Gearbox housing and gearbox drive unit

Abstract

Gearbox housing (10), in particular for a seat adjustment drive (8) in a motor vehicle, comprising a housing base body (12) having a peripheral wall (15) and a housing cover (11), as well as a locking mechanism (20) for fixing the housing cover (11) to the housing base body (12), wherein locking elements (22) are arranged on the radial inner side (16) of the peripheral wall (15) and can be locked with counter-locking elements (24) on a radial outer wall (14) of the housing cover (11), wherein the housing cover (11) has an outer axial cover surface (13) which, when installed in the motor vehicle, is flush with an axial end face (18) of the peripheral wall (15) and does not project axially beyond it, wherein recesses (44) for the locking elements (22) are formed in the radial outer side (17) of the housing cover (11) axially adjacent to the counter-locking elements (24),which extend in the axial direction (30) at least by an axial spring travel (50) of the transmission components (52) installed in the transmission housing (10).

Description

State of the art

[0001] The invention relates to a transmission housing and a transmission drive unit comprising the same, in particular for seat adjustment drives in motor vehicles, according to the preamble of the independent claims.

[0002] Common gear housings for vehicle seat adjustment systems consist of a tub-like housing base and a housing cover. A variety of solutions exist for attaching the housing cover to the housing base. For example, it is common practice to attach the housing cover to the housing base using screws and / or snap hooks.

[0003] DE10 2007 044 351 A1 discloses a gearbox housing in which the housing cover is secured to the housing base exclusively by means of snap hooks. The snap hooks arranged on the housing base project beyond its peripheral wall in the axial direction. Spring tabs are formed circumferentially on the housing cover, projecting radially outward beyond the peripheral wall. Although this solution allows for the elimination of additional screw connections, this snap connection requires additional radial and axial space.

[0004] DE 10 2013 208 217 A1 shows a gearbox housing in which the radial outer wall of the housing cover is inserted within the peripheral wall of the housing base body. An annular projection of the housing base body engages the corresponding groove of the housing cover in a form-fitting manner. Disclosure of the invention

[0005] The invention is therefore based on the object of proposing a space-optimized, easy-to-manufacture and easy-to-assemble gearbox housing. This object is achieved by the features of the independent claims. Advantageous developments of the invention are specified in the subclaims. The scope of the invention also includes all combinations of at least two of the features specified in the description, the claims, and / or the figures. Advantages of the invention

[0006] The gear housing according to the invention and the drive unit comprising it with the features of the independent claims have the advantage that the arrangement of the locking and counter-locking elements within the gear housing reduces the axial height by approximately the thickness of the axial cover wall. Likewise, the radial expansion at the peripheral wall is reduced, since the entire locking connection is arranged radially within the peripheral wall. This allows the required installation space at the customer interface to the mounting flange to be reduced. No additional connecting elements or assembly steps are required to close the gear housing.

[0007] The measures listed in the dependent claims enable advantageous further developments and improvements of the designs specified in the independent claims. Because the outer diameter of the gear cover is smaller than the inner diameter of the peripheral wall (apart from the locking and counter-locking elements), the housing cover can be completely accommodated within the housing base body, whereby the housing cover does not protrude radially beyond the peripheral wall.

[0008] For transporting the gear drive unit, the housing cover protrudes axially beyond the peripheral wall. However, if the drive unit is attached to a mounting flange, the cover surface is pressed axially in until it is flush with the peripheral wall. This limits the axial installation space to the axial extent of the peripheral wall of the housing base body.

[0009] By molding the locking elements axially spaced from the end faces of the peripheral wall and the housing cover, the locking connection is located entirely within the housing and is not visible from the outside. Such a hidden locking connection can therefore also be designed to be non-destructive and permanently removable.

[0010] In terms of manufacturing technology, the locking elements can be manufactured as locking lugs and counter-locking lugs in one piece with the base body and the housing cover – particularly using plastic injection molding. The simple geometry of the locking lugs also allows the injection mold to be manufactured very easily and cost-effectively. By selecting the material thickness of the housing cover and the peripheral wall, the elasticity in the radial direction of the locking and counter-locking elements can be adjusted accordingly.

[0011] In a preferred embodiment, the locking elements and counter-locking elements extend over a circular segment that covers at least 30°. For example, two radially opposing locking elements and counter-locking elements are arranged, extending approximately 80° to 100° over an angular range. Due to the large circumferential extent, the locking lugs can be designed with a very small overlap in the radial direction, which significantly reduces the assembly force of the cover.

[0012] The elastic design of the radial outer wall of the cover or the peripheral wall is adapted to the radial overlap of the locking surfaces between the locking lugs and the counter-locking lugs so that the gear housing has sufficient stability.

[0013] Optionally, axially open radial openings can be formed in the radial outer wall of the housing cover, which increases the radial mobility of the radial outer wall.

[0014] If recesses extending axially are formed in the radial outer wall or in the peripheral wall according to the invention, the locking elements or counter-locking elements can be axially displaced relative to one another after they have been locked. This allows the locking connection to be used as a transport lock for the gear drive unit, and when the drive is flange-mounted to a mounting flange, the housing cover can be axially engaged into the peripheral wall without the locking connection having to be released again.

[0015] A spring element is located inside the gearbox housing, which holds the housing cover under preload. This presses the locking surfaces of the locking elements and counter-locking elements against each other, reducing the forces acting on the housing cover during transport. When the drive unit is attached to a mounting flange, the housing cover is then pressed axially into the peripheral wall against this spring force until the axial outer surface of the cover is flush with the end face of the peripheral wall on the mounting flange.

[0016] If the locking surfaces of the locking and counter-locking elements are approximately perpendicular to the axial direction, the locking connection can be designed as a non-detachable connection. However, if the locking surfaces are inclined relative to the axial direction, the locking connection can be released again by applying the necessary tensile force to the cover.

[0017] The gearbox can advantageously be designed as a worm gear, in which a worm is arranged on the armature shaft of the electric motor, which meshes with a corresponding worm gear mounted in the gearbox housing. To reduce the rotation of the worm gear, an eccentric or planetary gear can also be arranged in the gearbox housing. An output element is arranged on one gearbox component and protrudes through a central opening in the housing cover. In this way, a very compact drive unit with a high reduction ratio can be realized, with the individual gearbox components being axially mounted in the housing base body by the fixation of the housing cover.

[0018] The gearbox has, for example, a rotationally fixed slide, in which an eccentric wheel is preferably guided. The slide is mounted in radial recesses in the peripheral wall. The housing cover has corresponding radial extensions which, once mounted on the housing base, close these recesses in the peripheral wall. Thus, the partial ring snap connection according to the invention can also be used for cover elements that are not completely circular, but only over certain angular ranges. To apply the axial spring force, which presses the housing cover from the inside to the outside, the axially acting spring element is arranged within the gearbox housing. The spring element can be designed particularly simply as a closed ring that completely encloses the axis of the worm wheel.For example, such a spring element can be inserted axially between the bottom of the housing base body and the worm gear, so that the axial spring force clamps all gear components from the inside against the housing cover.

[0019] The material savings make the drive unit lighter. No axial assembly tolerances need to be considered, as the gear components are automatically positioned axially precisely during installation on the mounting flange. A particularly advantageous design of the gear housing is one in which, apart from the locking mechanisms and any centering projections, no additional fastening elements such as screws, etc., are required to secure the housing cover to the housing base, which is particularly tub-shaped. Drawings

[0020] The embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

[0021] They show: Fig. 1 a gear drive unit according to the invention before installation Fig. 2 an unsealed housing base body according to the invention Fig. 3 a transmission according to the invention with housing cover, and Fig. 4 a and b a section of a gearbox according to the invention before and after installation in the motor vehicle Description of the embodiments

[0022] In Fig. 1, a seat adjustment drive is shown as a gear drive unit 8, which is attached, for example, to a side bolster 61 of a seat frame. This frame surface of the seat forms a mounting flange 60 for the gear drive unit 8. An electric motor 54 drives a worm 69 via an armature shaft, which in turn drives a worm gear 68 mounted in a gear housing 10. This worm gear 64 transmits the drive torque via a driver to the output pinion 70, which extends through a recess in the mounting flange 60 and is operatively connected to a seat component to be adjusted (e.g., seat surface or seat back) - for example, via a corresponding ring gear and / or a flex shaft. A housing cover 11 is pre-fixed in a housing base body 12 via a partial ring snap connection 20 and is only moved into its final axial position upon attachment to the mounting flange 60.The gear drive unit 8 is screwed to the mounting flange 60, for example, using screws as connecting elements 58. For this purpose, the connecting elements 58 are inserted through holes 59 in the mounting flange 60 and secured in mounting bosses 56, in particular by means of self-tapping screws screwed into the plastic of the gear housing 10. In . Fig. 1, the mounting flange 60 is shown in dashed lines before the transmission drive unit 8 has been bolted thereto, with the mounting flange being spaced from an outer cover surface 13 of the housing cover 11 by a spring travel 50. After installation, both an end face 18 of a peripheral wall 15 of the housing base body 12 and the outer cover surface 13 axially bear against the mounting flange 60. The housing cover 11 is pressed axially against the mounting flange 60 by a spring element 51, which is arranged between a bottom surface 49 of the housing base body 12 and the transmission components 52 - in particular the worm gear 68 - within the transmission housing 10. This displaces the transmission components 52 to their correct axial operating position during installation in the motor vehicle. The fastening domes 56 are formed integrally with the housing base body 12, preferably by injection molding.

[0023] In Fig. 2 only shows the empty housing base body 12, on whose bottom surface 49 the axial spring element 51 is inserted. In the center, along an axis 66, a shaft 67 is arranged which is fixed to the housing and on which the gear components 52 are mounted. On an inner side 15 of the peripheral wall 15 of the housing base body 12, locking lugs 23 are formed as locking elements 22, which extend in the circumferential direction over a certain angular range 32. For example, two partially annular locking elements 22 can be formed, each extending over approximately 90° over the approximately circular inner circumference of the peripheral wall 15. In this embodiment, the peripheral wall 15 is, to a first approximation, rigid, so that the housing cover 11 is designed to be correspondingly radially flexible for locking within the peripheral wall 15.

[0024] Fig. Figure 3 shows the gear unit, which is mounted in the gear housing 10, together with the housing cover 11. The worm gear 68 has an invisible eccentric, which causes an eccentric gear 78 to move eccentrically. To ensure that a ring gear 79, which is firmly connected to the output pinion 70, rolls on the eccentric gear 78, the eccentric gear 78 is guided by a slider 76, which is non-rotatably mounted in the housing base body 12. For this purpose, radial recesses 80 are formed in the housing base body 12, in which the slider 76 engages radially. The ring gear 79 is covered by the housing cover 11, with an axial extension with the pinion 70 having a cylindrical collar 71, against which the edge of a hole 72 in the housing cover 11 rests. The housing cover 11 here has radial extensions 82 which cover the corresponding radial recesses 80 in the housing base body 12.Below the worm gear 68 is the spring ring 51, which, after assembly of the gearbox, axially clamps the gearbox components 52 between the base surface 49 and the inside of the housing cover 11. The spring element 51 is designed, for example, as a corrugated ring that encloses the shaft 67. The spring force is very low or zero when the gearbox drive unit 10 is in the transport position and is only increased upon attachment to the mounting flange 60 by axially pressing in the housing cover 11, so that the gearbox components 52 are axially precisely positioned by the axial spring force. Counter-locking elements 24 are formed on the housing cover 11, which form a locking connection 20 with the locking elements 22 when the housing cover 11 is inserted into the housing base body 12.The counter-locking elements (24) are also designed as radial counter-locking lugs 25, which extend over the angular range 23 in the circumferential direction, for example also over 2 x approximately 90°. On the outer circumference of the housing cover 11, an axial slot 36 is formed here, which allows a certain radial flexibility of the outer wall 14 with its counter-locking lugs 25. In this embodiment, an axial pin 37 formed on the housing base body 12 engages in the slot 36.

[0025] A section through the gearbox housing 10 is shown in Fig. 4a before installation and in Fig. 4b after installation. The locking lugs 23 and counter-locking lugs 25 each have insertion phases 26, 28 so that the locking and counter-locking elements 22, 24 slide smoothly into their locking position upon axial insertion of the housing cover 11. A recess 44 is formed on the housing cover 11 axially adjacent to the counter-locking lug 25, in which the locking lug 23 can be axially displaced, in particular without jamming. In this state according to Fig. 4a, the housing cover 11 is secured against loss during transport. The housing cover 11 is pressed axially outward by the spring element 51 (not shown here), so that locking surfaces 84 formed on the locking and counter-locking elements 22, 24 abut one another. Due to the radial alignment of the abutting locking surfaces 84 of the locking and counter-locking elements 22, 24, the locking connection 20 is designed to be non-detachable and represents reliable protection against loss. Alternatively, inclined locking surfaces 85 can be designed obliquely to the axial direction 30, so that the locking connection 20 can also be designed to be detachable. When installing the gear drive unit 8 according to Fig.4b, the housing cover 11 is pressed into the housing base body 12 by the amount of spring travel 50, so that the housing cover 11 no longer protrudes from the housing base body 12, but rests axially against the mounting flange 60. As a result, the outer cover surface 13 of the housing cover 11 is flush with the end face 18 of the peripheral wall 15. The locking lugs 22 are guided axially within the recesses 44. The locking surfaces 84 then no longer abut one another in the operating state, so that the locking connection 20 can be designed for minimal loading only during transport (loss protection).

[0026] It should be noted that, with regard to the exemplary embodiments shown in the figures and in the description, a wide variety of combinations of the individual features are possible. For example, the specific design of the locking and counter-locking elements 22, 24, as well as their number and angular ranges, can be varied. The type of locking connection 20 is designed as a partial ring snap connection, although the locking elements can also be designed flexibly or the recesses can be formed on the peripheral wall. Instead of the eccentric or planetary gear, other gear designs can also be arranged in the gear housing in order to transmit the drive torque of the electric motor to the part to be adjusted via the output element 70.The invention is particularly suitable for adjusting movable parts in motor vehicles, in particular for adjusting seat components, wherein the gear drive unit is preferably flanged to a side part of the vehicle seat.

Claims

[1] Gearbox housing (10), in particular for a seat adjustment drive (8) in a motor vehicle, with a housing base body (12) having a peripheral wall (15) and a housing cover (11), as well as with a locking mechanism (20) for fixing the housing cover (11) to the housing base body (12), wherein locking elements (22) are arranged on the radial inner side (16) of the peripheral wall (15) and can be locked with counter-locking elements (24) on a radial outer wall (14) of the housing cover (11), wherein the housing cover (11) has an outer axial cover surface (13) which, when installed in the motor vehicle, is flush with an axial end face (18) of the peripheral wall (15) and does not project axially beyond it, wherein recesses (44) for the locking elements (22) are formed in the radial outer side (17) of the housing cover (11) axially adjacent to the counter-locking elements (24),which extend in the axial direction (30) at least by an axial spring travel (50) of the transmission components (52) installed in the transmission housing (10). [2] Gearbox housing (10) according to claim 1, characterized by that the housing cover (11) can be inserted completely axially within the peripheral wall (15) of the housing base body (12) along an axial mounting direction (30). [3] Gearbox housing (10) according to one of claims 1 or 2, characterized by that in the recesses (44) locking lugs (23) of the locking elements (22) are axially displaceable without jamming, wherein locking surfaces (84) of the locking elements (22) and the counter-locking elements (24) do not axially abut one another in the operating state. [4] Gearbox housing (10) according to one of the preceding claims, characterized bythat the locking elements (22) are formed axially spaced from the axial end face (18) on the inner side (16) of the peripheral wall (15), and the counter-locking elements (24) are formed on a radial outer side (17) of the radial outer wall (14) of the housing cover (11) axially spaced from the axially outer cover surface (13). [5] Gearbox housing (10) according to one of the preceding claims, characterized by that the locking elements (22) are formed integrally with the peripheral wall (15) as the radial locking lugs (23) and the counter-locking elements (24) are formed integrally with the housing cover (11) as radial counter-locking lugs (25), which each have insertion phases (26, 28) which slide axially past one another during locking. [6] Gearbox housing (10) according to one of the preceding claims, characterized bythat the locking elements (22) and the counter-locking elements (24) are partially annular, wherein they extend in particular over an angular range (32) which is greater than 30° and preferably approximately 70° - 100°. [7] Gearbox housing (10) according to one of the preceding claims, characterized by that the housing cover (11) is designed to be radially flexible in such a way that its radial outer wall (14) can be elastically deformed radially inwards at least by the amount (34) of the radial overlap of the locking lugs (23) with the counter-locking lugs (25) when inserted into the housing base body (12). [8] Gearbox housing (10) according to one of the preceding claims, characterized by that the radial outer wall (14) has axially open slots (36). [9] Gear drive unit (8) with a gear housing (10) according to one of the preceding claims, wherein the gear housing (10) accommodates gear components (52) which are driven by an electric motor (54), characterized by that the gear components (52) are braced against the housing cover (11) by means of an axially acting spring element (51) - wherein, in particular in the non-installed state of the gear drive unit (8), the outer axial cover surface (13) projects beyond the axial end face (18) of the peripheral wall (15). [10] Gear drive unit (8) according to claim 9, characterized bythat screw-on domes (56) are formed on the housing base body (12) which, when the transmission drive unit (8) is installed, receive connecting elements (58) which press the end face (18) against a mounting flange (60) - preferably a frame surface (61) of the vehicle seat - and the housing cover (11) against the spring force of the spring element (51) into the housing base body (12), wherein in particular the outer axial cover surface (13) also rests axially resiliently against the mounting flange (60). [11] Gear drive unit (8) according to one of claims 9 or 10, characterized by that the gear components (52) form a worm gear (64) in which a worm wheel (68) mounted on an axle (66) fixed to the housing meshes with a worm (69) driven by the electric motor (54), and an output pinion (70) which is operatively connected to the worm wheel (68) projects outwards from a hole (72) in the housing cover (11). [12] Gear drive unit (8) according to one of claims 9 to 11, characterized by that the gear components (52) form a planetary gear (74) in which a slide (76) for guiding an eccentric gear (78) is mounted in a rotationally fixed manner in radial recesses (80) of the housing base body (12) - wherein in particular the housing cover (11) has radial extensions (82) which tightly close the radial recesses (80) in the axial direction (30). [13] Gear drive unit (8) according to one of claims 9 to 12, characterized by that the spring element (51) is annular and is arranged axially between the bottom (49) of the housing base body (12) and the worm wheel (68) - and in particular the spring element (51) completely encloses the axis (66) of the worm wheel (68).

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