Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1984-03-22
1985-12-17
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310246, 310247, H02K 1300
Patent
active
045594651
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a brush holder and to an electric motor provided with such a brush holder.
In numerous types of electric motors the electrical continuity between the rotating armature and the fixed circuit connected thereto is ensured by co-operation between a commutator mounted on the rotor, and brushes, particularly of the carbon type, held by a brush holder so as to make contact with the rotating commutator.
In view of the wear of the brushes and the manufacturing tolerances, it is essential that the brushes be pushed resiliently against the commutator. Consequently, during operations involving assembly and disassembly of such motors, when the commutator is not positioned between the brushes, the brushes tend to be driven out of the housings in which they can slide, by the devices which normally push them back towards the commutator. As a result, the assembly of a motor constitutes an awkward operation, particularly if there is a large number of brushes.
U.S. Pat. No. 4,163,167 describes a brush holder ,hich does not have the above-mentioned disadvantage. In fact, the brush holder described in that patent comprises a support means having a central opening for the passage of a motor commutator and including two housings of rectangular cross-section permitting two brushes to slide in an approximately radial direction. Each brush has a rectangular cross-section and its radially outer end face is inclined slightly towards one side. Studs fixed on the support means each have a spring comprising, a hook arm fixed on a projection of the support means and a biasing arm which normally pushes the associated brush towards the central opening for the commutator, the biasing arm acting by resting against the slightly inclined end face. According to that patent, the lateral face of the brush has a small notch which faces towards the biasing arm of the spring, and the arm of the spring is sufficiently long for the end of the spring arm to leave the end face and come against the lateral face when the brushes are pushed back towards the exterior to a maximum. The spring thus exerts a force perpendicular to the sliding direction of the brush which is consequently jammed against the wall of its housing and cannot slide towards the centre.
This device for holding brushes in an outer or retracted position is perfectly satisfactory. Before assembly of the motor, the brushes are pushed outwardly manually so that the associated springs hold them in these positions. After assembly of the commutator, the brushes require only a slight push inwardly to enable them to return to the interior. The end of the spring arm leaves the notch formed on the lateral face and comes to rest against the end face. From this moment, the spring pushes the corresponding brush back towards the commutator
However, the described device has disadvantages. In fact, the support means is very complicated as it has to form a housing of rectangular cross-section for the sliding of each brush and has to comprise a projection for hooking the end of the spring opposite the biasing arm. Moreover, the support requires studs to hold the springs in a suitable position. Consequently, the brush holder support means is very expensive and is awkward to produce. Furthermore, this brush holder is quite bulky and is therefore unsuitable for small sized motors, particularly for control for automobile accessories.
The invention relates to a brush holder which has the advantageous characteristic of holding both brushes in the outer or retracted position by means of the spring which is normally used for pushing the brush towards the commutator. However, the brush holder support means according to the invention is extremely simple and inexpensive to produce. More specifically, it is formed as a single part cut from a flat plate. The support means does not have to meet close tolerances and no further operation is required after cutting, for example by stamping.
In particular, the invention relates to a brush holder comprising:
a support means having an opening
REFERENCES:
patent: 3138728 (1964-06-01), Videtic
patent: 3182218 (1965-05-01), Videtic
patent: 4112321 (1978-09-01), Wan
patent: 4163167 (1979-07-01), Zelt et al.
Equipements Automobiles Marshall
Skudy R.
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