Patent Publication Number: US-2004040551-A1

Title: Pressure gauge for pneumatic toy gun

Description:
BACKGROUND  
       [0001] The patent is directed to a pneumatic toy projectile launcher, and more particularly to a liquid-filled pressure gauge for indicating the amount of air pressure built up in a pneumatic toy projectile launcher.  
       [0002] Various pneumatic toy projectile launchers have been previously described. For example, U.S. Pat. No. 4,784,107 to Kelly discloses a ball pitching system comprising a pneumatically actuated pitching arm and automatic ball feed system. The pneumatic actuation is provided by an automatic pressure sensor valve. Compressed air is provided by a DC compressor affixed to the frame of the pitching apparatus and may be powered by a conventional  12  volt vehicular battery system. In this manner the preselected pitching of baseballs and the like along a predefined trajectory can be provided at remote locations away from conventional automotive electrical supply. A pressure gauge is disposed on a hollow frame section for monitoring the operation of the ball pitching system.  
       [0003] U.S. Pat. No. 5,337,726 to Wood discloses a pneumatic driven ball thrower employing a pressurized gas to move a piston and connecting rod against a ball at rapid velocity to move the ball a pre-determined velocity. The pressurized gas ram at a pre-determined amount of pressurized gas in a very brief period of time to rapidly accelerate the piston and rod. The device employs a pressurized gas reservoir in proximity to the pressurized gas ram employing a valve with a large gas passage which opens rapidly permitting rapid passage of the pressurized gas from the gas reservoir to the pressurized gas ram. The housing assembly of the ball thrower has a hand grip, a three-way valve with an inlet port and an exhaust port, a trigger and a gas pressure gauge.  
       SUMMARY OF THE INVENTION  
       [0004] In one aspect, the invention is directed to a pressure gauge for a pneumatic toy gun that may include a bottom flange having an inlet, an outlet, an orifice, a resilient bladder, and an upper housing having a hollow interior wherein the inlet, the outlet and the orifice are in fluid communication with each other. The upper housing may be connected to the bottom flange with the bladder being disposed between the upper housing and the bottom flange, and with the orifice of the bottom flange being disposed proximate a surface of the bladder. The bladder may be affixed to the bottom flange to form an air-tight seal between the surface of the bladder and the bottom flange such that compressed air in the bottom flange imparts force on the surface of the bladder to deflect the bladder into the interior of the upper housing. The bladder may further be affixed to the upper housing to form an air-tight seal between the opposite surface of the bladder and the upper housing.  
       [0005] The pressure gauge may further include a transparent tube connected to an end of the upper housing opposite the bottom flange and bladder with the tube being in fluid communication with the hollow interior of the upper portion and being affixed to the upper portion to form an air-tight seal between the transparent tube and upper portion, and a cap connected to an end of the transparent tube opposite the upper portion with the cap being affixed to the transparent tube to form an air-tight seal between the transparent tube and upper portion. The pressure gauge may include a fluid retentively disposed within a cavity defined by the bladder, the upper portion, the transparent tube and the cap, with the volume of the fluid in the cavity being less than the volume of the cavity formed by the bladder, the upper portion, the transparent tube and the cap.  
       [0006] In another aspect, the present invention is directed to a pneumatic toy gun which may include a cylinder having an open end and an outlet, a piston disposed within the open end of the cylinder, and a valve having a valve inlet and a discharge outlet. The valve may have a normal position wherein the discharge outlet is sealed to prevent the flow of air through the discharge outlet, and an open position wherein the discharge outlet is unsealed to permit the flow of air through the discharge outlet, with the outlet of the cylinder being in fluid communication with the valve inlet The pneumatic toy gun may further include a pressure gauge in fluid communication with the outlet of the cylinder and the valve inlet, with the pressure gauge having a cavity with a fluid disposed therein, and the cavity having a transparent portion through which the fluid is visible. Movement of the piston within the cylinder compresses air in the cylinder and the valve to increase the air pressure therein, and the amount of the fluid visible through the transparent portion of the pressure gauge may be proportional to the air pressure in the cylinder and the valve.  
       [0007] In a further aspect, the present invention is directed to a pressure gauge for a pneumatic toy gun having a pressurizing mechanism for compressing air within the pneumatic toy gun. The pressure gauge may include an enclosed housing forming a cavity wherein the interior of the cavity may be isolated from the ambient environment. The enclosed housing may comprise a transparent portion and a movable portion, such as a resilient bladder or sliding piston, in fluid communication with the pressurizing mechanism of the pneumatic toy gun, with the movable portion being adapted to move into the cavity of the enclosed housing by an amount proportional to a force applied to the movable portion by the compressed air within the pneumatic toy gun. The pressure gauge may further include a fluid disposed within the cavity of the enclosed portion, wherein the amount of the fluid visible in the transparent portion may be proportional to the movement of the movable portion under the force of the compressed air.  
       [0008] Additional aspects of the invention are defined by the claims of this patent. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a side view of an embodiment of a pneumatic toy gun having a pressure gauge in accordance with the invention;  
     [0010]FIG. 2 is a side view of the inside of the pneumatic toy gun of FIG. 1;  
     [0011]FIG. 3A- 3 C is a cross-sectional view of the pressure gauge of FIG. 1 with the pneumatic toy gun not pressurized;  
     [0012]FIG. 4A and 4B is a cross-sectional view of the pressure gauge of FIG. 1 with the pneumatic toy gun pressurized;  
     [0013]FIG. 5A and 5B is a cross-sectional of an alternative embodiment of a pressure gauge in accordance with the invention; and  
     [0014]FIG. 6A and 6B is a cross-sectional of an further alternative embodiment of a pressure gauge in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS  
     [0015] Although the following text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention.  
     [0016] It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting -the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. § 112, sixth paragraph.  
     [0017]FIG. 1 illustrates one possible embodiment of a pneumatic toy gun  10  having a pressure gauge  12  in accordance with the invention. The embodiment of the pneumatic toy gun  10  illustrated in FIG. 1 may be configured in the form of a toy gun that may be adapted to launch a plurality of toy darts from a corresponding plurality of barrels  14  of a rotatable magazine  16 . While the toy gun  10  as illustrated and described herein as having a plurality of barrels  14  for launching a plurality of toy darts, those skilled in the art will understand that pressure gauges  12  in accordance with the present invention may be implemented in pneumatic toy projectile launchers that launch other types of toy projectiles such as balls, disks, rings, rockets, and the like. The pressure gauges  12  may also be implemented in pneumatic launchers that discharge water, air, or other fluids, such as the water gun described in U.S. Pat. No. Re. 35,412, entitled “Double Tank Pinch Trigger Pump Water Gun,” which is hereby expressly incorporated by reference herein. The pressure gauge  12  may also be implemented in pneumatic toy projectile launchers that retain and launch a single toy projectile, or that launch any number of toy projectiles that are held by a magazine or other mechanism until discharged by the projectile launcher. Implementation of pressure gauges in accordance with the present invention in other types of projectile launchers with other types of toy projectiles will be understood by those skilled in the art in view of the disclosure herein.  
     [0018] The toy gun  10  illustrated in FIG. I has an outer housing  18  that may include a hand grip  20  and a moving handle  22  that are grasped by the user of the toy gun  10 . The handle  22  may slide within slots  24  in the housing  18  to drive a piston rod  26  and, consequently, an internal piston in a cylinder (not shown) to compress air within the toy gun  10  in preparation for launching a toy projectile. The housing  18  may further enclose a hose  28 , which may be visible through a transparent portion  30  of the housing  18 , which may be in fluid communication with the piston, the cylinder, and the pressure gauge  12  such that the pressure created by the piston and cylinder is measured by the pressure gauge  12 . When the toy gun  10  is pressurized, the amount of pressure may be indicated by the level of a fluid  32  within the pressure gauge  12  that is visible in a transparent tube  34  through an opening  35  in the housing  18 . As the pressure in the toy gun  10  increases, the level of the fluid  32  in the pressure gauge  12  may rise proportionately to provide the user with a visual indication of the amount of pressure in the toy gun  10 . The visual indication provided by the pressure gauge  12  may appear more dramatic by having a body  36  disposed within the transparent tube  34  to reduce the volume of the cavity within the pressure gauge  12 . With the reduced internal volume within the pressure gauge  12 , the fluid  32  in the transparent tube  34  will rise to a higher level for a given amount of pressure within the toy gun  10  than the level to which the fluid  32  would rise in the transparent tube  34  without the body  36  disposed therein. While the toy gun  10  illustrated herein includes one pressure gauge  12 , it is contemplated that multiple pressure gauges  12  may be provided in a toy gun  10 , with each pressure gauge  12  providing a visual indication of the air pressure in the toy gun  10 .  
     [0019] Once the toy gun  10  is pressurized, the air may be discharged and a toy projectile launched by the user pulling a trigger  38  that may extend out of the housing  18 . The trigger  38  may be a component of a firing mechanism within the housing  18  that causes the compressed air to be discharged and to act upon the toy projectile in a manner that causes the toy projectile to be propelled away from the toy gun  10 . When the compressed air is discharged, the air pressure within the toy gun  10  is reduced. The pressure gauge  12  may be in fluid communication with the release mechanism such that the release of air and reduction of the air pressure may be indicated by a reduced level of the fluid  32  in the pressure gauge  12 , with the level of the fluid  32  decreasing in proportion to the reduction in air pressure in the toy gun  10 .  
     [0020] Referring now to FIG. 2, one embodiment of pressure gauge  12  and internal mechanism of the toy gun  10  is illustrated. The toy gun  10  may include a pressurizing mechanism for preparing the toy gun  10  to be fired, and a firing mechanism for discharging the compressed air to launch the projectile or projectiles fired by the toy gun  10 . One embodiment of a pressurizing mechanism may include a piston assembly having the piston stem  26  and a piston head (not shown) disposed within a cylinder  40  so that movement of the piston stem  26  and piston head toward a closed end  42  of the cylinder  40  compresses air within the toy gun  10 . The pressurizing mechanism may further include the hose  28  extending between an outlet  44  of the cylinder  40  and an inlet  46  in a bottom flange  48  of the pressure gauge  12 , thereby placing the pressure gauge  12  in fluid communication with the cylinder  40 . As will be described more fully below, an air-tight seal exists between the bottom flange  48  and the remaining portions of the pressure gauge  12  that prevents the pressurized air from escaping into either the liquid-filled portion of the pressure gauge  12  or into the surrounding environment.  
     [0021] The bottom flange  48  may have a hollow interior or channel placing the inlet  46  in fluid communication with and outlet  50  such that pressurized air may pass through the bottom flange  48  and into a second hose  52 . The second hose  52  may be attached between the outlet  50  of the bottom flange  48  and an inlet  52  of a valve  54 , thereby placing the bottom flange  48  in fluid communication with the valve  54 . The valve  54 , which may be a poppet-type valve, may have a discharge outlet  56 , with the valve  54  being normally closed to prevent the release of the pressurized air from the toy gun  10  through the discharge outlet  56  prior to firing. Configured in this manner, the cylinder  40 , hoses  28 ,  52 , bottom flange  48 , and the valve  56  form an air-tight compartment that retains compressed air until the valve  54  is opened by the firing mechanism.  
     [0022] To allow the user to pressurize the toy gun  10 , the handle  22  may be attached to the piston rod  26  at a collar  60 . The handle  22  may include posts  62 , one of which may engage the collar  60  of the piston rod  26 , disposed within the slot  24 . The slot  24  may constrain the handle  22  and piston rod  26  to move linearly parallel to the longitudinal axis of the cylinder  40  in order to compress air in the pressurizing mechanism. The outlet  44  may include a one-way valve to allow the user to pump the handle  22  multiple times for greater pressurization by preventing air in the hose  28  from passing back into the cylinder  40  when the handle  22  and piston are drawn forward. As the user pumps the handle  22  one or more times to pressurize the air in the toy gun  10 , the level of the fluid  32  in the pressure gauge  12  rises in proportion to the amount of pressure such that the fluid  32  is visible through the transparent tube  34  and the opening  35  in the housing  18 . While the pressurizing mechanism is illustrated and described herein as having a piston and cylinder having linear movement to compress air, those skilled in the art will understand that other compression mechanisms, such as bellows, compressed air cartridges, and the like, and methods of achieving pressurization, such as providing a pivoting handle that pressurizes air as the user pivots the handle through its range of motion, are contemplated as having use in toy guns incorporating pressure gauges in accordance with the present invention.  
     [0023] Once pressurized, a firing mechanism of the toy gun  10  controls the discharge of the pressurized air to launch the toy projectile, projectiles, water, etc. The firing mechanism may include the valve  56  which may include an internal stop having a normal position that seals the discharge outlet  58  to maintain the pressure in the toy gun  10 , and a discharge position wherein the stop is disengaged from the discharge outlet  58  to allow the pressurized air to pass out of the valve  56  through the discharge outlet  58 . The position of the internal stop of the valve  56  may be controlled by a valve stem  66  operatively coupled to the stop within the valve  56  and extending outwardly from the valve  56 . When the valve stem  66  is displaced to the left as shown FIG. 2, the internal stop is unseated from the discharge outlet  58  for allow the discharge of the pressurized air.  
     [0024] In order to simulation the firing of a pistol, the valve stem  66  may be operatively coupled to the trigger  38  such that as the trigger  38  is grasped and pulled rearward by the user, the tension on the trigger  38  increases until the firing mechanism is released and the valve stem  66  is displaced to allow the discharge of the pressurized air. The trigger  38  may include a collar  68  disposed and slidable on the outer surface of the cylinder  40  to move the trigger  38  parallel to the longitudinal axis of the valve stem  66 . The trigger  38  may further include an arm  70  extending upwardly and partially encompassing the valve stem  66  so that the arm  70  moves along the valve stem  66  without directly engaging and moving the valve stem  66 . The trigger  38  may be maintained in the normal forward position under the urging of a spring  72  disposed between the rearward portion of the trigger  38  and a rear bearing surface  74  of the housing  18 . While the trigger  38  and accompanying mechanism are illustrated and described in FIG. 2 as moving linearly, it will be apparent to those skilled in the art that the trigger mechanism may be adapted or configured to rotate or move through any other range of motion that causes the firing mechanism to fire the toy gun  10 .  
     [0025] The firing mechanism may further include a ram  76  that is slidable on the valve stem  66  between the arm  70  of the trigger  38  and a stop  78  that is formed in or rigidly connected to the valve stem  66  rearward of the arm  70  of the trigger  38 . Still further, a spring  80  may be disposed about the valve stem  66  between the arm  70  and the ram  76  and connected to the arm  70  and the ram  76  such that movement of the arm  70  results in either corresponding movement of the ram  76  or an increased force of the spring  80  on the ram  76 . To further simulate the firing of a pistol, a pawl  82  may be disposed between the ram  76  and stop  78  when the trigger  38  is disposed in the normal forward position. The pawl  82  may be pivotable about a shaft  84  to allow the pawl  82  to move between a first position wherein the pawl  82  engages the ram  76  to prevent rearward movement of the ram  76  toward the stop  78 , and a second position wherein the pawl  82  is disengaged from the ram  76  to allow the ram  76  to move toward the stop  78  under the urging of the spring  80 .  
     [0026] To actuate the firing mechanism, the user grasps the hand grip  20  and draws the trigger  38  rearward. As the trigger  38  moves rearward, the collar  68  slides on the cylinder  40  and arm  70  moves rearward toward the ram  76  and stop  78 . The pawl  82 , which is disposed in the first position under the urging of a spring  86 , engages the ram  76  to prevent the ram  76  from moving rearward as the rearward movement of the arm  70  compresses the spring  78 . The spring  78  continues to compress and increase the force on the ram  76  as the trigger  38  and arm  70  move rearward until an engagement surface  88  of the trigger  38  engages the pawl  82 . The engagement surface  88  causes the pawl  82  to rotate toward the second position as the trigger  38  continues to move rearward. Eventually, the pawl  82  rotates out of engagement with the ram  76 . Once the pawl  82  disengages the ram  76 , the ram  76  is thrust toward the stop  78  by the force of the spring  78  so that the ram  76  impacts the stop  78  with sufficient momentum to cause the valve stem  66  to move rearward. As the valve stem  66  moves rearward, the internal stop within the valve  56  is unseated from the discharge outlet  58 , thereby releasing the pressurized air. The pressurized air is expelled through the discharge outlet  58  and through an orifice in the magazine  16  corresponding to one of the barrels  14  that is aligned with the discharge outlet  58  in a manner that projects a toy projectile disposed in the aligned barrel  14 . As the pressurized air is discharged through the discharge outlet  58 , the reduction in air pressure within the toy gun  10  is reflected visually in the pressure gauge  12  as the level of the fluid  32  is reduced in proportion to the reduction in air pressure.  
     [0027] When the trigger  38  is released after firing the toy gun  10 , the firing mechanism is reset as the trigger  38  is biased forward to its normal position by the spring  72 . As the arm  70  moves forward along with the trigger  38 , the ram  76  is drawn forward by the spring  78  past the pawl  82 . When the ram  76  is disposed forward of the pawl  82 , the pawl  82  rotates back to its initial position under the urging of the spring  86 .  
     [0028] As previously discussed, the toy gun  10  may further include a magazine  16  having a plurality of barrels  14  that move into and out of alignment with the discharge outlet  58  to launch a plurality of toy projectiles. In order to move the barrels  14  into and out of alignment, the toy gun  10  may further include an indexing mechanism, which may be of the type shown in FIG. 2. The indexing mechanism may be driven by the movement of the handle  22  when the toy gun  10  is pressurized. The indexing mechanism may include a cam surface  90  connected to or formed with the collar  60  that engages a pivoting arm  92  when the handle  22  is drawn rearward. The engagement of the pivoting arm  92  by the cam surface  90  may cause rotation of the pivoting arm  92  about an axis parallel to the direction of motion of the handle  22  such that the pivoting arm  92  may cause a corresponding rotation of a drive arm  94  operatively coupled thereto. The drive arm  94  may in turn drive a ratchet mechanism  96  that facilitates rotation of shaft  98  of the magazine  16  in one direction and prevents rotation of the shaft  98  in the opposite direction.  
     [0029] Movement of the cam surface  90  past the pivoting arm  92  causes the pivoting arm  92  to rotate through an angle that causes the magazine  16  to rotate through an arc that brings the next barrel  14  into alignment with the discharge outlet  58 . When the desired angle is achieved by the pivoting arm  92 , the pivoting arm  92  may be engaged by a locking arm  100  to prevent the pivoting arm  92  from returning to a position in which the pivoting arm may be driven by the cam surface  90 . At this point, the indexing mechanism is set for discharge of the pressurized air by the firing mechanism. When the trigger  38  is pulled and the valve stem  66  is driven rearward by the impact of the ram  76 , a second ram  102  disposed on and moving with the valve stem  66  may impact the locking arm  100  to release the pivoting arm  92 , freeing the locking arm  92  to rotate back into position to be driven by cam surface  90  when the toy gun  10  is re-pressurized. The indexing mechanism shown in FIG. 2 is illustrative only, and those skilled in the art will understand that other indexing mechanism configurations for moving each of a plurality of toy projectiles into alignment with that discharge outlet  56  for firing may be implemented in pneumatic compressed air launchers having pressure gauges  12  in accordance with the present invention. For example, the indexing mechanism may be driven by the movement of the trigger during actuation of the firing mechanism. Also, a linear magazine or a belt may be substituted for the circular magazine  16  shown herein.  
     [0030]FIG. 3A- 3 C illustrate a first embodiment of a pressure gauge  12  in accordance with the present invention. Referring to FIG. 3A, which shows the normal state of the pressure gauge  12  when the toy gun  10  is not pressurized, the pressure gauge  12  may be filled with fluid  32  and have a transparent tube  34  through which the fluid  32  may be visible when sufficient air pressure is built up in the toy gun  10 . While the transparent tube  34  as shown has a generally cylindrical shape, it will be understood that the tube  34  may be spherical, cubic, conical or have any other geometry. As previously discussed, the pressure gauge  12  may have a bottom flange  28  having an inlet  46  having hose  28  connected thereto in fluid communication with an outlet  50  having hose  52  connected thereto via a channel  104 . The bottom flange  48  is connected to an hollow upper housing  106  with a flexible bladder  108  disposed therebetween. The bottom flange  48  and upper housing  106  are joined together by fasteners, adhesive, threads, or other connection methods such that air-tight seals are formed between the bottom flange  48  and the bladder  108 , and between the bladder  108  and the upper housing  106 . The bottom flange  48  may further include an orifice  110  disposed between the channel  104  and the bladder  108  and placing the bladder  108  in fluid communication with the channel  104  so that the force of the pressurized air within the toy gun  10  and, consequently, the channel  104  bears upon the bladder  108 .  
     [0031] The upper housing  106  and bladder  108  form a reservoir for holding some or all of the fluid  32 , depending on the amount of air pressure in the toy gun  10 . The hollow transparent tube  34  may be disposed at the top of the upper housing  106  and connected to the upper housing  106  in a manner that provides an air-tight seal to prevent the fluid  32  from leaking out of the pressure gauge  12  at the interface of the upper housing  106  and transparent tube  34 . A cap  112  may be disposed at the end of the transparent tube  34  opposite the upper housing  106  and also connected to the transparent tube  34  in a manner that provides an air-tight seat. Alternatively, the upper housing  106 , transparent tube  34 , and cap  112  may be integrally formed as a single component consisting of two or all three of the separate components. Assembled in this manner, the upper housing  106 , bladder  108 , transparent tube  34  and cap  112  form a sealed cavity isolating the fluid  32  contained therein from the ambient environment. The pressure gauge  12  may further comprise the body  36  within the transparent tube  34  occupying a portion of the volume of the tube  34 . As shown in FIG. 3A, the body  36  may be in the form of a stalactite suspended from the inside of the cap  112 . However, the body  36  may alternatively be connected to the tube  34 , upper housing  106  or the bladder  108 , or be detached and free to move within the interior of the pressure gauge  12 .  
     [0032] The operation of the pressure gauge  12  is illustrated in FIGS.  3 A- 3 C. In FIG. 3A, the toy gun  10  is in a relatively unpressurized state whereby the force applied by the air in the hoses  28 ,  52  and the channel  104  through the orifice  110  is insufficient to cause the bladder  108  to deflect into the upper housing  106 . In this state, the fluid  32  may be entirely contained within the upper housing  106  such that the fluid  32  is not visible through the transparent tube  34 , thereby indicating to the user that the toy gun  10  is not pressurized. Referring to FIG. 3B, the toy gun  10  has been partially pressurized so that the force of the compressed air exerted on the bladder  108  through the orifice  110  is sufficient to cause the bladder  108  to deflect upwardly into the interior of the upper housing  106 . As the bladder  108  deflects into the upper housing  106 , the volume within the upper housing  106  is reduced, thereby forcing the fluid  32  upward into the transparent tube  34  where the fluid  32  is visible to the user of the toy gun  10 . As the air pressure within the toy gun  10  increases with additional pumping of the handle  22 , the deflection of the bladder  108  due to the force of the compressed air increases and the level of the fluid  32  continues to rise as shown in FIG. 3C. Once the level of the fluid  32  reaches the body  36  and the volume of the transparent tube  34  is reduced, the fluid level increases at a faster rate in relation to the deflection of the bladder  108 , thereby providing a more dramatic visual indication of the increase in air pressure within the toy gun  10 . When the toy gun  10  is fired and the compressed air is discharged from the valve  56 , the force exerted on the bladder  108  is reduced and the resiliency of the bladder  108  causes the bladder  108  to return toward its normal position. As the bladder  108  returns to the normal position, the volume within the upper housing  106  is recaptured, thereby allowing the level of the fluid  32  to lower until the fluid  32  is again contained within the upper housing  106  and no longer visible to the user as shown in FIG. 3A.  
     [0033] Referring now to FIGS. 4A and 4B, an alternative embodiment of a pressure gauge  12  according to the present invention may include a body  36  extending the entire length of the transparent tube  34  such that the volume within the tube  34  is further reduced and the level of the fluid  32  may increase at a greater rate throughout the pressurization of the toy gun  10  from the unpressurized state of FIG. 4A to the pressurized state of FIG. 4B. In another alternative embodiment shown in FIGS. 5A and 5B, the body  36  may be in the form of a cone or plum, such that the rate of increase in the level of the fluid  32  increases at an increasing rate as the air pressure in the toy gun  10  increases from the upressurized state of FIG. 5A to the pressurized state of FIG. 5B. In a still further alternative embodiment illustrated in FIGS. 6A and 6B, the body  36  is in the form of a detached sphere that floats on the surface of the fluid  32 . As the toy gun  10  is pressurized and de-pressurized, the height of the sphere changes as the level of the fluid  32  increases and decreases to indicate the pressure within the toy gun  10 .  
     [0034] While the pressure gauge  12  is illustrated having the bladder  108  that moves into the upper housing  106  by deflecting under the force of the compressed air, it is contemplated that other types of movable components may be implemented in pressure gauges  12  in accordance with the invention that will reduce the volume inside the pressure gauge  12  and cause the fluid  32  to be visible in the transparent tube  34 . For example, the bladder  108  may be replaced with a piston that is slidable within the upper portion  106 . The piston may include an O-ring or other type of seal so that the piston may engage the upper housing  106  to slide in the upper housing  106  while maintaining an air-tight seal to isolate the interior cavity of the pressure gauge  12 . The piston may be in fluid communication with the pressurizing mechanism so that the force of the pressurized air tends to push the piston into the pressure gauge  12 , thereby reducing the volume of the interior of the pressure gauge  12  in a similar manner as the deflecting bladder  108 . When the air pressure is reduced, the piston may return to its initial position under the urging of gravity, the compressed air and fluid in the pressure gauge  12 , a return spring, or other type of biasing mechanism.  
     [0035] Thus, while the present invention has been described with reference to specific examples, which are intended to be illustrative only and not to be limiting of the invention, it will be apparent to those of ordinary skill in the art that changes, additions or deletions may be made to the disclosed embodiments without departing from the spirit and scope of the invention.