Abstract:
A pressure capsule for a spray can includes a housing with a chamber disposed therein and a valve mounted within a wall of the housing, the valve is capable of being moved into an open and a closed position such that the valve is moved into the closed position when (1) the pressure capsule is placed in an atmospheric environment and (2) the pressure capsule is placed in a spray can and subjected to a pressure equal to or greater than the operating pressure of the spray can.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a pressure capsule as well as a spray can which utilizes such pressure capsule. 
     The present invention more especially relates to a pressure capsule which prior to or during the filling of a spray can or similar is installed in the latter and offers the possibility of possibly making use of, either compressed air, or an inert gas as means of propulsion for such spray can, all of which such that a spray can is obtained which has no detrimental effect on the environment and which furthermore has the possibility and the simplicity of operation which at this moment are only to be found with spray cans with the known harmful propellants. 
     1. Field of the Invention 
     From the Belgian Pat. No. 8801131 of applicant a pressure capsule is already known which principally consists of at least two chambers of which the first is intended to be filled with a fluid under relatively high pressure and of which the second is intended to be filled with a fluid up to a pressure almost equal to the over pressure which normally exists in a spray can and which is necessary for expelling a liquid; in the wall of the first chamber a valve; in the wall of the second chamber a membrane that can command the aforementioned valve; and a removable element that in its unremoved position holds the valve closed. 
     With this known pressure capsule the aforementioned removable element can directly or indirectly act on the valve in order to hold this closed and preferably consists of a material meltable by little heat, all of which such that, after the aforementioned removable element is removed, the aforementioned valve is so regulated by the membrane that fluid is released from the first chamber as long as the pressure in the vicinity of the pressure capsule decreases or at least is notably lower than the pressure in the second chamber of the pressure capsule. 
     Although this known pressure capsule works very efficiently the present invention relates to a pressure capsule which still shows considerable additional advantages. 
     SUMMARY OF THE INVENTION 
     A first advantage of the pressure capsule according to the invention is that no removable element is necessary so that heating of the spray can, with the intention of melting away the removable element, is no longer necessary. 
     Another advantage of the pressure capsule according to the invention is that in the spray can, after the pressure capsule is installed therein, a specific pre-pressure is provided, preferably at least the operating pressure of the spray can, through which the aforementioned pressure capsule can remain smaller because of the fact that less pressure fluid is necessary in the pressure capsule so that consequently the material costs are also lower. 
     Yet another advantage of the pressure capsule according to the invention is the very great safety of a spray can equipped with such pressure capsule since, with a possible tearing, leakage or similar of the spray can, the pressure capsule automatically closes, since at that moment the pressure around the pressure capsule drops. 
     Another advantage of the pressure capsule according to the invention is that it is no longer necessary, which is the case with a pressure capsule with removable element, during its manufacture, to determine the correct location of the small hole that the removable element must receive, since the opening or passage of the pressure capsule which is in contact with the environment can be provided in any manner and in any place, so that a difficult orientation operation can be omitted. 
     Another advantage still of the pressure capsule according to the invention is that the dimensions of the aforementioned opening or passage have no importance with regard to the operation of the pressure capsule. 
     Yet another advantage of the pressure capsule according to the invention is ultimately that it is extremely simple to realize, either as dual chamber pressure capsule, or as single chamber pressure capsule. 
     The pressure capsule according to the invention which shows the aforementioned and other advantages principally consists of at least one chamber which is intended to filled with fluid under relatively high pressure; in the wall of this chamber a valve; means which can command the valve; means which hold the valve in closed position when the pressure capsule is in an atmospheric environment, on the one hand, as well as when the pressure capsule is in an environment where the pressure is equal to or greater than the operating pressure in the spray can, in other words the pressure which is necessary for the expulsion of a liquid, on the other hand; whereby the rod of the valve is attached to a membrane in the chamber, respectively to a disk shaped extremity and whereby the space between the walls, respectively between the wall and the disk shaped extremity, is in continuous connection with the environment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to show better the characteristics according to the present invention, some preferred embodiments are described hereafter, as examples and without any restrictive character with reference to the enclosed drawings in which: 
     FIG. 1 shows a spray can in which a pressure capsule according to the invention is utilized; 
     FIG. 2 shows on larger scale a section of a pressure capsule according to the invention, more especially according to line II--II in FIG. 1; 
     FIG. 3 shows on larger scale the part that is indicated by F3 in FIG. 2; 
     FIGS. 4 and 5 are similar views to that from FIG. 3 but for two other characteristic positions; 
     FIGS. 6 and 7 show variants of FIG. 3; 
     FIG. 8 shows a practical embodiment of a pressure capsule according to the invention; 
     FIG. 9 shows a section according to line IX--IX in FIG. 8; 
     FIG. 10 shows another variant of a pressure capsule according to the invention 
     FIG. 11 shows a top view of FIG. 10; 
     FIG. 12 shows a second position of FIG. 10. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1 a classic spray can 1 is shown which is filled with a liquid 2 to be dispersed and in which a pressure capsule 3 according to the invention is installed. 
     The pressure capsule 3, as shown in FIG. 2, can be constructed in any manner by assembling various parts by screwing, welding or similar. For simplicity the pressure capsule in FIG. 2 is however shown as being of one unit. 
     The pressure capsule 3 in this embodiment principally consists of two chambers, respectively 4 and 5, of which the first chamber 4 is intended to be filled with a fluid under relatively high pressure and of which the second chamber 5 is intended to be filled with a fluid under a pressure which is equal or almost equal to the over pressure which is normally applied in a spray can 1. 
     A valve 7 is provided in the wall 6 of the first chamber, while in the second chamber 5 a wall 8 is installed which is provided with a membrane 9 that bears a rod 10 to which the valve 7 is attached. From the preceding it follows that the walls in which, on the one hand, the valve 7 and, on the other hand, the membrane 9 are installed, are located opposite each other whereby the space 11 between the walls 6 and 8 are directly connected to the vicinity of the pressure capsule 3, in this case via a small hole 12. 
     In the embodiment according to FIG. 2 the chambers 4 and 5 each show an opening, respectively 13, 14, which can be closed by suitable sealing means 15, 16. 
     The valve 7 is in this case formed by, on the one hand, the aforementioned rod 10 which is attached by one extremity to the membrane 9, whereby this rod passes through an opening in the wall 6 and underneath shows a peripheral groove 17, which for example is produced in a diabolo shape and, on the other hand, a sealing ring 18 which is installed in the aforementioned opening in the wall 6 and which functions as seat for the valve 7. 
     The inner diameter of the sealing ring 18, which is produced in an elastic material, for example rubber or similar, will preferably be somewhat smaller than the outer diameter of the rod 10 whereby the sealing ring 18 is placed in the aforementioned peripheral groove 17. 
     According to the invention, for example via the opening 13, the first chamber 4 is filled with a fluid under high pressure, for example of the order of 30 kg/cm 2 , such as compressed air or another gas, preferably, but not necessarily, an inert gas, after which the opening 13 is sealed off with suitable means, such as by gluing, by welding, by a screw plug or similar 15. 
     The chamber 5 is likewise filled via the opening 14 with compressed air or another fluid up to an over pressure which is approximately equal to the desired operating pressure in the spray can 1, whereby this operating pressure is for example of the order of 3 kg/cm 2 . Once at this pressure the chamber 5 will be sealed off by means 16, such as for example by gluing, by welding, by a screw plug or similar. 
     The pressure capsule 3 as described above can be utilized very advantageously in a spray can 1 filled with liquid 2 in order to supply the pressure medium, in this case air, that serves to remove the liquid 2 from the spray can 1 via an ascending tube 19 and controlled through a valve 21 operatable by means of a press button 20. 
     For this purpose the pressure capsule 3 is installed in the spray can 1, prior to, during or after the filling of the spray can 1 with liquid 2 and prior to the installation of the cover 22 with the ascending tube 19 and the valve 21, after which according to the invention the spray can 1, such as this is the case with traditional spray cans, is brought up to operating pressure, in other words up to a pressure which is equal to or is somewhat higher than the pressure in the chamber 5. 
     Because of this it is achieved that the membrane 9, under influence of the pressure in the space 23 above the liquid 2, on the one hand, and the small additional pressure of the fluid in the chamber 4 at the extremity of the rod 10, on the other hand, in FIG. 2 moves upwards through which the sealing element 10 moves out of the position as shown in FIG. 3 to the position as shown in FIG. 4, with as result that compressed air or similar escapes out of the chamber 4 through the opening 12 into the space 23, all of which such that the upward pressure P on the membrane 9 increases with ultimately as result that the membrane 9 is placed in the position as shown in FIG. 5, in other words in the position whereby the valve 7 in its second position works together with the sealing ring 18 so that removal of compressed air from chamber 4 towards the space 23 is stopped. 
     When at this time, through the depression of the press button 20, liquid 2 is dispersed under influence of the pressure of the fluid in the chamber 23, the pressure in the space 23 will decrease until an equilibrium is reached with the pressure in chamber 5 of the pressure capsule 3, through which the membrane moves downward and the valve 7 comes into the position of FIG. 4. 
     It is clear that at this time compressed air escapes out of chamber 4 towards the space 23 through which the pressure P on the membrane 9 again increases so that, when the force exerted under the membrane 9 becomes greater than the force above the membrane, the latter again moves upwards in order to close off the supply of compressed air from the chamber 4 towards the chamber 23, as shown in FIG. 5. 
     In FIG. 6 an embodiment variant is shown whereby the valve 7 is formed by sealing elements for example in the form of a frustum of a cone, respectively 24 and 25, which can alternatively close off the opening 26 in the wall 6. 
     An embodiment is shown in FIG. 7 whereby the valve 7 is formed by an oblique passage 27 which can move under or above the sealing ring 18 when the valve 7 is closed, and just at the height of the sealing ring 18 when the valve 7 is opened. 
     An embodiment is shown in schematic manner in FIGS. 8 and 9 whereby the lower chamber 4 consists of an upper part 28 and a lower part 29 which fit together suitably and are connected to each other by gluing, welding or similar 30 and whereby the upper chamber also consists of two parts, respectively 31 and 32, which are connected to each other in suitable manner by gluing or welding 33 with insertion of the wall 8 of the membrane 9. 
     In this embodiment the part 31 of the chamber 5 shows as it were four small legs 34 which underneath show an inwardly directed tooth shaped projection 35 which can work together, by clipping in, behind the edge 36 of the part 28 of the chamber 4. 
     In this case the opening 12 is formed between the aforementioned small legs 34. 
     It is clear that the pressure in the chamber 5 can be formed in whatever manner and need not necessarily be built up by means of a fluid. Indeed the pressure above the membrane 9 could also be formed by a suitable spring or similar for example an elastic material such as among others a small block of foam rubber 37. 
     Another embodiment variant is shown in FIG. 10 which is based on a single chamber pressure capsule. 
     With this only the chamber 4 is provided which as with the dual chamber pressure capsule described above is filled with a fluid under relatively high pressure. 
     In this case the membrane 9 is replaced by a stiff disk shaped extremity 38 of the rod 10, whereby between the wall 6 of the chamber 4 and the aforementioned extremity 38 an elastic element 39 is installed, foam material, with closed cells, whereby the elasticity of the element 39, which as it were is the so-called reference pressure (to be compared to the pressure in the space 5 in the embodiment according to FIG. 2) which is present in the cells, will be chosen or determined in relation to the operating pressure in the spray can 1. 
     In the embodiment according to FIG. 10 a small annular block of foam material 39 is provided in which at least one groove, passage or similar 40 is made, whereby this small block 39 is attached to, on the one hand, the wall 6 and, on the other hand, the disk shaped extremity 38, for example by gluing or another attachment. 
     The attachment of the small block 39 and the valve could for example also be effected by extending the housing of the pressure capsule to above the aforementioned extremity as is shown in dotted line in FIGS. 10 and 12, so that the upper position of the small block 39 is determined by the presence of the ring 41. 
     In FIG. 10 the position of the air pressure capsule is shown when this is in an atmospheric environment. The lower part of the valve 7 closed off the chamber 4 and ring 39 is in released position, whereby the pressure of the ring 39 or similar on the disk shaped extremity 38 is approximately equal to atmospheric pressure, whereby the pressure in the closed cells of the ring 39 amounts to one bar. 
     When the air pressure capsule according to FIG. 10 is inserted into a spray can 1 and the latter is brought up to operating pressure, the pressure exerted on the extremity 38 will be such that the seal 10 moves into the chamber 4 whereby the disk shaped extremity 38 presses on the spring, small block of foam material or similar 39 and brings this into the position as shown in FIG. 12, whereby the valve 7 is again closed off. 
     When now, through the spraying of the liquid, the pressure in the spray can 1 slowly decreases, the valve 7, respectively the rod 10 with the disk shaped extremity 38, will again move upwards under influence of the expansion effect of the small block or similar 39. Because of this an amount of compressed air can escape out of the chamber 4 along the valve 7 and arrive in the space 23 in the spray can 1 so that, just as with the preceding embodiment, the pressure in the space 23 again increases until the valve 7 again closes off the space 4. 
     It is clear that, through the correct choice of the material for the small block 39 or similar, on the one hand, and the surface area of the disk shaped extremity 38, on the other hand, the operating pressure in the space 23 of the spray can 1 can be determined. 
     The present invention is in no way restricted to the embodiments described as examples and shown in the attached drawings but a pressure capsule according to the invention can be implemented in all types of forms and dimensions without departing from the scope of the present invention.