Device For Controlling The Firing Frequency In Automatic Firearms

Abstract

A device for changing the firing frequency of rapidly firing automatic firearms in which a buffer case attached to the housing of the firearm contains a buffer spring urging the head of the buffer case into the housing of the reciprocating breech block. A hydraulic cylinder is surrounded by a recoil spring and the latter is disposed within the buffer spring and has a cylinder head arranged within the buffer head. A number of radially slidable locking pins in the cylinder head is adapted to be locked to an axial locking bolt on the breech block when the latter moves in one direction in which the two mentioned springs are put under higher tension while the buffer head and cylinder are moved with the breech block in the same direction. The piston and piston rod are stationary and the pressure fluid in the hydraulic cylinder is displaced by the moving cylinder through bores in the piston from one side to the other side thereof until an axially slidable seal closes the bores in the piston. The pressure fluid can now return the one side of the piston only through radial throttling bores in the piston rod which has an axial bore extending through the center of the piston and this causes a delay in the return of the breech block in the other direction. Preferably, an axially adjustable needle valve in the piston rod controls the discharge ends of the radial bores into the axial bore of the piston rod and permits a predetermined continuous change in the firing frequency of the firearm down to a very low number of shots per minute.

Description

The present invention relates to an automatic firearm, as for instance, a rapid-fire cannon or a machine gun, with rapid firing frequency (cadence), in which if necessary the firing frequency can be continuously varied. The firing frequency may be throttled to such an extent that practically a single shot may be fired.

In rapid-fire cannons the firing frequency is customarily in the order of size of approximately 1000 shots per minute. In accordance with the invention, the firing frequency may be decreased to a value of only approximately 60 shots per minute.

Referring to the prior art, it is desired to point out that in the German laid open specification No. 1,428,774 (Howa Kogyo K. K., Nagoya/Japan) of May 14, 1964 --Priority Japan: June 28, 1963--a device has already been disclosed for the lowering of the firing speed in automatic firearms. By "Feuerwaffe" (firearms), in the sense of the mentioned German laid open specification, in contrast to the present invention is to be understood, however, a conventional fully automatic rifle, namely an infantry weapon with a firing frequency of approximately 700 to 800 shots per minute. According to the disclosure in this German laid open specification this high firing frequency may be lowered to approximately 400 to 500 shots per minute, in order thereby to attain a higher firing accuracy.

In the device according to the German laid open specification, the desired object is attained by arranging in the weapon an auxiliary mechanism actuatable by means of the trigger, which holds back temporarily the firing pin by a locked breech.

In automatic weapons, for example rapid-fire cannons or machine guns, such an auxiliary mechanism operable by the trigger is useless and for reasons of safety prohibitive, because for example with hot shot weapon a cartridge remaining in the cartridge chamber could lead to an automatic ignition. It is obvious that in such a case not only the weapon is destroyed, but above all the life of the marksman operating the weapon would be endangered to the most serious extent.

With the device according to the invention, among others, the combat-technical problem is solved, establishing a sustained fire at predetermined, desired or intended time intervals, respectively, with the greatest possible accuracy in firing. A further important object of the invention is to employ the device in a more economical-logistic range to effect, in a matter not calculable in advance, a saving in munitions.

A rapid firing firearm provided with a device in accordance with the invention and comprising means for continuously changing the firing frequency from a high value to a very low value will now be described with reference to the accompany drawings:

IN THE DRAWINGS

FIG. 1 illustrates a vertical section of the device according to the invention before its connection with the rapidly returning breech-block of the weapon, and

FIG. 2 illustrates the same vertical section as FIG. 1, however, after the connection of the device according to the invention, with the rapid returning breech-block has taken place.

Referring to the drawings, the rear part of a weapon housing 1 has threadedly attached thereto a buffer case 1a in which are disposed mechanically and hydraulically operating means, which cause a rapid reverse movement of the breech-block mass. For the alteration of the firing frequency, such as a decrease in the firing frequency, the following arrangement is provided:

In front of the hollow cylindrical buffer case 1a is arranged, so as to extend into the housing 1, a buffer head 2 whose end wall 2a is provided with a central aperture 2c. Into the hollow cylindrical rear portion of the buffer head 2 extends axially slidably the head 6 of a cylinder 5 adapted to contain a displaceable fluid pressure medium. The cylinder 5 has mounted therein a piston 4 having a tubular piston rod 4d whose outermost or right-hand end projecting from the right-hand end of the cylinder 5 is fixedly attached to the end wall 1b of the buffer case 1a. A helical recoil spring 8 surrounds the cylinder 5 and engages with one end a shoulder on the piston head 6 and with its other end engages the end wall 1b of the buffer case 1a.

A helical buffer spring 3 surrounds with clearance the helical spring 3 and with one end engages the right-hand end of the buffer head 2 and with its other end the end wall of the buffer case 1a. The cylinder head 6 carries in each of four radial bores a slidable locking pin 7 adapted to engage an axial locking bolt 13 attached to the rear face of the breech-block 12.

After the shot has been fired, the front surface 13a of the locking bolt 13 strikes a surface 6a forming the bottom of a recess 6b in the cylinder head 6. With a slight temporary delay the breech-block 12 engages then with its end surface 12a correspondingly constructed front surface 2a on the buffer head 2. This causes both the buffer spring 3 as well as the recoil spring 8 to be tensioned until the kinetic energy of the breech-block mass is absorbed. Furthermore, when the front surface 13a of the bolt 13 strikes the surface 6a in the cylinder head 6 the hydraulic cylinder 5 is urged rearwardly toward the right by the head 6. The radially disposed locking pins 7 which are arranged uniformly distributed circumferentially in the head 6 ride positively along the guide surface 2b in the buffer head 2 and are moved in engagement with the inclined surface 13b on the rear face of the collar 13c of the bolt 13. This results in a locking engagement between the surface 13b and the locking pins 7.

The pressure fluid stored in the left-hand chamber 5a of the cylinder 5 is controlled by a plurality of axially extending bores 4a in the stationary piston 4 and causes a removal of a sealing member 11a of the sealing system 11 which is arranged on the tubular piston rod 4d from the right-hand side of the piston 4 in a direction to uncover or open these bores 4a. The pressure medium then flows through these bores 4a and enters the rear or right-hand end of the axially movable cylinder 5, namely the chamber 5b in which the piston rod 4d is disposed. The time expended in this operation is proportional to the complete absorption of the kinetic energy of the breech-block mass. The energy stored in the two helical springs 3 and 8 is now again released. The release of the energy takes place, however, not in sudden bursts, but in a delayed manner described in the following:

The pressure medium which has reached the chamber 5b, in view of the fact that the bores 4a are now closed by the sealing member 11a and the compression spring 11b acting on the same, can no longer flow through these bores 4a and back into the chamber 5a. The pressure medium, however, can take now a path over one (or several) radial throttle-passages 4b provided with the tubular piston rod 4d of the piston 4. These throttle passages 4b are connected with a reduced axial bore 4c in the piston rod 4d and extend through the center of the piston 4 so that the pressure medium may reach along this path, namely through the radial passages 4b and the axial bore 4c again the left-hand chamber 5a of the cylinder 5.

In view of this operation and particularly by a proper selection of the size of the throttle passages 4b, the firing frequency of the firearm is already substantially decreased. This decrease, however, would be a rather accidental or arbitrary one, because it is adjusted only for one predetermined firing frequency.

The invention is, however, not limited to a firing frequency adjustment selected accidentally and arbitrarily and limited in this described manner to one frequency.

With the assistance of additional means to be described in the following, the firing frequency can be continuously adjusted from a maximum to a minimum value.

To the buffer housing is fixed, as already mentioned, in the longitudinal axis of the weapon the right-hand end of the tubular piston rod 4d, namely by a threaded bolt and nut connection 9a. A nozzle needle 9 is inserted in the somewhat enlarged right-hand portion of the axial bore in the tubular piston rod 4d and is in threaded engagement with this axial bore at 9b. The left-hand conical end 9c of the nozzle needle 9 engages a conical valve seat at the place where the radial passages 4b communicate with the axial bore 4c so as to control these radial passages 4b. By axially adjusting the needle 9 in the axial bore of the tubular piston rod 9d, the quantity of the pressure medium passing from the radial passages 4b into the axial bore 4c may be changed continuously, so that the firing frequency is continuously changeable and may be selected according to the tactical combat requirements.

The axial adjustment of the nozzle needle 9 takes place in any desired manner, for example, by a screwdriver or the like.

Upon forward movement of the breech block 12 when rigidly locked with the buffer system, the radial locking pins 7 travel radially back into their starting position and thereby release at the same time their rigid locking with the locking bolt 13. The breech-block 12 with its axial locking bolt 13 is now, through the action of closure springs, not shown, returned into its starting position.

Claims

What we claim is:

1. A device for controlling the firing frequency of a rapidly firing automatic firearm having a housing and an axially reciprocable breech-block therein, said device comprising a buffer case fixedly attached to said housing and having a buffer spring therein acting upon an axially movable buffer head adapted to be engaged and tensioned by said breech-block when the latter is moved in one direction, an axially movable hydraulic cylinder engaged by a recoil spring in said buffer case, said cylinder having a head with movable locking pins therein for lockingly engaging said breech-block when the same has been moved in said one direction and has engaged said buffer head, a piston in said hydraulic cylinder and fixedly attached to said buffer case, passages in said piston for permitting hydraulic fluid to pass therethrough when said cylinder is moved by said breech-block in said one direction, sealing means for closing said passages at the end of said movement of said breech-block, and throttling apertures in said piston for returning the hydraulic fluid to the other side of said piston and thereby delaying the movement of said breech-block, buffer head and cylinder in the other direction.

2. A device for controlling the firing frequency of a rapidly firing automatic firearm having a housing and an axially reciprocable breech-block in said housing, wherein the improvement comprises a buffer case attached to said housing and having a buffer head at one end extending into said housing, an axially movable cylinder containing a fluid pressure medium in said buffer case, a stationary piston in said cylinder, said piston having an axially bored piston rod fixedly attached to said buffer case, a buffer spring between said buffer head and an opposite closed end of said buffer case, a head on said cylinder and having therein a central cavity and a number of radial slidable locking pins adapted to move into said cavity, a recoil spring surrounding said cylinder and extending between said head and the closed end of said buffer case, fluid passages in said piston for connecting the two chambers to both sides of said piston in said cylinder with each other, a spring operated sealing member on said piston rod adapted to close said fluid passages, an axially extending bolt on said breech-block for entering upon movement of said breech-block in one direction in said central cavity of said cylinder head to be locked thereto by said radial pins in said cylinder head and for compressing said spring and for moving said cylinder whereby the fluid pressure medium is displaced through passages in said piston from one chamber to the other chamber in said cylinder until said sealing member closes said passages, said axially bored piston rod having radial throttling passages for returning with delay the displaced fluid pressure medium from said other chamber to said one chamber from which it was displaced by means of the axial bore in said piston rod, and then permitting after a delay a release of said locking pins from said axially extending bolt during the movement of said breech-block in the other direction.

3. A device according to claim 2, including means for continuously changing the throttling effect of said throttling passages, said means comprising a valve seat in said axial bore of said piston rod into which the radial throttling passages terminate, and an adjustable needle valve axially movable in said axial bore for continuously controlling the discharge aperture of said radial passages.

4. A device according to claim 2, including means for continuously changing the throttling effect of said throttling passages, said means comprising a valve seat in said axial bore of said piston rod into which the radial throttling passages terminate, and an adjustable needle valve axially movable in said axial bore for continuously controlling the discharge aperture of said radial passages, said needle valve extending through said axial bore toward the end of the piston rod which is fixedly connected to said buffer case, said end of said piston rod having a threaded connection with said needle valve which is accessible from the exterior of said buffer case for rotatable adjustment.