WO2020050291A1

WO2020050291A1 - Compressor protection device

Info

Publication number: WO2020050291A1
Application number: PCT/JP2019/034697
Authority: WO
Inventors: 伊織倉田; 学五百住
Original assignee: いすゞ自動車株式会社
Priority date: 2018-09-06
Filing date: 2019-09-04
Publication date: 2020-03-12
Also published as: JP2020041427A

Abstract

A compressor protection device comprising an exhaust air recirculation passage 35, a valve 37 provided in the exhaust air recirculation passage 35, an accelerator position sensor 39, a turbo rotation speed sensor 40, and an electronic control unit 100 for controlling the valve 37 on the basis of detection values from the accelerator position sensor 39 and the turbo rotation speed sensor 40. The electronic control unit 100 determines, on the basis of the detection values from the accelerator position sensor 39 and the turbo rotation speed sensor 40, whether condensation water has struck compressor fins of a compressor 14C, and closes the valve 37 when it is determined that condensation water has struck the compressor fins.

Description

Compressor protection device

The present disclosure relates to a compressor protection device that protects a compressor from collision with condensed water.

がある Some internal combustion engines include a turbocharger and an exhaust gas recirculation device.

高圧 High-pressure EGR devices and low-pressure EGR devices are generally known as exhaust gas recirculation devices (hereinafter, referred to as “EGR devices”).

The high-pressure EGR device returns the exhaust gas on the upstream side of the turbine to the intake passage on the downstream side of the compressor.

The low pressure EGR device returns the exhaust gas on the downstream side of the turbine to the intake passage on the upstream side of the compressor.

Japanese Patent Application Laid-Open No. 2016-094909 Japanese Patent Application Laid-Open No. 2015-036526 Japanese Patent Application Laid-Open No. 2009-209816 Japanese Patent Application Publication No. 2016-070078

In the low-pressure EGR device, the exhaust gas downstream of the turbine whose temperature has become relatively low is returned to the intake passage upstream of the compressor. For this reason, condensed water may be generated in the low-pressure EGR device. The condensed water may enter the compressor housing from the low-pressure EGR passage via the intake passage and collide with the rotating compressor fin.

コンプレッサ If the condensed water collides with the rotating compressor fin, the compressor fin may be damaged.

Accordingly, the present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a compressor protection device that can prevent a compressor from continuing to collide with condensed water.

According to one aspect of the present disclosure,
An exhaust recirculation passage for returning exhaust gas from an exhaust passage downstream of the turbine of the turbocharger to an intake passage upstream of the compressor;
A valve provided in the exhaust gas recirculation passage;
An accelerator opening sensor for detecting the opening of the accelerator,
A turbo speed sensor for detecting the speed of the turbocharger,
An electronic control unit that controls the valve based on the detection values of the accelerator opening sensor and the turbo speed sensor,
The electronic control unit determines whether or not condensed water collides with the compressor fins of the compressor based on the detection values of the accelerator opening sensor and the turbo speed sensor, and the condensed water collides with the compressor fins. When it is determined that the valve is closed, the valve is closed.

Preferably, when the difference between the differential value of the detection value of the accelerator opening sensor and the differential value of the detection value of the turbo speed sensor is equal to or greater than a preset threshold value, It is determined that the condensed water has collided with the compressor fin.

Preferably, the valve is provided in the exhaust gas recirculation passage downstream of the cooler, a temperature sensor is provided in the exhaust gas recirculation passage between the cooler and the valve, and the electronic control unit includes: When the detected value of the temperature sensor becomes equal to or higher than a preset temperature, the valve is opened.

Preferably, the valve is provided in the exhaust gas recirculation passage downstream of the cooler, a temperature sensor is provided in the exhaust gas recirculation passage between the cooler and the valve, and the electronic control unit includes: The valve is opened when a detection value of the temperature sensor becomes equal to or higher than a preset temperature and when a preset time elapses after the detection value of the temperature sensor becomes equal to or higher than the preset temperature.

According to the above aspect, it is possible to prevent the compressor from continuously colliding with the condensed water.

FIG. 1 is a schematic explanatory diagram of an internal combustion engine according to an embodiment of the present disclosure. FIG. 2 is a diagram showing the relationship between the turbo rotation speed and the accelerator opening. FIG. 3 is a diagram showing a relationship between a turbo rotation speed and an accelerator opening when condensed water hits a compressor fin. FIG. 4 is an enlarged explanatory view of a main part of FIG. FIG. 5 is a flowchart of a routine for starting protection of the compressor. FIG. 6 is a flowchart of a routine for ending the protection of the compressor. FIG. 7 is a flowchart showing a modification of FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory diagram of an internal combustion engine (engine) 1 according to the present disclosure. The engine 1 is a multi-cylinder compression ignition type internal combustion engine mounted on a vehicle, that is, a diesel engine. Although the illustrated example shows an in-line four-cylinder engine, the cylinder arrangement type and the number of cylinders of the engine are arbitrary.

The engine 1 includes an engine body 2, an intake passage 3 and an exhaust passage 4 connected to the engine body 2, and a fuel injection device 5. The engine body 2 includes structural parts such as a cylinder head, a cylinder block, and a crankcase, and movable parts housed therein, such as a piston, a crankshaft, and a valve.

The fuel injection device 5 is a common rail type fuel injection device, and includes a fuel injection valve or injector 7 provided in each cylinder, and a common rail 8 connected to the injector 7. The injector 7 directly injects fuel into the cylinder 9. The common rail 8 stores fuel injected from the injector 7 in a high pressure state.

The intake passage 3 is mainly defined by an intake manifold 10 connected to the engine body 2 (particularly, a cylinder head) and an intake pipe 11 connected to an upstream end of the intake manifold 10. The intake manifold 10 distributes and supplies the intake air sent from the intake pipe 11 to the intake ports of each cylinder. In the intake pipe 11, an air cleaner 12, an air flow meter 13, a compressor 14C of a turbocharger 14, an intercooler 15, and an electronically controlled intake throttle valve 16 are provided in this order from the upstream side. The air flow meter 13 is a sensor (intake air amount sensor) for detecting the amount of intake air (intake air flow) per unit time of the engine 1.

The exhaust passage 4 is mainly defined by an exhaust manifold 20 connected to the engine body 2 (particularly, the cylinder head) and an exhaust pipe 21 arranged downstream of the exhaust manifold 20. The exhaust manifold 20 collects the exhaust gas sent from the exhaust port of each cylinder. A turbine 14T of the turbocharger 14 is provided between the exhaust pipe 21 or between the exhaust manifold 20 and the exhaust pipe 21. An oxidation catalyst 22, a particulate filter (Diesel Particulate Filter) 23, a NOx catalyst 24, and an ammonia oxidation catalyst 26 are provided in the exhaust pipe 21 downstream of the turbine 14T in order from the upstream side. The arrangement of the oxidation catalyst 22, the DPF 23, the NOx catalyst 24, and the ammonia oxidation catalyst 26 is not limited to this. Further, the oxidation catalyst 22, the DPF 23, the NOx catalyst 24, and the ammonia oxidation catalyst 26 may be replaced with another exhaust gas purification device, and may be omitted if unnecessary.

The oxidation catalyst 22 oxidizes and purifies unburned components (hydrocarbon HC and carbon monoxide CO) in the exhaust gas, heats and raises the temperature of the exhaust gas by the reaction heat at this time, and removes NO in the exhaust gas. Oxidizes to NO2. The DPF 23 is formed of a so-called continuous regeneration type DPF with a catalyst, and captures particulate matter (PM) contained in exhaust gas and continuously burns and removes the captured PM. The NOx catalyst 24 is composed of a selective reduction type NOx catalyst (SCR), and reduces NOx in exhaust gas using ammonia caused by urea water added from an addition valve (not shown) as a reducing agent. The ammonia oxidation catalyst 26 oxidizes and purifies excess ammonia discharged from the NOx catalyst 24.

The engine 1 also includes a high-pressure exhaust gas recirculation device (hereinafter, referred to as “high-pressure EGR device”) 30 and a low-pressure exhaust gas recirculation device (hereinafter, referred to as “low-pressure EGR device”) 34.

The high-pressure EGR device 30 and the low-pressure EGR device 34 return the exhaust gas in the exhaust passage 4 to the intake passage 3.

The high-pressure EGR device 30 includes a high-pressure EGR passage 31, a high-pressure EGR cooler 32, and a high-pressure EGR valve 33. The high pressure EGR passage 31 connects the intake manifold 10 and the exhaust manifold 20. The high-pressure EGR cooler 32 is provided in the high-pressure EGR passage 31. The high-pressure EGR valve 33 is provided in the high-pressure EGR passage 31 downstream of the high-pressure EGR cooler 32.

The low pressure EGR device 34 includes a low pressure EGR passage (exhaust gas recirculation passage) 35, a low pressure EGR cooler 36, and a low pressure EGR valve 37. The low pressure EGR cooler 36 corresponds to a “cooler” in the claims. The low pressure EGR valve 37 corresponds to a “valve” in the claims.

The low pressure EGR passage 35 connects the exhaust passage 4 between the DPF 23 and the NOx catalyst 24 and the intake passage 3 upstream of the compressor 14C. The low-pressure EGR passage 35 may be connected to the exhaust passage 4 at any position as long as the exhaust passage 4 is located downstream of the turbine 14T. However, when the low pressure EGR passage 35 is connected to the exhaust passage 4 downstream of the DPF 23, clean exhaust gas from which PM has been removed can be recirculated to the intake side.

The low pressure EGR cooler 36 is provided in the low pressure EGR passage 35. The low pressure EGR valve 37 is provided in the low pressure EGR passage 35 downstream of the low pressure EGR cooler 36.

In the engine 1, the outlet end of the low-pressure EGR passage 35 is connected to a position upstream of the compressor 14C in the intake passage 3. In this case, the condensed water generated in the low-pressure EGR cooler 36 and the low-pressure EGR passage 35 may flow into the intake passage 3 together with the exhaust gas.

In this case, the condensed water may collide with the compressor fins as water droplets to deform or break the compressor fins.

Therefore, in the present embodiment, a compressor protection device 38 for protecting the compressor fin from collision with condensed water is provided.

The compressor protection device 38 includes a low-pressure EGR passage 35, a low-pressure EGR cooler 36, a low-pressure EGR valve 37, an accelerator opening sensor 39, a turbo speed sensor 40, and an electronic control unit (hereinafter, referred to as “ECU”) 100. And

The ECU 100 forms a control unit or a controller. The ECU 100 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like. The ECU 100 controls the injector 7, the intake throttle valve 16, the high-pressure EGR valve 33, and the low-pressure EGR valve 37.

The accelerator opening sensor 39 detects the accelerator opening. The accelerator opening sensor 39 is electrically connected to the ECU 100, and outputs accelerator opening information to the ECU 100 as an electric signal.

The turbo speed sensor 40 detects the speed of the compressor and the turbine. The turbo speed sensor 40 is electrically connected to the ECU 100 and outputs turbo speed information to the ECU 100 as an electric signal.

(4) The ECU 100 is electrically connected to a low-pressure EGR cooler outlet temperature sensor 41 for detecting an exhaust gas temperature between the low-pressure EGR cooler 36 and the low-pressure EGR valve 37. The low pressure EGR cooler outlet temperature sensor 41 outputs temperature information to the ECU 100 as an electric signal.

{Circle around (4)} The ECU 100 determines whether or not the condensed water has collided with the compressor fin based on the detection values of the accelerator opening sensor 39 and the turbo speed sensor 40.

FIG. 2 is a graph showing the relationship between the turbo rotation speed R (rpm) and the accelerator opening AC (%). FIG. 3 is a diagram showing a relationship between the turbo rotation speed R (rpm) and the accelerator opening AC (%) when the condensed water hits the compressor fin. In the figure, the turbo speed R is indicated by a solid line, and the accelerator opening AC is indicated by a broken line.

とき As shown in FIG. 2, when condensed water does not collide with the compressor fin, the turbo rotation speed changes substantially following the change in the accelerator opening. At this time, the change in the turbo speed is delayed by a certain time with respect to the change in the accelerator opening. For this reason, the differential value of the turbo rotation speed becomes substantially the same as the differential value of the accelerator opening before the predetermined time.

(3) However, as shown in FIG. 3, when condensed water collides with the compressor fin, the turbo speed instantaneously decreases irrespective of the accelerator opening. Therefore, it is possible to determine whether or not the condensed water has collided with the compressor fin by comparing the differential value of the accelerator opening with the differential value of the turbo speed.

The ECU 100 according to the present embodiment determines whether or not condensed water has collided with the compressor fin using the above-described principle. When the ECU 100 determines that the condensed water has collided with the compressor fin, the ECU 100 closes the low-pressure EGR valve 37. Thereby, it is possible to prevent the condensed water from continuously colliding with the compressor fin, and to protect the compressor fin from the condensed water.

Next, a control routine according to the present embodiment will be described with reference to FIGS. FIG. 5 shows a control routine for starting protection of the compressor fins (hereinafter referred to as “protection start routine”). FIG. 6 shows a control routine for terminating the protection of the compressor fins (hereinafter referred to as a “protection termination routine”).

(4) The protection start routine and the protection end routine are repeatedly executed by the ECU 100 every predetermined calculation period τ.

The calculation cycle τ is set in units of time. The calculation cycle τ is, for example, 1 millisecond (msec), and the ECU 100 executes a protection start routine and a protection end routine every 1 millisecond.

Note that the change in the turbo rotation speed is delayed for a fixed time with respect to the change in the accelerator opening, but for convenience of explanation, it is assumed that there is no delay. That is, when the ECU 100 compares the differential value of the turbo rotation speed with the differential value of the accelerator opening, the ECU 100 uses the differential value of the accelerator opening before the certain time. However, description of such a point is omitted. The ECU 100 stores the differential value of the accelerator opening before the predetermined time. The certain time can be calculated by an arbitrary method, for example, from a map set in advance based on the engine operating state.

First, the protection start routine shown in FIG. 5 will be described.

In step S101, the ECU 100 detects the turbo rotation speed R (rpm) using the turbo rotation speed sensor 40.

In step S102, the ECU 100 calculates a differential value ΔR of the turbo rotation speed R. At this time, the ECU 100 stores the turbo rotation speed R detected when the protection start routine was executed last time. The ECU 100 calculates the differential value ΔR of the turbo rotation speed R by dividing the difference between the turbo rotation speed R1 detected last time and the turbo rotation speed R2 detected this time by the calculation cycle τ.

That is, the ECU 100 calculates ΔR = (R2−R1) / τ.

Note that the turbo rotation speed R1 detected last time, that is, one time before, may be replaced with the turbo rotation speed R1 detected N times before (N is an integer of 2 or more). At this time, when calculating the differential value ΔR, Nτ is used instead of τ. However, the differential value ΔR may be calculated without dividing by τ or Nτ.

In step S103, the ECU 100 detects the accelerator opening AC using the accelerator opening sensor 39.

In step S104, the ECU 100 calculates a differential value ΔAC of the accelerator opening AC. At this time, the ECU stores the accelerator opening AC detected when the protection start routine was executed last time. The ECU 100 calculates a differential value ΔAC of the accelerator opening AC by dividing the difference between the accelerator opening AC1 detected last time and the accelerator opening AC2 detected this time by the calculation cycle τ.

That is, the ECU 100 calculates ΔAC = (AC2−AC1) / τ.

Note that, similarly to the case of the turbo rotation speed R, the accelerator opening AC1 detected last time, that is, one time before, may be replaced with the accelerator opening AC1 ′ detected N times before (N is an integer of 2 or more). Good. At this time, when calculating the differential value ΔAC, Nτ is used instead of τ. However, the differential value ΔAC may be calculated without dividing by τ or Nτ.

In step S105, the ECU 100 calculates the absolute value A of the difference between the differential value ΔR of the turbo rotation speed R and the differential value ΔAC of the accelerator opening AC.

Specifically, the ECU 100 calculates A = | (ΔR × C) −ΔAC |. C in the formula is a conversion coefficient for making the unit and size of the differential value ΔR of the turbo rotation speed R correspond to the unit and size of the differential value ΔAC of the accelerator opening AC so that the two can be easily compared, It is determined in advance by experiments, simulations, and the like.

In step S106, the ECU 100 determines whether or not the absolute value A of the difference between the differential value ΔAC and the differential value ΔR is equal to or greater than a preset threshold value. Here, the threshold value is a value obtained by previously performing a difference between a differential value ΔR of the turbo rotation speed R and a differential value ΔAC of the accelerator opening AC when condensed water hits the compressor fins by experiment, simulation, or the like. It is.

For example, when the accelerator opening AC tends to increase in a state where condensed water is not generated in the low-pressure EGR cooler 36, the turbo rotation speed R also tends to increase. For this reason, the absolute value A of the difference between the differential value ΔAC and the differential value ΔR becomes a small value and becomes smaller than the threshold value.

On the other hand, when condensed water hits the compressor fins when the accelerator opening AC tends to increase, as shown in FIG. 4, the differential value ΔAC of the accelerator opening AC becomes a positive value, while The differential value ΔR of the rotation speed R is a negative value. Therefore, the absolute value A of the difference between the differential value ΔAC and the differential value ΔR becomes a large value and is equal to or larger than the threshold value.

For this reason, when the absolute value A of the difference between the differential value ΔAC and the differential value ΔR is equal to or larger than the threshold value (A ≧ threshold value), the ECU 100 determines that the condensed water has hit the compressor fin, and proceeds to step Proceed to S107. If the absolute value A of the difference between the differential value ΔAC and the differential value ΔR is smaller than the threshold value (A <threshold value), the ECU 100 determines that no condensed water is generated, and proceeds to step S109. The protection start routine ends.

In step S107, the ECU 100 closes (fully closes) the low-pressure EGR valve 37.

In step S108, the ECU 100 locks the low-pressure EGR valve 37 in a closed state. Thus, the low pressure EGR valve 37 cannot be opened by another control until the lock is released. For example, a flag may be used to lock the low-pressure EGR valve 37. Further, the flag may be configured by a global variable whose value is maintained even after the protection start routine ends. Another routine executed by the ECU 100 may determine the locked state of the low-pressure EGR valve 37 according to the value of the flag when trying to open the low-pressure EGR valve 37. Specifically, another routine executed by the ECU 100 may be programmed so as not to open the low-pressure EGR valve 37 when the flag is set (for example, 1 is substituted for the flag).

Next, the protection termination routine shown in FIG. 6 will be described.

In step S201, the ECU 100 determines whether the low-pressure EGR valve 37 is locked. If the low-pressure EGR valve 37 is locked, the process proceeds to step S202. If the low-pressure EGR valve 37 is not locked, the process proceeds to step S205, and the protection end routine ends.

In step S202, the ECU 100 detects the exhaust gas temperature T between the low pressure EGR cooler 36 and the low pressure EGR valve 37 using the low pressure EGR cooler outlet temperature sensor 41.

In step S203, the ECU 100 determines whether the exhaust gas temperature T is equal to or higher than a preset temperature. Here, the set temperature is a temperature at which the condensed water accumulated in the low-pressure EGR passage 35 between the low-pressure EGR cooler 36 and the low-pressure EGR valve 37 is almost entirely vaporized, and is determined in advance by experiments, simulations, and the like.

When the exhaust gas temperature T is equal to or higher than the set temperature (exhaust gas temperature T ≧ set temperature), the ECU 100 determines that the condensed water accumulated in the low-pressure EGR passage 35 has been vaporized, and proceeds to step S204. When the exhaust gas temperature T is lower than the set temperature (exhaust gas temperature T <set temperature), the ECU 100 determines that the condensed water accumulated in the low-pressure EGR passage 35 has not been vaporized, and proceeds to step S205. End the protection end routine.

In step S204, the ECU 100 unlocks the low-pressure EGR valve 37. Thus, the low pressure EGR valve 37 is opened by another control. For example, when a flag is used to lock the low-pressure EGR valve 37, the lock of the low-pressure EGR valve 37 may be released by lowering the flag (for example, substituting 0 for the flag).

Although the embodiments of the present disclosure have been described above in detail, the present disclosure is also capable of the following other embodiments.

FIG. 7 is a flowchart showing a modification of the protection end routine. The same processes as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

In the protection end routine shown in FIG. 6, when the ECU 100 determines whether or not the condensed water accumulated in the low-pressure EGR passage 35 has been vaporized, only the step S203 (whether or not the exhaust gas temperature T has become equal to or higher than the set temperature) is performed. Was determined.

However, as shown in FIG. 7, the ECU 100 according to the modified example is set in advance after the exhaust gas temperature T is equal to or higher than the set temperature (Step S203: Yes) and the detection value of the temperature sensor is equal to or higher than the set temperature. When the set time has elapsed (steps S203a and S203b: Yes), it may be determined that the condensed water accumulated in the low-pressure EGR passage 35 has been vaporized. The set time in step S203b is a time required for the condensed water to evaporate, and is determined in advance by experiments, simulations, or the like. According to this, the set temperature in step S203 of FIG. 7 can be set lower than the set temperature in step S203 of FIG. 6, and the lock of the low-pressure EGR valve 37 may be released at an earlier timing.

In the modification shown in FIG. 7, in step S203, if the exhaust gas temperature T is equal to or higher than the set temperature (exhaust gas temperature T ≧ set temperature), the ECU 100 advances the process to step S203a. If the exhaust gas temperature T is lower than the set temperature (exhaust gas temperature T <set temperature), the ECU 100 advances the process to step S205 and ends the protection end routine.

In step 203a, the ECU 100 starts measuring time.

In step 203b, the ECU 100 determines whether or not the time at which the measurement was started in step 203a has exceeded the set time. If the set time has not elapsed (No), the ECU 100 returns the process to step S203b, and repeats the process of step S203b. If the set time has elapsed (Yes), the ECU 100 proceeds with the process to step S204.

In step S204, the ECU 100 unlocks the low-pressure EGR valve 37.

実施 The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the spirit of the present disclosure defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be construed as limiting, but can be applied to any other technology belonging to the scope of the idea of the present disclosure.

This application is based on Japanese Patent Application (No. 2018-166849) filed on Sep. 6, 2018, the contents of which are incorporated herein by reference.

According to the present disclosure, it is possible to prevent the compressor from continuously colliding with the condensed water, and it is useful in that the risk of breakage of the compressor fin can be reduced.

DESCRIPTION OF SYMBOLS 1 Engine 2 Engine main body 3 Intake passage 4 Exhaust passage 5 Fuel injection device 7 Injector 8 Common rail 9 Cylinder 10 Intake manifold 11 Intake pipe 12 Air cleaner 13 Air flow meter 14 Turbocharger 14C Compressor 14T Turbine 15 Intercooler 16 Intake throttle valve 20 Exhaust manifold 21 Exhaust pipe 22 Oxidation catalyst 23 Particulate filter 24 NOx catalyst 26 Ammonia oxidation catalyst 30 High pressure EGR device 31 High pressure EGR passage 32 High pressure EGR cooler 33 High pressure EGR valve 34 Low pressure EGR device 35 Low pressure EGR passage (exhaust recirculation passage)
36 Low pressure EGR cooler (cooler)
37 Low pressure EGR valve (valve)
38 Compressor protection device 39 Accelerator opening sensor 40 Turbo speed sensor 41 Low pressure EGR cooler outlet temperature sensor 100 Electronic control unit

Claims

An exhaust recirculation passage for returning exhaust gas from an exhaust passage downstream of the turbine of the turbocharger to an intake passage upstream of the compressor;
A valve provided in the exhaust gas recirculation passage;
An accelerator opening sensor for detecting the opening of the accelerator,
A turbo speed sensor for detecting the speed of the turbocharger,
An electronic control unit that controls the valve based on the detection values of the accelerator opening sensor and the turbo speed sensor,
The electronic control unit determines whether or not condensed water collides with the compressor fins of the compressor based on the detection values of the accelerator opening sensor and the turbo speed sensor, and the condensed water collides with the compressor fins. Closing the valve when it is determined.
The electronic control unit, when a difference between the differential value of the detection value of the accelerator opening sensor and the differential value of the detection value of the turbo speed sensor is equal to or greater than a predetermined threshold, the electronic control unit may The compressor protection device according to claim 1, wherein it is determined that the condensed water has collided.
The valve is provided in the exhaust gas recirculation passage downstream of the cooler,
A temperature sensor is provided in the exhaust gas recirculation passage between the cooler and the valve,
The compressor protection device according to claim 1, wherein the electronic control unit opens the valve when a detection value of the temperature sensor becomes equal to or higher than a preset temperature.
The valve is provided in the exhaust gas recirculation passage downstream of the cooler,
A temperature sensor is provided in the exhaust gas recirculation passage between the cooler and the valve,
The electronic control unit, when the detection value of the temperature sensor is equal to or higher than a predetermined set temperature, and when a predetermined set time has elapsed since the detection value of the temperature sensor is equal to or higher than the set temperature The compressor protection device according to claim 1, wherein the valve is opened.