GB2186448A

GB2186448A - Inhibiting starting of a motor vehicle engine by an intoxicated driver

Info

Publication number: GB2186448A
Application number: GB08702490A
Authority: GB
Inventors: Brian Kenneth Crabtree
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-02-05
Filing date: 1987-02-04
Publication date: 1987-08-12
Anticipated expiration: 2007-02-04
Also published as: GB8602806D0; GB8702490D0; GB2186448B; FR2619419B1; FR2619419A1

Abstract

A motor vehicle's ignition circuit 10 comprises a battery 12, a primary switch 14, a key operated switch 16, and an ignition system 18 including a starter motor. The operation of the primary switch 14 is controlled by a breath analyser 20 whereby a sample of breath is passed via an inlet nozzle 22 into a fuel cell 24 generating a voltage the value of which is proportional to the alcohol content of the breath sample. Comparison means 26 compare this value to a pre-determined value. If the generated value is higher than the pre-determined value the primary switch 14 remains off preventing the ignition system 18 from being energised thus inhibiting starting of the motor vehicle. If the generated value is lower, the primary switch 14 is closed and the vehicle's engine may be started. The breath analyser 20 may include a heater to ensure operation at a substantially constant temperature. The analyser 20 and switch 14 may be encapsulated in resin to prevent tampering. A test based on a change of colour of a solution of potassium dichromate and sulphuric acid may alternatively be used. <IMAGE>

Description

SPECIFICATION A motor vehicle's ignition circuit This invention relates to a motor vehicle's ignition circuit.

Commonly a motorvehicleignitioncircuitisarran- gedsothatinsertionandturning of a key-operated switch completes the ignition circuit. The operation of the key-operated switch allows currentfrom a batteryto energise and operate a starter motor and hence start the motor vehicle's engine.

It is known that motor vehicle drivers are adversely affected by alcohol. The adverse effects include an increase in reaction time and lack of care concerning, and attention to, other road users. Thus a motorvehicle's driver who has consumed alcohol is considered to be a hazard to himself and other road users.

Legislation has been introduced to combat these problems, and this provides for penalties against intoxicated people driving vehicles, a legal limit being defined on the basis of the alcohol content in a per son's blood stream. This alcohol content can be deduced from a sample ofthat person's breath. Such legislation, may act as a deterrent to driving whilst intoxicated but does not go any way towards preventing such an occurrence.

An object of the present invention is to provide an ignition circuit arrangement effective to preventthe starting ofthe engine of a motorvehicle by a person who has a blood alcohol content higherthan a predetermined (e.g. legal) limit,thuspreventingthevehiclefrom being driven.

Pursuant hereto, the present invention provides a motorvehicle'signition circuitincluding akeyoper- ated switch and a starter motor, operation of the key operated switch causing the starter motor to be supplied with electricity, the starter motor then operating to start the motorvehicle's engine, characterised in that disposed in the circuit is a switching arrangement including a primary switch and breath analysis means disposed such that the primary switch will prevent the starter motor from operating until an analysis breath sample suppliedtothe breath analysis means indicates a blood alcohol content below a predetermined limit.

Advantageously the primary switch will, when the motorvehicle'sengine isturned off, require afurther analysis of the driver's breath before restarting of the engine is possible.

Preferably the breath analysis means is supplied with a breath sample via a disposable tube, preferably of plastic, connectable to the analysis means.

Advantageously the breath analysis means is provided with a heating ci rcuit to ensure that the analy- sis of the breath sample is done ata substantially constant temperature.

Preferably the breath analysis means and the primary switch are protected againsttampering by encapsulation in resin thus effectively sealing the analysis means against disturbance ortampering.

Advantageously the breath analysis means includes a fuel cell which is supplied with a quantity of breath, causing the fuel cell to generate a small voltage directly proportional to the alcohol concentration of the breath sample, the breath analysis means further including comparison means to compare this generated voltage with a pre-determined value.

Preferably the breath analysis means includes sampling means to ensure that the breath sample supplied to the analysis means is a deep lung breath sample, that is contains airwhich has been in close contactwith a subject's blood and whose alcohol contact is therefore closest to that in a subject's blood stream.

The invention will be described further, byway of example, with reference to the accompany drawings in which: Figure lisasimplifieddiagrammaticviewofa motor vehicle's ignition circuit according to the invention; and Figure2 is a perspective view of breath analysis means ofthe invention.

The preferred embodiment of a motorvehicle's ignition circuit referred to generally by the reference numeral 10 conforming to the invention includes a battery 12 connected to a primary switch 14. The primary switch 14 is further connected via a key operated switch 16 to a motor vehicle's ignition system 18 including a starter motor.The circuit 10 is so connected that, when the primary switch 14 is in its on condition, operation of the key-operated switch 16 causes the starter motor in the ignition system 18to be energised and hence to startthe engine of a motor vehicle (not shown). The condition of the primary switch 14 is controlled by breath analysis means 20 which are provided with an inlet nozzle 22. A breath sample of sufficient volume provided by the motor vehicle's user (not shown) blowing or exhaling into the inlet nozzle 22 is passed to a fuel cell 24 of known design.The alcohol present in the breath sample causes the fuel cell 24to produce a small electric currentwhose voltage is directly proportioned to the alcohol content of the breath sample. The current thus produced by the fuel cell 24 is supplied to comparison means 26 where it is compared to a predetermined value. This pre-determined value can be pre-setto relate to any desired blood alcohol content For example, the value may be equal to the legal limit defined by the lawfor blood alcohol level.The comparison means 26 are connected to the primary switch 14 and the results of the comparison between the generated value and the pre-determined value will cause the primary switch 14to be in its on or its offcondition.If the generated value is higher than the pre-determinedvaluethe primary switch 14remains in its off position. if the generated value is lower than the pre-determined value then the primary switch 14 is in its on condition allowing the ignition system 18to be energised.

Referring now to Figure 2, which illustrates a preferred practical embodiment of the breath analysis means 20 according to the invention, an outer casing 28 has an electrical port 30 allowing the analysis means 20 to be connected to a motorvehicle's igni- tion circuit (not shown) and a removable access plate 32 allowing authorised access to the breath analysis means 20. The casing 28 has on its frontface 34two push operated buttons 36,38 marked SET and READ respectively, four indicator lights 40,42,44,46 marked BLOW, READ, PASS and FAIL respectively, an on-off switch 48 controlling a heating circuit (not shown) and a port 50 adapted to allow the connec tionofa plastictube(notshown).

In orderforan operatorto start the engine of a motorvehicle provided with an ignition circuitac- cording to the invention the operator must first ac- tivate the key operated switch 16 and then depress the SET button 36 on the casing's face 34. The BLOW light 40 is illuminated and the operator connects a disposable tube (not shown) to the port 50. The operatorthen exhales into the tube for a period often seconds. Any interruption of the exhalation during this period will result in the termination of the sequence and the re-setting of all controls thus requiring the operator to commence the procedure again from the beginning. During the final two seconds ofthe exhalaction the READ light42 is illuminated requiring the operatorto depress the READ push button 38.Failure to do so will result in the re-setting of the analysis means 20 requiring a new sequence to becommen- ced. The depression of the READ button 38 causes a sample of the breath to be passed to the fuel cell 24 (see Figure 1 ) causing the generation of an electric currentwhich is passed to the comparison means 26.

The value generated is compared to a predetermined value to determine if the primary switch 14 is to be energised. If the blood alcohol level as measured by the fuel cell 24 is below the predetermined value the primary switch 14will close allowing the ignition system 18to be energised and illuminating the PASS light44. If the ievel measured is higher than the pre-determined value the primary switch 14will remain offimmobilising the ignition system 18 and illuminating the FAIL light 46. Turning off the key operated switch 1 will reset the analysis means enabling afurthersampleto be provided.

As the fuel cell 24 can operate accurately under only a limited variation of environmental conditions, for example, temperature, a heating circuit is provided operated manually by a heating switch 48.

Adjustment and calibration ofthe analysis means is possible via the access plate 32 which is sealed to preventunauthorised adjustmentofthe predetermined value stored in the comparison means 26.

The foregoing is illustrative of the preferred emb odiment ofthe invention and variations may be made thereto. The measurement of the blood alcohol level can be accomplished by different means than that previously described,for example, a test based on the change of colour of a solution of potassium dichromate and sulphuric acid could be used. The casing need not be as described or have the controls specified thereon. Other variations may also be possible.

Claims

1. A motorvehicle's ignition circuit including a key operated switch and astartermotor, operation of the key operated switch causing the starter motor to be supplied with electricity, the starter motor then operating to start the motor vehicle's engine, characterised in that disposed in the circuit is a switching arrangement including a primary switch and breath analysis means disposed such that the primary switch will prevent the starter motor from operating until an analysis of a breath sample supplied to the breath analysis means indicates a blood alcohol content below a pre-determined limit.

2. A motor vehicle's ignition circuit as claimed in claim 1 wherein the primary switch will, when the motor vehicle's engine is turned off, require a further analysis ofthe driver's breath before restarting of the engine is possible.

3. An ignition circuit as claimed in claims 1 or2 wherein the breath analysis means is supplied with a breath sample via a disposabletube connectableto the analysis means.

4. An ignition circuit as claimed in claims 1,2 or3 wherein the breath analysis means is provided with a heating circuit to ensure that the analysis ofthe breath sample is done ata substantially constant temperature.

5. An ignition circuit as claimed in any preceding claim wherein the breath analysis means and the primary switch are protected againsttampering by encapsulation in resin thus effectively sealing the analysis means against disturbance or tampering.

6. An ignition circuit as claimed in any preceding claims wherein the breath analysis means includes a fuel cell which is supplied with a quantity of breath causing the fuel cell to generate a small voltage directly proportional to the alcohol concentration ofthe breath sample, the breath analysis means further including comparison means operating to compare the generated voltage with a pre-determined value.

7. An ignition circuit as claimed in any preceding claim wherein the breath analysis means includes sampling means to ensure that the breath sample supplied to the analysis means is a deep lung breath sample.

8. A motor vehicle's ignition circuit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.