JPH09254884A - Cowling air duct structure of outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve ventilation in a top cowling by opening an air exhaust hole on the upper rear surface of a top cowling, and opening an air intake hole on the front side surface. SOLUTION: A space part covered with an air duct cover 2c is partitioned into an air intake chamber and an air exhaust chamber to form an air duct in which air flows from the outside of a top cowling 2 through an air intake hole 76 of the air duct cover 2c, an air intake chamber, and an air intake port of an upper cowling 2a into the inside of a top cowling 2. Further, an air duct is constructed in such a manner that air flows from the inside of the top cowling 2 through an air discharge port of the upper cowling 2a, an air discharge chamber, and an air discharge hole 77 of the air duct cover 2c to the outside of the top cowling 2. Accordingly, by the action of wind from the front during traveling, air can be positively discharged from the air discharge hole 77 to the outside of the top cowling 2, so that ventilation in the top cowling can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outboard motor mounted on a small boat, and more particularly to a structure of an air duct formed on a top cowling of the outboard motor.

[0002]

2. Description of the Related Art In an outboard motor mounted on a small boat, an engine in which cylinders are arranged in a vertical direction so that a crankshaft extends vertically is usually housed in a top cowling on an upper part of the outboard motor. In addition, an air hole serving as an air duct is opened in the vicinity of the upper rear end of the top cowling, and the air supplied to the engine is taken into the top cowling by the air hole, while the temperature becomes high during operation. The air around the engine heated by the engine is discharged to the outside of the top cowling.

[0003]

By the way, in the air duct structure of the conventional outboard motor in which the air hole is opened near the upper rear end of the top cowling as described above, the intake air and the exhaust air are different from each other. Since the air passes through the same air hole, the intake and exhaust efficiencies of the air are low, and the air that is exhausted at a high temperature is mixed with the air that is sucked and supplied to the engine. It also causes a problem of deteriorating efficiency.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an outboard vessel in which an engine is installed in a top cowling at an upper portion of a body as described in claim 1 above. In the machine, an air discharge hole is opened on the upper rear surface of the top cowling, and an air suction hole is opened on the front side surface thereof.

Further, in the cowling air duct structure of the outboard motor according to the above-mentioned claim 1, as described in the above-mentioned claim 2, in the top cowling, a space portion having an air suction hole opened and an air portion. The space portion in which the discharge holes are opened is partitioned by a partition wall so that air in both space portions is not mixed.

Further, in the cowling air duct structure for an outboard motor according to claim 1 or 2, the air intake hole is opened forward as described in claim 3. It is a feature.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a cowling air duct structure for an outboard motor according to the present invention will be described below with reference to the drawings.

FIG. 1 is an external view of an outboard motor to which an embodiment of the cowling air duct structure of the present invention is applied, as seen from the starboard side. The outboard motor 1 includes a top cowling 2
Each component is housed in a housing composed of an upper case 3, a lower case 4, and the top cowling 2 is composed of an upper cowl 2a, a bottom cowl 2b, and an air duct cover 2c.
Has an upper part covered with an apron 5, a propeller 6 is attached to the lower case 4, and a mounting member 7
It is attached to the rear tail plate of the hull 8 via the so as to be vertically and horizontally rotatable.

2 to 5 show the installation state of each component inside the housing of the outboard motor 1, FIG. 2 shows the inside of the top cowling 2 as seen from the starboard side, and FIG. 3 shows its port side. FIG. 4 shows the inside of the top cowling 2 as seen from above, and FIG. 5 shows the inside of the upper case 3 as seen from the starboard side.

The outboard motor 1 has a 4-cycle 4-cylinder L-type engine 10 in which the cylinders are arranged in a vertical direction and is fixed to the upper surface of an exhaust guide 11 installed between the bottom cowl 2b and the upper case 3. And the upper surface side is the cover member 1
It is stored in the top cowling 2 on the upper side in a state covered with 2.

As shown in FIGS. 2 to 4, the engine 10 includes a head cover 13, a cylinder head 14, a cylinder block 15 forming a part of a crank body and a crank chamber, and a crank case 16 of the engine 10. Are integrally connected along the front-rear direction of the hull, and the crankcase 16 side is the front part and the head cover 13 side is the rear part.

The cylinder head 14 is provided with intake / exhaust valves 17 and 18 for each cylinder, and cam shafts 20 and 21 for driving the valves 17 and 18 are arranged so that their rotation axes are vertical. In addition, the cam cap 22 covered by the head cover 13 and the bearing portion of the cylinder head 14 are pivotally supported, and cam pulleys 23, 24 are fixed to the upper ends of the cam shafts 20, 21, respectively.

In the crank chamber 25 defined by the front portion of the cylinder block 15 and the crankcase 16,
A crankshaft 26 is axially supported so that the rotation axis direction is the vertical direction, a flywheel 27 is fixed to the upper end of the crankshaft 26, and a timing pulley 30 is fixed below the flywheel 27. The timing pulley 30 and the cam pulleys 23, 2
4, a timing belt 28 for transmitting the rotation of the crankshaft 26 to the camshafts 20 and 21 of the intake / exhaust valves 17 and 18 is stretched.

For the timing belt 28,
An idler 29 is arranged to prevent the slack, and the idler 29 is always urged in a direction to press the timing belt 28 inward by a tensioner (not shown) formed by a gas cylinder containing gas.

On the front left side of the engine 10, a surge tank 31 is installed which is integrally connected to the front surface of the crankcase 16 and has an intake port 31a serving as an air introduction portion of the engine intake path opened at the upper end. Each intake passage 32 extending from the surge tank 31 is connected via a throttle portion 33 to an intake port 34 of each cylinder formed in the left side portion of the cylinder head 14 at intervals in the vertical direction. ing.

Exhaust ports 35 connected to the combustion chambers of the cylinders are formed in the right side portion of the cylinder head 14 at intervals in the vertical direction. An exhaust passage 36 for collecting and exhausting exhaust gas to the lower side of the engine main body is provided with a cylinder 37.
The exhaust passage 36, which is formed integrally with the cylinder block 15 on the right side of and extends vertically in the cylinder block 15, has its lower end connected to the exhaust passage 11 a of the exhaust guide 11.

In the above engine 10, an oil pump 38 for sucking lubricating oil from an oil pan arranged below the exhaust guide 11 is inserted into an oil passage provided in the engine body. A thermostat valve 41 for controlling the discharge amount of the cooling water according to the temperature around the cylinder and the combustion chamber with respect to the cooling water cooling path provided in the engine body. A pressure valve 42 for releasing cooling water from the cooling passage is provided so that the water pressure in the cooling passage does not exceed a predetermined value.

A fuel pump 43 for supplying fuel to the engine 10 from a fuel tank (not shown) installed in the hull 8 is arranged on the intake side of the engine 10. A pilot water supply pipe 44 for taking out a part of the cooling water from the cooling passage of the engine body and discharging it as pilot water from the water outlet 45 of the top cowling 2 is connected to the exhaust side thereof.

As shown in FIG. 5, the upper case 3 located below the top cowling 2 is provided with a water reservoir 50 for temporarily receiving the cooling water returned from the engine 10, and the water reservoir 50 is defined. In a state of being isolated from the section 50,
A drive shaft 51 having an upper end connected to the crank shaft 26 of the engine 10 is vertically penetrated so that the lower end portion extends into the lower case 4.

A drive shaft 51 passing through the upper case 3
A water pump 52 that is driven in association with the rotation of the drive shaft 51 is installed in the vicinity of the lower case 4 of FIG.
A cooling water suction pipe extending downward is connected to a water inlet in the lower case 4, and an upward cooling water supply pipe 53 extending through the upper case 3 to the engine 10 is connected.
Is connected.

On the other hand, the water reservoir 50 of the upper case 3 is provided with an oil pan 54 having a bottom so as to be in close contact with the lower surface of the exhaust guide 11 and the upper open portion thereof is closed by the lower surface of the exhaust guide 11. The oil pan 54 is integrally provided with a cylindrical exhaust pipe insertion portion 54a which vertically penetrates a space portion inside the oil pan 54 from the vicinity of the center of the bottom portion thereof.

Further, below the oil pan 54 of the water reservoir portion 50, an exhaust gas discharge port 55a is provided on the bottom wall so that the open upper surface thereof is covered by the lower surface of the oil pan 54 including the exhaust pipe insertion portion 54a. Muffler (exhaust gas expansion chamber) 5
5 is installed, and the internal space of the muffler 55 communicates with an exhaust passage (not shown) defined in the lower case 4 via an exhaust gas outlet 55a.

An exhaust pipe 56 connected to the exhaust passage 11a of the exhaust guide 11 is attached to the exhaust pipe insertion portion 54a of the oil pan 54, and the lower end of the exhaust pipe 56 projects downward from the oil pan 54. Muffler 55
The interior space of the muffler 55 is opened inside and communicates with the exhaust passage 36 of the engine 10 via the exhaust pipe 56 and the exhaust passage 11 a of the exhaust guide 11.

Inside the oil pan 54, the oil pan 5
The suction pipe 57 for sucking the oil accumulated in the No. 4 and sending it to the oil pump 38 of the engine 10
It is provided so as to protrude downward from the lower surface of the exhaust guide 11.

On the peripheral wall of the oil pan 54, the oil pan 5
4 is integrally formed with a water conduit 58 for overflowing water in the water reservoir 50 surrounding the water reservoir 4, and the water passage of the water conduit 58 with the water inlet opening on the water reservoir 50 side is
The water drop port 3a of the upper case 3 is inserted through a water passage portion 55b integrally formed on the upper end of the peripheral wall of the muffler 55.
Is communicated to.

In the upper case 3, a drainage passage 59 extending from the water drop port 3a to the lower case 4 is defined below, and an idle expansion chamber 60 communicating with the muffler 55 is defined above. Idle expansion chamber 6
At 0, an exhaust hole 61 and a drain hole 62 communicating with the outside of the machine are opened.

Although not shown, the lower case 4 located below the upper case 3 has a lower end portion of a drive shaft 51 penetrating the upper case 3 pivotally supported, and the lower end portion of the drive shaft 51 is The rotary shaft of the propeller 6 mounted on the lower case 4 is connected via the shift conversion gear portion.

Although not shown, the lower case 4
Is provided with an inlet for cooling water sucked up by the water pump 52, and the upper case 3
An exhaust passage for discharging the exhaust gas sent through the muffler 55 into the water with the rotation of the propeller 6 is defined, and cooling for discharging the cooling water dropped from the upper case 3 to the outside of the machine. A water drain is defined.

In the outboard motor 1 in which the respective members are arranged as described above, the air sucked from the intake port 31a of the surge tank 31 is mixed with the fuel supplied by the fuel pump 43 to burn the engine body. After being burned in the chamber,
Exhaust gas is discharged from the exhaust passage 36 below the engine 10, is sent into the muffler 55 through the exhaust passage 11a of the exhaust guide 11 and the exhaust pipe 56, and is discharged from the idle expansion chamber 60 into the atmosphere through the exhaust hole 61. Most of the exhaust gas is discharged while the propeller 6 is rotating, and most of the exhaust gas is discharged from the exhaust gas exhaust port 55 of the muffler 55.
The water is discharged from a through the exhaust passage in the lower case 4 as the propeller 6 rotates.

By the way, in the outboard motor 1 configured as described above, inside the top cowling 2, above the cam pulleys 23, 24, the flywheel 27, the timing belt 28, and the like arranged on the upper surface of the engine. A cover member 12 is installed above the engine 10 so as to cover the above and spread from the position corresponding to the air duct portion of the top cowling 2 to the position corresponding to the intake port 31a of the surge tank 31.

As shown in FIGS. 7 and 8, the cover member 12 has a cover portion 12a which directly covers the cam pulleys 23, 24, the flywheel 27, and the timing belt 28. 12a so as to partially cover the upper cowl 2a from a position corresponding to the air inlet 72 of the upper cowl 2a.
Intake passage forming portion 12 extending to a position corresponding to 1a
b is integrally formed, and the air suction passage 8 is formed by a part of the cover portion 12a and the suction passage forming portion 12b.
1 is formed.

In the air intake passage 81, the air inlet 81a is projected upward at a position corresponding to the air intake port 72 of the upper cowl 2a with respect to the intake passage forming portion 12b.
Is opened, and the suction passage forming portion 12b is protruded from the cover portion 12a toward the surge tank 31, so that the air outlet 81b is opened downward at a position corresponding to the intake port 31a of the surge tank 31. Has been done.

As a result, as shown by the arrow in the figure, the air introduced to the air intake port 72 of the upper cowl 2a is
From the air inlet 81a protruding upward, the air intake passage 81
Through the air outlet 81b to the intake port 31a of the surge tank 31.

Further, as shown in FIGS. 9 and 10, the cover member 12 is adjacent to the side of the air intake passage 81 and partially covers the cover portion 12a from above. A discharge passage forming portion 12c extending from the vicinity of the flywheel 27 to the air discharge port 73 of the upper cowl 2a is integrally formed therewith, and a part of the cover portion 12a and the suction passage forming portion 12b and the discharge passage forming portion 12c are formed. An air discharge passage 82 is formed by the portion 12c.

In the air discharge passage 82, the cover portion 1
The peripheral space of the flywheel 27 and the air exhaust passage 82 are provided in a part of the side wall of the portion surrounding the flywheel 27 of 2a.
The air inlet 82a is opened so as to communicate with, and an air outlet 82b is opened at the position corresponding to the air outlet 73 of the upper cowl 2a so as to project upward in the discharge passage forming portion 12c.

As a result, as shown by the arrow in the drawing, the air heated and rising inside the top cowling 2 is rotated from below the cover member 12 by the rotation of the flywheel 27 having the fan 27a on the upper surface. Air inlet 82a
, The air outlet 82 is opened in the cover portion 12a, the air outlet 82 is passed through, and the air outlet 82 is opened.
It is made to flow from b to the air discharge port 73 of the upper cowl 2a.

In the cover portion 12a, a water draining hole 83 is formed in the middle of the air intake passage 81, and a water draining hole 84 is also formed in the middle of the air discharge passage 82. .

In the outboard motor 1 of the present embodiment in which the air intake passage 81 and the air discharge passage 82 are formed inside the top cowling 2 as described above, the air duct for letting in and out the air flowing through these air passages. The portion is formed in the rear portion of the upper surface of the upper cowl 2a with respect to the top cowling 2 and in the portion covered by the air duct cover 2c.

That is, as shown in FIG. 6, a pair of air suction ports 72, 72, an air discharge port 73, and a partition wall 74 are integrally provided in a stepped portion at the rear of the upper surface of the upper cowl 2a. On the other hand, in the air duct cover 2c that covers the relevant portion, the air suction holes 7 are formed on the left and right side surfaces thereof.
6 and 76 are opened respectively, and the air discharge hole 7 is formed on the rear surface thereof.
7 is open.

As a result, the space portion covered by the air duct cover 2c is separated by the partition wall 74 into the air suction chamber 71a.
And the air discharge chamber 71b are divided into the top cowling 2
The air duct is constructed so that air flows from the outside of the top cowling 2 through the air suction hole 76 of the air duct cover 2c, the air suction chamber 71a and the air suction port 72 of the upper cowl 2a. An air duct is constructed so that air flows from the inside of the cowling 2 to the outside of the top cowling 2 through the air discharge port 73 of the upper cowl 2a and from the air discharge chamber 71b to the air discharge hole 77 of the air duct cover 2c. .

As described above, according to the cowling air duct structure of the outboard motor of the present embodiment in which the air intake hole 76 and the air exhaust hole 77 are opened in the air duct cover 2c of the top cowling 2, the wind from the front during traveling. By receiving the negative pressure, a negative pressure acts on the air exhaust hole 77 opened on the rear surface of the top cowling 2 so as to suck the internal air to the outside of the top cowling 2. As a result, the air is positively discharged, the ventilation in the top cowling 2 becomes good, and the temperature rise in the top cowling 2 due to the engine heat can be suppressed.

Further, since the air in the top cowling 2 is not discharged from the air suction hole 76, the air can be efficiently sucked in, and the surge tank 31 of the surge tank 31 passes from the air suction hole 76 through the air suction passage 81. Inlet 3
Since sufficient air can be supplied to 1a, the negative pressure in the intake passage of the engine can be reduced.

In the present embodiment shown in FIG. 6, the air intake holes 76 opened on both the left and right side surfaces of the air duct cover 2c are planarly opened in a state of being flush with the wall surface of the top cowling 2. However, regarding the air suction hole 76, as shown in FIGS. 11A to 11C, the wall surface of the cowling 2 is obliquely bulged forward, or the air suction hole 76 is shown in FIGS. ), The wall surface of the cowling 2 may be obliquely recessed rearward so that each air intake hole 76 can be opened forward with an angle to the surface of the top cowling 2. is there.

In the case where the air intake hole 76 is opened forward as described above, the dynamic pressure works so as to push the air from the front into the air intake hole 76 during traveling, and the air intake is performed more effectively. Be seen.

Further, in this embodiment, the air suction hole 76
Since the air discharge hole 77 and the air discharge hole 77 are separated by the partition wall 74, the air supplied to the engine through the air suction hole 76 is discharged from the air discharge hole 77 to the outside of the top cowling 2. It is possible to reliably prevent the mixture of heated air.

Although one embodiment of the cowling air duct structure for an outboard motor of the present invention has been described above, the present invention is
As described above, the outboard motor is limited to the one having the air duct cover 2c for the upper cowl 2a and the cover member 12 having the air intake passage 81 and the air discharge passage 82. Not what is done,
It can also be implemented for other outboard motors having a conventionally known structure.

[0047]

According to the cowling air duct structure for an outboard motor of the present invention as described above, it is possible to enhance the discharge efficiency of the air heated in the cowling and suppress the temperature rise in the cowling. It is possible to increase the efficiency of intake of air into the cowling and reduce the negative pressure in the engine intake passage, and it is possible to prevent deterioration of engine intake efficiency due to mixing of high-temperature air. It is possible to improve.

[Brief description of drawings]

FIG. 1 is a side view of an outboard motor to which a cowling air duct structure of the present invention is applied, as seen from a starboard side.

FIG. 2 is a partial cross-sectional explanatory view showing the internal structure of the top cowling portion of the outboard motor shown in FIG. 1, as seen from the starboard side.

FIG. 3 is a partial cross-sectional explanatory view showing the internal structure of the top cowling portion of the outboard motor shown in FIG. 1, as seen from the port side.

4 is a cross-sectional explanatory view showing the internal structure of the top cowling portion of the outboard motor shown in FIG. 1, as viewed from above.

5 is an explanatory cross-sectional view seen from the starboard side showing the internal structure of the upper case portion of the outboard motor shown in FIG.

FIG. 6 is a top view of a top cowling showing an embodiment of a cowling air duct structure for an outboard motor of the present invention.

7 is a vertical cross-sectional explanatory view showing the flow of intake air in the top cowling of the outboard motor shown in FIG.

8 is a cross-sectional explanatory view showing a state of the intake air flow shown in FIG. 7 as viewed from above.

9 is a vertical cross-sectional explanatory view showing the flow of exhaust air in the top cowling of the outboard motor shown in FIG.

10 is a cross-sectional explanatory view showing a state of the exhaust air flow shown in FIG. 9 viewed from above.

FIG. 11 shows an air intake hole portion in another embodiment of the cowling air duct structure for an outboard motor of the present invention (A).
The side view, the cross-sectional view along the BB line of (B) figure A, and the vertical cross-sectional view along the CC line of (C) figure.

12 (A) is a side view showing an air intake hole portion in still another embodiment of the cowling air duct structure for an outboard motor of the present invention, and FIG. 12 (B) is a cross-sectional view taken along the line BB of FIG. , And (C) is a vertical cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 2 Top cowling 10 Engine 71a Air intake chamber (space part in which air intake hole is opened) 71b Air discharge chamber (space part in which air discharge hole is opened) 74 Partition wall 76 Air intake hole 77 Air discharge hole

Claims (3)

[Claims] 1. An outboard motor in which an engine is installed in a top cowling on an upper part of an airframe, wherein an air discharge hole is opened on a rear surface of an upper portion of the top cowling and an air suction hole is opened on a front side surface thereof. The cowling air duct structure of the outboard motor, which is characterized in that 2. In the top cowling, a space portion in which an air suction hole is opened and a space portion in which an air discharge hole is opened are partitioned by a partition wall so that air in both space portions is not mixed. The cowling air duct structure for an outboard motor according to claim 1, wherein: 3. The cowling air duct structure for an outboard motor according to claim 1, wherein the air intake hole is opened forward.