JPH0853098A - Small-sized planing boat - Google Patents

Abstract

PURPOSE:To properly arrange a four-cycle engine considerably larger than a conventionally mounted two-cycle in a small space inside a hull. CONSTITUTION:A four-cycle engine 20 is mounted so that a crankshaft is directed toward the left and right sides of a hull, and the crankshaft is connected with a rear propulsion means 50 through a pair of bevel gears. All the cylinders 25 of the engine 20 are tilted to the rear part of the hull, and the intake system equipment 10 is arranged in the upper part of the engine 20 including the tilted cylinder 25, and the exhaust system equipment 60 is arranged at the position bwhind the hull in comparison with the engine 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small planing boat, and more particularly to a small planing boat equipped with a 4-cycle engine.

[0002]

2. Description of the Related Art A small planing boat is a small vehicle that glides on the water as if it were a motorcycle. Water jet pumps and screws are used as propulsion means, and the engine for driving them is the space surrounded by so-called hull skins such as the bottom hull and hood or seat along with the intake and exhaust systems. It is installed in.
If the engine, etc. appears below the bottom hull, it will not be able to run smoothly, and even if the engine, etc. appears above or to the side of the hood or water, the engine etc. will be directly splashed with water and combustion will be hindered. This is because rust is likely to occur and it is difficult for people to ride.

However, in the small planing boat, the space where the engine is installed (that is, the engine room)
Are generally quite limited in their volume. If the volume is too large, the small planing boat itself tends to be large, and the peculiar motion characteristics such as speed and turning characteristics tend to deteriorate, and if the seat width is increased, it becomes difficult to ride across it. .

Therefore, conventionally, a two-cycle engine has been used as a propulsion engine for a small planing boat. Two
The cycle engine is compact because it does not have an oil pan, valve, valve mechanism, etc., and because it has a high output due to the frequency of explosions, it is extremely suitable for small planing boats.

An example in which a two-cycle engine is mounted on a small planing boat is described in, for example, Japanese Utility Model Laid-Open No. 3-61152.

[0006]

In recent years, from the viewpoint of preventing noise and air pollution, the possibility of using a 4-cycle engine for small-sized planing boats has begun to be examined.

However, since the 4-cycle engine is larger than the 2-cycle engine having the same output,
In order to mount it on a small planing boat as a propulsion engine, how to arrange it in the space inside the hull becomes an issue. The problem is difficult to be solved easily due to the following circumstances. In other words, a) The engine room of a small planing boat is limited in volume as it would be if it had a two-cycle engine.

(B) The 4-cycle engine is larger than the 2-cycle engine, and the intake system equipment such as the intake silencer and the carburetor satisfy a certain condition with respect to the engine and are not separated from each other. There is a constraint that they must be placed (the same relationship as in the case of a 2-cycle engine). That is, a large 4-cycle engine must be housed in the engine room as a larger block that is almost integrally connected to the intake system equipment. In addition, the reason why the 4-cycle engine becomes large is that a large space is indispensable on the cylinder because it is equipped with intake and exhaust valves (mushroom valve).
As long as a wet sump lubrication method that collects oil in the crankcase is adopted, following the example of a general 4-cycle engine, a space for an oil pan is required at the bottom, and the explosion frequency is higher than that of the 2-cycle engine. Since it is small, it is necessary to increase the number of cylinders and the displacement in order to make the output equivalent. In addition, it is necessary to connect the intake system equipment to the engine almost integrally because, for efficiency reasons, those equipment (especially carburetor) must be connected to the cylinder so that fuel particles enter the combustion chamber without countering gravity. Should also be above, and they should be placed close to the cylinder in the sense of reducing intake resistance.

C) Since the 4-cycle engine also exceeds the 2-cycle engine in terms of weight, it is necessary to give sufficient consideration to weight distribution in a small planing boat. In other words, in order to balance and stabilize a small planing boat, the engine must be placed at an appropriate position in the front, rear, left and right directions of the hull. The space where the engine can be mounted is generally narrow in the width direction (left and right), and the installation position of the engine is restricted in that direction, so it is not easy to prevent the weight of the engine from being biased to the left or right of the hull. .

D) As for the propulsion means of a small planing boat such as a water jet pump or a screw, the drive shaft is provided near the bottom of the hull, whereas the 4-cycle engine has an oil pan. The crankshaft is generally higher than in the case of a two-cycle engine (position that is upward from the bottom of the engine)
It is in. Therefore, depending on the amount of oil stored in the oil pan and the shape of the oil pan and crankcase,
It is also conceivable that the position of the crankshaft may be too high to be directly connected to the drive shaft of the propulsion means, or the drive shaft may be forced to have an unnecessary angle.

An object of the present invention is to solve the above problems and to provide a small planing boat equipped with a four-cycle engine in a preferable arrangement.

[0012]

The small planing boat of the present invention comprises:
A 4-cycle engine is installed in the space surrounded by the hull skin. A) A 4-cycle engine is installed so that the crankshaft faces the left and right of the hull, and the crankshaft is replaced with a bevel gear pair (paired). Bevel gears, including those connected to other gears) and connected to the rear propulsion means via
b) All cylinders of the 4-cycle engine were tilted to the same side either before or after the hull, and the intake system or exhaust system equipment was placed above the engine including the tilted cylinders.
Things.

Particularly, in this small planing boat, as described in claim 2, c) all cylinders of the four-cycle engine are tilted rearward of the hull, and an intake system device is arranged above them, and the four-cycle Exhaust system equipment should be placed at a position behind the hull of the engine.

Further, as described in claim 3, d) the crankshaft,
It is advisable to connect to (the drive shaft of) the propulsion means via the above-mentioned bevel gear pair, another gear pair, and a transmission shaft arranged rearward and below the crankshaft.

[0015]

In the small planing boat of the present invention, the bottom hull and hood
Small volume space surrounded by seats (engine room)
Among them, a 4-cycle engine and the like are properly arranged as follows.

1) A four-cycle engine and its associated intake / exhaust system equipment are compactly housed in the above space of the hull. This can be explained as follows. The intake system equipment should be placed adjacent to the cylinder because it should be placed in the above-mentioned integral relationship with the engine, and in the case of multiple cylinders, it should be placed at an adjacent position along the arrangement of the cylinders. Is normal. Therefore, when placing the engine so that the crankshaft faces the front and rear of the hull in the above space (so-called vertical installation), the intake system is placed in the space to the right or left of the cylinders aligned in the front-rear direction along the crankshaft. Equipment will be put. However, because the 4-cycle engine is taller than the 2-cycle engine, if the engine oriented in the above direction is placed almost in the center of the hull width, the hull is particularly limited in the width (left and right) direction. The inner space is divided into left and right, and there is no solid space where the intake system equipment can be placed. Further, if the engine is placed closer to the left or right of the hull, it is usually difficult to balance the left and right weight of the hull because the 4-cycle engine is heavy. On the other hand, in this small planing boat, the crankshaft is directed to the left and right of the hull (therefore, the cylinders are also aligned in that direction) as described in a) above, and is placed in the so-called horizontal position.
Since it is equipped with a cycle engine, it is not necessary to install equipment such as the intake system in a narrow space to the right or left of the engine.
It may be provided at a position facing the arrangement of the cylinders arranged side by side. Therefore, it is sufficient for the width of the engine room to have a size that allows the four-cycle engine to be placed horizontally, and it is not necessary to have a size that allows the intake system device to be arranged to the right or left of the width. Since the above-mentioned space, which is the engine room, is usually long in the front-back direction of the hull, the intake system and exhaust system devices, etc. are located in front or behind the cylinder array surface of the engine placed horizontally. It can be placed relatively easily behind.

2) In this small planing boat, the 4-cycle engine can be mounted at a preferable position in terms of weight balance between the left and right and the front and rear of the hull. This is because it is not necessary to move the engine to either the left or right side of the hull as described above in relation to the intake system equipment, and the space for mounting the engine is usually long in the front-rear direction as described above. This is because the engine can be placed in a relatively free position.

3) Even though the engine is placed horizontally and the crankshaft is directed to the left and right of the hull as described above, the rotation of the crankshaft is smoothly transmitted to the propulsion means at the rear of the hull. This is because the bevel gear pair described in a) above transmits power from the crankshaft to the drive shaft of the propulsion means arranged at a right angle (or almost right angle). Since power can be transmitted to the rear of the hull in this manner, it is also possible to use a water jet pump, a screw, or the like as the propulsion means similar to the conventional one in a preferable mode.

4) As described in b) above, all cylinders of the engine are tilted, and in order to suppress the height of the 4-cycle engine, which is supposed to be quite tall, the center of gravity of the small planing boat is set at a low position, The stability can be improved.

5) Since the intake system or exhaust system equipment is arranged on the upper part of the engine in which the cylinder is tilted to be short, the space required in the longitudinal direction of the hull as an engine room is almost expanded. There is nothing to do. In other words, if the cylinder stands upright and the intake and exhaust devices are distributed to the front or rear of it (the 4-cycle engine is tall, so if the cylinder is set up, the space for placing any device above it) However, if you place any of the above equipment on the top of the engine as in b), the space for accommodating them will be long. The required length is considerably shorter.

In the case of the small planing boat of claim 2, further, 6) the cylinder of the cylinder is inclined rearward as in the above c) to arrange an intake system device on the engine, and the exhaust system of the exhaust system is arranged rearward of the engine. Since the device is provided, there are the following advantages. That is, since the intake system device in the upper part of the engine is located obliquely above and in front of the cylinder, the above-mentioned condition that the carburetor and the like are arranged close to the upper part of the cylinder is easily satisfied. In addition, the path of the pipe that leads from the intake system to the cylinder and further to the exhaust system becomes a unidirectional path from the front of the hull to the rear, and the flow of gas becomes smooth. In addition, providing the exhaust system equipment to the rear means that the exhaust system equipment does not have the above-mentioned positional restrictions as in the case of the intake system, and the engine exhaust is directed toward the rear of the small planing boat. It is also rational because it is preferable.

According to the small watercraft of claim 3, 7) the crankshaft of the mounted 4-cycle engine can be always connected to the drive shaft of the propulsion means in a preferable state. Even if there is a difference in height (deviation of the shaft center) between the crankshaft and the drive shaft, the bevel gear pair and other gear pairs and the transmission shaft provided as described in d) above will not be able to detect the difference in height. This is because the two will be connected so that they will be resolved. As mentioned above, the drive shaft of the propulsion means is generally provided near the bottom of the hull, whereas the crankshaft of a four-cycle engine with an oil pan is slightly above that of a two-cycle engine. However, in this small planing boat, the rotation of the crankshaft is lower than that of the bevel gear pair or other up to the transmission shaft that is oriented forward and backward (that is, arranged so as to be easily connected to the drive shaft of the propulsion means). It is transmitted by the action of a pair of gears, the transmission shaft of which is connected to the drive shaft of the propulsion means.

8) Further, in the case of the small planing boat of the third aspect, if the tooth ratio of the bevel gear pair and other gear pairs is appropriately set, the rotation speed of the crankshaft at the maximum output of the engine is It is possible to perform so-called matching of the rotational speeds, which is to convert and transmit the rotational speeds to the drive shaft of the propulsion means for the purpose of efficiency.

[0024]

1 to 3 show an embodiment of the present invention. This example relates to a small planing boat 1 equipped with a 4-cycle engine 20. FIG. 1 is a side view of the small planing boat 1 showing a part of it so that the engine 20 and others can be seen, and FIG. Is a cross-sectional view showing in detail, and FIG. 3 is a plan view of the engine 20 and the like (III-I in FIG. 2).
II cross section).

The small planing boat 1 is a water vehicle mainly intended for leisure. As shown in FIG. 1, a hood 3, a seat 4, a handle 5 and the like are mounted on a hull 2 of the bottom of a boat.
Two people are allowed to board. As a propulsion means, a water jet pump 50 is provided in the lower rear part of the hull, and the water jet which is pressurized and jetted by the water jet pump 50 obtains propulsive force to slide on the water surface. The water jet pump 50 is driven by the engine 20, and the engine 20 is a space inside the hull surrounded by the bottom hull 2, the hood 3, the seat 4 and the like in the front and rear center of the hull together with the intake system device 10 and the like. It is installed in the room). The output of the engine 20 is transmitted to a drive shaft 52 through an elastic joint 51, and the drive shaft 52 (the impeller of the pump 50).
To rotate. The engine 20 is mounted on the bottom hull 2 via a damper (not shown) using an elastic body such as a spring or rubber.

As the engine 20, a 4-cycle in-line 4-cylinder engine having the structure shown in FIG. 2A is mounted. A cylinder head 21 is provided above the engine 20, and a cylinder 25 and a crankcase 29 are provided below the cylinder head 21.
An oil pan 34 is provided. The cylinder head 21 has an intake port 22 and an exhaust port 23, and a cam 24b and a timing chain 24c (FIGS. 2B and 3) together with a valve 24a for opening and closing the ports 22 and 23.
A spark plug 21a incorporating a valve mechanism 24 such as
(Fig. 3) is also attached. An intake system device 10 including an intake silencer 11 and a carburetor 12 is connected upstream of the intake port 22, and an exhaust system device 6 such as an exhaust manifold 61 and a muffler 62 is provided downstream of the exhaust port 23.
0 is connected. An outlet portion of the exhaust manifold 61 is inserted into a substantially central portion of the first chamber of the muffler 62, and the exhaust manifold 61 and the muffler 62 are connected by a bellows-shaped rubber tube 63 to form a water jacket 64. Since there is a gap that forms the water jacket 64 between the exhaust manifold 61 and the muffler 62, even if the engine 20 supported by the damper moves, the displacement is absorbed in this gap, and the exhaust manifold 61 is separated from the muffler 62. There is no contact. Since the outlet of the exhaust manifold 61 is located substantially in the center of the muffler 62, the water in the muffler 62 always stays near the inner wall of the muffler 62 even if the small planing boat 1 falls, and the water enters the exhaust manifold 61. There is no fear. The water in the muffler 62 is discharged to the outside of the ship together with the exhaust gas through the outlet pipe. Also,
A piston 26 connected to a crank shaft 28 is arranged inside the cylinder 25 so as to be vertically slidable, and the crank shaft 28 is rotatably supported by a crank case 29. An oil pan 34 for collecting oil is tightly attached to the lower portion of the crankcase 29, and a cylindrical strainer 35 is attached to the lower portion of the depression.
Is arranged and is connected to a fuel pump (not shown). The points described above are not particularly different from the configuration of a general four-cycle engine, but the valve mechanism 24 and the like are provided on the upper portion, the oil pan 34 is provided on the lower portion, and the cylinder is a four-cylinder engine. Therefore, the 4-cycle engine 20 is considerably larger than the normal 2-cycle engine.

The feature of the small planing boat 1 is that the large-sized and heavy 4-cycle engine 20 is mounted in the hull as a propulsion engine as shown in FIG. When the 4-cycle engine 20 is mounted in the hull of the small planing boat 1 having a limited volume, it is necessary to solve the following problems. That is, (a) a four-cycle engine 20 as compared with a two-cycle engine that is generally mounted conventionally.
Is considerably large, it is difficult to properly arrange it in the hull together with the intake system device 10 and the like that should be arranged in a close proximity to the upper part. (B) The weight of the small planing boat 1 is heavy because the 4-cycle engine 20 is heavy. It is necessary to consider the distribution. C) It is preferable to use a wet sump system for the lubrication system, similar to a normal 4-cycle engine, because it is structurally simpler than a dry sump system. 25 (Figs. 2 and 3), which makes it difficult to continue and restart the operation. D) Generally, the crankshaft 28 (Fig. 2) is at a higher position than that of a two-cycle engine, and It is difficult to connect the crankshaft 28 to the drive shaft 52 of the water jet pump 50, which is required to be provided near the bottom. In this respect, the small planing boat 1 solves this problem by adopting the following configuration.

First, to solve the problems a) and b), the 4-cycle engine 20, the intake system device 10 and the exhaust system device 6 are provided.
0 is arranged in the hull as follows. That is, as shown in FIG. 1 and FIG. 2, the engine 20 is placed horizontally (the crankshaft 28 is directed to the left and right of the hull, and the cylinders 25 are arranged along it), and the engine 20 is arranged substantially at the center of the hull width. Inclining to the rear of the hull largely (about 55 °), the intake silencer 11 and the carburetor 12 are placed in the space above the engine 20 (obliquely above the cylinder 25).
The intake system device 10 is arranged. The exhaust system device 60 such as the muffler 62 is placed at a position rearward of the engine 20 with respect to the hull. The rotation of the crankshaft 28 in the horizontally installed engine 20 is transmitted to the front parallel shaft 42 via the spur gear pair 41 as shown in FIG. 2, and the rotation is transmitted to the bevel gear pair 43.
Is transmitted to the shaft 44 facing the front and rear of the hull, and then transmitted to the transmission shaft 46 via the spur gear pair 45. The transmission shaft 46 is
It is arranged so as to extend rearward through a portion above the oil pan 34 under the crankshaft 28, and a joint 51 is provided at the rear end through which a rotational force is pumped by a pump 50 as shown in FIG. To the drive shaft 52 of. One (input side) gear of the gear pair 41 is formed on the outer circumference of the arm of the crankshaft 28 and the balance weight as shown in FIGS. 2 (b) and 3 to suppress an increase in the number of parts. ing.

With the layout as described above, the four-cycle engine 20 and the like can be appropriately arranged in a narrow space inside the hull while solving the problems (1) and (2). The reason is explained as follows based on FIG. Since the engine 20 and the intake system device 10, which has to be arranged close to the cylinder 25, are not adjacent to each other in the width direction of which the dimensions are particularly limited, it is not necessary to increase the width direction dimension of the hull. . Engine 20
Since it is not necessary to place the ship near the left or right of the hull, the center of gravity of the whole can be placed in the center of the width of the hull. Since the space inside the hull is long in the front-rear direction, it is possible to relatively easily arrange the engine 20 or the like in an appropriate position in consideration of the installation space and weight distribution in that direction. Since the cylinder 25 is largely tilted backward, and the intake system device 10 is arranged in the space on the side opposite to that which is obliquely upward, it is easy to provide the carburetor 12 and the like at a close position above the cylinder 25. Similarly, since the cylinder 25 is inclined, the position of the center of gravity of the engine 20 is low, which is preferable in terms of ease of installation of the engine 20 on the hull and stability of running of the hull. Since a wide space is secured in the upper part of the engine 20, the space required before and after the engine 20 can be saved by placing the intake system device 10 there, and moreover, the intake silencer 11 having a large capacity and long in the width direction of the hull is provided. It is possible to use a total of four carburetors 12 connected to each cylinder. Engine 2
Exhaust system device 60 regardless of the relative position with respect to 0
Since the engine 20 and the intake system device 10 are provided at a position at the rear of the hull, which is out of the portions where the engine 20 and the intake system device 10 are vertically arranged, even a hull having a narrow width can be arranged without problems. A passage (exhaust manifold 61, etc.) for intake / exhaust from the intake system device 10 provided obliquely above and in front of the cylinder 25 to the exhaust system device 60 in the rear through the cylinder 25 has little bending and small resistance. It can be defined as a simple route.

In order to solve the problem of (c), as shown in FIGS. 2A and 2B, in the four-cycle engine 20, an oil pan 34 is provided further below the bottom of the crankcase 29. . Normally, the bottom of the crankcase 29 is nothing but the oil pan 34, but in this example,
The bottom of the crankcase 29 and the oil pan 34 are arranged so as to form separate spaces. In other words, under the space of the crankcase 29 that is joined by bolts or the like (not shown) and integrated, the above-mentioned gear pairs 41.4
The oil pan 34 is arranged so as to form a closed space together with the member 47, which also functions as a gearbox for 3/45. The upper and lower spaces formed are connected by two communication holes 31 so that the oil forcibly supplied to the crankshaft 28 and the like is dropped onto the oil pan 34 and collected. Around the communication hole 31, a cylindrical peripheral wall 3 protruding from the crankcase 29 toward the oil pan 34 is formed.
2 is formed so that a large space S is formed around and around the peripheral wall 30 of the communication hole 31 in the closed space above the oil pan 34, as shown in FIG. 2B.

If the oil pan 34 and the like are constructed in this way, the four-cycle engine 20 is of the wet sump type, but the small planing boat 1 falls and the engine 2
There is no fear that the oil in the oil pan 34 will flow into the cylinder 25 even when 0 is overturned or reversed (180 ° inversion). The reason why such inflow does not occur even when the vehicle falls over is that there is a large space S around and around the peripheral wall 30 (communication hole 31) in the space of the oil pan 34. That is, when the engine 20 rolls over or reverses, the oil collects in the space S and hardly reaches the inside of the crankcase 29 from the communication hole 31, and therefore the oil does not reach the inside of the cylinder 25. Of. Although the volume of the left half of the space S in the figure is smaller than that of the right half, even if the oil in the oil pan 34 is large and oil overflows from the communication hole 31 at the time of a fall, the oil will fall below the timing chain tunnel at the time of a fall. It enters into 24d and does not flow into the cylinder 25. Further, in particular, if the small planing boat 1 is equipped with a tipping switch (not shown) that automatically stops the engine 20 when the vehicle topples over, forced refueling of the crankshaft 28 and the like will be stopped when the vehicle is overturned or inverted. So this is even better. Like the cylinder 25 and the cylinder head 21, the oil pan 34 has a water jacket 34a through which cooling water passes, and water taken out from the jet 6 of the water jet shown in FIG. I am trying to cool it. After cooling the oil pan 34 shown in FIG. 2, the cooling water flows into the muffler 62 through the cylinder 25 / cylinder head 21 and the water jacket 64 of the exhaust manifold 61, and is mixed with the high temperature exhaust gas to cool it. It passes through the outlet pipe and is discharged out of the boat from the stern of the small planing boat 1. As a result, the engine 20 can receive proper cooling even though it is arranged in the almost enclosed space of the small planing boat 1.

Since the oil pan 34 is arranged further below the crankcase 29, the height from the bottom (installation surface) of the engine 20 to the crankshaft 28 is particularly large. (See Figure 2)
As described above, by providing the transmission shaft 46 connected to the crankshaft 28 via the gear pairs 41, 43, and 45 in the engine 20, the above problem 2) is solved. That is,
The transmission shaft 46 is provided not only for transmitting the rotation of the crankshaft 28 in the horizontally placed engine 20 rearward at a right angle thereto, but also for extracting the output from the crankshaft 28 below that. As described above, the drive shaft 52 of the water jet pump 50 is connected to the transmission shaft 46 via the elastic joint 51 as shown in FIG. Since the transmission shaft 46 is located close to the bottom of the engine 20, it can be satisfactorily connected to the drive shaft 44 of the water jet pump 45 that needs to be arranged near the bottom of the hull (that is, without almost tilting the drive shaft 44). It has become possible.

Since the gear pairs 41, 43, and 45 are set to an appropriate gear ratio that converts the rotation speed of the crankshaft 28 into a rotation speed that is efficient for the water jet pump 50, the propelling efficiency of the small planing boat 1 is improved. In terms of aspects, it also brought good results. In other words, the output characteristic of the engine 20 and the propulsion efficiency of the water jet pump 50 could be appropriately matched by the total number of teeth ratio of the gear pairs 41, 43, 45. This means that by using an appropriate gear pair, the same type of 4-cycle engine 20 can be mounted on other types of small planing boats equipped with other water jet pumps having different propulsion performances. It will be possible to reduce the cost of small planing boats by promoting the common use of. Needless to say, the same operational effect as above can be obtained when the same gear pair is provided outside the engine 20.

[0034]

In the small planing boat of the present invention, the 4-cycle engine, which is considerably larger than the 2-cycle engine in spite of its merits in terms of cleanliness of exhaust gas, etc. Can be properly arranged as follows.

1) Since the 4-cycle engine is mounted with the crankshaft facing the left and right of the hull, the intake system equipment to be placed in an integral positional relationship with it can be easily arranged in front of or behind the cylinder array surface. it can. That is, since it is not necessary to provide the device or the like on the right or left side of the engine, it is sufficient that the width of the engine room is such that the 4-cycle engine can be placed horizontally, and the hull width is not increased.

2) Since it is not necessary to bring the engine to the left or right of the hull in relation to the intake system equipment, the 4-cycle engine can be mounted at a position preferable in terms of weight balance of the hull.

3) Although the crankshaft is directed to the left and right of the hull, the rotation of the crankshaft is smoothly transmitted to the propulsion means at the rear of the hull by the action of the bevel gear pair. Therefore, it is possible to use the same propulsion means as the conventional one in a preferable mode.

4) Inclining all the cylinders of the engine to suppress the height of the 4-cycle engine, which is supposed to be quite tall, in order to keep the center of gravity of the small planing boat at a low position and improve its stability. You can

5) Since the intake system or the exhaust system equipment is arranged on the upper part of the engine in which the cylinder is inclined and the height is lowered, the required length of the space required as the engine room in the longitudinal direction of the hull is shortened.

The small planing boat of claim 2 has the following advantages. That is, 6) Since the intake system equipment is arranged above the cylinder or the like which is inclined rearward, it is easy to arrange the carburetor or the like close to the upper part of the cylinder. In addition, the piping path from the intake system to the cylinder and further to the exhaust system behind it becomes a simple one-way path from the front of the hull to the rear, and the flow of gas through it is smooth. become.

According to the small planing boat of claim 3, in addition to the above, 7) a gear pair including a bevel gear pair and a transmission shaft are not generated between the crankshaft of the 4-cycle engine and the drive shaft of the propulsion means. The inconvenience due to the height difference is eliminated, and at the same time, the rotational speeds of the engine and the propulsion means are matched, so that the crankshaft and the drive shaft can be always connected in a preferable state.

[Brief description of drawings]

FIG. 1 is a side view of a small planing boat 1 according to an embodiment of the present invention, with a part thereof seen through so that a 4-cycle engine 20 and the like can be seen.

2 (a) is a side view showing in detail a cross-sectional view of only a 4-cycle engine 20 of the small planing boat 1 shown in FIG. 1, and FIG. 2 (b) is a side view of the engine 20. 3B is a sectional view taken along line bb in FIG. 3A, and FIG.
It is a cc sectional view in (a).

3 is a plan view of the 4-cycle engine 20 and the like, which is a sectional view taken along line III-III in FIG. It should be noted that the transmission shaft 46 and the like, which are directly below the shaft 44, are actually drawn laterally in the figure for the sake of convenience.

[Explanation of symbols]

 1 Small Planing Boat 10 Intake System Equipment 20 4 Cycle Engine 25 Cylinder 28 Crank Shaft 41/45 Gear Pair 43 Bevel Gear Pair 46 Transmission Shaft 50 Water Jet Pump (Propulsion Means) 60 Exhaust System Equipment

Claims (3)

[Claims] 1. A small planing boat in which the driving engine of the propulsion means is mounted in a space surrounded by a hull outer plate, and the four-cycle engine has the crankshaft as a left and right side of the hull. And its crankshaft is connected to a rear propulsion means via a bevel gear pair, and all cylinders of the 4-cycle engine incline to either the front or rear of the hull, including the inclined cylinders. A small planing boat characterized by having an intake system or exhaust system equipment placed above the engine. 2. All cylinders of a 4-cycle engine are inclined rearward of the hull so that intake system equipment is arranged above them and exhaust system equipment is arranged rearward of the 4-cycle engine. The small planing boat according to claim 1. 3. The crankshaft is connected to the propulsion means via the bevel gear pair, another gear pair, and a transmission shaft arranged rearward and below the crankshaft.
Or the small planing boat described in 2.