GB2282718A

GB2282718A - A direction indicator and hazard warning system for a motor vehicle

Info

Publication number: GB2282718A
Application number: GB9419352A
Authority: GB
Inventors: Martin Krug; Tobias Reis; Uwe Manzke; Jurgen Kiehne; Horst Dahm
Original assignee: Daimler Benz AG; Mercedes Benz AG
Current assignee: Daimler Benz AG
Priority date: 1993-10-08
Filing date: 1994-09-26
Publication date: 1995-04-12
Anticipated expiration: 2014-09-26
Also published as: ITRM940632A1; DE4334371C1; GB9419352D0; FR2710886B1; ITRM940632A0; GB2282718B; FR2710886A1; IT1274942B

Abstract

The invention relates to a direction indicator and hazard flashing light system for motor vehicles, consisting of a load-controlled flasher unit, a hazard warning switch and a direction indicator switch. According to the invention, a separate load-controlled flasher current path with a separate current demand is provided for hazard warning and for direction indication, the paths being separatedly but synchronously switched by a flasher relay which is constructed as a double contact relay. <??>The separate current demand permits activation of the direction indicator switch to be distinguished from activation of the hazard warning switch and also their simultaneous activation to be detected unambiguously. This possibility is utilised in a development in such a way that when the two flasher switches are activated simultaneously the flasher relay is not activated and thus opened while a flasher current is fed into the direction indicator path by an auxiliary clock transmitter. <??>The flasher system according to the invention reduces the outlay on cabling and load switching relays in comparison with known flasher systems with a comparable range of functions.

Description

1 2282718 A direction indicator and hazard warning system for a motor

vehicle The invention relates to a direction indicator and hazard warning system for a motor vehicle, comprising a flashing transmitter for emitting an intermittent flasher signal, a hazard warning switch for passing on the flasher signal to flasher lamps on both vehicle sides, and a direction indicator switch for passing on a flasher signal selectively to the flasher lamps of the right-hand or left-hand vehicle side.

A f lasher system of this type is used in many vehicles and is disclosed, for example, in DE 41 23 270 C1 in conjunction with a break-in/theft warning system. This f lasher system uses a load-controlled control circuit with a single flasher relay. The method of operation of a loadcontrolled control circuit is characterized as follows: the f lasher relay switch is open in the quiescent state so that, when a f lasher switch (direction indicator or hazard warning switch) is operated, initially only a small current f lows to the f lasher lamps via a highvalue resistor which is connected in parallel with the switching link of the f lasher relay. This measurement current then initiates the pulsed driving of the f lasher relay, whose switching link shortcircuits the high-value measurement resistor and connects the flasher lamps intermittently to the positive potential. Such a load-controlled flasher system has the advantage that the serviceability of the external circuitry can easily be checked, since the f lasher lamp current is passed through the flasher switches and a defect in the circuit is detected by interrogating the current and/or voltage on the measurement resistor.

In the case of these conventional systems, hazard warning operation is selected, in a known manner, in that all the f lasher lamps on both sides of the vehicle are connected via the hazard flasher switch, and they are jointly connected to the clock transmitter. This has the disadvantage that, in 1 2 hazard warning operation, a change of lane cannot be indicated since the right-hand f lasher lamp group and the left-hand flasher lamp group are electrically shortcircuited and can no longer be driven individually. A further disadvantage is that, in order to enable hazard warning operation even when the ignition is switched of f, that is to say when the ignition switch is open, the hazard warning switch requires a second switching level with a changeover switch and three further connections. In consequence, on operation of the hazard warning switch, the supply connection of the clock transmitter is switched over from positive (terminal 15 in the DIN nomenclature) to continuous positive (terminal 30), as a result of which the clock transmitter is supplied directly f rom the vehicle battery, bypassing the ignition switch.

Furthermore, various documents disclose hazard warning systems of different types, which have none of the disadvantages mentioned above in this context, but have other disadvantages. DE 40 30 513 Al may be quoted as an example of this, in the case of which the left-hand and right-hand flasher lamps are in each case switched intermittently by means of a dedicated load switching relay, the load switching relays being driven by a control circuit. The operating mode of the control circuit can be predetermined by the position of a hazard warning and direction indicator switch which is of simple construction and must be connected to the control circuit independently of the flasher lamps. In addition to the increased cabling cost, it is disadvantageous that a dedicated costdriving output stage with a load switching relay is required for each flasher lamp group, so that, in comparison with a flasher lamp system of the known type, a considerable cost disadvantage results. In addition, a dedicated control current is passed through the hazard warning and direction indicator switch so that simple checking of the external circuitry - in contrast to the situation in the case of the loadcontrolled flasher systems, where the flasher lamp R 3 current is passed through the f lasher switches - is not directly possible.

DE 41 13 455 Al and DE 41 37 611. Al further disclose load-controlled flasher systems in which, on the basis of a common connection to the continuous positive (terminal 30), the current paths for the hazard flashers and the direction indicators are broken by a load switching relay which is constructed as a double-contact relay and is pulsed synchronously.

The present invention seeks to reduce the cost f or making contact with the hazard warning switch with minor modification to a hazard warning system of this type, of the advantageous, load-controlled type. In addition, it is intended to be possible to upgrade the circuit arrangement using simple means so that a change in driving direction can be indicated even during hazard warning operation.

According to the present invention there is provided a direction indicator and hazard warning system f or motor vehicles, comprising a flashing transmitter for emitting an intermittent f lasher signal, a hazard warning switch f or passing on the f lasher signal to f lasher lamps on both vehicle sides, and a direction indicator switch for passing on a flasher signal selectively to the flasher lamps of the right-hand or left-hand vehicle side, - the direction indicator switch having two stationary contacts which are in each case connected to the f lasher lamps on one vehicle side and having a changeover contact which is connected to a switching contact of a f lasher relay, - the flashing transmitter having a control circuit with an integrated clock generator, and the generator output driving the control connection of the flasher relay with an intermittent control signal when the hazard warning switch or the direction indicator switch has been operated, - the control circuit using current interrogation to detect whether a f lasher switch (direction indicator or hazard warning switch) has been operated, wherein the flasher relay 4 has a double contact, - the first switching link of the flasher relay being connected on one side to the positive terminal, which is connected via the ignition switch of the motor vehicle, of the on-board network, and on the other side to the changeover contact of the direction indicator switch, and - the second switching link of the flasher relay being connected on one side to the unswitched positive pole of the on-board network and on the other side to the changeover contact of the hazard warning switch.

The major essence of the invention comprises the provision of a dedicated load-controlled flasher current path, with in each case one dedicated current interrogation, in each case for hazard flashing and for direction indicator indication, the paths being isolated but switched synchronously by the load switching relay, which is constructed as a double-contact relay. only a single load switching relay is thus required, in a costsaving manner. The second switching level in the hazard warning switch in order to change the supply over from positive to continuous positive can also be omitted since the different supply connection is implemented by means of the separate current paths for hazard flashers and direction indicator indication.

In addition, the separate current interrogation makes it possible to distinguish between operation of the direction indicator switch and operation of the hazard warning switch, and also to identify unambiguously their simultaneous operation. In a development, this capability is used in such a manner that, when the direction indicator switch and hazard warning switch are operated simultaneously, the flasher relay is inactivated and thus opened, while a flasher current is supplied into the direction flashing path by an auxiliary clock transmitter.

An embodiment of the invention will now be described by way of example with reference to the drawing in which:

Figure 1 shows an exemplary embodiment of the flasher i system according to the invention, Figure 2 shows a development of the flasher system according to the invention, which makes driving direction indication possible during hazard warning operation.

The flasher system in Fig. 1 is composed of a flashing transmitter 1 and external components such as a hazard warning switch WBL, direction indicator switch RBL, ignition switch ZO and the two f lasher lamp groups LL, LR. The flashing transmitter 1 in turn contains, on a common board, an electronic control circuit 2 (microcomputer) with connections 2.1-2.5 and circuit elements connected thereto, especially a flasher relay 3 and further contacts for connection of the external components.

A first supply connection 2.1 of the control circuit 2 is connected to the positive potential (continuous positive) KL30, terminal 30 in the DIN nomenclature, of the on-board network. A warning signal connection 2.2 is connected to the changeover contact of a hazard warning switch WBL, which is constructed as a two-gang make contact, whose two stationary contacts are in each case connected to the flasher lamps LL on the left vehicle side and the f lasher lamps LR on the right vehicle side. The second supply connection 2.3 is connected to the positive terminal (positive) KL15, the terminal 15 in the DIN nomenclature, via the ignition switch Zt. A direction signal connection 2.4 is connected to the changeover contact of the direction indicator switch RBL, which is constructed as a two-gang make contact with a neutral centre point and whose two stationary contacts are likewise in each case connected to the left-hand flasher lamp group LL and to the right-hand flasher lamp group LR respectively. Via an output stage which is not illustrated specifically, a generator output 2.5 drives the flasher relay 3 which is constructed as a two-pole power switch. When the flasher relay 3 is activated, the two switching links 3.1, 3.2 are in the closed position, the first switching link 3.1 short-circuiting the first supply 6 connection 2.1 to the hazard signal connection 2.2, and the second switching link 3.2 short-circuiting the second supply connection 2.3 to the direction indicator connection 2.4. Furthermore, both switching links 3.1, 3.2 are bridged by in each case one measurement resistor R1 or R2 respectively, whose resistance is high in comparison with the internal resistance of the flasher lamps LL, LR. The method of operation of the flasher system is as follows:

When the hazard warning switch is operated on its own, the two flasher lamp groups LL, LR are connected to continuous positive KL30 via the measurement resistor R1. In consequence.. a measurement voltage is dropped on R1 which triggers the control circuit 2, via the hazard warning connection 2.2, in such a manner that the flasher relay 3 is driven intermittently via the generator output 2.5. The measurement resistor R1 is bridged synchronously by the switching link 3.1 in a corresponding manner, so that the flasher lamps LL, LR are intermittently connected to the continuous positive KL30 as long as the hazard warning switch WBL is closed and the voltage drop is maintained on the measurement resistor R1. Since the hazard warning current path is supplied from the continuous positive KL30, the hazard warning operation is independent of the position of the ignition switch Zt.

When the direction indicator switch RBL is operated on its own, the selected flasher lamp group LL or LR respectively is connected via the second measurement resistor R2 to the positive terminal KL15, which is connected via the ignition switch ZO. The measurement voltage which is in consequence dropped on the measurement resistor R2 triggers the control circuit 2 via the direction indicator connection 2.4 so that the generator output 2.5 drives the flasher relay intermittently, in a manner which is completely analogous to that during hazard warning operation, as long as the voltage drop is maintained. The measurement resistor R2 is bridged by the switching link 3.2 synchronously in a corresponding manner, so that the i, 7 selected flasher lamp group LL or LR respectively is intermittently connected to the positive KL15. Since the direction indicator current path is connected via the ignition switch ZO to the positive potential, direction indicator operation is possible only when the ignition is switched on.

The switching link 3.1, which is also connected during direction indicator operation on its own, of the hazard warning path has no influence since the hazard warning switch WBL is open and the hazard warning current path is thus interrupted. A corresponding situation applies, of course, for hazard warning operation on its own, in the case of which the switching link 3.2 is also connected, but the direction indicator path is interrupted by the direction indicator switch RBL.

Since, apart from the supply connections KL30, KL15, the flashing transmitter according to the invention requires only two lines which are passed to the outside, namely to the flasher switches WBL, RBL, the cabling cost is reduced in comparison with all the known flasher systems mentioned above. Furthermore, only one, simple changeover switch is required for the hazard warning switch WBL.

Simultaneous operation of the direction indicator and hazard warning switches RBL, WBL can be detected by the control circuit 2 from the voltage drops which occur at the same time on the two measurement resistors R1, R2. Since, however, the two flasher lamp groups LL, LR are shortcircuited via the hazard warning switch WBL, all the flasher lamps are pulsed jointly. However, it is conceivable to provide a dedicated flashing clock during hazard warning operation in order to indicate an intended lane change, so that a following vehicle can be warned, even if there is no information on the direction of the lane change.

A further improvement can be achieved using the development which is illustrated in Fig. 2 and is described in the following text. For this purpose, as a first measure, the flasher system according to the invention is 8 supplemented by decoupling diodes D1, D2 which are in each case inserted into the lines which connect the two stationary contacts of the hazard warning switch WBL to the two flasher lamp groups LL, LR. The diodes D1, D2 are polarized such that the pulsed hazard warning current can supply the flasher lamps LL, LR in the forward direction. on the other hand, the diodes prevent a direction indicator current which is supplied via the direction indicator switch RBL being supplied, if the hazard warning switch WBL is operated at the same time, into the flasher lamp group which is not selected by the operation of the direction indicator switch RBL. As a result of the decoupling, the two line ends which in Fig. 2 are connected to the stationary contacts of the hazard warning switch can be permanently connected and can be jointly connected to a stationary contact, so that a simple make switch could be used as the hazard warning switch WBL.

As a further measure, a second generator output 2.6 is provided, by means of which an intermittent direction indicator current can be supplied via a power output stage 4 into the line to the changeover contact of the direction indicator switch RBL. The control circuit 2 is now designed or programmed such that the flasher relay 3 is inactivated when the hazard warning switch WBL and the direction indicator switch RBL are operated simultaneously. The simultaneous operation of the two flasher switches WBL, RBL is in this case indicated, as described above, by the simultaneous occurrence of a voltage drop on the measurement resistors R1, R2 in the control circuit 2. When the flasher relay 3 is in the quiescent position, its switching links 3.1, 3.2 are open, and in particular there is no flasher current pulsed by the flasher relay 3. Instead of this, this flasher current is supplied from the second generator output 2.6 and the downstream power output stage 4, and is passed via the direction indicator switch RBL to the selected flasher lamp group LL or LR respectively.

If one of the flasher switches RBL, WBL is switched off 1 9 again, this is indicated to the control circuit 2 by the disappearance of the corresponding voltage drop on one of the measurement resistors R1, R2, at which point the control circuit 2 changes again into the flashing mode which is pulsed by the flasher relay 3.

Since direction indication during hazard warning operation is a function which is required comparatively rarely and only temporarily, the output stage 4 can be designed to conform with this less stringent requirement for emergency pulsing. In particular, it is possible to dispense with a further power switching relay. In order to protect the output stage 4 it can furthermore be provided for the emergency pulsing with direction indication to be activated only temporarily and for a change back to hazard warning operation to be made after a predetermined time has elapsed, with pulsing via the flasher relay 3. Seen overall, with the same functional scope, this results in a cost advantage over the flasher systems mentioned above, with in each case one power switching delay for each vehicle side.

Claims

1. A direction indicator and hazard warning system for motor vehicles, comprising a flashing transmitter for emitting an intermittent f lasher signal, a hazard warning switch f or passing on the f lasher signal to f lasher lamps on both vehicle sides, and a direction indicator switch f or passing on a flasher signal selectively to the flasher lamps of the righthand or left-hand vehicle side, - the direction indicator switch having two stationary contacts which are in each case connected to the f lasher lamps on one vehicle side and having a changeover contact which is connected to a switching contact of a f lasher relay, - the flashing transmitter having a control circuit with an integrated clock generator, and the generator output driving the control connection of the flasher relay with an intermittent control signal when the hazard warning switch or the direction indicator switch has been operated, - the control circuit using current interrogation to detect whether a f lasher switch (direction indicator or hazard warning switch) has been operated, wherein the f lasher relay has a double contact, - the first switching link of the flasher relay being connected on one side to the positive terminal, which is connected via the ignition switch of the motor vehicle, of the on-board network, and on the other side to the changeover contact of the direction indicator switch, and - the second switching link of the f lasher relay being connected on one side to the unswitched positive pole of the on-board network and on the other side to the changeover contact of the hazard warning switch.

2. A direction indicator and hazard warning system according to Claim 1, wherein the control circuit has a current interrogation for the hazard flashing circuit which is closed during operation of the hazard warning switch, and a current interrogation, which is independent of this, for the direction indicator circuit, which is closed during operation of the direction indicator switch.

3. A direction indicator and hazard warning system according to Claim 2, wherein the two switching links of the flasher relay are open in the quiescent position and a respective measurement resistor is connected in parallel with each of them, the voltage drop on which measurement resistors is interrogated by the control circuit.

4. A direction indicator and hazard warning system according to Claim 2, wherein, during simultaneous operation of the hazard warning switch and of the direction indicator switch, the clock generator emits an intermittent control signal which differs from that when one of the flasher switches is operated on its own.

5. A direction indicator and hazard warning system according to Claim 2, wherein one decoupling diode is inserted into each of the two lines which connect the hazard warning switch to the left-hand flasher lamp group and to the right-hand flasher lamp group respectively.

6. A direction indicator and hazard warning system according to Claim 5, wherein the flasher relay is inactivated when the two flasher switches are operated simultaneously, so that the two switching links are opened and a power output stage supplies an intermittent flasher current into the line which connects the direction indicator switch to the control circuit.

7. A direction indicator and hazard warning system according to Claim 6, wherein the power output stage is driven on the input side via a second generator output of the control circuit.

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8. A direction indicator and hazard warning system for motor vehicles, substantially as described herein with reference to and as illustrated in the accompanying drawing.

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