Gas and liquid contact apparatus – Fluid distribution – Valved
Patent
1986-05-23
1987-06-23
Miles, Tim
Gas and liquid contact apparatus
Fluid distribution
Valved
123327, 261DIG19, F02M 712
Patent
active
046751351
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an engine intake system incorporating a deceleration valve.
A deceleration valve is used to allow sufficient air to reach the engine when the throttle is closed with the engine running at speed, i.e. when the engine has to decelerate. Under these conditions, the mixture trapped in the manifold is fuel rich, and this may lead to undesirably high hydrocarbon emissions on deceleration. The use of a deceleration valve to admit air to the engine under these conditions can held to reduce these emissions.
In conventional deceleration valves, manifold vacuum works on a diaphragm, in opposition to a spring. Such valves have been found to be unreliable in that they have a tendency to stick.
According to the present invention, there is provided an engine intake system, engine, including a carburettor, a deceleration valve having a valve member operative to open and close a deceleration passage which bypasses the main air passage through the carburettor, and a housing divided by a diaphragm into two pressure chambers, one chamber being supplied with manifold vacuum and the other chamber being supplied with idle vacuum, and an auxiliary valve connected in the inlet to said other chamber and adapted to admit vacuum when the engine is idling, and to trap idle vacuum in the chamber when the engine is not idling, the valve member being connected to the diaphragm so that movement of the diaphragm opens and closes the deceleration valve.
The use of two pressure chambers means that diaphragm movement is always positive because the diaphragm is biassed from both sides. In addition, the valve automatically sets itself to close at the correct vacuum level as the idle vacuum which acts to tend to close the valve is reset each time the engine returns to idle.
The valve may include biassing means, such as a helical spring, for biassing the diaphragm in the direction of one of the chambers.
The auxiliary valve may be a two-position, three-port valve with a first port permanently connected to manifold vacuum, a second port connected to the inlet to said one chamber and the third port connected to the inlet to said other chamber. The auxiliary valve can be controlled so that it takes up one end position when the engine is idling, and an opposite end position at other times. When the engine is idling, manifold vacuum (which is idle vacuum at this stage) is passed to said other chamber. When the engine is not idling, manifold vacuum is passed to said one chamber and idle vacuum is trapped in said other chamber.
The auxiliary valve can be controlled by spark port vacuum which is zero when the carburettor butterfly is closed, but which rises to a high valve as soon as the butterfly is opened. A vacuum sustain valve can be placed between the vacuum spark port and the auxiliary valve, to prevent the auxiliary valve from switching as soon as the spark port vacuum drops.
The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view of a deceleration valve and a control valve in accordance with the invention;
FIG. 2 is a section through the deceleration valve of FIG. 1;
FIG. 3 shows an alternative engine intake system in accordance with the invention;
FIG. 4 is a section through an auxiliary valve for use in the system of FIG. 3;
FIG. 5 is a graph showing how various vacuum levels change with throttle angle.
A deceleration valve 10 has a passage 12 (see FIG. 2) for bypass air. The passage has an inlet 14 connected to a carburettor and an outlet 16 connected to an intake manifold. A valve member 18 sits in the passage and can open, close or throttle the passage 12.
The passage 12 bypasses the air passage through the barrel 20 of a carburettor to which it is fitted. When the throttle butterfly 22 is closed, air can still reach the engine intake manifold through the valve 10, if the passage 12 is open. This happens if the driver takes his foot off the accelerator while the engine is running at speed.
The valve member 18 is connected to a
REFERENCES:
patent: 2443465 (1948-06-01), Leibing
patent: 4098850 (1978-07-01), Tamura
patent: 4122806 (1978-10-01), Bockelmann et al.
patent: 4194477 (1980-03-01), Sugiyama
patent: 4297984 (1981-11-01), Kawabata
patent: 4434778 (1984-03-01), Morita et al.
patent: 4494505 (1985-01-01), Naramura
Ford Motor Company
McCollum Robert E.
Miles Tim
Sadler Clifford L.
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