JP2015059526A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of performing control in accordance with a change in compressor efficiency.SOLUTION: A control device 50 controls an internal combustion engine 10 which has a turbocharger 20. The control device 50 calculates: reference compressor efficiency; and actual compressor efficiency using measurement values detected by an air flow meter 51, an atmospheric temperature sensor 52, an upstream side intake pressure sensor 53, a downstream side intake pressure sensor 54 and an intake temperature sensor 55 installed on an intake passage 12. Then, the control device 50 increases an amount of a pilot injection as a difference obtained by subtracting the actual compressor efficiency from the reference compressor efficiency gets larger.

Description

  The present invention relates to a control device for an internal combustion engine that controls an internal combustion engine equipped with a turbocharger.

  Patent Document 1 discloses a failure diagnosis apparatus that diagnoses a failure of an internal combustion engine equipped with a turbocharger. In this failure diagnosis apparatus, a failure of an internal combustion engine equipped with a turbocharger is diagnosed by comparing a value estimated by model calculation with an actual measurement value detected by a sensor. For example, the temperature and pressure of the air downstream of the turbocharger in the intake passage is estimated by model calculation, and abnormality is determined when the deviation between the estimated value and the actual value detected by the sensor is not within the normal range To do.

JP 2005-155384 A

  By the way, in Patent Document 1, the control of the internal combustion engine when an abnormality occurs and the control of the internal combustion engine in a process in which the efficiency of the compressor gradually decreases until the abnormality is determined are considered. Absent. Therefore, for example, in the process in which the efficiency of the compressor gradually decreases until an abnormality is determined, even if the engine is not properly charged, the internal combustion engine is not considered. Will drive.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for an internal combustion engine capable of performing control according to a change in compressor efficiency.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
An internal combustion engine control apparatus for solving the above problems is an internal combustion engine control apparatus for controlling an internal combustion engine equipped with a turbocharger, which is detected by means for calculating a reference compressor efficiency and a sensor provided in an intake passage. Means for calculating the actual compressor efficiency using the measured value. The control device increases the pilot injection amount as the difference obtained by subtracting the actual compressor efficiency value from the reference compressor efficiency value increases.

  When the compressor efficiency of the turbocharger changes, the state of combustion that occurs in the combustion chamber also changes. For example, if the compressor efficiency decreases, the amount of air introduced into the combustion chamber decreases and the pressure also decreases. Therefore, the temperature in the combustion chamber cannot be sufficiently increased by the main injection, and the combustion is unstable. There is a risk of becoming.

  In this regard, according to the above configuration, the compressor efficiency is reduced, and the pilot injection amount is increased as the difference obtained by subtracting the actual compressor efficiency value from the reference compressor efficiency value increases. Therefore, it is possible to increase the pilot injection amount and promote the temperature rise in the combustion chamber. As a result, even when the compressor efficiency is lowered, the temperature in the combustion chamber can be sufficiently increased by the main injection, and control according to the change in the compressor efficiency can be performed. .

The schematic diagram which shows the relationship between the control apparatus as one Embodiment of the control apparatus of an internal combustion engine, and the internal combustion engine which is a control object of the control apparatus. The flowchart which shows the flow of the failure diagnosis process which the control apparatus concerning the embodiment performs. The flowchart which shows the flow of the injection correction process which the control apparatus concerning the embodiment performs. The graph which shows the relationship between the difference D (eta) c which subtracted the value of actual compressor efficiency (eta) c from the value of reference | standard compressor efficiency (eta) cb, and the pilot injection correction amount plc. The graph which shows the relationship between the excess amount (DELTA) pl and the injection timing correction amount injc.

Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to FIGS.
As shown in FIG. 1, an intake passage 12 and an exhaust passage 13 are connected to the combustion chamber 11 of the internal combustion engine 10. The internal combustion engine 10 is a diesel engine and includes an in-cylinder injection valve 14 that directly injects fuel into the combustion chamber 11.

  The internal combustion engine 10 is provided with a turbocharger 20. The turbocharger 20 includes a turbine wheel 21 that is rotated by the force of exhaust gas flowing in the exhaust passage 13, and a compressor wheel 22 that rotates together with the turbine wheel 21 and sends the air in the intake passage 12 toward the combustion chamber 11. Yes. As a result, in the internal combustion engine 10, the compressor wheel 22 is rotated by the exhaust force, and the air introduced into the intake passage 12 from the air cleaner 15 is pressurized by the turbocharger 20 and sent into the combustion chamber 11.

  As shown in FIG. 1, an air flow meter 51, an atmospheric temperature sensor 52, and an upstream intake pressure sensor 53 are provided at a portion upstream of the compressor wheel 22 in the intake passage 12. The air flow meter 51 detects the amount of air taken through the air cleaner 15 and flowing in the intake passage 12, that is, the intake air amount Ga. The atmospheric temperature sensor 52 detects the temperature T1 of the air that has passed through the air cleaner 15 and is taken into the intake passage 12. That is, the temperature T1 detected by the atmospheric temperature sensor 52 is the temperature of the air before being compressed by the turbocharger 20. Further, the upstream side intake pressure sensor 53 detects the pressure P <b> 1 in the upstream side of the compressor wheel 22 in the intake passage 12. That is, the pressure P1 detected by the upstream side intake pressure sensor 53 is the pressure of air before being compressed by the turbocharger 20.

  On the other hand, a downstream side intake pressure sensor 54 and an intake temperature sensor 55 are provided in a portion of the intake passage 12 on the downstream side of the compressor wheel 22. The downstream intake pressure sensor 54 detects the pressure P3 in the portion of the intake passage 12 downstream of the compressor wheel 22. That is, the pressure P3 detected by the downstream side intake pressure sensor 54 is the pressure of the air after being compressed by the turbocharger 20. The intake air temperature sensor 55 detects the temperature T3 of the air that passes through the compressor of the turbocharger 20 and is introduced into the combustion chamber 11. That is, the temperature T3 detected by the intake air temperature sensor 55 is the temperature of the air after being compressed by the turbocharger 20.

  All of these sensors are electrically connected to a control device 50 that controls the internal combustion engine 10. In addition to these sensors, the control device 50 includes an accelerator position sensor 56 that detects the amount of operation of the accelerator pedal, a crank angle sensor 57 that detects the rotation angle of the crankshaft, and a water temperature sensor 58 that detects the temperature of the cooling water. Etc. are also electrically connected. Further, a turbine rotational speed sensor 59 that detects a turbine rotational speed Nt that is a rotational speed of the turbine wheel 21 and the compressor wheel 22 of the turbocharger 20 is also electrically connected to the control device 50.

  The control device 50 controls the internal combustion engine 10 based on signals output from these various sensors. For example, the control device 50 calculates the engine rotational speed NE that is the rotational speed of the crankshaft based on the crank angle detected by the crank angle sensor 57. Based on the accelerator pedal operation amount detected by the accelerator position sensor 56 and the engine rotational speed NE, the fuel injection amount to be injected from the in-cylinder injection valve 14 is calculated, and an amount of fuel corresponding to the calculated fuel injection amount is calculated. The in-cylinder injection valve 14 is controlled to inject fuel. In the internal combustion engine 10 of the present embodiment, pilot injection is performed prior to the main injection that mainly contributes to the generation of torque in order to perform fuel injection in one combustion stroke in a plurality of times and generate good combustion. To implement. That is, the control device 50 performs fuel injection control, which is control of the injection amount and injection timing of pilot injection and main injection.

  The control device 50 also performs failure diagnosis processing for diagnosing whether a failure has occurred in each part of the internal combustion engine 10. An example of the failure diagnosis process performed by the control device 50 will be described with reference to FIG. This failure diagnosis process is repeatedly executed at a predetermined control cycle when the internal combustion engine 10 is in operation.

  As shown in FIG. 2, when the failure diagnosis process is started, the control device 50 acquires the detection value of each sensor in step S100. Specifically, the control device 50 detects the pressure P1 detected by the upstream intake pressure sensor 53, the pressure P3 detected by the downstream intake pressure sensor 54, the temperature T1 detected by the atmospheric temperature sensor 52, and the intake air temperature sensor. The temperature T3 detected by 55, the intake air amount Ga detected by the air flow meter 51, and the turbine rotational speed Nt detected by the turbine rotational speed sensor 59 are read.

  Next, in step S110, the control device 50 is a downstream side that is an estimated value of the temperature of air after being compressed by the turbocharger 20 based on the temperature T1, the pressure P1, the pressure P3, and the intake air amount Ga read in step S100. A temperature estimated value T3est is calculated. That is, here, the intake air amount Ga which is the amount of air flowing in the intake passage 12, the temperature T1 and pressure P1 of the air before being compressed by the turbocharger 20, and the air after being compressed by the turbocharger 20 Based on the relationship with the pressure P3, the downstream temperature estimated value T3est is calculated. For example, the control device 50 sets the value of the temperature T1, the pressure P1, the pressure P3, and the intake air amount Ga to a function f (T1, P1, P3, Ga) having the temperature T1, the pressure P1, the pressure P3, and the intake air amount Ga as variables. Is input to calculate the downstream temperature estimated value T3est. The function f (T1, P1, P3, Ga) is set so that the temperature T3 can be estimated from the temperature T1, the pressure P1, the pressure P3, and the intake air amount Ga based on the results of experiments performed in advance.

  When the downstream temperature estimated value T3est is thus calculated, the control device 50 calculates a deviation ΔT3 between the temperature T3 actually detected by the intake air temperature sensor 55 and the downstream temperature estimated value T3est in step S120. Here, the absolute value of the difference obtained by subtracting the downstream temperature estimated value T3est from the value of the temperature T3 detected by the intake air temperature sensor 55 is calculated as the deviation ΔT3.

  Next, in step S130, control device 50 determines whether or not deviation ΔT3 is less than determination value Ta. The determination value Ta is a threshold value for determining whether or not the intake air temperature sensor 55 has failed based on the magnitude of the deviation ΔT3. The magnitude of the determination value Ta is set based on the result of an experiment or the like performed in advance so that it can be appropriately determined that a failure has occurred when the deviation ΔT3 is greater than or equal to the determination value Ta.

  If it is determined in step S130 that the deviation ΔT3 is greater than or equal to the determination value Ta (step S130: NO), the process proceeds to step S135, and the control device 50 determines that the intake air temperature sensor 55 has failed. . Based on the determination result, the control device 50 lights, for example, a warning lamp for notifying that the intake air temperature sensor 55 has failed, or stores information indicating that the intake air temperature sensor 55 has failed in the memory. Or remember. When it is determined that the intake air temperature sensor 55 has failed in this way, the control device 50 temporarily ends this process.

  On the other hand, when it is determined in step S130 that the deviation ΔT3 is less than the determination value Ta (step S130: YES), the process proceeds to step S140, and the control device 50 determines that the intake air temperature sensor 55 is normal. To do. Here, the control device 50 stores in the memory information indicating that the intake air temperature sensor 55 is normal. Based on the determination result, the warning lamp that has been turned on is turned off, or the information indicating the state of the intake air temperature sensor 55 stored in the memory is updated to information indicating normality. It may be. Further, when it is determined that it is normal here, the process may proceed to the next step S150 without performing anything.

  In next step S150, control device 50 calculates compressor efficiency ηc based on temperature T1, temperature T3, pressure P1, and pressure P3 read in step S100. That is, here, based on the relationship between the temperature T1 and pressure P1 of the air before being compressed by the turbocharger 20 and the temperature T3 and pressure P3 of the air after being compressed by the turbocharger 20, the excess by the turbocharger 20 is determined. Compressor efficiency ηc indicating supply efficiency is calculated. The controller 50 inputs the values of the temperature T1, the temperature T3, the pressure P1, and the pressure P3 into the function g (T1, T3, P1, P3) having the temperature T1, the temperature T3, the pressure P1, and the pressure P3 as variables. ηc is calculated. The function g (T1, T3, P1, P3) is set so that the compressor efficiency ηc can be calculated from the temperature T1, the temperature T3, the pressure P1, and the pressure P3 based on the results of experiments performed in advance.

  When the actual compressor efficiency ηc is calculated based on the measurement value measured by the sensor in this way, the control device 50 calculates the reference compressor efficiency ηcb in step S160. The reference compressor efficiency ηcb is a value indicating the compressor efficiency that should be obtained when the turbocharger 20 is equal to the reference state, and is calculated based on the turbine rotational speed Nt. For example, if the relationship between the turbine rotational speed Nt and the compressor efficiency in the internal combustion engine 10 equipped with a new turbocharger 20 that is not deteriorated at all is measured, the turbine rotational speed Nt and the reference compressor efficiency are determined from the measurement result. An arithmetic map showing the relationship with ηcb can be created. By using such a calculation map, the control device 50 calculates the compressor efficiency that should be obtained by the turbocharger 20 in the new state based on the turbine rotational speed Nt detected by the turbine rotational speed sensor 59, and the reference compressor efficiency ηcb. Can be calculated as

  When the state of the turbocharger 20 changes, the compressor efficiency ηc deviates from the reference compressor efficiency ηcb. For example, if deposits are accumulated in the scroll passage of the turbocharger 20 or the blades of the compressor wheel 22 are deformed, the ability to compress and send out air is reduced even if the turbine rotational speed Nt is the same. Therefore, in this case, the compressor efficiency ηc is lower than the reference compressor efficiency ηcb.

  When the reference compressor efficiency ηcb is calculated in step S160, the controller 50 calculates the compressor efficiency deviation Δηc in step S170. This deviation Δηc is a value indicating the magnitude of deviation of the compressor efficiency ηc from the reference compressor efficiency ηcb. Here, the absolute value of the difference obtained by subtracting the value of the compressor efficiency ηc from the value of the reference compressor efficiency ηcb is calculated as the deviation Δηc.

  When the deviation Δηc is calculated in step S170, the control device 50 determines in step S180 whether or not the deviation Δηc is less than the determination value Tb. The determination value Tb is a threshold value for determining whether or not the turbocharger 20, in particular, the compressor has failed, based on the magnitude of the deviation Δηc. The magnitude of the determination value Tb is set based on a result of an experiment or the like that is performed in advance so that it can be appropriately determined that a failure has occurred when the deviation Δηc is equal to or greater than the determination value Tb.

  If it is determined in step S180 that the deviation Δηc is greater than or equal to the determination value Tb (step S180: NO), the process proceeds to step S185, and the control device 50 determines that the compressor has failed. Based on the determination result, the control device 50 lights, for example, a warning lamp for notifying that the compressor has failed, or stores information indicating that the compressor has failed in the memory. When it is determined that the compressor has failed, the control device 50 once ends this process.

  On the other hand, when it is determined in step S180 that the deviation Δηc is less than the determination value Tb (step S180: YES), the process proceeds to step S190, and the control device 50 determines that the compressor is normal. Here, the control device 50 stores in the memory information indicating that the compressor is normal.

When it is determined that the compressor is normal in this way, the control device 50 once ends this process.
In step S190, based on the determination result that the compressor is normal, the warning lamp for notifying that the compressor that has been turned on is out of order is turned off, or the state of the compressor stored in the memory is changed. The information to be displayed may be updated to information indicating normality. If it is determined in step S190 that the operation is normal, the failure diagnosis process may be temporarily terminated without performing anything.

  By the way, even if the compressor efficiency ηc does not deviate from the reference compressor efficiency ηcb so that the compressor failure is determined, the supercharging efficiency is not a little when the compressor efficiency ηc deviates from the reference compressor efficiency ηcb. It will be changing. Therefore, it is preferable to perform engine control in accordance with the change in compressor efficiency ηc when performing appropriate engine operation. Therefore, in the control device 50 of the present embodiment, an injection correction process for correcting the pilot injection amount plf and the injection timing of the main injection is executed based on the relationship between the reference compressor efficiency ηcb and the compressor efficiency ηc.

Next, an example of this injection correction process will be described with reference to FIGS. This injection correction process is repeatedly executed at a predetermined control cycle when the internal combustion engine 10 is in operation.
As shown in FIG. 3, when the injection correction process is started, the control device 50 reads the compressor efficiency ηc and the reference compressor efficiency ηcb in step S200. Here, the control device 50 reads the compressor efficiency ηc calculated in step S150 in the above-described failure diagnosis process and the reference compressor efficiency ηcb calculated in step S160.

  Next, in step S210, the control device 50 calculates a difference Dηc between the reference compressor efficiency ηcb and the compressor efficiency ηc. Here, the controller 50 calculates the difference Dηc by subtracting the compressor efficiency ηc from the reference compressor efficiency ηcb.

  When the difference Dηc is calculated, the process proceeds to step S220, and the control device 50 calculates the pilot injection correction amount plc. Here, the pilot injection correction amount plc is calculated based on the difference Dηc calculated in step S210. For example, the control device 50 calculates the pilot injection correction amount plc by inputting the value of the difference Dηc into a function h (Dηc) having the difference Dηc as a variable. The function h (Dηc) is a proportional function in which the pilot injection correction amount plc increases as the difference Dηc increases, as shown in FIG. When the difference Dηc is a negative value, the pilot injection correction amount plc is also a negative value.

  When the pilot injection correction amount plc is calculated in this way, the control device 50 reads the reference pilot injection amount plb in step S230. The reference pilot injection amount plb is calculated according to the operating state of the internal combustion engine 10 through the fuel injection control described above. For example, the reference pilot injection amount plb is increased or decreased according to the intake air amount Ga, the engine rotational speed NE, the temperature of air sucked into the combustion chamber 11 or the temperature of cooling water. As an example, the larger the intake air amount Ga is, the larger the amount is as the engine rotational speed NE is higher, and the higher the air temperature and the engine cooling water temperature are.

  When the reference pilot injection amount plb is read, the process proceeds to step S240, and the control device 50 calculates the pilot injection amount plf. Here, the control device 50 calculates the sum obtained by adding the pilot injection correction amount plc to the reference pilot injection amount plb as the pilot injection amount plf.

  Next, in step S250, the control device 50 determines whether or not the pilot injection amount plf is larger than the pilot injection upper limit injection amount. The pilot injection upper limit injection amount is an upper limit value of the amount of fuel that can be injected in pilot injection.

  When it is determined in step S250 that the pilot injection amount plf is larger than the pilot injection upper limit injection amount (step S250: YES), the process proceeds to step S260, and the control device 50 calculates the surplus amount Δpl. Here, the difference obtained by subtracting the pilot injection upper limit injection amount from the pilot injection amount plf is calculated as the surplus amount Δpl.

  When the surplus amount Δpl is calculated, the process proceeds to step S270, and the control device 50 calculates the injection timing correction amount injc. Here, an injection timing correction amount injc, which is a correction amount for correcting the injection timing of the main injection to the advance side, is calculated based on the surplus amount Δpl calculated in step S260. For example, the control device 50 calculates the injection timing correction amount injc by inputting the value of the surplus amount Δpl into a function j (Δpl) having the surplus amount Δpl as a variable. As shown in FIG. 5, the function j (Δpl) is a proportional function in which the injection timing correction amount injc increases as the value of the surplus amount Δpl increases. Therefore, as the surplus amount Δpl increases, the injection timing of the main injection is advanced.

  When the injection timing correction amount injc is calculated in this way, the control device 50 once ends this process. By setting the injection timing correction amount injc in this way, the injection timing of the main injection executed through the injection amount control is corrected to the advance side. Further, at this time, since the calculated pilot injection amount plf exceeds the pilot injection upper limit injection amount, the amount of fuel equal to the upper limit pilot injection upper limit injection amount is injected in the pilot injection.

  On the other hand, when it is determined in step S250 that the pilot injection amount plf is less than or equal to the pilot injection upper limit injection amount (step S250: NO), the control device 50 does not execute step S260 and step S270, The process ends. That is, in this case, the injection timing of the main injection is not corrected. In pilot injection, an amount of fuel equal to the pilot injection amount plf calculated in step S240 is injected.

Next, the effect | action of the injection correction process which the control apparatus 50 concerning this embodiment performs is demonstrated.
As the compressor efficiency ηc decreases and the difference Dηc obtained by subtracting the actual compressor efficiency ηc from the value of the reference compressor efficiency ηcb increases, the pilot injection correction amount plc increases. Will be increased.

  Further, when the pilot injection amount plf becomes larger than the pilot injection upper limit injection amount, the injection timing of the main injection is corrected to the advance side as the surplus amount Δpl increases.

According to the embodiment described above, the following effects can be obtained.
(1) The pilot injection amount plf is increased as the compressor efficiency ηc decreases and the difference Dηc increases. Thereby, since the temperature rise in the combustion chamber 11 is promoted, even if the compressor efficiency ηc is lowered, the temperature in the combustion chamber 11 can be sufficiently increased by the main injection, Control according to the change in the compressor efficiency ηc can be performed.

  (2) When the pilot injection amount plf exceeds the pilot injection upper limit injection amount, the pilot injection amount is limited, and the temperature in the combustion chamber 11 cannot be sufficiently increased by the pilot injection, resulting in an ignition delay. This may cause a deterioration in fuel consumption. On the other hand, when the pilot injection amount plf exceeds the pilot injection upper limit injection amount, the injection timing of the main injection is advanced in anticipation of the ignition delay, thereby suppressing deterioration of fuel consumption. be able to.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
Although the method of calculating the downstream side temperature estimated value T3est, the compressor efficiency ηc, the pilot injection correction amount plc, and the injection timing correction amount injc is exemplified, the calculation method of these values may be changed as appropriate. it can. For example, the calculation map may be used for calculation.

  Although the method of calculating the reference compressor efficiency ηcb based on the turbine rotational speed Nt is exemplified, the method of calculating the reference compressor efficiency ηcb is not limited to the exemplified method. For example, the reference compressor efficiency ηcb may be estimated from the fuel injection amount and the engine rotational speed NE. In addition to the turbine rotation speed Nt, the reference compressor efficiency ηcb may be calculated by referring to the temperature of the cooling water, the temperature of the air detected by the atmospheric temperature sensor 52, and the like.

  The method for calculating the compressor efficiency ηc may be any method as long as it can calculate the actual compressor efficiency based on the measured value detected by the sensor provided in the intake passage 12, and the method described in the above embodiment is used. It is not limited and can be changed appropriately.

  In the failure diagnosis process of the above embodiment, it is diagnosed whether or not the intake air temperature sensor 55 is broken before diagnosing whether or not the compressor is broken, and only when the intake air temperature sensor 55 is normal. Although the compressor failure diagnosis is performed, the failure diagnosis of the intake air temperature sensor 55 may be omitted. That is, the processing from steps S110 to S140 for failure diagnosis of the intake air temperature sensor 55 in the failure diagnosis processing flowchart shown in FIG. You may make it perform the failure diagnosis of a compressor.

-Moreover, although the example which implements both a failure diagnosis process and an injection correction process was shown, you may make it perform an injection correction process, without performing a failure diagnosis process.
In addition, when the compressor efficiency ηc is significantly reduced and a compressor failure is determined, there is a possibility that the combustion state cannot be improved even if the injection correction process is executed. Therefore, the injection correction process may be executed only until a compressor failure is determined.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Combustion chamber, 12 ... Intake passage, 13 ... Exhaust passage, 14 ... In-cylinder injection valve, 15 ... Air cleaner, 20 ... Turbocharger, 21 ... Turbine wheel, 22 ... Compressor wheel, 50 ... Control device , 51 ... Air flow meter, 52 ... Atmospheric temperature sensor, 53 ... Upstream intake pressure sensor, 54 ... Downstream intake pressure sensor, 55 ... Intake temperature sensor, 56 ... Accelerator position sensor, 57 ... Crank angle sensor, 58 ... Water temperature sensor 59 ... Turbine rotational speed sensor.

Claims (1)

An internal combustion engine control device for controlling an internal combustion engine equipped with a turbocharger,
Means for calculating the reference compressor efficiency;
Means for calculating actual compressor efficiency using measured values detected by a sensor provided in the intake passage,
The control apparatus for an internal combustion engine, characterized in that the pilot injection amount is increased as the difference obtained by subtracting the actual compressor efficiency value from the reference compressor efficiency value is larger.