US2693812A - Fuel gas tank switch-over device - Google Patents

Description

Nov. 9, 1954 J. s. JONES ET AL 2,693,812

FUEL GAS TANK SWITCH-OVER DEVICE Filed Oct. 31, 1949 2 Sheets-Sheet l James 8 Jones Sam P Jon es INVENTORS Nov. 9, 1954 2,693,812

J. S. JONES ET AL FUEL GAS TANK SWITCH-0VER DEVICE Filed 001:. 31. 1949 2 Sheets-Sheet 2 James 5. Jones 5am P Jones INVENTORS FUEL GAS TANK SWITCH-OVER DEVICE James S. Jones and Sam P. Jones, Dallas, Tex. Application October 31, 1949, Serial No. 124,634 6 Claims. (Cl. 137113) This invention relates to new and useful improvements in fuel gas tank switch-over devices.

Although the invention is particularly adaptable for use with low pressure gas systems in which a plurality of pressure tanks supply a fuel gas, such as butane, to a household or other point of use, it is equally applicable in any type of installation where it is desirable to draw a fluid under pressure from one storage container and to switch to an alternate container when the pressure in the first container has dropped to a certain point.

For the sake of convenience, the invention will be described largely with respect to its application in a butane gas system. It is to be kept in mind, however, that the invention is not limited to this use. On the contrary, it

-may be employed advantageously in many fields.

As an illustration exemplary of the problems to be solved, a simple butane or low pressure gas system may again be used. Although many types of such systems are in use, those which utilize bottles of gas under pressure are becoming of increasing importance. In the latter type of system, two or more steel cylinders or bottles are manifolded into the gas supply or service line. As the bottles become depleted, they are removed and replaced with full bottles, normally by a gas service operator. It has been found to be desirable to deplete first one bottle of gas, and then to switch to an alternate or second bottle. Of course, this switching over is preferably accomplished automatically. While devices for this purpose have been previously developed, they are expensive and have certain drawbacks, among them being the escape of gas during the bottle changing procedure and the fire and health hazards consequently brought into being.

It is, therefore, one object of this invention to provide an improved device for automatically switching pressure fluid withdrawal from one vessel to another, or from one supply source to another, when the pressure of the first vessel or supply source drops to a predetermined level.

Another object of the invention is to provide an improved device of the character described, in which provision is made to prevent the escape of pressure fluid from a vessel or supply source during disconnection of the same.

Yet another object of the invention is to provide an improved switch-over device in which there is no need for vent openings so that the breathing of moisture or dirt into the device during operation is eliminated.

A further object of the invention is to provide an improved switch-over device which is simple and durable in structure, and is economical to manufacture.

A construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to United States Patent Fig. 5 is a vertical, cross-sectional view taken upon the line 5-5 of Fig. 1,

Fig. 6 is an assembly view illustrating the connection of the device to a pair of gas bottles,

Fig. 7 is a longitudinal, horizontal, sectional view taken upon the line 77 of Fig. 1,

Fig. 8 is a longitudinal, vertical, sectional view of a modification of the invention,

Fig. 9 is a longitudinal, horizontal, sectional view taken upon the line 99 of Fig. 8,

Fig. 10 is an end view of the modification partially broken away to illustrate the structure thereof, and

Fig. 11 is a vertical, cross-sectional view taken upon the line 1111 of Fig. 8.

In the drawings, the numeral 10 designates a switchover mechanism body. The body is substantially rectangular in shape and cross-section and is provided with a depending boss 11 on its underside. A screw-threaded passage 12 extends through the boss into communication with a horizontal, longitudinal passage 13 formed in the lower portion of the body 10 and communicating between the lateral faces 14 and 15 thereof. A second and somewhat larger bore 16 also extends horizontally and longitudinally of the body 10 between the lateral faces thereof, the bore 16 passing substantially through the medial portion of said body. A reduced, vertical opening 17 extends along the vertical axis of the body between the bore 16 and the upper surface of said body.

A diaphragm and gasket 18 of substantially rectangular shape, abuts the lateral surface 15 of the body so as to cover the entire lateral base 15 and the end of the the accompanying drawings, wherein examples of the invention are shown, and wherein:

Fig. 1 is a longitudinal, vertical, sectional view of a switch-over device constructed in accordance with this invention,

Fig. 2 is an end elevation of the device, partiallybroken away to illustrate the construction thereof,

Fig. 3 is a vertical, cross-sectional view taken upon the line 33 of Fig. 1,

Fig. 4 is a vertical cross-sectional view taken upon the line 44 of Fig. 1,

bore 16. An opening 19 is provided in the lower portion of the gasket and is adapted to register with the passage 13 for communication through said diaphragm. A cap plate 20 overlies the diaphragm 18, being secured to the body 10 by a plurality of screw-threaded bolts 21 and having a central, cylindrical sump 22 axially alined with the bore 16. A gas supply fitting 23 is tapped into the sump 22 through the body of the plate 20 and is provided upon its inner end with a nozzle and seat 24 in vertical alinement with the inner face of the block 20. Upon the opposite or opposed lateral face 14 of the body 10, a similar arrangement is provided, there being a block 25 carrying a sump 26 and having a gas supply fitting 27 connected hereinto. The nozzle and seat 28 of the fitting 27 is likewise in vertical alinement with the inner face of the block 25. Both the blocks 20 and 25 have reduced passages 29 in their lower portions communicating between the sumps 22 and 26, respectively, and the bore 13. A gasket and diaphragm 30 is interposed between the block 25 and the body 10, the diaphragm being formed with an opening 31 in its lower portion in register with the passage 13. With this arrangement, the passages 12 and 13 are in constant communication with the sumps 22 and 26.

A tubular sleeve 32 has a sliding fit within the bore 16, and as is shown in Figs. 1 and 7, is slightly less in length than said bore. The latter course is of a length equal to the width or thickness of the body 10 between the lateral faces 14 and 15. The sleeve 32 is formed with a circumferential groove 33 about its medial portion, the groove being provided upon the outer surface of the sleeve so as to be exposed to the bore 16. The sleeve is further counterbored at each end to provide an internal, annular shoulder 34 spaced inwardly from each end of the sleeve and a counterbore 35 at each end of said sleeve between shoulders 34 and the said ends of the sleeve. In the right-hand end of the sleeve, as viewed in drawings, an annular ring 36 is positioned within the counterbore and adapted to seat upon the shoulder 34. The ring is of a thickness substantially equal tothe depth of the counterbore and is provided with a plurality of radially inwardly extending splines 37. The outer surface of the splines 37 adjacent the diaphragm 18 are chamfered or bevelled inwardly away from the diaphragm, as shown in Fig. 1, to provide a substantially conical recess 38 in the central portion of the ring. A substantially identical ring 39 is positioned in the lefthand end of the sleeve 32, as viewed in the drawings, and is provided with inwardly chamfered, radially-extending splines 40. The ring 39 is also substantially equal in width to sleeve 32 and is of a length somewhat less than one-half the length of said sleeve. Radial notches or recesses are cut inwardly in the extreme right-hand portion of the piston 41 to form a plurality of radially-extending splines '42 upon the end of the piston adjacent the ring 36. The splines 42 are complementary to the splines 37 and mesh therewith, as illustrated in Fig. of the drawings. The outer end of the piston 42 is flat, however, whereby the effect of the substantially conical recess 38 is eliminated when the ring 36 and piston 41 are fully telescope'd.

.A similar piston 43 is disposed in the left-hand portion of the sleeve 32 and carries Splines 44 meshing with the splines 40 of the ring 39. The pistons 41 and 43 are spaced from one another within the bore of the sleeve 32, and are held in alinernent by an axial pin '45 having a loose sliding fit within cylindrical recesses 46 and 47 extending axially of each of said pistons from the adjacent surfaces or ends thereof. As shown in Fig. 1, when the pistons are moved together as closely as possible and the pin 45 is engaging the bottom of the recesses 46 and 47, the spacing between the outer faces I of the pistons is a little greater than the axial length of the sleeve 32, but is a little less than the axial length of the bore 16. The function and importance of this arrangement will be discussed more fully hereinafter.

For permitting the shifting of the sleeve 32 within the bore 16, a shaft 48 is journaled within the opening 17 and held in this position by means of a set screw 49 engaging within an annular groove 50 cut in the shank of said shaft. An eccentrically positioned cam 51 is carried by the shaft and projects into the annular groove 33 cut in the sleeve 32. Thus, rotation of the shaft 48 will result in shifting of the sleeve 32 toward first one end and then the other of the bore 16. For operating or rotating the shaft 48, a handle 52 is secured upon its projecting end, the handle being in the general form of an arrow to indicate the bottle or gas supply from which fuel gas is being withdrawn.

In the utilization of this device in a butane system, a pair of gas bottles, A and B, are connected through suitable pipes 53 and 54, respectively, to the inlet fittings 23 and 27, respectively. A standard type of pressure regulator or reducer 55 is connected into the opening 12, and the domestic gas supply line 56 leads from said regulator. For determining the pressure at which gas is being supplied to the regulator 55, any suitable or desirable type of pressure gauge 57 is mounted in a passage 58 cut in the body and leading to the bore or passage 12. As shown in Fig. 7, the gauge carries an indicating hand 59 and a scale 60, the first portion 61 of which is preferably colored or distinctively marked in some way to indicate a low pressure or reserve gas supply zone.

In the operation of this device in a domestic fuel gas supply system, the handle 52 is turned so that the arrow which it forms points toward the bottle from which gas is to-be withdrawn. With the assumption that gas is to be drawn from the left-hand bottle A, the device will assume a position illustrated in Fig. 1 of the drawings. It is to be noted that the cam 51 moves in the opposite direction from the arrow 52, that is, when the arrow 52 points to the left, as shown in Fig. l, the cam will be shifted to the right so as to move the sleeve 32 to the right with its outer extremity in vertical alinement with the right-hand lateral surface of the body 10. Since the right-hand ring 36 is thus urged against the shoulder 34 and is of a width equal to the depth of the counterbore 35, the outer or right-hand surface of said ring will also be in vertical alinement with the lateral surface 15. On the other hand, the left-hand end of the sleeve 32 will be spaced inwardly from the left-hand lateral surface 14, and the left-hand ring 39 will similarly be inwardly spaced away from the diaphragm 30. Assuming that both the bottles A and B are full and contain gas under a pressure of 150 pounds per square inch,

there will be a pressure of 150 pounds per square inch in both of the sumps 22 and 26. For an instant, gas may flow from both bottles, but as soon as the pressure builds up in both of the sumps, there will be a differential pressure loading of the device which will shut off the flow from one bottle. In the illustration at hand, the entire area of the diaphragm 30 exposed to the sump 26 will be subjected to the full bottle pressure, and this load will be applied to the left-hand piston 43, through the connecting pin 45 to the right-hand piston 41. In opposition to this force, only the central portion of the diaphragm 18 may flex, and hence the total exerted pressure upon the right-hand diaphragm 18 is somewhat less than that applied to the left-hand diaphragm 30. This is true because the sleeve 32 and the right-hand ring 36 have been shifted to the right into engagement with the peripheral portion of the diaphragm adjacent the walls of the sump 22 to provide a support for that portion of the diaphragm. Therefore, only the inner or central portion of the diaphragm may move under the applied pressure, and since this movable area is less than the total area of the left-hand diaphragm, there will be an unbalanced force exerted across the two pistons causing both to shift to the right as shown and to press the central portion of the diaphragm 18 against the nozzle 24 thereby shutting off flow from the right hand bottle B. Thus, as fuel gas is withdrawn through the pipe 56, flow from the left-hand bottle only will take place, and the right-hand bottle B will remain full and at maximum pressure.

The condition recited above continues until the gas within the bottle A has been depleted to such an extent that its exerted pressure drops to a predetermined point. For the purposes of explanation, this point may be assumed to be 15 pounds per square inch, but it is obvious that any desired minimum pressure may be selected simply by variation of the ratio between the entire crosssectional area of the piston and sleeve structure, and the area exposed for movement when the sleeve and the splined ring is held against movement. Consideration must also be given to the fact that the very center of the right-hand diaphragm will be exposed to full bottle pressure of pounds per square inch even after the pressure in the left-hand bottle has begun to drop and the pressure within the remainder of the right-hand sump 22 has likewise dropped. With the various areas and pressures known, however, the ratios between the exposed surfaces may readily be adjusted through design so as to cause the device to function at any predetermined pressure.

When the pressure in the left-hand bottle A has dropped to, say, 15 pounds per square inch, the total force exerted upon the exposed area of the diaphragm 30 will not equal the pressure exerted upon the movable area of the diaphragm 18 plus the pressure exerted within the nozzle 24, so that the total resultant of the pressures and forces exerted tend to move the piston structure to the left, as shown in Fig. 7. It is to be noted that the sleeve 32 and the rings 36 and 39 have not been shifted, but that only the pistons 41 and 43 have been moved. When this situation obtains, the left-hand diaphragm 30 is forced against the nozzle 28 and further flow from the left-hand bottle A is terminated. The right-hand bottle B will not furnish full presered and gas begins to flow from the right-hand bottle B to build up a pressure within the right-hand sump 22, a simultaneous building up of pressure within the sump 26 through the passage 13 also occurs. When this built up pressure reaches a certain point, the greater movable diaphragm area exposed to the left-hand sump 26 will cause the pistons to again shift to the right and close ofi the nozzle 24. Thus, at this stage, the device functions somewhat as a regulator, the diaphragm 18 being the valve and the nozzle 24 being the seat, while the two diaphragms and the pistons constitute a differentially loaded controlling means preventing the pressure in the device from exceeding a certain limit.

Among other objections, one of the principal faults of prior devices has been the escape of gas while gas bottles are being changed if the pressure in the bottle in use is low. When the left-hand bottle A has been substantially exhausted and the right-hand bottle B has come into use, the somewhat lower pressure at which gas is supplied to the regulator 55 will be indicated upon the pressure gauge 57, thus swinging the indicator hand 59 into the reserve indicating area 61. This informs the user of the device and system that he is operating upon his reserve gas supply and that the bottle toward which the arrow hand 52 is pointing has become depleted. At this time, he will notify the gas service concern to replace the depleted bottle. Of course, replacement of the bottle is effected by disconnection of the pipe 53, and it is desirable to prevent the escape of gas at this point. Prior to disconnection of the bottle, the service operator will switch the position of the arrow handle 52 so that it now points toward the bottle B from which supply gas is being drawn. When this is done, the sleeve 32 is shifted to the left, reducing the area of the diaphragm which may move under pressure and increasing the area of--the diaphragm 18 which may so move. Under these conditions, the differential pressure tends to move the pistons to the left and to urge the diaphragm 30 against the nozzle 28, thereby shutting off the fitting 27 and preventing the escape of gas through the pipe 53. With this shift of the arrow hand 52, the pipe 53 is closed off and may be disconnected from the bottle A without loss of gas. A new bottle is connected in the place of the exhausted bottle A, the valve of the bottle is opened and the system remains in complete operation throughout this entire procedure. Supply gas will now be drawn from the bottle B until the same has reached the pre-determined minimum pressure desirable at which time flow will automatically switch to the new bottle of gas, although at a reduced pressure to indicate to the householder that bottle B has now been depleted.

A modification of the invention is shown in Figs. 8 through 11 of the drawings, the structure of this modification being substantially the same as that previously described with the exception of the piston and sleeve arrangement within the bore 16. For this reason, the same numerals have been employed to designate substantially identical portions of the device, and only the central or piston portion thereof will be described.

In the modification, a cylindrical bushing 62 has a snug sliding fit in the right-hand portion of the bore 16, and a similar bushing 63 has a snug sliding fit in the left-hand portion of said bore. The eccentric cam 51 projects into the space between the inner ends of said bushing, and is adapted to shift the same toward either end of the bore 16. An elongate cylindrical pin 64 fits within the bores 65 and 66 of the bushings 63 and 62, respectively, and is provided at its central portion with an enlarged annular flange or rib 67 spacing the bushings apart a pre-determined distance.

The operation of this modification of the invention is substantially the same as that given hereinbefore, the moving of the arrow handle 52 so as to point to one of the supply bottles, resulting in withdrawal of gas from that supply bottle until the pressure therein has reached a pre-determined minimum point. When this occurs, the device automatically shifts the gas withdrawal to the opposite gas bottle and continues such withdrawal at a reduced pressure. It is to be noted, that in each case, the householder is given notice of the switch-over by reason of the reduced pressure indicated upon the gauge 57. He thus receives notice that one of the gas bottles should be replaced since the fuel supply therein has been exhausted.

The bushings 62 and 63, which may also be termed rings as are the elements 36 and 39, are shifted by the cam element 51 to shift the movable exposed diaphragm area alternately from one side of the device to the other. The central pins or piston structures, 41 and 43 in the first modification and 64 in the second modification, carry out the actual transmission of the pressural forces exerted so as to close off one bottle while the other is being depleted, and further functions as the actuating shaft or stem of the regulator structure which obtains after one bottle has been depleted and while gas is being withdrawn from the other bottle at a reduced pressure.

It is to be noted that the device is completely sealed and does not require the presence of any vent-holes for pressure equalization. Since there are no vent-holes, there is no breathing of moisture and dirt into the device as it functions, and the troubles due to the presence of these foreign materials is eliminated.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What we claim and desire to secure by Letters Patent is:

l. A switch-over device for withdrawing fluid selectively from more than one source of supply, including, a body, a pair of fluid inlet conductors connected to the body, a valve seat on the end of each of the inlet conductors, a pair of diaphragms carried by the body, each diaphragm having one side enclosing the inner end of one of the inlet conductors and arranged to engage the valve seat of that inlet conductor to close off the latter, a fluid outlet from the inner ends of the inlet conductors, a piston structure of fixed length extending between and engaging the opposite sides of the diaphragms so as to support said diaphragms apart a fixed distance whereby a space of substantially constant volume is enclosed between the diaphragms, and means carried by the body for partially supporting either of the diaphragms to reduce the area thereof effective to exert force on the piston structure.

2. A switch-over device for withdrawing fluid under pressure selectively from more than one source of supply, including, a body, a diaphragm structure in the body comprising a pair of diaphragms having therebetween a fixed length piston spacing the diaphragms apart a fixed distance and ring means movable into engagement with either of the diaphragms for partially supporting an area of either of the diaphragms to reduce the area thereof effective to exert force on the piston, a pair of fluid inlets to the body having valve seats on their inner ends facing the outer sides of the diaphragms for engagement thereby, a fluid outlet from the body, and conduit means in the body connecting the fluid inlets to the fluid outlets, the area of the diaphragms partially supported by the ring means being greater than the area of the valve seats, and the diaphragm structure being movable in the body between the valve seats.

3. A switch-over device for withdrawing fluid under pressure selectively from more than one source of supply, including, a body having a bore therein and fluid inlets contiguous to the ends of the bore, a pair of spaced diaphragms disposed between the inlets and the ends of the bore for engaging and closing off the inlets, a fluid outlet from the body, conduit means in the body connecting the inlets to the outlet, a piston structure of fixed length in the bore extending between and engaging the diaphragms so as to support said diaphragms apart a fixed distance whereby a space of substantially constant volume is enclosed between the diaphragms, and means carried by the body for partially supporting either of the diaphragms to reduce the area thereof effective to exert the force on the piston structure.

4. A switch-over device as set forth in claim 3, wherein the piston structure includes a pair of shouldered pistons slidable in the bore, and a rigid member between the pistons; and the means for partially supporting the diaphragms includes rings received on the shoulders of the pistons.

5. A switch-over device as set forth in claim 3, wherein the piston structure includes an elongate piston having reduced ends engaging the diaphragms; and the means for partially supporting the diaphragms includes rings received on the reduced ends of the piston.

6. A switch-over device as set forth in claim 3, wherein the piston structure includes a pair of shouldered pistons having reduced ends engaging the diaphragms and provided with radial splines, and a rigid member between the pistons; and the means for partially supporting the diaphragms includes rings received on the reduced ends of the pistons and having splines meshing with the splines of the pistons.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,138,989 Thomas Dec. 6, 1938 2,257,249 Thomas Sept. 30, 1941 2,285,686 Shanley June 9, 1942 2,354,286 Whaley July 25, 1944 2,518,894 Humbarger et al Aug. 15, 1950

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