Brakes – Operators – Electric
Patent
1997-01-10
1999-02-23
Oberleitner, Robert J.
Brakes
Operators
Electric
188163, B60L 700
Patent
active
058734368
DESCRIPTION:
BRIEF SUMMARY
The invention concerns an electromagnetic hysteresis brake of the kind defined in detail in the preamble of claim 1.
A hysteresis brake of this kind has been disclosed in the ZF-Katalog "Hysteresis Clutches and Brakes" KB 2.
Electromagnetic hysteresis brakes have been used, for example, in textile machines as so-called thread brakes. The typical feature of such machines is a plurality of production units which are arranged in series and have comparatively the same process cycle.
The individual thread brakes are centrally controlled electrically. This means that the torque, for an optimal process cycle, is adjusted via current. But all brakes must here have precisely the same torque with the same current. One problem is, however, that deviations in the width and size of an air gap of the brake, particularly the annular air gap, which inevitably results from manufacturing tolerances that are so great that all brakes used in a machine must be adjusted to a uniform torque or be calibrated. This results in a considerable expenditure in cost and time.
Therefore, the problem on which the invention is based is to provide an electromagnetic hysteresis brake of the above mentioned kind, in which it is possible to obtain an adjustment in relation to a uniform torque by means of simple steps.
According to the invention, this problem is solved by the steps mentioned in the characteristic part of claim 1.
In solving said problem, the inventor takes as a point of departure the knowledge that the size of the air gap reflects upon the characteristic line of the path of the torque. The larger the air gap is, for example, the smaller the torque becomes.
However, as already mentioned, air gaps of different sizes cannot be avoided.
By the fact that an adjustable air gap has now been "artificially" provided, it is finally possible by adequately changing said adjustable air gap to obtain that the sum of all the air gaps of a hysteresis brake are kept equal, it is thereby possible to provide a precisely defined or preselected torque for a hysteresis brake.
For this purpose, it is only required that after producing a hysteresis brake of the above mentioned kind, a calibrating current is adjusted and then that the adjusted air gap is changed from a minimum to a maximum until reaching the desired torque.
In a simple manner, an air gap will be adjustably designed between the inner and outer pole ring parts for which specially recommends itself the air gap between the outer pole ring part, which cup-like comprises the inner pole ring part, and a front side of the inner pole ring part.
For a precise adjustment of the air gap, the gap size will be advantageously designed wedge shaped that becomes larger toward the axis of rotation.
The wedge shape between the inner and outer pole ring parts can be produced in different manners.
It is thus possible, for example, to situate in this place between both pole ring parts a disc designed in the shape of a cup spring which is elastically deformable and by means of which the space or air gap between the inner and outer pole ring parts is adjusted in this manner.
Alternatively to this, either the outer pole ring part can have a wedge shape, on the side coordinated with the inner pole ring part, in which case the outer pole ring part must be elastically deformable in this area or the inner pole ring part have-in reversal of that-a corresponding wedge, cup or hollow shape on the front side coordinated with the outer pole ring part.
The size of the air gap can be changed in different manners. For this purpose, a fixing bolt, for example, by means of which the air gap can be adjusted so as to adequately change the space between the inner and outer pole ring parts can be provided in a simple manner.
In a structural embodiment, it can be provided for said purpose that the back of the outer pole ring part is provided with a central hole through which the fixing bolt can be inserted and threaded in the inner pole ring part.
By intentionally leaving a residual air gap, that is, an incomplete tightening of
REFERENCES:
patent: 3626220 (1971-12-01), Niculescu
patent: 4216849 (1980-08-01), Neill
patent: 4235311 (1980-11-01), Brinkmann et al.
patent: 4337855 (1982-07-01), Bennett
patent: 4515251 (1985-05-01), Wruk
patent: 4679745 (1987-07-01), Kim
patent: 4982825 (1991-01-01), Sekella
patent: 5497860 (1996-03-01), Hendricks
Antriebstechnik, vol. 24, No. 6, 1985 Mainz De, pp. 42-44; "Exakte Zugkraftregelung durch HystereseKupplungen unde-Bremsen", see p. 42; figure 2B.
Lipka Pamela J.
Oberleitner Robert J.
ZF Friedrichshafen AG
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