Electrical drive unit

Details Electrical drive unit Electrical drive unit

1999-02-26

2000-12-19

Ramirez, Nestor

Electrical generator or motor structure

Dynamoelectric

Rotary

310242, 310 42, H01R 3938, H02K 1500

Patent

active

061630969

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention relates to an electrical drive unit, in particular for windshield wipers of a motor vehicle, including a drive motor which has an armature accommodated in a substantially cup-shaped pole housing, and a substantially cup-shaped gearbox for receiving gear elements which is secured on its face end to the motor housing and is closable by a gearbox cover.
Such electric switch elements are known for instance from German Patent Disclosures DE 32 20 191 A1 and DE 32 35 622 A1, German Patent DE 39 30 144 C2, and German Patent Disclosure DE 41 16 100 A1.
A problematic aspect of these drive units is the relatively complicated and hence expensive assembly of many separate individual parts. In particular, assembling the various prefabricated component units or individual parts requires a great many joining directions. Mounting the brushes contacting the commutator proves to be especially problematic. In the known devices, these brushes are secured to annular brush holder supports that surround the motor shaft. Since the brushes must rest on the commutator with a certain contact pressure, it is necessary in mounting the brushes to push them outward somewhat in the radial direction and to keep them in that position, so that the motor shaft together with the commutator can be introduced into the opening, with the brushes pushed back. Not only does this complicated mode of assembly require some skill; it is also a hindrance, especially to assembling the electrical drive unit by machine.
It is therefore the object of the invention to refine an electrical drive unit of the generic type defined above in such a way that it has the simplest possible design, thus enabling the simplest possible assembly of the fewest possible parts or prefabricated component units.


ADVANTAGES OF THE INVENTION

According to the invention, this object is attained, in an electrical drive unit of the type defined at the outset, in that a closable opening is provided in the gearbox or pole housing, through which opening a brush holder support that holds commutator brushes can be pushed in the radial direction onto the commutator.
The opening in the pole housing or gearbox, through which a brush holder support that holds commutator brushes can be pushed radially onto the commutator, has the especially great advantage that inconveniently introducing the commutator into the bushes, disposed on a ring and held in a retracted position, as described above, can be dispensed with entirely. Instead, by means of the brush holder support, all the brushes can be pushed radially onto the commutator simultaneously, thus enabling lateral mounting of the commutator brushes, and in particular together with the lateral mounting of the gear elements. Moreover, securing the commutator brushes in this way also enables easy dismantling, for instance if the commutator brushes are worn. It is also especially advantageous that to mount the complete drive unit, only two joining directions are needed, namely one in the axial direction of the motor shaft and one perpendicular to the axial direction of the motor shaft.
Purely in principle, the opening may be disposed either in the gearbox or in the pole housing or even between the two. For instance, it may be provided in the pole housing and can be closable by a separate cover.
For the sake of very simple mounting, however, it is especially advantageous that the opening is disposed in the gearbox and is closable together with it by the gearbox cover.
To enable rpm-dependent triggering of the drive motor, in particular, it is provided in an advantageous embodiment that a ring magnet secured to a motor shaft is disposed in the opening, and its rotary position is detected by magnet sensors that are disposed on circuits secured to the inside of the gearbox cover. Because of this disposition, the magnet sensors can be mounted in a simple way and aligned precisely on tie ring magnets, thus making exact yet simple detection of the rotary position of the shaft of the drive motor possible.
Especially with a view

REFERENCES:
patent: 4398135 (1983-08-01), Busch et al.
patent: 4585968 (1986-04-01), Cambrodon
patent: 5485049 (1996-01-01), Shannon et al.
patent: 5493220 (1986-06-01), Cousins et al.
patent: 5594290 (1997-01-01), Shannon et al.
patent: 5656878 (1997-08-01), Nakata

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