U.S. patent application number 15/884297 was filed with the patent office on 2018-11-08 for carbureted engine having an adjustable fuel to air ratio.
The applicant listed for this patent is INI Power Systems Inc.. Invention is credited to Larry J. Markoski, Timothy C. Simmons.
Application Number | 20180320636 15/884297 |
Document ID | / |
Family ID | 54252374 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180320636 |
Kind Code |
A1 |
Markoski; Larry J. ; et
al. |
November 8, 2018 |
CARBURETED ENGINE HAVING AN ADJUSTABLE FUEL TO AIR RATIO
Abstract
A simple engine, comprises (1) a cylinder, and a spark plug in
the cylinder; (2) a carburetor, fluidly connected to the cylinder;
(3) a primary air intake path, fluidly connecting atmosphere to the
carburetor; (4) a carburetor bypass air intake path, fluidly
connecting air to the cylinder without passing through the
carburetor; and (5) a valve, along the carburetor bypass air intake
path, for controlling the flow of air through the carburetor bypass
air intake path.
Inventors: |
Markoski; Larry J.;
(Raleigh, NC) ; Simmons; Timothy C.; (Durham,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INI Power Systems Inc. |
Morrisville |
NC |
US |
|
|
Family ID: |
54252374 |
Appl. No.: |
15/884297 |
Filed: |
January 30, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14493168 |
Sep 22, 2014 |
9909534 |
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15884297 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02B 63/04 20130101;
F02M 17/38 20130101; F02B 75/16 20130101; F02M 17/34 20130101; F02P
13/00 20130101; F02M 7/12 20130101; F02M 35/1017 20130101; F01P
7/16 20130101; F01P 3/02 20130101; F02B 25/14 20130101 |
International
Class: |
F02M 17/38 20060101
F02M017/38; F02P 13/00 20060101 F02P013/00; F02M 35/10 20060101
F02M035/10; F02M 17/34 20060101 F02M017/34; F02M 7/12 20060101
F02M007/12; F01P 3/02 20060101 F01P003/02; F02B 63/04 20060101
F02B063/04; F02B 75/16 20060101 F02B075/16; F01P 7/16 20060101
F01P007/16 |
Claims
1. A simple engine, comprising: (1) a cylinder, and a spark plug in
the cylinder, (2) a carburetor, fluidly connected to the cylinder,
(3) a primary air intake path, fluidly connecting atmosphere to the
carburetor, (4) a carburetor bypass air intake path, fluidly
connecting air to the cylinder without passing through the
carburetor, and (5) a valve, along the carburetor bypass air intake
path, for controlling the flow of air through the carburetor bypass
air intake path.
2. The simple engine of claim 1, wherein the engine further
comprises an air filter, and the carburetor bypass air intake path
draws air through the air filter.
3. The simple engine of claim 1, wherein the engine further
comprises an air filter, and both the primary air intake path, and
the carburetor bypass air intake path, draw air through the air
filter.
4. The simple engine of claim 1, wherein the engine further
comprising a gasket spacer, between the carburetor and the
cylinder, and the carburetor bypass air intake path feeds air into
the gasket spacer.
5. The simple engine of claim 4, wherein the gasket spacer
comprises a metal.
6. The simple engine of claim 4, wherein the gasket spacer
comprises brass.
7. A generator, comprising the simple engine of claim 1.
8. A flexible fuel generator, comprising the simple engine of claim
3.
9. The flexible fuel generator of claim 8, further comprising: (6)
a primary fuel tank, fluidly connected to the carburetor, (7) a
coolant path, which provide a flow path for coolant to cool the
cylinder, (8) a thermal controller, along the coolant path, and (9)
a start module, comprising a starting fuel tank holder and a
starting fuel line, wherein the starting fuel line is fluidly
connected to the primary air intake path or the carburetor bypass
air intake path.
10. The generator of claim 7, wherein the generator is a 1 kW, 2kW
or 5 kW generator.
11. The flexible fuel generator of claim 9, wherein the generator
is air-cooled.
12. The simple engine of claim 1, wherein the simple engine is part
of a lawn mower; a leaf blower; a motor cycle without a fuel
injector; a moped; an ATV; or a dirt bike.
13. The flexible fuel generator of claim 9, wherein the cylinder
comprises aluminum.
14. The flexible fuel generator of claim 9, further comprising a
generator housing enclosing the cylinder, wherein the start module
is attached to the generator housing.
15. The flexible fuel generator of claim 9, further comprising a
starting fuel tank, fluidly connected to the starting fuel
line.
16. The flexible fuel generator of claim 15, further comprising a
starting fuel dispenser, fluidly connecting the starting fuel tank
to the starting fuel line.
17-24. (canceled)
25. The flexible fuel generator of claim 9, further comprising a
generator housing enclosing the cylinder, wherein the start module
is attached to the generator housing, and wherein the generator is
air-cooled, the cylinder comprises aluminum, the generator does not
include a battery, the start module further comprises a starting
fuel enclosure, the starting fuel line is connected to an air
intake path between the air filter and the cylinder, the coolant
path has an entrance for air to enter the generator and an exit for
air to exit the generator, the thermal controller is a thermal
door, and the thermal door is at the exit of the coolant path.
26. A method of running a simple engine, comprising: supplying air
and fuel to a carburetor, to produce an air fuel mixture, supplying
the air-fuel mixture to a cylinder, supplying additional air to the
cylinder, wherein the additional air does not go through the
carburetor, and igniting the fuel in the cylinder to drive the
engine.
27-31. (canceled)
32. A simple engine, comprising: (i) a cylinder, and a spark plug
in the cylinder, (ii) a carburetor, fluidly connected to the
cylinder, (iii) a primary air intake path, fluidly connecting
atmosphere to the carburetor, and (iv) a carburetor bypass,
comprising (a) an inlet tube, fluidly connecting to the air, (b) a
valve, fluidly connected to the inlet tube, and (c) an outlet tube,
fluidly connected to the cylinder, wherein the carburetor bypass
provides air to the cylinder bypassing the carburetor.
33-37. (canceled)
38. A method of making a modified engine from a simple engine, the
simple engine having a cylinder, a spark plug in the cylinder, a
carburetor fluidly connected to the cylinder, and a primary air
intake path fluidly connecting air to the carburetor, the method
comprising: adding a carburetor bypass to the simple engine,
wherein the carburetor bypass comprises: (a) an inlet tube, fluidly
connecting to the air, (b) a valve, fluidly connected to the inlet
tube, and (c) an outlet tube, fluidly connected to the cylinder,
and the carburetor bypass provides air to the cylinder bypassing
the carburetor.
39-46. (canceled)
Description
BACKGROUND
[0001] Generators for producing electricity are well known and have
been commercially available for many years. These devices typically
include an internal combustion engine. They are adapted to provide
alternating current (AC) electricity, through a standard two-prong
or three-prong plug receiver, at 120 or 240 volts, and at 50 to 60
Hz; also common is an additional 12 volt DC power port for charging
lead acid batteries. Devices which use either gasoline-only or
heavy fuels only, such as JP-8, diesel fuel, jet fuel or kerosene,
are available.
[0002] Gasoline has a low-flashpoint (less than -20.degree. C.) and
high autoignition temperature (greater than 200.degree. C.). In
operation gasoline requires the proper air to fuel ratio and a
spark to induce and maintain ignition. A throttle and/or fuel
injector is used to meter the fuel/air mixture which is sucked into
the cylinders of the engine during operation. The low flashpoint
and volatility of gasoline allows starting of the spark ignition
engine at temperatures below freezing, allowing for operation over
a broad range of temperatures typically between -20.degree. C. to
55.degree. C. In order to obtain acceptable efficiency, a
compression ratio of 8:1 to 12:1 is desirable for a gasoline-only
engine, which is low enough to allow for manual pull-starting of
the engine and the construction of simple lightweight portable
engine devices made of aluminum.
[0003] Portable gasoline generators have a simple design in order
to keep them light, low cost and durable. Such devices include an
engine having a carburetor for mixing air and fuel, and do not
include a fuel injector. A carburetor jet controls the maximum
amount of fuel present in the air-fuel mixture exiting the
carburetor, and a choke is used to reduce the amount of air in the
air-fuel mixture, for starting the engine. The size of the jet is
selected to provide good performance at maximum power of the engine
under typical conditions, such as 25.degree. C. ambient temperature
and sea level altitude. As the environment of the engine deviates
from those typical conditions, the performance of the engine
becomes changes. If the environment deviates too much, it is not
possible to properly operate the engine unless a different jet is
used to increase the air-fuel ratio. For example, at altitudes
above 5000 feet, most small portable gasoline generators will not
operate unless a different jet is installed into the device. More
sophisticated engines, such as those found in modern automobiles,
use oxygen sensors and a fuel injector to increase the air in the
air-fuel mixture so that the engine will operate efficiently at
high altitudes and at higher than normal ambient temperatures.
Therefore, in order to use a small portable generator that can be
used in a variety of conditions, such as varying altitudes, it is
necessary to also have available appropriate tools for opening the
generator and removing the existing jet, a selection of jets
varying in size, appropriate charts for selecting the correct jet
for each altitude, as well as maps or an altimeter for determine
the altitude where the generator will be operating. Furthermore,
changing out the jet in a small portable gasoline generator is a
somewhat complex operation involving opening the engine and
handling parts which have been exposed to gasoline, which may not
be desirable for typical consumers, especially in the locations
where the generator will be used.
SUMMARY
[0004] In a first aspect, the present invention is a simple engine,
comprises (1) a cylinder, and a spark plug in the cylinder; (2) a
carburetor, fluidly connected to the cylinder; (3) a primary air
intake path, fluidly connecting atmosphere to the carburetor; (4) a
carburetor bypass air intake path, fluidly connecting air to the
cylinder without passing through the carburetor, and (5) a valve,
along the carburetor bypass air intake path, for controlling the
flow of air through the carburetor bypass air intake path.
[0005] In a second aspect, the present invention is a generator,
comprising the simple engine.
[0006] In a third aspect, the present invention is a flexible fuel
generator, comprising the simple engine.
[0007] In a fourth aspect, the present invention is a method of
running a simple engine, comprising supplying air and fuel to a
carburetor, to produce an air fuel mixture; supplying the air-fuel
mixture to a cylinder; supplying additional air to the cylinder;
and igniting the fuel in the cylinder to drive the engine. The
additional air does not go through the carburetor.
[0008] In a fifth aspect, the present invention is a method of
generating electricity, comprising running a simple engine by the
method. The simple engine is part of a generator.
[0009] In a sixth aspect, the present invention is a simple engine,
comprising (i) a cylinder, and a spark plug in the cylinder; (ii) a
carburetor, fluidly connected to the cylinder; (iii) a primary air
intake path, fluidly connecting atmosphere to the carburetor; and
(iv) a carburetor bypass. The carburetor bypass comprises (a) an
inlet tube, fluidly connecting to the air; (b) a valve, fluidly
connected to the inlet tube, and (c) an outlet tube, fluidly
connected to the cylinder. The carburetor bypass provides air to
the cylinder bypassing the carburetor.
[0010] In a seventh aspect, the present invention is a method of
making a modified engine from a simple engine. The simple engine
has a cylinder, a spark plug in the cylinder, a carburetor fluidly
connected to the cylinder, and a primary air intake path fluidly
connecting air to the carburetor. The method comprises adding a
carburetor bypass to the simple engine. The carburetor bypass
comprises (a) an inlet tube, fluidly connecting to the air; (b) a
valve, fluidly connected to the inlet tube; and (c) an outlet tube,
fluidly connected to the cylinder. The carburetor bypass provides
air to the cylinder bypassing the carburetor.
DEFINITIONS
[0011] Heavy fuels include diesel fuel, diesel 1, diesel 2,
kerosene, JP-8, JP-5, F-76, DF2 aviation fuel and bio-diesel. Heavy
fuels or gasoline are occasional mixed with a substantial amount of
lubricant, such as oil, to form a fuel-lubricant mixture for use in
two-stroke engine which do not contain a lubricant. Preferably,
Heavy fuels or gasoline is not present as such fuel-lubricant
mixtures.
[0012] Diesel fuel includes diesel 1, diesel 2, JP-8, JP-5, F-76,
DF2 aviation fuel and bio-diesel. Diesel fuel does not include
kerosene.
[0013] Gaseous low-flashpoint fuels include hydrogen, syn gas,
propane and butane.
[0014] Low-boiling point low-flashpoint fuels include diethyl ether
and gasoline. These fuels have a boiling point of 15-50.degree. C.,
and a flashpoint below 0.degree. C.
[0015] Fuels include heavy fuels with high flash point and low
autoignition temperatures, gaseous low-flashpoint fuels,
low-boiling point low-flashpoint fuels and other high flash point
and high autoignition fuels such as methanol, ethanol and
isopropanol. Fuels may contain additives, for example to improve
combustion or reduce emissions.
[0016] A "portable gasoline generator" is a generator that has an
internal combustion engine and includes a pull start and a
carburetor, and uses a spark to ignite fuel in the engine, and
preferably does not include a battery for starting the engine. The
compression ratio used in the engine is greater than 8.0:1, and
more preferably 8.1:1 to 12.0:1. Preferably, the engine is
air-cooled, has an aluminum cylinder or cylinders, and uses fixed
spark plug ignition timing. Preferably, the engine is a 4 cycle, 50
cc engine. Examples of a portable gasoline generator include the
YAMAHA Inverter EF1000iS, EF2000iS, and EF2000iSH, as well as the
HONDA EU1000i, EU2000i and EB2000i.
[0017] The term "isothermal" or "isothermally" in the context of
the operation of an engine means that the temperature of the
cylinder(s) is maintained substantially uniform within a desired
temperature range, irrespective of engine RPM or ambient external
temperature.
[0018] A "step-down gas regulator" is a gas regulator that delivers
gas at a pressure of 0.5 to 1 psi, only supplies the gas under
suction. Examples of such regulators are sold under the brand name
"GARRETSON".
[0019] The term "engine" means the internal combustion engine,
which includes at least a cylinder, a piston which moves inside the
cylinder, a spark plug, a fuel-air inlet to the cylinder, an
exhaust outlet from the cylinder, and a drive shaft which moves
with the piston. The term "simple engine" means an engine which
includes a carburetor, a fixed jet, and which does not include a
fuel injector.
[0020] The term "running fuel" means a fuel used to run an engine,
while the term "starting fuel" means a fuel used to start an
engine.
[0021] The term "air intake path" includes both a primary air
intake path and a carburetor bypass air intake path. An air intake
path fluidly connects the atmosphere outside the generator to the
engine, to supply air for combustion of the fuel. The "primary air
intake path" is an air intake path that passes through the
carburetor before entering the cylinder. The "carburetor bypass air
intake path" is an air intake path that provides air to the
cylinder without passing through the carburetor. The primary air
intake path and the carburetor bypass air intake path my share
portions of each path, for example both air intake paths may share
a common intake which passes through the air filter before
splitting off into separate paths.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIGS. 1 and 2 illustrate a flexible fuel generator having a
simple engine including carburetor bypass air intake path.
[0023] FIG. 3 illustrates a start module of a flexible fuel
generator.
[0024] FIG. 4 illustrates starting fuel enclosure of a flexible
fuel generator.
[0025] FIGS. 5 and 6 illustrate the interior of a start module,
with and without a starting fuel tank, respectively, of a flexible
fuel generator.
[0026] FIGS. 7 and 8 illustrate two configuration of the rear of a
flexible fuel generator, providing details of the thermal
controller of a flexible fuel generator.
[0027] FIG. 9 is an exploded view of a flexible fuel generator
having a simple engine including carburetor bypass air intake
path.
[0028] FIG. 10 illustrates a portion of the exploded view of the
flexible fuel generator shown in FIG. 9.
[0029] FIG. 11 illustrates a carburetor bypass.
[0030] FIG. 12 is a graph of the fuel consumption of a 2 kW
flexible fuel generator running on JP-8 fuel, in the normal and
econ modes, without a carburetor bypass air intake path
("unoptimized") or with a carburetor bypass air intake path with
the valve open to maximize efficiency ("optimized").
[0031] FIG. 13 is a graph of CO emissions for a 1 kW flexible fuel
generator running on JP-8 fuel with a fixed jet without a
carburetor bypass air intake path (squares), or with a carburetor
bypass air intake path (triangles), with the valve opened to
maximize efficiency. The dotted line represents the U.S. EPA limit
for a 50 cc engine.
[0032] FIG. 14 is a graph of combustion efficiency for a 1 kW
flexible fuel generator running on JP-8 fuel with a fixed jet
without a carburetor bypass air intake path (squares), or with a
carburetor bypass air intake path (triangles), with the valve
opened to maximize efficiency.
DETAILED DESCRIPTION
[0033] A small portable generator which could be operated on both
gasoline and heavy fuels, such as JP-8, was recently developed
(hereinafter referred to as a "flexible fuel generator"): see
International Application Publication No. WO 2013/103542. This
generator includes a simple engine, and is similar to a small
portable gasoline generator, but has been designed to operate at a
temperature range of 120-180.degree. C. The device also includes a
start module which delivers a small amount of a low-boiling point
low-flashpoint fuel to the carburetor via the air intake, for
starting the engine. This generator is intended for use in remote
field locations, where gasoline may not be readily available.
However, because this generator uses a carburetor having a jet, it
cannot operate properly at high altitudes without changing the jet,
as is the case with other generators having a simple engine.
[0034] The present invention is based on the discovery that
inclusion of a carburetor bypass air intake path, which fluidly
connects atmosphere to the cylinder and bypasses the carburetor,
allows for an increase in the air-fuel ratio which enters the
cylinder. This increased air-fuel ratio may be used to compensate
for the reduced oxygen concentration in the atmosphere at high
altitudes and/or at high ambient temperatures. With a valve along
the carburetor bypass air intake path, either hand operated by the
user, or automated through coupling to an oxygen sensor, an
increased air-fuel ratio may be provided to the cylinder to
compensate for any altitude and/or temperature encountered, without
the need for the equipment and labor necessary to switch out the
carburetor jet. This carburetor bypass air intake path may be
included on any simple engine by adding a carburetor bypass to the
simple engine. Example of devices having simple engines include
generators, such as small portable generators; lawn mowers; leaf
blowers; motor cycles without fuel injectors; mopeds; ATVs; and
dirt bikes.
[0035] Surprisingly, even though the carburetor bypass air intake
path supplies air at a point after the carburetor has already
prepared the air-fuel mixture, the engine operates smoothly. Even
more surprising, this is true when the engine is part of a flexible
fuel generator and the fuel is a heavy fuel, such as diesel fuel
which is not as volatile as gasoline.
[0036] A surprising and unexpected benefit is that adjustment of
the valve along the carburetor bypass air intake path may be used
to dramatically improve the efficiency of a generator having a
simple engine, even under condition (ambient temperature and
altitude) when the generator will operate without the inclusion of
the carburetor bypass. The fuel efficiency is improved about 30%,
and emissions from the generator are reduced by about 30%,
depending on the fuel used in the device. This level of improvement
would be expected in any device containing a simple engine when a
carburetor bypass air intake path is added. Furthermore, the
improvement also extends to a reduction in carbon deposits in the
engine, reducing maintenance such as oil changes and replacement of
spark plugs. Fewer soot particles also reduces the frequency of
changing the spark arrestor.
[0037] FIG. 11 illustrates a carburetor bypass 100 for providing a
carburetor bypass air intake path in a simple engine. The
carburetor bypass includes an inlet tube 112, a valve 108 having a
handle (110 in the open position), and an outlet tube 114. As
illustrated, the outlet tube supplies air through a gasket spacer
102. The outlet tube may include multiple parts; as illustrated it
includes a first tube 106, and a second tube 104. Similarly, the
inlet tube may also include a first tube and a second tube. When
installed into a gasoline generator, the spacer is located between
the carburetor and the cylinder. The inlet tube and the outlet
tube, and the parts thereof, may be made from metal or plastic, but
preferably they are made of materials which will withstand the
temperatures encountered in those parts of the engine. For example,
the first tube may be brass, the second tube may be rubber, and the
inlet tube may be rubber. Although the gasket spacer may be a
plastic material, such as a phenolic resin, preferably the spacer
is metal, such as brass. Preferably, in the case of a flexible fuel
generator, the gasket spacer may be brass having a thickness of 3/8
inch, the valve may be a 1/4 inch ball valve, and the tube entering
the gasket spacer may be brass having a 5/16 inch O.D., cut at a
30.degree. angle towards the cylinder.
[0038] Inclusion of the carburetor bypass creates the carburetor
bypass air intake path, defined by the carburetor bypass. Such a
carburetor bypass may be used to add a carburetor bypass air intake
path to any simple engine, including those of a generators, such as
small portable generators (gasoline or flexible fuel); lawn mowers;
leaf blowers; motor cycles without fuel injectors; mopeds; ATVs;
and dirt bikes.
[0039] In use, a user may start the engine with the choke closed,
then open the choke, and then adjust the valve of the carburetor
bypass, starting in the closed position. While listening to the
engine, the valve is slowly opened until the engine starts to
sputter (for example, the movement of the piston in the cylinder
becomes irregular). This indicates that the fuel is too lean (that
is, the air-fuel ratio is too great). Then the valve is slowly
closed until the engine runs smoothly and the sputtering stops,
indicating that the air-fuel ratio has been selected for maximum
efficiency. Alternatively, the movement of the valve may be
automated by coupling to an oxygen sensor, using the oxygen sensor
to determine when the desired air-fuel ratio has been selected for
maximum efficiency, in the same fashion as used with a fuel
injector.
[0040] The inlet tube may draw air directly from outside the
generator, or may draw air from an air intake path shared with the
primary air intake path. Preferably, the inlet tube draws air which
is filtered, for example from behind the air filter which also
filters air for the primary air intake path. If the inlet tube
draws air directly from outside the generator, then some filter,
constriction, or baffle may be necessary to prevent too much air
from being drawn into the cylinder through the carburetor
bypass.
[0041] A generator including an engine of the present application
may be prepared by modifying a portable gasoline generator, such as
YAMAHA Inverter EF1000iS, EF2000iS, and EF2000iSH, as well as the
HONDA EU1000i, EU2000i and EB2000i, or a flexible fuel generator.
In this case a carburetor bypass is used to create an carburetor
bypass air intake path which draws air from behind the air filter,
through the valve, and into the gasket spacer which separates the
carburetor from the cylinder, by the installation of the carburetor
bypass.
[0042] The generator may optionally include a start module. The
start module includes a starting fuel tank holder and starting fuel
line, for fluidly connecting a starting fuel tank to the air intake
path (either the primary air intake path or the carburetor bypass
air intake path, or common portions of the two air intake paths).
Preferably, the start module includes: a starting fuel tank
containing low-boiling point low-flashpoint fuel, preferably
pressurized, such as a spray can of pressurized diethyl ether
commonly available as starting fluid; a starting fuel dispenser,
for dispensing the low-boiling point low-flashpoint fuel, such as a
spray cap or small mechanical liquid pump; a starting fuel
enclosure, having a starting fuel button access for accessing the
starting fuel dispenser, a starting fuel button cover to prevent
accidental dispensing of the low-boiling point low-flashpoint fuel,
enclosure bolt holes for attaching the starting fuel enclosure over
the starting fuel tank. When present, the enclosure may be attached
to the maintenance panel by bolts. Preferably, the starting fuel
tank holder is attached to the generator housing, such as onto the
maintenance panel. The starting fuel tank holder may be clips (as
illustrated in FIG. 6), an adhesive strip or a strap.
[0043] Preferably, the generator includes an air filter along the
air intake path (either the primary air intake path and/or the
carburetor bypass air intake path, or common portions of the two
air intake paths). When a starting fuel module is present, a
starting fuel line is also present, which may be a simple plastic
tube resistant to damage or chemical reaction from the low-boiling
point low-flashpoint fuel, and preferably delivers the low-boiling
point low-flashpoint fuel as a mist to the air exit side (back) of
an air filter, or to some other point between an air filter and the
cylinder.
[0044] The low-boiling point low-flashpoint fuel is preferably
diethyl ether, such as starting fluid. Preferably, the low-boiling
point low-flashpoint fuel is present in a starting fuel tank, more
preferably as a pressurized fluid. Diethyl ether, particularly in
the form of starting fluid is especially preferred (for example,
VALVOLINE.RTM. Extra Strength Starting Fluid with cylinder
lubricant), because it is conveniently supplied in pressurized cans
of a convenient size; a simple press of the can top for a few
seconds will dispense the desired amount of starting fluid mist.
Gasoline may also be used, but it is less preferred because the
composition and flash point are variable.
[0045] An amount of 0.1 to 10.0 grams, more preferably 0.3 to 3.0
grams, including 1.0, 1.5, 2.0 and 2.5 grams, of the low-boiling
point low-flashpoint fuel is sufficient to start the engine and
sustain combustion of a heavy fuel. Because the low-boiling point
low-flashpoint fuel is provided along an air intake path it will
enter the engine as a vapor. The engine will start and run on a
combination of any liquid fuel from the primary fuel tank and fuel
vapor from an air intake path. As the low-boiling point
low-flashpoint fuel evaporates, it will allow the generator to
rapidly transition automatically to solely the liquid fuel from the
primary fuel tank.
[0046] Any heavy fuel, gasoline, or alcohol and mixtures may be
used as the liquid fuel from the primary fuel tank. In a variation,
the fuel is diesel fuel. Preferably, the heavy fuel is JP-8. It may
be desirable to adjust the size of the jet in the generator to
compensate for the viscosity of the liquid fuel and the anticipated
temperature of the liquid fuel in the primary fuel tank. It may be
desirable to retard the spark plug ignition timing, as compared to
a gasoline engine, because of the faster flame speed of heavy fuel.
The primary fuel tank is fluidly connected to the engine, and
delivers liquid fuel to the carburetor.
[0047] An optional thermal controller adjusts the flow of the
coolant through the generator. Preferably, the coolant is air. For
example, an air fan may pull air through the generator and over the
outside of the cylinder, to cool the cylinder, and then out a
cooling air outlet. In this configuration, the thermal controller
may be a movable sheet of metal or plastic (a thermal door) which
can interrupt the amount of the flow of air, at any point along the
cooling air path. The thermal controller may be moved to increase
or decrease the size of the cooling air outlet. In an alternative
configuration, baffles may be use to increase or decrease the size
of the cooling air outlet or inlet, or along the cooling air path.
In another alternative configuration, the thermal controller may be
a fan or pump coupled to a temperature sensor or thermostat, which
increases or decreases the coolant flow to maintain the temperature
within the desired temperature range.
[0048] Optionally, a thermal controller, such as a thermal door, is
used to maintain the temperature of the cylinder at 120-180.degree.
C., preferably 130-175.degree. C., more preferably 150-170.degree.
C., for example 155-165.degree. C. If the temperature is too low,
or too high, the thermal controller can be used to increase or
decrease the flow of coolant. The temperature of the generator is
preferably the temperature of the cylinder, which may be
conveniently measured at the spark plug using a thermocouple
temperature sensor (for example, a spark plug temperature sensor
available from TRAIL TECH).
[0049] Optionally, the generator may have full cylinder cooling. In
a generator with full cylinder cooling, the isothermal operation of
the engine may be maintained. Preferably, the cylinder comprises
aluminum (that is, the engine block comprises aluminum), which
keeps the generator low in weight, and because of the high thermal
conductivity of aluminum, maintains isothermal operation of the
engine. Preferably, full cylinder cooling comprises cooling the
cylinder at the fuel entrance and/or at the exhaust exit. Full
cylinder cooling may be achieved in larger generators (and larger
simple engines) by using a heat conductive gasket spacer, such as a
3/8 inch brass gasket spacer. Such a gasket spacer is particularly
useful to provide full cylinder cooling in a YAMAHA Inverter
EF2000iSH, as well as the HONDA EU2000i and EB2000i, and similar 5
kW devices.
[0050] Determining if an engine is operating in the isothermal
range of 120-180.degree. C. and has full cylinder cooling, may be
carried out as follows. The temperature of the engine is measured
at the spark plug where it is screwed into the engine block, for
example by a thermocouple attached to a washer. The engine is then
operated on JP-8 fuel. If the engine does not knock over a period
of at least 5 minutes, and the temperature of the engine is
maintained at 120-180.degree. C. during that period, then during
that time period the engine is operating isothermally at
120-180.degree. C. Furthermore, such operation over the 5 minute
period confirms that the engine has full cylinder cooling. In the
case of an engine with multiple cylinders, if the temperature at
each spark plug is maintained at 120-180.degree. C. during the 5
minute period, and knocking does not occur, then during that time
period the engine is operating isothermally at 120-180.degree. C.;
furthermore, such operation over the 5 minute period confirms that
the engine has full cylinder cooling. An example of full cylinder
cooling is the YAMAHA Inverter EF1000iS, which allows air to cool
the cylinder at the fuel entrance and/or at the exhaust exit.
[0051] Preferably, the cylinder has a compression ratio greater
than 8.0:1, for example 8.1:1 to 12:1 or 10:1, including 8.2:1,
8.3:1, 8.4:1, 8.5:1, 8.6:1, 8.7:1, 8.8:1, 8.9:1, 9.0:1 and 9.5:1.
Preferably, the engine is air-cooled, has an aluminum block and
uses fixed timing. Preferably, the engine is a 4 cycle, 50 cc
engine.
[0052] A flexible fuel generator may be prepared by modifying a
portable gasoline generator as described in International
Application Publication No. WO 2013/103542, such as a YAMAHA
Inverter EF1000iS, which is air-cooled, has an aluminum block, uses
fixed timing, and is a 4 cycle, 50 cc engine, having a compression
ratio of 8.2:1. The figures illustrate such a flexible fuel
generator which includes a carburetor bypass air intake path. As
illustrated, a start module is added, which deliver the low-boiling
point low-flashpoint fuel, such as diethyl ether, to the back of
the air filter. A thermal controller is added to the rear of the
generator. A temperature display is added, which displays the
temperature at the spark plug. The fixed spark plug ignition timing
is retarded, by moving the spark ignition coil clockwise from its
original position. A carburetor bypass is added, to provide a
carburetor bypass air intake path. When a starting fuel tank with
starting fuel dispenser is also present, and a heavy fuel such as
JP-8 fuel is present in the primary fuel tank, the generator may be
started by first depressing the dispenser for 1 to 3 second. The
pull start is then used to start the generator, with the thermal
door blocking most of the cooling air outlet. Once the temperature
at the temperature display reaches 120-180.degree. C., the thermal
door may be adjust to maintain that temperature. The design of the
generator does not require modification for isothermal operation,
as the generator has full cylinder cooling. A single can of
VALVOLINE.RTM. Extra Strength Starting Fluid with cylinder
lubricant contains sufficient diethyl ether to start the generator
about 100 times. It may be desirable to use higher quality oil that
resists thermal breakdown, such as AMSOIL.RTM. SAE 10W-40 synthetic
motor oil as the lubricant, or change the lubricant more often, due
to the high temperature operation of the engine. In addition it may
be desirable to perform an engine flush treatment to remove carbon
deposits from the heavy fuels.
[0053] In the case of such a modified portable gasoline generator,
which has also been modified to receive a gaseous low-flashpoint
fuel directly into the carburetor using a step-down regulator, it
is possible to start the generator using only the gaseous
low-flashpoint fuel. Once the temperature of 120-180.degree. C. is
reached, it is possible to switch the fuel supply to a heavy fuel,
such as diesel fuel, from the primary fuel tank, which is using the
gaseous low-flashpoint fuel as the starting fuel and using the
heavy fuel as the running fuel. However, a much larger amount of
gaseous low-flashpoint fuel is needed as compared to low-boiling
point low-flashpoint fuel to sustain combustion, and the
switch-over to the primary fuel tank must be carried out by the
user.
[0054] Examples of flexible fuel generators including a simple
engine having a carburetor bypass air intake path of the present
application are illustrated in the figures.
[0055] FIGS. 1 and 2 illustrate a flexible fuel generator, 10
having a carburetor bypass.
[0056] The generator includes a generator housing, 14, which
encloses the generator engine (not shown). Exhaust from the
generator engine exits through an exhaust outlet (not shown) and
then through an exhaust hose, 12, attached to the exhaust outlet.
The generator housing includes a maintenance panel, 16, and a
fueling port, 22. Attached to the maintenance door is a start
module, 18. A temperature display, 20, on the generator housing
displays the internal temperature of the generator engine. An
auxiliary display, 24, displays other information, such as the
length of time the generator has been operating. A pull start, 26,
for manually starting the engine, passes through the generator
housing. A control panel, 28, is present on the generator housing,
and includes electrical plug receivers, start and stop buttons, and
other controls for controlling the operation of the generator. Also
illustrated is the handle (110 in the open position and 116 in the
closed position) of a valve (108, not illustrated) located outside
the housing. An opening with an air filter 118 provides air
directly to an inlet tube (112, not illustrated).
[0057] FIG. 3 illustrates a start module, 18. The start module is
attached to the maintenance panel, 16. The start module includes a
starting fuel enclosure, 30, which has a starting fuel button
cover, 32, and a starting fuel button access, 34. Also illustrated
are enclosure bolts, 36 and 36, which are used to attach the
starting fuel enclosure to the maintenance panel. FIG. 4
illustrates starting fuel enclosure, 30. The starting fuel
enclosure, 30, has a starting fuel button cover, 32, and a starting
fuel button access, 34. Also illustrated are enclosure bolt holes,
38 and 38, for the enclosure bolts.
[0058] FIGS. 5 and 6 illustrate a start module with the starting
fuel enclosure removed, with and without a starting fuel tank,
respectively. Shown is the maintenance panel, 16. Attached to the
panel are starting fuel tank holders, 40 and 40, for holding a
starting fuel tank, 48. A starting fuel dispenser, 42, may be
attached to the starting fuel tank, to dispense starting fuel. A
starting fuel line, 44, attached to the starting fuel dispenser and
passing through the maintenance panel, transports starting fuel to
the air intake path of the generator. Also shown are enclosure bolt
tabs, 46 and 46, attached to the maintenance panel, for receiving
the enclosure bolts for attaching the starting fuel enclosure to
the maintenance panel of the generator housing.
[0059] FIGS. 7 and 8 illustrate two configuration of the rear of a
flexible fuel generator, providing details of the thermal door.
Shown in these figures are the generator housing, 14, the exhaust
port, 58, to which is attached the exhaust hose, 12. The thermal
door, 50, is slideably attached to the rear of the generator
housing by clasps, 56 and 56, over the cooling air outlet, 54. In
FIG. 7, the thermal door almost completely blocks the cooling air
outlet, while in FIG. 8, the thermal door blocks only a small
portion of the cooling air outlet.
[0060] FIG. 9 is an exploded view of a flexible fuel generator 10,
having a carburetor bypass. Here, the generator housing, 14 has
been split apart to show otherwise hidden elements. Unlike the
flexible fuel generator illustrated in FIG. 1, the carburetor
bypass air intake path draws air from behind the air filter, 62.
The air filter housing includes a front panel, 60 and a rear panel,
64, and the air filter, 62, is between these two panels; these
elements are part of the air intake path (both the carburetor
bypass air intake path and the primary air intake path). Air enters
the generator and is pulled through a lower portion of the rear
panel to a lower portion of the front panel, and then up along the
front panel and through the air filter, and finally out the back of
the upper portion of the rear panel for the primary air intake
path, or into the inlet tube, 112, of the carburetor bypass. As
illustrated in this figure, the carburetor bypass is separated into
the constituent parts for clarity of the relationship of the
constituent parts with other parts of the engine. The carburetor
bypass air intake path includes the inlet tube, 112, and follows
into the valve, 108 (with only the handle (110 in the open
position, and 116 in the closed position) of the valve being shown
in this figure), and then into the first tube, 106, and a second
tube, 104, and finally into the gasket spacer, 102. Also shown in
the figure is starting fuel line, 44, which has an exit end
delivering starting fuel to the back of the air filter (that is,
the side of the air filter facing the rear panel). Although not
illustrated in FIG. 9, the entrance end of the starting fuel line
is attached to starting fuel dispenser, forming a fluid connection
between the starting fuel tank and the air intake path. By
activation of the starting fuel dispenser, for example by pressing
the top of the starting fuel dispenser, starting fuel is dispensed
onto the back of the air filter. Coolant (in this device, air)
flows over the cylinder, 68, including portion of the cylinder at
the fuel entrance, 63, and at the exhaust exit, 65. Also
illustrated in FIG. 9 are the spark plug, 66, the temperature
sensor, 67 (which measure the temperature at the spark plug and is
connected to the temperature display), the carburetor, 69, and the
primary fuel tank, 74.
[0061] FIG. 10 illustrates details of a portion of the exploded
view of the flexible fuel generator shown in FIG. 9. Shown are the
cylinder, 68, the air fan, 72, and the spark ignition coil, 70. The
position of the spark ignition coil controls the timing of the
spark plug, because it is coupled to movement of the drive shaft by
magnets on the air fan (which is connected to the drive shaft); as
the air fan rotates, the magnets actuate the spark ignition coil.
Since the spark ignition coil is electrically connected to the
spark plug, when the spark ignition coil is actuated, a spark is
produced by the spark plug in the cylinder. Furthermore, the air
fan pulls air through the generator and over the outside of the
cylinder, to cool the cylinder, and then out the cooling air
outlet. As is more clearly illustrated in FIG. 9, the outside of
the cylinder includes cooling fins along the full length of the
exterior, so that the cylinder is cooled at both the top and the
bottom and therefore has full cylinder cooling.
EXAMPLES
Example 1: Generator Having a Simple Engine Modified to a Flexible
Fuel Generator Including a Carburetor Bypass Air Intake Path
[0062] A YAMAHA Inverter EF1000iS was modified to include a
carburetor bypass, a start module and thermal controller (a thermal
door), as illustrated in the figures. Furthermore, a larger
carburetor jet was used and the spark plug ignition timing was
retarded.
Example 2: Fuel Efficiency of 2 kW Flexible Fuel Generator Running
on JP-8 Fuel
[0063] FIG. 12 is a graph of the fuel consumption of a 2 kW
flexible fuel generator running on JP-8 fuel, in the normal and
econ modes, without a carburetor bypass air intake path
("unoptimized") or with a carburetor bypass air intake path with
the valve opened to maximize efficiency ("optimized").
Example 3: Combustion Efficiency and CO Emissions of a 1 kW
Flexible Fuel Generator
[0064] FIG. 13 is a graph of CO emissions for a 1 kW flexible fuel
generator running on JP-8 fuel with a fixed jet without a
carburetor bypass air intake path (squares), or with a carburetor
bypass air intake path (triangles), with the valve opened to
maximize efficiency. The dotted line represents the U.S. EPA limit
for a 50 cc engine.
[0065] FIG. 14 is a graph of combustion efficiency for a 1 kW
flexible fuel generator running on JP-8 fuel with a fixed jet
without a carburetor bypass air intake path (squares), or with a
carburetor bypass air intake path (triangles), with the valve
opened to maximize efficiency.
* * * * *