Patent ID: 8261775
Filing Date: 2012-09-11
Classification: F02M,Y02T,Y10T

Abstract:
1. A scavenging valve assembly in a carburetor for an engine, the scavenging valve assembly comprising: a butterfly throttle valve opening and closing an air-fuel passage of the carburetor; and a rotary air valve for controlling airflow through an air scavenging passage of the carburetor, the rotary air valve having a cylindrical body with an air bore extending transversely therethrough and rotatable between an engine idle position in which the rotary air valve is not completely closed and a fully open position, a first cutout in a first open end of the air bore configured to communicate the air bore with only an upstream portion of the air scavenging passage when the rotary air valve is in its engine idle position and a second cutout in a downstream second open end of the air bore configured to communicate the air bore with only the downstream portion of the air scavenging passage when the rotary air valve is in its engine idle position so that the cutouts in conjunction with the air bore provide a continuous air flow path through the air scavenging passage from upstream of the cylindrical body through the first cutout into the air bore, through the air bore and from the air bore through the second cutout to downstream of the cylindrical body when the air valve is in its engine idle position, and, when the air valve begins to rotate from its engine idle position to its fully open position, the size of an opening area that airflow travels through the air bore continuously increases and airflow through the air bore continuously increases.