WO2022065145A1 - Piston temperature estimation device and piston temperature estimation method - Google Patents

Piston temperature estimation device and piston temperature estimation method Download PDF

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Publication number
WO2022065145A1
WO2022065145A1 PCT/JP2021/033844 JP2021033844W WO2022065145A1 WO 2022065145 A1 WO2022065145 A1 WO 2022065145A1 JP 2021033844 W JP2021033844 W JP 2021033844W WO 2022065145 A1 WO2022065145 A1 WO 2022065145A1
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Prior art keywords
temperature
piston
estimation
estimated
exhaust brake
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PCT/JP2021/033844
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French (fr)
Japanese (ja)
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拓朗 三田
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いすゞ自動車株式会社
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Publication of WO2022065145A1 publication Critical patent/WO2022065145A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/04—Introducing corrections for particular operating conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D45/00—Electrical control not provided for in groups F02D41/00 - F02D43/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/04—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning exhaust conduits
    • F02D9/06—Exhaust brakes

Definitions

  • the present disclosure relates to a piston temperature estimation device and a piston temperature estimation method.
  • Patent Documents 1 and 2 Conventionally, a method of estimating the temperature of the piston of an internal combustion engine is known (see, for example, Patent Documents 1 and 2).
  • the air filling rate kl based on the amount of air taken in from the vacuum sensor, the engine rotation speed Ne, and the cooling water temperature from the water temperature sensor.
  • the tentative estimated temperature of the top surface of the piston is calculated using the air flow rate Ga based on Tw, the amount of intake air from the vacuum sensor, and the temperature of the intake air from the temperature sensor of the air cleaner. Then, the estimated temperature of the top surface of the piston is calculated by subjecting the tentative estimated temperature of the top surface of the piston to a smoothing process using the air flow rate Ga.
  • the temperature of the piston is calculated based on the heat transfer coefficient of, the temperature of the engine oil, the heat transfer coefficient between the piston and the injected fuel, and the temperature of the injected fuel.
  • Patent Documents 1 and 2 may not be able to properly estimate the temperature of the piston.
  • An object of the present disclosure is to provide a piston temperature estimation device and a piston temperature estimation method that can appropriately estimate the piston temperature.
  • the piston temperature estimation device includes a tentative estimation unit that calculates a tentative estimation value of the temperature of a piston constituting the internal combustion engine, a determination unit that determines whether or not the exhaust brake of the internal combustion engine is operating, and a determination unit.
  • the increase amount estimation unit that estimates the amount of increase in the temperature of the piston due to the operation of the exhaust brake, and the provisional estimation unit that calculates when the determination unit determines that the exhaust brake is operating.
  • the value obtained by adding the increase amount estimated by the increase amount estimation unit to the tentative estimation value is estimated as the temperature of the piston, and when it is determined by the determination unit that the exhaust brake is not operating, the tentative estimation is performed.
  • a unit is provided with an estimation unit that estimates the tentative estimated value calculated by the unit as the temperature of the piston.
  • the piston temperature estimation method includes a step of calculating a tentative estimation value of the temperature of a piston constituting the internal combustion engine, a step of determining whether or not the exhaust brake of the internal combustion engine is operating, and the exhaust brake.
  • the amount of increase in the temperature of the piston due to the operation of the exhaust brake is estimated, and the value obtained by adding the amount of increase to the provisional estimated value is estimated as the temperature of the piston. If it is determined that the exhaust brake is not operating, the step of estimating the tentative estimated value as the temperature of the piston is executed.
  • FIG. 1 A block diagram showing a configuration of a piston temperature estimation device according to an embodiment of the present disclosure.
  • a flowchart showing an example of the operation of the piston temperature estimation device according to the embodiment of the present disclosure.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of an engine.
  • the engine 10 shown in FIG. 1 is a diesel engine mounted on an automobile such as a truck.
  • the engine 10 includes a cylinder 20 and a piston 40.
  • the internal combustion engine of the present disclosure is not limited to a diesel engine, and may be a gasoline engine or the like.
  • An injector 22 is provided on the cylinder head 21 above the cylinder 20 so as to face the center of the top surface of the piston 40.
  • the cylinder head 21 is provided with an intake port 23 and an exhaust port 24 so as to be located on the left and right sides of the injector 22.
  • the intake port 23 and the exhaust port 24 are provided with an intake valve 25 and an exhaust valve 26, respectively.
  • An intake flow path 27 is connected to the intake port 23.
  • An exhaust flow path 28 is connected to the exhaust port 24.
  • the exhaust flow path 28 is provided with an exhaust brake valve 29.
  • the exhaust brake valve 29 is composed of a butterfly type exhaust brake valve.
  • the exhaust brake valve 29 is driven by the actuator 30 and is configured to be able to block the exhaust flow path 28.
  • the actuator 30 is driven when the driver turns on an operation switch (not shown) and takes his / her foot off the accelerator pedal. Then, when the exhaust flow path 28 is blocked by the exhaust brake valve 29, the exhaust brake is activated.
  • the specific conditions for operating the exhaust brake are not limited to the above conditions, and various conditions can be used. Further, when the driver turns off the operation switch, the actuator 30 is driven and the exhaust flow path 28 is opened by the exhaust brake valve 29, the operation of the exhaust brake is released.
  • the cylinder 20 is provided with a cooling passage (not shown).
  • the cylinder 20 is cooled by supplying cooling water to the cooling passage.
  • the piston 40 is installed so as to be able to reciprocate in the cylinder 20.
  • a cavity 42 is provided on the top surface of the piston upper portion 41 of the piston 40.
  • the skirt portion 43 of the piston 40 is provided with a pair of pin boss portions 44 facing each other (only one pin boss portion 44 is shown in FIG. 1).
  • the upper end of the connecting rod 46 is connected to the pin fitting holes of the pair of pin boss portions 44 via the piston pin 45.
  • the lower end of the connecting rod 46 is connected to the crankshaft 48 via the crankpin 47.
  • the crankshaft 48 converts the reciprocating motion of the piston 40 into a rotary motion.
  • the piston 40 is provided with a cooling channel (not shown). Cooling oil jetted from an oil jet (not shown) is supplied to the cooling channel to cool the piston 40.
  • FIG. 2 is a block diagram showing the configuration of the piston temperature estimation device.
  • FIG. 3 is a graph showing the relationship between the rotational speed of the crankshaft and the temperature of the piston in the state in which the exhaust brake is operated and in the state in which the exhaust brake is not operated.
  • FIG. 4 is a graph showing the relationship between the rotational speed of the crankshaft and the amount of increase in the temperature of the piston due to the operation of the exhaust brake.
  • the piston temperature estimation device 100 includes a calculation unit 110 and a storage unit 120.
  • the arithmetic unit 110 has, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like as hardware. Each function of the arithmetic unit 110 described below is realized by executing a computer program read from the ROM by the CPU on the RAM.
  • the calculation unit 110 includes an acquisition unit 111, a provisional estimation unit 112, a determination unit 113, an increase amount estimation unit 114, and an estimation unit 115.
  • the acquisition unit 111 acquires engine status information representing the engine status from various sensors.
  • the tentative estimation unit 112 tentatively estimates the temperature of the piston 40.
  • the temperature of the piston 40 estimated by the tentative estimation unit 112 may be referred to as a “tentative estimation value”.
  • the determination unit 113 determines whether or not the exhaust brake is operating.
  • the rise amount estimation unit 114 estimates the temperature rise amount of the piston 40 due to the operation of the exhaust brake based on the rise amount estimation formula stored in the storage unit 120.
  • the amount of temperature increase estimated by the increase amount estimation unit 114 may be referred to as "estimated amount of increase”.
  • the estimation unit 115 estimates the temperature of the piston 40 based on the provisional estimated value and the estimated increase amount.
  • the temperature of the piston 40 estimated by the estimation unit 115 may be referred to as an “estimated temperature”.
  • the estimation unit 115 selects a predetermined time constant from a plurality of time constants stored in the storage unit 120, and corrects the estimated temperature using the selected time constant.
  • the estimated temperature of the piston 40 corrected by using the time constant may be referred to as “corrected estimated temperature”.
  • the storage unit 120 stores the temperature provisional estimation map.
  • the temperature provisional estimation map is a map showing the relationship between the rotation speed of the crankshaft 48 per unit time (hereinafter, may be referred to as "engine rotation speed"), the fuel injection amount, and the estimated temperature of the piston 40. ..
  • the temperature tentative estimation map is used for estimating the tentative estimated value in the tentative estimation unit 112.
  • the storage unit 120 stores the increase amount estimation formula represented by the following formula (1).
  • the increase amount estimation formula is an example of information for increase amount estimation.
  • the increase amount estimation formula is used for estimating the estimated increase amount in the increase amount estimation unit 114.
  • the information for estimating the amount of increase may be in a map format such as a temperature provisional estimation map.
  • dT ⁇ 1 ⁇ E + ⁇ 1 ... (1)
  • dT Estimated amount of increase ⁇ 1, ⁇ 1 : Coefficient E: Engine speed
  • the increase amount estimation formula is obtained, for example, as follows.
  • the relationship between the engine rotation speed and the temperature of the piston 40 when fuel is not injected and the exhaust brake is not operating is obtained.
  • the horizontal axis is the engine rotation speed and the vertical axis is the temperature of the piston 40
  • the temperature of the piston 40 increases as the engine rotation speed increases, as shown by the triangle marks in FIG.
  • the relationship between the engine rotation speed and the temperature of the piston 40 in a state where fuel is not injected and the exhaust brake is operating is obtained.
  • the horizontal axis is the engine rotation speed and the vertical axis is the temperature of the piston 40
  • the temperature of the piston 40 increases as the engine rotation speed increases, as shown by a square mark in FIG.
  • the ratio of the temperature rise of the piston 40 to the engine rotation speed is larger than that in the state where the exhaust brake is not operating. This is because when the exhaust brake is activated, the pumping loss of the internal combustion engine increases and the temperature of the working gas in the combustion chamber 11 surrounded by the piston 40, the cylinder 20 and the cylinder head 21 rises, and a part of the exhaust gas is discharged. It is considered that the backflow into the combustion chamber 11 and the high working gas temperature are maintained, so that the amount of heat supplied to the piston 40 increases, and as a result, the temperature of the piston 40 rises.
  • the temperature of the piston 40 used for creating the rise amount estimation formula may be a value obtained by simulation or an actually measured value.
  • the storage unit 120 has a first time constant, a second time constant, a third time constant, a fourth time constant, a fifth time constant, a sixth time constant, a seventh time constant, and an eighth time constant. Memorize the time constant.
  • the first to eighth time constants indicate the degree of change rate of the temperature of the piston 40.
  • the first to eighth time constants are used to calculate the corrected estimated temperature in the estimation unit 115.
  • the first to fourth time constants are selected when the cooling oil is not injected into the piston 40.
  • the first time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 has stopped.
  • the second time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 is running.
  • the value of the first time constant is larger than the value of the second time constant.
  • the third time constant is selected when the temperature of the piston 40 has dropped and fuel injection is being performed.
  • the change in the temperature of the piston 40 is large with respect to the change in the fuel injection amount, and the rate of decrease in the temperature of the piston 40 is the fuel injection. Equivalent or faster than if not done. Therefore, the value of the third time constant is smaller than the value of the first time constant, and is equal to or smaller than the value of the second time constant.
  • the fourth time constant is selected when the temperature of the piston 40 is rising.
  • the value of the fourth time constant is larger than the value of the third time constant.
  • the fifth to eighth time constants are selected in a state where the cooling oil is injected into the piston 40.
  • the fifth time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 has stopped.
  • the temperature of the piston 40 drops faster than when the cooling oil is not injected into the piston 40. Therefore, the value of the fifth time constant is smaller than the value of the first time constant.
  • the sixth time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 is running.
  • the temperature of the piston 40 drops faster than when the cooling oil is not injected into the piston 40. Therefore, the value of the sixth time constant is smaller than the value of the second time constant.
  • the seventh time constant is selected when the temperature of the piston 40 has dropped and fuel injection is being performed.
  • the temperature of the piston 40 drops faster than when the cooling oil is not injected into the piston 40. Therefore, the value of the seventh time constant is smaller than the value of the third time constant.
  • the eighth time constant is selected when the temperature of the piston 40 is rising.
  • the temperature rise rate of the piston 40 is faster than that in the case where the cooling oil is not injected into the piston 40. Therefore, the value of the eighth time constant is smaller than the value of the fourth time constant.
  • the acquisition unit 111 includes engine rotation speed, fuel injection amount to the combustion chamber 11 of the engine 10, fuel injection timing, fuel injection pressure, presence / absence of injection of cooling oil to the piston 40, and cooling oil. Hydraulic pressure, oil temperature of cooling oil, intake air temperature, intake pressure, intake air amount, intake air temperature, cooling water temperature of cylinder 20, operation signal of exhaust brake based on operation of operation switch, exhaust temperature, EGR (Exhaust Gas Recirculation) ) Obtain the gas flow rate, etc.
  • the tentative estimation unit 112 estimates the temperature of the piston 40 based on the engine rotation speed and the fuel injection amount acquired by the acquisition unit 111 and the temperature tentative estimation map stored in the storage unit 120.
  • the tentative estimation unit 112 corrects the temperature estimated based on the temperature tentative estimation map or the like using the information such as the fuel injection timing acquired by the acquisition unit 111, and estimates the corrected value as the tentative estimation value.
  • the determination unit 113 determines whether or not the exhaust brake is operating based on the engine state information acquired by the acquisition unit 111.
  • Estimating unit 115 When the determination unit 113 determines that the exhaust brake is operating, the estimation unit 115 adds the estimated increase amount calculated by the increase amount estimation unit 114 to the provisional estimation value calculated by the provisional estimation unit 112. The value is calculated as the estimated temperature of the piston 40. When the determination unit 113 determines that the exhaust brake is not operating, the estimation unit 115 estimates the tentative estimation value calculated by the tentative estimation unit 112 as the estimated temperature of the piston 40.
  • the estimated temperature of the piston 40 and the actual temperature may differ depending on the state of the engine 10. In particular, in a situation where the state of the engine 10 changes transiently, the difference between the estimated temperature and the actual temperature is remarkable. Then, depending on the state of the engine 10, the time constant indicating the degree of change in the estimated temperature changes.
  • the estimation unit 115 further corrects the estimated temperature by using the time constant corresponding to the state of the engine 10, and calculates the corrected estimated temperature.
  • the estimation unit 115 determines from among a plurality of time constants stored in the storage unit 120, based on the change state of the estimated temperature, the operating state of the engine 10, and the injection state of the cooling oil to the piston 40. Select the time constant of. The estimation unit 115 corrects the estimated temperature based on the selected predetermined time constant.
  • the estimation unit 115 divides the difference value between the newly estimated estimated temperature and the estimated temperature estimated one cycle before by a predetermined time constant, and adds the value obtained by dividing the difference value to the estimated temperature one cycle before, so that the estimated temperature is estimated. To correct. Thereby, the estimated temperature can be corrected to correspond to the speed of change in the temperature of the actual piston 40.
  • the estimation unit 115 selects a relatively small time constant. As a result, the corrected estimated temperature is greatly affected by the newly estimated estimated temperature.
  • the estimation unit 115 selects a relatively large time constant. As a result, the corrected estimated temperature is greatly affected by the estimated temperature estimated in the past.
  • the estimation unit 115 calculates the corrected estimated temperature T PSC using, for example, the following equation (2).
  • the formula for calculating the corrected estimated temperature is not limited to the formula (2).
  • T PSC T PSO + ⁇ ⁇ ( TPS-T PSO ) / ⁇ ⁇ ⁇ ⁇ (2)
  • T PSO Estimated temperature estimated one cycle before T PS : Estimated temperature newly estimated ⁇ : Predetermined value ⁇ : Time constant
  • FIG. 5 is a flowchart showing an example of the operation of the piston temperature estimation device.
  • the acquisition unit 111 of the piston temperature estimation device 100 acquires engine state information (step S1).
  • the tentative estimation unit 112 of the piston temperature estimation device 100 includes the engine rotation speed and the fuel injection amount included in the engine state information acquired by the acquisition unit 111, the temperature tentative estimation map stored in the storage unit 120, and the tentative estimation map.
  • a tentative estimate is calculated based on (step S2).
  • the determination unit 113 of the piston temperature estimation device 100 determines whether or not the exhaust brake is operating based on the information regarding the operation of the operation switch included in the engine state information acquired by the acquisition unit 111. Step S3).
  • the increase amount estimation unit 114 of the piston temperature estimation device 100 uses the increase amount estimation formula (formula (formula)) stored in the storage unit 120.
  • the estimated amount of increase is estimated based on 1)) and the engine rotation speed acquired by the acquisition unit 111 (step S4).
  • the estimation unit 115 of the piston temperature estimation device 100 calculates a value obtained by adding the estimated increase amount to the provisional estimated value as the estimated temperature of the piston 40 (step S5).
  • step S6 when the determination unit 113 determines that the exhaust brake is not operating (step S3: NO), the estimation unit 115 estimates the tentative estimated value as the estimated temperature of the piston 40 (step S6).
  • step S7 the estimation unit 115 determines the operating state of the engine 10 and the injection state of the cooling oil included in the engine state information acquired by the acquisition unit 111, and the change state of the estimated temperature. Based on this, a time constant is selected (step S7).
  • the estimation unit 115 calculates the correction estimated temperature based on the calculation formula (formula (2)), the time constant selected in step S7, and the estimated temperature (step S8).
  • the corrected estimated temperature calculated in step S8 is stored in the storage unit 120 and is used, for example, for predicting the life of the engine 10.
  • the estimated temperature T PSO estimated one cycle before the equation (2) does not exist.
  • the oil temperature, the temperature of the mouth of the cavity 42 calculated separately, or a preset value may be used as the estimated temperature T PSO .
  • the acquisition unit 111 determines whether or not to end the piston temperature estimation process (step S9).
  • step S9 determines that the piston temperature estimation process is to be terminated, for example, when the operation of the engine 10 is completed (step S9: YES), the acquisition unit 111 terminates the process. On the other hand, when the acquisition unit 111 determines that the piston temperature estimation process is not terminated (step S9: NO), the acquisition unit 111 performs the process of step S1.
  • the piston temperature estimation device 100 estimates a tentative estimation value of the temperature of the piston 40 based on the engine rotation speed, the fuel injection amount, and the tentative temperature estimation map.
  • the piston temperature estimation device 100 calculates an estimated increase in temperature of the piston 40 due to the operation of the exhaust brake, and adds a tentative estimated value to the estimated increase in the piston 40. Calculated as the estimated temperature of.
  • the piston temperature estimation device 100 estimates the tentative estimated value as the estimated temperature of the piston 40 when the exhaust brake is not operating. Therefore, the piston temperature estimation device 100 can calculate the estimated temperature by reflecting the temperature of the piston 40 that rises with the operation of the exhaust brake. Therefore, the piston temperature estimation device 100 can appropriately estimate the temperature of the piston 40. Then, for example, the life of the engine 10 can be accurately predicted based on the appropriately estimated temperature of the piston 40.
  • the piston temperature estimation device 100 calculates the estimated increase amount by substituting the engine rotation speed acquired by the acquisition unit 111 into the increase amount estimation formula. Therefore, the estimated increase amount can be calculated by a simple method of substituting the engine rotation speed into the increase amount estimation formula.
  • the piston temperature estimation device 100 calculates a corrected estimated temperature obtained by correcting the estimated temperature based on a time constant indicating the degree of change rate of the estimated temperature. Therefore, the temperature of the piston 40 at the time of estimation can be estimated more appropriately.
  • the calculation unit 110 corrects using a predetermined time constant selected from a plurality of time constants based on the change state of the temperature of the piston 40, the engine rotation speed, the fuel injection amount, and the injection state of the cooling oil. Calculate the estimated temperature. Therefore, the actual temperature of the piston 40 can be estimated accurately.
  • a quadratic polynomial (indicated by a alternate long and short dash line) of the data shown by the circles in FIG. 4 as shown in the following formula (3) may be used.
  • a cubic polynomial or a quaternary polynomial may be used instead of the above formula (1).
  • the first to eighth time constants were used properly, but it is not limited to this.
  • the time constant may be further subdivided based on the change state of the temperature of the piston 40, the engine operating state, and the injection state of the cooling oil. Other parameters may be taken into consideration when subdividing the time constant.
  • estimation unit 115 It is not necessary to provide the estimation unit 115 with a function for correcting the estimated temperature.
  • the configuration of the present disclosure can be applied to the piston temperature estimation device and the piston temperature estimation method.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

This piston temperature estimation device comprises: a preliminary estimation unit which calculates a preliminary estimated value of the temperature of a piston that constitutes an internal combustion engine; a determination unit which determines whether or not an exhaust brake of the internal combustion engine is being activated; a rise amount estimation unit which estimates an amount of temperature rise in the piston, the rise resulting from the activation of the exhaust brake; and an estimation unit which estimates, as the temperature of the piston, a value obtained by adding the rise amount estimated by the rise amount estimation unit to the preliminary estimated value calculated by the preliminary estimation unit in the case when the determination unit has determined that the exhaust brake is being activated, and which meanwhile estimates, as the temperature of the piston, the preliminary estimated value calculated by the preliminary estimation unit in the case when the determination unit has determined that the exhaust brake is not being activated.

Description

ピストン温度推定装置およびピストン温度推定方法Piston temperature estimation device and piston temperature estimation method
　本開示は、ピストン温度推定装置およびピストン温度推定方法に関する。 The present disclosure relates to a piston temperature estimation device and a piston temperature estimation method.
　従来、内燃機関のピストンの温度を推定する方法が知られている（例えば、特許文献１，２参照）。 Conventionally, a method of estimating the temperature of the piston of an internal combustion engine is known (see, for example, Patent Documents 1 and 2).
　特許文献１に記載の方法では、最初のエンジンの始動から所定時間経過しているときに、バキュームセンサからの吸入空気量に基づく空気充填率ｋｌ、エンジン回転速度Ｎｅ、水温センサからの冷却水温度Ｔｗ、バキュームセンサからの吸入空気量とエアクリーナの温度センサからの吸入空気温度とに基づく空気流量Ｇａを用いて、ピストンの頂面の仮推定温度を計算する。そして、ピストンの頂面の仮推定温度に、空気流量Ｇａを用いたなまし処理を施すことによって、ピストンの頂面の推定温度を計算する。 In the method described in Patent Document 1, when a predetermined time has elapsed from the start of the first engine, the air filling rate kl based on the amount of air taken in from the vacuum sensor, the engine rotation speed Ne, and the cooling water temperature from the water temperature sensor. The tentative estimated temperature of the top surface of the piston is calculated using the air flow rate Ga based on Tw, the amount of intake air from the vacuum sensor, and the temperature of the intake air from the temperature sensor of the air cleaner. Then, the estimated temperature of the top surface of the piston is calculated by subjecting the tentative estimated temperature of the top surface of the piston to a smoothing process using the air flow rate Ga.
　特許文献２に記載の方法では、燃焼室ガスとピストンとの間の熱伝達係数、燃焼室ガスの温度、ピストンとシリンダとの間の熱伝達係数、シリンダ壁温、ピストンとエンジンオイルとの間の熱伝達係数、エンジンオイルの温度、ピストンと噴射燃料との間の熱伝達係数、噴射燃料の温度に基づいて、ピストンの温度を算出する。 In the method described in Patent Document 2, the heat transfer coefficient between the combustion chamber gas and the piston, the temperature of the combustion chamber gas, the heat transfer coefficient between the piston and the cylinder, the cylinder wall temperature, and between the piston and the engine oil. The temperature of the piston is calculated based on the heat transfer coefficient of, the temperature of the engine oil, the heat transfer coefficient between the piston and the injected fuel, and the temperature of the injected fuel.
日本国特開２００５－２７３５３０号公報Japanese Patent Application Laid-Open No. 2005-273530 日本国特開２００７－２７８０９６号公報Japanese Patent Application Laid-Open No. 2007-278906
　しかしながら、排気ブレーキが搭載されている自動車において、排気ブレーキが作動した場合、特許文献１，２に記載の方法では、ピストンの温度を適切に推定できないおそれがある。 However, in an automobile equipped with an exhaust brake, when the exhaust brake is activated, the method described in Patent Documents 1 and 2 may not be able to properly estimate the temperature of the piston.
　本開示の目的は、ピストンの温度を適切に推定できるピストン温度推定装置およびピストン温度推定方法を提供することである。 An object of the present disclosure is to provide a piston temperature estimation device and a piston temperature estimation method that can appropriately estimate the piston temperature.
　本開示に係るピストン温度推定装置は、内燃機関を構成するピストンの温度の仮推定値を算出する仮推定部と、前記内燃機関の排気ブレーキが作動しているか否かを判定する判定部と、前記排気ブレーキの作動に伴う前記ピストンの温度の上昇量を推定する上昇量推定部と、前記判定部で前記排気ブレーキが作動していると判定された場合、前記仮推定部で算出された前記仮推定値に前記上昇量推定部で推定された前記上昇量を加算した値を前記ピストンの温度として推定し、前記判定部で前記排気ブレーキが作動していないと判定された場合、前記仮推定部で算出された前記仮推定値を前記ピストンの温度として推定する推定部と、を備える。 The piston temperature estimation device according to the present disclosure includes a tentative estimation unit that calculates a tentative estimation value of the temperature of a piston constituting the internal combustion engine, a determination unit that determines whether or not the exhaust brake of the internal combustion engine is operating, and a determination unit. The increase amount estimation unit that estimates the amount of increase in the temperature of the piston due to the operation of the exhaust brake, and the provisional estimation unit that calculates when the determination unit determines that the exhaust brake is operating. The value obtained by adding the increase amount estimated by the increase amount estimation unit to the tentative estimation value is estimated as the temperature of the piston, and when it is determined by the determination unit that the exhaust brake is not operating, the tentative estimation is performed. A unit is provided with an estimation unit that estimates the tentative estimated value calculated by the unit as the temperature of the piston.
　本開示に係るピストン温度推定方法は、内燃機関を構成するピストンの温度の仮推定値を算出するステップと、前記内燃機関の排気ブレーキが作動しているか否かを判定するステップと、前記排気ブレーキが作動していると判定された場合、前記排気ブレーキの作動に伴う前記ピストンの温度の上昇量を推定し、前記仮推定値に前記上昇量を加算した値を前記ピストンの温度として推定し、前記排気ブレーキが作動していないと判定された場合、前記仮推定値を前記ピストンの温度として推定するステップと、を実行する。 The piston temperature estimation method according to the present disclosure includes a step of calculating a tentative estimation value of the temperature of a piston constituting the internal combustion engine, a step of determining whether or not the exhaust brake of the internal combustion engine is operating, and the exhaust brake. When it is determined that is operating, the amount of increase in the temperature of the piston due to the operation of the exhaust brake is estimated, and the value obtained by adding the amount of increase to the provisional estimated value is estimated as the temperature of the piston. If it is determined that the exhaust brake is not operating, the step of estimating the tentative estimated value as the temperature of the piston is executed.
　本開示によれば、ピストンの温度を適切に推定できるピストン温度推定装置およびピストン温度推定方法を提供することができる。 According to the present disclosure, it is possible to provide a piston temperature estimation device and a piston temperature estimation method that can appropriately estimate the piston temperature.
本開示の一実施の形態に係るエンジンの概略構成を示す断面図Sectional drawing which shows the schematic structure of the engine which concerns on one Embodiment of this disclosure. 本開示の一実施の形態に係るピストン温度推定装置の構成を示すブロック図A block diagram showing a configuration of a piston temperature estimation device according to an embodiment of the present disclosure. 本開示の一実施の形態に係る排気ブレーキが作動している状態および作動していない状態におけるクランクシャフトの回転速度とピストンの温度との関係を示すグラフA graph showing the relationship between the rotational speed of the crankshaft and the temperature of the piston in the state in which the exhaust brake according to the embodiment of the present disclosure is operating and in the non-operating state. 本開示の一実施の形態に係るクランクシャフトの回転速度と排気ブレーキの作動によるピストンの温度の上昇量（推定上昇量）との関係を示すグラフA graph showing the relationship between the rotational speed of the crankshaft and the amount of increase in piston temperature (estimated amount of increase) due to the operation of the exhaust brake according to the embodiment of the present disclosure. 本開示の一実施の形態に係るピストン温度推定装置の動作の一例を示すフローチャートA flowchart showing an example of the operation of the piston temperature estimation device according to the embodiment of the present disclosure.
［実施の形態］
　以下、本開示の一実施の形態について説明する。 [Embodiment]
Hereinafter, an embodiment of the present disclosure will be described.
〔エンジンの概略構成〕
　まず、本開示のピストン温度推定装置によってピストンの温度が推定されるエンジンの概略構成について説明する。エンジンは、内燃機関の一例である。図１は、エンジンの概略構成を示す断面図である。 [Outline configuration of engine]
First, a schematic configuration of an engine in which the temperature of the piston is estimated by the piston temperature estimation device of the present disclosure will be described. The engine is an example of an internal combustion engine. FIG. 1 is a cross-sectional view showing a schematic configuration of an engine.
　図１に示すエンジン１０は、例えば、トラックのような自動車に搭載されるディーゼルエンジンである。エンジン１０は、シリンダ２０と、ピストン４０と、を備える。なお、本開示の内燃機関は、ディーゼルエンジンに限定されず、ガソリンエンジン等であっても良い。 The engine 10 shown in FIG. 1 is a diesel engine mounted on an automobile such as a truck. The engine 10 includes a cylinder 20 and a piston 40. The internal combustion engine of the present disclosure is not limited to a diesel engine, and may be a gasoline engine or the like.
　シリンダ２０の上部のシリンダヘッド２１には、インジェクタ２２が、ピストン４０の頂面中央に対向するように設けられている。シリンダヘッド２１には、インジェクタ２２の左右に位置するように、吸気ポート２３および排気ポート２４がそれぞれ設けられている。吸気ポート２３および排気ポート２４には、それぞれ吸気用バルブ２５および排気用バルブ２６が設けられている。吸気ポート２３には、吸気流路２７が接続されている。排気ポート２４には、排気流路２８が接続されている。排気流路２８には、排気ブレーキバルブ２９が設けられている。排気ブレーキバルブ２９は、バタフライ型の排気ブレーキバルブで構成されている。排気ブレーキバルブ２９は、アクチュエータ３０により駆動し、排気流路２８を閉塞することが可能に構成されている。 An injector 22 is provided on the cylinder head 21 above the cylinder 20 so as to face the center of the top surface of the piston 40. The cylinder head 21 is provided with an intake port 23 and an exhaust port 24 so as to be located on the left and right sides of the injector 22. The intake port 23 and the exhaust port 24 are provided with an intake valve 25 and an exhaust valve 26, respectively. An intake flow path 27 is connected to the intake port 23. An exhaust flow path 28 is connected to the exhaust port 24. The exhaust flow path 28 is provided with an exhaust brake valve 29. The exhaust brake valve 29 is composed of a butterfly type exhaust brake valve. The exhaust brake valve 29 is driven by the actuator 30 and is configured to be able to block the exhaust flow path 28.
　運転手が図示しない作動スイッチをオンにし、かつ、アクセルペダルから足を離した場合に、アクチュエータ３０が駆動する。そして、排気ブレーキバルブ２９によって排気流路２８が閉塞されると、排気ブレーキが作動する。なお、排気ブレーキを作動させる具体的な条件は、上記の条件に限定されるものではなく、種々の条件を用いることができる。また、運転手が作動スイッチをオフにした場合に、アクチュエータ３０が駆動し、排気ブレーキバルブ２９によって排気流路２８が開放されると、排気ブレーキの作動が解除される。 The actuator 30 is driven when the driver turns on an operation switch (not shown) and takes his / her foot off the accelerator pedal. Then, when the exhaust flow path 28 is blocked by the exhaust brake valve 29, the exhaust brake is activated. The specific conditions for operating the exhaust brake are not limited to the above conditions, and various conditions can be used. Further, when the driver turns off the operation switch, the actuator 30 is driven and the exhaust flow path 28 is opened by the exhaust brake valve 29, the operation of the exhaust brake is released.
　シリンダ２０には、図示しない冷却通路が設けられている。冷却通路に冷却水が供給されることによって、シリンダ２０が冷却される。 The cylinder 20 is provided with a cooling passage (not shown). The cylinder 20 is cooled by supplying cooling water to the cooling passage.
　ピストン４０は、シリンダ２０内を往復運動が可能なように設置されている。ピストン４０のピストン上部４１の頂面には、キャビティ４２が設けられている。ピストン４０のスカート部４３には、互いに対向する一対のピンボス部４４（図１では一方のピンボス部４４のみを図示）が設けられている。一対のピンボス部４４のピン嵌入孔には、ピストンピン４５を介してコンロッド４６の上端部が接続されている。コンロッド４６の下端部は、クランクピン４７を介して、クランクシャフト４８に接続されている。クランクシャフト４８によって、ピストン４０の往復運動が回転運動に変換される。 The piston 40 is installed so as to be able to reciprocate in the cylinder 20. A cavity 42 is provided on the top surface of the piston upper portion 41 of the piston 40. The skirt portion 43 of the piston 40 is provided with a pair of pin boss portions 44 facing each other (only one pin boss portion 44 is shown in FIG. 1). The upper end of the connecting rod 46 is connected to the pin fitting holes of the pair of pin boss portions 44 via the piston pin 45. The lower end of the connecting rod 46 is connected to the crankshaft 48 via the crankpin 47. The crankshaft 48 converts the reciprocating motion of the piston 40 into a rotary motion.
　ピストン４０には、図示しないクーリングチャンネルが設けられている。図示しないオイルジェットから噴射された冷却用オイルが、クーリングチャンネルに供給されることによって、ピストン４０が冷却される。 The piston 40 is provided with a cooling channel (not shown). Cooling oil jetted from an oil jet (not shown) is supplied to the cooling channel to cool the piston 40.
〔ピストン温度推定装置の構成〕
　次に、ピストン温度推定装置の構成について説明する。図２は、ピストン温度推定装置の構成を示すブロック図である。図３は、排気ブレーキが作動している状態および作動していない状態におけるクランクシャフトの回転速度とピストンの温度との関係を示すグラフである。図４は、クランクシャフトの回転速度と排気ブレーキの作動によるピストンの温度の上昇量との関係を示すグラフである。 [Structure of piston temperature estimation device]
Next, the configuration of the piston temperature estimation device will be described. FIG. 2 is a block diagram showing the configuration of the piston temperature estimation device. FIG. 3 is a graph showing the relationship between the rotational speed of the crankshaft and the temperature of the piston in the state in which the exhaust brake is operated and in the state in which the exhaust brake is not operated. FIG. 4 is a graph showing the relationship between the rotational speed of the crankshaft and the amount of increase in the temperature of the piston due to the operation of the exhaust brake.
　図２に示すように、ピストン温度推定装置１００は、演算部１１０と、記憶部１２０と、を備える。演算部１１０は、ハードウェアとして、例えば、ＣＰＵ（Central Processing Unit）、ＲＯＭ（Read Only Memory）、ＲＡＭ（Random Access Memory）等を有する。以下において説明する演算部１１０の各機能は、ＣＰＵがＲＯＭから読み出したコンピュータプログラムをＲＡＭ上で実行することにより実現される。 As shown in FIG. 2, the piston temperature estimation device 100 includes a calculation unit 110 and a storage unit 120. The arithmetic unit 110 has, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like as hardware. Each function of the arithmetic unit 110 described below is realized by executing a computer program read from the ROM by the CPU on the RAM.
　演算部１１０は、取得部１１１と、仮推定部１１２と、判定部１１３と、上昇量推定部１１４と、推定部１１５と、を備える。 The calculation unit 110 includes an acquisition unit 111, a provisional estimation unit 112, a determination unit 113, an increase amount estimation unit 114, and an estimation unit 115.
　取得部１１１は、各種センサからエンジンの状態を代表するエンジン状態情報を取得する。 The acquisition unit 111 acquires engine status information representing the engine status from various sensors.
　仮推定部１１２は、ピストン４０の温度を仮推定する。以下、仮推定部１１２で推定されたピストン４０の温度を、「仮推定値」という場合がある。 The tentative estimation unit 112 tentatively estimates the temperature of the piston 40. Hereinafter, the temperature of the piston 40 estimated by the tentative estimation unit 112 may be referred to as a “tentative estimation value”.
　判定部１１３は、排気ブレーキが作動しているか否かを判定する。 The determination unit 113 determines whether or not the exhaust brake is operating.
　上昇量推定部１１４は、記憶部１２０に記憶された上昇量推定式に基づいて、排気ブレーキの作動によるピストン４０の温度の上昇量を推定する。以下、上昇量推定部１１４で推定された温度の上昇量を、「推定上昇量」という場合がある。 The rise amount estimation unit 114 estimates the temperature rise amount of the piston 40 due to the operation of the exhaust brake based on the rise amount estimation formula stored in the storage unit 120. Hereinafter, the amount of temperature increase estimated by the increase amount estimation unit 114 may be referred to as "estimated amount of increase".
　推定部１１５は、仮推定値と、推定上昇量と、に基づいて、ピストン４０の温度を推定する。以下、推定部１１５で推定されたピストン４０の温度を、「推定温度」という場合がある。推定部１１５は、記憶部１２０に記憶されている複数の時定数から、所定の時定数を選択し、選択した時定数を用いて推定温度を補正する。以下、時定数を用いて補正されたピストン４０の推定温度を、「補正推定温度」という場合がある。 The estimation unit 115 estimates the temperature of the piston 40 based on the provisional estimated value and the estimated increase amount. Hereinafter, the temperature of the piston 40 estimated by the estimation unit 115 may be referred to as an “estimated temperature”. The estimation unit 115 selects a predetermined time constant from a plurality of time constants stored in the storage unit 120, and corrects the estimated temperature using the selected time constant. Hereinafter, the estimated temperature of the piston 40 corrected by using the time constant may be referred to as “corrected estimated temperature”.
　記憶部１２０は、温度仮推定マップを記憶する。温度仮推定マップは、クランクシャフト４８の単位時間当たりの回転速度（以下、「エンジン回転速度」という場合がある）と、燃料噴射量と、ピストン４０の推定温度と、の関係を示すマップである。温度仮推定マップは、仮推定部１１２における仮推定値の推定に用いられる。 The storage unit 120 stores the temperature provisional estimation map. The temperature provisional estimation map is a map showing the relationship between the rotation speed of the crankshaft 48 per unit time (hereinafter, may be referred to as "engine rotation speed"), the fuel injection amount, and the estimated temperature of the piston 40. .. The temperature tentative estimation map is used for estimating the tentative estimated value in the tentative estimation unit 112.
　記憶部１２０は、以下の式（１）で表される上昇量推定式を記憶する。上昇量推定式は、上昇量推定用情報の一例である。上昇量推定式は、上昇量推定部１１４における推定上昇量の推定に用いられる。なお、上昇量推定用情報は、温度仮推定マップのようなマップ形式であってもよい。
　　ｄＴ＝α1×Ｅ＋β1　・・・　（１）
　　　ｄＴ：推定上昇量
　　　α1，β1：係数
　　　Ｅ：エンジン回転速度 The storage unit 120 stores the increase amount estimation formula represented by the following formula (1). The increase amount estimation formula is an example of information for increase amount estimation. The increase amount estimation formula is used for estimating the estimated increase amount in the increase amount estimation unit 114. The information for estimating the amount of increase may be in a map format such as a temperature provisional estimation map.
dT = α 1 × E + β 1 ... (1)
dT: Estimated amount of increase α 1, β 1 : Coefficient E: Engine speed
　上昇量推定式は、例えば、以下のようにして求められる。 The increase amount estimation formula is obtained, for example, as follows.
　燃料が噴射されておらず、かつ、排気ブレーキが作動していない状態におけるエンジン回転速度と、ピストン４０の温度との関係を求める。横軸をエンジン回転速度、縦軸をピストン４０の温度としたグラフを作成すると、図３に三角印で示すように、エンジン回転速度が上がるにしたがって、ピストン４０の温度は上昇する。また、燃料が噴射されておらず、かつ、排気ブレーキが作動している状態におけるエンジン回転速度と、ピストン４０の温度との関係を求める。横軸をエンジン回転速度、縦軸をピストン４０の温度としたグラフを作成すると、図３に四角印で示すように、エンジン回転速度が上がるにしたがって、ピストン４０の温度は上昇する。エンジン回転速度に対するピストン４０の温度の上昇の割合は、排気ブレーキが作動していない状態と比べて大きくなっている。これは、排気ブレーキが作動すると、内燃機関のポンピング損失が大きくなりピストン４０、シリンダ２０およびシリンダヘッド２１に囲まれた燃焼室１１内の作動ガス温度が上昇すること、また排気ガスの一部が燃焼室１１内に逆流し，作動ガス温度が高く維持されることにより、ピストン４０への供給熱量が多くなり、その結果、ピストン４０の温度が上昇するためと考えられる。 The relationship between the engine rotation speed and the temperature of the piston 40 when fuel is not injected and the exhaust brake is not operating is obtained. When a graph is created in which the horizontal axis is the engine rotation speed and the vertical axis is the temperature of the piston 40, the temperature of the piston 40 increases as the engine rotation speed increases, as shown by the triangle marks in FIG. Further, the relationship between the engine rotation speed and the temperature of the piston 40 in a state where fuel is not injected and the exhaust brake is operating is obtained. When a graph is created in which the horizontal axis is the engine rotation speed and the vertical axis is the temperature of the piston 40, the temperature of the piston 40 increases as the engine rotation speed increases, as shown by a square mark in FIG. The ratio of the temperature rise of the piston 40 to the engine rotation speed is larger than that in the state where the exhaust brake is not operating. This is because when the exhaust brake is activated, the pumping loss of the internal combustion engine increases and the temperature of the working gas in the combustion chamber 11 surrounded by the piston 40, the cylinder 20 and the cylinder head 21 rises, and a part of the exhaust gas is discharged. It is considered that the backflow into the combustion chamber 11 and the high working gas temperature are maintained, so that the amount of heat supplied to the piston 40 increases, and as a result, the temperature of the piston 40 rises.
　次に、各エンジン回転速度における、排気ブレーキが作動している状態のピストンの温度から、排気ブレーキが作動していない状態のピストン４０の温度を減じることによって、各エンジン回転速度における排気ブレーキの作動によるピストン４０の温度の上昇量を求める。その結果を図４に丸印で示す。そして、丸印で示すデータの一次近似式（実線で示す）を上昇量推定式（式（１））として求める。なお、上昇量推定式の作成に用いるピストン４０の温度は、シミュレーションで求めた値であっても良いし、実測値であっても良い。 Next, by subtracting the temperature of the piston 40 in the state where the exhaust brake is not operating from the temperature of the piston in the state where the exhaust brake is operating at each engine rotation speed, the operation of the exhaust brake at each engine rotation speed is performed. The amount of increase in the temperature of the piston 40 is obtained. The results are shown by circles in FIG. Then, the linear approximation formula (shown by the solid line) of the data indicated by the circles is obtained as the rise amount estimation formula (formula (1)). The temperature of the piston 40 used for creating the rise amount estimation formula may be a value obtained by simulation or an actually measured value.
　記憶部１２０は、第１の時定数、第２の時定数、第３の時定数、第４の時定数、第５の時定数、第６の時定数、第７の時定数および第８の時定数を記憶する。第１～第８の時定数は、ピストン４０の温度の変化速度の度合いを示す。第１～第８の時定数は、推定部１１５における補正推定温度の算出に用いられる。 The storage unit 120 has a first time constant, a second time constant, a third time constant, a fourth time constant, a fifth time constant, a sixth time constant, a seventh time constant, and an eighth time constant. Memorize the time constant. The first to eighth time constants indicate the degree of change rate of the temperature of the piston 40. The first to eighth time constants are used to calculate the corrected estimated temperature in the estimation unit 115.
　第１～第４の時定数は、ピストン４０に冷却用オイルが噴射されていない状態のときに選択される。 The first to fourth time constants are selected when the cooling oil is not injected into the piston 40.
　第１の時定数は、ピストン４０の温度が低下し、燃料噴射が行われておらず、かつ、エンジン１０が停止している場合に選択される。第２の時定数は、ピストン４０の温度が低下し、燃料噴射が行われておらず、かつ、エンジン１０が運転している場合に選択される。 The first time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 has stopped. The second time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 is running.
　ピストン４０の温度が低下し、燃料噴射が行われておらず、かつ、エンジン１０が運転している場合には、冷却オイルおよび冷却水がエンジン１０内を循環するので、ピストン４０の温度の低下速度は速くなる。 When the temperature of the piston 40 drops, fuel injection is not performed, and the engine 10 is operating, the cooling oil and the cooling water circulate in the engine 10, so that the temperature of the piston 40 drops. The speed will be faster.
　一方、ピストン４０の温度が低下し、燃料噴射が行われておらず、かつ、エンジン１０が停止している場合には、冷却オイルおよび冷却水の循環が停止する。このため、ピストン４０の温度の低下速度は遅くなる。したがって、第１の時定数の値は、第２の時定数の値よりも大きい。 On the other hand, when the temperature of the piston 40 drops, fuel injection is not performed, and the engine 10 is stopped, the circulation of the cooling oil and the cooling water is stopped. Therefore, the rate of decrease in the temperature of the piston 40 becomes slow. Therefore, the value of the first time constant is larger than the value of the second time constant.
　第３の時定数は、ピストン４０の温度が低下し、燃料噴射が行われている場合に選択される。燃料噴射が行われている場合には、エンジン１０は燃料を燃焼させているので、燃料噴射量の変化に対してピストン４０の温度の変化が大きく、ピストン４０の温度の低下速度は燃料噴射が行われていない場合と同等あるいは速くなる。したがって、第３の時定数の値は、第１の時定数の値よりも小さく、第２の時定数と同等あるいは小さい。 The third time constant is selected when the temperature of the piston 40 has dropped and fuel injection is being performed. When fuel injection is performed, since the engine 10 burns fuel, the change in the temperature of the piston 40 is large with respect to the change in the fuel injection amount, and the rate of decrease in the temperature of the piston 40 is the fuel injection. Equivalent or faster than if not done. Therefore, the value of the third time constant is smaller than the value of the first time constant, and is equal to or smaller than the value of the second time constant.
　第４の時定数は、ピストン４０の温度が上昇している場合に選択される。第４の時定数の値は、第３の時定数の値よりも大きい。 The fourth time constant is selected when the temperature of the piston 40 is rising. The value of the fourth time constant is larger than the value of the third time constant.
　第５～第８の時定数は、ピストン４０に冷却用オイルが噴射されている状態に選択される。 The fifth to eighth time constants are selected in a state where the cooling oil is injected into the piston 40.
　第５の時定数は、ピストン４０の温度が低下し、燃料噴射が行われておらず、かつ、エンジン１０が停止している場合に選択される。ピストン４０に冷却用オイルが噴射されている場合には、ピストン４０に冷却用オイルが噴射されてない場合に比べて、ピストン４０の温度の低下速度は速くなる。したがって、第５の時定数の値は、第１の時定数の値よりも小さい。 The fifth time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 has stopped. When the cooling oil is injected into the piston 40, the temperature of the piston 40 drops faster than when the cooling oil is not injected into the piston 40. Therefore, the value of the fifth time constant is smaller than the value of the first time constant.
　第６の時定数は、ピストン４０の温度が低下し、燃料噴射が行われておらず、かつ、エンジン１０が運転している場合に選択される。ピストン４０に冷却用オイルが噴射されている場合には、ピストン４０に冷却用オイルが噴射されてない場合に比べて、ピストン４０の温度の低下速度は速くなる。したがって、第６の時定数の値は、第２の時定数の値よりも小さい。 The sixth time constant is selected when the temperature of the piston 40 has dropped, fuel injection has not been performed, and the engine 10 is running. When the cooling oil is injected into the piston 40, the temperature of the piston 40 drops faster than when the cooling oil is not injected into the piston 40. Therefore, the value of the sixth time constant is smaller than the value of the second time constant.
　第７の時定数は、ピストン４０の温度が低下し、燃料噴射が行われている場合に選択される。ピストン４０に冷却用オイルが噴射されている場合には、ピストン４０に冷却用オイルが噴射されてない場合に比べて、ピストン４０の温度の低下速度は速くなる。したがって、第７の時定数の値は、第３の時定数の値よりも小さい。 The seventh time constant is selected when the temperature of the piston 40 has dropped and fuel injection is being performed. When the cooling oil is injected into the piston 40, the temperature of the piston 40 drops faster than when the cooling oil is not injected into the piston 40. Therefore, the value of the seventh time constant is smaller than the value of the third time constant.
　第８の時定数は、ピストン４０の温度が上昇している場合に選択される。ピストン４０に冷却用オイルが噴射されている場合には、ピストン４０に冷却用オイルが噴射されてない場合に比べて、ピストン４０の温度の上昇速度は速くなる。したがって、第８の時定数の値は、第４の時定数の値よりも小さい。 The eighth time constant is selected when the temperature of the piston 40 is rising. When the cooling oil is injected into the piston 40, the temperature rise rate of the piston 40 is faster than that in the case where the cooling oil is not injected into the piston 40. Therefore, the value of the eighth time constant is smaller than the value of the fourth time constant.
　以下、取得部１１１、仮推定部１１２、判定部１１３、上昇量推定部１１４、および推定部１１５の詳細な構成について説明する。 Hereinafter, the detailed configurations of the acquisition unit 111, the provisional estimation unit 112, the determination unit 113, the increase amount estimation unit 114, and the estimation unit 115 will be described.
（取得部１１１）
　取得部１１１は、エンジン状態情報として、エンジン回転速度、エンジン１０の燃焼室１１への燃料噴射量、燃料噴射時期、燃料噴射圧力、ピストン４０への冷却用オイルの噴射の有無、冷却用オイルの油圧、冷却用オイルの油温、吸気温度、吸気圧力、吸入空気量、吸入空気温度、シリンダ２０の冷却水温度、作動スイッチの操作に基づく排気ブレーキの作動信号、排気温度、ＥＧＲ（Exhaust Gas Recirculation）ガス流量等を取得する。 (Acquisition unit 111)
The acquisition unit 111, as engine state information, includes engine rotation speed, fuel injection amount to the combustion chamber 11 of the engine 10, fuel injection timing, fuel injection pressure, presence / absence of injection of cooling oil to the piston 40, and cooling oil. Hydraulic pressure, oil temperature of cooling oil, intake air temperature, intake pressure, intake air amount, intake air temperature, cooling water temperature of cylinder 20, operation signal of exhaust brake based on operation of operation switch, exhaust temperature, EGR (Exhaust Gas Recirculation) ) Obtain the gas flow rate, etc.
（仮推定部１１２）
　仮推定部１１２は、取得部１１１で取得されたエンジン回転速度および燃料噴射量と、記憶部１２０に記憶された温度仮推定マップと、に基づいて、ピストン４０の温度を推定する。仮推定部１１２は、温度仮推定マップ等に基づき推定した温度を、取得部１１１で取得された燃料噴射時期等の情報を用いて補正して、当該補正した値を仮推定値として推定する。 (Tentative estimation unit 112)
The tentative estimation unit 112 estimates the temperature of the piston 40 based on the engine rotation speed and the fuel injection amount acquired by the acquisition unit 111 and the temperature tentative estimation map stored in the storage unit 120. The tentative estimation unit 112 corrects the temperature estimated based on the temperature tentative estimation map or the like using the information such as the fuel injection timing acquired by the acquisition unit 111, and estimates the corrected value as the tentative estimation value.
（判定部１１３）
　判定部１１３は、取得部１１１で取得されたエンジン状態情報に基づいて、排気ブレーキが作動しているか否かを判定する。 (Determining unit 113)
The determination unit 113 determines whether or not the exhaust brake is operating based on the engine state information acquired by the acquisition unit 111.
（上昇量推定部１１４）
　上昇量推定部１１４は、判定部１１３で排気ブレーキが作動していると判定された場合、記憶部１２０に記憶された上昇量推定式（式（１））に、取得部１１１で取得されたエンジン回転速度を代入することによって、推定上昇量を求める。 (Rise amount estimation unit 114)
When the determination unit 113 determines that the exhaust brake is operating, the increase amount estimation unit 114 is acquired by the acquisition unit 111 in the increase amount estimation formula (formula (1)) stored in the storage unit 120. By substituting the engine speed, the estimated amount of increase is obtained.
（推定部１１５）
　推定部１１５は、判定部１１３で排気ブレーキが作動していると判定された場合、仮推定部１１２で算出された仮推定値に、上昇量推定部１１４で算出された推定上昇量を加算した値を、ピストン４０の推定温度として算出する。推定部１１５は、判定部１１３で排気ブレーキが作動していないと判定された場合、仮推定部１１２で算出された仮推定値を、ピストン４０の推定温度として推定する。 (Estimating unit 115)
When the determination unit 113 determines that the exhaust brake is operating, the estimation unit 115 adds the estimated increase amount calculated by the increase amount estimation unit 114 to the provisional estimation value calculated by the provisional estimation unit 112. The value is calculated as the estimated temperature of the piston 40. When the determination unit 113 determines that the exhaust brake is not operating, the estimation unit 115 estimates the tentative estimation value calculated by the tentative estimation unit 112 as the estimated temperature of the piston 40.
　ピストン４０の推定温度と、実際の温度とは、エンジン１０の状態によって異なる場合がある。特に、エンジン１０の状態が過渡的に変化する状況では、推定温度と実際の温度との違いが顕著である。そして、エンジン１０の状態によって、推定温度の変化の速さの度合いを示す時定数が変化する。 The estimated temperature of the piston 40 and the actual temperature may differ depending on the state of the engine 10. In particular, in a situation where the state of the engine 10 changes transiently, the difference between the estimated temperature and the actual temperature is remarkable. Then, depending on the state of the engine 10, the time constant indicating the degree of change in the estimated temperature changes.
　そこで、推定部１１５は、エンジン１０の状態に対応する時定数を用いて、推定温度をさらに補正して、補正推定温度を算出する。 Therefore, the estimation unit 115 further corrects the estimated temperature by using the time constant corresponding to the state of the engine 10, and calculates the corrected estimated temperature.
　推定部１１５は、記憶部１２０に記憶されている複数の時定数の中から、推定温度の変化状況、エンジン１０の運転状態、および、ピストン４０への冷却用オイルの噴射状態に基づいて、所定の時定数を選択する。推定部１１５は、選択した所定の時定数に基づいて、推定温度を補正する。 The estimation unit 115 determines from among a plurality of time constants stored in the storage unit 120, based on the change state of the estimated temperature, the operating state of the engine 10, and the injection state of the cooling oil to the piston 40. Select the time constant of. The estimation unit 115 corrects the estimated temperature based on the selected predetermined time constant.
　推定部１１５は、新たに推定した推定温度と、１周期前に推定した推定温度との差分値を所定の時定数で除算した値を、１周期前の推定温度に加算することにより、推定温度を補正する。これにより、推定温度を、実際のピストン４０の温度の変化の速さに対応するものに補正することができる。 The estimation unit 115 divides the difference value between the newly estimated estimated temperature and the estimated temperature estimated one cycle before by a predetermined time constant, and adds the value obtained by dividing the difference value to the estimated temperature one cycle before, so that the estimated temperature is estimated. To correct. Thereby, the estimated temperature can be corrected to correspond to the speed of change in the temperature of the actual piston 40.
　推定温度の変化の速度が速い場合には、推定部１１５は、相対的に小さい時定数を選択する。これにより、補正推定温度は、新たに推定された推定温度の影響が大きくなる。 When the rate of change in the estimated temperature is fast, the estimation unit 115 selects a relatively small time constant. As a result, the corrected estimated temperature is greatly affected by the newly estimated estimated temperature.
　また、推定温度の変化の速度が遅い場合には、推定部１１５は、相対的に大きい時定数を選択する。これにより、補正推定温度は、過去に推定された推定温度の影響が大きくなる。 If the rate of change in the estimated temperature is slow, the estimation unit 115 selects a relatively large time constant. As a result, the corrected estimated temperature is greatly affected by the estimated temperature estimated in the past.
　推定部１１５は、例えば以下の式（２）を用いて補正推定温度ＴPSCを算出する。なお、補正推定温度の算出式は式（２）に限定されない。
　　ＴPSC＝ＴPSO＋γ×（ＴPS－ＴPSO）／τ　・・・　（２）
　　　ＴPSO：１周期前に推定された推定温度
　　　ＴPS：新たに推定された推定温度
　　　γ：所定値
　　　τ：時定数 The estimation unit 115 calculates the corrected estimated temperature T PSC using, for example, the following equation (2). The formula for calculating the corrected estimated temperature is not limited to the formula (2).
T PSC = T PSO + γ × ( TPS-T PSO ) / τ ・ ・ ・ (2)
T PSO : Estimated temperature estimated one cycle before T PS : Estimated temperature newly estimated γ: Predetermined value τ: Time constant
〔ピストン温度推定装置の動作〕
　次に、ピストン温度推定装置１００の動作について説明する。図５は、ピストン温度推定装置の動作の一例を示すフローチャートである。 [Operation of piston temperature estimation device]
Next, the operation of the piston temperature estimation device 100 will be described. FIG. 5 is a flowchart showing an example of the operation of the piston temperature estimation device.
　まず、図５に示すように、ピストン温度推定装置１００の取得部１１１は、エンジン状態情報を取得する（ステップＳ１）。 First, as shown in FIG. 5, the acquisition unit 111 of the piston temperature estimation device 100 acquires engine state information (step S1).
　次に、ピストン温度推定装置１００の仮推定部１１２は、取得部１１１で取得されたエンジン状態情報に含まれるエンジン回転速度および燃料噴射量と、記憶部１２０に記憶された温度仮推定マップと、に基づいて、仮推定値を算出する（ステップＳ２）。 Next, the tentative estimation unit 112 of the piston temperature estimation device 100 includes the engine rotation speed and the fuel injection amount included in the engine state information acquired by the acquisition unit 111, the temperature tentative estimation map stored in the storage unit 120, and the tentative estimation map. A tentative estimate is calculated based on (step S2).
　次に、ピストン温度推定装置１００の判定部１１３は、取得部１１１で取得されたエンジン状態情報に含まれる作動スイッチの操作に関する情報に基づいて、排気ブレーキが作動しているか否かを判定する（ステップＳ３）。 Next, the determination unit 113 of the piston temperature estimation device 100 determines whether or not the exhaust brake is operating based on the information regarding the operation of the operation switch included in the engine state information acquired by the acquisition unit 111. Step S3).
　判定部１１３で排気ブレーキが作動していると判定された場合（ステップＳ３：ＹＥＳ）、ピストン温度推定装置１００の上昇量推定部１１４は、記憶部１２０に記憶された上昇量推定式（式（１））と、取得部１１１で取得されたエンジン回転速度と、に基づいて、推定上昇量を推定する（ステップＳ４）。 When it is determined by the determination unit 113 that the exhaust brake is operating (step S3: YES), the increase amount estimation unit 114 of the piston temperature estimation device 100 uses the increase amount estimation formula (formula (formula)) stored in the storage unit 120. The estimated amount of increase is estimated based on 1)) and the engine rotation speed acquired by the acquisition unit 111 (step S4).
　次に、ピストン温度推定装置１００の推定部１１５は、仮推定値に推定上昇量を加算した値を、ピストン４０の推定温度として算出する（ステップＳ５）。 Next, the estimation unit 115 of the piston temperature estimation device 100 calculates a value obtained by adding the estimated increase amount to the provisional estimated value as the estimated temperature of the piston 40 (step S5).
　一方、判定部１１３で排気ブレーキが作動していないと判定された場合（ステップＳ３：ＮＯ）、推定部１１５は、仮推定値をピストン４０の推定温度として推定する（ステップＳ６）。 On the other hand, when the determination unit 113 determines that the exhaust brake is not operating (step S3: NO), the estimation unit 115 estimates the tentative estimated value as the estimated temperature of the piston 40 (step S6).
　ステップＳ５またはステップＳ６の処理の後、推定部１１５は、取得部１１１で取得されたエンジン状態情報に含まれるエンジン１０の運転状態および冷却用オイルの噴射状態と、推定温度の変化状況と、に基づいて、時定数を選択する（ステップＳ７）。 After the processing of step S5 or step S6, the estimation unit 115 determines the operating state of the engine 10 and the injection state of the cooling oil included in the engine state information acquired by the acquisition unit 111, and the change state of the estimated temperature. Based on this, a time constant is selected (step S7).
　次に、推定部１１５は、算出式（式（２））と、ステップＳ７で選択した時定数と、推定温度と、に基づいて、補正推定温度を算出する（ステップＳ８）。ステップＳ８で算出された補正推定温度は、記憶部１２０に記憶され、例えばエンジン１０の寿命予測に用いられる。なお、１周期目のピストン温度推定処理を行う場合、式（２）の１周期前に推定された推定温度ＴPSOが存在しない。この場合、オイル温度あるいは別途計算して求めたキャビティ４２の口元部等の温度や、予め設定された値を推定温度ＴPSOとして用いても良い。 Next, the estimation unit 115 calculates the correction estimated temperature based on the calculation formula (formula (2)), the time constant selected in step S7, and the estimated temperature (step S8). The corrected estimated temperature calculated in step S8 is stored in the storage unit 120 and is used, for example, for predicting the life of the engine 10. When the piston temperature estimation process in the first cycle is performed, the estimated temperature T PSO estimated one cycle before the equation (2) does not exist. In this case, the oil temperature, the temperature of the mouth of the cavity 42 calculated separately, or a preset value may be used as the estimated temperature T PSO .
　次に、取得部１１１は、ピストン温度推定処理を終了させるか否かを判定する（ステップＳ９）。 Next, the acquisition unit 111 determines whether or not to end the piston temperature estimation process (step S9).
　取得部１１１は、例えば、エンジン１０の運転が終了した場合等、ピストン温度推定処理を終了させると判定した場合（ステップＳ９：ＹＥＳ）、処理を終了させる。一方、取得部１１１は、ピストン温度推定処理を終了させないと判定した場合（ステップＳ９：ＮＯ）、ステップＳ１の処理を行う。 When the acquisition unit 111 determines that the piston temperature estimation process is to be terminated, for example, when the operation of the engine 10 is completed (step S9: YES), the acquisition unit 111 terminates the process. On the other hand, when the acquisition unit 111 determines that the piston temperature estimation process is not terminated (step S9: NO), the acquisition unit 111 performs the process of step S1.
〔実施の形態の作用効果〕
　ピストン温度推定装置１００は、エンジン回転速度および燃料噴射量と、温度仮推定マップと、に基づいて、ピストン４０の温度の仮推定値を推定する。ピストン温度推定装置１００は、排気ブレーキが作動している場合、排気ブレーキの作動に伴うピストン４０の温度の推定上昇量を算出し、当該推定上昇量に仮推定値を加算した値を、ピストン４０の推定温度として算出する。一方、ピストン温度推定装置１００は、排気ブレーキが作動していない場合、仮推定値をピストン４０の推定温度として推定する。このため、ピストン温度推定装置１００は、排気ブレーキの作動に伴い上昇するピストン４０の温度を反映させて、推定温度を算出することができる。したがって、ピストン温度推定装置１００は、ピストン４０の温度を適切に推定できる。そして、適切に推定されたピストン４０の温度に基づいて、例えばエンジン１０の寿命予測を精度良く行うことができる。 [Action and effect of the embodiment]
The piston temperature estimation device 100 estimates a tentative estimation value of the temperature of the piston 40 based on the engine rotation speed, the fuel injection amount, and the tentative temperature estimation map. When the exhaust brake is operating, the piston temperature estimation device 100 calculates an estimated increase in temperature of the piston 40 due to the operation of the exhaust brake, and adds a tentative estimated value to the estimated increase in the piston 40. Calculated as the estimated temperature of. On the other hand, the piston temperature estimation device 100 estimates the tentative estimated value as the estimated temperature of the piston 40 when the exhaust brake is not operating. Therefore, the piston temperature estimation device 100 can calculate the estimated temperature by reflecting the temperature of the piston 40 that rises with the operation of the exhaust brake. Therefore, the piston temperature estimation device 100 can appropriately estimate the temperature of the piston 40. Then, for example, the life of the engine 10 can be accurately predicted based on the appropriately estimated temperature of the piston 40.
　ピストン温度推定装置１００は、上昇量推定式に取得部１１１で取得されたエンジン回転速度を代入することによって、推定上昇量を算出する。このため、上昇量推定式にエンジン回転速度を代入するだけの簡単な方法で、推定上昇量を算出することができる。 The piston temperature estimation device 100 calculates the estimated increase amount by substituting the engine rotation speed acquired by the acquisition unit 111 into the increase amount estimation formula. Therefore, the estimated increase amount can be calculated by a simple method of substituting the engine rotation speed into the increase amount estimation formula.
　ピストン温度推定装置１００は、推定温度を推定温度の変化速度の度合いを示す時定数に基づいて補正した、補正推定温度を算出する。このため、推定時点でのピストン４０の温度を、より適切に推定することができる。 The piston temperature estimation device 100 calculates a corrected estimated temperature obtained by correcting the estimated temperature based on a time constant indicating the degree of change rate of the estimated temperature. Therefore, the temperature of the piston 40 at the time of estimation can be estimated more appropriately.
　演算部１１０は、ピストン４０の温度の変化状況、エンジン回転速度、燃料噴射量および冷却用オイルの噴射状態に基づいて、複数の時定数の中から選択された所定の時定数を用いて、補正推定温度を算出する。このため、実際のピストン４０の温度を精度良く推定することができる。 The calculation unit 110 corrects using a predetermined time constant selected from a plurality of time constants based on the change state of the temperature of the piston 40, the engine rotation speed, the fuel injection amount, and the injection state of the cooling oil. Calculate the estimated temperature. Therefore, the actual temperature of the piston 40 can be estimated accurately.
［実施の形態の変形例］
　本開示は、これまでに説明した実施の形態に示されたものに限られないことは言うまでも無く、その趣旨を逸脱しない範囲内で、種々の変形を加えることができる。 [Modified example of the embodiment]
Needless to say, the present disclosure is not limited to those shown in the embodiments described above, and various modifications can be made without departing from the spirit of the present disclosure.
　上昇量推定式として、上記式（１）の代わりに、以下の式（３）で示すような図４の丸印で示すデータの二次多項式（一点鎖線で示す）を用いてもよい。また、上昇量推定式として、上記式（１）の代わりに、三次多項式や四次多項式を用いてもよい。
　　ｄＴ＝α2×Ｅ2＋β2×Ｅ＋η2　・・・　（３）
　　　ｄＴ：推定上昇量
　　　α2，β2，η2：係数
　　　Ｅ：エンジン回転速度 As the increase amount estimation formula, instead of the above formula (1), a quadratic polynomial (indicated by a alternate long and short dash line) of the data shown by the circles in FIG. 4 as shown in the following formula (3) may be used. Further, as the ascending amount estimation formula, a cubic polynomial or a quaternary polynomial may be used instead of the above formula (1).
dT = α 2 × E 2 + β 2 × E + η 2・ ・ ・ (3)
dT: Estimated amount of increase α 2, β 2, η 2 : Coefficient E: Engine speed
　第１～第８の時定数を使い分ける構成としたが、これに限定されない。例えば、ピストン４０の温度の変化状況、エンジン運転状態および冷却用オイルの噴射状態に基づいて、時定数をさらに細分化しても良い。時定数の細分化にあたり、その他のパラメータを考慮しても良い。 The first to eighth time constants were used properly, but it is not limited to this. For example, the time constant may be further subdivided based on the change state of the temperature of the piston 40, the engine operating state, and the injection state of the cooling oil. Other parameters may be taken into consideration when subdividing the time constant.
　推定部１１５に推定温度を補正する機能を設けなくても良い。 It is not necessary to provide the estimation unit 115 with a function for correcting the estimated temperature.
　２０２０年９月２４日出願の特願２０２０－１６００７５の日本出願に含まれる明細書、図面および要約書の開示内容は、すべて本願に援用される。 All disclosures of the specification, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2020-160075 filed on September 24, 2020 are incorporated herein by reference.
　本開示の構成は、ピストン温度推定装置およびピストン温度推定方法に適用することができる。 The configuration of the present disclosure can be applied to the piston temperature estimation device and the piston temperature estimation method.
　１０　エンジン
　１１　燃焼室
　２０　シリンダ
　２１　シリンダヘッド
　２２　インジェクタ
　２３　吸気ポート
　２４　排気ポート
　２５　吸気用バルブ
　２６　排気用バルブ
　２７　吸気流路
　２８　排気流路
　２９　排気ブレーキバルブ
　３０　アクチュエータ
　４０　ピストン
　４１　ピストン上部
　４２　キャビティ
　４３　スカート部
　４４　ピンボス部
　４５　ピストンピン
　４６　コンロッド
　４７　クランクピン
　４８　クランクシャフト
　１００　ピストン温度推定装置
　１１０　演算部
　１１１　取得部
　１１２　仮推定部
　１１３　判定部
　１１４　上昇量推定部
　１１５　推定部
　１２０　記憶部 10 Engine 11 Combustion chamber 20 Cylinder 21 Cylinder head 22 Injector 23 Intake port 24 Exhaust port 25 Intake valve 26 Exhaust valve 27 Intake flow path 28 Exhaust flow path 29 Exhaust brake valve 30 Actuator 40 Piston 41 Piston upper part 42 Cavity 43 Skirt part 44 Pin boss 45 Piston pin 46 Conrod 47 Cylinder pin 48 Crank shaft 100 Piston temperature estimation device 110 Calculation unit 111 Acquisition unit 112 Temporary estimation unit 113 Judgment unit 114 Rise amount estimation unit 115 Estimating unit 120 Storage unit

Claims (5)

  1. 　内燃機関を構成するピストンの温度の仮推定値を算出する仮推定部と、
    　前記内燃機関の排気ブレーキが作動しているか否かを判定する判定部と、
    　前記排気ブレーキの作動に伴う前記ピストンの温度の上昇量を推定する上昇量推定部と、
    　前記判定部で前記排気ブレーキが作動していると判定された場合、前記仮推定部で算出された前記仮推定値に前記上昇量推定部で推定された前記上昇量を加算した値を前記ピストンの温度として推定し、前記判定部で前記排気ブレーキが作動していないと判定された場合、前記仮推定部で算出された前記仮推定値を前記ピストンの温度として推定する推定部と、を備える、ピストン温度推定装置。     A tentative estimation unit that calculates a tentative estimate of the temperature of the pistons that make up the internal combustion engine,
    A determination unit for determining whether or not the exhaust brake of the internal combustion engine is operating,
    An increase amount estimation unit that estimates an increase amount of the temperature of the piston due to the operation of the exhaust brake,
    When it is determined by the determination unit that the exhaust brake is operating, the value obtained by adding the increase amount estimated by the increase amount estimation unit to the provisional estimation value calculated by the provisional estimation unit is added to the piston. When the determination unit determines that the exhaust brake is not operating, the estimation unit includes an estimation unit that estimates the provisional estimation value calculated by the provisional estimation unit as the temperature of the piston. , Piston temperature estimator.
  2. 　前記上昇量推定部は、前記内燃機関のクランクシャフトの回転速度に基づいて、前記ピストンの温度の上昇量を推定する、請求項１に記載のピストン温度推定装置。 The piston temperature estimation device according to claim 1, wherein the increase amount estimation unit estimates an increase amount of the temperature of the piston based on the rotation speed of the crankshaft of the internal combustion engine.
  3. 　前記上昇量推定部は、前記内燃機関の燃焼室へ燃料が噴射されていない状態における前記排気ブレーキの作動に伴う前記ピストンの温度の上昇量を推定する、請求項１に記載のピストン温度推定装置。 The piston temperature estimation device according to claim 1, wherein the increase amount estimation unit estimates an increase amount of the temperature of the piston due to the operation of the exhaust brake in a state where fuel is not injected into the combustion chamber of the internal combustion engine. ..
  4. 　前記推定部は、前記推定したピストンの温度を、前記ピストンの温度の変化速度の度合いを示す時定数に基づいて補正する、請求項１に記載のピストン温度推定装置。 The piston temperature estimation device according to claim 1, wherein the estimation unit corrects the estimated piston temperature based on a time constant indicating the degree of change in the temperature of the piston.
  5. 　内燃機関を構成するピストンの温度の仮推定値を算出するステップと、
    　前記内燃機関の排気ブレーキが作動しているか否かを判定するステップと、
    　前記排気ブレーキが作動していると判定された場合、前記排気ブレーキの作動に伴う前記ピストンの温度の上昇量を推定し、前記仮推定値に前記上昇量を加算した値を前記ピストンの温度として推定し、前記排気ブレーキが作動していないと判定された場合、前記仮推定値を前記ピストンの温度として推定するステップと、を実行する、ピストン温度推定方法。     Steps to calculate a tentative estimate of the temperature of the pistons that make up the internal combustion engine,
    The step of determining whether or not the exhaust brake of the internal combustion engine is operating, and
    When it is determined that the exhaust brake is operating, the amount of increase in the temperature of the piston due to the operation of the exhaust brake is estimated, and the value obtained by adding the amount of increase to the provisional estimated value is defined as the temperature of the piston. A piston temperature estimation method for estimating and executing a step of estimating the provisional estimated value as the temperature of the piston when it is determined that the exhaust brake is not operating.
PCT/JP2021/033844 2020-09-24 2021-09-15 Piston temperature estimation device and piston temperature estimation method WO2022065145A1 (en)

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