Abstract: A heat exchanger interposed between a supercharger of an internal combustion engine and an intake port of the internal combustion engine closes a space C between an outer periphery of stacked heat exchanger fins housed in a case having an intake inlet in communication with the supercharger and an outlet in communication with the intake port of the internal combustion engine and a case inner wall surface by a plate between the intake inlet and the outlet. The plate is an aluminum plate as a body that is different from the case. The outlet is provided with a net member for foreign matter passage prevention which is integrated with the plate.

Abstract: To provide an output power shaft structure for a personal watercraft which is superior in durability. A shaft of a propulsion device is connected to a rear end of a crankshaft of an engine, which is carried on a watercraft body such that the crankshaft thereof is directed in a longitudinal direction of the watercraft body, on an extension line of the crankshaft. A rear end of the crankshaft is disposed in an engine case, and an output power shaft separate from the crankshaft is connected to the rear end of the crankshaft. The shaft of the propulsion device is connected to a rear end of the output power shaft. The rear end of the crankshaft and a front end of the output power shaft are connected to each other in a transmission chamber in which a transmission mechanism for transmitting power of the crankshaft to a camshaft is provided at a rear portion of the crankshaft. A driving sprocket wheel of the transmission mechanism is provided on the output power shaft.

Abstract: A personal watercraft having an engine provided in a body formed from a hull and a deck, and a supercharger provided for the engine. An oil exit of the supercharger is disposed higher than an oil surface in the oil pan when the engine is not running. An oil tank is provided on an extension line of a crankshaft. A one-way valve is interposed in an oil returning passage, which communicates with the oil exit of the supercharger. This configuration minimizes oil residing in the supercharger when an engine is not running, and thus reduces the degradation of the entire oil supply for the engine and supercharger.

Abstract: An engine mount structure for a personal watercraft allows the engine to be incorporated in an inclined well-balanced state in the watercraft body having a hull and a deck, while making efficient use of the space within the body. The engine for driving a jet propulsion pump has an upper case and a lower case joined along a transverse plane parallel to the engine crankshaft and is mounted in the body so as to be inclined about the crankshaft, whereby an intake port side of the engine faces obliquely upwardly. Mounts on upwardly facing intake side of the engine are provided on the lower case, while mounts on the downwardly facing exhaust side are provided on the upper case. A starter motor is attached to the upwardly facing side of the engine.

Abstract: A mounting face of an oil pan is provided in the vicinity of the outside of a fastening bolt for fastening un upper case and a lower case of an engine that support a crankshaft when viewed from the bottom. A strainer is provided in the vicinity of the engaging surface between the oil pan and the engine along the engaging surface. An oil pump is provided at the end of the crankshaft. An oil exit in communication with the oil pump is provided on the oil pan at the end in the axial direction of the crankshaft and is brought into communication with the oil pump by the joint pipe. The aforementioned arrangement provides a dry-sump engine for a small planing boat that can reduce the overall height and size of the engine.

Abstract: To provide a supercharger cooling structure for a small watercraft which can sufficiently cool the supercharger. In a small watercraft in which an engine with a supercharger is incorporated, cooling water from a jet pump is supplied to the supercharger through a different supercharger cooling water passage independent of any other cooling water passage. The cooling water from the supercharger cooling water passage is first supplied to the supercharger to cool the supercharger and then supplied to an exhaust system provided on the downstream with respect to the supercharger in an exhaust system for the engine, whereafter it is discharged to the outside of the watercraft together with exhaust gas. Oil is supplied to the supercharger for lubrication of a bearing portion of the supercharger and is supplied to an oil jacket formed in a bearing casing to cool the bearing casing.

Abstract: An engine suitable for mounting in a small planing boat, which both lowers the center of the gravity of the boat, and enables a degree of freedom in arranging accessories. Balancers are arranged on the left and on the right of a crankshaft on a parting face of an engine. The engine is mounted in the body of the small planing boat surrounded by a hull and a deck. A starter motor and an idle gear of one balancer are arranged on the side opposite the starter motor, with the crankshaft between them. Also disposed between the idle gear and the starter motor is a cylinder. An oil tank is provided at the front of the engine, and two oil supply passages leading to the balancer supports are formed in the case of the oil tank.

Abstract: 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.

Abstract: A personal watercraft with an engine and a supercharger, in which a speedy, positive operation of the supercharger is ensured. The system includes an engine for driving a jet propelling pump provided in a watercraft body formed by a hull and a deck in such a manner as to extend in a length direction of the watercraft body. An oil pump is provided on the front side of the engine and a supercharger 140 is provided on the rear side of the engine. The supercharger and an end portion of a main gallery communicate with each other via an oil supply pipe. Oil supplied to the supercharger is used for lubricating a bearing portion of the supercharger. Further, the oil is supplied to an oil jacket formed in a bearing casing of the supercharger to cool the bearing casing. A one-way valve is interposed in an oil return pipe which communicates to an oil outlet of the supercharger.

Abstract: An oil jet device for piston cooling in which no press-fitting device is required, and the O-ring is prevented from being broken. A filter plug is inserted into an oil passage opening from the crank journal of a crankcase toward the side of the lower portion of the cylinder, and the crank journal is sealed by a plain bearing being abutted against the filter plug. The oil passage is formed by ring-shaped feed paths formed in the ring-shape on the bearing portions on the plain bearing and the crankcase.

Abstract: To provide a system for lubricating an engine for a personal watercraft, which is capable of simplifying an oil piping structure. An oil pump driven by a crankshaft of an engine and a relief valve for controlling a discharge pressure of the oil pump are provided in an oil tank provided on an extension of the crankshaft of the engine. Suction/discharge passages and the like for the oil pump are provided integrally with a tank main body. An oil filter in communication with the oil pump is provided in an upper portion of the oil tank, and communication passages for the oil filter are provided integrally with the oil tank. The oil filter is aligned with an opening of a deck. The tank main body covers drive chambers for accessories such as an ACG, a balancer shaft, and a starter motor of the engine.

Abstract: To augment the durability of a turbocharger. A hull and a deck of a personal watercraft are formed watertight and an opening of the deck is closed with a seat to form a body internal space. An intake duct for introducing atmospheric air from outside the body is provided in the space. An engine and a turbocharger connected to an exhaust manifold of the engine are provided in the space and the turbocharger is disposed higher than a body internal opening of the intake duct. A water jacket is formed in a casing of a turbine portion of the turbocharger and an oil jacket is formed in a bearing casing of the turbocharger, and cooling water is supplied to the water jacket and cooling oil is supplied to the oil jacket. The cooling water to the water jacket is supplied by a different turbocharger cooling water passage independent of any other cooling water passage.

Abstract: To utilize a small space in a vessel body efficiently and simultaneously augment the output power and realize a suitable water supply structure to an intercooler. A surge tank and an intercooler are provided between a supercharger and an internal combustion engine incorporated in the inside of a vessel body. The intercooler is disposed just below the surge tank, and an intake entrance from the supercharger and an exit to the surge tank are provided above the intercooler. A jet pump and the intercooler are in communication with each other directly by a cooling water hose, and cooling water is supplied from the intake entrance side into the intercooler.

Abstract: An ignition device for a personal watercraft engine, which allows mounting of a four-cycle engine on the personal watercraft and prevents occurrence of leakage of current. The engine for driving a jet propelling pump is provided in a watercraft body surrounded by a hull and a deck. A spark plug for spark ignition is provided in a cylinder head of the engine, and an integral cap ignition coil having a water-proof structure is water-tightly provided in the cylinder head in such a manner as to be located on the spark plug at an uppermost portion of the engine. A water-escape groove continuous to a recess for receiving a cap is formed in an upper surface of the cylinder head. A bottom surface of the escape groove is formed into a shape tilted downwardly.

Abstract: In order to provide an intercooler assuming a simple structure that enables cooling of supercharging air and absorption of any expansion/contraction of the cooling water pipe and the casing attributable to the heat of the supercharging air, intake/outlet pipes of a heat exchanger housed inside a cooling space formed within a case are inserted at cylindrical pipe insertion portions formed at the case, any gap present between the intake/outlet pipes and the insertion portions are sealed by seal members each constituted of an elastic material formed in a staged cylindrical shape having a first cylindrical portion placed in complete contact with one of the pipe insertion portions and a second cylindrical portion placed in complete contact with either one of the intake/outlet pipes, which are also utilized to fit the heat exchanger in the case with a gap.

Abstract: In order to suppress any backfire with a high degree of reliability and reduce the required mounting space and the weight of an intercooler by achieving a flame arrester function in the intercooler mounted to cool supercharging air without having to provide a separate arrester device, the intercooler having a case through which the supercharging air passes through and a heat exchanger 4 that is mounted inside the case and engages in heat exchange between the supercharging air and a cooling fluid includes a frame body 15 provided at the circumferential edges of air passage portions of the heat exchanger 4 on a supercharging air intake side and a supercharging air outlet side to reduce the gap between the heat exchanger and the inner wall of the case.

Abstract: An oil pump includes an oil supply pump and an oil recovery pump disposed on an extension line of a crankshaft of an engine. One joint member is provided at an end portion of the crankshaft, and another joint member is provided at an end portion of a pump shaft. The two joint members are coupled to each other on the same axial line within a front cover of an engine. The two joint members have alternating concave portions and convex portions. The convex portions of the two joint members include inclined faces and opposing driving transmission faces. The inclined faces of the convex portions guide the convex portions into the concave portion of the opposing joint member, so that the two joint members are meshed with one another. The crankshaft side joint member is fastened together with an ACG rotor. An oil tank connected to the oil pump is disposed above and very close to the oil pump.

Abstract: To provide a small-sized boat wherein a sufficient supercharging effect can be achieved. An engine having an exhaust manifold is disposed such that a crankshaft thereof extends in forward and rearward directions of a boat body, and an exhaust gas turbo charger which is driven to rotate by exhaust gas from the exhaust manifold is provided rearwardly of and adjacent to the exhaust manifold and rearwardly of and adjacent to the engine. The exhaust gas turbo charger is disposed such that a shaft which connects a turbine and a compressor is directed in leftward and rightward directions of the boat body, and the turbine is disposed adjacent to the exhaust manifold and the compressor is disposed adjacent to an intake port of the engine. An inter cooler is provided sidewardly of the compressor and disposed below an intake chamber.

Abstract: To make an intake apparatus and the inside of a boat body less likely to be contaminated with oil and to make an electric apparatus less likely to suffer from any trouble. A four-cycle engine having a head cover in which a breather exit is formed is carried in a boat body, and an oil storage portion when the boat is capsized is formed from the head cover. An upper face of the head cover is positioned close to and extends along a ceiling of the boat body, and the breather exit is provided above an upper face of oil stored in the head cover when the boat is capsized. A connection portion of the intake apparatus to a breather pipe is disposed below the breather exit. The head cover has a water drain path formed therein which connects to a plug mounting-dismounting hole and is opened to a peripheral face of the head cover rearwardly of the hole with respect to an advancing direction of the boat body. A water drain flow path is formed at a lowermost end portion of a bearing surface for a plug.

Abstract: To miniaturize an exhaust manifold to facilitate disposition of an engine in a boat body. A multiple cylinder engine having an exhaust manifold on a side portion thereof is disposed such that a crankshaft thereof extends along forward and rearward directions of a boat body. The exhaust manifold has a structure wherein exhaust pipes connected to exhaust ports of the engine are distributed upwardly and downwardly in such a manner as to form confluence pipes above and below the exhaust ports and the confluence pipes are further joined to each other to form an exhaust gas exit from the exhaust manifold. The exhaust gas exit is disposed at a substantially central portion of an internal space of the boat body in the vertical direction and an exhaust gas turbo charger is connected to the exhaust gas exit.