Honda Giken Kogyo Kabushiki Kaisha

Takaharu Kurosaki

Yuji Tsushima

Yoshitsugu Gokan

Takeshi Wakabayashi

Masahiro Asai

Kenichi Noda

Yoichi Ishibashi

Kenjiro Saito

Ryutaro Yamazaki

Masashi Amano

Masami Takubo

Takahiro Kimijima

Yoichi Ishibasi

To provide an output shaft structure of a personal watercraft, which is capable of enhancing the durability of the engine. An engine is mounted on a watercraft body with a crankshaft extending in the longitudinal direction of the watercraft body. A shaft of a propulsion device is coupled to a rear end of the crankshaft in such a manner as to be disposed on an extension of the crankshaft. The crankshaft is supported by an engine case via plain metal. An output shaft is provided separately from the crankshaft and is coupled to the rear end of the crankshaft. The shaft of the propulsion device is coupled to the rear end of the output shaft. The output shaft is supported by the engine case via rolling bearings immovable in a thrust direction. A spline is formed on or in each of the rear end of the crankshaft and the front end of the output shaft, and a spline to be engaged with these splines is formed in or on an inner surface of a connection pipe. The rear end of the crankshaft is coupled to the front end of the output shaft via the connection pipe. A gap is formed between opposed faces of the rear end of the crankshaft and the front end of the output shaft.

Output shaft structure of personal watercraft

The expected performance of a jet-propelled boat is maintained, exhaust control valves are controlled and driven in an improved accuracy on the basis of the traveling speed of the jet-propelled boat. Thus, the fuel consumption is improved and the exhaust gas is purified. A two-stroke cycle engine drives a jet propulsion unit to make the jet propulsion unit suck in water and jet water therefrom to propel a hull of the boat. An exhaust control valve is disposed near the exhaust port of the engine to change the opening ratio of the exhaust port according to the operating condition of the engine. A driving mechanism for driving the exhaust control valve includes a hydraulic actuator. The power of water jetted by the jet propulsion unit represents the traveling speed of the jet-propelled boat accurately. The exhaust control valve is driven for opening and closing according to the pressure of water jetted by the jet propulsion unit to achieve the optimum exhaust control by the exhaust control valve without entailing an excessive increase in the output of the engine.

Jet-propelled boat

To provide a structure for attaching exhaust control valves near exhaust ports in a two-cycle engine, the exhaust control valves variably controlling open areas of the exhaust ports. The cavity for receiving the exhaust control valves is formed near the upper edges of the exhaust ports on the cylinder block. The holder member is interposed between the cylinder block and the exhaust manifold, is attached to the pivot for supporting the exhaust control valves. A flange is provided for connection with the cylinder block. Therefore, the exhaust control valves are disposed near the upper edges of the exhaust ports. It is not necessary to form bearings on the cylinder block using a complicated process. Complicated parts such as bearings are collectively formed on the holder member that is independent and compact and easily machined. The pivot extends across the exhaust passages that are formed downwardly in order to detour around the pivot. A jet-propelled boat is provided with a saddle seat in which the power unit is neatly and compactly arranged in a limited space.

Two-cycle engine

A method of lubricating a two-cycle internal combustion engine, which is capable of preventing blow-by of an air-fuel mixture in a combustion chamber, is provided for increasing fuel consumption and purifying exhaust gas. Lubrication of a valve portion and a sliding portion of a cylinder bore to a piston is improved so as to enhance maintenance performance and further improve fuel consumption. The method for lubricating a two-cycle internal combustion engine in which a control valve is disposed, in communicating passages for communicating a combustion chamber to a chamber portion adjacent to the combustion chamber, wherein the oil is supplied to bearing portions of the control valve for lubricating the bearing portions, and also the oil permeates through the communicating passages to be supplied to a sliding portion of a cylinder bore to a piston by an injection flow of the fuel or the air-fuel mixture, and lubricates the sliding portion.

Method for lubricating a two-cycle internal combustion engine

A two-cycle engine of the spark ignition type is provided wherein a mixture in a combustion chamber can be compressed and self-ignited at least in a low load operation region to effect an activated heat atmosphere combustion. In a transition operation region between the activated heat atmosphere combustion region and an ordinary spark ignition combustion operation region, the mixture can be ignited by a spark ignition at a timing earlier than the spark ignition timing in the ordinary spark ignition combustion operation region to stabilize the combustion condition and eliminate abnormal combustion noise and the harmful effects of heat. A throttle valve opening of a throttle valve manually operated is detected by a throttle valve opening sensor formed from a potentiometer or the like while an engine speed is detected by an engine speed sensor, and they are inputted to a CPU. The CPU operates in accordance with a control graph of FIG. 5 which defines an exhaust air passage opening ratio in response to the engine speed Ne and the throttle valve opening, and transmits to an exhaust control servomotor a drive signal at which the exhaust air passage opening ratio based on the graph is provided. An ignition plug 22 generates, in an ordinary combustion operation region, a spark at 10.degree. (crank angle) prior to the top dead center. When it is discriminated by the CPU that the engine is operating in a transition operation region A between the ordinary combustion operation region and an AR combustion operation region, a spark is generated at 20.degree. prior to the top dead center in response to a control signal of the CPU.

Two-cycle engine of the spark ignition type

A combustion controller for an internal combustion spark ignition type two-cycle engine includes exhaust passage opening ratio adjusting means for adjusting an exhaust passage opening ratio, wherein the exhaust passage opening ratio adjusting means is driven to adjust the exhaust passage opening ratio at a value corresponding to an engine speed and a throttle valve opening ratio at least in a low load operational area. And fresh mixture in a combustion engine is self-fired with a firing timing desirable for operation of the engine. In this engine, the combustion controller includes ignition timing adjusting means for adjusting an ignition timing; abnormal combustion detecting means for detecting abnormal combustion in the combustion chamber; and control means for controlling the exhaust passage opening ratio. The ignition timing at respective values eliminates the abnormal combustion on the basis of the detection signal from the abnormal combustion detecting means.

Growing community of inventors

Saitama, Japan

Takaharu Kurosaki