Abstract:
A gas system for a firearm having a gas block coupled to a barrel with a gas capture port in communication with a barrel gas port. A sleeve removeably mounted inside the gas block has: a gas conduit; a seat near the gas conduit; a projection; and a rod conduit communicating gas through the projection. A rod movably mounted in the gas block has a cup fitting over the projection. 
     A valve has a knob coupleable to the gas block and a plug moveable within the pressure sleeve with a plunger engageable with the seat to adjust gas flow through the gas conduit to the rod conduit. Gas discharged from a fired cartridge flows against the cup to drive the rod to reload the firearm. The plug is moveable by the knob to a plurality of positions to alter the gas conveyed to the rod.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority of U.S. Provisional Patent Application No. 61/633,639 filed on Feb. 14, 2012, entitled RIFLE LOWER AND UPPER RECEIVER AND MONOLITHIC HANDGUARD RAIL SYSTEM AND GAS PISTON SYSTEM AND IMPROVEMENTS, the entire contents of which are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to firearms and, more particularly, to gas recoil automatic and semiautomatic firearms and to improvements in the gas systems thereof. 
         [0003]    In firearms of the gas operated type in which propellant gases are tapped from the barrel and employed to drive a piston which actuates the gun action, it is often desirable to have some means of regulating the energy transmitted to the piston. This is especially desirable in firearms that are adapted to fire a variety of types of ammunition, each developing widely varying pressure characteristics in the barrel. 
         [0004]    If no control device is provided to compensate for the varying pressure, the gun must be designed to function with that round of ammunition which develops the least gas pressure energy on the operating piston. However, when firing rounds that develop high pressure levels, excessive energy is transmitted to the action which tends to increase wear and tear and shorten the life of the firearm. Current methods of compensating for the varying pressure suffer from one or more of the following deficiencies: inability to adjust for a wide range of ammunition, inability to quickly disassemble and clean the mechanism such as might be necessary in the field, require the release of light, heat and sound which may render the weapon unsuitable for certain uses and inefficiencies render the method unsuitable for use with certain types of ammunition, such as subsonic rounds. 
         [0005]    Accordingly, an improved system and method of controlling gas pressure in a piston actuated auto-loading firearm is needed. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the present invention is to integrate an improved gas piston operating system into a firearm that increases accuracy of the firearm while retaining an elegant and simple method of operation. Another object of the present invention is to provide an improved gas piston operating system that is simple to train users to operate. Another object of the present invention is to provide an improved gas piston operating system that extends the life expectancy of high-wear components. Another object of the present invention is to provide an improved gas piston operating system that has the ability to compensate for various ammunition types and for the use of various suppressors. 
         [0007]    In an embodiment, the present invention is directed to a gas system for a firearm having a barrel with a bore and a gas port in communication with the bore. The gas system has a gas block coupled to the barrel, the gas block having a gas capture port in communication with the barrel gas port. A pressure sleeve is removeably mounted inside the gas block, the pressure sleeve having a gas conduit in communication with the gas capture port; a seat proximal to the gas conduit; a projection; and a rod conduit for communicating gas through the projection. An operating rod is movably mounted in the gas block, the operating rod having a cup configured to fit over the projection. 
         [0008]    A valve is mountable to the gas block, the valve having a knob coupleable to the gas block; and a plug moveably mountable within the pressure sleeve, the plug having a plunger engageable with the seat to adjust gas flow through the gas conduit to the rod conduit. A spring is mounted around the rod for biasing the rod toward the gas block. Gas discharged from a fired cartridge flows through the gas port, the gas capture port, the gas conduit and the rod conduit and against the rod cup to drive the rod to reload the firearm. The plug is moveable by the knob to a plurality of positions to alter the gas conveyed to the operating rod. 
         [0009]    The operating rod may have a flange proximal to the cup and gas discharged from a fired cartridge may also flow against the flange to drive the rod to reload the firearm. The operating rod may also have at least one gas trap proximal to the flange and gas discharged from a fired cartridge may also flow into the gas trap to drive the rod to reload the firearm. The operating rod may have a plurality of gas traps. 
         [0010]    In an embodiment, the gas block has a sleeve for holding an end of the operating rod. The seat and the plunger may be substantially conical. The projection may be substantially cylindrical. In an embodiment, the gas system has a teardown pin, the pressure sleeve has a detent and the teardown pin is mountable in the detent to hold the pressure sleeve in the gas block. In an embodiment, the knob has a plurality of circumferential teeth and the gas block has a spring engageable with the teeth to maintain the position of the knob. Optionally, the knob is moveable to at least 20 different positions. In an embodiment, the plug further comprises at least one groove. The gas system may also have a barrel nut for coupling the barrel to a remainder of the firearm; and a heat sink coupled to the barrel nut, the heat sink having a rod guide. 
         [0011]    The present invention according to another embodiment is directed to a gas system for a firearm having a barrel with a bore and a gas port in communication with the bore, the gas system having a gas block coupled to the barrel, the gas block having a gas capture port in communication with the barrel gas port. A pressure sleeve is mountable inside the gas block, the pressure sleeve having: a gas conduit in communication with the gas capture port and a seat proximal to the gas conduit. An operating rod is movably mounted in the gas block over a portion of the pressure sleeve, the operating rod having a cup configured to receive gas from the gas conduit. A needle valve is mountable to the gas block, the valve having a plunger engageable with the seat to adjust gas flow through the gas conduit. Gas discharged from a fired cartridge flows through the gas port, the gas capture port and the gas conduit and against the cup to drive the operating rod to reload the firearm. 
         [0012]    The operating rod may also have a flange proximal to the cup and at least one gas trap proximal to the flange; and gas discharged from a fired cartridge may also flow against the flange and into the gas trap to drive the rod to reload the firearm. The seat and the plunger may be substantially conical. The gas system may also have a teardown pin and the pressure sleeve may have a detent; the teardown pin is mountable in the detent to hold the pressure sleeve in the gas block. 
         [0013]    The present invention is also directed to a firearm having a barrel with a bore and a gas port in communication with the bore. The firearm also has a gas system having a gas block coupled to the barrel, the gas block having a gas capture port in communication with the barrel gas port. A pressure sleeve is removeably mounted inside the gas block, the pressure sleeve having: a gas conduit in communication with the gas capture port; a seat proximal to the gas conduit; a projection; and a rod conduit for communicating gas through the projection. An operating rod is movably mounted in the gas block, the operating rod having a cup configured to fit over the projection; a flange proximal to the cup; and at least one gas trap proximal to the flange. 
         [0014]    A valve is mountable to the gas block, the valve having a knob mountable to the gas block; and a plug moveably mountable within the pressure sleeve, the plug having a plunger engageable with the seat to adjust gas flow through the gas conduit to the rod conduit. The firearm also has a means for biasing the rod toward the gas block. Gas discharged from a fired cartridge flows through the gas port, the gas capture port, the gas conduit and the rod conduit and against the rod cup, flange and trap to drive the rod to reload the firearm. The plug is moveable by the knob to a plurality of positions to alter the gas conveyed to the operating rod. In an embodiment, the seat and the plunger are substantially conical. In an embodiment, the gas block also has a means for maintaining position of the knob. In an embodiment, the firearm also has a barrel nut for coupling the barrel to the firearm and a heat sink coupled to the barrel nut, the heat sink having a rod guide. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying figures wherein: 
           [0016]      FIG. 1  is a perspective elevation view of a gas system of a firearm according to an embodiment of the present invention mounted to a barrel; 
           [0017]      FIG. 2  is an exploded view of the gas system of  FIG. 1 ; 
           [0018]      FIG. 3  is a side elevation cross sectional view of the gas system of  FIG. 1 ; 
           [0019]      FIGS. 4A and 4B  are perspective elevation views of a gas block usable in the gas system of  FIG. 1 ; 
           [0020]      FIG. 5  is a perspective elevation view of a pressure sleeve usable in the gas system of  FIG. 1 ; and 
           [0021]      FIG. 6  is a perspective elevation view of a valve plug usable in the gas system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    In the following description of the preferred embodiments, reference is made to the accompanying drawings which show by way of illustration specific embodiments in which the invention may be practiced. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. It is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the present invention. 
         [0023]      FIGS. 1 to 6  show a gas piston control system  10  for a firearm according to an embodiment of the present invention. The firearm has a cylindrical barrel  12  having a bore  14 . The barrel  12  is mounted to an upper receiver of the firearm using a barrel nut  18 . A heat sink  20  is mounted on the barrel nut  18  at a proximal end of the barrel  12 . A chamber in the upper receiver adjacent the proximal end of the barrel  12  is configured to receive a cartridge provided with a projectile. When the cartridge is fired, the projectile exits the barrel  12  at a distal end. 
         [0024]    The barrel  12  has a gas port  22  for communicating gas from the bore  14 . A gas block  24  is mounted to the barrel  12  proximate to the gas port  22 . An operating rod  26  is moveably mounted between the heat sink  20  and the gas block  24 . 
         [0025]    The gas block  24  has a clamp  28  that fits around the barrel  12 . The clamp  28  has a plurality of mounting holes  30 . At least one mounting bolt  32  fits through the mounting holes  30  to tighten the clamp  28  and affix the gas block  24  to the barrel  12 . In an embodiment, there are four mounting holes  30  and two mounting bolts  32 . In an embodiment, the mounting bolts  32  are quickly removable to allow for disassembly of the gas block  24  from the barrel  12 , such as for cleaning. 
         [0026]    As will be understood by those of skill in the art, other means for fastening the gas block onto the barrel may be used. For example, the barrel may have at least one mounting channel and the clamp may have mounting pins that pass through the mounting holes  30  and through the barrel mounting channel to affix the gas block  24  to the barrel  12 . Additionally, the barrel may have a transverse channel (not shown), the gas block may have a barrel alignment hole  31 . A pin  33  may be mountable through the barrel alignment hole  31  and the transverse channel on the barrel to ensure that the gas block is properly positioned on the barrel for mounting by the clamp. 
         [0027]    The components of the gas block  24  will now be considered in more detail with reference to  FIGS. 2 to 6 . The gas block  24  has a gas capture port  34  which is aligned with the barrel gas port  22  when the gas block  24  is mounted to the barrel  12 . The gas capture port  34  allows for gas from the bore  14  to be communicated inside the gas block  24 . The gas block  24  has an operating rod sleeve  36  for holding an end of the operating rod  26 . 
         [0028]    A pressure sleeve  38  is removably positioned in the gas block  24 . The pressure sleeve  38  has a gas conduit  40  that aligns with the gas capture port  34  for communication of gas from the barrel  12 . The pressure sleeve also has a rod conduit  42  that passes through a substantially cylindrically shaped projection  43  for communication of gas to the operating rod  26 . Between the gas conduit  40  and the rod conduit  42  is a seat  44 . In an embodiment, the seat  44  is substantially conical. 
         [0029]    The pressure sleeve  38  has a lock detent  46  for engagement with a teardown lock  48  on the gas block  24 . In an embodiment, the teardown lock  48  has a spring  50  and a pin  52 . The spring  50  holds the pin  52  in the detent  46  until the pin  52  is manually disengaged from the detent  46  to allow for removal of the pressure sleeve  38  such as for cleaning. Additionally, the pressure sleeve has an alignment tab  54  engageable with an alignment detent  56  in the gas block  24  to allow a user to easily align the pressure sleeve  38  within the gas block  24 . 
         [0030]    The gas piston control system also has an adjustable valve  58 . The valve  58  has a knob  60  coupled to a plug  62 . The knob  60  threads onto the gas block  24  to adjustably position the valve plug  62  within the pressure sleeve  38 . By turning the valve knob  60 , the valve plug  62  is infinitely adjustable between a position completely blocking the pressure sleeve gas conduit  40  and a position completely opening the pressure sleeve gas conduit  40 . 
         [0031]    With reference to  FIG. 6 , the valve plug  62  has a shank  64  proximal to the adjuster valve knob  60 , a body  66  and a plunger  68 . The plunger  68  is configured to correspond to the seat  44  such that the plunger  68  may form a substantially leak free seal with the seat  44 . In an embodiment, the plunger  68  is substantially conically shaped. In an embodiment, the body  66  further comprises at least one groove  69  to create a seal reducing the amount of gas that can escape around the plug  62 . 
         [0032]    In an embodiment, an outer circumference of knob  60  has a plurality of teeth  70 . A spring  72  is coupled to the gas block  24  and engages the teeth  70  to limit unintentional rotation of the knob  60  and hold the valve plug  62  in a given position. The knob  60  contains a plug hole  74  through which the shank  64  is fitted. The knob  60  is coupled to the shank  64  using a fastener  76  such as a pin or c-clip. The number of teeth and the threads may be used to control how many different positions the valve plug may have between a fully open and a fully closed position. Preferably, the knob may be moved to at least 10 different positions, even more preferably to at least 20 different positions and even more preferably to at least 40 positions to allow for precise control over highly variable ammunition and suppressors. 
         [0033]    The operating rod  26  will now be considered in more detail with reference to  FIGS. 2 and 3 . A first end of the operating rod  26  is positioned in the operating rod sleeve  36  of the gas block  24 . Proximal to the first end of the operating rod  26  is a cup  80  for receiving gas. The cup  80  fits over the projection  43  of the pressure sleeve  38 . The operating rod also has a flange  82  and at least one gas trap  84 . The cup  80 , flange  82  and gas trap  84  allows for a very efficient three stage system for activating the operating rod  26  using gas from the bore  14 . Gas is initially fired into the cup  80 . Gas is then incident on flange  82  while the operating rod  26  is fitted in pressure sleeve  38 . Finally, pressure from gas leaving the pressure sleeve  38  is picked up the at least one gas trap  84 . The operating rod  26  also has a flange  86  for mounting a spring as discussed below. 
         [0034]    A second end of the operating rod  26  is positioned in an operating rod guide  88  on the heat sink  20 . The operating rod guide  88  helps keep the operating rod  26  properly aligned. A spring  90  is mounted between the heat sink  20  and the flange  86 . The spring  90  provides force on the operating rod  26  to maintain a secure fit against the pressure sleeve  38 . The operating rod  26  is actuated by the force of expanding gas following the projectile through the barrel  12 . The gas travels through the barrel gas port  22 , the gas block gas capture port  34  and the pressure sleeve gas conduit  40  and the pressure sleeve rod conduit  42 . The gas then acts on the cup  80 , flange  82  and gas trap  84  of the operating rod  26  to turn pneumatic force into mechanical force and push the operating rod toward the upper receiver. The operating rod  26  drives a carrier in the upper receiver to cause a spent cartridge to be ejected and a new cartridge to be chambered. After the operating rod  26  strikes the carrier, the spring  90  forces the operating rod  26  back against the pressure sleeve  38 . 
         [0035]    The barrel nut  18  and heat sink  20  attach the barrel to the upper receiver of the rifle system, are a rigid attachment point for a hand guard and align the operating rod  26  through the upper receiver. Preferably, the barrel nut  18  and heat sink  20  are made from a highly conductive material to transfer heat from the barrel  12  into the hand guard to allow for faster cooling of the barrel  12 . In an embodiment, at least one of the barrel nut  20  and the heat sink  20  are made of aluminum. 
         [0036]    The system of the present invention provides increased consistency because the time the driving gas is in the system is reduced, which limits the time and area in which the gas can condense. This makes use of the pneumatic gas energy faster, thereby allowing for a shorter cycle time. Additionally, a substantially conically shaped seat  44  and plug  62  allows a large surface to be exposed to the hot gases which reduces the wear on the seat  44  and the plug  62 . Gas pressure is regulated by rotating the knob  60  to move the plug  62  and the plunger  68  in relation to the seat  44  to progressively open or close the pressure sleeve gas conduit  40 . This allows for adjustment of gas pressure to control carrier speed for different types of ammunition, as well as for suppressed fire or different rates of automatic fire. 
         [0037]    The gas system according to embodiments of the present invention is intended to be used with firearms having a barrel with a bore and a gas port communicating gas from the bore, such as for example an AR-15 or M16 rifle. Preferably, the upper receiver is designed with a heavier mass than typical upper receivers to compensate for the increased force and torque involved with the gas piston system. The extra mass also allows for more consistent thermal behaviors, including the ability to absorb more heat out of the gas piston system. 
         [0038]    The system of the present invention is designed to direct gas directly from the barrel onto the rod. This system is much more efficient than systems that require a chamber in a gas block to become pressurized and allows for the use of more varied ammunition. A firearm utilizing the gas system of the present invention may be used in a fully automatic mode with subsonic ammunition and with noise suppression, such as for use in tactical situations where noise suppression is critical. 
         [0039]    The pressure sleeve  38  and operating rod  26  may be easily removed for cleaning, modification or replacement. The valve plug  62  may be removed from the gas block  24  by unscrewing the knob  60  until the knob threads disengage from threads on the gas block. The valve plug  62  may then be pulled out of the pressure sleeve  38  and the gas block  24 . Once the valve plug  62  has been removed, the pressure sleeve  38  may be removed by manually disengaging the pin  52  from the detent  46  in the pressure sleeve. Once the pressure sleeve  38  has been removed the operating rod  26  may be removed by sliding the operating rod out through the gas block  24 . This entire operation may be done very quickly and without tools, such as by a soldier in the field. 
         [0040]    There is disclosed in the above description and the drawings, a gas system for a firearm which fully and effectively overcomes the disadvantages associated with the prior art. However, it will be apparent that variations and modifications of the disclosed embodiments may be made without departing from the principles of the invention. The presentation of the preferred embodiments herein is offered by way of example only and not limitation, with a true scope and spirit of the invention being indicated by the following claims. 
         [0041]    Any element in a claim that does not explicitly state “means” for performing a specified function or “step” for performing a specified function, should not be interpreted as a “means” or “step” clause as specified in 35 U.S.C. §112.