US2675793A

US2675793A - Vapor-liquid selector valve

Info

Publication number: US2675793A
Authority: US
Publication date: 1954-04-20
Anticipated expiration: 1971-04-20

Description

April 20, 1954 N. E. ZIEGE 2,675,793

VAPOR-LIQUID SELECTOR VALVE Filed Dec. 26, 1951 un. lL-n INVENTOR. N. E. ZIEGE A TTORNEVS Patented Apr. 20, 1954 VAPOR-LIQUID SELECTOR VALVE Norman E; Ziege, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application December 26, 1951, Serial No. 263,219

9 Claims. l

This invention relates to internal combustion engine operation. In one aspect it relates to an improved apparatus for use with liquefied propane as an internal combustion engine fuel. In another aspect it relates to a liquid-vapor selector valve for use with liquefied petroleum gas fuel systems, in which valve liquid and vapor are selected alternately in response to temperature Within the fuel tank.

An object of this invention is to devise an apparat-.us for controlling the pressure of liquefied propane in internal combustion engine fuel tanks when the engine is powered with propane.

Another object of this invention is to devise an apparatus for use in maintaining relatively low pressures in liquefied propane fuel tanks under internal combustion engine operating temperatures.

Yet another object of my invention isto provide a liquid-vapor selector valve for use with liquefied petroleum gas fuel systems.

Still other objects and advantages of my invention will be realized upon reading the following disclosure.

The term propane as usedhereinbelow refers to commercial propane, and specifically to liqueed petroleum gas. This latter term includes, in addition to propane, such other hydrocarbons as butane, isobutane, isopentane and the like. When one or more of these less volatile hydrocarbons is included with propane in liquefied petroleum gas, the latter has correspondingly lower vapor pressures than propane.

Since the Vapor pressure of commercial propane is about 200 pounds per square inch at 100 F. the use of heavy pressure tanks as fuel tanks is necessary. At temperatures higher than 100 F., which temperatures are sometimes encountered during certain seasons of the year, propane has still higher vapor pressures than the above mentioned 200 pounds. lization of this liquefied fuel under such temperature and pressure conditions becomes a problem requiring careful solution.

In the prior art it is old to select liquid or gas Withdrawal from a tank by pressure responsive means selecting the gas withdrawal above a predetermined pressure and the liquid withdrawal below said predetermined pressure. Pressure responsive means are particularly sensitive to maladjustment and failure to operate properly after a relatively short period of time. The pressure at which they open soon varies widelyfrom the original predetermined pressure, which results in la dangerouscondtion and failure of their entire Thus, the utipurpose. In contrast, thermal responsive means does not change in long periods of time, but always acts at the same predetermined temperature even after years have passed. I have now discovered that temperature responsive means can accomplish the better results as to pressure control in liquid or gas withdrawal selection and continue to accomplish accurate control over much longer periods of time, with less servicing and adjustment, than direct pressure control. In accordance with the objects of my invention I have devised an apparatus which controls the alternate delivery of liquefied fuel, or vapor, from a tank in response to tank temperature, delivering vapor when the tank is above a predetermined temperature and delivering liquid when the tank is below said temperature.

In the drawing Figure l is an elevational View, partly in section, of a preferred embodiment of my invention. Figure 2 is van elevational view, in part, and partly in section, of another embodiment of my invention. Figure 3 is a diagrammatic representation of the apparatus of my invention as a portion of a complete internal combustion engine assembly.

Referring now to the drawing and specifically to Figure 1, this apparatus consists of a housing member II which has in general a circular cross section. The main or upper portion of this body member terminates as a lower cover plate 3l for a diaphragm assembly I3. This housing niemvloer I I has an axial opening throughout its length,

this opening being of different diameters in different sections. In the upper portion of the body member II the opening is of small diameter and accommodates a valve stem 3 I. Surrounding this valve stem in this small diameter opening is an O-ring seal 2l to prevent leakage of liquefied petroleum gas. At the lower end of this valve stem 3l is a valve head 2! which has provided on its upper surface a resilient sealing member 25. This resilient sealing member is intended to form a seal between the valve head and a valve seat 38. Biasing the valve 2| in a normally closed position is a compression spring 22. This compression spring is supported by a bushing member 23, which in turn is threaded and held in position by threads of a case member I5. This case I5 is threaded at 2d to the bottom portion of the housing member EI. The case I5 is provided on one side with a valve opening 20 .into whichis disposed a valve Il. A valve stem 33 of the valve Il is biased into a normally closed position by a compression spring I8. At a point diametrically across from the valve opening 20 is a thermo-responsive or thermostatic element I9. This element I9 is of a generally circular cross section with both ends closed with the exception of a small opening on one end into which is provided a push rod 32. tioned in contact with the end portion of the valve steml assembly 33 in such a manner that as the thermoresponsive element experiences an increase of temperature the push rod 32 moves from right to left thereby lifting the valve head |`I from its seat. Conversely, when the thermoresponsive element I9 experiences a decrease in temperature the compression spring I9 is intended to exert sufficient force tc seat the valve |'I and to push the push rod 32 from left to right. This thermo-responsive element I9 is provided with a semi-solid to solid thermo-expansive material mounted within a rigid shell.

The housing member I l is provided with a desirable weakness ring Id which of course is situated so that `in case of emergency the valve will break at this point while still permitting the valve head 2| to remain seated to prevent loss of high pressure fuei. Resting upon the top of the diaphragm I3 is a top Cover plate l2 provided with a vent tube 34. This vent tube 34 is intended to vent the space between the diaphragm I3 and the cover plate I2 to the atmosphere. Since this space is vented to the atmosphere it is obviously not necessary to use a gasket or other sealing means between the periphery of the cover plate and the top of the diaphragm. However, since the space below the diaphragm and above the lower cover plate 31 must be gas-tight a gasket 39 may be inserted between the top periphery of the cover plate 3l and the lower circiunference of the diaphragm I3 in such a manner that as the apparatus is assembled the tightening of the bolts holding the diaphragm in place will effect the proper seal.

On the bottom end of the case I5 is provided a liquid dip-tube IB, the lower end of which is intended to terminate in the liquid containing space of a LPG fuel tank in such a manner that liquid fuel may be drawn into the selector valve apparatus.

The threaded section 36 is intended to mesh with a corresponding threaded section of a fuel tank into which the assembly is installed for use. A tube 35 communicates'with the space below the diaphragm I3 and is intended to lead to the intake manifold of an internal combustion engine for-supplying vacuum to the underside Yof the diaphragm. A push lever 30 is provided as shown in contact with the underside of the diaphragm I3 Vand the upper end of the valve stem 3| in such a manner that when the pressure Yin space 4| is less than the pressure in space 59 the diaphragm I3 moves downward to force lever 3G downward and to open the valve 2|. When pressure in the space 4| is equal to or substantially equal to the pressure in space 4D the compression spring 22 is intended to bias the valve 2| against the seat 38 to close this Valve, which movement causes the upward movement of the lever 3B with the resultV that the diaphragm 3 is moved upward. The diaphragm I3 is intended to refer to an assembly including the diaphragm tended to carry fuel which passes the valve seat 38 to a conduit 28 and thence through the A threaded outlet 29 into a tube si (Figure 3) This push rod 32 is intended to be posi-V which conducts the fuel to the carburetion system.

The embodiment of my invention shown in Figure 2 is intended to illustrate the use of a similar thermo-responsive element as was used in relation to Figure 1 but with the element disposed in a vertical position. In this embodiment a thermo-responsive element 58 is held in its position -by a support member 69 which in turn is attached to the bottom of a case member 53. The case 53 is threaded at 54 to the bottom portion of a selector valve body member 5|. This body member 5| is in general similar to the body member of Figure 1 and the case 53 is intended to be more or less similar to the case I5 of Figure 1. Particular points of construction are however different than those involved in Figure 1. A fuel valve 'Z0 is provided with a resilient sealing member 1|, vhich is intended to seal against la valve seat 'I4 to open or to close the source of fuel tothe carburetion system. When fuel passes this valve Vseat 'I4 it flows through the space i3 and on through a conduit, not shown, to the carburetion system of an engine. A compression spring 69 held in position by a bushing member 65 biases the valve 'I6 into a normally closed position. This bushing 66 is threaded at 6'! to the main body member 5| as shown. This bushing 66 is provided With an opening $55 through which fuel may pass on its way tothe valve 7|). The lower end of the body member 5| is constructed so as to provide a valve seat I5 for use with a resilient sealing member El?. of the valve 63. A valve stem 59, which contains an axial opening 65, contacts at its lower end a thermo-responsive element 58. To one side of this hollow valve stem is attached a tube 6| which tube is termed a liquid dip-tube. This tube 6| serves the same function as tube I5 of Figure l. Attached to the valve stem '59 at a point within the case 53 is a spring rest member 62. This spring restrmember B2 is intended to serve as a support for a compression spring 5l which is intended to bias the valve 63 into a normally closed position with respect to the valve seat 15.

SomeV openings 55 are provided in the case 53 for inlet of gaseous fuel from the vaporspace-of the fuel tank into the selector valve apparatus. These openings 56 are of course provided inthe case 53 and at a point below the'main fuel valve lll. 1

A weakness ring 52 serves a similar purpose to the weakness ring I 4 of Figure 1. Threads 55 are intended to Ibe used in installing the selector valve apparatus of Figure 2 into a fuel tank. A valve stem 'i2 contacts the valve head 1|), as shown, and this stem extends upward through a small diameter opening vinto a space and into operative relation with a diaphragm similar to diaphragm assembly |3 of Figure-1', and not shown in Figure 2. Y Y

Figure 3-illustrates the installation of a selector valve of my invention in aninternaLcombustion engine apparatus. A'fuel tank 8| contains aV liquefied petroleum gas, fuel. This tank is provided witha selectorvalve of the type illustrated in Figure 1, preferably., and identified by reference numeral 82. Connected with Vthe threaded opening 29 isa conduit 8T for passage of fuel from the tank to a carburetor 85. This conduit 8l is provided with a constant pressure regulator valve 88. VThe conduit maybe provided with a V second constant pressure regulatorvalve 8,9 and tached to the lower side ofthe diaphragm case ofthe valve g2 and this conduit 99 is intended to be attached to the space below'the diaphragm and to a pressure reducinDr apparatus such as the intake manifold 86. The engine assembly is identified in Figure 3 by reference numeral 83, while the cooling system is identified by reference numeral Bil'.

For starting an internal combustion engine operating on liqueed petroleum gas and using the selector valve of Figure l, it is intended that upon pushing the starter of the engine a vacuum will be immediately created in the intake manifold. This Vacuum is transmitted through conduit 9i! of Figure 3 and through the tube connection 35 of Figure l into the space il below the diaphragm I3. This reduction of pressure in this space forces the diaphragm I 3 downward, which movement pushes the lever 3i?, valve stem 3l and opens valve 2l with respect to its seat 38. When this valve opens liquid or vapor fuel can pass the valve seat 38 and through conduits 25 and 23 and through threaded opening 29, all of Figure 1, and thence through the conduit 81 of Figure 3 to the carburetor. Assuming that the engine starts, this partial vacuum is maintained in the space il below the diaphragm and the valve 2| is therefore held in an open position to admit fuel continuously to 'the engine.

When a truck or bus or other automotive vehicle is on a highway under for example, summer time conditions, heat from the highway and from the summer sun may heat the fuel tank to such a temperature that the pressure of the propane will be increased to a pressure approaching the maximum safe operating pressure. According to my invention it is intended that when the temperature of the propane increases to a predetermined temperature value the thermo-responsive device i9 (Figure 1) operates to open the valve il and permit removal of this high pressure propane gas through the opening 29 and around valve 2l for use in the engine. Upon removal of propane gas, liquid propane evaporates in an attempt to reestablish pressure equilibrium in the fuel tank and this evaporation of liquid propane cools the remaining liquid due to the latent heat of evaporation. As long as the temperature within the fuel tank remains above a predetermined value the thermo-responsive element le holds the valve I'l open and permits removal of fuel vapor with the resultant evaporation of liquid fuel. When such a condition is reached that the liquid propane has been materially cooled or in other words when its temperature reaches a predetermined relatively low value the thermo-responsive element l G contracts and permits the compression spring I8 to close the valve Il. When valve il is closed liquid propane for fuel purposes is then withdrawn through the liquid dip-tube i6 and liquid accordingly passes the valve 2l and flows to the carburetion system.

As long as the temperature in the fuel tank remains below a predetermined temperature value the thermo-responsive element ES permits the valve I'l to remain closed, and, as explained above, when the temperature in the fuel tank rises to a predetermined value then the temperature responsive element ie again operates to open the valve il and permit the withdrawal of vaporous fuel which operation through evaporation of the liquid cools the contents of the tank. In this manner the pressure of the high vapor pressure fuel is held to a low and safe operating pressure.

The apparatus'illustrated in Figure 2 operates in substantially the same manner as does the apparatus of Figure 1. When the temperature of the contents of the fuel tank reaches a predetermined maximum temperature the thermoreponsive element 53 operates to raise the valve stem 59 and unseat the sealing member B4 from its seat l5. When this valve is unseated, vaporous fuel entering the case 53 through openings 56 is withdrawn through the valve E3 and thence is taken on through valve to the carburetion system. Similarly when the temperature within the tank has been decreased to a predetermined low value the thermo-responsive element 58 operates to permit the compression spring 51 to lclose the valve 63. When valve 63 is closed only liquid fuel maybe withdrawn through the liquid dip-tube 6I and through the hollow space 65 of the valve stem '59 for passage on through valve 'lil to the engine.

In the embodiments illustrated in Figures 1 and 2, it is intended that when the vapor valve l l of Figure 1 and the vapor valve 53 of Figure 2 are open vaporous fuel will flow in preference to liquid fuel due to the hydrostatic head of liquid fuel in the liquid dip-tubes l E and Bl. While this pressure may be small in terms of pounds or fractions of a pound, yet it is suiicient that when the vapor 'flow control valves are open, only or substantially only vapor will flow. However. if splashing of the liquid contents in the tank is caused from any reason it is immaterial whether liquid is withdrawn as fuel because as soon as this splashing effect subsides gaseous fuel will then be withdrawn. Such a condition would merely tend to retard the effective operation of the selector valve only momentarily.

Materials of construction of the apparatus of my invention may be selected from among those commercially available. Corrosion by such type of fuel is negligible.

While certain embodiments of my invention have been described for illustrative purposes the invention obviously is not limited thereto.

I claim:

l. A liquid-vapor selector valve assembly for use in liquefied petroleum gas fuel systems comprising, in combination, an elongated body member of generally circular cross section, a passageway throughout the length of said body member, the axis of said passageway coinciding with the axis of said body member, a valve having a head and a stem in said passageway for opening and closing said passageway to the flow of fluid, the axis of said valve coinciding with the axis of said body member, a compression spring biasing said valve in a normally closed position, a pressure operative diaphragm in operative contact with the stem of said valve and disposed in gas-tight relation with the upper end of said body member, a vented cover plate disposed above said diaphragm, a tube connection in said upper end of said body member and below said diaphragm, a sealing means in said passageway sealing the valve stem against leakage of fuel, a first opening in said body member providing communication from a point below said sealing means in said passageway with the exterior for outlet of fuel, a dip-tube attached to the bottom of said body member for admission of liquid fuel to said passageway, a port in the lower portion of said body member for admission of gaseous fuel to said passageway, a thermally operable valve for opening said port and a compression spring biasing said thermally operable valve in a normally closed position.

2. TheV selector 'valve assembly of claim 1 wherein the axis of the thermally operable valve is disposed normal to the axis of said elongated body member.

3. The selector valve assembly of claim 1 wherein the axis of the thermally operable valve coincides with axis of said elongated body member.

4. The selector valve assembly of claim 1 wherein said thermally operable valve opens upon increase of temperature of the thermally responsive element.

5. In the valve assembly of claim 4 wherein the thermally responsive element is a semi-solid to solid plastic material.

6. In a liqueed petroleum gas fuel system the improvement comprising a tank for storing liqueed petroleum gas fuel, a conduit for carrying said fuel from the tank to its point of useI a fuel now control valve disposed at least in part in said tank and connecting said conduit With said tank, a liquid dip-tube extending from said valve vto the liquid-containing space in said tank, a port in the Wall of said Valve inside said tank for transmitting vapor from the vapor space of said tank to said valve, a port valve having a head and a stem disposed in said tank and in operative relation to said port to open and to close same, the stem of said port valve being disposed at right angles to the axis of said fuel flow control valve, a compression spring biasing said port `valve in a normally closed position, and a semisolid to solid matter filled thermally expansive capsule in operative relation to the stem of said port valve, said capsule being so disposed as to open said port valve upon rise of temperature of said capsule.

'7. A volatile liquid fuel system for an internal combustion engine having an intake comprising a fuel tank, a fuel line connected in communication with said tank and said intake of said engine, a motor valve connected in said fuel line biased to close the same and controlling flow of fuel therethrough, said motor being connected by a vacuum line to said intake and responsive to partial vacuum in said intake to open said fuel line, a dip-tube in said tank for liquid withdrawal connected in communication with said fuel line, and a thermal motor valve biased to closed position connected in communication with the upper portion oi said tank and the interior of said dip-tube and controlling flow of vapor therebetween responsive to a predetermined temperature, said thermal motor opening said thermal motor Valve above a predetermined temperature.

8. The system of claim 7 wherein the axis of said thermal motor valve is normal to the axis of said dip-tube.

9. The system of claimv 7 wherein the axis of said thermal motor valve coincides with at least a portion of said dip-tube.

References Cited in the le of this patent UNITED STATES PATENTS Number