Fluid handling – With leakage or drip collecting
Patent
1983-08-26
1985-11-26
Walton, George L.
Fluid handling
With leakage or drip collecting
123531, 123533, G01F 1138, F02M 6700
Patent
active
045549451
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an improved apparatus for delivering metered quantities of liquid such as fuel to an internal combustion engine.
In the following discussion of the invention and description of the practical arrangements specific reference is made to the apparatus for metering fuel but it is to be understood that the invention is not limited to that particular application.
One problem with many known apparatuses for delivering metered quantities of fuel is the leakage of fuel, and this problem is increased by the relatively high pressures used to inject the metered quantity of fuel. In currently used apparatus the pressure is commonly developed by a mechanical mechanism, such as a piston, which acts directly on the fuel. These constructions require the provision of effective seals between the piston and the chamber in which it operates, as leakage past the piston substantially influences the metering accuracy. It will be appreciated that the metered quantity of fuel each cycle is relatively small and thus any degree of leakage can significantly influence the accuracy of the fuel metering.
In French Patent No. 521309 there is disclosed a carburettor pump for two-stroke engines wherein there is delivered a charge of air under pressure to the working cylinder of the engine, and a measured quantity of fuel is picked up by the charge of air as the air travels to the working cylinder of the engine.
Accordingly, the fuel is not truly injected but is merely moved to a position within the stream of air, and that stream of air basically atomizes and/or vaporises the fuel so that it becomes entrained in the stream of air.
As the disclosure in this specification is not related to a true injector system, the fuel will only be subjected to relatively low pressures, particularly as the fuel is not required at any stage to be injected into the working cylinder of the engine against the pressures in the working cylinder. Accordingly, the sealing problems and the fine tolerances which are encountered in normal fuel injection systems would not be present in the system disclosed in this specification.
In addition, the chamber in which the quantity of fuel is measured is required to be moved into and out of the passage of the air once each revolution of the engine. There would thus be considerable wear of the working parts, which must lead to fuel leakage and in this construction leakage results in loss of accuracy in the quantity of fuel delivered. Also the degree of movement necessary and the speed and frequency of that movement, result in substantial inertia forces associated with the movement, which adversely affect the accuracy of fuel metering.
French Patent No. 2050728 discloses a true fuel injection metering arrangement wherein the fuel is displaced from a metering chamber by a gas under high pressure that injects the measured quantity of fuel into the working chamber of the engine. Apart from its high pressure operation, in most other regards, the injection system of this prior specification is very similar to that of French Patent No. 521309. It still requires the chamber that effects the metering of the fuel to be moved between a position in which it receives the fuel to a position at which the fuel is discharged from the chamber by high pressure gas.
The difference between the two French constructions is that in one the member carrying the chamber is subjected to a reciprocating movement, whereas, in the other it is subjected to a rotatory movement. The extent of the movement of the member carrying the chamber in French Patent No. 2050728 is relatively small which is desirable from the point of view of reducing wear, however, it is not a continuous rotary motion but an oscilatory motion. The chamber member would, during each cycle, oscillated through one-quarter of a revolution in each direction with a stationary period between each movement. This type of intermittent movement does of course increase the rate of wear between the mating moving surfaces, and hence the maintaining of an effective seal between
REFERENCES:
patent: 1868767 (1932-07-01), Ross
patent: 2706976 (1955-04-01), Gianini
patent: 4376423 (1983-03-01), Knapstein
Orbital Engine Company Proprietary Limited
Walton George L.
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