Accelerator apparatus for diaphragm carburetor

Abstract

The accelerator apparatus prevents air from remaining within a pump chamber and discharged fuel vapor from causing a pumping effect so as to a destabilize engine operation and increase of an exhaust gas content of harmful material, in an accelerator apparatus in which an accelerated fuel passage draws and discharges fuel to the pump chamber of an accelerator pump, which is connected to a main fuel passage. The pump chamber of the accelerator pump is mechanically coupled with a throttle valve and is connected to a fixed fuel chamber storing a fuel delivered to an intake passage at a fixed pressure by the accelerated fuel passage. Air remaining within the pump chamber and a fuel vapor generated within the pump chamber are discharged to the fixed fuel chamber, and fuel extruded from the pump chamber due to a pumping effect of the remaining air and the fuel vapor enters into the fixed fuel chamber, thereby preventing the alteration of a rate of the fuel flowing through a main fuel passage. Fuel in the pump chamber is fed to the fixed fuel chamber during acceleration so as to increase a pressure in the fixed fuel chamber, and an accelerated fuel is obtained by increasing the amount of the delivered fuel to the intake passage.