U.S. patent number 3,593,694 [Application Number 04/821,913] was granted by the patent office on 1971-07-20 for fuel-cooling system.
This patent grant is currently assigned to Fuel Injection Engineering Company. Invention is credited to Stuart G. Hilborn.
United States Patent |
3,593,694 |
Hilborn |
July 20, 1971 |
FUEL-COOLING SYSTEM
Abstract
This disclosure describes a fuel-cooling system for cooling the
liquid fuel in the system to avoid vapor lock. According to the
specific embodiment disclosed, a fuel injection nozzle injects fuel
into an intake tube which is connected to an intake manifold. The
fuel so injected vaporizes. A fuel-cooling jacket surrounds the
intake tube and liquid fuel is passed therethrough. The liquid fuel
passing through the cooling jacket is cooled by the latent heat of
vaporization from the vaporized fuel within the intake tube.
Inventors: |
Hilborn; Stuart G. (South
Laguna, CA) |
Assignee: |
Fuel Injection Engineering
Company (South Laguna, CA)
|
Family
ID: |
25234592 |
Appl.
No.: |
04/821,913 |
Filed: |
May 5, 1969 |
Current U.S.
Class: |
123/39; 123/541;
123/41.31; 261/160 |
Current CPC
Class: |
F02M
37/20 (20130101); F02M 53/00 (20130101) |
Current International
Class: |
F02M
37/20 (20060101); F02M 53/00 (20060101); F02d
003/04 () |
Field of
Search: |
;123/119,136,32
;261/160 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Claims
I claim:
1. A fuel injection system for supplying fuel from a fuel source to
an intake manifold of an engine comprising:
an intake tube forming an extension of the intake manifold for
supplying air to the intake manifold;
first and second fuel injection nozzles mounted, respectively, on
the intake manifold and the intake tube;
conduit means for connecting said first and second fuel injection
nozzles to the fuel source;
pump means for supplying fuel through said conduit means to said
nozzles to cause the nozzles to inject fuel into the intake
manifold and the intake tube, respectively, whereby the fuel
injected into said intake tube vaporizes, the fuel injected by said
nozzles constituting a primary fuel supply, said pump means
supplying fuel to said first nozzle at various engine operating
conditions including nonidling conditions; and
means defining a fuel-cooling jacket extending at least part way
around said intake tube, at least a substantial portion of said
cooling jacket lying downstream of said second nozzle, said cooling
jacket forming a portion of said conduit means so that at least
some of the fuel from the fuel source including at least a
substantial portion of said primary fuel supply can flow
therethrough in heat exchange relationship with the fuel in said
intake tube whereby the latent heat of vaporization from the fuel
in said intake tube cools said portion of the primary fuel supply
as it flows through said cooling jacket.
2. A fuel injection system as defined in claim 1 wherein said
fuel-cooling jacket has an inlet for receiving fuel from the fuel
source and an outlet, said fuel-cooling jacket having first and
second end portions, said inlet and said outlet being located
closely adjacent said first and second end portions, respectively,
whereby the fuel must flow substantially completely through said
cooling jacket in traveling from said inlet to said outlet.
3. A fuel injection system as defined in claim 1 including coupling
means for connecting said intake tube to said intake manifold, said
coupling means providing a heat-insulating barrier to minimize heat
transfer between the intake manifold and the intake tube.
4. A fuel injection system as defined in claim 3 wherein said
fuel-cooling jacket completely surrounds said intake tube and said
second fuel injection nozzle is mounted at the end thereof remote
from said intake manifold, said fuel-cooling jacket having an inlet
and an outlet located at opposite ends of said fuel-cooling jacket,
and said fuel-cooling jacket being surrounded by an insulating
jacket constructed of heat-insulating material.
5. A fuel injection system as defined in claim 1 wherein said
intake tube includes a ram tube.
6. A fuel injection system as defined in claim 1 including a
supercharger and means for connecting the intake tube to the
supercharger.
7. A fuel-cooling system for use in a fuel system for supplying
fuel to an engine, said fuel-cooling system comprising:
first and second conduits for supplying air to first and second
cylinders of the engine;
first and second fuel injection nozzles mounted, respectively, on
said first and second conduits to inject fuel into said conduits,
the fuel injected by said fuel injection nozzles into said conduits
vaporizing to cool the air in the conduits and the conduits;
first and second fuel-cooling jackets surrounding said first and
second conduits, respectively, at least a substantial portion of
each of said fuel-cooling jackets lying downstream of its
respective fuel injection nozzle, each of said fuel-cooling jackets
having upstream and downstream end portions with the downstream end
portion being downstream of the associated fuel injection
nozzle;
said first fuel-cooling jacket having an inlet closely adjacent one
end portion thereof and an outlet closely adjacent the other end
portion thereof, said inlet being connectable to the fuel system to
receive fuel therefrom;
said second fuel-cooling jacket having an inlet closely adjacent
one end portion thereof and an outlet closely adjacent said other
end portion thereof; and
conduit means extending between said outlet of said first
fuel-cooling jacket and said inlet of said second fuel-cooling
jacket for providing a fuel passage between said fuel-cooling
jackets whereby the fuel supplied to said inlet is cooled by the
vaporization of fuel in the conduits and the fuel is required to
flow substantially completely through the full length of each of
said first and second fuel-cooling jackets.
8. A fuel-cooling system as defined in claim 7 wherein said other
end portion of said first fuel-cooling jacket is said upstream end
portion and said one end portion of said second fuel-cooling jacket
is said downstream end portion thereof.
9. A fuel-cooling system as defined in claim 7 including a
heat-insulating jacket surrounding at least one of said
fuel-cooling jackets.
10. A fuel-cooling system as defined in claim 7 wherein said first
conduit includes an intake tube, said intake tube being connectable
to an intake manifold of the engine, said fuel-cooling system
including coupling means for connecting said intake tube to the
intake manifold, said coupling providing a heat-insulating barrier
between said intake tube and the intake manifold to thereby
minimize heat transfer from the intake manifold to the intake
tube.
11. A fuel injection system for conducting fuel from a fuel source
to an engine comprising:
means for directing fuel into the engine;
conduit means for conducting fuel from the fuel source to said
means for directing;
means for supplying the fuel from the fuel source through said
conduit means to the engine;
fuel-cooling means downstream of the fuel source and upstream of
said means for directing for cooling at least some of the fuel
supplied by said means for supplying;
said means for supplying including a fuel injection pump downstream
of said fuel-cooling means;
a secondary fuel tank upstream of said fuel injection pump; and
bypass means downstream of said fuel-cooling means for bypassing at
least some of any excess fuel pumped by said fuel injection pump
into said secondary fuel tank while the engine runs, said fuel
injection pump pumping the fuel from the secondary fuel tank to
said means for directing.
12. A fuel injection system as defined in claim 11 including means
for limiting the maximum quantity of fuel which can be contained in
the secondary fuel tank to an amount less than the amount which is
containable at said source.
13. A fuel injection system as defined in claim 11 including means
upstream of said fuel injection pump for separating any vapors in
the fuel supplied thereto.
14. A fuel injection system as defined in claim 11 wherein said
secondary fuel tank is downstream of said fuel-cooling means.
15. A fuel injection system as defined in claim 11 wherein the
bottom of said secondary fuel tank is at an elevation above said
fuel injection pump whereby the fuel injection pump is kept well
primed.
16. A fuel injection system for an engine having a plurality of
cylinders comprising:
a main fuel tank adapted to contain fuel for operating the
engine;
a plurality of intake conduits mounted on said engine for supplying
air thereto, one of said intake conduits being provided for each of
said cylinders of the engine;
means for directing fuel into each of said intake conduits, the
fuel in each of said intake conduits vaporizing;
a plurality of heat exchangers mounted, respectively, in exchange
relationship with at least some of said intake conduits;
a secondary fuel tank adapted to contain fuel, said secondary fuel
tank being capable of containing less fuel than said main fuel
tank;
means for supplying fuel from said main fuel tank through at least
one of said heat exchangers to said secondary fuel tank, the heat
of vaporization of the vaporized fuel in the intake conduit cooling
the fuel in said one heat exchanger;
a fuel pump for pumping fuel from said secondary fuel tank to said
means for directing, said fuel pump being downstream of said
secondary fuel tank;
bypass means on the discharge side of said fuel pump for directing
excess fuel through at least another of said heat exchangers to
cool such excess fuel; and
means for returning at least some of the excess fuel from said
another heat exchanger to the secondary fuel tank.
17. A fuel injection system as defined in claim 16 wherein said
means for directing includes a main nozzle and an auxiliary nozzle
for each of said intake conduits, said system including a metering
valve downstream of said pump for controlling fuel flow to said
nozzles.
18. A fuel injection system as defined in claim 16 wherein said
secondary fuel tank lies above said main fuel tank, said system
including a standpipe in said secondary fuel tank for limiting the
maximum amount of fuel that can be contained therein and for
initiating gravity flow of any fuel in excess of said maximum
amount back to said main fuel tank.
19. A fuel injection system as defined in claim 16 wherein said
secondary fuel tank is vented to provide for vapor separation of
any vapors in the fuel supplied thereto.
20. A fuel injection system for conducting fuel from a fuel source
to an engine comprising:
means for directing fuel into the engine;
conduit means for conducting fuel from the fuel source to said
means for directing;
means for supplying the fuel from the fuel source through said
conduit means to the engine, said means for supplying including a
fuel pump;
fuel-cooling means for cooling at least some of the fuel in said
conduit means; and
a secondary fuel tank for receiving at least some of the fuel
cooled by said fuel-cooling means when the engine is running, said
fuel pump being supplied with fuel from said secondary fuel
tank.
21. A fuel injection system for supplying fuel from a fuel source
to an engine comprising:
means for directing fuel into the engine;
fuel-cooling means upstream of said means for directing and
downstream of said fuel source for cooling the fuel supplied
thereto;
means for supplying fuel from said fuel source through said
fuel-cooling means to provide relatively cool fuel;
a secondary fuel tank;
a conduit for supplying the relatively cool fuel from the
fuel-cooling means to the secondary fuel tank when the engine is
running;
pump means for supplying the relatively cool fuel from said
secondary fuel tank to said means for directing; and
said secondary fuel tank including means for separating any vapors
which may exist in the fuel supplied thereto whereby the pump means
receives relatively cool and relatively vapor free fuel.
22. A fuel injection system as defined in claim 21 wherein the fuel
pump is subject to pumping excess fuel and including means for
returning at least some of such excess fuel to the secondary fuel
tank without passing said some of such fuel through the fuel
source.
23. A fuel-cooling system for use in a fuel system for supplying
fuel to an intake manifold of an engine comprising:
a ram tube having an open end for supplying air from said open end
to the engine;
a coupling for mounting the ram tube on the intake manifold, said
coupling providing a heat-insulating barrier between said intake
manifold and the ram tube to reduce heat conduction from the intake
manifold to the ram tube and being constructed at least in part of
a heat insulating material to thereby further reduce heat
conduction from the intake manifold to the ram tube;
a heat exchanger in heat exchange relationship with said ram tube,
said heat exchanger being connectable to the fuel system so that
fuel from the system can pass therethrough; and
a fuel injection nozzle for supplying fuel to the ram tube at a
predetermined location therein, the fuel being vaporized in said
ram tube, the latent heat of vaporization of the vaporized fuel
cooling the ram tube, at least a portion of said heat exchanger
means being downstream of said fuel injection nozzle whereby the
fuel in said heat exchanger is cooled by the heat of vaporization
of the fuel in said ram tube.
24. A fuel cooling system as defined in claim 23 wherein said
coupling includes a band of heat-insulating material surrounding
the adjacent end portions of the ram tube and the intake manifold,
said band being in engagement with said end portions, said coupling
including a circumferential flange of heat-insulating material
lying between the adjacent ends of the ram tube and the intake
manifold.
Description
BACKGROUND OF THE INVENTION
Under certain conditions the operation of an internal combustion
engine can become greatly impaired due to excessive temperatures in
the fuel system. Such excessive temperatures create gas bubbles in
the fuel which causes the familiar vapor lock condition.
The vapor lock problem is magnified by high ambient air
temperatures, poor cooling of the engine compartment, operation of
the engine at high altitude, poor design and installation of the
fuel system, and by using a fuel which contains low boiling point
fractions. High-performance engines such as racing engines are more
likely to develop vapor lock because they have a higher heat output
and they are generally installed in lightweight, close-fitting
vehicle bodies where good ventilation is difficult to obtain. In
addition, fuel injection systems which are generally used on
high-performance engines are more sensitive than carburetors to the
vapor lock condition.
SUMMARY OF THE INVENTION
The present invention solves the vapor lock problem through the
provision of a fuel-cooling system. Another advantage of the
present invention is that it results in a small gain in horsepower
particularly at higher r.p.m.'s where the fuel flow to the engine
is large. Although the fuel-cooling system of this invention can be
used with different types of fuel systems it is particularly
adapted for use with a fuel injection system.
In the typical fuel injection system, a fuel injection nozzle
injects fuel into the intake manifold downstream of the throttle
valve. The fuel is atomized before or upon injection, and the heat
within the intake manifold causes vaporization of the atomized
fuel. The present invention makes use of the latent heat of
vaporization of the injected fuel by passing at least some of the
liquid fuel in the system in heat exchange relation with the
vaporized fuel to cool the liquid fuel and thereby prevent vapor
lock.
An intake tube is connected to the intake manifold for conducting
air to the intake manifold. Contrary to the usual practice, the
present invention provides a fuel injection nozzle upstream of the
throttle valve and mounted on the intake tube. The heat exchanger
is preferably in the form of a fuel cooling jacket which surrounds
the intake tube. To take advantage of the heat of vaporization,
substantially all of the fuel-cooling jacket should be downstream
of the fuel injection nozzle on the intake tube.
Although coils may be used for the heat exchanger, it is preferred
to use a cooling jacket because the cooling jacket is of simpler
construction. To assure that the fuel will pass through the full
length of the fuel-cooling jacket, the inlet and outlet therefor
should be at opposite ends of the jacket. Each of the intake tubes
can have a fuel-cooling jacket, and the fuel can be passed from one
fuel-cooling jacket to another to thereby obtain a maximum amount
of cooling. Preferably, the inlet to the fuel-cooling jacket is
below the outlet so that the jacket will always be full of fuel.
This arrangement also causes the heat exchanger to be of the
counterflow type.
For best results, the fuel system should include a dual set of
nozzles for each cylinder with the second or lower nozzle being
downstream of the throttle valve. Although the lower nozzle for
each engine cylinder can be deleted, this will result in an engine
that runs poorly when idling, at low speeds, and at part throttle.
Alternatively, the throttle valve can be raised above the upper
nozzle, i.e., the nozzle adjacent the fuel-cooling jacket, and the
lower nozzle can be eliminated. However, this construction is
rather cumbersome, and accordingly, a dual set of nozzles is
preferred for each engine cylinder.
When the engine is operating, the intake manifold becomes very hot.
The present invention teaches that for optimum fuel cooling, the
heat exchanger should be insulated from the intake manifold.
Preferably this is accomplished by joining the intake tube to the
inlet manifold with a heat-insulating coupling. The coupling
provides a heat-insulating barrier between the intake tube and the
intake manifold to avoid direct heat conduction therebetween. By
using a resilient material for the coupling, heat insulation and
vibration damping can both be obtained. To further optimize
results, the fuel-cooling jacket should be covered with insulating
material to avoid a heat gain from the air surrounding the
fuel-cooling jacket.
The formation of some vapors in the liquid fuel in a fuel system is
inherent notwithstanding the provision of a fuel-cooling system.
The present invention minimizes the formation of these vapors
through the provision of a highly efficient fuel-cooling system.
However, to eliminate any of the inherently formed vapors in the
fuel stream, the present invention also provides means for
separating such vapors from the liquid fuel. Preferably such vapor
separation occurs after the fuel-cooling operation has at least
begun.
The fuel pump for most fuel injection systems will, at times,
supply more fuel than the engine can efficiently use. For this
reason, many fuel injection stems provide one or more bypasses for
bypassing the excess fuel supplied by the fuel injection pump. Such
excess fuel is normally bypassed back to the main fuel tank. The
fuel injection pump adds some heat to the fuel pumped thereby and
is the location at which gas bubbles are most likely to form in
amounts which may be troublesome. Accordingly, the fuel-cooling
operation and/or the vapor separation operation preferably occur at
a location in the fuel system which is upstream of the fuel
pump.
If the excess fuel supplied by the pump were returned to the main
fuel tank, the cooling effect thereof would be lost in the main
fuel tank as this tank would contain a large quantity of fuel in
relation to the cool bypassed fuel which would be supplied thereto.
To overcome the disadvantage accompanying the loss of the cooled
bypassed fuel, the present invention provides a secondary fuel tank
which receives the cool bypassed fuel. The secondary fuel tank is
smaller than the main fuel tank and preferably only contains cool
fuel so that substantially none of the cooling already obtained is
lost. Actually the secondary fuel tank may be large, if desired,
but the quantity of fuel which it is capable of holding should be
small in relation to the quantity of fuel which can be retained in
the main fuel tank. In this manner, the cooling effect obtained
from the cooling system can be concentrated on a relatively small
amount of fuel with the main fuel tank supplying only the
additional fuel as is necessary to keep the level of fuel in the
secondary fuel tank at the desired level.
As the fuel injection pump is the location at which vapor lock is
most likely to occur, the secondary fuel tank is preferably
upstream of the pump so that the latter can take advantage of the
cool fuel therein. In a preferred form of the invention, the
secondary fuel tank lies downstream of the fuel-cooling means and
upstream of the fuel injection pump with the fuel-cooling means
being as close to the pump as possible so that the fuel flowing to
the pump will be as cool as possible. The secondary fuel tank is
elevated above the pump intake to keep the pump well primed. In a
preferred form of the invention, fuel is supplied from the main
fuel tank through a first bank of heat exchangers to the secondary
fuel tank. The fuel injection pump supplies fuel from the secondary
fuel tank to the main injection nozzle. A bypass is located on the
discharge side of the fuel injection pump for bypassing fuel bank
to the secondary fuel tank through a second bank of heat
exchangers.
The advantages of the secondary fuel tank and vapor separation can
be most efficiently accomplished by merely venting of the secondary
fuel tank. In a preferred form of the invention, the maximum fuel
level in the secondary fuel tank is controlled by a standpipe into
which excess fuel can drain and flow by gravity back to the main
fuel tank.
The invention, both as to its organization and method of operation
together with further features and advantages thereof may best be
understood by reference to the following description taken in
connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary, partially diagrammatic side elevational
view partially in section of a fuel-cooling system constructed in
accordance with the teachings of this invention. The portion of
FIG. 1 which is shown in section is shown in radial cross
section.
FIG. 2 is a fragmentary elevational view of a second form of
fuel-cooling system.
FIG. 3 is diagrammatic view of a fuel injection system constructed
in accordance with the teachings of this invention.
DESCRIPTION OF THE EMBODIMENT
Referring to the drawing and in particular to FIG. 1, reference
numeral 11 designates a fuel-cooling system constructed in
accordance with the teachings of this invention. The system 11
includes an injector or intake manifold 13 connectable to an engine
(not shown), an intake tube in the form of a ram tube 15 connected
to the intake manifold by a coupling 17, a main fuel injection
nozzle 19, an auxiliary fuel injection nozzle 21, and a fuel
cooling jacket 23.
The intake manifold 13 has a wall 25 defining a passage 27
extending therethrough for the purpose of supplying fuel and air to
one cylinder of the engine. A throttle valve in the form of a
butterfly valve 29 is mounted within the passage 27 to control the
flow of fluid therethrough to the engine.
Although other constructions can be used, in the embodiment
illustrated, the wall 25 defines an auxiliary manifold passage 31
which leads from a location within the passage 27 upstream of the
butterfly valve 29 to the nozzle 19. Although other kinds of
nozzles can be used, in the embodiment illustrated, the main fuel
injection nozzle 19 is of the airgap type, such airgap type of
nozzle being fully described in applicant's copending application
Ser. No. 560,538 now U.S. Pat. No. 3,519,407. Generally, the airgap
nozzle 19 has a fuel inlet 33 which is connected to the fuel supply
system and a plurality of air inlets in the form of radially
extending ports 35 which communicate with the auxiliary injector
passage 31. As described in said copending application, air enters
the ports 35 and forms a tubular column around the fuel stream, and
the air and fuel stream are simultaneously directed against a
deflector surface 37 of the nozzle 19. As shown in FIG. 1 the
deflector surface 37 lies within the passage 27 downstream of the
butterfly valve 29. Impingement of the fuel against the deflector
surface 37 causes the fuel to atomize and to be directed downwardly
toward the discharge end of the passage 27. The nozzle 19 projects
through the auxiliary injector passage 31 and the wall 25 and is
mounted on the wall 25 by cooperating threads on the nozzle and the
wall and by a nut 38 which is threaded onto the nozzle and into
engagement with the outer surface of the manifold 13.
The intake manifold 13 has a tubular manifold extension 39 which
provides a coaxial continuation of the passage 27. Although the
extension 39 may be mounted on the manifold 13 in any suitable
manner, in the embodiment illustrated, nut and bolt fasteners 41
project through flanges 43 and 45, respectively, of the manifold 13
and the extension 39.
The ram tube 15 is tubular and has a wall 47 which defines a
generally cylindrical ram tube passage 49 which is coaxial with the
passage 27. The ram tube passage 49 has an inlet 51 and the wall 47
is flared outwardly adjacent the inlet 51 to increase the diameter
of the passage 49. The wall 47 is preferably constructed of a
material having high heat conductivity such as metal and to further
improve heat conductivity through the wall 47, the region thereof
adjacent the fuel-cooling jacket 23 should be of minimum thickness.
In operation air enters the inlet 51 of the ram tube 15 and passes
through the passage 49 toward the outlet 52 of the passage 49.
The ram tube 15 and the extension 39 have confronting ends 53 and
55, respectively, which are held in spaced confronting relationship
by the coupling 17. During the operation of the engine, the
manifold 13 and the extension 39 become very hot. By providing an
insulating barrier 56 between the confronting ends 53 and 55, heat
conduction to the ram tube 15 is substantially reduced.
The coupling 17 may be virtually any type which provides a
heat-insulating barrier between the injector extension 39 and the
ram tube 15. In the embodiment illustrated, the coupling 17
includes a heat-insulating member in the form of a resilient
cylindrical band 57 constructed of rubber and embracing the
portions of the ram tube 15 and the extension 39 adjacent the ends
53 and 55. The band 57 preferably has a circumferential flange 56
lying between and engaging ends 53 and 55 to form a heat-insulating
barrier. The band 57 preferably tightly grips the intake tube 15
and the extension 39. Although any heat-insulating material having
suitable connector qualities may be utilized, it is preferred to
construct the band 57 of rubber because it is a good insulator and
is sufficiently resilient to provide vibration damping.
The coupling 17 also includes an outer tightening band 59 which, in
the embodiment illustrated, is constructed of metal. The band 59
circumscribes the band 57 and has a pair of confronting flanges 61
through which a suitable fastener 63 such as a nut and bolt project
to permit drawing of the flanges 61 toward each other with
consequent circumferential tightening of the band 59. In this
fashion, the band 59 serves to tighten the band 57 about the end
portions of the ram tube 15 and the extension 39. The band 59 in
the embodiment illustrated is sufficiently resilient to permit
installing it about the band 57. The metal band 59 is held out of
engagement with the ram tube 15 and the extension 39 by the
insulating band 57.
The auxiliary injection nozzle 21 is mounted on the ram tube 15
adjacent the inlet thereof. The auxiliary nozzle 21 has a fuel
inlet 65 and a deflector surface 67 within the passage 49. The
auxiliary nozzle 21 in the embodiment illustrated is not of the
airgap type. The nozzle 21 projects through a threaded aperture 69
in the wall 47 and is threadedly secured therein. In addition, a
nut 71 is threaded on to the exterior of the nozzle 21 and into
engagement with a boss 73 to rigidly mount the nozzle 21 on to the
ram tube 15.
The auxiliary nozzle 21 receives fuel from the inlet 65 and directs
it as a stream against the deflector surface 67 which initiates
atomization of the fuel and directs the fuel downwardly (as shown
in FIG. 1) toward the outlet of the ram tube 15. As the fuel
travels through the ram tube 15 toward the outlet thereof, it
vaporizes thereby cooling the airstream within the passage 49. The
cool air within the passage 49 cools the wall 47 of the ram
tube.
The cooling jacket 23 in the embodiment illustrated includes an
outer cylindrical wall 75, an upper wall 77, a lower wall 79 and a
portion of the wall 47. A jacket 81 of insulating material
completely encases the wall 75, 77 and 79 to minimize heat transfer
therethrough.
The walls 75, 77, 79 and 47 define a tubular chamber 83 having an
inlet 85 and an outlet 87. The inlet 85 is preferably connected to
the fuel system at a location therein so that all the liquid fuel
pumped by the fuel pump will pass therethrough. The chamber 83
preferably has a minimum radial dimension to thereby increase the
ratio of cooling area to volume of fuel with consequent improvement
in the heat transfer characteristics between the liquid fuel in the
chamber 83 and the vaporized fuel within the passage 49. The
chamber 83 preferably lies downstream of the nozzle 21. Stated
differently, the most effective heat transfer will occur downstream
of the deflector 67 of the nozzle 21 although the chamber 83 may
project upstream thereof, if desired.
To assure that the liquid fuel will travel through a substantial
portion of the chamber 83, the inlet 85 and the outlet 87 are
preferably spaced substantially axially of the chamber 83. In the
embodiment illustrated, the inlet 85 is located at the downstream
end or lower end of the chamber 83 while the outlet 87 is located
at the upstream end or lower end of the chamber 83. The inlet 85
and the outlet 87 in the embodiment illustrated are spaced
180.degree. circumferentially to thereby further increase the
length of the flow path through the chamber 83.
In an engine, one of the ram tubes 51 is provided for each of the
cylinders. In the form shown in FIG. 1, the ram tube 51 is shown in
detail, it being understood that the other ram tubes and
cooperating components of the system are identical for each of the
remaining cylinders of the engine. Thus, the ram tube 51 lies
adjacent an identical ram tube 51a having a cooling jacket 23a
mounted thereon. The jacket 23a has an inlet 85a and an outlet 87 a
with the outlet 87a being illustrated 180.degree. from its true
position. A tube 89 interconnects the outlet 87 of the cooling
jacket 23 with the inlet 85a of the cooling jacket 23a. In this
fashion, the liquid fuel is first passed through the cooling jacket
23 and then passed in sequence through each of the other cooling
jackets beginning with the cooling jacket 23a.
In operation of the system shown in FIG. 1, fuel under most
operating conditions is supplied to the main nozzle 19 and the
auxiliary nozzle 21. The nozzles 19 and 21 inject the fuel supplied
thereto into the manifold 13 and the ram tube 15, respectively,
with the fuel injected into the ram tube vaporizing as it moves
from the nozzle 21 toward the outlet 52 of the ram tube. The fuel
from the two nozzles is supplied to the engine in a conventional
manner with some of the fuel and air from the ram tube 15 passing
through the auxiliary manifold passage 31 into the ports 35 of the
nozzle 19 for injection by the latter into the manifold 13. During
idle or part throttle, there may be no fuel supplied by the nozzle
21 to the ram tube 15; however, for most high-performance engines,
such as racing engines, this condition exists for only a small
portion of the time that the engine is operating.
The latent heat of vaporization from the vaporized fuel in the
passage 49 cools the air in this passage and the cool air in turn
cools the wall 47 of the ram tube. Simultaneously, liquid fuel is
supplied through the inlet 85 into the chamber 83. The cool wall 47
cools the liquid fuel flowing from the inlet 85 to the outlet 87 of
the cooling jacket 23. The liquid fuel is then conducted via the
tube 89 into the cooling jacket 23 of the adjacent ram tube 51a.
The fuel is passed progressively through the remaining fuel-cooling
jackets and may then reenter the fuel system at a suitable
location. After passing through all of the fuel-cooling jackets,
the fuel is at a sufficiently low temperature so as to prevent
vapor lock even under severe operating conditions.
FIG. 2 illustrates a fuel-cooling system 101 which is identical to
the fuel-cooling system 11 except that the former has an intake
tube in the form of a sleeve 103 in lieu of the ram tube 51. The
sleeve 103 is connected to a manifold 105 which is supplied with
air by a supercharger 107 through a conduit 109. Several of the
sleeves 103 are supplied with air from the manifold 105 and, if
desired, a second manifold may be provided to supply air to a
second set of the sleeves for a second group of engine cylinders.
The fuel-cooling system 101 has an auxiliary injection nozzle 111,
a fuel-cooling jacket 113, a coupling 115, an intake manifold 117,
an inlet 119 to the fuel-cooling jacket 113 and an outlet 121 as
well as all of the other components described hereinabove with
reference to FIG. 1.
The fuel-cooling system of this invention may be used with many
different kinds of fuel systems. However, it is particularly
adapted for use in a fuel injection system of the type shown in
FIG. 3.
FIG. 3 illustrates a fuel injection system 151 which includes a
relatively large main fuel tank 153 containing liquid fuel which is
supplied by a relatively small electric motor operated supply pump
155 through a conduit 157 to an engine 159. The engine 159 has four
fuel-cooling jackets 161 and four additional fuel-cooling jackets
163 with one of the fuel-cooling jackets being provided for each
cylinder of the engine. Although other kinds of fuel-cooling means
may be used, the fuel-cooling jackets 161 and 163 are preferably of
the type shown in detail in FIG. 1.
The fuel from the conduit 157 is passed in series through each of
the four fuel-cooling jackets 161 with the piping arrangement being
of the type shown in FIG. 1 to provide flow throughout the full
length of each of the fuel-cooling jackets 161. From the
fuel-cooling jackets 161, the fuel flows through a conduit 165 into
the upper end of a secondary fuel tank 167. The secondary fuel tank
is quite small relative to the main fuel tank and contains a vent
opening 169 at the upper end thereof through which vapors from the
fuel in the secondary fuel tank 167 can escape.
To control the maximum fuel level within the secondary fuel tank
167, a standpipe 171 is provided within the secondary fuel tank.
The standpipe 171 is a hollow tube having an open upper end through
which liquid fuel in the secondary fuel tank 167 can pass if the
fuel level rises above the upper end of the standpipe. Thus, the
maximum fuel level within the secondary fuel tank is controlled by
the height of the upper end of the standpipe 171.
The bottom of the secondary fuel tank 167 lies above the main fuel
tank 153. Accordingly, gravity flow of any excess fuel within the
secondary fuel tank can occur through a conduit 173 which connects
the lower end of the standpipe 171 with the upper end of the main
fuel tank 153. The bottom of the tank 167 also lies above the
intake of a fuel injection pump 175.
Fuel is drawn from the secondary fuel tank by the fuel injection
pump 175 and pumped through a metering valve 177 to the injection
nozzles 19 and 21 (FIG. 1). The injection pump 175 will, under most
operating conditions, pump more fuel than the engine 159 can
effectively utilize. For this reason, it is necessary in many fuel
injection systems to provide one or more bypasses for bypassing
such excess fuel back to the fuel tank. In the embodiment
illustrated, a primary bypass 179 and a secondary bypass 181 are
illustrated, it being understood that these bypasses are purely
exemplary and other types of bypasses may be utilized.
The primary bypass 179 is provided to permit the driver to manually
vary the amount of fuel bypassed therethrough depending upon the
type of fuel which is being burned and the desired fuel/air ratio.
To this end the primary bypass 179 includes a manual selector valve
183 and three orifices or jets 184a, 184b and 184c of different
sizes with the selector valve being manually operable to
selectively direct flow through any of the jets. Of course other
types of primary bypasses may be used.
The metering valve 177 is controlled in conventional fashion by a
linkage from the throttle, and the metering valve 177 may be of the
type which bypasses an increasing amount of fuel through the
secondary bypass 181 as the metering valve reduces the fuel flow to
the main injection nozzle. The secondary bypass 181 includes a
valve 185 which is preferably a spring-loaded check valve which
opens at a preselected fuel pressure to permit flow through the
secondary bypass 181.
The bypassed fuel from the primary bypass 179 and the secondary
bypass 181 is then passed through the fuel-cooling jackets 163 in
the manner described hereinabove with reference to FIG. 1. The
bypassed fuel then flows back to the secondary fuel tank 167.
The fuel passing through the metering valve 177 flows to the main
fuel injection nozzles through a conduit 187 or to the auxiliary
fuel injection nozzles through a conduit 189 and a valve 191. The
valve 191 is a spring-loaded check valve which opens at a
preselected fuel pressure to permit fuel flow to the auxiliary
nozzles.
By way of example, the fuel system of FIG. 3 may be similar to the
fuel injection system shown in applicant's copending application
Ser. No. 754,752 now U.S. Pat. No. 3,473,523. Specifically, the
metering valve 177, the pump 175, the primary bypass 179 and the
secondary bypass 181 may be identical to the corresponding
components of the system shown in said copending application.
In operation of the system 151 of FIG. 3, fuel is supplied from the
main fuel tank 153 through the fuel-cooling jackets 161 in which
the temperature of the fuel is reduced by the latent heat of
vaporization of the fuel in the intake tubes for such fuel-cooling
jackets. The cool liquid fuel is then passed through the conduit
165 into the secondary fuel tank 167 and any vapors within the
liquid fuel are allowed to escape through the vent opening 169.
Fuel is drawn from the secondary fuel tank 167 by the injection
pump 175 and fed to the injection nozzles as permitted by the
metering valve 177 with any excess fuel flowing through the
bypasses 179 and 181 to the fuel-cooling jackets 163 where such
excess fuel is cooled by the latent heat of vaporization of the
vaporized fuel in the corresponding intake tubes. Cooling of the
excess fuel in the fuel-cooling jackets 163 is desirable to
eliminate any heat gain which may have occurred in such fuel as a
result of its passing through the injection pump 175. The excess
fuel is returned to the secondary fuel tank and thus, only fuel
which has passed through at least one of the cooling jackets 161 or
163 is fed to the secondary fuel tank. In this manner only
relatively cool fuel is retained in the secondary fuel tank.
Although exemplary embodiments of the invention have been shown and
described, many changes, modifications, and substitutions may be
made by one having ordinary skill in the art without necessarily
departing from the spirit and scope of this invention.
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