Zama Japan Kabushiki Kaisha

Zama Japan

USA Zama, Inc.

Z Ama Japan Co., Ltd.

Mamoru Toda

Satoru Araki

Yuzuru Yanaka

Yoshiharu Iwasa

Koken Oyamada

Needle valve for carburetors

Socket wrench

An interlocking lever having first and second cam faces is mounted on a throttle valve stem, and a throttle valve is arbitrarily opened to perform start-up in a state in which the first cam face makes contact with the choke valve lever and the interlocking lever is stopped during low-temperature start-up with the choke valve closed. After the choke valve has been returned to the fully open position, the throttle valve alone is opened with a small degree of opening to perform low-load operation; and in the mid- and high-load region, the interlocking lever integrally turns with the throttle valve, the second cam face pushes the air valve lever, and the throttle valve and air valve are caused to open and close proportionally. Preferably, the degree of opening of the throttle valve for low load operation is adjustable.

Carburetor for two-cycle engine

The accelerator apparatus prevents air from remaining within a pump chamber and discharged fuel vapor from causing a pumping effect so as to a destabilize engine operation and increase of an exhaust gas content of harmful material, in an accelerator apparatus in which an accelerated fuel passage draws and discharges fuel to the pump chamber of an accelerator pump, which is connected to a main fuel passage. The pump chamber of the accelerator pump is mechanically coupled with a throttle valve and is connected to a fixed fuel chamber storing a fuel delivered to an intake passage at a fixed pressure by the accelerated fuel passage. Air remaining within the pump chamber and a fuel vapor generated within the pump chamber are discharged to the fixed fuel chamber, and fuel extruded from the pump chamber due to a pumping effect of the remaining air and the fuel vapor enters into the fixed fuel chamber, thereby preventing the alteration of a rate of the fuel flowing through a main fuel passage. Fuel in the pump chamber is fed to the fixed fuel chamber during acceleration so as to increase a pressure in the fixed fuel chamber, and an accelerated fuel is obtained by increasing the amount of the delivered fuel to the intake passage.

Accelerator apparatus for diaphragm carburetor

A starting apparatus of a diaphragm-type carburetor, a starting pump disposed at a convenient and accessible location which is separate from a carburetor main body, and air is prevented from being mixed into fuel, in such a structure constructed as a suction-type starting pump. A suction passage extends from a fuel metering chamber and extends beyond an outer portion of the carburetor main body. A starting pump conveniently disposed is separate from the carburetor, and an inlet check valve of the starting pump is disposed in the carburetor main body so as to reduce a volumetric capacity of a section extending to the inlet check valve from the fuel metering chamber, thereby preventing the air from remaining within the suction passage.

Starting apparatus of diaphragm-type carburetor

An interlocking lever having first and second cam faces is mounted on a throttle valve stem, and a throttle valve is arbitrarily opened to perform start-up in a state in which the first cam face makes contact with the choke valve lever and the interlocking lever is stopped during low-temperature start-up with the choke valve closed. After the choke valve has been returned to the fully open position, the throttle valve alone is opened with a small degree of opening to perform low-load operation; and in the mid- and high-load region, the interlocking lever integrally turns with the throttle valve, the second cam face pushes the air valve lever, and the throttle valve and air valve are caused to open and close proportionally.

An air-fuel ratio control system for a stratified scavenging two-cycle engine that facilitates the elimination of acceleration failure in the initial stage of acceleration due to the dilution of the air-fuel mixture when scavenging air is introduced. In a preferred embodiment, the control system includes a driving gear and a driven gear that are connected to a carburetor throttling valve for controlling output and an air valve for controlling the flow rate of the scavenging air, respectively. Improved acceleration is achieved by not increasing the amount of air relative to the increasing amount of air-fuel mixture initially being introduced by not engaging the gears until the throttling valve opens slightly from the idling position. When the throttling valve is wide open, the two gears engage with each other, thereby opening the air valve and maintaining a nearly constant flow rate ratio between the air-fuel mixture and the air. Alternatively, the control system may include a driving lever and a driven lever that are connected to a carburetor throttling valve and an air valve for controlling the flow rate of the air-fuel mixture and the scavenging air, respectively.

Air-fuel ratio control system for a stratified scavenging two-cycle engine

Methods of operating a diaphragm type carburetor to facilitate the atomization of fuel in the diaphragm-type carburetor are disclosed. Particularly, methods of operating a diaphragm-type carburetor having a check valve installed in a fuel passage leading from a constant-fuel chamber to a main nozzle, and an air bleed passage connected at a position on the downstream side of the check valve are disclosed. Moreover, techniques for operating a diaphragm-type carburetor having a main nozzle including nozzle openings facing downstream with respect to the engine intake air flow are also disclosed, wherein the nozzle openings are located in a tubular member cutting across a central axial line of the venturi so that the tubular member bridges the neck of the venturi.

Method of operating a diaphragm-type carburetor

The present invention serves to facilitate atomization of fuel in a diaphragm type carburetor for all-purpose two-cycle engines. A check valve used to prevent back flow is installed in the fuel passage leading from a constant-fuel chamber to a main nozzle, and an air bleed passage is connected at a position on the downstream side of the check valve. The main nozzle is constructed by forming nozzle openings which face downstream with respect to the engine intake air flow. The nozzle openings are located in a tubular member which cuts across a central axial line of the venturi so that the tubular member bridges the neck of the venturi.

Growing community of inventors

Iwate-ken, Japan

Mamoru Toda