The present nonprovisional application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-335611 filed on Oct. 31, 2001 the entire contents thereof is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a personal watercraft in which a saddle type seat is provided at approximately a central portion of a body, an engine is mounted under the seat with its axial line extending in the longitudinal direction of the body, and respective intake pipes communicate with a plurality of cylinders provided in the engine and extend from a side surface of the engine.
2. Description of Background Art
Personal watercrafts of this type have been known, for example, from Japanese Patent Laid-open No. Hei 8-48287 entitled xe2x80x9cPersonal Planing Watercraft.xe2x80x9d The personal watercraft will be hereinafter described in detail with reference to the FIG. 13 that corresponds to FIG. 1 of the above document. It is to be noted that parts of the personal watercraft in the following drawing are denoted by new reference numerals.
FIG. 13 is a sectional view of a related art personal watercraft. A personal watercraft 100 includes, at approximately a central portion of a deck 101, left and right side walls 102 and 103. A saddle-type seat 104 is provided on upper ends of the left and right side walls 102 and 103. An engine 105 is provided under the seat 104 with its axial line extending in the longitudinal direction of a body 106. Cylinders 105a . . . (symbol xe2x80x9c . . . xe2x80x9d indicates a plural number) in the engine 105 are tilted rightwardly, to largely expand a left side space 107 located on the left side of the engine 105. Intake system components 108 are provided in the left side space 107. With this configuration, the intake system components 108 can be prevented from protruding largely on the left side of a center 106a of the body 106.
By preventing the intake system components 108 from protruding largely on the left side of the center 106a of the body 106, a distance between the left and right side walls 102 and 103 on the deck 101 can be reduced in size. As a result, a driver can keep a natural posture when sitting astride the saddle-type seat 104 with his or her feet resting on foot-rest portions 101a. 
The intake system components 108 are mainly composed of air funnels 108a . . . , an intake silencer 108b, and an intake pipe 108c. The intake silencer 108b is in communication with the cylinders 105a . . . via the air funnels 108a . . . , and the intake pipe 108c is in communication with the intake silencer 108b. 
According to the intake system components 108, air sucked in the intake pipe 108c via an air suction port 108d of the intake pipe 108c is directed to the intake silencer 108b, and the air led in the intake silencer 108b is introduced into the cylinders 105a . . . via the air funnels 108a . . . 
According to this configuration of the related art personal watercraft, however, the intake pipe 108c extends rearwardly from a rear wall of the intake silencer 108b and also extends in the horizontal direction toward the center 106a of the body 106. A connection lower end 108e, at which the intake pipe 108c is connected to the rear wall of the intake silencer 108b is positioned over a bottom surface 108f of the intake silencer 108b. 
Accordingly, if sea water or other water penetrates into the intake silencer 108b, the water possibly remains in the intake system components 108, particularly, in the intake silencer 108b. 
An object of the present invention is to provide a personal watercraft capable of preventing sea water or other water from remaining in intake system components.
To solve the above-described problem, according to the present invention, there is provided a personal watercraft, in which a saddle-type seat is disposed at approximately a central portion of a body. An engine is mounted under the seat with an axial line of a crankshaft of the engine extending in the longitudinal direction of the body. A plurality of cylinders are provided in the engine that extend along the longitudinal direction of the body with respective intake pipes communicating with the cylinders extending from a side surface of the engine. An air box for containing the intake pipes is disposed in a space between the engine and a side wall. The personal watercraft includes the air box having at its portion in front of or behind the intake pipes, a swelled portion swelled inwardly of the body in the width direction; and an air suction port is formed in a lower portion of the swelled portion.
The air suction port is formed in the lower portion of the swelled portion of the air box. Accordingly, if sea water or other water penetrates into the air box, the water can be directed to the air suction port and be discharged outwardly from the air suction port. As a result, it is possible to prevent sea water or other water from remaining in the air box.
The air box has, at its portion in front of or behind the intake pipes, the swelled portion. In other words, the swelled portion can be disposed in front of or behind the engine. Accordingly, even if the swelled portion is swelled inwardly of the body in the width direction, it does not interfere with the engine. As a result, an outer side surface of the swelled portion can be made as close to the center side of the body as possible, so that the distance between the left and right side walls extending downwardly from the seat can be reduced in size.
According to the present invention, a bottom surface of the air box is tilted at a descending gradient toward the air suction port.
Since the bottom surface of the air box is tilted at a descending gradient toward the air suction port, if sea water or other water penetrates into the air box, the water can be efficiently directed along the descending gradient towards the air suction port and can be discharged from the air suction port. As a result, it is possible to prevent sea water or other water from remaining in the air box.
According to the present invention, an intake trap is disposed in the swelled portion at a position between the intake pipes and the air suction port.
Since the intake trap is provided between the intake pipes and the air suction port, even if dust is contained in air sucked from the air suction port, the dust can be removed by the intake trap. As a result, it is possible to supply clean air having been filtered by the intake trap via the intake pipes to the cylinders.
If a flame flows into the swelled portion side by a phenomenon such as back fire, the flow of the flame can be blocked by the intake trap.
According to the present invention, a breather pipe is mounted on the swelled portion via a breather trap.
Since the breather pipe is provided in the swelled portion via the breather trap, if a flame flows into the swelled portion side by a phenomenon such as back fire, the flow of the flame can be blocked by the breather trap.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.