Hitachi Koki Co., Ltd.

Tanaka Kogyo Co., Ltd.

Nikko Tanaka Engineering Co., Ltd.

Shigetoshi Ishida

Shinki Ohtsu

Toshinori Yasutomi

Junichi Kamimura

Kohya Tanaka

Toshihide Sasaki

Fukushi Tamura

Akira Mezaki

Hiroshi Honzawa

Hiroki Nagase

Yasuhiro Sensui

Naoki Tsuruoka

Genji Akiba

A laminar-scavenging two-cycle engine which has a high laminar-scavenging effect, includes a scavenging passage having a crankcase side portion extending along a crankcase, and a cylinder side portion extending along a cylinder and having a length larger than the sum of the diameter and stroke of the cylinder. An ambient air introducing passage for introducing leading air into the scavenging passage is connected to an intermediate portion of the scavenging passage. A notch for opening a scavenging port to the side of the crankcase when a piston is near the top dead center is formed in the piston.

Stratified scavenging two-cycle engine

An engine is configured such that, during the starting of the engine, when it is being detected that throttle opening has been set at a starting position, if it is detected that the engine speed has exceeded a predetermined speed slightly lower than a speed when a centrifugal clutch becomes an engaged state, a control unit retards the ignition timing from a general angle to a first angle BTDC, and then advances the ignition timing to a second angle at predetermined intervals, and holds the ignition timing at the second angle for a predetermined time period, thereby preventing the engine from stopping due to fouling on the spark plug while suppressing the engine speed at the speed when the centrifugal clutch becomes the engaged state, or less.

Engine and engine-operated working machine

An engine-powered work tool includes an engine having a crank shaft, an ignition system, an output controller having a throttle valve shaft for controlling output of the engine, a wind governor connected to the throttle valve shaft, a rotation speed detector and an ignition control unit. The wind governor includes a governor plate movable upon receipt of cooling air generated by a cooling fan to control an angular rotation of the throttle valve shaft. The rotation speed detector detects a rotation speed of the crank shaft. The ignition control unit controls the ignition system based on the rotation speed of the crank shaft detected by the rotation speed detector to reduce the output of the engine when the rotation speed detector determines that the governor plate exceeds a predetermined position.

Engine-powered work tool provided with wind governor that performs ignition control

An engine includes: a carburetor configured to supply an air-fuel mixture of fuel and air; a crank case defining a crank chamber; a cylinder block which includes: a cylinder bore in which a reciprocable piston is disposed; and an intake port which supplies the air-fuel mixture supplied from the carburetor to the crank chamber; a control valve configured to open and close the intake port; and a controller configured to control the control valve. The controller controls the number of times that the control valve closes the intake port with respect to the number of times that the piston moves up to thereby reduce pressure of the crank chamber.

Small engine and engine work machine including the same

When throttle lever is pulled with the rotation lock member of the engine-powered tool in a state in which rotation of rear handle is permitted, the electrode terminal provided on the rotation lock member and the electrode terminal provided on throttle lever contact each other. As a result of this contact, the two output terminals of the engine generator are short-circuited, the supply of electric power to the ignition device from the engine generator is stopped and the supply of electric power from the ignition device to sparkplug in the engine is stopped. Through this, operation of the blade is prevented when rotating rear handle.

Hand-held engine-powered tool

The invention provides a two cycle engine which effectively suppresses an intrusion of a combustion gas into a crank chamber. Further, the invention provides a two cycle engine tool provided with the two cycle engine mentioned above. An engine is provided with a cylinder having two scavenge air ports at different positions in a cylinder circumference direction, and scavenge air inflow ports communicating individually with these two scavenge air ports via a scavenge air passage, and a piston in which two scavenge air communication ports are formed at positions corresponding to the scavenge air inflow ports, and is structured to swirl the gas flowing into the piston from the cylinder through the scavenge air passage, in an upper portion of the internal space of the piston, and retains the gas in the upper portion of the internal space of the piston.

Two cycle engine and two cycle engine tool

Provided is a laminar-scavenging two-cycle engine, which can have a higher laminar-scavenging effect than that of the laminar-scavenging two-cycle engine of the prior art and which can expect drastically excellent effects on the stabilization of combustion and on the blow-by prevention. The laminar-scavenging two-cycle engine is characterized in that a scavenging passage () is constituted to include a portion (or a crankcase side portion ()) extending along a crankcase () and a portion (or a cylinder side portion ()) extending along a cylinder () and to have a length larger than the sum of the diameter and stroke of the cylinder (), in that an ambient air introducing passage () for introducing the leading air into the scavenging passage () is connected to an intermediate portion of the scavenging passage (), and in that a notch () for opening a scavenging port () to the side of the crankcase () when a piston () is near the top dead center is formed in the piston ().

A stratified scavenging two-cycle engine that has a simpler structure than conventional stratified scavenging two-cycle engines and that has an excellent blow-by prevention effect etc. In an air intake stroke, lead air passes a lead-air port () etc. to flow into an inner space of a piston () during a period from the instant at which a lateral groove () starts to superpose on the lead-air port () until the superposing between the lateral groove () and the lead-air port () disappears after the piston () passes its top dead center. Further, in a scavenging stroke, lead air passes a scavenging path () etc. to flow into a cylinder () from a scavenging port () during a period from the instant at which a scavenging connection opening () and a scavenging inflow opening () start to superpose on each other until the superposing between the scavenging connection opening () and the scavenging inflow opening () disappears after the piston () passes its bottom dead center. Then, a mixture gas passes the inside of the piston () to flow into the cylinder () from the scavenging port ().

A two-cycle engine includes scavenging passages on the cylinder side and the crankcase side as the passages to supply scavenging gas into the cylinder. The passage on the cylinder side includes a passage inside the cylinder sidewall having substantially the same inner diameter as that of the opening area of the scavenging charge port, while the passage on the crankcase side includes a space between the inner peripheral surface at the top end of the crankcase and the outer peripheral surface of the piston, and a connection means provided between the top end of the space and the lower end of the scavenger passage of the cylinder. As the fuel mixture in the crank chamber flows into the scavenging passage on the cylinder side through the narrow space of the passage on the crankcase side and the connection means, the rapid inflow of the fuel mixture into the cylinder is restrained and the supply of the fuel mixture is sustained constantly high until the latter half of the scavenging time. This enables an optimum supply of fuel mixture, and radically decreases the amount of unburned gas in the fuel mixture that is emitted with the exhaust gas.

Two-cycle engine

A small engine suitable for hand-held work machines such as cleavers and chain-saws in which the engine is started by driving a self-starting motor with the electromotive force of a secondary battery and wherein the size and weight of the engine is reduced by eliminating the use of a generator since the secondary battery is charged by utilizing the electromotive force of a magnet in reverse direction that is not normally used for igniting the engine.

Small engine for hand-held work machines

A hand-held machine such as a cleaver or cutter having an engine as the driving source and wherein the drive shaft pipe is formed by telescopically extendable pipe members provided with a fixing means for fixing the pipe members relative to each other. The rotational force of the engine is transmitted to the cutter member via a first drive shaft having a circular section, at least one-way clutch and a second drive shaft on the side of the cutter member, to thereby minimize the size of the device for convenient transportation/storage, to improve the work efficiency, and to secure the safety of the operator.

Hand-held machine with power disengaging means

An ignition circuit for an internal combustion engine includes an ignition coil having a primary winding which is controlled by a power transistor. The lower transistor is controlled by either a first or a second control transistor. When the primary current flowing through the primary winding of the ignition coil is lower than a predetermined value, cut-off of the power transistor is controlled by the first control transistor. When the primary current is higher than the pre-determined value, cut-off of the power transistor is controlled by the second control transistor which becomes conductive prior to conduction of the first control transistor. Thus, two independent control means are alternately operated responsive to the primary current, which is a function of engine speed.

Growing community of inventors

Chiba, Japan

Shigetoshi Ishida