JPS6332328Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention relates to an outboard motor. Specifically, the invention is a boat that discharges engine exhaust gas into the water during high-speed operation, and discharges the engine exhaust gas into the atmosphere during low-speed operation. Regarding the external engine.

FIG. 1 shows a conventional outboard motor.

During high-speed operation, this outboard motor directs exhaust gas from the engine 1 to the lower end opening 2 of the exhaust tube 2.
a. Expansion chamber 3 of drive shaft housing 3
a. Exhaust gas from the engine 1 is discharged into the water via the unillustrated exhaust passage of the gear case 4 and the propeller boss 5, and during low-speed operation, the exhaust gas from the engine 1 is discharged through the hole 6 formed in the upper side wall 2b of the exhaust tube 2 and the drive shaft housing 3. The gas is discharged into the atmosphere through an exhaust hole 7 formed in the upper rear wall. In addition, this outboard motor cools the engine by taking in cooling water from a cooling water intake port 4a formed in the gear case 4, and then flows the cooling water through the expansion chamber 3a of the drive shaft housing 3, the exhaust passage of the gear case 4, and the exhaust passage of the gear case 4. He is trying to discharge it into the water via the propeller boss 5. In FIG. 1, 1a is a cylinder block of the engine 1, 8 is a drive shaft, and 9 is an engine holder.

Incidentally, in the above-mentioned outboard motor, although the exhaust noise generated from the engine 1 is reduced within the expansion chamber 3a of the drive shaft housing 3, a sufficient effect is not necessarily obtained.

This invention was made in view of the above circumstances.
An object of the present invention is to provide an outboard motor that can sufficiently reduce exhaust noise with a simple structure.

In order to achieve the above object, the present invention forms a resonance chamber in the drive shaft housing that communicates with the engine holder exhaust passage during low-speed operation.

Hereinafter, the outboard motor according to the present invention will be described in detail with reference to the accompanying drawings.

2 and 3 show an embodiment of an outboard motor according to the present invention.

Note that in FIGS. 2 and 3, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In the outboard motor of this embodiment, a partition wall 10 is formed at the rear of the exhaust tube 2 across the upper portions of both side walls 3b of the drive shaft housing 3. On the other hand, in the engine holder 9,
The recess 11 opening downward is the exhaust passage 9.
It is formed around a. One end 11a of this recess 11 is narrowed by a wall 12 having a hole 12a and opens at the rear of the outboard motor. Further, a cooling water downward passage 13 is formed in the engine holder 9 between the exhaust passage 9a and the recess 11.

In the outboard motor of this embodiment, the engine holder 9
By installing the exhaust tube 2 and the drive shaft housing 3 through the gasket 14, the recess 11 and the gasket 14 are
An engine holder side exhaust passage 15 is formed between them. Further, by installing the engine 1 in the engine holder 9 via the gasket 16, a resonance chamber 17 is formed between the engine 1 and the engine holder 9. Note that 17a is a hole that communicates the resonance chamber 17 with the exhaust passage 15, and 18 is a drainage passage for discharging a portion of the cooling water into the atmosphere.

Next, the operation of this embodiment will be explained, and the configuration of this embodiment will be further clarified.

Now, when the outboard motor is operating at low speed, water enters the drive shaft housing 3, causing damage to the lower end opening 2a of the exhaust tube 2 (only shown in FIG. 1) and the partition wall 10. The lower end portion 10a is submerged in water.

Therefore, the water surface 19 defines the drive shaft housing 3 into two chambers, one of which has a gasket, the rear wall 3c of the drive shaft housing 3, the bulkhead 10, and the water surface 19. , a resonance chamber 20 communicating with the exhaust passage 15 through the holes 12a, 12a of the wall 12 is formed, and on the other hand, a front wall 3b' of the exhaust passage 3a of the drive shaft housing 3, the partition wall 10, and a gasket are formed. 14 and the water surface 18 form an expansion chamber 21.

Therefore, the exhaust gas from the engine 1 is transferred to the exhaust passage 9.
a, the exhaust tube 2 is discharged into the atmosphere through the plurality of holes 2c, the expansion chamber 17, the exhaust passage 15, and the passage 11a. At this time, the exhaust sound of the exhaust gas is reduced by the resonance chamber 16, and
reduced by the resonance chamber 17.

As described above, in the outboard motor according to the present invention, a resonance chamber is formed in the exhaust passage on the engine holder side during low-speed operation, so that exhaust noise can be sufficiently attenuated with a simple structure.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of a conventional outboard motor, and Figs. 2 and 3 show an embodiment of the outboard motor according to the present invention. The cross-sectional side view and FIG. 3 are bottom views of the engine holder. 1...Engine, 3...Driveshaft housing, 3b...Side wall, 3c...Rear wall, 9...
Engine holder, 10... bulkhead, 11... recess,
14...Gasket, 15...Engine holder side exhaust passage, 19...Water surface, 20...Resonance chamber.

Claims (1)

[Scope of utility model registration request] In outboard motors that discharge engine exhaust gas into the water during high-speed operation and into the atmosphere during low-speed operation, a recess that opens downward is formed in the engine holder, and a recess that opens downward is formed in the engine holder. By forming a partition across both side walls of the shaft housing and installing the drive shaft housing on the engine holder via a gasket, an engine holder side exhaust passage is formed by the recess and the gasket. , a resonance chamber communicating with the engine holder exhaust passage is formed by the gasket, the rear wall of the drive shaft housing, the partition wall, and a surface of water that enters the drive shaft housing during low-speed operation. An outboard motor characterized by the following features: