FR2652184A1 - PROTECTION SYSTEM, IN PARTICULAR FOR MOTOR VEHICLES, OF THE TYPE COMPRISING AN ELECTRONIC DEVICE FOR CONTROLLING AN ALARM DEVICE. - Google Patents

Abstract

The invention relates to a protection system. This system comprises an electronic control device (4) of an alarm device (5) and a lock (1) with key (2) mounted in a two-state electrical circuit electrically connected to said electronic device (4) and of which the two states are determined respectively by the presence and absence of the key in the lock, the establishment of one of said states putting the system under electrical voltage while in the other state, the system is inhibited. The system is characterized in that the lock (1) is separated from the location (6) of the electronic device (4) and connected to the latter by a bundle (3) of electrically conductive wires, which includes electrical connection wires. (11, 12) between the lock (1) and the electronic device (4) and advantageously a plurality of additional wires (15,16,17), and in that the ends of at least some (15) of these these are free at the level of the electrical connection zone (9) of the connecting wires (11, 12) to the lock. The inventlon can be used for motor vehicles.

Description

The invention relates to a protection system, in particular for vehicles

  automobiles, of the type comprising an electronic control device of an alarm device, adapted to trigger an alarm after detection of an alarm condition, and a key lock mounted in a two-state electrical circuit electrically connected to said device the two states are respectively determined by the presence and absence of the key in the lock establishing one of said states putting the system under electrical tension while in the other state, the system is inhibited. In known systems of this type, the electronic device is generally arranged inside a box. The lock is mounted on it so that the electrical connection device of the lock to said electronic device is also inside the box and is therefore inaccessible. However, it has proved advantageous to locally separate the lock and the electronic device and to arrange them at locations more or less distant from each other. Such an arrangement, however, has the major disadvantage that the device for electrical connection of the lock to the electronic device, when it is established by electrically conductive son becomes accessible, which makes possible unauthorized interventions for inhibition of electronic device and so the alarm device, reproducing the same conditions at the entrance of the electronic device that causes the

  set up the key in the lock.

  It is therefore an object of the present invention to provide a protection system which is adapted to provide security against such inhibitions.

authorized system.

  To achieve this purpose, the protection system according to the invention is characterized in that the lock is separated from the location of the electronic device and connected thereto by a bundle of electrically conductive wires, which comprises the electrical connection wires between the lock and the electronic device and at least one additional wire that does not interconnect the lock and the electronic device. According to an advantageous characteristic of the invention, the end of the additional wire is free at the level of the electrical connection zone of the wires

lock connection.

  According to another advantageous characteristic of the invention, at least two wires of the bundle are connected to one another in the aforementioned connection zone so as to form a closed loop connected at both ends to the electronic device and in that the latter is adapted to detect a break in the loop

and trigger an alarm.

  According to yet another advantageous characteristic of the invention, the bundle of wires is covered in the connection zone by a means forming a cover, so as to prevent access to this zone.

  and the distinction of the bonding wires in the beam.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory diagram which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention and in which: - Figure 1 shows schematically a protection system according to the present invention; and FIG. 2 is a detail view of a

  beam cut-off detector according to the invention.

  In its embodiment shown by way of example in FIG. 1, the protection system according to the invention comprises a lock 1 with its key 2, which is connected by a bundle 3 of electrically conductive wires to the electronic control device 4. of an alarm device 5. These two devices are only represented schematically. Indeed, their structure itself is not part of the invention. These are devices known per se. They are arranged in a location that is difficult to access in the vehicle and advantageously enclosed in a box indicated schematically at 6. The bundle 3 of electric wires

is arranged in a sheath 7.

  The lock 1 of which only the barrel is shown schematically is provided with a sleeve 8 which is fitted coaxially on the barrel and engages at its other end on the sheath 7 by delimiting an internal space 9 into which the sheath 7 which surrounds the wire bundle 3, of which two wires indicated at 11 and 12 are electrically connected to lugs 13 associated with the lock and constituting the connection terminals of an internal electrical circuit of the lock 1. This circuit is not represented in FIG. measure o its configuration does not fall within the scope of the invention. She is known in itself. It suffices to remember that this circuit is of the two-state type determined by the absence or the presence of the key 2 in the lock, where appropriate in a predetermined position. This too is known per se. The son 11 and 12 pass through the sheath 7 to the box 6 inside which they are connected

  by an assembly specific to the electronic device 4.

  As clearly shown in FIG. 1, the wire 11 is connected, on the one hand, by a resistor Ri to the device 4 and, on the other hand, by a resistor R2 to the control electrode of a switch member TR, such as a field effect transistor, for example of the N-MOS type. The wire 12 is directly connected to the source of the transistor TR, which is grounded. The control and source electrodes are interconnected by a capacitor C1. The drain of the transistor is connected to the electronic device 4. At the connection terminal of the resistor R1 to the device 4 is present a positive potential so that the circuit formed by the resistors R1 and R2

  and the capacitor C1 constitutes a delay circuit.

  The beam 3 further comprises wires 11, 12 of electrical connection a plurality of additional son. In the example shown, these wires are three in number. It can be seen that one of the three wires, indicated at 15, is connected at one end to the drain electrode of the transistor TR, while its other end, inside the cover sleeve 8, that is to say say in the connection zone 9 of the beam to the lock 1, is free, that is to say in the air. The two other wires 16 and 17 are electrically connected to each other at 18 in the zone of connection to the lock 1 of the wires 11 and 12. At their other ends, the wires 16 and 17 are respectively connected in box 5 at the

  mass and electronic device 4.

  The electronic device 4 comprises a circuit for detecting the state of the loop formed by the wires 16 and 17. This circuit is shown schematically in FIG. 2 and comprises a comparator advantageously realized in the form of an operational amplifier 20 of which the negative input is connected to the wire 17 via a resistor R3. This input is also connected, on the one hand by a resistor R4 to a positive potential and, on the other hand, by a capacitor C2 to ground. The positive input is connected by resistors R5 and R6 respectively to a positive potential and to ground. The output of the comparator 20 produces a signal, for example in the form of a transition from a logic state "1" to a logic state "0" following a detection of a change of state of the loop formed by the wires 17 and 16, for example produced by a

break of this loop.

  The operation of the protection system which has just been described will be described below.

referring to Figures i and 2.

  The electrical circuit associated with the lock 1 is adapted so that the presence of the key 2 in the lock, where appropriate in a predetermined position, causes the closing of the circuit, which corresponds to a short-circuiting of the wires 11 and 12 of the bond

  lock 1 electrical to electronic device 4.

  This state causes the inhibition of the electronic device and thus of the protection system. By against the removal of the key 2 of the lock 1 causes the opening of the lock circuit and the power supply of the protection system. It is easily understood that a shortcircuit of the connecting son 11, 12 at any point between the lock and the box 6 would then also produce the inhibition of the system. However, these wires are accessible and there is the risk that third parties unauthorized cut these son and, by short circuiting, inhibits the system. But, by providing in the beam 3 a number of additional son that are not electrically active, such as the wire 15, the aforementioned unauthorized person is obliged to combine the son with each other to successfully shortcircuit son 11 and 12. Since the ends of all the wires are hidden in the space 9 delimited by the sleeve 8, an identification of the active wires 11 and 12 from the terminal lugs 13 is excluded. In addition, all the son of the beam have the same appearance. It is also found that a general short circuit, due to the connection of the wire 15 to the drain electrode of the transistor TR restores the power supply of the system. By providing in the beam of the son 16, 17 which form a loop, a sectioning of the wire bundle would cause a break of the loop and thus a change of state thereof. This change will be detected by the circuit according to FIG. 2. Indeed, the output of the comparator 20 is in the high state as long as the loop is closed. For this purpose, the electric potential at the negative input of the comparator is negative with respect to the positive input whose reference potential is determined by the resistors R5 and R6. A break in the loop changes the potential at the negative input which therefore passes from its potential lower than the reference potential at the positive input to a level higher than the reference potential, which causes a change of state at the output of the comparator, which then passes from the high level to the low level, as shown schematically in Figure 2. This change of state is likely to trigger the alarm. It should also be noted that the setting of the key 2 in the lock 1 and thus the short-circuiting of the wires 11 and 12 with the aid of the key cuts the transistor TR only after a time delay predetermined by the time constant. of the delay circuit formed by the resistors R1 and R2 and the capacitor C1. Of course, the transistor TR is conductive when the key is not inserted into the lock. It should also be emphasized that in the absence of the loop formed by the wires 16 and 17, a sectioning of the wire bundle would have no effect on the

  system when the key is removed.

  It follows from the previous description that

  the invention is applicable to protection systems where the lock is separated from the remaining part of the system, this remaining part being in a location that is not very accessible. The invention makes it possible to remotely inhibit all the functions of the protection device which could be a device embedded on a vehicle. The bundle of electrical wires connecting the lock to the remaining part of the system is constituted in such a way that a cut made by means of an appropriate tool does not modify the state of the system, in the same way as a short circuit other than that of the two active wires 11 and 12 does not affect the state of the system. Among the many possible combinations between the different wires, a single combination, that is to say the short circuit of the son 11 and 12 allows the inhibition of the system. If the beam comprises a beam cut detection loop such as the loop formed by the son 16 and 17, this break, which in the example shown is a mass break, will cause a

  triggering the alarm device.

  Of course, many modifications can be made to the system according to the invention as described and shown. So the number of threads can be larger, which further increases safety

  of the system against unauthorized inhibitions.

Claims (9)

CLASS I CAT IONS   1. Protection system, in particular for motor vehicles, of the type comprising an electronic device for controlling an alarm device and a key lock mounted in a two-state electrical circuit electrically connected to said electronic device and the two states of which are respectively determined by the presence and absence of the key in the lock, the establishment of one of said states putting the system in standby while in the other state, the system is inhibited, characterized in that the lock (1) is separated from the location (6) of the electronic device (4) and connected thereto by a bundle (3) of electrically conductive wires, which has electrical connection wires (11, 12) between the lock ( 1) and the electronic device (4) and at least one additional wire (15, 16, 17) which does not interconnect the lock (1) and the electronic device (4).   Protective system according to claim 1, characterized in that the end of the additional wire (15) is free at the electrical connection area (9) of the connecting wires (11, 12). at the lock.   Protection system according to claim 1 or 2, characterized in that at least two wires (16, 17) of the beam (3) are connected (18) to one another in the connection zone ( 9) to form a closed loop connected at both ends to the electronic device (4) and in that the latter is adapted to detect a break in the loop and trigger an alarm.   4. Protective device according to one of   claims i or 2, characterized in that the beam   of wire (3) is covered in the connection zone (9) by a cover means, advantageously in the form of a sleeve (8), so as to prevent access to this zone and the distinction of the connecting wires ( 11, 12) in the beam (3), and in that all the wires of the beam have the same appearance.   5. Protective device according to one of   preceding claims, characterized in that the   wire bundle (3) is surrounded by a sheath (7).   6. Protective device according to one of   preceding claims, characterized in that it is   adapted so that a cut of the beam (3) is not considered to be a change of state of the circuit   electric associated with the lock (1).   7. System according to one of the claims   previous, characterized in that the electrical circuit associated with the lock (1) is adapted so that the presence of the key (2) in the lock (1) corresponds to a short circuit of the electrical connection wires (11, 12). mentioned above and in that the electronic device (4) is adapted so that the presence of the key (2) in the lock   is a condition of inhibition of the system.   8. Protection system according to one of the   preceding claims, characterized in that   comprises a detector circuit of the state of the electric circuit associated with the lock and electrical connection wires (11, 12), which is connected to the electronic device (4) and comprises a switching member (TR) such as a transistor of which the state is determined by the state said circuit and said wires.   Protection system according to Claim 8, characterized in that the detector circuit comprises a delay circuit (Ri, R2, C1) so that, when a short circuit is detected, the electrical connection wires (11, 12), inhibition occurs only after a delay of predetermined time.