Communications: electrical – Land vehicle alarms or indicators – External signal light system
Patent
1995-10-02
1997-05-20
Hofsass, Jeffery
Communications: electrical
Land vehicle alarms or indicators
External signal light system
340438, 340439, 340458, 361 49, 361 88, B60Q 144
Patent
active
056316267
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a circuit for triggering the warning lamp of an automotive vehicle brake system with electronic anti-lock and/or traction slip control, including a power driver through which the warning lamp current flows in the presence of a monitoring signal or error signal initiated by malfunction of the controller.
In brake systems with electronic anti-lock or traction slip control, disconnection of the control when malfunction occurs is common practice or is even provided by the law to ensure at least braking operations without control in the case of malfunction. The detection of a fault is optically signalled by way of a warning lamp. Known brake systems of this type include a mechanic relay, for example a so-called master relay, having a normally open contact by which the controller of the brake system can be switched on and off. This relay has also a normally closed contact by which the warning lamp is switched on when the relay is deenergized.
When instead of the mechanic relay a semiconductor relay is used (which is favorable for various reasons), the problem is that, if the current supply fails, there is no possibility of triggering the warning lamp which is comparable with the normally closed contact of the mechanic relay. However, flashing up of the warning lamp whenever the control is disconnected is an important safety aspect and often even a legal provision. Therefore, an object of the present invention is to ensure switching on of the warning lamp in a simple way and without considerably increasing the manufacturing expenditure, even if the controller is energized by a semiconductor relay.
It has been found that this object can be achieved by the improvement of a circuit for triggering warning lamps as described in the accompanying claim 1. Favorable embodiments of the circuit according to the present invention are described in the subclaims.
Thus, according to the present invention, the triggering circuit of the warning lamp is supplemented by an additional circuit which, when supply voltages are available, does not take effect on the triggering of the warning lamp and which becomes self-conductive and, therefore, closes the current path leading via the warning lamp to ground in the event of failure of any or all of the supply voltages.
The additional circuit substantially comprises a small number of low-power transistors which can be provided by modifying the integrated warning lamp driver circuit. The additional manufacturing expenditure required is minimized.
Further features, advantages and possible applications of the present invention can be seen in the following description of details of the present invention by way of the accompanying drawings.
In a schematically simplified view in the drawings,
FIG. 1 is a circuit for triggering warning lamps, the various connections being shown symbolically, and
FIG. 2 is an enlarged view of details of the actual warning lamp triggering circuit according to FIG. 1.
FIG. 1 shows a module 1 representing the circuit for triggering warning lamps according to the present invention. This circuit is an integrated circuit comprising, among others, a power transistor or power driver 2 by way of which the current for flashing up of the warning lamp 3 is conducted when a monitoring signal or a signal indicating a fault exists. For example, a power field effect transistor FET can be used as power driver 2. The monitoring signal or signal to trigger the transistor 2 is supplied to the circuit 1 via the warning lamp inlet WL-IN.
The warning lamp circuit 1 in the embodiment of FIG. 1 is supplied with two voltages of a different magnitude. In the present example, a voltage of 5 volt stabilized by a voltage controller is applied to inlet VCC5, while the vehicle battery voltage of 12 volt, for example, is applied directly to second supply inlet VCC12 in this case. The battery voltage is supplied by an ignition contact terminal IGN. The warning lamp 3 is connected by a terminal WL-OUT. Also, the warning lamp is energized by the ignition switch IGN
REFERENCES:
patent: 4016457 (1977-04-01), Frait
patent: 4709223 (1987-11-01), Crapanzano
patent: 5129259 (1992-07-01), View et al.
English Translation of the Int'l Preliminary Examination Report for Appln No. PCT/EP94/00771.
Search Report of the German Patent Office for Application P4310530.0.
Application Note Publications Elektronik 11/27.5.1988.
Engelmann Mario
Fey Wolfgang
Zydek Michael
Hofsass Jeffery
ITT Automotive Europe GmbH
Lewis J. Gordon
Pope Daryl C.
Twomey Thomas N.
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