JP2005171893A - Supercharging pressure control device - Google Patents

Abstract

An object of the present invention is to reliably suppress occurrence of overshoot by feedback control when an actual supercharging pressure falls below a target supercharging pressure due to a supercharging delay in a transient state.
An engine ECU 41 feedback-controls the nozzle opening of a nozzle vane 23 through a variable nozzle mechanism 19 so that an actual supercharging pressure by a variable nozzle turbocharger 15 approaches a target supercharging pressure corresponding to an operating state of the engine 11. . Further, the engine ECU 41 determines a transient state for the supercharging pressure based on at least a change mode of the deviation between the target supercharging pressure and the actual supercharging pressure. Specifically, it is determined whether or not the rate of change, which is the amount of change per unit time of deviation, is out of a predetermined range. When it is determined that the rate of change is out of the range and the boost pressure is in a transient state, the engine ECU 41 inhibits the update of the integral term in the feedback control and suppresses the increase of the feedback term, thereby feedback. Suppress control.
[Selection] Figure 1

Description

  The present invention provides a supercharger (turbocharger) having a supercharging pressure varying means such as a variable nozzle mechanism so that an actual supercharging pressure approaches a target supercharging pressure corresponding to an engine operating state. The present invention relates to a supercharging pressure control device that performs feedback control of an operation amount of a pressure varying means.

  As a means for improving engine output, a variable nozzle turbocharger is provided with a variable vane (nozzle vane) on the outer periphery of the turbine, and the supercharging pressure can be adjusted by changing the inclination (opening) with a variable nozzle mechanism. It has been known. In this type of turbocharger, a target supercharging pressure is set according to the operating state of the engine, and a variable nozzle mechanism is used so that the actual supercharging pressure (actual supercharging pressure) in the intake passage approaches the target supercharging pressure. The nozzle opening (operation amount) of the nozzle vane is feedback controlled.

  In this feedback control, the integral term in the feedback term is set according to the deviation between the target boost pressure and the actual boost pressure in order to absorb variations in the turbocharging pressure due to machine differences in the variable nozzle turbocharger and changes over time. Storage and updating (learning) are performed. However, in any turbocharger in a transient state such as during acceleration, a state in which the actual supercharging pressure is lower than the target supercharging pressure always occurs due to a supercharging delay. If the integral term is erroneously updated in this transient state, the integral term is updated to a large value in order to bring the actual boost pressure closer to the target boost pressure. If a feedback term including this integral term is used to feedback control the nozzle opening of the nozzle vane, a phenomenon (overshoot) that further increases after the actual boost pressure reaches the target boost pressure may occur. There is.

  The overshoot of the supercharging pressure can cause a decrease in the reliability of each part of the engine including the turbocharger. For example, the intake system hose may come off, the intercooler may be damaged, the impeller may be damaged due to excessive turbine rotation, or the in-cylinder pressure may be increased to damage the engine body.

  In order to suppress such a decrease in reliability, when there is a possibility of overshooting, for example, it is conceivable to increase the nozzle opening by operating the nozzle vane to the open side. A new problem occurs that causes a decrease in feed responsiveness.

  Therefore, in order to solve the above problem, the prohibition condition is “the deviation between the target boost pressure and the actual boost pressure is greater than a predetermined determination value”, and when this prohibition condition is satisfied, the integral term It is conceivable to inhibit the overshoot by preventing the integral term from being updated erroneously and causing the feedback term to become excessive by prohibiting the update of (see, for example, Patent Document 1).

In addition to Patent Document 1, Patent Document 2 is given as a prior art document according to the present invention.
JP 2001-65358 A JP 2001-214749 A

  However, if the prohibition condition is that “the deviation between the target boost pressure and the actual boost pressure is greater than a predetermined determination value” as described above, erroneous update (mislearning) in a transient state is prevented to some extent. Is still inadequate. For example, the state immediately before the actual boost pressure follows the target boost pressure is also a transient state. However, at this time, since the deviation between the two supercharging pressures becomes small and the prohibition condition is not satisfied, the integral term and thus the feedback term are erroneously updated.

  Further, if the determination value is set to a small value in order to prevent the erroneous update as described above, the integral term under the condition that should be updated, that is, under the condition where both supercharging pressures are stable. Is not updated, and it becomes difficult to absorb variations in supercharging pressure due to machine differences and changes with time.

  The present invention has been made in view of such circumstances, and its purpose is to cause overshoot by feedback control when the actual supercharging pressure falls below the target supercharging pressure due to a supercharging delay in a transient state. An object of the present invention is to provide a supercharging pressure control device capable of reliably suppressing the above. Further, another object of the present invention is to ensure that even if the actual supercharging pressure falls below the target supercharging pressure due to the supercharging delay in the transient state described above, the variation of the supercharging pressure due to machine difference or the like is ensured. An object of the present invention is to provide a supercharging pressure control device capable of absorbing.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, the turbocharger is used in an exhaust drive supercharger having a supercharging pressure varying means, and the actual supercharging pressure by the exhaust drive supercharger is a target supercharging pressure corresponding to the engine operating state. In a supercharging pressure control device comprising supercharging pressure control means for feedback-controlling the operation amount of the supercharging pressure varying means so as to approach It is assumed that the apparatus includes a transient state determination unit that determines a transient state with respect to the supply pressure, and a feedback control suppression unit that suppresses feedback control by the boost pressure control unit according to the transient determination by the transient state determination unit.

  According to the above configuration, in the supercharging pressure control means, basically, the supercharging pressure can be varied so that the actual supercharging pressure by the exhaust driving supercharger approaches the target supercharging pressure corresponding to the engine operating state. The operation amount of the means is feedback controlled. In this exhaust-driven supercharger, in a transient state such as during acceleration, a state where the actual supercharging pressure is lower than the target supercharging pressure occurs due to a supercharging delay. At this time, if the operation amount of the supercharging pressure varying means is changed to a large value by feedback control in order to bring the actual supercharging pressure closer to the target supercharging pressure, it will become excessive after the actual supercharging pressure matches the target supercharging pressure. (Overshoot) may occur.

  In this regard, in the invention described in claim 1, in such feedback control, the transient state determination means performs the transient state with respect to the supercharging pressure based on at least a change mode of the deviation between the target supercharging pressure and the actual supercharging pressure. It is determined whether it exists. If this deviation does not change much (the deviation is maintained), the supercharging pressure is stable, that is, it is not a transient state. This is true even if there is a variation in supercharging pressure due to machine differences or changes over time. When the transient state determination unit determines that the state is a transient state, the feedback control suppression unit suppresses feedback control. Therefore, even if a supercharging delay occurs in a transient state such as during acceleration and the actual supercharging pressure is significantly lower than the target supercharging pressure, the overshoot of the supercharging pressure is suppressed by suppressing the feedback control. . Thereafter, when it is determined that the state is not a transient state based on the variation mode of the deviation, the above suppression is released and normal feedback control is performed.

  The exhaust-drive supercharger having the above-described supercharging pressure varying means is a turbine wheel that rotates when engine exhaust is blown, and is opened and closed to make the flow rate of the exhaust blown to the turbine wheel variable. A so-called variable nozzle turbocharger with an operating nozzle vane can be used. In this exhaust driving supercharger, the nozzle vane and a mechanism for opening and closing the nozzle vane (for example, a variable nozzle mechanism) correspond to the supercharging pressure varying means. Further, the nozzle opening degree of the nozzle vane corresponds to the operation amount of the supercharging pressure varying means that is the object of feedback control by the supercharging pressure control means.

  According to a second aspect of the present invention, in the first aspect of the invention, the transient state determining means uses a change rate, which is a change amount of the deviation per time, as a change mode of the deviation, with respect to a boost pressure. It is assumed that a transient state is determined.

  According to the above configuration, when the transient state determination unit determines the transient state with respect to the supercharging pressure, the change rate of the deviation is used as a change mode of the deviation. This rate of change is the amount of change per time for the deviation between the target boost pressure and the actual boost pressure. If the deviation does not change much, the rate of change should vary around “0”. Therefore, by using this rate of change, it is possible to accurately determine whether the supercharging pressure is stable or changing (in a transient state).

  According to a third aspect of the present invention, in the second aspect of the present invention, the transient state determining means determines that the transition state is in a transient state when the rate of change of the deviation is out of a predetermined range. .

  Here, when the rate of change of the deviation for the supercharging pressure is within the predetermined range, the deviation between the target supercharging pressure and the actual supercharging pressure has not changed much, and the supercharging pressure has stabilized. It can be said that. On the other hand, when the rate of change is out of the predetermined range, it can be said that the deviation fluctuates relatively greatly and the supercharging pressure is in a transient state.

  In this regard, according to the third aspect of the present invention, in the determination by the transient state determination means, if the change rate of the deviation is out of the predetermined range, it is determined that the state is in the transient state. Therefore, by appropriately setting the predetermined range, it is possible to reliably determine whether or not the state is a transient state by comparing the rate of change with the predetermined range.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the feedback control suppressing means increases the feedback term in the feedback control according to the transient determination by the transient state determining means. It is assumed that the feedback control is suppressed by suppressing.

  Here, when a state where the actual boost pressure falls below the target boost pressure occurs due to a delay in boost in a transient state such as during acceleration, the boost pressure control means should bring the actual boost pressure closer to the target boost pressure. If the feedback term is changed to a large value, overshoot may occur after the actual supercharging pressure matches the target supercharging pressure.

  In this regard, in the invention according to the fourth aspect, when the transient state determination unit determines that the state is the transient state, the feedback control suppression unit suppresses the increase of the feedback term in the feedback control. Therefore, even if a supercharging delay occurs in a transient state such as during acceleration and the actual supercharging pressure is significantly lower than the target supercharging pressure, the increase in the feedback term is suppressed, thereby suppressing supercharging pressure overshoot. Is possible.

  In the invention according to claim 5, in the invention according to any one of claims 1 to 4, the feedback item is stored and updated in accordance with a deviation between the target boost pressure and the actual boost pressure. It is assumed that the feedback control suppression unit suppresses an increase in the feedback term by prohibiting the update of the integral term in response to the transient determination by the transient state determination unit.

  In feedback control, the integral term in the feedback term depends on the deviation between the target boost pressure and the actual boost pressure in order to absorb variations in the boost pressure due to machine differences in exhaust-driven turbochargers and changes over time. Stored and updated. If the update of this integral term is mistakenly performed when the actual boost pressure is lower than the target boost pressure due to a turbocharge delay in a transient state such as during acceleration, the actual boost pressure will be The integral term is updated to an excessively large value to approach the pressure. If a feedback term including this integral term is used to feedback-control the operation amount of the supercharging pressure varying means, there is a risk of overshooting after the actual supercharging pressure reaches the target supercharging pressure.

  In this regard, in the invention described in claim 5, when the transient state determination means determines that the state is in the transient state, the update of the integral term is prohibited. Along with this, an increase in the feedback term and, consequently, feedback control is suppressed. Therefore, even if a supercharging delay occurs in a transient state such as during acceleration and the actual supercharging pressure is significantly lower than the target supercharging pressure, the supercharging is performed while absorbing the variation in supercharging pressure due to machine differences. It is possible to reliably suppress pressure overshoot.

Hereinafter, an embodiment embodying a supercharging pressure control device of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an engine 11 is mounted on the vehicle. In the engine 11, air outside the engine 11 passes through the intake passage 12 as intake air and is taken into the combustion chamber 11a. Further, the fuel supplied from the fuel injection valve is burned in the combustion chamber 11a. And the crankshaft 13 which is an output shaft is rotationally driven by the energy generated by combustion. Gas (exhaust gas) generated by the combustion passes through the exhaust passage 14 and is discharged to the outside of the engine 11.

  The engine 11 is provided with a variable nozzle turbocharger 15 which is a form of an exhaust drive supercharger (turbocharger). The variable nozzle turbocharger 15 is a turbine wheel 16 that is rotated by exhaust flowing in the exhaust passage 14, and a compressor wheel 17 that is disposed in the intake passage 12 and is connected to the turbine wheel 16 via a rotor shaft 18 so as to be integrally rotatable. It has. In the variable nozzle turbocharger 15, exhaust is blown to the turbine wheel 16 and the turbine wheel 16 rotates. This rotation is transmitted to the compressor wheel 17 via the rotor shaft 18. As a result, in the engine 11, not only is air taken into the combustion chamber 11 a due to the negative pressure generated in the combustion chamber 11 a as the piston moves, but the air is forcibly forced by the rotation of the compressor wheel 17. Is sent (supercharged). In this way, the efficiency of filling the combustion chamber 11a with air is increased.

  In the variable nozzle turbocharger 15, an exhaust path is formed along the rotation direction of the turbine wheel 16 so as to surround the outer periphery of the turbine wheel 16. For this reason, the exhaust passes through the exhaust path and is blown toward the axis of the turbine wheel 16. A variable nozzle mechanism 19 formed of a valve mechanism is provided in the exhaust path as a supercharging pressure variable means. Then, the variable nozzle mechanism 19 opens and closes to change the exhaust flow area of the exhaust path so that the flow velocity of the exhaust blown to the turbine wheel 16 is variable. By making it variable in this way, the rotational speed of the turbine wheel 16 is adjusted, and the amount and pressure (supercharging pressure) of air forcedly fed into the combustion chamber 11a are adjusted.

  Next, the structure of the variable nozzle mechanism 19 will be described with reference to FIGS. 2 is a front view of the variable nozzle mechanism 19 as seen from the compressor wheel 17 side (upper side in FIG. 1), and FIG. 3 is a sectional view taken along line XX in FIG. In FIG. 3, the illustration of the vicinity of the center of the variable nozzle mechanism 19 is omitted.

  As shown in FIGS. 2 and 3, the variable nozzle mechanism 19 includes a ring-shaped nozzle back plate 21. The nozzle back plate 21 is provided with a plurality of shafts 22 at substantially equal angles around the center O of the plate 21. Each shaft 22 is rotatably inserted into the nozzle back plate 21. For each shaft 22, a nozzle vane (variable nozzle) 23 is fixed to one end portion (lower end portion in FIG. 3) exposed from the nozzle back plate 21. Further, for each shaft 22, an opening / closing lever 24 is fixed as a driven body to the other end portion (upper end portion in FIG. 3) exposed from the nozzle back plate 21. Each open / close lever 24 extends toward the outer edge of the nozzle back plate 21 perpendicular to the shaft 22. A pair of sandwiching portions 24 a that are bifurcated are formed at the tip of each open / close lever 24.

  A ring plate 25 is disposed between each open / close lever 24 and the nozzle back plate 21 so as to overlap the nozzle back plate 21. A direct current (DC) motor 27 is drivingly connected to the ring plate 25 via transmission means such as a link mechanism 26 (see FIG. 1). The DC motor 27 is used as an actuator for rotating the ring plate 25 in the circumferential direction. A plurality of pins 28 are fixed to the ring plate 25 at substantially equal angles with the circle center O as the center. Each pin 28 is rotatably held by the holding portion 24a of the opening / closing lever 24 described above. In this way, all the nozzle vanes 23 are connected to the common ring plate 25 via the shaft 22, the opening / closing lever 24 and the pin 28.

  Therefore, when the ring plate 25 is rotated around the circle center O by the DC motor 27, each pin 28 is also displaced in the same direction. Due to this displacement, each pin 28 pushes the clamping portion 24 a of each opening / closing lever 24 in the rotation direction of the ring plate 25. In response to this pressing, each open / close lever 24 rotates around the shaft 22 as a unit. Along with this rotation, each nozzle vane 23 opens and closes in a synchronized state around the shaft 22. Accordingly, the gap between the adjacent nozzle vanes 23 becomes a size corresponding to the rotation angle (nozzle opening degree) of each nozzle vane 23, and the flow rate of the exhaust blown to the turbine wheel 16 through the exhaust path is adjusted. The For example, when the nozzle vane 23 rotates to the closed side, the flow velocity of the exhaust gas sprayed to the turbine wheel 16 increases. On the contrary, when the nozzle vane 23 rotates to the opening side, the flow velocity of the exhaust gas sprayed to the turbine wheel 16 becomes small.

  The movable range (opening / closing range) of each nozzle vane 23 is regulated by a stopper 29 provided on the nozzle back plate 21. Although three stoppers 29 are provided in FIG. 2, this number can be changed as appropriate. As shown in FIG. 4, the stopper 29 is positioned between the adjacent opening / closing levers 24. When the nozzle vane 23 is rotated to the maximum open side, one of the adjacent opening / closing levers 24 (downward in FIG. 4) is abutted against the stopper 29 as shown by the solid line. Further, when the nozzle vane 23 is rotated to the maximum closed side, the other of the adjacent opening / closing levers 24 (upward in FIG. 4) is abutted against the stopper 29 as indicated by a two-dot chain line. Thus, the nozzle opening degree of the nozzle vane 23 is variable within the opening / closing range restricted by the stopper 29.

  As shown in FIG. 1, the vehicle is provided with various sensors 31 to 34 for detecting the operating state of the engine 11. For example, a crank angle sensor 31 that outputs a pulse signal every time the crankshaft 13 rotates by a predetermined angle is disposed in the vicinity of the crankshaft 13. This pulse signal is used to calculate the engine speed ene, which is the number of revolutions of the crankshaft 13 per time. A water temperature sensor 32 that detects the temperature of the cooling water flowing through the engine 11 (cooling water temperature) is attached to the cylinder block of the engine 11. In the vicinity of the accelerator pedal, an accelerator sensor 33 for detecting the amount of depression of the pedal by the driver is disposed. The intake passage 12 is provided with an intake pressure sensor 34 that detects intake pressure, which is the pressure of intake air.

  The vehicle is provided with an engine electronic control unit (hereinafter referred to as “engine ECU”) 41 as means for controlling the operation of each part of the engine 11 based on the detection values of these sensors 31 to 34. The engine ECU 41 is configured around a microcomputer. In the engine ECU 41, a central processing unit (CPU) performs arithmetic processing according to control programs and initial data stored in a read-only memory (ROM) based on detection values of various sensors 31 to 34, and based on the calculation results. Various controls. The calculation result by the CPU is temporarily stored in a random access memory (RAM). Further, the engine ECU 41 is provided with a backup RAM for storing and holding various data even after power supply is stopped. One of the stored data is an integral term epvnpmi (i) in feedback control described later.

  The engine ECU 41 executes, for example, fuel injection control as the various controls. In this fuel injection control, the amount of fuel injected from the fuel injection valve and the injection timing (both are target values) are determined based on the engine rotational speed ene by the crank angle sensor 31, the accelerator depression amount by the accelerator sensor 33, and the cooling by the water temperature sensor 32. Determine based on water temperature. When the output signal of the crank angle sensor 31 coincides with the fuel injection start timing, energization of the fuel injection valve is started. The energization is stopped when the injection time corresponding to the injected fuel amount has elapsed from this start time.

  The engine ECU 41 controls the supercharging pressure by opening and closing the nozzle vane 23. In this control, the target supercharging pressure epimtrg corresponding to the operating state of the engine 11 is calculated, and the opening degree of the nozzle vane 23 is adjusted so that the actual supercharging pressure epim detected by the intake pressure sensor 34 approaches the target supercharging pressure epimtrg. (Nozzle opening) is feedback controlled.

  In this feedback control, the final command value of the nozzle opening (final opening epvnfin) is calculated according to the following equation (1). This final opening degree epvnfin corresponds to a control command value used for driving control of the DC motor 27.

epvnfin = min (max (epbnbse + epvnpmfb, epvnmin), epvnmax) (1)
epbnbse: Base term
epvnpmfb: Feedback term
epvnmin: Minimum guard value
epvnmax: Maximum guard value According to the above equation (1), the value obtained by adding the feedback term epvnpmfb to the base term epbnbse is compared with the minimum guard value epvnmin, and the larger value is selected. Further, the selected value is compared with the maximum guard value epvnmax, and the smaller value is selected as the final opening epvnfin.

The feedback term epvnpmfb in the above equation (1) is calculated according to the following equation (2).
epvnpmfb = epvnpmp + epvnpmi + epvnpmd (2)
(However, EPVNFBMN ≤ epvnpmi ≤ EPVNFBMX)
epvnpmp: proportional term
epvnpmi: integral term
epvnpmd: differential term
EPVNFBMN: Lower limit guard value
EPVNFBMX: Upper limit guard value Proportional term epvnpmp is a control amount for outputting an operation amount (nozzle opening) proportional to the deviation (supercharging pressure deviation epimdlt) between the target supercharging pressure epimtrg and the actual supercharging pressure epim . The integral term epvnpmi is a control amount for outputting an operation amount proportional to the integral value of the supercharging pressure deviation epimdlt. The differential term epvnpmd is a control amount for outputting an operation amount proportional to a change in the supercharging pressure deviation epimdlt.

  The final opening degree epvnfin calculated as described above is set to a value closer to 0% as the nozzle vane 23 is controlled to the open side, and to a value closer to 100% as the nozzle vane 23 is controlled to the closed side. Is done.

  The series of processes by the engine ECU 41 corresponds to a supercharging pressure control unit that feedback-controls the nozzle opening degree of the nozzle vane 23 so that the actual supercharging pressure epim approaches the target supercharging pressure epimtrg.

  In addition to the engine ECU 41, a turbo controller 43 is provided as means for directly controlling the nozzle opening of the nozzle vane 23. The turbo controller 43 is connected to the engine ECU 41, and receives the final opening epvnfin from the engine ECU 41 by communication. Furthermore, a nozzle opening sensor 44 is connected to the turbo controller 43 as means for detecting the nozzle opening of the variable nozzle (nozzle vane 23). The turbo controller 43 is common to the engine ECU 41 in that it includes a CPU, a ROM, and a RAM. However, it differs from the engine ECU 41 in that it includes a current detection circuit 42 that detects the value of the current flowing through the DC motor 27. The detection value of the current detection circuit 42 is transmitted to the engine ECU 41. The turbo controller 43 controls the current passed through the DC motor 27 so that the actual nozzle opening detected by the nozzle opening sensor 44 approaches the final opening epvnfin received from the engine ECU 41. In this way, the actual supercharging pressure epim is brought close to the target supercharging pressure epimtrg by bringing the nozzle opening of the nozzle vane 23 close to the final opening epvnfin.

  By the way, in the above feedback control, the integral term epvnpmi (i) is stored and updated according to the supercharging pressure deviation epimdlt in order to absorb the variation of the actual supercharging pressure epim due to the machine difference of the variable nozzle turbocharger 15 and the change with time. (Learning) is done. However, in any turbocharger in a transient state such as at the time of acceleration, a state where the actual supercharging pressure epim falls below the target supercharging pressure epimtrg always occurs due to a supercharging delay. If the integral term epvnpmi (i) is mistakenly updated (mis-learned) in this transient state, the actual boost pressure after the increased integral term epvnpmi (i) matches the target boost pressure epimtrg May cause epim overshoot.

  Therefore, in the present embodiment, in order to suppress such overshoot, it is determined whether or not it is a transient state with respect to the supercharging pressure, based on a variation aspect of the deviation between the target supercharging pressure epimtrg and the actual supercharging pressure epim, The feedback control is suppressed when it is determined that the state is a transient state. Next, the calculation process of the integral term epvnpmi (i) reflecting this suppression will be described. The flowchart of FIG. 5 shows a routine (integral term calculation routine) for calculating the integral term epvnpmi (i) among the processes performed by the engine ECU 41, and is executed at regular intervals.

In this routine, first, in step 100, the engine ECU 41 calculates the supercharging pressure deviation epimdlt by subtracting the actual supercharging pressure epim from the target supercharging pressure epimtrg.
Next, in step 105, it is determined whether any of the following integral term update prohibition conditions shown in (i) to (vii) is satisfied.

(i) It must be during deceleration.
(ii) At the start of acceleration.
(iii) At low supercharging pressure.

(iv) The supercharging pressure deviation epimdlt is smaller than a certain value.
(v) The supercharging pressure deviation epimdlt is larger than a certain value.
(vi) The feedback limit has already been reached in a controllable manner.

  For example, the actual boost pressure epim has not yet matched the target boost pressure epimtrg, but the feedback term epvnpmfb (i-1) immediately before the integral term epvnpmi (i) is updated is already guarded by the maximum guard value. about.

  In addition, the actual supercharging pressure epim increases (overshoots) after it matches the target supercharging pressure epimtrg, and the feedback term epvnpmfb (i-1) immediately before the integral term epvnpmi (i) is updated is already the minimum guard. Guarded by value.

(vii) The rate of change epimddlt, which is the amount of change in supercharging pressure deviation epimdlt per time, is out of the predetermined range R1. That is, if the lower limit of range R1 is EPIMDDIDW and the upper limit is EPIMDDIUP,
epimddlt <EPIMDDIDW or epimddlt> EPIMDDIUP
Be. Here, the lower limit value EPIMDDIDW is set to “−0.5”, and the upper limit value EPIMDDIUP is set to “+0.5”.

  If the supercharging pressure deviation obtained in the previous control cycle is assumed to be epimdlto, the integral term calculation routine is executed at regular intervals, so the change rate epimddlt is calculated according to the following equation (3).

epimddlt = epimdlt−epimdlto (3)
The process of step 105 by the engine ECU 41 is a transient that determines whether or not the actual supercharging pressure epim is in a transient state based on at least the change of the target supercharging pressure epimtrg and the supercharging pressure deviation epimdlt of the actual supercharging pressure epim. It corresponds to a state determination means.

  If all of the integral term update prohibiting conditions (i) to (vii) are not satisfied and the determination condition of step 105 is not satisfied, the process proceeds to the next steps 110 to 125. In these steps 110 to 125, the integral term epvnpmi (i) stored in the backup RAM is updated a predetermined amount on condition that the supercharging pressure deviation epimdlt is out of the predetermined range R2 (= EPIMDW to EPIMUP). Updates with the quantity epvnpmid.

  In step 110, it is determined whether the supercharging pressure deviation epimdlt is larger than the upper limit value EPIMUP of the range R2. If this determination condition is satisfied (epimdlt> EPIMUP), in step 115, the update amount epvnpmid is added to the integral term epvnpmi (i-1) obtained in the previous control cycle, and the addition result is a new integral term. Set as epvnpmi (i).

  On the other hand, if the determination condition in step 110 is not satisfied (epimdlt ≦ EPIMUP), it is determined in step 120 whether the supercharging pressure deviation epimdlt is smaller than the lower limit value EPIMDW of the range R2. If this determination condition is satisfied (epimdlt <EPIMDW), in step 125, the update amount epvnpmid is subtracted from the integral term epvnpmi (i-1) obtained in the previous control cycle, and the subtraction result is replaced with a new integral term. Set as epvnpmi (i).

  On the other hand, when at least one of the integral term update prohibition conditions (i) to (vii) is satisfied and the determination condition of step 105 described above is satisfied, and the supercharging pressure deviation epimdlt is within the range R2. If the determination condition of step 120 is not satisfied, the routine proceeds to step 130. In step 130, without performing the updating process in steps 115 and 125 described above (inhibiting the update), the integral term epvnpmi (i-1) obtained in the previous control cycle is directly used as a new integral term epvnpmi (i). Set as.

  After the processing in steps 115, 125, and 130, guard processing is performed in steps 135 to 150. In step 135, it is determined whether the integral term epvnpmi (i) is larger than a predetermined upper guard value EPVNIMX. If this determination condition is satisfied (epvnpmi (i)> EPVNIMX), in step 140, the upper limit guard value EPVNIMX is set as the integral term epvnpmi (i), and this integral term calculation routine is terminated.

  On the other hand, if the determination condition of step 135 is not satisfied (epvnpmi (i) ≦ EPVNIMX), in step 145, the integral term epvnpmi (i) is smaller than the predetermined lower guard value EPVNIMN (<EPVNIMX). Determine whether or not. If this determination condition is satisfied (epvnpmi (i) <EPVNIMN), in step 150, the lower limit guard value EPVNIMN is set as the integral term epvnpmi (i), and this integral term calculation routine is terminated. If the determination condition in step 145 is not satisfied, that is, if the integral term epvnpmi (i) is within the range of EPVNIMN to EPVNIMX, the process in steps 140 and 150 described above is not performed. This integral term calculation routine is terminated.

  The processing of steps 105 and 130 by the engine ECU 41 in the integral term calculation routine is a feedback that suppresses feedback control when it is determined that the actual boost pressure epim is in a transient state as a result of comparison between the change rate epimddlt and the range R1. This corresponds to control suppression means.

  When the nozzle opening is feedback controlled based on the final opening epvnfin calculated using the integral term epvnpmi (i) by the integral term calculation routine, the target boost pressure epimtrg, the actual boost pressure epim, the change rate epidimdlt and The integral term epvnpmi (i) changes as shown in FIG. 6, for example.

  When acceleration of the vehicle is started at timing t1, the actual supercharging pressure epim falls below the target supercharging pressure epimtrg due to the supercharging delay, but the actual supercharging pressure epim is set to the target by feedback control of the nozzle opening of the nozzle vane 23. Gradually approaches the supercharging pressure epimtrg. Along with this, the supercharging pressure deviation epimdlt becomes smaller. Immediately before the timing t2 when the actual supercharging pressure epim matches the target supercharging pressure epimtrg, the supercharging pressure deviation epimdlt is small and the change rate epimddlt is out of the range R1. Since the integral term update prohibition condition (vii) is satisfied, the integral term calculation routine performs processing in the order of steps 105 → 130, and the integral term epvnpmi (i) is not updated.

  Then, the actual supercharging pressure epim stabilizes after it coincides with the target supercharging pressure epimtrg, the rate of change epidimdlt falls within the range R1 (= ± 0.5), and other integral term update prohibition conditions (i) to ( If neither of vi) is satisfied, the integral term epvnpmi (i) is updated in the period from timing t3 to t4 and in the period from timing t5 to t6. In this way, the integral term epvnpmi (i) is not updated in the transient state immediately before the actual supercharging pressure epim matches the target supercharging pressure epimtrg, and both supercharging pressures epim and epimtrg are stable (non-transient state). Only the integral term epvnpmi (i) is updated. As a result, even after the actual supercharging pressure epim coincides with the target supercharging pressure epimtrg, it follows the target supercharging pressure epimtrg without greatly overshooting.

  FIG. 7 shows the target supercharging pressure epimtrg, actual supercharging pressure epim, change rate when the integral term update prohibiting condition (vii) is omitted (corresponding to Patent Document 1) for comparison with the present embodiment. Fig. 3 shows one embodiment of changes in epimddlt and integral term epvnpmi (i).

  In the period from timing t11 to t12 immediately before the actual boost pressure epim matches the target boost pressure epimtrg, the boost pressure deviation epimdlt is small and the integral term update prohibition condition (v) is not satisfied. Therefore, if the other integral term update prohibition conditions (i) to (iv) and (vi) are not satisfied, the actual boost pressure epim is approaching the target boost pressure epimtrg, that is, in a transient state. Nevertheless, the integral term epvnpmi (i) is erroneously updated to the plus side. Therefore, the actual supercharging pressure epim matches the target supercharging pressure epimtrg because the nozzle opening of the nozzle vane 23 is feedback controlled based on the final opening epvnfin calculated using the increased integral term epvnpmi (i). After the timing t13, it continues to increase for a while, so-called overshoot occurs.

According to the embodiment described in detail above, the following effects can be obtained.
(1) If the deviation (supercharging pressure deviation epimdlt) between the target supercharging pressure epimtrg and the actual supercharging pressure epim does not change much (the supercharging pressure deviation epimdlt is maintained), the target supercharging pressure epimtrg and actual The supercharging pressure epim is stable, that is, not in a transient state. This can be said even if there is a variation in supercharging pressure due to machine differences or changes over time.

  In this respect, it is determined whether or not it is in a transient state with respect to the supercharging pressure based on at least a change mode of the supercharging pressure deviation epimdlt between the target supercharging pressure epimtrg and the actual supercharging pressure epim. For this reason, the presence or absence of a transient state can be determined even if there is a variation in the actual supercharging pressure epim due to a machine difference of the variable nozzle turbocharger 15 or a change with time.

  (2) The rate of change epimddlt of the supercharging pressure deviation epimdlt, which is the amount of change per hour with respect to the supercharging pressure deviation epimdlt, is used as a change mode of the supercharging pressure deviation epimdlt. If the supercharging pressure deviation epimdlt does not change much, the change rate epidimdlt should fluctuate around “0”. Therefore, by using this change rate epidimdlt, it is possible to accurately determine whether the supercharging pressure is stable or changing (in a transient state).

  (3) Although related to (2) above, when the rate of change epimddlt of the supercharging pressure deviation epimdlt is within the range R1, the supercharging pressure deviation between the target supercharging pressure epimtrg and the actual supercharging pressure epim The epimdlt does not change so much, and it can be said that the actual supercharging pressure epim is stable. On the other hand, if the rate of change epimddlt is out of the predetermined range, it can be said that the supercharging pressure deviation epimdlt fluctuates relatively greatly and the actual supercharging pressure epim is in a transient state.

  In this regard, according to the present embodiment, when the change rate epidimdlt is out of the range R1, it is determined that the state is in a transient state. Therefore, by setting the lower limit value EPIMDDIDW and the upper limit value EPIMDDIUP of the range R1 to appropriate values, it is determined whether the change rate epidimdlt is within the range R1 or not. It is possible to reliably determine whether or not.

  (4) When it is determined in the above (1) to (3) that the state is a transient state, the update of the integral term epvnpmi (i) is prohibited, thereby suppressing the increase of the feedback term epvnpmfb in the feedback control, Therefore, feedback control is suppressed. Therefore, even if a supercharging delay occurs in a transient state such as during acceleration and the actual supercharging pressure epim is significantly lower than the target supercharging pressure epimtrg, the variation in supercharging pressure due to machine differences is absorbed, The feedback control can reliably suppress the overshoot of the supercharging pressure.

  As a result, troubles due to overshooting of the supercharging pressure such as disconnection of the intake system hose, damage to the intercooler, damage to the impeller due to turbine over-rotation, etc., or damage to the engine body by increasing the cylinder pressure Can be resolved. A decrease in reliability of each part of the engine 11 including the variable nozzle turbocharger 15 can be suppressed.

  (5) Since the integration term epvnpmi is relieved from erroneous updating (learning) as described above, the nozzle vane 23 is rotated to the open side in order to suppress overshoot of the supercharging pressure (the nozzle opening is increased). ) No need. As a result, adaptation with priority given to supercharging response becomes possible, and acceleration response of the vehicle can be improved.

Note that the present invention can be embodied in another embodiment described below.
In the above embodiment, the lower limit value EPIMDDIDW and the upper limit value EPIMDDIUP of the range R1 are set to “−0.5” and “+0.5”, respectively, but this is only an example and can be changed as appropriate.

  As the integral term update prohibition condition, (vii) it is essential that the rate of change epimddlt is outside the predetermined range R1, but the other (i) to (vi) may be omitted as appropriate. Still another requirement may be added.

  The present invention is also applicable to an exhaust driving supercharger (turbocharger) having a supercharging pressure varying means other than a variable nozzle mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the structure about one Embodiment of the supercharging pressure control apparatus which actualized this invention. The front view of a variable nozzle mechanism. XX sectional drawing of FIG. The elements on larger scale which show a mode that the opening-and-closing lever of a variable nozzle mechanism is abutted against a stopper. The flowchart which shows the procedure which calculates an integral term. The time chart which shows the effect | action of a supercharging pressure control apparatus. The time chart which shows the effect | action of the supercharging pressure control apparatus when a rate of change is not included in integral term update prohibition conditions (comparative example).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 15 ... Variable nozzle turbocharger (exhaust drive type supercharger), 19 ... Variable nozzle mechanism (supercharging pressure variable means), 41 ... Engine ECU (supercharging pressure control means, transient state determination means, feedback control) Suppression means), epvnpmfb ... feedback term, epvnpmi (i-1), epvnpmi (i) ... integral term, epimtrg ... target supercharging pressure, epim ... actual supercharging pressure, epimdt ... supercharging pressure deviation, epimddlt ... change rate ( Change mode of supercharging pressure deviation), R1... Range.

Claims (5)

Used in an exhaust-driven supercharger having a supercharging pressure varying means, and the supercharging pressure can be varied so that the actual supercharging pressure by the exhaust-driven supercharger approaches a target supercharging pressure according to the operating state of the engine. In a supercharging pressure control device comprising a supercharging pressure control means for feedback control of the operation amount of the means,
A transient state determining means for determining a transient state of the boost pressure based on at least a change mode of a deviation between the target boost pressure and the actual boost pressure;
A supercharging pressure control device comprising feedback control suppression means for suppressing feedback control by the supercharging pressure control means in response to a transient determination by the transient state determination means. The supercharging pressure control apparatus according to claim 1, wherein the transient state determination means determines a transient state with respect to a supercharging pressure by using a change rate, which is a change amount of the deviation per time, as a change mode of the deviation. The supercharging pressure control device according to claim 2, wherein the transient state determining means determines that the state is in a transient state when the change rate of the deviation is out of a predetermined range. The supercharging according to any one of claims 1 to 3, wherein the feedback control suppression unit suppresses the feedback control by suppressing an increase in a feedback term in the feedback control according to a transient determination by the transient state determination unit. Pressure control device. The feedback term includes an integral term that is stored and updated in accordance with a deviation between the target boost pressure and the actual boost pressure,
The supercharging according to any one of claims 1 to 4, wherein the feedback control suppressing unit suppresses an increase in the feedback term by prohibiting the update of the integral term in accordance with a transient determination by the transient state determining unit. Pressure control device.

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