US3782639A

US3782639A - Fuel injection apparatus

Info

Publication number: US3782639A
Application number: US00244441A
Authority: US
Inventors: R Boltz; W Ojala
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1972-04-17
Filing date: 1972-04-17
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: SE388246B; JPS4915818A; AU466662B2; GB1411037A; IT976989B; AU5098473A; DE2319034A1; JPS544444B2; CA973765A

Abstract

Apparatus for the injection of fuel into the intake manifold of an internal combustion engine is described. The apparatus includes an air-assist nozzle that has a chamber formed in it that includes an orifice for the discharge of air-atomized fuel. A fuel injector has a fuel discharge port positioned within the chamber of the air-assist nozzle. The air-assist nozzle has an air inlet to the chamber, and air which enters the chamber through the inlet mixes with the fuel discharged from the fuel injector producing an air-fuel atomized mixture which is discharged from the orifice of the air-assist nozzle.

Description

United States Patent 1191 Boltz et al. Jan. 1, 1974 [54] FUEL INJECTION APPARATUS 1,898,763 2/1933 Cowardin et: al. 239/403 x [75] Inventors: Ronald R. Boltz, Oak Park; William J a Dearbom Heights, both of 2,893,365 7/1959 Haefner 123/139 AW Mich.

[73] Assignee: Ford Motor Company, Dearborn, Primary Examiner-M Henson Wood, 113

Mich Assistant Examiner-John J. Love Attorney-Keith L. Zerschling et al. [22] Filed: Apr. 17, 1972 [21] Appl. No.: 244,441 [57] ABSTRACT Apparatus for the injection of fuel into the intake 52] us. c1 239/405, 239/4345, 239/470, manifold of an internal Combustion F 2 is 239/533, 239/585, 123/139 AW scribed. The apparatus includes: an alr-assist nozzle 51 rm. (:1 BOSb 1/34 that has a chamber formed in it that includes an 58 Field of Search 239/403, 405, 468, fice for the discharge of air'atomiled fuel- A fuel 239/469, 470, 585, 533, 399, 401, 434.5; jector has a fuel discharge port positioned within the 123/139 w chamber of the air-assist nozzle. The air-assist nozzle has an air inlet to the chamber, and air which enters [56] References Cited the chamber through the inlet mixes with the fuel dis- UNITED STATES PATENTS charged from the fuel injector producing an air-fuel atomized mixture which is discharged from the orifice 1,495,731 5/1924 Gerdes et al 239/405 of the air assist nozzle 2,755,134 7/1956 Eck et a] 239/403 X 1,457,849 6/1923 Morse 239/405 1 Claim, 3 Drawing Figures FUEL INJECTION APPARATUS BACKGROUND OF THE INVENTION This invention relates to apparatus for injecting fuel into the intake manifold of an internal combustion engine and, more particularly, to fuel injection apparatus including an air-assist nozzle having a swirl chamber within it which, in combination with a fuel injector that may be of conventional design, produces a highly atomized mixture of air and fuel that is discharged into the intake manifold of an internal combustion engine. The invention is applicable to both electronic and mechanical fuel injection systems for internal combustion engines.

Fuel injection systems for internal combustion engines have undergone much development over the years. Fuel injection systems for such engines fall into two broad classes, that is, those in which fuel is injected directly into the engines combustion chambers and those in which fuel is injected into an intake passage preceding the combustion chambers. The teachings of the present invention are particularly applicable to fuel injected engines in the latter classification, but are believed to be applicable to the former class of fuel injected engines also.

One of the greatest problems encountered in the application of fuel injection systems to internal combus tion engines is in finding means for achieving adequate atomization of the fuel injected into the engine. If the fuel is inadequately atomized in the combustion air, incomplete combustion may result and it may be necessary to supply a greater quantity of fuel to the engine than would otherwise be required were the atomization of the air and fuel adequate. Where the amount of fuel injected into an engine exceeds the amount which can be consumed in the engine combustion process, the engine necessarily must discharge the excess fuel to the atmosphere as a part of its exhaust emission. Also, inadequate atomization of the fuel can have a detrimental effect on the performance of an engine, particularly when the engine is cold and fuel injected into it is likely to impinge on engine parts and condense.

SUMMARY OF THE INVENTION The fuel injection apparatus of the invention comprises an air-assist nozzle having a chamber within it. The chamber has an air inlet passage in communication with the chamber. The chamber in the air-assist nozzle has a cylindrically shaped first portion and a coaxial frusto-conically shaped second portion. The air inlet passage to the chamber approaches the cylindrically shaped portion thereof from a substantially tangential direction. The air-assist nozzle also has an orifice for the discharge of air-atomized fuel. The orifice communicates with the chamber at the smaller diameter end of the frusto-conically shaped second chamber portion. Means, such as a commercially available fuel injector, is used with the air-assist nozzle for the discharge of fuel into its chamber. The fuel discharge means includes a fuel discharge nozzle that is positioned within the chamber of the air-assist nozzle. Preferably, this fuel discharge nozzle has a discharge port positioned on the axis of the air-assist nozzle chamber and the discharge port is axially spaced from the orifice in the airassist nozzle.

Preferably, the fuel injection apparatus of the invention is-used to inject fuel into an air intake passage preceding the combustion chamber of a reciprocating or rotating internal combustion engine. In such engines, a throttle valve is used to control the air entering the air intake passage. In an engineof this type, the air pressure in the air intake passage is less than atmospheric pressure during engine operation, but fluctuates from a very low absolute pressure to almost atmospheric pressure depending on engine speed, throttle angle position, exhaust system back pressure and the like. The air-assist nozzle described above, when used in conjunction with means for discharging fuel intoits chamber, effectively isolates the fuel discharge means from the fluctuations in air intake passage pressure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of fuel injection apparatus constructed in accordance with the invention and positioned in a portion of an intake manifold of an internal combustion engine;

FIG. 2 is an enlarged sectional view ofthe fuel injection apparatus of FIG. 1, the location at which the sectional view of FIG. 2 is taken being indicated by the line 2-2 in FIG. 3; and

FIG. 3 is an enlarged sectional view of the fuel injection apparatus, the section being taken along the line 3-3 indicated in FIG. 2.

DETAILED DESCRIPTION With reference now to the drawings, wherein like numerals refer to like parts in the several views, there is shown fuel injection apparatus constructed in accordance with the invention.

FIG. 1 is a sectional view ofa portion of the cylinder head and air intake manifold of a reciprocating internal combustion engine which utilizes fuel injection in its operation. The cylinder head 10 is of conventional construction and includes an intake poppet valve 12 which, when opened, permits a mixture of air and fuel to be drawn through the intakeport 1-4 into a combustion chamber (not shown) below the cylinder head 10. Combustion air is supplied to the cylinder head 10 through an air passage 16 in an air intake manifold 18 that is attached to the cylinder head 10.

Fuel injection apparatus, generally designated by the numeral 20, is mounted in an opening 22 in the intake manifold 18 and is positioned therein such that a mixture of atomized air and fuel 24, when discharged from the fuel injection apparatus 20 is directed toward the intake valve 12 and intake port 14. The fuel injection apparatus 20 comprises an air-asist nozzle 26 having a chamber 28 within it, and means for discharging fuel into the chamber 28 in the form of an electromagnetic fuel injector 30. An air inlet 29 communicates with the chamber 28 of the air-assist nozzle. The air-assist nozzle 26 and fuel injector 30 are held in position in the intake manifold 18 with a plate 32, which is fitted into a groove 34 in the fuel injector, and bolts 36 and 38 threaded into the intake manifold.

FIGS. 2 and 3 are enlarged sectional views of the fuel injection apparatus 20. It may be seen that the air-assist nozzle 26 is comprised of a nozzle body 40, a nozzle orifice insert 42, and an annular thermal insulator 44, which may be made from a material such as micarta. The nozzle body 40 has a cylindrically shaped opening 46 which is threaded at one end to receive the nozzle orifice insert 42. The orifice insert 42 has a frustoconically shaped portion 48 which, when positioned in the nozzle body 40 as shown in FIG. 2, is coaxial with the cylindrical opening 46 in the nozzle body and which, with the nozzle body, forms the chamber 28. Thus, the chamber 28 has a cylindrical-shaped first portion and a coaxial frusto-conically shaped second portion. An orifice 50 in the nozzle orifice insert 42 communicates with the chamber 28 at the smaller diameter end of the frusto-conically shaped second chamber portion. The air-assist nozzle 26 may be formed from a single piece, if desired. Also specific dimensions of the air-assist nozzle 26 are important and are affected by the design'of the fuel injector 30.

The air inlet 29 preferably communicates with the cylindrically shaped-first portion of the chamber 28 and approaches this cylindrically shaped. portion of the chamber from a direction that is tangential with respect to the cylindrical opening 46,- as may best be seen in FIG. 3.

Where the internal combustion engine is controlled by means. of an airthrottle.(n ot shown) positioned in the intake manifold 18, the air pressure within the flow passage 16 of the manifold fluctuates from very low absolute pressuresat engine idling conditions to absolute pressures'near atmospheric pressure during wide open throttle operation of the engine. Intake manifold pressure also fluctuates with time (crank engine angle) at a fixed average manifold pressure. In the absence of the air-assist nozzle this creates a varying differential pressure acrossthe discharge nozzle of the fuel injector 30. It is an object of the invention to isolate the fuel injector 30 from the intake manifold pressure fluctuations. For this reason, the air inlet 29 to the chamber 28 of the air-assist nozzle preferably is connected to a source of air which is at or near atmospheric pressure. The effect of this on the operation of the fuel injection apparatus 20 is described hereinafter.

The fuel injector 30 is of a design presently in commercial use. It comprises an injector body 52 that is positioned in the annular insulator 44 of the air-assist nozzle 26, which thermally isolates it from the air-assist nozzle. An air space 54 between the insulator 44 and the nozzle body 40 aids in this thermal isolation.

The injector body 52 has a fuel discharge nozzle 56 positioned within it. The nozzle 56 has a fuel discharge port 58, which includes a valve seat 60, that is positioned within the cylindrically shaped first portion of the chamber 28 and preferably is located as shown on the common axis 62 of the cylindrically shaped and frusto-conically shaped portions'of the chamber 28.

Also, it is preferable that the discharge port 58 of the fuel nozzle 56 be axially spaced from the orifice 50 and that it be positioned intermediate the air inlet 29 and the orifice 50, as may best be seen in FIG. 2.

The fuel injector 30 is electromagnetically operated by a coil 64 which, when energized, moves an armature 66 against the force of a spring 68. Fuel enters the injector 30 through an inlet 70 and travels through a passage 72 and is then deposited in a chamber 74 in the fuel nozzle 56.

' As the air is drawn toward the orifice 50 in the nozzle insert 42', its angular velocity increases because of the frusto-conically shaped portion of the chamber 28. This swirling air mixes with the fuel discharged in the chamber 28 from the fuel discharge port 58 and results in a finely atomized mixture of air and fuelbeing discharged through the orifice 50 into the intake manifold passage 16.

It should be noted that the discharge port 58 of the fuel injector 30 is isolated from the fluctuating subatmospheric pressure in the intake passage 16 by the atmospheric air which enters the swirl chamber 28 of the air-assist nozzle and that a variable pressure drop will occur across the orifice 50 of the nozzle insert. In practice, very excellent air and fuel atomization has been obtained with an air-assist nozzle in which the orifice 50 has a length to diameter ratio of 1.0 and in which the frusto-conically shaped portion of the chamber 28 forms angle of 45 with respect to the axis 62. 1

Based upon the foregoing description of the invention, what is claimed and desired tobe protected by Letters Patent is:

L'Apparatus for the injection of fuel into the intake manifold of an internal combustion engine, said apparatus comprising: an air-assist nozzle positioned in said engine intake manifold, said air-assist nozzle having a chamber formed in it, said chamber having a cylindrically shaped first portion and a coaxial frusto-conically tion from a tangential direction; and means for dis- I charging fuel into said air-assist nozzle chamber, said fuel discharge means having a discharge port located within said chamber, said discharge port being positioned on the axis of said chamber in said air-assist nozzle and being located within said cylindrically shaped first portion of said air-assist nozzle chamber, said discharge port being axially spaced from said air-assist nozzle orifice and being positioned intermediate said air-assist nozzle air inlet passage and said air-assist nozzle discharge orifice.

Claims

1. Apparatus for the injection of fuel into the intake manifold of an internal combustion engine, said apparatus comprising: an air-assist nozzle positioned in said engine intake manifold, said air-assist nozzle having a chamber formed in it, said chamber having a cylindrically shaped first portion and a coaxial frustoconically shaped second portion, said air-assist nozzle having an orifice for the discharge of air-atomized fuel from said chamber into said engine intake manifold, said orifice communicating with said chamber at the smaller diameter end of said frusto-conically shaped second chamber portion, said air-assist nozzle having an air inlet passage in communication with said cylindrically shaped first chamber portion, said air inlet passage approaching said cylindrically shaped first chamber portion from a tangential direction; and means for discharging fuel into said air-assist nozzle chamber, said fuel discharge means having a discharge port located within said chamber, said discharge port being positioned on the axis of said chamber in said air-assist nozzle and being located within said cylindrically shaped first portion of said air-assist nozzle chamber, said discharge port being axially spaced from said air-assist nozzle orifice and being positioned intermediate said air-assist nozzle air inlet passage and said air-assist nozzle discharge orifice.