Torque converter with a flexible mounting surface on the turbine wheel or the pump wheel

Abstract

Hydrodynamic torque converter (120) comprising the following: - a pump wheel (110) and a turbine wheel (115) which are rotatably mounted about a common axis of rotation (105); - a fluid (130) in a region between the pump wheel (110) and the turbine wheel (115); - wherein a first axial contact surface (165) is formed on the pump impeller (110) and a second axial contact surface (170) is formed on the turbine impeller (115); - so that a frictional connection can be formed between the pump wheel (110) and the turbine wheel (115) when the pump wheel (110) and the turbine wheel (115) are pressed axially against each other, - wherein one of the contact surfaces (165, 170) is designed to be flexible in order to conform to the other contact surface (165, 170) under axial pressure load, - wherein the flexible mounting surface (165, 170) comprises a sheet which is folded over all around, characterized in that the sheet is thinned in the area of ​​a bending edge of the fold (205).

Description

[0001] The invention relates to a torque converter. In particular, the invention relates to a hydrodynamic torque converter in a device for transmitting torque.

[0002] In a drive train, for example on board a motor vehicle, a device for transmitting torque is provided. The device is located between a drive engine and a transmission and comprises a hydrodynamic torque converter. The torque converter is formed by a pump wheel and a turbine wheel, which are mounted for rotation about a common axis of rotation. A fluid, usually an oil, is held between the two wheels of the torque converter, fluid-dynamically coupling the two wheels. The greater the speed difference between the two wheels, the more torque is transmitted between them. The torque converter can be used, for example, to assist a starting or stopping process of the aforementioned motor vehicle.

[0003] To reduce slippage between the impeller and the turbine wheel, a lock-up clutch is provided, designed as a friction clutch. For this purpose, the impeller and the turbine wheel each have an axial contact surface that is axially opposite each other. When the two wheels are pressed axially against each other, the contact surfaces engage and form a frictional connection.

[0004] For smooth, low-loss, and comfortable operation of the torque converter, the two contact surfaces must be precisely aligned. An axial offset, imbalance, or wobbling movement of one of the contact surfaces relative to the rotational axis can, for example, compromise the load-bearing behavior, control behavior, or fatigue strength of the torque converter.

[0005] Hydrodynamic torque converters with a lock-up clutch are known from the publications DE 11 2015 003 225 B4, DE 10 2014 218 154 A1 and DE 44 25 912 A1.

[0006] The object of the present invention is to provide an improved hydrodynamic torque converter. The invention achieves this object by means of the torque converter of independent claims 1 or 2. Subclaims specify preferred embodiments.

[0007] A hydrodynamic torque converter comprises a pump impeller and a turbine impeller, which are mounted for rotation about a common axis of rotation, and a fluid in a region between the pump impeller and the turbine impeller. A first axial contact surface is formed on the pump impeller and a second axial contact surface is formed on the turbine impeller, so that a frictional connection can be formed between the pump impeller and the turbine impeller when the pump impeller and the turbine impeller are pressed axially against each other. One of the contact surfaces is designed to be flexible so that it conforms to the other contact surface under axial compressive load.

[0008] The contact surfaces form a lock-up clutch for the torque converter. The torque converter with the lock-up clutch is sometimes also called an "Integrated Torque Converter" (iTC). In particular, the engagement and disengagement of the lock-up clutch can be smoother, more controlled, or more smoothly thanks to the flexible contact surface. Load-bearing behavior, adjustment behavior, axle offset, or wobble can be positively influenced by the flexibly mounted contact surface.

[0009] The turbine wheel is preferably connected radially outward to a housing in which the turbine wheel is housed. The housing encloses the fluid in the area of ​​the impeller. The contact surfaces are usually arranged on a radial outer side of hydrodynamic guide elements on the impeller or turbine wheel.

[0010] The flexible contact surface comprises a sheet metal with a circumferential fold. The fold preferably extends around the rotational axis, and the unloaded sheet metal typically forms a V-shape in longitudinal section. The sheet metal can be easily integrated with other elements of the impeller or turbine wheel. The circumferential fold makes it easy to create the flexibility of the contact surface.

[0011] It is preferred that the fold angle be less than 180°, so that the unloaded fold is open. The section of the sheet metal forming one of the contact surfaces can thus be elastically deformed more effectively when the pump wheel and the turbine wheel are pressed axially against each other.

[0012] The sheet metal can be thinned in the area of ​​a bending edge of the fold. This allows the rigidity of the contact surface to be maintained while simultaneously increasing the bendability or flexibility of the contact surface. By extending the effective bending length, the spring effect of the sheet metal can also be increased.

[0013] The sheet metal can be folded multiple times in alternating directions. In longitudinal section, the sheet metal can take on an S- or Z-shape, featuring multiple circumferential bending edges or folds, each of which can contribute to the flexibility of attaching the contact surface to the respective wheel.

[0014] In one embodiment, the flexible contact surface comprises a separate element connected to the pump or turbine wheel. This can facilitate the design of the pump or turbine wheel for its hydrodynamic function, while the separate element can facilitate the flexible attachment of the contact surface.

[0015] It is preferred that the separate element be connected to the pump or turbine wheel in a fluid-tight manner. This can, in particular, provide improved support for a torque converter embodiment in which one of the wheels simultaneously represents a hydraulic piston that generates the axial contact force between the pump wheel and the turbine wheel.

[0016] The abutting contact surfaces can enclose a predetermined angle with the rotational axis. This angle can, in particular, be 90°, so that the contact surfaces lie in the plane of rotation when pressed axially against each other. However, the contact surfaces can also enclose a different angle with the rotational axis when pressed against each other.

[0017] In a further embodiment, the abutting contact surfaces are spherically curved relative to the rotational axis. For example, one of the contact surfaces can be convex and the other concave.

[0018] In addition, a friction element can be attached to one or both contact surfaces. This can improve or adjust the engagement behavior of the contact surfaces.

[0019] The invention will now be described in more detail with reference to the accompanying figures, in which: Fig. 1 a longitudinal section through a device for transmitting torque with a torque converter; and Fig. 2-7 Variants of flexible contact surfaces on the torque converter from Fig. 1represent.

[0020] Fig. Figure 1 shows a longitudinal section through a device 100 for transmitting torque. The device 100 is designed in particular for use in a drive train, for example, of a motor vehicle. The device 100 can, in particular, be part of a torque converter, a dual clutch, a starting clutch, or a powershift clutch.

[0021] The device 100 comprises a rotational axis 105 around which a pump wheel 110 and a turbine wheel 115 of a hydrodynamic torque converter 120 are rotatably arranged. At a predetermined radial distance from the rotational axis 105, guide vanes 125 are formed on the pump wheel 110 and the turbine wheel 115, which are axially opposite one another. A fluid 130, typically an oil, is located in this area, which hydrodynamically couples the two wheels 110 and 115. An optional guide vane 135 is provided axially between the wheels 110, 115 to influence the flow of the fluid 130.

[0022] Preferably, the pump wheel 110 is connected on its radial outer side to a housing 140 which accommodates the turbine wheel 115 and the fluid 130.

[0023] The pump wheel 110 or the housing 140 represent an input side 145 of the device 100 for transmitting torque. An output side 150 can be directly or, as in Fig. 1, by means of an elastic element 155, to the turbine wheel 115 of the torque converter 120.

[0024] A lock-up clutch 160 is provided in a region that is preferably located radially outside the guide vanes 125. To form the lock-up clutch 160, a first axial contact surface 165 is formed on the pump wheel 110 and a second axial contact surface 170 is formed on the turbine wheel 115. The contact surfaces 165, 170 are axially opposite one another and can be brought into frictional engagement by moving the pump wheel 110 and the turbine wheel 115 axially toward one another or pressing them axially against one another.

[0025] In the illustrated, preferred embodiment, the turbine wheel 115 is designed to be axially movable relative to the pump wheel 110 and the housing 140. With respect to the fluid 130 in the housing 140, the turbine wheel 115 acts like a hydraulic piston, which is pressed axially toward the pump wheel 110 when the hydraulic pressure on the side axially facing away from the pump wheel 110 increases. When the housing 140 rotates about the rotational axis 105, the fluid 130 is pressed radially outward, creating such a hydraulic pressure. Therefore, starting at a predetermined rotational speed of the housing 140, the lock-up clutch 160 is hydraulically closed, so that the contact surfaces 165, 170 engage with one another and reduce slip between the pump wheel 110 and the turbine wheel 115, ideally to zero.

[0026] It is proposed to attach one of the contact surfaces 165, 170 flexibly, particularly with respect to the rotational axis 105, to the wheel 110, 115 assigned to it, so that the contact surfaces 165, 170 can nestle against one another more effectively when the lock-up clutch 160 is engaged. In the illustrated embodiment, the second contact surface 170 of the turbine wheel 115 is rigid or stiff with respect to the rotational axis 105, while the first contact surface 165 is connected to the pump wheel 110 or the housing 140 by means of a flexible element 175. As will be explained in more detail below, in another embodiment, the first contact surface 165 can be rigidly attached and the second contact surface 170 can be flexibly attached. The flexible element 175 can also be omitted if the respective contact surface 165, 170 is flexibly attached to the wheel 110, 115 assigned to it. A friction element 180 can optionally be provided on one of the contact surfaces 165, 170.

[0027] The surface along which the contact surfaces 165 and 170 engage when the two wheels 110, 115 are pressed axially against each other can be designed in different ways. For example, the surface can be flat and enclose a predetermined angle with the rotational axis 105. If this angle is 90°, the surface lies in the plane of rotation. Furthermore, the contact surfaces 165, 170 can also be designed to be concave and convex, corresponding to each other. Other superimposed and appropriate curvatures can also be used.

[0028] In general, it is preferable to design the contact surfaces 165 and 170 such that the least possible leakage occurs between the contact surfaces 165, 170, even when the lock-up clutch 160 is stationary or rotating at low speed. This facilitates the closing of the lock-up clutch 160 by building up hydraulic pressure of the fluid 130 under the influence of centrifugal force ("centrifugal oil"). When the lock-up clutch 160 is closed, the contact surfaces 165 and 170 can also be in fluid-tight contact with one another.

[0029] Fig. 2 to 7 show variants of flexible contact surfaces 165, 170 on the torque converter 120 of Fig. 1. All representations are schematic and each represent a possible embodiment of the above-mentioned with reference to Fig. 1 explained principle. Each of the Fig. 2 to 7 comprises an upper illustration, labelled A, showing the open lock-up clutch 160, and a lower illustration, labelled B, showing the closed lock-up clutch 160. The Fig. The variants shown in 2 to 7 are interconnected and with the Fig. 1. In principle, the first contact surface 165 and the second contact surface 170 can also be interchanged in all embodiments. Therefore, only one variant is described below; a person skilled in the art will readily recognize the mirror-image variant.

[0030] Fig. 2 shows an embodiment in which the second axial contact surface 170 is formed integrally on a sheet metal part that is part of the turbine wheel 115. The sheet metal part is bent circumferentially around the rotational axis 105, thereby forming a circumferential fold 205. Preferably, the fold angle between sections of the sheet metal part on different sides of the fold 205 is Fig. 2A) is less than 180°. In the area of ​​the fold 205, the sheet metal can be thinned, so that its material thickness is reduced. Due to the geometry of the arrangement, the effective bending length of the sheet metal can be extended, resulting in a further elastic effect of the sheet metal. The second contact surface 170 is faced by the sheet metal section that is further away from the rotation axis 105 along the sheet metal.

[0031] Fig. Figure 3 shows an embodiment based on this, in which two folds 205 are provided around which the sheet metal of the turbine wheel 115 is folded. The bending directions are opposite to each other, resulting in the Z-shaped fold shown. It is preferred that both fold angles be less than 180°.

[0032] Fig. 4 shows an embodiment similar to that of Fig. 1, but the flexible element 175 is attached to the turbine wheel 115. The flexible element 175 may in particular comprise a sheet metal.

[0033] Fig. 5 shows a further embodiment corresponding to that of Fig. 1.

[0034] Fig. Figure 6 shows a variant of the last-shown embodiment, in which the flexible element 175 is attached to the pump wheel 110 or the housing 140 and carries the first axial contact surface 165. The corresponding second contact surface 170 is rigidly mounted on the turbine wheel 115.

[0035] Fig. Figure 7 shows yet another embodiment similar to that of Fig. 4, but the contact surfaces 165, 170 ( Fig. 7B) lie in a plane of rotation around the axis of rotation 105. List of reference symbols 100 furnishings 105 axis of rotation 110 Pump wheel 115 Turbine wheel 120 torque converter 125 baffle 130 Fluid 135 Idler 140 housings 145 Entrance page 150 Output page 155 elastic element 160 lock-up clutch 165 first axial contact surface (on the impeller) 170 second axial contact surface (on the turbine wheel) 175 flexible element 180 friction element 205 fold

Claims

[1] Hydrodynamic torque converter (120) comprising: - a pump wheel (110) and a turbine wheel (115) which are rotatably mounted about a common axis of rotation (105); - a fluid (130) in a region between the pump wheel (110) and the turbine wheel (115); - wherein a first axial contact surface (165) is formed on the pump wheel (110) and a second axial contact surface (170) is formed on the turbine wheel (115); - so that a frictional connection can be formed between the pump wheel (110) and the turbine wheel (115) when the pump wheel (110) and the turbine wheel (115) are pressed axially against each other, - wherein one of the contact surfaces (165, 170) is designed to be flexible in order to conform to the other contact surface (165, 170) under axial pressure load, - wherein the flexible contact surface (165, 170) comprises a sheet which is folded all the way around, characterized bythat the sheet is thinned in the area of ​​a bending edge of the fold (205). [2] Hydrodynamic torque converter (120) comprising: - a pump wheel (110) and a turbine wheel (115) which are rotatably mounted about a common axis of rotation (105); - a fluid (130) in a region between the pump wheel (110) and the turbine wheel (115); - wherein a first axial contact surface (165) is formed on the pump wheel (110) and a second axial contact surface (170) is formed on the turbine wheel (115); - so that a frictional connection can be formed between the pump wheel (110) and the turbine wheel (115) when the pump wheel (110) and the turbine wheel (115) are pressed axially against each other, - wherein one of the contact surfaces (165, 170) is designed to be flexible in order to conform to the other contact surface (165, 170) under axial pressure load, - wherein the flexible contact surface (165, 170) comprises a sheet which is folded all the way around, characterized by that the sheet is folded several times in alternating directions. [3] Torque converter (120) according to claim 1 or 2, wherein the turbine wheel (115) is connected radially outwardly to a housing (140) in which the turbine wheel (115) is received. [4] Torque converter (120) according to one of the preceding claims, wherein the fold angle is less than 180°, so that the unloaded fold (205) is open. [5] Torque converter (120) according to one of the preceding claims, wherein the flexible contact surface (165, 170) comprises a separate element (175) connected to the pump wheel (110) or the turbine wheel (115). [6] Torque converter (120) according to claim 5, wherein the element (175) is fluid-tightly connected to the pump wheel (110) or the turbine wheel (115). [7] Torque converter (120) according to one of the preceding claims, wherein the abutting contact surfaces (165, 170) enclose a predetermined angle with the axis of rotation (105). [8] Torque converter (120) according to one of the preceding claims, wherein the abutting contact surfaces (165, 170) are spherically curved with respect to the axis of rotation (105). [9] Torque converter (120) according to one of the preceding claims, wherein a friction element (180) is attached to one of the contact surfaces (165, 170).

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