Internal-combustion engines – Charge forming device
Patent
1984-09-27
1986-02-04
Nelli, Raymond A.
Internal-combustion engines
Charge forming device
123438, 123523, 123524, 261121A, 261 40, 261 72R, F02M 7093
Patent
active
045678715
DESCRIPTION:
BRIEF SUMMARY
The invention relates to the distribution and metering of fuel to the cylinders of a multi-cylinder internal combustion engine.
In order for an engine to operate efficiently, it is important for the mixture which it receives to be of the correct strength. Furthermore, in a multi-cylinder engine it is important to ensure that all cylinders receive comparable charges, i.e. the quantities of air as well as the mixture strengths received by the different cylinders should be the same.
In an engine in which fuel metering is effected by means of a single carburettor, the fuel mixture to all the cylinders should be the same but it is difficult to divide the charge equally between the cylinders. When several carburettors are provided, on the other hand, difficulty arises in balancing the mixture strength to all the cylinders. A still further problem with the use of carburettors is that fuel is present in the intake manifold and this can be troublesome if attempts are made to tune the manifold.
A fuel injection system has the advantage that the metering of the fuel is performed separately from the metering of the air supply to the cylinders. Thus the mixture strengths for the cylinders may be adjusted individually permitting more accurate control. Furthermore, the intake manifold design is simplified and the manifold is dry, which facilitates tuning of the manifold length and avoids the various problems caused by fuel in the manifold which tends to be deposited on the walls of the manifold and disturbs the mixture strength under transient conditions. The chief disadvantage of fuel injection, however, is the complexity, which is reflected in the cost and in reliability.
The present invention seeks to provide a system which offers the advantages of fuel injection but which may be implemented more simply.
According to the present invention, there is provided a fuel metering and distribution system for an internal combustion engine comprising an open fuel reservoir, a plurality of fine tubes each extending from the fuel reservoir to a point in an induction manifold adjacent the intake valve of a respective one of the engine cylinders, and means for introducing fuel into the reservoir at a controlled rate dependent upon the rate of air flow to engine cylinders, the ends of the fine tubes terminating in the fuel reservoir immediately above the fuel level, whereby as the fuel rises, the additional fuel metered into the reservoir is sucked into the fine tubes and transferred directly to the engine cylinders.
The fuel introduced at a controlled rate into the reservoir acts to raise the fuel level and the fine tubes which are under vacuum pressure draw the fuel so that once the fuel level in the reservoir attains equilibrium, all the fuel introduced into the reservoir is drawn by the intake manifold vacuum through the fine tubes to the cylinders while by-passing the air intake manifold. The fine tubes cannot however suck any more fuel than is metered into the reservoir.
An important feature of the air to fuel interface present within the reservoir is that it enables the cylinders to draw equal amounts of fuel from the reservoir without affecting the fuel metering function. In the absence of an air to fuel interface, such as if the reservoir is sealed or permitted to fill up with fuel then vacuum in the manifold would interfere with fuel metering and furthermore because the pressure cycles of the cylinders are not synchronised one cylinder may draw more of the metered fuel than the other cylinders.
The vacuum pressure in the manifold is sufficient to suck all the fuel from the reservoir without assistance under most operating conditions. However, to assist in the fuel transfer through the fine tubes under low vacuum conditions in the intake manifold, it is desirable to form a venturi in the intake manifold at the other end of each fine tube in order to reduce the pressure in the fine tubes.
It is also preferable, for the same reason, to arrange the reservoir at a level higher than the exit ends of the fine tubes so that gravit
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patent: 1365661 (1921-01-01), Couldonise
patent: 1791204 (1931-02-01), Harel
patent: 1845668 (1932-02-01), Keil
patent: 3273809 (1966-09-01), Morton
patent: 3419251 (1968-12-01), Eckert
patent: 3841613 (1974-10-01), Eckert
patent: 4399794 (1983-08-01), Gagnon
Ford Motor Company
McCollum Robert E.
Nelli Raymond A.
Sadler Clifford L.
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