GB2092665A - Indicating excessive engine or vehicle speeds - Google Patents

Abstract

Above a preset speed a buzzer and a red light are operated. A counter may indicate the number of times the preset speed is exceeded for more than five seconds. The engine ignition may be switched-off for one minute when the preset speed is exceeded for more than thirty seconds. A green light may be lit when the engine speed is at an appropriate value for the gear engaged, an amber light when the maximum speed for the given gear is approached and the red light when this speed is exceeded. Electrical circuitry is described, Figs. 1 and 2 (not shown). <IMAGE>

Description

SPECIFICATION Aid for vehicle engine usage This invention relates to an aid for vehicle engine usage. Its purpose is to monitor engine conditions of a vehicle during running and provide, by means of a signal, cut out and/or record of conditions, an aid to the driver and/or to a person external of the vehicle (for example at a later date to a Transport Manager), for use in achieving optimum usage of the engine. This aid may facilitate achieving one or more of the advantages of improved fuel economy, minimum wear and tear, longer engine life and safer driving.

Mechanical engine governors have long been known which generally are adapted to automatically cut off fuel supply or ignition if the engine speed exceeds preset limits. Automatic speed control devices are also known which are adapted when actuated, to automatically adjust fuel supply so as to tend to maintain a preset speed. Other devices are known to applicant which are adapted to monitor other characteristics of the engine such as temperature and lubricant pressure and automatically shut-down the engine if these move outside preset safe limits.

An aid for vehicle engine usage in accordance with this invention is adapted to monitor the engine speed during running and primarily to provide warning signals or indications if the engine speed diverges from preset limits and optionally to provide a temporary immobilisation of the engine if suitable corrective action is not taken by a driver after predetermined warnings have been given. The device is also optionally adapted to retain and display for subsequent noting faults which have occurred during running, being faults as defined by a predetermined degree of divergence from preset limits.

Preferably the aid is programmable to any desired maximum engine speed. It is then adapted to automatically set the maximum speed for use in each gear of the vehicle.

Preferably a means for alerting the driver when the limit is approached is a buzzer, activated on infringement of the limit. Preferably also there are red lights which display a warning that the limit is being approached and a green light or lights which display that the engine is at a safe speed.

A fault may, for example, be defined as a period of five seconds in excess of a preset maximum speed and a fault display can be adapted to display the number of five second periods which the engine is run in excess of the maximum speed.

Optionally an engine cut-out can immobilise the engine for a predetermined limit period, for example 1 minute, after more than a certain time in excess of the maximum speed, for example 30 seconds.

Accordingly the device of this invention at least in its preferred embodiments, is intended and adapted not merely to detect and record driver error in the sense of the incurring of faults as defined, but also to condition the driver to drive within set parameters. The device is also adapted as an aid for management in exercising supervisory control for example over fleet vehicles.

The invention will now be more fully described with reference to the accompanying drawings in which the preferred embodiment of the invention is represented, Figure 1 being a circuit diagram for the device, and Figure 3 is a schematic representation of a fascia bearing indicating lights and a counter for the device.

The device in accordance with this preferred embodiment provides various functions which can be described with refefence to the fascia shown in Figure 3. The fascia 1 bears the light 2 which when on indicates that the unit is functioning. The light 3 will only come on if the control cover is removed or the connecting cable is tampered with thereby providing an indication of unauthorised tampering with the device. The light will remain on until a key opperated switch is actuated for 1 5 seconds and then switched on again. The light 4 is on at times that the correct speed in each gear is maintained and can for example be a green light.

The light 5 will come on when the limit of speed for each gear is approached and in this example will come on at 5 miles per hour below the set limit for each gear and can for example be an amber light. The light 6 is the overspeed indicator and this light will come on at one mile per hour above the set maximum speed for each gear while at the same time the correct speed indicator light 4 will go off. At the same time a buzzer is actuated to provide an additional alert to the driven Light 6 can be a red light.

The light 7 is the engine cut-out indicator and this light will come on when the engine is cut and it will remain on for one minute.

The fault counter display 8 is initiated by the overspeed indicator and it will register a point for every 5 seconds that the overspeed is maintained.

The buzzer which is activated when the overspeed indicator comes on so as to give a warning of an overspeed situation goes off when the vehicle returns to the correct speed.

The cut-out unit is used as a last restort to prevent the driver from exceeding the speed limit for more than 30 seconds. When the driver reaches the set speed limit the buzzer sounds. This buzzer must be used as a warning device informing the driver that he has 30 seconds to either change gear or reduce speed. If the driver does not correct the overspeed he knows that the engine will cut out within 30 seconds so that for this period of time he does still have the full facility of the vehicles engine and if he is in the process of overtaking he must either immediately reduce speed and pull back onto the side of the road or accelerate in the present gear so as to complete overtaking and then return to the side of the road.

In this manner overspeeding of the engine of the vehicle is avoided and in general the effect of the buzzer and the warning light 6 will be to train the driver to do this without it being necessary for the cut-out to be actuated.

The basic aim of the device is to advise the driver that he has reached the optimum road and engine speed in each gear. It restricts the maximum road speed by the use of the counter and relay cut-out.

Referring to the circuit diagram shown in Figure 1 the connection of the input terminals numbered 1-4 in this figure on installation of the device is as follows: (1) Plus 12 volts via the ignition switch (2) To negative earth (3) To vehicle's bodywork) ignition coil (to pick up voltage spikes which have a frequency directly related to engine speed, viz. firing of the spark plugs).

(4) Plus 1 2 volts permanent connection.

The device employs a regulated power supply of 1 3 volts which it receives from the car battery.

The voltage varies from 10 volts to 1 5 volts. TR9 is a regulator transistor whose base voltage is controlled by the 13 volt zener diode D14. C8 is used as a smoothing capacitor. The output from TR9 is then fed to the normally on section of the circuit and the contact of RL1. SW1 is the fascia mounted switch which is normally on during use of the device and is used to reset the device if it has been tampered with and the reset light comes on so that the tamper memory is reset and the reset warning light deactivated. Input 2 is a continuous positive voltage from the battery. Input 3 is the switched positive voltage supply and is subject to the ignition switch being switched on.

The power is applied to TR8 which switches on and energises RL1 allowing the RL1 contact to close and therefore powering the main circuits from TR9. On removal of power from terminal 3 C7 begins to discharge at holds TR8 in the on position. The capacitor resistor network of C7, R32 and R33 will hold TR8 on for one minute.

(This will be referred to later.) On application of the positive voltage to terminal 3 C1 charges to its full potential holding the input of gate 11 of IC3 at the logic high state.

This keeps the output of gate 11 at the logic low state therefore preventing TR2 from conducting. The R4, R5 and D1 network causes C1 to discharge to zero volts in 5 seconds taking the gate 11 to the logic low state subsequently producing a high logic state at the output and then allowing the transistor TR2 to switch on. This then provides power to the TR3, TR4 and TR5 group of transistors.

Terminal 4 is connected to the ignition coil of the engine so that the voltage spikes from the ignition coil are then conditioned by the resistor network RS, R1, R2, R3 and R6 and applied to the input of gate 4 of lCl. The gate 4 of IC1 adds an average on these voltage spikes providing that the output is smooth voltage which is dependant on the engine revolutions. This smooth output is then fed to the base of TR 1. TR 1 is then switched on and provides a variable negative potential to R1 1 and to R12. VR1 is used to set the reference voltage for gates 10 and 11. VR 1 is set at the r.p.m. of the engine to allow the desired maximum road speed in top gear.

The resistor network R1 1, R13, R12 and R14 forms two voltage dividers so as to switch the gates 10 and 11 at fractionally different voltages set by the R1.The outputs of gates 10 and 11 are held at the high logic state at all times. This allows TR4 to conduct and D7 is therefore held on. This high logic state is also applied to the base of TR3 and to the base of TR5 which prevents the transistors from conducting. As the voltage drops across the voltage divider, the IC threshold point is reached and gate 11 switches off. TR4 then switches off and allows TR5 to conduct, switching on D6.

When the voltage drops further gate 10 switches off allowing TR3 to conduct switching on D8 and simultaneously placing a high logic state on the input of gate 3 of the IC3 and of gate 4 of the IC4. This also allows the transistor TR7 to conduct switching on the warning buzzer B 1.

Gates 3 and 4 of IC3 form a five second time delay before lC2 is powered. As the input to gate 3 reaches a high logic state the output goes to a low logic state. C4 then discharges holding the input of gate 4 at the high logic state for 5 seconds. When the input goes to the low logic state the output goes to the high logic state allowing TR1 1 to conduct. This in turn switches on IC2. The output pin 3 of IC2 is normally at the high logic state as TRI 1 conducts, whereupon output pin 3 goes to the low logic state and then to the high logic state. IC2 will then pulse at the rate of 1 pulse every 5 seconds for as long as TRi 1 is on.

The output pin 3 is fed to the gate 10 of IC3 which reverses the pin 3 output conditions. Each time pin 3 goes to the low logic state the output of gate 10 of IC3 goes to the high logic state switching on TR6 and therefore energizing a mechanical counter.

When TR3 conducts this places a high logic state on gate 4 of the lC4. The output of gate 4 then goes to the low logic state. C10 therefore begins to discharge holding the gate 3 output at the low logic state and gate 11 output at the high logic state for 30 seconds. When C10 is discharged gate 3 output goes to the high logic state thus causing gate 10 output to go to the low logic state and gate 11 output to go to the high logic state.

When gate 11 output goes to the high logic state TR10 switches on to energise RL2. As gate 3 goes to the high logic state all control voltage to lC4, lC3 and IC1 is iost because the vehicle now slows down switching gates 10 and 11 of 1C1 to the logic high state. As a result of this TR10 must lock on even though gate 4 output has now gone to the low logic state. As gate 11 output goes to the high logic state this high logic state is placed on the input of gate 10 by D17 keeping gate 10 output at the low logic state and therefore gate 11 output at the high logic state. When the relay RL2 energises the normally open contact closes taking the input 4 to ground. This then causes the ignition coil to switch off thus preventing the spark plugs from firing. TR10 will remain on for as long as as TR8 is conducting. To enable the driver to restart the engine he must first switch off the ignition so removing power from input 3. C7 then discharges holding TR8 for one minute. As TR8 switches off the relay RL1 D energises and resets the lock at gate 10 and 1 1 of IC4. This subsequently switches the relay RL2 off. The engine can now be restarted and when gate 11 goes to the high logic state D8 switches on indicating that the engine has stopped.

Gates 10 and 1 1 form a latch circuit for the tamper indicator D22. The input to gate 10 must remain at the high logic state at all times to keep the latch inactive. When the ignition is on the input is kept at high logic state by the voltage through D20. When the ignition is off there is no voltage passing through D20. However, gate 3 output will be at high logic state thus keeping gate 10 input at high logic state. Gate 3 input is at low logic state because it is connected to the coil by input 4.

If the sensor cable is removed R44 will pull gate 3 input to high logic state by placing a low logic state on the input of gate 10 and activating the latch. The latch is then not affected by a further change at gate 10 input.

A digital counter circuit can be provided and reference is made to the drawing of such a circuit in Figure 2.

Whenever a digital counter is used TR6 operates in the same manner as previously described. This pulse is then conditioned by IC7 of the digital counter circuit shown in Figure 2 and fed to pin 12 of IC5. IC5 is a three digit primary coded decimal counter. The counter consists of three negative edge triggered binary coded decimal counters that are cascaded synchronously. The information is then time division multiplexed providing 1 binary coded decimal number at a time. Pins 1, 2 and 1 5 are fed directly to the three digit display D25, D26 and D27 as digit selectors. Pins 5, 6, 7 and 9 are fed to IC6. IC6 is a binary coded decimal to seven segment latch decoder driver. This integrated circuit drives the individual segments of all three displays. SW2 is a display working switch. In a normal position no display is shown.When SW2 is pressed the number of faults will be indicated.

Counter re-set is achieved when SW1 (see Figure 1) is placed in the Off position.

Thus it will be apparent that there is no direct mechanicai or other control of the engine but that the device serves as a training aid in effect to condition the drive to drive within preset parameters and also as a record of faults as defined by exceeding the preset limit.

As indicated in regard to the lights above the device preferably has a light which gives a warning if the electrical connections are tampered with. Preferably the whole circuit is embedded in polycarbonate resin or similarly encased and as will be noted solid state components are preferred.

This example relates to a spark ignition engine, but can be adapted to a diesel engine easily, e.g.

by having a magnet attached to the fuel injector drive shaft to cause pulses in an adjacent coil which would then act as a sender giving a signal whose frequency is proportional to engine speed.

Or for a diesel one could use a sensor system related to road speed, e.g. by means of a magnet attached to the propeller shaft, to modify the approach adopted.

Claims (11)

1. An aid for vehicle engine usage which is adapted to monitor the engine speed during running and primarily to provide warning signals or indications if the engine speed diverges from preset limits.

2. An aid for vehicle engine usage as claimed in claim 1, which is adapted to provide a temporary immobilisation of the engine if suitable corrective action is not taken by a driver after predetermined warnings have been given.

3. An aid for vehicle engine usage as claimed in either one of claims 1 or 2, adapted to retain and display for subsequent noting faults which have occurred during running being faults as defined by a predetermined degree of divergence from preset limits.

4. An aid for vehicle engine usage as claimed in any one of claims 1 to 3, which is programmable to any desired maximum engine speed.

5. An aid for vehicle engine usage as claimed in any one of claims 1 to 4, in which the signals include a buzzer, activated on infringement of the limit an amber light which displays a warning that the limit is being approached, a green light or lights which display that the engine is at a safe speed and a red light to indicate the limit is exceeded.

6. An aid for vehicle engine usage as claimed in any one of claims 3 to 5, in which a fault is defined as a period of five seconds in excess of a preset maximum speed and a fault display is adapted to display the number of five second periods which the engine is run in excess of the maximum speed.

7. An aid for vehicle engine usage as claimed in any one of claims 2 to 6, which comprises an engine cut-out which is adapted to immobilise the engine for a predetermined limit period after more than a certain time in excess of the maximum speed.

8. An aid for vehicle engine usage as claimed in claim 7, in which the cut out comprises a connection to an ignition coil of the engine and a relay adapted to close to connect the coil connection to ground.

9. An aid for vehicle engine usage as claimed in any one of claims 1 to 8, which includes a tamper memory, a deactivating switch, a tamper indicator and adapted to operate when specified components of the aid are tampered with.

10. An aid for vehicle engine usage as claimed in any one of claims 1 to 9, in which a slow switch on for the circuit is provided by an expacitive resistive discharge circuit so that power is supplied to the circuit after expiry of a time delay following switching on.

11. An aid for vehicle engine usage substantially as herein described and as illustrated in the accompanying drawings.