Fuel supply system

An apparatus for supplying aerosol fuel particles uniformly mixed with air to utilizer, as an internal combustion engine or burner. The apparatus has several fuel mixing and atomizing nozzles operable to mix one or more liquid hydrocarbon fuels and discharge the fuels through orifices in small fuel particles of uniform size. The fuel particles are mixed with air and flow through a pair of venturi throats with converging inlet walls and diverging outlet walls. The velocity of the air and fuel particles flowing through the venturi throats is at or above the speed of sound. The fuel particles are finely divided into particles between 0.5 and 1.5 micron in diameter as they move through the turbulent inlet and outlet interfaces of the air flowing through the nozzle throats at sonic and supersonic velocities and are evenly distributed into the air. The length or major dimension of one of the venturi throats is regulated with a baffle in accordance with the speed requirements of the engine.

BACKGROUND OF INVENTION 
Emissions from conventional internal combustion gasoline engines are formed 
when hydrocarbon fuel, as gasoline, is burned incompletely into 
hydrocarbon (HC) and carbon oxides (CO). The formation of pollutant CO, HC 
and nitrous oxide (NO.sub.x) is a function of the proportional amounts of 
air and fuel introduced into the combustion chamber. The effect of the 
air-to-fuel ratio on the exhaust combustion of these pollutants is shown 
in the graph of FIG. 1. Lean air-to-fuel ratios have decreased CO and HC 
emissions because of the greater quantity of oxygen available for 
combustion. When the air-to-fuel ratio becomes too lean (below 14:1), both 
HC and CO emissions increase. 
NO.sub.x emissions are an exponential function of flame temperature. At low 
temperatures, nitrogen and oxygen will not unite to form any significant 
amount of NO.sub.x. Low temperatures are achieved at both rich and lean 
air-to-fuel ratios because of the dilutant effect exerted by unburned fuel 
in the rich case and the excess of air in the lean case. 
When the internal combustion engine operates at its stiochiometric point, 
the amount of fuel is matched exactly with the amount of oxygen for 
complete combustion. This point falls somewhere between 14.5 and 15 pounds 
of air per pound of fuel. The operation of an engine at this point 
produces the maximum amount of NO.sub.x. An air-to-fuel mixture of 18-20 
pounds of air per pound of fuel will produce the least CO, HC and NO.sub.x 
emissions. 
Internal combustion engines will operate effectively at air-to-fuel ratios 
of 18:1 or even leaner ratios. The operation of the engine under these 
conditions is contingent on getting the right air-to-fuel mixture into all 
of the cylinders. With present carburetor technology, the air-to-fuel 
ratio of the fuel mixture to all of the cylinders is not constant. Some of 
the cylinders will be fed properly while others will be too lean. Others 
may be too rich. In either circumstance, there will be an increase in 
emissions. 
Hydrocarbon fuels have a small percentage of foreign liquids and 
particulate matter, as water, oils, non-combustible carbon, and dirt. 
These foreign products cause dirt build-up in the carburetor and 
inefficient fuel-to-air ratios. 
Hydrocarbon fuel vapor and air mixing devices have been developed. These 
devices have structures for heating or elevating the temperature of the 
fuel prior to the release to the intake manifold of the engine. Examples 
of fuel vaporizing and air mixing devices are shown in U.S. Pat. Nos. 
3,509,859; 3,847,128 and 3,872,848. 
High frequency ultrasonic generators having piezoelectric ceramic crystals 
have been used for ultrasonic cleaning operations and in the material 
testing field. Other applications include medical and chemical uses for 
emulsifying and dissolving purposes. Examples of high frequency ultrasonic 
generators are shown by Scarpa in U.S. Pat. No. 3,433,161 and Rodudo et al 
in U.S. Pat. No. 3,904,347. 
A monodisperse aerosol generator is disclosed by Berglund and Liu in U.S. 
Pat. No. 3,790,079. This generator has an ultrasonic vibrator that acts on 
a disc having a discharge orifice. The liquid moving through the orifice 
is subjected to ultrasonic vibrations which break the liquid down to 
substantially equal size droplets which are discharged into a chamber. 
SUMMARY OF THE INVENTION 
The invention is broadly directed to an apparatus and method for providing 
a lean air-to-fuel mixture to a utilizer, as an internal combustion engine 
or burner, where the fuel is environmentally and economically used to 
produce output power or heat. The invention is embodied in an apparatus 
which utilizes a liquid hydrocarbon fuel and converts the liquid fuel into 
an aerosol that is uniformly mixed with air prior to its consumption by 
the utilizer. The apparatus has nebulizers or ultrasonic generators that 
receive hydrocarbon fuel under pressure. The nebulizers have ultrasonic 
generating means that are operable to mix a number of different 
hydrocarbon fuels with each other and with other substances, as water, 
oils, dirt, and carbon. The nebulizers also discharge the hydrocarbon fuel 
in small and substantially uniform particles. The fuel particles are moved 
with incoming air through a sonic nozzle. The sonic nozzle has a pair of 
converging and diverging throats. One of the throats is an idle throat and 
the other is a variable size or run throat. The uniform sized liquid fuel 
particles discharged by the nebulizers are carried by the air stream 
through the venturi throats. As the air and particles approach the venturi 
throats, there is a first turbulent inlet interface caused by the rapid 
acceleration of the air. The air accelerates to a sonic or supersonic 
speed. A second or outlet interface is experienced as the air and 
particles leave the venturi throat. The second interface is the result of 
rapid deceleration of the air to subsonic speeds. As the air and particles 
move through the acceleration interface and deceleration interface, there 
is a thorough and rapid breakdown and mixing of the fuel particles with 
the air. The fuel particles break down into sizes of 1 micron or less in 
diameter and are evenly distributed with the air. The result is a uniform 
air-to-fuel ratio which is delivered to the utilizer, such as the 
combustion chamber of an engine. The fuel and air mixture can also be 
delivered to the combustion chamber of a burner. The sonic nozzle has a 
control baffle for regulating the flow of air through the run throat. The 
baffle is used to increase and decrease the size of the throat in 
accordance with the desired speed of the engine. A control moves the 
baffle along the length or major dimension of the throat. The width of the 
throat is constant. The sonic flow of air through the venturi throats 
depends upon the upstream pressure and temperature of the air. The amount 
of vacuum or suction pressure on the outlet side has only a minimal effect 
on the amount of air and fuel that move through the venturi throats. The 
quantity of air and fuel moving through the throats is directly 
proportional to the throat area. The fuel pump for the nebulizers are 
coordinated with the controls for the baffle so that the fuel dispensed by 
the nebulizers is in proportion to the size of the venturi throats. 
An object of the invention is to provide a fuel supply system for an 
internal combustion engine or burner that is operable to uniformly mix one 
or more hydrocarbon fuels and discharge the mixed fuel into substantially 
uniform, finely divided particles into an air stream. Another object of 
the invention is to provide a fuel system for an internal combustion 
engine operable to provide substantially uniform size fuel particles that 
are evenly distributed in air to form an air-to-fuel ratio that has a 
minimum of HC, CO and NO.sub.x emissions when burned in an engine. A 
further object of the invention is to provide a fuel supply system that 
produces a high air-to-fuel ratio of uniform consistency that burns clean 
in high compression engines. Yet another object of the invention is to 
provide a sonic nozzle operable to finely divide liquid hydrocarbon fuel 
particles into fuel particles having a diameter in the range of 0.5 to 1.5 
micron. A still further object of the invention is to provide a fuel 
system for a utilizer, as an internal combustion engine or burner, that 
can uniformly mix a number of different fuels into a mixture that is 
usable in a combustion environment. Yet another object of the invention is 
to provide a liquid fuel discharge structure with ultrasonic vibration 
means that mixes liquid fuel with foreign materials and is self cleaning 
in operation. Another object of the invention is to provide a sonic nozzle 
with a pair of venturi throats that maintains supersonic air flow 
conditions over a wide range of engine speeds. These and other objects and 
advantages of the invention will become apparent from the following 
detailed description of the fuel supply system.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to the drawing, there is shown in FIG. 2 a fuel supply system 
indicated generally at 10 operable to receive a liquid hydrocarbon fuel, 
as gasoline, disel fuel, methanol, or the like, from a fuel supply 11 and 
deliver the liquid fuel as an aerosol appropriately mixed with air to a 
utilizer 12, as an engine or burner. Preferably, the liquid fuel in 
aerosol form is mixed with air at a fuel-to-air ratio of about 18:1 so as 
to produce the least emissions by engine 12. The fuel supply system 10 has 
a pair of nebulizers or ultrasonic generators 13 and 14 connected to fuel 
supply 11 with lines 16 and 17. A pump 18 moves the fuel from supply 11 
under pressure to the nebulizers. Additional nebulizers as nebulizer 15 
shown in FIG. 3, can be used. 
Nebulizers 13 and 14 are operable to discharge liquid fuel particles 
indicated by arrows 19 into a sonic nozzle 21. The nebulizers 13 and 14 
function to mix the fuel and discharge the fuel in an aerosol form having 
a uniform particle size in the range of about 1 micron or less in 
diameter. 
Sonic nozzle 21 is connected to a control 22. Control 22 is operable to 
regulate the flow of air and fuel particles through the nozzle in a manner 
such that the air flowing through portions of the nozzle is always at a 
sonic or supersonic speed. Sonic nozzle 21 has two extremely turbulent 
interfaces which provide for thorough and uniform mixing of the aerosol 
fuel with the air. The fuel particles are further reduced in size as they 
pass through inlet and outlet interfaces. The first interface is when the 
air and fuel are accelerated from a subsonic to supersonic speed as the 
air moves through the venturi throats of the nozzle. The second interface 
is encountered when the air and fuel particles decelerate from a 
supersonic speed to a subsonic speed. The mixed fuel is then delivered to 
the engine, as shown by arrow 23. 
Referring to FIG. 3, fuel supply system 10 has an air and fuel treatment 
assembly indicated generally at 24 mounted on an intake manifold 25 of an 
internal combustion engine. Manifold 25 is illustrated as being connected 
to four separate cylinders and functions to deliver air and fuel to the 
cylinders. The number of cylinders of the engine can vary. Assembly 24 can 
be mounted on a burner. Assembly 24 has a rectangular housing indicated 
generally at 26. As shown in FIG. 5, housing 26 has elongated parallel 
side walls 27 and 28 connected to end walls 29 and 31. Walls 27, 28, 29 
and 31 form a generally rectangular passage 32 through housing 26. As 
shown in FIGS. 4 and 5, side walls 27 and 28 have outwardly directed 
bottom flanges 27A and 28A respectively. Suitable fastening means 33, as 
bolts, shown in FIG. 3 are used to secure the side walls to manifold 25. 
Referring to FIG. 4, nebulizer 13 has a body 34 located in the central 
portion of passage 32. Body 32 has an internal chamber 36 and a neck 37 
attached to the side wall 28. A passage 38 extended through neck 37 is in 
communication with the fuel line 17. Nuts 39 and 41 threaded on neck 37 
secure body 34 to side wall 28. The lower end of body 34 has an annular 
flange 42 having a recess accommodating a toroidal washer 43. Washer 43 
has a thin annular neck or collar 44 to minimize the transfer of the 
vibrations of the center portion of the washer 43 to body 34. A generally 
cup-shaped cover or cap 46 is threaded onto body 34 to clamp the washer 43 
to body 34. Cover 46 has a bottom with a central opening 47 allowing the 
fuel particles to be dispensed into passage 32. 
Located within cover 46 is a head or cup member 48 having a longitudinal 
chamber 49. The upper end of chamber 49 is in communication with chamber 
36. Member 48 is located in the central opening and threaded on washer 43. 
The bottom of member 48 has a hole or orifice 52 in longitudinal alignment 
with hole 47. Member 48 can have additional orifices similar to orifice 
52. 
A vibrating means 53 surrounds the cup-shaped member 48 and is operable to 
impart high frequency ultrasonic vibrations to member 48 and the liquid 
fuel located in chambers 36 and 49. Vibrating means 53 mixes the 
hydrocarbon fuels with impurities in the fuels. The vibrations or 
vibratory forces on the liquid fuel also has a self-cleaning effect on 
member 48 and its orifice 52. The sonic vibrations are at frequencies 
exceeding a megacycle. Other sonic vibration frequencies can be used to 
achieve the mixing, breakdown and self-cleaning characteristics caused by 
vibrating means 53. Vibrating means 53 is a ceramic collar as a tube of 
piezoelectric ceramic material as, for example, barium titanate zirconate. 
The collar surrounds the side wall of member 48 and is attached thereto. 
The ceramic collar has inner and outer electrode coatings or films 54 and 
56 aplied to its inner and outer surfaces respectively. Tube 61 is 
processed and treated to vibrate in a principal resonant thickness mode. 
The nebulizers or ultrasonic generators 14 and 15 have the same structure 
as shown by nebulizer 13 in FIG. 4. All of the electrode coatings on the 
ceramic tubes 53 are connected to a high voltage source 55. Other types of 
vibrating structures can be used to vibrate member 48 and the liquid fuel. 
Sonic nozzle 21 has a first side wall 58 secured to the inside of wall 27 
and a second side wall 61 secured to the inside of wall 28. Side wall 28 
has a convex curved surface 59. Side wall 61 has a similar inwardly 
directed convex surface 62. The space between surfaces 59 and 62 is 
separated with an elongated divider 63. Opposite ends of the divider are 
secured to the end walls 29 and 31. Divider 63 has a generally tear-shaped 
cross section with outside convex surfaces 64 and 66. The surface 64 faces 
surface 59 and is spaced from the surface 59 to form an elongated idler 
venturi throat 67. The surface 66 is spaced from the convex surface 62 to 
form a variable size or run venturi throat 68. The throat 68 has about 
twice the width of throat 67. Throats 67 and 68 have the same length. 
Other width relationships between the throats 67 and 68 may be used. 
The length or major dimension of throat 68 through which air and fuel can 
flow is regulated with a slide valve or plate 69. The plate 69 is a baffle 
slidably mounted on side wall 26 and the top of divider 63. The bottom 
side of plate 69 has an elongated linear groove 71 slidably mounted on an 
upwardly directed rib 72 on the top of divider 63. Wall 26 has a groove 73 
for accommodating an edge of plate 67. The plate 69 extends through a 
suitable hole in end wall 63 so that it can be linearly moved to adjust 
the length of throat 68. Throat 68 has a fixed and uniform width or minor 
dimension. The length of throat 68 is changed by movement of plate 67 
without changing its width. 
The control for moving the plate 69 comprises a pivoted lever 74 mounted on 
a pivot structure 76. The midportion of lever 74 is connected to a link 77 
with a pivot 78. The opposite end of link 77 is connected with a pivot 
structure 79 to plate 69. An actuator 81 is connected to the upper end of 
lever 74. Actuator 81 is movable to pivot lever 74, as indicated by arrow 
82, and thereby move the plate 69 into and out of the housing 26, thereby 
adjusting the size of the venturi throat 68. Other types of controls can 
be used to move plate 69. 
In use, with the engine idling, plate 69 is moved to its in or closed 
position, completely closing the venturi throat 68. All of the air and 
fuel moving through the sonic nozzle 21 moves through the idler throat 67. 
The air moves through the venturi throat 67 and into the intake manifold 
and engine. The nebulizers 13, 14 and 15 receive fuel under pressure from 
the pump 18. The pressurized fuel is discharged through opening 52 into 
the air moving through passage 32. Vibrating means 53, being subjected to 
a high voltage power, vibrates the fuel to mix the fuel in chamber and 
vibrates the orifice 52. The frequency of vibration of the member 48 is in 
the megacycle range which atomizes the liquid fuel as it is discharged 
through nozzle 52 in relatively small and uniform fuel particles. 
Preferably, the particle size is between 0.5 and 1.5 microns in diameter. 
The atomized fuel is mixed with air in passage 32. As the mixed air and 
fuel approach the venturi throat 67, the fuel and air pass through an 
inlet interface at the entrance to the venturi throat. This interface is 
caused by the rapid acceleration of the air to a sonic and supersonic 
speed. In the interface area, the fuel particles in the air are thoroughly 
integrated and reduced in size. The fuel and air pass through the venturi 
throat 67 and discharged to the lower section 32A of the passage 32. The 
fuel passes through a second deceleration interface. As soon as the fuel 
and air leave the venturi throat 67, there is rapid deceleration of the 
flow of fuel to a subsonic flow. This causes further size reduction and 
uniform mixing of the air and fuel before it enters the manifold 25. 
The speed of the engine is increased by moving the plate 69 to an open 
position. FIG. 4 shows plate 69 open to aproximately half of full speed, 
exposing a portion of the venturi throat 68. The size of the venturi 
throats 67 and 68 are coordinated with the size of the engine, that is, 
the amount of air required by the engine to operate at various speeds is 
correlated with the sonic flow of air through the venturi throats 67 and 
68. As the air and fuel pass through venturi throat 68, they pass through 
acceleration and deceleration interfaces to thoroughly mix the particles 
with the air. The pump 18 has a control 83 which is coordinated with the 
actuator rod 81 so that the amount of fuel supplied to the nebulizers 13, 
14 and 15 is in accordance with the fuel requirements of the air flowing 
through the venturi throats 67 and 68. 
Referring to FIG. 7, there is shown a modification of the fuel supply 
system of the invention indicated generally at 100. System 100 has a 
hydrocarbon fuel supply 111 connected to an ultrasonic nebulizer 113. The 
fuel is withdrawn from the nebulizer 113 with a pump 118. The pump 
delivers the fuel to a sonic nozzle 121. A plurality of discharge 
structures 122 having orifices dispense a spray of fuel to the sonic 
nozzle 121. The sonic nozzle 121 is mounted on an engine or burner and 
functions to deliver mixed air and fuel to the utilizer 112. Nebulizer 113 
is identical in structure to nebulizer 13 shown in FIG. 4. The sonic 
nozzle 121 follows the sonic nozzle structure shown in FIGS. 4 and 6. 
The fuel supply 111 can be a single hydrocarbon fuel or a number of 
different hydrocarbon fuels. The plurality of fuels are mixed in the 
ultrasonic nebulizer. The mixed fuel is delivered to the pump which 
discharges the mixed fuel into the sonic nozzle. The sonic nozzle breaks 
the fuel down into atomized form and mixes the fuel with air. The mixture 
of fuel and air is delivered to the engine or burner. 
Several preferred embodiments of the invention have been shown and 
described. It is understood that various changes and modifications can be 
made by those skilled in the art without departing from the invention.