GB2079904A - Signalling device - Google Patents

Abstract

An explosive signalling device intended to be thrown into the sea comprises a housing (10), a body (13) which comprises a base (14) and a plurality of elongated hollow formations (15-18) extending from the base, an explosive charge, a detonator for the charge, a power source and a switch for controlling energisation of the detonator. At least the power source and the switch are mounted in respective ones of the formation of the body and these formations are engaged at a position remote from the base of the body by a support (23) which is a sliding fit within the housing and prevents damage to the device when thrown from heights exceeding 100 m. Limited axial displacement of the support can occur on impact through the provision of spacer sleeves (24, 25) and foam discs (20, 21). <IMAGE>

Description

SPECIFICATION Signalling device This invention relates to an explosive device of the kind, hereinafter called the kind specified, comprising a body, an explosive charge, a detonator for the charge, a power source, at least one switch for controlling energisation of the detonator from the power source and a housing, wherein the body comprises a base and a plurality of elongated hollow formations extending from the base, the power source and the switch are mounted in respective ones of said formations and the body is contained in the housing.

Devices of the kind specified are used in signalling to submarines. Devices used for this purpose generally also include a pressureoperated switch which prevents energisation of the detonator until the device has sunk to a predetermined depth in the water.

It has been found that a device of the kind specified which is satisfactory when thrown into the sea from a ship is not entirely satisfactory when it enters the sea with a higher velocity, for example when thrown from a helicopter flying at a height exceeding 100 m. Occasionally, the impact with the surface of the sea of a device thrown from a height exceeding 100 m causes damage to the device which prevents explosion of the charge at the required depth.

According to a first aspect of the invention, there is provided a device of the kind specified having an elongated housing and a support disposed within the housing, the support engaging the housing at a position spaced from end portions of the housing.

The base of the body may engage and support internally one end portion of the housing and an opposite end portion of the housing may be engaged by a weight also contained in the housing.

The housing of a device in accordance with the first aspect of the invention may be identical with the housing of a device of the kind specified in use at the present time. Thus, a device in accordance with the first aspect of the invention can be stored in means provided for storing devices in use at the present time.

We also provide according to a second aspect of the invention a device of the kind specified comprising a support engaged with said formations at a position remote from the base of the body.

The support of a device in accordance with the second aspect of the invention is preferably engaged additionally with the housing to support same internally.

The support is preferably of plate-like form, having a peripheral size and shape such that it is a sliding fit within the housing and having apertures in which respective ones of the formations of the body are received with a sliding fit.

For restricting movement of the support along the housing, there may be provided spacers, one spacer being engaged between the support and the base of the body and the other spacer being engaged between the support and a weight or other element occupying an end portion of the housing remote from the base of the body.

The means for restraining longitudinal movement of the support preferably is or includes one or more resiliently deformable elements.

An example of the device embodying both aspects of the invention will now be described, with reference to the accompanying drawing, which shows a perspective view of a signalling device, a housing of the device being partly broken away to reveal internal components of the device.

The device comprises a cylindrical housing 10 formed of sheet metal and having in one end wall 11 an opening 12 which is normally closed by a removable closure (not shown).

Within the housing, there is disposed a body 13 having a circular base 14 which is received in a first end portion of the housing and is a sliding fit therein. The body further includes a number of hollow formations, 1 5, 16, 1 7 and 18, which extend from the body in a direction towards an opposite end portion of the housing. Each of these formations is substantially cylindrical and arranyed with its longitudinal axis parallel to a longitudinal axis of the housing. The base 14 and at least some of the formations 1 5, 16, 17 and 1 8 are integral with one another and are formed by moulding a plastics material.

The formation 1 6 contains an explosive charge and an electrically energisable detonator. The formation 1 8 contains an electrical power source.

The formation 1 7 contains a normally open switch which closes when subjected to salt water and the formation 1 5 contains a reed switch and magnet for maintaining the reed switch closed. The reed switch and magnet may be arranged in the manner described in British Patent Specification No. 1,246,831. The device also includes a pressure-operated switch (not shown) connected in series with the detonator, the power source, the reed switch and the switch contained in the formation 1 7 so that the charge will be exploded when the device sinks in water to a predetermined depth. In use of the device, water can enter the housing through the opening 12.If the charge is not exploded after the device has been in water for a predetermined period, the magnet contained in the formation 1 5 moves to open the reed switch and thereby render the device safe.

In an end portion of the housing 10 remote from the base 1 4 of the body, there is disposed a weight 1 9 trapped between foam discs 20 and 21. A disc 22 of plastics material lies between the foam disc 21 and the formation 16.

It has been found that devices as thus far described occasionally fail when thrown onto the surface of the sea from a height exceeding 100 metre. The impact with the surface of the sea sometimes causes severe deformation of the housing 10 and fracture of the body 13, particularly of the formations 1 5, 17 and 1 8 adjacent to the base 1 4. We have found that such failure of these devices can be eliminated by the provision of a support 23 and of spacers 24 and 25. The support 23 is of disc-like form and preferably has a thickness of approximately 10 millimetre, in a case where the internal diameter of the housing 10 is within the range 60 millimetre to 70 millimetre.The support is a sliding fit in the housing 10 and engages the internal surface of the housing at a position between the end portions thereof, preferably at a position which is approximately midway between the end walls of the housing. Thus, the support 23 provides internal support for the housing at a position between the base 14 of the body and the weight 19.

In the support 23 there is formed a number of circular openings and the formations 1 5, 1 6, 17 and 1 8 are received in respective ones of these openings with a sliding fit. The support embraces these formations near to their free ends. The formations are thereby supported against deflection of their free ends relative to the base 14.

The spacer 24 is interposed between the base 14 and the support 23 to limit approach of the support towards the base. The spacer 25 is interposed between the foam disc 21 and the support 23 to limit movement of the support away from the base 14. The spacers 24 and 25 consist of sleeves formed of polypropylene. Owing to the inherent resilience of these sleeves and of the foam discs 20 and 21, limited axial displacement of the support 23 can occur when the device is subjected to impact.

Claims (12)

1. A device of the kind specified having an elongated housing and a support disposed within the housing, the support engaging the housing at a position spaced from end Dortions of the housing.

2. A device of the kind specified comprising a support engaged with said formations of the body at a position remote from the base of the body.

3. A device according to Claim 2 wherein the support is engaged additionally with the housing.

4. A device according to any preceding Claim wherein the support is of plate-like form, having a peripheral size and shape such that it is a sliding fit within the housing and having apertures in which respective ones of the formations are received with a sliding fit.

5. A device according to Claim 4 wherein a spacer is interposed between the base of the body and the support.

6. A device according to Claim 5 wherein said spacer has the form of a sleeve and is formed of a resilient plastics material.

7. A device according to Claim 5 or Claim 6 comprising a further spacer interposed between the support and elements disposed in an end portion of the housing remote from the base of the body.

8. A device according to Claim 7 wherein said further spacer and/or one or more of said elements is resiliently deformable.

9. A device according to any one of Claims 5 to 8 wherein there is a clearance space between said formations and the or each spacer.

10. A device according to any preceding claim wherein said support engages at least one of said formations at a position adjacent to a free end of the formation remote from the base of the body.

11. A device substantially as herein described with reference to and as shown in the accompanying drawing.

12. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.