Personal watercraft

A personal watercraft including a body including a hull and a deck covering the hull from above, an engine accommodated in an interior of the body, and an exhaust system that is accommodated in the interior of the body. The exhaust system includes an upstream muffler and a downstream muffler located on an upstream side and on a downstream side in a flow of the exhaust gas, the exhaust gas emitted from the engine flowing through the upstream and downstream mufflers, a first exhaust pipe through which the upstream and downstream mufflers communicate with each other, and a second exhaust pipe configured to extend from the downstream muffler outside the body. The upstream muffler and the downstream muffler are arranged in parallel, and the second exhaust pipe extends from the downstream muffler through a region that is located closer to the engine than the first exhaust pipe.

TECHNICAL FIELD

The present invention relates to a personal watercraft equipped with an engine and an exhaust system mounted in an interior of a body of the watercraft. More particularly, the present invention relates to a personal watercraft equipped with an exhaust system including mufflers arranged on right and left sides of the body.

BACKGROUND ART

A jet-propulsion personal watercraft for use in leisure, sport, etc., is equipped with an engine in an interior of a body including a hull and a deck covering the hull from above. An exhaust gas emitted from the engine is exhausted outside the body, through an exhaust system that is equipped behind the engine in the interior of the body and is configured to reduce the energy of the exhaust gas. As disclosed in Japanese Laid-Open Patent Application Publication No. 2004-98966 (in particular FIG. 3) and Japanese Laid-Open Patent Application Publication No. Hei. 9-236015, some personal watercraft include two mufflers arranged on right and left sides to accommodate an exhaust system in a limited inner space of a relatively small body.

In the exhaust system disclosed in Japanese Laid-Open Patent Application Publication No. 2004-98966, cylindrical mufflers each having closed both ends are positioned on an upstream side and on a downstream side in a flow of an exhaust gas and are arranged on right and left sides of the body. The exhaust gas emitted from an engine flows into the upstream muffler and then into a front portion of the downstream muffler through a first exhaust pipe extending from a rear portion of the upstream muffler. Further, the exhaust gas is discharged outside the body through a second exhaust pipe extending from a rear portion of the downstream muffler and through a region behind the first exhaust pipe. Thus, the exhaust system including the upstream muffler and the downstream muffler is efficiently disposed in the limited inner space of the body. In addition, the exhaust gas is repeatedly expanded and contracted while flowing through the upstream muffler, the first exhaust pipe, the downstream muffler, and the second exhaust pipe, in this order. As a result, the energy of the exhaust gas is efficiently reduced.

The center of gravity of a personal watercraft is a factor in determining a running characteristic of the personal watercraft, and therefore flexibility in positioning of the center of gravity is desirable. Because the center of gravity of the personal watercraft is substantially affected by the location of the engine, which is the component having the largest weight, there is a need for flexibility in the placement of the engine. Personal watercraft are typically equipped with an article accommodating compartment in a front part of the body. The engine is desirably positioned rearward rather than forward to increase a volume of the article accommodating portion.

SUMMARY OF THE INVENTION

The present invention addresses the above described conditions, and an object of the present invention is to provide a personal watercraft that is able to configure an exhaust system compactly by devising arrangement of components of the exhaust system, and is able to position an engine more flexibly.

According to the present invention, there is provided a personal watercraft comprising a body including a hull and a deck covering the hull from above, an engine accommodated in an interior of the body; and an exhaust system that is accommodated in the interior of the body and is configured to guide an exhaust gas emitted from the engine outside the body; wherein the exhaust system includes an upstream muffler and a downstream muffler located on an upstream side and on a downstream side in a flow of the exhaust gas, the exhaust gas emitted from the engine flowing through the upstream and downstream mufflers; a first exhaust pipe through which the upstream and downstream mufflers communicate with each other; and a second exhaust pipe configured to extend from the downstream muffler outside the body; and wherein the upstream muffler and the downstream muffler are arranged in parallel, and the second exhaust pipe extends from the downstream muffler through a region which is located closer to the engine than the first exhaust pipe.

Conventionally, the second exhaust pipe extends to be more distant from the engine than the first exhaust pipe. In contrast, in the exhaust system of the present invention, the upstream muffler and the downstream muffler are arranged in parallel, and the second exhaust pipe extends to be closer to the engine than the first exhaust pipe. Thereby, the exhaust system is compactly configured. As a result, sufficient space is provided to enable flexibility in positioning of the engine.

The exhaust system may be disposed behind the engine. The first exhaust pipe may be configured to couple a rear portion of the upstream muffler and a rear portion of the downstream muffler to each other, and the second exhaust pipe may extend from the downstream muffler at a location forward relative to a location where the first exhaust pipe is coupled to the downstream muffler. Thereby, the upstream muffler and the downstream muffler can be placed substantially at the same position in the longitudinal direction of the body of the watercraft. As a result, the exhaust system can be compactly configured, and the longitudinal dimension of the body can be made smaller.

The personal watercraft may further comprise a water jet pump that is disposed behind the engine and is configured to be driven by the engine. The water jet pump may be mounted between the upstream muffler and the downstream muffler, and the first exhaust pipe and the second exhaust pipe extend upward and are then curved above the water jet pump to extend downward. In such a configuration, the upstream muffler and the downstream muffler, each of which has a large volume, are mounted to efficiently utilize an inner space of the body. In addition, the shape of the first exhaust pipe and the second exhaust pipe makes it possible to inhibit water from flowing into the engine when the watercraft is inverted.

The hull may have a pump room for accommodating the water jet pump, the pump room being formed in a bottom surface of a center region in a width direction of the body at a rear end portion of the hull. The first exhaust pipe and the second exhaust pipe may extend through a region forward of the pump room. In such a configuration, since the first exhaust pipe and the second exhaust pipe are mounted to extend in a relatively wide space forward of the pump room, they can be easily assembled and disassembled, and the exhaust pipes can be simply configured.

The deck may include a flat rear deck provided at a rear portion thereof, and a protruding portion that is configured to protrude upward from the rear deck and to have an upper portion over which a straddle-type seat straddled by a rider is mounted. The first exhaust pipe and the second exhaust pipe may extend through an inner space of the protruding portion. In such a configuration, the first exhaust pipe and the second exhaust pipe can be easily assembled and disassembled. Because of the compact configuration of the exhaust system, the first exhaust pipe and the second exhaust pipe can be positioned relatively forward on the watercraft. In that case, the area of the flat rear deck is able to be increased.

The above and further objects and features of the invention will more fully be apparent from the detailed description with accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.FIG. 1is a side view showing an entire construction of a straddle-type personal watercraft according to an embodiment of the present invention.FIG. 2is a plan view of the personal watercraft ofFIG. 1. Turning now toFIGS. 1 and 2, a personal watercraft according to the embodiment has a body1including a hull2and a deck3covering the hull2from above. The hull2and the deck3are joined to each other over an entire periphery thereof by a gunnel line4. In this embodiment, the gunnel line4is located above a waterline L (indicated by a two-dotted line inFIG. 1) of the watercraft being at rest in the water and is substantially parallel to the waterline L.

A rear deck3A having a flat upper surface is formed at a rear portion of the deck3. Foot decks3B are located on right and left sides of the deck3to extend forward from the rear deck3A. The foot decks3B have flat upper surfaces. A protruding portion3C is formed at a center region in a width direction of the deck3and is located in front of the rear deck3A. The protruding portion3C is surrounded by the right and left foot decks3B. The protruding portion3C is configured to protrude upward from the rear deck3A and the foot decks3B. A deck opening3D is formed on an upper region of the protruding portion3C to allow the inside and outside of the body1to communicate with each other therethrough.

The deck opening3D, which has a substantially rectangular shape as seen from above, is formed at a location slightly rearward relative to a center of the deck3and at a center region in a width direction of the body1and is configured to extend in a longitudinal direction of the body1. A straddle seat7is removably mounted over the deck opening3D. An engine room6is provided in a space defined by the hull2and the deck3below the seat7. A four-cycle engine (hereinafter referred to as an engine) E is mounted within the engine room6. As used herein, the directions, namely, forward, rearward, leftward, rightward, upward and downward correspond with the directions seen from the perspective of a rider (not shown) straddling the seat7to steer the watercraft, except as where otherwise specifically described or illustrated.

As shown inFIG. 1, the engine E is mounted such that a crankshaft10extends rearward along the longitudinal direction of the body1. A rear end of the crankshaft10is integrally and rotatably coupled with a pump shaft12of a water jet pump P through a propeller shaft11. An impeller13is attached on the pump shaft12. The impeller13is covered with a cylindrical pump casing15on the outer periphery thereof.

A water intake16is provided on a bottom surface of the hull2. The water outside the watercraft is sucked from the water intake16and is fed to the water jet pump P through a water passage17. The water jet pump P pressurizes and accelerates the water by the impeller13and fairing vanes14guide water flow behind the impeller13. The water is ejected through a pump nozzle18having a cross-sectional area of flow that is gradually reduced rearward, and then from an outlet port19provided at a rear end thereof. As the resulting reaction, the watercraft obtains a propulsion force.

As shown inFIGS. 1 and 2, a bar-type steering handle20is coupled, through a cable (not shown), to a steering nozzle21mounted behind the pump nozzle18. The steering nozzle21is mounted to be pivotable rightward or leftward around a pivot shaft (not shown). The steering handle20operates in association with the steering nozzle21. When the rider rotates the handle20clockwise or counterclockwise, the steering nozzle21is pivoted in the opposite direction to enable the personal watercraft to be steered in a desired direction.

As shown inFIG. 1, a bowl-shaped reverse deflector23is mounted to an upper region of a rear side of the steering nozzle21so as to be pivotable downward around a pivot shaft24horizontally mounted. As shown inFIGS. 1 and 2, a reverse lever27is attached near the handle20, for example, at a location of the body1that is forward and rightward of the handle20. The reverse lever27is configured to be operated to allow switching between forward movement and rearward movement of the watercraft. A hatch cover28is openably mounted to a front portion of the deck3that is located forward of the handle20. An article accommodating compartment29having a predetermined volume is provided under the hatch cover28.

FIG. 3is a plan view showing an internal construction of the body1of the personal watercraft, the deck3of which is removed from the personal watercraft ofFIG. 2. Turning toFIG. 3, the protruding portion3C and the deck opening3D provided on the deck3are indicated by two-dotted line. As shown inFIG. 3, in the interior of the body1, the article accommodating compartment29, a fuel tank30, the engine E, an exhaust system40, and the water jet pump P are arranged in this order from forward. The article accommodating compartment29has a substantially rectangular shape in a plan view. The article accommodating compartment29is located at a front part in the interior of the body1. The fuel tank30is disposed near and behind the article accommodating compartment29and below the handle20(FIG. 1). The fuel tank30has a substantially rectangular shape in a plan view.

Right and left support portions2A are provided on right and left sides of the hull2and are located at a center region in the longitudinal direction of the body1to support the foot decks3B of the deck3from below. The right and left support portions2A have a rectangular shape that is elongated in the longitudinal direction of the body1in a plan view. In this embodiment, a longitudinal dimension of the support portions2A is smaller than one third of the longitudinal dimension of the body1. The support portions2A have flat upper surfaces which are in contact with lower surfaces of the foot decks3B, or are located in close proximity to, and under, the foot decks3B with the hull2and the deck3joined to each other.

The engine E is disposed behind the fuel tank30. The engine E is disposed between the right and left support portions2A provided on the hull2. The engine E includes an intake manifold32and an exhaust manifold33on a right side and a left side of an engine body31, respectively. The exhaust manifold33is configured to allow the exhaust gas from the cylinders of the engine E to be gathered and to be guided rearward. The water jet pump P is disposed behind the engine E to extend in the longitudinal direction of the body1. As shown inFIG. 3, a pump room15a, which is formed by a pump cover portion15bof the hull2, is located at a rear portion of the water passage17. The pump room15ais configured to accommodate the water jet pump P having a pump casing15which has an inner space that is connected to the water passage17. To be specific, the pump cover portion15bis located in a center region in a width direction of a rear end portion of the hull2. The pump cover portion15bprotrudes upward from the bottom surface of the hull2, i.e., inward of the body1in a rear view. As a result, the pump room15aprotrudes upward from the bottom surface of the hull2, i.e., inward of the body1in the rear view. The pump room15athat accommodates the water jet pump P is formed inward, i.e., below the pump cover portion15bto be connected to the water passage17.

The exhaust system40is disposed behind the engine E. The exhaust system40is coupled to the exhaust manifold33of the engine E, and includes an upstream muffler45, a downstream muffler46, etc. The exhaust system40is configured to guide the exhaust gas emitted from the engine E while reducing the energy of the exhaust gas to discharge the exhaust gas outside the body1through a rear portion of the body1.

FIG. 4is a partially enlarged plan view of the exhaust system40, showing a rear portion of the personal watercraft ofFIG. 3.FIG. 5is a partially enlarged side view of the body1taken along line V-V ofFIG. 4, a part of which is cut away, showing a construction of the exhaust system40accommodated in the interior of the body1.FIG. 6is a perspective view of the exhaust system40. InFIG. 4, the protruding portion3C and the deck opening3D are indicated by two-dotted lines. InFIG. 5, an outer shape of the body1is illustrated in simplified form.

As shown inFIG. 4, a muffler mounting base41is mounted in front of the pump casing15and is configured to cover the water passage17. The muffler mounting base41has a rectangular shape that is elongated in plan view and is configured to extend to the right and to the left of the water passage17. Right and left concave portions42that are recessed downward are formed on right and left regions of an upper portion of the muffler mounting base41. The upstream muffler45is stably placed in the left concave portion42and the downstream muffler46is stably placed in the right concave portion42. The upstream muffler45and the downstream muffler46are cylindrical and have closed end portions. The downstream muffler46is placed slightly behind the upstream muffler45, i.e., more distant from the engine E than the upstream muffler45. A battery47is placed on the muffler mounting base41between the upstream and downstream mufflers45and46.

Since the upstream muffler45and the downstream muffler46are arranged as described above in this embodiment, the dimension of the exhaust system40in the longitudinal direction of the body1is made smaller. The arrangement of the upstream and downstream mufflers45and46is achieved by the configurations of a first exhaust pipe51and a second exhaust pipe52as described below.

A pipe50extends forward from a front portion of the upstream muffler45, and a front end portion of the pipe50is coupled to a downstream end portion of the exhaust manifold33(seeFIG. 3) of the engine E. A first exhaust pipe51is mounted in front of the pump room15ato couple the upstream muffler45and the downstream muffler46to each other. An upstream end portion51aof the first exhaust pipe51is coupled to a rear portion of the upstream muffler45and a downstream end portion51bthereof is coupled to a rear portion of the downstream muffler46.

The first exhaust pipe51is substantially inverted-U shaped to extend over the water jet pump P. To be specific, the first exhaust pipe51extends rightward and upward from a location corresponding to the upstream end portion51acoupled to a peripheral wall of the rear portion of the upstream muffler45at a location slightly rightward relative to an uppermost portion of the upstream muffler45, i.e., closer to the center in the width direction of the body1, and then is curved above the water jet pump P to extend rightward and downward to a location corresponding to the downstream end portion51bcoupled to a peripheral wall of the rear portion of the downstream muffler46at a location slightly leftward relative to an uppermost portion of the downstream muffler46, i.e., closer to the center in the width direction of the body1.

A second exhaust pipe52extends from the downstream muffler46closer to the engine E than the first exhaust pipe51at a location that is forward relative to a location where the downstream end portion51bof the first exhaust pipe51is coupled to the downstream muffler46. The second exhaust pipe52extends to the left through a region that is located forward of the first exhaust pipe51and behind the battery47placed on the muffler mounting base41.

The second exhaust pipe52is substantially inverted-U shaped to extend over the water jet pump P (seeFIG. 6). To be specific, the second exhaust pipe52extends leftward and upward from a location corresponding to an upstream end portion52acoupled to a peripheral wall of a center region in the longitudinal direction of the downstream muffler46at a location slightly leftward relative to the uppermost portion of the downstream muffler46, and then is curved above the water jet pump P to extend leftward and downward to a location corresponding to a downstream end portion52bthat is configured to open in front of and near the upstream end portion51a. A pipe53is coupled to the downstream end portion52bof the second exhaust pipe52. The pipe53is curved at a location above the rear portion of the upstream muffler45to extend rearward through an outward side of the upstream end portion51aof the first exhaust pipe51and communicates with outside the body1at a rear wall (transom board) of the hull2.

In the exhaust system40constructed above, the exhaust gas emitted from the engine E (seeFIG. 3) flows into the upstream muffler45through the pipe50, and then into the downstream muffler46through the first exhaust pipe51. The exhaust gas outflows from the downstream muffler46and is thereafter discharged from the rear portion of the body1outside the body1through the second exhaust pipe52and the pipe53.

In the personal watercraft of this embodiment, as shown inFIG. 5, the rear deck3A is disposed near an upper surface of the pump cover portion15b, and the protruding portion3C is formed forward of the rear deck3A. The protruding portion3C has a tilted portion60extending forward and upward from a front portion of the rear deck3A in a side view. As shown inFIG. 4, the tilted portion60has a dimension in the width direction of the body1that increases forward. So, an inner space61of the tilted portion60has a height and a width that increase forward.

As shown inFIG. 5, upper portions of the first exhaust pipe51and the second exhaust pipe52respectively extend through the inner space61of the tilted portion60of the protruding portion3C. Because of the above mentioned structure of the inner space61, the inverted-U shape of the second exhaust pipe52has a curvature larger than that of the inverted-U shape of the first exhaust pipe51.

In the exhaust system40constructed above, since the first exhaust pipe51is mounted to extend between the rear portion of the upstream muffler45and the rear portion of the downstream muffler46and the second exhaust pipe52extends through the region that is located forward of the first exhaust pipe51, i.e., closer to the engine E, the longitudinal dimension of exhaust system40, including the upstream muffler52, the downstream muffler46, the first exhaust pipe51, and the second exhaust pipe52is made smaller. Because of the compact configuration of the exhaust system40, extra space in the interior of the body1is increased to enable the engine E to be positioned more flexibly. Since the engine E with a large weight is suitably placed, the center of gravity of the personal watercraft can be suitably located.

Because the first exhaust pipe51and the second exhaust pipe52extend through the inner space61of the tilted portion60of the protruding portion3C of the deck3, they are easily accessible through the deck opening3D for the purposes of assembly and disassembly. If the exhaust system40compactly configured is positioned relatively forward on the watercraft, then the first and second exhaust pipes51and52can be correspondingly positioned relatively forward on the watercraft, and therefore become more easily accessible through the deck opening3D. In this case, the protruding portion3C of the deck3can be placed relatively forward on the watercraft, or the tilted portion60of the protruding portion3C can be made to have a steep slope. As a result, the longitudinal dimension of the rear deck3A located rearward of the protruding portion3C can be increased.

If the exhaust system40compactly configured and the engine E are positioned relatively rearward on the watercraft, then a wide space is provided at the front part in the interior of the body1. In that case, a volume of the article accommodating compartment29or a volume of the fuel tank30can be increased.

Furthermore, since the first and second exhaust pipes51and52are substantially inverted-U shaped in the exhaust system40of this embodiment, water is less likely to flow into the engine E through the exhaust system40even when the watercraft is inverted.