Abstract:
A paintball gun which is simplified in structure and improved in gas efficiency comprises a two-stage pneumatic propulsion, a rear end of the paintball feeder is engaged in an inner groove of the pushing rod, such arrangements facilitates smooth flow of the gas in the barrel of the paintball gun and simplification of the structure.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a paintball gun. 
   2. Description of the Prior Art 
   In order to improve the gas efficiency and power of a paintball gun, someone has proposed to make a two-stage pneumatic propulsion device to increase the firing power. 
   Referring to  FIG. 1 , a conventional paintball gun  1  with a two-stage pneumatic propulsion device is shown and comprises a barrel  2  in which a pushing rod  4  and a paintball feeder  5  are disposed. Furthermore, the barrel  2  is connected to one end of a valve by a passage  6 , and the other end of the valve is connected to an air supply portion. 
   The pushing rod  4  is a conical structure in the outer surface of which is defined an air guiding route  8  connected to the rear end of the pushing rod  4 . The rear end of the pushing rod  4  is formed with a first protruding portion  9  and a positioning portion  10  extending from the first protruding portion  9 . The positioning portion  10  abuts against a cover so as to define a first gas chamber  12  between the cover  11  and the pushing rod  4 . In the barrel  2  is formed a first stop portion  13 , and at the rear end of the first stop portion  13  is further defined a through hole  14  which is communication with the interior space of the barrel  2  and the passage  6 , so that the gas of the passage  6  can be pushed to the rear end of the pushing rod  4  via the through hole  14 , and the pushing rod  4  moves along a first travel path between a first position and a second position. 
   The paintball feeder  5  is defined with a gas channel  15  in communication with the muzzle of the gun, and the pushing rod  4  is abutted against the rear end of the paintball feeder  5  so as to close the gas channel  15 . The paintball feeder  5  includes a second protruding portion  16 , and in the barrel  2  is further formed a second stop portion  17 . The paintball feeder  5  is allowed to move along a second travel path between a first position and a second position. 
   When the valve is opened, gas will be supplied from the air supply portion via the passage  6  to push the pushing rod  4  to the second position from the first position, and the front end of the pushing rod  4  will simultaneously push the paintball feeder  5  to move from the first position to the second position, indirectly making the paintball feeder  5  propel the paintball. Since the second travel path is longer than the first travel path, the first protruding portion  9  will be pressed against the first stop portion  13  as the pushing rod  4  moves to the second position. At this moment, the gas will keep pushing the rear end of the paintball feeder  5  to move forward, thus opening the gas channel  15  and creating a strong firing power. 
   However, since such a paintball gun is provided with a passage outside the pushing rod for the flow of the gas, it must arrange an inner pipe inside the barrel to restrict the flowing route of the gas. Moreover, friction will be caused when the gas flowing through the unsmooth inner surface of the inner pipe, thus reducing the gas efficiency. 
   The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
   SUMMARY OF THE INVENTION 
   The primary objective of the present invention is to provide a paintball gun. The paintball comprises a barrel and a valve. The valve is provided with a passage for allowing gas to flow to the barrel. In the barrel is disposed a paintball feeder and a pushing rod, in the paintball feeder is defined a gas channel for allowing gas to be outputted from the passage, the pushing rod is abutted against a rear end of the paintball feeder to close the gas channel. Gas from the passage is able to flow to a rear end of the pushing rod to push the pushing rod to move within a first travel between a first position and a second position. The paintball feeder is able to move along a second travel between a third position and a fourth position. The first travel is longer than the second travel, so when the pushing rod is pushed to the second position, the paintball feeder will be pushed by the gas of the passage to move away from the pushing rod and to open the air channel, so that the gas of the passage will be outputted from the air channel to fire the paintball. The paintball gun is characterized in that: a front end of the pushing rod is formed with an inner groove, and the pushing rod is further provided with a hole for connecting the inner groove and the rear end of the pushing rod, an inner diameter of the inner groove is larger than an outer diameter of the paintball feeder, the rear end of the paintball feeder is engaged in the inner groove. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view of a conventional paintball gun; 
       FIG. 2  shows a paintball gun in accordance with the present invention; 
       FIG. 3  shows the non-firing state of the paintball gun in accordance with the present invention; 
       FIG. 4  shows the ready-to-fire state of the paintball gun in accordance with the present invention; 
       FIG. 5  shows the firing state of the paintball gun in accordance with the present invention; and 
       FIG. 6  shows that the paintball gun in accordance with the present invention returns to the non-firing state. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
   Referring to  FIGS. 2 and 3 , a paintball gun in accordance with the present invention comprises a barrel  20  and a valve  40 . The valve  40  is provided with a passage  41  for allowing the gas to flow to the barrel  20 . In the barrel  20  are further disposed a paintball feeder  21  and a pushing rod  22 . In the paintball feeder  21  is defined a gas channel  211  for allowing gas to be outputted from the passage  41 . In the front end of the pushing rod  22  is formed an inner groove  221 , and the pushing rod  22  is further provided with a hole  222  for connecting the inner groove  221  and the rear end of the pushing rod  22 . The inner diameter of the inner groove  221  is larger than the outer diameter of the paintball feeder  21 . The rear end of the paintball feeder  21  is engaged and positioned in the inner groove  221  to close the gas channel  211 . Moreover, the pushing rod  22  includes a first protruding portion  223 , the paintball feeder  21  includes a second protruding portion  212 , and in the barrel  20  are formed a first stop portion  23  and a second stop portion  24 . The first protruding portion  223  is abutted against the first stop portion  23 , and the second protruding portion  212  is rested against the second stop portion  24 . In the barrel  20  is further provided a separating board  25  which is located at the rear end of the pushing rod  22 . A first gas chamber  26  is defined between the pushing rod  22  and the separating board  25 . The vertical contacting surface of the pushing rod  22  with respect to the first gas chamber  26  is defined as a first pushing surface  27 . A second gas chamber  28  is defined between the inner groove  221  and the rear end of the paintball feeder  21 , and a vertical contacting surface at the rear end of the paintball feeder  21  for contacting the second gas chamber  28  is a second pushing surface  29 . The front end of the second protruding portion  212  is a stepped structure, between the second protruding portion  212  and the second stop portion  24  is defined a third gas chamber  30 , and the vertical contacting surface of the second protruding portion  212  for contacting the third gas chamber  30  is a third pushing surface  31 . The first pushing surface  27  is larger than the second pushing surface  29 , and the second pushing surface  29  is larger than the third pushing surface  31 . In this present invention, the vertical contacting surface is defined as the contacting surface which is vertical to the length direction of the barrel. 
   Furthermore, the valve  40  is defined with a front groove  42 , a rear groove  43 , a first groove hole  44 , a second groove hole  45  and a discharge hole  46 . The first groove hole  44  is connected to an air supply portion, the second groove hole  45  is in communication with the passage  41 , and the discharge hole  46  is connected to outside. The third gas chamber  30  is defined with an air supply passage  32  which is connected to the air supply portion for continuously providing a propulsion to the third pushing surface  31 . 
   For a better understanding of the firing operation of the present invention, reference should be made to  FIGS. 3-6 . Referring first to  FIG. 3 , before firing (non-firing state), the gas flows from the air supply passage  32  to the third gas chamber  30  to provide a push force toward the third pushing surface  31 , enabling the paintball feeder  21  and the pushing rod  22  to move to the first position in the second travel and the first position in the first travel. At this moment, the paintball to be fired is able to move to the front end of the paintball feeder  21  via the paintball feeding port. Referring then to  FIG. 4 , when the paintball gun  1  is in the firing state, the front groove  42  is in communication with the first groove hole  44  and the second groove hole  45 , at this moment, the gas supplied from the air supply portion will flow along the passage  41  into the first gas chamber  26  at the rear end of the pushing rod  22  and push the pushing rod  22  to move to the second position in the first travel, namely, the first protruding portion  223  will be abutted against the first stop portion  23  while pushing paintball feeder  21  to move forward to close the paintball feeding port. Referring further to  FIG. 5 , while pushing the pushing rod  22  to move, the gas of the first gas chamber  26  will also flow through the hole  222  into the second gas chamber  28  to push the paintball feeder  21  to the second position in the second travel, namely, the second protruding portion  212  will be abutted against the second stop portion  24  while opening the gas channel  211 , so that the gas of the passage  41  will flow into the gas channel  211  to fire the paintball. Finally, referring to  FIG. 6 , the instant the firing is completed, the valve  40  will return to its non-firing state, allowing the rear groove  43  to be communicated with the second groove hole  45  and the discharge hole  46  while releasing the air pressure of the first gas chamber  26  and the second gas chamber  28 . Furthermore, at this moment, since the gas of the third gas chamber  30  still keeps providing a pushing force toward the third pushing surface  31 , it definitely will push the paintball feeder  21  and the pushing rod  22  to move backward to the first position in the second travel and to the first position in the first travel, namely, making the paintball gun  1 ′ return to the non-firing state. 
   As compared to the conventional two-stage pneumatic propulsion type paintball gun, the present invention has the following advantages: 
   First, inside of the pushing rod is defined the passage in communication with the first and second gas chambers, therefore, the diameter, size, surface-smoothness of the passage can be more precisely controlled, thus avoiding the loss of gas efficiency. 
   Second, the passage of the conventional pushing rod is defined by the outer surface of the pushing rod and the inner pipe outside the pushing rod, therefore, it needs an inner pipe to restrict the air-flow direction of the gas flowing through the passage. However, the pushing rod of the present invention is defined with an inner groove, and the passage is also located inside the pushing rod, hence, the present invention does not need an extra inner pipe, thus simplifying the structure while reducing the production cost. 
   Third, the front end of the second protruding portion is a stepped structure, the purpose of such a structure is that when a part of the second protruding portion is abutted against the second stop portion, gas can still flow through the air supplying passage into the third gas chamber while providing a pushing force toward the third pushing surface, so as to push the paintball feeder backward without requiring an extra spring to push the paintball feeder to move backward. Except improving the gas efficiency, such a structure also contributes to simplify the assembly and cost of the paintball gun. 
   While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.