LIGHT WEIGHT TORQUE CONVERTER

Cross Reference to Related Applications

[0001] The present invention claims benefit of U.S. Provisional Application Serial Number 60/829,834, entitled "LIGHT WEIGHT TORQUE CONVERTER" filed on October 17, 2006, which is incorporated herein.

Field of the Invention

[0002] One embodiment of the present invention is directed toa hydrokinetic couplings, for example, including torque converters having a plurality of aluminum alloy components for use in automatic transmission powertrains of the type which are typically installed in, such as, automobiles and trucks. Further, the invention also includes a method of manufacturing torque converters.

Background of the Invention

[0003] In vehicle applications, engine torque and speed are translated between a prime mover, such as an internal combustion engine, to one or more wheels through the transmission in accordance with the tractive power demand of the vehicle. Hydrokinetic devices, such as torque converters, are often employed between the internal combustion engine and its associated transmission for transferring kinetic energy therebetween.

[0004] Torque converters have traditionally been made from stamped-steel components. However, the use of steel components limits potential maximum output efficiency and reduced mass moment of inertia due to the weight of steel and the attachment structure of the steel components and incorporate coiled springs to dampen torsional vibrations.

Summary of the Invention

[0005] According to the invention, there is provided a torque converter, as defined in claims 1-43.

Brief Description of the Drawings

[0006] The following detailed description, given by way of example and not intended to limit the invention solely thereto, will best be appreciated in conjunction with the accompanying drawings, wherein like reference numerals denote like elements and parts, in which:

[0007] Figure 1 is a cross section of one embodiment of the torque converter having a torsional damper according to the present invention;

[0008] Figure Ia represents a perspective view of one embodiment of an assembled torque converter, in accordance with the present invention;

[0009] Figure Ib represents an exploded view of one embodiment of a torque converter, in accordance with the present invention;

[0010] Figure 2a represents a perspective view of exterior surface of one embodiment of a torque converter cover, in accordance with the present invention;

[0011] Figure 2b represents a perspective view of the interior surface of one embodiment of a torque converter cover, in accordance with the present invention;

[0012] Figure 3a represents a perspective view of one embodiment of a lockup clutch assembly for use in a torque converter, in accordance with the present invention;

[0013] Figure 3b represents an exploded view of the lockup clutch assembly;

[0014] Figures 3 c and 3d are illustrations of two embodiments of wave springs;

[0015] Figures 3e and 3f are illustrations of one embodiment of a wave spring contracting/deflection and expanding/springing back;

[0016] Figure 3g is front view of one embodiment of the lockup clutch plate;

[0017] Figure 4a depicts a perspective view of one embodiment of a turbine assembly, in accordance with the present invention;

[0018] Figure 4b depicts an exploded view of the turbine assembly depicted in Figure 4a;

[0019] Figure 4c depicts a section view of one embodiment of the attachment of the turbine hub to the turbine shell, in accordance with the present invention;

[0020] Figure 4d is a magnified view of Figure 4a turbine shell and unitary turbine vortex ring and blade array structure complimentary features;

[0021] Figure 5 depicts a elevated plan view of one embodiment of a stator, in accordance with the present invention;

[0022] Figure 6a depicts a perspective view of one embodiment of a pump assembly, in accordance with the present invention;

[0023] Figure 6b depicts a perspective view of a sectioned pump shell and a unitary pump vortex ring and blade array structure of one embodiment of a pump assembly, and further depicts the metallurgical braze joint connectivity of the unitary vortex ring and blade array structure to the pump shell, in accordance with the present invention;

[0024] Figure 6c depicts an exploded view of the pump assembly depicted in Figure 6a;

[0025] Figure 6d is a magnified view of Figure 6b pump shell 37 and unitary pump vortex ring and blade array structure 38 complimentary features; and

[0026] Figure 7 depicts a perspective view of a flexplate.

Detailed Description of Preferred Embodiments

[0027] Figures 1, 1a, and Ib depict one embodiment of a torque converter 10, in accordance with the present invention, including a cover assembly 15, lockup clutch assembly 20, turbine assembly 25, stator assembly 30, and pump assembly 35. The cover assembly 15 may include a cover 16 can be formed of a metal sheet material, a pilot hub 17, and a plurality of engagement members 18 for attachment to a motor system (not shown), such as through a flexplate 60. The lockup clutch assembly 20 may include a lockup clutch plate 21, a friction

ring 22, a sealing member 23, and a gear ring 24. The turbine assembly 25 may include a turbine hub 26, a turbine shell 27, and a unitary turbine vortex ring and blade array structure 28. The stator assembly 30 may include a stator blade array 31, and a one-way clutch assembly 32 (Sprague). The pump assembly 35 may include a pump hub 36, a pump shell 37, and a unitary pump vortex ring and blade array structure 38. Figure 2a depicts the exterior face of the cover assembly 15 including a cover 16, can be formed of a metal sheet material composed of an aluminum alloy; a centrally positioned pilot hub 17, can be composed of a steel material; and a plurality of engagement members 18, can be composed of a steel material. The cover 16 can be made from 6061 T4 plate by stamping and can be heat treated to high strength T6 temper. It can be machined to the final dimensions. Cover 37 comprising a connector 36 adapted for fluid communication with a hydraulic system and is connected with the cover 16 to form an inner cavity 10a, wherein the inner cavity 10a is sized to house the lockup clutch plate 21, the monolithic blade structure 28, the monolithic pump structure 38, and the stator 31 therein. The lockup clutch plate 21, the monolithic blade structure 28, the monolithic pump structure 38, and the stator 31 are operably connect and capable of fluid communication therebetween.

[0028] For this application, monolithic is defined to describe a component that is made or formed into or from a single item and not from multiple parts and integral is defined as consisting or composed of parts that together constitute a component.

[0029] In one embodiment, the cover 16 is composed of an Aluminum Association 6xxx series aluminum alloy, in which the main alloying constituents include Si, Cu, Mg, and Cr, and can be Aluminum Association 6061 aluminum alloy, such as 0.40-0.8 wt. % Si, less than 0.7 wt. % Fe, 0.15-0.40 wt. % Cu, less than 0.15 wt. % Mn, 0.8-1.2 wt. % Mg, 0.04- 0.35 wt. % Cr, less than 0.25 wt % Zn, less than 0.15 wt. % Ti and a balance of Al with incidental impurities individually being less than 0.05 wt. % and totaling less than 0.15 wt %. Cover 16 can be formed using a stamping operation and has a geometry providing an friction engaging surface 19 on the interior face 16i of the cover 16 for frictional engagement to the friction ring 22 of the lockup clutch assembly 20, as depicted in Figure Ib.

[0030] Referring to Figure 2a, the pilot hub 17, can be composed of a steel material, is centrally positioned on the exterior face 16e of the cover 16 and joined to the aluminum alloy cover 16 by projection welding. The plurality of engagement members 18, similar to the pilot

hub 17 can be composed of a steel material and joined to the aluminum alloy cover 16 by projection welding. One embodiment of the engagement members 18 are configured to provide for mechanical fastening to the flex plate 60 (Fig. 1), such as by nut and bolt arrangement, wherein the nut member is provided by the engagement members 18.

[0031] Projection welding is a form of resistance welding, which produces coalescence of metals with the heat obtained from resistance to electrical current through the work parts held together under pressure by electrodes. The resulting welds are localized at predeteπnined points by projections, embossments, or intersections. Localization of heating is obtained by a projection or embossment on one or both of the parts being welded. By localizing heating through projection welding minimizes, eliminating the formation of a heat effected zone between at the interface of the aluminum alloy cover 16 and the steel pilot hub 17 and/or the plurality of engagement members 18.

[0032] A heat effected zone typically results from being subjected to high temperatures resulting in the formation of mechanical property reducing intermetallics at the junction of the two materials being joined, which typically results in a substantial reduction in the mechanical properties of the structures being metallurgically joined. For example, the heat effected zone typically has decreased tensile strength, elongation, and hardness when compared to the base metal of the structures being joined, which are not subjected to the heat effect. Therefore, in joining methods that subject the materials to be joined to high temperatures that result in melting, intermixing and alloying of the two materials being joined extending from the interface of the joint, such as arc welding, there is a measurable decrease in performance of the materials following joining, hi the present invention, the mechanical properties of the aluminum alloy cover and the steel pilot and engaging member following joining is substantially equal to the mechanical properties of the components prior to joining due to the localized heating resulting from projection welding that minimizes the formation of the heat effected zone.

[0033] Figures 3a and 3b depict one embodiment of a lockup clutch assembly 20, in accordance with the present invention. For example, the lockup clutch plate 21 is formed using a stamping operation and can be composed of an Aluminum Association 6xxx series aluminum alloy, in which the main alloying constituents include Si, Cu, Mg, and Cr, and representative of Aluminum Association 6013 aluminum alloy, including 0.40-0.8 wt. % Si,

less than 0.7 wt. % Fe, 0.15-0.40 wt. % Cu, less than 0.15 wt. % Mn, 0.8-1.2 wt. % Mg, 0.04-0.35 wt. % Cr, less than 0.25 wt % Zn, less than 0.15 wt. % Ti, and a balance of Al with incidental impurities individually being less than 0.05 wt. % and totaling less than 0.15 wt %.

[0034] The clutch assembly 20 of the present invention utilizes the higher flexibility (i.e., lower elastic modulus) of aluminum along with the damping ability of a polymer seal 23 to provide torsional flexibility in providing a smooth engagement of the clutch during operation of the torque converter and for reducing the vibration for engine torque pulses without the use of a separate spring mechanism such as coil springs. It should be understood that the lockup clutch plate input torsional load is transmitted from friction ring 22 into lockup clutch plate 21 through rim portion 21d and substantially follows a torsional load path from rim portion 21d to outer extensions 21b to generally trapezoidal or wedge section 21a to arms 50 to inner extensions 21c to hub portion 21 e to ring gear 26 to the mating components of torque converter 10 and ultimately into the hydraulic system of the transmission (Fig. 3g). The torsional loads and stresses are diminished in magnitude as it progresses along the lockup clutch plate torsional load path described above.

[0035] An exemplary embodiment of the lockup clutch plate 21 includes a plurality of integrally formed or monolithic arms 50. For the purposes of this disclosure, the term "integrally formed" denotes that the arms 50 are formed from the same sheet or part as the lockup clutch plate 21 and not a separate part assembled to the lockup clutch plate 21. Any conventional manufacturing process to form the integral component is acceptable, for example, a stamping operation. Arms 50 are configured to dampen vibration upon engagement of the torque converter systems with interfacing/mating dynamic systems and are illustrated and referred to hereinbelow as wave springs 50. Two examples of wave springs 50 are illustrated in Figures 3c and 3d. Generally, wave springs 50 can be defined by post- formed or post-stamped deformation of surfaces 21 f and 21 g of lockup clutch plate 21, for example, by dimensional drops from surfaces 21f and 21g (such as X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ ), internal radius R _x , and external radius R _y . Other geometric representations of wave springs 50 are also acceptable.

[0036] The torque converter systems engage motor systems that have a forcing frequency that causes a disturbing or resonant frequency. The wave springs 50 result in the natural frequency of the clutch to be at a different natural frequency than the engine to

minimize or eliminate resonant or otherwise to avoid resonant frequency. The wave springs 50 can be tuned to set the lockup clutch plate natural frequency to a predetermined value, for example above the natural frequency of an engine, that varies from system-to-system but is determinable by conventional analytical and empirical methods. Wave springs 50 can be tuned by adjusting one or more of the physical features of wave spring 50 including, but not limited to, dimensional drops from lockup clutch plate surfaces 21f and 21 g (such as X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ ), internal radius R _x , external radius R _y, inner radius (Ri), outer radius (R ₂ ), width (W), gaps Gi and G ₂ . The plurality of wave springs 50 define a predetermined spring rate such that high and low frequency torsional forces generated between the engine and lockup clutch plate 21 are dampened through to contraction/deflection (Fig. 3e) and expansion/spring back (Fig. 3f) of wave springs 50.

[0037] hi operation, the adjacently arranged wave springs 50 are interconnected at their respective ends 50a, 50b by the substantially flat section 21a. The torsional load is transmitted from one wave spring to the direct adjacent wave spring through the substantially flat section 21a. As one wave spring contracts or deflects or otherwise compresses, the directly adjacent wave spring expansion or springs back to original position. This cooperative interaction between directly adjacent wave springs will dampen the oscillating frequency of the torsional load. In this way, coiled springs of the conventional torsional damper can be eliminated. It should also be noted that the damping mechanism (arms or wave springs 50) does not interconnect or interact directly with adjacent or mating components of torque converter 10, such as turbine assembly 25, stator assembly 30, or pump assembly 35.

[0038] Now turning to Fig. 3g, one embodiment of the lockup clutch 21 includes a stamped aluminum part made from, for example, high strength 6013 aluminum alloy and takes advantage of the lower elastic modulus of aluminum compared to steel to obtain more springiness or resilience to operating torsional stresses and pulsations. Lockup clutch plate 21 can be stamped in the T4 temper and can be heat treated to T6 for maximum strength and durability. Lockup clutch plate 21 is illustrated having an integral series of eight tangential aπns or wave springs 50, equally spaced around the centeiiine (CL) and located approximately at inner radius (Ri) and outer radius (R ₂ ), wherein the radii difference (R ₂ -Ri) defines the approximate width (W) of wave spring 50. Wave springs 50 can be separated by a substantially flat and generally trapezoidal or wedge section 21a having a predetermined

average width (P). Wave springs 50 can be represented by a partial circular sector having angle φ and an area (A) approximately equal to 0.5(φ)(R ₂ -Ri) ² and arc length S approximately equal to (φ)(R _n ), where R _n is any radius including and between inner radius (Ri) and outer radius (R ₂ ). The width (W) of wave spring 50 may vary within the partial sector is adjustable be any conventional forming operation, such as trimming. Out of plane position of wave springs 50 results in at least a portion of wave spring 50 being oriented outward from or raised above and parallel with the substantially flat surface plane 2 If, 21g of lockup clutch plate 21 (Figures 3c and 3d) to form gaps Gi and G ₂₎ as shown four gaps for each gap Gi and G ₂ . Lockup clutch plate 21 can also include outer extensions 21b and inner extensions 21c to secure substantially flat section 21 to either rim portion 21 d or hub portion 2 Ie, respectively. One of ordinary skill in the art can size and shape the above features to tune-in the required torsional spring rate (k). It is within the contemplation of the invention that one or more of the above features can be eliminated depending on the desired dynamic response of the system. Arms 50 have been illustrated as a specifically shaped profile and a series of wave- like form normal to it to tune the performance of the clutch. However, any shaped profile and partial sector having φ, S, R ₁ , R ₂ , and W is acceptable.

[0039] Now returning to Figure 3b, clutch assembly 20 further includes polymer seal 23 configured to seal at least wave spring 50 portions of lockup clutch plate 21. The polymer material maybe molded over the lockup clutch plate 21 filling the spaces between the arms 50 as well as forming the lip seal to the center shaft. This rubber like polymer material bonded to the arms 50 provides additional damping and can be tuned to obtain the desired damping characteristics.

[0040] The friction ring 22 may be a high fπctional material, such as a ceramic material or other typically used brake material, and may be deposited on to the clutch assembly 20 or may be adhesively bound, providing the friction ring 22 is configured to engage the friction engaging surface 19 on the interior face 16i of the cover 16.

[0041] The gear ring 24 can be composed of hardened steel and configured for engagement to an exterior teeth 26e of the turbine hub 26 (Fig. 4b). hi one embodiment, gear ring 24 is centrally positioned to the lockup clutch plate 21 and is joined by friction welding. Friction welding involves the joining of metals without fusion or filler materials. The welds are created by the combined action of frictional heating and mechanical deformation. The

maximum temperature reached is of the order of 0.8 of the melting temperature. As opposed to conventional welding, that typically results in the formation of a heat effected zone within close proximity to the welded joint, at which the mechanical and corrosion properties of the base metals are substantially reduced, friction welding generates just enough heat to soften the aluminum so the two parts being joined can be forged together without melting of the metal and so substantially no mixing/ alloying of elements occurs. Thus, formation of brittle internietallic compounds in the joint area of iron and aluminum parts is avoided, thus ensuring stronger and more durable joints.

[0042] Figures 4a-4d depict one embodiment of a turbine assembly 25, in accordance with the present invention. Unitary or integral turbine vortex ring and blade array structure 28 includes a plurality of blades 28b and vortex ring 28a. The term unitary turbine vortex ring and blade array structure 28 denotes that the vortex ring 28a and blades 28b that form the blade array are a produced in a singular casting. Blade 28b can include an airfoil section 100 having a curved surface 100a that is complimentary to interior surface 27a of turbine shell 27, varying height 100b measured from root lOOd to curved surface 100a, and varying thickness 100c that varies along root lOOd and height 100b. One embodiment of blade thickness 100c increases from root lOOd to curved surface 100a. Unitary or integral turbine vortex ring and blade array structure 28 is adjacently positioned with relationship to turbine shell 27 and heated to the melting temperature of the braze material. Curved surface 100a can be positioned directly adjacent to interior surface 27a of turbine shell 27 such that the liquidous braze material will flow and fill the gap between curved surface 100a and interior surface 27a to form a fluid-tight seal to eliminate leakage between Unitary or integral turbine vortex ring and blade array structure 28 and shell 27, which causes turbulence. Further, the braze joint provides additional surface area to form a path to carry or transfer torsional load or stress.

[0043] hi one embodiment, the unitary turbine vortex ring structure and blade array 28 further includes at least one joining ring 51, wherein the at least one joining ring 51 includes a surface 51a complimentary with at least one annular groove 52 formed in the turbine shell 27 to provide a site for at least one of the braze joint metallurgical bond between the unitary turbine vortex ring and blade array structure 28 and the sheet turbine shell 27. Unitary turbine vortex ring and blade array structure 28 can be cast from an aluminum alloy, for example, an Aluminum Association 3xx series aluminum alloy, such as Aluminum Association A356 and

the alloy discussed in U.S. Patent No. 6,783,730. U.S. Patent No. 6,783,730, titled Al-Ni- Mn casting alloy for automotive and aerospace structural components, discloses another highly aluminum casting alloy for the unitary turbine vortex ring and blade array structure 28 and includes about 2-6 wt % Ni, about 1-3 wt. % Mn, less than about 1 wt. % Fe, and less than about 1 wt. % Si, with incidental elements and impurities, the disclosure of U.S. Patent No. 6,783,730 being incorporated in its entirety by reference. The braze joint provides additional surface area to form a path to carry or transfer torsional load or stress.

[0044] hi another embodiment, the turbine shell 27 is formed in a spinning operation from an aluminum alloy sheet material, for example a brazing sheet material. In one embodiment of the turbine shell 37 further comprises a series of annular grooves 52 located circumferential at predetermined radii (Ri) from the center line along the interior surface 27a (Fig. 4b), wherein the at least one joining ring 51- of the unitary turbine vortex ring 28 compliments the at least one annular groove 52 to provide a site for at least one of the braze joint metallurgical bond between the unitary turbine vortex ring and blade array structure 28 and the sheet turbine shell 27.

[0045] Pn another embodiment, the brazing sheet material of the turbine shell 27 can include a layered sheet composed of a prefluxed or non-prefluxed layer of Aluminum Association 4xxx series alloy, in which the prefluxed face of the brazing sheet is positioned to provide the surface for brazing engagement of the unitary turbine vortex ring and blade array structure 28. hi another embodiment, the face of the brazing sheet from which the turbine shell 27 is formed is positioned to provide the surface for brazed engagement by braze joint metallurgical bond to the unitary turbine vortex ring and blade array structure 28. This brazing operation is blind brazing of complex geometry without the intervention of an operator or technician to adjust the mating components for the desired match up or alignment of adjacent braze surfaces to produce the desire brazed joint.

[0046] The brazing sheet of the turbine shell 27 can be composed of at least one layer of Aluminum Association 4047 aluminum having a thickness that, for example, ranges from 0.1 to 0.3 mm thick, which can include 11.0-13.0 wt. % Si, less than 0.8 wt. % Fe, less than 0.30 wt. % Cu, less than 0.15 wt. % Mn, less than 0.1 wt. % Mg, less than 0.2 wt. % Zn, and a balance of Al with incidental impurities individually being less than 0.05 wt. % and totaling less than 0.15 wt %. Brazing sheet can further includes an aluminum layer composed of 0.6-

0.84 wt. % Si, 0.4-0.6 wt. % Fe, 0.4-0.64 wt. % Cu, 1.1 to 1.4 wt. % Mn, 0.2 -0.3 wt. % Mg, less than 0.05 wt % Zn, 0.10-0.20 wt. % Ti, and a balance of aluminum.

[0047] Now turning to Figure 4c, turbine hub 26 can be formed of a steel material and heat treated to provide a high strength hardened material. In one embodiment, the turbine hub 26 includes a main body portion 26a having a bore 26b configured for engagement to the transmission system (not shown) and an exterior surface 26c providing the engagement to the ring gear 24 of the lockup clutch assembly 20, wherein an friction metallurgical bond is formed between the turbine hub 26 and the sheet turbine shell 27 and can be positioned at least between an annular ring 26d disposed around the bore 26b through the main body portion 26a of the turbine hub 26 and a surface of the turbine shell 27 (Figure 1).

[0048] Inertia friction welding is a variation of friction welding in which the energy required to make the weld is supplied primarily by the stored rotational kinetic energy of the welding machine. In inertia friction welding, one of the work pieces (for example the turbine hub 26) is connected to a flywheel and the other is restrained from rotating. The flywheel is accelerated to a predetermined rotational speed, storing the required energy. The drive motor is disengaged and the work pieces are forced together by the friction welding force. This causes the faying surfaces to rub together under pressure. The kinetic energy stored in the rotating flywheel is dissipated as heat through friction at the weld interface as the flywheel speed decreases. An increase in friction welding force (forge force) may be applied before rotation stops. The forge force is maintained for a predetermined time after rotation ceases. An inertia friction metallurgical bond results.

[0049] Figure 5 depicts one embodiment of a stator assembly 30 for use in the torque converter 10 of the present invention. In one embodiment, the stator assembly 30 includes a die cast and machined stator 31 including a plurality of blades, and a one direction directional Sprague clutch 32. In one embodiment, the stator 31 is die cast from an aluminum alloy and machined to it's final form.

[0050] Figures 6a-6d depict one embodiment of a pump assembly 35, in accordance with the present invention. In one embodiment, the unitary pump vortex ring and blade array structure 38 includes a plurality of blades 38b and vortex ring 38 a. The term unitary pump vortex ring and blade array structure 38 denotes that the vortex ring 38a and blades 38b that

form the blade array are a produced in a singular casting. In one embodiment, the unitary pump vortex ring structure and blade array structure 38 further includes at least one joining ring 53, wherein the at least one joining ring 53 corresponds with at least one annular groove 54 formed in the pump shell 37 to provide a site for at least one of the braze joint metallurgical bond between the unitary pump vortex ring and blade array structure 38 and the metal sheet pump shell 37. This brazing operation is blind brazing of complex geometry without the intervention of an operator or technician to adjust the mating components for the desired match up or alignment of adjacent braze surfaces to produce the desire brazed joint. The braze joint provides additional surface area to form a path to carry or transfer torsional load or stress.

[0051] In one embodiment, the unitary pump vortex ring and blade array structure 38 is cast from an aluminum alloy, for example being an Aluminum Association 3xx series aluminum alloy, such as Aluminum Association A356 or the alloy disclosed in U.S. Patent No. 6,783,730. U.S. Patent No. 6,783,730, titled Al-Ni-Mn casting alloy for automotive and aerospace structural components, discloses another aluminum casting alloy for the unitary pump vortex ring and blade array structure 38 and includes about 2-6 wt % Ni, about 1-3 wt. % Mn, less than about 1 wt. % Fe, and less than about 1 wt. % Si, with incidental elements and impurities, the disclosure of U.S. Patent No. 6,783,730 being incorporated in its entirety by reference.

[0052] hi one embodiment, the pump shell 37 is formed in a spin forming operation from an aluminum alloy sheet material that can be made from a brazing sheet material, hi one embodiment the formed pump shell 37 further comprises a series of annular grooves 53, wherein the at least one joining ring of the unitary pump vortex ring 38 corresponds with the at least one annular groove 54 to provide a site for at least one of the braze joint metallurgical bond between the unitary pump vortex ring and blade array structure 38 and the sheet pump shell 37.

[0053] hi one embodiment, the brazing sheet material of the pump shell 37 includes a layered sheet composed of prefluxed or non-prefluxed layer of Aluminum Association 4xxx series alloy, which can have a thickness that ranges from 0.1 to 0.3 mm thick, in which the prefluxed face of the brazing sheet is positioned to provide the surface for brazing engagement of the unitary pump vortex ring and blade array structure 38. hi one

embodiment, the face of the brazing sheet from which the pump shell 37 is formed is positioned to provide the surface for brazed engagement by braze joint metallurgical bond to the unitary pump vortex ring and blade array structure 38.

[0054] The brazing sheet of the pump shell 37 can be composed of at least one layer of Aluminum Association 4047 aluminum. One embodiment of the brazing sheet can further include an aluminum layer composed of 0.6-0.84 wt. % Si, 0.4-0.6 wt. % Fe, 0.4-0.64 wt. % Cu, 1.1 to 1.4 wt. % Mn, 0.2 -0.3 wt. % Mg, less than 0.05 wt % Zn, 0.10-0.20 wt. % Ti, and a balance of aluminum. The brazing step can be conducted using a controlled atmosphere brazing (CAB) operation.

[0055] A pump hub 36 can be centrally positioned and joined to the sheet pump shell 37 by an electromagnetic or inertia friction metallurgical bond. The pump hub 36 includes a centrally positioned hollow shaft 36a having a shoulder 36b positioned at the base 36d of the hollow shaft 36a. Shoulder 36b can have an annular ring 36c disposed about the centrally positioned hollow shaft 36a, wherein the inertia friction metallurgical bond between the pump hub 36 and the sheet pump shell 37 is positioned between at least a surface 36e of the annular ring 36c and a surface 37a of the sheet pump shell 37.

[0056] Figure 7 depicts one embodiment of a light weight flexplate 60 for use with the torque converter described above with respect to Figures 1-6. The light weight flex plate 60 is provided having aluminum components for weight savings and steel components where required to meet higher strength components. The light weight flex plate of the present invention includes a stamped aluminum plate 65 including a plurality of integral wave springs 61 ; and a steel ring gear 62 connected to the perimeter 60a of the stamped aluminum plate by a metallurgical bond having substantially no heat effected zone at the interface 66 of the stamped aluminum plate 65 and the steel ring gear 62.

[0057] The stamped aluminum plate 65 includes the same features as lockup clutch plate 21. One embodiment of plate 65 is formed in a stamping operation and can be composed of an Aluminum Association 6013 series aluminum alloy, in which the main alloying constituents include Si, Cu, Mg, and Cr, and for example Aluminum Association 6013 aluminum alloy. The stamped aluminum plate 65 can be stamped having holes 63 for engagement to the engagement members 18 of the torque converter 10 and also to the engine

crank (not shown) and at holes 67. The steel ring gear 62 is configured for engagement by the starter motor (not shown) of the engine system and is joined to the stamped aluminum plate by a weld formed by inertia friction welding.

[0058] The torque converter of the present invention, results in a weight that is about 45%-50% lighter than its steel counter part (for example, 15.2 lbs vs 29 lbs). It has a mass moment of rotational inertia that is about 45%-50% less than that of the steel counterpart (for example, 215 lb-in ⁴ vs 425 lb-in ⁴ ) and can be produced using much fewer (for example, 20 vs 107) parts and uses a much simpler and more robust (for example, 16 vs 29) manufacturing steps.

[0059] While the disclosure has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the embodiments. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.