JP2011142703A - Commutator motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a commutator motor where a brush is excellent in good electrical conductivity and durability and high efficiency and long operating life are achieved. <P>SOLUTION: In the commutator motor with a structure where the brush and commutator energize in contact with each other and rotate, the brush includes a low-resistance conductive layer on a surface of a high-resistance substrate of the brush. The commutator motor forms an anisotropic conductivity in a direction directly going to a direction of a groove direction, achieves the good electrical conductivity and durability of the brush, and strikes a balance between the high efficiency and long operating life by forming a plurality of grooves with stripe shapes on the conductive layers on upper and lower surfaces that are parallel to a slide of the brush. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a commutator motor used for a household vacuum cleaner, a power tool, or the like.

  In recent years, commutator motors used for household vacuum cleaners and electric tools have been particularly reduced in size and capacity, and along with these, carbon brushes (hereinafter referred to as brushes) are also reduced in size. There is an increasing demand for low resistance loss and low wear.

  Conventionally, when a material having a high electrical conductivity is used for a brush for an AC commutator motor, there is a problem that although resistance loss is reduced, sparks are easily generated and wear of the brush is increased. On the other hand, when a material with low conductivity is used for the brush, it is difficult for sparks to be generated and wear can be suppressed, but resistance loss increases and temperature rises due to heat generation. Due to this temperature rise, there is a problem that the copper powder and lead copper wire used in the compression / bonding part where the lead copper wire is connected to the brush is oxidized and the conductivity is deteriorated, and the motor stops eventually. It was. As described above, in the commutator motor, it has been difficult to simultaneously achieve high efficiency and long life.

  Also, among brushes for AC commutator motors, high-speed motors such as those for electric vacuum cleaners have good commutation even at high-speed rotation and need to be replaced during the usable period of the vacuum cleaner body. It is necessary to have a long brush life so that there is no problem. As a countermeasure, a resin bond brush in which graphite powder is bonded with a resin binder and cured may be used. However, the resin-bonded brush has a problem that the conductivity of the brush body is small, and therefore, when the current density is increased, the temperature rises and the resin used for the binder deteriorates.

  As a publicly known example for solving the above-mentioned problem, Japanese Patent No. 3549279 discloses a brush in which a conductive layer having a resistance lower than that of the brush base material is provided on the side peripheral surface of the brush base material except for the side surface of the brush commutator outlet side. Is disclosed.

Japanese Patent No. 3549279

  However, in the case of the brush described in Japanese Patent No. 3549279, although the back side in the sliding direction is made high resistance by removing the conductive layer on the back side in the sliding direction of the brush, the brush parallel to the rotation direction of the commutator is used. Since the upper and lower surfaces are evenly electrically conductive layers, more charges are concentrated on the contact area with the commutator on the rear side in the sliding direction due to the action of the upper and lower conductive layers. There was a problem that sparks were likely to occur. For this reason, it was still difficult to achieve both high efficiency and long life of the commutator motor.

  The present invention has been made to solve the above-described problems, and provides a brush excellent in electrical conductivity and durability. Further, by providing the brush with excellent electrical conductivity and durability, a commutator motor that achieves both high efficiency and long life is realized.

The commutator motor according to the present invention is a commutator motor having a structure in which a brush and a commutator rotate by contact energization, and the brush substrate side surface excluding the brush commutator sliding surface and the back side surface in the sliding direction. A conductive layer having a lower resistance than the brush base material is applied to the surface, and a groove is formed from the commutator sliding surface side of the conductive layer applied to the upper and lower surfaces parallel to the sliding direction of the brush to the rear side surface side of the sliding direction. The commutator motor is characterized by being formed.
With the above configuration, the low resistance conductive layer on the upper and lower surfaces parallel to the sliding direction of the brush is divided by the groove, and the groove formed from the commutator sliding surface side of the conductive layer to the rear side surface of the sliding direction is further divided. Since current flows along the direction, anisotropic conductivity is formed in the direction perpendicular to the direction of the groove. By the above action, it is possible to prevent the concentration of electric charge on the contact part with the commutator on the back side in the sliding direction with high resistance without a conductive layer, and to prevent the occurrence of sparks during motor rotation and to suppress brush wear. It is possible to improve durability.
Further, according to the present invention, the distance between the groove formed between the sliding surface side of the conductive layer on the upper and lower surfaces of the brush in the sliding direction and the rear side surface in the sliding direction and the adjacent groove is such that the sliding portion of the brush and the commutator The commutator motor is characterized in that, in the portion where the contact is made, the distance between the child piece of the commutator and the adjacent child piece is smaller.
As described above, according to the present invention, it is possible to increase the current density at the front part in the sliding direction and decrease the current density at the rear part in the sliding direction. For this reason, it is possible to improve the durability of the brush while maintaining the electrical conductivity of the brush, and to realize a commutator motor with high efficiency and long life.

  According to the commutator motor according to the present invention, high efficiency and long life of the commutator motor can be realized.

It is a perspective view of the brush which concerns on embodiment of this invention. It is a perspective view which shows the attachment direction with respect to the rotation direction of the commutator of the brush used for the commutator motor which concerns on embodiment of this invention. The top view of the brush which shows the contact part of the brush and commutator which concerns on embodiment of this invention from a rotating shaft direction.

(Example)
Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is a perspective view of a brush according to an embodiment of the present invention.

As shown in FIG. 1, a brush 1 according to the present embodiment is made of a carbon brush base material such as artificial graphite, and an electrically conductive layer is applied to the front side surface 1 b in the sliding direction. No electrically conductive layer is provided on the sliding surface 1c and the rear side surface 1f in the sliding direction. The brush upper surface 1u and the lower surface 1d are provided with an electrically conductive layer, and a groove 6 is formed from the commutator sliding surface side to the rear side surface in the sliding direction. A pigtail 1a is attached to the brush end surface 1r.
In this embodiment, the electrically conductive layer is applied to the carbon brush substrate by plating. There are two methods for forming grooves in the upper and lower surfaces 1u and 1d: a method of masking when plating is performed, and a method of deleting after plating. Of course, the method of applying the conductive layer is not limited to plating, and various thin film forming techniques can be used.

  FIG. 2 is a perspective view showing an attachment direction of a brush used in the commutator motor according to the embodiment of the present invention with respect to the commutator rotation direction.

As shown in FIG. 2, a deformed tube 2 made of a conductive material encloses the brush 1 and welds the tip of the pigtail 1a to itself. The brush spring 3 is a spiral spring and is attached so that the pigtail 1a passes through the spiral space, and the brush 1 is pushed out of the deformed tube 2 by abutting both ends of the brush 1 and the deformed tube 2. Yes. The pigtail 1a is bundled by knitting a thin copper wire, etc., is flexible, has a sufficient length as shown in FIG. It is extruded from the deformed tube 2 and can be used continuously. Reference numeral 4 denotes a cage for holding the deformed tube 2, reference numeral 5 denotes a commutator, and a solid arrow indicates the direction of rotation of the commutator 5. A dotted arrow indicates the sliding direction of the brush 1. In the commutator motor of the present invention, the retainer 4 is attached to the commutator motor such that the upper surface 1u and the lower surface 1d formed with the groove 6 are horizontal with the sliding direction of the brush 1.
FIG. 3 is a top view of the brush showing the contact portion between the brush and the commutator according to the embodiment of the present invention from the direction of the rotation axis.

As shown in FIG. 3, the brush 1 and the commutator 5 are in contact with each other, and the commutator 5 is rotated. The solid line arrow indicates the direction of rotation of the commutator 5. Electrically conductive layers are applied to the upper surface 1u and the lower surface 1d, and a groove 6 is formed from the commutator sliding surface side to the rear side surface in the sliding direction. In this embodiment, the grooves 6 formed in the upper surface 1u and the lower surface 1d are formed in a plurality of stripes. Further, the interval w1 between the groove 6 and the adjacent groove is smaller than the interval w2 between the commutator piece 5a constituting the commutator 5 and the adjacent child piece at a portion where the brush and the commutator are in contact with each other.
In this way, since the current flows along the groove 6 of the conductive layer applied to the upper surface 1u and the lower surface 1d of the brush 1, anisotropic conductivity is formed in the direction perpendicular to the groove, and the rear side in the sliding direction Has a high resistance, and the front side in the sliding direction has a low resistance. As a result, the current density increases at the front part in the sliding direction, and the current density decreases at the rear part in the sliding direction. As a result, it is possible to prevent the occurrence of an arc generated between the brush and the commutator piece while maintaining the electrical conductivity of the brush, and to improve the durability of the brush.
In addition, by forming the grooves formed on the conductive layer into a plurality of stripes, the grooves extending from the commutator sliding surface side to the sliding direction rear side surface are maintained even if the brush length is shortened due to wear. The effect of the direction conductivity is also maintained.
In addition, the shape of the groove | channel provided in a conductive layer is not restricted to a linear shape like FIG. 3, A curved shape is also possible.
According to the configuration of the present invention described above, it is possible to simultaneously realize a long brush life while realizing high efficiency of the commutator motor.

  The brush and the commutator motor according to the present invention are useful for a brush capable of achieving both electrical conductivity and durability of the brush and a commutator motor using the brush.

DESCRIPTION OF SYMBOLS 1 Carbon brush 1a Pigtail 1b Sliding direction front side surface 1c Commutator sliding surface 1d Lower surface 1u Upper surface 1f Sliding direction rear side surface 1r End surface 2 Shaped tube 3 Brush spring 4 Cage 5 Commutator 5a Commutator piece 6 Groove w1 Energizing direction Interval between grooves at right angles w2 Interval between commutator pieces

Claims (2)

In the commutator motor that rotates when the brush and commutator are energized by contact,
A conductive layer having a lower resistance than the brush base material is applied to the side peripheral surface of the brush base material excluding the brush commutator sliding surface and the back side surface in the sliding direction,
A commutator motor, wherein a groove is formed from a commutator sliding surface side of a conductive layer provided on upper and lower surfaces parallel to a sliding direction of the brush to a rear side surface side of the sliding direction. In the portion where the gap between the groove formed adjacent to the groove on the upper and lower surfaces of the brush sliding direction from the sliding surface side of the conductive layer to the rear side surface in the sliding direction and the adjacent groove is in contact with the commutator, The commutator motor according to claim 1, wherein the commutator motor is smaller than an interval between a child piece of the commutator and an adjacent child piece.

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