US3892182A

US3892182A - Squib control circuit

Info

Publication number: US3892182A
Application number: US423082A
Authority: US
Inventors: George Salvador Covarrubias; Ernest Charles Slater
Original assignee: CBF Systems Inc
Current assignee: CBF Systems Inc
Priority date: 1973-12-10
Filing date: 1973-12-10
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01

Abstract

A control and indicating circuit for use with squib operated explosive units. The squib filaments are each connected in series with a relay winding and a small current applied to the circuit. This current operates the relay but does not explode the squib. Relay lamps connected to relay contacts are lighted when the relay is operated, indicating that the circuit and squibs are ready. In order to fire the squibs, an alarm circuit applies the charge on a capacitor to the squib filaments, melting them and exploding the powder surrounding the filaments. After this operation, the circuit applies a pulsed current to the lamps, causing them to light intermittently, thereby indicating the end of the operation. The pulsed current is also applied to the indicating lamps whenever any one of the squib supply lines is opened, as for example, when a line is inadvertently cut.

Description

United States Patent 11 1 Covarrubias et al.

1 SQUlB CONTROL CIRCUIT [75] Inventors: George Salvador Covarrubias, La Puente; Ernest Charles Slater, La Verne, both of Calif.

[73] Assignee: CBF Systems lnc., Covina, Calif.

[22] Filed: Dec. 10, 1973 [21] Appl. No.: 423,082

Primary Examiner-Samuel Feinberg Assistant E.taminerC. T. Jordan Attorney, Agent, or Firm-Heilman, Heilman &

Casella L- DC, POWER SUPPLY I 3% PULSE GEN ClQCUIT I l l l Jlll 1 1 July 1, 1975 [57] ABSTRACT A control and indicating circuit for use with squib operated explosive units. The squib filaments are each connected in series with a relay winding and a small current applied to the circuit. This current operates the relay but does not explode the squib. Relay lamps connected to relay contacts are lighted when the relay is operated, indicating that the circuit and squibs are ready. In order to fire the squibs, an alarm circuit applies the charge on a capacitor to the squib filaments. melting them and exploding the powder surrounding the filaments. After this operation, the circuit applies a pulsed current to the lamps. causing them to light intermittently, thereby indicating the end of the operation. The pulsed current is also applied to the indicating lamps whenever any one of the squib supply lines is opened, as for example, when a line is inadvertently cut.

11 Claims, 2 Drawing Figures I SQUIB CONTROL CIRCUIT BACKGROUND OF THE INVENTION Squib control circuits are old in the art and electric lamps have been used to indicate when the squib filament is conducting and ready for firing. However, in prior arrangements, the indicating lamps went out after the filaments were fired and there was no positive assurance that the squib filaments were melted. The circuit to be described hereinafter produces a pulsating current when the filaments are destroyed and this current is applied to the indicating lamps causing them to blink. This signal gives a positive indication that the squibs have been operated or the squib circuit has been opened. Also, a supervision circuit is arranged to show when all the relays are working and in their operative condition.

The control circuit can be used to operate squibs to open release valves on containers which store fire fighting fluids. The circuit can also be used to explode charges of dynamite in quarries and underground locations.

SUMMARY OF THE INVENTION The invention comprises a source of direct current power which may be applied to one or more squibs for actuating valves or exploding charges. A chargeable storage capacitor is connected in series with normally open relay contacts for providing the current to disrupt the squib filaments and generate heat necessary for the explosive action. A lamp relay is associated with each squib unit and the relay winding is connected in series withe the squib filament. When the relay is operated, an indicating lamp is lighted, showing that the circuit is ready for action. The firing action is controlled by an alarm circuit which may be actuated by a manually operated switch or by an automatic alann means. The alarm circuit operates an alarm control relay which connects a storage capacitor to all the filaments to melt them. After firing, each squib relay is normalized and a pulsating current from a multivibrator generator is connected to the signal lamps to produce a blinking light.

Additional details of the invention will be disclosed in the following description, taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURE FIG. 1 is a schematic diagram of connections of the main control circuit.

FIG. 2 is a schematic diagram of connections of an auxiliary circuit for connection to the main circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the circuit includes a source of direct current power 20, shown within dotted lines, a pulse generating circuit 21, also shown within dotted lines, and a relay control circuit. The relay control circuit includes a firing relay 22, four

lamp relays

23, 24, 25. and 26, and four resistors 27. 28, 29, and representing the squib filaments. The squibs in this case are any explosive containers which include resistive filaments surrounded by explosive charges. When the filament is heated by the passage of current. the charge explodes and creates a substantial pressure wave which LII can be used to operate valves, explode larger charges, or move pistons for other results.

The direct current power supply 20 includes a pair of terminals 31 for connection to a supply of alternating current power. A transformer 33 reduces the voltage to a predetermined value and applies it to a rectifier bridge 34 which produces direct current power having a predetermined output voltage (for example. 24 volts). This voltage is applied over positive conductor 35 and negative conductor 36 in series with relay contacts 37. The presence of this voltage, derived from the AC power lines is indicated by a pilot lamp 32, connected across the bridge terminals in series with

relay contacts

37 and 41. Terminals 31 are also connected to the winding 38 of a relay which operates the relay contacts to a position as shown in the drawing. If, for any reason, the alternating power should fail or be disconnected, relay 38 then receives no current, contacts 37 are opened and

contacts

40 and 41 are closed. This action transfers the

power lines

35, 36 to terminals 42 which are to be connected to a standby battery (not shown) having a voltage substantially equal to the voltage supplied by bridge 34. When the standby battery is connected, pilot lamp 43 is lighted.

The pulse generating circuit 21 comprises a free running multivibrator circuit including transistors 44 and 45, this type of pulse generating circuit being generally well known. The frequency of pulses is adjusted by varying the values of the capacitors 46 and 47. The frequency output of this circuit is not critical and may vary from two per second to eight per second. The output from the multivibrator is applied to a first transistor amplifier 48 and then to a second transistor amplifier 50, after which it is connected to a pulse output conductor 51. The pulse shape of the output wave is shown in circle 52. Output conductor 51 is connected to a contact 66 on all four of the lamp relays.

The firing relay 22 has its winding connected to

terminals

9, 10 on terminal strip 53, these terminals being connected to the alarm circuit which may include a source of electric current 54 and a switch 55. The latter may be operatively associated with conventional temperature sensing means (not shown), whereby said switch may be operated automatically upon actuation of said temperature sensitive means. A separate battery is not necessary as terminal 14 may be connected to the positive conductor 35 and the power supply 20 used instead. The

firing relay contacts

56, 57 are connected to the four

squib resistors

27, 28, 29, and 30 in series with diodes 58, the other side of the contacts 65 being connected to the negative side of a storage capacitor 60. This capacitor 60 has its positive side connected to the 24 volt supply line, and charges relatively slowly since its direct current supply is in series with the resistance of the rectifier bridge 34 and the secondary winding of transformer 33. When the capacitor 60 is fully charged, it is ready to apply its full quantity of electricity fo the squib resistors to heat them to incandescence.

Lamp relays

23, 24, 25, and 26 are each coupled to an indicator lamp 62 which burns steadily when the squib resistors are conductive but blinks intermittently after the resistors have been destroyed. It should be noted that under normal conditions, all four lamp relay windings take current and remain in their operating condition as shown in the figure. As an example. the current which operates relay 23 can be traced from the positive conductor 35, over conductor 63, through winding 23, over conductor 64, then through squib resistor 27, to the negative conductor 36. At the same time, lamp 62 is lighted by current from conductor 35, through the lamp 62, then through contacts 65, and to the negative conductor 36. All four lamp relays have the same type of operating circuits.

When the winding 22 of the firing relay receives cur rent from the closing of the alarm switch 55,

contacts

56 and 57 are closed and operating current flows from the upper side of storage capacitor 60 through the contacts, then through diodes 58 and conductors 64, to terminals 1, 3, 5, and 7, and through the

resistors

27, 28, 29, and 30, heating them to incandescence, exploding the charge and disrupting the resistors. After the firing act, there can be no current through the resistors and the lamp relay windings receive no current, permit ting their armatures to spring back to their normal position, opening contacts 65 and closing contacts 66. This action connects all the lamps 62 to conductor 51 and the pulse generator 21. As a result, the lamps blink instead of burning steadily.

Another indicating circuit is provided by connecting contacts 67, on each lamp relay in series with each other and terminals 11 and l2. A source of potential 68 and an indicating means 70 can be connected to terminals l1 and 12 and, prior to firing a lighted lamp 70 indicates that all the lamp relays are in their actuated condition. Still another indicating lamp 71 can be used to monitor the operation of the pulse generating circuit 2!. If lamp 7i blinks at the proper frequency, it indicates that the generating circuit is operating satisfactorily.

Lamps 62 produce a steady light prior to firing and a pulsating light after firing, thereby indicating normal operation. If any one or all of the lamps show a pulsating light before firing, it indicates that the associated relay is not functioning properly or that the squib resis tor is open and will not fire.

The circuit shown in FIG. 1 is arranged for firing four squib resistors. When more than four are to be controlled, an auxilliary circuit, shown in FlG. 2 is used. This circuit has many of the components used in HQ 1 but contains no power supply and no pulse generating circuit. The auxiliary circuit uses the power supplies in the main circuit. these supply circuits connected to the auxiliary circuit by means of

conductors

72, 73, and 74 connected to terminals l3, l4, and 15. Conductor 72 is to be connected to terminal 13 on the main circiut and supplies pulsating current from line 51 and circuit 21 to contacts 66 and lamps 62 in the auxiliary circuit.

Conductor 73 is to be connected to terminal 14 on the main circuit (FIG. 1) and supplies direct current power of 24 volts from

lines

63 and 35. This power charges capacitor 60, operates the auxiliary relay 22 to fire the squibs and also powers the four relays, 23, 24, 25, and 26. Conductor 74 is to be connected to terminal on the main circuit. This is the ground return and the negative conductor for the 24 volt power.

It has been found that at least 10 auxiliary circuits can be added to the system using only one main circuit with a 24 volt power supply and a pulse generating circuit 21. This series of connections adds up to 40 additional squib control units, each circuit with its own indicating lamps and firing contacts. Again, it should be noted that battery 68 can be eliminated. if desired, by connecting the right hand terminal of lamp 70 to the positive terminal 14 and then connecting terminal ll to terminal 15. In a similar manner, the upper terminal of switch 55 can be connected to terminal 14, and terminal 9 connected to terminal 15, thereby eliminating battery 54.

The embodiments of the invention, in which an exclusive property or privilege is claimed, are defined as follows:

1. A squib control and indicating means for indicating the condition of a squib filament by means of an indicating lamp before and after firing comprising:

a. a source of direct current power;

b. a source of pulsating current;

c. a lamp relay including a winding connected in series between the source of direct current and the squib filament for activating the relay, said relay also including a pair of contacts connected in series between the source of direct current and the indicating lamp for lighting the lamp whenever the relay is actuated;

d. means for firing the squib filament; and

e. means for indicating when the squib filament has been fired, including a pair of relay contacts on said lamp relay connected between the lamp and said source of pulsating current.

2. A squib control means as claimed in claim I wherein said source of pulsating current includes a free running multivibrator circuit.

3. A squib control means as claimed in claim 1 wherein said relay contacts include a single pole double throw switching means, the common contact connected directly to one side of the indicating lamp.

4. A squib control means as claimed in claim I wherein said means for firing the squib filament includes a chargeable capacitor and a firing relay including a pair of contacts connected between the capacitor and the squib filament.

5. A squib control means as claimed in claim 1 wherein the source of pulsating current has a frequency of less than ten cycles per second.

6. A squib control means as claimed in claim 4 wherein said firing relay includes a winding connected to a source of electric power and a switch.

7. A squib control means as claimed in claim 6 wherein said switch is operated automatically by a tem perature sensitive means.

8. A squib control means as claimed in claim 4 wherein said chargeable capacitor is charged by the source of direct current power.

9. A squib control means as claimed in claim 1 wherein a plurality of squib filaments are provided, each squib filament being associated with a lamp relay including a winding connected in series with the source of direct current and the squib filament.

10. A squib control means as in claim 9 further including auxiliary circuit means for connecting additional squib filaments to the squib control and indicating means.

ll. A squib control means as claimed in claim l wherein said source of direct current power includes a main source of power derived from alternating current and a standby battery coupled to the control means through a relay which is operated when the main source of power is disconnected.

Claims

1. A squib control and indicating means for indicating the condition of a squib filament by means of an indicating lamp before and afTer firing comprising: a. a source of direct current power; b. a source of pulsating current; c. a lamp relay including a winding connected in series between the source of direct current and the squib filament for activating the relay, said relay also including a pair of contacts connected in series between the source of direct current and the indicating lamp for lighting the lamp whenever the relay is actuated; d. means for firing the squib filament; and e. means for indicating when the squib filament has been fired, including a pair of relay contacts on said lamp relay connected between the lamp and said source of pulsating current.

2. A squib control means as claimed in claim 1 wherein said source of pulsating current includes a free running multivibrator circuit.

4. A squib control means as claimed in claim 1 wherein said means for firing the squib filament includes a chargeable capacitor and a firing relay including a pair of contacts connected between the capacitor and the squib filament.

7. A squib control means as claimed in claim 6 wherein said switch is operated automatically by a temperature sensitive means.

11. A squib control means as claimed in claim 1 wherein said source of direct current power includes a main source of power derived from alternating current and a standby battery coupled to the control means through a relay which is operated when the main source of power is disconnected.