GB2342284A

GB2342284A - Windscreen wiper mechanism

Info

Publication number: GB2342284A
Application number: GB9922739A
Authority: GB
Inventors: Reuben Agnon; Rolf Zumbuelte; Michael May
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-10-05
Filing date: 1999-09-24
Publication date: 2000-04-12
Anticipated expiration: 2019-09-24
Also published as: GB2342284B; GB9922739D0; ES2158806B1; ES2158806A1; FR2784068A1; FR2784068B1; DE19845674A1

Abstract

A windscreen wiper mechanism (10) comprises at least one wiper (14), which is driven by a motor (18) to be movable between two reversal positions (21), and a control unit (20) connected with the motor (18). A sensor (22) detecting acceleration is mounted at the wiper (14) and connected with the control unit (20). The signals of the sensor can be used by the control unit to regulate the movement of the wiper.

Description

2342284 1 WINDSCREEN WIPER MECHANISM The present invention relates to a

windscreen wiper mechanism and to methods for operating and for optimising operation of such a mechanism.

In known windscreen wiper mechanisms, one or more wipers are driven by a motor directly or by way of a linkage and move in reciprocating manner across the pane to be wiped. For optimisation of such a windscreen wiper mechanism, various environmental influences and system parameters are to be observed, as for example striation formation in dependence on the quantity of rain and noise output during the wiping operation and in the end positions, so that a compromise, can be achieved for optimisation of operation.

According to a first aspect of the invention there is provided a windscreen wiper mechanism with at least one wiper, which is driven by a motor and movable with a pendulating movement between two reversal positions, and with a control unit connected with the motor, characterised in that a sensor detecting the acceleration is mounted at the wiper and connected with the control unit.

Preferably, the control unit regulates the rotational speed of the motor in dependence on the signal delivered by the sensor. A target movement profile for the pendulating movement can be filed in a storage device in the control unit and the control unit can act on the motor in corrective manner in dependence on the values transmitted by the sensor when the values deviate from the values of the target movement profile stored in the storage device.

A wiper mechanism embodying the invention may have the advantage that the dynamic behaviour of the wiper can be detected and corrected in every position. Consequently, a greatest possible wiping speed in the field of view of the driver on the one hand and a control or regulated movement towards reversal positions or a parking position on the other hand can be achieved. In this mechanism there is recognition that not only the speed of the wiper across the pane, but also its acceleration, have appreciable influence on the mentioned parameters.

In the case of a motor controlled or regulated directly by the signal delivered by the sensor, environmental influences, such as a dry, moist or wet pane or a loading of snow can be 2 reacted to directly. The speed can be kept high in the regions of view and can be braked in targeted manner on reaching the reversal positions. It is thereby achieved that, in spite of the rapid wiping across the region of view, a tuming-over of the wiper at the reversal positions does not occur even in the case of low values of friction. The tilting-over noise in the reversal positions is kept small due to reduction in the speed or acceleration.

If a target movement profile for the wiper movement is picked up by means of the sensor and filed in a store in the control unit, a rapid access to the optimum movement course is possible, which is compared with the actual movement course. The control unit can then react directly to deviations.

According to a second aspect of the invention there is provided a method for operating a windscreen wiper mechanism with at least one wiper, which is driven by a motor and movable with a pendulating movement between two reversal positions, and with a control unit connected with the motor, characterised in that an acceleration sensor is mounted at the wiper, that the signals of the acceleration sensor are fed to a control unit and that the signals are used directly or prepared as regulating magnitude for the movement of the windscreen wiper.

According to a third aspect of the invention, there is provided a method for optimising a movement profile of a windscreen wiper mechanism with at least one wiper, which is driven by a motor and movable with a pendulating movement between two reversal positions, and with a control unit connected with the motor, characterised in that a sensor detecting the acceleration is mounted at the wiper, that the course of the movement is picked up for different target movement profiles by the sensor and fed to the control unit, that parameters such as noises, striations or tilting behaviour of the wiper lip are detected and that at least one target movement profile, which is optimised for at least one parameter and according to which the motor is operable, is filed in the control unit.

In the case of the method for operating the wiper mechanism, the signals of the sensor can be used by the control unit as regulating magnitudes for the movement of the wiper, deviations from the optimum course of movement being registered directly and corrected in the shortest time. In this manner, the actual movement course is largely approximated to the optimum movement course. In the case of the method for optimisation of the movement profile, it is possible to undertake a presetting for desired windscreen wiper 3 mechanisms, according to which the windscreen wiper mechanisms employed in the series operate almost optimally. It is possible to control the thus optimised windscreen wiper mechanism even without a sensor detecting the acceleration, in which case the environmental influences influencing the movement course cannot, of course, be detected directly. For that reason, the mechanism, even when optimised in such a manner, is preferably operated with a sensor detecting the acceleration.

Embodiments of the wiper mechanism and examples of the method of the invention will now be more particularly described with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram of a windscreen wiper mechanism embodying the invention; and Fig. 2 is a diagram showing angular speed of a wiper of the mechanism entered as a function of the movement angle.

Referring now to the drawings, there is shown in Fig. la windscreen wiper mechanism 10 for a windscreen pane 12 of a motor vehicle, in which two wipers 14 are driven by a motor 18 via a linkage 16. The motor 18 is influenced by a control unit 20. In operation, the wipers 14 oscillate between two reversal positions 21 and 23 through an angle cc. The lower reversal position 23 in this case also defines the parking position. The parking position can also assume a different position, but preferably is a lower position.

The wipers 14 are illustrated schematically and usually consist of a wiper arm and a wiper blade articulated thereto.

A sensor 22, which detects the wiper acceleration and which is connected by way of a signal line 24 with the control unit 20, is mounted on the wiper 14. The position of the sensor 22 at the wiper 14 depends inter alia on the sensitivity of the sensor 22. The greatest possible speed, and therefore the greatest possible acceleration, to be detected fie in the region of the wiper tip. Mounting in this region would, however, be perceived to be disturbing to vision and is unfavourable for the disposition of the signal line 24, in particular in the case of a change of wiper blade. It is therefore desired to mount the sensor 22 as closely as possible to the pivot point of the wiper 14.

4 In Figure 1, a sensor 22 is shown at only one wiper 14. However, it is feasible to mount such a sensor at each wiper 14 and to connect it with the control unit 20. The received signals can then be averaged or compared in the control unit so that the failure of one wiper 14 or one sensor 22 could be recognised. In the case of a wiper mechanism with a separate motor for each wiper, each wiper could then be equipped with a sensor connected with an individual control unit of the respective motor.

In operation, the wipers 14 reciprocate according to the angle a between the two positions 21 and 23 and in that case are accelerated and decelerated at least in the regions of the reversal positions. The acceleration and deceleration (retardation) values are detected by the sensor 22 and delivered to the control unit 20, which in its turn regulates the motor 18 according to the signals. Regulation processes of that kind, which, for example, influence current feed to the motor and thereby its rotational speed, are known and thus are not further described.

It is also possible that the control unit 20 controls the motor 18 in known manner and the signal received by the sensor 22 is used merely for monitoring of the movement.

The control unit 20 comprises a storage device 26 in which at least one empirically ascertained target movement profile for the wiper movement is filed. The signals received by the sensor 22 are compared in the control unit 20 with the filed values of the target movement profile directly or after preparation thereof and a regulating magnitude is derived, by which the operation of the motor 18 is influenced.

In operation of the wiper mechanism 10, the values transmitted by the sensor 22 to the control unit 20 are consequently used to derive a regulating magnitude for the movement of the wiper 14.

Target movement profiles 28, 30 and 32 in the form of a movement angle speed entered as a function of the movement angle are illustrated in a diagram in Fig. 2. The movement profiles in that case correspond with the signals delivered and prepared by the sensor 22. The different profiles 28, 30 and 32 are achieved either by the drive control of the motor 20 being varied or by different environmental conditions, such as dry, moist or wet pane, being simulated. In this manner, a target acceleration profile can be selected, which represents an optimum compromise between the individual parameters representing wiping quality, noise development or the like. It is, however, feasible to file several movement profiles 28, 30 and 32 in the storage device 26 and to change to the appropriate target movement profile 28, 30 and 32 according to the weather.

6

Claims

1. A windscreen wiper mechanism comprising a wiper, a motor operable to drive the wiper for reciprocating movement between two positions of reversal, detecting means arranged at the wiper to detect rate of change in the speed of movement thereof and control means responsive to values indicative of the detected rate to influence or monitor operation of the wiper.

2. A mechanism as claimed in claim 1, the control means being arranged to regulate the rotational speed of the motor in dependence on said values.

3. A mechanism as claimed in claim 1 or claim 2, the control means being arranged to store a target movement profile for the reciprocating movement of the wiper.

4. A mechanism as claimed in claim 3, the control means being arranged to influence the motor operation in a corrective manner in dependence on the difference between said values and values of the stored movement profile.

5. A windscreen wiper mechanism substantially as hereinbefore described with reference to the accompanying drawings.

6. A method of operating a windscreen wiper mechanism with a wiper driven by a motor for reciprocating movement between two positions of reversal, the method comprising the steps of detecting rate of change in the speed of movement of the wiper by detecting means arranged at the wiper and applying signals indicative of the detected rate to control means for regulating operation of the motor in dependence on the detected acceleration.

7. A method as claimed in claim 6, wherein the step of influencing comprises regulating the rotational speed of the motor in dependence on said signals.

8. A method of optimising the profile of movement of a windscreen wiper driven by a motor for reciprocating movement between two reversal positions, the method comprising the steps of detecting the acceleration of wiper by detecting means arranged at the wiper, wherein the course of the movement is picked up for different target movement profiles by 7 the detecting means and fed to a control unit connected with the motor, detecting noise, stdations, tilting behaviour of the wiper lip and/or another aspect or aspects of the wiper operation and/or state, and storiing at least one target movement profile, which is optimised for at least one parameter and according to which the motor is operable, in the control unit.