US2073282A - Volatile hydrocarbon vaporizing and fuel supply system - Google Patents

Description

March 9, 1937. c MCCARTNEY 2,073,282

VOLATILE HYDROCARBON VAPORIZING AND FUEL SUPPLY SYSTEM Original Filed April 26, 1932 Inventor Charles 15. me'tarhrey.

Patented Mar. 9, 1937 UNITED STATES PATENT OFFICE VOLATILE HYDROCARBON VAPORIZING AND FUEL SUPPLY SYSTEM Original application April 26, 1932, Serial No. 607,581. Divided and this application August 10, 1934, Serial No. 7

3 Claims.

This invention deals generally with fuel vaporizing and supply systems, and particularly with such systems utilized for feeding gaseous or vaporized fuel to internal combustion engines. The present application is divisional of my copending application, Ser. No. 607,581, filed April 26, 1932, on Carbureting apparatus.

Within comparatively recent years, a volatile hydrocarbon fuel consisting mainly of ethane, l propane and butane fractionshas come extensively into use for domestic heating and lighting purposes, and also as fuel for internal combustion engines. This fuel, being volatile at normal atmospheric temperatures, is handled and shipped 15 in pressure containers within which the fuel is confined at a pressure of around 50 to 60 lbs. per sq. in. gage, its vapor pressure at average atmospheric temperatures. Various difliculties have been encountered in attempting to utilize this 20 fuel for operating internal combustion engines,

by reason of its extreme volatility and the extreme cooling effect resulting from expansion of the liquid fuel vapor phase. The reason has been primarily that the volatile characteristics of the 25 fuel prevent its being satisfactorily vaporized and fed to the engine with known types of fuel supply or carbureting apparatus designed for the less volatile fuels, such as gasoline and heavier oils. It is accordingly my chief object to provide a 30 system for vaporizing and supplying under substantially constant pressure, vaporized fuel consisting essentially of ethane, propane and butane fractions, and in so doing to overcome the limitations of supply systems designed for heavier 35 fuels.

In accordance with the invention, the liquid fuel is taken from the pressure container to a heater wherein the fuel is substantially completely vaporized. However, instead of effecting 40 the entire vaporization by means of heat supplied to the heater, I accomplish a partial vaporization by dropping the fuel pressure at some suitable point between the pressure container and the heater, for reasons which will hereinafter appear 45 more fully. Then, after the fuel is completely vaporized in the heater, I preferably then again reduce the pressure of the fuel in a vapor line leading from the heater to a connection with a carbureter, engine manifold or other point of use. 50 The fuel pressure thus is reduced in two stages, from the second of which the fuel is fed at a constant and predetermined pressure, around or somewhat below atmospheric, depending upon the conditions of the installation.

The various aspects of the invention, as well as various features and objects, will be more fully understood from the following detailed description. For the purpose of setting forth a complete operative engine supply system, I will describe also a gas carbureter which meters the fuel flowing to the engine and which receives vaporized fuel from the system briefly described above. The scope of the present application, however, includes only the fuel supply system. Throughout the description, reference is had to the accompanying drawing, in which:

Figure 1 is a view, partially in vertical section, showing the fuel and air metering and mixing part of the apparatus;

Fig. 2 is a section on line 2-2 of Fig. 1;

Fig. 3 is a section on line 33 of Fig. 1, the outlet end of the mixing passage being shown in elevation;

Fig. 4 is a section on line 44 of Fig. 3; and

Fig. 5 is a fragmentary conventional elevation showing the apparatus in connection with an internal combustion engine, the fuel heater and vaporizer being shown in vertical section.

Referring first to Fig. 1, the fuel and air mixing part of the apparatus comprises a body, generally indicated at I 0, containing an air passage ll having an inlet l2 and an outlet l3. The latter connects with the engine manifold, as shown in Fig. 5, by way of pipe M, the flanged end Ila. of which is bolted to flange IS on the outlet end of the body 10. The body is made in two sections Ilia and lb attached together by means of bolts I6. Body section Illa contains a throttle l1, shown typically as a simple butterfly valve l'la carried on shaft Hi, the latter being operated by way of arm l9 and rod 20, see Fig. 5. An internal flange 2| is formed at the upper end of body section l 017, and opening through this flange is a pair of orifices 22 and 23, see Figs. 2 and 3, the former being comparatively large and passing air from inlet I2 to the outlet l3 orifice 23 being comparatively small and passing fuel 'from the fuel supply source, hereinafter described, into the air passage. Section Illa. also has an interior flange 25 forming an opening 26 registering with aperture 22, and being preferably of somewhat greater width as viewed in Fig. 1.

As a simple expedient for maintaining the relative sizes of the orifices substantially constant while allowing changes in their individual sizes, I form the orifices 22 and 23 rectangularly in shape, the widths of the orifices, in the direction of valve movement, being substantially uniform. Since the individual widths of the orifices in the direction of valve movement remain the same for all positions of the valve, it follows that the rela- 10 to control the passage of fuel and air through the orifices. As shown in Fig. 1, valve 32 in closed position overlaps flange 2| at the left to completely close both orifices. The valve extends through the side of the body and is connected as at 34 with a valve operating rod 35. As shown in Fig. 2, a diaphragm containing body 36 is supported on the body II) by means of members 31. Body 35 comprises a pair of hollow sections 35a and 36b between which a flexible diaphragm 38 2 is clamped. Rod 35 extends through section 36a and is attached to the diaphragm as shown. A spring is provided for exerting a constant closing force on the valve, the spring being of a constant tension type comprising a pair of resilient bows 40 caried on nut 4i and bearing against the dia-- phragm case. Nut 4! is threaded on rod 35 and is therefore capable of longitudinal adjustment to regulate the tension of the spring, lock nut 42 holding the spring carrying nut in adjusted position.

Chamber 43 within the diaphragm body section 361; is connected with the air passage I l at a point between valve 32 and the throttle, by way of tube 44. The function of tube 44 is to communicate to the diaphragm the pressure within portion lid of the air passage between the throttle and orifice control valve, and to allow the diaphragm to move in response to variations in pressure at iia. At closed position of the throttle, the pressure in I la will more closely approach that of the atmosphere, at which time no substantial depression may be communicated to the diaphragm. Valve 32 will therefore remain in closed position under the influence of spring 40. Upon opening movement of the throttle, the manifold suction or depression is communicated past the throttle to space a and thence through tube 44 to the diaphragm, causing the diaphragm to deflect to such position as shown in Fig. 2, and valve 32 to open.

If it be assumed that with the parts in the positions shown in the drawing, the engine is operating at a medium speed, the immediate effect produced by opening the throttle to accelerate the engine, will be to create a temporarily increased depression in Ha, which depression is communicated to the diaphragm to cause valve 32 to open wider. Opening movement of the valve, however, increases the size of the air passing orifice, so that the depression in Ila returns to its normal value. The converse of these operations, of course, occurs upon closing movement of the throttle, retardation of the engine speed resulting in the maintenance, after uniform operating conditions have become established, of the same constant depression in Ha.

The fuel feed system with which the invention is more particularly concerned is shown inFig. 5, and is provided for the purpose of converting the highly volatile liquid fuel to vapor, and for supplying the vaporized fuel to the fuel mixing apparatus at substantially constant predetermined pressure. The apparatus is shown to be attached to an engine 45 supplied with fuel from a tank 41, the latter containing volatile liquid hydrocarbon under its normal vapor pressure at the existing temperature conditions. Fuel is fed from the tank 41 through line 43 to a heater generally indicated at 49, there being a pressure reducing valve 50 placed in the line between the tank and heater. In the broader aspects of the invention, any suitable apparatus may be provided for heating and vaporizing the fuel. As typical of such apparatus, I have shown a shell '5l containing a coil 52 connecting with line 43 and communicating through pipes 53 and 30 with space 23 and the fuel supply orifice in body III. A pressure reducing valve 54 is also placed between lines 53 and 30. Coil 52 within shell may be heated by any suitable means, as for example by water from the engine radiator 55 circulated through the shell by way of pipes 56 and 51.

The pressure in tank 41 and line 48 up to the pressure reducing valve 50, will be determined in accordance with the vapor pressure of the fuel. Using a fuel consisting of such low boiling fractions as ethane, propane and butane, the

pressure in tank 41 maybe in the neighborhood of 60 lbs. per square inch gage. Valve 50 preferably will be set to reduce the pressure in the heating coil to in the neighborhood of 5 lbs. per square inch gage, thereby bringing about a certain amount of vaporization by virtue of the pressure reduction alone. In the heater, the fuel is converted entirely to vapor which passes through lines 53 and 30 to the fuel supply orifice. Pressure reducing valve 54 is set to maintain a constant pressure on the fuel being supplied to orifice 23, this pressure being comparatively low and in the neighborhood of say from minus 2 to minus 5 inches of water, gage pressure.

Particular advantages are gained by the installation of pressure reducing valve 50 at the inlet side of the heater, and also by the provision of the two pressure reducing valves at opposite sides of the heater. Difflculties in starting operations that would otherwise occur, are obviated by subjecting the high volatile liquid fuel to an initial pressure drop before entering the heater. In the absence of valve 50, before the engine is started and before the fuel heater is brought up to normal temperature, the fuel filling pipes 48, 53 and the heater coil 52, would for the most part be liquid. Then, as the engine is started, a pressure drop from substantially tank pressure to some pressure around atmospheric would occur at valve 54, and by reason of the comparatively great pressure differential, there would result a corresponding cooling eifect and rapid accumulation of frost on and freezing within valve 54. By providing valve 50, and thereby taking the total pressure drop in two stages, sufiicient volatilization may take place at the expansion side of this valve that even at low starting temperature conditions within the heater, ample vaporized fuel will be fed to the engine until temperature conditions throughout the system are brought up to normal.

I prefer to use engine circulating water as the heating medium for the reason that, normally, the water is comparatively uniform in temperature, and for that reason conditions of corresponding uniformity are maintained within the fuel vaporizing and supply system. Moreover, it is assured that under no conditions will the temperatures in the heater exceed the boiling temperature of water, a matter of importance considering the extreme volatile characteristics of the fuel.

From the foregoing, it will be seen that the system operates to supply vaporized fuel at a constant predetermined pressure. If for any reason it becomes desirable to vary the fuel richness in the combustible mixture being fed to the engine, such variations may be accomplished by varying the pressure of fuel fed to the fuel passing orifice through regulation of valve 54, the latter being of any well known type capable of adjustment, as by means of lever 54a.

I claim:

1. In apparatus for supplying gaseous fuel to an engine via a throttle controlled carbureter suction passage into which the fuel is drawn through a fuel inlet in accordance with the depression existing in said passage; the combination comprising, a pressure container for fuel that is volatile at atmospheric temperatures and pressure, a heater for heating and vaporizing the liquid fuel, a fuel supply line connecting said container with the heater, a pressure reducing valve in said line operating to substantially reduce the pressure of the fuel being fed to the heater, a vapor line leading from said heater to the carbureter fuel inlet, and a pressure reducing valve in said vapor line operating to deliver fuel to said fuel inlet at substantially constant pressure.

2. In apparatus for supplying gaseous fuel to an engine via a throttle controlled carbureter suction passage into which the fuel is drawn through a fuel inlet in accordance with the depression existing in said passage; the combination comprising, a pressure container for fuel that is volatile at atmospheric temperatures and pressure, a heater for heating and vaporizing the liquid fuel, a fuel supply line connecting said container with the heater, a pressure reducing valve in said line operating to substantially reduce the pressure of the fuel being fed to the heater, a vapor line leading from said heater to the carbureter fuel inlet, and a pressure reducing valve in said vapor line operating to deliver fuel to said fuel inlet at substantially constant subatmospheric pressure.

3. In apparatus for supplying gaseous fuel to an engine via a throttle controlled carbureter suction passage into which the fuel is drawn through a fuel inlet in accordance with the depression existing in said passage; the combination comprising, a pressure container for fuel that is volatile at atmospheric temperatures and pressure, a heater for heating and vaporizing the liquid fuel, a fuel supply line connecting said container with the heater, a pressure reducing valve in said line operating to partially vaporize and substantially reduce the pressure of the fuel being fed to the heater, a vapor line leading from said heater to the carbureter fuel inlet, and a pressure reducing valve in said vapor line operating to deliver fuel to said fuel inlet at substantially constant subatmospheric pressure, the first mentioned pressure reducing valve being set to reduce the fuel pressure through a substantially greater differential than the last mentioned valv CHARLES E. McCARTNEY.

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