WO1988003884A1

WO1988003884A1 - An anti-theft device for a motor vehicle

Info

Publication number: WO1988003884A1
Application number: PCT/SE1987/000545
Authority: WO
Inventors: Ove Andersson
Original assignee: Ove Andersson
Priority date: 1986-11-26
Filing date: 1987-11-20
Publication date: 1988-06-02
Also published as: SE8605057D0; SE8605057L

Abstract

An anti-theft device for a motor vehicle, provided with a computer that emits requisite control signals to an operative unit. The anti-theft device operates on the code principle and comprises a code carrier (1), a code reader (2) and a code comparator which rejects or approves the code in the code carrier (1). The code comparator in the device is integrated in the computer (37) so that control signals to the operative unit are only generated if the code is correct.

Description

An Anti-theft device for a motor vehicle

The present invention relates to an anti-theft device for a motor vehicle, provided with a computer that continuously emits control signals to an operative unit in the motor comprising a code carrier, a code reader and a code comparator which rejects or approves the code in the code carrier.

As is known, numerous different locking or projection devices exist which are intended to prevent theft of an object or access to an area by unauthorized persons.

A particularly wide variety of devices exist which are intended to prevent vehicles or some equipment in the vehicle, such as a car radio, from being stolen. The most usual protection device, now fitted on almost all vehicles, is the key-operated ignition lock. When the key is inserted in the ignition lock and turned, a contact is closed which connects the starter to the battery. Unfortunately, such anti-theft protection has proved insufficient since the ignition-lock contact can easily be by-passed by connecting the wires directly between the battery and the starter. An experienced vehicle thief performs such an operation in an extremely short time.

To further impede the theft of vehicles, therefore, other types of locking devices of electrical or mechanical type have been added, e.g. steering-wheel locks. However, these measures have unfortunately not given the desired result either and this type of crime still constitutes a major problem for owners, insurance companies and police authorities. An example of an electronic theft-proof system can be found in WO 80/01477, for instance, where a code stored in a magnetic card is read in a code reader. If the code is correct a signal is emitted to the various elements in the vehicle, ^'"including the starter. This can then be activated in the normal manner using an ignition key or an ignition button. This system does indeed complicate the theft of a vehible when compared with the systems currently available but does not eliminate the risk entirely since, even if the logical unit emitting the signal can be located^" in a place difficult to reach such as under the bonnet, the starter can still be connected directly to the battery since the cable section between the switch controlled by the logical unit and the starter is freely accessible for connection to the battery.

DE-A-3 126 712 also describes a safety system comprising a key-operated ignition lock and a code device which, if the code is correct, effects contact between battery and ignition lock. Activation of the ignition lock will then connect ignition system and battery. This device has substantially the same drawbacks and deficiencies as the device described above, i.e. that a section of the cable supplying the ignition system with current is freely accessible for connection to the battery. This offers no great problem to an experienced vehicle thief.

The control system shown in WO 82/02861 suffers from substantially the same weaknesses as the anti-theft devices described earlier since here too a contact arranged in the ignition system can easily be by-passed.

The object of the invention is to effect an anti-theft system of the type described in the introduction, which is not marred by the drawbacks of the known technology and in which, therefore, the operative unit cannot be activated by by-passing the blocking member.

This object is achieved by the code comparator being integrated in the computer so that control signals are only generated at the computer output if the code is correct.

Since the code comparison is performed in the control computer and this is blocked.*unless the code is correct, the vehicle cannot be illicitly started by a simple by-passing of the device. The operative unit controlled by the computer may suitably consist of one or more elements in the injection system in an injection motor, e.g. the spark control or the injection motor. The code is then compared in the central unit of the computer.

One embodiment of the invention is described in the following with reference to the accompanying drawings, in which

Figure 1 is a schematic block diagram showing the control circuit in an injection system, designed in accordance with the invention,

Figure 2 is an exploded view of a key construction suitable for use with the system shown in Figure 1, in which the components included in the key are shown in various projections, and

Figure 3 shows a contact arrangement for sensing the contact points of the code carrier, seen from the front and from the side, respectively, and partially in section. The fuel injection system for a vehicle shown in block- diagram form in Figure 1 comprises a computer-controlled control circuit. The computer 37 comprises a central processing unit CPU, RAM memory and ROM memory. The sensor senses various running parameters such as speed 3, crankshaft position 4, quantity of air 5, intake-air temperature 6, engine temperature 7 and load range 8. A sensor is also provided for the position of the accelerator, this being connected via a wire 14 to the control circuit. The signals received from the sensors are transmitted to input 10 of the computer, possibly after signal processing (in impulse convertors, analog- digital convertors) . The signal-processing means are indicated by squares having a common designation 9 although in fact they are different units with different design. Depending on the input signals, the central processing unit CPU emits output signals which control the ignition 11, fuel injection 12 and fuel-pump motor 13, possibly via amplifiers or other suitable output signal processing means 15. Conventionally, the control system is activated by a start signal obtained when the ignition key is turned to operating position in the ignition lock. The start signal is thus trans¬ mitted through a wire which can easily be connected to the unit generating the start signal, by by-passing the switching contact in the ignition lock.

To eliminate this possibility, the start signal according to the invention is given in the form of a code which is compared with a code programmed into the memory unit in the central processing unit CPU of the control computer. If the code given agrees with that in the memory, the fuel control will be controlled in the normal manner. However, if the code is incorrect the central processing unit will be blocked so that no output signals are emitted. In the event of the code being incorrect, the central processing unit might also emit a signal to activate an alarm. The code may be programmed into the memory unit when the control circuit is manufactured. However, it is preferable for the correc code to be programmed in the first time the code carrier 1 is inserted into the code reader 2, whereupon the code transmitted will be determined in the memory unit of the computer as the correct code for future use. Since the code is first compared in the control computer and its output signals are blocked if the code is incorrect, the vehicle cannot be started by a simple by-pass and theft is thus effectively prevented.

The system according to the invention includes a code reader 2 and a code carrier 1. The code reader 2 communicates with the input 10 of the computer via wires 16.

The code carrier is suitably integrated in the ignition key. Figure 2 shows an example of how this can be achieved in practice. The key-head comprises several parts and can be pushed onto the key-bit. Of course bit and head could also be made in one piece, with the code carrier embedded in the head. The key-head comprises three main parts 17, 18, 19, two side pieces 17, 18 and a code carrier 19. When fitted together, the side elements 17, 18 form a pocket for the code carrier 19. One side element 17 is provided with a spring-ratchet 20 facing the other side element 18, while the other side element 18 is provided with a guide for the end of the key-bit 24, in the form of two straight, parallel flanges 21, 22 spaced from each other. This side element 18 is also provided with an additional straight flange 23, spaced from the flanges 21, 22 and perpendicular thereto. The key-bit 24 is provided with a through-hole 25 into which the spring-ratchet 20 snaps when the end of the bit, guided by the flanges 21, 2-2, is inserted into the key-head formed by the joined side elements 17, 18. Each side element 17, 18 is provided with, an opening 27, 28 for the contact points 29 and 30 of the code carrier 19. The code carrier is in the form of an inverted U with its contact points 29 and 30, respectively arranged at the end of the U-limbs. As shown in Figure 2, the contact points 29, 39 on the U-limbs are located on opposite sides and the key-head is therefore provided with corresponding openings 27, 28, The contact points 29, 30 are electrically connected to a circuit 31 in which the code is stored. The key-head is fitted together when the code carrier 19 is applied in the side element 18 where it is positioned by the flanges 21, 22 and 23. The second side element 17 is then placed on the first side element 18 with the ratchet 20 between flanges 21, 22, after which the two side elements are joined by welding, glueing or the like. The key-bit can thereafter be inserted into the head so that the ratchet 20 snaps into the opening 25, thus locking the elements in relation to each other. This operation need not be performed immediately. The key-bit and key-head may be stored as separate units and only be united upon delivery.

Figure 3 shows how the contact points on the code reader may be arranged around the ignition lock. A contact boss 34 is arranged on a spring-actuated ring

33 which can be turned in relation to the lock cylinder 32 of the ignition lock. This boss is provided with the same number of contact points 35 as the contact points 29, 30 in each opening 27, 28 of the key-head. When the key is inserted into the lock cylinder 32 and turned, the contact points 29 or 30 on the code carrier 19 will be brought into contact with the contact points 35 of the code reader. If the key is turned further, to start the engine, for instance, the contact points will remain in contact with each other. The contact points 35 communicate electrically with the code reader via a wire 36.

Another important advantage of the anti-theft device according to the invention is that gangs of thieves operating "professionally" by towing away parked vehicles to an undisturbed spot, getting them running and sub¬ sequently selling them, will now be forced to replace the actual control unit to allow the vehicle to be driven. This type of equipment is available from the manufacturer/ general agent/factory for a specific make of vehicle. It is thus easy to establish whether a vehicle is stolen by checking its chassis number. Current types of alarm, systems allow vehicles to be made operational without any difficulty and then sold.

The embodiment of the invention described above is applicable to a vehicle provided with injection motor, but of course the same principle can be applied to vehicles with carburettor and electronic ignition, in which case the control function according to the invention is integrated in the control system for the electronic ignition.

The locking principle described may also be used to prevent theft of other equipment, e.g. vehicle radios, vehicle telephones, or navigation systems which have recently come on the market. Such equipment is provided with a code-comparison circuit communicating with the code reader and including a memory in which a code can be stored. The memory is activated by the main code of the vehicle the first time it is used. The circuit thus controls the current supply to the equipment making it impossible to use except with the correct code.

Claims

C l a i m s

1. An anti-theft device for a motor vehicle, provided with a computer that continually emits requisite control signals to an operative unit in the motor comprising a code carrier (1) , a code reader (2) and a code comparator which rejects or approves the code in the code carrier (1), w h e r e i n the code comparator is integrated in the computer so that control signals to the operative unit are only generated at the computer output if the code is correct.

2. A device as claimed in claim 1, w h e r e i n the operative unit consists of the fuel injection in an injection motor.

3. A device as claimed in claim 1 or 2, w h e r e i n the code carrier is integrated in the head of the ignition key.

4. A device as claimed in claim 3, w h e r e i n the key-head consists of a separate unit which can be fitted on the key-bit (24) .

5. A device as claimed in claim 4, w h e r e i n the key-head comprises three parts joined together, i.e. two side elements (17, 18) and a code carrier (19) positioned therebetween.

6. A device as claimed in claims 3 - 5, w h e r e i n the contact points (35) of the code reader (2) are located radially outside the lock cylinder (32) of an ignition lock, the contact points (29, 30) of the code carrier (19) being located correspondingly in the key-head, so that they are brought into contact with the contact points (35) of the code reader (2) when the ignition key is turned in the ignition lock.