US3440926A - Control circuitry for automatically operated guns - Google Patents

Description

R. J. GURA ET AL INVENTOR5 g? Eon/A20 G. A OD/ A z 5 ATTORNEYS A m G x J Q l u A r /T w v w E Q i 4i 4. 1 3 E w 1. I 1 iv M. Q x

April 29, 1969 CONTROL CIRCUITRY FOR AUTOMATICALLY OPERATED GUNS Filed Dec. 4, 1967 April 29, 1969 R. GURA ET AL CONTROL CIRCUIIRY FOR AUTOMATICALLY OPERATED GUNS Sheet Filed Dec. 4, 1967 Z ATTORNEYS A ril 29, 1969 R- J R ET AL 3,440,926

CONTROL CIRCUITRY FOR AUTOMATICALLY OPERATED GUNS Filed Dec. 4, 1967 Sheet 4 of 4 Lez (RH xv M4 M7 L /9/ I X D/ 0 WARD G. A aom A H Y w ATTORNEYS I N VEN TO/Q5 3,440,926 CONTROL CIRCUITRY FOR AUTOMATICALLY OPERATED GUNS V 7 Robert J. Gura, Lyndhurst, and Edward G. Hodina,

Willoughby, Ohio, assignors to TRW Inc., Cieveland, Ohio, a corporation of Ohio Filed Dec. 4, 1967, Ser. No. 687,708 Int. Cl. F41d 7/02 US. Cl. 89-135 10 Claims ABSTRACT OF THE DISCLOSURE An electrical control circuit for firing machinegun. The control circuit incorporates solid state electronic components to generate firing rate impulses which are used to operate an electro-mechanical actuating device which, in turn, operates the necessary mechanism to fire the machinegun. The machinegun includes a feed selector which is used to position one of a pair of feed trays against the gun so that the type of ammunition in the feed tray placed thereagainst will be fired. Also associated with the machinegun is a charger actuator which includes an electric motor and a gear train to retract the bolt carrier to the seared position. Also associated with the charger actuator is an electromagnetic clutch and a limit switch for actuating indicating means. By incorporating electrical, rather than manual, control functions of the machinegun it may be positioned in one place and operated by a remote control unit which is positioned in another place not hazardous to personnel.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to means for controlling the firing of a gun, and more particularly to an electrical control circuit to control the firing of a machinegun. Specifically, the present invention is directed to a unique and novel arrangement of solid state electronic components which are used to provide a plurality of preselected firing rate control signals which, in turn, are used to energize a gun solenoid to fire the gun.

Description of the prior art Heretofore, automatic machineguns, for example of the 20 mm. cannon type usually included only two modes of operation, a semi-automatic load and a full automatic load. A mechanical switching mechanism is used to select either one of the two modes. However, it is found advantageous to provide a plurality of modes, for example, several different firing rates which fall between the semiautomatic mode and the firing rate of the fully automatic mode. That is, should an automatic gun have a maximum firing rate of 500 rounds per minute in the fully automatic position, it may be desirable to fire the gun at a rate of, for example, 1 to 200 rounds per minute, to obtain the greatest effectiveness of the machinegun when firing the gun at difierent types of targets.

However, it is very ditficult to vary the firing rate of a machinegun by varying mechanical or manual control functions. Furthermore, a mechanical or manual device 3,440,926 Patented Apr. 29, 1969 would require that personnel be stationed immediately ad acent the gun to operate the gun.

SUMMARY OF THE INVENTION Accordingly, one of the primary objects of the present invention is to provide a control system for automatically controlling the operation of a machinegun by electrical impulses rather than mechanical or manual control functrons.

Another object of the present invention is to provide an electrical control circuit for controlling the firing of a machinegun which circuit includes means for selectively changing the firing rate of the gun to any one of a plurality of preselected firing rates.

Yet another object of the present invention is to provide a control circuit for firing a machinegun which can be easily mounted in a remote control box equipped with indicating lamps to indicate the various conditions of the gun, thereby allowing the machinegun itself to be positioned at one location and the remote control box to be positioned at another location.

Still another object of the present invention is to provide a control circuit which is extremely simple and etficient for controlling the firing rate of a machinegun under all adverse environmental condi.ions.

Briefly, the electrical control components include a firing solenoid which permits the gun to be fired in response to an electrical input signal. A feed selector actuator is provided to position one of a pair of ammunition feed trays against the gun for the selection of the desired type of ammunition. A charger actuator is used to retract the bolt carrier of the gun to the seared position. A round of ammunition is placed in the firing position by positioning the round to the top of the feed tray which is against the gun when the bolt is in the seared position. A round positioning switch senses the presence of the ammunition in the firing position. When the bolt carrier is released by a firing signal the round of ammunition is picked up by the bolt carrier as it moves forward, and the round is driven into the barrel and fired by the action of the firing pin at the completion of this action. The bolt carrier is automatically returned to the seared position by the recoil of the gun. As the bolt returns to the seared position, it actuates feed paws which move the next round of ammunition in the tray against the weapon to the firing position. Control of all of the electrical components of the firing system of the machinegun is accomplished by the control circuit which may be mounted within a master control box remote from the gun.

Other objects and features will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings in which like reference numerals throughout the various views of the drawings are intended to designate similar elements or components.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a top cross sectional view of a machinegun operated in accordance with the principles of this invention and shows a pair of feed trays positioned on either side of the gun;

FIGURE 2 is a side elevational sectional view of the 3 machinegun of FIGURE 1 with the bolt carrier in the seared position;

FIGURE 3 is a side elevational sectional view of the machinegun of FIGURE 1 showing the bolt carrier moving forward and inserting a round of ammunition in the breech of the gun;

FIGURE 4 is a schematic block diagram showing the firing rate selector circuitry used to operate the machinegun of FIGURE 1;

FIGURE 5 is a portion of a detailed schematic diagram illustrating the preferred circuit arrangement of the control circuitry of the present invention; and

FIGURE 6 is a corresponding mating portion of the schematic wiring diagram of FIGURE 5 showing the preferred circuit arrangement of the control system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Seen in FIGURES 1, 2 and 3 is a machinegun which is operated in accordance with the principles of this invention as is designated generally by reference numeral 10. The machinegun 10 includes a barrel 11 surrounded by a sleeve 12. An ammunition chamber 13 is formed at the receiving end of the barrel to receive a round of ammunition, indicated generally by reference numeral 14.

A feed selector tray 16 is shown positioned against the side of the gun 10 to allow the ammunition therein to be stripped off the ammunition belt and delivered to the ammunition chamber 13. A second feed selector tray 17 is shown positioned away from the side of the gun thereby preventing the ammunition therein from being fed to the gun. The feed tray 16, for example, may carry armor piercing ammunition while the feed tray 17 may carry high explosive ammunition. Therefore, the type of ammunition fired by the machinegun is selected by moving the appropriate feed tray in position against the side of the machinegun. The feed trays 16 and 17 are pivotally secured to the gun near the receiving end of the barrel 11 by a pair of pins 16a and 17a respectively. The feed tray 17 has connected thereto a lever 18 which, in turn, is pivotally connected to a pin 19a secured to a boss 19. The boss 19 is fastened to the rear housing 20 of the machinegun 10. The lever 18 is provided with a grip portion 21 to provide means for manual movement of the feed tray 17. The feed tray 17 is linked together with feed tray 16 by a link 22, which is shown partially broken away. The link 22 causes both feed trays 16 and 17 to be moved by movement of the pivot 18.

To select the ammunition from the feed tray 16, the grip 21 of lever 18 is moved fully toward the side of the gun which, in turn, pulls feed tray 17 away from the gun and feed tray 16 in contact with the gun. On the other hand, selection of the ammunition in feed tray 17 is obtained by pulling the grip 21 of lever 18 fully away from the machinegun thereby placing feed tray 17 against the side of the gun and pushing feed tray 16 away from the Weapon. It will be understood that an intermediate position is obtainable thereby causing both feed trays 16 and 17 to be away from the sides of the gun to prevent ammunition from either tray from being fed to the chamber 13.

According to the present invention, an automatic feed selector mechanism 23 is mounted on the side of the rear housing 20 just rearward of the feed tray 16. The feed selector 23 includes a drive motor 24 secured to a housing 25 which contains a suitable gear reduction therein to cause rotation of a pivotal shaft 26. A link 27 is connected to the shaft 26 and to the rearward end of the feed tray 16. Therefore, actuation of the drive motor 24 to cause preselected angular rotation of the shaft 26 will operate the feed trays 16 and 17 in the same manner as the manual grip 21 of lever 18.

A charger actuator designated generally by reference numeral 29 is also mounted on the rear housing 20 rearward of the feed selector 23. The charger actuator 29 includes a drive motor 30 secured to a gear housing 31. Secured to the drive motor 30 is a plug receptacle assembly 32 for receiving the necessary control cables to operate the charger actuator. Similarly, the feed selector mechanism 23 includes a plug receptacle 28 for connection thereto of the appropriate control cables for operation thereof. The charger actuator 29 operates a bolt carriage 33 which, in turn, carries a sear 35 for stripping off and 'firing the rounds of ammunition.

Positioned within the housing 31 of the charger actuator is an electromagnetic clutch and a limit switch. When power is applied to the charger actuator, the clutch is energized to couple the drive motor 30 to the output shaft of the gear train within the housing 31. The output shaft is connected to a chain (not shown) which retracts the bolt carrier 33 until the bolt carrier reaches the seared position, as shown in FIGURE 2. When the bolt carrier 33 is in the seared position it actuates a lever which, in turn, controls switch means to deenergize the electromagnetic clutch connecting the motor 30 to the output shaft of the housing 31. Also, when the bolt carrier 33 is in the seared position a limit switch is actuated to energize a lamp to provide a visual indication that the bolt carrier is in the seared position. As the motor 30 is decoupled from the output shaft by deenergization of the electromagnetic clutch, the motor will continue to run until power is removed therefrom.

The bolt carrier 33 is held in the seared position by a sear 35 cooperable with a trigger 36, as best seen in FIG- URE 2. When the trigger 36 is actuated the sear 35 is moved out of engagement with a notch 33a of the bolt carriage 33 thereby allowing the bolt carriage to be driven forward by a drive spring 37. After the bolt carrier 33 has stripped off a round of ammunition and fired it the bolt carrier is moved rearwardly by the recoil action of the gun. To dampen the stopping inertia of the bolt carrier 33 the bolt carrier engages a buffer plate 38 which protrudes from a housing 39. The buffer plate is urged outwardly toward the bolt carrier by means of a compressed spring 40 which is held compressed in the housing by a bolt 41 threadedly engaging the rearward wall of the housing.

Mounted at the rear portion of the gun housing 20 is a solenoid 43 which includes an actuating plunger 44 extending therefrom. The plunger 44 engages the trigger lever 36 to cause movement of the trigger lever and release the bolt carrier 33 from the seared position.

According to the present invention, the firing solenoid 43 is energized either by a single electrical pulse to cause a single firing of the gun or by a series of pulses at a predetermined pulse rate to cause rapid firing of the gun at a controlled firing rate less than the maximum mechanical automatic firing rate of the machinegun.

For a better understanding of the control circuitry used to control the firing rate of the gun 10, reference is now made to FIGURE 4. The control circuitry shown in FIGURE 4 may be housed in a remote control unit positioned in a convenient location to enable operation of the gun by personnel not in the vicinity of the gun. The control circuit includes a line 50 which is connected to a terminal G which may be mounted on a terminal board and connected to a voltage source. The line 50 includes a fire signal switch 5011 which is closed when firing of the machinegun is desired.

A ground lead 51 provides a common ground between the electrical components of the weapon with that of the electrical components of the fire control circuit. Terminal A is connected to a line 52 for supplying 24 volt direct current power to the control circuit of FIGURE 4. Also, terminal D is connected to a line 53 for receiving electrical pulse signals from the control circuit to energize the firing solenoid 43, of FIGURES 1, 2 and 3, at the desired firing rate.

A rate selector switch 55, is shown as having switch banks 55a and 55b which are ganged together to a common selector knob. By selecting a rotary switch of the double wafer type, the circuitry and wire connections of the control circuit is somewhat simplified. However, it will be understood that any type of selector switch will function equally well. The rate selector switch 55a has a plurality of stationary contacts connected to a unijunction transistor oscillator circuit 56. Also connected to the oscillator 56 is a plurality of contactors 57, 58 and 59. The contactors 57-59 are energized in certain modes of operation, and deenergize in other modes of operation, to place the oscillator 56in operation only during selected controlled firing rates of the machinegun. The contactors 57-59 are electromagnetically coupled to an energizing coil 60 which is connected to certain ones of a plurality of stationary contacts of the selector switch 55b. Therefore, when the 'selector switches 55a and 55b are, for example, in the 100 or 200 rounds per minute position, the coil 60 is energized thereby closing the contacts 57 and 58 and opening the contact 59.

The pulse signal information generated by the unijunction transistor oscillator circuit 56 is delivered to an OR gate 61 through a line 62. Also connected to the OR gate 61 is a pulse forming network 63 which delivers singular pulses to the OR gate 61 through a line 64. The pulse gate 63 is operable only during the semi-automatic mode of operation of the control circuit.

The pulse output of the OR gate 61 is delivered to a one-shot multivibrator 66 which generates a square wave pulse having a fixed pulse width and a repetition rate which corresponds to the frequency of the output pulses of the unijunction transistor oscillator 56. The square wave pulses from the multivibrator 66 are delivered to an OR gate 67 through a line 68. Also connected to the OR gate 67 is the fire signal line 50 through the switch 55b and a line 69. When the selector switch is in the automatic position, the OR gate receives a continuous signal thereby maintaining the gun solenoid 43, in the energized condition to allow the machinegun to fire automatically at its maximum rate.

The square wave pulses from the multivibrator 66 or the continuous signal from the trigger line 50 pass through the OR gate 67 to a buffer amplifier 70 via a line 71. The buffer amplifier 70 serves as an isolation stage between the output of the OR gate 67 and the input of a following AND gate 72.

The AND gate 72 receives signal information from both the buffer amplifier 70 and the trigger line 50. When the AND gate 72 senses the presence of a control signal from both the trigger line 50 and the buffer amplifier 70, an output signal is applied to a relay driver amplifier 74 through a line 76. The relay driver amplifier 74 may be a power transistor stage incorporating one or more transistors to energize a relay coil 77 connected thereto. One end of the relay coil 77 is connected to a line 78 which, in turn, is connected to the line 52 for receiving 24 volt DC power therefrom. Connected at the junction of the relay coil 77 and the line 78 is a contactor 79. The contactor 79 is actuated by energization of the relay coil 77, and closure of contactor 79 will apply an electrical pulse signal to terminal D through the line 53. This action will energize the gun solenoid 43 for a short period of time sufiicient to fire the gun.

Connected in shunt with the contactor 79 is an arc suppressor circuit 80. The are suppressor circuit 80 may be of any conventional type, for example, one or more capacitors, or a breakover diode which is used for are suppression.

To insure that the power applied to the control circuit of FIGURE 4 is maintained at a predetermined fixed value, a voltage regulator and filter circuit 85 is connected between the 24 volt power line 52 and the ground line 51. The regulation and filter circuit prevents variation in the DC supplied voltage from affecting the operation of the control circuit. Also, the filtering circuit is added to insure that noise pulses on the power line will not produce erratic behavior of the control circuit. The contactor 79 is connected directly to the 24 volt DC power source to insure that full power is applied to the firing solenoid 43. The are suppression circuit 80 is utilized to reduce extraneous electrical noise pulses which may be generated by opening and closing of contacts 79.

With the selector switch in the semi-automatic position, the unijunction transistor oscillator is not operative due to the condition of contactors 57, 58 and 59. A trigger signal applied to the line 50 will apply a signal pulse to the one-shot multivibrator 66 through the pulse network 63 and the OR gate 61. The multivibrator 66 will develop an output pulse of the proper time duration. This pulse then passes through the OR gate 67 and is amplified by the buffer amplifier 70. The output signal of the amplifier ..70 is then delivered to the AND gate 72. The AND gate 72 is used to insure that both the signals from the trigger switch 50a and from the multivibrator 66 are present before the weapon is fired. Finally, the pulse passes through the AND gate 72 and is delivered to the relay driver 74 which, in turn, energizes the relay coil 77 to close the contactor 79 and cause firing of the gun. It will be understood that no further firing will occur until the trigger switch 50a is released and pressed again.

To fire the machinegun at preselected firing rates, the trigger signal will energize the relay coil 60 thereby actuating the contactors 57-59 to place the unijunction transistor oscillator 56 in operation. The pulse signal information from the oscillator 56 is delivered to the OR gate 61 whereupon the pulses will follow the same path as for semi-automatic operation to produce a series of electrical pulses to energize the firing solenoid 43.

For a better understanding of the various components of the control circuit shown in FIGURE 4 and the operation of the electro-mechanical control devices shown in FIGURE 1, reference is now made to FIGURES 5 and 6 which shows the detailed schematic diagram of the control circuit used to control the operation of a machinegun in accordance with the principles of this invention. The control circuit of FIGURES 4 and 5 includes a terminal block which may be formed of a plug 91 and a receptacle 92. A 24 volt source is connected to terminal A and therefrom to a main switch 93 which applies power to the control circuit and energizes an indicating lamp 94 to give visual indication that power is so applied. When switch 93 is closed power is also applied to terminal E of the terminal block and therefrom to one side of switches 96 and 97. The other side of switches 96 and 97 are connected to terminals F and G and therefrom to indicating lamps 98 and 99 respectively. Switches 96 and 97 sense the presence of a round of ammunition in the top position of the feed tray and give an indication of such presence of ammunition by energizing lamps 98 and 99.

Power from terminal A of terminal block 90 is applied to the firing rate control circuit and to other control switches and relays as will be more fully realized from the following description. The firing rate control circuit is indicated generally by reference numeral 100 and includes a current limiting resistor 101 in series with a voltage regulator network defined by a reference diode 102 and a plurality of capacitors 103, 104- and 105.

The unijunction transistor oscillator 56 receives power from the voltage regulator network and includes a voltage divider comprising resistors 106 and 107 connected to the emitter of a unijunction transistor 108. Relay contactors 58 and 59 are connected in series between the junction of resistors 106 and 107 and the emitter of transistor 108. A charging capacitor 109 is connected between relay contactors 59 and 58 for receiving charging current through resistor 106 when contactor 59 is closed.

Also connected to the junction between relay contactors 58 and 59 is a pair of resistor circuits 110 and 111 which are connected to stationary contacts of selector switch 55a. Relay contactor 57 is connected in series with the resistor networks 110 and 111. By placing the selector switch 55a in connection with one of the resistor networks 110 and 111, the frequency of oscillation of the unijunction transistor circuit is changed in response to the resistance value of the network connected thereto.

The unijunction transistor 108 is connected in series with a pair of resistors 112 and 113 so as to produce out put pulses across resistor 113 during oscillation of the circuit. The output pulses are applied to the OR gate 61 through a resistor 114 and a capacitor 116. The pulse delivered through capacitor 116 is developed across a resistor 117 to forward bias a diode 118 to change the operating state of the one-shot multivibrator 66. The OR gate 61 includes a second diode 119 which is connected in series with the pulse forming network 63 and to the semi-automatic position of selector switch 5511. Therefore, as mentioned hereinabove, either a pulse from the unijunction oscillator 56 or a pulse from the pulse forming network 63 will produce a control signal to fire the gun.

The one-shot multivibrator circuit 66 includes a pair of transistors 120 and 121. The base electrode of transistor 121 is connected to the positive voltage source through a potentiometer 122 and a diode 123, and the collector electrode of transistor 121 is connected to the positive voltage source through a resistor 124. The base electrode of transistor 120 is connected to the positive voltage source through resistor 124 and a resistor 126. The collector of transistor 120 is connected through a resistor 127 and therefrom to the positive source. A capacitor 128 has one end thereof connected to the junction of resistor 127 and transistor 120 and the other end thereof connected to the junction of potentiometer 122 and diode 123. The base electrode of transistor 120 is connected to ground potential through a resistor 129, while the base electrode of transistor 121 is connected to ground potential through a resistor 130. The emitter electrodes of transistors 120 and 121 are connected together and to ground potential through a resistor 131.

The components of the one-shot multivibrator 66 are sized such that upon applying power to the multivibrator transistor 121 is rendered conductive while transistor 120 is maintained in the nonconductive state. This action insures that no output pulse from the multivibrator will be applied to the OR gate 67. A pulse from the output of the OR gate 61, to the base electrode of transistor 120 will render transistor 120 conductive thereby applying a negative pulse to the base of transistor 121 through the capacitor 128 and diode 123. Therefore, transistor 121 is rendered non-conductive thereby applying a forward bias to diode 132 sulficient to cause conduction of the reference diode 136.

When the selective switch 55b is in the full automatic position, a diode 133 of OR gate "67 is forward biased through a resistor 134 which also causes sufiicient voltage to be applied to the cathode of reference diode 136 to cause conduction thereof. The output of reference diode 136 is developed across a pair of resistors 137 and 138.

The signal information developed across resistor 138 is delivered to the buffer amplifier 70 which includes a pair of transistors 139 and 140. The collector of transistor 139 is connected to the base of transistor 140 through a resistor 141 and a diode 142. The buffer amplifier 70 is so arranged that transistor 140 is conductive and transistor 139 is non-conductive when power is applied to the circuit and no fire control signals from the trigger circuit are supplied. Therefore, pulse signal information to fire the gun causes transistor 139 to be rendered conductive which, in turn, renders transistor 140 non-conductive to produce a positive output pulse at the collector electrode thereof.

The positive output pulse is delivered to a diode 143 which forms part of the AND gate 72. Also associated with diode 143 is a diode 144 which is connected to the trigger terminal D of terminal block 90 through a resistor 150. The anodes of diodes 143 and 144 are connected together and to the cathode of a reference diode 146 and a voltage developing resistor 147. The cathode of diode 143 is also connected to ground potential through a resistor 148, while the cathode of diode 144 is connected to ground potential through a resistor 149. The collector load resistor of transistor has an ohmic value which is less than resistor 148 such that when transistor 140 is rendered non-conductive the voltage developed across resistor 148 reverse biases diode 143. However, the ohmic value of resistor 149 is less than the ohmic value of resistor 147 so that the voltage developed at the junction of reference diode 146 and resistor 147 is below the reference voltage necessary to render the diode conductive. However, a control signal from the trigger switch applied to the cathode of diode 144 reverse biases the diode and the entire supply voltage is impressed at the cathode of reference diode 146. This action renders the reference diode 146 conductive.

The current passing through reference diode 146 is applied to the relay driver circuit 74 which includes a pair of transistors 151 and 152 connected in cascade for current amplification. When transistor 152 is rendered conductive relay coil 77 is energized to close contactor 79 which is connected to terminal C of the terminal block 90. Connected in parallel with transistor 152 is a reference diode 153 which, for example, may have a breakover voltage of approximately 36 volts to prevent transient voltages developed by the relay coil 77 from damaging transistor 152.

It will be understood that pulse signal information from the unijunction oscillator circuit 56 or from the semi-automatic pulse, when switch 55 is in the semi-automatic position, will produce a voltage across the relay coil 77 to cause firing of the gun. Furthermore, although only two preselected firing rates are shown by resistor networks 110 and 111, it will be understood that the control circuit of the present invention may incorporate as many resistor networks as desired to operate the machinegun at as many different firing rates as desired.

In the fully automatic position of switch 55, signal voltage is applied continuously to diode 133 of the OR gate 67 and to diode 144 of AND gate 72. This action will cause relay coil 77 to be continuously energized thereby maintaining contactor 79 closed and continuously energizing the fire solenoid, 43 of FIGURES 1-3. In the full automatic position the gun will fire at its maximum capable firing rate.

Also associated with the control circuit of FIGURES 5 and 6 are a plurality of selector switches 160, 161 and 162. Each of the switches -162 is connected to a common line 163 which, in turn, is connected to the 24 volt power supply through the main switch 93 and terminal A of the terminal block 96. The other end of switch 160 is connected to terminal L of terminal block 90 and therefrom to a series connected limit switch 164. When switch 160 is closed, the actuator drive 23 of FIGURE 1, is energized to move the left hand ammunition tray into position against the gun. When the tray is in position, switch 164 opens to deenergize the drive motor of the actuator drive 23.

The other end of switch 161 is connected to terminal N of the terminal block 90 and therefrom to a series connected switch 166. When switch 161 is closed, power is supplied through switch 166 to the actuator drive motor 24 to position the right hand feed tray against the gun. When the feed tray is in position, switch 166 opens to deenergize the drive motor of the actuator drive unit 23. To position the feed trays 16 and 17 in the neutral position, switch 162 is energized thereby energizing a relay coil 167 to close the contactor 168 associated therewith and apply power to terminal M of the terminal block 90 and therefrom to the drive motor 24 through a series connected limit switch 169. A capacitor 176 is connected in parallel with contactor 168 to provide arc suppression means thereby reducing wear of the contactor due to arcing.

A plurality of normally open switches 171, 172 and 173 are connected to terminals P, Q, and R respectively of terminal block 90 and therefrom to indicator lamps 174, 175 and 176. Switches 171-173 are actuated in response to the position of the actuator drive 23. Therefore, when the actuator drive 23 moves the right hand feed tray in position against the gun, switch 171 is closed to energize the lamp 174 to give a visual indication that the feed tray is in position. Similarly, when the left hand feed tray is in position against the gun, switch 173 is closed to energize lamp 176. When neither feed tray is against the gun, the feed trays are in the neutral position, switch 172 is enclosed to energize lamp 175 to indicate this condition.

The junction of lamp 176 and switch 173 is connected to the anode of diode 177 which, in turn, has the cathode thereof connected to a normally open switch 178 and a normally closed switch 179 through the terminal I of terminal block 90. The junction of lamp 174 and switch 171 is connected to the anode of a diode 180 which, in turn, has its cathode connected to a normally open switch 181 and a normally closed switch 182 through terminal I of terminal block 90. Similarly, the junction of lamp 175 and switch 172 is connected to the anode of a diode 183 which has the cathode thereof connected to switches 179 and 182 through terminal K of terminal block 90 and to the charge control switch 184 through a line 186.

Charge switch 184 is a double pull switch having one portion thereof connected to a relay coil 187 and the other end thereof connected to a relay coil 188. Relay coil 188 forms part of a latching relay 190 which includes a second relay coil 191 connected to the anode of diode 183. Diodes 177, 180 and 183 connected in circuit as shown in FIGURES and 6 provide means for a completely safe operation of a gun by eliminating the possibility of actuating the charger drive unit 29 when the bolt carrier 33 is in the forward position and a round of ammunition is in position in either one of the feed trays 16 or 17.

When the charge switch 184 is closed, relay coi- ls 187 and 188 are energized. Energization of relay 187 closes a contactor 192 which applies 24 volt power to terminal S of the terminal block 90 and therefrom to the charger drive unit 29. When the charger drive unit has retracted the bolt carrier and bolt to the seared position a switch 193, connected between terminals U and V of terminal block 90, is closed to energize a lamp 194 and give a visual indication that the bolt carrier is in the seared condition. A pair of capacitors 196 and 197 are connected in parallel with the contactor 192 to provide arc suppression means for the contactor.

The operation of a machinegun controlled in accordance with the principles of this invention is as follows: The gun is fired by releasing the bolt carrier 33 from the seared position. This can be accomplished manually by depressing of the trigger lever 36 or electronically by energization of the solenoid 43. The rate control circuit of FIGURES 5 and 6 apply power to the firing solenoid 43 in one of a plurality of modes of operation and selected by the rate selector switch 55. In the semiautomatic mode of operation, the rate control applies a single pulse of power to the firing solenoid when the trigger is pressed to release the bolt carrier 33. As long as the trigger remains depressed the solenoid remains unenergized to allow the bolt carrier to return to the scared position. Upon releasing the trigger the gun can be fired again by depressing the trigger and allowing a pulse to be generated by the pulse forming network 63.

In the fully automatic position, the rate control circuit applies continuous power to the solenoid 43 to maintain the solenoid energized thereby preventing the bolt carrier from being seared in position after firing of a round of ammunition thereby allowing the bolt carrier to return to the firing position at the natural rate of the machinegun.

To operate the machinegun at a controlled firing rate, less than the fully automatic firing rate of the machinegun pulses are applied to the firing solenoid 43 in response to pulses produced by the unijunction oscillator 56. Firing rates of and 200 rounds per minute are selected by the selector switch 55a thereby changing the resistance value in series with a charging capacitor of the oscillator circuit. It will be understood that any firing rate may be obtained by changing the resistance value in series with the charging capacitor and that more than two preselected firing rates may be provided. Control of the feed selector actuator 23 for positioning of the feed trays 16 and 17 is obtained by switches 160, 161 and 162, which may be push button type switches. Depressing switch or 161 applies power to the proper terminals of the feed selector actuator 23 of the proper polarity of DC voltage to drive the motor of the actuator. The motor 24 will continue to run until one of the limit switches 164, 166 or 169 opens to deenergize the motor when the feed trays are in the desired position On the other hand, one of the indicator switches 171, 172 or 173 is closed to energize one of the lamps 174, 175 or 176 to give visual indication of the position of the feed trays 16 and 17.

Depressing of switch 162 energfzes relay coil 167 to close contactors 168 associated therewith to apply power to the neutral position terminal of the drive actuator to position feed trays 16 and 17 in the neutral position. The limit switches associated with the feed selector actuator establish the proper terminal connections to the motor to apply the proper polarity of voltage to drive the motor to the neutral position irrespective of the position of the feed trays prior to depressing the neutral button 162.

To charge the gun, bring the bolt carrier 33 back to the seared position, ganged switches 184 are depressed. If feed trays 16 and 17 are in the neutral position, relay 187 is energized to close contactor 192 and apply power to the charger drive motor 30. This action will cause the charger actuator 29 to retract the bolt carrier 33 to the seared position. When the seared position of the bolt carrier is reached, a limit switch decnergizes a clutch associated with the charger actuator to disengage the drive motor from the output shaft. The drive motor will continue to run as long as the charge switch 184 is depressed.

The control circuit of FIGURES 5 and 6 also include provisions for preventing charging of the gun under improper conditions. Charging of the gun, as mentioned hereinabove, is permitted whenever the feed selector actuator is in the neutral position. Charging is also permitted when one of the feed trays is in posi ion against the gun and there is no round of ammunition in the top position of the tray against the gun. On the other hand, when a feed tray is in position against the gun and there is a round of ammunition in the top position, depressing of the charge switch 184 will energize the magnetic latching relay 190 to close the contactor 198a in parallel with the neutral selector switch 162 to energize relay coil 167, Therefore, contactor 168 is closed to energize the selector actuator and drive the feed trays to the neutral position. When the feed trays are in the neutral position, relay 190 resets to the initial condition and relay coil 187 is energized to close contactor 192 and drive the charge actuator 29. The circuitry used to accomplish the above logic sequence of operation incorporates the feed selector actuator position indicating switches 171, 172 and 173 together wi.h the ammunition position switches 96, 97, 178, 179, 181 and 182 and the diodes 177, and 183. Furthermore, it will be noted that the lamps 98, 99, 174, 175, 176 and 194 are of the push-t0-test type so that the lamp operation may be checked at any time.

Therefore, the control circuit of the present invention provides means for completely automatically controlling the operation of the machinegun from a remote control position in a completely safe and reliable manner. Although the preferred embodiment of the invention is shown and described in great detail, it will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

We claim as our invention:

1. A control circuit for firing a machinegun comprising:

solenoid means cooperable with the gun for causing firing of the gun when said solenoid means is in an energized state;

circuit means connected to said solenoid means to control the energization thereof;

a trigger including a triggering circuit connected to said circuit means to deliver thereto a first control signal responsive to the actuation of said trigger;

a rate selector circuit connected to said circuit means to deliver thereto a second control signal, said second control signal being a series of pulses indicative of the selected firing rate of the gun;

a rate selector switch connected to said rate selector circuit and positionable to select one of a plurality of predetermined firing rates, whereby said solenoid means is successively energized in response to said first and second control signals but at a rate indicative of said second control signal to fire the gun at one of said preselected firing rates, said rate selector circuit comprising a transistor oscillator circuit including a plurality of capacitor charge circuits connected between said transistor oscillator circuit and said selector switch, said selector switch placing a certain One of said capacitor charging circuits in circuit with said transistor oscillator circuit to set the firing rate of the gun; and

a one-shot multivibrator circuit connected between said transistor oscillator circuit and said circuit means to develop square wave pulses indicative of the output of said oscillator circuit to energize said actuator for a predetermined time during each firing of the gun.

2. A control circuit for firing a machinegun according to claim 1 wherein the transistor in said transistor oscillator circuit is a unijunction transistor.

3. A control circuit for firing a machinegun according to claim 1 further including an AND gate connected between said circuit means and said oscillator circuit and responsive to said first and second control signals to energize said solenoid means at a rate corresponding to said second control signal.

4. A control circuit for controlling the operation of a machinegun according to claim 1, wherein said machinegun includes a plurality of ammunition feed trays for delivering a different type of ammunition to the gun from each of the trays and further comprising means for positioning said feed trays in cooperable juxtaposition with said gun; and

an ammunition selector switch and circuit means electrically connected between the control circuit and said positioning means and selectively operable to actuate said positioning means to position a desired one of said feed trays to deliver to the gun a desired type of ammunition.

5. A control circuit according to claim 4 further including visual indicator means connected to said ammunition selector switch and circuit means to give Visual indication that the desired feed tray is actuated.

6. A control circuit according to claim 4 further including electrically operable charge means connected to the gun and electrically connected to said control circuit for receiving energizing current therefrom to place the gun in a charge condition.

7. A control circuit according to claim 4 further including an ammunition position sensing switch mounted on 12 the gun to be actuated by a round of ammunition to indicate the presence of the round in the gun.

8. A control circuit for controlling the firing rate of an automatically operating gun comprising:

an electrical power source;

solenoid means cooperable With the gun for causing firing of the gun when said solenoid means is in an energized state;

switch means connected between said power source and said solenoid means for applying power to said solenoid means;

circuit means connected to said switch means for actuating said switch means in response to a preselected firing rate;

an AND gate circuit connected to said circuit means;

an oscillator circuit;

a rate selector switch having a plurality of terminals, certain ones of said terminals being connected to said oscillator circuit for setting the oscillatory rate of said oscillator circuit, said oscillatory rate corresponding to said preselected firing rate;

a trigger circuit connected to said AND gate for applying a fire signal thereto, and connected to said selector switch to apply an operating voltage to said oscillator circuit when said selector switch is contacting one of said certain plurality of terminals;

a one-shot multivibrator having an input connected to said oscillator circuit for receiving pulse signal information from said oscillator circuit, and having an output connected to said AND gate for delivering thereto square wave pulses of fixed duration but at a rate corresponding to said oscillatory rate, whereby, the presence of both the first signal and square wave pulses at said AND gate will cause said switch means to be actuated alternately on and oil? in response to the rate of said square wave pulses to correspondingly fire the gun at the same rate.

9. A control circuit for controlling the firing of a gun according to claim 8 further including a pulse forming network having an input connected to one of the terminals of said selector switch for receiving said fire signal from said trigger circuit when said selector switch is positioned to deactuate said oscillator circuit and to actuate said pulse forming network; an OR gate having one input connected to the output of said pulse forming network and another network connected to the output of said oscillator circuit, said OR gate having output connected to the input of said multivibrator, whereby when said selector switch is positioned to activate said oscillator circuit, said pulse network is deactivated, thereby allowing the pulses of said oscillator circuit to pass through said OR gate, and when said selector switch is positioned to deactivate said oscillator circuit and activate said pulse network, a singular pulse is applied to said OR gate thereby allowing the gun to be operated in a semi-automatic mode.

10. Control apparatus for a gun having a firing solenoid, an ammunition feed tray which is movable between a working position and a neutral position rounds of ammunition in said feed tray, an ammunition position actuator, and a charger and drive actuator comprising:

first circuit means connected to said drive actuator for selectively charging the gun;

second circuit means connected to said ammunition posi tion actuator to place a round of ammunition in the gun for firing;

third circuit means connected to said firing solenoid for energizing said solenoid to fire the gun;

fourth circuit means interconnected between said first and second circuit means for preventing charging of the gun when a round of ammunition is in position in the gun;

means for moving said ammunition feed tray between said working and neutral positions; and

fifth circuit means interconnected between said moving 13 means and said first, second and fourth circuit means to prevent charging of said gun when said feed tray is in its working position, said fifth circuit means including means to operate said moving means to position said feed tray in its neutral position permitting char ging of the gun.

References Cited UNITED STATES PATENTS 2,368,307 1/1945 Koonz et a1. 89135 2,413,241 12/1946 Mejean et a1 89-1 14 Golden 89-135 X Taslitt 89129 X Marquardt 89135 Evans et a1 89135 X Greene.

Seidler 307-247 X BENJAMIN A. BORCHELT, Primary Examiner.

STEPHEN C. BENTLEY, Assistant Examiner.

US. Cl. X.R.

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