GB2172654A - Air-fuel mixture supply system for multi-cylinder I.C. engine - Google Patents

Abstract

A multi-cylinder engine is provided with individual intake manifold runners (16) connected to a plenum (18) which is connected to the air induction passage (22) of an air throttle body (24) for the main supply of air to the engine. The fuel supply is provided by a single fuel injection (54) located to discharge into an air- assist chamber (60) supplied with air by a line (62) and which communicates with a fuel distributor (64,66) rotatable by the engine and provided with a passage (70) that is aligned in turn with passages (72) connected to the individual intake manifold runners (16). <IMAGE>

Description

SPECIFICATION Air assisted fuel distributed air-fuel supply system This invention relates in general to an air-fuel supply system for an automotive type internal combustion engine. More particularly, it relates to one that includes an air throttle body delivering the main supply of air essentially at atmospheric pressure from an air cleaner to the intake manifold of the engine, and a fuel injector supplying equal amounts of aerated fuel to each cylinder of the engine through individual runners by means of a single rotating fuel distributor.

It is a primary object of the invention to provide accurate fuel distribution to the individual cylinders of the engine from a single fuel injector located remote from the conventional air throttle body.

A further object of the invention is to provide an air-fuel supply system in which fuel atomization is improved by air atomization, permitting the use of lower cost injector designs and a reduction of the general fuel pressure requirements, as well as a reduction in wall wetting, which results in a reduction in intake manifold heating requirements. These improvements result in a higher engine power and output, reduced CO emissions, an improvement in the overall fuel efficiency, and an improvement in engine cold start properties including fuel efficiency and vehicle drivability.

The use of a rotating fuel distributor to provide a more uniform distribution of the fuel to the individual engine cylinders is known. For example, U.S. 2,730,339, Presnell, shows a fuel distributor rotor 19 driven by the engine to sequentially align the fuel charge with the individual manifold runners. In this case, the fuel is mixed only with the air inducted through the throttle body: no additional air is supplied to atomize the fuel prior to discharge into the individual runner. Also, the injector and distributor are not remotely located from the throttle body.

U.S. 3,046,894, Machen, shows a reciprocating type fuel injection pump with a fuel pumping chamber; however, there is no separate air supply to the pumping chamber for atomizing the fuel since the pump in effect constitutes an injector, the output of which is controlled by intake manifold vacuum and temperature changes.

U.S. 3,267,921, Whitehurst, shows an air throttle body and a single point injector discharging fuel into a plenum connected to the engine cylinders; however, there is no separate air supply to atomize the fuel, nor is the fuel supply remote from the throttle body, and connected to separate runners connected individually to the engine cylinders for an equal supply of fuel to each cylinder.

U.S. 3,742,923, Oblander et al, shows an air throttle body induction passage connected to a plenum from which individual runners are connected to the engine combustion chambers for the main supply of fuel and air. An air bypass passage from the air cleaner is connected to an air chamber into which idle speed fuel is sprayed from an injector, a distributor being provided to supply crankcase vapors and an air-fuel mixture to two of the manifold runners. The injector in this case is only for starting purposes and does not supply the main fuel volume individually to each of the manifold runners.

None of the above references provide a fuel distribution system from a single fuel injector that includes a supply of additional air to atomize the fuel, the fuel then being delivered through a rotating distributor individually to each of the engine cylinders to assure an equal supply of fuel to all cylinders, the main supply of air being supplied through a conventional throttle body connected to a plenum from which individual runners are cdnnected to each engine cylinder and receive the fuel charge therein from the fuel distributor.

According to the present invention there is provided an engine air-fuel system for an internal combustion engine as herein set forth in Claim 1.

The invention will now be described further by way of example with reference to the accompanying drawings, in which: Fig. 1 schematically illustrates a cross-sectional view of an air-fuel supply system embodying the invention; and Fig. 2 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows ll-ll of Fig. 1.

Fig. 1 shows a portion 10 of a four-cylinder combustion engine having cylinder bores 12 provided in an engine block, not shown, and cooperating with a plurality of air-fuel intake ports 14. Each of the ports is individually connected to an intake manifold runner 16 connected at its opposite end to a plenum 18.

The plenum has a central opening 20 connected to the lower end of an induction passage 22 provided in an air throttle body 24.

Located over the top 26 of the induction passage is a conventional dry element type air cleaner 28 having an annular filter 30 through which air at atmospheric or ambient pressure enters through an inlet snorkle 32 in a known manner.

The induction passage 22 contains a butterfly type throttle valve 34 mounted in the walls of throttle body 24 for a pivotal movement between the nearly closed position indicated and more open vertical positions to control the flow of air through the passage.

Mounted above throttle valve 34, for a purpose to be described in more detail later, is a second butterfly type valve 36. The latter also is mounted for rotation in the throttle body, and has fixed thereto a link 38 connected by a rod 40 to a diaphragm type servo mechanism 42. The latter consists of a shell type servo housing 44 divided by an annular flexi ble diaphragm 46 into an atmospheric air chamber 48 and a vacuum chamber 50. The vacuum chamber is connected by a pipe 52 to induction passage 22 at a location between the two butterfly valves 34 and 36. A spring 53 biases the diaphragm and valve 36 to a valve closed position.

As will be clear as thus far described, the suction created by operation of the engine will induce a vacuum in the runners 16 and induction passage 22 to draw air at essentially atmospheric or ambient pressure level through air cleaner 28 to supply clean air into the individual engine cylinders.

The supply of fuel to the engine in this case is provided from a single point type fuel injector indicated in general at 54 remotely located from the air throttle body. The injector would be of a known construction providing an electronically pulsed flow of fuel in accordance with a predetermined schedule as determined by a microprocessor, not shown, to always supply the correct amount of fuel in accor dance with the operating conditions of the en gine. The fuel in this case is supplied to injector 54 from a supply line 56, an electrical wiring harness 58 connecting the injector to the microprocessor. The fuel is injected in a conical-like pattern from injector 54 into the top of an air chamber 60 supplies with air by a line 62 connected to the clean air side of air cleaner 28.Directly beneath and aligned with the fuel injector nozzle is a fuel distributor ro tor 64 rotatably mounted inside a distributor body 66.

The distributor rotor 64 is provided with an axial passage 68 flush with the lower wall of chamber 60 and concentrically aligned with the axis of fuel injector 54 and the distributor.

Passage 68 intersects a radial passage 70 that breaks through the cylindrical surface of the rotor, as indicated. As best seen in Fig. 2, the radial passage 70 is adapted to be aligned on a one-at-a-time basis with four air-fuel mix ture ports spaced 90 apart and individually connected by passages 72 to the separate manifold runners 16, as indicated. This is ac complished by the distributor rotor 64 being mounted on bearings 74 with its shaft syn chronousiy rotated by the engine crankshaft, not shown, through a gear system at one-half the crankshaft velocity.

Thus, the fuel would be injected into cham ber 60 and axial passage 68 and mixed with the air supplied by bypass passage 62 that atomizes the fuel and provides a good air-fuel mixture for flow into the engine combustion chambers. An air path will be established between the air cleaner and the particular branch 16 of the intake manifold into which intake air also is being inducted through main induction passage 22. Due to the intake manifold depression, an air-assist flow is established which carries the atomized fuel to the appropriate manifold branch 16 and evenly divided between all of the branches. Any leakage flow that may occur-between the outside diameter of the distributor rotor and its housing does not affect this operation.

From the above, therefore, it will be seen that the invention provides an air-fuel supply system in which the main supply of air occurs through a conventional air throttle body to the individual manifold runners and fuel is supplied directly and individually to the manifold runners through a remotely located fuel distributor and an air assist chamber that not only atomizes the fuel but carries the fuel to the engine cylinders.

The system as described above provides adequate air-assist flow during normal engine operation other than during cranking and other low manifold vacuum levels. The butterfly valve 36 and servo 42, however, assures sufficient air-assist flow through the distributor under cranking and other low manifold vacuum conditions; i.e., they provide a minimum intake vacuum regulator system. The spring loaded diaphragm 46 maintains the regulator valve 36 closed, the diaphragm automatically opening the valve in response to the level of vacuum between the two butterfly valves 36 and 34 to obtain the desired minimum intake vacuum.

It will be clear that the minimum vacuum regulator could be replaced by an optional airassist pump, driven either by the engine or by an electric motor in order to further increase the air atomization by higher air velocities past the fuel injected from injector 54.

The preferred embodiment utilizes an electronic pulse modulated fuel injector 54, as described. However, it will be clear that the advantages of this fuel distribution system could be obtained with other type controllable interrupted or continuous fuel discharge devices.

Such modification would be possible because the injector is not required to atomize the fuel, and equal distribution of the fuel to each cylinder can be achieved by proper design of the distributor itself.

This particular air-fuel system provides fuel for engine cylinders having non-simultaneous intake strokes. When simultaneous injection periods are required, more than one distributor would be used.

From the foregoing, it will be seen that the invention provides an air-fuel system that provides accurate fuel distribution in internal combustion engines from a remotely located fuel injector to each of the engine cylinders. It will also be seen that the invention provides fuel atomiziation by air atomization, which eliminates the necessity of providing atomization in the fuel injector itself, thereby facilitating the use of lower cost injector designs and a minimizing of the general fuel pressure requirements, and that the air-assist flow path and atomization of the fuel will reduce wall wetting and thereby reduce the intake manifold heating requirements.

Claims (7)

1. An engine air-fuel supply system for an internal combustion engine having a number of cylinders and an intake manifold having a plenum at one end and a like number of individual runners emanating therefrom connected to the individual cylinders for the flow of fuel and air thereinto, the system including an air throttle body having an air induction passage open at one end to air at essentially atmospheric pressure and connected at its opposite end to the intake manifold plenum to be subject to the pressure variations therein, a throttle valve mounted in the passage for rotation there-across to variably control air flow to the individual engine cylinders, a number of fuel passages equal in number to the number of cylinders and separately connected at one end each to an individual runner, and fuel distribution means remotely located from the throttle body and connected to the opposite ends of the passages for supplying fuel thereto, the distribution means including an air chamber connected to a source of air, a single fuel injector injecting fuel into the air chamber at one portion for mixing with the air therein to atomize the fuel and provide a mixed air-fuel charge, and a rotatable engine driven charge distributor rotor connected to an opposite portion of the air chamber downstream of the injector and axially aligned therewith, the distributor rotor having an axial inlet passage receiving the charge therein from the chamber and injector and having a single side exit passage connected to the axial passage, the distributor being rotatably mounted in a stationary housing having a number of equally circumferentially spaced ports, corresponding in number to the number of fuel passages and connected individually to the fuel passages and alignable one at a time with the side exit passage upon rotation of the distributor rotor to sequentially supply fuel to each of the fuel passages, the vacuum in the intake manifold establishing an air flow through the air chamber to the cylinders in addition to the air flow through the induction passage, the air flow through the chamber carrying the fuel therewith equally distributed to the individual runners.

2. A supply system as in Claim 1, including an engine air cleaner receiving air at essentially atmospheric pressure therein and discharging the air into the one end of the induction passage, and including an air line connected from the air cleaner to the air chamber for the supply of air thereto at essentially the same pressure level as to the induction passage.

3. A supply system as in Claims 1 or 2, including a spring closed induction passage vacuum regulating butterfly air valve mounted in the induction passage upstream of the first mentioned throttle valve; and means connected to the air valve for variably opening the same as a function of the level of vacuum in the induction passage between the throttle and air valves to assure an induction of air through the air chamber to the runners at low manifold vacuum level conditions and during engine cranking.

4. A supply system as in Claim 3, wherein the last mentioned means comprises a vacuum diaphragm type servo operatively connected by a vacuum line to the induction passage between the valves.

5. A supply system as in Claims 1 or 2, wherein the engine includes an air-fuel intake valve associated with each cylinder runner, the valves operating with non-simultaneous intake strokes.

6. A supply system as in Claim 1, including air pump means connected to the air chamber for supplying adequate air under pressure thereto at high air velocities regardless of the level of manifold vacuum, the high air velocity atomizing the fuel.

7. An engine air-fuel supply system for an internal combustion engine-substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.