USA Zama, Inc.

Z Ama Japan Co., Ltd.

Zama Japan Kabushiki Kaisha

Zama Japan

Kimio Koizumi

Satoru Araki

Yasuaki Kohira

The present invention provides an internal shape of a rotor for a two-bore rotary carburetor used in a stratified scavenging engine whereby an engine for a power saw, lawn mower, or the like can be stabilized in the course of a complete change in orientation during idling. A groove pocket () in communication with a fuel supply-side bore () is formed at the aperture edge of each of the upstream end and the downstream end of a carburetor rotor valve () toward an accelerated rotation direction in the fuel supply-side bore () of the rotor valve (). The groove pocket () is shaped so as to gradually rise and decrease in cross-sectional surface area toward the accelerated rotation direction along a peripheral surface of the rotor valve (). The resulting structure is one in which the groove pocket () is initially superposed with the mixing channel during horizontal rotation of the rotor valve (), the fuel supply-side bore () and the mixing channel are in communication with each other, and the fuel supply-side bore () opens before the air supply-side bore () does.

Internal shape of rotor for two-bore rotary carburetor used in stratified scavenging engine

A carburetor for a stratified scavenging two-cycle engine, in which a throttle valve and a air valve are formed in a valve element that is a single cylindrical member in which a throttle through-hole and an air through-hole are diametrically formed and which is rotatably fitted in a body, the mixture passage and the air passage being formed piercing through a body, wherein the height of the body is decreased so as to miniaturize the carburetor as a whole, and the mixture passage () and the air passage () are formed in a single cylindrical common hole () in which the mixture passage () and the air passage () are partitioned by a partition wall ().

Carburetor for stratified scavenging two-cycle engine

A carburetor for a stratified scavenging two-cycle engine, in which a throttle valve and an air valve are formed in a valve element that is a single cylinderical member in which a throttle through-hole and an air through-hole are diametrically formed and which is rotatably fitted in a body, the mixture passage and the air passage being formed piercing through a body, wherein the height of the body is decreased so as to miniaturize the carburetor as a whole, and the mixture passage () and the air passage () are formed in a single cylindrical common hole () in which the mixture passage () and the air passage () are partitioned by a partition wall ().

A choke valve is fixed to a predetermined position even after manual release, whereby an improved start and a subsequent stable operation are obtained. A fixing force and a valve opening force are applied to a choke valve shaft. Further, a pin of a choke valve lever pushes an arm piece of a throttle valve lever to slightly open a throttle valve when a choke valve is in a fully open position, and the choke valve opens half way to return the throttle valve to an idle position by a valve closing spring when a complete firing of the engine is achieved. When opening the throttle valve, a cam of the throttle valve lever pushes the pin to open the choke valve, a valve opening force overcomes a fixing force near the fully open position to set the choke valve to the fully open position, and the pin separates from the cam to open and close the throttle valve without interference with the choke valve. The fixing force overcomes the valve opening force from the fully close position to a position proximate to the fully open position, and the choke valve is fixed even after manual release.

Carburetor with manual choke mechanism

The present invention provides a carburetor that can be adapted to a variety of engines with different positional relationships between the location for feeding the air/fuel mixture and the location for feeding scavenging air. The carburetor a carburetor main body () with an air intake passage () forming a portion of the air/fuel mixture passage () and is provided with an air passage () that forms a portion of an air channel () for scavenging air. The air passage () is positioned parallel to an air intake passage (), and the front end thereof is positioned further to the base end side than to the engine-side front end face of the carburetor main body (), enhancing the degree of freedom for placing the conduit pipe () for connecting the air passage () to the scavenging air feed port (. Also, the throttle valve () and the air valve () are butterfly valves with mutually parallel valve stems, and the interlocking mechanism thereof has a simple configuration.

Carburetor for two-stroke engine

The object of the present invention is to easily provide an appropriate amount of starting fuel for all-purpose engines, without requiring any special skill. The upstream side and downstream side of a throttle valve in an air intake passage are connected by a bypass. This bypass and a constant-fuel chamber are connected by an increased-fuel passage which is equipped with a check valve. The system is arranged so that the bypass and increased-fuel passage are opened and closed more or less simultaneously by an opening-and-closing valve. The necessary amount of starting fuel can be supplied to the engine in a short time by means of the increased-fuel passage, so that starting can be accomplished by cranking the engine a few times. The flow of air into the constant-fuel chamber from the bypass is prevented by the check valve so that rough idling and the need to expel inflowing air are eliminated; and starting operations may be performed in any desired order.

Starting system for diaphragm carburetor

In a first aspect, a carburetor fuel adjusting device that facilitates control of the quantity of fuel that flows from the fuel chamber to an air intake port of a carburetor by making it possible for the user to adjust an adjustment valve within the limits defined by emission control regulations. The carburetor fuel adjusting device has a cap having two appendages, and an engagement area to engage a valve extension of the fuel adjustment valves of a carburetor. The cap is retained by the retainer in either a disengaged position, or an engaged position wherein the engagement area of the cap becomes attached to the valve extensions. In the engaged position, the adjustment valves can be turned in unison with the cap within a range formed by the angle between the appendages which, when rotated, abut against stoppers. In a second aspect, a retaining plate of elastic material having two retainer holes adapted to receive and retain the pair of adjustment valves in a prescribed adjustment position is laid against an outer surface of the carburetor body. The adjustment valves each have a base-end portion and a small diameter portion, the threads of the base-end portion having an external diameter larger than that of the threads of the small diameter portion. The external diameter of the threads of the base-end portion is also larger than the diameter of each of the retainer holes of the retaining plate such that when the adjustment valve is screwed into the screw hole of the carburetor, the base-end portion cuts threads in the retainer holes of the retaining plate to thereby prevent rotation of the adjustment valve.

Carburetor fuel adjusting device

A carburetor fuel adjusting device that facilitates control of the quantity of fuel that flows from the fuel chamber to an air intake port of a carburetor by making it possible for the user to adjust an adjustment valve within the limits defined by emission control regulations. The carburetor fuel adjusting device has a cap having two appendages to limit its turning in the lean mixture direction and in the rich mixture direction, and an engagement area to engage a valve extension of the fuel adjustment valves of a carburetor. The valve extensions are inserted through insertion holes of a retainer attached to the carburetor body. When the cap is retained by the retainer in a disengaged position, wherein the engagement area is not attached to the valve extensions of the fuel adjustment valves, the adjustment valves can be adjusted separately from the cap. The cap, however, can be moved forward to an engaged position wherein the engagement area of the cap becomes attached to the valve extensions. In the engaged position, the adjustment valves can be turned in unison with the cap within a range formed by the angle between the appendages which, when rotated, abut against stoppers.

Growing community of inventors

Kanagawa, Japan

Kimio Koizumi