US2481231A - Safety device for setting off explosive charges - Google Patents

Description

Sept. 5, 1949.

SAFETY DEVICE R. G. MARTIN FOR SETTING OFF EXPLOSIVE CHARGES Filed Sept. 19, 1947 Patented Sept. 6, 1949 SAFETY DEVICE FOR' SETTING. OFF

EXPISOSIVE cannons Russell, G., Martin, Russcllvillc, Va. Application September 19, 1947 Serial 174,924 3 Claims. (01. 175-115).

This inventionrelates: toiignition devices for explosives andrmore; particularly to. a pportable ignition: device. for use; inlmines, and the like tor setting off explosive charges;

A main object: of'the invention-is. torprovide a noveluandiimproved safety device for setting. oi charges of explosive which isvery simpl'e inxcon strnction compact in size, andlreliable inopera tion A further: objector; the invention is to provideanimproved safety devicerfor' use in-mining operations; and the. like, in setting oi-i' explosive chargesr said. device containing the source of current:v for-igniting the. explosivev and being ar= ranged so: that the, explosive cannot accidentally be. set .ofiifwhile; the-wiring connections thereof are beingzm-ad'e: to the: device, thereby reducing hazards to miners, andlat the same time, providing effective control of the ignition of the'explosi ve;

Further objects and advantages :of the invention. will: become apparent from: the following description and* claims; and from the accom panyin'g. drawings, wherein:

Figure 1 is an elevational view showingasafety explosive ignition device constructed in accordance with the present invention, the hinged cover of the device being shown in open position.

Figure. 2 is atop view of the ignition device of Figure 1 with the cover in closed position.

Figure 3 is an enlarged cross-sectional detail view taken"on-line3'-3' of Figure 1.

Referring to the drawings; tldesignates-agen orally rectangularhousing, preferably of insulatin-g, material; provided, with a; cover 6 2, hinged -to the housing at l3, l3. Received in the housing ii are a pair of flashlight battery cells it and i5, cell l being inverted, as shown in Figure l. Secured to the bottom wall of housing I i beneath the cells I4 and I5 is a U-shaped contact spring I6 which engages the bottom of the metal casing of cell [4 at one arm thereof and engages the center positive pole contact of the inverted cell l5 at the other arm thereof.

The top wall of housing I l is apertured immediately above the center positive pole contact of the cell l5 and secured to said top wall around the aperture therein is a metal washer ll. Passing slidably through the washer is the shank of a headed bolt or pin is to the bottom end or which is secured a collar member l9, preventing upward removal of the bolt l8 from the washer H. A coiled spring 29 encircles the shank of bolt l8 and bears between the head of the bolt and washer ll, thereby biasing the bolt upwardly. When bolt is is manually depressed, the bottom notches 30 and end thereof engages the center positive pole con? tact of cell Mi Secured to the top wall of housing H by a: bolt 2i isanangle bracket 22, and pivotally secured to the upstanding arm of bracket 22 is a lever bar 23 which is swingable in a transverse verticalplane of housing H. The angle bracket 22 is locatedv adjacent'the front edge of said top wall, and secured to saidtop wall adjacent its rearedge is a second angle bracket 24. Pivotally secured to, the upstanding arm. of bracket 24 is a lever bar 25' which is swingable in, the same transverse vertical plane as lever: bar 23. Secured to the top wall of housing H between the angle brackets til-and 24 is an upstanding boss26 of insulating material, and secured to, the top of. said'boss in th transverse plane of lever arms, 2'3. and; 25 is a metal bar 2], the ends or said bar 2i being normally spaced from the lever bars 23' and 25.,by the biasing action of respective coiled springs 28 and 23- which bear between suitable recesses formed in boss 25 and the adjacent inner edge portions of the respective lever bars 23 and 25. The bottom ends of the lever bars bear against the top wall of the housing, thereby limiting outward rotation of the lever bars under the biasing force exerted thereon by the springs 28 and 29. The upper portionsof the outer edges of the lever bars 23 and 25 are formed with respective arcuate 3|- providing finger engaging means for rotating the lever bars inwardly. By exerting squeezing pressure on said lever bars with the fingers, the lever bars are simultaneously brought into'contact with the ends of the bar 21.

Secured to the bottom surface of the housing top wall by bolt 2| is a bowed contact spring 32 which engages the bottom of the metal casing of the inverted cell It. Secured to the top wall of the housing H between washer I1 and boss 26 is a transverse terminal block 33 of insulating material provided with spaced terminal jacks 34 and 35. Washer I! is connected to terminal jack 34 by a wire 36 and bracket 25 is connected to terminal jack 35 by a wire 31. The external ignition element, not shown, is connected to the jacks 34 and 35 by wires 38 and 39 provided with male prongs which are plugged into the respective jacks.

When the charge of explosive is to be detonated, lever arms and 3| are squeezed together with the fingers so that they engage the ends of bar 21, and the head of bolt I8 is pushed downwardly so that its bottom end engages the center positive terminal of cell [4. This completes the detonating circuit, said circuit comprising wire 38, jack 34, wire 36, washer l7, bolt l8, cell l4, spring I 6, cell l5, contact spring 32, bolt 2 I, bracket 22, lever arm 23, bar 21, lever arm 25, bracket 24, wire 37, jack 35, and wire 39.

It is to be noted that the detonating circuit is normally open at three points, namely, at lever arm 23, at lever arm 25 and at contact bolt is, so that accidental detonation cannot occur when the wires 38 and 39 are connected to the jacks 34 and 35.

The cover l 2 is normally secured in closed position by a hook latch 49 pivotally connected thereto which is engaged with a pin 4| projecting from the side wall of housing I l.

While a specific embodiment of an ignition device for setting ofi explosive charges has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. A portable shot firer comprising an insulated box-like casin having top and bottom Walls, a pair of vertically disposed dry battery cells arranged in inverted, side by side position in said casing and substantially filling the space between lower ends of said cells, a spring retracted plunger contactor mounted on and operating through said top wall, said contactor being arranged to engage the upper terminal of one of said cells when depressed, a pair of laterally spaced lever contactors pivotally mounted on said top wall to swing inwardly toward each other from outward starting poistions, a bridging block mounted on said top wall between said levers, spring means normally yieldably maintaining said levers in their outward tactors, a pair of jacks mounted on said top wall, and means severally connecting the remaining lever contactor and said plunger contactor with an electrical detonator concan be detonated only while said plunger contact is held in depressed position and both of said lever contactors are held inwardly against said bridging block.

2. A portable shot firer comprising an insulated battery case containing battery means having a. pair of terminals, 2. spring retracted plunger contactor on said case engageable only in its inpressed position with one of said terminals, a pair of lever contactors, means pivoting said levers for movement toward and away from said other, spring means normally maintaining said levers yieldably in spread relation, a bridging block on said case between said levers with which said levers are out of contact in their normal spread positions, means connecting one of said lever con- .tactors with the other terminal of said battery means, and a pair of jacks on said case severally connected to the remaining lever contactor and said plunger contactor, whereby an electrical detonator connected to said jacks can be detonated only while said plunger contact is held in in-pressed position, and both of said lever contactors are held in inward positions in engagement with said bridging block.

3. A shot firer comprising an insulated sup port, a spring retracted plunger contactor on said support, a contact with which said plunger conently swingable between their normal spread positions and their inwardly swung positions, a pair of jacks on said engagement with said bridging block.

RUSSELL G. MARTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date

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