JP5152595B2 - Control device for vehicle cooling system - Google Patents

Description

  The present invention relates to a control device for a cooling system for a vehicle, which includes an electronic thermostat having a valve for switching a cooling water circulation path of an internal combustion engine and a heater for adjusting a cooling water temperature region where the valve opens. It is an invention.

  Generally, a cooling system for an internal combustion engine mounted on a vehicle is, for example, a cooling water circulation circuit that circulates cooling water between an internal combustion engine and a radiator as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2001-329840). When a thermostat is installed on the way and the cooling water temperature is lower than a predetermined temperature (for example, the temperature corresponding to the completion of warming-up), the thermostat valve is closed to prevent the cooling water from circulating to the radiator (bypassing the cooling water) The temperature of the cooling water on the internal combustion engine side is rapidly increased to promote warming up of the internal combustion engine, and then the thermostat is turned on when the cooling water temperature exceeds a predetermined temperature. The valve is opened and switched to a flow path that circulates the coolant through the radiator. So as to prevent overheating of the internal combustion engine is adjusted to the range.

  As a thermostat mounted in such a cooling system, for example, there is one that adopts a wax pellet type thermostat that opens and closes a valve by using expansion / contraction due to temperature change of the thermowax enclosed in the pellet. Some electronic thermostats have built-in heaters that heat the thermowax, and that can control the energizing power of the heaters to adjust the cooling water temperature region in which the valve opens.

JP 2001-329840 A

  The inventor sets a target cooling water temperature according to the operating state (for example, rotation speed and load) of the internal combustion engine in a cooling system equipped with an electronic thermostat, and also opens the valve opening characteristics of the electronic thermostat [for example, as shown in FIG. Considering the relationship between the energization power of the heater, the cooling water temperature, and the valve lift (valve opening)], the heater according to the operating state of the internal combustion engine is set so that the valve of the electronic thermostat opens near the target cooling water temperature. We are researching a system for setting the energization power of the following, but the following new problems were found in the research process.

  As shown in FIG. 5, when the valve opening characteristics change due to changes in the electronic thermostat over time (for example, changes in the characteristics of the thermowax or the springs that energize the valve), the energization power of the heater and the valve opening water temperature region (The cooling water temperature region where the valve opens) changes, and the relationship between the heater energizing power and the valve lift amount changes, so even if the heater energizing power is the same, the valve lift amount changes. The cooling water temperature cannot be accurately controlled to the target cooling water temperature.

  For example, if the valve opening water temperature region changes to the high temperature side with respect to the heater energization power, the valve lift amount decreases even if the heater energization power is the same, so the flow rate of cooling water circulating to the radiator decreases, The cooling water temperature becomes higher than the target cooling water temperature. As a result, the knock region of the internal combustion engine is expanded and the ignition timing retardation amount by the knock control is increased, so that the torque may be reduced and fuel consumption may be deteriorated, and overheating may be caused.

  On the other hand, when the valve opening water temperature region changes to the low temperature side with respect to the heater energization power, the valve lift amount increases even if the heater energization power is the same, so the flow rate of cooling water circulating to the radiator increases, The cooling water temperature is lower than the target cooling water temperature. As a result, the friction of the internal combustion engine may increase and fuel consumption may deteriorate.

  Therefore, the problem to be solved by the present invention is to provide a control device for a vehicle cooling system that can accurately control the cooling water temperature to the target cooling water temperature even if the valve opening characteristic of the electronic thermostat changes. It is in.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a valve for switching between a flow path for circulating cooling water of an internal combustion engine to a radiator and a flow path for not circulating to the radiator, and cooling for opening the valve. In a control device for a vehicle cooling system having an electronic thermostat having a heater for adjusting a water temperature region, a cooling water temperature sensor for detecting a cooling water temperature, and an energization power of the electronic thermostat heater according to an operating state of the internal combustion engine The heater control means for controlling the cooling water temperature to the target cooling water temperature by adjusting the cooling water temperature region where the valve of the electronic thermostat opens, and whether or not the valve opening characteristic of the electronic thermostat has changed. and a valve opening characteristic change determination means for determining, the heater control means, a heater which is set in accordance with the operating state of the internal combustion engine Have a correcting means for correcting, based on the deviation between the coolant temperature and the target cooling water temperature detected an DENDEN force in the cooling water temperature sensor, the correction means, the valve opening characteristics are changed by the valve opening characteristic change determination means When it is determined that the heater is energized, the energization power of the heater is corrected .

In this configuration, there is a deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to changes in the valve opening characteristics of the electronic thermostat (the relationship between the heater energization power, cooling water temperature, and valve lift). In addition, by correcting the energization power of the heater based on the deviation between the cooling water temperature detected by the cooling water temperature sensor and the target cooling water temperature, the deviation between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics of the electronic thermostat ( The energization power of the heater can be corrected so as to reduce the cooling water temperature deviation). Thereby, even if the valve opening characteristic of the electronic thermostat changes, the cooling water temperature can be accurately controlled to the target cooling water temperature, and fuel consumption deterioration and overheating due to a decrease in the cooling water temperature control accuracy can be prevented.
In addition, a valve opening characteristic change determining means for determining whether or not the valve opening characteristic of the electronic thermostat has changed is provided, and when it is determined by the valve opening characteristic change determining means that the valve opening characteristic has changed. Since the heater energization power is corrected, when the valve opening characteristic change determining means determines that the valve opening characteristic has changed, the cooling water temperature and the target cooling are changed by the change in the valve opening characteristic of the electronic thermostat. Judging that the deviation (cooling water temperature deviation) from the water temperature has increased, the heater energizing power is set to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics. It can be corrected.

In this case, may be corrected energization power of the heater in accordance with the steady deviation between the coolant temperature and the target cooling water temperature detected by the coolant temperature sensor, but as of claim 2, detected by the coolant temperature sensor The energization power of the heater may be feedback-corrected so that the cooling water temperature thus made coincides with the target cooling water temperature. In this way, the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in the valve opening characteristics of the electronic thermostat can be quickly and accurately reduced.

  By the way, when the valve opening characteristics of the electronic thermostat change, the relationship between the heater energizing power and the valve opening water temperature region (the cooling water temperature region where the valve opens) changes, and the heater energizing power and the valve lift amount Therefore, even if the heater energization power is the same, the lift amount of the valve changes (the deviation between the actual lift amount and the target lift amount increases). When the lift amount of the valve changes, the flow rate of the cooling water circulating to the radiator changes accordingly, and the cooling water temperature changes. In addition, when the lift amount of the valve changes, the pressure loss of the entire cooling water circulation passage changes accordingly, the flow rate of the cooling water on the discharge side of the water pump changes, and the pressure difference between the front and rear of the water pump (water The pressure difference between the cooling water pressure on the discharge port side of the pump and the cooling water pressure on the suction port side of the water pump changes.

  Therefore, when the lift amount of the valve changes due to a change in the valve opening characteristics of the electronic thermostat, the flow rate of the cooling water circulating to the radiator or between the cooling water flow rate on the discharge side of the water pump and the cooling water temperature There is also a correlation, and there is a correlation between the pressure difference before and after the water pump and the cooling water temperature.

Therefore, focusing on the fact that there is a correlation between the flow rate of the cooling water circulating to the radiator and the flow rate of the cooling water at the discharge port side of the water pump and the cooling water temperature, the cooling flowing through the radiator as in claim 3. A flow rate sensor that detects the flow rate of water or the flow rate of cooling water on the outlet side of the water pump that circulates the cooling water is provided, and the flow rate detected by the flow rate sensor is determined by the flow rate sensor. You may make it correct | amend based on the deviation with a target flow volume. In this way, the energization power of the heater is corrected so that the deviation between the flow rate detected by the flow sensor (the flow rate of cooling water flowing through the radiator or the flow rate of cooling water on the outlet side of the water pump) and the target flow rate is reduced. By doing so, the energization power of the heater can be corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in the valve opening characteristics of the electronic thermostat.

Alternatively, focusing on that there is a correlation between the pressure difference across the water pump and the cooling water temperature, as claimed in claim 4, the pressure of the cooling water discharge port side of the water pump for circulating cooling water Pressure difference detecting means for detecting a pressure difference from the cooling water pressure on the suction side of the water pump (for example, a discharge side pressure sensor for detecting the pressure of the cooling water on the discharge port side of the water pump and a suction port of the water pump) The suction side pressure sensor for detecting the pressure of the cooling water on the side of the heater is provided, and the energization power of the heater set according to the operating state of the internal combustion engine is set to the deviation between the pressure difference detected by the pressure difference detecting means and the target pressure difference. You may make it correct | amend based. In this way, the electric thermostat power is corrected so as to reduce the deviation between the pressure difference detected by the pressure difference detection means (pressure difference before and after the water pump) and the target pressure difference, thereby opening the valve of the electronic thermostat. The energization power of the heater can be corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in the valve characteristics.

Further, as in claims 3 and 4 , there is provided valve opening characteristic change determining means for determining whether or not the valve opening characteristic of the electronic thermostat has changed, and the valve opening characteristic change determining means provides the valve opening characteristic. When it is determined that has changed, the energization power of the heater may be corrected. In this way, when the valve opening characteristic change determining means determines that the valve opening characteristic has changed, the deviation (cooling) between the cooling water temperature and the target cooling water temperature due to the change in the valve opening characteristic of the electronic thermostat. It is determined that the water temperature deviation) has increased, and the energization power of the heater can be corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics.

In this case, as in claim 5 , (1) the cooling water temperature sensor for detecting the cooling water temperature, (2) the flow rate of the cooling water flowing through the radiator or the flow rate of the cooling water on the outlet side of the water pump that circulates the cooling water. A flow sensor for detecting, (3) at least one of pressure difference detecting means for detecting a pressure difference between the pressure of the cooling water on the discharge side of the water pump and the pressure of the cooling water on the suction side of the water pump. Provided, and the valve opening characteristic change determining means determines whether or not the valve opening characteristic has changed based on a deviation between a detected value of any one of the coolant temperature sensor, the flow rate sensor, and the pressure difference detecting means and the target value. It is good to do so.

  (1) When the valve lift amount changes due to a change in the valve opening characteristics of the electronic thermostat, the flow rate of the cooling water circulating to the radiator changes accordingly, and the cooling water temperature changes. Therefore, if the deviation between the coolant temperature detected by the coolant temperature sensor and the target coolant temperature is monitored, it can be determined whether or not the valve opening characteristic has changed.

  (2) When the valve lift amount changes due to a change in the valve opening characteristics of the electronic thermostat, the flow rate of the cooling water circulating to the radiator changes accordingly. Further, when the lift amount of the valve changes, the pressure loss of the entire cooling water circulation channel changes accordingly, and the flow rate of the cooling water on the outlet side of the water pump changes. Therefore, if the deviation between the flow rate detected by the flow rate sensor (the flow rate of cooling water flowing to the radiator or the flow rate of cooling water on the outlet side of the water pump) and the target flow rate is monitored, whether or not the valve opening characteristics have changed. Can be determined.

  (3) When the lift amount of the valve changes due to the change in the valve opening characteristics of the electronic thermostat, the pressure loss of the entire cooling water circulation channel changes accordingly, and the pressure difference between the water pump and the front and rear of the water pump (water pump discharge port) The pressure difference between the pressure of the cooling water on the side and the pressure of the cooling water on the inlet side of the water pump changes. Therefore, by monitoring the deviation between the pressure difference detected by the pressure difference detecting means and the target pressure difference, it can be determined whether or not the valve opening characteristic has changed.

  Generally, before the warm-up of the internal combustion engine is completed (during warm-up control), the valve of the electronic thermostat is maintained in the closed state. It hardly appears in parameters (for example, cooling water temperature, cooling water flow rate, cooling water pressure difference, etc.) for determining changes in valve characteristics. Further, during transient operation in which the operation state (for example, rotation speed or load) of the internal combustion engine changes, the target cooling water temperature, the flow rate of the cooling water, and the like are not stable, so the parameters for determining the change in the valve opening characteristics are not stable. Therefore, it is difficult to accurately determine whether or not the valve opening characteristics have changed before the completion of warm-up of the internal combustion engine or during transient operation.

Such circumstances in mind, as in claim 6, it is preferable to be determined whether the valve opening characteristics are changed during steady operation after warm-up of the internal combustion engine. In this way, the influence of the change in the valve opening characteristic of the electronic thermostat is likely to appear in parameters for determining the change in the valve opening characteristic (for example, cooling water temperature, cooling water flow rate, cooling water pressure difference, etc.) Further, when the parameter for determining the change in the valve opening characteristic is stabilized, it can be determined whether or not the valve opening characteristic has changed, and the change in the valve opening characteristic can be detected with high accuracy.

FIG. 1 is a diagram showing a schematic configuration of an engine cooling system in Embodiment 1 of the present invention. FIG. 2 is a diagram conceptually illustrating an example of a target cooling water temperature map. FIG. 3 is a diagram conceptually illustrating an example of a heater energization power map. FIG. 4 is a diagram for explaining the valve opening characteristics of the electronic thermostat. FIG. 5 is a diagram for explaining the change over time in the valve opening characteristics of the electronic thermostat. FIG. 6 is a time chart for explaining the relationship between the valve lift amount of the electronic thermostat and the cooling water temperature. FIG. 7 is a time chart for explaining a method for correcting the heater energization power. FIG. 8 is a flowchart for explaining the flow of processing of the heater control routine. FIG. 9 is a flowchart for explaining the flow of processing of the heater energization power correction routine. FIG. 10 is a time chart for explaining the relationship between the valve lift amount of the electronic thermostat and the flow rate of the cooling water on the discharge port side of the water pump in the second embodiment. FIG. 11 is a time chart for explaining the relationship between the valve lift amount of the electronic thermostat and the pressure difference before and after the water pump in the third embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine cooling system will be described with reference to FIG.
A water pump (hereinafter referred to as “W / P”) 12 is provided in the vicinity of the inlet of the cooling water passage (water jacket) of the engine 11 that is an internal combustion engine. The W / P 12 is an electric W / P driven by a motor or a mechanical W / P driven by the power of the engine 11. The outlet of the cooling water passage of the engine 11 and the inlet of the radiator 13 are connected by a cooling water circulation pipe 14, and the outlet of the radiator 13 and the inlet of the W / P 12 are connected by a cooling water circulation pipe 15. As a result, a cooling water circulation circuit 16 is constructed in which the cooling water circulates in the path of the cooling water passage of the engine 11 → the cooling water circulation pipe 14 → the radiator 13 → the cooling water circulation pipe 15 → W / P 12 → the cooling water passage of the engine 11. .

  The cooling water circulation circuit 16 is provided with a bypass flow path 17 in parallel with the radiator 13, and both ends of the bypass flow path 17 are connected to the cooling water circulation pipes 14 and 15. An electronic thermostat 18 that opens and closes according to the cooling water temperature is provided in the vicinity of the connection portion between the bypass flow path 17 and the cooling water circulation pipe 15, and the cooling water temperature is lower than a predetermined temperature (for example, a temperature corresponding to completion of warming up). Sometimes, the valve 18a of the electronic thermostat 18 is closed and switched to a flow path for circulating the coolant from the engine 11 through the bypass flow path 17 so that the coolant temperature inside the engine 11 can be quickly raised to increase the engine temperature. Promote 11 warm-up. Thereafter, when the cooling water temperature becomes equal to or higher than a predetermined temperature, the valve 18a of the electronic thermostat 18 is opened, and the cooling water from the engine 11 is switched to a flow path for circulating the cooling water to the radiator 13, whereby the radiator 13 The engine 11 is prevented from overheating by adjusting the cooling water temperature within an appropriate warm-up temperature range by the heat radiation action.

  The electronic thermostat 18 is a wax pellet type thermostat that opens and closes the valve 18a by utilizing expansion / contraction due to temperature change of the thermo wax enclosed in the pellet, and has a built-in heater 18b for heating the thermo wax. The valve opening water temperature region (the cooling water temperature region where the valve 18a opens) can be adjusted in accordance with the energized power (see FIG. 4).

  An electric cooling fan 19 that generates cooling air is disposed in the vicinity of the radiator 13. A cooling water temperature sensor 21 for detecting the cooling water temperature at or near the outlet of the cooling water passage is disposed at or near the outlet of the cooling water passage of the engine 11. A cooling water temperature sensor that detects the cooling water temperature at or near the inlet of the cooling water passage may be disposed at or near the inlet of the cooling water passage of the engine 11.

  Further, a heating hot water circuit 22 is connected to the cooling water circulation circuit 16 in parallel to the engine 11. A heater core 23 for heating is provided in the middle of the hot water circuit 22, and a heater blower 24 that generates hot air is disposed in the vicinity of the heater core 23.

  The cylinder block of the engine 11 is provided with a crank angle sensor 25 that outputs a pulse signal every time the crankshaft rotates a predetermined crank angle. Based on the output signal of the crank angle sensor 25, the crank angle and the engine rotational speed are attached. Is detected. Further, the intake air amount sensor 26 such as an air flow meter detects the intake air amount, and the vehicle speed sensor 27 detects the vehicle speed.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 28. The ECU 28 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby control a fuel injection valve (not shown) according to the engine operating state. The fuel injection amount and the ignition timing of a spark plug (not shown) are controlled.

  Further, the ECU 28 executes various cooling water temperature control routines (not shown) and refers to the target cooling water temperature map shown in FIG. 2 to determine the engine operating state [for example, the engine speed and engine load (intake air amount). , Intake pipe negative pressure, throttle opening, etc.)], and the W / P 12, the electronic thermostat 18 and the electric cooling fan 19 are controlled so as to realize the target cooling water temperature. When the W / P 12 is a mechanical W / P, the electronic thermostat 18 and the electric cooling fan 19 are controlled so as to achieve the target cooling water temperature. The target cooling water temperature map of FIG. 2 is created in advance so as to optimize fuel consumption and emission based on experimental data, design data, and the like, and is stored in the ROM of the ECU 28.

  When the electronic thermostat 18 is controlled, the ECU 28 executes a heater control routine shown in FIG. 8 to be described later, thereby referring to a map of heater energization power (energization power of the heater 18b) shown in FIG. The heater energization power corresponding to [for example, engine speed and engine load (intake air amount, intake pipe negative pressure, throttle opening, etc.)] is calculated. The heater energizing power map of FIG. 3 is based on the valve opening characteristics of the electronic thermostat 18 [for example, heater energizing power, cooling water temperature, lift amount of the valve 18a shown in FIG. In relation to the amount), the valve 18a of the electronic thermostat 18 is opened near the target cooling water temperature and stored in the ROM of the ECU 28.

  However, as shown in FIG. 5, when the valve opening characteristic changes due to a change with time of the electronic thermostat 18 (for example, a characteristic change of the thermo wax or a characteristic change of a spring for energizing the valve 18a), the heater energization power and the valve opening power are changed. Since the relationship between the valve water temperature region (the cooling water temperature region where the valve 18a opens) changes and the relationship between the heater energization power and the lift amount of the valve 18a changes, the lift amount of the valve 18a even if the heater energization power is the same. Changes, and the cooling water temperature cannot be accurately controlled to the target cooling water temperature.

  For example, when the valve opening water temperature region changes to the high temperature side with respect to the heater energizing power, the lift amount of the valve 18a becomes small even if the heater energizing power is the same, so the flow rate of the cooling water circulating to the radiator 13 decreases, The cooling water temperature becomes higher than the target cooling water temperature. As a result, the knock region of the engine 11 is expanded and the ignition timing retardation amount by the knock control is increased, so that there is a possibility that the torque is reduced and fuel consumption is deteriorated, and overheating may be caused.

  On the other hand, when the valve opening water temperature region changes to the low temperature side with respect to the heater energizing power, the lift amount of the valve 18a increases even if the heater energizing power is the same, so the flow rate of the cooling water circulating to the radiator 13 increases. The cooling water temperature is lower than the target cooling water temperature. As a result, there is a possibility that the friction of the engine 11 will increase and the fuel efficiency will deteriorate.

  As a countermeasure against this, the ECU 28 executes a heater energization power correction routine shown in FIG. 9 to be described later, thereby obtaining a deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to a change in the valve opening characteristic of the electronic thermostat 18. The heater energization power is corrected as follows so as to be reduced.

  First, depending on whether or not the absolute value of the deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 and the target cooling water temperature during the steady operation after the engine 11 is warmed up is equal to or greater than a predetermined determination value, the electronic thermostat 18 It is determined whether or not the valve opening characteristic has changed.

  As shown in FIG. 6, when the lift amount of the valve 18a changes due to a change in the valve opening characteristic of the electronic thermostat 18 (the deviation between the actual lift amount and the target lift amount increases), the radiator 13 is accordingly changed. The flow rate of the circulating cooling water changes, and the cooling water temperature changes. Therefore, if the deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 and the target cooling water temperature is monitored, it can be accurately determined whether or not the valve opening characteristic has changed.

  Then, as shown in FIG. 7, it is determined that the valve opening characteristic has changed because the absolute value of the deviation between the actual cooling water temperature and the target cooling water temperature becomes equal to or greater than the determination value due to the change in the valve opening characteristic of the electronic thermostat 18. At the time point t1, the heater energization power is feedback-controlled (hereinafter referred to as “F / B”) so that the actual cooling water temperature detected by the cooling water temperature sensor 21 matches the target cooling water temperature. Thus, the heater energization power is F / B corrected so as to reduce the deviation between the actual cooling water temperature and the target cooling water temperature (the deviation of the cooling water temperature) due to the change in the valve opening characteristics.

  Thereafter, at the time t2 when it is determined by the F / B control that the actual cooling water temperature substantially coincides with the target cooling water temperature, the F / B correction amount of the heater energization power is learned as the learning correction amount of the heater energization power, and the learning is performed. The data is stored in a rewritable nonvolatile memory (a rewritable memory that retains stored data even when the ECU 28 is powered off) such as a backup RAM (not shown) of the ECU 28. In this case, a common learning correction amount may be learned in all operating regions, or a learning correction amount for each learning region divided according to the engine operating state (for example, engine speed and engine load). You may learn.

  The ECU 28 corrects the heater energization power calculated according to the engine operating state by using this learning correction amount, so that the deviation between the cooling water temperature and the target cooling water temperature due to the change in the valve opening characteristic (deviation of the cooling water temperature). The heater energization power is corrected so as to reduce the current.

  The processing contents of the heater control routine of FIG. 8 and the heater energization power correction routine of FIG. 9 executed by the ECU 28 will be described below. These routines shown in FIGS. 8 and 9 serve as heater control means in the claims.

[Heater control routine]
The heater control routine shown in FIG. 8 is repeatedly executed at a predetermined cycle while the ECU 28 is powered on. When this routine is started, first, in step 101, referring to the heater energizing power map shown in FIG. 3, the engine operating state [for example, engine speed and engine load (intake air amount, intake pipe negative pressure, throttle Heater energization power corresponding to the opening degree etc.] is calculated.

  Thereafter, the process proceeds to step 102, and the F / B correction amount and the learning correction amount of the heater energization power are read. Here, the F / B correction amount is calculated during the execution of the F / B control of the heater energization power in the routine of FIG. 9 described later (F / B correction amount = 0 when the F / B control is stopped). . Further, the learning correction amount is learned by the routine shown in FIG. 9 described later, and the learning correction amount common to all the operation regions stored in the nonvolatile memory such as the backup RAM of the ECU 28 is read. Alternatively, the learning correction amount in the learning region corresponding to the current engine operating state is read from the learning data stored in the nonvolatile memory such as the backup RAM of the ECU 28.

Thereafter, the process proceeds to step 103, and the final heater energizing power is obtained by adding the F / B correction amount and the learning correction amount to the heater energizing power.
Final heater energizing power = heater energizing power + F / B correction amount + learning correction amount Thereafter, the routine proceeds to step 104 where the energization of the heater 18b of the electronic thermostat 18 is controlled so as to realize the final heater energizing power.

[Heater conduction power correction routine]
The heater energization power correction routine shown in FIG. 9 is repeatedly executed at a predetermined cycle while the ECU 28 is turned on, and serves as correction means in the claims. When this routine is started, first, at step 201, it is determined whether or not the engine 11 has been warmed up by, for example, whether or not the coolant temperature is equal to or higher than a predetermined temperature. If it is determined in step 201 that it is not after the engine 11 has been warmed up (before the warm-up has been completed), the process proceeds to step 209 to continue the warm-up control.

  Thereafter, when it is determined in step 201 that the engine 11 has been warmed up, the routine proceeds to step 202, where whether or not the engine 11 is in steady operation is determined based on the engine operating state (for example, the engine speed and the engine speed). The engine load is determined based on whether or not the engine is in the same operating range for a predetermined time or more.

  If it is determined in step 201 that the engine 11 has been warmed up, and it is determined in step 202 that the engine 11 is in steady operation, the process proceeds to step 203 and the target cooling water temperature shown in FIG. The target coolant temperature corresponding to the engine operating state [for example, engine speed and engine load (intake air amount, intake pipe negative pressure, throttle opening, etc.)] is calculated.

  Thereafter, the process proceeds to step 204, where the valve opening characteristic of the electronic thermostat 18 depends on whether the absolute value of the deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 and the target cooling water temperature is equal to or greater than a predetermined determination value. Determine if it has changed. The process of step 204 serves as valve opening characteristic change determining means in the claims.

  If it is determined in step 204 that the valve opening characteristic of the electronic thermostat 18 has changed (the absolute value of the deviation between the actual cooling water temperature and the target cooling water temperature is greater than or equal to the determination value), the process proceeds to step 205. Whether or not the cooling system is normal, for example, based on the diagnosis results of various abnormality diagnosis routines (not shown), the W / P 12, the electric cooling fan 19, the cooling water temperature sensor 21, etc. are all normal (no abnormality). Judgment is made by whether or not there is.

  If it is determined in step 205 that the cooling system is normal (the W / P 12, the electric cooling fan 19, the cooling water temperature sensor 21, etc. are all normal), the process proceeds to step 206, where the actual temperature detected by the cooling water temperature sensor 21 is detected. The heater energization power is F / B controlled so that the cooling water temperature matches the target cooling water temperature. In this case, for example, the F / B correction amount of the heater energization power is calculated by PID control or the like so that the deviation between the actual cooling water temperature and the target cooling water temperature becomes small.

  Thereafter, the process proceeds to step 207, where it is determined whether or not the absolute value of the deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 and the target cooling water temperature has become a predetermined value or less, and the actual cooling water temperature and the target cooling water temperature are determined. If it is determined that the absolute value of the deviation is larger than the predetermined value, the process returns to step 206, and the F / B control of the heater energizing power is continued.

  Thereafter, when it is determined in step 207 that the absolute value of the deviation between the actual cooling water temperature and the target cooling water temperature has become equal to or less than a predetermined value, it is determined that the actual cooling water temperature substantially matches the target cooling water temperature, Proceeding to 208, the current F / B correction amount of the heater energizing power is learned as the learning correction amount of the heater energizing power, and is common to all operation regions stored in a rewritable nonvolatile memory such as a backup RAM of the ECU 28. The learning correction amount learning data is updated with the current learning data. Alternatively, the learning data of the learning correction amount in the current learning area (the learning area corresponding to the current engine operating state) stored in the rewritable nonvolatile memory such as the backup RAM of the ECU 28 is updated with the current learning data. (Update the learning correction amount map). The processing in step 208 serves as learning correction means in the claims.

  In the first embodiment described above, whether or not the absolute value of the deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 during the steady operation after the engine 11 is warmed up and the target cooling water temperature is equal to or greater than a predetermined determination value. Thus, it is determined whether or not the valve opening characteristic of the electronic thermostat 18 has changed. When it is determined that the valve opening characteristic has changed, the actual cooling water temperature detected by the cooling water temperature sensor 21 is set to the target cooling water temperature. The heater energization power is F / B controlled so as to match. Thereafter, when it is determined by the F / B control that the actual cooling water temperature substantially matches the target cooling water temperature, the F / B correction amount of the heater energization power is learned as the learning correction amount of the heater energization power. By correcting the heater energization power calculated according to the engine operating state using this learning correction amount, the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics is reduced. Thus, the heater energization power is corrected. Thereby, even if the valve opening characteristic of the electronic thermostat 18 changes, the cooling water temperature can be accurately controlled to the target cooling water temperature, and fuel consumption deterioration and overheating due to a decrease in the cooling water temperature control accuracy can be prevented. .

  Generally, before the warm-up of the engine 11 is completed (during warm-up control), the valve 18a of the electronic thermostat 18 is maintained in the closed state, so that even if the valve opening characteristic of the electronic thermostat 18 is changed, the influence is changed. However, it hardly appears in a parameter (for example, cooling water temperature) for determining a change in the valve opening characteristic. Further, during the transient operation in which the engine operation state (for example, the engine rotation speed or the engine load) changes, the target cooling water temperature, the flow rate of the cooling water, and the like are not stable. Therefore, it is difficult to accurately determine whether or not the valve opening characteristic has changed before the engine 11 has been warmed up or during transient operation.

  In consideration of such circumstances, in the first embodiment, it is determined whether or not the valve opening characteristic has changed during the steady operation after the engine 11 is warmed up. Therefore, the valve opening of the electronic thermostat 18 is determined. The valve opening characteristic changes when the influence of the change in the valve characteristic is likely to appear in the parameter for judging the change in the valve opening characteristic (for example, the cooling water temperature) and the parameter for judging the change in the valve opening characteristic is stable. It is possible to determine whether or not the change has occurred, and it is possible to accurately detect a change in the valve opening characteristics.

  In the first embodiment, since the F / B correction amount of the heater energization power is learned as the learning correction amount of the heater energization power, after learning the learning correction amount of the heater energization power, the learning correction amount By correcting the heater energization power using, the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics can be reduced.

  As shown in FIG. 6, when the lift amount of the valve 18a changes due to a change in the valve opening characteristic of the electronic thermostat 18 (the deviation between the actual lift amount and the target lift amount increases), the radiator 13 is accordingly changed. The flow rate of the circulating cooling water changes, and the cooling water temperature changes. Accordingly, there is a correlation between the flow rate of the cooling water circulating to the radiator 13 and the cooling water temperature when the lift amount of the valve 18a changes due to the change in the valve opening characteristics.

  Therefore, in the second embodiment, a radiator flow sensor (not shown) for detecting the flow rate of the cooling water flowing through the radiator 13 is provided on the inlet side or the outlet side of the radiator 13, and the actual flow rate detected by the radiator flow sensor is It is determined whether or not the valve opening characteristic of the electronic thermostat 18 has changed depending on whether or not the absolute value of the deviation from the target flow rate is greater than or equal to a predetermined determination value. When the lift amount of the valve 18a changes due to the change in the valve opening characteristics of the electronic thermostat 18, the flow rate of the cooling water circulating to the radiator 13 changes accordingly. Therefore, the actual flow rate and the target flow rate detected by the radiator flow rate sensor Can be accurately determined whether or not the valve opening characteristic has changed.

  Further, paying attention to the fact that there is a correlation between the flow rate of the cooling water circulating in the radiator 13 and the cooling water temperature, when it is determined that the valve opening characteristic of the electronic thermostat 18 has changed, the radiator flow rate sensor F / B control of the heater energizing power so that the detected actual flow rate coincides with the target flow rate so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics. The heater energizing power is corrected. Thereafter, when it is determined by the F / B control that the actual cooling water temperature substantially matches the target cooling water temperature, the F / B correction amount of the heater energization power is learned as the learning correction amount of the heater energization power. By correcting the heater energizing power using the learning correction amount, the heater energizing power is corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics.

  In the second embodiment described above, substantially the same effects as those of the first embodiment can be obtained.

  As described above, when the lift amount of the valve 18a changes due to the change in the valve opening characteristic of the electronic thermostat 18 (the deviation between the actual lift amount and the target lift amount becomes large), it circulates to the radiator 13 accordingly. The cooling water flow rate changes and the cooling water temperature changes.

  Further, as shown in FIG. 10A, when W / P 12 is a mechanical W / P, the lift of the valve 18a is caused by a change in the valve opening characteristic of the electronic thermostat 18 even if the rotation speed of the W / P 12 is constant. When the amount changes (the deviation between the actual lift amount and the target lift amount increases), the pressure loss of the entire cooling water circulation passage changes accordingly, and the flow rate of the cooling water on the discharge port side of the W / P 12 changes. Change.

  On the other hand, as shown in FIG. 10B, in the case of the electric W / P of W / P12, even if the power consumption of W / P12 is constant, the lift of the valve 18a is caused by the change of the valve opening characteristic of the electronic thermostat 18. When the amount changes (the deviation between the actual lift amount and the target lift amount increases), the pressure loss of the entire cooling water circulation passage changes accordingly, and the flow rate of the cooling water on the discharge port side of the W / P 12 changes. Change.

  Therefore, when the W / P 12 is either mechanical W / P or electric W / P, when the lift amount of the valve 18a changes due to the change of the valve opening characteristic, the W / P 12 on the outlet side of the W / P 12 is changed. There is a correlation between the flow rate of the cooling water and the cooling water temperature.

  Therefore, in the third embodiment, a pump discharge port side flow sensor (not shown) for detecting the flow rate of cooling water is provided on the W / P 12 discharge port side, and the actual flow rate detected by this pump discharge port side flow sensor. Whether or not the valve opening characteristic of the electronic thermostat 18 has changed is determined based on whether or not the absolute value of the deviation from the target flow rate is greater than or equal to a predetermined determination value. When the lift amount of the valve 18a changes due to the change in the valve opening characteristics of the electronic thermostat 18, the pressure loss of the entire cooling water circulation passage changes accordingly, and the flow rate of the cooling water on the discharge port side of the W / P 12 changes. Therefore, if the deviation between the actual flow rate detected by the pump discharge side flow rate sensor and the target flow rate is monitored, it can be accurately determined whether or not the valve opening characteristic has changed.

  Further, paying attention to the fact that there is a correlation between the flow rate of the cooling water on the discharge port side of the W / P 12 and the cooling water temperature, when it is determined that the valve opening characteristic of the electronic thermostat 18 has changed, the pump The heater energization power is F / B controlled so that the actual flow rate detected by the discharge port side flow rate sensor matches the target flow rate, so that the deviation between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics (the cooling water temperature The heater energization power is corrected so as to reduce the deviation. Thereafter, when it is determined by the F / B control that the actual cooling water temperature substantially matches the target cooling water temperature, the F / B correction amount of the heater energization power is learned as the learning correction amount of the heater energization power. By correcting the heater energizing power using the learning correction amount, the heater energizing power is corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics.

  In the third embodiment described above, substantially the same effects as those of the first embodiment can be obtained.

  As described above, when the lift amount of the valve 18a changes due to the change in the valve opening characteristic of the electronic thermostat 18 (the deviation between the actual lift amount and the target lift amount becomes large), it circulates to the radiator 13 accordingly. The cooling water flow rate changes and the cooling water temperature changes.

  Further, as shown in FIG. 11, when the lift amount of the valve 18a changes due to the change in the valve opening characteristic of the electronic thermostat 18 (the deviation between the actual lift amount and the target lift amount increases), the cooling is performed accordingly. The pressure loss of the entire water circulation channel changes, and the pressure difference before and after W / P12 (the pressure difference between the pressure of the cooling water on the discharge port side of W / P12 and the pressure of the cooling water on the suction port side of W / P12) Changes.

  Therefore, when the lift amount of the valve 18a changes due to the change in the valve opening characteristics of the electronic thermostat 18, there is a correlation between the pressure difference before and after the W / P 12 and the cooling water temperature.

  In the fourth embodiment, therefore, a pump discharge side pressure sensor (not shown) for detecting the pressure of the cooling water is provided on the discharge port side of the W / P 12, and the cooling water is provided on the suction port side of the W / P 12. A pump suction side pressure sensor (not shown) for detecting the pressure of the coolant is provided, and the pressure of the cooling water on the discharge side of the W / P 12 detected by the pump discharge side pressure sensor and the pump suction side pressure sensor are detected. The actual pressure difference before and after W / P12 is obtained by calculating the pressure difference with the cooling water pressure on the inlet side of W / P12, and the absolute difference between the actual pressure difference before and after W / P12 and the target pressure difference is obtained. It is determined whether or not the valve opening characteristic of the electronic thermostat 18 has changed depending on whether or not the value is equal to or greater than a predetermined determination value. When the lift amount of the valve 18a changes due to the change of the valve opening characteristics of the electronic thermostat 18, the pressure loss of the entire cooling water circulation passage changes accordingly, and the pressure difference before and after the W / P 12 changes. By monitoring the deviation between the actual pressure difference before and after / P12 and the target pressure difference, it can be accurately determined whether or not the valve opening characteristic has changed.

Further, paying attention to the correlation between the pressure difference before and after the W / P 12 and the cooling water temperature, when it is determined that the valve opening characteristic of the electronic thermostat 18 has changed, the actual value before and after the W / P 12 F / B control of the heater energizing power so that the pressure difference matches the target pressure difference, so that the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics is reduced. Correct the heater energization power. Thereafter, when it is determined by the F / B control that the actual cooling water temperature substantially matches the target cooling water temperature, the F / B correction amount of the heater energization power is learned as the learning correction amount of the heater energization power. By correcting the heater energizing power using the learning correction amount, the heater energizing power is corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics.
In the fourth embodiment described above, substantially the same effects as those of the first embodiment can be obtained.

  In each of the first to fourth embodiments, the F / B correction amount of the heater energizing power is learned as the learning correction amount of the heater energizing power, and learning correction is performed to correct the heater energizing power using the learning correction amount. However, the learning correction is omitted, and the heater is configured to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change of the valve opening characteristic only by the F / B control of the heater energization power. The energized power may be corrected.

  In the present invention, it is not always necessary to perform the F / B control of the heater energization power. For example, the correction amount corresponding to the steady deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 and the target cooling water temperature is mapped. Alternatively, the heater is calculated by using mathematical formulas, etc., and by correcting the heater energizing power using this correction amount, the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics is reduced. The energized power may be corrected.

  Further, in each of the first to fourth embodiments, the heater energization power is corrected when it is determined that the valve opening characteristic has changed, but the function of determining whether or not the valve opening characteristic has changed is provided. The heater energization power may be corrected based on the deviation between the actual cooling water temperature detected by the cooling water temperature sensor 21 and the target cooling water temperature.

  Further, in each of the first to fourth embodiments, the heater energizing power calculated using the heater energizing power map is corrected. However, the heater energizing power map is corrected and the corrected map is used. By calculating the heater energizing power, the heater energizing power may be corrected so as to reduce the deviation (cooling water temperature deviation) between the cooling water temperature and the target cooling water temperature due to the change in valve opening characteristics.

  In addition, the present invention can be implemented with various modifications within a range that does not depart from the gist, such as appropriately changing the configuration of the cooling system.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... W / P (water pump), 13 ... Radiator, 16 ... Cooling water circulation circuit, 17 ... Bypass flow path, 18 ... Electronic thermostat, 18a ... Valve, 18b ... Heater, 21 ... Cooling Water temperature sensor, 28... ECU (heater control means, correction means, valve opening characteristic change determination means, learning correction means)

Claims (6)

An electronic thermostat having a valve for switching between a flow path for circulating cooling water of an internal combustion engine to a radiator and a flow path for not circulating to the radiator, and a heater for adjusting a cooling water temperature region where the valve opens In a control device for a vehicle cooling system,
A cooling water temperature sensor for detecting the cooling water temperature;
Heater control means for controlling the cooling water temperature to the target cooling water temperature by controlling the energization power of the heater of the electronic thermostat according to the operating state of the internal combustion engine and adjusting the cooling water temperature region where the valve of the electronic thermostat opens. ,
A valve opening characteristic change determining means for determining whether or not the valve opening characteristic of the electronic thermostat has changed,
The heater control means has correction means for correcting the energization power of the heater set according to the operating state of the internal combustion engine based on a deviation between the coolant temperature detected by the coolant temperature sensor and the target coolant temperature,
The control device for a vehicle cooling system, wherein the correction means corrects the energization power of the heater when the valve opening characteristic change determination means determines that the valve opening characteristic has changed. 2. The vehicle cooling system control according to claim 1, wherein the correction unit feedback corrects the energization power of the heater so that the cooling water temperature detected by the cooling water temperature sensor coincides with the target cooling water temperature. apparatus. An electronic thermostat having a valve for switching between a flow path for circulating cooling water of an internal combustion engine to a radiator and a flow path for not circulating to the radiator, and a heater for adjusting a cooling water temperature region where the valve opens In a control device for a vehicle cooling system,
A flow rate sensor for detecting a flow rate of cooling water flowing through the radiator or a flow rate of cooling water on a discharge port side of a water pump for circulating the cooling water;
Heater control means for controlling the cooling water temperature to the target cooling water temperature by controlling the energization power of the heater of the electronic thermostat according to the operating state of the internal combustion engine and adjusting the cooling water temperature region where the valve of the electronic thermostat opens. ,
A valve opening characteristic change determining means for determining whether or not the valve opening characteristic of the electronic thermostat has changed,
The heater control means includes correction means for correcting the energization power of the heater set according to the operating state of the internal combustion engine based on a deviation between a flow rate detected by the flow sensor and a target flow rate, An apparatus for controlling a cooling system for a vehicle, wherein when the valve opening characteristic change determining means determines that the valve opening characteristic has changed, the energization power of the heater is corrected. An electronic thermostat having a valve for switching between a flow path for circulating cooling water of an internal combustion engine to a radiator and a flow path for not circulating to the radiator, and a heater for adjusting a cooling water temperature region where the valve opens In a control device for a vehicle cooling system,
A pressure difference detecting means for detecting a pressure difference between the pressure of the cooling water on the discharge port side of the water pump for circulating the cooling water and the pressure of the cooling water on the suction port side of the water pump;
Heater control means for controlling the cooling water temperature to the target cooling water temperature by controlling the energization power of the heater of the electronic thermostat according to the operating state of the internal combustion engine and adjusting the cooling water temperature region where the valve of the electronic thermostat opens. ,
A valve opening characteristic change determining means for determining whether or not the valve opening characteristic of the electronic thermostat has changed,
The heater control means includes correction means for correcting the energization power of the heater set according to the operating state of the internal combustion engine based on a deviation between a pressure difference detected by the pressure difference detection means and a target pressure difference,
The control device for a vehicle cooling system, wherein the correction means corrects the energization power of the heater when the valve opening characteristic change determination means determines that the valve opening characteristic has changed. (1) a cooling water temperature sensor for detecting a cooling water temperature, (2) a flow rate sensor for detecting a flow rate of cooling water flowing through the radiator or a cooling water flow rate at a discharge port side of a water pump for circulating the cooling water, (3) At least one of pressure difference detecting means for detecting a pressure difference between the pressure of the cooling water on the discharge port side of the water pump and the pressure of the cooling water on the suction port side of the water pump;
The valve opening characteristic change determining means determines whether or not the valve opening characteristic has changed based on a deviation between a detected value of any one of the cooling water temperature sensor, the flow rate sensor, and the pressure difference detecting means and a target value. The control device for a vehicle cooling system according to claim 3 or 4 , wherein: The valve opening characteristic change determination means according to any one of claims 3 to 5, wherein the determining whether the valve opening characteristics change during steady operation after warm-up of the internal combustion engine Control device for vehicle cooling system.

Images