JPH11278387A - Water penetration preventing device for internal combustion engine in ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently maintain smooth drive of an internal combustion engine and purifying performance based on a catalyst arranged in an exhaust pipe by preventing reverse flow of water in an exhaust passage inside the exhaust pipe in the case of propulsion or capsize of a ship. SOLUTION: An extension end of an exhaust pipe 35 extended from an internal combustion engine 16 is connected to a water lock device 36, which is connected to the outside of a hull 3 through another exhaust pipe 37. The exhaust pipe 35 is divided in its longitudinal middle part into an upstream side pipe 42 and a downstream pipe 43. To an air box 44 arranged between respective division ends of the upstream and downstream pipes 42, 43, the respective division ends are connected. The division end of the upstream pipe 42 is opened in the vertical directional midway part inside the air box 44. Water 2 is supplied to an exhaust passage 47 inside at least one of the downstream pipe 43 of the exhaust pipe 35, the water lock device 36, and another exhaust pipe 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing water such as seawater from entering an internal combustion engine through an exhaust system member of the internal combustion engine mounted on a hull. It is about.

[0002]

2. Description of the Related Art Conventionally, a watercraft has an internal combustion engine mounted on a hull as a propulsion device, and an exhaust pipe extending from the internal combustion engine is provided, and an extended end of the exhaust pipe communicates with a water lock device. In some cases, another exhaust pipe is provided for connecting the water lock device to the outside of the hull.

[0003] In the above case, the water lock device prevents water such as seawater flowing into the other exhaust pipe from going toward the exhaust pipe when the boat is propelled or capsized. Water is prevented from flowing back through the exhaust pipe and entering the internal combustion engine.

[0004]

If the operation of the boat at the time of propulsion or the operation of the boat at the time of capsizing is large, the water passes through the water lock device and flows backward through the exhaust pipe. And may get into the internal combustion engine. As described above, when water enters the internal combustion engine, smooth driving of the internal combustion engine thereafter is hindered.

On the other hand, it is conceivable to provide a catalyst inside the exhaust pipe in order to purify the exhaust gas. However, if the water flows back and adheres to the catalyst as described above, the catalyst There is a problem that the purification performance is reduced and the deterioration is advanced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and prevents water from flowing backward through an exhaust passage inside an exhaust pipe when a boat is propelled or capsized, so that an internal combustion engine can be smoothly operated. It is an object of the present invention to ensure that the drive performance and the purification performance of the catalyst provided in the exhaust pipe are kept good.

[0007]

A device for preventing water from entering an internal combustion engine for marine vessels according to the present invention for solving the above problems is as follows.

According to the first aspect of the present invention, an exhaust pipe 35 extending from the internal combustion engine 16 mounted on the hull 3 is provided, and an extended end 35a of the exhaust pipe 35 is communicated with a water lock device 36 and the water lock device 36 is provided. The lock device 36 is connected to the hull 3
In a device for preventing water from entering an internal combustion engine for boats provided with another exhaust pipe 37 communicating with the outside of the

(1) The exhaust pipe 35 is divided at an intermediate portion in the longitudinal direction and is constituted by an upstream pipe 42 and a downstream pipe 43, and the divided ends 42a of the upper and lower pipes 42, 43 are formed. ,
An air box 44 is interposed between the air boxes 43a.
The divided ends 42a and 43a are connected to each other, and the divided end 42a of the upstream pipe 42 is opened at a vertically intermediate portion inside the air box 44,

(2) The water 2 is supplied to an exhaust passage 47 in at least one of the downstream pipe 43 of the exhaust pipe 35, the water lock device 36, and at least one of the other exhaust pipes 37.

According to a second aspect of the present invention, in addition to the first aspect, a catalyst 5 for purifying the exhaust gas 19 is provided inside the upstream pipe 42.
1 is provided.

The invention according to claim 3 is the invention according to claim 1 or 2
In addition, the air box 44 is disposed below the exhaust port 16f formed in the cylinder head 16d of the internal combustion engine 16, and the upstream pipe 42 is connected to the exhaust port 16f from the exhaust port 16f side. It extends downward from the port 16f, and its divided end 42a is connected to the air box 44.
It is connected to.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1 to FIG. 6, reference numeral 1 denotes a straddle-type (in other words, saddle-ride type) small boat which floats on water 2 in the sea or the like. The arrow Fr indicates the boat 1
The left and right described below refer to the width direction of the hull 3 of the boat 1 toward the front.

The boat 1 is a planing-type small boat,
In other words, the boat 1 is capable of high-speed propulsion so as to slide on the water 2 surface in a substantially constant posture with a small inclination angle with respect to the water 2 surface. The hull 3 of the boat 1 is made of resin reinforced with fiber (FRP),
The upper part is a deck 5, and the joint between the hull 4 and the deck 5 is a gunnel 6. A hull liner 7 is connected to the inner surface of the hull 4, whereby the hull 4 is sufficiently reinforced.

A front wall 8 and a rear wall 9 for dividing the interior of the hull 3 into a plurality of rooms in the front-rear direction are provided. The front wall 8 and the rear wall 9 are provided on the inner surfaces of the hull 4 and the deck 5, respectively. The hull 3 is reinforced by being firmly connected. Hull 3 above
Inside the front chamber 1, the front side of the front wall 8
0, an intermediate room 11 which is an engine room between the front wall 8 and the rear wall 9, and a rear room 12 behind the rear wall 9.
It has been. A communication passage 13 is formed in the front wall 8 to allow the front chamber 10 and the intermediate chamber 11 to communicate with each other.
Another communication path 14 is formed in the rear wall 9 to allow the intermediate chamber 11 and the rear chamber 12 to communicate with each other.

A propulsion device 15 mounted on the hull 3 for propelling the hull 3 is provided. This propulsion device 1
Reference numeral 5 denotes a four-cycle three-cylinder internal combustion engine 16 housed in the intermediate chamber 11 and supported by the hull liner 7 via a cushioning material, and the internal combustion engine 16 installed in the front chamber 10.
A fuel tank 17 for storing fuel to be supplied to the internal combustion engine 16, and air outside the internal combustion engine 16 and the fuel
System member 18 that can be supplied to the internal combustion engine 16
The combustion gas of the fuel burned in the hull 3
And an exhaust system member 20 for discharging the gas to the outside. Before the air outside the hull 3 is introduced into the hull 3, rear air introduction pipes 21 and 21 are provided.

The internal combustion engine 16 includes a crankcase 16a supported by the hull 4, a crankshaft 16b supported by the crankcase 16a and rotatable around an axis extending in the front-rear direction of the hull 3. Crankcase 1
Cylinder block 16c projecting upward from 6a
A cylinder head 16d attached to the protruding end of the cylinder block 16c;
Cylinder head cover 16 attached to the upper surface of 6d
e, and an exhaust port 16f is formed in the cylinder head 16d for each cylinder.

The propulsion device 15 is provided with jet injection means 22 driven by receiving power from the internal combustion engine 16 to propel the hull 3. This jet injection means 2
2 is supported by the rear of the hull 4 and has a front end of the hull 3
A water pipe 23 is opened downward at the rear of the hull 3 and has a rear end opened toward the rear of the hull 3. This running water pipe 2
Reference numeral 3 has a circular cross section, and its inside is a water passage 24 for communicating the lower part of the rear part of the hull 3 with the rear of the hull 3. An impeller 25 is provided at a rear portion of the water passage 24 and supported by the water pipe 23. The impeller 25 is connected to the internal combustion engine 16 by a propulsion shaft 28.

A steering pipe 30 which is fitted to the rear end of the water pipe 23 and is supported at the rear of the hull 3 is provided. The steering pipe 30 is supported so that its rear part can be turned up and down and left and right. I have. On the other hand, a steering handle 31 is protruded from the front upper portion of the hull 3 and the steering pipe 30 is attached to the handle 31.
Are linked together. Behind the handle 31, a straddle-type seat 32 is provided on the upper surface of the hull 3, and is provided at an end of the handle 31 by a driver sitting in a straddle shape on the seat 32 toward the front. Grip 3
1a can be gripped.

When the internal combustion engine 16 is driven, the air outside the internal combustion engine 16 passing through the intake system member 18 and the fuel supplied from the fuel tank 17 are mixed with the internal combustion engine 1.
The heat energy is supplied to the fuel cell 6 for combustion, and the heat energy is converted into power and output. The combustion gas generated by the combustion passes through the exhaust port 16f as the above-mentioned exhaust gas 19 and is discharged outside the hull 3 through the exhaust system member 20.

The power output from the internal combustion engine 16 is transmitted to the propulsion shaft 28 of the jet injection means 22 as described above, and the water 2 in the water passage 24 is removed by the impeller 25 rotating with the propulsion shaft 28. It is accelerated rearward, whereby water 2 below the rear part of the hull 3 is sucked into the water passage 24 from the front end of the water passage 24, while passing through the water passage 24 from the rear end. The boat 1 is jetted rearward, and the boat 1 is propelled forward by the reaction force of the jet.

During the propulsion, the driver operates the steering wheel 31.
Is operated to rotate the steering pipe 30 so as to change the attitude of the steering pipe 30, the direction of the injection changes, and the boat 1 is steered in a desired direction.

The exhaust system member 20 is connected to the internal combustion engine 16.
Exhaust port 16f formed in the cylinder head 16d
An exhaust pipe 35 extending from the side, a water lock device 36 connected to an extension end 35a of the exhaust pipe 35, and a water lock device 36 extending from the water lock device 36 and communicating with the outside of the hull 3. An exhaust pipe 37 is provided, and an upstream end of the exhaust pipe 35 is connected to the cylinder head 16d. The water lock device 36
Is formed by a closed air box 38, which is fitted into a recess 39 formed in the hull liner 7 and supported by the hull liner 7 by fasteners.

The extended end 35a, which is the downstream end of the exhaust pipe 35, is connected to the air box 38 of the water lock device 36.
And the upstream end 37a of the other exhaust pipe 37 is closer to the inside of the air box 38 of the water lock device 36 than the opening of the extension end 35a. It is open on the upper side. Water 2 is stored in the inner bottom of the air box 38. The other exhaust pipe 37 is made of a flexible elastic rubber pipe whose main body is a cushioning material, whereby the transmission of the vibration of the internal combustion engine 16 to the hull 3 is mitigated.

The exhaust pipe 35 is divided at an intermediate portion in the longitudinal direction, and is constituted by an upstream pipe 42 and a downstream pipe 43. Each of the divided ends 42 of the upstream pipe 42 and the downstream pipe 43 is separated.
a, 43a is provided so that an air box 44 having a sealed inside is interposed therebetween, and this air box 44 is fitted into a concave portion 46 formed in the hull liner 7, and is fastened to the hull liner 7 by a fastener. Supported.

The divided end 42a of the upstream pipe 42 is connected to the air box 44 by a flexible elastic rubber joint pipe 45 serving as a cushioning material. It is opened in the middle part in the vertical direction. Further, the divided end 43a of the downstream pipe 43 is also opened at an intermediate portion in the vertical direction inside the air box 44, and the opening of the divided end 43a is divided into the upstream pipe 42. It is located below the end 42a.

The upstream pipe 42 of the exhaust pipe 35, the joint pipe 45, the air box 44, and the downstream pipe 4 of the exhaust pipe 35
3. The inside of the air box 38 of the water lock device 36 and the inside of each of the other exhaust pipes 37 have an exhaust passage 4 communicating with each other.
The exhaust gas 19 from the internal combustion engine 16 is discharged into the water 2 outside the hull 3 through the exhaust passage 47.

In particular, as shown in FIGS. 2, 3, and 7, the air box 44 is provided with the cylinder head 16 of the internal combustion engine 16.
It is disposed below the exhaust port 16f formed at the point d. The upstream pipe 42 is connected to the exhaust port 16.
f side to the lower side than the exhaust port 16f, and the divided end 42a is connected to the air box 4 as described above.
4.

An exhaust cooling device 49 for cooling the exhaust system member 20 with water 2 is provided. The exhaust cooling device 49 includes the upstream pipe 42, the joint pipe 45,
A water jacket 50 is formed on each of the air box 44 and the downstream pipe 43, and these water jackets 50 are communicated with each other. Water 2 for cooling is supplied to the water jacket 50 at the upstream end of the upstream pipe 42, and the water 2 passes through the water jacket 50 and passes through the upstream pipe 42 and the like. This cooling directly cools and indirectly cools the exhaust gas 19 passing through the exhaust passage 47 such as the upstream pipe 42 by this cooling.

After the cooling, the water 2 is supplied to an exhaust passage 47 inside the air box 38 of the water lock device 36. That is, the exhaust gas 19 passing through the exhaust passage 47
The water 2 is directly supplied to the exhaust gas 19 and the exhaust gas 19 is directly cooled. After that, the water 2 and the exhaust 19 are transferred to another exhaust pipe 3.
It is discharged to the outside of the hull 3 through 7. The above-described cooling prevents the other exhaust pipe 37 and the joint pipe 45 from being deteriorated by the exhaust heat.

According to the above-described structure, the exhaust pipe 35 is divided at an intermediate portion in the longitudinal direction so that the upstream pipe 42 and the downstream pipe 43 are separated.
And an air box 44 for connecting the divided ends 42a, 43a of the upper and lower pipes 42, 43 is provided.
A divided end 42 a of the upstream pipe 42 is opened at a middle part in the vertical direction inside the air box 44.

For this reason, it is assumed that the water 2 flows backward from the other exhaust pipe 37 through the water lock device 36 through the exhaust pipe 47 inside the downstream pipe 43 during the propulsion operation of the boat 1. The water 2 is stored in the inner bottom of the air box 44. Further, even if the water 2 flows through the water lock device 36 from the other exhaust pipe 37 side and flows backward through the exhaust passage 47 of the downstream pipe 43 in the operation when the boat 1 is overturned, , The air box 44 in the overturned state
(Indicated by a two-dot chain line in FIG. 6). That is, the water 2 is prevented from flowing backward through the exhaust passage 47 of the upstream pipe 42 from the water lock device 36 toward the internal combustion engine 16.

Therefore, the water 2 is prevented from entering the internal combustion engine 16, so that
Is smoothly maintained.

Since the water 2 is directly supplied to the exhaust passage 47 in the air box 38 of the water lock device 36,
The exhaust gas 19 passing through the exhaust passage 47 is more reliably cooled by the water 2, so that when the exhaust gas 19 is discharged to the outside of the hull 3, the other exhaust pipe 37 is deteriorated by the exhaust heat. Is prevented.

In the above case, since the water 2 is supplied to the downstream side of the exhaust gas 19 from the air box 44, the back flow of the water 2 toward the upstream pipe 42 is as described above. Similarly, it is prevented by the air box 44.

In FIG. 6, a catalyst 51 for purifying the exhaust gas 19 is provided inside the divided end 42a of the upstream pipe 42,
The catalyst 51 is a three-way catalyst.

In the above case, as described above, the upstream pipe 4
Since the water 2 does not flow backward through the second exhaust passage 47, the water 2 is prevented from adhering to the catalyst 51.

Therefore, the purification performance of the catalyst 51 is kept good, and the progress of deterioration is prevented, which is beneficial for the life of the catalyst.

As described above, the air box 44 is disposed below the exhaust port 16f formed in the cylinder head 16d of the internal combustion engine 16, and the upstream pipe 42 is connected to the exhaust port 16f side. This exhaust port 1
6f.
a is connected to the air box 44.

Therefore, the upstream pipe 42 and the air box 44
Are both located below the exhaust port 16f of the cylinder head 16d of the internal combustion engine 16, that is,
The exhaust system member 20 disposed around the internal combustion engine 16 is positioned low, so that the center of gravity of the boat 1 is reduced and a stable propulsion state is obtained.

Here, since the air box 44 is located below the exhaust port 16f as described above, if water 2 accumulates in the air box 44, the boat 1 may be overturned. , The water 2 inside the air box 44 is
May flow back to the internal combustion engine 16 through the exhaust passage 47.

However, as described above, the water 2 is supplied to the exhaust passage 47 through the downstream pipe 43, the water lock device 36, and the like, which are downstream of the air box 44 and the exhaust 19. The accumulation of the water 2 inside the air box 44 is prevented beforehand. Also, if the air box 44
Even if the water 2 accumulates in the inside of the air box 44, as described above, the divided end 42a of the upstream pipe 42 is opened in the middle of the air box 44 in the vertical direction. Therefore, when the boat 1 is overturned, the water 2 in the air box 44 is prevented from flowing back to the internal combustion engine 16 side.
The smooth driving of the internal combustion engine 16 is kept good.

Further, the upstream pipe 42 is located above the waterline at the time of capsize, so that the backflow of the water 2 in the exhaust passage 47 of the upstream pipe 42 is more reliably prevented. .

As described above, both air boxes 38, 4
4 is supported by the integrally formed hull liner 7 and furthermore, is supported in a state of being fitted and positioned in the concave portions 39 and 46 formed in the hull liner 7. 44 can be easily attached to the hull 3 and the assembling accuracy is improved.

Further, since the hull liner 7 for reinforcing the hull 4 is used for supporting the air boxes 38 and 44, the use of the air boxes 38 and 44 can be achieved with a simple structure by the use of the hull liner 7. , Is strongly supported.

The upstream pipe 42 of the exhaust pipe 35 is
Immediately after extending from the internal combustion engine 16, it is bent downward. Therefore, the exhaust passage 4 of the upstream pipe 42
7 is more reliably prevented from flowing back through the water 2.

In FIG. 7, the water jacket 50 of the upstream pipe 42 communicates with the water jacket 50 of the air box 44, and lower communication passages 44a, 44b and 44c are provided. The communication passage 44 b is formed so that the water 2 in the water jacket 50 of the upstream pipe 42 naturally flows down toward the water jacket 50 of the air box 44. For this reason,
When the internal combustion engine 16 is stopped, the air box 44 passes from the water jacket 50 of the upstream pipe 42 through the communication passage 44b.
The water 2 naturally flows down into the water jacket 50 of the water lock device 36, and further, the water 2 naturally flows down into the air box 38 of the water lock device 36 through the exhaust passage 47 of the downstream pipe 43. The water 2 in the water jacket 50 of the side pipe 42
Is not allowed to accumulate.

The communication passage 44c is connected to the upstream pipe 42.
The air rising to the upper part of the water jacket 50 at the divided end 42 a of the air box 44 is formed to escape into the water jacket 50 of the air box 44.
It is supposed that air does not remain at the top of the car.

The opening position of the divided end 43a of the downstream tube 43 with respect to the air box 44 is substantially the same as the opening of the divided end 42a of the upstream tube 42, or , May be above this opening.
The water 2 may be supplied from the water jacket 50 to the exhaust passage 47 to the downstream pipe 43, the air box 44, or to the exhaust passage 47 of another exhaust pipe 37. Water 2 may be supplied to the passages 47 directly to the exhaust passages 47 without passing through the water jackets 50.

FIGS. 7 and 8 show another embodiment.

According to this, the downstream pipe 43 is made of a flexible elastic rubber pipe, and the water 2 after passing through the water jacket 50 is supplied to the exhaust passage 47 of the downstream pipe 43. Thus, deterioration of the downstream pipe 43 due to exhaust heat is prevented.

Since other configurations and operations are the same as those of the above-described embodiment, the same reference numerals are given to the drawings and the description thereof will be omitted.

[0054]

The effects of the present invention are as follows.

According to a first aspect of the present invention, an exhaust pipe extending from an internal combustion engine mounted on a hull is provided, and an extending end of the exhaust pipe is communicated with a water lock device. In a device for preventing water from entering into a marine internal combustion engine provided with another exhaust pipe communicating with the outside,

(1) The exhaust pipe is divided into an upstream pipe and a downstream pipe by dividing the exhaust pipe at an intermediate portion in the longitudinal direction.
An air box is interposed between the divided ends of the downstream pipe, the divided ends are connected to the air box, and the divided end of the upstream pipe is halfway in the vertical direction inside the air box. It is open to the part.

For this reason, even if the water flows from the other exhaust pipe side through the water lock device and flows back through the exhaust passage inside the downstream pipe during the propulsion operation of the boat, It is stored in the inner bottom of the air box. In addition, even when the water passes through the water lock device from the other exhaust pipe side and flows backward through the exhaust passage of the downstream pipe in the operation at the time of capsizing of the boat, this water also becomes It is stored in the inner bottom of the air box. That is, the water is prevented from flowing backward through the exhaust passage of the upstream pipe from the water lock device toward the internal combustion engine.

Therefore, since the water is prevented from entering the internal combustion engine, the smooth driving of the internal combustion engine is favorably maintained.

(2) Water is supplied to an exhaust passage inside at least one of the downstream pipe of the exhaust pipe, the water lock device, and at least one of the other exhaust pipes.

Therefore, the exhaust gas passing through the exhaust passage is more reliably cooled by the water, so that when the exhaust gas is discharged to the outside of the hull, the downstream pipe and the like are temporarily made of rubber cushioning material. Even if there is, it is possible to prevent the downstream pipe and the like from being deteriorated by the exhaust heat, which is beneficial for the life of the exhaust system member.

In the above case, since the water is supplied to the downstream side of the exhaust gas from the air box, the flow of the water back toward the upstream pipe is, as described above,
This is prevented by the air box, so that the smooth driving of the internal combustion engine is favorably maintained.

According to a second aspect of the present invention, an exhaust gas purifying catalyst is provided inside the upstream pipe.

For this reason, as described above, when a catalyst is provided to purify exhaust gas, water does not flow backward in the exhaust passage of the upstream pipe as described above, so that water adheres to the catalyst. That is prevented.

Therefore, the purification performance of the catalyst is kept good, and the progress of deterioration is prevented, which is beneficial for the life of the catalyst.

According to a third aspect of the present invention, the air box is disposed below an exhaust port formed in a cylinder head of the internal combustion engine, and the upstream pipe is connected to the exhaust port from the exhaust port side. Also extends downward, and its divided end is connected to the air box.

For this reason, both the upstream pipe and the air box are located below the exhaust port of the cylinder head of the internal combustion engine, that is, the exhaust system member disposed around the internal combustion engine is low. As a result, the center of gravity of the boat is reduced and a stable propulsion state is obtained.

Here, as described above, since the air box is located below the exhaust port, if water accumulates inside the air box, when the boat overturns, the air box is closed. There is a possibility that the water inside flows back to the internal combustion engine through the exhaust passage of the exhaust pipe.

However, as described above, the water is supplied to the exhaust passage through a downstream pipe, a water lock device, or the like, which is downstream of the exhaust from the air box. The accumulation of water is prevented beforehand. Further, even if water accumulates in the air box, as described above, the divided end of the upstream pipe is opened at a middle part in the vertical direction in the air box. Therefore, at the time of capsizing of the boat, the water inside the air box is prevented from flowing back to the internal combustion engine side, and thus, while the center of gravity of the boat is lowered, as described above. In addition, smooth driving of the internal combustion engine is favorably maintained.

[Brief description of the drawings]

FIG. 1 is a plan partial sectional view of a boat.

FIG. 2 is a side sectional view of the boat.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2;

FIG. 6 is a partially enlarged sectional view of FIG. 1;

FIG. 7 is an overall simplified diagram of the present apparatus in another embodiment.

FIG. 8 is a partial view taken along line 8-8 of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boat 2 Water 3 Hull 15 Propulsion device 16 Internal combustion engine 16d Cylinder head 16f Exhaust port 19 Exhaust 20 Exhaust system member 35 Exhaust pipe 35a Extension end 36 Water lock device 37 Other exhaust pipe 37a Upstream end 42 Upstream pipe 42a Split end 43 Downstream pipe 43a Split end 44 Air box 47 Exhaust passage 51 Catalyst

Claims (3)

[Claims] An exhaust pipe extending from an internal combustion engine mounted on a hull is provided, and an extended end of the exhaust pipe communicates with a water lock device, and the water lock device communicates with the outside of the hull. (1) The exhaust pipe is divided into an upstream pipe and a downstream pipe by dividing the exhaust pipe at a middle part in a longitudinal direction thereof. An air box is interposed between the divided ends of the downstream pipe, and the divided ends are connected to the air box, and the divided end of the upstream pipe is arranged in the vertical direction inside the air box. (2) An internal combustion engine for a marine vessel which is configured to supply water to an exhaust passage inside at least one of a downstream pipe of the exhaust pipe, a water lock device, and another exhaust pipe. Water entry prevention device. 2. The apparatus for preventing water from entering an internal combustion engine for marine vessels according to claim 1, wherein a catalyst for purifying exhaust gas is provided inside the upstream pipe. 3. The air box is disposed below an exhaust port formed in a cylinder head of the internal combustion engine, and the upstream pipe is directed from the exhaust port side to below the exhaust port. 3. The device for preventing water from entering an internal combustion engine for marine vessels according to claim 1, wherein the end is extended and the divided end is connected to the air box.