GB2130476A - Windscreen wiper drive - Google Patents

Abstract

The aim of the invention is to provide an improved drive for windscreen and like wipers. A wiper arm 2 is mounted on a rotary spindle 3 carrying a pulley 5a or 5b. The pulley 5a is driven from a reciprocating drive 8, 9, itself driven by a motor 7, by means of a flexible tape 12 constrained within a channel 15 to provide a push-pull drive transmission. The pulley 5b is connected to the pulley 5a by means of a further flexible tape 21 running in a channel 22 to provide a push-pull drive transmission. The tapes 12 and 21 are shown as being provided with apertures 24 which cooperate with sprocket pins 5c on the pulleys 5a and 5b, but these may be omitted, and the tapes may be anchored directly to the pulleys 5a and 5b if required. <IMAGE>

Description

SPECIFICATION Windscreen wiper drive This invention relates to windscreen wiper drives. While the invention is primarily described with reference to the drives for windscreen wipers for passenger cars or other automotive vehicles, it will be appreciated that it is also usable on windscreens and other windows of other modes of transport, such as boats, hovercraft, aircraft, cranes and earthmoving equipment, as well as on the windows, other than windscreens, of all such vehicles or modes of transport.

Conventionally, the drive for a rotationally reciprocable windscreen wiper blade is transmitted from a drive motor via a crank and lever mechanism which tends to be heavy and to require careful adjustment and maintenance.

In accordance with a first aspect of the present invention, there is provided a drive mechanism for a wiper arm for a windscreen or the like, in which the wiper arm is mounted on a rotary spindle drivable in a rotary reciprocation by means of a flexible tape constrained by a guide channel to operate as a push-pull drive transmission.

The tape may be driven by a slide in rectilinear reciprocation and a second wiper arm may be driven from the rotary spindle by means of a further flexible tape constrained by a guide channel to act as a push-pull transmission.

In accordance with a second aspect of the invention, there is provided a wiper arm assembly for a windscreen or the like having a drive mechanism according to the invention as set forth above.

The drive mechanism assembly in accordance with the invention is lighter than a conventional arrangement and is also more versatile in installation. The use of heavy steel or other lever mechanisms is also avoided.

The invention will be further described with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an elevational view of a preferred form of drive mechanism in accordance with the invention, in association with other related parts; Figure 2 is an enlarged and exploded view illustrating part of the drive; and Figure 3 illustrates the attachment of a modified form of tape to a pulley wheel.

Turning first to Fig. 1, windscreen wiper blades are illustrated at 1 as being mounted on wiper arms 2. The wiper arms 2 are mounted on rotary spindles 3 extending through housings 4, and carrying at their opposite ends pulleys or wheels 5a and 5b.

Mounting brackets 6 for the housings 4 are also illustrated in Fig. 1.

A generally conventional drive motor 7 drives a crank arm 8 in rotation, and this, via a link 9, drives a slide 10 (see Fig. 2) constrained by a slide block 11 in rectilinear reciprocation The slide 10 is attached to a flexible tape 12 by means of screws 13 and a clamping plate 14. The tape 12 has a degree of flexibility to enable it to conform to the periphery of the pulley 5a, but it runs with its edge areas located within and constrained by lateral extension 14 of a guide channel 15. The tape 12 is thus prevented from cockling significantly when in compression and thus can transmit drive in both push and pull modes.

The slide block 11 is mounted on a mounting plate 16 which also carries the motor 7, and the slide 10 is also constrained within the slide block by means of a removable cover which is secured by screws 17.

One end of the channel 15 is received within a recess 18 in the slide block 11, and secured in any suitable manner, and the other end of the channel 15 is formed into substantial conformity and in close proximity with the outer periphery of the pulley 5a over a substantial but minor arc thereof. The periphery of the pulley 5a is provided with sprocket pins not specificially illustrated, but similar to those illustrated on the pulley 5b by the reference numeral 5c. These sprocket pins 5c are circumferentially pitched so as to engage correspondingly longitudinally pitched apertures 24 in the tape 12 to provide a driving connection between the tape 12 and the pulley 5a.The remote end of the tape 12 may also be anchored to the pulley 5a by means of screws and an arcuate clamping plate if desired.

The pulley 5a is thus drivably connected to the slide 12 so as to be driven in rotational reciprocation by the motor 7.

This motion of course provides the desired motion of the wiper arm 2 and the wiper blade 1.

In order to drive the second wiper arm and blade by means of the pulley 5b, a second flexible tape 21 running in and constrained by a channel 22 similar to channel 15 is provided. The channel 22 extends round a further minor arc of the pulley 5a so as to constrain the tape 21, and it also extends over substantially a semi-circular arc of the pulley 5b. One end of the tape 21 cooperates by means of the aperture 24 with the pins 5c on the pulley 5a and may also be secured by means of screws and an arcuate clamping plate. The other end of the tape 21 is shown by the reference numeral 23 as being free, after having passed around the semi-circular arc of the pulley 5b within the channel 22 with its apertures 24 in cooperation with the pins 5c.The free end 23 may of course also be anchored to the pulley 5b if required.

The pulley 5b is thus entrained in the reciprocal rotation of the pulley 5a so that both the wiper blades 1 and wiper arms 2 move in unison.

Fig. 3 shows an arrangement in which a plain rather than perforated tape 21 a is used to cooperate with a flat outer periphery of a pulley shown at 5aa. In such a case, the tape 21 a needs to be anchored securely to the pulley 5aa, and this is shown as being achieved by means of a clamping plate 25 and a group of bolts 26. Where a plain tape 21 is used, the tape 15 will also normally be plain and anchored by a similar arrangement to the pulley 5aa. The tape 21a will have its opposite end also anchored to a corresponding second pulley.

The flexible tapes 12 and 21 may either be of metal or a suitable plastics material or even a combination if required. The channels 15 and 22 may also be either metal or a suitable plastics material.

A further advantage of the invention is that a single type of drive mechanism 7, 8, 9, 11 may be used to give varying angles of wipe by choosing pulleys 5a, 5b of appropriate diameter. This design option is more difficult to achieve with conventional lever drives.

Various modifications may be made within the scope of the invention.

Claims (8)

1. A drive mechanism for a wiper arm for a windscreen or the like, which the wiper arm is mounted on a rotary spindle drivable in a rotary reciprocation by means of a flexible tape constrained by a guide channel to operate as a push-pull drive transmission.

2. A drive mechanism as claimed in claim 1, in which the tape is driven by a slide in rectilinear reciprocation, the slide being driven by a rotary drive motor.

3. A drive mechanism as claimed in claim 2, including a second wiper arm having a rotary spindle connected to the said rotary spindle by a further flexible tape.

4. A drive mechanism as claimed in claim 3, in which the said further flexible tape is also constrained by a guide channel to operate as a push-pull drive transmission.

5. A drive mechanism as claimed in any of the preceding claims, in which the said flexible tape is perforated at regular pitching to cooperate with sprocket pins on a pulley on the rotary spindle.

6. A drive mechanism as claimed in any of claims 1 to 4, in which the flexible tape is releasably anchored to a pulley on the rotary spindle.

7. A wiper arm assembly for a windscreen or the like having a drive mechanism as claimed in any of the preceding claims.

8. A drive mechanism for a wiper arm substantially as hereinbefore described with reference to the accompanying drawings.