US20030221578A1

US20030221578A1 - Detonator with onboard electronics mechanically connected to ignition element

Info

Publication number: US20030221578A1
Application number: US10/158,677
Authority: US
Inventors: David Forman; Abrar Tirmizi; Bruce Kwiatkowski; Thomas Cook
Original assignee: Special Devices Inc
Current assignee: Special Devices Inc
Priority date: 2002-05-29
Filing date: 2002-05-29
Publication date: 2003-12-04
Also published as: EP1509742A1; AU2003228015A1; WO2003100343A1; ZA200409577B

Abstract

A detonator with onboard electronics and an ignition element that are mechanically connected together.

Description

BACKGROUND OF THE INVENTION

The present invention relates to pyrotechnic detonators, and more particularly, to a detonator having onboard electronics and an ignition element that are mechanically connected to each other.

The efficient use of explosives in mining operations and the demolition of structures often requires that many charges be placed in a predetermined pattern and detonated in a timed sequence. In general, timed detonation can be accomplished by detonators that use pyrotechnic delays, sequential-type blasting machines, and electronically programmable detonators. Some examples of detonators that have onboard electronics, i.e., electronics contained within the detonator itself, for processing an ignition signal from, e.g., a blasting machine, are described in U.S. Pat. Nos. 6,173,651, 6,085,659, 6,079,332, 5,602,360, 5,460,093, 4,869,170, 4,819,560, 4,730,558, and 4,712,477, the disclosures of which are hereby incorporated by reference herein.

Such detonators involve soldered connections between the ignition element of the detonator to the onboard electronics, which presents at least the risk of damaging or detonating the ignition element. It is believed that hitherto this problem has not been addressed through the provision of a means to mechanically connect the ignition element to the onboard electronics in a detonator.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a means to mechanically connect the ignition element in a detonator to onboard electronics, thus eliminating the risk of making a soldered or similar connection in immediate proximity to the ignition element of the detonator.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a top sectional view of an embodiment of the present invention. [0005]
FIG. 2 is a partial top sectional view of the ignition element and connection portion of the embodiment shown in FIG. 1. [0006]
FIG. 3 is side view corresponding to FIG. 2. [0007]

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT¹

Referring to FIGS. [0008] 1-3, a detonator utilizing an embodiment of the present invention is shown. Referring to FIG. 1, an ignition subassembly 8 is placed inside of a shell 40 that may contain a primary charge 36 and a base charge 38 loaded into its closed end. (A detonator shell is typically a metal cylinder 6 to 8 mm. in diameter and from 60-100 mm. in length). Subassembly 8 can then be secured in place in the shell 40, such as by placing an elastomeric plug or the like (see elastomeric plug 46 and crimp 47 in FIGS. 5 and 6) in the open end of the shell and crimping the shell 40 to the plug, or other suitable method. Subassembly 8 may have a body portion formed of an encapsulation 31 and is preferably formed to snugly fit within the shell 40, preferably with features such as ridges or other protuberances formed to dampen vibrations to which the detonator may be subjected, generally in accordance with the teachings of U.S. Pat. No. 6,079,332. Some relevant teachings regarding encapsulation are also set forth in U.S. Pat. Nos. 6,079,332 and 4,869,170.
A header-based, or automotive airbag initiator-style, [0009] ignition element 28 is shown in the embodiment depicted in the Figures, but a detonator according to the present invention may include any kind of suitable ignition element (e.g., matchhead-type). U.S. Pat. Nos. 6,274,252, 5,709,724, 5,639,986, 5,602,359, 5,596,163, 5,404,263, 5,140,906, and 3,971,320 are also hereby incorporated by reference herein for their disclosure concerning the construction of ignition elements based on a glass-to-metal sealed header feedthrough, including the types of pins commonly used.
As shown in FIG. 2, [0010] ignition element 28 includes a header assembly with a sealed electrical feedthrough, comprising an eyelet 10 (preferably stainless steel), insulator glass 14 (preferably a glass such as a sodasilicate, e.g., 9010, that is chosen to form a compression seal with the eyelet and center pin, or less preferably a matched seal), a center pin 18 (preferably iron/nickel alloy), a ground pin 20, and an igniter wire 12 (preferably a low energy igniter wire with a diameter of 10 to 20 microns). The ignition element 28 further preferably includes a charge can 26 that is preferably metallic and hermetically sealed to the eyelet at circumferential through-weld 16, with an ignition charge 30 contained between the can 26 and upper surface of the header, in tight contact with igniter wire 12. An insulator cup 27 may preferably be attached around the can 26 so that, except for female connectors 52 that protrude from the input end of the subassembly, the entire outer surface of ignition subassembly 8 consists of insulating material, thus providing electrical isolation and vibration and environmental protection to the components within until such time as the subassembly is placed in the detonator shell.
Turning again to FIG. 1, it can be seen that a [0011] circuit board 24 and electronic components 25 are provided within ignition subassembly 8, to provide a means of triggering ignition of the ignition element based on the processing of an electrical ignition signal from a blasting machine or the like that supplies power and commands to the detonator. Such electronic components are well-known and preferably include means for imparting a programmable period of delay to the ignition, means for ESD and RF protection, et cetera. (Another preferred alternative is the use of an application-specific integrated circuit). Circuit board 24 and electronic components 25 are preferably encapsulated together in encapsulation 31, and connected to female connectors 52 and to plug and crimp connectors 50 at contacts 22 through soldering or other suitable connection.
Suitable plug and [0012] crimp connectors 50 that may be purchased off the shelf are suitable for use in an embodiment of the present invention like that depicted. Thus, after the plug and crimp connectors 50 are attached to the circuit board 24 (or other electronics), pins 18 and 20 of ignition subassembly 28 are inserted within the openings of connectors 50, and a crimping tool is used to securely crimp the connectors 50 to pins 18 and 20. Virtually any contact pin (of appropriate size) designed for use with a header is suitable for use with connectors 50. After the plug and crimp connection has been made, ignition subassembly 8 can be completed by the provision of encapsulation 31 around the circuit board, electronics, plug and crimp connectors, pins, and bottom of the ignition subassemblies.
Alternately to a plug and crimp connection, a standard off-the-shelf “Insulation Displacement Connection” (IDC) can be made, with or without insulation sheathing on the pins. IDCs may be soldered during circuit board assembly in conventional fashion. The [0013] pins 18 and 20 of ignition subassembly 28 can then be inserted into an IDC and secured.
It should be noted that although the Figures depict embodiments including electronic components that receive, process, and deliver an ignition signal, such an ignition signal may alternately be received, processed, and delivered by a number of other well-known non-electronic or partly-electronic means, such as through the use of a shock tube to deliver an ignition signal to a piezoelectric device, column fuse delays, et cetera. It is noted that this detailed description of certain embodiments herein does not imply that such alternate embodiments are not within the scope of the invention. [0014]
A preferred embodiment of a detonator having an ignition element and onboard electronics that are mechanically connected together, and many of its attendant advantages, has thus been disclosed. It will be apparent, however, that various changes may be made in the form, construction, and arrangement of the parts without departing from the spirit and scope of the invention, the form hereinbefore described being merely a preferred or exemplary embodiment thereof. Therefore, the invention is not to be restricted or limited except in accordance with the following claims. [0015]

Claims

What is claimed is:

1. An ignition subassembly for use in a detonator, comprising an ignition element and electronics for processing an ignition signal, said electronics being mechanically connected to said ignition element.

2. The ignition subassembly of claim 1, wherein the mechanical connection between said ignition element and said electronics includes a plug and crimp connection.

3. The ignition subassembly of claim 1, wherein the mechanical connection between said ignition element and said electronics includes an insulation displacement connection.

4. The ignition subassembly of claim 1, wherein said electronics include a circuit board having two ends, one of the ends of said circuit board being mechanically connected to said ignition element.

5. The ignition subassembly of claim 1, wherein said ignition element includes a glass-to-metal header having a sealed feedthrough.

6. The ignition subassembly of claim 2, further comprising two plug and crimp connectors, wherein said ignition element includes two electrode pins that mate with said plug and crimp connectors.

7. A detonator comprising:

a) an ignition element;

b) electronics for processing an ignition signal; and,

c) a mechanical connector assembly between said ignition element and said electronics, said connector mechanically connecting said ignition element to said electronics.

8. The detonator of claim 7, wherein said mechanical connector assembly includes a plug and crimp connector.

9. The detonator of claim 7, wherein said mechanical connector assembly includes an insulation displacement connector.

10. The detonator of claim 7, wherein said ignition element includes a glass-to-metal header having a sealed feedthrough.

11. The detonator of claim 7, wherein said electronics comprise a circuit board that includes electronic components for processing an ignition signal.

12. The detonator of claim 11, wherein said mechanical connector assembly is soldered to said circuit board at one or more through-board contacts.

13. A method of making an ignition subassembly for use in a detonator, comprising the following steps:

a) providing an ignition element suitable for initiating the detonator;

b) providing electronics for processing an ignition signal that is intended to trigger said ignition element;

c) providing a mechanical connector assembly comprising a male portion and a female portion;

d) incorporating or attaching said male portion of said connector assembly to one of said ignition element or said electronics;

e) incorporating or attaching said female portion of said connector assembly to the other of said ignition element and said electronics; and,

f) mechanically connecting together said male and female portions of said connector assembly.

14. The method of claim 13, wherein step c) includes the step of providing at least one plug and crimp connector.

15. The method of claim 13, wherein step c) includes the step of providing at least one insulation displacement connector.

16. The method of claim 13, wherein step a) includes the step of providing a glass-to-metal header having a sealed feedthrough, and wherein step d) includes the step of providing said header with a ground pin protruding away from said header, and the step of sealing a center pin in said header so as to form said sealed feedthrough and so as to protrude away from said header.

17. The method of claim 16, wherein step e) includes the step of attaching two plug and crimp connectors to said electronics, and wherein step f) comprises the step of pushing said pins into said plug and crimp connectors and crimping said plug and crimp connectors to said pins.

18. The method of claim 13, wherein step b) comprises the step of providing a circuit board including electronic components for processing an ignition signal.

19. The method of claim 18, wherein step e) comprises the step of soldering two plug and crimp connectors to said circuit board at through-board contacts.

20. The method of claim 17, further comprising the step of substantially encapsulating said electronics, plug and crimp connectors, and pins.