JPH10257722A - Collector ring device of retaining electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage to the surface of a collector ring and the occurrence of spark, and the abnormal abrasion of a brush, by providing a magnet on the brush of the collector ring. SOLUTION: For example, a brush 9a in one retainer, and a permanent magnet 22 thereon, are inserted, and a brush 10a in the other retainer, and a permanent magnet 23 thereon, are inserted. What is more, the brushes 9a and 10a are made of metallic graphitic brushes. By the permanent magnet 22(23), a magnetic circuit of a permanent magnet 22(23) → a brush 9a(10a) →a collector ring 2 →a permanent magnet 22(23) is made as shown by an arrow 24, and magnetic force works on the contact face between the collector ring 2 and the brush 9a(10a) so as to accelerate the adsorption of oxygen, and an oxide film is made on the surface of the brush 9a(10a). Thus, the oxide film can be made on the surface of the brush 9a(10a) even in a low current density region, so this can prevent the brushes 91 and 10a from being abraded abnormally, damaging the surface of the collector ring 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current collecting ring device for a rotating electric machine, which is a wound three-phase induction motor.

[0002]

2. Description of the Related Art FIGS.
Shown in In the drawing, reference numeral 1 denotes a rotating shaft of a rotary electric machine which is a winding type three-phase induction motor, on which a current collecting ring 2 for three phases is fitted and fixed to a current collecting cylinder (not shown) with a barrier 3 interposed therebetween. The current collector 4 is mounted by shrink fitting. Reference numeral 5 denotes three brush holders respectively corresponding to the current collecting rings 2 for the three phases, which are fixed to a fixed frame 7 by stats 8 so that insulators 6 alternately exist.

In each of the brush holders 5, two types of brushes, that is, a first brush 9 and a second brush 10, are held by two holding portions 5a and 5b having a rectangular cylindrical shape so as to be movable in the vertical direction. Have been. These brushes 9 and 10 are fixed pressure springs 11 mounted on the upper portions of the holding portions 5a and 5b.
12 and is brought into contact with the central portion of the corresponding current collecting ring 2 at an appropriate pressure.

A secondary lead wire 14 of each phase derived from the secondary winding of the wound three-phase induction motor is connected to a connection terminal 15 corresponding to each current collector ring 2 of the current collector 4, and a brush is provided. The connection terminals 9 and 10 are connected to connection terminals 18 and 19 of the brush holder 5 via picktel wires 16 and 17, and the connection terminal 20 connected to the connection terminals 18 and 19 is connected via a lead wire 21 to an external resistor ( (Not shown).

In a wound type three-phase induction motor of this type, an external resistor is connected to the secondary side via a collector ring device to increase the starting torque and at the same time limit the starting current. . In this case, the temperature of the brushes 9 and 10 which are in sliding contact with the current collecting ring 2 of the current collecting ring device varies depending on the specifications at the time of manufacturing the induction motor, the increase / decrease of the capacity, the use environment, the use condition, and the like. In order to bring the brushes 9 and 10 into sliding contact with the current collecting ring 2 stably,
It is necessary to form a stable oxide film on the surface of the current collector ring 2, and the brushes 9 and 10 need to be in an appropriate temperature range for forming the oxide film.

[0006]

In general, when manufacturing an induction motor, the materials of the brushes 9 and 10 of the current collecting ring device are selected assuming a 100% load. Changes in operating conditions. In addition, since a production request is made from the beginning so as to have a margin with respect to the load of the counterpart machine, the operation is often performed with a light load. As described above, when the operation becomes light load, the current density of the brushes of the current collecting ring device decreases, and the temperature of the brushes 9 and 10 decreases. An oxide film is less likely to be generated on the surface of the electric ring 2.

If the oxide film is not smoothly formed on the surface of the current collecting ring 2, the brushes 9 and 10 will directly contact the metal (copper) surface of the current collecting ring 2 so that the surface of the current collecting ring 2 Failures such as scratching or abnormal wear of the brushes 9 and 10 occur. In order to eliminate such inconvenience as much as possible, conventionally, the materials of the brushes 9 and 10 are changed according to the load. Conventionally, an electric graphite brush is used for the brushes 9 and 10.

[0008] However, although the electric graphite brush has excellent lubrication performance in terms of sliding contact characteristics, there is a problem that when the current density increases, the temperature rises sharply and sparks are generated.
In addition, the metallic graphite brush easily forms an oxide film in a high current density region, and the surface of the current collector ring 2 becomes smooth to show good sliding contact characteristics. There is a problem that the surface of the current collecting ring 2 is damaged without being able to do so.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to always adapt to the use conditions, and to prevent damage to the surface of a current collecting ring, generation of sparks, and abnormal wear of a brush. The present invention provides a current collector ring device for a rotating electric machine that can perform the above operation.

[0010]

According to the present invention, there is provided a current collecting ring device for a rotating electric machine, comprising: a brush holder having a holding portion at a distal end fixed to a fixed frame by a stud; a brush holder housed in the holding portion; In the current collector ring device of a rotating electric machine having a current collector ring forming a part of a current collector fitted to the brush, which slides on the lower end face of the brush and slides on the lower end surface of the brush, A magnet is provided above the brush.

With this configuration, as described later,
With respect to metal wear, magnetic fields are known to promote the transition from severe wear to mild wear, which promotes the adsorption and oxidation of oxygen on the brush and creates an oxide film. Therefore, it is possible to always adapt to the use conditions, and it is possible to prevent damage to the current collecting ring, generation of sparks, and abnormal wear of the brush.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. The same components as those in the related art are denoted by the same reference numerals, and detailed description thereof is omitted.

The brush 9a and its upper portion are provided in the holding portions 5a and 5b of the brush holder 5 of the current collecting ring portion of the conventional rotary electric machine shown in FIG. The permanent magnet 22 is inserted into the holder 5b, and the brush 10a is
Then, the permanent magnet 23 is inserted in the upper part. In addition, brush 9
The materials a and 10a are metallic graphite brushes.

In the current collecting ring constructed as described above, the magnets 24 of the permanent magnets 22 and 23 indicate arrows 2 in FIG.
4, the magnet 22 (23) → the brush 9a (10
a) → the current collector ring 2 → the magnetic circuit of the magnet 22 (23) is formed, and the magnetic force acts on the contact surface between the current collector ring 2 and the brushes 9a, 10a to promote the adsorption of oxygen, so that the brushes 9a, 1
An oxide film is formed on the surface of Oa. As a result, an oxide film can be formed on the surfaces of the brushes 9a and 10a even in a low current density region, so that the surface of the current collector ring 2 is damaged and the brushes 9a and 1a are damaged.
0a can be prevented from being abnormally worn. Metallic graphite brushes have low specific resistance and low contact resistance, so they have a low contact voltage drop and a low temperature rise, and can be used up to a high current density region. Can also be prevented.

More specifically, a transition metal having a vacancy in the electron orbit or a ferromagnetic material containing a transition metal as a main component, for example, a steel material, is in a chemically non-equilibrium state and is easily bonded to other elements. When magnetism is applied to the sliding member made of such a material, the action of bonding (ionic bond or covalent bond) with another element is activated, and the adsorption of oxygen is promoted to form an oxide film. When this oxide film is interposed on the friction surface, contact and adhesion between the new surfaces are reduced, and the wear powder is pulverized to produce mild wear powder at an early stage.

Further, the magnetic field holds the mild wear powder on the friction surface by its attraction, and the mild wear powder is deposited on the friction surface. This forms a mild wear surface on the friction surface and reduces wear on the contact surface. FIG. 4 illustrates this, in which the sliding body B in (a) corresponds to the current collecting ring 2 and the sliding body C corresponds to the brushes 9a and 10a. Also, the states of the contact surfaces are represented by (b) without magnetism and (c) with magnetism, respectively.

In summary, (1) the magnetic field creates mild wear powder from the beginning of friction. (2) The magnetic field does not allow the mild wear powder to escape from the friction surface and facilitates the generation of the mild wear surface.

These two effects promote the transition from severe wear to mild wear, and the transition to mild wear reduces wear on the friction surface. This mechanism is described in Volume 3 and Issue 6 of "Tribologist" (19
89), pages 430-436.

Next, the second embodiment will be described with reference to FIG. 2. By providing yokes 25 and 26 for guiding the magnetism 24 by the magnets 22 and 23, the contact surface between the current collecting ring 2 and the brushes 9a and 10a is provided. The concentration of the magnetism 24 can improve the formation of the oxide film.

Next, a third embodiment will be described with reference to FIG. 3. The brushes 9a and 10a are made of metal graphite brushes, and permanent magnets 22a and 23 are provided on both sides of the brushes 9a and 10a.
a, the magnet 24 is connected to the current collector ring 2 and the brush 9.
a, 10a. Thus, an oxide film is formed on the contact surface, and can be applied from a low current density region to a high current density region.

It should be noted that the present invention is not limited to the above-described and illustrated embodiments. For example, the present invention is applicable not only to a wound three-phase induction motor but also to any rotating machine requiring a current collecting ring device. Of course, various changes can be made without departing from the scope of the invention.

[0022]

As described above, according to the present invention, it is possible to always adapt to the conditions of use, and it is possible to prevent damage to the surface of the current collector ring, generation of sparks and abnormal wear of the brush. Is played.

[Brief description of the drawings]

FIG. 1 is a magnet layout diagram of a current collecting ring device showing one embodiment of the present invention,

FIG. 2 is a diagram corresponding to FIG. 2, showing another embodiment of the present invention;

FIG. 3 is a diagram corresponding to FIG. 2, showing another embodiment of the present invention;

FIG. 4 is an explanatory diagram of an operation,

FIG. 5 is a front view of a conventional current collecting ring device,

FIG. 6 is a side view showing a partial cross section of a conventional current collecting ring device.

[Explanation of symbols]

1 ... rotating shaft, 2 ... current collector ring, 4 ... current collector, 5 ... brush holder, 7 ... fixed frame,
8… Stat, 9,9a, 10,10a… Brush. 11,12 ... constant pressure spring, 16,17 ... pick tail wire, 22,23 ... permanent magnet,
25,26… yoke.

Claims (3)

[Claims] 1. A brush holder having a holding portion at a tip fixed to a fixed frame by a stud, a brush housed in the holding portion and having a picktel wire pressed by a spring, and a lower end surface of the brush. In a current collector ring device for a rotating electric machine having a current collecting ring slidably forming a part of a current collector fitted to a rotating shaft, a magnet is provided on an upper portion of the brush, wherein the magnet is provided. Electric ring device. 2. The current collector ring device for a rotating electric machine according to claim 1, wherein a yoke for inducing magnetism is provided around the brush on which the magnet is mounted. 3. The current collector ring device for a rotating electric machine according to claim 1, wherein magnets are provided on both sides of said brush.