Patent Publication Number: US-6662797-B1

Title: Transparent gun elements

Description:
FIELD OF THE INVENTION 
     The present invention relates to guns, including guns for use in the sport of paintball. 
     BACKGROUND OF THE INVENTION 
     Conventional firearms have a firing mechanism to fire a projectile and a barrel to direct the projectile in a desired direction. Guns are made for numerous purposes and include many designs, for example, rifles, shot guns, and hand guns. Guns are designed to use many different mechanisms for firing a projectile. For example, one type of gun is dependant on having a propellant combined with the projectile. In this type of gun, the firing mechanism detonates the propellant contained in the projectile, which launches the projectile along the barrel. This type includes shot guns, which fire cartridges comprised of shot packaged with explosive material, and conventional rifles, machine guns, and handguns, which shoot bullets comprised of a unitary slug packaged with explosive material in a casing. 
     Another method of firing a projectile uses a propulsion source separate from the projectile, such as compressed gas, including air, carbon dioxide, nitrogen, and others. Examples of such guns include, air riffles, BB guns, and paintball guns or “markers.” These guns either include a pump for compressing ambient air or are adapted to receive compressed air from a source, such as a compressed gas cartridge or gas cylinder. Conventional paintball guns rely on such cartridges or gas cylinders for supplying compressed gas, including air, nitrogen and carbon dioxide. 
     The introduction of debris into the firing mechanism or barrel of any firearm can affect the ability of the firearm to fire a projectile and affect the accuracy of the shot. For example, debris can jam the firing mechanism or debris can deflect or obstruct the path of a projectile within the barrel. 
     In the case of paintball guns, the projectile is a paintball, which is a volume of paint encased in a spherical shell comprised of a breakable casing. The paintball is designed to explode upon impact against an intended target, but occasionally paintballs inadvertently break prematurely prior to impact, and can even burst while loading or firing within the paintball gun. Paint residue from an exploded paintball remaining inside the paintball gun typically inhibits the trajectory and speed of later-fired paintballs and can even jam the paintball gun. If a paintball gun is able to continue firing after an inadvertent paintball bursts within the paintball gun, it is not always immediately apparent that paint residue resides in the paintball gun. The failure to realize that paint residue remains within the paintgun including the paintgun barrel, can result in misfired or misdirected shots until the residue is removed from the paintgun. 
     As a propellant, conventional paintguns employ compressed gas, which often remains in a partially liquid state, for example, in the case of carbon dioxide. In many paintball guns, a gas cylinder is attached to the gun in a substantially horizontal position. In this position, liquid compressed gas can flow into the gun&#39;s firing mechanism. Even when the compressed gas cylinder is not configured in a horizontal position with respect to the paintball gun, liquified gas can inadvertently enter the firing mechanism during game play when the paintball gun is being carried in various positions. Because compressed gas in a liquid state occupies a smaller volume than when it is in a gas state, the entry of liquified gas into the firing mechanism (known as “going liquid”) can have the undesired effect of allowing too much gas into the gun&#39;s expansion chamber, resulting in a gun that fires under excessive pressure, sometimes referred to as a “hot” gun. A hot gun is more likely to prematurely rupture a paintball and can also injure a participant who is hit with a paintball traveling at excessive speed. 
     One method used to inhibit the entry of liquified gas into the firing mechanism of a paintball gun is to provide an expansion chamber in communication between the compressed gas source and the firing mechanism. Such an expansion chamber provides a volume within which liquified gas can evaporate prior to entering the paintball gun, particularly the firing mechanism. Commonly, such expansion chambers are equipped with a plurality of baffles to further inhibit the passage of liquified gas into the firing mechanism. Even with a gun suited with an expansion chamber, liquified gas can enter the firing mechanism of a paintball gun. For example, during game play, the paintball gun may be held in a downward position with the expansion chamber below the gas cylinder, allowing gravity to fill the expansion chamber with liquified gas. Accordingly, it is desirable to ascertain whether liquid occupies the expansion chamber before firing the paintball gun. 
     The present invention solves the foregoing and other problems in the art and satisfies the industry demands. 
     SUMMARY OF INVENTION 
     It is an object of the invention to provide a barrel for a gun having a portion comprising a substantially transparent material. The barrel can be made of any substantially transparent material, but in one embodiment the material is a polycarbonate. Other suitable materials for the barrel include glass, such as tempered glass. 
     In another aspect of the invention, the barrel is coated with a substantially transparent material to add hardness, which provides scratch resistance, and prevents deterioration of the polycarbinate from the absorption of dyes from paintballs and solvents used to clean the gun. 
     In another aspect of the invention, a barrel assembly is constructed by attaching the barrel to a barrel cage comprised of a stiff material, for example, metal such as aluminum. The barrel cage provides protection to the barrel and also creates a desirable appearance. 
     In another aspect of the invention, an expansion chamber is provided having a housing with a portion comprising a substantially transparent material. The expansion chamber is comprised of a base, a cover, and a housing between the base and the cover. The expansion chamber includes an inlet for accepting compressed gas and an outlet for discharging compressed gas. 
     In another aspect of the invention, the expansion chamber housing is comprised of a polycarbonate. In another aspect of the invention, the housing is comprised of glass, specifically, tempered glass. In yet a further aspect of the invention, the housing is coated with a substantially transparent material to reduce scratching and absorption of pressurized gas into the transparent material. 
     In another aspect of the invention, the housing is partially enclosed within a cage to provide additional burst protection and stiffness to the expansion chamber. 
     In another aspect of the invention, a plurality of baffles is disposed within the housing. 
     The foregoing features and advantages of the present invention will be apparent from the following more detailed description of the invention. Other features and advantages of the invention will be apparent from the following detailed description and accompanying figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a prospective view of a paintball gun equipped with a barrel assembly and expansion chamber of the present invention; 
     FIG. 2 is a cross sectional view of the barrel assembly of the embodiment shown in FIG. 1; 
     FIG. 3 is a plan view of the barrel assembly of the embodiment shown in FIG. 1; 
     FIG. 4 is a plan view of the barrel of the embodiment shown in FIG. 1; 
     FIG. 5 is a plan view of the barrel of the embodiment shown in FIG. 1; 
     FIG. 6 is a cross sectional view of the barrel of the embodiment shown in FIG. 5; 
     FIG. 7 is a plan view of the cage of the embodiment shown in FIG. 1; 
     FIG. 8 is a cross sectional view of the cage of the embodiment shown in FIG. 7; 
     FIG. 9 is a plan view of the muzzle of the embodiment shown in FIG. 1; 
     FIG. 9 a  is a cross sectional view of the muzzle of the embodiment shown in FIG. 9; 
     FIG. 9 b  is a end view of the muzzle of the embodiment shown in FIG. 9; 
     FIG. 10 is a cross sectional view along the line A—A of the muzzle of the embodiment shown in FIG. 9; 
     FIG. 11 is a cross sectional view along the line B—B of the muzzle of the embodiment shown in FIG. 9; 
     FIG. 12 is a plan view of the expansion chamber of the embodiment shown in FIG. 1; 
     FIG. 13 is a cross sectional view of the expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 14 is a side view of the base of the expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 15 is a cross sectional view of the base of the expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 16 is a top view of the base of the expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 16 a  is a cross sectional view of the baffle assembly of the expansion chamber of the embodiment shown in FIG. 13; 
     FIG. 17 is a plan view of the baffle assembly of the expansion chamber of the embodiment shown in FIG. 13; 
     FIG. 18 is a cross sectional view along line C—C of the baffle assembly of the expansion chamber of the embodiment shown in FIG. 13; 
     FIG. 19 is a plan view of the cover of the expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 20 is a cross sectional view along line A—A of the expansion chamber of the embodiment shown in FIG. 19; 
     FIG. 21 is a plan view of the cage of the expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 22 is a cross sectional view along line A—A of the cage of the expansion chamber of the embodiment shown in FIG. 21; 
     FIG. 23 is a plan view of the housing of expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 24 is an end view of the housing of expansion chamber of the embodiment shown in FIG. 12; 
     FIG. 25 is a top view of the bolt of expansion chamber of the embodiment shown in FIG. 13; 
     FIG. 26 is a plan view of the bolt of expansion chamber of the embodiment shown in FIG.  25 ; 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIG. 1, gun  1  includes a barrel  5  having a portion  6  comprising a substantially transparent material. As shown in FIG. 2, the barrel  5  (also referred to as member  5 ) defines an axial bore  7 , which is attached to a gun housing  2  containing a firing mechanism (not shown) for directing a projectile (not shown) along the axial bore  7 . The barrel  5  can be made of any substantially transparent material, such that the material allows the inside of the barrel  5  to be visible to the extent that debris, for example, paint, can be seen through the barrel  5 . Accordingly, a translucent material would also be substantially transparent. In one embodiment the material is a polycarbonate. Polycarbonate has desirable attributes in that it is relatively strong and stiff, thus resisting bending, crushing or other deformation of the barrel  5  that could impede or distort the trajectory of a projectile, diminishing accuracy of the gun  1 . Other suitable materials for the barrel  5  include other polymers and glass. In the case of glass, it is desirable to use tempered glass, which is more durable and less prone to shattering when broken. 
     Certain materials, such as polycarbinate, are prone to scratching and/or absorption of paints and dyes. It has been found desirable to coat such materials with a substantially transparent material to reduce these undesirable effects. Silicon has been found to add hardness, which provides scratch resistance, and prevents deterioration of the polycarbinate from the absorption of dyes from paintballs and solvents used to clean the gun. When using tempered glass, the addition of a transparent coating such as a transparent or translucent polymer, including polyurethane, helps prevent the glass from shattering and breaking into shards. 
     As shown in FIGS. 2 and 3, in one embodiment, a barrel assembly  10  can be constructed by attaching the barrel  5  to a cage  8 . The cage  8  is comprised of a stiff material, for example metal such as aluminum. The barrel cage  8  provides protection to the barrel  5  and also creates a desirable appearance. For example, the cage  8  prevents bending, warping or crushing of the barrel  5 . The cage  8  can be formed as a solid cylinder or any number of patterns may be cut in to the cage  8  to provide a desirable appearance and allow the user to view the interior of the barrel  5 . 
     Many paintguns are adapted to allow barrel assembly  10  to be removably attached to the paintgun for cleaning, storage, shipping. In addition, after-market barrel assemblies allows users to select from various models of barrel assemblies. Conventional barrel assemblies are removably attachable by threading the barrel assembly into the gun housing. While the cage  8  is not necessary to practice the present invention, the cage  8  provides an additional advantage of being more readily removably attachable to a paintgun  1 . In particular, the barrel  5  of the present invention may be directly attached to the gun housing  2 , for example, by threads, adhesive, press-fitting or other methods known in the art, but by attaching the barrel  5  to the cage  8 , the barrel assembly  10  provides additional durability. Constructing the cage  8  from metal, such as aluminum, rather than polycarbonate or glass, provides added strength and allows the barrel assembly  10  to be more frequently detached and attached to the paintgun  1 . 
     In one method of construction of the barrel assembly  10 , if the barrel  5  is comprised of a polycarbonate, a temperature differential can be created between the barrel  5  and the cage  8 , shrinking the barrel  5  relative to the cage  8  (or expanding the cage  8  relative to the barrel  5 ), due to the different expansion properties of the respective materials of the barrel  5  and cage  8 . Thus, the tolerance between the barrel  5  and cage  8  can be reduced, and when the temperature of both components equalize, a tight fit is created. In addition or alternatively, the barrel  5  and/or cage  8  can be adapted to define a groove  9  or cavity for receiving an adhesive. The adhesive may applied before attaching the barrel  5  to the cage  8  or the cage  8  can be adapted to contain one or more aperture  11  to accept an injection of adhesive into the groove  9 . Of course many alternative methods of construction, as known to those of ordinary skill in the art, could be used to attach the barrel  5  to the cage  8 , for example, threading the respective components. 
     In addition, the barrel assembly  10  can be fitted with a muzzle  15 . In one embodiment, the muzzle  15  is comprised of aluminum, although the muzzle  15  can be constructed of any material. The muzzle  15  is formed with slots  16  or openings, which are believed to allow the escape of ambient air residing in front of a projectile in the barrel  5  immediately after a projectile is fired. The slots  16  are also believed to reduce the noise from a fired shot. The muzzle  15  may be attached to the barrel  5  by the same methods described above for attaching the barrel  5  to the cage  8 . 
     As shown in FIG. 1, a gun  1  can be comprised having a mechanism for firing a projectile (not shown) and a barrel assembly  10  attaching to the firing mechanism for directing the projectile. The barrel assembly  10  has a portion  6  comprising a substantially transparent material. The barrel assembly  10  is comprised of a barrel  5  attached to a cage  8  and a muzzle  15 . 
     FIGS. 12 and 13 disclose an expansion chamber  20  for a compressed-gas-powered gun  1 . The expansion chamber  20  is comprised of a base  22 , a cover  23 , and a housing  25  between the base  22  and the cover  23 . The expansion chamber  20  includes an inlet  26 , shown in FIGS. 14 and 15, for accepting compressed gas and an outlet  27 , shown in FIG. 13, for discharging compressed gas. The inlet  26  is proximate to the base  22  and the outlet  27  is proximate to the cover  23 . 
     The housing  25  has a portion comprising a substantially transparent material. In one embodiment, the housing  25  is comprised of a polycarbonate. In another embodiment, the housing  25  is comprised of glass, specifically, tempered glass. As discussed above, it is desirable to coat such materials with a substantially transparent material to reduce scratching. In addition, under severe pressure, as exists in a typical paintgun application, certain transparent materials, such as polycarbonate, absorb certain gases, such as carbon dioxide. Absorption of pressurized gas into the transparent material can have the further undesired effect of clouding the material, reducing the transparency of the material and detracting from the aesthetic appeal of the material. Silicon has been found to add hardness, which provides scratch resistance, and prevent absorption of dyes compressed gasses such as carbon dioxide. In addition, upon actuating a paintgun  1  with a compressed gas source, the expansion chamber  20  is under great pressure from the compressed gas. A transparent coating such as a polymer helps prevent the transparent material, such as glass, from cracking, shattering or breaking into shards, and creating a safety hazard. 
     As shown in FIG. 12, the housing  20  is partially enclosed within a cage  30 , to provide additional protection and stiffness to the expansion chamber  20 . 
     As shown in FIGS. 13 and 16, one embodiment includes a plurality of baffles  33   a ,  33   b ,  33   c ,  33   d  disposed within the housing  27 . The baffles  33   a ,  33   b ,  33   c ,  33   d  impede the entry of liquified gas from flowing towards the outlet  27 . In one embodiment, the baffle assembly  35  comprises a plurality of baffles  33   a ,  33   b ,  33   c ,  33   d  attached to column  36 . While the present embodiment discloses baffle assembly  35  comprised of a unitary component, the baffle assembly  35  could be formed of multiple components, without departing from the invention. Further, there are numerous styles and combinations of baffle assemblies known to those of skill in the art, which could be substituted for the one disclosed herein without departing from the invention. 
     The expansion chamber  20  is constructed as follows. The base  22  has an axial bore  24  through the base  22  for constructing the expansion chamber  20 . A bore  28  is provided in the base  22 , in communication with a second bore  29 , which together act as an inlet  26  for compressed gas. The axial bore  24  in the base  22  is adapted to receive the first end  31  of the baffle assembly  35 , which is secured to the base  22  by bolt  38 . Bolt  38  is adapted to receive a sealing member  39  comprising an O-ring. The housing  25  is comprised of a cylindrical section, which is adapted to be received by an annular groove  21  in base  22 . Base  22  is adapted to retain sealing member  41  comprising an O-ring to create a seal between the base  22  and the housing  25 . Cage  45  slips over housing  25  and rests against base  22 . Cage  45  provides additional support for the housing  25  to prevent undue expansion and possible bursting of the housing  25 . 
     The second end  32  of baffle assembly  35  is provided with external threads  34  and an axial bore  36 . Cover  23  has an axial bore  37 , which acts as the outlet  27  for expansion chamber  20 . Axial bore  37  further contains internal threads  42  that mate with external threads  34  of baffle assembly  35  and an annular groove  43  to receive housing  20 . When baffle assembly  35  is mated to cover  23 , the housing  25  and cage  30  are maintained between the base  22  and cover  23 . O-ring sealing member  44  is secured between baffle assembly  35 , cover  23  and housing  25 , sealing all three components. O-ring sealing member  46  is disposed between baffle assembly  35  and cover  23 , sealing the components. Cover  23  is further provided with external threads  47  to attach the expansion chamber  20  to the gun  1  and a groove  48  to support sealing member (not shown) for sealing the connection between the expansion chamber  20  and the gun  1 . Sealing members  49   a ,  49   b ,  49   c  provide a seal between baffles  33   a ,  33   b ,  33   c  and housing  25  to force the fluid flow as described next. 
     In operation, fluid flows through expansion chamber  20  as follows, although innumerable baffle configurations (or no baffles) could be created without departing from the present invention. Fluid enters expansion chamber  20  through inlet  26  in base  22 . Fluid continues through cross bore  51 , axial bore  52  and exits baffle assembly  35  through cross bore  53 . Fluid continues through notches  54   a ,  54   b  in baffles  33   b ,  33   c . Finally, fluid flows through cross bore  55  and axial bore  36  in baffle assembly  35 , exiting through outlet  27  of the expansion chamber  20 . 
     As shown in FIG. 1, a pneumatic gun comprises a gun housing  2  containing a firing mechanism (not shown) for firing a projectile. The firing mechanism is powered by a volume of compressed gas supplied from a compressed gas source (not shown). The compressed gas source (not shown) attaches to an air source adapter  60 , which is in communication with linkage  62 . Linkage  62  is attached to inlet  26  of expansion chamber  20 . Expansion chamber  20  is attached to gun housing  2 . Gun housing  2  attaches to barrel assembly  10 . 
     While the invention has been particularly shown and described with reference to a particular embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. The present example and embodiment, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.