US3593694A

US3593694A - Fuel-cooling system

Info

Publication number: US3593694A
Application number: US821913A
Authority: US
Inventors: Stuart G Hilborn
Original assignee: Fuel Injection Engineering Co
Current assignee: Fuel Injection Engineering Co
Priority date: 1969-05-05
Filing date: 1969-05-05
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20

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.

Description

United States Patent Inventor Stuart (1. Hilborn 2,635,597 4/1953 123/119 South Laguna.Calil. 2,869.527 1/1959 123/119 AppltNo. 821,913 3.l18,492 1/1964 123/136X Filed May 5,1969 3.187.732 6/1965 123/119 Patented July 20,1971 1 3,314,665 4/1967 123/136 X Assignee Fuel Injection Engineering Company 3,473,523 10/1969 Hilborn 123/1 19 X Smnh Laguna Primary Erunu'ner- Laurence M. Goodridge Attorney-Smyth. Roston & Pavitt FUEL-CO0L1NG SYSTEM 24 Claims, 3 Drawing Figs.

US. Cl 123/119 R, ABSTRACT; This disdosure d -ib a f |i System 23/139, 123/139 261/160, 1213/4131 forcooling the liquid fuel in the system to avoid vapor lock. Int. Cl F02d 3/04 According to h ifi embodiment disdosei a f l injec Field of Search 123/1 19, {ion nozzle injects f into an intake tube which is connected 32; 261/190 to an intake manifold. The fuel so injected vaporizes. A fuel- References Cited cooling jacket surrounds the intake tube and liquid fuel is passed therethrough. The liquid fuel passing through the cool- UNITED STATES PATENTS ing jacket is cooled by the latent heat of vaporization from the 1,953,809 4/1934 Kenneweg 261/160 vaporized fuel within the intake tube FUEL-COOLING SYSTEM 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 in stallation 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. ln 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 fuelcooling 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 fuelcooling system. The present invention minimizes the forma' tion of these vapors through the provision ofa 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. I

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 tanlc supplying only the ad ditional 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 inventiqn, the secondary fuel tank lies downstream of the fuelcooling 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. [n 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 inaccordance 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 ofa 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 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 US. 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. lmpingement 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 6] 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 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 870 with the outlet 87a being illustrated 180 from its true position. A tube 89 interconnects the outlet 87 of the cooling jacket 23 with the inlet 85a of the cooling jacket 230. 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 vaporiz' ing 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 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 fuelcooling 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 ofa 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 ofa 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 I79 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 1840, 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 preselectedfuel 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 US. 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 16] 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.

lclaim:

l. 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 coolingjacket.

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, respective ly, 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 com duits 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, eachof 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 fuelcooling 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-coolingjacket 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 fuelcoolingjackets.

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 fuelcooling 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.

ll. 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.

l2. 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 ll 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 I] wherein said secondary fuel tank is downstream of said fuel-cooling means.

15. A fuel injection system as defined in claim I] 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 fiow 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;

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 sup plied 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 fuelcooling 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 supply ing 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 noule 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.

Claims

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.

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.

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.

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.