JP3871157B2 - Outboard motor exhaust structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of an exhaust structure for an outboard motor.
[0002]
[Prior art]
In an outboard motor, the exhaust of the engine is discharged into the water, so that it is difficult for the exhaust to escape during idle operation. For this reason, a method is known in which part of the exhaust is led to the idle expansion chamber and exhausted into the air. . FIG. 8 is a cross-sectional view showing a conventional exhaust structure proposed in Japanese Patent Laid-Open No. 8-284655.
[0003]
An exhaust passage 201 a and a cooling water passage 201 b are formed in the engine support 201 that supports the engine, and are fixed on the upper case 206. An oil pan 202 is fixed to the lower part of the engine support 201, and an exhaust pipe 203 is fixed so as to penetrate the oil pan 202, and a main expansion chamber 205 is formed below the exhaust pipe 203. A mounting flange 203b is welded to the upper part of the exhaust pipe 203, an idle exhaust hole 203a is formed in the lower part thereof, and a shielding member 203c is welded at a predetermined interval facing the idle exhaust hole 203a. ing. The mounting flange 203 b of the exhaust pipe 203 is fixed to the oil pan 202 and the engine support 201 with bolts 204.
[0004]
A partition wall 206a is integrally formed in the upper case 206 with a gap from the oil pan 202, and a communication port 206c is formed in the partition wall 206a. Thus, an idle expansion chamber 207 is formed between the partition wall 206a and the upper case 206, and an air exhaust port 206b that opens to the outside is formed in the idle expansion chamber 207. With this configuration, during idle operation, a part of the exhaust enters the idle expansion chamber 207 via the communication port 206c between the idle exhaust hole 203a of the exhaust pipe 203, the oil pan 202 and the upper case 206, as shown by the arrows in the figure. The water that has cooled the engine is discharged from the air exhaust hole 206b through the cooling water passage 201b of the engine support 201 from below the engine, between the oil pan 202 and the upper case 206, and between the oil pan 202 and the exhaust. The oil pan 202 and the exhaust pipe 203 are cooled by flowing between the pipes 203.
[0005]
[Problems to be solved by the invention]
However, in the conventional exhaust structure, the exhaust gas is bent from the exhaust pipe 203 through the idle exhaust hole 203a and bent at a right angle during the idling operation, so that the negative pressure increases when the engine misfires, etc. Water and cooling water flowing down from the engine enter the engine through the idle exhaust hole 203a, and exhaust gas is difficult to escape during high-speed output and the desired engine performance cannot be obtained. Have.
[0006]
The present invention solves the above-described conventional problems, and prevents cooling water flowing down from the engine from entering the engine through the idle exhaust hole, and improves engine performance at high-speed output. The purpose is to provide an outboard motor that can be used.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an exhaust structure for an outboard motor according to the present invention is fixed to a casing 10, and includes an engine support 12 that supports the engine 11, and an oil that is mounted in the casing below the engine support. A pan 29, an exhaust pipe 30 attached so as to penetrate the oil pan, a space 40 formed between the oil pan and the exhaust pipe, and a cooling water passage 33b connected to the space. In claim 1, the exhaust pipe 30 has an oil pan mounting flange 30a at an upper end, an idle exhaust hole 30b branched from the exhaust passage is formed in the mounting flange, and an exhaust pipe is formed below the idle exhaust hole. a shielding member 30c so as to cover the outer periphery is provided, this on the inner periphery of the mounting portion 29e of the oil pan 29, the notch 29m facing the idle exhaust hole 30b is formed The features. In addition, the number added to the said structure contrasts with drawing in order to make an understanding of this invention easy, and this invention is not limited at all by this.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an embodiment of an outboard motor according to the present invention. The outboard motor 1 includes a clamp bracket 3 that is detachably attached to the rear portion of the hull 2, a swivel bracket 6 that is pivotally supported by the clamp bracket 3 via a horizontal shaft 5 in the vertical direction, and the swivel bracket 6 includes a steering bracket 7 pivotally supported through a vertical shaft so as to be rotatable in a horizontal direction, and a propulsion unit 9 supported by the steering bracket 7 via a mount 8. The steering bracket 7 and a guide exhaust 12 described later are also supported via a mount.
[0009]
The propulsion unit 9 has an upper case 10 supported by the steering bracket 7, a guide exhaust 12 is fixed to the upper part of the upper case 10, and an engine 11 is attached to the upper part of the guide exhaust 12. A lower cowling 13 that covers the lower part of the engine 11 is attached to the guide exhaust 12, and an upper cowling 15 that covers the upper part of the engine 11 is detachably attached to the lower cowling 13. An apron cover 16 that covers the periphery of the guide exhaust 12 is attached to the guide exhaust 12, and a lower case 17 is attached to the lower portion of the upper case 10 to constitute a casing as a whole. In addition, 19 is a cooling water intake, 20 is a propeller, 21 is a steering handle, 22 is a shift lever.
[0010]
The engine 11 supported by the guide exhaust 12 is, for example, a two-cylinder four-cycle engine, and includes two cylinders arranged in a horizontally placed state and a crankshaft 23 arranged in a vertically placed state. A drive shaft 25 is vertically disposed in the upper case 10 and the lower case 17, an upper end thereof is connected to the crankshaft 23, and a lower end thereof is connected to the propeller shaft 27 via a bevel gear 26. The guide exhaust 12 is provided with an oil pump 28, an oil pan 29 is attached to the lower portion of the guide exhaust 12, and an exhaust pipe 30 extending from the engine 11 is attached so as to penetrate the oil pan 29.
[0011]
A cooling water supply pipe 31 is disposed in the upper case 10 and the lower case 17 in a vertical direction substantially parallel to the drive shaft 25, and a cooling water pump 32 is provided at an intermediate portion of the drive shaft 25. The cooling water pump 32 supplies the water sucked from the cooling water inlet 19 to the water jacket of the engine 11 through the cooling water supply pipe 31, and the water that has cooled the engine 11 falls below the engine and drops into the oil pan 29 and The exhaust pipe 30 is cooled.
[0012]
2 is a partially enlarged cross-sectional view around the oil pan in FIG. 1, FIG. 3 is a cross-sectional view taken along the line XX in FIG. 2, and FIG. 4 is a perspective view of the oil pan. 1 shows the upper case 10, the guide exhaust 12, the drive shaft 25, the oil pan 29, the exhaust pipe 30, and the cooling water supply pipe 31 described in FIG. In FIG. 3, the upper case 10 is fixed to the guide exhaust 12 by a bolt 34a, and the oil pan 29 is fixed to the guide exhaust 12 by a bolt 34b.
[0013]
2, the guide exhaust 12 includes an oil seal 32 that supports the drive shaft 25, a cooling water passage 33a connected to the cooling water supply pipe 31, a cooling water passage 33b through which water that has cooled the engine flows down, and an exhaust pipe. A main exhaust passage 35 connected to 30, a drain hole 37 for draining water accumulated in the arrangement portion 36 of the oil pump 28 (FIG. 1), and an idle exhaust passage 38 are formed.
[0014]
2 to 4, an oil pan 29 is attached to the lower portion of the guide exhaust 12. The oil pan 29 is integrally formed of an aluminum alloy, and an oil reservoir 29d formed in a substantially annular shape in plan view by an outer wall 29a and a bottom wall 29b, and an inner wall 29c formed at intervals from three sides of the outer wall 29a. A mounting portion 29e integrally formed on the upper portion of the inner wall 29c, an exhaust connection path 29f formed in the mounting portion 29e, an exhaust hole 29g formed on a surface of the outer wall 29a that does not have the inner wall 29c, and a fixed And a cooling water supply pipe support hole 29k and a drain hole 29i formed in the fixing flange 29h, and three drain holes 29j formed in the attachment portion 29e. The drain holes 29i and 29j are connected to a cooling water passage 33b formed in the guide exhaust 12.
[0015]
On the other hand, an attachment flange 30a is fixed to the upper end portion of the exhaust pipe 30 by welding, and an idle exhaust hole 30b branched from the exhaust passage is formed on the outer periphery of the exhaust pipe 30 in the attachment flange 30a. Further, a shielding member 30c is welded to the mounting flange 30a at a predetermined interval so as to cover the outer periphery of the exhaust pipe 30 below the idle exhaust hole 30b, and the exhaust discharged from the idle exhaust hole 30b flows downward. I am doing so. This shielding member 30c is for preventing corrosion caused by exhaust hitting the inner wall 29c. A notch 29m is formed on the inner periphery of the mounting portion 29e of the oil pan 29 so as to face the idle exhaust hole 30b.
[0016]
The mounting flange 30 a of the exhaust pipe 30 is in contact with the mounting portion 29 e of the oil pan 29, and the exhaust pipe 30 is fixed to the oil pan 29 and the guide exhaust 12 by bolts 39. At this time, the length of the exhaust pipe 30 is designed so that the lower end of the exhaust pipe 30 is substantially flush with the bottom wall 29 b of the oil pan 29. With this configuration, the engine exhaust passes through the exhaust passage 35 of the guide exhaust 12, the exhaust passage 29 f of the oil pan 29, and the exhaust pipe 30 to the main expansion chamber 41 formed below the oil pan 29 and the exhaust pipe 30. In addition, a space 40 is formed between the outer periphery of the exhaust pipe 30 and the inner wall 29c of the oil pan 29. This space 40 is connected to the cooling water passage 33b, and the exhaust pipe 30 and the oil pan are cooled by cooling water flowing down from the engine. 29 is cooled.
[0017]
A partition wall 10b is integrally formed on the outer wall 10a of the upper case 10 at a distance from the oil pan 29, and an idle expansion chamber 42 is formed between the outer wall 10a and the partition wall 10b. An exhaust guide member 43 is provided in the idle expansion chamber 42, and an air exhaust hole 44 that exhausts the exhaust in the idle expansion chamber 42 to the outside is discharged to the outer wall 10 a of the upper case 10 and water that has entered together with the exhaust is discharged. A drain hole 45 is formed.
[0018]
As shown in FIG. 3, an oil suction portion 28a is accommodated in the oil pan 29, and is connected to the oil pump 28 of FIG. 1 via an oil supply pipe 28b. As shown in FIG. 2, a drain discharge port 46 for discharging oil is formed at the bottom of the oil pan 29 and sealed with a screw 47. A rubber guide member 49 is fixed to the periphery of the drain discharge port 46 at the bottom of the oil pan 29. The guide member 49 extends vertically downward and is formed in a through hole 10c formed in the outer wall 10a of the upper case 10. Has been inserted. A cooling water supply pipe 31 is in contact with the side surface of the oil pan 29 via a positioning member 31a.
[0019]
FIG. 5 is a view for explaining the idle exhaust passage 38 of the guide exhaust 12 of FIG. 2, FIG. 5 (A) is a bottom view, and FIG. 5 (B) is a cross-sectional view of FIG. It is sectional drawing seen in the arrow direction along the line. The idle exhaust passage 38 in FIG. 2 is a cross-sectional view as seen in the direction of the arrow along the line CC in FIG. The guide exhaust 12 is formed with a rib 12a having a notch 12b, and a rubber throttle member 51 is attached to the rib 12a. The throttle member 51 has a bifurcated locking piece 51a at both ends and a notch 51b having a concave cross section formed at the center, and an idle exhaust passage 38 is formed by the notch 51b. In this example, the guide exhaust 12 common to models with different displacements can be adopted by arbitrarily changing the area of the notch 51b.
[0020]
6 is an enlarged cross-sectional view of the drain hole 37 of the guide exhaust 12 of FIG. A check valve 52 is mounted at the outlet of the drain hole 37. The check valve 52 is formed by cutting a rubber valve body 52a to form the valve 52. The water accumulated in the guide exhaust 12 can be drained from the drain hole 37, and water is generated by the trailing wave when the hull suddenly decelerates. Intrusion of water from the hole 37 is prevented.
[0021]
The operation of the present invention having the above-described configuration will be described. During idle operation, a part of the exhaust is, as shown by the arrows in the figure, the idle exhaust hole 30b, the exhaust hole 29g, the oil pan 29 and the outer wall of the upper case 10 of the exhaust pipe 30. During the period 10 a, the air enters the idle expansion chamber 42 through the exhaust passage 38 and is discharged from the air exhaust hole 44. The cooling water pump 32 driven by the drive shaft 25 supplies water sucked from the cooling water intake port 19 to the water jacket of the engine through the cooling water supply pipe 31, and guides the water that has cooled the engine from below the engine. Through the cooling water passage 33 b of the exhaust 12 and drain holes 29 i and 29 j formed in the oil pan 29, the oil pan 29 flows down between the oil pan 29 and the outer wall 10 a of the upper case 10 and into the space 40 inside the oil pan 29. And the exhaust pipe 30 is cooled.
[0022]
In the present embodiment, during idle exhaust, the exhaust flows along the flow direction of the cooling water, so that the negative pressure increases during engine misfire and the like, and the water around the exhaust pipe and the cooling water flowing down from the engine It is possible to prevent the engine from entering the engine through the idle exhaust hole 30b, and the engine performance can be improved because the exhaust can easily escape during high-speed output. In particular, in the case of a two-cylinder four-cycle engine, since the two cylinders alternately explode every time the crankshaft makes one revolution, a large negative pressure is likely to be generated.
[0023]
FIG. 7 is a partially enlarged sectional view similar to FIG. 2 showing a reference example of the present invention. In addition, the same number is attached | subjected to the structure same as FIG. 2, and description is abbreviate | omitted. In this reference example , a cylindrical idle exhaust pipe 39 d is attached to the upper part of the exhaust pipe 30 in the horizontal direction toward the space 40. With this configuration, it is possible to increase the area for idle exhaust.
[0024]
【The invention's effect】
As is apparent from the above description, according to the first aspect of the present invention, the exhaust gas flows along the flow-down direction of the cooling water during idle exhaust, so the negative pressure increases during engine misfire and the like, and the exhaust pipe The surrounding water and cooling water flowing down from the engine can be prevented from entering the engine through the idle exhaust hole,
Further, according to the invention of claim 2, it is possible to increase the area for idle exhaust,
Further, according to the invention described in claim 3, it is possible to more effectively prevent water from entering the engine.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of an outboard motor according to the present invention.
FIG. 2 is a partially enlarged cross-sectional view around the oil pan of FIG.
3 is a cross-sectional view taken along the line XX of FIG. 2 as viewed in the direction of the arrow.
4 is a perspective view of the oil pan of FIG. 2. FIG.
5 is a view for explaining an idle exhaust passage of the guide exhaust of FIG. 2, FIG. 5 (A) is a bottom view, and FIG. 5 (B) is a line BB of FIG. 5 (A). It is sectional drawing seen in the arrow direction along.
6 is an enlarged cross-sectional view of a drain hole of the guide exhaust of FIG. 2. FIG.
7 is a partially enlarged cross-sectional view similar to FIG. 2, showing another embodiment of the present invention.
FIG. 8 is a cross-sectional view showing an exhaust structure of a conventional outboard motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Upper case (casing) 11 ... Engine 12 ... Guide exhaust (engine support body) 29 ... Oil pan 30 ... Exhaust pipe, 30a ... Mounting flange, 30b ... Idle exhaust hole 30c ... Shield member, 30d ... Idle exhaust pipe, 33b ... cooling water passage 40 ... space

Claims (1)

An engine support that is fixed to the casing and supports the engine, an oil pan that is attached to the casing below the engine support, an exhaust pipe that is attached to penetrate the oil pan, and the oil pan An idle exhaust having a space formed between the exhaust pipe and a cooling water passage connected to the space, the exhaust pipe having an oil pan mounting flange at an upper end, and branching from the exhaust passage to the mounting flange A hole is formed, and a shielding member is provided under the idle exhaust hole so as to cover the outer periphery of the exhaust pipe. A cutout portion is formed on the inner periphery of the oil pan mounting portion so as to face the idle exhaust hole. exhaust structure of the outboard motor, characterized in that there.

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