JPH09273424A - Engine for outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of heat in an exhaust passage on a cylinder. SOLUTION: A cylinder block 20 in an engine for an outboard motor is provided with an exhaust passage 79 for discharging combustion gas and a cylinder cooling water passage 91 for cooling a cylinder 11. A heat insulating space 95 is formed between the exhaust passage 79 and the cylinder cooling water passage 91.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a motor boat,
The present invention relates to an outboard motor engine that is mounted on a small boat such as a yacht or a fishing boat.

[0002]

2. Description of the Related Art Conventionally, in an outboard motor, the cylinder of the engine is cooled by water taken from the outside of the outboard motor, namely, cooling water. Further, the high temperature combustion gas discharged from the engine is discharged to the outside of the outboard motor through the exhaust passage.

[0003]

The outboard motor is required to be miniaturized as much as possible, and the cooling water passage through which the cooling water flows and the above-mentioned exhaust passage may be arranged close to each other. is there. As described above, when the exhaust passage is close to the cooling water passage, the heat of the exhaust passage heats the cooling water passage and the cylinder, and exerts a thermal influence.

Due to this heat effect, the cylinder may not be cooled to a predetermined temperature, and the engine may not exhibit the desired performance. In addition, the temperature distribution in the cylinder block of the engine becomes uneven, and the shape of the cylinder is slightly distorted and deformed.

By the way, in an engine, especially a four-cycle engine, when the cylinder is deformed, the piston arranged in the cylinder cannot slide smoothly, seizure occurs, the consumption of lubricating oil and blow-by gas are increased. The occurrence of

Further, if the temperature distribution in the cylinder block of the engine is non-uniform, atomization becomes non-uniform in an engine of a type in which fuel is injected by a fuel injection pump, which adversely affects the performance.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an outboard motor engine in which the heat of the exhaust passage hardly affects the cylinder.

[0008]

In order to achieve the above object, the engine (7) of the outboard motor of the present invention comprises an exhaust passage (79) for exhausting combustion gas and a cylinder (1).
A cylinder cooling water passage (91) for cooling 1) is provided in the cylinder block (20) of the engine, and a heat insulating space (95) is formed between the exhaust passage and the cylinder cooling water passage. ing.

In addition, the heat insulating space may be provided inside the cylinder block and may be provided with an opening portion open to the outside of the cylinder block.

Further, the cylinders of the engine are arranged in the cylinder block so as to be distributed in the left-right direction so as to form a V-shape, and the cylinder block is provided with a cylinder cooling water passage for cooling the cylinder. The left side cylinder head (22a) may be closed on the combustion chamber (11a) side of the left cylinder, while the right side cylinder chamber side may be closed by the right side cylinder head. The exhaust passage for exhausting combustion gas of the engine includes a cylinder head exhaust passage (32) provided in each of the left and right cylinder heads and a cylinder block exhaust passage provided in a cylinder block of the engine. There is. The cylinder block exhaust passage communicates with the left and right cylinder head exhaust passages and is arranged between the cylinders that are adjacent to each other in the V-shape on the left and right. A heat insulating space is formed between the cylinder block exhaust passage and the cylinder cooling water passage.

A left cylinder cooling water passage for cooling the left cylinder and a right cylinder cooling water passage for cooling the right cylinder are provided, and a cylinder block exhaust passage and a right cylinder cooling water passage are provided. In some cases, a heat insulating space on the right side is formed between the cylinder block exhaust passage and the cylinder cooling water passage on the left side. The right heat insulating space and the left heat insulating space communicate with each other at a communication portion (95b), and the upper end of this communication portion is open to the outside of the cylinder block.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of an engine of an outboard motor according to the present invention will be described with reference to FIGS. FIG. 1 is a partially cutaway sectional view of an outboard motor according to the present invention. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is an explanatory diagram for explaining the heat insulating space. FIG. 4 is a plan view showing the internal structure of the outboard motor of FIG. FIG. 5 is a cross-sectional view for explaining the internal structure of the outboard motor of FIG. FIG. 6 is an enlarged cross-sectional view of the main part of FIG. FIG. 7 is an explanatory diagram for explaining the throttle valve and the surge tank. FIG. 8 is a circuit diagram of the cooling water channel.

First, the overall structure of the outboard motor will be described. In FIG. 1, the outboard motor is covered with a housing including an upper cowling 1, a lower cowling 2, an upper casing 3 and a lower casing 4 in order from the upper side. A mounting bracket 6 is provided on the guide exhaust 23 and the upper casing 3 inside the lower cowling 2 via the swivel shaft 5 and the like. By fixing the mounting bracket 6 to the stern of a small boat such as a motor boat (not shown), the outboard motor is attached to the small boat so as to be rotatable in the left-right direction and the vertical direction.

In FIGS. 1, 4 and 5, the upper cowling 1 and the lower cowling 2 have a V inside.
A 6-cylinder 4-cycle engine 7 is arranged. The crankshaft 8 of the engine 7 is provided with its axis substantially vertical, and a pair of left and right cylinders 11 are arranged behind the crankshaft 8 so as to be laterally V-shaped. This pair of left and right cylinders 11
Are provided in three stages in the vertical direction, and the cylinders 11 are arranged in a total of six cylinders. Further, six pistons 13 are connected to the crankshaft 8 via connecting rods 14, respectively, and the pistons 13 are slidably arranged inside the cylinders 11. Also, the case 1 of the engine 7
Reference numeral 7 denotes a cylinder block 20 forming the above-described six cylinders 11, a crankcase 21 covering the crankshaft 8 side of the cylinder block 20, and a pair of left and right cylinders covering and closing the combustion chamber 11a side of the cylinder block 20. It is composed of a head 22. The engine case 17 is fixed to the upper surface of the upper casing 3 via the guide exhaust 23.

The lower end of the crankshaft 8 projects from the engine case 17 and extends, and the drive shaft 26 is disposed in the upper casing 3.
It is connected to. A water pump 27 is provided in the middle of the drive shaft 26. The rotation of the drive shaft 26 is transmitted to a propeller 28 rotatably provided at the rear end of the lower casing 4 via a bevel gear (not shown).

The cylinder head 22 is provided with an intake passage 31 for supplying air to the cylinder 11 and a cylinder head exhaust passage 32 for exhausting combustion gas of the cylinder 11 for each cylinder 11. The intake valve 35 is connected to the port of the intake passage 31, and the cylinder head exhaust passage 3
The exhaust valve 36 opens and closes the second port. The intake valve 35 is driven by an intake valve camshaft 38, and the exhaust valve 36 is driven by an exhaust valve camshaft 39. The intake valve camshaft 38 and the exhaust valve camshaft 39 are provided on the right cylinder head 22 and the left cylinder head 22, respectively, and extend in the up-down direction to form a single camshaft 38, 39. 3 valves 3
5, 36 can be controlled. The crankshaft 8 drives the camshafts 38 and 39 via a timing belt 48 or the like.

Next, the flow of air sucked and exhausted by the engine 7 will be described. In FIGS. 1, 5 and 7, the air outside the outboard motor flows in through an air intake port 61 provided on the upper side surface of the upper cowling 1 and is formed on the upper surface of the flywheel cover 62. The air intake pipe 66 of the engine 7 is reached through the passage 63. The air that has flowed into the air intake pipe 66 is throttle valve 67.
, Branch left and right as shown in FIG. 7,
Each flows into the surge tank 69. This surge tank 6
Three branch pipes 71 are formed in each of the pipes 9, and the ends of the branch pipes 71 are connected to the intake passage 31 via an intake manifold 73. Intake manifold 73
An injector 74 is attached to the.

The injector 74 is supplied with fuel from a fuel tank mounted on a small boat (not shown) through a vapor separator tank 76, and the timing and amount of supply of this fuel are controlled by a control unit ( (Not shown).

The air in the intake passage 31 mixed with the fuel flows into the cylinder 11 and burns when the intake valve 35 opens, as is well known in the art. The combustion gas is exhausted to the cylinder head exhaust passage 32 when the exhaust valve 36 is opened. This cylinder head exhaust passage 32 is provided in each of the left and right cylinder heads 22 by three.
Although individually formed, the ends of the cylinder head exhaust passage 32 are all connected to the cylinder block exhaust passage 79 formed in the cylinder block 20. The cylinder block exhaust passage 79 is formed between the left and right cylinders 11 arranged adjacent to each other in a V shape, extends in the cylinder block 20 in the vertical direction, and has an upper end closed. The lower end is open. Therefore, the combustion gas burned in each cylinder 11 joins in the cylinder block exhaust passage 79, passes through the exhaust passage 81 of the guide exhaust 23 connected to the cylinder block exhaust passage 79, and is connected to this exhaust passage 81. It flows through the exhaust pipe 83 and flows into the muffler 84. The combustion gas flowing into the muffler 84 is discharged from the shaft of the propeller 28 through a passage (not shown).

This muffler 84 is an upper casing 3
However, a space is formed between it and the upper casing 3, and this space serves as a water reservoir 86. Further, the upper end of the muffler 84 is configured to be liquid-tight with the oil pan 51 that is provided so as to hang down from the lower surface of the guide exhaust 23, and the upper end of the water sump 86 is located on the outer periphery of the side wall of the oil pan 51. Has reached Moreover, the inside of the muffler 84 has an exhaust passage 87 through which combustion gas passes,
It is divided into a drainage channel 88 through which water flows. Further, a water passage 89 communicating with the drainage passage 88 of the muffler 84 is formed in the oil pan 51, and an overflow opening 90 is formed in the side wall of the oil pan 51 so that the water reservoir 8
The water overflowing from 6 passes through the overflow opening 90,
It is configured to flow into the water channel 89.

Next, the cooling water passage will be described with reference to FIGS. 2 to 4, 6 and 8. Note that FIG. 8 shows the cylinder block 20 in the center, and shows the left and right cylinder heads 2
2 is removed from the cylinder block 20 and is arranged on the left and right sides of the cylinder block 20, and for the sake of clarity, the respective flow paths are connected.

In the cylinder block 20 of the engine 7,
To cool the cylinder 11, a cylinder cooling water passage 91, a connection cooling water passage 93, and a return cooling water passage 94 that are provided around the cylinder 11 are provided. The cylinder cooling water passage 91 is provided in each of the left and right cylinders 11, and extends in the up-down direction along the periphery of the three cylinders 11 arranged in the up-down direction. Is cooling three cylinders 11. Further, the connection cooling water passage 93 is arranged to extend vertically on the crankshaft 8 side of the cylinder block exhaust passage 79. Then, the return cooling water passage 94
Are provided at corners on the crankshaft 8 side between the pair of left and right cylinders 11 arranged in a V shape.

Further, the cylinder block 20 has a structure shown in FIG.
A space 95 for heat insulation shown with dots is provided. The heat insulating space 95 is shown in FIG.
In the cylinder block exhaust passage 79, the connection cooling water passage 93 and the return cooling water passage 94,
And the cooling water passage 91 for the cylinder.
Is located on the cylinder block exhaust passage 79 side. Therefore, the heat insulating space 95 is formed between the cylinder block exhaust passage 79 and the cylinder cooling water passage 91 so that the heat of the cylinder block exhaust passage 79 is not transferred to the cylinder cooling water passage 91 and the cylinder 11. . The heat insulating space 95 is provided on the right and left sides of the cylinder block exhaust passage 79, and the left and right heat insulating spaces 95 are connected to each other to form a substantially V shape. V-shaped both ends 95a of the space 95 for heat insulation
And the corner portions 95b extend in the vertical direction, and both end portions 9b
The upper and lower ends of 5a and the upper ends of corners 95b are open to the outside. Further, the lower end of a corner portion 95b, which is a communication portion between the left heat insulating space 95 and the right heat insulating space 95, is closed. The portion between the end portion 95a and the corner portion 95b is divided and formed for each cylinder 11. That is, in FIG. 3, three stages are provided vertically.

On the other hand, each of the pair of left and right cylinder heads 22 has a cooling water passage 101 for a cylinder head exhaust passage for cooling the cylinder head exhaust passage 32 and a cooling water passage 103 for a combustion chamber for cooling the combustion chamber 11a. Has been formed. The three cylinder head exhaust passage cooling water passages 101 are arranged in the vertical direction.
Is formed so as to extend in the vertical direction along the outer surface of the. Further, the combustion chamber cooling water passage 103 extends in the up-down direction along the periphery of the combustion chamber 11a.

When the cylinder head 22 and the cylinder block 20 are connected to each other, the upper end of the connecting cooling water passage 93 is, as shown in FIGS.
It communicates with the upper end of the cooling water passage 101 for the cylinder head exhaust passage. Further, as shown in FIGS. 6 and 8,
The cylinder cooling water passage 91 and the combustion chamber cooling water passage 103 communicate with each other at both upper and lower ends and in the middle. Further, as shown in FIGS. 2 and 8, the lower end of the connection cooling water passage 93 and the lower ends of the cylinder cooling water passage 91 and the combustion chamber cooling water passage 103 are connected to each other by a communication passage 106 formed in the guide exhaust 23. Are connected via.

When the crankshaft 8 rotates, the drive shaft 26 also rotates and the water pump 27 operates. Then, the water outside the outboard motor is sucked from the water intake 108 (see FIG. 8) formed in the lower casing 4, and the water is supplied from the water pump 27 to the cooling water passage 101 for the cylinder head exhaust passage through the water tube 111 and the like. It flows in and cools the cylinder head exhaust passage 32. At the upper end which is the terminal end of the cylinder head exhaust passage cooling water passage 101,
The pressure valve 114 is provided, and when the pressure of the cooling water is higher than the predetermined pressure, the pressure valve 114 is opened, and the cooling water is supplied to the pressure valve 11.
4 to the return cooling water passage 94.

On the other hand, when the pressure of the cooling water is lower than the predetermined pressure, the pressure valve 114 is closed and the cooling water flows from the cooling water passage 101 for the cylinder head exhaust passage to the cooling water passage 93 for connection. And the cooling water passage 9 for connection
The cooling water that has flowed into the nozzle 3 flows into the cylinder cooling water passage 91 and the combustion chamber cooling water passage 103 via the communication passage 106 of the guide exhaust 23, and cools the cylinder 11 and the combustion chamber 11a. The cylinder cooling water passage 91 and the combustion chamber cooling water passage 103 join at their upper ends. A thermostat 119 is provided downstream of this merging portion. Two thermostats 119, one for the right cylinder 11 and one for the left cylinder 11, are attached to the upper surface of the cylinder block 20. Then, the cooling water discharged from both thermostats 119 flows into the return cooling water passage 94 provided downstream of the thermostats 119. The thermostat 119 opens when the temperature of the cooling water is equal to or higher than a predetermined temperature, that is, the set temperature of the thermostat 119, and the cooling water flows from the cylinder cooling water passage 91 and the combustion chamber cooling water passage 103 to the return cooling water passage 94. On the contrary, when the temperature of the cooling water is lower than the predetermined temperature, it is closed and the cylinder cooling water passage 9
1 and combustion chamber cooling water channel 103 to return cooling water channel 9
Block or narrow the flow of cooling water to 4.

By the way, when the thermostat 119 is opened, the pressure of the cooling water is lowered and the pressure valve 114 is closed. On the other hand, when the thermostat 119 is closed, the pressure of the cooling water rises and the above-mentioned pressure valve 114 is opened.

In this way, the return cooling water passage 9
The cooling water flowing into 4 flows from the lower end of the return cooling water passage 94 into the water reservoir 86 through the cooling water passage 121 of the guide exhaust 23 and a cooling water passage (not shown). The water accumulated in the water sump 86 is stored in the oil pan 51 and the muffler 8.
4 is cooling. Then, when the cooling water accumulated in the water reservoir 86 begins to overflow, as described above, the overflow opening 90
Through the drainage channel 88 of the muffler 84 and the like, and is drained to the outside of the outboard motor from a drainage port (not shown) formed in the lower casing 4.

In FIG. 4, reference numeral 126 is an alternator for power generation, reference numeral 127 is a belt for driving the alternator, and reference numeral 128 is a starter motor for starting.

When the engine 7 constructed as described above operates, high temperature combustion gas is discharged to the cylinder head exhaust passage 32 and the cylinder block exhaust passage 79. The exhaust gas is cooled in the cylinder head exhaust passage cooling water passage 101. Then, the cylinder block exhaust passage 79
The heat is prevented from being transferred to the cylinder cooling water passage 91 and the cylinder 11 in the heat insulating space 95. On the other hand, as described above, the cooling water whose temperature is controlled by the thermostat 119 flows through the cylinder cooling water passage 91 to cool the cylinder 11. Further, the cooling water passage 103 for the combustion chamber
Cooling water cools the combustion chamber 11a.

When the air in the heat insulating space 95 is warmed by the heat of the cylinder block exhaust passage 79, the warm air in the heat insulating space 95 ends 95 in the heat insulating space 95.
The air is discharged from the open portions at the upper ends of the a and the corner portions 95b, and cold outside air enters from the open portions at the lower ends of the end portions 95a of the heat insulating space 95 for natural ventilation.

As described above, in this embodiment, the cylinder block 20 is provided with the cylinder block exhaust passage 79, and the number of parts and the mounting thereof are greater than those in which the exhaust passage is separately formed by an exhaust pipe or the like. The number of steps can be reduced and the engine can be downsized. Moreover, since the heat insulating space 95 is formed between the cylinder block exhaust passage 79 and the cylinder cooling water passage 91 in spite of the reduction in the number of parts and miniaturization in this way, the cylinder block exhaust is formed. The heat of the passage 79 is transferred to the cylinder 11 and the cooling water passage 91 for the cylinder.
Can be prevented by the heat insulating space 95. Further, the cylinder block exhaust passage 79 is arranged so as to be biased to the left side or the right side with respect to the cylinder 11, so that the temperature distribution around the cylinder 11 may become uneven. However, as described above, the insulating space 95
Is provided to block heat from the cylinder block exhaust passage 79. As a result, it is possible to reduce the uneven temperature distribution around the cylinder due to the heat of the cylinder block exhaust passage 79.

The return cooling water passage 94 is arranged in the cylinder block 20 and is provided at a corner of V formed between the plurality of cylinders 11. Therefore, the engine 7 can be made compact and the number of parts can be reduced as compared with the case where the return cooling water passage 94 is arranged at another place.

Further, since the connection cooling water passage 93 is provided adjacent to the cylinder block exhaust passage 79, the cylinder block exhaust passage 79 is formed in the connection cooling water passage 93.
Can be cooled.

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 embodiment, the engine 7 has six cylinders, but the number of cylinders and the like can be changed as appropriate.

(2) The locations of the thermostat 119 and the pressure valve 114 can be changed as appropriate.

[0038]

According to the present invention, since the exhaust passage for exhausting the combustion gas is provided in the cylinder block, the number of parts and the number of mounting steps can be reduced as compared with the case where the exhaust passage is separately constituted by an exhaust pipe. The engine can be downsized as well as being reduced. Moreover, although the number of parts is reduced and the size is reduced, a heat insulating space is formed between the exhaust passage and the cylinder cooling water passage. Transmission to the cylinder cooling water passage can be prevented in the heat insulating space. Therefore, it is possible to reduce the temperature of the cylinder and the uneven temperature distribution around the cylinder. As a result, the engine can achieve the desired performance.

In addition, the heat insulating space may be provided inside the cylinder block and may be provided with an opening portion that is open to the outside of the cylinder block. In this case, since the air in the heat insulating space can be naturally ventilated with the air outside the cylinder block through the opening, heat does not stay in the heat insulating space. Therefore, even if the heat insulating space is heated, the heat insulating performance of the heat insulating space is less likely to deteriorate.

Further, the cylinders of the engine are arranged in the cylinder block so as to be distributed in the left-right direction so as to form a V-shape, and a common cylinder block exhaust passage for exhausting combustion gas of the left and right cylinders is provided. There is. Therefore, the exhaust passage for exhausting the combustion gas of the left and right cylinders can be downsized as compared with the case where each exhaust cylinder is provided. In addition, the cylinder block exhaust passage is arranged between the cylinders that are arranged adjacent to each other in the V-shape on the left and right, and can be further downsized. Moreover, despite the miniaturization as described above, since the heat insulating space is formed between the exhaust passage and the cooling water passage for the cylinder, the heat of the exhaust passage can be transferred to the cooling water passage for the cylinder and the cylinder. Can be prevented by the space for heat insulation.

Further, a right heat insulating space and a left heat insulating space are provided, and both heat insulating spaces communicate with each other at a communicating portion, and the upper end of this communicating portion is opened to the outside of the cylinder block. There is a case. In this case, since one open portion can be commonly used for the right heat insulating space and the left heat insulating space, the number of open portions can be reduced, and the number of machining steps of the cylinder block and The installation space of the open part can be reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of an outboard motor according to the present invention.

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

FIG. 3 is an explanatory diagram for explaining a heat insulating space.

FIG. 4 is a plan view showing an internal structure of the outboard motor of FIG.

5 is a cross-sectional view for explaining the internal structure of the outboard motor of FIG.

FIG. 6 is an enlarged sectional view of a main part of FIG. 5;

FIG. 7 is an explanatory diagram for explaining a throttle valve and a surge tank.

FIG. 8 is a circuit diagram of a cooling water channel.

[Explanation of symbols]

 7 Engine 11 Cylinder 11a Combustion Chamber 20 Cylinder Block 22 Cylinder Head 32 Cylinder Head Exhaust Passage 79 Cylinder Block Exhaust Passage 91 Cylinder Cooling Water Channel 95 Insulation Space 95b Corner (Communication Portion)

Claims (4)

[Claims] 1. An exhaust passage for exhausting combustion gas of an engine and a cylinder cooling water passage for cooling a cylinder of the engine are provided in a cylinder block of the engine, and the exhaust passage and the cylinder cooling water passage are provided. An outboard engine, characterized in that a heat insulating space is formed between the two. 2. The heat insulating space is provided in the cylinder block, and the heat insulating space has an opening portion open to the outside of the cylinder block. Outboard engine. 3. The cylinders of the engine are arranged in a cylinder block so as to be distributed in the left-right direction to form a V-shape, and the cylinder block is provided with a cylinder cooling water passage for cooling the cylinder. Further, the combustion chamber side of the left cylinder is closed by the left cylinder head, while the combustion chamber side of the right cylinder is closed by the right cylinder head, the exhaust passage for exhausting the combustion gas of the engine, A cylinder head exhaust passage provided in each of the left and right cylinder heads and a cylinder block exhaust passage provided in a cylinder block of the engine are provided. It is connected between the cylinders that are in communication and are adjacent to each other in a V shape. An outboard motor engine, wherein a heat insulating space is formed between the cylinder block exhaust passage and the cylinder cooling water passage. 4. The cylinders of the engine are arranged in a cylinder block so as to be distributed in the left-right direction so as to form a V-shape, and in this cylinder block, a left-side cylinder cooling water channel for cooling the left-side cylinder is provided. The right cylinder cooling water passage for cooling the right cylinder is provided, and the combustion chamber side of the left cylinder is closed by the left cylinder head, while the combustion chamber side of the right cylinder is The exhaust passage, which is closed by a cylinder head and exhausts the combustion gas of the engine, includes a cylinder head exhaust passage provided in each of the left and right cylinder heads and a cylinder block exhaust passage provided in a cylinder block of the engine. And the cylinder block exhaust passage communicates with the left and right cylinder head exhaust passages. Both of them are arranged between the cylinders that are adjacent to each other in the V-shape on the left and right, and a right heat insulating space is provided between the cylinder block exhaust passage and the right cylinder cooling water passage. ,on the other hand,
A left heat insulating space is formed between the cylinder block exhaust passage and the left cylinder cooling water passage, and the right heat insulating space and the left heat insulating space communicate with each other at a communicating portion. The engine of the outboard motor is characterized in that the upper end of this communication portion is open to the outside of the cylinder block.