JPH0730692B2 - Cylinder head liquid cooling device for sub-chamber engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention, in a sub-chamber engine with low flame-retardant noise and clean flue gas, cools a portion around the sub-chamber of the cylinder head strongly, The present invention relates to a cylinder head liquid cooling device for a sub-chamber engine in which the weight of the cylinder head is reduced.

«Prior art» Conventionally, as a cylinder head liquid cooling device for a diesel engine, for example, as disclosed in Japanese Utility Model Laid-Open No. 59-88214, the entire area inside the wall of the cylinder head of a direct injection engine is used. There is one that forms an oil jacket and circulates oil to liquid-cool the entire cylinder head.

In this conventional direct injection engine cylinder head oil cooling device, the outlet of the oil jacket formed in the cylinder head is communicated with the inlet of the oil jacket via an oil cooler and an oil supply pump, and is cooled by the oil cooler. Cooling oil is circulated in the oil jacket. The oil cooler is cooled by the cooling air that is pressure-fed by the cooling fan.

However, in this conventional example, since the cooling oil absorbs heat from the entire cylinder head, a large amount of heat is absorbed by the cooling oil, a large amount of cooling oil is required, and the weight of the cylinder head becomes large. It is necessary to increase the capacity of the oil cooler that cools the cooling oil, which causes a problem that the oil cooler becomes large.

In addition, since the cooling oil contacts the entire circumferential wall of the intake port inside the head jacket after cooling the entire circumference of the cylinder to a high temperature, it cannot cool the intake port strongly and fills it. You cannot increase efficiency.

On the other hand, in a sub-chamber engine that produces less combustion noise and clean combustion exhaust gas compared to a direct injection engine, a conventional cylinder head fluid example device is
Some are disclosed in Japanese Patent No. 51956.

In this conventional cylinder head liquid cooling device for a sub-chamber engine, a cooling liquid passage is formed in the cylinder side wall of the cylinder head, the cooling liquid is supplied to the inlet of the cylinder head internal passage, and the outlet of the passage is The cooling liquid is circulated in communication with the in-cylinder passage, and the sub chamber of the cylinder head and other parts are cooled by air cooling.

<< Problems to be Solved by the Invention >> However, in the above-described conventional cylinder head liquid cooling device for a sub-chamber engine, only the cylinder side meat wall portion of the cylinder head is liquid-cooled, and particularly in the sub-chamber with a high heat load. Since the surrounding meat wall portion is only air-cooled, the cooling is insufficient and it overheats. For this reason, the thermal stress of the cylinder head increases and cracks are likely to occur, resulting in poor durability.

Further, there is a problem that thermal distortion occurs due to overheating around the sub chamber, and gas leaks from the joint surface with the cylinder block.

As is well known, the sub-chamber has a large volume ratio of the combustion chamber, and in this sub-chamber with a large volume ratio, the pressure rapidly increases during the explosive combustion period following the ignition delay period of the combustion process. As a result, large combustion noise is concentrated and generated.

The large combustion noise generated in this sub-chamber permeates the peripheral wall of the sub-chamber, is then amplified by vibrating the heat radiation fins of the sub-chamber peripheral wall, and is also directly radiated to the outside. The amount of leakage is large and the engine noise is loud.

Further, it is not described that the peripheral wall of the intake port is strongly cooled all over, so that the charging efficiency cannot be expected to be improved.

The present invention has been made in consideration of the above circumstances, and is a small-sized, lightweight and sufficiently high cooling performance in a sub-chamber engine with low combustion noise and clean combustion exhaust gas. It is an object of the present invention to provide a cylinder head liquid cooling device for a sub-chamber engine, which has a small amount of leakage to the cylinder chamber and a high filling efficiency as required.

<< Means for Solving the Problems >> In order to achieve the above-mentioned object, the present invention provides, for example, FIG.
As shown in FIG. 3, it is characterized in that it is configured as follows.

That is, in the cylinder head 8 of the subchamber engine 1, a cooling liquid jacket 9 is formed around the subchamber 22 on one side of the intake port 24 and the exhaust port 25. It is formed so as to cover the entire peripheral wall 22a of 22. On the other hand, a cooling air passage 32 is formed on the other side of the intake port 24 and the exhaust port 25, and the main combustion chamber 41 of the subchamber engine 1 is formed. Of the main combustion chamber lid of the cylinder head 8 facing the
The cooling air passage 32 is exposed to 42, and the main combustion chamber lid wall portion 42 that is directly heated by the combustion heat in the main combustion chamber 41 is configured to be cooled by the cooling air that flows in the cooling air passage 32. The outlet 10 of the cooling liquid jacket 9 is connected to the inlet 12 of the cooling liquid cooler 11.
The cooling liquid in the cooling liquid jacket 9 can be circulated through the cooling liquid cooler 11 so that the cooling fan 30 and the wind guide case 31 are arranged in the engine 1 and the cooling fan 30 raises the cooling liquid. The cooling air is guided to the cooling air passage 32 of the cylinder head 8 by the air guide case 31.

It should be noted that the following improved configuration may be added as necessary.

That is, the intake port 24 is formed by running from the front side portion of the exhaust port 25 toward the one lateral side portion and across the front side portion of the cooling liquid jacket 9, and among the peripheral wall 43 of the intake port 24. , The front side peripheral wall portion 43a faces the cooling air guided from the air guide case 31,
The front end wall portion 43b faces the cooling air passage 32, and the rear side peripheral wall portion 43c faces the cooling liquid jacket 9.

<< Working >> The present invention operates as follows.

In the cylinder head 8, the peripheral portion of the sub chamber 22 having a particularly high heat load is strongly liquid-cooled by the cooling liquid in the cooling liquid jacket 9, while the main combustion chamber having a low heat load separated from the sub chamber 22 is used. The wall portion 42 is gently air-cooled by the cooling air in the cooling air passage 32. Therefore, the temperature drop between the two parts is small,
The thermal stress of the cylinder head 8 is reduced.

As a result, the cylinder head 8 is less likely to crack and has improved durability, and thermal strain is less likely to occur, so that gas leakage from the joint surface with the cylinder block can be strongly prevented.

Further, the main combustion chamber wall portion 42, which is directly heated by the combustion heat in the main combustion chamber 41, is cooled by the cooling air flowing in the cooling air passage 32 facing this.

Therefore, the amount of heat absorbed by the cooling liquid in the cylinder head 8 is reduced by the amount of liquid cooling of the main combustion chamber wall portion 42 that is directly heated by the combustion heat in the main combustion chamber 41. The amount of cooling liquid required for cooling 8 is small, and the weight of the cylinder head 8 can be reduced. Moreover, the cooling liquid cooler 11 can also be downsized. As a result, the entire engine can be made smaller and lighter.

Further, since the cooling liquid jacket 9 is formed around the sub chamber 22, for example, at the time of cold start of the engine in the cold season, etc.
The combustion heat of 22 heats the cooling liquid in the cooling liquid jacket 9. As a result, the sub-chamber 22 is kept warm by the cooling liquid in the cooling liquid jacket 9 and is not directly cooled by the excessively low temperature cooling air, so that it is prevented from being overcooled.

And, as is well known, the sub-chamber 22 has a large volume ratio, and in the sub-chamber 22 of this large volume, the pressure rapidly increases during the explosive combustion period following the ignition delay period of the combustion process, Large combustion noise is concentrated and generated.

When the large combustion noise generated in the sub chamber 22 propagates into the cooling liquid jacket 9 after passing through the peripheral wall 22a of the sub chamber 22, the vibration energy of the sound is attenuated and the cooling liquid jacket 9 It is similarly attenuated when propagating to the outer peripheral wall 9a.

Due to this double damping action, the amount of combustion noise leaked to the outside is greatly reduced, and the operating noise of the engine becomes quiet.

When adding the improved configuration, the cooling fan 30
When the cooling air generated by the above is guided by the wind guide case 31 and blown toward the cylinder head 8 from the front,
First, the front peripheral wall portion 43a of the peripheral wall 43 of the intake port 24 is strongly and strongly blown against the front peripheral wall portion 43a to strongly cool the front peripheral wall portion 43a.

Next, this large amount of cooling air flows along the front peripheral wall portion 43a, and when it enters the cooling air passage 32, it makes strong contact with the tip wall portion 43b, and strongly cools the tip wall portion 43b.

When the cooling liquid cooled by the cooling liquid cooler 11 passes through the cooling liquid jacket 9, the peripheral wall 43 of the intake port 24 is cooled.
A large amount of contact is made with the rear side peripheral wall portion 43c, and the rear side peripheral wall portion 43c is strongly cooled.

As described above, of the peripheral wall 43 of the intake port 24, the front peripheral wall portion 43a and the front end wall portion 43b thereof are strongly cooled by the strong blow and contact of a large amount of cooling air, and the cooling air is less likely to wrap around after that. Since the side peripheral wall portion 43c is strongly cooled by a large amount of contact with the cooling liquid, the intake port 24 can be strongly cooled entirely by the synergistic action thereof, and the intake density can be increased to enhance the charging efficiency.

In the present invention, the cooling fluid system connecting the cooling fluid jacket 9 and the cooling fluid cooler 11 can be provided independently of the lubricating oil system of the engine 1, but the cooling fluid system is the lubricating oil system of the engine 1. If the lubricating oil of the engine 1 is branched to be used for cooling the cylinder head 8, it is advantageous because the configuration of the entire engine can be simplified.

Further, when the present invention is applied to the sub-chamber overhead valve engine, it is preferable that the cooling air passage 32 is formed so that the cooling air comes into contact with the peripheral wall of at least one of the intake port 24 and the exhaust port 25. According to this structure, when the cooling air comes into contact with the intake port 24, the intake air flowing through the inside is cooled, and when it comes into contact with the exhaust port 25, the exhaust port 25 is cooled, so that the exhaust port 25 moves to the intake port 24. The heat transfer to the intake air is suppressed, and the intake air is prevented from being heated by the exhaust heat.
As a result, the intake air is kept cool, the charging efficiency is increased, and the output of the engine is increased.

Further, when the present invention is applied to a subchamber overhead valve engine, a cooling liquid jacket 9 formed in the cylinder head 8 is used.
Is formed so that a part of the cooling liquid supply passage 7 leading to the above-mentioned passage along the wall surface 8a of the cylinder head 8 on the cylinder block 17 side passes through the intervalve portion 21 between the intake valve hole 19 and the exhaust valve 20. Is preferred. According to this structure, the intervalve portion 21 is cooled by the cooling liquid, the heat transfer from the exhaust valve side to the intake valve side is suppressed, and the heating of the intake air by the exhaust heat is suppressed. The output of the engine can be increased.

«Examples» Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional rear view of a main part of a sub-chamber diesel engine to which an embodiment of the present invention is applied, FIG. 2 is a cross-sectional plan view of a cylinder head thereof, and FIG. 3 is a vertical sectional view of the engine. It is a side view.

As shown in FIG. 3, on the rear end wall 2a of the crankcase 2 of the engine 1, an oil is pumped up from the inside of an oil pan 3 formed at the bottom of the crankcase 2 through an oil filter 4. The supply pump 5 is assembled. The lubricating oil discharged from the oil supply pump 5 is pressure-fed to each portion of the engine 1 that requires lubrication through the lubricating oil supply passage 6, and the cooling oil branched from the middle of the lubricating oil supply passage 6 Through the supply path 7, it is supplied as a cooling liquid to a cooling liquid jacket (oil jacket) 9 formed in the cylinder head 8 (see FIGS. 1 and 2).

The outlet 10 of the oil jacket 9 is connected to the inlet 12 of the oil cooler 11, and the outlet 13 of the oil cooler 11 communicates with the oil pan 3 via the push rod insertion chamber 14.

The cooling oil supply passage 7 is composed of an inlet passage 15, a cylinder oil jacket 16, and an introduction passage 18 which are communicated in order. The starting end portion of the inlet passage 15 is branched and connected in the middle of the lubricating oil supply passage 6, and the starting end portion is connected to the bottom portion of the cylinder oil jacket 16. The cylinder oil jacket 16 is formed between the cylinder 17a and the push rod insertion chamber 14, and its upper end is opened at the joint surface between the cylinder block 17 and the cylinder head 8. The start end of the introduction passage 18 is opened to face the upper end opening of the cylinder oil jacket 16, and the end thereof is communicated with the inlet 9a formed in the lower portion of the oil jacket 9. This introduction passage
The part in the middle of 18 is the oil jacket 16 for cylinder,
Wall surface of cylinder head 8 on the cylinder block side (lower wall)
8a along the 8a between the intake valve hole 19 and the exhaust valve hole 20 valve portion 21
It is formed to pass through.

By the way, the cylinder head 8 has an intake valve hole 19 and an exhaust valve hole 20 formed side by side in the axial direction of the crankshaft 23.
And an intake port 24 communicating with the intake valve hole 19 and an exhaust valve hole 20.
Exhaust port 25 communicating with the intake valve hole 19 and exhaust valve hole 20
A sub-chamber 22 disposed on one lateral side of the push rod insertion chamber 14 disposed on the other lateral side of the intake valve hole 19 and the exhaust valve hole 20.
And are provided. The oil jacket 9 is a sub chamber
22 is formed around the peripheral wall 22a of the sub-chamber 22, and is formed so as to cover the entire peripheral wall 22a of the sub-chamber 22, and the front side is the peripheral wall of the intake port 24,
The right side is the peripheral wall of the intake port 24 and the peripheral wall of the exhaust port 25,
The rear side is partitioned by partition walls 26. Further, the left side of the oil jacket 9 is defined by a lid 29 that is connected to a mounting portion 28 of the intake pipe 27. The outlet 10 of the oil jacket 9 is opened in the upper part inside the oil jacket 9.

Further, a front end portion of a crank shaft 23 projects from a front side of a front end wall 2b of a crank case 2 of the engine 1, and a cooling fan 30 is fixed to the front end portion of the crank shaft 23. The cooling air generated by the cooling fan 30 is supplied to the cylinder block 17,
An air guide case 31 that guides the cylinder head 8 and the oil cooler 11 is fixed to the front side of the crank case 2.

A cooling air passage 32 for passing cooling air is formed in a portion of the cylinder head 8 other than the periphery of the sub chamber 22. This cooling air passage 32
Is formed by running in the front-rear direction between both peripheral walls of the intake port 24 and the exhaust port 25 and the push rod insertion chamber 14.

Cylinder head 8 facing the main combustion chamber 41 of the sub-chamber engine 1
The main combustion chamber wall portion 42 of the main combustion chamber lid wall portion 42 that is directly heated by the combustion heat in the main combustion chamber 41 by facing the cooling air passage 32.
Is configured to be cooled by the cooling air flowing through the cooling air passage 32.

The cooling air generated by the cooling fan 30 is transferred to the wind guide case 31.
Is formed so as to come into contact with the main combustion chamber lid wall portion 42 and both peripheral walls of the intake port 24 and the exhaust port 25 when flowing in the cooling air passage 32 from the front to the rear. .

The intake port 24 is run from the front side of the exhaust port 25 toward the one lateral side, and the coolant jacket 9
It is formed by crossing the front side of the.

Of the peripheral wall 43 of the intake port 24, its front peripheral wall portion 43a faces the air guide case 31, its front end wall portion 43b faces the cooling air guided from the cooling air passage 32, and its rear peripheral wall portion 43c. Faces the coolant jacket 9.

In the above configuration, on the other hand, the lubricating oil in the oil pan 3 is pumped out by the oil supply pump 5, and a part of the lubricating oil is supplied to the oil jacket 9 via a part of the lubricating oil supply passage 6 and the cooling oil supply passage 7. Supplied. The lubricating oil cools the wall of the cylinder 17a between the cylinder 17a and the push rod insertion chamber 14 where heat is relatively likely to accumulate, while the lubricating oil is rising in the cylinder oil jacket 16 of the cooling oil supply passage 7. In addition, the intervalve portion 21 is strongly cooled while passing through the conduction passage 18. Then, the lubricating oil that has entered the oil jacket 9 is sent to the oil cooler 11 after cooling the sub-chamber 22 strongly from the surroundings, is cooled while passing through the oil cooler 11, and then passes through the push rod insertion chamber 14. Oil pan 3
Returned to.

On the other hand, the cooling air generated by the cooling fan 30 is the wind guide case.
A guide 31 guides the front surface of the cylinder block 17, the front surface of the cylinder head 8 and the oil cooler 11. The cooling air guided to the front surface of the cylinder block 17 contacts the circumferential surface of the cylinder block 17 to cool the cylinder block 17 entirely, and the cooling air guided to the front surface of the cylinder head 8 cools the cooling passage of the cylinder head 8. Passing through 32, main combustion chamber lid wall
42, and contacts the peripheral walls of the intake port 24 and the exhaust port 25 to cool them. Further, the cooling air guided by the oil cooler 11 blows through the oil cooler 11 from the bottom to the top to cool the lubricating oil circulating in the oil cooler 11.

In this way, since the oil jacket 9 is formed around the sub chamber 22 of the cylinder head 8 and the lubricating oil pumped up from the oil pan 3 is circulated in the oil jacket 9,
In particular, the surroundings of the sub-chamber 22, which is apt to reach a high temperature, is strongly cooled and is not overheated. For this reason, the cylinder head 8 has small thermal stress, cracks hardly occur, and thermal strain hardly occurs.

On the other hand, since the portion of the cylinder head 8 other than the periphery of the sub chamber 22 is air-cooled by the cooling air passing through the cooling air passage 32, the lubricating oil supplied to the oil jacket 9 is heated by the heat of the portion around the sub chamber 22. The amount of heat absorbed by the lubricating oil is much smaller than when the entire cylinder head 8 is liquid-cooled.

As a result, the amount of the lubricating oil for cooling required for cooling the cylinder head 8 is small, the cylinder head 8 can be made lighter, and the volume of the oil pan 3 can be made smaller to downsize the engine 1. be able to. Moreover, since the amount of heat supplied by the lubricating oil is small, the oil cooler 11 can be downsized.

Further, since the oil jacket 9 is formed around the sub chamber 22, the lubricating oil in the oil jacket 9 is heated by the combustion heat of the sub chamber 22 at the time of cold start in the cold season, for example. As a result, the sub-chamber 22 is kept warm by the lubricating oil in the oil jacket 9 and is not directly cooled by the excessively low temperature cooling air, so that it is prevented from becoming a supercooled state, so that the engine is started. The subsequent warm-up time can be shortened and the operation can be started immediately.

Further, as described above, the lubricating oil is introduced into the oil cooler 11 immediately after being heated by the oil jacket 9, and
After being cooled in 11, it is returned to the oil pan 3. And
The oil returned to the oil pan 3 is pumped out by the oil supply pump 5 and circulates in the oil jacket 9 as described above.

Therefore, since the lubricating oil returned from the oil cooler 11 to the oil pan 3 is cooled, the oil temperature in the oil pan 3 does not rise to a high temperature, and deterioration of the lubricating oil can be prevented for a long time.

Further, since the introduction passage 18 enters the oil jacket 9 along the lower wall 8a of the cylinder head 8 and exits from the oil jacket 9 through the outlet 10 at the upper part of the oil jacket 9, lubrication in the oil jacket 9 is performed. The direction of oil flow and the direction of natural convection match, the flow resistance of lubricating oil is reduced, and the load on the oil supply pump 5 is reduced. In addition, the lubricating oil having a high temperature rises to the upper portion of the oil jacket 9 and is smoothly discharged from the outlet 10. Therefore, the high temperature lubricating oil does not stay in the oil jacket 9, and as a result, the lubricating oil in the oil jacket 9 is prevented. The cooling effect due to is not impaired, and the sub chamber 22 can be cooled more strongly.

Further, since the introduction passage 18 is formed so as to pass through the intervalve portion 21 between the intake valve hole 19 and the exhaust valve hole 20, the exhaust valve hole 20
Since the intake oil 19 side is suppressed from being heated by the lubricating oil absorbing the heat transfer from the air valve hole 19 side, the intake air is suppressed from being heated by the exhaust heat, and the charging efficiency is further enhanced. The output of the engine 1 is further increased.

The cooling liquid system connecting the cooling liquid jacket 9, the cooling liquid cooler 11, and the cooling liquid supply pump 5 can be provided independently of the lubricating oil system of the engine 1, but in the present embodiment, the cooling liquid system is used. Since the cooling liquid supply pump 5 is also used as the oil supply pump of the lubricating oil system of the engine 1 and the lubricating oil of the engine 1 is used for liquid cooling of the cylinder head 8, the overall configuration of the engine is simple.

<< Effect of the Invention >> The present invention is configured and operates as described above,
It has the following effects.

(B) In the cylinder head, the peripheral portion of the sub chamber with a particularly high heat load is strongly liquid cooled by the cooling liquid in the cooling liquid jacket, while the main combustion lid wall with a low heat load is separated from the sub chamber. The part is gently air cooled with cooling air in the cooling air duct. As a result, the temperature difference between the two parts becomes small and the thermal stress in the cylinder head becomes small.

As a result, the cylinder head is less likely to be cracked and has improved durability, and thermal strain is less likely to occur, so that gas leakage from the joint surface with the cylinder block can be strongly prevented.

(B) The amount of heat supply of the cooling liquid in the cylinder head is reduced as much as the liquid cooling of the lid wall of the main combustion chamber that is directly heated by the combustion heat in the main combustion chamber reduces the cooling of the cylinder head. The amount of cooling liquid required is small and the cylinder head can be made lighter. Moreover, the cooling liquid cooler can be downsized. As a result, the entire engine can be made smaller and lighter.

(C) Since the cooling liquid jacket is formed around the sub chamber, the cooling liquid in the cooling liquid jacket is heated by the combustion heat of the sub chamber when the engine is cold-started, for example, in the cold season. As a result, the sub chamber is kept warm by the cooling liquid in the cooling liquid jacket, and is not directly cooled by the excessively low temperature cooling air, preventing overcooling. Can be shortened and the operation can be quickly started.

(D) The large combustion noise generated in the sub chamber 22
After passing through the peripheral wall 22a, the vibration energy of sound is attenuated when propagating into the cooling liquid jacket 9, and also when propagating to the outer peripheral wall 9a of the cooling liquid jacket 9.

Due to this double damping action, the amount of leakage of combustion noise to the outside is greatly reduced, and the engine operating noise becomes quiet.

(E) The intake port 24 is formed by running from the front side of the exhaust port 25 toward the one lateral side and crossing the front side of the cooling liquid jacket 9 to form a peripheral wall of the intake port 24. Of the 43, the front side peripheral wall portion 43a faces the wind guide case 31, the front end wall portion 43b faces the cooling air passage 32, and the rear side peripheral wall portion 43c faces the cooling liquid jacket 9. It has the following advantages:

When the cooling wind generated by the cooling fan 30 is guided by the wind guide case 31 and blown toward the cylinder head 8 from the front, first, the front peripheral wall portion of the peripheral wall 43 of the intake port 24 is first.
The front side peripheral wall portion 43a is strongly cooled by blowing a large amount against the 43a.

Next, this large amount of cooling air flows along the front peripheral wall portion 43a, and when it enters the cooling air passage 32, it makes strong contact with the tip wall portion 43b, and strongly cools the tip wall portion 43b.

When the cooling liquid cooled by the cooling liquid cooler 11 passes through the cooling liquid jacket 9, the peripheral wall 43 of the intake port 24 is cooled.
A large amount of contact is made with the rear side peripheral wall portion 43c, and the rear side peripheral wall portion 43c is strongly cooled.

As described above, of the peripheral wall 43 of the intake port 24, the front peripheral wall portion 43a and the front end wall portion 43b thereof are strongly cooled by the strong blow and contact of a large amount of cooling air, and the cooling air is less likely to wrap around after that. Since the side peripheral wall portion 43c is strongly cooled by a large amount of contact with the cooling liquid, the intake port 24 can be strongly cooled entirely by the synergistic action thereof, and the intake density can be increased to enhance the charging efficiency.

[Brief description of drawings]

FIG. 1 is a vertical sectional rear view of a main part of a sub-chamber diesel engine to which an embodiment of the present invention is applied, FIG. 2 is a cross-sectional plan view of a cylinder head thereof, and FIG. 3 is a vertical sectional view of the engine. It is a side view. 1 ... Engine, 7 ... Coolant supply passage, 8 ... Cylinder head, 8a ... Cylinder block side wall of cylinder head, 9 ... Coolant jacket, 9a ... Coolant jacket inlet, 10 ... Coolant jacket outlet, 11 ... Coolant cooler, 12 ... Coolant cooler inlet, 17 ... Cylinder block, 19 ... Intake valve hole, 20 ... Exhaust valve hole, 21 ... Interval, 22 …… Sub chamber, 22a …… Sub chamber peripheral wall, 24 …… Intake port, 25 …… Exhaust port, 30 …… Cooling fan, 31 …… Wind guide case, 32 …… Cooling air passage, 41 …… Main combustion Chamber, 42 ... Main combustion chamber lid wall part, 43 ... Intake port peripheral wall, 43a ... Intake port peripheral wall front side peripheral wall part, 43b ... Tip wall part, 4
3c …… The rear side wall part.

Claims (4)

[Claims] 1. A cooling liquid jacket is provided around a sub chamber (22) on one side of an intake port (24) and an exhaust port (25) in a cylinder head (8) of a sub chamber engine (1). (9) is formed, and the cooling liquid jacket (9) is formed on the peripheral wall (22) of the sub chamber (22).
It is formed so as to cover all of a), while the intake port (24) and exhaust port (2
On the other side of 5), a main combustion chamber lid wall portion (42) of the cylinder head (8) that forms a cooling air passage (32) and faces the main combustion chamber (41) of the subchamber engine (1). To the cooling air duct (3
2), the main combustion chamber lid wall portion (42) directly heated by the combustion heat in the main combustion chamber (41) is cooled by the cooling air flowing in the cooling air passage (32). Then, the outlet (10) of the cooling liquid jacket (9) is communicated with the inlet (12) of the cooling liquid cooler (11), and the cooling liquid in the cooling liquid jacket (9) is passed through the cooling liquid cooler (11). The cooling fan (30) and the air guide case (31) are arranged in the engine (1) so as to be circulated, and the cooling air generated by the cooling fan (30) is transferred to the cylinder head (31) by the air guide case (31). A liquid cooling device for a cylinder head of a sub-chamber engine, characterized in that the liquid is guided to the cooling air passage (32) of 8). 2. The intake port (24) is an exhaust port (2
Run from the front side of 5) to the one lateral side,
The cooling liquid jacket (9) is formed by crossing the front side portion, and the front side peripheral wall portion (43a) of the peripheral wall (43) of the intake port (24) is guided from the wind guide case (31). It is exposed to cooling air, and its tip wall (43b) is
2. The cylinder head fluid for a sub-chamber engine according to claim 1, characterized in that it is configured so as to face the second side and the rear side peripheral wall portion (43c) faces the cooling liquid jacket (9). Refrigerator. 3. The cylinder head (8) has an intake valve hole (1).
9), an exhaust valve hole (20), an intake port (24) and an exhaust port (25), and the cooling air passage (32) has an intake port (2).
The cylinder head liquid cooling device for a sub-chamber engine according to claim 1 or 2, wherein cooling air is formed in contact with at least one peripheral wall of the exhaust port (25) and the exhaust port (25). 4. The cylinder head (8) is provided with an intake valve hole (1).
9), an exhaust valve hole (20), an intake port (24) and an exhaust port (25), and a part of a cooling liquid supply passage (7) reaching a cooling liquid jacket (9) formed in the cylinder head (8). Is an intake valve hole (19) and an exhaust valve hole (20) along the wall surface (8a) of the cylinder head (8) on the cylinder block (17) side.
The cylinder head liquid cooling device for a sub-chamber engine according to claim 1, 2 or 3, which is formed so as to pass through an intervalve portion (21) between and.