| 摘要 |
PURPOSE: To realize suitable control of an air/fuel ratio corresponding to a rotation frequency and a load by disposing a pressure regulator and an electromagnetic valve in a negative passageway of a diaphragm carburetor. CONSTITUTION: A housing 10 of a diaphragm carburetor is divided into a negative pressure chamber 17 and a fuel chamber 18 by a diaphragm 19. A negative pressure outlet 29 of a suction pipe negative pressure is connected to the negative pressure chamber 17 via a pipe 30 with a pressure regulator 31, an electromagnetic valve 32 and an equalization opening 33 disposed in the middle way thereof. In the pressure regulator 31, the negative pressure is defined to a suitably selected value based on the forces of a spring 38 and the diaphragm 36. The electromagnetic valve 32 controls the negative pressure acting on the negative pressure chamber 17 so as to attain a suitable air/fuel ratio to control a duty ratio of on/off function on the basis of a rotation frequency and a load.
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