U.S. patent application number 11/817785 was filed with the patent office on 2008-08-14 for vapor fueled engine.
Invention is credited to Raymond Bryce Bushnell, Danny Robert Lewis.
Application Number | 20080190400 11/817785 |
Document ID | / |
Family ID | 36953684 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080190400 |
Kind Code |
A1 |
Bushnell; Raymond Bryce ; et
al. |
August 14, 2008 |
Vapor Fueled Engine
Abstract
A fuel supply assembly providing vaporized fuel to an engine
wherein a quantity of liquid gasoline fuel is controllably heated
for a desired vapor emission from the liquid fuel, and a conduit
arrangement conducts the vapor, intermixes it with ambient air and
conveys the intermixture to the engine's combustion chamber. A
sensor in the engine exhaust monitors the hydrocarbon content of
the exhaust and control valving controls the vapor to air
intermixture in response to the monitor for maintaining a desired
intermixture that produces the desired hydrocarbon content.
Inventors: |
Bushnell; Raymond Bryce;
(Beavercreek, OR) ; Lewis; Danny Robert;
(Beavercreek, OR) |
Correspondence
Address: |
SCHWABE, WILLIAMSON & WYATT, P.C.;PACWEST CENTER, SUITE 1900
1211 SW FIFTH AVENUE
PORTLAND
OR
97204
US
|
Family ID: |
36953684 |
Appl. No.: |
11/817785 |
Filed: |
September 30, 2005 |
PCT Filed: |
September 30, 2005 |
PCT NO: |
PCT/US05/35218 |
371 Date: |
September 4, 2007 |
Current U.S.
Class: |
123/527 ;
123/557; 123/672 |
Current CPC
Class: |
F02M 17/20 20130101;
F02D 41/003 20130101; Y02T 10/12 20130101; F02M 31/18 20130101;
F02M 31/183 20130101; F02D 41/1459 20130101; Y02T 10/126
20130101 |
Class at
Publication: |
123/527 ;
123/557; 123/672 |
International
Class: |
F02B 43/04 20060101
F02B043/04; F02D 35/00 20060101 F02D035/00; F02M 31/18 20060101
F02M031/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 4, 2005 |
US |
11073050 |
Claims
1-4. (canceled)
5. A fuel supply assembly comprising: a vaporization tank to
vaporize an amount of fuel; an air conduit to induct air and
intermix the vaporized amount of fuel with the air prior to entry
into a combustion chamber; a controller adapted to control the
vaporization of the amount of fuel by incrementally increasing the
temperature of the amount of fuel prior to combustion.
6. The fuel supply assembly of claim 5 wherein the controller
further controls a plurality of valves coupled to the air conduit,
the plurality of valves adapted to control the intermixing of the
vaporized amount of fuel with the air.
7. The fuel supply assembly of claim 6, wherein the controller
controls the plurality of valves to maintain a desired air-to-fuel
mixture.
8. The fuel supply assembly of claim 7, wherein the controller
controls the plurality of valves to maintain a desired air-to-fuel
mixture of approximately 14.7 to 1.
9. The fuel supply assembly of claim 5, wherein the controller
incrementally increases the temperature of the amount of fuel in
response to a detection of a condition change.
10. The fuel supply assembly of claim 9, wherein the condition
change is a loss of power.
11. The fuel supply assembly of claim 5, wherein the controller
incrementally increases the temperature of the amount of fuel in
response to an O.sub.2 sensor detecting low hydrocarbon levels.
12. The fuel supply assembly of claim 5, wherein the controller
incrementally increases the temperature of the amount of fuel by
increments of about one degree.
13. The fuel supply assembly of claim 5, wherein the controller
incrementally increases the temperature by increments of about two
degrees or more.
14. A method comprising: inducting an amount of fuel into a
vaporization tank; incrementally increasing the temperature of the
amount of fuel in the vaporization tank to vaporize different
portions of the amount of fuel; intermixing an amount of air with
the different vaporized portions of the amount of fuel; and
controlling the intermixing of the different vaporized portions of
the amount of fuel with the amount of air to maintain a desired
air-to-fuel mixture.
15. The method of claim 14 wherein incrementally increasing the
temperature of the amount of fuel comprises increasing the
temperature of the amount of fuel by increments of approximately
two degrees or more.
16. The method of claim 14 wherein controlling the inducting of the
amount of air into the vaporization tank comprises controlling a
plurality of valves coupled to an air conduit adapted to induct the
amount of air.
17. The method of claim 14, wherein the incrementally increasing
the temperature of the amount of fuel comprises incrementally
increasing the temperature of the amount of fuel in response to a
detection of low power.
18. The method of claim 14, further comprising monitoring
hydrocarbons in combustion exhaust, and incrementally increasing
the temperature of the amount of fuel in the vaporization tank in
response to detecting a determined hydrocarbon level.
19. The method of claim 14, further comprising purging the
vaporization tank.
20. The method of claim 19, further comprising purging the
vaporization tank in response to the temperature of the amount of
fuel reaching a determined temperature.
21. A method comprising: inducting an amount of fuel into a
vaporization tank; intermixing an amount of air with vaporized
portions of the amount of fuel to create a fuel charge of a desired
air-to-fuel ratio; and increasing the temperature of the fuel
charge prior to the fuel charge entering a combustion chamber.
22. The method of claim 21, wherein increasing the temperature of
the fuel charge comprises increasing the temperature of the amount
of fuel inducted into the vaporization tank.
23. The method of claim 21, wherein increasing the temperature of
the fuel charge comprises increasing the temperature of the amount
of air by increasing the temperature of the amount of fuel inducted
into the vaporization tank.
24. The method of claim 21, wherein increasing the temperature of
the fuel charge comprises increasing the temperature of the
vaporized portions of the amount of fuel by increasing the
temperature of the amount of fuel inducted into the vaporization
tank.
Description
RELATED APPLICATION
[0001] This is a continuation-in-part of co-pending U.S. patent
application Ser. No. 10/706,507 entitled "Vapor Fueled Engine"
filed on Nov. 11, 2003, and claims priority to said '507
application.
FIELD OF THE INVENTION
[0002] This invention relates to the use of vaporized fuel to power
an engine and, more particularly, to improvements that enhance fuel
efficiency.
BACKGROUND OF INVENTION
[0003] It is known that under some conditions the use of vaporized
fuel versus liquid fuel for gasoline powered vehicles can reduce
the emission of hydrocarbons conveyed into the atmosphere, while
also increasing fuel efficiency. The problem that has lingered is
how to obtain and retain those benefits over the changing
conditions in which such vehicles are typically driven.
SUMMARY OF THE INVENTION
[0004] As known and as described in the commonly owned U.S. patent
application Ser. No. 10/002,351, now U.S. Pat. No. 6,681,749,
(incorporated herein by reference), fuel efficiency can be improved
by heating a quantity of gasoline to cause vaporization, directing
the vapor into a stream of ambient air, establishing a desired
air-to-fuel mixture and directing the mixture into the intake
manifold of an engine.
[0005] Whereas the system as disclosed in the above application has
resulted in significant improvement, it has not achieved the
consistency of operation desired.
[0006] It is known that there is an optimum fuel-to-air mixture
that needs to be maintained. A fuel-to-air mixture of 1 to 20 is
likely too rich resulting in an unacceptable percentage of
hydrocarbons in the fuel that are not properly combusted and fuel
efficiency is reduced. A 1 to 40 mixture is too lean with today's
catalytic converters (CATs) and produces an emission of nitrogen
oxide that is prohibited by the EPA emission standards. A
fuel-to-air mixture of about 1 to 30 is about optimal for current
gasoline engines used in vehicles and an objective of the invention
is to control the fuel-to-air mixture to maintain the ratio in the
range substantially at, e.g., 1 to 30.
[0007] Consistent with the above objective, the mixture is
monitored and adjusted throughout operation of the engine. This is
accomplished automatically by the use of valves that control the
flow of vapor fuel and/or ambient air that is mixed prior to entry
of the vapor fuel into the engine's intake manifold. The valves are
coupled to a control that is in turn coupled to a vehicle's 02
sensor which senses 02 emissions in a vehicle's exhaust (a standard
feature on most modern vehicles.) It has been learned that the 02
emissions are directly related to hydrocarbon emissions which as
explained is a reflection of the fuel-to-air mixture.
[0008] In the preferred embodiment, an electrical output from the
02 sensor is transmitted to the mentioned control. It is known that
the desired reading for the voltage output of the sensor as
measured by the control is, e.g., 3 volts. At startup, the reading
will typically be at, e.g., 4 volts, indicating a too rich mixture
but desirable for startup and warming of the engine. After a time
delay to accommodate warm up, any reading above or below, e.g., 3,
will activate the control for opening and closing the valve or
valves which control ambient air flow and vaporized fuel flow (more
accurately an enriched mixture of air and fuel). For example, a 3.2
reading will produce an opening of the ambient air valve and/or a
closing of the vaporized fuel flow. A 2.8 reading will produce the
reverse.
[0009] Whereas it would be presumed and has been assumed that an
established fixed setting of fuel-to-air mixture would produce a
stabilized mixture throughout the operation of the engine, such has
been determined to be not the case. There are many variables that
need to be controlled or accommodated. The liquid fuel temperature
is known to have the greatest impact on hydrocarbon emissions and
fuel efficiency, and that temperature will vary by small but very
significant degrees of temperature due to environmental changes,
i.e., temperature, elevation, humidity, and the like. Thus, in the
preferred embodiment, a quantity of fuel to be vaporized is
precisely temperature controlled to substantially eliminate the
effect of such environmental variables.
[0010] Regardless, there still remain significant changes that are
not controlled simply by maintaining the liquid fuel temperature.
These remaining variables are accordingly accommodated by
monitoring the 02 sensors. To the extent that the fuel mixture
strays from the desired reading from the 02 monitor, the mixture is
corrected, i.e., by changing the setting of a valve or valves.
[0011] Whereas the above improvements are considered the primary
features for the preferred embodiment, the following is also
considered to provide additional benefit.
[0012] Again in the preferred embodiment, a quantity of liquid
fuel, e.g., one gallon of fuel, is inserted into a vaporization
tank. The fuel occupies, e.g., the lower half of the tank, and a
heating element and temperature sensor is provided in the
fuel-containing portion of the tank. The temperature is set and
maintained at, e.g., 74 degrees, and that temperature causes
vaporization of the fuel, the vapor rising from the liquid surface
into the upper half of the tank. Within the tank, in the upper
half, there is an ambient air inlet and a vaporized fuel outlet. A
sequence of baffles directs air from the inlet and across the
surface of the liquid fuel to the outlet which is connected to an
outer first conduit. The ambient air temperature is stabilized by
its movement over the liquid and in the process mixes with the
rising fuel vapor. As expelled through the outlet and into the
first conduit, such becomes the vaporized fuel heretofore alluded
to and which is perhaps more correctly identified as an enriched
fuel air mixture. A secondary source of ambient air is conducted
through a second conduit and merges with the vaporized fuel of the
first conduit. Prior to said joining of the air and vaporized fuel,
at each or a selected one of the first and second conduits, control
valves are provided which control the flow volume from the
respective conduits to vary the amount of ambient air and vaporized
fuel that is combined into a third conduit or continuing conduit
(also referred to as a mixing chamber) which in turn conveys the
mixture to the engine's intake manifold.
[0013] A further problem for which a solution had to be derived was
the discovery that the process as described, when vaporizing the
common gasolines that are commercially available, generates a
liquid residual that does not readily vaporize, e.g., at the
temperature setting considered otherwise optimal. Over a period of
time, this liquid residual becomes a greater and greater portion of
the liquid content of the vaporization tank. Thus, a provision is
made for a periodic purging of the liquid residual from the
tank.
[0014] Whereas it was determined that the residual liquid burned
acceptably well in conventional engines, and particularly to the
extent that the systems of the preferred embodiment are adaptable
and applied as retrofits to such conventional engines, a first
solution is the alternate running of the engine, i.e., on vaporized
fuel as described above, and then, as desired, converting back to
conventional liquid fuel operation wherein the residual liquid is
used to fuel the engine. A recycling procedure may be established
to (a) fill the tank with e.g., a gallon of liquid gasoline; (b)
vaporizing 80% of the fuel and then switching to conventional
engine operation to burn off the liquid residual; and (c) refill
the tank and switch back to vaporized fuel. Other solutions are
certainly contemplated. The residual can be simply extracted from
the tank on a periodic basis, stored until refueling is required,
and then disposed of or preferably transferred for use in a
conventional engine use.
[0015] A further enhancement to fuel economy was discovered by
incremental increases in the temperature settings for heating the
fuel in the vaporization tank. For example, it may be found optimal
to heat the fuel to a temperature of e.g. 80 degrees at the outset,
but the chemical makeup of that fuel changes as the more active
component of the fuel vaporizes. The same temperature produces less
vapor and the engine will detectably lose power. At a detected
power loss it may be desirable to raise the temperature e.g. to 82
degrees which will increase vaporization and reinstate the power.
Whereas theoretically the heat can be repeatedly increased to the
point where virtually all of the fuel is vaporized, it is
considered a more desirable practice to stop the incremental
heating at a point where the residual component can still be
effectively used as a liquid fuel. For example, the temperature can
be increased in 1 or 2-degree increments up to 100 degrees (or
where substantially 80% of the fuel is vaporized). At that point
the process is interrupted and the vaporizing tank purged and
refilled with fresh fuel.
[0016] The invention will be more fully appreciated and understood
by reference to the following detailed description and drawings
referred to therein.
DESCRIPTION OF THE FIGURES
[0017] FIG. 1 is a schematic overview of a preferred embodiment of
the invention;
[0018] FIG. 2 is an operational diagram of the system utilized for
the embodiment of FIG. 1;
[0019] FIG. 3 is an exploded view of the vaporization tank of FIG.
1; and
[0020] FIG. 4 is a further exploded view illustrating in particular
the control valves of the system of FIGS. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Reference is made to FIG. 1, which provides a schematic
overview of the components of a system in accordance with the
present invention. A gasoline-powered engine as labeled, includes
an intake port 10 connected to the engine's throttle body. The
engine, when operating, draws air and fuel through port 10. The
engine includes an exhaust pipe 12 that is equipped with an 02
sensor 14. The engine, intake port 10 and 02 detector 14 may be
standard equipment provided for a conventional gasoline-driven
vehicle, and the remainder of the components of the illustrated
embodiment are incorporated into the system to achieve the
objectives of the present invention.
[0022] Item 16 represents an air box through which ambient air is
drawn when operating the engine. Air conducting conduits 18 and 20
from air box 16 provide the desired airflow to the remainder of the
system as will be described.
[0023] Conduit 20 includes a valve 22 that controls the volume of
air directed through conduit 20 and which is conveyed to a vapor
producing tank 26 via the tank's top or cover 24.
[0024] Conduit 18 includes a valve 28 which controls the volume of
ambient air that is directed into a mixing chamber 30.
[0025] Returning to the vapor-producing tank 26, the tank is
provided with flow control apparatus, e.g., baffles, which will be
later explained, but for this overview description it will be
understood that air from conduit 20 (as controlled by valve 22)
enters the tank 26 through the top 24, liquid fuel 28 is drawn from
a gas tank 32 via conduit 34, hot water heating coils immersed in
the liquid fuel via inlets and outlets 36, 38 heat the gas/fuel 28
and generate vapors 40. The vapors are picked up by the airflow
from air conduit 20 and directed out through conduit 42 to the
mixing chamber 30 but controlled by valve 44. The air vapor mixture
of conduit 42 is intermixed in mixing chamber 30 with ambient air
from conduit 18, and the mixture is directed through the intake
port 10 and from there into the combustion tank of the engine.
[0026] Reference is now also directed to FIG. 2 which illustrates
an automatic control process for the air, vapor, and fuel flow
rates referred to in FIG. 1. Each valve 22, 28 and 44 are opened
and closed as desired (between any of the unlimited positions
between fully opened and fully closed) by motors, e.g., stepper
motors 22' 28' and 44'.
[0027] It has been determined that fuel efficiency can be measured
by the hydrocarbons that are emitted from the vehicle exhaust.
Unfortunately, the elimination of hydrocarbons from
gasoline-produced engines currently available cannot be total as
such produces an undesired and unpermitted emission of nitrogen
oxides. Thus, one first determines the level of nitrogen oxide that
is permitted and then the lowest level of hydrocarbons that will
stay within the limits permitted for the restriction on nitrogen
oxide.
[0028] It has further been determined that 02 detectors for
detecting a level of 02 in the vehicle's exhaust and which have
been incorporated into the exhaust system of later model vehicles,
are directly related to the level of hydrocarbons in that same
exhaust. Thus, one can determine what 02 reading of the detector 14
produces the optimum fuel efficiency. For example, a desired
hydrocarbon level may be determined to exist when the 02 monitor
produces a reading of 3 volts.
[0029] Returning to FIG. 1, it has been determined that fuel
efficiency is achieved by controlling the ratio of fuel-to-air
mixture achieved at the mixing chamber 30 from which the mixture
enters the engine intake throttle body. It is known that the
vapor-air-mixture directed into the mixing chamber 30 from conduit
42 is too rich, e.g., 1 part fuel to 10 parts air, and of course
the air only from conduit 18 has zero parts fuel. The desired
mixture may be that which achieves a 30 to 1 ratio, e.g., of 2
cubic feet of air, through valve 28 for each cubic foot of
air/vapor through valve 44.
[0030] Whereas the valves 28 and 44 can be set to achieve the
desired mixture at a given point in time, it has been learned that
many factors affect the ratio achieved in the vapor/fuel mixture
flowing through conduit 42.
[0031] Assuming a specific hydrocarbon emission is desired, a
reading of the 02 detector will verify that this desired mixture
has been achieved, as that reading also indicates the hydrocarbons
in the exhaust. As explained, a fixed setting will not likely
achieve the optimum ratio over any given period of time. Any
temperature change, any elevational change and even differences in
fuel make up will skew the vapor/fuel mixture flowing from the tank
26 to the mixing chamber 30.
[0032] Accordingly, the valves 22, 28 and 44 are operated by
stepper motors 22', 28' and 44' (illustrated in the flow chart of
FIG. 2 and in exploded perspective view in FIG. 4) which stepper
motors are automatically operated by computer C. Computer C
monitors the 02 and thus the hydrocarbon emissions in exhaust 12
and should those readings indicate too high or too low
hydrocarbons, the stepper motors are activated by the computer to
change the relative fluid volumes from conduit 18 and conduit 42.
Should the reading show a too high hydrocarbon level, the vapor/air
flow of conduit 44 needs to be lessened, e.g., the valve 44 closed,
or, e.g., the valve 28 opened, or, e.g., both closing of valve 44
and opening of valve 28.
[0033] The adjustment may take place in stages, i.e., a 1.degree.
closing of valve 44, a re-reading of the 02 detector followed by
repeated partial closing of valve 44 or alternatively the partial
opening of valve 18 or a combination of both. Valve 22 can also be
a factor as restricting air flow into conduit 20 will slow the flow
of air to the tank 26, thus to conduit 42, while also diverting
more airflow through valve 28.
[0034] The structure as described enables the designer to design a
system that will theoretically provide the desired result in
fuel-to-air mixture (e.g., 1 to 30) as deemed desirable, but then
in recognition of the impact of small environmental changes that
produce substantial deviations in efficiency, provide automatic
adjustments that are responsive to real time readouts from an
exhaust monitor, e.g., an 02 detector.
[0035] Reference is now made to FIG. 3, which illustrates the
components of the vaporizing tank 26. The tank 26 consists of a
metal box 48 having dimensions of about 4''.times.8''.times.12''.
Fitted to the bottom of the tank is a hot water coil 50 that
includes an inlet 52 and outlet 54 which, when assembled to the box
48, extends from the box via inlet 52' and outlet 54'.
[0036] Seated onto the box bottom and over the coil 50 is a baffle
grid 56. The plates of the baffle grid 56 include slots 58 which
enable the seating of the grid over the coil 50. Baffle grid 56
includes fastener tabs 60 and assembled to the fastener tabs 60 is
a lower baffle plate 62 having spaced circular opening 64. The
baffle plate 62 is seated below the upper edge of box 48 (defined
by flange 84) and affixed to the flange 84 is an upper baffle plate
66. Extending flanges 68 of baffle plate 66 protrude laterally from
the box and provide the means to secure the box 48 to the body of
the vehicle. Upper flange 68 has rectangular openings 70.
[0037] Secured to the upper baffle plate 66 and in alignment with
an air inlet to be described is a secondary upper baffle plate 72,
reduced in size and secured to the upper plate 66 so as to cover a
substantial portion of the opening 70'. Provided in this secondary
plate is a plurality of small holes, e.g., five holes 74 having a
size of about a quarter inch in diameter. Baffle plate 72 provides
an impediment to airflow from air inlet 78 and diverts the air flow
laterally and downwardly within the tank 26.
[0038] Completing the assembly is the top or cover 24 which has a
complex shape which can be described as a distorted pyramid shape.
The apex of the pyramid shape is positioned at one end whereat an
air inlet 78 is provided A vapor air outlet 80 is provided at the
same end but along the side wall of the pyramid shape. The flange
82 forming the peripheral edge of the top 24 includes bolt holes
which line up with bolt holes in flange portion 76 of baffle plate
66 and with bolt holes in a flange 84 forming the peripheral edge
of box 48. Bolts (not shown) are inserted through the aligned bolt
holes to fasten the components together. A float 86 contained in
the box 48 determines the level of liquid gasoline contained in the
box. The liquid gasoline enters the box through conduit 34 and a
recycling conduit 90 is provided to drain and/or circulate the
gasoline in the vaporizing tank 26 as may be desired.
[0039] In operation liquid gasoline is filled to a level of about
3/4 inch in the bottom of the box 48 which is above the position of
the heater coils 50 and below the top of the baffle grid 56. The
baffle grid 56 and baffle plate 62 primarily prevent sloshing of
the gasoline during driving of the vehicle. As the liquid gasoline
vaporizes (induced by the heating coil 50) air from inlet 78 is
dispersed across the liquid surface via baffle plates 72 and 68
which collects vapors 40 (see FIG. 1) and is then directed through
outlet 80 and to the mixing chamber 30 via conduit 42 as previously
discussed.
[0040] As gasoline is vaporized and drawn from the surface of the
liquid gasoline, the gasoline level diminishes which is detected by
the float 86. As determined desirable by the system, the gasoline
is replenished through inlet 34. After some period of time, the
gasoline starts to become contaminated (does not vaporize) and it
is desirable to purge the tank. This can be done by converting the
engine to gasoline use and drawing the residual gas of the tank 26
through the conventional gas injection system. It can also be
simply drained into a holding tank and utilized for other power
equipment, e.g., a powered law mower.
[0041] As explained in the Summary of the Invention, a further
improvement is the controlled modification to the temperature of
the fuel in the vaporization tank. The temperature at the outset is
established to provide a desired vaporization of a quantity of
fresh fuel, e.g. 74 degrees (but note this initial desired
temperature will likely change with different fuel types and for
example 80.degree. may be just as valid a start temperature). A
temperature sensor previously referred to is utilized to control
the heat generated by a heating source, e.g. the indicated water
heating coils immersed in the liquid fuel.
[0042] The power generated by the engine at the initial fuel
temperature is monitored and when a determined power loss is
detected, the temperature of the fuel in the vaporization tank is
increased, e.g. by 1 or 2 degree increments. The loss of power is
simply a result of the above described vaporization process. The
liquid gasoline produces more vapors initially than it does as time
goes on. The engine requires a quantity of vapor to run correctly
and that quantity of vapor exists when the gasoline is fresh but
not after some time vaporizing. This loss of power is detected by
the 02 sensor that reports the air to fuel ratio. Many things such
as high or low levels of hydrocarbons, carbon dioxide and oxygen
can be derived from the 02 sensor. When there is a loss of power,
the hydrocarbons and carbon dioxide levels go extremely low and the
oxygen level goes extremely high as well as higher air to fuel
ratio. Any or all of these can be utilized as a signal for loss of
power.
[0043] The initial cure to the power loss is to adjust either the
ambient air valve 28 or vapor value 44 or both. As the vaporization
process continues, the ambient air valve will close and the vapor
valve will open in response to the less and less potent liquid
gasoline that is producing the required vapor. Eventually the vapor
valve will be fully opened and the free air valve will be fully
closed. At this point the temperature of the fuel is increased.
Heating the gasoline in 1 or 2 degree increments is enough to
increase the production to adequately provide the needed fuel
vapors to the engine. As the heat is increased, the vapor valve
moves away from its fully opened position until the new temperature
is no longer adequate at which time the vapor valve opens and will
eventually will be fully opened until more heat is added to the
liquid gasoline. The process will repeat itself until a
predetermined temperature is reached at which time the remaining
liquid is drained, e.g., using the stock fuel injection system.
[0044] The formula for signaling the change from vapor to liquid
fuel is as follows: highest allowed heat of liquid gasoline plus
vapor valve fully opened plus input that the engine is no longer
being provided the needed vapor to perform properly equals switch
from vapor system to stock fuel injection system and burn-off
residual liquid.
[0045] The system is designed so that the residue in the tank does
not become so contaminated that it cannot be effectively used as a
liquid fuel supply. For example, it may be determined that a power
loss detected with the fuel in the tank heated to 100 degrees will
trigger the switch-over, i.e., purging of the tank. Other
triggering mechanism may be utilized such as monitoring the fuel
volume and initiating switch-over, e.g. when 80% of the fuel is
depleted.
[0046] Whereas the above is considered a preferred embodiment, the
reader will readily understand that numerous modifications and
variations may be made without departing from the intended scope of
the invention. Accordingly, the invention is not limited to the
structures as described above but fully encompasses the definitions
of the appended claims.
* * * * *