JP2018100624A - Fuel injection controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection controller of an internal combustion engine capable of suppressing deterioration of followability of feedback control resulting from steady-state deviation.SOLUTION: A fuel injection controller of an internal combustion engine comprises a first map 41b configured to output a fixed feed-forward control value (fixation F/F control item), and a second map 41b configured to output a variable feed-forward control value (learning F/F control item) obtained by learning with a feedback value. The fuel injection controller is configured to perform feed-forward control so as to cancel steady-state deviation by the second map 41b, thereby suppress deterioration of followability of feedback control resulting from the steady-state deviation.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device that controls fuel injection using a control map.

  In fuel injection in an internal combustion engine such as a diesel engine, generally, an injection amount is calculated by adding a basic injection amount calculated by feedforward control and a correction amount calculated by feedback control (see, for example, Patent Document 1). ).

  By doing so, for example, even when an injector or the like deteriorates, fuel injection control that compensates for the deterioration by feedback control can be performed.

Japanese Patent Application Laid-Open No. 11-229942

  However, when all errors including steady deviations caused by injector deterioration or the like are compensated by feedback control, the follow-up performance of feedback control may be deteriorated. For example, when an error component due to temperature or the like is buried in a steady deviation component, the follow-up performance of feedback control with respect to a temperature change is deteriorated.

  The objective of this invention is providing the fuel-injection control apparatus of the internal combustion engine which can suppress the fall of the follow-up property of the feedback control resulting from a steady deviation.

One aspect of the fuel injection control device for an internal combustion engine of the present invention is:
A fuel injection control device for an internal combustion engine that controls fuel injection from an injector,
A feedforward control unit that feedforward-controls the fuel injection based on the engine speed and the accelerator opening;
A feedback control unit that feedback-controls the fuel injection based on the combustion state of the internal combustion engine;
Have
The feedforward control unit
A first map that outputs a fixed feedforward control value;
A second map for outputting a variable feedforward control value obtained by learning using a feedback value;
Have

  According to the present invention, a second map that outputs a variable feedforward control value obtained by learning using a feedback value is provided separately from the first map that outputs a fixed feedforward control value. The feedforward control that cancels out the steady deviation can be performed by the two maps, and the decrease in the follow-up performance of the feedback control due to the steady deviation can be suppressed.

1 is a schematic configuration diagram of an internal combustion engine according to an embodiment of the present invention. The figure which uses for description of the operation example of a combustion F / B control part The figure which uses for description of the structure of the combustion F / F control part by embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an internal combustion engine according to an embodiment of the present invention. As shown in FIG. 1, the internal combustion engine 1 includes an air cleaner 11, a turbocharger 12, an intercooler 13, a cylinder (combustion chamber) 14, a crank angle sensor 21, an in-cylinder pressure sensor 22, and an accelerator sensor 23. The intake passage 31, the exhaust passage 32, the injector 33, and an ECU (Engine Control Unit) 40 are provided. Although the internal combustion engine 1 has an intake throttle, EGR (Exhaust Gas Recirculation), etc., illustration is abbreviate | omitted in FIG.

  The turbocharger 12 includes a turbine 12a that rotates by the force of exhaust gas flowing in the exhaust passage 32, and a compressor 12b that rotates together with the turbine 12a and sends the air in the intake passage 31 to the cylinder 14. The air introduced from the air cleaner 11 into the intake passage 31 is pressurized by the compressor 12 b and sent into the cylinder 14 via the intercooler 13.

  The crank angle sensor 21 detects a crank angle θ of a crank provided in the cylinder 14. The crank angle sensor 21 outputs the detected crank angle θ to the ECU 40. The ECU 40 can calculate the rotational speed of the cylinder 14 using the crank angle θ.

  The in-cylinder pressure sensor 22 detects the in-cylinder pressure p of the cylinder 14. The in-cylinder pressure sensor 22 outputs the detected in-cylinder pressure p of the cylinder 14 to the ECU 40.

  The ECU 40 controls the entire internal combustion engine 1 and the operating state of the cylinder 14. As shown in FIG. 1, the ECU 40 includes a combustion F / F (F / B: feedforward) control unit 41 and a combustion F / B (F / B: feedback) control unit 42. The combustion F / F control unit 41 performs feedforward control of the fuel injection of the injector 33 based on the engine speed and the accelerator opening. The combustion F / B control unit 42 feedback-controls the fuel injection of the injector 33 based on the combustion state in the cylinder 14 (specifically, the in-cylinder pressure p and the crank angle θ). In practice, the ECU 40 also has a configuration for performing control other than feedforward and feedback control, but here, in order to simplify the description, the feedforward control and feedback control according to the present invention are performed. Only the configuration involved is described.

  The functions of the combustion F / F control unit 41 and the combustion F / B control unit 42 are realized by, for example, a CPU (Central Processing Unit).

  FIG. 2 is a diagram for explaining an operation example of the combustion F / B control unit 42. FIG. 2 shows the cylinder 14 and the combustion F / B control unit 42 shown in FIG. 1, and the others are omitted.

  As shown in FIG. 2, the combustion F / B control unit 42 includes a combustion gravity center calculation unit 42a, a torque calculation unit 42b, and an injection control unit 42c. The combustion gravity center calculation unit 42a calculates the fuel gravity center using, for example, the crank angle θ and the pressure increase rate dp / dθ. The torque calculator 42b calculates torque using, for example, the in-cylinder pressure p and the crank angle θ. In addition, about calculation of a fuel gravity center and a torque, not only this method but various known methods can be applied. The injection control unit 42c controls the injection timing and the injection amount of the injector 33 so that the combustion center of gravity and the torque approach the target.

  FIG. 3 is a diagram showing a configuration of the combustion F / F control unit 41 according to the present embodiment.

  The combustion F / F control unit 41 includes a first map 41a, a second map 41b, a learning correction term calculation unit 41c, and an addition unit 41d.

  A fixed feedforward control value (fixed F / F control term) is stored in advance in the first map 41a. The first map 41a inputs the engine speed obtained based on the crank angle θ detected by the crank angle sensor 21 and the accelerator opening detected by the accelerator sensor 23, and inputs the input engine speed and accelerator. By outputting a feedforward control value (fixed F / F control term) corresponding to the opening, feedforward control is performed so that the cylinder 14 is in a desired combustion state.

  The second map 41b outputs a variable feedforward control value (learning F / F control term) obtained by learning using a feedback value. Specifically, the second map 41b outputs a feedforward control value (learning F / F control term) that cancels out the steady deviation by multiplying the correction coefficient calculated by the learning correction term calculation unit 41c. Here, there are various methods for obtaining a control value that cancels out the steady deviation, and the present invention is not limited to this method, and thus will not be described in detail here. For example, the learning correction term calculation unit 41c is an engine. What is necessary is just to input a rotation speed, an accelerator opening degree, and a feedback value (cylinder pressure p, crank angle θ), and calculate a correction coefficient based on an I term in PID (Proportional-Integral-Differential) control.

  In the addition unit 41d, the fixed F / F control term output from the first map 41a and the learning F / F control term output from the second map 41b are added, and thereby the steady deviation from the addition unit 41d. The F / F control term is output so that can be removed.

  Actually, a learning F / F control term close to 0 is output from the second map 41b in an initial state where the injector or the like is not deteriorated. When the engine characteristics change due to deterioration of the injector or the like, a learning F / F control term is output from the second map 41b to remove the change (steady deviation) of the engine characteristics.

  In the adding unit 43, the F / F control term output from the adding unit 41d and the F / B control term output from the combustion F / B control unit 42 are added. A control value for controlling the fuel injection amount and injection timing of the injector 33 is output.

  In the present embodiment, a failure detection unit 44 that detects a failure based on the learning F / F control term output from the second map 41b is provided. The failure detection unit 44 can detect that a failure has occurred in the engine system when the value of the learning F / F control term is larger than a predetermined threshold value. That is, since the magnitude of the learning F / F control term output from the second map 41b corresponds to the magnitude of the steady deviation, in the present embodiment, the learning F / F control term is effectively used to correct the failure. It can also be detected.

  As described above, according to the present embodiment, the first map 41b that outputs a fixed feedforward control value (fixed F / F control term), and the variable feed obtained by learning using the feedback value. A second map 41b that outputs a forward control value (learning F / F control term), and feedforward control that cancels the steady deviation by the second map 41b is performed. It is possible to suppress a decrease in the follow-up performance of the resulting feedback control.

  In consideration of the feedforward control value (learning F / F control term) output from the second map 41b being a value corresponding to the steady-state deviation, this feedforward control value (learning F / F control term) Therefore, the failure can be detected with a simple configuration by effectively utilizing the learning F / F control term.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or main features thereof.

  The present invention is suitable for a fuel injection control device that performs feedforward control and feedback control.

1 Internal combustion engine 14 cylinders (combustion chamber)
21 Crank angle sensor 22 In-cylinder pressure sensor 23 Accelerator sensor 31 Intake passage 32 Exhaust passage 33 Injector 40 ECU
41 Combustion F / F control part 41a 1st map 41b 2nd map 41c Learning correction term calculation part 41d, 43 Addition part 42 Combustion F / B control part 44 Failure detection part

Claims (3)

A fuel injection control device for an internal combustion engine that controls fuel injection from an injector,
A feedforward control unit that feedforward-controls the fuel injection based on the engine speed and the accelerator opening;
A feedback control unit that feedback-controls the fuel injection based on the combustion state of the internal combustion engine;
Have
The feedforward control unit
A first map that outputs a fixed feedforward control value;
A second map for outputting a variable feedforward control value obtained by learning using a feedback value;
A fuel injection control device for an internal combustion engine. The feedforward control value output from the second map corresponds to a steady deviation from a target value when fuel injection is performed by the feedforward control value of the first map.
The fuel injection control device for an internal combustion engine according to claim 1. A failure detection unit that detects a failure based on a feedforward control value output from the second map;
The fuel injection control device for an internal combustion engine according to claim 1 or 2.

Images