|Publication number||US2968473 A|
|Publication date||Jan 17, 1961|
|Filing date||Mar 5, 1958|
|Priority date||Mar 5, 1958|
|Publication number||US 2968473 A, US 2968473A, US-A-2968473, US2968473 A, US2968473A|
|Inventors||Mick Stanley H|
|Original Assignee||Gen Motors Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (3), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 17, 1961 s. H. MICK PRESSURIZED FUEL INJECTION SYSTEM 2 Sheets-Sheet 1 Filed March 5, 1958 XMSTK. w 5Q my D Av Wm? i m Q Q ATTOPA/6Y Jan. 17, 1961 s. H. MICK PRESSURIZED FUEL INJECTION SYSTEM 2 Sheets-Sheet 2 Filed March 5, 1958 IN VENTOR. Sfanfe 71(77Ftk PRESSURIZED FUEL INJECTION SYSTEM Stanley H. Mick, St. Clair Shores, Mich, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Mar. s, 1958, Ser. No. 119,439
Claims. Cl. 261-23) The present invention relates to a mechanism for pressurizing a fuel system. More specifically, the present invention relates to a mechanism for pressurizing a fuel injection system utilizing an atmospheric nozzle of the type shown in copending application Serial No. 591,889, Dolza, filed June 18, 1956.
It is becoming increasingly necessary to provide pressurized fuel systems in order to avoid serious problems, such as vapor lock, which attend the use of higher volatility fuels. It has long been common knowledge that by pressurizing a fuel system, e.g. maintaining a closed system and pressurizing the fuel therein, it is possible to eliminate the tendency of the fuel to vaporize Within the system. Many such pressurized fuel systems are available.
Previous types of pressurized fuel systems generally employ pressure opening nozzles and are, therefore, inapplicable in the case of a fuel injection system utilizing a continuously open atmospheric type nozzle. More specifically, an atmospheric type nozzle is normally disposed in an intake passage such that it is exposed to variations in manifold depression. Unless provision was made therefor, such manifold depression would tend to disrupt or unduly influence the quantity of fuel supplied to the nozzle. To prevent this occurring an envelope of atmospheric air is provided at a point within the nozzle where the fuel stream is to be directed into the intake passage. In this way the effect of manifold vacuum is neutralized since the fuel stream is sprayed from the nozzle at all times at substantially atmospheric conditions.
The difficulties of pressurizing a system using such atmospheric nozzles becomes apparent when it is realized that if the fuel only is pressurized the nozzle fuel orifice sizes would have to be considerably reduced in size in order to maintain the desired air-fuel ratio. Since such fuel orifice size is already extremely small, e.g. .011", and represents a critical part of such system both from manufacturing and clogging viewpoint, it is apparent that further reduction in fuel orifice size would be most undesirable.
The present invention represents a unique and yet sim ple means of pressurizing such a fuel system without the necessity of changing the fuel orifice size from that presently in use. In the present device a common source of air under pressure is provided and the air therefrom utilized to pressurize the fuel and at the same time pressurize the reference air provided to the atmospheric nozzle. In this Way a previously non-pressurized fuel system may be readily adapted for pressurized operation by simply adding air pressurizing means in the manner taught by the present invention.
Other objects and advantages of the present invention are set forth in the description which follows.
In the drawings:
Figure 1 is a partially sectioned view of a fuel system embodying the subject invention; and
Figures 2 and 3 are enlarged detail views.
2,968,4Y3 Patented Jan. 17, 1961 While the present invention may be adapted for use with any fuel system employing an atmospheric nozzle, for the purposes of illustration the invention is incorporated in a fuel injection system of the mass air flow type substantially as shown and described in the aforenoted copending Dolza application.
Briefly, the fuel injection system includes an air intake passage it having a tapered diffuser element 12 disposed therein and cooperating therewith to define an annular venturi 14. A throttle valve 16 is disposed in the intake passage and which passage communicates with air plenum chamber 18. A plurality of intake passages 20 communicate the plenum chamber with each of the individual cylinders 22 of an internal combustion engine. A fuel metering mechanism is provided generally at 24 and includes a fuel reselyoir 26 supplied with fuel from an inlet conduit 23. The fuel level in reservoir 26 is controlled, in a conventional manner, by a float controlled inlet valve 30. A pump 32 is provided Within the fuel reservoir and is adapted to supply fuel under pressure to a fuel metering valve indicated generally at 34. The fuel metering valve in turn supplies fuel through a conduit 36 to a distributor 38 from which individual fuel conduits iii deliver fuel to nozzies 42 disposed in each of the intake passages 20.
The fuel metering valve 34 includes a member 44 slidably disposed in a casing 46 and which member is adapted to coact with a spill or bypass passage 48 to control the quantity of fuel supplied to outlet conduit 36. Thus, as the slidable valve element 44 moves to uncover spill passage 48 less fuel is supplied to conduit as and conversely as the spill passage is progressively restricted the quantity of fuel supplied to conduit 36 is increased. The slidable valve element 44 is operatively connected through a linkage device 56) to a metering control diaphragm 52 suitably mounted in the fuel reservoir casing The actuation of diaphragm 52 is determined by the mass of air flow through venturi l4. Venturi 14- is communicated with an annular chamber 56 within which is created a vacuum force proportional to mass air flow. This vacuum force is then communicated with the diaphragm 52 through a conduit 58. Accordingly, as the mass of air fiow through the intake passage 12 increases, the increased vacuum force in conduit 58 causes diaphragm 52 to be moved upwardly moving the slidable valve element 44 downwardly to progressively restrict the spill passage 48.
Referring to Figure 3 it will be seen that the atmospheric nozzles 42 includes a casing portion 60 mounted upon the end of fuel conduit 46. A pair of arially spaced orifices 62 and 6 3 are formed in casing 60. Orifice 62 is a fuel metering orifice which is adapted to target a fuel stream throughthe larger air metering orifice 64. A plurality of radiating passages 66 are formed through casing cc and centrally define a space or chamber 68 which is maintained at whatever pressure obtains within a manifold '79 commonly communicating with all the nozzles 42. in the non-pressurized version of the subject system, as described in the afo-renoted Dolza applicahen, the manifold 7d and nozzle chamber 68 weremaintained at substantially atmospheric condition whereby manifold vacuum acting on the shroud end 72 of nozzle 512 would be neutralized so as to have no effect on the quantity of fuel flowing through the metering orifice 62.
In order to pressurize the present fuel system, a suitable source of air under pressure is provided. While any suitable air pressurizing means may be utilized, a single cylinder compressor 74, as best seen in Figure 2, has been illustrated. A compressor piston 7c may be conveniently driven from a single throw crankshaft 78 which may also be utilized to drive fuel pump 32. Compressor '74 further includes spring biased inlet and outlet valves 80 and 82. Outlet valve 82 is adapted to communicate with a conduit 84 to supply air under pressure to pressure storage tank 86. A supply conduit 88 leads from the storage tank 86 and may include suitable pressure relief valve 90. While any reasonable air pressure may be maintained, for purposes of illustration, valve 99 may be set for 25 psi.
It is desirable to supply air to inlet valve 80 through a conduit 81 connecting at its other end with induction passage intermediate venturi 14 and throttle lie. In this way air flow through the venturi is increased which insures a strong vacuum metering signal on diaphragm 52.
Air under pressure is supplied to nozzle air manifold 70 and from there conduit 92 pressurizes the fuel in reservoir 26. Since the fuel is placed under 25 psi, it is necessary to create a corresponding back pressure at nozzle 42, as an alternative to reducing the size of nozzle fuel orifice 62, to maintain the desired fuel flow rate. This back pressure is achieved supplying the nozzle manifold air from supply conduit 83, supra. in this way the fuel system may be maintained under sufficient pressure to prevent fuel vaporization therein without interfering with the fuel flow rate otherwise determined by the fuel metering mechanism.
In a non-pressurized system the nozzle air metering orifice 64 might be approximately .040". However, in pressurizing the reference air suppliedto nozzles, supra, it becomes necessary to reduce the size of orifice 64 in order not to increase the engine idling speed by supplying excess idle air. Thus, when pressurizing to 25 p.s.i., given as an example, it would be necessary to reduce the air metering orifice to approximately .028". Even as reduced, however, the orifice 64 is still substantially larger than fuel metering orifice 62.
Inasmuch as reservoir 26 is maintained under superatmospheric pressure, e.g. 25 p.s.i., a reasonably good seal must be maintained between the reservoir and lower diaphragm chamber 53 in order not to upset the metering function of diaphragm 52. This is achieved by providing a suitable seal 55 between diaphragm control rod 57 and reservoir casing 54. Additionally, chamber 53 is vented substantially to atmospheric pressure through a conduit 59 communicating with induction passage 10 anteriorly of venturi 14. In these ways it is insured that actuation of diaphragm 52 will be in accordance with mass air flow through venturi 14.
It is, of course, apparent that the output pressure of fuel supplied by pump 32 to reservoir 26 must exceed the superatmospheric pressure applied to the reservoir by compressor 74.
It is apparent that the invention as illustrated may be modified or adapted to other fuel systems within the scope of the hereinafter appended claims,
1. A charge forming device for an internal combustion engine comprising an air intake passage, a throttle valve in said passage, a plurality of induction passages communicating said intake passage with the individual cylinders of the engine, a fuel nozzle in each of said induction passages, a fuel metering mechanism for supplying metered quantities of fuel to each of said nozzles, said metering mechanism including a fuel reservoir, each of said nozzles comprising a fuel metering orifice, an
air metering orifice axially spaced from said fuel metering orifice, an air chamber intermediate said orifices, a common air manifold communicating the respective nozzle air chambers, a source of air under superatmospheric pressure, conduit means communicating said air pressure source, said air manifold and said fuel reservoir whereby said nozzle air chambers and said reservoir are maintained under superatmospheric pressure.
2. A charge forming device for an internal combus tion engine comprising an air intake passage, a throttle valve in said passage, a plurality of induction passages communicating said intake passage with the individual cylinders of the engine, a fuel nozzle in each of said induction passages, a fuel metering mechanism for supplying metered quantities of fuel to each of said nozzles, said metering mechanism including a fuel reservoir, each of said nozzles comprising a fuel metering orifice, an air metering orifice axially spaced from said fuel metering orifice, an air chamber intermediate said orifices, a common air manifold communicating the respective reference air chambers, and means for maintaining said air manifold and fuel reservoir under superatmospheric pressure.
3. A charge forming device for an internal combats-- tion engine including an intake passage for each engine cylinder, a fuel nozzle disposed in each intake passage proximate the associated engine cylinder, said nozzle including an air chamber through which fuel is sprayed prior to entering the intake passage, means for supplying: metered quantities of fuel to each nozzle, said means in eluding a fuel reservoir, and means for maintaining eacls nozzle air chamber and fuel reservoir under superatmospheric pressure.
4. A charge forming device as set forth in claim 3 in. which the superatmospheric pressure maintaining means comprises an air pump, a reservoir for storing the air. under pressure from said pump, and conduit means inter-- connecting said air reservoir, said nozzle air chambers and said fuel reservoir.
5. A charge forming device for an internal combustion engine comprising an air intake passage, a throttle valve in said passage, a plurality of induction passages communicating said intake passage with the individual cylinders of the engine, a fuel nozzle in each of said induction passages, a fuel metering mechanism for sup-- plying metered quantities of fuel to each of said nozzles, said metering mechanism including a fuel reservoir, a pump in said reservoir for supplying fuel under pres-- sure to said nozzles, each of said nozzles comprising a fuel metering orifice, an air metering orifice axially spaced. from said fuel metering orifice, an air chamber inter-- mediate said orifices, a common air manifold communicating the respective reference air chambers, a pump for pressurizing air, a pressurized air reservoir, conduit means communicating said air reservoir, said air manifold and said fuel reservoir, and common drive means for said fuel and air pumps.
References Cited in the file of this patent UNITED STATES PATENTS 2,711,720 Nallinger June 28, 1955 2,829,873 Kupka Apr. 8, 1958 2,860,859 Dolza Nov. 18, 1958
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2711720 *||May 31, 1951||Jun 28, 1955||Daimler Benz Ag||Device for fuel injection in internal combustion engines|
|US2829873 *||Oct 22, 1956||Apr 8, 1958||Mckiernan Terry Corp||Pressure carburetor|
|US2860859 *||Sep 10, 1956||Nov 18, 1958||Gen Motors Corp||Fuel injection nozzle|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3182646 *||Jun 15, 1961||May 11, 1965||Alfred Kuechenmeister Craig||Air-bled coaxial injector|
|US3198498 *||Jul 2, 1962||Aug 3, 1965||Sibe||Pressure carburetors|
|US5054456 *||Nov 6, 1989||Oct 8, 1991||General Motors Corporation||Fuel injection|
|U.S. Classification||261/23.2, 261/78.1, 261/28|
|International Classification||F02M69/04, F02M69/00|
|Cooperative Classification||F02M69/00, F02M69/047|
|European Classification||F02M69/00, F02M69/04D|