GB2135080A - Motor vehicle - Google Patents

Abstract

There is connected with a switch 12 for controlling a rear window heating element in a motor vehicle a timer 14 and a warning device 15 which provides a warning signal to the driver, when the heating element has been energised for a predetermined period. <IMAGE>

Description

SPECIFICATION Motor vehicle According to the present invention, a motor vehicle having an electrically energisable device is provided with a source of electric current, a switch settable in either selected one of an open condition and a closed condition by a user, the switch being adapted to remain in a condition to which it is set without the user maintaining application of a force to the switch, electrically energisable timing means for providing an output signal after the elapse of a predetermined delay from energisation of the timing means and electrically energisable signalling means for providing a warning signal to a driver of a vehicle connected in a circuit such that setting of the switch into the closed condition initiates energisation of said device and of the timing means, and that the signalling means provides the warning signal to the driver when the output signal is provided.

The invention is useful for providing the driver of the vehicle with a warning that the device has been energised for a predetermined period, in order to avoid the driver forgetting that the device is energised. This is particularly useful in a case where the device is an electrically energisable heating element, since the appearance of such an element associated with for example, a screen of a motor vehicle does not change when it is energised.

The invention is also useful for terminating energisation of the device after a predetermined period. Thus, the signalling means may be adapted to warn a driver that the device has been energised for a predetermined period or may be adapted to warn the driver that the device has been de-energised automatically at the end of the predetermined period.

An example of an electric circuit of a motor vehicle embodying the invention will now be described, with reference to the accompanying drawing, which is a diagram of the circuit.

The motor vehicle comprises a source of electric current in the form of a battery 10 and a device 11 which can be energised from the battery. In the particular example illustrated, the device 11 is a heating element for heating a rear screen of the motor vehicle.

The element 11 may be heating element used for some other purpose, for example heating a seat, or some other electrically energisable device, for example a light source.

For controlling energisation of the element 11, there is provided a switch 12 which is readily accessible to a driver of the vehicle. By manipulation of a rocker of the switch, the switch can be set in an open condition or in a closed condition. The switch will remain in either condition to which it has been set, until the rocker is manipulated once more. First electrically energisable signalling means 13 is connected in parallel with the element 11.

The signalling means 13 is a light source which provides a visual signal to the driver whilst the switch 12 is in the closed condition.

There is also connected in parallel with the heating element 11 timing means 14 which, in turn, is connected with a second electrically energisable signalling means 15. The second signalling means 15 also is adapted to provide a warning signal to a driver of the vehicle.

In a case where the second signalling means is a light source, it is positioned where it can readily be seen by the driver and preferably in the vicinity of the switch 12.

Alternatively, the second signalling means may be adapted to provide an audible signal.

In this case, the second signalling means can be situated in various parts of a passenger compartment of the vehicle.

In a case where the heating element 11 is arranged for heating a rear screen of the vehicle, the timing means 14 and second signalling means 15 can be enclosed within a common housing and this housing can be mounted in the vicinity of the rear screen, for example on a rear parcel shelf, in order that electrical connection of the timing means to the element 11 will be a simple operation which can be carried out with disturbance of other parts of the vehicle.

The second signalling means 15 may be a known electronic buzzer. The timing means 14 is adapted to provide an output signal after the elapse of a predetermined delay from energisation of the timing means by closing of the switch 12. The output signal is provided to the second signalling means 15 so that energisation of the latter commences when the predetermined delay has elapsed and continues until the switch 12 is opened.

Energisation of the second timing means 15 is controlled by a transistor T2, the collector and emitter of which are connected in series with the signalling means. Transistor T2 to is set in a conducting condition by an output signal provided, via resistor R3, by a decade counter IC2. For supplying pulses to the decade counter at a predetermined frequency, there is provided a known integrated circuit component IC1. The frequency of the pulses provided by IC1 is dependent upon the values of resistor R1 and capacitor C1. Preferably, resistor R1 is a variable resistor so that the output frequency of ICI can be varied within a limited range.

The electrical power supply for the timer 1C1 and counter 1C2 is fed from the switch 12 through a rectifier 16 which ensures that the power supply to the timer and counter has the required polarity, irrespective of the polarity of the leads 17 and 18 connected between the timing means 14 and the heating element 11.

There is also connected across the rectified power supply a voltage stabiliser comprising transistor T1 and zener diode 19. This voltage regulator maintains the voltage applied to the timer and counter at a level substantially below the output voltage of the battery 10 under all conditions of use, typically at a level in the region of six volts. Accordingly, operation of the timer and counter is not affected by variations in the current drawn from the battery.

Capacitor C2 and resistor R2 provide, on each occasion when the switch 12 is closed, a pulse which re-sets the counter IC2 and thereby establishes transistor T2 in a nonconducting condition. When the switch 12 has remained closed for a predetermined period, the counter provides an output which establishes transistor T2 in a conducting condition. Accordingly, the transistor provides an output signal which energises the second signalling means 15. This signalling means will remain energised until the driver opens the switch 12. If the driver requires energisation of the heating element 11 to be continued, he can immediately re-close switch 12, thereby re-setting counter IC2. The heating element 11, the signalling means 13 and the timing means 14 are all energised substantially simultaneously, upon closing of the switch 12.

Only after elapse of the same delay, will the second signalling means 15 be energised once more.

In a modified circuit (not illustrated) the output signal from timing means 14 may be used to set the switch 12 further switching means connected in series with the switch 12 in an open condition. This will result in deenergisation of the light source 13 and thereby provide a warning signal to the driver that the heating element also has been deenergised.

The following are suitable components for the circuit: R1 470K ohm 0.25W R2 10K ohm 0.25W R3 1K ohm 0.25W R4 860 ohm 0.25W C1 220 MF C2 47 nF T1 and T2 BC107 1C1 555 timer IC2 401 7 decade counter.

Claims (8)

CLAIMS:

1. A motor vehicle comprising a source of electric current, an electrically energisable device, a switch settable in either selected one of an open condition and a closed condition by a user, the switch being adapted to remain in a condition to which it has been set without the user maintaining application of a force to the switch, electrically energisable timing means for providing an output signal after the elapse of a predetermined delay from energi- sation of the timing means and electrically energisable signalling means for providing a warning signal to a driver of the vehicle connected in a circuit such that setting of the switch into the closed condition initiates energisation of said device and of the timing means, and that the signalling means provides the warning signal to the driver when the output signal is provided.

2. A vehicle according to Claim 1 wherein the circuit is so arranged that the signalling means is energised only after said delay.

3. A vehicle according to Claim 1 wherein the circuit is so arranged that the signalling means is energised only after said delay and then remains energised until the switch is set to the open condition.

4. A vehicle according to Claim 1 wherein the timing means is adapted to so control energisation of said device that the device remains energised during said delay and is then de-energised.

5. A vehicle according to Claim 4 wherein the circuit is so arranged that the signalling means is energised during said delay.

6. A vehicle according to any preceding claim wherein said device is an electrical heating element.

7. A motor vehicle having a circuit substantially as herein described with reference to and as shown in the accompanying drawing.

8. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.