JP2008255957A - Exhaust gas recirculation device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device of an internal combustion engine capable of inhibiting liquefaction of moisture in exhaust gas in an EGR passage with a simple construction. <P>SOLUTION: The exhaust gas recirculation device of the internal combustion engine is applied to the internal combustion engine 1 having a turbocharger 7 and has the EGR passage 20 recirculating the exhaust gas from an exhaust passage 4 to an intake passage 3 upstream of the turbocharger 7. The EGR passage 20 is provided with a heat exchange part 30 performing heat exchange between intake air compressed in the turbocharger 7 and the exhaust gas passing through the EGR passage 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine having an EGR passage that communicates an exhaust passage and an intake passage.

  The exhaust passage downstream of the turbocharger turbine and the intake passage upstream of the turbocharger compressor are connected to the low pressure exhaust gas recirculation passage, and the exhaust passage upstream of the turbine and the intake passage downstream of the compressor are connected. An internal combustion engine having a high-pressure exhaust gas recirculation passage is known (see Patent Document 1). In an internal combustion engine having an EGR passage that connects the exhaust passage and the intake passage, the exhaust gas is cooled in the EGR passage when the recirculation of the exhaust gas is stopped or when the flow rate of the recirculated exhaust gas is small. Water in the inside may liquefy and water may be generated in the EGR passage. This water has various effects on the internal combustion engine. For example, if sulfur acid or nitrogen oxide in the exhaust gas is mixed with water generated in the EGR passage and the acidity becomes high, corrosion of intake system components provided in the intake passage may progress due to the water. Therefore, an exhaust gas recirculation device is known in which an EGR passage upstream of an EGR valve and a downstream EGR passage are arranged close to each other in order to prevent moisture liquefaction in the EGR passage (see Patent Document 2). There is also known a heat exchange device that is provided with a refrigeration cycle in which refrigerant circulates and heats the exhaust gas that has passed through the EGR valve by the heat of the exhaust gas flowing into the EGR valve using this refrigeration cycle (see Patent Document 3). In addition, Patent Documents 4 and 5 exist as prior art documents related to the present invention.

Japanese Patent Laying-Open No. 2005-076456 Japanese Patent Laid-Open No. 06-288305 JP 09-032653 A Japanese Patent Laid-Open No. 10-196464 Japanese Patent Laid-Open No. 11-093781

  In the device of Patent Document 2, the EGR passage on the upstream side of the EGR valve and the EGR passage on the downstream side are arranged close to each other, but heat is transferred from these upstream EGR passages to the downstream EGR passage. Since it is performed by air, heat transfer efficiency is poor. In the apparatus of Patent Document 3, since it is necessary to provide a refrigeration cycle in which the refrigerant circulates, the apparatus becomes complicated.

  Therefore, an object of the present invention is to provide an exhaust gas recirculation device for an internal combustion engine that can suppress liquefaction of moisture in exhaust gas in an EGR passage with a simple configuration.

  The first exhaust gas recirculation device of the present invention is applied to an internal combustion engine provided with a supercharger, and exhaust gas of an internal combustion engine provided with an EGR passage that recirculates exhaust gas from an exhaust passage to an intake passage upstream of the supercharger. In the recirculation device, the EGR passage is provided with a heat exchanging portion that performs heat exchange between the intake air compressed in the supercharger and the exhaust gas flowing through the EGR passage. (Claim 1).

  As is well known, in the supercharger, the intake air is compressed and its temperature rises. According to the first exhaust gas recirculation device of the present invention, heat exchange can be performed between the intake air whose temperature has increased and the exhaust gas flowing through the EGR passage, thereby suppressing a decrease in the temperature of the EGR passage, The temperature of the exhaust gas can be maintained at a temperature higher than the temperature at which moisture is liquefied. Therefore, liquefaction of moisture in the exhaust gas in the EGR passage can be suppressed. In addition, heat exchange between the intake air and the exhaust gas can be performed in this way to reduce the intake air temperature, thereby suppressing an increase in the intake air temperature, thereby suppressing a decrease in the intake air amount taken into the cylinder of the internal combustion engine. it can. Therefore, it is possible to suppress a decrease in the output of the internal combustion engine.

  In one form of the first exhaust gas recirculation device of the present invention, an EGR cooler that cools exhaust gas is provided in the EGR passage, and the heat exchanging portion is provided in an EGR passage downstream of the EGR cooler. Good (claim 2). In this case, the temperature of the exhaust gas that has been cooled by the EGR cooler and whose moisture has been easily liquefied can be raised in the heat exchange section. Therefore, liquefaction of moisture in the exhaust can be more appropriately suppressed.

  In one form of the first exhaust gas recirculation device of the present invention, the supercharger is a turbocharger, and the compressor housing of the turbocharger has an exhaust outlet portion that opens to an intake air introduction passage of the compressor housing. At one end and an exhaust inlet portion into which the exhaust led from the exhaust passage is introduced at the other end, and disposed along at least a part of the scroll chamber of the compressor housing, and downstream of the EGR passage An exhaust heating passage that forms a part of the exhaust heating passage is provided, and the heat exchanging portion may be the exhaust heating passage. As is well known, since the intake air is compressed in the scroll chamber of the compressor housing, the temperature of the intake air rises. The compressor housing is also heated by the compression of the intake air. Therefore, an exhaust heating passage is provided in the compressor housing, and heat exchange between the exhaust and the intake air is performed in the exhaust heating passage. This can prevent the EGR passage from being unnecessarily lengthened. Further, by cooling the intake air at an early stage when the intake air is compressed by the compressor of the turbocharger, more intake air can be compressed. Therefore, the output of the internal combustion engine can be improved.

  A second exhaust gas recirculation device according to the present invention includes an EGR pipe that forms an EGR passage that communicates an exhaust passage and an intake passage, and an EGR cooler that is provided in the EGR pipe and cools exhaust gas. In the exhaust gas recirculation apparatus, the downstream EGR pipe, which is an EGR pipe downstream from the EGR cooler, receives heat generated from the exhaust gas in the upstream EGR pipe, which is an EGR pipe upstream from the EGR cooler. The above-described problem is solved by providing the heat transfer section that transmits the side EGR pipe (claim 4).

  According to the second exhaust gas recirculation device of the present invention, the heat of the exhaust gas in the upstream EGR pipe can be transmitted to the downstream EGR pipe by the heat transfer unit. Therefore, the temperature drop of the downstream EGR pipe can be suppressed, and the temperature of the exhaust gas that has passed through the EGR cooler where the moisture in the exhaust gas is liable to be liquefied can be maintained higher than the temperature at which the moisture is liquefied. Therefore, liquefaction of moisture in the exhaust can be suppressed with a simple configuration.

  In one form of the second exhaust gas recirculation apparatus of the present invention, the downstream EGR pipe and the upstream EGR pipe are provided with contact portions each having a flat outer surface, respectively, and the downstream EGR pipe and the upstream EGR pipe are provided. The side EGR pipe is disposed so that the contact portion of the downstream EGR pipe and the contact portion of the upstream EGR pipe are in contact with each other, and the heat transfer portion may be the contact portion. . As described above, by providing the contact portions on the downstream EGR pipe and the upstream EGR pipe and bringing these contact portions into contact with each other, the heat of the exhaust gas in the upstream EGR pipe can be transmitted to the downstream EGR pipe. Moreover, since the outer surface of the contact part is each formed in the plane, a contact area can be increased. Therefore, heat can be quickly transferred from the upstream EGR pipe to the downstream EGR pipe. Therefore, liquefaction of moisture in the exhaust can be suppressed with a simple configuration.

  In one form of the second exhaust gas recirculation apparatus of the present invention, the flow passage cross-sectional area of at least a part of the upstream EGR pipe is set larger than the flow passage cross-sectional area of the downstream EGR pipe, In that section, the downstream EGR pipe penetrates through the upstream EGR pipe along the upstream EGR pipe, and the heat transfer section has the downstream EGR pipe penetrates through the upstream EGR pipe. It may be a penetrating part (claim 6). In this case, since the downstream EGR pipe penetrates the inside of the upstream EGR pipe, the penetration portion of the downstream EGR pipe can be heated by the exhaust gas inside the upstream EGR pipe. Therefore, liquefaction of moisture in the exhaust can be suppressed.

  In an embodiment of the second exhaust gas recirculation apparatus of the present invention, a plate member is provided as the heat transfer portion, one end of which contacts the upstream EGR pipe and the other end of which contacts the downstream EGR pipe. (Claim 7). In this case, heat can be transmitted from the upstream EGR pipe to the downstream EGR pipe via the plate member. Therefore, this heat can suppress a decrease in the temperature of the downstream EGR pipe. Therefore, it is possible to suppress the liquefaction of moisture in the exhaust gas from the downstream EGR pipe with a simple configuration.

  In this embodiment, the one end is in contact with the upstream EGR pipe and the other end is in contact with the downstream EGR pipe, and at least one of the one end and the other end is separated from the EGR pipe. Drive means for driving the plate member between positions may be further provided (claim 8). In this case, unnecessary heat transfer to the downstream EGR pipe can be prevented by driving the plate member to the separated position. Therefore, useless heating of the EGR gas can be prevented and useless rise of the intake air temperature can be prevented. Accordingly, it is possible to suppress a decrease in the amount of intake air sucked into each cylinder and suppress a decrease in the output of the internal combustion engine. On the other hand, since the downstream EGR pipe can be heated by driving the plate member to the contact position, it is possible to suppress a decrease in the temperature of the downstream EGR pipe and suppress liquefaction of moisture in the exhaust gas.

  The apparatus may further include a control unit that controls the driving unit so that the plate member is driven to the separation position when it is determined that the temperature of the downstream EGR pipe is higher than a predetermined temperature set in advance. (Claim 9). If the temperature of the exhaust gas discharged from the internal combustion engine is high, such as during high load operation of the internal combustion engine, if the heat of the exhaust gas in the upstream EGR pipe is transmitted to the downstream EGR pipe, the temperature of the downstream EGR pipe will rise too much. The exhaust is heated wastefully. In this embodiment, when it is determined that the temperature of the downstream EGR pipe is higher than the predetermined temperature in this way, the plate member is driven to the separated position, so that wasteful heating of the exhaust can be prevented. As a result, a decrease in the output of the internal combustion engine can be suppressed.

  As described above, according to the exhaust gas recirculation apparatus of the present invention, the exhaust gas flowing through the EGR passage can be heated with a simple configuration, so that the moisture in the exhaust gas can be prevented from being liquefied in the EGR passage. . In addition, by exchanging heat between the intake air flowing through the intake passage and the exhaust flowing through the EGR passage, or when the temperature of the downstream EGR pipe is high, the transfer of heat to the downstream EGR pipe is stopped. Output reduction can be suppressed.

(First form)
FIG. 1 is a schematic view showing an internal combustion engine in which an exhaust gas recirculation apparatus according to a first embodiment of the present invention is incorporated. An internal combustion engine (hereinafter sometimes referred to as an engine) 1 in FIG. 1 is mounted on a vehicle as a power source for traveling, and includes an engine body 2 provided with a plurality of cylinders (not shown), An intake passage 3 and an exhaust passage 4 connected to the cylinders are provided. In the intake passage 3, an intake duct 5 provided with an air filter for intake air filtration, a throttle valve 6 for adjusting the intake air amount, a compressor 7a of the turbocharger 7, and an intercooler for cooling the intake air 8 are provided. The exhaust passage 4 is provided with a turbine 7b of the turbocharger 7, a bypass passage 9 that bypasses the turbine 7b and guides exhaust gas downstream of the turbine 7b, and a waste gate valve 10 that opens and closes the bypass passage 9. Yes. The turbocharger 7 includes a rotating shaft 7c that connects the compressor wheel of the compressor 7a and the turbine wheel of the turbine 7b so as to rotate together, and a center housing 7d that is provided with a bearing that rotatably holds the rotating shaft 7c. It has. In addition, since these may be the same as a well-known internal combustion engine, detailed description is abbreviate | omitted.

  The exhaust passage 4 and the intake passage 3 are connected by an EGR passage 11 for returning a part of the exhaust gas to the intake passage 3. As shown in FIG. 1, one end 20a of the EGR passage 20 is connected to the intake passage 3 between the throttle valve 6 and the compressor 7a, and the other end 20b is connected to the exhaust passage 4 downstream of the turbine 7b. That is, in the engine 1, a part of the exhaust discharged from the turbine 7b is recirculated upstream of the compressor 7a. Hereinafter, the exhaust gas recirculated to the intake passage 3 via the EGR passage 20 may be referred to as EGR gas. The EGR passage 20 is provided with an EGR cooler 21 for cooling the EGR gas and an EGR valve 22 for adjusting the flow rate of the EGR gas recirculated to the intake passage 3.

  As shown in FIG. 1, a heat exchange unit 30 is provided in the EGR passage 20 on the downstream side of the EGR cooler 21. As is well known, the temperature of the intake air compressed by the compressor 7a rises. The heat exchanging unit 30 heats the EGR gas by exchanging heat between the compressed intake air and the EGR gas. Therefore, the heat exchanging unit 30 is provided in the intake passage 3 on the downstream side of the compressor 7a. The heat exchange unit 30 is provided by, for example, winding the EGR pipe forming the EGR passage 20 a plurality of times while contacting the outer periphery of the intake pipe forming the intake passage 3.

  According to the exhaust gas recirculation apparatus according to the first embodiment, since the heat exchange unit 30 is provided in the EGR passage 20, the EGR gas can be heated by the compressed intake air in the heat exchange unit 30. Therefore, it can suppress that the water | moisture content in EGR gas liquefies. In the heat exchanging unit 30, the EGR gas is heated by the heat of the intake air that has been compressed and the temperature thereof has increased, so that the temperature of the EGR gas can be raised and the temperature of the intake air can be lowered by this heat exchange. That is, the EGR gas heated by the heat exchange unit 30 is compressed by the compressor 7 a and then cooled by the heat exchange unit 30. As is well known, the amount of intake air taken into the cylinder increases as the temperature of the intake air decreases, so that the output of the engine 1 improves. Therefore, the output of the engine 1 can be improved by reducing the temperature of the intake air in the heat exchanging unit 30.

  In FIG. 1, the EGR passage 20 is provided around the intake passage 3 to exchange heat between the compressed intake air and the EGR gas. However, the heat exchange unit 30 is not limited to this. For example, various structures that can exchange heat between the compressed intake air and the EGR gas, such as passing the EGR passage 20 through the intake passage 3, may be used. In addition, as shown in FIG. 2, a heat exchanger 31 may be provided as a heat exchange unit in the EGR passage 20 on the downstream side of the EGR cooler 21. An EGR passage 20 downstream of the EGR cooler 21 and an intake passage 3 downstream of the compressor 7 a are connected to the heat exchanger 31, and compressed intake air flowing through the intake passage 3 and EGR flowing through the EGR passage 20 Exchange heat with the gas.

  FIG. 3 shows a main part of a modification of the exhaust gas recirculation apparatus according to the first embodiment. FIG. 3 is a cross-sectional view of the compressor 7a of the turbocharger 7. In this modification, an exhaust heating passage 41 for circulating EGR gas is provided in the compressor housing 40 of the turbocharger 7, and heat exchange between the intake air and the EGR gas is performed in the exhaust heating passage 41. One end of the exhaust heating passage 41 opens into the intake air introduction passage 40a of the compressor housing 40 to form an exhaust outlet portion 41a. The other end of the exhaust heating passage 41 is provided with an exhaust inlet portion 41 b to which an EGR pipe that forms the EGR passage 20 on the downstream side of the EGR cooler 21 is connected and exhaust from the exhaust passage 4 is introduced. Therefore, the exhaust heating passage 41 forms a part of the EGR passage 20. Further, as shown in FIG. 2, the exhaust heating passage 41 is formed in the compressor housing 41 and is provided along the scroll chamber 40 b in which the intake air guided by the rotation of the compressor wheel 42 is compressed. In this case, the EGR gas passes through the EGR cooler 21 and the EGR valve 22, is guided to the exhaust heating passage 41, passes through the exhaust heating passage 41, and is then discharged from the exhaust outlet 41a to the intake passage.

  According to this modification, heat exchange can be performed between the exhaust gas guided to the exhaust gas heating passage 41 and the intake air compressed in the scroll chamber 40b, thereby suppressing the liquefaction of moisture in the EGR gas. Can do. Moreover, since the intake air compressed in the scroll chamber 40b can be cooled, the volume of the intake air can be reduced. Therefore, the supercharging efficiency can be improved. In this case, the exhaust heating passage 41 corresponds to the heat exchange section of the present invention.

(Second form)
FIG. 4 shows a schematic view of an internal combustion engine in which an exhaust gas recirculation apparatus according to the second embodiment of the present invention is incorporated. In FIG. 4, the same parts as those in FIG. In the second embodiment, heat exchange is performed between the EGR passage 20 upstream of the EGR cooler 21 and the EGR passage 20 downstream of the EGR cooler 21. Therefore, the EGR passage 20 downstream of the EGR cooler 21 has one end 50 a in contact with the EGR passage 20 upstream from the EGR cooler 21 and the other end 50 b in contact with the EGR passage 20 downstream from the EGR cooler 21. A heat transfer plate 50 as a member is provided. The heat transfer plate 50 is made of a material having a high thermal conductivity, for example, a metal. 5 and 6 are enlarged views of the heat transfer plate 50. FIG. 6 is a cross-sectional view of the heat transfer plate 50 taken along the line VI-VI in FIG. As shown in FIGS. 5 and 6, the heat transfer plate 50 forms an upstream EGR pipe 60 that forms an EGR passage 20 upstream of the EGR cooler 21 and an EGR passage 20 that is downstream of the EGR cooler 21. It is provided so as to span the downstream EGR pipe 61. The heat transfer plate 50 is fixed to the EGR pipes 60 and 61 with one end 50 a in contact with the upstream EGR pipe 60 and the other end 50 b in contact with the downstream EGR pipe 61.

  By providing the heat transfer plate 50 in this way, even if the EGR valve 22 is switched to the fully closed state and the exhaust gas recirculation is stopped, the heat of the exhaust gas guided into the upstream EGR pipe 60 is downstream via the heat transfer plate 50. Can be transmitted to the side EGR pipe 61. Therefore, a decrease in the temperature of the downstream EGR pipe 61 can be suppressed. Thereby, the liquefaction of the moisture in the exhaust gas staying in the downstream EGR pipe 61 can be suppressed. Thus, by transferring the heat of the upstream EGR pipe 60 to the downstream EGR pipe 61, the heat transfer plate 50 functions as a heat transfer portion of the present invention.

  A modification of the exhaust gas recirculation apparatus according to the second embodiment will be described with reference to FIGS. FIG. 8 is a cross-sectional view of the EGR tubes 60 and 61 taken along the line VIII-VIII in FIG. 7 and 8, the same reference numerals are given to the portions common to FIGS. 5 and 6, and the description thereof is omitted. As shown in FIG. 8, the downstream EGR pipe 61 is provided with a contact portion 61a whose outer surface is formed as a flat surface. Similarly, the upstream EGR pipe 60 is provided with a contact portion 60a having a flat outer surface. As shown in FIGS. 7 and 8, the upstream EGR pipe 60 and the downstream EGR pipe 61 are arranged such that the contact portions 60a and 61a are in contact with each other. Further, the upstream EGR pipe 60 is arranged vertically below the downstream EGR pipe 61.

  According to this modification, the heat of the exhaust gas in the upstream EGR pipe 60 can be transmitted to the downstream EGR pipe 61 via the contact portions 60a and 61a. Therefore, a decrease in the temperature of the downstream EGR pipe 61 can be suppressed. Therefore, it is possible to suppress liquefaction of moisture in the exhaust gas staying in the downstream EGR pipe 61. As shown in FIG. 8, the downstream EGR pipe 61 is arranged so that the contact portion 61a is positioned vertically downward, so that water in the exhaust gas is liquefied in the downstream EGR pipe 61 to generate water. In that case, the water accumulates in the contact portion 61a. Further, since the upstream EGR pipe 60 is disposed vertically below the downstream EGR pipe 61, the downstream EGR pipe 61 can be heated from below vertically. Therefore, even if water is generated in the downstream EGR pipe 61, the water can be quickly heated and vaporized. In this case, the contact part 61a functions as a heat transfer part of the present invention.

  FIG. 9 shows another modification of the exhaust gas recirculation apparatus according to the second embodiment. In FIG. 9, the same reference numerals are given to the same parts as in FIG. As shown in FIG. 9, in this modification, the flow passage cross-sectional area is set larger than the flow passage cross-sectional area of the downstream EGR pipe 61 in a part of the upstream EGR pipe 60, and the downstream EGR pipe 61. Are arranged so as to penetrate through the upstream EGR pipe 60 along the upstream EGR pipe 60 in the section. That is, in that section, the EGR passage 20 is formed as a double pipe in which the downstream EGR pipe 61 is inserted inside the upstream EGR pipe 60.

  According to this modification, the downstream EGR pipe 61 can be heated by the exhaust gas in the upstream EGR pipe 60 in the section formed as a double pipe. Therefore, the temperature drop of the downstream EGR pipe 61 can be suppressed and liquefaction of moisture in the exhaust can be suppressed. In this case, the penetration part 61b which is a part of the downstream EGR pipe 61 penetrating the inside of the upstream EGR pipe 60 functions as a heat transfer part of the present invention.

  FIG. 10 shows still another modification of the exhaust gas recirculation apparatus according to the second embodiment. In FIG. 10, parts common to FIGS. 5 and 6 are denoted by the same reference numerals and description thereof is omitted. In this modification, the heat transfer plate 50 is not fixed to the upstream EGR pipe 60 and the downstream EGR pipe 61, and the position of the heat transfer plate 50 can be changed according to the operating state of the engine 1. Therefore, as shown in FIG. 10, in this modification, an actuator 70 is provided as a driving means for driving the heat transfer plate 50. The actuator 70 has a contact position P1 at which one end 50a of the heat transfer plate 50 contacts the upstream EGR pipe 60 and the other end 50b contacts the downstream EGR pipe 61, the heat transfer plate 50, and each EGR pipe 60, 61. The heat transfer plate 50 is driven between the separation position P2 and the separation position P2.

  The operation of the actuator 70 is controlled by an engine control unit (ECU) 80 as control means. The ECU 80 is a well-known computer unit that controls the operating state of the engine 1 according to a predetermined control program. When the temperature of the exhaust gas discharged from the engine body 2 is high, there is a possibility that the temperature of the EGR gas becomes unnecessarily high when the downstream EGR pipe 61 is heated. Therefore, the ECU 80 controls the operation of the actuator 70 based on the temperature of the downstream EGR pipe 61, for example. This control will be specifically described. As is well known, when the load on the engine 1 is high, the temperature of the exhaust discharged from the engine body 2 becomes high. Therefore, it can be determined that the temperature of the downstream EGR pipe 61 also increases. Therefore, the ECU 80 estimates the load of the engine 1 based on the intake air amount and the like, and operates the actuator 70 so that the heat transfer plate 50 is driven to the separation position P2 when the estimated load is larger than a preset determination value. To control. On the other hand, when the load of the engine 1 is less than or equal to the allowable value, the temperature of the downstream EGR pipe 61 decreases, and the moisture in the exhaust gas may be liquefied in the downstream EGR pipe 61. The operation of the actuator 70 is controlled so as to be driven by P1.

  According to this modification, when the load on the engine 1 is high and the temperature of the exhaust gas discharged from the engine body 2 is high, the heat transfer plate 50 is driven to the separation position P2 by the actuator 70. Heating can be prevented. Therefore, it is possible to prevent a reduction in the output of the engine 1 by suppressing a wasteful increase in the intake air temperature. On the other hand, when the load on the engine 1 is low and the temperature of the exhaust gas discharged from the engine body 2 is low, the heat transfer plate 50 is driven to the contact position P1, so the downstream EGR pipe 61 is heated to the downstream EGR. A decrease in the temperature of the tube 61 can be suppressed. Therefore, it is possible to suppress the moisture in the exhaust gas from being liquefied in the downstream EGR pipe 61.

  It should be noted that both ends of the heat transfer plate 50 may not be separated from the EGR gas pipes 60 and 61 at the separated position. For example, at the separation position, one end 50 a of the heat transfer plate 50 may be separated from the upstream EGR pipe 60, or the other end 50 b of the heat transfer plate 50 may be separated from the downstream EGR pipe 61. Even in such a state, heat transfer from the upstream EGR pipe 60 to the downstream EGR pipe 61 can be prevented. Further, the driving means for driving the heat transfer plate 50 may not be the actuator 70. For example, the heat transfer plate 50 may be driven using a bimetal or a shape memory alloy. In this case, for example, a bimetal or a shape memory alloy may be provided so that the other end of the heat transfer plate 50 is separated from the downstream EGR pipe 61 when the temperature of the downstream EGR pipe 61 becomes equal to or higher than a predetermined temperature set in advance. In this case, bimetal or shape memory alloy functions as the driving means of the present invention.

  This invention is not limited to each form mentioned above, It can implement with a various form. For example, the supercharger provided in the internal combustion engine to which the present invention is applied is not limited to a turbocharger. The present invention may be applied to an internal combustion engine provided with various superchargers that compress intake air, such as a supercharger that compresses intake air using rotation of a crankshaft of the internal combustion engine. Further, the heat source of heat transferred to the downstream EGR pipe is not limited to intake air or EGR gas. Various things that become higher than the outside air temperature during operation of the engine may be used as a heat source. For example, an exhaust manifold that collects exhaust exhausted from each cylinder, an engine block that forms the engine body, and a downstream EGR pipe span a heat transfer plate, and the EGR gas is heated by the heat of these parts. May be.

The figure which shows the outline of the internal combustion engine in which the exhaust gas recirculation apparatus which concerns on the 1st form of this invention was integrated. The figure which shows the modification of the exhaust gas recirculation apparatus which concerns on a 1st form. The figure which shows the principal part of the other modification of the exhaust gas recirculation apparatus which concerns on a 1st form. The figure which shows the outline of the internal combustion engine in which the exhaust gas recirculation apparatus which concerns on the 2nd form of this invention was integrated. The figure which expands and shows the heat-transfer board of FIG. The figure which shows the cross section of the heat-transfer board in the VI-VI line of FIG. The figure which shows the principal part of the modification of the exhaust gas recirculation apparatus which concerns on a 2nd form. The figure which shows the cross section of the EGR pipe | tube in the VIII-VIII line of FIG. The figure which shows the other modification of the exhaust gas recirculation apparatus which concerns on a 2nd form. The figure which shows the further another modification of the exhaust gas recirculation apparatus which concerns on a 2nd form.

Explanation of symbols

1 Internal combustion engine 3 Intake passage 4 Exhaust passage 7 Turbocharger 20 EGR passage 21 EGR cooler 30 Heat exchange section 31 Heat exchanger (heat exchange section)
40 Compressor housing 40a Intake inlet passage 40b Scroll chamber 41 Exhaust heating passage 41a Exhaust outlet portion 41b Exhaust inlet portion 50 Heat transfer plate (plate member, heat transfer portion)
50a one end 50b other end 60 upstream EGR pipe 60a contact part 61 downstream EGR pipe 61a contact part (heat transfer part)
61b Penetration part (heat transfer part)
70 Actuator (drive means)
80 Engine control unit (control means)
P1 contact position P2 separation position

Claims (9)

In an exhaust gas recirculation apparatus for an internal combustion engine, which is applied to an internal combustion engine including a supercharger and includes an EGR passage that recirculates exhaust gas from an exhaust passage to an intake passage upstream of the supercharger.
The exhaust gas recirculation of the internal combustion engine, wherein the EGR passage is provided with a heat exchange section for exchanging heat between the intake air compressed in the supercharger and the exhaust gas flowing through the EGR passage. apparatus. The EGR passage is provided with an EGR cooler for cooling the exhaust,
2. The exhaust gas recirculation apparatus for an internal combustion engine according to claim 1, wherein the heat exchange unit is provided in an EGR passage downstream of the EGR cooler. The supercharger is a turbocharger;
The compressor housing of the turbocharger has at one end an exhaust outlet portion that opens to the intake air introduction passage of the compressor housing and at the other end an exhaust inlet portion into which the exhaust led from the exhaust passage is introduced. And an exhaust heating passage disposed along at least a portion of the scroll chamber of the compressor housing to form a part of the downstream portion of the EGR passage,
The exhaust gas recirculation apparatus for an internal combustion engine according to claim 1 or 2, wherein the heat exchange section is the exhaust heating passage. In an exhaust gas recirculation apparatus for an internal combustion engine, comprising: an EGR pipe that forms an EGR passage that communicates an exhaust passage and an intake passage; and an EGR cooler that is provided in the EGR pipe and cools exhaust gas.
The downstream EGR pipe, which is an EGR pipe downstream from the EGR cooler, transfers heat generated from the exhaust gas in the upstream EGR pipe, which is an upstream EGR pipe from the EGR cooler, to the downstream EGR pipe. An exhaust gas recirculation apparatus for an internal combustion engine, characterized in that a heat transfer section is provided. The downstream EGR pipe and the upstream EGR pipe are each provided with a contact portion having a flat outer surface,
The downstream EGR pipe and the upstream EGR pipe are arranged such that a contact portion of the downstream EGR pipe and a contact portion of the upstream EGR pipe are in contact with each other,
The exhaust gas recirculation apparatus for an internal combustion engine according to claim 4, wherein the heat transfer portion is the contact portion. The flow path cross-sectional area of at least a part of the upstream EGR pipe is set larger than the flow path cross-sectional area of the downstream EGR pipe, and the downstream EGR pipe passes through the upstream EGR pipe in the section. Penetrates along the upstream EGR pipe,
5. The exhaust gas recirculation apparatus for an internal combustion engine according to claim 4, wherein the heat transfer portion is a through portion in which the downstream EGR pipe passes through the upstream EGR pipe.   The exhaust of the internal combustion engine according to claim 4, wherein a plate member having one end contacting the upstream EGR pipe and the other end contacting the downstream EGR pipe is provided as the heat transfer portion. Reflux apparatus.   Between the contact position where the one end contacts the upstream EGR pipe and the other end contacts the downstream EGR pipe, and the separation position where at least one of the one end and the other end is separated from the EGR pipe 8. The exhaust gas recirculation device for an internal combustion engine according to claim 7, further comprising a driving means for driving the plate member.   The apparatus further comprises control means for controlling the driving means so that the plate member is driven to the separated position when it is determined that the temperature of the downstream EGR pipe is higher than a predetermined temperature set in advance. The exhaust gas recirculation device for an internal combustion engine according to claim 8.

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