US2996892A

US2996892A - Volatile fuel flow control valve

Info

Publication number: US2996892A
Application number: US766571A
Authority: US
Inventors: Thomas R Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-10-10
Filing date: 1958-10-10
Publication date: 1961-08-22
Anticipated expiration: 1978-08-22

Description

Aug. 22, 1961 T R, CLARK 2,996,892

VOLATILE FUEL FLOW CONTROL VALVE Filed 001;. 10, 1958 United States Patent() 2,996,892 j VOLATILE FUEL FLOW CONTROL VALVE Thomas R. Clark, 1310 W. 15th St., Long Beach Z, Calif. Filed Oct. 10, 1958, Ser. No. 766,571 2 Claims. (Cl. 6251) The present invention relates generally to the lield of control valves, and more particularly to a novel control valve and method of using same whereby any desired ow of a highly volatile fuel such `as butane, propane, isobutane, or a mixture thereof, may be made available to a carburetor at a substantially constant pressure to be mixed with air, although the stored source of the fuel varies widely as to pressure due to ythe temperature conditions to which it is subjected.

While the use of gasoline as a fuel to power conventional -internal combustion engines is generally well known, a less familiar form of -fuel for this purpose is that of liquefied petroleum gases, which is rapidly gaining recognition and acceptance. Such fuels are generally butane, propane, isobutane, or a mixture thereof. The virtue of these fuels, generally referred to in the trade as L.P.G. fuels, is that they are considerably less expensive than gasoline on a gallon-for-gallon, as Well as on a mileage basis. In contrast to gasoline which remains in the liquid state for a relatively long period of time even out in the open and at elevated temperatures, liquefied petroleum gas fuels are exceedingly volatile. Propane, for instance, boils at 42 F.

It will be readily appreciated that when L.P.G. fuels are used to power internal combustion engines, strong storage tanks must be used therefor due to the high vapor pressures developed thereby, which can rise to as much ias 250 lbs. per square inch when a storage tank containing same is exposed to the summer sun. This is in distinct contrast to the relatively low vapor pressures developed by gasoline when stored in a confined space and subjected to the same elevated temperatures. However, the differences between gasoline and liquefied petroleum -gases when used as fuel for internal combustion engines is not merely that of storage, vbut extends to different methods of delivery to the carburetor for mixing with air to provide an explosive mixture which is subsequently employed in powering the engine.

Provision of a constant ow Iof atomized gasoline from a jet or jets to a carburetor for mixture and vaporization with an incoming stream of air to provide an explosive mixture of a desired fuel/ air ratio is relatively simple. Gasoline in the storage tank is a-t -atmospheric pressure. The pressure on the gasoline from the fuel pump is held constant by a calibrated spring, and the gasoline inlet valve in the oat bowl of the carburetor is controlled by a sealed float of unchanging buoyancy. It will be apparent that there is nothing in the gasoline fuel supply system to cause variation in the rate of gasoline discharge from the fuel supply jets, and metering of the fuel is constant. When metering of gasoline from the supply jets is correct, and all other operating factors of the engine are likewise correct, engine performance will be at a peak. Peak performance of an internal combustion engine powered by L.P.G. fuels may also be attained if there is uniformity of pressure at the fuel supply jets at the carburetor where the fuel is mixed with Attainment of uniform pressure with resultant uniformity of flow of liquefied petroleum gases at the discharge jets of a carburetor -is not the simple operation possible by use of gasoline as fuel. The added diiculties encountered in attaining uniform pressure with uniform ilow of L.P.G. -fuel at the discharge jets is readily apparent when it is recalled that these gases are not stored at atmospheric pressure, but `are under a pressure of as little as 20 lbs. per square inch on a cold winter morning and as high as 250 lbs. per square inch on a hot summer day.

In utilizing liquefied petroleum gases as fuel, it has been common practice to withdraw the fuel from the storage tank, cause it to flow through at least one, and sometimes l two pressure-reducing valves, then through a heat exchanger, and ultimately delivered to thedischarge jets of the carburetor. However, due to the wide pressure liuctuations of L.P.G. fuel in the storage tank caused by external temperature conditions, no pressure-reducing valve or series of valves has been -available heretofore that could eiciently respond to such fluctuations, `together with the varying fuel demands of an engine when change in load occurs, to constantly provide uniform pressure of fuel at the discharge jets.

Due to the lack of a device or method that assured constant pressure of liquefied petroleum gas at a discharge jet or jets in a carburetor, internal combustion engines in the past have not attained the economy theoretically possible by the use of such fuels, countless millions of gallons of L.P.G. fuel are wasted each year because of incorrect fuel/air ratio, and the poor results attained on some liquefied petroleum gas installations have Ibeen so Vbad as to create considerable discontent amongst the owners or operators thereof.

A major object of the present invention is to provide a method and an automatically operated control valve that carries out this method to supply liquefied petroleum gas fuel to the discharge jet or jets of a carburetor under substantially constant pressure, irrespective of the varying load demands of the engine of which the carburetor forms a part, or fuel pressure variations in the storage tanks caused by external temperature changes over which 4the operator of the vehicle has no control.

Another object of the invention is to supply -a method and device for carrying out that method which not only assures operation of internal combustion engines powered by liquefied petroleum gas with the same peak eciency attainable with gasoline powered units, but in so doing, maintaining the L.P.G. fuel in the storage tank at a sufficiently refrigerated temperature to prevent fuel blow- 0E through the pressure relief valve and avoid waste as well as fire hazard.

Yet another object of the invention is to provide a lightweight, compact, inexpensive control valve that is adapted to be calibrated and sealed at the time of manufacture for a particular fuel and for certain operating conditions, and upon installation serve to selectively and alternately withdraw liquefied petroleum gas fuel from the storage tank in which it is situated to maintain the stored fuel at a predetermined temperature and pressure, as well as supply fuel under constant pressure to the discharge jet or jets of a carburetor.

,Still another object of the invention is to encourage increased use of liquefied petroleum gases as fuel for internal combustion engines by substantially eliminating the operational diliculties and disadvantages previously encountered in the utilization thereof.

These and other objects and advantages of the present invention will become apparent from the following description thereof, and from the accompanying drawing illustrating same, in which:

FIGURE 1 is a side elevational view of the present invention, showing the piping connection same to a liquefied petroleum gas storage tank;

FIGURE 2 is a Vertical cross-sectional View of the invention shown in a position wherein liqueed petroleum gas vapor only is delivered to the outlet line; and,

FIGURE 3 is a second vertical cross-sectional view of the invention shown in a position to deliver liqueed petroleum gas liquid only to the outlet line.

With continuing reference to the drawings for the general arrangement of the invention and the steps by which it carries out applicants method previously mentioned, it will be seen that a storage tank D is provided which is constructed to hold asubstantial quantity of a liquefied petroleum gas such as 1butane, isobutane or propane. Tank D has a rst valved vapor discharge outlet E and a second valved liquid discharge outlet I. Tank D also has lling facilities, and may include additional accessories such as a liquid level gauge, pressure gauge, pressure relief valve, and the like, which form no part of the present invention.

The control valve referred to herein generally and as an integral unit by the letter K, is best seen in detail in FIGURES 2 and 3. Valve K includes aY hollow main body or housing Q that defines a circular first valve seat R within the interior thereof, a liquid fuel inlet A above the seat, a vapor fuel inlet B on the lowermost portion thereof, and a fuel outlet C situated below seat R. A resilient diaphragm L extends across the top of body Q and is gripped in a fixed position thereon between the upper surface of the body vand the lower" surface of a backing plate T and a cup-shaped housing U in which a helical actuating spring H is disposed.

Spring H is at all times in compression and the lowerend thereof abuts against a spring guide V which transmits the compressive force of the spring to a valve plunger W. The lower surface of plunger W is in abutting contact with the upper central portion of diaphragm IJ. An elongate valve member M having an intermediately disposed portion that is adapted to effect a fluid seal with seat R is longitudinally movable in housing Q. Valve member M cooperates with housing Q to dei-lne an upwardly extending annulus shaped space X of extremely small width that leads to a liquid chamber P formed in the upper extremity of the valve body. A by-pass or bleed passage'O, the purpose of which will be explained hereinafter, extends from chamber P to a communicating position with fuel outlet C. t

` A vapor inlet orifice Y is removably mounted in vapor inlet opening B. The upper surface of orifice Y serves as a second seat Z which the lower surface of valve member M can contact to obstruct the ow of liquid fuelV through the orifice. A second helical spring N encircles the lower portion of valve member M, and while only a small fraction of the strength of spring H, spring N still is under suicient compression at all times to maintain the upper surface of the`valve member M in contact with the center portion of diaphragm' L.`

A tube connects liquid fuel inlet'A with valved liquid fuel discharged `on tank D, asbest seenin FIG- UREY 1. VA tube 12 extends from'orice Y tofofutlet E, also shown in FIGURE l. The fuel 'outlet C's connected by a tube 14to a pressurel reducing valve"(not shown) that in turn is in communication with`a Iheat exchanger (not shown) from which vaporized liquefied petroleum gas fuel is delivered to the carburetor (not shown) under substantially constant pressureY for mixing with air to obtain an air/ fuel mixture of the desired ratio.

The operation of valve K in maintaining the liquefied petroleum gas fuel in tank D under a subsequent oonstant pressure, irrespective of the external temperature to which the tank is subjected, as well as variations in the demand for fuel as the engine load changes,"is` as follows. 'After tank D has been lled with Vliquefied petroleum fuel for the irst'time, the valvedoutlets E and J are placed in'thefully openf'position and will thereafter so remain until tank D is removed fromthe equipment on which it is mounted to permit. aA Ynaloi; repair of the equipment.

Lqueed petroleum gasin tank D under highvvapor pressure immediately flows throughtube.12',torenterrvalve body Q through inletA thereof. This L.,P.G,.4 fuel will plunger W and spring guide V upwardly against the compression oered by spring H from the position shown in FIGURE 3 to that shown in FIGURE 2. Although resilient, diaphragm L is stretched so little when occupying the position shown in FIGURE 2 that it has no appreciable effect in counterbalancing the tendency of compressed spring H to expand. The sole function of diaphragm L is'to provide apliable, resilient barrier between the interior of valve body Q and the interior of housing U.

` TheV pressure on the liquefied petroleum gas as it enters valve body Q is transmitted to spring H to further compress same solely through that portion of diaphragm L directly under the lower ilatl face 18 of valve plunger W. Upon entering valve body Q the fuel flows upwardly therein throfugh annulus shaped space X to ll chamber P, and from the chamber through by-pass O. By-pass O is of such cross section that liquid can flow therethrough at a faster rate than it can enter chamber P through annulus shaped space X. The communication aiorded by space X, chamber P and by-pass O at all times assures that the pressure in fuel outlet O will be the same within practical limits as that existing in the interior of tank D. Flow of liquid fuel through space X, chamber P and by-pass O will only take place when the pressure in fuel outlet C is lower than that prevailing in tank D. "Thus, while the pressure on the liquid fuel delivered. to valve K, as well as that prevailing in tank D is of sufficient magnitude to compress spring H and permitspring N to lift valve member M to the position shown in FIGURE 2, the pressure in tank D immediately thereafter starts to drop. The reason for this initiation of pressure drop in tank D is that vapor from the liqueed petroleum gas in the tank can ow through orice Y, through valve K' to discharge through outlet C. However, orice Y' is so selected and of such size that the quantity of fuel vapor flowing therethrough will, with what liquid fuel that discharges from by-pass O, just supply the engine (not shown) when it is idling or subjected to a light load.

As fuel vapor in tank D discharges through orifice Y' to outlet C,` additional vapor must be formed in tank D to. replace that withdrawn. Such vapor can only be. provided by the transformanoe of liquid fuel in tank D to the vapor state. Vaporization of the. liquid fuel requires heat, which must be supplied either from the liquid fuel orv by conductance of heat from the ambient atmosphere through the wall structure defining tank D. Actually, heat comesfrom both sources.

Thus, it will be seen that even after the engine operates for a prolonged period of time at idling speed, suilicient Vaporization can occur in tank D to cause the vapor pressure therein to drop to the extent that uid inl chamber P is insuicient to force valve member W to maintain spring H in maximum compression (FIG- URE 5,) whereby the spring expands to move valve member M into the position shown inv FIGURE 2. Valve member M is then out of sealing engagement with seat R, and liquid fuel can ow from tank D through inlet A, valve body Q, to fuel outlet C without in any way appreciably affecting the temperature of the fuel in 'theA tank. The4 increased space'intank D created by the normal flow of liquid as above described is so small relativeto the already existing., space in the tank as to have no measurable effect on the rate of fuel Vaporization, with consequent cooling thereof. During the period liquid fuel flowsV from tank, D, heat is conducted from.. thel exterior tothe interior of the tank,y and 'when the temperature of the fuel remainingl in tank D rises sufficiently, theA vapor pressure thereof causes the fuel in chamber P to movevalve member M from the position shown in FIGURE 3 to that shown in FIGURE 2.

From theA above description it will be seen that the operation of the valve K is automatic as valve member normally be under sulcient pressure toy mol/Q valve alternatelymoves rfrom and to the positions shown in 2 and 3 to refrigerate and then permit heating of the liquid fuel in tank D to maintain the liquid under substantially constant pressure.

When valve member M is in the position shown in FIGURE 3 where vaporized fuel is supplied to outlet C from orifice Y, and the load 'on the engine (not shown) is suddenly increased, the response of valve K to an increased demand of 4fuel is extremely fast. This sudden increased demand for additional fuel momentarily lowers the pressure in fuel outlet C and establishes a 'differential in pressure that quickly drains the liquid` fuel from chamber P through by-pass O. -Inasmuch as liquid fuel can ow out of chamber P through by-pass O at a faster rate than it can enter the chamber Ithrough annulus shaped space X, the pressure on valve plunger W is reduced, and valve member M moves from the position shown in FIGURE 2 to that shown in FIG- URE 3. Liquid fuel then fiows from inlet A through valve body Q to fuel outlet C to meet this sudden increased demand.

In detail, it has been found convenient to cast, or otherwise form, the body Q in a generally tubularshape in which a bore 20 is formed that extends a portion of the length thereof and terminates at the seat =R. Vapor inlet B is preferably a tapped bore 22 that is coaxially aligned with bore 20, and of sufficient transverse cross section to permit threaded removable engagement thereof by the orifice-defining vapor inlet member Y. Removability of member Y is highly desirable in order to permit interchange and substitution of members having various orifice sizes formed therein, each of which is adapted for use with a particular liquiiied petroleum gas, as well as a particular range of operating conditions. Liquid fuel inlet A and fuel discharge outlet C, as can be seen in the drawings, are defined by oppositely disposed, outwardly extending

tubular bosses

24 and 26, respectively. lEach of the

bosses

24 and 26 is tapped to permit easy connection thereto of

tubes

12 and 14 respectively. The upper extremity of body Q terminates in a fiat ring-shaped surface 28 that contacts the outer circumferentially extending lower face of diaphragm L. A recess 27 is formed in the body Q within the confines of surface 28, and recess 27 is in communication with bore 20 and bypass O. 1

Spring housing U is preferably formed as an integral unit and comprises an inverted cup-shaped portion of a suitable rigid material 30, the lower end of which terminates in an outwardly extending ring-shaped liange 32 in which a number of circumferentially spaced bores 34 are formed. Bores 34 lare alignable with a like number of tapped bores 36 that extend downwardly into body Q from face 28. Wehn bores 34 and 36 are engaged by a number of screws 38 they cooperate to removably maintain housing U on body Q with diaphragm L gripped therebetween. The lower interior portion of housing U defines a ring-shaped recess 40 that engages the outer circumferential edge portion of backing disc T.

Backing disc T includes a circular plate 42 having a centrally disposed recess 44 extending upwardly therein from the lower face thereof. A tubular guide 46 extends upwardly from plate 42. A bore 46a formed in guide 46 is in communication fwith recess 44. 'Ihe valve plunger W is defined by a plate 48 disposable in recess 44, and a rigid protuberance 50 that extends upwardly therefrom to terminate in a convex end portion 52.

Spring guide V is preferably formed as an integral unit to define a short cylindrical side wall 54 which is closed on one end by a heavy wall 56, and on the opposite end portion has a circular flange 58 projecting therefrom. The lower surface of flange 58 rests ,on the upper surface of plate 42 when valve member M is in the position shown in FIGURE 2. The upper end of compression spring H abuts against the interior end surface of housing 30, and the lower end thereof presses against the upper surface of flange 58.

Valve member M is generally elongate in configuration-,5,

inwardly to an intermediately disposed' section 62, which" on its lower end develops into an enlarged conical portion 64 that is adapted to effect a fluid-tight seal with seat R when valve member M is in the position shown in FIGURE 2.

The upper end of spring N abuts against a ring-shaped surface 66 formed below conical portion 64, from which a second valve portion 68 depends that defines a fiat lower face 70 adapted to provide a fluid-tight seal with seat Z within contact therewith. The lower end of spring N rests against the orifice defining member Y. Seat Z is defined by an upper ring-shaped surface formed on a boss 72 comprising a part of orifice defining member Y. Member Y has an upwardly and inwardly tapering bo're 74 formed therein in which an insert 76 can be removably disposed. A plurality of inserts 76 may be provided, each of which have a bore 78 of different transverse cross section extending therethrough. By experimentation, the proper insert 76 having a bore 78 of correct size suitable for a particular liquefied petroleum gas fuel and known operating conditions can be determined.

The method of using the above described invention has been previously described in detail and need not be repeated.

From an operational standpoint the above described valve has the advantage that diaphragm L serves solely as a sealing medium and as a means to transfer the force of the compressed spring H to the plate 48, as well as the force exerted by fuel in chamber P to plate 48. A further advantage of the invention is that the plate 48 at all times moves on a longitudinal axis extending through the body Q and spring H, and at all times normal thereto.

It will be obvious to those skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof, and therefore the invention is` not limited by that which is shown in the drawing and described in the specification, but only as indicated in the appended claims.

I claim:

l. A valve for use in automatically supplying fuel to an engine at a substantially constant pressure from a storage tank that contains liquefied petroleum gas fuel and is subjected to varying ambient temperatures above that temperature at which said liqueed fuel would boil at atmospheric pressure, comprising: an elongate valve body having yliquid and vapor inlet passages formed therein that are in communication with said liquid fuel and the vapor thereof in said tank, as well as a common outlet for said liquid and vapor fuel that is in communication with said engine; a valve member sealingly and movably mounted in a rst bore in said body, said member being capable of occupying either a first position wherein communication is effected between said liquid inlet and said outlet or a second position wherein communication is effected between said vapor inlet and said outlet, with a portion of said valve member being so shaped that it cooperates with said first bore to define an annultis-shaped space that extends from a communicating position with said liquid inlet to a recess formed on the exterior of said body, which body has a second bore formed therein that extends from said recess to said outlet, together with liquid bypass means therein that includes said annulus-shaped space, said second bore, and said recess, with said means at all times connecting said inlet and said outlet; pressure-receiving means on said valve member that are at all times subjected to the pressure of said liquid in said bypass means for exerting a flrst force on said valve member in a direction to move said valve member to said second position where said vapor iiows from said outlet and said fuel in said tank is cooled by self-refrigeration as addi- 7 portions of saidfuelvaporizesto replace said vapor flows throughA said vapor inlet, said pressure-receiving meansv including arrigid plate aixed to a part ofsaid valve member that extends from said body and a resilient diaphragm sealingly aixed to said plate and that part of said body surrounding said recess; and spring means for exerting a second, torce on said valve member in a direction to overcome said tirst force and move said valve member to said first position where said liquid ows from said outlet without cooling when said liquid in said tank has been cooled toy the extent that the pressure of the vapor thereof starts to fall below said substantially constant pressure and said rst force overcomes said second force to move said valve member to said second position when the pressure on said liquid in said bypass means rises above said constant pressure due to an increase in temperature of said liquid in said tank 'as a result of absorption of heat from said ambient atmosphere.

2. A valve body as defined in claim l wherein a backing disc is provided that has a centrally disposed recess formed therein of such depth and transverse cross section as to permit said plate to fit snugly therein, said disc being provided with a rigid tubular guide in communication with said plate-receiving recess, said guide having a portion, of said valve member slidably disposed therein, with the upper extremity of. said valve member projecting upwardly therefrom,l with; means being provided to hold said, backing plate. in a position relative tosaid body that the circumferential surface portions of said diaphragm are gripped therebetween, and said diaphragm being so resilient that said rst force is only transferred through that portion thereofA in contact with said plate, with said. diaphragm lying in as'mgle. plane abutting against. at least portions of the surfaces of said plate and disc when. said valvemember is in said second position.

References Cited in the le of this patent UNITED STATES PATENTS 2,044,443 Ott June '16', 1936f 2,226,810 Ensign Dec. 3l, 1940 2,365,423 Macsporran Dec. 19, 1944 2,645,906 Ryan July 21, 1953' 2,719,518 Newman Oct. 4, 1955 2,757,516 Buttolph Aug. 7, 1956'.