JP3484924B2 - Exhaust release structure of outboard motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] The present invention relates to an exhaust release structure for an outboard motor. 2. Description of the Related Art In an outboard motor, when the engine is started and idling, the exhaust pressure of the engine is small. Emission is also difficult. Therefore, an exhaust release passage communicating with the atmosphere is provided in the exhaust passage,
Part of the exhaust gas is released into the atmosphere. When exhaust gas is directly discharged from the exhaust passage, the exhaust noise becomes loud. For this reason, an exhaust release passage having a complicated maze structure is provided in the engine cover as shown in Japanese Utility Model Publication No. 64-2700, for example. Kaihei 5-92
No. 797, it is provided inside a drive shaft housing. [0004] However, in any of the conventional examples, since a dedicated part is separately provided for forming an exhaust release passage having a maze structure, the structure becomes complicated, and the weight and cost are reduced. Will increase. The present invention has been made in view of the above circumstances, and has as its object to provide an outboard motor exhaust release structure which has a simple structure and reduces weight and cost. According to a first aspect of the present invention, there is provided an exhaust release structure for an outboard motor according to the present invention. the in outboard motor to discharge the water after that led to the exhaust expansion chamber in the drive shaft housing, between said engine and said drive shaft housing, the ene
Engine holder and drive above located at the bottom of the gin
The oil pan located at the top of the shaft housing
A plurality of intermediate members provided are provided, and an exhaust release passage is provided integrally with the intermediate members to allow the inside of the drive shaft housing and the atmosphere to communicate with each other, and a throttle hole is formed in a gasket disposed between the intermediate members. , The intermediate part
The exhaust release passage provided in the material is composed of an ascending chamber section and a descending chamber section, and these ascending chamber section and
The lowering chamber and the left and right rear parts of the intermediate member in plan view
They are juxtaposed . According to another aspect of the present invention, there is provided a cam chain case in which the intermediate member is disposed at a lower portion of the engine, an engine holder disposed at a lower portion of the cam chain case. And an oil pan disposed above the drive shaft housing. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a left vertical sectional view of an outboard motor to which the present invention is applied, and FIG. 2 is a rear view thereof. As shown in FIGS. 1 and 2, the outboard motor 1 includes an engine holder 2 as an intermediate member, and an engine 3 is installed above the engine holder 2. The engine 3 is, for example, a water-cooled four-cycle three-cylinder engine,
It is configured by combining a cylinder block 5 and a crankcase 6 and the like, and is mounted on the engine holder 2 via a cam chain case 7 which is another intermediate member. The cylinder block 5 is arranged behind the crankcase 6, that is, on the right side in FIG. The cylinder head 4 is disposed behind the cylinder block 5. The cam chain case 7 is arranged below the crankcase 6, the cylinder block 5, and the cylinder head 4. A crankshaft 8 is disposed vertically in the crankcase 6, and an oil pan 9, which is another intermediate member, is disposed below the engine holder 2. In addition, the periphery from the engine 3 to the oil pan 9 is covered with an engine cover 10. A drive shaft housing 11 is provided below the oil pan 9. The upper end of the drive shaft 12 is fitted, for example, by spline fitting to the lower end of the crankshaft 8. The drive shaft 12 extends downward in a shaft pipe 13 formed in the drive shaft housing 11, and a gear case 14 provided in a lower portion of the drive shaft housing 11.
It is configured to drive the propeller 15 via a bevel gear and a propeller shaft (not shown). FIG. 3 is a sectional view taken along the line III-III in FIG. As shown in FIGS. 1 and 3, a combustion chamber 17 is formed in the cylinder head 4 of the engine 3 so as to match a cylinder 16 formed horizontally in the cylinder block 5, and a spark plug 18 is connected from the outside thereof. Is done. A piston 19 is slidably inserted in the cylinder 16 in the horizontal direction, and the piston 19 and the crankshaft 8 are connected by a connecting rod 20. Then, the reciprocating stroke of the piston 19 is converted into the rotational movement of the crankshaft 8. In the cylinder head 4, an intake port 21 and an exhaust port 22 connected to the combustion chamber 17 are formed. Further, an intake valve 23 and an exhaust valve 24 for opening and closing both ports 21 and 22 are arranged in the cylinder head 4.
Furthermore, these valves 2 are provided at the rear of the cylinder head 4.
A camshaft 25 that opens and closes 3, 24 is also provided.
A cam chain (not shown) is disposed in the cam chain case 7, and the cam chain 25 operatively connects the cam shaft 25 and the crank shaft 8. The rear of the cylinder head 4 is the cylinder head cover 2
6 covered. FIG. 4 is a right side view of the outboard motor 1. FIG.
As shown in FIG. 4 and around the engine 3, an electric component box 28 in which an electric component 27 is provided, an intake device 29,
An exhaust device 30 and the like are arranged. The intake device 29 is arranged on one side of the engine 3, and the electrical component box 28 and the exhaust device 30 are arranged on the opposite side of the intake device 29. An exhaust manifold 31 constituting the exhaust device 30 is connected to the exhaust port 22, and the exhaust manifold 31 extends downward. A water jacket 32 is provided around the exhaust manifold 31.
Is formed. FIG. 5 is a plan view of the cam chain case 7, and FIG. 6 is a bottom view of the cam chain case 7. FIG. 7 is a sectional view taken along the line VII-VII in FIG. FIG. 8 is a plan view of the engine holder 2 and FIG.
Is a bottom view of the engine holder 2. FIG. FIG. 10 is a sectional view taken along line XX of FIG. Furthermore, FIG.
Is a plan view of the oil pan 9, and FIG. 12 is a bottom view of the oil pan 9. FIG. 13 shows XIII-XIII in FIG.
It is sectional drawing which follows a line. 14A is a plan view of the gasket 33 sandwiched between the cam chain case 7 and the engine holder 2, and FIG. 14B is a plan view of the gasket 33 sandwiched between the engine holder 2 and the oil pan 9. FIG. 2 is a plan view of a gasket 34 to be used. Finally, FIG. 15 is a sectional view taken along line AA of FIG. As shown in FIGS. 5 to 15, exhaust passages 2a, 7a and 9a are formed in the engine holder 2, the cam chain case 7 and the oil pan 9, respectively, so as to penetrate in the vertical direction. Exhaust passage 7a of cam chain case 7
A connection portion 7b is formed at an upper end, and a lower end portion of the exhaust manifold 31 is connected to the connection portion 7b. Also,
The lower end of the exhaust passage 9 a of the oil pan 9 opens toward an exhaust expansion chamber 35 formed in the drive shaft housing 11. These exhaust passages 2a, 7
A water jacket 36 is formed around a and 9a. Exhaust gas discharged from the engine 3 is guided from an exhaust port 22 to an exhaust expansion chamber 35 in the drive shaft housing 11 through an exhaust manifold 31 and exhaust passages 2a, 7a, 9a, for example, a propeller shaft (not shown). ) Is discharged into the water through a main exhaust port 37 formed around. The outboard motor 1 cannot discharge, for example, seawater that has entered the exhaust expansion chamber 35 into the water because the exhaust pressure of the engine 3 is low when the engine 3 is started and when the engine 3 is idling. Emission of exhaust gas also becomes difficult. Therefore, an exhaust release passage communicating with the atmosphere is provided in the middle of the exhaust passage and the like, and a part of the exhaust gas is released into the atmosphere. As shown in FIGS. 5 to 15, the exhaust release passage 38 according to the present invention is formed integrally with the engine holder 2, the cam chain case 7, and the oil pan 9 as intermediate members. The exhaust release passage 38 is composed of ascending chambers 2b, 9b provided in the engine holder 2 and the oil pan 9, and descending chambers 2c, 9c, and a connecting portion 7c provided in the cam chain case 7. , 9b and the descending chamber section 2c,
9c are arranged side by side in plan view, and the exhaust release passage 38 is arranged at the rear of each of the intermediate members 2, 7, 9. Further, as shown in FIG. 14B, a gasket 34 sandwiched between the joint surfaces of the engine holder 2 and the oil pan 9 is formed.
Is formed with a throttle hole 39. And. A release chamber 40 is formed in the drive shaft housing 11 facing the lower ends of the descending chamber portions 2c and 9c, and a sub exhaust port 41 communicating with the atmosphere is formed in the release chamber 40 (see FIGS. 1 and 15). . Next, the operation of this embodiment will be described. The exhaust gas guided from the exhaust port 22 to the exhaust expansion chamber 35 in the drive shaft housing 11 through the exhaust manifold 31 and the exhaust passages 2a, 7a, 9a at the time of starting the engine 3 or idling, for example.
Since the exhaust pressure of the engine 3 is low, for example, seawater that has entered the exhaust expansion chamber 35 cannot be discharged into the water. Therefore, as shown in FIG. 15, the exhaust gas ( arrow 42 ) enters the rising chamber 9 b of the exhaust release passage 38 formed in the oil pan 9, and then rises in the engine holder 2. It enters the chamber 2b. Since the rising chamber section 9b of the oil pan 9 is set to be narrower than the rising chamber section 2b of the engine holder 2, the exhaust gas 42 is once narrowed down by the rising chamber section 9b of the oil pan 9, and then the exhaust chamber 42 is raised. 2
Inflates at b. The exhaust gas 42 from the ascending chamber 2b of the engine holder 2 then enters the descending chamber 2c formed in the engine holder 2 via the connecting portion 7c provided in the cam chain case 7. The connecting portion 7c is set narrower than the ascending chamber portion 2b and the descending chamber portion 2c of the engine holder 2, so that the exhaust gas 42 is again narrowed down by the connecting portion 7c, and then expands again in the descending chamber portion 2c of the engine holder 2. I do. The exhaust gas 42 in the descending chamber 2c of the engine holder 2 then enters the descending chamber 9c formed in the oil pan 9. At this time, the gasket 34 sandwiched between the joining surfaces of the engine holder 2 and the oil pan 9
Is formed with the throttle hole 39, the exhaust gas 42 is again narrowed down by the throttle hole 39, and then expands again in the descending chamber portion 9c of the oil pan 9. The lowering chamber 9 of the oil pan 9
The exhaust gas 42 led to c is led to a release chamber 40 formed in the drive shaft housing 11,
The air is exhausted into the atmosphere from the sub exhaust port 41. As described above, the exhaust gas 42 is repeatedly throttled and expanded in the exhaust release passage 38, is silenced, and is discharged out of the outboard motor 1. Further, the exhaust release passage 38 is integrally formed with a plurality of intermediate members disposed between the engine 3 and the drive shaft housing 11, in this embodiment, the cam chain case 7, the engine holder 2 and the oil pan 9. Because it is formed, there is no need to provide special parts separately as in the past, and the structure is simple,
There is no increase in weight or cost. In addition, the integrally formed exhaust release passage 38 is more reliable than one formed separately. By arranging the ascending chamber portions 2b, 9b and the descending chamber portions 2c, 9c at the rear of the intermediate members 2, 7, 9 side by side in a plan view, a small space can be effectively used. This also contributes to downsizing of the entire outboard motor 1. In the above-described embodiment, the example in which the throttle hole 39 is formed only in the gasket 34 sandwiched between the joint surfaces of the engine holder 2 and the oil pan 9 has been described, but the cam chain case 7 and the engine holder A throttle hole (not shown) may be formed in the gasket 33 sandwiched between the joint surfaces with the joint 2, and the connecting portion 7c of the cam chain case 7 may also be used as an expansion chamber. Similarly, although not shown in detail, a throttle hole may be formed in the gasket between the oil pan 9 and the drive shaft housing 11. As described above, according to the exhaust release structure for an outboard motor according to the present invention, the engine holder and the oil
An exhaust release passage for communicating the inside of the drive shaft housing with the atmosphere is provided in a plurality of intermediate members of the lupine, and a throttle hole is formed in a gasket disposed between the intermediate members, and the exhaust release passage is formed in the rising chamber portion. And the lowering chamber portion, and the raising chamber portion and the lowering chamber portion are arranged side by side on the left and right of each intermediate member in a plan view, so that the entire outboard motor can be reduced in size and each intermediate member can be reduced. Tsuyoshi
It is possible to sex-up, excellent effect of the structure also reduces the weight and cost become easy and a high silencing effect and the like
To play . [0033]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a left vertical sectional view of an outboard motor showing an embodiment of an exhaust release structure for an outboard motor according to the present invention. FIG. 2 is a rear view of the outboard motor shown in FIG. FIG. 3 is a sectional view taken along the line III-III in FIG. 1; FIG. 4 is a right side view of the outboard motor shown in FIG. FIG. 5 is a plan view of a cam chain case. FIG. 6 is a bottom view of the cam chain case. FIG. 7 is a sectional view taken along the line VII-VII in FIG. 5; FIG. 8 is a plan view of the engine holder. FIG. 9 is a bottom view of the engine holder. FIG. 10 is a sectional view taken along line XX of FIG. 8; FIG. 11 is a plan view of an oil pan. FIG. 12 is a bottom view of the oil pan. FIG. 13 is a sectional view taken along the line XIII-XIII in FIG. 11; 14 (a) and (b) are plan views of a gasket sandwiched between respective intermediate members. FIG. 15 is a sectional view taken along the line AA in FIG. 1; [Description of Signs] 1 Outboard motor 2 Engine holder (intermediate member) 2a Exhaust passage of engine holder 2b Elevating chamber portion of engine holder 2c Lowering chamber portion of engine holder 3 Engine 7 Cam chain case (intermediate member) 7a Cam chain case Exhaust passage 7c Cam chain case connecting portion 9 Oil pan (intermediate member) 9a Oil pan exhaust passage 9b Oil pan rising chamber 9c Oil pan descending chamber 11 Drive shaft housing 31 Exhaust manifold 33 Gasket 34 Gasket 35 Exhaust Expansion chamber 38 exhaust release passage 39 throttle hole 41 auxiliary exhaust port 42 exhaust gas

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Katsuhiro Fukuda 300 Takatsukacho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. (72) Inventor Jun Ito 300 Takatsukacho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. (72) Inventor Akira Takahashi 300, Takatsuka-cho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. (72) Inventor Shuichi Hagino 300, Takatsuka-cho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd. (56) References , U) (58) Field surveyed (Int.Cl. ⁷ , DB name) B63H 20/24

Claims (1)

(57) [Claim 1] In an outboard motor for discharging exhaust gas discharged from an engine to an exhaust expansion chamber in a drive shaft housing and then discharging it into water, the outboard motor includes the engine and the drive shaft housing. Between the engine holder and the engine holder located below the engine
The upper part of the drive shaft housing
A plurality of intermediate members provided with an oil pan are arranged, an exhaust release passage communicating the inside of the drive shaft housing with the atmosphere is provided integrally with these intermediate members, and a throttle hole is formed in a gasket arranged between the intermediate members. The exhaust release passage provided in the intermediate member is formed by an ascending chamber section and a descending chamber section, and the ascending chamber section and the descending chamber section are juxtaposed to the rear left and right of the intermediate member in plan view . An exhaust release structure for an outboard motor.