JP2017057788A - Supercharging system for internal combustion engine with egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supercharging system capable of suppressing generation of condensation water in an intercooler 24 by effectively using an EGR device 30 and suitable for an engine with the EGR device.SOLUTION: A supercharging system in which a compressor of a supercharger and an intercooler 24 are provided in an intake passage of an engine 10 with an EGR device includes an ECU 60 for controlling a flow rate of cooling water. When the possibility that condensation water might be generated in the intercooler 24 is determined, by alleviating restriction of a flow rate of cooling water flowing in an EGR cooler 32 to a required flow rate, condensation water is actively generated in the EGR cooler 32. By discharging the condensation water to outside by a gas-liquid separator 33, humidity of the EGR gas itself is lowered. Thus, this can reduce the humidity of the entire supercharged air, so as to suppress generation of condensation water in the intercooler 24.SELECTED DRAWING: Figure 2

Description

  The present invention is suitable for an internal combustion engine (hereinafter referred to as an “engine”) mounted on a vehicle such as an automobile, particularly an engine equipped with an EGR (exhaust gas recirculation) device, so-called an engine with an EGR device. Supply system.

Engines equipped with EGR devices are widely used in vehicles for the purpose of reducing nitrogen oxides and improving fuel efficiency at partial load.
This EGR device is a system that recirculates a part of engine exhaust as EGR gas to the intake side, and includes an EGR cooler to cool and recirculate the EGR gas. Specifically, a water-cooled EGR cooler for exchanging heat of the EGR gas with cooling water is provided in the EGR passage that recirculates the EGR gas from the exhaust passage to the intake passage. And as a cooling water circulation path | route of this EGR cooler, the EGR cooler is arrange | positioned in the position which becomes a downstream of a cooling passage of an engine, and the cooling water which passed the cooling passage of the engine is supplied to an EGR cooler. .

However, although the above cooling path configuration is useful in that the cooling water for engine cooling can be efficiently used for cooling the EGR cooler, the following events are concerned.
That is, in the case of the above cooling path configuration, since the cooling water flow rate of the engine and the cooling water amount of the EGR cooler are dependent, the cooling water is supplied to the EGR cooler according to the required flow rate set based on the operating state of the engine. It will be (circulated). As a result, for example, when the cooling water temperature of the engine is low, condensed water is generated in the EGR cooler due to overcooling of the EGR gas, and various problems may be caused due to the condensed water.

Therefore, as one measure for suppressing the generation of condensed water in the EGR cooler, for example, a cooling system as described in Patent Document 1 has been proposed.
The cooling system includes a condensation determination unit that determines the possibility that condensed water is generated in the EGR cooler. When the condensation determination unit determines that there is a possibility of the generation of condensed water, the cooling water to the EGR cooler is determined. The circulation flow rate is limited to a smaller amount than the required flow rate of the engine, and the generation of condensed water in the EGR cooler can be suppressed.

JP 2014-141891 A

However, in recent years, as the performance of engines has increased, supercharging systems have been installed in various engines.
In this supercharging system, a supercharger (compressor) and an intercooler are arranged in series in the intake passage of the engine, so that the intake air to the engine is compressed by the supercharger and the compressed air (supercharged) This is a basic configuration for improving the engine output by cooling the (air supply) with an intercooler and supercharging the engine.

When considering that such a supercharging system is installed in the engine with the EGR device described above, in order to use the EGR gas as a part of the supercharged air, the EGR gas is upstream of the supercharger (compressor). However, in this case, the following new problems have been pointed out.

That is, it is a problem of condensed water generation in the intercooler. Even if the generation of condensed water in the EGR cooler can be suppressed by the above-described measures, the supercharged air containing the EGR gas will pass through the intercooler. It is feared to occur. In particular, the intercooler must be placed in the vicinity of the intake side of the engine. Therefore, a serious problem is caused by the scattering of condensed water downstream of the intercooler (water hammer, exhaust purification catalyst / exhaust sensor heat due to large amount of water suction). I am concerned about shocks.
Therefore, in the supercharging system applied to the engine with the EGR device, how to suppress the generation of condensed water in the intercooler is a current problem.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to make it possible to suppress the generation of condensed water in the intercooler by effectively utilizing the EGR device in an engine with an EGR device, To provide a supercharging system suitable for an engine with an EGR device.

[Means of Claim 1]
The invention according to claim 1 (supercharging system) is applied to an internal combustion engine with an EGR device, and supercharger and intercooler for supercharging and cooling intake air including EGR gas recirculated in an intake passage. It has a basic configuration.

And in this invention, the cooling medium for engine cooling and the cooling medium for EGR cooler cooling of an EGR apparatus are combined, and it has the following five means, It is characterized by the above-mentioned.
(1) A flow rate adjusting means for adjusting the circulating flow rate of the cooling medium to the EGR cooler.
(2) Required flow rate calculation means for calculating a required flow rate of the cooling medium based on the operating state of the engine.
(3) Condensation determination means for determining the possibility of generation of condensed water in the intercooler.
(4) When it is determined by this condensation determination means that condensed water is likely to be generated, the EGR cooler actively condenses without limiting the circulating flow rate of the cooling medium to the EGR cooler to a small amount with respect to the required flow rate. Control means for controlling the flow rate adjusting means to generate water.
(5) Means for discharging condensed water generated by the EGR cooler in the EGR passage of the EGR device to the outside.

According to the present invention having the above configuration, when it is determined that there is a possibility of generation of condensed water in the intercooler, the flow restriction on the required flow rate is relaxed for the cooling medium flowing in the EGR cooler, and the condensation is actively performed in the EGR cooler. By generating water and discharging the condensed water, the humidity of the EGR gas itself is reduced, and the generation of condensed water in the intercooler can be suppressed by reducing the humidity of the supercharged air.
Therefore, a supercharging system suitable for an engine with an EGR device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing an embodiment of a supercharging system equipped in a water-cooled engine with an EGR device, which is a typical application example of the present invention, and is used to explain the overall configuration of the engine system. Example). It is a schematic block diagram with which it uses for description of the cooling water path | route and cooling water flow control means in the said system (Example). It is a flowchart (example) which shows the procedure of the cooling water flow control means in the said system. It is a related figure used for calculation of basic demand flow in the above-mentioned procedure. It is a related figure used for calculation of the water temperature coefficient in the above-mentioned procedure. It is a related figure used for calculation of the condensation temperature in the above-mentioned procedure. It provides for explanation of calculation of the guard flow rate in the above procedure, (a) is a relationship diagram used for calculation of the upper limit guard flow rate, (b) is a relationship diagram used for calculation of the lower limit guard flow rate. It is a related figure used for calculation of the guard flow in the above procedure.

  Hereinafter, the best mode for carrying out the present invention will be described in detail according to embodiments shown in the drawings.

  The embodiment in the present embodiment shows a typical application example of the present invention, and an engine with an EGR device (internal combustion engine) mounted on a vehicle is constituted by a water-cooled multi-cylinder engine, In the case where the cooling water is also used as a cooling medium for cooling the EGR cooler of the EGR device, the embodiment is embodied as a preferred supercharging system.

In the following description, first, the basic configuration of the EGR device and the supercharging system and the relationship between the two devices will be outlined, and then the characteristic configurations and functions of the cooling water path and the cooling water flow rate control means will be sequentially described.
In each figure, the same or equivalent parts are denoted by the same reference numerals, and redundant description is omitted.

[Basic configuration of EGR device and supercharging system and relationship between the two devices]
In FIG. 1, a water-cooled engine 10 includes an engine body (hereinafter also referred to as “engine body”) 11 having multiple cylinders (for example, 4 cylinders), and an intake passage 12 and an exhaust passage 13 for each cylinder. Are connected.
The intake passage 12 introduces intake air (intake air) that is taken in from the air cleaner 14 and is metered by the throttle valve 15 into each cylinder, and the exhaust passage 13 is combustion gas (exhaust gas) exhausted from each cylinder. Gas) is purified by an exhaust purification catalyst (purification device) 16 and released to the outside.
A turbocharger 20 and an EGR device 30 are disposed across the intake passage 12 and the exhaust passage 13.

The turbocharger 20 includes a compressor 21, a turbine 22, and a connecting shaft 23 that integrally couples the compressor 21 and the turbine 22.
The compressor 21 is disposed on the downstream side of the air cleaner 14 in the intake passage 12, and the turbine 22 is disposed on the upstream side of the exhaust purification catalyst 16 in the exhaust passage 13. Therefore, the turbine 22 drives the compressor 21 using the exhaust gas as a power source, and the intake air to the engine 10 is compressed by the compressor 21.

  An intercooler 24 for cooling the air compressed by the compressor 21 is provided downstream of the compressor 21. Further, the throttle valve 15 described above is provided downstream of the intercooler 24.

  The EGR device 30 is a low-pressure loop system, and includes an EGR passage 31 that connects the exhaust passage 13 downstream of the exhaust purification catalyst 16 and the intake passage 12 upstream of the compressor 21. In the middle of the EGR passage 31, an EGR cooler 32, a gas-liquid separator 33, and an EGR valve 34 are provided in series in order from the upstream side of the flow of EGR gas when returning to the intake passage 12. The EGR cooler 32 is provided for cooling the EGR gas flowing through the EGR passage 31, and the EGR valve 34 is provided for adjusting the amount of EGR gas returned to the intake passage 12 through the EGR passage 31. It has been.

  Thus, the EGR gas recirculated by the EGR device 30 and the fresh air taken in from the air cleaner 14 are compressed by the supercharger 20 (compressor 21) and cooled by the intercooler 24 and supplied to the engine 10. Thus, the EGR gas always passes through the intercooler 24.

Among the above-described components, the relationship between the intercooler 24, the EGR cooler 32, and the gas-liquid separator 33 is a characteristic part of the present embodiment including the cooling water path for cooling each cooler. These functions will be described in detail later.

[Configuration of cooling water path]
In the present embodiment, as shown in FIG. 2, two cooling water paths 40 and 50 are provided as cooling water paths by circulating the cooling water. The first system is an engine cooling water path 40 through which cooling water that mainly cools the engine body 11 and the EGR cooler 32 of the engine 10 circulates, and the second system is cooling supplied to the intercooler 24. This is a cooling water path 50 dedicated to the intercooler through which water circulates.

First, the engine coolant passage 40 as the first system will be described with reference to FIG.
2, a mechanical water pump 41 that rotates using a driving force of a crankshaft (not shown) is attached to the engine body 11 of the engine 10, and this water pump 41 serves as a drive source. Thus, the cooling water is circulated through the cooling water passage 40.
The cooling water path 40 is bypassed from the water pump 41 via the engine body 11 → the radiator 42 and the main path (first circulation path) 40A through which the cooling water circulates and bypasses the radiator 42 for cooling. It has two paths, a bypass path (second circulation path) 40B through which water circulates.

The radiator 42 disposed in the main path 40A is attached to the front side of the vehicle, for example, and is used for cooling the cooling water with outside air. In addition, a water temperature sensor 43 that detects the temperature of the cooling water is provided on the upstream side of the water pump 41 in the main path 40A.
On the other hand, a heater core 44 serving as a heat source in the in-vehicle air conditioner and an EGR cooler 32 that cools EGR gas in the EGR device 30 are provided in series in the bypass path 40B.
A flow rate adjusting valve 45 that adjusts the flow rate of the cooling water flowing through the bypass route 40B is provided at a branch point between the main route 40A and the bypass route 40B.

Next, the cooling water path 50 dedicated to the intercooler which is the second system will be described. The cooling water path 50 is closed loop with the intercooler 24, the dedicated water pump 51 and the sub-radiator 52 as shown in FIG. Is built to form.
Here, for example, an electric type mounted on or near the engine body 11 is used as the water pump 51, and a small type attached to the back side of the radiator 42 is used as the sub-radiator 52, for example. .

[Configuration of cooling water flow rate control means]
Next, the control content by the cooling water flow rate control means will be described with reference to FIGS.
In FIG. 2, an ECU 60 serving as the center of the cooling water flow rate control means includes a well-known microcomputer including a CPU, a memory such as a ROM and a RAM, and executes various control programs stored in the ROM. Thus, various controls of this system are carried out according to the engine operating state and the like each time.

Specifically, although it is also introduced in Patent Document 1, it has a basic configuration and functions. That is, the ECU 60 includes, in addition to the water temperature sensor 43 described above, a rotation speed sensor 61 that detects the engine rotation speed, a load sensor 62 that detects the intake passage pressure as an engine load, and an outside air temperature sensor 63 that detects the outside air temperature. A humidity sensor 64 that detects the humidity of the outside air, an exhaust sensor 65 that detects the air-fuel ratio from the oxygen concentration of the exhaust, and the like are connected, and detection signals from these sensors are sequentially input to the ECU 60. Then, the ECU 60 performs flow rate control by adjusting the opening degree of the flow rate adjustment valve 45 based on the input various detection signals.
Here, it should be noted that in this embodiment, an intake air temperature sensor 53 for detecting the temperature on the outlet side of the intercooler 24 (outlet intake air temperature) is provided, and the detection signal of the intake air temperature sensor 53 is also input to the ECU 60. It is a point to be done.

  By the way, for example, when the temperature of the cooling water in the cooling water passage 50 dedicated to the intercooler is low, such as when the engine 10 is cold, when the cooling water is circulated through the intercooler 24, the supercharged air containing EGR gas is generated. There is a possibility that moisture in the supercharged air is condensed due to excessive cooling by the intercooler 24.

[Features of this embodiment]
Therefore, in the present embodiment, the possibility of the generation of condensed water in the intercooler 24 is determined, and when it is determined that the condensed water is likely to be generated, the EGR cooler 32 actively generates condensed water. It is characterized in that the flow rate of the cooling water to the EGR cooler 32 is adjusted and the flow rate control by the flow rate adjustment valve 45 is performed so that the adjusted flow rate is obtained.

  Since the main feature of this feature is the cooling water flow rate control performed by the ECU 60, the cooling water flow rate control procedure will be described with reference to the flowchart shown in FIG. This procedure is repeatedly performed by the ECU 60 at a predetermined cycle.

  In FIG. 3, in step S1, the required flow rate is calculated based on the engine operating state. At this time, the basic required flow rate is calculated based on the engine rotation speed and the engine load (torque) as the engine operating state, and the required flow rate is calculated as a result of performing the water temperature correction on the basic required flow rate. More specifically, based on the relationship shown in FIG. 4, the basic required flow rate is calculated such that the flow rate increases as the engine speed increases or the engine load (torque) increases. Further, based on the relationship shown in FIG. 5, the water temperature coefficient is calculated so that the numerical value increases as the cooling water temperature increases. Then, the final required flow rate is calculated by multiplying the basic required flow rate and the water temperature coefficient.

  In the subsequent step S2, the condensation temperature at which condensed water is generated in the intercooler 24 is calculated based on the outside air temperature and humidity. At this time, based on the relationship shown in FIG. 6, the condensation temperature is calculated such that the higher the humidity or the higher the outside air temperature, the higher the temperature.

In the subsequent step S3, the temperature on the outlet side of the intercooler 24 (outlet intake air temperature) is calculated based on the detection result of the intake air temperature sensor 53.

  Thereafter, in step S4, it is determined whether or not the outlet intake air temperature calculated in step S3 is lower than the condensation temperature calculated in step S2. If the outlet intake air temperature <condensation temperature, the process proceeds to step S5, and the guard flow rate is calculated. Here, as the guard flow rate, an upper limit guard flow rate (upper limit guard value) for limiting the required flow rate calculated in step S1 on the high flow rate side, and a lower limit guard flow rate (lower limit guard value) for limiting on the low flow rate side. These guard flow rates are calculated using water temperature, outside air temperature, and humidity as calculation parameters.

  Specifically, the upper limit guard flow rate and the lower limit guard flow rate are calculated using the relationship shown in FIGS. 7A and 7B for the water temperature and using the relationship shown in FIG. 8 for the outside air temperature and humidity. According to FIG. 7A, the lower limit guard flow rate is set to a smaller value as the water temperature is lower, and according to FIG. 7B, the lower limit guard flow rate is set to a larger value as the water temperature is lower. Further, according to FIG. 8, the higher the outside air temperature or the higher the humidity, the larger the guard correction value is calculated.

  Thereafter, in step S <b> 6, it is determined whether or not the cooling water is being radiated in the heater core 44. If the heater core 44 is in a heat dissipation state, the process proceeds to step S7, and if the heater core 44 is not in a heat dissipation state, the process proceeds to step S9.

In step S7, it is determined whether the required flow rate calculated in step S1 is larger than the upper limit guard flow rate calculated in step S5, or whether the required flow rate calculated in step S1 is smaller than the lower limit guard flow rate calculated in step S5. Then, if the required flow rate ≦ the upper limit guard flow rate and the required flow rate ≧ the lower limit guard flow rate, this processing is terminated as it is. In this case, the flow rate control of the cooling water is performed based on the required flow rate calculated in step S1.
If the required flow rate is higher than the upper guard flow rate, or if the required flow rate is lower than the lower guard flow rate, the process proceeds to step S8, and the required flow rate is limited by the upper limit guard flow rate or the lower limit guard flow rate. In this case, the flow rate control of the cooling water is performed at a limited flow rate.

  In step S9, it is determined whether the required flow rate calculated in step S1 is smaller than the lower limit guard flow rate calculated in step S5. If the requested flow rate is equal to or lower than the lower limit guard flow rate, the present process is terminated as it is. In this case, the flow rate control of the cooling water is performed based on the required flow rate calculated in step S1. If the required flow rate <the lower limit guard flow rate, the process proceeds to step S10, and the required flow rate is limited by the lower limit guard flow rate. In this case, the flow rate control of the cooling water is performed at a limited flow rate.

  Here, what is important is to prevent the flow rate with respect to the required flow rate of the cooling water flowing through the EGR cooler 32 from being restricted more than necessary when the intercooler 24 determines that there is a possibility of the generation of condensed water. That is, the EGR cooler 32 actively generates condensed water by supercooling the EGR gas.

Therefore, when the lower limit guard flow rate of the cooling water is set to a relatively high flow rate side and the intercooler 24 determines that there is a possibility of the generation of condensed water, the low flow rate is determined based on the comparison between the required flow rate and the lower limit guard flow rate. The flow rate on the side was not limited to a smaller amount than necessary. In addition, the EGR gas containing the condensed water generated in the EGR cooler 32 is configured such that the condensed water is separated and removed (discharged to the outside) in the gas-liquid separator 33 disposed on the downstream side of the EGR cooler 32. .
Thus, the EGR gas sequentially passes through the EGR cooler 32 and the gas-liquid separator 33, thereby removing moisture and lowering the humidity. So-called dehumidification is performed.
As a result, by supplying this low-humidity EGR gas to the intake passage 12, the humidity of the entire supercharged air can be reduced, and the generation of condensed water in the intercooler 24 can be suppressed.

[Effect of this embodiment]
According to the embodiment described in detail above, the following excellent effects can be obtained.

(1) First, it is provided with condensation determination means for determining the possibility of the generation of condensed water in the intercooler 24, and when it is determined that the condensed water is likely to be generated in the intercooler 24, the EGR cooler 32 The flow restriction for the required flow rate is eased for the flowing cooling water.
Second, a gas-liquid separator 33 is provided on the downstream side of the EGR cooler 32, and condensed water generated in the EGR cooler 32 is removed (discharged to the outside).
Accordingly, the condensed water is positively generated in the EGR cooler 32 to reduce the humidity of the EGR gas itself, and the humidity of the supercharged air is reduced. Therefore, the generation of condensed water in the intercooler 24 can be suppressed. It becomes. As a result, various problems due to the generation of condensed water in the intercooler 24 can be solved all at once.

(2) Condensed water generation in the intercooler 24 is suppressed by skillfully utilizing the characteristics of the EGR gas that forms part of the supercharged air. For this reason, it is possible to construct the system by maximally effectively utilizing the existing EGR device 30.
Therefore, a supercharging system suitable for an engine with an EGR device can be obtained.

[Modifications; Other Examples]
As mentioned above, although one Example of this invention was explained in full detail, it can change variously in the range which does not deviate from the mind of this invention, The modification is illustrated below as another Example.

(1) In the above embodiment, the heater core 44 is used as a heat exchanger that releases the heat of the cooling water (cooling medium), but this is changed and an oil warmer that warms the lubricating oil is used as the heat exchanger. Is also possible. In this case, for example, an oil warmer is provided in place of the heater core 44 in the bypass path 40B shown in FIG.

(2) In the above embodiment, the temperature at the outlet side of the intercooler 24 (outlet intake air temperature) is calculated based on the detection result of the intake air temperature sensor 43, but the present invention is not limited to this.
For example, the outside air temperature, the outlet side gas temperature of the EGR cooler 32, the EGR gas amount, the EGR rate of the EGR device 30, the supercharging pressure of the supercharger 20, the inlet side cooling water temperature of the intercooler 24, the required flow rate of the intercooler 24, etc. It is possible to calculate the outlet intake air temperature of the intercooler 24 based on various calculation parameters.

(3) In the above embodiment, the condensing temperature at which the condensed water is generated in the intercooler 24 is calculated based on the outside air temperature and humidity. However, as calculation parameters, the air-fuel ratio of the intake air and the EGR of the EGR device 30 are used. A rate may be added.

(4) In the above embodiment, the water pump 41 is a mechanical water pump driven by the engine 10, but an electric water pump may be used instead. In this case, it is possible to use a configuration in which the water pump is used as a flow rate adjusting unit and the flow rate is controlled by controlling the driving of the water pump.

(5) In the above embodiment, the cooling water passage 50 is used for cooling the intercooler 24 and the flow rate of the cooling water is not particularly adjusted. Alternatively, the flow rate can be adjusted by utilizing the electric water pump 51 as the flow rate adjusting means. But it can replace with the cooling water path 50 for exclusive use, and can also comprise so that the cooling water of the engine 10 may be utilized.

(6) In the above embodiment, the cooling water is used as the cooling medium. However, instead of this, other fluids such as oil can be used as the cooling medium.
In particular, as the intercooler, an air-cooled intercooler that uses air as a cooling medium can be used instead of the water-cooled intercooler 24. Since this air-cooled type cools by using the traveling wind of the vehicle, the wind speed can be used as one of the calculation parameters when calculating the outlet intake air temperature of the intercooler 24.

(7) In the above embodiment, the gas-liquid separator 33 is disposed downstream of the EGR cooler 32 as the condensed water discharge means for discharging the condensed water generated in the EGR cooler 32 to the outside in the EGR passage 31 of the EGR device 30. However, the gas-liquid separator 33 may be incorporated in the EGR cooler 32. Instead of using the gas-liquid separator 33, a drain mechanism for discharging condensed water to the outside may be provided in the EGR cooler 32 itself.

(8) In the above embodiment, the case where one EGR cooler 32 is used has been described in detail, but a plurality of EGR coolers may be combined. For example, two EGR coolers may be arranged in series, and at least one of the flow rate of the cooling medium flowing through the upstream EGR cooler and the cooling medium flowing through the downstream EGR cooler may be adjusted. In this case, in particular, condensate is actively generated in the upstream EGR cooler, and after removing the condensate, the downstream EGR cooler is cooled to an optimum EGR gas temperature according to the operating conditions of the engine. When the medium is controlled, it is possible to realize a more favorable air-fuel mixture state while preventing generation of condensed water in the intercooler 24, and to improve the combustion state of the engine. Of course, the same effect can be obtained by connecting a plurality of EGR coolers in parallel and appropriately controlling the amount of EGR gas passing through each EGR cooler and the flow rate of the cooling medium flowing through each EGR cooler. .
Further, when a plurality of EGR coolers are provided, the flow path of the cooling medium flowing through each EGR cooler may be common or separately provided. For example, the case where the cooling medium is the cooling water will be described. Since the temperature of the cooling water varies greatly depending on the position of the circulation path, the cooling water path is branched from the position of the circulation path that is in a desirable temperature range for each EGR cooler. Therefore, it is easy to achieve both the removal of condensed water and the optimal mixture. More specifically, in the case where two EGR coolers are arranged in series, the upstream EGR cooler is caused to flow with cooling water at a lower temperature than the downstream EGR cooler to actively generate condensed water, and the downstream side An optimal air-fuel mixture state can be realized by flowing cooling water having a temperature higher than that of the upstream EGR cooler to the EGR cooler. When branching from different positions is not possible, a method of connecting the cooling water channel outlet of the upstream EGR cooler and the cooling water inlet of the downstream EGR cooler may be used. In addition, the effect of flowing cooling water at a higher temperature than the upstream EGR cooler to the downstream EGR cooler is to prevent the situation where the mixture temperature becomes too low and the combustion worsens, and to increase the EGR gas pressure downstream of the EGR cooler. Thus, it is possible to expect an effect such that the EGR gas easily recirculates to the intake side.

DESCRIPTION OF SYMBOLS 10 ... Water-cooled engine (internal combustion engine), 12 ... Intake passage, 13 ... Exhaust passage, 20 ... Turbocharger, 21 ... Compressor, 22 ... Turbine, 24 ... Water-cooled intercooler, 30 ... EGR device, 31 ... EGR passage, 32 ... water-cooled EGR cooler, 33 ... gas-liquid separator (condensate discharge means), 40 ... engine cooling water path, 40A ... main path (first circulation path), 40B ... bypass path (second (Circulation path), 45 ... flow rate adjusting valve (flow rate adjusting unit), 60 ... ECU (required flow rate calculating unit, condensation determining unit, control unit).

Claims (4)

The present invention is applied to an internal combustion engine with an EGR device equipped with an EGR device (30) for recirculating a part of exhaust discharged from the internal combustion engine (10) to the intake passage (12) as EGR gas, and is recirculated in the intake passage. A supercharging system having a supercharger (20) and an intercooler (24) for supercharging and cooling intake air containing said EGR gas,
A first circulation path (40A) for circulating a cooling medium for cooling the internal combustion engine;
A second circulation path (40B) for circulating the cooling medium to cool the EGR cooler (32) of the EGR device;
A flow rate adjusting means (45) for adjusting a circulating flow rate of the cooling medium flowing through the EGR cooler in the second circulation path;
Required flow rate calculation means (60) for calculating a required flow rate of the cooling medium based on an operating state of the internal combustion engine;
Condensation determination means (60) for determining the possibility of generation of condensed water in the intercooler;
Control means (60) for controlling the flow rate adjusting means so as to change the circulating flow rate of the cooling medium from the required flow rate when it is determined by the condensation determination means that condensed water may be generated;
Condensed water discharge means (33) for discharging condensed water generated in the EGR cooler to the outside in the EGR passage (31) of the EGR device;
A supercharging system for an internal combustion engine with an EGR device. The supercharging system for an internal combustion engine with an EGR device according to claim 1,
The control means includes
Means for setting a lower limit guard value as a flow rate limit value for the circulating flow rate of the cooling medium;
When it is determined by the condensation determination means that there is a possibility of the generation of condensed water, based on the comparison between the required flow rate calculated by the required flow rate calculation means and the lower limit guard value, Means to enforce the restrictions;
A supercharging system for an internal combustion engine with an EGR device. The supercharging system for an internal combustion engine with an EGR device according to claim 1 or 2,
Condensation temperature calculation means (60, 64) for calculating a condensation temperature at which condensed water is generated in the intercooler;
Intake air temperature calculating means (53, 60) for calculating the temperature of the intake air passing through the intercooler;
With
The condensing determination means determines the possibility of the generation of the condensed water by comparing the intake air temperature calculated by the intake air temperature calculating means with the condensing temperature calculated by the condensing temperature calculating means. A supercharging system for an internal combustion engine with a device. In the supercharging system of the internal combustion engine with an EGR device according to any one of claims 1 to 3,
The supercharging system for an internal combustion engine with an EGR device, wherein the condensed water discharge means is a gas-liquid separator (33) disposed downstream of the EGR cooler in the EGR passage.