This invention relates to a combined planetary and worm gear drive for an automobile windscreen wiper system.

It is an object of this invention to propose a combined planetary and worm gear drive to provide a large speed reduction ratio, high rotational speed and structural compactness.

The windscreen wiper system, with combined planetary and worm gear drive, for an automobile, comprising a d.c. motor, a wiper blade and rotary link assembly, characterized by a planetary gear having an input shaft coupled coaxially to the said motor, and an output shaft provided with a worm profile; a worm wheel engaging with the said worm profile perpendicularly to the said output shaft of the planetary gear, the rotary link of the said assembly being mounted on the output shaft of the said worm wheel for actuating the wiper blades of the said assembly, reciprocatingly.

The various features of this invention will be apparent from the following further description given hereunder with reference to the accompanying drawings which illustrate, by way of example, and not by way of limitation, one of its various possible embodiments,

Fig.1 illustrating a front view, shown in isolation, of a wiper motor of the embodiment.

Fig.2 illustrating a sectional view of the motor taken along a line
A-A in Fig. 1 And

Fig. 3 illustrating a sectional view of the motor taken along a line B-B in Fig. 1.

The embodiment relates to a planetary gear 29 and worm gear 30. A wiper motor 33 has an electric direct current motor 28 which rotates a rotary link 31 through a planetary gear 29 which is axially assembled to motor 28 and a worm gear 30 which is assembled perpendicular to planetary gear 29 to effect movement of the wiper blades. The rotary link 31 is assembled to arm and blade assembly through a four bar linkage.

The planetary gear 29 reduces the speed of rotation of the direct current electric motor input shaft 10 and worm gear 19 for reducing the speed of rotation of the planetary gear output shaft 17. A rotor in which an armature 7 and a commutator 5 are fixed to a rotary shaft 10, the brushes 4 are in contact with the commutator peripheral surface 5 a and the other end of a rotary shaft 10 is having a sun gear 10a. A motor includes a cylindrical yoke 6 which is placed between brush plate housing 1 and gear wheel housing 18 and magnets 8 are assembled on yoke 6. The motor comprises a brush plate 3 which is assembled on the brush plate housing 1. The bush 2 which is press fitted with the brush plate housing 1 engages with an input shaft 10. The direct current electric motor 28 includes a through bolt 9 which is used to assemble brush plate housing 1 and gear wheel housing 18.

Planetary gear output shaft 17 is having a worm thread profile 17a. Planetary gear output shaft 17 accomodates one end of rotary input shaft 10, bush 34 is press fitted in the output shaft 17, ball 16 is placed at end of input shaft 10 and output pins 14 are press fitted on output shaft 17, the other end of output shaft 17 engages with third end screw 21. Third end surface of planetary gear output shaft 17 b is engaged with bush 20 which is press fitted in the gear wheel housing 18.

Gear wheel housing 18 includes an annulus 12 which is press fitted in the gear wheel housing 18, third end screw 21 is assembled on gear wheel housing 18 to guide the rotation of planetary gear output shaft 17, bushes 15, 20 are fitted on both sides of gear wheel housing 18 to withstand the loads acting on the planetary gear output shaft 17, worm wheel 19 is accommodated inside the gear wheel housing 18, two bushes 25, 25a are press fitted on gear wheel housing and one bush 25b is press fitted on cover plate 26 to withstand the loads acting on the gear wheel output shaft 19a, mounting lugs 18a of gear wheel housing 18 is assembled on mounting plate.

Worm wheel output shaft 19a is assembled at right angle to planetary gear output shaft 17. It's one end is assembled to a rotary link 31 and it's other end is guided by cover plate 26. Planetary drive 29 comprises a planetary gear cover plate 11 which is assembled between worm gear wheel housing 18 and yoke 6. A rubber seal 24, washer 23 are arrested using circlip and cover seal 22 is placed on rotary link end of worm gear wheel housing 18 to avoid water, dust entry.

Worm wheel cover plate 26 is assembled on the worm gear wheel housing 18 and bush 25b is press fitted inside the worm wheel cover plate 26. The switch fingers 35 are moulded with worm wheel cover plate 26. The slip ring 36 is assembled on worm wheel 19. The seal 37 is assembled between worm wheel housing 18 and worm wheel cover plate 26. Connecting wires 38 from switch finger 35 and brush plate 3 are assembled to the connector 39.

It will be appreciated that various other embodiments of this invention are possible without departing from the scope and ambit of this invention.

We Claim:

1. A windscreen wiper system, with combined planetary and worm gear drive, for an automobile, comprising a d.c. motor, a wiper blade and rotary link assembly, characterized by a planetary gear having an input shaft coupled coaxially to the said motor, and an output shaft provided with a worm profile; a worm wheel engaging with the said worm profile perpendicularly to the said output shaft of the planetary gear, the rotary link of the said assembly being mounted on the output shaft of the said worm wheel for actuating the wiper blades of the said assembly, reciprocatingly.

2. A wind screen wiper system as claimed in claim 1 wherein the rotor of the said motor is fixed to a rotary shaft, the other end of which has a sun gear.

3. A wind screen wiper system as claimed in claim 1 wherein switch fingers are moulded with the worm wheel cover plate.

4. A windscreen wiper system, with combined planetary and worm gear drive, for an automobile, substantially as herein described and illustrated.