JP2001090531A - Exhaust passage structure for outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an exhaust noise eliminating effect while securing maintainability for an exhaust passage of an outboard engine. SOLUTION: A split face 481 of an exhaust passage forming member 48 is coupled to a split face 412 provided in a rear part of an oil case 41 put between an engine block 11 and an extension case 42. A main exhaust expansion chamber e3 and a sub-exhaust expansion chamber e7 are formed between the member 48 and the oil case 41, and exhaust supplied from the first exhaust passage e1 of the oil case 41 is discharged to the second exhaust passage e5 of the oil case 41 through the chamber e3. One portion of the exhaust in the chamber e3 is discharged into the air from an exhaust outlet e8 through a communication port e6 and the chamber e7. Maintenance is conducted only by separating the member 48 from the oil case 41 to expose the chambers e3, e7 without diassembling the case 41 so as to remarkably enhance maitainability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust passage structure for an outboard motor in which at least a part of an exhaust passage is formed integrally with a case housing a drive shaft for transmitting a driving force of an engine to a propeller.

[0002]

2. Description of the Related Art Generally, an outboard motor includes an engine room for accommodating an engine, and a case body extending downward from the engine room for accommodating a drive shaft driven by the engine. Exhaust gas is guided down the interior of the case body to enhance the silencing effect and is discharged into water. During idling operation of the engine, a part of the exhaust gas is branched and discharged into the air to reduce the back pressure.

[0003] In such an outboard motor, an exhaust passage having an effect of silencing by an exhaust expansion chamber having an entrance and exit is disclosed in Japanese Patent Application Laid-Open No. Hei 8-100625.

[0004]

By the way, if the exhaust expansion chamber is formed integrally with the case body of the outboard motor, it is necessary to change or replace the entire case body, which is a large part, in order to adjust the noise reduction effect. However, there is a problem that the cost is greatly increased.

[0005] The case body of the outboard motor generally comprises a cylindrical extension case, a mount case connected to an upper end of the extension case to support an engine block, and a gear case connected to a lower end of the extension case. If the exhaust expansion chamber is formed integrally with the case body, it is necessary to disassemble the case body when performing maintenance. However, since each case constituting the case body is a heavy and large part and is supported via an elastic mounting device on a mounting bracket supporting the outboard motor to the hull, it is extremely troublesome to separate them. Ergonomic work is required, and there is a problem that maintainability is reduced.

In particular, when the outboard motor has a four-stroke engine and the oil pan is provided inside the case body, the oil pan and the exhaust expansion chamber interfere with each other to sufficiently increase the volume of both. There is a problem that it is difficult to secure.

The present invention has been made in view of the above circumstances, and has as its object to enhance the exhaust noise silencing effect while ensuring the maintainability of the exhaust passage of an outboard motor.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, at least an exhaust passage is provided in a case body accommodating a drive shaft for transmitting a driving force of an engine to a propeller. In an exhaust passage structure of an outboard motor, a part of which is integrally formed, an opening of the exhaust passage is formed in a side wall of a case body, and a lid body and a case body detachably coupled to cover the opening. An exhaust passage structure for an outboard motor, wherein an exhaust passage constituting an exhaust silencer is formed between the exhaust passages.

According to the above structure, the exhaust passage constituting the exhaust silencer is formed between the lid and the case which are detachably connected so as to cover the opening of the side wall of the case. As compared with the case where the exhaust silencer is formed inside the body, the degree of freedom in designing the exhaust silencer can be increased and the exhaust silencer can be enhanced. Moreover, it is possible to perform maintenance by exposing the exhaust passage only by separating the lid from the case body without disassembling the case body, thereby greatly improving the maintainability.

According to the second aspect of the present invention,
In addition to the configuration of the first aspect, there is proposed an exhaust passage structure for an outboard motor, in which an oil pan for storing engine lubricating oil is integrally formed inside a case body.

According to the above construction, even when the oil pan for storing the lubricating oil of the engine is integrally formed inside the case body, the lid body is separated from the case body without being obstructed by the oil pan. The maintenance of the exhaust passage can be performed only by using the oil pan and the interference between the oil pan and the exhaust silencer can be avoided, and the volumes of both can be sufficiently secured.

The oil case 41 of the embodiment corresponds to the case body of the present invention, the exhaust passage forming member 48 of the embodiment corresponds to the lid of the present invention, and the communication ports e ₂ , e ₄ of the embodiment correspond to the case. This corresponds to the opening of the present invention.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 7 show a first embodiment of the present invention. FIG. 1 is an overall side view of an outboard motor, FIG. 2 is an enlarged sectional view of a main part of FIG. 1, and FIG. 3 is a sectional view taken along line 3-3, FIG. 4 is an enlarged view taken along line 4-4 in FIG. 1, FIG. 5 is an enlarged view taken along line 6-6 in FIG. 5, FIG. FIG. 7 is a view taken along line 7-7 of FIG. 5.

As shown in FIGS. 1-3, the upper part of the outboard motor O
The two-cylinder four-cycle engine E mounted on the
Case 11₁And two upper and lower cylinder bores 11_Two, 1
1_TwoEngine block 11 integrally provided with
A cylinder head 12 connected to a block 11;
A head cover 13 coupled to the
The two series formed in the engine block 11
Daboa 11_Two, 11 _TwoTwo slidable fittings
Ston 14,14 supported by engine block 11
Connecting rods 16 and 1 are connected to the crankshaft 15
6 are connected.

A generator 17 and a recoil starter 18 are coaxially provided at an axial end of a crankshaft 15 projecting upward from the engine block 11. A camshaft 20 is supported in a valve operating chamber 19 defined between the cylinder head 12 and the head cover 13, and a cam pulley 21 provided at an upper end thereof and a crank pulley 22 provided above the crankshaft 15 form a timing belt 23.
Connected by An intake valve 26 and an exhaust valve 27 for opening and closing an intake port 24 and an exhaust port 25 formed in the cylinder head 12, respectively, are connected to the camshaft 20 via an intake rocker arm 28 and an exhaust rocker arm 29, respectively. An intake silencer 30, a choke valve 31, and a variable venturi-type carburetor 32 arranged on the right side of the engine E are connected to the intake port 24.

[0017] axis of the crankshaft 15 is disposed vertically, and cylinder bore 11 _2, 11 ₂ of the axes,
Crankcase 11 ₁ side cylinder head 12 side facing forward is disposed in the longitudinal direction to face backward. The crank phases of the two pistons 14, 14 are the same,
The ignition timing is shifted by 360 °. The crankshaft 15 is provided with counterweights 15 ₁ ... Having a balance ratio of 100% against the reciprocating mass of the pistons 14, 14.

The upper surface of the oil case 41 is connected to the lower surface of the engine E having the above structure, the upper surface of the extension case 42 is connected to the lower surface of the oil case 41, and the upper surface of the gear case 43 is connected to the lower surface of the extension case 42. You. The outer periphery of the oil case 41 and the outer periphery of the lower half of the engine E are
The upper half of the engine E is covered with an engine cover 45 connected to the upper end of the under cover 44.

As is apparent from FIG.
Numeral ₁ is integrally provided with an oil pan 41 _{1, in} which a suction pipe 47 having an oil strainer 46 is housed. An exhaust passage forming member 48 is connected to the rear surface of the oil case 41, and the extension case 42
Inside of the exhaust expansion chamber 49 is defined through the bulkhead 42 _1.

A drive shaft 50 connected to the lower end of the crankshaft 15 extends downward through a drive shaft chamber 51 formed in the extension case 42 through the oil case 41 and has a propeller 52 at the rear end. Is connected to a front end of a propeller shaft 53 supported in the front-rear direction via a forward-reverse switching mechanism 54.

A mounting bracket 55 for detachably mounting the outboard motor O to the hull S includes an inverted J-shaped mounting bracket body 56 and a push screw 57 screwed to the mounting bracket body 56. A front end of a swing arm 59 is pivotally supported on the mounting bracket body 56 via a fulcrum pin 58, and a pipe-shaped swivel case 60 is integrally connected to a rear end of the swing arm 59. Mounting bracket body 5
A number of pin holes 56 ₁ ... is provided at the 6, pin holes 56 ₁ either of the pin holes formed in locking plate 60 ₁ fixed to the swivel case 60 mounting bracket body 56
.. Can be adjusted by adjusting the tilt angle of the outboard motor O around the fulcrum pin 58.

A swivel shaft 62, which is rotatably fitted inside the swivel case 60, has a mount frame 63 and a center frame 6 at its upper and lower ends, respectively.
4 is provided. The upper mount frame 63 is connected to the oil case 41 via a pair of left and right upper mounts 65, 65.
The lower mount block 64 is elastically connected to the extension case 42 via the lower mount 66. A steering handle 67 is fixed to the front end of the oil case 41.
The oil case 41 is
Can be swung left and right around the swivel shaft 62 to steer the outboard motor O.

As is clear from FIGS. 2 and 4, the cooling water pumped by a cooling water pump (not shown) is supplied to cooling water passages w ₁ and w ₂ formed on the mating surface of the engine block 11 and the oil case 41. And branched from there to be supplied to the engine block 11 and the cylinder head 12 (see arrow b in FIG. 4). The cooling water that has cooled the engine block 11 and the cylinder head 12 is supplied to a cooling water passage w ₃ formed on the lower surface of the engine block 11.
Is supplied (see arrow c in FIG. 4), it is discharged to the inside of the extension case 42 through the cooling water passage w ₄ formed therefrom in the oil case 41.

[0024] As is apparent from FIGS. 5-7, the exhaust passage member 48, the split surface 48 ₁ formed on its front face being in contact with the split surfaces 41 ₂ formed on the rear surface of the oil case 41 Are connected to the oil case 41 with six bolts 71. Exhaust gas discharged from the exhaust port 25 of the engine E flows from the main exhaust passage 11 ₃ formed inside the engine block 11 to the first main exhaust passage e ₁ formed in the oil case 41 (arrow a see FIG. 4 ), The main exhaust expansion chamber e ₃ formed so as to pass through the communication port e ₂ and be sandwiched between the exhaust passage forming member 48 and the oil case 41.
Flows into. The exhaust gas in the main exhaust expansion chamber e ₃ is connected to the communication port e.
₄ passes through the flow into the second main exhaust passage e ₅ formed in the oil case 41, extension case 42 from which
Through the exhaust expansion chamber 49, the inside of the gear case 43, and the hollow around the propeller shaft 53, which will be described later. On the other hand, the main exhaust expansion chamber e _{3 of} the exhaust passage forming member 48
Some of the exhaust gases of internal flows into auxiliary exhaust expansion chamber e ₇ formed so as to be sandwiched between passes through the communication port e ₆ exhaust passage member 48 and the oil case 41, the exhaust from which outlet e ₈ Through the air into the air. Sub exhaust expansion chamber e ₇
The lower end, there to accumulated water drain hole e ₉ for discharging the second main exhaust passage e ₅ of the oil case 41 is formed. The main exhaust expansion chamber e ₃ and the sub exhaust expansion chamber e ₇ communicate with each other via a pressure relief hole e ₁₀ .

As described above, the oil case 41 and its side
A main exhaust expansion is formed between the exhaust passage forming member 48 and the exhaust passage
Zhang room e_ThreeAnd auxiliary exhaust expansion chamber e₇Formed, so narrow
When forming an exhaust expansion chamber inside a simple oil case 41
The exhaust expansion chamber has more design freedom compared to
The sound effect can be enhanced. Moreover, the oil case 41
To the engine block 11 or the extension case 42
Without separating the exhaust passage forming member 48 from the oil.
Just by separating from the case 41, the main exhaust expansion chamber e _Threeand
Sub exhaust expansion chamber e₇To perform maintenance by exposing
Is possible, and the maintainability is greatly improved. Change
The main exhaust expansion chamber e_ThreeAnd auxiliary exhaust expansion chamber e₇Is oil
Oil pan 41 provided inside case 41₁Interfere with
Oil pan 41₁To secure the volume of
Exhaust expansion chamber e_ThreeAnd auxiliary exhaust expansion chamber e₇To secure the volume of
Can be compatible.

Next, a second embodiment of the present invention will be described with reference to FIGS.

The second embodiment is different from the first embodiment in the structure of the exhaust passage, an exhaust gas discharged from the exhaust port 25, the oil case 41 from the main exhaust passage 11 ₃ formed inside the engine block 11 It flows into the first main exhaust passage e ₁ formed in and flows from there into the main exhaust expansion chamber e ₃ formed so as to be sandwiched between the exhaust passage member 48 and the oil case 41 through the communication port e ₂ . Exhaust gas in the main exhaust expansion chamber e ₃ flows into the second main exhaust passage e ₅ formed in the oil case 41 through the communication port e _4, and is discharged therefrom into the exhaust expansion chamber 49 of the extension case 42 .

Exhaust expansion chamber of extension case 42
Sub exhaust passage e extending upward from ₁₁Is the second main exhaust
Passage e_FiveIs formed parallel to the left side of the
Road e ₁₁Is the communication hole e₁₂Through the exhaust passage forming member 48 and
Sub exhaust expansion chamber e formed between the oil and oil case 41₁₃
Communicate with First auxiliary exhaust expansion chamber e₁₃Is the oil case 4
1 and the throttle effect formed between the exhaust passage forming member 48
Narrow part e₁₄Through the oil case 41 and the exhaust
The second auxiliary exhaust expansion chamber e formed between the passage forming members 48_FifteenTo
The second auxiliary exhaust expansion chamber e_FifteenIs an exhaust passage forming member
48, an exhaust outlet e provided on the rear surface₈Communicate with And the second
2 auxiliary exhaust expansion chamber e_FifteenIs the drain hole e ₉Through the second
Main exhaust passage e_FiveTo the exhaust passage forming member 48
Negative pressure release hole e formed_TenThrough the main exhaust expansion chamber e_ThreeAnd
And the first auxiliary exhaust expansion chamber e₁₃Communicate.

According to the second embodiment, the same operation and effect as those of the first embodiment can be achieved. In particular, the inside of the exhaust passage member 48 is provided with the first auxiliary exhaust expansion chamber e ₁₃ and the second auxiliary exhaust expansion chamber e ₁₅ across the narrow portion e ₁₄ having a throttling effect, an exhaust silencing effect Can be further enhanced.

Although the embodiments of the present invention have been described above, various design changes can be made in the present invention without departing from the gist thereof.

[0031]

As described above, according to the first aspect of the present invention, the exhaust silence is provided between the lid and the case which are detachably connected to cover the opening of the side wall of the case. Since the exhaust passage constituting the portion is formed, the degree of freedom in designing the exhaust silencer can be increased and the exhaust silence effect can be enhanced as compared with the case where the exhaust silencer is formed inside the case body.
Moreover, it is possible to perform maintenance by exposing the exhaust passage only by separating the lid from the case body without disassembling the case body, thereby greatly improving the maintainability.

According to the second aspect of the present invention,
Even when the oil pan for storing the engine's lubricating oil is integrally formed inside the case body, maintenance of the exhaust passage can be performed simply by separating the lid body from the case body without being obstructed by the oil pan. In addition, the interference between the oil pan and the exhaust silencer can be avoided to ensure a sufficient volume for both.

[Brief description of the drawings]

FIG. 1 is an overall side view of an outboard motor.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is an enlarged view taken along line 4-4 of FIG. 1;

FIG. 5 is an enlarged view of a main part of FIG. 2;

FIG. 6 is a view taken along line 6-6 of FIG. 5;

FIG. 7 is a view taken along line 7-7 in FIG. 5;

FIG. 8 is a view corresponding to FIG. 5 according to a second embodiment of the present invention.

9 is a view taken in the direction of arrows 9-9 in FIG. 8;

FIG. 10 is a view taken on line 10-10 of FIG. 8;

[Explanation of symbols]

41 oil case (case body) 41 ₁ oil pan 48 exhaust passage forming member (lid) 50 drive shaft 52 propeller E engine e ₂ communication port (opening) e ₄ communication port (opening)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideaki Takada 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G004 AA05 BA01 BA09 CA04 DA01 3G015 AA01 AA03 AB01 BB00

Claims (2)

[Claims] The driving force of an engine (E) is controlled by a propeller (5).
Case body (4) housing drive shaft (50) to be transmitted to 2)
In the exhaust passage structure for an outboard motor in which at least a part of the exhaust passage is integrally formed in 1), openings (e ₂ , e ₄ ) of the exhaust passage are formed on a side wall of a case body (41); part (e _2, e ₄₎ a ship, characterized in that the formation of the exhaust passage for an exhaust muffler portion between the lid (48) the case body (41) which is detachably coupled to the cover Exhaust passage structure of external unit. 2. The outboard motor according to claim 1, wherein an oil pan (41 ₁ ) for storing the lubricating oil of the engine (E) is integrally formed inside the case body (41). Exhaust passage structure.