Abstract:
A gas powered gun comprising a valve arranged to exhaust compressed gas from a chamber to thereby discharge a projectile inside a barrel, and a hammer arranged to be cooperate with a valve opening arrangement to thereby open the valve. A spring is arranged between the hammer and a spring abutment for spring loading the hammer. The gun further comprises an adjustment knob turnable around an axis A of rotation, substantially perpendicular to the spring loading direction. The knob has a cam surface having a varying radial distance from the axis of rotation, and a follower, integrated with the spring abutment, is pressed by the spring to rest against the cam surface. When the adjustment knob is turned, the follower will slide against the cam surface and move the follower and the spring abutment in the spring loading direction, to thereby adjust a pretension of the spring.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of, and priority to, European Patent Application No. 15157145.2 filed Mar. 2, 2015. The entire disclosure of the above application is incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a gas powered gun having a valve arranged to exhaust compressed gas from a chamber to thereby discharge a projectile inside a barrel, a hammer arranged to be cooperate with a valve opening arrangement to thereby open the valve, a spring abutment, and a spring arranged between the hammer and the spring abutment and arranged to spring load the hammer in a spring loading direction towards the valve opening arrangement. 
       BACKGROUND OF THE INVENTION 
       [0003]    Gas powered guns of the above mentioned kind are well known in the art, and the compressed gas may be e.g., air (air guns). 
         [0004]    The tension of the spring will determine the force of the hammer, and thus the time during which the valve is open. The stronger the spring force, the longer the valve will stay open, and the more gas will be exhausted into the barrel. And the more air, the higher speed of the discharged projectile. 
         [0005]    Therefore, it is known to adjust the tension of the spring, typically by moving the spring abutment against which the spring rests. Typically such adjustment requires specific tools, and is only done during manufacturing. 
         [0006]    However, there is an increased need or desire to provide more simple adjustment of the discharge speed. 
       General Disclosure of the Invention 
       [0007]    This and other objects are achieved by a gas powered gun for discharge of projectiles, comprising a valve arranged to exhaust compressed gas from a chamber to thereby discharge a projectile inside a barrel, a hammer arranged to be cooperate with a valve opening arrangement to thereby open the valve, a movable spring abutment, and a spring arranged between the hammer and the spring abutment and arranged to spring load the hammer in a spring loading direction towards the valve opening arrangement. The gun further comprises an adjustment knob including a gripping portion, allowing a user to grip the adjustment knob and to turn the adjustment knob around an axis of rotation, the axis of rotation being substantially perpendicular to the spring loading direction, and a cam surface extending around the axis of rotation and having a varying radial distance from the axis of rotation, and a follower, integrated with the spring abutment and pressed by the spring in the spring loading direction to rest against the cam surface, so that, when the adjustment knob is turned, the follower will slide against the cam surface and move the follower and the spring abutment in the spring loading direction, to thereby adjust a pretension of the spring 
         [0008]    According to the invention, the spring abutment, and thus the compression of the spring, can be easily adjusted by turning the knob. More specifically, depending on the rotational position of the knob, the portion of the cam surface facing the follower will have a different distance to the axis of rotation, and the follower, which is pressed against the cam surface, will thus assume a different position in the spring loading direction. As the abutment is attached to the follower, also the position of the abutment will be changed. The position of the abutment will determine a distance between the abutment and the hammer, and thus the compression of the spring. The compression of the spring will determine the force of impact of the hammer on the valve opening arrangement, which in turn will determine the duration of time during which the valve is open. The longer the valve is open, the more compressed gas will enter the barrel, and the higher the velocity of the discharged bullet will be. 
         [0009]    The expression “coupled with” is intended to include all designs where movement of the follower will lead to movement of the abutment. For example, the abutment and follower may integrally formed as one single element. They may also be formed as two elements, fixedly attached to each other. More complex alternatives are also possible, where the follower and abutment are mechanically linked by intermediate members. 
         [0010]    The knob is preferably arranged so as to be easily accessible from outside the gun, i.e. without requiring any dismantling of the gun or any special tools. 
         [0011]    The cam surface may be the mantle surface of a cylindrical portion formed with a center axis in parallel and at a distance from the axis of rotation. This is a simple and effective way to design and manufacture a knob with a cam surface according to the invention. It means that the cylindrical portion is asymmetrically arranged around the axis of rotation of the knob. 
         [0012]    The knob can be lockable in predefined positions, each position associated with a specific portion of the cam surface facing the follower, each cam surface portion having a specific distance to the axis of rotation. This makes it very easy for a user to select a desired velocity by turning the knob to one of the positions. For example, the knob may include a plurality of indentations in a surface facing the gun, and a spring loaded rounded surface arranged to slide against the surface and to engage one of the indentations, to thereby lock the knob in one of the plurality of predefined positions. 
         [0013]    Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the [element, device, component, means, step, etc.]” are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above, as well as additional objects, features and advantages of the present disclosure, will be better understood through the following illustrative and non-limiting detailed description of currently preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements. 
           [0015]      FIG. 1 a    is a cross section of a portion of an air gun according to an embodiment of the present invention, in a ready-to-fire state. 
           [0016]      FIG. 1 b    is a more detailed cross section of the rear portion of the gun in  FIG. 1   a.    
           [0017]      FIG. 2 a    is a cross section of the portion in  FIG. 1 a   , after the trigger has been activated. 
           [0018]      FIG. 2 b    is a more detailed cross section of the rear portion of the gun in  FIG. 2   a.    
           [0019]      FIG. 3 a    is a more detailed cross section of the middle portion of the gun in  FIG. 1   a.    
           [0020]      FIG. 3 b    is a side view of the middle portion of the gun in  FIG. 1 , seen from the opposite side. 
           [0021]      FIG. 4  is an exploded view of the bullet velocity regulator arrangement in  FIG. 3 a   - 3   b.    
           [0022]      FIGS. 5 a  and 5 b    are plane views showing the operation of selected parts of the velocity regulator in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0023]    Embodiments of the present disclosure will be described in more detail in the following with reference to the accompanying drawings. All the figures are highly schematic, not necessarily to scale, and they show only parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested. 
         [0024]      FIGS. 1 a , 1 b , 2 a , 2 b    show a gas powered gun  1 .  FIGS. 1 a  and 1 b    show the gun in a ready-for-fire-position, while  FIGS. 2 a  and 2 b    show the gun after the trigger has been activated. The same reference numerals have been used to indicate identical elements in all drawings  1   a ,  1   b ,  2   a,    2   b.  In the following description, the expressions front and rear relate to the normal firing direction of the gun, and consequently “rear” is to the left in  FIG. 1  a, while “front” is to the right in  FIG. 1  a. 
         [0025]    The portion of the gun  1  shown in  FIGS. 1 a , 2 a    comprises a front portion  10 , where a container  2  of compressed air or other gas is fitted to the body  3  of the gun  1 . A connector  7  is arranged between the bottle  2  and the gun  1  and it is used to fill the bottle  2  with gas. The gun  1  also has a rear portion  30 , where a butt  5  is fitted to the body  3 , and a central portion  20  between the front portion  10  and the rear portion  30 . A barrel  4  is fitted in the body  3  so as to extend from the rear portion  30  through the central and front portions  20  and  10 . The front end of the barrel  4  is not shown in the figures. 
         [0026]    A feeder pin  6  is slidably arranged in the body  3  immediately behind the rear end  4   a  of the barrel  4 . The feeder pin  6  is arranged to push a projectile e.g., in the form of a diabolo bullet  12 , from a magazine (not shown) into the barrel  4 . The feeder pin  5  is arranged to be slid back and then to be slid forward, in order push a projectile e.g., in the form of a diabolo bullet  12 , from a magazine (not shown) into a firing position in the barrel  4 , as shown in  FIGS. 1 a    and  1   b.    
         [0027]    The compressed gas from the container  2  is fed to a pressure chamber  11 . The pressure chamber  11  is an elongated chamber which extends from rear portion  30  towards the central portion  20  of the gun  1 . The gun  1  further comprises an open-close valve  60 , which is arranged in the rear end of the pressure chamber  11 . In its closed state, the valve  60  seals the pressure chamber  11 . In its open sate, the valve allows passage of compressed gas from the bottle  2  to a space  10  immediately behind the bullet  12  in the barrel  4 . 
         [0028]    As will be described in more detail below, the valve  60  is opened by a valve opening arrangement cooperating with a spring loaded hammer  9 , which is released by a trigger  15 . When the valve  60  is opened, compressed air from the chamber  11  is exhausted into the space  10  behind the bullet  12  and “fires” the bullet  12 . 
         [0029]    The gun  1  may also comprise a gas regulator  16 , which also is arranged at the central portion  20  of the gun  1 . A regulator is a mechanical device, i.e. a valve that controls the air pressure in the pressure chamber  11 . A passage (not shown) in the gun body  3  forwards the gas from the container  2  into the regulator  16 , which forwards the gas into the pressure chamber  11  and regulates the gas pressure in the pressure chamber  11 . This means that the pressure is always the same and hence an airgun with a regulator shoots with very consistent velocity. 
         [0030]    The pressure chamber  11  is here formed by a rear hollow cylinder portion  40 , and a front hollow cylinder portion  50  sealingly joined together to a continuous cylindrical compartment. In the illustrated example, the rear end of the front hollow cylinder portion  50  threadedly engages the front end of the rear hollow cylinder portion  40 . A sealing member  48 , e.g. an o-ring, is arranged to seal between the two cylinder portions  40 ,  50 . 
         [0031]    With reference to  FIG. 1 b   , the rear hollow cylindrical portion  40  comprises a front portion  41  in its front end, a middle portion  42  immediately behind the pressure chamber, and a rear portion  43  in its rear end. The rear portion  43  has an inner diameter which is smaller than the inner diameter of the middle and front portions  42 ,  41 . Preferably, the inner diameter of the middle portion  42  is slightly smaller than the inner diameter of the front portion  41 . The front hollow cylindrical portion  50  comprises a rear portion  51  and a front portion  52 . The inner diameter of portion  51  is larger than the inner diameter of portion  52 . 
         [0032]    The front portion  41  of the rear hollow cylindrical portion  40  and the rear portion  51  of the front hollow cylindrical portion together form the pressure chamber  11 . The middle portion  42  is in fluid connection with the space  10  via a channel  49  extending perpendicularly to the centre axis A of the pressure chamber  11 . 
         [0033]    With continued reference to  FIG. 1 b   , the open-close valve  60  comprises a valve seat  44  arranged between the front and middle portions  41 ,  42  of the rear hollow cylindrical portion  40 . The valve seat  44  may be arranged to abut against an annular step  45  formed by any difference in inner diameters. The valve  60  further comprises a valve head  62  which has an annular flange  61  arranged to cooperate with the valve seat  44 . 
         [0034]    The valve head  62  is here arranged in front of the valve seat  44 , and is arranged at one end of a rod  63 . The rod  63  forms an elongated extension of the valve head essentially in the longitudinal direction A towards the front of the gun  1  through the pressure chamber. In the illustrated example, the rod  63  and the valve head portion  62  are interconnected by means of a threaded sleeve  65 . More specifically, the rod  63  and the valve head  62  each comprises threaded portions  66 ,  67  at the ends which shall be connected. The threaded portion  66  of the valve head  62  and the threaded portion  67  of the rod  63  are threadedly engaged to opposite ends of the sleeve  65 . 
         [0035]    The rear end  72  of the valve head  62  is received in the rear portion  43  of the rear hollow cylinder portion  40 , and serves to guide the valve head  62  and the rod  63 . The end  72  is further sealed against the inner walls of portion  43 , here by means of an O-ring  80 . At the front end of the pressure chamber  11  the rod  63  protrudes out of the pressure chamber  11  through the front portion  52  of the front cylinder portion  50 . The rod  63  is sealed against the inner walls of the portion  52 , here by means of an O-ring  81 , in order to seal the front end of pressure chamber  11 . It is noted that the diameter of the flange  61  is larger than the diameter of the rod  63  where it seals the pressure chamber  11 . A pressure in the pressure chamber will therefore serve to press the valve head  62  against the valve seat  44  to effectively seal the chamber  11 . 
         [0036]    A hammer cooperating member  68  is connected to the front end of the rod  63 . In the illustrated example, the rod  63  comprises at this end a threaded portion  69  which engages a threaded hole in the hammer cooperating member  68 . The hammer cooperating member  68  comprises a larger diameter hammer hitting portion  70  and a smaller diameter guiding portion  71 . 
         [0037]    The guiding portion  71  is received in a support  90 . The support  90  comprises a spring abutment,  92 . A spring  93  is arranged between this spring abutment  92  and the hammer hitting portion  70  of the hammer cooperating member  68 . The spring will serve to press the hammer cooperating member  68  and the extension member  61  in the rearwards direction, to close the valve  60  after the gun has been fired, further described below. 
         [0038]    The hammer  9  is arranged between the pressure chamber  11  and the hammer cooperating member  68 . In the illustrated example, the hammer  9  has a central though hole  21 , through which the extension member  61  passes, to allow the hammer  9  to slide along the extension member  61 . In its rear end  9   a,  the hammer has a compartment for receiving one end of a coil spring  22 , which is arrange coaxially with the extension member  61 . The other end of the coil spring  22  abuts a spring abutment, here in the form of a cylindrical cup  23 . The rod  63  passes through a central through hole  24  in the cup  23 , allowing relative motion between the rod  63  and the cup  23 . The cup  23  is fixed with respect to the frame  3 , but its position may be adjustable. A catch  25  engages the lower edge  26  of the hammer  9 . The catch  25  is mechanically connected to the trigger  15 . The trigger-catch cooperation can be done in many different ways and will not be explained further. 
         [0039]    In  FIG. 1 a  and 1 b   , the gun is in a loaded position, i.e. in a ready-for-fire-position. As mentioned above, the feeder pin  6  has been slid into the barrel  4 , and fed a bullet  12  into the firing position. The hammer  9  is spring loaded by the spring  22  against the catch  25 , and the valve  60  seals the pressure chamber  11 . The pressure chamber  11  has been filled with high pressure air from the bottle  2 , with a pressure regulated by the regulator  16 . 
         [0040]    With reference to  FIGS. 2 a  and 2 b   , when the hammer  9  is released by actuating the trigger  15 , the hammer  9  is forced by the spring  22  into contact with the hammer cooperating member  68 . By the impact, the hammer cooperating member  68  will move in the forward direction (to the right in  FIG. 2 a   ) and the rod  63  and the valve head  62  will move with it. The hammer  9  will thus “pull” the valve head  62  out of sealing contact with the valve seat  44  to thereby allow an exhaust of gas through the channel  49  into the space  10  behind the bullet  12 . As a consequence, the bullet  12  will be discharged through the barrel  4 . 
         [0041]    When the hammer cooperating member  68  is pushed forward by the hammer  9 , the spring  93  will be compressed. After impact, the spring  93  will return the hammer cooperating member  68 , the rod  63  and the valve seat  62  to their original position (as in  FIG. 1 a , 1 b   ), to close the valve  60 . 
         [0042]    When the bullet has been discharged, the pressure in the pressure chamber  11  will immediately drop and the regulator  16  will allow new gas to flow from the gas bottle  2  into the pressure chamber  11  to bring the pressure back to its regulated value. The pressure in the pressure chamber  11  will press the valve head  62  against the valve seat  44  to tightly seal the pressure chamber  11 . 
         [0043]    The user may now use a manual handle (not shown) to bring the hammer back against the force of the spring  22  to its ready-to-fire state, where it is again secured by the catch  25 . 
         [0044]    The gun is here further provided with a velocity regulator arrangement  31 , shown partly in  FIG. 3 b    and in more detail in  FIG. 4 , which is arranged to allow a user to adjust the velocity of a bullet leaving the gun. 
         [0045]    The arrangement  31  comprises a follower  32  attached to the spring abutment  23  by means of a screw  33 . The follower  32  has a threaded bore  34 , in which a threaded pin  35  is engaged. The bore  34  extends in the spring loading direction and the pin  35  protrudes on the front side  32   a  of the follower  32 . The arrangement  31  further comprises an adjustment knob  36 , rotatably arranged in the body  3  of the gun immediately in front of the follower  32 . The knob  36  has a gripping portion  37  to enable a user to turn the knob  36  around an axis A, which is perpendicular to the spring loading direction C. The knob  36  further has a cylindrical portion  38 , arranged with its centre axis B parallel to axis A but offset with respect to axis A. As a result, different parts  39   a,    39   b  of the mantle surface  39  of the portion  38  will be at different distances to the axis A. It is noted that the offset of the axis should be smaller than the radius of the cylindrical portion  38 . 
         [0046]    The follower  32  and the knob  36  are oriented such that the follower  32  can slide in the spring loading direction C and the pin  36  can be brought into contact with the cam surface  39 . The spring  22  will press the abutment  23 , and thus the follower  32 , against the cam surface  39 . 
         [0047]    As illustrated in  FIGS. 5 a  and 5 b   , the rotational position of the knob  36  will change the position of the follower  32 , and thus the spring abutment  23 .  FIG. 6A  shows the follower more forward (left in the figure) while  FIG. 6B  shows the follower more rearward (right in the figure). 
         [0048]    In  FIG. 5 a   , the knob  36  is arranged such that the surface  39   a  of the cylindrical portion facing the follower  32  is close to the axis A. The pin  36  of the follower  32 , which rests against the cam surface  39   a,  is therefore in a forward position. 
         [0049]    In  FIG. 5 b   , the knob  36  has been turned 180 degrees, so that the surface  39   b  of the cylindrical portion facing the follower  32  is more distant from the axis A. The pin  36  of the follower  32 , which here rests against the cam surface  39   b,  is therefore in a rearward position. 
         [0050]    It is noted that the position of the pin  35  of the follower  32  will determine the exact position of the spring abutment  23  when the follower  32  abuts the cam surface  39 . The velocity regulator may thus be calibrated by turning the pin  35  in its threaded hole. Such calibration s typically only required during manufacturing or service of the gun. 
         [0051]    Returning to  FIG. 4 , the knob  36  is formed with a plurality of indentations  27  in the surface facing the body  3  of the gun. Further, a small pin  28 , or ball, is arranged in a groove or hole in the body  3 , and spring loaded by a spring  29  against the knob  36 . The pin  28  is pressed by the spring  29  into the indentation  27 , thereby locking the knob  36  in a predefined position. When the knob is turned, the rounded surface of the pin will slide out of the indentation and then against the surface of the knob until it engages another one of the indentations. In this way, the knob can be locked in one of a plurality of predefined positions. 
         [0052]    The effect of turning the knob  36  to the position in  FIG. 6A , is that the follower  32 , which is attacked to the spring abutment  23 , will pull the spring abutment forward, thus compressing the spring  22 . The spring loading of the hammer  9 , and thus the impact of the hammer  9  on the hammer cooperating member  68 , will then be stronger. With a stronger impact, the valve  60  will stay open a little longer, allowing more gas to flow into the discharge chamber  11 , and thereby increasing the velocity of the bullet  12 . 
         [0053]    The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, the valve head and hammer, which have been described as being located in front of the valve seat, may instead be located behind the valve seat, in a more conventional manner. In that case, the hammer may impact directly on the valve head, and push the valve open. The placement of the valve head, the hammer, the trigger and other elements of the gun will not affect the principles of the present invention, related to a novel velocity regulation arrangement.