Etg Limited

Mtd Southwest, Inc.

Ryobi Limited

Mitsubishi Jukogyo Kabushiki Kaisha

Hitachi Koki Co., Ltd.

Ryobi North America, Inc.

Ryobi Outdoor Products, Inc.

Katsumi Kurihara

Shiro Kawamoto

James M Grayson

Robert G Everts

Shigeo Yamamoto

Bin Guo

John E Nemazi

Takeshi Takeda

Takahiro Hirai

Takamoto Horiuchi

William G Conger

Hiroshi Ohira

Shohei Suzuki

Kojiro Kikuta

Teruaki Sasaki

There is provided a four-cycle engine which can appropriately circulate oil in an engine regardless of a tilted condition with a simple structure. A crankcase () of a four-cycle engine () has a crank room () which rotatably supports a crankshaft () and an oil room () which is provided adjacent to the exterior of the crank room (). The crankcase () also has partition walls () and () which partition the interior of the crankcase () into the crank room () and the oil room (), respectively, and a communication path () which communicates the crank room () with the oil room (). The partition walls () and () each has a cross section formed in a substantially V shape, and the communication path () is formed at an apex between the partition walls () and ().

Four-cycle engine, bush cutter and engine-driven tool having same

An engine lubrication method is provided. The four-cycle engine has an engine block having a cylindrical bore and an enclosed oil reservoir. A crankshaft is mounted in the engine block. An oil pump driven by the cam gear, brings the oil from the oil reservoir and the valve chamber. The engine is provided with a cylinder head assembly having a pair of overhead intake and exhaust valves. A circular arc wall surrounds the web of the crankshaft at a slight distance from the web. The crankshaft web causes the oil to fly to lubricate engine parts and the oil, returns into the oil reservoir by a check valve. Flowing of oil in to the combustion chamber when the engine is oriented to incline is prevented by oil recesses and long pipes. Another lubrication and breathing system without pump is presented, wherein construction except pump is basically followed.

Engine lubrication method

An engine lubrication and speed control method is provided. The four-cycle engine has a lightweight aluminum alloy engine block having a cylindrical bore and an oil reservoir formed therein. A vertical or horizontal crankshaft is rotatably mounted in the engine block for rotation about a crankshaft axis. A piston reciprocates within the bore and is connected to the crankshaft by a connecting rod. An oil pump is driven by the camshaft connected with a cam gear, which mates with a crank gear that is driven by the crankshaft, inhales the oil from the oil reservoir to splash lubricate into the cylinder bore and valve chamber. The engine is provided with a cylinder head assembly defining a compact combustion chamber having a pair of overhead intake and exhaust ports and cooperating intake and exhaust valves. A commonality of parts between the horizontal and the vertical engine is highly achieved.

Vertical and horizontal engine

An engine lubrication and speed control method is provided. The four-cycle engine has a lightweight aluminum alloy engine block having a cylindrical bore and an enclosed oil reservoir formed therein. A vertical or horizontal crankshaft is rotatably mounted in the engine block for rotation about a crankshaft axis. A piston reciprocates within the bore and is connected to the crankshaft by a connecting rod. A trochoid or screw oil pump is driven by the camshaft connected with a cam gear, which mates with a crank gear that is driven by the crankshaft, inhales the oil from the oil reservoir to splash lubricate into the cylinder bore and valve chamber. The engine is provided with a cylinder head assembly defining a compact combustion chamber having a pair of overhead intake and exhaust ports and cooperating intake and exhaust valves. A commonality of parts between the horizontal and the vertical engine is highly achieved.

A four-cycle engine with an enclosed oil reservoir for mounting on a power tool is provided. An oil pump driven by a camshaft, which mates by a cam gear with crank gear that is driven by a crank shaft, inhales the oil from the oil reservoir to lubricate the engine parts. A circular arc wall surrounds around web of the crankshaft with a slight distance from the web. A scroll-shaped wall has gradually increased distance from the circular arc wall to the direction of rotation of the web and has partial overlap with the circular arc wall. In case of stock of engine oriented power take off side up or down, oil is prevented to flow from oil reservoir to combustion chamber by a weir which is provided between the circular wall and the scrolled wall. The check valve splashes breathing missed oil from the crankshaft to the breather room and causes the oil to supply lubricant to lubricate the engine parts.

The present invention is directed to a four-cycle engine including a lightweight aluminum alloy engine block having a cylindrical bore and an oil reservoir formed therein. A crankshaft is rotatably mounted in the engine block for rotation about a crankshaft axis. A piston reciprocates within the bore and is connected to the crankshaft by a connecting rod. An oil pump driven by the cam gear, which mates with a crank gear that is driven by a crank shaft, inhales oil from the oil reservoir and the valve chamber to splash lubricate into the cylinder bore. The engine is provided with a cylinder head assembly defining a compact combustion chamber having a pair of overhead intake and exhaust ports and cooperating intake and exhaust valves and a circular arc wall which surrounds around webs of the crankshaft so that each crankshaft web splashes and causes the oil to fly to lubricate engine parts.

An engine lubrication method is provided. The four-cycle engine has a lightweight aluminum alloy engine block having a cylindrical bore and an enclosed oil reservoir formed therein. A crankshaft is rotatably mounted in the engine block for rotation about a crankshaft axis. A piston reciprocates within the bore and is connected to the crankshaft by a connecting rod. An oil pump driven by the cam gear, which mates with crank gear that is driven by crank shaft, inhales the oil from the oil reservoir to splash lubricate into the cylinder bore. The engine is provided with a cylinder head assembly defining a compact combustion chamber having a pair of overhead intake and exhaust ports and cooperating intake and exhaust valves. A lightweight, high-powered engine is thereby provided having relatively low HC and CO emissions. A circular arc wall surrounds around web of the crankshaft with a slight distance from the web. A scroll shaped wall has gradually increased distance from said wall to the direction of rotation of the web and has partial overlap with the circular arc wall. The crankshaft web splashes and flies the oil to lubricate engine parts and the oil after lubricating the parts is forced to return into the oil reservoir guided by scroll shaped wall.

A power tool having a rotary implement driven by a four-cycle engine. The engine crankcase is through a passageway which extends through a camshaft to a valve chamber. The rotating shaft member inhibits the escape of lubricating oil when the engine is running while permitting a lubricating oil mist to circulate through the engine.

Multi-position, operator-carried, four-cycle engine

An engine powered hand-held power tool and engine lubrication method is provided, the power tool being intended to be carried by an operator during use. The power tool has a frame, including a handle to be grasped by the operator, an implement affixed to the frame having a rotary input member, and a small four-cycle, lightweight, internal combustion engine attached to the frame for driving the implement. The four-cycle engine has a lightweight aluminum alloy engine block having a cylindrical bore and an enclosed oil reservoir formed therein. A crankshaft is rotatably mounted in the engine block for rotation about a crankshaft axis. A piston reciprocates within the bore and is connected to the crankshaft by a connecting rod. An oil splasher driven by the crankshaft intermittently engages the oil within the enclosed oil reservoir to splash-lubricate the engine. The engine is provided with a cylinder head assembly defining a compact combustion chamber having a pair of overhead intake and exhaust ports and cooperating intake and exhaust valves. A lightweight, high-powered engine is thereby provided having relatively low HC and CO emissions.

Operator carried power tool having a four-cycle engine and an engine lubrication method

Operator carried power tool having a four-cycle engine and engine lubrication method

A power tool having a rotary implement driven by a four-cycle engine. The engine crankcase is vented via an axial passageway which extends through at least one cam shaft axial shaft of the crankshaft and cam shaft. The rotating shaft member inhibits the escape of oil when the engine is running due to centrifugal force.

Multi-position operator-carried four-cycle engine

Operator carried power tool having a four-cycle engine and an engine

An internal combustion engine is provided with a cartridge containing a fuel/oil mixture where the fuel is liquid, normally gaseous fuel. The cartridges can be readily mounted or demounted from the engine, and provide flexibility of use coupled with easy starting. The use of the fuel/oil cartridges eliminates the need to separately mix oil and fuel, and eliminates substantial contact of the user with an oily fuel/oil mixture. The two cycle and four cycle cartridge-type engines are suitable for use in many hand-powered implements, including line trimmers, chain saws, leaf blowers, hedge trimmers, etc.

Growing community of inventors

Nagoya, Japan

Katsumi Kurihara