Adjustment drive and method for manufacturing an adjustment drive

Abstract

Adjustment drive, in particular for a steering column adjustment or a vehicle seat of a motor vehicle, with - a housing (2), - an output shaft (4) rotatably mounted in the housing (2) and - a wedge-shaped compensating element (5) to prevent axial play of the output shaft (4), wherein the compensating element (5) is supported in its operating position on the housing (2) and an axial stop of the output shaft (4), characterized in that the compensating element (5) is connected to the housing (2) by ultrasonic welding to ensure the axially play-free arrangement of the output shaft (4) in its operating position and the compensating element (5) protrudes from a housing opening (7) with a radially projecting projection (6) towards the output shaft (4).

Description

[0001] The invention relates to an adjustment drive, in particular for a steering column adjustment or a vehicle seat of a motor vehicle, with - a housing, - an output shaft rotatably mounted in the housing and - a wedge-shaped compensating element for avoiding axial play of the output shaft, wherein the compensating element is supported in its operating position on the housing and an axial stop of the output shaft, as well as a method for producing such an adjustment drive.

[0002] Adjustment drives of the type mentioned above are used in a wide variety of designs in motor vehicles for the motorized adjustment of various vehicle components, enabling, for example, the adaptation of vehicle controls, seat positions, etc., to the individual occupants. Adjustment drives of the type mentioned above are used, among other things, in vehicle seats for adjusting various seat components and also for adjusting the position of the steering column to suit the individual driver.

[0003] In order to provide a convenient and reliable adjustment option and also to avoid unpleasant clicking noises in the event of a reversal of the direction of rotation of the output shaft, it is necessary to compensate for the axial play of the output shaft so that it engages with the vehicle component to be adjusted with essentially no play.

[0004] DE 198 54 535 A1 discloses a generic adjustment drive for a windshield wiper system of a motor vehicle. The axial play of the output shaft is compensated for by a wedge slide, which presses radially against an axial stop on the armature shaft and thereby axially displaces the output shaft. The necessary displacement force acting on the wedge slide is applied by a spring element, which presses the wedge slide toward the output shaft. However, due to high continuous loading of the spring element, the elastic properties deteriorate over its entire service life, which means that the axial play is no longer reliably compensated, allowing the output shaft to move back and forth, particularly under load.

[0005] For example, DE 10 2006 049 808 A1 discloses a further adjustment device for adjusting an adjustment part in a motor vehicle, in particular a seat part.

[0006] The invention is based on the object of providing an adjustment drive and a method for producing an adjustment drive of the type mentioned at the outset, in which axial play of the output shaft is compensated reliably and permanently.

[0007] The invention solves the problem by an adjustment drive having the features of claim 1 and a method having the features of claim 12. Advantageous developments of the inventions are specified in the dependent claims.

[0008] A characteristic feature of the adjustment drive according to the invention is that the compensating element is connected to the housing by ultrasonic welding to ensure that the output shaft is positioned free of axial play in its operating position. Within the scope of the invention, the operating position refers to the position of the compensating element in which it secures the output shaft to the housing in an axial play-free arrangement, thus reliably preventing backlash in the adjustment of the vehicle components adjusted by the adjustment drive or unpleasant noise pollution during operation of the adjustment drive.

[0009] According to the invention, the compensating element is displaced into a position relative to the output shaft in which the compensating element rests on the housing on the one hand and on an axial stop of the output shaft on the other, such that the output shaft no longer exhibits any axial play. To secure this operating position of the compensating element, it is connected to the housing in this position relative to the housing by ultrasonic welding. For this purpose, the housing and the compensating element are formed from a plastic, at least in the area of ​​the ultrasonic weld connection; both the housing and the compensating element can be made entirely of a plastic.

[0010] The ultrasonic welding process is characterized by its reliable, inseparable connection between the housing and the compensating element, resulting in a permanent fixation of the compensating element to the housing and thus to the output shaft. Furthermore, ultrasonic welding is simple and cost-effective, with high welding speeds and excellent efficiency. The thermoplastic material of the compensating element and the housing are melted in the contact area and joined during the solidification process, ensuring a secure arrangement of the compensating element in the operating position.

[0011] Overall, the adjustment drive according to the invention thus has an output shaft arranged free of axial play over the entire service life, wherein in particular the connection of the compensation element to the housing produced by means of ultrasonic welding, by which the operating position is permanently fixed, reliably ensures that the play-free arrangement is also maintained over the entire service life of the adjustment drive.

[0012] To compensate for axial play, the compensating element rests in its operating position on the housing on one side and on an axial stop on the output shaft on the other, thus ensuring the play-free arrangement of the output shaft. The compensating element can interact with an axial stop on the output shaft at any location. The axial stop can be formed, for example, by a shaft end, with the compensating element then being arranged between the shaft end and the housing.

[0013] According to a particularly advantageous embodiment of the invention, however, the compensating element has a U-shaped receiving opening that surrounds the output shaft in the region of a shaft shoulder forming an axial stop. According to this embodiment of the invention, a shaft shoulder, which can be formed in any desired shape, e.g. by a pinion arranged on the shaft with a surface extending radially from the output shaft and running essentially perpendicular to the shaft axis, forms an axial stop against which the compensating element rests in its operating position. In order to enable a particularly good arrangement of the compensating element relative to the output shaft, the compensating element has a U-shaped receiving opening whose opening cross-section is adapted to the diameter of the output shaft in the region of the compensating element mounted in the operating position.

[0014] A corresponding development of the invention particularly ensures a positionally stable arrangement of the compensating element relative to the output shaft in the selected operating position, but also in a pre-assembled position, in which the compensating element still has to be moved radially toward the balance shaft into the operating position to achieve an axially play-free arrangement of the output shaft. Furthermore, the U-shaped receiving opening enables secure installation of the compensating element on the output shaft and reduces loads acting on the compensating element during operation.

[0015] The compensation element can, in principle, be supported on the housing at any location. For example, it is conceivable to design the compensation element such that the compensation element is supported on a suitable housing area with a section radially displaced relative to the axial stop. According to a particularly advantageous embodiment of the invention, however, in the operating position, the compensation element rests against a contact surface of the housing with a support surface facing away from the axial stop. According to this embodiment of the invention, the compensation element extends in a region between two opposing surfaces, namely the housing and the axial stop.A support surface of the compensating element rests against a contact surface of the housing, and the axial stop of the output shaft rests against a stop surface of the compensating element, thus ensuring particularly reliable axially free support of the output shaft in the operating position of the compensating element. In the operating position, the compensating element displaces the output shaft over the axial stop into a position free of axial play, with the compensating element resting against the housing with its support surface on the side opposite the axial stop.

[0016] The wedge-shaped design of the compensating element is essential for its function. Depending on the radial position of the compensating element relative to the output shaft, the distance between the housing and an axial stop can be adjusted via the compensating element. In principle, the use of a wedge-shaped compensating element is sufficient to ensure its function in the adjustment drive according to the invention. However, due to the wedge-shaped design, a linear connection may be partially present between the compensating element and the axial stop and / or the associated contact surface in the housing.

[0017] According to an advantageous development of the invention, the contact surface is inclined in the opposite direction to a plane running vertically to the output shaft, corresponding to the wedge shape of the compensating element. According to this embodiment of the invention, the contact surface of the housing, which interacts with the compensating element in the operating position, is inclined corresponding to the wedge angle of the compensating element, with the profile being such that the surface tapers in the direction of insertion of the compensating element. This results in the compensating element in the operating position on the output shaft being in flat contact with both the axial stop and the contact surface of the housing. This ensures a particularly reliable arrangement free of axial play, which remains intact over the entire service life of the adjustment drive.

[0018] The design of the contact surface with a shape inclined corresponding to the compensating element can, in principle, be implemented in any desired manner. For example, an attachment can be arranged on the housing in the area of ​​the contact surface, which is connected to the housing wall. According to a particularly advantageous embodiment of the invention, however, the contact surface is formed integrally with the housing. This allows the adjustment drive in a correspondingly developed form to be manufactured particularly easily and cost-effectively, since additional assembly effort for providing a correspondingly inclined contact surface is eliminated.

[0019] The arrangement of the compensating element relative to the output shaft, i.e., in particular, the radial adjustment of the compensating element during pre-assembly toward the output shaft into the operating position, in which the compensating element supports the output shaft in a play-free position, can in principle be carried out in any desired manner. According to a particularly advantageous embodiment of the invention, however, the compensating element protrudes from a housing opening with an actuating portion, in particular with a projection protruding radially relative to the output shaft.

[0020] According to this embodiment of the invention, according to which the actuating section preferably has a smaller cross-section than the rest of the compensating element, the adjusting drive with the compensating element can be easily pre-assembled on the housing, so that the compensating element is already secured in a pre-position relative to the output shaft and the housing. The compensating element is then displaced by a force acting on the actuating section in the radial direction, whereby the compensating element is displaced towards the output shaft. In the operating position, the compensating element can then be joined to the housing by ultrasonic welding while maintaining the set operating position. This avoids extensive measures to secure the compensating element in its operating position prior to welding.Particularly advantageously, the actuating section can be provided with a predetermined breaking point which, after the connection of the compensating element to the housing, makes it easy to remove any sections of the compensating element that may protrude from the housing by simply bending, knocking off, breaking off or the like.

[0021] The connection of the compensating element to the housing can, in principle, be made at any location. However, according to a particularly advantageous embodiment of the invention, the compensating element is connected to the housing cover by ultrasonic welding. This connection is particularly easy to manufacture and allows the housing cover to be provided with a section prepared for connection, which is particularly simple and cost-effective to implement compared to the corresponding design of the entire housing.

[0022] In order to prevent incorrect assembly of the compensating element relative to the output shaft, particularly when the contact surface in the housing has a shape inclined corresponding to the compensating element, the compensating element is designed according to a further embodiment of the invention such that its incorrect alignment relative to the output shaft is excluded. This ensures a predetermined arrangement of the compensating element in a particularly advantageous manner. The design can basically be implemented in any desired manner, with the compensating element particularly advantageously having a formation for its alignment, through which the compensating element has an asymmetric shape which, with a corresponding design of the housing, only allows one installation position. Projections, webs or elevations can be provided as the formation, which extend preferably along one side of the compensating element.

[0023] In principle, the connection of the compensation element to the housing, made by ultrasonic welding, already meets the stability requirements to withstand the loads that occur, so that the axial play-free arrangement of the output shaft can be reliably guaranteed.

[0024] According to a particularly advantageous embodiment of the invention, however, a locking bolt is embedded in the housing, preferably in the housing cover and the compensating element, in the area of ​​ultrasonic welding. A locking bolt extending through both the housing and the compensating element, or at least partial areas of these components, according to this embodiment of the invention additionally secures the position of the compensating element relative to the output shaft and the housing.

[0025] The placement of the locking bolt on the housing and the compensating element prior to ultrasonic welding also ensures that, after welding is complete, in addition to a force-locking and / or positive connection, there is also a material bond between the locking bolt, the housing, and the compensating element. The plastic melts during ultrasonic welding and firmly bonds the locking bolt to the housing and the compensating element. The use of a locking bolt increases the shear strength of the composite, allowing the locking bolt to transmit higher shear loads.

[0026] The design of the securing bolt is generally freely selectable, whereby it can also be formed by a simple cylindrical pin, which can be arranged, for example, in an advantageously provided bore in the compensating element and / or housing before carrying out the ultrasonic welding.

[0027] According to a particularly advantageous embodiment of the invention, however, the securing bolt has an end section that tapers toward the compensating element and / or a cross-section that changes in the longitudinal axis direction and / or a cross-section that deviates from a circular shape. According to this embodiment of the invention, the securing bolt can, for example, have a tip forming the tapered end section, which facilitates positioning of the securing bolt.

[0028] To improve the stability of the assembly consisting of the locking bolt, compensating element, and housing, the locking bolt can have a cross-section that varies along its longitudinal axis, with the outer surface featuring, for example, circumferential projections or a thread. This design, as well as axially extending webs or projections that result in a non-circular cross-section of the locking bolt, provides the locking bolt with numerous undercuts into which the plasticized plastic flows during the welding process, resulting in a particularly strong connection.

[0029] According to a particularly advantageous embodiment of the invention, the securing bolt is designed for coupling to an ultrasonic vibration generator and for transmitting ultrasonic vibrations into the housing and / or the compensating element. According to this embodiment of the invention, the securing bolt allows coupling or connection to an ultrasonic vibration generator, e.g., a sonotrode, and is further designed for transmitting ultrasonic vibrations into the housing and / or the compensating element.

[0030] According to this design, the preferably metallic securing bolt forms an extension of the sonotrode, allowing targeted heat introduction, which creates a particularly homogeneous connection. Following the ultrasonic welding process, the sonotrode is separated from the securing bolt, which then remains in its arranged position.

[0031] A further subject of the present invention is a method for producing an adjustment drive according to patent claim 12. The connection of the securing bolt to the ultrasonic vibration generator can take place both before and after the arrangement of the securing bolt on the housing and the compensating element. After the securing bolt is positioned and coupled to, for example, a sonotrode, the ultrasonic vibrations are then transmitted from the ultrasonic vibration generator to the securing bolt. After sufficient plasticization of the plastic surrounding the securing bolt and subsequent welding, the ultrasonic vibration generator is separated from the securing bolt after the ultrasonic welding process is completed. The design of the detachable connection between the securing bolt and the ultrasonic vibration generator can be implemented in any desired manner, provided that the transmission of the ultrasonic vibrations is ensured.

[0032] In principle, it is possible to design the locking bolt in such a way that it can be inserted into the housing and the compensating element at any point, whereby in particular a design of the locking bolt with a point and / or a thread, a knurling or similar is conceivable.

[0033] According to a particularly advantageous embodiment of the invention, however, the securing bolt is inserted into an opening, in particular a bore, previously made in the housing and / or the compensating element in order to establish engagement with the housing, in particular the housing cover and the compensating element.

[0034] This embodiment of the invention, where the opening can be present in both components or just one component, facilitates the arrangement of the locking bolt or the positioning of the locking bolt on the compensating element and the housing. The penetration depth of the locking bolt is generally such that, when installed, it does not protrude from the housing or the compensating element, i.e., into the interior of the adjustment drive or from the outer wall.

[0035] To create a particularly homogeneous and reliable connection, a further development of the method provides for the ultrasonic vibrations to be initiated over a predetermined time and / or until a predetermined amount of the plasticizing plastic around the securing bolt has spread. This embodiment of the invention, wherein the adjustable duration of ultrasound generation is generally based on empirical data or the ultrasonic welding is controlled by determining the amount of the plasticizing plastic, allows for a particularly reliable connection to be created, while the manufacturing process can be carried out particularly easily due to the specified parameters.

[0036] The plasticized plastic, which is defined as a molten plastic, enables a material-to-material connection between the housing, the compensating element, and the locking bolt, ensuring particularly reliable positioning of the compensating element in its operating position. Furthermore, the plasticized plastic can penetrate into any undercuts created by the design of the locking bolt, making the connection particularly reliable.

[0037] An embodiment of the invention is explained below with reference to the drawings. In the drawings: Fig. 1 a perspective view of an adjusting device with a housing and an output shaft protruding from the housing; Fig. 2 a plan view of the adjustment device of Fig. 1; Fig. 3 a view of a section along the section line AA of Fig. 2; Fig. 4 a perspective view of a housing cover of the housing of the adjustment device of Fig. 1; Fig. 5 a perspective view of a compensating element of the adjustment device of Fig. 1; Fig. 6 a perspective view of the housing cover of Fig. 4 and the compensating element of Fig. 5 in an assembly position; Fig. 7 a view of a section of another embodiment of an adjusting device with locking bolts and Fig. 8 a perspective view of the locking bolt of Fig. 7.

[0038] An embodiment of an adjustment drive 1 and its components is shown in the Fig. 1 to 6. The adjustment drive 1 comprises a housing 2 formed from a housing base 10 and a housing cover 3, on which an output shaft 4 of the adjustment drive 1 is rotatably mounted. The output shaft 4, which can be connected to an adjustable vehicle component not shown here, is driven via a pinion 12 shown only sketchily.

[0039] For the axial play-free arrangement of the output shaft 4 on the housing 2 required for trouble-free operation, the adjusting drive 1 has a wedge-shaped compensating element 5, which in the Fig. 1 and Fig. 3, the output shaft 4 is fixed in a position free of axial play. In the operating position, the compensating element 5 rests with a stop surface 16 on an axial stop 11 formed by the pinion 12 and with a support surface 13 on a contact surface 17 on the inside of the housing base body 10, which contact surface is inclined corresponding to the wedge shape of the compensating element 5. At the same time, in order to achieve an arrangement of the output shaft 4 free of axial play, the output shaft 4 rests with its shaft end arranged within the housing 2 with a conical, tapered support bearing 18 on the housing inner wall opposite the contact surface 17.The position of the output shaft 4 in the axial direction is determined depending on the radial position of the wedge-shaped compensating element 5 relative to the output shaft 4, so that the output shaft 4 is displaced into a play-free position by the displacement of the compensating element 5 in the radial direction.

[0040] The support bearing 18, like the area of ​​the housing base body 10 where the support bearing 18 rests against the housing inner wall, can be designed as desired to ensure positional stability and minimize friction. For example, the housing base body 10 can be provided in the area of ​​the support bearing 18 with a preferably metallic thrust washer (not shown here) that is attached separately or embedded in the housing base body 10 during the manufacturing process. As an alternative to the conical design shown, the support bearing 18 can be formed by a ball that is rotatably mounted on the shaft end.

[0041] To secure the operating position of the compensating element 5 relative to the housing 2, the compensating element 5 is connected to a web 8 of the housing cover 3, which extends radially toward the output shaft 4, via an ultrasonic welding spot 9. The positionally stable connection of the housing base body 10 and the housing cover 3, which, together with the housing base body 10, forms the radial bearing of the output shaft 4 via a section of the web 8 that is curved according to the cross-section of the output shaft 4, thus ensures the axial play-free position of the output shaft 4.

[0042] The position of the compensating element 5 on the output shaft 4 is determined, among other things, by a U-shaped receiving opening 15 which, in the operating position, extends in the area around the output shaft 4. A projection 6 is used to move the compensating element from a pre-position to the operating position. This projection runs, viewed in the radial direction, on the side of the compensating element 5 opposite the U-shaped receiving opening 15 and, in the pre-assembled and assembled position of the compensating element 5, protrudes through an opening 7 in the housing cover 3. In the pre-assembled position, the compensating element 5 can thus be moved towards the output shaft 4 into the operating position by conveniently moving the projection 6, which protrudes from the housing opening 7 of the already assembled housing 2, into the operating position, in which position the compensating element 5 is inseparably connected to the housing cover 3 by ultrasonic welding.

[0043] To achieve low friction between the axial stop 11 and the stop surface 16, these can, for example, be made of suitable materials or provided with low-friction coatings. According to an embodiment not shown here, a bearing, for example a ball bearing, can also be arranged between the pinion 12 and the compensating element 5, which enables particularly low-friction operation.

[0044] A formation 14 arranged on the one hand on the compensating element 5, which cooperates with a corresponding recess in the housing 2, enables a single mounting position of the compensating element 5 relative to the output shaft 4, so that it is ensured that the support surface 13 with a correspondingly inclined contact surface 17 comes to rest flatly on an inner wall of the housing base body 8.

[0045] In Fig.7 is a sectional view of a further embodiment of an adjusting device 1 with a securing bolt 19, wherein the securing bolt 19 extends through the web 8 of the housing 2 into the compensating element 5, so that the securing bolt 19 additionally secures the position of the compensating element 5 relative to the housing 2. The securing bolt 19 also serves to introduce the ultrasonic vibrations into the compensating element 5 and the housing 2, whereby the area around the securing bolt 19 is plasticized, i.e. melted, and an ultrasonic weld is produced. To introduce the ultrasonic vibrations, the securing bolt 19 is coupled to a sonotrode (not shown) before or after its arrangement on the housing 2 and the compensating element 5.

[0046] In order to ensure a particularly reliable arrangement of the securing bolt 19, it has a type of thread 20 on its circumference, into the spaces between which the plasticized plastic flows during ultrasonic welding, resulting in not only a positive but also a material-to-material connection of a particularly high quality.

[0047] During the ultrasonic welding process, the ultrasonic vibrations are converted into mechanical vibration energy via a sound transducer. The heat required for plasticizing during ultrasonic welding is achieved by introducing mechanical vibrations, which are then applied to the components 5, 8, 19 to be welded under a controlled contact pressure from a sonotrode. The design of the connecting bolt 19 serves to introduce heat in a targeted manner. Molecular and interfacial friction on the flanks of the thread 20 generates heat, in which the plastic begins to melt, causing the plasticized plastic to flow into the area between the flanks of the thread 20.

[0048] In order to enable a good arrangement of the locking bolt, the housing cover 3 intended for mounting on the housing 2 has a pilot hole which is adapted to the compensating element 5.

Claims

[1] Adjustment drive, in particular for a steering column adjustment or a vehicle seat of a motor vehicle, with - a housing (2), - an output shaft (4) rotatably mounted in the housing (2) and - a wedge-shaped compensating element (5) for preventing axial play of the output shaft (4), wherein the compensating element (5) is supported in its operating position on the housing (2) and an axial stop of the output shaft (4), characterized by that the compensating element (5) is connected to the housing (2) by means of ultrasonic welding to ensure the axial play-free arrangement of the output shaft (4) in its operating position and the compensating element (5) projects from a housing opening (7) with a projection (6) projecting radially relative to the output shaft (4). [2] Adjustment drive according to claim 1, characterized bythat the compensating element (5) has a U-shaped receiving opening (15) which surrounds the output shaft (4) in the region of a shaft shoulder forming an axial stop (11). [3] Adjustment drive according to claim 1 or 2, characterized by that the compensating element (5) in the operating position rests against a contact surface (17) of the housing with a support surface (13) facing away from the axial stop (11). [4] Adjustment drive according to one of the preceding claims, characterized by that the contact surface (17) is inclined in the opposite direction to a plane running vertically to the output shaft (4) in accordance with the wedge shape of the compensating element (5). [5] Adjustment drive according to one of the preceding claims, characterized by that the contact surface (17) is formed integrally with the housing (2). [6] Adjustment drive according to one of the preceding claims, characterized bythat the compensating element (5) is connected to the housing cover (3) by ultrasonic welding. [7] Adjustment drive according to one of the present claims, characterized by that the compensating element (5) is designed in such a way that its incorrect alignment with respect to the output shaft (4) is excluded. [8] Adjustment drive according to one of the preceding claims, characterized by that the compensating element (5) has a formation (14) for its alignment. [9] Adjustment drive according to one of the preceding claims, characterized by a securing bolt (19) embedded in the housing (2), preferably in the housing cover (3) and the compensating element (5), in the area of ​​the ultrasonic welding. [10] Adjustment drive according to one of the preceding claims, characterized bythat the securing bolt (19) has an end section tapering in the direction of the compensating element (5) and / or a cross-section changing in the longitudinal axis direction and / or a cross-section deviating from a circular shape. [11] Adjustment drive according to one of the preceding claims, characterized by that the securing bolt (19) is designed for coupling to an ultrasonic vibration generator and for transmitting ultrasonic vibrations into the housing (2) and / or the compensating element (5). [12] Method for producing an adjusting drive, with - a housing (2), - an output shaft (4) rotatably mounted in the housing (2) and - a wedge-shaped compensating element (5) for preventing axial play of the output shaft (4), wherein the compensating element (5) is supported in its operating position on the housing (2) and an axial stop of the output shaft (4), wherein the position of the compensating element (5) on the output shaft (4) is determined by a U-shaped receiving opening (15) on the compensating element (5), which in the operating position extends in the area around the output shaft (4), wherein the compensating element (5) is provided with a projection (6) projecting radially relative to the output shaft (4) for displacing the compensating element (5) from a pre-position into the operating position, wherein in a pre-assembled position of the compensating element (5) by displacing the projection (6), which projects from a housing opening (7) of an already assembled housing (2), the compensating element (5) is displaced in the direction of the output shaft (4) into the operating position, in which position the compensating element (5) is inseparably connected to the housing cover (3) by ultrasonic welding.

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