Gas cartridge piercer and regulating valve

APPLICATION

The mechanism of this invention can be incorporated in a dispensing device of the type described in U.S. Ser. No. 525,023, filed on Feb. 4, 1966, now U.S. Patent No. 3,420,418 by Paul R. Rousset et al.

BACKGROUND OF THE INVENTION

Field of the invention

This invention relates to a valve mechanism for controlling the discharge of pressurised gas from a container.

Description of the prior art

A known valve mechanism of this type includes a valve member movable towards and away from an orifice through which gas can flow from the container; biassing means for urging the valve member towards a position in which it blocks the orifice, and actuating means adapted to overcome the effect of the biassing means for unblocking the orifice and permitting the flow of gas from the container. The gas in the container being highly-compressed, it may not be easy to position the actuating means so that the pressure in a space supplied with gas from the container does not rise at an excessive rate or to an excessive value. If this space is provided with a safety valve, it is possible for the safety valve to open more frequently than intended so that gas will be vented and thus wasted.

SUMMARY OF THE INVENTION

The valve mechanism includes two chambers on opposite sides of a slidable piston carrying a bulb-piercing and bulb-sealing pin. One chamber is vented to atmosphere and the other is on the upstream side of a small orifice through which all the gas flows to the outlet. When the pressure in this chamber rises sufficiently because of excess flow the piston is forced to move so that the pin re-seals the orifice it has made in the bulb seal. Thus the mechanism operates as a type of pressure feedback system to limit pressure rises or rates of flow.

BRIEF DESCRIPTION OF THE· DRAWING

The present invention will now be described by way of example with reference to the accompanying drawing, which is a diagrammatic sectional elevation showing the valve mechanism of the present invention fitted to a dispensing device of which only part is illustrated.

The dispensing device includes a body 2 having in it a bore 4 of which only part of the wall is shown. Mounted in the bore for movement along its axis is a main valve member 6 of which the lower end (not shown) operates a valve (also not shown) to control the flow of liquid from the upper end of a supply tube dipping into the can, to an outlet spout. Movement of the valve member 6 is controlled by movement of a handle (not shown). As the main valve operating mechanism does not form part of the subject matter of the present invention it is not described in further detail.

The body 2 of the device is formed with a hollow boss 8 which projects into the interior of a recess indicated generally by reference 10 and formed principally of an outlet chamber 12, an expansion chamber 14, and a reference chamber 16. The outlet 13 of chamber 12 is adapted to be placed in communication with the free space above the liquid in the can by means which is not shown.

The boss 8 supports a cam follower 18 which is slidable along the axis of the cylindrical passage in the boss under the control of the main valve 6. The cam follower 18 carries a ball 20 mounted at the outer end of a recess housing a mass 22 of resilient material biassing the ball 20 outwardly of the follower 18. The ball 20' is aligned with a cam surface 24 on the members 6 so that as member 6 moves up or down as viewed in the drawing the follower 18 is able to move horizontally. The valve member 6 is in fluid-tight engagement with the walls of the bore 4, or with a bush 26 therein, by means of O-ring seals 28. Similarly the cam follower 18 is sealed to the walls of the passage in the boss 8 by means of an O-ring 30.

Positioned in the recess 10 is a barrier member 32 rather similar in form to a cup seal. Member 32 acts as a barrier between outlet chamber 12 and expansion chamber 14, the two chambers being in communication with each other through a narrow passage 34 in member 32. Member 32 is in fluid-tight engagement with the annular end face of the boss 8, by means of an integral circular rib 36, and is in fluid-tight engagement with the cylindrical wall of the recess 10 by means of a flange 38 shaped so that a pressure difference between the expansion chamber 14 and the outlet chamber 12 is effective to force the flange 38 into firmer engagement with the outer wall of the recess 10. Thus the only path for gas from the expansion chamber 14 to the outlet chamber 12 is through the passage 34, of which more than one may be provided in member 32.

Also positioned in the recess 10 is a carrier member 40 which acts as a movable partition between expansion chamber 14 and reference chamber 16. Carrier 40 has a cylindrical head which is slidable along the outer cylindrical surface of the recess 10, and is kept in fluid-tight engagement therewith by means of an O-ring seal 42. The carrier 40 also has a cylindrical portiop of smaller diameter which is a sliding fit in the passage in the boss 8. Although the carrier 40 is not mechanically secured to follower 18 it is normally held in engagement with it so that the two members move in unison by inwardly-directed forces which act on the combination.

Mounted in the carrier for relative motion along the axis of the passage in the boss 8 is a plunger 44 formed at one end with a conical point 78 for piercing the seal 60 of a bulb 46 containing carbon dioxide under high pressure.

Mounted in a peripheral groove in member 44 is a circlip 48 of resilient material. The adjacent radial surface of carrier 40 is provided with an annular recess 49

3,459,331 so as to define a radially-spaced annular seat 50 which the outer part of the circlip 48 is adapted to contact. When the circlip is unstressed it lies in line with a surface defined by the seat 50. However when a sufficient axial force is exerted on the plunger 44 it is able to move axially in the appropriate direction by compression of mass 22 of resilient material and by flexure or “dishing” of the circlip 48, the extent of which is limited by the circlip coming into contact with the base of the recess 49. Thus the combined effect of the compressed mass 2 and the flexed circlip 48 is to bias the plunger 44 towards the bulb 46.

Screw-threaded in a continuation of the inner walls of the recess 10 is a support 80 comprising a cylindrical wall 52 in which is mounted an O-ring 54 adapted to make a fluid-tight seal with the neck of the bulb 46. The support 80 also comprises an end wall 56 provided with a central aperture 58 through which extends the pointed end 78 of the plunger 44. When the bulb is positioned relatively to the support 80 the seal 60 of the bulb is axially aligned with the passage 58 and with the end of the plunger 44 so that relative axial movement of the plunger and bulb towards each other is effective to cause the pointed end 78 of the plunger 44 to pierce the seal 60. The metal of the seal 60 is reltaively ductile so that an appropriate axial bias on the plunger 44 is able to keep the pointed end of the plunger seated so firmly in the hole it has made through the seal 60 that the flow of carbon dioxide from the bulb is completely blocked.

Retained by a washer 62 on wall 56 is one end of a sleeve 64 of resilient material which extends into the interior of the substantially-cylindrical recess 66 in the carrier 40. A helical compression spring 68 extends between the washer 62 and the circlip 48 so as to bias the plunger 44, and with it the carrier 40, away from the support 80. The sleeve 64 shrouds a major portion of the axial length of the spring 68.

A passage 70 in the carrier 40 places the interior of the recess 66 into communication with the expansion chamber 14, and the pointed end 78 of the plunger 44 is a relatively-loose fit in the aperture 58 so that any gas which emerges through the hole in the seal 60 is able to pass into the recess 66.

The reference chamber 16 is in communication with the atmosphere through a passage 72. Thus when gas under pressure passes into the interior of the recess 66, a radial differential pressure is exerted on the sleeve 64 so that the lip 74 at the outer end of the sleeve is forced into fluid-tight engagement with the cylindrical wall of the recess 66 to prevent gas escaping to the atmosphere.

Connected between the interior of the outlet chamber 12 and the atmosphere is a pressure-relief valve shown diagrammatically at 76.

Under the rest conditions illustrated in the drawing the pointed end 78 of the plunger 44 is in sealing engagement with the hole which it has made in the seal 60, being kept in engagement by the axial bias imparted by compression of the mass 22 and by flexure of the circlip 48. The spring 68 is effective to bias the carrier 40 and follower 18 to the left as viewed in the drawing, so that the ball 20 is in engagement with the valve member 6 under the force exerted on the ball 20 by the resilient mass 22. The pressures of the outlet chamber 12 and the expansion chamber 14 are equal to each other and to the pressure of the gas above the surface of the beer or oher liquid in the can to which the dispensing device is attached, the spaces being intercommunicated by passage 34 and outlet 13.

When it is desired to dispense beer from the can, the valve member 6 is moved upwardly. The presence of the cam track 24 enables the cam follower 18 and carrier 40 to move to the left as the spring 68 decompresses, but the effect of the resilient mass 22 and the flexed circlip 48 is initially to keep the plunger 44 in sealing engagement with a hole it has made in the seal 60 by permitting the carrier to move relatively to the plunger. However after movement for a short distance the mass 22 is decom4 pressed and the circlip 48 is unflexed, so that the plunger thereafter moves with the carrier and retracts its pointed end 78 from the hole in the seal 60 to permit carbon dioxide under pressure to flow through the aperture 58 into the recess 66, and from there to the expansion chamber 14 through the passage 70. Because of the narrowness of the passage 34 the flow of carbon dioxide from the expansion chamber 14 to the outlet chamber 10 is restricted so that a differential pressure is developed across carrier 40. With the continued flow of gas from the bulb 46 this pressure increases until the pressure in chamber 14 at first balances and then overcomes the combined effect of atmospheric pressure in chamber 16, the force of spring 68 and the gas pressure in the bulb 46 on the effective cross-sectional area of the point 78, to force carrier 40 and therefore plunger 44 to move to the right as viewed in the drawing until the point 78 of plunger 44 reduces or stops the flow of gas from the container 46. By these means the excessive flow of gas from the bulb 46 is prevented even while the main dispensing valve is open. When the pressure in chamber 14 drops below a certain value, and the main valve is still open, the forces urging the carrier 40 to the left overcome the bias exerted by chamber 14 and thus the point 78 is withdrawn from the seal 60 to admit more gas into recess 66 and the operating cycle is repeated. Of course, should the pressure in the outlet chamber 12, and therefore that above the liquid in the can, rise above a pre-set value, then the pressure-relief valve 76 opens to vent gas to the atmosphere.

When it is desired to stop dispensing beer from the can the handle controlling the main valve member 6 is operated so that member 6 is lowered and the cam track 24 indirectly forces the point 78 into sealing engagement with the seal 60, as described above.

It will thus be seen that the present invention provides a valve mechanism adapted automatically to stop or reduce the discharge of gas from a container of pressurized gas upon the occurrence of an excess rise of pressure in an expansion chamber forming part of the valve mechanism.

Although the illustrated valve mechanism is intended to be used with a specifically-designed dispensing device, it is conceivable that other forms of valve mechanisms of the present invention could be fitted to existing dispensers.