DE102017106577B4 - Control device and control method for an internal combustion engine - Google Patents

Abstract

A control device for an internal combustion engine (1), the internal combustion engine (1) comprising: an intercooler (6) configured to cool an intake air to be supplied to the internal combustion engine (1) by heat exchange with a coolant, an electric pump ( 42) configured to adjust a flow rate of the coolant circulating through the charge air cooler (6), an intake air temperature sensor (16) configured to sense a parameter value associated with a temperature of the intake air flowing through the charge air cooler (6) is correlated, a catalyst (20) configured to store and reduce NOx in an exhaust gas of the internal combustion engine (1), and a temperature humidity sensor (18, 19) configured to an outside air temperature and a To detect outside air humidity, the control device being characterized by an electronic control ngs unit (8), which is configured: to obtain an engine speed of the internal combustion engine (1); to calculate a target fuel injection amount of the internal combustion engine (1); to determine whether an operating mode of the internal combustion engine (1) is a NOx reduction mode or not, wherein the NOx reduction mode is a mode in which an air-fuel ratio of the internal combustion engine (1) is changed to a rich side to reduce the NOx stored in the catalyst (20); a first target value (T1) for calculate a setpoint of the parameter value when the mode is not the NOx reduction mode, the first setpoint being calculated based on the engine speed and the target fuel injection amount to be set when the mode is not the NOx reduction mode; a second setpoint ( T2) to be calculated for the setpoint if the operating mode is the NOx reducing mode, w the second target value (T2) is calculated based on the engine speed and the target fuel injection amount to be set when the mode is the NOx reduction mode, the second target value (T2) being a value larger than the first target value (T1 ) that is calculated under the same engine speed and target fuel injection amount conditions; calculate a third target value (T3) for the target value based on the engine speed, the target fuel injection amount to be set in the particular mode, and the detected outside air temperature and outside humidity , the third setpoint (T3) being a setpoint at which the temperature of the intake air cooled by the charge air cooler (6) is higher than a condensation temperature; a higher value from the first setpoint (T1) and the third setpoint ( T3) as a final setpoint when the electronic tax determining unit (8) determines that the mode is not the NOx reducing mode; setting a higher value from the second target value (T2) and the third target value (T3) than the final target value when the electronic control unit (8) determines that the Operating mode is the NOx reduction mode; andcarry out control at a speed of the electric pump (42) so that the parameter value reaches the set final target value.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

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

Description of the Related Art

The Japanese patent publication JP 2011 - 214 544 A. describes a technique for controlling an electric pump that adjusts a flow rate of a coolant that circulates through an intercooler, such that a temperature of an intake air that is cooled by the intercooler reaches a target value that is based on an operating state of an internal combustion engine.

The publication DE 10 2012 011 991 A1 describes a method for operating a metering valve and an internal combustion engine. The internal combustion engine includes a charge air cooler for cooling charge air and the metering valve. The charge air comprises exhaust gases which are directed from an exhaust tract of the internal combustion engine to the charge air cooler via an adjustable exhaust gas recirculation rate. In the method, a metering valve temperature of the metering valve is determined and a charge air temperature of the charge air is recorded. Depending on the metering valve temperature, coolant is supplied to the metering valve and the charge air cooler by means of a jointly adjustable coolant pump. Furthermore, an exhaust gas recirculation rate is set depending on the charge air temperature and the metering valve temperature.

The publication DE 10 2014 119 504 A1 describes a system and method for controlling an exhaust aftertreatment device for a vehicle. The method includes: determining, by a control unit, signals from a front lambda sensor and a rear lambda sensor of a lean NOx trap when an internal combustion engine is operated in a rich mode, and detecting, by the control unit, a temperature of exhaust gas , determined by a temperature sensor when the internal combustion engine is operated in a rich mode. The method further includes comparing, by the control unit, the signals from the front lambda probe and the rear lambda probe to determine a breakthrough time when there is a breakthrough between the signals from the front lambda probe and the rear lambda probe. In addition, the control unit is configured to determine an additional rich duration based on the breakthrough time and the temperature of exhaust gas.

SUMMARY OF THE INVENTION

An operating mode of an internal combustion engine includes a normal operating mode and a NOx reduction mode. In the normal mode, combustion is performed at an air-fuel ratio that corresponds to an operating state that is requested by the internal combustion engine. In the NOx reduction mode, the air-fuel ratio is changed to a rich side to carry out combustion. In the normal mode, the air-fuel ratio is variably set based on a viewpoint to ensure an output of the internal combustion engine and prevention of deterioration of an emission. In the NOx reduction mode, combustion is carried out at a rich air-fuel ratio to reduce NOx, which is stored in a catalyst that purifies an exhaust gas from the internal combustion engine.

From the viewpoint of ensuring the output of the internal combustion engine and preventing the deterioration of the emission, it is desirable that the temperature of the intake air cooled by the charge air cooler is low. For this reason, it is desirable to set a target value of the intake air temperature to a low value.

However, rich combustion is carried out in the NOx reducing mode. As a result, in an operating state in which a requested torque in the internal combustion engine is small, for example, a fuel injection amount becomes small, and the intake air is also largely reduced. In such a NOx reduction mode, if the target value of the intake air temperature is also set to a low value based on the position to ensure the output of the internal combustion engine and to prevent the deterioration of the emission, the intake air temperature is too low and the intake air cannot be reduced so that the rich combustion cannot be realized and NOx cannot be reduced.

Further, if the temperature of the intake air cooled by the charge air cooler is too low, the intake air temperature falls below a condensation temperature, whereby condensed water can be generated in the charge air cooler. When condensed water is generated, the condensed water thus generated collects in an intake duct and then flows into a cylinder Internal combustion engine at a time, which can cause a water hammer phenomenon.

In view of this, the present invention provides a control device and method for an internal combustion engine, each of which limits condensed water generation in an intercooler and controls an optimal intake air temperature according to an operation mode of the internal combustion engine.

A first embodiment of the present invention is a control device for an internal combustion engine. The internal combustion engine includes a charge air cooler, an electric pump, an intake air temperature sensor, a catalytic converter and a temperature humidity sensor. The charge air cooler is configured to cool an intake air to be supplied to the internal combustion engine by heat exchange with a coolant. The electric pump is configured to adjust a flow rate of the coolant circulating through the charge air cooler. The intake air temperature sensor is configured to sense a parameter value that is correlated with a temperature of the intake air that is cooled by the charge air cooler. The catalyst is configured to store and reduce NOx in an exhaust gas of the internal combustion engine. The temperature humidity sensor is configured to detect an outside air temperature and an outside air humidity. The control device comprises an electronic control unit. The electronic control unit is configured to obtain or obtain an engine speed of the internal combustion engine and to calculate a target fuel injection quantity of the internal combustion engine. The electronic control unit is configured to determine whether the operating mode of the internal combustion engine is a NOx reduction mode or not. The NOx reduction mode is a mode in which an air-fuel ratio of the internal combustion engine is changed to a rich side to reduce the NOx stored in the catalyst. The electronic control unit is configured to calculate a first setpoint for a setpoint of the parameter value if the operating mode is not the NOx reduction mode. The first target value is calculated based on the engine speed and the target fuel injection amount to be set when the mode is not the NOx reduction mode. The electronic control unit is configured to calculate a second setpoint for the setpoint if the operating mode is the NOx reduction mode. The second target value is calculated based on the engine speed and the target fuel injection amount to be set when the mode is the NOx reduction mode. The second target value is a value that is larger than the first target value that is set under the same conditions of the engine speed and the target fuel injection amount. The electronic control unit is configured to calculate a third target value for the target value based on the engine speed of the target fuel injection quantity to be set in the specific operating mode and a detected outside air temperature and a detected outside air humidity. The third setpoint is a setpoint at which the temperature of the intake air cooled by the charge air cooler is higher than a condensation temperature. The electronic control unit is configured to set a higher value from the first target value and the third target value than a final target value when the electronic control unit determines that the operating mode is not the NOx reduction mode. The electronic control unit is configured to set a higher value from the second target value and the third target value than the final target value when the electronic control unit determines that the operating mode is the NOx reduction mode. The electronic control unit is configured to regulate the speed of the electric pump so that the parameter value reaches the set final setpoint.

According to the configuration described above, when the mode is not the NOx reduction mode, a higher value of the first target value and the third target value that exceeds the condensation temperature is set than the final target value, and the control is performed on the speed of the electric pump to reach the setpoint. This controls an intake air temperature to an intake air temperature suitable for the non-NOx reduction mode within a range in which no condensed water is generated in the charge air cooler. Further, in the case of the NOx reducing mode, a higher value from the second target value in the NOx reducing mode and the third target value that exceeds the condensation temperature is set as the final target value, and the control is performed at the speed of the electric pump to to reach the setpoint. This allows the intake air temperature to be controlled to an intake air temperature suitable for reducing NOx stored in the catalyst within a range in which no condensed water is generated in the charge air cooler.

The electronic control unit can be configured in the control device, the first setpoint, the second setpoint and the third Calculate the setpoint independently of a determination result of the operating mode

In the control device, the electronic control unit may be configured not to calculate the first target value when the electronic control unit determines that the operating mode is the NOx reduction mode. The electronic control unit may be configured not to calculate the second setpoint when the electronic control unit determines that the mode is not the NOx reduction mode.

A second embodiment of the present invention is a control method for an internal combustion engine. The internal combustion engine includes a charge air cooler, an electric pump, an intake air temperature sensor, a catalytic converter and a temperature humidity sensor. The charge air cooler is configured to cool an intake air to be supplied to the internal combustion engine by heat exchange with a coolant. The electric pump is configured to adjust a flow rate of the coolant circulating through the charge air cooler. The intake air temperature sensor is configured to detect a parameter value that correlates with a temperature of the intake air that is cooled by the charge air cooler. The catalyst is configured to store and reduce NOx in an exhaust gas of the internal combustion engine. The temperature humidity sensor is configured to detect an outside air temperature and an outside air humidity. The control method includes: calculating a target fuel injection amount of the internal combustion engine; determining whether or not an engine operating mode is a NOx reduction mode, the NOx reduction mode being a mode in which an air-fuel ratio of the engine is changed to a rich side by the NOx contained in the catalyst is saved to reduce; calculating a first setpoint for a setpoint of the parameter value when the mode is not the NOx reduction mode, the first setpoint based on an engine speed of the internal combustion engine and the target fuel injection amount to be set when the mode is not the NOx reduction mode, is calculated; calculating a second setpoint for the setpoint when the mode is the NOx reduction mode, the second setpoint being calculated based on the engine speed and the target fuel injection amount to be set when the mode is the NOx reduction mode, the second Target value is greater than the first target value calculated under the same engine speed and target fuel injection quantity conditions; calculating a third setpoint for the setpoint based on the engine speed, the target fuel injection amount to be set in the particular mode, and the detected outside air temperature and outside humidity, the third setpoint being a setpoint at which the temperature of the intake air, the is cooled by the charge air cooler is higher than a condensation temperature; setting a higher value from the first target value and the third target value than a final target value if the operating mode is not the NOx reduction mode; setting a higher value of the second target value and the third target value than the final target value when the operating mode is the NOx reduction mode; and performing control on the speed of the electric pump so that the parameter value reaches the set final target value.

According to the configuration described above, it is possible to provide a control device for an internal combustion engine, the control device limiting generation of condensed water in an intercooler and controlling an optimal intake air temperature according to an operating mode of the internal combustion engine.

list of figures

• 1 eine Darstellung, die eine Steuerungsvorrichtung für eine Verbrennungskraftmaschine gemäß dem vorliegenden Ausführungsbeispiel veranschaulicht;
• 2 ein Flussdiagramm, das ein Beispiel einer Einstellungssteuerung eines Sollwerts einer Einlasslufttemperatur veranschaulicht, die durch eine ECU auszuführen ist;
• 3A ein Flussdiagramm, das ein Beispiel eines ersten Sollwertberechnungsschritts veranschaulicht;
• 3B ein Beispiel einer Abbildung bzw. eines Kennfelds, die eine Solltemperatur als einen ersten Sollwert entsprechend einer Kraftmaschinendrehzahl und einer Sollkraftstoffeinspritzmenge, die in einer normalen Betriebsart eingestellt wird, vorschreibt;
• 4A ein Flussdiagramm, das ein Beispiel eines zweiten Sollwertberechnungsschritts veranschaulicht;
• 4B ein Beispiel einer Abbildung bzw. eines Kennfelds, die eine Solltemperatur als einen zweiten Sollwert entsprechend einer Kraftmaschinendrehzahl und einer Sollkraftstoffeinspritzmenge, die in einer NOx-Reduzierbetriebsart eingestellt wird, vorschreibt;
• 5 ein Flussdiagramm, das ein Beispiel eines dritten Sollwertberechnungsschritts veranschaulicht;
• 6 ein Beispiel einer Abbildung bzw. eines Kennfelds, das eine Kondensationstemperatur entsprechend einer Außenlufttemperatur und einer Außenluftfeuchtigkeit bei einem vorbestimmten Sollladedruck vorschreibt; und
• 7 ein Flussdiagramm, das eine Modifikation einer Einstellungssteuerung eines Sollwerts einer Einlasslufttemperatur veranschaulicht, die durch die ECU auszuführen ist.

Features, advantages and a technical and industrial meaning of exemplary embodiments of the invention are described below with reference to the accompanying drawing, in which like reference numerals designate like elements. Show it:

• 1 a diagram illustrating a control device for an internal combustion engine according to the present embodiment;
• 2 14 is a flowchart illustrating an example of setting control of a target value of intake air temperature to be executed by an ECU;
• 3A a flowchart illustrating an example of a first setpoint calculation step;
• 3B an example of a map that prescribes a target temperature as a first target value corresponding to an engine speed and a target fuel injection amount set in a normal mode;
• 4A a flowchart illustrating an example of a second target value calculation step;
• 4B an example of a map or a map that a target temperature as prescribes a second target value corresponding to an engine speed and a target fuel injection amount set in a NOx reduction mode;
• 5 a flowchart illustrating an example of a third target value calculation step;
• 6 an example of a map or a map that prescribes a condensation temperature corresponding to an outside air temperature and an outside air humidity at a predetermined target boost pressure; and
• 7 14 is a flowchart illustrating a modification of setting control of a target value of an intake air temperature to be executed by the ECU.

DETAILED DESCRIPTION OF THE EMBODIMENTS

1 shows an illustration showing a control device for an internal combustion engine 1 illustrated according to the present embodiment. The control device for the internal combustion engine 1 includes an exhaust duct 3 , an intake duct 4 , a charger 5 , an intercooler 6 , an electronic control unit (ECU 8th ), a catalyst 20 , a bypass channel 30 and the same. The internal combustion engine 1 is a diesel engine that has four cylinders 2 includes, but is not limited to, and may be a gasoline engine. The intake duct 4 and the exhaust duct 3 are with the internal combustion engine 1 connected. A compressor housing 51 of the charger 5 is in the middle of the intake duct 4 placed. A turbine casing 50 of the charger 5 is in the middle of the exhaust duct 3 placed.

A turbine 500 is in the turbine housing 50 placed and a compressor 501 is in the compressor housing 51 placed. The turbine 500 and the compressor 501 are connected coaxially by a turbine shaft. The compressor 501 is also through the turbine 500 rotated, which is rotated by an exhaust gas passing through the exhaust duct 3 flows to the intake air in the intake duct 4 charge.

The bypass channel 30 who the turbine 500 bypasses, and a wastegate valve 31 that the bypass channel 30 opens and closes, are in the middle of the exhaust duct 3 provided. An opening degree of the wastegate valve 31 is through the ECU 8th controlled so that a flow rate of the exhaust gas through the turbine 500 flows, is adjusted and a boost pressure of the intake air by the compressor 501 is charged, is adjusted.

The intercooler 6 is in the intake duct 4 on a downstream side with respect to the compressor housing 51 placed. A coolant that the internal combustion engine 1 to be supplied, circulates within the charge air cooler. This causes heat exchange between the coolant through the charge air cooler 6 circulates, and the air flowing through the intercooler 6 passes, executed so that the intake air is cooled.

The coolant path 40 is a path along which the coolant flows between the intercooler 6 and a cooler 44 by an electric pump 42 circulated. The coolant that receives heat in the charge air cooler undergoes heat exchange with outside air in the cooler 44 and is cooled. A speed of the electric pump 42 is through the ECU 8th controlled so that a flow rate of the coolant by the electric pump 42 is transported, is thereby adjusted.

An intake air temperature sensor 16 , which is a temperature of the intake air generated by the intercooler 6 is cooled, detected, is on the downstream side with respect to the intercooler 6 provided.

In the exhaust duct 3 is the catalyst on the downstream side with respect to the turbine 500 provided. The catalyst 20 is a storage reduction type (NOx storage reduction catalyst: NSR catalyst) in which a NOx storage material such as an alkali metal is added to a three-way catalyst on which a noble metal such as platinum (Pt) is supported. The catalyst 20 stores NOx in the exhaust gas when an air-fuel ratio of the exhaust gas is leaner than a stoichiometric air-fuel ratio. The catalyst 20 reduces the NOx so stored to N ₂ when the air-fuel ratio is rich. Exhaust gas temperature sensors 13 . 14 that detect a temperature of the exhaust gas are in front of and behind the catalytic converter 20 provided.

The ECU 8th comprises a central processing unit (CPU), a read-only memory (ROM) and a random access memory (RAM). The ECU 8th executes the below-mentioned target value setting control based on information from sensors, information stored in advance in the ROM, and the like according to a control program stored in advance in the ROM.

The ECU 8th controls an operating state of the internal combustion engine 1 based on output signals from various sensors, such as a crank angle sensor 9 , an air flow meter 12 , the Exhaust gas temperature sensors 13 . 14 , the intake air temperature sensor 16 , an accelerator opening sensor 17 , an outside air temperature sensor 18 and an outside air humidity sensor 19 ,

The crank angle sensor 9 detects an angle of rotation of a crankshaft of the internal combustion engine 1 , The air flow meter 12 includes an amount of intake air entering the intake duct 4 is recorded. The exhaust gas temperature sensors 13 . 14 are on an upstream side and a downstream side of the catalyst 20 each placed to capture temperatures of the exhaust gas before and after the exhaust gas through the catalyst 20 passes.

The accelerator opening sensor 17 detects an opening degree of an accelerator pedal that is operated by a driver. For example, the ECU calculates 8th a target fuel injection amount, which is a target value of a fuel injection amount, based on a detection value of the accelerator opening sensor 17 , The outside air temperature sensor 18 detects a temperature of the outside air. The outside air humidity sensor 19 captures moisture in the outside air. The outside air temperature sensor 18 and the outside air humidity sensor 19 are an example of a temperature humidity sensor that detects an outside air temperature and an outside air humidity.

The intake air temperature sensor 16 is near an outlet of the intercooler 6 placed to detect a temperature of the intake air by the intercooler 6 is cooled. The intake air temperature sensor 16 is an example of a sensor that detects a parameter value that correlates with a temperature of the intake air generated by the charge air cooler 6 is cooled.

As described above, the ECU acquires 8th a detection value of the intake air temperature sensor 16 and controls the speed of the electric pump 42 off so that the acquired value of the intake air temperature sensor 16 reached a setpoint. The speed of the electric pump 42 is controlled to increase as the intake air temperature set point becomes lower. A plurality of setpoints are calculated as the target value of the intake air temperature based on a plurality of viewpoints, and a higher value is set among the target values calculated so as a final target value. The ECU 8th FIG. 10 is an example of a control section that regulates the speed of the electric pump 42 executes so that the temperature value reaches the setpoint. Details are described below.

Next, an operating mode of the internal combustion engine 1 described by the ECU 8th is controlled. The ECU 8th changes the operating mode of the internal combustion engine 1 between a normal mode and a NOx reduction mode. In the normal operating mode, combustion occurs at an air-fuel ratio that corresponds to an operating state that occurs in the internal combustion engine 1 is requested based on a viewpoint of ensuring an output of the internal combustion engine 1 and an improvement in fuel efficiency. For example, in the normal mode at the time of a light load, the combustion is carried out at a lean air-fuel ratio that is larger than a stoichiometric air-fuel ratio. For example, in the normal mode, at the time of idling, low speed, high speed, or heavy load, the combustion is carried out at a rich air-fuel ratio that is smaller than the stoichiometric air-fuel ratio.

In the NOx reduction mode, the catalytic converter 20 to regenerate by the NOx that is in the catalyst 20 is stored, the combustion is carried out by changing the air-fuel ratio to a rich side suitable for reducing NOx. That is, even in the case of the same engine speed and the same accelerator opening degree, the air-fuel ratio in the NOx reduction mode is set to a richer side than that in the normal mode. For example, an exhaust amount of NOx is calculated based on a fuel injection amount. Then, the change from the normal mode to the NOx reduction type is carried out when an integrated value of the discharge amount reaches a predetermined value. Further, the change from the NOx reduction mode to the normal mode is carried out when the NOx reduction mode is continued for a predetermined time, for example.

Next, setting control of a target value of intake air temperature by the ECU 8th is to be carried out. 2 FIG. 14 is a flowchart illustrating an example of the intake air temperature setpoint control by the ECU 8th is to be carried out.

First obtained or procured in step S1 the ECU 8th an engine speed of the internal combustion engine 1 and the accelerator opening degree used for step processing S3 . S5 . S7 (described below) can be used. The Engine speed and the accelerator opening degree are determined based on respective output values from the crank angle sensor 9 and the accelerator opening sensor 17 obtained.

The ECU follows 8th a first target value Tl calculation processing for calculating a first target value T1 for the target intake air temperature based on the engine speed and accelerator opening degree thus detected from ( S3 ). The first setpoint T1 is a target value based on the viewpoint of ensuring the output of the internal combustion engine 1 and prevention of emission deterioration is calculated when the mode is controlled to the normal mode. Processing according to step S3 is an example of processing for calculating the first target value T1 for a target value of a parameter value in a case where the mode is not the NOx reduction mode, based on an engine speed and a target fuel injection amount to be set when the mode is not the NOx reduction mode. Details are described below.

The ECU follows 8th a second setpoint T2 Calculation processing for calculating a second setpoint T2 for the setpoint of the intake air temperature (step S5 ). The second setpoint T2 is a target value based on the viewpoint of reducing NOx of the catalyst 20 is calculated when the operating mode is controlled to the NOx reducing mode. Processing according to step S5 is an example of processing for calculating the second target value T2 for the target value when the mode is the NOx reduction mode, based on the engine speed and a target fuel injection amount to be set when the mode is the NOx reduction mode, the second target value T2 is calculated as a value greater than the first setpoint T1 that is calculated under the same conditions of engine speed and target fuel injection amount. Details are described below.

The ECU follows 8th a third setpoint T3 Calculation processing for calculating a third setpoint T3 for the setpoint of the intake air temperature from ( S7 ). The third setpoint T3 is a target value based on the viewpoint of limiting condensed water generation in the charge air cooler 6 is calculated. Processing according to step S7 is an example of processing for calculating a third target value T3 based on the engine speed, a target fuel injection amount to be set in a certain mode, and a detected outside air temperature and a detected outside humidity. The third setpoint T3 is a set point that is to be set so that a temperature of the intake air that is generated by the charge air cooler 6 cooled, exceeds a condensation temperature. Details are described below. It should be noted that the processing according to the steps S3 . S5 . S7 can be executed in any order.

Then the ECU determines 8th whether the operating mode of the internal combustion engine 1 is the NOx reduction mode at the present moment or not ( S9 ). Processing according to step S9 FIG. 14 is an example of processing for determining whether the operating mode of the internal combustion engine 1 the NOx reduction mode is or not the air-fuel ratio of the internal combustion engine 1 is changed to the rich side to reduce the NOx contained in the catalyst 20 is saved.

In a case where the mode is not the NOx reduction mode, that is, in a case of the normal mode, the ECU determines 8th , if T1 > T3 is fulfilled or not (step S11a ). In the case of an affirmative determination, the ECU issues 8th the first setpoint T1 as a final setpoint (step S13a ). In the event of a negative determination, the ECU issues 8th the third setpoint T3 as the final setpoint (step S13b ). That is, a higher value from the first setpoint T1 and the third setpoint T3 is set as the final setpoint.

In the case of an affirmative determination in step S9 That is, in a case where the mode is the NOx reduction mode, the ECU determines 8th , if T2 > T3 is fulfilled or not (step S11b ). In the case of an affirmative determination, the second setpoint becomes T2 set as the final set point (step S13c ). In the event of a negative determination, the ECU issues 8th the third setpoint T3 as the final setpoint (step S13b ). That is, a higher value from the second setpoint T2 and the third setpoint T3 is set as the final setpoint. The processing according to the steps S13a . S13b . S13c are an example of processing for setting a higher value from the first target value T1 and the third setpoint T3 than the final setpoint when it is determined that the mode is not the NOx reduction mode and setting a higher value from the second setpoint T2 and the third setpoint T3 than the final target value when it is determined that the mode is the NOx reduction mode.

As described above, a higher value becomes the first target value T1 and the third setpoint T3 or the second setpoint T2 and the third setpoint T3 as the target value taking into account the operating mode of the internal combustion engine 1 set. A regulation is made with the speed of the electric pump 42 executed in order to reach the setpoint that is set in this way. By doing so, for example, in a case where the mode is the normal mode, the intake air temperature can be controlled to an intake air temperature suitable for the normal mode, more specifically, an intake air temperature necessary for ensuring the output of the internal combustion engine 1 and prevention of deterioration of emission is appropriate within a range where there is no condensed water in the charge air cooler 6 is produced. Further, in the NOx reduction mode, the air temperature can be changed to an intake air temperature suitable for reducing the NOx that is in the catalyst 20 is stored, can be controlled within a range in which no condensed water in the intercooler 6 is produced.

It should be noted that the processing according to the steps S3 . S5 . S7 regardless of the determination result in step S9 run to all from the first setpoint T1 up to the third setpoint T3 to calculate. For example, even if the mode is the normal mode at the present moment, the second target value becomes T2 Assuming a case where the mode is the NOx reduction mode at the engine speed of the internal combustion engine 1 and the accelerator opening degree which is in step S1 can be obtained. Similarly, even if the mode is the NOx reduction mode at the present moment, the first target value becomes T1 Assuming a case where the mode is the normal mode at the engine speed of the internal combustion engine 1 and the accelerator opening degree which is in step S1 can be obtained.

A reason for calculating everything from the first setpoint T1 up to the third setpoint T3 regardless of the current operating condition is described below. As the mode is changed, the fuel injection amount is changed to gradually reach a target value that corresponds to the mode after the change, so driveability is not so affected. For this reason, even during the mode change, if the target value corresponding to the mode after the mode change is completed is calculated in advance, the processing according to step is possible S11a or S11b Execute immediately after the change of the mode of operation is completed, thereby making it possible to set an optimal target value at an early stage.

Next, the first target value T1 calculation processing will be described. 3A shows a flowchart showing an example of the first setpoint T1 - Calculation step illustrated. The ECU 8th calculates a target fuel injection amount to be set in the normal mode based on the engine speed and the accelerator opening degree in step S1 can be obtained (step S21 ). Processing according to step S21 FIG. 10 is an example of processing for calculating the target fuel injection amount of the internal combustion engine 1 ,

More specifically, the target fuel injection amount, which is a target value of the fuel injection amount, is calculated based on a map or a calculation formula in the normal mode according to the engine speed and the accelerator opening degree. The target fuel injection amount that is set in the normal mode is a fuel injection amount that corresponds to the engine speed and the accelerator opening degree obtained to realize combustion at an air-fuel ratio that corresponds to an operating condition that corresponds to the internal combustion engine 1 is requested. The map or the calculation formula is stored in advance in the ROM of the ECU 8th saved.

The ECU then calculates 8th the first setpoint T1 based on the engine speed in step S1 is obtained, and the calculated target fuel injection amount in the normal mode (step S23 ).

3B shows an example of a map that shows a target temperature as the first target value T1 according to the engine speed and the target fuel injection amount set in the normal mode. The map prescribes an intake air temperature that is obtained in advance through an experiment so as not to deteriorate an exhaust gas emission during the output of the internal combustion engine 1 is ensured in a case where the mode is the normal mode. The map is stored in advance in the ROM of the ECU 8th saved. It should be noted that the calculation of the first setpoint T1 is not limited to such an image or to such a characteristic map, but can be calculated by a calculation formula which includes the engine speed and the Target fuel injection quantity used, which are set in the normal operating mode.

As described above, even if the mode is the NOx reduction mode at the current time, the first target value becomes T1 calculated on the basis of the map or the map or the calculation formula used in the normal operating mode.

Next, the second setpoint T2 - Calculation processing described. 4A shows a flowchart showing an example of the second set point T2 - Calculation step illustrated. The ECU 8th calculates a target fuel injection amount to be set in the NOx reduction mode based on the engine speed and the accelerator opening degree in step S1 can be obtained (step S31 ). Processing according to step S31 FIG. 10 is an example of processing for calculating the target fuel injection amount of the internal combustion engine 1 ,

More specifically, the target fuel injection amount is calculated based on a map or a calculation formula in the NOx reduction mode according to the engine speed and the accelerator opening degree. The target fuel injection amount set in the NOx reduction mode is a fuel injection amount required to realize combustion at a rich air-fuel ratio to reduce the NOx that is in the catalyst 20 is saved. The figure or the calculation formula is stored in advance in the ROM of the ECU 8th saved.

The ECU then calculates 8th the second setpoint T2 based on the engine speed in step S1 and the target fuel injection amount set in the NOx reduction mode (step S33 ).

4B shows an image or a map that shows a target temperature as the second target value T2 according to the engine speed and the target fuel injection amount set in the NOx reduction mode. The figure prescribes an inlet air temperature, which is obtained in advance by an experiment to determine the NOx that is in the catalyst 20 stored in a case where the mode is the NOx reduction mode. The map is stored in advance in the ROM of the ECU 8th saved. It should be noted that the calculation of the second setpoint T2 is not limited to such a map or map, but can be calculated by a calculation formula that uses the engine speed and the target fuel injection amount that is set in the NOx reduction mode.

Note that, as described above, even if the mode is the normal mode at the present time, the second target value T2 is calculated based on the map or the map or the calculation formula used in the NOx reduction mode.

Note that, under the same engine speed and target fuel injection quantity conditions, the second target value T2 is set to a value that is higher than the first setpoint T1 , The reason for this is that an intake air amount in the NOx reduction mode is controlled to be smaller than that in the normal mode to realize the combustion at an air-fuel ratio on the rich side, and accordingly it is not necessary to decrease the intake air temperature.

Next, the third setpoint T3 - Calculation processing described. 5 shows a flowchart showing an example of the third setpoint T3 - Calculation step illustrated. The ECU 8th calculates a target fuel injection amount to be set in a current operating state based on an engine speed and the accelerator opening degree, both in step S1 can be obtained (S41). Processing according to step S41 FIG. 10 is an example of processing for calculating the target fuel injection amount of the internal combustion engine 1 ,

The ECU then calculates 8th a target boost pressure based on the target fuel injection amount in step S41 is calculated (step S43 ). More specifically, the target boost pressure is calculated by a map or a map or a calculation formula according to the engine speed and the target fuel injection quantity. The map or the calculation formula is stored in advance in the ROM of the ECU 8th saved.

Then the ECU gets 8th an outside air temperature and an outside air humidity based on respective detection values from the outside air temperature sensor 18 and the outside air humidity sensor 19 (Step S45 ).

Then the ECU calculates 8th the third setpoint T3 based on the target charge pressure thus calculated and the outside air temperature and humidity obtained in this way (step S47 ). More specifically, a condensation temperature is calculated in a case where the Air at the outside air temperature and outside humidity is pressurized to the target boost pressure, a value obtained by adding a predetermined margin to the condensation temperature as the third target value T3 is calculated.

6 shows an example of a map or a map that prescribes the condensation temperature corresponding to the outside air temperature and the outside air humidity at the predetermined target boost pressure. A three-dimensional map or a three-dimensional map, which prescribes a condensation temperature corresponding to an outside air temperature, an outside air humidity and a target boost pressure, is in the ROM of the ECU 8th saved. The condensation temperature is calculated to be larger when the target boost pressure is larger under the condition that the outside air temperature and outside humidity are constant. It should be noted that the calculation of the condensation temperature is not limited to such an illustration, but can be calculated using a calculation formula that uses the outside air temperature, the outside air humidity and the target boost pressure.

Next, a modification of setting control of a target value of intake air temperature by the ECU will be described 8th is to be carried out. 7 11 is a flowchart illustrating the modification of the setting control of the target intake air temperature by the ECU 8th is to be carried out. Note that the same part as in the flowchart in FIG 2 has the same reference numeral to omit redundant description.

The ECU 8th first calculates a third setpoint T3 after execution, processing according to step S1 (Step S7 ). The ECU follows 8th processing according to step S9 out. In case of a negative determination in step S9 the ECU calculates 8th a first setpoint T1 (Step S10a ) and carries out processing according to step Sla and corresponding subsequent steps. In the case of an affirmative determination in step S9 the ECU calculates 8th a second setpoint T2 (Step S10b ) and carries out processing according to step S11b and corresponding subsequent steps.

As such, the calculation of the first setpoint T1 not executed when it is determined that an operation mode is NOx reduction mode. Likewise, the calculation of the second setpoint T2 not executed when it is determined that the mode is a normal mode. As such, the ECU 8th not always three setpoints T1 . T2 . T3 calculate, whereby a processing load of the ECU 8th is reduced.

The embodiment according to the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the present invention described in the claims.

In the above-described embodiment and the modification, the intake air temperature becomes near the outlet of the charge air cooler 6 used as a parameter value that correlates with the temperature of the intake air generated by the charge air cooler 6 is cooled, but the present invention is not limited to this. For example, a temperature of the coolant in the vicinity of a coolant inlet of the charge air cooler 6 or a temperature of the coolant in the vicinity of an outlet of the cooler 44 be used as the parameter value. The reason for this is that since the temperatures of the coolant are lower at these positions, the temperature of the intake air through the intercooler 6 is cooled, is also lower, and thus they are correlated with one another. In this case, it is necessary to provide a sensor that detects the temperature of the coolant in the vicinity of the coolant inlet of the charge air cooler 6 or the radiator outlet 44 detected.

In the above-described embodiment and the modification, the target value is calculated based on the engine speed and the target fuel injection amount, but the target value may additionally be calculated based on at least one parameter from an EGR rate and the outside air temperature, for example. The reason for this is that when the EGR rate is higher, an amount of fresh air to be supplied to the internal combustion engine decreases, so that a temperature of the fresh air may be low. Furthermore, the reason for this is also that when the outside air temperature is lower, an intake air amount is larger, so that the target value of the intake air temperature may be low.

In the above-described embodiment and the modification, the first target value T1 or the second setpoint T2 is calculated from the engine speed and the target fuel injection amount, but the present invention is not limited to this. For example, the target boost pressure can be calculated from the target fuel injection quantity by reference to an image or a map or a calculation formula, around the first target value T1 or the second setpoint T2 with reference to an image or a map or a calculation formula based on the target boost pressure. Furthermore, at the time of calculating the first target value T1 or the second setpoint T2 a target value calculated based on the engine speed and the target fuel injection amount based on the outside air temperature or a temperature of a coolant for cooling the internal combustion engine 1 for example corrected to a final set point T1 or T2 to calculate.

Claims (4)

Control device for an internal combustion engine (1), the internal combustion engine (1) comprising: a charge air cooler (6) configured to cool an intake air to be supplied to the internal combustion engine (1) by heat exchange with a coolant, an electric pump (42) configured to adjust a flow rate of the coolant circulating through the charge air cooler (6), an intake air temperature sensor (16) configured to detect a parameter value correlated with a temperature of the intake air cooled by the charge air cooler (6), a catalyst (20) configured to store and reduce NOx in an exhaust gas of the internal combustion engine (1), and a temperature humidity sensor (18, 19) configured to detect an outside air temperature and an outside air humidity, the control device being characterized by an electronic control unit (8) which is configured: to obtain an engine speed of the internal combustion engine (1); calculate a target fuel injection amount of the internal combustion engine (1); determine whether or not an operating mode of the internal combustion engine (1) is a NOx reduction mode, the NOx reduction mode being a mode in which an air-fuel ratio of the internal combustion engine (1) is changed to a rich side to do so Reduce NOx stored in the catalyst (20); calculate a first setpoint (T1) for a setpoint of the parameter value when the mode is not the NOx reduction mode, the first setpoint being calculated based on the engine speed and the target fuel injection amount to be set when the mode is not the NOx Reduced mode is; calculate a second target value (T2) for the target value when the mode is the NOx reduction mode, the second target value (T2) being calculated based on the engine speed and the target fuel injection amount to be set when the mode is the NOx reduction mode wherein the second target value (T2) is a value greater than the first target value (T1) calculated under the same engine speed and target fuel injection quantity conditions; calculate a third setpoint (T3) for the setpoint based on the engine speed, the target fuel injection amount to be set in the particular mode, and the detected outside air temperature and outside humidity, the third setpoint (T3) being a setpoint at which the temperature the intake air cooled by the charge air cooler (6) is higher than a condensation temperature; setting a higher value from the first target value (T1) and the third target value (T3) than a final target value if the electronic control unit (8) determines that the operating mode is not the NOx reduction mode; set a higher value of the second target value (T2) and the third target value (T3) than the final target value when the electronic control unit (8) determines that the operating mode is the NOx reduction mode; and perform a regulation at a speed of the electric pump (42) so that the parameter value reaches the set final setpoint. Control device after Claim 1 , wherein the electronic control unit (8) is configured to calculate the first setpoint (T1), the second setpoint (T2) and the third setpoint (T3) independently of a determination result of the operating mode. Control device after Claim 1 , wherein: the electronic control unit (8) is configured not to calculate the first target value (T1) when the electronic control unit (8) determines that the operating mode is the NOx reduction mode; and the electronic control unit (8) is configured not to calculate the second target value (T2) if the electronic control unit (8) determines that the operating mode is not the NOx reduction mode. A control method for an internal combustion engine (1), the internal combustion engine (1) having an intercooler (6) configured to cool an intake air to be supplied to the internal combustion engine (1) by heat exchange with a coolant, an electric pump (42 ), which is configured to adjust a flow rate of the coolant circulating through the charge air cooler (6), an intake air temperature sensor (16) configured to sense a parameter value correlated to a temperature of the intake air cooled by the charge air cooler (6); a catalyst (20) configured to NOx in an exhaust gas Storing and reducing an internal combustion engine (1) and a temperature humidity sensor (18, 19) configured to detect an outside air temperature and an outside air humidity, the control method being characterized by: calculating a target fuel injection amount of the internal combustion engine (1); determining whether or not an operating mode of the internal combustion engine (1) is a NOx reduction mode, the NOx reduction mode being a mode in which an air-fuel ratio of the internal combustion engine (1) is changed to a rich side to do so Reduce NOx stored in the catalyst (20); calculating a first setpoint (T1) for a setpoint of the parameter value when the mode is not the NOx reduction mode, the first setpoint based on an engine speed of the internal combustion engine (1) and the target fuel injection amount to be set when the mode is not the NOx reduction mode is calculated; calculating a second target value (T2) for the target value when the mode is the NOx reduction mode, the second target value being calculated based on the engine speed and the target fuel injection amount to be set when the mode is the NOx reduction mode, wherein the second target value (T2) is a value that is greater than the first target value (T1) that is calculated under the same conditions of the engine speed and the target fuel injection quantity; calculating a third target value (T3) for the target value based on the engine speed, the target fuel injection amount to be set in the particular mode, and the detected outside air temperature and outside humidity, the third target value (T3) being a target value at which the temperature the intake air cooled by the charge air cooler (6) is higher than a condensation temperature; setting a higher value of the first target value (T1) and the third target value (T3) than the final target value if the operating mode is not the NOx reduction mode; setting a higher value of the second target value (T2) and the third target value (T3) than the final target value when the operating mode is the NOx reduction mode; and performing control on the speed of the electric pump (42) so that the parameter value becomes the set final target value.

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