US 3018914 A
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2 Sheets-Sheet 1 5 I ||||||l||l|| A MVO Q m w H 2 V a Jan. 30, 1962 M. E. WEBSTER PRESSURE CONTAINER CONSTRUCTION Filed July 11, 1958 MILO E WEB$7ER BY V 7 3 Du.
Jan. 30, 1962 Filed July 11, 1958 M. E. WEBSTER 3,018,914
PRESSURE CONTAINER CONSTRUCTION 2- Sheets$heet 2 INV EN TOR MILO E. WEBSTER BY Bl-aLaQSS D 50 ATTORN S nited States York Filed July 11, 1958, Ser. No. 747,974 3 Claims. (Cl. 22tl--3) This invention relates to an improved pressure container construction. The invention more particularly relates to a pressure container having a novel bushing, and to the bushing per se.
While the invention is applicable to pressure containers in general regardless of their intended use, the invention is particularly intended for LP. cylinders containing for example liquefied propane and more particularly to small L.P. cylinders of the throw-away type.
In recent years a number of portable appliances which operate oil LP. gas and particularly propane have been widely marketed to the home consumer and various trades. These appliances include, for example, blow torches, lanterns, cook-stoves, grilling devices, fire pots, leak detectors and the like. The commercial success of these items has been predicated upon a convenient, readily available and inexpensive source of LP. gas.
Due to its highly inflammable nature the sale and transportation of LP. gas is strictly regulated. In the past only relatively large, permanent refillable cylinders were available for LP. gas. These cylinders were generally too bulky to be considered truly portable, and their expense and the inconvenience entailed in having the same refilled at an authorized station (which was not generally too accessible) for the most part precluded their purchase and use by the ordinary amateur handyman and general public.
Not until the development of the small portable throwaway cylinder did the use of portable propane operated tools and other appliances become wide spread among the average purchaser. The portable throw-away L.P. cylinder could be purchased in any ordinary hardware store, could be used interchangeably with various L.P. appliances and when the supply of LP. gas was exhausted, could be thrown away avoiding the inconvenience and natural purchaser resistance to items that had to be returned and/or refilled.
In connection with any throw-away item, cost is of course a prime consideration. This is particularly true with the LP. cylinders since regulations require that the same be sturdily constructed of relatively heavy gauge steel and must meet extremely high safety requirements. In spite of these difiiculties, modern drawing techniques with the use of automatic punch presses and mass production made successful marketing of these throw-away LP. cylinders possible.
The cylinders must have a bushing for attachment of a tap connection so that the appliance in connection with which it is being used may be attached to the cylinder to withdraw or tap the LP. gas. Thesebushings were conventionally turned from relatively heavy metal stock, as for example on an automatic screw machine, and constituted one of the prime obstacles in a further reduction in the cost of the cylinders. In order to facilitate production the same were made of easily machinable steel which had a high lead content which would not allow welding. It was therefore necessary to braze these bushings to the cylinder. Due to the relatively heavy mass of the bushing, as compared with that of the cylinder wall, the cylinder would heat up much more rapidly than the bushing, presenting further brazing difficulties.
In addition, in order to preclude the possibility of explosion an excess pressure relief valve had to be provided.
Patented Jan. so, teen This valve was conventionally positioned in a machined housing also brazed in the cylinder, and further increased the cost of the cylinder.
One object of this invention is a novel bushing construction which substantially reduced the cost and eases fabrication of the cylinder, and which is actually superior in many respects to the previously machined bushing.
A further object of this invention is a punched housing for an excess pressure relief valve reducing the cost as compared with the previously machined housing. These and still further objects would become apparent from the following description read in conjunction with the drawings in which:
FIG. 1 is a vertical section of an embodiment of a portable throw-away LP. gas cylinder with the novel bushing and relief valve housing in accordance with the invention;
FIG. 2. is a top elevation of the cylinder shown in FIG. 1;
FIG. 3 is a vertical section of the novel bushing in accordance with the invention shown on an enlarged scale;
FIG. 4 is a vertical section on an enlarged scale of the relief valve housing in accordance with the invention; and
FIG. 5 is a perspective View of the cylinder shown in FIG. 1 with a blow-torch connected thereto for use.
In accordance with the invention the bushing for attachment of a tap connection thereto on the pressure container such as the LP. cylinder has an annular outer wall portion inwardly reversed, bent at its free end portion and extending in the form of a central tubular stem coaxially with said outer wall portion defining an annular space between it and said outer wall portion. The tubular stem extends in an opening defined in the container and at least one of the stem and outer wall portions are attached in sealing engagement with the container wall. Preferably, both the tubular stem and outer wall portion are attached to the container as for example, by brazing. The bushing is stamped or punched of sheet metal of substantially uniform wall thickness, and preferably of wall thickness not substantially greater or less than that of the cylinder. The outer cylindrical wall has an external male screw thread which is preferably rolled thereon and the tubular stem is preferably tapered and provided with an internal female screw thread and a seat for a conventional tire core valve. The safety valve housing is preferably formed of a punched sheet metal extended tubular housing positioned in and sealed as, for example by brazing or welding to the periphery of a hole or opening in the cylinder wall.
The invention will be described in further detail with reference to the embodiments shown in theaccompanying drawings.
The cylinder as shown in FIG. 1 has a lower half portion 1 and upper half portion 2 which are brazed or welded together at the joint 3. Each of these halves are punched from sheet steel on a punch press using conventional deep drawing techniques, a progressive die and a multiple number of drawing steps. The lower portion is provided with a base cap 4, which is punched out of similar sheet steel and welded or brazed to the bottom of the cylinder in order to provide a stable base on which the cylinder may stand upright. The top of the upper portion 2 is stamped to provide the opening 5 surrounded by the shaped flange portion 6 and with the opening 7. The bushing for the tap connection 8 is connected at the portion 6 by for example, brazing at 9 or 10, and preferably both at 9 and 10, or welding for example at 9. The bushing 8 as may best be seen from FIG. 3 has an outer annular and preferably cylindrical wall portion 11 provided with external male screw threads, a reversed bent free end portion 12 which is extended in the form of a central tubular stem 13 which is co-axial with the outer wall portion 11 and defines an annular space 14 between it and the outer wall 11. The tubular stem 13 extends in through the hole and is tapered in a steplike manner. An O-ring rubber gasket 15 held in place by the aluminum retaining ring 16 may be positioned in the conventional manner in the tubular stem. The inner bore of the stem 15 is female screw threaded with the threads 17 and a conventional tire valve 18 is screwed in place, so that its external seat is in sealing contact against the seat surface 19 defined in the stem.
The bushing 8 may be produced from ordinary sheet steel as for example, of comparable thickness to that of the cylinder Walls. The sheet steel is first punched in the form of a disc and then using a punch press machine and a progressive die with for example a multiple number of stages, as for example 12 stages, is punched out into the shape shown. Thereafter same may be placed in a chucking machine and the external male threads 11 rolled on and the internal female threads 17 tapped into position. After decreasing bushing is then ready for attachment to the cylinder.
In contrast to previous machine-turned bushings, the same way be welded into place since it is constructed of conventional sheet steel. Furthermore, if the same is brazed in place, the brazing is greatly faciliated since the mass of the bushing wall is comparable to that of the cylinder wall and both portions being brazed will reach brazing temperatures at approximately the same time. Furthermore, the brazing may be effected at two points, i.e. at the annular areas 9 and 10, double safeguarding against any change for failure. Furthermore, the bushing is much lighter than conventionally turned bushings, so that the cylinder is much better balanced and much less likely to tip over and is more stable when standing upright.
An elongated tubular housing 20 is positioned in the opening, as for example by brazing or Welding. This housing 20 as may best be seen from FIG. 4 is punched from a disc of sheet metal in a similar manner as a bushing 8, but requires a lesser number of drawing stages, as for example, 7 to 9. The housing has the threaded portion 21 into which the relief valve 22 is screwed. The relief valve has a valve member 23 which seats against the edges of the opening 24. Excess pressure in the cylinder forces the valve member 23 against the spring pressure, off the seat allowing relief of this pressure through the opening 24. The upper end of the housing has a slightly larger cylindrical diameter at 25 with an outwardly fiared edge 26 which is sealed to the edges of the opening 7. This housing is much cheaper to fabricate than the conventional machine-turned housing previously used and may be welded in place, whereas the previous housing could not be, as the same was constructed of high lead content steel to facilitate machining.
In all other respects the cylinder construction and operation is conventional, as for example, identical to the well known and readily available Bernz-O-Matic cylinders. When it is desired to connect an appliance to the cylinder, a tap connection is screwed over the bushing 8 with its screw engagement with the threads at 11. The tap connection has an elongated hollow stem which extends down into the tubular stem 13, in sealing engagement with the O-ring 15 pressing on the stem of the tire valve 18 thus forcing the tire valve open and allowing the contents of the container to be tapped through the tubular stem 13, the hollow stern of the tap connection and out of the tap connection. The tap connection and its use is conventional and is well known and an embodiment is for example, described in the United States Patent No. 2,793,504.
FIG. 5 shows the cylinder of FIG. 1 with a blow torch connected thereto and positioned in a conventional manner.
While'the invention has been described in detail and is preferred in connection with LP. gas cylinders, the same is also applicable in connection with other pressure containers, and various changes and modifications of the invention which fall Within the spirit of the invention and scope of the appended claims will become apparent to the skilled artisan.
1. In a container for pressurized fluid, such as LP. gas, having an outer wall and an opening defined therein with an associated bushing for attachment of a tap connection thereto, the improvement in the bushing construction which is formed of stamped sheet metal, comprising a substantially cylindrical annular outer wall provided with an external male screw thread, said outer wall being inwardly reversely bent at one end thereof and extending in the form of a central tubular stem coaxial with said outer wall and defining an annular space between it and said outer wall, said tubular stem extending in said opening defined in said container and at least one of said stem and outer wall being connected in sealing engagement with the container wall.
2. Improvement according to claim 1 in which said tubular stem tapers inwardly in a step-wise manner and defines an internal female screw thread and a seating surface for a tire core valve.
3. Improvement according to claim 2 in which said bushing is constructed of sheet steel of substantially uni-. form wall thickness,
References Cited in the file of this patent UNITED STATES PATENTS 2,172,311 Thomas Sept. 5, 1939 2,518,637 Priess Aug. 15, 1950 2,673,663 Calabro Mar. 30, 1954 2,807,938 Skousgaard Oct. 1, 1957 2,835,534 Galeazzi May 20, 1958 2,904,232 Gersten Sept. 15, 19 59