Yamabiko Corporation

Ken Shirai

Takahiro Yamazaki

Hisato Onodera

Koichirou Ogura

Hisato Osawa

Shirou Yamaguchi

Shiro Yamaguchi

Naoki Koga

Tetsuya Isogai

Yuji Numakunai

Daisuke Yamada

Shunsuke Ueda

Masaru Nozawa

Kenta Ito

Kazumichi Yamaguchi

A Schnuerle scavenging two-stroke engine is provided that can keep combustion stability in a wide rotation speed range while suppressing blow-by. The engine of the present invention is a Schnuerle scavenging two-stroke engine (). A scavenging passage ((in)) related to at least one scavenging port ((in)) has, at its upper end portion ((in)), an intake-side wall surface (). The intake-side wall surface () defines a first flow direction () of scavenging gas discharged from the scavenging port ((in)) at a height level of the scavenging port ((in)). The upper end portion ((in)) of the scavenging passage ((in)) related to the scavenging port ((in)) has a guide portion () defining a second flow direction () of scavenging gas discharged from the scavenging port ((in)). The second flow direction () is deflected to the intake side from the first flow direction () at the height level of the scavenging port ((in)).

Schnuerle scavenging two-stroke engine

Two-cycle engine includes cylinder block formed with a cylinder and crank chamber. The cylinder block includes: an exhaust passage leading to a combustion chamber in the cylinder through an exhaust port opened to an inner circumferential surface of the cylinder; a scavenging port opened to the inner circumferential surface of the cylinder; a communication passage extending from the scavenging port in a radial direction of the cylinder; and a scavenging passage extending in an axial direction of the cylinder, communicating with the crank chamber, and having an opening portion formed in a bottom surface of the communication passage. A ceiling surface of the communication passage is inclined toward a cylinder head with increasing distance from a scavenging passage side thereof toward the scavenging port. A bottom surface of the communication passage is inclined toward the crank chamber with increasing distance from a scavenging passage side thereof toward the scavenging port.

Two-cycle engine

Among multiple scavenging passagesincluded in a cylinder, a scavenging passage connected to at least one scavenging portconstitutes a variable scavenging passage(). An upper end portion of the variable scavenging passage() has a guide surfacedefining a discharge direction of a scavenging gas discharged from a variable scavenging port() connected thereto on a horizontal plane. The guide surfaceincludes at least a first guide portion(H) defining a first discharge direction of the scavenging gas and a second guide portion(L) defining a second discharge direction of the scavenging gas. The discharge direction of the scavenging gas is changed from the first discharge direction to the second discharge direction on the horizontal plane by the first and second guide portions(H) and(L) in the scavenging stroke.

Two-stroke internal combustion engine

Provided is a stratified scavenging engine and a portable work machine that suppress THC sufficiently. A stratified scavenging engine includes: a cylinder having a cylinder bore; and a piston stored in the cylinder bore to be movable in a reciprocating manner. The cylinder has an intake port to intake leading air and a scavenging port to scavenge combustion gas, the intake port and the scavenging port being open to the cylinder bore. The piston has a peripheral surface including a piston groove to guide leading air from the intake port to the scavenging port, and the piston groove has a recess near the intake port.

Stratified scavenging engine and portable work machine

An engine-driven working machine has an engine unit, a housing, and a vaned rotor. An air passage is defined between a crankcase of the engine unit and a bottom wall of the housing. The air passage has an inlet opening provided near an oil seal on a drive-side shaft, and an outlet opening provided in a magnet-side wall so as to face the vaned rotor. Rotations of the vaned rotor cause airflow from the inlet opening through the air passage to the outlet opening.

Engine driven working machine

An engine includes a cylinder block, and a piston slidably mounted in a cylinder, with the cylinder block being formed with an exhaust passage leading to a combustion chamber through an exhaust port, a first scavenging port opened to an inner circumferential surface of the cylinder, a first communication passage formed from the first scavenging port in a radial direction of the cylinder, and a first scavenging passage formed with an opening on a bottom surface of the first communication passage, in which a side surface on a far side from the exhaust port forming the communication passage is formed towards the far side from the exhaust port in the combustion chamber, and the opening portion of the first scavenging passage and a landing portion formed in the periphery of the opening portion are formed at a bottom portion of the communication passage.

The scavenging passage includes a wall surface that defines an orientation direction of a main scavenging gas flow spouting from the scavenging port to the cylinder chamber. In a boundary portion between the scavenging port and the scavenging passage, a wall surface located on an opposite side of the exhaust port is composed of an inclined surface inclined in a direction further away from the exhaust port than a wall surface of a deep portion of the scavenging passage. The scavenging port includes a rear wall surface located in a portion on the opposite side of the exhaust port. The rear wall surface continues to the inclined surface to extend in the direction away from the exhaust port and generates an incidental scavenging gas flow incidental to the main scavenging gas flow and higher in speed than the main scavenging gas flow.

The intake device for an engine includes a carburetor section and an air cleaner section. The carburetor section includes a body having an intake passage which has an opening communicating with the air cleaner section and a choke valve being a butterfly valve having a plate-like valve body. The air cleaner section includes an air filter, an air-flow chamber provided between the air filter and the intake passage, and a reverse-flow restriction surface provided within the air-flow chamber. The air cleaner section further includes a plate-like partition extending from a location near an air-cleaner side periphery of the valve body of the choke valve in the full-open position to a location near the reverse-flow restriction surface so as to continue the periphery.

Intake device for engine

There is provided an air cleaner that is capable of suppressing or reducing malfunctions and problems caused by mixed fuel that back flows from a carburetor, thereby prolonging filter life, reducing filter maintenance frequency, etc. The air cleaner comprises: a fuel accumulation part; and a back flow guide member that guides the mixed fuel that back flows into the air cleaner, wherein the plurality of return flow paths are provided in a radial fashion about the cleaner outlet.

Air cleaner

A filler member to be installed in a crankshaft including a crank web includes: an arm member, extending in a diametrical direction of a crank journal, and a weight member extending in a radial direction of the crank journal. The filler member includes: a fitting member, a connecting member mounted on the bodies. The fitting member is fixed to an outer side face of the crank web. The connecting member is mounted on the bodies to stride the arm member on inner side face of the crank web.

Filler member for crankshaft

A reverse scavenged two-stroke internal combustion engine is capable of effectively suppressing the short-circuiting of fresh charge (unburnt air-fuel mixture), while at the same time being capable of further improving scavenging efficiency, combustion efficiency, etc. The horizontal sectional shape of at least one pair of scavenging passages is closer to a triangle than a parallelogram along substantially the entire lengths of the at least one pair of scavenging passages, where a cylinder outer circumferential side of the horizontal sectional shape is narrowest and a cylinder bore wall surface side of the horizontal sectional shape is wide. Further, horizontal scavenging angles, which are angles of intersection formed between lines extended towards an intake port from guide wall surfaces that define the scavenging passages, are acute.

Growing community of inventors

Tokyo, Japan

Ken Shirai