turbine in a torque converter which includes the steps of: disposing a segment of a perimeter for the blade proximate an outer surface of a core ring for the torque converter; creating a channel between the segment and the outer surface; creating a discontinuity in the channel to block capillary action in the channel; and disposing a flowable connecting material in the channel. The method further fixedly connects less than the entirety of the segment to the outer surface. In some aspects, the method connects the turbine blade to the core ring. 
     It is a general object of the present invention to provide a torque converter with a turbine blade with reduced resonance and stiffness. 
     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 
         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 rear view of a present invention torque converter turbine having a plurality of present invention blades; 
         FIG. 9  is a rear view of the torque converter turbine shown in  FIG. 8  with the core ring removed; 
         FIG. 10  is a cross-sectional view of the torque converter turbine shown in  FIG. 9  along line  10 - 10  in  FIG. 9 ; 
         FIG. 11  is a perspective view of a present invention torque converter turbine blade; 
         FIG. 12  is a front view of a present invention core ring; 
         FIG. 13  is a cross-sectional view of the core ring shown in  FIG. 12 , taken generally at line  13 - 13  in  FIG. 12 ; 
         FIG. 14  is a perspective view of a turbine blade for use with a present invention core ring; and, 
         FIG. 15  is a rear view of a present invention core ring. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     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 rear view of present invention torque converter turbine  100  having a plurality of present invention blades  106 . 
       FIG. 9  is a rear view of torque converter turbine  100  shown in  FIG. 8  with the core ring removed. 
       FIG. 10  is a cross-sectional view of torque converter turbine  100  shown in  FIG. 9 , taken generally along line  10 - 10  in  FIG. 9 . 
       FIG. 11  is a perspective view of torque converter turbine blade  106 . The following should be viewed in light of  FIGS. 8 through 11 . Turbine  100  includes a plurality of blades  106 . Blades  106  are typically attached to turbine shell  102  and core ring  104  to form turbine  100 . Blades  106  are initially attached to the core ring using tabs, such as tabs  108  and  118 . Segment, or edge,  120  is the portion of perimeter  103  of the blade that faces outer surface of core ring  104 . That is, segment  120  is proximate the outer surface after the blade has been installed using the tabs. A gap, or channel, remains between the interface of edge  120  and outer surface of core ring  104 . As noted supra, flowable joining material is used to fixedly secure turbine blades to a core ring and capillary action is used to disperse the joining material throughout the interface. That is, the flowable material is disposed in the channel. The joining material can be any material known in the art for joining metal surfaces which can include, but is not limited to, brazing material, welding material, or a similar metallic attachment substance. In some aspects, a brazing paste is used to attach blades  106  to core ring  104 . Brazing paste flows along the interface of edge  120  surface and outer surface of core ring  104  when heat is applied, for example, in a brazing oven. The use of brazing paste enables the application of joining material in areas normally inaccessible once the blades are connected with tabs to the core ring. 
     Blades  106  include notches  130  disposed along perimeter  103  of the blades. Specifically, the notches are disposed along segment  120  of the perimeter. Notch  130  creates a discontinuity along the interface between segment  120  and the outer surface of the core ring. The discontinuity disrupts capillary action along the interface, interrupting the flow of the joining material. Alternately stated, the notch creates a section or segment  120  that is separated from the outer surface of core ring  104  a sufficient amount to prevent the flow of joining material along the channel formed between edge  120  and core ring  104 . Thus, the joining material does not join blade  106  to the outer ring at notch  130 . That is, the joining material fixedly connects less than the entirety of segment  120  and core ring  104 . 
     It should be understood that notch  130  is not limited to the size, shape, orientation, or position on segment  120  shown in the figures and that other sizes, shapes, orientations, or positions of segment  120  are within the spirit and scope of the claimed invention. It also should be understood that more than one notch  130  can be disposed on segment  120 . Further, it should be understood that a turbine can include blades  106  having different notches  130 . That is, not every blade has the same type of notch  130  or number of notches  130 . 
     Thus, turbine  100  includes one or more blades  106  unconnected to core ring  104  at points dispersed about the core ring. In some aspects, notch  130  will change the natural frequency of a turbine due to this variation in the application of the joining material. In some aspects, turbine  100  is more flexible, which will lead to reduced noise produced by the turbine. 
     Tabs  108  and  118 , integral to blades  106 , provide one means for attaching blades  106  to core ring  104 . Tabs  108 , which are disposed on edge  120  of blades  106 , are positioned in turbine  100  proximate inlet side  110  and are inserted through slots  114 , which are also proximate inlet side  110  of core ring  104 . Tabs  108  are bent after insertion through slots  114 , and serve to hold blades  106  to the front or outer surface of core ring  104 . In some aspects, tabs  118  on blades  106  are positioned proximate outlet side  112  of turbine  100 . Tabs  118  can further secure blades  106  to core ring  104  and are bent after insertion through slots  116 . In some aspects, notch  130  in blade  106  is positioned between tabs  108  and  118 . 
       FIG. 10  provides further detail regarding the configuration of turbine  100 . 
     In  FIG. 11 , tabs  108  and  118  are shown unbent which is the position of the tabs prior to the assembly of turbine  100 . After tabs  108  and  118  are inserted through slots  114  and  116 , respectively, the tabs are bent to secure blades  106  to core ring  104 . 
       FIG. 12  is a front view of present invention core ring  158 . 
       FIG. 13  is a cross section view of core ring  158 , taken generally at line  13 - 13  in  FIG. 12 . 
       FIG. 14  is a perspective view of turbine blade  151  for use with a present invention core ring. The following should be viewed in light of  FIGS. 12 through 14 . Blade  151  is used as an example in the following discussion, however, it should be understood that other turbine blades, such as blades  106  shown in  FIG. 11 , are usable with a present invention core ring. Ring  158  includes slots  161  and  163  used to receive tabs  153  and  155 , respectively. Slots  161  and  163  include widened portions  132  and  134 , respectively. The widened portions provide an open path between outer surface  165  of core ring  158  and inner surface  139  of core ring  158  after tabs  153  and  155  have been inserted through slots  161  and  163 , respectively and bent against surface  139 . By open path, we mean that a void or opening exists that links surfaces  165  and  139  and includes a break or opening in surface  165 . Once blade  151  is installed on the core ring, the edge facing surface  165 , that is edge  157 , is aligned with one or both of portions  132  and  134 . The alignment is orthogonal to surface  165 . That is, edge  157  passes over one or both of the portions. 
     Portions  132  and  134  form a discontinuity in the interface between edge  157  and surface  165 . The discontinuity disrupts capillary action along the interface, interrupting the flow of the joining material. Alternately stated, the widened portions create respective sections of edge  157  that are separated from surface  165  a sufficient amount to prevent the flow of joining material along the channel formed between edge  157  and surface  165 . Thus, the joining material does not join blade  151  to the outer ring at the widened portions. In some aspects, portions  132  are adjacent the end of slot  161  distal to outer circumference  167  of core ring  158 . In some aspects, portions  134  are positioned adjacent the end of slot  163  distal to inner circumference  169  of core ring  158 . 
     Although slots  161  and  163  in  FIG. 12  are each shown with respective widened portions, it should be understood that other configurations and combinations of portions  132  and  134  are within the spirit and scope of the invention as claimed. For example, widened portions  132  or  134  can be positioned on core ring  158  in tandem as depicted in  FIG. 12 , or alternatively (not shown), core ring  158  can comprise only portions  132 , only portions  134 , a combination of portions  132  and  134 , or combinations of slots with and without portions  132  or  134 . It also should be understood that portions  132  and  134  are not limited to the size and shape shown in the figures. The underlying principle is that the portions are sufficiently sized and positioned, with respect to the particular turbine blades installed on the core ring, to form a discontinuity with respect to the capillary action for the particular joining material used. 
     The location at which the joining material is applied to the core ring also is a factor as to where edge  157  is bonded to surface  165 . For example, in  FIG. 12 , braze paste applied proximate circumferences  167  and  169  flows along the channel formed between edge  157  and surface  165  toward slots  161  and  163 , respectively, until the paste reaches portions  132  and  134 , respectively. Upon reaching portions  132  or  134 , braze paste flowing along the channel formed by edge  157  and surface  165  stops flowing due to the void on surface  165  resulting from the open paths associated with the widened portions. That is, one wall of the channel needed for capillary action to drive the flow of braze paste has been eliminated by the widened portions, and capillary action is interrupted. Thus, the joining material does not fixedly connect surface  165  to the portion of edge  157  that lies between portions  132  and  134 . This lack of fixed connection between blade  151  and core ring  158  produces a turbine that is less stiff than a turbine that has the entire edge  157  fixedly connected to the core ring outer surface. 
       FIG. 15  is a front view of present invention core ring  171 . The following should be viewed in light of  FIGS. 14 and 15 . Blade  151  is used as an example in the following discussion, however, it should be understood that other turbine blades are usable with a present invention core ring. Ring  171  includes slots  173  and  175  used to receive tabs  153  and  155 , respectively. Openings  177  are located between outer circumference  179  of core ring  171  and inner circumference  181  of the core ring. Openings  177  provide an open path between outer surface  183  of the core ring and the inner surface (not shown) of the core ring after blades  151  have been installed on ring  171  (tabs  153  and  155  have been inserted through slots  173  and  175 , respectively and bent against the inside surface). Once blade  151  is installed on the core ring, the edge facing surface  183 , that is edge  157 , is aligned with opening  177 . The alignment is orthogonal to surface  183 . That is, edge  157  passes over the opening. 
     Opening  177  forms a discontinuity in the interface between edge  157  and surface  183 . The discontinuity disrupts capillary action along the interface, interrupting the flow of the joining material. Alternately stated, the openings create respective sections of edge  157  that are separated from surface  183  a sufficient amount to prevent the flow of joining material along the channel formed between edge  157  and surface  183 . Thus, the joining material does not join blade  151  to the outer ring at the openings. As long as openings  177  are aligned with blade  151  to form capillary action discontinuities, the openings are not limited to any position on core ring  171 . For example, the openings can be midway between the slots or closer to one or the other of the slots. A same core ring  171  can have openings in different positions with respect to the relative slots. It also is possible (not shown) for ring  183  to have respective slots  173  and  175  without an intervening opening  177 . 
     Alternative means of obstructing the flow of joining material such as applying detents, ridges, pockets or another obstruction can be used between the surface of the core ring and the turbine blade mounting surface. 
     The following should be viewed in light of  FIGS. 8 through 15 . A turbine is not limited to using any particular combination of present invention core rings and blades. For example, a turbine can use core ring  158  or  171  with blades  106 . 
     Thus, it is seen that the objects of the invention are efficiently obtained, although changes and modifications to 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 a specific preferred embodiment, it is clear that variations can be made without departing from the scope or spirit of the invention as claimed.