Abstract:
An improved compressed gas operated pistol is provided which maximizes use of compressed gas energy by minimizing loss of energy from the chamber into the magazine. An aft end portion of the barrel of the pistol is formed extended as a thin wall portion. When the trigger of the pistol is actuated, this thin wall portion of the barrel is fitted tightly into the chamber, confining the next pellet to be fired within the cylindrical walls of the thin wall portion and the rear surface of the chamber, and sealing off the chamber from the magazine. In this manner, the full impact of the energy provided for firing by the compressed gas cylinder to the chamber is imparted on the pellet.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention concerns a compressed gas operated pistol, and, more specifically, a compressed gas operated pistol that comprises a sealing element to isolate the chamber with respect to the opening of the ammunition magazine at the time of firing. 
   2. Background of the Related Art 
   Conventional art compressed gas operated pistols essentially comprise a support casing that defines a barrel zone, a trigger zone and a stock zone. The barrel zone contains a barrel with the rear end facing a chamber. In the trigger zone, there is a trigger connected to a hammer operating mechanism. In the stock zone, there is an ammunition magazine arranged to insert a pellet into said chamber through an opening prior to each shot. A pressurised gas cylinder with a valve chamber which, in turn, is connected to said chamber via a valve element pushed by an elastic means towards a closed position. Said valve element can be instantly moved to an open position by impact from said hammer. 
   One inconvenience presented by these conventional art pistols is that the magazine has said opening, through which the pellets enter the chamber, formed by an opening in an interior chamber wall, and this causes part of the pressurised gas supplied by the valve element to escape at the moment of firing, through said opening towards the interior of the magazine and which is not employed in impulsion for the pellet. In other words, there is a loss of the energy supplied by the gas pressure leading to a reduction in pellet range. 
   SUMMARY OF THE INVENTION 
   The objective of this invention is to provide a compressed gas operated pistol that comprises a sealing element operated by the trigger to isolate the chamber with respect to the ammunition magazine opening at the time of firing. 
   This objective is reached, in accordance with this invention, by providing a compressed gas operated pistol of the type described above, in which said barrel is able to move and is guided linearly to cause a movement of a rocker in an axial direction. This moving barrel is linked to said trigger and an elastic element is arranged to push the trigger and barrel assembly forwards to an inactive position. Said link between the trigger and barrel is such that, when the trigger is pressed against the force of said elastic element, the trigger moves the barrel backwards, thus operating a sealing element arranged so that it isolates the chamber with respect to the ammunition magazine. Preferably, said sealing element comprises a thin cylindrical wall directly arranged in said rear end of the barrel, defining an interior surface that is a continuation of the barrel bore surface, an exterior surface that can be adjusted inside the interior surface of the chamber, and a final perimeter edge. This thin cylindrical wall is arranged in such a manner that, when the barrel is moved backwards by the trigger, the thin cylindrical wall fits tightly into the chamber, collecting on its passage along the path said pellet, which is located in the chamber, until said final perimeter edge is supported against the rear surface of the chamber, thus sealing the entrance for the compressed gas. In this position, the thin cylindrical wall arranged in the rear end of the barrel takes over the functions of the chamber and, at the same time, the exterior surface of the thin cylindrical wall closes off the magazine opening to guarantee that the gas released during firing passes into the barrel bore and all its energy is fully employed in driving the pellet forward. 
   As is usual, the ammunition magazine comprises an ammunition store forming a column of several pellets. This store communicates with the chamber through said opening and a spring-loaded ammunition push mechanism is arranged to push said column of pellets towards the chamber, with the last (uppermost) pellet in the column remaining in the chamber. 
   In order to prevent the final perimeter edge of the thin cylindrical wall, upon penetrating the chamber, from trapping the penultimate pellet against the rear wall of the chamber, which would make firing impossible, this invention provides a means to prevent this, comprising a trap that is jointed with respect to a shaft and arranged in said opening between said ammunition store and the chamber. In the non-operational position, this trap is pushed upwards by the penultimate pellet in the column by virtue of the magazine spring force, and is set with one end arranged between said penultimate pellet and the last pellet, which is now located in the chamber. When the thin cylindrical wall of the rear end of the barrel enters the chamber, the final perimeter edge pushes said trap downwards, which drags along the penultimate pellet and with it, the rest of the column against the force of said magazine spring, leaving the last pellet free in the chamber so that it can be collected inside the thin cylindrical wall. For this reason, the trap has a suitable transverse section profile. As is usual, the outside diameter of the pellet is slightly less than the inside diameter of the barrel bore to ensure that the pellet does not fall out of the barrel muzzle and to prevent loss of pressure between the pellet and the barrel. 
   Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other characteristics and advantages are better understood from the following detailed description of a constructional example, with reference to the included drawings, in which: 
       FIG. 1  is a perspective view of the compressed gas operated pistol in accordance with this invention; 
       FIG. 2  is a longitudinal sectional view of the pistol shown in  FIG. 1 ; 
       FIG. 3  is an enlarged view of area III of  FIG. 2 , showing a part of the mechanism in a resting position; 
       FIG. 4  is an enlarged view of area III of  FIG. 2 , showing a part of the mechanism is a firing position; 
       FIG. 5  is a side view of a portion of the mechanism, in which the casing outline is shown by the dotted and broken lines; 
       FIGS. 6 and 7  are longitudinal sectional views of the sliding cover in resting and firing positions, respectively, and in which a casing outline is shown in dotted lines, and other mechanism outlines are shown in broken lines. 
       FIG. 8  is a transverse sectional view taken at line IX-IX of  FIG. 5 , and 
       FIG. 9  is a transverse sectional view of the case, which includes the magazine and gas cylinder removed from the stock zone. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   First referring to  FIGS. 1 and 2 , the compressed gas operated pistol of this invention comprises a support casing  26 , which defines a barrel zone  1 , a trigger zone  4 , and a stock zone  7 . In the barrel zone  1 , there is a barrel  2 , with rear end  2   a  facing a chamber  3 . In the trigger zone  4 , there is a trigger  5  connected to an operating mechanism for a hammer  6 . In the stock zone  7 , there is an ammunition magazine  8 , arranged to insert a pellet  9  in said chamber  3 , prior to each shot, and a pressurised gas cylinder  10  communicating with a valve chamber  11 . This valve chamber  11  is in turn, connected to said chamber  3  by means of a valve element  12 , which is pushed by elastic means (not shown) towards a closed position and which can be instantly moved to an open position by an impact from said hammer  6 . 
   As shown in  FIG. 2 , and in accordance with this invention, barrel  2  is able to move and is linearly guided in order to carry out a rocking movement in an axial direction. Barrel  2  is also linked to said trigger  5  by a catch  47 , which is firmly fixed to the barrel  2  and inserted into a cavity  46  in a trigger piece  5   a , of which trigger  5  forms an integral part. Said trigger piece  5   a  is installed in said trigger zone  4  so that it is able to slide guided linearly in a direction parallel to the barrel  2  axis, which is described in more detail with reference to  FIGS. 5 and 8 , and an elastic element  51 , such as an elastic traction spring, is arranged to push the trigger  5  and barrel  2  assembly forwards to a resting position. When trigger  5  is pressed against the force of spring  51 , cavity  46  drags the barrel  2  backwards, operating sealing elements  2   b ,  2   c  in order to isolate the chamber  3  with respect to the ammunition magazine  8 . 
   As shown in  FIGS. 3 and 4 , said sealing elements  2   b ,  2   c  comprise a thin cylindrical wall  2   b  that fits into said rear end  2   a  of barrel  2 , preferably by the machining of the actual material of barrel  2 . This thin cylindrical wall  2   b  defines an interior surface that is a continuation of the barrel bore surface, an exterior surface that can be adjusted to the interior surface of chamber  3 , and a final perimeter edge  2   c .  FIG. 3  shows the barrel  2  in the resting position, in which the sealing elements  2   b ,  2   c  of the rear end  2   a  of barrel  2  face the chamber  3 , which contains a pellet  9   a . The thin cylindrical wall  2   b  is arranged so that, when the barrel  2  is moved backwards by the trigger  5  (see  FIG. 4 ), the thin cylindrical wall  2   b  enters the chamber  3 , collecting along the way said pellet  9   a , which is located in the chamber  3 , until said final perimeter edge  2   c  is supported against the rear surface  24  of the chamber  3 , making sealed contact around the compressed gas entrance  25 , while said exterior surface isolates the chamber  3  from an opening  8   a  in the ammunition magazine  8 . 
   Typically, said ammunition magazine  8  comprises an ammunition store  19  for a column of pellets  9 , where this store  19  communicates with said chamber  3  through said opening  8   a . An ammunition push mechanism  20 , operated by spring  21 , is arranged to push said column of pellets  9  towards the chamber  3 . In accordance with this invention, a trap  22  jointed with respect to a shaft  23  is arranged in said opening  8   a  between said ammunition store  19  and the chamber  3 , so that it is pushed upwards by the penultimate pellet  9   b  in the column. In the resting position shown in  FIG. 3 , trap  22  is raised and with one end between the last and penultimate pellets,  9   a  and  9   b , respectively. Trap  22  has a transverse section profile that is suitable for retaining the pellet  9   a  in the chamber  3  and to act as a cam when it is pushed by the thin cylindrical wall  2   b  of the rear end  2   a  of barrel  2 . In the firing position shown in  FIG. 4 , the thin cylindrical wall  2   b , dragged by the trigger  5 , has penetrated inside the chamber  3  and the final perimeter edge  2   c  has pushed trap  22  downwards, which has dragged the penultimate pellet  9   b  and with it, the rest of the column of pellets  9  against the force of said spring  21  of the ammunition push mechanism  20 , thus freeing pellet  9   a , which has been inserted into the rear end  2   a  of the barrel  2 , which now acts as the chamber  3 , just as was described above. Valve element  12  has been moved under the impact of the hammer  6 , as will be described below, until it makes contact with a seal  56  at the opening of passageway  25 . The valve element  12  is a conventional type and comprises an operating end  12   a  (see  FIG. 2 ) which is struck by the hammer  6 , and an axial passageway  12   b  with a front opening facing passageway  25  and one or more rear openings that are blocked off by a seal  57  when the valve element  12  is in the resting position and which opens in the valve chamber  11  when the valve element  12  is in the firing position. 
   The upper section of barrel zone  1  also comprises a sliding cover  13  linearly guided to make a rocking movement in a direction parallel to the barrel  2  axis. The rear end of said sliding cover  13  includes links  14 ,  16  with said hammer  6 , which are described in more detail below with reference to  FIGS. 6 and 7  and are linked to said trigger  5  so that when the trigger is pressed, it moves the sliding cover  13  backwards, thus performing the actions of cocking and firing the hammer  6  through the motion of said links  14 ,  16  in synch with said backwards movement of the barrel  2 . A helicoidal compression spring  48  is arranged around the barrel  2  and compressed between the front interior end  13   a  of the sliding cover  13  and a surface of the support casing  26  or a body joined to this in order to push the sliding cover  13  forwards to the resting position. 
     FIGS. 5 and 6  show the installation of the trigger  5  in said trigger zone  4 . A pair of pieces  59 ,  60  shown in  FIG. 8 , facing each other, and joined together by means of screws  61  and fixed in place with respect to the casing  26 , define between them, a guide for barrel  2 , a housing  64  for a trigger piece  5   a  that is an integral part of the trigger  5 , and slots of guide  62 , into which are inserted protuberances  63  which laterally extend over said trigger piece  5   a  so that the same is able to slide into said housing  64  linearly guided by the guide slots  62  in a direction parallel to the barrel  2  axis. The trigger piece  5   a  comprises drag snugs  44 , preferably provided by the ends of a pin ( FIG. 8 ), which extend laterally from the same and interfere with internal stops  45  of the sliding cover  13  in order to drag it. Just as described above in reference to  FIG. 2 , the trigger piece  5   a  includes a cavity  46 , into which is inserted a catch  47  that is firmly attached to the barrel  2  in order to drag it. Between said catch  47  and wall contacts in said cavity  46 , is free play to permit a delay in the beginning of barrel  2  movement with respect to the start of trigger  5  movement and to guarantee less barrel  2  movement when trigger  5  is pressed as when it is free. 
     FIG. 5  also shows an automatic safety catch  39  linked to trigger  5  so that said safety catch  39  interferes with a fixed stop  41  inside the sliding cover  13  when trigger  5  in is said resting position ( FIG. 6 ), preventing any voluntary or involuntary movement of the sliding cover  13  independently of trigger  5  movement, which could produce firing. The catch  39  is separated from the path of said stop  41  by the trigger  5  when this is pressed ( FIG. 7 ), allowing movement of the sliding cover  13  by the trigger  5 . This automatic safety catch  39  is connected to the arm  40  installed on part  59  fixed to the casing  26  so that it is able to pivot with respect to axis  53 . Said arm  40  incorporates a linear guide  54 , along which snug  55  slides joined to the trigger  5  or trigger piece  5   a , by which a backwards movement of trigger  5  produces a downwards movement of automatic safety catch  39  just as shown by the broken lines in  FIGS. 5 ,  6  and  7 . 
     FIGS. 6 and 7  show said links  14 ,  16  of the sliding cover  13  with the hammer  6 . A pawl  14  is articulated by a pin  52  loaded by a spring  15  and a protuberance  16 , which extends laterally over the hammer  6 . The hammer  6  is mounted on the rear section of casing  26  so that it can pivot with respect to shaft  17  and is pushed by a spring  18  (see  FIG. 2 ) towards a position in which a stud  58  fixed at its distal end is in contact with the operating end  12   a  of the valve element  12 . In the resting position shown in  FIG. 6 , the sliding cover  13  is in its front position, the hammer  6  is in its position of contact and said pawl  14  is coupled with said protuberance  16  of the hammer  6 . When the sliding cover  13  is moved linearly backwards by the trigger  5 , said pawl  14  drags along said protuberance  16  and causes the hammer  6  to pivot backwards against the force of said spring  18  until it reaches the firing position shown in  FIG. 7 , in which, in virtue of the curved path of protuberance  16 , this escapes from the pawl  14  and spring  18  pushes the hammer  6  to cause said impact on said valve element  12 . Just as was described above, this is produced in synch with the movement of the barrel  2  in order to isolate the chamber  3 . When the trigger  5  is then freed, the sliding cover  13  returns to the resting position and forces the pawl  14  to exceed the protuberance  16 , pivoting against the force of spring  15 . 
   As shown in  FIG. 1 , the pistol comprises a voluntary safety element  42  mounted on the exterior of an upper section of the stock zone  7  so that it can be voluntarily pivoted between a locked position, in which a tooth  42   a  of said voluntary safety element  42  fits into a recess  43  in said sliding cover  13  and a free position in which said tooth  42   a  is not fitted into said recess  43 . By immobilising the sliding cover  13 , this voluntary safety element  42  prevents the operation of trigger  5  from producing firing of the pistol. Casing  26  of the pistol also includes longitudinal channels  65  on both lower sides of the barrel zone  1 , which are adapted for accepting various accessories. 
     FIG. 9  shows a casing  27 . The support casing  26  is hollow in the stock zone  7  (see  FIG. 2 ) and is open at the lower end to receive said casing  27 , which includes said ammunition magazine  8 , together with the chamber  3 ; a cavity  28  for housing the pressurised gas cylinder  10 , with a perforation needle  50  that perforates a gas exit in the pressurised gas cylinder  10 ; a valve body  29 , which defines said valve chamber  11 , and which holds said valve element  12 ; and a sliding protector  30  configured and arranged to cover said operating end  12   a  of the valve element  12  when said casing  27  is removed from the stock zone  7 . This sliding protector  30  is pushed by a spring  31  towards a position of protection, as shown in  FIG. 9 , in which one end of the sliding protector  30  covers the operating end  12   a  of the valve element  12 , thus preventing any involuntary operation of the valve element  12  that could cause an unintended expulsion of the pellet  9   a  located in the chamber. Inside the stock zone  7  (see  FIG. 2 ) is a stop  32 , which makes contact with the sliding protector  30  and holds it in a retired position against the force of said spring  31  when the casing  27  is installed in the stock zone  7 . A retainer  33 , which is of a known type, is arranged in the support casing  26  (see  FIG. 1 ) so that it can be operated from the exterior in order to retain the casing  27  in the stock zone  7  against the force of the spring  31 . When said retainer  33  is freed in order to extract the casing  27 , the sliding protector  30  acts as an expulsion mechanism in virtue of the force provided by the spring  31 . 
   Casing  27  also comprises a lower cover  34  articulated with respect to a shaft  36  and fitted with an elastic lock catch  37 . Said lower cover  34  defines an interior cavity for housing and protecting, when in a closed position, a lock wing nut  38  for the pressurised gas cylinder  10 . As can be better appreciated in  FIGS. 1 and 2 , the lower cover  34  defines an exterior surface that extends and ends below an exterior surface of said hollow casing  26  in the stock zone  7 , when the casing  27  is installed in the stock zone  7 . 
   One skilled in the art could introduce modifications or variants without leaving the scope of this invention as defined in the included claims.