JP6833952B1 - Engine exhaust system temperature estimator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine exhaust system temperature estimation device capable of estimating an exhaust system temperature with high accuracy even when an EGR system is operated. SOLUTION: The temperature of the exhaust system in a steady operation state of an engine (1) stored in advance is provided for each operating condition with data when the EGR is not operating and data under a predetermined EGR rate condition, and EGR is provided. According to the change in the rate, the basic value of the exhaust system gas temperature during steady combustion is calculated from the data under the EGR rate condition including when the EGR is not operating, and the basic temperature value of the exhaust system during steady combustion is set according to the EGR rate. The temperature estimate of the exhaust system during steady combustion is calculated by correcting it with the correction amount based on the corrected ignition retard amount. [Selection diagram] Fig. 3

Description

The present application relates to an engine exhaust system temperature estimation device.

Conventionally, techniques for estimating the temperature in a specific part of the exhaust system of an engine such as an exhaust gas purification catalyst have been developed. For example, Patent Document 1 describes the intake air amount ratio indicating the ratio of the intake air amount to the reference intake air amount associated with the operating state of the engine, and the illustrated output in the operating state of the engine at that time. An engine exhaust temperature estimation device that calculates an estimated exhaust temperature by calculating a correction coefficient and using the calculated correction coefficient to correct the reference exhaust temperature associated with the steady operation state of the engine. Proposed.

Further, in Patent Document 2, the exhaust temperature of the engine flowing into the exhaust gas purification catalyst is estimated based on the engine rotation speed and the intake air amount, and the exhaust gas temperature is estimated in advance based on the engine rotation speed and the intake air amount. The estimated value of the exhaust temperature is subtracted from the set intra-layer temperature of the exhaust gas purification catalyst, the reaction heat of the exhaust gas purification catalyst is estimated based on this subtracted value, and the estimated value of the exhaust gas and the exhaust gas purification are used. An exhaust gas purification catalyst state estimation device has been proposed in which the intra-layer temperature of the exhaust gas purification catalyst is estimated by adding the estimated value of the reaction heat of the catalyst.

If a temperature sensor is used, it is possible to directly detect the exhaust temperature and the temperature of the exhaust gas purification catalyst, but this leads to an increase in cost and the time and effort required to install the temperature sensor. Extra is needed. Further, the exhaust system of the engine may lack the space for providing the temperature sensor.

Therefore, in reality, it is preferable to estimate the temperature of the exhaust system of the engine without using a temperature sensor. By estimating the temperature of the exhaust system of the engine, for example, if the temperature of the exhaust gas purification catalyst of the engine can be accurately estimated, it is possible to avoid the situation where the exhaust gas purification catalyst is deteriorated or damaged due to excessive heat. In addition, it is possible to implement the fuel increase control as a protection control for the exhaust gas purification catalyst under the minimum conditions without unnecessarily expanding it, which also contributes to the improvement of fuel efficiency. it can.

JP-A-2010-7492 Japanese Patent No. 6216244

The conventional device disclosed in Patent Document 1 estimates the exhaust gas temperature of an engine, and the conventional device disclosed in Patent Document 2 estimates the temperature of an exhaust gas purification catalyst. In the conventional device shown in 1, a reference value of the exhaust temperature of the engine during the steady operation of the engine is set, and various corrections are made to this reference value to obtain the estimated exhaust temperature during the steady operation of the engine. In the conventional device shown in Patent Document 2, a reference value of the catalyst reaction heat for purifying exhaust gas during steady operation of the engine is set, and various corrections are made to the reference value to make the engine steady. The estimated exhaust gas purification catalyst temperature during operation is calculated.

However, both the conventional devices disclosed in Patent Document 1 and Patent Document 2 are in an engine equipped with an EGR (Exhaust Gas Recirculation) system, and when the EGR system is activated, during intake of freshly inhaled gas. It does not take into consideration that the exhaust temperature during steady operation of the engine and the reaction heat of the exhaust gas purification catalyst will change depending on the amount of exhaust gas to be recirculated, and is the standard for the exhaust temperature when the EGR system is operating. The value is not set and the standard value of the catalyst reaction heat for exhaust gas purification is not set. Therefore, the correction of the reference value of the exhaust temperature during the operation of the EGR system and the correction of the reference value of the catalyst reaction heat for purifying the exhaust gas have not been carried out. Therefore, in the conventional apparatus disclosed in Patent Document 1 and Patent Document 2, when the EGR system is operated, there is an error between the reference value of the exhaust gas temperature during steady operation and the reference value of the catalyst reaction heat for purifying exhaust gas during steady operation. As a result, a large error may occur between the estimated exhaust gas temperature and the estimated exhaust gas purification catalyst temperature.

The present application discloses a technique for solving the above-mentioned problems, and provides an engine exhaust system temperature estimation device capable of estimating the exhaust system temperature with high accuracy even when the EGR system is activated. The purpose is to do.

The engine exhaust system temperature estimator disclosed in the present application is
An engine exhaust system that estimates the temperature of the engine exhaust system in an engine equipped with an EGR system that returns the exhaust gas discharged from the engine to the engine and an exhaust gas purification catalyst that purifies the exhaust gas of the engine. It is a temperature estimation device
An engine operating state detecting means for detecting an operating state of the engine including at least the rotational speed of the engine and the load of the engine.
An EGR rate detecting means for detecting an EGR rate controlled by the EGR system,
A first type that stores the temperature of the exhaust gas when the EGR system is not operating in the steady operation state of the engine as the first exhaust gas temperature basic data during steady combustion for each operating condition of the engine. Exhaust gas temperature storage means during steady combustion,
The temperature of the exhaust gas of the engine when the EGR system is operated at a predetermined EGR rate in the steady operation state of the engine is set to the exhaust during the second steady combustion for each operating condition of the engine. The second exhaust gas temperature storage means for steady combustion, which is stored as basic gas temperature data,
According to the change in the EGR rate, the first steady combustion exhaust gas temperature basic data stored in the first steady combustion exhaust gas temperature storage means and the second steady combustion exhaust gas temperature storage. Calculation of the basic value of the exhaust gas temperature during steady combustion corresponding to the current EGR rate based on the second basic data of the exhaust gas temperature during steady combustion stored in the means. Department and
An ignition retard amount correcting means that corrects the exhaust gas temperature basic value during steady combustion calculated by the exhaust gas temperature basic value calculation unit during steady combustion according to the ignition retard amount of the engine.
An EGR amount correction means that corrects the correction amount for correcting the exhaust gas temperature basic value during steady combustion by the ignition retard amount correction means according to the EGR rate.
The first averaging coefficient which is calculated based on the exhaust gas temperature response delay of the engine, before Symbol ignition retard quantity correction means and the EGR amount correction means and the corrected the steady combustion at the exhaust gas temperature basic value on the basis of the The combustion exhaust gas temperature estimation unit that outputs the estimated value of the exhaust gas temperature during steady combustion obtained by performing the first annealing treatment on the vehicle, and
With
It is configured to estimate the temperature of the exhaust system based on the estimated value of the exhaust gas temperature during steady combustion output from the exhaust gas temperature estimation unit during combustion.
It is characterized by that.

Further, the engine exhaust system temperature estimation device disclosed in the present application is
An engine exhaust system that estimates the temperature of the engine exhaust system in an engine equipped with an EGR system that returns the exhaust gas discharged from the engine to the engine and an exhaust gas purification catalyst that purifies the exhaust gas of the engine. It is a temperature estimation device
An engine operating state detecting means for detecting an operating state of the engine including at least the rotational speed of the engine and the load of the engine.
An exhaust gas temperature detecting means for detecting the temperature of the exhaust gas of the engine flowing into the exhaust gas purifying catalyst, or an exhaust gas temperature estimating means for estimating the temperature of the exhaust gas based on the operating state of the engine.
An EGR rate detecting means for detecting an EGR rate controlled by the EGR system,
Exhaust gas purification catalyst reaction heat when the engine is in a steady operation state and when the EGR system is not operating, and the first exhaust gas purification catalyst reaction heat basic data for each operating condition of the engine. The first catalyst reaction heat storage means for purifying exhaust gas during steady combustion, which is stored as
The reaction heat of the exhaust gas purification catalyst when the engine is operated at a predetermined EGR rate in the steady operation state of the engine is subjected to a second steady combustion for each operating condition of the engine. The second catalyst reaction heat storage means for purifying exhaust gas during steady combustion, which is stored as basic data, and the catalyst reaction heat storage means for purifying exhaust gas.
Based on the first basic data on the catalyst reaction heat for purifying exhaust gas during steady combustion and the second basic data on the catalyst reaction heat for purifying exhaust gas during steady combustion, according to the change in the EGR rate. Calculates the basic value of the catalyst reaction heat for purifying exhaust gas during steady combustion corresponding to the EGR rate.
Ignition retard amount correction means that corrects the catalyst reaction heat basic value for exhaust gas purification during steady combustion calculated by the calculation unit for the exhaust gas purification catalyst reaction heat during steady combustion according to the ignition retard amount of the engine. When,
The EGR amount correction means for correcting the correction amount for correcting the basic value of the catalyst reaction heat for purifying exhaust gas during steady combustion by the ignition retard amount correction means according to the EGR rate.
The exhaust gas during steady combustion is corrected based on the ignition retard amount correction means and the EGR amount correction means by the second smoothing coefficient calculated based on the catalyst reaction thermal response delay for purifying the exhaust gas of the engine. A catalyst reaction heat estimation unit for combustion exhaust gas purification that outputs an estimated value of the catalyst reaction heat for purification of exhaust gas during steady combustion obtained by performing a second annealing treatment on the basic value of the catalyst reaction heat for purification,
With
It is configured to estimate the temperature of the exhaust system based on the estimated value of the catalyst reaction heat for purifying exhaust gas during steady combustion output from the catalyst reaction heat estimation unit for purifying exhaust gas during combustion.
It is characterized by that.

According to the engine exhaust system temperature estimation device disclosed in the present application, the exhaust system temperature of the engine can be estimated with high accuracy even when the EGR system is operated.

FIG. 5 is a configuration diagram schematically showing a configuration of an engine intake / exhaust system to which the engine exhaust system temperature estimation device according to the first embodiment is applied. FIG. 5 is a block diagram schematically showing a configuration of an engine control device including the engine exhaust system temperature estimation device according to the first embodiment. FIG. 5 is a functional block diagram showing an example of a functional configuration of an engine control device including the engine exhaust system temperature estimation device according to the first embodiment. It is a functional block diagram which shows an example of the structure of the exhaust temperature calculation part at the time of steady combustion in the exhaust system temperature estimation apparatus by Embodiment 1. FIG. FIG. 5 is a functional block diagram showing an example of the configuration of a catalytic reaction heat calculation unit for purifying exhaust gas during steady combustion in the exhaust system temperature estimation device according to the first embodiment. It is explanatory drawing which shows the relationship between the exhaust temperature at the time of steady combustion and the EGR rate. It is explanatory drawing which shows the relationship between the exhaust temperature at the time of steady combustion and the amount of ignition retard. It is a flowchart which shows the operation of the exhaust gas temperature calculation unit at the time of steady combustion in the exhaust system temperature estimation apparatus of the engine by Embodiment 1. It is a flowchart which shows the operation of the catalyst reaction heat calculation unit for exhaust gas purification at the time of steady combustion in the exhaust system temperature estimation apparatus of the engine by Embodiment 1.

Embodiment 1.
FIG. 1 is a configuration diagram schematically showing a configuration of an engine intake / exhaust system to which the engine exhaust system temperature estimation device according to the first embodiment is applied. In FIG. 1, a crank angle sensor 11 for generating an electric signal corresponding to the rotation angle of the crankshaft of the engine 1 is attached. An intake pipe 2 forming an intake passage and an exhaust pipe 7 forming an exhaust passage are connected to the intake port and the exhaust port of the combustion chamber of the engine 1, respectively.

An air cleaner 3 for purifying the taken-in outside air is attached to the most upstream side of the intake pipe 2. On the downstream side (closer to the engine 1) of the air cleaner 3 of the intake pipe 2, an air flow sensor 12 that generates an electric signal according to the intake air flow rate and an electric signal that generates an electric signal according to the intake air temperature in the intake passage are generated. The intake air temperature sensor 13 and the intake air temperature sensor 13 are provided integrally or separately from each other. Note that FIG. 1 shows an example in which the air flow sensor 12 and the intake air temperature sensor 13 are integrally configured.

The exhaust pipe 7 is provided with an exhaust gas purification catalyst 22. An air-fuel ratio sensor 16 that generates an electric signal according to the ratio of fuel or oxygen in the combustion gas is provided on the upstream side (the side close to the engine 1) of the exhaust gas purification catalyst 22 of the exhaust pipe 7.

A throttle valve 4 for adjusting a new amount of air sent to the engine 1 is provided on the downstream side of the air flow sensor 12. A throttle position sensor 14 that generates an electric signal according to the opening degree of the throttle valve is connected to the throttle valve 4.

Further, a surge tank 5 for suppressing intake pulsation is provided on the downstream side of the throttle valve 4 of the intake passage in the intake pipe 2. The surge tank 5 is provided with an intake manifold pressure sensor 15 that generates an electric signal according to the air pressure in the surge tank 5.

Both of the air flow sensor 12 and the intake manifold pressure sensor 15 may be provided, or only the intake manifold pressure sensor 15 may be provided. When only the intake manifold pressure sensor 15 is provided, the intake air temperature sensor 13 is provided in the surge tank 5 as shown in FIG. Further, although FIG. 1 shows an example in which the air flow sensor 12 and the intake manifold pressure sensor 15 are separately configured, these sensors may be integrally configured.

An injector 17 for injecting fuel is provided on the engine 1 side downstream of the surge tank 5 of the intake pipe 2. The injector 17 may be provided so as to inject fuel directly into the cylinder 8 of the engine 1.

At the top of the cylinder 8 of the engine 1, an ignition plug 18 that ignites a flammable air-fuel mixture generated by mixing the air sucked into the engine 1 and the fuel injected from the injector 17, and an ignition spark on the ignition plug 18 Is provided with an ignition coil 19 that supplies energy for generating the above.

Further, at the top of the cylinder 8 of the engine 1, an intake valve 20 for adjusting the amount of combustible air-fuel mixture introduced into the cylinder 8 from the intake pipe 2 forming the intake passage, and the engine 1 from the inside of the cylinder 8 An exhaust valve 21 for adjusting the amount of exhaust gas discharged to the exhaust passage is provided. The intake valve 20 is provided with an intake valve variable timing mechanism (hereinafter, referred to as an intake VVT) 23 that changes the opening / closing timing of the intake valve 20. The exhaust valve 21 is provided with an exhaust valve variable timing mechanism (hereinafter, referred to as an exhaust VVT) 24 that changes the opening / closing timing of the exhaust valve 21.

The electronic control unit (Electronic Control Unit: hereinafter referred to as ECU) 100, which will be described later, detects the phase angle of the intake valve 20 controlled by the intake VVT 23 and the phase angle of the exhaust valve 21 controlled by the exhaust VVT 24, respectively. The phase angle of is controlled so as to match the target phase angle.

The EGR passage 25 is provided so as to connect the exhaust pipe 7 and the intake pipe 2. An EGR valve 26 and an EGR motor 27 for driving the EGR valve are provided in the middle of the EGR passage 25.

FIG. 2 is a block diagram schematically showing the configuration of an engine control device including the engine exhaust system temperature estimation device according to the first embodiment. In FIG. 2, the ECU 100 corresponds to the detection values detected by the crank angle sensor 11, the air flow sensor 12, the intake air temperature sensor 13, the throttle position sensor 14, the intake manifold pressure sensor 15, and the air-fuel ratio sensor 16. Receives an electrical signal.

The ECU 100 also receives electric signals from various sensor OSs other than the above-mentioned sensors. These various sensor OSs include an accelerator position (opening) sensor (not shown) that generates an electric signal according to the amount of operation of the accelerator (not shown), a sensor for combustion control of the engine 1, and vehicle behavior control. Sensors for the purpose (eg, vehicle speed sensor, water temperature sensor, etc.) are included.

In the following description, each electric signal output by each sensor will be described as a detection value detected by each sensor. For example, the electric signal output from the crank angle sensor 11 is expressed as the rotation speed Ne.

The ECU 100 includes a rotation speed Ne from the crank angle sensor 11, an actual measured intake air amount Qr from the air flow sensor 12, an intake air temperature AT from the intake air temperature sensor 13, a throttle opening TH from the throttle position sensor 14, and an intake manifold pressure. Input data of intake manifold pressure Pb from the sensor 15, air-fuel ratio AF from the air-fuel ratio sensor 16, and accelerator opening D from the accelerator opening sensor (OS) that detects the opening of the accelerator provided in the vehicle. Based on the above, the estimated output torque that estimates the actual torque generated from the engine 1 is calculated, the input data from each sensor, and other controller OCOs (for example, transmission control, brake control, traction control, stability control, etc.) The target output torque (not shown) is calculated based on the required torque value TRR from each controller).

Further, in order to achieve the target output torque of the engine 1, the ECU 100 determines the air-fuel ratio AF, the intake air flow rate Qat, the phase angle in the control of the intake VVT 23, the phase angle in the control of the exhaust VVT 24, the EGR rate, the ignition timing, and the like. The throttle valve 4, the injector 17, the ignition coil 19, the intake VVT23, the exhaust VVT24, and the EGR motor 27 are driven so as to achieve the respective target values. More specifically, the throttle valve 4 is controlled so as to achieve the target value of the intake air flow rate Qat, the injector 17 is controlled so as to achieve the target value of the air-fuel ratio AF, and the target value of the ignition timing is achieved. The ignition coil 19 is energized as described above, and the EGR motor 27 is controlled so as to achieve the target value of the EGR rate. In addition, the ECU 100 also calculates target values for various actuator OACs for various devices other than these actuators, and drives various actuator OACs so as to achieve the target values.

Such engine control optimizes the in-cylinder combustion of the engine 1, and after the exhaust gas from this combustion is purified by the exhaust gas purification catalyst 22, it is released to the atmosphere via a muffler (not shown).

Further, the ECU 100 has a function as an exhaust system temperature estimation device that performs an engine exhaust system temperature estimation process, and the functions of the exhaust system temperature estimation device include a function of calculating an exhaust gas temperature estimation value and an exhaust gas. Includes a function to calculate the estimated reaction heat of the catalyst for purification. Then, when at least one of these estimated values is equal to or higher than a predetermined temperature, for example, a temperature at which deterioration of the exhaust gas purification catalyst 22 due to continuous heating is a concern, the amount of fuel is increased. By lowering the temperature of the exhaust gas or prohibiting fuel cut and suppressing the rise in the temperature of the exhaust gas purification catalyst 22, it operates to protect the exhaust system parts such as the exhaust gas purification catalyst 22. To do.

Here, the ECU 100 is composed of a microprocessor having a CPU (Central Processing Unit) 100a for executing arithmetic processing and a storage unit 100b. The storage unit 100b includes a ROM that stores program data and fixed value data, and a RAM that sequentially rewrites and updates the stored data.

FIG. 3 is a functional block diagram showing an example of the functional configuration of the engine control device including the exhaust system temperature estimation device of the engine according to the first embodiment, and FIG. 4A is a functional block diagram of the exhaust system temperature estimation device according to the first embodiment. A functional block diagram showing an example of the configuration of the exhaust gas temperature calculation unit during steady combustion, FIG. 4B is an example of the configuration of the catalytic reaction heat calculation unit for purifying exhaust gas during steady combustion in the exhaust system temperature estimation device according to the first embodiment. It is a functional block diagram which shows. In FIG. 3, the exhaust gas purification catalyst temperature estimation control unit 110 and the fuel control unit 140 are stored as software in the ROM in the storage unit 100b of the ECU 100 described above.

The exhaust gas purification catalyst temperature estimation control unit 110 includes a combustion exhaust gas temperature estimation unit 111, a fuel cut exhaust gas temperature detection unit 112, a combustion exhaust gas purification catalyst reaction heat estimation unit 113, and a fuel cut time. The exhaust gas purification catalyst reaction heat estimation unit 114 and the estimated exhaust gas purification catalyst temperature calculation unit 130 are provided, and these are stored in the ROM in the storage unit 100b of the ECU 100 as software as described above.

The combustion exhaust gas temperature estimation unit 111 includes a steady combustion exhaust gas temperature calculation unit 120, a first smoothing coefficient setting unit 121, and a first smoothing processing unit 122. The catalyst reaction heat estimation unit 113 for purifying exhaust gas during combustion includes a catalyst reaction heat calculation unit 123 for purifying exhaust gas during steady combustion, a second smoothing coefficient setting unit 124, and a second smoothing processing unit 125. I have. The engine 1 includes an injector 17 related to fuel control in the actuator section shown in FIG.

Here, the exhaust gas purification catalyst temperature estimation control unit 110 will be described in detail. As shown in FIG. 4A, the exhaust gas temperature calculation unit 120 during steady combustion in the exhaust gas temperature estimation unit 111 during combustion includes the exhaust gas temperature basic value calculation unit 150 during steady combustion, the ignition retard amount correction means 202, and the EGR amount. The correction means 203 is provided.

In the exhaust gas temperature calculation unit 120 during steady combustion, the exhaust flow rate Qex, the rotation speed Ne of the engine 1, the filling efficiency Ec, the EGR rate, the intake VVT phase angle, the exhaust VVT phase angle, the ignition retard amount, and the like. Based on the above, the exhaust gas temperature during steady combustion is estimated by the first basic data on the exhaust gas temperature during steady combustion, the ignition retard amount correction means 202, and the EGR amount correction means 203, which are prepared in advance in the steady operation state of the engine 1. Calculate the value Tex_map.

More specifically, first, in the exhaust gas temperature basic value calculation unit 150 during steady combustion, the engine is preliminarily based on the rotation speed Ne of the engine 1, the filling efficiency Ec, the intake VVT phase angle, and the exhaust VVT phase angle. The exhaust gas temperature when EGR is not operating (when the EGR rate is 0 [%]) in the steady operation state of 1 is created as the first exhaust gas temperature basic data A during steady combustion for each operating condition of the engine 1. The first exhaust gas temperature basic data A during steady combustion is stored in the first exhaust gas temperature storage means 200 during steady combustion.

Further, in the exhaust gas temperature basic value calculation unit 150 during steady combustion, the steady operation state of the engine 1 is preliminarily based on the rotation speed Ne of the engine 1, the filling efficiency Ec, the intake VVT phase angle, and the exhaust VVT phase angle. The exhaust gas temperature at a predetermined EGR rate (for example, EGR rate 40 [%]) at the time is created as the second exhaust gas temperature basic data N during steady combustion for each operating condition of the engine 1. The second exhaust gas temperature basic data N during steady combustion is stored in the second exhaust gas temperature storage means 201 during steady combustion.

The exhaust gas temperature basic value calculation unit 150 during steady combustion responds to the change in the EGR rate, and the first exhaust gas temperature basic data A during steady combustion is stored in the first exhaust gas temperature storage means 200 during steady combustion. From the value of and the value of the second steady combustion exhaust gas temperature basic data N stored in the second steady combustion exhaust gas temperature storage means 201, the steady combustion exhaust gas corresponding to the current EGR rate. Calculate the basic temperature value Tex_base. At this time, assuming that the air-fuel ratio is the stoichiometric air-fuel ratio and the ignition timing is MBT (Minimum Advance for Best Torque), the reference exhaust gas temperature is calculated. The EGR rate is an ECU calculated value obtained by dividing the flow rate of the exhaust gas passing through the EGR valve 26 by the amount of fresh air intake air.

In the first embodiment, the exhaust gas temperature at one predetermined EGR rate (for example, EGR rate 40 [%]) is set to the exhaust gas temperature at the time of the second steady combustion for each operating condition of the engine 1. Although it is created as basic data N, if the tendency to change of the EGR rate is not linear, it may be set under the condition of a plurality of EGR rates.

FIG. 5A is an explanatory diagram showing the relationship between the exhaust gas temperature during steady combustion and the EGR rate. As shown in FIG. 5A, the tendency of the exhaust gas temperature with respect to the EGR rate during steady operation has a linear characteristic that the exhaust gas temperature decreases as the EGR rate increases. Therefore, without setting a detailed map for each EGR rate, for example, by linearly interpolating and calculating two map values, for example, when EGR is not operating (EGR rate 0 [%]) and EGR rate 40 [%]. , The setting map can be simplified, thereby suppressing the increase in the conforming man-hours.

Next, the ignition retard correction A sets in advance the amount of increase in the exhaust gas temperature corresponding to the amount of ignition retard as a correction value based on the rotation speed Ne of the engine 1 and the filling efficiency Ec, and is based on this correction value. Then, the correction amount is calculated and output by the ignition retard amount correction means 202 according to the ignition retard amount. The EGR correction A sets in advance a decrease in the ignition retard correction amount corresponding to the EGR rate as a correction value based on the filling efficiency Ec, and based on this set value, the EGR amount correction means according to the EGR rate. The correction amount is calculated by 203, the output value from the above-mentioned ignition retard amount correction means 202 is corrected by the calculated correction amount, and the correction value Tex_sarev after correction by EGR correction A by the EGR amount correction means 203 is calculated. And output. The exhaust gas temperature basic value Tex_base during steady combustion from the above-mentioned exhaust gas temperature basic value calculation unit 150 during steady combustion is corrected by the correction value Tex_sarev, and the exhaust gas temperature during steady combustion is estimated from the exhaust gas temperature calculation unit 120 during steady combustion. It is output as the value Tex_map.

FIG. 5B is an explanatory diagram showing the relationship between the exhaust gas temperature during steady combustion and the amount of ignition retard. As shown in FIG. 5B, the tendency of the exhaust gas temperature with respect to the ignition retard amount and the EGR rate is that the larger the ignition retard amount, the higher the exhaust gas temperature, and the higher the EGR rate, the higher the exhaust gas temperature due to the ignition retard. Tends to decrease. By combining the EGR amount correction according to this tendency and the simplification of the data for calculating the above-mentioned basic value Tex_base of the exhaust gas temperature during steady combustion, the estimated exhaust gas temperature at the time of EGR operation can be used as a simple method. Can be estimated more accurately.

Next, returning to FIG. 3, the first smoothing coefficient setting unit 121 in the combustion exhaust gas temperature estimation unit 111 is prepared in advance based on the exhaust gas temperature response delay at the time of transition based on the exhaust flow rate Qex. From the coefficient table, the first smoothing coefficient Film_ex is calculated and output. Here, the exhaust flow rate Qex is an ECU calculated value obtained by adding the intake air amount Qr at the intake process timing corresponding to the current exhaust process timing and the fuel amount calculated from the air-fuel ratio AF.

The first annealing processing unit 122 is calculated by the above-mentioned first annealing coefficient setting unit 121 with respect to the above-mentioned exhaust gas temperature estimated value Tex_map during steady combustion calculated by the above-mentioned exhaust gas temperature calculation unit 120 during steady combustion. Using the first annealing coefficient Filt_ex, for example, an annealing process is performed with a first-order delay, and the estimated exhaust gas temperature Tex_est during steady combustion after the annealing process is calculated and output.

The exhaust gas temperature detection unit 112 at the time of fuel cut estimates the exhaust gas temperature at the time of fuel cut by an exhaust gas temperature estimating means (not shown) and outputs it as an estimated value FC Ex_est of the exhaust gas temperature at the time of fuel cut. The exhaust gas temperature at the time of fuel cut may be detected by the exhaust gas temperature detecting means.

Next, the catalyst reaction heat estimation unit 113 for purifying exhaust gas during combustion shown in FIG. 3 will be described. As shown in FIG. 4B, the catalyst reaction heat calculation unit 123 for purifying exhaust gas during steady combustion in the exhaust gas temperature estimation unit 111 during combustion is the catalyst reaction heat basic value calculation unit 151 for purifying exhaust gas during steady combustion, and the ignition retard. The amount correction means 302 and the EGR amount correction means 303 are provided.

In the catalytic reaction heat calculation unit 123 for purifying exhaust gas during steady combustion, the exhaust flow rate Qex, the rotation speed Ne of the engine 1, the filling efficiency Ec, the EGR rate, the intake VVT phase angle, the exhaust VVT phase angle, and ignition Based on the retard amount and the EGR rate, the first basic data on the catalyst reaction heat for purifying exhaust gas during steady combustion, which was created in advance in the steady operation state of the engine 1, the ignition retard amount correction means 302 and the EGR amount correction means. According to 303, the estimated value Hr_map of the catalyst reaction heat for purifying exhaust gas during steady combustion is calculated.

More specifically, first, in the catalytic reaction heat basic value calculation unit 151 for purifying exhaust gas during steady combustion, the exhaust flow rate Qex, the rotation speed Ne of the engine 1, the filling efficiency Ec, the intake VVT, and the exhaust VVT phase angle Based on the above, the heat of the exhaust gas purification catalyst reaction when the EGR is not operating (when the EGR rate is 0 [%]) in the steady operation state of the engine is preliminarily applied to the first steady combustion for each operating condition of the engine 1. Created as exhaust gas purification catalyst reaction heat basic data A, and this first exhaust gas purification catalyst reaction heat basic data A during steady combustion is used in the first steady combustion exhaust gas purification catalyst reaction heat storage means 300. Remember.

Further, in the catalyst reaction heat basic value calculation unit 151 for purifying exhaust gas during steady combustion, the engine 1 is preliminarily based on the rotation speed Ne of the engine 1, the filling efficiency Ec, the intake VVT phase angle, and the exhaust VVT phase angle. Exhaust gas purification catalyst reaction heat at a predetermined EGR rate (for example, EGR rate 40 [%]) in the steady operation state of the second steady combustion exhaust gas for each operating condition of the engine 1. Created as purification catalyst reaction heat basic data N, and stores the second steady combustion exhaust gas purification catalyst reaction heat basic data N in the second steady combustion exhaust gas purification catalyst reaction heat storage means 301. ..

The basic value calculation unit 151 for the exhaust gas purification catalyst reaction during steady combustion is stored in the first steady-state combustion exhaust gas purification catalyst reaction heat storage means 300 according to the change in the EGR rate. Catalyst reaction heat for purifying exhaust gas during combustion The value of basic data A and the catalyst reaction heat for purifying exhaust gas during steady combustion stored in the second catalyst reaction heat storage means 301 for purifying exhaust gas during steady combustion. From the value of the basic data N, the basic value Hr_base of the catalyst reaction heat for purifying exhaust gas during steady combustion corresponding to the current EGR rate is calculated. At this time, assuming that the air-fuel ratio is the stoichiometric air-fuel ratio and the ignition timing is MBT, the reference heat of the catalyst reaction for exhaust gas purification is calculated. The EGR rate is an ECU calculated value obtained by dividing the flow rate of the exhaust gas passing through the EGR valve 26 by the amount of fresh air intake air.

In the first embodiment, the exhaust gas purification catalytic reaction heat at one predetermined EGR rate (for example, EGR rate 40 [%]) is transferred to the second steady combustion for each operating condition of the engine 1. Although it is created as the catalyst reaction heat basic data N for purifying the exhaust gas, if the tendency for the change in the EGR rate is not linear, it may be set under the condition of a plurality of EGR rates.

Next, in the ignition retard correction B, the amount of increase in the catalyst reaction heat for exhaust gas purification corresponding to the amount of ignition retard is set in advance as a correction value based on the rotation speed Ne of the engine 1 and the filling efficiency Ec. Based on the correction value, the ignition retard amount correction means 302 calculates and outputs the correction amount according to the ignition retard amount. The EGR correction B sets in advance a decrease in the ignition retard correction amount corresponding to the EGR rate as a correction value based on the filling efficiency Ec, and based on this set value, the EGR amount correction means according to the EGR rate. The correction amount is calculated by 303, the output value from the above-mentioned ignition retard amount correction means 302 is corrected by the calculated correction amount, and the correction value Hr_sarev after correction by EGR correction B by the EGR amount correction means 303 is output. ..

The above-mentioned basic value Hr_base of the catalyst reaction heat for purifying exhaust gas during steady combustion from the calculation unit 151 for exhaust gas purification during steady combustion is corrected by the correction value Hr_sarev, and the catalytic reaction for purifying exhaust gas during steady combustion. It is output from the heat calculation unit 123 as an estimated value Hr_map of the catalyst reaction heat for purifying exhaust gas during steady combustion.

Next, returning to FIG. 3, the second smoothing coefficient setting unit 124 in the combustion exhaust gas purification catalyst reaction heat estimation unit 113 previously responds to the exhaust gas purification catalyst reaction heat during transients based on the exhaust flow rate Qex. The second smoothing coefficient Fit_hr is calculated and output from the smoothing coefficient table created based on the delay. Here, the exhaust flow rate Qex is an ECU calculated value obtained by adding the intake air amount Qr at the intake process timing corresponding to the current exhaust process timing and the fuel amount calculated from the air-fuel ratio AF.

The second tanning treatment unit 125 has the above-mentioned second tanning treatment unit 125 with respect to the above-mentioned estimated value Hr_map of the catalyst reaction heat for purifying exhaust gas during steady combustion calculated by the above-mentioned catalyst reaction heat calculation unit 123 for purifying exhaust gas during steady combustion. Using the second smoothing coefficient Fit_hr calculated by the smoothing coefficient setting unit 124, for example, a smoothing process due to a first-order delay is performed, and the estimated catalyst reaction heat Hr_est for purifying exhaust gas during steady combustion after the smoothing process is calculated. Output.

The exhaust gas purification catalyst reaction heat estimation unit 114 at the time of fuel cut estimates the exhaust gas purification catalyst reaction heat at the time of fuel cut, calculates and outputs the estimated value FCHr_est of the exhaust gas purification catalyst reaction heat at the time of fuel cut.

The catalyst temperature calculation unit 130 for estimating exhaust gas purification is the exhaust gas temperature estimation value Tex_est during steady combustion calculated by the exhaust gas temperature estimation unit 111 during combustion, or the exhaust gas during fuel cut calculated by the exhaust gas temperature detection unit 112 during fuel cut. The gas temperature estimation value FCEx_est includes the catalyst reaction heat estimation value Hr_est for steady combustion exhaust gas purification calculated by the catalyst reaction heat estimation unit 113 for exhaust gas purification during combustion, and the catalyst reaction heat estimation unit 114 for exhaust gas purification during fuel cut. The estimated value FCHr_est of the catalyst reaction heat for exhaust gas purification at the time of fuel cut calculated in the above is added, and the estimated value Tcat_est of the catalyst temperature for exhaust gas purification is calculated.

When the exhaust gas purification catalyst temperature estimated value Tcat_est is equal to or higher than a predetermined temperature, for example, a temperature at which deterioration of the exhaust gas purification catalyst 22 due to continuous heating is a concern, the fuel control unit 140 is used for exhaust gas purification. Fuel increase control or fuel cut prohibition control for protection of the catalyst 22 is implemented.

Subsequently, the calculation operation of the exhaust gas temperature estimated value Tex_map during steady combustion and the catalyst reaction heat estimated value Hr_map for purifying exhaust gas during steady combustion according to the first embodiment will be described with reference to the flowchart. FIG. 6A is a flowchart showing the operation of the exhaust gas temperature calculation unit during steady combustion in the exhaust system temperature estimation device of the engine according to the first embodiment, and shows an example of calculation of the exhaust gas temperature estimation value Tex_map during steady combustion. It shows the operation. FIG. 6B is a flowchart showing the operation of the catalytic reaction heat calculation unit for purifying exhaust gas during steady combustion in the engine exhaust system temperature estimation device according to the first embodiment, and estimates the catalytic reaction heat for purifying exhaust gas during steady combustion. The operation which shows an example of the operation of the value Hr_map is shown.

In FIG. 6A, in step S101, the first steady combustion created in advance in the steady state when the EGR is not activated based on the rotation speed Ne of the engine 1, the filling efficiency Ec, the phase angle of the intake VVT, and the phase angle of the exhaust VVT. The MAP value A is calculated from the hourly exhaust gas temperature basic data A, and the process proceeds to step S102.

In step S102, the exhaust gas temperature during the second steady combustion, which is prepared in advance in the steady state at the time of EGR operation, based on the rotation speed Ne of the engine 1, the filling efficiency Ec, the phase angle of the intake VVT, and the phase angle of the exhaust VVT. The MAP value B is calculated from the data N, and the process proceeds to step S103.

In step S103, a value corresponding to the current EGR rate is interpolated from the MAP value A calculated in step S101 and the MAP value B calculated in step S102, and the exhaust gas temperature basic value Tex_base during steady combustion is calculated. The process proceeds to step S104.

In step S104, the MAP is set according to the current ignition retard amount from the ignition retard correction A map in which the exhaust temperature rise corresponding to the ignition retard amount is set as the correction value in advance based on the rotation speed Ne and the filling efficiency Ec of the engine 1. The value C is calculated, and the process proceeds to step S105.

In step S105, the MAP value D is calculated according to the current EGR rate from the EGR correction A map in which the decrease in the ignition retard correction amount corresponding to the EGR rate is set as the correction value in advance based on the filling efficiency Ec. The process proceeds to step S106.

In step S106, the MAP value C calculated in step S104 is corrected by the MAP value D calculated in step S105, the correction value Tex_sarev is calculated, and the process proceeds to step S107.

In step S107, the basic value Tex_base of the exhaust gas temperature during steady combustion calculated in step S103 is corrected by the correction value Tex_sarev calculated in step S106, the estimated value Tex_map of the exhaust gas temperature during steady combustion is calculated, and the process is exited.

Next, in FIG. 6B, in step S108, based on the exhaust flow rate Qex, the rotation speed Ne of the engine 1, the filling efficiency Ec, the phase angle of the intake VVT, and the phase angle of the exhaust VVT, in a steady state when the EGR is not activated in advance. The MAP value E is calculated from the created first basic data A of the catalyst reaction heat for purifying exhaust gas during steady combustion, and the process proceeds to step S109.

In step S109, for purifying the exhaust gas during the second steady combustion, which is prepared in advance in the steady state at the time of EGR operation based on the exhaust flow rate Qex, the rotation speed Ne of the engine 1, the filling efficiency Ec, the intake VVT and the exhaust VVT phase angle. The MAP value F is calculated from the catalyst reaction heat basic data N, and the process proceeds to step S110.

In step S110, a value corresponding to the current EGR rate is interpolated from the MAP value E calculated in step S108 and the MAP value F calculated in step S109, and the catalyst reaction heat basic value Hr_base for purifying exhaust gas during steady combustion is calculated. Calculate and proceed to step S111.

In step S111, the current ignition is generated from the ignition retard correction B map in which the amount of increase in the catalyst reaction heat for exhaust gas purification corresponding to the ignition retard amount is set as a correction value in advance based on the rotation speed Ne and the filling efficiency Ec of the engine 1. The MAP value G is calculated according to the retard amount, and the process proceeds to step S112.

In step S112, the MAP value H is calculated according to the current EGR rate from the EGR correction B map in which the decrease in the ignition retard correction amount corresponding to the EGR rate is set as the correction value in advance based on the filling efficiency Ec. The process proceeds to step S113.

In step S113, the MAP value G calculated in step S111 is corrected by the MAP value H calculated in step S112, the correction value Hr_sarev is calculated, and the process proceeds to step S114.

In step S114, the basic value Hr_base of the catalyst reaction heat for purifying exhaust gas during steady combustion calculated in step S110 is corrected by the correction value Hr_sarev calculated in step S113, and the estimated value Hr_map of the catalyst reaction heat for purifying exhaust gas during steady combustion is calculated. And exit the process.

According to the engine exhaust system temperature estimation device according to the first embodiment described above, the basic data of the exhaust gas temperature during steady combustion set based on the engine operating state and the basics of the catalyst reaction heat for purifying the exhaust gas during steady combustion. It is possible to suppress an increase in the amount of set data and an increase in the number of matching steps without setting a large amount of data due to the difference in EGR rate conditions.

In addition, by using a means for correcting the amount of ignition retard correction according to the EGR rate, the exhaust temperature during EGR operation and the exhaust gas purification catalyst temperature can be estimated accurately while using a simple method. Can be done.

Although the present application describes various exemplary embodiments and examples, the various features, embodiments, and functions described in one or more embodiments are applications of a particular embodiment. It is not limited to, but can be applied to embodiments alone or in various combinations. Therefore, innumerable variations not illustrated are envisioned within the scope of the techniques disclosed in the present application. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1 engine, 2 intake pipe, 3 air cleaner, 4 throttle valve, 5 surge tank, 7 exhaust pipe, 8 cylinder, 11 crank angle sensor, 12 air flow sensor, 13 intake temperature sensor, 14 throttle position sensor, 15 intake manifold pressure sensor, 16 Air-fuel ratio sensor, 17 injector, 18 ignition plug, 19 ignition coil, 20 intake valve, 21 exhaust valve, 22 exhaust gas purification catalyst, 23 intake VVT, 24 exhaust VVT, 25 EGR passage, 26 EGR valve, 27 EGR motor , 100 ECU, 100a CPU, 100b storage unit, 110 Exhaust gas purification catalyst temperature estimation control unit, 111 Exhaust gas temperature estimation unit during combustion, 112 Exhaust gas temperature detection unit during fuel cut, 113 Catalytic reaction for exhaust gas purification during combustion Heat estimation unit, 114 Exhaust gas purification catalyst reaction heat estimation unit during fuel cut, 120 Exhaust gas temperature calculation unit during steady combustion, 121 First smoothing coefficient setting unit, 122 First smoothing processing unit, 123 Constant combustion Exhaust gas purification catalyst reaction heat calculation unit, 124 2nd smoothing coefficient setting unit, 125 2nd smoothing processing unit, 130 Estimated exhaust gas purification catalyst temperature calculation unit, 140 Fuel control unit, 150 During steady combustion Exhaust gas temperature basic value calculation unit, 151 Exhaust gas purification catalyst reaction heat basic value calculation unit during steady combustion, 200 1st exhaust gas temperature storage means during steady combustion, 201 2nd exhaust gas temperature storage means during steady combustion, 202 Ignition retard correction means, 203 EGR amount correction means, 300 First constant combustion exhaust gas purification catalytic reaction heat storage means, 301 Second steady combustion exhaust gas purification catalytic reaction heat storage means, 302 Ignition retard Amount correction means, 303 EGR amount correction means

Claims (2)

An engine exhaust system that estimates the temperature of the engine exhaust system in an engine equipped with an EGR system that returns the exhaust gas discharged from the engine to the engine and an exhaust gas purification catalyst that purifies the exhaust gas of the engine. It is a temperature estimation device
An engine operating state detecting means for detecting an operating state of the engine including at least the rotational speed of the engine and the load of the engine.
An EGR rate detecting means for detecting an EGR rate controlled by the EGR system,
A first type that stores the temperature of the exhaust gas when the EGR system is not operating in the steady operation state of the engine as the first exhaust gas temperature basic data during steady combustion for each operating condition of the engine. Exhaust gas temperature storage means during steady combustion,
The temperature of the exhaust gas of the engine when the EGR system is operated at a predetermined EGR rate in the steady operation state of the engine is set to the exhaust during the second steady combustion for each operating condition of the engine. The second exhaust gas temperature storage means for steady combustion, which is stored as basic gas temperature data,
According to the change in the EGR rate, the first steady combustion exhaust gas temperature basic data stored in the first steady combustion exhaust gas temperature storage means and the second steady combustion exhaust gas temperature storage. Calculation of the basic value of the exhaust gas temperature during steady combustion corresponding to the current EGR rate based on the second basic data of the exhaust gas temperature during steady combustion stored in the means. Department and
An ignition retard amount correcting means that corrects the exhaust gas temperature basic value during steady combustion calculated by the exhaust gas temperature basic value calculation unit during steady combustion according to the ignition retard amount of the engine.
An EGR amount correction means that corrects the correction amount for correcting the exhaust gas temperature basic value during steady combustion by the ignition retard amount correction means according to the EGR rate.
The first averaging coefficient which is calculated based on the exhaust gas temperature response delay of the engine, before Symbol ignition retard quantity correction means and the EGR amount correction means and the corrected the steady combustion at the exhaust gas temperature basic value on the basis of the The combustion exhaust gas temperature estimation unit that outputs the estimated value of the exhaust gas temperature during steady combustion obtained by performing the first annealing treatment on the vehicle, and
With
It is configured to estimate the temperature of the exhaust system based on the estimated value of the exhaust gas temperature during steady combustion output from the exhaust gas temperature estimation unit during combustion.
An engine exhaust system temperature estimator characterized by this. An engine exhaust system that estimates the temperature of the engine exhaust system in an engine equipped with an EGR system that returns the exhaust gas discharged from the engine to the engine and an exhaust gas purification catalyst that purifies the exhaust gas of the engine. It is a temperature estimation device
An engine operating state detecting means for detecting an operating state of the engine including at least the rotational speed of the engine and the load of the engine.
An exhaust gas temperature detecting means for detecting the temperature of the exhaust gas of the engine flowing into the exhaust gas purifying catalyst, or an exhaust gas temperature estimating means for estimating the temperature of the exhaust gas based on the operating state of the engine.
An EGR rate detecting means for detecting an EGR rate controlled by the EGR system,
Exhaust gas purification catalyst reaction heat when the engine is in a steady operation state and when the EGR system is not operating, and the first exhaust gas purification catalyst reaction heat basic data for each operating condition of the engine. The first catalyst reaction heat storage means for purifying exhaust gas during steady combustion, which is stored as
The reaction heat of the exhaust gas purification catalyst when the engine is operated at a predetermined EGR rate in the steady operation state of the engine is subjected to a second steady combustion for each operating condition of the engine. The second catalyst reaction heat storage means for purifying exhaust gas during steady combustion, which is stored as basic data, and the catalyst reaction heat storage means for purifying exhaust gas.
Based on the first basic data on the catalyst reaction heat for purifying exhaust gas during steady combustion and the second basic data on the catalyst reaction heat for purifying exhaust gas during steady combustion, according to the change in the EGR rate. Calculates the basic value of the catalyst reaction heat for purifying exhaust gas during steady combustion corresponding to the EGR rate.
Ignition retard amount correction means that corrects the catalyst reaction heat basic value for exhaust gas purification during steady combustion calculated by the calculation unit for the exhaust gas purification catalyst reaction heat during steady combustion according to the ignition retard amount of the engine. When,
The EGR amount correction means for correcting the correction amount for correcting the basic value of the catalyst reaction heat for purifying exhaust gas during steady combustion by the ignition retard amount correction means according to the EGR rate.
The exhaust gas during steady combustion is corrected based on the ignition retard amount correction means and the EGR amount correction means by the second smoothing coefficient calculated based on the catalyst reaction thermal response delay for purifying the exhaust gas of the engine. The catalyst reaction heat estimation unit for combustion exhaust gas purification that outputs the estimated value of the exhaust gas purification catalyst reaction heat during steady combustion obtained by performing the second tanning treatment on the basic value of the catalyst reaction heat for purification,
With
It is configured to estimate the temperature of the exhaust system based on the estimated value of the catalyst reaction heat for purifying exhaust gas during steady combustion output from the catalyst reaction heat estimation unit for purifying exhaust gas during combustion.
An engine exhaust system temperature estimator characterized by this.

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