EP0681158B1 - Explosive chain - Google Patents

Description

The invention relates to an explosive chain with a variety from the ignition stages to be controlled, each of which Explosives are assigned. Such explosive chains are used in particular in mining, with the mine for example a hundred or more holes drilled in each used an explosive device with an associated detonator and the drill holes are closed with plugs. To one To ensure effective degradation, it is important that the Detonate explosive devices one after the other in a predetermined order, the interval between successive firings is typically between 30 and 50 ms.

From US-A-4 099 467 an explosive chain is known in which each ignition level one detonator and one in series with it contains lying thyristor switch, its control electrode with the tap of the detonator of the previous one Stage containing voltage divider is connected. Will the previous igniter activated, its resistance changes from an initially low value to practically infinite, whereby the thyristor switch of the following stage turns on and the next current pulse with him in series trigger detonator.

There is a fuse in parallel with each detonator, which should ensure that the triggering of the next Level and thus necessary for the advancement of the explosive chain Resistance change also occurs when on there is no igniter at one point. This fuse however forms a short circuit bridge and increases the Power consumption is considerable.

Another difficulty is that such An additional fuse in each ignition level represents discrete component to be inserted. Will the fuse in a printed circuit through a weak trace section realized, so are in the manufacture of printed circuit board adhering to exact tolerances, what to leads to an increase in price.

Is a detonator connected, but in the way erroneous that, despite being triggered, not immediately, but first detonating the assigned explosive charge (usually between 0.5 and 1.5 s later) becomes high-resistance, this results this in an excessively long delay within the Explosive chain, so that the pressure wave at the shock absorber is not in the programmed way can spread. In one Fall also reduces the reliability of the explosive chain significantly because of the distance between the electrical sequence and the explosion wave is greatly shortened.

Similar problems exist with that of US-A-4,760,791 known explosive chain. There is a transistor for each detonator connected in parallel, the missing at the igniter Place current and prevents the firing order at the Point of a missing detonator is interrupted. To the parallel connection from the igniter and transistor is also a Fusible safety device in series, which should prevent a not the detonator, which immediately becomes high-resistance, transmits the impulse delayed until the actual detonation. The Difficulties described above are also known to this Explosive chain given.

An even more serious problem is that a Another transistor is used so that it is used as intended Operation of the circuit alloyed to a short circuit connection for the ignition current pulse. There this destroys the transistor, can be done on the known Explosive chain no functional test before the actual one Carry out an operation. Nor is reuse of the electronic circuit part of the explosive chain possible. Finally, there is a risk that the little resilient Base connections of this transistor through the considerable Currents are blown out even before the detonator is activated.

It is also necessary to start at the beginning of the chain insert your own activation link so that it is not possible is, explosive chains of the desired length simply by cutting them off of greater length or joining together shorter pieces to manufacture.

Another explosive chain is described in DE-B-2 356 875, in which each ignition level except the actual igniter has one Oscillator, a frequency divider and two driver stages contains. The one coming from the previous ignition level Trigger pulse actuates the first driver stage, which in turn a switch for driving the oscillator, the Frequency divider and the second driver stage closes. Of the Output of the frequency divider provides the trigger signal for the in the explosive chain subsequent ignition stage, while the second Driver stage operated another switch, via which the Igniter is activated. Each ignition stage also contains one Capacitor for storing all the necessary for ignition Energy.

The impulse is passed on regardless of Presence and functionality of the igniter; the Circuitry requires one for practical explosive chains unacceptable circuit effort.

DE-B-1 287 495 is an explosive chain with each Features specified in the first part of claims 1 and 2 known in which the transfer of the control signal from a Ignition level to the next simply by changing the switching state of the semiconductor switch provided in each stage is effected. This explosive chain therefore remains functional even if individual detonators are missing or not working properly become high impedance. Because every semiconductor switch only then Become conductive and activate the ignition device assigned to it can if the semiconductor switch of the previous Has switched stage, the intended firing order is inevitable adhered to. Faulty assembly of the explosive chain cannot cause when turning on the power source the explosive chain at about two different places at the same time starts to ignite.

However, the well-known explosive chain requires every ignition level at least one capacitor for pulse transmission from one ignition stage to the next. Because of these capacitors does not fully integrate the known circuit.

This circuit also needs its own, the first ignition stage upstream switching element for initiation the chain so that it is - at least on the side of the first Ignition level - do not lengthen or shorten as you like leaves.

An object of the invention is an explosive chain specify, on the one hand, has the advantage that it works properly even at individual points an igniter is not provided or is faulty, in particular does not immediately become high-resistance when activated, on the other hand one Execution in integrated circuit technology favors.

The solution to this problem is specified in claim 1. The explosive chain then trained comes with an uncomplicated Circuit without capacitors, can therefore be without integrate more, and yet meets all requirements to operational safety even if it is improper or incorrect assembly.

Another solution to this problem is given in claim 2. This circuit uses the same capacitor for two successive ignition stages are used, see above that the entire explosive chain only had half as many capacitors required as the state of the art, without this in operational safety to be inferior.

Claims 4 to 7 relate to various Possibilities in the first stage firing order with a Start pulse. Thereby is the measure of the claim 5 advantageous in that it allows minimal Circuit effort of the explosive chain all ignition levels the same build up. An explosive chain for a desired number of Accordingly, detonations can easily be from a longer or continuously cut assembly or be generated by piecing shorter lengths.

The design according to claim 8 is useful in so far than the explosive chain links, each surrounded by a housing are the same and incorrect wiring of each Ignition levels is avoided.

Figur 1 einen Teil einer Sprengkette,

Figur 2 eine der Figur 1 ähnliche Darstellung einer Sprengkette gemäß einem Ausführungsbeispiel der Erfindung

Figur 3 eine Variante der Schaltung nach Figur 2,

Figur 4 ein weiteres Ausführungsbeispiel einer Sprengkette,

Figur 5 ein Impulsdiagramm der von einer Stromquelle zum Betrieb der Sprengkette nach Figur 4 erzeugten Stromimpulse,

Figur 6 eine Ausgestaltung für die in der Zündfolge erste Zündstufe, und

Figur 7 eine Variante der Sprengkettenschaltung nach Figur 2 mit einer weiteren Maßnahme zur Auslösung der ersten Zündstufe.

Embodiments of the invention are explained below with reference to the drawings. In the drawings shows

FIG. 1 shows part of an explosive chain,

Figure 2 is a representation similar to Figure 1 of an explosive chain according to an embodiment of the invention

FIG. 3 shows a variant of the circuit according to FIG. 2,

FIG. 4 shows a further exemplary embodiment of an explosive chain,

FIG. 5 shows a pulse diagram of the current pulses generated by a current source for operating the explosive chain according to FIG. 4,

FIG. 6 shows an embodiment for the first ignition stage in the ignition sequence, and

7 shows a variant of the explosive chain circuit according to FIG. 2 with a further measure for triggering the first ignition stage.

In the explosive chain circuit according to FIG. 1, the individual ignition stages S1 , S2 ,... Lie parallel to one another and in each case between two supply lines A and 0 , which are connected at the right end in FIG. 1 to a DC power source (not shown). The DC power source produces an output voltage of 50 V on line A compared to the earthed line 0 .

Each of the identical ignition stages S1 , S2 , ... contains a series circuit between a supply line A , 0 , consisting of a thyristor T and an ignition device ZE , which has two detonators Z1 , Z2 connected in series. Each detonator Z1 , Z2 is used to trigger an explosive charge (not shown). In the circuits described here, detonators with a built-in delay of 0.5 to 1.5 s are used.

The control electrode of the thyristor T is connected via a Zener diode ZD (Zener voltage: 35 V) at the connection point P between a resistor R1 (2.2 KΩ), which has its other end connected to the supply line A , and a capacitor belonging to the preceding ignition stage S1 C (22 µF), whose other electrode is connected to supply line 0 . The connection point P is also connected via a diode D to the connection point between the thyristor T and the ignition device ZE of the previous ignition stage. A resistor R2 (100 Ω ) is connected between the control electrode and the cathode of the thyristor T. Another resistor R3 (5 Ω) lies between the connection point of the cathodes of the thyristor T and the diode D on the one hand and the ignition device ZE . A fourth resistor R4 (470 Ω) bridges the ignition device ZE .

The resistors R1 and R4 are dimensioned such that when the voltage of 50 V is applied to line A, the potential at connection point P is not sufficient to switch through thyristor T of stage S2 . Only when the thyristor T of the preceding stage S1 conducts does the point P reach a potential (50 V minus the voltage drop across the thyristor T and across the diode D ) at which the capacitor C rises to such a high level via the resistor R1 Value can charge that the ignition voltage for the thyristor T of stage S2 is reached. Taking into account the Zener voltage (35 V) of the Zener diode ZD, this value is approximately 15 V, which is sufficient for switching the thyristor T.

The delay with which the thyristor T of stage S2 becomes conductive after the thyristor T of stage S1 has been switched on depends on the time constant of the RC element formed by resistor R1 and capacitor C. The required delay of 30 to 50 ms can be achieved by appropriate dimensioning.

As can be seen from the above description, the transmission of the trigger pulse from stage to stage with the specified delay time is independent of the ignition device ZE . This means that the circuit works properly even if one or several ignition stages has been forgotten to insert an ignition device.

The same applies if an ignition device is present is, but is not working properly and not immediately becomes high resistance when applied. In this case the Fuze its very low original resistance like that hold for a long time until the actual explosive charge explodes (and thus destroys the detonator). In practice it has shown that a few percent of all detonators are such Show behavior.

If two detonators Z1 , Z2 are connected in series, as is assumed in FIG. 1, the probability that both detonators display this malfunction is extremely low. In this way, it can practically be avoided with certainty that short-circuit current is drawn from the current source during the entire period from switching on the thyristor T to detonation of the explosive charge (that is to say for about 0.5 to 1.5 s). The resistor R3 is provided for the very rare case that the two igniters Z1 , Z2 in series become high-resistance at the same time.

In the explosive chain according to FIG. 1, all ignition stages S1 , S2 , ... are constructed identically. It is therefore possible to produce explosive chains with a desired number of ignition stages by simply cutting them off from a greater length. In this case, the capacitor C for generating the ignition voltage, which is otherwise in the previous stage, is missing in the first stage in the firing sequence ( S1 in FIG. 1). The ignition of the first stage S1 takes place without delay when the supply voltage is applied to the line A via the Zener diode ZD and the resistor R3 , since the circuit elements D , R3 and R4 of a previous stage are not present.

The circuit according to FIG. 2 differs from that according to FIG. 1 in that a current source is used which alternately gives current pulses on two channels to which the supply lines A and B are connected, which preferably do not overlap one another. The ignition stages are alternately connected to the supply lines A and B.

In the circuit according to FIG. 2, the ignition delay from one stage to the next is thus predetermined by the pulse current source. The individual ignition stages S1 , S2 , ... therefore do without an RC element, and the resistor R1 present in FIG. 1 can be omitted. Furthermore, the Zener diode ZD provided in FIG. 1 is replaced in the circuit according to FIG. 2 by a resistor R5 (1 KΩ).

Since each ignition stage is only activated in FIG. 2 when the thyristor T has become conductive due to a corresponding signal on its control electrode and a pulse is present on the supply line A or B , it is not necessary to provide a series connection of two detonators as the ignition device . Even if the individual detonator does not become properly high-resistance when activated, the current consumption is limited to the short time interval (for example 10 to 20 ms) during which the current pulse is present on the supply line A , B.

In the circuit according to FIG. 2, the parallel connection of two detonators Z1 and Z3 with a respective series resistor R3 is assumed as a variant. This parallel connection only represents an economy measure. In such a case, two detonators are acted on simultaneously, so that the correspondingly assigned explosive charges detonate simultaneously. The resistor R3 enables the thyristor T to turn on even when the respective igniter Z1 , Z3 is short-circuited and to charge the capacitor C of the subsequent stage.

Otherwise, similar to the circuit of FIG. 1, the capacitor C (4.7 μF) only charges when the thyristor T of the previous ignition stage is conductive. At a certain potential of the capacitor C , the ignition voltage for the thyristor T is reached, so that the latter is switched through by the subsequent current pulse on the associated supply line A , B.

In FIG. 2, a resistor R1 is shown in the first ignition stage S1 , which is connected to the same supply line A as the thyristor T of the first ignition stage S1 . This resistor R1 is used in connection with a corresponding overvoltage pulse (80 ~ 100 V / 1 ms) on the supply line A for the initial ignition of the explosive chain.

If you want to build the explosive chain consistently in the same way, an identical resistor R1 can be provided for all ignition stages S1 , S3 , ... which are connected to the same supply line ( A ). Such a resistor R1 (which is not required for the function of the circuit) is shown in dashed lines in the ignition stage S3 in FIG.

With a pulse duration of 1 ms, it is impossible to switch through for all subsequent stages, since the associated capacitor C is only charged to approximately 5 V. Only the first stage S1 , which does not contain a capacitor, can switch through with such a short pulse. This ensures that the firing sequence always begins at the beginning of the chain.

The circuit according to FIG. 3 is largely similar to that according to FIG. 2, but differs in that a common capacitor is provided for two successive ignition stages. In FIG. 3, this is the capacitor C (4.7 μF) located in the ignition stage S1 , which is used to generate the control voltages for the thyristors T of the ignition stages S2 and S3 . Otherwise, the circuit of FIG. 3 is the same as that of FIG. 2, the diode D being replaced by a resistor R6 (2.2 KΩ).

The end of the capacitor C facing away from the supply line 0 is connected, as in FIG. 2, to the control electrode of the thyristor T of stage S2 via a resistor R5 (1 KΩ). The same electrode of the capacitor C is also connected via a resistor R7 (4.7 KΩ) and the resistor R5 (1 KΩ) to the control electrode T of the ignition stage S3 .

If resistor R1 is not provided, the two series resistors R7 and R5 could also be combined to form a resistor (5.7 KΩ). The embodiment shown in FIG. 3 was chosen for the reasons described above for the equality of all the links in a chain, again the resistance R1 (5 KQ) shown in broken lines in stage S3 is not required for the function.

As soon as the thyristor T of the ignition stage S1 conducts, the capacitor C charges up to about 15 V via the resistor R6 . This value is sufficient to ignite the thyristor T of stage S2 . If the thyristor T of stage S2 switches on at the next current pulse on the supply line B , the capacitor C is further charged to about 34 V via the resistor R2 (100 Ω) and the resistor R5 (1 KΩ), which now takes into account the resistors R7 and R5 are sufficient to ignite the thyristor T of the ignition stage S3 , which then switches on when the next pulse occurs on the supply line A.

In the circuit according to FIG. 3, as in FIG. 2, two ignition units connected in parallel can be provided in each ignition stage. Likewise, the initial ignition of the first stage S1 can take place via the resistor R1 provided there and an initial overvoltage pulse on the supply line A.

The circuit according to FIG. 1 works with a capacitor in order to achieve the desired delay of 50 ms between the successive ignition stages. The timer consists of the resistor R1 and the capacitor C , and the switching threshold (35 V) is determined by the Zener diode ZD .

The circuits of Figures 1 and 2 use a capacitor to pass the switching pulse from one stage to the next and to store (about 1 to 2 ms) during the gap between successive pulses on lines A and B. In the further circuit according to FIG. 4, this memory function is taken over by the thyristor itself.

The circuit according to FIG. 4 is identical to that according to FIG. 2, the diode of FIG. 2 being replaced by a resistor R6 (2.2 KΩ) similar to FIG. 3 and a resistor R8 (1 KΩ) being provided instead of the capacitor C.

A further difference from the circuits according to FIGS. 2 and 3 is that the pulses supplied by the current source via the supply lines A , B connect directly to one another in time and each pulse according to FIG. 5 has an initial interval of reduced voltage which corresponds to the previous pulse on the respective other supply line overlaps.

During the time interval t ₀ ~ t ₂ shown in FIG. 5, in which the full pulse (50 V) occurs on the supply line A , the thyristor T of the ignition stage S1 is switched through. Before the end of this time interval occurs at the time t ₁ the reduced initial interval (20 V) of the next pulse on the supply line B , so that now the thyristor T of stage S2 fires. However, the voltage (20 V) occurring at the cathode thereof is not sufficient to also ignite the thyristor T of the next stage S3 , which per se is supplied with the full voltage of the pulse on line A. Only after the pulse on line A has been switched off at time t ₂ does the pulse on line B rise to the full voltage (50 V) at time t ₃ , so that the thyristor T of stage S2 can now fully switch through and the supplies voltage required to ignite the thyristor T of the next stage S3.

As with the circuits according to FIGS. 2 and 3, a further resistor R1 (10 KΩ) is also present in the circuit according to FIG. 4 in the first stage S1 , which is used in conjunction with the first overvoltage pulse shown in FIG. 5 for the initial ignition of the explosive chain.

Again, the same resistor R1 is not required for the function of the circuit in the other stages with the exception of the first ignition stage S1 and is therefore only shown in broken lines. As above, it can be provided in order to be able to construct the entire ignition chain from identical links. Likewise, two igniters connected in parallel can also be provided in the circuit according to FIG. 4 in the ignition stage.

FIG. 6 shows a variant for the first ignition stage S1 of an explosive chain, which is otherwise constructed in accordance with FIG. 2. The same variant is also suitable for the circuits according to FIGS. 3 and 4.

In the circuit according to FIG. 6, the resistor R1 shown in FIG. 1 is replaced by a parallel circuit consisting of a resistor R1 '(> 100 KΩ) and a capacitor C2 (1 μF). This ensures that only the first pulse of 50 V applied to supply line A can ignite while capacitor C2 is still empty in thyristor T of first stage S1 . The resistor R1 ' causes the capacitor C2 to discharge so slowly that all further pulses on the supply line A no longer reach the control electrode of the thyristor T.

In the circuit according to FIG. 6, the first ignition stage S1 of the explosive chain has a special configuration; this means that the explosive chain begins to work as soon as the pulse current source is switched on without an overvoltage initial pulse being required; on the other hand, it is no longer possible to produce a functional explosive chain simply by cutting off a longer, prefabricated explosive chain.

In the circuit variant shown in FIG. 7, the thyristor T of the first stage S1 can also be ignited without an initial overvoltage pulse. The circuit according to FIG. 7 assumes that a current pulse is briefly generated on both lines A, B for initial ignition, which current is added via the two resistors R1 , R1 "(10 KΩ each) provided here. to build the entire explosive chain from identical links and thus to obtain a functional explosive chain by simply cutting off a greater length, provided that the resistances R1 , R1 "are doubled at every (or every other) ignition stage.

In the explosive chain circuits according to Figures 2 to 4 are the even-numbered ignition levels among each other and also the odd-numbered ones Ignition levels identical to each other. To ensure, that when cutting off such an explosive chain of a longer length an ignition stage of the right type does not form the first stage of the chain or when joining together two similar ignition levels can be combined successive stages in pairs in common Housing (not shown) can be arranged.

The in the description of the figures above each in Brackets given dimensions of the different Circuit elements only represent typical values of exemplary embodiments represents.

Claims (10)

1. An explosive chain including detonator stages (S1, S2, S3, ...) to be triggered in succession, wherein

   each detonator stage (S1, S2, S3,...) includes detonator means (ZE) connected in series with the output circuit of a semiconductor switch (T) for detonating at least one explosive charge,

   the series circuits thus formed are connected in parallel between supply leads (A, B, 0) connected to a power source, and

   the control input of the semiconductor switch (T) of each detonator stage (S2, S3, ...) is connected to the junction between the semiconductor switch (T) and the detonator means (ZE) of the respective preceding detonator stage (S1, S2, ...),

      characterised in

   that the supply leads (A, B, 0) are subdivided in two channels (A, 0; B, 0) to which pulses are alternately applied from the power source and successive detonator stages (S1, S2, S3,...) are alternately connected to the one and the other channel, and

   that each pulse on one channel has an initial interval (t₁~t₃) of lower voltage which overlaps the respective preceding pulse on the other channel.
2. An explosive chain including detonator stages (S1, S2, S3, ...) to be triggered in succession, wherein

   each detonator stage (S1, S2, S3,...) includes detonator means (ZE) connected in series with the output circuit of a semiconductor switch (T) for detonating at least one explosive charge,

   the series circuits thus formed are connected in parallel between supply leads (A, B, 0) connected to a power source, and

   the control signal for the semiconductor switch (T) of each detonator stage (S2, S3, ...) is the voltage of a capacitor (C) which is adapted to be charged via the semiconductor switch (T) of the respective preceding detonator stage (S1, S2, ...),

      characterised in

   that the supply leads (A, B, 0) are subdivided in two channels (A, 0; B, 0) which are alternately supplied by the power source and successive detonator stages (S1, S2, S3, ... ) are alternately connected to the one and the other channel, and

   that a common capacitor (C) is provided for each pair of successive detonator stages (S1, S2), the capacitor being adapted to be charged via the semiconductor switch (T) of the detonator stage preceding this pair to a first value, and to be charged via the semiconductor switch (T) of the first detonator stage (S1) of the pair to a second, higher value.
3. The explosive chain of claim 2, wherein the capacitor (C) is connected to the control input of the semiconductor switch (T) of the first detonator stage (S1) of the pair via a first resistor (R5) and to the control input of the semiconductor switch (T) of the second detonator stage (S2) of the pair via a second resistor (R7) which is larger than the first resistor (R5).
4. The explosive chain of any one of claims 1 to 3, wherein the control input and the output circuit of the semiconductor switch (T) of the first detonator stage (S1) in the firing sequence are connected to the same channel.
5. The explosive chain of claim 4, wherein the power source supplies an overvoltage pulse to the first detonator stage (S1) in the firing sequence.
6. The explosive chain of claim 4, wherein the control input of the semiconductor switch (T) in the first detonator stage (S1) in the firing sequence is connected to the respective channel via an R-C element (R1', C2).
7. The explosive chain of claim 4, wherein the control input of the semiconductor switch (T) of the first detonator stage (S1) in the firing sequence is connected to both channels, and the power source generates a pulse on both channels for triggering the first detonator stage (S1).
8. The explosive chain of any one of claims 1 to 7, wherein pairs of detonator stages (S1, S2; ...) are combined to form circuit elements each accommodated in one housing, with all circuit elements having the same construction, and wherein only the first detonator stage (S1) in the firing sequence, which has no preceding stage, is adapted to be activated by an initial pulse.
9. The explosive chain of any preceding claim, wherein each detonator means (ZE) includes two detonators (Z1, Z2) connected in series.
10. The explosive chain of any preceding claim, wherein each detonator means (ZE) contains two detonators (Z1, Z3) connected in parallel.

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