Contact brush holder

Abstract

A contact brush holder is disclosed. According to an aspect, a brush holder is provided for receiving at least two contact brushes and holding the brushes in contact with a slip ring in an electrical power device. The brush holder comprises a holder body adapted for receiving said brushes. The brushes are arranged on opposite sides of a plane in which a central axis of the brush holder is located and in which an axis of rotation of the electric apparatus is situated. A biasing device is provided for biasing the holder body towards the slip ring, thus biasing the at least two contact brushes towards the slip ring.

Claims

1. A brush holder for receiving at least two contact brushes and holding said brushes in contact with a slip ring in an electrical power device, the brush holder comprising: a holder body adapted for receiving and retaining said brushes, said brushes being arranged on opposite sides of a plane in which a central axis of the brush holder is located, said brushes are substantially arranged and retained, evenly and symmetrically, on each side of the holder body, around the circumference of the slip ring; a first and second portion of the holder body, wherein the first and second portion are arranged at an angle to a plane in which the central axis of the holder body is located; a single main biasing device for biasing said brushes and for providing an even contact pressure, via a pressure plate, using a pressure finger arrangement on said brushes towards the slip ring, thus biasing said brushes towards the slip ring simultaneously; a tilting device arranged in connection to the pressure plate such that the tilting device pivots about an axis of rotation that is parallel to the axis of rotation of the slip ring, wherein the pressure finger arrangement is arranged to engage the tilting device; and an individual compensation component for each contact brush being provided at an angle relative to the center axis of rotation of the electric apparatus and between at least one of said brushes and the single main biasing device, wherein said compensation component comprises a spring having a higher spring force than the single main biasing device, the spring being arranged on the side of the tilting device which is distal to the holder body, wherein the single main biasing device engages each brush simultaneously and pivots at an axis that is orthogonal to the center axis of the electric apparatus and extends in a substantially radial direction of the slip ring.

2. The brush holder according to claim 1, wherein the single main biasing device is moveable between the holder body and a mounting part.

3. The brush holder according to claim 1, wherein the single main biasing device is arranged to provide a biasing force along a substantially radial direction of the slip ring.

4. The brush holder according to claim 1, wherein the brushes are substantially symmetrically arranged about the plane, in which the radial direction is located, and in which the rotation axis of the slip ring is located.

5. The brush holder according to claim 1, wherein said pressure finger arrangement is provided with said compensation components.

6. The brush holder according to claim 1, wherein the holder body is a substantially rigid body having pockets for holding at least two brushes.

7. A brush unit comprising a brush holder according to claim 1 and at least two brushes.

8. An electric power device comprising the brush unit as claimed in claim 7; the tilting device according to claim 1, and the slip ring according to claim 1, whereby the single main biasing device of the brush unit is arranged to provide an even contact pressure, via the pressure plate according to claim 1, using the pressure finger arrangement, according to claim 1, on the at least two brushes against the slip ring simultaneously, and wherein compensation component are provided between at least one of said brushes and the holder body, and wherein said compensation component comprises a spring having a higher spring force than the single main biasing device, and wherein the tilting device is connected to the pressure plate such that the tilting device pivots about an axis of rotation that is parallel to the axis of rotation of the slip ring, wherein the pressure finger arrangement is arranged to engage the tilting device.

9. A wind power unit comprising a brush holder according to claim 1 and the slip ring.

10. A method of biasing a contact brush towards a slip ring in an electric power device, comprising: providing a brush holder body holding at least two contact brushes, the at least two contact brushes being arranged on opposite sides of a plane in which a central axis of the brush holder is located, wherein said at least two contact brushes are substantially arranged and retained evenly and symmetrically, on each side of the holder body, around the circumference of the slip ring; providing a first and second portion of the holder body, wherein the first and second portion are arranged at an angle to a plane in which the central axis of the brush holder body is located; providing a single main biasing device for providing an even contact pressure, via a pressure plate, using a pressure finger arrangement on the at least two contact brushes against the slip ring; providing a tilting device arranged in connection to the pressure plate such that the tilting device pivots about an axis of rotation that is parallel to the axis of rotation of the slip ring, wherein the pressure finger arrangement is arranged to engage the tilting device; biasing, using the single main biasing device, the at least two contact brushes towards the slip ring, such that the at least two contact brushes are biased towards the slip ring simultaneously; and providing individual compensation component for each of the contact brushes and the holder body, arranged between the at least two contact brushes and the single main biasing device, wherein said individual compensation component comprise a spring having a higher spring force than the single main biasing device, the spring being arranged on the side of the tilting device which is distal to the holder body, wherein the single main biasing device engages each brush simultaneously and pivots at an axis that is orthogonal to the center axis of the electric apparatus and extends in a substantially radial direction of the slip ring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present solution will now be described, by way of example, with reference to the accompanying schematic drawings.

(2) FIG. 1 is a schematic perspective view of a brush holder according to prior art.

(3) FIG. 2 is a schematic perspective view of a brush holder according to the present disclosure.

(4) FIG. 3 is a schematic side view of a brush holder according to the present disclosure.

(5) FIG. 4 is a schematic front view of a brush holder according to the present disclosure.

(6) FIG. 5 is a schematic perspective view of a brush holder according to one embodiment of the present disclosure.

(7) FIG. 6 is a schematic perspective view of a system with a brush holder and a slip ring.

(8) FIG. 7 is a schematic view of generator provided with brush holders according to one embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

(9) In the below description the term brush should be interpreted as a contact or electrical carbon brush.

(10) FIG. 1 illustrates a brush holder according to prior art. Each contact brush is provided with an individual biasing means to maintain the pressure of the brush towards the slip ring.

(11) FIG. 2 illustrates a brush holder 1 according to the present disclosure. The brush holder 1 is provided with a holder body 10 which is adapted to receive and hold electrical contact brushes, the holder body 10 and/or any brushes arranged therein may be connected to or engage a biasing device 11. The holder body 10 may be provided with pockets, 7, 8, adapted for receiving and holding one, two, three, or more electrical contact brushes 2,4. The brushes 2,4, as arranged in the pockets 7,8, may be connected to a force or pressure plate 15. The pressure plate 15 may be connected to or be a part of the biasing device 11.

(12) The biasing device 11 may comprise a spring 3, such as a socket spring arrangement 14 which is shown in FIGS. 2-4 or according to an alternative embodiment a pneumatic or hydraulic cylinder 9, which is shown in FIG. 5. The spring or biasing device may be any type of spring arrangement, such as a helical or blade spring. The main function of the spring or biasing device os to provide an even contact pressure or tension towards or against the slip ring during the entire cycle of use and wear.

(13) The brushes may be so called carbon brushes which are well known in the art. Any types of electrical contact brushes may be arranged in the holder, such as silver or cupper graphite brushes, and they may be of any conventional type such as carbon brushes, strip or laminate, strip and wire or folded mesh or gauze brushes.

(14) As shown in FIGS. 2-5 there is only one biasing device 11, thus forming a main spring arrangement, arranged to provide the required pressure to all the brushes 2, 2, 2, 4 arranged in the holder body 10 simultaneously, such that the brushes may engage or contact a slip ring 20 (as shown in FIG. 6) properly.

(15) The holder 1 may be arranged in the holder body 10, such that the brushes 2, 4 may contact a slip ring 20 at the end of the brushes which is distal to the biasing device 11 (as shown in FIG. 6).

(16) In one embodiment, the force or pressure plate 15 may be arranged at one end of the spring arrangement 3, which is closest to the holder body 10. According to an alternative embodiment, the force plate may be arranged at the opposite end, i.e. at the end or mounting portion 16 of the spring that is distal to the holder body.

(17) According to one embodiment, the brushes 2, 4 are arranged around a central axis C-C, i.e. arranged om opposite sides of a plane in which a central axis C of the brush holder 1 is located as shown in FIGS. 2 and 3. According to this embodiment the holder body 10 may comprise a first 10a and a second 10b portion as seen in a plane parallel to the central axis C-C.

(18) According to one embodiment the brushes may be arranged evenly or symmetrically around the central axis. This means that the holder body 10 and its pockets 7, 8 are arranged such that if the holder is to retain four brushes these are arranged such that the first and second brushes 2, 2 are placed on one side or in the first portion 10a, and the third and fourth brushes 4, 4 are placed opposite to the first and second brushes or in the second portion 10b. Further, as shown in FIGS. 2-5, if the holder is adapted to retain six brushes the first three 2, 2, 2 are placed on one side of the central axis and the last three 4, are placed on the opposite side.

(19) According to an alternative embodiment the number of brushes arranged on each side of the axis of rotation or central axis C-C is an uneven number. However the total surface area of the brushes that engages the slip ring is equal or symmetrical on both sides. That means that for example two brushes having a surface area of 4 cm.sup.2 may be arranged on one side (or in the first portion 10a of the holder body) of the central axis and one brush having a surface area of 8 cm.sup.2 may be arranged on the opposite side (or in the second portion 10b of the holder body).

(20) Other types of arrangements of the brushes are also conceivable, but are not shown in the figures.

(21) The holder body 10 and/or the pockets 7, 8 may be sized and adapted to accommodate brushes of different sizes and shapes. The holder body 10 may further be adapted or constructed to retain virtually any number of brushes, but is preferably adapted to retain between 2 and 16 brushes.

(22) According to a preferred embodiment the holder is adapted to retain between 2 and 8 brushes arranged evenly and symmetrically around the central axis C-C.

(23) FIG. 4 illustrates one embodiment in which the brushes 2,4 may be connected to the force or pressure plate 15 through so called force or pressure fingers 12, 17, i.e. one pressure finger 12, 12, 12, 17, 17, 17 is arranged to engage each brush 2, 2, 2, 4, (4, 4 not shown in the figures) being arranged in the pockets 7, 7, 7, 8, 8 8. The pressure finger may according to one embodiment be arranged to push down on the brush without being fixedly connected to the brush (not shown). According to an alternative embodiment the pressure finger is fixedly or hingedly connected to the brush and/or the brush holder body or pocket.

(24) The force or pressure plate 15 may, according to one embodiment, be connected to the biasing device 11 such that the biasing device is able to act on all the brushes arranged in the holder body simultaneously. This means that instead of having a biasing device 11 for each brush as shown in the prior art holder of FIG. 1, there is instead one common or main biasing device that provides the required pressure for all the brushes arranged in the holder 1.

(25) According to one embodiment, the holder body 10 may be arranged such that the first 10a and second 10b portions of the holder body the or pockets 7, 8, are arranged at an angle, which may be <90 degrees, to a plane in which the central axis C-C lies. This means that the brushes may be arranged at an angle to the central axis C-C of the holder. As shown in FIG. 5 the brush holder thus forms a V shape, where the brushes are arranged along the legs of the V and where the legs of the V crosses such that an imaginary bottom end of the V may be aligned with the centre of or axis of rotation of a slip ring (not shown in the figure), and thus the carbon brushes may be arranged to tangent the centre of the slip ring. This also means that the first 10a and second 10b portions of the holder body may be arranged to allow for the brushes 2,4 thus to contact or engage the slip ring at two different locations. The diameter of the slip ring determines the optimal angle.

(26) According to an alternative embodiment the angle of the V shape may be adapted for different types of brushes, and the angle may be such that the legs of the V cross and thus imaginary bottom end of the V may be arranged at any other locations than the centre of the slip ring.

(27) According to one embodiment the pressure fingers 12 may be arranged to engage a tilting device 13, which device 13 may be arranged in connection with the pressure plate 15. According this embodiment the tilting device 13 may be connected to the pressure plate such that it is pivotable, i.e. able to pivot, about an axis of rotation R-R. By this arrangement it is possible to arrange the pressure finger arrangement at an angle in relation to the central axis of the holder. This may be done to further be able compensate for any pressure losses that may occur when the holder body is arranged at an angle to the central axis, i.e. is in a V shape. The rotation or tilting of the pressure finger arrangement 12 may thus be adjusted to correspond to or be adjustable to the angle at which the first 10a and second 10b portions of the holder body are arranged. This means that when the biasing device 11 is operated to push the carbon brushes towards the surface of the slip ring the pressure fingers are able to tilt or pivot about the axis of rotation R-R at a degree that is optimal to provide for the proper compensation for pressure losses. The changes in spring force when the biasing device 11 when it changes during the operation distance, can be calculated through the spring constant. This may therefore be compensated by the force finger being able to tilt or pivot about the axis of rotation R-R in relation to the brush, such that a contant and even pressure may be applied to the brushes towards the slip ring. Through this arrangement also the decreasing weight of the brush, due to the wear, can be compensated for, depending on the location of the brush in relation to the centre of the slip ring. According to yet an alternative each pressure finger is arranged to be able to pivot independently of the other pressure fingers (not shown).

(28) According to an alternative embodiment the pressure fingers my be fixedly connected to the pressure plate, thus having a constant angle in relation to the central axis C-C.

(29) The connection of the pressure fingers 12 to the tilting device 13 may be accomplished with conventional means such as a nut and bolt arrangement 19. The pressure fingers may according to alternative embodiment be welded to the tilting device 13 and/or pressure plate 15 or be connected or fixated by any other suitable means.

(30) Each pressure finger 12, 12, 12 may be provided with individual compensation means 5, 5, 5 in order to minimize vibrations and thus even further optimize the pressure distribution from the biasing device 11. The compensation means 5 may according to one embodiment be arranged at the side of the tilting device 13 which is closest to the holder body 10, shown in FIG. 4, and may thus be arranged between the brush and the holder body. The compensation means 5 may also be arranged, which can been seen in FIG. 4, between the biasing device 11 (or the tilting device 13) and the contact brush 2. The compensation means 5, 6 may be a spring having a higher spring force or spring pressure than the biasing device 11 or main spring. This means that the sum of forces that the compensation means exert on each contact brush is higher than the force exerted by the single biasing device or main spring. For example, if the biasing device exert a force of 10 N, the sum of the force exerted by the compensation means, i.e. the total force exerted by the compensation means is greater than 10 N.

(31) According to one alternative embodiment the compensation means may be tension spring arranged on the side of the tilting device which is distal to the holder body 10 (not shown).

(32) According to yet an alternative the pressure finger arrangement 12 may be arranged to constitute the compensation means e.g. by being a spring blade, a leaf blade or a laminated type spring (not shown).

(33) FIGS. 2-4 illustrate that the biasing device 11 may comprise a spring arrangement 3 such as a socket spring 14. This arrangement may be provided with a mounting part 16 at the end of the spring arrangement that is distal to the holder body. The mounting part 16 may also provide for a connection to a control system or for the connection to an electrical system in which the holder is arranged.

(34) The biasing device 11 may be operable, or moveable between the holder body 10 and the mounting part 16 and substantially in a direction along the central axis C-C of the holder 1. The biasing device 11 may be arranged to provide a biasing force along a substantially radial direction of the slip ring which means that the biasing device may be arranged to push the brushes towards the slip ring simultaneously. This means that an external pressure source is arranged to influence the biasing device 11, which then pushes the brushes towards the slip ring with a pressure suitable to provide an optimal contact between the slip ring or connector and the carbon or contact brushes. By biasing device is thus meant a contact pressure providing arrangement.

(35) FIG. 5 illustrates a holder 1 in which the biasing device 11 comprises a pneumatic or hydraulic cylinder 9. By such an arrangement, the pressure provided may be even further optimized and controlled.

(36) FIG. 6 illustrates a system 25 with a brush holder 1, holding six brushes adapted to be able to engage a slip ring 20. As shown in FIG. 6 the brush holder is arranged in a V shape, such that the receiving portions tangent the centre of the slip ring for an optimal contact surface of the contact brushes against the slip ring 20.

(37) In order to provide for an optimal or maximal flexibility in the system the angle of the first 10a and second 10b portions or pockets 7,8 in relation to the slip ring and the size of the bushes is important. The combination of the force finger arrangement 12, 17 being able to pivot about an axis of rotation combined with the compensation means 5, 6 may thus provide for the possibility of having different diameters of the slip ring 20 and different sizes of the brushes 2,4 and may thus provide for a desired flexibility and ability of the system to compensate for differences in pressure or tension of the brushes towards the slip ring, that may occur due to the density of the brushes, the design of the slip ring and other, both internal and external, influences.

(38) The present holder may further provide for an advantage in that the cables 21, 21, 21 connecting the brushes 2, 4 to the brush holder body 10 may be prevented from falling onto the slip ring arrangement in that the holder 1 may be arranged at a 90 degree angle, i.e. perpendicular, to the arrangement shown in FIG. 6. This type of arrangement of the holder is further advantageous in that it may no longer be necessary to take the weight of carbon brushes and thus its effect on the spring force into account.

(39) FIG. 7 illustrates brush holders 1, 1, 1 and slip ring systems 25, 25, 25 arranged in parallel in a generator 30. The generator 30 may be any conventional type of generation placed in a wind power plant, a ship or any other type of electrical power unit that requires a rotary electrical connection.

(40) According to one embodiment the pressure to the biasing device may be provided from an external source such as a compressor or a fixedly mounted spring arrangement.

(41) The holder may according to one embodiment, not shown in the figures, be provided with equipment for measuring temperature of the brushes and equipment for measuring the wear of the brushes, measurements that can be transmitted to a computer or some type of warning system. This is especially advantageous when the holder is incorporated into a system which cannot easily be regularly manually checked, such a remotely located wind power plant.

(42) The holder may be machined or moulded and it may be made from a composite or metal material.

(43) The holder may be adapted to different sizes and needs depending on the material of the brush, the diameter of the slip ring and the requested transmission of energy.