Assembly for transmitting torque

Abstract

The invention relates to an assembly (1) for transmitting torque, comprising a first component (2) and a second component (7), wherein a press connection is formed between the first component (2) and the second component (7), and the first component (2) has a lower hardness than the second component (7), at least in the region of the press connection. The second component (7) consists of a sintered material and has a toothing (19) in the region of the press connection.

Description

[0001] The invention relates to an assembly for transmitting a torque, in particular a synchronizing device or clutch device, comprising a first component and a second component, wherein a press connection is formed between the first component and the second component, and the first component has a lower hardness than the second component, at least in the region of the press connection.

[0002] Furthermore, the invention relates to a method for forming a press connection between a first component and a second component for forming an assembly, wherein a component is used as the first component which has a lower hardness than the second component, at least in the region of the press connection.

[0003] To transmit torque from rotating shafts to components, longitudinal or transverse press connections, splines or keyways are usually used as shaft-hub connections. Due to geometric conditions (e.g. in the case of a shaft with a shoulder), it is often not possible or only very complex to manufacture a spline. A pure press connection without positive locking is often not sufficient due to the load situation to transmit the applied torque without slipping. Knurled press connections represent a special type of shaft-hub connection. They are characterized by a combination of friction and positive locking mechanisms for load transmission. This allows very high torsional loads to be transmitted compared to conventional, purely friction or positive locking connections. Knurled press connections are used to create a connection between joining partners made of solid materials, ieCast materials or forged materials, because high joining forces can be generated through material displacement during joining. A knurled outer surface of the first joining partner is pushed onto a cylindrical surface of the second joining partner with a radial overlap of at least 0.1 mm. The hardness of the joining partners is selected such that the hardness of the joining partner with the knurl is at least 15% higher than the hardness of the component that does not have a knurled surface. This causes the knurl to groove into the softer material.

[0004] A spline for forming a torque-transmitting assembly is known, for example, from AT 520 015 A1. This document describes an assembly comprising a first component with internal teeth and a second component with external teeth, wherein the two components can be connected to one another by a press fit formed between the internal and external teeth, and wherein the internal and external teeth each have a plurality of teeth, the teeth of the internal toothing of the first component and / or the teeth of the external toothing of the second component have recesses along the tooth flanks. The tooth geometry with the recess can significantly reduce the stress level in the teeth of the spline. This makes it possible to shift the overlap for forming the press fit out of the critical area, whereby the load on the material itself can be reduced.

[0005] The object of the present invention is to create a possibility with which a high torque can be transmitted using components with complex geometry without great manufacturing effort.

[0006] To solve the problem, the assembly mentioned at the beginning provides that the second component consists of a sintered material and has a toothing in the area of the press connection.

[0007] Furthermore, the object is achieved with the method mentioned at the outset, according to which a component made of a sintered material is used as the second component, wherein a toothing is formed on the second component in the region of the press connection, which toothing has a density which is between 85% and 98% of the full density of the material of the second component, and that the two components are then pressed together in the region of the toothing.

[0008] One advantage of this is that the production of the second component can be carried out more easily using a powder metallurgy process, as is well known. By using a sintered component in a torque-transmitting assembly, manufacturing tolerances of the component can be compensated for or evened out over the circumference of the press fit due to its porosity. This can significantly reduce variations in the transmittable torque during the press fit with the second component made of sintered material. Furthermore, due to the improved pressability of the sintered component due to its porosity, the first component can be pressed in with less radial expansion.

[0009] To further improve these effects, according to embodiments of the invention, the gearing can have teeth with a radial tooth height between 100 µm and 800 µm, and / or the gearing can have a tooth pitch selected from a range of 0.5 mm to 2 mm. The use of such "micro-toothing" allows for better compensation of geometric differences across the circumference. Furthermore, the relatively high surface area in the area of the gearing can improve the frictional or positive engagement, thus increasing the transmittable torque.

[0010] According to a further embodiment of the invention, the first component is a receiving element for a drive element, and the second component is a synchronizer hub or a coupling body of the synchronization device or a coupling element in a disconnect device of a motor vehicle. The type of connection between the two components in this application enables a reduction in the size of the assembly and thus better integration into a larger unit, such as a drive train. On the other hand, this also makes it easier to withstand a high torque increase in a short period of time, as can be the case, particularly, in electric drives.

[0011] To simplify the production of the press connection, according to another embodiment of the invention, it can be provided that the toothing is formed only in a section of the entire axial length of the contact surface between the first and the second component.

[0012] Furthermore, according to one embodiment variant, the second component can be designed with a cross-sectional widening in a section adjacent to the toothing. This cross-sectional widening can be used to guide the first component within the second component during the formation of the press fit, so that the toothing on the second component is subjected to more even stress. In particular, tilting of the components and, as a result, excessive pressing with corresponding undesired material displacement can be avoided.

[0013] In order to improve or even out the compaction of the toothing on the second component during the formation of the press fit, according to an embodiment variant of the invention, it can be provided that the toothing is calibrated before being pressed on.

[0014] According to a further embodiment of the invention, calibration can be performed using a rolling tool. By using a rolling tool, the lower compression of the gear teeth can be more easily achieved before the press fit is formed, since the extent to which the rolling tool influences the gear teeth can be adjusted by adjusting the feed of the rolling tool to the gear teeth.

[0015] For a more uniform calibration of the teeth of the gearing, according to an embodiment variant of the invention, it can be provided that the gearing is designed as cycloidal gearing, in particular as involute gearing, since this allows the tooth flanks of the teeth of the gearing to be reached more uniformly with the rolling tool over at least approximately the entire height of the tooth flanks.

[0016] For a better understanding of the invention, it is explained in more detail with reference to the following figures.

[0017] They show in a simplified, schematic representation: Fig. 1 shows a section of a variant of a coupling device in an oblique view; Fig. 2 a section of a variant of a synchronizing device in longitudinal section; Fig. 3 shows a section of a variant embodiment of a second component of the assembly according to the invention; Fig. 4 a section of another embodiment of a second component of the assembly according to the invention.

[0018] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations, whereby the disclosures contained in the entire description can be applied mutatis mutandis to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and in the event of a change in position, these positional information must be applied mutatis mutandis to the new position.

[0019] In Fig. 1 shows a variant of an assembly 1 in the form of a coupling device in an oblique view in the engaged position.

[0020] The assembly 1 serves to transmit torque from a first component 2 in the form of a first (primary) drive element (e.g., a first shaft) to a second (secondary) drive element 3 (e.g., a second shaft). In the illustrated embodiment, the first component 2 encompasses one end of the second drive element 3, with a bearing 4 arranged between the first component 2 and the second drive element 3, so that the first component 2 and the second drive element 3 can rotate relative to one another about a rotation axis 5 in the disengaged state.

[0021] For the rotationally fixed connection of the first component 2 to the second drive element 3, the assembly 1 has a sliding sleeve 6, a second component 7 in the form of a synchronous hub and a coupling body 8.

[0022] Alternatively or additionally, the second drive element 3 can also form a first component 2 and the coupling body 8 a second component 7. The following explanations regarding the press connection between the first and the second component 2, 7 can therefore alternatively or additionally also apply to these elements of the coupling device (according to Fig. 1) can be applied.

[0023] The coupling body 8 is connected in a rotationally fixed manner to the second drive element 3 and has a corresponding receptacle 9 (e.g., in the form of an axial bore) for the second drive element 3. The coupling body 8 has external teeth on a radially outer surface 10.

[0024] The second component 7 is connected to the first component 2 in a rotationally fixed manner and, for this purpose, has a receptacle 11 (e.g., in the form of an axial bore) for the first drive element 2. In addition, the first component 2 can have a web 12 on a radially outer surface, in particular extending around the entire circumference, against which the second component 7 can bear.

[0025] The second component 7 also has external teeth on a radially outer surface 13. Furthermore, the second component 7 is arranged next to the coupling body 9 in the direction of the rotation axis 5.

[0026] The external teeth of the coupling body 8 and the external teeth of the second component 7 are formed at the same radial height.

[0027] The sliding sleeve 6 is arranged radially above the second component 7. It has an internal toothing 14 on a radially inner surface. The internal toothing 14 is in constant engagement with the external toothing of the second component 7.

[0028] The sliding sleeve 6 is arranged to be axially displaceable in the direction of the rotation axis 5. In the Fig. In the engaged position shown in Figure 1, it is pushed over the coupling body 8, so that the internal toothing 14 of the sliding sleeve 6 also engages with the external toothing of the coupling body 9. Thus, the first component 2 and the second drive element 3 are connected to one another, allowing torque to be transmitted.

[0029] For the disengaged position of the sliding sleeve 6, this is shown in Fig. 1 is shifted to the right, so that the internal toothing 14 of the sliding sleeve 6 comes out of engagement with the external toothing of the coupling body 9 and only engages with the external toothing of the second component 7.

[0030] Such a coupling device can be used, for example, in a disconnect device of an electric drive of a motor vehicle (hybrid or fully electric) for connecting or disconnecting an electric motor or an additional electric motor. However, the coupling device can also be used for another purpose, for example, for connecting or disconnecting an all-wheel drive. It should also be noted that the Fig. 1 The coupling device shown in concrete terms is only exemplary.

[0031] In Fig. Figure 2 shows a section of a variant of assembly 2 in the form of a synchronizing device in an oblique view. This can be used, for example, in an electric axle of a motor vehicle or in other applications in which a synchronizing device, in particular a locking synchronizer, is used.

[0032] The assembly 2 comprises the first component 2 in the form of a first receiving element for a first drive element (not shown), such as a first shaft or a first axle, and a second receiving element 15 for a second drive element separable from the first component 2, such as a second shaft or a second axle. Furthermore, the synchronizing device 4 comprises the annular sliding sleeve 6, a synchronizer ring 16, the second component 7 in the form of an annular synchronizer hub, and the annular coupling body 8.

[0033] Alternatively or additionally, the second receiving element 15 can also form a first component 2 and the coupling body 8 a second component 7. The following explanations regarding the press connection between the first and the second component 2, 7 can therefore alternatively or additionally also apply to these elements of the synchronizing device (according to Fig. 2) are applied.

[0034] The coupling body 8 is connected to the second receiving element 15 in a rotationally fixed manner or is formed in one piece therewith and has an external toothing.

[0035] Likewise, the second component 7 has an external toothing, which, however, consists of the Fig. 2 is not visible. The second component 7 is arranged on the first component 2 and is connected thereto in a rotationally fixed manner. The second component 7 is arranged radially below the sliding sleeve 6.

[0036] The synchronizer ring 16 is arranged on the clutch body 8. The synchronizer ring 16 can have an external toothing with teeth on at least some sections of its outer circumference.

[0037] The external teeth of the clutch body 8 and the external teeth of the second component 7 as well as the external teeth of the synchronizer ring 16 are formed at the same radial height.

[0038] Conical surfaces and / or at least one conical element or at least one conical friction element can be arranged between the synchronizer ring 16 and the clutch body 8.

[0039] The sliding sleeve 6 is arranged axially displaceably in the assembly 2, so that it can be axially displaced from a first position, in which the two drive elements are not coupled to one another, into a second position, in which a torque transmission between the two drive elements is possible. Fig. 2 shows the second position of the sliding sleeve 6. Accordingly, the external teeth of the clutch body 8 and, if applicable, the synchronizer ring 16 and the external teeth of the second component 7 as well as the internal teeth 14 of the sliding sleeve 6 are coordinated with one another such that the internal teeth 14 of the sliding sleeve 6 can mesh with the external teeth of the second component 7 and, in the second position, also with the external teeth of the clutch body 8 (and, if applicable, the synchronizer ring 16).

[0040] Assembly 2 is designed as a single-sided locking synchronizer. However, it can also be designed as a double-sided locking synchronizer.

[0041] The assembly 2 can also be designed without the synchronizer ring 16.

[0042] In all variants of the assembly 1, a press connection is formed between the first component 2 and the second component 7. In the variant of the assembly according to Fig. 1, this is between an outer circumferential surface of the first component 2 in the section in which the second component 7 is arranged on the first component 2, and an inner circumferential surface 18 of the second component 7. Alternatively or additionally, the press connection can also be formed between the second drive element 3 and the coupling body 9, which also lie directly against one another, like the second component 7 on the first component 2.

[0043] In the version of assembly 1 according to Fig. 2, the lateral surface 17 is formed on the first receiving element (first component 2) and the lateral surface 18 on the synchronizer hub (second component 7) and / or a further / the lateral surface 17 on the second receiving element 15 and a further / the lateral surface 18 on the clutch body 8, as can be seen from Fig. 2 is evident.

[0044] It should be noted at this point that the first component 2 can also form the second component 7 and the second component 7 can form the first component 2. In the embodiments of the assembly 1 according to the Fig. 1 and Fig. 2, however, the first drive element or the first receiving element preferably form the first component 2, since these can be produced relatively easily by means of a casting process or a forging process or an extrusion process.

[0045] The first component 2 has a lower hardness than the second component 7. For example, the first component 2 can consist of a cast material, e.g. a steel, or a material which has no pores except for defects. The second material is a sintered material, i.e. the second component 7 is a sintered component. For example, the second material can be sintered steel. The second component 7 has pores due to its powder metallurgical production. The density of the second component 7 is therefore lower than the density of the first component. The density of the second component 7 after sintering is between 85% and 98% of the full density of the material of the second component 7, i.e. a cast material or forged material, at least in the area of the lateral surface 18 or in the area of the press connection.

[0046] The second component 7 has a hardness, at least in the area of the press connection, that is at least 15%, in particular in the range of 50% to 150%, greater than the hardness of the first component 2. As explained above, hardness differences of at least 15% are used for such press connections between solid material components. By using a sintered component as the second component 7, the advantage can be achieved that the press connection can also be formed with smaller hardness differences. However, for assembly 1, higher hardness differences than the specified minimum values can of course also be provided.

[0047] Furthermore, in assembly 1, the first and second components 2, 7 are also joined with a radial overlap. Preferably, the receptacle 11 of the second component 7, in which the first component 2, for example the synchronizer hub or the clutch body 9, is manufactured with a smaller inner diameter than would correspond to the outer diameter of the first component 2 in the region of this receptacle 11, is manufactured. The radial overlap can, for example, be at least 0.1 mm. However, due to the sintered component as the second component 7, larger radial overlaps of 0.2 mm and more, in particular between 0.2 mm and 0.75 mm, are possible.

[0048] The second component 7 has a toothing 19 with teeth 20 in the area of the press connection, as shown in detail in Fig. 3. The toothing 19 can be designed in the form of a knurl with axially parallel teeth 20. The teeth 20 can, for example, have an at least approximately triangular cross-section.

[0049] It is further possible that the first component 2 is designed with a knurling in the area of the press connection, which has teeth that can be pressed into the tooth gaps between the teeth 20 of the toothing 19 of the second component 7.

[0050] Furthermore, it is possible for the teeth 20 to be rounded at the tip and / or root diameter, so that the axial view of the tooth contour has a wave shape. The radius of the rounding can be between 0.01 mm and 0.3 mm, in particular between 0.01 mm and 0.2 mm. The rounded design offers advantages with regard to the strength of the toothing, particularly in the tooth root area.

[0051] According to one embodiment, the teeth 20 can have a radial tooth height 21 between 100 µm and 800 µm. In principle, the teeth 20 can also be higher than 800 µm in the radial direction.

[0052] It is further preferred if the toothing has a tooth pitch selected from a range of 0.5 mm to 2 mm, in particular from a range of 0.8 mm to 1.5 mm. The tooth pitch is determined by dividing the circumference in mm by the number of teeth (20).

[0053] As from Fig. 1, the press connection can be formed over the entire axial length of the second component 7. According to another embodiment, however, it can also be provided that the toothing 19 is formed only in a section of the entire axial length of the contact surface between the first and the second component 2, 7. This embodiment is shown in Fig. 2. In this case, the press connection preferably extends over at least 10%, in particular between 20% and 80%, of the entire axial length of this contact surface.

[0054] Also in Fig. 2 shows a variant embodiment in which the second component 7 has a cross-sectional widening in a section 22 adjoining the toothing 19. In the variant embodiment shown, a radially extending shoulder 23 is formed between the section 22 and the toothing 19, so that the contact surface between the two components 2, 7 is formed by a first cylindrical surface and a second cylindrical surface, wherein the second cylindrical surface is formed by a cylinder that has the larger diameter of the two cylinders.

[0055] The shoulder 23 can also be designed to run obliquely so that a truncated cone is formed between the two cylinders.

[0056] It should be noted that the geometric shapes mentioned refer to the internal geometry of the second component 7, which is applied to the first component 2, and not to an external geometry of the second component 7.

[0057] By forming the second component 7 as a sintered component with the toothing 19 in the region of the pressing surface to be formed with the first component 2, it can be achieved that when the first component 2 is axially pressed into the second component 7, the toothing 19 of the second component 7 is compacted in the region of the pressing surface to be formed. Advantageously, the first component 2 also has a toothing that engages with the toothing 19 of the second component 7 and thereby leads to at least a compaction of the tooth flanks of the toothing. However, the tooth roots and the area of the tooth gaps between the teeth 20 and / or the tooth tips of the teeth 20 are preferably also compacted during pressing.

[0058] To form the press connection, the sintered component, i.e., the second component 7, is manufactured using a conventional powder metallurgical process that includes the steps of powder pressing and sintering. The toothing 19 for forming the press connection is not further compacted after sintering, so it has a (relatively low) density that is between 85% and 98% of the full density of the material of the second component 7. However, other sections of the second component 7 can still be further compacted after sintering.

[0059] However, according to one embodiment, it can be provided that in order to increase the accuracy of the toothing 19 for forming the press connection, i.e. to reduce tolerances, calibration is carried out after sintering. In principle, any method known in powder metallurgy and suitable for toothing can be used for this purpose. According to one embodiment of the method, however, it can be provided that the calibration is carried out using a rolling tool. For this purpose, a gear wheel is used as the rolling tool, which has a highly precise toothing. This toothing is brought into mesh with the toothing 19 of the second component 7. It is advantageous if, according to one embodiment, the toothing 19 of the second component 7 is a cycloidal toothing, in particular an involute toothing, as can be seen from a tooth 20 in Fig. 4 is shown.

[0060] The invention can be used in torque transmission. Examples of this are mentioned above. In addition, assembly 1 can also be a parking lock, for example.

[0061] The exemplary embodiments show possible embodiments of the assembly 1 or the second component 7, whereby it should be noted at this point that combinations of the individual embodiments are also possible.

[0062] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure of assembly 1 or the second component 7, these are not necessarily shown to scale. List of reference symbols 1 assembly 2 component 3 Drive element 4 camps 5 axis of rotation 6 sliding sleeve 7 Component 8 coupling bodies 9 Recording 10 Shell surface 11 recording 12 jetty 13 Shell surface 14 Internal gearing 15 receiving element 16 Synchronizer ring 17 Shell surface 18 Shell surface 19 Gearing 20 teeth 21 Tooth height Section 22 23 Shoulder QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] AT 520 015 A1

[0004]

Claims

[1] Assembly (1) for the transmission of a torque, in particular a synchronizing device or clutch device, comprising a first component (2) and a second component (7), wherein a press connection is formed between the first component (2) and the second component (7), and the first component (2) has a lower hardness than the second component (7), at least in the region of the press connection, characterized by that the second component (7) consists of a sintered material and has a toothing (19) in the area of the press connection. [2] Assembly (1) according to claim 1, characterized by that the toothing (19) has teeth (20) with a radial tooth height (21) between 100 µm and 800 µm. [3] Assembly (1) according to claim 1 or 2, characterized by that the toothing (19) has a tooth pitch selected from a range of 0.5 mm to 2 mm. [4] Assembly (1) according to one of claims 1 to 3, characterized bythat the first component (2) is a receiving element for a drive element and the second component (7) is a synchronizer hub or a coupling body (8) of the synchronizing device or a coupling element in a disconnect device of a motor vehicle. [5] Assembly (1) according to one of claims 1 to 4, characterized by that the toothing (19) is formed only in a section of the entire axial length of the contact surface between the first and the second component (2, 7). [6] Assembly (1) according to one of claims 1 to 5, characterized by that the second component (7) is formed with a cross-sectional widening in a section (22) adjoining the toothing (19). [7] Method for forming a press connection between a first component (2) and a second component (7) for forming an assembly (1), wherein the first component (2) used is a component (2) which has a lower hardness than the second component (7), at least in the region of the press connection, characterized by that a component (7) made of a sintered material is used as the second component (7), wherein a toothing (19) is formed on the second component (7) in the region of the press connection, which toothing has a density which is between 85% and 98% of the full density of the material of the second component (7), and that the two components (2, 7) are then pressed together in the region of the toothing. [8] Method according to claim 7, characterized by that the toothing (19) is calibrated before pressing on. [9] Method according to claim 8, characterized by that the calibration is carried out with a rolling tool. [10] Method according to one of claims 7 to 9, characterized by that the toothing (19) is designed as cycloidal toothing, in particular as involute toothing.

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