Exhaust gas recirculation device for internal combustion engine

Abstract

To introduce EGR gas to an intake passage while generation of condensation water is suppressed even when a temperature of cooling water is low.SOLUTION: An internal combustion engine 1 includes an exhaust gas recirculation device 200. The exhaust gas recirculation device 200 includes: an EGR passage 10 for introducing part of exhaust gas to an intake passage 4 as EGR gas; an EGR cooler 12 provided in the EGR passage 10 to exchange heat between cooling water of the internal combustion engine 1 and the EGR gas; and an EGR valve 230 provided in the EGR passage 10 between the intake passage 4 and the EGR cooler 12. The EGR valve 230 includes: a temperature sensitive part with which the EGR gas comes into contact; and a valve element that opens when a temperature of the EGR gas coming into contact with the temperature sensitive part is higher than a prescribed temperature to allow a flow of the EGR gas.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

Background Art

[0002] As described in Patent Document 1, an exhaust gas recirculation device having an EGR passage for introducing a part of the exhaust gas of an internal combustion engine into the intake passage as EGR gas is known. This exhaust gas recirculation device includes an EGR cooler provided in the EGR passage for performing heat exchange between the cooling water of the internal combustion engine and the EGR gas. Further, this exhaust gas recirculation device includes an EGR valve for opening and closing the EGR passage. This EGR valve has a valve actuator that deforms according to the temperature of the cooling water and a valve body. Then, when the temperature of the cooling water becomes equal to or higher than a predetermined value, the valve actuator deforms and the valve body is opened, so that EGR gas is introduced into the intake passage. When EGR gas is introduced into the intake passage by such an exhaust gas recirculation device, the combustion temperature of the air-fuel mixture decreases, so that the amount of NOx generated in the internal combustion engine decreases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the temperature of the EGR gas passing through the EGR cooler becomes equal to or lower than the dew point temperature, condensed water is generated in the EGR gas. Therefore, when the temperature of the EGR gas is equal to or lower than the dew point temperature, usually, the EGR valve is closed.

[0005] Incidentally, the higher the EGR gas flow rate in the EGR passage, the lower the cooling efficiency of the EGR cooler. Therefore, when passing through the EGR cooler, the temperature of the EGR gas is less likely to decrease, and the temperature of the EGR gas may exceed the dew point temperature. In such a state where the temperature of the EGR gas is high, it is possible to introduce the EGR gas because condensed water is less likely to be generated. However, in the above conventional technology, when the cooling water temperature of the internal combustion engine is low, the EGR valve does not open, so even in a state where condensed water is less likely to be generated, the EGR gas cannot be introduced.

Means for Solving the Problems

[0006] The exhaust gas recirculation device of an internal combustion engine for solving the above problems includes an EGR passage that introduces a part of the exhaust gas of the internal combustion engine into the intake passage as EGR gas, an EGR cooler provided in the EGR passage for performing heat exchange between the cooling water of the internal combustion engine and the EGR gas, and an EGR valve provided in the EGR passage between the intake passage and the EGR cooler. And the EGR valve has a temperature sensing part that contacts the EGR gas, and a valve body that opens when the temperature of the EGR gas contacting the temperature sensing part is higher than a predetermined temperature to allow the flow of the EGR gas.

Effects of the Invention

[0007] This exhaust gas recirculation device of an internal combustion engine can introduce EGR gas into the intake passage in a state where the generation of condensed water is suppressed even when the temperature of the cooling water is low.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment in which an exhaust gas recirculation device of an internal combustion engine is embodied will be described with reference to FIGS. 1 to 3. <Configuration of Internal Combustion Engine> FIG. 1 shows an internal combustion engine 1 provided with an exhaust gas recirculation device in the present embodiment. The internal combustion engine 1 is an internal combustion engine that uses hydrogen gas as fuel.

[0010] The internal combustion engine 1 includes a fuel injection valve 5 that supplies hydrogen gas, which is engine fuel, to the combustion chamber. An intake passage 4 is connected to the internal combustion engine 1. A surge tank 2 is provided in the middle of the intake passage 4. Further, a throttle valve 3 for measuring the intake air amount is provided in the intake passage 4 on the upstream side of the surge tank 2.

[0011] An exhaust passage 6 is connected to the internal combustion engine 1. A supercharger 13 for supercharging the intake air using the exhaust pressure is provided in the middle of the exhaust passage 6. The supercharger 13 is a well-known variable displacement supercharger and can adjust the supercharging pressure.

[0012] The supercharger 13 includes a compressor housing 13a that houses a compressor wheel 13c and a turbine housing 13b that houses a turbine wheel 13t. The turbine housing 13b is provided in the middle of the exhaust passage 6. A catalyst 7 for purifying the exhaust gas is provided in the exhaust passage 6 downstream of the turbine housing 13b.

[0013] The compressor housing 13a is provided in the middle of the intake passage 4. An intercooler 14 is provided in the intake passage 4 between the compressor housing 13a and the throttle valve 3. The intake air heated up by supercharging is cooled by the intercooler 14.

[0014] The internal combustion engine 1 is provided with an exhaust gas recirculation device (hereinafter referred to as the EGR device) that introduces a part of the exhaust gas into the intake passage 4 as EGR gas. The EGR device 200 has an EGR passage 10 that introduces EGR gas into the intake passage 4.

[0015] The EGR passage 10 is a passage branched from the exhaust passage 6 downstream of the turbine housing 13b and is connected to the intake passage 4 upstream of the compressor housing 13a. An EGR cooler 12 for performing heat exchange between the cooling water of the internal combustion engine 1 and the EGR gas is provided in the middle of the EGR passage 10. The EGR cooler 12 is connected to a cooling water circuit 300 through which the cooling water of the internal combustion engine 1 circulates.

[0016] An EGR valve 230 for opening and closing the EGR passage 10 is provided in the EGR passage 10 between the intake passage 4 and the EGR cooler 12. The structure of the EGR valve 230 will be described later. When the EGR valve 230 opens, a part of the exhaust gas passing through the exhaust passage 6 flows into the EGR passage 10 as EGR gas. The EGR gas flowing into the EGR passage 10 is heat-exchanged by the EGR cooler 12 and then introduced into the intake passage 4 and introduced into the combustion chamber of the internal combustion engine 1 again together with the fresh air. When the EGR gas is introduced into the combustion chamber, the combustion temperature of the air-fuel mixture decreases, so the generation of NOx in the internal combustion engine 1 is suppressed.

[0017] The operating state of the internal combustion engine 1 and the like are detected by various sensors. For example, the crank angle sensor 60 detects the crank angle which is the rotation angle of the crankshaft of the internal combustion engine 1. Further, the air flow meter 61 detects the intake air amount GA which is the amount of air inhaled into the internal combustion engine 1. Further, the water temperature sensor 64 detects the water temperature THW which is the temperature of the cooling water of the internal combustion engine 1. Further, the air-fuel ratio sensor 65 is provided in the exhaust passage 6 upstream of the catalyst 7 and detects the air-fuel ratio AF. Further, the accelerator sensor 67 detects the accelerator operation amount ACCP which is the depression amount of the accelerator pedal. Further, the throttle sensor 68 detects the throttle opening TA which is the opening degree of the throttle valve 3.

[0018] The control device 100 controls the internal combustion engine 1. And the control device 100 operates various operation target devices such as the throttle valve 3, the fuel injection valve 5, the ignition plug of the internal combustion engine 1, and the supercharger 13.

[0019] The control device 100 includes a CPU 110 that performs arithmetic processing, a memory 120 in which control programs and data are stored, and the like. And the control device 100 executes processing related to various controls by the CPU 110 executing the programs stored in the memory 120.

[0020] Detection signals of the various sensors described above are input to the control device 100. Hydrogen gas, which is the engine fuel, has a wider range of combustible mixtures compared to gasoline and can burn even with a lean mixture. Therefore, the control device 100 adjusts the output of the internal combustion engine 1 through the following combustion control.

[0021] That is, the control device 100 calculates a required output Pe, which is a required value of the engine output of the internal combustion engine 1, based on the accelerator operation amount ACCP or the like. The control device 100 sets a required injection amount Qd based on the required output Pe. The required injection amount Qd is the target value of the fuel injected from the fuel injection valve 5. The control device 100 calculates a required air amount GAd, which is the target value of the intake air amount required to obtain the target air-fuel ratio AFt, based on the target air-fuel ratio AFt and the required injection amount Qd. The target air-fuel ratio AFt of the present embodiment is a lean air-fuel ratio such as an air excess ratio λ = 2.5 to 3.0. Then, the control device 100 controls the fuel injection valve 5 so that the required injection amount Qd is obtained. Further, the control device 100 controls the opening degree of the throttle valve 3 and the supercharging pressure of the supercharger 13 so that the required air amount GAd is obtained. Thus, in the internal combustion engine 1, the output is adjusted by changing the air-fuel ratio of the air-fuel mixture through the adjustment of the fuel injection amount and the intake air amount.

[0022] <Structure of EGR valve> FIG. 2 shows the cross-sectional structure of the EGR valve 230. As shown in the figure, the EGR valve 230 includes a housing 220 that forms a part of the EGR passage 10. The housing 220 is formed, for example, in a tubular shape, one end of which is an inlet 221 through which the EGR gas that has passed through the EGR cooler 12 flows in, and the other end of which is an outlet 222 through which the EGR gas flows out toward the EGR passage 10 connected to the intake passage 4.

[0023] Inside the housing 220, a displaceable valve body 223 is installed. The valve body 223 is provided with a through-hole 229. This through-hole 229 is provided so that a minute amount of EGR gas can pass through the valve body 223. As a result, even when the valve body 223 is closed, the EGR gas that has passed through the EGR cooler 12 comes into contact with a temperature-sensitive portion 227 described later. The diameter of the through-hole 229 is set as follows, for example. That is, even if the EGR gas passing through the through-hole 229 contains condensed water when the valve body 223 is closed, the amount of the contained condensed water is less than the minimum value of the amount of condensed water that adversely affects the internal combustion engine 1. Thus, the diameter of the through-hole 229 is set. Examples of the condensed water adversely affecting the internal combustion engine 1 include corrosion of parts, occurrence of misfire, erosion of the compressor wheel 13c, and the like.

[0024] On the inner wall of the housing 220, a valve seat 224 against which the valve body 223 can abut is provided. When the valve body 223 is in a position abutting against the valve seat 224, it is in a closed state, blocking the flow of EGR gas from the inlet 221 to the outlet 222. Further, when the valve body 223 is in a position separated from the valve seat 224, it is in an open state, allowing the flow of EGR gas from the inlet 221 to the outlet 222.

[0025] A spring seat 225 is installed in a portion of the housing 220 on the outlet 222 side of the valve body 223. A plurality of holes penetrate through the spring seat 225. Due to the presence of these holes, the flow of EGR gas from the upstream side to the downstream side of the housing 220 with respect to the spring seat 225 is allowed. Note that a gap may be provided between the spring seat 225 and the inside of the housing 220 to allow the flow of EGR gas from the upstream side to the downstream side of the housing 220 with respect to the spring seat 225.

[0026] A spring 226 that biases the valve body 223 toward the valve seat 224 is interposed between the valve body 223 and the spring seat 225. A temperature-sensitive part 227 is installed in a portion between a valve body 223 and a spring seat 225 inside a housing 220. The temperature-sensitive part 227 is fixed to the valve body 223 in a state of being arranged downstream of the valve body 223 in the flow direction of the EGR gas, and is inserted into the spring seat 225 so as to be relatively movable with respect to the spring seat 225.

[0027] Inside the temperature-sensitive part 227, wax which is a temperature-sensitive material is encapsulated. Further, a guide bar 228 fixed to the housing 220 is inserted into the temperature-sensitive part 227. The wax encapsulated inside the temperature-sensitive part 227 solidifies and shrinks when the temperature of the EGR gas in contact with the temperature-sensitive part 227 is low, and melts and expands when the temperature is high.

[0028] When the insertion amount of the guide bar 228 into the temperature-sensitive part 227 changes due to such a volume change of the wax, the temperature-sensitive part 227 is displaced together with the valve body 223. Due to such displacement of the valve body 223, the opening and closing of the valve body 223 in the EGR valve 230 are performed. More specifically, when the temperature of the EGR gas reaches a predetermined valve opening temperature Tref, the wax melts and expands, whereby the valve body 223 opens. The valve opening temperature Tref is, for example, the lowest temperature of the EGR gas at which generation of condensed water can be suppressed.

[0029] In this way, the valve body 223 is configured as a valve body that opens to allow the flow of the EGR gas when the temperature of the EGR gas in contact with the temperature-sensitive part 227 is higher than the predetermined valve opening temperature Tref.

[0030] <Operation of this Embodiment> FIG. 3 shows the transition of each value after the start of the engine is started. Hereinafter, a state where the EGR gas flow rate in the EGR passage 10 is large is hereinafter referred to as a high flow rate, and a state where the EGR gas flow rate in the EGR passage 10 is small compared to this high flow rate is hereinafter referred to as a low flow rate. Note that, as a state where the EGR gas flow rate increases, there is a state where the exhaust flow rate increases. Examples of the state where the exhaust flow rate increases include a state where the internal combustion engine 1 is operating at a high rotation speed or a state where it is operating at a high load.

[0031] The line L1 shown in FIG. 3(A) indicates the change in the water temperature of the cooling water supplied to the EGR cooler 12. The line L2 shown in FIG. 3(A) indicates the change in the gas temperature of the EGR gas that has passed through the EGR cooler 12 at high flow rates. The line L3 shown in FIG. 3(A) indicates the change in the gas temperature of the EGR gas that has passed through the EGR cooler 12 at low flow rates. The line L4 shown in FIG. 3(B) indicates the change in the pressure loss of the EGR passage 10 at high flow rates. The line L5 shown in FIG. 3(B) indicates the change in the pressure loss of the EGR passage 10 at low flow rates.

[0032] As shown in FIG. 3, when the engine start is initiated at time t0, the temperature of the cooling water of the internal combustion engine 1 rises, so the water temperature of the EGR cooler 12 indicated by the line L1 also rises. Then, when the rise in the temperature of the cooling water subsides, the rise in the water temperature of the EGR cooler 12 also subsides.

[0033] In accordance with such an increase in the water temperature of the EGR cooler 12, the gas temperature of the EGR gas also rises. Here, since the cooling efficiency of the EGR cooler is high at low flow rates, the difference between the water temperature of the EGR cooler 12 and the gas temperature of the EGR gas is small as indicated by the lines L1 and L3. Then, when the gas temperature reaches the valve opening temperature Tref at time t2, the EGR valve 230 starts to open. As a result, as indicated by the line L5, the pressure loss of the EGR passage 10 begins to decrease and the introduction of the EGR gas is started. After that, when the EGR valve 230 is fully open, the decrease in the pressure loss of the EGR passage 10 subsides and reaches a certain value. At low flow rates, the difference between the water temperature of the EGR cooler 12 and the gas temperature of the EGR gas is small. Therefore, the valve opening timing of the EGR valve 230 is the same as that of the EGR valve configured such that the temperature sensing part 227 is hit by the cooling water instead of the EGR gas.

[0034] On the other hand, at high flow rates, the cooling efficiency of the EGR cooler decreases. Therefore, as shown by lines L1 and L2, the difference between the water temperature of the EGR cooler 12 and the gas temperature of the EGR gas increases, and when passing through the EGR cooler 12, the temperature of the EGR gas is less likely to drop. Therefore, the temperature of the EGR gas exceeds the dew point temperature. In a state where the temperature of the EGR gas is high in this way, since condensed water is less likely to be generated, it is possible to introduce the EGR gas. And at high flow rates, since the gas temperature of the EGR gas is higher than that at low flow rates, the gas temperature reaches the above-mentioned valve opening temperature Tref at time t1, which is earlier than time t2. When the gas temperature reaches the above-mentioned valve opening temperature Tref, the EGR valve 230 starts to open. As a result, as shown by line L4, the pressure loss of the EGR passage 10 begins to decrease and the introduction of the EGR gas is started. The introduction timing of the EGR gas at this high flow rate is earlier than the introduction timing of the EGR gas at low flow rates. And when the EGR valve 230 is fully open, the decrease in the pressure loss of the EGR passage 10 stops and becomes a certain value.

[0035] <Effects of the present embodiment> (1) When the temperature of the EGR gas in contact with the temperature sensing part is higher than a predetermined temperature, the valve body of the EGR valve opens. Therefore, even when the temperature of the cooling water is low, the EGR gas can be introduced into the intake passage in a state where the generation of condensed water is suppressed.

[0036] (2) At high flow rates where the EGR gas flow rate in the EGR passage 10 is large, compared with low flow rates where the EGR gas flow rate is small, the timing of introducing the EGR gas into the intake passage 4 becomes earlier. Therefore, a large amount of EGR gas can be introduced into the intake passage 4 at an early stage.

[0037] (3) The valve body 223 is a valve body having a through hole 229. Therefore, even when the valve body 223 is closed, the EGR gas flows through the through hole 229, so a flow of the EGR gas occurs in the EGR valve 230. Therefore, even when the valve body 223 is closed, the EGR gas comes into contact with the temperature sensing part 227, so that the opening and closing of the valve body 223 can be performed according to the temperature of the EGR gas.

[0038] (4) The EGR valve 230 has its valve element 223 opened and closed by the temperature sensing portion 227. Therefore, it is less expensive compared to an EGR valve in which the opening and closing of the valve element is controlled using a solenoid valve or the like, but it is inferior in terms of the controllability of the amount of gas introduced when introducing EGR gas.

[0039] In this regard, the internal combustion engine 1 is an internal combustion engine that uses hydrogen gas as fuel. In the internal combustion engine 1 that uses hydrogen gas as fuel, the range of the combustible air-fuel mixture is wider and the resistance to misfire is higher compared to an internal combustion engine that uses gasoline as fuel. Therefore, precise controllability of the amount of gas is not required when introducing EGR gas. Therefore, in the present embodiment, in the EGR device 200 of the internal combustion engine 1 that uses such hydrogen gas as fuel, the EGR valve 230 having the temperature sensing portion 227 described above is provided. Accordingly, an inexpensive EGR valve can be adopted while suppressing the occurrence of misfire.

[0040] (5) When an EGR valve in which the opening and closing of the valve element is controlled using a solenoid valve or the like is adopted, the man-hours for developing a program for controlling the solenoid valve, the man-hours for obtaining an appropriate value during control, a drive circuit for driving the solenoid valve, etc. are required, so the cost is high. In this regard, since the valve element 223 of the EGR valve 230 of the present embodiment is opened and closed by the temperature sensing portion 227, such an increase in cost can be suppressed.

[0041] <Modification example> Note that the present embodiment can be implemented with the following modifications. The present embodiment and the following modification examples can be implemented in combination with each other within a range where there is no technical contradiction.

[0042] · The internal combustion engine 1 may perform combustion with an air-fuel mixture having an air-fuel ratio of 1 or less when the EGR valve 230 is open. FIG. 4 shows the procedure of the process executed by the control device 100 to implement this modification example. The process shown in FIG. 2 is realized by the CPU 110 executing the program stored in the memory 120 of the control device 100 at a predetermined cycle. Hereinafter, the step numbers of each process are represented by numbers preceded by "S".

[0043] In the series of processes shown in FIG. 4, the control device 100 determines whether or not the EGR valve 230 is open (S100). In the process of S100, a method for determining whether or not the EGR valve 230 is open can be appropriately adopted. For example, when EGR gas is introduced into the intake passage 4 by the opening of the EGR valve 230, the air-fuel ratio AF detected by the air-fuel ratio sensor 65 changes. Therefore, when the control device 100 determines that such a change in the air-fuel ratio AF has been detected, it determines that the EGR valve 230 is open.

[0044] If it is determined in the process of S100 that the EGR valve 230 is open (S100: YES), the control device 100 performs stoichiometric combustion (S110). Stoichiometric combustion is an example of combustion with an air-fuel mixture having an air excess ratio of 1 or less. The control device 100 performs stoichiometric combustion by adjusting the opening degree of the throttle valve 3 and the amount of fuel injected from the fuel injection valve 5. As the process of S110, rich combustion, which is an example of combustion with an air-fuel mixture having an air excess ratio of 1 or less, may be performed.

[0045] On the other hand, if it is not determined in the process of S100 that the EGR valve 230 is open (S100: NO), the control device 100 performs lean combustion (S120). Lean combustion is combustion with an air-fuel mixture having an air excess ratio exceeding 1. In the present embodiment, as the lean combustion by the process of S120, lean burn, which is combustion with an air-fuel mixture having an air excess ratio greatly exceeding 1, is executed. The control device 100 performs lean burn by adjusting the opening degree of the throttle valve 3 and the amount of fuel injected from the fuel injection valve 5.

[0046] Then, when the control device 100 executes the process of S110 or the process of S120, this process is terminated once. According to this modification example, when the EGR valve 230 is open, combustion is performed with an air-fuel mixture having an air-fuel ratio of 1 or less. That is, stoichiometric combustion or rich combustion is performed. These stoichiometric combustion and rich combustion have a higher engine output than lean combustion, which is combustion with an air-fuel mixture having an air-fuel ratio greatly exceeding 1, while the amount of NOx generated tends to increase. In this regard, in this modification example, when the EGR valve 230 is open and EGR gas is introduced, combustion is performed with an air-fuel mixture having an air-fuel ratio of 1 or less. Therefore, it is possible to suppress the generation of NOx while increasing the engine output.

[0047] · In the above embodiment, the through hole 229 was provided in the valve body 223. In addition, the EGR valve 230 may have a bypass passage through which the EGR gas flows around the valve body 223. Fig. 5 shows the cross-sectional structure of the EGR valve 230 in this modification example. As shown in Fig. 5, the valve body 223 of the EGR valve 230 in this modification example does not include the through hole 229. And, a bypass passage 240 is integrally formed in the housing 220 of the EGR valve 230. The bypass passage 240 is a passage through which the EGR gas flowing in from the inlet 221 flows around the valve body 223 and flows out to the outlet 222. It is desirable to set the formation direction of the bypass passage 240 so that the EGR gas flowing out from the bypass passage 240 heads toward the temperature sensing portion 227. Also, the bypass passage 240 may be provided separately from the housing 220 of the EGR valve 230 instead of being integrally formed.

[0048] In this modification example, even when the valve body 223 is closed, the EGR gas passes through the bypass passage 240 and flows inside the EGR valve 230, so a flow of the EGR gas occurs inside the EGR valve 230. Therefore, even when the valve body 223 is closed, the EGR gas comes into contact with the temperature sensing portion 227, so that the opening and closing of the valve body 223 can be performed according to the temperature of the EGR gas.

[0049] Note that the EGR valve 230 may have both the valve body 223 having the through hole 229 and the bypass passage 240. · The internal combustion engine 1 was an internal combustion engine that uses hydrogen gas as fuel, but it may also be an internal combustion engine that uses other fuels. Even in this case, the effects other than the above (4) can be obtained.

[0050] · The temperature-sensitive material included in the temperature-sensitive part 227 was wax, but it may have other temperature-sensitive materials. Examples of other temperature-sensitive materials include shape memory alloys and bimetals. · The EGR device 200 was a low-pressure type exhaust gas recirculation device in which the EGR passage 10 branched from the exhaust passage 6 downstream of the turbine housing 13b was connected to the intake passage 4 upstream of the compressor housing 13a. Alternatively, the EGR device 200 may be a high-pressure type exhaust gas recirculation device in which the EGR passage 10 branched from the exhaust passage 6 upstream of the turbine housing 13b is connected to the intake passage 4 downstream of the throttle valve 3 or the surge tank 2.

[0051] · The control device 100 includes a CPU 110 and a memory 120, and executes software processing. However, this is merely an example. The control device 100 may include, for example, a dedicated hardware circuit (such as an ASIC, etc.) that processes at least a part of the software processing executed in the above embodiment. That is, the control device 100 may have any of the following configurations (a) to (c). (a) It includes a processing device that executes all of the above processing according to a program, and a program storage device such as a memory that stores the program. (b) It includes a processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It includes a dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software circuits including a processing device and a program storage device, and a plurality of dedicated hardware circuits. That is, the above processing may be executed by a processing circuit including at least one of one or more software circuits and one or more dedicated hardware circuits. The program storage device, that is, the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0052] <Supplementary Notes> Describe the technical idea that can be grasped from the above embodiment and modification examples. [Appendix 1] An exhaust gas recirculation device for an internal combustion engine, comprising an EGR passage that introduces a part of the exhaust gas of the internal combustion engine into an intake passage as EGR gas, an EGR cooler provided in the EGR passage for performing heat exchange between the cooling water of the internal combustion engine and the EGR gas, and an EGR valve provided in the EGR passage between the intake passage and the EGR cooler, wherein the EGR valve has a temperature sensing part that the EGR gas contacts, and a valve body that opens when the temperature of the EGR gas contacting the temperature sensing part is higher than a predetermined temperature to allow the flow of the EGR gas. An exhaust gas recirculation device for an internal combustion engine.

[0053] [Appendix 2] The temperature sensing part is arranged downstream of the valve body in the flow direction of the EGR gas, and the valve body is a valve body having a through hole. The exhaust gas recirculation device of an internal combustion engine according to Appendix 1.

[0054] [Appendix 3] The temperature sensing part is arranged downstream of the valve body in the flow direction of the EGR gas, and the EGR valve has a bypass passage through which the EGR gas flows around the valve body. The exhaust gas recirculation device of an internal combustion engine according to Appendix 1 or Appendix 2.

[0055] [Appendix 4] The internal combustion engine is an internal combustion engine that uses hydrogen gas as fuel. The exhaust gas recirculation device of an internal combustion engine according to any one of Appendices 1 to 3. [Appendix 5] The internal combustion engine performs combustion with an air-fuel ratio of 1 or less when the EGR valve is open. The exhaust gas recirculation device of an internal combustion engine according to any one of Appendices 1 to 4.

Description of Reference Numerals

[0056] 1... Internal combustion engine 4... Intake passage 6... Exhaust passage 7... Catalyst 10... EGR passage 12... EGR cooler 13... Supercharger 100... Control device 110... CPU 120... Memory 200... Exhaust gas recirculation device (EGR device) 220... Housing 221... Inlet 222... Outlet 223... Valve body 224... Valve seat 225... Spring seat 226... Spring 227... Temperature sensing part 228... Guide bar 229... Through hole 230... EGR valve 240... Bypass passage 300... Cooling water circuit

Claims

1. An exhaust gas recirculation device for an internal combustion engine, comprising: an EGR passage for introducing a part of the exhaust gas of the internal combustion engine into the intake passage as EGR gas; an EGR cooler provided in the EGR passage for performing heat exchange between the cooling water of the internal combustion engine and the EGR gas; an EGR valve provided in the EGR passage between the intake passage and the EGR cooler, wherein the EGR valve has a temperature sensing portion contacted by the EGR gas, and a valve body that opens to allow the flow of the EGR gas when the temperature of the EGR gas contacting the temperature sensing portion is higher than a predetermined temperature. An exhaust gas recirculation device for an internal combustion engine.

2. The temperature sensing portion is disposed downstream of the valve body in the flow direction of the EGR gas, and the valve body is a valve body having a through hole. The exhaust gas recirculation device for an internal combustion engine according to Claim 1.

3. The temperature sensing portion is disposed downstream of the valve body in the flow direction of the EGR gas, and the EGR valve has a bypass passage through which the EGR gas flows around the valve body. The exhaust gas recirculation device for an internal combustion engine according to Claim 1.

4. The internal combustion engine is an internal combustion engine using hydrogen gas as fuel. The exhaust gas recirculation device for an internal combustion engine according to Claim 1.

5. The internal combustion engine performs combustion with an air-fuel ratio of 1 or less when the EGR valve is open. The exhaust gas recirculation device for an internal combustion engine according to Claim 1.

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