U.S. patent number 3,807,377 [Application Number 05/174,015] was granted by the patent office on 1974-04-30 for fuel system.
This patent grant is currently assigned to Ethyl Corporation. Invention is credited to Daniel A. Hirschler, Jr., Frederick J. Marsee.
United States Patent |
3,807,377 |
Hirschler, Jr. , et
al. |
April 30, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
FUEL SYSTEM
Abstract
A dual liquid fuel system for an internal combustion gasoline
engine. The system delivers a volatile fuel to the carburetor or
other fuel metering system on start-up and until the engine attains
an operating temperature that does not normally require choking
when using a normal gasoline. The system then switches fuels and
delivers normal gasoline. The system includes means to partially
vaporize gasoline and condense the vapor to obtain the volatile
fuel used in start and warm-up.
Inventors: |
Hirschler, Jr.; Daniel A.
(Birmingham, MI), Marsee; Frederick J. (Clawson, MI) |
Assignee: |
Ethyl Corporation (Richmond,
VA)
|
Family
ID: |
26849759 |
Appl.
No.: |
05/174,015 |
Filed: |
August 23, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
152678 |
Jun 14, 1971 |
|
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Current U.S.
Class: |
123/575; 261/144;
261/18.3; 123/179.16 |
Current CPC
Class: |
F02M
31/18 (20130101); F02M 1/165 (20130101); F02B
1/04 (20130101); Y02T 10/126 (20130101); Y02T
10/12 (20130101) |
Current International
Class: |
F02M
1/00 (20060101); F02M 31/18 (20060101); F02M
1/16 (20060101); F02M 31/02 (20060101); F02B
1/04 (20060101); F02B 1/00 (20060101); F02m
013/00 () |
Field of
Search: |
;123/127,133,179G,134,2,3,18R,18A,18P,18AC ;196/98,104
;208/356,359,361,366 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Attorney, Agent or Firm: Johnson; Donald L. Linn; Robert A.
Odenweller; Joseph D.
Parent Case Text
This application is a Continuation-in-Part of application Ser. No.
152,678, filed June 14, 1971.
Claims
We claim:
1. A fuel system for a spark ignited internal combustion engine
having carburetor fuel induction means, said fuel system
comprising:
a. a container for liquid hydrocarbon fuel of the gasoline boiling
range connected by a liquid fuel conduit to the fuel inlet of said
carburetor,
b. a container for liquid hydrocarbon fuel of the lower gasoline
boiling range connected by a volatile liquid fuel conduit to said
fuel inlet of said carburetor,
c. valve means in said liquid fuel conduit and volatile liquid fuel
conduit adapted to:
1. close said liquid fuel conduit and open said volatile liquid
fuel conduit during start and warm-up of said engine, and
2. open said liquid fuel conduit and close said volatile liquid
fuel conduit after warm-up of said engine and
d. a vapor conduit connecting the top of said container for liquid
hydrocarbon fuel of the lower gasoline boiling range to the
normally liquid containing zone of said container for liquid
hydrocarbon fuel of the gasoline boiling range, said vapor conduit
having one-way pressure relief valve means adapted to permit vapor
to flow to said normally liquid containing zone whenever the
pressure in said container for liquid hydrocarbon fuel of the lower
gasoline boiling range rises above a predetermined pressure.
2. A fuel system of claim 1, said system including engine
temperature sensing means and valve actuating means, said
temperature sensing means being responsive to the engine
temperature such that when said temperature is below a
predetermined operating temperature said temperature sensing means
signals said valve actuating means to close said valve means in
said liquid fuel conduit and open said valve means in said volatile
liquid fuel conduit, and such that when said temperature rises to
said operating temperature said temperature sensing means signals
said valve actuating means to open said valve means in said liquid
fuel conduit and close said valve means in said volatile liquid
fuel conduit.
3. A fuel system of claim 1 wherein said container for liquid
hydrocarbon fuels of the gasoline boiling range is connected by a
second liquid fuel conduit to fuel vaporizing means adapted to
vaporize the light ends from said liquid hydrocarbon fuel of the
gasoline boiling range forming vaporized light ends and
volatile-depleted fuel, said vaporizing means being connected by a
vapor conduit to condensing means whereby said vaporized light ends
are condensed to form volatile fuel condensates, said condensing
means being connected by a volatile fuel condensate conduit to said
container for liquid hydrocarbon fuels of the lower gasoline
boiling range adapted to conduct said volatile fuel condensate to
said container for liquid hydrocarbon fuels of the lower gasoline
boiling range, said vaporizing means being connected by a
volatile-depleted fuel conduit to said container for liquid
hydrocarbon fuels of the gasoline boiling range adapted to conduct
said volatile-depleted fuel to said container for liquid
hydrocarbon fuel of the gasoline boiling range.
4. A fuel system of claim 3, said system including engine
temperature sensing means and valve actuating means, said
temperature sensing means being responsive to the engine
temperature such that when said temperature is below a
predetermined operating temperature said temperature sensing means
signals said valve actuating means to close said valve means in
said liquid fuel conduit and open said valve means in said volatile
liquid fuel conduit, and such that when said temperature rises to
said operating temperature said temperature sensing means signals
said valve actuating means to open said valve means in said liquid
fuel conduit and close said valve means in said volatile liquid
fuel conduit.
5. A fuel system of claim 4, having vapor pump means in said vapor
conduit adapted to pump said vaporized light ends to said
condensing means and volatile-depleted pump means in said
volatile-depleted fuel conduit adapted to pump said
volatile-depleted fuel back to said container for liquid
hydrocarbon fuel of the gasoline boiling range.
6. A fuel system of claim 5, having one-way valve means in said
volatile fuel condensate conduit adapted to permit said volatile
fuel condensate to flow to said container for liquid hydrocarbon
fuels of the lower gasoline boiling range and to prevent flow in
the reverse direction.
7. A fuel system of claim 6, having one-way valve means in said
volatile-depleted fuel conduit adapted to permit said
volatile-depleted fuel to flow to said container for liquid
hydrocarbon fuel of the gasoline boiling range and to prevent flow
in the reverse direction.
8. A fuel system of claim 7, having one-way pressure relief valve
means in said second liquid fuel conduit, said pressure relief
valve means adapted to open whenever the pressure on said fuel
vaporizing means side of said pressure relief valve is from about
3-10 psig lower than on the opposite side of said pressure relief
valve.
9. A fuel system of claim 8 having liquid level sensing means
responsive to the liquid level in said container for liquid
hydrocarbon fuel of the lower gasoline boiling range, said liquid
level sensing means functioning to signal said vapor pump means to
operate whenever said liquid level drops below a predetermined
level, said predetermined level being at least sufficient to
provide enough liquid hydrocarbon fuel of the lower gasoline
boiling range to start and operate said engine for a period of time
sufficient to bring its temperature to said operating
temperature.
10. A fuel system of claim 9, having volatile-depleted liquid level
sensing means responsive to the volatile-depleted liquid level in
said vaporizing means, said volatile-depleted liquid level sensing
means functioning to signal said volatile-depleted pump means in
said volatile-depleted fuel conduit to operate whenever said
volatile-depleted liquid level rises above a predetermined
level.
11. A fuel system of claim 1 having carburetor drain means adapted
to drain residual fuel from said carburetor to the storage
container for said liquid hydrocarbon fuel of the gasoline boiling
range when said engine is stopped and having carburetor drain valve
means in said carburetor drain means said carburetor drain valve
means being responsive to the electrical ignition system of said
engine such that when said ignition system is turned on said
carburetor drain valve means close, and when said electrical
ignition system is turned off said carburetor valve means open.
12. A fuel system of claim 5 comprising fuel vaporizing means
adapted to vaporize the light ends from said liquid hydrocarbon
fuel of the gasoline boiling range forming vaporized light ends and
volatile-depleted fuel, and condensing means whereby said vaporized
light ends are condensed to form said liquid hydrocarbon fuel of
the lower gasoline boiling range.
13. A fuel system for a spark ignited internal combustion engine
having carburetor fuel induction means, said fuel system
comprising:
a. a container for liquid hydrocarbon fuel of the gasoline boiling
range connected by a liquid fuel conduit to the fuel inlet of said
carburetor,
b. fuel vaporizing means adapted to vaporize the light ends from
said liquid hydrocarbon fuel of the gasoline boiling range forming
vaporized light ends and volatile-depleted fuel, said fuel
vaporizing means being connected to said container for liquid
hydrocarbon fuel of the gasoline boiling range by a second liquid
fuel conduit,
c. a container for volatile fuel condensate connected by a volatile
fuel conduit to said fuel inlet of said carburetor,
d. condensing means connected by a vapor conduit to said fuel
vaporizing means and by a volatile fuel condensate conduit to said
container for volatile fuel condensate, said condensing means being
adapted to condense said vaporized light ends to form said volatile
fuel condensate,
e. vapor pump means in said vapor conduit adapted to pump said
vaporized light ends to said condensing means,
f. a one-way check valve in the conduit from said fuel vaporizing
means to said container for volatile fuel condensate between said
vapor pump means and said container for volatile fuel condensate
adapted to permit flow to said container for volatile fuel
condensate and to prevent flow in the reverse direction,
g. valve means in said liquid fuel conduit and said volatile fuel
conduit adapted to:
1. close said liquid fuel conduit and open said volatile liquid
fuel conduit during start and warm-up of said engine, and
2. open said liquid fuel conduit and close said volatile liquid
fuel conduit after warm-up of said engine, and
h. a second vapor conduit connecting the top of said container for
volatile fuel condensate to the lower normally liquid containing
zone of said container for liquid hydrocarbon fuel of the gasoline
boiling range, said second vapor conduit having one-way pressure
relief valve means adapted to permit vapor to flow to said normally
liquid containing zone whenever the pressure in said container for
volatile fuel condensate rises above a predetermined pressure.
14. A fuel system of claim 13. having a volatile-depleted fuel
conduit connecting said vaporizing means to said container for
liquid hydrocarbon fuel of the gasoline boiling range adapted to
conduct said volatile-depleted fuel to said container for liquid
hydrocarbon fuel of the gasoline boiling range and one-way valve
means in said volatile-depleted fuel conduit adapted to permit said
volatile-depleted fuel to flow to said container for liquid
hydrocarbon fuel of the gasoline boiling range and to prevent flow
in the reverse direction.
15. A fuel system of claim 13 having a one-way pressure relief
valve in said second liquid fuel conduit, said pressure relief
valve adapted to open whenever the pressure on said fuel vaporizing
means side of said pressure relief valve is from about 3-10 psig
lower than on the opposite side of said pressure relief valve.
16. A fuel system of claim 13 including:
i. liquid level sensing means responsive to the liquid level in
said container for volatile fuel condensate, said liquid level
sensing means functioning to signal said vapor pump means to
operate whenever said liquid level drops below a predetermined
level, said predetermined level being at least sufficient to
provide enough volatile fuel condensate to start and operate said
engine for a period of time sufficient to raise its temperature to
operating temperature.
17. A fuel system of claim 16, having a volatile-depleted fuel
conduit connecting said vaporizing means to said container for
liquid hydrocarbon fuel of the gasoline boiling range,
volatile-depleted pump means in said volatile-depleted fuel conduit
adapted to pump said volatile-depleted fuel to said container for
liquid hydrocarbon fuel of the gasoline boiling range and
volatile-depleted liquid level sensing means responsive to the
volatile-depleted liquid level in said vaporizing means, said
volatile-depleted liquid level sensing means functioning to signal
said volatile-depleted pump means in said volatile-depleted fuel to
operate whenever said volatile-depleted liquid level rises above a
predetermined level.
18. A fuel system of claim 16, having carburetor drain means
adapted to drain residual fuel from the bowl of said carburetor to
said container for liquid hydrocarbon fuel of the gasoline boiling
range when said engine is stopped and having carburetor drain valve
means in said carburetor drain means, said carburetor drain valve
means being responsive to the electrical ignition system of said
engine such that when said ignition system is turned on said
carburetor drain valve means close and when said electrical
ignition system is turned off said carburetor valve means open.
Description
BACKGROUND
The exhaust gas of internal combustion engines contains various
amounts of unburned hydrocarbons, carbon monoxide, and nitrogen
oxides (NO.sub.x). Emission of these materials to the atmosphere is
undesirable. The problem is more acute in urban areas having a high
concentration of motor vehicles.
During recent years, researchers have investigated extensively
means of reducing exhuast emission. This research has been quite
fruitful. As a result, present-day automobiles emit but a fraction
of undesirable materials compared to those of less than a decade
ago. These improved results have come about through such means as
improved carburetion, ignition timing modification, exhaust
recycle, exhaust manifold air injection, use of lean air/fuel
ratios, positive crankcase ventilation, and the like.
Despite the tremendous advances that have been made, further
improvements are desirable. Federal standards by 1975 are expected
to require reduction of emissions to only about 10 percent of the
level of 1970. A major obstacle in achieving further reduction in
exhaust emissions is the fact that the engine requires a richer
air/fuel mixture during start and warm-up. During this period
exhaust emissions of even the lowest emitting engine is appreciably
increased. In the case of carburetor induction engines the required
richer air/fuel mixture is usually attained by placing a choke
valve in the air passage above the carburetor venturi, which serves
to restrict air flow. In most, but not all, gasoline-powered
vehicles the choke is automatically controlled by engine
temperature. As soon as the engine reaches an adequate operating
temperature (i.e., a temperature at which it can operate smoothly
without choking) the choke opens. In normal operation this takes
about 2-3 minutes.
In the past, attempts have been made to eliminate the need for this
rich operating warm-up period by operating the engine on liquid
petroleum gas (LPG) during the warm-up period and switching to
gasoline after operating temperature is attained. A drawback of
this system is that it requires the vehicle operator to obtain two
different kinds of fuel--gasoline and LPG.
An object of the present invention is to provide a fuel induction
system that results in lower exhaust emissions. A further object is
to provide a fuel induction system that allows an engine to start
and warm-up without the necessity of operating the engine at a rich
air/fuel ratio. A still further object of the invention is to
provide a dual liquid fuel system with self-generation of the more
volatile liquid fuel from the normal gasoline fuel, thus
eliminating the necessity of the vehicle operator obtaining two
separate fuels. Another object is to provide a method of operating
a gasoline engine in a manner that will result in reduced exhaust
emissions.
SUMMARY
The above and other objects are accomplished by providing a dual
liquid fuel system that will operate using a single liquid fuel
metering means. The system includes means for delivering both a
high volatility liquid fuel and normal gasoline to the engine fuel
metering system-- either carburetted or fuel injected. Volatile
fuel is delivered during start and warm-up and normal gasoline is
delivered when the engine attains an operating temperature that
allows smooth operation with normal gasoline at the lean air/fuel
ratios normally employed for warmed-up operation. Another way of
viewing this is that the fuel system allows start and warm-up of
the engine without carburetor choking.
The system includes means for draining residual gasoline from the
fuel metering system when the engine is turned off. In addition,
the system includes means for generating its own supply of volatile
fuel by partially vaporizing normal gasoline and condensing the
vapors.
A further object is to provide a dual fuel system that feeds
gasoline and gaseous fuel to the engine during selected periods of
operation. The gaseous fuel is obtained from the gasoline, thus
circumventing the need to fuel the vehicle with two separate
fuels.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic of the basic dual liquid fuel system showing
a reservoir for both volatile fuel and normal gasoline and conduits
for delivering either through a switching valve to the fuel bowl of
the carburetor. Also shown is a carburetor drain conduit having a
valve which allows the carburetor to drain when the engine is
turned off.
FIG. 2 is a cross-section of a carburetor having separate fuel
bowls for the normal gasoline and the volatile fuel and interlocked
valves for switching from one fuel to the other. The drawing shows
the valve functioning to permit delivery of the fuel from the
volatile fuel bowl such as would occur during start and
warm-up.
FIG. 3 is a schematic of the dual liquid fuel system showing its
connection to a carburetor on an internal combustion gasoline
engine. Also shown is an automatic fuel vaporizer and finned tube
condensing system for self-generation of the volatile fuel supply.
The drawing also shows liquid level controls in the vaporizer and
in the volatile fuel container which function to actuate pumps
which control the liquid level in the vaporizer and volatile fuel
container. Also shown are valves in the two fuel delivery conduits
for switching from one fuel to the other. Also included is a valved
drain line from the carburetor to the normal gasoline tank
permitting drain of residual fuel when the engine is turned
off.
FIG. 4 is a schematic of the dual liquid fuel delivery system
showing the vaporized fluid conduit wrapped around the vaporizing
chamber in a heat exhange relationship such that the heat evolved
on condensation of the vaporized light ends is transferred to the
fuel undergoing partial vaporization.
FIG. 5 is a schematic of another embodiment of the dual liquid fuel
delivery system showing the vaporizing chamber contained within the
gasoline tank and in contact with the normal gasoline. The vapor
conduit from the vaporizing chamber is also coiled within the
gasoline tank in contact with the normal gasoline which serves to
cool the vapor conduit and allow it to function as a condenser.
FIG. 6 is a schematic of the duel liquid fuel delivery system
showing the fuel vaporizer separate from the gasoline tank and
having the vapor conduit coiled within the vaporizing chamber
thereby transferring heat of condensation to the fuel undergoing
vaporization.
FIG. 7 is a schematic of the dual liquid fuel delivery system in
which the fuel vaporizer is jacketed and hot liquid from the engine
cooling system is circulated in the jacket to assist vaporization.
A finned-tube condensing system is shown.
FIG. 8 is a schematic of the dual liquid fuel delivery system
including a gasoline tank, vaporizing chamber, condenser, volatile
fuel storage tank and volatile-depleted fuel storage tank connected
to the gasoline conduit to permit feeding of the volatile-depleted
fuel directly to the carburetor fuel bowl rather than returning it
to the gasoline tank.
FIG. 9 is a schematic of a dual fuel system including a liquid fuel
carburetor and a gaseous fuel metering device. The gaseous fuel is
extracted from the normal gasoline in the vaporizer and stored in
the volatile fuel tank from which it is fed during specified
periods through pressure reduction valves and vaporizer to the
gaseous fuel metering device.
FIG. 10 is a cross-section of a typical gaseous fuel metering
device such as the one circled in FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a preferred embodiment of the invention is a
dual liquid fuel delivery system for a gasoline operated spark
ignited internal combustion engine having a gasoline tank 1 for
liquid hydrocarbon fuel of the gasoline boiling range (referred to
hereafter as normal gasoline) and a container for liquid
hydrocarbon fuel of the lower gasoline boiling range 2 (referred to
hereafter as volatile fuel).
Liquid hydrocarbon fuels of the gasoline boiling range are mixtures
of hydrocarbons having a boiling range of from about 80.degree. to
about 430.degree.F. as measured by ASTM method D-86. Of course,
these mixtures can contain individual constituents boiling above or
below these figures. These hydrocarbon mixtures contain aromatic
hydrocarbons, saturated hydrocarbons and olefinic hydrocarbons. The
bulk of the hydrocarbon mixture is obtained by refining crude
petroleum by either straight distillation or through the use of one
of the many known refining processes, such as thermal cracking,
catalytic cracking, catalytic hydroforming, catalytic reforming,
and the like. Generally, the final gasoline is a blend of stocks
obtained from several refinery processes. The final blend may also
contain hydrocarbons made by other procedures such as alkylate made
by the reaction of C.sub.4 olefins and butanes using an acid
catalyst, such as sulfuric acid or hydrofluoric acid.
Preferred gasolines are those having a Research Octane Number of at
least 85. A more preferred Research Octane Number is 90 or greater.
It is also preferred to blend the gasoline such that it has a
content of aromatic hydrocarbons ranging from 10 to about 60 volume
percent, an olefinic hydrocarbon content ranging from 0 to about 30
volume percent, and a saturate hydrocarbon content ranging from
about 40 to 80 volume percent, based on the whole gasoline.
In order to obtain fuels having properties required by modern
automotive engines, a blending procedure is generally followed by
selecting appropriate blending stocks and blending them in suitable
proportions. The required octane level is most readily accomplished
by employing aromatics (e.g., BTX, catalytic reformate, or the
like), alkylate (e.g., C.sub.8.sub.-9 saturates made by reacting
C.sub.4 olefins with isobutane using a HF or H.sub.2 SO.sub.4
catalyst), or blends of different types.
The balance of the whole fuel may be made up of other components
such as other saturates, olefins, or the like. The olefins are
generally formed by using such procedures as thermal cracking,
catalytic cracking and polymerization. Dehydrogenation of paraffins
to olefins can supplement the gaseous olefins occurring in the
refinery to produce feed material for either polymerization or
alkylation processes. The saturated gasoline components comprise
paraffins and naphthenes. These saturates are obtained from (1)
virgin gasoline by distillation (straight run gasoline), (2)
alkylation processes (alkylates) and (3) isomerization procedures
(conversion of normal paraffins to branched-chain paraffins of
greater octane quality). Saturated gasoline components also occur
in so-called natural gasoline. In addition to the foregoing,
thermally cracked stocks, catalytically cracked stocks and
catalytic reformates contain saturated components.
Utilization of non-hydrocarbon blending stocks or components in
formulating the fuels used in this invention is feasible and, in
some instances, may actually be desirable. Thus, use may be made of
methanol, tertiary butanol and other inexpensive, abundant and
non-deleterious oxygen-containng fuel components.
The normal gasoline may contain any of the other additives normally
employed to give fuels of improved quality, such as tetraalkyllead
antiknocks including tetramethyllead, tetraethyllead, mixed
tetraethyltetramethyllead, and the like. They may also contain
antiknock quantities of other agents such as cyclopentadienyl
nickel nitrosyl, methylcyclopentadienyl manganese tricarbonyl, and
N-methyl aniline, and the like. Antiknock promoters such as
tert-butyl acetate may be included. Halohydrocarbon scavengers such
as ethylene dichloride, ethylene dibromide and dibromo butane may
be adeed. Phosphorus-containing additives such as tricresyl
phosphate, methyl diphenyl phosphate, diphenyl methyl phosphate,
trimethyl phosphate, and tris(.beta.-chloropropyl)phosphate may be
present. Antioxidants such as 2,6-di-tert-butylphenol,
2,6-di-tert-butyl-p-cresol, phenylenediamines such as
N-isopropylphenylenediamine, and the like, may be present.
Likewise, the gasoline can contain dyes, metal deactivators, or any
of the additives recognized to serve some useful purpose in
improving the gasoline quality.
The liquid hydrocarbon fuel of the lower gasoline boiling range,
referred to as volatile fuel, are hydrocarbons having a final
boiling point below that of normal gasoline. In the present
invention it is not necessary to place an exact value on this final
boiling point and, in fact, it can vary when the dual fuel system
is used with different engines. The requirement is that the
volatile fuel have a final boiling point low enough such that the
particular engine to which the dual fuel system is connected will
start and operate smoothly during warm-up without resorting to a
richer air/fuel ratio than is required for operation at normal
operating temperature. This is not to say that the use of a richer
air/fuel ratio is excluded because under very cold conditions a
slightly richer mixture may be required, especially to start the
engine. This richer mixture is readily furnished by such means as
choking the engine. However, the amount of time that the enriched
air/fuel ratio is used will be substantially less than required
without the dual fuel system of this invention and, accordingly,
even when some choking is required, the overall exhaust emissions
will be still greatly reduced by the use of the dual fuel system of
this invention.
The optimum final boiling point for the volatile fuel to be used in
the dual fuel system on a particular engine is best determined
experimentally taking into account the conditions such as
temperature and humidity, etc., under which the engine will be
operated. A useful boiling range for the volatile fuel is from
about 60.degree.-300.degree.F. Especially good results are obtained
in most applications using a volatile fuel having a normal boiling
range of from about 70.degree.-150.degree.F. (ASTM D-86). The most
preferred volatile fuel is made up of the light ends (low boilers)
obtained from normal gasoline. In fact, further embodiments of this
invention, to be described in detail hereafter, include in the dual
liquid fuel system means for removing the light ends from normal
gasoline and using these as the volatile fuel during start and
warm-up.
Referring again to FIG. 1, the dual fuel system includes a liquid
fuel conduit 3 connecting gasoline tank 1 through fuel selector
valve 4 to fuel pump 5 which connects to fuel bowl 6 of carburetor
7. The carburetor shown is a single venturi type but the fuel
system is equally applicable to multiple venturi carburetors such
as those having 2, 3 or 4 venturi.
Volatile fuel tank 2 is connected by volatile liquid fuel conduit 8
to fuel selector valve 4 which connects through fuel pump 5 to fuel
bowl 6 of carburetor 7. As shown in FIG. 1, fuel selector valve 4
is set to deliver normal gasoline from gasoline tank 1 to
carburetor 7. By revolving the selector valve counter-clockwise, as
shown by the arrow, fuel selector valve 4 will function to deliver
volatile fuel from volatile fuel tank 2 to carburetor 7.
Fuel bowl 6 has a fuel drain 9 which can drain residual fuel from
fuel bowl 6 through drain conduit 10 to gasoline tank 1. Drain
valve 11 in drain conduit 10 is shown closed and is opened when it
is desired to drain fuel bowl 6.
In operation, the embodiment shown in FIG. 1 functions as follows.
Starting with a cold engine, fuel selector valve 4 is set to open
the flow path from volatile fuel tank 2 through fuel pump 5 to fuel
bowl 6. Fuel selector valve 4 may be set manually, but is
preferably positioned automatically in response to engine
temperature. A temperature responsive bimetal switch can be used to
signal valve actuating means to set fuel selector valve 4 to supply
the proper fuel to fuel bowl 6 depending upon a predetermined
engine temperature. The bimetal switch can be positioned to respond
to engine temperature at any of several locations such as
carburetor temperature, coolant temperature, oil temperature, or
multiple bimetal switches can be used to respond to temperature at
more than one location, thus requiring more than one location to
attain a predetermined operating temperature before the circuit is
completed to signal the valve actuating means to switch fuel
selector valve 4 from one fuel to another. The predetermined
temperature should be such that when the selector valve 4 is
signalled to switch from delivering fuel from volatile fuel tank 2
to normal gasoline tank 1 the engine will operate smoothly with
little, or preferably no, enrichment in the air/fuel ratio by means
such as choking. This operating temperature need not be the final
normal operating temperature of the engine but, rather, an
intermediate temperature somewhere between the cold engine and the
final operating temperature. The operating temperature at which
selector valve 4 switches from volatile fuel to normal gasoline
approximates the same temperature at which the well-known automatic
choking in a conventional fuel system would open because, in
essence, the delivery of the volatile fuel replaces, or
substantially replaces, the use of the choke.
When the engine starter is engaged, fuel pump 5 fills fuel bowl 6
with volatile fuel. This is delivered through fuel nozzle 12 to
carburetor venturi 13 where it is mixed with air and inducted into
the engine. By the use of the present fuel system, nozzle 12
delivers fuel at a leaner air/fuel ratio than would otherwise be
required to start the engine using normal gasoline. For example,
the engine can be started at air/fuel ratios of about 13-17:1
whereas conventional systems require a much richer ratio. Under
very adverse conditions, such as very low temperature, only minimal
enrichment may be required to allow the engine to start and operate
smoothly during warm-up.
When the engine reaches an operating temperature at which it can
operate smoothly on normal gasoline with little or no choking,
selector valve 4 is switched such that it closes the path from
volatile fuel tank 2 and opens the path from normal gasoline tank 1
such that fuel bowl 6 is supplied with normal gasoline. As
mentioned above, this can be accomplished manually but is
preferably accomplished automatically in response to engine
temperature.
After the engine has operated using normal gasoline and is turned
off fuel bowl 6 will contain residual normal gasoline. Once the
engine cools it will not start and run smoothly on this residual
normal gasoline without some enrichment of the air/fuel ratio-- in
other words, some choking would be required. To avoid this, fuel
bowl 6 is preferably drained after each use so that on the next
start-up the initial fuel supplied to the carburetor will be
volatile fuel. This is accomplished by opening drain valve 11
allowing the residual normal gasoline in fuel bowl 6 to drain
through drain conduit 10 to normal gasoline tank 1. Optionally, the
fuel bowl could drain to some other container provided for that
purpose. Opening of drain valve 11 can be accomplished manually but
preferably it is made automatic. One method of accomplishing this
is to provide valve actuating means such as an electrical solenoid
which keep valve 11 closed when the engine electrical engine system
is turned on and open valve 11 when the ignition system is turned
off. By this means when the engine is again started drain valve 11
will automatically close and either volatile fuel or normal
gasoline will be delivered to fuel bowl 6 depending upon engine
temperature.
Referring now to FIG. 2, another embodiment of the invention is
shown in which a dual fuel bowl carburetor 20 is provided which has
a fuel bowl for normal gasoline 21 and a separate fuel bowl for
volatile fuel 22. Selection of fuel delivered to carburetor venturi
23 is accomplished by interlocked valves 24 and 25. The
interlocking provides that when one valve is open the other is
closed. As shown, valve 25 is open and volatile fuel is being
delivered to venturi 23 which would be the proper selection at
engine start-up and warm-up. When the engine attains operating
temperature, valve 25 is closed and valve 24 opens such that normal
gasoline is delivered to venturi 23.
Valves 24 and 25 can be operated manually but are preferably
coupled with the previously-described engine temperature sensing
bimetal switch which was used to actuate valve 4 in FIG. 1. In this
manner, valve 25 will be automatically opened on start and warm-up.
When the engine attains smooth operating temperature, valve 25 will
automatically close and valve 24 will open. Valves 24 and 25 are
also interlocked with valve 26 in normal gasoline conduit 27 and
valve 28 in volatile fuel conduit 29 such that when valve 25 is
open valve 28 is open and valves 24 and 26 are closed. Likewise,
when the engine attains operating temperature and valve 24 opens
valve 26 also opens and valves 25 and 28 close.
In FIG. 2 each of fuel bowls 21 and 22 have individual fuel
delivery passages. In a similar arrangement the carburetor can be
modified such that only a single fuel delivery passage through a
main nozzle is provided for each venturi. This single nozzle is
supplied with fuel from either the volatile fuel bowl or the normal
gasoline bowl as required and the selection of which fuel is
delivered to the single nozzle is controlled by valves in the fuel
passage connecting the individual fuel bowls to the common nozzle.
These valves function in a manner similar to valves 24 and 25.
FIG. 3 shows the dual fuel system connected to an internal
combustion engine having carburetor fuel metering means. The system
includes an integral self-generation unit for obtaining volatile
fuel from normal gasoline. Gasoline tank 30 is connected by liquid
fuel conduit 31 to fuel inlet 32 of the carburetor. In fuel conduit
31 is fuel pump 33 and fuel selector valve 34. A second liquid fuel
conduit 35 connects gasoline tank 30 through one-way pressure
regulating valve 36 to the top of vaporizing chamber 37 which is
formed by a substantially cylindrical side wall and end closures.
Vaporizing chamber 37 is connected to the inlet of vapor compressor
38 by vapor conduit 39 entering vaporizing chamber 37 through the
top end closure. The outlet of compressor 38 is connected to the
inlet of finned tube condenser 30A. The outlet of condenser 30A is
connected by volatile fuel condensate conduit 31A through one-way
check valve 32A to spherical volatile fuel tank 33A. The bottom of
volatile fuel tank 33A is connected by volatile liquid fuel conduit
34A through fuel selector valve 35A to the fuel inlet 32 of the
carburetor. Located in conduit 34A is pressure regulating valve
38B. The top of volatile fuel tank 33A is connected through
pressure relief valve 36A by a second vapor conduit 37A back to
gasoline tank 30.
Vapor chamber 37 connects through its bottom end closure to the
inlet of volatile-depleted pump 38A. The outlet of pump 38A
connects through volatile-depleted fuel conduit 39A to gasoline
tank 30. Located in conduit 39A is one-way check valve 30B.
Drain conduit 31B connects a drain outlet at the bottom of the
carburetor fuel bowl such as drain 9 in FIG. 1 through valve 32B to
fuel conduit 31.
Bimetal thermo switch 33B responds to engine coolant temperature
and is connected by actuating means to valves 34 and 35A.
Located inside vaporizing chamber 37 is liquid level actuated
switch 34B which connects through the side wall of chamber 37 by
actuating means 36B to pump 38A.
Located inside volatile fuel tank 33A is liquid level actuated
switch 35B which is connected by actuating means 37B to pump
38.
In operation, starting with a cold engine, turning the ignition on
causes drain valve 32B to close. Thermo switch 33B responding to
the low engine temperature has valve 35A in an open position and
valve 34 in a closed position. Volatile fuel from volatile fuel
tank 33A flows through conduit 34A and fills the fuel bowl of the
carburetor. If required, an auxiliary fuel pump can be installed in
conduit 34A. This is not usually required because the volatile fuel
is under slight pressure which is regulated by pressure regulator
valve 38B such that the volatile fuel at the carburetor can be
controlled by a standard float actuated fuel bowl valve. Actuating
the starter starts the engine which operates without choking using
the volatile liquid fuel.
After 2-3 minutes of operation the liquid coolant temperature rises
to a predetermined level at which experience has shown the
particular engine can operate on normal gasoline without choking.
Thermo switch 33B senses this temperature and actuates valve 35A to
close and valve 34 to open. During continued operation normal
gasoline is supplied to the carburetor from gasoline tank 30
through fuel conduit 31.
Assuming the liquid level in volatile fuel tank 33A has dropped
below a predetermined level (this predetermined level should
provide enough reserve volatile fuel to start and warm-up the
engine), liquid level actuated switch 35B closes which starts pump
38. Pump 38 evacuates vaporizing chamber 37 pumping the residual
vapor therein towards condenser 30A. When the pressure in chamber
37 drops to a predetermined level pressure regulating valve 36
opens and meters normal gasoline from gas tank 30 through conduit
35 into evacuated vaporizing chamber 37. The predetermined pressure
differential which causes pressure regulating valve 36 to open is
such that the light ends of the normal gasoline will vaporize. A
useful pressure differential is that which will cause up to about
10-50 per cent of the normal gasoline to vaporize. The normal
gasoline thus admitted to the vaporizing chamber is partially
vaporized due to the reduced pressure. The vapors formed are pumped
by pump 38 towards condenser 30A where they compress and liquefy
releasing heat which is radiated by the finned-tube condenser 30A.
The condensate so formed is pumped through one-way check valve 32A
into volatile fuel tank 33A. If non-condensables are included in
the condensate and cause the pressure in volatile fuel tank 33A to
rise above about 5-75 psig, pressure relief valve 36A opens and
vents the non-condensables back to gas tank 30 until the pressure
in volatile fuel tank 33A drops to an acceptable level.
As fuel continues to be sucked into vaporizing chamber 37 the
volatile-depleted portion of the fuel collects at the bottom of
chamber 37. When the liquid level in chamber 37 reaches a
predetermined level, liquid level actuated switch 34B closes
causing pump 38A to operate which pumps the volatile-depleted fuel
through volatile-depleted conduit 39A and one-way check valve 30B
to gas tank 30.
When the liquid level in volatile fuel tank 33A rises to a
satisfactory level switch 35B turns off pump 38. As soon as the
liquid level in vaporizing chamber 37 drops below the predetermined
level switch 34B shuts off pump 38A. At this stage the
self-generation of volatile fuel is completed.
When the engine is stopped by turning off the ignition, drain valve
32B opens and drains the fuel bowl and valve 35A remains closed, or
if open, closes to prevent volatile fuel from entering the fuel
bowl while drain valve 32B is open. If the engine is restarted
while still above operating temperature valve 32B will close, and
since thermo switch 33B is still sensing adequate operating
temperature, valve 35A will remain closed and valve 34 will be
open. Hence, the carburetor will be supplied with normal gasoline.
However, if the engine remains off long enough to lower the engine
temperature below operating temperature, then valve 35A will open
and valve 34 will be closed and the sequence will be as described
above for starting a cold engine.
It is desirable to include in the vehicle an override system which
cuts out the automatic fuel switch control by engine temperature.
This is to handle the situation in which the engine is cold and
thermo switch 33B is signaling valve 35A to open and deliver
volatile fuel to the carburetor bowl during a period when the
volatile fuel supply in tank 33A has been depleted. In this event,
the automatic system is cut-out and normal gasoline is delivered to
the carburetor and the engine started in the conventional manner
using a choke.
In another aspect of the invention it may be desirable to control
the ratio between the pumping volumes of pumps 38 and 38A so as to
correspond to the ratio between the volumes of vapor and
volatile-depleted fuel formed in vaporizing chamber 37. In this
manner, pumps 38 and 38A operate concurrently. Similarly, by
control of vacuum regulating valve 36 and the pumping rates of
pumps 38 and 38A, both the rate at which volatile fuel is separated
from the whole gasoline and the distillation range of the volatile
fuel can be regulated.
FIGS. 4-6 show embodiments of the invention similar to that of FIG.
3 except that the volatile fuel self-generation system is modified
to provide heat exchange from the condenser to the vaporizer.
Partial vaporization of the normal gasoline by vacuum causes the
gasoline undergoing vaporization to cool, thus interferring with
the degree of vaporization attained with a given vacuum. Likewise,
on compressing the vaporized light ends in the condenser the
condensate and vapors increase in temperature due to heat released
on condensation. This interferes with the condensation and requires
higher condensing pressures. The modifications shown in FIGS. 4-6
tend to cancel out these effects.
In FIG. 4, gasoline tank 40 is connected to the fuel inlet of the
engine carburetor (not shown) by liquid fuel conduit 41 in the same
manner as in FIG. 3. Second liquid fuel conduit 42 connects
gasoline tank 40 with vaporizing chamber 43 through one-way
pressure regulating valve 44. In making this connection, second
liquid fuel conduit 42 utilizes a portion of liquid fuel conduit 41
because the gasoline tank 40 is normally located at the rear of the
vehicle whereas the vaporizing chamber 43 is normally located in
the engine compartment at the front of the vehicle. Since both the
liquid fuel conduit and the second liquid fuel conduit function to
supply normal gasoline, it is more practical to utilize a common
conduit from the rear gasoline tank up to the engine
compartment.
Vapor conduit 45 connects vaporizing chamber 43 through its upper
end closure to the inlet of compressor 46. The outlet of compressor
46 connects to condenser 47 which is a conduit helically coiled
around the outside of the cylindrical side wall of vaporizing
chamber 43 and is in contact with this side wall. FIG. 4 shows only
three turns of condenser conduit 47 around vaporizer 43, but there
can be as many turns as are required to obtain the required heat
exchange from the condenser 47 to the vaporizer 43.
From condenser 47 condensate conduit 48 connects to volatile fuel
tank 49 through one-way check valve 40A. Vapor conduit 41A connects
the top of volatile fuel tank 49 to gas tank 40 through pressure
relief valve 42A.
Vaporizing chamber 43 is connected through its bottom closure to
pump 43A which in turn connects by volatile-depleted fuel conduit
44A through one-way check valve 45A to gas tank 40.
The embodiment shown in FIG. 4 operates in the same manner as that
shown in FIG. 3. Pumps 46 and 43A are actuated by liquid level
sensors as in FIG. 3. Efficiency of the vaporizer-condenser system
is improved by the heat exchange coupling of the two functions.
In the embodiment of FIG. 5 the vaporizing chamber is placed inside
the normal gasoline tank such that the normal gasoline is in
contact with the side wall and bottom closure defining the
vaporizing chamber. Gasoline tank 50 is connected in the normal
manner to the carburetor fuel inlet by fuel conduit 51. Second fuel
conduit 52 connects gas tank 50 through pressure regulating valve
53 to vaporizing chamber 54 through its top end closure. Vapor
conduit 55 connects the top of chamber 54 to the inlet of
compressor 56. The outlet of compressor 56 connects by conduit 57
through the wall of gasoline tank 50 to the condensing coils 58
located in the space within gasoline tank 50 and outside vaporizing
chamber 54. Condenser coils 58 then connect by condensate conduit
59 through the wall of gasoline tank 50 to the volatile fuel tank
in the manner shown in FIGS. 3 and 4.
Through the bottom end closure of chamber 54 volatile-depleted
conduit 50A connects to the inlet of pump 51A. The outlet of pump
51A connects through one-way check valve 52A to gasoline tank 50.
As shown, pump 51A and valve 52A are outside gasoline tank 50,
which necessitates conduit 50A passing through the wall of gasoline
tank 50 to reach pump 51A. Pump 51A can be a sealed unit placed
within tank 50.
The embodiment shown in FIG. 5 operates in the same manner as that
in FIG. 3. Pumps 56 and 51A are actuated by liquid level sensors in
the volatile fuel tank and vaporizing chamber, respectively, as
explained previously.
FIG. 6 shows another embodiment of the volatile fuel
self-generation system. Gasoline tank 60 is connected in the normal
manner to the fuel inlet of the engine carburetor (not shown) by
fuel conduit 61. Second fuel conduit 62 connects gasoline tank 60
to vaporizing chamber 63 passing through pressure regulating valve
64. Vapor conduit 65 connects the top portion of vaporizing chamber
63 to the inlet of compressor 66. The outlet of compressor 66
connects by conduit 67 through the side wall of vaporizing chamber
63 to condensing conduit 68 coiled inside vaporizing chamber 63.
Condensing conduit 68 connects by condensate conduit 69 out through
the said wall of chamber 63 to the volatile fuel tank in the same
manner as shown in FIGS. 3 and 4.
Vaporizing chamber 63 connects through its bottom end closure by
volatile-depleted conduit 63A to pump 64A which then connects by
conduit 65A to gasoline tank 60. One-way check valve 66A is located
in conduit 65A.
Operation of the embodiment of FIG. 6 is the same as that of FIG.
3. Liquid level sensing means (not shown) in the volatile fuel tank
signal compressor 66 to operate when the liquid level in the
volatile tank drops below a predetermined level. Compressor 66
evacuates chamber 63 causing pressure regulating valve 64 to admit
normal gasoline into vaporizing chamber 63. The volatile portion of
the gasoline is vaporized and the vapors compressed into condensing
coils 68 where they form condensate and evolve heat which serves to
help vaporize the normal gasoline admitted to the vaporizing
chamber. The condensate is forced into the volatile fuel tank. Any
uncondensables that build up in the volatile fuel tank are returned
to gasoline tank 60 through a pressure relief valve as shown in
FIGS. 3 and 4.
A rise in the liquid level in vaporizing chamber 63 causes a liquid
level sensor (not shown) to signal pump 64A to operate by pumping
the volatile-depleted fuel back to gasoline tank 60 through conduit
65A and one-way check valve 66A.
Both normal gasoline and volatile gasoline are delivered to the
engine carburetor through fuel switching means that deliver
volatile fuel on start and warm-up and normal gasoline after the
engine attains an adequate operating temperature as described in
the embodiment of FIG. 3.
In the embodiment shown in FIG. 7 a supplemental heat source is
used to vaporize the gasoline. In FIG. 7, gas tank 70 connects by
fuel conduit 71 to the fuel inlet of the engine carburetor (not
shown). A second fuel conduit 72 connects gasoline tank 70 through
pressure regulating valve 73 to vaporizing chamber 74. Vaporizing
chamber 74 is formed by substantially cylindrical wall 75 and end
closures 76 and 77. The vaporizing chamber is jacketed by providing
an outer substantially cylindrical wall 78 and end closures 79 and
70A which form a closed annular space 71A between side wall 75 and
outer wall 78. Liquid coolant is conducted by standard means from
the engine and enters annular space 71A through inlet 72A in outer
wall 78 wherein it circulates. The liquid coolant leaves annular
space 71A through exit 73A from where it is conducted back to the
engine cooling system.
Vapor conduit 74A connects the top of vaporizing chamber 74 through
end closure 76 to compressor 75A. The outlet of compressor 75A
connects to finned tube condenser 76A. The outlet of finned tube
condenser 76A connects through one-way check valve 77A to volatile
fuel tank 78A. The bottom of tank 78A connects by volatile fuel
conduit 79A to the inlet of the engine carburetor (not shown) in
the manner described in FIG. 3. The top of fuel tank 78A connects
through pressure relief valve 70B and vent conduit 71B to gasoline
tank 70.
Vaporizing chamber 74 connects through bottom end closure 77 by
volatile-depleted conduit 72B to pump 73B. The outlet of pump 73B
connects by conduit 74B through one-way check valve 75B to gasoline
tank 70.
The embodiment of FIG. 7 operates in substantially the same manner
as that of FIG. 3. It differs in the addition of supplemental heat
to the vaporizing chamber by the engine coolant. Since the system
operates most efficiently after the engine liquid is hot, it is
preferred to include in this embodiment a thermo switch responsive
to engine coolant temperature that prevents operation of pump 75A
until the engine coolant is heated to a temperature adequate to
vaporize the light ends of the normal gasoline. Since the initial
boiling point of normal gasoline is about 80.degree.F., it is
generally satisfactory to set the thermo switch to permit pump 75A
to operate when the coolant reaches a temperature of about
130.degree.F.
In another embodiment of the invention hot exhaust gas is used to
supply the supplemental heat to the vaporizing chamber of the
engine coolant. In this embodiment an exhaust shunt is provided in
the exhaust system which diverts hot exhaust gas to the vaporizing
chamber whenever the liquid level sensor in the volatile fuel tank
78A is actuated by a low liquid level to signal operation of pump
75A.
In further embodiments, the heat used to vaporize the light-end of
the gasoline delivered to vaporizing chamber 74 is supplied by
other vehicle heat sources such as the crankcase lubricant,
transmission fluid, and the like.
In general, it is preferred to maintain the volatile liquid fuel in
the vapor liquid fuel tank under moderate pressure to avoid loss by
evaporation. A pressure range of from about 5 to 75 psig is
generally adequate for this purpose. However, under conditions in
which the volatile fuel tank is exposed to high temperatures such
as those in the engine compartment, higher pressure may be
desirable. When the volatile liquid fuel is maintained under
pressure it is preferred to include in the volatile liquid fuel
conduit a pressure reduction valve such that the pressure of the
volatile liquid fuel delivered to the inlet of the carburetor fuel
bowl is low enough so that it can be readily metered into the fuel
bowl by a fuel bowl float actuated valve.
The embodiment in FIG. 8 includes a gasoline tank 80 connected by
fuel conduit 81 through valve 82, pump 83 and valve 84 to the fuel
inlet of fuel bowl 85 of a liquid fuel carburetor. Second fuel
conduit 86 connects through pressure regulating valve 87 to
vaporizer 88 formed by a circular side wall and end closures. As
shown, the bottom end closure is in the form of an inverted cone.
The top end closure may also be conical in order to better
withstand the vacuum which is generally maintained within the
vaporizer. Vaporizer 88 connects by volatile fuel conduit 89
through its top end closure to pump 80A, which in turn connects to
condensing tube 81A coiled within vaporizer 88. Condensing tube 81A
connects through condensate conduit 82A and pressure regulating
valve 83A to volatile fuel tank 84A, which is spherical to
withstand substantial internal pressure. Inside tank 84A is liquid
level actuated switch 85A which is electrically connected to pump
80A. The top of tank 84A connects through vapor conduit 86A and
pressure relief valve 87A to gasoline tank 80. The bottom of tank
84A connects through volatile fuel conduit 88A, pressure regulating
valve 89A and valve 80B to the fuel inlet of fuel bowl 85. FIG. 8
does not show the fuel bowl drain as shown in FIGS. 1 and 3, but
this feature is preferably included.
In operation starting with a cold engine both valve 84 and 80B are
closed. When the ignition is turned on, valve 80B opens in response
to temperature sensors installed in the engine and fuel bowl 85
fills with volatile fuel delivered from tank 84A through conduit
88A and pressure regulating valve 89A. Valve 89A reduces the
pressure from that in volatile fuel storage tank 84A (approximately
5-75 psig) to a pressure that can be controlled by the float
actuated valve in fuel bowl 85. This reduced pressure is generally
about 1-5 psig.
The engine starts readily on the volatile fuel without any choking
and warms toward normal operating temperature. When the engine
temperature sensors reach a temperature at which experience has
shown the engine will operate satisfactorily on normal gasoline
without choking, they signal valve 84 to open and valve 80B to
close. Normal engine operation continues using gasoline.
The resultant reduction in the liquid level in tank 84A is detected
by liquid level switch 85A which starts pump 80A. Pump 80A may be
electrically driven or may be belt driven by the engine. Pump 80A
functions to remove fuel vapor from vaporizer 88 and compresses it
into condensing tube 81A wherein it is cooled and condensed to form
volatile fuel condensate. When the pressure in condensing tube 81A
reaches a predetermined level which is above the pressure in tank
84A and adequate to cause the fuel vapor to condense, pressure
regulator valve 83A allows a controlled amount of the condensate to
pass through conduit 82A into tank 84A, thus replenishing the
supply of volatile fuel. Alternatively, valve 83A may be a one-way
check valve which passes condensate into tank 84A as soon as its
pressure exceeds that in tank 84A.
As a result of pump 80A, the pressure in vaporizer 88 drops, and at
a predetermined level between about 1-14 psig, pressure regulator
valve 87 opens and meters gasoline from gasoline tank 80 through
second fuel conduit 86 into vaporizer 88 at a rate adequate to
maintain the predetermined vacuum in vaporizer 88 at a
substantially constant level. A spray nozzle can be attached at the
outlet of conduit 86 inside vaporizer 88.
When the gasoline enters vaporizer 88 it is partially vaporized
furnishing additional vapors to pump 80A. The volatile-depleted
fuel drops to the bottom of vaporizer 88 where it serves to cool
condenser tube 81A. If desired, additional heat can be supplied to
vaporizer 88 to assist vaporization by such means as electrical
heaters or, preferably, by a jacket through which hot coolant or
exhaust from the engine is passed.
The amount of volatiles removed from the gasoline to form volatile
condensate depends to a large extent on the composition of the
fuel. Fortunately, in cold months when a larger amount of volatile
condensate will be required, there is a greater proportion of such
volatile components (e.g., butanes, pentanes, hexanes) in the
gasoline. The degree to which the gasoline is stripped of volatiles
is best determined experimentally. A useful guide is to remove a
volatile fraction having a boiling range (ASTM D-86) up to about
300.degree.F., more preferably up to about 150.degree.F. Individual
components of the condensate, for example, butanes and pentanes,
may individually boil from about -10.degree.F. (isobutane) to about
96.degree.F. (n-pentane). These low boiling components are very
effective in eliminating the need for choking the engine.
The volatile-depleted fuel collects at the bottom of vaporizer 88.
In a highly preferred embodiment this volatile-depleted fuel is not
returned to gasoline tank 80 but is instead stored in a
volatile-depleted fuel tank 81B, and when available, is used to
operate the engine whenever it is at normal operating temperature.
When the engine is at its normal operating temperature it can
operate efficiently on such volatile-depleted fuel without any
substantial increase in exhaust hydrocarbon or carbon monoxide
emission. In this manner, the accumulation of volatile-depleted
fuel in gas tank 80 is avoided, thus assuring that the gasoline
will contain a sufficient amount of volatile components to allow
efficient operation of the vaporizer. The fuel system of the
present invention will operate effectively without this improved
feature but generally will provide volatile condensate for about
20-50 cold starts per each 20 gallon tank of gasoline before the
volatile level in the gasoline becomes too low to permit efficient
operation of the vaporizer.
Pump 82B is started when the liquid level in vaporizer 88 attains a
predetermined level, which level still permits efficient operation
of the vaporizer. This level is readily detected by a liquid level
actuated switch (not shown) which starts pump 82B. Pump 82B pumps
the volatile-depleted fuel through conduit 83B and one-way check
valve 84B into tank 81B. This tank may be vented since the fuel
stored therein has been stripped of its volatile components. Liquid
level switch 85B functions to keep valves 86B open and 82 closed
when there is volatile-depleted fuel available in tank 81B to
operate the engine. As a safety item, switch 85B, when it senses
that tank 81B is full to capacity, will open both valves 86B and 82
allowing volatile-depleted fuel to drain back to gas tank 80 until
a safe level is attained in tank 81B, at which time switch 85B
closes valve 82. When the liquid level in tank 81B drops to about
empty, switch 85B closes valve 86B and opens valve 82 allowing the
engine to operate on gasoline from gas tank 80.
As a further embodiment, valves 86B and 82 can function such that,
rather than completely closing valve 82 when volatile-depleted fuel
is available in tank 81B, it is only partially closed, thus mixing
gasoline from tank 80 with the volatile-depleted fuel from tank 81B
in a ratio that gives improved engine operation.
FIG. 9 shows another embodiment of the invention in which a highly
volatile condensate is removed from gasoline and used as the fuel
source for a gaseous fuel metering system. In other words, in this
embodiment there are two fuel metering systems -- one metering
liquid fuel and the other metering gaseous fuel. When it is stated
herein that a particular embodiment has a single fuel metering
system, it is meant that the system employs only one type of
metering, e.g., liquid fuel metering. Of course, in performing this
fuel metering function a plurality of means may be employed. For
example, the fuel system may be fuel injected or carburetted.
Likewise, the carburetor may have a single fuel nozzle per venturi
or may have a plurality of fuel nozzles per venturi. Likewise, the
carburetor may be single venturi or may be multiple venturi such as
a 2, 3 or 4 venturi carburetor. Also, more than one carburetor may
be used on a single engine to gain improved volumetric efficiency.
The common feature is that in all these embodiments only a liquid
fuel metering system is employed. In the embodiment now to be
described two fuel metering systems are employed -- one a liquid
fuel metering system (e.g., fuel injector, carburetor) and the
other a gaseous fuel metering system of the type commonly used in
LPG fueled engines.
The embodiment shown in FIG. 9 comprises gasoline tank 90 connected
by fuel conduit 91 through valve 92 and fuel pump 93 to fuel bowl
94 of carburetor 95 mounted on the intake manifold of an internal
combustion engine. Valve 95E is the passage between the fuel jet
and nozzle. Tank 90 connects through conduit 96 and pressure
regulating valve 97 to first vaporizer 98. Vaporizer 98 connects
through vapor conduit 99 and pump 90A to condensing tube 91A.
Vaporizer 98 is jacketed by housing 91B which provides a plenum
space 92B between the vaporizer housing and the jacket housing.
Jacket housing 91B has an entry port 93B and exit port 94B to the
plenum space 92B.
Condensing tube 91A connects through condensate conduit 95B and
pressure regulating valve 96B to volatile fuel tank 97B. The top of
volatile fuel tank 97B is vented through pressure relief valve 98B
and vapor conduit 99B to the bottom area of gasoline tank 90.
Located within tank 97B is liquid level actuated switch 90C.
The bottom of tank 97B connects through conduit 91C and first
pressure reducing valve 92C to second vaporizer 93C which is formed
by housing 94C. Outer housing 95C provides a heating jacket for the
second vaporizer 93C which has an inlet 96C and outlet 97C for a
heating material. Vaporizer 93C also has a drain conduit 98C
through valve 99C.
The top of second vaporizer 93C connects through second pressure
reduction valve 90D and conduit 91D to a standard gaseous fuel/air
metering device 92D. Air enters metering device 92D through air
inlet 93D and the gaseous fuel/air mixture is conducted to the air
intake 93E of carburetor 95.
The bottom of first vaporizer 98 connects through pump 96D,
volatile-depleted fuel conduit 97D and one-way check valve 98D to
volatile-depleted fuel tank 99D. Within tank 99D is liquid level
actuated switch 90E. The bottom of tank 99D connects through valve
91E and fuel pump 93 to fuel bowl 94 of carburetor 95 mounted on
the intake manifold of an internal combustion engine.
FIG. 10 is a cross-section of a typical air/vapor fuel metering and
mixing device. It comprises fuel vapor conduit 100 which connects
to mixing zone 101 through circular orifice 102. Air enters inlet
103 and enters mixing zone 101 at circular orifice 104. Valve
member 105 is attached to diaphragm 106 and can move up and down
and seats on circular orifices 102 and 104. Spring 107 presses
valve member 105 against orifices 102 and 104. When throttle valve
92E opens and valve 94E is closed pressure drops in mixing zone
101. The pressure drop is equalized to actuating chamber 108 by
ports 109 in valve member 105. Since the effective area in chamber
108 is greater than the area between orifices 102 and 104, valve
member 105 lifts, allowing air and fuel vapor to enter the mixing
zone. The ratio of air to fuel is controlled by the relative size
of orifices 102 and 104 and by the vapor pressure in conduit 100
which is regulated by valve 90D, generally at slightly below
atmospheric pressure.
In operation starting with a cold engine, thermoswitches mounted on
the engine sense the low temperature condition and function to
close valve 94E and 95E and to open valve 95D. Cranking the engine
reduces pressure in conduit 94D and inducts a mixture of gaseous
fuel and air from metering device 92D. Second regulating valve 90D
opens to meet demand and permits fuel vapor from tank 93C to enter
metering device 92D. In practice, the fuel vapor pressure in
conduit 91D is maintained slightly below atmospheric in case an
accidental leak downstream of regulating valve 90D. When pressure
in second vaporizer 93C starts to drop, liquid volatile fuel from
tank 97B is admitted to vaporizer 93C through first pressure
regulating valve 92C. This valve is adjusted to maintain a
satisfactory amount of fuel in second vaporizer 93C in the gaseous
form at ambient temperatures to at least start the engine. A useful
pressure range in second vaporizer 93C is from about 1-15 psig. In
extreme cold conditions vaporizer 93C can be pre-heated
electrically to provide enough vapor to start the engine but this
is not usually required. Once the engine starts, vaporizer 93C can
be heated by passing hot exhaust gas through the heating jacket
formed by housing 95C or, alternatively, by engine coolant.
As additional volatile liquid fuel is supplied to second vaporizer
93C from tank 97B, the liquid level in tank 97B drops. At a
predetermined level, switch 90C signals pump 90A to start
operating. Pump 90A pumps fuel vapor from first vaporizer 98 and
compresses it in condenser tube 91A wherein it cools and condenses
and is forced through regulating valve 96B into tank 97B.
Alternatively, valve 96B can be a one-way check valve. As vapor is
pumped from first vaporizer 98, the pressure therein drops and
gasoline from tank 90 is drawn in by vacuum at a metered rate
through conduit 96 and regulating valve 97. Regulating valve 97 is
set to maintain enough vacuum in vaporizer 98 to vaporize the light
ends of the gasoline. In this embodiment, only the most volatile
components are removed from gasoline such as the propane, butanes
and pentanes. Pressure within vaporizer 98 can be maintained from
about 1-14 psia, preferably from about 10-14 psia, to accomplish
this depending on the temperature in the vaporizer. In the
preferred embodiment shown the temperature within the vaporizer is
maintained at an elevated level by circulating thermostatically
controlled coolant through jacket 92B. Additionally, the amount of
coolant may be varied to provide a constant temperature (e.g.,
100.degree.-150.degree.F.) in the volatile-depleted fuel that
collects at the bottom of vaporizer 98. By controlling vacuum and
temperature in the first vaporizer, a narrow range of volatiles can
be removed. Since these volatiles are again to be vaporized after
condensation, it is preferable to minimize the amount of higher
boiling material carried with them since this material is more
difficult to vaporize in second vaporizer 93C. As an aid in this
some distillation packing can be provided in conduit 99 upstream
from pump 90A. Alternatively, some standard distillation structure
can be incorportated in conduit 99 such as a number of bubble cap
plates.
In this embodiment a useful range of volatiles removed from the
gasoline and condensed as a source of volatile fuel are those
boiling up to about 150.degree.F. and, more preferably, up to about
120.degree.F. (ASTM D-86).
The volatile-depleted fuel that collects in the bottom of first
vaporizer 98 is pumped by pump 96D to tank 99D and used
preferentially at normal operating temperature in the same manner
as in the FIG. 8 embodiment.
Once the engine attains a temperature at which it could operate
normally without choking, the thermoswitches on the engine signal
concurrently valves 94E and 95E to open and valve 95D to close,
thus supplying liquid fuel to the engine through conduit 91, valve
92, and fuel pump 93. As in the FIG. 8 embodiment, once the engine
attains full operating temperature, valve 91E is signaled to open
if liquid level switch 90E indicates adequate volatile-depleted
fuel. Valve 92 may be fully or partially closed at this time to
assure preferential use of the volatile-depleted fuel while the
engine is hot.
By the practice of the above-described invention, the exhaust
hydrocarbon and carbon monoxide emission is substantially reduced.
This reduction is obtained while supplying the vehicle with normal
gasoline without the necessity of supplying two separate fuels to
the vehicle.
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