JP2003328864A - Exhaust gas recirculation device, heat exchanger used for exhaust gas recirculation device, and internal combustion engine - Google Patents

Abstract

(57) Abstract: An exhaust recirculation device and an internal combustion engine that have a simple configuration and are capable of adjusting the temperature of recirculated exhaust gas that is recirculated to an intake passage depending on the state of intake air, and an internal combustion engine. Provided is a heat exchanger that can easily adjust the temperature of the recirculated exhaust gas. An EGR device (31) for recirculating a part of exhaust gas downstream of a turbocharger (23) to an intake passage (16) upstream of the turbocharger (23) is provided. This EGR device 31
The center side is a heat insulation passage 35, and the outer periphery is a cooling passage 36.
Is provided. A metering valve 34 for adjusting the opening based on the temperature of the intake air upstream of the turbocharger 23 is provided at the outlet of the recirculated exhaust gas in the heat exchanger 33. By adjusting the mixing ratio between the high-temperature exhaust gas and the low-temperature exhaust gas by adjusting the opening of the metering valve 34, the temperature of the intake air supplied into the combustion chamber 14 is changed, and the exhaust gas Adjust the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation system for returning a part of exhaust gas discharged from a combustion chamber to an intake passage through which intake air supplied to the combustion chamber passes. Further, the present invention is used in an exhaust gas recirculation device,
The present invention relates to a heat exchanger that adjusts the temperature of exhaust gas that is recirculated. Furthermore, the present invention relates to an internal combustion engine having a supercharger for supplying supercharged air to a combustion chamber and an exhaust gas recirculation device.

[0002]

2. Description of the Related Art In this type of exhaust gas recirculation device, an exhaust passage through which exhaust gas discharged from a combustion chamber of an internal combustion engine passes and an intake passage through which intake air supplied to the combustion chamber passes. An exhaust gas recirculation passage is formed.

Here, the exhaust gas discharged from the combustion chamber has a considerably high temperature during normal operation. Therefore, if this high-temperature exhaust gas is recirculated to the intake passage as it is, the temperature of the intake air supplied into the combustion chamber becomes too high, and the efficiency of filling the combustion chamber may decrease. In particular, in an internal combustion engine equipped with a supercharger, the temperature of the intake air greatly rises when passing through the supercharger. Therefore, from the viewpoint of durability of the supercharger, the mixed gas ( Here, it is desirable to lower the temperature of the mixed gas of the air and the recirculated exhaust gas. For this reason, an EGR cooler for cooling the recirculated exhaust gas passing through the exhaust gas recirculation passage is provided in the middle of the exhaust gas recirculation passage.

[0004]

However, in the above-mentioned conventional structure, the temperature of the exhaust gas discharged from the combustion chamber becomes low because the intake air temperature is too low, for example, during cold start. Further, in such a low temperature environment, immediately after the start of the internal combustion engine, the internal combustion engine is not sufficiently warmed up,
The temperature of the exhaust gas also does not rise easily. For this reason,
Even if a part of the exhaust gas is recirculated to the intake passage, the recirculated exhaust gas is cooled by the EGR cooler, so that the temperature becomes low and it is difficult to immediately raise the intake air temperature.
As a result, it takes a long time for the catalyst heated by the exhaust gas to reach the activation temperature, which deteriorates the initial emission.

Particularly, in a vehicle equipped with a diesel engine, in recent years, in order to further improve the exhaust gas purification performance, a diesel particulate filter (DP) is used.
F) is being worn. Further, the diesel engine is equipped with a nitrogen oxide storage catalyst (NOx storage catalyst) that reduces the concentration of nitrogen oxides in the exhaust gas. In this DPF or NOx storage catalyst, it is necessary to expose it to high-temperature exhaust gas to desorb or decompose adsorbed particulates or adsorbed sulfur oxides in order to regenerate its purifying ability after a predetermined period. .

Here, in the diesel engine equipped with the exhaust gas recirculation device of the conventional structure, the DPF and NO
x When regenerating the storage catalyst, for example, when the engine is operated in the low load region, the exhaust gas recirculated to the intake side is cooled by the EGR cooler, so the exhaust temperature is maintained high enough for regeneration. Can not do. Therefore, it is necessary to increase the unburned fuel content in the exhaust gas by increasing the fuel injection amount and burn the unburned fuel content on the DPF or the catalyst to heat the DPF or the catalyst. . Then, there is a problem that the fuel efficiency of the diesel engine is significantly deteriorated as the fuel injection amount increases.

Further, with the advent of the direct injection type gasoline engine, the NOx storage catalyst has come to be mounted also on the gasoline engine. Even in such a gasoline engine, when the regeneration timing of the NOx storage catalyst overlaps at the cold start, the exhaust gas recirculated to the intake side becomes E.
Since it is cooled by the GR cooler, the exhaust gas temperature cannot be maintained high enough for regeneration. Therefore, N
There is a possibility that the Ox storage catalyst may not be sufficiently regenerated.

In order to solve such a problem, the invention disclosed in, for example, Japanese Patent Laid-Open No. 2000-240437 can be used. In the internal combustion engine described in this publication, a part of air in the intake pipe or a mixed gas of air and recirculated exhaust gas is guided, fuel is injected into the air or the mixed gas to burn, and high temperature combustion is performed. It is equipped with a combustion heater that generates gas. Then, when it is necessary to immediately raise the temperature of the exhaust gas during regeneration of the catalyst, the high temperature combustion gas generated in the combustion heater is supplied to the upstream side of the catalyst in the exhaust pipe to control the temperature of the exhaust gas. It is designed to increase.

However, an internal combustion engine equipped with such a combustion heater has a problem that the structure thereof is significantly complicated and the manufacturing cost is increased. Also,
Since the fuel is used to raise the exhaust gas temperature when the catalyst is regenerated, there is a problem that fuel efficiency deteriorates.

The present invention has been made in view of the above circumstances, and its object is to provide a simple structure for the recirculated exhaust gas recirculated to the intake passage side in accordance with the state of intake air supplied to the internal combustion engine. An object of the present invention is to provide an exhaust gas recirculation device and an internal combustion engine that can adjust the temperature. Another object of the present invention is to provide a heat exchanger suitable for the exhaust gas recirculation device, which has a simple structure and can easily adjust the temperature of the recirculated exhaust gas.

[0011]

[Means for Solving the Problems] Means for attaining the above-mentioned objects and their effects will be described below. The invention described in claim 1 is an exhaust gas recirculation passage for recirculating a part of exhaust gas discharged from a combustion chamber of an internal combustion engine into an intake passage through which intake air supplied into the combustion chamber passes, and an intake passage thereof. An exhaust gas recirculation device having a temperature adjuster for adjusting the temperature of the recirculated exhaust gas recirculated therein, wherein the temperature adjuster has a heat retaining passage for allowing at least a part of the recirculated exhaust gas to pass while retaining heat. A cooling passage through which at least a part of the recirculation exhaust gas passes while cooling; and a recirculation exhaust gas that passes through the heat retention passage and a recirculation exhaust gas that passes through the cooling passage, individually or in a mixture, and guides them to the intake passage. A metering device, wherein the metering device is configured such that, according to temperature information of intake air supplied to the internal combustion engine, the high temperature recirculation exhaust gas passing through the heat retaining passage and the low temperature recirculation exhaust gas passing through the cooling passage. Moth By adjusting the mixing ratio between, and wherein the directing recirculated exhaust gas into the intake passage.

According to the above construction, at least a part of the recirculated exhaust gas recirculated to the intake passage is recirculated to the intake passage while passing through the heat retaining passage while being in the high temperature state discharged from the combustion chamber. On the other hand, at least a part of the recirculation exhaust gas recirculated to the intake passage is recirculated to the intake passage in a low temperature state where it is cooled by passing through the cooling passage. Then, in the metering device, the mixing ratio of the high-temperature recirculated exhaust gas and the low-temperature recirculated exhaust gas is adjusted according to the temperature information of the intake air supplied to the internal combustion engine, and the recirculated exhaust gas recirculated to the intake passage is adjusted. The temperature is changed.

Here, for example, when the internal combustion engine is not warmed up sufficiently because the temperature of the intake air taken from the outside air is low, such as during cold start, when the operating state of the internal combustion engine is in the low load region, etc. The temperature of the exhaust gas discharged from the combustion chamber may not reach the regeneration temperature of the DPF or NOx storage catalyst. In such a case, the metering device recirculates only the relatively high-temperature recirculated exhaust gas that has passed through the heat retention passage to the intake passage. As a result, the temperature of the intake air after the recirculation exhaust gas is mixed is raised, and the temperature of the exhaust gas can be raised quickly by the combustion of the fuel in the combustion chamber.

On the other hand, for example, when the outside air temperature is high, the internal combustion engine is sufficiently warmed up, and the operating state of the internal combustion engine is in the high load region, the temperature of the exhaust gas becomes high. If the high-temperature exhaust gas is recirculated to the intake passage as it is in this state, the temperature of the intake air becomes too high, and the charging efficiency of the internal combustion engine may decrease. In such a case, the metering device allows only the sufficiently cooled low-temperature recirculation exhaust gas to recirculate through the cooling passage to the intake passage. As a result, it is possible to prevent the temperature of the intake air after the recirculation exhaust gas is mixed from becoming excessively high, and to suppress the decrease in the charging efficiency of the internal combustion engine.

Thus, by adjusting the mixing ratio of the high-temperature recirculation exhaust gas that has passed through the heat-retaining passage and the low-temperature recirculation exhaust gas that has passed through the cooling passage by means of the volume adjuster in accordance with the temperature condition of the intake air. , It becomes possible to adjust the intake air to a required temperature state. Then, the temperature of the exhaust gas can be controlled more appropriately by adjusting the temperature of the intake air according to the operating state of the internal combustion engine, the warm-up state, the surrounding environment, the regeneration request of the DPF or the NOx storage catalyst, and the like. it can.

According to a second aspect of the present invention, in the exhaust gas recirculation system according to the first aspect, the regulator is an intake passage upstream of a supercharger for supercharging the intake air supplied to the combustion chamber. The mixing ratio of the high-temperature recirculation exhaust gas passing through the heat retaining passage and the low-temperature recirculation exhaust gas passing through the cooling passage is adjusted according to the temperature information of the mixed gas inside.

According to the above configuration, it is possible to control the temperature of the intake air supplied to the supercharger. Therefore, when high-temperature intake air is supplied, it is prevented that the temperature of the intake air is adiabatically compressed in the supercharger and rises unexpectedly, affecting the compressor wheel of the supercharger. be able to.

According to a third aspect of the present invention, in the exhaust gas recirculation device according to the first aspect, the regulator is estimated based on temperature information of the mixed gas in the intake passage downstream of the supercharger. According to the temperature information of the mixed gas on the upstream side of the supercharger, it is possible to adjust the mixing ratio of the high-temperature recirculation exhaust gas that has passed through the heat retention passage and the low-temperature recirculation exhaust gas that has passed through the cooling passage. Characterize.

With the above structure, the same operational effect as the invention according to the second aspect can be obtained. According to a fourth aspect of the present invention, in the exhaust gas recirculation device according to any one of the first to third aspects, the exhaust gas supplied to the exhaust gas recirculation passage is included in a state of being discharged from the combustion chamber. It is characterized in that it is the exhaust gas that has passed through the contained component reducing device that reduces the amount of particulates.

According to the above-mentioned structure, it is possible to suppress the deposition of the deposits derived from the particulates discharged from the combustion chamber on the surfaces of the components of the exhaust gas recirculation device, the supercharger and the internal combustion engine. . Therefore, the durability of the exhaust gas recirculation device, the supercharger, and the internal combustion engine can be improved.

According to a fifth aspect of the present invention, in the exhaust gas recirculation device according to any one of the first to fourth aspects, the heat-retaining passage and the cooling passage are inside a heat exchanger having a double pipe structure. And the heat insulation passage is arranged on the center side,
The cooling passage is provided so as to cover at least a part of the outer peripheral surface of the heat retaining passage.

According to the above structure, at least a part of the outer peripheral surface of the heat retaining passage is covered with the cooling passage, so that the exhaust gas in the heat retaining passage is in contact with the cooling medium while the exhaust gas in the heat retaining passage is in the cooling passage. The exhaust gas can provide air insulation to the outside air. Therefore, the exhaust gas in the cooling passage can be efficiently cooled and the exhaust gas in the heat retaining passage can be effectively kept warm. Further, the heat exchanger provided with the heat retaining passage and the cooling passage can be configured in a simple and compact manner.

According to a sixth aspect of the present invention, in the exhaust gas recirculation device according to the seventh aspect, the heat radiating means for releasing the heat of the exhaust gas in the cooling passage to the outside on the outer peripheral surface of the cooling passage. Is provided.

With the above arrangement, the exhaust gas in the cooling passage can be cooled more efficiently. According to a seventh aspect of the present invention, in the exhaust gas recirculation device according to the sixth aspect, the heat radiating means is a heat radiating plate that bulges into the outside air from the outer surface of the cooling passage.

According to the above structure, the exhaust gas in the cooling passage can be efficiently cooled with a very simple structure. The invention according to claim 8 is the exhaust gas recirculation device according to any one of claims 5 to 7, wherein exhaust gas in the heat retaining passage and cooling are provided in a partition wall between the heat retaining passage and the cooling passage. It is characterized in that a heat insulating means for suppressing heat transfer with the exhaust gas in the passage is provided.

According to the above construction, heat transfer between the exhaust gas in the heat retention passage and the exhaust gas in the cooling passage is suppressed, and the heat retention of the exhaust gas in the heat retention passage and the cooling efficiency of the exhaust gas in the cooling passage are improved. Can be improved together.

The invention described in claim 9 is the exhaust gas recirculation apparatus according to any one of claims 5 to 8, wherein when the exhaust gas in the heat retention passage is exclusively supplied into the intake passage. Is characterized in that the regulator closes the outlet of the exhaust gas in the cooling passage to retain the exhaust gas in the cooling passage.

According to the above structure, the heat retaining effect of the exhaust gas in the heat retaining passage can be further enhanced. According to a tenth aspect of the present invention, in the exhaust gas recirculation apparatus according to any one of the first to ninth aspects, a supercharger for supercharging the recirculated exhaust gas with intake air supplied to the combustion chamber is provided. The exhaust gas passage on the downstream side is returned to the intake passage on the upstream side of the supercharger.

According to the above structure, the exhaust pressure applied to the turbine of the supercharger does not decrease due to the introduction of the recirculated exhaust gas into the exhaust gas recirculation device. Therefore, regardless of the operating state of the internal combustion engine, a predetermined rotational force can be applied to the turbine and a predetermined boost pressure can be generated from the low load region to the high load region. As a result, even in the partial high load region to the high load region, sufficient air is sucked into the combustion chamber, and the generation of particulates is suppressed. Then, it becomes possible to increase the recirculation amount of the exhaust gas, and it is possible to reduce the amount of nitrogen oxides discharged from the combustion chamber.

Further, the rotational speed of the turbine in the supercharger can be maintained high in accordance with the exhaust pressure from the combustion chamber. Therefore, when there is a sudden load increase request to the internal combustion engine, the supercharging pressure can be raised rapidly, and the transient response delay to the load request can be reduced. Then, the occurrence of transient air shortage is suppressed, the fuel injection amount can be increased, and the transient acceleration performance can be improved.

The invention as set forth in claim 11 is directed to an exhaust gas recirculation device for recirculating a part of exhaust gas discharged from a combustion chamber of an internal combustion engine into an intake passage through which intake air supplied into the combustion chamber passes. A heat exchanger disposed in the exhaust gas recirculation passage, wherein a heat retaining passage for allowing at least a portion of the recirculation exhaust gas recirculated in the intake passage to pass while retaining the temperature, and cooling at least a portion of the recirculation exhaust gas And a cooling passage to be passed through while keeping the heat-retaining passage on the center side and forming the double-pipe structure in which the cooling passage is provided so as to cover at least a part of the outer peripheral surface of the heat-retaining passage. Is characterized by.

According to the above-mentioned structure, substantially the same effect as the invention according to the fifth aspect can be obtained. According to a twelfth aspect of the present invention, in the heat exchanger used in the exhaust gas recirculation apparatus according to the eleventh aspect, the heat of the exhaust gas in the cooling passage is released to the outside on the outer peripheral surface of the cooling passage. It is characterized in that a heat dissipation means is provided.

According to the above construction, substantially the same effects as the invention of the sixth aspect are exhibited. According to a thirteenth aspect of the present invention, in the heat exchanger used in the exhaust gas recirculation apparatus according to the twelfth aspect, the heat radiating means is a heat radiating plate that bulges into the outside air from the outer surface of the cooling passage. It is characterized by

According to the above construction, substantially the same action and effect as the invention according to the seventh aspect can be obtained. According to a fourteenth aspect of the present invention, in the heat exchanger used in the exhaust gas recirculation device according to any one of the eleventh to thirteenth aspects, the heat insulation is provided in a partition wall between the heat insulation passage and the cooling passage. It is characterized in that heat insulating means for suppressing heat transfer between the exhaust gas in the passage and the exhaust gas in the cooling passage is provided.

According to the above construction, substantially the same effect as the invention according to the eighth aspect can be obtained. The invention according to claim 15 is an internal combustion engine having an exhaust gas recirculation device that recirculates a part of the exhaust gas discharged from the combustion chamber into the intake passage, and the invention according to any one of claims 1 to 10. An exhaust gas recirculation device as described is provided.

According to the above structure, in the internal combustion engine provided with the exhaust gas recirculation device, almost the same actions and effects as those of the inventions according to claims 1 to 10 are exhibited. Therefore, the temperature of the intake air is adjusted as necessary, the warm-up performance of the internal combustion engine is improved, the exhaust gas purifying catalyst is activated early, and the DPF and the NOx storage catalyst can be operated without complicating the structure of the internal combustion engine. It is possible to improve the reproduction performance.

According to a sixteenth aspect of the present invention, in the internal combustion engine according to the fifteenth aspect, a supercharger for supercharging the intake air supplied to the combustion chamber is provided, and the supercharger is disposed in the supercharger. The compressor wheel for increasing the pressure of the intake air is made of aluminum or aluminum alloy.

According to the above configuration, the temperature of the intake air supplied to the supercharger can be controlled, so that the intake air can be raised above the heat resistant temperature of the compressor wheel by adiabatic compression in the supercharger. It can be avoided in advance.
Therefore, the present invention is particularly suitable for an internal combustion engine provided with a supercharger having a compressor wheel made of aluminum or an aluminum alloy, which is used under severe conditions at high temperatures.

According to a seventeenth aspect of the present invention, in the internal combustion engine according to the fifteenth aspect, a supercharger for supercharging the intake air supplied into the combustion chamber is provided, and the supercharger is arranged in the supercharger. The compressor wheel for increasing the intake pressure is made of ceramics.

According to the above construction, the heat resistance of the compressor wheel can be improved, and higher temperature intake air can be supplied to the supercharger. Therefore, it is possible to increase the amount of high-temperature exhaust gas recirculated to the intake passage and improve the warm-up performance of the internal combustion engine. Further, when the internal combustion engine is operating in the low load region, DPF and NOx
It is possible to quickly shift the storage catalyst to a regenerable state.

The invention according to claim 18 is the invention according to claims 15 to
The internal combustion engine according to any one of 17 above, further comprising a fuel injection device that directly injects fuel into the combustion chamber.

In an internal combustion engine that directly injects fuel into the combustion chamber regardless of whether it is a diesel engine or a gasoline engine,
A large amount of nitrogen oxides, sulfur oxides and particulates are generated. Therefore, the present invention is particularly effective for such a direct injection type internal combustion engine.

According to a nineteenth aspect of the present invention, in the internal combustion engine according to the eighteenth aspect, an intake throttle valve for restricting intake air passing through the intake passage is provided in the intake passage.

According to the above construction, when the operating state of the internal combustion engine is in the low load region, the intake throttle valve restricts the amount of intake air taken in from the outside air, and more hot recirculated exhaust gas is introduced into the intake passage. The temperature of the exhaust gas discharged from the combustion chamber can be raised more quickly by recirculating the exhaust gas to the exhaust gas.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION An internal combustion engine 11 centered on a diesel engine, and an exhaust gas recirculation device (hereinafter referred to as an "EGR device") arranged in the internal combustion engine 11 according to the present invention will be described below.
An embodiment embodied in the heat exchanger 31 and the heat exchanger 33 will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, a piston 13 is reciprocally housed inside a cylinder 12 of an internal combustion engine 11, and a combustion chamber 14 is defined in the cylinder 12 by the piston 13. A fuel injection valve 15 as a fuel injection device that injects fuel into the combustion chamber 14 is disposed in the combustion chamber 14, and an intake passage 16 that guides intake air into the combustion chamber 14 and a fuel injection valve in the combustion chamber 14 are provided. An exhaust passage 17 for discharging exhaust gas generated by combustion to the outside is connected.

One end of the intake passage 16 is an air intake 18 which is opened to the outside air, and an air cleaner 19 for removing dust and the like from the intake air is provided near the air intake 18 of the intake passage 16. ing. An intake throttle valve 20 that adjusts the amount of air flowing through the intake passage 16 is provided downstream of the air cleaner 19 in the intake passage 16.

The exhaust passage 17 is provided with a diesel particulate filter (hereinafter referred to as "DPF") 21 as a contained component reducing device. The DPF 21 removes particulates contained in the exhaust gas discharged from the combustion chamber 14. Further, downstream of the DPF 21 in the exhaust passage 17, NO that occludes and decomposes nitrogen oxides discharged from the combustion chamber 14.
An x storage catalyst 22 is provided. A muffler (not shown) is provided downstream of the NOx storage catalyst 22 in the exhaust passage 17, and the exhaust passage 17 is open to the atmosphere further downstream thereof.

The intake passage 16 and the exhaust passage 17 are used as a supercharger that utilizes the energy of the exhaust gas passing through the exhaust passage 17 to compress the intake air into the combustion chamber 14 and supercharge it. The turbocharger 23 is provided. The turbocharger 23 includes a turbine housing 25 that houses a turbine wheel 24 that is rotated by exhaust gas, and a compressor housing 2 that houses a compressor wheel 26 that is integrally rotated with the turbine wheel 24 and compresses intake air, for example, made of an aluminum alloy.
7 and 7. Here, the compressor housing 27 is arranged in the intake passage 16 between the intake throttle valve 20 and the cylinder 12. The turbine housing 25 is arranged in the exhaust passage 17 between the cylinder 12 and the DPF 21.

An intercooler 28 with a bypass function is provided on the intake passage 16 downstream of the compressor housing 27. This intercooler 2
The reference numeral 8 serves to cool the intake air heated by the adiabatic compression in the turbocharger 23 and increase the efficiency of filling the combustion chamber 14 with the intake air. Further, the bypass function of the intercooler 28 is adapted to be activated when it is necessary to supply high-temperature intake air into the combustion chamber 14 as well as during cold start, for example.

Further, the DPF 21 and the NOx storage catalyst 2
The EGR device 31 connects the exhaust passage 17 between the intake valve 2 and the intake passage 16 between the intake throttle valve 20 and the turbocharger 23. This EGR device 31 is
A recirculation passage 32 as an exhaust recirculation passage for recirculating a part of the exhaust gas passing through the exhaust passage 17 to the intake passage 16.
A heat exchanger 33 for adjusting the temperature state of the recirculated exhaust gas passing through the recirculation passage 32, and a metering valve 3 as a regulator.
4 and. That is, in the internal combustion engine 11, a part of the exhaust gas downstream of the turbine wheel 24 of the turbocharger 23 is recirculated to the upstream of the compressor wheel 26 via the EGR device 31.

The heat exchanger 33 has a heat retaining passage 3 on the center side.
5 and a cooling passage 36 that covers the outer peripheral surface of the heat retaining passage 35 over the entire length, forming a double pipe structure. The partition wall 37 between the heat retaining passage 35 and the cooling passage 36 is made of a heat insulating material 38 as a heat insulating means made of, for example, a ceramic tube. Further, the cooling passage 36 is formed with a large number of heat radiation plates 39 as heat radiation means so as to bulge into the outside air from the outer surface thereof. And
In this heat exchanger 33, the recirculation exhaust gas passing through the heat retaining passage 35 is kept in a high temperature state by suppressing the heat radiation due to the air heat insulating effect of the exhaust gas in the cooling passage 36 and the heat insulating effect of the heat insulating material 38. To be done. On the other hand, the cooling passage 36
The exhaust gas passing through the inside is cooled by its heat being released to the outside air through the outer surface of the cooling passage 36 and the heat radiating plate 39, and shifts to a low temperature state.

The metering valve 34 is, for example, a three-way switching valve, and is provided so as to be joined to the end portion of the heat exchanger 33 on the intake passage 16 side. The metering valve 34 is opened based on the temperature of the intake air upstream of the compressor housing 27 measured by the intake air temperature sensor 40 under the control of an engine control unit (hereinafter referred to as “ECU”) 41. The degree is adjusted. By adjusting the opening degree of the metering valve 34, in the recirculation exhaust gas recirculated to the intake passage 16, the mixing ratio of the high temperature exhaust gas passing through the heat retaining passage 35 and the low temperature exhaust gas passing through the cooling passage 36. Is adjusted. And this EGR device 3
In No. 1, the temperature of the recirculation exhaust gas recirculated to the intake passage 16 is adjusted by adjusting the mixing ratio of the high temperature recirculation exhaust gas and the low temperature recirculation exhaust gas. Then, the temperature-controlled recirculated exhaust gas is supplied to the intake passage 1
6 is mixed with intake air from the air intake 18 and is supplied into the combustion chamber 14 in a compressed state via the turbocharger 23.

Next, the control of the metering valve 34 will be described. First, when the internal combustion engine 11 is cold started, the temperature of the outside air taken in from the air intake 18 is low, and the intake air temperature sensor 4
At 0, it is detected that the intake air is in a low temperature state. E
Based on the temperature information of the intake air from the intake air temperature sensor 40, the CU 41 raises the intake air temperature in order to raise the intake air temperature.
4 is instructed to adjust the opening.

In this state, as shown in FIG. 1, the recirculation passage 32 on the downstream side of the metering valve 34 is controlled by the metering valve 34.
Is communicated with only the heat-retaining passage 35 and only the high-temperature exhaust gas discharged from the combustion chamber 14 is kept warm.
To reflux. As a result, the temperature of the intake air supplied to the turbocharger 23 is increased and the compressor housing 2
Adiabatic compression in 7 further raises the temperature of the intake air supplied to the combustion chamber 14. By supplying the intake air whose temperature has been raised to the inside of the combustion chamber 14 while bypassing the intercooler 28, the warm-up of the internal combustion engine 11 is promoted and the combustion heat accompanying the combustion of the fuel in the combustion chamber 14 is promoted. This further raises the temperature of the exhaust gas.

In the state in which the recirculated exhaust gas passes through only the heat retention passage 35 in the heat exchanger 33 and is recirculated into the intake passage 16, the metering valve 34 closes the exhaust gas outlet in the cooling passage 36. As a result, exhaust gas is accumulated in the cooling passage 36 on the outer peripheral side of the heat retention passage 35,
The exhaust gas in the heat retention passage 35 is air-insulated to the low temperature outside air further outside the cooling passage 36 via the exhaust gas in the cooling passage 36. Therefore, the heat insulating passage 35
The exhaust gas inside is effectively kept warm.

The particulates contained in the exhaust gas discharged from the combustion chamber 14 are removed when passing through the DPF 21. Then, a part of the exhaust gas from which the particulates have been removed is recirculated to the intake passage 16 via the EGR device 31. On the other hand, the other part of the exhaust gas is N
After the amount of nitrogen oxides is reduced by the Ox storage catalyst 22, it is led to a muffler and eventually released to the atmosphere.

Here, the ECU 41 causes the high temperature exhaust gas passing through the heat retention passage 35 until the temperature of the exhaust gas discharged from the combustion chamber 14 to the metering valve 34 reaches the activation temperature of the NOx storage catalyst 22. Instruct to recirculate only the air into the intake passage 16. When the ECU 41 determines that the internal combustion engine 11 has been sufficiently warmed up and the temperature of the exhaust gas has reached the activation temperature of the NOx storage catalyst 22, the combustion chamber 1
In order to realize the condition that the exhaust gas from No. 4 maintains the activation temperature of the NOx storage catalyst 22, the metering valve 34 is instructed to adjust the opening. As a result, as shown in FIG. 2A, the metering valve 34 allows both the heat retention passage 35 and the cooling passage 36 to communicate with the intake passage 16 from the state where only the heat retention passage 35 communicates with the intake passage 16. The opening is adjusted so that

By adjusting the opening degree of the metering valve 34, the cooling passage 3 is protected against the high-temperature exhaust gas passing through the heat retaining passage 35.
The low-temperature exhaust gas passing through 6 is mixed, and the temperature of the recirculated exhaust gas recirculated to the intake passage 16 is lowered. Then, as the opening degree of the metering valve 34 is increased toward the heat retention passage 35 side, the proportion of high-temperature exhaust gas in the recirculation exhaust gas to the intake passage 16 increases, and the temperature of the recirculation exhaust gas rises. On the other hand, as the opening degree of the metering valve 34 is increased toward the cooling passage 36, the proportion of low-temperature exhaust gas in the recirculation exhaust gas to the intake passage 16 increases, and the temperature of the recirculation exhaust gas decreases.

Here, for example, when the outside temperature is high, the internal combustion engine 1
When the internal combustion engine 11 is sufficiently warmed up and the internal combustion engine 11 is operating in the high load region, the temperature of the exhaust gas tends to be high. In this state, if a part of the hot exhaust gas is recirculated to the intake passage 16 as it is, the temperature of the intake air becomes too high, which may affect the durability of the compressor wheel 26. Further, if the intake air temperature becomes too high, the charging efficiency in the internal combustion engine 11 is likely to decrease. In such a case, the ECU 41 determines that the metering valve 34
2B, only the low-temperature exhaust gas passing through the cooling passage 36 is recirculated to the intake passage 16 by adjusting the opening degree. When only this low-temperature recirculation exhaust gas is recirculated into the intake passage 16, the temperature of the recirculation exhaust gas becomes the lowest.

Here, on the outer peripheral surface of the cooling passage 36, a large number of heat radiation plates 39 bulging toward the outside air are provided. For this reason, the heat of the exhaust gas in the cooling passage 36 is efficiently transmitted to the outside air via the heat dissipation plate 39, and is effectively cooled.

Then, the ECU 41 uses the intake air temperature sensor 40.
The mixing ratio of the high temperature exhaust gas and the low temperature exhaust gas is changed by adjusting the opening degree of the metering valve 34 according to the temperature information of the intake air from the engine, the operating state of the internal combustion engine 11, and the like. The temperature of the recirculated exhaust gas recirculated to is adjusted.

Further, the internal combustion engine 11 is equipped with the DPF 21 and the NOx storage catalyst 22 as described above.
When the internal combustion engine 11 is operated for a long time, the DPF 21 is likely to be clogged with particulates contained in the exhaust gas discharged from the combustion chamber 14. Therefore, it is necessary to regenerate the DPF 21 by exposing the DPF 21 to high-temperature exhaust gas and burning the trapped particulates every predetermined time.

Further, in the NOx storage catalyst 22, when the internal combustion engine 11 is operated for a long time, the sulfur oxides contained in the exhaust gas discharged from the combustion chamber 14 are adsorbed and the ability to purify nitrogen oxides deteriorates. The poisoning phenomenon occurs. The NOx storage catalyst 22 also needs to be regenerated by exposing it to high-temperature exhaust gas every predetermined time to desorb and decompose the adsorbed sulfur oxides.

However, when the internal combustion engine 11 is operated in the low load region at the time when the regeneration of the DPF 21 and the NOx storage catalyst 22 is required, the temperature of the exhaust gas becomes DP.
There is a possibility that the temperature has not risen sufficiently to regenerate the F21 and NOx storage catalyst 22. In such cases, the ECU
Reference numeral 41 adjusts the opening of the metering valve 34 so that only the heat-retaining passage 35 communicates with the intake passage 16 so that only high-temperature exhaust gas is returned to the intake passage 16. And the air intake 1
The turbocharger 23 supercharges the intake air consisting of the intake air from 8 and the high-temperature recirculation exhaust gas, and bypasses the intercooler 28 if necessary, so that the combustion chamber 1
4 to supply. As a result, the high temperature intake air is transferred to the combustion chamber 1
Even if the internal combustion engine 11 is operated in the low load region while being supplied to the internal combustion engine 4, the temperature of the exhaust gas discharged from the combustion chamber 14 is increased, and the DPF 21 and the NOx storage catalyst 22 can be regenerated.

Then, the DPF 21 and the NOx storage catalyst 2
2 is exposed to the hot exhaust gas for a predetermined time, the ECU 4
No. 1 determines that the regeneration of the DPF 21 and the NOx storage catalyst 22 has been completed, and the internal combustion engine 1 at that time
Instructing the adjustment to the opening degree according to the operating state of No. 1. As a result, the mixing ratio of the high temperature exhaust gas and the low temperature exhaust gas is changed, and the temperature of the recirculated exhaust gas is adjusted. And
The temperature of the intake air formed from the intake air from the air intake 18 and the recirculated exhaust gas is adjusted. Further, the ECU 41 causes the intercooler 28 to cancel the bypass function in order to prevent the charging efficiency of the internal combustion engine 11 from decreasing, and restarts the cooling of the intake air.

By the way, it has been widely adopted from the past,
In the EGR device that recirculates a part of the exhaust gas from the exhaust passage on the upstream side of the turbine housing to the intake passage on the downstream side of the compressor housing, the intake air amount is shown by the one-dot chain line in FIG. This is the transition. That is, in an internal combustion engine that exhausts exhaust gas in front of the turbine wheel, the intake air amount tends to be insufficient in the partial high load region where the fuel injection amount increases and the high load region. This is because a part of the exhaust gas is recirculated to the EGR device side upstream of the turbine housing, so that the pressure of the exhaust gas is reduced and the rotational force applied to the turbine wheel is reduced.
Therefore, as indicated by the alternate long and short dash line in FIG. 3B, it is difficult to obtain sufficient supercharging pressure to completely burn the fuel in the combustion chamber from the partial high load region to the high load region, and the intake passage It was necessary to increase the amount of intake air from the outside air into the combustion chamber by reducing the amount of exhaust gas recirculation to the combustion chamber. Then, with the reduction of the exhaust gas recirculation amount, the temperature at which the fuel burns in the combustion chamber becomes excessively high, and the amount of generated nitrogen oxides tends to increase.

On the other hand, the internal combustion engine 11 of this embodiment is
Then, the EGR device 31 recirculates a part of the exhaust gas in the exhaust passage 17 downstream of the turbine housing 25 into the intake passage 16 upstream of the compressor housing 27. Therefore, the exhaust gas discharged from the combustion chamber 14 is guided to the turbine housing 25 of the turbocharger 23 while maintaining its exhaust pressure. That is, in the internal combustion engine 11, the decrease in the pressure of the exhaust gas before reaching the turbine wheel 24 is suppressed, and the turbine wheel 24 is efficiently rotated.

Therefore, in the internal combustion engine 11, the reduction of the supercharging pressure to the combustion chamber 14 due to the recirculation of a part of the exhaust gas into the intake passage 16 is suppressed. Then, regardless of the operating state of the internal combustion engine 11, a predetermined rotational force can be applied to the turbine wheel 24, and a predetermined supercharging pressure can be generated from the low load region to the high load region. Therefore, it is possible to generate a predetermined supercharging pressure from the partial high load region to the high load region where particulates are likely to occur due to insufficient intake air. Then, in this internal combustion engine 11, as shown by the solid line in FIG. 3A, compared with the internal combustion engine in which a part of the exhaust gas is recirculated from the upstream of the turbine housing, the intake air amount is increased in all load regions. Can be increased. As a result, even when the internal combustion engine 11 is operated in the partial high load range to the high load range, the air can be sufficiently supplied from the air intake port 18 into the combustion chamber 14, and the generation of particulates can be prevented. Suppressed.

Further, since the generation of particulates is suppressed from the partial high load region to the high load region, the recirculation amount of the recirculated exhaust gas into the intake passage 16 as shown by the solid line in FIG. 3 (b). Need not be reduced.
As a result, in this internal combustion engine 11, the combustion temperature in the combustion chamber 14 is prevented from rising excessively due to the effect of carbon dioxide in the recirculated exhaust gas, and the nitrogen oxides in the partial high load region to the high load region are suppressed. Is reduced.

Furthermore, in this internal combustion engine 11, although a part of the exhaust gas is recirculated into the intake passage 16 via the EGR device 31, the rotation speed of the turbine wheel 24 becomes the exhaust pressure from the combustion chamber 14. Can be kept high accordingly. For this reason, for example, when you are going uphill,
When the driver makes an acceleration request, the internal combustion engine 11
Even when a sudden load increase request occurs, the supercharging pressure can be quickly increased. Therefore, the transient response delay to the sudden load demand on the internal combustion engine 11 is reduced.
Further, the occurrence of transient air shortage is suppressed, and the fuel injection valve 15
The fuel injection amount from the internal combustion engine 11 can be increased.
The transient acceleration performance of is improved.

As described in detail above, according to the EGR device 31, the heat exchanger 33 and the internal combustion engine 11 according to this embodiment, the following excellent effects can be obtained. (1) In this EGR device 31, a heat retention passage 35 that allows the recirculation exhaust gas to pass while keeping it warm, a cooling passage 36 that allows the recirculation exhaust gas to pass while cooling, and a high-temperature recirculation exhaust gas that has passed through the heat retention passage 35 and cooling. The low temperature recirculated exhaust gas that has passed through the passage 36 is provided individually or in a mixture, and is guided to the intake passage 16. The metering valve 34 adjusts the mixing ratio of the high-temperature recirculation exhaust gas and the low-temperature recirculation exhaust gas according to the temperature information of the intake air supplied to the internal combustion engine 11, and guides it to the intake passage 16. ing.

Therefore, for example, when the internal combustion engine 11 is cold started, warming-up of the internal combustion engine 11 can be promoted by circulating only the high-temperature recirculated exhaust gas into the intake passage 16, and the temperature of the exhaust gas can be increased. Can be raised quickly. On the other hand, for example, when the internal combustion engine 11 is sufficiently warmed up and the internal combustion engine 11 is operating in the high load region, the proportion of the low-temperature recirculated exhaust gas is increased and recirculated to the intake passage 16. Therefore, the internal combustion engine 11
It is possible to suppress a decrease in the filling efficiency.

As described above, the intake valve is adjusted to the required temperature state by adjusting the mixing ratio of the high-temperature recirculation exhaust gas and the low-temperature recirculation exhaust gas by the metering valve 34 according to the temperature state of the intake air. It becomes possible to do. Then, by adjusting the temperature of the intake air, the operating state of the internal combustion engine 11, the warm-up state, the surrounding environment, the DPF 21 and the NOx storage catalyst 22.
The temperature of the exhaust gas can be controlled more appropriately in order to meet the above-mentioned regeneration request.

(2) In this EGR device 31, the metering valve 3
4 adjusts the mixing ratio of the high-temperature recirculation exhaust gas and the low-temperature recirculation exhaust gas in accordance with the temperature information of the intake air in the intake passage 16 on the upstream side of the turbocharger 23. Therefore, it is possible to control the temperature of the intake air supplied to the turbocharger 23, and when the high-temperature intake air is supplied, the temperature of the intake air is controlled by the compressor housing 27.
It is possible to suppress an unexpected rise due to adiabatic compression in the interior and affecting the compressor wheel 26 and the like.

(3) In the EGR device 31, the exhaust gas passing through the DPF 21 for removing particulates is supplied to the recirculation passage 32. Therefore, E
GR device 31, turbocharger 23 and internal combustion engine 11
Adhesion of deposits derived from the particulates discharged from the combustion chamber 14 is suppressed on the surface of each component of the above. Therefore, the EGR device 31, the turbocharger 2
3 and the durability of the internal combustion engine 11 can be improved.

(4) In this EGR device 31, the heat exchanger 33 has a double pipe structure in which the heat insulating passage 35 is arranged on the center side and the cooling passage 36 is provided so as to cover the outer peripheral surface of the heat insulating passage 35. Is doing. Therefore, the cooling passage 36
The exhaust gas in the heat retention passage 35 can be thermally insulated from the outside air by the exhaust gas in the cooling passage 36 while the outer peripheral surface of the is in contact with the outside air. The exhaust gas in the cooling passage 36 can be efficiently cooled, and the exhaust gas in the heat retaining passage 35 can be effectively kept warm. Further, the heat exchanger 33 including the heat retaining passage 35 and the cooling passage 36 can be configured in a simple and compact manner.

(5) The EGR device 31 has the heat radiating plate 39 which bulges into the outside air from the outer peripheral surface of the cooling passage 36. Therefore, the exhaust gas in the cooling passage 36 can be efficiently cooled with a very simple configuration.

(6) In this EGR device 31, the heat insulating passage 35 is provided in the partition wall 37 between the heat insulating passage 35 and the cooling passage 36.
A heat insulating material 38 that suppresses heat transfer between the exhaust gas inside and the exhaust gas inside the cooling passage 36 is provided. For this reason,
Heat transfer between the exhaust gas in the heat retention passage 35 and the exhaust gas in the cooling passage 36 is suppressed, and both the heat retention of the exhaust gas in the heat retention passage 35 and the cooling efficiency of the exhaust gas in the cooling passage 36 are improved. Can be made.

(7) In this EGR device 31, the metering valve 3
When supplying the exhaust gas in the heat retention passage 35 exclusively to the intake passage 16, the exhaust gas outlet 4 closes the outlet of the exhaust gas in the cooling passage 36 to retain the exhaust gas in the cooling passage 36. . Therefore, the heat insulating passage 3 is provided due to the air heat insulating effect due to the presence of the exhaust gas staying in the cooling passage 36.
The heat retaining effect of the exhaust gas in 5 can be further enhanced.

(8) In the internal combustion engine 11, the EGR device 31 recirculates the recirculated exhaust gas from the exhaust passage 17 on the downstream side of the turbocharger 23 to the intake passage 16 on the upstream side of the turbocharger 23. . For this reason,
The introduction of the recirculated exhaust gas into the EGR device 31 does not reduce the exhaust pressure applied to the turbine wheel 24. Then, regardless of the operating state of the internal combustion engine 11, a predetermined rotational force can be applied to the turbine wheel 24, and a predetermined supercharging pressure can be generated from the low load region to the high load region. As a result, even in the partial high load region to the high load region, sufficient air is sucked into the combustion chamber 14 and the generation of particulates can be suppressed. Then, it becomes possible to increase the recirculation amount of the exhaust gas, and it is possible to reduce the amount of nitrogen oxides discharged from the combustion chamber 14.

Further, the rotational speed of the turbine wheel 24 in the turbocharger 23 can be kept high in accordance with the exhaust pressure of the exhaust gas discharged from the combustion chamber 14. Therefore, when there is a sudden load increase request to the internal combustion engine 11, the supercharging pressure can be raised rapidly, and the transient response delay to the load request can be reduced. Then, the occurrence of transient air shortage is suppressed, the fuel injection amount can be increased, and the transient acceleration performance can be improved.

(9) In this internal combustion engine 11, the above (1)
The EGR device 31 according to (8) is provided. Therefore, the temperature of the intake air is adjusted as necessary to improve the warm-up performance of the internal combustion engine 11, the early activation of the exhaust gas purification catalyst, the DPF 21 and the NOx storage without complicating the configuration of the internal combustion engine 11. The regeneration performance of the catalyst 22 can be improved.

(10) The internal combustion engine 11 is equipped with an EGR device 31 for adjusting the temperature of intake air and a turbocharger 23 having a compressor wheel 26 made of aluminum alloy. Therefore, the turbocharger 2
It is possible to prevent the intake air supplied to the compressor 3 from being raised above the heat resistant temperature of the compressor wheel 26 due to adiabatic compression in the compressor housing 27. Therefore, the EGR device 31 and the heat exchanger 33 of the present embodiment are particularly suitable for the internal combustion engine 11 including the turbocharger 23 having the compressor wheel 26 made of an aluminum alloy whose usage conditions are severe at high temperatures.

(11) In the internal combustion engine 11, the combustion chamber 1
4 has a fuel injection valve 15 for directly injecting fuel. In the internal combustion engine 11 that directly injects fuel into the combustion chamber 14 as described above, the amounts of nitrogen oxides, sulfur oxides, and particulates generated increase. Therefore, E of the present embodiment
The GR device 31 and the heat exchanger 33 are particularly effective for such a direct injection type internal combustion engine.

(12) In this internal combustion engine 11, an intake throttle valve 20 for restricting intake air passing through the intake passage 16 is provided in the intake passage 16. Therefore, the internal combustion engine 11
Of the intake throttle valve 20 when the operating state of the engine is in the low load region.
As a result, the amount of intake air taken in from the air intake 18 can be reduced, and more high-temperature recirculation exhaust gas can be recirculated to the intake passage 16. As a result, the temperature of the exhaust gas discharged from the combustion chamber 14 can be raised more quickly.

(Modification) The above embodiment can be modified as follows, for example. In the EGR device 31 of the above-described embodiment, the intake temperature sensor 40 in which the metering valve 34 is arranged upstream of the turbocharger 23
The opening degree of the metering valve 34 is adjusted based on the temperature information of the intake air.

On the other hand, in the ECU 41, based on the intake air temperature information from the downstream intake air temperature sensor 44 (see FIG. 1) arranged in the intake passage 16 on the downstream side of the turbocharger 23, the turbocharger 23 Estimate the temperature of the intake air upstream. Then, the opening degree of the metering valve 34 is adjusted according to the estimated intake air temperature upstream of the turbocharger 23 to adjust the mixing ratio of the high-temperature recirculation exhaust gas and the low-temperature recirculation exhaust gas. May be.

Even with this structure, the temperature of the intake air supplied to the turbocharger 23 can be controlled, and when the high-temperature intake air is supplied, the temperature of the intake air is adiabatic in the compressor housing 27. It is possible to suppress an unexpected rise due to compression and affecting the compressor wheel 26 and the like.

Further, as shown in FIG. 1, for example, an intake air temperature sensor 45 may be arranged in the intake passage 16 on the downstream side of the air cleaner 19. Further, the cooling water temperature sensor 46 may be arranged in the cylinder 12. In addition, D to DPF21
The PF temperature sensor 47 and the catalyst bed temperature sensor 48 may be provided in the NOx storage catalyst 22. Then, in the ECU 41, at least one of the temperature information from these various sensors is
The opening of the metering valve 34 may be determined in consideration of the above.

In the turbocharger 23 of the above embodiment, the compressor wheel 26 made of aluminum alloy is adopted, but the compressor wheel 26 made of ceramics may be adopted.

According to this structure, the heat resistance of the compressor wheel 26 can be improved, and a higher temperature intake air can be supplied to the turbocharger 23. Therefore, the amount of high-temperature exhaust gas recirculated to the intake passage 16 can be increased, and the warm-up performance of the internal combustion engine 11 can be improved. Further, when the internal combustion engine 11 is operating in the low load region, the DPF 21 and the NOx storage catalyst 22 can be rapidly shifted to the reproducible state.

In the heat exchanger 33 of the above embodiment,
The heat dissipation plate 39 on the outer peripheral surface of the cooling passage 36 may be omitted. In the heat exchanger 33 of the above-described embodiment, the heat dissipation plate 39 is expanded from the outer peripheral surface of the cooling passage 36, and the heat dissipation plate 39 is brought into contact with the outside air to cool the exhaust gas in the cooling passage 36. I have to. On the other hand, the cooling passage 3
For example, a water jacket may be provided on the outer peripheral surface of 6, and the outer peripheral surface of the cooling passage 36 may be brought into contact with cooling water or the like to cool the exhaust gas in the cooling passage 36.

In the heat exchanger 33 of the above embodiment, the heat insulating material 3 inside the partition wall 37 between the heat retaining passage 35 and the cooling passage 36 is used.
Although a ceramics tube is adopted as 8, a porous cylindrical body made of metal such as honeycomb or sponge may be adopted. Further, the heat insulating material 38 may be omitted.

In the heat exchanger 33 of the above embodiment, the cooling passage 36 is formed so as to cover the outer peripheral surface of the heat retaining passage 35 over the entire length of the heat retaining passage 35. However, the cooling passage 36 keeps the outer peripheral surface of the heat retaining passage 35 warm. It may be formed so as to cover a part of the passage 35 in the longitudinal direction. In this case, a portion of the outer peripheral surface of the heat retaining passage 35 which is not covered with the cooling passage 36 is
It is preferable to provide a heat insulating material in order to enhance the heat retention of the exhaust gas inside.

In the heat exchanger 33 of the above embodiment, the heat retaining passage 35 and the cooling passage 36 are formed to have a double pipe structure. On the other hand, the heat-retaining passage 35 and the cooling passage 36 are formed independently of each other, and both passages 35, 3 are formed.
6 may be joined before the metering valve 34, and the metering valve 34 may adjust the mixing ratio of the high-temperature recirculation exhaust gas and the low-temperature recirculation exhaust gas. In this case, it is preferable to provide a heat insulating material on the outer peripheral surface of the heat retaining passage 35 in order to enhance the heat retaining property of the exhaust gas inside.

In the above embodiment, the present invention is embodied in the internal combustion engine 11 composed of a diesel engine, but the present invention may be embodied in an internal combustion engine composed of, for example, a fuel cylinder direct injection type gasoline engine.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment in which the present invention is embodied in a diesel engine and an EGR device thereof.

FIG. 2 (a) is an explanatory view showing a state in which (a) in the metering valve is mixed with high-temperature exhaust gas and low-temperature exhaust gas and recirculated.
(B) is an explanatory view showing a state in which only low-temperature exhaust gas is recirculated.

3A is an explanatory diagram showing a relationship between a load state of the internal combustion engine and an intake air amount, and FIG. 3B is an explanatory diagram showing a relationship between a load state of the internal combustion engine and a recirculated exhaust gas amount.

[Explanation of symbols]

11 ... Internal combustion engine, 14 ... Combustion chamber, 15 ... Fuel injection valve as fuel injection device, 16 ... Intake passage, 17 ... Exhaust passage,
20 ... Intake throttle valve, 21 ... Diesel particulate filter (DPF) as a contained component reducing device, 2
3 ... Turbocharger as supercharger, 26 ... Compressor wheel, 31 ... Exhaust gas recirculation device (EGR device),
32 ... Recirculation passage as exhaust gas recirculation passage, 33 ... Heat exchanger, 34 ... Metering valve as regulator, 35 ... Insulation passage, 3
6 ... Cooling passage, 37 ... Partition wall, 38 ... Heat insulating material as heat insulating means, 39 ... Radiating plate.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 25/07 F02M 25/07 580B 580D F02B 37/00 302 F02B 37/00 302F 39/00 39/00 U F02D 9 / 02 F02D 9/02 A CS 21/08 301 21/08 301C 311 311B F term (reference) 3G005 EA16 FA35 GA02 GB15 GB26 HA12 HA18 JA13 JA16 3G062 AA01 AA05 CA01 CA02 CA07 CA08 ED01 ED04 GA08 FA12 GA12 FA12 GA12 3G065 AA00 AA03 CA12 DA04 GA09 GA27 3G092 AA01 AA02 AA06 AA17 AA18 DB03 DC01 DC08 DE03S EA11 EA28 EA29 FA17 FA20 GA01 GA02 GA04 GA05 GA06 HA04Z HD02Z HE08Z

Claims (19)

[Claims] 1. An exhaust gas recirculation passage that recirculates a part of exhaust gas discharged from a combustion chamber of an internal combustion engine into an intake passage through which intake air supplied to the combustion chamber passes, and is recirculated into the intake passage. An exhaust gas recirculation device for adjusting the temperature of the recirculated exhaust gas, wherein the temperature controller has a heat-retaining passage for passing at least a part of the recirculated exhaust gas while keeping the heat, and the recirculated exhaust gas. A cooling passage for passing at least a part of the gas while cooling,
An adjuster for guiding the recirculated exhaust gas that has passed through the heat retention passage and the recirculated exhaust gas that has passed through the cooling passage to the intake passage, either individually or in combination, is provided for the intake air supplied to the internal combustion engine. Depending on the temperature information of the above, it is possible to adjust the mixing ratio of the high-temperature recirculation exhaust gas that has passed through the heat retention passage and the low-temperature recirculation exhaust gas that has passed through the cooling passage to guide the recirculation exhaust gas to the intake passage. Characteristic exhaust gas recirculation device. 2. The high-temperature regulator which has passed through the heat retaining passage according to temperature information of a mixed gas in an intake passage upstream of a supercharger for supercharging intake air supplied to the combustion chamber. The exhaust gas recirculation device according to claim 1, wherein a mixing ratio of the reflux exhaust gas and the low-temperature reflux exhaust gas that has passed through the cooling passage is adjusted. 3. The upstream side of the supercharger estimated based on temperature information of the mixed gas in the intake passage on the downstream side of the supercharger for supercharging the intake air supplied to the combustion chamber. 2. The mixing ratio of the high-temperature recirculation exhaust gas that has passed through the heat retaining passage and the low-temperature recirculation exhaust gas that has passed through the cooling passage is adjusted according to the temperature information of the mixed gas. Exhaust gas recirculation equipment. 4. The exhaust gas supplied to the exhaust gas recirculation passage is exhaust gas that has passed through a contained component reducing device that reduces the amount of particulates contained in the state of being discharged from the combustion chamber. The exhaust gas recirculation device according to any one of claims 1 to 3. 5. The heat retaining passage and the cooling passage are formed in a heat exchanger having a double pipe structure, the heat retaining passage is arranged on the center side, and at least a part of an outer peripheral surface of the heat retaining passage is formed. The exhaust gas recirculation device according to any one of claims 1 to 4, wherein the cooling passage is provided so as to cover the exhaust gas recirculation device. 6. The exhaust gas recirculation device according to claim 5, wherein a heat radiating means for radiating the heat of the exhaust gas in the cooling passage to the outside is provided on the outer peripheral surface of the cooling passage. 7. The exhaust gas recirculation device according to claim 6, wherein the heat radiating means comprises a heat radiating plate bulging into the outside air from the outer surface of the cooling passage. 8. A heat insulating means for suppressing heat transfer between exhaust gas in the heat retaining passage and exhaust gas in the cooling passage is provided on a partition wall between the heat retaining passage and the cooling passage. The exhaust gas recirculation device according to any one of claims 5 to 7. 9. When the exhaust gas in the heat retaining passage is exclusively supplied to the intake passage, the regulator closes the outlet of the exhaust gas in the cooling passage to keep the exhaust gas in the cooling passage. The exhaust gas recirculation device according to claim 5, wherein the exhaust gas recirculation device is retained. 10. The recirculation exhaust gas is recirculated from an exhaust passage downstream of a supercharger that supercharges intake air supplied into the combustion chamber to an intake passage upstream of the supercharger. The exhaust gas recirculation device according to any one of claims 1 to 9. 11. An exhaust gas recirculation passage of an exhaust gas recirculation device for recirculating a part of exhaust gas discharged from a combustion chamber of an internal combustion engine into an intake passage through which intake air supplied to the combustion chamber passes. A heat exchanger that keeps at least a portion of the recirculated exhaust gas recirculated in the intake passage while keeping a temperature, and a cooling passage that allows at least a portion of the recirculated exhaust gas to pass while being cooled. The exhaust gas recirculation is characterized in that the heat-retaining passage is arranged on the center side, and the cooling passage is formed so as to form a double pipe structure provided so as to cover at least a part of the outer peripheral surface of the heat-retaining passage. A heat exchanger used in the equipment. 12. The exhaust gas recirculation apparatus according to claim 11, wherein a heat radiating means for radiating the heat of the exhaust gas in the cooling passage to the outside is provided on the outer peripheral surface of the cooling passage. The heat exchanger used. 13. The heat exchanger used in the exhaust gas recirculation apparatus according to claim 12, wherein the heat radiating means comprises a heat radiating plate that bulges into the outside air from the outer surface of the cooling passage. 14. A partition between the heat retaining passage and the cooling passage is provided with heat insulating means for suppressing heat transfer between the exhaust gas in the heat retaining passage and the exhaust gas in the cooling passage. A heat exchanger used in the exhaust gas recirculation device according to any one of claims 11 to 13. 15. An internal combustion engine having an exhaust gas recirculation device for returning a part of exhaust gas discharged from a combustion chamber into an intake passage, wherein the exhaust gas recirculation device according to any one of claims 1 to 10. An internal combustion engine having a circulation device. 16. A compressor wheel comprising a supercharger for supercharging the intake air supplied to the combustion chamber, wherein the compressor wheel arranged in the supercharger for increasing the pressure of the intake air is made of aluminum or an aluminum alloy. Claim 1 characterized by
The internal combustion engine according to item 5. 17. A supercharger for supercharging the intake air supplied to the combustion chamber, wherein a compressor wheel arranged in the supercharger for increasing the pressure of the intake air is made of ceramics. The internal combustion engine according to claim 15. 18. The internal combustion engine according to claim 15, further comprising a fuel injection device that directly injects fuel into the combustion chamber. 19. The internal combustion engine according to claim 18, wherein an intake throttle valve for restricting intake air passing through the intake passage is provided in the intake passage.