WO2018016486A1

WO2018016486A1 - Internal combustion engine control device and control method

Info

Publication number: WO2018016486A1
Application number: PCT/JP2017/025968
Authority: WO
Inventors: 裕一外山; 村井　淳; 坂口　重幸
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2016-07-19
Filing date: 2017-07-18
Publication date: 2018-01-25
Also published as: JP2018013056A

Abstract

According to the present invention, a control unit, which corrects the fuel injection amount of an internal combustion engine on the basis of a wall temperature estimation value (wall temperature detection value), corrects the wall temperature estimation value (wall temperature detection value) by changing the wall temperature estimation value (wall temperature detection value) to the same value as a cooling water temperature detection value when it is determined that the period of time that has elapsed since the start of idling stop has reached such a convergence time period as to allow a temperature difference between the cooling water temperature of the internal combustion engine and the wall temperature of a combustion chamber to be deemed to converge at substantially zero.

Description

Control device and control method for internal combustion engine

The present invention relates to a control device and a control method for an internal combustion engine.

In a conventional control device and control method for an internal combustion engine, a wall temperature of a cylinder is detected or estimated as a combustion chamber temperature, and a target air-fuel ratio and an actual air-fuel ratio that are calculated based on the detected value or estimated value of the wall temperature. There has been proposed one that corrects the fuel injection amount based on the ratio (for example, see Patent Document 1).

JP 2007-231834 A

However, a detection error or estimation error may occur in the detected value or estimated value of the wall temperature due to various factors, and the detected value or estimated value of the wall temperature may deviate from the actual combustion chamber temperature. Therefore, since the fuel injection amount corrected using the detected value or estimated value of the wall temperature can deviate from the fuel injection amount suitable for the actual combustion chamber temperature, particularly when the internal combustion engine is restarted. Exhaust properties, fuel consumption rate, and drivability may be reduced.

Therefore, in view of the above problems, the present invention improves the detection accuracy of the wall temperature detected as the combustion chamber temperature of the internal combustion engine, and improves the estimation accuracy of the wall temperature estimated as the combustion chamber temperature of the internal combustion engine. It is an object of the present invention to provide a control device and a control method for an internal combustion engine.

For this reason, the control apparatus and control method for an internal combustion engine according to the present invention corrects control parameters related to the control of the internal combustion engine based on the wall temperature of the combustion chamber detected or estimated as the temperature related to the combustion chamber of the internal combustion engine. Yes, the detected value or estimated value of the wall temperature used for correcting the control parameter is corrected based on the detected value of the coolant temperature of the internal combustion engine when combustion in the combustion chamber is stopped.

According to the control device and control method for an internal combustion engine of the present invention, it is possible to improve the detection accuracy of the wall temperature detected as the temperature in the combustion chamber of the internal combustion engine, and the combustion estimated as the temperature in the combustion chamber of the internal combustion engine The estimation accuracy of the wall temperature of the room can be improved.

It is the schematic which shows an example of the internal combustion engine for vehicles in 1st Embodiment. It is explanatory drawing which shows the correction principle of the wall temperature estimated value (detection value) in the embodiment. It is a flowchart which shows the calculation correction | amendment process of the wall temperature estimated value in the embodiment. It is a flowchart which shows the modification of FIG. 3 in the embodiment. It is explanatory drawing which shows the convergence time set according to the flow volume of the cooling water in the embodiment. It is explanatory drawing which shows the relationship between the flow volume of the cooling water in the same embodiment, and convergence time. It is a flowchart which shows the calculation correction process by the 1st modification of the embodiment. It is a flowchart which shows the calculation correction process by the 2nd modification of the embodiment. It is a flowchart which shows the calculation correction process by the 3rd modification of the embodiment. It is the schematic which shows an example of the internal combustion engine for vehicles in 2nd Embodiment. It is a flowchart which shows the acquisition correction process of the wall temperature detection value in the embodiment. It is a flowchart which shows the acquisition correction process by the 1st modification of the embodiment. It is a flowchart which shows the acquisition correction process by the 2nd modification of the embodiment. It is a flowchart which shows the acquisition correction process by the 3rd modification of the embodiment. It is a flowchart which shows the acquisition correction process by the 4th modification of the embodiment. It is explanatory drawing which shows the estimation (detection) error of a wall temperature estimation (detection) value.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
[First Embodiment]
FIG. 1 shows an example of an internal combustion engine to which a control device according to a first embodiment of the present invention is applied.
The internal combustion engine 1 is a power source mounted on a vehicle and includes a fuel injection valve 4 in an intake pipe (intake port) 3 upstream of the intake valve 2 of each cylinder. The fuel injection valve 4 is controlled so as to inject fuel intermittently into the intake pipe 3 by matching the injection timing with the stroke of each cylinder. The fuel stored in the fuel tank 5 is pumped to the fuel injection valve 4 by an electric fuel pump 6 disposed in the fuel tank 5.

Fuel injected by the fuel injection valve 4 into the intake pipe 3 is sucked into the combustion chamber 7 together with air through the intake valve 2 to form an air-fuel mixture. The air-fuel mixture in the combustion chamber 7 is ignited and burned by spark ignition by the spark plug 8. The combustion gas in the combustion chamber 7 is discharged to the exhaust pipe 10 through the exhaust valve 9.

The electronic control throttle 11 adjusts the intake air amount of the internal combustion engine 1 by changing the opening degree by the throttle motor 12. The electronic control throttle 11 is disposed in an intake duct common to each cylinder upstream of the portion of the intake pipe 3 where the fuel injection valve 4 is disposed.

Cooling water discharged through the water jacket 13 around the combustion chamber 7 of the internal combustion engine 1 is guided to a radiator 16 provided with an electric radiator fan 15 via a first cooling water passage 14. It is burned. When the cooling water guided to the radiator 16 passes through the radiator core to which the fins are attached, the temperature of the cooling water is reduced by exchanging heat with the outside air, such as forced cooling air generated by the rotation of the radiator fan 15. To do. Then, the cooling water whose temperature has decreased is returned to the water jacket 13 of the internal combustion engine 1 through the second cooling water passage 17.

Further, the first cooling water passage 14 and the second cooling water passage 17 are connected to each other by a bypass passage 18 so that the cooling water discharged from the internal combustion engine 1 bypasses the radiator 16. An electric thermostat 19 that opens and closes the passage area of the bypass passage 18 from fully open to fully closed in a stepwise or continuous manner is disposed at a joint portion between the bypass passage 18 and the second cooling water passage 17. The opening degree of the electric control thermostat 19 is controlled by inputting an external control signal, and the flow rate of the cooling water passing through the radiator 16 is changed.

A mechanical water pump (not shown) that circulates cooling water between the internal combustion engine 1 and the radiator 16 between the internal combustion engine 1 and the electric thermostat 19 in the second cooling water passage 17; Electric water pumps 20 are respectively provided. A mechanical water pump (not shown) is attached to a cooling water inlet of the internal combustion engine 1 and is driven by using a rotational force generated in the internal combustion engine 1, such as a cam shaft. The electric water pump 20 is driven by an electric motor 21 which is a drive source different from the internal combustion engine 1 so that the electric water pump 20 can be driven even when the internal combustion engine 1 is stopped by an idling stop function.

The control unit 22 including a microcomputer inputs output signals from various sensors that detect the operating state of the internal combustion engine 1. As various sensors, a water temperature sensor 23 for detecting the water temperature TW of the cooling water discharged from the internal combustion engine 1, an intake air temperature sensor 24 for detecting the intake air temperature TA of the internal combustion engine 1, and an intake air flow rate QA of the internal combustion engine 1 are detected. An air flow sensor 25 that detects the fuel supply pressure PF from the fuel pump 6, a pump rotation sensor 27 that detects the rotational speed NP of the electric water pump 20, an outside air temperature sensor 28 that detects the outside air temperature TE, and an internal combustion engine An engine rotation sensor 29 for detecting the engine rotation speed NE, a vehicle speed sensor 30 for detecting the vehicle speed V, an oil temperature sensor 31 for detecting the oil temperature TO of the lubricating oil of the internal combustion engine 1, and the depression amount of the accelerator pedal (accelerator opening) Degree) An accelerator opening sensor 32 for detecting ACC is included.

The control unit 22 controls the fuel injection amount and injection timing by the fuel injection valve 4, the ignition timing by the spark plug 8, the opening degree of the electronic control throttle 11, and the like based on output signals from various sensors. Further, the control unit 22 controls the rotation speed of the electric water pump 20 and the radiator fan 15 so as to adjust the coolant temperature to a temperature according to the operating state of the internal combustion engine 1 based on the output signal from the water temperature sensor 23. The rotational speed, the opening degree of the electric control thermostat 19 and the like are controlled. Thus, the control unit 22 constitutes a control device for the internal combustion engine 1.

Here, the control unit 22 determines the inner wall of the combustion chamber 7 as the temperature (combustion chamber temperature) related to the combustion chamber 7 of the internal combustion engine 1 based on output signals from the water temperature sensor 23, the oil temperature sensor 31, the intake air temperature sensor 24, and the like. Estimate the wall temperature at. Furthermore, the control unit 22 includes a control parameter correction unit that corrects control parameters related to control of the internal combustion engine 1 such as, for example, fuel injection amount, injection timing, and ignition timing, based on the estimated wall temperature (wall temperature estimated value). It is out. The control unit 22 controls the internal combustion engine 1 based on the corrected control parameter. For example, the control unit 22 sets and outputs an injection pulse signal for controlling the injection operation by the fuel injection valve 4 based on the corrected fuel injection amount and the corrected injection timing. In addition, for example, the control unit 22 controls energization to an ignition coil (not shown) so that spark discharge by the spark plug 8 is performed based on the corrected ignition timing. The control parameters relating to the control of the internal combustion engine 1 may also include actuator control parameters used in control such as VTC (Valve Timing Control), EGR (Exhaust Gas Recirculation), VCR (Variable Compression Ratio).

By the way, as shown in FIG. 16, the estimated wall temperature calculated by the control unit 22 includes a change in the operating state of the internal combustion engine 1 (for example, the vehicle is decelerated / stopped from constant speed driving of the vehicle and After that, an estimation error occurs due to various factors such as acceleration operation), individual differences of the internal combustion engine 1 or the external environment. For this reason, the estimated wall temperature may deviate from the actual wall temperature TC. Therefore, when the control unit 22 immediately corrects a control parameter (for example, fuel injection amount) related to the control of the internal combustion engine 1 using the estimated wall temperature value, the corrected control parameter is also suitable for the actual combustion chamber temperature. Since it may deviate from the control parameters, the exhaust properties, fuel consumption rate, and drivability of the internal combustion engine 1 may be reduced.

Therefore, as will be described later, the control unit 22 includes a wall temperature correction unit that corrects the estimated wall temperature based on the detected value (water temperature detected value) of the coolant temperature TW during idling stop. The wall temperature correction unit and the control parameter correction unit described above will be described as being executed by a computer that operates by reading a program stored in advance in a ROM (Read Only Memory) or the like of the control unit 22. However, the present invention is not limited to this, and part or all of the wall temperature correction unit and the control parameter correction unit can be realized by a hardware configuration.

Next, the principle of correcting the estimated wall temperature will be described.
FIG. 2 shows that when the vehicle decelerates and stops from high-load running and enters an idling stop state and then accelerates again, the wall temperature TC (see the broken line in the figure) and the water temperature TW (in the figure) It shows schematically how the reference (see solid line) changes.

In FIG. 2, since combustion stops in the combustion chamber 7 when the internal combustion engine 1 enters the idling stop state, the wall temperature TC in the combustion chamber 7 is equal to the water stop state in which cooling water flow is stopped during idling stop. descend. After the idling stop is started and the idling stop state continues for a certain time, the temperature difference between the water temperature TW and the wall temperature TC converges to substantially zero. Here, the convergence time t _r to the temperature difference between the water temperature TW and KabeAtsushi TC from the start of the idling stop converges to substantially zero becomes relatively long when the water stop state, the convergence time of the time when the t _r a t _rmax, when convergence time t _rmax from the start of idling stop has elapsed should the wall temperature TC and the water temperature TW is substantially coincident. For this reason, when there is a difference ΔD between the estimated wall temperature value (see the alternate long and short dash line in the figure) and the detected value of the water temperature TW, this difference ΔD can be regarded as an estimation error of the estimated wall temperature value. it can. Therefore, the control unit 22 stores in advance the convergence time _trmax obtained by experiments, simulations, etc. in a memory such as a ROM, so that when the convergence time _trmax has elapsed, the estimation error indicated by the difference ΔD is reduced. It is possible to correct the estimated wall temperature by removing it from the estimated temperature.

FIG. 3 shows an example of the calculation correction process for the estimated wall temperature value, which is repeatedly executed in the control unit 22 when the ignition switch is turned on.

In step S101 (abbreviated as S101 in the figure, the same applies hereinafter), the control unit 22 calculates the estimated wall temperature, the water temperature TW, the oil temperature TO, the amount of change in the intake air temperature TA, etc. calculated in step S101 executed previously. Based on the various parameters, a current estimated wall temperature value is calculated. Note that the control unit 22 assumes that the wall temperature TC coincides with the water temperature TW in the case of a cold start when the ignition switch is first turned on to execute step S101. The initial value of the estimated wall temperature may be the detected value of the water temperature TW.

In step S102, the control unit 22 determines whether or not to start idling stop. For example, based on output signals from the water temperature sensor 23, the vehicle speed sensor 30, and the like, the water temperature TW is equal to or higher than a temperature at which it is determined that the internal combustion engine 1 has been warmed up, and the vehicle speed V is a speed at which it is determined that the vehicle is stopped. In some cases, it can be determined to start idling stop. If the control unit 22 determines to start idling stop (Yes), the process proceeds to step S103. On the other hand, when the control unit 22 determines not to start the idling stop (No), the calculation correction process of the estimated wall temperature is terminated. When the internal combustion engine 1 is already in the idling stop state, the control unit 22 does not proceed from step S102 to step S103 and does not have to correct the estimated wall temperature. The same applies to the following embodiments and modifications thereof.

In step S103, the control unit 22 counts an IS time IST that is an elapsed time from the start of idling stop.
In step S104, the control unit 22 determines whether or not the IS time IST has reached the convergence time _trmax . Then, the control unit 22, when judging the IS time IST reaches the convergence time t _rmax is (Yes), it can be determined that the temperature difference between the water temperature TW and KabeAtsushi TC has converged substantially zero In order to correct the estimated wall temperature, the process proceeds to step S105. On the other hand, if the control unit 22 determines that the IS time IST has not reached the convergence time _trmax (No), the control unit 22 returns the process to step S103 to continue counting the IS time IST.

In step S105, the control unit 22 corrects the estimated wall temperature. Specifically, in step S105, the control unit 22 corrects the estimated wall temperature value by forcibly changing the current estimated wall temperature value to the same value as the detected value of the water temperature TW. Thereby, in step S101 performed next time, the control unit 22 calculates the next wall temperature estimated value based on the wall temperature estimated value from which the estimation error was removed in step S105.

In step S101, when the control unit 22 calculates the current estimated wall temperature for each calculation cycle without using the previously calculated estimated wall temperature, the following can be performed. Namely, as shown in FIG. 4, the control unit 22, in step S104, IS and time IST is determined to have reached the convergence time t _rmax (Yes), in step S104a, the detection value of the water temperature TW and the estimated wall temperature The difference ΔD from the value is calculated as a correction amount of the estimated wall temperature value. In step S105, the control unit 22 corrects the estimated wall temperature value by adding or subtracting the difference ΔD to the estimated wall temperature value calculated in step S101. When the control unit 22 determines in step S102 that the idling stop is not started (No), the control unit 22 advances the process to step S105 and calculates the estimated wall temperature based on the difference ΔD calculated in step S104a executed last time. Correct each time.

According to such a control unit 22, the temperature difference between the water temperature TW and the wall temperature TC in the internal combustion engine 1 converges to approximately zero in the water stop state from the start of the idling stop that stops the combustion in the combustion chamber 7. Since the estimated wall temperature value is corrected to the same value as the detected value of the water temperature TW when the convergence time _trmax, which is the time, has elapsed, the estimation accuracy of the estimated wall temperature value can be improved. Then, the control parameter suitable for the actual combustion chamber temperature is calculated by correcting the control parameter (for example, the fuel injection amount) related to the control of the internal combustion engine 1 using the wall temperature estimated value corrected in this way. This makes it possible to suppress a decrease in the exhaust properties, fuel consumption rate, and drivability of the internal combustion engine 1.

(First modification of the first embodiment)
Next, a first modification of the first embodiment will be described.
FIG. 5 shows how the wall temperature TC and the water temperature TW change with time when the vehicle decelerates / stops from a high-load running and enters an idling stop state and then accelerates again, as in FIG. It shows schematically how to do it. Changes in the wall temperature TC and the water temperature TW are different when the cooling water flow is stopped and when the cooling water is passed while idling is stopped. That is, when cooling water is passed during idling stop, the convergence is the time from the start of idling stop until the temperature difference between the water temperature TW (double solid line) and the wall temperature TC (double broken line) converges to substantially zero. When time t _r and t _r1, the convergence time t _r1, as described in FIG. 2, when the water stop of the cooling water in the idling stop, KabeAtsushi TC (dashed from the start of the idling stop coolant temperature TW (solid line) ) And the convergence time _trmax until the temperature difference converges to substantially zero. Accordingly, as shown in FIG. 6, in accordance with the flow rate of the cooling water is high during idling stop, you are possible to set the convergence time t _r gradually shortened to. Therefore, the control unit 22 according to a first modification of the first embodiment, with respect to operation and correction processing of the estimated wall temperature value in FIG. 3, the set value of the convergence time t _r in accordance with the flow rate of the cooling water in the idling stop Is changing.

FIG. 7 shows an example of the calculation correction process of the estimated wall temperature value that is repeatedly executed when the ignition switch is turned on in the control unit 22 according to the first modification of the first embodiment. In addition, about the same structure as 1st Embodiment, the description is abbreviate | omitted or simplified by attaching | subjecting the same code | symbol. The same applies hereinafter.

The calculation correction process of the estimated wall temperature value performed by the control unit 22 according to the first modification of the first embodiment is the same as the calculation correction process of the estimated wall temperature value of FIG. The difference is that step S102a is added in between.

In step S102a, the control unit 22 sets the convergence time t _r in accordance with the flow rate of the cooling water in the idling stop. For example, the convergence time _tr is set based on the detected value of the rotational speed NP of the electric water pump 20. When the rotational speed NP of the electric water pump 20 increases, the flow rate of the cooling water increases. Therefore, the convergence time _tr is set to be gradually shortened. On the other hand, when the rotational speed NP decreases, the flow rate of the cooling water is set. Therefore, the convergence time _tr is set to be gradually increased.

Specifically, the control unit 22 according to the first modification of the first embodiment uses a first data table in which the rotational speed NP of the electric water pump 20 and the convergence time _tr are correlated through an experiment or the like, such as a ROM. Store in advance in the storage means. Then, the control unit 22 refers to the first data table in performing step S102a, to set the convergence time t _r corresponding to the detected value of the rotation speed NP of the electric water pump 20. By thus changing the set value of the convergence time t _r in accordance with the flow rate of the cooling water in the idling stop, it is possible to shorten the time from idle stop start-up it is possible to correct the estimated wall temperature value .

(Second modification of the first embodiment)
Next, a second modification of the first embodiment will be described.
In the control unit 22 according to a second modification of the first embodiment, a flow rate of the cooling water in the idling stop as setting element of the convergence time t _r, with respect to a first modification of the first embodiment, the coolant temperature TW A water temperature / outside temperature difference ΔT, which is a temperature difference from the outside temperature TE, is added.

FIG. 8 shows an example of the calculation correction process of the estimated wall temperature value, which is repeatedly executed by the control unit 22 according to the second modification of the first embodiment when the ignition switch is turned on. The calculation correction process of the estimated wall temperature value executed by the control unit 22 according to the second modification of the first embodiment is different from the calculation correction process of the estimated wall temperature value of FIG. 7 in that step S102b is used instead of step S102a. It differs in the point to execute.

In step S102b, the control unit 22 calculates the water temperature / outside temperature difference ΔT calculated from the detected value of the rotational speed NP of the electric water pump 20, the detected value of the water temperature TW, and the detected value of the outside air temperature TE, Based on the above, the convergence time _tr is set.

If the outside air temperature TE decreases, that is, if the water temperature / outside air temperature difference ΔT increases, the amount of heat released from the cooling water in the radiator 16 increases and the rate of decrease in the wall temperature TC increases. On the other hand, if the outside air temperature TE rises, that is, if the water temperature / outside air temperature difference ΔT becomes small, the amount of heat released from the cooling water in the radiator 16 decreases, and the rate of decrease in the wall temperature TC becomes slow. Therefore, the convergence time _tr is gradually shortened as the rotational speed NP of the electric water pump 20 increases, and the rotational speed NP of the electric water pump 20 decreases as in the first modification of the first embodiment. In addition to setting the temperature gradually longer, the temperature is gradually shortened as the water temperature / outside air temperature difference ΔT becomes larger, and gradually set longer as the water temperature / outside air temperature difference ΔT becomes smaller.

Specifically, the control unit 22 according to a second modification of the first embodiment, the associating the rotational speed NP and the water temperature, the outside air temperature difference ΔT and the convergence time of the electric water pump 20 t _r by experiment or the like 2 The data table is stored in advance in storage means such as a ROM. Then, the control unit 22 refers to the second data table when executing step S102b, so that the convergence time corresponding to the detected value of the rotational speed NP of the electric water pump 20 and the calculated value of the water temperature / outside air temperature difference ΔT is obtained. Set _tr . By thus changing the set value of the convergence time t _r in accordance with the flow rate of the cooling water and the water temperature, the outside temperature difference ΔT in the idling stop, from the idling stop start-up it is possible to correct the estimated wall temperature value Time can be shortened more accurately than the first modification of the first embodiment.

(Third Modification of First Embodiment)
Next, a third modification of the first embodiment will be described.
In the control unit 22 according to the first modified example and the second modified example of the first embodiment described above, it converges according to the flow rate of cooling water during idling stop or according to this and the water temperature / outside air temperature difference ΔT. The time _tr was set. In contrast, the control unit 22 according to a third modification of the first embodiment, in order to further reduce the set value of the convergence time t _r, to change the flow rate of the cooling water in the idling stop at a relatively high flow rate . As a result, the idling stop is reduced before the temperature difference between the water temperature TW and the wall temperature TC converges to substantially zero, and a reduction in the correction frequency of the estimated wall temperature can be suppressed.

To intentionally shortening the convergence time t _r, for example, the control unit 22 according to the first and second modifications of the first embodiment is executed, the estimated wall temperature value in FIG. 7 or 8 In the calculation correction process, as shown in FIG. 9, step S102c can be added between step S102 and step S102a or step S102b. That is, if the control unit 22 determines in step S102 to start idling stop (Yes), in step S102c, the control unit 22 sets the rotational speed NP of the electric water pump 20 to make the flow rate of the cooling water relatively high. Increase. Then, the control unit 22, in step S102a or step S102b, the rotational speed NP was increased in step S102c, or sets the convergence time t _r in accordance with the the water temperature and outdoor air temperature difference ΔT this. In this case, in consideration of the time duration during which the rotational speed NP of the electric water pump 20 is increased at a constant rotational speed, the set value of the convergence time t _r may be corrected. The same applies to a third modification of the second embodiment to be described later.

[Second Embodiment]
Next, a control device according to a second embodiment of the present invention will be described.
FIG. 10 shows an example of an internal combustion engine 1A to which the control device according to the second embodiment is applied.
As shown in FIG. 10, the internal combustion engine 1A includes a wall temperature sensor 33 that detects the wall temperature TC of the combustion chamber 7, and an output signal from the wall temperature sensor 33 is used as a control unit 22A that constitutes a control device for the internal combustion engine 1A. This is different from the first embodiment in that it is input to. The control unit 22A determines control parameters (for example, fuel injection amount, injection timing, ignition timing, etc.) related to the control of the internal combustion engine 1A based on the detection value (wall temperature detection value) of the wall temperature TC detected by the wall temperature sensor 33. It is corrected. The wall temperature sensor 33 is arranged independently on the inner wall of the combustion chamber 7, and is integrally formed with the spark plug 8 and a fuel injection valve when fuel is directly injected into the combustion chamber 7. Also good.

Referring to FIG. 16 again, the wall temperature detection value includes variations in the linear output value and temperature characteristics of the wall temperature sensor 33, power supply voltage, A / D (Analog-to-Digital) conversion circuit, harness in the control unit 22A. Since detection errors may occur due to variations in connectors and the like, the wall temperature detection value may deviate from the wall temperature TC. Therefore, when the control unit 22A immediately corrects a control parameter (for example, fuel injection amount) related to the control of the internal combustion engine 1A using the detected wall temperature value, the corrected control parameter is suitable for the actual combustion chamber temperature. Since it may deviate from the control parameters, the exhaust property, fuel consumption rate, and drivability of the internal combustion engine 1A may be reduced.

Therefore, the control unit 22A corrects the detected wall temperature value detected by the wall temperature sensor 33 based on the detected value (water temperature detected value) of the water temperature TW during idling stop, as will be described later. The correction principle of the detected wall temperature value is the same as the corrected principle of the estimated wall temperature value described with reference to FIG. 2 in the first embodiment. Since it can be described as a detection error, it will be omitted.

FIG. 11 shows an example of the acquisition correction process of the detected wall temperature value that is repeatedly executed when the ignition switch is turned on in the control unit 22A.
In step S <b> 201, the control unit 22 </ b> A acquires the detected wall temperature value based on the output signal from the wall temperature sensor 33.
Steps S202 to S204 execute the same processes as steps S102 to S104 in the flowchart (see FIG. 3) showing an example of the calculation correction process of the estimated wall temperature by the control unit 22 of the first embodiment. Description is omitted.

If the control unit 22A determines in step S204 that the IS time IST has reached the convergence time _trmax (Yes), in step S205, the difference ΔD between the detected value of the water temperature TW and the detected wall temperature is detected as the wall temperature. Calculated as a value correction amount. In step S206, the control unit 22A corrects the detected wall temperature by adding or subtracting the difference ΔD to the detected wall temperature acquired in step S201. Further, when it is determined in step S202 that the idling stop is not started (No), the control unit 22A advances the process to step S206, and acquires the detected wall temperature value based on the difference ΔD calculated in step S205 of the previous execution. Correct in degrees.

According to such a control unit 22A, from the start of idling stop that stops combustion in the combustion chamber 7 until the temperature difference between the water temperature TW and the wall temperature TC in the internal combustion engine 1A converges to substantially zero in the water stop state. Since the difference ΔD between the detected value of the water temperature TW and the detected wall temperature is calculated and the detected wall temperature is corrected based on this difference ΔD when the convergence time _trmax, which is time, has elapsed, the wall temperature The detection accuracy of the detection value can be improved. Then, using the wall temperature detection value corrected in this way, a control parameter suitable for the actual combustion chamber temperature is calculated by correcting a control parameter (for example, fuel injection amount) related to the control of the internal combustion engine 1A. This makes it possible to suppress the deterioration of the exhaust properties, fuel consumption rate, and drivability of the internal combustion engine 1A.

(First Modification of Second Embodiment)
Next, a first modification of the second embodiment will be described.
As described with reference to FIGS. 5 and 6 in the first modification of the first embodiment, as the flow rate of the cooling water during the idling stop increases, the water temperature TW and the wall temperature TC are increased from the start of the idling stop. convergence time temperature difference is the time to converge to approximately zero t _r is shortened. Therefore, the control unit 22A according to a first modification of the second embodiment, with respect to obtaining correction processing wall temperature detection value of FIG. 11, by changing the convergence time t _r in accordance with the flow rate of the cooling water in the idling stop ing. By doing so, it is possible to shorten the time from the start of idling stop until the wall temperature detection value can be corrected.

FIG. 12 shows an example of a wall temperature detection value acquisition correction process that is repeatedly executed when the ignition switch is turned on in the control unit 22A according to the first modification of the second embodiment. The acquisition correction process of the detected wall temperature value performed by the control unit 22A according to the first modification of the second embodiment includes steps S202 and S203 as compared with the acquisition correction process of the detected wall temperature value in FIG. The difference is that step S202a is added in between.

In step S202a, the control unit 22A converges according to the detected value of the rotational speed NP of the electric water pump 20 during idling stop, similarly to step S102a (see FIG. 7) according to the first modification of the first embodiment. Time _tr is set. The other processes are the same as the wall temperature detection value acquisition correction process in FIG.

(Second Modification of Second Embodiment)
Next, a second modification of the second embodiment will be described.
In the control unit 22A according to a second modification of the second embodiment, as the setting element of the convergence time t _r, using the flow rate of the cooling water in the idling stop, relative to the first modification of the second embodiment, the water temperature TW Water temperature / outside air temperature difference ΔT, which is a temperature difference between the air temperature and the outside air temperature TE, is added.

FIG. 13 is a flowchart showing an example of a wall temperature detection value acquisition correction process repeatedly executed by the control unit 22A according to the second modification of the second embodiment when the ignition switch is turned on. The wall temperature detection value acquisition correction process executed by the control unit 22A according to the second modification of the second embodiment is different from the wall temperature detection value acquisition correction process of FIG. 12 in that step S202b is used instead of step S202a. It differs in the point to execute.

In step S202b, the control unit 22A detects the detected value of the rotational speed NP of the electric water pump 20 and the detected value of the water temperature TW, as in step S102b (see FIG. 8) according to the second modification of the first embodiment. And the convergence time _tr is set based on the calculated value of the water temperature / outside temperature difference ΔT calculated from the detected value of the outside temperature TE. The other processes are the same as the wall temperature detection value acquisition correction process in FIG.

(Third Modification of Second Embodiment)
Next, a third modification of the second embodiment will be described.
Control unit 22A according to a third modification of the second embodiment, similarly to the third modification of the first embodiment, the first and second modifications of the second embodiment, the convergence time t _r In order to further reduce the set value, the flow rate of the cooling water during idling stop is changed to a relatively high flow rate. Thereby, it can suppress that idling stop is complete | finished before wall temperature TC converges on water temperature TW, and the correction frequency of wall temperature detection value decreases.

For example, in the wall temperature detection value acquisition correction process of FIG. 12 or 13 executed by the control unit 22A according to the first modification and the second modification of the second embodiment, as shown in FIG. Step s202c can be added between Step S202a and Step s202b. That is, if it is determined in step S202 that the idling stop is started (Yes), the control unit 22A determines that the rotational speed NP of the electric water pump 20 is set to a relatively high flow rate in step S202c. Increase. Then, the control unit 22A in step S202a or step S202b, in accordance with the rotational speed NP that increased in step S202c, or depending on the water temperature, the outside temperature difference ΔT in addition, to set the convergence time t _r .

(Fourth modification of the second embodiment)
Next, a fourth modification of the second embodiment will be described.
The control unit 22A according to the fourth modified example of the second embodiment uses the wall temperature sensor 33 based on the detected wall temperature and the detected value of the water temperature TW when the convergence time _trmax has elapsed in the water stoppage state. Failure diagnosis processing for the wall temperature sensor 33 is performed to diagnose whether or not a failure has occurred.

FIG. 15 shows an example of failure diagnosis processing of the wall temperature sensor 33 that is repeatedly executed when the ignition switch is turned on in the control unit 22A according to the fourth modification of the second embodiment. Steps S301 to S303 are the same as steps S202 to S204 of the wall temperature detection value acquisition correction process in FIG.

The control unit 22A determines that the idling stop is started in Step S301 (Yes), and if it is further determined in Step S303 that the IS time IST has reached the convergence time _trmax (Yes), in Step S304, the wall temperature sensor 33 is determined. Set the threshold for failure diagnosis. Specifically, the control unit 22A calculates the upper limit threshold value TU by adding the detection error α of the wall temperature sensor 33 to the detected value of the water temperature TW, and calculates the upper limit threshold TU of the detected value of the water temperature TW. The lower limit threshold TL is calculated by subtracting the detection error α. The range from the upper limit threshold TU to the lower limit threshold TL is a normal range in which the wall temperature sensor 33 is diagnosed as normal.

In step S305, the control unit 22A determines whether or not the detected wall temperature is not less than the lower threshold TL and not more than the upper threshold TU. If the control unit 22A determines that the detected wall temperature is not less than the lower limit threshold TL and not more than the upper limit threshold TU (Yes), the process proceeds to step S306, and the wall temperature sensor 33 is normal. Diagnose. On the other hand, if the control unit 22A determines that the detected wall temperature value is less than the lower limit threshold value TL or greater than the upper limit threshold value TU (No), the process proceeds to step S307, and the wall temperature sensor 33 has failed. Diagnose. When the control unit 22A determines that the idling stop is not started in step S301, the failure diagnosis process for the wall temperature sensor 33 is not performed (No).

When the control unit 22A diagnoses that the wall temperature sensor 33 has failed, the control unit 22A sets a failure flag indicating a failure state from 0 to 1, for example, and stores it in a storage means such as a RAM (Random Access Memory). When the failure flag is set to 1, correction of the wall temperature detection value in the second embodiment including the first to third modifications is not performed, or depending on the wall temperature detection value The control parameter may not be corrected.

The control device and control method for an internal combustion engine according to the present invention have been specifically described above based on the first embodiment, the second embodiment, and their modifications (hereinafter referred to as embodiments). The present invention is not limited to the embodiment and the like, and various modifications can be made without departing from the scope of the invention. For example, the

control unit

22,22A is, to set the convergence time t _r in accordance with the flow rate of the cooling water is not limited to the detection value of the rotational speed of the electric water pump 20, for example, the measured values or the like of the cooling water flow rate, cooling Various parameters indicating the water flow rate can be used.

In the above embodiment and the like, the estimated wall temperature value and the detected wall temperature value have been described as being corrected based on the detected value of the water temperature TW when the internal combustion engine 1, 1A is in the idling stop state. The correction is not limited to when the fuel is in the state, but may be corrected based on the detected value of the water temperature TW when the fuel supply to the fuel injection valve 4 is shut off and the combustion in the combustion chamber 7 is stopped.

For example, the convergence time t _r to the temperature difference between the actual wall temperature TC and the water temperature TW of the cooling water from the stop of the combustion in the combustion chamber 7 at the time of deceleration of the vehicle (during engine braking) is converged to substantially zero _Assuming that t _r2 , when the convergence time _{tr 2} has elapsed, the estimated wall temperature value or the detected wall temperature value can be corrected to the same value as the detected value of the water temperature TW. When the vehicle is decelerated, the

internal combustion engine

1, 1 </ b> A rotates and the outside air is introduced into the combustion chamber 7, so that the convergence time _{tr 2} when the vehicle is decelerated is taken into consideration that the rate of decrease in the wall temperature TC increases. , etc. the engine speed NE is less than the convergence time t _rmax during idling stop is substantially zero, convergence time t _r during deceleration of the vehicle may be set according to the engine rotational speed NE.

Further, for example, when a convergence time t _rmax stop the internal combustion engine 1,1A and the ignition switch is turned off has elapsed, the temperature difference between the water temperature TW and KabeAtsushi TC has converged substantially zero Therefore, when the internal combustion engine 1, 1A is started with the ignition switch turned on, the estimated wall temperature value or the detected wall temperature value is the same as the detected value of the water temperature TW before combustion in the combustion chamber 7. Can be corrected. The

control units

22 and 22A are provided with a time measuring means (timer) for counting an elapsed time since the ignition switch is turned off, and this time measuring means is configured so that electric power is always supplied from an in-vehicle power source. The

In the above-described embodiment and the like, the convergence time _tr is changed according to the flow rate of the cooling water during idling stop or in addition to the water temperature / outside air temperature difference ΔT. In addition to these parameters or separately from these parameters, it can be changed according to the difference between the estimated wall temperature value at the start of the idling stop and the detected value of the water temperature TW.

For example, as the difference between the estimated wall temperature at the start of idling stop and the detected value of the water temperature TW increases, the time until the temperature difference between the water temperature TW and the wall temperature TC converges to approximately zero is estimated to increase. Runode, it may be set to a large convergence time t _r.

In the above embodiments, etc., when the convergence time t _r has elapsed from the start of the idling stop, the temperature difference between the water temperature TW and KabeAtsushi TC had determined that converges to substantially zero. However, when the flow rate of the cooling water or the flow rate of the cooling water passing through the radiator 16 fluctuates during the idling stop, the water temperature TW and the water temperature TW when the convergence time _tr elapses after the idling stop is started. The temperature difference from the wall temperature TC does not necessarily converge to substantially zero.

Therefore, instead of the convergence time t _r, for example, it may be used integrated flow rate of the cooling water that flows when to shut off the fuel supply to the fuel injection valve 4 has stopped the combustion in the combustion chamber 7. The integrated flow rate of the cooling water can be calculated based on the integrated value of the rotational speed NP of the electric water pump 20, for example. Then, the

control units

22 and 22A can determine whether or not the temperature difference between the water temperature TW and the wall temperature TC has converged to substantially zero based on the comparison result obtained by comparing the calculated integrated flow rate with the threshold value. In place of the convergence time t _r, for example, the integrated flow rate of the cooling water that is calculated based on the rotational speed NP to the integrated value of the correction rotation speed is corrected by opening the electrically controlled thermostat 19 of the electric water pump 20 using May be. Then, the

control units

22 and 22A can determine whether or not the temperature difference between the water temperature TW and the wall temperature TC has converged to substantially zero based on the comparison result obtained by comparing the calculated integrated flow rate with the threshold value. The threshold value is obtained as an integrated flow rate of the cooling water flowing until the temperature difference between the water temperature TW and the wall temperature TC converges to substantially zero while the combustion in the combustion chamber 7 is stopped by experiment or simulation. It is stored in advance in storage means such as a ROM of the

units

22 and 22A.

In the above embodiments, etc., when the convergence time t _r has elapsed from the start of the idling stop, i.e., the temperature difference between the water temperature TW and KabeAtsushi TC stop the combustion in the combustion chamber 7 is converged to substantially zero In the above description, it is assumed that the estimated wall temperature value or the detected wall temperature value is corrected at the timing when it is determined. Instead, in order to improve the correction frequency of the estimated wall temperature value or the detected wall temperature value, the estimated wall temperature value is determined before the temperature difference between the water temperature TW and the wall temperature TC has converged to substantially zero. Alternatively, the detected wall temperature value can be corrected.

For example, the

control unit

22,22A is previously stored temperature data wall temperature TC at each elapsed time from the start of the idling stop, a predetermined time before the elapsed convergence time t _r is from the start of idling stop In this case, the correction may be made by combining the estimated wall temperature value or the detected wall temperature value with the temperature data of the corresponding wall temperature TC. Note that the temperature data of the wall temperature TC at each elapsed time after the start of idling stop is obtained in advance by experiments or simulations.

DESCRIPTION OF SYMBOLS 1,1A ... Internal combustion engine 4 ... Fuel injection valve 7 ... Combustion chamber 20 ...

Electric water pump

22, 22A ... Control unit 23 ... Water temperature sensor 27 ... Pump rotation sensor 28 ... Outside temperature sensor 29 ... Engine rotation sensor 33 ... Wall temperature sensor TW ... Water temperature NP ... Rotation speed of electric water pump TE ... Outside air temperature NE ... Engine rotation speed TC ... Wall temperature _tr ... Convergence time

Claims

A control parameter correction unit that corrects a control parameter related to the control of the internal combustion engine based on the wall temperature of the combustion chamber detected or estimated as a temperature related to the combustion chamber of the internal combustion engine;
A wall temperature correction unit that corrects the detected or estimated wall temperature based on a detected value of the coolant temperature of the internal combustion engine when combustion in the combustion chamber is stopped;
A control apparatus for an internal combustion engine, comprising:
When the wall temperature correction unit determines that the temperature difference between the cooling water temperature and the actual wall temperature has converged to substantially zero, the detected or estimated wall temperature is the water temperature detection value of the cooling water. The control apparatus for an internal combustion engine according to claim 1, wherein the correction is made to have the same value as.
The wall temperature correction unit stores in advance a convergence time from when the combustion in the combustion chamber is stopped until the temperature difference between the coolant temperature and the actual wall temperature converges to substantially zero, and the convergence time The control apparatus for an internal combustion engine according to claim 2, wherein the detected or estimated wall temperature is corrected to the same value as a detected water temperature of the cooling water when the time elapses.
The control apparatus for an internal combustion engine according to claim 3, wherein the convergence time is set according to a flow rate of the cooling water.
5. The control apparatus for an internal combustion engine according to claim 4, wherein the convergence time is shortened as the flow rate of the cooling water increases.
The control apparatus for an internal combustion engine according to claim 3, wherein the convergence time is set according to a temperature difference between a water temperature and an outside air temperature of the cooling water and a flow rate of the cooling water. .
The control apparatus for an internal combustion engine according to claim 4, wherein the convergence time is further set according to an engine speed of the internal combustion engine.
5. The control apparatus for an internal combustion engine according to claim 4, wherein the wall temperature correction unit forcibly increases the flow rate of the cooling water to correct the detected or estimated wall temperature.
The said wall temperature correction | amendment part correct | amends the said wall temperature detected or estimated based on the water temperature detection value of the said cooling water when the said internal combustion engine is an idling stop state. Control device for internal combustion engine.
The said wall temperature correction | amendment part correct | amends the said detected or estimated wall temperature based on the water temperature detected value of the said cooling water when an ignition switch transfers to an ON state from an OFF state, The said wall temperature correction | amendment part correct | amends the detected or estimated wall temperature. The control apparatus of the internal combustion engine described in 1.
The wall temperature correction unit detects the wall temperature based on the wall temperature detected as the temperature related to the combustion chamber of the internal combustion engine and the detected water temperature of the cooling water when the convergence time has elapsed. The control device for an internal combustion engine according to claim 3, wherein a diagnosis is made as to whether or not a failure has occurred in the detecting unit.
The control apparatus for an internal combustion engine according to claim 11, wherein the wall temperature correction unit stops the correction of the detected wall temperature when it is diagnosed that a failure has occurred in the detection unit. .
The wall temperature correction unit corrects the detected or estimated wall temperature based on the detected water temperature of the cooling water before the temperature difference between the cooling water temperature and the actual wall temperature converges to substantially zero. The control apparatus for an internal combustion engine according to claim 1, wherein:
Based on the wall temperature of the combustion chamber detected or estimated as the temperature related to the combustion chamber of the internal combustion engine, the control parameter related to the control of the internal combustion engine is corrected,
Correcting the detected or estimated wall temperature based on the detected value of the coolant temperature of the internal combustion engine when combustion in the combustion chamber is stopped,
A method for controlling an internal combustion engine.