JPH0648389A - Exhauster of outboard engine - Google Patents

Abstract

PURPOSE:To decrease noise by forming the release expansion chamber sunk in water of a dropping cooling water storage chamber between inner walls of an exhaust tube housing and a drive shaft housing, for communicating it with a main expansion chamber and a release exhaust port. CONSTITUTION:An exhaust tube housing 33 is arranged in a drive shaft housing 21, and a water chamber 37 for storing dropping cooling water 38 is formed between both housings 21, 33. Moreover, a release expansion chamber 46 is formed so as to be sunk into water 38 in this water chamber 37. This release expansion chamber 46 is communicated with a main expansion chamber 34 through a release second hole 47 formed in the exhaust tube housing 33. At the same time, the release expansion chamber is also communicated with an release exhaust port 49 formed on the upper part of a drive shaft housing 21 through the water chamber 37 and a sub expansion chamber 48.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for outboard motors.

[0002]

As shown in FIG. 12, an outboard motor has an engine 2 mounted on an upper portion of a drive shaft housing 1. The engine 2 is covered with an engine cover 3, while the lower portion of the drive shaft housing 1 is covered. The gear case 4 is joined, a propeller shaft (not shown) is supported by the gear case 4, and the propeller 5 is attached to the propeller shaft. The outboard motor is attached to the tail of the hull 17 by the clamp bracket 6, and the propeller 5 is rotated by the driving force of the engine 2 to propel the hull 17.

In such an outboard motor, the inside of the engine 2
The exhaust (main exhaust) from the engine at high speed is
After passing through the engine holder 7, the exhaust manifold 8 and the exhaust tube 9 shown in FIG. 13, the exhaust tube housing 10 expands, and from the inside of the exhaust tube housing 10 through the gear case 4 to the main discharge port 11 of the boss of the propeller 5 underwater. Is discharged to.

When the engine 2 is idling,
Exhaust gas (release exhaust gas) that has reached the inside of the exhaust tube housing 10 during low-speed rotation or normal reverse operation passes through a release exhaust passage (described later) of the exhaust manifold 8 and is discharged between the exhaust manifold 8 and the drive shaft housing 1. , Is also discharged into the atmosphere from the release discharge port 12 formed in the drive shaft housing 1.

The release exhaust passage is composed of ribs 13A, 13B and 13C formed on the exhaust manifold 8, as shown in FIGS. In other words, in the release exhaust passage, the exhaust gas flows in from the exhaust gas inlet port 14 and is rotated above the rib 13A, so that the rib 13B
To flow out from the exhaust outlet 15. Exhaust gas flows through the release exhaust passage while cooling water falling water 1 temporarily stored in the exhaust manifold 8 is discharged.
Energy is absorbed by 6 and is silenced.

[0006]

In order to muffle the exhaust gas as described above, the exhaust manifold 8 must be installed as a dedicated part for mending the release exhaust gas,
The cost will rise.

When the engine speed is increased during the release operation of the outboard motor, the pressure of the exhaust gas rises. Therefore, the exhaust gas that reaches the exhaust tube housing 10 passes through the gear case 4 and the main discharge port of the propeller 5. It is discharged from 11. However, during reverse operation, the exhaust gas from the main outlet 11 may be caught in the blades of the propeller 5, which may reduce the reverse thrust.

The present invention has been made in view of the above circumstances, and the invention according to claim 1 provides an exhaust system for an outboard motor capable of muffling release exhaust at low cost. It is an object of the present invention to provide an exhaust device for an outboard motor capable of improving reversing thrust during grounding operation.

[0009]

According to a first aspect of the present invention, an engine is mounted above a drive shaft housing via an engine holder, and an exhaust tube for guiding exhaust gas from the engine is introduced into the drive shaft housing. An exhaust tube housing covering the exhaust tube is installed in the drive shaft housing to form a main expansion chamber for expanding exhaust gas discharged from the exhaust tube, and inner walls of the exhaust tube housing and the drive shaft housing. And an exhaust device for an outboard motor in which a water chamber for storing cooling water is stored between the exhaust tube housing and the inner wall of the drive shaft housing. Submerged in A release expansion chamber that is capable of functioning is formed, and this release expansion chamber communicates with the main expansion chamber and also with the release exhaust port formed in the upper portion of the drive shaft housing through the water chamber. It is a feature.

Further, according to a second aspect of the present invention, the engine is mounted above the drive shaft housing via an engine holder, and an exhaust tube that guides exhaust gas from the engine extends into the drive shaft housing to drive the drive shaft housing. An exhaust tube housing that covers the exhaust tube is installed in the shaft housing, and the inside of the drive shaft housing passes through the exhaust passage in the gear case that is connected to the drive shaft housing and the propeller installed in the gear case. In the exhaust device for an outboard motor, which is communicated with the main exhaust port of the boss portion of the above, in the gear case, a water flow chamber extending so as to straddle the blade of the propeller is formed above the propeller, and the exhaust tube is formed. Downstream of the housing and the water flow chamber It is characterized in that configured in communication.

[0011]

According to the first aspect of the present invention, the exhaust gas (release exhaust gas) guided from the exhaust tube to the main expansion chamber during the low speed rotation of the outboard motor, during the idling rotation of the outboard motor, or during the normal reverse operation is released by the sub expansion. After passing through the chamber and passing through the cooling water falling in the water chamber, the energy is absorbed and the sound is silenced, and then discharged from the release exhaust port.

The release exhaust is silenced by utilizing the cooling water falling outside the water chamber constituted by the inner wall of the drive shaft housing and the exhaust tube housing. Therefore, a dedicated part for silencing the release exhaust is required. do not do. Therefore, the exhaust gas can be silenced without increasing the cost.

According to the second aspect of the present invention, when the engine speed is increased during the reverse operation, the pressure of the exhaust gas increases, and the exhaust gas is discharged from the exhaust tube into the exhaust tube housing and then the water flow chamber. It is discharged into the stream of water and silenced. Since the water flow chamber is configured to extend so as to straddle the blades of the propeller, the exhaust gas discharged into the water in the water flow chamber is not caught by the blades of the propeller. Therefore, the reverse thrust during the reverse operation of the outboard motor can be improved.

[0014]

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

FIG. 1 is a side view showing a part of a drive shaft housing of an outboard motor in which a first embodiment of an exhaust system for an outboard motor according to the present invention is applied.

Drive shaft housing 21 of the outboard motor
An engine holder 22 is installed in the upper part of the inside, and an engine (not shown) is mounted on the engine holder 22. This engine is covered by an engine cover 23. The gear case 24 is joined to the lower portion of the drive shaft housing 21. Further, a swivel bracket 25 and a clamp bracket 26 are arranged in front of the drive shaft housing 21. These brackets 2
Through 5 and 26, the outboard motor is rotatably mounted horizontally and vertically on a hull (not shown).

Now, in front of the drive shaft housing 21, a crankshaft of an engine (not shown) is provided.
A drive shaft 27 connected to is disposed in the vertical direction. The drive shaft 27 is a propeller shaft (not shown) via a power transmission mechanism in the gear case 24.
Power is transmitted to and the propeller is rotated.

The water pump 28 disposed under the drive shaft housing 21 has a drive shaft 27.
Driven by the water, the water is sucked from the water inlet 29 of the gear case 24 and introduced into the water tube 30 as cooling water. This water tube 30 is used for the drive shaft 2
7 extends in the vertical direction along the dlife shaft 27, penetrates the engine holder 22, and guides cooling water to the engine.

On the other hand, an exhaust tube 32 is fixed to the lower surface of the engine holder 22 at the central portion and the rear side inside the drive shaft housing 21, and an exhaust tube housing 33 is fixed so as to surround the exhaust tube 32. The exhaust tube housing 33 causes the inside thereof to function as a main expansion chamber for expanding the exhaust gas provided from the exhaust tube 32.

The main expansion chamber 34 is communicated with an exhaust passage 35 formed in the gear case 24.
Are communicated with an exhaust passage of a propeller boss (not shown). Then, a main exhaust port (not shown) is formed in the propeller boss.

Therefore, the exhaust gas (main exhaust gas A) collected in the exhaust tube 32 when the engine is running at high speeds
After expanding in the main expansion chamber 34, the gear case 24
After passing through the exhaust passage 35 and the exhaust passage of the propeller boss section, the sound is discharged from the main exhaust port into the water and silenced. The water surface inside the outboard motor is at the L position when the engine is rotating at a high speed.

On the other hand, an inner wall 36 is formed in the drive shaft housing 21 so as to cover the exhaust tube housing 33, and a water chamber 37 is formed between the inner wall 36 and the exhaust tube housing 33. In the water chamber 37, the cooling water drop water 38 after cooling the engine is temporarily stored. An overflow passage 40 is formed between the inner wall 36 and the outer wall 39 of the drive shaft housing 21. The cooling water falling water 38 stored in the water chamber 37 overflows from the weir 41 at the upper end of the inner wall 36 into the overflow passage 40. The cooling water that has fallen into the overflow passage 40 is discharged from the drain port 42 of the gear case 24.
Discharged into water.

In the exhaust tube 32, a release first hole 43 is opened above the water surface M in the outboard motor during engine idling rotation, low rotation or normal reverse operation. Further, as shown in FIGS. 1 and 2, a rib 44 having a U-shape in a side view is provided so as to project from the outer surface of the exhaust tube housing 33.
An elastic seal, such as a rubber seal 45, is fitted to the tip portion of 4. The rubber seal 45 comes into contact with the inner surface of the inner wall 36 of the drive shaft housing 21, whereby the rib 4
4, exhaust tube housing 33 and inner wall 3
Surrounded by 6 is a release expansion chamber 46.

As shown in FIG. 3, the release expansion chamber 46 is a space that opens downward in the figure. Also,
The exhaust tube housing 33 has a release second chamber that connects the release expansion chamber 46 and the main expansion chamber 34 to each other.
The hole 47 is opened. The release second hole 47 is set above the water surface M. The drive shaft housing 21 and the engine holder 2 are provided above the water chamber 37.
The sub expansion chamber 48 is formed by 2. The sub-expansion chamber 48 communicates with the water chamber 37 and also communicates with a release exhaust port 49 opened at the upper portion of the inner wall 39 of the drive shaft housing 21.

Therefore, as shown in FIG. 1, the exhaust gas (release exhaust B) reaching the exhaust tube 32 from the engine at the time of low engine speed, idling speed or normal reverse operation is released from the release first hole 43 to the main expansion. It is introduced into the chamber 34 and expanded, and further introduced into the release expansion chamber 46 through the release second hole 47 and expanded, and the inside of the water chamber 37 is cooled from the lower opening of the release expansion chamber 46 as shown in FIG. Is released into the falling water 38,
Energy is absorbed and silenced. The release exhaust B discharged into the cooling water falling water 38 in the water chamber 37 becomes bubbles and rises, reaches the sub expansion chamber 48 and expands, and is discharged from the release exhaust port 49 into the atmosphere.

According to the first embodiment described above, the release exhaust B
However, after reaching the inside of the release expansion chamber 46, the water is guided into the cooling water falling water 38 in the water chamber 37, and the cooling water falling water 38 deprives the user of energy and silences the sound. Since the cooling water drop water 38 is always stored in the water chamber 37, a dedicated part (exhaust manifold 8 of the conventional example) for storing the cooling water drop water 38 for silencing the release exhaust is not required. As a result, the release exhaust B can be silenced at low cost.

Further, in the conventional example, the depth h (FIG. 15) of the cooling water falling water 38 required for silencing the release exhaust cannot be set sufficiently due to the structure of the exhaust manifold 8, but in the first embodiment, The depth H of the cooling water falling water shown in FIG. 3 can be arbitrarily set. That is, the depth H of the cooling water falling water 38 can be easily changed by changing the vertical length of the rubber seal 45 fitted to the rib 44, so that the release exhaust B can be surely silenced. .

Further, the exhaust tube housing 33 and the inner wall 36 of the drive shaft housing 21 are provided.
Since an elastic seal such as a rubber seal 45 is interposed between the rubber seal 45 and the rubber seal 45, horizontal vibration of the exhaust tube housing 33 can be reduced.

FIG. 4 is a side view showing a notch of a drive shaft housing of an outboard motor to which the second embodiment of the outboard motor exhaust system according to the present invention is applied. In the second embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, as shown in FIG. 5, the drive shaft housing 50 is provided on its outer surface with a rib 51 projecting from the side, and a plate 52 is fixed to the upper surface of the rib 51. Thus, the release expansion chamber 53 is configured as shown in FIG. The drive shaft housing 21 is formed with a release second hole 54 that connects the release expansion chamber 53 and the main expansion chamber 34. Further, the plate 52 is formed with a release third hole 55 that connects the release expansion chamber 53 and the water chamber 37.

Therefore, in the second embodiment, the release exhaust B in the exhaust tube 32 expands from the release first hole 43 into the main expansion chamber 34,
From the second release hole 54, the release expansion chamber 53 is expanded. Release exhaust B in the release expansion chamber 53
Is released from the third release hole 55 into the cooling water falling water 38 in the water chamber 37, and the energy is absorbed and silenced.
Of these, the release exhaust reaches the sub-expansion chamber 48, expands, and is discharged from the release exhaust hole 49 into the atmosphere.

Also in the second embodiment, after the release exhaust B is guided to the release expansion chamber 53, the release exhaust B is discharged into the cooling water falling water 38 always stored in the water chamber 37 and is silenced. No special parts are required to silence the exhaust B. As a result, the release exhaust B can be silenced at low cost.

Further, in the second embodiment, the release third
Since the depth H '(FIG. 6) of the cooling water falling water 38 through which the release exhaust B discharged from the hole 55 passes can be easily changed by changing the position of the release third hole 55, the noise of the release exhaust B can be silenced. It can be implemented reliably.

FIG. 7 is a side view showing a part of a drive shaft housing and a gear case of an outboard motor exhaust system according to the present invention and an outboard motor to which the third embodiment is applied. In the third embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the third embodiment, the exhaust tube housing 60 is the drive shaft housing 61.
An exhaust passage 62 is formed in the upper part and the central part of the drive shaft housing 61 in the longitudinal direction of the drive shaft housing 61. Exhaust passage 6 of this drive shaft housing 61
2 communicates with the main expansion chamber 34 formed by the exhaust tube housing 60, and also communicates with the exhaust passage 35 of the gear case 63.

Further, the main exhaust A in the exhaust tube 32 expands in the main expansion chamber 34, then is guided to the inside of the propeller boss portion 65 of the propeller 64 through the exhaust passages 62 and 35, and then from the main exhaust port 66. Is discharged.

The exhaust tube 32 has a first
The release first hole 43 as in the embodiment is not opened, and the first and second release holes 43 are also provided between the exhaust tube housing 65 and the inner wall 36 of the drive shaft housing 61.
Since the release expansion chambers 46 and 53 as in the embodiment are not provided, the release exhaust B in the exhaust tube 32 is discharged from the inside of the exhaust tube 32 into the water below the water surface M and is silenced, and then the main expansion chamber. The gas is discharged from 43 through the sub expansion chamber 48 to the atmosphere through the release exhaust port 49.

The lower portion of the drive shaft housing 61 and the gear case 63 are joined together to form a reverse expansion chamber 67. The drive shaft housing 61 is provided with a reverse first hole 68 that connects the reverse expansion chamber 67 and the exhaust passage 62. Also, the gear case 63
In the upper part of the propeller 64, a water flow chamber 70 extending so as to straddle the blades 69 of the propeller 64 is formed.

The inlet 71 of the water flow chamber 70 is shown in FIG.
The elevation angle θ is set as shown in (B) and (B), and the water flow w in the laminar flow state is configured to flow in the water flow chamber 70.
In addition, W in FIGS. 8A and 8B represents a water flow generated from the propeller 2. Further, the gear case 63 has a reverse second passage that connects the water flow chamber 70 and the reverse expansion chamber 67.
A hole 72 is provided. The reverse second hole 72 is set at a position where a dynamic pressure does not act in the water flow chamber 70 and a negative pressure is produced by the Venturi effect.

In the third embodiment, the release exhaust B is discharged from the release exhaust port 49 as described above during the normal reverse operation. However, when the engine speed is increased and the exhaust pressure is increased during the reverse operation, the water surface inside the outboard motor is lowered to the N position, and this high pressure exhaust C is guided from the exhaust tube 32 into the main expansion chamber 34 and expanded. Further, the reverse first hole 68 is guided into the reverse expansion chamber 67 and expands again. Reverse expansion chamber 67
The high-pressure exhaust C guided to is discharged from the reverse second hole 72 into the water flow w in the water flow chamber 70, energy is absorbed and the sound is silenced.

At this time, since the water flow chamber 70 is extended so as to straddle the blades 69 of the propeller 64, the bubble-shaped high-pressure exhaust C discharged into the water flow w is, as shown in FIG. 8 (A), The propeller 64 is moved to the front side of the blade 69 and is not caught by the blade 69. Therefore, it is possible to prevent the reverse thrust from decreasing.

Further, even when the vehicle is suddenly started in the forward operation state, the exhaust pressure increases, and the high pressure exhaust C at this time is
After being guided to the reverse expansion chamber 67, it is temporarily discharged from the second reverse hole 70 into the water flow w in the water flow chamber 70. After this, the high-pressure exhaust C, as shown in FIG.
4 is guided to the rear of the blade 69, so that it is not caught in the blade 69. As a result, exhaust gas can be quickly discharged at the time of sudden start, and at this time, the forward thrust is not reduced, so that the responsiveness of sudden start can be improved.

In the above embodiment, the water flow chamber 70 is integrally formed with the gear case 63, but as shown in FIG. 9, the water flow chamber 70 is composed of the gear case 63 and the cover 73. Good. In this case, the cover 73
It is attached to the gear case 63 together with the trim tab 74. Further, as shown in FIGS. 10 and 11, the water flow chamber 70 may be configured as a pipe 75 having an elliptical cross section fixed to the lower portion of the gear case 63.

[0044]

As described above, according to the first aspect of the invention, the cooling water falling water stored in the water chamber is submerged in the water chamber between the exhaust tube housing and the inner wall of the drive shaft housing. A possible release expansion chamber is formed, and this release expansion chamber is connected to the main expansion chamber and to the release exhaust port formed in the upper part of the drive shaft housing via the water chamber, By using the cooling water that has cooled in the water chamber, the release exhaust can be silenced at low cost.

According to the second aspect of the present invention, a water flow chamber is formed above the propeller in the gear case so as to extend over the blades of the propeller, and the water flow chamber communicates with the downstream side of the exhaust tube housing. Since the exhaust is not caught in the blades of the propeller during the reverse operation, the reverse thrust during the reverse operation can be improved.

[Brief description of drawings]

FIG. 1 is a side view showing a notch of a drive shaft housing of an outboard motor to which a first embodiment of an outboard motor exhaust system according to the present invention is applied.

FIG. 2 is a perspective view showing a part of the exhaust tube housing of FIG.

FIG. 3 is a view on arrow III in FIG.

FIG. 4 is a side view showing a notch of a drive shaft housing of an outboard motor to which a second embodiment of the exhaust system for an outboard motor according to the present invention is applied.

5 is a perspective view showing a part of the exhaust tube housing of FIG.

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a side view showing a drive shaft housing and a gear case of an outboard motor, to which the third embodiment of the outboard motor exhaust system according to the present invention is applied, with a part thereof broken away.

8 shows the flow states of high-pressure exhaust C and water flow w in the water flow chamber of FIG. 7, (A) during reverse operation, (B).
Is a diagram showing a case of sudden start.

9 is a cross-sectional view showing a first modification of the water flow chamber of FIG.

10 is a sectional view showing a second modification of the water flow chamber of FIG.

11 is a cross-sectional view taken along the line XI-XI of FIG.

FIG. 12 is an overall side view showing an outboard motor to which a conventional exhaust system is applied.

FIG. 13 is a side view showing a drive shaft housing and a gear case in the outboard motor of FIG.

14 is a perspective view of the exhaust manifold in FIG.

15 is a sectional view taken along line XV-XV in FIG.

[Explanation of symbols] 21 Drive shaft housing 22 Engine holder 32 Exhaust tube 33 Exhaust tube housing 34 Main expansion chamber 35 Exhaust passage 36 Inner wall 37 Water chamber 38 Cooling water falling water 46 Release expansion chamber 47 Release second hole 48 Sub expansion chamber 49 Release exhaust hole 50 Drive shaft housing 53 Release expansion chamber 54 Release second hole 55 Release third hole 61 Drive shaft housing 63 Gear case 64 Propeller 65 Propeller boss section 66 Main exhaust port 67 Reverse expansion chamber 68 Reverse first hole 69 Blade 70 Water flow chamber 72 Reverse second hole

Claims (2)

[Claims] 1. An engine is mounted above a drive shaft housing via an engine holder, and an exhaust tube for guiding exhaust gas from the engine extends into the drive shaft housing, and the exhaust tube is provided in the drive shaft housing. A main expansion chamber that expands the exhaust gas discharged from the exhaust tube is formed by installing an exhaust tube housing that covers the water, and cooling water that collects the falling water is stored between the exhaust tube housing and the inner wall of the drive shaft housing. In an outboard motor exhaust system having a chamber, a release expansion chamber is formed between the exhaust tube housing and the inner wall of the drive shaft housing, the release expansion chamber being submersible in the cooling water falling in the water chamber. The expansion chamber is communicated with the main expansion chamber, and is also communicated with a release exhaust port formed in an upper portion of the drive shaft housing through the water chamber. . 2. An engine is mounted above a drive shaft housing via an engine holder, and an exhaust tube for guiding exhaust gas from the engine extends into the drive shaft housing, and the exhaust tube is provided in the drive shaft housing. An exhaust tube housing for covering is installed, and the inside of the drive shaft housing communicates with the main exhaust port of the boss part of the propeller arranged in this gear case through the exhaust passage in the gear case connected to this drive shaft housing. In the exhaust device for an outboard motor described above, in the gear case, a water flow chamber extending so as to straddle the blades of the propeller is formed above the propeller, and the downstream side of the exhaust tube housing and the water flow chamber are formed. Characterized by being configured in communication Exhaust system for outboard motors.