Abstract:
The invention is a pin valve having a detachable valve body cover which makes the valve stem assembly accessible from the end of the valve in which the valve stem protrudes. The removable valve body cover can be replaced independently if this end of the valve is damaged. The valve body cover also has a valve seat which is more accessible and is more easily machined. The valve body cover is typically adapted to accommodate an allen wrench type tool to simplify removal and reattachment. The invention eliminates the need to disconnect the valve at the second open end when replacing the valve stem assembly.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to valves, and, more specifically to pin valves. 
     BACKGROUND OF THE INVENTION 
     Pin valves have been in existence for a quite some time and have been used for a multiplicity of purposes. Within the last 15 to 20 years pin valves have been adapted to be used in gas powered guns suitable for projecting paint balls. These type of guns have become popular for use in simulated combat games. Pin valves are an important component of these guns because they provide a removable connection between the gun and a high pressure gas source such as a CO 2  tank. The pin valve enables the CO 2  tank to be easily detached from the gun when the gun is not in use or when the CO 2  tank requires recharging. 
     As shown in FIG. 1, a prior art pin valve typically comprises a substantially cylindrical valve body having a first open end, a second open end, and an internal valve chamber in flow through connection with the first open end and the second open end. In a typical application, the first open end of the valve is connected to a paint ball gun, while the second open end is connected to a CO 2  tank. A valve stem assembly is disposed within the internal valve chamber. The valve stem assembly in a prior art pin valve may be accessed and removed only through an access opening in the second open end of the valve body. The valve stem protrudes through a valve stem opening in the first open end of the valve body. The valve stem moves between a retracted position where the valve is open and an extended position where the valve is closed. The valve stem is biased toward the extended position such that the valve stem protrudes through the valve stem opening in the valve body and a O-ring seal surrounding the valve stem is in sealing contact with a valve seat located on the inner surface of the internal valve chamber proximal to the first open end of the valve body. The pin valve is opened when the valve stem is depressed and moved to the retracted position such as by being connected to a paint ball gun at the first open end of the pin valve. 
     The first open end of the pin valve is typically disconnected from the paint ball gun when the gun is not in use. The valve stem is in the extended position and the valve is closed when the first open end is disconnected. Unfortunately, when the first open end of the pin valve is disconnected from the paint ball gun it becomes exposed and is easily dented or otherwise damaged. If the first open end of the valve is dented, for example by hitting a solid object such as a concrete curb or a truck bed wall, it can result in damage to the valve stem or the inability to form an air-tight seal at this perimeter of the valve. The result is a pin valve that leaks. 
     Also, valve stems sometimes leak because of a poor seal between the O-ring and the valve seat. This problem frequently arises because of the difficulty in forming a proper valve seat surface during the manufacture of prior art pin valves. In order to have a valve that does not leak, it is vital that the surface of the valve seat is machined properly so that the valve seat has a sufficiently smooth and contiguous surface. Unfortunately, the valve seat surface is difficult to access in a prior art pin valve because it is disposed within the internal valve chamber at the opposite end of the cylindrical valve body from the access opening. The result is that many valve seat surfaces are imprecisely machined and a undue number of new valves need to be discarded prematurely because they leak. 
     A problem with prior art valves is that they are not amenable to being repaired. In fact, the valves currently used in paint ball guns are one of the most commonly replaced parts of the paint ball gun because they are not easily repaired. A particular problem is that replacement of the valve stem is difficult and time consuming. As shown in the prior art valve in FIG. 1, the valve stem assembly must be removed and replaced from the access opening in the second open end of the valve body. This requires that the entire valve be disconnected from the CO 2  tank. Disconnecting the second open end of the valve is difficult because the threaded connection is typically fixed to the CO 2  tank by the application of a special sealant material. The sealant acts to physically secure the connection between the valve and the CO 2  tank and to prevent leaks at this junction. This sealant can be difficult to properly apply, and is even more difficult to remove when disconnecting the valve. Breaking this seal usually requires that the connection between the valve and the CO 2  tank be heated to loosen the previously applied sealant. When a valve is reconnected it is important that the sealant material be properly applied because the connection may otherwise leak or pose a safety hazard. However, the sealant material may not be readily available when the valve needs to be replaced. Moreover, application of the sealant material entails a requisite level of skill not possessed by many persons owning or servicing the gun. Improper application of the sealant material, or failure to use the sealant material, can result in a safety hazard because the back end of the valve may become unscrewed when disconnecting the first end of the valve. 
     A further problem with prior art valves is that damage to the face of the first end typically requires that the entire valve be replaced. As shown in the prior art valve illustrated in FIG. 1, the face of the first end where the valve stem protrudes is integral with the first end of the valve body. When this face is dented the valve must often be replaced in its entirety rather than being repaired because the face is integral with the valve body. Needless to say, replacement of the entire pin valve is this is not a cost effective approach to maintaining the valve in proper working condition. 
     There is therefore a need for a valve which is easier to manufacture, easier to repair, and allows the valve stem assembly to be replaced directly from the first open end of the valve body. 
     SUMMARY 
     The invention satisfies this need. The invention is an improved valve which is more easily repaired, and which is suitable for being used in a gas propelled paint ball gun for connecting the gun to a pressurized gas source. 
     The invention comprises: 
     (a) a valve body having first and second open ends; 
     (b) a valve body cover reversibly attached to the first end of the valve body, the valve body and the valve body cover cooperating to define an internal valve chamber, the valve body cover having an external face, an internal face and a valve stem opening, the internal face of the valve body cover comprising a valve seat; and 
     (c) a valve stem assembly disposed within the valve chamber, the valve stem assembly comprising a valve stem body, a valve stem attached to the valve stem body and a valve stem seal, the valve stem being movable between a retracted valve stem position and an extended valve stem position and being biased toward the extended valve stem position, the valve stem assembly being disposed within the valve chamber such that, (i) when the valve stem is in the extended valve stem position, the valve stem protrudes through the valve stem opening in the valve body cover and the valve stem seal is in sealing contact with the valve seat so as to seal closed the valve stem opening, and (ii) when the valve stem is in the retracted valve stem position, the valve stem seal is spaced apart from the valve seat sufficient so that the valve stem opening is not sealed closed. 
     The detachable valve body cover at the first open end of the valve body enables the valve stem assembly to be replaced directly from the first open end of the valve body, and thus virtually eliminates the need to disconnect the valve at the second open end. The valve seat surface is readily machined to form a smooth surface because it is disposed on the inner surface of the separately machined valve body cover. In a preferred embodiment, the removable valve body cover protects the first open end of the valve body and can be replaced independently if damaged. The removal of the valve body cover is simplified by designing the external face of the valve body cover such that it accommodates an allen wrench type tool. 
    
    
     DRAWINGS 
     These features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying figures where: 
     FIG. 1 is cross-sectional view of a prior art pin valve; 
     FIG. 2 is a cross-sectional view of a first embodiment having features of the invention; 
     FIG. 3 is a cross-sectional view of a second embodiment having features of the invention; and 
     FIG. 4 is a side view of a combination having features of the invention. 
    
    
     DETAILED DESCRIPTION 
     The following discussion describes in detail two embodiments of the invention and several variations of those embodiments. This discussion should not be construed, however, as limiting the invention to those particular embodiments. Practitioners skilled in the art will recognize numerous other embodiments as well. For example, the valves described herein are not limited to being used in gas propelled paint ball guns and may be used in connection with other equipment and devices. 
     The invention is a pin valve  10  comprising a valve body  12 , a valve body cover  14 , and a valve stem assembly  16 . 
     The valve body  12  is substantially cylindrical and comprises a first open end  18  which is in flow through contact with a second open end  20 . The valve body  12  and the valve body cover  14  cooperate to define an internal valve chamber  22  that is disposed within the valve body  12 . The internal valve chamber  22  is typically cylindrical. As illustrated in the embodiments in drawings, the valve body  12  preferably comprises external threads  24  proximal to the first open end  18  and proximal to the second open end  20  to enable the pin valve  10  to be connected to appropriate connectors at each end of the valve body  12 . In the embodiments illustrated in drawings, the valve body  12  further comprises a recessed lip  26  at the radial perimeter of the valve body  12  at the first open end  18  which accommodates a first open end O-ring  28 . The first open end O-ring  28  is sized and dimensioned such that it protrudes slightly from the radial perimeter of the valve body  12  and facilitates the formation of an air tight seal between the first open end  18  and an appropriate connector. In a typical embodiment, the diameter of the valve body  12  is between about ½ inches and about 1 inches and the length of the valve body  12  along it&#39;s longitudinal axis is between about 1 inches and about 3 inches. 
     The valve body cover  14  is attached to the first open end  18  of the valve body  12  and comprises an external face  30 , an internal face  32 , and a valve stem opening  34 . Preferably, the valve body cover  14  reversibly attaches to the valve body  12 , such as by a threaded connection. As illustrated in the embodiments in the drawings, the valve body cover  14  comprises external valve body cover threads  36  disposed between the external face  30  and the internal face  32 . In these embodiments, the internal valve chamber  22  further comprises chamber threads  38  that accommodate the valve body cover threads  36 . 
     The external face  30  of the valve body cover  14  typically comprises a valve body cover orifice  40  which is sized and dimensioned to accommodate an allen wrench tool. As used herein, the form of an allen wrench tool is meant to be interpreted broadly to include all tools which are suitable for applying torque to attach and detach the threaded valve body cover  14 , including, for example, screwdrivers. A typical allen wrench tool is an L-shaped tool with at least one end terminating in a bit having the cross section shape of a hexagon, pentagon, octagon, or square. 
     In the embodiment illustrated in FIG. 2, the external face  30  of the valve body cover  14  comprises a flange  42  that substantially covers the first open end  18  of the valve body  12 . Typically, the flange  42  is circular and is sized and dimensioned to substantially cover the first open end  18  of the valve body  12 . Typically, the thickness of the flange  42  is between about 0.030 inches and about 0.070 inches. In the embodiment illustrated in FIG. 2, the first open end O-ring  28  is disposed between the flange  42  of i the valve body cover  14  and the recessed lip  26  of the valve body  12 . The embodiment in FIG. 2 is distinguishable from the embodiment illustrated in FIG. 3, in which the external face  30  of the valve body cover  14  does not comprise a flange  42 . 
     The valve stem assembly  16  is disposed within the internal valve chamber  22 . The valve stem assembly  16  comprises a valve stem body  44  and a valve stem  46  that is attached to the valve stem body  44 . The valve stem  46  is capable of moving back and forth between a retracted valve stem position and an extended valve stem position. The valve stem  46  is biased toward the extended valve stem position. As illustrated in the embodiments in the drawings, the valve stem  46  is preferably fixedly attached to the valve stem body  44 . In these embodiments, there is a spring  48  disposed within the internal valve chamber  22  proximal to the second open end  20  of the valve body  12 . The spring  48  places a biasing force upon the valve stem body  44  and valve stem  46  directed toward the valve stem opening  34 . It is the force from this spring  48  which biases the valve stem  46  toward the extended valve stem position. 
     In an alternative embodiment, the valve stem assembly  16  comprises a stationary valve stem body  44  and a movable valve stem  46  that is attached to the valve stem body  44 . Again, the valve stem  46  is capable of moving back and forth between a retracted valve stem position and an extended valve stem position. In this embodiment this is accomplished by placement of a spring within the valve stem body  44  that interacts with the valve stem  46  and places a force directed toward the valve stem opening  34  upon the valve stem  46 . As the valve stem  46  is retracted, the portion of the valve stem  46  proximal to the stationary valve stem body  44  enters the valve stem body  44 . 
     The valve stem assembly  16  further comprises a valve stem seal  50 . As illustrated in the embodiments in the drawings, the valve stem seal  50  is preferably disposed radially about the valve stem  46  within the internal valve chamber  22 . The internal face  32  of the valve body cover  14  further comprises a valve seat  52 . The valve seat  52  is disposed within the internal valve chamber  22  on the internal face  32  of the valve body cover  14 . As illustrated in the embodiments in drawings, the valve seat  52  is preferably radially disposed around the valve stem opening  34  such that it encircles the valve stem opening. In these embodiments, the valve stem seal  50  is preferably an O-ring disposed radially about the valve stem  46  and the O-ring type valve stem seal  50  is sized and dimensioned to seat in sealing relationship with the valve seat  52 . 
     As illustrated in the embodiments in drawings, the valve stem assembly  16  is disposed within the internal valve chamber  22  such that, when the valve stem  46  is in the extended valve stem  46  position, the valve stem protrudes through the valve stem opening  34  in the valve body cover  14  and the valve stem seal  50  is in sealing contact with the valve seat  52  so as to seal closed the valve stem opening  34 . Conversely, when the valve stem  46  is in the retracted valve stem position, the valve stem seal  50  becomes sufficiently spaced apart from the valve seat  52  so that the valve stem opening  34  is not sealed closed. The valve stem  46  is normally in the retracted position when the first open end  18  of the valve body  12  is attached to an appropriate connector. 
     As illustrated in the embodiments in the drawings, there is typically a safety relief member  54  attached by a threaded connection to the valve body  12  between the first open end  18  and the second open end  20 . The safety relief member  54  connects with the internal valve chamber  22  to allow gas to escape when the pressure within the internal valve chamber  22  becomes too high. 
     The pin valve  10  described herein is distinguished from pin valves  110  of the prior art by the detachable valve body cover  14  attached to the first open end  18 . As illustrated in FIG. 1, prior art pin valves  110  do not have a valve body cover  14  at the first open end  118 . Instead, prior art pin valves  110  have an access opening  156  in the second open end  120  of the valve body  112 . 
     The pin valve  10  is ideally used as a connection valve to connect a pressurized tank  190  to a pneumatically operated paint ball gun  200 . As illustrated in FIG. 4, the second open end  20  of the valve body  12  is attached to the pressurized tank  190  and the first open end  18  of the valve body  12  is attached to the paint ball gun  200 . In operation, a user repairs a pin valve  10  with a damaged valve stem  46  entirely from the first open end  18  simply by removing the valve body cover  14  with an alien wrench and replacing the valve stem assembly  16 . Replacing the valve stem assembly  16  is much simpler with the pin valve  10  described herein in comparison to a prior art pin valve  110 . With reference to the prior art pin valve  110  illustrated in FIG. 1, the valve stem assembly  116  cannot be removed from the first open end  118  of the valve body  112 , but rather may be removed and replaced only through an access opening  156  in the second open end  120  of the valve body  112 . Replacement of a valve stem  146  in a prior art pin valve  110  necessitates that the second open end  120  normally fixedly attached to a CO 2  tank by a special sealant be removed. 
     If the first open end  18  of the pin valve  10  is dented, the user repairs the embodiment of the invention illustrated in FIG. 2 by adding a new valve body cover  14  rather than replacing the entire pin valve  10 . Again, the repair is performed from the first open end  18  of the pin valve  10  after the first open end  18  has been disconnected. The valve body cover  14  is easy to remove and reattach because it incorporates an opening for an alien wrench. A user wishing to remove the valve body cover  14  knows whether the pressurized gas source has been discharged prior to removing the valve body cover  14  because engagement of the alien wrench to detach the valve body cover  14  necessarily pushes the valve stem  46  to a retracted position and opens the pin valve  10 . This eliminates the danger of accidentally removing the valve body cover  14  from the pin valve  10  when the pressurized gas source has not been discharged. 
     Finally, a user wishing to repair a defective valve seat  52  simply replaces the valve body cover  14 . This repair is performed from the first open end  18  of the pin valve  10 , rather than replacing the entire pin valve  10  or attempting to re-machine the valve seat  52  from the access opening at the second open end  20  of the pin valve  10 . The user need not remove the fixedly attached second open end  20  of the pin valve  10  to perform this repair. 
     Having thus described the invention, it should be apparent that numerous structural modifications and adaptations may be resorted to without departing from the scope and fair meaning of the instant invention as set forth hereinabove and as described hereinbelow by the claims.