Firearm gas piston with power cavity and inertia valve

June 13, 1961

S. K. JANSON firearm gas piston with power cavity and

2,987,968

INERTIA VALVE

Filed Sept. 28, 1959

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FIG - 2

INVENTOR.

STEFAN K. JANSON BY-r^ z? _ .

United States Patent Office

2,987,968

Patented June 13, 1961

2,987,968

FIREARM GAS PISTON WITH POWER CAVITY AND INERTIA VALVE

Stefan K. Janson, New Haven, Conn., assignor to Olin

Mathieson Chemical Corporation, a corporation of ⁸Virginia

Filed Sept. 28,1959, Ser. No. 842,907

Claim. (Cl. 89—193)

The present invention relates to gas operated firearms and in particular deals with a gas control device associated with such firearms.

In firearms of the gas operated type in which propellant gases are tapped from the barrel and employed to drive a piston which actuates the gun action, it is often desirable to have some means of regulating the gas energy transmitted to the piston. This is especially desirable in firearms which are adapted to fire a variety of types of ammunition, each developing widely varying pressure characteristics in the barrel. Obviously, if no control device is provided to compensate for the varying pressures, the gun must be designed to function with that round of ammunition which develops the least gas pressure energy on the operating piston. However, when firing rounds which develop high pressure levels, excessive energy is transmitted to the action which tends to increase wear and tear and shortens the life of the firearm. To avoid this occurrence it is desirable to control the gas energy transmitted to the operating piston in such manner that, essentially, a constant amount of energy is transmitted independent of the type of round being fired.

In a co-pending application, S.N. 796,087, filed December 2, 1959 by Rolf H. Wild, there is disclosed a control device which is sensitive to pressure and time and which bleeds excessive gases to the atmosphere as soon as a certain value of energy , or impulse has been transmitted to the piston.

The present invention provides a different means for accomplishing a similar purpose by providing an inertia sensitive valve member which controls the admission of gases from the barrel to the gas cylinder. This inertia member is conditioned by the recoil of the gun prior to the occurrence of gas flow from the barrel to the cylinder. Depending upon the power of the recoil the valve is operative to preset the proper restriction or throttling effect in the gas conduit leading from the barrel to the cylinder before gas begins to flow.

The recoil movement of a shoulder firearm is dependent jointly upon the round being fired, upon the weight of the firearm and upon the resistance provided by the shooter. For practical purposes the resistance of the shooter does not significantly affect the initial gun recoil movement, at least up to the instant of gas flow from barrel to the cylinder. The time interval of the initial recoil and succeeding gas flow is of the order of 1 to 2 milliseconds and results in a comparatively small displacement of the overall gun. Consequently, the variation in resistance provided by various shooters is negligible in comparison with the recoil forces developed by the gas at this early time.

This initial increment of recoil movement can be employed to sense differences in ammunittion power and to condition a gas control device which includes a freely movable member. Thus, different values of initial recoil operate upon the movable member to establish a corresponding number of different relative positrons, each position presenting the desired cross-sectional area for gas flow through the valve most suitable for the round fired.

A further feature of the invention is the provision of a relatively small, compact valve device operative to insure that the power supplied to the action is substantially uniform in spite of variations in power of propellant charges.

A further feature of the invention is the provision of a double acting valve control device for a firearm.

A control device embracing certain features of the invention may comprise a firearms barrel, an adjacent gas cylinder including a working piston, said piston having a first bore defining a piston wall and a power cavity, the opposite end of said piston having a second bore for receiving a valve stem, conduit means defining a path for the transfer of gas leading from the barrel through the cylinder, the piston wall and thence into the power cavity, said valve stem being movable from a static position to a first positron corresponding to a light load recoil position wherein said conduit means is partially throttled, said valve stem being movable to a second position corresponding to a heavy load recoil position wherein said conduit means is further throttled, said piston being movable in response to the energy introduced by gas passing from the barrel to the power cavity effective to operate the action of the firearm, said piston being further operative to close said conduit means during the course of its working stroke whereby said transfer of gas is cut off.

Other features and advantages of the present invention will become more apparent from the succeeding specification when read in conjunction with the appended drawings in which:

FIG. 1 is a vertical section of a portion of a gas operated firearm with which the principles of the present invention may be associated and showing the valve stem in the static position.

FIG. 2 is a view similar to the illustration of FIG. 1 showing the working piston having moved through sufficient length of its working stroke, to cut off or close the conduit.

Referring now.in detail to the drawings there is shown a firearms barrel 10 connected to a gas cylinder 11 by means of a bracket 15 and enclosed by a threaded cap 12.

The cylinder 11 carries a working piston 13 formed with a first bore 14 defining a power cavity. The bore 14 communicates with a second bore 16 carrying a valve stem 17.

The valve stem is shown in the static position (FIG. 1) relative to the working piston 14 and is so held by a light coil spring 18, one end of which contacts a washer 19 while the opposite end of the spring engages the working piston as at 20.

The valve stem 17 is operative by virtue of its inertia and the motion incident to recoil upon firing to move to the dotted line positions indicated by the letters A—B (FIG. 1) in a manner which will be described in greater detail hreinafter.

In conventional fashion, the working piston 13 is operative to drive the action of the firearm by means of slide arm 21 engaging the piston by means of a pin 22 in well known fashion. A slot 23 formed in the cylinder provides clearance for the stroke of the pin while coil spring 24 operates as a return spring urging the piston 13 to the right to the static position shown in FIG. 1.

As stated previously, the recoil developed upon firing varies from load to load and the violence of recoil and corresponding displacement of the overall firearm upon firing a magnum load is much sharper than the recoil and displacement developed from a light load. It is desirable to introduce a fairly uniform amount of power into the means operating the gun action and to this end the present invention provides a novel device for sensing the differences in recoil effect from light loads to heavy loads.

The motion of the overall gun during recoil in coop2,987,968 ³eration with the inertia of the valve stem 17 is effective to preset the valve stem relative to a conduit 25 leading from the barrel 10 through the bracket 15, the cylinder 11, the bore 16 into the power cavity to throttle the conduit selectively.

The control device operates in the following fashion:

Assume that a light load were fired in the firearm with a corresponding light recoil. The inertia of the valve stem 17, in combination with the recoil of the main body of the weapon would result in a change in the relative position.

In the A position, the passage of gas from the barrel 10 to the power cavity 14 is slightly throttled; however, a sufficient opening remains in the conduit 25 to insure the transmittal of sufficient energy to drive the piston 13 through its full working stroke.

In contrast, a heavy or magnum load develops a correspondingly heavier recoil with the result that the valve stem 17 moves to the relative position designated by the dotted line labelled B.

In this position the conduit 25 is throttled further to prevent the transmittal of an excessive amount of energy to the piston 13. Obviously, loads representing power levels falling between light loads and heavy loads are effective to position the stem 17 at points intermediate the A and B positions.

Referring now to FIG. 2, there is shown a representation of the working piston in the course of traversing its working stroke. Note that the valve stem 17 has begun to return to its static position in response to the pressure within the power cavity 14. More significantly, note that the piston, per se, has effectively operated as a second valve in closing off the conduit 25 operative to provide an additional control upon the gas admitted to the power cavity.

Thus, the control device of the present invention provides a primary valve means, namely, the cooperation between the valve stem 17 and the piston and a secondary valve means, namely the cooperation between the piston 13 and the cylinder 11 for regulating or controlling the admission and discharge of gas to and from the power cavity 14.

Stated otherwise, the invention effects a dual control upon the gas flow to and from the power cavity wherein 5 the stem 17 is operative to throttle the conduit 25 while the piston 13 is operative to close the conduit completely.

While the present disclosure illustrates a single embodiment of the invention, it is anticipated that a wide variety of modifications and design changes may be de10 vised without departing from the spirit and scope thereof.