JPH0240016A - Exhaust device of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce noises emitted from an outer tube in an exhaust device of an internal combustion engine constituted of a double-tube structure having outer and inner tubular sections by supporting the inner tubular section with an elastic member. CONSTITUTION:The vibration of a tubular body 22 vibrated by exhaust pressure waves is attenuated by mount rubbers 44, 45 be restrained from vibrating a casing 14 through a water wall and an air layer to provide sounds. Also, the vibration of the tubular body 22 vibrated by the exhaust pressure wave is vibrationally insulated by mount rubbers 44, 45 to be restrained from being transmitted to the casing 14 through an intermediate member 15 and vibrating the casing 14 to provide sounds. Also, the tubular body 22 and mount rubbers 44, 45 absorb the vibration to reduce the vibration of the casing caused by the vibration of an engine and restrain said vibration 14 from providing sounds. As a result, when a portion of an exhaust path is constructed of double tubes, noises emitted from the casing 14 can be reduced.

Description

[Detailed description of the invention] “Industrial Application Fields” The present invention relates to an exhaust system for an internal combustion engine.

[Prior Art] In conventional exhaust systems for outboard motors, etc., at least a portion of the exhaust passage is divided into an outer cylindrical portion (for example, a casing) and an inner cylindrical portion (for example, a casing).
For example, some have a double-tube structure consisting of a wall forming an exhaust expansion chamber. At this time, the inner cylindrical portion is directly fixed to an intermediate member or the like that is integrated with the engine and the outer cylindrical portion with bolts or the like, and is supported in a cantilevered manner.

Note that the reason for the double cylinder structure is due to various requests such as providing an ice wall, an exhaust passage, or a sound deadening layer between the outer cylinder part and the inner cylinder part.6 [Problems to be Solved by the Invention] However, 4 2. In the conventional exhaust system, the following noises are radiated from the outer cylinder to the surroundings.

■Vibrations in the inner cylinder caused by internal exhaust pressure waves are transmitted to the outer cylinder through ice walls, air layers, etc., which excites the outer cylinder and produces noise.

(2) Vibrations in the inner tube caused by internal exhaust pressure waves are transmitted to the outer tube via intermediate members, etc., which excites the outer tube and produces noise.

■The vibrations of the engine are transmitted to the outer cylinder via intermediate members, etc.
This vibrates the outer cylinder part and produces noise.

An object of the present invention is to reduce noise radiated from the outer cylinder when at least a portion of the exhaust path has a double cylinder structure.

[Means for Solving the Problems] The present invention includes an exhaust path connected to the exhaust port of the engine, and at least a part of the loss path is configured with a double cylinder structure consisting of an outer cylinder part and an inner cylinder part. In the internal combustion engine air loss device,
The inner cylinder portion is supported by an elastic member.

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

Regarding (2) above, the vibration of the inner cylinder excited by internal exhaust pressure waves is attenuated by the first elastic member, and this can cause the outer cylinder to vibrate through ice walls, air layers, etc., resulting in sound. suppressed.

Regarding (2) above, the vibration of the inner cylinder excited by the internal exhaust pressure wave is insulated by the elastic member, and is transmitted to the outer cylinder through the intermediate member etc., causing the outer cylinder to vibrate. This suppresses the occurrence of noise.

Concerning the above-mentioned point (2), the inner cylinder part and the elastic member act like a dynamic vibration absorber to reduce the vibrations of the outer cylinder part caused by engine vibrations, thereby suppressing the vibrations from becoming noise.

As a result of the above, when at least a portion of the air-loss path has a double-tube structure, the radiated noise from the outer cylinder can be reduced.

[Embodiment] Fig. 1 is a sectional view of a main part showing a first embodiment of the present invention, Fig. 2 is a sectional view taken along line II-II in Fig. 1, and Fig. 3 is a sectional view taken along line II-II in Fig. 1. A cross-sectional view along the line, Figure 4 is IV-IV of Figure 2.
A cross-sectional view along the line, FIG. 5, is a schematic diagram of the exhaust path in FIG. 1.

As shown in FIG.
The propulsion unit 12 can be attached to the stern plate 13 via. The propulsion unit 17 has an engine 16 mounted on the negative side of the casing 14 via an intermediate member 15. The output of the engine 16 is transmitted to the propeller shaft 18 via the drive shaft 17, allowing the propeller 19 to be driven. The engine 16 is a water-cooled engine, and the water pump 20 driven by the drive shaft 17 is connected to the outside water intake port 2.
The outside water taken in from 1 is pumped to the engine 16.

The casing 14 holds a cylinder 22 in its center. The cylindrical body 22 forms a main W tension chamber 23 inside thereof. The main expansion chamber 23 is provided with an exhaust pipe 26 that communicates with an air loss passage 24 of the engine 16 and an exhaust passage 25 of the intermediate member 15.
is open.

That is, in this embodiment, a part of the exhaust path connected to the engine 16 is configured with a double cylinder structure consisting of the casing 14 (outer cylinder part) and the cylinder body 22 (inner cylinder part).

The main expansion chamber 23 communicates with the water outside through a wake passage 27 formed in the lower part of the casing 14 and a main exhaust port 29 formed in the boss portion 28 of the propeller 19. The exhaust passages 24, 25, the main expansion chamber 23, and the exhaust passage 27 form a main exhaust passage.

In addition, the main expansion chamber 23 includes the casing 14 and the intermediate member 15.
, a sub-exhaust passage 30 formed in the cylindrical body 22 and a casing 1
It communicates with the outside water or the air through the sub-capture air 31 formed at the rear of the tank 4.

Here, the sub-exhaust port 31 is arranged at one level from the main exhaust port 29.

As shown in FIGS. 1 to 4, the sub exhaust passage 30 includes a thank-you passage 32 that opens on both sides of the cylinder 22 and communicates with the main expansion chamber 23, and a thank-you passage 32 between the casing 14 and the cylinder 22. A first sub-expansion chamber 33 formed and located downstream of the thank-you passage 32
, the first sub-expansion chamber 3 opens at both sides of the bottom of the intermediate member 15.
3, and a second sub-expansion chamber 35 formed in the intermediate member 15 and located downstream of the communication path 34.
, a communication passage 36 that opens at the rear of the intermediate member 15 and is located on the downstream side of the second auxiliary expansion chamber 35, and a third auxiliary expansion chamber 37 that is formed at the rear of the cylinder body 22 and is located on the downstream side of the communication passage 36. It is configured.

The cooling water after cooling the engine 16 is discharged from the drainage passage 41 of the engine 16 to the drainage passage 42 of the intermediate member 15, and is further discharged from the small hole 43 provided at the bottom of the intermediate member 15 and connected to the drainage passage 42. It is discharged to the first sub-expansion chamber 33. The cooling water guided to the first sub-expansion chamber 33 forms an ice wall between the casing 14 and the cylindrical body 22, and the casing 1
The water overflows from one end of the water wall forming wall 14a of No. 4, flows out to the outside from an outlet (not shown), and the milk-like passageway 32 and flows out into the main expansion chamber 23. Note that a part of the cooling water guided to the drainage passage 42 of the intermediate member 15 may be directly discharged into the main chamber 23 and dropped around the exhaust pipe 26. Note that, at low speeds, mainly the gas waste passes through the milky passage 32 from the main expansion chamber 23 toward the ice wall side in response to the exhaust pulse.

Thus, the cylindrical body 22 is supported by the mount rubber 44 (elastic member) provided at the lower end of the inner surface of the ice wall of the casing 14 at its lower end, and the metal periphery at one end of the cylindrical body 22 is It is supported by a mount comb 45 (elastic member) provided on the lower end surface. The mount rubber 44 is cooled by the water on the ice wall, and the mount rubber 45 is cooled by the water on the ice wall.
It is cooled by the water (water falling from the small hole 43 connected to the drainage passage 42) captured by the water receiving part 46 provided on the outer peripheral part of the double chain side.

FIG. 5 schematically shows the above-mentioned exhaust route.

Next, the operation of the first embodiment described in Section 2 will be explained.

According to the above embodiment, (1) In the low speed and low load operation range of the engine 16 where the exhaust pressure of the engine 16 is lower than the head pressure of external water acting on the main exhaust port 29, the exhaust gas of the engine 16 is discharged from the sub exhaust port 31; ■ In the high-speed, high-load operation range of the engine 16 where the exhaust pressure of the engine 16 is higher than the head pressure of outside water acting on the main exhaust port 29, the exhaust gas of the engine 16 enters the water from the main exhaust port 29. It is discharged.

Therefore, the vibration of the cylindrical body 22 caused by the exhaust pressure wave is
It is damped by the mount rubber 44.45, and this is the ice wall,
Vibration of the casing 14 through the air layer or the like, resulting in noise, is suppressed.

Further, the vibration of the cylinder body 22 excited by the exhaust pressure wave is insulated by the mount rubber 44, 45, and is transmitted to the casing 14 via the intermediate member 15.
4 is suppressed from causing sound.

Further, the cylinder body 22 and the mount combs 44, 45 act like a dynamic vibration absorber to reduce vibrations of the casing 14 caused by engine vibrations, thereby suppressing vibrations from becoming noise.

According to the above-42, when a part of the exhaust path has a double-tube structure, the radiated noise from the casing 14 can be reduced.

Further, in this embodiment, it is possible to prevent the vibration of the cylindrical body 22 from amplifying the internal sound and emitting it as a loud idle hall sound from the sub-exhaust port 31, and it is also possible to reduce the idle-hall sound coming from the sub-exhaust port 31. .

FIG. 6 is a cross-sectional view of a main part showing a second embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG.

Functional parts in this second embodiment that are substantially the same as those in the first embodiment are given the same reference numerals, and a description thereof will be omitted.

This second embodiment differs from the first embodiment in that the casing 14 is connected to the engine 16 without intervening an intermediate member 15.
This is because an exhaust pipe 51 is provided inside the casing 14, which is connected to the engine 16(7)4i1F and directly connected to the air passage 24.

That is, in this second embodiment, a part of the exhaust path connected to the enshiff 16 is configured with a double cylinder structure consisting of the casing 14 (outer cylinder part) and the exhaust pipe 51 (inner cylinder part).

In the outboard motor 10 , a water jacket 54 surrounding the exhaust pipe 51 is formed between the partition wall 52 provided inside the casing 14 and the outer peripheral wall 53 on the rear side, and the air pipe 51 . 55
is a drainage passage for draining overflow water of the water jacket 54.

Furthermore, the outboard motor 10 has an exhaust expansion chamber 5 located in front of the exhaust pipe 51 due to the partition wall 52 of the casing 14 and another partition wall 56 disposed in front of the partition wall 52.
7 is formed. The loss expansion chamber 57 is located in the casing 14
It communicates with the outside via an exhaust passage 58 formed in the lower side portion of the propeller and an exhaust passage formed in the propeller boss portion. Note that the casing 14 has an exhaust communication passage 59 open in the upper portion of the partition wall 52. Thereby, the loss-of-air expansion chamber 57 communicates with the two-part space of the water jacket 54 via the exhaust communication path 59, and further communicates with the outside via the idle hole 60 provided in the outer peripheral wall 53 on the rear side of the casing 14. is connected to. That is, in the low speed and low load operating range of the engine 16, U1 air flows into the exhaust expansion chamber 57.
, exhaust communication passage 59. The water is discharged from the idle hole 60 through the upper space of the water jacket I-54. On the other hand, in a high-speed, high-load operating range of the engine 16, exhaust gas is discharged from the propeller boss through the exhaust expansion chamber 57 and the exhaust passage 58.

Therefore, in this second embodiment, the exhaust pipe 51 is
The entire circumference of its lower end is supported by a mount rubber 61 (elastic member) provided inside the casing 14, and the entire circumference of its upper end is supported by a mount rubber 62 provided on the lower end surface of the engine 16.
(elastic member).

Therefore, in this case as well, the vibration of the exhaust pipe 51 is caused by the mount rubber 61.on the same principle as in the first embodiment.
62 for damping or vibration isolation. Also,
The exhaust pipe 51 and the mount rubbers 61 and 62 act as a dynamic vibration absorber. Thereby, the radiated noise from the casing 14 can be reduced.

Further, it is also possible to prevent the vibration of the exhaust pipe 51 from amplifying the internal sound and emitting it from the idle hole 60 as a loud idle hole sound.

FIG. 8 is a schematic diagram showing a third embodiment of the present invention.

This third embodiment is an example of application to a 7° inboard engine of a water jet propulsion boat or the like. In the figure, 71 is the hull, 72 is the engine,
73 is a water injection passage, and 74 is an impeller. engine 7
A part of the exhaust path 75 connected to the exhaust expansion case 76
It has a double cylinder structure consisting of (outer cylinder part) and exhaust pipe 77 (inner cylinder part). Furthermore, the front and rear ends of the exhaust pipe 77 are supported by mount rubbers 78 and 79 (elastic members). Also in this case, the radiated noise from the exhaust expansion case 76 can be reduced.

FIG. 9 is a schematic diagram showing a fourth embodiment of the present invention.

This fourth embodiment is an example of application to a motorcycle 80. An inner cylinder 83 (inner cylinder part) is provided inside an exhaust pipe 82 (outer cylinder part) connected to the engine 81, resulting in a double cylinder structure. Furthermore, the front and rear ends of the inner cylinder 83 are attached to the mount rubber 84.85.
(elastic member). In this case as well, the exhaust pipe 8
The radiated noise from 2 can be reduced.

[Effects of the Invention] As described above, according to the present invention, when at least a portion of the exhaust path has a double-tube structure, the radiated noise from the outer cylinder can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG.
A cross-sectional view taken along line mm in the figure, Figure 4 is ff-T in Figure 2.
5 is a schematic diagram of the exhaust route in FIG. 1; FIG. 6 is a sectional view of main parts showing a second embodiment of the present invention;
FIG. 7 is a sectional view taken along the line ■-■ in FIG. 6, FIG. 8 is a schematic diagram showing a third embodiment of the present invention, and FIG. 9 is a schematic diagram showing a fourth embodiment of the present invention. . 14...Casing (outer cylinder part), 16...Engine, 22...Cylinder body (inner cylinder part), 44.45...Mount rubber (elastic member), 51...
・Exhaust pipe (inner cylinder part), 61.62...Mount rubber (elastic member), 72...
・Engine, 76...Exhaust expansion case (outer cylinder part), 77...Exhaust pipe (inner cylinder part), 78.79...Mount rubber (elastic member) 81...
Engine, 82...Exhaust pipe (outer cylinder part), 83...Inner cylinder (inner cylinder part), 84.85...Mount rubber (elastic member). Agent Patent Attorney Osamu Shiokawa

Claims (1)

[Claims] (1) In an exhaust system for an internal combustion engine, which includes an exhaust path connected to an exhaust port of the engine, and in which at least a portion of the exhaust path is configured with a double cylinder structure consisting of an outer cylinder part and an inner cylinder part, the inner cylinder An exhaust system for an internal combustion engine, characterized in that a portion of the exhaust system is supported by an elastic member.