JP2012189063A - Cooling apparatus for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling apparatus for an internal combustion engine that includes a supercharger and an EGR and can suppress the occurrence of knocking.SOLUTION: The internal combustion engine 10 includes a turbocharger 60, the EGR device, a low water temperature cooling EGR cooler 32 and a high temperature cooling EGR cooler 40. The internal combustion engine includes an import cooling water passage 30, and supplies a cooling medium to the import cooling water passage 30. A switch valve 24 is provided in a connection of a cooling water passage 22 to the import cooling water passage 30. An ECU 70 controls the switch valve 24 so that the cooling medium is started to circulate in the import cooling water passage 30 when the internal combustion engine 10 is operated by the EGR device in a predetermined high load range, which is an outside region of an EGR region.

Description

  The present invention relates to a cooling device for an internal combustion engine.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-176741, an internal combustion engine that performs cooling of an exhaust gas recirculation device in an intermediate load state or a high load state is known. The internal combustion engine according to this prior art includes a supercharger and a device for performing exhaust gas recirculation (hereinafter also referred to as “EGR”) (hereinafter also referred to as “EGR device”). In the internal combustion engine according to the present invention, from the viewpoint of reducing the generation of NOx and the generation of particulate matter, the intake air sucked into the cylinder of the engine body is performed by cooling the exhaust gas recirculation device in the above specific load state. It enjoys the effect of suppressing the increase in combustion temperature due to the decrease in temperature.

JP 2003-176741 A JP 2010-151066 A

  According to the external EGR mechanism that recirculates the exhaust gas cooled by the low water temperature cooling water, the intake air temperature can be lowered by recirculating the exhaust gas cooled to a low temperature to the intake passage. As a result, knocking can be suppressed. Even in an internal combustion engine having a supercharger, the intake pressure is lower than the back pressure in a region where supercharging is not performed or in a region where the supercharging pressure is low, and a desired amount of EGR can be introduced into the intake passage. The knocking suppression effect by introducing such cooled EGR can be enjoyed. However, on the other hand, when the supercharging is performed, the region where the intake pressure increases (that is, the back pressure and the back pressure) are increased such that the introduction amount of the EGR gas falls below a desired amount or the EGR gas cannot be introduced. There is a region where the differential pressure of the intake pressure becomes small. When the introduction of EGR such as the amount of introduction of EGR gas is reduced or the introduction of EGR gas is prevented in this way, the knocking suppression effect secured by the introduction of cooled EGR is reduced. Resulting in.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a cooling device for an internal combustion engine capable of suppressing knocking in an internal combustion engine including a supercharger and an EGR device. To do.

In order to achieve the above object, a first invention is a cooling device for cooling an internal combustion engine including a supercharger and an EGR device,
A first refrigerant passage provided in the EGR device so as to cool the EGR gas recirculated by the EGR device;
A second refrigerant passage provided in the internal combustion engine so as to cool an intake port of the internal combustion engine;
Refrigerant supply means for supplying refrigerant to the first refrigerant passage and the second refrigerant passage;
When the internal combustion engine is operated in a predetermined high load region that is outside the EGR region by the EGR device, or starts the circulation of the refrigerant in the second refrigerant passage, or the second refrigerant passage Control means for controlling the supply of the refrigerant to the second refrigerant passage so as to increase the flow rate of the refrigerant inside,
It is characterized by providing.

The second invention is the first invention, wherein
The EGR device
A first EGR cooler that communicates with an engine coolant passage through which the engine coolant of the internal combustion engine flows, and that cools EGR gas with a refrigerant having a first temperature that flows in the engine coolant passage;
A second EGR cooler connected to the first refrigerant passage and flowing in the first refrigerant passage to cool EGR gas with a refrigerant having a second temperature lower than the first temperature;
Including
The second refrigerant passage includes a connection portion connected to the first refrigerant passage,
A valve that is provided in the connecting portion and capable of changing a flow of the refrigerant with respect to the first refrigerant passage and the second refrigerant passage;
The control means includes valve control means for controlling supply of the refrigerant to the second refrigerant passage by switching an open / close state of the valve.

The third invention is the second invention, wherein
The second refrigerant passage is connected to the first refrigerant passage so as to bypass the second EGR cooler starting from the valve.

According to a fourth invention, in any one of the first to third inventions,
The predetermined high load region is a load region where knocking of the internal combustion engine occurs.

  According to the first invention, the intake port can be cooled when the internal combustion engine is operated outside the EGR region and in a predetermined high load region. Thereby, the intake port can be cooled and the intake air temperature can be lowered so as to cope with the situation where the introduction of the cooled EGR is hindered. As a result, knocking suppression can be ensured.

  According to the second invention, in the EGR cooler provided with a mechanism for performing two-stage cooling, the cooling water can be shared by the cooling of the intake port.

  According to the third invention, a part or all of the refrigerant flows from the first refrigerant passage that supplies the refrigerant to the second EGR cooler to the second refrigerant passage by bypassing the second EGR cooler. Cooling can be performed.

  According to the fourth invention, the intake port can be reliably cooled when necessary from the viewpoint of knocking suppression, and the intake port can be kept from cooling when it is not necessary.

It is a figure which shows the structure of the cooling device of the internal combustion engine concerning Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the cooling device of the internal combustion engine concerning Embodiment 1 of this invention. It is a flowchart of the routine which ECU performs in the cooling device of the internal combustion engine concerning Embodiment 1 of this invention. It is a figure which shows the structure of the cooling device of the internal combustion engine concerning Embodiment 2 of this invention. It is a figure for demonstrating operation | movement of the cooling device of the internal combustion engine concerning Embodiment 2 of this invention. It is a flowchart of the routine which ECU performs in the cooling device of the internal combustion engine concerning Embodiment 2 of this invention.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram illustrating a configuration of a cooling device for an internal combustion engine according to a first embodiment of the present invention. FIG. 1 also shows a part of the system configuration of the internal combustion engine 10 together with the cooling apparatus according to the first embodiment. The internal combustion engine 10 is suitable for a moving body such as a vehicle. The internal combustion engine 10 according to the present embodiment is an in-line four-cylinder engine having four cylinders (# 1 cylinder to # 4 cylinder aligned in a row) as an example. As will be described below, the internal combustion engine 10 is a supercharged internal combustion engine having a turbocharger 60 and an EGR (Exhaust Gas Recirculation) device that can introduce cooled EGR gas into an intake passage.

Although not shown, the internal combustion engine 10 includes an intake passage for taking air into the cylinder and an exhaust passage through which exhaust gas discharged from the cylinder flows.
An air flow meter (not shown) that outputs a signal corresponding to the flow rate of air sucked into the intake passage is provided near the inlet of the intake passage of the internal combustion engine 10. A compressor of the turbocharger 60 is disposed downstream of the air flow meter. The turbocharger 60 includes a turbine that is integrally connected to the compressor and that is operated by exhaust gas exhaust energy. Further, the compressor is driven to rotate by exhaust energy of exhaust gas input to the turbine.
A water-cooled intercooler 20 is disposed in the intake passage on the downstream side of the compressor. The water-cooled intercooler 20 is a water-cooled intercooler for cooling the air compressed by the compressor. Further, an electronically controlled throttle valve (not shown) for adjusting the amount of air flowing through the intake passage is disposed downstream of the water-cooled intercooler 20.

  One end of an EGR passage (not shown) is connected to the exhaust passage of the internal combustion engine 10. The other end of the EGR passage is connected to an intake passage (a surge tank) on the downstream side of the throttle valve. A low water temperature cooling EGR cooler 32 and a high water temperature cooling EGR cooler 40 are provided in the middle of the EGR passage. An EGR valve (not shown) for opening and closing the EGR passage is provided in the EGR passage on the downstream side of these EGR coolers. The EGR valve has a stepping motor (not shown) as a drive source. According to such a configuration, it is possible to perform so-called external EGR (Exhaust Gas Recirculation) control through which the exhaust gas flowing through the exhaust passage is recirculated to the intake passage via the EGR passage.

The cooling device for an internal combustion engine according to the first embodiment is formed with low-temperature cooling water passages (cooling water passage 22, cooling water passage 25, cooling water passage 26, cooling water passage 28). The cooling water after cooling the water-cooled intercooler 20 (low-temperature cooling water) flows through this low-temperature cooling water channel. The flow direction of the cooling water in the system through which the low-temperature cooling water flows is as shown by the arrows in FIG. 1 along each cooling water passage.
The system through which the low-temperature cooling water according to the first embodiment flows is provided in a system separate from the engine cooling water. This low-temperature cooling water is set to be supplied to the turbocharger 60 at a lower temperature than the engine cooling water. The low-temperature cooling water is configured to circulate between the low-temperature cooling water channel, the water-cooling intercooler 20, and the sub-radiator 34 for cooling the low-temperature cooling water by a low-temperature cooling water pump (not shown). Yes.

The internal combustion engine cooling apparatus according to the first embodiment includes a switching valve 24. The switching valve 24 is disposed in the cooling water passage 22 downstream of the water cooling intercooler 20 and upstream of the low water temperature cooling EGR cooler 32. The switching valve 24 is connected to the imported cooling water passage 30. The imported cooling water passage 30 is a cooling water passage formed near the intake port of the cylinder head so as to cool the intake port (import) of the internal combustion engine 10.
The switching valve 24 can switch the direction of the flow of the cooling water from the cooling water passage 22 between a direction of flowing to the low water temperature cooling EGR cooler 32 side and a direction of flowing to the import cooling water passage 30 side. . As the switching valve 24, a valve that can selectively switch the flow direction between the low water temperature cooling EGR cooler 32 side and the imported cooling water passage 30 is used. A valve that can distribute the cooling water at a desired ratio between the low water temperature cooling EGR cooler 32 side and the imported cooling water passage 30 (here, a valve mechanism including a combination of a plurality of valves is simply referred to as a “valve”). Can be used).

The internal combustion engine cooling apparatus according to the first embodiment includes a high-temperature cooling water passage (a cooling water passage 42, a cooling water passage 44, and a cooling water passage 48), as schematically shown in FIG. Normal engine cooling water (high temperature cooling water) flows through this high temperature cooling water channel. The flow direction of the cooling water in the system through which this high-temperature cooling water flows is as shown by the arrows shown along each cooling water passage in FIG.
The high temperature cooling water circulates between a cooling water channel for a predetermined cooling part of the internal combustion engine including the high temperature cooling water channel and a main radiator 52 for cooling the high temperature cooling water. This circulation is performed by driving a pump 46 for high-temperature cooling water. A thermostat 50 is provided between the main radiator 52 and the pump 46 in the cooling water passage 44. The cooling water passage 48 connects a portion of the cooling water passage 44 between the pump 46 and the thermostat 50 and the cooling water passage 42.

  As described above, the EGR device according to the first embodiment includes the “two-stage cooling mechanism of the EGR cooler”. That is, the EGR cooler according to the first embodiment forms a two-stage cooling mechanism by the “high water temperature cooling EGR cooler 40 using engine cooling water” and the “low water temperature cooling EGR cooler 32 using cooling water of the water cooling intercooler 20”. ing. According to the configuration of the first embodiment, due to the presence of the switching valve 24, the cooling water of the low water temperature cooling EGR cooler 32 of the two stages of EGR coolers is transferred to the imported cooling water passage 30 as necessary. It can flow.

The system shown in FIG. 1 includes an ECU (Electronic Control Unit) 70. In addition to the air flow meter described above, the ECU 70 includes an internal combustion engine 10 such as a crank angle sensor for detecting the engine speed and an exhaust temperature sensor for detecting the temperature of exhaust gas flowing through the exhaust passage. Various sensors for detecting the operating state are connected.
Further, in addition to the throttle valve, EGR valve, and pump described above, the output portion of the ECU 70 includes an internal combustion engine such as a fuel injection valve for supplying fuel to the internal combustion engine, and an ignition plug for igniting the air-fuel mixture. Various actuators are connected to control the operation state. The ECU 70 controls the operating state of the internal combustion engine by operating various actuators according to a predetermined program based on the outputs of the various sensors described above.
The ECU 70 can calculate the engine speed and load of the internal combustion engine 10 based on the output signals from the various sensors. The output unit of the ECU 70 is connected to the switching valve 24. The switching valve 24 can switch the communication state of the cooling water passage as described above in accordance with a control signal from the ECU 70.

[Operation of Embodiment 1]
FIG. 2 is a diagram for explaining the operation of the internal combustion engine cooling apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship between the EGR region and the knock region in the internal combustion engine 10 according to the first embodiment. FIG. 2 shows a WOT (Wide Open Throttle) line, a knock line, and an EGR region (hatched) on the plane showing the characteristics of the engine load and the engine speed for the internal combustion engine 10 according to the first embodiment. Area).

  In the cooling apparatus for an internal combustion engine according to the first embodiment, when the internal combustion engine 10 is operated in the EGR region as indicated by a point A in FIG. 2, the ECU 70 sets the switching valve 24 to “the cooling water passage 22. To control the cooling water to flow through the low water temperature cooling EGR cooler 32 and the cooling water passage 25 ”. Thereby, the cooling capacity of both the high water temperature cooling EGR cooler 40 and the low water temperature cooling EGR cooler 32 can be utilized for cooling the EGR. The cooled EGR is returned to the intake passage, whereby the intake air temperature can be lowered.

  On the other hand, in the cooling apparatus for an internal combustion engine according to the first embodiment, the internal combustion engine 10 is operated in an “outside of the EGR region and a region where the load is high enough to cause knocking” as indicated by a point B in FIG. In this case, the ECU 70 controls the switching valve 24 so that the cooling water flows from the cooling water passage 22 via the imported cooling water passage 30 and the cooling water passage 25. Thereby, the cooling water which has flowed to the low water temperature cooling EGR cooler 32 at the point A can be flowed to the imported cooling water passage 30 to cool the intake port. The intake air temperature can be lowered by cooling the intake port.

In the case of an external EGR mechanism that uses low-temperature cooling water, the EGR gas can be cooled to a low temperature, and the intake air temperature can be lowered by introducing the cooled EGR gas into the intake passage in the EGR region. . Thereby, knocking suppression effect can be acquired. However, when the load is high, the differential pressure (difference between the back pressure and the intake pressure) becomes small, which makes it difficult to introduce the external EGR. More specifically, the supercharging causes the intake pressure to be higher than that of an NA (natural intake) engine, so that the differential pressure becomes smaller and the area where external EGR cannot be introduced becomes larger. In addition, in the case of a supercharged engine, there is a circumstance that the knocking region is large. As a result of the difficulty in introducing EGR, the knocking suppression effect secured by the introduction of cooled EGR may be reduced, and it is preferable to deal with this.
Therefore, the internal combustion engine cooling apparatus according to the first embodiment is a region that is so heavily loaded that knocking occurs in a region outside the EGR region (such as point B in FIG. 2). ), The switching valve 24 can be controlled “so that cooling water flows from the cooling water passage 22 via the imported cooling water passage 30 and the cooling water passage 25”. Thereby, the intake port can be cooled and the intake air temperature can be lowered so as to cope with the situation where the introduction of the cooled EGR is hindered. As a result, knocking suppression can be ensured.
Further, according to the cooling apparatus for an internal combustion engine according to the first embodiment, in the EGR cooler (low water temperature cooling EGR cooler 32 and high water temperature cooling EGR cooler 40) provided with a mechanism for performing two-stage cooling, the switching valve 24 With the switching control, the intake air temperature can be lowered by sharing a part of the cooling water for cooling the intake port.

[Specific Processing in First Embodiment]
Hereinafter, a specific process executed by the cooling apparatus for an internal combustion engine according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a flowchart of a routine executed by the ECU 70 in the internal combustion engine cooling apparatus according to the first embodiment of the present invention. The ECU 70 repeatedly executes this routine at a predetermined cycle while the internal combustion engine 10 is in operation.

In the routine shown in FIG. 3, first, the ECU 70 executes a process for determining whether or not the internal combustion engine 10 is operated in the EGR region (step S100). In this step, the ECU 70 first specifies the current operating region (load, engine speed) of the internal combustion engine 10 based on the output signals of various sensors attached to the internal combustion engine 10. Next, the ECU 70 executes a process for determining whether or not the specified operation region belongs to a predetermined EGR region stored in advance by a map or the like.
If it is determined that the current operation region is within the EGR region, the condition of step S100 is satisfied (Yes), and the current routine is terminated. This is because the operation can be performed in the EGR region, so that the cooled EGR can be introduced, and the introduction of the cooled EGR can suppress the knocking.

If the condition of step S100 is not satisfied (No), the ECU 70 next executes a process of determining whether or not the internal combustion engine 10 is operated in the knock region (step S102). In this step, the ECU 70 determines that the current operation region of the internal combustion engine 10 specified in step S100 is a predetermined knock region (in the case of the first embodiment, a region with a higher load than the knock line in FIG. 2). A process for determining whether or not there is present is executed. The knock region may be stored in the ECU 70 in advance as a map or the like.
If it is determined that the current operation region is not within the knock region, the condition of step S102 is not satisfied (No), and the current routine is terminated.

When the condition of step S102 is satisfied (Yes), the ECU 70 sets a path on the low water temperature cooling EGR cooler 32 side in the switching valve 24 so that the flow of the cooling water to the low water temperature cooling EGR cooler 32 is blocked. A control process for closing is executed (step S104).
Next, the ECU 70 executes control processing for opening the path to the imported cooling water passage 30 in the switching valve 24 so that the flow of the cooling water to the imported cooling water passage 30 is started (step S106).

  According to the series of processes in steps S100 to S106, the internal combustion engine 10 including the supercharger (turbocharger 60) and the EGR device performs knocking suppression as described in the operation section according to the first embodiment. be able to. That is, when the process proceeds to step S104 according to the determination results of steps S100 and S102, the internal combustion engine 10 is operated in “outside the EGR region and knock region”. According to the cooling apparatus for an internal combustion engine according to the first embodiment, in this case, the ECU 70 performs “the path of the cooling water passage 22 → the imported cooling water passage 30 → the cooling water passage 25” by the processing of steps S104 and S106. The switching valve 24 can be controlled so that the cooling water flows. Thereafter, the current routine ends.

  According to the process according to the first embodiment described above, the intake port can be cooled and the intake air temperature can be lowered so as to cope with the situation where the introduction of the cooled EGR is hindered. As a result, knocking suppression can be ensured. Further, according to the processing according to the first embodiment described above, after accurately determining whether or not the internal combustion engine 10 is operating in the “out of EGR region” and in the “higher load region than the knock line”, The switching valve 24 can be controlled. For this reason, it is possible to reliably take a cooling measure for the intake port when necessary from the viewpoint of suppressing knocking, and to refrain from cooling the intake port when it is not necessary.

  In the first embodiment described above, the turbocharger 60 is connected to the “supercharger” in the first invention, and the external EGR device (not shown) attached to the internal combustion engine 10 is the “supercharger” in the first invention. It corresponds to “EGR device”. In the first embodiment described above, the cooling water passages 22, 25, 26, 28 are the “first refrigerant passage” in the first invention, and the imported cooling water passage 30 is the first invention. These correspond to “second refrigerant passages”, respectively. In the first embodiment described above, the water-cooled intercooler 20, the sub-radiator 34, and the low-temperature cooling water pump (not shown) correspond to the “refrigerant supply means” in the first invention. Further, in the first embodiment described above, the ECU 70 executes the processing of steps S100 to S106 of the routine of FIG. It has been realized.

  In the first embodiment described above, the high water temperature cooling EGR cooler 40 is the “first EGR cooler” in the second invention, and the cooling water passages 42, 44 and 48 are the “engine” in the second invention. In the “cooling water passage”, the low water temperature cooling EGR cooler 32 corresponds to the “second EGR cooler” in the second invention, and the switching valve 24 corresponds to the “valve” in the second invention.

In the first embodiment, the imported cooling water passage 30 is connected to the cooling water passages 22 and 25 so as to bypass the low water temperature cooling EGR cooler 32. In other words, the intake cooling water passage 30 can be branched from the middle of the cooling water passage system for the low water temperature cooling EGR cooler 32 to cool the intake port using the cooling water used for cooling the low water temperature cooling EGR cooler 32. The configuration is as follows. However, the present invention is not limited to this. The imported cooling water passage 30 may be a cooling system separate from the cooling system applied to the low water temperature cooling EGR cooler 32.
In addition, as one of the modified examples, when a valve capable of adjusting the flow distribution is used for the switching valve 24 instead of the alternative switching valve, the imported cooling water has already been reached when the processing of steps S104 and S106 is reached. It is conceivable that there is a flow of cooling water in the passage 30 (when cooling water is distributed). In the case of such a modification, the ECU 70 opens the valve opening on the side of the imported cooling water passage 30 so as to increase the flow rate of the cooling water in the import cooling water passage 30 (enhance the flow) in step S106. You may perform control which enlarges.
The cooling apparatus for an internal combustion engine according to the first embodiment includes a low water temperature cooling EGR cooler 32 and a high water temperature cooling EGR cooler 40, that is, includes a “two-stage cooling mechanism of an EGR cooler”. However, the present invention is not limited to this. The present invention may be applied to a cooling device for an internal combustion engine having only one EGR cooler. Specifically, an imported cooling water passage 30 and a switching valve with respect to the cooling water passage for the one EGR cooler. 24 may be provided to execute the specific control according to the first embodiment.

Embodiment 2. FIG.
FIG. 4 is a diagram illustrating the configuration of the cooling device for an internal combustion engine according to the second embodiment of the present invention. The internal combustion engine cooling apparatus according to the second embodiment has the same hardware configuration as that of the first embodiment shown in FIG. 1 except that the switching valve 140 and the export coolant passage 142 are provided. In order to avoid redundant description, the description of the hardware configuration will be omitted or simplified as appropriate.

The internal combustion engine cooling apparatus according to the first embodiment includes an export cooling water passage 142. The exhaust cooling water passage 142 is a cooling water passage formed in the vicinity of the exhaust port of the cylinder head so as to cool the exhaust port (export) of the internal combustion engine 10. One end of the export cooling water passage 142 is connected to the imported cooling water passage 30. The other end of the exhaust cooling water passage 142 is connected to a downstream portion of the low water temperature cooling EGR cooler 32 in the cooling water passage 25. The connecting portion where the other end of the outlet cooling water passage 142 is connected to the cooling water passage 25 is closer to the low water temperature cooling EGR cooler 32 than the portion where the imported cooling water passage 30 is connected to the cooling water passage 25.
A switching valve 140 is provided at a connection portion where the exhaust cooling water passage 142 and the imported cooling water passage 30 are connected. The switching valve 140 is a switching valve that can switch the flow direction of the cooling water, similarly to the switching valve 24 according to the first embodiment. The switching valve 140 is connected to the ECU 70, and the switching valve 140 can flow the cooling water flowing through the imported cooling water passage 30 to the export cooling water passage 142 in accordance with a control signal from the ECU 70. As a result, the low-temperature cooling water can flow through the exhaust cooling water passage 142, and the exhaust port can be cooled.

  FIG. 5 is a diagram for explaining the operation of the cooling device for an internal combustion engine according to the second embodiment of the present invention. FIG. 5 is a diagram illustrating a relationship between the EGR region and the λ = 1 region in the internal combustion engine 10 according to the first embodiment. FIG. 5 shows the WOT line and the EGR region as in FIG. 1, and also shows the λ = 1 line.

  In the cooling system for an internal combustion engine according to the second embodiment, when the internal combustion engine 10 is operated in the EGR region as indicated by a point A in FIG. 5, the ECU 70 sets the switching valve 24 to “the cooling water passage 22. Control so that the cooling water flows through the low water temperature cooling EGR cooler 32 and the cooling water passage 25, and the switching valve 140 is disconnected from the connection between the imported cooling water passage 30 and the export cooling water passage 142. To control. Thereby, also in Embodiment 2, as in Embodiment 1, the cooling capacities of both the high water temperature cooling EGR cooler 40 and the low water temperature cooling EGR cooler 32 can be used for cooling the EGR. The cooled EGR is returned to the intake passage, whereby the intake air temperature can be lowered.

  On the other hand, in the cooling apparatus for an internal combustion engine according to the second embodiment, when the internal combustion engine 10 is operated “outside the EGR region and near the boundary of λ = 1” as indicated by a point C in FIG. However, the switching valve 24 is controlled so that the cooling water flows from the cooling water passage 22 to the imported cooling water passage 30 and the switching valve 140 is controlled via the import cooling water passage 30 via the export cooling water passage 142. Control the cooling water so that it flows. As a result, the cooling water flowing to the low water temperature cooling EGR cooler 32 at the point A can be flowed to the import cooling water passage 30 to cool the intake port, and the cooling water is further supplied to the exhaust cooling water passage 142. And the exhaust port can be cooled. By performing such control, the internal combustion engine cooling apparatus according to the second embodiment can reduce the intake air temperature by cooling the intake port, and is not in the EGR region and in the vicinity of the λ = 1 boundary. The λ = 1 region can also be enlarged by cooling the exhaust port.

  Hereinafter, a specific process executed by the cooling apparatus for an internal combustion engine according to the second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart of a routine executed by the ECU 70 in the internal combustion engine cooling apparatus according to the second embodiment of the present invention. The ECU 70 repeatedly executes this routine at a predetermined cycle while the internal combustion engine 10 is in operation.

  In the routine shown in FIG. 6, first, the processes of steps S100, S102, S104, and S106 are executed in the same manner as the routine according to the first embodiment shown in FIG. Thus, when the internal combustion engine 10 is operated in “outside the EGR region and in the knock region”, the cooling water flows through the path of the cooling water passage 22 → the imported cooling water passage 30 → the cooling water passage 25. In addition, the switching valve 24 can be controlled.

  After the processing of step S106 is executed, next, in the specific processing according to the second embodiment, the ECU 70 executes processing for determining whether or not the internal combustion engine 10 is operating in the λ <1 region (step 1). S200). For example, a point C plotted in a higher load and higher rotation speed range than the λ = 1 line in FIG. 5 is a point where the determination result in step S200 is affirmative (Yes). If the determination result in step S200 is affirmative (Yes), it can be determined that “the operation is higher in the EGR region and in the λ <1 region”. When the condition of this step is not established (No), this routine is terminated because it does not correspond to the operation in such an operation region.

  When the satisfaction of the condition of step S200 (Yes) is confirmed (that is, when the determination result that “the internal combustion engine 10 is operating in the λ <1 region” is obtained), the ECU 70 reads the imported cooling water. A control process for opening the switching valve 140 is performed so as to establish a connection between the passage 30 and the outlet coolant passage 142 (that is, establishment of communication between them) (step S202). Thereby, the cooling water can be allowed to flow into the export cooling water passage 142 together with the imported cooling water passage 30. As a result of such a series of processes, the λ = 1 region can be expanded by cooling the exhaust port not in the EGR region and in the vicinity of the λ = 1 boundary. Thereafter, the current routine ends.

In the second embodiment, the exhaust cooling water passage 142 is provided as an independent system separate from the cooling system of the EGR cooler (the high water temperature cooling EGR cooler 40 and the low water temperature cooling EGR cooler 32), or the export cooling water passage 142 is provided. It may be provided as an independent system separate from the imported cooling water passage 30. Further, the configuration for intake port cooling (import cooling water passage 30, switching valve 24, and other configurations) and control according to the first embodiment, and the exhaust port cooling configuration (export cooling water passage 142, switching) according to the second embodiment. Valve 140 and other configurations) and control may be performed separately (embodiment 2 alone).
Further, as in the modification described in the first embodiment for the switching valve 24, the switching valve 140 is not limited to the alternative switching valve, and a part of the cooling water in the imported cooling water passage 30 may be used at a desired ratio. A valve (valve mechanism) capable of changing the flow rate distribution that can be introduced into the exhaust coolant passage 142 may be used.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 20 Water cooling intercooler 22 Cooling water passage 24 Switching valve 25 Cooling water passage 26 Cooling water passage 28 Cooling water passage 30 Imported cooling water passage 32 Low water temperature cooling EGR cooler 34 Sub radiator 40 High water temperature cooling EGR cooler 42 Cooling water passage 44 Cooling water passage 46 Pump 48 Cooling water passage 50 Thermostat 52 Main radiator 60 Turbocharger 140 Switching valve 142 Exhaust cooling water passage

Claims (4)

A cooling device for cooling an internal combustion engine including a supercharger and an EGR device,
A first refrigerant passage provided in the EGR device so as to cool the EGR gas recirculated by the EGR device;
A second refrigerant passage provided in the internal combustion engine so as to cool an intake port of the internal combustion engine;
Refrigerant supply means for supplying refrigerant to the first refrigerant passage and the second refrigerant passage;
When the internal combustion engine is operated in a predetermined high load region that is outside the EGR region by the EGR device, or starts the circulation of the refrigerant in the second refrigerant passage, or the second refrigerant passage Control means for controlling the supply of the refrigerant to the second refrigerant passage so as to increase the flow rate of the refrigerant inside,
A cooling device for an internal combustion engine, comprising: The EGR device
A first EGR cooler that communicates with an engine coolant passage through which the engine coolant of the internal combustion engine flows, and that cools EGR gas with a refrigerant having a first temperature that flows in the engine coolant passage;
A second EGR cooler connected to the first refrigerant passage and flowing in the first refrigerant passage to cool EGR gas by a refrigerant having a second temperature lower than the first temperature;
Including
The second refrigerant passage includes a connection portion connected to the first refrigerant passage,
A valve capable of changing a direction of refrigerant flow between the first refrigerant passage and the second refrigerant passage;
The cooling device for an internal combustion engine according to claim 1, wherein the control means includes valve control means for controlling supply of the refrigerant to the second refrigerant passage by switching an open / close state of the valve.   The cooling apparatus for an internal combustion engine according to claim 2, wherein the second refrigerant passage is connected to the first refrigerant passage so as to bypass the second EGR cooler with the valve as a starting point.   The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the predetermined high load region is a load region where knocking of the internal combustion engine occurs.

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