Circuit configuration for monitoring a plurality of coils

Details Circuit configuration for monitoring a plurality of coils Circuit configuration for monitoring a plurality of coils

1995-06-15

1997-06-10

Fleming, Fritz

Electricity: electrical systems and devices

Control circuits for electromagnetic devices

For relays or solenoids

H01H 4700

Patent

active

056382472

DESCRIPTION:

BRIEF SUMMARY
This application is the U.S. national-phase application of PCT International Application No. PCT/EP93/03414.


BACKGROUND OF THE INVENTION

The present invention relates to a circuit configuration for monitoring a plurality of coils and the final stages for actuating these coils, for example, the valve coils of a brake system with anti-lock or traction slip control. The coils are connected to the supply voltage by way of a joint supply line and a joint relay. The final stages are driven by test pulses according to a predetermined program and the potential change at the individual coil actuating connections is detected. The coils are monitored by this circuit for operability, shunts, line interruptions and other defects.
DE 39 25 418 A1 discloses a circuit configuration of this type. Short test pulses are applied to final stages, which serve to control electrically operable valves, according to a predetermined pattern, and the reaction to the test pulses is monitored. To this end, the actuating connections of the individual valves are joined by way of a comparator circuit and, in addition, an OR-linking. The comparator circuit includes a row of non-equivalence or equivalence elements. The output signals of the comparator circuit and the OR-linking are supplied to another comparator element, the output signal of which is finally assessed in response to the test pulses for monitoring the final stages.


SUMMARY OF THE INVENTION

An object of the present invention is to provide a monitoring circuit of this type which permits detection of most various errors, such as short circuits, shunts, line interruptions, as well as errors of the monitoring components themselves, with great reliability. Incurring as little expenditure as possible for this monitoring operation is desired.
It has been found that this object may be achieved by a circuit configuration of the previously mentioned type, the characteristic features of which are that the supply line is connected to a first potential monitor and, by way of a high-ohmic resistor, is connected to a test voltage source, wherein the potential prevailing on the supply line can be determined by the first potential monitor after the voltage supply has been interrupted or the relay contact has been opened.
Whether leakage currents occur and, under certain circumstances, whether the leakage currents are within or outside a tolerable range may be recognized by connecting the supply line to a test voltage source and inserting a high-ohmic resistor, interrupting the voltage supply during the testing operation by means of the relay, and measuring the potential which prevails on the supply line during this test period. Depending on the magnitude of such a leakage current, different reactions of the monitoring circuit, namely instantaneous deactivation of the control, decelerated deactivation or maintaining of the control, are expedient. Of course, short circuits between the supply line or the coil and the ground, defective final stages, failing actuation and other errors may be detected as well.
According to a favorable aspect of the present invention, a second potential monitor is connected to the supply line and, upon activation of the supply voltage, monitors the proper potential change on the supply line which is caused by operation of the relay.
Expediently, the voltage monitors are connected to the supply line by way of voltage dividers to determine voltage tolerance ranges which are still admissible for proper operation.
The use of a semiconductor relay for activating and deactivating the voltage supply for the coils is particularly advantageous because such semiconductor relays react very quickly to actuating signals. This renders it possible to perform the test program at different points of time, even during the normal operation, without impairing the proper operation of the anti-lock or traction slip control.
Expediently, an analog/digital converter is used as a first potential monitor so as to determine and assess the magnitude of potential displacements due to certa

REFERENCES:
patent: 3841712 (1974-10-01), Syria
patent: 4340935 (1982-07-01), Anlauf et al.
patent: 4764884 (1988-08-01), Noyori
patent: 5099198 (1992-03-01), Bleckmann et al.
patent: 5193887 (1993-03-01), Bleckmann et al.

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