| 摘要 |
A carburetor having a fuel pump, a fuel metering diaphragm defining a fuel chamber on one side of the diaphragm and an air chamber on the opposite side of the diaphragm vented to the atmosphere, and a second diaphragm defining a first chamber on one side of the second diaphragm in communication with the carburetor fuel pump and a valve actuated by the second diaphragm to control the application of engine crankcase pressure pulses to the fuel metering diaphragm in response to the pressure at the carburetor fuel pump. The second diaphragm is yieldably biased to position the valve in a first position and upon cranking for initially starting the engine, pressure pulses from the engine crankcase are communicated to the air chamber of the fuel metering diaphragm. The pressure pulses from the engine crankcase act on the fuel metering diaphragm causing it to fluctuate and thereby increase the quantity of fuel mixed with the air flowing through the carburetor to facilitate staring the engine. After the engine is started and is running, the carburetor fuel pump output pressure increases and acts on the second diaphragm from within the first chamber to displace it and move the valve to its second position to prevent the pressure pulses from the engine crankcase from materially affecting the fuel metering diaphragm to permit conventional operation of the carburetor. |
