| 摘要 |
705,632. Vehicle-theft alarms. POLUDNIAK, W. B. April 1, 1952, No. 8298/52. Class 118 (1). A vehicle theft alarm comprises a combination lock which, when released, allows an ancillary ignition-circuit switch to be opened and closed, but otherwise prevents closure of the switch if it is open and vice-versa, the ancillary switch when open connecting an electrically-operated alarm (e.g. the vehicle's horn) into a circuit comprising a further normallyopen switch which is closed upon movement of the vehicle bonnet or release mechanism therefor from its normal position. Fig. I illustrates the combination lock and ancillary switch, the circuit connections being shown in Fig. II. The lock comprises two rotatable discs 12 and 13, each having a cut away portion at one position on its periphery so that when they are set appropriately by the knobs 16, 17, the collar 14, mounted on a shaft attached to a knob 6, may freely pass the discs. As shown, the ignition circuit, comprising main switch 28, contacts 10 and 11, and ignition coil 34 is broken, the bridging member 2 which closes the circuit when the knob 6 is depressed, completing the circuit comprising the contacts 8 and 9. This circuit comprises a further subsidiary switch, Fig. VI, which is controlled by the bonnet-release mechanism of the vehicle. The bonnet is released by movement of the cable 46 which causes a bridging member 39 to connect terminals 35 and 36, and thus, when terminals 8 and 9 are also connected, to complete the circuit of the horn 32 and a solenoid 42. Solenoid 42 comprises a core 43 which is normally retracted as shown; however upon excitation of the solenoid the core 43 engages a cut-away portion of the member 39 thus preventing further movement of the bonnet-release cable. The circuit of contacts 8 and 9 also includes a gravity switch 49 containing mercury so that the circuit is completed if the vehicle is tilted, as for example by connecting it to a break-down lorry, means may be included for rendering this switch inoperative should it be desired to park on a steep slope. Fig. VII (not shown) illustrates a modification of Fig. VI for vehicles not using the bonnet-release mechanism described in which the bridging member 39 is attached directly to the bonnet so that any attempt to open the bonnet will result in the completion of the circuit and the operation of the alarm 32 and the bonnet-locking device. Further protection is provided by a circuit including the discs 12 and 13, the disc 12 being connected to the casing through a contact 23 and the disc 13 being connected to a contact 24. Should any attempt be made by an unauthorized person to depress the knob 6, the discs will be connected by the collar 14 and the alarm 32 sounded. The conductors from contacts 9, 11 and 24 pass within a metal tube 56, and a metallic conductor 58 is attached to the lead from contact 24 as shown. Thus should an attempt be made to cut the tube 56, the cutting tool will earth the leads thus completing the alarm circuit. Furthermore, if the whole device is unscrewed from its position within the vehicle in an attempt to remove it altogether, the conductor 58 will be drawn up against the tube 56, thus again completing the alarm circuit. A further locking, device and switch may be connected into the circuit to prevent unauthorized opening of the boot of the vehicle. Time switches or self-holding relays may be used in the circuit so that the alarm continues for either a predetermined time or until the ancillary switch is opened. |
