US3704393A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitor discharge type blasting machines
Assignee: ETI EXPLOSIVES TECHNOLOGIES INTE
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Filing: 1971-12-30
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Granted: 1972-11-28
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Expires: 1991-12-30
Abstract
Abstract Capacitor discharge blasting machines for initiating electroexplosive devices, e.g., electric blasting caps which comprises in combination, means for supplying direct current at a controlled rate and at potentials above 1,500 volts, a nonelectrolytic capacitor capable of accumulating charges at potentials in excess of 1,500 volts and capable of withstanding repeated charge-discharge cycles, means for indicating that such capacitors are being charged, electronic firing switch and interlock means positioned between and communicating with said capacitor, and electronic firing switch means for delivering current from said capacitor to current output terminals and thence to an electric blasting cap firing circuit, and means for bleeding off unwanted or residual charges from the power supply and current-discharging means.
Inventors
- 👤 Frank J Digney Jr
- 👤 Earl M Phinney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:00
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/02; H03K3/53; H03K3/537; F; F42; F42D; F42D1/00; F42D1/04; F42D1/045; F42D1/05
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
131 words
A condenser-discharge blasting machine for initiating electro-explosive devices comprising, in combination, a. a nonelectrolytic main storage capacitor, including means for charging said capacitor to a potential in excess of 1,500 volts, said capacitor being capable of discharging currents in excess of 1,000 amperes, one side of said capacitor being connected directly to one of two energy-output terminals, b. an electronic firing switch as the sole means of circuit closure connecting the other side of said main storage capacitor to the second energy-output terminal, c. means for insuring that said electronic firing switch will discharge the main storage capacitor at a prescribed minimum voltage in excess of 1,500 volts, d. means for connecting said energy-output terminals to a circuit containing an electro-explosive device, and e. means for disarming the main storage capacitor.
Claim 2
Dependent Claim
131 words
A condenser-discharge blasting machine for initiating electro-explosive devices comprising, in combination, a. a nonelectrolytic main storage capacitor, including means for charging said capacitor to a potential in excess of 1,500 volts, said capacitor being capable of discharging currents in excess of 1,000 amperes, one side of said capacitor being connected directly to one of two energy-output terminals, b. an electronic firing switch as the sole means of circuit closure connecting the other side of said main storage capacitor to the second energy-output terminal, c. means for insuring that said electronic firing switch will discharge the main storage capacitor at a prescribed minimum voltage in excess of 1,500 volts, d. means for connecting said energy-output terminals to a circuit containing an electro-explosive device, and e. means for disarming the main storage capacitor.
Claim 3
Dependent Claim
21 words
An apparatus of claim 1 wherein means for charging said main storage capacitor is a hand-cranked alternator and a rectifier circuit.
Claim 4
Dependent Claim
51 words
The apparatus of claim 1 wherein the means for charging said main storage capacitor is a 110-440 volt AC power line connected through a normally open circuit closure control to the primary of a step-up transformer, the secondary of which is connected to the main storage capacitor through a rectifier circuit.
Claim 5
Dependent Claim
56 words
A blasting machine of claim 1 wherein the means for charging the main storage capacitor is a battery connected to an oscillator circuit through a normally open circuit closure control that supplies alternating current to the primary of a step-up transformer, the secondary of which is connected to the main storage capacitor through a rectifier circuit.
Claim 6
Dependent Claim
23 words
A blasting machine of claim 3 wherein the circuit closure controls are spaced at least 100 feet from the blasting machine energy-output terminals.
Claim 7
Dependent Claim
23 words
A blasting machine of claim 4 wherein the circuit closure controls are spaced at least 100 feet from the blasting machine energy-output terminals.
Claim 8
Dependent Claim
25 words
A blasting machine of claim 1 wherein the electronic firing switch comprises a two-element spaced arc gap enclosed within a casing containing an ionizable gas.
Claim 9
Dependent Claim
25 words
A blasting machine of claim 1 wherein said electronic firing switch is a triggerable three-element arc gap enclosed within a casing containing an ionizable gas.
Claim 10
Dependent Claim
216 words
A blasting machine of claim 8 in which the electronic firing switch has a main untriggered gap breakdown voltage which is substantially higher than the prescribed blasting machine firing voltage, and which can be triggered to fire with a main gap voltage substantially below the prescribed firing voltage, the input of said three-element arc gap being connected to one terminal of the main storage capacitor and the output of said three-element arc gap being connected to the first of two energy-output terminals and the other side of the main storage capacitor being connected directly to the second energy-output terminal, said electronic firing switch cooperating with (a) a pulse-triggering transformer the secondary of which is connected in series with a resistor between the input to the three-element arc gap and the triggering element of said three-element arc gap; (b) a pulse-shaping circuit comprising a resistor and capacitor in parallel, said pulse-shaping circuit connected in series with the primary of the pulse-triggering transformer and a two-element arc gap which series circuit is connected parallel to the main storage capacitor, said two-element arc gap having a gap spacing that insures conduction automatically when the main storage capacitor reaches the prescribed firing voltage thereby generating a trigger signal of suitable polarity and strength that renders the three-element arc gap conductive.
Claim 11
Dependent Claim
22 words
The blasting machine of claim 9 in which a normally open circuit closure device is connected in series with the pulse-triggering transformer.
Claim 12
Dependent Claim
19 words
The blasting machine of claim 10 in which a voltage limiting circuit is positioned across the main storage capacitor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-28 | 1976-05-29 | 1976-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-28 | 1980-05-29 | 1980-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-28 | 1984-05-29 | 1984-11-28 | $7700.00 | Window Closed / Lapsed |