JPH0698956B2 - Exhaust structure of ship propulsion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust structure of a ship propulsion device such as an inboard motor and an inboard / outboard motor.

[Prior Art] A water jet propulsion device or the like having an engine in a hull,
An exhaust expansion chamber that is connected to 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 the exhaust gas toward the outboard, and is provided around the exhaust expansion chamber. An exhaust structure having a water jacket communicating with the passage and draining cooling water to the exhaust passage is adopted.

According to this exhaust structure, the exhaust gas that passes through the exhaust expansion chamber is water-cooled, whereby the back pressure on the combustion chamber is reduced by the cooling effect of the exhaust gas, and the efficiency of sucking the exhaust gas into the thermal firing chamber is increased,
Moreover, by suppressing overheating of the exhaust box forming the exhaust expansion chamber, the deterioration of the material due to the high temperature of the exhaust box, the deterioration of the surface coated surface,
It is possible to prevent deterioration of the rubber exhaust pipe connected to the exhaust box. Further, it is possible to obtain the effect of silencing the exhaust gas by the exhaust expansion chamber.

Here, in the above-mentioned exhaust structure, the water jacket is opened toward the exhaust expansion chamber, and the exhaust pipe introduction portion of the exhaust passage is opened to the lowest level surface portion inside the exhaust expansion chamber,
As a result, the cooling water discharged from the water jacket is allowed to flow down while cooling the water in the exhaust passage without further providing a special drain passage, and then discharged to the outside of the ship.

[Problems to be Solved by the Invention] However, in the above-described conventional exhaust structure, the cooling water discharged from the water jacket accumulates at the lowest level surface portion of the exhaust expansion chamber, and the accumulated water causes the exhaust pressure wave, Or, there is a possibility that it may enter the combustion chamber of the engine body due to changes in the attitude of the hull. The infiltrated water causes rust on the inner surface of the combustion chamber, the piston, etc., and causes malfunction of the engine.

In Japanese Utility Model Laid-Open No. 58-22411, as a cooling type exhaust pipe device for a marine internal combustion engine, an exhaust gas introducing portion of an exhaust passage is arranged above a communicating portion of a water jacket with respect to the exhaust passage, and cooling water is supplied to the engine. It is disclosed to try to prevent entry into the combustion chamber of the body. However, in this prior art, (a) "the exhaust pipe 8 opening to the exhaust gas chamber 9 penetrates the outer wall of the cooling water chamber 6" and the sealing is required, and the exhaust structure becomes complicated, (B) "The exhaust pipe 8 is separated from the inner wall of the exhaust gas chamber 9 and the exhaust gas introduced into the exhaust gas chamber 9 is difficult to smoothly flow into the exhaust pipe 8". It is difficult to secure.

An object of the present invention is to prevent the cooling water from entering the combustion chamber of the engine body when the water jacket is provided around the exhaust expansion chamber, while simplifying the exhaust structure and ensuring a smooth flow of the exhaust gas. And

[Means for Solving the Problems] The present invention is directed to an exhaust expansion chamber that communicates with an exhaust outlet portion of an engine body via a first exhaust passage, and an exhaust expansion chamber that communicates with the exhaust expansion chamber and discharges exhaust gas toward the outboard. An exhaust structure for a marine propulsion device, comprising a second exhaust passage and a water jacket provided around the exhaust expansion chamber, the water jacket communicating with the second exhaust passage and discharging cooling water to the second exhaust passage, The exhaust expansion chamber is composed of an inner cylinder and an outer cylinder, and the first exhaust passage is connected to one end of the exhaust expansion chamber and opens toward the inner surface of the other end of the inner cylinder to form the inner cylinder. A water jacket is formed by guiding cooling water into the space between the outer cylinders, and the second exhaust passage is connected to the bottom wall of the outer cylinder at the other end of the exhaust expansion chamber and an opening is formed in the bottom wall of the inner cylinder. And a third exhaust passage that extends vertically inside the inner cylinder is provided. The wall surface of the exhaust passage is brought into contact with the inner surface of the other end of the inner cylinder, the lower end opening of the third exhaust passage is communicated with the opening opening in the bottom wall of the inner cylinder, and the upper end opening is opened inside the inner cylinder. It is the one.

[Operation] According to the present invention, there are the following operation effects.

The cooling water obtained by water-cooling the inner cylinder into which the exhaust gas is introduced is drained to the second exhaust passage without passing through the inner cylinder, and is then discharged to the outside of the ship.

Here, a third exhaust passage extending vertically is provided inside the inner cylinder, and a lower end opening of the third exhaust passage is communicated with an opening opening in a bottom wall of the inner cylinder, and an upper end opening is inside the inner cylinder. Since it is opened, even if the cooling water discharged into the second exhaust passage tries to flow into the inner cylinder due to the exhaust pressure wave, the attitude change of the hull, etc., this is blocked in the third exhaust passage, and the cooling water is cooled by the engine body. Will not be drawn into or flow into the combustion chamber of.

By connecting the second exhaust passage to the bottom wall of the outer cylinder and forming the opening in the bottom wall of the inner cylinder at the other end of the exhaust expansion chamber, a portion for discharging the cooling water into the exhaust is configured. There is. That is, the structure is simplified because it is only necessary to provide openings in the bottom walls of the outer cylinder and the inner cylinder without taking a special drainage structure.

The first exhaust passage is opened toward the inner surface of the other end of the inner cylinder, and the wall surface of the third exhaust passage provided so as to extend vertically inside the inner cylinder contacts the inner surface of the other end of the inner cylinder. Since they are in contact with each other, the exhaust gas introduced into the inner cylinder by the first exhaust passage hits the inner surface of the other end of the inner cylinder, and then is guided by the inner surface of the other end of the inner cylinder and flows into the third exhaust passage.

Therefore, even if the vertically extending third exhaust passage is provided inside the inner cylinder, the exhaust gas can smoothly flow into the third exhaust passage.

[Embodiment] FIG. 1 is a sectional view showing a water jet propulsion ship equipped with a water jet propulsion apparatus to which the present invention is applied, FIG. 2 is a plan view of a main part of FIG. 1, and FIG. 3 is FIG. III-III line view of FIG. 4, FIG. 4 is a partially broken arrow view along line IV-IV of FIG. 3, FIG. 5 is a cross-sectional view showing a part of the exhaust box, 6
The figure is an end view of FIG.

The water jet propulsion ship 10 is, as shown in FIGS. 1 and 2,
An engine 12 having two cylinders is arranged inside the hull 11, a water injection unit 13 is arranged outside the hull 11 at a lower rear portion, and the engine 12 and an impeller 14 of the water injection unit 13 are connected to a transmission shaft 15
Are linked by. That is, the engine 12 and the water injection unit 13 form a water jet propulsion device which is a ship propulsion device. 16 is a seat and 17 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. Engine 12
The crankcase 20, the cylinder block 21, and the cylinder head 22 constitute an engine body, the crankshaft 23 is provided with a flywheel magneto device 24 at one end, and the joint is provided at the other end.
The end of the transmission shaft 15 on the engine side is connected via 25.
The engine 12 is connected with an intake system pipe including a carburetor 26 and an exhaust system pipe described later.

The water injection unit 13 is mounted on a recess 11A provided on the outer surface of the ship bottom rear side of the hull 11, and is fixed to the transmission shaft 15 to generate the thrust, the impeller 14, the casing 27 provided around the impeller 14, the casing 27 Steering nozzle 28 following
It consists of Impeller inside casing 27
Fixed vanes 29 are provided on the downstream side of 14. 30 is a bottom plate and 31 is a screen plate.

The water injection unit 13 has one end of a cooling water introduction pipe 32 opened in a portion of the casing 27 facing the fixed blade 29 (FIG. 2). The cooling water introduction pipe 32 takes in a part of the jet flow generated by the water injection unit 13 as cooling water, and can guide the 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 34, as shown in FIG.
The exhaust box 35 is connected. The exhaust cover 34 includes a first cover portion 36, a second cover portion 37 and a third cover portion 38 which are integrated with each other. Further, the exhaust box 35 includes a main body 39 and a tubular exhaust pipe 40 integrally formed with each other, and an inner box 41 (inner cylinder) and an outer box 42 (outer) which are integrated with the main body 39. It consists of a cylinder. The main body part 39, the inner box part 41, and the outer box part 42 are fixed to the engine 12 in a state of being integrally connected. The exhaust box 35 has a shape that is long in the front-rear direction of the crankshaft and is arranged above the engine 12. Exhaust box
The reinforcing rib 39A is provided between the main body portion 39 and the exhaust pipe portion 40.

That is, as shown in FIGS. 1 to 4, at the exhaust outlet portion 43 (FIG. 3) opening to the combustion chamber of the engine 12, the exhaust gas formed by the exhaust cover 34 and the exhaust pipe portion 40 of the exhaust box 35 is formed. Passage of
An exhaust expansion chamber 45 formed by the body 39 and the inner box 41 of the exhaust box 35, an inner box 41 and an outer box 42 of the exhaust box 35 are sequentially formed via 44A and 44B (first exhaust passage). Exhaust passage 46A
(Third exhaust passage), Exhaust passage 46B (Second exhaust passage), Rubber exhaust hose 47, Exhaust expansion chamber 48, Rubber exhaust hose 49
Each of which is connected. Since the exhaust expansion chamber 48 is long in the front-rear direction, a sufficient volume can be secured, and the exhaust expansion chamber 48 is formed small in the lateral direction, which contributes to making the size of the engine as a whole compact. The exhaust hose 49 extends straight downward from the exhaust expansion chamber 48, then faces rearward, penetrates a rear inner side wall of the hull 11 below the exhaust box 35, and opens in the recess 11A. Note that the exhaust communication passage 44B formed by the exhaust pipe portion 40 projects and opens inside the exhaust expansion chamber 45 by a certain length. According to this exhaust structure, by appropriately setting the length of the exhaust communication passages 44A, 44B, an exhaust pressure wave is applied to the combustion chamber of the engine 12 at an appropriate timing to improve intake charging efficiency, and It is possible to obtain the effect of reducing exhaust noise by the exhaust expansion chambers 45 and 48.

Further, the respective cover portions 36 to 38 of the exhaust cover 34 are water jackets.
50, the main body portion 39 of the exhaust box 35 forms a water jacket 51, the exhaust pipe portion 40 of the exhaust box 35 forms a water jacket 52, and the inner box portion 41 and the outer box portion 42 of the exhaust box 35 are The water jacket 53 is formed. Each water jacket 50-53 communicate with each other,
The cooling water that has passed through the water jacket 33 of the engine 12 is discharged from the water jacket 53 through the water jackets 50 to 52.
The water jacket 53 is located on the exhaust downstream side from the upper end opening 201 of the exhaust passage 46A that is open to the exhaust expansion chamber 45 inside the inner box part 41,
That is, the cooling water can be discharged from the communication portion 55 into the exhaust by communicating with the intermediate portion of the exhaust passages 46A and 46B. That is, the water jet propulsion ship 10 has the following (1)-
It has the exhaust structure of (4).

(1) The first exhaust passage 44 at the exhaust outlet 43 of the engine 12 body
Exhaust expansion chamber 45 communicating with A and 44B, and exhaust expansion chamber 45
Second exhaust passage 46 that communicates with and discharges exhaust gas toward the outside of the ship
B, 47 and around the exhaust expansion chamber 45,
The second exhaust passages 46B, 47 communicate with the second exhaust passages 46B, 47.
It has water jackets 51 and 53 for draining cooling water.

(2) The exhaust expansion chamber 45 is composed of the inner box part 41 and the outer box part 42, and the first exhaust passages 44A and 44B are connected to one end of the exhaust expansion chamber 45 and the inner box part 41 The water jackets 51 and 53 are formed by opening the side end toward the inner surface direction and guiding the cooling water to the space between the inner box part 41 and the outer box part 42.

(3) At the other end of the exhaust expansion chamber 45, the second exhaust passage 46B is connected to the bottom wall of the outer box part 42 and the opening 41A is formed in the bottom wall of the inner box part 41.

(4) Inside the inner box part 41, a vertically extending third exhaust passage 46A is provided, and the wall surface of the third exhaust passage 46A is brought into contact with the inner surface 41B of the other end of the inner box part 41, Exhaust passage 46A
The lower end opening 202 is communicated with the opening 41A opened in the bottom wall of the inner box part 41, and the upper end opening 201 is opened inside the inner wall part.

The exhaust passage 46B communicating with the exhaust expansion chamber 45 is provided in the exhaust box 3
5 extends downward from the lower surface side of the outer box part 42, and an exhaust hose 47 is connected to this extended part. This makes the hull
A space for installing an electrical equipment box 56 containing an ignition coil is secured in a front portion of the inside of 11 with respect to the cooling water box 35. 57 is a spark plug.

The hull 11 is provided with an engine room cover 58 on the upper part of the engine 12 in a detachable manner.

Next, the operation of the above embodiment will be described.

The cooling water obtained by water-cooling the inner box part 41 into which the exhaust gas has been introduced is drained to the second exhaust passages 46B and 47 without passing through the inner box part 41, and then discharged to the outside of the ship.

Here, a vertically extending third exhaust passage 46A is provided inside the inner box portion 41, and the lower end opening 202 of the third exhaust passage 46A is communicated with the opening portion 41A opened at the bottom wall of the inner box portion 41. At the same time, the upper end opening 201 is opened inside the inner box portion 41, so that the cooling water discharged to the second exhaust passages 46B and 47 is the exhaust pressure wave,
Alternatively, even if an attempt is made to flow into the inner box portion 41 due to a change in the attitude of the hull or the like, this is blocked by the third exhaust passage 46A, and the cooling water will not be drawn in or flow into the combustion chamber of the engine 12 main body.

At the other end of the exhaust expansion chamber 45, the second exhaust passages 46B, 47 are connected to the bottom wall of the outer box part 42 and the opening 41A is formed in the bottom wall of the inner box part 41 to exhaust the cooling water. It constitutes the part to be discharged inside. That is, the structure is simplified because it is sufficient to provide the openings 41A on the bottom walls of the outer box part 42 and the inner box part 41 without taking a special drainage structure.

The first exhaust passages 44A, 44B are opened toward the inner surface of the other end of the inner box part 41, and the wall surface of the third exhaust passage 46A provided so as to extend vertically inside the inner box part 41 Since it is brought into contact with the inner surface 41B of the other end of the box portion 41, the first exhaust passage 4
The exhaust gas introduced to the inner box part 41 by 4A and 44B is
After hitting the inner surface 41B of the other side end, the inner box portion 41 is guided by the inner surface of the other side end and flows into the third exhaust passage 46A.

Therefore, even if the vertically extending third exhaust passage 46A is provided inside the inner box portion 41, the exhaust gas can smoothly flow into the third exhaust passage 46A.

The exhaust passage 46B communicating with the exhaust expansion chamber 45 is extended downward from the lower surface side of the exhaust box 35 forming the exhaust expansion chamber 45, so that the front portion of the exhaust box 35 serves as an installation space for the electrical equipment box 56. Effectively usable. Since the exhaust passage does not project to the side of the engine body and extends straight downward from the exhaust box, the width of the engine body becomes smaller. This means that the cross-sectional area of the water-jacket propulsion ship is reduced, and the hull resistance can be reduced. Further, since the exhaust expansion chamber has a sufficient volume, it is effective in reducing noise.

By the way, in the water jet propulsion ship 10 which is long in the longitudinal direction and has a watertight structure, the water jet propulsion ship 10 may fall or rotate during navigation. At this time, in the above-described embodiment, there is a possibility that the cooling water may infiltrate and accumulate in the lower portion of the exhaust expansion chamber 45 from the exhaust introduction portion 54 of the exhaust passage 46A. This may result in corrosion of the infiltrated water retention section or intrusion of the exhaust pipe 44B to the engine side when the number of falls is excessive.

Therefore, in the practice of the present invention, as shown in FIG. 7 and FIG. 9, the lower portion of the exhaust expansion chamber 45 and the water jacket 53 are provided with small holes.
Assuming that 101 and 102 communicate with each other, the accumulated water in the lower portion of the exhaust expansion chamber 45 is the communication small hole 10 for the pressure of the exhaust gas inside the exhaust expansion chamber 45 or the water flowing through the water jacket 53.
Exhaust expansion chamber 45 due to either suction action at 1, 102
Will be leaked to the outside. 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 water sucking action in the communication small hole 102 can be used more effectively. . Further, as shown in FIG. 7, the check valve 103 is provided at the water jacket side opening of the small hole 101.
With the above arrangement, it is possible to reliably prevent the possibility that the water flowing through the water jacket 53 will flow back into the exhaust expansion chamber 45.

Further, in the practice of the present invention, as shown in FIG. 8, even when the lower portion of the exhaust expansion chamber 45 and the exhaust passage 46A are communicated with each other through the small hole 104, the accumulated water in the lower portion of the exhaust expansion chamber is The pressure of the exhaust gas inside the exhaust expansion chamber 45 or the suction action of the exhaust gas flowing through the exhaust passage 46A at the communication small hole 104 can be caused to flow out of the exhaust expansion chamber 45.

[Advantages of the Invention] As described above, according to the present invention, when the water jacket is provided around the exhaust expansion chamber, the exhaust structure is simplified and the cooling water is burned in the engine body while ensuring a smooth flow of the exhaust. It is possible to prevent entry into the room.

[Brief description of drawings]

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 a main part of FIG. 1, and FIG. 3 is III-III of FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3 and is partially broken, and FIG. 5 is a sectional view showing a part of the exhaust box.
5 is an end view of FIG. 5, FIG. 7 is a cross-sectional view of an essential part showing a modification of the present invention, FIG. 8 is a cross-sectional view of an essential part of another modification of the present invention, and FIG. It is a principal part sectional view which shows another modification. 10 ... Water jet propulsion ship, 12 ... Engine, 35 ... Exhaust box, 41 ... Inner box part (inner cylinder), 41A ... Opening part, 41B ... Inner surface on the other side, 42 ... Outer box part (Outer cylinder), 43 ... Exhaust outlet, 44A, 44B ... First exhaust passage, 45 ... Exhaust expansion chamber, 46A ... Third exhaust passage, 46B,
47 …… Second exhaust passage, 51-53 …… Water jacket, 201…
… Top opening, 202… bottom opening.

Claims (1)

[Claims] 1. An exhaust expansion chamber that communicates with an exhaust outlet of an engine body through a first exhaust passage, a second exhaust passage that communicates with the exhaust expansion chamber and discharges exhaust gas toward the outboard, and exhaust expansion. In an exhaust structure of a watercraft propulsion device, which is provided around the chamber and has a water jacket communicating with the second exhaust passage and draining cooling water to the second exhaust passage, the exhaust expansion chamber includes an inner expansion chamber and an outer expansion chamber. A cylinder, the first exhaust passage is connected to one end of the exhaust expansion chamber, opens toward the inner surface of the other end of the inner cylinder, and is cooled in the space between the inner cylinder and the outer cylinder. Water is guided to form a water jacket, the second exhaust passage is connected to the bottom wall of the outer cylinder at the other end of the exhaust expansion chamber, and an opening is formed in the bottom wall of the inner cylinder. A third exhaust passage extending vertically is provided and the wall surface of the third exhaust passage is provided on the other side of the inner cylinder. Exhaust of a marine vessel propulsion device, characterized in that the lower end opening of the third exhaust passage is brought into contact with the inner surface of the end, the lower end opening of the third exhaust passage is communicated with the opening opening in the bottom wall of the inner cylinder, and the upper end opening is opened inside the inner cylinder. Construction.