GB2208953A - Security arrangements - Google Patents

Abstract

A security arrangement for electrically powered, alarmed, mobile units having an internal electric power supply 12 which connects 14, 16 to auxiliary or alternative external power supplies comprises an alarm actuating circuit 22, 29 adapted to detect disconnection of the unit from an auxiliary or alternative external power supply and to actuate alarm means 25 of the unit on detection of such disconnection. The unit may be a caravan, a boat or a hut. The arrangement gives a warning of theft of the unit. Circuit 22 detects the voltage existing between the neutral and earth conductors or an external a.c. mains power supply, which disappears when connection 14 is broken. Circuit 29 detects breakage of connection 16 to a d.c. voltage from e.g. a car battery. <IMAGE>

Description

SECURITY ARRANGEMENTS This invention relates to security arrangements for protecting mobile units such, for example, as caravans, boats, trailers, huts and the like which are internally electrically powered and which can be connected to auxiliary or external power supplies.

Such units can be alarmed, that is to say provided with intruder or smoke or fire and like alarms, but such alarms may not give protection against theft as by towing away of the entire unit.

The units may, however, usually be arranged to be connected to an external power supply, namely, in the case of caravans and trailers, a motor vehicle's d.c.

supply, usually through a conventional seven pin connector, when being towed and/or an external 110/220 volt a.c. mains supply when parked at home or on a caravan site or, in the case of boats, when moored or on hard standing. Connection to a motor vehicle's d.c.

supply might be made for energisation of tail-stop-lights and direction indicators while towing or for powering internal lights and on-board battery charging while standing. Connection to a.c. mains could be for battery charging through on-board rectifier or operation of internal services through rectified current.

The invention provides means by which the unit can be protected against unauthorised disconnection from such external power connection as would be necessary for theft by towing away the entire unit.

The invention comprises a security arrangement for electrically powered, alarmed mobile units having an internal electric power supply which connects to auxiliary or alternative external power supplies, comprising an alarm actuating circuit connectible to actuate alarm means of the unit powered by means of the internal electric power supply and adapted to detect disconnection of the unit from an auxiliary or alternative external power supply and to actuate said alarm means on detection of such disconnection.

The arrangement may be adapted to detect disconnection from an external mains a.c. supply having live, neutral and earth connections by detecting interruption of a neutral to earth loop.

The arrangement may be adapted to detect disconnection from an external d.c. supply connection providing two connectors closing an otherwise open detector circuit of the alarm actuating circuit, the circuit actuating the alarm means on said detector circuit going open.

Whilst the arrangement can be adapted to actuate alarm means separately installed in the unit, the arrangement may comprise integral alarm means.

The arrangement may be adapted for mobile units having connection for a.c. mains supply for charging an internal battery of the unit or operating internal services (whether by rectified or a.c. mains current) and also having connection for auxiliary d.c. supply by said alarm actuating circuit being adapted to detect disconnection of either connection when both are connected or of whichever connection is connected when only one of them is.

The arrangement may comprise disabling the means for disabling the alarm or the alarm actuating circuit and said disabling means may comprise security key switch means.

The arrangement may comprise a latching arrangement for latching the alarm means on, and may also then include a latch reset device.

The arrangement may comprise matching means matching said alarm actuating circuit to an external connection and actuating said alarm actuating circuit to actuate said alarm means in the event the circuit is connected to an unmatched external connection. Said matching means may comprise coded signal generating means and responder means responding to an incorrect signal by actuating said alarm actuating circuit. Said signal generating means may cyclically generate coded digital signals and said responder means may comprise means reacting to incorrect such signals, one of said signal generator means and said responder means being adapted for being on each of said mobile unit and a tractor unit to which said mobile unit can be connected, and the means adapted for connection to the tractor unit may be removable therefrom.In this way, the mobile unit cannot be connected to a tractor unit not fitted with the correctly coded responder. The coded signal generator may be adapted to output coded signals on detection of movement of the mobile unit; in the event of unauthorised movement while not connected to a tractor unit fitted with the correct responder (which can be removed when a tractor unit is left connected to the mobile unit, for security purposes) the alarm will sound in the mobile unit.

A simpler way of matching a mobile unit to a particular tractor unit is to have a plug and socket connection with a unique pin configuration.

Embodiments of security arrangements according to the invention will now be described with reference to the accompanying drawings, in which : Figure 1 is a view of a typical tractor/mobile unit combination; Figure 2 is a block diagram of one arrangement for a caravan or like mobile unit; Figure 3 is a block diagram of an ancillary arrangement; and Figure 4 is an illustration of a unique matching pin arrangement.

Figure 1 to 3 illustrate security arrangements for electrically powered, alarmed mobile units such as caravan 11 of Figure 1 which connect to auxiliary or alternative external power supplies. As shown, the mobile unit, caravan 11, has an internal 12 volt battery 12 and a rectifier 13 for recharging the battery 12.

The rectifier 13 is connected to an external mains connection 14 for connection via a trailing lead to a domestic power supply socket when the caravan 11 is at home or on a caravan park. The caravan 11 is assumed for present purposes to be alarmed as by a system depicted diagramatically at 15 which may be of any desired type but typically including a passive infra-red movement detector and a siren, all powered from the battery 12.

In addition to the connection 14, the caravan also has a connection 16 by which it is attached to the automobile 17 or other tractor unit for connection to the electrical system thereof for operating tail and stop lights and direction indicators (not shown) of the caravan 11, and also perhaps for recharging the battery 12 or for operating internal services (lights, television, refigerator perhaps) from the automobile's electrical system.

While a passive infra-red or other alarm system will detect a break-in to the caravan 11, and set off the alarm, it is possible the entire caravan could be unhitched from its tractor unit if necessary and towed away, without setting off the alarm.

The invention provides an alarm actuating circuit 21 which dperates the alarm if the mains connection at 14 or the tractor unit d.c. connection at 16 is broken. The mains and d.c. connections 14 and 16 need not be powered on for this to happen in the embodiment to be described.

The alarm actuating circuit 21 is shown in block form in Figure 2 and comprises a loop detector 22 detecting a voltage between the neutral and earth pins of the connection 14. Such voltage is present so long as the connection 14 is connected to the mains supply irrespective of whether the supply is switched on or off on the live lead. So long as the loop detector 22 detects this voltage it remains quiescent. On detection of loss of voltage, however, it outputs a signal to amplifier 23 which actuates a latch 24 connected to the alarm 25 which therefore sounds and remains sounding even if the plug is replaced in the connection 14.

A reset circuit 26 is provided to unlatch the alarm 25. A security key switch 27 fitted externally or at least conveniently on the unit 11 is operable to actuate a disabling switch 28 disconnecting the amplifier 23 from the latch 24.

The connection 16 is a standard 7-pin caravan connection which has two spare pins 16a, 16b. For present purposes these two pins are shorted to form a loop. A detector 29 is arranged to pass a low current through this loop and to detect when the current is interrupted, when it outputs a signal to the amplifier 23 as before.

The circuit 21 is powered from the caravan battery 12 which is charged from the rectifier 13 connected to the mains supply. The battery 12 is also recharged from the vehicle electrics through the connection 16 which powers internal equipment such as lights through leads 31.

Thus once connected at either connection 14 or 16, or both, and the key switch 27 operated to enable the latch 24, unplugging at either connection will actuate the alarm 25, which will be latched on, from the caravan's internal battery 12.

The circuit 21 may be supplied complete with leads, plugs and socket so that it can be readily installed without any special wiring requirements.

Of course, only one part of the circuit 21 need be used - for example, a camping trailer may have no rectifier but will have a d.c. connection for operating tail etc. lights and a battery from on site operation of internal lighting. Only the loop detector 29 will in this case be functional, and it may be desired to manufacture circuits for such purpose without the mains circuitry.

Added security may be had from the arrangements illustrated in Figure 3 and 4. Figure 3 shows an additional circuit 41 which generates a coded signal which connects e.g. through the spare pins 16a, 16b to a responder circuit 42 mounted in the vehicle. A movement detector 43 which detects any movement of the unit as a whole (which could for example be a magnetic device sensing changes in compass direction through a swinging compass needle or a Hall effect device) is connected to operate the latch 24 through an AND gate 44. If and so long as the responder 42 responds to the signal generator 41 with the correct signal, then the signal generator 41 gives no output to the AND gate 44.On disconnection from the vehicle with a correctly coded responder, and movement, both the signal generator and the movement detector give the same signal to the AND gate which then actuates the latch 24 to operate the alarm 25. Connection to a vehicle not having the correctly coded responder does not help - of course, the electrics need not be connected, for towing away, but would normally be in the case of a caravan, say, for the stop and direction indicator lights to function.

If the responder 42 is removable from the tractor unit, however, towing away the tractor/mobile unit combination will actuate the alarm in any event.

Figure 4 illustrates an arrangement which makes it difficult to connect a caravan to an unauthorised automobile in that the standard seven pin connector 51 of the tractor is uniquely matched to the plug 52 of the mobile unit as by having a unique pin configuration such as illustrated so that only the plug supplied with the connector will fit. This could also be done by having a specially uniquely shaped plug and socket arrangement after the fashion of a lock and key.

The arrangements illustrated in Figure 3 and 4 give additional protection in case the mobile unit has been left not connected to anything.

The arrangements described are, it will be appreciated, capable of adaptation to the protection of boats, trailers, e.g. camping trailers or road haulage trailers, and also to the protection of temporary huts e.g. on building sites, in addition to caravans. While a standard piece of equipment may be produced which can be readily connected to whatever external service or sevices may be present, different versions could be produced suitable for connection to a.c. mains only or to d.c. only as appropriate.

Claims (12)

1. A security arrangement for electrically powered, alarmed mobile units having an internal electric power supply which connects to auxiliary or alternative external power supplies, comprising an alarm actuating circuit connectible to actuate alarm means of the unit powered by means of the internal electric power supply and adapted to detect disconnection of the unit from an auxiliary or alternative external power supply and to actuate said alarm means on detection of such disconnection.

2. An arrangement according to claim 1, adapted to detect disconnection from an external a.c. mains supply having live, neutral and earth connections by detecting interruption of a neutral to earth loop.

3. An arrangement according to claim 1 or claim 2, adapted to detect disconnection from an external d.c.

supply connection providing two connectors closing an otherwise open detector circuit of the alarm actuating circuit, the circuit actuating the alarm means on said detector circuit going open.

4. An arrangement according to any one of claims 1 to 3, comprising integral alarm means.

5. An arrangement according to any one of claims 1 to 3, adapted for mobile units having connection for a.c. mains supply for charging an internal battery of the unit and also having connection for auxiliary d.c.

supply by said alarm actuating circuit being adapted to detect disconnection of either connection when both are connected or of whichever connection is connected when only one of them is.

6. An arrangement according to any one of claims 1 to 5, comprising disabling means for disabling the alarm actuating circuit.

7. An arrangement according to claim 6, said disabling means comprising security key switch means.

8. An arrangement according to any one of claims 1 to 7, comprising a latching arrangement for latching the alarm means on.

9. An arrangement according to claim 8, comprising a latch reset device.

10. An arrangement according to any one of claims 1 to 9, comprising matching means matching said alarm actuating circuit to an external connection and actuating said alarm actuating circuit to actuate said alarm means in the event the circuit is connected to an unmatched external connection.

11. An arrangement according to claim 10, in which said matching means comprise coded signal generating means and responder means responding to an incorrect signal by actuating said alarm actuating circuit.

12. An arrangement according to claim 1, said signal generating means cyclically generating coded digital signals and said responder means comprising means reacting to incorrect such signals, one of said signal generating means and said responder means being adapted for being on each of said mobile unit and a tractor unit to which said mobile unit can be connected and the means adapted for connection to the said tractor unit being removable therefrom.

Amendments to the claims have been filed as follows 1. A security arrangement for electrically powered, alarmed mobile units having an internal electric power supply which connects to auxiliary or alternative external power supplies, comprising or including an external d.c. supply, comprising an alarm actuating circuit connectible to actuate alarm means of the unit powered by means of the internal electric power supply and adapted to detect disconnection of the unit from an auxiliary or alternative external power supply and to actuate said alarm means on detection of such disconnection.