A three-way blast signal transmission device

Abstract

A three-way blast signal transmission device 10 for use between an initiator 12 and two shock devices 14 includes: a two-way splitter 18 formed in or supported on a body 20. The two-way splitter 18 co

Description

Field The present invention relates to a three-way blast signal transmission device, such as the type used in remote detonation systems. Background In specialist marine salvage applications for example, and when there is a need to destroy unexploded ordinance or obstructions, especially at sea, there is often a need for multiple charges to be detonated in order to destroy or render explosives harmless. These systems usually require a detonator to be initiated by personnel at a distance which may be several hundred metres from a charge. Prior Art European patent application EP 0 385 614 (ICI PLC) discloses a connection device for a blasting signal transmission tube. The device has a housing consisting of hinged sections which have arcuate raised parts and grooves which together define two arcuate channels. These channels are in turn connected to a further channel. In use, first and second lengths of transmission tube are located in the arcuate channels and are partially cut to form apertures so that a blasting signal entering the connector, via one of the tubes, emerges from the tube, traverses a connecting channel and initiate a signal in each arm of the other tubes. The aforementioned connection device for a blasting signal transmission tube is complex and expensive. There is therefore a need for a simpler device which is robust, reliable and cheaper to make. There is also a need for a connection device for a blasting signal transmission tube which may be used to detonate multiple charges simultaneously and in a reliable manner. The present invention arose in order to overcome the aforementioned problem and seeks to provide a simpler connection device for a blasting signal transmission tube which splits a blast signal into at least two secondary tubes. Summary of the Invention According to a first aspect of the invention there is provided a three-way blast signal transmission device for use between an initiator and two shock devices includes: a two-way splitter formed in, or supported on a body, the two-way splitter connects the transmission tube from the initiator to a second transmission tube and a third transmission tube thereby splitting a signal from the initiator and transmitting separate signals via the second and third transmission tubes to each of two shock devices. In some embodiments the two-way splitter includes a chamber to which is connected the transmission tube from the initiator and the second and third transmission tubes. Optionally further transmission tubes may be used. In some embodiments the chamber is formed within the body of the device. In some embodiments the chamber is formed by the intersection of three holes, one input hole is for the initiator tube and the other two output holes each lead to separate shock devices. The axes of the holes are at a maximum of 120° one to another. Preferably the three holes are drilled holes into a solid body of the device. It has been noted that as the angle between respective input holes and each of the two output holes increases to 180°, the efficiency of transmission of signals becomes lower and less reliable. Thus, an angular spacing of 120° between each hole, ensures consistent and efficient coupling of the input signal to the two output tubes. However, the angle between the two output tubes may be less than 120°. In some embodiments the input and output holes each receive a flexible sleeve therein. In some embodiments the three flexible synthetic plastics sleeves are cemented, glued or bonded within each of the three respective holes. In some embodiments three flexible synthetic plastics sleeves are formed from polyvinyl chloride (PVC) material. Advantageously the three tubes to create a chamber which allows the signal to be coupled efficiently and evenly. The connection device for a blasting signal transmission tube therefore enables multiple charges or disruptors to be deployed safely and at distance to an initiator. An example of the invention will now be described, with reference to the drawings, in which: Brief Description of the Drawings Figure 1 shows an overall view of one embodiment of a three-way blast signal transmission device; Figure 2 shows a detailed plan view of the embodiment shown in Figure 2; and Figure 3 shows an overall diagrammatical view of a system which includes the three-way blast signal transmission device. Detailed Description of Preferred Embodiments of the Invention Referring to Figures 1 and 2 there is shown an example of a three-way blast signal transmission device 10 for use between an initiator 12 and two shock devices 14 and 16 shown diagrammatically in Figure 3. The transmission device 10 has a two-way splitter 18 formed in its body 20. The two-way splitter 18 connects transmission tube 22 from the initiator 12 to a second transmission tube 26A and a third transmission tube 28B thereby splitting a signal from the initiator 12 and transmitting separate signals via the second 26 and third 28 transmission tubes, via transmission lines 26A and 28A to each of the two shock devices 14 and 16 respectively. The two-way splitter 18 in the body 20 of the signal transmission device 10 has a chamber 32 to which is connected the transmission tube 22 from the initiator 12 and the second transmission tube 25A and third transmission tube 27A. Chamber 50 is formed within the body of the device at the intersection of two output tubes 26A and 28A and input tube 22. Chamber 50 is defined by a triangular cavity at the intersection of three holes whose axes of symmetry are at 120° one to another. This is important because, in combination with a 2 mm diameter bore tube, the arrangement ensures that the shock signal is successfully transmitted from the input tube to the two output shock tubes. The 2 mm diameter is larger than the ID of the shock tube. However, it will be appreciated that the cavity may be formed different bore diameters which receive different size shock tubes. The body 20 is formed form a synthetic plastics material such as nylon, acrylonitrile butadiene styrene (ABS), polyethylene or polypropylene. In the example shown in Figure 1, three mounting holes 40A, 40B and 40C are drilled through the body 20 of the device 10. These are for attaching the device 10 to an item, for example with tacks, screws or nails (not shown) or with plastic cable ties (not shown). In addition to these holes other holes 21,25 and 27 are formed or drilled into the body and each hole receives a flexible sleeve therein. The sleeves 21 A, 25A and 27A may be formed from polyvinylchloride (PVC) so that each is watertight. The three flexible synthetic plastics sleeves 21 A, 25A and 27A are cemented within each of the three respective holes 21,25 and 27 and transmission tubes 22, 26Aand 28Aare connected into them for example by crimping. The three transmission tubes 22, 26A and 28A are spaced around a triangle which defines sides of the chamber 50. In this manner three bores meet to create a common volume or cavity which acts to split the shock signal evenly into each output tube. Each of the three transmission tubes 22, 26A and 28A have a diameter of 2 mm bore and typically each is at least 25 metres, preferably at least 50 metres long. In some embodiments a tube or lead line (to the initiator) may be 50 metres to 100 metres in length. The two output tubes however are only 200 mm to 400 mm in length. If a sacrificial radio frequency (RF) imitator system is used, a lead input line may be 100 mm long. For example, if the three-way blast signal transmission device is held on a water surface or on a float, then the two disrupter or output tubes could be 5 metres long if attached to say an ordinance surface, such as a mine (not shown). A system includes: an initiator 12, the signal transmission device 10 first and second explosive devices 14 and 16 for simultaneous initiation. The invention has been described by way of example only and it will be appreciated that variation may be made to the embodiments described, without departure from the scope of the invention, as defined in the claims.

Claims

1. A three-way blast signal transmission device for use between an initiator and two shock devices includes: a two-way splitter formed in, or supported on a body, the two-way splitter connects the transmission tube from the initiator to a second transmission tube and a third transmission tube thereby splitting a signal from the initiator and transmitting separate signals via the second and third transmission tubes to each of two shock devices.

2. A signal transmission device according to claim 1 wherein the two-way splitter includes a chamber to which is connected the transmission tube from the initiator and the second and third transmission tubes.

3. A signal transmission device according to claim 2 wherein the chamber is formed within the body of the device.

4. A signal transmission device according to claim 3 wherein the chamber is formed by the intersection of three holes whose axes of symmetry are at 120° one to another.

5. A signal transmission device according to claim 4 wherein the three holes are drilled holes.

6. A signal transmission device according to either claim 4 or 5 wherein the holes each receive a flexible PVC sleeve therein.

7. A signal transmission device according to claim 6 wherein three flexible synthetic plastics sleeves are cemented within each of the three respective holes.

8. A signal transmission device according to claim 7 wherein three flexible synthetic plastics sleeves are formed from polyvinyl chloride (PVC) material.

9. A signal transmission device according to any of claims 2 to 8 wherein the three transmission tubes are spaced around a triangle which defines sides of the chamber.

10. A signal transmission device according to any preceding claim wherein the three transmission tubes have a diameter of 2mm bore.

11. A signal transmission device according to claim wherein at least the second and third transmission tubes are in excess of 50 metres long.

12. A signal transmission device according to any preceding claim wherein the body is formed from a synthetic plastics material, such as nylon.

13. A signal transmission device according to any preceding claim wherein the body has mounting holes formed therein.

14. A system includes: an initiator, the signal transmission device according to any preceding claim and at least two devices for simultaneous initiation.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS17 12248Claims1. A three-way blast signal transmission device for use between an initiator and two shock devices includes: a two-way splitter formed in, or supported on a body, the two-way splitter connects the transmission tube from the initiator to a second transmission tube and a third transmission tube thereby splitting a signal from the initiator and transmitting separate signals via the second and third transmission tubes to each of two shock devices, wherein the two-way splitter includes a chamber to which is connected the transmission tube from the initiator and the second and third transmission tubes and wherein the three transmission tubes are spaced around a triangle which defines sides of the chamber.

2. A signal transmission device according to claim 1 wherein the chamber is formed within the body of the device.

3. A signal transmission device according to claim 2 wherein the chamber is formed by the intersection of three holes whose axes of symmetry are at 120° one to another.

4. A signal transmission device according to either claim 3 wherein the holes each receive a flexible PVC sleeve therein.

5. A signal transmission device according to claim 4 wherein three flexible synthetic plastics sleeves are cemented within each of the three respective holes.

6. A signal transmission device according to claim 5 wherein three flexible synthetic plastics sleeves are formed from polyvinyl chloride (PVC) material.

97. A signal transmission device according to any preceding claim wherein the three transmission tubes have a diameter of 2mm bore.

8. A signal transmission device according to claim wherein at least the second and third transmission tubes are in excess of 50 metres long.

9. A signal transmission device according to any preceding claim wherein the body is formed from a synthetic plastics material.

10. A signal transmission device according to any preceding claim wherein the bodyhas mounting holes formed therein.

11. A system includes: an initiator, the signal transmission device according to any preceding claim and at least two devices for simultaneous initiation.10

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