GB2488003A

GB2488003A - A rolling element bearing

Info

Publication number: GB2488003A
Application number: GB1121321.2A
Authority: GB
Inventors: Juergen Haecker
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-02-11
Filing date: 2011-12-09
Publication date: 2012-08-15
Also published as: CN102635631A; GB201121321D0; DE102011003982A1; CN102635631B; FR2971569A1

Abstract

A rolling element bearing 30 is provided. The bearing 30 comprises: an inner rotary body 38; at least one rolling element 34 revolving on the inner rotary body 38; and an outer rotary body 36 revolving with the at least one rolling body 34. The bearing is adapted such that, by means of a drive device 46, a torque can be passed in to one of the inner rotary body 38, rolling body 34 and outer rotary body 36, and, by means of an output device 48, a torque can be drawn off from another of the inner rotary body 38, rolling body 34 and outer rotary body 36. In this case the connection to the output device 48 is via a coupling between a bearing cage of the bearing 30 and a cup-shaped extension 42 to transfer torque to an output shaft 44.

Description

Be a ring

Prior art

The invention relates to a bearing having an inner rotary body, at least one rolling body revolving on the inner rotary body, and an outer rotary body revolving at the at least one rolling body. Further, the invention relates to the use of such a bearing.

Bearings of the said type are used in a great variety of ways in machines and installations, for the purpose of supporting and rotatably mounting, in particular, shafts on associated housing components. In suoh cases, an inner rotary body is supported in the radial direction in relation to an outer rotary body. The rotary motions mentioned here in this connection are to be understood as being relative to one another, this being intended to include a rotary body as such also being able to be disposed in a stationary manner, while at least one other body rotates, or revolves, relative to the latter.

The bearings in such cases are used, in particular, for the purpose of rotatably mounting the shaft of an electric motor on electric-motor drives.

Disclosure of the invention

Created according to the invention is a bearing having an inner rotary body, at least one rolling body revolving on the inner rotary body, and an outer rotary body revolving at the at least one rolling body, wherein the bearing is adapted such that, by means of a drive device, a torque can be passed in to a body from the group inner rotary body, rolling body and outer rotary body, and, by means of an output device, a torque can be drawn off from another of the three elements inner rotary body, rolling body and outer rotary body.

The bearing designed thus according to the invention acts at the same time as a planetary gearing, by means of which a torque can be transferred from a drive device onto an output device and is at the same time converted in respect of its magnitude. With the torque conversion, conversion of the rotational speed is at the same time effected between the drive device and the output device.

In the case of the "planetary gearing" constituted in this way by means of a rolling bearing, the inner rotary body acts as a sun, the at least one rolling body acts as a planet, and the outer rotary body acts as an internal gear. The torque to be converted is passed in to one of the bodies and is drawn off from another body. Since this is effected by means of the rolling bearing and its components, no additional gearing is required for torque conversion. Accordingly, for the arrangement as a whole, it is possible to keep to low costs and also a small structural space.

The rotary bodies of such a bearing arrangement according to the invention act as radial support elements and, at the same time, as torque converters, or torque transmitters. Between the bodies, or elements, the forces for torque transfer are in this case transferred, in a particularly advantageous manner, solely by means of force closure, or frictional closure. In the case of a force closure, or a force-closure connection between two objects, mutual displacement of these objects is prevented as long as a counter-force, caused by static friction, is not exceeded. If a load force acting tangentially upon the objects is greater than their static frictional force, the force closure is lost and the surfaces of the objects slip, or move relative to one another.

The at least one rolling body is preferably surrounded by a bearing cage, which is adapted to act as a drive device for passing in a torque, or as an output device for drawing off a torque.

In this arrangement, the at least one rolling body thus acts as a planet that is held, or guided, on a planet carrier. The planet carrier is constituted by the bearing cage. In the case of known rolling bearings, such a bearing cage is often provided in any case, in order to prevent mutual rubbing of the rolling bodies against one another. The development with this bearing cage can be created in a correspondingly cost-neutral or, at least, very cost-effective manner.

Advantageously, the bearing cage is provided with a cup-shaped extension for transferring the passed-in or drawn-off torque onto a shaft.

The cup-shaped extension serves as a transfer element, by means of which the torque can be passed from the region of the bearing cage, i.e. from a radially rather outer region of the arrangement, into the centre thereof. Located in the centre of the arrangement in this case there is, in particular, a shaft, to which the extension transfers the torque and which can consequently act, in particular, as an output shaft.

Preferably provided inside the cup-shaped extension there is a further bearing, by means of which the extension can be supported radially on the inner rotary body. The extension and, -4-.

consequently, the bearing cage can thus be positioned and held radially in a simple and cost-effective manner, thereby making it possible to prevent frictional losses and wear, particularly on the bearing cage.

Preferably, further, the inner rotary body is designed so as to be stationary.

The transfer of torque is then effected between the rotating outer rotary body and the at least one rolling body or, in particular, the bearing cage. Preferably, in this case, the outer rotary body, in particular, is driven. The bearing cage then revolves more rapidly than the outer rotary body, whereby an increase in rotational speed is created.

Alternatively, in the case of the bearing arrangement according to the invention, the outer rotary body is designed so as to be stationary.

The transfer of torque then occurs between the rotating inner rotary body and the at least one rolling bearing or, in particular, the bearing cage. For this purpose, advantageously, the inner rotary body, in particular, is driven. The bearing cage then rotates more slowly than the inner rotary body, whereby a reduction in rotational speed is created.

The invention further provides for the use of such a bearing according to the invention on a drive, in particular an electric-motor drive such as, in particular, an electric motor.

An exemplary embodiment of the solution according to the invention is explained more fully in the following with reference to the appended schematic drawings.

The figure shows a longitudinal section of an exemplary embodiment of a bearing according to the invention, together with an associated drive.

The figure shows a drive 10, which is constituted by an electric motor 12. The electric motor 12 in this case can generate a torque at an output shaft 14.

The electric motor 12 is designed with a housing pot 16 that is substantially closed by a housing cover 18, which is on the right side in respect of the figure. The housing pot 16 is part of a stator 20 of the electric motor 12, which stator acts together with a rotor 22 inside the stator 20 in the conventional manner in order to generate the said torque.

The rotor 22 comprises a drive shaft 24, which is supported radially relative to the housing pot 16 by means of a bearing 26, in particular in the form of a plain bearing, a needle bearing or a ball bearing. The drive shaft 24 is further coupled to a slipring contacting 28 for the purpose of transferring electrical energy to the rotor 22 in this manner.

Further, the drive shaft 24 is supported both radially and 1 Ifl 1 _----j' -1 dX±ct±J.jI Lt±dLiVt LU LI1t I1ULtSLf1 (2UVtL i-C U/ iEtdI15 Ut d uear±iiy 30 in the form of a ball bearing. The bearing 30 thus constitutes both a radial bearing and an axial bearing, and is designated as a so-called fixed bearing of the drive shaft 24, while the bearing 26 constitutes the movable bearing, which has a certain axial freedom of movement.

The bearing 30 is constituted by an inner ring 32 and a multiplicity of rolling bodies 34 in the form of balls.

Further, the bearing 30 has an outer ring, as an outer rotary body 36, which surrounds the rolling bodies 34 radially outwards, such that the latter roll, on the one hand, on the inner ring 32 and, on the other hand, on the outer rotary body 36. A so-called inner rotary body 38 is thus constituted by the S drive shaft 24 and the inner ring 32.

The rolling bodies 34 are surrounded by a bearing cage 40, which extends as a circular ring, or circular sleeve, between the inner ring 32 and the outer ring, as an outer rotary body 36, and which in this case surrounds the individual rolling bodies 34 in such a way that the latter are encompassed at their "equator" by the bearing cage 40, while with their "poles" they bear against the inner ring 32 and the outer ring.

The bearing cage 40 is coupled to a cup-shaped extension 42 in a torque-transferring manner, in particular is realized so as to be integral therewith, which extension adjoins the bearing cage on the right in respect of the figure. The cup-shaped extension 42, for its part, is coupled in a torque-transferring manner to a shaft 44 that adjoins the extension 42 yet further to the right.

In the case of such a drive 10, the stator 20 and the rotor 22 constitute a drive device 46, by means of which a torque can be passed in to the drive shaft 24 and the inner ring 32 (as an inner rotary body 38). The rolling bodies 34, the bearing cage 40, the extension 42 and the shaft 44 constitute an output device 48, by means of which a torque can then be drawn off from the drive 10. The inner ring 32 in this case acts together with the rolling bodies 34 and the bearing cage 40 in the manner of a planetary gearing, whereby the rotational speed of the drive shaft 24 is reduced down to the rotational speed of the shaft 44 without a separate gearing being required for this purpose.

For the purpose of supporting the shaft 44, in particular in the radial direction, a needle bearing 50 is in this case disposed inside the cup-shaped extension 42, by means of which needle bearing the drive shaft 24 is supported, with its end region, against the inner circumferential surface of the extension 42.