GB2307001A - Secure electrical connection for mechanical vehicle immobilizer - Google Patents

Description

1 Anti-theft device 2307001 The invention is based on a device according

to the generic type of the claim. A known device (EP-PS 232 974) of this type acts upon a shut-ollf valve carranged in the fuel supply fine of a vehicle in that a code testing device is associated with the actuator device of the shut-off valve, which code testing device only opens the valve after a release code has been supplied, thereby enabling operation of the vehicle. The actuator device and the code testing device are arranged directly on the valve in a common protective housing. The protective housing prevents mechanical access to the valve actuator device, whilst the code testing device prevents electrical access. This known arrangement thus effectively prevents unauthorised opening of the valve and therefore unauthorised starting of the vehicle. However, it requires sufficient structural space in the vehicle in the region of the shut-off valve for the accommodation of the protective housing with the actuator device and code testing device. It is precisely this space which is often not available, for example in the case of shut-off valves in diesel injection pumps which are arranged directly on the pump. In order to be able to use the proposed protection device in these cases, it is necessary to precisely adapt the geometry of the protective housing to the respective given spatial conditions. If the engine components which determine the structural space are: aniifwt=d in a wide range of types, then it is usually necessary to make available a correspondingly large range of protective housing types for the security device. As a result of the critical structural space conditions, the assembly of the protective housing on the valve is also usually impaired.

It is the object of the invention to provide an anti-theft device which ensures good security whilst occupying minimum structural space and which can be easily operated.

This object is attained by a device having the characterising features of 2 the main claim. According to the invention, the actuator device and code testing device are arranged in separate protective housings in two different locations on the housing surface of an engine aggregate whose function is influenced by the actuator device. Formed between the actuator device and code testing device in the housing is a shaft, in which the control line for controlling the actuator device is guided. The shaft is advantageously constructed as a bore formed in the housing wall. In a preferred embodiment the act device is easily accessible on the upper side of the aggregate, whilst the code testing device is on the underside of the aggregate facing the roadway. An anti-theft device designed in this manner offers the advantage that the actuator device can be of small structure and the available structural space can be fully exploited for the construction of the protective housing. Sufficient structural space is also available for the code testing device, so that the said device can be designed with a sufficiently strong protective housing. As a result of the fact that the connecting line provided between the code testing device and the actuator device is preferably laid within the housing wall of the aggregate in such a manner that it is practically inaccessible to an unauthorised person, it does not interfere with the security function. The particularly advantageous installation of the code testing device on the underside of an aggregate facing the roadway considerably impedes access and thereby advantageously increases the security effect of the whole device. Installation on the underside also offers the advantage that the code testing device can be mounted in a location which is always well-cooled. In order to further reduce the risk to the security function posed by the control line, the electrical circuitry thereof can be constructed in such a manner that any irregular linking of the connecting cable with the aggregate housing results in a short-circuit, which renders actuation of the actuator device impossible.

An embodiment of the invention will be explained in further detail in the following with reference to the drawings.

3 Figure 1 is a schematic diagram of the proposed anti-theft device, whilst Figure 2 is a on through the housing of an injection pump with a connecting line shaft formed therein.

Figure 1 shows an engine aggregate 20, on whose housing Outer side 10 an actuator device 13 is arranged, which effects a function essential for the operation of the aggregate 20. For example, the aggregate 20 can be an injection pump and the actuator device 13, as shown in Figure 1, can be a shut-off valve, which controls the supply of fuel K via a fuel supply line 18 to the aggregate 20. The actuator device 13 is enclosed by a sturdy protective housing 14, which is fixedly connected to the housing of the aggregate 20, so that unauthorised mechanical access to the actuator device 13 is prevented.

Located at a site on the housing outer side 10 of the aggregate 20 which is spatially separate from the position of the actuator device 13 is a code testing device 11. Like the acr device 13, the code testing device 11 is also enclosed by a sturdy protective housing 12 which is fixedly secured to the housing of the aggregate 20 and which rules out unauthorised mechanical access to the code testing device 11. A code evaluating device 17 is also connected to the code testing device 11 via a connecting line 16. The code evaluating device 17 can be an immobiliser, for example, which can be supplied with a code by a user, or an input device, via which a user can transmit a code directly to the code testing device 11.

The code testing device 11 and the actuator device 13 are connected to one another via a control fine 19. For guiding the control line 19, a shaft 15 is formed in the housing of the aggregate 20. One end of the shaft 15 lies within the protective housing 12 containing the code testing device 11, whilst its other end lies within the protective housing 14 enclosing the actuator device 13. As shown in the drawings, the shaft 15 is preferably constructed in the form of a bore formed in the aggregate 20. In order to form a bore having a sufficient diameter, the housing of the aggregate 4 can optionally be provided during manufacture with increased thicImess in the region of the bore. To further improve tampering security, the operation of the code testing device 11 and the actuator device 13 via the control line 19 is effected in such a manner that the control fine 19 lies at a higher voltage potential than the housing of the aggregate 10. In this respect, the control line 19 is encased in insulating material within the shaft 15. Improperly effected contact of the control line 19 with the housing of the aggregate 20, for example after enforced severance within the shaft 15, results in short-circuiting, which can be detected by the code testing device 11.

The code testing device 11 and the actuator device 13 cooperate in such a manner that a release of the fimction actuated by the actuator device 13 only occurs when the code testing device 11 is firstly supplied with a release code by the code evaluating device 17.

The actuator device 13 is expediently arranged on the upper side of the aggregate 20, so that it is easily accessible once the engine bonnet has been raised. At the same time, the code testing device is preferably mounted on the underside of the aggregate 20 facing the roadway, so that it is difficult to access without auxiliary means, for exanple can only be accessed from the underside or after removal of another vehicle component. The positioning of the code testing device 11 is expediently efflected in such a manner that it experiences constant cooling.

CLAB45 1. An anti-theft device for motor vehicles, with a code testing device arranged on an aggregate which is essential for the operation of the vehicle, said code testing device being connected via a control line to an actuator device, which influences the operation of the aggregate and whose fimction is only released by the code testing device when a release code is supplied, characterised in that the actuator device (13) and the code testing device (11) are arranged separately on the aggregate (20), and a shaft (15) for accommodating the control line (19) is formed on or in the aggregate (20).

2. A device according to claim 1, characterised in that the shaft (15) is constructed as a bore in the housing wall of the aggregate (20).

3. A device according to claim 1, characterised in that the actuator device (13) is arranged so as to be easily accessible on the upper side of the aggregate (20).

4. A device according to claim 1, characterised in that the code testing device (11) is arranged so as to be difficult to access on an underside of the aggregate (20) facing the roadway or the engine.

5. A device according to claim 1, characterised in that the control line (19) lies at a higher electrical potential than the housing (10).

6. A device according to claim 1, characterised in that the aggregate (20) is a fuel injection pump and the actuator device (13) is a shut-off valve.

6 7. An anti-theft device substantially as herein described with reference to the accompanying drawing.