JP2013044230A - Cooling control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness of control of cooling water temperature, in a cooling system of an internal combustion engine, which has a control valve such as an electronically-controlled thermostat and which controls the cooling water temperature depending on an engine operation state.SOLUTION: A cooling control device of the internal combustion engine 1 includes: a water pump 2; a cooling water circuit 4 which circulates cooling water, discharged from the water pump 2, between the internal combustion engine 1 and a radiator 3; a bypass channel 43 which bypasses the radiator 3; the control valve 44; and a control unit 5. When increasing the cooling water temperature, the control unit 5 controls the water pump 2 so as to reduce a discharge amount, and controls the control valve 44 so as to increase a flow rate of the cooling water bypassing the radiator 3. In addition, when decreasing the cooling water temperature, the control unit 5 controls the water pump 2 so as to increase the discharge amount, and controls the control valve 44 so as to increase the flow rate of the cooling water passing through the radiator 3.

Description

  The present invention relates to a cooling control device for an internal combustion engine, and more particularly to a cooling control device for an internal combustion engine that controls the temperature of cooling water in accordance with the engine operating state.

  In recent years, in an internal combustion engine cooling system for a vehicle, an electronically controlled thermostat valve “hereinafter simply referred to as“ electricity ”is used in order to reduce fuel consumption and improve output by controlling the temperature of cooling water according to engine operating conditions. “Thermostat” is often adopted. The valve opening of the electric control thermostat does not depend only on the temperature of the cooling water, but can be arbitrarily changed by a control signal, and is provided in the middle of the cooling water circulation path for circulating the cooling water. And the flow rate of the cooling water which passes a radiator and the flow rate of the cooling water which bypasses a radiator are changed by adjusting the valve opening degree of an electric control thermostat.

  By the way, in the cooling system of an internal combustion engine using such an electric control thermostat, it has been conventionally required to improve the responsiveness of the temperature control of the cooling water, and several proposals have been made so far. . For example, Patent Document 1 discloses a technique for controlling an electric thermostat by determining an operation amount of the electric thermostat by monitoring only an actual cooling water temperature. Patent Document 2 calculates the elapsed time from the output of the operation amount to the electric thermostat to the control water temperature and the amount of change in water temperature per unit time, and the cooling water temperature after the elapsed time is calculated from these. A technique for predicting and controlling an electric thermostat in accordance with the predicted cooling water temperature is disclosed.

JP 2004-353602 A JP 2004-137981 A

  However, the response delay of the temperature control includes an operation delay of the electric thermostat, that is, a delay until the valve opening changes after the operation amount is input. It cannot be said that the delay in operation is sufficiently eliminated, and there is room for further improvement in this respect.

  The present invention has been made paying attention to such a situation, and has a control valve such as the above-mentioned electric control thermostat, and in a cooling system of an internal combustion engine that controls the temperature of cooling water according to the engine operating state. An object of the present invention is to improve the responsiveness of the temperature control of the cooling water as compared with the conventional case.

  An internal combustion engine cooling control device according to an aspect of the present invention is a cooling control device for an internal combustion engine that controls the temperature of cooling water in accordance with an engine operating state, the water pump capable of changing a discharge amount, and the water pump. A cooling water circulation path for circulating cooling water discharged from the internal combustion engine and the radiator, a bypass flow path for bypassing the radiator, a cooling water for passing the radiator, and a flow rate of the cooling water for bypassing the radiator A control valve capable of changing distribution, and a control unit for controlling the water pump and the control valve, wherein the control unit reduces the discharge amount when the temperature of the cooling water is increased. The control valve is controlled to increase the flow rate of cooling water that controls the water pump and bypasses the radiator. When the temperature of the cooling water is decreased, the water pump is controlled to increase the discharge amount and the control valve is controlled to increase the flow rate of the cooling water that passes through the radiator. .

  According to the cooling control apparatus for an internal combustion engine, when the temperature of the cooling water is increased or decreased, not only the control valve but also the water pump is controlled. This can be compensated for by increasing or decreasing the amount, and the temperature control response of the cooling water is improved.

It is a figure which shows schematic structure of the internal combustion engine and its cooling control apparatus by one Embodiment of this invention. It is a figure which shows the valve characteristic (valve opening degree in each water temperature in the maximum operation amount (DUTY100%) and the minimum operation amount (DUTY0%)) of a control valve. It is a flowchart which shows the control about a control valve. It is a figure which shows the valve characteristic (valve opening degree with respect to the output time of the maximum operation amount (DUTY100%) and the minimum operation amount (DUTY0%)) of a control valve. It is a figure for demonstrating the correction amount (DELTA) DUTY of the operation amount for absorbing this steady deviation when a steady deviation is large. It is a timing chart of transient control about a control valve. It is a flowchart which shows the control about a water pump. It is a timing chart of the transient control about a water pump.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration of a vehicle internal combustion engine 1 and its cooling control device according to an embodiment of the present invention. The cooling control device for the internal combustion engine 1 includes a water pump (W / P) 2 capable of changing a flow rate (discharge amount), and cooling water discharged from the water pump 2 passes through the internal combustion engine 1 (water jacket). A circulation path 4 that returns to the water pump 2 via the radiator 3 and a controller 5 that controls the operation of each component of the cooling control device are included.
Here, as shown by a broken line in FIG. 1, the second circulating water in which the cooling water that has passed through the internal combustion engine 1 returns to the water pump 2 via a continuously variable transmission (CVT) 6 connected to the internal combustion engine 1. The cooling water that has passed through the path and the internal combustion engine 1 may further include a third circulation path that returns to the water pump 2 via the heater core 7 for heating used for in-vehicle air conditioning.

  The water pump 2 operates using electric power supplied from an in-vehicle battery (not shown) as a power source, and an electric water pump that can change the pump rotation speed (that is, discharge amount) by a control signal (energization duty) from the control unit 5. It is. However, the pump is not limited to the electric water pump, and any pump that can change the flow rate (discharge amount) by a control signal from the control unit 5 may be used. For example, a mechanical variable displacement water pump that can change the flow rate (discharge amount) by ON / OFF of an electromagnetic clutch may be used.

  The radiator 3 dissipates heat absorbed by the cooling water circulating in the circulation path 4 from the cylinder head 11 and the cylinder block 12. The radiator 3 is provided with a radiator fan (not shown). The radiator fan is activated when the cooling water needs to be cooled, and assists the heat dissipation from the cooling water in the radiator 3.

The circulation path 4 includes a cooling water outlet 11 a provided on the cylinder head 11 side of the internal combustion engine 1 and a cooling water inlet portion 3 a of the radiator 3, and a cooling water outlet portion 3 b of the radiator 3. And a second coolant passage 42 connecting the coolant inlet 12a provided on the cylinder block 12 side of the internal combustion engine 1. The circulation path 4 is provided with a bypass flow path 43 that bypasses the radiator 3, and a control valve 44 is provided at a junction between the bypass flow path 43 and the second cooling water flow path 42.
The control valve 44 is an electric thermostat provided with a heat generating element in the temperature sensing part of the thermostat, and the valve opening degree does not depend only on the temperature of the cooling water, but by the energization control to the heat generating element by the control part 5. The valve opening can be changed. However, the present invention is not limited to the electric thermostat, and any valve can be used as long as the valve opening can be changed by a control signal from the controller 5.

  FIG. 2 shows the valve characteristics of the control valve (electrically controlled thermostat) 44 in the present embodiment. The horizontal axis is the cooling water temperature, and the vertical axis is the valve opening (lift amount). In FIG. 2, the solid line indicates the case where the operation amount of the control valve 44 is the maximum, that is, the energization duty for the heating element by the control unit 5 is 100%, and the broken line indicates the operation amount of the control valve 44 is the minimum, The case where the electricity supply duty with respect to the said heat generating element by the control part 5 is 0% is shown.

  As shown in FIG. 2, in this embodiment, if the control valve 44 does not energize the heat generating element (that is, the energization duty is 0%), the temperature of the cooling water is about 100 ° C. or higher. Although the valve is not opened until it becomes, it can be opened even if the temperature of the cooling water is about 100 ° C. or less by energizing the heating element. Specifically, in this embodiment, the control valve 44 can be opened from the temperature of the cooling water of about 40 ° C. by energizing the heat generating element.

  Here, when the control valve 44 is closed, the cooling water that has passed through the internal combustion engine 1 passes through the bypass flow path 43 without passing through the radiator 3, and the control valve 44 is opened, whereby the internal combustion engine. The cooling water that has passed through 1 passes through the radiator 5. Then, the control unit 5 adjusts the operation amount to the control valve 44, that is, the energization duty with respect to the heating element to adjust the valve opening degree of the control valve 44, so that the cooling water and the radiator passing through the radiator 3 are adjusted. The flow distribution with the cooling water that bypasses 3 can be changed. Specifically, the flow rate (distribution) of the cooling water that passes through the radiator 3 increases as the valve opening degree of the control valve 44 increases, and the cooling water that bypasses the radiator 3 as the opening degree of the control valve 44 decreases. The flow rate (distribution) increases.

  The control unit 5 inputs the vehicle speed and the engine load (for example, accelerator opening degree and intake air amount) of a vehicle on which the internal combustion engine 1 is mounted as operating state information of the internal combustion engine 1, and the cylinder head 11 (water jacket). Detection signals are input from various sensors such as a water temperature sensor 61 that detects the temperature of the cooling water inside, an outside air temperature sensor 62 that detects the temperature of outside air, and a knock sensor 63 that detects the occurrence of knocking. And the control part 5 controls the action | operation of the water pump 2 and the control valve 44 based on the various information input. As the outside air temperature sensor 62, an intake air temperature sensor can be used.

Next, the control of the water pump (electric water pump) 2 and the control valve (electric control thermostat) 44 executed by the control unit 5 will be described.
The control unit 5 inputs an engine operating state (here, vehicle speed and engine load), and sets a target temperature of cooling water (hereinafter referred to as “target water temperature”) based on the input engine operating state. Then, the water pump 2 and the control valve 44 are controlled based on the set target water temperature.
Hereinafter, control for the control valve 44 will be described first, and then control for the water pump 2 will be described.

FIG. 3 is a flowchart showing control of the control valve 44 executed by the control unit 5.
In FIG. 3, in step S1, whether or not the amount of change in the target water temperature is greater than or equal to a preset threshold (for example, 5 ° C.), that is, the operating state (vehicle speed, engine load) of the internal combustion engine 1 has changed. It is determined whether or not the deviation (absolute value) between the target water temperature and the coolant temperature detected by the water temperature sensor 61 (hereinafter referred to as “actual water temperature”) is equal to or greater than the threshold value. And if the variation | change_quantity of target water temperature is more than the said threshold value, it will progress to step S2 in order to perform transient control.
In step S2, it is determined whether the target water temperature has changed from a high side to a low side. If the target water temperature has changed from the higher side to the lower side, the process proceeds to step S3.

In step S3, a time T ₁₀₀ for holding the energization duty for the control valve 44 (heat generating element) at 100% which is the maximum value (hereinafter referred to as “maximum DUTY holding time”) is set. Setting the maximum DUTY hold time T ₁₀₀ is performed as follows based on the valve characteristics of the control valve 44.

FIG. 4 shows the valve characteristics (solid line) when the duty ratio for the control valve 44 (heating element) is changed from 0% to 100%, and the duty ratio for the control valve 44 (heating element) is changed from 100% to 0%. The valve characteristic (dashed line) is shown. The horizontal axis represents the holding time of the energization duty (operation amount output time), and the vertical axis represents the valve opening (lift amount).
For example, the target water temperature is changed from 110 ° C. to 80 ° C., and the valve opening of the control valve 44 is changed from “Vθa (◯)” corresponding to the target water temperature 110 ° C. to “Vθb (●)” corresponding to the target water temperature 80 ° C. Considering the case where it is necessary to increase, as shown in FIG. 4, when the duty ratio is 100%, that is, when the operation amount in the direction of increasing the valve opening is maximized, the valve opening of the control valve 44 is increased. The time required to change from “Vθa (◯)” to “Vθb (●)” is “T1”. Therefore, when the target water temperature is changed to 80 ° C. from 110 ° C., set this "T1" as the maximum DUTY retention time _{T 100.} Thus to set the maximum DUTY hold time T ₁₀₀ in response to changes in the target water temperature. This prevents the energization duty from being held at 100% longer than necessary, and suppresses an increase in power consumption.

In step S4, corrected in accordance with the engine load the maximum DUTY hold time _{T 100.} More specifically, to correct the larger the amount of change in the engine load or the engine load so as to increase the maximum DUTY hold time T _100. Increase of the maximum DUTY hold time T ₁₀₀ by the correction is determined in advance by experiment or the like. Here, if the engine load changes, the target water temperature also changes. Therefore, if the amount of change in the engine load increases, the deviation between the target water temperature and the actual water temperature naturally increases. Therefore, in step S4, it will be corrected as the higher the maximum DUTY hold time T ₁₀₀ is large deviation of the actual temperature and the target temperature is increased.
In the case where the operating state of the internal combustion engine 1 becomes the entire load range, in addition to the correction based on the engine load, to perform the further maximum DUTY hold time T ₁₀₀ largely to such correction (full load compensation) preferable.

In step S5, the correction in accordance with the maximum DUTY hold time _{T 100} a water pump (W / P) 2 of the discharge amount (rotational speed). Specifically, as the discharge amount of the water pump 2 is small (as the rotation speed is low) is corrected so as to increase the maximum DUTY hold time T _100. Increase of the maximum DUTY hold time T ₁₀₀ by the correction is determined in advance by experiment or the like.
In step S6, the energization duty for the control valve 44 (heat generating element) is maximized (100%). In other words, the operation amount for controlling the control valve 44 in the direction of increasing the valve opening is maximized.

On the other hand, if the target water temperature has changed from the low side to the high side in step S2, the process proceeds to step S7, and the time for holding the energization duty for the control valve 44 (heat generating element) at 0% which is the minimum value ( (Hereinafter referred to as “minimum DUTY holding time”) T ₀ is set. Setting the minimum DUTY hold time _{T 0,} like setting of the maximum DUTY hold time _{T 100,} on the basis of the valve characteristic of the control valves 44 (FIG. 4) performed as follows.
For example, the target water temperature is changed from 80 ° C. to 110 ° C., and the valve opening of the control valve 44 is changed from “Vθb (●)” corresponding to the target water temperature 80 ° C. to “Vθa (◯)” corresponding to the target water temperature 110 ° C. Considering the case where it is necessary to reduce the valve opening of the control valve 44 when the energization duty is 0%, that is, when the operation amount in the direction of decreasing the valve opening is maximized, as shown in FIG. The time required to change from “Vθb (●)” to “Vθa (◯)” is “T2”. Therefore, when the target water temperature changes from 80 ° C. to 110 ° C., this “T2” is set as the minimum DUTY holding time T ₀ . In this way, the minimum DUTY holding time T ₀ is set according to the change in the target water temperature.
Here, to set the maximum DUTY hold time _{T 100} and the minimum DUTY hold time _{T 0} and separately, as shown in FIG. 4, a valve opening speed of the control valve 44 when energization duty is 100%, This is because the valve closing speed of the control valve 44 when the energization duty is 0% is different, and in this embodiment, the minimum DUTY holding time T ₀ > the maximum DUTY holding time T ₁₀₀ is satisfied.

In step S8, corrected in accordance with the engine load the minimum DUTY retention time _{T 0.} More specifically, it corrected so as to increase the minimum DUTY retention time T ₀ the larger the amount of change as or engine load the engine load is small. The increment of the minimum DUTY holding time T ₀ due to this correction is determined in advance by experiments or the like.

In step S9, corrected in accordance with the discharge amount of the minimum DUTY hold time _{T 0} the water pump 2 (rpm). Specifically, correction is performed so that the minimum DUTY holding time T ₀ is increased as the discharge amount of the water pump 2 increases (the rotation speed increases). The increase in the minimum DUTY hold time T ₀ by the correction is determined in advance by experiment or the like.
In step S10, the energization duty for the control valve 44 (heat generating element) is set to the minimum (0%). In other words, the operation amount for controlling the control valve 44 in the direction of decreasing the valve opening is maximized.

In step S11, whether or not the holding time (the maximum DUTY holding time or the minimum DUTY holding time) has elapsed, or the deviation (absolute value) between the target water temperature and the actual water temperature is less than the threshold (for example, 5 ° C.). It is determined whether or not. Then, if the holding time has elapsed or the deviation (absolute value) between the target water temperature and the actual water temperature is less than the threshold value, the process proceeds to step S12 to shift from transient control to steady control. Otherwise, the process returns to step S1.
Note that the threshold value in step S1 and the threshold value in step S11 may be set to different values. In this case, it is preferable that the threshold value in step S1> the threshold value in step S11.

Here, the steady control executed in step S12 will be described separately for basic control and steady deviation absorption control.
(1) Basic control The control unit 5 has a control map in which the operation amount of the control valve 44, that is, the energization duty for the heating element is assigned for each target water temperature. Then, the basic operation amount (basic duty) of the control valve 44 is obtained by referring to the control map based on the set target water temperature. This basic operation amount is set in advance as a value corresponding to the valve opening degree of the control valve 44 that can control the temperature of the cooling water to be close to the target water temperature when the steady operation is performed under each operation condition. . The basic operation amount is basically such that the valve opening degree of the control valve 44 decreases (increases) as the target water temperature increases (lowers), that is, the flow rate (distribution) of the cooling water that passes through the radiator 3. Is set to be less (more).
Next, the control unit 5 corrects the basic operation amount according to the outside air temperature, and sets the operation amount of the control valve 44 (that is, the energization duty for the heating element). Specifically, the control unit 5 increases (decreases) the basic operation amount as the outside air temperature is higher (lower), that is, increases (reduces) the flow rate (distribution) of the cooling water passing through the radiator 3. ) And the operation amount of the control valve 44 is set.
At a constant time, the operation amount set in this way is output to the control valve 44.

(2) Steady deviation absorption control When the actual water temperature does not reach the target water temperature even though the control unit 5 outputs the operation amount set as described above to the control valve 44, the target water temperature and the actual water temperature The following processing is performed according to the deviation (absolute value) from the water temperature.
When the deviation (absolute value) between the target water temperature and the actual water temperature is equal to or greater than the above threshold value, the actual valve opening of the control valve 44 is set to the target due to the characteristic variation of the control valve 44 (individual variation, deterioration over time, etc.). It is considered that the original valve opening corresponding to the water temperature has not been reached. In such a case, the control unit 5 calculates the correction amount ΔDUTY necessary for making the actual valve opening of the control valve 44 the original valve opening corresponding to the target water temperature, and the calculated correction amount. ΔDUTY is added to the basic operation amount.
For example, when the target water temperature is 80 ° C. and the actual water temperature is 85 ° C., the actual valve opening degree Vθr is more than the original valve opening degree Vθt corresponding to the target water temperature, ΔT (here, 5T). 5), that is, the valve characteristic at the basic operation amount (here, the basic duty is 75%) when the target water temperature is 80 ° C., as shown in FIG. , The actual valve opening “Vθr (◯)” is considered to be the valve opening when the water temperature is 75 ° C. Therefore, in this case, based on the above valve characteristics, the actual valve opening “Vθr (◯)” is insufficient with respect to the original valve opening “Vθt (●)”. (Vθt−Vθr) is estimated, and the energization duty corresponding to the insufficient valve opening ΔVθ is calculated as the correction amount ΔDUTY and added to the basic operation amount. Thereby, the fluctuation of the valve opening due to the characteristic fluctuation of the control valve 44 is offset and the actual valve opening can be made the original valve opening, so that the actual water temperature is controlled to substantially the target water temperature.
On the other hand, when the deviation (absolute value) between the target water temperature and the actual water temperature is less than the threshold value, general PID control is performed to converge the actual water temperature to the target water temperature.
Note that the threshold value in the steady control may be set to a value different from the threshold value in step S1 or the threshold value in step S11.

  Returning to FIG. 3, when the change amount of the target water temperature is less than the threshold value in step S <b> 1, the process proceeds to step S <b> 13 to determine whether or not the transient control is being executed. If the transient control is being executed, the process proceeds to step S14. If the transient control is not being executed, the process proceeds to step S12 to execute the steady control.

  In step S14, it is determined whether knocking has occurred. This determination is made based on the detection signal of the knock sensor 63. If knocking has occurred, the process proceeds to step S15. If knocking has not occurred, the process proceeds to step S11.

In step S15, it corrects the maximum DUTY retention time _{T 100} in accordance with the knocking level. More specifically, it corrected so as knocking level is increased higher of the maximum DUTY hold time T ₁₀₀ time. Then, the process proceeds to step S11 after correcting the maximum DUTY hold time _{T 100.}

FIG. 6 is a timing chart of the transient control for the control valve 44.
As shown in FIG. 6, when the target water temperature changes from the low side to the high side, the control unit 5 sets the energization duty for the control valve 44 (heat generating element) to the minimum (0%) (time t1). As a result, the valve closing speed of the control valve 44 is increased, and the flow rate (distribution) of the cooling water passing through the radiator 3 is rapidly reduced to increase the temperature of the cooling water. Thereafter, when the minimum DUTY holding time T ₀ has elapsed or the deviation between the target water temperature and the actual water temperature is less than the above threshold value, the transient control is terminated and the routine shifts to the steady control (here, the energization duty is 25%). (Time t2).

On the other hand, when the target water temperature changes from the higher side to the lower side, the control unit 5 maximizes the energization duty of the control valve 44 (heat generating element) (100%) (time t3). Thereby, the valve opening speed of the control valve 44 is increased, and the temperature of the cooling water is lowered by rapidly increasing the flow rate (distribution) of the cooling water that passes through the radiator 3. Thereafter, the maximum DUTY retention time T ₁₀₀ elapses or deviation stationary control terminates the transient time control becomes smaller than the threshold value and the actual water temperature and the target temperature (here, the energization duty is 75%) moves to (Time t4).

The control unit 5 executes such transient control, thereby suppressing the operation delay of the control valve 44 as much as possible to enhance the responsiveness of the cooling water temperature control. Here, the time for minimizing the operation amount of the control valve 44 is limited within the minimum DUTY holding time T ₀ , and the time for maximizing the operation amount of the control valve 44 is limited within the maximum DUTY holding time T _100. Therefore, overshoot is also suppressed.

Next, the control of the water pump 2 executed by the control unit 5 is executed mainly after the warm-up control of the internal combustion engine 1 that is executed immediately after starting, and after the warm-up of the internal combustion engine 1 is completed by this warm-up control. This will be described separately in the post-warm-up control.
(1) Warm-up control From the start of the internal combustion engine 1 to the completion of warm-up, the control unit 5 promotes warm-up of the internal combustion engine 1 by operating the water pump 2 intermittently. In this warm-up control, the control valve 44 is closed.
For example, when the actual water temperature is lower than the first determination temperature (for example, target water temperature −20 ° C.), the control unit 5 does not operate the water pump 2 until the actual water temperature reaches the first determination temperature. Thereafter, when the actual water temperature reaches the first determination temperature, the control unit 5 operates the water pump 2 to check the actual water temperature after a predetermined time has elapsed, and when the actual water temperature is lower than the target water temperature. The operation of the water pump 2 is stopped. After that, when the actual water temperature reaches the second determination temperature (for example, target water temperature −10 ° C.), the control unit 5 operates the water pump 2 and confirms the actual water temperature after a predetermined time has elapsed. If the actual water temperature is lower than the target water temperature, the operation of the water pump 2 is stopped again. In this way, the control unit 5 repeats the operation and stop of the water pump 2, intermittently operates the water pump 2 to promote warm-up, and the actual water temperature becomes the warm-up completion temperature (for example, target temperature − When the temperature reaches 5 ° C., the warm-up control is terminated (the warm-up is completed).

(2) After Warm-Up Completion FIG. 7 is a flowchart showing the control for the water pump executed by the control unit 5 after the warm-up is completed.
In FIG. 7, in step S21, as in step S1 of FIG. If the amount of change in the target water temperature is equal to or greater than the threshold value, the process proceeds to step S22 to execute the transient control.
In step S22, as in step S2 of FIG. 3, it is determined whether or not the target water temperature has changed from a high side to a low side. If the target water temperature has changed from a high side to a low side, the process proceeds to step S23. .

In step S23, the discharge amount (rotation speed) of the water pump 2 is increased. Specifically, the energization duty for the water pump 2 is increased by a predetermined amount.
In step S24, the discharge amount of the water pump 2 is corrected according to the engine load. Specifically, the discharge amount of the water pump 2 is increased as the engine load or the change amount of the engine load is larger. The increase in the discharge amount due to this correction is determined in advance by experiments or the like. Here, if the engine load changes, the target water temperature also changes. Therefore, if the amount of change in the engine load increases, the deviation between the target water temperature and the actual water temperature naturally increases. Therefore, in this step S23, the discharge amount of the water pump 2 is corrected to increase as the deviation between the target water temperature and the actual water temperature increases.
When the operating state of the internal combustion engine 1 is in the full load region, it is preferable to add a correction (full load correction) for further increasing the discharge amount in addition to the correction based on the engine load.

On the other hand, when the target water temperature has changed from the low side to the high side in step S22, the process proceeds to step S25, and the discharge amount (rotation speed) of the water pump 2 is decreased. Specifically, the energization duty for the water pump 2 is decreased by a predetermined amount.
In step S26, the discharge amount of the water pump 2 is corrected according to the engine load. Specifically, the discharge amount of the water pump 2 is decreased as the engine load is smaller or the change amount of the engine load is larger. Note that a decrease in the discharge amount due to this correction is determined in advance by experiments or the like.

  In step S27, as in step S11 of FIG. 3, whether or not the holding time (the maximum DUTY holding time or the minimum DUTY holding time) has elapsed, or the deviation (absolute value) between the target water temperature and the actual water temperature is determined. It is determined whether or not the value is less than the threshold value. Then, if the holding time has elapsed or the deviation (absolute value) between the target water temperature and the actual water temperature is less than the threshold value, the process proceeds to step S28, and transition from transient control to steady control is performed. Otherwise, the process returns to step S21.

Here, the steady control executed in step S28 will be described.
The control unit 5 has a control map (not shown) in which the operation amount of the water pump 2, that is, the energization duty for the water pump 2 is assigned for each target water temperature, and the target set based on the engine operating state. The operation amount of the water pump 2 is obtained by referring to the control map based on the water temperature, and the obtained operation amount is output to the water pump 2.

  Returning to FIG. 7, when the amount of change in the target water temperature is less than the threshold value in step S21, the process proceeds to step S29, and it is determined whether or not the transient control is being executed, as in step S13 of FIG. . If the transient control is being executed, the process proceeds to step S30. If the transient control is not being executed, the process proceeds to step S28 to execute the steady control.

In step S30, as in step S14 of FIG. 3, it is determined whether knocking has occurred. If knocking has occurred, the process proceeds to step S31. If knocking has not occurred, the process proceeds to step S28.
In step S31, the discharge amount to the water pump 2 is maximized. Then, after the discharge amount of the water pump 2 is maximized, the process proceeds to step S27.
If knocking continues to occur even when the deviation between the target water temperature and the actual water temperature is equal to or lower than the above threshold, the discharge amount of the water pump 2 is maintained at the maximum.

FIG. 8 is a timing chart of the transient control for the water pump 2.
As shown in FIG. 8A, when the target water temperature changes from the low side to the high side, the control unit 5 sets the operation amount (energization duty) of the water pump 2 corresponding to the target water temperature (after change) to a predetermined amount. The discharge amount is decreased by reducing the discharge amount (time t1). As described above, at this time, the control unit 5 minimizes the energization duty for the control valve 44 (heat generating element) (0%), that is, the operation amount for controlling the control valve 44 in the direction of decreasing the valve opening degree. Is the maximum. As a result, the flow rate of the cooling water passing through the radiator 3 can be further reduced, and the rising speed of the cooling water temperature can be increased. Then, when the deviation between the target water temperature and the actual water temperature is less than the threshold value, the transient control is terminated and the routine shifts to the steady control (time t2).

  On the other hand, as shown in FIG. 8B, when the target water temperature changes from the high side to the low side, the control unit 5 sets the operation amount (energization duty) of the water pump 2 corresponding to the target water temperature (after the change). The discharge amount is increased by increasing the predetermined amount (time t3). As described above, at this time, the control unit 5 minimizes the energization duty for the control valve 44 (heat generating element) (0%), that is, the operation amount for controlling the control valve 44 in the direction of increasing the valve opening. Is the maximum. As a result, the flow rate of the cooling water passing through the radiator 3 can be further increased, and the cooling rate of the cooling water can be increased. Then, when the deviation between the target water temperature and the actual water temperature is less than the threshold value, the transient control is terminated and the routine shifts to the steady control (time t4).

Thus, in the present embodiment, when the target temperature changes, the control unit 5 executes the transient control for the water pump 2 together with the transient control for the control valve 44. As a result, the operation delay of the control valve 44 can be compensated by increasing or decreasing the flow rate of the cooling water, and the responsiveness of the temperature control of the cooling water is further improved. Here, the time of increasing the discharge amount of the water pump 2, since it is restricted within the maximum DUTY hold time T _100, it is possible to suppress an increase in power consumption due to the time of the transient control to a minimum.

  According to the embodiment described above, when the target water temperature is changed and the temperature of the cooling water is increased, the flow rate of the cooling water (by controlling the water pump 2 to reduce the discharge amount and bypassing the radiator 3 ( The control valve 44 is controlled so as to increase the distribution), and when the target water temperature changes and the cooling water temperature needs to be lowered, the water pump 2 is controlled to increase the discharge amount and the radiator 3 is increased. The control valve 44 is controlled so as to increase the flow rate (distribution) of the cooling water that passes through. That is, at the time of transition when the target water temperature has changed, the adjustment of the circulating flow rate of the cooling water by the water pump 2 and the adjustment of the flow rate of the cooling water that does or does not pass the radiator 3 by the control valve 44 are simultaneously performed. As a result, since the operation delay of the control valve 44 can be effectively compensated, the responsiveness of the temperature control of the cooling water can be greatly improved as compared with the conventional case.

Here, when the deviation between the target water temperature and the actual water temperature is equal to or greater than the above threshold value, the transient control for the control valve 44 and the transient control for the water pump 2 are performed, so that the power consumption is significantly increased. It is suppressed.
Further, since the operation amount of the control valve 44 and the operation amount of the water pump 2 are increased / decreased according to the deviation between the target water temperature and the actual water temperature, the response to the temperature control of the reject water while suppressing a significant increase in power consumption. The property can be further improved.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, A deformation | transformation and change are possible based on the technical idea of this invention.
Here, technical ideas other than the claims that can be grasped from the embodiment and the modifications thereof will be described together with the effects thereof.

(A) A cooling control device for an internal combustion engine according to any one of claims 1 to 3,
The controller, when increasing the temperature of the cooling water, outputs a maximum value of an operation amount for controlling the control valve in a direction to increase a flow rate of the cooling water that bypasses the radiator for a first predetermined time, When lowering the temperature of the cooling water, the maximum value of the operation amount for controlling the control valve in the direction of increasing the flow rate of the cooling water passing through the radiator is output for a second predetermined time.
(B) The internal combustion engine cooling control apparatus according to any one of (a) above,
The controller sets the first predetermined time and the second predetermined time according to a deviation between a target temperature of the cooling water and an actual temperature of the cooling water.
According to the above (a) and (b), the operation delay of the control valve can be reduced while suppressing overshoot. Thereby, the responsiveness to the temperature control of the cooling water can be enhanced.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Water pump (W / P), 3 ... Radiator, 4 ... Circulation path, 5 ... Control part, 43 ... Bypass flow path, 44 ... Control valve, 61 ... Water temperature sensor

Claims (3)

A cooling control device for an internal combustion engine that controls the temperature of cooling water according to an engine operating state,
A water pump with variable discharge rate,
A cooling water circulation path for circulating the cooling water discharged from the water pump between the internal combustion engine and the radiator;
A bypass flow path for bypassing the radiator;
A control valve capable of changing a flow rate distribution of the cooling water that passes through the radiator and the cooling water that bypasses the radiator;
A control unit for controlling the water pump and the control valve,
The controller is
When the temperature of the cooling water is increased, the water pump is controlled to decrease the discharge amount, and the control valve is controlled to increase the flow rate of cooling water that bypasses the radiator,
An internal combustion engine that controls the water pump so as to increase the discharge amount and controls the control valve so as to increase the flow rate of the cooling water passing through the radiator when the temperature of the cooling water is decreased Cooling control device.   The control unit executes the control relating to the water pump and the control relating to the control valve when a deviation between a target temperature of the cooling water and an actual temperature of the cooling water is equal to or greater than a preset threshold value. The cooling control apparatus for an internal combustion engine according to claim 1.   The cooling control for an internal combustion engine according to claim 1 or 2, wherein the control unit increases or decreases an operation amount of the water pump according to a deviation between a target temperature of the cooling water and an actual temperature of the cooling water. apparatus.

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