JP5938955B2 - Fuel injection characteristic learning device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection characteristic learning device for an internal combustion engine that learns the operating characteristic of a fuel injection valve based on a fuel pressure in a fuel supply system.

  The internal combustion engine is provided with a fuel supply system including a supply passage for supplying fuel in a pressurized state and a fuel injection valve connected to the supply passage. In recent years, a device has been proposed in which a pressure sensor for detecting the fuel pressure inside the fuel supply system is provided, and the operating characteristics of the fuel injection valve are learned based on the fuel pressure detected by the pressure sensor ( Patent Document 1). When the fuel injection is performed, the fuel pressure in the fuel supply system temporarily decreases as the fuel injection valve starts to open and then increases as the fuel injection valve closes thereafter. In the apparatus described in Patent Document 1, the operating characteristics of the fuel injection valve are estimated and learned based on the variation of the fuel pressure inside the fuel supply system.

JP 2009-57928 A

  By the way, when learning the operating characteristics of the fuel injection valve based on the fuel pressure detected by the pressure sensor, it is possible to grasp the fuel pressure fluctuation mode in detail by shortening the fuel pressure detection interval. Therefore, it becomes possible to learn the operating characteristics of the fuel injection valve with high accuracy. However, in such a case, the calculation load of the calculation processing device at the time of execution of the process related to learning of the operating characteristics of the fuel injection valve becomes large.

  Further, if the operating characteristics of the fuel injection valve are simply estimated based on the fuel pressure fluctuation mode, for example, when the fuel pressure changes suddenly due to a change in the engine operating state, it depends on the operating state of the internal combustion engine. May have very low learning accuracy of the same operating characteristics. In order to suppress such a decrease in learning accuracy, it is conceivable to determine whether or not learning of the operation characteristics can be performed based on the engine parameter grasped by the arithmetic processing unit. In such a device, it is possible to suppress a decrease in the learning accuracy of the operation characteristics, but this results in a further concentration of calculation load in the calculation processing device. Such concentration of calculation load is not preferable because it causes a decrease in the degree of freedom in setting the calculation processing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel for an internal combustion engine that can suppress both the concentration of calculation load in the calculation processing device and the decrease in learning accuracy of the operating characteristics of the fuel injection valve. It is to provide an injection characteristic learning device.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The apparatus according to claim 1 has a pressure sensor for detecting a fuel pressure inside a fuel supply system having a fuel injection valve, and an operating characteristic of the fuel injection valve based on the fuel pressure detected by the pressure sensor. In a fuel injection characteristic learning device for an internal combustion engine that executes a learning process for learning the first processing unit, a first arithmetic processing unit that executes a determination process for determining whether or not the learning process can be executed based on an engine parameter, and the first arithmetic processing unit And a second arithmetic processing unit that executes the learning process according to the received determination result.

  According to the above apparatus, when the learning of the operating characteristics of the fuel injection valve is executed, the determination process and the learning process are executed by different arithmetic processing devices, so that the calculation load on a specific arithmetic processing device is reduced. Concentration can be suppressed. Moreover, when it is determined that the learning process cannot be performed through the determination process based on the engine parameter by the first arithmetic processing unit, the learning process by the second arithmetic processing unit is not performed, and it is determined that the learning process can be performed through the determination process. In such a case, a learning process by the second arithmetic processing unit is executed. As a result, the learning process can be prohibited from being performed when the engine is in an engine operating state where the learning accuracy of the learning process may be low enough to cause a problem. Can be suppressed.

Further device according to claim 1, wherein the second processor is determined in advance and the variation waveform to form a fluctuation waveform during the valve opening drive of the fuel injection valve in the fuel pressure detected by the pressure sensor The gist of the present invention is to execute, as the learning process, a process for learning a learning correction term based on the relationship with the obtained basic waveform.

In the apparatus according to claim 1 , since the process of forming a fluctuation waveform of the fuel pressure is executed based on the fuel pressure detected by the pressure sensor, learning is performed based on only one of the detected values of the pressure sensor. Compared with a device that executes processing, the computational load on the arithmetic processing device tends to increase when the learning processing is executed. According to the above apparatus, in such an apparatus, it is possible to suppress the concentration of the calculation load on a specific calculation processing apparatus, and thus it is possible to suppress a decrease in the degree of freedom in setting the calculation process related to the learning process and the determination process.
In the fuel injection characteristic learning apparatus as described above, when the engine parameter largely fluctuates due to a factor (disturbance) other than the opening / closing drive of the fuel injection valve, the learning accuracy of the operating characteristic of the fuel injection valve may be reduced.
Therefore, in the apparatus according to claim 2, with respect to the determination process for determining whether or not the learning process can be executed, if the operation state of the internal combustion engine determined by the engine parameter is a transient operation state, the determination to prohibit the execution of the learning process is performed. Is the gist. According to the above apparatus, when the operation state of the internal combustion engine determined by the engine parameters is a transient operation state, that is, an engine in which the amount of fluctuation of the engine parameter due to disturbance is large and the learning accuracy may be lowered to a problem. When in the driving state, the execution of the learning process is prohibited. That is, a decrease in learning accuracy can be suppressed.

  The device according to claim 3 is the fuel injection characteristic learning device for an internal combustion engine according to claim 1 or 2, wherein the internal combustion engine has a plurality of cylinders, and the fuel injection valve is provided for each cylinder of the internal combustion engine. The gist of the second arithmetic processing unit is that the learning process is executed separately for each fuel injection valve provided for each cylinder of the internal combustion engine.

  According to the apparatus of claim 3, since the learning process is executed for each of the plurality of fuel injection valves, a specific calculation process is performed in an apparatus in which the calculation load on the calculation processing apparatus tends to increase when the learning process is executed. Concentration of calculation load on the apparatus can be suppressed.

  According to a fourth aspect of the present invention, there is provided a fuel injection characteristic learning device for an internal combustion engine according to the third aspect, wherein the pressure sensor is integrally formed with each fuel injection valve provided for each cylinder. To do.

  According to the apparatus of claim 4, the fuel pressure at the portion near the injection hole of the fuel injection valve is detected as compared with the apparatus in which the fuel pressure at a position away from the fuel injection valve is detected by the pressure sensor. Can do. In addition, since it is possible to detect the fuel pressure at a position away from the fuel injection valves of the other cylinders, it is possible to suppress the influence of pressure fluctuations associated with the opening / closing operations of the fuel injection valves of the other cylinders. Therefore, it is possible to accurately detect a change in the fuel pressure inside the fuel injection valve due to the opening / closing operation of the fuel injection valve by the pressure sensor attached integrally, and based on the pressure, the operating characteristic of the fuel injection valve is high. You can learn with accuracy.

  In the learning process, when the fluctuation amount of the fuel pressure due to a factor (disturbance) other than the opening / closing drive of the fuel injection valve is large, there is a high possibility that the learning accuracy of the operating characteristic of the fuel injection valve is reduced by the learning process.

  In this regard, in the apparatus according to claim 5, the engine parameter used for the determination process includes the fuel pressure. According to such an apparatus, since the determination process is executed based on the fuel pressure, it is appropriately determined whether or not the learning process can be executed by the determination process in accordance with the magnitude of the fluctuation amount of the fuel pressure due to the disturbance. Can be executed.

1 is a schematic diagram showing a schematic configuration of a fuel injection characteristic learning device for an internal combustion engine according to an embodiment embodying the present invention. Sectional drawing which shows the cross-section of a fuel injection valve. The time chart which shows an example of a basic time waveform. The schematic diagram which shows the connection aspect of an electronic control unit and each fuel injection valve. The flowchart which shows the execution procedure of a determination process. The flowchart which shows the execution procedure of a characteristic learning control process. The timing chart which shows an example of the execution aspect of a determination process.

Hereinafter, a fuel injection characteristic learning apparatus for an internal combustion engine according to an embodiment of the present invention will be described.
As shown in FIG. 1, an intake passage 12 is connected to the cylinder 11 of the internal combustion engine 10. Air is sucked into the cylinder 11 of the internal combustion engine 10 through the intake passage 12. As the internal combustion engine 10, a diesel engine having a plurality of (four [# 1, # 2, # 3, # 4] in this embodiment) cylinders 11 is employed. The internal combustion engine 10 is provided with a direct injection type fuel injection valve 20 that directly injects fuel into the cylinder 11 for each cylinder 11 (# 1 to # 4). The fuel injected by opening the fuel injection valve 20 is ignited and burned in contact with the intake air compressed and heated in the cylinder 11 of the internal combustion engine 10. In the internal combustion engine 10, the piston 13 is pushed down by the energy generated by the combustion of fuel in the cylinder 11, and the crankshaft 14 as the engine output shaft is forcibly rotated. The combustion gas combusted in the cylinder 11 of the internal combustion engine 10 is discharged as exhaust gas into the exhaust passage 15 of the internal combustion engine 10.

  Each fuel injection valve 20 is individually connected to a common rail 34 via a branch passage 31a. The common rail 34 is connected to the fuel tank 32 through a supply passage 31b. A fuel pump 33 that pumps fuel is provided in the supply passage 31b. In the present embodiment, the fuel boosted by the pumping by the fuel pump 33 is stored in the common rail 34 and supplied to each fuel injection valve 20. In this embodiment, each fuel injection valve 20, the branch passage 31a, the supply passage 31b, the fuel pump 33, and the common rail 34 function as a fuel supply system.

  A return passage 35 is connected to each fuel injection valve 20. The return passages 35 are each connected to the fuel tank 32. A part of the fuel inside the fuel injection valve 20 is returned to the fuel tank 32 through the return passage 35.

Hereinafter, the internal structure of the fuel injection valve 20 will be described.
As shown in FIG. 2, a needle valve 22 is provided inside the housing 21 of the fuel injection valve 20. The needle valve 22 is provided in a state capable of reciprocating in the housing 21 (moving up and down in the figure). Inside the housing 21 is provided a spring 24 that constantly urges the needle valve 22 toward the injection hole 23 (the lower side in the figure). In addition, a nozzle chamber 25 is formed in the housing 21 at a position on one side (lower side in the figure) with the needle valve 22 interposed therebetween, and at a position on the other side (upper side in the figure). A pressure chamber 26 is formed.

  The nozzle chamber 25 is formed with an injection hole 23 that communicates the inside with the outside of the housing 21, and fuel is supplied from the branch passage 31 a (common rail 34) through the introduction passage 27. The pressure chamber 26 is connected to the nozzle chamber 25 and the branch passage 31a (common rail 34) via a communication passage 28. The pressure chamber 26 is connected to a return passage 35 (fuel tank 32) via a discharge passage 30.

  As the fuel injection valve 20, an electrically driven type is adopted. Specifically, a piezoelectric actuator 29 in which a piezoelectric element (for example, a piezoelectric element) that expands and contracts by input of a drive signal is provided inside the housing 21 of the fuel injection valve 20. A valve body 29 a is attached to the piezoelectric actuator 29. The valve body 29 a is provided inside the pressure chamber 26. Then, through the movement of the valve element 29 a by the operation of the piezoelectric actuator 29, one of the communication path 28 (nozzle chamber 25) and the discharge path 30 (return path 35) is selectively communicated with the pressure chamber 26. It has become.

  In the fuel injection valve 20, when a valve closing signal is input to the piezoelectric actuator 29, the piezoelectric actuator 29 contracts and the valve body 29 a moves, so that the communication path 28 and the pressure chamber 26 communicate with each other. At the same time, the communication between the return passage 35 and the pressure chamber 26 is blocked. Thereby, the nozzle chamber 25 and the pressure chamber 26 are communicated with each other in a state where the discharge of the fuel in the pressure chamber 26 to the return passage 35 (fuel tank 32) is prohibited. As a result, the pressure difference between the nozzle chamber 25 and the pressure chamber 26 becomes very small, and the needle valve 22 moves to a position where it closes the injection hole 23 by the urging force of the spring 24. Is not injected (valve closed state).

  On the other hand, when a valve opening signal is input to the piezoelectric actuator 29, the piezoelectric actuator 29 extends and the valve body 29a moves, whereby the communication between the communication passage 28 and the pressure chamber 26 is blocked. The return passage 35 and the pressure chamber 26 are in communication with each other. As a result, part of the fuel in the pressure chamber 26 is returned to the fuel tank 32 via the return passage 35 in a state in which the outflow of fuel from the nozzle chamber 25 to the pressure chamber 26 is prohibited. As a result, the pressure of the fuel in the pressure chamber 26 decreases and the pressure difference between the pressure chamber 26 and the nozzle chamber 25 increases, and the needle valve 22 moves against the biasing force of the spring 24 due to the pressure difference. In order to leave the injection hole 23, the fuel injection valve 20 is in a state where the fuel is injected (opened state) at this time.

  A pressure sensor 51 for detecting the fuel pressure PQ inside the introduction passage 27 is integrally attached to the fuel injection valve 20. For this reason, for example, the fuel in a portion near the injection hole 23 of the fuel injection valve 20 as compared with a device that detects the fuel pressure at a position away from the fuel injection valve 20 such as the fuel pressure in the common rail 34 (see FIG. 1). The pressure can be detected, and the change in the fuel pressure inside the fuel injection valve 20 accompanying the opening of the fuel injection valve 20 can be detected with high accuracy. The pressure sensor 51 includes a sensor main body 51A that outputs a signal corresponding to the fuel pressure and a memory 51B that stores a detection value of the sensor main body 51A. It is provided for every 10 cylinders 11 (# 1 to # 4).

  As shown in FIG. 1, the internal combustion engine 10 is provided with various sensors as peripheral devices for detecting an operation state. As these sensors, in addition to the pressure sensor 51, for example, an intake air amount sensor 52 for detecting the amount of air passing through the intake passage 12 (passage air amount GA), the rotational speed of the crankshaft 14 (engine rotational speed NE). ) Is provided. In addition, an accelerator sensor 54 for detecting an operation amount (accelerator operation amount ACC) of an accelerator operation member (for example, an accelerator pedal), a fuel temperature sensor 55 for detecting a fuel temperature THQ, and a coolant temperature THW are detected. A water temperature sensor 56 is also provided.

  Moreover, as a peripheral device of the internal combustion engine 10, an electronic control unit 40 configured with an arithmetic processing unit is also provided. The electronic control unit 40 takes in the output signals of various sensors and performs various calculations based on the output signals, and controls the operation of the fuel injection valve 20 (injection amount control) and the operation of the fuel pump 33 based on the calculation results. Various controls related to the operation of the internal combustion engine 10 such as control (injection pressure control) are executed. The electronic control unit 40 includes two arithmetic processing devices such as a sub arithmetic processing device 41 and a main arithmetic processing device 42. The functions of the sub arithmetic processing unit 41 and the main arithmetic processing unit 42 will be described in detail later.

  In the present embodiment, the injection amount control is executed as follows. That is, first, an injection pattern is selected on the basis of values (so-called engine parameters) correlated with the operating state of the internal combustion engine 10 such as the passage air amount GA, the engine rotational speed NE, and the accelerator operation amount ACC. Various control target values for each injection are calculated. In the present embodiment, a plurality of injection patterns that combine main injection, pilot injection, after-injection, and the like are set in advance, and one of these injection patterns is selected when executing injection amount control. Further, as various control target values, a target value (target injection amount) for the fuel injection amount of each injection such as main injection, pilot injection, and after injection, a target value (target injection timing) for the injection timing of main injection, An interval between the main injection and the pilot injection (pilot interval) and an interval between the main injection and the after injection (after interval) are calculated. In the present embodiment, the relationship between the engine operating state determined by the engine parameter and each control target value suitable for the same operating state, and the relationship between the engine operating state and the injection pattern suitable for the same operating state are determined through experiments and simulations. Based on the result, it is obtained in advance and stored in the main arithmetic processing unit 42 of the electronic control unit 40. Then, the main arithmetic processing unit 42 sets various control target values and injection patterns separately from the above relationships based on the engine parameters at that time.

  And the control target value (target injection period TAU) about the valve opening period of the fuel injection valve 20 is set from a model formula based on the said target injection amount and the fuel pressure PQ. In this embodiment, a physical model that models a fuel supply system including the common rail 34, each branch passage 31a, each fuel injection valve 20, and the like is constructed, and the target injection period TAU is calculated through the physical model. Specifically, a model formula having variables such as a target injection amount, fuel pressure PQ, and a learning correction term, which will be described later, is determined and stored in advance in the main arithmetic processing unit 42, and the target injection period TAU is calculated through the model formula. The

  Then, a drive signal is output from the electronic control unit 40 in a manner corresponding to the target injection timing and the target injection period TAU, and each fuel injection valve 20 is driven to open individually based on the input of this drive signal. As a result, an amount of fuel corresponding to the engine operating state is injected from each fuel injection valve 20 and supplied into each cylinder 11 of the internal combustion engine 10 with an injection pattern suitable for the engine operating state at that time. The rotational torque commensurate with the engine operating state is applied to the crankshaft 14.

  In the present embodiment, a learning process for learning the operating characteristics of the fuel injection valve 20 based on the fuel pressure PQ detected by the pressure sensor 51 is executed. In this learning process, first, a basic time waveform for a fuel injection rate is calculated based on various calculation parameters such as a target injection amount, a target injection timing, and a fuel pressure PQ. In the present embodiment, the relationship between the engine operation region determined by these calculation parameters and the basic time waveform suitable for the operation region is obtained in advance based on the results of various experiments and simulations, and the sub-processing unit 41 of the electronic control unit 40 is obtained. Is remembered. Then, the sub-processing unit 41 calculates a basic time waveform from the above relationship based on various calculation parameters.

  FIG. 3 shows an example of the basic time waveform. As shown by the solid line in FIG. 3, the basic time waveform includes the timing when the fuel injection valve 20 starts to open (valve opening operation timing To), and the rate of increase in the fuel injection rate after the start of valve opening ( Injection rate increase speed Vo), timing when valve closing operation is started (valve closing operation start timing Tc), fuel injection rate decrease rate Vc after valve closing starts, maximum value of fuel injection rate (maximum fuel injection rate Rm) A trapezoidal waveform defined by is set. In the present embodiment, the basic time waveform functions as a predetermined basic waveform.

On the other hand, based on the fuel pressure PQ detected by the pressure sensor 51, a time waveform (detection time waveform) of the actual fuel injection rate is formed. Specifically, first, based on the transition of the fuel pressure PQ, the valve opening operation start timing Tor, the injection rate increase speed Vor, the valve closing operation start timing Tcr, the injection rate decrease speed Vcr, and the maximum injection rate Rm of the fuel injection valve 20. Each r is specified. The fuel pressure inside the fuel injection valve 20 (specifically, the nozzle chamber 25) decreases as the lift amount increases when the fuel injection valve 20 is driven to open, and then lifts when the valve is driven to close. As the amount decreases, it increases. In the present embodiment, based on the transition of the fuel pressure inside the fuel injection valve 20 (specifically, the fuel pressure PQ), the valve opening operation start timing Tor, the injection rate increasing speed Vor, the valve closing operation start timing Tcr, The injection rate lowering speed Vcr and the maximum injection rate Rmr are specified with high accuracy. Then, as shown by a one-dot chain line in FIG. 3, a time waveform (detection time waveform) of the actual fuel injection rate is formed by the specified values. In the present embodiment, the detection time waveform functions as a fluctuation waveform when the fuel injection valve is driven to open with respect to the fuel pressure detected by the pressure sensor.

  In the learning process, the learning correction term is learned based on the relationship between the detection time waveform and the basic time waveform. That is, first, during the operation of the internal combustion engine 10, the detected time waveform and the basic time waveform are compared, and the difference between the parameters of these waveforms is sequentially calculated. Specifically, the difference between the parameters includes a difference ΔTog (= To−Tor) in the valve opening operation start timing, a difference ΔVog (= Vo−Vor) in the injection rate increasing speed, and a difference ΔTcg (= VcV) in the valve opening operation start timing. = Tc−Tcr), the difference ΔVcg (= Vc−Vcr) in the injection rate reduction rate, and the maximum injection rate ΔRmg (= Rm−Rmr). The differences ΔTog, ΔVog, ΔTcg, ΔVcg, and ΔRmg are stored in the sub-processing unit 41 as learning correction terms for compensating for variations in the operating characteristics of the fuel injection valve 20.

  In the present embodiment, these learning correction terms (ΔTog, ΔVog, ΔTcg, ΔVcg, ΔRmg) are used as calculation parameters for calculating the target injection period TAU based on the above-described model formula. By calculating the target injection period TAU in this way, the influence of the variation in the operating characteristics of the fuel injection valve 20 is compensated. In the present embodiment, the process of calculating the learning correction term based on the fuel pressure PQ is executed based on the output signal of the pressure sensor 51 corresponding to each cylinder 11 (# 1 to # 4) of the internal combustion engine 10. . In the apparatus according to the present embodiment, a plurality of learning regions defined by the fuel pressure PQ and the fuel injection amount (specifically, the target injection amount) are determined, and a learning correction term is learned and stored for each region. Is done.

  In the present embodiment, the injection pressure control is executed as follows. That is, first, a control target value (target fuel pressure) for the fuel pressure in the common rail 34 is calculated based on the passage air amount GA and the engine speed NE, and the fuel is set so that the actual fuel pressure becomes the target fuel pressure. The operation amount (fuel pressure feed amount or fuel return amount) of the pump 33 is adjusted. Through the adjustment of the operation amount of the fuel pump 33, the fuel pressure in the common rail 34, in other words, the fuel injection pressure of the fuel injection valve 20 is adjusted to a pressure corresponding to the engine operating state.

  As shown in FIG. 4, all of the pressure sensors 51 provided for each cylinder 11 (# 1 to # 4) of the internal combustion engine 10 are connected to the sub-processing unit 41. The sub operation processing device 41 executes the learning process.

  Two (# 1, # 4) of pressure sensors 51 provided for each cylinder 11 (# 1- # 4) of the internal combustion engine 10 are connected to the main arithmetic processing unit 42. In the apparatus according to the present embodiment, as indicated by a white arrow in FIG. 4, the sub arithmetic processing unit 41 and the main arithmetic processing unit 42 of the electronic control unit 40 are connected by a signal line. The data can be transferred between the device 41 and the main processing unit 42.

  The main arithmetic processing unit 42 executes arithmetic processing for reading the learning correction term from the sub arithmetic processing device 41 when calculating the target injection period TAU, and arithmetic processing for calculating the target injection period TAU from the model formula based on the learning correction term. .

  Further, the main arithmetic processing unit 42 performs arithmetic processing for calculating the target fuel pressure based on the engine parameter, and the target fuel pressure and the actual fuel pressure PQ (specifically, two pressure sensors 51 [# 1 connected to the same unit 42). , # 4], a process related to injection pressure control, such as a calculation process for adjusting the operation amount of the fuel pump 33 so as to coincide with the high pressure side value of the fuel pressure PQ).

  Here, the apparatus of the present embodiment executes a process for forming a detection time waveform based on the fuel pressure PQ detected by the pressure sensor 51. Therefore, compared with a device that learns the operating characteristics of the fuel injection valve 20 simply based on one of the detection values of the pressure sensor 51, the electronic control unit 40 (specifically, the sub-calculation processing device) 41 and the main arithmetic processing unit 42) tend to increase. Further, in the apparatus of the present embodiment, since the learning process is executed for each of the plurality of fuel injection valves 20, it can be said that the calculation load on the electronic control unit 40 is likely to increase from this point.

  In the apparatus of the present embodiment, when the learning process is simply executed based on the fuel pressure PQ detected by the pressure sensor 51, for example, when the fuel pressure PQ changes suddenly due to a change in the engine operating state, the internal combustion engine Depending on the operation state of 10, the learning accuracy of the operating characteristic of the fuel injection valve 20 in the learning process may be very low. In order to suppress such a decrease in learning accuracy, it is desirable to execute a determination process for determining whether or not the learning process can be executed based on the engine parameter. By executing such a determination process, a decrease in learning accuracy in the learning process can be suppressed, but the calculation load in the electronic control unit 40 is further concentrated. Such concentration of calculation load is not preferable because it causes a reduction in the degree of freedom in setting various calculation processes.

  In view of this point, in the apparatus according to the present embodiment, the main arithmetic processing unit 42 performs the above-described determination process, that is, engine parameters (specifically, engine speed NE, target injection amount, accelerator operation amount ACC, and fuel pressure PQ). An arithmetic process for determining whether or not to execute the learning process is executed based on the above. On the other hand, the sub arithmetic processing unit 41 receives and reads the determination result of the determination processing from the main arithmetic processing device 42 through data communication and executes the learning process according to the determination result.

  Thereby, when learning the operation characteristics of the fuel injection valve 20, the determination processing and the learning processing are executed by the different arithmetic processing devices 41 and 42, so that the arithmetic load is distributed to the arithmetic processing devices 41 and 42. Thus, the concentration of the computation load on one of the computation processing devices is suppressed. In addition, when the result of the determination process based on the engine parameter by the main arithmetic processing unit 42 is such that the learning process cannot be performed, the learning process by the sub-processing unit 41 is not executed, and the result of the determination process is the learning result. If the content indicates that the process can be executed, a learning process by the sub-processing unit 41 is executed. Therefore, when the engine is in an engine operating state in which the learning accuracy of the learning process may be lowered to a problem, the execution of the learning process can be prohibited, and the learning accuracy of the operating characteristics of the fuel injection valve 20 is reduced. Can be suppressed.

Hereinafter, the determination process and the learning process will be described in detail.
First, the determination process will be described.
FIG. 5 shows an execution procedure of the determination process. The series of processes shown in the flowchart of FIG. 11 is executed by the main arithmetic processing unit 42 as an interrupt process at predetermined intervals.

As shown in FIG. 5, in this process, it is first determined whether or not all of the following [Condition A] to [Condition D] are satisfied (Steps S10 to S13).
[Condition A] Parts constituting the fuel supply system are functioning normally (step S10). Specifically, in the process of step S10, there is no fuel leakage from the inside to the outside of the fuel supply system, and each fuel injection valve 20, each pressure sensor 51 (# 1, # 4), and the fuel pump 33 are When operating normally, it is determined that [Condition A] is satisfied.
[Condition B] The coolant temperature THW is within the predetermined temperature range AR1 (step S11). In the apparatus of the present embodiment, a temperature range (predetermined temperature range AR1) for the coolant temperature THW that allows the learning process to be accurately executed based on the results of various experiments and simulations is obtained in advance. It is stored in the arithmetic processing unit 42.
[Condition C] The fuel temperature THQ is within the predetermined temperature range AR2 (step S12). In the apparatus of the present embodiment, a temperature range (predetermined temperature range AR2) for the fuel temperature THQ that allows the learning process to be accurately executed based on the results of various experiments and simulations is obtained in advance, and the main calculation is performed. It is stored in the processing device 42.
[Condition D] The operating state of the internal combustion engine 10 determined by the engine parameters (engine rotational speed NE, target injection amount, accelerator operation amount ACC, fuel pressure PQ) is rapidly increased to the extent that a decrease in learning accuracy of the learning process becomes a problem. It is not in a changing state (transient operation state) (step S13). In the apparatus of the present embodiment, the relationship between the engine operation state determined by the engine parameters and the transient operation state based on the results of various experiments and simulations is obtained in advance and stored in the main arithmetic processing unit 42. Yes. In the process of step S13, it is determined from the above relationship based on the engine parameter whether or not it is in a transient operation state.

  When it is determined that all of [Condition A] to [Condition D] are satisfied (Steps S10 to S13 are “YES”), the learning execution flag is turned on (Step S14). . On the other hand, when it is determined that any one of [Condition A] to [Condition D] is not satisfied (any of Steps S10 to S13 is “NO”), the learning execution flag is turned off ( Step S15). After the learning execution flag is operated in this way, the present process is temporarily terminated.

Next, an execution procedure of a learning process, specifically, a process including the learning process and a process (characteristic learning control process) related to control for learning the operation characteristic of the fuel injection valve 20 will be described.
FIG. 6 shows an execution procedure of the characteristic learning control process. The series of processes shown in the flowchart of FIG. 11 is executed by the sub-processing unit 41 as an interrupt process at every predetermined cycle.

  As shown in FIG. 6, in this process, first, the determination result (specifically, the operation state of the learning execution flag) of the determination process (see FIG. 5) is read from the main arithmetic processing unit 42 through data communication. It is determined whether or not the execution flag is turned on (step S20).

  If the learning execution flag is turned on (step S20: YES), the learning process described above is executed (step S21). On the other hand, when the learning execution flag is turned off (step S20: NO), the learning process is not executed (the process of step S21 is jumped). After the learning process is executed according to the operation state of the learning execution flag as described above, this process is temporarily ended.

  In the apparatus according to the present embodiment, when the variation amount of the fuel pressure PQ due to a factor (disturbance) other than the opening / closing drive of the fuel injection valve 20 is large, the learning accuracy of the operating characteristics of the fuel injection valve 20 is reduced by the learning process. The possibility increases. In the determination process (FIG. 5), since [Condition D] (the process of step S13) is set, the determination process is executed based on the engine parameters including the fuel pressure PQ. Therefore, whether or not the learning process can be executed by the determination process can be appropriately executed in accordance with the magnitude of the fluctuation amount of the fuel pressure PQ due to the disturbance. Specifically, when the fluctuation amount of the fuel pressure PQ due to disturbance is large and the learning accuracy may become low enough to cause a problem, the learning execution flag is turned off and the learning process is prohibited. On the other hand, when the fluctuation amount of the fuel pressure PQ due to disturbance is small and the possibility of causing a decrease in learning accuracy is relatively low, the learning execution flag is turned on and execution of the learning process is permitted.

Hereinafter, the operation of the apparatus according to the present embodiment will be described.
In the example shown in FIG. 7, when the accelerator operation member ACC is operated at time T1 and the accelerator operation amount ACC (FIG. [A]) rapidly increases, the main arithmetic processing unit 42 performs a predetermined period ( From time T2 to T3), it is determined that the internal combustion engine 10 is in a transient operation state, and the learning execution flag ([c] in the figure) is turned off.

  When the accelerator operation member is operated at time T4 and the accelerator operation amount ACC decreases rapidly, the internal combustion engine 10 is in a transient operation state for a predetermined period (time T4 to T5) immediately after the determination processing by the main arithmetic processing unit 42. And the learning execution flag is turned off.

  In the apparatus of this embodiment, as is apparent from FIG. 7, the target fuel pressure (in the same manner as in the injection pressure control) in the period (the predetermined period T2 to T3, T4 to T5) determined as the transient operation state in the determination process. The one-dot chain line in FIG. [B] and the actual fuel pressure PQ (solid line in FIG. [B]) are greatly deviated. Therefore, if the learning process is executed during the same period, there is a high possibility that the learning accuracy will be reduced. In the apparatus of the present embodiment, the learning execution flag is turned off during the predetermined period, and the execution of the learning process by the sub-processing unit 41 is prohibited. As a result, a decrease in learning accuracy in the learning process can be suppressed.

As described above, according to the present embodiment, the following effects can be obtained.
(1) While the determination processing is executed by the main arithmetic processing device 42, the sub arithmetic processing device 41 receives and reads the determination result of the determination processing from the main arithmetic processing device 42 through data communication, and according to the determination result. The learning process was executed. Therefore, it is possible to suppress both the concentration of the calculation load on one of the calculation processing devices 41 and 42 and the decrease in the learning accuracy of the operating characteristics of the fuel injection valve 20.

  (2) The pressure sensor 51 for detecting the fuel pressure PQ inside the introduction passage 27 is integrally attached to the fuel injection valve 20. Therefore, a change in the fuel pressure inside the fuel injection valve 20 accompanying the opening of the fuel injection valve 20 can be detected with high accuracy, and learning of the operating characteristics of the fuel injection valve 20 based on the fuel pressure can be performed with high accuracy. Can be executed.

  (3) Since the determination process is executed based on the engine parameters including the fuel pressure PQ, whether or not the learning process can be executed by the determination process according to the magnitude of the fluctuation amount of the fuel pressure PQ due to the disturbance is appropriately determined. Can be executed.

The above embodiment may be modified as follows.
The execution procedure of the determination process (FIG. 5) is arbitrary as long as it can accurately determine that the learning accuracy in the learning process is likely to be a problem. Can be changed. Specifically, it is possible to omit [Condition A] (the process of Step S10), [Condition B] (the process of Step S11), and [Condition C] (the process of Step S12) in the determination process.

  As an engine parameter used for the determination process, not only the engine speed NE, the accelerator operation amount ACC, the target injection amount, and the fuel pressure PQ are adopted, but any engine parameter can be selected and adopted. Specifically, for example, only some of the engine speed NE, the accelerator operation amount ACC, the target injection amount, and the fuel pressure PQ are adopted, or other engine parameters (for example, the target injection timing and the target fuel pressure) are adopted. Etc.) may be adopted.

  The execution procedure of the learning process can be arbitrarily changed as long as it is an execution procedure that can learn the operating characteristics of the fuel injection valve 20 accurately based on the fuel pressure PQ detected by the pressure sensor 51. Examples of such execution procedures include [Specific Example 1] and [Specific Example 2]. [Specific Example 1] The actual fuel injection amount is calculated based on the variation mode of the fuel pressure PQ, and a learning correction term for correcting the target injection amount based on the difference between the fuel injection amount and the target injection amount is learned. . [Specific example 2] Based on the actual fuel pressure PQ at a specific timing when the fuel injection valve 20 is driven to open, a learning correction term for compensating for the influence due to the variation in the operating characteristics of the fuel injection valve 20 To learn.

  If the pressure that is an index of the fuel pressure inside the fuel injection valve 20 (specifically, in the nozzle chamber 25), in other words, the fuel pressure that changes with the change in the fuel pressure can be properly detected. The pressure sensor 51 is not limited to being directly attached to the fuel injection valve 20, and the manner of attaching the pressure sensor 51 can be arbitrarily changed. Specifically, the pressure sensor 51 may be attached to a portion (branch passage 31 a) between the common rail 34 and the fuel injection valve 20 in the fuel supply passage, or may be attached to the common rail 34.

  Instead of the type of fuel injection valve 20 driven by the piezoelectric actuator 29, a type of fuel injection valve driven by an electromagnetic actuator having a solenoid coil or the like may be employed.

The present invention can be applied not only to an internal combustion engine having four cylinders but also to an internal combustion engine having one to three cylinders, or an internal combustion engine having five or more cylinders.
The present invention can be applied not only to a diesel engine but also to a gasoline engine using gasoline fuel and a natural gas engine using natural gas fuel.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder, 12 ... Intake passage, 13 ... Piston, 14 ... Crankshaft, 15 ... Exhaust passage, 20 ... Fuel injection valve, 21 ... Housing, 22 ... Needle valve, 23 ... Injection hole, 24 ... Spring, 25 ... Nozzle chamber, 26 ... Pressure chamber, 27 ... Introduction passage, 28 ... Communication passage, 29 ... Piezoelectric actuator, 29a ... Valve element, 30 ... Discharge passage, 31a ... Branch passage, 31b ... Supply passage, 32 ... Fuel Tank, 33 ... fuel pump, 34 ... common rail, 35 ... return passage, 40 ... electronic control unit, 41 ... sub-processing unit ( second processing unit), 42 ... main processing unit ( first processing unit), DESCRIPTION OF SYMBOLS 51 ... Pressure sensor, 51A ... Sensor main body, 51B ... Memory, 52 ... Intake amount sensor, 53 ... Crank sensor, 54 ... Accelerator sensor, 55 ... Fuel temperature sensor, 56 Water temperature sensor.

Claims (5)

An internal combustion engine having a pressure sensor for detecting a fuel pressure inside a fuel supply system having a fuel injection valve, and performing a learning process for learning operating characteristics of the fuel injection valve based on the fuel pressure detected by the pressure sensor In the engine fuel injection characteristic learning device,
A first arithmetic processing unit that executes a determination process for determining whether or not to execute the learning process based on an engine parameter;
A second arithmetic processing unit that receives the determination result of the determination process from the first arithmetic processing unit and that executes the learning process according to the received determination result ;
The second arithmetic processing unit forms a fluctuation waveform of the fuel pressure detected by the pressure sensor when the fuel injection valve is driven to open, and based on a relationship between the fluctuation waveform and a predetermined basic waveform. A fuel injection characteristic learning device for an internal combustion engine, wherein a process for learning a learning correction term is executed as the learning process . The fuel injection characteristic learning device for an internal combustion engine according to claim 1,
  The determination process determines that the execution of the learning process is prohibited when the operation state of the internal combustion engine determined by the engine parameter is a transient operation state.
A fuel injection characteristic learning device for an internal combustion engine. The fuel injection characteristic learning device for an internal combustion engine according to claim 1 or 2,
The internal combustion engine has a plurality of cylinders;
The fuel injection valve is provided for each cylinder of the internal combustion engine,
The fuel injection characteristic learning device for an internal combustion engine, wherein the second arithmetic processing unit executes the learning process for each fuel injection valve provided for each cylinder of the internal combustion engine. The fuel injection characteristic learning device for an internal combustion engine according to claim 3,
The fuel injection characteristic learning device for an internal combustion engine, wherein the pressure sensor is integrally formed with each fuel injection valve provided for each cylinder. In the fuel injection characteristic learning device for an internal combustion engine according to any one of claims 1 to 4,
The fuel injection characteristic learning device for an internal combustion engine, wherein the engine parameter includes the fuel pressure.