WO2014064188A1

WO2014064188A1 - Device for supporting a shaft

Info

Publication number: WO2014064188A1
Application number: PCT/EP2013/072259
Authority: WO
Inventors: Dieter Schuler; Dirk DEICHMANN; Horst Roellecke; Zoltan SZENTIRMAI; Wolfgang Winkler
Original assignee: Robert Bosch Gmbh
Priority date: 2012-10-25
Filing date: 2013-10-24
Publication date: 2014-05-01
Also published as: DE102012219556A1

Abstract

The invention relates to a device (10) for supporting a shaft (12), having a bearing (14) receiving the shaft (12), the bearing itself being received in a bearing mount (16) in a housing or housing part (18). The device (10) is characterized in that a bearing tilting moment (M) of the bearing (14) relative to the bearing mount (16) can be influenced in a targeted manner via lever arms (a, b, c; a', b', c') on the shaft (12) in at least one spatial direction (x, y), wherein a point-wise press-fit is provided between the bearing mount (16) and an outer contour of the bearing (14), by means of which the bearing (14) contacts the bearing seat (16) at least at three contact points (20; A, B, C; A', B', C').

Description

Device for supporting a shaft

description

The invention relates to a method for supporting a shaft, with a shaft receiving bearing, which is accommodated in a bearing seat of a housing or housing part, according to the preamble of the independent claim.

State of the art

Electric motors consist of fixed (pole housing with magnets, brush holder) and rotating (armature) components and assemblies. The required storage is often done by dome sintered bearings, which are soaked in oil. These are held by so-called elastic retaining springs in correspondingly shaped recesses in brackets or bearing caps, which are usually deep drawn from steel. The molded bearing seat represents the bearing seat and requires this. a high degree of shape and position tolerances. Deviations lead to the installation of the bearing to non-ideal component axes of symmetry, especially in engine assembly.

From DE 196 52 929 A1 rolling bearings for receiving an armature shaft of an electric motor in a transmission housing are known, which adjoins a motor housing of the electric motor. Usually, the required tight fit of the rolling bearing is produced via a frictional connection by means of a press fit in the housing, which is realized by pressing with an oversize. During the pressing in, the bearing follows the given contour, resulting in one

Deviations from the cylindrical shape of the housing seat can also be transferred to the pressed-in bearing. On the other hand, deviations from the concentricity of the housing seat from the ideal dimension, ie displacements between the center of the bore and the component axis of symmetry, can be maintained after assembly. The same applies to the parallelism error of

Bore axis based on the component axis of symmetry. Since an ideal component axis of symmetry due to the usual

Manufacturing tolerances due to complex manufacturing processes of components can not be realized inexpensively, are generally used for the bearing caps forming manufacturing processes such as stamping, deep drawing, etc. and used as a bearing sintered spherical bearings. Cup bearings provide some alignment of the bearing axis of symmetry with the shaft axis of symmetry over the limited ability to align in the bearing seat. A measure of this is the so-called Lagerkippmoment.

The Lagererkippmoment represents one of the key features to achieve aligned bearing shaft symmetry axes. However, it must not be too small, as this could affect the storage behavior during operation (spinning) and thus noise. Similarly, a too large overturning moment makes it difficult to align the calotte. The Lagerkippmoment is therefore generally defined with a nominal value and a tolerance value. Stamped or deep-drawn bearing caps make it possible to date no symmetric Lagerkippmomente especially if the outer contour of the motor housing or bearing cap strongly asymmetric design features in terms of length / width ratio.

From DE 10 2009 003 230 A1 discloses a bearing for supporting a shaft is known in which a bearing component is received in a bearing seat of a housing. For ease of manufacture, to reduce vibrations and to increase the precision of the bearing, the outer contour of the bearing component and the inner contour of the bearing seat have different geometries, so seen in the circumferential direction, the facing contact surfaces of bearing component and bearing seat only partially flat, line or punctiform lie together.

Advantages of the invention

It is the object of the invention to provide a device with which the bearing tilting moment of a bearing held in a bearing seat is defined with respect to certain preferred directions for reducing material distortions or to 360 ° circumferentially evenly large realize. This object is achieved by a device for supporting a shaft, with a shaft receiving bearing, which is accommodated in a bearing seat of a housing or housing part. According to the invention the Lagererkippmoment the bearing is relative to the bearing seat via lever arms of the shaft targeted in at least one

Spatial direction influenced, being between the bearing seat and a

Outer contour of the bearing a punctual interference fit is provided by means of which the bearing rests against at least three contact points on the bearing seat. This results in an advantageous manner that only the raised areas of the bearing seat represent the investment / support zones for the camp, so that the Lagererkippmoment depends on the tangential orientation of the contact zones. Taking into account the distortion zones of the material (with influence on the shape and position tolerances of the bearing seat), in particular in the case of asymmetrical outer contours of the housing or housing part, the bearing tilting moment can be influenced in a targeted manner by orientation of the bearing points. This is particularly advantageous with regard to downstream assembly processes

(Caulking a bearing cap on the pole housing of an electric motor, Axialkraftbeaufschlagung on the bearing cap for plastic deformation) with consequent contour influencing the bearing seat and influence on the Lagererkippmonent (asymmetrical characteristic).

Furthermore, the contact points depending on the desired spatial direction are oriented where the slightest material distortion on the bearing seat of the housing or housing part and thus the highest precision of the bearing seat with respect. Form u. Position tolerances is achieved. It is advantageous in this

Connection, if the contact points are spherical or pointed designed to allow targeted tilting of the bearing.

Depending on the bearing seat and the outer contour of the housing or housing part, it may be advantageous if the contact points are arranged distributed in each case 120 ° or not equidistant over the Au ßenkontur of the camp. Depending on the material delay, the contact points can be arranged axially symmetrically or asymmetrically relative to the desired spatial direction are.

The invention is used in a particularly advantageous manner in an electric motor, wherein the shaft is a motor shaft of the electric motor and the housing or the housing part is a motor housing or a bearing cap of the electric motor and wherein the bearing is a sintered or solid plain bearing.

Further advantages of the invention will become apparent from the features specified in the dependent claims and from the drawings and the description below.

embodiments

drawing

The invention is explained below by way of example with reference to FIGS 1 to 5, wherein like reference numerals in the figures indicate the same components with the same operation.

Show it

1 shows a section through the device according to the invention for defining the Lagererkippmoments,

2 shows a first embodiment of the device according to the invention in a perspective view,

3: the first embodiment of the device according to the invention in a schematic representation,

4 shows a second embodiment of the device according to the invention in a perspective view, 5 shows the second embodiment of the device according to the invention in a schematic representation and

6 shows a third embodiment of the device according to the invention in a schematic representation.

Description of the embodiments

FIG. 1 shows a first exemplary embodiment of the invention

Device 10. A shaft 12 of an electric motor not shown in detail is mounted in a bearing 14, which may be formed as a solid or sintered bearing. The bearing 14 is by means of a press fit to a bearing seat 16 of a housing or housing part 18 of the electric motor. Depending on the outer contour of the housing or housing part 18 and in connection with the selected manufacturing process, material distortions with certain preferred directions can generally occur, which in turn influence the shape and position tolerances of the bearing seat 16. By design of the bearing seat 16 in the form of a punctual contact with the outer contour of the bearing 14 and corresponding tangential alignment of the contact points 20, a bearing tilting moment M of the bearing relative to the bearing seat 16 can be selectively influenced taking into account the component distortion. Depending on the length L of the shaft 16 and the applied force F in a defined spatial direction, the Lagererkippmoment results in Ncm to M = F x L. It should be noted that the electric motor is mentioned only as an example and the invention also for other applications with appropriate storage of a bearing 14 for a shaft 12 in a bearing seat 16 is suitable.

FIGS. 2 and 3 show a first embodiment of the invention

Device 10 according to the invention in a perspective and a schematic view. The Lagererkippmoment M of here

Overview not shown bearing 14 can be derived via corresponding lever arms of the shaft 16 simplified and selected for two

Represent spatial directions over an x and a y coordinate. The x and y Axial directions represent symmetry axes of the housing part 18, in which the bearing seat 16 is located.

The acting lever arms a, b, c with respect to the contact points 20 in the y-direction result in the Lagererkippmoment M _y , which is referred to as M _ytA function of the tangential orientation tA1. If the contact points 20 are distributed over the circumference of the outer contour of the bearing 14 as contact points A, B, C of α = 120 °, M _{y tA results} in M _ytA1 (a, b , c).

Since a, b = small and c> a, b, this results in a comparison with a complete, spherical system with circumferentially circumferentially radius c acting

Investment zone of the bearing 14 following relationship:

M _ytA i (a, b, c) <M (fully spherical unit).

Thus, as shown above by way of example for the selected tangential orientation tA1, the bearing tilting moment can be specifically influenced in a spatial direction with respect to the completely spherical installation, which can prove advantageous with regard to material distortion zones of the housing or housing part 18.

In the case of a housing or housing part 18 with an asymmetrical outer contour, an advantageous position of the contact points 20 is furthermore obtained by arranging them in accordance with the tangential orientation tA2. This is illustrated in FIGS. 4 and 5 for a second exemplary embodiment of the device 10 according to the invention. In contrast to FIGS. 2 and 3, the three contact points Α ', B', C are now rotated by -90 ° with respect to the x and y coordinates.

In a circumferential distribution of the bearing points Α ', B', C to each other of = 120 ° results M _{y tA2} depending on the lever arms a ', b' to M _{y tA2} (a ', b'). Since, at a bearing tilting moment in the y-direction, a '= a, b' = b and c = 0, the following relationship arises in comparison with the tangential orientation tA1: M _yt A2 (a ', b') <M _{y tA} i (a, b, c).

Thus, as shown above by way of example for the selected tangential orientation tA2, the bearing tilting mount can specifically influence the y-direction of the space in order to compensate the material distortion zones. In addition, the influence _{parameter of} the division α of the points A 'to B' can be used in particular for the further reduction of M _{y tA2} . If α <120 ° selected, M _{y tA2} can be further reduced compared to M _{y tA2} (a ', b'), since the acting lever arms a 'and b' continue to shrink.

The above-described principle has been exemplified on the Y-axis of a

asymmetrical housing or housing part 18 described. However, this principle can be applied to any desired spatial direction. Advantageously, it will then apply when it is known where the delay zones of the housing or housing part 18 are to unbalanced

Compensate for bearing tilting moments.

FIG. 6 shows a further exemplary embodiment of the invention

Device 10 shown in which the contact points 20 are formed pointed instead of spherical. The relationships between the lever arms and the Lagererkippmomenten are unchanged from Figure 3. However, due to the different configuration of the contact points, different results

Coefficient of friction. In general, therefore, any dimensions (length, width, height) and shapes (spherical, conical, pointed, etc.) of the contact points 20 are conceivable.

Finally, it should be noted that the shown

Embodiments neither on the figures 1 to 6 nor on an application in an electric motor and the embodiment of the housing or

Housing part 18 is limited. Thus, as a housing or housing part 18 also differently shaped bearing caps, Poltöpfe or the like can be used. Of course, the invention is also applicable in connection with generators or other appropriately held shaft bearings.

Claims

1 . Device (10) for supporting a shaft (12), having a shaft (12) receiving bearing (14) which is accommodated in a bearing seat (16) of a housing or housing part (18), characterized in that a Lagererkippmoment (M ) of the bearing (14) relative to the bearing seat (16) via lever arms (a, b, c; a ', b', c ') of the shaft (12) is selectively influenced in at least one spatial direction (x, y), wherein between the bearing seat (16) and an Au ßenkontur the bearing (14) a punctual interference fit is provided by means of which the bearing (14) at least three

Abutment points (20; A, B, C; Α ', B', C) bears against the bearing seat (16).

2. Device (10) according to claim 1, characterized in that the contact points (20; A, B, C; Α ', B', C) are configured spherical or pointed.

3. Device (10) according to any one of the preceding claims, characterized in that the contact points (20; A, B, C; Α ', B', C) are distributed over the Außenkontor of the bearing (14) arranged such that a Material distortion of the housing or housing part (18) in dependence on the desired spatial direction (x, y) is minimal.

4. Device (10) according to one of the preceding claims, characterized in that the contact points (20; A, B, C; Α ', B', C) are arranged distributed in each case by 120 ° over the outer contour of the bearing (14) ,

5. Device (10) according to one of the preceding claims 1 to 3, characterized in that the contact points (20; A, B, C; Α ', B', C) are not distributed equidistant over the outer contour of the bearing (14) are.

6. Device (10) according to one of the preceding claims, characterized in that the contact points (20; A, B, C; Α ', B', C) relative to desired spatial direction (x, y) are arranged axisymmetric.

7. Device (10) according to one of the preceding claims 1 to 5, characterized in that the contact points (20; A, B, C; Α ', B', C) are arranged asymmetrically relative to the desired spatial direction (x, y) ,

8. Device (10) according to any one of the preceding claims, characterized in that the bearing (14) is a sintered or solid sliding bearing.

9. Device (10) according to any one of the preceding claims, characterized in that the shaft (12) is a motor shaft of an electric motor and that the housing or the housing part (18) is a motor housing or a bearing cap of the electric motor.