WO1997028338A1

WO1997028338A1 - Electronic central locking system

Info

Publication number: WO1997028338A1
Application number: PCT/GB1997/000258
Authority: WO
Inventors: John Phillip Chevalier
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-01-29
Filing date: 1997-01-29
Publication date: 1997-08-07
Anticipated expiration: 1998-07-29
Also published as: AU1552497A; GB9601708D0; GB2309481A

Abstract

An electronic central locking system comprising a plurality of locking devices controlled by respective electromotive means (Ma-Mg), each locking device having at least one electrical transducer (R1-R2) capable of generating a signal indicative of the state of the locking device, a common electrical signal line connected to receive all the transducer signals to generate a combined analogue signal, and a central electronic control circuit responsive to the combined analogue signal on the common signal line to determine the status of all the locking devices (Ma-Mg), and further responsive to a command signal to determine which electromotive means (Ma-Mg) to switch on or off and to provide corresponding power outputs along a power line or lines to at least one of the electromotive means, the transducers being selected such that the values of their respective electrical signals form a predetermined set of different values, whereby each of the possible values of the combined analogue signal is uniquely indicative of a corresponding combination of status of the locking devices.

Description

Electronic Central Locking System

This invention relates to an electronic central locking system which is particularly suitable for motor vehicles but can also be used in many other situations

Electronic control of electromechanical locking devices for example in motor vehicles, aeroplanes, boats, houses, and so on, facilitates control and improves the level of security and safety. Many central locking systems are bulky and costly and have been designed with little consideration for security and safety aspects.

The present invention is aimed at reducing the cost of electronic central locking systems especially in motor vehicles, and at improving the safety and security of such systems.

One example of a typical central locking system is disclosed in GB-A-2167482. In this example, cables link a central control unit to each separate door lock, both for powering the respective motors and also for monitoring the status of the locks This necessarily involves a large amount of parallel cabling. It has been proposed to use an electrical ' switchboard" for reducing the cabling to a degree, and this is sometimes referred to as a multiplex system, but such systems still require a large number of wires

The present invention provides:

An electronic central locking system comprising a plurality of locking devices controlled by respective electromotive means (Ma - Mg), each locking device having at least one electrical transducer capable of generating a signal indicative of the state of the locking device, a common electrical signal line connected to receive all the transducer signals to generate a combined analogue signal, and a central electronic control circuit responsive to the combined analogue signal on the common signal line to determine the status of all the locking devices, and further responsive to a command signal to determine which electromotive means to switch on or off and to provide corresponding power outputs along a power line or lines to at least one of the electromotive means, the transducers being selected such that the values of their respective electrical signals form a predetermined set of different values, whereby each of the possible values of the combined analogue signal is uniquely indicative of a corresponding combination of statuses of the locking devices.

The common signal line is used to convey information accurately as to the status of all the locking devices, for example all the door locks in a vehicle. It can also be used, with appropriate electrical transducers, to determine the status of other components such as an an ignition key on the steering column, and a door key mechanism and to convey a signal from a light switch. In a particularly simple and advantageous arrangement, the electrical transducers comprise simple resistors and mechanical switches, the resistors being connected in parallel to the common signal line so that actuation of any locking device causes the corresponding switch to close and to connect the corresponding resistor to the common signal line Very low currents can be used, with very low voltage levels, and very light duty switches, for example tactile switches. Accordingly, the monitoring arrangements and the cabling arrangements can be provided and assembled at greatly reduced cost.

Further, by detecting the status of each locking device, and providing reliable central control in response to detected electrical values, the risk associated with accidental actuation of the locking devices, for example due to a short circuit or to electronic or electrical malfunction or defect, is eliminated.

The central control circuit can of course be arranged to respond to a remote control device, for example using infra-red transmission. Further, the system can be combined easily with a conventional alarm system without the need for any additional wiring or installation of new contact points. Any unauthorised opening of the doors would automatically lead to a change in the position of one of the electrical transducers, for example the tactile switch, and to the production of a unique electrical signal which can be analysed by the control circuit to provides an appropriate aiarm response

The common signal line provideja unique signal for every possible combination of statuses of the locking devices and other devices being monitored. In order that the invention be better understood, a preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrams, of which:

Figure 1 is a schematic wiring diagram of an electronic central locking system for a motor vehicle;

Figure 2 is a schematic circuit diagram of the central control circuit of Figure 1;

Figure 3 is a diagram of a latch drive motor stall current sensor circuit, for the five locking devices of Figure 1, omitted from Figures 1 and 2, and

Figure 4 is a schematic wiring diagram of an alternative system.

As shown in Figure 1, the central locking system controls the following units: Five door latches; a filler cap catch; an engine compartment catch; a tail-gate light (omitted from Figure 1); door and vehicle hazard lights; a passenger compartment (P.C.) light; engine ignition (ignition key); engine immobiliser (EMU and fuel pump), non-system alarm (siren); system alarm (piezo-alarm); window winders and sun-roof. Three tactile switches are housed in each of the five door latches, and each tactile switch has an integral resistor with the value Rl , R2 or R3 as shown in Figure 1. The tactile switches and resistors constitute electro-mechanical transducers, and those with the value of resistance Rl indicate the state of locking (locked or unlocked); those with the resistance R2 indicate the state of the door (latched or unlatched); and those with the resistance value R3 indicate any infringement on the security of the vehicle when the vehicle is locked. Each resistor is connected in parallel, between a ground line and a common signal line, and these lines are combined in a cable which is connected to the control circuit.

The passenger compartment light (courtesy light) is connected to a relay switch at terminal P3 ofthe control circuit; the relay switch is shown on the right hand side of Figure 2 The interior control switch for the passenger compartment light is a tactile switch with a resistor R4, so that the status of the switch is conveyed to the control circuit along the common signal line The control circuit determines the duration for which the courtesy light may remain switched on

The ignition key is associated with another tactile switch with a resistance R5 This switch is actuated as the ignition switch is moved between an ante-ignition and a post-ignition position. The control circuit prevents the starting of the engine if any one of the doors is unlatched, and it unlocks the doors only if they have already been locked by means of the interior control knob more than 10 seconds from starting the engine

A tactile switch with a resistance R6, labelled "interior lock" in Figure 1, is provided to lock or unlock the doors from the inside of the vehicle and to unlock the doors after they have been locked mechanically by means of the interior lock control knobs The switch operates by sending the appropriate signal along the common signal line to the control circuit.

Correspondingly, a tactile switch with a resistance R7 is provided to activate or deactivate the non-system alarm and immobiliser. It can only be actuated by means of the key mechanisms

The petrol filler cap has an actuator motor Mf for its catch, and the engine compartment catch, or bonnet latch, also has an actuator motor Mg

As shown in Figure 3, each of the five door latches has a power drive motor controlled by a stall current sensor circuit with a resettable relay switch

A typical value for the signal carrier current between the common signal line and ground is a constant current of 15 mA Each latch actuator is operated with an impulse current of five amps, protected with a re-armable fuse

The control circuit controls the sequencing of the polarity of power provided to each motor Upon receipt of a signal indicative of locking or unlocking of the latch, the polarity of the power supply current A is reversed, and the current A is supplied to the actuator motors, all at the same time, for 300 milli seconds.

The control circuit contains a Micro Processor, figure 2 which is programmed to determine the status of every locking device and other device which is associated with a tactile switch with one of the predetermined resistance values. Its determines the difference between the signal and the ground line voltage. More particularly, the Micro Processor is programmed to analyse sequences of this voltage difference. The voltage difference will be a function of the total resistance, whose reciprocal value is equal to the sum of the reciprocal values ofthe individual switch resistances. The individual values of the resistances are selected so that every possible combination of statuses of the switches gives rise to a unique combined resistance value. By way of example, operation of a door key mechanism, for locking or unlocking control, causes a resistance Rl across the signal line and ground line, and the Micro Processor recognises this as "10k" After locking or unlocking has been effected, all four main compartment doors will have been changed to the different status, so that four resistances Rl in parallel will be connected, and the Micro Processor would recognise this as a "20k" signal. The door handles are associated with resistors of value R3, which control the passenger compartment light and alarm; any one of these gives rise to a signal recognised as "30k". The internal switch with a value R4 for the passenger compartment light gives rise to a signal recognised as "90k". The ignition control, determined by an ignition key switch with the value R5, gives a signal recognised as "1.00k" The interior lock control knob associated with a switch with the resistance value R6 would be recognised as "110k". Alarm control is provided by a door key mechanism with a resistor value R7, recognised as "120k". In this example, the resistors shown in figure 1 as R2 are in fact selected as different resistance values R2a, R2b, R2c, R2d and R2e, and operation of these switches is recognised respectively as "40k", "50k", "60k", "70k", and "80k".

Typical resistor values are in the range of 10Ω to 3kΩ and typical currents on the signal line are between 1mA and 20mA. By way of example, various different combinations of switch status will now be considered: each can be recognised separately by the Micro Processor, which can then determine the appropriate action. Locking Status

With the system locked, the non-system alarm on and the passenger compartment hght off, no signals are provided Also, with the system unlocked, the non-system alarm off and the passenger compartment light switched on for a limited period of time, again no signals are provided

Engine Status

The engine can be turned on, and the system detects the value "100k" first The non system alarm is off and the passenger compartment light is off The engine cannot be started with any other signal

Key Mechanism Signals

To unlock the system, the non-system alarm is first neutralised and the immobiliser system deactivated Thus first the value of " 120k" followed by " 1 Ok" is necessary, and immediately after energising the actuator motors the value "20k" and directly afterwards the value "120k" once again is required This signal sequence is referred to as the "unlocking sequence" This command causes the system alarm to provide two bleςps in one second, it turns the non-system alarm off and the immobiliser off, and it switches the passenger compartment light on for 10 seconds

To lock the system, it is necessary to activate the non-system alarm and to reactivate the immobiliser The system must first detect the value of " 120k" followed by " 10k" and immediately after energising the actuator motors the value "20k" and directly afterwards the value "120k" once again The system must detect the same sequence of signals as with unlocking the system, except that the time factor effects the difference This is referred to as the "locking sequence" The system alarm sounds for one bleep in one second, the non-system alarm is switched on, the passenger compartment light is switched on for 10 seconds only, the immobiliser is switched on, any window winder that is down is actuated to lift up, and the sun roof, if open, will be closed

Although it is possible to lock one of the latches mechanically, no locking is possible if any of the doors is still unlatched, i e at least one of the values 40k, 50k, 60k, 70k, or 80k has been detected only once. The system is activated first into locking and immediately back into an unlocking position to the exact previous status The system alarm then sounds for a limited period of time, for example four bleeps in one second

For the system to lock in the intended manner, each of values 40k, 50k, 60k, 70k and 80k must be detected twice If any of them was detected once, the system will operate in the default mode, it implies that at least one of the doors was opened and not properly shut This door can be visually identified by providing a signal to an LCD screen if necessary The Micro Processor can identify any door which has been unlatched and relatched, by identifying its distinct resistance value twice

Non-Svstem Alarm and Door Handle Signals

The non-system alarm is comprised of the siren, hazard lights and passenger compartment light. In order for an infringement situation to be recognised, the doors must first have been locked by either the key mechanism or the remote control device Actuation of any of the door handles would cause a signal "90k", and this would set the alarm off for a limited period of time, the passenger compartment light for 30 seconds, the non-system alarm for 30 seconds, the hazard lights flashing twice per second for 30 seconds; and the siren bleeping six times in one second.

Locking the Doors bv means of the Interior Lock Control Knob

This can be effected either mechanically, by actuation of the interior lock control knob on any of the doors, giving rise to a signal value of "10k", or electrically by depressing the tactile switch labelled "interior lock" with the value R6, giving a signal value of "110k".

If at least one of the doors is unlatched, the system will not respond electrically and mechanically it will follow the sequence described above under the heading "key mechanism signals" The doors will be actuated first into locking and immediately back into unlocking, to the exact previous status The system alarm will sound for a limited period of time at four bleeps per second Unlocking the doors by means of the interior lock control knob can be effected either electrically, by pressing the tactile switch with the value R6, or by means of the ignition key (signal value "100k"); or mechanically by actuating any of the interior door lock control knobs (signal values "10k")

Passenger Compartment Light

This light is switched on for a limited period of time whenever one of the door handles is used, and the system has detected the value "30k" It is switched on for an indefinite period of time by operation of the tactile switch "p c light" with the value R4, when the system detects the value "90k" The tactile switch with the value R4 causes the Micro Processor to switch the light off if it is already on, upon actuation of the switch a second time

Starting the Engine

This is possible only if all the doors are fully latched: the system has to detect the value of "100k" once The passenger compartment light is switched off

To start the engine when the doors are locked by the interior lock control knob, the system detects the value of "100k" once It then moves the doors into the unlocked position 10 seconds after ignition has taken place The passenger compartment light is switched off immediately after ignition

Once the ignition key is turned off, the system will see the signal "100k" once again It turns the passenger compartment light on again immediately

Starting the engine is impossible following any other signal, and recognition of any other signal causes the system alarm to sound, for four bleeps in one second

Remote Control Signals

The infrared remote control device communicates via the infrared receiver with the control circuit It can cause the latches to unlock or to lock When this is recognised by the Micro Processor, unlocking the latches switches the non-system alarm off, the passenger compartment light on, and the immobiliser off. Locking of the latches switches the non-system alarm on. the passenger compartment light off, the 10

2 Front Doors, 1 Rear Door (4R2+1R5+R6+4R4+R7)

2 Front Doors, 2 Rear Doors (4R2+R6+4R4+R7)

Tailgate (4R2+2R3+2R5+4R4+R7)

1 Front Door, Tailgate (4R2+1R3+2R5+4R4+R7)

1 Rear Door, Tailgate (4R2+2R3+IR5+4R4+R7)

2 Rear Doors, Tailgate (4R2+2R3+4R4+R7)

1 Front Door, 1 Rear Door, Tailgate (4R2+1R3+1R5+4R4+R7) 1 Front Door, 2 Rear Doors.Tailgate (4R2+1R3+4R4+R7)

Non-Svstem Alarm & Door Handle Signals

Non-System Alarm, i.e. the Siren and Hazard Lights together with the passenger compartment light can be activated: using any of the outside door handles

(5R1+2R3+2R5+R6+3R4+R7) using the tailgate knob

(5R1+2R3+2R5+R6+4R4)

Locking the System bv Means of the Interior Lock Control Knob

Electrically while Ignition Key is in position one by means of depressing switch RIO

(5R2+2R3+2R5+R6+3R4+R7+R10)

Mechanically (Knob) (4R2+2R3+2R5+R6+3R4+R7)

To unlock the system

By means of the Ignition Key (5R1+2R3+2R5+R6+3R4+R7+R9)

Electrically by means of depressing switch RIO,

(5R1 +2R3+2R5+R6+3R4+R7+R10)

Mechanically (Knob) (4R1+2R3+2R5+R6+3R4+R7)

Mechanically (inside door handle) (4R1+2R3+2R5+R6+3R4+R7) 9 immobiliser on, and any window winder that is down, lifted up, and the sun roof closed if open

Immobiliser

The immobiliser is on only when the system is locked by means of either the remote control mechanism or the key mechanism The immobiliser switches off the EMU, the fuel pump and the ignition circuit (the starter circuit is disconnected) The system will not recognise any other signal again except the unlocking signal derived either from the remote control device or the key mechanism

In an alternative central electronic control system shown in figure 4, the various resistance values Rl to RIO are disposed slightly differently The system is programmed to recognise, amongst other combinations, the following unique signal levels from specific combinations of resistances as indicated in brackets

System status (including Locking Unlocking)

System Locked (5R1+2R3+2R5+R6+4R4+R7)

System Unlocked (5R2+2R3+2R5+R6+4R4+R7)

Engine Status

Engine On (5R2+2R3+2R5+R6+4R4+R7+R9)

Engine Off (5R1+2R3+2R5+R6+4R4+R7)

Key Mechanism Signals

To unlock the system (4R1+2R3+2R5+R6+4R4+R7)

To lock (4R2+2R3+2R5+R6+4R4+R7)

1 Front Door (4R2+1R3+2R5+R6+4R4+R7)

2 Front Doors (4R2+2R5+R6+4R4+R7)

1 Rear Door (4R2+2R3+1R5+R6+4R4+R7)

2 Rear Doors (4R2+2R3+R6+4R4+R7)

1 Front Door, 1 Rear Door (4R2+1R3+1R5+R6+4R4+R7) 1 Front Door, 2 Rear Doors (4R2+1R3+R6+4R4+R7) Passenger Compartment Light On for a limited period of time

Using any of the outside door handles (5R2+2R3+2R5+R6+3R4+R7)

Using any ofthe inside door handles (5R2+1R3+2R5+R6+4R4+R7)

(5R2+2R3+1R5+R6+4R4+R7)

Passenger Compartment Light On for an indefinite period of time

Depressing Tact Switch R8 once lx(R8)

To override depress Tact Switch R8 twice 2x(R8)

Starting the Engine

Starting the engine is only possible if all ofthe doors are fully latched and the system is in an unlocked position.

To start the Engine. (5R2+2R3+2R5+R6+3R4+R7+R9)

If the system is locked it moves into an unlocked position and the passenger compartment light is switched Off

(5R1+2R3+2R5+R6+4R4+R7+R9)

If engine is Off (5R1+2R3+2R5+R6+4R4+R7) the Non-System Alarm is always On

Remote Control Signals

To unlock the latches (5R1 +2R3+2R5+R6+4R4+R7)

To lock the latches (5R2+2R3+2R5+R6+4R4+R7)

Immobiliser

The Immobilisor is On only when the system is Locked

(5R1+2R3+2R5+R6+4R4+R7) It will be appreciated that there are significant sources of electromagnetic interference in a motor vehicle, particularly the moving components under the bonnet, but also of course the latch motors in each door The system is designed to minimise the effect of such interference on the low voltage, low current analogue signals on the common signal line By arranging the signal line closely adjacent the ground line, in the same cable, the signal spikes from interference should occur in both lines The control circuit includes filters for high frequency noise, at the terminals of each o the signal and ground lines After filtration, a differential amplifier senses the voltage between those lines, which is buffered by an integrated circuit and then fed to an analogue to digital converter for subsequent processing

In some cases, the interference locally in the vehicle will be so great as to mask the effect of the low voltage signal on the signal line

This can be overcome by designing the system with compensating monitoring circuits located in the motor vehicle close to the sources of interference, and in tandem with the signal line Each such auxiliary monitoring circuit consists of an amplifier responsive to the presence of the low power analogue signal on the signal line at the specific location ofthe major interference The amplifier has a substantially higher voltage output than the corresponding signal line voltage, and it provides an output signal of fixed duration to the control circuit, either on separate cabling or, more preferably, on the same signal line

The output level of the amplifier is predetermined and unique to that amplifier, so that the origin of the signal, for example for a specific locking device, can be determined uniquely by the microprocessor When the microprocessor performs its computation to determine the origin of signals from multiple locations, from the combined level on the signal line, it is programmed to take account ofthe amplified level; it responds in the same way as if the interference were not present, and the full resistance value from the corresponding tactile switch were present on the signal line This determination by the microprocessor can be assisted by the time delay introduced by the local amplifier, so that the microprocessor is programmed to distinguish between the original low power signal and the delayed output from the amplifier Thus, in addition to protecting the inputs and outputs of the control circuit by employing filters and transient suppressers the control logic can be programmed to recognise signals that have a predetermined value and to treat all other signals outside the predetermined ones as neutral. However, this alone may not be sufficient to guarantee the functionality of the system as there may be situations whereby the intended signal is incapable of reaching the control circuit due to various types of electrical noise There is also a danger of spurious signals being falsely interpreted by the control software as valid signals

In general, the tactile switches that may be used in the system are designed to handle a current intensity up to 50 mA Thus it may be necessary to provide adequate protection on the signal line in addition to the above-mentioned means At least one the surge protector circuit may be placed conveniently on the signal line and an amplifier circuit placed near the source of the predetermined signal (the revelant tactile switch) The amplifier circuit may designed as described above in relation to the compensating monitoring circuits

This protection against transient overvoltage caused by electrical storms (lightning), motor inrush and stall currents, etc, is intended to limit the impact of irregular voltage potential that may confuse the control logic

The surge protector circuit may be of the type normally used to protect data lines This can be used to guard against ground loops (ground potential differences, i e the currents between two grounded points) This may be done by converting the analogue signals to light pulses and then back again (with a time difference) to either analogue or digital form

It will be understood that the examples given above can be modified in many ways, within the scope of the invention as defined in the Claims For example, capacitors or coils or active semiconductor devices could be used in place of, or in addition to, the simple resistors. Any other electrical or electronic component could be used in the signal line, provided it gave rise to a unique electrical value on the signal line Whilst the systems described have only one signal line and one ground line, a number of such systems could be installed in the same motor vehicle, for example in different regions, and this would assist in distinguishing the origins of the signals, albeit at the expense of some extra cabling As indicated at the beginning of the description, the circuit could be applied in other situations where central electronic control of actuators or the like is required

Claims

CLAIMS:

1. An electronic central locking system comprising a plurality of locking devices controlled by respective electromotive means (Ma - Mg), each locking device having at least one electrical transducer capable of generating a signal indicative ofthe state of the locking device, a common electrical signal line connected to receive all the transducer signals to generate a combined analogue signal, and a central electronic control circuit responsive to the combined analogue signal on the common signal line to determine the status of all the locking devices, and further responsive to a command signal to determine which electromotive means to switch on or off and to provide corresponding power outputs along a power line or lines to at least one of the electromotive means, the transducers being selected such that the values of their respective electrical signals form a predetermined set of different values, whereby each of the possible values of the combined analogue signal is uniquely indicative of a corresponding combination of statuses of the locking devices.

2. An electronic central locking system according to Claim 1. in which the electrical transducers comprise simple resistors and mechanical switches, the resistors being connected in parallel to the common signal line so that actuation of any locking device causes the corresponding switch to close and to connect the corresponding resistor to the common signal line.

3. An electronic central locking system according to Claim 2. in which each switch is a tactile micro-switch.

4. An electronic central locking system according to Claim 2 or 3, in which the resistance values of the simple resistors are spread between about 10 Ω and about 3 kΩ

5. An electronic central locking system according to Claim 2, 3 or 4, in which the control circuit is arranged to provide a sensing current along the common signal line of between 1 mA and 20 A

6. An electronic central locking system according to any preceding Claim, comprising at least one auxiliary monitoring circuit connected to the control circuit and adapted for positioning remote from the control circuit in use, arranged in parallel with the said common signal line and comprising an amplifier responsive to the presence of the signal from the respective transducer to provide an output signal, at a substantially greater level than that on the common signal line, to the control circuit, the level of the output signal being unique to that amplifier, and in which the control circuit is arranged to determine from the same amplified output signal level the identity of the corresponding locking device

7 A motor vehicle fined with an electronic central locking system according to Claim 6, in which at least one source of electromagnetic interference to the common signal line is compensated for by a corresponding one of said auxiliary monitoring circuits, whose amplifier input is taken close to the electromagnetic interference source in the motor vehicle

8 An electronic central locking system according to any of Claims 1-6, or a motor vehicle according to Claim 7, in which the transducers are connected between the said common signal line and a ground line, the said signal and ground lines are wires arranged in close proximity, and the control circuit detects the voltage difference there¬ between so as to minimise the effects of electromagnetic induction on the wires