ELECTROMAGNETIC BRAKE OR CLUTCH

Abstract

The disclosure relates to an electromagnetic brake or clutch having an electromagnet, a permanent magnet and an armature plate interacting with the electromagnet and the permanent magnet, which armature plate is arranged on a hub body so as to be non-rotatable but nevertheless axially displaceable, the electromagnet having a magnet housing and a coil received therein, wherein the magnet housing has, on the armature plate side, an outer ring body providing an external pole and an inner ring body providing an internal pole, characterized in that the inner ring body carries the permanent magnet on the armature plate side and that a web which serves as magnetic flux bridge and connects the inner ring body to the outer ring body is disposed between the inner ring body and the outer ring body.

Claims

1. An electromagnetic brake or clutch having an electromagnet, a permanent magnet and an armature plate interacting with the electromagnet and the permanent magnet, which armature plate is arranged on a hub body so as to be non-rotatable but nevertheless axially displaceable, the electromagnet having a magnet housing and a coil received therein, wherein the magnet housing has, on the armature plate side, an outer ring body providing an external pole and an inner ring body providing an internal pole, wherein the inner ring body carries the permanent magnet on the armature plate side and that a web which serves as magnetic flux bridge and connects the inner ring body to the outer ring body is disposed between the inner ring body and the outer ring body, whereby the outer ring body projects axially beyond the inner ring body towards the armature plate.

2. The electromagnetic brake or clutch according to claim 1, wherein the inner ring body, the outer ring body and the web are formed as one piece.

3. The electromagnetic brake or clutch according to claim 1, wherein the magnet housing comprises a magnet pot which provides the inner ring body, the outer ring body and the web on the armature plate side.

4. The electromagnetic brake or clutch according to claim 1, wherein the magnet pot is formed of a soft-magnetic material.

5. The electromagnetic brake or clutch according to claim 1, wherein the magnet pot is of closed design on the armature plate side.

6. (canceled)

7. The electromagnetic brake or clutch according to claim 1, wherein the permanent magnet carried by the inner ring body terminates flush with the outer ring body on the armature plate side.

8. The electromagnetic brake or clutch according to claim 1, wherein the permanent magnet and/or the outer ring body provides a friction surface interacting with the armature plate on the armature plate side.

9. The electromagnetic brake or clutch according to claim 1, wherein the friction surface is provided by a friction facing applied to the permanent magnet and/or the outer ring body.

10. The electromagnetic brake or clutch according to claim 1, wherein the permanent magnet is provided by a ring body whose axial dimension is smaller than its cross-sectional thickness between its inner diameter and its outer diameter.

Description

DRAWINGS

[0020] Further advantages and features of the disclosure will become apparent from the following description with reference to the drawings.

[0021] FIG. 1 shows in a schematic perspective view a design according to the disclosure using the example of an electromagnetic brake;

[0022] FIG. 2 shows in a schematic exploded view the electromagnetic brake according to FIG. 1;

[0023] FIG. 3 shows in a partial sectional view the electromagnetic brake according to FIGS. 1 and 2;

[0024] FIG. 4 shows in a schematic representation an and attraction process with the armature plate opened and the coil de-energized;

[0025] FIG. 5 shows in a schematic representation a brake/stop operation with the armature plate closed and the coil de-energized; and

[0026] FIG. 6 shows in a schematic representation a release operation with the armature plate closed and the coil energized.

[0027] The design according to the disclosure is shown in FIG. 1 using the example of an electromagnetic brake 1.

DETAILED DESCRIPTION

[0028] The electromagnetic brake 1 comprises in the manner known per se an electromagnet 2, a permanent magnet 3 and an armature plate 4 that interacts with the electromagnet 2 and the permanent magnet 3. The armature plate 4 is also arranged in a manner known per se on a hub body 11 so as to be fixed against rotation, but nevertheless axially displaceable. The hub body 11 can in turn be mounted in a manner not further shown in the Figures.

[0029] For the purpose of a non-rotating, yet axially displaceable arrangement of the armature plate 4 on the hub body 11, the armature plate 4 is fastened to the hub body 11 with the interposition of a spring element 12. The spring element 12 is arranged on the armature plate 4 by means of rivets 13 and is detachably connected to the hub body 11 by means of screws 14.

[0030] The electromagnet 2 has a magnet housing 5 and a coil 6 received by it. The magnet housing 5 is designed in two parts and has a magnet pot 9 on the one hand and a flange 8 on the other hand, which is preferably screwed to it in the final assembled state. A cable connection 7 is provided to supply the coil 6 with power.

[0031] On the hub body side, the magnetic pot 9 is equipped with a circumferential groove into which an annular wiper 10 is inserted in the final assembled state.

[0032] The structure of the electromagnetic brake 1 according to the disclosure, as explained above, results in particular from a synopsis of FIGS. 1 and 2.

[0033] A synopsis of FIG. 1 with FIG. 3 in particular also shows that the magnet housing 5, and specifically the magnet pot 9, has an outer ring body 15 providing an external pole and an inner ring body 16 providing an internal pole on the armature plate side. In accordance with the disclosure, a web 17 connecting the inner ring body 16 to the outer ring body 15 is arranged between the inner ring body 16 and the outer ring body 15. This web 17 serves as a magnetic flux bridge between the two poles, i.e. the external pole provided by the outer ring body 15 on the one hand and the internal pole provided by the inner ring body 16 on the other hand.

[0034] According to the disclosure, it is also provided that the inner ring body 16 carries the permanent magnet 3 on the armature plate side. The permanent magnet 3 is provided by a ring body which is aligned parallel to the armature plate 4 with regard to its large sides and can also be formed in several parts if necessary. The axial dimension of the permanent magnet 3 is thus smaller than its cross-sectional thickness between its inside diameter and its outside diameter.

[0035] Due to the web 17 provided between the outer ring body 15 and the inner ring body 16 according to the disclosure, the magnetic resistance between the two magnetic poles of the permanent magnet 3 is minimized. In contrast to the designs known from prior art, no secondary air gap is formed between the ring bodies, which leads to a reduction in the magnetic resistance. As a result, the efficiency of the coil 6 can be increased. Furthermore, since no undesirable magnetic shunts are built up in the housing, there is a reduced use of magnetic material and thus a reduction in costs. Preferably, the magnetic pot 9 is made of a soft-magnetic material.

[0036] FIG. 3 also shows the magnetic flux of the permanent magnet 3 by means of the arrows 18 and 19, namely on the one hand the magnetic flux 18 via the web 17 and on the other hand the magnetic flux 19 via the magnet housing 5. FIG. 3 shows the armature plate 4 in the open position with the coil 6 not energized.

[0037] FIG. 4 also schematically shows the magnetic flux when the armature plate 4 is open and the coil 6 is not energized. The magnetic flux is also shown in correspondence with the arrows 18 and 19.

[0038] FIG. 5 shows a schematic representation of a braking or stopping operation, according to which the armature plate 4 is closed and the coil 6 is not energized. Here, too, the magnetic flux is established in accordance with arrows 18 and 19, whereby the proportion of the direct magnetic flux 18 via the web 17 is increased compared to the open position of the armature plate 4 according to FIG. 4, which is symbolized by the line thickness of arrow 18.

[0039] As can be seen from a synopsis of FIG. 4 with FIG. 5, a direct, short and parallel long magnetic circuit with low resistance is established. The portion of the direct magnetic flux over the web is determined by the web thickness. Due to the design, 80% of the torque is applied to the external pole, for example, which facilitates heat dissipation. Furthermore, a more efficient use of the permanent magnet can be achieved, as can be seen in particular in the illustration according to FIG. 5.

[0040] Finally, FIG. 6 shows the situation as it occurs when the armature plate 4 is closed and the coil 6 is energized. This results not only in magnetic fluxes 18 and 19 due to the permanent magnet 3, but also in magnetic fluxes 20 and 21 due to the electromagnet 2. In correspondence with the arrows 20 and 21, a magnetic flux 21 occurs both via the magnet housing 5 and a magnetic flux 20 via the web 17. FIG. 6 specifically shows the releasing process, whereby an opposite polarity of the coil and permanent magnet circuit is established in the pole faces and in the long magnetic circuit, and an equal polarity is established in the short magnetic circuit.