JP2524876B2 - Cylinder head liquid cooling device for sub-chamber engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is a sub-chamber engine with low combustion noise and clean fuel exhaust gas. The present invention relates to a cylinder head liquid cooling device for a sub-chamber engine with a lightweight head.

<Prior Art> Conventionally, as a cylinder head liquid cooling device for a diesel engine, for example, as disclosed in Japanese Utility Model Application Laid-Open No. Sho 59-88214, a cylinder head of a direct injection type engine has an entire wall surface of a cylinder head. There is one that forms an oil jacket and circulates oil to liquid-cool the entire cylinder head.

In this conventional cylinder head oil cooling device for a direct injection engine, an outlet that opens in the vertical center of an oil jacket formed in the entire cylinder head is connected to the inlet of the oil jacket via an oil cooler, and the oil cooler is used. Cooled cooling oil is circulated in an oil jacket, and the oil cooler is cooled by cooling air that is pressure-fed by a cooling fan.

However, in this conventional example, since the cooling oil absorbs heat from the entire cylinder head, the amount of heat absorbed by the cooling oil increases and a large amount of cooling oil is required. Therefore, the weight of the cylinder head is increased, and the capacity of the oil cooler for cooling the oil for cooling the cylinder head needs to be increased, which causes a problem of increase in size.

Also, in addition to the large amount of cooling oil, an oil jacket is formed over the entire area of the cylinder head, and the outlet formed at the center of the oil jacket in the vertical direction is in communication with the oil cooler. There is a problem that the cooling oil causes natural convection and cannot circulate smoothly, and that the cooling oil having a high temperature stays in the oil jacket.

On the other hand, in a sub-chamber engine that produces less combustion noise and produces cleaner combustion exhaust gas than a direct injection engine, a conventional cylinder head liquid cooling device is used.
There is one disclosed in Japanese Patent Publication No. 51956.

In this conventional cylinder head fluid example device for a sub-chamber engine, a coolant passage is formed in the cylinder side wall of the cylinder head, the coolant is supplied to the inlet of the cylinder head 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 wall of the cylinder head is cooled, and in particular, around the sub-chamber with a high heat load. Since the meat wall part is only air-cooled, the cooling becomes insufficient and it overheats. Moreover, this cylinder head liquid cooling device is one in which a cooling liquid passage that passes through the vicinity of a sub chamber having a high heat load is formed, and a cooling liquid jacket is not formed around the sub chamber. The high heat generated in the room cannot be absorbed promptly. 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.

The present invention has been made in view of the above circumstances, and is a cylinder head of a sub-compartment type engine that is small in size, light in weight, and has sufficiently high cooling performance in a sub-compartment type engine with low combustion noise and clean combustion exhaust gas. An object of the present invention is to provide a liquid cooling device.

<< Means for Solving the Problems >> In order to achieve the above object, the present invention forms a cooling liquid jacket 9 around the sub chamber 22 formed in the cylinder head 8 of the engine 1 and Vice room
A cooling air passage 32 for allowing cooling air to pass is formed in a portion other than the periphery of 22 and the cooling fan 30 and the air guide case 31 are provided in the engine 1.
Are arranged so that the cooling air generated by the cooling fan 30 is guided to the cooling air passage 32 by the air guide case 31, while the inlet 9a of the cooling liquid jacket 9 is located below the cooling liquid jacket 9. While opening, the outlet 10 is formed in the upper part of the cooling liquid jacket 9,
The outlet 10 of the cooling liquid cooler 11 through the cooling liquid jacket 9
It is characterized in that it is communicated with the entrance 9a.

<< Operation >> According to the above configuration, since the cooling liquid circulates in the cooling liquid jacket 9 formed around the sub chamber 22, the sub chamber 22 having a particularly high heat load is strongly cooled from the surroundings by the cooling liquid.
Never overheat. As a result, the thermal stress in the cylinder head 8 is reduced, cracks are less likely to occur, there is almost no thermal strain, and gas leakage from the joint surface with the cylinder block 17 does not occur.

The cooling air generated by the cooling fan 30 is supplied to the portion of the cylinder head 8 other than the periphery of the sub chamber 22 while being guided by the air guide case 31, and this portion is cooled by the cooling air passing through the cooling air passage 32. Air cooled. Therefore, in cooling the cylinder head 8, the amount of absorbed heat of the cooling liquid is much smaller than that in the case where the entire cylinder head 8 is liquid-cooled while strongly cooling the sub-chamber 22 which is particularly high in temperature from the surroundings. As a result, the amount of cooling liquid required for cooling the cylinder head 8 can be reduced, and the cooling liquid cooler 11 can be downsized.

In addition, the inlet 9a of the cooling liquid jacket 9 is opened in the lower portion of the cooling liquid jacket 9, and its outlet 10 is formed in the upper portion of the cooling liquid jacket 9, and this outlet 10 is connected to the oil cooler. The cooling liquid heated in the sub chamber 22 having a high heat load rises in the cooling liquid jacket 9 by the action of natural convection, and the cooling liquid having a high temperature does not stay in the cooling liquid jacket 9 and the cooling liquid cooler It flows smoothly to the 11 side.

Further, since the cooling liquid jacket 9 is formed around the sub chamber 22, the cooling liquid in the cooling liquid jacket 9 is heated by the combustion heat of the sub chamber 22 at the time of cold start of the engine, for example, in the cold season. 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.

<< Example >> Hereinafter, the Example of this invention is described based on drawing.

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. A supply pump 5 is attached. 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 12 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 is connected.
Is communicated with the oil pan 3 via the push rod insertion chamber 14.

The cooling oil supply passage 7 is connected to an inlet passage 15 that communicates in order,
It is composed of a cylinder oil jacket 16 and an introduction passage 18. A starting end portion of the inlet passage 15 is branched and connected in the middle of the lubricating oil supply passage 6, and an end portion thereof is connected to a bottom portion of the cylinder oil jacket 16. Cylinder oil jacket 16 includes cylinder 17a and push rod insertion chamber 14
Is formed between the cylinder block 17 and the cylinder head 8, and the upper end thereof 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. The middle portion of the introduction passage 18 is the cylinder oil jacket 16
Is formed so as to pass through the valve-to-valve portion 21 between the intake valve hole 19 and the exhaust valve hole 20 along the wall surface (lower wall) 8a of the cylinder head 8 on the cylinder block side.

By the way, the cylinder head 8 has a crankshaft 23
Intake valve hole 19 and exhaust valve hole formed side by side in the axial direction of the
20, an intake port 24 communicating with the intake valve hole 19, and an exhaust valve hole
Exhaust port 25 communicating with 20, intake valve hole 19 and exhaust valve hole
A sub-chamber 22 arranged on one lateral side of 20 and a push rod insertion chamber arranged on the other lateral side of intake valve hole 19 and exhaust valve hole 20.
14 and are provided. The oil jacket 9 is formed around 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.

In addition, the front end wall 2b of the crankcase 2 of the engine 1
The front end of the crank shaft 23 is projected on the front side of the cooling fan 30, and the cooling fan 30 is fixed to the front end of the crank shaft 23.
The cooling air generated by this cooling fan 30 is applied to the cylinder block 1
The air guide case 31 guiding 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 between the peripheral walls of the intake port 24 and the exhaust port 25 and the push rod insertion chamber 14, and the cooling air guided by the air guide case 31 passes from the front to the rear through the cooling air passage 32. Intake port 24 and exhaust port 25 while flowing to
Are formed so as to be in contact with both peripheral walls of the.

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, while passing through the introduction passage 18, the intervalve portion
21 is cooled strongly. 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. Returned to the oil pan 3.

On the other hand, the cooling air generated by the cooling fan 30 is guided by the wind guide case 31 to 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 peripheral surface of the cylinder block 17 to cool the entire cylinder block 17, and the cooling air guided to the front surface of the cylinder head 8 cools the cooling air of the cylinder head 8. It passes through the passage 32 and comes into contact with the peripheral walls of the intake port 24 and the exhaust port 25 to cool them. Also, the cooling air guided by the oil cooler 11 is
Cooling the lubricating oil that circulates in the oil cooler 11 by blowing through 11 from the bottom to the top.

In this way, the oil jacket 9 is formed around the sub chamber 22 of the cylinder head 8 and the lubricating oil circulates in the oil jacket 9. Therefore, the periphery of the sub chamber 22 which is apt to reach a high temperature is strongly cooled. , Never 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 surroundings of the sub chamber 22 is air-cooled by the cooling air passing through the cooling air passage 32, the lubricating oil circulating in the oil jacket 9 does not heat 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 absorbed by the lubricating oil is small, the oil cooler 11 can be downsized.

Further, the lubricating oil in the oil jacket 9 is heated by the sub chamber 22 having a high heat load, and since the volume of the oil jacket 9 is small, the lubricating oil is likely to quickly reach a high temperature. However, since the lubricating oil enters the oil jacket 9 through the lower inlet 9a and exits through the upper outlet 10 of the oil jacket 9 to the outside of the oil jacket 9, the lubricating oil heated to a high temperature is affected by natural convection. The oil rises in the oil jacket 9 and smoothly flows out to the oil cooler 11 side without staying in the oil jacket 9. As a result, the cooling effect of the lubricating oil in the oil jacket 9 is not impaired, and the sub chamber 22 can be cooled more strongly.

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, since the cooling air passage 32 is formed so that the cooling air comes into contact with the peripheral walls of the intake port 24 and the exhaust port 25,
The cooling air comes into contact with the intake port 24 to cool the intake air flowing therein, and comes into contact with the exhaust port 25 to cool the exhaust port 25. As a result, the heat transfer from the exhaust port 25 to the intake port 24 is suppressed, the intake air is suppressed from being heated by the exhaust heat, the intake air is kept cool, and the filling efficiency is increased.
The engine output is increased.

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

<< Effects of the Invention >> The present invention has the following effects because it is configured and operates as described above.

(B) Since the cooling liquid passing through the cooling liquid jacket strongly cools the sub-chamber, which has a particularly high temperature, from the surroundings, it only absorbs the heat around the sub-chamber.
The amount of heat absorbed is much less than when cooling the entire cylinder head.

As a result, the amount of cooling liquid required for cooling the cylinder head can be reduced, the weight of the cylinder head can be reduced, the cooling liquid cooler can be downsized, and the entire engine can be downsized.

(B) Since the inlet of the cooling liquid jacket is opened in the lower part of the cooling liquid jacket, the outlet is formed in the upper part of the cooling liquid jacket, and the outlet of the cooling liquid jacket is in communication with the cooling liquid cooler. The cooling liquid heated in the high-temperature sub chamber rises in the cooling liquid jacket by the action of natural convection, and the high temperature cooling liquid smoothly flows out to the cooling liquid cooler side without staying in the cooling liquid jacket. it can.

As a result, while cooling the sub chamber having a high heat load with a small amount of cooling liquid, it is possible to prevent the decrease in cooling efficiency caused by staying in the cooling liquid jacket and strongly cool the cylinder head. .

(C) Since the cooling liquid jacket is formed around the sub-chamber while the amount of cooling liquid is small, it is possible to strongly cool the sub-chamber with a particularly high heat load from the surroundings by the cooling liquid, and to overheat it. There is no.

As a result, the cylinder head has less thermal stress, is less likely to crack, has excellent durability, and has almost no thermal strain, so gas leakage does not occur from the joint surface with the cylinder block, and output reduction can be prevented. .

(D) Moreover, since a small-capacity cooling liquid jacket is formed around the sub-chamber, the cooling liquid in the cooling liquid jacket is rapidly heated by the combustion heat of the sub-chamber during engine cold start, for example, during the cold season. It Therefore, even if the amount of the cooling liquid is small, direct cooling of the sub-chamber by low-temperature cooling air can be eliminated, and the sub-chamber can be kept warm by the cooling liquid in the cooling liquid jacket, thereby preventing the sub-chamber from being overcooled.

As a result, shorten the warm-up time after starting the engine,
The operation can be started promptly.

[Brief description of drawings]

FIG. 1 is a vertical sectional rear view of a main part of a sub-chamber type 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, 8 ... Cylinder head, 9 ... Coolant jacket, 9a ... Coolant jacket inlet, 10 ... Coolant jacket outlet, 11 ... Coolant cooler, 22 ... Subchamber, 30 …… Cooling fan, 31 …… Wind guide case, 32 …… Cooling air passage.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F02F 1/36 F02F 1/36 A

Claims (1)

(57) [Claims] 1. A cooling liquid jacket (9) is formed around a sub-chamber (22) formed in a cylinder head (8) of an engine (1), and the sub-chamber (22) of the cylinder head (8) is formed.
Cooling air passages (32) that allow cooling air to pass through parts other than around the
The cooling fan (30) and the air guide case (31) are arranged in the engine (1), and the cooling air generated by the cooling fan (30) is transferred to the cooling air passage by the air guide case (31). While being configured to guide to the (32), the inlet (9a) of the cooling liquid jacket (9) is opened to the lower part of the cooling liquid jacket (9) and the outlet (1
0) is formed in the upper part of the cooling liquid jacket (9), and the outlet (10) of this cooling liquid jacket (9) is introduced through the cooling liquid cooler (11) into the inlet (9a) of the cooling liquid jacket (9).
Cylinder head liquid cooling device for a sub-chamber engine, which is characterized by being communicated with.