Gas and liquid contact apparatus – Fluid distribution – Valved
Reexamination Certificate
2000-07-07
2002-05-28
Chiesa, Richard L. (Department: 1724)
Gas and liquid contact apparatus
Fluid distribution
Valved
C261S051000
Reexamination Certificate
active
06394426
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to engine fuel systems and more particularly to an apparatus providing a dual fuel supply to an engine.
BACKGROUND OF THE INVENTION
Typically, carburetors have been used to supply a fuel and air mixture to both four stroke and two stroke small internal combustion engines. For many applications where small two stroke engines are utilized, such as hand held power chainsaws, weed trimmers, leaf blowers, garden equipment and the like, carburetors with both a diaphragm fuel delivery pump and a fuel metering system have been utilized. In operation, two stroke engines utilizing these carburetors have a relatively high level of hydrocarbon exhaust emissions which are detrimental to the environment and exceed and cannot meet the exhaust emission requirements imposed by the State of California and the emission requirements proposed by the Environmental Protection Agency of the United States government and the governments of several other countries.
Due to the relatively low selling price of small two stroke engines, and particularly two stroke engines for hand held power tools and the like, it is not economically feasible to utilize sophisticated electronic fuel injection systems such as those typically used for automotive vehicle applications. Components such as sensors, high precision fuel injectors, electric fuel pumps, fuel pressure regulators, and electronic control modules are prohibitive in cost and render the engine and fuel system too large for the small engine industry. Some pneumatic assisted fuel injection systems have improved the exhaust emissions at relatively low cost for various small engines. However, they require a compatible non-electronic fuel metering system and pressurized fuel delivery system to support the engine fuel requirements over its wide range of operating loads and conditions as well as the environmental conditions in which the engines are used.
SUMMARY OF THE INVENTION
A dual supply apparatus with a fuel and air mixing passage through which a rich fuel and air mixture is provided to an engine to support the operation of the engine at idle and low speed, low load engine operation, and a pressurized fuel delivery passage providing a metered flow of fuel to a fuel injector downstream of the apparatus which provides the fuel required by the engine at high load, high speed and wide open throttle engine operating conditions. A shut-off valve closes to prevent the flow of fuel into the mixing passage when a throttle valve, which controls engine airflow operation, is opened a predetermined amount from idle to prevent the flow of the fuel into the mixing passage at high load and/or high speed engine operation. Similarly, a fuel injector circuit shut-off valve closes to prevent the flow of pressurized fuel to the fuel injector when the engine throttle valve is between idle and a predetermined position off of idle to prevent the flow of pressurized fuel to the fuel injector under low speed, low load engine operation.
Desirably, a camshaft rotates in response to rotation of the throttle valve to actuate both the mixing passage fuel shut-off valve and the fuel injector shut-off valve. This provides a mechanical synchronization of the switching of the fuel delivery from the mixing passage circuit to the fuel injector circuit in response to the throttle valve position. To provide a smoother switching of the fuel delivery between these circuits, preferably the opening and closing of both valves overlaps so they are both open at the same time so some fuel is supplied to the engine by both circuits during valve transition.
Objects, features and advantages of this invention include providing an apparatus which provides a fuel and air mixture to the engine crankcase under at least some operating conditions for lubrication of the engine and to support engine operation, provides a pressurized supply of fuel to a fuel injector apparatus under at least some engine operating conditions to enable the injection of fuel into the combustion chamber of the engine, reduces the hydrocarbon emissions of the engine, improves the fuel economy, permits use of a relatively inexpensive fuel injector mechanism, provides a desired fuel and air mixture to the engine under a wide range of engine operating conditions, does not significantly increase the total package envelope of the engine, minimizes the number of ancillary engine components required for control of fuel delivery, enables adjustment for the transition between crankcase fuel circuit operation and fuel injector circuit operation, is adaptable to a variety of engines, may be used with engines equipped with direct fuel injection technology, provides a low cost metered fuel supply to the engine, is of relatively simple design and economical manufacture and assembly, is reliable, durable and has a long, useful life in service.
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Galka William E.
Graham Joseph M.
Kueffner Anthony M.
Kuperus Peter P.
Roche Ronald H.
Chiesa Richard L.
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
Walbro Corporation
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