JP4830870B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that performs post-injection in an exhaust stroke of the internal combustion engine to regenerate the aftertreatment device.

  In recent years, a system for collecting particulates discharged from a diesel engine (hereinafter referred to as an internal combustion engine) with a diesel particulate filter (hereinafter referred to as a collector) has been developed. In order to use this continuously, it is necessary to recycle the collector by periodically burning and removing the particulates accumulated in the collector. The temperature is raised to a temperature at which the particulates burn, and the accumulated particulates are removed by combustion. Incidentally, as a method of raising the collector temperature, there is known a method in which post-injection is performed after main injection to supply unburned HC to the collector, and the temperature inside the collector is raised by an oxidation reaction of unburned HC. It has been.

  However, if the exhaust gas temperature or collector temperature becomes too high during regeneration of the collector, the collector or engine components exposed to the high temperature (for example, EGR system parts including EGR coolers and EGR valves, superchargers) ) May be thermally damaged. For this reason, a temperature control method has been proposed in which the collector can be regenerated without receiving thermal damage to the collector or engine parts.

  For example, there is one that adjusts the operation amount of the temperature raising means for raising the collector temperature according to the collector temperature to prevent thermal damage to the collector (see, for example, Patent Document 1).

In addition, an exhaust gas temperature upper limit is set for the exhaust gas temperature detected by the exhaust temperature sensor so that thermal damage to the engine parts does not occur. There is one that prevents thermal damage (see, for example, Patent Document 2).
JP-A-2005-240672 Japanese Patent Laid-Open No. 2004-21680

  However, the device proposed in Patent Document 1 prevents only thermal damage of the collector, and cannot detect a high temperature of the engine component, thereby preventing thermal damage of the engine component. I can't.

  Further, the apparatus proposed in Patent Document 2 changes the injection timing and the injection amount to lower the exhaust gas temperature, so that the collector temperature also decreases. For example, the collector temperature is too low and the particulates There is a risk of adverse effects on the regeneration of the collector, such as being not removed by combustion.

  In view of the above points, the present invention provides a control device for an internal combustion engine that performs post-injection to regenerate the aftertreatment device, and suppresses the temperature change of the aftertreatment device during regeneration of the aftertreatment device, while also causing thermal damage to engine parts. The purpose is to make it possible to avoid this.

  In the first feature of the present invention, a turbocharger (13) for controlling a flow rate when exhaust gas flows into the turbine (14) by a nozzle (16), and post-processing for treating harmful substances in the exhaust gas. A control device for an internal combustion engine mounted on an internal combustion engine (1) having a device (40) and performing post-injection to regenerate the post-processing device (40), the exhaust upstream of the turbine (14) When the value of the turbine upstream gas temperature, which is the gas temperature, exceeds a predetermined value, the flow rate of the exhaust gas flowing into the turbine (14) is lower than when the value of the turbine upstream gas temperature is less than the predetermined value. Turbine upstream gas temperature lowering means (S102) for controlling the operation of the nozzle (16) is provided.

  In such a configuration, by reducing the flow rate of the exhaust gas flowing into the turbine (14), the exhaust pressure upstream of the turbine is lowered, and consequently the temperature of the exhaust gas upstream of the turbine is lowered. Thermal damage can be avoided. Moreover, since the temperature of exhaust gas can be reduced without changing the injection quantity of post injection, the temperature change of a post-processing apparatus (40) can be suppressed.

  In this case, an exhaust gas temperature sensor (72) for detecting the temperature of the turbine downstream gas, which is the temperature of the exhaust gas between the turbine (14) and the aftertreatment device (40), is provided and detected by this exhaust gas temperature sensor (72) The turbine upstream gas temperature can be estimated based on the turbine downstream gas temperature.

  In this way, since the information of the exhaust temperature sensor (72) originally used for temperature control of the aftertreatment device (40) is used, it is possible to estimate the turbine upstream gas temperature without providing a new exhaust temperature sensor. it can.

  Also, information on the turbine downstream gas temperature, which is the temperature of the exhaust gas between the turbine (14) and the aftertreatment device (40), and the turbine front-rear temperature difference, which is the difference between the turbine upstream gas temperature and the turbine downstream gas temperature. Information can be acquired, and the turbine upstream gas temperature can be estimated by adding the temperature difference before and after the turbine to the turbine downstream gas temperature. Since the temperature difference between the front and rear of the turbine changes according to the turbine downstream gas temperature and the nozzle operating position, the turbine front and rear temperature difference is estimated based on at least one of the turbine downstream gas temperature and the nozzle (16) operating position. Thus, the turbine upstream gas temperature can be estimated more accurately.

  Further, since the temperature difference between the front and rear of the turbine changes according to the opening and intake pressure of the intake throttle valve (22), if the temperature difference between the front and rear of the turbine is estimated based on the opening and intake pressure of the intake throttle valve (22). The turbine upstream gas temperature can be estimated more accurately.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a diagram showing an overall configuration of a control device for an internal combustion engine according to a first embodiment of the present invention.

  An internal combustion engine 1 shown in FIG. 1 is a water-cooled diesel engine mounted on a vehicle, and the vehicle is driven by the internal combustion engine 1. The internal combustion engine 1 includes a common rail 11 that stores high-pressure fuel, and a plurality of fuel injection valves 12 that are connected to the common rail 11 and inject fuel into a cylinder of the internal combustion engine 1. Incidentally, the pressure of the fuel is increased by a pump (not shown) driven by the internal combustion engine 1, and the high-pressure fuel is pumped to the common rail 11.

  An intake pipe 20 is connected to an intake manifold 21 of the internal combustion engine 1, and an intake throttle valve 22 is provided at the connection portion. The intake throttle valve 22 adjusts the passage area of the intake system to adjust the intake flow rate.

  An exhaust pipe 30 is connected to the exhaust manifold 31 of the internal combustion engine 1, and is collected in the middle of the exhaust pipe 30 as a post-processing device that collects particulates (hereinafter referred to as PM) in the exhaust gas. A container 40 is arranged.

  For example, the collector 40 is formed by forming heat-resistant ceramics such as cordierite into a honeycomb structure, and alternately sealing the inlets or outlets of a large number of exhaust passages 401 partitioned by porous partition walls. Become. The exhaust gas from the internal combustion engine 1 enters the exhaust passage 401 having an opening on the inlet side, passes through the porous partition wall, and flows into the adjacent exhaust passage 401. PM is collected when passing through the partition walls. Further, an oxidation catalyst 41 is disposed on the exhaust pipe 30 upstream of the collector 40.

  A turbine 14 of a turbocharger 13 that pressurizes intake air is provided upstream of the oxidation catalyst 41 in the exhaust pipe 30. The turbine 14 is connected to a compressor 15 provided in the intake pipe 20 and a turbine shaft. It is connected. Thus, the turbine 14 is driven using the thermal energy of the exhaust gas, and the compressor 15 is driven via the turbine shaft, and the intake air introduced into the intake pipe 20 is compressed in the compressor 15.

  FIG. 2 schematically shows the configuration of the turbine 14. A plurality of nozzles 16 provided on the outer periphery of the turbine 14 are driven by a driving means such as an electric motor (not shown). The flow rate of the exhaust gas flowing into the turbine 14 can be changed by changing the inclination of the nozzle 16. Incidentally, as the inclination of the nozzle 16 becomes closer to the solid line position from the broken line position in FIG. 2, the flow rate of the exhaust gas flowing into the turbine 14 increases.

  As shown in FIG. 1, an intercooler 23 is provided in the intake pipe 20 downstream of the compressor 15 and upstream of the intake throttle valve 22 for cooling the intake air that has been compressed by the compressor 15 and has reached a high temperature. It has been.

  The exhaust manifold 31 is connected to the intake manifold 21 by a high-pressure EGR passage 50 so that a part of the exhaust gas is returned to the intake system through the high-pressure EGR passage 50. More specifically, the high-pressure EGR passage 50 branches from the upstream side of the turbine 14 in the exhaust system and is connected downstream of the intake throttle valve 22 in the intake system.

  The high pressure EGR passage 50 is provided with a high pressure EGR valve 51, and the passage area of the high pressure EGR passage 50 is adjusted by the high pressure EGR valve 51 so that the amount of exhaust gas recirculated to the intake system is adjusted. A high-pressure EGR cooler 52 for cooling the exhaust gas to be refluxed is provided on the high-pressure EGR passage 50 upstream of the high-pressure EGR valve 51.

  Further, the exhaust pipe 30 is connected to the intake pipe 20 by a low-pressure EGR passage 60, and a part of the exhaust gas is returned to the intake system through the low-pressure EGR passage 60. More specifically, the low pressure EGR passage 60 branches from the downstream side of the collector 40 in the exhaust system and is connected upstream of the compressor 15 in the intake system.

  The low pressure EGR passage 60 is provided with a low pressure EGR valve 61, and the passage area of the low pressure EGR passage 60 is adjusted by the low pressure EGR valve 61 so that the amount of exhaust gas recirculated to the intake system is adjusted. In addition, a low pressure EGR cooler 62 for cooling the exhaust gas to be recirculated is provided upstream of the low pressure EGR valve 61 in the low pressure EGR passage 60.

  The exhaust manifold 31 is provided with an exhaust pressure sensor 71 that outputs an electrical signal corresponding to the exhaust pressure upstream of the turbine 14. Between the turbine 14 and the oxidation catalyst 41 in the exhaust pipe 30, a first exhaust temperature sensor 72 that outputs an electric signal corresponding to the temperature of the exhaust gas that passes through the turbine 14 and flows into the oxidation catalyst 41 is provided. Yes.

  A second exhaust temperature sensor 73 that outputs an electrical signal corresponding to the temperature of the exhaust gas that has passed through the collector 40 is provided on the exhaust pipe 30 downstream of the collector 40. The intake pipe 20 upstream of the compressor 15 is provided with an air flow meter 74 that outputs an electric signal corresponding to the intake flow rate. The intake manifold 21 is provided with an intake pressure sensor 75 that outputs an electrical signal corresponding to the intake pressure downstream of the intake throttle valve 22. The internal combustion engine 1 is provided with a rotation speed sensor 76 that detects the rotation speed of the internal combustion engine.

  The ECU 80 includes a known microcomputer including a CPU, a ROM, an EEPROM, a RAM, and the like (not shown), and performs arithmetic processing according to a program stored in the microcomputer. The ECU 80 receives signals from the sensors 71 to 76, and further opens the opening of the intake throttle valve 22, the opening of the high pressure EGR valve 51, the opening of the low pressure EGR valve 61, the vehicle speed, the accelerator opening, Signals from various sensors (not shown) for detecting the coolant temperature, the crank position, the fuel pressure, and the like are input. Further, the ECU 80 controls the fuel injection valve 12, the nozzle 16, the intake throttle valve 22, the high pressure EGR valve 51, the low pressure EGR valve 61, and the like based on the calculation result.

  Next, the operation of this embodiment will be described. In the present embodiment, the PM accumulation amount of the collector 40 is estimated by a known method, and when the PM accumulation amount reaches a predetermined value, the collector 40 is regenerated. Specifically, the ECU 80 controls the operation of the fuel injection valve 12 so that post injection is performed after main injection in the exhaust stroke of the internal combustion engine 1. By this post injection, unburned HC is supplied to the collector 40, the collector 40 is heated by an oxidation reaction of unburned HC, and PM deposited on the collector 40 is burned and removed. .

  Next, control for avoiding thermal damage to the turbine 14 will be described. FIG. 3 is a flowchart showing a damage avoidance control process executed by the ECU 80. This process is started when the key switch is operated to the on position in order to operate the internal combustion engine 1, and the internal combustion engine 1 is stopped. Therefore, the operation is terminated when the key switch is operated to the off position.

  As shown in FIG. 3, first, in step S <b> 100 as the turbine upstream gas temperature acquisition means, the turbine upstream gas temperature that is the temperature of the exhaust gas upstream of the turbine 14 is estimated. Here, FIG. 4 is a characteristic diagram showing the relationship between the turbine downstream gas temperature, which is the temperature of the exhaust gas downstream from the turbine 14, and the turbine upstream gas temperature. As the turbine downstream gas temperature increases, FIG. Therefore, the turbine upstream gas temperature is also increased. Therefore, in the present embodiment, the turbine upstream gas temperature is estimated based on the turbine downstream gas temperature detected by the first exhaust temperature sensor 72.

  A map defining the relationship between the turbine downstream gas temperature and the turbine upstream gas temperature shown in FIG. 4 is stored in the ROM of the ECU 80, and the turbine upstream gas temperature can be obtained from the map.

  In the next step S101, the turbine upstream gas temperature estimated in step S100 is compared with a predetermined value T1, and if the turbine upstream gas temperature is equal to or lower than the predetermined value T1 (NO in step S101), the damage avoidance control process is temporarily ended. .

  On the other hand, when the turbine upstream gas temperature estimated in step S100 exceeds the predetermined value T1 (YES in step S101), in other words, when the turbine 14 may be thermally damaged, the process proceeds to step S102.

  In step S102 as the turbine upstream gas temperature lowering means, control for lowering the turbine upstream gas temperature is performed. In the present embodiment, the flow rate of the exhaust gas flowing into the turbine 14 is changed by changing the inclination of the nozzle 16. Specifically, the flow rate of the exhaust gas flowing into the turbine 14 when the turbine upstream gas temperature exceeds a predetermined value T1, and the flow rate of the exhaust gas flowing into the turbine 14 when the turbine upstream gas temperature is equal to or lower than the predetermined value T1. The operation of the nozzle 16 is controlled to be lower.

  More specifically, a map that defines the target opening degree of the nozzle 16 with respect to the internal combustion engine speed and the accelerator opening degree (applicable value when the turbine upstream gas temperature is equal to or lower than the predetermined value T1) is stored in the ROM of the ECU 80, When the turbine upstream gas temperature is equal to or lower than the predetermined value T1, the target opening is obtained from the map based on the engine speed and the accelerator opening, and the operation of the nozzle 16 is controlled so as to be the target opening. On the other hand, when the turbine upstream gas temperature exceeds the predetermined value T1, the target opening is obtained from the map based on the engine speed and the accelerator opening, and the flow rate of the exhaust gas flowing into the turbine 14 is reduced. The target opening is corrected, and the operation of the nozzle 16 is controlled so that the corrected target opening is obtained.

  Here, FIG. 5 is a characteristic diagram showing the relationship between the flow velocity of the exhaust gas flowing into the turbine 14 and the turbine upstream gas temperature when the temperature of the collector 40 is constant. As shown in FIG. 5, by reducing the flow rate of the exhaust gas flowing into the turbine 14, the exhaust pressure upstream of the turbine is reduced and the turbine upstream gas temperature is lowered.

  And the process of step S100-102 is repeatedly performed until turbine upstream gas temperature becomes below predetermined value T1 (step S101 is NO), and the thermal damage of the turbine 14 is avoided. Moreover, since the turbine upstream gas temperature can be lowered without changing the injection amount of the post injection, the temperature change of the collector 40 is suppressed even if step S102 is executed during the regeneration of the collector 40. Can do.

  As described above, according to the present embodiment, thermal damage to the turbine 14 can be avoided while suppressing the temperature change of the collector 40.

  Further, since the turbine upstream gas temperature is estimated based on the turbine downstream gas temperature detected by the first exhaust temperature sensor 72, the turbine upstream gas temperature can be estimated without providing a new exhaust temperature sensor.

  In addition, you may obtain | require turbine upstream gas temperature as follows ac.

  (A) The vertical axis | shaft of FIG. 6 is a turbine back-and-front temperature difference which is a difference of turbine upstream gas temperature and turbine downstream gas temperature, and a horizontal axis is turbine downstream gas temperature. Since the amount of heat release increases as the turbine downstream gas temperature increases, as shown in FIG. 6, the temperature difference between the front and rear of the turbine increases as the turbine downstream gas temperature increases.

  Accordingly, in step S100, the temperature difference between the turbine front and rear is estimated based on the turbine downstream gas temperature detected by the first exhaust temperature sensor 72, and the estimated turbine front and rear temperature difference is added to the turbine downstream gas temperature to obtain the turbine upstream gas temperature. Is estimated.

  Since the temperature difference between the front and rear of the turbine changes according to the turbine downstream gas temperature, the turbine upstream gas temperature can be estimated more accurately in this way.

  (B) The vertical axis in FIG. 7 is the temperature difference across the turbine, and the horizontal axis is the flow rate of the exhaust gas flowing into the turbine 14. As the flow rate of the exhaust gas flowing into the turbine 14 increases and the supercharging amount increases, the work amount of the turbocharger 13 increases, so that the flow rate of the exhaust gas flowing into the turbine 14 increases as shown in FIG. As the temperature increases, the temperature difference between the front and rear of the turbine increases.

  Therefore, in step S100, the temperature difference between the front and rear of the turbine is estimated based on the operating position of the nozzle 16 that correlates with the flow rate of the exhaust gas flowing into the turbine 14, and the estimated temperature difference before and after the turbine is added to the turbine downstream gas temperature. To estimate the turbine upstream gas temperature.

  Since the temperature difference between the front and rear of the turbine changes according to the nozzle operating position, the turbine upstream gas temperature can be estimated more accurately in this way.

  (C) FIG. 8 is a map of the temperature difference across the turbine with respect to the opening of the intake throttle valve 22 and the intake pressure downstream of the intake throttle valve 22. At the same opening degree of the intake throttle valve 22, the higher the intake pressure, the more the turbocharger 13 is working and the greater the temperature difference between the front and rear of the turbine. Further, at the same intake pressure, the turbocharger 13 is doing more work as the opening of the intake throttle valve 22 is smaller, and the temperature difference between the front and rear of the turbine becomes larger. Therefore, the map of FIG. 8 shows that the opening and closing of the intake throttle valve 22 and the intake pressure are increased so that the difference in temperature before and after the turbine increases as the opening of the intake throttle valve 22 decreases and the intake pressure increases. A temperature difference relationship is defined.

  Therefore, in step S100, the turbine front-rear temperature difference is obtained from the map of FIG. 8 based on the opening of the intake throttle valve 22 and the intake pressure detected by the intake pressure sensor 75, and the obtained turbine front-rear temperature difference is determined downstream of the turbine. The turbine upstream gas temperature is estimated by adding to the gas temperature.

  Since the temperature difference between the front and rear of the turbine changes according to the opening of the intake throttle valve 22 and the intake pressure, the turbine upstream gas temperature can be estimated more accurately in this way.

(Second Embodiment)
A second embodiment of the present invention will be described. In the first embodiment, thermal damage to the turbine 14 can be avoided while suppressing the temperature change of the collector 40, whereas in the present embodiment, the high pressure EGR is suppressed while suppressing the temperature change of the collector 40. This makes it possible to avoid thermal damage to system parts.

  In addition, since the whole structure of the control apparatus for internal combustion engines of this embodiment is the same as the whole structure of the control apparatus for internal combustion engines of 1st Embodiment, this embodiment is demonstrated below, referring FIG.

  FIG. 9 is a flowchart showing a damage avoidance control process executed by the ECU 80 in the control device of the present embodiment. This process starts when the key switch is operated to the ON position in order to operate the internal combustion engine 1. When the key switch is operated to the off position in order to stop the internal combustion engine 1, the process is terminated.

  As shown in FIG. 9, first, in step S200 as the high pressure EGR gas temperature acquisition means, the high pressure EGR gas temperature that is the temperature of the exhaust gas in the high pressure EGR passage 50 is estimated. More specifically, the temperature of the exhaust gas between the high pressure EGR valve 51 and the high pressure EGR cooler 52 is estimated.

  Here, FIG. 10 is a characteristic diagram showing the relationship between the turbine downstream gas temperature and the high-pressure EGR gas temperature. As described above, as the turbine downstream gas temperature increases, the turbine upstream gas temperature also increases (see FIG. 4). As the turbine upstream gas temperature increases, the high-pressure EGR gas temperature also increases. Therefore, as shown in FIG. 10, as the turbine downstream gas temperature increases, the high-pressure EGR gas temperature also increases. Therefore, in the present embodiment, the high-pressure EGR gas temperature is estimated based on the turbine downstream gas temperature detected by the first exhaust temperature sensor 72. A map defining the relationship between the turbine downstream gas temperature and the high pressure EGR gas temperature shown in FIG. 10 is stored in the ROM of the ECU 80, and the high pressure EGR gas temperature can be obtained from the map.

  In the next step S201, the high pressure EGR gas temperature estimated in step S200 is compared with a predetermined value T2, and if the high pressure EGR gas temperature is equal to or lower than the predetermined value T2 (step S201 is NO), the damage avoidance control process is temporarily ended. .

  On the other hand, when the high pressure EGR gas temperature estimated in step S200 exceeds the predetermined value T2 (step S201 is YES), in other words, the high pressure EGR valve 51 and the high pressure EGR cooler 52 may be thermally damaged. Sometimes, the process proceeds to step S202.

  In step S202 as the high pressure EGR gas temperature lowering means, control for lowering the high pressure EGR gas temperature is performed. In the present embodiment, the flow rate of the exhaust gas flowing into the turbine 14 is changed by changing the inclination of the nozzle 16. Specifically, the flow rate of the exhaust gas flowing into the turbine 14 when the high-pressure EGR gas temperature exceeds a predetermined value T2, and the flow rate of the exhaust gas flowing into the turbine 14 when the high-pressure EGR gas temperature is equal to or lower than the predetermined value T2. The operation of the nozzle 16 is controlled to be lower.

  More specifically, a map that defines the target opening degree of the nozzle 16 with respect to the internal combustion engine speed and the accelerator opening degree (applicable value when the high-pressure EGR gas temperature is equal to or lower than the predetermined value T2) is stored in the ROM of the ECU 80. When the high-pressure EGR gas temperature is equal to or lower than the predetermined value T2, the target opening is obtained from the map based on the engine speed and the accelerator opening, and the operation of the nozzle 16 is controlled so as to be the target opening. On the other hand, when the high-pressure EGR gas temperature exceeds the predetermined value T2, the target opening is obtained from the map based on the engine speed and the accelerator opening, and the flow rate of the exhaust gas flowing into the turbine 14 is reduced. The target opening is corrected, and the operation of the nozzle 16 is controlled so that the corrected target opening is obtained.

  Here, FIG. 11 is a characteristic diagram showing the relationship between the flow rate of the exhaust gas flowing into the turbine 14 and the high-pressure EGR gas temperature when both the temperature of the collector 40 and the opening degree of the high-pressure EGR valve 51 are constant. is there. As described above, when the flow rate of the exhaust gas flowing into the turbine 14 is lowered, the turbine upstream gas temperature is lowered (see FIG. 5). Further, since the high-pressure EGR gas temperature decreases as the turbine upstream gas temperature decreases, the high-pressure EGR gas temperature decreases by reducing the flow rate of the exhaust gas flowing into the turbine 14 as shown in FIG. To do.

  And the process of step S200-202 is repeatedly performed until the high pressure EGR gas temperature becomes below predetermined value T2 (step S201 is NO), and the thermal damage of the high pressure EGR valve 51 and the high pressure EGR cooler 52 is avoided. Moreover, since the high-pressure EGR gas temperature can be lowered without changing the injection amount of the post injection, the temperature change of the collector 40 is suppressed even when step S202 is executed during the regeneration of the collector 40. Can do.

  As described above, according to the present embodiment, thermal damage to the high pressure EGR valve 51 and the high pressure EGR cooler 52 can be avoided while suppressing the temperature change of the collector 40.

  In step S202, the opening degree of the high pressure EGR valve 51 may be controlled instead of controlling the operation of the nozzle 16. Specifically, the opening degree of the high pressure EGR valve 51 when the high pressure EGR gas temperature exceeds the predetermined value T2 is smaller than the opening degree of the high pressure EGR valve 51 when the high pressure EGR gas temperature is equal to or lower than the predetermined value T2. Thus, the opening degree of the high pressure EGR valve 51 is controlled.

  Here, FIG. 12 is a characteristic diagram showing the relationship between the opening degree of the high pressure EGR valve 51 and the high pressure EGR gas temperature when the temperature of the collector 40 is constant. As shown in FIG. 12, when the opening degree of the high-pressure EGR valve 51 is reduced, the amount of high-pressure EGR gas, which is the circulation amount of the exhaust gas of the high-pressure EGR system, is reduced. The amount of heat released in the pipes increases until the high pressure EGR gas temperature reaches the high pressure EGR system part. Therefore, thermal damage to the high-pressure EGR system parts can be avoided. Moreover, since the high pressure EGR gas temperature can be lowered without changing the injection amount of the post injection, the temperature change of the collector 40 can be suppressed.

  Further, the high-pressure EGR gas temperature may be obtained as in the following d and e.

  (D) The vertical axis in FIG. 13 is the high-pressure EGR gas temperature drop that is the difference between the turbine upstream gas temperature and the high-pressure EGR gas temperature, and the horizontal axis is the turbine upstream gas temperature. Since the amount of heat release increases as the turbine upstream gas temperature increases, as shown in FIG. 13, the high pressure EGR gas temperature drop increases as the turbine upstream gas temperature increases.

  Therefore, in step S200, the turbine upstream gas temperature is estimated based on the turbine downstream gas temperature detected by the first exhaust temperature sensor 72, and the high pressure EGR gas temperature decrease amount is estimated based on the estimated turbine upstream gas temperature. The high pressure EGR gas temperature is estimated by subtracting the estimated value of the high pressure EGR gas temperature drop from the estimated value of the turbine upstream gas temperature.

  Since the amount of decrease in the high-pressure EGR gas temperature changes according to the turbine upstream gas temperature, the high-pressure EGR gas temperature can be estimated more accurately by doing so.

  (E) FIG. 14 is a characteristic diagram showing the relationship between the high-pressure EGR gas amount and the high-pressure EGR gas temperature decrease amount. As the high-pressure EGR gas amount decreases, the high-pressure EGR gas temperature decrease amount increases due to heat dissipation.

  Therefore, in step S200, the turbine upstream gas temperature is estimated based on the turbine downstream gas temperature detected by the first exhaust temperature sensor 72, the high-pressure EGR gas amount is calculated (details will be described later), and the calculated high-pressure EGR gas amount is calculated. Based on this, the high pressure EGR gas temperature drop is estimated, and the high pressure EGR gas temperature is estimated by subtracting the estimated value of the high pressure EGR gas temperature drop from the estimated value of the turbine upstream gas temperature.

  Since the amount of decrease in the high-pressure EGR gas temperature changes according to the amount of the high-pressure EGR gas, this makes it possible to estimate the high-pressure EGR gas temperature more accurately.

  The amount of high-pressure EGR gas can be determined as f and g below.

  (F) When the exhaust pressure sensor 71 is provided, the high pressure EGR is based on the exhaust pressure detected by the exhaust pressure sensor 71, the intake pressure detected by the intake pressure sensor 75, and the opening of the high pressure EGR valve 51. Find the gas volume.

  (G) When the low pressure EGR system is not provided, the calculation is performed according to the following procedure. First, the cylinder intake air amount is obtained based on the internal combustion engine rotational speed detected by the rotational speed sensor 76 and the intake pressure detected by the intake pressure sensor 75. Incidentally, the cylinder intake air amount ∝ number of revolutions × intake pressure. Next, the high-pressure EGR gas amount is obtained based on the intake flow rate (that is, the fresh air amount) detected by the air flow meter 74 and the cylinder intake air amount. Incidentally, high pressure EGR gas amount = cylinder intake air amount−new air amount.

(Third embodiment)
A third embodiment of the present invention will be described. In the first embodiment, it is possible to avoid thermal damage of the turbine 14 while suppressing the temperature change of the collector 40, whereas in this embodiment, the low pressure EGR is suppressed while suppressing the temperature change of the collector 40. This makes it possible to avoid thermal damage to system parts.

  In addition, since the whole structure of the control apparatus for internal combustion engines of this embodiment is the same as the whole structure of the control apparatus for internal combustion engines of 1st Embodiment, this embodiment is demonstrated below, referring FIG.

  FIG. 15 is a flowchart showing the damage avoidance control process executed by the ECU 80 in the control device of the present embodiment. This process starts when the key switch is operated to the on position in order to operate the internal combustion engine 1. When the key switch is operated to the off position in order to stop the internal combustion engine 1, the process is terminated.

  As shown in FIG. 15, first, in step S300 as the low pressure EGR gas temperature acquisition means, the low pressure EGR gas temperature that is the temperature of the exhaust gas in the low pressure EGR passage 60 is estimated. More specifically, the temperature of the exhaust gas between the low pressure EGR valve 61 and the low pressure EGR cooler 62 is estimated.

  Here, FIG. 16 is a characteristic diagram showing the relationship between the oxidation catalyst downstream gas temperature, which is the temperature of the exhaust gas between the oxidation catalyst 41 and the branch portion of the low pressure EGR passage 60, and the low pressure EGR gas temperature. The low pressure EGR gas temperature increases as the catalyst downstream gas temperature increases. Therefore, in the present embodiment, the low pressure EGR gas temperature is estimated based on the oxidation catalyst downstream gas temperature detected by the second exhaust temperature sensor 73.

  A map defining the relationship between the low-pressure EGR gas temperature and the oxidation catalyst downstream gas temperature shown in FIG. 16 is stored in the ROM of the ECU 80, and the oxidation catalyst downstream gas temperature can be obtained from the map.

  In the next step S301, the low pressure EGR gas temperature estimated in step S300 is compared with a predetermined value T3. If the low pressure EGR gas temperature is equal to or lower than the predetermined value T3 (NO in step S301), the damage avoidance control process is temporarily ended. .

  On the other hand, when the low pressure EGR gas temperature estimated in step S300 exceeds the predetermined value T3 (YES in step S301), in other words, the low pressure EGR valve 61 and the low pressure EGR cooler 62 may be thermally damaged. Sometimes, the process proceeds to step S302.

  In step S302 as the low pressure EGR gas temperature lowering means, control is performed to lower the low pressure EGR gas temperature. In the present embodiment, the opening degree of the low pressure EGR valve 61 when the low pressure EGR gas temperature exceeds the predetermined value T3 is smaller than the opening degree of the low pressure EGR valve 61 when the low pressure EGR gas temperature is equal to or lower than the predetermined value T3. Thus, the opening degree of the low pressure EGR valve 61 is controlled.

  More specifically, a map that defines the target opening degree of the low pressure EGR valve 61 (adapted value when the low pressure EGR gas temperature is equal to or lower than the predetermined value T3) with respect to the engine speed and the accelerator opening degree is stored in the ROM of the ECU 80. When the low-pressure EGR gas temperature is equal to or lower than the predetermined value T3, the target opening is obtained from the map based on the engine speed and the accelerator opening, and the low-pressure EGR valve 61 is controlled so as to be the target opening. On the other hand, when the low-pressure EGR gas temperature exceeds a predetermined value T3, the target opening is obtained from the map based on the internal combustion engine speed and the accelerator opening, and the target opening is corrected so that the opening becomes small, The low pressure EGR valve 61 is controlled so as to achieve the corrected target opening.

  Here, FIG. 17 is a characteristic diagram showing the relationship between the opening degree of the low-pressure EGR valve 61 and the low-pressure EGR gas temperature when the temperature of the collector 40 is constant. As shown in FIG. 17, when the opening of the low-pressure EGR valve 61 is reduced, the amount of low-pressure EGR gas, which is the circulation amount of the exhaust gas of the low-pressure EGR system, is reduced. The amount of heat radiation in the pipes up to this point increases, and the temperature of the low pressure EGR gas when it reaches the low pressure EGR system part decreases.

  And the process of step S300-302 is repeatedly performed until the low pressure EGR gas temperature becomes below predetermined value T3 (step S301 is NO), and the thermal damage of the low pressure EGR valve 61 or the low pressure EGR cooler 62 is avoided. Moreover, since the low-pressure EGR gas temperature can be lowered without changing the injection amount of the post injection, the temperature change of the collector 40 is suppressed even if step S302 is executed during the regeneration of the collector 40. Can do.

  As described above, according to the present embodiment, thermal damage to the low pressure EGR valve 61 and the low pressure EGR cooler 62 can be avoided while suppressing a temperature change of the collector 40.

  Note that the low-pressure EGR gas temperature may be obtained as in the following h and i.

  (H) The vertical axis in FIG. 18 is the low-pressure EGR gas temperature drop that is the difference between the oxidation catalyst downstream gas temperature and the low-pressure EGR gas temperature, and the horizontal axis is the oxidation catalyst downstream gas temperature. As the oxidation catalyst downstream gas temperature increases, the amount of heat release increases, and as shown in FIG. 18, the low pressure EGR gas temperature decrease amount increases as the oxidation catalyst downstream gas temperature increases.

  Therefore, in step S300, the low pressure EGR gas temperature decrease amount is estimated based on the oxidation catalyst downstream gas temperature detected by the second exhaust temperature sensor 73, and the estimated value of the low pressure EGR gas temperature decrease amount is subtracted from the oxidation catalyst downstream gas temperature. Thus, the low pressure EGR gas temperature is estimated.

  Since the amount of decrease in the low-pressure EGR gas temperature changes in accordance with the oxidation catalyst downstream gas temperature, this makes it possible to estimate the low-pressure EGR gas temperature more accurately.

  (I) FIG. 19 is a characteristic diagram showing the relationship between the low pressure EGR gas temperature drop amount and the low pressure EGR gas amount, and the lower the low pressure EGR gas amount, the greater the low pressure EGR gas temperature drop amount due to heat dissipation.

  Therefore, in step S300, the low pressure EGR gas amount is calculated (details will be described later), the low pressure EGR gas temperature drop amount is estimated based on the calculated low pressure EGR gas amount, and the downstream of the oxidation catalyst detected by the second exhaust temperature sensor 73 is calculated. The low pressure EGR gas temperature is estimated by subtracting the estimated value of the low pressure EGR gas temperature drop from the gas temperature.

  Since the amount of decrease in the low-pressure EGR gas temperature changes in accordance with the amount of low-pressure EGR gas, this makes it possible to estimate the low-pressure EGR gas temperature more accurately.

  The amount of low-pressure EGR gas is calculated according to the following procedure. First, the cylinder intake air amount is obtained based on the internal combustion engine rotational speed detected by the rotational speed sensor 76 and the intake pressure detected by the intake pressure sensor 75.

  Next, the total EGR gas amount (that is, the high pressure EGR gas amount + the low pressure EGR gas amount) is obtained based on the intake flow rate (that is, the fresh air amount) detected by the air flow meter 74 and the cylinder intake air amount. Incidentally, the total EGR gas amount = cylinder intake air amount−new air amount.

  Next, the high pressure EGR gas amount is obtained based on the exhaust pressure, the intake pressure, and the opening degree of the high pressure EGR valve 51. Then, the low pressure EGR gas amount is obtained by subtracting the high pressure EGR gas amount from the total EGR gas amount.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In the first embodiment, thermal damage to the turbine 14 can be avoided while suppressing the temperature change of the collector 40, whereas in the present embodiment, the intake pressure is suppressed while suppressing the temperature change of the collector 40. This makes it possible to prevent the turbocharger 13 and the internal combustion engine 1 from being damaged due to the abnormal rise.

  In addition, since the whole structure of the control apparatus for internal combustion engines of this embodiment is the same as the whole structure of the control apparatus for internal combustion engines of 1st Embodiment, this embodiment is demonstrated below, referring FIG.

  FIG. 20 is a flowchart showing an intake pressure abnormality control process executed by the ECU 80 in the control device of the present embodiment. This process is started when regeneration of the collector 40 is started. When the playback of is completed, it ends.

  As shown in FIG. 20, first, in step S400 as the regeneration intake pressure acquisition means, the intake pressure sensor 75 detects the intake pressure downstream of the compressor 15.

  In the next step S401, the intake pressure detected in step S400 is compared with a predetermined value High, and if the intake pressure is equal to or lower than the predetermined value High (step S401 is YES), the control process at the time of abnormal intake pressure is temporarily ended.

  On the other hand, when the intake pressure detected in step S400 exceeds the predetermined value High (NO in step S401), in other words, there is a risk of damage to the turbocharger 13 or the internal combustion engine 1 due to an abnormal increase in intake pressure. In step S402, the process proceeds to step S402.

  In step S402 as intake pressure lowering means, control for lowering the intake pressure is performed. In this embodiment, the intake pressure is lowered by controlling the injection amount and injection timing of post injection as follows.

  FIG. 21 shows the nozzle lift amount of the fuel injection valve 12 with respect to the crank angle. The broken line shows the control characteristics when the intake pressure is equal to or less than the predetermined value High, and the solid line shows when the intake pressure exceeds the predetermined value High. The control characteristics are shown. FIG. 22 shows the heat generation rate of the internal combustion engine 1 with respect to the crank angle when the injection amount and the injection timing of the post injection are controlled as shown in FIG. 21, and the broken line indicates the intake pressure is below a predetermined value High. The solid line shows the characteristic when the intake pressure exceeds the predetermined value High.

  As shown in FIG. 21, post injection is performed three times after main injection. In step S402, the first post-injection reduces the injection amount and retards the injection timing as compared to the first post-injection when the intake pressure is equal to or lower than the predetermined value High. Further, the second post-injection makes the injection amount equal and retards the injection timing as compared to the second post-injection when the intake pressure is equal to or lower than the predetermined value High. Further, the third post-injection increases the injection amount and retards the injection timing as compared with the third post-injection when the intake pressure is equal to or lower than the predetermined value High.

  More specifically, a map that defines the injection amount and the injection timing of the post-injection with respect to the internal combustion engine speed and the accelerator opening (applicable value when the intake pressure is equal to or lower than the predetermined value High) is stored in the ROM of the ECU 80. When the intake pressure is less than or equal to the predetermined value High, the injection amount and the injection timing of the post-injection are determined from the map based on the internal combustion engine speed and the accelerator opening, and the fuel injection valve is set so as to be the determined injection amount and the injection timing 12 operations are controlled. On the other hand, when the intake pressure exceeds a predetermined value High, the post-injection injection amount and injection timing are obtained from the map based on the internal combustion engine speed and the accelerator opening, and the obtained injection amount and injection timing are related to each other as described above. And the operation of the fuel injection valve 12 is controlled so that the corrected injection amount and injection timing are obtained.

  In this way, by reducing the injection amount of the post injection with the earlier injection timing, the amount of fuel combusted in the cylinder is reduced. In addition, by delaying the injection timing of the post injection, the post injection with the early injection timing misfires, and the post injection with the late injection timing is not combusted in the cylinder. Therefore, as shown in FIG. 22, the heat generation rate in the post-injection region decreases, the exhaust pressure decreases, the work of the turbocharger 13 decreases, and the intake pressure decreases.

  Then, the processes in steps S400 to 402 are repeatedly executed until the intake pressure becomes equal to or lower than the predetermined value High (YES in step S401), and the turbocharger 13 and the internal combustion engine 1 are prevented from being damaged due to an abnormal increase in the intake pressure. . Further, since the intake pressure can be reduced without changing the total injection amount of the post injection, the temperature change of the collector 40 can be suppressed even if step S402 is executed during the regeneration of the collector 40. it can.

  As described above, according to the present embodiment, it is possible to prevent the turbocharger 13 and the internal combustion engine 1 from being damaged due to an abnormal increase in intake pressure while suppressing the temperature change of the collector 40.

  In step S402, the intake pressure is reduced by changing the injection amount and the injection timing of the post-injection. However, in step S402, the intake pressure may be reduced as j and k below.

  (J) FIG. 23 is a characteristic diagram showing the relationship between the opening degree of the intake throttle valve 22 and the intake pressure, and the intake pressure decreases as the opening degree of the intake throttle valve 22 decreases. Therefore, in step S402, the intake pressure is lowered by making the opening of the intake throttle valve 22 smaller than when the intake pressure is less than or equal to the predetermined value High.

  (K) In step S402, the work flow of the turbocharger 13 is reduced to lower the intake pressure by lowering the flow rate of the exhaust gas flowing into the turbine 14 than when the intake pressure is equal to or less than the predetermined value High. .

(Fifth embodiment)
A fifth embodiment of the present invention will be described. In the first embodiment, thermal damage to the turbine 14 can be avoided while suppressing the temperature change of the collector 40, whereas in the present embodiment, the intake pressure is suppressed while suppressing the temperature change of the collector 40. This makes it possible to prevent the oil from rising due to an abnormal drop in oil.

  In addition, since the whole structure of the control apparatus for internal combustion engines of this embodiment is the same as the whole structure of the control apparatus for internal combustion engines of 1st Embodiment, this embodiment is demonstrated below, referring FIG.

  FIG. 24 is a flowchart showing a control process at the time of abnormal intake pressure executed by the ECU 80 in the control device of the present embodiment. This process is started when regeneration of the collector 40 is started, and the collector 40 When the playback of is completed, it ends.

  As shown in FIG. 24, first, in step S500 as a regeneration intake pressure acquisition means, the intake pressure sensor 75 detects the intake pressure downstream of the compressor 15.

  In the next step S501, the intake pressure detected in step S500 is compared with a predetermined value Plow. If the intake pressure is greater than or equal to the predetermined value Plow (YES in step S501), the control process for abnormal intake pressure is temporarily ended.

  On the other hand, when the intake pressure detected in step S500 is less than the predetermined value Plow (NO in step S501), in other words, when there is a possibility that an increase in oil due to an abnormal decrease in intake pressure may occur, the process proceeds to step S502.

  In step S502 as intake pressure increasing means, control for increasing the intake pressure is performed. In the present embodiment, the intake pressure is increased by controlling the injection amount and injection timing of post injection as follows.

  When post injection is performed three times after main injection, in step S502, the first post injection increases the injection amount and injects compared to the first post injection when the intake pressure is equal to or higher than the predetermined value Plow. Advance the time. Further, the second post-injection makes the injection amount equal and advances the injection timing compared to the second post-injection when the intake pressure is equal to or higher than the predetermined value Plow. Further, the third post-injection reduces the injection amount and advances the injection timing compared to the third post-injection when the intake pressure is equal to or higher than the predetermined value Plow.

  More specifically, a map that defines post-injection injection amount and injection timing (applicable value when the intake pressure is equal to or higher than a predetermined value Plow) with respect to the internal combustion engine speed and the accelerator opening is stored in the ROM of the ECU 80. When the intake pressure is equal to or greater than a predetermined value Plow, the injection amount and the injection timing of the post-injection are obtained from the map based on the engine speed and the accelerator opening, and the fuel injection valve is set so as to obtain the obtained injection amount and the injection timing. 12 operations are controlled. On the other hand, when the intake pressure is less than the predetermined value Plow, the post-injection injection amount and injection timing are obtained from the map based on the internal combustion engine speed and the accelerator opening, and the obtained injection amount and injection timing are in the relationship described above. The operation of the fuel injection valve 12 is controlled so that the corrected injection amount and injection timing are obtained.

  In this way, by increasing the injection amount of the post injection having an earlier injection timing, the amount of fuel combusted in the cylinder increases. Moreover, misfire of post injection is prevented by advancing the injection timing of post injection. Therefore, the heat generation rate in the post-injection region is increased, the exhaust pressure is increased, the work amount of the turbocharger 13 is increased, and the intake pressure is increased.

  Then, the processes in steps S500 to S502 are repeatedly executed until the intake pressure becomes equal to or higher than the predetermined value Plow (YES in step S501), and oil rise due to an abnormal decrease in intake pressure is prevented. Further, since the intake pressure can be increased without changing the total injection amount of the post injection, the temperature change of the collector 40 can be suppressed even if step S402 is executed during the regeneration of the collector 40. it can.

  As described above, according to the present embodiment, it is possible to prevent the oil from rising due to an abnormal decrease in the intake pressure while suppressing the temperature change of the collector 40.

  In step S502, the intake pressure is increased by changing the injection amount and the injection timing of the post injection. However, in step S502, the intake pressure may be increased as in the following l and m.

  (L) In step S502, the opening of the intake throttle valve 22 is made larger than when the intake pressure is greater than or equal to the predetermined value Plow to increase the intake pressure.

  (M) In step S502, the work flow of the turbocharger 13 is increased by increasing the flow rate of the exhaust gas flowing into the turbine 14 than when the intake pressure is greater than or equal to the predetermined value Plow, thereby increasing the intake pressure. .

(Other embodiments)
In each said embodiment, although the collector 40 and the oxidation catalyst 41 were provided independently, you may use the collector which carry | supported the oxidation catalyst.

  In each of the above embodiments, the collector 40 is used as a post-treatment device. However, the present invention uses an NOx storage reduction catalyst for purifying nitrogen oxide (hereinafter referred to as NOx) in exhaust gas as a post-treatment device. It can be applied to the case of using as. Incidentally, when the NOx storage reduction catalyst is used, the NOx catalyst is regenerated by supplying unburned HC to the NOx catalyst and reducing and releasing the stored NOx.

1 is a diagram illustrating an overall configuration of a control device for an internal combustion engine according to a first embodiment of the present invention. It is a figure which shows typically the structure of the turbine 14 of FIG. It is a flowchart which shows the damage avoidance control process performed in ECU80 of FIG. It is a characteristic view which shows the relationship between turbine downstream gas temperature and turbine upstream gas temperature. FIG. 6 is a characteristic diagram showing the relationship between the flow rate of exhaust gas flowing into the turbine 14 and the turbine upstream gas temperature. It is a characteristic view which shows the relationship between turbine downstream gas temperature and turbine front-and-back temperature difference. FIG. 6 is a characteristic diagram showing the relationship between the flow rate of exhaust gas flowing into the turbine 14 and the temperature difference before and after the turbine. It is a map of the temperature difference before and behind a turbine. It is a flowchart which shows the damage avoidance control process performed in ECU80 in the control apparatus of 2nd Embodiment. It is a characteristic view which shows the relationship between turbine downstream gas temperature and high pressure EGR gas temperature. FIG. 6 is a characteristic diagram showing the relationship between the flow rate of exhaust gas flowing into the turbine 14 and the high-pressure EGR gas temperature. It is a characteristic view which shows the relationship between the opening degree of the high pressure EGR valve 51, and the high pressure EGR gas temperature. It is a characteristic view which shows the relationship between turbine upstream gas temperature and high pressure EGR gas temperature fall amount. It is a characteristic view which shows the relationship between high pressure EGR gas amount and high pressure EGR gas temperature fall amount. It is a flowchart which shows the damage avoidance control process performed by ECU80 in the control apparatus of 3rd Embodiment. It is a characteristic view which shows the relationship between oxidation catalyst downstream gas temperature and low-pressure EGR gas temperature. It is a characteristic view which shows the relationship between the opening degree of the low pressure EGR valve 61, and the low pressure EGR gas temperature. It is a characteristic view which shows the relationship between an oxidation catalyst downstream gas temperature and the low pressure EGR gas temperature fall amount. It is a characteristic view which shows the relationship between the low pressure EGR gas temperature fall amount and the low pressure EGR gas amount. It is a flowchart which shows the control processing at the time of the intake pressure abnormality performed by ECU80 in the control apparatus of 4th Embodiment. It is a figure which shows the control characteristic of the nozzle lift in the control apparatus of 4th Embodiment. It is a figure which shows the characteristic of the heat release rate in the control apparatus of 4th Embodiment. FIG. 6 is a characteristic diagram showing the relationship between the opening of the intake throttle valve 22 and the intake pressure. It is a flowchart which shows the control processing at the time of the intake pressure abnormality performed by ECU80 in the control apparatus of 5th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 13 ... Turbocharger, 14 ... Turbine, 16 ... Nozzle, 40 ... Collector (post-processing apparatus).

Claims (4)

A turbocharger (13) that controls the flow rate when exhaust gas flows into the turbine (14) by a nozzle (16), and an exhaust system that is disposed downstream of the turbine (14) in the exhaust gas. An internal combustion engine that is mounted on an internal combustion engine (1) that includes a post-processing device (40) that processes harmful substances, and that performs post-injection in the exhaust stroke of the internal combustion engine (1) to regenerate the post-processing device (40). An engine control device,
Turbine upstream gas temperature acquisition means (S100) for acquiring information of turbine upstream gas temperature, which is the temperature of exhaust gas upstream of the turbine (14);
When the value of the turbine upstream gas temperature acquired by the turbine upstream gas temperature acquisition means (S100) exceeds a predetermined value, the turbine (14) is more than when the value of the turbine upstream gas temperature is equal to or lower than the predetermined value. Turbine upstream gas temperature lowering means (S102) for controlling the operation of the nozzle (16) so that the flow rate of the exhaust gas flowing into the
And an exhaust temperature sensor (72) for detecting a turbine downstream gas temperature, which is a temperature of exhaust gas between the turbine (14) and the aftertreatment device (40),
The turbine upstream gas temperature acquisition means (S100) estimates the turbine upstream gas temperature based on the turbine downstream gas temperature detected by the exhaust temperature sensor (72). A turbocharger (13) that controls the flow rate when exhaust gas flows into the turbine (14) by a nozzle (16), and an exhaust system that is disposed downstream of the turbine (14) in the exhaust gas. An internal combustion engine that is mounted on an internal combustion engine (1) that includes a post-processing device (40) that processes harmful substances, and that performs post-injection in the exhaust stroke of the internal combustion engine (1) to regenerate the post-processing device (40). An engine control device,
Turbine upstream gas temperature acquisition means (S100) for acquiring information of turbine upstream gas temperature, which is the temperature of exhaust gas upstream of the turbine (14);
When the value of the turbine upstream gas temperature acquired by the turbine upstream gas temperature acquisition means (S100) exceeds a predetermined value, the turbine (14) is more than when the value of the turbine upstream gas temperature is equal to or lower than the predetermined value. Turbine upstream gas temperature lowering means (S102) for controlling the operation of the nozzle (16) so that the flow rate of the exhaust gas flowing into the
Further, the turbine upstream gas temperature acquisition means (S100) acquires information on the turbine downstream gas temperature that is the temperature of the exhaust gas between the turbine (14) and the aftertreatment device (40). An acquisition means, and a turbine front-rear temperature difference acquisition means for acquiring information on a turbine front-rear temperature difference, which is a difference between the turbine upstream gas temperature and the turbine downstream gas temperature,
The turbine upstream gas temperature acquisition unit (S100) adds the turbine front-rear temperature difference acquired by the turbine front-rear temperature difference acquisition unit to the turbine downstream gas temperature acquired by the turbine downstream gas temperature acquisition unit, and A control apparatus for an internal combustion engine, characterized by estimating a turbine upstream gas temperature. 3. The turbine front-rear temperature difference is estimated based on at least one of the turbine downstream gas temperature and the operating position of the nozzle (16). Control device for internal combustion engine. The turbine front-rear temperature difference acquisition means calculates the turbine front-rear temperature difference based on an opening of an intake throttle valve (22) that opens and closes an intake system passage and an intake pressure downstream of the intake throttle valve (22). The control device for an internal combustion engine according to claim 2 , wherein the control device is estimated.

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