Center ring with curved outer diameter for torque converter

Abstract

Center ring (28, 58) for an impeller (18) or a turbine (20) of a torque converter (10), the center ring (28, 58) comprising: an annular main part (86) which includes a convex surface portion (68) facing the blades (24, 56) and a concave surface portion (78) facing the stator (22); a bulged portion (60) on the outer diameter including an outwardly extending collar (62) projecting radially outward from the annular main portion (86), wherein the bulged portion (60) on the outer diameter includes an axially extending edge (80) on the outer diameter, wherein the edge (80) on the outer diameter runs parallel to a central axis of the central ring (28, 58) about which the central ring (28, 58) rotates during operation, and wherein the center ring (28, 58) further comprises slots (98) for receiving blade tabs extending from the convex surface portion (68) facing the blades (24, 56) to the concave surface portion (78) facing the stator (22).

Description

[0001] The present disclosure relates generally to torque converters and, more particularly, to center rings for torque converters. BACKGROUND OF THE INVENTION

[0002] Various designs of center rings for an impeller or a turbine of a torque converter can be found, for example, in the publications JP 2010 - 78 107 A, DE 11 2017 000 462 T5, JP 2010 - 78 106 A, DE 100 81 340 B4 or DE 199 37 258 A1.

[0003] Typically, a center ring 110 of a turbine or impeller of a torque converter, which is in Fig. 1 in a perspective cross-sectional view, a rounded outer diameter 112, which is part of a curved, blade-facing surface 114 of the center ring 110. At the outer diameter 112, the blade-facing surface 114 borders an outer diameter of a radially extending edge 116, which extends perpendicular to a central axis of the center ring 110. At an inner diameter thereof, the blade-facing surface 114 borders an edge 120 at the inner diameter, which extends axially and radially from the inner diameter of the blade-facing surface 112 and borders an inner diameter of a curved, stator-facing surface 122 of the center ring 110. The stator facing surface 122 extends radially and to a lesser extent axially outwardly from the curved stator facing surface 122 to an inner diameter of the radially extending edge 116.The center ring 110 has a constant thickness, and both the blade-facing surface 112 and the stator-facing surface 122 follow the same curved path as they extend radially outward and axially from the edge 120 to the edge 116. Slots 124 are formed in a space between the center ring 110, i.e., between the edges 116, 120, and through the center ring 110, for receiving connecting tabs of the turbine or impeller from the stator-facing surface 122 to the blade-facing surface 112.

[0004] It is also known to provide notches 126 in the radially extending edge 116 according to Fig. 2 extending from surface 114 to surface 122. Notches 126 are for manufacturing purposes only and do not affect the functionality of the center ring at all. The notches 126 on either side of the retaining tab ensure that the part rests against the bar and provide an expansion land to allow material to flow during the forming process. The part is notched only in the final station of the progressive die, by cutting out the retaining tabs on the outer diameter. Notches 126 can create weak points (areas of increased stress) when high pressures are applied. Fracture can occur at these locations. SUMMARY OF THE INVENTION

[0005] A center ring for a torque converter impeller or turbine is provided. The center ring includes an annular main portion having a convex blade-facing surface portion and a concave stator-facing surface portion, as well as a bulged portion at the outer diameter with an outwardly extending collar projecting radially outward from the annular main portion.

[0006] A torque converter is also provided. The torque converter includes a turbine; an impeller; and a stator for redirecting fluid flow from the turbine back to the impeller. The turbine and / or impeller includes the center ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will now be described with reference to the following drawings, in which: Fig. 1 shows a perspective cross-sectional view of a conventional center ring; Fig. Figure 2 shows a perspective view of another known center ring; Fig. 3 shows a side cross-sectional view of a torque converter according to an embodiment of the present invention; and Fig. 4 a perspective cross-sectional view of a center ring of the Fig. 3 shows the torque converter. DETAILED DESCRIPTION

[0008] A center ring is provided, containing a bulged outer diameter. A collar formed on the bulged outer diameter of the center ring further stiffens the part against the effects of high pressures. By providing the bulged outer diameter, a thinner or lower strength material can be used for the center ring while still providing sufficient strength for the part to withstand the forces required for the applications. Furthermore, the bulged outer diameter and outer collar are joined to the bar using an onion-ring cut, which allows the material to flow during forming. The part is then completely cut out, eliminating the need for notches on the outer diameter.The finished center ring is therefore stiffer and has no areas of increased stress on the outer diameter of the center ring caused by notches.

[0009] Fig. 3 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 connected 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 opposite the impeller 18 and a stator 22 axially between the impeller 18 and the turbine 20. The turbine 20 includes a plurality of blades 24 mounted to a rounded portion of a turbine housing 26 on a side of the turbine housing 26 facing the rear cover and to a center ring 28 according to an embodiment of the present invention.Furthermore, the turbine 20 includes a radially inner extension 30 that projects radially inward from the rounded portion 26. On a side of the turbine 20 facing the front cover, the turbine is connected to a damper assembly 32.

[0010] The damper assembly 32 includes a centrifugal pendulum absorber (CPA) 34 formed at a radially outer end of a first cover plate 36 riveted to a radially inner extension 30 of the turbine 20 by rivets 38. The damper assembly 32 further includes a second cover plate 40 axially between the first cover plate 36 and the front cover 12, with the cover plates 36, 40 axially supporting a set of a plurality of circumferentially spaced springs 42. Axially enclosed between the cover plates 36, 40, the damper assembly 32 includes a drive flange 44 whose radially inner end is configured as a hub 45 connected to a drive shaft of the transmission. The drive flange 44 includes a plurality of circumferentially extending slots formed therein for receiving the springs 42.Radially outward of the springs 42, the damper assembly 32 further includes a set of a plurality of circumferentially spaced, radially outer springs 46. A radially outer end of the second cover plate 40 forms a spring retainer 48 for receiving the springs 46.

[0011] A piston 50 is provided between the front cover 12 and the damper assembly 30, and a clutch disc 52 is provided axially between the piston 50 and the front cover 12. The clutch disc 52 includes, at a radially outer end thereof, a plurality of circumferentially spaced projections 54 that extend into the circumferential gaps formed between the springs 42. The clutch disc 50 is provided, at a radially inner end thereof, with a friction material on a side thereof facing the front cover that engages an axially inner surface of the front cover 12, and a friction material on a side thereof facing the rear cover that engages the piston 50. The piston 50, the clutch disc 52, and the axially inner surface of the front cover 12 form a lock-up clutch that non-rotatably connects the turbine 20 to the front cover 12 via the damper assembly 30.Fluid pressure differences between a side of the piston 50 facing the front cover and a side of the piston 50 facing the rear cover determine whether the piston 50 engages or separates from the front cover 12. The cover plates 36, 40 transmit torque from the turbine 20 to the drive flange 44, which in turn drives the transmission drive shaft. The cover plates 36, 40 jointly transmit the torque to the springs 46, which then transmit the torque to the clutch disc 52.

[0012] The impeller 18 also includes a plurality of blades 56 mounted on a rounded portion of the impeller shell 16 on a side of the impeller shell 16 facing the front cover and on a center ring 58 according to an embodiment of the present invention.

[0013] Fig. Figure 4 shows a perspective cross-sectional view of the center ring 28 or the center ring 58 according to an embodiment of the present invention. The center ring 28, 58 includes a bulged portion 60 on the outer diameter, which includes a radially outwardly extending, annular collar 62. The bulged portion 60 on the outer diameter is understood to mean that the outer edge does not follow the arcuate curvature of the rest of the center ring, but is bulged radially outward toward the radially extending edges 24a, 56a of the corresponding turbine or impeller blades 24, 56 ( Fig. 3). A blade-facing surface 64 of the center ring 28, 58 adjoins an inner edge 66 at an inner periphery thereof and extends radially outward from the inner edge 66. The blade-facing surface 64 has a convex portion 68 with an inner curved portion 70 adjacent to the inner edge 66 and extending axially from the stator 22 ( Fig. 3) and at the same time extends radially outwards from the inner edge 66. The inner curved section 70 then transitions at an apex 72, which is an annular surface of the central ring 28, 58 axially furthest away from the stator 22, into a central curved section 74 which is curved axially back towards the stator 22 and at the same time extends radially outwards, wherein the inner curved section 70 and the central curved section 74 define the convex section 68. At a transition section 76, which forms the outer edge of the central section 74, the surface 64 facing the blades transitions from the convex section 68 into an outer curved section 77 which forms a concave section 78, which in turn forms a surface of the curved section 60 at the outer edge which faces the blades.The concave section 78 is curved axially towards the stator 22 and adjoins an edge 80 on the outer edge, which extends in the axial direction and runs parallel to the central axis 11 (. Fig. 3).

[0014] A stator-facing surface 82 of the center ring 28, 58 adjoins an inner edge 66 at an inner edge thereof and extends radially outward from the inner edge 66. The stator-facing surface 82 has a concave portion 84 with an inner curved portion 86 adjacent to the inner edge 66, which is projecting from the stator 22 ( Fig.3) is curved axially away and at the same time extends radially outward from the inner edge 66. The inner curved section 86 then transitions at an axial apex 72, which is an annular surface of the center ring 28, 58 axially furthest from the stator 22, into a middle curved section 90, which is curved axially back towards the stator 22 and at the same time extends radially outward, wherein the inner curved section 86 and the middle curved section 90 define the concave section 84. At a transition section 92, which forms the outer edge of the middle section 90, the stator-facing surface 82 transitions from the concave section 84 into an outer curved section 93, which forms a convex section 94, which in turn forms a stator-facing surface of the curved section 60 on the outer diameter.The convex portion 94 curves back axially toward the stator 22 and is adjacent to the outer diameter edge 80. The inner diameter edge 66, the convex portion 68 of the blade-facing surface 64, and the concave portion 84 of the stator-facing surface 82 together define an annular main portion 86 of the center ring 28, 58, while the outer edge 80, the concave portion 78 of the blade-facing surface 64, and the convex portion 94 of the stator-facing surface 82 define an annular collar 62 extending radially outward from the annular main portion 96. The center ring 28, 58 can be stamped to form the annular main portion 96 and the annular collar 62 simultaneously.

[0015] Slots 98 for receiving blade tongues of the turbine or impeller blades are formed in a space of the main part 96, i.e. between the edge 66 and the transition sections 86, 92 and extend from the convex section 68 of the stator-facing surface 64 to the concave section 84 of the blade-facing surface 82.

Claims

[1] Center ring (28, 58) for an impeller (18) or a turbine (20) of a torque converter (10), the center ring (28, 58) comprising: an annular main part (86) which includes a convex surface section (68) facing the blades (24, 56) and a concave surface section (78) facing the stator (22); a bulged portion (60) on the outer diameter including an outwardly extending collar (62) projecting radially outward from the annular main portion (86), wherein the bulged portion (60) on the outer diameter includes an axially extending edge (80) on the outer diameter, wherein the edge (80) on the outer diameter runs parallel to a central axis of the central ring (28, 58) about which the central ring (28, 58) rotates during operation, and wherein the center ring (28, 58) further comprises slots (98) for receiving blade tongues extending from the convex surface portion (68) facing the blades (24, 56) to the concave surface portion (78) facing the stator (22). [2] The center ring (28, 58) of claim 1, wherein the bulged portion (60) includes, at the outer diameter, a concave surface portion (84) facing the blades (24, 56) radially outside the convex surface portion (68) facing the blades (24, 56). [3] The center ring (28, 58) of claim 1, wherein the bulged portion (60) includes on the outer diameter a convex surface portion (94) facing the stator (22) radially outside the concave surface portion (78) facing the stator (22). [4] Torque converter (10) comprising: a turbine; an impeller (18); and a stator (22) which redirects the fluid flow from the turbine (20) back to the impeller (18), wherein the turbine (20) and / or the impeller (18) includes the center ring (28, 58) according to claim 1.

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