Patent Publication Number: US-6904902-B2

Title: Airgun with airflow control

Description:
FIELD OF THE INVENTION 
     The present invention relates to an airgun, such as an air rifle or air pistol, comprising a valve intended to be in contact with a compressed air cartridge, a barrel into which a bullet is insertable, and a passageway connecting the valve with the barrel. 
     BACKGROUND ART 
     Airguns of the above type operated by compressed air from a cartridge which is connected to the airgun are well known. Owing to the relatively great pressure in the cartridge, the airgun can be fired with great accuracy also at a long range. This great pressure, however, is not always necessary, and then there may be a need for controlling the airflow through the passageway which extends from the air cartridge to the bullet. 
     In the air pistol disclosed in U.S. Pat. No. 5,333,594, an adjustable screw is arranged to offer a possibility of adjusting the air pressure. Similar adjusting screws may be used in air rifles. 
     However, such an adjusting screw has several drawbacks. First, the screw must be relatively firmly tightened so as to prevent gas from leaking through the thread, and therefore some kind of implement is usually required to turn the screw (poor user-friendliness). Second, it is difficult for the user to determine how the screw is set by observing it. Instead it is necessary to fire a trial shot in order to assess whether an adjustment is necessary (poor efficiency). Third, it is difficult to repeat a change of the setting with sufficient accuracy (poor repeatability). 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide an air-operated gun which offers a different possibility of controlling the airflow. 
     This and other objects are achieved by a gun of the type mentioned by way of introduction, further comprising a flow-controlling element with a plurality of through holes of different diameters, said element being arranged in the passageway so that a part of the element comprising at least one of said holes extends transversely of the passageway. 
     The diameter of the hole or holes that is/are positioned in the passageway thus defines the effective cross-section of the passageway and, thus, the flow through the passageway. This means that the invention offers an improved possibility of controlling the airflow. 
     The element can be movably arranged in the passageway to enable selective insertion of one of said holes into the passageway. In this manner, a plurality of different distinct positions can be set, each with an unambiguously defined flow. 
     According to one embodiment of the invention, the element is disc-shaped and is arranged rotatably in its horizontal plane. By rotating the disc, the user can insert a selected hole into the passageway. 
     Suitably a part of the element extends outside the body of the airgun, so as to be accessible from the outside of the airgun. The element may thus be operated by contact with this part, for instance by the user using the thumb or index finger of his one hand. This eliminates the need for special implements. 
     Preferably, the disc-shaped element is arranged to take predetermined positions, in which a hole is inserted into the passageway. Thus the user runs a smaller risk of inadvertently placing the element in an incorrect position. Such an arrangement can be achieved, for instance, by notches along the periphery of the element which coact with a catch. 
     Preferably, the disc-shaped element is provided with external marks, which are visible to the user and which indicate which hole/holes is/are positioned in the passageway. This makes it possible for a user to be quite sure about which flow for the time being is set by means of the flow-controlling element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A currently preferred embodiment of the invention will now be described in more detail with reference to the accompanying drawings. 
         FIG. 1  shows partly in cross-section part of an airgun provided with a flow-controlling element according to the invention. 
         FIG. 2  is a perspective view of part of the airgun in  FIG. 1 , comprising the element. 
         FIG. 3  shows an enlarged part of FIG.  1 . 
     
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT 
     The airgun shown in  FIGS. 1-3  comprises a butt  1  and a barrel  2 . The butt comprises an upper and a lower block  4 ,  5 . The lower block has a connection  6  to allow connection of a cartridge (not shown) for pressurised gas, usually air. The connection  5  of the cartridge is, via a valve  7  accommodated in the block  5 , connected with a passageway  8  extending through the blocks  4  and  5  up to the bore  3  of the barrel  2 . The passageway leads to a position where a bullet  10  located in a charging compartment  9  can be inserted by a feeding pin  11 . 
     The block  5  also has a space  12  behind the valve  7  in which a hammer  13  is slidably movable between a first position in which it is lockable by means of a hook  14  (see FIG.  1 ), and a second position in which it strikes against the valve cone of the valve  7  (see FIG.  2 ). The hammer  13  is spring-loaded towards the valve  7  by means of a helical spring  15 . A cock  16  is arranged in connection with the hook  14  in order to actuate the hook  14  to release the hammer  13 . 
     With reference to  FIG. 2 , it is shown more distinctly how the valve  7  has a valve cone  20  which in a spring-loaded manner seals against a seat  21 . The valve cone has a rear portion  20   a  extending a distance outside the valve  7  into the space  12 . 
     According to the invention, a flow-controlling element  22  is further arranged in the passageway  8 . The element  22 , which is mounted between the blocks  4  and  5 , is sealed against the block  4  and the block  5 , respectively, by means of two O rings  18 ,  19  extending round the passageway  8 . 
     The element, which is best seen in  FIG. 3 , comprises in the illustrated embodiment a disc  23  with a plurality of through holes  24  of different sizes. In  FIG. 3 , the disc  23  is rotatably arranged in the upper block  4  by means of a pin  25  or the like. The disc is arranged at the underside of the block  4  so that a part of the disc  23 , with at least one hole  24 ′, extends over the entire cross-section of the passageway  8 . This hole  24 ′ thus forms part of the extension of the passageway  8  and reduces the effective cross-section thereof, i.e. throttles the flow through the passageway. By rotating the disc, a selected hole can be inserted into the passageway  8 . 
     As is also shown in  FIG. 3 , a part  26  of the disc  23  extends a distance outside the side of the block  4 , which makes it accessible for operation by a user, using for instance his finger. Conveniently the disc  23  is further provided with notches  27  which may cooperate with a resilient catch  28 . Thus the disc is rotatable between a plurality of discrete positions, each corresponding to a location of a predetermined hole  24  in the passageway  8 . Marking of the side of the disc  23  makes it possible for a user to know which hole  37  is Placed in the passageway and, thus, the cross-section of the passageway. 
     An operating handle  30  is arranged to move a driver  31  rearwards to the barrel by the user making a pivoting motion. The driver  31  is arranged to drive, in its rearward motion, the hammer  13  and the feeding pin  11 . 
     When using the airgun, the operating handle  30  is moved outwards and rearwards, whereby the driver  31  drives the hammer  13  against the action of the spring  15  to its rear position where it is locked by the hook  14  (see FIG.  1 ). At the same time the feeding pin  11  is moved backwards, past the compartment  9 , and thus enables the insertion of a bullet  10  into the compartment  9  (see FIG.  1 ). Subsequently the operating handle  30  is returned to its starting position, the hammer  13  being retained by the hook  14 , while the feeding pin  11  is returned to its front position ( FIG. 2 ) and, thus, presses the bullet  10  into the bore  3 . The airgun is now loaded. 
     When the cock  16  is then pressed, the hook  14  is allowed to release the hammer  13  which is pressed forward to the valve  7  by means of the spring  15 . When the hammer  13  strikes against the projecting portion  20   a  of the valve cone  20 , the valve cone is moved from its closed position against spring action, and air is allowed to pass the valve and through the passageway  8  up to the bore  3 . This flow of air is best seen in  FIG. 2 , reference numeral  32 . As soon as the motion of the hammer  13  has been braked, the valve cone  20  is caused to return to its closed position by the spring force. It is the amount of air that has passed the valve  7  which causes firing of the bullet  10 . 
     On its way through the passageway  8 , the flow of air passes through that hole  24 ′ in the disc  23  which is positioned in the passageway  8 . The size of this hole determines the size of the flow and, thus, the force that will act on the bullet  10 . 
     Between shots, a user may rotate the disc  23  by contacting the part  26  and, thus, change the flow that can pass through the passageway  8 . This allows easy trimming of the airgun according to the conditions. For instance, it may be convenient to insert a larger hole  24  when firing at a long range. 
     It should be noted that the shape of the element  22  may be varied. For example, a long narrow sheet with holes arranged in a row may be slidingly arranged in the passageway, so that a user, by moving the sheet to the correct position, may insert the desired hole into the passageway. It is also possible to fixedly arrange the element  22  in a predetermined position, e.g. by means of a screw. Although this reduces the flexibility for the user, it may in some situations be desirable.