JP4588392B2 - Carbon brush for electric machine - Google Patents

Description

  The present invention relates to a carbon brush for an electric machine, and more particularly, to a carbon brush for an electric machine used for a small motor.

  Electric motors are becoming smaller, larger capacity, and higher output. For example, a motor used in a vacuum cleaner is required to be smaller and have a strong suction force. For this reason, the outer diameter of the fan of the motor is reduced, and the motor is rotated at an ultra high speed (30,000 rpm or more). In such an ultra-high-speed rotation motor, normal electrical operation is achieved by maintaining a good sliding state between a carbon brush for an electric machine (hereinafter referred to as a carbon brush) and a commutator that is a conductive rotating body. Maintaining contact has been an important issue.

  Conventionally, in view of such a problem, a so-called resin bond type carbon brush in which graphite powder is bonded with a synthetic resin has been widely used. This resin-bonded carbon brush is made slippery with graphite powder and has good seating properties with the resin, thereby ensuring normal electrical contact.

  Moreover, in a vacuum cleaner or the like, the current density of the carbon brush can be increased by increasing the input of the motor in order to increase the suction force (suction power). However, in the case of such a method, in particular, a resin-bonded carbon brush may cause a rectification failure due to an increase in temperature of the carbon brush due to long-time use or an increase in wear of the carbon brush.

Furthermore, the background of input restriction has to be taken into consideration, and there has been a further demand for a motor that can obtain a higher output for a given input.
Under such circumstances, there has been a strong demand for a carbon brush capable of ensuring stable commutation and providing high efficiency (output with respect to input) to the motor.

As a countermeasure for such a problem, graphite powder, 0.5 to 5% by weight of granular aluminum powder of approximately 200 mesh or less and a binder are mixed, and after this is pressure-molded, 350 A carbon brush obtained by heat treatment at a temperature of ℃ or less is disclosed (for example, see Patent Document 1). Also, after graphite powder, 0.2 to 3.0% by weight of aluminum powder and 2 to 10% by weight of copper powder and thermosetting resin are mixed with the graphite powder, and then molded. A carbon brush obtained by firing is disclosed (for example, see Patent Document 2).
Japanese Patent Publication No. 58-58787 JP-A 64-88844

By the way, in the carbon brush containing the metal powder described above, the techniques disclosed in Patent Documents 1 and 2 have the following problems (1) to (4).
(1) Since the metal powder grinds the commutator, the amount of wear of the commutator increases.
(2) When the adhesion between the carbon substrate and the metal powder is poor, the metal powder may be detached.
(3) Since metal powder is used, the metal powder tends to be unevenly distributed in the material of the carbon brush.
(4) If the metal powder is contained in a large amount, the elastic coefficient of the carbon brush becomes high, and the brush seating property deteriorates, for example, the brush easily jumps during rotation. Will shorten the service life.

  The present invention was devised in view of such circumstances, ensuring more stable commutation, high efficiency for motors, long life, temperature reduction, sliding noise suppression, commutator wear reduction. An object of the present invention is to provide a carbon brush for an electric machine from which can be obtained.

In order to solve the above problems, an electric machine carbon brush according to the present invention is an electric machine carbon brush pressed against a conductive rotating body, and includes an aggregate containing at least one carbon and a binder. By immersing the brush base material in an impregnating solution in which the material is a brush base material and the metal compound Cu (edta) is dissolved in water, the metal compound Cu is in the pores of the brush base material with respect to the brush base material. And uniformly impregnated at a ratio of 0.16 to 0.96% by weight .

  The brush base material composed of the aggregate and the binder has void portions called “pores”. Here, impregnation means that a metal compound is present in the material in the pores. .

  The size and volume of the existing pores vary depending on the type of brush, manufacturing method, manufacturing conditions, and the like. The pores exist in the entire brush, and there are open pores connected from the brush surface to the inside and closed pores isolated in the brush. Hereinafter, the term “pores” simply means open pores.

  Since the metal compound is in a state of being dissolved in an aqueous solution or an organic solvent, the metal compound can be uniformly impregnated into the pores of the brush while maintaining the molecular level. By uniformly impregnating the metal pores in the brush pores, the metal compound acts uniformly on the entire sliding surface with the rotating body for a long time, and the mechanical resistance on the sliding surface is reduced. Thus, it is considered that by achieving good slidability, motor efficiency can be improved, long life, temperature can be reduced, sliding noise can be suppressed, and commutator wear can be reduced.

In the above configuration, the metal compound may be a metal complex compound or a chelate compound. Furthermore, the ligand of the metal compound is preferably any one of an amine compound, a ketone compound, and an oxime compound.

  Further, in the carbon brush for electric machine of the present invention, an electrically conductive metal film is formed on at least a part of the surface of the carbon brush excluding the surface in contact with the conductive rotating body of the carbon brush for electric machine. Can be used.

  Thus, the efficiency with respect to a motor can further be improved by using the brush in which the metal membrane | film | coat is formed.

  According to the present invention, the above configuration improves the efficiency of the motor, reduces the amount of wear of the brush, and extends the life of the brush. In addition, when the temperature is high, other components associated with the motor are likely to deteriorate. However, in the present invention, the temperature of the brush is lowered, so that such a problem is solved. Further, it is beneficial in that the sliding noise is reduced and commutator wear is reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a motor using a brush according to an embodiment of the present invention.

  The brush 1 is in contact with the rotating body 2 that is a commutator of the motor and the lower surface 1a of the brush 1 and slides at that portion. The brush 1 is held in a state of being surrounded by a brush holder 4.

  The brush 1 has a base material made of an aggregate containing carbon as at least one component and a binder. This substrate has pores as described above, and in the present embodiment, the pores of the brush substrate are impregnated with a metal compound.

  The pores of the brush 1 may be, for example, a brush base material having a small pore radius with an average pore radius determined by a mercury intrusion method of 1 μm or less.

  As a base material of the brush 1, a carbon graphite brush called CG (Carbon Graphite) system, an electric graphite brush called EG (Electric Graphite) system, and a resin bond system that is a synthetic resin whose binder is not carbonized A metal brush using metal powder such as a brush, copper powder, iron powder, silver powder or the like as part of the aggregate can be used, and a resin bond brush is particularly preferable.

  The manufacturing method of this resin bond type brush base material is demonstrated below.

  First, these aggregates and a binder are knead | mixed by making 10-40 weight part of binder into an approximate compounding ratio with respect to 100 weight part of aggregate.

  As this aggregate, artificial graphite, natural graphite, expanded graphite and the like can be used. Of these, artificial graphite in which the crystallinity of graphite is not so developed, or a configuration in which natural graphite and artificial graphite are blended is preferable.

  On the other hand, a synthetic resin is used as the binder, and either a thermosetting synthetic resin or a thermoplastic synthetic resin may be used, or a mixture thereof may be used. Particularly suitable synthetic resins include epoxy resins, phenol resins, polyester resins, vinyl ester resins, furan resins, polyamide resins, and polyimide resins.

  When kneading, an appropriate amount of an organic solvent such as alcohols or acetone may be added as necessary. Moreover, you may add an additive, for example, a solid lubricant, and a film | membrane regulator, to some aggregates as needed. For example, a solid lubricant such as molybdenum disulfide or tungsten disulfide, or a film modifier such as alumina, silica, or silicon carbide may be added.

  Next, the kneaded mass is pulverized to prepare a powder for molding. Thereafter, the powder is formed into a brush base material shape. And it heat-processes under the temperature (generally 100-300 degreeC) which resin hardens | cures to a molded object, and resin is hardened.

  Moreover, the brush 1 may form an electrically conductive metal film on the entire surface or a part of the side surface 1b and the upper surface 1a excluding the lower surface 1a of the brush 1 at the stage of the brush substrate. Examples of the material of the coating include nickel, copper, and silver. Moreover, although the thickness of this film | membrane is about 3-100 micrometers in general, it is not limited to this.

  The metal film can be formed by a known method such as electrolytic plating or electroless plating.

  As a method of incorporating the metal compound into the brush, a method of mixing these together with an aggregate or a binder in the course of manufacturing the brush, or a method of impregnating them into a previously manufactured brush base material can be employed. .

  Next, the structure which impregnates a brush base material with a metal compound is demonstrated.

  The metal compound is a metal compound that is soluble in water or an organic solvent. The metal compound is preferably a metal complex compound, and the metal complex compound is preferably a chelate compound.

  In addition, the metal species contained in this metal compound may be any metal of 3 to 14 groups and 3 to 5 periods in the long-period element periodic table. In this case, Al, Ti, Fe, Ni, Cu, Zn, Ag , Sn is preferable. Among these metals, Fe, Cu, Zn, and Ag are particularly preferable.

Such metal compounds may be ion-bonding or covalent-bonding, inorganic salts such as sulfates, nitrates and hydrochlorides of the above metals, acetates, oxalates and benzoates of the above metals , Organic acid salts such as benzene sulfonate, metal complex compounds and chelate compounds in which the above metal is the central atom, but are not particularly limited, and commercially available products can be used.
The metal complex compound or chelate compound in which the metal is a central atom is not particularly limited, and commercially available products can be used.

  The ligand of the metal complex compound or chelate compound in which the metal is the central atom is ethylenediamine (en), diethylenetriamine (dien), triethylenetetramine (trien), ethylenediaminetetraacetic acid (edta), pyridine (bpy), terpyridine ( and an amine compound such as terpy), a ketone compound such as acetylacetone (acac), and an oxime compound such as dimethylglyoxime (dmg).

  For impregnation of the brush base material with the metal compound, first, the metal compound and water or an organic solvent are mixed to prepare the impregnation liquid. Since the metal compound and water or the organic solvent are easily mixed, the impregnating liquid can be prepared by a simple operation such as stirring manually with a stirring rod. The amount of the metal compound in the impregnation liquid is appropriately determined according to the target impregnation rate, impregnation conditions, the type of the selected substrate, and the like.

  The adjusted impregnating liquid penetrates into the fine pores to the inside by capillary action and is uniformly impregnated into the pores of the brush base material. Therefore, the impregnation can be performed by simply immersing the brush substrate in the impregnating liquid. However, vacuum degassing and pressurizing operations known as general impregnation methods may be used in combination.

  The temperature of the impregnating liquid can be appropriately selected according to the boiling point of water or the organic solvent, and can be performed in a temperature range from about 20 to 30 ° C. to 40 to 60 ° C. In addition, the immersion time is appropriately determined depending on conditions such as the viscosity of the impregnating solution, temperature, and brush base material, and is, for example, about 10 to 60 minutes.

  After the brush is immersed for a certain time, the brush is taken out and dried at a temperature of 100 ° C. or higher to remove water or an organic solvent impregnated in the brush. When the weight of the brush by drying reaches a constant weight, it is considered that the removal has reached the end point, and the drying is finished. The weight of the metal compound left on the brush substrate is the weight impregnated.

  Thus, the lead wire 3 etc. are suitably attached to the brush impregnated with the metal compound.

In the present embodiment, a mixture of a metal compound having a kinematic viscosity of 10 to 20000 mm ² / s (20 ° C.) and water or an organic solvent is preferable. Furthermore, it is more preferable to have a kinematic viscosity of 10 to 1000 mm ² / s.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Example]
First, a resin-bonded brush base material used in this example was produced as follows.

  30 parts by weight of epoxy resin is blended with 100 parts by weight of artificial graphite powder (average particle size 100 μm, ash content 5% by weight or less), and at a normal temperature, the artificial graphite powder and the resin are uniformly mixed. Kneading was carried out for a time (30 to 120 minutes).

  This kneaded product was pulverized to 40 mesh or less to obtain a molding powder for molding into a brush. The molding powder was molded into a brush shape with a mold (size: 5.5 × 6 × 25 mm), and then heat-treated at 150 ° C. using a commercially available dryer to cure the resin.

This brush base material had a bulk density of 1.45 g / cm ³ and a resistivity of 700 μΩ · m. The brush substrate had a cumulative pore volume of 212 mm ³ / g and an average pore radius of 0.76 μm. In addition, the porosity was calculated | required by the mercury intrusion method (The mercury porosimeter FISONS Instrument company make, model MAPO120 and PO2000 was used).

  In this example, first, the brush base material thus prepared is used as an impregnation liquid in which the metal compound Cu (edta) is dissolved in water, and the time during which the brush base material is immersed in the impregnation liquid is changed. As a result, metal compound-impregnated brushes (4 types) having impregnation rates of 0.16 wt%, 0.32 wt%, 0.48 wt%, and 0.96 wt% were obtained. The impregnation rate (% by weight) is expressed as a percentage by multiplying the value obtained by dividing the weight of the increase due to impregnation by the weight of the brush before impregnation by 100.

  To measure the motor efficiency, first, lead wires were attached to these brushes, and then set to a test motor with a spring pressure of 41 kPa. Suction power P (W) was measured for each brush under certain conditions. In addition, about 1550W of electric power was input into the motor under the voltage 230V and 60Hz. At this time, the rotation speed of the motor was about 34000 rpm.

  The efficiency of the motor was calculated by equation (1).

η = (P / I) x 100 (1)
Here, η is the motor efficiency (%), P is the suction power (W), and I is the input (W).

  Table 1 shows the motor efficiency test results obtained when the brushes not impregnated with the metal compound were used, and the motor efficiency tests obtained when the four types of metal compound impregnated brushes were used. Shown in The impregnation rate of 0% by weight is not included in this example, and is described as Comparative Example (1).

  Also, the amount of wear of the brush per 100 hours (mm / 100h), the temperature of the outer periphery of the brush holder (° C), the sliding sound of the brush (dB), the amount of wear of the commutator per 100 hours (mm / 100h) Table 1 shows the results obtained by measuring the values.

  In addition, the temperature measured the front-end | tip part temperature by the side of the rotary body of the outer periphery of the brush holder 4 using the thermocouple.

  The sliding sound was measured at a position 10 cm (distance) away from the brush holder 4 with a sound level meter (LA-210 manufactured by ONOSOKKI).

  Further, brushes containing 0.5% by weight of metal powder Al and 0.5% by weight of metal powder Cu were referred to as Comparative Example (2) and Comparative Example (3), respectively. The efficiency was calculated and each measurement was performed.

  The test results are shown in Table 2.

表１に示すように、試料番号(2) 〜(5) では、モータの効率がそれぞれ４１．２％、４１．１％、４１．１％、４１．１％であり、金属化合物Ｃｕ（ｅｄｔａ）を含浸していないブラシ（無含浸ブラシ）のモータの効率４１．０％に対して０．１〜０．２％高い値を示した。

As shown in Table 1, in the sample numbers (2) to (5), the motor efficiency is 41.2%, 41.1%, 41.1%, 41.1%, respectively, and the metal compound Cu (edta ) Was 0.1 to 0.2% higher than the efficiency of the motor of 41.0%.

  An improvement in the motor efficiency of 0.1 to 0.2% is considered to be a significant effect in the field of small motors used in vacuum cleaners and the like. Therefore, the improvement in the efficiency of such a motor is evaluated as having great significance and high utility value. In particular, in a situation where the input is restricted by the motor standard, etc., considering that the output cannot be increased by increasing the input, a brush with higher motor efficiency is thus obtained. It is essential to be required.

  Also, the brush wear amount per 100 hours is 7-9 (mm / 100h) for sample numbers (2) to (5), which is dramatic compared to 10 (mm / 100h) for the non-impregnated brush. Reduced to Moreover, about temperature, it was restrained to 93 degrees C or less. Further, the sliding noise was lower in the sample numbers (2) to (4) than the 110 dB of the non-impregnated brush. The amount of commutator wear per 100 hours is 0.04 to 0.05 (mm / 100h) for sample numbers (2) to (5), and 0.12 (mm / 100h) for the non-impregnated brush. Compared with, it was drastically reduced.

  In Comparative Examples (2) and (3) of sample numbers (6) and (7) containing metal powder, the efficiency of the motor showed a high value of 41.2% when Al powder was contained. However, when Cu powder was included, the efficiency of the motor was as low as 40.7%. However, no effect as in the above example was observed for the amount of brush wear per 100 hours, temperature, and sliding noise. Further, as is clear from the results of this comparative example (3) (sample number (7)), the brush containing Cu powder impregnates the metal compound Cu (edta) of this example, although the efficiency of the motor decreases. It was proved that the effect of the brush was remarkable as described above.

  Further, a copper film having a thickness of 10 μm was formed by electroless plating of copper on the entire surface of the surrounding surface except for the portion of the brush base material produced in this example that was in contact with the rotating portion of the brush.

  The same metal compound was impregnated into the brush base material on which this copper film was formed by the method described above (this example). As a result, the impregnation rate of the metal compound with respect to the brush base material on which the copper film was formed was about 20% lower than that of the brush without the copper film. However, in the case of a brush base material on which a copper film was formed, the impregnation rate equivalent to that for a brush without a copper film could be obtained by a method of increasing the immersion time or changing the immersion temperature. .

  Such a brush contributes to the above effect in that the effect of the electrically conductive metal film on the brush surface, that is, the temperature rise of the brush can be suppressed and stable rectification can be maintained over a long period of time.

  An electric machine equipped with a motor such as a vacuum cleaner is required to have high motor efficiency especially when there is an input restriction due to the motor standard or the like. The present invention is applicable to such a motor. Furthermore, the life of the brush is long, the sliding noise can be reduced, it is economically beneficial, and it can contribute to the miniaturization of the motor.

  FIG. 1 is a perspective view showing a schematic configuration of a motor using a brush according to an embodiment of the present invention.

Explanation of symbols

1 Brush 2 Rotating body 3 Lead wire 4 Brush holder

Claims (5)

A carbon brush for an electric machine pressed against a conductive rotating body,
A material composed of aggregate and binder containing carbon as at least one component is a brush base material,
By immersing the brush base material in an impregnating solution in which the metal compound Cu (edta) is dissolved in water, the metal compound Cu is 0.16 to 0.00 in the pores of the brush base material with respect to the brush base material. A carbon brush for an electric machine, which is uniformly impregnated at a ratio of 96% by weight. The carbon brush for an electric machine according to claim 1,
The carbon brush for an electric machine , wherein the ligand of the metal compound is any one of an amine compound, a ketone compound, and an oxime compound . The carbon brush for an electric machine according to claim 1 or 2,
The carbon brush for an electric machine , wherein the brush base material is any one of a carbon graphite brush, an electrographite brush, and a resin bond brush. A carbon brush for an electric machine according to any one of claims 1 to 3,
A carbon for electric machines, characterized in that an electrically conductive metal film is formed on at least a part of the surface of the carbon brush excluding the surface of the carbon brush for electric machines that contacts the conductive rotating body. brush. A method for producing a carbon brush for an electric machine according to any one of claims 1 to 4,
A material composed of aggregate and binder containing carbon as at least one component is a brush base material,
By immersing the brush base material in an impregnating solution in which the metal compound Cu (edta) is dissolved in water, the metal compound Cu is introduced into the pores of the brush base material in an amount of 0.16 to 0.00 with respect to the brush base material. A method for producing a carbon brush for an electric machine, characterized by uniformly impregnating at a ratio of 96% by weight.

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