1. Field of the Invention
This invention relates generally to a brush holding device, and more particularly to a brush holding device for holding a brush for making electrical contact with a commutator of a small electric motor.
2. Description of the Prior Art
In a small electric motor, brushes for making electrical contact with commutators are resiliently supported by brush holding plates made of a resilient, electrically conductive material and electrically connected to the brush holding plates. In this type of brush holding device having a brush holding plate, which is constructed so as to hold the top of a brush in position by the resiliency of lanced and raised pieces, damages are often caused to the top of the brush. That is, lanced and raised pieces of an L-shaped cross section are provided as a means for holding a brush on a brush holding plate by lancing and raising a part of the brush holding plate made of an electrically conductive, resilient material, and the brush is held in position between the edges of the lanced and raised pieces by forcing the brush in between the lanced and raised pieces. This construction often causes the edges of the lanced and raised pieces to cut into the engaging surfaces of the brush which is usually of brittle nature, resulting in damages to the top of the brush. On the other hand, to reduce the contact pressure of the brush to the commutators, the recent trend is toward the use of thinner materials for the brush holding plate, and consequently toward the increased width of the brush holding plate to increase the mechanical strength of the brush holding plate itself. However, an excessive increase in the width of the brush holding plate relative to the width of the brush proper is not desirable in terms of limited space inside the motor. It is necessary, therefore, to devise an effective means for holding a brush on a brush holding plate while maintaining the mechanical strength of the brush holding plate itself.