PRESSURE VESSEL

Abstract: A thin-walled pressure vessel having a bladder (23) includes a shell having an opening and a spout (33) disposed around the opening. A cap (37) normally closes this opening, secures the bladder to the shell of the vessel, and provides communication between the outside of the vessel and the inside of the bladder. The cap comprises a main body member (39) having an opening which receives a valve member (49) which extends out through one end of the cap and through the opposite end of the cap into the bladder (23) through an opening (47) therein. The valve member (49) engages a portion of the bladder (23) around the opening and clamps this portion against the main body member (39) to secure the bladder to the cap. As the pressure in the bladder (23) increases, the valve member (49) is forced against the walls of the opening in the main body member (39), increasing the clamping force to firmly secure the bladder to the cap.

Description: The invention relates to a pressure vessel, and more particularly to a pressure vessel having an elastic bladder for evacuating fluids contained inside the vessel. The prior art includes many pressure vessels which have a bladder disposed in a chamber defined by the vessel. For example, GB-A-2134984 describes a pressure vessel for containing fluids of a kind comprising a thin thermoplastic inner liner providing an impervious barrier to the fluids and having a substantially cylindrical middle portion connected to first and second end portions and an opening through the first end portion, an outer layer substantially covering the inner liner and having an opening substantially coincident with the opening of the inner liner, an elastic inflatable bladder disposed in the inner liner for displacing fluids out of the vessel and having an opening and closure means normally closing the openings in the inner liner and outer layer, the closure means comprising a main body member having an opening therethrough and valve means positioned in the opening of the main body member for closing the opening thereof and providing communication with the bladder. A pressure vessel with some similar features is described in DE-U-7010563. In accordance with the invention, there is provided a pressure vessel of the kind described above but in which the inner liner has a sleeve portion disposed around the opening of the inner liner and projecting outward of the vessel, the outer layer has a sleeve portion substantially covering the sleeve portion of the inner liner, the sleeve portions of the inner liner and the outer layer forming a spout, the closure means comprises a cap means engaging the spout, the valve means includes a recess for receiving a portion of the bladder disposed around the opening therein, the valve means clamping the portion of the bladder against the walls of the opening through the main body member of the cap means, the opening in the main body member has a generally frustoconical shape and the valve means has a corresponding frustoconical shape so that any force on the valve means in one direction causes the valve means to provide a greater clamping force, and securing means is provided for securing the cap means in leak-proof engagement with the spout. The prior art components used to secure the bladder require that the pressure vessel have a substantially increased thickness at the location where they secure the bladder to the vessel. The structural components are massive and include a multiplicity of close tolerance components which are costly and difficult to assemble. Also they do not fasten the bladder securely and they do not provide leak-proof communication with the bladder. In contrast, the pressure vessel of the present invention includes a bladder with a securing structure which has a small number of components with sufficiently accurate and consistent tolerances to provide leak-proof communication between the outside of the vessel and the inside of the bladder, and which also provides a clamping action to effectively secure the bladder to the shell of the vessel. The outer shell can comprise a layer of glass filaments bound by a resinous material to each other. The inner surface of the spout can include a threaded portion which engages a corresponding threaded portion of the cap when this closes the opening. This connection and a washer disposed in compression between the cap and the spout provide a leak-proof seal between the cap and the shell of the vessel. The main body member of the cap can be made from a hard plastics material with high strength and rigidity, with the center of the main body member having an increased thickness. Consequently, the opening through this area is elongated, and it has a generally frustoconical shape. The valve member can be a conventional air pressure valve of a shape corresponding to the shape of the opening through the main body member in which it lies. One end of the valve extends out of the vessel where the user may connect it to a suitable gas supply. A nut threaded around this end secures the valve member in place in the opening of the main body member. The other end of the valve member extends into the bladder. When the user injects a gas in the bladder through the valve, the pressure in the bladder increases. This pressure forces the valve member to move further into the opening of the cap member, increasing the clamping pressure against the portion of the bladder which it secures. This feature provides sufficient clamping pressure to firmly secure the bladder to the shell of the vessel. It, in addition to the substantial length of the opening through the cap, also provides a leak-proof seal between the walls of the valve member and the walls of the opening through the cap. The bladder is made out of a flexible synthetic rubber or any other suitable material. Fully inflated, it has the shape of the shell, and it completely fills the chamber of the vessel. As it expanded, the bladder displaces the liquid fluid which the vessel contains, forcing the fluid out of the vessel through a port in the shell. For a more complete understanding of this invention, reference should be made to the following description and the accompanying drawings, in which: Fig. 1 is a side elevation view of a pressure vessel embodying the present invention, with portions shown broken away; Fig. 2 is a fragmentary sectional view of the middle portion of a cap of the vessel of Fig. 1; Fig. 3 is a fragmentary sectional view of Detail A of Fig.1; Fig. 4 is a perspective view of a main body member of the cap. Turning now to the drawings, Fig. 1 shows a pressure vessel generally at 10. The vessel 10 is a cylindrical tank capable of containing various fluids, normally liquids. It comprises a hollow shell 11 having an elongate cylindrical body 13 and domed top and bottom portions, 15 and 17, respectively. The hollow shell 11 includes an inner liner 19 made of a suitable thermoplastic material such as polyethylene or any other high strength, impervious material. The inner liner 19 is the inside layer of the shell 11, and it has the same general shape as the outside surface of the vessel as described above. In addition to the inner layer 19, the shell 11 includes an outer layer 21 which covers the inner lining 19 and provides strength, rigidity and structural integrity to the vessel. This outer layer comprises glass filaments bound by a resinous material to each other and to the lining 11. Together, the inner liner 19 and outer layer 21 form a thin-walled, light-weight shell. The vessel 10 also includes a bladder 23 disposed in the shell 11. Preferably, this bladder 23 is made from thermoplastic material like the material of the inner liner; and the manufacturer blow molds the bladder along with the inner liner. Alternatively, the bladder may be made from an elastic material such as synthetic rubber or any other suitable material. Fully inflated, the bladder assumes the shape of the shell, and it completely fills the chamber of the vessel. By inflating it, the user can evacuate the shell 11 of any fluid because as the bladder expands it displaces the fluid, usually a liquid, and forces it out of the vessel. To provide access to its chamber, the shell 11 includes a port 25 through the domed bottom portion 17. (See Fig. 3). The port 25 extends through a spout 27 which is a portion of the inner liner 19 and which projects outward of the liner 19 through an opening 29 of the outer layer 21. The user may fill and evacuate the vessel 10 through this port. To provide access to the bladder 23, the shell 11 includes a port 31 through the top domed portion 15. The inner layer 19 and the outer layer 21 of the shell 11 project outward of the vessel to form a cylindrical spout 33 around the opening. This spout 33 also includes a sleeve 35 disposed circumferentially the port 31 and bonded to the inner layer 19 of the spout 33. The sleeve 35 is made from a hard plastic with high strength and rigidity. Its inner surface has threading formed into it for receiving a cap 37 which normally closes the port 31. The cap 37 includes a main body member 39 having a generally circular shape with a rim which comprises a threaded portion 40 and a flange 41. The threaded portion 40 engages the corresponding threaded portion of the sleeve 35 to secure the cap over the port 31. The flange 41 overlies the outer rim 43 of the spout 33 and compresses a flexible o-ring washer 45 disposed between the flange 41 and the rim 43. This washer 45 and the threaded connection between the spout 33 and the cap 37 provide a leak-proof seal between the cap and the shell 11. In addition, the main body member 39 has a wide center portion 46 and an opening 47 through this center portion. This opening 47 has a generally frustoconical shape; and it receives a valve member 49 having an outer shape corresponding to that of the opening. Since the center portion through which the opening 47 extends has an increased width, the opening 47 has a substantial length. In addition, the valve member 49 lies in this opening 47 in pressure contact with the walls of the opening. (See discussion in the following text). These features provide a leak-proof seal between the cap 37 and the valve member 49. This valve member is a conventional air pressure valve, and it extends through the opening 47 at both ends, closing the opening. At one end, the end which extends through the outer surface of the cap 37, it includes a threaded portion 51 which a nut 53 engages to secure the valve to the cap member so that it does not fall back into the bladder. At the opposite end, the valve member 49 extends into the bladder 23 through a round opening 54 in the bladder. A recess 55 formed around the sides of the valve member 49 receives the portion 57 of the bladder circumferentially this opening. When placed in the position shown in Fig. 2, the valve member 49 clamps the bladder portion 57 to the main body member 39, securing the bladder 23 to the cap 37. As the user of the vessel 10 inflates the bladder and the gas pressure in the bladder 23 increases, it forces the valve member 49 outward of the vessel 10, increasing the clamping force on the portion 57 of the bladder. Additionally, as the bladder expands, it displaces the fluid which the vessel contains, forcing the fluid out of the vessel through the port 25. Fully inflated, the bladder 23 assumes the shape of the shell 11, fills the shell completely, and evacuates all of the fluid from the vessel. Thus, the invention provides an improved vessel having a bladder for evacuating the vessel and a cap for securing the bladder to the walls of the vessel and allowing leak-proof communication between the outside of the vessel and the inside of the bladder. The cap is a simple structural component having a body member with an opening which receives a valve member for securing the bladder to a cap and providing access to the bladder. As the pressure of the fluid in the bladder increases, it forces the valve member against the side walls of the frustoconical opening, thus providing greater clamping pressure to hold the bladder against the cap.

Claims: A pressure vessel for containing fluids, the pressure vessel comprising a thin thermoplastic inner liner (19) providing an impervious barrier to the fluids and having a substantially cylindrical middle portion connected to first and second end portions and an opening through the first end portion, an outer layer (21) substantially covering the inner liner (19) and having an opening substantially coincident with the opening of the inner liner, an elastic inflatable bladder (23) disposed in the inner liner for displacing fluids out of the vessel and having an opening and closure means normally closing the openings in the inner liner and outer layer, the closure means (37) comprising a main body member (39) having an opening therethrough and valve means (49) positioned in the opening of the main body member for closing the opening thereof and providing communication with the bladder, characterized in that the inner liner (19) has a sleeve portion disposed around the opening of the inner liner and projecting outward of the vessel, the outer layer (21) has a sleeve portion substantially covering the sleeve portion of the inner liner, the sleeve portions of the inner liner and the outer layer forming a spout (33), the closure means comprises a cap means (37) engaging the spout, the valve means (49) includes a recess for receiving a portion of the bladder disposed around the opening therein, the valve means clamping the portion of the bladder against the walls of the opening through the main body member of the cap means, the opening (47) in the main body member (39) has a generally frustoconical shape and the valve means (49) has a corresponding frustoconical shape so that any force on the valve means in one direction causes the vale means to provide a greater clamping force, and securing means (45) is provided for securing the cap means in leak-proof engagement with the spout. A pressure vessel as claimed in claim 1 wherein the securing means comprises a washer (45) disposed in compression between the cap means and the spout. A pressure vessel as claimed in claim 1 or 2 wherein the securing means comprises a threaded portion on the inner surface of the spout engaged by a correspondingly threaded portion (40) of the cap.

Inventors: YAVORSKY, WILLIAM M.
Applicants: ECODYNE CORPORATION
Application year: 1987
Main classification: F16J12
IPC codes: F15B1