GB2144249A

GB2144249A - Anti-theft device

Info

Publication number: GB2144249A
Application number: GB8320609A
Authority: GB
Inventors: George Batey
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-07-30
Filing date: 1983-07-30
Publication date: 1985-02-27
Also published as: GB8320609D0

Abstract

A combination switch has a keyboard for entering a series of items of information for setting of the "combination". The items are received and stored in a micro-chip memory circuit. A control switch, provided for inclusion in any external electrical circuit to be controlled, is connected to the memory circuit. The memory circuit and the control switch can be put into a "setting" mode for initial insertion of a desired combination, and into an "operational" mode. Once a series of items has been entered into the memory, each subsequent entry of that series of items, and only that particular series, by use of the keyboard will cause the control switch to change its state. The combination switch may be incorporated in, for example, a fuel feed line or in a hydraulic braking system of a motor vehicle. <IMAGE>

Description

SPECIFICATION Anti-theft device This invention relates particularly to the field of anti-theft devices for motor vehicles and air and water craft, but is applicable broadly to the prohibition of control of any fluid-flow system except by an authorised user.

A first object of the invention is to provide an improved form of switch, for incorporation in antitheft and like immobilising devices, which can be pre-set with a combination of items of information known only to an authorised user, and will thereafter only operate, e.g. to close a circuit, when that same combination of items is entered.

A second object of the invention is to provide an arrangement for control of fluid flow utilising such a switch.

According to a first aspect of the invention a memory combination switch comprises a keyboard by means of which a user can "enter" a series of items of information, such as a multi-digit number, a micro-chip memory and switch circuit which is constructed such that it is possible to enter a series of items of information into its memory and such that its switch can only be actuated by again entering that same series of items, and means for setting the memory and switch circuit into a "setting" mode for entering the items to be memorised, and into an "operational" mode for subsequent switching operations.

In a convenient form, the memory combination switch comprises a housing having a panel with a number of finger-operable keys ortouch switches, a pair of output terminals across which a circuit is completed when the correct combination is entered, and a further control, such as a key-operable switch, for placing it in "setting" or "operational" mode. The whole may be battery operated, e.g. by one or more primary cells inserted into an appropriate compart mentofthe housing. Such a construction may then be used as a small and convenient switch module for incorporating in any electrical circuit in which control is required. The keyboard is advantageously remote from the memory and switch circuit.

According to a second aspect of the invention, a control circuit for a flow of fluid comprises (i) an electrically operable fluid flow valve, (ii) means for connecting the circuit to a source of current, and (iii) a memory combination switch, of the kind set forth above, arranged for completion of a current flow circuit th rough the fluid flow valve.

Where it is desired to have control of a fluid flow which is normally flowing, the flow control valve is arranged to be loaded towards "off" condition, but to be electrically energisable to permit flow of fluid.

By way of a first example, the flow control valve may be arranged in a fuel feed pipe of a motor vehicle The flow control valve, in rest condition, will tend to cut off the fuel supply. When the memory combination switch is properly actuated by insertion of the correct coded information a current feed circuit to the flow control valve is completed and the valve remains open to permit normal use of the vehicle.

In a second example, the flow control valve is used in one leg of a two-leg supply circuit for brake fluid between a master cylinder and one or more slave cylinders, e.g. for a vehicle braking system. The other leg of the supply conduit contains a non-return valve. So long as the flow control valve remains open, i.e. under the control of the memory switch, the two-leg conduit permits flow of fluid in both directions for normal operation of the braking system. If the flow control valve remains closed, the non-return valve ensures that the valve remains locked on after a first time of operation.

In order that the nature of the invention may be readily ascertained, some embodiments of anti-theft devices for vehicles, incorporating the combination switch of the invention, are hereinafter particularly described with reference to the Figures of the accompanying drawings, wherein; Figure 1 is an elevation of a basic memory combination switch unit; Figure 2 is a circuit diagram of an arrangement for controlling fuel feed in a motor vehicle; Figure 3 is a circuit diagram of an arrangement for controlling a braking system of a motor vehicle.

Referring to Figure 1, the basic combination switch device comprises a housing 1 having on its front face a keyboard zone 2 provided with a plurality of keys 3.

In the example shown there are ten such keys, marked with numerals "1 - 9". Any other convenient number of keys and other convenient marking, say alphabetical, could likewise be used.

Within the housing there is arranged a conventional micro-chip electronic circuit incorporating a power source, a memory and a switch. The micro-chip circuit is designed so that it can be programmed with a pre-selected series of items of information which can be entered into the memory by use of the keys 3.

In brief, the user selects, say, a five-digit number which he can remember. He places the circuit into a "setting" mode of operation, by use of a key entered into the keyhole 4 to operate one or more switches, and then punches in his five-digit number on the keyboard. This number becomes entered in the memory, and the user then removes the key from key 5. The circuit has output terminals 6 and the circuit arrangement is such that whenever the keyboard is used to punch in that same five-digit number, a circuit is completed through the terminals 6. No other combination of digits will produce the same result.Advantageously, there may be provided another pair of terminals 7 which are arranged in an alarm circuit, with the result that any attempt to enter an incorrect five digit number on the keyboard will always result in completion of the circuit of terminals 7 but not of the circuit at terminals 6.

The terminals 6 thus become a switch which can be used in, for example, either of the circuits shown in Figues 2 and 3.

In Figure 2 the switch described in relation to Figure 1, and now referred to for convenience as the memory-switch (M-S) is incorporated in a current feed circuit comprising a source of current 8, such as the usual 12-volt supply of the vehicle, and a motorised (i.e. electrically-openable against return loading) valve 9. The valve 9 is disposed in a feed line 10 of the vehicle.

The arrangement of the valve 9 is that it remains closed, and thus cutting off the fuel supply, at all times unless it is energised. To energise the valve 9 it is necessary to complete the current circuitry by correct actuation of the memory switch M-S. Accordingly, no person but the authorised user, in possession of the operating code, can open the valve 9 to obtain fuel supply to the vehicle. To enhance the security of the system, the motorised valve 9 can be incorporated on or in the usual electric fuel pump and disposed within the fuel tank, so that tampering from the exterior, at least in a short space of time, is impossible.As a further refinement, the same circuit may be provided with an "off" switch 11 which the user can operate manually at the time of leaving the vehicle, that switch having a "hold" arrangement which is energisable by the memory switch M-S, so that the memory switch need only be used momen tartly to cause the closing of the "off" switch which will then hold itself on until physically switched off by the user.

Referring now to Figure 3, there is shown an arrangementforcontrol ofthe braking system of a vehicle.

The conventional master braking cylinder feeds a split conduit 13a, 13b. The conduit 13a leads through a non-return fluid valve 14 to a common feed conduit 15 for one or more slave cylinders 16. The conduit 13b leads through a motorised valve 17, similar to the valve 9 described in relation to Figure 2, to the common conduit 15. So long as the motorised valve 17 remains open, brake fluid under pressure can flow in both directions between the master cylinder 12 and the slave cylinder(s) 16, and operation of the braking system is normal. If the motorised valve 17 is allowed to close, and thus block off the conduit 1 3b, any single subsequent operation of the master cylinder 12 will cause brake fluid to flow, under pressure, to operate the slave cylinder(s) 16, but there will be no return flow path available for relief of braking pressure. Thus, the brakes will remain locked on and the vehicle accordingly effectively immobilised. The motorised valve 17 is arranged on a circuit similar to that shown in Figure 2, and accordingly the proper operation of the braking system can only be obtained by the authorised user who uses the correct code and obtains energising of the motorised valve.

Claims

1. A combination switch comprising a keyboard having a plurality of manually-operable switch means for the entering of a series of items of information, a micro-chip memory circuit connected to said switch means to receive and store the entered series of items, a control switch for inclusion in an external circuit to be controlled, said control switch being connected to the memory circuit, the control switch and the memory circuit being so arranged that the control switch will change its state only upon the subsequent entry of a series of items already stored in the memory, and means for entering the memory circuit and the control switch into a setting mode for initial entering of a series of items into the memory circuit, and into an operational mode for change of state of the control switch at each occasion of subsequent entry of that series of items.

2. A combination switch, as claimed in claim 1, comprising a housing having a panel with the plurality of manually-operable switch means, a pair of output terminals accessible from the exterior of the housing and connected to the control switch such that a circuit is completed across said terminals whenever the control switch changes its state as a result of subsequent entry of that series of items, and a switch of said setting means accessible from the exterior of the housing.

3. A combination switch, as claimed in claim 2, incorporating in the housing a compartment to receive one or more batteries for supply of the circuits.

4. A combination switch, as claimed in claim 1, wherein said keyboard is separate from said memory circuit and control switch and setting means.

5. A combination switch, as claimed in any one of claims 1 to 4, wherein said setting means includes a setting switch which is operable only by insertion and manipulation of a key.

6. A combination switch, as claimed by any one of claims 1 to 5, comprising a pair of alarm terminals incorporated in an alarm circuit connected to the memory circuit, the arrangement being such that entry into the memory circuit subsequently of any series of items other than that initially entered causes actuation of the alarm circuit to bridge the alarm terminals.

7. A combination switch substantially as described herein with reference to Figure 1 of the accompanying drawings.

8. An arrangement, for control of fuel feed of a motor driven vehicle, comprising a combination switch as claimed in any one of claims 1 to 7, and a shut-off valve disposed in a fuel-feed line, the shut-off valve being return loaded to closed state and being electrically openable against that return loading, the shut-off valve and the control switch being connected for operation of the shut-off valve by an electrical current source of the vehicle.

9. An arrangement, as claimed in claim 8, comprising a manual on-off switch controlling current feed to the shut-off valve, said on-off switch having a hold device adapted to hold it in current-feeding condition, and the control switch being connected for operation of the hold device.

10. An arrangement, for control of a braking system for a vehicle having a master cylinder, one or more slave cylinders, and a flow path for hydraulic fluid between the master cylinder and the or each slave cylinder, characterised in that said flow path has two branches in parallel, one said branch incorporating a non-return valve permitting flow of fluid only in the direction from the master cylinder towards the or each slave cylinder, and the other said branch incorporating a shut-off valve which is return loaded to closed state and is electrically openable against that return loading, said shut-off valve being connected in a current feed circuit with the control switch of a combination switch as claimed in any one of claims 1 to 7.

11. An arrangement for control of fuel feed of a motor driven vehicle substantially as described herein with reference to Figure 2 of the accompanying drawings.

12. An arrangement for control of a braking system for a vehicle substantially as described herein with reference to Figure 3 of the accompanying drawings.