JP2000213354A - Engine and engine mounting outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower a temperature of an intake passage and enable to keep a temperature of a cylinder to an appropriate value, by forming an intake air cooling passage for cooling an intake passage of a cylinder head, and arranging a thermostat at the cylinder cooling passage instead of arranging it at an intake air cooling passage. SOLUTION: An engine of an outboard motor has a crankshaft 24 disposed in an approximately vertical direction, and a cylinder block 32 constituted of two cylinders 26 in upper and lower directions in the rear of the crankshaft 24. A cylinder head 36 is disposed to cover the cylinder block 32 on a side of a combustion chamber 34. A combustion chamber cooling communicating passage 36f, which communicates to a channel 117 around the combustion chamber 34 and an intake air cooling passage, and a channel 114 around a cylinder, which communicates to the channel 117, are formed to the cylinder head 36. A thermostat 119 is disposed to an upper end of the channel 114 around the cylinder, and is opened to flow cooling water to a discharge pipe when a cooling water temperature is more than or equal to a set temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine in which an intake passage for supplying air to a combustion chamber is formed in a cylinder head and an outboard motor equipped with the engine, and more particularly to a counterflow type engine.

[0002]

2. Description of the Related Art During normal operation of an engine, the intake passage and the cylinder of a cylinder head become relatively high in temperature due to the heat of a combustion chamber which becomes high in temperature. In particular, when the engine is of a counter flow type, an exhaust passage through which high-temperature exhaust gas flows is arranged close to the intake passage, and the temperature of the intake passage depends on the heat effect of the relatively high-temperature exhaust passage. It rises in response to it.

[0003]

If the temperature of the intake passage is too high, the temperature of the air supplied to the combustion chamber rises and the engine output decreases. In particular, when the engine is a counter flow type, the temperature of the intake passage interposed between the exhaust passages becomes higher than the temperature of the intake passage not interposed between the exhaust passages. Therefore, the output balance of the engine deteriorates. If the temperature of the cylinder is too low, the viscosity of the lubricating oil increases, and the reciprocation of the piston may not be performed smoothly. On the other hand, if the temperature of the cylinder is too high, overheating occurs, knocking or the like occurs, and the rotation of the engine becomes unstable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to keep the temperature of an intake passage low,
It is an object of the present invention to provide an engine capable of setting a cylinder temperature to an appropriate value as much as possible and an outboard motor equipped with the engine.

[0005]

According to the present invention, there is provided an engine (1).
3) is a cylinder (26) in which a piston (28) is slidably disposed, a cylinder block (32) in which the cylinder is formed, and a combustion chamber (3) of the cylinder.
4) a cylinder head (36) covering the side, an intake passage (41) formed in the cylinder head and supplying air to the combustion chamber, and a combustion chamber formed in the cylinder head. An exhaust passage (42) for exhausting exhaust gas from the cylinder, and a cylinder cooling passage (32f, 36f, 114, 117, 12) for cooling the cylinder.
, 122, 123) and intake cooling passages (32g, 36g, 131, 131) for cooling the intake passage of the cylinder head.
133). And the thermostat (1
19) is provided in the cylinder cooling passage, and is not provided in the intake cooling passage.

In some cases, the engine is of a counter flow type, and the intake passage and the exhaust passage are arranged on the same side of the combustion chamber.

Further, a plurality of cylinders are provided,
In some cases, the intake air cooling passage cools the intake passage located between the exhaust passages and hardly cools the intake passage not located between the exhaust passages.

In the outboard motor in which the engine is mounted on the guide exhaust (7), the cooling water flowing out of the cylinder cooling passage is discharged out of the outboard motor without passing through the guide exhaust. There are cases.

In an outboard motor in which the engine is mounted on a guide exhaust, an exhaust pipe (77) for guiding exhaust gas from the engine below the guide exhaust, and cooling water supplied from outside the outboard motor. Cooling water ascending flow path (23e, 93, 101, 111)
And an exhaust pipe cooling channel (7h, 78, 79) for cooling the exhaust pipe, and a cooling water upstream channel, a cylinder cooling channel, an intake cooling channel, and an exhaust pipe cooling channel. May be branched.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an engine and an outboard motor equipped with the engine according to the present invention will be described with reference to FIGS. FIG. 1 is a side view of an outboard motor according to an embodiment of the present invention. FIG. 2 is a sectional view of the outboard motor of FIG. FIG. 3 is an enlarged view of a main part of FIG. FIG. 4 is a partially cutaway sectional view of the upper part of the outboard motor as viewed from the right side. FIG.
FIG. 2 is a sectional view of a main part of the engine. FIG. 6 is a plan view of the inside of the outboard motor. FIG. 7 is a plan sectional view of the engine of the outboard motor. FIG. 8 is a sectional view of a main part of the outboard motor, and FIGS.
It is VIII sectional drawing of. FIG. 9 is a sectional view of a main part of the outboard motor, and is a sectional view taken along line IX of FIGS. FIG. 10 is a sectional view of a main part of the outboard motor, and is a sectional view taken along line XX of FIG. FIG. 11 is a front view of the cylinder head. FIG. 12 is a bottom view of the cylinder block and the crankcase. FIG. 13 is a plan view of the guide exhaust. 14A and 14B are bottom views of the guide exhaust and the exhaust pipe. FIG. 14A is a view of the guide exhaust, and FIG. 14B is a view of the exhaust pipe. 15A and 15B are plan views of the connection case and the exhaust pipe. FIG. 15A is a view of the connection case, and FIG. 15B is a view of the exhaust pipe. FIG. 16 is a perspective view of the exhaust pipe. FIG. 17 is an explanatory view of the intake passage cooling jacket, and is an enlarged view of a main part of FIG. In FIG. 5, the front part of the communication passage for cooling the combustion chamber and the distribution passage communicating with the communication passage for cooling the combustion chamber is not originally visible, but is shown by a solid line. In FIG. 8, the cylinder block is shown in a rear view, and the arrangement positions of the intake passage and the exhaust passage of the cylinder head, which are originally invisible, are shown by two-dot chain lines. In FIG. 9, the left side portion of the cylinder block is a cross-sectional view of a portion of the blister passage. Further, in FIG. 15A, the arrangement position of the exhaust pipe 77 is shown by a two-dot chain line. Also, in FIG. 17, the arrangement position of the intake passage cooling jacket is shown by a broken line. In this specification, the cylinder arrangement side is referred to as "rear side" and the starboard side is referred to as "right side" with respect to the crankshaft.

The outboard motor is attached and fixed to a transom 2 of a small boat by a mounting bracket 1. A pivot shaft 3 is rotatably provided at a rear portion of the mounting bracket 1. The pivot shaft 3 has an upper end portion on a guide exhaust 7 via an upper mount 6, and a lower end portion on a lower mount 9. And is connected to the upper casing 11 via. The upper end of the pivot shaft 3 projects forward, and a steering bracket 10 is formed. A steering wheel 12 is rotatably attached to the steering bracket 10. The steering wheel 12 has a use position protruding forward indicated by a solid line and a storage position indicated by a two-dot chain line in FIG. Can be turned between. The engine 13 is mounted on the guide exhaust 7 and is fixed with bolts or the like. The upper mount 6 includes a pair of left and right rods 6a fixed to the pivot shaft 3, a mounting tool 6c having a pair of left and right cylinder portions 6b into which the rods 6a are inserted, and a cylinder 6b and a rod 6a. And a rubber 6d as an elastic body interposed therebetween. On the upper surface of the attachment 6c of the upper mount 6, a groove 6e is formed between the left and right cylindrical portions 6b so as to extend in the front-rear direction.

The outside of the engine 13 is covered with an upper cowling 16 and a lower cowling 17. The lower cowling 17 is supported by the guide exhaust 7 and also supports the upper cowling 16. When the handle 12 is in the storage position,
It is located on the left side of cowlings 16 and 17. And
The connection case 21, the upper casing 11, and the lower casing 23 are sequentially connected to the lower side of the guide exhaust 7. In addition, the guide exhaust 7 and the connection case 21 are connected so that the left and right side surfaces are substantially flush with each other, and the outside of the guide exhaust 7 and the connection case 21 is not a structural member in order to improve the appearance. Apron 25 is covered. The apron 25 is detachably attached to the connection case 21 by appropriate means.

The engine 13, which is an internal combustion engine, has four L-cylinder cycles and has a counter flow type, that is, an intake passage and an exhaust passage are formed on the right side, that is, on the same side as the combustion chamber. This engine 13
The crankshaft 24 is provided with its axis substantially vertical, that is, in the vertical direction, and behind the crankshaft 24, two cylinders 26 are provided in the vertical direction. Two pistons 28 are connected to the crankshaft 24 via connecting rods 29, respectively. The pistons 28 are slidably disposed inside the cylinders 26. The case 31 of the engine 13 is provided with a cylinder block 3 forming the two cylinders 26 described above.
2, a crankcase 33 that covers the crankshaft 24 side of the cylinder block 32, and a cylinder head 36 that covers and closes the combustion chamber 34 side of the cylinder block 32. Cylinder block 3 of this engine 13
2 and the crankcase 33 are mounted and fixed on the upper surface of the guide exhaust 7. On the other hand, the cylinder head 36 is not in contact with the guide exhaust 7 and is not attached to the guide exhaust 7. With this configuration, the cylinder head 36 only needs to secure a high processing accuracy only on the front surface attached to the cylinder block 32 as compared with the case where the cylinder head 32 is attached to both the cylinder block 32 and the guide exhaust 7. Even if the processing accuracy of the lower surface is relatively low, problems are reduced, and processing and assembly are facilitated.

The lower end of the crankshaft 24 is
Drive shaft 38 protruding from engine case 31
It is connected to. The drive shaft 38 is disposed so as to extend vertically in the connection case 21, the upper casing 11, and the lower casing 23. The rotation of the drive shaft 38 is transmitted to a propeller 39 rotatably provided at the rear end of the lower casing 23 via a bevel gear (not shown) or the like.

The cylinder head 36 has a front end opening into the combustion chamber 34 to supply air to the cylinder 26, and similarly, a front end opening into the combustion chamber 34 and the combustion of the cylinder 26. An exhaust passage 42 for exhausting gas is formed for each cylinder 26, that is, for each cylinder. The ports of the intake passage 41 and the exhaust passage 42 are connected to the combustion chamber 34
And the intake passage 41
Are disposed above the ports of the exhaust passage 42. Each port is opened and closed by a valve 46. This valve 46
Is driven by a camshaft 48 via a rocker arm 47. This camshaft 48 extends in the up-down direction.

The upper end of the crankshaft 24 is
A drive pulley 51 protrudes from the engine case 31 and is fixed to an upper end portion of the crankshaft 24 with a nut. A flywheel 52 is mounted above the drive pulley 51. A driven pulley 54 is also provided at the upper end of the camshaft 48. Then, the timing belt 56 which is an endless transmission member is connected to the drive pulley 51 of the crankshaft 24,
The camshaft 48 is wound around the driven pulley 54, and the crankshaft 24 and the camshaft 48 rotate in conjunction with each other. On the lower side of the cylinder head 36,
An oil pump 57 is attached, and the oil pump 57 is driven by a cam shaft 48.

A rear end of an intake pipe 66 is connected to an end of each intake passage 41 of the cylinder head 36. The pair of upper and lower intake pipes 66 join and are connected to a carburetor 67.
8 are connected.

A combined exhaust passage 71 is formed in the cylinder block 32 so as to extend in the vertical direction, and two branch passages 72 branched from the combined exhaust passage 71 are provided in the cylinder head 36, respectively. It is connected to the exhaust passage 42. The lower end of the combined exhaust passage 71 of the cylinder block 32 is connected to the exhaust passage 7 formed in the guide exhaust 7.
6, and an exhaust pipe 77 is connected to the lower end of the exhaust passage 76 of the guide exhaust 7. A cooling water pipe 78 is formed integrally with the exhaust pipe 77, and a lower end of the cooling water pipe 78 extends below the exhaust pipe 77.
The upper end of the cooling water pipe 78 is connected to the guide exhaust 7
Is connected to the exhaust pipe cooling water channel 79.

The connection case 21 has an oil reservoir 81, an exhaust passage space 82, an idle expansion chamber 83, a front upper chamber 84, and a front lower chamber 86. Each space is separated from each other by a partition wall 87. The oil reservoir 81 has an open upper surface and the connecting case 2
One of the right and left side walls 21a and 21b is formed, and a strainer 88 is provided therein.
The strainer 88 is connected to a suction port of the oil pump 57 via a suction pipe 90 or the like. The exhaust passage space 82 is arranged on the rear side of the oil reservoir 81 and is formed to penetrate the connecting case 21 up and down. The exhaust pipe 7 is provided in the exhaust passage space 82.
7 are arranged. The idle expansion chamber 83 has an open upper surface and an exhaust port 89 formed in a rear wall. An idle exhaust groove 91 is formed between the exhaust passage space 82 and the idle expansion chamber 83 on the upper surface of the connection case 21. A front upper chamber 84 and a front lower chamber 86 as a drive shaft space and a cooling water rising space are vertically partitioned by a partition wall 87, and
The drive shaft 38 and the cooling water rising pipe 93 are vertically arranged through the partition 87. The front upper chamber 84 has an open front surface. On the other hand, the front lower chamber 8
Numeral 6 communicates with a front space 94 of the upper casing 11 and forms a water reservoir together with the front space 94.
A cooling water pump 96 is arranged in a front space 94 of the upper casing 11. This cooling water pump 96
Is driven to rotate by a drive shaft 38, and a discharge port thereof is connected to a cooling water rising pipe 93. The upper casing 11 has a front space 94.
On the rear side, an exhaust passage 102 is arranged with a partition wall interposed therebetween.

When the connecting case 21 configured as described above is attached to the lower surface of the guide exhaust 7, the guide exhaust 7 serves as an upper lid of the oil reservoir 81. An idle exhaust groove 92 is formed on the lower surface of the guide exhaust 7 at a position facing the idle exhaust groove 91 of the connection case 21. When the connecting case 21 is attached to the guide exhaust 7, an idle exhaust passage is formed by the idle exhaust grooves 91 and 92, and the exhaust gas in the exhaust passage space 82 is guided to the idle expansion chamber 83. ing. Further, a lower end of the guide exhaust 7 has a rear end projecting below the cylinder head 36 to form an overhang 7a. The overhang 7a is formed by the cylinder head 36 as described above.
Is not fixed, is cantilevered, and has low strength. In the connecting case 21, a part of the exhaust passage space 82 and the idle expansion chamber 83 are arranged below the overhang 7a of the guide exhaust 7, and the oil reservoir 81 is not arranged. That is, the rear end of the oil reservoir 81 is located forward of the cylinder head 36. Therefore, it is not necessary to support the oil reservoir 81 which contains the lubricating oil and becomes heavy by the overhang 7a, and the strength of the overhang 7a can be made relatively low. Therefore, the length of the oil reservoir 81 in the front-rear direction is shortened, and it is difficult to secure the volume of the oil reservoir 81. However, the oil reservoir 81 is formed over the left and right side walls 21a, 21b of the connection case 21. Therefore, the capacity can be increased as much as possible.

Next, a structure for supplying cooling water to the engine 13 will be described in detail. A cooling water intake 101 is formed in the lower casing 23. A suction water passage 23e is formed from the cooling water inlet 101 to the cooling water pump 96. The cooling water pump 96 is connected to the discharge port of the cooling water pump 96 as described above.
Extends upward, and the front space 9 of the upper casing 11
4. The distribution channel 1 extends through the front lower chamber 86 of the connection case 21 and the front upper chamber 84 of the connection case 21, and then extends rearward through the groove 6 e on the upper surface of the upper mount 6.
11 is connected. The distribution channel 111 includes a distribution groove 7 e on the upper surface of the guide exhaust 7 and a distribution groove 32 e on the lower surface of the cylinder block 32. When the cylinder block 32 is attached to the guide exhaust 7, the distribution groove 7e of the guide exhaust 7 and the distribution groove 32e of the cylinder block 32 are connected to face each other to form a distribution channel 111. these,
The cooling water inlet 101, the suction water passage 23e, the cooling water rising pipe 93, and the distribution flow path 111 constitute a cooling water rising flow path.

In the distribution groove 7e of the guide exhaust 7,
A water drop hole 7h communicating with the exhaust pipe cooling water channel 79 of the guide exhaust 7 is formed. And
An exhaust pipe cooling passage is constituted by the water drop hole 7h, the exhaust pipe cooling water passage 79, and the cooling water pipe 78. On the other hand, the distribution groove 3 of the cylinder block 32
A drain hole 113 is formed in 2 e and communicates with a cylinder surrounding flow path 114 formed around the cylinder 26 of the cylinder block 32. The rear surface of the cylinder surrounding flow path 114 is open. In the distribution groove 32e of the cylinder block 32, a communication passage 32f for cooling the combustion chamber and a communication passage 32g for cooling the intake / exhaust gas which extend rearward are formed. The cylinder head 36 has a combustion chamber cooling communication passage 36f and an intake / exhaust cooling communication passage 36f.
The combustion chamber cooling communication passage 36f and the intake / exhaust cooling communication passage 36g are connected to the combustion chamber cooling communication passage 32f and the intake / exhaust cooling communication passage 32g of the cylinder block 32, respectively. .

The communication passage 36f for cooling the combustion chamber of the cylinder head 36 communicates with a flow path 117 around the combustion chamber formed around the combustion chamber 34 of the cylinder head 36. The combustion chamber surrounding flow path 117 of the cylinder head 36 has an open front surface, and is connected to the rear opening of the cylinder surrounding flow path 114 of the cylinder block 32. A thermostat 119 is provided at the upper end of the cylinder surrounding flow path 114.
Is provided. A first drain pipe 121 is connected to the thermostat 119, and when the cooling water temperature is equal to or lower than a set temperature (for example, 60 ° C.), the flow from the cylinder surrounding flow path 114 to the first drain pipe 121 is substantially blocked,
On the other hand, when the cooling water temperature exceeds the set temperature, the flow from the cylinder surrounding flow path 114 to the first drain pipe 121 is permitted. The first drain pipe 121 is connected to a drain channel 122 provided in the cylinder block 32, and the drain channel 122 is connected to a second drain pipe 123. This second drainage pipe 123 is disposed below through between the guide exhaust 7 and the apron 25. The combustion chamber cooling communication passage 32f, the combustion chamber cooling communication passage 36f, the combustion chamber surrounding passage 117, the cylinder surrounding passage 114, the first drain pipe 121, and the drain passage 1
The 22 and the second drain pipe 123 constitute a cylinder cooling passage.

On the other hand, an intake / exhaust cooling communication passage 36 g of the cylinder head 36 is connected to an intake passage cooling jacket 131. In a side view (that is, when viewed from the outside), the intake passage cooling jacket 131 overlaps the lower intake passage 41 and both exhaust passages 42 of the cylinder head 36 (in other words, the intake passage 41 and the exhaust passage 42). It is placed in a state where it covers the outside and is cooled. And it does not overlap with the upper intake passage 41 and is hardly cooled. In addition, the intake passage cooling jacket 131
Is connected to a pilot water pipe 133.
The intake and exhaust cooling communication passage 32g, the intake and exhaust cooling communication passage 36g, the intake passage cooling jacket 131, and the pilot water pipe 133 constitute an intake cooling passage.

In the outboard motor configured as described above,
When the crankshaft 24 rotates, air is sucked into the carburetor 67 from the air suction portion 68, and fuel is supplied by the carburetor 67 to become a fuel mixture gas.
This mixed gas is supplied to the intake pipe 66 and the cylinder head 36.
, And flows into the combustion chamber 34 of the cylinder 26. The fuel gas mixture flowing into the combustion chamber 34 is ignited by an unillustrated spark plug and burned.
The exhaust gas generated at this time is discharged into the exhaust passage 42 of the cylinder head 36, the branch passage 72 of the cylinder block 32, the combined exhaust passage 71, the exhaust passage 76 of the guide exhaust 7, the exhaust pipe 77, and the exhaust passage space 82 of the connection case 21. And the exhaust passage 102 of the upper casing 11
Through the boss of the propeller 39 and the like. During idling, the exhaust gas of the connection case 21 passes through the idle exhaust grooves 91 and 92 between the guide exhaust 7 and the connection case 21 and passes through the idle expansion chamber 83.
And is discharged from the exhaust port 89. Then, due to the expansion force when the fuel gas mixture is burned, the piston 28
Reciprocates, and the reciprocating motion of the piston 28 causes the crankshaft 24 to rotate via the connecting rod 29.

As the crankshaft 24 rotates, the camshaft 48 rotates via the driving pulley 51, the timing belt 56, and the driven pulley 54, and the oil pump 57 operates. By the operation of the oil pump 57, the lubricating oil in the oil reservoir 81 of the connection case 21 is sucked into the oil pump 57 via the strainer 88 and the suction pipe 90, and is supplied to the engine 13. The procedure returns to the storage section 81. Also,
The gas in the oil reservoir 81 can flow to the cam chamber 108 in which the camshaft 48 is disposed, through the blister passage 106 of the guide exhaust 7, the blister passage 107 of the cylinder block 32, and the like.

The cooling water pump 96 operates with the rotation of the crankshaft 24. Cooling water pump 96
Supplies water outside the outboard motor from a cooling water intake port 101 formed in the lower casing 23 and supplies the water to a distribution flow path 111 via a cooling water rising pipe 93 or the like. In the distribution channel 111, the air is distributed to the cylinder cooling channel, the intake cooling channel, and the exhaust pipe cooling channel. That is, a part of the cooling water is supplied to the combustion chamber cooling communication passage 32f, the combustion chamber cooling communication passage 36f, the combustion chamber surrounding passage 117, the cylinder surrounding passage 114, the thermostat 119, the first drain pipe 121, the drain passage. The water is discharged through the drainage pipe 122 and the second drainage pipe 123 and flows out of the outboard motor through the gap between the apron 25 and the upper casing 11. When flowing through the combustion chamber surrounding flow channel 117 and the cylinder surrounding flow channel 114, the combustion chamber 34
And the cylinder 26 is cooled. Another part of the cooling water flows through the intake / exhaust cooling communication passage 32g, the intake / exhaust cooling communication passage 36g, the intake passage cooling jacket 131, and the pilot water pipe 133, and the cylinder head 36
After being cooled, the exhaust passage 42 and the intake passage 41 sandwiched between the exhaust passages 42 are discharged to the outside of the outboard motor. Further, the remaining part of the cooling water is supplied to the water drop hole 7h, the cooling water passage 79 for the exhaust pipe, and the cooling water pipe 7
8, the exhaust pipe 77 is cooled. The cooling water flowing out of the cooling water pipe 78 is discharged from the boss of the propeller 39 through the exhaust passage space 82 of the connection case 21 and the exhaust passage 102 of the upper casing 11. Also, the cooling water pipe 78
Is located below the exhaust pipe 77, the cooling water flowing out of the cooling water pipe 78 is
The flow into the engine 13 through the exhaust pipe 77 can be prevented as much as possible.

Further, the cooling water pump 96 discharges the cooling water to the cooling water rising pipe 93, and the cooling water pump 96
The cooling water leaks from the housing and supplies the cooling water to the front space 94 as a water reservoir of the upper casing 11. The front space 94 of the upper casing 11 communicates with a front lower chamber 86 serving as a water reservoir of the connection case 21. The front lower chamber 86 is also filled with cooling water, and the cooling water fills a lower part of the oil reservoir 81. Can be cooled. A hole through which the drive shaft 38 and the cooling water rising pipe 93 penetrate is formed in the partition wall 87 partitioning the front lower chamber 86 and the front upper chamber 84, and the front lower chamber 86 passes through the hole. Of cooling water flows into the front upper chamber 84. Since the front upper chamber 84 is open to the outside, the cooling water in the front upper chamber 84 is discharged to the outside from this opening.

As described above, in the embodiment, the cylinder cooling passage, the intake cooling passage, and the exhaust pipe cooling passage are branched from the cooling water upstream passage. Further, a thermostat 119 is provided in the cylinder cooling flow path, and when the engine is idling, the cylinder 26 is closed.
Can be prevented from being excessively cooled. Further, the intake passage 41 of the cylinder head 36 can be strongly cooled by the intake cooling passage. In particular, the intake passage 41 sandwiched between the exhaust passages 42 is different from the other intake passages 4.
The temperature tends to rise more than 1. However, the intake air cooling passage is provided closer to the intake passage 41 that is interposed between the exhaust passages 42 than the other intake passages 41, so that the temperature of the intake passage 41 is prevented from rising. Can be. As a result, the temperature difference between the intake passages 41 can be minimized.

Further, no thermostat is provided in the intake air cooling passage, and the cooling water from the cooling water pump 96 is
It can always flow through the intake cooling passage. Therefore, a large load can be prevented from being applied to the cooling water pump 96 as much as possible without providing a pressure valve. Further, cooling water having a relatively low temperature in the cooling water ascending flow path is also supplied to the exhaust pipe cooling flow path, so that the exhaust pipe 77 can be strongly cooled.

The engine 13 is of a counter flow type, and the intake passage 41 and the exhaust passage 42
Since it is arranged on the right side which is one side, a relatively large space can be secured on the left side which is the other side. As a result, arrangement of other parts such as auxiliary equipment becomes easy.

The cooling jacket 131 for the intake passage is
The exhaust passage 42 and the intake passage 41 located between the exhaust passages 42 are arranged so as to overlap with each other when viewed from the outside, and are arranged so as to overlap with the intake passage 41 not located between the exhaust passages 42. Absent. Therefore, the intake passage cooling jacket 131 is connected to the exhaust passage 4 which is likely to be high in temperature.
The intake passage 41 located between the two can be cooled. As a result, the temperatures of the intake passages can be made as equal as possible.

Further, the drainage passage of the cylinder cooling passage is drained out of the outboard motor without passing through the guide exhaust 7. Therefore, it is not necessary to form a drain passage in the guide exhaust 7, so that the structure is simplified, and the manufacturing cost and the material cost can be reduced. The drainage passage passes between the guide exhaust 7 and the apron 25, and is covered with the apron 25 to have a good appearance.

The handle 12 is disposed on the left side in the retracted state, and the intake passage 41 and the exhaust passage 42 are disposed on the right side. That is, the handle 12, the intake passage 41 and the exhaust passage 42 are disposed so as to be divided right and left around the cylinder 26. When the outboard motor is placed on the ground or the like, the handle 12 is placed on the lower side, so that the intake passage 41 and the exhaust passage 42 are located on the upper side.
Fuel and lubricating oil can be prevented from accumulating in the intake passage 41 and the exhaust passage 42.

Further, a remote control cable (not shown) for operating the carburetor 67 and the like is provided on the starboard side of the small boat to which the outboard motor is attached, and when the carburetor 67 is provided on the right side, Routing of the remote control cable becomes easy.

The embodiment of the present invention has been described above in detail.
The present invention is not limited to the above embodiment,
Within the gist of the present invention described in the claims,
Various changes can be made. Modification examples of the present invention are exemplified below. (1) In the above embodiment, the engine 13 is an L-type two-cylinder four-stroke engine, but the number of cylinders, the arrangement of the cylinders, and the like can be changed as appropriate. For example, it is also possible to use three cylinders or six cylinders. And
It is also possible to use a cross-flow type engine. However, in order to efficiently arrange components and the like, it is preferable to use a counter flow type. In addition, the engine can be employed for other than the outboard motor. (2) The relationship of the arrangement in the left-right direction can be reversed. (3) The number and arrangement of the cooling water pipes 78 can be changed as appropriate. For example, it is also possible to provide two.

[0037]

According to the present invention, a thermostat is provided in the cylinder cooling passage for cooling the cylinder to prevent the cylinder from being excessively cooled. On the other hand, no thermostat is provided in the intake cooling passage for cooling the intake passage of the cylinder head, and the intake passage can be cooled strongly.

When the engine is of a counter flow type and the intake passage and the exhaust passage are arranged on the same side with respect to the combustion chamber, the intake passage is arranged close to the relatively high-temperature exhaust passage. Although the temperature of the intake passage rises, the temperature of the intake passage can be prevented from rising as much as possible by the intake cooling passage. In addition, a relatively large space can be secured on the side where the intake passage and the exhaust passage are not arranged, and other parts such as auxiliary equipment can be easily arranged.

Further, a plurality of cylinders are provided,
In some cases, the intake air cooling passage cools the intake passage located between the exhaust passages and hardly cools the intake passage not located between the exhaust passages. The intake passage located between the exhaust passages is more susceptible to the heat of the exhaust passage than the intake passage not located between the exhaust passages, and the temperature balance between the intake passages is deteriorated. Thus, the temperature difference between the intake passages can be minimized.

In an outboard motor in which the engine is mounted on a guide exhaust, there is a case where cooling water flowing out of a cylinder cooling passage is discharged outside the outboard motor without passing through the guide exhaust. . In such a case, it is not necessary to provide a drainage passage in the guide exhaust, and the structure of the guide exhaust is simplified. As a result, the processing cost and material cost of the guide exhaust can be reduced.

Also, in the outboard motor in which the engine is mounted on a guide exhaust, an exhaust pipe for guiding exhaust gas from the engine below the guide exhaust, and a cooling system in which cooling water is supplied from outside the outboard motor. A water upflow path and an exhaust pipe cooling flow path for cooling the exhaust pipe are provided, and a cylinder cooling flow path, an intake cooling flow path, and an exhaust pipe cooling flow path are branched from the cooling water upflow path. May be. In such a case, cooling water having a relatively low temperature can be supplied to each of the cylinder cooling passage, the intake cooling passage, and the exhaust pipe cooling passage. Therefore, the temperature of the cylinder can be controlled by the thermostat, and the intake passage and the exhaust pipe can be efficiently cooled.

[Brief description of the drawings]

FIG. 1 is a side view of an outboard motor according to an embodiment of the present invention.

FIG. 2 is a sectional view of the outboard motor of FIG. 1;

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a partially cutaway sectional view of the upper part of the outboard motor as viewed from the right side.

FIG. 5 is a sectional view of a main part of the engine.

FIG. 6 is a plan view of the inside of the outboard motor.

FIG. 7 is a plan sectional view of the engine of the outboard motor.

FIG. 8 is a sectional view of a main part of the outboard motor, and is a sectional view taken along the line VIII of FIGS. 14 and 15;

FIG. 9 is a sectional view of a main part of the outboard motor, and is a sectional view taken along line IX of FIGS. 14 and 15;

FIG. 10 is a sectional view of a main part of the outboard motor,
It is -X sectional drawing.

FIG. 11 is a front view of a cylinder head.

FIG. 12 is a bottom view of a cylinder block and a crankcase.

FIG. 13 is a plan view of a guide exhaust.

14 is a bottom view of the guide exhaust and the exhaust pipe, where (a) is a view of the guide exhaust and (b) is a view of the exhaust pipe. FIG.

FIGS. 15A and 15B are plan views of the connection case and the exhaust pipe. FIG. 15A is a view of the connection case, and FIG. 15B is a view of the exhaust pipe.

FIG. 16 is a perspective view of an exhaust pipe.

FIG. 17 is an explanatory view of an intake passage cooling jacket, and is an enlarged view of a main part of FIG. 4;

[Explanation of symbols]

7 Guide exhaust 7h Guide exhaust exhaust hole (exhaust pipe cooling passage) 13 Engine 23e Suction water passage of lower casing (cooling water upflow passage) 26 Cylinder 28 Piston 32 Cylinder block 32f Combustion chamber cooling passage of cylinder block 32g Combustion chamber 36 Cylinder head 36f Combustion chamber cooling communication path (cylinder cooling passage) 36g Cylinder head intake / exhaust cooling Communication passage (intake cooling passage) 41 Intake passage of cylinder head 42 Exhaust passage of cylinder head 77 Exhaust pipe 78 Cooling water pipe (exhaust pipe cooling passage) 79 Cooling water passage for exhaust pipe of guide exhaust (exhaust pipe) 93 Cooling water upflow pipe (cooling water upflow path) 101 Cooling water intake port (cooling water upflow path) 111 Distribution flow path (cooling water upflow path) 114 Flow path around cylinder (cylinder cooling flow path) 117) Flow path around combustion chamber (cylinder cooling flow path) 119 Thermostat 121 First drain pipe (cylinder cooling flow path) 122 Drain flow path of cylinder block (cylinder cooling flow path) 123 Second drain pipe (cylinder cooling flow path) 131 Intake passage cooling jacket (intake cooling passage) 133 Pilot water pipe (intake cooling passage)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01P 3/02 F02B 61/04 3/12 67/00 E 11/04 G F02B 61/04 R 67/00 F02F 1/36 CB63H 21/26 DE F02F 1/36 A F term (reference) 3G004 AA05 DA23 EA06 3G024 AA09 AA11 CA05 CA26 DA03 DA04 DA09 DA17 DA23 EA11 FA14

Claims (5)

[Claims] 1. A cylinder in which a piston is slidably disposed, a cylinder block in which the cylinder is formed, a cylinder head covering a combustion chamber side of the cylinder, and a cylinder head formed in the cylinder head. An intake passage for supplying air to the combustion chamber; an exhaust passage formed in the cylinder head for exhausting exhaust gas from the combustion chamber; a cylinder cooling passage for cooling the cylinder; and the cylinder head. And an intake cooling passage for cooling the intake passage, and a thermostat is provided in the cylinder cooling passage and not provided in the intake cooling passage. 2. The engine according to claim 1, wherein the intake passage and the exhaust passage are of a counter flow type arranged on the same side with respect to a combustion chamber. 3. A plurality of cylinders are provided, and the intake air cooling passage cools intake passages located between exhaust passages and almost cools intake passages not located between exhaust passages. 3. The engine according to claim 2, wherein the engine is not operated. 4. An outboard motor in which the engine according to claim 1, 2 or 3 is mounted on a guide exhaust, wherein the cooling water flowing out of the cylinder cooling passage does not pass through the guide exhaust, An outboard motor, which is discharged outside the outboard motor. 5. An outboard motor in which the engine according to claim 1, 2 or 3 is mounted on a guide exhaust, an exhaust pipe for guiding exhaust gas from the engine below the guide exhaust, and an outboard motor. A cooling water ascending flow path to which cooling water is supplied from the outside, and an exhaust pipe cooling flow path for cooling an exhaust pipe. The cooling water ascending flow path includes a cylinder cooling flow path, an intake cooling flow path, and an exhaust flow path. An outboard motor, wherein a pipe cooling passage is branched.