Torque converter with a stator axial bearing

Abstract

Torque converter (10) which includes: a wheel (18) containing a wheel housing (16); a turbine (20) containing a turbine casing (352); and a stator (26) axially between the turbine (20) and the impeller (18), wherein a first fluid flow is generated between the impeller (18) and the stator (26) and a second fluid flow is generated between the turbine (20) and the stator (26); and an axial bearing (34) axially between the impeller (18) and the stator (26) or axially between the turbine (20) and the stator (26), wherein the axial bearing (34) includes a bearing surface (36) which serves to maintain a lubricating film on it in a region of the first fluid flow or the second fluid flow during operation of the torque converter (10). wherein the axial bearing (34) comprises a plurality of circumferential sections (41), each circumferential section (41) comprising a first section (42) with a groove (44) extending from an inner circumferential surface (46) of the axial bearing (34) to the outer circumferential surface (48) of the axial bearing (34), a second section (50) comprising a flat surface (52) of uniform thickness, and a third section (54) comprising an inclined surface (56) extending around the circumference between the groove (44) and the flat surface (52), wherein the thickness of the third section (54) gradually decreases along the inclined surface (56) around the circumference from the flat surface (52) to the groove (44). decreases, wherein the flat surface (52) is formed by an abrasion-resistant material (158) which is housed in a slot (160) of the second section (50) of the axial bearing (34).

Description

[0001] The present disclosure relates generally to torque converters and in particular to bearings between the stator and the impeller of torque converters. BACKGROUND OF THE INVENTION

[0002] US Patent 6,231,309 discloses a pressure plate for the reactor of a torque converter. Thrust bearings with inclined surfaces are known and are described on page 2140 of the 25th edition of the Machinery's Handbook. It is known to use thrust bearings with inclined surfaces in torque converters, especially between a stator and an impeller.

[0003] Publications DE 100 11 204 A1, DE 195 33 151 A1 and DE 10 2009 029 496 A1 show hydrodynamic torque converters, each with an axial sliding bearing and a radial lubrication groove for forming a lubricating film.

[0004] Utility model DE 203 17 497 U1 discloses an axial sliding bearing with a flat sliding surface and at least one bearing surface in the form of a profiled circular annular surface forming a lubrication gap between the sliding surface and the bearing surface, wherein the bearing surface has several radially extending and outwardly open lubricating oil grooves formed in it, several wedge surfaces and flat detent surfaces.

[0005] The Fig. .9 on page 81 and the Fig. Figure 28 on page 107 in "STEINHILPER, W.; SAUER, B.: Konstruktionselemente des Maschinenbaus 2 - Grundlagen von Maschinenelemente für Antriebsaufgaben. 6. Aufl. Berlin Heidelberg: Springer, 2008. S. 69, 70, 73, 74, 79 to 81 and 105 to 107. - ISBN 978-3-540-76653-7" shows a standard design of axial plain bearings.

[0006] The object of the present invention is to further improve an axial sliding bearing of a hydrodynamic torque converter. BRIEF SUMMARY OF THE INVENTION

[0007] A torque converter is provided. The torque converter includes an impeller with an impeller housing, a turbine with a turbine housing, and a stator axially located between the turbine and the impeller. A first fluid flow is generated between the impeller and the stator, and a second fluid flow is generated between the turbine and the stator. Furthermore, the torque converter includes a thrust bearing axially located either between the impeller and the stator or axially between the turbine and the stator. The thrust bearing has a bearing surface to maintain a lubricating film during operation of the torque converter in either the first or second fluid flow region.

[0008] A method for forming a torque converter is also provided. This method involves providing an axial bearing surface in the region of a first fluid flow axially between an impeller and a stator, or in the region of a second fluid flow axially between a turbine and the stator, such that a lubricating film is maintained on the axial bearing surface during operation of the torque converter in the region of the first fluid flow or in the region of the second fluid flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention is described below with reference to the following drawings, wherein: Fig. 1 shows a lateral cross-sectional view of a torque converter according to an embodiment of the present invention; the Fig. 2a and Fig. 2b shows lateral cross-sectional views illustrating the fluid flow through a torque converter, which corresponds to the one described in Fig. The torque converter shown in section 1 is similar; Fig. 3a shows a perspective view of an axial bearing for use between a stator and an impeller of the torque converter according to an embodiment of the present invention; Fig. 3b a cross-sectional view of the axial bearing along the section line AA in Fig. 3b shows; Fig. 4a shows a perspective view of an axial bearing for use between a stator and an impeller of the torque converter according to another embodiment of the present invention; Fig. 4b a cross-sectional view of the axial bearing along the section line BB in Fig. 4a shows; Fig. 5 shows a stator with an axial bearing formed on it in one piece; Fig. 6 shows a lateral cross-sectional view of a torque converter according to another embodiment of the present invention; DETAILED DESCRIPTION

[0010] The present disclosure provides a special ramped or inclined surface with an adjacent short flat surface, forming a bearing lubrication surface for a stator. According to one embodiment, the bearing surface is part of a separate component attached to the stator, and according to another embodiment, the surface is part of the stator casting. The inclined surface and the flat surface are designed to maintain a lubricating film of converter fluid on the bearing surface, thus preventing metal-to-metal contact between the bearing surface and an axial inner surface of the impeller housing. The lubricating film is generated by the relative movement between the stator and the pump, and the fluid film generates a pressure that counteracts the compressive force of the stator.Embodiments of the invention can be particularly advantageous for torque converters with axially displaceable turbines that engage and disengage with the impeller housing, since the pressure forces acting on the pump at the bearing surface can be significantly lower (by 50%) than in a conventional torque converter due to the absence of turbine thrust. The bearing surface can also be advantageous when used in conventional torque converters with low pressure forces. The counterforce generated by the fluid film can be precisely matched to the calculated pressure values. Embodiments of the present invention can also contribute to reducing the axial dimensions of the torque converter.

[0011] Fig. Figure 1 shows a side cross-sectional view of a torque converter 10 according to an embodiment of the present invention. The torque converter 10 comprises a front cover 12 for connection to a crankshaft of an internal combustion engine and a rear cover 14, which forms a housing 16 for an impeller or a pump 18. The torque converter 10 also comprises a turbine 20 with a radially outer extension 22, which projects radially outward from the outer circumference of a blade support section of the turbine 20. The turbine 20 is axially displaceable toward and away from the impeller 18 in order to engage and disengage with the impeller 18. A friction material 24 is applied to a surface of the radially outer extension 22 for engaging the rear cover 14. The turbine 20 is connected to a damper assembly 40, which is driven circumferentially by the turbine 20 and is arranged between the turbine 20 and the front cover 12.The torque converter 10 also includes a stator 26 between the turbine 20 and the impeller 18, as well as a freewheel clutch 28 that supports the stator 26. The freewheel clutch 28 is held in place within the stator 26 by a centering disk 30. The stator 26 includes a base 32 and an axial bearing 34 adjacent to the base 32, with an axial bearing surface 36 facing the impeller housing 16. More precisely, the axial bearing surface 36 faces axially an axial surface of a radially extending section 37 of the impeller housing 16, located between a rounded section 39 for holding the blades 81 of the impeller 18 and a hub 84 of the impeller 18. According to this embodiment, the bearing 34 is an axial bearing with inclined surfaces. The bearing surface 36 is shaped in such a way as to maintain a lubricating film that prevents contact between the bearing surface 36 and the impeller housing 16.The lubricating film generates a sufficiently high pressure between the impeller housing 16 and the stator 26 such that, during operation, the force generated by the pressure of the lubricating film exceeds the thrust force of the stator 26 in the direction of the impeller 18.

[0012] The axial bearing 34 can be attached to a radially inner end of the socket 32 ​​by a snap-fit ​​connection and may have a rotation-preventing feature that may be manufactured as a single piece with the snap-fit ​​connection or arranged separately. The rotation-preventing feature may be a pin or a lug on the axial bearing 34 that can bear a larger load and engages in a hole in an adjacent surface or plane of the socket 32.

[0013] According to another embodiment, the axial bearing 34 can be connected to the impeller housing 16, and the axial bearing surface 36 can be axially oriented towards an axial surface of the base 32 that points towards the impeller 18, so that a lubricating film is maintained on the axial bearing surface 36, which prevents contact between the bearing surface 36 and the stator 26 and, in particular, the base 32. According to such an embodiment, the axial bearing 34 can be attached to the impeller housing 16 by a snap-fit ​​connection and can have a rotation-resistant feature that can be manufactured in one piece with the snap-fit ​​connection or arranged separately.

[0014] The Fig. 2a and Fig. Figure 2b shows lateral cross-sectional views illustrating the fluid flow through a torque converter 110, which corresponds to the one described in Figure 2. Fig. The torque converter shown in section 1 is similar. Torque converters 10 and 110 contain different damper assemblies 40 and 80 respectively and other shape variants; however, the one shown in section 1 applies. Fig. 2a, Fig. The fluid flow described in 2b also applies to Fig. 1. Fig. Figure 2a shows the fluid flow through the torque converter 10 when the lock-up clutch is engaged by the friction material 24 on the radially outer extension 22 of the turbine 20, which is pressed against a radially extending section of the impeller housing 16. Fig. Figure 2a shows that the fluid presses the turbine 20 against the impeller 18 and flows radially inwards through radially extending cavities formed in the friction material 24. When the clutch is engaged, the fluid flows inwards through the drive shaft 82 of a gearbox, through the damper assembly 80, around the radially outer extension 22 of the turbine 20, between the turbine 20 and the impeller 18, and around the stator 26 to the fluid outlet.

[0015] Fig. Figure 2b shows the fluid flow through the torque converter 10 when the clutch is disengaged, whereby the friction material 24 on the radially outer extension 22 of the turbine 20 is not pressed against the radially extending section of the impeller housing 16. According to Fig. 2b The fluid pushes the turbine 20 away from the impeller 18 and flows radially outwards between the friction material 24 and the impeller housing 16. When the lock-up clutch is disengaged, the fluid flows between the impeller hub 84 and the drive shaft 82 of the gearbox along both radial sides of a stator shaft 86 through a gap formed by an axial surface 88 of the thrust bearing 34 and an axial surface 90 of the section 37 of the impeller housing 16, between the turbine 20 and the impeller 18, radially outwards around the radially outer extension of the turbine 20, back through the damper assembly 80 and axially through the inside of the drive shaft 82 of the gearbox to the fluid outlet.As the fluid flows through the gap formed by the axial surface 88 of the axial bearing 34 and the axial surface 90 of the impeller 18, a fluid film forms on the axial surface 88, which generates a sufficiently large force to exceed the thrust force of the stator 26 and prevent contact between the axial surface 88 of the axial bearing 34 and the axial surface 90 of the impeller 18.

[0016] Fig. Figure 3a shows a perspective view of the axial bearing 34 for use between the stator 26 and the impeller housing 16 according to an embodiment of the present invention. According to this embodiment, the axial bearing 34 is formed from unhardened aluminum and accordingly includes an unhardened aluminum pressure surface 36. The axial bearing 34 comprises a plurality of repeating circumferential sections 41, each containing a first or groove section 42 with a groove 44 extending from an inner circumferential surface 46 of the axial bearing to an outer circumferential surface 48 of the axial bearing 34, wherein a second or flat section 50 comprises a flat surface 52 of uniform thickness and a third or inclined section 54 comprises an inclined surface 56 arranged around the circumference between the groove 44 and the flat surface 52. The thickness of the inclined section 54 decreases in the circumferential direction on the way from the flat surface 52 to the groove 44.The second or flat section 50 has a first circumferential length L1, and the third section 54 has a second circumferential length L2, the first circumferential length L1 being smaller than the second circumferential length L2. The second section 50 and the third section 54 together have a total circumferential length LT (LT = L1 + L2). To form an optimal fluid film on the axial bearing surface 36, according to preferred embodiments, the circumferential length L1 of the flat section 50 constitutes 20% to 30% of the total circumferential length LT (0.20 to 0.30*LT), and the circumferential length L2 of the inclined section 54 constitutes 70% to 80% of the total circumferential length LT. In this case, the circumferential length refers to the mean circumferential length, i.e., the circumferential length at a mean radius M of the axial bearing 34.

[0017] Fig. Figure 3b shows a cross-sectional view of the axial bearing 34 along the section line AA in Fig. 3a with a printing area of ​​36. Fig. Figure 3b shows that a first or groove section 42 has a first thickness T1, a flat section 50 has a second thickness T2, and an inclined section 54 has a variable thickness that decreases circumferentially along the inclined surface 56 from the flat surface 52 to the groove 44, from the second thickness to a third thickness T3. According to this embodiment, the inclined surface 56 is inclined at an angle θ of less than 1°, preferably between 0.30° and 0.42°.

[0018] Fig. Figure 4a shows a perspective view of an axial bearing 134 for use between the stator 26 and the impeller housing 16 according to another embodiment of the present invention. Fig. Figure 4b shows a cross-sectional view of the axial bearing 134 along the section line BB in Fig. 4a. The thrust bearing 134 comprises a bearing surface 136 and is essentially constructed like the thrust bearing 34, with a plurality of repeating circumferential sections 141, each containing a groove section 42 and an inclined section 54. The only difference compared to the thrust bearing 34 is that the thrust bearing 134, instead of the flat section 50, comprises a flat section 150 with a flat surface 152 formed from an abrasion-resistant material 158. According to a preferred embodiment, the abrasion-resistant material 158 is an abrasion-resistant plastic, for example, a polyetheretherketone (PEEK) or a polyamide-imide manufactured by TORLON. The abrasion-resistant material 158 can be applied to the unhardened aluminum of the thrust bearing 34 by means of an adhesive.In order to form the flat surface 152, the abrasion-resistant material 158 can be applied, slots 160 extending from the inner circumferential surface 46 to the outer circumferential surface 48 can be milled into the flat section 150 and a strip of the material 158 can be applied to the bearing 34 in each of the slots 160.

[0019] Fig. Figure 5 shows a stator 226, which is manufactured as a single piece together with a thrust bearing 234 on the stator. The only difference between the thrust bearing 234 and the thrust bearing 34 is that the thrust bearing and the stator 26 are not separate parts, but rather that the thrust bearing 234 is manufactured as a single piece together with the stator 226.

[0020] Fig. Figure 6 shows a side cross-sectional view of a torque converter 310 according to another embodiment of the present invention, and Fig. Figure 7 shows an enlarged view of an axial bearing area of ​​the torque converter 310. The torque converter 310 is essentially constructed in the same way as the torque converter 10, except that the torque converter 310 contains only one axial bearing 334, which is arranged axially on a turbine side of a stator 326 between the stator 326 and a turbine 320, which in turn is attached to a damper 340. The axial bearing 334 can be constructed in the same way as the axial bearings 34, 134 and is connected to the stator 326 by a centering disk 330, which holds a freewheel clutch 328 in its position inside the stator 326. The axial bearing 334 includes an axial bearing surface 336, which can be formed in the same way as one of the axial bearing surfaces 36, 136 and faces the turbine 320. More precisely, the axial bearing surface 336 is axially oriented towards an axial surface of a radially extending section 350 of a turbine housing 352 of the turbine 320.The radially extending section 350 extends radially inwards from a rounded section 352, which holds the blades 354 of the turbine 320. The bearing surface 336 is shaped to maintain a lubricating film that prevents contact between the bearing surface 336 and the turbine housing 352. The lubricating film ensures a sufficiently high pressure between the turbine housing 352 and the stator so that the force generated by the pressure of the lubricating film during operation exceeds the thrust force of the stator 326 towards the turbine 320.

[0021] Fig. Figure 7 schematically shows that the axial bearing 334 can be attached to the centering disk 330 by a snap-fit ​​connection and can include a rotation-resistant feature, which can be manufactured as one piece with the snap-fit ​​connection or arranged separately from it. The rotation-resistant feature 338 can be a pin or a lug on the axial bearing 334 that can bear a larger load and is inserted into a hole in an adjacent surface or plane of the centering disk 330.

[0022] Fig.Figure 8 shows an enlarged view of an axial bearing area of ​​a torque converter 410 according to another embodiment of the present invention. The torque converter 410 is essentially constructed in the same way as the torque converter 310, except that the torque converter 4120 contains only one axial bearing 434, which is held axially between the turbine 420 and a stator 426 on a radially extending section 450 of a turbine housing 452 of a turbine 420. The axial bearing 434 can be constructed in the same way as the axial bearings 34, 134 and includes an axial bearing surface 436, which can be formed in the same way as one of the axial bearing surfaces 36, 136 and faces the stator 426. More precisely, the axial bearing surface 436 faces axially towards a centering disk 430, which holds a freewheel clutch 428 in its position inside the stator 426.The bearing surface 436 is shaped to maintain a lubricating film in order to prevent contact between the bearing surface 436 and the stator 426, in particular the centering disk 430. The lubricating film ensures a sufficiently high pressure between the turbine housing 452 and the stator 426 such that the force generated by the pressure of the lubricating film during operation exceeds the thrust force of the stator 426 in the direction of the turbine 420.

[0023] The axial bearing 434 can be attached to the radially extending section 450 by a snap-fit ​​connection and may include a rotation-resistant feature 438, which may be manufactured as a single piece with the snap-fit ​​connection or arranged separately. The rotation-resistant feature 438 may be a pin or a lug on the axial bearing 434 that can bear a larger load and engages in a hole in an adjacent surface or plane of the radially extending section 450.

[0024] In the preceding description, the invention has been described with reference to certain exemplary embodiments and their examples. However, it is clear that various modifications and changes can be made to these without deviating from the broader essence and scope of protection of the invention, which are set out in the following claims. Accordingly, the description and the drawings should not be regarded as a limitation, but rather as an illustration.

Claims

[1] Torque converter (10) comprising: a wheel (18) containing a wheel housing (16); a turbine (20) containing a turbine casing (352); and a stator (26) axially between the turbine (20) and the impeller (18), wherein a first fluid flow is generated between the impeller (18) and the stator (26) and a second fluid flow is generated between the turbine (20) and the stator (26); and an axial bearing (34) axially between the impeller (18) and the stator (26) or axially between the turbine (20) and the stator (26), wherein the axial bearing (34) includes a bearing surface (36) which serves to maintain a lubricating film on it in a region of the first fluid flow or the second fluid flow during operation of the torque converter (10). wherein the axial bearing (34) comprises a plurality of circumferential sections (41), each circumferential section (41) comprising a first section (42) with a groove (44) extending from an inner circumferential surface (46) of the axial bearing (34) to the outer circumferential surface (48) of the axial bearing (34), a second section (50) comprising a flat surface (52) of uniform thickness, and a third section (54) comprising an inclined surface (56) extending around the circumference between the groove (44) and the flat surface (52), wherein the thickness of the third section (54) gradually decreases along the inclined surface (56) around the circumference from the flat surface (52) to the groove (44). decreases, wherein the flat surface (52) is formed by an abrasion-resistant material (158) which is housed in a slot (160) of the second section (50) of the axial bearing (34). [2] Torque converter (10) according to claim 1, wherein the second section (50) has a first circumferential length (L1) and the third section (54) has a second circumferential length (L2), wherein the first circumferential length (L1) is smaller than the second circumferential length (L2). [3] Torque converter (10) according to claim 2, wherein the second section (50) and the third section (54) together have a total circumferential length (LT), wherein the first circumferential length (L1) constitutes 20% to 30% of the total circumferential length (LT) and the second circumferential length (L2) constitutes 70% to 80% of the total circumferential length (LT). [4] Torque converter (10) according to claim 1, wherein the abrasion-resistant material (158) is attached in the slot (160) by means of an adhesive. [5] Torque converter (10) according to claim 1, wherein the abrasion-resistant material (158) is a plastic. [6] Torque converter (10) according to claim 5, wherein the plastic is a polyetheretherketone or a polyamide-imide. [7] Method for forming a torque converter (10), the method comprising: Providing an axial bearing surface (36) in a first region of the fluid flow axially between an impeller (18) and a stator (26) or in a second region of the fluid flow between a turbine (20) and the stator (26) such that, during operation of the torque converter (10), a lubricating film is maintained by a fluid flow in the first region of the fluid flow or in the second region of the fluid flow. wherein the axial bearing surface (36) is formed on an axial bearing (34) which contains a plurality of circumferential sections (41), each circumferential section (41) having a first section (42) with a groove (44) extending from an inner circumferential surface (46) of the axial bearing (34) to the outer circumferential surface (48) of the axial bearing (34), a second section (50) containing a flat surface (52) of uniform thickness, and a third section (54) containing an inclined surface (56) across the circumference between the groove (44) and the flat surface (52), wherein the thickness of the third section (54) gradually decreases along the inclined surface (56) across the circumference from the flat surface (52) to the groove (44), wherein the method comprises: milling a slot (160) into the second section (50) of the axial bearing (34) to form a slot (160), and introducing an abrasion-resistant material (158) to form the flat surface (52). [8] Method according to claim 7, wherein the second section (50) has a first circumferential length (L1) and the third section (54) has a second circumferential length (L2), wherein the first circumferential length (L1) is smaller than the second circumferential length (L2). [9] Method according to claim 8, wherein the second section (50) and the third section (54) together have a total circumferential length (LT), wherein the first circumferential length (L1) constitutes 20% to 30% of the total circumferential length (LT) and the second circumferential length (L2) constitutes 70% to 80% of the total circumferential length (LT). [10] Method according to claim 7 wherein the insertion of an abrasion-resistant material (158) into the slot (160) includes applying the abrasion-resistant material (158) by means of an adhesive. [11] Method according to claim 7, wherein the abrasion-resistant material (158) is a plastic. [12] Method according to claim 11, wherein the plastic is a polyetheretherketone or a polyamide-imide.

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