CN116136254A

CN116136254A - Bearing device, motor comprising such a bearing device and method for manufacturing such a bearing device

Info

Publication number: CN116136254A
Application number: CN202211425307.7A
Authority: CN
Inventors: L·博多
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2021-11-16
Filing date: 2022-11-15
Publication date: 2023-05-19
Also published as: DE102021212843A1

Abstract

The invention relates to a bearing arrangement for supporting a rotatable shaft by means of a bearing component, wherein the bearing component has a central bore for receiving the shaft and is arranged in a bearing cage which is inserted into a gear housing, wherein a first angular region defined at the outer circumference of the bearing cage is configured with a radially outer pressing surface by means of which the bearing cage is pressed into the gear housing and a second angular region defined at the inner circumference of the bearing cage is configured with a radially inner pressing surface by means of which the bearing component is pressed into the bearing cage and is arranged offset in a tangential direction relative to the second angular region.

Description

Bearing device, motor comprising such a bearing device and method for manufacturing such a bearing device

Technical Field

The present invention relates to a bearing device as well as an electric machine comprising such a bearing device and a method of manufacturing such a bearing device according to the preamble of the independent claims.

Background

DE 102 009 003 230 A1 discloses a device for supporting a shaft, in which a circular outer contour of a bearing body is inserted into a hexagonal inner contour of a bearing block. In bearing arrangements of this type with less defined radial contact surfaces, the problem arises that, due to the force action on the shaft and temperature fluctuations, precise positioning and orientation of the bearing body can only be achieved with great effort.

An alternative embodiment is therefore used, in which the bearing body is held in a bearing holder, which is inserted into the gear housing. In this embodiment, large friction fluctuations are produced between the bearing body and the bearing cage, which on the one hand can lead to disturbing vibrations and noise in the case of small friction and on the other hand can lead to tilting and uneven operation of the supported shaft in the case of high friction.

Disclosure of Invention

In contrast, the bearing arrangement according to the invention, as well as the electric machine comprising such a bearing arrangement and the method according to the invention for producing such a bearing arrangement, with the features of the independent claims have the advantage that the bearing cage is configured as an adapter element which flexibly supports the shaft in the gear housing. This is achieved by: an outer contact surface for pressing into the gear housing is formed on the bearing element, the radial force flow of which is decoupled from the radially inner contact surface of the bearing cage with which the bearing cage is radially held against the bearing body. The decoupling of the force flow is achieved by: the first angular regions of the radially outer pressing surfaces are not configured in relation to the tangential direction in superposition with the second angular regions of the inner pressing surfaces, but are configured to be twisted relative to one another by a defined offset angle. In this way, the pressing force is not transmitted directly in the radial direction via the bearing cage to the bearing element by the gear housing, but rather a certain mechanical movability of the bearing cage is achieved by the tangential angular deviations of the outer pressing surface and the inner pressing surface of the bearing cage, which bearing cage can also be influenced by the material used and/or the young's modulus of the material. The magnitude of the offset angle between the first and second angular regions of the outer and inner pressing surfaces makes it possible to reliably set the holding force of the bearing body in the bearing holder even in the range of large temperature fluctuations. The flexible design of the bearing cage also makes it possible to compensate for the different temperature coefficients of the different components in such a way that the holding torque of the bearing in the adapter element can be kept relatively constant over the temperature range.

Advantageous refinements and improvements of the embodiments specified in the dependent claims can be achieved by the measures recited in the dependent claims. Preferably, the radially outer pressing surface of the first angular region is formed by a radially outwardly projecting projection, which serves as a pressing rib. In this case, the outer diameter of the bearing cage is smaller in the angular region between the radially outer contact surfaces than in the outer contact surfaces. If such a bearing cage is pressed into a cylindrical receptacle in the transmission housing, the pressing force of the transmission housing is transmitted only in a first angular region of the outer pressing surface. In a second angular region in which the inner contact surface of the bearing cage is located, a radial play is produced here, for example, between the outer diameter of the bearing cage and the gear housing.

The radially inner pressing surface at the second angular region of the bearing cage preferably has a smaller inner diameter than the inner circumference of the first angular region having the radially outer pressing surface. The inner pressing surface can be configured as an inner pressing rib protruding radially inwards or can be produced by a radial recess which is cut out at the inner circumference of the bearing cage in a first angular region of the radially outer pressing surface. Since the bearing cage is preferably produced as an injection molded part made of plastic, the formation of the defined angular region with radially inner and/or outer elevations is synonymous with the formation of the radial recess in the respective other angular region at the inner periphery or at the outer periphery.

In a preferred embodiment, the first angular region with radially outer pressing surfaces does not tangentially overlap with the second angular region of radially inner pressing surfaces. The radially outer pressing force from the gear housing is thereby completely decoupled from the pressing force between the bearing cage and the bearing element. That is, no radially external pressing force is transmitted from the transmission housing directly in the radial direction to the bearing body arranged at the inner periphery of the bearing holder. Rather, the radially outer pressing force from the gear housing is deflected tangentially in the bearing cage and is transmitted radially inward to the bearing body in other angular regions. The bearing body thus has radial elasticity which can compensate for different material stretches, but also forces acting to different extents. The holding force of the bearing component in the bearing cage is thereby kept approximately constant in the operating range, or at least in a well-defined torque range.

It is particularly advantageous if the sleeve-shaped bearing cage has a slit in the axial direction over the entire radial thickness of the sleeve wall, which slit extends from the axial end into the bearing body in the axial direction. In this way, sections of the bearing cage are formed which are configured to be elastically movable in the radial direction relative to one another within certain limits. In this way, the bearing body can be introduced into the bearing cage in the axial direction in a simple manner. On the other hand, however, the annular section of the bearing cage can also be adapted flexibly to the forces occurring when installed in the transmission housing, for example in the event of temperature fluctuations. This also compensates for the inclination of the supported shaft relative to the gear housing.

At the axial end, the bearing cage has an annular region which runs uninterrupted in the circumferential direction, wherein the individual annular segment-shaped segments extend in the axial direction. The annular section can thereby be expanded at its axially free end in order to press in the spherical bearing, for example, in the axial direction. The axial slits preferably extend over a large part of the axial extent of the bearing cage in order to ensure sufficient radial flexibility of the individual ring segments.

At the axially free ends of the segments, opposite the circumferentially closed ring, the bearing cage has a radially outer flange which serves as an axial stop for the gear housing. The bearing cage can thus be pressed axially into the cylindrical receptacle in the gear housing up to the annular flange and thus can be positioned precisely.

In a first embodiment, the radially outer pressing surface is formed approximately centrally with respect to the circumferential direction on the annular section of the bearing cage. The radially inner pressing surface of the bearing body is adjacent to the axial slit at the tangential edge region of the annular section. The bearing body is thereby held radially by the bearing cage in the region of each axial slit, whereas the bearing cage is pressed radially outwardly into the gear housing centrally between the axial slits in the tangential direction.

The bearing arrangement according to the invention for supporting a shaft in a spherical bearing which is received by a bearing cage is particularly advantageous. In this case, the spherical bearing has an arch in the axial direction, which is inserted into a corresponding axially arched inner contour of the bearing seat. This means that the radially inner pressing surface of the bearing cage is also correspondingly formed at the bearing body in an arched manner in the axial direction. The spherical bearing can be particularly advantageously designed as a sintered bearing, which also serves as an oil reservoir for lubricating the shaft in the bearing body.

In an alternative embodiment, the radially outer pressing surface is arranged in a first angular region which extends in the tangential direction beyond the axial slit. On the other hand, the radially inner pressing surface facing the bearing body is arranged approximately centrally in the tangential direction between the axial slits. In this arrangement, the radially outer and/or inner pressing surface can also be formed by cutting a radially inner recess at the inner and/or outer periphery of the bearing cage. Preferably, the first and second angular regions do not overlap, so that the radially outer and inner pressing forces are decoupled from each other.

It is particularly advantageous if the bearing arrangement can be arranged in a transmission housing of the electric machine, wherein the shaft is driven, for example, by an electric motor. On the shaft, a worm gear is preferably formed as a meshing element, which meshes with a worm wheel mounted in the gear housing. The free end of the worm shaft is then supported in a bearing body which is arranged in the bearing cage according to the invention.

If different axial forces are applied to the shaft due to different load moments at the motor, the axial play of the shaft can be compensated by means of damping elements arranged at the axial ends of the shaft. The shaft is accommodated in the bearing body so as to be axially movable and is supported axially relative to the gear housing by a damping element. By flexibly designing and supporting the bearing cage, the force fluctuations acting on the shaft can be compensated for by the bearing arrangement according to the invention.

It is particularly advantageous if the bearing component, in particular the spherical bearing, can be pressed axially without a shaft into a bearing cage which at the same time serves as an adapter element for the shaft in the gear housing. The bearing holder is then inserted into the gear housing together with the bearing component, wherein only the angular region with the radially outer pressing surface bears radially against the gear housing. After this, the shaft, in particular the rotor shaft of the electric motor, can preferably be guided in the axial direction into a bearing member as a floating bearing. In this case, the flexibility of the bearing cage can be predefined by the geometric shaping and by the material properties of the bearing cage, whereby the holding force of the bearing body in the bearing cage can be set.

Drawings

Embodiments of the invention are illustrated in the accompanying drawings and explained in more detail in the following description. Wherein:

figure 1 shows a cross-section of a first embodiment of an electric machine according to the invention,

fig. 2 shows a view of a bearing cage according to the invention, as can be installed in fig. 1, and

fig. 3 and 4 show cross sections of different embodiments of the bearing arrangement according to fig. 1.

Detailed Description

Fig. 1 shows an embodiment of an electric machine 10, in which a rotor 16 of an electric motor 11 has a shaft 14 in the form of a rotor shaft 15, which is supported in a gear housing 20 by means of a bearing arrangement 12. The bearing arrangement 12 has a bearing cage 26, which is inserted into a receptacle 28 in the gear housing 20. The bearing cage 26 receives a bearing member 24 having an axial bore 25 in which the shaft 14 is rotatably supported. The bearing component 24 is embodied here, for example, as a spherical bearing, which has an approximately curved contour 30 in the axial direction 8, which is supported radially on an inner contour 31 of the bearing cage 26, which is correspondingly curved in the axial direction 8. The bearing component 24 is in this case only radially resting against the inner circumference 34 of the bearing cage 26 at a second inner angular region 42 of the bearing cage defined in the circumferential direction 9. The bearing cage 26 bears radially against the gear housing 20 at its outer periphery 33 at a defined first angular region 41. The first angular region 41 is here configured at a different position with respect to the circumferential direction 9 than the second angular region 42, as is shown in fig. 2. Fig. 1 schematically shows an electric motor 11 which is flanged to the gear housing 20, for example by means of a flange 62 of the stator housing 60, wherein the rotor shaft 15 of the rotor 16 protrudes from the stator housing 60 into the gear housing 20 in the axial direction 8. The shaft 14 is supported in the gear housing 20 by the bearing arrangement 12 in such a way that the engagement element 18, in particular the worm, engages with a gear wheel 22, in particular a worm wheel, of the gear 21. The shaft 14 is inserted with the free end 13 through the bearing member 24 and is axially supported at the washer 19. The spacer 19 bears axially against the axial damping element 17, whereby axial play of the shaft 14 can be compensated. The bearing device 12 is designed as a floating bearing, so that the shaft 14 is mounted in the bore 25 of the bearing component 24 in an axially movable manner. The drive torque of the electric motor 11 can then be supplied, for example, via a transmission 21 to a driven element 23 of a window lifter or a sliding roof or a seat adjustment mechanism for use in a motor vehicle.

Fig. 2 shows an enlarged view of the bearing cage 26 according to fig. 1. At the first axial side, the bearing cage 26 has a ring 54 closed over the circumferential extent, wherein a plurality of annular sections 51 extend in the axial direction 8, which are configured tangentially separated from one another by axial slits 52. The axial slit 52 is formed over the entire radial wall thickness 53 of the bearing cage 26. The annular flange 56 is thus also configured as a split annular flange 56 axially opposite the closed ring 54. The individual annular sections 51 are elastically configured in the radial direction 7, so that they open radially when the bearing component 24 is inserted axially. The bearing cage 26 together with the bearing component 24 is preferably pressed axially into the receptacle 28 in the gear housing 20, wherein the divided annular flange 56 is then supported, in particular axially, on the axial stop 29 of the receptacle 28. In fig. 2, the radially outer pressing surface 43 of the first angular region 41 is arranged at the outer periphery 33 of the bearing cage 26 in the circumferential direction 9 at the annular section 51. The radially outer pressing surface 43 has an outer diameter 45 that is greater than the second angular region 42, in whose inner circumferential edge 34 an inner pressing surface 44 is formed. The inner pressing surface 44 in turn has a smaller inner diameter 46 than the first angular region 41 having a larger outer diameter 45. The outer pressing surface 43 is in this case configured as a radially outwardly projecting pressing rib 47. A radial recess 48 is formed in the inner peripheral edge 46 of the bearing cage 26, which recess forms a radial air gap for the bearing component 24. An inner pressing surface 44 is formed tangentially between the radial recesses 48 at the inner periphery 46, and is supported radially on the bearing component 24. In the present exemplary embodiment, both the radially outer contact surface 43 at the outer peripheral edge 45 and the radial recess 48 at the inner peripheral edge 46 are formed in the first angular region 41, so that the radially outer contact surface 43 does not overlap the radially inner contact surface 44 of the second angular region 42 in this case with respect to the peripheral direction 9. In this case, both the radially outer contact surface 43 and the radial recess 48 at the inner peripheral edge 46 are also formed centrally in the respective annular section 51 in the peripheral direction 9, so that the radially inner contact surface 44 is formed on each side of the axial slit. The radially outer pressing surface 43 at the outer peripheral edge 45 and the radially inner pressing surface 44 at the inner peripheral edge 46 also preferably extend over the entire axial length 64 of the bearing member 24.

Fig. 3 shows the force flow according to the arrows at the cross section of the bearing arrangement 12 according to fig. 1. The bearing cage 26 is supported on the gear housing 20 only at a first angular region 41 having a radially outer pressing surface 43. In the first angular region 41, radial recesses 66 for the gear housing 20 are formed at the outer peripheral edge 33 of the bearing cage 26, so that radial pressing forces 71 from the gear housing 20 to the bearing cage 26 are limited to the first angular region 41. Conversely, the radial pressing force 72 between the inner peripheral edge 34 of the bearing cage 26 and the bearing component 24 is limited only to the second angular region 42 having the radially inner pressing surface 44. The force flow between the radial pressing force 71 and the radial pressing force 72 is shown as an arrow extending in the tangential direction 9. Between the inner pressing surfaces 44 in the circumferential direction 9, radial recesses 48 are formed, so that the bearing component 24 is not supported radially on the bearing cage 26 outside the second angular region 42. Here, there is no overlap between the first and second

angular regions

41, 42 in the circumferential direction 9. As a result, the interference fit between the bearing retainer 26 and the transmission housing 20 is decoupled from the interference fit between the bearing retainer 26 and the bearing member 24, thereby enabling a reliable and accurate bearing arrangement 12 for the shaft 14. The tangential transition from the inner pressing surface 44 to the radial recess 48 and also from the outer pressing surface 43 to the recess 66 can be formed as a step 68 or as a continuous transition 69.

Fig. 4 shows a further embodiment of the bearing device 12 in cross section, wherein the first angular region 41, which now has radially outer contact surfaces 43, is formed tangentially next to each other on both sides of the slit 52. In the region of the tangentially central portion of the annular section 51, a recess 66 for the gear housing 20 is formed at the outer periphery 33 of the bearing cage 26, and a radially inner contact surface 44 is formed at the central region of the inner periphery 34. In the present embodiment, the radially outer pressing surface 43 does not overlap the radially inner pressing surface 44 in the circumferential direction 9 either. In fig. 4, the transition between the two

angle regions

41, 42 forms a step 68, which is formed in particular at the outer peripheral edge 33 and in the inner peripheral edge 34 at the same angular position. The bearing holder 26 is preferably manufactured as a plastic part by means of injection molding. The radially outer pressing surfaces and the radially inner

pressing surfaces

43, 44, respectively the radial recess 48 and the radially outer recess 66, can be integrally formed with the bearing cage 26 without additional effort in terms of plastics. In an embodiment not shown, the radially outer pressing surface 43 in the circumferential direction 9 can also partially overlap the radially inner pressing surface 44 in the circumferential direction 9. In this exemplary embodiment, the bearing cage 26 has three ring segments 51, which can however also vary and are, for example, exactly two or four or five. In a further variant, the first and

second angle regions

41 and 42 can also be produced by: the receiving portion 28 and/or the peripheral surface of the bearing member 24 differs from an exact circular shape and has, for example, a polygonal shape with a plurality of planar mating pressing surfaces.

For assembly of the bearing device 12, the bearing component 24 is initially pressed axially into the bearing cage 26, the annular section 51 being elastically expanded in the radial direction 7. Thereafter, the bearing cage (26) is pressed together with the bearing component 24 into the receptacle (28) in the gear housing (20), wherein, in particular, the annular flange 56 is supported axially at the axial stop 29 of the receptacle 28. The shaft 14 together with the rotor 16 is preferably introduced into the bearing member 24 in the axial direction after the bearing member 24 together with the bearing cage 26 has been pressed into the gear housing 20.

It should be noted that various combinations of the individual features with one another are possible with regard to the embodiments shown in the figures and in the description. It is thus possible, for example, to change the geometry and specific configuration of the bearing cage 26 and of the bearing component 24 or to adapt it to the shape of the gear housing 20. The bearing element 24 can thus also in principle be configured as a cylindrical sleeve. The number and exact shape of the outer and inner

pressing surfaces

43, 44 and/or the radial recesses 48 and recesses 66 can be adapted to the requirements regarding temperature and vibration and the required holding torque. Instead of bearing at the end 13, the bearing arrangement 12 can also support the shaft 14 in the region of the axial middle. Such an electric machine 10 is particularly suitable for adjusting movable components in motor vehicles, in particular also for fastening directly at the motor cylinder of the vehicle. The motor 10 is preferably used as a window lifter drive or a seat adjustment drive or a sliding roof drive.

Claims

1. Bearing arrangement (12) for supporting a rotatable shaft (14) by means of a bearing member (24), wherein the bearing member (24) has a central bore (25) for receiving the shaft (14) and the bearing member (24) is arranged in a bearing cage (26) which is inserted into a gear housing (20), wherein a first angular region (41) defined at an outer periphery (33) of the bearing cage (26) is configured with a radially outer pressing surface (43), by means of which the bearing cage (26) is pressed into the gear housing (20), and a second angular region (42) defined at an inner periphery (34) of the bearing cage (26) is configured with a radially inner pressing surface (44), at which the bearing member (24) is pressed into the bearing cage (26), and the first angular region (41) is arranged offset in a tangential direction (9) relative to the second angular region (42).

2. Bearing device (12) according to claim 1, characterized in that the first angular region (41) of the radially outer pressing surface (43) is configured as a radially outwardly projecting pressing rib (47) having a larger outer diameter (45) than the second angular region (42) having the inner pressing surface (44).

3. Bearing device (12) according to claim 1 or 2, characterized in that the second angular region (42) of the radially inner pressing surface (44) is configured as a radially free-standing pressing surface (44) having a smaller inner diameter (46) than the first angular region (41) having the outer pressing surface (43).

4. Bearing device (12) according to any of the preceding claims, characterized in that a radial recess (48) is formed at the inner side of the bearing cage (26) in the region of the first angular region (41) with the radially outer pressing surface (43), at which recess the bearing component (24) does not bear radially against the bearing cage (26).

5. Bearing device (12) according to any of the preceding claims, wherein a first angular region (41) with the radially outer pressing surface (43) does not overlap in tangential direction (9) with a second angular region (42) with the inner pressing surface (44).

6. Bearing device (12) according to one of the preceding claims, characterized in that the bearing cage (26) has a plurality of ring segments (51) in the region of the circumference, which ring segments are configured radially elastically movable relative to one another in the radial direction (7), and in particular in that the ring segments (51) are separated from one another by axial slits (52) which extend over the entire radial wall thickness (53) of the bearing cage (26).

7. Bearing device (12) according to any of the preceding claims, wherein the bearing cage (26) has a closed ring (54) at axial ends in the circumferential extent, the axial slit (52) extending axially to the closed ring.

8. Bearing device (12) according to any of the preceding claims, characterized in that the bearing cage (26) has a split annular flange (56) axially opposite the closed ring (54), which annular flange axially abuts at a receiver (28) in the transmission housing (20).

9. Bearing arrangement (12) according to any one of the preceding claims, characterized in that the bearing member (24) is configured as a spherical bearing, which approximately has a curved outer contour (30) in the axial direction (8) and is manufactured in particular from a sintered metal material.

10. Bearing device (12) according to any one of the preceding claims, characterized in that a first angular region (41) with the radially outer pressing surface (43) is arranged approximately centrally between two adjacent axial slits (52) at the annular section (51), and that a second angular region (42) with the inner pressing surface (44) is arranged on both sides in the circumferential direction (9) next to adjacent opposite slits (52) to the axial direction.

11. Bearing device (12) according to any one of the preceding claims, characterized in that a first angular region (41) with the radially outer pressing surface (43) is arranged next to adjacent on both sides at an axial slit (52) at the ring section (51), and a second angular region (42) with the inner pressing surface (44) is arranged approximately centrally between two adjacent axial slits (52) at the ring section (51) in the circumferential direction (9).

12. An electric motor (10) having a rotor (16) and a transmission (21) and having a bearing arrangement (12) according to any one of the preceding claims, wherein the shaft (14) is designed as a rotor shaft (15) of the rotor (16) and has a meshing element (18) which meshes with a transmission gear (22), in particular a worm gear, of the transmission (21) arranged in the transmission housing (20).

13. An electric machine (10) according to claim 12, characterized in that the bearing arrangement (12) is configured as an axial floating bearing and the shaft (14) is axially movably supported in the bearing member (24) and that an elastic damping element (17) for axial play compensation is arranged at the free end (13) of the shaft (14).

14. Method for producing a bearing arrangement (12) according to any one of claims 1 to 11, wherein the bearing component (24) is first pressed axially into the bearing cage (26) and thereafter the bearing cage (26) is pressed into a receptacle (28) of the transmission housing (20), wherein the shaft (14) is introduced axially into the bearing component (24), in particular after the bearing component (24) together with the bearing cage (26) has been assembled in the transmission housing (20).