JPS63212199A - Exhaust structure of ship propeller - Google Patents

Abstract

PURPOSE:To prevent intrusion of cooling water into a combustion chamber by having a cooling water jacket provided around an exhaust expansion chamber communicated to the position on the exhaust lower stream side from an exhaust introduction part in an exhaust passage. CONSTITUTION:Cooling water having passed a water jacket 33 of an engine 12 passes in water jackets 50-53 and cools an exhaust box 35. At this time, the water jackets 50-53 are communicated to each other, and the cooling water is discharged from an exhaust introduction part 54 of an exhaust passage 46A through a communication part 55 in the middle of the exhaust lower stream side to an exhaust passage 46B without passing through an exhaust expansion chamber 45. As the exhaust introduction part 54 is located upper than the communication part 55 in this way, drain can be prevented from being dragged or flown into the exhaust expansion chamber 45 or the engine 12 because of exhaust pressure wave, posture change of a boat body and so forth.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust structure for a marine vessel propulsion engine such as an inboard motor or an outboard motor.

[Prior art] Water jet propulsion devices, etc. that have an engine inside the hull,
An exhaust expansion chamber that communicates with the exhaust outlet portion of the engine body and is attached to the engine body, an exhaust passage that communicates with the exhaust expansion chamber and discharges exhaust gas toward the outside of the boat, and is provided around the exhaust expansion chamber.

An exhaust structure is employed that includes a wooden jacket that communicates with the exhaust passage and drains cooling water into the exhaust passage.

According to this exhaust structure, the exhaust gas passing through the exhaust expansion chamber is water-cooled, thereby reducing the back pressure against the combustion chamber due to the cooling effect of the exhaust gas and increasing the efficiency of sucking the exhaust gas into the combustion chamber.
In addition, it suppresses overheating of the exhaust box that forms the exhaust expansion chamber, and prevents material deterioration and painted surface deterioration due to the high temperature of the exhaust box.
Deterioration of the rubber exhaust pipe connected to the exhaust box can be prevented.

Further, the exhaust gas expansion chamber can also provide an exhaust noise silencing effect.

Here, in the exhaust structure L, the water jacket is opened toward the exhaust expansion chamber, and the exhaust pipe introduction part of the exhaust passage is connected to the lowest level surface inside the exhaust expansion chamber. The cooling water discharged from the water jacket is
Without providing a special drainage passage, the air is allowed to flow down the bleed passage while being cooled with water, and is then discharged overboard.

[Problems to be Solved by the Invention] However, in the conventional exhaust structure described above, the cooling water discharged from the water jacket accumulates on the lowest level surface of the exhaust expansion chamber, and the accumulated water causes exhaust pressure waves. Otherwise, there is a risk that it may enter the combustion chamber of the engine body due to changes in the attitude of the ship.

This intruding water causes rust on the inside of the combustion chamber, the piston, etc., and causes malfunction of the engine.

The present invention provides an IE system in which an exhaust box forming an exhaust expansion chamber is water-cooled, and the cooling water subjected to the water cooling is drained through an exhaust passage.
The purpose of the present invention is to prevent the cooling water from entering the combustion chamber.

Furthermore, it is an object of the present invention to enable the exhaust box to be installed in the engine body in a compact manner.

[Means for Solving the Problems] The present invention provides an exhaust expansion chamber that communicates with the exhaust outlet of the engine body and is attached to the engine body, and an exhaust gas expansion chamber that communicates with the exhaust expansion chamber and discharges exhaust gas toward the outside of the boat. In an exhaust structure for a marine propulsion device, the exhaust structure includes a passage and a water jacket provided around an exhaust expansion chamber and communicating with the exhaust passage to drain cooling water into the exhaust passage. The exhaust introduction part communicates with the downstream part of the exhaust gas, and the exhaust introduction part of the exhaust passage is arranged above the communication part of the wood jacket.

[Function] According to the present invention, the cooling water that cooled the exhaust box is discharged to an intermediate portion of the exhaust passage downstream of the exhaust gas introduction part without passing through the exhaust expansion chamber, and is ultimately discharged overboard. Ru. Here, since the exhaust introduction part of the exhaust passage connected to the exhaust expansion chamber is set above the part connected to the water jacket, the cooling water discharged into the exhaust passage causes exhaust pressure waves.

Or, due to changes in the attitude of the ship, the exhaust gas will not be drawn into or flow into the exhaust expansion chamber, or even into the combustion chamber of the engine body.

That is, the exhaust box forming the exhaust expansion chamber is water-cooled, and the cooling water used for the water cooling is drained through the exhaust passage fE.
', it is possible to prevent the cooling water from entering into the combustion chamber.

Furthermore, by extending the exhaust passage communicating with the exhaust expansion chamber downward from the bottom side of the exhaust box that forms the exhaust expansion chamber, the front part of the exhaust box can be effectively used as a space for installing other parts such as an electrical equipment box. .

Incidentally, small water jet propulsion boats and the like that are long in the longitudinal direction and have watertight hulls may overturn or rotate during navigation. At this time.

In the present invention, there is a risk that cooling water may enter the lower part of the exhaust expansion chamber from the exhaust introduction part of the exhaust passage and accumulate there. This may cause corrosion of the infiltrated water retention section, or if the number of overturns becomes excessive, there is a possibility that the infiltrated water may infiltrate into the engine side from the exhaust expansion chamber.

Therefore, in implementing the present invention, if the lower part of the exhaust expansion chamber and the water jacket are communicated with each other through a small hole, water accumulated in the lower part of the exhaust expansion chamber, pressure of exhaust gas in the exhaust expansion chamber, or water The water flowing through the jacket flows out of the exhaust expansion chamber either through the suction action at the communicating small holes.

At this time, if the opening of the small hole on the water jacket side is directed toward the downstream side of the water jacket, the suction action of water in the communicating small hole can be utilized more effectively. Furthermore, if a check valve is provided at the opening of the small hole on the water jacket side, it is possible to reliably prevent water flowing through the water jacket from flowing back into the exhaust expansion chamber.

Furthermore, in the practice of the present invention, even when the lower part of the exhaust expansion chamber and the exhaust passage are communicated with each other through a small hole, the accumulated water in the lower part of the exhaust expansion chamber is caused by the pressure of the exhaust gas in the exhaust expansion chamber or the exhaust passage. The exhaust gas flowing through the exhaust gas can be caused to flow out of the exhaust expansion chamber by either the suction action at the communicating small holes.

[Example] Fig. 1 is a sectional view showing a water jet propulsion ship equipped with a water jet propulsion device to which the present invention is applied, Fig. 2 is a plan view of the main part of Fig. 1, and Fig. 3 is a plan view of the main part of Fig. 1. An arrow view along the mm line of
Fig. 4 is a partially cutaway view taken along line 17-rV in Fig. 3, Fig. 5 is a sectional view showing a part of the exhaust box taken out, and Fig. 6 is an end view of Fig. 5. .

As shown in FIGS. 1 and 2, the water jet propulsion boat 10 has a two-cylinder engine 12 disposed inside the hull 11, and a water injection unit 13 disposed outside the hull 11 at the rear lower part. , the engine 12 and the impeller 14 of the water jet 1) t unit) 13 are connected by a transmission shaft 15. That is, the engine 12 and the water injection unit 13 form a water jet propulsion device which is a marine vessel propulsion device. 16 is the seat, 1
7 is a handle device.

As shown in FIG. 3, the engine 12 is installed on a bed 19 of the hull 11 via a vibration-proof rubber 18. The engine 12 includes a coolant case 2o, a cylinder block 2
1. The cylinder head 22 constitutes the engine body, and a flywheel magneto device 2 is attached to one end of the crankshaft 23.
124, and the engine side end of the transmission shaft 15 is coupled to the other end via a joint 25. An intake system piping including a carburetor 26 is connected to the engine 12, and an exhaust system piping described below is also connected thereto.

The water injection unit 13 is installed in a recess 11A provided on the rear outer surface of the hull 11, and is fixed to the transmission shaft 15 to generate thrust. The steering nozzle 28 follows the steering nozzle 28. A fixed blade 29 is provided inside the casing 27 on the downstream side of the impeller 14 . 30 is a bottom plate, and 31 is a screen plate.

The water injection unit/G 13 is a fixed wing 29 of the casing 27.
One end of the cooling water introduction pipe 32 is opened in the part facing the (
(Fig. 2), the cooling water introduction pipe 32 takes in a part of the jet generated by the water injection unit (13) as cooling water, and makes it possible to guide this cooling water to the water jacket 33 of the engine 12 (Fig. 4). ).

The exhaust structure of the engine 12 will be described below.

The engine 12 has an exhaust cover 3 as shown in FIG.
4. An exhaust box 35 is connected. The exhaust cover 34 includes a first cover part 36 and a second cover part 37 that are integrated with each other.
and a third cover portion 38. Further, the exhaust box 35 includes a main body portion 39 and a cylindrical exhaust pipe portion 40, which are integrally formed with each other. It also includes an inner box part 41 and an outer box part 42 which are integrated into the main body part 39. The main body part 39, the inner box part 41, and the outer box part 42 are fixed to the engine 12 in an integrally connected state. The exhaust box 35 has a long shape in the longitudinal direction of the crankshaft, and is arranged above the engine 12. Note that the exhaust box 35 is provided with a reinforcing rib 39A between the main body portion 39 and the exhaust pipe portion 40.

That is, as shown in FIGS. 1 to 4, the engine 12
The exhaust outlet section 43 (FIG. 3) that opens into the combustion chamber of the exhaust box 35 is connected to the exhaust outlet section 43 (Fig.
The exhaust expansion chamber 4 formed by the main body part 39 and the inner box part 41
5. Exhaust passages 46A and 46B formed by the inner box part 41 and outer box part 42 of the exhaust box 35, a rubber exhaust hose 47, and an exhaust expansion chamber 48. Each of the rubber exhaust hoses 49 is connected. The exhaust expansion chamber 48 is long in the front-rear direction so that a sufficient volume can be secured, and it is formed small in the lateral direction, contributing to making the overall size of the engine compact. The exhaust hose 49 connects to the exhaust expansion chamber 4
Extending straight downward from 8, then facing rearward, hull 1
It penetrates the rear inner wall below the exhaust box 35 of No. 1 and opens into the four parts 11A. Note that the exhaust communication path 44B formed by the exhaust pipe section 40 projects a certain length into the exhaust expansion chamber 45 and opens. According to this exhaust structure, - by appropriately setting the lengths of the exhaust communication paths 44A and 44B, an exhaust pressure wave is applied to the combustion chamber of the engine 12 at an appropriate timing to improve the intake air filling efficiency; Further, the exhaust gas expansion chambers 45, 48 can provide an exhaust noise silencing effect.

Further, each cover part 36 to 38 of the exhaust cover 34 forms a water jacket 50, the main body part 39 of the exhaust box 35 forms a water jacket 51, and the exhaust pipe part 40 of the exhaust box 35 forms a water jacket 50, The inner box v&41 and the outer box part 42 of the exhaust box 35 form a water jacket 53. The water jackets) 50 to 53 communicate with each other, and the cooling water that has passed through the water jacket 33 of the engine 12 flows through the water jackets) 50 to 53.
52 and drains from the wooden jacket 53.

The water jacket 53 communicates with the exhaust downstream side of the exhaust introduction part 54 of the exhaust passage 46A opening into the exhaust expansion chamber 45, that is, with the intermediate part of the exhaust passages 46A and 46B, and allows the cooling water to flow from the communication part 55. It can be released into the exhaust gas. That is, the exhaust introduction portion 54 of the exhaust passage 46A is arranged vertically above the communication portion 55 of the water jacket 53.

An exhaust passage 46B communicating with the exhaust Al expansion chamber 45 extends downward from the lower surface of the outer box portion 42 of the exhaust box 35, and an exhaust hose 47 is connected to this extended portion. As a result, a space is secured in the interior of the hull 11 in front of the exhaust box 35 to install the electrical equipment box 56 in which one ignition coil is built. 57 is a spark plug.

The hull 11 is provided with an engine room cover 58 removably above the engine 12. - Next, the operation of the above embodiment will be explained.

According to the above embodiment, the cooling water that cooled the exhaust box 35 is
Without passing through the exhaust expansion chamber 45, the water is discharged to an intermediate portion of the exhaust passage 46A on the downstream side of the exhaust gas introduction section 54, and is eventually discharged overboard. Here, exhaust passage 4
Since the exhaust groove and inlet 54 connected to the exhaust expansion chamber 45 of 6A are set above the part connected to the water jacket 53, the cooling water discharged into the exhaust passage 1146B causes an exhaust pressure wave or a change in the attitude of the hull 11. As a result, the exhaust gas will not be drawn into or flow into the exhaust expansion chamber 45 and, by extension, into the combustion chamber of the engine 12.

That is, under the condition that the exhaust box 35 forming the exhaust expansion chamber 45 is water-cooled and the cooling water subjected to the water cooling is drained through the exhaust pipe below the exhaust passage 468, the intrusion of the cooling water into the combustion chamber is prevented. It can be prevented.

Note that by extending the exhaust passage 46B communicating with the exhaust expansion chamber 45 downward from the lower surface side of the exhaust box 35 forming the exhaust expansion chamber 45, the front part of the exhaust box 35 is connected to the electrical equipment box 5.
6 can be effectively used as installation space. The exhaust passage does not protrude to the side of the engine body, but extends straight downward from the exhaust box, so the width of the engine body becomes smaller. This means that the cross-sectional area of the water jacket propulsion vessel can be reduced, and the hull resistance can be reduced. Further, since the exhaust expansion chamber is given a sufficient volume, it is effective in reducing noise.

Incidentally, the water jet propulsion vessel 10 having a longitudinally long hull and a watertight structure may overturn or rotate during navigation. At this time, in the above embodiment,
There is a risk that cooling water may enter the lower part of the exhaust expansion chamber 45 from the exhaust introduction part 54 of the exhaust passage 46A and accumulate there.

This gives rise to the possibility that the infiltrated water may infiltrate into the engine side through the exhaust pipe 44B if the infiltrated water scavenging section is corroded or the number of falls becomes excessive.

Therefore, in carrying out the present invention, if the lower part of the exhaust expansion chamber 45 and the water jacket 53 are communicated with each other through small holes 101 and 102 as shown in FIGS. The accumulated water in the lower part of the i! It will flow out of the exhaust expansion chamber 45 by either the suction action at the small holes 101 or 102. At this time, as shown in FIG. 9, if the water jacket side opening of the small hole 102 is directed toward the downstream side of the water jacket 53, the suction action of water in the communicating small hole 102 can be used more effectively. . In addition, as shown in Fig. 7, small hole 1
If the check valve 103 is disposed at the water jacket side opening of 01, the possibility that water flowing through the water jacket 53 will flow back into the exhaust expansion chamber 45 can be reliably prevented.

Further, in carrying out the present invention, even when the lower part of the exhaust expansion chamber 45 and the exhaust passage 46A are communicated through the small hole 104 as shown in FIG. 8, the accumulated water in the lower part of the exhaust expansion chamber is
i! of the pressure of the exhaust gas inside the exhaust expansion chamber 45 or the exhaust gas flowing through the exhaust passage 46A. It can be made to flow out of the exhaust expansion chamber 45 by either the suction action at the small fi hole 104.

[Effects of the Invention] As described above, according to the present invention, the cooling water that cooled the exhaust box is drained to an intermediate portion of the exhaust passage downstream of the exhaust gas introduction part without passing through the exhaust expansion chamber. , and eventually ejected overboard.

Here, the exhaust introduction part connected to the exhaust expansion chamber of the exhaust passage is
Since it is set above the part connected to the water jacket, the cooling water discharged into the exhaust passage can be drawn into the exhaust expansion chamber and eventually into the combustion chamber of the engine body due to exhaust pressure waves or changes in the attitude of the hull. There is no flow.

That is, when the exhaust box forming the exhaust expansion chamber is water-cooled and the cooling water subjected to water cooling is drained through the exhaust passage, it is possible to prevent the cooling water from entering the combustion chamber. .

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a water jet propulsion ship equipped with a water jet propulsion device to which the present invention is applied, Fig. 2 is a plan view of the main part of Fig. 1, and Fig. 3 is a - arrow view along the line,
Fig. 4 is a partially cutaway view taken along line IT-1'V in Fig. 3, Fig. 5 is a sectional view showing a part of the exhaust box taken out, and Fig. 6
The figure is an end view of FIG. 5, and FIG. 7 is a sectional view of a main part showing a modification of the present invention. FIG. 8 is a sectional view of a main part showing another modification of the present invention, and FIG. 9 is a sectional view of a main part showing another modification of the invention. DESCRIPTION OF SYMBOLS 10... Water jet propulsion vessel, 12... Engine, 35... Exhaust box, 43... Exhaust outlet part, 45... Exhaust expansion chamber, 46A, 46B...
・Second exhaust passage, 51-53...Water jacket, 54...Exhaust introduction part, 55...Communication part, 56...Electrical box, 101.1
02.104...Small hole, 103...Check valve. Agent Patent Attorney Osamu Shiokawa Figure 2 Figure 3rXJ -■ Figure 5 Figure 6! J7WJ No. 8

Claims (6)

[Claims] (1) An exhaust expansion chamber that communicates with the exhaust outlet of the engine body and is attached to the engine body, an exhaust passage that communicates with the exhaust expansion chamber and discharges exhaust outwards, and an exhaust passage provided around the exhaust expansion chamber. In an exhaust structure for a marine propulsion device, the water jacket also has a water jacket communicating with the exhaust passage and discharging cooling water into the exhaust passage, wherein the water jacket is communicated with a downstream part of the exhaust from the exhaust introduction part in the exhaust passage. Also, an exhaust structure for a marine propulsion device, characterized in that an exhaust introduction part of the exhaust passage is arranged above a communication part of the water jacket. (2) An exhaust box is arranged approximately above an engine body having multiple cylinders, an exhaust outlet is arranged on one end face of the engine body in the longitudinal direction of the crankshaft, and the exhaust outlet and the exhaust box are arranged on the one side. The exhaust introduction part of the exhaust passage communicating with the exhaust expansion chamber is arranged at the upper part of the end face of the engine body on the other side of the exhaust box, and the exhaust passage is arranged downward from the bottom side of the exhaust box forming the exhaust expansion chamber. An exhaust structure for a marine propulsion device according to claim 1, which is extended to. (3) The exhaust structure for a marine propulsion device according to claim 1, wherein the lower part of the exhaust expansion chamber and the water jacket are communicated through a small hole. (4) The exhaust structure for a marine vessel propulsion device according to claim 3, wherein the water jacket side opening of the small hole is directed toward the downstream side of the water jacket. (5) The exhaust structure for a marine vessel propulsion device according to claim 3, wherein a check valve is disposed at the water jacket side opening of the small hole. (6) The exhaust structure for a marine propulsion device according to claim 1, wherein the lower part of the exhaust expansion chamber and the exhaust passage are communicated with each other through a small hole.