US2920562A

US2920562A - Mine firing mechanism

Info

Publication number: US2920562A
Application number: US559306A
Authority: US
Inventors: John F Toomey; Ellis M Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-10-18
Filing date: 1944-10-18
Publication date: 1960-01-12
Anticipated expiration: 1977-01-12

Description

1960 J. F. TOOMEY ET AL MINE FIRING MECHANISM 4 Sheets-She 1 Filed Oct. 18, 1944 F I Z I I gwue/wfotd J. F. TOO MEY' E. M. BROWN Jan. 12, 1960 J. F. TOOMEY ET AL 2,920,562

MINE FIRING MECHANISM Filed Oct. 18, 1944 4 Sheets-Sheet 2 J. F. TOOMEY E. M. BROWN Jan. 12, 1960 Filed Oct. 18, 1944 J. F. TOOMEY ET AL MINE FIRING MECHANISM 4 Sheets-Sheet 3 J. F. TOOMEY E. M. BROWN Jan. 12, 1960 J. F. TOOMEY ET AL 2,920,562

MINE FIRING MECHANISM Filed Oct. 18, 1944 I 4 Sheets-Sheet 4 grwc/rvfo m J. E TOOMEY E. M. BROWN MINE FIRING MECHANISM John F. Toomey, Floral Park, N.Y., and Ellis M. Brown, Dallas, Tex.

Application October 18, 1944, Serial No. 559,306

19 Claims. (Cl. 10218) (Granted under Title 35, US. Code (1952), sec. 266) This invention relates to firing mechanisms for a mine and more particularly to a firing mechanism in which a plurality of control circuits are closed in predetermined time relation by a motor driven timing device selectively under control of a signal received through the water by a signal detecting device.

It is the usual practice, in certain types of mines, to cause the mine to become active in response to a particular characteristic of a signal received from a vessel within the vicinity of the mine wherein means are employed for preventing the mine from being fired until a predetermined period of time has elapsed after the particular characteristic of the signal has been received. When this predetermined period of time has elapsed the mine is armed or merely placed in condition to receive a second signal or a second characteristic of the original signal accompanying the vessel, as the case may be, and remains armed for a period of time sufiicient to receive the second characteristic or signal. In the event that the second characteristic or signal is received within the armed period of the mine, the mine is exploded or a signal corresponding to a pair of such signals or signal characteristics is stored within a storage mechanism, as the case may be. When a sufiicient number of pairs of signal indications corresponding to the first and second of said signals respectively are received in predetermined time space relation and a signal corresponding thereto is stored by the aforesaid storage mechanism, the mine is exploded. In the event, however, that a second signal is not received during the armed period of the mine, the mine firing control mechanism is restored to normal without increasing the number of signal indications stored by the storage mechanisms and without firing the mine.

In devices heretofore proposed for controlling the firing of a mine selectively in accordance with the reception of a pair of signals corresponding to difierent characteristics or elemental portions of a signal received through the water or from two signals received through the water, as the case may be, within a predetermined period of time it has been the usual practice to employ certain storage mechanisms and time measuring delay devices comprising switch mechanisms both of the step-by-step type and of the type adapted to control the time of operation of the switching contacts thereof by clock movements, escapement devices, dash-pots and the like. Such devices have not proved altogether satisfactory in service for the reason that the devices are relatively susceptible to damage or injury thereto as the result of the shock or blow which the mine receives at the moment of launching, particularly in the case where the mines are launched from an aircraft in flight by reason of the relatively delicate elements comprising the structure.

It has been found in practice that these difliculties can be obviated by the use of a motor driven mechanism such, for example, as that disclosed and claimed in the copending application of Seth W. Booth et al. for Firing Control Mechanism for a Mine, Serial No. 490,044, filed June 8, 1943. The mechanism of the aforesaid applica- 2,920,562 Patented Jan. 12, 1950 2 tion comprises two motor driven timing devices adapted to be set into operation by a signal detecting device selectively in accordance with the polarity of signals received by the signal detecting device, the term polarity as applied to the magnetic signature of a vessel, being defined herein as a variation in the direction of the magnetic field at a fixed point of reference as different portions of the vessel move past the point of reference. The signal detecting device comprises a circuit including an induction pick-up coil hereinafter referred to as a search coil and a sensitive relay such, for example, as a relay known in the art by the trade name of Sensitrol, whereby movement of a vessel within the magnetic field adjacent the search coil generates electromotive forces therein' of either polarity according to an increase or decrease in the strength of the field respectively. When either one of the motors operates, a pair of electrical contacts on the associated timing device operate to close a circuit to, a relay and a condenser which last named elements coact to restore the sensitive relay to its responsive condition and a second pair of contacts on the timing device operate to open the search coil circuit. When a signal of op posite polarity is received during the cycle of operations of the first motor driven timing device, the second motor is set into operation whereby contact means provided on the second timing device cause the search coil circuit to be opened and the sensitive relay to be restored to its responsive condition in order to render the mechanism responsive to subsequent signals. Other contacts associated with the second timing device are employed to close a circuit to a counting device and when a predetermined number of pairs of signals have been counted, a circuit is closed to the detonator, thereby firing the mine in response to a signal of opposite polarity received during the cycle of operations of the first timing device.

The foregoing mechanism is not generally satisfactory under all conditions of service for the reason that no means. are provided for opening the search coil circuit when successive signals of like polarity are received by the signal detecting device. However, in such a mech-- anism it is highly desirable to open the search coil after each signal has been received, regardless of the polarity of the signal, for the reason that interruption of the search coilcircuit prevents the storing of inductive energy in the search coil as changes occur in the magnetic field adjacent thereto, thereby preventing spurious actuation of the sensitive relay, which actuation otherwise might occur upon dissipation of such energy after the sensitive relay is restored to its responsive condition whereby a shortening of the live period of the mechanism results. The live period, as employed herein, is defined as that period of time during which the signal detecting device, including the sensitive relay, is in condition to respond to a change in the magnetic field adjacent thereto during a. cycle of operations of one of the two motor driven timing mechanisms.

It has been found in practice that the use of the aforedescribed means for restoring or resetting the Sensitrol to an initial responsive condition is not always satisfactory due to the susceptibility of the relay to damage to its working parts by shocks received thereby, which damage may render the relay incapable of operation, and due to the inherent leakage and breakdown characteristics of the condenser, which leakage or breakdown may render the condenser incapable of storing a sutficient' amount of energyto operate the relay or to maintain the relay in operation for a desired interval of time.

The structure and'operation of the present invention is generally similar to the mechanism disclosed and claimed in the aforesaid application of Seth W. Booth et al. and it achieves several distinct advantages by replacing the heretofore mentioned relay and condenser by a third motor driven timing or control device. A pair of cams are operatively secured to the shaft of the third motor and a plurality of electrical contactsare associated with the cams in such a manner that when either of the first two motor driven timing mechanisms is set into operation, a circuit is closed to the third motor whereby it is set into operation. During the cycle of operations of the third motor driven control mechanism, means are provided through the cam controlled electrical contacts thereof whereby the sensitive relay is invariably restored to its responsive condition with the movable contact element thereof intermediate two contacts and disengaged therefrom and the search coil circuit is opened by the contacts'of the control mechanism for a predetermined period of time controlled by the control mechanism in accordance with the setting of a variable resistive elementyas will more clearly appear as the description proceeds.

' One of the objects of the present invention is to provide a new and improved timing mechanism for selectively controlling the firing of a marine mine.

Another of the objects is to provide a new and improved control mechanism for a mine adapted to fire the mine in response to a signal indication comprising two elemental signal portions received in predetermined time relation through the surrounding water.

Another object is to provide a new and improved mechanism for firing a mine selectively in accordance with a predetermined number of signal indications received by a signal detecting device in which each of the signal indications comprises a pair of elemental signals received in predetermined time spaced relation from a vessel.

Another object is to provide new and improved means for restoring the sensitive relay to its responsive condition and for opening the search coil circuit each time the mechanism responds to a signal or elemental portion thereof received from a vessel in predetermined time spaced relation.

Another object resides in the provision, in a motor driven mechanism, of means for opening the search coil circuit each time the signal detecting device has received a ships signal or elemental portion thereof.

Anotheriobject resides in the provision of a new and improved mine firing control mechanism'having means settable at will for controlling the number of signals necessary to fire the mine.

Another object resides in the provision of a minefiring arrangement comprising a pair of firing and control mechanisms adapted to be set in operation selectively and successively in accordance with the polarity of signals received from a search coil respectively corresponding to changes in the magnetic field caused by a vessel moving within the vicinity of the mine.

A further object is the provision of a timing mechanism for a mine adapted to close a plurality of groups of contact elements invariably in predetermined timed relationship which is rugged in construction, and which possesses the additional qualities of ease of adjustment and testing and reliability of operation in service.

Still other objects, advantages and improvements will be apparent from the following description taken in connection with the accompanying drawings of which:

Fig. 1 is a view in section and partially broken away of a mine suitablefor use with the mine firing system of the present invention;

' Fig. 2 illustrates in diagrammatic form a complete system according to a preferred embodiment of the invention and suitable for use with the mine of Fig. 1;

.Fig. 3 is a view, partially broken away, of a mine according to an alternative form of the invention in which two manually settable switches are employed to set the ship counter to a predetermined setting;

I Fig. 4 is, a view, partially broken away and partially in section, showing the arrangement of the manually settable switches and the firing control employed therewith according to an alternate form of the invention; and,

Fig. 5 illustrates in diagrammatic form a complete system suitable for use with the mine shown in Figs. 3 and 4.

Referring now to'the drawings for a more complete understanding of the invention and more particularly to Fig. 1 thereof there is shown thereon a mine indicated generally by the numeral 10 having a casing 11 adapted to be sealed by a cap or cover '12 secured thereto as by the studs 13 and nuts 14 threaded thereon, a gasket 16 being preferably arranged between the cover and the casing to insure a watertight joint therebetween. There is arranged within the casing 11 a wall or partition 17 having an annular support 18 secured thereto and adapted to receive one end of an induction pickup coil 19 comprising a relatively large number of turns of wire arranged about a rod of iron or composed of a material sold under the trade name of Permalloy or Mumetal. The other end of the coil is disposed within a recessed portion 21 of the casing -11, suitable pads or cushions 22 being arranged between the ends of the coil and the recessed portion 21 and support 18 respectively to prevent damage or injury to the coil as the mine is launched.

The partition 17 also forms a chamber 2'3 within which is arranged an explosive charge 24 of TNT or the like suflicient to destroy a vessel and to impart a negative degree of buoyancy to the mine whereby the mine is adapted to come to rest on the bed of a body of water after being launched therein.

There is also provided within the chamber 23 a well 26 within which is arranged a booster charge 27, as is well known in the art to which the invention pertains. There is alsoarranged within the well 26 a hydrostat mechanism comprising a plunger or rod 28 slideably arranged within the support 29 and normally urged outwardly from the support by a spring 31 in engagement with the collar. 32 secured to the plunger. A flexible diaphragm 33 is clamped to the collar as by the nut 34, the diaphragm being maintained in a watertight relation with respect to the well 26 as by the bolts '36 and clamping ring 37. A soluble washer 38 is secured to the plunger as by the nut 39 thereby preventing the inward movement of the plunger until the mine has been planted for a period 'of time sufiicient to dissolve or soften the soluble washer. When this occurs, the detonating device 41 is moved by the plunger into an operative position with respect tothe booster charge 27. The detonatingdevice 41 is connected electrically by means of a pair of conductors within the cable 42 to a junction'or connecting box 43, a tube or duct 44 being provided between the well 26 and the partition 17 to support and b protect that portion of the cable disposed within the explosivecharge within the chamber 23.

The mine is also provided with a recess or well 46 wherein is arranged a hydrostat 47 adapted to set an arming clock 48 into operation in response to the movement of the hydrostat under the influence of the pressure of the surrounding water. The arming clock may be of any type suitable for the purpose adapted toclose a circuit between the pair of: conductors within the cable 49 connected thereto such, for example, as the armingclock described and claimed in the copending application of James B. Glennon et al. for Firing Mechanism for a Submarine Mine,'Serial No. 395,230, filed May 26, 1941. The cable 49 is preferably arranged within a tube or duct'51 extending between the well '46 and the partition '17. i c

From the foregoing, it will be apparent that the partition 17 divides the casing of the mine into two portions or chambers of'whi'ch'the :chamber 23, is filled with an explosive charge 2.4. The remaining chamber, indicated generally by the numeral 52,'has.arranged therein certain timing and mine firing tanner mechanisms indicated generally by the numeral 53 and a counting mechanism '54, hereinafter referred to as CD, adapted to count signal indications received from the control mechanism 53 and to cause the mine to be fired after a predetermined number of such indications have been counted. The

mechanisms

53 and 54 are electrically connected to the connecting box 43 by a plurality of suitable conductors or cables. The

mechanisms

53 and 54 are secured to the casing of the mine in any suitable manner as by the support 56, the support preferably having a well 57 therein within which is arranged a battery 58, hereinafter referred to as BA, a clamping device 59 secured to the support '56 as by the bolts 61 preferably being provided to prevent injury to the battery as the mine is launched.

A sensitive polarized relay 62, hereinafter referred to as SR, is operatively connected to the coil 19, the relay having a reset magnet 63, hereinafter referred to as RM, adapted to restore the movable element of the relay to an initial neutral position intermediate a pair of contacts. The relay is mounted in any suitable manner as by the support 64. There is also provided an inertia switch 66 secured to the casing of the mine as by the bolts 67 adapted to connect together, electrically, a pair of conductors within the cable 68 as the switch operates in response to a shock or impulse received by the mine. The switch may be of any type suitable for the purpose such, for example, as the inertia switch disclosed and claimed in the copending application of Seth W. Booth for Inertia Switch and Means Controlled Thereby, Serial No. 484,854, filed April 28, 1943.

When the mine receives a sudden shock or impulse such, for example, as may result from the explosion of a torpedo or another mine within the vicinity of the mine or as the result of a counter-mining operation, the operation of the inertia switch 66 prevents the mine from being fired by the shock received, as will more clearly appear as the description proceeds.

The operation of the system will best be understood by consideration of Fig. 2 of the drawings on which is shown in diagrammatic form a complete system in accordance with a prefered embodiment of the invention fitted for use with the mine of Fig. 1.

Let it be assumed, by way of example, that the switching devices 69, 71 and 72 are connected in the position shown in the solid outlines and that the counting device CD has been set to count 35 ships before the mine is fired. Let it further be assumed that the mine has been planted within a body of water of sufficient depth to cause the clock hydrostat 47 to operate, thereby setting the arming clock 48 into operation, and that a period of time has elapsed sufficient for the soluble washer 38 to dissolve and allow the detonating device 41 to be moved into operative relation with respect to the explosive boostercharge 27 by the pressure of the surrounding water against the flexible diaphragm 33 of the extender hydrostat.

With the connecting devices 69, 71 and 72 set in contact with

terminals

73, 74 and 76 respectively, as in the assumed example, the system is adapted to be controlled by pairs of signals received by the sensitive relay SR in which the first signal of the pair is of the opposite polarity from the remaining signal. When a signal comprising two elemental signal portions of opposite polarity respectively is received such that the second elemental portion of the signal is received within a predetermined period of time after the first elemental portion of the signal is received, the counting mechanism CD is set into operation to count signal indications corresponding respectively to each pair of signals or elemental signal portions of opposite polarity received by the sensitive relay SR. In the event that the second signal of the pair is of the opposite polarity to the first signal of the pair but is not received within a predetermined period of time, or the second signal is of the same polarity as the first 8 signal, the system comprising thecontrol devices T1, T2, and T3 restores to normal and the pair of signals is not counted by the counting mechanism CD.

Let it now be assumed, by way of example, that a vessel having a magnetic signature comprising an elemental portion or characteristic of one polarity followed by an elemental portion or characteristic of the opposite polarity moves within the vicinity of the mine or passes above the mine.

As the first portion of the magnetic signature moves into proximate relation with respect to the pickup coil 19, an electromotive force is generated within the pickup coil sufiicient to'operate the relay SR and cause the armature or movable contact element thereof to be moved into engagement with

contact

77 or 78, as the case may be. For the purpose of description itmay be assumed that the armature of SR moves into engagement with contact '78 and is held thereto by means of a small magnetic mass secured to the tip of the armature and adapted to be attracted by the permanent magnet 80 for a predetermined period of time. When this occurs, a circuit is closed from the negative terminal of battery BA by way of conductor 79, armature 81 and break contact of relay CR, conductor 82, armature and contact .78 of relay SR, conductor 83, contact springs 86 and 84 of cam 1B, conductor 87, motor M1, from whence the circuit is continued to ground thereby causing motor M1 to operate and set the timing device T1 into operation.

When the timing device T1 has operated for substantially one second, cam 1A causes contact springs 88 and 89 to be moved into engagement with each other thereby connecting motor M1 to the negative terminal of battery BA over the followingcircuit: negative terminal of battery BA, conductor 79, contact springs 88 and 89, conductor 87, motor M1 and thence to ground. The contact spring 88 is maintained in continuous engagement with contact spring 89 until the motor has been operating for a period of substantially one hundred and twenty seconds at which time the contact spring 88 is disengaged from contact spring 89 by the cam 1A and the motor is brought to rest at the completion of a cycle of operations of the timing device T1. When the motor M1 has operated for substantially three seconds during the aforesaid cycle of operations the cam assembly 91 thereof is actuated by the cam IE to the operated position and remains operated, for a period of substantially one hundred and seventeen seconds. As contact spring 86 moves into engagement with contact spring 92, a circuit is closed from negative battery on conductor 79 by way of armature 81 and break contact of relay CR, conductor 82, armature and contact 78 of relay SR, conductor 83, contact springs '86 and 92, conductor 93, switching device 71 and terminal 74, conductor 94, motor M3 from whence the circuit is continued to ground thereby causing motor M3 to operate and initiate a cycle of operations of the control device T3.

As motor M3 is set into operation, the movement of cam 3A causes contact springs 96 and 97 to move into engagement with each other thereby connecting motor M3 to the negative terminal of battery BA over the following circuit: negative terminal of battery BA, conductor 79, contact springs 96 and 97, conductor 94, motor M3 and thence to ground. The contact spring 96 is maintained in continuous engagement with contact spring 97 until M3 has been operating for a period of substantially one second at which time the contact spring 96 is disengaged from contact spring 97 by cam 3A and the motor M3 is brought to rest at the completion of a cycle of operations of the timing device T3. A variable resistance R is included in the operating circuit of motor M3 while

contacts

96 and 97 are closed whereby the time of a cycle of operations of the timing device T3 may be controlled by the setting of the variable resistor R.

When the contact springs 96 and 97 are moved into engagement with each other by cam 3A the contact springs 99 and 101 are concurrently moved into engages "7 n ent'fwitli each other whereby negative battery is applied to the reset magnet RM of the sensitive relay SR over the following circuit: negative terminal of battery BA, conductor 79, contact springs 99 and 101, conductor 102, reset magnet RM and thence to ground thereby operating the reset magnet- RM and restoring the armature of relay SR to a position

intermediate contacts

77 and 78 and disengaged therefrom. "Contact springs 101 and 99 are maintained in continuous engagement with each other until the timing device T3 has ended a cycle of operation, at which time contact spring 101 is disengaged from contact spring 99 by the cam 3A. A fraction of a second following the movement of contact springs 101 and 99- into engagement with each other by cam 3A, cam 3B causes contact springs 103 and 104 to be disengaged thereby interrupting the connection between the 7,

operating magnet OM of the relay SR and the induction pickup coil .19. However, this connection is restored when cam 33 has completed one revolution and relay SR is again in condition to operate in response to the electromotive force generated by the pickup coil 19 as the second elemental portion of the ships magnetic signature moves into eifective relation with the induction pickup coil 19. 7

Extremely small voltages are'generated by the pickup coil and, for this reason, two pairs of switch contacts 103104 are arrangcd'in parallel to insure that at least one pair of the switch contacts closes effectively to complete the' pickup coil circuit when the switch contacts are engaged. In'the event that the polarity of the second elemental portion of the ships signature is such as to cause the armature of the relay SR to move again into' engagement with contact 78 of relay SR duringthe cycle of operations of the timingdevice T1 by the electromotive force generated within the pickup coil 19, negative battery is applied to motor M3 byway of conductor 79', armature 81' and break contact of relay CR, conductor 82, armature and contact 78 of relay SR, conductor 83, contact springs 86 and 92, conductor 93, switching device 71 and contact terminal 74, conductor 94, motor M3 and thence'to ground, thereby setting motor M3 into operationand causing the armature of relay SR to be restored toa position

intermediate contacts

77 and 78 and disengaged therefrom. The operation of the timing device T3 also causes the connection between the operating magnet OM of the relay SR and the induction pickup coil 19 to be interrupted until the cycle of operations of the device T3 is complete.

Fromthe foregoing, it will be apparent that during the remaining portion of the cycle of operation of motor M1, the movement of the armature of relay SR into engagement with contact 78 causes operation of control device T3 which immediately restores the armature of relay SR to an initial unoperated position and interrupts the search coil circuit.

As the armature of relay SR moves into engagement with contact 77 thereof in response to thesecond elemental portion or signal of the pair of signals of opposite "polarity during a cycle of operations of timing device T1, a circuit is closed from the negative terminal of battery BA by way of conductor 79, armature 81 and break contact of relay CR, conductor 82, armature and contact 77 of relay SR, conductor 106, switching device 69 and contact terminal 73, conductor 107, contact springs 116 and 114, conductor 108, motor M2 from whence the circuit is continued to ground thereby causing motor M2 to operate and set the timing device T2 into operation during the cycle of operation of timing device T1. When motor M2 has been in operation for substantially one second, contact spring 109 is moved by cani 2A into engagement with contact spring 111 thereby applying negative battery to motor M2 over conductor 79, contact springs 109 and" 111, and conductor 8 I08 and maintaining motor M2 in continuous operation for one

revolution f'cams

2A and 2B.

As contact spring 112 is moved'by' cam 2A intofen gagementwith contact spring 113a circuit is closed from the negative terminal of battery B'A by way' of conductor "79; contact springs 118 and 119, conductor 121, contact springs 1112 and 1&3, conductor 1'22, contact springs 124 and 123, conductor 127, motor M4, from whence the circuit is continued to ground thereby causing motor M4 to operate andset into'operation the counting device CD to count a'signal indication corresponding to a vessel having a magnetic signature comprising two portions'of op.- posite polarity received in' predetermined time spaced relation by the induction pickup coil 19 and relay SR. When motor M4 has operated for substantially three seconds, contact spring 132 is moved by cam 4A into engagement with contact spring 131 thereby applying negative battery to motor M4 over conductor 79, contact springs 132 and 131, and conductor 127 establishing an operating circuit to maintain motor M4 in operation for one complete revolution of cam 4A. 'Cam 4A completes one revolution in one hundred and eighty seconds thereby bringing the counting device CD, including motor M4, to rest at the completion of a cycle of operations thereof.

When the contact spring 129 is moved by cam 4A into engagement with contact spring 128, the operating coil OM of the relay SR is short circuited through conductors 1'33 and 134 thereby rendering the induction pickup coil 19 ineffective to operate relay SR as a ships signature is received through the surrounding water during the cycle of operations of the counting device CD. Contact springs 137 and 138 are disengaged by the movement of cam 4A thereby preventing premature firing of the mine if, for any reason, contact springs 123 and 124 should not be disengaged at this time At the comple-. tion of a cycle of operations of counting device CD, the contact springs 1'37 and 138 are moved into engage? ment with each other whereby negative battery may be applied to the detonator 41 when the required number of ships have been counted by the counting device CD.

In the assumed example it will'be recalled that the counting device had been set to count the passage of thirty-five vessels before the contact spring 126 is moved into engagement with contact spring 124 by the cam 4B. Cam 4B, therefore, is moved through an angle corresponding to one thiry-fifth of the angular displacement of the cam from the adjusted position to the final armed position thereof during each revolution of the cam 4A corresponding to a cycle of operations of the counting device CD.

The counting device CD comprises a motor M4 adapted to operate a pair of

cams

4A and 4B. A gear box 147 is employed between the motor M4 and, cam 4A for the purpose of reducing the relative angular velocity between motor M4 and cam 4A such that cam 4A makes a revolution in seconds and a Geneva gear 148 is included between

cams

4A and 4B thereby causing cam 4B to be moved through a predetermined angle several seconds before cam 4A has completed one revolution. A plurality of cam controlled electrical contacts are associated with each of the

cams

4A and 4B respectively in such a manner as to short-circuit the operating magnet OM of relay SR and to count a vessel or fire the mine, as the case may be.

When the timing device T1 has operated for substantially one hundred and twentyseconds contact spring 88 thereof is disengaged from contact spring 89 by the cam 1A thereby interrupting the circuit to motor M1 and bringing the motor to rest. In a similar manner when timing device T2 has'been operating for substan: tially one hundred and twenty seconds contact spring 109 is disengaged from contact spring 111 by cam 2A thereby interrupting the circuitto motor M2 and bringing motor'MZ to. rest upon completionof a revolution of cam '2A. However, it will be understood that the counting device CD continues to operate after the timing devices T1 and T2 have been brought to rest by reason of the fact that the contact spring 132 is not disengaged from contact spring 131 until cam 4A has completed a revolution upon completion of a period of time of one hundred and eightly seconds. When this occurs, the maintaining circuit of motor M4 is interrupted and motor M4 is brought to rest.

Let it now be assumed, for the purpose of description, that the next succeeding thirty-two vessels have magnetic signatures of the same relative polarity as the first vessel which passed the mine. The foregoing cycles of operation of the timing devices T1 and T2 and the counting device CD are repeated, each of the timing and counting devices making one revolution in response to the passage of each of the vessels respectively as they pass the mine and relay SR and timing device T3 controlling the system during each of these cycles of operation in response to signals received from the induction pickup coil 19.

As the system is again set into operation in response to the approach of the thirty-fourth ship within the vicinity of the mine, the timing devices T1 and T2 are set into operation in succession thereby causing the operation of motor M4. When the motor M4 has been operating for substantially one hundred and sixty seconds, the contact spring 126 thereof is moved by cam 4B into engagement with contact spring 124 and is maintained in engagement therewith until the completion of a revolution of cam 4A. A circuit is thus closed from the contact spring 113 of cam 2A by way of conductor 122, contact springs 124 and 126, conductor 139, to contact spring 137 where the circuit is open due to the disengagement of contact springs 137 and 138. Upon completion of a cycle of operations of the counting deviceCD, contact springs 137 and 138 are moved into engagement with each other, however, the mine is not fired at this time for the reason that contact springs 1 12 and 113 are disengaged from each other due to the completion of a cycle of operations of timing device T2 before the contact springs 137 and 138 move into engagement with each other. The mine is now in an armed condition in readiness to be fired by signals received from the thirty-fifth ship.

As the thirty-fifth ship moves into the vicinity of the mine the first elemental portion of the ships signature causes the armature of relay SR to move into engagement with contact 78 thereof and thereby operate motor M1 and set timing device T1 into operation. When motor M1 has operated for substantially three seconds, the movement of contact spring 86 thereof into engagement with contact spring 92 causes motor M3 to start thereby initiating a cycle of operations of the timing device T3 which restores the armature of relay SR toits responsive position

intermediate contacts

77 and 78 and disengaged therefrom. During the cycle of operaitons of timing device T3, contact springs 103 and 104 are disengaged thereby opening the circuit between the induction pickup coil 19 and the operating magnet OM of the relay SR, this connection being restored when the timing device T-3 completes its cycle of operations. As the armature of the relay SR moves into engagement with contact 77 thereof in response to the second elemental portion of the ships signature, motor M2 is started thereby setting timing device T2 into operation during the operation of motor M1. When motor M2 has been operating for substantially one second, contact spring 116 is moved by cam 2A into engagement with contact spring '114 whereby a circuit is closed from the negative terminal of battery BA by way of conductor 79, contact springs 1-18 and 119, conductor 121, contact springs 112 and 113, conductor 122, contact springs 124 and 126, conductor 139, contact springs 137 and 138, conductor 136, detonator 41, from whence the circuit is continued to ground thereby operating the detonator 41' '10 and exploding the mine beneath the vulnerable portion of the thirty-fifth vessel.

In the event that any of the foregoing vessels have associated therewith a magnetic signature comprising two portions of opposite polarity such that the first portion of the magnetic signature causes the armature of relay SR to move to contact 77 and the second portion of the signature causes the armature of relay SR to move to the contact 78, the timing device T2 will be set into operation in response to the first signal and timing device T1 will be set into operation in response to the second signal. The operation of timing devices T1 and T2 in the order named is believed to be clearly apparent from the foregoing detailed description and the circuits controlling the operation of these. devices under this condition of operation are, therefore, not henceforth described in complete detail. It will be noted, however, that the timing device T3 operates to reset the relay SR and interrupt the search coil circuit during the cycle of operations of timing devices T1 and T2 and in the event that the second portion of a signal received by the signal detecting device is of the same polarity as the first portion of the signal, motor M3 is started causing timing device T3 to operate, thereby resetting the relay SR and interrupting the search coil circuit.

As the armature of relay SR moves. into engagement with contact 78 in response to a signal of opposite po-, larity corresponding -to the second portion of the ships signature received while the timing device T2 is performing a cycle of operations, motor M1 is started thereby setting timing device T1 into operation. Contact springs 118 and 119 of timing device T1 are actuated to a circuit closing position one second after motor M1 has been set into operation thereby causing motor M4 of counting device CD to start and set the counting device CD into operation over the following circuit: negative 161'? minal of battery BA, conductor 79, contact springs 118 and 119, conductor 121, contact springs 1-12 and 113, conductor 122, contact springs 124 and 123, conductor 127,-motor M4 from whence the circuit is continued to ground thereby starting motor M4 and setting counting device CD into operation to count a vessel or to close in part the firing circuit to the detonator 41, as the case may be. When contact springs 128 and 129 of the counting device CD are moved into engagement with each other,

conductors

133 and 134 are connected together thus short-circuiting the operating magnet OM of relay SR until cam 4A has completed one revolution corresponding to a cycle of operations of the counting device CD.

Three seconds after motor M1 has started contact springs 86 and 92 are moved into engagement with each other thereby closing a circuit to motor M3 by way of negative terminal of battery BA, conductor 79, armature 81 and break contact of relay CR, conductor 82, armature and contact 78 of relay SR, conductor 83, contact springs 86 and 92, conductor 93, switching device 71 and contact terminal 74, conductor 94, motor M3 and thence to ground whereby motor M3 is caused to start and initiate a cycle of operations of timing device T3. When contact springs 103 and 104 are disengaged by action of cam 3B the circuit between the induction pickup coil19 and operating magnet OM of relay SR is interrupted for a predetermined period of time.

In the event that it is desired to control the firing of a mine by pairs of signals of either polarity in which the first signal of the pair is of the same polarity as the remaining signal of the pair or of a different polarity than the remaining signal of the pair, the switching devices 69, 71 and 72 are connected in the positions shown in the dashed outlines on Fig. 2 of the drawings in engagement with

terminals

75, 73, and 74 respectively. With the switching device 69 in engagement with terminal 75, conductor 83 is connected to conductor 106 thereby establishing an electrical connection between. con-1 tact 77 and 78' of relay SR such that negative battery is applied to conductor 83 by operation 'of relay SR regardless .of the polarity of the signal receivedby the signal detecting device of suflicient strength tomove the armature of relay SR to a circuit closing position.

a With the contact springs of timing device T1 moved to the position corresponding to the rest position of cams 1A and 1B associated therewith, the operation of relay SR applies battery by way of conductor '83, contact springs 86 and 84,'conductor 87, motor M1 from whence the circuit is continued to ground thereby causing motor M1 to' start and the timing device T1 immediately to be set into operation before motor M2 is started. As contact spring 86 of timing device T1 is moved into engagement with contact spring 92 thereof subsequent operation of relay SR in response to a second signal of. either polarity comprising a second elemental portion of a ships signature applies battery by way of conductor 83, contact springs 86 and 92, conductor 93, switching device 71, terminal 73, conductor 127, contact springs 116 and 114, conductor 108, motor M2 from whence the circuit is continued to ground thereby starting motor M2 and setting timing device T2 into operation while timing device T1 is performing a cycle of operations.

When the cycle of operations of timing device T2 has progressed sufliciently, contact springs 112 and'113. thereof are moved into engagement with each other thereby applying battery to motor M4 by way of conductor 79, contact springs 118 and 119, conductor 121, contact springs 112 and 113, conductor 122, contact springs 124 and 123, conductor 127, motor M4 ifrom whence the circuit is continued to ground thereby causing motor M4 to start and set the counting device CD into operation It will be noted thatwhen the timing devices T1 and T2 are set into operation selectively or successively, a circuit is closed to motor M3 causing it' to start and initiate a cycle of operations of the timing device T3 whereby the sensitive relay SR is reset and the circuit between the induction pickup coil 19 and operating'magnet OM of relay SR is interrupted for a predetermined period of time depending upon the setting of resistance R.

From the foregoing description it will be clearly apparent that with the switching devices 69, 71 and 72 in engagement with the terminals-75, Band 74 respectively, the timing device T1 is invariably set into operation in response toa signal of either polarity received by the induction pickup coil 19 and when a predetermined period of time has elapsed the timing device T2 is set into operation by relay SR in response to a signal of either polarity received by the induction pickup coil 19. InVthe event that the second signal received is of insufficient strength to operate relay SR during the interval of time between the restoration to normal of relay SR by the timing device T3 and the remaining portion of the cycle of'operations of timing device T1, timing device T2 is not started and timing device T1 comes to rest at the completion of its cycle of operations without causing the counting device CD to be set intouoperation.

The operation of the system of Fig. 2 in response to a countermine shock will now be described; As the contacts of the inertia switch IS close, negative battery is applied to the counter-mine relay CR by way of conductor 79, armature 81 and break contact ofrelay CR, conductor 82, contacts of inertia switch IS, conductor 144, relay CR from whence the circuit is continued to ground thereby energizing relay CR and causing its armature 81 to be moved to the make contact thereof. As armature 81 of relay CR engages the make contact thereof, negative battery is applied to motor M3 over the following circuit: negative terminal of battery BA, conductor 79, armature 81 and make contact of relay CR, conductor 94, motor M3 from'whence the circuit is continued to' ground thereby causing motor M3 to operate and perform a cycle of operations'of' timing device T3 which resets the relay SR and opens the. search coil circuit,

thereby preventing the engagement of the armature of rel'aySR with either

contacts

77 or 78 thereof. A condenser "14.6 is'preferably connected across the contacts of the inertia switch IS to prevent the release of relay CR while the contacts are vibrating in response to a series of rapid impulses or sudden variations in'pressure caused by the countermining operation. When the countermine shock has abated sufliciently for relay CR to release, battery is removed from motor M3 causing the motor to be brought to rest and the reset magnet RM of relay SR to release and, as the armature 81 of relay CR moves into engagement with break contact thereof, battery is again applied to the armature of relay SR and the system is in readiness to receive a signal from theinduction pickup coil 19.

In the event that the countermine shock is received while only one of the motors M1 or M2 is running and before sufl'lcient time has elapsed for the second motor to be started in response to the operation of relay SR, the operation of motor M3 prevents the premature starting of the second motor as the result of the countermine shock. In the event that the countermine shock is received while the timing device T2 is operating, the motors of the first and second timing devices complete their cycle of operations and the counting device CD is set in operation to count a ship regardless of the countermine impulse received by the mine.

Referring now to Figs. 3, 4 and 5 whereon is shown an alternate form of the invention adapted to fire a mine in response to a pair of signals of either polarity received in predetermined time spaced relation bythe induction pickup coil 19, and more specifically to Figs. 3 and 4, there is shown thereon a mine 149 having the same general structure as the mine of Fig. 1. The mine 149 comprises a casing '150 having arranged therein a firing mechanism 151 adapted to be set into operation in response to signals received by the induction pickup coil 19. The'mine 149 is also provided with a recessed portion or well 152 wherein is arranged a pair of manually

settable switches

153 and 154 with position indicating elements and indicia associated therewith adapted to control the number of ships which pass within the vicinity of the mine before the firing mechanism 151 fires the mine. Electrical connections between the

switches

153 and 154 and the firing mechanism 151 are maintained by a cable 156 preferably disposed in a tube or duct 158, and the connecting box 43. The

switches

153 and 154 are tens and units switches, respectively, and by removing the bolts 157 these switches may be manually set to any desired setting with a tool suitable for the purpose such, for example, as a screw driver.

' For a more complete understanding of the operation of the mine of Fig. 4, reference is made to Fig. 5 of the drawings whereon is shown in diagrammatic form a complete system according to antalternative form of the;

cycle of operations of the counting device CD-l. The

counting device is also provided with a system of

gears

162 and 163 including Geneva movements arranged in such a manner that one revolution of cam 4A actuates the wiper 164 of the units switch 174 to a new setting just before the revolution is completed and while one revolution of wiper 164 is being completed, the wiper 166 of the tens switch 176' is advanced into engagement with the next succeeding switch contact.

The operation of timing devices T1 and T2 is believed to be clearly apparent from the foregoing detailed description and the circuits controlling the operation of. these;

'13 devices are, therefore, not henceforth described in complete ,detail.

For the purpose of description, let it be assumed that the counting device CD-l has been set to fire the mine in response to a pair of signals of opposite polarity received by the induction pickup coil 19 from the second vessel moving within the vicinity of the mine. For this arrangement the pointer of the tens switch 153 is set to engage the contact thereof and the pointer of the units switch 154 is set into engagement with the contact 2, whereas the

wipers

164 and 166 of the counting device CD-l are in their home positions in engagement with their

contacts

1 and 0 respectively. When the first ship moves within the vicinity of the mine or passes above the mine, timing devices T1 and T2 are set into operation and if it be assumed that the timing device T2 is set into operation during the cycle of operation of timing device T1,.negative battery is applied to motor M4 over the following circuit: negative terminal of battery BA, conductor 79, contact springs 118 and 119, conductor 121, Contact springs 112 and 113, conductor 122, motor M4 from whence the circuit is continued to ground thereby causing motor M4 to start, initiating a cycle of operations of the counting device CD-l corresponding to a period of time of one hundred and eighty seconds. When motor M4 has been operating for substantially three seconds, contact spring 132 is moved into engagement with contact spring 131 thereby applying negative battery to motor M4 over conductor 79, contact springs 132 and 131, conductor 122, motor M4 and thence to ground whereby a circuit is established which maintains motor M4 in operation for one hundred and eighty seconds corresponding to the time of one revolution of cam 4A.

Concurrently with the movement of contact springs 132 and 131 into engagement with each other, cam 4A also moves contact springs 128 and 129 into engagement with each other whereby the operating magnet OM is short circuited during the remaining portion of the cycle of operations of the counting device CD-l, When timing devices T1 and T2 have ceased operating and substantially twenty-five seconds before cam 4A completes one revolution, the units wiper 164 is moved from its initial home position 1 into engagement with contact 2 thereof by the system of gears 162 and the Geneva movement thereby arming the mine. However, the mine is not fired at this time for the reason that contact springs 168 and 169 are disengaged from each other thereby maintaining an open circuit from the negative terminal of battery BA to the detonator 41.

p A second vessel moving Within the vicinity of the mine will cause timing devices T1 and T2 to be set into operation. One second after motor M2 of timing device T2 has started, cam'2Athereof causes motor M4 to be again started thereby initiating a cycle of operations of counting device CD4, and two seconds later cam 28 causes contact springs 168 and 169 to be moved into engagement with each other whereby negative battery is applied to the detonator 41 over the following circuitz negative terminal of battery BA, conductor 79, then to contact

springs

118 and 119, conductor 121, contact springs 112 and 113, and contact springs 132 and 131 in parallel, conductor 122, contact springs 169 and 168, conductor 171, contact arm of switch 153, wiper 166 and contact thereof, wiper 164 and contact 167 thereof, conductor 172, contact arm of switch 154, conductor 173, detonator 41 from whence the circuit is continued to ground thereby firing the mine. If it is desired to count ten or more ships before firing the mine, the tens wiper 166 is moved to a new setting by the system of gears 163. each time the units wiper 164 has completed one revolution.

It will be noted, however, that whenever the timing devices T1 or T2 perform a cycle of operations the timing device T3 is set into operationthereby resetting the sensi-,

tive relay SR and interrupting the search coil circuit for a predetermined period of time.

Briefly stated in summary, the invention provides a new and improved mine firing mechanism comprising a pair of motor driven timing and control devices which coact in response to a pair of signals of like polarity or selectively in response to a pair of signals of unlike polarity received from a vessel by a signal detecting device to effect a counting operation or fire a mine, as the case may be. The mechanism also comprises an additional motor driven timing and control device which operates to reset a sensitive relay associated with the detecting device and interrupt the signal detecting circuit thereto for a predetermined period of time when the mechanism responds to each one of a plurality of successive signals ofeither polarity received from a vessel. From the foregoing, it will be apparent that the foregoing arrangement of a plurality of like devices achieves simplicity of assembly and wiring and provides a mechanism which is rugged in construction and durable in service. In the alternate form of the invention, a new and improved ship counting device comprising two manually settable switches contained in the mine case proper is provided, thereby facilitating the ease with which the counting mechanism may be preset to select'for destruction a particular vessel moving within the vicinity of the mine.

While the invention has been described with reference to two examples thereof which give satisfactory results, it will be understood that this has been done for purposes of disclosure and that various changes and substitutions may be readily apparent to those skilled in the art, after understanding the invention disclosed herein, and that the terms employed in the claims are, therefore, to be considered as words of description rather than of limitation.

The invention herein described and claimed may be manufactured and used by or for the Government. of the United States of America for governmental purposes without 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:

1. In a system for firing a mine in response to signals received through the surrounding water, a device for detecting said signals, a relay controlled by said signal detecting device, a firing control circuit, a pair of motor driven timing devices operable in unit cycles, means on each of the devices of said pair for closing said circuit during a cycle of operations thereof, means controlled by said relay for setting said timing devices into operation selectively in accordance with the polarity of signals detected by said signal detecting device thereby to initiate a cycle of operations of said timing devices, a third motor driven timing device, means controlled by at least one of said pair of timing devices for initiating a cycle of operations of said third timing device during a cycle of operatons of said one of said pair of timing devices, and means on said third timing device for rendering the signal detecting device ineffective for a predetermined period of time during the cycle of operations of the third timing device.

2. In a system of the character disclosed for firing a mine arranged in a magnetic field, means for detecting variations in said magnetic field, a relay connected to said detecting means and adapted to be operated thereby, said relay having a contact element movable in either direction from an initial unoperated position to either of two circuit closing positions selectively in accordance with an increase or decrease in the strength of said magnetic field detected by said detecting means, a pair of motor driven timing devices adapted to be set into operation selectively in accordance with the direction of movement of said element as the element moves to a circuit closing position, a firing control circuit, means on each of the devices of said pair for closing said circuit during a cycle of operations thereof, a third motor driven timing device, means controlled by said third motor driven timing device for restoring said contact element to said initial unoperated position, and means controlled "by at least one of said pair of timing devices for initiating a cycle of operations of said third timing device during a cycle of operations of said one of said pair of timing devices. i

3. In a signal detecting system, a signal detecting device, a relay having a contact element movable from an initial unoperated position to a circuit closin'g'position, an electrical circuit maintaining electrical'connection between said signal detectingdevice and said relay, a motor driven timing device, means controlled by said contact element for initiating a cycle of operations of said timing device when the contact element is moved to said circuit closing position in response to asignal received by said signal detecting device, a second motor driven timing device adapted to interrupt saidelectrical circuit during a cycle of operations thereof whereby said relay is rendered unresponsive for a predetermined period of time to signals received by said signal detecting device, means controlled by said second timing device for restoring said contact element'to said initial unoperated position while the second timing device is performing a cycle of operations, and means controlled by said first timing device for initiating a cycle of operations of said second timing device during a cycle'of operations of the first timing device. a

4. In a system of the character disclosed for firing'a mine arranged in a magnetic field, an induction pickup coil adapted to detect variations in said magnetic field, a sensitive relay having a contact element movable in either direction from an initial unoperated position to either oftwo circuit closing positions selectively in accordance with an increase or decrease in the strength of said magnetic field detected by said pickup coil, an. electrical circuit maintaining electrical connection between said pickup coil and said relay, a pair of motor driven timing devices, means controlled by said relay for setting said pair of timing devices-into operation in succession and selectively in accordance with the direction of movement of said contact element tov a circuit closing position thereby initiating a cycle of operations of each of said timing devices, a firing circuit, means on each of said timing devices for closing the firing control circuit during said cycle of operations, a third motor driven timing device having means adapted to interrupt said electrical circuit for a predetermined period. of time, means on said relay and controlled by said third timing device for restoring said contact element to said initial unoperated position during said predetermined period of time, and means .controlled by at least one of said pair of timing devices .for initiating a cycle of operations of said third timing device during a cycle of operations of said one ofsaid pair of timing devices. e v v 5. In a system for firing a mine in response. to a pair of signals received in predetermined time spaced relation through the surrounding water, a signal detecting device, a relay adapted to be operated by said signal detecting device as a signal is detected thereby, said relay having a contact element movable from .an ini-. tial unoperated position to, a circuit closing position as the relay operates, a first motor driven timing device, means controlled by said relay for initiating a cycle. of operations of said first timingdevice when the relay operates in response to a first of said pair of signals detected by said signal detecting device, a second motor driven timing device adapted to render said signal detecting device ineffective for a predetermined period of time to operate said relay means controlled by said first timing device for initiating a cycle ofoperations of said second timing device during a cycle of operations of the first timing device, meanscontrolled by said second timing device for restoring said relay to said initial 'uno'perate'd posiiio'n dining a cycle orphana es of said second timing device, a third motor drivennming device, means controlled by said relay for initiating a cycle of operations ofj'said thirdtimingdevice when the relay is again operated in, response to asecond signal of said pair of signals detected by said fsign al detecting device, detonating means, a firing circuit including said detonating means, and means for closing said firing circuit when said first and-third timing devicesare performing a cycle of operations concurrently. 7 c v -6. In a system for firing a minearranged in amagnetic field, an induction pickup coiladapted to detect variations in said magnetic field, anelectrical relay having a pair of normallyijopen contacts thereon, means on said relay and controlled 'by said pickup coil :for engaging 'said'conta'cts selectively as the relay operates selectively in accordancewith an increase or decrease in the strength of said magnetic field detected by said pickup coil, an electrical circuit: adapted to maintain electrical connection between said pickup coil and said relay, a pair of motor driven timing, devices adapted to perform cyclic operations and to be set into operation selectively in accordance 'Withthe contact of said pair of contacts engaged by said engaging means, a third motor driven timingv device adapted to be set. into operation during a cycle of operations ofcat least one of said pair of timing devices, means on said pairot timing devices for initiating a cycle of operations of said tected by said pickup coil, detonating means, a firing circuit including said detonating means, and meansfor closing said firing circuit when said pair. of timing devices are performing a cycle of operations concurrently.

7. In a system for firing a mine in response to a predetermined number of pairs of signals received through the surrounding water in predetermined time spaced relation, signal receiving means, a relay adapted to be operated by said signal receiving rnean s,.a motor driven timing device adapted to be setinto operation to perform a cycle of operations as said relayresponds to a first of said pair of signals, a second motor driven timing device adapted to beset into operation by said first timing device and'having control means inicluding a plurality. of contact elements. for,mornenta'rily resetting said relayto an initial responsive conditionand for renderingthe relay unresponsive to subsequent signals a for a predetermined period of time, a third motor driven,

ing device adapted to be set into operationby said third.

timing device when said first and third timing devices are performing a @cycle of operations concur rently I ing device for closing a circuit when a predetermined number ofpairs of .signals have been counted thereby, and means including said circuit closing means for firing said detonating means in response to. the second signalot the nextsu cceeding pair of signals received by the signal receiving meansv during a subseq uent cycle of operations of said, first timing, device.

8. In a system for firing 'a' mine in response to aipredetermined number of pairs of signals received through the surrounding water in predetermined time spaced relation, each of said pairs of signals comprising signals for receiving said pairs of. signals, said relay having a contact element movable from an initial unoperatedposition to either one of two circuit closing positions selectively in accordance with the polarity of each of said signals received by said signal receiving means, a pair of motor driven timing devices adapted to be set into operation selectively in accordance with the movement of said contact element to one of said two circuit closing positions thereby initiating a cycle of operations of one of said pair of timing devices, a third motor driven timing device having control means including a plurality of circuit closing devices for restoring said contact element to said initial unoperated position and for rendering said relay unresponsive to signals for a pre determined interval of time, means controlled by at least one of said pair of timing devices for initiating a cycle of operations of said third timing device during a cycle of operations of said one of said pair of timing devices, electroresponsive detonating means, a counting device adapted to be set into operation while said pair of timing devices are performing a cycle of operations concurrently thereby to count the number of said pairs of signals received by said signal receiving means, means included in said counting device for closing a circuit when a predetermined number of pairs of signals have been counted by said counting device, and means including said circuit closing means for firing the detonating means while said pair of timing devices are performing a cycle of operations concurrently in response to the next succeeding pair of signals received by said signal receiving means.

9. In a mine firing mechanism of the character disclosed, a signal detecting device, a sensitive relay having a contact element movable to an initial unoperated position and to a circuit closing position, means controlled by said signal detecting device for moving said contact element tosaid circuit closing position as a signal is detected by the detecting device, a timing device, means controlled by said relay for initiating a cycle of operations of the timing device as said contact element is moved to said circuit closing position, means included in said timing device and eflfective while the timing device is in operation for rendering said detecting device ineffective for a predetermined period of time during said cycle of operations, and means controlled by said timing device for momentarily restoring said contact element to said initial unoperated position while the detecting device is rendered ineflective.

10. In a mine firing mechanism of the character disclosed, signal receiving means, a relay adapted to be operated by said signal receiving means as a signal is received thereby, a rotatable timing device operable in unit cycles, said timing device having included therein a plurality of pairs of contacts adapted to be operated in predetermined sequential order, an operating circuit for said timing device, means controlled by said relay for closing said circuit thereby to initiate a cycle of operations of said timing device as the relay operates, means on said relay and controlled by one of said pairs of contacts on said timing device for momentarily restoring the relay to an initial unoperated position during a cycle of operations of the timing device, manually settable resistance means included in said operating circuit and adapted to maintain the timing device in operation for a predetermined period of time, and a second pair of said contacts on said timing device for rendering said relay unresponsive for said period of time to signals received by said signal receiving means during a cycle of operations of the timing device.

11. In a counting device of the character disclosed comprising substantially an electric motor adapted to be operable in unit cycles thereby to operate a plurality of cam controlled electrical contacts in predetermined sequential order, the improvement lying in the provision of; a mine casing, a tens switch and a units switch disposed within the casing, each one of said switches having a switch arm adapted to engage a plurality of switch contacts in succession, means including a Geneva movement on the counting device for causing the switch arm of said units switch to be moved into engagement with the next succeeding switch contact thereof while the counting device is performing a cycle of operations, means including a second Geneva movement on the counting device for causing the switch arm of said tens switch to be moved into engagement with the next succeeding switch contact thereof as the switch arm of said units switch engages the tenth switch contact thereof, a pair of manually settable switches disposed within said mine casing, said pair of manually settableswitches comprising a units switch and a tens switch element adapted to be moved into engagement selectively with a plurality of contacts and indicia therefor, andan electrical channel for maintaining an electrical connection between said first and second named pairs of switches whereby a circuit is closed by said switch arms when the switch arms have engaged a pair of contacts respectively corresponding to the settings of said manually settable switches. V

12. In combination, signal receiving means, a relay, means controlled by said signal receiving means for causing said relay to operate when a signal is received by the signal receiving means, a normally inactive counting device operable in unit cycles, said counting device having a motor operatively connected thereto, a source of electrical power, means controlled by said relay for connecting said source of power to said motor when the relay operates thereby tooperate the motor and initiate a cycle of operations of said counting device, means included in the counting device for maintaining said motor in operation for a predetermined period of time, and means on said counting device, for rendering said relay unresponsive to signals received by the signal receiving means during said predetermined period of time. t

13. In a firing mechanism of the character disclosed, in combination, a signal detecting device, a relay adapted to be operated by said signal detecting device, a pair of normally inactive motor driven timing devices, means controlled by said relay for initiating a cycle of opera tions of one of said timing devices as the relay operates, means controlled by the operated one of said timing devices for initiating a cycle of operations of the other timing device during a cycle of operations of said operated timing device, means including a pluralityof circuit controlling elements on Said other timing device for restoring the relay to an initial unoperated condition during a cycle of operations of the other timing device, means on said other timing device and effective concurrently with the restoring means for rendering said relay unresponsive for a predetermined period of time to signals detected by said signal detecting device, a counting device, means controlled by said one of said timing devices for initiating a cycle of operations of the initiating a cycle of operations of the counting device, detonating means, a firing circuit including the detonating means, and means on said counting device for rendering said firing circuit effective when the counting device has performed a predetermined number of cycles of operations. I

14. In a marine mine, a mine casing, a normally inactive motor driven counting device, disposed within said casing and adapted to operate in unit cycles, said counting device comprising a rotatable cam member adapted to ac-. tuate a plurality of circuit closing elements in predetermined sequential order, means controlled by a signal received through the surrounding water for initiating a cycle of operations of said counting device, means including said plurality of circuit closing elements for maintaining said thereof has been completed, a speed reducing mechanism 19 adapted to move said cam member through'one revolution during a cycleiof operations of said counting device, ajpair of switches on the counting device, one of said switches being. atensswitch and the second a units switch, a pair of manually settable switches arranged within the casing'adaptedto be set at will to the tens and units digits respectivelyof the number corresponding to the desired number of signals to be counted by said counting device, means including a Geneva movement for causing said first named units'switch to move through a fractional portion of a revolution as said cam member completes a revo1u tion, means including a second Geneva movement for causing said first named tens switch to move through a fractional portion of a revolution when said first named units switch has completed a revolution, a firing circuit including'said pairs of switches, and means controlled lay-said tens and said units switches for rendering said firing circuit eifective when said counting device has completed a number of cycles of operations corresponding to thenumber set up on said pair of manually settable' switches.

l5.-In a system for firing a mine in response to a predetermined number of pairs of signals receivedthrough the surrounding water in predetermined time spaced relation,.said pairs of signals comprising signals of like and unlike polarity respectively, a mine casing, signal receiving means including a relay arranged within said casing, a pair of-normally inactive motor driven timing devices adapted to be operable in unit cycles, each ofsaid timing devices comprising a plurality of cam actuated electrical contacts adapted to be operated in predetermined sequential order, means controlled by said relay for initiating a cycle ofoperationsof said each of said timing devices in succession inresponse to a pair of signals received by said signal receiving means, a third normally inactive'motor driven timing device adapted to perform cyclic operations, said third timing device having a plurality of cam controlled electrical contacts to be operated in predetermined sequential order, contact means included in each of said pair-of timing devices and adapted to set the third timing device in operation during a cycle of operations of either one of said pair of timing devices, contact means included in said third timing device and adapted to maintain the third timing device in operaton until a cycle of operations thereof has-been completed, avar'iable resistor connectedto said contact means and settable at will to diflerentsettings for varying the speed of said motorthereby to control the time'required to complete a cycle of operations-of the third timing device, means including additional contact means on said third timing device adapted to restore said relay to an initial responsive condition and to render the relay unresponsive for a predetermined period of time to signals received by 'said signal receiving means during a-cycle of operations of the third timing device, a motor driven counting device adapted to operate in unit cycles, said countingdevice having a plurality of manually settable switches disposed within the mine casing for selecting the number of pairs of signals to be counted by the counting device, contact means included in each one of said pair of timing devices for initiating a cycle offloperations of said counting device when said timing devices are performing a cycle of operatons concurrently, a pair of contacts included in said counting device adapted to render said signal receiving means ineffective during acycle of operations of the counting device, electroresponsive detonating means,-a firing circuitincluding said detonating means, means included in said counting device for closing in part said firing circuit when the counting device has counted a predetermined number ofpairs of signals received'by said signal receiving means in said predetermined time spaced relation, and means including said circuit closing means for completely closing'said firing circuit when said pair-of timing devices perform a cycle of operations concurrently in response to the next succeeding pair of signalsreceived byi-said sign l-receivingymeans,

16... In a mine :firing mechanism. of the character closed, va signal detecting device, a relay havingapair of no'rniallyQopen contactstadapted to beclos e d-as the relay operates, means controlled bysaid signal detecting device for operating the relay as alsignal is detectedbyrthe detecting-device,-a timing device, means controlled by said relay for initiating a cycletof operations of the timing device as thecontacts of the relay are closed, means included in said timing device for disconnecting the detecting device from said relay rendering the vdetecting device ineffective to operate said relay for a predetermined period of time during said cycle of operations, and means controlled by the. timing device for momentarily disengaging said relay, contactswhile the detecting device is rendered ineffective.

'17. In amine-firing mechanism of the character, disclosed, the combination of atsignal detecting device, a relayhavinga pair ofnormally open contacts adaptedjo be engaged as the relay operates, means controlled by said signal detecting device for operating the relay as a signal is detected by the detecting device, a timing device, means controlled by the relay for initiating a cycle of operations of the timing device as said contacts are engaged, means included in said timing device for rendering said, detecting device ineffective for a predetermined period of timeduringsaid cycle of operations, means controlled by the timing device for momentarily disengaging said contacts while the detecting device is rendered ineflfective, and means including an. inertia responsive element for setting said timing device in operation thereby to prevent said contacts from being brought into engagement as a shock is received by the mechanism.

18. In a mine firing mechanism ofthe character disclosed, a signal detecting device, a sensitive relay having a contact element movable to an initial unoperated position and to a circuit closing position, means controlled by said signal detecting device for moving the contact element to said circuit closing position as a signal is detected by the detecting device, a control circuit connectedlto said contact element, .a timingdevice, means including said control circuit for initiating a cycle of operations of the timingdevice as the contact element is moved to said circuit closingposition, means included in said timing device and, effective while the timing device is in operation for rendering said detecting device ineifective for a predetermined period of time during said cycle of operations, means controlled by said timing device for momentarily restoring said contact element tosaid initial unoperated position while the detecting device is rendered ineffective, a second relay having a pair of normally closed contacts included in said, control circuit for interrupting the control circuit as the relay operates, and inertia controlled circuit closing means for operating said second relay as a shock is received by the mechanism.

7 19. In a mine firing mechanism of the character disclosed,a, signal detecting device, a'sensitive relay having a contact elementmovable to anoinitial unoperated posi-- tion. and to a, circuit closing position, means controlled by-said signal"detecting-device for moving the contact element to, said circuit closing position as a signal is detected byatherdctcctingtdevice, a control circuit con- I nectedto said contact clement, a timing device, means includingsaid control circuit for initiating a cycle of operations of the, timing'device as thec'ontact element is moved to said circuitclosing position, ,means included in said-timing device-and, ,efiective whilethe timing device isinoperat-ion, for rendering said detecting wdevice ineiiectivefor apredetermined period ofotime dnringsaid cycle of oper ations,,means controlled by said timing device for,momentarilyfrestoring said contact elementto said initialunoperatedposition while the, detecting device is rendered.ineifective, .,a second relayhaving ,a pair of normally closed contacts included in said controlcircuit for. interrupting the control circuit as the. relayopcn ates, inertia controlled: circuit closing means for ,operat 21 22 Y ing said second relay as a shock is received by the mecha- References Cited in the file of this patent nisrn, a source of power, and means on said second relay for connecting said timing device to said source of power UNITED STATES PATENTS as the second relay operates thereby to operate the timing 1,364,615 Cruz I an. 4, 1921 device and prevent said contact elements from moving 5 ,390,768 Dorsey Sept. 13, 1921 to said closing position in response to said chock. 1,491,004 Dllflie Apr. 22, 1924 i i i