Drive unit for a comfort drive of a motor vehicle and comfort drive

Abstract

Drive unit (10) for a comfort drive of a motor vehicle, comprising an electric motor (1) having a drive shaft (5), with a toothing (6) arranged on the drive shaft (5) which interacts with a transmission element (27) arranged in an inner housing (22), wherein the transmission element (27) interacts with a drive element (35) having a longitudinal axis (36), wherein the transmission element (27) is configured to transmit a rotary motion of the transmission element (27) into a linear motion of the drive element (35), wherein the inner housing (22) is arranged in a receptacle (18) of an outer housing (15), and wherein the outer housing (15) forms an interface for connecting the drive unit (10) to a support structure (100) of a motor vehicle. wherein the transmission element (27) within the inner housing (22) is subjected to force in the direction of a stop surface (61) of the inner housing (22), wherein the force is applied to the transmission element (27) by a spring element (65), wherein the inner housing (22) consists of at least two housing elements (41, 42) which have a separating plane (46) arranged perpendicular to the longitudinal axis (36), that in at least one of the housing elements (41, 42) a further receptacle (25) for the transmission element (27) is formed, and that the further receptacle (25) has an extension in the direction of the longitudinal axis (36) which, when housing elements (41, 42) are connected to each other, generates a preload on the spring element (65) through the outer housing (15).

Description

State of the art

[0001] The invention relates to a drive unit for a comfort drive of a motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to a comfort drive with a drive unit according to the invention.

[0002] A drive device according to the preamble of claim 1 is known from the applicant's subsequently published DE 10 2015 215 428 A1. The known drive device is characterized by an inner housing that serves to accommodate a transmission mechanism. The transmission mechanism comprises a worm gear whose teeth interact with a drive shaft of an electric motor. A threaded spindle with its external thread is received in an internal thread in a longitudinal bore of the worm gear, so that a rotary movement of the worm gear is transmitted into a linear movement of the threaded spindle. The threaded spindle is, in turn, at least indirectly connected to the element to be adjusted, for example, a seat in a motor vehicle. Furthermore, the inner housing is received in the receptacle of an outer housing, which serves to attach the drive device to a support structure or to the body of the motor vehicle.Differently designed outer housings allow the same transmission mechanism, with the same inner housing, to be adapted to customer-specific mounting locations. The nested design of the worm gear, inner housing, and outer housing necessitates high-precision manufacturing of the individual components to achieve low-backlash transmission, which places correspondingly high demands on component manufacturing.

[0003] Furthermore, DE 10 2007 027 410 A1 discloses a drive device according to the preamble of claim 1, in which the worm gear is axially supported in an inner housing by a plurality of annular disks made of steel and plastic, which together form a thrust bearing. The thrust bearing of the worm gear serves to minimize friction within the inner housing. While the known thrust bearing allows the worm gear to be axially supported against the inner housing, the worm gear exhibits axial play within the inner housing. Although such axial play can, in principle, compensate for existing component tolerances, undesirable noise can occur, particularly when the direction of rotation of the drive is reversed, due to axial contact of the worm gear with the inner housing.

[0004] DE 10 2010 044 793 B4 and DE 10 2014 019 729 A1 each disclose spindle drives in which spindle nuts are mounted inside tubular housings, with the drive spindle protruding linearly from the tubular housing. Disclosure of the invention

[0005] The drive unit for a comfort drive of a motor vehicle with the features of claim 1 has the advantage that a compensation of component tolerances between worm gear, inner housing and outer housing of the drive unit is achieved while simultaneously optimizing operating characteristics, in particular in terms of low noise.

[0006] The invention is based on the idea of ​​arranging the worm wheel inside the inner housing with axial play (where the axial play refers to the play in the direction of the longitudinal axis of the transmission element or the worm wheel) and applying a force to the worm wheel in the direction of its longitudinal axis so that the worm wheel is always in contact with a surface of the inner housing.

[0007] Advantageous further developments of the drive device according to the invention for a comfort drive of a motor vehicle are listed in the dependent claims.

[0008] A particularly simple, cost-effective, and space-saving way to apply force to the transmission element or worm gear is by using a spring element in the form of a wave ring. The arrangement of the spring element between the worm gear and the inner housing depends on the direction of rotation of the drive. Therefore, in a reversible drive, it may be advisable or even necessary to provide a spring element on each side of the worm gear.

[0009] In a structurally preferred embodiment, which makes it possible to generate the desired force application during the assembly of the worm wheel and the spring element in the inner housing, it is proposed that the inner housing consists of at least two housing elements which have a separation plane arranged perpendicular to the longitudinal axis of the transmission element or the worm wheel, that the receptacle for the worm wheel is formed in at least one of the housing elements, and that the receptacle for the worm wheel has an extension in the direction of the longitudinal axis of the transmission element or the worm wheel which, when the housing elements are connected to each other, generates a preload on the spring element.In other words, this means that the inner housing in the area of ​​the worm gear has such dimensions that an axial gap is present whose axial extent is less than that of the spring element in the unloaded state, so that when the worm gear is installed in the inner housing, the spring element is arranged within the aforementioned axial gap under elastic preload and the worm gear is subjected to force in the direction of the inner housing.

[0010] To simplify the assembly of the housing elements, at least two housing elements can be connected to each other by a snap-fit ​​connection during a pre-assembly step. In particular, no separate fastening elements such as screws are required with such a housing design.

[0011] Furthermore, to minimize friction, especially with regard to the force exerted on the worm wheel in the inner housing, it is provided that the transmission element (worm wheel) is mounted in the inner housing in the direction of the longitudinal axis of the transmission element or the worm wheel with at least one axial bearing element interposed.

[0012] Optimization of the bearing arrangement or an increase in efficiency can be achieved in a reversible drive if an axial bearing element is provided on both sides of the transmission element.

[0013] A particularly simple and precise radial bearing arrangement for the worm gear is achieved if the worm gear has a sleeve-shaped bearing extension on both sides of a toothed area interacting with the output element, which is radially supported in a recess of the inner housing.

[0014] Finally, the invention also includes a comfort drive with a drive unit according to the invention as described so far. The comfort drive has the advantages mentioned in the description of the drive unit. Such a comfort drive can, in particular, but not limited to, be designed as a seat adjustment drive or a steering column drive.

[0015] Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing.

[0016] This shows in: Fig. 1. A perspective view of a drive unit for a comfort drive system of a motor vehicle, Fig. 2 a longitudinal section through a housing of the drive device according to Fig. 1 and Fig. 3 the components of the drive unit according to the Fig. 1 in an exploded view.

[0017] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0018] In the Fig. Figure 1 shows a drive unit 10 for a comfort drive system of a motor vehicle. Such a comfort drive system can, for example, be designed in the form of a seat adjustment drive or a steering column adjustment drive. However, the invention is not intended to be limited to such applications of the drive unit 10.

[0019] The drive unit 10 comprises an electric motor 1 with an exemplary metal housing in the form of a pole cup housing 2, manufactured by deep drawing, and a connection flange 3 with a plug connector 4 for electrical contacting the electric motor 1. The drive shaft 5 of the electric motor 1 protrudes from the pole cup housing 2 or the connection flange 3 ( Fig. 2) out. The drive shaft 5 has a worm gear 6 on the area protruding from the pole pot housing 2 or the connection flange 3.

[0020] The pole housing 2 of the electric motor 1, or its connection flange 3, is connected to an inner housing 22 of the drive unit 10. For this purpose, the connection flange 3 of the electric motor 1 is connected to a connection surface 16 of the inner housing 22 by means of screws 7 on the side where the drive shaft 5 protrudes from the connection flange 3. The inner housing 22, which is preferably made of plastic and manufactured by injection molding, is connected to an (outer) housing 15, also preferably made of plastic and manufactured by injection molding, which serves for a customer- and / or application-specific configuration of the drive unit 10 and its attachment to a support structure 100 of the motor vehicle (not shown in detail), for example, a body panel of the motor vehicle.Furthermore, the housing 15 also has, purely by way of example, through holes 17, via which the housing 15 can be fastened to the support structure 100 by means of screws (not shown).

[0021] Furthermore, the housing 15 features, for example, a large number of elongated recesses 20, which serve on the one hand to save weight and on the other hand form a relatively stiff or firm housing 15 that meets crash requirements in particular, despite the relatively low weight.

[0022] The inner housing 22 is received in the housing 15 in the area of ​​a receptacle 18 formed in the interior of the housing 15. Preferably, a positive-locking connection exists at least partially between the receptacle 18 of the housing 15 and an outer contour 19 of the inner housing 22, which may in particular be in the form of a bayonet connection. Furthermore, the receptacle 18, as can be seen in particular from the Fig. 2 can be seen to have at least a round shape in some areas, which, together with the opposite outer contour 19 of the inner housing 22, allows the inner housing 22 to pivot about an axis 26 of the housing 15 by a certain pivot angle.

[0023] The inner housing 22 serves to receive or support a worm gear 27, which acts as a transmission element and is part of a transmission mechanism 30. The worm teeth 6 of the drive shaft 5 of the electric motor 1, which projects into the inner housing 22, mesh with the (external) teeth of the worm gear 27. The worm gear 27 has a through-hole formed as an internal thread 31. The internal thread 31 of the worm gear 27 interacts with an external thread 32 of an actuating rod 35 in the form of a threaded spindle, such that when the worm gear 27 is rotated about a longitudinal axis 36 of the internal thread 31, which coincides with the longitudinal axis of the actuating rod 35, a linear movement of the actuating rod 35 occurs in the direction of the double arrow 38.

[0024] The actuating rod 35, which serves as a drive element, has a fastening section 39 with an opening 40 at one end area, in the area of ​​which an adjustable element can be connected to the fastening rod 35.

[0025] How best to draw from a synthesis of the Fig. 2 and Fig. As can be seen in Figure 3, the inner housing 22 consists of two housing elements 41, 42, which can be connected to each other by means of a snap-fit ​​connection 43 during a pre-assembly step. The two housing elements 41, 42 form a further receptacle 25 for the worm gear 27 or the transmission mechanism 30. The two end faces 44, 45 of the two housing elements 41, 42, which abut each other when connected, form a parting plane 46 that runs perpendicular to the longitudinal axis 36 of the actuating rod 35 or the worm gear 27. Furthermore, each of the two housing elements 41, 42 has a through-opening 47, 48 through which the actuating rod 35 projects, which in turn passes through the housing 15 in the area of ​​through-openings 49, 50.

[0026] The two through-openings 47, 48 of the two housing elements 41, 42 simultaneously serve for the radial support of the worm gear 27. For this purpose, the worm gear 27 has, on both sides of its toothed area 51, an annular bearing extension 52, 53 extending coaxially to the longitudinal axis 36, which is radially received in the respective through-opening 47, 48 and rotatably mounted there. Furthermore, it can be seen from the Fig. 2 and Fig. 3. It can be seen that on both sides of the toothed area 51 of the worm gear 27, a thrust washer 57, 58, of particularly identical design, bears axially against a stepped, radially circumferential shoulder 54 of the worm gear 27. The worm gear 27 is axially supported on an inner first stop surface 61 of the inner housing 22 via one of the thrust washers 57.

[0027] An axial stop 59 connected to the actuating rod 35 limits the axial movement of the actuating rod 35 on the side of the actuating rod 35 opposite the fastening section 39.

[0028] On the side of the gear area 51 opposite the thrust washer 57, a spring element 65 in the form of a wave ring 66 is arranged between the thrust washer 58 and a second stop surface 62 in the area of ​​the end face 44 of the inner housing 22. The wave ring 66 is supported between the second stop surface 62 and the thrust washer 58, which is in contact with it, and exerts a force F on the spindle nut 27 directed towards the thrust washer 57, which is aligned with the longitudinal axis 36. The force F constantly presses the worm gear 27 axially against the first stop surface 61 of the inner housing 22, with the thrust washer 57 acting as an intermediary.

[0029] To generate the force F or a corresponding preload force by the wave ring 66, an axial gap 67 is formed between the thrust washer 58 and the second stop surface 62 in the further receptacle 25 of the inner housing 22. The width b of this gap is less than the corresponding axial extent of the wave ring 66 in the relaxed, i.e., not mounted in the inner housing 22, preloaded state. This allows the worm gear 27 to be first mounted with the thrust washer 57 in one housing element 41 of the inner housing 22 during the assembly of the transmission mechanism 30. The other thrust washer 58 and the wave ring 66 are then mounted. During this process, the wave ring 66 initially projects beyond one end face 45 of the housing element 41. When connecting the (outer) housing 15 with the two housing elements 41, 42, the wave ring 66 is axially pressed between the housing elements 41, 42, thereby generating the force F.Furthermore, a tension is achieved between the housing elements 41 and 42 and the housing 15.

[0030] The drive device 10 described so far can be adapted or modified in a variety of ways without deviating from the inventive concept. In particular, it is conceivable not only to provide a spring element 65 or a wave ring 66 on one side of the worm gear 27, but to provide a corresponding arrangement on both sides of the toothed area 51.

Claims

[1] Drive unit (10) for a comfort drive of a motor vehicle, comprising an electric motor (1) having a drive shaft (5), with a toothing (6) arranged on the drive shaft (5) which interacts with a transmission element (27) arranged in an inner housing (22), wherein the transmission element (27) interacts with a drive element (35) having a longitudinal axis (36), wherein the transmission element (27) is configured to transmit a rotary motion of the transmission element (27) into a linear motion of the drive element (35), wherein the inner housing (22) is arranged in a receptacle (18) of an outer housing (15), and wherein the outer housing (15) forms an interface for connecting the drive unit (10) to a support structure (100) of a motor vehicle, wherein the transmission element (27) within the inner housing (22) is subjected to force in the direction of a stop surface (61) of the inner housing (22), wherein the force is applied to the transmission element (27) by a spring element (65), wherein the inner housing (22) consists of at least two housing elements (41, 42) which have a separating plane (46) arranged perpendicular to the longitudinal axis (36), that in at least one of the housing elements (41, 42) a further receptacle (25) for the transmission element (27) is formed, and that the further receptacle (25) has an extension in the direction of the longitudinal axis (36) which, when housing elements (41, 42) are connected to each other, generates a preload on the spring element (65) through the outer housing (15). [2] Drive device according to claim 1, characterized by , that the direction of the force application to the transmission element (27) is in the direction of the longitudinal axis (36) of the drive element (35). [3] Drive device according to claim 1 or 2, characterized by , that the spring element (65) is designed as a wave ring (66) [4] Drive device according to claims 1 to 3, characterized by , that the two housing elements (41, 42) each have a through-opening (47, 48) through which the actuating rod as drive element (35) protrudes, which in turn crosses the housing (15) in the area of ​​through-openings (49, 50). [5] Drive device according to claim 4, characterized by , that the two through-openings (47, 48) of the two housing elements (41, 42) simultaneously serve for the radial support of the transmission element (27) designed as a worm gear. [6] Drive device according to claims 1 to 5, characterized by , that the at least two housing elements (41, 42) are connected to each other by a snap-fit ​​connection (43) for pre-assembly. [7] Drive device according to any one of claims 1 to 6, characterized by , that the transmission element (27) is mounted in the inner housing (22) with at least one axial bearing element (57, 58) interposed. [8] Drive device according to claim 7, characterized by , that an axial bearing element (57,58) is provided on both sides of the transmission element (27). [9] Drive device according to any one of claims 1 to 8, characterized by , that the worm gear (27) has on both sides of a toothed area (51) cooperating with the toothing (6) of the drive shaft (5) a sleeve-shaped bearing extension (52, 53) which is radially mounted in each of the through-openings (47, 48) of the inner housing (22). [10] Comfort drive with a drive unit (10) in the form of a seat adjustment drive or a steering column adjustment drive according to one of claims 1 to 9.

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