Gas and liquid contact apparatus – Fluid distribution – Pumping
Patent
1997-04-18
1999-11-30
Chiesa, Richard L.
Gas and liquid contact apparatus
Fluid distribution
Pumping
261 391, 261 393, F02M 110
Patent
active
059928298
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The subject invention concerns a fuel-supply system for an internal combustion engine arranged in a suction channel leading to the engine body proper, said system comprising one or several air-regulating valves and one or several nozzles adjacent said valves.
BACKGROUND OF THE INVENTION
Carburettors for two-stroke or four-stroke engines are arranged in a suction channel leading to the engine body proper. Often, the carburettor has two air-regulating valves, viz. one throttle valve or air throttle and one choke valve. The throttle valve is used to control the throttle whereas the choke valve is used for cold starts. Usually, the choke valve closes entirely manually or automatically. A small opening in the choke valve ensures that only a minute amount of air flows past the valve upon starting attempts. As a result a very powerful negative pressure generates inside the suction channel adjacent the downstream nozzles. Consequently, a lot of fuel is supplied, giving a very rich air fuel mixture. This is necessary, since large quantities of fuel condensate on the walls of the suction channel, the crank case and the combustion chamber under these conditions. Carburettors do also exist that are equipped with one single air-regulating valve which in this case acts both as a throttle valve and a choke valve. Further, there are injection systems having a separate starting system including choke valves and starter nozzles that work in accordance with the carburettor principle. During start-ups the fuel amount is heavily influenced by the negative pressure from the choke valve.
It is characterstic of these kind of fuel supply system that during cold starts an air-regulating valve, usually designated choke valve, is almost fully closed whereby a heavy negative pressure is formed downstream of the air-regulating valve. Very often the valve is fully closed and a small opening ensures the required by-pass of a small amount of air. Obviously, it is also possible to use an end-position stop means for the air-regulating, valve whereby the latter will gape slightly open and no air opening is required. The size of the minute air opening is dimensioned to suit the lowest starting temperature at which the product usually is used. In the case of chainsaws this temperature could be e.g. -25.degree. C. This means that at higher temperature levels, for instance +20.degree. C., the air opening is too small to provide an accurate fuel-air mixture at start-ups. This gives an unnecessarily rich fuel mixture and complicates or prevents the starting function. In addition, the rich fuel mixture leads to unnecessary engine sooting and unnecessarily large exhaust emissions. For when the product is started the choke is turned to full open, since in reality it is hardly possible to "finely tune" the controls ensuring that the air opening coincides with the demand.
PURPOSE OF THE INVENTION
The purpose of the invention is to essentially reduce the above-outlined problems.
SUMMARY OF THE INVENTION
The above purpose is achieved by means of a fuel supply system in accordance with the invention having the characteristics appearing from the appended claims.
The fuel supply system in accordance with the invention thus is essentially characterized in that at least one cavity or channel is arranged in the wall of the suction channel and so positioned that when the air-regulating valve is in its closed position the cavity or channel will create a communication path from one side of the air-regulating valve to the opposite one, and in that an at least partly movable body, such as a plunger or a secured membrane, is positioned adjacent the cavity or channel in such a manner that it is able to affect the through-flow resistance in the communication path from one side of the air-regulating valve to the opposite one by forming a throttle in the communication path, and in that the position of the movable body, and thus the size of the throttling, is controlled by a temperature-responsive member, such as a bimetal element, whereby below
REFERENCES:
patent: 1133872 (1915-03-01), Maness
patent: 1968553 (1934-07-01), Heitger
patent: 2110211 (1938-03-01), Farrell
patent: 2868185 (1959-01-01), Bellicardi
patent: 3642256 (1972-02-01), Phelps
patent: 3836128 (1974-09-01), Lunsford
patent: 4770823 (1988-09-01), Sejimo
patent: 5200118 (1993-04-01), Hermle
Aktiebolaget Electrolux
Chiesa Richard L.
LandOfFree
Temperature compensated choke does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Temperature compensated choke, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature compensated choke will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1662368