JPS598456Y2 - commutator - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to the structure of a commutator for a rotating electric machine.

It is desirable that the commutator of a rotating electric machine has as short an axial length as possible.

FIG. 1 is a longitudinal sectional view showing the structure of a conventional commutator.

A predetermined number of commutator pieces 1 made of drawn hard copper having a thin trapezoidal cross section are stacked alternately in the circumferential direction with insulation between the pieces, to form a commutator cylinder.

Both axial end faces of this commutator cylinder are cut into a substantially V-shape to form an annular ■-shaped concave groove.

The holding body 4 and the annular convex portion of the push ring 5 having a ■-shaped cross section are engaged with this concave groove via the ■-shaped insulating mica rings 2 and 3, and are pressurized in the axial direction to form a commutator. .

In this case, the ■-shaped insulating rings 2 and 3 are the commutator piece 1 and the holder 4.
In order to ensure creepage insulation distance between the push ring 5 and the push ring 5, and to maintain safe insulation against contamination caused by carbon abrasion powder, it is necessary to protrude from the commutator piece in the axial direction and provide a sufficient distance. Therefore, the axial lengths of the holding body 4 and push ring 5 also become longer.

■Increasing the axial length of the shaped insulating ring requires a large amount of expensive mechanical force and increases the number of man-hours, which not only increases the cost of the commutator but also increases the axial length of the commutator.
As a result, the axial length of the rotating electric machine becomes long, which has the drawback of increasing the price of the rotating electric machine.

FIG. 2 is a longitudinal sectional view of a conventional commutator with a different structure.

As in the case of the example shown in Fig. 1, a predetermined number of commutator pieces 1 made of drawn hard copper having a thin trapezoidal cross section are stacked alternately in the circumferential direction with insulation between the pieces to form a commutator cylinder. Ru.

This commutator cylinder has both end faces in the axial direction cut into a U-shape, reinforcing rings 6 and 7 are interposed in the annular U-shaped groove, and the space between it and the holder 8 is integrally molded with an insulating resin 9. This is a so-called molded commutator.

In this structure, a creeping distance can be obtained in the direction perpendicular to the axis at the end face of the insulating resin 9 of the molded part, so that the axial length is shortened.

However, in order to prevent vibrations during rotation, it is necessary for rotating electric machines to achieve so-called dynamic balance, and this is usually achieved by balancing both sides of the rotor in the axial direction. It is common practice to use a holder or the like on the outer end surface of the child in the axial direction, and make screw holes in it to screw the heavy piece as appropriate, or to drill holes according to the amount of imbalance. However, it is necessary that the position for achieving balance be a certain distance from the rotation axis.

For this reason, the diameter of one axially outer end of the holding body 8 is increased, and a threaded hole 10 for balance correction is provided in that portion to attach a bolt or the like.

For this reason, the insulation distance between the commutator piece and the holder becomes small in this part, so in order to increase the creepage insulation distance, the end 91 of the insulating resin 9 is extended in the axial direction. There is a drawback that the axial length becomes long.

It is an object of the present invention to provide a commutator which eliminates the above-mentioned drawbacks, secures a sufficient creepage distance in a simple manner, and reduces axial beads.

Next, an embodiment of the present invention will be explained with reference to the drawings.

FIG. 3 is a longitudinal sectional view of a commutator according to an embodiment of the present invention.

Reference numerals 1 to 5 are the same as in FIG. 1, but V-shaped insulating ring 2
, 3 holder 4 and press ring 5 have shorter portions that protrude in the axial direction from one end surface of the commutator.

An insulating cylinder 11 having a flange portion on one side as shown in FIG. The outer periphery of the cylindrical portion is heated and tightened with a heat-shrinkable insulator 12 to fix it.

A suitable heat-shrinkable insulator is, for example, terephthalate polyester resin.

The insulating tube 11 has a flange portion 111 at one end, and the inner diameter of the cylindrical portion 11 is slightly larger than the outer diameter of the portion of the V-shaped insulating rings 2 and 3 that protrudes from the commutator pieces, and this portion is loosely connected. The cylindrical portion 11 is designed to fit in, and the axial length of the cylindrical portion 11 may be sufficient to provide a restraint for maintaining the posture during assembly.

The insulating tube 11 is formed into one piece by hot drawing or the like more easily than a thin hard insulating material such as a terephthalic acid polyester resin film having good electrical insulation properties, and its manufacturing cost is extremely low.

Due to the presence of the flange portion 111, the front surface and the back surface act as a creepage insulation distance, resulting in better insulation performance than before.Furthermore, a centrifugal air flow is generated along the front surface and the back surface of the flange portion. It works to scatter brush abrasion powder in and around the area more quickly, and as a result, the accumulation of abrasion powder is drastically reduced.

FIG. 5 is a longitudinal sectional view of a commutator according to another embodiment of the present invention.

This corresponds to FIG. 2, and numerals 1 to 10 are the same as in FIG.

The axial length of the protruding portion 91 of the insulating resin 9 from the commutator piece is shorter than that in FIG. 2.

A flanged insulating tube 11 is fitted into this protrusion 91 in the same manner as in the embodiment shown in FIG. 3, and its outer periphery is fixed by heating and tightening with a heat-shrinkable insulator 12.

According to the present invention, the insulation creepage distance of the commutator can be set in a direction perpendicular to the axis using inexpensive members and by a simple method, so the axial length of the commutator can be shortened, and the axis of the entire rotating electric machine can be shortened. Not only does the reduction in length in the direction reduce the size and weight, which has the effect of reducing costs, but it also dramatically reduces the accumulation of brush abrasion powder around the flange, making it easier to clean in the event of a commutator failure. This has the effect of allowing replacement and repair of the insulating tube equipped with the flange.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views showing the structure of a conventional commutator, 3 and 5 are longitudinal sectional views of a commutator according to an embodiment of the present invention, and 4 is a longitudinal sectional view showing the structure of a conventional commutator. FIG. 3 is a perspective view of an insulating tube. 1: Rectifier piece, 2.3: V-shaped insulation ring, 4: Holder,
5: Push ring, 6, 7: Reinforcement ring, 8: Holder, 9: Insulating resin, 10: Balance correction hole, 11: Insulating tube, 12
: Heat-shrinkable insulation.

Claims (1)

[Scope of utility model registration request] In a commutator in which a commutator cylinder formed by alternately overlapping commutator pieces and inter-piece insulation in the circumferential direction is fixed to a holder via an insulator, a commutator that protrudes in the axial direction than the commutator pieces. A substantially cylindrical portion is formed on the insulator, and the flange portion of the insulating cylinder is formed on one side opposite to the commutator, and the cylindrical portion is formed on the outer periphery of the cylindrical portion of the insulator. A commutator characterized in that the insulating tube is fitted into the cylindrical portion of the insulating tube, and a heat-shrinkable insulating tube is placed over the outer periphery of the cylindrical portion of the insulating tube to tightly bind and fix the insulating tube to the cylindrical portion of the insulating material.