Impeller of a torque converter, which contains projections for centering the stator

Abstract

Torque converter (10, 210, 310), which includes: a stator (70, 322) comprising a base body (76) and a plurality of blades (74, 330) on an outer circumferential surface (90) of the base body (76); and an impeller (18, 312) comprising an impeller housing (16, 220), wherein the impeller housing (16, 220) comprises at least one projection (120, 314) that abuts an axially extending surface (108) of the base body (76) of the stator (70, 322) to center the stator (70, 322) during assembly with respect to the impeller (18, 312), wherein the at least one projection (120, 314) is formed by a plurality of extruded rivets (214) or by a plurality of indentations (316).

Description

[0001] The present disclosure relates generally to torque converters and, more particularly, to centering stators in torque converters. BACKGROUND OF THE INVENTION

[0002] As is well known, when installing a torque converter into a transmission, a drive shaft, a stator shaft, and an impeller for the transmission are aligned with and then connected to a turbine hub, a stator hub, and an impeller hub for the torque converter, respectively. The stator is centered by axially extending rims formed on the inner diameters of the center rings of the turbine and impeller, which rest against the outer diameter of the stator rim during assembly.

[0003] Furthermore, patent application US 2015 / 369069 A1 discloses a specific turbine housing profile that adapts to a specific profile of the stator casting to radially center the stator. Patent application US 2015 / 0125290 A1 discloses an impeller center section that includes tabs for centering the stator.

[0004] From the publication DE 102 47 198 A1, another torque converter is known, comprising: a stator including a base body and a plurality of blades on an outer peripheral surface of the base body; and an impeller including an impeller shell, wherein the impeller shell has at least one projection abutting an axially extending surface of the base body of the stator to center the stator with respect to the impeller during assembly.

[0005] Further torque converters are disclosed in the documents DE 10 2008 035 775 A1 and US 2004 0 026 201 A1.

[0006] The object of the invention is to further improve the centering of the stator with respect to the impeller in a torque converter. SUMMARY OF THE INVENTION

[0007] A torque converter is provided. The torque converter includes a stator including a base body and a plurality of vanes on an outer peripheral surface of the base body, and an impeller including an impeller shell. The impeller shell includes at least one boss oriented to engage an axially extending surface of the stator base body to center the stator relative to the impeller during assembly.

[0008] A method for forming a torque converter is also provided. The method includes forming an impeller shell to include at least one protrusion on a surface of the impeller shell facing the stator; and centering the stator with respect to the impeller shell by bringing the at least one protrusion into contact with an axially extending surface of the base body. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will now be described with reference to the following drawings, in which: Fig. 1 shows a side cross-sectional view of a torque converter according to an embodiment of the present invention; Fig. 2 is an enlarged side cross-sectional view of a stator and part of an impeller of the Fig. 1 shown torque converter; Fig. 3 shows a side cross-sectional view of a torque converter according to another embodiment of the present invention; and Fig. 4 shows a side cross-sectional view of a torque converter according to another embodiment of the present invention. DETAILED DESCRIPTION

[0010] The disclosure provides a method for centering the stator of a torque converter during assembly by applying rivets or stampings to the impeller shell. According to some embodiments, the rivets on the impeller shell may also be used to center a thrust washer or thrust bearing.

[0011] Fig. 1 shows a side cross-sectional view of a torque converter 10 according to an embodiment of the present invention. The torque converter 10 is rotatable about a central axis 11 and includes a front cover 12 connectable to a crankshaft of an internal combustion engine, and a rear cover 14 forming a housing 16 of an impeller or pump 18. The terms axial, radial, and circumferential as used herein refer to the central axis 11. The torque converter 10 also includes a turbine 20 configured to be defined as a piston axially slidable toward and away from the impeller 18 to engage or disengage an impeller clutch of the impeller 18 to thereby form a lock-up clutch. The turbine 20 includes a turbine housing 22 and a center ring 24 supporting a plurality of turbine blades 26 therebetween.The blades 26 are secured to the turbine housing 22 by tabs on an engine-facing side thereof and to a center ring 24 by tabs on a transmission-facing side thereof. According to this embodiment, the center ring 24 does not include an axially extending rim formed on its inner diameters.

[0012] The turbine housing 22 includes a rounded blade support portion 28 shaped like an annular shell and abutting against the engine-facing edges of the turbine blades 26. Radially outward of the blade support portion 28, an outer radial extension 30, which forms the piston, projects radially outward from an outer periphery of the blade support portion 28 to define an annular projection having a flat, annular, radially extending surface 30a facing the impeller and an outermost periphery defining an outermost periphery of the turbine 20. Accordingly, the piston and the turbine housing 22 are formed integrally.Radially inside the blade support portion 28, the turbine housing 22 includes a radially inner annular extension 31 which, at a radially inner end thereof, merges into an inner, radially extending circumferential portion 33 whose inner circumferential surface abuts an outer circumferential surface of a hub 35.

[0013] The impeller 18 includes impeller blades 34, each of which is secured by tabs on a transmission-facing side thereof to the impeller shell 16 and on a motor-facing side thereof to a center ring 37 of the impeller. According to this embodiment, the center ring 37 does not include an axially extending rim formed on its inner diameters. The impeller shell 16 includes a rounded blade support portion 32 shaped like an annular cup that bears against the transmission-facing edges of the impeller blades 34. Radially outward of the blade support portion 32, a radially extending wall 36, forming an impeller coupling, projects radially outward from an outer periphery of the rounded blade support portion 32 and defines an annular wall having a flat, annular, radially extending surface 36a facing the turbine.Accordingly, the impeller coupling and the impeller shell 16 are formed integrally. Radially inward of the blade support portion 32, the impeller shell 16 includes an annular inner radial extension 39 extending radially inward from the blade support portion 32. A radially inner end of the extension 39 is connected to an impeller hub 41.

[0014] A friction material 40 is bonded to the impeller-facing, radially extending surface 30a of the outer radial extension 30, engaging the radially extending wall 36. According to other embodiments, the friction material 40 may be bonded not only to the outer radial extension 30, but instead or additionally to the turbine-facing, radially extending surface 36a of the radially extending wall 36. Regardless of whether the friction material 40 is bonded to the outer radial extension 30 or the radially extending wall 36, the friction material 40 is provided axially between the surfaces 30a, 36a.

[0015] A damper assembly 42 is provided between the front cover 12 and the turbine 20, which serves to transmit torque from the turbine 20 to the input shaft of a transmission. The damper assembly 42 includes two discs—a first, or turbine-facing, disc 44 riveted to the turbine 20 by rivets 46, and a second, or front cover-facing, disc 48 connected to a hub 50 whose internal tooth profile 52 is connected to the input shaft of the transmission.

[0016] At a radially outer end of the first disc 44, it includes a spring receptacle 54 for holding arc springs 56. The spring receptacle 54 includes circumferentially extending arcuate compartments 58, each receiving one of the arc springs 56, with each arcuate compartment having an inner surface that conforms to an outer surface of the corresponding arc spring 56. The radially outer end of the first disc 44 includes drive tabs 60 circumferentially between the compartments 58. Each drive tab 60 is configured to engage a circumferential edge of each of the arc springs 56 and is axially and radially offset with respect to the compartments 58.

[0017] The second disc 48 is provided with holes 64 extending axially therethrough to reduce axial stiffness of the disc 48 and to receive pins of an axial thrust washer 66 axially sandwiched between a radially extending inner surface of the front cover 12 and the second disc 48. At a radially outer end, the second disc 48 includes a plurality of circumferentially spaced-apart driven tabs 68 that extend axially into circumferential spaces between the springs 56 such that each driven tab 68 contacts a circumferential edge of each of the arc springs 56. Thus, each arc spring 56 is circumferentially supported between a drive tab 60 and a driven tab 68.During operation of the torque converter 10, the first disc 44 transmits torque from the turbine 20 to the second disc 48 via the drive tongues 60, which transmit the torque through the springs 56 to the driven tongues 68. The second disc 48, in turn, transmits the torque through the internal tooth profile 52 of the hub 50 to the input shaft of the transmission.

[0018] The torque converter 10 also includes a stator 70 axially disposed between the turbine 20 and the impeller 18 to redirect fluid flowing from the turbine blades 26 before the fluid reaches the impeller 18 to increase the efficiency of the torque converter 10. The stator 70 includes a stator casting 72 having a plurality of blades 74 and a stator base 76. The stator 70 also includes a one-way clutch 78 supported within the stator base 76 by a centering disc 80. An axial thrust washer 82 is attached to the stator 70 at an outer periphery of the centering disc 80 and is axially disposed between the stator 70 and the impeller 18. The one-way clutch 78 includes an inner race 84, an outer race 86, and rolling elements 88 radially between the inner race 84 and the outer race 86.The stator casting 72 is non-rotatably connected to the outer race 86, and depending on the operating conditions of the torque converter 10, the inner race 84 and the outer race 86 are non-rotatably connected to each other or rotatable with respect to each other.

[0019] Fig. 2 shows an enlarged side cross-sectional view of the stator 70 and a portion of the impeller 18. The vanes 74 are radially supported between an outer peripheral surface 90 of the stator base 76 and an inner peripheral surface of a skirt 92. The stator base 76 includes an annular recess 94 formed on the impeller-facing side 96 of the stator base and receiving the one-way clutch 78. The annular recess 94 is defined by two steps—a radially inner step 94a that receives the inner race 84 and a radially outer step 94b that receives the outer race 86. The radially outer step 94b includes a radially extending surface 98 and an axially extending peripheral surface 100 that extends from a radially outer edge to the radially extending surface 98.Radially outward of the annular recess 94, the stator casting 72 is provided with a cavity 102 that defines an annular groove 104 within the stator base body 76. More specifically, the cavity 102 is formed radially inward of the outer circumferential surface 90 of the stator base body 76 and radially outward of the axially extending circumferential surface 100 that defines the outermost circumferential surface of the annular recess 94. The groove 104 extends circumferentially about the central axis 11 (. Fig. 1), and an outer periphery of the groove 104 is defined by an axially extending circumferential surface 108 of an axially projecting ring 110. An outer circumferential surface of a first axially projecting ring 110 defines an outer circumferential surface 90 of the stator base 76, and the axially projecting ring 110 includes a radially extending surface 112 extending radially from the axially extending circumferential surface 108 to the outer circumferential surface 90. The cavity 102 is defined by the first axially projecting ring 110 and a second axially projecting ring 114 and further includes a radially extending surface 116 extending radially inward from the axially extending surface 108 and an axially extending inner circumferential surface 118 extending axially from an inner diameter of the radially extending surface 116.

[0020] According to one embodiment of the present invention, the impeller housing 16 is provided with at least one axially extending projection 120 to center the stator with respect to the impeller 18 during assembly of the torque converter 10. According to a preferred embodiment, the at least one axially extending projection 120 includes a plurality of projections 120 that are circumferentially spaced from one another around the central axis 11 ( Fig. 1). The projections 120, which are aligned radially inward of the stator blades 74 and radially outward of the one-way clutch 78, are formed on a radially extending surface 39a of the radially inner annular extension 39 facing the stator. The radially extending surface 39a is flat and extends perpendicular to the central axis 11 ( Fig. 1), and the projections 120 extend axially from the radially extending surface 39a to the stator 70. The projections 120 are formed radially inward of the axially extending surface 108 of the protruding ring 110, and an axial tip 122 of each projection 120 is disposed within the annular groove 104, with the axial tip 122 extending axially from the surface 39a beyond the radially extending surface 112 of the ring 110, such that the projections 120 serve to center the stator 70 with respect to the impeller 18 during assembly of the torque converter 10. More specifically, a radially outer, axially extending surface 124 of each projection 120 can abut the axially extending surface 108 of the stator 70 during assembly to properly center the stator 70.

[0021] According to this embodiment, the projections 120 are formed in the form of extruded rivets 126. The extruded rivets 126 are formed by extruding the impeller shell 16. More specifically, the annular inner radial extension 39 is extruded by means of a riveting tool by bringing it into contact with a gear-facing, radially extending surface 39b of the radially inner annular extension 39 such that a recess 128 is formed in the gear-facing, radially extending surface 39b and a projection 120 are formed. After the projections 120 are formed, the stator 70 is centered with respect to the impeller 18 by centering the axially extending surface 108 radially outward of the projections 120.

[0022] Fig. 3 shows a side cross-sectional view of a torque converter 210 according to another embodiment of the present invention. The torque converter 210 is formed in substantially the same manner as the torque converter 10, with one difference being that the impeller 212 is provided with bosses / rivets 214 that, in addition to centering the stator 70 relative to the impeller 212 during assembly of the torque converter 10, are used to center a thrust washer or thrust bearing 216 axially disposed between the impeller 212 and the stator 70. More specifically, the thrust washer or thrust bearing 216 is axially enclosed between the centering washer 80 of the stator 70 and an annular inner radial extension 218 of the impeller shell 220.

[0023] The rivets 214 include a radially inner, axially extending surface 222 of the rivet 214, which is machined to have a slight arcuate shape that conforms to an outer peripheral surface 224 of the thrust washer or thrust bearing 216, which is annular. The rivets 214 may guide the thrust washer or thrust bearing 216 or provide additional guidance to prevent the thrust washer or thrust bearing 216 from falling off when the torque converter buckles under loaded conditions. The stator 70 may be indirectly centered by the rivets 214 centering the thrust washer or thrust bearing 216, after which the thrust washer or thrust bearing 216 is attached to the centering washer 80, thus centering the stator 70.

[0024] Fig.4 shows a side cross-sectional view of a torque converter 310 according to another embodiment of the present invention. The impeller 312 of the torque converter 310 is formed in substantially the same manner as the impeller 18, with the exception that the impeller 312 is provided with at least one protrusion 314 in the form of at least one embossment 316, and the at least one protrusion 314 is formed at a location radially further outward than the at least one protrusion 120 on the annular inner radial extension 318. According to a preferred embodiment, the at least one axially extending protrusion 314 includes a plurality of protrusions 314 circumferentially spaced from one another about the central axis 320.The stator 322 is formed in substantially the same manner as the stator 70, with one difference being that an axially extending inner circumferential surface 324 of the protruding ring 326 of the stator 322 is machined to form a bevel on each of the indentations 316 that mates with a bevel of a radially outer, axially extending surface 328 of the indentations 316.

[0025] The projections 314 are aligned radially inward of the stator blades 330 and radially outward of the one-way clutch 332 and are formed on a curved, stator-facing, radially extending surface 318a of a radially inner annular extension 318, which radially inner extension is connected to the rounded blade support portion 32 of the impeller 312. The projections 314 extend axially toward the stator 70 from the radially extending surface 318a.The projections 314 are formed radially inward of the axially extending surface 324 of the protruding ring 326, and an axial tip 334 of each projection 314 is disposed within an annular groove 336, with the axial tip 334 extending axially from the surface 318 beyond the radially extending surface 338 of the ring 326, such that the projections 324 act to center the stator 322 with respect to the impeller 312 during assembly of the torque converter 310. More specifically, the radially outer, axially extending surface 328 of each projection 314 can abut the axially extending surface 324 of the stator 322 during assembly to properly center the stator 322.

[0026] The projections 314 are formed by a stamping tool that stamps the radially inner annular extension 318 by mating it with a transmission-facing, radially extending surface 318b of the radially inner annular extension 318 to form a recess in the transmission-facing, radially extending surface 318b and a projection 314. After the projections 314 are formed, the stator 322 is centered with respect to the impeller 312 by centering the axially extending surface 324 radially outward of the projections 314.

[0027] In the foregoing description, the invention has been described with reference to specific exemplary embodiments and examples thereof. However, it should be understood that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. Accordingly, the description and drawings are to be considered as illustrative rather than limiting.

Claims

[1] Torque converter (10, 210, 310) comprising: a stator (70, 322) including a base body (76) and a plurality of blades (74, 330) on an outer peripheral surface (90) of the base body (76); and an impeller (18, 312) containing an impeller housing (16, 220), the impeller housing (16, 220) including at least one projection (120, 314) abutting an axially extending surface (108) of the base body (76) of the stator (70, 322) to center the stator (70, 322) with respect to the impeller (18, 312) during assembly, wherein the at least one projection (120, 314) is formed by a plurality of extruded rivets (214) or by a plurality of indentations (316). [2] The torque converter (10, 210, 310) of claim 1, wherein the impeller shell (16, 220) includes a plurality of impeller blades (34), a rounded blade support portion (32) abutting the impeller blades (34), and a radially inner annular extension (39) extending radially inwardly from the rounded blade support portion (32), the radially inner annular extension (39) including the at least one projection (120, 314). [3] Torque converter (10, 210, 310) according to claim 1, wherein the base body (76) of the stator (70, 322) includes an annular groove (104) and the at least one projection (120, 314) extends axially into the annular groove (104). [4] The torque converter (10, 210, 310) of claim 1, wherein the base body (76) of the stator (70, 322) includes an axially projecting ring (110) containing the axially extending surface (108), and wherein the at least one projection (120, 314) is disposed radially inward of the axially projecting ring (110). [5] The torque converter (10, 210, 310) of claim 1, further comprising a thrust washer or thrust bearing (216), wherein the at least one projection (120, 314) includes a radially inner surface (222) abutting an outer peripheral surface of the thrust washer or thrust bearing (216) to center the thrust washer or thrust bearing (216) with respect to the impeller (18, 312). [6] A method of forming a torque converter (10, 210, 310), the method comprising: Forming an impeller housing (16, 220) including at least one projection (120, 314) on a surface of the impeller housing (16, 220) facing the stator (70, 322); Providing a stator (70, 322) including a base body (76) and a plurality of blades (74, 330) on an outer peripheral surface (90) of the base body (76); and Centering the stator (70, 322) with respect to the impeller housing (16, 220) by the at least one projection (120, 314) abutting an axially extending surface (108) of the base body (76), wherein forming the at least one projection (120, 314) includes extruding the impeller (18, 312) to form a plurality of extruded rivets (214) or embossing the impeller (18, 312) to form a plurality of embossments (316). [7] The method of claim 6, wherein the impeller shell (16, 220) includes a plurality of impeller blades (34), a rounded blade support portion (32) abutting the impeller blades (34), and an annular radially inner extension (39) extending radially inwardly from the rounded blade support portion (32), the at least one projection (120, 314) being formed on the radially inner annular extension (39).

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