| 摘要 |
A method of reducing gaseous phase presence in the liquid fuel metering chamber of a diaphragm by providing a "High-Point Pick Up" hole positioned in the optimal metering chamber location (highest) to assure maximum purge evacuation of air and/or other gases prior to engine start-up and during running. This optimal location is dependent upon first determining, in advance of carburetor fuel feed circuitry and/or air purge system design, the orientation of the carburetor as mounted on the engine in its primary operator usage position, or so-called "standard operating position" (SOP). This SOP in turn is determined in the first instance by the engine manufacturer and/or the manufacturer of the portable engine-driven handheld appliance on which the engine is mounted. In one embodiment the two typical fluid circuits (air purge and normal idle/high speed fuel feed circuits) share a common, sole take-off inlet opening into the metering chamber, the same being located at the highest elevation point in the metering chamber in the given SOP orientation. This assures that the maximum amount of air and/or fuel vapor is removed from the metering chamber during purging prior to start-up and during running. In accordance with the invention, the primary usage position (SOP orientation) of the engine is determined and becomes a known use parameter prior to the carburetor manufacturer determining such take-off hole location. Both butterfly valve cubic carburetor and rotary valve carburetor embodiments are disclosed embodying the invention. <IMAGE> |
