Walbro Japan, Inc.

Masao Suzuki

Takashi Abei

Tetsuji Kojima

Hiroshi Nagata

Hidenori Sasaki

A stratified scavenging carburetor with a lost motion coupling permits limited relative movement of a throttle valve relative to an air valve so that initial opening of the throttle valve off idle does not open the air valve to avoid diluting with scavenging air the fuel and air mixture delivered to an engine. Rotation of the throttle valve beyond a predetermined amount from idle causes a corresponding opening of the air valve to provide scavenging air to the engine. Closing a choke valve engages a lock lever with the throttle valve to move the throttle valve off idle to a start position without opening the air valve. In another embodiment, closing the choke valve prevents the air valve from opening even if the throttle valve is moved beyond where the throttle valve would cause the air valve to open if the choke valve were open. Thus, a richer than normal fuel and air mixture can be supplied to the engine during a choke-assisted start and warm-up of the engine.

Stratified scavenging carburetor

An idle fuel supply device for a carburetor has an idle air passage that communicates with an air intake passage and a fuel chamber. A passage extending from a fuel metering chamber is connected to the fuel chamber preferably via a fuel adjusting needle valve. A low speed fuel nozzle hole communicates the fuel chamber with the air intake passage in the vicinity of a throttle valve when in its idle position. A passage communicates with the fuel chamber and the idle air passage, so that fuel and air may mix in at least a portion of the idle air passage.

Carburetor with idle fuel supply arrangement

A diaphragm-type carburetor has a body defining at least in part an air intake passage, a fuel metering chamber that receives fuel for delivery into the air intake passage, a fuel supply passage communicating a supply of fuel with the fuel metering chamber, and a bypass passage communicating the fuel supply passage with the air intake passage to facilitate removal of air and fuel vapor from the carburetor. The bypass passage is routed around, and does not communicate directly with the fuel metering chamber. Fuel vapor or air in the carburetor is quickly led from the bypass passage to the air intake passage to prevent a large quantity or volume of fuel vapor or air from staying in or flowing to the fuel metering chamber and thereby adversely affecting the operation of the carburetor.

Diaphragm-type carburetor

A membrane fuel pump (A) is driven by the pulsating pressure of intake air of an engine. Fuel in the fuel tank ( ) is supplied to a constant-pressure fuel chamber ( ) through valve ( ), and further to an intake passage through a fuel nozzle ( ). A membrane purge pump (B) is also driven by the pulsating pressure of the intake air of the engine. A plurality of vapor reservoir chambers ( ) are provided in a ceiling of the fuel chamber ( ). The fuel vapor in the vapor reservoirs ( ) is discharged from the fuel chamber ( ) and back into the fuel tank ( ) by the membrane purge pump (B).

Growing community of inventors

Miyagi-ken, Japan

Masao Suzuki