JP4802558B2 - Laminated resin brush - Google Patents

Description

  The present invention relates to an electric motor with a brush used for, for example, an electric blower, and more particularly to a laminated resin brush for a rotating electrical machine used for those electric motors.

  In recent years, motors with brushes have been further reduced in size and weight by increasing the speed, efficiency, and voltage of products such as electric blowers that are used. By the way, this type of electric motor has a poor rectification performance when a low resistance brush is used, and conversely, when a high resistance brush is used, the rectification performance is improved. There are challenges.

  In particular, brushes used in high-voltage motors tend to generate sparks (contact sparks) due to their high current density, which increases brush wear and noise, shortening the product life (durability). is the current situation.

  Therefore, in order to reduce the coefficient of friction, which is an important factor for noise reduction characteristics, and the low resistivity, which is an important element for output characteristics, in the production of metallic graphite brushes, a specific amount of natural graphite powder and electrolytic copper There has been proposed a metal graphite brush formed by mixing powder, molybdenum disulfide as an additive, novolac-type phenol resin, furfural resin, and the like at a specific ratio (see Patent Document 1).

  However, with the increase in speed and efficiency, there is a limit to improving the performance of the brush material in order to solve these problems, so the brush structure is devised. As one of them, the problem is solved with a laminated brush from the form of a single brush (see Patent Document 2).

  In this type of laminated brush, a low-resistance brush material and a high-resistance brush material are laminated into two or three parts to improve motor output and brush durability.

FIG. 4 is a schematic diagram in which the laminated brush of Patent Document 2 is used. When the brush 11 composed of the high resistance layer 12 and the low resistance layer 13 slides on the commutator 15 piece in the direction 17, a short-circuit current 16 flows through the brush. In particular, when the low resistance layer 13 exists between the commutators, since the brush resistance is low, sparks are generated, causing problems in wear and durability of the brush.
Japanese Patent Application Laid-Open No. 07-213022 Japanese Patent Publication No. 06-007505

  As described above, even in the conventional laminated brush, when the motor is operated for a long time, the commutator surface is blackened, and the spark cannot be sufficiently suppressed as time passes, resulting in brush wear. Impacts durability.

  That is, as shown in FIG. 4, the laminated brush has a total thickness of 5 mm and each layer has a four-phase structure with a thickness A of 1.25 mm, and the width B between the commutator pieces provided in the electric motor in which the laminated brush is used. When A is 0.55 mm, A> B is satisfied, a short-circuit current flows through the inside of the brush, and a spark phenomenon occurs between the laminated brush and the commutator piece.

  The present invention is a laminated resin brush intended to solve the above problems by optimizing the brush material and the structure of the brush.

  The laminated resin brush of the present invention comprises a laminate of a high resistance layer mainly composed of an epoxy resin and a laminate of a low resistance layer mainly composed of a carbon nanotube and an epoxy resin alternately laminated in at least four layers. As a result, the life of the laminated resin brush can be improved, and the wear of the commutator of the motor can be reduced.

  Further, the laminated resin brush of the present invention is a laminated resin in which a laminate of a high resistance layer mainly composed of an epoxy resin and a laminate of a low resistance layer mainly composed of a carbon nanotube are alternately laminated in at least four layers. The thickness (A) of each layer of the laminated resin brush is A <B in relation to the width (B) between commutator pieces provided in the electric motor in which the laminated resin brush is used. Thus, the spark phenomenon between the laminated resin brush and the commutator piece can be reduced.

  The laminated resin brush of the present invention reduces the spark phenomenon by laminating a large number of high resistance layers and low resistance layers alternately and shielding the current caused by the counter electromotive force generated between the commutators. Can improve brush life and commutator wear without reducing efficiency.

  The laminated resin brush of the present invention comprises a laminate of a high resistance layer mainly composed of an epoxy resin and a laminate of a low resistance layer mainly composed of a carbon nanotube and an epoxy resin alternately laminated in at least four layers. It is the laminated resin brush characterized by having performed. With this configuration, it is possible to improve the life of the laminated resin brush and further reduce the wear of the commutator of the motor.

  And a laminated resin brush in which a laminate of a high resistance layer mainly composed of epoxy resin and a laminate of a low resistance layer mainly composed of carbon nanotubes are alternately laminated in at least four layers, The relationship between the thickness (A) of each layer of the brush and the width (B) between the commutator pieces provided in the electric motor in which the laminated resin brush is used is A <B. The spark phenomenon between the commutator pieces can be reduced.

  Further, the low resistance layer and the high resistance layer contain molybdenum disulfide as a solid lubricant, so that the sliding characteristics at high temperature are improved and the brush life is effective.

  Examples of the present invention will be described below.

Example 1
5% by weight of carbon nanotubes having an average diameter of 500 nm, 35% of graphite, and 60% by weight of epoxy resin were kneaded, dried and pulverized to obtain a resin mixed powder having an average particle diameter of 150 μm. The resin-mixed graphite powder was weighed to 3% by weight of molybdenum disulfide, and was secondarily mixed with a mixer for 1 hour to obtain a low resistance portion mixed powder.

  The low resistance part mixed powder was filled in a predetermined mold, molded (heat compression molding) at a pressure of 180 ° C. and 100 MPa, and molded to a thickness of 0.4 mm. Further, a thermosetting adhesive (epoxy resin 100%) is applied to the surface of each molded body, an adhesive layer is formed to have a thickness of 0.1 mm, and the low resistance portions are alternately laminated with the adhesive layer and cured at 230 ° C. It was. This adhesive layer served as a high resistance layer. Then, after installing the pigtail wire at a predetermined position, the outer shape was machined so that a laminated resin brush having 20 layers had dimensions of 32 mm × 10 mm × thickness 5 mm (the same applies to the following examples and comparative examples) Got a brush of dimensions).

(Example 2)
20% by weight of artificial graphite having an average particle size of 100 μm and 80% by weight of epoxy resin were kneaded, dried and pulverized to obtain a resin mixed graphite powder having an average particle size of 150 μm. 3% by weight of molybdenum disulfide having an average particle diameter of 5 μm was added to the resin-mixed graphite powder, and these were secondarily mixed with a mixer for 1 hour to obtain a high resistance portion mixed powder.

  40% by weight of carbon nanotubes having an average diameter of 500 nm and 60% by weight of an epoxy resin were kneaded, dried and pulverized to obtain a resin mixed powder having an average particle diameter of 150 μm. Resin mixed graphite powder and molybdenum disulfide having an average particle diameter of 5 μm were weighed to 3% by weight, and these were secondarily mixed with a mixer for 1 hour to obtain a low resistance portion mixed powder.

  Next, in accordance with the desired shape of the brush, the powder molding die is filled with the high resistance part mixed powder and the low resistance part mixed powder obtained above separately at predetermined positions, and a pigtail line is further provided at the predetermined position. After installation, it was molded (cold compression molding) at room temperature and a pressure of 150 MPa, and then fired at 230 ° C. Each forming layer had a thickness of 0.4 mm. Next, the outer shape was machined so that the laminated resin brush having 12 layers had dimensions of 32 mm × 10 mm × thickness 5 mm.

(Example 3)
20% by weight of artificial graphite having an average particle size of 100 μm and 80% by weight of epoxy resin were kneaded, dried and pulverized to obtain a resin mixed graphite powder having an average particle size of 150 μm. Resin mixed graphite powder and molybdenum disulfide having an average particle diameter of 5 μm were weighed to 3% by weight, and these were secondarily mixed with a mixer for 1 hour to obtain a high resistance portion mixed powder.

  40% by weight of carbon nanotubes having an average diameter of 500 nm and 60% by weight of an epoxy resin were kneaded, dried and pulverized to obtain a resin mixed powder having an average particle diameter of 150 μm. Resin mixed graphite powder and molybdenum disulfide having an average particle diameter of 5 μm were weighed to 3% by weight, and these were secondarily mixed with a mixer for 1 hour to obtain a low resistance portion mixed powder.

  Next, in accordance with the desired shape of the brush, the powder molding die is filled with the high resistance part mixed powder and the low resistance part mixed powder obtained above separately at predetermined positions, and a pigtail line is further provided at the predetermined position. After installation, it was molded (heat compression molding) at 180 ° C. and a pressure of 100 MPa, and fired at 230 ° C. in a reducing atmosphere. Next, the outer shape was machined so that the laminated resin brush having 12 layers had dimensions of 32 mm × 10 mm × thickness 5 mm.

  In Examples 1 to 3, a laminated resin brush 1 composed of a high resistance layer 2, a low resistance layer 3, and a pigtail wire 4 as shown in FIG. FIG. 2 is a schematic view in which the laminated brush of the present invention is used. When the brush 1 comprised of the high resistance layer 2 and the low resistance layer 3 slides on the commutator 5 piece in the direction 7, the short circuit current 6 flows though passing through the brush and being weak.

  Normally, cold compression molding is performed as in Example 2. However, the orientation of the carbon nanotubes is adjusted by molding the laminated resin brush by the heating and pressing method as in Example 1 or 3. There is an effect, and the efficiency can be improved without impairing the rectification performance.

(Comparative Example 1)
As shown in FIG. 3, 84% by weight of artificial graphite having an average particle size of 100 μm and 16% by weight of epoxy resin were kneaded, dried and pulverized to obtain a resin mixed graphite powder having an average particle size of 150 μm. Next, in accordance with the shape of the desired brush, the powder mixture is filled with the mixed powder obtained above at a predetermined position, and the pigtail wire 4 is installed at a predetermined position. Molded and fired at 230 ° C. in a reducing atmosphere. Next, the outer shape was machined so that the brush had a size of 32 mm × 10 mm × thickness 5 mm, and a single layer brush 20 was obtained.

  Next, using a laminated resin brush obtained in Examples 1 to 3 and a single layer brush obtained in Comparative Example 1, an actual machine durability test (brush life, output deterioration rate, commutator wear) of a blower motor for a vacuum cleaner was performed. went. The results are shown in Table 1. Each evaluation is as follows.

  Further, in the actual machine durability test of the vacuum cleaner motor, a blower motor of 100 V and 1300 W was continuously operated, the brush life was calculated from the difference in dimensions after the test with respect to the dimensions before the test, and the efficiency was compared with the initial efficiency. The commutator wear is a value obtained from the wear difference before and after the life test.

  As shown in Table 1, when the comparative example and Example 3 were compared in the test results, the life increased by 11% at 536 hours against 482 hours, and the efficiency increased by 1.8% at 50.1% against 48.3%. % Increase and wear decreased slightly by 90 μm against 190 μm, and performance improved in all evaluation items of life, output efficiency, and commutator wear.

  Similarly, in Example 1 and Example 2, the laminated resin brush has a longer brush life and higher output efficiency than the single-layer brush of the comparative example, and less wear on the commutator.

  In Examples 1 to 3, carbon nanotubes are included in the low resistance layer in order to ensure slidability. With respect to the fiber diameter of these carbon tubes, it is preferable to use an average diameter of 0.1 μm or less in terms of improving efficiency and improving mechanical strength.

  Furthermore, as shown in FIG. 2, the thickness A (0.4 mm) of each layer of the laminated resin brush is such that the width B (0.55 mm) between the commutator pieces provided in the electric motor in which the laminated resin brush is used. In the relationship, by setting A <B, the short-circuit current can be suppressed, so that the spark phenomenon between the laminated resin brush and the commutator piece of the motor can be reduced.

  In addition to molybdenum disulfide, tungsten disulfide or the like may be used as the solid lubricant in order to improve sliding characteristics at high temperatures.

  Furthermore, the resin as the binder may be an epoxy resin or a phenol resin.

  Furthermore, as shown in FIG. 2, the direction of attachment of the pigtail line 4 can improve the rectification performance if it is attached perpendicularly from the rectification entry surface direction 7. This is necessary for equal current to flow between each layer.

  The laminated resin brush of the present invention is excellent in wear resistance, can improve the life of the brush as well as the life of the motor commutator, and can be used in a wide range of brushed motors such as electric blowers and automobile motors. Available.

The perspective view of the laminated resin brush in one Example of this invention Schematic diagram of the laminated resin brush and commutator piece width Perspective view of a single-layer brush as a comparative example used in an actual machine durability test of the same laminated resin brush Schematic diagram of conventional laminated brush and commutator piece width

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminated resin brush 2 High resistance part 3 Low resistance part 4 Pigtail wire 5 Commutator piece 6 Short circuit current 7 Commutator rotation direction A Width of each brush layer B Width between commutator pieces

Claims (4)

A laminated resin brush obtained by alternately laminating at least four layers of a high resistance layer mainly composed of an epoxy resin and a low resistance layer made of an epoxy resin containing at least carbon nanotubes, followed by heat compression molding , the laminated resin brush thickness of each layer (a) is, in relation to the laminated resin brush commutator pieces of the provided electric motors used width (B), characterized in that the a <B Multilayer resin brush. The laminated resin brush according to claim 1, wherein the high resistance layer is an epoxy resin containing graphite. The laminated resin brush according to claim 1 or 2, wherein the low-resistance layer is an epoxy resin containing 40% by weight of carbon nanotubes having an average diameter of 500 nm. The low-resistance layer and any one laminated resin brush according to claim 1 to 3 in which the high resistance layer is characterized that you containing molybdenum disulfide.

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