Spindle drive and comfort drive with a spindle drive

Abstract

A spindle drive (10) comprising a drive motor (12) connected to a multi-part gear housing (15), wherein the gear housing (15) has a housing base body (17) in which a receiving space (20) is formed for a drive element (25) arranged in operative connection with a spindle (26), wherein the drive element (25) is drivable by the drive motor (12), wherein the receiving space (20) is closed at least on one end face by a cover element (30, 30), and wherein spring means are provided which apply an axial force acting in the direction of the longitudinal axis (28) of the spindle (26) to the drive element (25) within the receiving space (20), so that the drive element (25) is arranged in the receiving space (20) without axial play, and wherein the spring means are arranged at least indirectly in contact with the at least one cover element (30, 35), characterized in thatthat the spring means are formed by the housing base body (17) which is at least partially elastic and which is elastically deformable by the at least one cover element (30, 35) in the direction of the longitudinal axis (28) of the spindle (26), so that the at least one cover element (30, 35) acts at least indirectly on the drive element (25).

Description

State of the art

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

[0002] From DE 10 2016 205 639 A1, the applicant discloses a spindle drive with the features of the preamble of claim 1. The known spindle drive is characterized by a gear housing in which a drive element in the form of a worm gear is arranged, connected to a spindle. The external toothing of the worm gear or drive element is operatively connected to an output element of the drive motor to rotate the spindle about its longitudinal or rotational axis.

[0003] Such a spindle drive serves in particular as a component of a comfort drive in a motor vehicle for the (longitudinal) adjustment of a seat, for which purpose the spindle is movable in both directions of rotation. In order to minimize or completely avoid axial play between the drive element and the receiving space for the drive element in the transmission housing due to component tolerances, particularly when the direction of rotation of the drive motor or spindle is reversed for noise reasons, the known spindle drive provides that the drive element is arranged within the receiving space of the transmission housing so that it is axially loaded in one direction of the receiving space by a spring element in the form of a wave spring.This spring means represents an additional component that enlarges the installation space of the receiving space of the gear housing, which also requires additional assembly work when installing the spindle drive. Disclosure of the invention

[0004] The spindle drive according to the invention with the features of claim 1 has the advantage that the axial force acting on the drive element in the direction of the rotational or longitudinal axis of the spindle can be applied without an additional component in the form of a wave spring or the like, in accordance with the prior art. This particularly simplifies the assembly of the spindle drive. Furthermore, the installation space required for accommodating the drive wheel in the gear housing is minimized. To this end, the invention according to the teaching of claim 1 proposes that the spring means be formed by a housing base body of the gear housing that is elastically designed at least in some regions and is elastically deformable in the direction of the longitudinal axis of the spindle by a cover element, so that the cover element acts at least indirectly with the axial force on the drive element.

[0005] In other words, this means that the housing base body of the gear housing is elastically deformed in some areas by the cover element and is thereby shortened in the (longitudinal) direction of the spindle or towards the drive element, so that the cover element is arranged at least indirectly in contact with the drive wheel and thereby exerts the desired axial force for the axial play-free arrangement of the drive element in the gear housing.

[0006] Advantageous further developments of the spindle drive according to the invention are specified in the subclaims.

[0007] The housing base also has areas or sections that should not or do not need to be deformed, since no axial preload force can or needs to be exerted on the drive wheel via these areas or sections. This could, for example, be a connecting flange or connecting area of the housing base, via which the housing base is connected to the drive motor. Therefore, in a preferred embodiment of the invention, the housing base has at least two areas made of materials with different moduli of elasticity (elasticity), and the cover element is arranged in contact with the area having a lower modulus of elasticity. This makes it possible, in particular, to form the connecting flange area of the housing base from the harder material.

[0008] It is particularly preferred if the housing base body is designed as a monolithic 2-component injection-molded part. This eliminates the need for the two regions or sections of the housing base body, which have different hardness or a different modulus of elasticity, to be formed from separate components that would then have to be joined together by an additional joining process. Such a design would result in additional, undesirable assembly effort. The preferred design as a 2-component injection-molded part, on the other hand, makes use of the known manufacturing possibilities of 2-K injection molding, since the housing base body is usually designed as an injection-molded part and the additional, elastically deformable region can thus be monolithically injection-molded onto the non-deformable or less deformable region, or vice versa.

[0009] In order to achieve the desired deformation properties of the housing base body, in particular taking into account the smallest possible volume fraction of the elastically deformable region in the entire housing base body, it is provided that the region having a lower modulus of elasticity is formed from an elastomer.

[0010] As already explained above, the housing base body typically has different functional areas with corresponding requirements for the functional areas. In particular, the housing base body is provided with a connecting flange for connecting to the drive motor and a receiving area with the receiving space, wherein the elastically deformable area is arranged exclusively in the receiving area.

[0011] In a further development of the last proposal, it is provided that the elastically deformable region is annular or flat and is arranged between a central region of the receiving region and in contact with the cover element.

[0012] A further optimization of the spindle drive, in which axial forces can be introduced onto the drive element via both end faces of the drive element, provides that the receiving area of the housing base body is closed on opposite sides by a cover element each, and that two elastically deformable areas are provided, each of which interacts with the cover element facing it.

[0013] To apply the deformation forces to the housing base body, it is particularly preferred that the at least one cover element be connected to the housing base body by means of screw connections. The fastening screws typically engage the area of the housing base body with a higher modulus of elasticity, thereby compressing the elastic area.

[0014] The invention also includes a comfort drive, in particular a seat adjustment drive with a spindle drive according to the invention as described so far.

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

[0016] This shows in: Fig. 1 a perspective view of a partially assembled spindle drive according to the invention, Fig. 2 a side view of a part of the gear housing of the spindle drive of the Fig. 1 and Fig. 3 and Fig. 4 in a schematic representation of the operating principle of the gear housing designed according to the invention in the unassembled and assembled state.

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

[0018] In the Fig. 1 shows a spindle drive 10 as it serves as a component of a comfort drive 100 for the (longitudinal) adjustment of a seat (not shown) in a motor vehicle. The spindle drive 10 has a drive motor 12 designed as an electric motor, which is connected to a multi-part gear housing 15 by means of fastening screws 14. The gear housing 15 has a housing base body 17 with a connecting flange 16, in the area of which the connection to the drive motor 12 is made. In the exemplary embodiment, in one piece, i.e. monolithic with the connecting flange 16, the housing base body 17 has a receiving area 18 which has a transverse bore for forming a receiving space 20. The receiving space 20 is arranged laterally offset from a dome section 22 which serves to receive an output shaft of the drive motor 12 and an output element (not shown) connected to the output shaft.This output element of the drive motor 12 interacts in a manner known per se with a toothing 24 of a drive element 25 designed as a worm wheel, which is accommodated within the receiving space 20 of the receiving area 18.

[0019] The drive element 25 is arranged in operative connection with a spindle 26, which is rotatable together with the drive element 25 about its common longitudinal or rotational axis 28 by means of the drive motor 12 in order to adjust the element to be adjusted (seat) at least indirectly in a manner known per se during the rotation.

[0020] The receiving space 20 within the receiving area 18 is designed in the form of a through-bore. The receiving space 20 is closed on its two opposite ends by a housing cover 30 secured by fastening screws 32, and by a vehicle-specific or customer-specific interface cover 35, also secured by fastening screws 36. The interface cover 35 has, for example, a through-bore 38 through which the spindle drive 10 can be secured to a vehicle body.

[0021] For mounting the drive element 25 in the receiving space 20, the two opposite end faces of the drive element 25 are - in a manner also known per se - arranged in operative connection with a bearing element in the form of a bearing ring 40, 42, which are also located within the receiving space 20.

[0022] In order to prevent an axial movement of the drive element 25 in the direction of the housing cover 30 or the interface cover 35, which would otherwise be associated with noise, particularly when the direction of rotation of the drive motor 12 is reversed and thus when a force acts on the drive element 25 in a different direction than the rotational axis 28 of the spindle 26, the drive element 25 is arranged within the receiving space 20 without axial play. This is achieved by applying at least one axial force acting in the direction of the rotational axis 28 to the drive element 25.

[0023] For this purpose, the invention provides that according to the representation of the Fig. 2 to 4, the receiving region 18 of the housing base body 17 has, in the region of the end face facing the housing cover 30 or the interface cover 35, a region 44, 45 which consists of a material which has a lower modulus of elasticity than a (central) region 46 of the receiving region 18 which is located between the two regions 44, 45. In the exemplary embodiment shown, the two annular regions 44, 45, which are preferably made of an elastomer, each have flat end faces 48, 49, the thickness d of the regions 44, 45 being, for example, between approximately 10% and 30% of the thickness D of the receiving region 18. In particular, the two regions 44, 45 are monolithically bonded to the region 46 ormolded onto the receiving area 18 of the housing base body 17, in that the housing base body 17 is formed as a two-component injection-molded part 50, in which the areas 44, 45 are formed on the (central) area 46 during the injection molding process when the housing base body 17 is formed. The central area 46 consists, for example, of polyamide (PA), in particular of PA66.

[0024] In the Fig. 3, the receiving area 18 with the receiving space 20 is shown in a state in which the housing cover 30 and the interface cover 35 are not yet connected to the receiving area 18 or are not (axially) clamped by means of the fastening screws 32, 36. In particular, it can be seen that the assembly 52 consisting of the drive element 25 and the two bearing rings 40, 42 has an axial longitudinal extent I that is (slightly) less than the longitudinal extent L of the receiving area 18 or the receiving space 20. The bearing rings 40, 42 extend into the area of the two elastically deformable areas 40, 45 of the receiving area 18.

[0025] In the Fig.4 shows the state with the housing cover 30 and interface cover 35 mounted. The axial clamping forces acting on the receiving area 18 via the fastening screws 32 and 36 (not shown) elastically compress the areas 44, 45, so that the bearing rings 40, 42 are arranged in end-to-end contact with the housing cover 30 and the interface cover 35, respectively, so that the drive element 25 is arranged within the receiving space 20 without axial play.

[0026] The spindle drive 10 described so far can be modified or altered in many different ways without deviating from the inventive concept.

Claims

[1] Spindle drive (10) comprising a drive motor (12) connected to a multi-part gear housing (15), wherein the gear housing (15) has a housing base body (17) in which a receiving space (20) is formed for a drive element (25) arranged in operative connection with a spindle (26), wherein the drive element (25) is drivable by the drive motor (12), wherein the receiving space (20) is closed at least on one end face by a cover element (30, 30), and wherein spring means are provided which apply an axial force acting in the direction of the longitudinal axis (28) of the spindle (26) to the drive element (25) within the receiving space (20), so that the drive element (25) is arranged in the receiving space (20) without axial play, and wherein the spring means are arranged at least indirectly in contact with the at least one cover element (30, 35), characterized bythat the spring means are formed by the housing base body (17) which is at least partially elastic and which is elastically deformable by the at least one cover element (30, 35) in the direction of the longitudinal axis (28) of the spindle (26), so that the at least one cover element (30, 35) acts at least indirectly on the drive element (25). [2] Spindle drive according to claim 1, characterized by that the housing base body (17) has at least two regions (44, 45, 46) which are formed from materials with a different modulus of elasticity, and that the at least one cover element (30, 35) is arranged in abutting contact with the region (46) having a lower modulus of elasticity. [3] Spindle drive according to claim 1 or 2, characterized by that the housing base body (17) is designed as a monolithic 2-component injection-molded part. [4] Spindle drive according to claim 2 or 3, characterized bythat the region (44, 45) having a lower modulus of elasticity is formed from an elastomer. [5] Spindle drive according to one of claims 2 to 4, characterized by that the housing base body (17) has a connecting flange (16) for connection to the drive motor (12) and a receiving area (18) with the receiving space (20), and that the elastically deformable area (44, 45) is arranged exclusively in the receiving area (18). [6] Spindle drive according to claim 5, characterized by that the elastically deformable region (44, 45) is annular and is arranged between the region (46) of the receiving region (18) having the lower modulus of elasticity and in contact with the at least one cover element (30, 35). [7] Spindle drive according to claim 5 or 6, characterized bythat the receiving area (18) is closed on opposite sides by a cover element (30, 35) in each case, and that two elastically deformable areas (44, 45) are provided, which each interact with a cover element (30, 35). [8] Spindle drive according to one of claims 1 to 7, characterized by that the at least one cover element (30, 35) is connected to the housing base body (17) by means of fastening screws (32, 36). [9] Spindle drive according to one of claims 2 to 8, characterized by that the drive element (25) and any bearing elements (40, 42) adjoining it in the longitudinal direction of the spindle (26) have / have a first longitudinal extension (I) in the receiving space (20) which is less than a second longitudinal extension (L) of the receiving space (20) in the state not connected to the cover element (30, 35), wherein the first longitudinal extension (I) extends into the elastically deformable regions (44, 45). [10] Comfort drive (100), in particular seat adjustment drive, with a spindle drive (10) which is designed according to one of claims 1 to 9.

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