U.S. patent number 3,789,820 [Application Number 05/190,550] was granted by the patent office on 1974-02-05 for compressed gaseous fuel system.
This patent grant is currently assigned to Victor Equipment Company. Invention is credited to Lloyd A. Douglas, Kirk T. Garanflo.
United States Patent |
3,789,820 |
Douglas , et al. |
February 5, 1974 |
COMPRESSED GASEOUS FUEL SYSTEM
Abstract
Apparatus for enabling a conventional vehicle to be operated on
a compressed gaseous fuel, characterized by a high degree of safety
with features such as concentrating the high pressure portion of
the apparatus into a section that is located outside of the
passenger compartment for safety; employing a remote indicating
fuel gauge that does not have a fuel connection inside the
passenger compartment; employing double regulators with respective
relief valves vented to a safe area; employing special
factory-tested high pressure assemblies, and employing an excess
flow shut-off valve for blocking flow in the event of a line
failure. Also disclosed are specific embodiments such as employing
a single stage compensated high pressure regulator for uniform
performance until the container of compressed gaseous fuel is
substantially empty; and parallel connected containers for
increased range.
Inventors: |
Douglas; Lloyd A. (Fort Worth,
TX), Garanflo; Kirk T. (Fort Worth, TX) |
Assignee: |
Victor Equipment Company
(Denton, TX)
|
Family
ID: |
22701802 |
Appl.
No.: |
05/190,550 |
Filed: |
October 19, 1971 |
Current U.S.
Class: |
123/27GE; 123/1A;
123/526; 123/576 |
Current CPC
Class: |
F02M
21/0239 (20130101); F02D 19/022 (20130101); F02M
21/029 (20130101); F02M 21/0242 (20130101); F02M
21/0224 (20130101); Y02T 10/32 (20130101); Y02T
10/30 (20130101) |
Current International
Class: |
F02M
21/02 (20060101); F02m 013/06 (); F02m
013/68 () |
Field of
Search: |
;123/121,27GE,1A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Assistant Examiner: Cox; Ronald B.
Attorney, Agent or Firm: Fails; James C. Wofford, Felsman
& Fails
Claims
1. In apparatus for enabling a vehicle engine normally employing a
conventional fuel to operate on a second fuel, and normally
including:
a fuel-air mixer connected with the intake manifold of said engine
and with a low pressure regulator and having means for admixing a
combustion supporting gas with said second fuel;
on-off valve interposed in a conduit means for carrying said second
fuel to said vehicle engine; said conduit means being connected
with said fuel-air mixer and with a pressure regulator;
low pressure regulator interposed in said conduit means downstream
of said on-off valve for reducing upstream pressure to a low
pressure in the range of from a few inches of water to a few pounds
per square inch guage (psig) for supplying to said fuel-air mixer;
and
on-off valve interposed in a fuel line supplying said conventional
fuel for stopping flow of said conventional fuel to said engine
when said second fuel is being employed; the improvement
comprising:
a. a high pressure section located outside of the passenger
compartment of said vehicle for safety, said high pressure section
including:
i. at least one container of a compressed gaseous fuel under
superatmospheric pressure; said compressed gaseous fuel serving as
said second fuel; said container being capable of withstanding
pressure in excess of 1,000 pounds per square inch gauge (psig);
and
ii. a high pressure assembly connected with said container of
compressed gaseous fuel; said high pressure assembly including a
first high pressure fitting for said container of said compressed
gaseous fuel; high pressure tubing connected to said first high
pressure fitting; a second high pressure fitting connected to said
tubing;
a fill connection connected with said second high pressure fitting
and into the remainder of said high pressure assembly for refilling
said container with said compressed gaseous fuel;
fuel gauge means connected responsively with said second high
pressure fitting and into the remainder of said high pressure
assembly for monitoring the quantity of said compressed gaseous
fuel in said container;
and high pressure regulator connected with said second high
pressure fitting and into the remainder of said high pressure
assembly for regulating a downstream pressure to a medium pressure
in the range of from several psig to 150 psig; and
b. medium pressure relief valve connected with the downstream side
of said high pressure regulator for venting said gaseous fuel at
pressures greater than a preset maximum; said medium pressure
relief valve having means for altering said preset maximum; and
2. The apparatus of claim 1 wherein said high pressure regulator
comprises
3. The apparatus of claim 1 wherein said high pressure assembly
is
4. The apparatus of claim 1 wherein said fill connection includes a
convenient, sealing connect-disconnect fitting and has check valve
means disposed on both sides of the joint of said fill connection,
said check valve means being operable to permit flow when said
fitting is connected for filling said container and operable to
prevent flow from either of the
5. The apparatus of claim 1 wherein a low pressure relief valve is
connected with the downstream side of said low pressure regulator
for venting said gaseous fuel at pressures above a second preset
maximum low pressure; said low pressure relief valve having means
for altering said
6. The apparatus of claim 1 wherein said apparatus is installed in
an automobile, said high pressure section is installed in the trunk
of said automobile; and said medium pressure relief valve has a
vent pipe that traverses to the exterior of said trunk and to a
safe place for venting
7. The apparatus of claim 1 wherein an excess flow shut-off valve
is incorporated into said apparatus for blocking flow from said
high pressure assembly in the event there is a failure at some
point that would otherwise vent said gaseous fuel at a rate greater
than a predetermined
8. The apparatus of claim 1 wherein there are a plurality of
containers of said compressed gaseous fuel and said high pressure
assembly comprises a manifold interconnected with said plurality of
containers; said containers
9. The apparatus of claim 1 wherein said fill connection has check
valve means and a redundant check valve is interposed in the flow
line to
10. In apparatus for enabling a vehicle engine normally employing a
conventional fuel to operate on a second fuel, and normally
including:
a fuel-air mixer connected with the intake manifold of said engine
and with a low pressure regulator and having means for admixing a
combustion supporting gas with said second fuel;
on-off valve interposed in a conduit means for carrying said second
fuel to said vehicle engine; said conduit means being connected
with said fuel-air mixer and with a pressure regulator;
low pressure regulator interposed in said conduit means downstream
of said on-off valve for reducing upstream pressure to a low
pressure in the range of from a few inches of water to a few pounds
per square inch gauge (psig) for supplying to said fuel-air mixer;
and
on-off valve interposed in a fuel line supplying said conventional
fuel for stopping flow of said conventional fuel to said engine
when said second fuel is being employed; the improvement
comprising:
a. at least on container of a compressed gaseous fuel under
superatmospheric pressure; said container being capable of
withstanding pressure in excess of 1,000 pounds per square inch
gauge (psig); said compressed gaseous fuel serving as said second
fuel;
b. high pressure conduit and fittings connected with said container
of gaseous fuel;
c. a fill connection connected with said high pressure conduit and
fittings for refilling said container with gaseous fuel;
d. high pressure regulator for regulating a downstream pressure to
a medium pressure in the range of from several psig to 150 psig;
said high pressure regulator being connected at its upstream side
with said high pressure conduit and fittings;
e. medium pressure relief valve connected with the downstream side
of said high pressure regulator and said conduit means for venting
said gaseous fuel at pressures greater than a preset maximum; said
medium pressure relief valve having means for altering said preset
maximum;
f. a gas-air mixer serving as said fuel-air mixer; and
g. fuel gauge means including:
i. a pressure responsive element in fluid communication with said
container for monitoring pressure therein, said pressure responsive
element being disposed adjacent said container and outside the
passenger compatment of the vehicle; said pressure responsive
element being a pressure gauge that displays the pressure adjacent
said container also, facilitating monitoring during filling;
ii. transducing means for converting said pressure into a
single-valued transmissible signal;
iii. remote indicator gauge means disposed in said passenger
compartment and connected with said transducer means for effecting
a visual display of
11. The apparatus of claim 10 wherein said pressure gauge has a
pointer and said transducing means comprises a magnet that is
carried by said pointer, a potentiometer that is disposed above
said magnet; said potentiometer having as its potentiometer wiper
an electrically conductive magnetic follower that is connected with
a source of power, that is mounted for movement along substantially
the same path as said pointer and freely mounted so as to follow
the movement of said magnet on said pointer, and that effects a
voltage output that is a function of the position of the magnetic
follower on the potentiometer resistor; and said remote indicator
gauge means comprises a galvanometer that is responsive to said
voltage and is calibrated to read said voltage as a proportion of a
full container
12. The apparatus of claim 10 wherein said pressure gauge has a
pointer and said transducing means comprises a magnet that is
carried by said pointer, a circular potentiometer that is disposed
above said magnet; said circular potentiometer having as its
potentiometer wiper an electrically conductive magnetic follower
that is connected with a source of power, that is pivotally mounted
for pivotal movement about substantially the same axis as said
pointer and freely mounted so as to follow rotational movement of
said magnet on said pointer, and that effects a voltage output that
is a function of the position of the magnetic follower on the
potentiometer resistor; and said remote indicator gauge means
comprises a galvanometer that is responsive to said voltage and is
calibrated to read said voltage as a proportion of a full container
of said gaseous fuel.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to apparatus for enabling a conventional
internal combustion engine to operate on a compressed gaseous fuel.
More particularly, this invention relates to apparatus for enabling
a vehicle employing an engine that is normally operated on a
conventional fuel to operate on a compressed gaseous fuel; and, in
specific embodiments, is directed at safety features that are
primarily useful where the vehicle has a passenger compartment,
even if only for the driver.
2. Description of the Prior Art
Internal combustion engines have been operated on conventional fuel
such as gasoline or diesel fuel for a relatively long time.
Moreover, the internal combustion engines have been converted to
operate on hydrocarbon fuels having shorter length molecules; such
as, liquified petroleum gases or propane. Additionally, internal
combustion engines have been operated at remote field locations on
low pressure natural gas or methane. Experience with these remote
engines indicates that the pollutant content of the exhaust gases
is much less when the engine is operated on natural gas than when
operated on the longer chain hydrocarbon molecules such as employed
in gasoline. With the advent of concern over polluting our
atmosphere, there has been increased interest in the use of short
hydrocarbon molecules as the fuel for the internal combustion
engine, since these molecules result in fewer contaminating free
radicals spewed in the atmosphere in the exhaust gases from the
engine.
For example, it has been found that an internal combustion engine
such as run in a pick-up truck has exhaust gases that are
remarkably free of the more objectionable pollutants; such as,
hydrocarbon free radicals and even the nitrogen containing
pollutants like the brown nitrous oxide which is a constituent of
the smog-type haze in the larger cities. The reason for the
observed low content of the pollutants is not exactly clear but the
low content makes desirable the use of compressed gaseous fuel such
as compressed natural gas, comprising the short hydrocarbon
molecules like methane.
One of the objectionable features of the prior art attempts to
employ methane was the absence of adequate safety features. This
was due primarily to the fact that the internal combustion engines
were operated in remote locations away from the more populous areas
in powering gas compressors or the like that did not have
passengers associated therewith. It is sociologically imperative
that any system, or apparatus, which would allow converting a
vehicle to operate on compressed gaseous fuel incorporate safety
factors to compensate for the increased hazards of which the
general public may not be fully aware.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view, partly schematic, illustrating
one embodiment of this invention employed on a conventional pick-up
truck.
FIG. 2 is a more detailed side elevational view, also partly
schematic, of the embodiment of FIG. 1.
FIG. 3 is a graph of the flow rate versus pressure to illustrate
desirable performance characteristics of an embodiment of this
invention.
FIG. 4 is a front elevational view of a fuel gauge means for
monitoring the quantity of the fuel in accordance with one
embodiment of this invention.
FIG. 5 is a side elevational view, partly cut away, illustrating
elements of the embodiment of FIG. 4.
FIG. 6 is a schematic diagram illustrating the remote fuel
indicator in accordance with an embodiment of this invention.
FIG. 7 is a side elevational view of a high pressure section
containing several cylinders of compressed gaseous fuel for
increased range, in accordance with another embodiment of this
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring to FIGS. 1 and 2, the apparatus 11 is illustrated
installed in a vehicle such as a pick-up truck 13 employing a
conventional engine 15. By conventional engine is meant an internal
combustion engine that runs on a conventional fuel such as
gasoline, diesel fuel, or the like. The apparatus 11 comprises the
major elements or subassemblies of at least one container 17, high
pressure assembly 19, including fill connection 21, fuel gauge
means 23 for monitoring the quantity of the compressed gaseous fuel
in the container 17, and high pressure regulator 25, medium
pressure relief valve 27, on-off valve 29, low pressure regulator
31, gas-air mixer 33, and on-off valve 35 for turning off
conventional fuel when the compressed gaseous fuel is being
employed. As illustrated, the container 17, the high pressure
assembly 19, the fill connection 21, the fuel gauge means 23, and
the high pressure regulator 25 are arranged in a high pressure
section 37 that is located rearwardly of the passenger comparatment
39 for safety. In FIGS. 1 and 2, the high pressure section 37 is
illustrated as being installed in the pick-up bed portion of a
pick-up truck 13. In an automobile, the high pressure section is
customarily located in the truck, outside of the passenger
compartment and out of sight.
There is at least one container 17; and, preferably, a plurality.
For example, as illustrated in FIG. 7, there may be seven or more
containers 17 for increased range of the vehicle. Any suitable high
pressure container that is designed to hold the desired pressure of
the compressed gaseous fuel may be employed. In a preferred form of
construction, methane cylinders are employed. The container may
hold, for example, compressed gaseous fuel up to 2,200 pounds per
square inch gauge (psig). For example, regulatory agencies such as
the Department of Transportation specify acceptable cylinder
pressures for respective vehicles.
The high pressure assembly 19 comprises high pressure fittings 40;
for example, fittings to match the CGA (Compressed Gas Association)
350 methane connection on the methane cylinders. The high pressure
assembly illustrated comprises a high pressure manifold including
respective conduit means such as tubing 41 which may be of
stainless steel; and fittings such as cross 43, FIG. 2, at least
the interior half of fill connection 21, check valve 47, fuel gauge
means 23, high pressure regulator 25, high flow shut-off valve 87,
on-off valve 29, and the respective adapter fittings 48 for
connecting the tubing 41 to the container-matching fittings 40.
Because of the need for safety, the high pressure assembly 19 is
preferably factory assembled and tested for leaks before it is
released to be sold or used.
The fill connection 21 is connected into the high pressure assembly
19 for refilling the container 17 with the gaseous fuel. The fill
connection 21 may comprise any convenient, sealing,
connect-disconnect fitting. For additional safety, at least check
valve means are disposed on both sides of the connect-disconnect
fitting. The check valve means are operable to permit flow into the
high pressure assembly when the connect-disconnect fitting is
connected; and to prevent flow from the free ends of the
connect-disconnect fitting when disconnected. For example, a
conventional quick-connect fitting having respective bayonet and
receiving connector portions may be employed. In the conventional
quick-connect fitting, the check valves therein may be moved to the
open position when the bayonet is inserted into the receiving
connector portion for connection; but are moved to the closed
position when the bayonet is removed so as to prevent flow from the
disconnected ends, as might occur when the connection is broken;
thereby reducing fire hazard and the like. A check valve 47, FIGS.
2 and 7, is also provided to permit flow in one direction, as
indicated by the arrow 53 so as to enable filling the containers,
but to prevent flow in the opposite direction. This check valve 47
is includes to prevent reverse flow when the quick-connect halves
are coupled and a second vehicle at lower tank pressure is
connected to a fill system; this prevents partial emptying of the
first vehicle. If desired, a single valve such as valve 55, FIG. 7,
may be provided to prevent flow outwardly from the manifold of the
high pressure assembly, or, as illustrated in FIG. 2, the
respective valves 57 on each respective cylinder may be employed to
control the flow from the cylinders.
The fuel gauge means 23 is screwed into cross 43 and includes a
pressure responsive element such as bourdon tube 51, FIGS. 5 and 6,
in fluid connection with the container for monitoring the pressure
therein. Any high pressure gauge may be employed as fuel gauge
means 23 as long as it is commensurate with the range of pressure
employed in the containers 17. Preferably, the fuel gauge means 23
includes, also, a remote indicating gauge 59, FIG. 6, that may be
emplaced in the passenger compartment to read the quantity of fuel.
For safety, no line containing the gaseous fuel should be run into
the passenger compartment, so the remote indicating gauge 59 must
operate without directly sensing the pressure. It has been
recognized that the running of lines with the combustible gaseous
fuel into the passenger compartment is undesirable, particularly
where the fuel is at super atmospheric pressure. Several states
have enacted statutes prohibiting employing any direct reading
pressure gauges, with the attendant pressurized fuel lines, in the
passenger compartment. As illustrated in FIGS. 1, 2 and 6, the
pressure responsive element such as the bourdon tube 51 in the fuel
gauge means 23 is disposed adjacent the container 17 and outside
the passenger compartment. Preferably, the gauge encompassing the
bourdon tube 51 will also have a direct reading dial and pointer
thereon to facilitate monitoring the amount of fuel and the
quantity that is filled when fuel is added via the fill connection
21, without requiring continually adverting to the remote fuel
indicator 59 in the passenger compartment. In the preferred form in
which the remote indicating fuel gauge 59 is employed, a
transducing means 61 is employed for converting the pressure into a
continuous, single-valued transmissible signal which the remote
indicating fuel gauge 59 can use to effect a visual display of the
quantity of the fuel in response to the signal. As illustrated, the
transducing means 61 comprises a magnet 63 that is carried by a
pointer 65, FIGS. 4 and 5; a potentiometer 67; and a power source
such as battery 69 that is electrically connected serially with the
potentiometer 67. As illustrated, the potentiometer 67 is a
circular potentiometer. The circular potentiometer 67 is disposed
above the magnet 63 and has a potentiometer wiper 71 that is
magnetically coupled with the magnet 63 carried by pointer 65.
Consequently, the potentiometer wiper 71 will follow the pointer
65. The potentiometer wiper 71 is electrically conductive and has a
brush that wipes along the circular resistor 73 of the circular
potentiometer 67. As the potentiometer wiper 71 assumes a
predetermined position, a unique voltage output is effected.
Expressed otherwise, the voltage output is a function of the
position of potentiometer wiper 71 on the potentiometer resistor
73. The remote indicating fuel gauge 59 comprises a galvanometer
type instrument such as a voltmeter that is responsive to the
voltage and is calibrated to read the voltage as a proportion of a
full container of the gaseous fuel.
The high pressure regulator 25 is connected into the high pressure
assembly 19 and directly with the valve 57 of cylinder 17, FIG. 2,
for regulating a dowstream pressure; such as, through on-off valve
29; to a medium pressure. Preferably, the high pressure regulator
25 is a single stage compensated regulator for uniform performance
until the container 17 is substantially empty, as illustrated in
FIG. 3. Therein, the flow rate, in standard cubic feet per hour
(scfh); and, consequently, engine performance; is a flat curve 75
regardless of the pressure of the gaseous fuel in the container 17,
FIG. 2, until the container 17 gets below the differential pressure
necessary for proper flow of fuel and operation of the low pressure
regulator 31. This low pressure denotes a substantially empty
container 17. Better maximum speed results from such flat curves. A
desirable single stage compensated regulator is described and
claimed in copending application Ser. No. 827,711, entitled "Single
Stage, Compensated Pressure Regulator," inventor Ray R. Zimmer,
filed May 26, 1969, assigned to the assignee of this invention. The
medium pressure may range from several psi to as high as 150
psi.
The medium pressure relief vlave 27 is connected with the
downstream side of the high pressure regulator 25 for venting the
gaseous fuel at pressures greater than a preset maximum. The medium
pressure relief valve 27 has a means such as a covered screw (not
shown) for altering the preset maximum. Any conventional medium
pressure relief valve may be employed as long as its range of
preset maximum pressures is commensurate with the medium pressure
desired in the conduit means 77 conveying the gaseous fuel to the
engine 15. While the medium pressure relief valve 27 may be vented
directly to the atmosphere in an open pick-up bed, it is preferred
that it be vented, as via conduit means 79, to a safe place such as
at the rear of the vehicle. The conduit means 79 is shown in dashed
lines in FIG. 2. The conduit means 79 is necessary when the high
pressure section 37 is emplaced in the trunk of a vehicle, in order
to prevent the build up of explosive gases in the trunk in the
event of pressure relief.
The on-off valve 29 is interposed in the conduit means 77 for
preventing or permitting flow of the compressed gaseous fuel to the
engine 15. Preferably, the on-off valve 29 is a solenoid operated
on-off valve. Such on-off valves are conventional. Preferably also,
the on-off valve 29 is connected with the downstream side of the
high pressure regulator 25 so that it may have a relatively less
expensive low pressure body instead of requiring a body that is
structurally strong enough to withstand the high pressure of the
compressed gaseous fuel in the high pressure assembly 19. As
illustrated, the on-off valve 29 is a solenoid operated valve
having a solenoid 81 that is electrically connected with ground and
via conductor 83 with a switch 85 located inside of of the
passenger compartment 39. The switch 85 may comprise a three
position toggle switch effecting, in two of the positions,
respective on and off operation of the solenoid 81. Conventionally,
the switch 85 will be connected through a master switch such as the
ignition switch so that the operation of the switch 85 is not
necessary each time the engine is started or stopped.
The conduit means 77 effects a closed passageway for the
transmission of the gaseous fuel from the high pressure regulator
25 to the gas-air mixer 33 on the engine. The conduit means 77
necessarily incorporates the requisite conventional fittings for
connection with the elements interposed therein; for example, the
on-off valve 29; a high flow shut-off valve 87, if emplaced
therein; and the low pressure regulator 31. The conduit means 77
may comprise pressure tubing 89 and a flexible hose 91 for carrying
the respective medium and low pressures. For example, the tubing 89
may be nylon tubing reinforced with steel mesh and covered for
protection, or metallic tubing such as steel, copper or
aluminum.
The low pressure regulator 31 is interposed into the conduit means
77 downstream of the on-off valve 29. The low pressure regulator 31
reduces the medium pressure to a low pressure for feeding to the
gas-air mixer 33. The low pressure may range from a few inches of
water to a few psi, depending upon the type of gas-air mixer 33
employed.
To add an additional safety feature, we have resorted to a low
pressure relief valve that is connected with the downstream side of
the low pressure regulator to vent the gaseous fuel in the event
the low pressure becomes greater than a second preset maximum. This
protects the gas-air mixer 33 as well as other low pressure
components of the system. We employ a low pressure relief valve
that is connected into the body of the low pressure regulator 31.
Such low pressure relief valves are conventional and need not be
described in detail herein.
The gas-air mixer 33 is connected; for example, via a conventional
carburetor 93; with the intake manifold of the engine 15, and with
the hose 91. The gas-air mixer 33 has means for admixing a
combustion supporting gas such as air with the gaseous fuel. Any of
the conventional gas-air mixers may be employed. We have found the
gas-air mixer supplied commercially by Impco to be
satisfactory.
The on-off valve means 35 is interposed in a line supplying the
conventional fuel for stopping the flow of the conventional fuel to
the engine when the gaseous fuel is being employed. Preferably, the
on-off valve means 35 comprises a solenoid operated on-off valve
having solenoid 95 for effecting the on-off operation. The solenoid
95 is connected with ground and via conductor 97 with fuel control
switch 85. The solenoid 95 operates conversely to solenoid 81 such
that the flow of conventional fuel is stopped when the flow of the
gaseous fuel is started or the flow of conventional fuel is started
when the flow of gaseous fuel is stopped. Any of the conventionally
operable solenoid-operated valves may be employed. The pressure
that the body of the valve is designed to withstand will be
determined by the type of fuel being employed. Ordinarily, where
gasoline and diesel fuel are being employed, a low pressure body is
adequate to withstand the pressure of the conventional fuel
pump.
We have found it advantageous from a safety standpoint to provide
an excess flow shut-off valve, such as high flow valve 87 for
blocking the flow in the event there is a failure at some point in
the flow path of the compressed gaseous fuel. For example, if
tubing 89 were ruptured, the excess flow valve 87 would close and
prevent the flow of the gaseous fuel which would otherwise result.
The excess flow valves are conventional and are commercially
available. Ordinarily, they comprise a check valve means such as a
ball or poppet that is held in a predetermined position, as by
suitable biasing means, but which is operated into a shut position
against a seat to stop the flow as long as the rate of flow tends
to be above a predetermined maximum. The predetermined maximum is
responsive to pressure differential. The high flow shut-off valve
87 is located downstream of the high pressure regulator 25 for
constant inlet pressure. Since the details of the excess flow
shut-off valve are not being claimed, per se, and are commercially
available, there is no need to supply the well-known details
thereof.
In operation, the mechanical and electrical elements are installed
to effect the system described hereinbefore and illustrated in the
figures. The containers 17 are filled with the compressed natural
gas to the desired pressure; for example, 2,200 psig. The high
pressure connections are checked to ensure there are no leaks. The
fuel control switch 85 is set for the conventional fuel; for
example, the gasoline position; and the engine is started. Then,
the lines and connections are checked for leaks at the on-off valve
means 35. The engine is converted to run on gaseous fuel by
positioning the fuel control switch 85 in another position and the
engine started and the connections checked for any compressed
gaseous fuel leaks. Smooth running of the engine on gaseous fuel is
accomplished by adjusting the lean-rich adjusting screw of the
gas-air mixer 33 to obtain a smooth idle. On the other hand, if the
supply of compressed gaseous fuel becomes low, or it is desirable
to run the engine on the conventional fuel for other reasons, the
fuel control switch 85 is operated to the opposite position and
transistion to the conventional fuel is smoothly made. If desired,
the low pressure regulator may be preset to maintain from five to
ten inches of water pressure on the compressed gaseous fuel. If
natural gas is to be the only fuel used, the engine ignition timing
may be set to 7.degree. to 10.degree. more advanced than the
manufacturer's recommendations for the conventional fuel. For
increased economy and performance, if natural gas is to be the
prime fuel the spark plug gap setting should be decreased to half
of the normal gap setting. The engine timing is set at the maximum
recommended by the vehicle manufacturer if satisfactory operation
is desired on both fuels.
The compressed gaseous fuel should be dried to have a dew point of
at last -65.degree. Fahrenheit at 2,250 psig, because, otherwise,
the large pressure drop between a filled container 17 and the
medium pressure conduit means 77 lowers the temperature
sufficiently to cause operational difficulties.
The materials of construction ordinarily employed in this art are
adequate for use herein and no new exotic materials need be
employed.
Although the invention has been described with a certain degree of
particularity, it is understood that the present disclosure has
been made only by way of example and that numerous changes in the
details of construction and the combination and arrangement of
parts may be resorted to without departing from the spirit and the
scope of the invention.
* * * * *