| 摘要 |
<p>Disclosed herein is a spark advance control mechanism for an engine capable of being selectively operated on gaseous fuel and on liquid fuel, which mechanism comprises a carburetor including an air induction passage having a venturi, a movable throttle plate, and a port located in the induction passage between the venturi and the throttle plate, an intake manifold communicating between the air induction passage and the engine, a member electrically connected to the engine for timing of the sparking thereof and movable between a first position providing retarded sparking and a second position providing advanced sparking, a spring biasing the member toward said first position, a vacuum actuated motor operable to displace the member from the first position toward the second position in response to application to the vacuum motor of an increasing amount of vacuum, a vacuum chamber, a first conduit communicating between the fuel intake manifold and the vacuum chamber for providing a vacuum in the vacuum chamber in response to engine operation and including a check valve affording fluid flow from the vacuum chamber to the manifold and preventing fluid flow from the manifold to the vacuum chamber, a second conduit communicating between the vacuum chamber and the vacuum motor and including a first control valve movable between a normally closed position and an open position, a third conduit communicating between the port and the vacuum motor and including a second control valve movable between a normally open position and a closed position, and an operator control connected to the first and second control valves for opening the first control valve and closing said second control valve when the engine is operating on gaseous fuel, and for permitting closing of the first valve and opening of said second valve when the engine is operating on liquid fuel.</p> |
