Abstract:
An adjustable floating seal piston type pressure regulator valve of the type wherein a spring biased piston engages a floating seal in a regulator body valve chamber to open and close a valve seat outlet in the valve chamber. The valve seat comprises a separate member from the regulator body and is adjustably movable in the valve chamber toward and away from the piston, such that movement of the valve seat toward the piston serves to lower a regulated outlet pressure and movement of the valve seat away from the piston serves to increase the regulated outlet pressure. The valve seat member is moved by an adjustment screw that is externally accessible by an adjustment tool. A tubular expansion chamber surrounds the regulator body and provides an enlarged expansion chamber that reduces valve recycle time. Convolutions or ribs in the expansion chamber housing enhance heat through transfer to the valve gases.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to fluid flow pressure regulators and more particularly to an easily adjustable secondary pressure regulator having an expansion chamber that improves recycle time. 
   Fluid flow pressure regulators are used for a number of purposes. Pressure regulators include primary pressure regulators and secondary pressure regulators. These can be used for a number of gases, including carbon dioxide (CO 2 ). One such use for such pressure regulators is for gas-powered weapons, such as paintball guns. A primary regulator typically is not adjustable and reduces line pressure from about 3500 or 4800 psi to 500–800 psi. A secondary regulator may be adjustable and reduces pressure from 500–800 psi to any one of a number of operating ranges, such as 150–250 psi, 250–350 psi, and 350–450 psi. A different model of secondary pressure regulator may be used for each secondary pressure range. 
   Adjustable pressure regulators are known. An adjustable pressure regulator employing replaceable floating valve seals of different thicknesses is shown in U.S. Pat. No. 6,056,006, the disclosure of which is incorporated by reference. Floating valve seals are desirable because they tend to seat on a valve seat without skewing. Replacement of seals to achieve adjustment, however, can be inconvenient. 
   An object of the present invention is to provide an improved pressure regulator of the floating seal or floating “chip” design wherein the output pressure can be varied without replacing the floating seal. 
   Another object of the present invention is to provide a compact secondary pressure regulator employing an expansion chamber that can be precharged and reduces cycle time. 
   SUMMARY OF THE INVENTION 
   The present invention comprises an improvement in a floating seal piston type pressure regulator valve wherein a spring biased piston reciprocates in a valve chamber of a regulator body to open and close a valve opening in a valve seat in the valve chamber by means of a floating seal positioned between the piston and the valve seat. In the present invention, the valve seat comprises a separate member from the regulator body and is adjustably movable in the valve chamber toward and away from the piston, such that movement of the valve seat toward the piston serves to lower a regulated outlet pressure and movement of the valve seat away from the piston serves to increase the regulated outlet pressure. 
   The regulator body includes a regulator body inlet in fluid communication with the valve chamber. The movable valve seat has a valve seat inlet in communication with the regulator body inlet and a valve seat outlet that is in communication with a regulator body outlet when the valve seat outlet is open. The regulator body inlet is isolated from the regulator body outlet when the valve seat outlet is closed by the piston pressing the floating valve seal over the valve seat outlet. The valve seat member thus isolates the valve chamber inlet from the valve chamber outlet except to the extent that communication is provided through the valve seat outlet. 
   The valve seat member can be drivingly connected to a threaded adjustment screw rotatably mounted in the valve body, such that rotation of the adjustment screw moves the valve seat toward or away from the piston and floating seal. Desirably, the valve seat member is aligned with the piston and is axially movable with respect thereto, the adjustment screw being axially aligned with the piston and connected between the valve seat member and valve body such that rotation of the adjustment screw moves the valve seat in an axial direction with respect to the valve body. The adjustment screw has an externally accessible connector for the attachment of a rotation tool thereto. 
   Another feature of the invention is that the regulator further comprises an expansion chamber housing surrounding the valve body that provides an enlarged interior expansion chamber. The expansion chamber has an inlet in communication with a source of pressurized fluid and has an outlet in communication with the valve chamber in the valve body. The expansion chamber serves to precharge the pressure regulator and reduce recycle time. Desirably, the valve body has an elongated cylindrical shape, and the expansion chamber housing comprises a tubular member that fits over the body, with the expansion chamber comprising an annular cavity between the expansion chamber housing and the valve body. 
   As another feature of the invention, the expansion chamber housing comprises a plurality of spaced annular ribs or convolutions on an outer surface thereof, the ribs enhancing heat transfer to the expansion chamber through the exterior of the expansion chamber housing. 
   These and other features and advantages of the present invention will hereinafter appear and for purposes of illustration but not of limitation, a preferred embodiment of the present invention is described below and shown in the appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The drawing FIGURE is a longitudinal section view of a pressure regulator of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to the drawings, pressure regulator  10  includes regulator body  12  mounted in expansion chamber housing  14  that surrounds the body on one side of an outwardly extending radial flange  16 . An external retaining ring  18  fits in a groove  20  in end  22  of regulator body  12  and holds the expansion chamber housing  14  on the body between the retaining ring and flange  16 . A lower housing seal  24  that fits in a groove  26  adjacent rear end  22  of the regulator body housing is positioned between regulator body  12  and expansion chamber housing  14  and restrains pressure leakage through the end of the expansion chamber housing. An upper housing seal  25  at the other end of the body  12  fits in groove  27  and prevents fluid leakage from the other end of the expansion chamber housing. Regulator body  12  can have a ribbed outer surface  28  that serves as a hand grip and provides increased external surface for thermal transfer. 
   Expansion chamber housing  14  has a cylindrical interior surface  30  that is spaced outwardly from outer wall  32  of regulator body  12  so as to provide an annular expansion chamber  34  around the exterior of the regulator body. An opening  36  extends between the expansion chamber  34  and a cylindrical interior opening that forms a valve chamber  38  in the interior of regulator body  12 . A valve inlet  40  provides an opening from the exterior of the expansion chamber housing  14  into communication with expansion chamber  34 . 
   An outlet end  41  of regulator body  12  includes an annular flange  42  extending outwardly from radial flange  16 . A smaller diameter annular flange  44  extends outwardly from an outlet end of cylindrical valve chamber opening  38 . 
   A recessed groove  46  is positioned between flanges  42  and  44 , and a coil compression spring  48  is mounted in the groove and extends axially outwardly therefrom. 
   A piston  50  having an inner portion  52  of narrower diameter and an outer portion  54  of larger diameter is positioned in axial alignment with valve chamber  38 , with the inner portion  52  of the piston being mounted slidably in an open end of the valve chamber. The interior of the valve chamber thus serves as a cylinder wall for inner piston  52 . The distal end  56  of inner piston  52  is of smaller diameter than piston  52  and includes an inlet opening  58  therein. An O-ring seal  60  surrounds distal end  56  at a position behind opening  58  and resists gas leaks from the valve chamber between piston  52  and the wall of valve chamber  38 . 
   The outer portion  54  of piston  50  engages an interior cylinder wall  70  of bonnet  72  and is axially movable therein. A low pressure O-ring piston seal  74  positioned in a groove  76  in outer piston  54  prevents gas leaks from an interior chamber  78  (between piston  52  and the interior of bonnet  72 ). 
   An outer end portion  80  of bonnet  72  includes a opening  82  having an enlarged end  83  adjacent piston  50  that extends to a valve outlet  84  through a reduced diameter neck  86 . An annular inner end  85  of bonnet  72  is threaded or otherwise attached on the exterior of annular flange  42 . A bonnet nose seal  87  seals the end of the regulator valve in the paintball gun or other appliance in which it is mounted. 
   Pressurized gas flows through the pressure regulator  10  in a direction from valve inlet  40  to valve outlet  84 , with pressurized gas typically being introduced into valve inlet  40  at approximately 500–800 psi and typically exiting from valve outlet  84  at between 150 and 450 psi. Gas flows from inlet  40  through expansion chamber  34  then through opening  36  into valve chamber  38 . Gas then flows through a valve seat  96  to opening  58 , which leads to an interior opening  90  in piston  50 . Piston opening  90  leads to bonnet opening  82  and valve outlet  84 . 
   Pressure is controlled by the pressure regulator by means of generally cylindrical valve seat  96  mounted in generally cylindrical valve chamber  38 . Valve seat  96  includes a front end  98  and a rear end  100  that extend to the surface of valve chamber  38 , with O-rings  102  and  104  in ends  98  and  100  restricting gas passage thereby. A recessed interior portion  106  of valve seat  96  is in communication with inlet port  36  from the expansion chamber. A valve outlet conduit  110  extends from an inlet opening  111  in communication with recessed portion  106  to an outlet opening  112  in a conically tapered end  114  of valve seat  96 . Gas from the expansion chamber thus passes through port  36  into outlet opening  111  in the valve seat and then out through the outlet  112  in end  114  of the opening. 
   A floating valve seal or “chip”  118  fits in the valve chamber so as to be axially movable therein and is positioned between the distal end  56  of piston  50  and tapered outer end  114  of valve seat  96 . The seal  118  has a generally square or triangular axial cross sectional shape or other shape that provides a gas passage between the outer periphery of the seal and the wall of the valve chamber. 
   The secondary gas pressure at valve outlet  84  is a function of the distance between valve seal chip  118  and end  114  of the valve seat. The reason for this is as follows: when valve inlet  40  is connected to a source of pressurized gas, such as CO 2  (typically in the range of 500–800 psi) and when valve outlet  84  is closed (as when an attached paintball gun is not being fired) pressure equalizes within the interior of the valve body until the force exerted by the gas pressure in chamber  83  on the end of enlarged outer portion  54  of piston  50  exceeds the force exerted by the pressure of the gas on the small end  56  of the piston plus the outward force exerted by spring  48  on the inner side  128  of outer piston  54 . When the force exerted by the pressure in chamber  83  on the outer end of piston  54  exceeds the sum of the spring pressure and the pressure on the smaller end of piston  52 , piston  50  is moved to the left until valve seal  118  is pressed against opening  112  in tapered outlet  114 . This blocks any further gas movement through the valve into chamber  82  and thus limits the pressure in that chamber to the pressure existing at the time that the valve seal  118  closes opening  112  in the valve seat. Since the pressure of spring  48  (which is a compression spring) increases with increased compression, it can be seen that an increase in the distance between the valve seal  118  and the end  114  of the valve seat requires greater spring compression in order to close the valve and thus provides a higher secondary pressure in the outlet end of the pressure regulator. 
   The adjustable regulator shown in U.S. Pat. No. 6,056,006 achieves a variable secondary valve outlet pressure by changing the floating valve seal. A thicker seal results in a lower valve outlet pressure, whereas a thinner seal results in a higher valve outlet pressure. 
   In the present invention, a single purpose valve seal  118  can be used and pressure regulation can still be achieved by the use of a novel, movable valve seat  96 . Valve seat  96 , as stated above, is mounted in valve chamber  38  for axial movement toward and away from valve seal  118 . The valve seat is movable in the valve chamber by means of an adjustment screw  120  that is received in a threaded opening  122  in end  22  of the regulator body  12 . 
   Adjustment screw  120  has an inner end  126  that is received in a threaded opening in the outer end of valve seat  96 . The adjustment screw  120  is threaded securely into the valve seat  96 , such that the valve seat rotates with rotation of the adjustment screw  120 . Rotation of adjustment screw  120  in the valve seat thus moves the valve seat  96  toward or away from valve seal  118 , depending on the direction of rotation by the adjustment screw. The adjustment screw can be rotated by a conventional hex wrench through a hex wrench socket  124  at an outer end of the adjustment screw. 
   By rotating the adjustment screw, the end  114  of the valve seat  96  can be adjusted toward and away from the valve seat  118  and the end  56  of piston  50  to alter the output pressure of the regulator. This adjustment screw makes it possible to adjust the pressure of the secondary pressure regulator easily with a conventional hex wrench or the like and does not require disassembly of the pressure regulator to replace the valve seat chip with a chip of different thickness. 
   Another feature of the present invention is the incorporation of a relatively large but compact expansion chamber  34  around regulator body  12 . This large expansion chamber provides about three times the volume of gas as a conventional regulator and permits the pressure regulator to be pre-charged before a discharge of the pressure regulator. In a paintball gun application, for instance, when a conventional pressure regulator is used, there can be as much as a 50 psi pressure drop each time the gun is shot and there is a significant time lag for pressure to build up in the pressure regulator before a full charge of the pressure is available for a second shot. In the present invention, when a paintball gun is discharged, there is only about a 10 psi pressure drop during continuous firing, and the regulator is almost instantly recharged when firing is stopped. 
   Another feature of the present invention is that the ribbed outer surfaces  28  of the expansion chamber housing serve as heat sink, allowing the CO 2  gas (which is very cold) to warm up more readily. As the gas becomes warmer, this creates more gas pressure. The extra surface area provided by convolutions  28  increases the gas pressure in the expansion chamber due to the warming of the cold CO 2  gas in the interior of the expansion chamber. 
   It should be recognized that the foregoing is merely exemplary of the preferred practice of the present invention and that various changes in the arrangements and details of construction of the embodiments disclosed herein may be made without departing from the spirit and scope of the present invention.