JPS5925757Y2 - Water backflow prevention device for outboard motor exhaust pipes - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a water backflow prevention device for an exhaust pipe of an outboard motor.

An example of a conventional outboard motor is shown in FIG.

The outboard motor shown in this figure has an exhaust pipe 1 opened in a drive shaft housing (hereinafter simply referred to as housing) 2, and the exhaust gas discharged from the cylinder 3 of the engine is directed through the exhaust pipe as shown by arrow A. 1 through the housing 2 and discharged into the water from the propeller 4 part.

This type of outboard motor has a structure that allows water to enter the housing 2, and if the water level inside the housing 2 rises to W' or even if the water level is W, the water will scatter and cause damage to the exhaust pipe 1. Water often adheres to the inner peripheral surface.

In this case, if the outboard motor is tilted or placed on its side, the adhering water will flow backwards along the inner circumferential surface of the exhaust pipe 1, enter the cylinder 3, or enter the exhaust pipe 1 for exhaust purification. If a catalyst 5 is provided, there is a risk that the catalyst 5 may become wet and its catalytic function may deteriorate.

In view of the above circumstances, the purpose of this invention is to prevent backflow of water in the exhaust pipe of an outboard motor by preventing water from flowing back into the exhaust pipe during tilting, etc., flowing into the cylinder and wetting the catalyst. The purpose of the present invention is to provide a water backflow prevention device for an exhaust pipe of an outboard motor, which has an exhaust pipe connected to an engine protruding from a drive shaft housing into which water can enter. , the exhaust pipe connected to the engine is configured as a small diameter exhaust pipe, a large diameter exhaust pipe is connected to the lower part of the small diameter exhaust pipe to form a stepped part, a water drain hole is provided in the stepped part, and the small diameter exhaust pipe is connected to the lower part of the small diameter exhaust pipe. A water backflow prevention device for an exhaust pipe of an outboard motor is characterized in that the lower end of the exhaust pipe protrudes a predetermined length into the upper end of the large-diameter exhaust pipe.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

Fig. 2 is a cross-sectional conceptual diagram showing an exhaust pipe of an outboard motor equipped with a water backflow prevention device according to the present invention, and Fig. 3 is a section III-I in Fig. 2.
It is a sectional view taken along line II.

The exhaust pipe 1 shown in the figure is a small diameter exhaust pipe 6 connected to the engine.
, large diameter exhaust pipe 7 and extended exhaust pipe 8 (hereinafter simply referred to as small diameter pipe 6)
The large-diameter pipe 7 and the extension pipe 8 are connected to each other, and the pipe passes through the inside of the housing 2 and directs the exhaust gas discharged from the cylinder 3 to the propeller 4 part as shown by arrow A into the water. It is something that is discharged.

The small diameter pipe 6 is equipped with an exhaust gas purifying catalyst 5 at its upper end, and a water backflow prevention device 9 at its lower part.

This device 9 connects the upper end of the large diameter pipe 7 to the lower part of the small diameter pipe 6 to form a step 10, and the step 10 is provided with a drain hole 11, and the lower end 6a of the small diameter pipe 6 is connected to the lower end of the small diameter pipe 6 to form a step 10. It has a structure in which it protrudes a predetermined length into the upper end of the large diameter pipe 7.

FIG. 4 is a plan view showing a specific example of the water backflow prevention device 9 (
FIG. 2 is a diagram corresponding to a sectional view taken along line III-III in FIG. 2.

Figures 5 and 6 are the ■-v lines in Figure 4, VI-VI
FIG.

This backflow prevention device 9 is provided with a flange 6b at a height h from the lower outer periphery of the upper small-diameter pipe 6, that is, from the lower end, and a dish-shaped flange 7a provided at the upper end of the lower large-diameter pipe 7. Both flanges 6b and 7a are joined by bolts and nuts 12,
In addition, four semi-cylindrical ρ grooves 6C are formed radially on the flange 6b of the small diameter pipe, and the lower end 6a of the small diameter pipe is made to protrude into the upper end of the large diameter pipe 7, thereby connecting the large diameter pipe 7 and the small diameter pipe. lower end 6
It forms a gap C between it and a.

The semi-cylindrical groove 6C is the drain hole 11 explained in FIG.
corresponds to

The water backflow prevention device 9 as described above is disposed below the catalyst 5 and above the waterline of the boat when the outboard motor is attached to the boat.

By providing the water backflow prevention device 9 as described above on the exhaust pipe 1 of the outboard motor, even if water adheres to the inner circumferential surface of the exhaust pipe 1 when the outboard motor is tilted or placed on its side. The water flows along the inner peripheral surface of the exhaust pipe into the backflow prevention device 9, flows out of the exhaust pipe 1 through the drain hole 11 (groove 6C), and passes through the discharge port 8a provided at the lower end of the extension pipe 8. and leaks out of the outboard motor.

Therefore, even if the outboard motor is tilted or placed on its side, water adhering to the exhaust pipe 1 will not flow back upwards beyond the backflow prevention device 9, and there is no risk of it flowing into the cylinder 3 or wetting the catalyst 5. .

In this case, if the lower end 6a of the small diameter pipe is made to protrude into the upper end of the large diameter pipe 7, the water that has flowed into the backflow prevention device 9 can be completely flowed out of the exhaust pipe 1.

Note that the small diameter tube 6 and the large diameter tube 7 are not limited to cylindrical shapes, but may be rectangular tube shapes.

Further, the extension tube 8 is not necessarily necessary, and in some cases, the extension tube 8 may be removed and opened into the housing 2 as in the conventional example shown in FIG.

Outboard motors usually come in several types with different lengths, and the extension tube 8
was provided to accommodate this.

As explained above, if the water backflow prevention device according to the present invention is installed in the exhaust pipe of an outboard motor, water will flow back inside the drain pipe and into the cylinder even if the outboard motor is tilted or placed on its side. There is no risk of the catalyst entering the water or wetting the catalyst and causing deterioration of the catalyst function.

In addition, the water backflow prevention device according to the present invention can be easily used as an exhaust pipe and a backflow prevention device at the same time by simply processing the small diameter pipe and large diameter pipe that make up the exhaust pipe and connecting both pipes. It is very convenient because it can be configured as follows.

Furthermore, since the configuration has a small-diameter pipe placed above and a large-diameter pipe placed below, there is an advantage that even if this backflow prevention device is installed, exhaust resistance will not increase and there will be no negative impact on engine performance. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional conceptual diagram showing a conventional outboard motor, FIG. 2 is a cross-sectional conceptual diagram showing an exhaust pipe of an outboard motor according to the present invention, and FIG. 3 is a cross-sectional diagram taken along the line III--III in FIG. Figure 4 is a plan view showing the water backflow prevention device, Figures 5 and 6 are ■-V in Figure 4.
FIG. 1...Exhaust pipe, 6...Small diameter pipe, 6a.
...Lower end of small diameter pipe, 7...Large diameter pipe, 9
...Water backflow prevention device, 10...Step part,
11... Drain hole.

Claims (1)

[Scope of utility model registration request] A water backflow prevention device for an exhaust pipe of an outboard motor, wherein an exhaust pipe connected to an engine is provided protrudingly opened in a drive shaft housing, and exhaust gas is discharged into water from a propeller section below the drive shaft housing. An exhaust pipe connected to the engine is configured as a small-diameter exhaust pipe, a large-diameter exhaust pipe is connected to the lower part of the small-diameter exhaust pipe to form a stepped portion, and a water drain hole is provided in the stepped portion, and the small-diameter exhaust pipe is provided with a drain hole. 1. A water backflow prevention device characterized in that a lower end of the pipe protrudes a predetermined length into an upper end of a large-diameter exhaust pipe.