JPH1018841A - Exhaust structure for outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust structure for an outboard engine in which exhaust noise can be reduced at a low cost and a quality of the exhaust noise can be improved. SOLUTION: In an outboard engine 1 in which a power unit 4 including an engine 6 is mounted on an upper case 3, an exhaust pipe 24 introducing out of the engine 6 is made of a pipe material (SUS pipe), which is bent outside of the engine 6 to extend vertically downward along the upper case 3 and is opened at the lower end thereof to water. Consequently, since exhaust gas discharged from the engine 6 is discharged to the water through the exhaust pipe 24, which is simply constituted by bending the pipe material, exhaust noise can be reduced at a low cost and a quality of the exhaust noise can be improved, thus eliminating an unpleasant feeling of crews.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exhaust structure of an outboard motor in which a power unit including an engine is mounted on an upper case.

[0002]

2. Description of the Related Art In an outboard motor that is simply constructed by mounting a power unit including an engine on an upper case, exhaust gas emitted from the engine is directly discharged to the atmosphere.

[0003]

However, if the exhaust gas from the engine is discharged into the atmosphere as it is in the conventional simple outboard motor, the exhaust noise becomes large and the sound quality also makes the passenger uncomfortable. It was.

Therefore, it is conceivable that an exhaust passage is formed in the main body of the outboard motor and exhaust gas is discharged into the water through the exhaust passage. It is not possible to form an exhaust passage inside in terms of cost.

The present invention has been made in view of the above problems, and an object thereof is to provide an exhaust structure of an outboard motor capable of reducing exhaust noise at low cost and improving the sound quality of exhaust. Is to do.

[0006]

According to one aspect of the present invention, there is provided an outboard motor in which a power unit including an engine is mounted on an upper case. It is characterized by comprising a pipe material, bending the pipe material outside the engine, extending vertically downward along the upper case, and opening its lower end into water.

According to a second aspect of the present invention, in the first aspect of the present invention, an idle hole which is always open to the atmosphere is provided in the exhaust pipe.

Furthermore, the invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the pipe material is an SUS pipe.

Therefore, according to the first aspect of the present invention, since the exhaust gas discharged from the engine is discharged into the water through the exhaust pipe which is formed by bending the pipe material,
Exhaust noise is reduced at low cost, and the sound quality of the exhaust is also improved, thereby eliminating discomfort to the occupants.

According to the second aspect of the invention, during idling when the engine speed is low and the exhaust gas amount and exhaust gas pressure are small, the exhaust gas is exhausted from the idle hole that is always open to the atmosphere without resistance. However, since the exhaust noise is originally low at the time of idling, there is no problem even if exhaust gas is discharged into the atmosphere.

Further, according to the third aspect of the invention, since the exhaust pipe is made of a SUS pipe, it is possible to secure high corrosion resistance in the exhaust pipe.

[0012]

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

FIG. 1 is a left side view of an outboard motor having an exhaust structure according to the present invention, FIG. 2 is an enlarged sectional view of a portion A in FIG. 1, and FIG. 3 is a side sectional view of a power unit portion of the outboard motor. 4 is a plan view of the outboard motor.

As shown in FIG. 1, an outboard motor 1 according to the present embodiment is attached to a rear portion of a hull 50 by a clamp bracket 2, and a power unit 4 is mounted on an upper portion of an upper case 3. The lower case 5 is attached to the lower part of the upper case 3.

The power unit 4 includes an air-cooled four-cycle single-cylinder engine 6.
Are arranged in a vertical direction. As shown in detail in FIG. 3, the cylinder body 8 of the engine 6 is arranged horizontally with the cylinder bore axis facing the hull longitudinal direction (vertical direction in FIG. 3). A crankcase 9 is attached, and a cylinder head 10 is attached to a front mating surface of the cylinder body 8.

A piston 11 is horizontally slidably fitted in the cylinder bore 8a of the cylinder body 8, and the piston 11 is connected to the crankshaft 7 via a connecting rod 12.

A flywheel 13 and a recoil starter 14 are connected to an upper end of the crankshaft 7, and a lower end of the crankshaft 7 is connected to an upper end of a drive shaft 16 by a coupling 15. (See FIG. 1). A fuel tank 18 is provided on a cover 17 that covers an upper portion of the engine 6, and an engine hanger 19 is attached to a rear surface of the crankcase 9.

On the other hand, an intake passage 20 and an exhaust passage 21 are formed in the cylinder head 10, and these are opened and closed at appropriate timing by an intake valve 22 and an exhaust valve 23, respectively.

One end of an exhaust pipe 24 is attached to the exhaust passage 21 opened on the upper surface of the cylinder head 10 by a bolt 26 via a flange 25. The exhaust pipe 24 is formed by bending an SUS pipe, which rises upward from the cylinder head 10 and then extends substantially horizontally in the cover 17 to the left (downward in FIG. 4).
1 and 3, extend vertically downward as shown in FIGS. 1 and 3, then diagonally downward toward the rear, and extend substantially horizontally rearward below the engine 6. As shown in FIG. 4, it is bent at a substantially right angle and extends horizontally toward the center of the engine 6 in the width direction, and is bent vertically downward at the center of the engine 6 in the width direction and extends vertically downward along the upper case 3 and its lower end. The portion is bent rearward in a U-shape and opens into the water above the lower case 5. As shown in FIG. 1, the lower end of the exhaust pipe 24 is fixed to the upper case 3 by a bracket 25 to prevent the exhaust pipe 24 from being damaged by the vibration of the bent portion. In this case, if the bracket 25 is attached via a vibration isolator, the vibration of the exhaust pipe 24 can be suppressed small.

As shown in FIG. 2, an idle hole 26 is opened in the front surface of the exhaust pipe 24 at an intermediate height extending vertically downward along the upper case 2 and is connected to the idle hole 26. The small diameter pipe 27 is shown in FIG.
As shown in FIG. 5, after extending forward, it is folded downward and extends downward along the exhaust pipe 24, and its lower end is always open to the atmosphere above the lower end opening of the exhaust pipe 24. .

The upper case 3 is shown in FIG.
As shown in the figure, the upper case 3a and the lower case 3b integrally cast from an aluminum alloy are welded with an aluminum alloy pipe 3c. The support bracket 28 is supported by the clamp bracket 2 by a tilt shaft 29 so as to be vertically rotatable. Therefore, the outboard motor 1 is swingable up and down around the tilt shaft 29 and is supported so as to be able to turn left and right around the pipe 3c of the upper case 3.
In the present embodiment, since the upper case 3 has the welding structure as described above, the number of manufacturing coils can be reduced as compared with the case where the upper case 3 is manufactured by integral casting.

In the present embodiment, the power unit 4 has four mount rubbers (anti-vibration rubber) 3.
The steering wheel 31 is attached to the upper case 3a while being elastically supported on the upper case 3a through the upper case 3 via the upper case 3a. A weight 32 having an appropriate size and weight is attached to the end face of the cylinder head 10 of the engine 6.

Here, the mounting structure of the power unit 4 will be described with reference to FIGS.

As shown in FIG. 4, the four mount rubbers 30 elastically supporting the power unit 4 with respect to the upper case 3 are arranged at an equal angular pitch (90 ° pitch) on the same circumference. As shown in FIG. 3, a bolt 33 inserted from below into a flange portion 3a-1 formed on an upper case 3a of an upper case 3 is inserted through the mount rubber 30, and this is screwed into a crankcase cover 34. Attached by wearing.

On the other hand, as shown in FIG. 1, the steering handle 31 extends obliquely upward from the upper case 3a of the upper case 3 forward (to the left in FIG. 1).
A grip 35 is attached to the free end, and a throttle lever 36 and a shift lever 37 are provided at an intermediate portion. The throttle lever 36 is connected to the throttle wire 3
8 is connected to a throttle valve (not shown) provided in the engine 6.

Next, the configuration of the power transmission system will be described.

As shown in FIG. 1, the drive shaft 16 is vertically disposed by vertically cutting the upper case 3, and the lower end thereof is connected to a forward / reverse switching mechanism 39 housed in the lower case 5. I have. Here, the forward / reverse switching mechanism 39 switches the rotation of the drive shaft 16 and switches this rotation to the propeller shaft 4.
A propeller 41 is attached to a rear end of the propeller shaft 40 which extends outside the lower case 5.

The switching operation (shift operation) between forward and backward is performed by the shift lever 37 provided on the steering handle 31. That is, as shown in FIG. 1, a link plate 42 is pivotally attached to the upper case 3a of the upper case 3 so as to be freely rotatable, and the shift lever 3 provided on one end of the link plate 42 and the steering handle 31 is provided.
6 is connected by a link rod 43, and the other end of the link plate 42 is connected to the upper end of a shift rod 44. The shift rod 44 extends vertically through the upper case 3, and a shift cam 45 is attached to the lower end thereof.

When the shift lever 37 is tilted forward, the shift rod 44 moves upward and the forward gear of the forward / reverse switching mechanism 39 is moved to the propeller shaft 40 by the shift cam 45 attached to the lower end of the shift rod. When the shift lever 37 is tilted backward, the shift rod 44 is moved downward, and the reverse gear of the forward / reverse switching mechanism 39 is moved by the shift cam 45 attached to the lower end of the shift rod. It is connected to the propeller shaft 40 and is switched to the reverse state.

The pipe 3c of the upper case 3
A reverse lock mechanism 46 is provided at an intermediate height position of. The reverse lock mechanism 46 is composed of a stopper bracket 47 attached to the lower end of the crank bracket 2 and a locking member 48 attached to the shift rod 44. When the shift rod 44 moves downward, the locking member 48 connected to the shift rod 44 also moves downward and engages with the stopper bracket 47, so that the reverse lock state is established and the reaction force is generated when the vehicle is moving backward. The tilt-up swing of the outboard motor 1 is prevented. Then, when the shift rod 44 is moved upward by the forward-side switching operation by the shift operation as described above, the locking member 48 attached thereto is also moved upward integrally, and the engagement with the stopper bracket 47 is released. Therefore, the reverse lock state is also released.

When the engine 6 of the power unit 4 is driven in the outboard motor 1, the rotation of the crankshaft 7 of the engine 6 is controlled by the drive shaft 16 and the forward / reverse switching mechanism 3.
9 and transmitted to the propeller shaft 40, the propeller shaft 40
In addition, the propeller 41 connected thereto is rotationally driven to generate a required propulsion force.

The exhaust gas discharged from the engine 6 flows through the exhaust pipe 24 formed by bending the SUS pipe, and is discharged into the water from the lower end opening of the exhaust pipe 24 submerged in the water. Exhaust noise is reduced at low cost, and the sound quality of the exhaust is also improved, thereby eliminating discomfort to the occupants. In addition, as a result of actually measuring the exhaust noise in the outboard motor 1 according to the present embodiment, it was possible to reduce the exhaust noise by about 1 dB as compared with a conventional outboard motor that discharges exhaust gas into the atmosphere.

When the engine 6 is idling at a low rotational speed and a low exhaust gas amount and exhaust gas pressure,
Exhaust gas is discharged from the idle hole 26, which always opens into the atmosphere, through the small-diameter pipe 27 into the atmosphere without any resistance. However, since exhaust noise is originally low during idling, there is no problem if the exhaust gas is discharged into the atmosphere. Does not occur.

In this embodiment, the exhaust pipe 24 is S
Since the exhaust pipe 24 is formed of a US pipe, high corrosion resistance is secured.

Although the exhaust structure of an outboard motor equipped with a four-cycle single cylinder engine has been particularly described above, the present invention is similarly applied to the exhaust structure of an outboard motor equipped with a multi-cylinder engine. Of course, you can do that.

[0036]

As is apparent from the above description, according to the present invention, in an outboard motor in which a power unit including an engine is mounted on an upper case, an exhaust pipe led out from the engine is formed of a pipe material. Then, the pipe material is bent outside the engine and extended vertically downward along the upper case, and the lower end thereof is opened in water, so that it is possible to reduce exhaust noise at low cost, The effect is obtained that the sound quality of the exhaust gas can be improved.

[Brief description of the drawings]

FIG. 1 is a left side view of an outboard motor provided with an exhaust structure according to the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is a side sectional view of a power unit portion of an outboard motor having an exhaust structure according to the present invention.

FIG. 4 is a plan view of an outboard motor including the exhaust structure according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 3 Upper case 4 Power unit 6 Engine 24 Exhaust pipe 26 Idle hall

Claims (3)

[Claims] 1. An outboard motor comprising a power unit including an engine mounted on an upper case, wherein an exhaust pipe derived from the engine is formed of a pipe material,
An exhaust structure for an outboard motor, wherein the pipe member is bent outside the engine and extends vertically downward along the upper case, and a lower end thereof is opened in water. 2. The exhaust structure for an outboard motor according to claim 1, wherein an idle hole that is always open to the atmosphere is opened in the middle of the exhaust pipe. 3. The exhaust structure for an outboard motor according to claim 1, wherein the pipe member is a SUS pipe.