IL41575A - Igniters for mines actuated by air pressure - Google Patents

Abstract

1359976 Mine detonating devices TECHNICAL ARCO ESTABLISHMENT 23 Feb 1973 [16 March 1972] 8908/73 Heading F3A A mine detonating device resistant to actuation by surges of pressure caused by nearby explosions comprises a striker 3 which is released when air in a chamber 8 is forced through a nozzle 11 into a chamber 7 by the depression of a cap 9. Sudden and unusually high increases in air pressure acting on the cap as a result of nearby explosions however causes the cap to seat on the nozzle 11 and prevents communication between the chambers. A flexible member 6 carries a striker locking member 5. For consistency in response, even under rapid temperature variations, a chamber containing the striker communicates with a chamber 15 defined on one side by a resilient membrane 14 exposed to ambient pressure. [GB1359976A]

Description

Igniters mines actuated air pressure AfiCO ESTABLISHMENT 39735 This invention relates to mine detonating particularly mines which are located in the ground or are dropped by patent specification describes an antimagnetic mine comprising a safety device which acts to compensate for pressure changes caused by temperature For this purpose a very small air passage cosmunicating between an air chamber inside the mine and the outside of the mine is This arrangement allows air to escape into the in case of a temperature and air to enter the in case of a decrease in this arrangement may draw damp air into the which may result in damages to the According to the present invention there is provided a mine detonating device comprising a firing pin actuatable in response to an increase in pressure in a second chamber which communicates with a chamber in which pressure is increased in response to external conditions by means of a cap having a movable surface which defines at least a part of the first the communication between the chambers including a nozzle which extends into the first chamber and is positioned so that when a sudden and unusually high increase in air pressure acts on the cap the movable surface thereof seats on the nozzle and prevents communication between the first and second chambers so that the pressure increase is not applied to the second In a preferred device according to the invention the outer wall of the mine body includes one or more each having therein a resilient membrane which a chamber in the the chamber being in communication with an inner chamber of the mine in which the firing pin so as to change the pressure therein in response to changes the such as a rapid temperature The s detonating device according to the invention is less susceptible than prior devices to actuation by variations in pressure such as may be caused by an explosion in the vicinity of the In addition the preferred is also less susceptible to temperature variations which prior art devices tend to vary the conditions required to cause actuation of the mine detonating A preferred embodiment of the invention is inafter particularly described with reference to the panying drawings which is a cross section of an mine which is rot sensitive to the pressure surges which are brought about by nearb The mine comprises a body a detonator a firing pin biassed by a spring 4 and slidably mounted inside a hollow cylinder which in turn is kept in situ by means of a resilient membrane which defines the bottom side of the air chamber The top of the chamber 7 is defined by a member of the mine body and above this there is another air chamber which is defined at the top by the cap of the mine connected to the body of the in a resiliently movable Both the air chambers 7 and 8 are connected by means of a short and narrow conduit 10 which extends in the chamber through a nozzle The mine functions as When a pressure of a certain value is applied to the cap this latter goes wardly compressing the air in chamber 8 which through the conduit will increase the pressure in chamber when the of Such pressure increase in the chamber 7 snaps off the r and detonates the However when the pressure exerted on the cap is a temporary one for by a nearby the air which enters the chamber through the conduit is not sufficient to bring the pressure inside the latter chamber to the value which is needed to actuate the firing pin and when the temporary in c rease is over the air in the chambers 7 and 8 revert to the original Its is for a very powerful explosion in the vicinity of the mine to cause the compression of the air in the chamber 8 to take place sufficiently quickly and with sufficient pressure increase to cause the mine to be In order to prevent such a hazard the nozzle of the conduit protrudes into said chamber so that when a very strong and sudden blast takes place the cap because of the strong pressure said air pressure surge exerts on is deflected until it bears on the nozzle thus closing the conduit 10 and preventing the air at high pressure in the chamber 8 f om entering into the chamber Thus the explosion of the mine is After the usually a very short one in of the air pressure surge the cap goes back into its normal position and the mine is again ready for The body 1 of the mine is formed also with one or more recesses one such recess is shown in the The recess is closed by a plate 13 and inside the recess is a thin resilient membrane 14 which defines a chamber between it and the the chamber being in communication with a chamber which surrounds the firing If the mine is subjected to a temperature substantially different from that at which it was the pressure of the air contained in the inner Chambers of the and thus the mine functions at pressures different from the predetermined pressures at normal This effect is reduced by the fact that an increased pressure is also developed in the chambers 15 and since these communicate with the chamber which surrounds the firing pin device a similar pressure increase occurs in the region of the firing This increase of pressure tends to compensate for the pressure changes in the chambers 7 and insufficientOCRQuality

Claims (4)

1. A mine detonating device comprising a firing pin actuable in response to an increase in pressure in a second chamber which communicates with a first chamber in which the pressure is increased in response to external conditions by means of a cap having a movable surface which defines at least a part of the first chamber, the communication between the chambers including a nozzle which extends into the first chamber and is positioned so that when a sudden and unusually high increase in air pressure acts on the cap the movable surface thereof seats on the nozzle and prevents communication between the first and second chambers so that the pressure increase is not applied to the second chamber.

2. A device according to Claim 1 in which the surface of the cap is movable by virtue of the inherent resilience of the cap.

3. A device according to Claim 1 or 2 in which the outer wall of the mine body includes one or more recesses, each having therein a resilient membrane which defines a chamber in the recess, the chamber being in communication with an inner chamber of the mine in which the firing pin is located so as to change the pressure therein in response to changes in the mine's environment such as a rapid temperature variation.

4. * A mine detonating device substantially as herein as described with reference to aad/shown in the accompanying drawings. For the Applicants DR. REINHOLD COHN AND PARTNERS By: HE:mr