VESSEL FOR A PRESSURIZED FLUID

Abstract: A plastic vessel for a pressurized fluid, having an upper end wall (1) and a lower end wall (2) and an intermediate part (3) with an outer wall (4) and internal partition walls (5, 9). The internal partition walls (5, 9) are placed in such a way in respect of each other and the outer wall (4) that at least two longitudinal compartments (6, 10) for pressurized fluid are formed, which compartments (6, 10) are communicating with each other and run between the end walls (1, 2). The vessel is non-circular. The outer wall (4) between each pair of partition walls (5) has a curve (11), with a radius adapted in such a manner that the tensions arising in the outer wall (4) when the vessel is filled with a pressurized fluid will mainly be transformed solely to tensile stress in the partition walls (5) which are joined to the outer wall (4). The partition walls (5) are joined to the outer wall (4) in the border lines where two such curves (11) meet.

Description: Vessel for a pressurized fluid The present invention relates to a light and strong vessel for a pressurized fluid, arranged to withstand an internal pressure of at least 5 atmospheres It has an up¬ per end wall and a lower end wall which are both part-sperical and an intermediate part with an outer wall and internal partition walls The outer wall and the internal partition walls are firmly connected with the end walls and the internal partition walls are placed in such a way in respect of each other and the outer wall that at least two longitudinal compartments for pressurized fluid are formed These compartments are communicating with each other and run between the end walls For a long time it has been considered necessary to design vessels for a pressuri¬ zed fluid as a cylinder with a circular cross section to make them strong enough to resist the pressure from the pressurized fluid in the vessel Usually these vessels are made of metal without partition walls However, a few other pressure vessels which can have a non circular cross section have been disclosed before, Thus, the old U S patent 2,341 ,044 shows a container comprising truncated intersecting spherical shell sections A plate-like partition wall is welded to the adjacent intersecting edges of these sections The vessel is made of metal and it is very big It can have a rather square cross section Accor¬ ding to this old invention it is essential that the vessel is made of spherical shell sections, which give a rather flat construction The compartments in the vessel will be spherical and the volume of the vessel will depend on the seize of the spheres and the number of such spheres The known metal vessel has many disadvantages For instance it will be very hea¬ vy In addition the welding of the partition walls will result in weaker parts in the construction Moreover metal vessels have the drawback that the pressure in the vessel will in¬ crease when the vessel is heated This depends on the fact that the fluid stored in the vessel will have a greater volume expansion than the metal vessel In a plastic vessel the situation will be the opposite since the plastic has a higher volume expansion than the fluid To avoid that the metal vessel will be destroyed at an increased temperature the thickness of the walls has to be increased which will increase the weight of the vessel even more From the U.K. patent 1 ,522,609 it is known to produce huge metal tanks for ships, which tanks are used for storage of fluid under pressure. The tanks are obtained by welding steel plates together in such a manner that several longitudinal cham¬ bers are obtained. These known tanks have the same disadvantages as the vessel according to the above U.S. patent 2,341 ,044. According to the present invention it has been possible to avoid the above dis¬ advantages and bring about a light and strong plastic vessel for a pressurized fluid, arranged to withstand an internal pressure of at least 5 atmospheres. It has an up¬ per end wall and a lower end wall which are both part-spherical and an intermedia¬ te part with an outer wall and internal partition walls. The outer wall and the in¬ ternal partition walls are firmly connected with the end walls and the internal par¬ tition walls are placed in such a way in respect of each other and the outer wall that at least two longitudinal compartments for pressurized fluid are formed. The¬ se compartments are communicating with each other and run between the end walls. The vessel is characterized in that the partition walls are made in one homo¬ genous part with each other and with the outer wall, that the vessel is non-circu¬ lar, for example with an essentially triangular, rectangular or polygonal cross-sec¬ tion, that each compartment along the outer wall of the vessel is limited outwards by the outer wall and inwards by one, two or three partition walls of which two make a pair, whereby one end of each wall of such a pair is firmly joined to the outer wall and the other two ends of such a pair are firmly joined to each other or to a third partition wall which in its turn often constitutes a wall in a central compartment which runs between the end walls, is surrounded by peripheral compartments and communicates with these. If there is only one partition wall, its both ends are joined to the outer wall and the vessel is thereby divided in two communicating compartments. The thicknesses of the walls are well adapted to each other and the outer wall between each such pair has a curve, preferably a cir¬ cular arc with a radius adapted in such a manner that the tensions arising in the outer wall when the vessel is filled with a pressurized fluid will mainly be transfor¬ med solely to tensile stress in the partition walls which are joined to the outer wall The partition walls are joined to the outer wall in the border lines where two such curves meet, and the angle between such partition walls and each of these curves is mainly the same. Often the vessel has a mainly rectangular cross section instead of a normally circu¬ lar one Sometimes the vessel contains one or two central compartments surrounded by pe¬ ripheral compartments. This depends on the size and the form of the cross section. Thus, central compartments are usually needed at larger cross sections if a vessel with a rather flat outer side is desired. Since the outer wall as mentioned above has a curve and the thicknesses of the walls are well adapted to each other the vessel according to the invention can be produced of a considerably less amount of material than if such an adaption had not been made. The amount of material will come close to substantialy the same amount of material needed for an ideal cylinder having the same inner volume but lacking corresponding division into compartments by means of partition walls. Preferably, the central compartment or compartments have an essentially triangu¬ lar, rectangular or polygonal cross section. The vessel has an ordinary opening at the top and/or at the bottom, which opening is provided with a valve or a connection. Many different thermoplasts such as polyacetal, polyamide, polyethylene tere- phthalate, polybutylene terephthalate, polyethylene, polypropylene, polybutylene, polyvinyl chloride and polycarbonate or a thermosetting resin such as epoxy resin, polyester resin, phenol-formaldehyde resin or polyimide resin can be used for the production of the vessel. The plastic can contain fiber formed fillers such as car¬ bon fibers, glass fibres, polyimide fibers or the like. Depending on the specific design, the material and the size of the vessel it can as mentioned above withstand an inner pressure of at least 5 atmospheres, preferably at least 1 5 atmospheres and often 1 5-25 atmospheres Usually the vessel has a volume of less than 2 m 3 , preferably 10-500 litres Often the vessel is rather small, 10-200 litres. The vessel can be made in many different ways Accordingly, the end walls can be manufactured by injection moulding, preferably with integrated partition walls and the intermediate part by injection moulding or extrusion with integrated partition walls, whereupon the parts are joined by means of mirror welding for instance The vessel can also be made of two parts with integrated partition walls, which parts are then joined by mirror welding for instance In this case the two parts can be made by injection moulding or the like It is also possible to make the vessel directly in one piece for instance by means of a melt core technique. Due to the special design according to the invention, handles and the like can easily be integrated in the construction by using the border lines where the outer wall and the partition walls meet as fixing points The pressure vessel according to the invention can for instance be used as a water heater, pressure tanks for vehicles, fire extinguishers, containers for bottled gas and compressors The invention is further explained in connection with the enclosed figures of which figure 1 in perspective shows one embodiment of a pressure vessel according to the invention with mainly triangular cross section Figure 2 illustrates in a per¬ spective view another embodiment of a pressure vessel with mainly square cross- section Figures 3 and 4 show a perspective view of the same pressure vessel as according to figure 2 but some parts have been cut away to show the inside of the vessel Figure 5 shows a cross section of the vessel according to figure 1 and figu¬ re 6 shows a cross section of the vessel according to figures 2-4 Figure 7 illustrates examples of other suitable cross sections of the pressure vessel according to the invention The pressure vessel comprises an upper end wall 1 , a lower end wall 2 and an in¬ termediate part 3 with an outer wall 4 The vessel according to figures 1 and 5 have three internal partition walls 5, pla¬ ced in such a manner in respect of each other and to the outer wall 4 that three compartments 6 for a pressurized fluid are formed running between the end walls 1 , 2 The compartments 6 have a communication between them obtained by one or more openings or holes in the partition walls 5 The outer wall 4 is formed as a circular arc between each pair of partition walls At the top the vessel has an ope¬ ning with a valve 12 The vessel according to figures 2, 3, 4 and 6 has got eight internal partition walls 5 and four internal walls 9 placed in such a manner in respect of each other and to the outer wall 4 that eight peripheral compartments and one central compartment for pressurized fluid are formed running between the end walls 1 , 2 The compart¬ ments 6 and 10 have a communication between them obtained by one or more ope¬ nings or holes in the partition walls 5 and 9 The outer wall 4 is formed as a circu¬ lar arc between each pair of partition walls 5 The central compartment 10 is limi¬ ted by the four partition walls 9 At the top the vessel is provided with an opening with a valve 12 One end 7 of each wall 5 of a pair of partition walls 5 is firmly joined to the outer wall 4 and the other two ends 8 of such a pair are firmly joined to each other or to a third partition wall 9. Figure 7 illustrates cross sections of other embodiments of a pressure vessel ac¬ cording to the invention with two to twelve communicating compartments The invention is not limited to the embodiments shown, since these can be modi¬ fied in different ways within the scope of the invention.

Claims: Claims A light and strong plastic vessel for a pressurized fluid, arranged to withstand an internal pressure of at least 5 atmospheres, having an upper end wall (1) and a lower end wall (2) which are both part-spherical and an intermediate part (3) with an outer wall (4) and internal partition walls (5, 9) which walls (4, 5 and 9) are firmly connected with the end walls (1, 2) and the internal partition walls (5, 9) are placed in such a way in respect of each other and the outer wall (4) that at least two longitudinal compartments (6, 10) for pressurized fluid are formed, which compartments (6, 10) are communicating with each other and run between the end walls (1, 2) charact eri ze d in that the parti¬ tion walls (5, 9) are made in one homogenous part with each other and with the outer wall (4), that the vessel is non-circular, for example with an essentially triangular, rectangular or polygonal cross-section, that each compartment (6) along the outer wall (4) of the vessel is limited outwards by the outer wall (4) and inwards by one, two or three partition walls of which two (5) make a pair, whereby one end (7) of each wall (5) of such a pair is firmly joined to the outer wall (4) and the other two ends (8) of such a pair are firmly joined to each ot¬ her or to a third partition wall (9) which in its turn often constitutes a wall in a central compartment (10) which runs between the end walls (1, 2) is surroun¬ ded by peripheral compartments (6) and communicates with these, that if there is only one partition wall (5), its both ends (7, 13) are joined to the outer wall (4) and the vessel is thereby divided in two communicating compartments (6), that the thicknesses of the walls (4, 5 and 9) are well adapted to each other and that the outer wall (4) between each such pair (5) has a curve (11), preferably a circular arc with a radius adapted in such a manner that the tensions arising in the outer wall (4) when the vessel is filled with a pressurized fluid will main¬ ly be transformed solely to tensile stress in the partition walls (5) which are jo¬ ined to the outer wall (4), that the partition walls (5) are joined to the outer wall (4) in the border lines where two such curves (11) meet, and that the ang¬ le between such partition walls (5) and each of these curves (11) is mainly the same. Vessel according to claim 1, c h a r a ct e r i ze d i n that it has a mainly square cross section. Vessel according to claim l or2, c haract e r ized in that it contains one or two central compartments (10) surrounded by peripheral compartments 4. Vessel according to any one of claims 1-3, characte rized i n that it is made of substantially the same amount of material as an ideal cylinder having the same inner volume but lacking corresponding division into compartments by means of partition walls 5 Vessel according to any one of claims 1-3, c h a r a c t e r i z e d i n that the central compartment or compartments (10) have an essentially triangular, rectangular or polygonal cross-section 6. Vessel according to any one of claims 1-5, characteriz ed i n that it has an ordinary opening (12) at the top and/or at the bottom, which opening (12) is provided with a valve or a connection 7. Vessel according to any one of claims 1-6, cha rac t e ri zed i n that it is made of thermoplast such as polyacetal, polyamide, polyethylene terephtha- late, polybutylene terephthalate, polyethylene, polypropylene, polybutylene, polyvinyl chloride and polycarbonate or a thermosetting resin such as epoxy re¬ sin, polyester resin, phenol-formaldehyde resin or polyimide resin 8 Vessel according to claim 7, ch a ract erized i n that the plastic con¬ tains fiber formed fillers such as carbon fibers, glass fibres, polyimide fibers or the like 9 Vessel according to any one of claims 1-8, cha rac t e r i zed i n that it is arranged to withstand an inner pressure of at least 15 atmospheres 10 Vessel according to any one of claims 1-9, c h ar a c t e r i z e d i n that the end walls (1,2) are made by injection moulding and the intermediate part (3) by injection moulding or extrusion, whereupon the parts are joined for in¬ stance by mirror welding 11 Vessel according to any one of claims 1-9, c ha rac t e r i zed i n that it is made in two parts with integrated partition walls (5, 9) which parts are then joined for instance by mirror welding 12 Vessel according to claim 11, c h a r a c t e r i z ed i n that it is made by injection moulding or the like 13. Vessel according to any one of claims 1-9, cha rac t e r i z ed i n that it is made in one piece for instance by means of a melt core technique Vessel according to any one of claims 1-13, characterized in that the compression strain arising in the outer wall (4) is mainly transformed to tensile stress

Inventors: ORLOWSKI WITOLD, ORLOWSKI, WITOLD
Applicants: ORLOWSKI WITOLD, PERSTORP AB, ORLOWSKI, WITOLD
Application year: 1996
Main classification: F16J12
IPC codes: F16J12, F17C1