JPH06173680A - Cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce cooling loss without lowering the air density of air sucked into the combustion chamber of an internal combustion engine in a cooling device for the internal combustion engine which jets cooling water onto the outer wall of the cylinder of the internal combustion engine to cool the internal combustion engine. CONSTITUTION:A cylinder water jacket 4 is provided between a cylinder block 1 and a cylinder liner 2 in an internal combustion engine. A cylinder head is provided with a combustion chamber water jacket 13 located on the upper part of a combustion chamber 6 together with an intake water jacket 11 and an exhaust water jacket 12. The cylinder water jacket 4 and the combustion chamber water jacket 13 are provided with cooling water injection valves 14 to 16. ECU 17 closes the cooling water injection valves 14 to 16 on a basis of the detection signal of a crank angle sensor 23 while explosion and expansion processes are carried out in each cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for an internal combustion engine, and more particularly, to cooling the internal combustion engine by injecting cooling water to the outer wall of a cylinder forming a combustion chamber in each cylinder of the internal combustion engine. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, there has been known a cooling device for an internal combustion engine, which secures a high cooling efficiency by injecting cooling water to the cylinder outer wall of each cylinder constituting a combustion chamber of the internal combustion engine (Japanese Patent Laid-Open No. 63-63). No. 246409).

According to the apparatus described in the above publication, cooling water is jetted toward the outer wall of the cylinder in the water jacket provided in the internal combustion engine. The injected cooling water takes heat from the outer wall of the cylinder to be vaporized, and flows out of the water jacket along with the heat generated in the internal combustion engine. Then, the heat taken from the internal combustion engine by being cooled by a radiator or the like is released to the atmosphere and liquefied, and again flows into the water jacket by the water pump.

That is, in the internal combustion engine cooling device described in the above publication, the internal combustion engine is cooled by utilizing the heat of vaporization of the cooling water, and effective cooling can be performed with a small amount of cooling water. Therefore, according to the device described in the above publication, the entire cooling device and the radiator can be downsized, and the fuel consumption can be improved by reducing the weight of the vehicle.

[0005]

The cooling capacity of the cooling device for an internal combustion engine is such that the air-fuel mixture supplied to the internal combustion engine does not become overheated and the cooling loss in the internal combustion engine does not unduly increase. Must be set.

That is, when the cooling capacity is insufficient,
The temperature of the entire internal combustion engine rises excessively. As a result, the air taken into the combustion chamber of the internal combustion engine expands, and the air density in the combustion chamber decreases. Then, sufficient combustion cannot be performed in the combustion chamber, and the output of the internal combustion engine decreases.

Further, in a state where the cooling capacity is excessive and an unreasonably large amount of energy is consumed as cooling loss, the combustion pressure generated by the combustion energy of the fuel decreases, and mechanical energy suitable for the burned fuel is taken out. Cannot be achieved, and the output of the internal combustion engine is reduced.

Therefore, in the above-mentioned conventional apparatus, the cooling capacity, that is, the cooling water injected to the outer wall of the cylinder, is a balance point between the output reduction due to the heating of the intake air and the output reduction due to the cooling loss of the internal combustion engine. The flow rate of is set.

However, the cooling loss in the internal combustion engine is a problem because the combustion energy of the fuel is not properly converted into mechanical energy as described above. on the other hand,
The combustion energy of the fuel is generated in the internal combustion engine mainly in the explosion / expansion process in each cylinder.
No energy to be converted into mechanical energy is generated in the intake and compression processes.

That is, when cooling the internal combustion engine, if the cooling capacity is lowered only while the explosion / expansion process is being executed for each cylinder, the energy that can be converted into mechanical energy will be lost as a cooling loss. It is possible to significantly reduce the amount of energy lost.

On the other hand, the air density of the intake air in the combustion chamber decreases because the temperature of the internal combustion engine is high when the intake stroke is executed in each cylinder. Therefore, as long as the temperature of the internal combustion engine during the intake stroke can be set low, no problem will occur even if the temperature of the internal combustion engine during the explosion / expansion stroke is high.

That is, in the case of cooling the internal combustion engine, the cooling capacity is low while the explosion / expansion process is executed for each cylinder, and while the other exhaust, intake, and compression processes are executed. If the cooling capacity is kept high, it is possible to reduce the cooling loss while setting the density of the intake air to a higher level.

However, the above-described conventional cooling device for an internal combustion engine is configured such that the cooling water is injected into all cylinders uniformly and at a constant injection amount, as described above. It is not possible to change the cooling capacity depending on the known process.

The present invention has been made in view of the above points, and the cooling water according to the process executed in each cylinder is provided on the outer peripheral wall of each cylinder constituting the internal combustion engine. An object of the present invention is to provide a cooling device for an internal combustion engine, which can reduce cooling loss without lowering the air density of the air taken into the combustion chamber of the internal combustion engine by injecting.

[0015]

SUMMARY OF THE INVENTION The above-mentioned problem is solved in an internal combustion engine cooling device for cooling an internal combustion engine by circulating cooling water in a water jacket provided in the internal combustion engine body.
Cooling water injection means for injecting cooling water into each of the cylinders on the outer peripheral wall of the cylinder forming the combustion chamber of each cylinder of the internal combustion engine, and the cooling when the explosion / expansion process is performed in each of the cylinders. Internal combustion having injection control means for controlling the injection amount of the cooling water injected from the water injection means to the cylinder outer peripheral wall of each cylinder to be smaller than the injection amount when the explosion / expansion process is not performed in each cylinder Solved by the engine cooling system.

[0016]

In the cooling device for an internal combustion engine according to the present invention, the cooling water injection means injects a large amount of cooling water when the explosion / expansion process is not performed in each cylinder. Therefore, when the intake is performed in each of the cylinders, each of the cylinders is sufficiently cooled, and the dense air is sucked into the cylinder.

Further, when the explosion / expansion process is performed in each of the cylinders, the cooling capacity by the cooling water is lower than when the explosion / expansion process is performed, and the cylinders of the cylinders are generated. The combustion energy generated is mainly converted into mechanical energy, and cooling loss is reduced.

[0018]

1 is a block diagram of an embodiment of a cooling device for an internal combustion engine according to the present invention.

In FIG. 1, reference numeral 1 indicates a cylinder block of an internal combustion engine equipped with the cooling device of this embodiment. Also, reference numeral 2
Is a cylinder liner arranged for each cylinder of the internal combustion engine,
Reference numeral 3 indicates a piston that slides inside each cylinder liner 2. Here, as shown in FIG. 1, the cylinder block 1
A predetermined space is provided between the cylinder liner 2 and the cylinder liner 2. This interval mainly constitutes the cylinder water jacket 4 through which the cooling water for cooling the cylinder liner 2 flows.

A cylinder head 5 is arranged above the cylinder block 1. The cylinder head 5 and the space defined by the inner wall of the cylinder liner 2 and the upper surface of the piston 3 form a combustion chamber 6 in each cylinder of the internal combustion engine.
Further, the cylinder head 5 is provided with an intake port 9 and an exhaust port 10 which communicate with the combustion chamber 6 via an intake valve 7 and an exhaust valve 8, respectively.

In the vicinity of the intake port 9 and the exhaust port 10, there are provided an intake water jacket 11 and an exhaust water jacket 12 which mainly circulate cooling water for cooling them.
In this embodiment, the intake water jacket 11 and the exhaust water jacket 12 are provided independently for each cylinder. In addition, these intake water jacket 11 and exhaust water jacket 12
And communicate with each other in the cylinder head 5.

Therefore, the intake water jacket 1
The cooling water supplied to No. 1 cools the intake port 9 and the exhaust port 10 of the cylinder in which the intake water jacket 11 is arranged, and then flows to the exhaust water jacket 12.

Further, between the intake port 9 and the exhaust port 10 of the cylinder head 5, that is, at a portion corresponding to the upper portion of the combustion chamber 6, a combustion chamber for mainly circulating cooling water for cooling the upper portion of the combustion chamber 6 is provided. A water jacket 13 is provided. The cylinder block 1 and the cylinder head 5
When installed, the combustion chamber water jacket 13
Is in communication with the cylinder water jacket 4 described above. Therefore, the cooling water supplied to the combustion chamber water jacket 13 flows into the cylinder water jacket 4 after cooling the upper portion of the combustion chamber 6.

Further, as shown in FIG. 1, the cylinder water jacket 4 and the combustion chamber water jacket 13 are
A cooling water injection valve 14 corresponding to the above-mentioned cooling water injection means,
15, 16 are provided. These cooling water injection valves 1
4, 15 and 16 are electrically connected to an electronic control unit (ECU) 17 corresponding to the above-mentioned injection control means, and EC
The valve is configured to open or close based on the drive signal supplied from U17.

In FIG. 1, reference numeral 18 indicates a radiator.
The radiator 18 cools the cooling water flowing through it while cooling water flowing from the cooling water inlet 18a flows out from the cooling water outlet 18b to a proper temperature. Radiator 1
The cooling water flowing out from the cooling water outlet 18 b of No. 8 is guided to the inlet 19 a of the cooling water pump 19. Then, the cooling water pump 19 raises the pressure to an appropriate water pressure and the outlet 19b.
Drained from.

The cooling water flowing out from the cooling water pump 19 is
It is guided to the intake water jacket 11 and the cooling water injection valves 14, 15 and 16 through the cooling water passage 20. Here, as described above, the intake water jacket 1
Since 1 communicates with the exhaust water jacket 12, the cooling water guided to the intake water jacket 11 flows through the cylinder head 5 to reach the exhaust water jacket 12, and then the cooling water passage 2
It circulates through 1 to the radiator 18.

On the other hand, the cooling water introduced to the cooling water injection valves 14, 15 and 16 is the cooling water injection valves 14, 15 and
The fuel is injected into the cylinder water jacket 4 and the combustion chamber water jacket 13 only while the valve 16 is open, and the cooling water injection valves 14, 15, 16 are in a state in which the flow is blocked during the other periods. The cooling water injected into the cylinder water jacket 4 and the combustion chamber water jacket 13 passes through the cooling water passage 22 that connects the cylinder water jacket 4 and the radiator 18 to each other.
Cycle to 8.

By the way, when the internal combustion engine is cooled by circulating cooling water, if the cooling is insufficient, the sucked air thermally expands and the air density in the combustion chamber 6 decreases. When the air density decreases in this way, not only the combustion energy of the fuel cannot be sufficiently secured, but also a large amount of unburned components (HC, CO) are contained in the exhaust gas due to lack of air.

On the other hand, if excessive cooling is performed, the heat generated by the combustion of the fuel is absorbed by the cooling medium, and the combustion pressure commensurate with the fuel burned in the combustion chamber 6 cannot be obtained. That is, the combustion energy of the fuel is mainly converted into cooling loss and mechanical energy that is the running energy of the vehicle. If the cooling loss is large, the mechanical energy naturally decreases.

By the way, the cooling loss in the internal combustion engine is a problem in the explosion / expansion process in which combustion energy is generated in the internal combustion engine, and the air density is influenced by the internal combustion engine in the intake process. Is the temperature. That is, unless the cooling is excessive during the explosion / expansion process in each cylinder, the combustion pressure does not decrease and the mechanical energy taken out does not decrease.
Regarding the air density in the combustion chamber, the temperature of the internal combustion engine during the explosion / expansion process does not matter as long as the temperature of the internal combustion engine during the intake process is low.

Therefore, in this embodiment, as described above, the cooling water circulation path of the internal combustion engine is divided into two routes, namely, the intake water jacket 11 and the exhaust water jacket 12 which mainly cool the intake port 9 and the exhaust port 10. And a second route mainly consisting of the cylinder water jacket 4 for cooling the combustion chamber 6 and the combustion chamber water jacket 13.

That is, the cooling water is constantly circulated in the intake water jacket 11 and the exhaust water jacket 12, which are provided mainly for the purpose of cooling the intake port 9 and the exhaust port 10, and the intake port 9 and the exhaust port are constantly kept at a high capacity. Cool 10. Then, in the cylinder water jacket 4 and the combustion chamber water jacket 13 which are mainly provided for the purpose of cooling the combustion chamber 6, the cooling water is circulated only when the explosion / expansion process is not performed in each cylinder. There is.

That is, the ECU 17 which supplies a drive signal to the cooling water injection valves 14, 15 and 16 arranged in each cylinder detects the crank angle in each cylinder based on the signal supplied from the crank angle sensor 23. Then, the valve opening signal is output only to the cylinder in which the explosion / expansion process is not performed.

Therefore, when each process of exhaust, intake and compression is performed in each cylinder, the combustion chamber 6 is cooled with high efficiency by the injected cooling water, and in combination with the effect of the intake water jacket 11, the intake is performed. The air density of the generated air is maintained at a high level. Further, since the cooling water is not injected when the explosion / expansion process is performed in each cylinder, the cooling loss is small and the combustion energy can be converted into mechanical energy with high efficiency.

In the cylinder water jacket 4 and the combustion chamber water jacket 13, the cylinder liner 2 and the like are cooled by the heat of vaporization when the injected cooling water is vaporized. Therefore, it is not necessary to circulate a large amount of cooling water, and the entire cooling device can be downsized.

Further, as shown in FIG. 1, the cylinder liner 2
A large number of convex portions 2a are formed on the outer periphery of the. The convex portion 2a is provided to secure a large surface area of the cylinder liner 2 without deteriorating the water drop property on the surface. For this reason, the cooling water injected toward the cylinder liner 2 quickly spreads over the entire surface of the cylinder liner 2 to start cooling with a high capacity, and when the injection is stopped, the cooling capacity is lost immediately.

FIG. 2 shows a P-V diagram for explaining the effect of this embodiment, in which the cylinder internal pressure P and the cylinder volume V are shown.
Represents the relationship with. The curve shown by the solid line in FIG. 2 shows the characteristics of the device of this embodiment, and the curve shown by the alternate long and short dash line shows the characteristics of the circulating water type cooling device that has been most commonly used as a cooling device for an internal combustion engine. Shows.

As described above, according to the cooling apparatus of this embodiment, the combustion chamber 6 is cooled with high efficiency by utilizing the heat of vaporization of the cooling water, and the intake port 9 and the exhaust port 10 are independently cooled. It Therefore, the temperature of the intake air can be kept low, and the dense air can be intake in the intake process.

When the crank angle reaches the bottom dead center (BDC) and then the cylinder volume V starts to decrease and the compression process is started, the cylinder pressure V increases as the cylinder volume V decreases. In this case, since the device of this embodiment has a higher cooling capacity than the conventional device, the cylinder internal pressure P can be kept lower than that of the conventional device as shown in FIG. Therefore, the internal combustion engine provided with the cooling device of the present embodiment is less likely to cause knocking as compared with the internal combustion engine provided with the conventional device, and the adjustable range of the ignition timing is expanded, so that higher output can be obtained. Is possible.

Next, when the fuel is ignited by a spark plug (not shown) arranged in the combustion chamber 6, an explosion or
The expansion process is started. Explosion and
At the same time when the expansion process is started, the cooling water injection valves 14, 1
The valves 5 and 16 are closed, and the combustion chamber 6 is no longer cooled.

Therefore, as shown in FIG. 2, in the explosive expansion process, the in-cylinder pressure P is maintained at a high pressure, that is, the combustion pressure in the combustion chamber 6 is maintained at a high pressure as compared with an internal combustion engine equipped with a conventional device. As a result, according to the present embodiment, FIG.
The output of the internal combustion engine is improved by the amount of energy corresponding to the shaded area.

By the way, NO _X contained in the exhaust gas
It has been conventionally known that the higher the temperature in the combustion chamber 6, the more it is generated, and it is effective to lower the temperature in the combustion chamber 6 in order to reduce the discharge amount. On the other hand, depending on the injection stop timing of the cooling water injection valves 14, 15 and 16, the maximum combustion pressure in the explosion / expansion process decreases as shown in FIG. It is possible to lower the temperature of.

Therefore, in this embodiment, the maximum combustion pressure is intentionally lowered by prioritizing the reduction of NO _{x in} the exhaust gas and appropriately setting the injection stop timing of the cooling water at the start of the explosion / expansion process. ing.

As described above, according to the present embodiment, it is possible to miniaturize the cooling device so that the vehicle can be weighed, and in addition, it is possible to secure good air density and reduce cooling loss for each cylinder, and to reduce fuel consumption. Of the exhaust gas and improvement of the output can be realized at the same time, and good exhaust emission can be secured.

A water temperature sensor 24 is connected to the ECU 17 as shown in FIG. That is, in the present embodiment, the ECU 17 performs not only the calculation based on the output signal of the crank angle sensor 23 but also the calculation based on the cooling water temperature, so that the ECU 17 is sufficiently warmed up while the cooling water temperature is low. In comparison, the valve opening time of the cooling water injection valves 14, 15, 16 is controlled to be short.

Therefore, in the present embodiment, the circulation flow rate can be reduced at the cold start and increased at the completion of warm-up without providing an adjusting mechanism such as a thermostat in the cooling water circulation system. Therefore, according to this embodiment, the time required for warming up the internal combustion engine is shortened.

FIG. 3 is a perspective view showing the structure of an example of a cylinder liner suitable for this embodiment. FIG. 3 (A) shows the cylinder liner 2 shown in FIG. C) shows another example of the cylinder liner.

That is, the cylinder liner suitable for the present embodiment is sufficient if it has a large outer surface area and excellent water drainage property, and has a structure of the cylinder liner 2 having a large number of convex portions 2a on the outer circumference. Is not limited. For example, FIG. 3 (B)
As shown in, the spiral groove 25 is formed on the outer circumference of the cylinder liner 25.
It may be provided with a, or as shown in FIG. 3C, a cylinder liner 26 in which a vertical groove 26a is formed on the outer periphery thereof.

[0049]

As described above, according to the present invention, the intake air is improved by injecting the cooling water into each cylinder of the internal combustion engine independently to reduce the cooling capacity during the explosion / expansion process. It is possible to reduce the cooling loss as compared with the conventional cooling device while maintaining a high air density. Therefore, the cooling device for an internal combustion engine according to the present invention has a feature of significantly improving the fuel consumption and the output of the internal combustion engine as compared with the conventional device.

[Brief description of drawings]

FIG. 1 is an overall view showing a configuration of an internal combustion engine cooling device according to the present invention.

FIG. 2 is a diagram for explaining the effect of the cooling device for an internal combustion engine according to the present invention.

FIG. 3 is a perspective view showing an example of a cylinder liner suitable for the apparatus of this embodiment.

[Explanation of symbols]

 1 Cylinder Block 2 Cylinder Liner 3 Piston 4 Cylinder Water Jacket 5 Cylinder Head 6 Combustion Chamber 11 Intake Water Jacket 12 Exhaust Cylinder Jacket 13 Combustion Chamber Cylinder Jacket 14, 15, 16 Cooling Water Injection Valve 17 Electronic Control Unit 23 Crank Angle Sensor

Claims (1)

[Claims] 1. A cooling device for an internal combustion engine, in which cooling water is circulated in a water jacket provided in an internal combustion engine body to cool the internal combustion engine, wherein an outer peripheral wall of a cylinder forming a combustion chamber of each cylinder of the internal combustion engine comprises: Cooling water injecting means for injecting cooling water into each of the cylinders, and cooling water injected from the cooling water injecting means to the cylinder outer peripheral wall of each of the cylinders when an explosion / expansion process is performed in each of the cylinders And an injection control unit that controls the injection amount of the injection amount to a smaller amount than the injection amount when the explosion / expansion process is not performed in each of the cylinders.