JP2001342911A - Exhaust gas re-circulation control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an efficiency of turbo-charger in a wide engine revolution number area by carrying out a reflux of exhaust gas in the case where a pressure of suction circuit is higher than that of exhaust circuit in an internal combustion engine. SOLUTION: A first heat exchanger 15a for carrying out a heat exchange between a feed/exhaust by-path circuit 20 communicating a suction circuit 12 with an exhaust circuit 16 and an exhaust gas re-circulation circuit 15 is provided. In addition thereto, a second heat exchanger 15b for cooling a re- circulation exhaust gas with a cooling water is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust gas recirculation control device for an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental protection, regulations on harmful substances emitted from an internal combustion engine have been strengthened in various places.
Exhaust gas recirculation (commonly known as EGR) is widely known and used as a method of reducing harmful substances contained in exhaust gas of an internal combustion engine. A part of the exhaust gas discharged from the combustion chamber is recirculated from the exhaust manifold to the intake manifold, mixed with the intake air, and sent back to the combustion chamber, thereby reducing the oxygen concentration in the intake air and lowering the combustion temperature. The effect of suppressing the generation of harmful substances, particularly nitrogen oxides (hereinafter abbreviated as NO _X ), contained in water is large.

FIG. 3 shows a conventional configuration as disclosed in
FIG. 1 shows a supply / exhaust circuit diagram of a turbocharged engine 14 having an exhaust gas recirculation device described in Japanese Patent No. 81017. The engine 14 includes a turbocharger 11, an intake circuit 12, an aftercooler 13, and an exhaust recirculation circuit 1.
5 and an exhaust circuit 16. Turbocharger 1
The intake air compressed by the compressor 11a is an intake circuit 1
After passing through 2, the air is cooled by an aftercooler 13 provided on the way, and is introduced into the engine body 14a via the intake manifold 12a. The exhaust gas discharged from the engine body 14a flows into the turbocharger 11 through the exhaust circuit 16, and is driven and discharged by the turbine 11b. Between the downstream side of the aftercooler 13 of the intake circuit 12 and the vicinity of the inlet of the turbine 11b of the exhaust circuit 16, there is provided a supply / exhaust bypass circuit 20 for communicating these components. Exhaust bypass valve 20a
Is provided. One end of the exhaust gas recirculation circuit 15 is branched and connected near the exhaust manifold 16a of the exhaust circuit 16,
The other end is branched and connected to the intake circuit 12 near the intake manifold 12a. In the exhaust gas recirculation circuit 15, an EGR valve 15c for opening and closing the exhaust gas recirculation circuit 15 and a heat exchanger 15d for exchanging heat between the exhaust gas recirculation circuit 15 and the supply / exhaust bypass circuit 20 are provided. Have been.

[0004] By cooling the exhaust gas reflux, while suppressing the generation of drops combustion temperature NO _X, the exhaust circuit 16
By heating and expanding the intake air that joins the exhaust gas, the loss of exhaust gas due to the recirculation can be compensated for, and the rotation speed of the turbocharger 11 can be maintained.

[0005]

However, the above embodiment has the following problems. When the engine 14 is operated under a certain condition, for example, at a medium / high speed / high load, the intake manifold 12
a becomes higher than the pressure of the exhaust manifold 16a (this is because the characteristics of the turbocharger generally match the frequently-used operating conditions, thereby improving the efficiency of the engine and obtaining high output and low fuel consumption). The higher the pressure on the intake side and the lower the pressure on the exhaust side, the smaller the supply / exhaust resistance that causes a loss in output). Therefore, a part of the intake air pressurized by the compressor 11a flows to the exhaust circuit 16 via the supply / exhaust bypass circuit 20, and heat exchange with the exhaust gas can be performed. However, the intake manifold 12
Under operating conditions such as when the pressure of a is lower than the pressure of the exhaust manifold 16a, for example, during low speed and low load operation, the above-described flow in the supply / exhaust bypass circuit 20 does not occur. Therefore, the operating conditions under which the recirculated exhaust gas can be cooled by operating the heat exchanger 15d are limited.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an exhaust gas recirculation control device for an internal combustion engine that can cool recirculated exhaust gas under a wide range of operating conditions. .

[0007]

In order to achieve the above object, the present invention provides a turbocharger having a compressor disposed on an intake circuit and a turbine disposed on an exhaust circuit, and an exhaust circuit. An exhaust recirculation circuit that connects between the turbine and the internal combustion engine main body and between the compressor and the internal combustion engine main body of the intake circuit and can be opened and closed by a first on-off valve; A first heat exchange for providing heat exchange between an exhaust gas recirculation circuit and a supply / exhaust bypass circuit while providing a supply / exhaust bypass circuit which connects the compressor and the internal combustion engine body and can be freely opened / closed by a second opening / closing valve; An exhaust gas recirculation control device for an internal combustion engine having a heat exchanger, wherein a second heat exchanger that cools the recirculated exhaust gas in the exhaust gas recirculation circuit using water as a refrigerant is located downstream of the first heat exchanger. Characterized by providing a position of the exhaust gas recirculation circuit that.

In particular, an aftercooler for cooling the intake air is provided between the compressor and the main body of the internal combustion engine.
It is desirable that the connection position of the supply / exhaust bypass circuit to the intake circuit be between the compressor and the aftercooler.

Further, a throttle having a narrow portion for narrowing the flow of intake air between the compressor and the internal combustion engine main body is provided in the intake circuit, and a connection position of the exhaust gas recirculation circuit is substantially at the center of the narrow portion.
A bypass connection may be provided between the upstream and the downstream of the throttle by bypass connection and opened and closed by a third on-off valve, and the connection position of the air supply / exhaust bypass circuit with respect to the intake circuit may be between the compressor and the throttle.
A throttle valve for reducing the flow of intake air between the compressor and the internal combustion engine body is provided in the intake circuit, the connection position of the exhaust gas recirculation circuit is set between the throttle valve and the internal combustion engine body, and the connection position of the supply / exhaust bypass circuit to the intake circuit is the compressor. -It may be between throttle valves. Further, the second on-off valve may be a check valve that allows flow in only one direction from the compressor downstream of the turbocharger to the turbine upstream.

According to the above configuration of the present invention, the following effects can be obtained. (1) The recirculated exhaust gas is passed through both the first heat exchanger and the second heat exchanger arranged in series. Therefore,
Even in an operation state in which the pressure on the intake side is lower than the pressure on the exhaust side, no flow occurs in the supply / exhaust bypass circuit and the cooling effect of the first heat exchanger cannot be obtained, the water-cooled second heat exchanger is used. The recirculating exhaust gas can be cooled. Further, in an operating state in which the intake side pressure is higher than the exhaust side, a flow occurs in the supply / exhaust bypass circuit, and the cooling effect of the first heat exchanger is obtained, and the first heat exchanger and the second heat exchange Since the recirculated exhaust gas can be cooled by both the heat exchanger and the heat exchanger, the cooling capacity of the first heat exchanger can be reduced, that is, the outer dimensions can be reduced as compared with the case where the second heat exchanger is not provided. Usually, the first heat exchanger of the air-cooled type has a lower cooling efficiency than the second heat exchanger of the water-cooled type, and tends to be inevitably larger. However, according to the present invention, the load on the cooling capacity is reduced. By reducing the size, the contribution to the miniaturization of the entire apparatus also increases. Furthermore, the first heat exchanger is located upstream of the second heat exchanger and introduces high-temperature exhaust gas, so that the temperature difference between the recirculated exhaust gas and the bypassed intake air is widened, and the first heat exchanger is compared with the second heat exchanger. As a result, the cooling efficiency of the inferior first heat exchanger can be increased. Thus, the temperature of the intake air flowing into the exhaust circuit by bypass is further increased to expand the volume, and the rotational speed of the turbocharger is further increased, so that the heat energy of the recirculated exhaust gas can be more effectively used. At the same time, the temperature of the exhaust gas introduced into the second heat exchanger decreases,
The temperature rise of the cooling water in the second heat exchanger can be suppressed, and the supply flow rate of the cooling water and, if there is a radiator, the burden on the radiator can be minimized.

(2) By connecting the supply / exhaust bypass circuit to a position of the intake circuit upstream of the aftercooler,
The heat balance of the aftercooler can be improved. That is, the temperature of the intake air after passing through the aftercooler is reduced to reduce the flow rate of the intake air passing through the aftercooler by an amount corresponding to the bypass to the exhaust circuit. As a result, the combustion temperature is further reduced, and the generation of NO _X can be suppressed more remarkably.

(3) If a throttle having a narrow portion is provided and an exhaust recirculation circuit is connected substantially at the center of the narrow portion, the flow rate of intake air can be increased in the narrow portion of the intake circuit, and the pressure can be partially reduced. In addition, by adjusting the opening degree of the intake bypass valve, the flow rate of intake air passing through the narrow portion can be adjusted, and the narrow portion intake pressure can be freely adjusted. Also, if the throttle valve is provided in the intake circuit and the connection position of the exhaust recirculation circuit is between the throttle valve and the internal combustion engine body, the pressure at the position where the exhaust recirculation circuit is connected to the intake circuit is reduced by the resistance of the throttle valve. become able to. Therefore, in either of the two configurations, the exhaust gas recirculation device can be operated under a wide range of operating conditions from a low-speed / low-load region to a high-speed / high-load region to reduce harmful components in the exhaust gas. In addition, supply and exhaust bypass circuit
If the valve is opened and closed by a simple element called a check valve, the structure can be simplified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIG. The same components as the components described in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. In the turbocharged engine 14 having the exhaust gas recirculation device, the exhaust gas recirculation circuit 15 is connected to the intake circuit 12 before the intake circuit 12 on the upstream side of the intake manifold 12a. A supply / exhaust bypass circuit 20 is provided between the intake circuit 12 near the outlet of the compressor 11a and the exhaust circuit 16 near the inlet of the turbine 11b. An exhaust bypass valve 20a is provided. An aftercooler 13 for cooling the intake air is provided between a connection position of the supply / exhaust bypass circuit 20 on the upstream side of the intake circuit 12 and a connection position of the exhaust gas recirculation circuit 15 on the downstream side.
And a throttle valve 17 for freely reducing the cross-sectional area of the passage of the intake circuit 12
Are provided.

In the exhaust gas recirculation circuit 15, the exhaust gas recirculation circuit 15
Valve 15c for opening and closing the exhaust gas and the exhaust gas recirculation circuit 1
5 that performs heat exchange between the air supply 5 and the supply / exhaust bypass circuit 20
A heat exchanger 15a and a second heat exchanger 15b for cooling the exhaust gas in the exhaust gas recirculation circuit 15 with engine cooling water are provided. The engine cooling water supplied to the second heat exchanger 15b circulates while radiating heat by a radiator (not shown).

The engine 14 further includes a detecting means 31 for detecting an operating state of the engine 14, and a signal from the detecting means 31, and receives signals from the EGR valve 15c, the throttle valve 17, and the supply / exhaust bypass valve 20a. Controller 33 for controlling opening
And The control unit 33 controls the EGR valve 15c as necessary.
Is controlled to control the flow rate of the recirculated exhaust gas (hereinafter referred to as the EGR amount). However, when the pressure of the intake manifold 12a becomes higher than the pressure of the exhaust manifold 16a, the exhaust gas cannot be recirculated even if the EGR valve 15c is opened. Therefore, the pressure of the intake manifold 12a is changed to the exhaust manifold 1
The control unit 33 opens the supply / exhaust bypass valve 20a only when it is detected by the detection unit 31 that the pressure is higher than the pressure of 6a and when it is necessary to recirculate the exhaust gas. Then, part of the intake air pressurized by the compressor 11a flows to the exhaust circuit 16 via the supply / exhaust bypass circuit 20, and the intake manifold 1
The pressure at 2a decreases and the pressure at exhaust manifold 16a increases. As a result, the pressure of the intake manifold 12a can be made equal to or lower than the pressure of the exhaust manifold 16a, so that exhaust gas can be recirculated. At the same time, the control unit 33 reduces the opening of the throttle valve 17. Then, the resistance of the throttle valve 17 further lowers the pressure downstream of the throttle valve 17, that is, the pressure of the intake manifold 12a, so that the recirculation of exhaust gas becomes easier.

When the exhaust gas is recirculated under the condition that the pressure of the intake manifold 12a is higher than the pressure of the exhaust manifold 16a, the control unit 33 opens the EGR valve 15c and the supply / exhaust bypass valve 20a as described above. Then, a part of the exhaust gas branches off in the exhaust circuit 16 and flows to the exhaust gas recirculation circuit 15, where E
After being cooled by the first heat exchanger 15a and the second heat exchanger 15b via the GR valve 15c, it is mixed with intake air in the intake circuit 12 and introduced into the engine body 14a. At the same time, a part of the intake air pressurized by the compressor 11a flows to the supply / exhaust bypass circuit 20 at a position upstream of the connection position of the aftercooler 13 and the exhaust recirculation circuit 15, and passes through the supply / exhaust bypass valve 20a to the first heat exchanger 15a. After being heated, it is mixed with the exhaust gas in the exhaust circuit 16 and introduced into the turbine 11b. The pressure of the intake manifold 12a becomes higher than the pressure of the exhaust manifold 16a under operating conditions such as high load operation, and the temperature of the exhaust gas is often high. Therefore, by cooling the recirculated exhaust gas by both the first heat exchanger 15a and the second heat exchanger 15b, the temperature can be effectively lowered.

When the exhaust gas is recirculated under the condition that the pressure of the intake manifold 12a is equal to or less than the pressure of the exhaust manifold 16a, first, the control unit 33 opens the EGR valve 15c and closes the supply / exhaust bypass valve 20a. Then, a part of the exhaust gas branches in the exhaust circuit 16 and flows to the exhaust gas recirculation circuit 15,
After passing through the first heat exchanger 15a and the second heat exchanger 15b via the EGR valve 15c, the aftercooler 1 in the intake circuit 12
At a position downstream of 3, it is mixed with the intake air and introduced into the engine body 14a. At this time, since no flow occurs in the supply / exhaust bypass circuit 20, the recirculated exhaust gas cannot be cooled by the first heat exchanger 15a. The recirculated exhaust gas is the second heat exchanger 1
5b only cools the intake manifold 12
The cooling capacity is reduced as compared with the case where the exhaust gas is recirculated under the condition that the pressure of a becomes higher than the pressure of the exhaust manifold 16a. However, the pressure of the intake manifold 12a becomes equal to or lower than the pressure of the exhaust manifold 16a under operating conditions such as low-speed and low-load operation, and the temperature of the exhaust gas is often low. do not become.

According to the first embodiment, the recirculated exhaust gas is
First heat exchanger 15a and second heat exchanger 15b arranged in series
And through both. Therefore, since the pressure of the intake manifold 12a is lower than the pressure of the exhaust manifold 16a, no flow occurs in the supply / exhaust bypass circuit 20 and the first
Even in an operation state in which the cooling effect of the heat exchanger 15a cannot be obtained, the exhaust gas recirculated by the water-cooled second heat exchanger 15b can be cooled. Further, in an operation state in which the pressure of the intake manifold 12a is higher than the pressure of the exhaust manifold 16a, a flow occurs in the supply / exhaust bypass circuit 20 and the cooling effect of the first heat exchanger 15a is obtained, the first heat exchange Since the temperature of the exhaust gas recirculated in both the heat exchanger 15a and the second heat exchanger 15b can be effectively reduced, the load is reduced as compared with the case where the second heat exchanger 15b is not provided, and the first heat The cooling capacity of the exchanger 15a can be set small, that is, the external size can be set small. Usually, the air-cooled first heat exchanger 15a is inferior to the water-cooled second heat exchanger 15b in cooling efficiency and tends to be inevitably larger, but is reduced in size by reducing the load on the cooling capacity. As a result, the contribution to the miniaturization of the entire apparatus also increases. In addition, since the exhaust gas that has been cooled to some extent by the first air-cooled first heat exchanger 15a is introduced into the second water-cooled second heat exchanger 15b, the temperature rise of the engine coolant in the second heat exchanger 15b can be reduced. Minimizing the load on the radiator. At the same time, the first heat exchanger 15a
By introducing high-temperature exhaust gas first, the temperature difference between the recirculated exhaust gas and the bypass intake air increases, and the cooling efficiency of the first heat exchanger 15a can be increased. Thus, by increasing the temperature of the intake air flowing to the exhaust circuit 16 by bypass, the volume is further expanded, and the rotational speed of the turbocharger 11 is further increased, so that the heat energy of the recirculated exhaust gas can be more effectively used.

Further, by connecting the supply / exhaust bypass circuit 20 to a position of the intake circuit 12 upstream of the aftercooler 13, a part of the intake air cooled by the aftercooler 13 flows to the supply / exhaust bypass circuit 20, and is re-established. 1 heat exchanger 1
There is no waste such as heating at 5a, and the heat balance of the aftercooler 13 can be improved. That is, the exhaust circuit 15
In order to reduce the flow rate of the intake air passing through the aftercooler 13, the intake air temperature after passing the air cooler 13 becomes lower. As a result, the combustion temperature is further reduced, and the generation of NO _X can be suppressed more remarkably. In addition, since the intake pressure at the connection position of the exhaust gas recirculation circuit can be adjusted by adjusting the opening of the throttle valve, the range of the operating state in which the exhaust gas can be recirculated is widened. Therefore, from low speed / low load area to high speed / low load
By operating the exhaust gas recirculation device under a wide range of operating conditions up to a high load region, harmful components in the exhaust gas can be reduced.

A second embodiment of the present invention will be described with reference to FIG. The same components as those described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. A venturi 12b having a narrow portion is provided in the intake circuit 12 upstream of the intake manifold 12a. An intake bypass circuit 12c is provided between the immediately upstream side and the downstream side of the venturi 12b sandwiching the narrow portion, and an intake bypass circuit 12c is provided to open and close the intake bypass circuit 12c. A controlled intake bypass valve 12d is provided. In the supply / exhaust bypass circuit 20, a check valve 2 is provided instead of the supply / exhaust bypass valve 20a.
0b is provided. The check valve 20b allows only one-way flow from the intake circuit 12 to the exhaust circuit 16. The exhaust gas recirculation circuit 15 is connected to the intake circuit 12 at a substantially central portion of the narrow portion of the venturi 12b.

Only when the detection means 31 detects that the pressure of the intake manifold 12a is higher than the pressure of the exhaust manifold 16a and it is necessary to recirculate the exhaust gas,
The control unit 33 throttles the intake bypass valve 12d. When the intake bypass valve 12d is throttled, the flow rate through the intake bypass circuit 12c decreases, and the flow rate through the venturi 12b increases accordingly. Therefore, the flow velocity in the narrow portion increases, and the connection position of the narrow portion, that is, the connection position of the exhaust recirculation circuit 15 is reduced. The pressure drops. At the same time, the check valve 20b opens due to the pressure difference between the intake manifold 12a and the exhaust manifold 16a, and the compressor 11
Part of the intake air pressurized by a flows through the air supply / exhaust bypass circuit 20 to the exhaust circuit 16, and reduces the pressure of the intake manifold 12a and increases the pressure of the exhaust manifold 16a. 2 above
The exhaust recirculation circuit 15 and the intake circuit 12
Can be made equal to or less than the pressure at the connection point between the exhaust gas recirculation circuit 15 and the exhaust circuit 12, so that exhaust gas can be recirculated.

Further, the check valve 20b is opened, and a part of the intake air pressurized by the compressor 11a is
When the exhaust gas flows through the exhaust circuit 16 through the
Cooling by the heat exchanger 15a is the same as in the first embodiment. When the pressure of the intake manifold 12a becomes equal to or lower than the pressure of the exhaust manifold 16a, the check valve 20b does not open, so that no flow occurs in the supply / exhaust bypass circuit 20.

According to the second embodiment, in addition to the effects of the first embodiment, the supply / exhaust bypass circuit 20 is opened and closed by a simple element called the check valve 20b, so that the structure can be simplified. Further, the flow rate of the intake air can be increased in the narrow portion of the venturi 12b provided in the intake circuit 12, and the pressure thereof can be partially reduced, and an exhaust recirculation circuit is connected substantially at the center of the narrow portion. Therefore, by adjusting the opening of the intake bypass valve 12d, the flow rate of the intake air passing through the narrow portion can be adjusted, and the intake pressure at the narrow portion, that is, the connection position of the exhaust recirculation circuit can be freely adjusted. The range of operating conditions in which the recirculation is possible is widened. Therefore, harmful components in the exhaust gas can be reduced by operating the exhaust gas recirculation device under a wide range of operating conditions from a low speed / low load region to a high speed / high load region.

As described above with reference to the embodiments, according to the present invention, the following effects can be obtained. (1) The recirculated exhaust gas is passed through both the first heat exchanger and the second heat exchanger arranged in series. Therefore,
Even in an operation state in which the pressure on the intake side is lower than the pressure on the exhaust side, no flow occurs in the supply / exhaust bypass circuit and the cooling effect of the first heat exchanger cannot be obtained, the water-cooled second heat exchanger is used. The recirculating exhaust gas can be cooled. Further, in an operating state in which the intake side pressure is higher than the exhaust side, a flow occurs in the supply / exhaust bypass circuit, and the cooling effect of the first heat exchanger is obtained, and the first heat exchanger and the second heat exchange Since the recirculated exhaust gas can be cooled by both the heat exchanger and the heat exchanger, the cooling capacity of the first heat exchanger can be reduced, that is, the outer dimensions can be reduced as compared with the case where the second heat exchanger is not provided. Usually, the first heat exchanger of the air-cooled type has a lower cooling efficiency than the second heat exchanger of the water-cooled type, and tends to be inevitably larger. However, according to the present invention, the load on the cooling capacity is reduced. By reducing the size, the contribution to the miniaturization of the entire apparatus also increases. Furthermore, the first heat exchanger is located upstream of the second heat exchanger and introduces high-temperature exhaust gas, so that the temperature difference between the recirculated exhaust gas and the bypassed intake air is widened, and the first heat exchanger is compared with the second heat exchanger. As a result, the cooling efficiency of the inferior first heat exchanger can be increased. Thus, the temperature of the intake air flowing into the exhaust circuit by bypass is further increased to expand the volume, and the rotational speed of the turbocharger is further increased, so that the heat energy of the recirculated exhaust gas can be more effectively used. At the same time, the temperature of the exhaust gas introduced into the second heat exchanger decreases,
The temperature rise of the cooling water in the second heat exchanger can be suppressed, and the supply flow rate of the cooling water and, if there is a radiator, the burden on the radiator can be minimized.

(2) The heat balance of the aftercooler can be improved by connecting the air supply / exhaust bypass circuit to the position of the intake circuit upstream of the aftercooler. That is, the temperature of the intake air after passing through the aftercooler is reduced to reduce the flow rate of the intake air passing through the aftercooler by an amount corresponding to the bypass to the exhaust circuit. As a result, the combustion temperature is further reduced, and the generation of NO _X can be suppressed more remarkably.

(3) If the supply / exhaust bypass valve is replaced with a check valve, the supply / exhaust bypass circuit is opened and closed by a simple element called a check valve, so that the structure can be simplified. In addition, a venturi having a narrow portion in the intake circuit, an intake bypass circuit for bypassing the venturi, and an intake bypass valve having a variable opening area so that the intake bypass circuit can be opened and closed are provided. The exhaust recirculation circuit is connected at the approximate center of the section. that way,
The flow rate of intake air passing through the narrow part can be adjusted by adjusting the opening degree of the intake bypass valve, and the flow rate of the intake air can be increased by increasing the flow velocity of the intake air in the narrow part of the venturi, and the narrow part can be freely adjusted. That is, the intake pressure at the position where the exhaust gas recirculation circuit is connected can be adjusted. Therefore, harmful components in the exhaust gas can be reduced by operating the exhaust gas recirculation device under a wide range of operating conditions from a low speed / low load region to a high speed / high load region. Even if a throttle valve is provided in the intake circuit instead of the combination of the venturi and the intake bypass circuit and an exhaust recirculation circuit is connected between the throttle valve and the engine body,
The same effect can be obtained because the intake pressure at the position where the exhaust gas recirculation circuit is connected can be reduced by the resistance of the throttle valve.

The embodiments of the present invention are not limited to the above two embodiments. For example, an aftercooler may not necessarily be provided, and the throttle valve in the first embodiment may be replaced with a fixed throttle having a fixed opening. Further, in the above two embodiments, the refrigerant of the second heat exchanger is the engine cooling water. However, as long as continuous supply is possible without impeding operation, for example, water supply, cooling tower, water supply vehicle,
Cooling water serving as a coolant may be introduced from a water source such as the sea, a river, or a lake.

[Brief description of the drawings]

FIG. 1 is a supply and exhaust circuit diagram of a first embodiment of the present invention.

FIG. 2 is a supply / exhaust circuit diagram of a second embodiment of the present invention.

FIG. 3 is a diagram of a supply / exhaust circuit of the prior art.

[Explanation of symbols]

11 Turbocharger, 11a Compressor, 11
b: turbine, 12: intake circuit, 12b: venturi,
12c: intake bypass circuit, 12d: intake bypass valve,
15: exhaust gas recirculation circuit, 15a: first heat exchanger, 15b
... second heat exchanger, 17 ... throttle valve, 20 ... supply / exhaust bypass circuit, 20a ... supply / exhaust bypass valve, 20b ... check valve.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G005 EA04 EA16 GB03 GB18 GD13 GD14 HA12 JA24 JA25 JA28 3G062 AA05 BA00 BA06 CA07 CA08 DA01 ED04 ED08 ED10

Claims (5)

[Claims] A compressor (1) disposed on an intake circuit (12).
1a) and a turbocharger (11) having a turbine (11b) disposed on an exhaust circuit (16), and a turbine (11
b) -the internal combustion engine body (14a) and the compressor (11a) of the intake circuit (12) -the internal combustion engine body (14a) are connected to form a first on-off valve.
(15c) an exhaust recirculation circuit (15) that can be opened and closed freely,
Between the turbine (11b) of the exhaust circuit (16) and the internal combustion engine body (14a) and between the compressor (11a) of the intake circuit (12) and the internal combustion engine body (14a)
And a supply / exhaust bypass circuit (20) that can be opened and closed by a second opening / closing valve (20a) by connecting between the exhaust gas recirculation circuit (15) and the supply / exhaust bypass circuit (20). An exhaust gas recirculation control device for an internal combustion engine having a first heat exchanger (15a) for performing exchange, a second heat exchanger (15b) for cooling recirculated exhaust gas in an exhaust gas recirculation circuit (15) using water as a refrigerant. At an exhaust recirculation circuit (15) downstream of the first heat exchanger (15a). 2. A compressor (11a) -an internal combustion engine main body (14a).
An aftercooler (13) for cooling intake air is provided between the compressor and the intake / exhaust bypass circuit (20) with respect to the intake circuit (12) between the compressor (11a) and the aftercooler (13). Item 2. An exhaust gas recirculation control device for an internal combustion engine according to Item 1. 3. A compressor (11a) -an internal combustion engine main body (14a).
A throttle (12b) having a narrow portion for narrowing the flow of intake air is provided in the intake circuit (12), and the connection position of the exhaust recirculation circuit (15) is set to approximately the center of the narrow portion, and immediately upstream of the throttle (12b) An intake bypass circuit (12c) is provided, which is bypass-connected to the immediately downstream side and can be opened and closed by a third on-off valve (12d). The connection position of the supply / exhaust bypass circuit (20) to the intake circuit (12) is 3. The exhaust gas recirculation control device for an internal combustion engine according to claim 1, wherein the distance is set between 11a) and a throttle (12b). 4. A compressor (11a) -an internal combustion engine main body (14a).
A throttle valve (17) is provided in the intake circuit (12) to reduce the flow of intake air between the throttle valve (17) and the internal combustion engine body (14a). The exhaust gas recirculation control for an internal combustion engine according to claim 1 or 2, wherein a connection position of the supply / exhaust bypass circuit (20) to the (12) is located between the compressor (11a) and the throttle valve (17). apparatus. 5. The second on-off valve (20a) is a turbocharger.
The check valve (20b), which allows a flow in only one direction from the downstream side of the compressor (11a) to the upstream side of the turbine (11b) of (11), characterized in that it is a check valve (20b), The exhaust gas recirculation control device for an internal combustion engine according to claim 3 or 4.