GB1590316A - Wiper device for the windscreens of motor vehicles - Google Patents

Description

(54) WIPER DEVICE FOR THE WINDSCREENS OF MOTOR VEHICLES (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a windscreen wiper device.

A wiper device is known which comprises a rotatable drive crank on which a connecting rod is articulated. The other end of the connecting rod is pivotally attached to a component operatively connected to a shaft wheel firmly mounted on a driver or wiper shaft. The known wiper device is constructed such that, in order to achieve a relatively large wiping angle, the component which is operatively connected to the shaft wheel on the wiper shaft is a segment of a toothed wheel, which meshes with toothing of the shaft wheel, the toothed wheel being driven in an oscillatory manner by the connecting rod. In this wiper device the possible transmission ratio is exclusively determined by the ratio of the crank lever arm to the lever arm of the tooth segment, whereby the construction of the wiper device with a lever-pendulum drive allows only a certain maximum oscillatory angle. Furthermore the known wiper device is of relatively large construction, which can lead to difficulties of mounting in view of the low availability of space in motor vehicles.

According to the present invention there is provided a wiper device for the windscreens of motor vehicles, the device comprising a rotatable drive crank, a connecting rod articulated at one end to the drive crank and connected pivotally by its other end to the axis of a rotatable wheel operatively connected to a shaft wheel firmly mounted on a wiper shaft by means which transmit peripheral forces, the rotatable wheel having a greater diameter than the shaft wheel, means being provided for guiding the rotatable wheel about the shaft wheel over a predetermined angle along a path fixed relative to a housing of the device.

The wiper device in accordance with the invention has by way of comparison with known devices the advantage that it makes possible a method of construction which is considerably more compact and easier to assemble. Furthermore an oscillatory angle of more than 40 can be attained without difficulties by means of the wiper device in accordance with the invention. The wiper device in accordance with the invention possesses as a further advantage, in comparison to the known wiper device, in having one less bearing, which in addition to a considerable simplification of construction and assembly also contributes to an improvement in the operating safety of the wiper device.

The invention will hereinafter be further described by way of example with reference to the accompanying drawings in which: Figure 1 is a partial view of a wiper device in accordance with the invention in which a toothed wheel which meshes with the shaft wheel is mounted on the connecting rod, and Figure 2 is a partial view of a different embodiment of the invention in which a dual pulley wheel, whose operation is connected by way of drawing means to the shaft wheel, is mounted on the connecting rod.

The wiper device 10 shown in Figure 1 has a drive shaft 12, which rotates in the direction of the arrow 11, to which a crank 13 is firmly connected. A connecting rod 14 is articulated at the free end of the crank 13 by one of its ends and a toothed wheel 15 is mounted at the other end. The toothed wheel 15 meshes with a cam 16 with internal toothing, which to a certain extent represents a curved toothed rack. The cam 16 is located concentrically about a driven or wiper shaft 17 which is firmly connected to a shaft wheel or pinion 18. The toothed wheel 15 also meshes with the pinion 18. The cam 16 with internal toothing is firmly connected to a housing part 19, belonging to the wiper device. A plate 20 is mounted on each side of the pinion 18 on the wiper shaft 17 so as to be able to oscillate and is also guided by its other end at the bearing 21 of the toothed wheel 15 on the connecting rod 14.

When during the operation of the wiper device 10 the crank 13 is rotating in the direction of the arrow 11, the connecting rod 14 is moved in the direction of the double-headed arrow 22. As both the cam 16 with internal toothing and the pinion 18 form guide ways for the toothed wheel 15, articulated on the connecting rod 14, the toothed wheel 15 is guided according to the displacement movement, communicated to it, on a path (double-headed arrow 23) which is concentric to the wiper shaft 17.

Due to the fact that the toothed wheel 15 meshes with the curved frame-fast toothed rack 16, a rotary movement (double headed arrow 24) of the toothed wheel 15 is produced by the displacement movement 23 and transmitted to the pinion 18 and the wiper shaft 17. According to the transmission ratio between the toothed wheel 15 and the pinion 18 the oscillatory angle, which the toothed wheel describes on its cam path 23, is translated to the pinion 18 and transmitted by it to the wiper shaft 17 (double-headed arrow 25). The cover plates 20 oscillate together with the toothed wheel 15 and the wiper shaft 17, whereby they contribute to an orderly guiding of the toothed wheel 15 between the toothed rack 16 and the pinion 18.

The embodiment of the wiper device 30 in accordance with the invention, which is shown in Figure 2, also has a drive shaft 12 which rotates in the direction of the arrow 11 and is provided with the crank 13. In contrast to the first embodiment, in the case of the second embodiment a dual pulley wheel 31 is mounted at the end of the connecting rod 14, remote from the crank 13, whose one pulley 32 has a coaxial projection 33 which forms the other cable pulley. Furthermore a wiper shaft 35 is mounted in a housing part 34 of the wiper device 30 and is firmly connected to a shaft wheel 36, constructed as a cable roller. At least one rocker arm 37 is mounted on the wiper shaft 55 so as to be able to oscillate and its free end is guided at the bearing 38 of the double cable roller 31 on the connecting rod 14. The rocker arm 37 serves as a support and a spacer for the double cable wheel 31 relative to the wiper shaft 35. The ends 41 of a guide member 40, constructed as a toothed belt, are anchored at the periphery of a projection 39 of the housing, concentric to the wiper shaft 35, the guide member being at least partially looped about the smaller roller 33 of the double cable wheel 31. The length of the toothed belt 40 is set in such a manner that it is tautly stretched and forms a guide way for the double cable wheel 31, on which the smaller roller 33 is guided as it unrolls. The larger roller 32 of the double cable wheel 31 is connected in its operation to the shaft wheel 36 by way of a continuous toothed belt 42 which works as a drawing means.

When the wiper device as shown in Figure 2 is in operation the crank 13 rotates in the direction of the arrow 11. The connecting rod 14 is thereby displaced in the direction of the double-headed arrow 43, whereby the double cable wheel 31 is displaced along a guide way (Double-headed arrow 44) deter; mined by the toothed belt 40. The support 37 serves for an orderly cooperation between the toothed belt and the smaller roller 33 of the double cable wheel 31 and oscillates corresponding to the movement 43 of the connecting rod 14 about the wiper shaft 35. Because the guide member 40 is framefast anchored, the smaller roller 33 of the double-cable wheel 31 unrolls on this framefast guide way and oscillates together with the larger roller 32 of the double cable wheel 31 according to the double-headed arrow 45 in the bearing 38. This oscillatory movement 45 is transmitted by means of the toothed belt 42 to the shaft wheel 36 and the wiper shaft 35 so that the wiper shaft 35 in set in an oscillatory movement according to the double-headed arrow 46. As, however, the cable wheel 36 is of considerably smaller diameter than the large roller 32 of the double cable wheel 31, a corresponding transmission between these two components occurs so that the oscillatory angle of the wiper shaft 35 is considerably greater that that of the double cable wheel 31 in the bearing 38. The curvature of the projection 39 of the housing causes the toothed belt 40 to adhere cleanly during the oscillatory movement of the double cable wheel 31 so that the mechanical loading of the toothed belt 40 in the region of its anchored ends 41 can be kept small.

Both embodiments described have as a common feature that in each case a rotatable wheel 15 and 31 respectively is mounted at the free end of the connecting rod 14, the diameter of which wheel is greater that the diameter of the shaft wheel 18 and 36 respectively, which is firmly connected to the wiper shaft 17 and 35 respectively. Furthermore in both cases the wheel 15 and 32 respectively, connected to the connecting rod 14, has means through which its operation is connected to the shaft wheel 18 and 36 respectively. These means are formed in the case of the embodiment in Figure 1 by the teeth of the toothed wheel 15 and the teeth of the pinion 18 and in the case of the embodiment in Figure 2 by drawing means 42. Furthermore in both cases the wheel 15 and 32 respectively, mounted on the connecting rod 14, is guided about the shaft wheel 18 and 36 respectively over a certain angle along a frame-fast path 16 and 40 respectively.

By means of appropriate coordination of the transmission ratio between the wheel, connected to the connecting rod, and the shaft wheel, the oscillatory angle of the shaft wheel or the wiper shaft can be determined.

WHAT WE CLAIM IS: 1. A wiper device for the windscreens of motor vehicles, the device comprising a rotatable drive crank, a connecting rod articulated at one end to the drive crank and connected pivotally by its other end to the axis of a rotatable wheel operatively connected to a shaft wheel firmly mounted on a wiper shaft by means which transmit peripheral forces, the rotatable wheel having a greater diameter than the shaft wheel, means being provided for guiding the rotatable wheel about the shaft wheel over a predetermined angle along a path fixed relative to a housing of the device.

2. A wiper device as claimed in claim 1 in which the means transmitting the peripheral forces comprise teeth disposed on the periphery of the rotatable wheel and also teeth of the shaft wheel which cooperate with the peripheral teeth of the rotatable wheel the fixed path being provided by a cam with internal toothing that is curved concentrically to the shaft wheel and whose toothing meshes with the teeth of the rotatable wheel.

3. A wiper device as claimed in claim 2, in which the cam with the internal toothing comprises a toothed rack on a part of the housing.

4. A wiper device as claimed in any preceding claim in which at least one plate is mounted, by way of a first bearing, on the wiper shaft and the shaft wheel, and is provided with a second bearing in which the rotatable wheel is mounted.

5. A wiper device as claimed in claim 4, in which one said plate is mounted on each side of the shaft wheel and of the rotatable wheel connecting rod.

6. A wiper device as claimed in claim 1 in which the means transmitting the peripheral forces comprise drawing means which engage the periphery of the shaft wheel and the periphery of the rotatable wheel, the guide way for the rotatable wheel being formed by a flexible longitudinally extending guide member which is at least partially looped about the wheel and whose free ends are kept fixed relative to the housing.

7. A wiper device as claimed in claim 6, in which the rotatable wheel mounted on the connecting rod and the shaft wheel are kept at a distance from each other by means of a support mounted on the wiper shaft so as to be able to oscillate.

8. A wiper device as claimed in claim 6 or 7, in which the rotatable wheel mounted on the connecting rod has a projection which is concentric to its periphery and is of smaller diameter, the guide member engaging its periphery.

9. A wiper device as claimed in any of claims 6 to 8, in which both ends of the guide member are anchored on the surface of a projection of the housing, which is at least approximately concentric to the wiper shaft.

10. A wiper device as claimed in any of claims 6 to 9, in which the guide member is a toothed belt.

11. A wiper device as claimed in any of claims 6 to 10, in which the drawing means comprise a toothed belt.

12. A wiper device constructed and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figure 1 of the accompanying drawings.

13. A wiper device constructed and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figure 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. are formed in the case of the embodiment in Figure 1 by the teeth of the toothed wheel 15 and the teeth of the pinion 18 and in the case of the embodiment in Figure 2 by drawing means 42. Furthermore in both cases the wheel 15 and 32 respectively, mounted on the connecting rod 14, is guided about the shaft wheel 18 and 36 respectively over a certain angle along a frame-fast path 16 and 40 respectively. By means of appropriate coordination of the transmission ratio between the wheel, connected to the connecting rod, and the shaft wheel, the oscillatory angle of the shaft wheel or the wiper shaft can be determined. WHAT WE CLAIM IS:

1. A wiper device for the windscreens of motor vehicles, the device comprising a rotatable drive crank, a connecting rod articulated at one end to the drive crank and connected pivotally by its other end to the axis of a rotatable wheel operatively connected to a shaft wheel firmly mounted on a wiper shaft by means which transmit peripheral forces, the rotatable wheel having a greater diameter than the shaft wheel, means being provided for guiding the rotatable wheel about the shaft wheel over a predetermined angle along a path fixed relative to a housing of the device.

2. A wiper device as claimed in claim 1 in which the means transmitting the peripheral forces comprise teeth disposed on the periphery of the rotatable wheel and also teeth of the shaft wheel which cooperate with the peripheral teeth of the rotatable wheel the fixed path being provided by a cam with internal toothing that is curved concentrically to the shaft wheel and whose toothing meshes with the teeth of the rotatable wheel.

3. A wiper device as claimed in claim 2, in which the cam with the internal toothing comprises a toothed rack on a part of the housing.

4. A wiper device as claimed in any preceding claim in which at least one plate is mounted, by way of a first bearing, on the wiper shaft and the shaft wheel, and is provided with a second bearing in which the rotatable wheel is mounted.

5. A wiper device as claimed in claim 4, in which one said plate is mounted on each side of the shaft wheel and of the rotatable wheel connecting rod.

6. A wiper device as claimed in claim 1 in which the means transmitting the peripheral forces comprise drawing means which engage the periphery of the shaft wheel and the periphery of the rotatable wheel, the guide way for the rotatable wheel being formed by a flexible longitudinally extending guide member which is at least partially looped about the wheel and whose free ends are kept fixed relative to the housing.

7. A wiper device as claimed in claim 6, in which the rotatable wheel mounted on the connecting rod and the shaft wheel are kept at a distance from each other by means of a support mounted on the wiper shaft so as to be able to oscillate.

8. A wiper device as claimed in claim 6 or 7, in which the rotatable wheel mounted on the connecting rod has a projection which is concentric to its periphery and is of smaller diameter, the guide member engaging its periphery.

9. A wiper device as claimed in any of claims 6 to 8, in which both ends of the guide member are anchored on the surface of a projection of the housing, which is at least approximately concentric to the wiper shaft.

10. A wiper device as claimed in any of claims 6 to 9, in which the guide member is a toothed belt.

11. A wiper device as claimed in any of claims 6 to 10, in which the drawing means comprise a toothed belt.

12. A wiper device constructed and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figure 1 of the accompanying drawings.

13. A wiper device constructed and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figure 2 of the accompanying drawings.