Additional safety device for sear mechanism for firearms

A sear mechanism for firearms comprises a sear box 12, and an additional safety device to prevent the hammer 16 from releasing accidentally and to fire under the action of inertial forces acting along the direction of the axis of the barrel in case of impact of the firearm, the additional safety device being an interposing element 60 which is slidably mounted below the firing pin latch 43 in a housing having a first inclined plane element 63 and a second inclined plane element 63a which are arranged between lateral walls 62 to form a seat 61 which holds element 60 in a first position where it does not interfere with the operation of the firing pin latch 43 but allows said element 60 to move into a position where it prevents the pin latch 43 from moving downwardly to disengage hammer 16.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention refers to a new additional safety device for a sear mechanism for firearms.

(2) Description of Related Art

In general, the field of portable, semi-automatic or automatic firearms foresees different solutions for the sear mechanism, which comprises a mobile element which holds the hammer in the cocking position.

Following the voluntary pulling of the trigger, the mobile element frees the hammer and allows it to hit against a firing pin under the thrust of a preloaded elastic element.

Such a mobile element can be realized, for example as a sear or as a sear pawl, pivoted at a fixed part of the body of the firearm and biased by an elastic element. To carry out its function such a mobile element is thus engaged with both the trigger and with the hammer.

Such a mobile sear element constitutes a delicate detail of the sear mechanism, since it is stressed mechanically and has a complex form, and it is thus generally made from metal.

Since the hammer and the sear element are equipped with additional engagement teeth, due to problems of wear of the interfacing contact surfaces, the hammer must also necessarily be made from metal.

A purpose of the present invention to provide an improved sear mechanism for firearms. U.S. patent application Ser. No. 10/390,939, which is incorporated herein by reference describes a sear mechanism which is adaptable for use in the present invention.

Hereafter specific reference shall be made to a rifle, even though that which is object of the invention can be applied to all firearms, including side-by-side, semi-automatic, rifled and military firearms, etc.

Moreover, given that the invention is intended for experts in the field of firearms, it the detailed description of the structure and operation of a firearm, in particular of a rifle like the one described is omitted. This description is set forth to point out the functions of the parts of a firearm which are the subject matter of the technical problem which is the basis of the invention.

BRIEF SUMMARY OF THE INVENTION

The invention provides a sear mechanism for firearms comprising a sear box12, a trigger15mounted in said sear box12on a rotation pin18which is acted upon by an elastic return element25, and having a hammer16mounted in said sear box12on a pin of the hammer31and upon which acts an elastic thrust element33, said hammer16being equipped with a mounting tooth40for engaging sear tooth41, and a breechblock carrier13carrying a firing pin14, and comprising a sear device17controlled by said trigger15which said hammer16, motion between a cocking position A in engagement with said sear tooth41and a striking position B against said firing pin14, wherein said sear tooth41is fixed and integral with said sear box12, said hammer pin31, is in engagement with a slot32of said sear box12said sear device17comprises at one end an engagement element43mounted on said hammer pin31said pin being adapted to cause said hammer pin to advance in said slot32, said motion between said cocking position A and said striking position B of said hammer16comprising an initial translation step and a subsequent rotary step under the action of said elastic thrust element33, said sear device17being connected at an opposite end thereof to said trigger15, and including an additional safety device which comprises an interposing element60which is slidably mounted below the firing pin latch43in a housing having a first inclined plane element63and a second inclined plane element63A which are arranged between lateral walls62to form a seat61which holds element60in a first position where it does not interfere with the operation of the firing pin latch43but allows said element60to move into a position where it prevents the pin latch43from moving downwardly to disengage hammer16.

The additional passive safety device prevents the hammer16from being accidentally released by the disengagement of sear tooth41from mounting tooth40by an impact force or unforeseen vibration. The passive safety device comprises an interposing element60which is slidably mounted below the firing pin latch43in a housing having a first inclined plane element63and a second inclined plane element63A which are arranged between lateral walls62to form a seat61which holds element60in a first position where it does not interfere with the operation of the firing pin latch43but allows said element60to move into either a forward position (FIG. 3A) or rearward position (FIG. 4A) where it prevents the pin latch43from moving downwardly to disengage hammer16.

The additional passive safety device prevents the hammer from releasing accidentally and firing under the action of inertial forces acting along the direction of the longitudinal axis of the barrel due to sudden acceleration. Thus, if the firearm is dropped and either end strikes an object, the interposing element60will move along one of the inclined plane elements along the longitudinal axis of the firearm to prevent the firing pin latch43from becoming disengaging the hammer16.

Accordingly, it is a primary object of the present invention to provide an additional passive safety device that is automatically activated under impact conditions that may cause the firing pin latch to disengage but is not activated during the normal handling and firing of the firearm.

Another object of the present invention is to provide a sear mechanism which is lighter and may be made of elements which comprise a plastic material.

Another object of the invention is to permit the use of a low actuation force to activate the trigger and provide a structure which is not subject to excessive wear.

It is also an object of the invention to provide a safer design which is simple to assemble and provides greater cost-effectiveness in manufacturing.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIG. 1, the sear mechanism10for firearms comprises a sear box12, which can be inserted in the structure of a firearm, for example in the stock or fore-end.

The firearm comprises a well known breechblock carrier13carrying a firing pin14, as partially shown inFIGS. 3–6.

On the sear box12are mounted a trigger15, a hammer16and a sear device17which when controlled by trigger15, releases the hammer16from a cocking position A in engagement on sear box12and a striking position B against the firing pin14. As shown inFIGS. 1–6, the trigger15is mounted at the sear box12through a rotation pin18, housed in a hole19, so as to be protruding below the front part of the sear box12.

The trigger15consists of an upper forked portion20mounted straddling an abutment rib21of the sear box12. A connection pin24, to which the sear device17is hinged, is applied to the upper forked portion20of the trigger. In the sear mechanism10, described only as an example, the sear device17is hinged in offset position and forward with respect to the rotation pin18.

In the cocking position A and in the striking position B of the hammer, the pin24is respectively in abutment with an upper surface portion22or a lower surface portion23of the rib21.

An elastic return element25acts on the trigger15. This elastic return element may be a spring, which takes the trigger15back to rest position when it is released after firing.

In the proposed embodiment, the return spring25also ensures the return into rest position of the sear device17hinged to the trigger15.

The return spring25is made up of a first end27, arranged in abutment on a breechblock locking lever26, of a first winding28, arranged around the rotation pin18of the trigger, of a second winding29, arranged around the connection pin24between the sear device17and the trigger15and of a second end30, arranged in abutment on the sear device17.

The hammer16is mounted at a rear portion of the sear box12through a pin of the hammer31, housed in a slot32arranged in such a sear box12.

An elastic thrusting element33acts on hammer16, which, in the example shown, consists of a spring made up of two windings34, which are symmetrical with respect to a middle plane35of the sear box12and are arranged on housing sleeves36of the hammer pin31, which protrude from the side of the hammer16.

The preloaded thrust spring33is equipped with two ends37, bound to the sear box12, and with a bridge portion38between the windings34, positioned in abutment on a mobile lower face39of the hammer16.

In the cocking position A, the hammer16is held by a fixed sear tooth41, realised integral with the sear box12and matching a mounting tooth40arranged on a rear wall of the hammer16.

Since the sear tooth41is fixed, it is possible to make it from plastic, thus allowing plastic to also be used for the hammer. The mass of the sear mechanism is thus substantially reduced whilst still ensuring low wear conditions between the interfacing contact surfaces.

The sear device17of the mechanism for firearms10is hinged at one of its front ends to the trigger15and is equipped at the opposite end with an element for engagement with the pin of the hammer31.

As shown inFIGS. 1 to 6, the sear device17consists of a first translating connection lever42and a second rototranslating firing pin latch43, coupled together through matching engagement means.

The connection lever42, which has a variously shaped profile, has a perforated front end44and is hinged to the connection pin24in a lateral position with respect to the trigger15. In a central portion45the connection lever42extends next to the inner wall of the sear box12and in the rear part has an arm46, arranged in the middle plane35of the sear box12and extending downwards, carrying a U-shaped engagement element47.

The firing pin latch43, also operating in the middle plane35and fitted onto the pin of the hammer31, constitutes the engagement element with the pin of the hammer suitable for causing it to advance in the slot32. For such purpose the hammer16is equipped with a groove48in the middle plane to avoid movement interference.

The firing pin latch43consists of three tailpieces which extend downwards, upwards and backwards.

A tapered lower tailpiece49constitutes the engagement element matching the U-shaped engagement element47of the connection lever42.

An upper intervention tailpiece50, extending diagonally towards the front part of the sear box12, frees the firing pin14inside the breechblock13when it is pressed against a latch51of the firing pin14. Finally, the firing pin latch43is equipped with a rear tailpiece52, carrying a safety catch53in engagement in an opening54of the rear wall of the sear box12.

The sear mechanism10has an initial cocking position A (FIG. 3), in which the trigger15is in rest position and the hammer16is held by the fixed sear tooth41, following the voluntary pulling of the trigger15in the direction of the arrow F, the trigger rotates with a pivot in its rotation pin18, causing the advance through translation of the first connection lever42. The connection lever42gives the firing pin latch43motion which is initially rotational and then translational.

Indeed, since the matching engagement means between the connection lever42and the firing pin latch43offset at the bottom with respect to the pin of the hammer31, the firing pin latch43is initially made to rotate about the pin of the hammer31.

The upper intervention tailpiece then goes into abutment against the latch51of the firing pin14and presses it releasing the motion of the firing pin14in the breechblock13.

When the sear mechanism10is in an unlocking position of the firing pin C, shown inFIG. 5, the further rotary motion of the firing pin latch43is prevented. The connection lever42then pulls the firing pin latch43into translational advancing motion which also involves the hammer16, the pin31of which advances in the slot32, which allows for translational movement of pin31.

The mounting tooth of the hammer40is then released from the fixed sear tooth41and, thrusted by the preloaded spring33, goes into the striking position B (FIG. 6).

The motion of the hammer16between the cocking position A and the striking position B is therefore made up of an initial translation step and a subsequent rotary step under the action of said elastic thrust spring33.

The trigger15, released, returns into the starting position through the effect of the return spring25, which also resets the initial position of the sear device17.

The sear mechanism10, according to the proposed embodiment, when it is in cocking position A, is equipped with a safety device which prevents the firing of an accidental shot following hard knocks, such as those generated by the use of the firearm to knock down an obstacle, or in the case of the firearm itself being falling to the ground.

Indeed, the translational movement of the pin of the hammer31and of the hammer16itself to free the mounting tooth40from the fixed sear tooth41is prevented by the safety catch53of the firing pin latch43, which is in engagement in the opening54of the sear box12.

Only by pulling the trigger15is it possible to cause the rotation of the rear tailpiece52carrying the safety catch53, which releases it from the opening54of the sear box12, allowing the subsequent translational movement of the firing pin latch43and thus of the hammer16.

The sear mechanism for firearms which is subject of the present invention has the advantage of making possible the elimination of the sear connecting lever to hold the hammer in cocking position.

The fact that the hooking of the mounting tooth of the hammer to a fixed tooth of the sear box has been foreseen advantageously allows the hammer to be made from plastic, making the structure substantially lighter. Indeed, due to problems of wear of the interfacing contact surfaces, the hammer can be made from plastic only if the sear tooth is also made from plastic.

Moreover, the sear mechanism, object of the present invention, has a simplified structure, consisting of a low number of components, which advantageously allows a great cost-effectiveness of construction and simplicity of assembly to be obtained.

The firearm comprises a breechblock carrier13carrying a firing pin14, only partially represented inFIGS. 3 to 6and already known.

On the sear box12are mounted a trigger15, a hammer16and a sear device17which, when controlled by the trigger15, gives the hammer16motion between a cocking position A in engagement on the sear box12and a striking position B against the firing pin14.

The additional safety device of the invention provides a passive safety device that is activated by sudden acceleration or sudden impact loads on the firearm without any intervention of the user of the firearm.

When the firearm is subjected to sudden acceleration which results in an impact such as is caused by the dropping of a firearm on a hard surface, inertial forces may be generated which may cause the moveable parts to move and cause the disengagement of the firing pin latch43from the opening54of the sear box12. The hammer16, being held in place in this condition only by the elastic return element25, may be released and strike the firing pin which can cause an accidental firing.

As shown inFIGS. 1 to 6, the additional safety device of the sear mechanism, comprises an interposing element60housed in a seat61of the sear box12under the rear tailpiece52of the safety catch53. In a preferred embodiment, for example shown inFIG. 1and in the enlarged detail ofFIG. 2the interposing element60is a sphere and the seat61comprises lateral containment walls62and62A which are arranged parallel to each other along the longitudinal axis of the firearm. The distance between the lateral walls62and62A is slightly greater than the sphere's diameter. The inclined plane elements63and63A are arranged between the lateral walls62facing each other and are inclined to converge towards one another at the bottom of the seat61. The inclined plane elements63and63A are spaced by a distance less than the sphere's diameter to form a seat61which is a constriction between the inclined plane elements63and63A having an open bottom as shown inFIG. 4A.FIG. 3Ashows sphere60in a forward position which sphere60would assume if translational movement were induced by sudden acceleration caused by dropping the firearm on its muzzle (not shown).FIG. 4Ashows sphere60in a rearward position which sphere60would assume if translational movement were induced by sudden acceleration caused by dropping the firearm on its butt end (not shown).FIG. 5Ashows sphere60in a neutral position which sphere60would assume when the firearm was held in a substantially level position (not shown).FIG. 6Ashows sphere60in a neutral position which sphere60would assume when the firearm has just been fired as shown by the hammer16in contact with firing pin14.

The sphere60moves in response to sudden high impact forces (inertial forces) which also act on safety catch53. The inertial force causes sphere60to move along the inclined plane elements63,63A into position under the rear tailpiece52of the safety catch53to prevent the safety catch53from moving downwardly under the influence of inertial forces. After the termination of the application of an inertial force, caused by sudden acceleration, only gravity acts on the sphere60which is free to move according to the orientation of the firearm. For example, the gravitational forces applied to sphere60by moving the firearm, e.g. from the horizontal position to a non-horizontal position cause the sphere60to move out of the neutral position under the tailpiece52. During normal firing, when the trigger activates the firing mechanism, the safety catch53is rotated and the rear tailpiece52shifts the sphere60downwardly towards the bottom of the seat61, i.e. in the neutral position where it does not interfere with the firing operation where it does not interfere with the firing operation.

FIG. 5Ashows the terminal edges65and65A of inclined plane63and63A as having a substantially flat profile that provides support points66and66A as shown inFIG. 4Athat provide a stop for sphere60.

When inertial forces are directed either towards the front or towards the rear part of the firearm, the sphere slides or translates respectively over the front inclined plane element63or rear inclined plane element63A (FIGS. 3 and 4) interposing itself between the rear tailpiece52of the safety catch53and the sear box12. Any downward movement of the firing pin latch43which could cause release of the hammer16is therefore prevented.

When the firearm is handled for firing, the sphere60is housed in an opening64on seat61(FIGS. 5 and 6) and does not interfere with the downward movement of the firing pin latch43. Seat61is formed by the spaced opening defined by inclined planes63and63A.

While the preferred embodiment of the interposing element60is a sphere or ball of a material which may be metal or plastic, it is possible to use other spherically shaped elements which can exhibit translational or rotational movement in response to sudden acceleration caused by impact loading. These spherically shaped elements may comprise rounded objects of varying geometries that can be slidably mounted in opening64on the bottom of seat61. Further, cylinders or rollers as well as sliding wedges may be provided as interposing elements.