Bearing device, reduction gear, electromechanical power steering and method for connecting a drive element of an electromechanical power steering to a bearing device

Description

[0001] The present invention relates to a bearing device for a reduction gear for an electromechanical power steering system, comprising a first end and a second end opposite the first end, wherein a contact section is provided between the first end and the second end, and a bearing section for supporting a drive element.

[0002] Furthermore, the present invention relates to a reduction gear comprising a drive element meshing with a helical gear, wherein the drive element is designed as a shaft which is arranged in a gear housing and is rotatably mounted about an axis of rotation at its first end and at its second end in the gear housing.

[0003] Furthermore, the present invention relates to an electromechanical power steering system comprising an electric motor with a motor shaft and a reduction gear.

[0004] Finally, the present invention relates to a method for connecting a drive element of an electromechanical power steering system with a bearing device which rotatably mounts the drive element in a gearbox housing about an axis of rotation and preloads it in the direction of a helical wheel.

[0005] Reduction gears of the type mentioned above are frequently used in motor vehicles to assist steering movements or, in the case of steer-by-wire steering systems, to solely convert a steering command into a corresponding steering movement.

[0006] In the first case, reduction gears of the type mentioned above are used in an electromechanical power steering system of a motor vehicle, wherein the power steering system has an input shaft connected to a steering wheel, via which the driver initiates steering commands in the form of steering torques. An output shaft connected to the input shaft transmits the steering torques to the wheels to be steered via tie rods, i.e., pivotable components of a vehicle steering system.

[0007] Reduction gears of the type mentioned above, also known as power steering systems, are typically used to apply auxiliary torque to the output shaft, a steering pinion, or a rack. The reduction gear of the type mentioned above is controlled by determining the torque applied by the driver via the steering wheel to the input shaft with respect to the output shaft.

[0008] In reduction gears of the type mentioned above, particularly when designed as electromechanical power assist devices for electromechanical power steering systems of the type mentioned above, it is known to apply the respective assist force by means of an electric motor. That is to say, a drive torque generated by the electric motor is converted into the assist force (steering force) and then transmitted to the aforementioned tie rod, in particular via a toothed engagement with a rack.

[0009] For this purpose, the electric motor is typically coupled to a drive worm, either by directly attaching the drive worm to a motor shaft of the electric motor, or by means of a gearbox connected between the electric motor and the drive worm. The drive worm acts on a worm gear, which transmits the drive torque to the actual steering system, for example via a gearbox, a rack and pinion mechanism, or a belt drive. The reduction gear of the type mentioned above can then provide the assist force, for example in the area of ​​the steering shaft, the steering pinion, or the rack.

[0010] A reduction gear of the type mentioned above is known from DE 10 2013 003 749 A1. In the known reduction gear, the drive worm is supported in a housing of the known reduction gear by means of a bearing. A bearing arrangement for supporting a shaft is known, for example, from DE 10 2008 056 024 A1.

[0011] A disadvantage of the current state of the art is that manufacturing or assembly-related inaccuracies, wear effects, and contamination—either individually or in combination—lead to a less than optimal meshing between the worm gear and the worm for energy-efficient and low-maintenance operation of a reduction gearbox of the type mentioned above. In other words, the bearing arrangement of the worm and / or the motor shaft driving the worm is disadvantageous.

[0012] The object of the present invention is to provide a bearing device of the type mentioned at the outset, a reduction gear of the type mentioned at the outset and a method of the type mentioned at the outset, by which the disadvantages of the prior art are circumvented.

[0013] The problem is solved by the features of independent claims 1 and 13. Advantageous further developments result from the respective dependent claims.

[0014] According to the invention, this problem with regard to the bearing device is solved by the bearing section being designed as an opening which projects from the first end towards the second end, and a recess which projects from the second end towards the first end, wherein the opening is radially spaced from the recess. Preferably, the bearing device according to the invention is designed as a bearing bushing with a preferably round cross-section.

[0015] Preferably, the bearing device is designed to support the drive element with preload along the axis of rotation. In other words, the drive element is fixed, particularly against deflection along the axis of rotation. This is advantageous because it provides axial support that counteracts any axial deflection of the drive element, such as the worm gear or motor shaft.

[0016] Preferably, the drive element is mounted with elastic preload along the axis of rotation by the bearing device according to the invention. By mounting the drive element with elastic preload, for example by a restoring means, in particular a spring element, a compliant mounting of the drive element is advantageously provided with respect to changes in shape and / or form, so that even in the event of a change in shape and / or form, the drive element is mounted by a bearing force along the axis of rotation caused by an elastic preload, preferably by a radial and / or axial preload. In other words, the drive element is mounted adaptively within a certain range with respect to changes in shape and / or form, so that secure mounting is ensured for a multitude of cases.Furthermore, mechanical stresses in the drive element are reduced or even avoided when its spatial expansion increases, for example, due to thermal expansion. Changes in the shape and / or form of the drive element include, but are not limited to, changes in shape and / or form due to moisture, thermal expansion, thermal shrinkage, elastic / plastic / elastic-plastic deformation, and / or abrasion.

[0017] In the bearing device according to the invention, the opening is at least partially cylindrical and has a base. The opening is particularly preferably completely cylindrical. Furthermore, it is conceivable and possible for the opening to have a thread, knurling, and / or coating. It is also possible for the opening to be conical or funnel-shaped. Preferably, the base section has a projection, particularly preferably a concentric projection. The drive element then contacts the bearing device and thus the base section axially via the projection, thereby reducing the corresponding mean friction diameter. This reduces friction. This is particularly advantageous when the bearing device is mounted with axial preload against the drive element.In the bearing device according to the invention, the recess is radially circumferential and has a recess base. Preferably, the depth of the opening is greater than or equal to the depth of the recess. Furthermore, it is conceivable and possible for the recess to have a deeper depression than the opening.

[0018] In an advantageous embodiment of the bearing device according to the invention, the recess is annular in shape. The recess surrounds the opening; preferably, the recess and the opening are arranged or can be arranged concentrically. Particularly preferably, the recess is shaped such that the bearing device is W-shaped or M-shaped in a longitudinal section, for example, along a rotational axis of the drive element.

[0019] In an advantageous embodiment of the bearing device according to the invention, the recess is conical. Other shapes are also conceivable and possible, such as the funnel shape.

[0020] In an advantageous embodiment of the bearing device according to the invention, the bearing device has a wall thickness, wherein the recess has a volume whose value is greater than the cubic wall thickness. Preferably, the wall thickness is a minimum, maximum, or medium wall thickness, and particularly preferably a minimum wall thickness. The cubic wall thickness is the value of the wall thickness multiplied by itself three times. Preferably, the wall thickness is a maximum wall thickness or a medium wall thickness, and particularly preferably, the wall thickness is a minimum wall thickness of the bearing device.

[0021] In the bearing device according to the invention, a radial distance between the opening and the recess is formed that is smaller than a first distance between the recess base and the end face of the first end and / or smaller than a second distance between the opening base and the end face of the second end. Preferably, the radial distance towards the first end of the bearing device is larger than towards the second end. Furthermore, in another advantageous embodiment, a second radial distance is provided between the recess and the outer circumferential surface of the contact section. The second radial distance is greater than or equal to the first radial distance. Preferably, the second radial distance is larger towards the first end than towards the second end.

[0022] In an advantageous embodiment of the bearing device according to the invention, the second distance between the opening bottom and the end face of the second end is less than or equal to the first distance between the recess bottom and the end face of the first end.

[0023] In an advantageous embodiment of the bearing device according to the invention, the bearing device is formed in one piece.

[0024] In an advantageous embodiment of the bearing device according to the invention, this comprises a plastic, more preferably it is made of a resin material and / or coated with a plastic, preferably POM, PA, PEEK or PTFE.

[0025] In an advantageous embodiment of the bearing device according to the invention, at least one projection is provided on an outer circumference of the contact section. In another advantageous embodiment of the bearing device according to the invention, the bearing section has one or more recesses, which are particularly intended for storing and / or transporting lubricant.

[0026] In an advantageous embodiment of the bearing device according to the invention, the projection of the opening and the recess onto a projection plane are free of overlap with each other, in particular orthogonal or parallel to a longitudinal axis of the bearing device. In other words: the projected edges of the recess and the opening do not intersect and do not overlap.

[0027] In an advantageous embodiment of the bearing device according to the invention, it has an elastically pre-tensionable clamping means for pre-tensioning the bearing device against the drive element.

[0028] In a further advantageous embodiment, the bearing section of the bearing device forms a bearing means for the sliding support of the drive element, in particular a bearing means designed as a radial bearing for the sliding support of the drive element. This is advantageous because this measure provides, for example, a rolling element-free radial bearing, in particular a plain bearing, which can be prevented from radially deflecting by a positive fit with the drive element, i.e., a worm gear or a motor shaft. For example, a section or area of ​​a plain bearing supporting the drive element is designed as a sleeve and / or bushing that spatially surrounds the drive element, preferably as a hollow cylinder. In particular, the bearing means is designed as a fixing means for radially fixing the drive element.

[0029] Plain bearings for solid friction, fluid friction, or a corresponding mixed friction are particularly suitable. The material(s) for such a bearing device designed as a plain bearing are particularly suitable as one or more plastics, but also, additionally or alternatively, one or more ceramics and / or graphite and / or one or more sintered metals. The bearing device is preferably made of a plastic. In particular, the bearing device is an injection-molded part.

[0030] In an advantageous embodiment, the bearing device can be arranged in a frictional connection with the drive element, particularly in a bearing seat of a housing that at least partially accommodates the bearing device. This allows the drive element to be additionally and / or supplementarily supported against deflection from a predetermined position by a corresponding frictional force exerted by the bearing device. This is achieved primarily through the contact section of the bearing device. Furthermore, the bearing device can be arranged, i.e., mounted, in the aforementioned bearing seat without any further measures for interaction with the drive element. Because the bearing device can be arranged in a frictional connection with the drive element, the drive element is also movably mounted, particularly with respect to deflection along the axis of rotation.

[0031] According to a preferred embodiment, the bearing device is elastically deformable, particularly the contact section, so that it can be mounted in the bearing seat in a substantially elastically reversible manner. For example, the bearing device can be elastically preloaded in the radial direction, so that in a mounted state, it is pressed against, for example, an inner wall of a bearing seat provided for mounting the bearing device by a corresponding force that restores the elastic deformation. A further advantage is that the bearing device is self-centering in the radial direction relative to the drive element in the bearing seat, or is designed to be self-centering.

[0032] In an advantageous embodiment, the bearing device is designed to supply lubricant to a contact area formed between the bearing device and the drive element. Accordingly, in an advantageous embodiment, the bearing device according to the invention preferably has one or more recesses, preferably channel-shaped recesses, in particular one or more grooves, in the bearing section provided for supporting the drive element, for storing and / or transporting lubricant to and / or within the contact area, so that the contact area is supplied with lubricant during the execution of the rotary movement. This advantageously results in low-friction and therefore low-maintenance and low-wear operation of the bearing device according to the invention. The bearing device can also include so-called lubrication pockets.

[0033] In a further advantageous embodiment, the bearing device is preloaded against the drive element. This is advantageous because the drive element is preloaded in the driven state by and / or via the bearing device, so that the drive element remains supported by the bearing device, particularly with low friction, by applying a corresponding preload force. Preferably, the bearing device is mounted axially against the drive element. Preferably, the bearing device is elastically preloaded, i.e., in the sense of a spring, in that the contact section is preloaded by its insertion into the bearing seat.

[0034] In a further advantageous embodiment of the bearing device according to the invention, it features an elastically preloadable clamping device for preloading the bearing device against the drive element. This is advantageous because, on the one hand, it allows for a suitable bearing arrangement for the drive element, and on the other hand, the clamping device provides a measure adapted and thus optimized for counteracting any deflection of the drive element, namely through a corresponding design of the clamping device. Preferably, the clamping device is ring-shaped, for example as a preload ring or retaining ring, or disc-shaped, for example as a preload disc or retaining disc. This is particularly advantageous when the clamping device is to interact with the bearing device.

[0035] It is further advantageous if the clamping device has at least one protrusion. The protrusion advantageously acts like a spring element, through which a preload force can be exerted on the drive element, for example, in the manner of a disc spring. Furthermore, changes in the length of the drive element, particularly along the axis of rotation, can be compensated particularly well by elastic deformation of the protrusion. It is especially advantageous if the protrusion contacts, or can be arranged to contact, the drive element and / or the bearing device with a convex side defined by the shape of the protrusion.

[0036] In a further advantageous embodiment, the clamping device is designed to be self-locking. This is advantageous because the clamping device can be arranged, for example, in a bearing seat to apply a preload force in a predetermined position without requiring any structural or other modifications to the bearing seat to mount the clamping device there. This is achieved, for example, by arranging the clamping device transversely to the direction along which the preload force is to be applied or can be applied (e.g., a preload force for an axially elastic compression state of the drive element) in a friction-fit manner, and / or by mechanically anchoring it to the bearing seat due to a surface structure of the clamping device.Mechanical anchoring can be achieved by pressing the clamping device, in its assembled state, against a bearing seat due to its elastic deformation, particularly radially. It is especially advantageous if the clamping device partially penetrates an inner wall of the bearing seat, for example, due to a suitable material selection and / or radial preload force. This means that the clamping device has a higher hardness (e.g., according to Vickers) than a corresponding area of ​​the bearing seat, at least in the area intended for assembly. A meandering surface structure of the clamping device is particularly well-suited for such interlocking and / or anchoring. This embodiment is especially advantageous when the clamping device is shaped as a ring or disc and the bearing seat is hollow cylindrical.The clamping device preferably has a circular inner section which can be in direct contact with the sliding bearing. Fan-shaped, S-shaped, wave-shaped, or curved segments project radially inward or, preferably, outward, from the circular section and are bent inwards, respectively, and are in contact with the housing wall. These segments are preferably integrally formed with the circular inner section and form an edge. It is also conceivable and possible for at least one tab, tongue, or tooth to project radially outward from the circular section into the housing wall, wherein the at least one tab, tongue, or tooth can be radially pre-tensioned, so that the edge of the clamping device can be designed in a star-shaped or toothed configuration. The edge can also have slots for improved pre-tensioning.

[0037] In a further advantageous embodiment, the bearing device has a contact section for force-fit contact with an area intended for supporting the bearing device. According to the invention, at least one projection is provided on an outer circumference of the contact section. This is advantageous because the bearing device can be arranged, for example, in a bearing seat enclosed by a housing, such as the gearbox housing, without further measures for interaction with the drive element, and thus can be mounted. Furthermore, the bearing device can only be displaced axially with respect to a deflection of the drive element once a predetermined frictional force is exceeded, and the bearing element is preloaded by one or more projections in the housing.The circumcircle diameter of the bearing device in the area of ​​the projections is larger than in the areas of the outer surface of the bearing device without projections.

[0038] The projection(s) can be formed, in particular, by a thread turned into and / or on the outer circumference with one or more threads and / or by knurling, especially in the case of a bearing element designed as a radial bearing, particularly a plain bearing, a corresponding longitudinal knurling (extending in the axial direction of the radial bearing) and / or transverse knurling (extending in the circumferential direction of the radial bearing), or by a combination thereof. Alternatively and / or additionally, the projection(s) can also be shaped like knobs. An advantage of the described projections (thread and / or knurling and / or knob-like) is that the bearing assembly can be displaced, for example, with a constant force, especially in the axial direction with respect to the drive element, so that a bearing clearance can be set via a corresponding force control.The aforementioned projections can deform the bearing device, particularly partially or completely elastically, plastically, or elastic-plastically, when installed. The contact section can be designed, in particular, as a spring beam.

[0039] In a further advantageous embodiment of the bearing device according to the invention, the clamping means exerts a preload force on the contact section in a clamped state. This is advantageous because it reduces the frictional force against the drive element caused by the preload force, particularly in the axial direction, especially in the case of a drive element configured as a motor shaft.

[0040] In a further advantageous embodiment, the clamping device, in a clamped state, exerts a preload force on a contact section of the bearing device that at least partially receives the drive element. This is advantageous because it maximizes the effective preload force acting on the drive element. The bearing section is preferably designed as an opening that is cup-shaped and has a bottom section. In other words, the bearing section can be designed as a blind hole in the sliding bearing. The opening is preferably cylindrical.Furthermore, it is conceivable and possible that the opening of the bearing section, corresponding to the contour of the section of the drive worm in contact with it, may be formed on the inner circumference by a turned thread with one or more thread turns and / or by knurling, in particular by a corresponding longitudinal knurling (extending in the axial direction of the radial bearing) and / or transverse knurling (extending in the circumferential direction of the radial bearing), or by a combination thereof.

[0041] Preferably, the bearing device has at least one rolling element that can be arranged or is arranged between the opening and the drive element.

[0042] The problem is solved with regard to the reduction gear mentioned at the outset by the fact that the reduction gear comprises a bearing device according to one of the attached claims and / or embodiments disclosed herein.

[0043] In an advantageous embodiment of the reduction gear according to the invention, the shaft is at least partially received at its first end and / or at its second end in the opening of the bearing device, preferably in such a way that a positive locking connection between the bearing device and the shaft can be enabled.

[0044] In a further advantageous embodiment of the reduction gear according to the invention, the bearing device pre-tensions the shaft in an axial and / or radial and / or orthogonal direction to the axis of rotation.

[0045] In an advantageous embodiment of the reduction gear according to the invention, the bearing device has a contact section for force-fit contact with an area of ​​the gearbox housing provided for bearing the bearing device, wherein at least one projection is provided on an outer circumference of the contact section.

[0046] In an advantageous embodiment of the reduction gear according to the invention, the shaft is a worm shaft and the worm gear is a worm wheel.

[0047] The problem is solved with regard to the aforementioned electromechanical power steering by designing a reduction gear according to one of the attached claims and / or embodiments disclosed herein, wherein the motor shaft drives the shaft.

[0048] In an advantageous embodiment of the electromechanical power steering system according to the invention, the helical wheel is arranged in a rotationally fixed manner on a steering shaft of a motor vehicle.

[0049] The problem is solved with regard to the aforementioned method by the following steps: a) providing the drive element; b) providing the bearing device; c) providing the gearbox housing comprising an opening; d) positioning the drive element and the bearing device in the opening of the gearbox housing relative to each other; and e) pressing the drive element into the opening of the bearing device with a defined clamping force, so that the drive element is pre-tensioned by the bearing device along the axis of rotation. This is advantageous because it fixes the drive element, particularly along the axis of rotation, against deflections of the drive element. Preferably, force-controlled pre-tensioning is carried out in step e).

[0050] Preferably, the bearing assembly is partially inserted into the opening of the gearbox housing. Particularly preferably, the drive element, especially a shaft, is partially inserted into the opening of the bearing assembly at its first end and / or its second end.

[0051] Preferably, the bearing device in the gearbox housing is preloaded in an axial and / or radial and / or orthogonal direction via at least one projection of the bearing device.

[0052] If the drive element is also elastically pre-stressed, a bearing that is compliant with respect to changes in shape and / or form of the drive element is advantageously created. Furthermore, this measure provides a bearing that resists deflection of the drive element.

[0053] Preferably, the drive element is mounted with elastic preload in step e). It is even more advantageous if the drive element is mounted with such preload that it is elastically preloaded or elastically compression-preloaded, so that it is pressed (pushed) against the drive means in the driven state.

[0054] In an advantageous embodiment of the method according to the invention, the bearing device is provided in step b) with a bearing arrangement designed for the sliding support of the drive element, and the drive element is supported by the bearing device in step d). According to this measure, a bearing device is positioned in and / or on the drive element, for example, if the drive element is designed as the motor shaft of an electric motor, at an end of the motor shaft spaced away from the electric motor, so that the bearing device supports a corresponding section of the drive element. Preferably, the bearing device is arranged in a force-fit manner, so that it is movably supported in the event that the deflection of the drive element exceeds a predetermined value. Particularly preferably, the drive element is fixed by the bearing device in the radial direction against deflections of the drive element.

[0055] In a further advantageous embodiment of the method according to the invention, in step b) the bearing device is provided with an elastically preloadable clamping device, and in step c) the preloading is carried out by clamping the clamping device against the bearing device. This is advantageous because a reduction gear is manufactured such that, in a bearing seat that spatially at least partially encloses the drive element, the bearing device is first positioned on the drive element for supporting the drive element, and then the clamping device is positioned in the bearing seat and then preloaded, preferably by force control, so that the bearing device is elastically preloaded against the drive element.

[0056] In a further advantageous embodiment of the method according to the invention, the drive element is driven in step d) and / or e). This is advantageous because a bearing clearance adapted to the driven state of the drive element can be advantageously set. Preferably, the drive element is driven by an electric motor.

[0057] In a further advantageous embodiment of the method according to the invention, in step e) the preloading is terminated when an operating parameter of a drive element reaches a predetermined value. The predetermined value of the operating parameter can be an electric current and / or an electric voltage and / or a braking torque of an electric motor. This advantageously sets a bearing clearance adapted to the driven state of the drive element.

[0058] In a further advantageous embodiment of the method according to the invention, the following steps are provided: Positioning a clamping ring in the opening of the gearbox housing; preloading the bearing device with a defined preload force by pressing the clamping ring against the bearing device.

[0059] The invention is described in a preferred embodiment by way of example with reference to a drawing, further advantageous details of which can be seen in the figures of the drawing.

[0060] Functionally identical parts are marked with the same reference symbols.

[0061] The figures in the drawing show, in detail: Figure 1: A schematic perspective view of a steering system; Figure 2: A reduction gear according to a first embodiment in a longitudinal section along a worm shaft; Figure 3: A reduction gear according to a second embodiment in a longitudinal section along a worm shaft; Figure 4: Exploded view of essential components of the reduction gear according to the invention Figure 2 Figure 5: a bearing device according to the invention in a perspective view according to a first embodiment of the bearing device; Figure 6: the bearing device according to Figure 5 in a top view from the front as shown in Figure 5 Figure 7: a cross-section through the bearing device according to Figure 5Figure 8: a cross-section through a bearing device according to the invention in a second embodiment; Figure 9: a bearing device according to the invention in a perspective view according to a third embodiment of the bearing device; Figure 10: a cross-section through the bearing device according to Figure 9 Figure 11: a cross-section through a bearing device according to a further embodiment; Figure 12: a cross-section through a bearing device according to a further embodiment; Figure 13: a cross-section through a bearing device according to a further embodiment.

[0062] In Figure 1Figure 1 shows a schematic representation of an electromechanical power steering system 1, in which a driver can apply a corresponding torque as a steering command to a steering shaft 3 via a steering wheel 2. The torque is then transmitted via the steering shaft 3 to a steering pinion 5, which meshes with a rack 6, which in turn transmits the specified steering angle to the steerable wheels 8 of the vehicle via corresponding tie rods 7, which contact a road surface 80.

[0063] The electromechanical power steering 1 has an electric power assist 10 with an electric motor 9 and a Figure 1 not visible reduction gear 11 (see Figure 2) according to the invention, so that the auxiliary power assist 10 is effectively connected via the reduction gear according to the invention to the rack 6 for the transmission of an auxiliary force (steering force) to the rack 6, namely via a meshing engagement of a pinion in a (not shown here) in Figure 1 unseen area of ​​the rack 6.

[0064] The steering shaft 3 in the Figure 1 further includes a universal joint 4, by means of which the course of the steering shaft 3 in the motor vehicle can be adapted to the spatial and / or structural conditions.

[0065] In the Figure 2The reduction gear 11 of the power assist 10 is shown in a longitudinal section. The longitudinal section runs along a rotational axis 120 of a worm shaft 13, which is driven by the electric motor 9. The electric motor 9 has a motor shaft 14, which is rotationally fixed to the worm shaft 13 via a flexible coupling 50. The worm shaft 13 meshes with a worm gear 60. The worm gear 12 is rotationally fixed to a pinion 70, which meshes with the rack 6 analogously to the pinion 5. In In a driven state, the worm gear 12 and thus the pinion 70 rotate about a rotary axis 110. The aforementioned components are mounted in a common gearbox housing 100.

[0066] Figure 2Figure 1 shows that the motor shaft 14 and the worm shaft 13 are each supported at a motor-side end 140 of the worm shaft 13 in a rolling bearing 130, which is designed as a ball bearing. The worm shaft 13 further has an end 150 furthest from the motor, which is supported in a bearing assembly according to the invention. The bearing assembly according to the invention comprises a bearing assembly designed as a sliding bearing 200 and a clamping ring 210. The bearing assembly 200 is clamped by the clamping ring 210 against a shoulder 220 of the worm shaft 14, so that the worm shaft 13 is axially compressed along the axis of rotation 120 by the bearing assembly 200. The clamping ring 210 is supported radially against a wall 230 of a bearing seat 240 transversely to the axis of rotation 120 by being elastically preloaded accordingly.The bearing device 200 is arranged in the bearing seat 240 by means of a frictional engagement, whereby a contact section 250 of the bearing device, which is designed as a spring beam, is supported against the wall 230 due to an elastic preload of the contact section 250. The bearing device 200 can then be displaced along the axis of rotation 120 by applying a predetermined force and thus inserted into the bearing seat 240.

[0067] Figure 3 shows a reduction gear 300 according to the invention in a second embodiment in a longitudinal section analogous to Figure 2In contrast to the reduction gear 11, the worm shaft 13 is supported at its end 150 furthest from the motor by a rolling bearing 320. The end 140 of the worm shaft 13 closest to the motor is supported in a bearing assembly 310, which is preloaded against the motor shaft 14 by a clamping ring 330. The bearing assembly 310 is designed to be pass-through to the end 140 of the worm shaft closest to the motor, unlike the bearing assembly 200.

[0068] Figure 4 An exploded view shows the storage device according to the invention. Figure 3 , which includes the clamping ring 210 and the bearing device 200, as well as the worm shaft 13 and the electric motor 9. The aforementioned components are shown separated in such a way that they appear in a correspondingly assembled state, as in Figure 2The components are arranged relative to each other as shown. The components are assembled as follows: The worm shaft 13 is connected at its end 140 near the motor to the motor 9 to transmit motor torque to the worm shaft 13. Then, the bearing assembly 200 is positioned at the end 150 furthest from the motor of the worm shaft 13, so that the end 150 furthest from the motor is radially supported in a bearing section 260 of the bearing assembly 200, i.e., the area that radially supports and thus surrounds the end 150 furthest from the motor. The clamping ring 210 is then pressed against the bearing device 200, so that, depending on the distance along the axis of rotation 120, the clamping ring 210 exerts a correspondingly large (relatively small distance to the bearing device 200) or a small preload force (relatively large distance to the bearing device 200) on the bearing device 200 and thus on the worm shaft 13, when the clamping ring 210 clamps the bearing device at its Figure 2The visible, convex side is contacted. The worm shaft 13, the bearing device 200, and the clamping ring 210 form a component group. From Figure 4 It is also evident that the bearing device has 200 press ribs 205.

[0069] The Figures 5 and 6 Figure 1 shows the bearing device 200 in perspective view and in top view. On a surface 207 of the bearing device 200, i.e., the surface which, in the assembled state of the bearing device 200, faces the wall 230, the bearing device 200 has the press ribs 205, i.e., projections, such that the bearing device 200 is subjected to elastic or elastic-plastic deformation of the press ribs 205 by applying a relatively constant displacement force into the bearing seat 240 (alternatively, as in Figure 2). Figure 3(as can be seen) is introduced and thereby assembled. If the worm shaft 13 is driven by the electric motor 9 during the assembly of the clamping ring 210 in the bearing seat 240, the clamping ring 210 can be pre-tensioned, i.e., displaced against the bearing assembly 200, due to the constant displacement force of the bearing assembly 200 relative to the wall 230 provided by the press ribs 205, so that it is pressed against the worm shaft 13, specifically the shaft shoulder 220, at the end 150 furthest from the motor, at a predetermined clamping force and thus by a corresponding, so-called delta force cut-off of the electric motor 9. The press ribs 205 are oriented axially along the longitudinal axis 120 of the worm shaft 13 in the assembled state of the bearing assembly 200.

[0070] From the sectional view according to Figure 7It is evident that the bearing device 200 has a radially circumferential contact section 250 shaped as a spring beam, which in turn has the surface 207. In other words, the bearing device 200 is pressed against the wall 230 in the assembled state, in particular by a self-recovering elastic deformation of the contact section 250.

[0071] From the Figures 5 and 6 and in particular the sectional view according to Figure 7 Furthermore, the bearing section 260 of the bearing device 200 is visible, which, in the assembled state, i.e., when the bearing device 200 is pressed against the end 150 of the drive worm 13 furthest from the motor for its axial fixation, spatially and physically encloses the worm shaft 13 at the end 150 furthest from the motor in the sense of a sleeve. Since the contact area 250 is designed as a spring beam, as can be seen in particular from Figure 7As can be seen, the elastic deformation in the described assembled state of the bearing device 200 (see in particular Figure 2 ) so that the bearing section 260 experiences virtually no radial elastic deformation, which has a positive effect on low-friction bearing of the worm shaft 13 in the bearing section 260. In other words, the bearing section 260 is mechanically decoupled from the contact section 250 under radial load. The opening 260 can be cup-shaped or cup-shaped. Alternatively, the opening 260 can also be a through-hole. From Figure 6 It is also evident that a longitudinal axis 120 is defined by the bearing device 200.

[0072] Out of Figure 7 It is evident that the surface 207 and a recess 253 are spaced apart from each other in the radial direction by a distance b2. From Figure 7It is further evident that the bearing section 260 or the corresponding opening of the bearing device 200 and the recess 253 are spaced apart from each other by a distance b1. From Figure 7 It is further evident that the recess 253 has a recess base 254 and that the recess base 254 and an end face of a first end 251 of the sliding bearing 200 are spaced apart from each other by a distance d1. Figure 7 It is further evident that an opening bottom 261 and an end face of a second end 252 of the sliding bearing 200 are spaced apart from each other by a distance d2. The aforementioned distances are proportional to each other in Figure 7 The distances mentioned define the corresponding wall thicknesses of the bearing device 200.

[0073] The distance b1 corresponds to the wall thickness of a wall located between the opening 260 and the recess 253. The distance b2 corresponds to the wall thickness of a wall located between the surface 207 and the recess 253. Preferably

[0074] From the sectional view according to Figure 8 A bearing device 400 of a further bearing device according to the invention is shown without a representation of the clamping ring 210, which, in contrast to the bearing device 200, has radially arranged recesses 270 in the bearing section 260 or in the corresponding opening of the bearing opening for storing and / or transporting lubricant, so that in the Figure 2 The visible, assembled state of the bearing device 200, which can be transferred to the bearing device 400, shows that the worm shaft 13 is supplied with lubricant upon contact with the bearing section 260.

[0075] The Figures 9 and 10Figure 1 shows a bearing device 500 of a further bearing device according to the invention, without showing the clamping ring 210. The bearing device 500 is designed analogously to the bearing device 200, except that the surface 207 has projections 510 formed by a thread. Corresponding threads run in a tangential direction or transversely to the axis of rotation 120, in an analogous manner to Figure 2 Assembled state of the plain bearing 500.

[0076] Figure 11 Figure 1 shows a cross-section through a bearing device 202 of another bearing device according to the invention. The bearing device 202 is designed analogously to the bearing device 200, except that it has a concentric projection 256 that extends into the bearing section 260 or the opening of the bearing device 202. InIn its assembled state, the bearing device 202 can then contact the motor-remote end 150 or the motor-proximal end 160 of the worm shaft 13 via the projection 256 in the direction of the axis of rotation 120. The projection 256 ensures that the friction between the bearing device 202 and the worm shaft 13 is reduced. The projection 256 extends into the opening 260. In its assembled state, the bearing device 202 can then contact the drive shaft 13 via the projection 256 in the direction of the axis of rotation 120.

[0077] Figure 12 Figure 1 shows a cross-section through the bearing device 202, where the bearing device 202 is designed here without the projection 256. The bearing device 202 has a needle bearing 270, so that the end 150 furthest from the motor or the end 160 closest to the motor of the worm shaft 13 is supported radially in the bearing section 260 via the needle bearing 270 or corresponding rolling elements.

[0078] Figure 13shows a cross-section through the bearing device 202, wherein the bearing device 202 has the projection 256 and the needle bearing 270.

Claims

1. A bearing device (200, 202, 310, 400, 500) for a reduction gear (11) for an electromechanical power steering system, comprising a first end (251) and a second end (252) opposite the first end (251), wherein a contact portion (250) is provided between the first end (251) and the second end (252), and a bearing portion (260) for supporting a drive element (13), wherein the bearing portion (260) is formed as an opening extending from the first end (251) toward the second end (252), and a recess (253) extends from the second end (252) toward the first end (251), wherein the opening (260) is radially spaced apart from the recess (253), the opening (260) is at least partially circular-cylindrical in shape, and the opening (260) has an opening bottom (261), wherein at least one projection (205) is provided on an outer circumference (207) of the contact portion (250), characterized in that the recess (253) is formed to extend radially around the circumference and has a recess bottom (254).

2. Bearing device (200, 202, 310, 400, 500) according to claim 1, characterized in that the recess (253) is annular and / or conical.

3. Bearing device (200, 202, 310, 400, 500) according to one of the preceding claims, characterized in that the bearing device has a wall thickness, wherein the recess (253) has a volume whose value is greater than the cubic wall thickness.

4. Bearing device (200, 202, 310, 400, 500) according to claim 1 or 2, characterized in that a radial distance (b1) between the opening (260) and the recess (253) is less than a first distance (d1) between the recess bottom (254) and the end face of the first end (251) and / or smaller than a second distance (d2) between the opening bottom (261) and the end face of the second end (252), and wherein preferably the second distance (d2) between the bottom of the opening (261) and the end face of the second end (252) is less than or equal to the first distance (d1) between the bottom of the recess (254) and the end face of the first end (251).

5. Bearing device (200, 202, 310, 400, 500) according to any one of the preceding claims, characterized in that the bearing device is formed integrally and / or from a resin material.

6. Bearing device (200, 202, 310, 400, 500) according to any one of the preceding claims, characterized in that the bearing portion (260) has one or more recesses (270).

7. Bearing device (200, 202, 310, 400, 500) according to any one of the preceding claims, characterized in that the bearing device (200, 202, 310, 400, 500) comprises an elastically preloadable clamping means (210, 330) for preloading the bearing device (200, 202, 310, 400, 500) against the drive element (13).

8. A reduction gear (11, 300) comprising a drive element (13) meshing with a screw gear (12), wherein the drive element is designed as a shaft which is arranged in a gear housing (100) and is mounted at its first end (140) and at its second end (150) in the gear housing (100) about an axis of rotation (120), characterized in that the reduction gear (11) comprises a bearing device (200, 202, 310, 400, 500) according to one of claims 1 to 7, wherein the shaft (13) is preferably received at least partially in the opening (260) at its first end (140) or at its second end (150).

9. Reduction gear (11, 300) according to claim 8, characterized in that the bearing device (200, 202, 310, 400, 500) preloads the shaft (13) in the axial and / or radial direction relative to the axis of rotation (120).

10. Reduction gear (11, 300) according to one of claims 8 or 9, characterized in that the bearing device (200, 202, 310, 400, 500) has a contact portion (250) for force-fitting engaging with a region (230) of the gear housing provided for mounting the bearing device (200, 202, 310, 400, 500), wherein at least one projection (205) is provided on an outer circumference (207) of the contact portion (250).

11. Reduction gear according to any one of the preceding claims 8 to 10, characterized in that the shaft (13) is a worm shaft and the screw wheel (12) is a worm wheel.

12. An electromechanical power steering system comprising an electric motor (9) with a motor shaft and a reduction gear (11) according to any one of claims 8 to 11, wherein the motor shaft drives the shaft (13), and wherein, in particular, the screw wheel (12) is fixedly mounted on a steering shaft (70) of a motor vehicle for conjoint rotation therewith.

13. Method for connecting a drive element (13) of an electromechanical power steering system to a bearing device (200, 202, 310, 400, 500) which rotatably supports the drive element (13) in a gear housing (100) about an axis of rotation (120) and preloads it in the direction of a worm wheel (12), characterized in that the method comprises the following steps: a) providing the drive element (13); b) providing the bearing device (200, 310, 400, 500, 210, 330) according to one of claims 1 through 7; c) providing the gear housing (100) comprising an opening (240); d) positioning the drive element (13) and the bearing device (200, 202, 310, 400, 500, 210, 330) in the opening (240) of the gear housing (100) relative to one another; and e) pressing the drive element (13) into the opening (260) of the bearing device (200, 202, 310, 400, 500) with a defined clamping force, such that the drive element (13) is mounted by the bearing device (200, 202, 310, 400, 500, 210, 330) in a preloaded manner along the axis of rotation.

14. A method according to claim 13, characterized in that the following step is provided: positioning a clamping ring (210, 330) in the opening (240) of the gear housing (100); preloading the bearing device (200, 202, 310, 400, 500) with a defined preload force by pressing the clamping ring (210, 330) against the bearing device (200, 202, 310, 400, 500).