Torque converter with integrated fluid baffles on the front cover

Abstract

Torque converter (10) comprising: a rear cover (14), the rear cover (14) including a radially extending rear portion (14a) and an axially extending rear portion (14b) extending axially from a radially outer end of the radially extending rear portion (14a); and a front cover (12), the front cover (12) including a radially extending front portion (12a) and an axially extending front portion (12b) extending axially from a radially outer end of the radially extending front portion (12a), the front cover (12) including a plurality of baffles (76) formed as part of the front cover (12) and bent radially inward from the axially extending front portion (12b), wherein the axially extending front portion (12b) includes a plurality of circumferentially spaced notches (94), each of the baffles (76) extending radially from one of the notches (94), wherein each of the baffles (76) has two circumferentially facing and radially extending flat surfaces (76a, 76b) and two axially facing and radially extending edges (76c, 76b), wherein the circumferentially facing and radially extending flat surfaces (76a, 76b) are wider than the axially facing and radially extending edges (76c, 76d), wherein each of the baffles (76) further includes an axially extending and radially facing edge (76e) defined by radially inner ends of the circumferentially facing and radially extending planar surfaces (76a, 76b) and the axially extending and radially extending edges (76c, 76d), the axially extending and radially facing edge (76e) defining a radially innermost edge of the corresponding baffle (76), and wherein each baffle (76) has the same shape as the corresponding notch (94).

Description

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

[0002] US Pat. No. 8,327,636 B2 discloses a torque converter including a front cover with vanes that enhance fluid flow toward or away from a clutch pack. US Pat. No. 8,789,669 B2 discloses drive plates of a torque converter that include at least one protrusion to disrupt a Coriolis effect on the fluid in the torque converter. Further torque converters are disclosed in publications DE 100 82 530 B3 and JP 2003-2003 071 A. SUMMARY OF THE INVENTION

[0003] A torque converter is provided. The torque converter includes a rear cover and a front cover. The rear cover includes a radially extending rear portion and an axially extending rear portion extending axially from a radially outer end of the radially extending rear portion. The front cover includes a radially extending front portion and an axially extending front portion extending axially from a radially outer end of the radially extending front portion. The front cover includes a plurality of baffles formed as part of the front cover and bent radially inward from the axially extending front portion.

[0004] A method of forming a torque converter is also provided. The method includes cutting a plurality of tabs in an axially extending forward portion of a front cover; bending the tabs radially inward to form baffles; and attaching the axially extending forward portion to the axially extending rearward portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The following invention will be described below with reference to the following drawings, in which: Fig. 1 shows a side cross-sectional view of a torque converter having a front cover with baffles according to an embodiment of the present invention. Fig. 2 shows a perspective view of the front cover; and Fig. Figure 3 shows a perspective view of a tongue formed before being bent radially inward to form a baffle. DETAILED DESCRIPTION

[0006] The disclosure provides baffles on the front cover to reduce the response time after idle operation in a torque converter containing an axially displaceable turbine piston. The baffles are formed in the cover itself during stamping. The baffles are arranged to allow for a continuous weld seam and thus do not impede the use of the front cover as a containment vessel. By using, for example, a die to punch and form a baffle in the cover, the need for additional parts and assembly processes is eliminated.

[0007] 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 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" refer to an orientation parallel to the axis 81, the radius 82, and the circumference 83, respectively. The terms "axial," "radial," and "circumferential" also refer to an orientation parallel to the central axis 11. Corresponding terms axial, radial, and circumferential are used herein with reference to the central axis 11.

[0008] Fig. 2 shows a perspective view of the front cover 12. From the Fig. 1 and Fig. 2, the front cover 12 is substantially bowl-shaped and includes a radially extending portion 12a intersecting and extending radially from the central axis 11, and an axially extending annular portion 12b projecting axially from an outer periphery of the portion 12a. An edge portion 12c, beginning at an axially rearwardmost edge 12d of the portion 12b, is stepped radially inwardly to define a thinner portion 12e having an outer peripheral surface 12f that is radially inwardly offset from an outer peripheral surface 12g of a remaining portion, i.e., a thicker portion 12h of the portion 12b. The back cover 14 is similarly cup-shaped and includes a radially extending portion 14a forming the impeller shell 16 and an axially extending annular portion 14b projecting axially from an outer periphery of the radially extending portion 14a.An edge portion 14c, which begins at an axially rearwardmost edge 14d of portion 14b, is stepped radially outward to define a thinner portion 14e having an inner peripheral surface 14f that is radially offset from an inner peripheral surface 14g of a remaining portion, i.e., a thicker portion 14h of portion 14b. The covers 12, 14 are arranged relative to one another such that the portions 12e, 14e overlap one another, with the portion 12e lying within the portion 14e and the outer peripheral surface 12f abutting the inner peripheral surface 14f. A weld 17 is provided at the edge 14d and at the outer peripheral surface 12f of the thinner portion to join the front cover 12 and the rear cover 14 together.

[0009] The torque converter 10 from Fig. 1 also includes a turbine 20 configured to define a piston axially slidable toward and away from the impeller 18 to engage and disengage the impeller clutch of the impeller 18, thereby forming 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 turbine housing 22 includes a rounded blade support portion 28 shaped like an annular cup that engages the engine-side edges of the turbine blades 26.Radially outward of the blade support portion 28, a radially outer 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 radially extending, impeller-facing, planar annular surface 30a and an outermost periphery defining an outermost periphery of the turbine 20. Accordingly, the piston and the turbine housing 22 are formed from a single piece. Radially inward of the blade support portion 28, the turbine housing 22 includes a radially inner annular extension 31, which at a radially inner end thereof is adjacent to an axially extending inner peripheral portion 33, the inner peripheral surface of which abuts an outer peripheral surface of a hub 35.

[0010] The impeller 18 includes impeller blades 34, which are secured by tabs to the impeller shell 16 on a side thereof facing the gearbox and to an impeller center ring 37 on a side thereof facing the engine. The impeller shell 16 includes, on the radially extending portion 14a of the rear cover 14, a rounded blade support portion 32 shaped like an annular shell and abutting the edges of the impeller blades 34 facing the gearbox. Radially outward of the blade support portion 32, the radially extending portion 14a includes a radially extending wall 36 forming an impeller coupling and projecting radially outward from an outer periphery of the rounded blade support portion 32 to define an annular wall having a radially extending, turbine-facing, flat annular surface 36a.Accordingly, the impeller coupling and the impeller shell 16 are formed from a single piece. Radially inward of the blade support portion 32, the impeller shell 16 includes a radially inner annular 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.

[0011] A friction material 40 is bonded to the radially extending, impeller-facing surface 30a of the radially outer extension 30, engaging the radially extending wall 36. According to other embodiments, the friction material 40 may be bonded to the radially extending, turbine-facing surface 36a of the radially extending wall 36 instead of to the radially outer extension 30 or in addition. Regardless of whether the friction material 40 is bonded to the radially outer extension 30 or the radially extending wall 36, the friction material 40 is provided axially between the surfaces 30a, 36a.

[0012] The torque converter 10 also includes a stator 42 axially disposed between the turbine 20 and the impeller 18 to redirect fluid flowing from the turbine blades 26 before it reaches the impeller to increase the efficiency of the torque converter 10. The stator 42 includes a stator casting containing a plurality of blades 46 and a stator base 48. The stator 42 also includes a one-way clutch 50 supported by a centering disc 52 within the stator base. An axial thrust washer 54, axially disposed between the stator 42 and the impeller 18, is attached to the stator 42 at an outer periphery of the centering disc 52.

[0013] A damper assembly 62 is disposed between the front cover 12 and the turbine 20 and is designed to transmit torque from the turbine 20 to the input shaft of a transmission. The damper assembly 62 includes two cover plates—a turbine-facing cover plate 64 riveted to the turbine 20, and a front cover-facing cover plate 66. The cover plates 64, 66 axially support a set of arc springs 68 between them. The damper assembly 62 also includes two drive flanges 70, 71 axially disposed between the cover plates 64, 66. The drive flange 70 includes a radially inner hub 72 for rotationally connecting to the input shaft of a transmission. The two drive flanges 70, 71 contain circumferentially extending slots for receiving the springs 68. Radially outside the springs, the cover plates 64, 66 are connected to one another by a plurality of rivets 74 spaced apart from one another on the circumference.

[0014] According to one embodiment of the invention, the two Fig. 1 and Fig. 2, that the torque converter 10 is equipped with a plurality of circumferentially spaced baffles 76, which are connected to the front cover 12. The baffles 76 are rectangular in shape and each extend radially inward from the thinner portion 12e of the axially extending portion 12b of the front cover 12. The baffles 76 are formed integrally with the front cover 12. Each baffle is formed by piercing the axially extending portion 12b of the front cover 12 during the stamping of the front cover 12 to form a tongue ( Fig. 3) which is then bent radially inward to form the baffle plate 76.

[0015] According to Fig. 3, the piercing results in an axially extending slot 80 extending axially from the edge 12d into the axially extending portion 12b, and a circumferentially extending slot 82 extending circumferentially from a front end of the axially extending slot 80. The axially extending slot 80 is bounded on one side by an axially extending edge 84 of the thinner portion 12d, which extends radially from the outer peripheral surface 12f to an inner peripheral surface 12i of the thinner portion 12e, and on another side by an axially extending edge 86 of the tongue 78, which extends from the outer peripheral surface 78a of the tongue 78 to an inner peripheral surface 78b of the tongue 78.The circumferentially extending slot 82 is delimited on one side by a circumferentially extending edge 88 of the thinner portion 12e, which extends radially from the outer circumferential surface 12f to the inner circumferential surface 12i of the thinner portion 12e, and on another side by a circumferentially extending edge 90 of the tongue 78, which extends radially from the outer circumferential surface 78a of the tongue 78 to an inner circumferential surface 78b of the tongue 78.

[0016] After the slots 80, 82 have been cut according to the Fig. 2 and Fig. 3 to form the tongues have been cut into the axially extending portion 12b of the front cover 12, the tongues 78 are bent radially inward to form baffles 76 which extend radially from the axially extending portion 12b toward the central axis 11. The axially extending portion 12b merges into each baffle 76 at a corresponding bend 92, with the outer peripheral surface 12f merging at the bend 92 into a first circumferentially facing, flat, and radially extending surface 76a of the corresponding baffle 76 and an inner peripheral surface 12i merging at the bend 92 into a second circumferentially facing, flat, and radially extending surface 76b of the corresponding baffle 76.The edge 12d also merges into a first axially facing and radially extending edge 76c of each baffle 76, which jointly extend in the same plane, while the circumferentially extending edge 90 of each tongue 78 forms a second axially facing and radially extending edge 76d of the corresponding baffle 76 after the tongues 78 have been bent to form the baffles 76. In addition, each axially extending edge 86 of the tongue 78, after being bent, forms an axially extending and radially facing edge 76e defined by radially inner ends of the surfaces 76a, 76b and the edges 76c, 76, the edge 76e defining a radially innermost edge of the corresponding baffle 76. According to this embodiment, the surfaces 76a, 76b have one and the same width and are substantially wider than the edges 76c, 76d, 76e, which are of equal width to one another.

[0017] Bending the tabs 78 radially inward results in a plurality of circumferentially spaced notches 94 formed in the thinner portion 12e of the axially extending portion 12b. Each of the baffles 76 extends radially from a respective one of the notches 94, and each baffle 76 has the same shape as the corresponding notch. Each of the notches 94 is defined by the curve 92, a corresponding axially extending edge 84, and a corresponding axially extending edge 88. According to this embodiment, an end portion of each circumferentially extending slot 82 remains in the axially extending portion 12b, with the remaining portion of each slot 82 extending circumferentially from the corresponding notch 94.

[0018] After the tongues have been Fig.1 to 3 have been cut into the front cover 12 and bent radially inward to form the baffles 76, the thinner portion 12e of the axially extending portion 12b of the front cover 12 is pushed axially into the axially extending portion 12b of the rear cover 14 such that the thinner portion 12e overlaps the thinner portion 14e and the outer peripheral surface 12f abuts the inner peripheral surface 14f. The front cover 12 is arranged with respect to the rear cover 14 such that the axially extending portion 14b of the rear cover covers the notches 94 and the remaining portions of the circumferentially extending slots 82. Then, the rear cover 14 is welded to the front cover 12, forming a continuous weld 17 that connects the covers 12, 14 together and prevents any liquid from escaping from the covers 12, 14 through the notches 94 and the slots 82.

Claims

[1] Torque converter (10) comprising: a rear cover (14), the rear cover (14) including a radially extending rear portion (14a) and an axially extending rear portion (14b) extending axially from a radially outer end of the radially extending rear portion (14a); and a front cover (12), the front cover (12) including a radially extending front portion (12a) and an axially extending front portion (12b) extending axially from a radially outer end of the radially extending front portion (12a), the front cover (12) including a plurality of baffles (76) formed as part of the front cover (12) and bent radially inward from the axially extending front portion (12b), wherein the axially extending front portion (12b) includes a plurality of circumferentially spaced notches (94), each of the baffles (76) extending radially from one of the notches (94), wherein each of the baffles (76) has two circumferentially facing and radially extending flat surfaces (76a, 76b) and two axially facing and radially extending edges (76c, 76b), wherein the circumferentially facing and radially extending flat surfaces (76a, 76b) are wider than the axially facing and radially extending edges (76c, 76d), wherein each of the baffles (76) further includes an axially extending and radially facing edge (76e) defined by radially inner ends of the circumferentially facing and radially extending planar surfaces (76a, 76b) and the axially extending and radially extending edges (76c, 76d), the axially extending and radially facing edge (76e) defining a radially innermost edge of the corresponding baffle (76), and wherein each baffle (76) has the same shape as the corresponding notch (94). [2] The torque converter 10 of claim 1, wherein the axially extending rear portion (14b) overlies the notches (94). [3] The torque converter 10 of claim 2, further comprising a weld (17) for connecting the axially extending rear portion (14b) to the axially extending front portion (12b), the weld (17) being in contact with an edge of the axially extending rear portion (14b) and an outer peripheral surface of the axially extending front portion (12b). [4] The torque converter 10 of claim 1, wherein the axially extending rear portion (14b) includes a thinner rear portion (14e) and the axially extending front portion (12b) includes a thinner front portion (12e), the thinner front portion including the notches (94) and the thinner rear portion overlying the notches (94). [5] A method of forming a torque converter 10, the method comprising: Cutting out a plurality of tongues (78) in an axially extending front portion (12b) of a front cover (12); Bending the tongues (78) radially inward to form baffles (76); and connecting the radially extending front portion (12a) to an axially extending rear portion (14b) of a rear cover (14), wherein the bending defines a plurality of curves each connecting one of the baffles (76) to the axially extending front portion (12b), wherein the bending forms a plurality of circumferentially spaced-apart notches (94) in the axially extending front portion (12b), wherein cutting out each of the tongues (78) includes forming an axially extending slot (80) extending axially from an edge of the axially extending front portion (12b) and a circumferentially extending slot (82) extending circumferentially from the axially extending slot (80), each notch (94) being defined by one of the bends, one of the axially extending slots (80) and one of the circumferentially extending slots (82), and wherein each baffle (76) has the same shape as the corresponding notch (94). [6] The method of claim 5, further comprising axially inserting the axially extending front portion into the axially extending rear portion of the back cover 14 such that the axially extending rear portion overlies the notches (94).

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