Walbro Corporation

Walbro Japan, Inc.

Walbro Engine Management, L.l.c.

Jun Takano

Dairoku Suzuki

Takashi Horikawa

Teruhiko Tobinai

Takashi Abei

Tomoya Kawada

Naoya Kumagai

Katsuaki Hamataka

Kazuki Doi

Hitoshi Terakado

Yoshiaki Douyama

Shinichi Ohgane

Takeshi Sakaguchi

Toshimasa Takahashi

Tamio Aihara

Susumu Takezawa

Giovanni Vimercati

A charge forming device for a combustion engine includes a throttle body having a throttle bore, an air passage having at least a portion in which air flows separate from the throttle bore and a throttle valve with a valve head movable relative to the throttle body. A nozzle body has a fuel passage and a feed passage, the fuel passage is arranged to receive fuel that exits a fuel outlet of a fuel metering valve, and the fuel passage is communicated with a fuel chamber through which fluid flows into the throttle bore, and the feed passage is communicated with the air passage to receive air from the air passage and the feed passage is communicated with the fuel passage upstream of the fuel chamber, wherein air in the feed passage is mixed with fuel in the fuel passage upstream of the fuel chamber.

Fuel and air charge forming device

A throttle body has a throttle bore with an inlet, an outlet and an air passage. A throttle valve has a valve head received within the throttle bore. A fuel metering valve is mounted on the throttle body and has a valve element and a fuel outlet, the valve element is movable relative to a valve seat to control fuel flow through the fuel outlet. And the nozzle body is carried by the throttle body and has a fuel passage and a feed passage. The fuel passage is arranged to receive fuel that exits the fuel outlet, and is communicated with a fuel chamber through which fluid flows into the throttle bore. The feed passage is communicated with the air passage and with the fuel passage upstream of the fuel chamber. Air in the feed passage is mixed with fuel in the fuel passage upstream of the fuel chamber.

In at least some implementations, a fuel metering valve, includes a bobbin defining a passage and having one or more voids in the surface of the bobbin that defines the passage, aa wire coil around the bobbin and an armature. The armature is received within the passage in the bobbin and movable relative to the bobbin from a first position to a second position when electricity is supplied to the wire coil.

In at least some implementations, a charge forming device for a combustion engine includes a throttle body and a throttle valve. The throttle body has a throttle bore with an inlet through which air flows into the throttle bore and an outlet from which a fuel and air mixture exits the throttle bore. The throttle bore has a throat between the inlet and outlet and the throat has a reduced flow area compared to at least one of the inlet and outlet. The throttle valve has a valve head received within the throat of the throttle bore and movable relative to the throttle body between a first position and a second position wherein the flow area between the valve head and the throttle body is greater when the valve head is in the second position than in the first position.

A carburetor includes a main body defining a bore, a main passage and a venturi defined within the bore, and a fuel nozzle carried by the main body and including a fuel nozzle outlet communicating with the venturi. The carburetor may also include a valve member translatable across an axis of the bore, such that in a closed state, the valve member closes the main passage but maintains the venturi at least partially open. The carburetor may also include a needle valve disposed at an end of the fuel nozzle substantially opposite of the fuel nozzle outlet to variably control flow of fuel into a fuel nozzle inlet, and a needle valve transmission may be coupled between a throttle shaft and the needle valve to convert rotation of the throttle shaft to translation of the needle valve.

Variable venturi carburetor

A rotary throttle valve carburetor includes a main body defining a mixing passage and a valve bore, and a throttle valve rotatably received in the valve bore to selectively open and close the mixing passage. The carburetor main body includes an integral throttle valve support extending radially inwardly relative to the valve bore adjacent to a first end of the valve bore and a second end of the valve bore is open. A throttle cable retaining portion may also be integrally formed with the carburetor main body.

Rotary throttle valve carburetor

A compact engine start device of a combustion engine rotary-type carburetor overrides normal operation of a rotary throttle valve to provide a richer mixture of fuel-and-air to start a cold engine. Rotation of a start lever of the start device activates a releasable camming interface coupler causing the throttle lever to rotate about a rotary axis and axially lift partially out of the carburetor at prescribed angular and axial distances. This provides the engine, through a fuel-and-air mixing passage, with a controlled and enriched ratio and volume of a fuel-and-air mixture. Preferably, the start lever has a projecting rod that inserts into a hole in the carburetor body for rotation about an axis orientated substantially parallel to the rotary axis. An outward surface of the start lever is in rotational sliding contact with a low-profile, preferably cantilevered, retention arm preferably formed unitarily to a metering fuel pump cover engaged removably to the body of the carburetor, thus allowing rotational movement but preventing axial movement of the start lever. Because the start lever does not move axially to displace the rotary throttle valve, the height of the start lever is favorably minimized. Moreover, the start lever preferably has a knob for user interface at a distal end of the lever that conforms generally about the retention arm thus maximizing knob size yet not contributing to an increase in carburetor size.

Engine start device of a rotary valve carburetor

A rotary throttle valve carburetor includes a body having a fuel and air mixing passage and a throttle valve movable between idle and wide open positions. A valve bore is increasingly aligned with the fuel and air mixing passage as the throttle valve is moved from idle toward its wide open position. A fuel metering needle is responsive to movement of the throttle valve so that the needle moves relative to the body in response to movement of the throttle valve. A fuel nozzle extends into the valve bore, is associated with the fuel metering needle, and has a fuel ejection passage with an effective flow area controlled by movement of the fuel metering needle relative to the fuel nozzle and includes a portion with a cross-sectional area that gradually increases in the direction of fuel metering needle movement corresponding to throttle valve movement toward its wide open position.

A variable venturi carburetor for a combustion engine has an uprighted cup-shaped piston head which forms an integral part of a venturi within a fuel-and-air mixing passage carried by a carburetor body, and a needle that projects rigidly downward from the head into a fuel feed passage. The position of the piston head controls air flow by adjusting the air flow cross-section of the variable venturi, and the needle simultaneously controls fuel flow into the fuel-and-air mixing passage at the venturi via obstruction of the fuel feed passage. The piston head and needle move in unison by a flexible diaphragm engaged to and disposed above the head. An atmospheric chamber is defined below the diaphragm and a vacuum chamber is defined generally above the diaphragm. A vacuum passage extends through the bottom of the head communicating between the fuel-and-air mixing passage at the venturi and the vacuum chamber. As vacuum at the venturi increases, the volume of the vacuum chamber decreases and the flexing diaphragm moves the head partially out of the fuel-and-air mixing passage until a balance of forces between the vacuum draw and the resilient compression of a spring disposed within the vacuum chamber and which biases the head into the passage is reached. During cold engine starts, cold idling, and cold acceleration, a cold engine priming device sensing the temperature of the engine and delivers additional fuel into the fuel-and-air mixing passage from a fuel chamber when the engine is below a pre-set value.

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Miyagi-Pref., Japan

Jun Takano