Abstract:
A liquid aerating apparatus—in combination with a cylinder containing gas under pressure ( 53 ); a cylinder holder ( 30 ) for retaining a pressure gas cylinder; an aerating ( 61 ) head for retaining a bottle ( 63 ) which contains a liquid to be aerated; an intermediate chamber ( 38 ), for receiving gas discharged from the cylinder ( 531 ); a cylinder valve ( 32 ) for normally preventing discharge from the cylinder into the chamber and permitting it when desired; valve actuating means ( 17′ ) which have an inactive position, in which they do not act on the cylinder valve, and an active position, in which they cause the cylinder valve to be opened and gas to be discharged from the cylinder to the intermediate chamber; gas conduit mans ( 20  connecting the intermediate chamber with the aerating head; and auxiliary valve means ( 39 ) for sealing off the intermediate chamber from the conduit means when the cylinder valve is not fully closed and the valve actuating means are in the inactive position. The auxiliary valve means comprises a control chamber ( 25 ), a plunger ( 42 ) sealing off the control chamber from the intermediate chamber when the valve actuating means are in the inactive position and permitting passage of gas from the intermediate chamber when the valve actuating means are in the active position.

Description:
This application is a continuation of international application number PCT/IL99/00508, filed Sep. 17, 1999. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to apparatus for aerating liquids, and in particular to portable machines for preparing aerated beverages and more particularly, to a safety device for such machines. 
     BACKGROUND OF THE INVENTION 
     Apparatus for preparing aerating beverages are very widely used in the home. Because of such widespread home use, safety requirements for such apparatus are particularly stringent. 
     In the aerating machine to which this invention refers, a bottle containing liquid to be aerated is loaded onto the machine and the gas is introduced into the machine and passed through the liquid contained in the bottle. The bottle is subsequently removed, when the aerating has been completed. 
     The gas used for aerating is supplied from a gas cylinder or balloon, which can be fitted onto the machine, on a part thereof hereinafter called “cylinder holder”, and replaced when it has become exhausted. A valve—hereinafter “the cylinder valve” is provided to control the flow of gas from the cylinder. Usually the cylinder is rechargeable and said valve is fitted onto its outlet, but may be part of the machine in the case of disposable cylinders. The bottle containing the liquid to be aerated, is fitted on another part of the machine, which will be called “the aerating head”. 
     Gas conduit means are provided in the machine for permitting gas to flow from the cylinder holder to the aerating head. When the cylinder valve is opened, gas passes into the cylinder holder and from it to the aerating head and through the liquid, generating an internal pressure within the machine and inside the bottle, which pressure is limited to a given maximum level by a valve, which will be called “the exhaust valve”. Said pressure is called hereinafter “the system pressure”. When the liquid aeration has been completed, which may be indicated by a sound produced by the exhaust valve when it opens to prevent the pressure from rising further, and the bottle is removed from the machine. In order to remove the bottle, it is tilted, and this causes a lever, hereinafter called “the tilting lever” to be tilted as well. Tilting the tilting lever causes a valve to be opened and to vent the pressure within the machine to the atmosphere. 
     A typical way of operating the cylinder valve consists in actuating, e.g., by means of a lever—hereinafter “the actuating lever”—a plunger which is in contact or in abutting relationship with a pin of the valve and, when actuated, displaces the valve pin, against the reaction of valve spring, so that it becomes detached from its seat and allows gas to flow between pin and seat. When the actuating lever is released, the reaction of the valve spring returns the valve pin to its closing position in its seat, and the plunger returns to its non-actuated position. The flow of gas from the gas cylinder to the machine and then to the bottle ceases. Another spring—“the actuating lever spring”—returns the actuating lever to its inactive position. 
     A aerating apparatus of this kind is described in European Patent No. 472.995, the entire contents of which are incorporated herein by reference. This invention is not limited to its application to the apparatus of EP 472.995, since it may be usefully applied to other liquid aerating apparatus. However, it will be described, by way of example and by way of preferred application, with reference to the said European patent. 
     FIG. 1 represents the portion of the apparatus of the said European patent on which the gas cylinder is mounted, only the top portion of the gas cylinder being shown. Numeral  10  designates a cylinder holder. Numeral  11  designates gas cylinder, on the neck of which the body  12  of a cylinder valve is mounted, e.g. by screwing. The gas cylinder is fitted onto the cylinder holder  10 , e.g. by screwing said valve body onto said cylinder holder. The valve body  12  has a valve chamber which houses spring  14 . A valve pin  15 , having a gasket  16 , is urged by spring  14  against a seat formed in said valve body, which is provided with a bore through which a projection of the pin passes. The cylinder holder  10  is provided with an actuating lever  13 , hingedly connected thereto at  18 , and which can be manually depressed and is urged to its normal, inoperative position by an actuating lever spring  70 ′. When depressed, it bears upon a plunger  19  slidable in the cylinder holder and depresses it. The lowermost end of plunger  19  contacts said valve pin  15 . Therefore, when lever  13  is depressed, said plunger causes said pin to be depressed, compressing spring  14  and leaving a space between the pin and its seat, through which gas can pass from the cylinder to a chamber  17  defined by inner surfaces of the cylinder holder and by the top surface of the cylinder valve, and therefrom to conduit  20 , only partially shown, from which the gas passes to the aerating head (not shown in FIG. 1) on which is mounted the bottle containing the liquid to be aerated. When lever  13  is released by the operator—as it may be released several times, and finally, when the escape of gas through the exhaust valve (not shown) indicates that the maximum pressure allowable within the machine has been reached—spring  14  causes valve pin  15  to rise and to close the cylinder valve, thus terminating the flow of gas from the cylinder to the bottle through conduit  20 . 
     However, should foreign material become trapped between valve pin  15  and its seating when the pin is depressed, this foreign material will prevent the pin from seating when lever  13  is released so that gas continues to flow from the gas cylinder to chamber  17  to the liquid containing bottle and/or to be discharged through the exhaust valve. While the machine is designed so that this has no harmful consequences, the user may become aware of the constant flow of gas and take some action, which action may initiate a serious malfunction of the machine and cause inconvenience to the user. 
     It will be understood that the aforesaid possible drawbacks are not limited to the device of European Patent 472.995, but are common to any liquid aerating apparatus in which the flow gas from a pressure gas cylinder to the apparatus and to the bottle containing the liquid is controlled by a valve that is opened by hand-actuating a mechanical element, such as a lever or the like. In any such apparatus, the possibility of the malfunction hereinbefore described exists and this invention is applicable to it. 
     Accordingly, it is a purpose of this invention to eliminate the aforesaid drawbacks from liquid aerating apparatus. 
     More specifically, it is an object of this invention to stop the flow of gas from the gas cylinder or balloon, whenever the user wishes to stop it, regardless of possible malfunctions of the valve which controls the outlet of said cylinder. 
     It is another purpose of this invention to provide, in a liquid aerating apparatus, in which a hand-operated mechanism is used to open the cylinder valve, to provide additional valve means, viz. means for automatically stopping the flow of gas from the gas cylinder to the aerating head and to the liquid containing bottle, if the cylinder valve has a malfunction. 
     It is a further purpose of this invention to assure that, should a cylinder valve pin be prevented from closing, due to wear or damage or for any reason, the flow of gas to the carbonating system is still prevented and further operation of the pin depressing means is inhibited or at least made difficult. 
     Other purposes of this invention will appear as the description proceeds. 
     SUMMARY OF THE INVENTION 
     The invention provides safety means for a liquid aerating apparatus, which apparatus comprises a cylinder holder for retaining a pressure gas cylinder, and an aerating head for retaining a bottle which contains a liquid to be aerated. 
     When the gas cylinder is mounted on the cylinder holder, an intermediate chamber is defined in said cylinder holder or between the same and the gas cylinder, for receiving gas discharged from said cylinder. A cylinder valve is provided for normally preventing discharge from said cylinder into said chamber and permitting it only when desired. Said cylinder valve may be part of the cylinder holder or may be mounted on the cylinder, depending on the type of cylinder used. In the latter case, the valve may be, e.g., screwed onto the neck of said cylinder, so that the used gas cylinder can be removed together with its valve from the cylinder holder, and substituted with a fully charged cylinder. However, the invention is equally applicable to apparatus in which the cylinder valve is fixed to the cylinder holder and the cylinder itself is, for example, disposable. In any case, when the cylinder valve is open, gas is discharged from the cylinder into the intermediate chamber. Conduit means are provided connecting said intermediate chamber to the aerating head and permitting gas to flow therethrough and, from the aerating head, to the bottle mounted thereon. Exhaust valve means are provided for limiting the pressure in the intermediate chamber, in the gas conduit means and in the aerating head to a predetermined maximum value. Since the aerating head and the exhaust valve means are not part of this invention, they will not be described herein in any detail. 
     Finally, valve actuating, kinematic means are provided which have an inactive and an active position. In the inactive position, they do not act on the cylinder valve, which remains closed. In the active position, they cause the cylinder valve to be opened and gas to be discharged from the cylinder to the intermediate chamber, They preferably comprise a lever and a kinematic connection whereby, when the lever is manually depressed, the cylinder valve poppet is also depressed to open said valve against the elastic reaction of elastic means, such as a helical spring and internal gas pressure. The aforesaid combination of means is part of the prior art, and is described, in a particularly advantageous form thereof, in European Patent 472.995. 
     According to this invention, safety means, which comprises essentially auxiliary valve means, is provided for sealing the intermediate chamber, into which gas is discharged from the gas cylinder, from the conduit means leading to the aerating head, when: a) the cylinder valve is at least partially open and permits gas to escape or leak from the gas cylinder into the intermediate chamber, and b), concurrently, the valve actuating means are in the inactive position, in which they are incapable of displacing any parts of the cylinder valve. Therefore, the intermediate chamber is only sealed when the cylinder valve is held open or partially open by foreign material, and not when it is held open by plunger  19  through pin  15  (see FIG.  1 ). 
     Said auxiliary valve means, interposed between the gas cylinder valve and the bottle containing the liquid to be aerated, comprise an inner chamber, apertures for permitting gas to pass through said chamber so as to flow from said gas cylinder valve to said bottle and means for sealing said apertures to prevent said gas flow unless said sealing means are inactivated by kinematic means. Preferably, the sealing means comprise a plunger having a first and a second surface exposed to the pressure in the inner chamber, said first surface having a larger area than said second surface, whereby to generate a pressure force actuating said plunger to seal the apertures of said inner chamber of the auxiliary valve. 
     In an embodiment of the invention, said auxiliary valve means comprises a control chamber, having a first aperture in communication with the intermediate chamber and a second aperture in communication with conduit means for leading the gas from said control chamber to the aerating head, plunger means for normally concurrently sealing said apertures when the cylinder valve is closed and the valve actuating means are in the inactive position and concurrently freeing them when the valve actuating means are in the active position, said plunger means having such surface areas exposed to the gas pressure in the intermediate chamber that said pressure generates a force displacing said plunger means concurrently to seal said apertures of said control chamber when the cylinder valve is not fully closed and the valve actuating means are in the inactive position 
     In a particularly preferred embodiment of the invention, the cylinder valve comprises a valve housing defining a valve chamber having an inlet communicating with the gas cylinder outlet and an outlet to an intermediate chamber; a poppet which has a pin slidable in said valve chamber outlet, a piston housed in said valve chamber and solid with it or attached to said pin, a seat projection in said valve housing about said outlet to the intermediate chamber, which projection can be engaged by said poppet piston in a gas-tight manner for preventing the discharge of gas from the valve chamber into the intermediate chamber, and elastic means, in general a helical spring, for urging said poppet body so to engage said seat projections 
     In said embodiment, the auxiliary valve means comprise a control housing which is housed in the cylinder holder, constitutes the upper boundary of said intermediate chamber, has top, bottom and peripheral walls and defines a control chamber, said top and bottom walls having each an aperture and said peripheral wall having an outer surface spaced from the inner surfaces of the cylinder holder to define a gas passage communicating with the conduit that leads the gas to the aerating head, a seat projection being defined in the lower surface of said bottom wall about said top wall aperture. A plunger is slidable in the cylinder holder and the control housing from an uppermost to a lowermost position, and comprises, from top to bottom, a stem passing through said aperture of said control housing top wall, a piston housed in said control chamber, a shank having a cross-section substantially smaller than that of said plunger stem and also housed in said control chamber, and a head slidable to seal, with the help of sealing gasket means, or free said aperture of said control chamber bottom wall. When said plunger is in its uppermost position, the plunger piston tightly engages said seat projection of said control housing and said plunger head seals said aperture of said control housing bottom wall so that said control chamber is tightly sealed. When said plunger is brought to its lowermost position by manually depressing an actuating lever, the plunger piston ceases to engage said seat projection of said control housing and said plunger head is displaced to below said aperture of said control chamber bottom wall and engages said poppet pin so as to disengage said poppet piston from said seat projection of said valve housing against the reaction of the aforesaid elastic means, whereby gas can freely flow from the gas cylinder to the valve chamber, from this latter to the intermediate chamber, from this latter to the control chamber, and from this latter to a gas passage communicating with the conduit that leads the gas to the aerating head. 
     In this type of apparatus, when the lever is released by the operator and is urged back by the gas pressure in the control chamber, the spring of the cylinder valve urges the poppet piston back into engagement with its seat projection, and the poppet pin, engaging the control plunger head, returns the plunger to its original position. The actuating lever is returned to its final, inactive position, by spring means, leaving a gap between it and the plunger  19 . However, if the cylinder valve malfunctions for any reason, and the poppet piston is not returned to its engagement with its seat projection, or is not fully returned to it, the cylinder valve does not fully close and gas continues to be discharged into the intermediate chamber. Pressure is created in said chamber and in the control chamber and generates an upwardly thrust on the lower face of the plunger piston and a downwardly thrust on its upper face. However, the area of the lower face that is exposed to the pressure is larger than the corresponding area of the upper face, because the plunger shank has a smaller cross-section than the plunger stem. Therefore the pressure displaces the plunger to its uppermost position, wherein it seals off the control chamber and the gas cannot pass from it to the conduit to the aerating head. 
     In an apparatus comprising the invention, if the cylinder valve malfunctions and the gasket means, which help to seal the aforesaid aperture of said control chamber bottom wall, is damaged, and gas leakage occurs, the auxiliary valve seals the intermediate chamber off from the conduit means to the aerating head, and the pressure is not discharged from the intermediate chamber when the bottle is removed from the machine, although it is discharged from the aerating head and the aforesaid conduit means. When a fresh bottle is fitted onto the aerating head, the operator will be able to repeat the aerating operation, but will have to overcome the force exerted on the valve poppet by the pressure in the intermediate chamber and therefore will have to make a stronger effort to operate the valve actuating lever. 
     The safety means, and particularly the auxiliary valve hereinbefore defined, while described in connection with an apparatus as described in European Patent 472.995, are applicable in general to any liquid aerating apparatus comprising a gas pressure cylinder and a bottle containing the liquid to be aerated. The invention, therefore, generally provides safety means comprising an auxiliary valve, which comprises an inner chamber, apertures for permitting gas to pass through said chamber so as to flow from said gas cylinder valve to said bottle and means for sealing said apertures to prevent said gas flow unless said sealing means are inactivated by kinematic means. In a preferred embodiment, the sealing means comprise a plunger having a first and a second surface exposed to the pressure in the inner chamber, said first surface having a larger area than said second surface, whereby to generate a pressure force actuating said plunger to seal the apertures of said inner chamber of the auxiliary valve. The difference between the areas of the first and of the second surface exposed to the pressure in the inner chamber, is sufficient to generate the pressure force actuating the plunger to seal the apertures of said inner chamber of the auxiliary valve whenever the gas cylinder valve is not fully closed. The auxiliary valve is preferably located above the gas cylinder valve and the first and second plunger surfaces are the lower and the upper surface respectively. In a preferred embodiment, said auxiliary valve comprises an inner chamber, apertures for permitting gas to pass through said chamber so as to flow from said gas cylinder valve to said bottle and means for sealing said apertures to prevent said gas flow unless said sealing means are prevented from sealing said apertures by kinematic means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 represents a cylinder holder according to the prior art and, more specifically, according to the cited EPA 472.995, the gas cylinder being only fragmentarily shown; 
     FIGS. 2 and 3 are cross-sections of the valve and auxiliary valve according to an embodiment of the invention, showing them in two different operative conditions, the cylinder holder and the gas cylinder being only fragmentary and schematically shown; 
     FIG. 4 is a vertical view of a liquid aerating apparatus according to an embodiment of the invention; 
     FIGS. 5 and 6 are cross-sections of the valve and auxiliary valve according to an alternative embodiment of the invention, showing them in two different operative conditions analogously to FIGS. 2 and 3; and 
     FIG. 7 illustrates in vertical view a plunger which is a component of the embodiment of FIGS.  5  and  6   
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The prior art cylinder holder of FIG. 1 has been described hereinbefore. It should be emphasized, once again, that this is only a device to which the invention is preferably applied, but that any liquid aerating device, in which gas discharged from a gas cylinder flows into an intermediate chamber and thence through conduit means to the liquid-containing bottle, and which is provided with means for opening the gas cylinder valve to admit gas to the intermediate chamber, can be advantageously supplied with the safety means according to the invention. 
     FIG. 2 illustrates a safety device, specifically an auxiliary valve, according to the invention, and the parts of the liquid aerating machine directly cooperating with it, in the inactive condition, viz. when the machine is not being used and liquid is not being aerated. Numeral  21  generally designates a cylinder holder which is only partially and schematically shown. Numeral  20  schematically designates the initial portion of the gas conduit connecting the cylinder holder to the aerating head. This latter, as well as the remaining part of the conduit, is not illustrated, since it may be of any desired kind, particularly such as is described in EP 472.995, with the only condition that it comprise an exhaust valve for discharging pressure from the aerating head and the remaining part of the apparatus when a) a predetermined maximum pressure has been reached in the aerating operation, and/or b) the bottle is removed from the machine. 
     As seen in FIG. 2, a guide cylinder  23  is defined at the top of the cylinder holder  21 . A plunger generally indicated at  22  comprises a stem  24 , a piston  39  and a head  42 . Plunger stem  24  is slidable in said guide cylinder  23 , generally in a substantially vertical direction. A gasket  40 , which is an “O” ring, seals the clearance between said plunger stem and said guide cylinder. Plunger stem  24  is solid with or connected to the plunger piston  39 , which is solid with or connected to a shank  41 , and this latter is connected to the plunger head  42 . A control housing  29  has a top wall  43 , a bottom wall  44  and a peripheral wall  44 . Top wall  43  has an aperture  46  through which plunger stem  24  passes, and is provided in its lower surface, about said aperture, with downwardly projection  47  against which plunger piston  39  bears, sealing aperture  46 , when the plunger is in its uppermost position. Control housing  29  defines an internal control chamber  25 . A peripheral gap  26  between the outer surfaces of the control housing  29  and the inner surfaces of the cylinder holder  21  places chamber  25  in communication with conduit  20 , only partially shown, from which the gas passes to the bottle containing the liquid to be aerated. Shank  41  ends with a head  42 , which is slidable in a generally cylindrical opening  48  of the bottom wall  45  of the chamber housing. An annular recess in said opening  48  houses a gasket  49 , which is an “O” ring and seals said opening  48  when said plunger head 42 is located within it, viz. in the uppermost position of the plunger. 
     The head of the cylinder valve is generally indicated at  30 . It defines a valve chamber  31 . In said chamber is housed a valve poppet  32 , which comprises a poppet pin  33  and a poppet piston  35 , provided with an upper layer  36  of gasket material, which is urged by a spring  34  against projection  50  disposed about an outlet  51  of said chamber  31  and constituting a seat for the valve poppet. When the cylinder valve is closed, said gasket layer  36  is pressed by spring  34  against said projection  50  and seals said outlet  51 , thereby sealing the valve chamber  31  from an intermediate chamber  38  defined between the top of cylinder valve  30  and the bottom of control housing  29 . Thus also the gas cylinder, fragmentarily indicated at  53 , which communicates with said valve chamber  31  through an inlet  54 , is sealed from said intermediate chamber  38 . 
     In FIGS. 2 and 3 only a fragment of the cylinder valve actuating means is shown. Said valve actuating means are assumed to be, in this embodiment, essentially the same as in the prior art machine of FIG. 1, viz. to comprise a lever hinged to the cylinder holder and having a portion adapted to engage and depress the valve control plunger  22 . The portion of said control means shown in FIGS. 2 and 3 is a fragment of actuating lever  13  (see FIG.  1 ), which portion is indicated by numeral  17 ′. When lever  13  is actuated, portion  17 ′ thereof engages plunger stem  24  and depresses the plunger  22 . Plunger head  42  is displaced to below opening  48  of the control chamber, and contacts and depresses poppet pin  33  and poppet  32  against the reaction of spring  34  and internal gas pressure. Poppet piston  35 - 36  becomes detached from projection  50  and therefore allows gas to escape from the gas cylinder and valve chamber  31  into intermediate chamber  38 . This condition is shown in FIG.  3 . It is seen that piston  39  no longer engages projection  47  and has freed the aperture  46  of wall  43 . Thus the auxiliary valve has opened, and gas can flow from intermediate chamber  38  into control chamber  25 , therefrom, through peripheral gap  26 , into conduit  20 , and finally to the bottle containing the water to be carbonated. 
     When the operator releases the lever that is part of the kinematic system which actuates the cylinder valve, this latter will normally close the cylinder outlet and gas will no longer escape from the cylinder. The gas pressure urges the valve poppet to its closing position. Then the gas pressure retained in the intermediate chamber  38  and in the control chamber  25  by the plunger stem  24  and the gasket seal  49  pushes the plunger to its uppermost, sealing position. 
     However, if the cylinder valve malfunctions, poppet  32  will not have risen to its original position, and therefore gas continues to escape into chamber  38 . Therefore gas pressure exists in intermediate chamber  38 , in control chamber  25 , in annular space  26  and in conduit  20  and other parts of the machine. Since the cross-sectional area of the bottom of piston  39 , on which said pressure generates an upwardly thrust, is larger than the free area of its top, on which said pressure generates an opposite thrust, a differential thrust is exerted by the gas in an upwardly direction and urges the entire plunger  22  to its uppermost position, shown in FIG. 2, in which apertures  46  and  48  are closed by plunger piston  39  and plunger head  42  respectively, control chamber  25  is sealed off, and gas can no longer escape from the gas cylinder to the bottle through peripheral gap  26  and conduit  20 . The same pressure as in the gas cylinder, e.g. about 50 bar, is created in the intermediate chamber  38 . The control chamber  25  is at the same pressure as annular space  26 , conduit  20  and other parts of the machine. 
     If the valve poppet  32  is held open, the cylinder pressure (which may be, e.g. 50 bar) acts over the lower surface of plunger head  42  in an upward direction, while the system pressure (which may be e.g. 8 bar) acts over the upper surface of piston  39  but is balanced by the same pressure acting over its lower surface, until the system pressure has been released. Thereafter the operator, in order to open the cylinder valve, would have to overcome a force equal to the product of the system pressure by the upper area of piston  39  plus the product of the cylinder pressure by the area of head  42 . 
     When the machine is in the condition of FIG. 3, the aerating operation can be repeated, but the operator will find it difficult since he has to overcome the thrust due to the high pressure in intermediate chamber  38 . If the operator wishes to remove the gas cylinder, the cylinder valve head will become detached from the washer seal  190  (corresponding to  90  in FIG. 1) and gas can flow from chamber  38  (see FIG. 3) through the annular space between threads of cylinder holder  21  and valve body  30 . Pressure therefore will be reduced to atmospheric pressure, the gas cylinder can be safely removed and substituted with a fresh one, and thereafter the machine will operate in a normal way. 
     FIG. 4 schematically illustrates a liquid aerating apparatus comprising the safety means of the invention. Numeral  60  indicates the apparatus main body, on which is hinged at  62 ′ an aerating head  61 ′. Bottle  63 ′ is mounted, e.g. threaded, on said head  61 ′. Tube  64 ′ is connected to the previously described gas conduit  20  by which the gas is led into the bottle. An exhaust valve, of any suitable kind and e.g. as described in European patent 472.995, is provided at  65 ′, for discharging pressure from the bottle, the gas conduit means and the intermediate chamber. Means are provided for actuating the exhaust valve to release pressure when the bottle is swung about hinge  62 ′ beyond a certain angle, as occurs in any case when the bottle is removed from the aerating head. Said means, as well as other safety valve means that can be provided, are not described, as they may be of any kind known in the art, and e.g. as described in European patent 472.995. The cylinder holder and cooperating parts are as illustrated in FIGS. 2 and 3 and described hereinbefore. 
     In order further to illustrate the invention, a summary is given hereinafter of the sequences of operations carried out when operating a machine according to the aforesaid European Patent 473.995 and when operating a machine according to this invention. The machine according to the aforesaid European Patent 473.995 comprises three valves: EXHAUST, VENT and SAFETY valve. The following operational stages occur when the liquid contained in a bottle, which has been fitted into the machine, is carbonated, viz. be mixed with a gas that is in general carbon dioxide. 
     When the actuating lever is depressed by the user, the following operational stages occur: 
     a. The cylinder valve is opened to admit gas into the bottle. 
     b. System reaches pressure—EXHAUST valve buzzes. 
     c. Tilt the bottle thereby operating a tilt lever. 
     d. VENT valve releases pressure after a few degrees movement of the tilt lever and stays open until the tilt lever returns to the carbonating position. 
     e. One valve is now open. 
     f. Move tilt lever more. 
     g. Vent pin opens EXHAUST valve by pushing the EXHAUST valve poppet off its seating and any remaining pressure is released, 
     h. Two valves now open. 
     i. Move tilt lever more. 
     j. Safety pin opens SAFETY valve by pushing the valve poppet off its seating, and any remaining pressure is released. 
     k. All three valves are open. 
     When the actuating lever is released by the user, the following operational stages occur: 
     a. The gas pressure, combined with the pressure exerted by the cylinder valve spring ( 14  in FIG.  1 ), urges the valve poppet pin ( 15  in FIG. 1) to close. 
     b. This movement pushes the plunger ( 19  in FIG. 1) upwards, which pushes the actuating lever ( 13  in FIG. 1) upwards. 
     c. The valve poppet pin closes; no farther upward movement is possible for this part. 
     d. The plunger is urged upwards due to gas pressure acting over the area which is sealed from the atmosphere, which pushes actuating lever upwards. 
     e. The plunger comes up against a mechanical stop;  110  further upward movement is possible for this part. 
     f. The actuating lever continues to move upwards to its inactive position under the action of the lever spring ( 70 ′, in FIG.  1 ). 
     The machine according to the embodiment of the invention illustrated herein operates through the following operational stages, described with reference to FIG. 3, unless otherwise specified 
     Normal Operation 
     a. Press lever down, gas is released from cylinder (wherein the pressure is e.g. 50 bar) into intermediate chamber  38  to control chamber  25 , to aperture  46 , to conduit  20 , and from it to the aerating head (at a lower pressure of e.g. 8 bar). 
     b. Release actuating lever  13 . 
     c. The cylinder valve closes and chambers  38  and  25 , aperture  46  and conduit  20  are isolated from cylinder pressure and all the system goes to a lower pressure, e.g. 8 bar, which is the system pressure. 
     d. Release actuating lever  18   
     e. Plunger head  42  seals the outlet  48  of the intermediate chamber  38  and isolates it from chamber  25 , aperture  46 , and conduit  20 . Chamber  38  maintains the system pressure. 
     f. Release actuating lever  13 . 
     g. Piston  39  makes sealing contact with projection  47  and the upward movement of plunger  22  is halted; said piston also isolates (though not quite perfectly) control chamber  25  from peripheral gap  26  and conduit  20 . Chamber  25  maintains the system pressure (e.g. 8 bar). 
     h. Release actuating lever  13 ; spring  70 ′ (see FIG. 1; not visible in FIG. 3) returns lever  13  to its inactive position. 
     i. Plunger  22  is now subjected to an upward force, due to said system pressure (e.g. 8 bar) acting over the area defined by “O” ring  40 . 
     j. Release pressure in system by tilting the bottle, thereby operating the tilting lever. 
     The release of the actuating lever is mentioned in four of the above steps. In actual use, however, said release is a continuous movement. 
     k. The pressure in gap  26  and conduit  20  goes to atmospheric pressure. 
     l. Control chamber  25  maintains the system pressure (e.g. 8 bar) or may decay to atmospheric pressure as its seal is not perfect (see stage g). 
     m. Intermediate chamber  38  maintains the system pressure (e.g. 8 bar). 
     n. The upward force on plunger  22  due to pressure is still the previous system pressure (e.g. 8 bar) acting on the area defined by “O” ring  40  in the bore of guide cylinder  23  (see FIG. 2) as plunger head  42  is of smaller diameter than “O” ring  40 . This is the case, regardless of whether control chamber  25  maintains the previous system pressure or leaks to the atmosphere. 
     o. Make a new bottle of soda. 
     p. Press lever down against the said previous system pressure (e.g. 8 bar) acting over the “O” ring  40  area, this force being less than the force required to overcome the opening of the valve poppet against the gas pressure of 50 bar. Therefore the operation appears normal, and this sequence is repeated 
     Abnormal Operation (Scenario 1) 
     1. Press actuating lever  13  down, gas is released from cylinder (at pressure of e.g. 50 bar) into intermediate chamber  38  and from it to control chamber  25 , to gap  26 , and to conduit  20  and from it to the aerating head (at pressure of e.g. say 8 bar). 
     2. Release actuating lever  13 . 
     3. Valve poppet  32  does not seal and gas continues to be released into chambers  38  and  25 , to gap  26  and to conduit  20 . 
     4. Release actuating lever  13 . 
     5. Head  42  seals perfectly and isolates chamber  38  from chamber  25 , gap  26  and conduit  20 . Chamber  38  maintains the cylinder pressure (e.g. 50 bar). 
     6. Release actuating lever  13 . 
     7. Piston  39  seals on projection  47  and the upward movement of plunger is halted; the piston further isolates ((though not quite perfectly) chamber  25  from gap  26  and conduit  20 . Chamber  25  maintains the system pressure (e.g. 8 bar). 
     8. Release actuating lever  13 ; spring  70 ′ returns the lever to inactive position. 
     9. The upward force on plunger  22 , due to pressure, is the cylinder pressure (e.g. 50 bar), acting over the area defined by “O” ring  49  sealing on plunger head  42 . 
     10. Release pressure in system by tilting the bottle, whereby the tilting lever is tilted. 
     11. The system goes to atmospheric pressure and so do gap  26  and conduit  20 . 
     12. Control chamber  25  maintains the previous system pressure (e.g. 8 bar) or may decay to atmospheric pressure as it is not perfectly sealed. 
     13. Chamber  38  maintains the cylinder pressure (e.g. 50 bar). 
     14. The upward force on plunger due to pressure is still that generated by the cylinder pressure (e.g., 50 bar), acting on the area defined by “O” ring  49 . This is greater if chamber  25  maintains the previous system pressure and does not leak, or unchanged if it leaks back to atmosphere. 
     15. Make a new bottle of soda. 
     16. Press actuating lever  13  down against a pressure of 50 bar acting over the “O” ring  49  area, this force being greater than the force required to overcome the opening of the valve poppet against the gas pressure of 50 bar. The operation may appear abnormal, and the extra force required may be noticed. If not, then the sequence will be repeated until the cylinder of gas is empty, and the customer will not be aware that there was ever a problem. If the customer becomes aware that he has to exert an abnormally high force to press the actuating lever, then the cylinder can be removed and gas from intermediate chamber  88  will vent down the cylinder threads  100  (see FIG. 1) and the cylinder will be removed safely. 
     Abnormal Operation (Scenario 2) 
     1. Press lever down; gas is released from the gas cylinder, at cylinder pressure (e.g. 50 bar) into intermediate chamber  38  to control chamber  25 , to peripheral gap  26 , to conduit  20 , and from it to the aerating head, at system pressure (e.g. 8 bar). 
     2. Release actuating lever  13 . 
     3. Valve poppet  32  does not seal and gas continues to be released into chambers  38  and  25 , gap  26  and conduit  20 . 
     4. Release actuating lever  13 . 
     5. Head  42  does not seal as “O” ring is damaged, and therefore does not isolate chamber  38  from chamber  25 , gap  26 , and conduit  20 . Gas continues to flow through the system. 
     6. Release actuating lever  13 . 
     7. Piston  39  seals on projection  47  and the upward movement of plunger is halted; the seal isolates chambers  38  and  25  from gap  26  and conduit  20 . Chambers  38  and  25  maintain the cylinder pressure, and seal well because of the cylinder pressure is high (e.g. 50 bar). 
     8. Release actuating lever  13 ; spring  70 ′ returns the lever to inactive position. 
     9. The upward force on the plunger is now that generated by the cylinder pressure acting over the internal area defined by the projection  47  sealingly engaged by piston  89 . 
     10. Release pressure in system by tilting the tilting lever. 
     11. The system goes to atmospheric pressure and so do gap  26  and conduit  20 . 
     12. Chambers  38  and  25  maintains the cylinder pressure. 
     13. The upward force on plunger due to pressure is still that generated by the cylinder pressure acting over the internal area defined by the projection  47  sealingly engaged by piston  39 . 
     14. Make a new bottle of soda. 
     15. Press the actuating lever  13  down against the cylinder pressure (e.g. 50 bar), if possible. The force required to do this is abnormally high, therefore the operation will appear abnormal (in the event that the user continues to operate the machine, the above stages will be repeated until the cylinder of gas is empty.) 
     It will be understood that the plunger head  42 , which isolates the intermediate chamber from the control chamber, can be considered the primary safety device, because in principle it can provide the required safety. The piston  39  is a secondary safety device which operates if the primary device fails. It could work alone, but, if so, the user would normally have to press the actuating lever harder, which is not desirable. The primary safety device is designed to become effective before the secondary safety device, in order to ensure that under both normal and abnormal use (Scenario 1) the customer does not perceive a problem. 
     FIGS. 5 and 6 illustrate a second embodiment of the invention, which operates essentially in the same way as that of FIGS. 2 and 3, but is structurally modified with respect to this latter 
     In FIG. 5, a guide attachment  61  is shown, mounted defined at the top of the cylinder holder, which is not shown. Attachment  61  has an inner cylindrical seat  63  and, in this embodiment, is provided with a pin connection  80  to operating lever  81  held in inoperative position by a spring  81 ″. A plunger, generally indicated at  62 , comprises a stem  64 , a piston  79  and a head  72 . Plunger stem  64  is slidable in said cylindrical seat  63 , generally in a substantially vertical direction. A gasket  70 , which is an “O” ring, seals the clearance between said plunger stem and said guide cylinder. Plunger stem  64  is solid with or connected to the plunger piston  79 , which is solid with or connected to a shank  71 , and this latter is connected to the plunger head  72 . In this embodiment, shank  71  and head  72  constitute a single piece. A control housing  89  has a top wall  73  and a peripheral wall  75 . and is completed by a bottom plate  74 . An O-ring  179  provides a tight seal between the plunger and the bottom plate  74 . 
     Plunger and control housing are illustrated at a great scale in FIG.  7 . It is seen that the plunger shank  71  has a central slit  82 . 
     Top wall  73  has an aperture  76  through which plunger stem  64  passes, and is provided in its lower surface, about said aperture, with downwardly projection  77  against which plunger piston  79  bears, sealing aperture  76  when the plunger is in its uppermost position. Control housing  69  defines an internal control chamber  65 . 
     The cylinder valve, generally indicated at  84 , comprise a poppet  85  provided with a gasket layer on its upper surface. The poppet is urged by the cylinder gas pressure against projection  86  disposed about the lowermost periphery of an outlet  87  of said valve and constituting a seat for the valve poppet. Similarly to what occurs in the embodiment of FIGS. 2 and 3, means, e.g. elastic means, are preferably provided normally to urge poppet  85  against seat  86 , regardless of the presence or not of pressure in the cylinder. When the cylinder valve is closed, said gasket layer is pressed against said projection  86  and seals said outlet  87 , thereby sealing the gas cylinder, fragmentarily indicated at  88 , 
     Lever  81 , hinged to the attachment  61 , has a portion adapted to engage and depress the plunger  62 . When lever  81  is actuated, portion  81 ′ thereof engages the plunger stem and depresses it. Plunger head  72  is displaced to below O-ring  179  and contacts and depresses poppet pin  83  (corresponding to  33  in FIG. 3) and valve poppet  85  against the internal gas pressure. The gasket layer of the poppet becomes detached from projection  86  and therefore allows gas to escape from the gas cylinder and the valve, between the poppet and its seat, into an intermediate chamber  78  formed between the top of cylinder valve  84 , viz. said poppet and its seat, and bottom plate  74 . This condition is shown in FIG.  6 . Thus gas can flow from said intermediate chamber through the slit  82  of the plunger, and therefrom into control chamber  65  and through opening  20 , which leads to the conduit connected to the bottle to be carbonated. 
     When the operator releases the actuating lever, the gas pressure urges the valve poppet to its closing position and gas will no longer escape from the cylinder. Then the gas pressure retained in the intermediate chamber  78  pushes the plunger to its uppermost, sealing position. 
     However, if the cylinder valve malfunctions, valve poppet  85  will not have risen to its original position, and therefore gas continues to escape into chamber  78  and from it to the internal control chamber  65 . Since the cross-sectional area of the bottom of piston  79 , on which said pressure generates an upwardly thrust, is larger than the free area of its top, on which said pressure generates an opposite thrust, a differential thrust is exerted by the gas in an upwardly direction and urges the entire plunger  62  to its uppermost position, shown in FIG. 5, in which internal, control chamber  65  is sealed off and gas can no longer escape from the gas cylinder to the bottle through slit  82  and port  20 . The same pressure as in the gas cylinder, e.g. about 50 bar, is created in the intermediate chamber  78 . The control chamber  65  is at the same pressure as the other parts of the machine. 
     If the valve poppet  85  is held open, the cylinder pressure (which may be, e.g. 50 bar) acts over the lower surface of plunger head  72  in an upward direction, while the system pressure (which may be e.g. 8 bar) acts over the upper surface of piston  79  but is balanced by the same pressure acting over its lower surface, until the system pressure has been released. Thereafter the operator, in order to open the cylinder valve, would have to overcome a force equal to the product of the system pressure by the upper area of piston  79  plus the product of the cylinder pressure by the area of head  72 . 
     As stated hereinbefore, the embodiment of FIGS. 5 and 6 is functionally equivalent to that of FIGS. 2 and 3 and constitutes an alternative constructional embodiment of the same invention. All the stages of normal and abnormal operation described hereinbefore apply equally to the embodiment of FIGS. 5 and 6.