Circuit Arrangement For Rocket Launchers

Abstract

A rocket launcher firing control circuit in which a series of rockets are fired either individually or automatically in sequence under the control of a mode selector switch control the mode of operation of a clock pulse generator, a counter counting the generator pulses and a decoder controlled by the counter output for firing the detonator caps of a series of rockets in sequence via thyristors connected in parallel to a power source. The control electrode of each thyristor is connected to a separate output of the decoder and the generator is controlled by a digital control unit so that the operation of the system is not impaired by the presence of a faulty rocket detonator unit.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a circuit arrangement for rocket launchers, particularly for triggering detonator caps in such a manner as to permit firing rockets either in sequence or individually.

The firing of a rocket propelling charge is initiated by a so-called detonator cap which is disposed in the charge. Such detonator cap contains a heating wire which is enclosed by a quantity of powder. When the heating wire is heated, the quantity of powder is ignited so that the outer shell of the detonator cap explodes and fires the rocket propellant charge.

With a plurality of rockets arranged next to one another to constitute a rocket battery or batteries it is necessary, for example, that the rockets be fired either one after the other at certain time intervals, i.e., in sequence, or that each individual rocket be fired separately. To meet this requirement, an electromagnetic circuit arrangement is known which is operated by a stepping switch mechanism. The entire circuit arrangement is built into the rocket starting device.

This circuit arrangement has the drawback that the presence of a short circuit in one of the firing lines leading to one rocket prevents the firing of the detonator caps which are connected to the firing lines following the short-circuited line.

Furthermore, it is possible for the mechanical follower in the stepping switch mechanism to malfunction during an acceleration of the circuit arrangement. Such an acceleration may occur, for example, when the rocket launchers are mounted on airborne bodies.

A soiling of the contacts of the switching mechanism is also very detrimental to perfect operation.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a circuit arrangement which eliminates the above-mentioned drawbacks.

A further object of the invention is to assure fault-free firing of a plurality of rockets either in sequence or individually from launchers disposed on the ground or from those mounted on airborne bodies.

These and other objects are accomplished according to the present invention by the provision of means which initiate the functions "sequential firing" or "individual firing" under the control of an operational mode selection switch and a firing key and through the application of a supply voltage, and which assure the automatic sequence of the firing process even when there is a fault in one or more of the firing lines.

The supply voltage can be switched, during the sequential firing operation, from an electronic switch to a plurality of thyristors in succession, a clock pulse generator controlling the electronic switch as well as the thyristors, the latter via a counter and a decoder. The clock pulse generator provides for this purpose a frequency which has a varying value.

For the "individual firing" operation, the clock pulse generator, which simultaneously controls a counter and an electronic switch, is switched by means of a digital control unit to produce a high clock pulse frequency. This high clock pulse frequency continues until a current sensor locates a closed firing circuit and furnishes a signal to the digital control unit. Then the clock pulse generator switches back to the original frequency, the firing voltage is applied to the thryistor of the closed firing circuit and the digital control unit furnishes a stop signal to the clock pulse generator when the thyristor has fired. The digital control unit will not furnish a stop signal to the clock pulse generator when there is a permanent short circuit in one of the firing lines.

The advantage of the present invention is that no memory elements are provided in the circuit arrangement. Thus it results that only the perfect detonator cap which is next in line in the given sequence is fired, regardless of the presence of a short circuit or an interruption in the preceding firing line. Even with a short circuit or an interruption in one firing line, the "series firing" and "individual firing" operations are performed. The circuit arrangement can also be built into the rocket launching devices in place of the previously employed electromagnetic circuit arrangement.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a circuit diagram of one preferred embodiment of the present invention.

FIG. 2 illustrates one embodiment of a applied clock pulse generator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The firing circuit of the illustrated embodiment includes a firing unit 1 in which a plurality of, e.g., 10, thyristors are connected together, only three thyristors 2, 3 and 4 being shown. The outputs of the thyristors 2, 3 and 4 are connected in a standard manner to heating wires belonging to detonator caps (not shown). The control inputs of the thyristors are conductively connected to a clock pulse generator 7 via a decoder 5 and a binary coded decimal counter 6, the clock pulse generator 7 being fed by the supply voltage for the system.

Two control inputs of the clock pulse generator 7 are conductively connected to two outputs of a digital control unit 8. One of the connecting lines is required for switching the frequency of the clock pulse sequence and the other line is required to switch off the clock pulse generator 7.

The digital control unit 8 has a total of three inputs: the first input is connected to the output of the clock pulse generator 7; the second input is electrically connected to an operational mode selector switch 9; and the third input with the signal output of a current sensor 10.

The supply voltage inputs of the thyristors 2, 3, 4, etc., are connected, via the operating circuits of current sensor 10 and an electronic switch 11, to a firing key 12 through which the supply voltage can be applied to the electronic switch 11 as well as to the clock pulse generator 7. The control input of the electronic switch 11 is in electrically conductive connection with the output of the clock pulse generator 7.

The mode of operation of this circuit arrangement will first be described for the sequential firing function, in which the operational mode selection switch 9 has the illustrated position and the supply voltage is applied, via electronic switch 11 and current sensor 10, in succession to thyristors 2, 3, and 4 and thus also to their associated detonator caps.

The automatic firing process of thyristors 2, 3, and 4 is initiated by the actuation of the firing key 12 and continues as follows:

First clock pulse generator 7 starts running freely and feeds pulses at its normal clock pulse frequency to the BCD counter 6. The decoder 5 converts the BCD code to a (.sup.10) code and applies in succession with each count a control pulse to the control input of each successive thyristor 2, 3, and 4, etc., each pulse having a duration of 20 msec. The time between the firing of two adjacent thyristors is 25 msec, so that in this example with 10 detonators all of the thyristors will have been pulsed once in a period of 250 msec.

Together with the timing of clock pulse generator 7, the electronic switch 11 is controlled in parallel with the control pulses and the supply voltage is applied to the voltage inputs of the thyristors 2, 3, and 4, etc., in synchronism with the control pulses. However, it will be only the thyristor which receives a control voltage at its grid and a supply voltage at its voltage input which will be fired. This AND requirement - presence of the supply voltage and the grid pulse at the same time - must always be met to fire a detonator cap.

In order to achieve the required firing sequence period of 25 msec in operation, the clock pulse generator must be so designed that it emits a clock pulse train with pulses and pulse intervals of different durations. For a time period of 20 msec the clock pulse generator 7 emits a signal representing a binary "1" which closes the electronic switch 11, i.e., renders it conductive, and simultaneously serves as a counting pulse for the BCD counter 6. A firing pulse is derived from the counter output by decoder 5. The counter 6 is set to produce an output signal representing a logic 0 at each switching on by the firing key 12 so that a continuous firing sequence from thyristor 2 to thyristor 4 is always assured.

If it should occur that the detonator cap in one of the rockets burns into a short circuit so that the launch can not be initiated, the current to that cap is interrupted after approximately 20 msec by the circuit arrangement itself, and after the current interruption there is a pause of 5 msec until the next detonator cap is fired. The circuit arrangement acts in the same manner when the input leads to one or more detonator caps have a short circuit to ground. If, however, a firing line is broken, the effect on the circuit arrangement will be the same as if the detonator cap had already been fired.

For the individual firing function, the circuit arrangement is to fire only a single thyristor and launch only one rocket. For this purpose, the operational mode selector switch 9 in the rocket launching device is moved into the position shown in the drawing in dashed lines to connect one input of control unit 8 to ground. With this switching arrangement the clock pulse frequency of the clock pulse generator 7 is switched by means of the digital control unit 8 to a higher value. As for the case of sequential operation, counter 6 is controlled to effect a count simultaneously with the closing of electronic switch 11.

If several detonator caps have been fired, the clock pulse generator 7 continues at the higher clock pulse frequency until the current sensor 10 detects a closed firing circuit. The current sensor 10, when it has recognized a closed firing circuit, furnishes a signal to the digital control unit 8 which switches clock pulse generator 7 back to the original frequency. If the current sensor 10 indicates, within a period of 20 msec, a current interruption in the recognized firing circuit, i.e., the thyristor associated with this firing circuit is being fired so that there now is an open firing circuit, the digital control unit 8 additionally furnishes a stop signal to clock pulse generator 7. The stop signal prevents a further switching to the next-following firing circuit. The next firing of a thyristor can then take place only through renewed depression of the firing key 12 so that counter 6 is set back to zero and the next closed firing circuit is located in a very short time.

If a short circuit is present in a line in the form of a previously fired detonator cap, or if there is a line short circuit to ground, the digital control unit 8 will not furnish a stop signal due to the presence of a continuous short circuit current. Rather, as in sequential operation, the current is switched off after 20 msec and after a further 5 msec it is switched to the next firing circuit. This process is automatically continued until a properly functioning firing line has been found and the firing takes place as planned. A firing circuit which has been interrupted by a defective firing line can be considered to be an open firing line. Line a in FIG. 2 serves to transmit a stop signal from the digital control unit 8 to the clock pulse generator 7. On the other hand, the signal transmitted by line b to the clock pulse generator 7 causes a change-over of the frequency of the clock pulse generator 7 from "Slow" to "Quick" or vice versa. The signal delivered by the clock pulse generator 7 through line c serves to control the binary coded decimal counter 6 of the electronic switch 11 and line b in the individual as well as in the sequential firing operational mode.

In the operational mode "Sequential firing" (switch 9 in the position as shown), there is a L-signal at the inverter located in the left upper part of the digital control unit 8, whereas a O-signal is present at the inverter output. A O-signal is then continuously applied to line a. In this operational mode no stop signal can influence the clock pulse generator 7. The L-signal deriving from the operational mode selector switch 9 results in a continuous O-signal at the output of the upper right And-gate of the digital control unit 8. Thus the current sensor 10 cannot effect line b consequently, the signal on line b follows the signal of line c.

In the operational mode "Individual firing" (switch 9 shown in the position marked by dotted lines), there is a continuous L-signal at the left input of the left lower And-gate of the digital control unit 8 because of the negation by the inverter. Thus the signal on line a can follow the signal output of the current sensor 10. The clock pulse generator 7 is not stopped if the current sensor 10 should cause a L-signal. The stopping only takes place if this signal returns to Zero. As long as the current sensor 10 has no L-signal, the line b has a O-signal. The clock pulse generator 7 operates with this signal in the highest pulse frequency. When a L-signal is present, the clock pulse generator 7 operates with the lowest frequency. The feedback to the clock pulse generator 7 through line c in the operational mode "Individual firing" is without effect on the signal on line b .

The clock pulse generator 7 shown in FIG. 2 has 3 inputs a, b and c (as shown in FIG. 1) and the power supply. The control of the input b has already been described together with the digital control unit 8. In case of a L-signal on line b, the transistor 13 is turned on.

In order to charge the capacitor 14, in this case it is only the resistor 15 that can become effective. A slow pulse sequence is produced at the unijunction transistor. When line b has a O-signal the resistor 17 acts in parallel to resistor 15 and furnishes the necessary charging resistance. Thus the frequency of the pulse sequence of the unijunction transistor 16 is increased. The output signal of the transistor 16 is fed into a flip-flop 18, the output signal of which appears on line c. The signal of line c is fed back by the digital control unit 8 through line b of the clock pulse generator 7. In the operational mode "Individual firing" the line a has a L-signal, when a L-signal appears that is released by the current sensor 10. Since a stop of the clock pulse generator 7 may only take place after appearance of a O-signal on the line a following the L-signal, this L-signal must first be converted in the clock pulse generator 7 by an inverter 19, since the subsequent flip-flop 20 only operates when the side of the pulse is positive. The flip-flop 20 can then pass the information at its input D on the positive pulse side to its output Q. Owing to the coupling between the clock pulse generator 7 and the current sensor 11, at this time only a L-signal can appear at the input D of the flip-flop 20. In case of a L-signal at the output of the flip-flop 20, the transistor 21 is turned on. An additional charging of the capacitor 16 is avoided.

The components not designated in FIG. 2 only serve to adjust the operating point and to compensate the temperature of the components.

In one embodiment of the present invention it is proposed to encase the circuit arrangement in silicon rubber to form a completely encapsulated unit. It is in this case advisable to dispose the outputs so that they are protected against short circuits and the inputs against changes of polarity. Such a case unit can easily be installed in rocket launching devices.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

Claims

We claim:

1. In a device for launching a plurality of rockets each containing a detonator device arranged in a firing circuit, a circuit for controlling the firing of the detonator devices, comprising, in combination: a firing key connected for applying firing energy to the detonator devices; mode selector switch means connected for controlling the mode of operation of said circuit and switchable between a first position in which it causes all previously unfired detonator devices to be fired in sequence when said key is actuated and a second position in which it causes one detonator device to be fired each time said key is actuated, successive actuations of said key causing successive detonator devices to be actuated; and control circuit means connected between said key, said mode selector switch means and the detonator devices for sustaining the selected mode of operation of said circuit despite malfunctions in the firing current path of one or more of the detonator devices, said control circuit means including: a plurality of thyristors each having one main electrode arranged to be connected to a respective detonator device; an electronic switch one side of which is connected to said key and the other side of which is connected in common to the other main electrodes of all of said thyristors; a clock pulse generator connected to control the operation of said electronic switch; a counter and decoder connected between said generator and the control electrodes of said thyristor; a digital control unit connected between said selector switch means and said generator for controlling the operation of said generator; and a current sensor connected for sensing the current conducted by said electronic switch and producing an output signal when it senses a current level corresponding to that drawn by an operative firing circuit, said sensor being connected to apply its output signal as an input to said control unit; wherein when said switch means is in its said first position, said pulse generator produces an output at a first frequency, composed of pulses whose duration is different from the interval between pulses, which causes each of said thyristors to be triggered into conduction in sequence by the output signals from said decoder, and said control unit is responsive to the switching of said selector switch into its said second position for causing said generator to produce an output at a second frequency higher than said first frequency upon the actuation of said key and until said sensor produces its output signal, to then produce an output at said first frequency to fire an operative detonator device, and to then stop.

2. An arrangement as defined in claim 1 wherein when said selector switch means is in its said second position, said control circuit is arranged to maintain the operation of said generator at said first frequency when the output signal from said sensor is due to a short-circuited firing circuit and until a detonator device in an operative firing circuit is fired.