Wiper circuit system for motor vehicles

Details Wiper circuit system for motor vehicles Wiper circuit system for motor vehicles

1988-08-18

1989-12-05

Ro, Bentsu

Electricity: motive power systems

Periodic, repetitious or successive operations control of...

Variable periods or intervals between controlling operations

318DIG2, B60S 108

Patent

active

048855120

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to wiper systems of modern motor vehicles in which different modes of operation can be chosen via an operating switch, as for instance continuous operation, intermittent operation, wipe-wash-operation. For implementing these different modes of operation a control device with a circuit is needed, which circuit releases time-dependent switching and/or controlling signals. A time-dependent switching signal, for example, determines the interval of the intermittent operation, another time-dependent switching signal could determine the wipe-after-wash period during the wipe-wash operation. In general, the time taken by such a switching signal is to be as constant as possible and does not depend on any conditions of environment.
Wiper systems, in which the wiper motor is switched off, if the wiper should be blocked outside its parking position and thus does not reach its parking position within a predetermined period of time, are known. In order to implement this anti-blocking protection, time-dependent controlling signals are needed, which are generated in the circuit. As known from experience, it is problematic to determine the period of time needed for controlling signals in this application because the period of time of a wiping cycle depends on influences of environment. Experiments made with wiper system, in which all time-dependent switching and controlling signals were derived from a timing signal with highly constant frequency have not always satisfactorily been successful.
Thus the object of the present invention is to provide a wiper system by using easiest means, which wiper system works in an optimal and safe manner during all modes of operation.


SUMMARY OF THE INVENTION

Thereby the invention is based on the idea that certain switching and controlling signals should be derived from a highly constant timing signal because, as far as the accuracy of the time taken by these signals is concerned, special requirements are made. The time taken by other switching and controlling signals, however, should be variable and depend, for instance, on the voltage. Thus, according to the present invention a timing signal with constant frequency or a timing signal with variable frequency within a certain area is produced as a function of the chosen mode of operation. From these timing signals time-dependent switching and controlling signals are derived. The change from constant to variable timing frequency could also depend on the operating state of the electric motor or on the control or switching state of the switching element via which the electric motor is controlled.
The basic idea of the present invention can be carried out in different ways. For instance, two timing oscillators could be assigned to the circuit, which is normally made in an integrated technique, the one timing oscillator of which releases a timing signal with constant frequency and the other timing oscillator of which releases a timing signal with variable frequency. In dependence of the chosen mode of operation, the timing signal of the one or the other oscillator could then be developed. Such a circuit, however, is not easily made because two oscillators with the time-determining components are needed. Thereby it is of a disadvantage that apart from requiring more space, two time-determining devices are necessary on the chip of the integrated circuit, which device cannot readily be integrated and which therefore have to be soldered on a printed circuit board as additional components.
Therefore an alternative is preferred in which only one oscillator is integrated into the circuit, the timing frequency of which can be varied by an input valve. In the easiest case this is a so-called oscillator controlled by voltage, to which oscillator a constant voltage is conducted in the one case, and to which a variable voltage depending on the battery voltage of the motor vehicle is conducted in the other case. As to such a solution only little space is needed on the chip for generating the changeable

REFERENCES:
patent: 4314186 (1982-02-01), Gille et al.
patent: 4320329 (1982-03-01), Gille et al.
patent: 4388574 (1983-06-01), Bois et al.
patent: 4567412 (1986-01-01), Graham
patent: 4620141 (1986-10-01), McCumber et al.
patent: 4689535 (1987-08-01), Tsunoda et al.

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