Ammunition and explosives – Igniting devices and systems – Electrical primer or ignitor
Reexamination Certificate
2001-11-27
2003-12-02
Nelson, Peter A. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Electrical primer or ignitor
C102S202900, C102S202110, C102S202140, C102S275120
Reexamination Certificate
active
06655289
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a trigger unit for initiating pyrotechnic elements.
By pyrotechnic elements are to be understood all elements which, as a result of the application of a electric voltage, preferably in correction with coded signals, trigger a pyrotechnic effect that has a desired result, for example the ignition of an explosive charge or the triggering of the gas generator of an air bag or belt tightener. Thus, inter alia fuses, in particular detonating fuses for civil and high-security domains (automotive, military and oil-field domains), ignition elements and gas generators belong to the pyrotechnic elements.
Electronic fuses whose ignition lines have commercially available plugs, for example DIN plugs, jack plugs, RCA plugs or BNC plugs, with which the electrical connection to the terminal lines of other fuses and the detonating machine is established, are known from EP 0 849 562 A2. These known electronic fuses each have an ignition line of a specific length which end initially in, for example, a jack plug. Emerging from this plug there is a further line (bus line) which ends in a plug socket that is compatible with the jack plug. The plug and plug socket of a fuse are wired in such a way that the individual poles are short-circuited when the former are plugged together. The fuses are delivered with plugs plugged into the socket. This is to provide protection against unintentional ignition, in particular in the case of an external voltage effect and high-frequency loading Before the fuse is assembled, the ignition line with the plugs connected thereto must be soldered onto the electronic circuit of the fuse.
Electric fuses in which the wires of the ignition line are embedded, in a twisted state, in the stopper sealing the housing of the fuse are known from DE-OS 28 24 568. A specific length of the ignition line is assigned to the fuse. If required, the components of a plug connection can be connected to this ignition line. Fuses equipped in such a way have the disadvantage that the ignition line attached thereto takes up more space and is heavier than the fuse itself.
Moreover, an ignition line that is already connected to the ignition means, for example an ignition cap, or to the hybrid containing the electronic components complicates the assembly of the fuses Before assembly of the known fuses, the ignition line must be soldered or welded onto the hybrid or the ignition cap. The ignition line that is coiled and which is substantially large in terms of volume and mass, hangs from these small dimensioned parts, on the flexurally slack wires, whereby manual assembly of the components of the fuses is complicated and mechanical assembly becomes expensive and has long cycle times.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to purpose a trigger unit for initiating pyrotechnic elements that can be produced in a rational manner.
The object is achieved by surrounding the switch and the control unit by a first housing case, the first housing case being connected to a second housing case which contains the charge body, and by having the ignition means go right into the second housing case.
Advantageous developments of the invention are claimed in the subclaims.
The trigger it in accordance with the invention for initiating pyrotechnic elements is composed of two housing cases. The first housing case surrounds a stitch and control unit, for example in the case of an unfinished or base fuse the so-called hybrid. The hybrid comprises inter alia the electronic circuit arrangements for addressing a fuse and, if applicable, for fixing the ignition point. Connected to this first housing case there is a second housing case which contain the charge body. This is, for example, in the case of a detonating fuse, the detonating capsule that is charged with the initiating detonating agent or, in the case of a belt tightener, the propellent charge for the generation of gas. Going right into this second housing case is the ignition means that is connected to the switch and control unit and which is not surrounded by the first housing case. The switch and control unit can consist of a printed circuit board on which sensitive electronic components are arranged. Owing to the fact that the switch and control unit is surrounded, in accordance with the invention, by a stable housing case, it can even be handled by automatic handling and loading machines for the mechanical assembly of a trigger unit without the electronic components being endangered. Moreover, storage and further processing are simple and inexpensive on account of the compact form.
Since the switch and control unit is surrounded by its own housing case, in view of the diameter of this housing case it is not necessary to pay any heed to the diameter of the housing case for the charge body. This is advantageous, for example, if the switch and control unit is accommodated in an IC package or, for example, bulky capacitors are used whose dimensions exceed the diameter of the housing case of the charge body. In this case, the diameter of the housing case for the switch and control unit can be greater than the diameter of the housing case for the charge body.
Owing to the fact that the charge body and the switch and control unit are arranged separately from each other in their own respective housing cases, it is possible, moreover, to surround the switch and control unit with a housing case that has a substantially greater wall thickness than the housing case of the charge body, for example the detonating capsule of a fuse. As a result of this equipping, the sensitive electronic components of the switch and control unit are not only protected against damage during handling, in the case of mechanical assembly, but also against the influences to which the trigger units are subject during their use. For example in the case of detonating fuses, in particular if, in the case of blasting at time intervals by detonating fuses, great dynamic pressure, shock and/or impact loads are exerted on the not yet ignited fuses, the so-called hybrid, the switch and control unit for fuse-addressing and for fixing the ignition point, is protected from these effects of pressure and impact on account of the greater wall thickness of the housing case before there is premature failure. The wall thickness and, in particular, the material of the housing case can be matched to the respective case of loading. So that an electronic fuse is optimumly protected against the effects of preceding fuse explosions, in particular with blasting at intervals, it is possible to avoid damage to the hybrid on account of pressure and shock effects in the beat possible way by means of the choice of the materials, for example steel, brass or copper. In order to be able to withstand the effects of the pressure in an optimum manner, in particular when there is blasting at intervals, the first housing case should withstand a dynamic pressure load of at least 100 MPa without deformation. Separate protection measures as used in the case of known fuses, for example the fitting of reinforcing or protecting tubes over the sensitive portion of the electronics unit, are superfluous.
In a further advantageous development of the invention, the switch and control unit is to be embedded in the first housing case in a hardened, non-metallic material. This can be effected in a preceding separate step of manufacture or, if the switch and control unit has been inserted into the first housing case, it is possible, for example, for plastics material, preferably polyvinyl chloride (PVC), polyurethane (PU) or else polyamides (PA), to be injection-moulded around it. Encapsulation, preferably with epoxy resins, is likewise possible. As a result of the injection-moulding or encapsulation, the switch and control unit is not just fixed in its position. The first housing case, as a result of being completely filled with the corresponding material, attains additional elastic rigidity against external pressure and shock effects.
The terminal contact
Bornheim Wilhelm
Heinemeyer Friedrich
Petzold Jan
Schäfer Heinz
Zimmermann Jürgen
Antonelli Terry Stout & Kraus LLP
Nelson Peter A.
Orica Explosives Technology PTY Limited
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