JP2017133382A - Warming-up promotion system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more efficiently promote warming-up of an internal combustion engine.SOLUTION: A first flow passage control mechanism 40 changes a flow passage area of an exhaust passage LA for discharging exhaust gas discharged from an internal combustion engine 20 to outside of a vehicle. A second flow passage control mechanism 42 changes a flow passage area of an exhaust recirculation passage LB that is branched from the exhaust passage LA to recirculate the exhaust gas to an intake passage LD of the internal combustion engine 20. A third flow passage control mechanism 44 changes a flow passage area of a bypass passage LC that is branched from the exhaust recirculation passage LB to discharge the exhaust gas to the exhaust passage LA without recirculating the exhaust gas to the intake passage LD. An exhaust gas cooler 26 for cooling the exhaust gas by using a cooling medium is provided in the exhaust recirculation passage LB. When a temperature of the cooling medium is less than a prescribed temperature, each of the flow passage control mechanisms restricts the flow passage area of each of the flow passages to raise pressure in a region R, so as to promote heat exchange in the exhaust gas cooler 26.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a warm-up promotion system that promotes warm-up of an internal combustion engine.

Conventionally, a warming-up acceleration technology that promotes warm-up immediately after starting an internal combustion engine and reduces friction to improve fuel efficiency has been studied.
For example, Patent Literature 1 below has a plurality of cooling medium passages through which a cooling medium is introduced into an internal combustion engine, and among these cooling medium passages, a cooling medium flowing through a first cooling medium passage connected to a cylinder block is provided. In the EGR cooler, heat is exchanged with the exhaust. Since the temperature of the cooling medium is increased by exhaust, warming up of the cylinder block is promoted, and a temperature difference is provided between the other parts of the internal combustion engine and each part is brought into an appropriate temperature state.

JP 2011-47305 A

  By using the exhaust heat of the EGR cooler for warming up the internal combustion engine as in the prior art described above, warmup can be promoted without complicating the vehicle configuration. On the other hand, in the above-described conventional technology, there is room for improvement in performing warm-up more efficiently.

  The present invention has been made in view of such circumstances, and an object thereof is to more efficiently promote warm-up of an internal combustion engine.

In order to achieve the above object, a warm-up promoting system for an internal combustion engine according to the invention of claim 1 is a first flow for changing a flow passage area of an exhaust passage through which exhaust gas discharged from the internal combustion engine is discharged outside the vehicle. A flow path area of a path adjustment mechanism and an exhaust gas recirculation path that branches from the exhaust passage upstream of the first flow path adjustment mechanism and returns the exhaust gas to the intake passage of the internal combustion engine is changed. A second flow path adjustment mechanism and the exhaust gas recirculation passage on the upstream side of the exhaust gas flow from the second flow path adjustment mechanism, and the exhaust gas flow downstream of the first flow path adjustment mechanism A third flow path adjusting mechanism for changing a flow path area of the bypass passage connected to the exhaust passage, and a cooling medium provided on the exhaust gas recirculation passage on the upstream side of the exhaust gas flow from a branch with the bypass passage; The exhaust gas is cooled by An exhaust cooler, and a cooling path that connects the exhaust cooler and the internal combustion engine and enables heat exchange between the cooling medium and the internal combustion engine, and the temperature of the cooling medium is less than a predetermined temperature. In this case, the first flow path adjustment mechanism, the second flow path adjustment mechanism, and the third flow path adjustment mechanism limit the flow area of each flow path.
In the internal combustion engine warm-up promoting system according to the invention of claim 2, the third flow path adjustment mechanism is more bypassed than the flow path area of the exhaust passage limited by the first flow path adjustment mechanism. The flow path area is increased.
An internal combustion engine warming-up promotion system according to a third aspect of the invention includes a pressure in the exhaust passage on the upstream side of the exhaust gas flow of the first flow path adjustment mechanism, and the exhaust of the second flow rate adjustment mechanism. A pressure sensor for detecting any one of a pressure in the exhaust gas recirculation passage on the upstream side of the gas flow and a pressure in the bypass passage on the upstream side of the exhaust gas flow of the third flow rate adjustment mechanism; In addition, when the pressure is equal to or higher than a predetermined pressure, the third flow path adjustment mechanism expands the flow path area of the bypass passage, and the region even after the flow path area of the bypass passage is maximized. When the inside is equal to or higher than the predetermined pressure, the first flow path adjustment mechanism enlarges the flow path area of the exhaust passage.
According to a fourth aspect of the present invention, in the internal combustion engine warm-up promoting system, when the temperature of the cooling medium is equal to or higher than the predetermined temperature, the first flow path adjustment mechanism is configured such that the temperature of the cooling medium is the predetermined temperature. The flow passage area of the exhaust passage is made larger than when it is less than that.

According to the first aspect of the present invention, an area surrounded by the first flow path adjustment mechanism, the second flow path adjustment mechanism, and the third flow path adjustment mechanism (hereinafter simply referred to as “area”), that is, an exhaust cooler. Therefore, the exhaust gas temperature in this region rises and the flow rate of the exhaust gas in this region decreases. As a result, the amount of heat transferred from the exhaust gas to the cooling medium in the exhaust cooler increases, and the temperature of the cooling medium is raised more quickly than simply introducing the exhaust gas into the exhaust gas recirculation passage, thereby warming up the internal combustion engine. This is advantageous.
According to the invention of claim 2, the flow passage area of the bypass passage is made larger than the flow passage area of the exhaust passage. For this reason, the amount of exhaust gas introduced from the exhaust recirculation passage to the bypass passage is smaller than the amount of exhaust gas introduced from the exhaust passage to the exhaust recirculation passage, and the pressure in the region is reliably increased. Is advantageous.
According to the invention of claim 3, since the pressure is adjusted by the flow path adjusting mechanism when the pressure in the region becomes too high, damage to the piping due to excessive pressure is prevented, and the durability of the warm-up promoting system is improved. It is advantageous in improving Moreover, since the opening degree of the first flow path adjustment mechanism is increased after the third flow path adjustment mechanism is fully opened, the pressure in the region is adjusted without reducing the amount of exhaust gas introduced into the exhaust gas recirculation passage as much as possible. This is advantageous in warming up the internal combustion engine in a short time.
According to the invention of claim 4, when the temperature of the cooling medium becomes equal to or higher than a predetermined temperature, the amount of exhaust gas introduced into the exhaust gas recirculation passage is reduced, and the amount of heat exchange with the cooling medium in the exhaust cooler is reduced. . This is advantageous in preventing heat transfer from the cooling medium to the internal combustion engine and maintaining the internal combustion engine at an appropriate temperature.

It is explanatory drawing which shows the structure of the warming-up promotion system 10 concerning embodiment. It is explanatory drawing which shows the functional structure of ECU50. 2 is an explanatory diagram showing a state of a warm-up promotion system 10 during a warm-up operation of the internal combustion engine 20. FIG. It is explanatory drawing which shows the state when a load is given to the internal combustion engine 20 during warm-up operation.

Exemplary embodiments of a warm-up promoting system for an internal combustion engine according to the present invention will be explained below in detail with reference to the accompanying drawings.
In the following description, “upstream” and “downstream” refer to “exhaust gas flow upstream” and “exhaust gas flow downstream”, respectively.
Drawing 1 is an explanatory view showing the composition of warm-up promotion system 10 concerning an embodiment.
The exhaust gas discharged from the internal combustion engine (engine) 20 passes through the exhaust passage LA and is discharged outside the vehicle. On the exhaust passage LA, the catalyst 22 that purifies harmful components in the exhaust gas by reduction and oxidation, the first flow path adjustment mechanism 40 that adjusts the flow path area of the exhaust passage LA, and the exhaust gas are discharged to the outside. A muffler 24 is provided to reduce the sound generated at the time.

In the exhaust passage LA, an exhaust gas recirculation passage LB for returning the exhaust gas to the intake passage LD of the internal combustion engine 20 branches from a location P1 upstream of the first flow path adjustment mechanism 40 in the exhaust gas flow. In the present embodiment, the exhaust gas recirculation passage LB is located upstream of the first flow path adjustment mechanism 40 and downstream of the catalyst 22. Exhaust gas used for combustion again in the internal combustion engine 20 through the exhaust gas recirculation passage LB becomes exhaust gas recirculation (EGR) gas.
The amount of exhaust gas recirculated to the intake passage LD of the internal combustion engine 20 is adjusted by using a second flow path adjustment mechanism (EGR valve) 42 that changes the flow path area of the exhaust gas recirculation path LB. The second flow path adjustment mechanism 42 is provided downstream of the branch position P2 with the bypass path LC described later in the exhaust gas recirculation path LB.

An exhaust cooler 26 for cooling the high-temperature exhaust gas is provided on the exhaust recirculation passage LB. A cooling medium such as a coolant circulates in the exhaust cooler 26, and the cooling medium and the exhaust gas exchange heat to cool the exhaust gas.
An exhaust cooler cooling path 28 through which a cooling medium circulates is connected to the exhaust cooler 26. The exhaust cooler cooling path 28 connects the exhaust cooler 26 and the internal combustion engine 20, and enables heat exchange between the cooling medium passing through the exhaust cooler 26 and the internal combustion engine 20.
In order to circulate the cooling medium in the exhaust cooler cooling passage 28 and actively exchange heat with the exhaust, a pump 30 may be installed. The pump 30 is assumed to operate at least during the warm-up of the internal combustion engine 20.

A bypass passage LC for discharging the exhaust gas cooled by the exhaust cooler 26 to the exhaust passage LA without returning to the intake passage LD is branched from the exhaust recirculation passage LB downstream of the exhaust cooler 26. That is, the bypass passage LC branches from the exhaust gas recirculation passage LB on the downstream side of the exhaust gas flow of the exhaust cooler 26 and on the upstream side of the exhaust gas flow of the second flow path adjustment mechanism 44, and from the first flow path adjustment mechanism 40. Connected to the exhaust passage LA on the downstream side of the exhaust gas flow. In the present embodiment, the other end of the bypass passage LC is connected to a position P3 upstream of the muffler 24 on the exhaust passage LA.
In addition, a third flow path adjustment mechanism 44 that changes the flow path area of the bypass passage LC is provided in the bypass path LC downstream of the branch position P2 with the exhaust gas recirculation path LB.

The exhaust gas recirculation passage LB is provided with a pressure sensor 18 for detecting the pressure in the passage.
In the present embodiment, it is assumed that the pressure sensor 18 is provided downstream of the exhaust cooler 26 in the exhaust gas recirculation passage LB, but the installation position of the pressure sensor 18 is the internal combustion engine 20, the first flow path adjustment. Any location can be used as long as the pressure in the region R (shaded portion in FIG. 3) surrounded by the mechanism 40, the second flow path adjustment mechanism 42, and the third flow path adjustment mechanism 44 can be detected. For example, when the pressure sensor 18 is disposed in the exhaust gas recirculation passage LB downstream of the exhaust cooler 26 and upstream of the branch position P2, the heat damage from the exhaust gas is detected to detect the pressure of the exhaust gas cooled by the exhaust cooler 26. It is hard to receive.

  The internal combustion engine 20 is provided with a knock sensor 19 that detects knocking that occurs during high-load operation or the like. The knock sensor 19 detects knocking vibration of the internal combustion engine 20 with a piezoelectric element or the like. The knock sensor 19 is connected to an ECU 50 which will be described later. When the knock sensor 19 detects knocking, the ECU 50 performs ignition retard or the like in the internal combustion engine 20.

In addition, the internal combustion engine 20 is provided with a water jacket around the combustion chamber, and heat exchange is performed between the cooling medium circulating in the water jacket and the combustion chamber, thereby overheating the internal combustion engine 20 due to combustion. It is preventing.
The above-described exhaust cooler cooling path 28 communicates with a water jacket in the internal combustion engine 20 and introduces a cooling medium that has passed through the exhaust cooler 26 into the water jacket.
The exhaust cooler cooling path 28 is provided with a temperature sensor 16 for detecting the temperature of the cooling medium.

An engine cooling passage 34 is also communicated with the water jacket. The engine cooling path 34 connects the internal combustion engine 20 and the radiator 32, and the cooling medium that has taken away heat from the internal combustion engine 20 and has risen in temperature is cooled by the radiator 32 and returned to the internal combustion engine 20.
The engine cooling path 34 is provided with a pump 36 and a thermostat valve 38.
The pump 36 circulates the cooling medium in the engine cooling path 34.
The thermostat valve 38 is provided upstream of the radiator 32, and closes when the cooling medium is lower than a predetermined temperature (for example, 70 ° C., for example), that is, warm air, and prevents the cooling medium from entering the radiator 32. In this case, the cooling medium passes through the radiator bypass 34A and circulates without being cooled.
Further, when the cooling medium is equal to or higher than the predetermined temperature, that is, after the completion of warming, the thermostat valve 38 is opened and the cooling medium enters the radiator 32. In this case, the cooling medium is cooled by the radiator 32 and the temperature decreases.
As described above, both the engine cooling path 34 and the exhaust cooler cooling path 28 communicate with the water jacket of the internal combustion engine 20, and the cooling medium passing through each cooling path is mixed in the water jacket.

The first flow path adjustment mechanism 40 and the third flow path adjustment mechanism 44 are, for example, butterfly valves. When the valve body D rotates around the valve rod S in the range of 0 degrees to 90 degrees, The flow area of the adjustment target passage is adjusted.
FIG. 1 illustrates a state in which the first flow path adjustment mechanism 40 and the third flow path adjustment mechanism 44 have the minimum flow path areas of the respective adjustment target paths (flow path area = zero), that is, are fully closed. Show. At this time, the rotation angle of the valve body D is 0 degree. When the rotation angle of the valve body D reaches 90 degrees, the flow passage area of the passage is maximum (flow passage area≈piping cross-sectional area), that is, fully opened.

The second flow path adjustment mechanism 42 is, for example, a globe valve that is a general EGR valve structure.
The opening degree of the second flow path adjustment mechanism 42 is controlled based on the recirculation amount of exhaust gas (EGR gas amount) to the intake passage LD.
More specifically, the ECU 50 to be described later determines the load of the internal combustion engine 20, the rotational speed, the pressure in the region R, and the opening degree of the second flow path adjustment mechanism 42 (flow path area of the exhaust gas recirculation path LB, EGR gas amount). And an opening degree of the second flow path adjustment mechanism 42 is changed based on the EGR introduction map.
When the second flow path adjustment mechanism 42 is fully closed, the flow area of the exhaust gas recirculation passage LB is minimum (flow path area = zero), and the second flow path adjustment mechanism 42 is fully open. The exhaust gas recirculation passage LB has a maximum flow path area (flow path area≈piping cross-sectional area).

The first flow path adjustment mechanism 40, the second flow path adjustment mechanism 42, and the third flow path adjustment mechanism 44 are controlled to be opened and closed by an ECU 50 that controls the operating state of the internal combustion engine 20.
FIG. 2 is an explanatory diagram showing a functional configuration of the ECU 50.
An ECU (Engine Control Unit) 50 is an interface unit that interfaces with a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an EEPROM that holds various data in a rewritable manner, and peripheral circuits. And so on.
Connected to the ECU 50 are various sensors such as an accelerator pedal sensor 52 for detecting the accelerator operation amount of the driver, a wheel speed sensor 54 for detecting the rotational speed of each wheel of the vehicle, the temperature sensor 16 and the pressure sensor 18, and the knock sensor 19 described above. Has been.

In the present embodiment, ECU 50 controls the open / close state of each flow path adjustment mechanism as follows based on the temperature of the cooling medium and the operating state of internal combustion engine 20.
FIG. 3 is an explanatory diagram showing a state of the warm-up promotion system 10 during the warm-up operation of the internal combustion engine 20.
Since the temperature of the internal combustion engine 20 is low immediately after the start of the vehicle or the like, a warm-up operation that promotes warm-up of the internal combustion engine 20 is performed. The ECU 50 determines whether or not to perform the warm-up operation using the detection value of the temperature sensor 16. That is, when the detected value of the temperature sensor 16 is lower than the predetermined temperature, the ECU 50 sets the warm-up promoting system 10 in the following state.
In FIG. 3, it is assumed that no load is applied to the internal combustion engine 20 (for example, an idling state).
Further, since the thermostat valve 38 is closed during the warm-up operation, the cooling medium is not cooled by the radiator 32.

During the warm-up operation, the ECU 50 controls the exhaust passage LA, the exhaust recirculation passage LB, and the bypass passage LC by the first flow passage adjustment mechanism 40, the second flow passage adjustment mechanism 42, and the third flow passage adjustment mechanism 44. Each channel area is limited.
More specifically, for example, the rotation angle of the valve body D of the first flow path adjustment mechanism 40 is set to 0 degree to make the valve body D fully closed, and the third flow path adjustment mechanism 44 is changed to a rotation angle of the valve body D of 45, for example. And half open. That is, the third flow path adjustment mechanism 44 makes the flow path area of the bypass passage LC larger than the flow path area of the exhaust passage LA restricted by the first flow path adjustment mechanism 40.
Further, as described above, no load is applied to the internal combustion engine 20, and the second flow path adjustment mechanism 42 is in a fully closed state.

In this case, the entire amount of exhaust gas discharged from the internal combustion engine 20 is introduced into the exhaust gas recirculation passage LB and passes through the exhaust cooler 26. Further, the amount of exhaust gas discharged through the bypass passage LC to the outside of the vehicle is limited, and the internal combustion engine 20, the first flow path adjustment mechanism 40, the second flow path adjustment mechanism 42, and the third flow path adjustment mechanism. The pressure in the region R (shaded portion) surrounded by 44 increases, and the exhaust gas temperature in the region R increases. Further, the flow rate of the exhaust gas in the region R becomes slow, and the time for the exhaust gas to stay in the region R becomes long.
As a result, the amount of heat transferred from the exhaust gas to the cooling medium in the exhaust cooler 26 increases, and the temperature of the cooling medium is increased more rapidly than when the exhaust gas is simply introduced into the exhaust gas recirculation passage LB. You can make a chance.
In general, it is known that the performance of the catalyst 22 decreases at low temperatures. However, in the present embodiment, since the catalyst 22 is disposed in the region R, the temperature of the catalyst 22 can be increased in a short time. And the performance of the catalyst 22 can be exhibited efficiently.

FIG. 4 is an explanatory diagram showing a state when a load is applied to the internal combustion engine 20 during the warm-up operation.
When the accelerator pedal is depressed during the warm-up operation and a load is applied to the internal combustion engine 20, the amount of exhaust gas from the internal combustion engine 20 increases. For this reason, the pressure in the area | region R rises rather than the state where the load shown in FIG. 3 is not given.
The second flow path adjustment mechanism 42 is opened according to the EGR introduction map described above, and a part of the exhaust gas is recirculated to the intake passage LD via the exhaust recirculation passage LB.

When the pressure in the region R detected by the pressure sensor 18 exceeds a predetermined pressure, the ECU 50 first increases the opening of the third flow path adjustment mechanism 44 as shown in FIG. Enlarge the channel area. As a result, the amount of exhaust gas discharged outside the vehicle via the bypass passage LC increases and the pressure in the region R decreases. At this time, the opening degree of the third flow path adjustment mechanism 44 is increased until the pressure in the region R becomes less than a predetermined pressure.
In addition, when the amount of exhaust gas from the internal combustion engine 20 is large or the like, the region R remains above the predetermined pressure even after the third flow path adjustment mechanism 44 is fully opened to maximize the flow path area of the bypass passage LC. As shown in FIG. 4B, the ECU 50 increases the opening degree of the first flow path adjustment mechanism 40 to increase the flow area of the exhaust passage LA. Thereby, the amount of exhaust gas introduced into the exhaust gas recirculation passage LB is reduced, and the pressure in the region R is reduced.
By doing in this way, while preventing the piping from being damaged due to the pressure increase in the region R, the heat transfer from the exhaust gas to the cooling medium is promoted, and the internal combustion engine 20 is warmed up early. Can do.
As shown in FIG. 4A, the opening degree of only the third flow path adjustment mechanism 44 is first adjusted when the opening degree of the first flow path adjustment mechanism 40 is increased and introduced into the exhaust gas recirculation passage LB. This is because the amount of exhaust gas to be reduced is reduced, the amount of heat exchange in the exhaust cooler 26 is reduced, and the time required to complete warm-up is lengthened.

Further, when the temperature of the cooling medium becomes equal to or higher than the predetermined temperature and the warm-up is completed, the ECU 50 increases the opening degree of the first flow path adjustment mechanism 40 and is warming up (when the temperature of the cooling medium is lower than the predetermined temperature). ), The flow passage area of the exhaust passage LA is enlarged.
Thereby, the amount of exhaust gas introduced into the exhaust gas recirculation passage LB is reduced, the amount of heat transferred from the exhaust gas to the cooling medium in the exhaust cooler 26 is reduced, and overheating of the internal combustion engine 20 can be prevented.

As described above, according to the warm-up promotion system 10 according to the embodiment, the pressure in the region R including the exhaust cooler 26 is increased during the warm-up of the internal combustion engine 20, so that the exhaust gas in the region R As the temperature rises, the flow rate of the exhaust gas in this region R becomes slower. As a result, the amount of heat transferred from the exhaust gas to the cooling medium in the exhaust cooler 26 increases, and the temperature of the cooling medium is increased more rapidly than when the exhaust gas is simply introduced into the exhaust gas recirculation passage LB. It is advantageous in planning the machine.
Further, according to the warm-up promotion system 10, the flow passage area of the bypass passage LC is made larger than the flow passage area of the exhaust passage LA. Therefore, the amount of exhaust gas introduced from the exhaust recirculation passage LB to the bypass passage LC is smaller than the amount of exhaust gas introduced from the exhaust passage LA to the exhaust recirculation passage LB, and the pressure in the region R is reduced. This is advantageous for raising the temperature reliably.
Further, according to the warm-up promotion system 10, since the pressure is adjusted by each flow path adjustment mechanism when the pressure in the region R becomes too high, damage to the piping due to excessive pressure is prevented, and warm-up is promoted. This is advantageous in improving the durability of the system 10. Further, at this time, since the opening degree of the first flow path adjustment mechanism 40 is increased after the third flow path adjustment mechanism 44 is fully opened, the region without reducing the amount of exhaust gas introduced into the exhaust gas recirculation passage LB as much as possible. This is advantageous in adjusting the pressure in R and warming up the internal combustion engine 20 in a short time.
Further, according to the warm-up promotion system 10, when the temperature of the cooling medium becomes equal to or higher than a predetermined temperature, the amount of exhaust gas introduced into the exhaust gas recirculation passage LB is reduced, and heat exchange with the cooling medium in the exhaust cooler 26 is performed. Reduce the amount. For this reason, it is advantageous in preventing the internal combustion engine 20 from being overheated by the cooling medium and maintaining the internal combustion engine 20 at an appropriate temperature.

  DESCRIPTION OF SYMBOLS 10 ... Warm-up promotion system, 20 ... Internal combustion engine, 26 ... Exhaust cooler, 28 ... Exhaust cooler cooling path, 32 ... Radiator, 34 ... Engine cooling path, 40 ... First flow path adjustment mechanism , 42... 2nd flow path adjustment mechanism, 44... 3rd flow path adjustment mechanism, 50... ECU, 52... Accelerator pedal sensor, 54. ... exhaust gas recirculation passage, LC ... bypass passage.

Claims (4)

A first flow path adjustment mechanism for changing a flow path area of an exhaust passage for discharging exhaust gas discharged from the internal combustion engine to the outside of the vehicle;
A second flow path that changes the flow passage area of an exhaust recirculation passage that branches off from the exhaust passage upstream of the first flow path adjustment mechanism and returns the exhaust gas to the intake passage of the internal combustion engine. An adjustment mechanism;
A bypass passage branching from the exhaust gas recirculation passage upstream of the exhaust gas flow from the second flow path adjustment mechanism and connected to the exhaust gas flow path downstream of the first flow path adjustment mechanism; A third flow path adjustment mechanism for changing the flow path area;
An exhaust cooler that is provided on the exhaust gas recirculation passage upstream of the exhaust gas flow from a branch with the bypass passage and cools the exhaust gas with a cooling medium;
A cooling path that connects the exhaust cooler and the internal combustion engine and enables heat exchange between the cooling medium and the internal combustion engine,
When the temperature of the cooling medium is lower than a predetermined temperature, the first flow path adjustment mechanism, the second flow path adjustment mechanism, and the third flow path adjustment mechanism limit the flow area of each flow path. To
A warm-up promoting system for an internal combustion engine. The third flow path adjustment mechanism has a flow path area of the bypass passage larger than a flow path area of the exhaust passage restricted by the first flow path adjustment mechanism;
The warm-up promoting system for an internal combustion engine according to claim 1. The pressure in the exhaust passage upstream of the exhaust gas flow of the first flow path adjustment mechanism, the pressure in the exhaust gas recirculation passage upstream of the exhaust gas flow of the second flow rate adjustment mechanism, A pressure sensor for detecting any one of the pressure of the bypass passage on the upstream side of the exhaust gas flow of the third flow rate adjustment mechanism,
When the pressure is equal to or higher than a predetermined pressure, the third flow path adjustment mechanism expands the flow path area of the bypass passage,
When the inside of the region is not less than the predetermined pressure even after the flow passage area of the bypass passage is maximized, the first flow passage adjustment mechanism expands the flow passage area of the exhaust passage.
The warm-up promoting system for an internal combustion engine according to claim 1 or 2. When the temperature of the cooling medium is equal to or higher than the predetermined temperature,
The first flow path adjustment mechanism increases the flow path area of the exhaust passage than when the temperature of the cooling medium is lower than the predetermined temperature;
The warm-up promoting system for an internal combustion engine according to any one of claims 1 to 3.

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