JP2021148074A - Humidity control device and humidity control method - Google Patents

Abstract

To provide a humidity control device and humidity control method capable of reliably suppressing influence of blow-by gas on humidity.SOLUTION: A humidity control device comprises: an adjustment valve 13 that is arranged in an exhaust pipe 3 extending from an exhaust port P2 of a vehicle engine 1, and adjusts the opening degree of the exhaust pipe 3; a humidity information acquisition unit 10 that acquires the humidity of blow-by gas G3 generated in engine 1; and a control unit 12 that controls the adjustment valve 13 so as to open the opening degree of the exhaust pipe 3 when the humidity of the blow-by gas G3 acquired by the humidity information acquisition unit 10 reaches a predetermined threshold value H while the opening degree of the exhaust pipe 3 is narrowed by the adjustment valve 13.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a humidity control device and a humidity control method.

In a vehicle engine, a combustion gas in a combustion chamber, an unburned mixture, or the like may leak into the crankcase from, for example, a gap between a piston and a cylinder to generate blow-by gas. This blow-by gas is discharged from the inside of the crankcase to the outside or returned to the intake side of the engine, for example. At this time, if the amount of water contained in the blow-by gas is large, it may affect the engine or the like.

Therefore, as a technique for suppressing the influence of humidity of blow-by gas, for example, Patent Document 1 discloses a control method for an internal combustion engine that suppresses the accumulation of ice generated at the confluence of new intake air and blow-by gas. There is. Since this internal combustion engine control method controls the internal combustion engine so that the temperature of the blow-by gas rises based on the temperature of the intake air sucked from the intake pipe, the blow-by gas freezes and ice accumulates even in a low temperature environment. Can be suppressed.

Japanese Unexamined Patent Publication No. 2014-101775

However, since the method of Patent Document 1 does not control the humidity of the blow-by gas itself, it is difficult to reliably suppress the influence of the humidity of the blow-by gas.

It is an object of the present disclosure to provide a humidity control device and a humidity control method that reliably suppress the influence of humidity of blow-by gas.

The humidity control device according to the present disclosure is arranged in an exhaust pipe extending from the exhaust port of the engine of the vehicle, and includes an adjustment valve for adjusting the opening degree of the exhaust pipe and a humidity information acquisition unit for acquiring the humidity of blow-by gas generated in the engine. , When the humidity of the blow-by gas acquired by the humidity information acquisition unit reaches a predetermined threshold while the opening of the exhaust pipe is narrowed by the adjusting valve, the adjustment valve is opened so that the opening of the exhaust pipe is opened. It is provided with a control unit for controlling.

The humidity control method according to the present disclosure includes a step of adjusting the opening degree of the exhaust pipe with an adjustment valve arranged in the exhaust pipe extending from the exhaust port of the engine of the vehicle, and a humidity information acquisition unit for adjusting the humidity of the blow-by gas generated in the engine. When the acquisition step and the humidity of the blow-by gas acquired by the humidity information acquisition unit reaches a predetermined threshold while the opening of the exhaust pipe is narrowed by the adjustment valve, the control unit opens the exhaust pipe. It includes a step of controlling the adjustment valve to open the degree.

According to the present disclosure, it is possible to reliably suppress the influence of humidity of blow-by gas.

It is a figure which shows the structure of the vehicle provided with the humidity control device which concerns on Embodiment 1 of this disclosure. It is a graph which shows the change of the humidity of blow-by gas. It is a figure which shows the main part of the humidity control apparatus which concerns on Embodiment 2.

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

FIG. 1 shows the configuration of a vehicle provided with the humidity control device according to the first embodiment of the present disclosure. The vehicle has an engine 1, an intake pipe 2, an exhaust pipe 3, a gas passage 4, and a humidity control device 5. Examples of vehicles include commercial vehicles such as trucks.

The engine 1 has a piston 1a, an injector 1b, an intake valve 1c, and an exhaust valve 1d. Examples of the engine 1 include a diesel engine of a four-stroke engine.

The piston 1a is arranged so as to reciprocate in the engine 1. A combustion chamber C1 and a crank chamber C2 are formed in the engine 1 with the piston 1a interposed therebetween. Further, the engine 1 is formed with an intake port P1 and an exhaust port P2 for opening the combustion chamber C1, respectively.

The injector 1b injects fuel into the combustion chamber C1 and is arranged so as to face the piston 1a.
The intake valve 1c is arranged at the intake port P1 and opens and closes the intake port P1 according to the movement of the piston 1a.
The exhaust valve 1d is arranged at the exhaust port P2 and opens and closes the exhaust port P2 according to the movement of the piston 1a.

The intake pipe 2 guides the intake G1 to the intake port P1 of the engine 1 and is arranged so as to extend to the intake port P1 via the compressor 7a of the air cleaner 6 and the turbocharger 7.
The exhaust pipe 3 guides the exhaust gas G2 discharged from the exhaust port P2 of the engine 1 to the outside, and is arranged so as to extend via the turbine 7b of the turbocharger 7.

The gas passage 4 is an open type that discharges blow-by gas G3 existing in the crankcase C2 of the engine 1 to the outside, and the base end portion is connected to the crankcase of the engine 1 and the tip portion is opened to the outside. There is. Further, an oil separator 8 for separating oil from the blow-by gas G3 is arranged in the gas passage 4.
In the blow-by gas G3, the combustion gas in the combustion chamber C1 and the unburned air-fuel mixture leak into the crank chamber C2 from the gap between the piston 1a and the cylinder.

The humidity control device 5 includes a humidity sensor 9, a humidity information acquisition unit 10, an aperture information acquisition unit 11, a control unit 12, and an adjustment valve 13. The humidity sensor 9 is connected to the humidity information acquisition unit 10, and the humidity information acquisition unit 10 is connected to the adjustment valve 13 via the control unit 12. Further, the aperture information acquisition unit 11 is connected to the control unit 12.

The adjusting valve 13 adjusts the opening degree of the exhaust pipe 3 and is arranged in the exhaust pipe 3 on the downstream side of the turbocharger 7 with respect to the flow direction of the exhaust gas G2. The adjusting valve 13 can be composed of, for example, a butterfly valve formed in a size corresponding to an exhaust passage in the exhaust pipe 3, and rotates around a rotation axis orthogonal to the exhaust pipe 3 to cause the exhaust pipe 3 to rotate. Adjust the opening of.

Here, the adjusting valve 13 is used to reduce the opening degree of the exhaust pipe 3 to increase the pressure during the regeneration process of the diesel particulate filter in the exhaust pipe 3 and the heating control of the vehicle such as the warm-up operation of the engine 1. It consists of an exhaust throttle valve provided.

The humidity sensor 9 detects the humidity of the blow-by gas G3 generated in the engine 1 and is arranged in the gas passage 4.
The humidity information acquisition unit 10 acquires the humidity detected by the humidity sensor 9.

The throttle information acquisition unit 11 is connected to, for example, an operation control unit (not shown), and is used to control the heating of the vehicle such as the regeneration process of the diesel particulate filter and the warm-up operation of the engine 1, and the timing of reducing the opening degree of the exhaust pipe 3. Acquires aperture information indicating.

The control unit 12 determines whether or not to reduce the opening degree of the exhaust pipe 3 based on the throttle information acquired by the throttle information acquisition unit 11, and if it is determined to reduce the opening degree of the exhaust pipe 3, exhausts the gas. The adjusting valve 13 is controlled so as to reduce the opening degree of the pipe 3. Further, when the humidity of the blow-by gas acquired by the humidity information acquisition unit 10 reaches a predetermined threshold value when the opening degree of the exhaust pipe 3 is narrowed by the adjustment valve 13, the control unit 12 determines the exhaust pipe 3 The adjustment valve 13 is controlled so as to open the opening degree of.

Next, the humidity control method of the present embodiment will be described.

First, as shown in FIG. 1, the throttle information acquisition unit 11 determines the timing at which the opening degree of the exhaust pipe 3 is throttled in the vehicle heating control such as the regeneration processing of the diesel particulate filter and the warm-up operation of the engine 1. Acquires the indicated aperture information. Here, as the aperture information of the regeneration process of the diesel particulate filter, the traveling time of the vehicle and the like can be mentioned. Further, as the throttle information of the warm-up operation, the temperature and the rotation speed of the cooling water of the engine 1 can be mentioned. The aperture information acquisition unit 11 outputs the acquired aperture information to the control unit 12.

Subsequently, the control unit 12 determines whether or not to reduce the opening degree of the exhaust pipe 3 based on the throttle information input from the throttle information acquisition unit 11.

The control unit 12 calculates the amount of fine particles collected by the diesel particulate filter based on, for example, the traveling time of the vehicle acquired by the aperture information acquisition unit 11, and collects a predetermined amount of fine particles. If so, the adjustment valve 13 is controlled so as to reduce the opening degree of the exhaust pipe 3.
As a result, the temperature inside the exhaust pipe 3 rises to the temperature at which the regeneration process is performed, and the fine particles collected by the diesel particulate filter can be burned and removed.

Further, the control unit 12 determines whether or not to carry out the warm-up operation based on, for example, the temperature and the rotation speed of the cooling water of the engine 1 acquired by the throttle information acquisition unit 11. The control unit 12 controls the adjusting valve 13 so as to narrow the opening degree of the exhaust pipe 3 when the warm-up operation is performed.
As a result, the load on the engine 1 is increased, and the temperature of each part of the engine 1 can be rapidly increased.

When the opening degree of the exhaust pipe 3 is narrowed by the adjusting valve 13 in this way, the above heating control is possible, but the humidity of the blow-by gas G3 generated in the engine 1 may increase.

Generally, the blow-by gas G3 is generated when the combustion gas or the like in the combustion chamber C1 of the engine 1 leaks from between the piston 1a and the cylinder or the like into the crankcase C2 of the crankcase. At this time, when the combustion gas is burned in the combustion chamber C1, water is generated, so that the water caused by this combustion is contained in the blow-by gas G3. Here, when the opening degree of the exhaust pipe 3 is not throttled by the adjusting valve 13, the moisture generated in the combustion chamber C1 sequentially flows through the exhaust pipe 3 and is discharged to the outside, so that the blow-by gas G3 Humidity is kept low to some extent.

On the other hand, when the opening degree of the exhaust pipe 3 is narrowed by the adjusting valve 13, the pressure of the exhaust passage Pa extending from the engine 1 to the adjusting valve 13 in the exhaust pipe 3 rises, and the combustion chamber communicating with the exhaust passage Pa increases. The pressure of C1 also rises. Therefore, the moisture generated in the combustion chamber C1 is not smoothly discharged from the combustion chamber C1 to the exhaust passage Pa, but stays in the combustion chamber C1, and the moisture discharged to the exhaust passage Pa also returns to the combustion chamber C1. , The humidity of the combustion chamber C1 rises. Then, as the humidity of the combustion chamber C1 rises, the humidity of the blow-by gas G3 also rises.
Further, since the pressure difference between the combustion chamber C1 and the crank chamber C2 is larger than that in the case where the opening degree of the exhaust pipe 3 is not narrowed down, the blow-by gas G3 leaking from the combustion chamber C1 to the crank chamber C2. Will also increase.
That is, when the opening degree of the exhaust pipe 3 is narrowed by the adjusting valve 13, a large amount of high humidity blow-by gas G3 is generated.

This high-humidity blow-by gas G3 flows into the gas passage 4 from the crank chamber C2, and after the oil is separated by the oil separator 8, it is discharged to the outside through the opening. At this time, if the humidity of the blow-by gas G3 exceeds a predetermined threshold value, the water content may condense and white smoke may be generated due to the temperature difference between the crank chamber C2 and the external environment. Further, since a large amount of blow-by gas G3 is discharged to the outside from the gas passage 4, the amount of white smoke also increases. If the blow-by gas G3 is discharged from the gas passage 4 to the vicinity of the engine 1, for example, white smoke will be generated around the engine 1, and it may be erroneously recognized that a problem such as a failure has occurred in the vehicle. There is.

Therefore, when the control valve 13 controls the adjusting valve 13 so as to narrow the opening degree of the exhaust pipe 3, the control unit 12 sequentially acquires the humidity of the blow-by gas G3 from the humidity information acquisition unit 10. Specifically, the humidity of the blow-by gas G3 in the gas passage 4 is detected by the humidity sensor 9, and the humidity is input to the control unit 12 via the humidity information acquisition unit 10.

As shown in FIG. 2, when the opening degree of the exhaust pipe 3 is narrowed down at time T0, the humidity of the blow-by gas G3 gradually increases with the passage of time. When the humidity of the blow-by gas G3 detected by the humidity sensor 9 is equal to or less than a preset threshold value H, the control unit 12 narrows the opening degree of the exhaust pipe 3 without changing the posture of the adjusting valve 13. Maintain the state. For example, the threshold value H can be set based on the amount of white smoke (the amount of condensed water) with respect to the humidity of the blow-by gas G3.

Then, when the humidity of the blow-by gas G3 detected by the humidity sensor 9 reaches the threshold value H at the time T1, the control unit 12 controls the adjusting valve 13 so as to open the opening degree of the exhaust pipe 3. As a result, the moisture in the combustion chamber C1 of the engine 1 sequentially flows through the exhaust pipe 3 and is discharged to the outside, so that the humidity of the blow-by gas G3 is gradually lowered and the white smoke discharged to the outside from the gas passage 4 The amount of gas can be suppressed.

At this time, it is preferable that the control unit 12 sets the threshold value H based on the external temperature. That is, the control unit 12 can set the threshold value H to be smaller as the external temperature decreases.
Further, it is preferable that the control unit 12 sets the threshold value H based on the pressure of the exhaust passage Pa of the exhaust pipe 3. That is, the control unit 12 can set the threshold value H to be smaller as the pressure in the exhaust passage Pa is higher.
As a result, the control unit 12 can surely suppress the generation of white smoke.

Further, when the humidity of the blow-by gas G3 acquired by the humidity information acquisition unit 10 decreases by a predetermined value S from the threshold value H, the control unit 12 adjusts the adjustment valve 13 so as to narrow the opening degree of the exhaust pipe 3 again. It is preferable to control. In this way, the control unit 12 repeatedly adjusts the opening degree of the exhaust pipe 3 with the adjusting valve 13 based on the threshold value H, thereby controlling the heating of the vehicle such as the regeneration processing of the diesel particulate filter and the warm-up operation. It is possible to suppress the generation of white smoke while maintaining the above.

Further, the adjusting valve 13 is not limited to the one that adjusts the opening degree of the exhaust pipe 3 between the open state in which the exhaust pipe 3 is opened and the throttle state in which almost all of the exhaust pipe 3 is throttled. For example, the adjusting valve 13 can be adjusted so that the opening degree of the exhaust pipe 3 is throttled in a plurality of stages. As a result, the control unit 12 can adjust the opening degree of the exhaust pipe 3 stepwise based on the threshold value H.

According to the present embodiment, the humidity of the blow-by gas G3 acquired by the humidity information acquisition unit 10 reaches a predetermined threshold value H when the control unit 12 narrows the opening degree of the exhaust pipe 3 by the adjustment valve 13. If so, the adjustment valve 13 is controlled so as to open the opening degree of the exhaust pipe 3. As a result, the amount of white smoke discharged to the outside from the gas passage 4 can be reduced, and the influence of the humidity of the blow-by gas G3 can be reliably suppressed.

In the present embodiment, the humidity sensor 9 is arranged between the oil separator 8 and the engine 1 in the gas passage 4, but can also be arranged on the tip side of the oil separator 8 in the gas passage 4.
Further, in the present embodiment, the humidity sensor 9 is arranged in the gas passage 4, but the humidity sensor 9 is not limited to this as long as it can detect the humidity of the blow-by gas G3. For example, the humidity sensor 9 can be arranged in the crankcase of the engine 1 to detect the humidity of the crank chamber C2.

(Embodiment 2)
Hereinafter, the second embodiment of the present disclosure will be described. Here, the differences from the above-described first embodiment will be mainly described, and the common reference numerals will be used for the common points with the above-described first embodiment, and detailed description thereof will be omitted.

In the first embodiment described above, the control unit 12 controls the adjusting valve 13 based on the preset threshold value H, but calculates the threshold value H based on the saturated water vapor amount in the external environment, and calculates the calculated threshold value. The adjustment valve 13 can also be controlled based on H.
For example, as shown in FIG. 3, the temperature sensor 21 can be newly arranged in the intake pipe 2 of the first embodiment.

The temperature sensor 21 is arranged on the upstream side of the air cleaner 6 in the distribution direction of the intake air G1 flowing through the intake pipe 2, and detects the temperature of the intake air G1 flowing into the intake pipe 2, that is, the temperature of the external environment.

The humidity information acquisition unit 10 is connected to the temperature sensor 21 and calculates the saturated water vapor amount in the external environment based on the temperature detected by the temperature sensor 21.

The control unit 12 calculates the threshold value H based on the saturated water vapor amount acquired by the humidity information acquisition unit 10. Then, when the humidity of the blow-by gas detected by the humidity sensor 9 reaches the threshold value H when the opening degree of the exhaust pipe 3 is narrowed by the adjusting valve 13, the control unit 12 opens the exhaust pipe 3. The adjusting valve 13 is controlled so as to open.

With such a configuration, the temperature sensor 21 detects the temperature of the external environment, and the humidity information acquisition unit 10 calculates the saturated water vapor amount of the external environment based on the temperature detected by the temperature sensor 21. Then, the humidity information acquisition unit 10 outputs the calculated saturated water vapor amount to the control unit 12. Further, the humidity information acquisition unit 10 outputs the humidity of the blow-by gas G3 detected by the humidity sensor 9 to the control unit 12 as in the first embodiment.

Subsequently, when the control unit 12 determines whether or not to reduce the opening degree of the exhaust pipe 3 based on the throttle information input from the throttle information acquisition unit 11, and determines that the opening degree of the exhaust pipe 3 is reduced. The adjustment valve 13 is controlled so as to reduce the opening degree of the exhaust pipe 3.

At this time, the control unit 12 calculates the threshold value H based on the saturated water vapor amount of the external environment acquired by the humidity information acquisition unit 10. The control unit 12 can set the threshold value H for the saturated water vapor amount in the external environment, for example.
Subsequently, the control unit 12 calculates the amount of water vapor contained in the blow-by gas G3 based on the humidity of the blow-by gas G3 detected by the humidity sensor 9. At this time, if the amount of water vapor in the blow-by gas G3 exceeds the threshold value H, the water contained in the blow-by gas G3 may condense and white smoke may be generated. Therefore, the control unit 12 controls the adjusting valve 13 so as to open the opening degree of the exhaust pipe 3 when the amount of water vapor contained in the blow-by gas G3 reaches the threshold value H.

As a result, the control unit 12 can surely reduce the amount of white smoke discharged to the outside from the gas passage 4.
The control unit 12 can also calculate the humidity at which the condensation of water occurs in the external environment based on the saturated water vapor amount in the external environment, and set this humidity to the threshold value H. As a result, the control unit 12 can control the adjusting valve 13 so as to open the opening degree of the exhaust pipe 3 when the humidity of the blow-by gas G3 detected by the humidity sensor 9 reaches the threshold value H.

According to the present embodiment, since the control unit 12 calculates a predetermined threshold value H based on the saturated water vapor amount acquired by the humidity information acquisition unit 10, the humidity of the blow-by gas G3 is highly accurate according to the external environment. The amount of white smoke discharged to the outside from the gas passage 4 can be reduced more reliably.
Although the temperature sensor 21 is arranged in the intake pipe 2, it is not limited to the intake pipe 2 as long as it can detect the temperature of the external environment.

(Embodiment 3)
Hereinafter, embodiments 1 and 2 of the present disclosure will be described. Here, the differences from the above-described first and second embodiments will be mainly described, and the common points with the above-described first and second embodiments will be described in detail by using a common reference code. Omit.

In the above-described first and second embodiments, the humidity information acquisition unit 10 detects and acquires the humidity of the blow-by gas G3 with the humidity sensor 9, but it is estimated based on the moisture state of the intake air and the exhaust gas of the engine 1. It is also possible to obtain the humidity of the blow-by gas G3.

For example, the humidity information acquisition unit 10 blow-by based on the moisture concentration of the exhaust recirculation gas, the moisture concentration of the intake air, and the fuel combustion moisture concentration obtained by dividing the moisture amount generated by the combustion of the fuel by the exhaust flow rate. The humidity of the gas G3 can be estimated.

Here, the water contained in the blow-by gas G3 can be regarded as a combination of the water derived from the intake air, the water derived from the fuel, and the water derived from the exhaust gas recirculation gas. Therefore, the water content Wby of the blow-by gas G3 can be calculated by the following formula (1). The exhaust gas recirculation gas is a gas in which a part of the exhaust gas in the exhaust pipe 3 is allowed to flow through the intake pipe 2.

Wbby = (γ x Wesh / Ge + (1-γ) x Wa / Ga + α x Wcomb / Ge) x Qbby x ρ x 60/1000 ... (1)

Here, the first term (γ × Next / Ge) in parentheses represents the water concentration of the exhaust gas recirculation gas introduced into the cylinder of the engine 1. Note that γ is an exhaust gas recirculation rate, and can be calculated based on, for example, the engine speed and the target fuel injection amount. Wesh is the water content of the exhaust gas, and can be calculated based on, for example, the intake water content and the fuel combustion water content. Ge is the flow rate of the exhaust gas.

The second term ((1-γ) × Wa / Ga) in parentheses represents the water concentration of the intake air G1 introduced into the cylinder of the engine 1. Wa is the amount of intake water, and can be calculated based on the intake flow rate, air humidity, and air density ρ. Ga is the intake flow rate.

Further, (Wcomb / Ge) in the third term in parentheses represents the concentration of the water content of the exhaust gas generated by the combustion of the fuel, and is obtained by dividing the fuel combustion water content Wcomb by the flow rate Ge of the exhaust gas. .. Wcomb is the amount of fuel combustion water, and can be calculated based on, for example, the amount of water produced with respect to the fuel and the fuel flow rate.

The water content Wbby of the blow-by gas G3 can be estimated by summing the values obtained by multiplying each of these concentrations by the flow rate Qbby of the blow-by gas G3. At this time, the water concentration of the exhaust gas recirculation gas and the intake G1 is uniform, while the water concentration of the fuel decreases from the center of the cylinder toward the outside, and blow-by gas G3 is formed in the portion where the water concentration is low. NS. In order to reflect this non-uniformity of water concentration, in the formula (1), a predetermined water mixing rate α (0 <α <1) set in advance based on a test or the like is multiplied.

According to the present embodiment, since the humidity information acquisition unit 10 estimates the humidity of the blow-by gas G3 based on the moisture state of the engine 1, the humidity of the blow-by gas G3 is acquired without arranging the humidity sensor 9 or the like. be able to.

In the above-described first to third embodiments, the gas passage 4 is formed in an open type that discharges the blow-by gas G3 to the outside, but is formed in a closed type that allows the blow-by gas G3 to flow through the intake pipe 2. You can also. If the blow-by gas G3 having a high humidity is permeated into the intake pipe 2 through the gas passage 4, for example, the blow-by gas G3 may be frozen. Therefore, the control unit 12 controls the adjusting valve 13 so as to open the opening degree of the exhaust pipe 3, so that the influence of the humidity of the blow-by gas G3 can be reliably suppressed.

Further, in the above-described first to third embodiments, the adjusting valve 13 is composed of the exhaust throttle valve, but it is not limited to the exhaust throttle valve as long as it adjusts the opening degree of the exhaust pipe 3. ..

In addition, the above embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. be. That is, the present invention can be implemented in various forms without departing from its gist or its main features. For example, the disclosure of the shape, number, and the like of each part described in the above embodiment is merely an example, and can be appropriately modified and implemented.

The humidity control device according to the present disclosure can be used as a device for narrowing the opening degree of the exhaust pipe with an adjusting valve.

1 Engine 1a Piston 1b Injector 1c Intake valve 1d Exhaust valve 2 Intake pipe 3 Exhaust pipe 4 Gas passage 5 Humidity control device 6 Air cleaner 7 Turbocharger 8 Oil separator 9 Humidity sensor 10 Humidity information acquisition unit 11 Squeeze information acquisition unit 12 Control unit 13 Adjustment valve 21 Temperature sensor C1 Combustion chamber C2 Crank chamber G1 Intake G2 Exhaust gas G3 Blow-by gas H threshold P1 Intake port P2 Exhaust port Pa Exhaust path S Predetermined value T0, T1 time

Claims (8)

An adjustment valve that is placed in the exhaust pipe that extends from the exhaust port of the engine of the vehicle and adjusts the opening degree of the exhaust pipe,
Humidity information acquisition unit that acquires the humidity of blow-by gas generated in the engine,
When the humidity of the blow-by gas acquired by the humidity information acquisition unit reaches a predetermined threshold value while the opening degree of the exhaust pipe is narrowed by the adjusting valve, the opening degree of the exhaust pipe is opened. A humidity control device including a control unit that controls the adjustment valve. The control unit controls the adjustment valve so as to reduce the opening degree of the exhaust pipe again when the humidity of the blow-by gas acquired by the humidity information acquisition unit decreases from the predetermined threshold value. The humidity control device according to 1. The humidity information acquisition unit further acquires the saturated water vapor amount in the external environment, and further acquires the saturated water vapor amount.
The humidity control device according to claim 1 or 2, wherein the control unit calculates the predetermined threshold value based on the saturated water vapor amount acquired by the humidity information acquisition unit. It also has a temperature sensor that detects the temperature of the external environment,
The humidity control device according to claim 3, wherein the humidity information acquisition unit acquires the saturated water vapor amount based on the temperature detected by the temperature sensor. Further having a humidity sensor located in the crankcase of the engine or a gas passage connected to the crankcase to detect humidity.
The humidity control device according to any one of claims 1 to 4, wherein the humidity information acquisition unit acquires the humidity detected by the humidity sensor. The humidity control device according to any one of claims 1 to 4, wherein the humidity information acquisition unit acquires the humidity of blow-by gas estimated based on the moisture state of the engine. The humidity control device according to any one of claims 1 to 6, wherein the adjusting valve is composed of an exhaust throttle valve. A step of adjusting the opening degree of the exhaust pipe with an adjustment valve arranged in the exhaust pipe extending from the exhaust port of the engine of the vehicle, and
The step of acquiring the humidity of blow-by gas generated in the engine by the humidity information acquisition unit, and
When the humidity of the blow-by gas acquired by the humidity information acquisition unit reaches a predetermined threshold value while the opening degree of the exhaust pipe is narrowed by the adjustment valve, the control unit opens the exhaust pipe. A humidity control method comprising controlling the adjustment valve to open the degree.

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