JP2003097265A - Exhaust port cooling device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust port cooling device capable of suppressing the lowering of an exhaust gas temperature in an exhaust port at engine start to elevate a catalyst temperature and also of sufficiently cooling the exhaust port after warming up. SOLUTION: During the catalyst temperature is low at engine start, an exhaust side cooling water jacket 6 is separated from a cooling water circulation system by closing the fourth and fifth valves 9 and 10, and such a state that air can be introduced into the jacket 6 is prepared by opening a third valve 19. Further, the water in the jacket 6 is discharged into a discharge water tank 20 by opening a second valve 22 to replace water with air in the jacket 6. When the catalyst temperature is substantially elevated, cooling water is poured into the jacket 6 by closing the second valve 22 and alternatively opening a first valve 17 and then, the first and third valves 17 and 19 are closed in such a state that the jacket 6 is filled with water. Subsequently, the jacket 6 is connected to the cooling water circulation system by opening the fourth and fifth valves 9 and 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust port cooling device for an internal combustion engine, and more particularly to an exhaust port cooling device suitable for raising the temperature of a catalyst at the time of starting.

[0002]

2. Description of the Related Art Conventionally, as an exhaust port cooling device for an internal combustion engine, JP-A-5-133225 and JP-A-6-63225 have been used.
There was one disclosed in Japanese Patent No. 185404.
In Japanese Patent Laid-Open No. 5-133225, a port liner having a heat insulating layer is fitted in an exhaust port to block heat input from a cylinder head or exhaust gas to a cooling liquid passage formed in the port liner to cool the port. A cooling device is disclosed in which the cooling liquid in the liquid passage is provided only for cooling the valve seat.

Japanese Patent Laid-Open No. 6-185404 discloses that
A minute gap that functions as an air heat insulating layer is formed between the outer peripheral surface of the exhaust liner fitted to the exhaust port and the inner peripheral surface of the exhaust port, and the minute gap achieves heat insulation at the time of starting and continuous drive. At times, there is a disclosure of a configuration in which the minute gap disappears due to the thermal expansion in the radial direction of the exhaust liner, the heat transfer property increases, and the excessive temperature rise of the exhaust gas is suppressed.

Further, a cooling device having a construction in which a cooling chamber formed in a liner is exchanged with air and water has been disclosed in Japanese Utility Model Publication No. 5-089.
It is disclosed in Japanese Patent No. 835. Actual Kaihei 5-089
In Japanese Patent No. 835, the cooling chamber formed on the outer circumference of the cylinder liner is partitioned into an upper cooling chamber and a lower cooling chamber, and cooling water is introduced into the lower cooling chamber by a cooling water pump during high load operation. At the time of low load operation, air is introduced into the lower cooling chamber by an air pump.

[0005]

By the way, at the time of starting, it is required to quickly raise the temperature of the catalyst interposed in the exhaust passage of the engine to the activation temperature so as to exert the purification performance of the catalyst. Requires the exhaust gas to be introduced into the catalyst at a temperature as high as possible. However, the exhaust port structure disclosed in Japanese Unexamined Patent Publication No. 5-133225 is intended to improve knock resistance during high load operation, and suppresses a decrease in exhaust gas temperature during low load operation. However, it is not a structure capable of increasing the temperature of the catalyst.

Further, in the one disclosed in Japanese Patent Laid-Open No. 6-185404, the exhaust port is insulated by the air layer during the low load operation to suppress the decrease of the exhaust gas temperature. The configuration is such that a minute gap is secured by the difference in thermal expansion, and there is a problem that it is difficult to secure a sufficient gap due to the difference in thermal expansion of the metal-based material applied to the high temperature of the exhaust system.

Further, during high load operation, a sufficient cooling effect cannot be obtained unless the cylinder head and the liner are brought into contact with each other. Therefore, it is necessary to set the temperature at which they are brought into contact with each other at a low temperature. Under the conditions, there is a problem that the difference in thermal expansion causes stress in the cylinder head, which causes fatigue and breakage of the cylinder head. Further, as a configuration for switching between heat insulation and cooling, the above-mentioned actual Kaihei 5-0898 is used.
As disclosed in Japanese Patent Laid-Open No. 35-35, there is a configuration in which cooling water and air are exchanged, but this is a configuration that prevents deterioration of fuel efficiency during low load operation by maintaining the temperature of the cylinder liner at an appropriate temperature. In addition to the structure that raises the exhaust temperature, when replacing the air and water in the cooling chamber, an air pump is required in addition to the normal cooling water pump, which raises the problem of increased system cost. It was

The present invention has been made in view of the above problems, and does not generate stress in the cylinder head.
Exhaust port of an internal combustion engine capable of reliably suppressing excessive temperature rise of exhaust gas during high load operation and suppressing decrease of exhaust gas temperature during low load operation to promote temperature rise of catalyst An object is to provide a cooling device.

Another object of the present invention is to enable the exhaust port cooling device for an internal combustion engine to be constructed at low cost.

[0010]

Therefore, an exhaust port cooling device for an internal combustion engine according to a first aspect of the present invention is provided with a jacket or liner capable of exchanging air and water in an exhaust port portion of a cylinder head of the internal combustion engine. Are independently formed. According to such a configuration, the inside of the jacket or liner independently formed in the exhaust port is replaced with air and water, and functions as an air heat insulating layer when air is contained, and has a cooling effect when water is contained. can get.

According to a second aspect of the present invention, a water supply tank is provided at a position higher than the cylinder head and a drainage tank is provided at a position lower than the cylinder head, and the jacket or liner and the water supply tank / drainage tank are provided. Based on the difference in height, the drainage from the jacket or liner and the water injection to the jacket or liner are performed.

According to this structure, the water tank and the drain tank are provided above and below the cylinder head, and water is injected into the lower jacket or liner from the water tank at the higher position, and the water in the jacket or liner is injected. Is discharged to a drainage tank located at a lower position so that the inside of the jacket or liner becomes air. According to the third aspect of the invention, the water inlet for the jacket or liner and the air outlet and drain for the air from the jacket or liner are switched according to the inclination of the engine.

According to this structure, when the inclination of the engine changes on a slope or the like, and the highest position or the lowest position of the jacket or liner changes, the water inlet and the air or water outlet correspond to the change. Switch.
According to the invention of claim 4, from the time of starting the engine until the temperature of the catalyst installed in the exhaust passage of the engine reaches a predetermined temperature,
The inside of the jacket or liner is filled with air, and after reaching the predetermined temperature, the inside of the jacket or liner is replaced with water.

According to this structure, when the temperature of the catalyst is low immediately after the engine is started, the inside of the jacket or liner is made to be air, thereby functioning as an air heat insulating layer and suppressing a decrease in exhaust gas temperature at the exhaust port. On the other hand, when the catalyst temperature becomes sufficiently high, the inside of the jacket or liner is replaced with water from the air to cool the exhaust port.

According to a fifth aspect of the present invention, there is provided an exhaust port cooling device for an internal combustion engine, wherein a jacket or liner independently formed in an exhaust port portion of a cylinder head of the internal combustion engine, and the jacket or liner and a water circulation path. A circulation switching valve for switching between separation and connection with the water supply tank, a water supply tank arranged at a position higher than the cylinder head, a water supply pipe communicating the water supply tank with a lower position of the jacket or liner, and the water supply pipe. An interposed water supply valve, an air pipe communicating with a higher position of the jacket or liner, extended to a position higher than the maximum water level of the water supply tank and then opened, and an air pipe interposed between the air pipe and the pipe. Air valve,
A drainage tank arranged at a position lower than the cylinder head, a drainage pipe communicating the drainage tank with a lower position of the jacket or liner, a drainage valve interposed in the drainage pipe, and the circulation switching valve. With the circulation path and the jacket or liner separated from each other, the water supply valve is closed, the air valve is opened, the drain valve is opened, and the drain control means for making air in the jacket or liner, and the circulation. With the switching valve separated from the circulation path, the water supply valve is opened, the air valve is opened, the drain valve is closed, and water is injected while expelling air from the jacket or liner, and then the water supply valve and the air. After closing the valve, a water circulation control means for connecting the circulation path and the jacket or liner by the circulation switching valve is included. It was.

According to this structure, the circulation switching valve separates the circulation path from the jacket or liner of the exhaust port, and the air valve is opened and the drain valve is opened while water is confined in the jacket or liner. Then,
At the same time as the water is drained to the lower drainage tank via the drainage pipe, it is replaced by the introduction of air via the air pipe.

Further, as described above, when the water supply valve is opened from the state where the inside of the jacket or liner is air, the water from the water supply tank at a higher position is supplied to the inside of the jacket or liner through the water supply pipe. It is injected from a low position and is pushed up by this water so that the air is discharged via an air pipe connected to a high position. According to a sixth aspect of the invention, a supply / discharge port switching valve for switching between a connection position of the air pipe with respect to the jacket or liner and a connection position of the drain pipe and the water supply pipe with respect to the jacket or liner, and an inclination of the engine. And a supply / discharge port switching control unit for controlling the supply / discharge port switching valve according to the above.

According to this structure, the connection positions of the air pipe, the drain pipe and the water supply pipe to the jacket or liner are switched according to the inclination of the engine, and the air pipe is connected to a higher position of the jacket or liner, The pipe and water supply pipe should be connected to the lower part of the jacket or liner. In the invention according to claim 7, from the time of starting the engine until the temperature of the catalyst installed in the exhaust passage of the engine reaches a predetermined temperature, the inside of the jacket or liner is made air by the drainage control means, and the temperature is raised to the predetermined temperature. After the temperature is reached, the water circulation control means is operated to provide catalyst temperature control means for circulating water in the jacket or liner.

According to this structure, when the temperature of the catalyst is low immediately after the engine is started, the inside of the jacket or liner is made to function as an air heat insulating layer to prevent the temperature of the exhaust gas at the exhaust port from lowering, while at the same time reducing the temperature of the catalyst. When the temperature becomes sufficiently high, the inside of the jacket or liner is replaced with water from the air to cool the exhaust port.

In the invention according to claim 8, the air pipe is
It is configured to be opened in the water supply tank, a replenishment switching valve for switching supply / stop of water to the circulation path in the drainage tank, a water level detection means for detecting the water level in the water supply tank, the jacket or In a state where water is circulated in the liner, when the water level in the water supply tank detected by the water level detecting means is below a predetermined level, the replenishment switching valve supplies water in the drainage tank to the circulation path. , Open the air valve installed in the air pipe,
Replenishment control means for replenishing a part of the water circulated in the jacket or liner to the water supply tank.

According to this structure, the water level in the water supply tank decreases, and the water level in the drainage tank increases. Therefore, when the water level in the water supply tank decreases, the water in the drainage tank is circulated to the circulation path. By supplying it, new drainage from the jacket or liner is possible, and part of the water circulated in the jacket or liner is supplied through the air pipe that functions as an air outlet / intake port during water supply / drainage. Let the water tank replenish.

[0022]

According to the first aspect of the present invention, the inside of the jacket or liner independently provided in the exhaust port is
By switching between water and air, there is an effect that it is possible to switch between a state in which the temperature of exhaust gas is suppressed from being lowered by the heat insulation of the air and the temperature of the catalyst can be increased, and a state in which the exhaust port portion is actively cooled.

According to the second aspect of the invention, water is injected into the jacket or liner and drained from the jacket or liner based on the height difference between the water supply tank / discharge tank and the jacket or liner. There is an effect that it is possible to suppress an increase in system cost without requiring a pump or the like. Claim 3
According to the described invention, even if the engine is tilted and the high part and the low part of the jacket or liner are exchanged with each other, it is possible to prevent air from being mixed into the water or remaining of the water without being completely drained. There is an effect that can be done.

According to the fourth aspect of the invention, since the inside of the jacket or liner provided in the exhaust port portion is insulated with air until the catalyst temperature rises sufficiently, the temperature of the exhaust gas passing through the exhaust port is increased. While suppressing the decrease, it is possible to accelerate the temperature rise of the catalyst, on the other hand, after the catalyst temperature has become sufficiently high, there is an effect that it is possible to perform the necessary cooling by using water in the jacket or liner. is there.

According to the fifth aspect of the present invention, depending on the combination of the open / closed states of various valves, the height difference between the water supply / exhaust tank and the jacket or liner provided at the exhaust port is based on the jacket or liner. Water can be poured without mixing air, and water can be drained without leaving water from the jacket or liner, and the jacket or liner can be air-insulated and cooled with water as a refrigerant. In addition, there is an effect that switching can be surely performed with a simple configuration.

According to the sixth aspect of the present invention, even if the engine is tilted and the high part and the low part of the jacket or liner are interchanged, the connection of the air pipe, the drainage pipe and the water supply pipe is performed corresponding to the interchange. Since the position is changed, there is an effect that it is possible to prevent air from being mixed into the water due to the inclination of the engine, and to prevent the water from remaining without being completely drained.

According to the seventh aspect of the present invention, water is discharged from the jacket or liner provided in the exhaust port portion to air by controlling the opening and closing of various valves until the catalyst temperature rises sufficiently. Since the state is maintained and heat insulation is achieved, the temperature drop of the exhaust gas passing through the exhaust port can be suppressed and the temperature rise of the catalyst can be promoted. Since the water in the water supply tank is injected by the opening / closing control and then connected to the circulation path, there is an effect that the water can be circulated in the jacket or the liner to perform necessary cooling.

According to the eighth aspect of the present invention, a state in which water can be newly drained to the drain tank, water can be replenished in the water supply tank, and water can be injected again into the jacket or liner There is an effect that it can be performed by utilizing the circulation by the cooling water pump.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a cooling system of an internal combustion engine including an exhaust port cooling device according to the present invention. On the front side of the internal combustion engine 1, an engine-driven water pump 2 is provided, and the cooling water discharged from the water pump 2 first enters the cylinder block 3 and
A cooling water jacket (not shown) extending in the cylinder row direction with respect to the cylinder block 3 passes from the front side to the rear side and enters the cylinder head 4 from the rear side.

The cylinder head 4 is shown in FIGS.
As shown in, the cooling water jacket 6 on the exhaust port 5 side
And a cooling water jacket 8 on the side of the intake port 7 extend independently of each other in the cylinder row direction, and the cooling water jackets 6, 8 communicate with each other via the fourth valve 9 on the front side. The rear side communicates with the fifth valve 10. The cooling water that has passed through the cylinder block 3 enters the rear end of the cooling water jacket 8 on the intake side.
When 0 is open, part of the water also enters the cooling water jacket 6 on the exhaust side and flows to the front side along the cooling water jackets 6 and 8.

In the state where the fourth valve 9 on the front side is open, the cooling water that has passed through the cooling water jacket 6 on the exhaust side merges into the cooling water jacket 8 on the intake side, and passes through the water outlet 11. , Is supplied to the radiator 12. The cooling water radiated by the radiator 12 enters the thermostat housing 14 via the water inlet 13, and the cooling water from the thermostat housing 14 is supplied to the suction port of the water pump 2.

A water supply tank 15 is arranged above the cylinder head 4, and a water supply pipe 16 connecting the water supply tank 15 and the rear side of the cooling water jacket 6 on the exhaust side is provided with a first water supply valve as a water supply valve. One valve 17 is interposed. still,
When the internal combustion engine 1 is mounted on a vehicle (not shown) and the vehicle is on a substantially horizontal road, the front side is high and the rear side is low. Therefore, the rear side of the cooling water jacket 6 indicates the lowest side of the jacket 6 on a horizontal road.

Further, after being connected to the upper wall of the front end of the exhaust side cooling water jacket 6 and extending to a position higher than the maximum water level of the water supply tank 15, it is opened in the water supply tank 15. The air pipe 18 is provided, and the air pipe 18 is provided with a third valve 19 as an air valve. Further, a drainage tank 20 is provided at a position lower than the cylinder head 4, and the drainage pipe 21 that connects the drainage tank 20 and the bottom of the exhaust side cooling water jacket 6 on the rear side has a second valve as a drainage valve. 22 is interposed.

The bottom of the drainage tank 20 is connected to the suction port side of the water pump 2 via a sixth valve 23 as a replenishment switching valve and a one-way valve 24. FIG. 4 is a simplified view of the above-mentioned configuration, and the first to sixth valves 17, 22, 19, 9, 10, 23 are the control unit 2 incorporating a microcomputer.
The opening / closing control is performed by the switch 5.

FIG. 5 shows a combination of the opening / closing control of each valve by the control unit 25. As shown in FIG. 5 (e), the cooling water is normally circulated in the exhaust side cooling water jacket 6. While maintaining the first valve 17, the second valve 22 and the third valve 19 in the closed state,
By controlling the valve 9 and the fifth valve 10 to open so that the exhaust side cooling water jacket 6 and the intake side cooling water jacket 8 communicate with each other on the rear side and the front side, the cylinder block 3 is supplied to the cylinder head 4. The cooling water is also made to flow into the cooling water jacket 6 on the exhaust side.

At this time, in each of the portions A to G shown in FIG. 4, the inside of the pipe is filled with cooling water. The position G of the air pipe 18 higher than the third valve 19 is lower than the water level of the water supply tank 15. From the normal time when the cooling water is circulated in the exhaust side cooling water jacket 6 as described above, the inside of the exhaust side cooling water jacket 6 can be made to be air, and when the cooling water is replaced with air (drainage control means), First, as shown in (f) of FIG. 5, the fourth and fifth valves 9 and 10 that are normally open are closed to connect the communicating portion between the exhaust side cooling water jacket 6 and the intake side cooling water jacket 8. Exhaust side cooling water jacket 6 by shutting off
Is separated from the cooling water circulation path.

Subsequently, as shown in FIG. 5A, the second and third valves 22 and 19 are opened. When the second valve 22 is opened, the water in the exhaust side cooling water jacket 6 is discharged to the drainage tank 20, and instead, the air enters the exhaust side cooling water jacket 6 via the air pipe 18. Here, since the drain pipe 21 is connected to the lowest position of the exhaust side cooling water jacket 6, all the water in the exhaust side cooling water jacket 6 is discharged, and is enclosed by the first to fifth valves. The inside of the pipe including the exhaust side cooling water jacket 6 is filled with air.

When the inside of the exhaust side cooling water jacket 6 becomes an air layer, the air layer functions as a heat insulating layer, and the exhaust port 5
A decrease in the temperature of the exhaust gas passing through is suppressed. On the other hand, as described above, when the state in which the exhaust side cooling water jacket 6 is in the air layer is changed to the state in which water is normally circulated (water circulation control means), first, (a) in FIG. As shown in, the second valve 22 is closed to shut off the drainage path of the cooling water.

Then, as shown in FIG. 5C, the first
Open valve 17. When the first valve 17 is opened, the cooling water stored in the water supply tank 15 is injected from a lower position in the exhaust side cooling water jacket 6, and the air that has filled the exhaust side cooling water jacket 6 until then is It is expelled upward in the exhaust side cooling water jacket 6 and is discharged through the air pipe 18.

As a result, the exhaust side cooling water jacket 6
All of the inside is filled with water, and finally the inside of the air pipe 18 is filled with water to the same water level as the water supply tank 15. Therefore, subsequently, as shown in FIG. 5D, if the first valve 17 and the third valve 19 are closed, the water injected from the water supply tank 15 is confined. As shown in (e), if the fourth and fifth valves 9 and 10 are opened, the inside of the exhaust side cooling water jacket 6 can be connected to the circulation path without mixing air in the cooling water.

The steps (a) to (d) for replacing the air with the cooling water are switched at preset time intervals. By the way, the sixth valve 23 is maintained in a basically closed state both when the inside of the exhaust side cooling water jacket 6 is air and when it is water, but the water level sensor 26 for detecting the water level in the water supply tank 15 is used. Based on the detection result of the (water level detection means), the control unit 25 having a function as a replenishment control means controls as shown in FIG.

With the cooling water circulated in the cooling water jacket 6 on the exhaust side, the water level sensor 26 is used to supply water to the water tank 15.
When it is detected that the amount of water inside is insufficient, the third valve 19 and the sixth valve 23 are opened, as shown in (e ') of FIG. An insufficient amount of water in the water supply tank 15 indicates an increase in the amount of water in the discharge tank 20, and when the amount of water in the drainage tank 20 is excessive, drainage from the exhaust side cooling water jacket 6 becomes impossible.

Therefore, by opening the sixth valve 23, the cooling water in the discharge tank 20 is discharged and merged with the cooling water circulated by the water pump 2. On the other hand, by opening the third valve 19, the water level in the air pipe 18 rises due to the pressure of the cooling water circulated in the exhaust side cooling water jacket 6, and the cooling water is replenished through the air pipe 18.

As a result of the above replenishing operation, the water level sensor 26
When it is detected that the amount of water in the water supply tank 15 is sufficient, the third valve 19 and the sixth valve 23 are closed to discharge the cooling water in the discharge tank 20 and to the water supply tank 15. Stop supplying cooling water. The one-way valve 24 prevents the backflow of the cooling water toward the inside of the discharge tank 20 when the sixth valve 23 is opened.

When the vehicle equipped with the engine 1 is on a substantially horizontal road surface, the front side of the engine 1 is higher than the rear side, but when the vehicle is on a steep slope, the rear side may be higher. However, at this time, if water and air are normally exchanged as they are, there is a possibility that water and air will not be completely removed and may remain. In order to reliably perform the air / water exchange operation on the steep slope as described above, as shown in FIG.
As a supply / discharge port switching valve for switching the connection destination of No. 1,
The valve 32 may be provided.

As described above, the eighth valve 32 connects the water supply pipe 16 and the drain pipe 21 to the rear side of the engine, and the air pipe 1
8 is connected to the front side of the engine, the water supply pipe 16 and the drain pipe 21 are connected to the front side of the engine, and the air pipe 18
Is connected to the rear side of the engine. The control unit 25 having a function as a supply / discharge port switching control means determines which of the front side and the rear side of the engine is higher, based on the detection result of the inclination sensor 33 which detects the inclination of the vehicle (engine). .

In a normal state where the front side is high,
The water supply pipe 16 and the drain pipe 21 are connected to the rear side of the engine,
The eighth valve 32 is controlled so that the air pipe 18 is connected to the front side of the engine, and conversely, when the rear side is high, the water supply pipe 16 and the drain pipe 21 are connected to the front side of the engine, The eighth valve 32 is controlled so that 18 is connected to the rear side of the engine.

As described above, the control unit 25
Controls the combination of the open / closed states of each valve to replace the inside of the exhaust side cooling water jacket 6 with air and cooling water. The replacement control is performed by the catalyst 28 installed in the exhaust pipe 27 of the internal combustion engine 1. (See FIG. 2). The flow chart of FIG. 8 shows the details of the replacement control (catalyst temperature control means) based on the temperature of the catalyst 28. In step S1, the ignition switch is turned off.
If it is determined that the temperature is N, the process proceeds to step S2, and the catalyst temperature sensor 29 (FIG. 2) for detecting the temperature of the catalyst 28 is used.
It is determined whether or not the detection result of (see) exceeds a preset reference temperature.

When the catalyst temperature sensor 29 is not provided, it is determined whether or not the detection result of the water temperature sensor 30 which detects the cooling water temperature of the engine 1 exceeds the reference temperature. In step S2, when the temperature of the catalyst 28 (or cooling water temperature) exceeds the reference temperature, that is, when restarting immediately after the engine is stopped, the process proceeds to step S6, and exhaust side cooling is performed while the engine is stopped. The state in which the water in the water jacket 6 is kept as is is maintained so that the water is circulated in the exhaust side cooling water jacket 6 from the time of engine start.

On the other hand, when it is determined in step S2 that the temperature of the catalyst 28 (or the cooling water temperature) is lower than the reference temperature, the process proceeds to step S3 and the inside of the exhaust side cooling water jacket 6 is changed from water to air. Replace with.
If the inside of the exhaust side cooling water jacket 6 is made of air, the temperature reduction of the exhaust gas flowing through the exhaust port 5 is suppressed by the adiabatic effect of this air, and the temperature of the exhaust gas flowing into the catalyst 28 can be increased, so that the catalyst It is possible to raise the temperature of 28.

When the inside of the exhaust side cooling water jacket 6 is replaced with air, it is determined in step S4 whether or not the temperature of the catalyst 28 (or the cooling water temperature) exceeds the reference temperature. Then, until the temperature of the catalyst 28 (or the cooling water temperature) exceeds the reference temperature, the inside of the exhaust side cooling water jacket 6 is kept in air, and the temperature of the catalyst 28 (or the cooling water temperature) exceeds the reference temperature. Then, the process proceeds to step S5.

The exhaust side cooling water jacket 6 may be filled with air for a predetermined time from the start, and then the exhaust side cooling water jacket 6 may be replaced with air. In step S5, the inside of the exhaust side cooling water jacket 6 is replaced with water from the air, thereby cooling the cylinder head 4 and avoiding an excessive rise in temperature.

After that, the routine proceeds to step S6, where the state in which water is circulated in the exhaust side cooling water jacket 6 is continued while the engine is operating, and the respective valves are maintained in the normal water circulation state even after the engine is stopped. , So that water is retained in the exhaust side cooling water jacket 6. Then, at the time of restart, whether to discharge the water in the exhaust side cooling water jacket 6 is selected based on the temperature of the catalyst 28 (or the cooling water temperature).

Incidentally, when the engine 1 is stopped, the water in the exhaust side cooling water jacket 6 is unconditionally discharged, and at the time of restart, the water is injected into the exhaust side cooling water jacket 6 after the catalyst temperature becomes high. Can be Further, the temperature condition is monitored while the engine 1 is stopped, and water is kept in the exhaust side cooling water jacket 6 until the temperature becomes low, and after the temperature becomes low, the exhaust side cooling water jacket 6 It is also possible to have a structure in which the water inside is discharged.

Further, in the above-described embodiment, the inside of the cooling water jacket 6 provided around the exhaust port 5 is replaced with water and air. However, a liner is fitted to the exhaust port 5 to increase the wall thickness of the liner. The annular gap formed inside may be replaced with air and water. In the above description, the first to sixth valves are electronically controlled, but the first valve is a thermo valve that opens and closes according to the temperature of the cooling water.
~ It is also possible to constitute the sixth valve.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cooling system of an internal combustion engine including an exhaust port cooling device according to the present invention.

2 is a cross-sectional view of a cylinder head of the internal combustion engine shown in FIG.

FIG. 3 is a state diagram showing a flow of cooling water in the cylinder head.

FIG. 4 is a configuration diagram of valves and piping of the exhaust port cooling device in the embodiment.

FIG. 5 is a diagram showing a correlation between a combination of valve open / closed states and a state in the exhaust side cooling water jacket.

FIG. 6 is a diagram showing a combination of opening and closing states of valves in a replenishing operation for a water supply tank.

FIG. 7 is a configuration diagram of valves and piping of an exhaust port cooling device that performs switching according to the inclination of the vehicle.

FIG. 8 is a flowchart showing water / air exchange control based on the catalyst temperature.

[Explanation of symbols]

1 ... Internal combustion engine 2 ... Water pump 3 ... Cylinder block 4 ... Cylinder head 5 ... Exhaust port 6 ... Exhaust side cooling water jacket 7 ... Intake port 8 ... Inlet side cooling water jacket 9 ... 4th valve 10 ... Fifth valve 12 ... radiator 15 ... Water tank 16 ... Water pipe 17 ... First valve 18 ... Air tube 19 ... Third valve 20 ... Drainage tank 21 ... Drainage pipe 22 ... Second valve 23 ... 6th valve 24 ... One way valve 25 ... Control unit 26 ... Water level sensor 28 ... Catalyst 29 ... Catalyst temperature sensor 30 ... Water temperature sensor 33 ... Inclination sensor

Claims (8)

[Claims] 1. An exhaust port cooling device for an internal combustion engine, characterized in that a jacket or liner capable of switching between air and water is independently formed in an exhaust port portion of a cylinder head of the internal combustion engine. 2. A water supply tank is provided at a position higher than the cylinder head, and a drainage tank is provided at a position lower than the cylinder head, based on a height difference between the jacket or liner and the water supply tank / drainage tank. ,
The exhaust port cooling device for an internal combustion engine according to claim 1, wherein drainage from the jacket or liner and water injection into the jacket or liner are performed. 3. The internal combustion engine according to claim 2, wherein an inlet for water to the jacket or liner, an outlet for discharging air from the jacket or liner, and a drain port are switched according to the inclination of the engine. Exhaust port cooling system for engines. 4. The inside of the jacket or liner is filled with air from the time when the engine is started until the temperature of the catalyst inserted in the exhaust passage of the engine reaches a predetermined temperature, and after the temperature reaches the predetermined temperature, the inside of the jacket or liner The exhaust port cooling device for an internal combustion engine according to claim 1, wherein the exhaust gas is replaced with water. 5. A jacket or liner independently formed in an exhaust port portion of a cylinder head of an internal combustion engine, a circulation switching valve for switching separation / connection between the jacket or liner and a water circulation path, and the cylinder head. A water supply tank disposed at a higher position, a water supply pipe communicating the water supply tank with a lower position of the jacket or liner, a water supply valve interposed in the water supply pipe, and a higher position of the jacket or liner. And an air valve that is opened after being extended to a position higher than the maximum water level of the water supply tank and then opened, an air valve interposed in the air pipe, and a position lower than the cylinder head. A drainage tank, a drainage pipe communicating the drainage tank with a lower position of the jacket or liner, a drainage valve interposed in the drainage pipe, and the circulation. A drainage control means for closing the water supply valve, opening the air valve, and opening the drainage valve in a state in which the circulation path and the jacket or liner are separated by a ring switching valve to make air in the jacket or liner. In a state of being separated from the circulation path by the circulation switching valve, the water supply valve is opened, the air valve is opened, the drain valve is closed, and water is injected while expelling air from the jacket or liner, and then the water supply is performed. An exhaust port cooling device for an internal combustion engine, comprising: a water circulation control means for connecting a circulation path and the jacket or liner by the circulation switching valve after closing the valve and the air valve. 6. A supply / discharge port switching valve for switching between a connection position of the air pipe with respect to the jacket or liner and a connection position of the drainage pipe and the water supply pipe with respect to the jacket or liner, and depending on the inclination of the engine. The exhaust port cooling device for an internal combustion engine according to claim 5, further comprising: a supply / discharge port switching control unit that controls the supply / discharge port switching valve. 7. The inside of the jacket or liner is made air by the drainage control means from the time of starting the engine until the temperature of the catalyst inserted in the exhaust passage of the engine reaches a predetermined temperature,
The exhaust port of an internal combustion engine according to claim 5 or 6, further comprising: a catalyst temperature control unit that operates the water circulation control unit after the temperature reaches the predetermined temperature to circulate water in the jacket or liner. Cooling system. 8. The air pipe is configured to be opened in the water supply tank, and a replenishment switching valve that switches supply / stop of water in a circulation path in the drainage tank, and a water level in the water supply tank. Water level detection means for detecting, and in a state where water is circulated in the jacket or liner, when the water level in the water supply tank detected by the water level detection means is below a predetermined level, the drain tank by the replenishment switching valve While supplying the water in the circulation path,
6. A replenishment control unit that opens an air valve provided in the air pipe to replenish a part of the water circulated in the jacket or the liner to the water supply tank. An exhaust port cooling device for an internal combustion engine according to any one of items 1 to 7.