JP2016050508A - Temperature estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature estimation device which accurately estimates at least either of a temperature of a cylinder wall of an engine and a temperature of a refrigerant in a water jacket of a cylinder block.SOLUTION: A temperature estimation device comprises a temperature estimation part in which a temperature of a cylinder wall 21 of an engine E, a temperature of a refrigerant in a water jacket 23 of a cylinder block 22 of the engine E, and a temperature of the refrigerant after circulation in the water jacket 23 are set as reference points related to temperature estimation, and which estimates at least either of a temperature T2 of the cylinder wall 21 and a temperature T3 of the refrigerant in the water jacket 23 on the basis of the reference points in a state that the refrigerant is not circulated to the water jacket 23 on the basis of thermal balance at the cylinder wall 21, thermal balance at the refrigerant in the water jacket 23, and thermal balance at the refrigerant after circulation in the water jacket 23.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a temperature estimation device that estimates at least one of a temperature of a cylinder wall of an engine and a temperature of a refrigerant in a water jacket of an engine cylinder block.

  Conventionally, during the driving of the engine, since the refrigerant is always circulated through the water jacket of the cylinder block of the engine, there is a correlation between the temperature of the refrigerant flowing through the water jacket and the temperature state of the engine. For this reason, the temperature state of the engine can be grasped by detecting the temperature of the refrigerant after flowing through the water jacket, and ignition control and injection control can be performed according to the temperature. In recent years, however, fuel consumption has been improved by promoting warm-up during cold weather, and control has been performed to shut off the refrigerant circulating in the water jacket and limit the flow rate during cold weather. Such control causes a temperature distribution in each part of the engine, and the coolant may boil locally in the water jacket. For this reason, it has become difficult to perform optimal ignition control and injection control based on the temperature of the refrigerant after circulation through a water jacket that has been conventionally performed, and countermeasures have been studied (for example, Patent Documents 1-3).

  The control device for a variable water pump disclosed in Patent Document 1 includes a stop control unit that performs control to stop driving of a variable water pump that pumps cooling water when the engine is warmed up. The control unit for the variable water pump drives or stops the variable water pump according to the estimated coolant temperature at the start of the engine and the estimated coolant temperature at a predetermined portion of the engine when the engine is warmed up.

  The control apparatus for an internal combustion engine disclosed in Patent Document 2 includes a refrigerant temperature detection unit that detects a refrigerant temperature as a refrigerant temperature detection value, an outdoor temperature detection unit that detects a temperature outside the combustion chamber of the internal combustion engine as an outdoor temperature detection value, and an internal combustion engine. Specific part temperature estimation means for estimating the temperature of the specific part of the engine based on the detected refrigerant temperature value. The specific part temperature estimating means calculates the amount of heat given from the outside of the combustion chamber of the specific part by the amount of heat given from the outside of the combustion chamber by the refrigerant and the ratio of the amount of heat received by the specific part and the refrigerant, The temperature of the specific part is corrected based on the outdoor temperature detection value and the amount of heat given to the specific part.

  An internal combustion engine control apparatus disclosed in Patent Document 3 includes an operating state detecting unit that detects an operating state of the internal combustion engine, and a gas temperature estimation that estimates a gas temperature in the combustion chamber from the operating state of the internal combustion engine detected by the operating state detecting unit. Means and estimation means for simultaneously estimating the combustion chamber wall temperature and the coolant temperature inside the internal combustion engine. The estimating means calculates a change amount of the combustion chamber wall temperature from the difference between the amount of heat received by the combustion chamber wall from the combustion gas and the amount of heat given to the cooling water from the combustion chamber wall and the heat capacity of the combustion chamber wall; The combustion chamber wall temperature and the cooling water temperature inside the internal combustion engine are estimated based on the amount of heat received by the cooling water from the combustion chamber wall and the second equation for calculating the amount of change in the cooling water temperature from the heat capacity of the cooling water.

International Publication No. 2011/021511 Pamphlet JP2011-231679A JP 2006-300031 A

  The technique described in Patent Document 1 controls the operation of the variable water pump based on the coolant temperature. When the circulation of the cooling water is stopped, the estimation error increases because the cooling water temperature changes according to the elapsed time after the stop. Further, it is not assumed that the cooling water temperature is estimated when the flow rate of the cooling water is set to a very small amount or the cooling water temperature is estimated when the engine is restarted. The techniques described in Patent Documents 2 and 3 estimate the temperature of the cylinder wall and the temperature of the refrigerant circulating in the water jacket of the cylinder block using the difference in the amount of heat between each part, the temperature of the refrigerant, the outside air temperature, and the like. However, since the temperature of the refrigerant is considered only after circulation through the water jacket of the cylinder block, it is possible to accurately estimate the temperature of the refrigerant present in the water jacket of the cylinder block when the refrigerant circulation is stopped. Can not.

  In view of the above problems, an object of the present invention is to provide a temperature estimation device capable of accurately estimating at least one of the temperature of the cylinder wall of the engine and the temperature of the refrigerant in the water jacket of the cylinder block of the engine. It is in.

  In order to achieve the above object, the temperature estimation apparatus according to the present invention has the following features: the temperature of the cylinder wall of the engine, the temperature of the refrigerant in the water jacket of the cylinder block of the engine, and the refrigerant after circulation through the water jacket Is set as a reference point for temperature estimation, and based on the reference point, a first heat balance calculation unit that calculates a heat balance in the cylinder wall of the engine as a first heat balance based on the reference point A second heat balance calculator that calculates a heat balance in the refrigerant in the water jacket of the cylinder block of the engine as a second heat balance, and heat in the refrigerant after flowing through the water jacket based on the reference point. A third heat balance calculating unit for calculating a balance as a third heat balance, the first heat balance, the second heat balance, and the third heat balance. And a temperature estimation unit that estimates at least one of the temperature of the cylinder wall and the temperature of the refrigerant in the water jacket in a state where the refrigerant does not flow through the water jacket. It is in.

  With such a characteristic configuration, it is possible to estimate the temperature of each part of the engine by increasing the reference point for temperature estimation compared to the case where the temperature of each part of the engine has been estimated conventionally. It is possible to accurately estimate the temperature of the cylinder wall, the temperature of the refrigerant in the water jacket of the cylinder block of the engine, and the like. Therefore, even when the engine is warming up in the cold state, the temperature state of the engine can be accurately grasped, so that optimal ignition control and injection control can be performed.

  In addition, the temperature estimation unit is used as a parameter that varies depending on the concentration of the refrigerant in the calculation of the first heat balance, the second heat balance, and the third heat balance, and the temperature estimation unit causes the refrigerant to flow through the water jacket. In the state where only the parameter is changed, the temperature of the refrigerant in the water jacket is estimated in advance for each predetermined concentration, and the temperature of the refrigerant for each predetermined concentration estimated in advance is It is preferable to provide an update unit that updates the current parameter with the parameter used to estimate the temperature of the refrigerant closest to the temperature of the refrigerant detected by the temperature sensor after the refrigerant flows through the water jacket.

  With such a configuration, even if the characteristics of the refrigerant change according to use, the concentration of the refrigerant used for each calculation of the first heat balance, the second heat balance, and the third heat balance Since the parameter is updated based on the current state of the refrigerant, it is possible to reduce an error caused by a change in the characteristic of the refrigerant included in the estimation result estimated by the temperature estimation unit. Therefore, even when the characteristics of the refrigerant change, it is possible to accurately estimate the temperature of each part.

  Further, the difference between the ambient temperature of the engine before the temperature estimation unit estimates at least one of the temperature of the cylinder wall and the temperature of the refrigerant in the water jacket, and the estimation result estimated by the temperature estimation unit It is preferable that a correction unit that corrects the estimation result to a low temperature side with a large correction amount is provided as the value is larger.

  For example, when the engine is repeatedly started and stopped until the heat distribution in each part of the engine becomes uniform, the estimation result by the temperature estimation unit becomes a value higher than the actual temperature, and before the first start of the engine The inventors of the present application have found that the larger the difference between the ambient temperature of the engine and the estimation result estimated by the temperature estimation unit, the greater the difference between the estimation result by the temperature estimation unit and the actual temperature. . Therefore, according to this configuration, the correction unit uses the correction amount set according to the difference between the ambient temperature of the engine before the temperature estimation unit performs temperature estimation and the estimation result of the temperature estimation unit. Since the estimation result is corrected, the estimation result can be brought close to the actual temperature. Therefore, the temperature of each part can be accurately estimated even if the engine is frequently operated and stopped, for example, a hybrid vehicle or a vehicle having an idling stop function.

It is a block diagram which shows the structure of a temperature estimation apparatus. It is a model figure which shows the heat balance concerning the estimation by a temperature estimation apparatus. It is a figure which shows the estimation result at the time of changing the parameter regarding the density | concentration of a refrigerant | coolant, and a detection result. It is a figure which shows the estimation result in the case of repeating an operation | movement and a stop of an engine, and actual temperature.

  The temperature estimation device according to the present invention is configured to have a function capable of accurately estimating at least one of the temperature of the cylinder wall of the engine and the temperature of the refrigerant in the water jacket of the cylinder block of the engine. Hereinafter, the temperature estimation apparatus 1 of the present embodiment will be described. FIG. 1 is a block diagram schematically showing the configuration of the temperature estimation device 1, and FIG. 2 is a model diagram showing a heat balance related to estimation by the temperature estimation device 1.

  As shown in FIG. 1, the temperature estimation device 1 includes a first heat balance calculation unit 11, a second heat balance calculation unit 12, a third heat balance calculation unit 13, a temperature estimation unit 14, an update unit 15, and a correction unit 16. Each functional part is configured. Each of these functional units is a hardware that uses the CPU as a core member to perform various processes related to the estimation of the temperature of the cylinder wall 21 of the engine E and the temperature of the refrigerant in the water jacket 23 of the cylinder block 22 of the engine E. Or built in software or both.

  In order to accurately estimate the temperature of the cylinder wall 21 of the engine E and the temperature of the refrigerant in the water jacket 23 of the cylinder block 22 of the engine E, the temperature estimation device 1 has three reference points (hereinafter referred to as “hot points”). ) Is set for temperature estimation. In the present embodiment, as shown in FIG. 2, the three hot spots are the temperature T 1 of the refrigerant detected by the temperature sensor 31, the temperature T 2 of the cylinder wall 21, and the water jacket 23 after flowing through the water jacket 23. It corresponds to the temperature T3 of the refrigerant inside. In the present embodiment, based on these three hot spots, the heat balance is calculated by the first heat balance calculation unit 11, the second heat balance calculation unit 12, and the third heat balance calculation unit 13 shown below. .

  The first heat balance calculation unit 11 calculates the heat balance in the cylinder wall 21 of the engine E as the first heat balance. The cylinder wall 21 of the engine E corresponds to a wall portion of a combustion chamber in which, for example, gasoline that is the fuel of the engine E is burned. The heat balance is the sum of the amount of heat released and the amount of heat received. Therefore, the first heat balance calculation unit 11 calculates the sum of the heat release amount and the heat reception amount related to the cylinder wall 21 of the engine E as the first heat balance. The first heat balance corresponds to the product of the differential value of the temperature T2 of the cylinder wall 21 and the heat capacity of the cylinder wall 21.

  Specifically, the first heat balance, which is the heat balance of the cylinder wall 21, is the amount of heat Q 0 generated by the combustion of the engine E, the amount of heat transfer Q 1 from the cylinder wall 21 to the refrigerant in the water jacket 23, and the cylinder wall 21. The sum of the heat transfer amount Q2 to the refrigerant outside the water jacket 23 and the heat amount Q6 radiated from the cylinder wall 21 to the outside air, if the heat reception amount is positive and the heat release amount is negative, the first heat balance is Q0-Q1. It can be calculated by -Q2-Q6. In addition, the white arrow in FIG. 2 shows only the direction of the amount of heat and the amount of heat transfer, and does not show the size.

  The second heat balance calculation unit 12 calculates the heat balance of the refrigerant in the water jacket 23 of the cylinder block 22 of the engine E as the second heat balance. The cylinder block 22 of the engine E corresponds to a housing that constitutes a cylinder 25 that houses the piston 24. The water jacket 23 of the cylinder block 22 is a refrigerant flow path that is provided in the cylinder block 22 and cools the cylinder 25. Therefore, the second heat balance calculation unit 12 calculates the sum of the heat release amount and the heat reception amount related to the refrigerant in the flow passage in the water jacket 23 as the second heat balance. The second heat balance includes the differential value of the temperature T3 of the refrigerant in the water jacket 23, the density of the refrigerant in the water jacket 23, the volume of the refrigerant in the water jacket 23, and the heat capacity of the refrigerant in the water jacket 23. This is the product of

  Specifically, the second heat balance, which is the heat balance of the refrigerant in the water jacket 23 of the cylinder block 22, includes the heat capacity W1 of the refrigerant after flowing through the water jacket 23, the heat capacity W2 of the refrigerant in the water jacket 23, the cylinder wall. The heat transfer amount Q1 from 21 to the refrigerant in the water jacket 23, the heat transfer amount Q3 when the refrigerant flows from the water jacket 23 to the outside of the water jacket 23, and the refrigerant flowing through the water jacket 23 receive heat from the outside air. Assuming that the total amount of heat Q5 is positive, the amount of heat received is positive and the amount of heat released is negative, the second heat balance can be calculated as W1-W2 + Q1-Q3 + Q5.

  The third heat balance calculation unit 13 calculates the heat balance of the refrigerant after flowing through the water jacket 23 as the third heat balance. The refrigerant after distribution through the water jacket 23 is a refrigerant discharged from the water jacket 23. Therefore, the third heat balance calculation unit 13 calculates the sum of the heat release amount and the heat reception amount related to the refrigerant discharged from the water jacket 23 as the third heat balance. The third heat balance includes the differential value of the refrigerant temperature T1 detected by the temperature sensor 31, the density of the refrigerant after distribution through the water jacket 23, the volume of the refrigerant after distribution through the water jacket 23, and the water jacket 23. Is the product of the heat capacity of the refrigerant after distribution.

  Specifically, the third heat balance, which is the heat balance of the refrigerant after flowing through the cylinder block 22, is obtained from the heat capacity W 1 of the refrigerant after flowing through the water jacket 23, the heat capacity W 2 of the refrigerant in the water jacket 23, and the cylinder wall 21. Heat transfer amount Q2 to the refrigerant outside the water jacket 23, heat transfer amount Q3 when the refrigerant flows from inside the water jacket 23 to the outside of the water jacket 23, and heat amount radiated from the refrigerant after flowing through the water jacket 23 to the outside air Assuming that Q4 is the sum, the amount of heat received is positive, and the amount of heat released is negative, the third heat balance can be calculated as W2-W1 + Q2 + Q3-Q4.

  Here, the heat quantity Q0 can be obtained from the engine speed and the output torque. Further, the amount Q1 of heat transfer depends on a difference between the temperature T2 and the temperature T3, a predetermined coefficient (thermal conductivity from the cylinder wall 21 to the refrigerant in the water jacket 23, and a ground contact area of the water jacket 23 with respect to the cylinder wall 21). Product). Further, the heat transfer amount Q2 depends on a difference between the temperature T2 and the temperature T1, a predetermined coefficient (the thermal conductivity from the cylinder wall 21 to the refrigerant in the water jacket 23, and the refrigerant outside the water jacket 23 with respect to the cylinder wall 21). Multiply by the product of the contact area of the flow passage). Further, the amount Q3 of heat transfer depends on a difference between the temperature T3 and the temperature T1, a predetermined coefficient (the thermal conductivity of the refrigerant flowing from the water jacket 23 to the outside of the water jacket 23, the flow path in the water jacket 23 and the water The product of the contact area with the flow passage outside the jacket 23 is multiplied by a value obtained by dividing the product of the flow passage through which the refrigerant in the water jacket 23 communicates with the temperature sensor 31). Further, the amount of heat Q6 is obtained by adding a predetermined coefficient (the product of the thermal conductivity from the cylinder wall 21 to the refrigerant in the water jacket 23 and the ground contact area of the outside air to the cylinder wall 21) to the difference between the temperature T2 and the outside air temperature. It can be obtained by multiplying. The heat capacity W1 can be obtained from the product of the specific heat of the refrigerant after flowing through the water jacket 23, the temperature T1, and the flow rate of the refrigerant flowing through the water jacket 23. Further, the heat capacity W2 of the refrigerant in the water jacket 23 can be obtained from the product of the specific heat of the refrigerant in the cylinder block 22, the temperature T3, and the flow rate of the refrigerant flowing in the cylinder block 22.

  Based on the first heat balance, the second heat balance, and the third heat balance, the temperature estimation unit 14 determines the temperature T2 of the cylinder wall 21 and the inside of the water jacket 23 in a state where the refrigerant is not flowing through the water jacket 23. The refrigerant temperature T3 is estimated. The first heat balance is transmitted from the first heat balance calculator 11. The second heat balance is transmitted from the second heat balance calculator 12. The third heat balance is transmitted from the third heat balance calculator 13. The state where the refrigerant is not circulating in the water jacket 23 is a state where the refrigerant is not circulating through the water jacket 23 for the purpose of warming up the engine E when the engine E is cold (when the ambient temperature of the engine E is low). Say. Under such a state, the temperature estimation unit 14 solves differential equations relating to the first heat balance, the second heat balance, and the third heat balance, thereby the temperature T2 of the cylinder wall 21 and the refrigerant in the water jacket 23. The temperature T3 is calculated. This calculation result corresponds to an estimation result by the temperature estimation unit 14.

  Specifically, when the temperature T3 of the refrigerant in the water jacket 23 is estimated, differential equations relating to the first heat balance, the second heat balance, and the third heat balance are Laplace transformed, and the Laplace transformed second temperature is obtained. The difference between the second heat balance and the third heat balance is solved, and the temperature change amount of the refrigerant in the water jacket 23 in a predetermined time is calculated. This can be obtained by adding the temperature T1 of the refrigerant detected by the temperature sensor 31 to this result. Further, when estimating the temperature T2 of the cylinder wall 21, Laplace transform is performed on differential equations relating to the first heat balance, the second heat balance, and the third heat balance, and the first heat balance and the third heat balance are calculated. Solving for the difference, the temperature change amount of the cylinder wall 21 for a predetermined time is calculated. This can be obtained by adding the temperature T1 of the refrigerant detected by the temperature sensor 31 to this result.

  The temperature T3 of the refrigerant in the water jacket 23 is calculated by calculating a second heat balance, which is a heat balance in the refrigerant in the water jacket 23, and obtaining a temperature change amount by the second heat balance. It can also be obtained by adding the temperature T1 of the refrigerant detected by the temperature sensor 31. Further, the temperature T2 of the cylinder wall 21 is calculated by calculating a first heat balance, which is a heat balance in the cylinder wall 21, and obtaining a temperature change amount due to the first heat balance, and this temperature change amount is detected by the temperature sensor 31. It can also be obtained by adding the temperature T1 of the refrigerant. Note that the amount of temperature change due to the first heat balance can be obtained by Q = mcΔT. Where Q is the first heat balance, m is the mass of the cylinder block 22, c is the specific heat of the cylinder block 22, and ΔT is the amount of temperature change. Further, the temperature rise due to the second heat balance can also be obtained by Q = mcΔT, where Q is the second heat balance, m is the mass of the refrigerant in the water jacket 23, c is the specific heat of the refrigerant, ΔT Is the amount of temperature change.

  Here, specific heat, viscosity, and thermal conductivity that change according to the refrigerant concentration are used as parameters for calculating the first heat balance, the second heat balance, and the third heat balance. For example, in a state where the refrigerant is circulating in the water jacket 23, the refrigerant temperature T <b> 1 near the temperature sensor 31 estimated by the temperature estimation unit 14 and the refrigerant temperature T <b> 1 detected by the temperature sensor 31 are substantially equal. Should be a value. However, when the refrigerant concentration changes due to, for example, replacement or deterioration of the refrigerant, the specific heat, viscosity, and thermal conductivity parameters depending on the concentration change from the initial values, and the temperature estimation unit 14 Therefore, a difference occurs between the temperature T1 by the temperature sensor 31 and the temperature T1 of the refrigerant by the temperature sensor 31, and an error is included in the temperature T3 of the refrigerant by the temperature estimation unit 14.

  Therefore, the temperature estimation unit 14 changes only the parameters in a state where the refrigerant is circulating in the water jacket 23, and estimates the temperature of the refrigerant in the water jacket 23 for each predetermined concentration in advance. That is, the current refrigerant is circulated in the water jacket 23, and only the parameters relating to the refrigerant concentration are changed, and the estimation result is acquired. This estimation result is obtained by changing the parameter for each predetermined concentration (for example, every 10%). The estimation results for each refrigerant concentration thus obtained are shown in (1)-(5) of FIG.

  Next, the update unit 15 has the highest temperature T1 of the refrigerant detected by the temperature sensor 31 after the refrigerant is actually circulated through the water jacket 23 among the refrigerant temperatures estimated in advance. Update the parameters related to the current refrigerant concentration with the parameters used to estimate the temperature of the nearby refrigerant. That is, the temperature sensor 31 detects the temperature of the refrigerant used when the temperature estimation unit 14 described above changes the parameter for each predetermined concentration to estimate the temperature of the refrigerant in the water jacket 23, and this detection result is the highest. Update the current parameter with the parameter for the near estimation result. According to the example of FIG. 3, the temperature T1 detected by the temperature sensor 31 is the closest to (4) among the estimation results (1) to (5) indicated by the broken line. The current parameter is updated with the used parameter. Thereby, even if the characteristic of the refrigerant changes, it is possible to accurately estimate the temperature of each part by updating the parameters.

  Here, as described above, the temperature estimation unit 14 estimates the temperature T2 of the cylinder wall 21 and the temperature T3 of the refrigerant in the water jacket 23, but the engine E repeatedly operates and stops as shown in FIG. In this case, the temperature distribution of each part of the engine E is not uniform, and the error included in the estimated value tends to increase. This error increases as the difference between the ambient temperature of the engine at the start of the engine E and the estimation result by the temperature estimation unit 14 increases, and the estimation result by the temperature estimation unit 14 increases.

  Therefore, the correction unit 16 includes the ambient temperature of the engine E before the temperature estimation unit 14 estimates the temperature T2 of the cylinder wall 21 and the temperature of the refrigerant in the water jacket 23, and the estimation result estimated by the temperature estimation unit 14. The larger the difference is, the larger the correction amount is corrected to the low temperature side. The ambient temperature of the engine E can be detected by, for example, a temperature sensor 31 before circulating the refrigerant or a temperature sensor provided around the engine E. As shown in FIG. 4, when the ambient temperature of the engine E before starting the engine E is T0, the result estimated by the temperature estimation unit 14 (indicated by a broken line in FIG. 4) is higher as the temperature T0 is higher. The actual temperature (shown by a solid line in FIG. 4) is higher. Therefore, the correction unit 16 corrects the estimation result to be smaller by using a larger correction amount as the difference between the ambient temperature of the engine E before starting the engine E and the result estimated by the temperature estimation unit 14 is larger. To do. Thereby, even when the temperature distribution of each part of the engine E is not uniform, the temperature of each part of the engine E can be accurately estimated.

[Other Embodiments]
In the above embodiment, the temperature estimation unit 14 has been described as estimating the temperature of the cylinder wall 21 and the temperature of the refrigerant in the water jacket 23, but the temperature estimation unit 14 is configured to estimate the temperature of the cylinder wall 21 and the refrigerant in the water jacket 23. It is also possible to adopt a configuration for estimating one of the temperatures.

  In the above embodiment, the update unit 15 has been described as updating the parameter relating to the concentration of the refrigerant used for the temperature estimation by the temperature estimation unit. However, the update unit 15 may be configured not to update the parameter. In this case, the temperature estimation unit 14 may not change the parameters and estimate the temperature T3 of the refrigerant in the water jacket 23 while the refrigerant is circulating in the water jacket 23.

  In the above embodiment, the correction unit 16 is estimated by the temperature estimation unit 14 and the ambient temperature of the engine E before the temperature estimation unit 14 estimates the temperature T2 of the cylinder wall 21 and the temperature of the refrigerant in the water jacket 23. It has been described that the estimation result is corrected to the low temperature side with a larger correction amount as the difference from the estimation result is larger. However, the correction unit 16 may be configured not to correct the estimation result of the temperature estimation unit 14. Regardless of the difference between the temperature T2 of the cylinder wall 21 and the ambient temperature of the engine E before the temperature estimation of the refrigerant in the water jacket 23 and the estimation result estimated by the temperature estimation unit 14. It is also possible to adopt a configuration in which the estimation result is corrected to the low temperature side with a constant correction amount.

  The present invention can be used in a temperature estimation device that estimates at least one of the temperature of the cylinder wall of the engine and the temperature of the refrigerant in the water jacket of the cylinder block of the engine.

1: Temperature estimation device 11: First heat balance calculation unit 12: Second heat balance calculation unit 13: Third heat balance calculation unit 14: Temperature estimation unit 15: Update unit 16: Correction unit 21: Cylinder wall 22: Cylinder block 23: Water jacket 31: Temperature sensor E: Engine T1: Temperature (the temperature of the refrigerant after distribution through the water jacket)
T2: Temperature (temperature of the refrigerant in the water jacket)
T3: Temperature (cylinder wall temperature)

Claims (3)

The temperature of the cylinder wall of the engine, the temperature of the refrigerant in the water jacket of the cylinder block of the engine, and the temperature of the refrigerant after flowing through the water jacket are set as reference points for temperature estimation,
A first heat balance calculation unit that calculates a heat balance in the cylinder wall of the engine as a first heat balance based on the reference point;
A second heat balance calculation unit that calculates a heat balance of the refrigerant in the water jacket of the cylinder block of the engine as a second heat balance based on the reference point;
Based on the reference point, a third heat balance calculation unit that calculates a heat balance in the refrigerant after flowing through the water jacket as a third heat balance;
Based on the first heat balance, the second heat balance, and the third heat balance, the temperature of the cylinder wall and the refrigerant in the water jacket in a state where the refrigerant does not flow through the water jacket. A temperature estimation unit for estimating at least one of the temperatures;
A temperature estimation device comprising: The first heat balance, the second heat balance, and the third heat balance are used as parameters that change according to the concentration of the refrigerant in the calculation of the third heat balance,
The temperature estimating unit changes only the parameter in a state where the refrigerant is circulating in the water jacket, and estimates the temperature of the refrigerant in the water jacket for each predetermined concentration in advance.
Used to estimate the temperature of the refrigerant closest to the temperature of the refrigerant detected by the temperature sensor after circulating the refrigerant through the water jacket, of the temperature of the refrigerant for each predetermined concentration estimated in advance. The temperature estimation apparatus according to claim 1, further comprising an update unit that updates the current parameter with a parameter.   There is a large difference between the ambient temperature of the engine before the temperature estimation unit estimates at least one of the temperature of the cylinder wall and the temperature of the refrigerant in the water jacket, and the estimation result estimated by the temperature estimation unit. The temperature estimation apparatus according to claim 1, further comprising a correction unit that corrects the estimation result to a low temperature side with a larger correction amount.

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