Installation for programmable pyrotechnic shot firing

Abstract

Programmable pyrotechnical firing installation comprising a programming and firing control unit (8), a programming and control line comprising two conductor wires (6a, 6b) and a plurality of electronic detonators (4) mounted in parallel on this two-wire line, wherein the programming unit (8) comprises means (9, 10) for establishing a continuous voltage between the two wires (6a, 6b), means (9, 10) for producing pulses of this voltage so as to form coded signals, and means (11, 9) for reading the current variations existing on the two-wire line, wherein every detonator comprises an electronic module (12) that has means (14, 17) suitable for producing, in response to certain of the coded signals of the programming unit (8), current pulses in the two-wire line (6a, 6b) for forming coded signals.

Description

In mines and quarries the breaking of rocks is typically carried out by means of explosives.

A firing program consists of making a plurality of drill-holes in the rock, which are filled with explosives with, for every drill-hole, a detonator that permits the firing. Some of these detonators are electronically controlled, which makes it possible to program the setting off of the explosions according to a predetermined firing plan.

The execution of a firing plan consists, therefore, after having arranged all the detonators in the drill-holes that have been made and connecting them to a control unit, of identifying every detonator by a serial number and applying to it a delay time which will determine the ignition of the charge in relation to a general firing signal.

The present invention relates to such a programmable pyrotechnical firing installation, in which all the detonators are connected to the control unit by wires.

Conventionally, an electronic detonator comprises a pyrotechnical percussion cap, an energy reserve, an electronic pilot and two electrical conductors that connect the electronic pilot to a firing line which runs over the ground from a central programming and control unit. The electronic pilot comprises an on-board microprocessor by means of which communication can be established between the detonator and the central unit. The microprocessor is programmed or programmable so as to be able to receive requests issued in the firing line by the central unit and to respond to these requests either in the direction of the central unit or in the direction of the energy reserve, which it will release with a specific time delay when the firing order has been received from the central unit. The programming of the on-board microprocessor in the electronic pilot of the detonator can be carried out a priori before its positioning in the firing field or, as is the case for the invention, a posteriori after it has been put into position. The firing line on the ground also serves to provide the electrical energy required for filling the energy reserve, which takes place just before the firing in order to comply with the safety requirements that demand that the detonators must be inactive up to the last moment.

It must be borne in mind that a firing line may have a length of about a kilometre. For this reason, with the current installations it is relatively simple to transmit from the control unit signals to the address of every detonator, however far this may be removed from the control unit, since the required energy to be provided for these signals so that they will reach their target is controlled totally from the control unit. On the other hand, a detonator has very little on-board energy and if one wants it to be able to respond to the central unit, it will be noted that the limited power of the signals which it emits suffers a strong attenuation that may make them inaudible by the central unit if the detonator-emitter is far away from same on the firing line.

The present invention provides a solution to this bi-directional communication problem between a central unit and each one of the detonators of a firing line, a simple and economical solution.

To this end, the invention relates to a programmable pyrotechnical firing installation comprising a programming and control unit for the firing, a programming and control line comprising two conductor wires and a plurality of electronic detonators mounted in parallel on this two-wire line, wherein the programming unit comprises means for establishing a continuous voltage between the two wires, means for producing pulses of this voltage so as to form coded signals and means for reading the current variations existing on the two-wire line and wherein every detonator comprises an electronic module that, in response to certain of the coded signals of the programming unit corresponding to requests from same, can produce current pulses in the two-wire line for forming coded signals.

In other words, when a detonator, whatever its position on the firing line, must respond to a request of the central unit, it will produce in the filar firing line excess current peaks, for example by closing the line on a calibrated resistor within a given time and this in dependence on a pulses program corresponding to a code generated by the on-board microprocessor, which excess current peaks are immediately detectable by the central unit, which by means of a resistor will convert them into a modulated voltage that can be interpreted by its microprocessor, this forming the response of the detonator in question to the request of this central unit.

Other characteristics and advantages of the invention will be noted from the description given below by way of non-limitative example, of an exemplified embodiment.

Reference will be made to the attached drawings, wherein:

FIG. 1 is a diagram illustrating a pyrotechnical firing installation,

FIG. 2 illustrates diagrammatically a central programming and control unit of the installation,

FIG. 3 is a functional diagram of that part of the electronic pilot of every detonator involved in the dialogue with the central programming and control unit.

To carry out a firing program, holes 1 are drilled in a rock 2 from, for example, the ground 3. In each of these drill-holes 1, detonators 4 and explosive charges 5 are placed, every detonator 4 being connected to firing line 6 on the ground by conductors 7. A central programming and control unit is shown at 8, connected to the firing line 6.

This unit 8, see FIG. 2, comprises a microprocessor 9 which acts on a device 10 for the supply of a continuous voltage between the two wires 6a, 6b of the line 6 and which permits inserting into this continuous voltage drop sequences so as to form slots corresponding to any type of binary code of a signal. Furthermore, the central unit 8 is provided with a device 11 for converting into voltage the current circulating on the line 6a, 6b in order to produce variations of this current that can be understood by the microprocessor 9.

The electronic pilot 12 of the detonator illustrated diagrammatically and partially in FIG. 3, comprises a voltage regulator 13, the input of which is connected to the line 6a, and the output to an on-board microprocessor 14, in order to form a power supply of this microprocessor 14 increased by a capacitor 15 that permits smoothing the drops in voltage in the line 6. This pilot 12 also comprises a circuit 16 for detecting codes carried by the line 6, the input of which is also connected to the line 6a and the outlput of which is directed towards the microprocessor 14. Between the lines 6a and 6b the electronic pilot 12 has a voltage-drawing circuit 17, for example a transistor and a resistor, controlled by the microprocessor 14. Finally, the microprocessor 14 controls a switch 18 of the line 6a, in a manner as will be explained below.

Each one of the detonators 1 is connected to the two-wire line 6a, 6b parallel to same at the point A, B (FIG. 3). In reality, four wires 19, 20, 21, 22 come from this electronic pilot 12, which form the conductors 7 of FIG. 1. The wires 19 and 20 permit connecting the pilot to the wires 6a and 6b of the firing line. The line 6a has a section 23 inside the pilot 12, which comprises the switch 18 and which comes out of the pilot by way of the line 21 which becomes 6a at the level of the ground. In the same manner the line 6b has a section 24 inside the pilot, which by way of the conductor 22 comes out of the drill-hole to form the wire 6b of the firing line at the level of the ground. At the time when the detonators are positioned in the drill-holes, the switch 18 is open. The electronic pilots are connected the one following the other. Understood under this mounting method is that the first detonator connected to the unit 8 is mounted in series on the line 6a, 6b when the switch 18 is open. When the switch 18 is closed, this detonator is mounted in parallel with the next one on the line 6a, 6b.

When the firing line has been realised, the central unit 8 establishes a voltage of, for example, 24 or 48 volt at the terminals of the conductors 6a, 6b. This voltage, regulated by the device 13, constitutes the power supply of the processor 14 as well as the charge of the capacitor 15. By cutting this voltage by means of the device 10, the microprocessor 9 of the central unit 8 transmits to the pilot 12 a serial number recorded by the microprocessor 14, and a certain delay time. The operating sequence of the microprocessor 9 may then comprise a request (a binary signal on the voltage of the line 6) to which the microprocessor 14 will respond by acting on the current-drawing circuit 17 to create excess voltage peaks which, converted by the device 11, will be assimilated as a response to the request by the microprocessor 9. The last order transmitted by the microprocessor 9 to the onboard microprocessor 14 will be to close the switch 18. At this moment, the pilot of the next detonator is in the same state with regard to the central unit 8 as the preceding pilot and the programming sequence can recommence.

When all the detonators have been programmed in this manner, the firing installation is ready to operate. The microprocessor 9 may comprise in its program other stages and other requests concerning the detonators. It will then transmit a general order to all the detonators to proceed with the charging of the energy reserve, not illustrated in the figures, possibly followed by a verification of the state of this reserve, and will finally transmit to all the detonators a firing signal.

Claims

1. A programmable pyrotechnical firing installation comprising a programming and firing control unit (8), a programming and control line comprising two conductor wires (6a, 6b) and a plurality of electronic detonators (4) mounted in parallel on this two-wire line, wherein the programming unit (8) comprises means (9, 10) for establishing a continuous voltage between the two wires (6a, 6b), means (9, 10) for producing pulses of this voltage so as to form coded signals and means (11, 9) for reading the current variations existing on the two-wire line and in that every detonator comprises an electronic module (12) that has means (14, 17) suitable for producing, in response to certain of the coded signals of the programming unit (8), current pulses in the two-wire line (6a, 6b) for forming coded signals.

2. A firing installation according to claim 1, wherein every electronic detonator module (12) comprises a switch (18) of the two-wire line (6a, 6b), which normally is open and is closed in response to a signal emitted by the programming unit (8).