Centrifugally operated evaporative emissions control valve system for internal combustion engines
View Patent ↗An evaporative emissions control system for small internal combustion engines. A control valve assembly includes a pair of control valves which are respectively associated with a fuel line and with a vent line which each connect the fuel tank and the carburetor of the engine. The control valve assembly is automatically operable responsive to the rotation of a rotatable member of the engine drive train, such as the crankshaft, camshaft, flywheel, governor assembly, or other rotatable member. In one embodiment, for example, the control valve assembly is driven from the flywheel. When the engine is not running, the flywheel is stationary and does not rotate, and the control valves automatically closes the vent line and the fuel line, thereby trapping fuel vapors within the fuel tank and blocking the supply of liquid fuel to the carburetor. Upon cranking of the engine for start up, a flyweight mechanism of the control valve is driven by rotation of the flywheel, and centrifugal force acting on the flyweight mechanism causes the control valve to automatically open the vent line and the fuel line, venting fuel vapors from the fuel tank through the vent line to the carburetor for consumption by the engine, and opening the supply of liquid fuel from the fuel tank to the carburetor.
1. An internal combustion engine, comprising:
a drive train including a rotatable member;
a carburetor;
a fuel tank; and
a control valve assembly in fluid communication with said fuel tank and with said carburetor, said control valve assembly including at least one valve member mechanically movable by said rotatable member between a first position when said rotatable member is stationary, in which said valve member prevents fluid communication between said fuel tank and said carburetor, and a second position upon rotation of said rotatable member, in which said valve member allows fluid communication between said fuel tank and said carburetor.
2. The engine of claim 1 , wherein said control valve assembly includes a flyweight mechanism in driven relationship with said rotatable member, said at least one valve member movably coupled to said flyweight mechanism.
3. The engine of claim 1 , further comprising a fuel line and a vent line each fluidly communicating said fuel tank and said carburetor, said control valve assembly in fluid communication with said fuel line and with said vent line.
4. The engine of claim 3 , wherein said control valve assembly further comprises:
a first valve member movable between said first and said second positions to prevent and to allow fluid communication between said fuel tank and said carburetor through said vent line; and
a second valve member movable between said first and said second positions to prevent and to allow fluid communication between said fuel tank and said carburetor through said fuel line.
5. The engine of claim 4 , wherein said control valve comprises a valve housing mounted to said engine, said valve housing including said first and second valve members.
6. The engine of claim 4 , wherein said valve members comprise spool valves mounted upon a common valve shaft, said valve shaft translatable by said flyweight mechanism between said first and said second positions.
7. The engine of claim 1 , wherein said drive train includes a crankshaft, and said rotatable member comprises a flywheel mounted to said crankshaft.
8. The engine of claim 7 , wherein said flywheel includes a first gear around a circumference thereof, and said control valve assembly includes a second gear in meshing engagement with said flywheel gear.
9. The engine of claim 8 , wherein said second gear includes a flyweight mechanism movably coupled to said at least one valve member.
10. An internal combustion engine, comprising:
a drive train including a rotatable member;
a carburetor;
a fuel tank; and
a control valve assembly in fluid communication with said fuel tank and with said carburetor, said control valve assembly comprising:
a flyweight mechanism in driven relationship with said rotatable member;
at least one valve member movable by said flyweight mechanism between a first position when said rotatable member is stationary, in which said valve member prevents fluid communication between said fuel tank and said carburetor, and a second position upon rotation of said rotatable member, in which said valve member allows fluid communication between said fuel tank and said carburetor.
11. The engine of claim 10 , wherein said drive train includes a crankshaft, and said rotatable member comprises a flywheel mounted to said crankshaft.
12. The engine of claim 11 , wherein said flywheel includes a first gear around a circumference thereof, and said control valve assembly includes a second gear in meshing engagement with said flywheel gear, said second gear including said flyweight mechanism.
13. The engine of claim 10 , further comprising a fuel line and a vent line each fluidly communicating said fuel tank and said carburetor, said control valve assembly in fluid communication with said fuel line and with said vent line.
14. The engine of claim 13 , wherein said control valve further comprises:
a first valve member movable between said first and said second positions to prevent and to allow fluid communication between said fuel tank and said carburetor through said vent line; and
a second valve member movable between said first and said second positions to prevent and to allow fluid communication between said fuel tank and said carburetor through said fuel line.
15. The engine of claim 14 , wherein said control valve comprises a valve housing mounted to said engine, said valve housing including said first and second valve members.
16. The engine of claim 14 , wherein said valve members comprise spool valves mounted upon a common valve shaft, said valve shaft translatable by said flyweight mechanism between said first and said second positions.
17. An internal combustion engine, comprising:
a drive train including a rotatable member;
a carburetor;
a fuel tank;
a fuel line and a vent line fluidly communicating said fuel tank and said carburetor; and
control valve means mechanically driven by said rotatable member for preventing flow of fuel and fuel vapors from said fuel tank to said carburetor through said fuel line and said vent line, respectively, when said rotatable member is stationary, and for allowing flow of fuel and fuel vapors from said fuel tank to said carburetor through said fuel line and said vent line, respectively, upon rotation of said rotatable member.
18. The engine of claim 17 , wherein said control valve means further comprises first and second valve members associated with said fuel line and said vent line, respectively.
19. The engine of claim 18 , wherein said control valve means further comprises flyweight means driven by said rotatable member for moving said first and second valve members.