GB2098467A

GB2098467A - Wiper mechanism

Info

Publication number: GB2098467A
Application number: GB8212690A
Authority: GB
Original assignee: Thales Optronics Ltd
Current assignee: Thales Optronics Ltd
Priority date: 1981-05-18
Filing date: 1982-04-30
Publication date: 1982-11-24

Abstract

A wiper mechanism (10) for cleaning a substantially circular surface (12) comprises an annular housing (11) surrounding surface (12) on which is mounted an annular carrier (15) and a drive means coupled to the carrier (15) for rotatably driving the carrier (15). A wiper arm assembly (20, 21) is mounted on the carrier (15) for engagement with the surface (12) to be cleaned and cleaning thereof is effected when the assembly (20, 21) extends substantially radial with respect to the carrier (15) and the carrier is rotated by the drive means. In one embodiment the assembly (20, 21) is always maintained radially with respect to the carrier (15) but in another embodiment the assembly (20, 21) is pivotally movable by means of a pin (19) so that it can be moved between an operative position which is radial with respect to the carrier (15) and an inoperative or parked position which is tangential with respect to the carrier (15). <IMAGE>

Description

SPECIFICATION Wiper mechanism This invention relates to a wiper mechanism.

Wiper mechanisms are known for use on motor vehicles, particularly for clearing dirt, rain and other impediments to visibility from the windscreen of the vehicle. Such mechanisms however do not clear the entirety of the windscreen and in fact because of the large area of such windscreens there is no requirement to do so. Recently wiper mechanisms have been introduced at the headlamps of motor vehicles but these have been mounted to clear the surface of a window secured to the bodywork and behind which the headlamp lens is mounted. This window is larger than the lens and accordingly permits the wiper mechanism to clear part only of the window.

The above described known wiper mechanisms are arranged for clearing generally rectangular surfaces and are either pivotal or linear reciprocal in their clearing action.

It is an object of the present invention to provide a wiper mechanism arranged for clearing a substantially circular surface such as is provided by a lens.

According to the present invention there is provided a wiper mechanism for clearing a substantially circular surface, comprising an annular housing for surrounding the surface to be cleared, an annular carrier mounted on the housing for rotation relative thereto, drive means for rotating the carrier, and a wiper arm assembly mounted on the carrier for engagement with said surface to effect clearing thereof when the assembly extends substantially radially with respect to the carrier.

Preferably the wiper arm assembly is pivotally mounted on the carrier so as to be pivotally movable between an in-use position when the assembly extends substantially radially with respect to the carrier and an out-of-use position when the assembly extends substantially tangentially to the carrier.

Preferably also the wiper arm assembly is pivotally mounted for movement towards and away from the plane of the annular carrier.

Conveniently the drive means comprises a motor driven pinion enmeshed with an annular ring gear coupled to said carrier. The coupling the between the carrier and the ring gear may be by means of pinions. Alternatively the drive means may incorporate a belt-drive arrangement.

Preferably also the wiper arm assembly includes an elongate wiper element which is curved along its length such that, in use, dirt and other impediments to visibility cleared from said surface are moved towards the circular periphery thereof.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figs. 1 and 2 illustrate a first embodiment in plan and part sectional side elevation; Figs. 3 and 4 are corresponding views of a second embodiment; Figs. 5 and 6 illustrate details of the second embodiment; and Figs. 7 and 8 illustrate modifications applicable to the second embodiment.

The wiper mechanism 10 of the first embodiment comprises an annular housing 11 which is dimensioned and arranged to surround the circular surface 12 to be cleared, surface 12 conveniently being an optical lens secured to a support 13. Housing 11 is of U-shaped section and thereby defines an annular channel 14 within which is located an annular carrier 15. The carrier 15 is mounted on bearings (not shown) so as to be rotatable relative to the housing 11 and is prevented from departing from channel 14 by an annular stop plate 16. Carrier 15 is generally of Lshaped section the base portion of which is provided with gear teeth 17 enmeshed with a motor-driven pinion 18 so that when pinion 18 rotates about its own axis the carrier 15 is rotated within the housing 11.The side portion of the carrier 15 is provided with a pin 19 which projects axially and to the end of which is secured a wiper arm 20 with wiper element 21, the latter being curved along its length as indicated in Fig.

1. Arm 20 in this embodiment is secured so as to maintain the position illustrated in Fig.1, that is substantially radially with respect to carrier 15.

The assembly comprising arm 20 and element 21 is pivotally mounted for movement about axis 22 towards and away from the plane of the carrier 15 and is biased against surface 12 by a spring 23 (shown schematically). Element 21 which is pivotally mounted on arm 20 comprises a semi rigid support member 24 carrying a resilient wiper blade 25 both being substantially conventional in construction and it will be noted that blade 25 extends from the circumferential periphery of surface 12 through the centre of the surface 12 in a curve as shown in Fig. 1 and also in a curve as shown in Fig. 2 in order to conform to the profile of surface 12.

In operation of this embodiment the motor driving pinion 18 is energised causing carrier 15 to rotate counter-clockwise in housing 11 thereby moving element 21 across the surface 12 in a circular motion. When the motor is de-energised the element 21 remains on the surface 12 and if so required this can be at a predetermined angular position.

In the second embodiment which is illustrated in Figs. 3-6 the mechanism is generally similar to that of the first embodiment but provision is made to move the element 21 (and arm 20) into a parked position when not is use so that the entirety of surface 12 is free of obstruction.

Features common to both embodiments will not therefore be further described in detail To provide the parking facility pin 19 is rotatably mounted on carrier 15 as shown in Fig.

4 and projects into chamber 14 where is terminates in a pinion 30. This pinion 30 is enmeshed with an idler pinion 31 mounted on carrier 15 and carrier 15 is made independent of gear teeth 17 by means of an interposed ring spacer 32. Carrier 1 5 however is driven by teeth 17 which form part of a ring gear by way of idler pinion 31 which is enmeshed with teeth 17. To accommodate spacer 32 it will be evident that chamber 14 requires to be enlarged somewhat and spacer 32 is secured to housing 11 by means of screws (not shown). In operation, when pinion 18 is driven by its drive motor (not shown) the ring gear comprising teeth 17 is rotated thereby rotating idler pinion 31 and pinion 30 so that arm 20 is rotated.In order to limit the extent of rotation of arm 20 pin 19 carries a radially projecting tongue 33 as shown in Fig. 6 which is movable only between two limit stops 34, 35, both mounted on carrier 15. Thus after initial counter-clockwise rotation of pinion 30 when tongue 33 abuts stop 35 the arm 20 is in the position shown in Fig. 3 (i.e. substantially radial to carrier 1 5) further counter-clockwise rotation of pinion 30 is prevented so that idler pinion 31 is prevented from rotation and so the teeth 17 bodily drive carrier 15 via pinion 31 in the counter-clockwise direction to effect clearing of the surface 12.When pinion 18 is halted arm 20 is returned to its parked position as indicated in phantom in Fig. 3, i.e. tangential to carrier 15, by means of spring 36 secured between pin 19 and carrier 1 5 or with the addition of a limited reverse drive to pinion 18.

The operation of the second embodiment is enhanced by arranging the polar moment of inertia of carrier 15 to be much greater than that of the arm 20 together with element 21 so that when the carrier 15 is made to rotate this ensures that the arm 20 and element 21 are caused to overcome the frictional forces between the surface 12 and the blade 25 until tongue 33 abuts stop 35 and that this position is maintained throughout operation of the mechanism. If this inertial difference is not sufficiently large this frictional force may not be overcome and the arm 20 may remain in an intermediate position resulting in incomplete clearing of surface 20.

Although surface 12 is illustrated as having a curved profile this need not be the case. However surface 12 may be spherical, aspherical or planar.

When surface 12 is curved in profile the end of arm 20 adjacent pin 19 may be provided with a stop 38 (Fig. 6) to limit the pivotal movement of arm 20 towards the surface 12 so that as the arm 20 moves from the parked position to the in-use position blade 25 is clear of surface 12 until the arm is approximately midway between its limiting positions. This therefore reduces the effect of frictional forces on movement of the arm 20, and therefore the inertical differences referred to above may be reduced. Also, short reversal of the drive motor followed by immediate forward drive has the effect of increasing the inertial difference so that arm 20 is able to overcome the effect of frictional forces more easily.

Although the described embodiments utilise gear drives throughout it will be evident that the main drive arrangement could be belt driven and, with regard to the second embodiment, the drive for pivotal movement of the wiper arm 20 could be effected by a cam and follower arrangement as shown in Fig. 7 or by a cam-operated link mechanism as shown in Fig. 8. Thus as shown in Fig. 7 cam plate 40 is carried by carrier 15 but has limited arcuate movement relative thereto and incorporates a camming slot 41 which is engaged by a follower 42 mounted on lever 43 which is secured to pin 19, the latter being rotatably mounted on carrier 15. With follower 42 in the illustrated position arm 20 (not shown) is in its operative position and when follower 42 is at the other end of slot 41 arm 20 is in its out-of-use position. As shown in Fig. 8 pin 19 is rotatably mounted in carrier 15 5 and secured to lever 45 the remote end of which is connected by link 46 to a member 47 mounted on the carrier 15.

It will now be evident that the wiper mechanism of the present invention permits clearing of the entirety of circular surface 12 and is a simple and compact mechanism. It is of use in clearing circular surfaces such as lens surfaces where the latter are made of a material or have a surface coating of good abrasion resistance.

Claims

1. A wiper mechanism for clearing a substantially circular surface, comprises an annular housing for surrounding the surface to be cleared, an annular carrier mounted on the housing for rotation relative thereto, drive means for rotating the carrier, and a wiper arm assembly mounted on the carrier for engagement with said surface to effect clearing thereof when the assembly extends substantially radially with respect to the carrier.

2. A mechanism as claimed in claim 1, wherein the wiper arm assembly is pivotally mounted on the carrier so as to be pivotally movable between an in-use position when the assembly extends substantially radially with respect to the carrier and an out-of-use position when the assembly extends substantially tangentially to the carrier.

3. A mechanism as claimed in claim 1 or claim 2, wherein the wiper arm assembly is pivotally mounted for movement towards and away from the plane of the annular carrier.

4. A mechanism as claimed in any preceding claim, wherein the wiper arm assembly includes an elongate wiper element which is curved along its length such that, in use, dirt and other impediments to visibility cleared from said surface are moved towards the circular periphery thereof.

5. A mechanism as claimed in any preceding claims, wherein the drive means comprises a motor driven pinion enmeshed with an annular ring gear coupled to said carrier.

6. A mechanism as claimed in claim 5, wherein the coupling between the carrier and the ring gear is by means of pinions.

7. A mechanism as claimed in any one of claims 1~4, wherein the drive means incorporate a belt-drive arrangement.

8. A wiper mechanism as claimed in claim 1 and substantially as hereinbefore described with reference to either of the embodiments illustrated in Figs. 1-6 of the drawings.

9. A wiper mechanism as claimed in claim 1 and substantially as hereinbefore described with reference to the embodiment illustrated in Figs.

3-6 of the drawings as modified by either of the modifications illustrated in Figs. 7 and 8 of the drawings.