JP2023154883A - Control device and control method - Google Patents

Abstract

To provide a control device and a control method capable of appropriately controlling a flow rate of a cooling medium.SOLUTION: A control device, which controls a flow rate of a cooling medium circulated in a cooling flow passage of an internal combustion engine, comprises: acquisition means which acquires a detection value of a temperature of the cooling medium at an outlet of the cooling flow passage; calculation means which calculates an inverse of the flow rate so as to compensate a delay in time until a difference between the temperature of the cooling medium at an inlet of the cooling flow passage and the detection value reaches a target value in accordance with flow rate control on the basis of a correlation between a difference in temperatures of the cooling medium between the inlet and the outlet of the cooling flow passage and the inverse of the flow rate and also calculates the flow rate on the basis of the inverse thereof; and correction means which calculates a target flow rate from the target value on the basis of the correlation, predicts at least either delay in response time with respect to the flow control or wasteful time from the target flow rate and corrects the difference on the basis of a prediction result.SELECTED DRAWING: Figure 9

Description

The present invention relates to a control device and a control method.

For example, a control device for an internal combustion engine such as an engine controls the flow rate of a cooling medium (for example, cooling water) discharged from a pump to the internal combustion engine (see, for example, Patent Document 1). For example, the control device quickly reduces the flow rate of the cooling medium to increase the temperature of the internal combustion engine in order to reduce cooling loss and mechanical loss of the internal combustion engine and improve combustion efficiency, and also to increase the temperature of the internal combustion engine due to knocking of the internal combustion engine. In order to suppress the increase in loss and abnormalities caused by boiling of the coolant, it is necessary to quickly increase the flow rate of the coolant to lower the temperature of the internal combustion engine.

Unexamined Japanese Patent Publication No. 2016-3587

For example, the control device compensates for the response delay to the control based on the temperature of the coolant detected by the water temperature sensor at the outlet of the cooling flow path of the internal combustion engine (hereinafter referred to as the outlet temperature), and also adjusts the temperature so that the temperature reaches the target value. Control the flow rate of cooling medium. However, since an error occurs in the control value in response to a change in the flow rate of the cooling medium, there is a risk that the temperature of the cooling medium may overshoot, for example, and not converge quickly.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device and a control method that can appropriately control the flow rate of a cooling medium.

The control device of the present invention is a control device for controlling the flow rate of a cooling medium circulating through a cooling passage of an internal combustion engine, and includes an acquisition unit for acquiring a detected value of the temperature of the cooling medium at an outlet of the cooling passage. , to compensate for a delay until the temperature difference of the cooling medium at the inlet and outlet of the cooling channel reaches a target value, based on the difference between the temperature of the cooling medium at the inlet of the cooling channel and the detected value. a calculation means for calculating a control value of the flow rate; a command means for commanding a pump that circulates the cooling medium in the cooling flow path to output according to the control value; and a delay in response to the output command. The apparatus includes a correction means for predicting at least one of the time and the dead time from the target flow rate corresponding to the target value, and correcting the difference based on the prediction result.

In the above control device, the correction means records the history of the temperature difference of the cooling medium in chronological order as a response to the output command, and obtains a value before the dead time from the history of the temperature difference. It may also be used to correct the difference.

In the above control device, the correction means may record the history of the temperature difference in time series based on the correlation between the temperature difference and the reciprocal of the flow rate from the current flow rate of the cooling medium.

In the above control device, the acquisition means may acquire the rotation speed of the pump, and the correction means may estimate the current flow rate of the cooling medium from the rotation speed.

In the above control device, the correction means may calculate a time constant according to the target flow rate, and predict the delay time from the time constant.

In the above control device, the calculation means may calculate a time constant according to the target flow rate, and compensate for the delay based on the time constant.

In the above control device, the calculation means may calculate the control value using a temperature of the cooling medium at an inlet of the cooling channel as a fixed value.

The control method of the present invention is a control method for controlling the flow rate of a cooling medium circulating through a cooling passage of an internal combustion engine, in which a detected value of the temperature of the cooling medium at an outlet of the cooling passage is acquired, and the cooling Based on the difference between the temperature of the cooling medium at the inlet of the cooling channel and the detected value, the flow rate is adjusted to compensate for the delay until the temperature difference of the cooling medium at the inlet and outlet of the cooling channel reaches the target value. calculate a control value, instruct a pump that circulates the cooling medium in the cooling flow path to output according to the control value, and at least one of a delay time and a dead time in response to the output command, This is a method in which a computer performs a process of predicting from a target flow rate corresponding to the target value and correcting the difference based on the prediction result.

In the above control method, in the process of correcting the difference based on the prediction result, the history of the temperature difference of the cooling medium is recorded in time series as a response to the output command, and the history of the temperature difference of the cooling medium is recorded based on the history of the temperature difference. A method may also be adopted in which a value before the dead time is acquired and used to correct the difference.

In the above control method, in the process of correcting the difference based on the prediction result, the history of the temperature difference is calculated from the current flow rate of the cooling medium based on the correlation between the temperature difference and the reciprocal of the flow rate. A method of recording in series may also be used.

The above control method may be a method of acquiring the rotation speed of the pump and estimating the current flow rate of the cooling medium from the rotation speed in the process of correcting the difference based on the prediction result.

The above control method may be a method of calculating a time constant according to the target flow rate and predicting the delay time from the time constant in the process of correcting the difference based on the prediction result.

The above control method may be a method of calculating a time constant according to the target flow rate in the process of calculating the control value of the flow rate, and compensating for a delay based on the time constant.

The above control method may be a method of calculating the control value by setting the temperature of the cooling medium at the inlet of the cooling channel as a fixed value in the process of calculating the control value of the flow rate.

According to the present invention, the flow rate of the cooling medium can be appropriately controlled.

FIG. 1 is a configuration diagram showing an example of an engine control system. FIG. 1 is a configuration diagram showing an example of an ECU (Electronic Control Unit). It is a figure which shows an example of a heat amount map data table. FIG. 3 is a diagram showing an example of the correlation between the flow rate of cooling water and the difference in inlet and outlet water temperatures in a thermal equilibrium state. FIG. 3 is a diagram showing an example of the correlation between the reciprocal of the flow rate of cooling water and the difference in inlet and outlet water temperatures. FIG. 3 is a diagram showing an example of a time constant data table. It is a figure which shows an example of a dead time data table. It is a figure which shows an example of a convergence water temperature difference data table. It is a block diagram showing an example of a feedback control system of a plant. It is a flowchart which shows an example of flow control operation of ECU. It is a flowchart which shows an example of the calculation process of the assumed entrance and exit water temperature difference. It is a figure which shows the time change of the outlet water temperature in a comparative example. It is a figure which shows the time change of the outlet water temperature in an Example.

(Control system configuration)
FIG. 1 is a configuration diagram showing an example of a control system 9 for the engine 2. As shown in FIG. The control system 9 is mounted on a vehicle (including a hybrid vehicle) that uses the engine 2 as a drive source. The control system 9 includes an ECU 1, an engine 2, a cooling system 3, and a sensor system 4.

Engine 2 is an example of an internal combustion engine, and includes a cylinder head 2a and a cylinder block 2b. Water jackets 20 and 23 through which cooling water for cooling the engine 2 flows are provided inside the cylinder head 2a and the cylinder block 2b, respectively. Cooling water is an example of a cooling medium, and water jackets 20 and 23 are examples of cooling channels.

The cylinder block 2b is provided with an inlet 24 of the water jacket 23, and the cylinder head 2a is provided with outlets 21 and 22 of the water jacket 20. Cooling water circulates between the cooling system 3 and the water jackets 20 and 23. Cooling water flows from the cooling system 3 through the inlet 24 into the water jacket 23, and from the water jacket 23 flows into the water jacket 20 of the cylinder head 2a. Cooling water flows from the water jacket 20 into the cooling system 3 through the outlets 21 and 22.

The cooling system 3 includes an electric water pump (EWP) 30, a thermostat (T/S) 31, a radiator 32, a heater 33, a transmission thermal fluid exchanger (ATF/W) 34, and an EGR (Exhaust Gas Recirculation) cooler (EGR/C). ) 35, and an outlet water temperature sensor 36. The cooling system 3 also includes an EGR channel 37, a distribution channel 38, return channels 390, 391, an ATF channel 380, a heater channel 381, and a radiator channel 382 as circulation channels through which cooling water circulates. has.

EWP30 is an example of a pump. EWP 30 sends cooling water to water jackets 20 and 23. Cooling water flows from the EWP 30 into the water jacket 23 through the inlet 24. In this manner, the EWP 30 circulates cooling water to the water jackets 20 and 23.

Cooling water flows into the EGR cooler 35 from the outlet 22 of the water jacket 20. The EGR cooler 35 cools the exhaust gas of the engine 2 with cooling water. The EGR cooler 35 is provided in the EGR passage 37, and cooling water is discharged from the EGR cooler 35 to the EGR passage 37.

Cooling water flows into the outlet water temperature sensor 36 from the outlet 22 of the water jacket 20 . The outlet water temperature sensor 36 detects the temperature of the cooling water at the outlet 22 (hereinafter referred to as "outlet water temperature"). An outlet water temperature sensor 36 is provided in the distribution channel 38.

The distribution channel 38 branches into an ATF channel 380, a heater channel 381, and a radiator channel 382. The ATF/W 34, the heater 33, and the radiator 32 are provided in the ATF flow path 380, the heater flow path 381, and the radiator flow path 382, respectively. The cooling water flows from the outlet water temperature sensor 36 through the distribution channel 38 and is divided into an ATF channel 380, a heater channel 381, and a radiator channel 382.

The ATF/W 34 performs heat exchange between the transmission cooling oil and the like and the cooling water in the ATF flow path 380. The heater 33 exchanges heat between the air in the cabin of the vehicle in which the control system 9 is installed and the cooling water in the heater flow path 381 . The radiator 32 exchanges heat between the outside air of the vehicle and the cooling water in the radiator flow path 382.

The EGR passage 37, the ATF passage 380, and the heater passage 381 merge into one return passage 390. Further, the cooling water cooled by the radiator 32 is discharged to the other return flow path 391. That is, the EGR passage 37, the ATF passage 380, and the heater passage 381 function as detour passages that bypass the radiator 32. The cooling water that has flowed through the EGR passage 37, the ATF passage 380, and the heater passage 381 is returned to the EWP 30 from the return passage 390. The cooling water that has flowed through the radiator flow path 382 flows back to the EWP 30 from the return flow path 391 when the on-off valve 311 of the thermostat 31 is open as described below.

A thermostat 31 is provided in the return channels 390 and 391. The thermostat 31 is provided with a temperature detection section 310 and an on-off valve 311. The temperature detection unit 310 detects the temperature of the cooling water flowing from the EGR flow path 37, the ATF flow path 380, and the heater flow path 381. The on-off valve 311 blocks or allows the flow of cooling water flowing from the radiator 32 to pass through.

The temperature detection unit 310 includes, for example, wax that expands depending on the temperature of the cooling water. When the cooling water reaches a predetermined temperature (hereinafter referred to as "valve opening determination water temperature"), the on-off valve 311 is opened by an on-off mechanism (not shown) in accordance with the expansion of the wax.

Therefore, if the temperature of the cooling water flowing in from the EGR flow path 37, ATF flow path 380, and heater flow path 381 is less than the valve opening determination water temperature, the on-off valve 311 is closed, so the cooling water cooled by the radiator 32 is Water is not returned to the EWP 30, and only the cooling water in the EGR passage 37, ATF passage 380, and heater passage 381 is returned to the EWP 30. In addition, if the temperature of the cooling water that has flowed in from the EGR passage 37, ATF passage 380, and heater passage 381 is equal to or higher than the valve opening determination water temperature, the on-off valve 311 is open, so the cooling water cooled by the radiator 32 is The water is returned to the EWP 30 together with the cooling water in the EGR channel 37, ATF channel 380, and heater channel 381. In this case, the on-off valve 311 opens so that the cooling water passes through the radiator 32.

ECU1 is an example of a control device. The ECU 1 controls the torque of the engine 2. The ECU 1 sets a target value for the outlet water temperature of the cooling water according to the state of the engine 2. The ECU 1 acquires the detected value of the outlet water temperature sensor 36, and controls the discharge amount of the EWP 30 based on the detected value so that the outlet water temperature approaches the target value. That is, the ECU 1 controls the flow rate of cooling water circulating through the distribution channel 38 and the EGR channel 37.

The sensor system 4 outputs various detected values to the ECU 1. The sensor system 4 includes, for example, an air flow meter (AFM) 40, a throttle opening sensor (TA) 41, an intake pressure sensor (INP) 42, an exhaust pressure sensor (EXP) 43, and a rotation speed sensor (RS) 44. . AFM 40 detects the flow rate (intake amount) of air taken into engine 2. TA41 detects the opening degree of a throttle (not shown) provided in the engine 2. The intake pressure sensor 42 and the exhaust pressure sensor 43 detect the intake pressure and exhaust pressure of the engine 2, respectively. The rotation speed sensor 44 detects the rotation speed of the EWP 30. The ECU 1 controls the torque of the engine 2 and the flow rate of cooling water based on each detection value of the sensor system 4.

(ECU configuration)
FIG. 2 is a configuration diagram showing an example of the ECU 1. As shown in FIG. The ECU 1 includes a CPU (Central Processing Unit) 10, a ROM (Read Only Memory) 11, a RAM (Random Access Memory) 12, a storage memory 13, and an input/output port 14. The CPU 10 is electrically connected to a ROM 11, a RAM 12, a storage memory 13, and an input/output port 14 via a bus 19 so that signals can be input and output to each other. Note that the ECU 1 is an example of a computer.

The ROM 11 stores a program for driving the CPU 10. The RAM 12 functions as a working memory for the CPU 10. The input/output port 14 inputs and outputs various signals to and from, for example, the sensor system 4, the outlet water temperature sensor 36, and the EWP 30. Thereby, the CPU 10 communicates with the sensor system 4, the outlet water temperature sensor 36, and the EWP 30.

When the CPU 10 reads a program from the ROM 11, it forms an operation control section 100, a detected value acquisition section 101, a torque control section 102, a flow rate calculation section 103, a water temperature difference correction section 104, and a rotation speed command section 105 as functions. Further, the storage memory 13 stores a heat amount map data table 130, a time constant data table 131, a dead time data table 132, and a convergence water temperature difference data table 133. The storage memory 13 is realized by a flash memory, for example.

The operation control unit 100 controls the entire operation of the ECU 1. The operation control section 100 instructs the detected value acquisition section 101, the torque control section 102, the flow rate calculation section 103, the water temperature difference correction section 104, and the rotation speed command section 105 to operate according to a predetermined sequence. At this time, the operation control section 100 relays variables related to various processes between the detected value acquisition section 101, the torque control section 102, the flow rate calculation section 103, and the water temperature difference correction section 104.

The detected value acquisition unit 101 is an example of an acquisition means. The detected value acquisition unit 101 acquires various detected values from the sensor system 4 according to instructions from the operation control unit 100. For example, the detected value acquisition unit 101 acquires the detected value of the outlet water temperature from the outlet water temperature sensor 36. The detected value acquisition unit 101 acquires detected values at different cycles for each detected value, for example.

Torque control section 102 controls the torque of engine 2 according to instructions from operation control section 100 . At this time, the torque control unit 102 uses various detected values of the sensor system 4 for control.

The flow rate calculation unit 103 is an example of calculation means. The flow rate calculation unit 103 calculates the flow rate of cooling water based on the detected value of the outlet water temperature sensor 36. The flow rate calculation unit 103 calculates the temperature of the cooling water at the inlet based on the difference between the temperature of the cooling water at the inlet 24 (hereinafter referred to as "inlet water temperature") and the detected value of the outlet water temperature (hereinafter referred to as "detected water temperature difference value"). The control value of the flow rate is calculated so as to compensate for the delay until the temperature difference between the cooling water at the outlet 24 and the outlet 21 (hereinafter referred to as "inlet/outlet water temperature difference") reaches the target value. Here, the flow rate calculation unit 103 sets a target value for the outlet water temperature of the cooling water according to the state of the engine 2 determined from various detected values of the sensor system 4, and calculates the difference between the target value and the inlet water temperature. Calculate the target value of water temperature difference.

As described later, the flow rate calculation unit 103 calculates the reciprocal of the flow rate from the detected water temperature difference value based on the correlation between the inlet and outlet water temperature difference and the reciprocal of the flow rate. The flow rate calculation unit 103 calculates a flow rate control value from the reciprocal of the flow rate. The flow rate calculation unit 103 notifies the rotation speed command unit 105 of the control value.

The rotation speed command section 105 is an example of a command means. The rotation speed command unit 105 commands the EWP 30 to change the rotation speed according to the flow rate control value.

A proportional relationship is established between the rotational speed of the EWP 30 and the flow rate of the cooling water, for example, based on a proportionality constant depending on the inlet water temperature. The rotation speed command unit 105 calculates the rotation speed of the EWP 30 based on the proportional relationship from the flow rate control value. As the cooling water inlet temperature, for example, the valve opening determination temperature of the thermostat 31 is used as a fixed value, but an estimated value calculated from the flow rate may also be used. Note that the rotation speed of the EWP 30 is an example of the output of the pump. The command to the EWP 30 is not limited to the number of revolutions, but may be a drive current value, for example.

Water temperature difference correction section 104 is an example of correction means. The water temperature difference correction unit 104 predicts at least one of the delay time and dead time of the response to the rotational speed command from the target flow rate according to the target value, and corrects the detected inlet and outlet water temperature difference based on the prediction result. Here, the water temperature difference correction unit 104 calculates a target flow rate from the target value of the inlet/outlet water temperature difference based on the correlation between the inlet/outlet water temperature difference and the reciprocal of the flow rate.

The flow rate calculation unit 103 calculates a flow rate control value from the water temperature difference detection value corrected by the water temperature difference correction unit 104. Therefore, the flow rate calculation unit 103 can assume at least one of a delay time and a dead time in response to a command according to a change in the target flow rate, and can reduce errors in the control value based on the assumption.

In the calorie map data table 130, for example, calorie parameters Kp are registered in advance in association with various detected values of the sensor system 4.

Kp=Qw/ρc...(1)

The calorific value parameter Kp is expressed, for example, by the above equation (1). In equation (1), the variable Qw indicates the amount of heat per unit time (J/s) that the cooling water receives from the engine 2, the constant ρ indicates the density of the cooling water (g/cm ³ ), and the constant c indicates the cooling water Shows the heat capacity (J/K) of water. The amount of heat parameter Kp is an example of a parameter related to the amount of heat that the cooling water receives from the engine 2.

The flow rate calculation unit 103 calculates the reciprocal of the flow rate from the inlet/outlet water temperature difference, using the rate of change of the temperature difference with respect to the reciprocal of the flow rate in the correlation between the inlet/outlet water temperature difference of the cooling water and the reciprocal of the flow rate as the calorific value parameter Kp. Therefore, the flow rate calculation unit 103 can appropriately calculate the reciprocal of the flow rate depending on the heat generation state of the engine 2. Similarly, the water temperature difference correction unit 104 also calculates the flow rate based on the temperature difference between the inlet and outlet of the cooling water using the heat value parameter Kp.

FIG. 3 is a diagram showing an example of the heat amount map data table 130. FIG. 3 shows a change in the calorific value parameter Kp with respect to the intake air amount (L/min.) of the engine 2.

As an example, the amount of intake air and the amount of heat parameter Kp are registered in advance in the heat amount map data table 130 in association with each other. The flow rate calculation unit 103 and the water temperature difference correction unit 104 refer to the heat quantity map data table 130 using, for example, the detected value of the intake pressure sensor 42 as the intake air quantity, and obtain the heat quantity parameter Kp corresponding to the intake air quantity.

(Correlation between cooling water flow rate and inlet/outlet water temperature difference)
FIG. 4 is a diagram showing an example of the correlation between the cooling water flow rate V (L/min.) and the inlet/outlet water temperature difference ΔTw (K) in a thermal equilibrium state. The characteristic Fr shows the correlation between the actual cooling water flow rate V and the inlet/outlet water temperature difference ΔTw, and the characteristic Fb shows the correlation between the cooling water flow rate V and the inlet/outlet water temperature difference ΔTw when there is no deviation α in the inlet water temperature of the cooling water due to disturbance. Show relationships. Further, the characteristic Fp indicates the correlation between the flow rate V of the cooling water and the difference in inlet/outlet water temperature ΔTw, which is assumed when the ECU 1 controls the flow rate V based on the characteristic Fb.

In each of the characteristics Fr, Fb, and Fp, a nonlinear relationship (substantially an inversely proportional relationship) is established between the cooling water flow rate V and the inlet/outlet water temperature difference ΔTw. Here, the proportionality constant is assumed to be the product (Vb×ΔTwb) of the predetermined flow rate Vb and the inlet/outlet water temperature difference ΔTwb in the characteristic Fp (see point Pc).

ΔTwact is a water temperature difference detection value obtained from the detection value of the outlet water temperature sensor 36, and Vact is a flow rate corresponding to the water temperature difference detection value ΔTwact in the characteristic Fr. ΔTwtgt is the target value of the inlet/outlet water temperature difference, and Vtgt is the target flow rate corresponding to the inlet/outlet water temperature difference ΔTwtgt at the specific Fp. Vcrc is the corrected flow rate to achieve the target inlet/outlet water temperature difference ΔTwtgt.

Here, the difference between the control target inlet and outlet water temperature difference ΔTwtgt and the inlet and outlet water temperature difference corresponding to the target flow rate Vtgt in characteristic Fb is set to γ, and the difference in each inlet and outlet water temperature difference corresponding to the target flow rate Vtgt in characteristics Fb and Fr is α shall be. Furthermore, the difference between the detected water temperature difference value ΔTwact and the inlet/outlet water temperature difference corresponding to the target flow rate Vtgt in the characteristic Fr is assumed to be ε. Therefore, the difference err between the inlet/outlet water temperature difference ΔTwtgt and the detected water temperature difference value ΔTwact is (α+γ+ε).

The flow rate Vcrc for controlling the inlet/outlet water temperature difference to the target inlet/outlet water temperature difference ΔTwtgt is calculated as follows.

Vcrc(ΔTwtgt-α)=Vact(ΔTwtgt+γ+ε)...(2)
Vcrc=Vact{(ΔTwtgt+γ+ε)/(ΔTwtgt−α)}
=Vact{1-err/(ΔTwtgt-α)} ...(3)

In the characteristic Fb, the above equation (2) holds true because the inlet/outlet water temperature difference and the multiplication value of the flow rate match each other for the point Pa corresponding to the flow rate Vact and the point Pb corresponding to the flow rate VCRC. The flow rate Vcrc is calculated by the equation (3) from the equation (2) and the above definition of the difference err.

In this way, when the flow rate V and the inlet/outlet water temperature difference ΔTw have a nonlinear relationship, it is difficult to compensate for the delay in response to flow rate control. If a control means that outputs the flow rate V from the inlet/outlet water temperature difference ΔTw is used, it is necessary to perform integral control (I control) using a nonlinear gain, which makes it difficult to perform control quickly and makes it vulnerable to disturbances.

Therefore, the flow rate calculation unit 103 controls the flow rate V based on the linear relationship between the reciprocal of the flow rate V and the inlet/outlet water temperature difference ΔTw instead of the nonlinear relationship between the flow rate V and the inlet/outlet water temperature difference ΔTw.

(Correlation between reciprocal of cooling water flow rate and inlet/outlet water temperature difference)
FIG. 5 is a diagram showing an example of the correlation between the reciprocal v (=1/V) (min./L) of the flow rate V of the cooling water and the inlet/outlet water temperature difference ΔTw (K). The characteristics fr, fb, and fp correspond to the characteristics Fr, Fb, and Fp in FIG. 4, respectively. Here, the slope of the straight line of each characteristic Fr, Fb, and Fp matches the above proportionality constant (Vb×ΔTwb). Further, regarding vcrc, vff, and vact, vcrc=1/Vcrc, vff=1/Vtgt, and vact=1/Vact hold true.

ΔTw=Vb×ΔTwb×v (4)

A linear relationship expressed by the above equation (4) is established between the reciprocal v of the cooling water flow rate V and the inlet/outlet water temperature difference ΔTw. Therefore, it becomes possible to treat the engine 2 and cooling system 3, which are plants to be controlled, as models with linear behavior.

ΔTw=Kp×v (5)

If the proportionality constant in equation (4), that is, the rate of change of the inlet/outlet water temperature difference ΔTw with respect to the reciprocal v of the flow rate V, is the above-mentioned calorific value parameter Kp, then the above-mentioned equation (5) holds true.

Therefore, when vcmd is the reciprocal of the control value Vcmd of the flow rate V, the water temperature difference detection value ΔTwact is expressed by the above equation (6) as a response of the plant. Here, 1/(Ts-1) represents the transfer function of the first-order lag element of the plant, and T is the time constant of the plant.

By treating the plant as a model with linear behavior in this way, the control system can be expressed by a transfer function, so the ECU 1 can compensate for a delay in the plant's response to flow rate control.

For example, by using the above correlation, the ECU 1 adjusts the control value Vcmd of the flow rate V based on the detected coolant temperature difference ΔTwact so as to compensate for the delay until the inlet/outlet water temperature difference ΔTw reaches the target value. It can be calculated. However, if the flow rate of the cooling water changes with a change in the target inlet/outlet water temperature difference ΔTwtgt, an error will occur in the control value Vcmd, so there is a risk that the outlet water temperature will overshoot and not converge quickly.

Therefore, the water temperature difference correction unit 104 predicts at least one of the delay time and dead time L of the response to the rotation speed command of the EWP 30 from the target flow rate Vtgt according to the target inlet and outlet water temperature difference ΔTwtgt, and uses the prediction result as Based on this, the detected water temperature difference value ΔTwact is corrected. In this example, the water temperature difference correction unit 104 predicts both the response delay time and dead time, but may predict only one of them.

The response delay time is calculated from the above time constant T. The time constant T is variable depending on the flow rate of cooling water. Therefore, the water temperature difference correction unit 104 and the flow rate calculation unit 103 read the time constant T from the time constant data table 131 based on the target flow rate Vtgt.

FIG. 6 is a diagram showing an example of the time constant data table 131. In the time constant data table 131, a flow rate (L/min.) and a time constant T (ms) are registered in association with each other. As an example, the time constant T decreases linearly as the flow rate increases. Note that the time constant data table 131 is stored in advance in the storage memory 13 based on the results of experiments and simulations.

The flow rate calculation unit 103 calculates a time constant T according to the target flow rate Vtgt using the time constant data table 131, and compensates for a delay in the response of the plant to flow rate control based on the time constant T. Therefore, the flow rate calculation unit 103 can use an appropriate time constant T according to the change in flow rate when compensating for the delay.

Further, the water temperature difference correction unit 104 calculates a time constant T according to the target flow rate Vtgt using the time constant data table 131, and predicts the delay time of the response of the plant to the flow rate control from the time constant T. Therefore, the water temperature difference correction unit 104 can use an appropriate time constant T according to the change in flow rate when predicting the delay time.

Further, like the time constant T, the dead time L is also variable depending on the flow rate of the cooling water. Therefore, the water temperature difference correction unit 104 and the flow rate calculation unit 103 read the dead time L from the dead time data table 132 based on the target flow rate.

FIG. 7 is a diagram showing an example of the dead time data table 132. In the dead time data table 132, flow rate (L/min.) and dead time L (ms) are registered in association with each other. As an example, an inversely proportional relationship holds between the dead time L and the flow rate. Note that the dead time data table 132 is stored in advance in the storage memory 13 based on the results of experiments and simulations.

In this way, the time constant T and the dead time L are variable depending on the flow rate. The flow rate here is the volumetric flow rate of the cooling water that passes through the entire engine 2, and is a factor that determines heat transport and heat transfer speed by the cooling water. Therefore, the water temperature difference correction unit 104 and the flow rate calculation unit 103 estimate the delay time and dead time L for the rotation speed command according to the control value Vcmd with high precision from the target flow rate Vtgt, and calculate the expected response from the command. As a correction amount, a correction value of the water temperature difference detection value ΔTwact is calculated from the estimation result.

The flow rate calculation unit 103 corrects the target inlet/outlet water temperature difference ΔTwtgt using the corrected water temperature difference detection value ΔTwact. Thereby, the flow rate calculation unit 103 can reflect the response delay and dead time L of the plant in the control value Vcmd.

The water temperature difference correction unit 104 calculates the convergent water temperature difference from the dead time L based on the convergent water temperature difference data table 133. The convergence water temperature difference is the post-convergence inlet/outlet water temperature difference ΔTw that is assumed from the current flow rate V, and is obtained as a history of the past inlet/outlet water temperature difference ΔTw that goes back by a dead time L from the current time when the control process is executed. be done. The water temperature difference correction unit 104 records the history of the inlet/outlet water temperature difference ΔTw in the converged water temperature difference data table 133 in time series at each predetermined cycle of the control process.

FIG. 8 is a diagram showing an example of the convergent water temperature difference data table 133. In the convergent water temperature difference data table 133, convergent water temperature differences D[0] to D[N] (K) (N: an integer of 2 or more), which are the latest N past inlet/outlet water temperature differences ΔTw, are registered. There is.

The convergent water temperature difference D[0] is the latest inlet/outlet water temperature difference ΔTw, and the convergent water temperature difference D[N] is the oldest inlet/outlet water temperature difference ΔTw. The convergent water temperature difference D[0] is the value at the current time Tp when the control process is performed, and the convergent water temperature difference D[1] is the value at the time (Tp-1×f ), and the convergent water temperature difference D[N] is the value at a time (Tp−N×f) that is N times the control processing period f before the current time Tp. Note that the initial values of the convergent water temperature differences D[0] to D[N] are not limited, but may be set based on, for example, the flow rate in response to feedforward control based on the target value of the outlet water temperature.

The water temperature difference correction unit 104 updates the latest converged water temperature difference D[0] to the inlet and outlet water temperature difference ΔTw based on the current flow rate V of the cooling water every cycle f of the control process. In addition, the water temperature difference correction unit 104 updates the remaining convergent water temperature differences D[1] to D[N] to the convergent water temperature differences D[0] to D[N-1] before updating. In other words, the water temperature difference correction unit 104 shifts each value of the converged water temperature differences D[0] to D[N-1] by one every cycle f of the control process.

The water temperature difference correction unit 104 determines the dead time L from the dead time data table 132, and refers to the convergent water temperature difference data table 133 based on the dead time L. Thereby, the water temperature difference correction unit 104 obtains the convergent water temperature difference according to the time (Tp-i×f) (i=1, 2, . . . , N) before the current time Tp by the dead time L. .

At this time, the water temperature difference correction unit 104 can calculate the array number i of the convergent water temperature differences D[1] to D[N] by dividing the dead time L by the cycle f of the control process, for example. Specifically, the water temperature difference correction unit 104 calculates the value of the integer part of L/f as the array number i. For example, when L/f=5.3, the array number i corresponding to the dead time L is "5", and the convergent water temperature difference D[5] is obtained (see the dotted frame).

In this way, the water temperature difference correction unit 104 records the history of the inlet and outlet water temperature difference ΔTw of the cooling water in time series in the convergent water temperature difference data table 133 as a response to the rotation speed command according to the flow rate control value Vcmd, A value of the dead time L before is obtained from the converged water temperature difference data table 133 and used for correcting the detected water temperature difference value ΔTwact. Therefore, the water temperature difference correction unit 104 can highly accurately correct the detected water temperature difference value ΔTwact based on the history of the entrance and exit water temperature difference ΔTw. Note that the water temperature difference correction unit 104 is not limited to this, and may calculate the convergent water temperature difference from the dead time L using an approximate formula or the like.

In addition, the water temperature difference correction unit 104 converges the history of the inlet and outlet water temperature difference ΔTw in a time series based on the above correlation between the inlet and outlet water temperature difference ΔTw and the reciprocal number v of the flow rate V from the current flow rate V of the cooling water. It is recorded in the data table 133. That is, the water temperature difference correction unit 104 calculates the inlet/outlet water temperature difference ΔTw from the current flow rate V of the cooling water using the above equation (5). Therefore, the water temperature difference correction unit 104 is able to reduce errors caused by saturation or delay of the control value Vcmd due to actual plant characteristics, compared to calculating the inlet/outlet water temperature difference ΔTw from the control value Vcmd. can.

Further, the water temperature difference correction unit 104 calculates the current flow rate V based on the rotation speed acquired from the rotation speed sensor 44 by the detection value acquisition unit 101 from the above proportional relationship between the rotation speed of the EWP 30 and the cooling water flow rate V. Estimate. Therefore, the water temperature difference correction unit 104 can obtain the current flow rate V and record the history of the inlet/outlet water temperature difference ΔTw without requiring a detection means for detecting the flow rate V such as a flow meter.

(Block diagram)
FIG. 9 is a block diagram showing an example of a feedback control system of the plant P. The feedback control system includes transfer elements of transfer functions F, Pn ⁻¹ , LIM, and Pn. Here, each process of the transfer functions F, Pn ⁻¹ and LIM is executed by the flow rate calculation unit 103, and the process of the transfer function Pn and the process of calculating the feedback water temperature difference ΔTwfb from the detected water temperature difference value ΔTwact are executed by the water temperature difference correction unit 104. Executed by

Pn ⁻¹ = (Ts+1)/Kp (7)
Pn=Kp・e ^-Ls /(Ts+1)...(8)

The transfer function Pn ^-1 is expressed by the above equations (6) to (7) based on the linear relationship between the inverse number v of the flow rate V and the inlet/outlet water temperature difference ΔTw. Further, the transfer function Pn is expressed by the above equation (8). Note that the transfer element of the transfer function Pn ^-1 is expressed as an "inverse plant model," and the transfer element of the transfer function Pn is expressed as a "plant response assumption model."

Regarding the inverse plant model, the transfer function Pn ^-1 outputs a control value vcmd (=1/Vcmd) of the reciprocal of the cooling water flow rate to compensate for the first order lag element of the response of the plant P. The time constant T in equation (7) is determined from the time constant data table 131 as described above, and is used as a linear advance element. Thereby, the inverse plant model compensates for the delay until the inlet/outlet water temperature difference ΔTw reaches the target inlet/outlet water temperature difference ΔTwtgt.

However, the inverse plant model cannot perform retroactive compensation for the dead time L minutes due to causality. Therefore, the dead time L is handled using a plant response assumption model. The transfer function Pn outputs an assumed inlet/outlet water temperature difference ΔTwcmd based on the first-order delay element and dead time element of the response of the plant P from the control value vcmd.

Regarding the plant response assumed model, as described above, the water temperature difference correction unit 104 obtains the assumed inlet/outlet water temperature difference ΔTwcmd by estimating the response delay and dead time L from the target flow rate Vtgt. Examples of the dead time L of the plant P include, but are not limited to, a delay time in calculating the detected value Tout of the outlet water temperature sensor 36 and a delay time in transporting cooling water. The time constant T in equation (8) is determined from the time constant data table 131 as described above, and is used as a first-order delay element. The dead time L is also determined from the time constant data table 131 and is used as a primary advance element.

The water temperature difference detection value ΔTwact, which is the response of the plant, is reduced by the assumed inlet/outlet water temperature difference ΔTwcmd calculated by the plant response assumption model before being fed back. In this way, the water temperature difference correction unit 104 predicts the response delay and dead time L of the plant P from the target flow rate Vtgt, and corrects the detected water temperature difference value ΔTwact based on the prediction result.

Therefore, the flow rate calculation unit 103 can reduce the response delay of the plant P and the deviation of the response delay assumed by the inverse plant model, and reduce the influence of the dead time L to calculate an appropriate control value Vcmd. . This absorbs disturbances and modeling errors and improves the stability and responsiveness of flow control.

The flow rate calculation unit 103 determines a target inlet/outlet water temperature difference ΔTwtgt based on various detected values of the sensor system 4, for example. The control target inlet/outlet water temperature difference ΔTwtgt is subtracted by the corrected water temperature difference detection value ΔTwact' and is input to the transfer element of the transfer function F as the feedback water temperature difference ΔTwfb. Further, the water temperature difference correction unit 104 calculates the target flow rate Vtgt from the above-mentioned correlation between the reciprocal v of the cooling water flow rate V and the inlet/outlet water temperature difference ΔTw from the target inlet/outlet water temperature difference ΔTwtgt.

F=1/(T _F s+1) ... (9)

The transfer function F corresponds to a low-pass filter, and is expressed, for example, by the above equation (9). Here, T _F is the time constant of the low-pass filter. The feedback water temperature difference ΔTwfb is filtered by the transfer function F before being input to the inverse plant model. That is, the flow rate calculation unit 103 performs filtering processing using a low-pass filter on the feedback water temperature difference ΔTwfb.

Therefore, fluctuations in the feedback water temperature difference ΔTwfb due to noise or the like are suppressed. Therefore, variations in the control value Vcmd are suppressed and stability of flow rate control is improved. Note that this filtering process may not be provided if the fluctuation in the feedback water temperature difference ΔTwfb is sufficiently small.

Further, the transfer function LIM limits the control value Vcmd depending on the state of the cooling system 3. By the transfer function LIM, for example, a lower limit value of the flow rate when determining whether to open the on-off valve 311 of the thermostat 31 or a lower limit value of the flow rate for preventing boiling of the cooling water in the drill path of the water jacket 23 is set.

(ECU flow rate control operation)
FIG. 10 is a flowchart showing an example of the flow rate control operation of the ECU 1. The following operation is an example of a control method.

First, the detected value acquisition unit 101 acquires each detected value from the outlet water temperature sensor 36 and the sensor system 4 (step St1). Next, the flow rate calculation unit 103 obtains the calorific value parameter Kp by referring to the calorific value map data table 130 based on the detected value of the intake air amount among the detected values of the sensor system 4 (step St2). Next, the flow rate calculation unit 103 determines a target value To of the outlet water temperature (target outlet water temperature) based on each detection value of the sensor system 4 (step St3).

ΔTwtgt=To-Tin...(10)

Next, the flow rate calculation unit 103 calculates the target inlet/outlet water temperature difference ΔTwtgt from the above equation (10) (Step St4). Although Tin is a predetermined inlet water temperature here, it may be an estimated value of the inlet water temperature as described later.

ΔTwact=Tout-Tin...(11)

Next, the flow rate calculation unit 103 calculates the detected water temperature difference value ΔTwact from the above equation (11) (Step St5). Here, Tout is a detection value of the outlet water temperature sensor 36. Further, since the inlet water temperature Tin is a fixed value, the control process is easier than when estimating the inlet water temperature Tin from the flow rate V, for example. When the inlet water temperature Tin is a fixed value, a deviation in the outlet water temperature due to an error between the inlet water temperature Tin and the actual inlet water temperature is absorbed as a deviation by the control value vcmd of the feedback control like a disturbance.

ΔTwcmd=Pn・vcmd (12)

Next, the water temperature difference correction unit 104 calculates an assumed inlet/outlet water temperature difference ΔTwcmd from the control value vcmd calculated in step St9, which will be described later, and the transfer function Pn of the plant response assumption model, according to the above equation (12) (step St6). . Thereby, the water temperature difference correction unit 104 predicts the response delay and dead time L of the plant P until the detected water temperature difference value ΔTwact reaches the target inlet/outlet water temperature difference ΔTwtgt. Specifically, the water temperature difference correction unit 104 makes a prediction using the target flow rate Vtgt, and the details of the process will be described later.

ΔTwact’=ΔTwact−ΔTwcmd (13)

Next, the water temperature difference correction unit 104 calculates the corrected water temperature difference detection value ΔTwact' from the difference between the water temperature difference detection value ΔTwact and the assumed inlet/outlet water temperature difference ΔTwcmd according to the above equation (13) (Step St7). In this manner, the water temperature difference correction unit 104 corrects the water temperature difference detection value ΔTwact based on the predicted response delay and dead time L of the plant P.

ΔTwfb=ΔTwtgt−ΔTwact' (14)

Next, the flow rate calculation unit 103 calculates the feedback water temperature difference ΔTwfb from the difference between the target inlet/outlet water temperature difference ΔTwtgt and the corrected water temperature difference detection value ΔTwact' according to the above equation (14) (Step St8).

vcmd=F・Pn ^-1・ΔTwfb...(15)

Next, the flow rate calculation unit 103 calculates the control value vcmd of the reciprocal of the flow rate V from the transfer functions Pn ⁻¹ , F of the inverse plant model and the low-pass filter, and the feedback water temperature difference ΔTwfb according to the above equation (15) (step St9).

Next, the flow rate calculation unit 103 calculates a control value Vcmd (=1/vcmd) of the flow rate V from the control value vcmd (Step St10). Next, the rotation speed command unit 105 calculates a command value Rcmd of the rotation speed of the EWP 30 from the control value Vcmd (step St11). The command value Rcmd is calculated by, for example, Kc·Vcmd, where Kc is a proportionality constant. Next, the rotation speed command unit 105 commands the EWP 30 to give a command value Rcmd (step St12). In this manner, the rotation speed command unit 105 commands the pump to specify the rotation speed command value Rcmd in accordance with the control value Vcmd.

Next, the flow rate calculation unit 103 determines whether or not it has received an instruction to end the flow rate control from the operation control unit 100 (Step St13). If the flow rate calculation unit 103 has not received the termination instruction (No in step St13), the operations from step St1 onwards are executed again. Further, if the flow rate calculation unit 103 has received the termination instruction (Yes in step St13), this operation is terminated.

In this way, the ECU 1 controls the flow rate V of the cooling water circulating through the water jackets 20 and 23 of the engine 2. The detected value acquisition unit 101 acquires the detected value Tout of the outlet water temperature of the water jacket 20. The flow rate calculation unit 103 calculates a control value Vcmd based on the detected water temperature difference value ΔTwact so as to compensate for the delay until the cooling water inlet/outlet water temperature difference ΔTw reaches the target inlet/outlet water temperature difference ΔTwtgt.

FIG. 11 is a flowchart illustrating an example of a calculation process of the assumed inlet/outlet water temperature difference ΔTwcmd. This process is executed in step St6 above.

Vtgt=Pn ^-1・ΔTwtgt...(16)

The water temperature difference correction unit 104 calculates the target flow rate Vtgt from the target inlet/outlet water temperature difference ΔTwtgt according to the above equation (16) based on the above correlation between the reciprocal number v of the flow rate V and the inlet/outlet water temperature difference ΔTw (step St21).

Next, the water temperature difference correction unit 104 determines the dead time L according to the target flow rate Vtgt by referring to the dead time data table 132 based on the target flow rate Vtgt (step St22). Thereby, the water temperature difference correction unit 104 can obtain an appropriate dead time L according to the target flow rate Vtgt achieved by the control value Vcmd.

Next, the water temperature difference correction unit 104 calculates the array number i (=L/f) of the convergent water temperature difference data table 133 from the cycle f and dead time L of this process (step St23). Next, the water temperature difference correction unit 104 obtains the convergent water temperature difference D[i] according to the array number i from the convergent water temperature difference data table 133 (Step St24). The convergent water temperature difference D[i] corresponds to the value obtained by multiplying Kp·e ^−Ls in the above equation (8) by the reciprocal vcmd of the control value Vcmd.

In this way, the water temperature difference correction unit 104 obtains the value of the dead time L before from the history of the inlet/outlet water temperature difference ΔTw. Therefore, the water temperature difference correction unit 104 can estimate the inlet/outlet water temperature difference ΔTw with high precision from the past history, taking into account the influence of the dead time L.

Next, the water temperature difference correction unit 104 acquires the rotation speed of the EWP 30 by the detected value acquisition unit 101 (Step St25). Next, the water temperature difference correction unit 104 estimates the current flow rate V from the rotation speed of the EWP 30 based on the correlation between the rotation speed and the flow rate V (step St26). Therefore, the water temperature difference correction unit 104 can obtain the current flow rate V without requiring a detection means for detecting the flow rate V, such as a flow meter.

Next, the water temperature difference correction unit 104 estimates the inlet/outlet water temperature difference ΔTw from the reciprocal number v of the current flow rate V according to the above equation (5) (Step St27).

Next, the water temperature difference correction unit 104 updates the convergent water temperature differences D[0] to D[N] in the convergent water temperature difference data table 133 (Step St28). At this time, the water temperature difference correction unit 104 updates the convergent water temperature differences D[1] to D[N] to the convergent water temperature differences D[0] to D[N-1], and converts the convergent water temperature differences D[0] into Update to the estimated inlet/outlet water temperature difference ΔTw. Therefore, in the convergent water temperature difference data table 133, the history of the latest N inlet/outlet water temperature differences ΔTw is always recorded as convergent water temperature differences D[0] to D[N].

In this way, the water temperature difference correction unit 104 converges the history of the inlet/outlet water temperature difference ΔTw in time series from the current flow rate V of the cooling water based on the above correlation between the reciprocal number v of the flow rate V and the inlet/outlet water temperature difference ΔTw. It is recorded in the water temperature difference data table 133.

Next, the water temperature difference correction unit 104 determines a time constant T according to the target flow rate Vtgt by referring to the time constant data table 131 based on the target flow rate Vtgt (step St29). Thereby, the water temperature difference correction unit 104 can obtain an appropriate time constant T according to the target flow rate Vtgt achieved by the control value Vcmd.

ΔTwcmd=D[i]/(Ts+1) (17)

Next, the water temperature difference correction unit 104 calculates the assumed inlet/outlet water temperature difference ΔTwcmd from the converged water temperature difference D[i] and the time constant T according to the above equation (17) (Step St30). Equation (17) is based on Equations (12) and (8) above. The water temperature difference correction unit 104 corrects the detected water temperature difference value ΔTwact based on the assumed inlet/outlet water temperature difference ΔTwcmd, as described above. Thereby, the target inlet/outlet water temperature difference ΔTwtgt is corrected to the feedback water temperature difference ΔTwfb by the detected water temperature difference value ΔTwact, so that the flow rate calculation unit 103 can calculate an appropriate control value Vcmd.

(Example of controlling outlet water temperature)
FIG. 12 is a diagram showing temporal changes in outlet water temperature in a comparative example. In this example, a case will be described in which the plant response assumption model does not assume the response delay and dead time L of the plant P. FIG. 12 shows the target value of the outlet water temperature corresponding to the target inlet/outlet water temperature difference ΔTwtgt, the command value of the outlet water temperature corresponding to the control value Vcmd, the assumed value of the outlet water temperature corresponding to the assumed inlet/outlet water temperature difference ΔTwcmd, and the flow control value. The actual water temperature of the outlet water temperature as a response is shown.

If the dead time L is not assumed, the assumed value increases to substantially the same time as the target value. The actual water temperature starts to rise in accordance with the command value after a delay of the dead time τ, but because of the deviation A1 from the assumed value, control is performed to increase the actual water temperature excessively. This causes the actual water temperature to exceed the target value and overshoot. Note that T1 is the peak value T1 of the command value.

FIG. 13 is a diagram showing temporal changes in outlet water temperature in the example. In this example, a case will be described in which the plant response assumption model assumes a dead time L of the plant P. Note that in FIG. 13, explanations of parameters common to those in FIG. 12 will be omitted.

The assumed value increases with a delay from the target value increase timing due to the transfer function Pn by assuming a dead time L (see symbol X). Further, the command value is kept lower than in the comparative example, depending on the delay of the estimated delay value. Specifically, the peak value T2 of the command value is lowered by ΔT than the peak value T1 of the command value in the comparative example due to the convergence water temperature difference D[i] obtained from the dead time L.

In addition, the actual water temperature starts to rise with a delay from the timing when the command value starts rising, but this delay is close to the dead time L, so as shown by arrow A2, the actual water temperature that exceeds the target value is It acts to lower it. Therefore, the control timing and the response timing have an appropriate relationship. Therefore, the overshoot of the actual water temperature is suppressed to be significantly lower than in the comparative example.

In this way, the water temperature difference correction unit 104 appropriately adjusts the control value Vcmd (vcmd) and the relationship between the control timing and the response timing by predicting the delay including the dead time L in response to flow rate control. be done.

Pn=Kp・e ^-Ls ...(8a)
Pn=Kp/(Ts+1)...(8b)

Note that, as in this example, the transfer function Pn when only the dead time L is assumed is expressed by the above equation (8a). On the other hand, the transfer function Pn when only the response delay of the plant to control is assumed is expressed by the above equation (8b). Even when the transfer function Pn of equation (8b) is used, the same effect as described above can be obtained.

The embodiments described above are examples of preferred implementations of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

1 ECU (computer)
2 Engine (internal combustion engine)
9 Control system 10 CPU
20, 23 Water jacket (cooling channel)
21, 22 Outlet 24 Inlet 30 EWP (pump)
31 Thermostat 32 Radiator 36 Outlet water temperature sensor 37 EGR channel 38 Distribution channel 101 Detected value acquisition unit (acquisition means)
103, 103a Flow rate calculation unit (calculation means)
104 Water temperature difference correction section (correction means)
105 Rotation speed command section (command means)
380 ATF flow path 381 Heater flow path 382 Radiator flow 390,391 Return flow path 130 Heat map data table 131 Time constant data table 132 Dead time data table 133 Convergence water temperature difference data table

Claims (14)

In a control device that controls the flow rate of a cooling medium circulating through a cooling channel of an internal combustion engine,
acquisition means for acquiring a detected value of the temperature of the cooling medium at the outlet of the cooling channel;
Compensating for a delay until the temperature difference of the cooling medium at the inlet and outlet of the cooling channel reaches a target value based on the difference between the temperature of the cooling medium at the inlet of the cooling channel and the detected value. Calculation means for calculating the control value of the flow rate;
command means for commanding a pump that circulates the cooling medium into the cooling flow path to output according to the control value;
a correction means for predicting at least one of a delay time and a dead time in response to the output command from a target flow rate according to the target value, and correcting the difference based on the prediction result;
Control device. The correction means records the history of the temperature difference of the cooling medium in chronological order as a response to the output command, obtains a value from the history of the temperature difference by the dead time, and corrects the difference. used for
The control device according to claim 1. The correction means records the history of the temperature difference in time series from the current flow rate of the cooling medium based on the correlation between the temperature difference and the reciprocal of the flow rate.
The control device according to claim 2. The acquisition means acquires the rotation speed of the pump,
the correction means estimates the current flow rate of the cooling medium from the rotational speed;
The control device according to claim 3. The correction means calculates a time constant according to the target flow rate, and predicts the delay time from the time constant.
A control device according to any one of claims 1 to 4. The calculation means calculates a time constant according to the target flow rate, and compensates for a delay based on the time constant.
A control device according to any one of claims 1 to 4. The calculation means calculates the control value by setting the temperature of the cooling medium at the inlet of the cooling channel as a fixed value.
A control device according to any one of claims 1 to 4. In a control method for controlling the flow rate of a cooling medium circulating through a cooling channel of an internal combustion engine,
obtaining a detected value of the temperature of the cooling medium at the outlet of the cooling channel;
Compensating for a delay until the temperature difference of the cooling medium at the inlet and outlet of the cooling channel reaches a target value based on the difference between the temperature of the cooling medium at the inlet of the cooling channel and the detected value. Calculating the control value of the flow rate,
commanding a pump that circulates the cooling medium through the cooling flow path to output according to the control value;
A computer executes a process of predicting at least one of a delay time and dead time of a response to the output command from a target flow rate according to the target value, and correcting the difference based on the prediction result.
Control method. In the process of correcting the difference based on the prediction result, as a response to the output command, the history of the temperature difference of the cooling medium is recorded in chronological order, and the history of the temperature difference is corrected by the dead time. and use it to correct the difference,
The control method according to claim 8. In the process of correcting the difference based on the prediction result, a history of the temperature difference is recorded in chronological order from the current flow rate of the cooling medium based on a correlation between the temperature difference and the reciprocal of the flow rate.
The control method according to claim 9. In the process of correcting the difference based on the prediction result, obtaining the rotation speed of the pump, and estimating the current flow rate of the cooling medium from the rotation speed.
The control method according to claim 10. In the process of correcting the difference based on the prediction result, calculating a time constant according to the target flow rate, and predicting the delay time from the time constant.
The control method according to any one of claims 8 to 11. In the process of calculating the control value of the flow rate, calculating a time constant according to the target flow rate, and compensating for a delay based on the time constant.
The control method according to any one of claims 8 to 11. In the process of calculating the control value of the flow rate, the control value is calculated by setting the temperature of the cooling medium at the inlet of the cooling channel as a fixed value.
The control method according to any one of claims 8 to 11.

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