JP2001199392A - Outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compactly arrange a breather pipe even in a relatively small engine cover, in an outboard engine in which a four-cycle engine is provided in which a camshaft is connected to a crankshaft by a belt transmission means having a driven pulley fixed to one end of the camshaft over a cylinder head and a timing belt wound on the pulley, and a part corresponding to at least the driven pulley is covered with a belt cover, and at least the upper half part of the engine is covered with the engine cover. SOLUTION: One end of the breather pipe 121 that extends along the outer surface of the belt cover 60 and is fixed to the belt cover 60 at its intermediate part is connected to the upper part of a head cover 45. The other end of the breather pipe 121 is connected to an intake device 73 that is disposed on one side of an engine block 43 and connected to the cylinder head 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a valve operating mechanism having a camshaft having an axis parallel to a crankshaft housed in a valve operating chamber formed between a cylinder head and a head cover. A four-stroke engine in which the camshaft and the crankshaft are connected by belt transmission means having a driven pulley fixed to one end of a shaft and a timing belt wound around the pulley, and at least a portion corresponding to the driven pulley is covered with a belt cover. And an improvement in an outboard motor in which at least an upper half of the engine is covered with an engine cover.

[0002]

2. Description of the Related Art Conventionally, such an outboard motor is already known, for example, from Japanese Patent Application Laid-Open No. H8-100707.

[0003]

In such an outboard motor, it is desirable that the breather pipe for guiding the breather gas from the head cover to the intake device be subjected to a pipe treatment while avoiding an increase in the size of the engine cover. 2534
In Japanese Patent Publication No. 670, a breather pipe is treated with such considerations. However, the actual climb 253
In the apparatus disclosed in Japanese Patent No. 4670, a breather pipe is piped so as to extend laterally from a vertically intermediate portion of a head cover, and such a pipe structure has a sufficient clearance between a side surface of a cylinder head and an engine cover. This is a condition, and is difficult to apply when the engine cover is relatively small and it is difficult to secure such clearance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an outboard motor in which a breather pipe can be compactly piped even with a relatively small engine cover.

[0005]

To achieve the above object, the present invention provides an engine block for rotatably supporting a vertically extending crankshaft, a cylinder head connected to the engine block, and a cylinder head. A head cover that forms a valve chamber between the cylinder cover and the cylinder cover, a valve mechanism having a camshaft having an axis parallel to the crankshaft and housed in the valve chamber, and the cylinder A belt transmission means for connecting the camshaft and the crankshaft with a driven pulley fixed to one end of the camshaft above the head and a timing belt wound around the pulley, and corresponding to at least the driven pulley; At least the upper half of a four-stroke engine having a belt cover that covers the engine cover. In the outboard motor to be covered, one end of a breather pipe extending along the outer surface of the belt cover and having an intermediate portion fixed to the belt cover is connected to a breather chamber formed in the head cover, and an upper portion of the head cover is formed. And the other end of the breather pipe is connected to an intake device arranged on one side of the engine block and connected to the cylinder head.

According to such a configuration, the breather tube is
Along the outer surface of the belt cover arranged above the cylinder head, it will be extended to the intake device side arranged on one side of the engine block, and one end of the breather pipe will be connected to the top of the head cover. Since the middle portion of the breather pipe is fixed to the belt cover, the breather pipe can be brought close to the belt cover until it comes into contact with the belt cover, and can be piped so as not to protrude sideways from the intake device. Even if it ’s small,
A breather pipe can be compactly installed in the engine cover.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on one embodiment of the present invention shown in the attached drawings.

1 to 14 show an embodiment of the present invention. FIG. 1 is an overall side view of an outboard motor, FIG. 2 is an enlarged longitudinal sectional view of a main part of FIG. 1, and FIG. 3 is an engine cover. 2 is an enlarged sectional view taken along line 3-3 in FIG. 2, FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG. 2 with the engine cover omitted, and FIG. FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG.
7 is an enlarged sectional view taken along the line 7-7 in FIG. 4, and FIG. 8 is an 8-8 in FIG.
9, FIG. 9 is a sectional view taken along line 9-9 in FIG. 6, FIG. 10 is a transverse sectional view of the oil case, taken along line 10-10 in FIG. 11, and FIG. FIG. 12 is a front view of a lid member attached to a rear surface of the oil case, FIG. 13 is an enlarged longitudinal sectional view showing an attachment structure of an exhaust gas sampling pipe, and FIG. 14 is a lower end of an under cover. FIG. 14 is a cross-sectional view taken along the line 14-14 in FIG. 2 for explaining a fixing structure of the device to the casing.

1 and 2, a vertically extending casing 16 is attached to a stern plate 15a of a hull 15, and an engine E of, for example, a two-cylinder four-cycle engine is mounted on the upper end of the casing 16. Is done. At least the upper part (the upper half in this embodiment) of the engine E is covered with an engine cover 13 made of synthetic resin.
, The lower half of the engine E and the upper part of the casing 16 in this embodiment are covered with an under cover 14 made of synthetic resin. A propeller 17 is rotatably supported at the lower end of the casing 16, and the power from the engine E is transmitted to the propeller 17 via a driving force transmitting means 18 built in the casing 16.

The casing 16 comprises an oil case 19,
It comprises an extension case 20 connected to the lower end of the oil case 19 and a gear case 21 connected to the lower end of the extension case 20.
The engine body 22 of the engine E is configured such that the crankshaft 23 extends in the up-down direction.
The propeller 17 is rotatably supported on the gear case 21.

A driving force transmitting means 18 switches between forward and backward movement between a lower end of a driving shaft 24 connected to the crankshaft 23 and extending vertically in the casing 16 and a rear end of a propeller shaft 25 connected to the propeller 17. A mechanism 26 is provided.

The front side of the casing 16, that is, the hull 15
A pipe-shaped swivel case 27 extending vertically is disposed on the side, and a swing arm 28 extending toward the hull 15 is provided on the upper part of the swivel case 27. On the other hand, an inverted J-shaped mounting bracket 29 that can be inserted into and removed from the stern plate 15a from above is attached to and detached from the stern plate 15a of the hull 15 by tightening a push screw 30 screwed to the mounting bracket 29. The pivot arm 28 is pivotally supported by a mounting bracket 29 via a pivot 31 having a horizontal axis.

The mounting bracket 29 is provided with a plurality of pin holes 32. A pin hole (not shown) provided in a locking plate 33 fixed to the swivel case 27.
By inserting the pin 34 into one of the pin holes 32 of the mounting bracket 29, the tilt angle of the casing 16 around the axis of the pivot 31, that is, the outboard motor, can be adjusted.

A swivel shaft 35 rotatably supported by the swivel case 27 is inserted into the swivel case 27, and a mount arm 36 is provided at an upper end of the swivel shaft 35, and a lower end of the swivel shaft 35 is provided. Is provided with a mount block 37.

Referring also to FIG. 3, a support arm 19a disposed above the mount arm 36 is integrally provided at the upper end of the front of the oil case 19 in the casing 16. Is elastically connected to the support arm 19a via a pair of left and right upper mounts 38, 38, and the mount block 37 is elastically connected to the extension case 20 via a lower mount 39. A steering handle 40 extending toward the hull 15 is fixed to the mount arm 36. By operating the steering handle 40 left and right, the casing 16
Can be rotated left and right around the axis of the swivel shaft 35 to steer the outboard motor.

Referring to FIGS. 4 and 5, the engine body 22 includes an engine block 4 integrally provided with a crankcase 43a and coupled to an upper surface of the oil case 19.
3, a cylinder head 44 connected to the engine block 43, and a synthetic resin head cover 45 connected to the cylinder head 44. A valve train chamber 46 is formed between the cylinder head 44 and the head cover 45. .

The engine block 43 is provided with a pair of upper and lower cylinder bores 47, 47 having a cylinder axis extending in the front-rear direction of the outboard motor, and pistons 48, 48 slide in the cylinder bores 47, 47, respectively. Mating is possible. On the other hand, the crankshaft 23 extending vertically in the crankcase 43a is
A support member 50 coupled to an upper portion of the crankcase 43a is rotatably supported by a lower portion of the crankcase 43a. The pistons 48 are connected to the crankshaft 23 via connecting rods 49, 49, respectively. .

A generator 51 and a recoil starter 52 are coaxially connected to the upper end of the crankshaft 23 projecting upward from the support member 50. The generator 51 and the recoil starter 52 are covered by a common cover 53.

In the valve operating chamber 46, the crankshaft 23 is provided.
A valve train 55 including a camshaft 54 having an axis parallel to the shaft is accommodated. The camshaft 54 is rotatably supported by the cylinder head 44. Power is transmitted to the camshaft 54 via a belt transmission means 56. The belt transmission means 56 includes a driving pulley 57 fixed to the crankshaft 23 above the support member 50, and a cylinder head. An endless timing belt 59 is wound around a driven pulley 58 fixed to the upper end of the camshaft 54 above 44.

A portion of the belt transmission means 56 corresponding to the driven pulley 58 is covered with a belt cover 60. That is, the driving pulley 57 of the belt transmitting means 56
Is covered with a cover 53, and the cover 5
Belt cover 6 so as to cover the part that cannot be covered with 3
0 is placed. A pair of arms 60a, 60a are integrally provided at the rear of the belt cover 60 so as to protrude rearward, and pins 45a, 45a integrally provided on the head cover 45 so as to protrude upward. The rear portions of the belt cover 60 are positioned and supported by the head cover 45 by being fitted to the arm portions 60a, 60a via an elastic material. The support member 50 is integrally provided with a support arm 50a extending toward the belt cover 60, and the front portion of the belt cover 60 is supported by the support member 50 by being fastened to the support arm 50a. .

Referring to FIG. 3, the engine block 43 and the cylinder head 4
A pair of intake ports 62... That can communicate with the combustion chambers 61 formed between the four outboard motors 4 are provided on the left side surface of the cylinder head 44 in a posture facing the rear side of the outboard motor. A pair of exhaust ports 63... That can communicate with the combustion chambers 61.

The valve mechanism 55 switches between a pair of intake valves 64 for switching the communication between the combustion chambers 61 and the intake ports 62 and between the intake ports 64 and the communication between the combustion chambers 61 and the exhaust ports 63. A pair of exhaust valves 65 are driven to open and close. The camshaft 54, a rocker shaft 66 having an axis parallel to the camshaft 54 and supported by the cylinder head 44, and each of the intake valves 64. And a pair of intake rocker arms 67... That are swingably supported on a rocker shaft 66 in conjunction with the exhaust valves 65.
And a pair of exhaust rocker arms 68... Which are operatively linked to and are swingably supported by a rocker shaft 66.

Referring to FIG. 5, the camshaft 54 includes
Intake cams 69 corresponding to the intake rocker arms 67.
And the exhaust side cam 7 corresponding to each exhaust rocker arm 68.
Are provided, and the intake rocker arm 67 and the exhaust rocker arm 68 are swung by following each of the cams 69, 70, so that the intake valve 64 and the exhaust valve 65 become each of the cams 69. , 70... Open / close operation with operation characteristics according to the cam profile.

Each of the intake ports 62 of the cylinder head 44.
Is connected to an intake device 73.
A carburetor 74 disposed on one side of the engine block 43 on the side where the intake ports 62 are disposed (that is, on the left side in a posture facing the rear side of the outboard motor);
A suction silencer box 75 connected to the upstream end of
, And an intake manifold 76 connecting the intake ports 62 to each other. The intake manifold 76
The carburetor 74 communicates with each of the intake ports 62.
Are formed integrally with the cylinder head 44 with a pair of intake passages 76a and 76b commonly connected to the cylinder head 44. Also vaporizer 7
4 is a variable venturi type having a bypass type starting device 77, and is particularly configured as a so-called constant vacuum type utilizing negative pressure.

In FIG. 6, the vaporizer body 7 of the vaporizer 74
8, an intake path 79 having a downstream end communicating with an intake manifold 76 is provided. A throttle valve 80 is disposed downstream of the intake path 79, and intake air is supplied upstream of the throttle valve 80. Venturi 81 in the middle of road 79
Is arranged.

A float chamber 82 is connected to the vaporizer main body 78 directly below the intake passage 79, and a float 84 is accommodated in a float chamber 83 formed between the vaporizer main body 78 and the float chamber 82. . In the float chamber 83,
Fuel oil can be supplied from a fuel pump 72 attached to the cylinder head 44.

At the lower part of the carburetor body 78, a fuel nozzle 85 opening to the venturi portion 81 is provided so as to communicate below the fuel oil level in the float chamber 83 via a fuel jet 86, A needle valve 87 is inserted into 85 from above so as to adjust its effective opening area. The needle valve 87 is attached to the lower end of a piston valve 88 supported up and down on the upper part of the carburetor body 78 so as to make the opening area of the venturi section 81 variable, and attached to the upper end of the carburetor body 78. Diaphragm 9 whose peripheral edge is sandwiched between a cap 89 to be formed and a carburetor body 78
The upper end of the piston valve 88 is connected to the center of the zero.

A venturi pressure chamber 91 is formed between the diaphragm 90 and the cap 89, and
An upstream pressure chamber 92 is formed between the carburetor main body 78 and the carburetor main body 78. The venturi pressure chamber 91 communicates with the venturi section 81 through a communication hole (not shown) provided at the lower end of the piston valve 88, and the venturi pressure chamber 91 returns the piston valve 88 to a downward direction. The spring 93 is housed. The upstream pressure chamber 92 communicates with the inside of the intake silence box 75 upstream of the carburetor 74.

An air bleed pipe 94 having a large number of blast holes is connected to the lower part of the fuel nozzle 85. An annular chamber communicating with the upstream pressure chamber 92 is provided between the air bleed pipe 94 and the carburetor body 78. 95 are formed. Thus, air corresponding to the pressure difference between the venturi section 81 and the annular chamber 95 is blown out from the many blast holes into the air bleed pipe 94 to emulsify the fuel in the air bleed pipe 94, whereby the needle valve 87 is effective. Fuel nozzle 85 whose opening area is adjusted
Atomization of fuel ejected from the fuel is promoted.

In such a carburetor 74, when the intake air amount of the intake passage 79 increases to a certain value or more, the venturi section 8
The pressure in the Venturi pressure chamber 91 decreases with the pressure of 1 and a pressure difference is generated between the Venturi pressure chamber 91 and the upstream pressure chamber 92. The pulling force of the diaphragm 90 due to the pressure difference, and the pressing force of the return spring 93, The piston valve 88 is pulled up to a position where the balance is established, and the opening area of the venturi portion 81 increases. Then, since the pressure of the venturi section 81 tends to return to the original level, the venturi section 81
Is controlled to be substantially constant after the intake air amount exceeds a certain value.

In FIG. 7, the carburetor body 78 is provided with a starting passage 96 which connects the upstream end and the lower end of the intake passage 79, bypassing the throttle valve 80 and the venturi portion 81, and is provided with a bypass type starting. The device 77 includes the engine E
At the time of start-up and warm-up operation, it is attached to the carburetor body 78 to adjust the fuel concentration of the air-fuel mixture flowing through the start-up passage 96 bypassing the throttle valve 80 and the venturi section 81.

The bypass-type starting device 77 is provided with a starting fuel nozzle 97 which is opened at an intermediate portion of the starting passage 96 and is provided in the carburetor body 78. Needle valve 98 inserted from
And a starting air bleed pipe 99 inserted into the starting fuel chamber 100 formed between the carburetor body 78 and the float chamber body 82 and communicating with the starting fuel nozzle 97. Are communicated with the float chamber 83, the upper part of the starting fuel chamber 100 is communicated with the upstream air chamber 92, and the starting air bleed pipe 99 has a large number of through holes 1.
01 ... are provided.

The bypass type starting device 77 is provided in the carburetor body 7.
8, a PTC heater and wax (not shown) are housed in the case 102, and the needle valve 98 is heated and expanded by the PTC heater.
Moves up and down to adjust the effective opening area of the starting fuel nozzle 97. At the upper end of the case 102 is provided a coupler 103 for making an electrical connection with a PTC heater.

Such a bypass type starting device 77 is attached to the carburetor body 78 between the intake block 79 of the carburetor body 78 of the carburetor 74 and the engine block 43, and the upper surface of the coupler 103 is attached to the carburetor 74. Are arranged at substantially the same level as the upper surface of the cap 89.

Further, a heater 104 such as a PTC heater different from the PTC heater of the bypass type starting device 77 is embedded in the vaporizer main body 78 as shown in FIGS. Thus, icing of the vaporizer 74 is prevented.

Referring to FIG. 8 and FIG. 9 together, the intake silencer box 75 is made of a synthetic resin connected to the upstream end of the vaporizer 74 and is detachable from the first case member 105. Case member 10 made of synthetic resin connected to
6 and a third case member 107 made of synthetic resin that is detachably connected to the second case member 106.

The first case member 105 is integrally provided with a connecting tube portion 105a connected to the upstream end of the intake passage 79 of the carburetor 74 so as to extend into the first case member 105. At the inner or upstream end of 105a, a frame trap 10 having a large number of through holes is provided.
8 is attached.

First and second case members 105 and 106
A first air passage 109 that guides air in a direction along the cylinder axis of the engine block 43, that is, in a direction substantially along the front-rear direction of the outboard motor, is formed between the engine block 43 and the downstream end of the first air passage 109. , Is connected to the vaporizer 74 via the frame trap 108 and the connecting cylinder 105a.

The third case member 107 is detachably connected to the end of the second case member 106 on the front side along the front-rear direction of the outboard motor.
Inside, a second air passage 110 extending vertically and having a lower end portion, which is an upstream end portion, opened to the outside is formed. In addition, the direction of air flow in the second air passage 110 is set so as to be substantially orthogonal to the direction of air flow in the first air passage 109 at least at the downstream end, that is, the upper end, as shown by arrows in FIGS. In this embodiment, it is set in the left-right direction of the outboard motor.

In the suction silencer box 75, the cleaner element 11 is disposed on a plane substantially parallel to the air flow direction in the first air passage 109 and along the vertical direction of the outboard motor.
2 are housed and fixed so as to be interposed between the upstream end of the first air passage 109 and the downstream end of the second air passage 110.

The cleaner element 112 is sandwiched between the second and third case members 106 and 107. At the connection portion with the third case member 107, the second case member 106 has a square cross section. Are provided integrally with each other, and the first air passage 1 of the support cylinder portion 106a is provided.
A lattice portion 111 is integrally formed at the end on the 09 side. At the downstream end of the third case member 107, a plurality of pressing portions 114 extending in the front-rear direction of the outboard motor are provided integrally, and a frame trap 113 having a large number of through holes comes into contact with the lattice portion 111. The frame trap 113 and the holding portion 114 are inserted into the support cylinder portion 106a as described above.
The cleaner element 112 is inserted into the support cylinder 106a so as to be sandwiched therebetween.

In the intake silence box 75, the air flow direction at the downstream end of the second air passage 110 is set to the left and right direction of the outboard motor, and is set in a plane substantially along the vertical direction of the outboard motor. The second air passage 110 is arranged between the arranged cleaner element 112 and the engine block 43. Note that one of the frame traps 108 and 113 stored in the intake silence box 75, for example, the frame trap 108 can be omitted.

With particular attention to FIG. 5, a partition plate 1 is formed in the head cover 45 in the valve operating chamber 46 to form a breather chamber 118 separated from the valve operating chamber 46 therebetween.
17 is fixed, and the breather chamber 118 of the diaphragm 117 is fixed.
A reed valve 119 that allows the flow of the breather gas from the valve operating chamber 46 to the breather chamber 118 is attached to a portion facing.

Head cover 45 along the left-right direction of the outboard motor
A connection pipe 120 communicating with the breather chamber 118 is provided integrally at a portion deviated rearward from the belt cover 60 at a substantially central portion so as to rise upward, and one end is connected to the connection pipe 120. The other end of the breather tube 121 is
First air passage 1 of intake silence box 75 in intake device 73
09 is connected to the first case member 105 of the intake silence box 75.

Further, the breather pipe 121 extends along the outer surface of the belt cover 60 and is disposed above the intake manifold 76 and the carburetor 74. It is fixed to the outer surface of the belt cover 60 by a fixing member 122 fastened to the outer surface.

With particular attention to FIG.
Is an oil pan 1 opened upward, that is, toward the engine W side.
An oil strainer 124 is provided at the lower end of a suction pipe 125 inserted into the oil pan 123.

The upper end of the suction pipe 125 is connected to an oil suction passage 126 provided in the engine block 43 and the cylinder head 44, and is driven by the camshaft 54 so as to be provided in the cylinder head 44. 127, the oil suction passage 126
Is connected. The oil discharged from the oil pump 127 is supplied to the crankshaft support at the lower part of the crankcase 43a, and is provided to the engine block 43 and the support 50 at the crankshaft support at the support 50. The oil is supplied through the oil supply passage 128 (see FIG. 7).

Referring also to FIG. 10, the front center of the oil pan 123 is formed as a rearwardly curved partition wall 123a, and the upper drive unit is separated from the inside of the oil pan 123 by the partition wall 123a. A shaft chamber 130 is formed at the front of the oil case 19 so as to extend vertically, and the crankshaft 2 is provided in the upper drive shaft chamber 130.
The drive shaft 24 connected to the drive shaft 3 and extending downward is inserted.

A rear portion of the oil pan 123 is formed as a partition wall 123b extending in the left-right direction of the outboard motor. The first cooling water passage 131 isolated from the inside of the oil pan 123 by the partition wall 123b is formed as described above. Oil pan 12
It is formed in the oil case 19 so as to extend up and down on the rear side with respect to 3. Further, on the rear side of the first cooling water passage 131, a passage wall 132 having a partition wall 132a separating the first cooling water passage 131 from the first cooling water passage 131 is provided at one end of the rear outer wall of the oil case 19 at the rear of the passage wall 132. A first exhaust gas passage 133 which is provided integrally with the oil pan 123 so as to form a part and extends vertically is formed in the passage wall 132.

The inside of the extension case 20 connected to the lower end of the oil case 19 has an exhaust expansion chamber 134 communicating with the lower end of the first exhaust gas passage 133 and the first expansion chamber 134.
The lower drive shaft chamber 1 which is disposed in front of the exhaust expansion chamber 134 through the cooling water passage 131 and the lower end of the drive shaft chamber 130
35 and a partition wall 136.

Referring also to FIG. 11, the oil case 1
9 has a rectangular recess 1 facing the rear middle portion of the passage wall 132 constituting the first exhaust gas passage 133.
The recess 137 is covered with a flat plate member 138, and a second cooling water passage 139 is formed in the recess 137 between the oil case 19 and the plate member 138.

A lid member 140 is fastened to the rear outer wall of the oil case 19 so as to sandwich the plate member 138 between the oil case 19 and the lid member 140. A second exhaust gas passage 141 isolated from the second cooling water passage 139 is formed. Moreover, the plate member 138 is formed of a material having elasticity, and is in close contact with the sealing surface 159 provided on the oil case 19 so as to surround the recess 137, thereby performing a sealing function.

The exhaust port 6 of the cylinder head 44
The exhaust gas discharged from the engine block 44
The exhaust gas flows into the exhaust expansion chamber 134 from the main exhaust gas passage 142 provided therein through the first exhaust gas passage 133, and is discharged into external water through a hollow portion around the propeller shaft 25.

On the other hand, a passage 143 for guiding a part of the exhaust gas from the upper part of the exhaust expansion chamber 134 to the second exhaust gas passage 141 side is provided in the oil case 19, and this passage 143 is formed in the second exhaust gas passage. It is communicated with the passage 141.

In FIG. 12, the second exhaust gas passage 141
Has an inflow chamber 144, an upper expansion chamber 145, and a lower expansion chamber 146 communicating with the passage 143. Each of the chambers 144, 145, 146 is defined by a wall 140a provided on the inner surface of the lid member 140. You. The inflow chamber 144 is formed at a lower portion in the lid member 140. The wall 140a is provided between the inflow chamber 144 and an upper expansion chamber 145 disposed above the inflow chamber 144. Are communicated through the flow grooves 147. Also, the upper expansion chamber 14
5 and a lower expansion chamber 146 disposed below the upper expansion chamber 145 are communicated with each other through flow grooves 148 provided in the wall 140a. Moreover, the lid member 140 is integrally provided with an exhaust pipe 150 that forms a discharge passage 149 that communicates with the upper part of the lower expansion chamber 146 and that projects rearward. Part of the exhaust gas guided to the passage 141 side flows through the second exhaust gas passage 141 as indicated by a broken line arrow in FIG.
The gas is discharged from the exhaust pipe 150 to the outside.

A return chamber 151 is formed in the lid member 140 below the inflow chamber 144. In addition, the wall 140a is provided with a return groove 152 for communicating the lower end in the lower expansion chamber 146 with the return chamber 151, and water separated from exhaust gas in the lower expansion chamber 146 and accumulated in the lower expansion chamber 146 is provided. It flows from the return groove 152 to the return chamber 151. Further, the return chamber 151 is provided in the oil case 19 in the exhaust expansion chamber 1.
A return passage 153 communicating with the exhaust gas is provided in the lower expansion chamber 146 and returned to the exhaust expansion chamber 134.

On the other hand, cooling water pumped by a cooling water pump (not shown) is supplied to a lower portion of the second cooling water passage 139 from a cooling water inlet 154 provided in the oil case 19 and is supplied to the second cooling water passage 139. And flows into a third cooling water passage 155 provided in the oil case 19 at a position above the cooling water inlet 154. At this time, the third cooling water passage 1 is connected to the third cooling water passage 154 in the second cooling water passage 139.
In order to prevent the cooling water from flowing directly toward 55, a baffle plate 156 for meandering the flow of the cooling water is provided in the oil case 19 as shown by the arrow in FIG. Thereby, the passage wall 132 constituting the first exhaust gas passage 133
The cooling water can be evenly circulated in the portion facing the second cooling water passage 139. Further, a communication groove 156a is provided at the lower end of the baffle plate 156, and when the cooling water pump is operating, a part of the cooling water from the cooling water inlet 154 is connected as shown by the arrow in FIG. Fifteen
6a flows upward from the second cooling water passage 139 into the second cooling water passage 139. When the cooling water pump is stopped, the cooling water can be returned from the second cooling water passage 139 to the cooling water inlet 154 via the communication groove 156a. And thereby the baffle 15
The accumulation of water on the upper side of 6 is avoided.

The cooling water flowing to the third cooling water passage 155 is
Water jacket 157 provided on engine block 43 and cylinder head 44 (see FIGS. 3 and 5)
The cooling water discharged from the water jacket 157 descends in the first cooling water passage 131 and flows down to the lower drive shaft chamber 135. The oil case 19 has a third
Water extraction pipe 158 leading to the middle of cooling water passage 155
Is attached.

Referring also to FIG. 13, the oil case 1
9 is provided with an insertion hole 161 having an outer end opened above the sealing surface 159 surrounding the concave portion 137 and an inner end opened to the first exhaust gas passage 133, so that exhaust gas for collecting exhaust gas is provided. An inner end of the gas sampling pipe 162 is inserted into the first exhaust gas passage 133 from the insertion hole 161. The exhaust gas sampling pipe 162 penetrates through the lid member 140 and is fixed to the lid member 140. The exhaust gas sampling pipe 162 is provided in a screw hole 163 provided in the lid member 140 corresponding to the insertion hole 161. The external thread portion 164 provided on the outer surface of the intermediate portion of the exhaust gas collecting pipe 162 is screwed together.
Is hermetically fixed to the lid member 140.

A part of the male screw portion 164 is formed by a cover member 140.
A cylindrical plug 165 having a bottom and covering the outer end of the exhaust gas sampling pipe 162 is screwed into the male screw portion 164 at a protruding portion from the lid member 140, and the plug 165 is closed. An engagement groove 166 for engaging a rotary tool such as a driver is provided on the outer end surface, and a washer 167 is sandwiched between the open end of the plug 165 and the outer surface of the lid member 140.

The plate member 138 has the insertion hole 161.
A through hole 168 corresponding to the outer end of the insertion hole 161 is provided, and the periphery of the outer end of the insertion hole 161 is sealed by the flat plate member 138.

Referring also to FIG. 14, the under cover 14 is a pair of synthetic resin cover halves 170 and 171 which are connected to each other by covering the lower half of the engine E and the upper part of the casing 16 from both sides. The fitting surface of one cover half 170 to the cover half 171 is provided with a fitting groove 170a, and the other cover half 171 is provided.
The fitting groove 170 a
Is provided with a fitting projection 171a.

As shown in FIG. 3, a notch 172 is provided at the upper end of the front portion of the under cover 14, and the support arm 19a provided in the oil case 19 is connected to the support arm 19a.
a is disposed in the notch 172 such that the front end of the “a” is exposed to the outside.

At the rear of the under cover 14,
In a portion corresponding to the exhaust pipe 150, a through hole 173 is provided to project a rear end of the exhaust pipe 150 so as to discharge exhaust gas from the exhaust passage 149 of the exhaust pipe 150 to the rear side of the under cover 14. .

The under cover 14 is fixed to the upper part of the casing 16. A pair of mounting bosses 19 b, 19 b projecting from the lower part of the rear outer wall of the oil case 19, which is the upper part of the casing 16, are attached to the two covers. The rear portions of the halves 170 and 171 are fastened with screw members 174 and 174, respectively. The front portions of the two cover halves 170 and 171 are fastened to the upper portion of the front portion of the oil case 19 with screw members 175. The front portions are fastened with screw members 176, respectively. That is, the under cover 14 is provided with the oil case 19 and the extension case 20 at the upper part of the casing 16.
Is fixed to the upper end.

At the center of the rear part of the head cover 45 constituting a part of the engine body 22, a support projection 4 projecting rearward is provided.
5b is protruded, and a metal fitting 177 having screw holes with both ends opened is embedded in the rear end of the support protrusion 45b. On the other hand, mounted portions 170b, 171b sandwiching the support projection 45b from both sides are integrally provided on the upper portions of the two cover halves 170, 171 constituting the under cover 14, and the mounted portions 170b, 171b are provided. Are fastened to the support projection 45b by screw members 178, 178 screwed to the metal fittings 177. That is, the upper part of the undercover 14 is a head cover 45 that is a part of the engine body 22.
, So that it is detachably fixed to the main body.

An inverted J-shaped arm 45c extending upward from the support protrusion 45b is integrally connected to the rear end of the support protrusion 45b, and the support protrusion 45b and the arm 45c are integrally provided.
Between them, an intermediate portion of a throttle cable 179 for operating the throttle valve 80 of the carburetor 74 is held.

The engine cover 13 is formed of a synthetic resin in the shape of a dish that covers the upper half of the engine E.
A hook 180 fixed to the engine cover 13 at the front of the outboard motor is engaged from the rear side into an engagement hole 181 provided at the front end of the support arm 19a in the oil case 19. A hook lever 182 is supported at the rear of the outboard motor above the undercover 14 so as to be rotatable about a horizontal axis. A hook 183 attached to the hook lever 182 is attached to the rear of the engine cover 13. It is engaged with a locking portion 184 provided. That is, the engine cover 13
The upper end of the under cover 14 is detachably connected to the lower end of the under cover 14.

On the rear side of the outboard motor, above the engine cover 13, a grip 13a for tilt-up operation is provided so as to be depressed forward, and an air introduction pipe 185 communicating with the inner end of the grip 13a is provided. Are provided integrally with the engine cover 13 to introduce air into the engine cover 13. In addition, the air introduction pipe 185 has a lower end opened and extends vertically just above the belt cover 60. In order to prevent water that has entered from the air introduction pipe 185 from scattering on the upper surface of the belt cover 60, the belt cover 185 is provided. 60
A dish-shaped portion 186 which is open upward so as to surround the lower end of the air introduction pipe 185 is integrally provided on the upper portion of the air inlet tube 185.

Next, the operation of this embodiment will be described. The upper part of the under cover 14 fixed to the upper part of the casing 16 is detachably fixed to the head cover 45 of the engine body 22, and the lower end of the engine cover 13 is Because it is detachably connected to the upper end of 14,
The upper part of the under cover 14 is firmly supported by the engine body 22, and the lower part of the engine cover 13 is firmly supported by the engine body 22 via the upper part of the under cover 14. Therefore, the engine cover 13
When the tilt-up operation is performed by gripping the grip portion 13a provided on the upper portion of the engine cover 13, deformation at the lower portion of the engine cover 13 and the upper portion of the under cover 14 can be suppressed to be small, and the rigidity of the engine cover 13 and the under cover 14 can be reduced. A feeling of sex can be obtained.

The head cover 45 of the engine E
The other end of the breather pipe 121 connected to the upper part of the head cover 45 in connection with the breather chamber 118 inside is connected to the intake silence box 75 of the intake device 73 arranged on one side of the engine block 43. But the camshaft 5
The breather pipe 121 is disposed along the outer surface of the belt cover 60 disposed above the cylinder head 44 so as to cover at least a portion corresponding to the driven pulley 58 of the belt transmission means 56 that connects between the cylinder shaft 4 and the crankshaft 23. The intermediate portion of the breather pipe 121 is fixed to the belt cover 60 by a fixing member 122. Therefore, the breather pipe 121 can be brought close to the belt cover 60 until it comes into contact with the belt cover 60, and can be piped so as not to protrude from the intake device 73 to the side. However, the breather pipe 121 is provided in the engine cover 13.
Can be piped compactly.

The carburetor 74 of the intake device 73 is of a variable venturi type, in particular, a so-called constant vacuum type utilizing a negative pressure. By changing the opening area, it is possible to achieve both low-speed and high-speed performances, increase the accuracy of the air-fuel ratio, reduce fuel consumption and improve exhaust properties.

Further, the bypass-type starter 77 is attached to the carburetor body 78 of the carburetor 74. Since the bypass-type starter 77 is attached to the carburetor body 78 between the intake passage 79 and the engine block 43. In addition, the bypass-type starter 77 does not protrude from the carburetor body 78 to the outside, and the engine cover 13 can be prevented from being enlarged in order to avoid interference with the bypass-type starter 77.

Further, air is introduced into an intake silence box 75 disposed at the upstream end of the intake device 73 in a direction substantially along the cylinder axis of the engine block 43 along the front-rear direction of the outboard motor, and the downstream end is vaporized. A first air passage 109 connected to the heater 74 and a first air passage
A second air passage 110 which is substantially perpendicular to the air flow direction in the air passage 109 and whose upstream end is open to the outside is formed, and is disposed on a plane substantially parallel to the air flow direction in the first air passage 109. Thus, the cleaner element 112 interposed between the upstream end of the first air passage 109 and the downstream end of the second air passage 110 is housed and fixed in the intake silence box 75.

Accordingly, the air is purified by the cleaner element 112 while the air flows from the second air passage 110 to the first air passage 109. In addition, the first air passage 109 allows air to flow in a direction substantially along the cylinder axis of the engine block 43, that is, in a substantially front-rear direction of the outboard motor.
Since it is arranged on a plane substantially parallel to the air flow direction in the air passage 109, the arrangement of the cleaner element 112 does not increase the size of the intake silencer 75 in the lateral direction of the outboard motor. Thus, the air purifying function can be provided while avoiding the size increase.

The direction of air flow at the downstream end of the second air passage 110 is set in the left-right direction of the outboard motor, and the cleaner element 1 is disposed on a plane substantially along the vertical direction of the outboard motor.
12 and the engine block 43, the second air passage 1
By arranging 10, the upstream end opening of the intake silence box 75 can be arranged at a position covered by the intake silence box 75 itself, and has penetrated into the engine cover 13 and the under cover 14 covering the engine E. Water is in the intake device 73
Inhalation into the inside can be prevented as much as possible.

By the way, a recess 137 is formed on the outer wall of the oil case 19 which integrally has a passage wall 132 forming a first exhaust gas passage 133 for leading the exhaust gas from the engine E.
A sealing surface 159 surrounding the concave portion 137 is provided, and a lid member 140 attached to the outer wall of the oil case 19 via a plate member 138 between the sealing surface 159 and the sealing surface 159.
7, a second cooling water passage 139 and a second exhaust gas passage 141 which are separated from the first exhaust gas passage 133 are formed. An exhaust gas sampling pipe 162 is inserted into the first exhaust gas passage 133 from the inserted insertion hole 161. Moreover, the plate member 138 that performs a sealing function is formed so as to surround the outer end opening of the insertion hole 161, and the exhaust gas sampling pipe 162 penetrates through the lid member 140 and is hermetically fixed to the lid member 140.

Accordingly, the cover member 140 only needs to have a space enough to penetrate the exhaust gas collecting pipe 162, and the exhaust gas collecting pipe 162 is inserted into the first exhaust gas passage 133 while avoiding an increase in the size of the cover member 140. The oil case 19 and the cover member 1 around the exhaust gas sampling pipe 162
It is possible to reliably seal the space between the forties.

Further, a part of the outer wall of the oil case 19 is constituted by the passage wall 132, and the recessed portion 1 provided on the outer wall of the oil case 19 so as to face a part of the passage wall 132.
37 is covered with the plate member 138 and the second cooling water passage 139 is formed between the plate member 138 and the concave portion 137.
32 can be effectively cooled to prevent an increase in the temperature of the oil pan 123 integrated with the passage wall 132, and there is no need to consider a draft angle due to molding for forming the second cooling water passage 137. In addition, the size and weight of the oil case 19 can be avoided.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible.

[0081]

As described above, according to the present invention, the breather pipe can be brought close to the belt cover until it comes into contact with the belt cover, and can be piped so as not to protrude laterally from the intake device. The pipe can be compactly piped.

[Brief description of the drawings]

FIG. 1 is an overall side view of an outboard motor.

FIG. 2 is an enlarged vertical sectional view of a main part of FIG.

FIG. 3 is a perspective view of FIG. 2 without an engine cover;
It is a 3 line expanded sectional view.

FIG. 4 is a side view of FIG. 2 with the engine cover omitted;
It is a 4-line enlarged sectional view.

FIG. 5 is an enlarged view of a main part of FIG. 2;

FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 4;

FIG. 7 is an enlarged sectional view taken along line 7-7 of FIG.

FIG. 8 is a sectional view taken along line 8-8 of FIG. 6;

FIG. 9 is a sectional view taken along line 9-9 of FIG. 6;

FIG. 10 is a cross-sectional view of the oil case, taken along the line 1 in FIG.
It is sectional drawing which follows the 0-10 line.

FIG. 11 is a rear view of the oil case as viewed from the direction of arrow 11 in FIG. 10;

FIG. 12 is a front view of a lid member attached to a rear surface of the oil case.

FIG. 13 is an enlarged vertical sectional view showing a mounting structure of the exhaust gas sampling pipe.

FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 2 for explaining a structure for fixing the lower end of the undercover to the casing.

[Explanation of symbols]

 13 ... Engine cover 23 ... Crankshaft 43 ... Engine block 44 ... Cylinder head 45 ... Head cover 46 ... Valve train chamber 54 ... Camshaft 55 ... Valve train 56 ... belt transmission means 58 ... driven pulley 59 ... timing belt 60 ... belt cover 73 ... intake device 118 ... breather chamber 121 ... breather tube E ... engine

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[Procedure amendment]

[Submission date] December 21, 2000 (200.12.
21)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (1)

[Claims] 1. A vertically extending crankshaft (23).
An engine block (43) rotatably supporting the cylinder block, a cylinder head (44) connected to the engine block (43), and a valve train chamber (46) formed between the cylinder head (44). A head cover (45) coupled to a cylinder head (44);
A valve mechanism (55) having a camshaft (54) having an axis parallel to 3) and housed in the valve chamber (46);
And a driven pulley (58) fixed to one end of the camshaft (54) above the cylinder head (44) and a timing belt (59) wound around the pulley (58). (54) and a belt transmission means (56) connecting between the crankshaft (23) and a belt cover (60) covering at least a portion corresponding to the driven pulley (58). In an outboard motor whose upper half is covered with an engine cover (13), a breather tube (12) extending along the outer surface of the belt cover (60) and having an intermediate portion fixed to the belt cover (60).
One end of 1) is connected to the upper part of the head cover (45) in connection with a breather chamber (118) formed in the head cover (45), and is connected to the engine block (4).
3) The breather pipe (12) is provided to an intake device (73) arranged on one side and connected to the cylinder head (44).
An outboard motor, wherein the other end of 1) is connected.