Walbro Japan, Inc.

Noriyu Nagata

An acceleration fuel pump for use with a combustion engine carburetor is an integral part of the carburetor body and provides an additional flow of fuel to the fuel-and-air mixing passage of the carburetor during acceleration of the engine. The acceleration fuel pump has a plunger which inserts sealably into a cylindrical cavity carried by the body of the carburetor. During acceleration of the engine, the plunger inserts further into the cavity against the resilient force of a spring and toward a resilient check valve member causing the member to deform into a fuel feed state. A fuel passage which extends between the bottom of a fuel chamber of the carburetor and the fuel-and-air mixing passage of the carburetor is intersected by the cavity and the resilient check valve member. The member has a slit at a leading portion of the member which opens when in the fuel feed state and fuel is pushed by the plunger out of a fuel reservoir carried by the cavity and into an outlet leg of the fuel feed passage which supplies fuel to the fuel-and air-mixing passage. During insertion of the plunger, pressure within the fuel reservoir overcomes the pressure within the fuel chamber causing a trailing segment of the member to expand radially outward and engage the internal cylindrical wall of the cavity preventing any reverse flow from the fuel reservoir and into an inlet leg of the fuel passage which extends from the cavity to the fuel chamber. When the engine is through acceleration, the plunger insertion stops and the internal spring forces the plunger retract in an outward direction from the cavity. This retraction causes a pressure reduction within the fuel reservoir causing the slit of the leading segment of the check valve member to close and the peripheral rim of the trailing segment to separate or space from the cylindrical wall of the cavity. Fuel is then drawn from the fuel chamber through the inlet leg of the fuel passage into the fuel reservoir in preparation for the next acceleration of the combustion engine.

Acceleration fuel pump having a resilient check valve member for a combustion engine carburetor

A rotary throttle valve type carburetor including an air intake passage extending through a carburetor body, a cylindrical valve chamber formed perpendicularly to the air intake passage, a throttle valve inserted into the valve chamber, and a throttle valve lever which rotates to impart rotation and axial movement to the throttle valve to thereby regulate the amount of air and fuel drawn through the carburetor. A plurality of circumferentially extending cam surfaces are formed on a bottom face of the throttle valve symmetrical with respect to the axis of the throttle valve, while tapered bores for receiving balls which are adapted to engage with the cam surfaces are formed in a bottom face of the valve chamber. The sliding engagement between the cam surfaces and balls due to rotation of the throttle valve is adapted to provide a predetermined axial movement of the throttle valve. Desirably, a columnar-shaped fitting jig is inserted into the valve chamber to press-fit the balls into the tapered bores so that the balls are disposed at a common height in the valve chamber.

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Miyagi-ken, Japan

Noriyu Nagata