Breather-operated priming system for small internal combustion engines

An internal combustion engine, comprising:

• a crankcase;
• a crankshaft, connecting rod, and piston assembly disposed within said crankcase, said piston reciprocable to generate pressure pulses within said crankcase at cranking and running speeds of said engine;
• a flywheel drivably coupled to said crankshaft;
• a carburetor including a fuel bowl;
• and
• a priming system, comprising:
• a control valve in fluid communication with said crankcase and said fuel bowl, said control valve including an air vane movable responsive to rotation of said flywheel, said air vane positioning said control valve at engine cranking speeds to direct at least a portion of the pressure pulses to said fuel bowl, and positioning said control valve at engine running speeds to divert at least a portion of the pressure pulses away from said fuel bowl.

An internal combustion engine, comprising:

• a crankcase;
• a crankshaft, connecting rod, and piston assembly disposed within said crankcase, said piston reciprocable to generate pressure pulses within said crankcase at cranking and running speeds of said engine;
• a carburetor including a fuel bowl;
• and
• a priming system, comprising:
• a control valve in fluid communication with said crankcase and said fuel bowl, said control valve movable responsive to cranking and running speeds of the engine, said control valve positioned in a first position at engine cranking speeds in which said control valve directs a substantial portion of the pressure pulses to said fuel bowl, and positioned in a second position at engine running speeds in which said control valve diverts a substantial portion of the pressure pulses away from said fuel bowl;
• and
• a vent valve in fluid communication with said control valve and said fuel bowl, said vent valve movable between a closed position at cold engine temperatures and an open position at warm engine temperatures, whereby in said closed position, a substantial portion of the pressure pulses pass from said control valve to said fuel bowl and in said open position, a substantial portion of the pressure pulses are vented to the atmosphere.

An internal combustion engine, comprising:

• a crankcase;
• a crankshaft, connecting rod, and piston assembly disposed within said crankcase, said piston reciprocable to generate pressure pulses within said crankcase at cranking and running speeds of said engine;
• a carburetor including a fuel bowl;
• and
• a priming system, comprising:
• engine-responsive means for directing a substantial portion of the pressure pulses to said fuel bowl at engine cranking speeds and for diverting a substantial portion of the pressure pulses away from said fuel bowl at engine running speeds;
• and
• temperature-responsive means for substantially disabling said priming system at warm engine temperatures.

A method of operating an internal combustion engine, comprising the steps of:

• starting the engine by cranking a crankshaft, connecting rod, and piston assembly to thereby generate pressure pulses within a crankcase of the engine;
• priming a carburetor of the engine by directing at least a portion of the pressure pulses to an internal chamber of the carburetor;
• automatically diverting at least a portion of the pressure pulses away from the internal chamber of the carburetor after the engine is started;
• and
• substantially disabling priming of the carburetor during subsequent re-starts of the engine.