U.S. patent application number 16/191300 was filed with the patent office on 2019-10-24 for flexible fuel generator and methods of use thereof.
The applicant listed for this patent is INI Power Systems, Inc.. Invention is credited to Larry J. Markoski, Mack L. Nance, Timothy C. Simmons.
Application Number | 20190323424 16/191300 |
Document ID | / |
Family ID | 47595000 |
Filed Date | 2019-10-24 |
United States Patent
Application |
20190323424 |
Kind Code |
A1 |
Markoski; Larry J. ; et
al. |
October 24, 2019 |
FLEXIBLE FUEL GENERATOR AND METHODS OF USE THEREOF
Abstract
A portable flexible fuel generator, having an engine, includes:
a cylinder and a spark plug in the cylinder, a primary fuel tank
fluidly connected to the cylinder, an air intake path fluidly
connecting atmosphere to the cylinder, a start module including a
starting fuel tank holder and a starting fuel line, where the
starting fuel line is fluidly connected to the air intake path, a
coolant path which provide a flow path for coolant to cool the
cylinder, and a thermal controller along the coolant path.
Furthermore, the engine has full cylinder cooling.
Inventors: |
Markoski; Larry J.;
(Raleigh, NC) ; Simmons; Timothy C.; (Durham,
NC) ; Nance; Mack L.; (Raleigh, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INI Power Systems, Inc. |
Morrisville |
NC |
US |
|
|
Family ID: |
47595000 |
Appl. No.: |
16/191300 |
Filed: |
November 14, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14875441 |
Oct 5, 2015 |
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16191300 |
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14370374 |
Jul 2, 2014 |
9188033 |
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PCT/US2012/071042 |
Dec 20, 2012 |
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14875441 |
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13343597 |
Jan 4, 2012 |
9175601 |
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14370374 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01P 2025/32 20130101;
F02B 5/00 20130101; F02D 29/06 20130101; F01N 5/02 20130101; F01P
7/16 20130101; F02D 19/0649 20130101; B01D 1/0058 20130101; F01N
3/20 20130101; Y02T 10/30 20130101; F01N 13/08 20130101; F01N
2240/22 20130101; F02D 41/062 20130101; F02N 3/02 20130101; Y02T
10/20 20130101; H02K 7/1815 20130101; F02B 63/04 20130101; F02D
19/0615 20130101; F02N 99/00 20130101; F02B 2043/103 20130101; F02D
2400/06 20130101; F01N 2240/02 20130101; F02B 63/042 20130101; Y02T
10/12 20130101; F01N 3/103 20130101; F02B 43/10 20130101; Y10T
29/49231 20150115; F01N 3/005 20130101; F02B 69/02 20130101; C02F
1/16 20130101; F02D 41/0025 20130101; F02B 2201/064 20130101; F01N
2590/06 20130101; F01P 2007/146 20130101; Y02T 10/16 20130101; F02B
9/04 20130101; Y02T 10/36 20130101; F01P 2003/021 20130101; F01P
1/02 20130101; F02B 63/048 20130101; F02M 25/025 20130101; F02B
69/04 20130101 |
International
Class: |
F02B 63/04 20060101
F02B063/04; F02D 29/06 20060101 F02D029/06; F02D 19/06 20060101
F02D019/06; F01N 3/10 20060101 F01N003/10; F01N 5/02 20060101
F01N005/02; F02B 5/00 20060101 F02B005/00; F02B 69/02 20060101
F02B069/02; F02D 41/00 20060101 F02D041/00; F01P 7/16 20060101
F01P007/16; F01N 3/00 20060101 F01N003/00; F02N 3/02 20060101
F02N003/02; F02B 69/04 20060101 F02B069/04; F02N 99/00 20060101
F02N099/00; F02D 41/06 20060101 F02D041/06 |
Claims
1. A portable flexible fuel generator, having an engine,
comprising: (1) a cylinder, and a spark plug in the cylinder, (2) a
primary fuel tank, fluidly connected to the cylinder, (3) an air
intake path, fluidly connecting atmosphere to the cylinder, (4) a
start module, comprising a starting fuel tank holder and a starting
fuel line, wherein the starting fuel line is fluidly connected to
the air intake path, (5) a coolant path, which provide a flow path
for coolant to cool the cylinder, and (6) a thermal controller,
along the coolant path, wherein the engine has full cylinder
cooling.
2. The portable flexible fuel generator of claim 1, wherein the
generator is air-cooled.
3. The portable flexible fuel generator of any of claim 1, wherein
the cylinder has a compression ratio greater than 8:1.
4. The portable flexible fuel generator of claim 1, wherein the
generator does not include a battery.
5. The portable flexible fuel generator of claim 1, wherein the
cylinder comprises aluminum.
6. The portable flexible fuel generator of claim 1, further
comprising a generator housing enclosing the cylinder, wherein the
start module is attached to the generator housing.
7. The portable flexible fuel generator of claim 1, further
comprising a starting fuel tank, fluidly connected to the starting
fuel line.
8. The portable flexible fuel generator of claim 1, further
comprising a starting fuel dispenser, fluidly connecting the
starting fuel tank to the starting fuel line.
9-10. (canceled)
11. The portable flexible fuel generator of claim 1, wherein the
starting fuel tank contains a low-boiling point low-flashpoint
fuel.
12-13. (canceled)
14. The portable flexible fuel generator of claim 1, wherein an air
filter is present along the air intake path, and the starting fuel
line is connected to the air intake path between the air filter and
the cylinder.
15. The portable flexible fuel generator of claim 1, wherein: the
coolant path has an entrance for air to enter the generator and an
exit or air to exit the generator, the thermal controller is a
thermal door, and the thermal door is at the exit of the coolant
path.
16-18. (canceled)
19. The portable flexible fuel generator of claim 1, 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 has a compression ratio
greater than 8:1, the cylinder comprises aluminum, the generator
does not include a battery, the start module further comprises a
starting fuel enclosure, an air filter is present along the air
intake path, the starting fuel line is connected to the 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.
20. (canceled)
21. A method of generating electricity with a generator, the
generator having an engine comprising a cylinder and a spark plug,
the method comprising: operating the engine in the isothermal range
of 120-180.degree. C., and fueling the engine with a running fuel
comprising a heavy fuel.
22. The method of claim 21, wherein the heavy fuel is diesel
fuel.
23. The method of any of claim 21, further comprising starting the
engine while fueling the engine with a gaseous low-flashpoint
fuel.
24-30. (canceled)
31. A method of making a portable flexible fuel generator,
comprising modifying a portable gasoline generator, wherein the
modifying comprises: adding a starting module comprising a starting
fuel tank holder and a starting fuel line, wherein the stating fuel
line is fluidly connected to an air intake path of the portable
gasoline generator, adding a thermal door, along the coolant path
of the portable gasoline generator, and retarding the spark plug
ignition timing,
32. The method of claim 31, wherein the portable gasoline generator
is air cooled, has a compression ratio of greater than 8:1, does
not include a battery for starting the generator, and a cylinder of
the generator comprises aluminum.
33-38. (canceled)
39. The method of claim 31, wherein the modifying, further
comprises adding a starting fuel tank, fluidly connected to the
starting fuel line, and the starting fuel tank comprises
pressurized diethyl ether.
40. The method of claim 31, wherein: the portable gasoline
generator has a compression ratio greater than 8:1, uses fixed
timing, and has a 4 cycle, 50 cc engine, and the portable gasoline
generator comprises: a generator housing, an air filter along an
air intake path which supplied air for combustion of fuel, and a
coolant path having an entrance for air to enter the generator and
an exit for air to exit the generator, wherein the start module is
attached to the generator housing, the start module further
comprises a starting fuel enclosure, the starting fuel enclosure
comprises a starting fuel button access and starting fuel button
cover, the starting fuel line is connected to the air intake path
between the air filter and the cylinder, and the thermal door is at
the exit of the coolant path.
41-45. (canceled)
46. The method of claim 39, wherein the amount of diethyl ether for
starting the engine is 0.1 to 10 grams.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 13/343,597, filed Jan. 4, 2012 and entitled
"FLEX FUEL FIELD GENERATOR".
BACKGROUND
[0002] There has been a proliferation of small portable electronic
devices in recent years, most of which include onboard and/or
detachable rechargeable batteries. Examples include laptop
computers, mobile telephones, personal digital assistants, portable
digital cameras, global positioning systems, and hand-held radios.
The rechargeable batteries are most commonly lithium ion batteries,
although other varieties are available. The small portable
electronic devices typically include a removable power cord with a
standard two-prong or three-prong plug, or a universal serial bus
(USB) plug, for plugging into a corresponding plug receiver, which
allows for recharging the onboard batteries. Also commonly
available are removable power cords with a standard cigarette
lighter plug, for recharging the rechargeable batteries using a
cigarette lighter plug receiver in an automobile or other vehicle.
Also commonly available are multi-bay chargers for multiple
electronic devices and/or their detachable batteries with standard
two-prong or three-prong power cords. In general these devices
typically require less than 1 kW of recharging power whether from
AC or DC sources.
[0003] For field operation by consumers of portable appliances such
as televisions and radios, and small portable electronic devices
and recharging of the batteries therein, small portable
gasoline-only inverter generators have come into common use. The
advantage of using small portable gasoline-only inverter generators
is the much lower sound profile, lighter weight, and greater
efficiency for generating the small amount of electricity needed to
recharge batteries, over the period of time necessary for
recharging. Gasoline or petrol for the generator is readily
available at retail gasoline refueling stations.
[0004] Remote field operations, such as those in areas far away
from highways, retail outlets, and the electrical grid, require
participants to carry all supplies, especially consumable supplies,
which will be needed to complete the operations. Not only is the
total amount of supplies often minimized to reduce cost and weight,
but the variety of supplies is also minimized, to reduce logistical
costs and complexity in transporting materials to, and resupplying,
a base camp.
[0005] To get to remote field locations, off-road and military
tactical vehicles often utilize diesel-type heavy fuels, rather
than gasoline or petrol. The supplies carried to such remote field
locations typically only include heavy fuel, not gasoline, for the
vehicles as is common in the US military with it's one fuel forward
policy with a diesel type fuel (JP-8). In these cases, recharging
of batteries or batteries within electronic devices is typically
carried out using power generated by the vehicle, via idling the
vehicle main engine while recharging the batteries or from a large
2-10 kW heavy fuel generators towed or delivered on-site by the
vehicle or air support. Furthermore, in these remote and austere
field locations, the noise generated by the vehicles idling engine
or heavy fuel generator can be especially undesirable and often
exceeding 70 dB, considering the extended period of time needed for
recharging batteries or devices. Under these circumstances, the use
of heavy fuels and a heavy fuel generator or idling vehicle engine
is particularly inefficient for recharging small format batteries,
due to the poor match between the power generated and the power
required and consumed.
[0006] 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.
[0007] Gasoline and heavy fuel engines are products of distinct and
divergent technologies. 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. Improving the
combustion efficiency of a gasoline engine by increasing the
compression ratio further can result in autoignition ("knocking")
problems which interfere with operation and durability of the
aluminum engine.
[0008] Diesel fuel and kerosene (heavy fuels) have both high
flashpoints (greater than 35.degree. C.) and low autoignition
temperatures (below 200.degree. C.). A diesel engine relies on
compression induced autoignition to ignite the air/fuel mixture.
Although a compression ratio of 18:1 or 20:1 is necessary to start
and sustain reliable compression ignition, the superior combustion
efficiency provides cost and power advantages. Furthermore, the
high compression ratio requires that the fuel is sprayed into the
cylinders with a pump at 70 to 80 psi, atomizing the fuel to form
the liquid fuel/air mixture. The compression ignition engine cannot
typically be started at low to moderate temperatures without the
input of some form of high pressure from a fuel pump or thermal
energy from glow plugs or block heaters. The high compression ratio
requires stronger engine block materials and a heavy duty battery
to start the engine, making small portable devices unrealistic.
[0009] Diesel fuel and kerosene cannot be used directly in a
gasoline-only engine using a spark ignition. At ambient
temperatures a gasoline-only engine would not start if heavy fuels
are used. If somehow the engine were started, incomplete combustion
of the heavy fuel quickly floods the engine and fouls the lubricant
and spark plug. Unwanted autoignition ("knocking") is also
observed.
[0010] There exists vehicles that can be operated on both gasoline
and diesel fuel. An example is the "duce-and-a-half" or M35 cargo
truck. In this hypercycle, multi-fuel engine, a.very high
compression ratio is used: the very high compression ratio allows
for efficient autoignition of both gasoline and diesel fuel. The
very high compression ratio requires strong engine block materials
and a large engine and for the user to add oil to the gasoline in
order to maintain lubrication. Accordingly, this approach cannot be
used to create a portable generator.
SUMMARY
[0011] A portable flexible fuel generator, having an engine,
comprises: (1) a cylinder, and a spark plug in the cylinder, (2) a
primary fuel tank, fluidly connected to the cylinder, (3) an air
intake path, fluidly connecting atmosphere to the cylinder, (4) a
start module, comprising a starting fuel tank holder and a starting
fuel line, wherein the starting fuel line is fluidly connected to
the air intake path, (5) a coolant path, which provide a flow path
for coolant to cool the cylinder, and (6) a thermal controller,
along the coolant path. The engine has full cylinder cooling.
[0012] A method of generating electricity with a generator, the
generator having an engine comprising a cylinder and a spark plug,
comprises: operating the engine after start-up in the isothermal
range of 120-180.degree. C., and fueling the engine with a running
fuel comprising a heavy fuel.
[0013] A method of making a portable flexible fuel generator,
comprises modifying a portable gasoline generator. The modifying
comprises: adding a starting module comprising a starting fuel tank
holder and a starting fuel line, wherein the stating fuel line is
fluidly connected to an air intake path of the portable gasoline
generator; adding a thermal controller, along the coolant path of
the portable gasoline generator; and retarding the spark plug
ignition timing.
[0014] The portable flexible fuel generator may be made by
modifying a portable gasoline generator.
Definitions
[0015] 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.
[0016] 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.
[0017] Gaseous low-flashpoint fuels include hydrogen, syn gas,
propane and butane.
[0018] 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.
[0019] 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.
[0020] A "portable gasoline generator" is a generator that has an
internal combustion engine and includes a pull start 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
and the HONDA EU1000i.
[0021] 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.
[0022] 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".
[0023] The term "engine" means the internal combustion engine of a
generator, 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. Preferably the engine also contains a
lubricant.
[0024] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIGS. 1 and 2 illustrate a flexible fuel generator.
[0026] FIG. 3 illustrates a start module.
[0027] FIG. 4 illustrates starting fuel enclosure.
[0028] FIGS. 5 and 6 illustrate the interior of a start module,
with and without a starting fuel tank, respectively.
[0029] FIGS. 7 and 8 illustrate two configuration of the rear of a
flexible fuel generator, providing details of the thermal
controller.
[0030] FIG. 9 is an exploded view of a flexible fuel generator.
[0031] FIG. 10 illustrates a portion of the exploded view of the
flexible fuel generator shown in FIG. 9.
DETAILED DESCRIPTION
[0032] In order to develop a small portable generator which could
be operated on heavy fuels, preferably JP-8, it was necessary to
investigate in detail the sources of the problems which result from
using heavy fuel in a portable gasoline generator: (1) problems
starting the engine; (2) fouling of the lubricating oil; and (3)
engine knocking. The following were discovered during this
investigation.
[0033] Problems starting the engine were discovered to result from
the low volatility and low flashpoint of heavy fuels compared to
gasoline. Although gasoline is a mixture of various hydrocarbons
and other flammable liquids (such as ethanol) and additives, and
its composition is varied depending on the local weather conditions
(such as summer and winter formulations), it typically has an
initial boiling point of about 40.degree. C. and a flashpoint of
about -40.degree. C. In contrast, heavy fuel, such as JP-8, has a
boiling point above 150.degree. C. and a flashpoint of about
40.degree. C. When entering the cylinder of the engine, the
gasoline-air mixture will include a large amount of gasoline vapor.
The spark from the spark plug ignites this vapor, and the flame
front travels through the cylinder to quickly burn all the
gasoline. Because of the low flashpoint of heavy fuel, the spark
from the spark plug fails to ignite the fuel-air mixture. Even when
the heavy fuel is introduced in the engine pre-warmed above the
flashpoint of the heavy fuel, the low volatility of the heavy fuel
means that most of the heavy fuel is present as large droplets,
which incompletely burn or dissolve into the engine oil.
[0034] This incompletely burned heavy fuel collects in the engine.
The heavy fuel then begins to mix with the lubricant, which quickly
accumulates in the crank case. The low volatility of the heavy
fuel, exacerbated by the very low volatility of the lubricant,
prevents the heavy fuel from fully evaporating. The engine will
then begin to smoke and may seize-up due to cylinder flooding.
[0035] Knocking is caused by autoignition of the heavy fuels within
parts of the cylinder. After ignition by the spark, the burning
fuel creates a shock wave which travels through the cylinder and
moves the piston downward. The expanding shock wave moves faster
than the flame front of the burning fuel. Furthermore, some parts
of the cylinder, particularly at the exhaust exit, tend to be much
hotter than other parts of the cylinder. When the shock wave
reaches the rapidly heating end gas ahead of the flame front, the
heavy fuel ignites by autoignition from the increased pressure of
the shock wave and the ever-increasing temperature of the end gas,
causing destructive engine knocking.
[0036] The present invention is based on a variety of discoveries,
to address these problems. Together, they allow heavy fuels, in
particular diesel fuels such as JP-8 fuel, to be used in a modified
gasoline generator, creating a portable flexible fuel generator.
The portable flexible fuel generator incorporates the following
features: (1) 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; (2) a thermal controller, which
adjusts the cooling of the engine so that it operates at a range of
120-180.degree. C.; and (3) full cylinder air cooling, which cools
the entire cylinder, so that the temperature of the cylinder(s) is
maintained substantially uniform, without hot spot.
[0037] It has been discovered that a small amount of a low-boiling
point low-flashpoint fuel supplied to the air intake of the
generator, will allow starting of the engine with heavy fuels. A
small amount of the low-boiling point low-flashpoint fuel, from 0.1
to 10.0 grams, delivered anywhere along the air intake path, will
evaporate at an appropriate rate to allow starting and continued
operation of the engine with liquid heavy fuel. By the time the
low-boiling point low-flashpoint fuel has evaporated and been
consumed, the engine has reached an operating temperature
sufficient to sustain the combustion of the heavy fuel and to
provide the heat necessary to quickly bring the engine to the
isothermal range of 120-180.degree. C. and the engine will then
continue running using heavy fuel.
[0038] It has also been discovered that a spark ignition engine
will not accumulate incompletely burned diesel fuel when operated
at an isothermal range of 120-180.degree. C. The generator engine
of the present application is designed to operate in a "sweet
spot"--an engine operating temperature of 120-180.degree. C.--where
heavy fuels, such as JP-8 fuel, behave like gasoline. Within this
temperature window JP-8 fuel does not autoignite even at a
compression ratio of greater than 8:1, but does burn efficiently
when ignited by a spark from a spark plug. The temperature of
120-180.degree. C. of the fuel when it enters the cylinder(s) of
the engine ensures sufficient volatility to eliminate liquid fuel
accumulation, preventing flooding of the engine and fouling of the
lubricant. By redesigning the classic small gasoline powered
portable engine to run within this temperature window, the
generator engine may operate on gasoline, heavy fuel, and other
fuels and mixtures.
[0039] It has also been discovered that isothermal operation of an
engine, so that the temperature of the cylinder(s) is maintained
substantially uniform, without hot spot, prevents knocking. It was
believed that operating a generator at higher temperatures would
increase knocking, because the pressure needed to induce
autoignition is reduced at higher temperatures. However, it was
discovered that hot spots, which are at a temperature greater than
180.degree. C., are the true causes of autoignition, and therefore
more uniform cooling of the cylinder, especially at the exhaust
valve and piston head, reduces the unwanted autoignition of the
heavy fuel. This may be carried out by cooling the cylinder at the
fuel entrance and/or at the exhaust exit.
[0040] 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. The air intake path fluidly connects the
atmosphere outside the generator to the engine, to supply air for
combustion of the fuel. 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.
[0041] The air intake path is the path along which air enters the
generator housing and travels to the carburetor, when the fuel-air
mixture is formed and then delivered to the cylinder. Preferably,
the generator includes an air filter along the air intake path. The
starting fuel line, which may be a simple plastic tube resistant to
damage or chemical reaction from the low-boiling point
low-flashpoint fuel, preferably delivers the low-boiling point
low-flashpoint fuel as a mist to the air exit side (back) of the
air filter, or to some other point between the air filter and the
carburetor.
[0042] 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.
[0043] 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 the combustion of the heavy fuel. Because the low-boiling
point low-flashpoint fuel is provided along the 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 the 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.
[0044] 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.
[0045] A 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.
[0046] The 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 measure at the spark plug using a thermocouple
temperature sensor (for example, a spark plug temperature sensor
available from TRAIL TECH).
[0047] 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.
[0048] 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 must be 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.
[0049] 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.
[0050] The flexible fuel generator of the present application may
be prepared by modifying a portable gasoline generator, 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. 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. 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.
[0051] 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.
[0052] Examples of portable flexible fuel generators of the present
application are illustrated in the figures. The generator of the
present invention includes an internal combustion engine containing
a spark plug, a start module, full cylinder cooling and a thermal
controller. Other parts are optional.
[0053] FIGS. 1 and 2 illustrate a flexible fuel generator, 10. 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] FIG. 9 is an exploded view of a flexible fuel generator.
Here, the generator housing, 14 has been split apart to show
otherwise hidden elements. 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.
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. 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.
[0058] 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 couple 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.
EXAMPLE
[0059] A YAMAHA Inverter EF1000iS was modified to include 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.
* * * * *