US3075125A - Exploders - Google Patents

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Publication number
US3075125A
US3075125A US33832A US3383260A US3075125A US 3075125 A US3075125 A US 3075125A US 33832 A US33832 A US 33832A US 3383260 A US3383260 A US 3383260A US 3075125 A US3075125 A US 3075125A
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US
United States
Prior art keywords
voltage
output
current
transistor
resistor
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US33832A
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English (en)
Inventor
Mcauslan James Hay Loudon
Nock William
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
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Publication of US3075125A publication Critical patent/US3075125A/en
Anticipated expiration legal-status Critical
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/04—Arrangements for ignition
    • F42D1/045—Arrangements for electric ignition
    • F42D1/05—Electric circuits for blasting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • F42B3/10—Initiators therefor

Definitions

  • the initial voltage across sthe circuit and current through the firing circuit must be much higher than the mean voltage and current values.
  • the hazard during the early part of the delivery period is greater than it would be if the firing current and voltage were maintained at the mean values, since the energy ,dissipated into a fault, such as a -break of circuit or a shortcircuit, increases with increase in the current and voltage prevailing at the time of fault. If the energy output could be maintained at the mean amplitude for the full application time, the total energy delivered would be the same but the hazard would be reduced for a given energy output. This may be achieved by employing an assembly that produces a square wave energy output i.e. one in which the voltage and current rise abruptly to constant amplitudes and fall abruptly again after a period of time.
  • the object yof .the present invention is to provide exploders which when used to tire electric detonators in coal mines will be inherently safer than exploders used hitherto, and which, at the same time, may be produced at a reasonable cost.
  • an exploder for liring electric detonators and the like includes in circuit with a source of electrical energy one or more solid semiconductors arranged to control electrical characteristics ofthe output energy so that the values of these characteristics are maintained within predetermined limits such as to render the tiring of electric detonators in fredamp atmospheres by the said exploder safer than it would be if the circuit of the exploder did not include the said solid semi-conductors.
  • the source of electrical energy is conveniently a dry ybattery and although the battery may be used to supply the output energy directly it is preferred that the energy to the output terminals should be provided by the discharge from -a capacitor which has been previously charged from a dry batteryor other convenient sourceV of ,electricity.
  • the duration ofthe application of the output energy is controlled tsoiihat the required energy is passed through the detonator circuit before any appreciable movement of the rock burden can take place and consequently breaks in the circuit caused by rock 'movement are prevented from occurring while energy is passing through the circuit.
  • the vduration of the output energy it is preferred to control the vduration of the output energy to less than 4 milliseconds by including in the exploder a mechanical or electrical time switch.
  • the time of energy application may arranging for the output energy to be by-passed after the desired time through a transistor which is connected to a capacitor and arranged lto conduct when the capacitor becomes charged to a certain value through a resistance.
  • the timing circuit is arranged so that the charging of the capacitor commences simultaneously with the initial application of the output energy and the time when the condenser will be charged the transistor to conduct can be pre-determined by adjustment of the resistance in circuit with the capacitor.
  • the electrical characteristics of the output energy which are controlled by the solid semi-conductors are voltage and current. If the resistance of the tiring circuit remains constant the voltage is proportional to the current so that enr/5,125
  • the solid semi-conductor in the form of a controlling transistor may be connected in series with the output terminals so that the output current passes through the transistor to output terminals or it may be connected in parallel across the output lterminals so that all current in excess o' that desired is bypassed therethrough.
  • the controlling transistor connected in parallel, i.e. shunt connected with the output terminals, since in the event of failure. of the said transistor, which usually results in a v.short circuit' formingacross it, all the energy will Vllow through the transistor circuit and no energy will flow through the output ⁇ terminals.
  • the detonators will in this case ⁇ fail to fire Whereas with a series connected transistor failure of the controlling transistor could result in an excessive current ow.
  • the maximum energy of any spark resulting from any short circuit will be limited.
  • the inclusion of a time switch to limit the time of application of the output energy -to ensure that the energy tlow is nished before breaks in the circuit due to rock movement can occur, is also desirable to enhance the safety of the current controlled exploder.
  • Using the timing ⁇ device and controlling the current to a substantially constant value the current and voltage of the output energy have desirable substantially square wave patterns.
  • This device is conveniently a voltage regulating diode, which may conveniently be a solid semi-conducting diode.
  • a form of exploder in accordance with the invention in which the voltage of the output energy is controlled includes a semi-conducting voltage regulating device shunt connected to the output terminals.
  • This device is conveniently a silicon voltage regulating diode.
  • a timing circuit in order to safeguard against excessive current in the event of a fault or short circuit in the output circuit it is preferredto include a high resistance in series with the output terminals.
  • FIG. 1 shows the schematic diagram of a circuit making use of a shunt-type current regulator and incorporating an output voltage limiting device and an arrangement to cut off the output after a pre-determined time.
  • FIG. ⁇ 2 schematically illustrates another embodiment ⁇ of the invention.
  • a suitable source ofelectrical energy which can be fsmallbatteries of the hearing-aid type, is connected between theV terminals 1 and 2 with the terminal'l positive.
  • the storage capacitor 3 is then charged to the voltage of the lsource of electrical energy.
  • the switch 4 may be operated and the storage capacitor 3 discharged into the transistor controllingoircuit [and the output load.
  • the control transistor-'5, which is of the n-p-n junction type, is connected with itscollector toa resistor 6 ⁇ and its emitter to a resistor 7, the other ends of these resistors being connected to the storage capacitor 3 when -it is being discharged.
  • An output is taken between the emitter and collec-tor of the control transistor through the reference-resistor S to the output terminals 9 and 1).
  • a voltage regulating semiconductor diode 11, which maintains a constant voltage drop across itself over a w-ide range of currents is arranged with its negative terminal connected to the negative end of the reference resistor 8.
  • An amplifying transsistor 12 which is of the p-n-p type, is arranged with its emitter connected to the positive end of the reference resistor 3, its hase to the positive end of the vol-tage regulating semi-conductor diode 11 and its collector to the base of the control transistor S. lf the voltage drop across the reference resistor S is greater than the voltage of the voltage regulating semi-conductor diode 11, then base current will flow in the amplifying transistor 12 causing an ampliilcd current to iiow in its collector and in the base of the control transistor 5.
  • the timing circuit comprises the voltage regulating semiconductor diodes 11 and 14, together with their feed resistor 15 a resistance-capacitance timing circuit comprising the timing resistor 17 and the timing capacitor 16, and the switching transistor 1S.
  • the current regulating action quickly adjusts circuit conditions and a certain voltage is developed across the series combination comprising the resistor 15 and the voltage regulating semi-conductor diodes 14 and 11.
  • the action of the voltage regulating semi-conductor diodes is to produce across each of them a lixed voltage drop which is maintained substantially constant while the storage capacitor 3discharges.
  • the switching transistor 13 is connected with its emitter to the junction of the voltage regulating semi-conductor diodes 11 and 14, its base to the junction between the timing resistor 17 and the timing capacitor 16, and its' collector to the base of the control transistor 5L Initially, the timing capacitor 16 is discharged, so that the base ofthe switching transistor' 18 is positivewith respect to its emitter. VUnder these conditions, the switching transistor 18 is maintained in the cut-oit condition and no collector current ows.
  • the timing capacitor 16 will immediately commence to charge through the timing resistor 17 and ⁇ when the potential across the timing capacitor 16 is such that the base t of the switching transistor 18 becomes negative with re-l spect to its emitter, then the switching transistor 18 will ⁇ V pass collector current which will increase the base current ofthe control transistor 5 and cause lthis transistor to become fully conducting, thus reducing the output to zero.
  • the capacitor 19 is included so that the control tran-V ⁇ sistor 5 is supplied with a very heavy base current during the ytime immediately lfollowing the switching action of switch 4 in order to makel the control transistor 5 con-- duct very quickly and prevent the initial output current exceeding the desired value.
  • a voltage 'regulating semi-conductor diode 20 is fitted to limit the maximum voltage. So long as the voltage ap- Y pearing between terminals9 and 10 under normal operationis'less than the operating voltage of the voltage regulating semi-conductor diode 20, the said diode will not by-pass any of the output current. If this voltage is exceeded, however, the voltage regulating semi-conductor diode will by-pass current and prevent the voltage rising above the pre-determined value.
  • the voltage between the collector and base of the control transistor 5 is related to the output voltage.
  • the voltage regulating semi-conducting diode 29 may be interposed in this position. In this case, however, it must have an operating voltage which exceeds the prescribed maximum output voltage by the magnitude of the voltage drop across the reference resistor 8.
  • a voltage regulating semi-conductor diode in this position will pass current to the base of the control transistor 5 and result in an amplified collector current in this transistor which will prevent any further rise in the output voltage.
  • An alternative form of voltage limiting device which can be used in either of the positions described is a p-n-p-n semi-conductor switching diode.
  • This device has the property that provided the voltage across it does not reach a critical level ,the diode does not conduct, but when this level is exceeded a rapid switching action takes place and the voltage across the device drops to Va fraction of a volt.
  • the output voltage developed between the output terminals 9 and 10 rises above the pre-determined value the device becomes conducting and reduces the output voltage substantially to zero.
  • the magnitudes of the voltage of the electrical energy source and the capacitance of the storage capacitor 3 are a compromise between the requirementsthat the voltage v of the electrical energy source should be fairly high, since the energy stored by the storage capacitor 3 will be in proportion to v2 and that the change in voltage as the capacitor discharges during the time that the exploder is delivering current should be small in order to reduce the regulating action required of the system.
  • a particular exploder required to deliver a current of 1.35 amps. into output circuit resistances up to 33 ohms for a period of 4 milliseconds, it was found that a 100 volt battery was a suitable energy source when the storage capacitor 3 had a value of 500 microfarads.
  • the value of the reference resistor S can be calculated from the operating voltage of the voltage regulating semi-conductor diode l1 and the value of current required.
  • the voltage regulating semi-conductor diode 11 has a nominal operating voltage ot' 6.2 volts and the reference resistor 8 is adjusted to a value a little below 5 ohms.
  • the maximum value of the timing resistor 17 is, however, limited by the necessity of passing suiicient current to the base of switching transistor 18 in order to make transistor 5 fully conducting.
  • the value of the timing capacitor 16 is 5 microfarads and the timing resistor 17 is adjusted to a value a little below l kilohm.
  • FIGURE 2 shows the schematic diagram of a circuit incorporating a shunt voltage regulator and a mechanical time switch.
  • the source of electrical energy which may be in the form of a battery of the hearing-aid type, is applied to the input terminals 21 and 22.
  • the switch 24 With the switch 24 in the position shown the storage capacitor 23 will be charged to the voltage of the electrical energy source.
  • the switch 24 When the switch 24 is operated the said capacitor will be discharged into the output circuit.
  • a mechanical timing switch 25 is incorporated in the output circuit and is usually operated simultaneously with the switch 24.
  • voltage regulating semi-conductor diode 26 is connected directly across the output terminals 27 and 28 and to the storage capacitor 23, during its discharge, by the load resistor 29. If the output circuit resistance between the output terminals 27 and 28 is sutiiciently large the voltage across the output will rise as soon as the capacitor 23 is connected to the regulating circuit until the voltage regulating diode 26 commences to conduct. Sutlicient current will then be diverted through the voltage regulating semi-conductor diode 26 to produce a voltage drop across resistor 29 such as to maintain the voltage between the output terminals 27 and 28 at the pre-determined maximum value.
  • the time switch 2S will open disconnecting the storage capacitor 23 from the output circuit.
  • the simple voltage regulating semiconductor diode 26 one or more transistors.
  • the magnitude of the storage capacitor 23, the voltage of the energy source and the value of load resistor 29 should be chosen such that for the particular resistance used in the external circuit the voltage across the output terminals 27 and 28 should not be less than the limiting voltage of the regulating semi-conductor diode 26, at the end of the pre-determined energy application time.
  • the value of the load resistor 29 must also be chosen so as to limit the peak current to a safe magnitude when the capacitor 23 is first switched to the discharge position.
  • Circuits incorporating solid semi-conductor devices to limit the current and voltage in the manner described and illustrated may be assembled in a compact form in the normal type of casing used for exploders and the exploders incorporating such circuits may optionally also include testing devices, safety switches and the like.
  • An exploder for tiring electric detonators and the like which comprises in combination, a pair of output terminals, a source of electrical energy having two pole pieces at different electrical potential, one of the said pole pieces being coupled to one of the said output terminals, two resistors, one of which is a ballast resistor and the other a reference resistor, electrically connected at a junction, the other end of the ballast resistor being connected to the other pole piece and the other end of the reference resistor being also connected to the said other output terminal, at least one control transistor having a r base electrode and two other electrodes, and a constant voltage device having two electrical leads, one of the said leads being coupled to the base electrode of the said transistor and the other being coupled to the said other output terminal, one of the two other electrodes of the transistor being coupled to the said junction between the said two resistors and the other being coupled to the said one output terminal, the resistance of sa-id ballast resistor being chosen in accordance with the characteristics of the said control transistor, the potential difference between the said pole pieces, the
  • saidl voltage limiting means includes a voltage regulating semi-conductor diode.
  • Timing switch includes a capacitor-resistor timing circuit and a switching transistor controlled by the timing circuit to bypass Said output energy after a desired time interval.
  • yAn exploder as in claim 10 and further including an amplifying transistor having a base electrode and two kother electrodes, the base of said amplifying transistor being connected to the lead of the said constant voltage device remote from said other output terminal, one of the other 4electrodes of said amplifying transistor being con'- nected to the base electrode of the said control transistor, and the remaining electrode being connected to the said junction of said two resistors.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
  • Air Bags (AREA)
  • Generation Of Surge Voltage And Current (AREA)
US33832A 1959-06-03 1960-06-03 Exploders Expired - Lifetime US3075125A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB18937/59A GB890146A (en) 1959-06-03 1959-06-03 Improvements in exploders

Publications (1)

Publication Number Publication Date
US3075125A true US3075125A (en) 1963-01-22

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Application Number Title Priority Date Filing Date
US33832A Expired - Lifetime US3075125A (en) 1959-06-03 1960-06-03 Exploders

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US (1) US3075125A (de)
AT (1) AT221650B (de)
BE (1) BE589079A (de)
DE (1) DE1211096B (de)
FR (1) FR1265998A (de)
GB (1) GB890146A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3448339A (en) * 1966-05-13 1969-06-03 Lockheed Aircraft Corp Stored electrical energy circuit with safety interlocks
US4106073A (en) * 1973-10-24 1978-08-08 Hedberg John Bengt Goran Apparatus for igniting the match heads of electric detonators
CN113911301A (zh) * 2021-11-23 2022-01-11 中国航空工业集团公司洛阳电光设备研究所 一种引爆装置

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE416349B (sv) * 1976-05-18 1980-12-15 Nitro Nobel Ab Metod och anordning for initiering av elektriska sprengkapslar
US4452685A (en) * 1983-05-02 1984-06-05 Olin Corporation Electrodes for electrolytic cells
US4882993A (en) * 1988-08-05 1989-11-28 The United States Of America As Represented By The Secretary Of The Army Electronic back-up safety mechanism for hand-emplaced land mines

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2751550A (en) * 1953-10-12 1956-06-19 Bell Telephone Labor Inc Current supply apparatus
US2832900A (en) * 1957-02-12 1958-04-29 Gerald M Ford Transient overvoltage and short circuit protective network
US2837663A (en) * 1956-05-16 1958-06-03 Gen Dynamics Corp Monostable trigger circuit
US2903625A (en) * 1955-02-19 1959-09-08 Wasagchemie Ag Capacitor blasting detonating machine
US2906941A (en) * 1958-06-10 1959-09-29 Bell Telephone Labor Inc Current supply apparatus
US2961583A (en) * 1957-07-05 1960-11-22 Femco Inc Detonator circuit for permissive explosion shot firer

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE17942C (de) * F. KROEHL in Allstedt Kühlapparat für Brennereimaische und andere Flüssigkeiten
DE15954C (de) * F. M. STEVENS in Boston Neuerungen an Dampfentwicklern
FR1002808A (fr) * 1949-12-14 1952-03-11 Mivica Fusée à temps pour bombes d'avions et projectiles similaires

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2751550A (en) * 1953-10-12 1956-06-19 Bell Telephone Labor Inc Current supply apparatus
US2903625A (en) * 1955-02-19 1959-09-08 Wasagchemie Ag Capacitor blasting detonating machine
US2837663A (en) * 1956-05-16 1958-06-03 Gen Dynamics Corp Monostable trigger circuit
US2832900A (en) * 1957-02-12 1958-04-29 Gerald M Ford Transient overvoltage and short circuit protective network
US2961583A (en) * 1957-07-05 1960-11-22 Femco Inc Detonator circuit for permissive explosion shot firer
US2906941A (en) * 1958-06-10 1959-09-29 Bell Telephone Labor Inc Current supply apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3448339A (en) * 1966-05-13 1969-06-03 Lockheed Aircraft Corp Stored electrical energy circuit with safety interlocks
US4106073A (en) * 1973-10-24 1978-08-08 Hedberg John Bengt Goran Apparatus for igniting the match heads of electric detonators
CN113911301A (zh) * 2021-11-23 2022-01-11 中国航空工业集团公司洛阳电光设备研究所 一种引爆装置
CN113911301B (zh) * 2021-11-23 2023-02-21 中国航空工业集团公司洛阳电光设备研究所 一种引爆装置

Also Published As

Publication number Publication date
AT221650B (de) 1962-06-12
FR1265998A (fr) 1961-07-07
GB890146A (en) 1962-02-28
BE589079A (fr) 1960-09-26
DE1211096B (de) 1966-02-17

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