EP0682640B1

EP0682640B1 - Double valve

Info

Publication number: EP0682640B1
Application number: EP95906832A
Authority: EP
Inventors: Per Kurt Augustinus; Ken Riis
Original assignee: Micro Matic AS
Current assignee: Micro Matic AS
Priority date: 1994-02-25
Filing date: 1995-02-24
Publication date: 1997-12-10
Anticipated expiration: 2015-02-24
Also published as: CZ287474B6; ES2110831T3; AU1755195A; DE69501181D1; DK172394B1; PL310972A1; DK23594A; DE69501181T2; CZ275295A3; PL177836B1; WO1995023112A1; ATE161002T1; EP0682640A1

Abstract

A double valve (1) is used for a container (4) of the type serving the purpose of distribution of a liquid, e.g. beer, which is stored in the container (4) under pressure of a gas, e.g. CO2. The valve (1) comprises a liquid passage (5); a gas passage (6); an elastomer valve ring (7) placed in the gas passage and being axially displaceable for closing the gas passage (6); an opening (10) formed in the valve ring (7) which opening forms the mouth of the liquid passage (5); a valve plug (11) placed in the liquid passage (5) and being axially displaceable serving the purpose of closing this mouth. In the valve ring (7) a reinforcement ring (19) has been inserted with an inside turning collar (21) having a number of incisions (23). At these incisions (23) there will be created weaker areas in the valve ring (7) which areas will be broken in such a way that there will be a free passage for the flow of the gas out to the open when the pressure in the container (4) by intensively heating of the gas during for instance a fire exceeds the acceptable limit for the container (4). In that case the double valve will work as an efficiently operating security valve.

Description

The invention relates to a double valve for a container of the type used for distribution of a liquid, e.g. beer, stored in the container under pressure of a gas, e.g. CO₂, whereby the valve defines an axis and comprises a central liquid passage; a ring formed gas passage defining a seat for a elastomere valve ring is arranged around the liquid passage; a reinforcement ring made of a strong and stiff material as e.g. steel and having a larger outer diameter than the inner diameter of said seat is inserted into the elastomere part of said valve ring; the valve ring is axially movable placed in the gas passage serving the purpose of closing said gas passage by, under influence of the gas pressure and the spring force from a pressure spring, being pressed into tight engagement with the seat of the gas passage; an opening formed in the valve ring is forming the mouth of the liquid passage; and a valve plug is axially displaceable placed in the liquid passage serving the purpose of closing the mouth by under influence of the load of the valve plug and the spring force from a second pressure spring being pressed into tight engagement with a seat formed in the opening of the valve ring.
Such containers are used especially for beer, cola and similar popular beverages. The numbers being in circulation are very high and the containers will often be situated in restaurants or similar establishments where many people will come and go.
The containers are normally without any danger to the surroundings. The working pressure is only a few bars, and the containers are dimensioned on the large side to be able to resist this pressure. If a container, however, is exposed to intense heat, which for instance might be the case when a building is burning, the pressure in the container might be so high, that the container will explode whereby persons, who might be nearby, could be hit and be seriously injured.
When these containers are used for foodstuffs they can hardly be supplied with special security valves to blow off too high a pressure. This is among other things due to the fact that an efficiently operating security valve is a rather complicated mechanism with components and inaccessible corners which are liable to withdraw the cleaning which the containers otherwise are subjected to. Therefore, there will always be a risk that such security valves might be hotbed of developing for example cultures of bacteria which might destroy or poison the beverages being stored in the container.
The double valves, which are mounted on the containers, have a construction which entails that the valves, without being dismounted, can be cleaned efficiently and safely in the same process as the container. The construction entails, however, at the same time, that the higher the pressure in the container rises, the tighter the valve will close. These conventional double valves are therefore not able to secure a container from exploding due to overpressure.
US Patent No. 4 159 102 discloses such a double valve. The valve ring of the double valve is reinforced by a metal insert. Due to the weakness of this insert the valve ring is able to be shot out of the valve seat by overpressure.
US Patent No. 4 509 663 discloses an improvement of the above named double valve. The improvement consists in that the metal insert now is made relatively strong. In this case the valve ring therefore cannot be shot out of the valve seat by overpressure. Said US Patent is silent about the relation between the dimension of the valve plug and the improved insert. When the rubber around the insert melts by high temperatures the valve plug will be shot out into the room by overpressure when the valve plug is smaller than the opening of the insert such that the valve plug will act as a dangerous projectile. If the valve plug is larger it will close said opening such that the overpressure not will be released. In this case the result can be that the container explodes.
There is thus a need for a double valve of the type mentioned in the opening paragraph, which has all the advantages of the conventional double valves and is just as easy to clean optimum, and furthermore is constructed to secure the container from being blown up due to a much too high overpressure without any risk for shooting at least metal parts of the valve out into the room like projectiles.
The novel and unique features according to the invention, whereby this is achieved, is the fact, that the distance between diametrically opposite places of the opening of the reinforcement ring at at least one location is smaller than the largest diameter of the valve plug while the diametrically distance at at least one other location of the opening of the reinforcement ring is larger than the first named distance, and that the elastomere part of the valve ring has at least one area, which is so much weaker than the surrounding areas, that the weaker area is deformed so much in the closed condition of the valve under influence of the load of the valve plug and the gas pressure that the mouth of the liquid passage not any more is closed, when the pressure in the container exceeds a pressure, chosen beforehand, larger than the normal working pressure in the container.
On the outside the valve looks like a conventional double valve and it can be cleaned just as easily to an optimum extend. In daily use the valve is also working in precisely the same way, but if the pressure in the container now exceeds the normal, the hidden qualities of the valve will at a certain time come into operation. This moment occurs when the pressure in the valve has rised to said predetermined higher pressure than the working pressure. The valve plug is in this case not able to close the opening of the reinforcement ring and the overpressure will therefore be released. Such, the pressure in the container now cannot, in all essentials, rise any more. In this condition the valve has automatically transformed itself into an efficiently working security valve.
This advantage is at the same time obtained without any risk for that dangerous metal parts of the double valve will be shot out into the room like projectiles. By overpressure will the valve plug be stopped by the reinforcement ring which again will be stopped by the seat of the gas passage.
In praxis the construction of the valve ring is therefore adapted in such a way that it will leak at a pressure level which on one hand is higher than the normally existing working pressures, and on the other hand is at a safe distance from the explosion limit. A container which is mounted with such a double valve will then be secured from explosion if it, for instance, should be exposed to intense heat, and without any influence on the function of the container when under normal operating conditions.
The weaker areas, which will cause the valve ring to leak at an overpressure too high, can then be provided by forming on the reinforcement ring an inwards turning collar and let the outline of the opening, which is limited by the collar, deviate from a full circle. The areas in the valve ring, where the radial distance of the collar from the valve axis is larger, will then become weaker in relation to the areas where the radial distance of the collar from the valve axis is smaller.
When there along the outline in the opening of the collar are diametrically opposite areas with smaller distance than the outer diameter of the valve plug, the plug cannot pass the opening. This construction prevents the valve plug from being shoot out into the room as a danger to the surroundings, if the elastomere material of the valve ring should give in for an overpressure. The plug is stopped by the reinforcement ring which is made of a stiff and strong material, as e.g. metal or plastic.
By an particularly advantageous embodiment the outline of the collar opening has mainly form of a circle interrupted by a number of incisions being formed in the collar with equidistant distances along the periphery. The weaker areas are formed at the incision and can optimum be adjusted to the purpose in dependence of the widnes and depth of the incisions. Since there are many incisions there will at the same time be formed a great blow-off area for the gas when the elastomere material gives in for an overpressure, whereby a high rate of security is created to the effect that the pressure will not rise further.
When the diameter of the circle outline, which is limited by the collar material between the incisions, is smaller than the inner diameter of the plug, the plug will then at overpressure, where the elastomere material of the valve ring gives in, be stopped at areas which are regularly distributed along the opening of the collar of the reinforcement ring. Thereby the collar will provide an efficient security against the plug being shooted out into the room. The plug is controlled retained in position in the valve by the many areas with smaller diameters than the outwards diameter of the plug, and can consequently not get out edgeways at the areas with larger diameters.
The weaker areas in the elastomere material of the valve ring can conveniently be weakened by dimensioning the incisions with an adequate big widnes and depth. If the joined area of the incisions, however, is too big, it can have a negative effect on the stability of the valve ring under normal working conditions and reduce the ability of the collar to stop and retain the plug from being shooted out by overpressure.
To avoid these draw backs, at least the edges turning towards the plug in the incisions of the collar can have such a sharpness that the edges cut into the elastomere material by over-pressure, but not by normal working pressure. By overpressure the elastomere material at the incisions will then be cut into pieces which, rather easily, will be pressed trough the incisions, and the size of the widnes and depth of these can consequently be reduced adequately.
The function of the double valve as security valve depends on how the weaker areas of the valve ring are being arranged. By forming a reinforcement ring, the function can be adapted to the purpose by an adequate forming of the outline in the opening of the collar.
The character of the stress acting on the valve ring by over-pressure, is furthermore of significant importance to the security function of the valve ring. This stress is due to the gas pressure, which partly influences directly on the valve ring, and partly indirectly via the valve plug. When the seat of the valve ring forms a surface of revolution which converges towards the mouth of the valve ring, the force, whereby the plug acts on the valve ring, is increased. The plug is squeezing itself into the opening of the valve ring and thereby presses the elastomere material in this latter up and outwards with great force, so that the material probably will be forced out through the incisions of the collar and opens for outflow of gas, thereby relieving the overpressure.
The elastomere material can have a very high elasticity so that the material is not broken at the weaker areas but just gives in to the stress and returns to its original shape when the overpressure is relieved.
In order to obtain optimum effect of the security device of the double valve and also be able to see whether the valve have been in function or not, whereby the container and the valve might have been exposed to damage, it will, however, be an advantage if the material is completely or partly broken at the weaker areas of the valve ring. In this case the elastomere material in itself should be rather stiff and have a small elongation.
The valve plug can in this connection mainly be formed as a spherical segment which is connected with a underlying abutting ring for the pressure spring with narrow legs in a construction which entails that most of the edge of the spherical segment is free.
By making said edge sharp, the spherical segment then will act as a sort of punch being able, by overpressure, to stamp out some of the elastomere material of the valve ring if this material is rather stiff and has a small elongation.
When first the material is completely or partly stamped out it is easily shot out through the incisions of the inside turning collar of the reinforcement ring as the plug during the stamping process is wandering into the valve ring for being stopped, at last, when abutting the reinforcement ring.
The invention will be explained more fully by the following description of an embodiment, which just serves as an example, with reference to the drawing, in which

Fig. l shows an axial section through a double valve according to the invention,
Fig. 2 is a side view in a larger scale of a valve plug for the double valve shown in fig. I,
Fig. 3 is the same, taken after the line III-III,
Fig. 4 is a view in a larger scale of a reinforcement ring for a valve ring for the double valve shown in fig. l,
Fig. 5 is the same, taken after the line V-V in fig. l, and
Fig. 6a-c show three successive steps in which the double valve by overpressure is turned into a security valve.

Fig. l shows a double valve which is generally designated by the reference numeral 1. This double valve is more or less a well-known type and therefore only roughly described here. The double valve is by a thread assembly 2 screwed into a neck ring 3 on a container 4 which can only be seen in fragment.
The container might typically be a transportable container for a beverage, as e.g. beer or cola, to be kept under pressure by a gas, e.g. CO₂. The pressure will under normal working conditions only be of a few bars.
In the valve there is a central liquid passage 5 and around this a ring-formed gas passage 6. Both passages can be closed by an axially displaceable elastomere valve ring 7, which closes the gas passage by means of the gas pressure and a first pressure spring 8 being pressed tight up against a seat 9 in the valve at the mouth of the gas passage. The valve ring itself forms with its opening l0 the mouth of the liquid passage 5 which again can be closed off by an axially displaceable valve plug 11, which by the gas pressure and a second pressure spring 12 is pressed tight up against a seat 13 in the mouth of the valve ring.
When the container is to be used the valve is mounted by a special coupling head (not shown) which can open both the gas passage and the liquid passage. The inside of the container is then connected to a pressure gas source keeping the pressure in the container on the working pressure requested. The gas is among other things working as a driving gas which by opening of a drain cock (not shown) connected to the liquid passage, is driving the liquid out to the consumption place.
When closing the coupling head the pressure is normally kept in the container, even if it is emptied for liquid. Also the full containers, coming from the producer, will have a content of pressure gas, and thus there will always be in circulation a very large amount of containers with gas holding a pressure of a few bars higher than the atmospheric pressure. The containers are, however, dimensioned on the large side to be able to resist the load from this pressure.
If a container, however, is exposed to intensive heat in e.g. a burning building, the gas pressure might then rise so heavily that the container can no longer resists. The container will then blow up with an explosive force which may be of great danger to the usually many people who are near the explosion.
This risk has been completely eliminated by means of the particular embodiment of the valve ring 7 and the valve plug 11.
Fig. 2 and 3 show the valve plug 11 with the left and the right side of the figures turning 90 degrees in relation to each other. The plug is builded up by a spherical segment 14 which with two narrow, but adequately strong legs 15, are connected to an abutting ring 16, which serves as support to the second pressure spring 12 (fig.1). The ring is in the shown embodiment closed, but can also be partially open. Between the spherical segment 14 and the abutting ring 16 there are on both sides of the legs 15 passage openings 17 for passage of the liquid. At these openings the spherical segment 14 has a sharp edge 18 which extends across the main part of the periphery of the spherical segment as the widnes of the legs only makes a very small part of the length of the latter.
Fig. 4 and 5 show a reinforcement ring 19 for inserting into the elastomere valve ring 7 for stiffening and stabilisation of this latter. The reinforcement ring has a mandrel 20 which follows the shape of the valve ring. At the top the mandrel emerges into an inside turning collar 2l which limits a circular opening 22 with eight uniformly distributed incisions 23 of a mainly rectangular shape. The reinforcement ring is, by the way, in the shape of a sheet with a comparatively thin wall thickness and it is made from a strong and stiff material as e.g. steel.
The diameter of the opening 22 is a little smaller than the outer diameter of the segment 14, and the distance from the centre of the circle to the bottom of an incision is larger than half the outer diameter of the spherical segment. Furthermore, each incision has a widnes of between 1,0% and 4,0%, preferably between 1,5% and 3,5% and especially between 2,0% and 3,0% of the circle length of the opening.
Fig. 6a-c now show how the security device is operating when the pressure in the container exceeds a certain limit, normally called the overpressure permitted.
In fig. 6a the valve plug 11 with its spherical segment 14 is resting on the valve ring 7's seat 13. The position can be the normal closed position, but can also be the start position at a pressure exceeding the acceptable where the security device of the valve is coming into function.
In fig. 6b this has taken place. The spherical segment has with great power squeezed itself into the opening 10 of the valve ring compressing the surrounding elastomere material in the valve ring into an upwards direction and simultaneously also outwards due to the pointed shape of the spherical segment outer diameter as well as of the seat of the valve ring .
In the example shown it is presumed that the elastomere material is rather stiff and has a relatively small elongation. As it can be seen the spherical segment will then be acting as a punch tool stamping with its sharp edge 18 the material 24 out of the remaining part of the valve ring. The material, which is totally or partly released, will at the same time be shot up through the inwards turning reinforcement collar 21's incisions 23 which advantageously can have sharp edges 25 cutting like knives the released material into a type of strips which are easily being able to pass the incisions.
Between the still fixed material of the valve ring and the released material there will in this way be formed grooves 26 allowing the gas to flow out to the open through the incisions 23, the material strips in these being blown out by the out-flowing gas. Thereby the pressure in the container is being relieved.
Between the incisions there may also emerge leaks and especially if the circular part of the collar opening has sharp downwards turning edges cutting the already released material below free from the collar.
Fig 6c shows the final position of the security device where the valve plug 11 has been stopped by the collar 21 of the reinforcement ring 19 since the circular opening 22 of this latter has a smaller diameter than the outer diameter of the spherical segment 14. The valve plug can consequently not be shot out of the valve as a projectile which might hit persons nearby.
As it can be seen, the double valve according to the invention will under normal conditions work as a conventional double valve. From outside it also appears as such and it can just as easily be cleaned up to the high hygienic standard which is required for containers for beverages.
Its safety qualities are hidden and are only to be seen when the valve at pressures exceeding the acceptable is transformed into an efficiently working security valve blowing at an acceptable overpressure which is far below the limit where the container can explode.

Claims

A double valve (1) for a container (4) of the type used for distribution of a liquid, e.g. beer, stored in the container under pressure of a gas, e.g. CO₂, whereby the valve defines an axis and comprises a central liquid passage (5); a ring formed gas passage (6) defining a seat (9) for an elastomere valve ring (7) is arranged around the liquid passage; a reinforcement ring (19) made of a strong and stiff material as e.g. steel and having a larger outer diameter than the inner diameter of said seat (9) is inserted into the elastomere part of said valve ring; the valve ring (7) is axially movable placed in the gas passage (6) serving the purpose of closing said gas passage (6) by, under influence of the gas pressure and the spring force from a pressure spring (8), being pressed into tight engagement with the seat (9) of the gas passage (6); an opening (22) formed in the valve ring (7) is forming the mouth of the liquid passage (5); and a valve plug (11) is axially displaceable placed in the liquid passage (5) serving the purpose of closing the mouth by under influence of the load of the valve plug (11) and the spring force from a second pressure spring (12) being pressed into tight engagement with a seat (13) formed in the opening (22) of the valve ring (7), characterized in that the distance between diametrically opposite places of the opening (22) of the reinforcement ring (19) at at least one location is smaller than the largest diameter of the valve plug (11) while the diametrical distance at at least one other location of the opening (22) of the reinforcement ring (19) is larger than the first named distance, and that the elastomere part of the valve ring (7) has at least one area, which is so much weaker than the surrounding areas, that the weaker area is deformed so much in the closed condition of the valve (1) under influence of the load of the valve plug (11) and the gas pressure that the mouth of the liquid passage (5) not any more is closed, when the pressure in the container (4) exceeds a pressure, chosen beforehand, larger than the normal working pressure in the container (4).
A double valve according to claim l, characterized in that the reinforcement ring (19) has an inside turning collar (21) limiting the opening (22), the outline of which deviates from a full circle.
A double valve according to claim 1 or 2, characterized in that the inwards turning collar (21) of the reinforcement ring (19) is limiting an opening (22) with an out-line forming a circle, which at least at one location emerges into an outline formed as an incision (23) in the collar (22).
A double valve according to claim 3, characterized in the fact that the at least one incision (23) has a wideness of between 1,0% and 4,0%, preferably between 1,5% and 3,5% and especially between 2,0% and 3,0% of the circle length of the opening (22).
A double valve according to claim 2, 3 or 4, characterized in that the collar (22) of the reinforcement ring (19) has sharp edges (25) on the side turning towards the valve plug (11).
A double valve according to each of the claims 1 - 5, characterized in that the valve plug (11) is formed as a spherical segment (14) which by narrow legs (15) is connected to an underlying abutting ring (16) for the pressure spring (12).
A double valve according to each of the claims 3 - 6, characerized in that the circle of the opening (22) of the inwards turning collar (21) of the reinforcement ring (19) has a diameter being smaller than the diameter of the spherical segment (14) of the valve plug (11).
A double valve according to each of the claims 3 - 7, characterized in that the distance from the centre of the circle of the opening (22) of the inwards turning collar (21) of the reinforcement ring (19) to the bottom of the incisions (23) is larger than the diameter of spherical segment (14) of the valve plug (11).
A double valve according to each of the claims 3 - 8, characterized in the fact that at least at one location along the outline of the opening of the inwards turning collar (21) of the reinforcement ring (19) there is a place, where the distance between the diametrically opposite areas is smaller than the diameter of the spherical segment (14) of the valve plug (11).
A double valve according to claim l or 2, characterized in that the free edge (18) of the spherical segment (14) of the valve plug (11) is sharp.
A double valve according to any of the claims 1 - 10, characterized in that the seat (13) of the valve ring (7) is formed by a surface of revolution converging towards the mouth of the valve ring (7).
A double valve according to any of the claims 1 - 11, characterized in that the elastomere material of the valve ring (7) is rather stiff with a comparatively small elongation.