US3044398A - Pressure-time responsive electronic firing device - Google Patents

Description

som :QE EE oom ooN 4 Sheets-Sheet 1 J. F. KEITHLEY ETAL July 17, 1962 PRESSURE-TIME RESPONSIVE ELECTRONIC FIRING DEVICE Filed D60. 50, 1949 A .UE

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PRESSURE-TIME RESPONSIVE ELECTRONIC FIRING DEVICE Filed Dec. so, 1949 4 sheets-sheet? FIG.2.

me/whom J. F. KEITHLEY M.L. SANDS 272mg M July 17, 1962 J. F. KEITHLEY ETAL 3,044,398

PRESSURE-TIME RESPONSIVE ELECTRONIC FIRINC DEVICE Filed DCC. 50, 1949 4 Sheets-Sheet 3 FIG. 3.

SWW/Mou J. F. KEITHLEY M. L. SANDS July 17`, 1962 .1. F. KEITHLEY ETAL 3,044,398

PEEssUREJrIME RESPONSIVE ELECTRONIC FIRING DEVICE Filed Dec. 50, 1949 4 Sheets-Sheet 4 ,l jfall" wl '53 I min-m2 1 I Y I 'L gmc/Maw J. F. KEITHLEY M. L. SANDS @www with iluid actuating means.

*Unitedl States vlate'nt C) 3,044,398 PRESSURE-TIME RESPONSIVE ELECTRONIC FIRING DEVICE Joseph F. Keithley, 920 Keystone Drive, Cleveland Heights, Ohio, and Matthew L. Sands, 11 Westgate Cambridge, Mass. Y Y Filed Dec. 30, 1949, Ser. No. 136,132

' 14 Claims. (Cl. 102-18) (Granted under Title 35, U.S. Code (1952), sec. 266) This invention relates to a pressure responsive device which is selectively responsive to a predetermined code of pressures by means of a time delay systemV cooperating Provision is made in this invention for accelerating the desired response when the pressure impulses received by the pressure responsive device are of such magnitude that rapid reaction of the device is desirable.

In accordance with this invention in 4its preferred form, a plurality of pressure operated mechanisms respond individually to predetermined pressure changes in a conducting uid medium to operate their respective electrical switches, thereby to cause an electrical system to integrate these varied responses until a certain predetermined controlling summation has been reached. This ultimate summation may then be utilized to cause the performance of any desired operation. Y Y

As an example of the application of this invention in its preferred form, the ultimate summation is used to explode a marine mine by means of a detonator which is connected to the electrical system.

A vessel cruising on a body of water causes the water under and near the vesselY to flow thereby producing a pressure change on the bedrof the body of water in accordance with Bernoullis theorem which states, that an increase in the rate of flow of a uid is accompanied by a reduction in the pressure thereof. Actual tests have shown that a positive pressure peak is formed in front of and under the bow of the moving vessel and that a negative pressure region is formed justaft of the bow to the stern. It has been discovered that the positive pressure peak is localized at the bow while the negative pressure region extends athwartships a distance of several beams and decreases in proportion to the distance athwartship. The pressure changes caused by la vessel rare known as the vessels signature and it is Vknown that the general pattern of the signature in constant for `varying speeds. The magnitudes of the pressures, which form a vessels signature, vary inversely as the square of the depth of water at which these pressures are received.

It, therefore, follows that a pressure responsive system will experience the maximum pressure changes when a vessel passes directly thereover. The preferred embodiment of the present invention is adapted to discriminate between these maximum pressure changes and pressure changes caused by distant ships, tides, waves, winds, and shallow draft Vessels which do not have the predetermined minimum vessel signature.

It is an object of this invention to provide la new and improved means which is responsive to a predetermined code of pressures.

Another object is the provision of a -new and improv means adapted to prepare an electrical circuit Vfor clos-V ing in response to a rst predetermined change in pressure and adapted to close said electrical circuit in response 3,044,39g Patented July l?, 1962Y ice to a second predetermined change in pressure of a predetermined magnitude 'and time duration.

Another object of this invention is to provide accelerating means for reducing the time duration Vrequired to close said electrical circuit when said second pressure change is of relatively large magnitude.

Another object is the provision of means for restoring the circuit to the normally unprepared condition in the event the second pressure change does not exist in suflicient magnitude for the required time duration.

Another object of the invention resides in the provision ofa new and improved mine firing control system which is adapted to become armed for a predetermined interval in response to a iirst predetermined pressure signal, and to be iired if a second predetermined signal is received during the predetermined interval; and in which means are provided for restoring the system to an initialror unarmed condition in the event the second signal is not received during the predetermined interval.

Another object of the invention is to provide a mine firing control system of the type hereinabove disclosed in which the sensitivity of the system is automatically adjusted in accordance with the depth of submergence of the mine.

Another object is to provide within a marine mine a new and improved fluid circuitv adapted to respond to changes in the pressure field adjacent the mine.

A further object resides in the provision of new and improved means for substantially filtering out or nullifying the effects of tides and waves upon the tiring mechanism of a pressure controlled marine mine.

An additional object lies in the provision of a new and improved mine which will not be subject to discharge by mine sweeping apparatus and countermining means.

A still further object lies in the provision of a new and improved mine tiring control system wherein the system operates tov detonate and explode the mine associated therewith in response to the movement of a surface vessel within the zone of destructivity of the mine.

Other objects and many of the attendant advantages of this invention will Vhe readily appreciated as the same becomes better understood by reference to the following detailed description whenconsidered with the accompanying drawings wherein:

FIG. 1 is a graph showing the pressure field caused by a moving vessel;

FIG. 2 is a diagrammatic view of the complete electrical and pressure system of thepressure-time responsive electronic device of the instant invention according to the preferred embodiment thereof;

FIG. 3 is a view in section of the pressure responsive apparatus of the instant invention, the switches and operating bellows therefor being shown in elevation;

FIG. 4 is a somewhat enlarged plan view of the switches and switch operating bellows as viewed from the bottom in FIG. 3; and j FIG. 5 is a sectional view of the switch operating bellows and switches taken on line 5--5 of FIG. 4.

Referring now more in detail to the drawings in which like reference characters refer to like parts throughout, the graph in FIG. 1 shows clearly the pressure changes Vcaused at various positions along a bed of water having a depth of 40 feet by a 6200 ton vessel traveling at l0 knots.

A positive pressure peak is evident at the bow and a nega.-r

tive pressure region is evident from aft of the bow to the stern. Sea waves have been recorded which have positive pressure magnitudes equal to a vessels positive pressure peak, but no waves have been recorded which have similar negative pressure regions of such long time duration as, for example, about 15 seconds as seen in FIG. 1. The preferred embodiment of the instant invention is specifically adapted to respond to pressure changes caused by vessels such as above described but may, of course, be modified to respond to various other conditions where a response to a different code of pressures is desired.

A pressure-time responsive electronic device for ring a mine is shown in FIG. 2 and FIG. 3 wherein a watertight mine casing 6 is shown having a bellows member 8 located at one end of the casing and exposed to sea pressure. Contained within bellows 8 is -a housing member having holes 9 located in the walls thereof and having a plate 16 mounted therein to divide said housing into a base pressure chamber 4 and a pressure change receiving chamber 7. The plate 16 has ya small pressure equalizing orice therein allowing restricted fluid communication between chambers 4 and 7.

On plate 16 in chamber 7 is mounted a calibrated depth compensating bellows 49 which has a switch supporting disc 20 mounted thereon. On the disc 20 are mounted the electrical switches A, B, C, D, E, F and G which are part of the electrical circuit to be described later. These switches may be of any suitable type such as, for example, microswitches. When the calibrated bellows 49 is cornpressed by sea pressure, which is transmitted to chamber 7 by way of holes 9 from bellows 8, the disc 20 is moved nearer the plate 16. rllhe distance disc 20 moves depends on the depth of water in which the mine is planted, thereby compensating for the reduction in amplitude of the vessels signature. A limiting screw 21 and a cooperating stopping block 24 are provided to limit the movement of the disc 20 at very large depths. The bellows 50-54 are calibrated and move the switch operating pins 60, 61, 62, 63 and 64, predetermined distances in accordance with the pressure changes affecting them. In FIG. 2 wherein it is assumed that the pressure in chamber 4 has been equalized through orice 15 with the pressure in chamber 7, the bellows 50-54 are in their normal positions.

The switch operating bellows 50 normally rests on switch A holding it open; but when the pressure in chamber 7 is increased by a positive pressure signal, the bellows 50 `is compressed, thereby exhausting air through vents 10 into chamber 4 and allowing the spring-biased switch A to close. As switch A closes, the condenser 65 is charged from battery 76, thereby placing the proper operating bias on the cathode of the cold cathode discharge tube or valve 75; and the RC circuit comprising condenser 65 and resistance 91 maintains this operating bias on the cathode of tube 75 for a predetermined time after switch A has opened.

A second electric gas discharge tube or valve 74 is electrically connected to switches B-G, and is caused to be opened a predetermined number of times bythe actuation of these switches. When the pressure in chamber 7 is decreased a predetermined amount, the bellows 51 is extended due to the greater pressure in chamber 4 which is in communication with the inside ofbellows 51 through Vents 11. The pin 61 upon moving away from plate 16 causes switches B and D to open and switch C to close. Switch C is located between the battery 77 and the control grid of the tube 74 and when closed causes tube 74 to lire. As the tube is fired, the charge transferring condenser 66 which is connected to the anode of Vtube 74 and which is normally charged from battery 77 through the current limiter resistance 97 and through normally closed switch D, discharges through the tube 74. An RC circuit which controls the time between successive firings of tube 74 comprises the condenser 66 and resistors 90, 92, 93 and 94 through which the condenser is selectively charged trom battery 77. The bellows 52, 53 and 54 having respective Vents 12, 13 and 14 and respective pins 62, 63 and 64 are calibrated to progressively close their respective switches E, F and G as the change in negative pressure becomes progressively greater in magnitude. This arrangement accelerates the ring of tube 74 when a pressure signal of known origin is received since switches E, F and G progressively remove resistances 92, 93 and 94 from the RC circuit, thereby allowing condenser 66 to charge more rapidly. When a suicient charge has been placed in condenser 66, tube 74 lires a second time.

A charge collecting condenser 67, which is normally discharged through resistances 95 and 96 sand closed switch B, collects Va charge from battery 77 through closed switch C and resistors 95 and 96 and establishes a potential on the control grid of tube 75. When tube 74 tires the second time before the voltage on condenser 65 has fallen below the operating Kbias of tube 75, the voltages of the condenser 67 and the cathode of tube 74 add to trigger tube 75 and cause current to ow therethrough from the condenser 96. The current responsive device and condenser 96 are connected in series with a current limiting resistance 99 and battery 77 This arrangement allows condenser 96 to receive energy from the battery 77 at a low current which is insuicient to activate the current responsive device 100. When the grid of tube 75 is properly biased, however, the current from the condenser 96' passes through tube 75 to the current responsive device which is arranged to cause the performance of any desired operation.

Although a marine mine detonator 100 has been chosen as the preferred embodiment of a current responsive device, it will be understood that this invention is not limited to this arrangement since the pressure-time responsive electronic device may be used to operate valves, gauges, and other current responsive devices which may be desirable in a hydraulic or pneumatic system.

Also any pressure responsive means such as diaphragms and the like may be used to transmit the changes in pressure to switch operating means without departing from the scope of this invention.

In explanation of an application of the instant invention, let it be assumed that a marine -mine is planted in a bed of water having a known depth `of 40 feet. The water pressure at this depth is transmitted from bellows 8 through holes 9 to chamber 7 where it causes bellows 49 to-draw disc 20 a predetermined distance toward plate 16. After a predetermined time of, for example, several hours, the pressures in chambers 4 and 7 are equalized through orifice 15 which places the pressure system of the mine in a readied condition to respond to a predetermined code of pressure signals.

Assume that a ship having the pressure signature shown in FIG. 1 passes directly over the mine thereby subjecting the instant invention to a positive pressure peak for about 5 seconds and a negative pressure region for about l5 seconds. Upon receipt of the positive pressure peak, bellows 50 compresses allowing switch A to spring closed and complete the circuit for charging condenser 65, thereby placing the proper operating bias on the cathode of the firing tube 75 for a predetermined time duration such as, for example, 45 seconds following the opening of switch A. Immediately following, ,the bellows 51 expands due to the negative pressure regionshown in FIG. 1, thereby opening switches B and D and closing switch C, which places the proper operating potential on the grid of tube 74. The arming tube 74 res at this point, discharging the condenser 66 whereupon the tube is extinguished and the condenser begins to recharge immediately causing tube 74 to re a second time at an interval determined by the time constant of condenser 66 and resistances 90, 92, 93 and 94 which maybe, for example, 15 seconds. The charge collecting condenser 67 has, in the meantime, been charging through closed switch C and upon the second firing of the arming tube 74 will add to the voltage at the cathode of tube 74 to elevate the potential on the control grid of the tube 75 to a value sufficient to fire tube 75. On ring of the tube 75, the condenser 96 discharges through the tube 75 and causes the detonator 100 to ignite, thereby exploding the mine.

It is necessary that the switch C be held closed for a predetermined optimum time of at least 15 seconds, for example, which is the assumed normal RC of the circuit for controlling re-ring or cycling of tube 74, in order to cause tube 75 to iire. Sea waves do not present a negative pressure cycle of sufficient duration to hold switch C closed for the required predetermined optimum time. Therefore, switch C is opened and switches B and D are closed by the succeeding positive pressure half cycle of a wave. When switch B is closed, the condenser 67 is short circuited through resistances 95 and 96 thereby restoring the device to the initial readied condition, i.e. placing the circuit` in readiness for response to a negative pressure signal of proper amplitude-time function. By reason of this arrangement, if the circuit is armed by the positive pressure of a wave, it cannot subsequently be red by a vessel moving athwartship with respect to the mine as the succeeding positive pressure half cycles ofthe wave cause switch B to close. When switch D is closed, condenser `66 is charged from battery 77 through resistance 97.

Tides are compensated -for by the orifice 15 which permits pressure equalization in the chambers 4 and 7.

lf aship having a positive pressure peak followed by a negative pressure region which is of great magnitude passes over the mine, it is not necessary that a time interval of 15 seconds pass between the rst and second rings of tube 74 since such a pressure signature is peculiar to large vessels only. Therefore, an accelerating means is provided which by means of bellows 52, 53

v and 54 cuts out the resistances E, F and G respectively in accordance With the progressively increased setting of the bellows. This reduces the resistance in the RC circuit of tube 7-4, allowing the condenser 66 to charge more rapidly, and ultimately tiring tube 74 more rapidly. Since condenser 67 charges quite rapidly on closing switch C, the tube 75 is tired sooner also, thereby exploding the miner Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the inventionV may be practiced otherwise than as speciiically described.

The invention described herein'may be manufactured and used by or'for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A pressure-time responsive device operable in response to a predetermined code of pressures comprising means responsive to a first predetermined pressure for initially preparing said device for operation, means. for causing the operation of said device in response to a second predetermined pressure existing for a predetermined minimum time interval, and means for reducing said predetermined minimum time interval when said second pressure is of relatively large magnitude.

2. A pressure-time responsive device operable in response to a predetermined `code of pressures comprising means responsive to a lirst predetermined pressure for initially preparing said device for operation, means for causing the operation of said device in response to a v second predetermined pressure existing for a predetermined minimum time interval, means for reducing said predetermined minimum time interval when said second pressure is of relatively large magnitude, and means for returning said device to the initial prepared condition in response to the 'cessation of the second pressure before 'the expiration of the predetermined minimum time Vinterval.

3. A marine mine Atiring device operable to arm and fire a mine in response to a vessels pressure signature having 4.' A marine mine iiring device operable to arm and i tire a mine in response to a vessels pressure signature having a positive pressure peak and a negative pressure region, comprising, means responsive to a predetermined pressure of the positive pressure peak for initially arming the mine, means for tiring the mine in response to the existence for a predetermined minimum time interval of a predetermined pressure of said negative pressure region, means for reducing the predetermined minimum time interval in response to a pressure of said negative pressure region of'relatively large magnitude, and means for returning said device to the initial armed condition in response to the cessation of the predetermined pressure of said negative pressure region before the expiration of the predetermined minimum time interval.

5. In a pressure responsive device selectively responsive to a predetermined code of pressures for operating aV switchAcontrolled electrical circuit comprising a housing having Va rst end portion and a second end portion, said rst end portion having a plurality of holes in the side walls thereof, a plate mounted in said housing having a pressure equalizing oriiice and a plurality of vents therethrough, said plate forming-a control chamber at said rst end portion and a base pressure chamber at said second end portion, a pressure responsive member exposed to a pressure signal conducting medium and mounted on said ihousing in pressure communication with said control chamber through said plurality of holes, a plurality of graduated pressure responsive switch operating members individual to said plurality of vents and mounted in said control chamber on said plate in communication with said base pressure chamber through said Vvents, and a depth compensating bellows mounted on said plate within said control chamber and having a plurality of switches mounted thereon in operative relation with respect to said plurality of switch operating members.

6. A pressure-time responsive device operable in response to a predetermined code of pressures comprising trst means responsive to a predetermined positive pressure for placing said device in a prepared condition for operation, Vsecond means responsive to a predetermined negative pressure existing for a predetermined time inlterval for causing said device to operate, means responsive to a change in pressure from nega-tive to positive prior to the passage of said time interval for returning said device to the prepared condition, and means responsive to negative pressure of relatively great magnitude .ffor causing said device to operate in less lthan said predetermined time duration.

' 7. In a mine firing' device, the combination of detonating means, and a pressure responsive device adapted to re -said detonating means in response to Ithe pressure signature of a vessel, said device comprising, lirst means responsive to positive pressure resident in said signature `to initially arm said mine, second means responsive to negative pressure resident `in said signature and existing for a predetermined time interval to re said detonator, third means responsive to a cessation of said negative pressure before the passage of said predetermined time interval to return said mine to said initially armed condition, and fourth means responsive to'negative pressures of relatively large magnitudes resident in vsaid signature for causing said detonator to tire before the passage of said predetermined time interval.

8. A pressure-time responsive electronic device responsive .to a predetermined Vcode of pressures comprising power supply means; an electric gas discharge device connected to said supply means and having an anode, a cathode and grid; an R.C. circuit having a first condenser connected to said cathode for maintaining the proper bias on said cathode; first bellows actuated switch means responsive -torpositive pressure for connecting said R.C. circuit to said power supply means to place a charge on said first condenser, a second condenser connected to said grid for .building up the voltage on said grid as the condenser is charged, second bellows actuated switch means responsive to negative pressure for connecting said condenser to said power supply means, means for shortcircuiting said second condenser when said second switch means is opened, third bel-lows actuated switch means responsive to negative pressure, means actuated by said )third means for supplying the proper operating bias to the grid :in additive relation to said voltage built up thereon and including an R.C. circuit which delays such supply for a predetermined time period, and `fourth bellows actuated switch means responsive -to negative pressures of relatively large magnitudes lfor reducing said predetermined time period-thereby causing said discharge device to fire more rapidly.

9. A pressure-time responsive electronic device responsive to a predetermined code ofA pressures comprising, power supply means, an electric gas discharge device connected to said power means having an anode, a control grid, and a cathode; first means connected to said cathode and said power means for conditioning said discharge device for operation and comprising a switch, positive pressure actuated means for closing said switch, and a first R.C. circuit for maintaining the proper bias on said cathode for a predetermined time after said switch is opened; second means connected to said control grid and said power means for rendering said device conductive and comprising a condenser, a second switch, negative pressure actuated means for closing -said second switch to charge said condenser, means for short circuit-ing said condenser when said second switch is open, means lfor adding voltage sufiicient to operate said electric discharge device to the voltage of said condenser comprising a discharge tube, a second R.C. circuit having a predetermined time constant controlling the firing of said tube, a third switch 4in the second R.C. circuit, negative pressure actuated means for maintaining said third swi-tch closed, said second R.C. circuit having a plurality of resistors, a plurality of switch means connected to said resistors for short-circuiting their respective resistors, and a plurality of means actuated by negative pressures of relatively large magnitudes for successively closing said -switch means as the large magnitude negative pressures increase.

10. A device of the character described responsive to a predetermined code of pressure signals comprising a condenser, means 4for charging said condenser to a predetermined potential in response to a predetermined pressure signal, means connected to said condenser responsive to a predetermined pressure signal existing for a predetermined time tfor providing an increased voltage at said condenser, and additional means operatively connected to said condenser for providing said increased voltage at the condenser in less than said predetermined time in response to a relatively large pressure signal.

1l. A pressure responsive device selectively responsive to 4a predetermined code of pressures comprising, a source of current, an electric gas discharge device connected to said source and having an anode, a cathode and grid, means responsive to positive pressure of short time duration to prepare said cathode for current conducting condition for a predetermined time period, means connected to said source responsive to negative pressure of a predetermined minimum magnitude and minimum time duration for building up the potential on said grid to a value sufficient to fire said electric device within said time period, and means responsive to negative pressures of relatively large magnitude for accelerating the grid potential build-up thereby to cause said device to fire in less time than said predetermined minimum time duration.

12. A pressure responsive device selectively responsive to a code of pressures comprising, power source means; an electric gas discharge tube connected to said power source means and having an anode, a cathode and a grid; means responsive to positive pressure to connect said cathode to said power source means to prepare said cathode for current conducting condition, said means including an R-C circuit having a predetermined time constant for maintaining said cathode in current conducting condition for a predetermined period of time; means connected to said power source means and responsive to negative pressure of a predetermined minimum magnitude and minimum time period for building up the potential on said grid to a value sufiicient to fire said electric tube; and means responsive to relatively large negative pressures for reducing the time period for building up the potential on said grid thereby to cause said tube to fire more rapidly.

13. In a control circuit of the character disclosed, the combination of first and second cold cathode tubes each having anode, cathode and control grid elements, first and second cathode load resistors individual to said tubes, first and second initially charged condensers connected respectively across the series combinations of the main discharge gaps of the tubes and the cathode load resistors individual thereto, the charge on each of said first and second condenser being sufficient to render the tube individual thereto conducting when an operating voltage corresponding to the control gap break down potential thereof is applied between the control grid and cathode elements of the tube, a third condenser coupling the cathode element of the first tube to the ygrid element of the second tube, a coupling resistor interconnecting said control grid elements, a battery including a low potential section connected between said cathode load resistors so as to negatively bias said second tube, a fourth condenser shunted across the cathode load resistor of the second tube, means for momentarily charging said fourth condenser in a direction to counterbalance said negative bias on the second tube, a first switch means for applying said operating voltage from said battery across the control gap ot the first tube through said third condenser when the switch means is operated from an initial position to a moved position thereby to render the first tube conducting to discharge said first condenser therethrough and simultaneously therewith to charge the third condenser from the battery whereby the voltage across the control gap of the second tube is elevated by the voltage developed on the third condenser, said first switch means being constructed and arranged to discharge said third condenser through said coupling resistor and the first load resistor when the first switch means is returned to said initial position, a second switch means for recharging the first condenser from said battery to a potential sufficient to render the first tube conducting a second time whereby the voltage developed across the first load resistor adds to the voltage developed on the third condenser sufiiciently to apply said operating potential to the control gap of the second tube to render the second tube conducting, and an electroresponsive device arranged to be operated by the energy discharged from the second condenser as the second tube is rendered conducting.

14. A pressure-time responsive electronic device responsive to a predetermined code of pressures comprising power supply means, a cold cathode discharge tube connected to said power means, first means connected to said tube for conditioning the tube for operation and comprising a switch, positive pressure actuated means for closing said switch, an R.C. circuit for maintaining the proper bias on said tube for a predetermined period of time after said switch is opened, second means connected to said tube and power means for rendering said tube conductive and comprising a condenser, a second switch,

negative pressure actuated means for closing said second switch to charge said condenser, means for short circuit# in the second R.C. circuit, and means responsive to negative pressure for maintaining said switch means closed.

References Cited in the iile of this patent i UNITED STATES PATENTS 2,388,459 Allen n Nov. 6. 1945

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