GB2169994A

GB2169994A - Systems for activating a firing device on board a weapon

Info

Publication number: GB2169994A
Application number: GB08501685A
Authority: GB
Inventors: Ronald David Sexton
Original assignee: British Aerospace PLC
Current assignee: BAE Systems PLC
Priority date: 1985-01-23
Filing date: 1985-01-23
Publication date: 1986-07-23
Also published as: GB2169994B

Abstract

A safety and arming systems for detonating a missile warhead or igniting a missile boost motor, in which faults do not initiate premature arming, initiates firing on the attainment of a set of predetermined operating conditions. A transformer 1 is connected to an electronic switch 7,8 on the primary side 5 and to a detonator 3 on the secondary side 6, the switch having a plurality of control inputs 10-12 for receiving signals indicative of the attainment of each of the operating conditions. Once the operating conditions have been attained, a dc supply to the primary coil is chopped according to pulses received at 9 from a clock pulse generator to generate an ac supply in secondary coil 6. <IMAGE>

Description

SPECIFICATION Systems for activating a firing device on board a weapon This invention relates to a system for activating a firing device on board a weapon such as a missile.

Many safety and arming systems now used on board missiles operate on the closure of a series of mechanical switches, each switch closing when a predetermined parameter relating to that switch is attained eg a given acceleration or spin. These systems allow the missile to be handled and launched in comparative safety and the switches are closed during missile flight once their related parameters have been attained, until the missile is fully armed.

However, the current designs of such systems are tending towards a combination of electronic and mechanical techniques, which may suffer from the effects of electromagnetic interference and the like.

It is therefore desirable to implement a system in which faults occurring before the required instant do not initiate premature arming of the missile.

According to one aspect of the present invention, there is provided a weapon including an electrically-energised firing device and electrical activation means for activating the device when a predetermined set of operating conditions have been attained, the activation means comprising: dc energy supply means; pulse signal supply means; control means for supplying respective signals indicative of the attainment of said operating conditions; electronic switch means having a plurality of switch control inputs, one of said inputs being connected to said pulse signal supply means for receiving pulse signals supplied therefrom, and further ones of said inputs are connected to said control means for receiving respective signals indicative of said operating conditions; and transformer means having a primary and a secondary side, the primary side being connected to said dc energy supply means via said switch means and the secondary side being connected to the firing device; whereby on the attainment of said operating conditions, said switch means is operable to pass pulses of energy from said supply means to the primary side of the transformer means.

For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawing, the single Figure of which is a circuit diagram of an ac coupled arming and detonation system for a missile.

The circuit shown has a ferrite-cored transformer 1 which couples energy from a dc supply 2 on its primary side with a detonator 3 on its secondary side. The transformer 1 has an integral screen 4 positioned between the primary coil 5 and secondary coil 6, which is maintained at a potential of OV and provides additional isolation between the primary and secondary coils. The primary coil 5 of the transformer is supplied by a dc supply 2 via two MOSFET transistors 7 and 8, each transistor having two insulated gates, which allows the system to use four input lines 9, 10, 11 and 12, each line corresponding to an insulated gate. One of the gates, 9, is connected to a clock pulse generator (not shown) which provides pulse signals to 'chop' the steady supply from the dc supply 2.The other gates 10, 11 and 12 are connected to the missile computer (not shown) and each gate operates when a dc signal corresponding to the attainment of the flight parameter associated with that gate has been received. Once gates 10, 11 and 12 are closed ie the dc supply 2 is connected to the primary coil 5, the supply is 'chopped' according to the pulse signals being received at gate 9. This generates an ac supply in the secondary coil 6 of the transformer. This ac supply is then used to activate the detonator 3.

The circuit described and shown in the drawing may be designed to be relatively immune to the effects of electromagnetic interference and the like, and to allow multiple 'failures' to occur with the system remaining 'safe'.

The secondary side of the transformer may further include an isolating capacitor and the firing device is coupled to the circuit via the capacitor.

The pulse signals used to 'chop' the steady dc supply may be derived from the clock pulse generator of the missile computer.

Instead of being used for arming and detonating the missile warhead, the system shown may be used for igniting a missile motor, for example a secondary stage boost motor.

The supply from the dc supply 2 may be at any convenient voltage and is normally derived from the thermal batteries present on board a missile.

The turns ratio of the transformer 1 is chosen to match the system in which the transformer is to be used.

Instead of two twin gate MOSFET transistors, an appropriate number of single gate transistors can be used, or a combination of transistors having different numbers of gates.

For example, where only two operating parameters have to be checked instead of three as shown, one of the twin gate transistors 7 and 8 could be replaced by a single gate transistor.

1. A weapon including an electrically-energised firing device and electrical activation means for activating the device when a predetermined set of operating conditions have been attained, the activation means comprising: dc energy supply means; pulse signal supply means; control means for supplying respective signals indicative of the attainment of said operating conditions; electronic switch means having a plurality of switch control inputs, one of said inputs being connected to said pulse signal supply means for receiving pulse signals supplied therefrom, and further ones of said inputs are connected to said control means for receiving respective signals in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Systems for activating a firing device on board a weapon This invention relates to a system for activating a firing device on board a weapon such as a missile. Many safety and arming systems now used on board missiles operate on the closure of a series of mechanical switches, each switch closing when a predetermined parameter relating to that switch is attained eg a given acceleration or spin. These systems allow the missile to be handled and launched in comparative safety and the switches are closed during missile flight once their related parameters have been attained, until the missile is fully armed. However, the current designs of such systems are tending towards a combination of electronic and mechanical techniques, which may suffer from the effects of electromagnetic interference and the like. It is therefore desirable to implement a system in which faults occurring before the required instant do not initiate premature arming of the missile. According to one aspect of the present invention, there is provided a weapon including an electrically-energised firing device and electrical activation means for activating the device when a predetermined set of operating conditions have been attained, the activation means comprising: dc energy supply means; pulse signal supply means; control means for supplying respective signals indicative of the attainment of said operating conditions; electronic switch means having a plurality of switch control inputs, one of said inputs being connected to said pulse signal supply means for receiving pulse signals supplied therefrom, and further ones of said inputs are connected to said control means for receiving respective signals indicative of said operating conditions; and transformer means having a primary and a secondary side, the primary side being connected to said dc energy supply means via said switch means and the secondary side being connected to the firing device; whereby on the attainment of said operating conditions, said switch means is operable to pass pulses of energy from said supply means to the primary side of the transformer means. For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawing, the single Figure of which is a circuit diagram of an ac coupled arming and detonation system for a missile. The circuit shown has a ferrite-cored transformer 1 which couples energy from a dc supply 2 on its primary side with a detonator 3 on its secondary side. The transformer 1 has an integral screen 4 positioned between the primary coil 5 and secondary coil 6, which is maintained at a potential of OV and provides additional isolation between the primary and secondary coils. The primary coil 5 of the transformer is supplied by a dc supply 2 via two MOSFET transistors 7 and 8, each transistor having two insulated gates, which allows the system to use four input lines 9, 10, 11 and 12, each line corresponding to an insulated gate. One of the gates, 9, is connected to a clock pulse generator (not shown) which provides pulse signals to 'chop' the steady supply from the dc supply 2.The other gates 10, 11 and 12 are connected to the missile computer (not shown) and each gate operates when a dc signal corresponding to the attainment of the flight parameter associated with that gate has been received. Once gates 10, 11 and 12 are closed ie the dc supply 2 is connected to the primary coil 5, the supply is 'chopped' according to the pulse signals being received at gate 9. This generates an ac supply in the secondary coil 6 of the transformer. This ac supply is then used to activate the detonator 3. The circuit described and shown in the drawing may be designed to be relatively immune to the effects of electromagnetic interference and the like, and to allow multiple 'failures' to occur with the system remaining 'safe'. The secondary side of the transformer may further include an isolating capacitor and the firing device is coupled to the circuit via the capacitor. The pulse signals used to 'chop' the steady dc supply may be derived from the clock pulse generator of the missile computer. Instead of being used for arming and detonating the missile warhead, the system shown may be used for igniting a missile motor, for example a secondary stage boost motor. The supply from the dc supply 2 may be at any convenient voltage and is normally derived from the thermal batteries present on board a missile. The turns ratio of the transformer 1 is chosen to match the system in which the transformer is to be used. Instead of two twin gate MOSFET transistors, an appropriate number of single gate transistors can be used, or a combination of transistors having different numbers of gates. For example, where only two operating parameters have to be checked instead of three as shown, one of the twin gate transistors 7 and 8 could be replaced by a single gate transistor. CLAIMS

1. A weapon including an electrically-energised firing device and electrical activation means for activating the device when a predetermined set of operating conditions have been attained, the activation means comprising: dc energy supply means; pulse signal supply means; control means for supplying respective signals indicative of the attainment of said operating conditions; electronic switch means having a plurality of switch control inputs, one of said inputs being connected to said pulse signal supply means for receiving pulse signals supplied therefrom, and further ones of said inputs are connected to said control means for receiving respective signals in dicative of said operating conditions; and transformer means having a primary and a secondary side, the primary side being connected to said dc energy supply means via said switch means and the secondary side being connected to the firing device; whereby on the attainment of said operating conditions, said switch means is operable to pass pulses of energy from said supply means to the primary side of the transformer means.

2. A weapon according to claim 1, wherein the dc energy supply means comprises a thermal batter.

3. A weapon according to claim 1 or 2, wherein the electronic switch means comprises a plurality of insulated gate MOSFET transistors, each having its source/drain path connected in series with said dc energy supply and the primary side of said transformer and each having one or more control gate inputs, the control gate inputs of the plurality of transistors being connected to said control means and said pulse signal supply means.

4. A weapon according to claim 1, 2 or 3, wherein the control means is a missile computer.

5. A weapon according to any preceding claim, wherein the pulse signal supply means comprises a clock pulse generator forming part of a missile computer.

6. A weapon according to any preceding claim, wherein the transformer means comprises a ferrite-cored transformer.

7. A weapon according to claim 6, wherein the transformer includes an isolating screen between the primary and secondary sides.

8. A weapon according to any preceding claim, wherein the firing device is coupled to the secondary side of the transformer via an isolating capacitor.

9. A missile including an explosive warhead, a firing device for detonating the warhead, and electrical arming means for arming the firing device when a predetermined set of operating conditions have been attained, the arming means comprising: dc energy supply means; pulse signal supply means; control means for supplying respective signals indicative of the attainment of said operating conditions; electronic switch means having a plurality of switch control inputs, one of said inputs being connected to said pulse signal supply means for receiving pulse signals supplied therefrom, and further ones of said inputs are connected to said control means for receiving respective signals indicative of said operating conditions; and transformer means having a primary and a secondary side, the primary side being connected to said dc energy supply means via said switch means and the secondary side being connected to the firing device; whereby on the attainment of said operating conditions, said switch means is operable to pass pulses of energy from said supply means to the primary side of the transformer means.

10. A missile including a motor, an ignition device for igniting the motor, and electrical operation initiating means for initiating operation of the ignition device when a predetermined set of operating conditions have been attained, the operation initiating means comprising: dc energy supply means; pulse signal supply means; control means for supplying respective signals indicative of the attainment of said operating conditions; electronic switch means having a plurality of switch control inputs, one of said inputs being connected to said pulse signal supply means for receiving pulse signals supplied therefrom, and further ones of said inputs are connected to said control means for receiving respective signals indicative of said operating conditions; and transformer means having a primary and a secondary side, the primary side being connected to said dc energy supply means via said switch means and the secondary side being connected to the motor; whereby on the attainment of aid operating conditions, said switch means is operable to pass pulses of energy from said supply means to the primary side of the transformer means.

11. A weapon substantially as hereinbefore described with reference to the accompanying drawing.