JPH0429595B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine cooling system for a waterjet propulsion type small watercraft having a deck on which about one or two people can board.

(Prior Art) FIG. 4 shows an example of this type of small watercraft. In this figure, reference numeral 1 denotes a hull, and the hull 1 has a deck 2 at the stern part with enough space for one person to board in a standing position. In this small watercraft, cooling water for the engine (not shown) is taken in from the outside and discharged outside the hull 1 after use. Such prior art is disclosed in Japanese Utility Model Publication No. 53-33352.

FIG. 5 shows the internal structure of the small watercraft. In this figure, 3 is an engine, 3A is an engine body consisting of a cylinder head 3a and a cylinder block 3b (not shown), 4 is an output shaft of the engine 3,
5 is a propulsion device. The propulsion device 5 includes a drive shaft 6 connected to the output shaft 4, an impeller 7, a jet duct 8,
It consists of a stationary blade 9, a steering nozzle 10, etc.

The jet duct 8 houses the impeller 7, fixes the stationary blades 9 behind the impeller 7, and has a duct constriction part 8a further behind it. The propulsion device 5 transmits the output obtained by the engine 3 to an impeller 7.
With the rotation of , water is ejected to the rear of the jet duct 8,
Provides propulsion to small boats. In other words, this small watercraft is waterjet propulsion type. The steering nozzle 10 rotates in a horizontal plane in accordance with the rotation of the handle 11 shown in FIG. 4, and determines the direction of propulsion of the small watercraft.

The cooling water system path in this small boat is as follows.

12 in Fig. 5 is the cooling water intake port for the engine 3;
It is provided in a portion of the jet duct 8 that houses the impeller 7, behind the impeller 7 and in front of the duct constriction portion 8a. This cooling water intake port 12 is connected from a supply passage 13 to a water jacket (not shown) of the engine main body 3A, a water jacket connecting passage 14, a water jacket (not shown) of the exhaust manifold 15 of the engine 3, and a water jacket outlet pipe 16.
Connect to.

The exhaust manifold 15 includes a muffler 17, an exhaust silencer 18, an exhaust chamber 19, and an exhaust port 20.
communicate with.

Next, the operation of the small watercraft having the above configuration will be explained.

FIG. 6 shows a conventional engine 3. engine 3
When the cylinder block 3b is activated, the exhaust gas flows through the cylinder block 3b.
from the exhaust port 3c to the exhaust manifold 15 and the exhaust pipe 2
1 in the direction of arrow A, and muffler 17 in Fig. 5.
is exhausted. On the other hand, due to the operation of engine 3,
When the impeller 7 rotates, the static pressure near the cooling water intake 12 increases, and the cooling water flows from the cooling water intake 12 in the direction of arrow B through the supply passage 13 to the intake plug 22 of the water jacket in FIG. The water is then guided into the water jacket of the engine 3. After this cooling water flows through the water jackets (not shown) of the cylinder block 3b and cylinder head 3a, it flows from the elbow 14a of the water jacket connecting passage 14 and the pipe 14b to the water jacket (not shown) of the exhaust manifold 15. ) to cool them down. The cooling water then flows through the water jacket outlet pipe 16 and joins the exhaust gas in the exhaust pipe 21. 21A is this confluence port.

FIG. 7 schematically shows FIG. 6, and in this figure, the shaded area is the water jacket 2 of the engine 3.
3, 23A is a water jacket of the engine main body 3A, and 23B is a water jacket of the exhaust manifold 15.

The cooling water flowing from the water jacket 23 to the confluence port 21A of the exhaust pipe 21 flows into the muffler 1 shown in FIG.
7. From the exhaust silencer 18 and the exhaust chamber 19, through the exhaust port 20, the pressure of the exhaust gas flows out of the hull 1 in the form of a jet or mist to the bow section 1.
released from a. At this time, the cooling water cools the exhaust gas, the exhaust pipe 21, and the like.

(Problem to be Solved by the Invention) However, this type of small boat may sometimes turn upside down. At that time, the engine 3 may stop. FIG. 8 schematically shows FIG. 6 when the small boat is reversed. In this figure, the confluence port 21A is located at the top surface of the water jacket 23.
Since its height is lower than W ₁ , the water in the water jacket 23 overflows from the confluence port 21A,
It accumulates in the upper part 15a of the exhaust manifold 15. Then, when the small watercraft is turned over and returned to the original state shown in FIG. ).
In this way, if the cooling water flows into the combustion chamber of the engine, the engine 3 will not be able to operate normally, and
The durability of the engine 3 decreases.

This invention was made to solve the above-mentioned conventional problems, and allows the engine to operate normally.
Another object of the present invention is to provide an engine cooling system for a waterjet propulsion type small watercraft, which has an excellent engine durability.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a system in which a confluence port where cooling water joins exhaust gas is approximately at the same height as the top surface of a water jacket when a small watercraft is turned over. , or higher.

(Function) According to the present invention, since the confluence port is located at approximately the same height as or higher than the top surface of the water jacket during inversion, cooling water does not overflow into the exhaust manifold during inversion. There is no. Therefore, when the small watercraft is returned to its original state after being reversed, water will not flow into the combustion chamber of the engine.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the invention, FIG. 2 schematically shows FIG. 1, and FIG. 3 schematically shows FIG. 1 in a state where the small watercraft is inverted. In these figures, the same or corresponding parts as the example of the small watercraft and the conventional example of FIGS. 4 to 8 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, the confluence port 21A of the water jacket outlet pipe 16 is provided at the lower part of the exhaust pipe 21, and as shown in _FIG . Height is set. In this way, when the small watercraft is turned over, the merging port 21A becomes approximately at the same height as the uppermost surface _W1 of the water jacket 23, as shown in FIG.

In this way, since the confluence port 21A is located at approximately the same height as the uppermost surface _W1 of the water jacket 23 during the reversal, the cooling water does not overflow into the exhaust manifold 15 during the reversal. Therefore, when the small boat is returned to the state shown in FIG. 2 after being reversed, water will not flow into the combustion chamber (not shown) of the engine.

In addition, in this embodiment, the confluence port 21A in FIG.
is located at approximately the same height as the top surface _W1 of the water jacket 23, so the exhaust pipe 21 is located at the same height as the top surface W1 of the water jacket 23.
Cooling water and cooling water sent out from the confluence port 21A can provide cooling without any corners. Therefore, during normal operation of the engine 3, the exhaust pipe 21 can be sufficiently cooled.

In this embodiment, in order to make the explanation easier to understand, the heights of the lowermost surface _W2 of the water jacket 23 and the confluence port 21A in FIG. 2 are made substantially the same, but the height is not limited to this. A small boat may turn over in a tilted state, but in this case, in consideration of this tilt, the lowermost surface in Figure 2 should be adjusted in advance so that the confluence port 21A in Figure 3 is approximately the same height as _W1 . It is sufficient to set the height relationship between W ₂ and the confluence port 21A.

Of course, the height of the confluence port 21A can also be made higher than _W1 .

(Effects of the Invention) As explained above, according to the present invention, in the exhaust manifold of a small boat that may be inverted,
By preventing the intrusion of cooling water, the small watercraft can be operated normally and the durability of the engine can be improved. Furthermore, the structure and parts are extremely simple and unchanged from the conventional ones.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of an engine according to the present invention, Fig. 2 is a schematic diagram of the engine, Fig. 3 is a schematic diagram of the engine when reversed, Fig. 4 is a perspective view of an example of a small boat, and Fig. 5 6 is an exploded perspective view of a conventional engine, FIG. 7 is a schematic diagram of the engine, and FIG. 8 is a schematic diagram of the engine when reversed. 1... Hull, 3... Engine, 5... Propulsion device, 21
...Exhaust pipe, 21A...Confluence port, 23, 23A, 23
B...Water jacket, W ₁ ...Top surface.

Claims (1)

[Claims] 1 Engine cooling of a waterjet propulsion type small watercraft equipped with a cooling water system path in which the cooling water taken in from the waterjet propulsion device flows through the engine's water jacket, joins the exhaust gas in the engine's exhaust pipe, and is discharged outside the hull. In the device, the confluence port through which the cooling water joins the exhaust gas is set at approximately the same height as the top surface of the water jacket when the small watercraft is turned over, or at a height higher than that. Engine cooling system for small water jet propulsion boats.