JP5103889B2 - Commutator - Google Patents

Description

  The present invention relates to a commutator structure of a commutator motor, and more particularly to a commutator that suppresses sparks and noise generated between a brush and a commutator.

  In commutator motors that use commutators, sparks between commutator segments (commutator segments) have become significant due to recent miniaturization, higher output, and higher speed, and electrical noise has been generated. Or a reduction in the brush life. In order to suppress the occurrence of sparks between the commutator pieces, it is effective to have a structure in which the commutator pieces are electrically connected by a resistor element, a varistor element, or a capacitor element.

  As a specific example of the commutator having such a structure, for example, there is a commutator structure of a micromotor described in Japanese Utility Model Publication No. 51-44082. In the technique described in the above publication, a ring provided with a resistance film is mounted around a rotating shaft on which a plurality of commutator pieces are arranged. Thereby, each commutator piece will be connected by electrical resistance, and suppression of the spark generation between commutator pieces is achieved.

Further, in Japanese Patent Laid-Open No. 8-237913, each commutator is provided in the groove portion of the anchor portion of the commutator piece due to the problem that the connection between the commutator pieces cannot be secured during high-speed rotation of the rotor. A commutator composed of a material having electric resistance, a material having varistor characteristics, or a material having capacitor characteristics is proposed. Has been.
Japanese Utility Model Publication No. 51-44082 JP-A-2-151243 JP-A-8-237913

  However, in the prior art in which a reinforcing ball is embedded or press-fitted as a method of joining a ceramic having a varistor characteristic and a commutator piece made of a copper alloy, a low contact resistance can be obtained stably during high-speed rotation. I can't. This is because the contact point between the commutator piece and the ceramic having varistor characteristics is small simply by embedding or press-fitting, so in a high voltage, high current motor, the current is concentrated at the contact point between the commutator piece and the varistor surface. Therefore, there is a problem that heat generation due to contact resistance and destruction of the varistor occur. Thus, if the contact resistance between the commutator piece and the ceramic having varistor characteristics is not stable, the absorption characteristics of the rectifier sparks by the varistors vary when the rectifier sparks are generated, which may promote brush wear. In order to improve the contact stability between the commutator piece and the ceramic having varistor characteristics, it is important to obtain contact resistance by increasing the contact area.

  In order to solve the above-described problems, the present invention provides a ring-shaped varistor element embedded in the groove portion of the anchor portion of the commutator pieces arranged circumferentially or at both ends of each commutator piece arranged circumferentially. A commutator formed by embedding a varistor element having a columnar shape or a rod shape (a cross section may be a polygon or the like) in a groove portion provided, and molding the commutator piece and the varistor element integrally with a synthetic resin. In order to stabilize the contact resistance between the piece and the varistor element, the surface of each commutator piece is subjected to soft metal plating.

  The ring-shaped varistor element preferably has a quadrangular cross section or the like so that the contact area with the commutator piece can be increased.

  The commutator of the present invention has a varistor formed in the groove portion of the commutator piece anchor portion or the groove portion provided on both ends of the individual commutator pieces arranged on the circumference by performing soft metal plating on the surface of the commutator piece. When the element is press-fitted, the oxide layer on the plating surface is removed, the fine irregularities on the surface of the commutator element and the varistor element are crushed, and the contact point increases, so that the contact area between the two can be increased. it can. Thereby, the electrical connection between adjacent commutator pieces can be reliably maintained, and the occurrence of sparks between the commutator pieces can be reliably suppressed.

  Further, as a semiconductor element or the like for connecting a commutator piece arranged in a circumferential shape, a ring-shaped or cylindrical shaped body (varistor element) made of ceramic is press-fitted and pressed into a groove portion of the commutator piece, thereby fixing the anchor portion. It is possible to more firmly prevent breakage and displacement due to the centrifugal force applied when the rotor rotates at a higher speed than when only the rotor is supported.

  In the commutator of the present invention, a plurality of commutator pieces whose surfaces are subjected to soft metal plating are arranged on the circumference, and a ring-shaped varistor element is embedded or press-fitted into a groove portion of the commutator piece anchor portion. The commutator is formed by integrally forming the commutator piece and the varistor element, cutting the contact surface with the brush, and removing the plating on the surface.

  Alternatively, a plurality of commutator pieces whose surfaces are subjected to soft metal plating are arranged on the circumference, and cylindrical varistor elements are embedded or press-fitted into grooves provided at both ends of the individual commutator pieces, and a synthetic resin The commutator is formed by integrally forming the commutator piece and the varistor element, cutting the contact surface with the brush, and removing the plating on the surface.

  As the plating material on the surface of the commutator piece, a soft metal material such as tin plating or solder plating (SnPb-based, SnAg-based, SnAgCu-based, SnCu-based), gold plating, silver plating, or a precious metal plating that is difficult to oxidize is used. good. By using these, the contact area with the varistor made of ceramic can be obtained, and the contact resistance can be further reduced.

  Furthermore, the thickness of the plating is preferably 3 μm or more and 7 μm or less where the contact resistance is stabilized, and 10 μm or less is desirable in consideration of manufacturing variations. When the thickness of the plating is 3 μm or less, the contact resistance becomes high and a sufficient effect cannot be obtained. In addition, since it is a soft metal, the holding strength of the commutator piece decreases at 10 μm or more due to the difference in hardness from the surrounding metal, and the step between adjacent commutator pieces increases during high-speed rotation. Causes wear.

  Hereinafter, a commutator according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show the configuration of a mold commutator according to an embodiment of the present invention. FIG. 1 is a cross-sectional view of the mold commutator cut at right angles to the rotation axis. FIG. It is sectional drawing cut | disconnected in parallel.

  FIG. 1 is a cross-sectional view of the commutator of the present invention cut at a right angle to the rotation axis. A groove portion 6 is formed at both ends of each commutator piece 1 made of a copper alloy, and a ceramic columnar varistor 4 is embedded in the groove portion 6.

  Moreover, FIG. 2 represents the axial cross section of the commutator of 1st invention of this application.

  The surface of the commutator piece 1 is subjected to tin plating 2 having a thickness of 5 μm, and a cylindrical varistor element 4 is press-fitted into the groove portions 6 provided at both ends of each commutator piece. After press-fitting, molding is performed with phenol resin 5 containing glass fiber. The boss 5 is used for fixing to the motor shaft. Next, a portion where adjacent commutator pieces are in contact with each other is cut, and slits at appropriate intervals are provided between the commutators. Then, the outer periphery of the commutator which is a contact surface with the brush was cut and polished to remove the plating layer, thereby obtaining a mold commutator with a built-in varistor.

  FIG. 3 shows an axial section of the commutator according to the second aspect of the present invention.

  The surface of the commutator piece 1 made of a copper alloy is subjected to tin plating with a thickness of 5 μm, and the commutator piece 1 is arranged circumferentially. Thereafter, ring-shaped varistor elements 9 having varistor characteristics are press-fitted into the grooves 8 of the anchor legs 3 of the plurality of commutator pieces arranged circumferentially. After press-fitting, molding is performed with phenol resin containing glass fiber. Next, a portion where adjacent commutator pieces are in contact with each other is cut, and slits at appropriate intervals are provided between the commutators. Then, the outer periphery of the commutator which is a contact surface with the brush was cut and polished to remove the plating layer, thereby obtaining a mold commutator with a built-in varistor.

  Next, optimization of the plating thickness was studied.

  The surface of the commutator piece 1 made of a copper alloy was subjected to tin plating with a thickness of 1 to 10 μm. Grooves 6 are formed at both ends of the legs 3 of the commutator pieces 1 arranged in a circle and adjacent individual commutator pieces, and a cylindrical varistor element 4 is press-fitted into the grooves 6. After press-fitting, molding is performed with phenol resin containing glass fiber. Next, a portion where adjacent commutator pieces are in contact with each other is cut, and slits 10 with appropriate intervals are provided between the commutators. Thereafter, the outer periphery of the commutator was cut and polished to remove the plating layer, thereby obtaining a mold commutator.

  FIG. 4 is a graph showing the results of measuring the relationship between the plating thickness applied to the commutator piece 1 and the resistance between the pieces. As is apparent from this graph, the contact resistance is stable when the plating thickness applied to the commutator piece is 3 μm to 10 μm.

  Further, in a high-speed spin test at 6000 rpm rotation at 220 ° C., if the plating thickness is 10 μm or more, the step between adjacent commutator pieces becomes large, and the rectification noise and wear of the brush are promoted. Therefore, it can be said that the optimum thickness of the plating is 3 μm to 10 μm.

  Since the commutator of the present invention can suppress the generation of commutation sparks and can suppress the step between adjacent commutator pieces, commutation noise and wear of the brush are reduced. Therefore, it is useful for an electric motor that performs high input and high speed rotation.

Axial direction vertical sectional view of a mold commutator in Example 1 of the present invention Axial parallel sectional view of mold commutator in Example 1 of the present invention Axial parallel sectional view of mold commutator in Example 2 of the present invention Graph showing the relationship between plating thickness and resistance between commutator pieces

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commutator piece 2 Commutator piece plating part 3 Commutator anchor leg part 4 Cylindrical varistor element 5 Phenolic resin containing glass fiber 6 Groove part provided at both ends of commutator piece 7 Boss 8 Commutator anchor groove part 9 Ring-shaped varistor element 10 Slit 11 Cutting surface

Claims (3)

A commutator formed by embedding a ring-shaped varistor element in a groove portion of an anchor part between circumferentially arranged commutator pieces, and molding the commutator piece and the varistor element integrally with a synthetic resin. a commutator having been subjected to soft metal plating on the surface of the pieces, the commutator segment surface of the plating thickness of the soft metal plating 3μ or more, 10 [mu] or less and the commutator. In a commutator formed by embedding cylindrical or bar-shaped varistor elements in grooves provided at both ends of individual commutator pieces arranged in a circle, and molding the commutator pieces and the varistor elements integrally with a synthetic resin. , the rectifier on the surface of the child piece a commutator which has been subjected to soft metal plating, the commutator segment surface of the plating thickness of the soft metal plating 3μ above, commutator having a 10μ or less. Motor with commutator according to claim 1 or claim 2.