Jet propelled watercraft and jet propulsion assembly

A jet propelled watercraft includes a first exhaust pipe connected to an exhaust port, a catalyst storage connected to the first exhaust pipe, a second exhaust pipe connected to the catalyst storage, and a water lock connected to the second exhaust pipe. The catalyst storage and the water lock are located outward in a width direction with respect to the exhaust port of the engine in a plan view of the jet propelled watercraft.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Patent Application No. 2016-120642 filed in Japan on Jun. 17, 2016, the entire contents of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a jet propelled watercraft and a jet propulsion assembly, and more particularly, it relates to a jet propelled watercraft and a jet propulsion assembly each including a water lock.

2. Description of the Related Art

A jet propelled watercraft including a water lock is known in general. Such a jet propelled watercraft including a water lock is disclosed in Japanese Patent Laid-Open No. 11-245895, for example.

Japanese Patent Laid-Open No. 11-245895 discloses a small watercraft (jet propelled watercraft) including an engine, a catalyst, and a water lock. In this small watercraft, exhaust gas discharged from the engine is guided to the water lock through the catalyst. In this small watercraft, the catalyst is located on a first side in a width direction perpendicular to the longitudinal direction of a watercraft body with respect to the engine. Furthermore, in this small watercraft, the water lock is located on a second side in the width direction of the watercraft body with respect to the engine.

In the small watercraft described in Japanese Patent Laid-Open No. 11-245895, the catalyst is located on the first side in the width direction of the watercraft body with respect to the engine while the water lock is located on the second side in the width direction of the watercraft body with respect to the engine, and hence the size of the watercraft body in the width direction is increased, as in the small watercraft described in Japanese Patent Laid-Open No. 11-245895.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a jet propelled watercraft and a jet propulsion assembly that significantly reduce or prevent an increase in the size of a watercraft body in a width direction.

A jet propelled watercraft according to a preferred embodiment of the present invention includes a watercraft body, an engine housed in the watercraft body and provided with an exhaust port on a side surface in a width direction that is perpendicular to a longitudinal direction of the watercraft body, a first exhaust pipe connected to the exhaust port, a catalyst storage connected to the first exhaust pipe, a second exhaust pipe connected to the catalyst storage, and a water lock connected to the second exhaust pipe. The catalyst storage overlaps with the side surface of the engine in a side view, and the catalyst storage and the water lock are located outward in the width direction with respect to the exhaust port of the engine in a plan view.

In a jet propelled watercraft according to a preferred embodiment of the present invention, the catalyst storage and the water lock are located outward in the width direction with respect to the exhaust port of the engine in the plan view. Thus, both the catalyst storage and the water lock are located only on one side in the width direction of the watercraft body with respect to the engine (outward in the width direction with respect to the exhaust port). Consequently, the size in the width direction of a region in which the engine, the catalyst storage, and the water lock are located is reduced as compared with the case where the catalyst storage and the water lock are located on both sides in the width direction with respect to the engine, respectively, and hence an increase in the size of the watercraft body in the width direction is significantly reduced or prevented. Furthermore, in this structure, the catalyst storage and the water lock are located on one side in the width direction of the watercraft body with respect to the engine (outward in the width direction with respect to the exhaust port), and hence the length of the exhaust pipe (second exhaust pipe) that connects the catalyst storage to the water lock is reduced as compared with the case where the catalyst storage and the water lock are located on both sides in the width direction with respect to the engine, respectively. Consequently, an increase in the weight of the exhaust pipe (second exhaust pipe) that connects the catalyst storage to the water lock is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body is significantly reduced or prevented.

Furthermore, in a jet propelled watercraft according to a preferred embodiment of the present invention, the catalyst storage overlaps with the side surface of the engine in the side view. Thus, an increase in the size of the watercraft body in a vertical direction or the longitudinal direction is significantly reduced or prevented as compared with the case where the catalyst storage is totally outside of the side surface of the engine in the side view. Furthermore, in this structure, the catalyst storage is located closer to the exhaust port as compared with the case where the catalyst storage is totally outside of the side surface of the engine in the side view. Consequently, the length of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is reduced. Thus, an increase in the weight of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is significantly reduced or prevented, and hence an increase in the weight of the watercraft body is significantly reduced or prevented.

In a jet propelled watercraft according to a preferred embodiment of the present invention, the first exhaust pipe and the second exhaust pipe preferably overlap with the side surface of the engine in the side view. Accordingly, in addition to the catalyst storage, the first exhaust pipe and the second exhaust pipe overlap with the side surface of the engine in the side view, and hence an increase in the size of the watercraft body in the vertical direction or the longitudinal direction is effectively significantly reduced or prevented.

In a jet propelled watercraft according to a preferred embodiment of the present invention, the exhaust port preferably includes a plurality of exhaust ports provided on the side surface of the engine, and the catalyst storage is preferably located forward relative to a back end of a rearward most exhaust port of the plurality of exhaust ports and rearward relative to a front end of a forward most exhaust port of the plurality of exhaust ports. Accordingly, the catalyst storage is located close to the exhaust port. As used herein, “close to”indicates adjacent to or in a vicinity of. Consequently, the length of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is further reduced such that an increase in the weight of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is further significantly reduced or prevented. Consequently, an increase in the weight of the watercraft body is further significantly reduced or prevented.

In a jet propelled watercraft according to a preferred embodiment of the present invention, the first exhaust pipe preferably includes a bent portion that extends forward of the exhaust port, is bent back, and extends rearward. Accordingly, the first exhaust pipe extends forward and thereafter extends rearward due to the bent portion, and hence the first exhaust pipe and the catalyst storage are connected to each other at a position that is farther forward as compared with the case where the first exhaust pipe extends only rearward of the exhaust port. Consequently, the catalyst storage is located at a more forward position, and hence the catalyst storage is easily located at a position at which the catalyst storage overlaps with the side surface of the engine.

In this case, the exhaust port preferably includes a plurality of exhaust ports provided on the side surface of the engine, and the bent portion of the first exhaust pipe preferably extends forward of a forward most exhaust port of the plurality of exhaust ports, is bent back, and extends rearward. Accordingly, even in a structure in which the plurality of exhaust ports are provided on the side surface of the engine, the catalyst storage is located forward such that the catalyst storage is easily located at the position at which the catalyst storage overlaps with the side surface of the engine.

In a structure in which the first exhaust pipe includes the bent portion, the bent portion preferably overlaps with the side surface of the engine in the side view. Accordingly, the bent portion is provided such that an increase in the size of the watercraft body in the vertical direction or the longitudinal direction is significantly reduced or prevented.

In a structure in which the first exhaust pipe includes the bent portion, the bent portion is preferably bent back near a front end of the engine. Accordingly, the length of the bent portion of the first exhaust pipe is reduced as compared with the case where the bent portion of the first exhaust pipe is bent back at a forward position relative to a front end of the engine. Consequently, an increase in the weight of the first exhaust pipe is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body is significantly reduced or prevented.

In a structure in which the first exhaust pipe includes the bent portion, a portion of the bent portion before being bent back and a portion of the bent portion after being bent back preferably overlap with each other in the side view. Accordingly, the portion of the bent portion before bending back and the portion of the bent portion after bending back are located close to each other, and hence the length of the bent portion is reduced. Consequently, an increase in the weight of the first exhaust pipe is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body is significantly reduced or prevented.

In a structure in which the first exhaust pipe includes the bent portion, the first exhaust pipe preferably further includes a lead-out portion that connects the exhaust port of the engine to the bent portion and an increased diameter portion that connects the bent portion to the catalyst storage, and the lead-out portion, the bent portion, and the increased diameter portion are preferably integral and unitary with each other. Accordingly, the number of components of an exhaust passage is reduced as compared with the case where at least one of the lead-out portion, the bent portion, and the increased diameter portion is separately provided. Consequently, the structure of the exhaust passage is simplified.

In a jet propelled watercraft according to a preferred embodiment of the present invention, the catalyst storage is preferably integral and unitary with the first exhaust pipe. Accordingly, the number of components of the exhaust passage is reduced as compared with the case where the catalyst storage is provided separately from the first exhaust pipe. Consequently, the structure of the exhaust passage is simplified.

In a jet propelled watercraft according to a preferred embodiment of the present invention, a bottom of an exhaust gas passage of the first exhaust pipe is preferably located below the exhaust port. Accordingly, when moisture in the exhaust gas is condensed to generate condensed water, accumulation of the condensed water between the exhaust port and the first exhaust pipe is significantly reduced or prevented. Consequently, blockage of the exhaust gas flow caused by the accumulation of the condensed water is significantly reduced or prevented.

In this case, a bottom of an exhaust gas passage of the catalyst storage is preferably located at a same or substantially a same height as the bottom of the exhaust gas passage of the first exhaust pipe or is preferably located below the bottom of the exhaust gas passage of the first exhaust pipe, a bottom of an exhaust gas passage of the second exhaust pipe is preferably located at a same or substantially a same height as the bottom of the exhaust gas passage of the catalyst storage or is preferably located below the bottom of the exhaust gas passage of the catalyst storage, and a bottom of an exhaust gas passage of the water lock is preferably located at a same or substantially a same height as the bottom of the exhaust gas passage of the second exhaust pipe or is preferably located below the bottom of the exhaust gas passage of the second exhaust pipe. Accordingly, a rising slope in the exhaust passage from the exhaust port to the water lock is significantly reduced or prevented. Consequently, accumulation of the condensed water between the exhaust port and the water lock is significantly reduced or prevented. Thus, blockage of the exhaust gas flow caused by the accumulation of the condensed water is significantly reduced or prevented. Furthermore, a degradation of the performance of a catalyst in the catalyst storage caused by a decrease in the temperature of the catalyst resulting from the accumulation of the condensed water is significantly reduced or prevented.

In a jet propelled watercraft according to a preferred embodiment of the present invention, an upper end of the catalyst storage and an upper end of the water lock are preferably located below an upper end of the engine in the side view, and a lower end of the catalyst storage and a lower end of the water lock are preferably located above a lower end of the engine in the side view. Accordingly, an increase in the size of the watercraft body in the vertical direction is significantly reduced or prevented as compared with the case where the upper ends of the catalyst storage and the water lock are located below the lower end of the engine or the lower ends of the catalyst storage and the water lock are located above the upper end of the engine.

In a jet propelled watercraft according to a preferred embodiment of the present invention, the catalyst storage preferably overlaps with the first exhaust pipe in the side view. Accordingly, the catalyst storage and the first exhaust pipe are located close to each other, and hence the length of the first exhaust pipe is reduced. Consequently, an increase in the weight of the first exhaust pipe is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body is significantly reduced or prevented.

In this case, a portion of a side surface of the catalyst storage and a portion of a side surface of the first exhaust pipe are preferably integral and unitary with each other. Accordingly, the catalyst storage is located close to the exhaust port, and hence an increase in the size of the watercraft body in the width direction is further significantly reduced or prevented. Furthermore, in this structure, the catalyst storage and the first exhaust pipe are located close to each other, and hence the length of the first exhaust pipe is further reduced such that an increase in the weight of the first exhaust pipe is further significantly reduced or prevented. Consequently, an increase in the weight of the watercraft body is further significantly reduced or prevented.

A jet propulsion assembly according to a preferred embodiment of the present invention includes an engine housed in a watercraft body and provided with an exhaust port on a side surface in a width direction perpendicular to a longitudinal direction of the watercraft body, a first exhaust pipe connected to the exhaust port, a catalyst storage connected to the first exhaust pipe, a second exhaust pipe connected to the catalyst storage, and a water lock connected to the second exhaust pipe. The catalyst storage overlaps with the side surface of the engine in a side view, and the catalyst storage and the water lock are located outward in the width direction with respect to the exhaust port of the engine in a plan view.

In a jet propulsion assembly according to a preferred embodiment of the present invention, the catalyst storage and the water lock are located outward in the width direction with respect to the exhaust port of the engine in the plan view. Thus, both the catalyst storage and the water lock are located only on one side in the width direction of the watercraft body with respect to the engine (outward in the width direction with respect to the exhaust port). Consequently, the size in the width direction of a region in which the engine, the catalyst storage, and the water lock are located is reduced as compared with the case where the catalyst storage and the water lock are located on both sides in the width direction with respect to the engine, respectively, and hence an increase in the size of the watercraft body in the width direction is significantly reduced or prevented. Furthermore, in this structure, the catalyst storage and the water lock are located on one side in the width direction of the watercraft body with respect to the engine (outward in the width direction with respect to the exhaust port), and hence the length of the exhaust pipe (second exhaust pipe) that connects the catalyst storage to the water lock is reduced as compared with the case where the catalyst storage and the water lock are located on both sides in the width direction with respect to the engine, respectively. Consequently, an increase in the weight of the exhaust pipe (second exhaust pipe) that connects the catalyst storage to the water lock is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body is significantly reduced or prevented.

Furthermore, in a jet propulsion assembly according to a preferred embodiment of the present invention, the catalyst storage overlaps with the side surface of the engine in the side view. Thus, an increase in the size of the watercraft body in a vertical direction or the longitudinal direction is significantly reduced or prevented as compared with the case where the catalyst storage is totally outside of the side surface of the engine in the side view. Furthermore, in this structure, the catalyst storage is located closer to the exhaust port as compared with the case where the catalyst storage is totally outside of the side surface of the engine in the side view. Consequently, the length of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is reduced. Thus, an increase in the weight of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is significantly reduced or prevented, and hence an increase in the weight of the watercraft body is significantly reduced or prevented.

In a jet propulsion assembly according to a preferred embodiment of the present invention, the first exhaust pipe and the second exhaust pipe preferably overlap with the side surface of the engine in the side view. Accordingly, in addition to the catalyst storage, the first exhaust pipe and the second exhaust pipe overlap with the side surface of the engine in the side view, and hence an increase in the size of the watercraft body in the vertical direction or the longitudinal direction is effectively significantly reduced or prevented.

In a jet propulsion assembly according to a preferred embodiment of the present invention, the exhaust port preferably includes a plurality of exhaust ports provided on the side surface of the engine, and the catalyst storage is preferably located forward relative to a back end of a rearward most exhaust port of the plurality of exhaust ports and rearward relative to a front end of a forward most exhaust port of the plurality of exhaust ports. Accordingly, the catalyst storage is located close to the exhaust port. Consequently, the length of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is further reduced such that an increase in the weight of the exhaust pipe (first exhaust pipe) that connects the exhaust port to the catalyst storage is further significantly reduced or prevented. Consequently, an increase in the weight of the watercraft body is further significantly reduced or prevented.

In a jet propulsion assembly according to a preferred embodiment of the present invention, the first exhaust pipe preferably includes a bent portion that extends forward of the exhaust port, is bent back, and extends rearward. Accordingly, the first exhaust pipe extends forward and thereafter extends rearward due to the bent portion, and hence the first exhaust pipe and the catalyst storage are connected to each other at a position that is farther forward as compared with the case where the first exhaust pipe extends only rearward of the exhaust port. Consequently, the catalyst storage is located at a more forward position, and hence the catalyst storage is easily located at a position at which the catalyst storage overlaps with the side surface of the engine.

In this case, the exhaust port preferably includes a plurality of exhaust ports provided on the side surface of the engine, and the bent portion of the first exhaust pipe preferably extends forward of a forward most exhaust port of the plurality of exhaust ports, is bent back, and extends rearward. Accordingly, even in a structure in which the plurality of exhaust ports are provided on the side surface of the engine, the catalyst storage is located forward such that the catalyst storage is easily located at the position at which the catalyst storage overlaps with the side surface of the engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are hereinafter described with reference to the drawings. In the following description, a front-back direction, a vertical direction, and a right-left direction are directions relative to a jet propelled watercraft1. More specifically, the forward movement direction (along arrow FWD) of the jet propelled watercraft1is a front side, and the backward movement direction (along arrow BWD) of the jet propelled watercraft1is a rear side. A right side with respect to the forward movement direction of the jet propelled watercraft1is the right, and a left side with respect to the forward movement direction of the jet propelled watercraft1is the left. In the following description, the front-back direction is also referred to as the longitudinal direction of a watercraft body2, and the right-left direction is also referred to as the width direction of the watercraft body2.

The structure of the jet propelled watercraft1according to a preferred embodiment of the present invention is now described with reference toFIGS. 1 to 7.

As shown inFIG. 1, the jet propelled watercraft1includes the watercraft body2and a jet propulsion assembly (jet propulsion mechanism)3. The jet propulsion assembly3includes a jet propulsion unit4and an engine5. The jet propelled watercraft1includes a handle6and a seat7. The handle6is operated to the right and left by a crew member P. The crew member P sits on the seat7.

The watercraft body2includes a hull21that floats on the surface of the water and a deck22located above the surface of water. The deck22is located above the hull21including a watercraft bottom. The engine5is located between the hull21and the deck22in the vertical direction. The engine5is housed in an engine room2aprovided inside the watercraft body2. In the engine room2a, a fuel tank2bis also housed. The jet propulsion unit4is located behind the engine5. The seat7is located above the engine5. The handle6is located in front of a seating surface of the seat7. The handle6and the seat7are located above the watercraft body2.

The jet propulsion unit4suctions and jets water with the drive force of the engine5. The jet propulsion unit4includes a water inlet41, a water outlet42, and a flow passage43. The water inlet41is open at the watercraft bottom. The water suctioned through the water inlet41is jetted rearward from the water outlet42. The water suctioned through the water inlet41is guided to the water outlet42through the flow passage43.

The jet propulsion unit4includes a drive shaft44, an impeller45, a nozzle46, a deflector47, and a bucket48. A front end of the drive shaft44is located in the engine room2a. A back end of the drive shaft44is located in the flow passage43. The front end of the drive shaft44is mounted to the engine5through a coupling11. The impeller45is mounted in the vicinity of the back end of the drive shaft44. The impeller45is located in the flow passage43. The impeller45rotates with the rotation of the drive shaft44.

The nozzle46includes the water outlet42. The nozzle46is located behind the impeller45. The deflector47is mounted on the nozzle46. The deflector47is located behind the nozzle46. The deflector47rotates in the right-left direction with respect to the nozzle46about an axis that extends in the vertical direction. Thus, the deflector47changes the direction of the water jetted from the nozzle46in the right-left direction. The deflector47rotates in the right-left direction in response to operation of the handle6. The bucket48is located behind the deflector47. The bucket48rotates in the vertical direction with respect to the deflector47about an axis that extends in the right-left direction. Thus, the bucket48changes the direction of the water jetted from the deflector47to the forward direction or the rearward direction. The bucket48rotates in the vertical direction in response to operation of a shift lever (not shown).

The crew member P operates a throttle lever (not shown) provided on the handle6to adjust the output of the engine5. When the engine5rotates the drive shaft44, the impeller45is rotated with the drive shaft44. Consequently, a force to suction water outside the watercraft into the flow passage43through the water inlet41is generated. The water suctioned into the flow passage43passes through the impeller45, the nozzle46, and the deflector47, in this order, and is jetted rearward from the deflector47. Thus, a thrust to propel the jet propelled watercraft1is generated. The direction of the water jetted from the deflector47is changed in the right-left direction by the rotation of the deflector47in the right-left direction in response to operation of the handle6. The direction of the water jetted from the deflector47is changed from the forward direction to the rearward direction by the rotation of the bucket48in a downward direction in response to operation of the shift lever, and is changed from the rearward direction to the forward direction by the rotation of the bucket48in an upward direction in response to operation of the shift lever. Consequently, the jet propelled watercraft1is steered.

As shown inFIG. 2, the engine5is an internal combustion engine. The engine5is preferably an in-line engine. The engine5includes a crankshaft51, a plurality of (for example, three in a preferred embodiment of the present invention) pistons52, and a plurality of (for example, three in a preferred embodiment of the present invention) connecting rods53. The crankshaft51is rotatable about the axis Ac of the crankshaft that extends in the front-back direction. A back end of the crankshaft51is mounted to the jet propulsion unit4(seeFIG. 1) through the coupling11. A front end of the crankshaft51is mounted to a power generator59described below. Each of the pistons52reciprocates in the vertical direction according to the rotation of the crankshaft51. Each of the connecting rods53couples a corresponding piston52to the crankshaft51.

As shown inFIGS. 2 and 3, the engine5includes a crank case54, a cylinder body55, a cylinder head56, and a cylinder head cover57. The crank case54as well as the cylinder body55houses the crankshaft51. The cylinder body55is provided with a plurality of (for example, three in a preferred embodiment of the present invention) cylinders55athat contain the plurality of pistons52, respectively. The cylinder head56is provided with a plurality of (for example, three in a preferred embodiment of the present invention) combustion chambers56a, a plurality of (for example, three in a preferred embodiment of the present invention) exhaust ports56b, and a plurality of intake ports (not shown). The plurality of exhaust ports56bare provided on a side surface5aof the engine5in the width direction perpendicular to the longitudinal direction (front-back direction) of the watercraft body2. The side surface5aincludes side surfaces of the crank case54, the cylinder body55, the cylinder head56, and the cylinder head cover57. The plurality of exhaust ports56bare aligned in the front-back direction. The cylinder head cover57covers the cylinder head56. The crank case54, the cylinder body55, the cylinder head56, and the cylinder head cover57are aligned in the vertical direction, in this order, from the bottom.

In the jet propulsion assembly3, a case cover58is mounted on the engine5. The case cover58is located below the cylinder head56. The case cover58is located in front of the crank case54and the cylinder body55. The case cover58houses the power generator59. The power generator59converts the power of the engine5to electric power by the relative rotation of a rotor (not shown) with respect to a stator (not shown) due to the rotation of the crankshaft51.

The jet propulsion assembly3includes an air intake apparatus60. The air intake apparatus60is mounted to the engine5. The air intake apparatus60is located in front of the engine5and on the right of the engine5. The air intake apparatus60includes an air intake box61, an air filter62, and an intake pipe63(seeFIG. 4). The air intake box61stores the air filter62. The air filter62removes extraneous material in the air. The intake pipe63guides air discharged from the air intake box61to the plurality of combustion chambers56athrough the intake ports.

The air intake box61includes an air intake inlet64, an air intake outlet65, and an air intake passage66. The air intake inlet64is opened at a front upper portion of the air intake box61. The air suctioned through the air intake inlet64is discharged from the air intake outlet65. The air intake outlet65is connected to the intake pipe63. The air intake passage66connects the air intake inlet64to the air intake outlet65. InFIG. 2, the air flow is shown by a thick one-dot chain line.

As shown inFIGS. 1 and 3 to 6, the jet propulsion assembly3includes an exhaust passage8. The exhaust passage8is mounted to the engine5. Exhaust gas discharged from the plurality of exhaust ports56bis discharged outward of the watercraft body2through the exhaust passage8. The exhaust passage8includes a first exhaust pipe81, a catalyst storage82, a second exhaust pipe83, a water lock84, and a third exhaust pipe85(seeFIG. 1).

The exhaust gas discharged from the exhaust ports56bis led out through the first exhaust pipe81. The catalyst storage82stores a catalyst member82a(seeFIGS. 3 and 4) that enhances the reaction of a component (such as HC, CO, or NOx) contained in the exhaust gas. The second exhaust pipe83guides the exhaust gas passing through the catalyst storage82to the water lock84. The water lock84significantly reduces or prevents inflow, toward the engine5, of water entering from an exhaust opening85a(seeFIG. 1) through which the exhaust gas is externally discharged. The third exhaust pipe85discharges the exhaust gas discharged from the exhaust ports56boutward of the watercraft body2(into water).

An upstream portion of the first exhaust pipe81in the flow direction of the exhaust gas is connected to the exhaust ports56b. A downstream portion of the first exhaust pipe81in the flow direction of the exhaust gas is connected to the catalyst storage82. An upstream portion of the catalyst storage82in the flow direction of the exhaust gas is connected to the first exhaust pipe81. A downstream portion of the catalyst storage82in the flow direction of the exhaust gas is connected to the second exhaust pipe83. An upstream portion of the second exhaust pipe83in the flow direction of the exhaust gas is connected to the catalyst storage82. A downstream portion of the second exhaust pipe83in the flow direction of the exhaust gas is connected to the water lock84. An upstream portion of the water lock84in the flow direction of the exhaust gas is connected to the second exhaust pipe83. A downstream portion of the water lock84in the flow direction of the exhaust gas is connected to the third exhaust pipe85. An upstream portion of the third exhaust pipe85in the flow direction of the exhaust gas is connected to the water lock84. A downstream end of the third exhaust pipe85in the flow direction of the exhaust gas is opened outward of the watercraft body2. The downstream end of the third exhaust pipe85includes the exhaust opening85a. In the exhaust passage8, the exhaust gas passes through the first exhaust pipe81, the catalyst storage82, the second exhaust pipe83, the water lock84, and the third exhaust pipe85, in this order, and is discharged outward of the watercraft body2.

The first exhaust pipe81includes a lead-out portion81a, a bent portion81b, and an increased diameter portion81c. An upstream portion of the lead-out portion81ain the flow direction of the exhaust gas is connected to the exhaust ports56b. A downstream portion of the lead-out portion81ain the flow direction of the exhaust gas is connected to the bent portion81b. The lead-out portion81aincludes a plurality of (for example, three in a preferred embodiment of the present invention) branches81dand a trunk81e. The plurality of branches81dare aligned in the front-back direction. Each of the branches81dis connected to a corresponding exhaust port56b. The trunk81econnects the plurality of branches81dto each other. In the trunk81e, the exhaust gas to be led out from the exhaust ports56bthrough the branches81dis gathered. The trunk81eextends in the front-back direction.

An upstream portion of the bent portion81bin the flow direction of the exhaust gas is connected to the lead-out portion81a. A downstream portion of the bent portion81bin the flow direction of the exhaust gas is connected to the increased diameter portion81c. The bent portion81bextends forward of a forward most exhaust port56bof the plurality of exhaust ports56b, is bent back, and extends rearward. A portion81fof the bent portion81bbefore being bent and a portion81gof the bent portion81bafter being bent overlap with each other in a side view. In other words, the portion81fof the bent portion81bbefore being bent and the portion81gof the bent portion81bafter being bent are aligned in the width direction. The bent portion81bis bent back near a front end of the engine5. The bent portion81bis preferably U-shaped or substantially U-shaped.

An upstream portion of the increased diameter portion81cin the flow direction of the exhaust gas is connected to the bent portion81b. A downstream portion of the increased diameter portion81cin the flow direction of the exhaust gas is connected to the catalyst storage82. The increased diameter portion81chas a sectional area that gradually increases downstream in the flow direction of the exhaust gas.

The catalyst storage82stores the catalyst member82a. The catalyst member82ais preferably a columnar member having a honeycomb structure, for example, and a catalyst is supported thereon. The catalyst member82ais fitted into and fixed to the catalyst storage82, for example. The catalyst supported on the catalyst member82aefficiently reacts with the components contained in the exhaust gas at a catalytic activation temperature or higher. In order not to decrease the temperature of the exhaust gas that reaches the catalyst member82ato less than the catalytic activation temperature, the catalyst member82ais located in a vicinity of the exhaust ports56bof the engine5. Specifically, the catalyst member82ais located such that the length of a flow passage for the exhaust gas from an exhaust port56bclosest to the catalyst member82ato a front end of the catalyst member82ais not more than about 500 mm, for example.

The second exhaust pipe83includes a decreased diameter portion83aand a straight pipe83b. An upstream portion of the decreased diameter portion83ain the flow direction of the exhaust gas is connected to the catalyst storage82. A downstream portion of the decreased diameter portion83ain the flow direction of the exhaust gas is connected to the straight pipe83b. The decreased diameter portion83ahas a sectional area that gradually decreases downstream in the flow direction of the exhaust gas. An upstream portion of the straight pipe83bin the flow direction of the exhaust gas is connected to the decreased diameter portion83a. A downstream portion of the straight pipe83bin the flow direction of the exhaust gas is connected to the water lock84.

According to a preferred embodiment of the present invention, the first exhaust pipe81, the catalyst storage82, the second exhaust pipe83, and the water lock84are located outward (left) in the width direction with respect to the exhaust ports56bof the engine5in a plan view. The term “outward in the width direction” denotes a direction spaced from the center of the engine5in the width direction. The first exhaust pipe81, the catalyst storage82, and the second exhaust pipe83overlap with the side surface5aof the engine5in the side view. Specifically, the first exhaust pipe81(the entirety of the lead-out portion81a, the bent portion81b, and the increased diameter portion81c) and the catalyst storage82totally overlap with the side surface5aof the engine5in the side view. The second exhaust pipe83(the decreased diameter portion83aand the straight pipe83b) partially overlaps with the side surface5aof the engine5in the side view.

The catalyst storage82is located rearward relative to the front end of the engine5and forward relative to a back end of the engine5. Specifically, the catalyst storage82is located forward relative to a back end of a rearward most exhaust port56bof the plurality of exhaust ports56band rearward relative to a front end of the forward most exhaust port56bof the plurality of exhaust ports56b. In other words, the catalyst storage82is located between the rearward most exhaust port56bof the plurality of exhaust ports56band the forward most exhaust port56bof the plurality of exhaust ports56bin the front-back direction.

An upper end of the first exhaust pipe81, an upper end of the catalyst storage82, an upper end of the second exhaust pipe83, and an upper end of the water lock84are located below an upper end of the engine5in the side view. A lower end of the first exhaust pipe81, a lower end of the catalyst storage82, a lower end of the second exhaust pipe83, and a lower end of the water lock84are located above a lower end of the engine5in the side view.

According to a preferred embodiment of the present invention, the catalyst storage82is integral and unitary with the first exhaust pipe81. Specifically, the first exhaust pipe81and the catalyst storage82are, for example, cast as an integral and unitary structure. Therefore, in the first exhaust pipe81, the lead-out portion81a, the bent portion81b, and the increased diameter portion81care, for example, cast together. Thus, no connecting member to connect the lead-out portion81a, the bent portion81b, and the increased diameter portion81cto each other is required, and no connecting member to connect the first exhaust pipe81and the catalyst storage82to each other is required. The first exhaust pipe81and the catalyst storage82are preferably cast from metal such as aluminum.

The lead-out portion81aof the first exhaust pipe81and the catalyst storage82are aligned in the right-left direction, in this order, from the right in the plan view. The catalyst storage82overlaps with the trunk81eof the lead-out portion81aof the first exhaust pipe81in the side view.

As shown inFIGS. 4, 5, and 7, a portion82b(i.e., a right portion of the catalyst storage82) of a side surface of the catalyst storage82and a portion81h(i.e., a left portion of the trunk81eof the first exhaust pipe81) of a side surface of the first exhaust pipe81are integral and unitary with each other. Specifically, the right portion82bof the catalyst storage82and the left portion81hof the trunk81eof the first exhaust pipe81are, for example, cast as an integral and unitary structure.

As shown inFIGS. 6 and 7, the first exhaust pipe81includes a cooling water passage81i. Water flows through the cooling water passage81ito cool the first exhaust pipe81. The cooling water passage81iis integral and unitary with the first exhaust pipe81. Specifically, the cooling water passage81iis, for example, cast as a portion of the first exhaust pipe81. The cooling water passage81isurrounds an exhaust gas passage81jof the first exhaust pipe81.

The catalyst storage82includes a cooling water passage82c. Water flows through the cooling water passage82cto cool the catalyst storage82and the catalyst member82aof the catalyst storage82. The cooling water passage82cis integral and unitary with the catalyst storage82. Specifically, the cooling water passage82cis, for example, cast as a portion of the catalyst storage82. The cooling water passage82csurrounds an exhaust gas passage82dof the catalyst storage82.

As shown inFIG. 7, at least a portion of the cooling water passage81iof the first exhaust pipe81and at least a portion of the cooling water passage82cof the catalyst storage82share and define a common cooling water passage86. The common cooling water passage86is provided in a region in which the right portion82bof the catalyst storage82and the left portion81hof the trunk81eof the first exhaust pipe81are integral and unitary with each other.

As shown inFIG. 6, the second exhaust pipe83includes a cooling water passage83c. Water flows through the cooling water passage83cto cool the second exhaust pipe83. The cooling water passage83csurrounds an exhaust gas passage83dof the second exhaust pipe83.

According to a preferred embodiment of the present invention, the exhaust passage8is provided such that an exhaust gas passage from the first exhaust pipe81to the water lock84has no rising slope, as shown inFIGS. 6 and 7. Thus, a bottom of the exhaust gas passage81jof the first exhaust pipe81is located below the exhaust ports56b. A bottom of the exhaust gas passage82dof the catalyst storage82is located at the same or substantially the same height as the bottom of the exhaust gas passage81jof the first exhaust pipe81. A bottom of the exhaust gas passage83dof the second exhaust pipe83is located at the same or substantially the same height as the bottom of the exhaust gas passage82dof the catalyst storage82. A bottom of an exhaust gas passage of the water lock84is located at the same or substantially the same height as the bottom of the exhaust gas passage83dof the second exhaust pipe83.

More specifically, a bottom of the exhaust gas passage81jof the lead-out portion81aof the first exhaust pipe81is located below the exhaust ports56b. A bottom of the exhaust gas passage81jof the bent portion81bof the first exhaust pipe81is located below the bottom of the exhaust gas passage81jof the lead-out portion81a. A bottom of the exhaust gas passage81jof the increased diameter portion81cof the first exhaust pipe81is located below the bottom of the exhaust gas passage81jof the bent portion81b.

The bottom of the exhaust gas passage82dof the catalyst storage82is located at the same or substantially the same height as the bottom of the exhaust gas passage81jof the increased diameter portion81c. A bottom of the exhaust gas passage83dof the decreased diameter portion83aof the second exhaust pipe83is located at the same or substantially the same height as the bottom of the exhaust gas passage82dof the catalyst storage82. A bottom of the exhaust gas passage83dof the straight pipe83bof the second exhaust pipe83is located at the same or substantially the same height as the bottom of the exhaust gas passage83dof the decreased diameter portion83aof the second exhaust pipe83. The bottom of the exhaust gas passage of the water lock84is located below the bottom of the exhaust gas passage83dof the straight pipe83bof the second exhaust pipe83.

According to various preferred embodiments of the present invention, the following advantageous effects are obtained.

According to a preferred embodiment of the present invention, the catalyst storage82and the water lock84are located outward in the width direction with respect to the exhaust ports56bof the engine5in the plan view. Thus, both the catalyst storage82and the water lock84are located only on one side in the width direction of the watercraft body2with respect to the engine5(outward in the width direction with respect to the exhaust ports56b). Consequently, the size in the width direction of a region in which the engine5, the catalyst storage82, and the water lock84are located is reduced as compared with the case where the catalyst storage82and the water lock84are located on both sides in the width direction with respect to the engine5, respectively, and hence an increase in the size of the watercraft body2in the width direction is significantly reduced or prevented. Furthermore, the catalyst storage82and the water lock84are located on one side in the width direction of the watercraft body2with respect to the engine5(outward in the width direction with respect to the exhaust ports56b), and hence the length of the exhaust pipe (second exhaust pipe83) that connects the catalyst storage82to the water lock84is reduced as compared with the case where the catalyst storage82and the water lock84are located on both sides in the width direction with respect to the engine5, respectively. Consequently, an increase in the weight of the exhaust pipe (second exhaust pipe83) that connects the catalyst storage82to the water lock84is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body2is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the catalyst storage82overlaps with the side surface5aof the engine5in the side view. Thus, an increase in the size of the watercraft body2in the vertical direction or the longitudinal direction is significantly reduced or prevented as compared with the case where the catalyst storage82is totally outside of the side surface5aof the engine5in the side view. Furthermore, the catalyst storage82is located closer to the exhaust ports56bas compared with the case where the catalyst storage82is totally outside of the side surface5aof the engine5in the side view. Consequently, the length of the exhaust pipe (first exhaust pipe81) that connects the exhaust ports56bto the catalyst storage82is reduced. Thus, an increase in the weight of the exhaust pipe (first exhaust pipe81) that connects the exhaust ports56bto the catalyst storage82is significantly reduced or prevented, and hence an increase in the weight of the watercraft body2is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the first exhaust pipe81and the second exhaust pipe83overlap with the side surface5aof the engine5in the side view. Thus, in addition to the catalyst storage82, the first exhaust pipe81and the second exhaust pipe83overlap with the side surface5aof the engine5in the side view, and hence an increase in the size of the watercraft body2in the vertical direction or the longitudinal direction is effectively significantly reduced or prevented.

According to a preferred embodiment of the present invention, the catalyst storage82is located forward relative to a back end of the rearward most exhaust port56bof the plurality of exhaust ports56band rearward relative to a front end of the forward most exhaust port56bof the plurality of exhaust ports56b. Thus, the catalyst storage82is located close to the exhaust ports56b. Consequently, the length of the exhaust pipe (first exhaust pipe81) that connects the exhaust ports56bto the catalyst storage82is further reduced such that an increase in the weight of the exhaust pipe (first exhaust pipe81) that connects the exhaust ports56bto the catalyst storage82is further significantly reduced or prevented. Consequently, an increase in the weight of the watercraft body2is further significantly reduced or prevented.

According to a preferred embodiment of the present invention, the bent portion81bthat extends forward of the exhaust ports56b, is bent back, and extends rearward is provided in the first exhaust pipe81. Thus, the first exhaust pipe81extends forward and thereafter extends rearward due to the bent portion81b, and hence the first exhaust pipe81and the catalyst storage82are connected to each other at a position that is farther forward as compared with the case where the first exhaust pipe81extends only rearward of the exhaust ports56b. Consequently, the catalyst storage82is located at a more forward position, and hence the catalyst storage82is easily located at a position at which the catalyst storage82overlaps with the side surface5aof the engine5.

According to a preferred embodiment of the present invention, the bent portion81bof the first exhaust pipe81extends forward of the forward most exhaust port56bof the plurality of exhaust ports56b, is bent back, and extends rearward. Thus, even in a structure in which the plurality of exhaust ports56bare provided on the side surface5aof the engine5, the catalyst storage82is located forward such that the catalyst storage82is easily located at the position at which the catalyst storage82overlaps with the side surface5aof the engine5.

According to a preferred embodiment of the present invention, the bent portion81boverlaps with the side surface5aof the engine5in the side view. Thus, the bent portion81bis provided such that an increase in the size of the watercraft body2in the vertical direction or the longitudinal direction is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the bent portion81bis bent back near the front end of the engine5. Thus, the length of the bent portion81bof the first exhaust pipe81is reduced as compared with the case where the bent portion81bof the first exhaust pipe81is bent back at a forward position relative to the front end of the engine5. Consequently, an increase in the weight of the first exhaust pipe81is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body2is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the portion81fof the bent portion81bbefore being bent and the portion81gof the bent portion81bafter being bent overlap with each other in the side view. Thus, the portion81fof the bent portion81bbefore being bent and the portion81gof the bent portion81bafter being bent are located close to each other, and hence the length of the bent portion81bis reduced. Consequently, an increase in the weight of the first exhaust pipe81is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body2is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the lead-out portion81athat connects the exhaust ports56bof the engine5to the bent portion81band the increased diameter portion81cthat connects the bent portion81bto the catalyst storage82are provided in the first exhaust pipe81. Furthermore, the lead-out portion81a, the bent portion81b, and the increased diameter portion81care integral and unitary with each other. Thus, the number of components of the exhaust passage8is reduced as compared with the case where at least one of the lead-out portion81a, the bent portion81b, and the increased diameter portion81cis separately provided. Consequently, the structure of the exhaust passage8is simplified.

According to a preferred embodiment of the present invention, the catalyst storage82is integral and unitary with the first exhaust pipe81. Thus, the number of components of the exhaust passage8is reduced as compared with the case where the catalyst storage82is provided separately from the first exhaust pipe81. Consequently, the structure of the exhaust passage8is simplified.

According to a preferred embodiment of the present invention, the bottom of the exhaust gas passage81jof the first exhaust pipe81is located below the exhaust ports56b. Thus, when moisture in the exhaust gas is condensed to generate condensed water, accumulation of the condensed water between the exhaust ports56band the first exhaust pipe81is significantly reduced or prevented. Consequently, blockage of exhaust gas flow caused by the accumulation of the condensed water is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the bottom of the exhaust gas passage82dof the catalyst storage82is located at the same or substantially the same height as the bottom of the exhaust gas passage81jof the first exhaust pipe81. Furthermore, the bottom of the exhaust gas passage83dof the second exhaust pipe83is located at the same or substantially the same height as the bottom of the exhaust gas passage82dof the catalyst storage82. In addition, the bottom of the exhaust gas passage of the water lock84is located at the same or substantially the same height as the bottom of the exhaust gas passage83dof the second exhaust pipe83. Thus, a rising slope in the exhaust passage8from the exhaust ports56bto the water lock84is significantly reduced or prevented. Consequently, accumulation of the condensed water between the exhaust ports56band the water lock84is significantly reduced or prevented. Thus, blockage of the exhaust gas flow caused by the accumulation of the condensed water is significantly reduced or prevented. Furthermore, a degradation of the performance of the catalyst in the catalyst storage82caused by a decrease in the temperature of the catalyst resulting from the accumulation of the condensed water is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the upper end of the catalyst storage82and the upper end of the water lock84are located below the upper end of the engine5in the side view. Furthermore, the lower end of the catalyst storage82and the lower end of the water lock84are located above the lower end of the engine5in the side view. Thus, an increase in the size of the watercraft body2in the vertical direction is significantly reduced or prevented as compared with the case where the upper ends of the catalyst storage82and the water lock84are located below the lower end of the engine5or the lower ends of the catalyst storage82and the water lock84are located above the upper end of the engine5.

According to a preferred embodiment of the present invention, the catalyst storage82overlaps with the first exhaust pipe81in the side view. Thus, the catalyst storage82and the first exhaust pipe81are located close to each other, and hence the length of the first exhaust pipe81is reduced. Consequently, an increase in the weight of the first exhaust pipe81is significantly reduced or prevented. Thus, an increase in the weight of the watercraft body2is significantly reduced or prevented.

According to a preferred embodiment of the present invention, the portion82bof the side surface of the catalyst storage82and the portion81hof the side surface of the first exhaust pipe81are integral and unitary with each other. Thus, the catalyst storage82is located close to the exhaust ports56b, and hence an increase in the size of the watercraft body2in the width direction is further significantly reduced or prevented. Furthermore, according to a preferred embodiment of the present invention, the catalyst storage82and the first exhaust pipe81are located close to each other, and hence the length of the first exhaust pipe81is further reduced such that an increase in the weight of the first exhaust pipe81is further significantly reduced or prevented. Consequently, an increase in the weight of the watercraft body2is further significantly reduced or prevented.

The preferred embodiments of the present invention described above are illustrative in all points and not restrictive. The extent of the present invention is not defined by the above description of the preferred embodiments but by the scope of the claims, and all modifications within the meaning and range equivalent to the scope of the claims are further included.

For example, while the engine preferably includes the plurality of (for example, three) exhaust ports in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the engine may alternatively include one exhaust port or a number of exhaust ports other than three.

While the engine is preferably an in-line engine in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the engine may alternatively be a V-type engine, or an engine other than an in-line engine and a V-type engine.

While the first exhaust pipe preferably totally overlaps with the side surface of the engine in the side view in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the first exhaust pipe may not totally overlap with the side surface of the engine in the side view. In other words, the first exhaust pipe may partially overlap with the side surface of the engine in the side view.

While the catalyst storage preferably totally overlaps with the side surface of the engine in the side view in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the catalyst storage may not totally overlap with the side surface of the engine in the side view. In other words, the catalyst storage may only partially overlap with the side surface of the engine in the side view.

While the second exhaust pipe preferably partially overlaps with the side surface of the engine in the side view in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the second exhaust pipe may alternatively totally overlap with the side surface of the engine in the side view, or the second exhaust pipe may not overlap with the side surface of the engine in the side view.

While the catalyst storage is preferably located forward relative to the rearward most exhaust port of the plurality of exhaust ports and rearward relative to the forward most exhaust port of the plurality of exhaust ports in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the catalyst storage may not be located forward relative to the rearward most exhaust port of the plurality of exhaust ports and rearward relative to the forward most exhaust port of the plurality of exhaust ports so far as the catalyst storage overlaps with the engine in the side view.

While the first exhaust pipe and the catalyst storage are preferably integral and unitary with each other in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the first exhaust pipe and the catalyst storage may alternatively be provided separately from each other. When the first exhaust pipe and the catalyst storage are provided separately from each other, the first exhaust pipe and the catalyst storage may be connected to each other by a connecting member such as a bolt, for example. Alternatively, the first exhaust pipe, the catalyst storage, and the second exhaust pipe may be connected to each other by clamping the catalyst storage between the first exhaust pipe and the second exhaust pipe.

While the first exhaust pipe preferably includes the lead-out portion, the bent portion, and the increased diameter portion, and the lead-out portion, the bent portion, and the increased diameter portion are preferably integral and unitary with each other in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the lead-out portion, the bent portion, and the increased diameter portion may not be integral and unitary with each other. For example, the lead-out portion and the bent portion may be integral and unitary with each other, and the increased diameter portion may be separately provided. Alternatively, the lead-out portion, the bent portion, and the increased diameter portion may be provided separately from each other. When the lead-out portion, the bent portion, and the increased diameter portion are provided separately from each other, the lead-out portion, the bent portion, and the increased diameter portion may be connected to each other by connecting members such as bolts, for example.

While the first exhaust pipe preferably includes the lead-out portion, the bent portion, and the increased diameter portion in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the first exhaust pipe may not include the bent portion and the increased diameter portion so far as the same includes the lead-out portion connected to the exhaust ports. For example, the first exhaust pipe may include the lead-out portion and the bent portion without including the increased diameter portion, or may include the lead-out portion and the increased diameter portion without including the bent portion. Alternatively, the first exhaust pipe may include only the lead-out portion.

While the portion (i.e., the right portion of the catalyst storage) of the side surface of the catalyst storage and the portion (i.e., the left portion of the trunk of the first exhaust pipe) of the side surface of the first exhaust pipe are preferably integral and unitary with each other in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the side surface of the catalyst storage and the side surface of the first exhaust pipe may not be integral and unitary with each other, but may be separate from each other.

While the bottom of the exhaust gas passage of the catalyst storage is preferably located at the same or substantially the same height as the bottom of the exhaust gas passage of the first exhaust pipe, the bottom of the exhaust gas passage of the second exhaust pipe is preferably located at the same or substantially the same height as the bottom of the exhaust gas passage of the catalyst storage, and the bottom of the exhaust gas passage of the water lock is preferably located at the same or substantially the same height as the bottom of the exhaust gas passage of the second exhaust pipe in a preferred embodiment described above, the present invention is not restricted to this. According to a preferred embodiment of the present invention, the bottom of the exhaust gas passage of the catalyst storage may alternatively be located below the bottom of the exhaust gas passage of the first exhaust pipe. Furthermore, the bottom of the exhaust gas passage of the second exhaust pipe may alternatively be located below the bottom of the exhaust gas passage of the catalyst storage. In addition, the bottom of the exhaust gas passage of the water lock may alternatively be located below the bottom of the exhaust gas passage of the second exhaust pipe.