JPH0626461B2 - Current collector for rotating electric machine - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a current collecting ring device for a rotary electric machine such as a winding type three-phase induction motor.

[Technical background of the invention and its problems]

In a rotating electric machine, for example, a winding type three-phase induction motor, an external resistor is connected to the secondary side through 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 brush slidably contacting the current collecting ring of the current collecting ring device changes depending on the specifications at the time of manufacturing the induction motor, increase / decrease in capacity, use environment, change in use conditions and the like. In order to make the brush slidably contact the current collecting ring, it is necessary to form a stable oxide film on the surface of the current collecting ring. To form the oxide film, bring the brush into an appropriate temperature range. There is a need. By the way, in general, when manufacturing an induction motor, the material of the brush of the current collector is selected on the assumption of 100% load, but there are changes in the usage conditions as described above, and from the beginning, Since a manufacturing request is made so as to have a margin with respect to the load of the other party machine, in many cases, it is actually operated with a light load. In such a light load operation, the current density of the brush of the current collecting ring device is lowered and the temperature of the brush is lowered, so that the chemical reaction of oxygen with copper, which is the material of the current collecting ring, is reduced, and the current of the current collecting ring is reduced. An oxide film is less likely to be generated on the surface. If the oxide film does not smoothly form on the surface of the current collector ring, the brush will directly contact the metal (copper) surface of the current collector ring, and the surface of the current collector ring will be scratched or the brush will wear abnormally. The problem occurs.

In order to eliminate such inconvenience as much as possible, conventionally, concrete measures such as changing the material of the brush according to the load are implemented.

That is, FIG. 11 shows a first conventional example in which the metal graphite brushes 2, 3 are brought into sliding contact with the current collecting ring 1, and FIG. 12 shows the current collecting ring 4 with the electric graphite brushes 5, 6. A second conventional example in which sliding contact is made is shown. In addition, 7 is a collector ring 1, 4
Is the direction of rotation. In the first conventional example using the metal graphite brushes 2 and 3, in the low current density region, the surface of the current collector ring 1 is considerably damaged and becomes uneven as shown in FIG. 13 (b). And the brushes 2 and 3 are also shown in FIG.
Abrasion loss as indicated by the amount of wear characteristics fold lines ₂ b and ₃ b of) is increased. This temperature rise characteristic polygonal line ₂ a and the temperature rise of the brushes 2 and 3 FIG. 14 (b)
_This is because the oxide film is not formed on the surface of the current collector ring 1 as shown by ₃ a. On the other hand, in the second conventional example using the electrographitic brushes 5 and 6, in the low current density region, the electrographitic brushes 5 and 6 have the ability to form an oxide film even if the temperature rise is low. the collector surface of the ring 4 as shown in Fig. 13 (a) is smooth, the temperature rise of the brushes 5 and 6 as indicated by the temperature rise characteristic fold lines ₅ a and ₆ a of the diagram the 14 (a) Compared with the metal graphite brushes 2 and 3, the wear amount of the brushes 5 and 6 is higher than that of the metal graphite brushes 2 and 3, and the wear amount characteristic broken lines ₅ b and _{6 of} FIG.
As shown by b, the amount is smaller than that of the metallic graphite brushes 2 and 3. On the other hand, in the high current density region, the second conventional example using the electrographite brushes 5 and 6 and the metal graphite brush 2,
In the first conventional example using No. 3, the surfaces of the current collecting rings 4 and 1 are smooth as shown in FIGS. 16 (a) and 16 (b).
However, the temperature rise of the electrographitic brush 5 is
As shown by the temperature rise characteristic broken line ₅ c in the figure, it becomes too large as compared with the metal graphite brush 2 shown by the temperature rise characteristic broken line ₂ c, and the oxide film formation on the surface of the current collector ring 4 becomes excessive,
The contact resistance becomes large and sparks are easily generated.

As described above, the electrographite brush has excellent lubrication performance in sliding contact characteristics, but there is a problem that the temperature rises rapidly and a spark is generated when the current density becomes high. In the high current density region, an oxide film is easily formed, and the surface of the current collector ring becomes smooth to show good sliding characteristics, but in the low current density region, the oxide film cannot be formed well and There is a problem of scratching the surface.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to always meet the usage conditions and to prevent damage to the surface of the current collector ring.
(EN) Provided is a current collector ring device for a rotating electric machine capable of preventing generation of sparks and abnormal wear of a brush.

[Outline of Invention]

In order to achieve the above-mentioned object, the present invention uses two current collector rings for each phase.
In the type of arranging brushes, the brush located on the inlet side in the rotation direction of the current collector ring is an electrographite brush and the brush located on the outlet side is a metal graphite brush, It is intended to form a stable oxide film on the surface.

Example of Invention

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

First, the overall configuration will be described with reference to FIGS. Reference numeral 11 is a rotary shaft of a winding type three-phase induction motor as a rotary electric machine, on which a current collecting ring (not shown) is fixedly fitted with current collecting rings 12 for three phases with a barrier 13 interposed therebetween. The current collector 14 is formed by shrink fitting or the like. Reference numeral 15 denotes three brush holders respectively corresponding to the current collecting rings 12 for the three phases, and these brush holders are fixed to the fixing frame 17 by the studs 18 such that the insulators 16 are alternately present. . Each of these brush holders 15 has two holding portions 15a and 15b in the shape of a rectangular tube. These holding portions 15a and 15b are two types of brushes, a first brush 19 and a second brush 20. Is held so as to be movable in the vertical direction. The brushes 19 and 20 are pressed by the constant pressure springs 21 and 22 mounted on the upper portions of the holding portions 15a and 15b to come into contact with the corresponding central portions of the current collector ring 12 at appropriate pressures. . In this case, the angle θ formed by the brushes 19 and 20 is in the range of 30 ° to 180 ° in the rotation direction 23 of the collector ring 12 (30 ° <θ <180
(See FIG. 3), and the first brush 19 located on the inlet side in the rotation direction 23 is formed of an electrographitic brush and the second brush 19 located on the outlet side. The brush 20 is formed of a metal graphite brush, and the secondary side lead wire 24 of each phase derived from the secondary winding of the winding type three-phase induction motor is the current collector ring 12 of the current collector 14. Connected to the connection terminal 25 corresponding to the brush 1
9 and 20 are connected to the connection terminals 28 and 29 of the brush holder 15 via pick tail wires 26 and 27, and the connection terminal 30 commonly connected to the connection terminals 28 and 29 is connected to the outside via a lead wire 31. It is connected to a resistor (not shown).

As a condition of use, the peripheral speed of the current collector ring 12 is 10 m.
/ Sec, the contact pressure of the brushes 19 and 20 is 200 g / cm
² , the current density is 5 A / cm ² , the angle θ is 90 °, and the experimental results of the present inventor are shown in FIGS. 4 to 7. That is, the surface of the current collector ring 12 is smooth as shown in FIG. 4, which indicates that the oxide film is properly formed on the surface of the current collector ring 12. The temperature rise of the electrographitic first brush 19 is shown by the temperature rise characteristic broken line in FIG.
_As shown in FIG. 19a, the temperature rise of the second metallic graphite brush 20 is shown by the temperature rise characteristic broken line _{20 in} FIG.
As shown in a, both are low. Furthermore,
The wear amount of the electrographitic first brush 19 is shown by the wear amount characteristic broken line ₁₉ b in FIG. 6, and the wear amount of the metal graphite second brush 20 is shown by the wear amount characteristic broken line in FIG.
Is as shown in ₂₀ b, the amount of wear of the second brush 20 of the metal-graphite is also reduced from conventional. And the contact voltage drop is the second by using the two metallic graphite brushes 5, 6.
In the conventional example of FIG. 7, it is high as shown in FIG. 7 (a), and in the first conventional example using two metal graphite brushes 2 and 3, it is low as shown in FIG. 7 (b). However, in the present embodiment using the first brush 19 made of electrographite and the second brush 20 made of metal graphite, the first brush made of metal graphite 2 and 3 is used as shown in FIG. This is equivalent to the conventional example, which shows that the sliding contact resistance is stable in this embodiment.

According to this embodiment as described above, the following operational effects can be obtained. That is, the first brush 19 made of electrographite, which is located on the inlet side in the rotation direction 23 of the current collector ring 12, has a large viscosity coefficient without wear powder adhering to the surface of the current collector ring 12. It has extremely good resistance and has the ability to form an oxide film on the surface of the current collector ring 12 even in a low current density region. On the other hand, the metal graphite second brush 20 located on the outlet side in the direction of rotation 23 of the current collector ring 12 has a function of appropriately polishing the oxide film when it becomes excessive. Can be prevented. Since the metallic graphite second brush 20 has a small specific resistance and a small contact resistance, it has a small contact voltage drop and a low temperature rise, and can be used up to a high current density region. As a result, the problem of the first conventional example that the surface of the collector ring is damaged and the brush is abnormally worn in the low current density region can be eliminated, and in the high current density region, the temperature rises and the spark is generated. The defect of the conventional example can be eliminated, and it can be applied from a low current density region to a high current density region.

FIG. 8, FIG. 9 and FIG. 10 are respectively the second and third aspects of the present invention.
And a fourth embodiment. The difference from the first embodiment is that the first brushes 19 and 1 made of electrographite brushes as two types of brushes for the current collector ring 12 of each phase.
9 and second brushes 20 and 2 composed of metal graphite brushes
It is a point that a total of four 0s are provided. And the eighth
In the second embodiment shown in the figure, the direction of rotation 23 of the collector ring 12
Brushes 19, 20, 19 and 20 are arranged in this order at equal intervals, and in the third embodiment shown in FIG.
2, the brushes 19, 19, 20 and 20 are arranged at equal intervals in the order of rotation 23, and in the embodiment of FIG. 4 shown in FIG. 10, the brushes 19 are arranged along the direction of rotation 23 of the collector ring 12. , 20, 20 and 19 are arranged at equal intervals, and in any case, the angle θ is set within the range of 30 degrees to 180 degrees.

Therefore, the same effects as those of the first embodiment can be obtained by the second to fourth embodiments.

The present invention is not limited to the embodiments described above and shown in the drawings. For example, the present invention can be applied not only to the winding type three-phase induction motor but also to general rotary electric machines requiring a current collecting ring device. Needless to say, the invention can be appropriately modified and implemented without departing from the scope of the invention.

〔The invention's effect〕

As described above, the current collector ring device of the rotating electric machine of the present invention,
Since the electric graphite brush is located on the inlet side in the rotation direction of the current collecting ring and the metal graphite brush is located on the outlet side, the current collecting ring can be adapted to the usage conditions. It has an excellent effect of preventing damage to the surface, generation of sparks and abnormal wear of the brush.

[Brief description of drawings]

1 to 7 show a first embodiment of the present invention.
The figure is a front view, FIG. 2 is a side view showing a partial cross section, FIG. 3 is a brush installation layout diagram, FIG. 4 is a diagram showing damage to the surface of the current collecting ring, and FIG. 5 is a temperature rise characteristic. FIG. 6 and FIG. 6 are wear amount characteristic diagrams, and FIG. 7 (a) to (c) are contact voltage drop characteristic diagrams shown in comparison with the conventional example.
FIG. 11 is a view corresponding to FIG. 3 showing the second, third and fourth embodiments of the present invention, FIGS. 11 to 17 show a conventional example, and FIGS. 11 and 12 are different from each other. An example corresponding to FIG. 3, FIG. 13 (a) and (b), FIG. 14 (a) and (b) and FIG. 15 (a) and (b) are FIG. 4 in the low current density region, Fig. 5 and Fig. 6 equivalent view, 16th
Figures (a) and (b) and Figure 17 are equivalent to Figures 4 and 5 in the high current density region. In the drawings, 12 is a collector ring, 15 is a brush holder, 15a and 15b are holding parts, 19 is a first brush (electrographitic brush), and 20 is a second brush (metallic graphite brush).

Claims (1)

[Claims] 1. A rotary electric machine in which two kinds of brushes are arranged on a current collecting ring of each phase within a range not exceeding an angle of 30 to 180 degrees in a rotation direction thereof, and the brush is positioned on an inlet side in the rotation direction. A current collecting ring device for a rotating electric machine, wherein the brush is an electric graphite brush, and the brush located on the outlet side is a metal graphite brush.