JP2009041469A - Turbocharger control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire a target intake air amount in a large exhaust pressure region, even in a turbo supercharger having a link mechanism linking a pressure actuator with a variable nozzle. <P>SOLUTION: A control device for a turbo supercharger comprises: the turbo supercharger having the link mechanism linking the pressure actuator with the variable nozzle; a means for determining whether or not a change direction of an operation target value of the supercharger is in an increasing direction or in a decreasing direction; and a means for converting the operation target value into a control instruction value, corresponding to an actuator hysteresis different in control instruction value according to the change direction of the operation target value. An engine control unit 42 includes a means for correcting the operation target value so that the operation target value becomes larger than an actuator drive amount corresponding to the actuator hysteresis for a predetermined time in the operation in the other direction after defining one operating direction out of two operating directions of a closing side and an opening side of the variable nozzle as a reference operating direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a variable capacity turbocharger.

A turbocharger having a pressure actuator (actuator that responds to supply of pressure according to a control command value) is a control target, and the target operation value of the turbocharger increases or decreases. From the result of this determination, there is hysteresis in the pressure actuator by making the control command value given to the pressure actuator different between the increase direction and the decrease direction even if the target operation value of the turbocharger is the same. However, there is one that can obtain an operation target value of a supercharger regardless of which direction the pressure actuator is driven (see Patent Document 1).
JP 2001-132463 A

  By the way, in other words, the hysteresis of the pressure actuator refers to a phenomenon in which the control command value (duty value) given to the pressure actuator differs depending on the change direction of the operation target value of the turbocharger. When the hysteresis of this pressure actuator is adapted in a region where the exhaust flow rate is small, if the exhaust pressure or exhaust flow rate is large, the target intake air amount (target supercharging pressure) expected from the operation target value of the turbocharger ) Was newly found out.

  Therefore, when an analysis was performed using an experimental method, the hysteresis of the pressure actuator changed due to the influence of the exhaust state, and the cause seems to be the play of the link mechanism that connects the pressure actuator and the variable nozzle. I found out.

  Therefore, the present invention provides a target intake air amount (target boost pressure) in a region where the exhaust pressure and the exhaust flow rate are large even in a turbocharger including a link mechanism that connects a pressure actuator and a variable nozzle. Objective.

  The present invention relates to a variable nozzle that adjusts the flow rate or flow velocity of exhaust gas flowing into an exhaust turbine, an actuator that responds to supply of pressure according to a control command value, and a link mechanism that connects the actuator and the variable nozzle. The turbocharger has a turbocharger, and sets an operation target value of the turbocharger, determines whether the change direction of the operation target value is an increase direction or a decrease direction, and changes the operation target value In the turbocharger control device that converts the operation target value into the control command value corresponding to the actuator hysteresis whose control command value differs depending on the direction, the variable nozzle closing side or opening side 2 One of the two operation directions is set as a reference operation direction in advance, and the actuator hysteresis is determined for a predetermined time during operation in the other direction. Correcting the operation target value to be larger than the actuator drive amount when corresponding to the scan.

  According to the present invention, either one of the two movement directions of the variable nozzle on the closing side or the opening side is determined in advance as a reference operation direction, and the actuator hysteresis is set to the actuator hysteresis for a predetermined time during the operation in the other direction. The turbocharger operation target value is corrected so that it is larger than the actuator drive amount in the corresponding case, so the response of the variable nozzle in the other direction is better than the current state, and the variable nozzle can be used in areas where exhaust pressure and exhaust flow are large. The hysteresis of the actuator does not change under these influences during operation in the other direction. Accordingly, the target intake air amount (target boost pressure) can be obtained even when the variable nozzle 53 operates in the other direction, and the control accuracy to the target intake air amount can be improved.

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

  FIG. 1 shows a schematic configuration when a turbocharger control device is applied to a diesel engine.

  In this engine, so-called low-temperature premixed combustion, in which the heat generation pattern is single-stage combustion, is performed. The generation of NOx greatly depends on the combustion temperature, and lowering the combustion temperature is effective for reducing it. In low-temperature premixed combustion, in order to realize low-temperature combustion by reducing the oxygen concentration by EGR, the EGR passage 4 connecting the exhaust passage 2 and the collector portion 3a of the intake passage 3 is responsive to the control pressure from the pressure control valve 5. A diaphragm type EGR valve 6 is provided.

  The pressure control valve 5 is driven by a duty control signal from the control unit 41, and thereby obtains a predetermined EGR rate corresponding to operating conditions. For example, the EGR rate is set to a maximum of 100 percent in the low rotation speed and low load range, and the EGR rate is decreased as the rotation speed and load increase. Since the exhaust gas temperature rises on the high load side, if a large amount of EGR gas is recirculated, the effect of NOx reduction is reduced due to the rise of the intake air temperature, or the ignition delay period of the injected fuel is shortened and premixed combustion cannot be realized. For this reason, the EGR rate is gradually reduced.

  An EGR gas cooling device 7 is provided in the middle of the EGR passage 4. This is because of a water jacket 8 formed around the EGR passage 4 in which a part of the engine cooling water is circulated, and a flow rate control valve 9 provided at the cooling water inlet 7a and capable of adjusting the circulation amount of the cooling water. Thus, the degree of cooling of the EGR gas increases as the amount of circulation increases through the control valve 9 according to a command from the control unit 41.

  A swirl control valve (not shown) having a predetermined notch is provided in the intake passage near the intake port to promote combustion. When the swirl control valve is closed by the control unit 41 in the low rotation speed and low load range, the flow rate of the intake air sucked into the combustion chamber increases and swirls are generated in the combustion chamber.

  The combustion chamber is a large-diameter toroidal combustion chamber (not shown). This is because the piston cavity is formed in a cylindrical shape from the crown to the bottom of the piston without restricting the inlet, and at the center of the bottom, resistance is given to the swirl that swirls from the outside of the piston cavity in the latter half of the compression stroke. In order to further improve the mixing of air and fuel, a conical portion is formed. Due to the cylindrical piston cavity that does not restrict the inlet, the swirl generated by the swirl valve or the like is diffused from the inside of the piston cavity to the outside of the cavity as the piston descends during the combustion process. The swirl is sustained.

  The engine includes a common rail fuel injection device 10. This fuel injection device 10 mainly comprises a fuel tank, a fuel supply passage, a supply pump 14, a common rail (accumulation chamber) 16, and a nozzle 17 provided for each cylinder. The fuel pressurized by the supply pump 14 is supplied to the fuel supply passage. Then, the high pressure fuel in the pressure accumulation chamber 16 is distributed to the nozzles 17 corresponding to the number of cylinders. If the fuel injection start time is adjusted by the switching timing of the three-way valve 25 provided in the nozzle 17 from OFF to ON, and the fuel injection amount is adjusted by the ON time, and the pressure in the pressure accumulating chamber 16 is the same, the ON time The fuel injection amount increases as the length increases.

  The fuel injection device 10 is further provided with a pressure adjusting valve in a passage for returning the fuel discharged from the supply pump 14 in order to adjust the pressure in the accumulator chamber. This regulating valve opens and closes the flow path of the passage, and adjusts the pressure in the pressure accumulation chamber by adjusting the amount of fuel discharged to the pressure accumulation chamber 16. The fuel injection rate varies depending on the fuel pressure (injection pressure) in the pressure accumulating chamber 16, and the fuel injection rate increases as the fuel pressure in the pressure accumulating chamber 16 increases.

  An accelerator opening sensor 33, a sensor 34 for detecting the engine speed and crank angle, a sensor 35 for cylinder discrimination, and a control unit 41 to which signals from the water temperature sensor 36 are input correspond to the engine speed and the accelerator opening. The target fuel injection amount and the target pressure of the pressure accumulating chamber 16 are calculated, and the fuel pressure in the pressure accumulating chamber 16 is fed back via the pressure adjusting valve so that the pressure accumulating chamber pressure detected by the pressure sensor matches the target pressure. Control.

  Further, in addition to controlling the ON time of the three-way valve 25 in accordance with the calculated target fuel injection amount, by controlling the switching time of the three-way valve 25 to ON, a predetermined injection start time corresponding to the operating condition is obtained. I am doing so. For example, the fuel injection timing (injection start timing) is delayed to the piston top dead center (TDC) so that the ignition delay period of the injected fuel becomes longer on the low rotation speed and low load side with a high EGR rate. By this delay, the temperature in the combustion chamber at the ignition timing is lowered, and the premixed combustion ratio is increased, thereby suppressing the occurrence of smoke in the high EGR rate region. On the other hand, the injection timing is advanced as the rotational speed and load increase. This is because even if the ignition delay time is constant, the ignition delay crank angle (the value obtained by converting the ignition delay time into a crank angle) increases in proportion to the increase in the engine rotation speed. The injection timing is advanced in order to obtain the ignition timing.

  Returning to FIG. 1, a variable capacity turbocharger is provided in the exhaust passage 2 downstream of the opening of the EGR passage 4. This is because a variable nozzle 53 driven by a pressure actuator 54 is provided at the scroll inlet of the exhaust turbine 52, so that the control unit 41 can obtain a predetermined supercharging pressure from the low rotational speed range by the control unit 41. Further, the nozzle opening (in a tilted state) that increases the flow rate of the exhaust gas introduced into the exhaust turbine 52 on the low rotation speed side, and the exhaust opening is introduced into the exhaust turbine 52 without resistance on the high rotation speed side (nozzle opening state). To control.

  The pressure actuator 54 includes a diaphragm actuator 55 that drives the variable nozzle 53 in response to the control pressure, and a pressure control valve 56 that adjusts the control pressure to the actuator 55. The opening ratio of the variable nozzle 53 is as follows. A duty control signal (control command value) is generated so as to achieve the target opening ratio TRTO, and this duty control signal is output to the pressure control valve 56.

  At present, in order to compensate for the dynamics of the pressure actuator 54, particularly the diaphragm actuator 55, an advance process is performed on the target opening ratio TRTO of the variable nozzle 53 to obtain the feedforward amount of the target opening ratio, A value obtained by adding the feedback amount of the ratio is calculated as a command opening ratio Avnt, and by searching the linearization table for the command opening ratio Avnt, a command opening ratio linearization processing value Ratdty is set as a duty value. Hysteresis processing is performed on the aperture ratio linearization processing value Ratdty. This hysteresis processing is processing corresponding to the hysteresis characteristics of the actuator.

  Here, the hysteresis characteristics of the actuator will be described with reference to FIG. 2. In FIG. 2, the horizontal axis represents the control command value (duty value) [%] given to the pressure control valve 56, and the vertical axis represents the lift of the diaphragm actuator 55. It is a ratio [%] (the ratio of the lift amount at that time to the maximum lift amount of the rod 56 in FIG. 1). FIG. 2 shows that when the actuator lift ratio for the same duty value is compared, the variable nozzle 53 is larger in the operation direction of the variable nozzle 53 than in the closed side. Thus, the hysteresis of the actuator 55 refers to a phenomenon in which the control command value (duty value) given to the pressure control valve 56 differs depending on the operation direction of the variable nozzle 53 (the change direction of the operation target value of the supercharger). It is.

  In addition, although the control negative pressure introduced into the diaphragm chamber 55a is made by diluting in the atmosphere with respect to the constant negative pressure (pressure lower than the atmospheric pressure) from the vacuum pump, the dilution ratio of the atmosphere is maximum ( When the duty value is, for example, 0%), that is, when the atmosphere is introduced as it is into the diaphragm chamber 55a, the actuator lift ratio is zero. If the dilution ratio of the atmosphere is decreased from this state, the diaphragm 55b lifts the rod 55d upward in FIG. 1 against the diaphragm spring 55c. Accordingly, when the atmospheric dilution ratio is the minimum (for example, the duty value is 100%), that is, when the constant negative pressure from the vacuum pump is introduced as it is into the diaphragm chamber 55a, the rod 55d is lifted to the maximum position, and the actuator lift The ratio is maximum.

  However, subsequent experiments have revealed that an error from the target intake air amount occurs in a region where the exhaust pressure is high. This will be described with reference to FIG. 3. In FIG. 3, the horizontal axis represents the control command value (duty value) [%] given to the same pressure control valve 56 as in FIG. 1, and the vertical axis represents the intake air amount [mg / st]. As shown in FIG. 3, when the operation direction of the variable nozzle 53 is the open side, the difference in the intake air amount from the case where the operation direction of the variable nozzle 53 is the close side particularly in a region where the exhaust pressure is high is large. Has occurred. Assuming that the sensitivity of the intake air at the time of the actuator lift is the same for both the opening and closing directions of the variable nozzle 53, a square plot and a triangular plot are shown as shown in FIG. Should be hysteresis. However, in actuality, in the region where the operating direction of the variable nozzle 53 is the open side and the exhaust pressure is large, the behavior of the plot indicated by ● shows the difference between the plot of ● and the triangular plot, which is the effect of the exhaust pressure. As a result, the hysteresis increases (see FIG. 5). FIG. 5 is an enlarged view of a part of FIG.

Such an increase in hysteresis was not expected in the current control, that is, the phenomenon shown in FIGS. 3 and 4 was first found by the present inventor. The reason why such a phenomenon occurs is that the variable nozzle 53 is connected to the rod 55d that moves in the vertical direction in FIG. 1 via the link mechanism 55e, and the link mechanism that connects the rod 55d and the variable nozzle 53. The present inventor has inferred that the operation of the variable nozzle 53 is affected by the play of 55e in a region where the exhaust pressure is large. Therefore, in addition to the actuator hysteresis, it can be seen that a new correction is necessary to eliminate the increase in hysteresis affected by the exhaust pressure. FIG. 6 shows the exhaust pressure [kPa] on the horizontal axis and the vertical axis on the vertical axis. In FIG. 4, the difference between the ● value and the triangular value for the same duty value is taken as the numerator and the value ● is taken as the denominator. That is, the vertical axis represents the deviation of the intake air amount from the triangular plot in FIG. 4 (the increase in hysteresis affected by the exhaust pressure). From FIG. 6, it can be seen that the increase in hysteresis affected by the exhaust pressure is affected by the exhaust pressure at that time and the lift amount of the actuator 55.

  Here, referring to FIG. 4 again, when the operation on the opening side of the variable nozzle 53 is considered, the variable nozzle 53 is driven back by the large exhaust pressure in the region where the exhaust pressure is large. The amount is reduced by the amount of play of the link mechanism 55e. That is, the response of the opening side operation of the variable nozzle 53 is delayed by the amount of play of the link mechanism 55e, and the amount of intake air increases with the response delay. In other words, if the variable nozzle 53 is operated responsively on the open side by following a triangular plot, the target intake air amount should be obtained, but the open side of the variable nozzle 53 is affected by the exhaust pressure. Since the response delay occurs in the operation, the plot of ● is followed, and the intake air amount increases outside the target intake air amount. Therefore, in order to reduce the amount of intake air from the plot ● in FIG. 4 to the triangular plot, the response of the opening side operation of the variable nozzle 53 may be increased.

  Therefore, in the present invention, when the closing side of the variable nozzle 53 is set as a reference operation direction, the operation amount to the opening side of the variable nozzle 53 is larger than the actuator driving amount corresponding to the actuator hysteresis for a predetermined time. The target opening ratio TRTO (operation target value) of the variable nozzle 53 is corrected. At that time, the control accuracy to the target intake air amount is improved by calculating the correction amount of the target opening ratio TRTO and the predetermined time according to the exhaust pressure (exhaust state) and the lift amount of the actuator.

  2 to 6, the closing side of the two operating directions of the variable nozzle 53 on the closing side or opening side is defined as the reference operating direction, but the present invention is not limited to this. When the opening side of the variable nozzle 53 is determined as the reference operation direction, it is considered that a hysteresis change affected by the exhaust pressure occurs even in the closed side and in the region where the exhaust pressure is large. Accordingly, even in this case, the target opening ratio TRTO (operation target value) of the variable nozzle 53 is corrected to the side where the hysteresis change is eliminated depending on whether the hysteresis change is an increase or decrease. Good.

  This control executed by the engine control unit 41 will be described in detail based on the following flowchart.

  FIG. 7 is for calculating a control command value (duty value) to be applied to the pressure control valve 56, and is executed at regular intervals (for example, every 10 msec).

  In step 1, various signals are read.

  In step 2, a target opening ratio TRTO (operation target value of the supercharger) of the variable nozzle 53 is calculated. Here, the opening ratio of the variable nozzle 53 is the ratio of the current nozzle area to the nozzle area when the variable nozzle 53 is fully opened. Therefore, the opening ratio is 100% when the variable nozzle 53 is fully opened, and the opening ratio is 0% when the variable nozzle 53 is fully closed. The reason for adopting the opening ratio of the variable nozzle 53 instead of the opening area itself of the variable nozzle 53 is to provide versatility (a value not related to the capacity of the turbocharger). Of course, the opening area of the variable nozzle 53 may be adopted. The turbocharger of the embodiment is of a type in which the supercharging pressure is the smallest when the variable nozzle is fully opened and the supercharging pressure is the highest when the variable nozzle is fully closed. Increases supercharging pressure.

The target opening ratio of the variable nozzle 53 is set so that the target intake air amount tQac corresponding to the operating conditions can be obtained. A method for calculating the target opening ratio of the variable nozzle 53 is known from Japanese Patent Application Laid-Open No. 2001-132463. Briefly, from the target intake air amount tQac, the actual EGR amount Qec, the engine speed Ne, and the target fuel injection amount Qsol,
tQas0 = (tQac + Qsol × QFGAN #) × Ne / KCON #
... (1)
Qes0 = (Qec + Qsol × QFGAN #) × Ne / KCON #
... (2)
Where Qsol: target fuel injection amount,
QFGAN #: Gain,
KCON #: constant,
In the same manner, the intake air amount equivalent value tQas0 (set intake air amount equivalent value) for setting the target opening ratio is equivalent to the EGR amount equivalent value Qes0 (set EGR amount equivalent value) for setting the target opening ratio. And the target opening ratio TRTO of the variable nozzle 53 is set by searching a predetermined map from the set intake air amount equivalent value tQas0 and the set EGR amount equivalent value tQes0. In equations (1) and (2), Qsol × QFGAN # is added to the target intake air amount tQac and the actual EGR amount Qec because the load corresponds to the set intake air amount equivalent value and the set EGR amount equivalent value. The correction can be performed and the sensitivity is adjusted by the gain QFGAN #. Further, Ne / KCON # is a value for converting into an intake air amount and an EGR amount per unit time.

  The target intake air amount tQac is divided into an EGR operating range and an EGR non-operating range. In the EGR operating range, the EGR non-operating range basically corresponds to the actual EGR rate Megrd and the engine speed Ne. Is calculated according to the target fuel injection amount Qsol and the engine speed Ne.

  Alternatively, the set intake air amount equivalent value tQas0 is calculated from the target intake air amount tQac, the actual EGR rate Megrd, the engine speed Ne, and the target fuel injection amount Qsol by the above equation (1), and this set intake air amount equivalent value tQas0 is obtained. The target opening ratio TRTO of the variable nozzle 53 is set by searching a predetermined map from the actual EGR rate Megard.

In step 3, the opening direction flag DIR of the variable nozzle 23 based on the target opening ratio TRTO of the variable nozzle 53. Set TRTO. This opening operation direction flag DIR The setting of TRTO will be described with reference to the flow of FIG. 8 (subroutine of step 3 in FIG. 7). In FIG. 8, in step 101, the target opening ratio TRTO and the time constant equivalent value Tcrto are read, and from these, in step 102,
TRTOdly = TRTO × Tcrto + TRTOdly _n−1 × (1-Tcrto)
... (3)
However, TRTOdly _n-1 : last TRTOdly,
The expected opening ratio TRTOdly is calculated by the following formula, and this value is compared with TRTOdly _nM , which is the previous value M (where M is a constant) times of the previous expected opening ratio, in step 103.

When TRTOdly ≧ TRTOdly _nM (when the target opening ratio is increasing or steady), the routine proceeds to step 104 to indicate that the target opening ratio is increasing or steady, and the operation direction flag fvnt = 1. Otherwise, the routine proceeds to step 105 where the operation direction flag fvnt = 0. Further, in order to separate the case where the target opening ratio is increasing and the steady state, TRTOdly and TRTOdly _nM are compared in step 106. If TRTOdly = TRTOdly _nM , the process proceeds to step 107 and the holding flag fvnt2 = 1 is set. Otherwise, the holding flag fvnt2 = 0 is set at step 108.

Since the operation direction of the variable nozzle 53 can be known from the two flags fvnt and fvnt2 set in this way, in step 109, the two flags fvnt and fvnt2 are tried again. When fvnt = 1 and fvnt2 = 0 (the target opening ratio tends to increase), it is determined that the operation direction of the variable nozzle 53 is the open side, and the routine proceeds to step 110 where the open operation direction flag DIR is reached. If TRTO = OPEN, otherwise proceed to step 111 and open operation direction flag DIR TRTO = CLOSE.

This completes the subroutine of FIG. 8, so that the processing returns to FIG. 7, and in step 4, the opening operation direction flag DIR set in FIG. Watch TRTO. Opening direction flag DIR When TRTO = OPEN, that is, when the operation direction of the variable nozzle 53 is the open side, the process proceeds to step 5 to predict the actual exhaust state. Prediction of the exhaust state will be described with reference to the flowchart of FIG. 9 (subroutine of step 5 in FIG. 7).

  9, in step 201, the cylinder intake air amount Qac [mg / t], the target fuel injection amount Qsol [mg / t], and the engine rotational speed Ne [rpm] are read. In step 202, the exhaust flow rate QEXH [mg] is calculated by the following equation. / S] is calculated.

QEXH = (Qac + Qsol) × Ne / (120,000 × CYL)
(4)
Where CYL: number of cylinders
The calculation method of the cylinder intake air amount Qac and the target fuel injection amount Qsol is known from Japanese Patent Laid-Open No. 2001-132463. Here, the cylinder intake air amount Qac is a value corresponding to an actual value for the target intake air amount tQac.

  Although FIG. 9 shows a case where the exhaust flow rate QEXH is calculated as an actual exhaust state, the exhaust pressure PEXH may be used instead. What is necessary is just to detect with a pressure sensor, when employ | adopting exhaust pressure.

In step 203, the actuator lift amount (lift amount of the rod 55d) LIFT detected by the lift sensor 37 provided in the diaphragm actuator 55 Read ACT.

In step 204, from the target opening ratio TRTO and the time constant equivalent value Tcrto,
RRTO = TRTO × Tcrto + RRTO _n−1 × (1-Tcrto)
... (5)
However, RRTO _n-1 : previous RRTO,
The actual opening ratio RRTO of the variable nozzle 53 is calculated by performing a delay process according to the following equation.

The actuator lift amount (lift amount of the rod 55d) LIFT detected by the lift sensor 37 The opening ratio of the variable nozzle 53 may be obtained by searching a predetermined table from the ACT, and the obtained value may be used as the actual opening ratio RRTO of the variable nozzle 53.

  This completes the subroutine of FIG. 9 and returns to FIG.

  Steps 6 and 7 in FIG. 7 are parts for performing advance processing on the actual opening ratio RRTO of the variable nozzle 53 so that an increase in hysteresis affected by the exhaust pressure does not occur. However, in this embodiment, the advance process is performed on the actual opening ratio RRTO of the variable nozzle 53, but the advance process may be simply performed on the target opening ratio TRTO of the variable nozzle 53.

The advance process itself in steps 6 and 7 is basically the same as the advance process shown in steps 8 and 9 described later. First, in step 6, the advance gain GPREEX and the time constant equivalent value TCPREEX are calculated. That is, the advance gain basic value GPREEX is obtained by searching a table having the contents shown in FIG. 10 from the exhaust flow rate QEXH calculated in FIG. BASE and the actuator lift amount LIFT calculated in FIG. The advance gain correction amount GPREEX is obtained by searching the table having the contents shown in FIG. 11 from the ACT. By calculating HOS and multiplying these two values, that is, the advance gain GPREEX is calculated by the following equation.

GPREEX = GPREEX BASE x GPREEX HOS
(6)
Further, a time constant equivalent value basic value TCPREEX is obtained by searching a table having the contents shown in FIG. 12 from the exhaust flow rate QEXH calculated in FIG. BASE and the actuator lift amount LIFT calculated in FIG. A time constant equivalent value correction amount TCPREEX is obtained by searching a table having the contents shown in FIG. 13 from ACT. By calculating HOS and multiplying these two values, that is, the time constant equivalent value TCPREEX is calculated by the following equation. However, the time constant equivalent value TCPREEX is limited to a range of 0 <TCPREEX ≦ 1.

TCPREEX = TCPREEX BASE × TCPREEX HOS
... (7)
As shown in FIG. 10, the advance gain basic value GPREEX increases as the exhaust gas flow rate QEXH increases. The reason why the BASE is increased is that the response delay of the diaphragm actuator 55 increases as the exhaust flow rate QEXH increases, and accordingly, it is necessary to increase the advance correction gain accordingly. As shown in FIG. 11, the actuator lift amount LIFT Gain correction amount GPREEX with ACT at medium value The HOS is increased in accordance with the characteristics shown in FIG.

As shown in FIG. 12, the time constant basic value TCPREEX increases as the exhaust flow rate QEXH increases. The reason why the BASE is reduced is that the response delay of the diaphragm actuator 55 increases as the exhaust flow rate QEXH increases (the time constant increases, and the time constant corresponding to the inverse of the time constant decreases). It is a combination. As shown in FIG. 13, the lift amount LIFT ACT is a medium value and time constant equivalent value correction amount TCPREEX The reason why the HOS is reduced is also in accordance with the characteristics shown in FIG.

  10 and 12, the exhaust pressure PEXH can be taken on the horizontal axis.

In step 7, using the time constant equivalent value TCPREEX thus obtained and the actual aperture ratio RRTO calculated in FIG. 9,
Carto1 = RRTOR × TCPREEX
+ Carto1 _n-1 × (1-TCPREEX)
... (8)
However, Carto1 _n-1 : Previous Carto1,
The first predicted opening ratio Carto1 is calculated by the following equation, and from this value, the actual opening ratio RRTO, and the advance gain GPREEX,
RRTO f1 = GPREEX × RRTO
− (GPREEX-1) × Carto1 _n−1 ,
... (9)
However, Carto1 _n-1 : Previous Carto1,
The first feedforward amount RRTO of the actual opening ratio is processed by the following formula Calculate f1. In order to calculate the equations (8) and (9), for example, a block diagram with a simple configuration as shown in FIGS. 14 and 15 may be assembled. Then, the process proceeds to Step 8.

On the other hand, in step 4, the opening operation direction flag DIR When TRTO = CLOSE, that is, when the operation direction of the variable nozzle 53 is the closing side, Steps 5, 6, and 7 are skipped and the process proceeds to Step 8.

Steps 8 and 9 are the same as the current control. That is, the steps 8 and 9 are the first feedforward amount TRTO of the actual opening ratio thus obtained. This is a part that performs advance processing to compensate for the dynamics of the diaphragm actuator 55 with respect to f1. This is because the diaphragm actuator 55 is an actuator that is driven by receiving pressure supplied in accordance with the control command value, and therefore there is a response delay that cannot be ignored unlike the step motor.

First, at step 8, the advance gain GPRE and the time constant equivalent value TCPRE are calculated. That is, the opening direction flag DIR The advance gain GPRE and the time constant equivalent value TCPRE (0 <TCPRE ≦ 1) are calculated by searching the tables having the contents shown in FIGS. 16 and 17 from the TRTO. As shown in FIGS. 16 and 17, the advance gain GPRE and the time constant equivalent value TCPRE are made different depending on whether the operation direction of the variable nozzle 53 is the open side or the close side, and the open side is the close side. The value is made smaller. This is because it is necessary to resist the exhaust pressure when the operation direction of the variable nozzle 53 is on the closed side, so that the gain is increased by that amount and the time constant is reduced (corresponding to a time constant that is in a relationship inverse to the time constant) This is because the value needs to be increased).

In step 9, the time constant equivalent value TCPRE thus obtained and the first feedforward amount TRTO of the actual aperture ratio are obtained. Using f1,
Carto2 = TRTO f1 × TCPRE
+ Carto2 _n-1 × (1-TCPRE)
(10)
However, Carto2 _n-1 : Previous Carto2,
The second predicted opening ratio Carto2 is calculated by the following formula, and this value and the first feedforward amount RRTO of the actual opening ratio are calculated. From f1 and the gain GPRE,
RRTO f2 = GPRE × RRTO f1
-(GPRE-1) x Carto2n _-1 ,
... (11)
However, Carto2 _n-1 : Previous Carto2,
The second feedforward amount RRTO of the actual opening ratio is processed by the following formula f2 is calculated. In order to calculate the expressions (10) and (11), for example, a block diagram with a simple configuration as shown in FIGS.

In Step 10, the second feedforward amount RRTO of the actual opening ratio thus obtained is obtained. f2 is converted into a control command value (duty value) given to the pressure control valve 56. At that time, hysteresis processing is performed using FIG. That is, the above opening operation direction flag DIR The operation direction of the variable nozzle 53 is determined using TRTO, and when the operation direction of the variable nozzle 53 is the open side, it is converted into a control command value with reference to the characteristics indicated by ●, and the variable nozzle 53 When the operation direction is the closed side, the control command value is converted with reference to the characteristics indicated by □. Thus, the second feedforward amount RRTO of the actual opening ratio corresponding to the hysteresis of the actuator 55 whose control command value differs depending on the operation direction of the variable nozzle 53 (change direction of the operation target value). f2 (operation target value) is converted into a control command value.

  A duty signal is generated from the control command value obtained in this way and output to the pressure control valve 56.

  Here, the effect of this embodiment is demonstrated.

  According to this embodiment (the invention described in claim 1), the operation direction on the closing side of the variable nozzle 53 is determined as the reference operation direction, and the actuator 55 is operated for a predetermined time during the operation on the opening side (other direction). Since the actual opening ratio RRTO (operation target value of the supercharger) of the variable nozzle 53 is corrected so as to be larger than the actuator driving amount in the case of corresponding to the hysteresis of (see steps 4, 5, 6, and 7 in FIG. 7). ) The response of the opening operation of the variable nozzle 53 becomes better than the current state, and the hysteresis of the actuator 55 increases (changes) due to the influence of the exhaust flow rate QEXH during the operation of the variable nozzle 53 in the region where the exhaust flow rate QEXH is large. There is no. Therefore, the target intake air amount tQac (target boost pressure) can be obtained even when the variable nozzle 53 is opened, and the control accuracy to the target intake air amount tQac can be improved.

  According to the present embodiment (the invention described in claim 2), the reference operation direction is the operation direction on the closing side of the variable nozzle 53, that is, the operation direction on the side where the influence of the exhaust state on the actuator driving amount is small. Therefore, it is possible to improve the air amount control accuracy in the operation direction that is greatly affected by the exhaust state.

According to the present embodiment (the invention according to claim 3), the advance gain GPREEX (correction amount of the operation target value of the turbocharger) and the time constant equivalent value TCPREEX (predetermined time) are set to the exhaust flow rate QEXH (exhaust state). And lift amount LIFT of actuator 55 Since the calculation is performed in accordance with ACT (actuation amount) (see FIGS. 10 to 13), the advance gain GPREEX (correction amount of the operation target value of the turbocharger) and the time constant equivalent value TCPREEX (predetermined time) are set to the exhaust flow rate QEXH. (Exhaust state) and lift amount LIFT of actuator 55 Regardless of ACT, it can be given without excess or deficiency.

According to the present embodiment (the invention described in claim 5), the advance gain basic value GPREEX increases as the exhaust gas flow rate QEXH increases. As the BASE (correction amount of the operation target value) is increased (see FIG. 10) and the exhaust flow rate QEXH is larger as shown in FIG. 12, the time constant equivalent value basic value TCPREEX Since the BASE is shortened (the time constant that is the reciprocal of the time constant equivalent value, that is, the predetermined time becomes longer), the influence of the exhaust state can be canceled regardless of the exhaust flow rate QEXH.

  According to the present embodiment (the invention described in claim 6), correction of the actual opening ratio RRTO (operation target value) is performed by advance processing, the correction amount of the operation target value is advanced, the gain GPPREEX, and the predetermined time corresponding to the time constant. Since it is controlled by the value TCPREEX (see Step 7, FIG. 14, FIG. 15 in FIG. 7), the correction of the operation target value can be realized with a simple logic configuration.

  The function of the operation target value setting means according to claim 1 is according to step 2 in FIG. 7, the function of the determination means is according to steps 3 and 4 in FIG. 7, and the function of the conversion means is according to step 10 in FIG. The function of the correcting means is performed by steps 6 and 7 in FIG.

The schematic block diagram of the control apparatus of the supercharger of 1st Embodiment of this invention. FIG. 6 is a characteristic diagram of actuator hysteresis. The characteristic diagram of hysteresis of intake air amount. The characteristic diagram of hysteresis of intake air amount. FIG. 5 is a partially enlarged view of FIG. 4. The characteristic view of the increase in actuator hysteresis with respect to the exhaust pressure. The flowchart for demonstrating the calculation of a control command value. The flowchart for demonstrating the setting of an open operation flag. The flowchart for demonstrating the prediction of an exhaust state. The characteristic diagram of the lead gain basic value with respect to the exhaust flow rate. The characteristic diagram of the advance gain correction amount with respect to the actuator lift amount. The characteristic figure of the time constant equivalent value basic value to the exhaust flow rate. The characteristic diagram of the time constant equivalent value correction amount with respect to the actuator lift amount. The block diagram of advance processing. Advance processing block diagram The characteristic figure of the advance gain with respect to an operation direction. The characteristic figure of the time constant equivalent value with respect to an operation direction. Advance processing block diagram Advance processing block diagram The characteristic view showing the relationship between an opening ratio and a control command value.

Explanation of symbols

37 Lift sensor 41 Engine control unit 53 Variable nozzle 54 Pressure actuator 55 Diaphragm actuator 55d Rod 55e Link mechanism 56 Pressure control valve

Claims (6)

A variable nozzle for adjusting the flow rate or flow velocity of the exhaust gas flowing into the exhaust turbine;
An actuator that responds to supply of pressure according to the control command value;
A turbocharger having a link mechanism connecting the actuator and the variable nozzle;
An operation target value setting means for setting the operation target value of the supercharger;
Determination means for determining whether the direction of change of the operation target value is an increase direction or a decrease direction;
In a turbocharger control device comprising: conversion means for converting the operation target value into the control command value in response to an actuator hysteresis in which the control command value varies depending on the change direction of the operation target value.
Actuator drive when one of the two operating directions of the variable nozzle on the closing side or on the opening side is determined as a reference operating direction, and the actuator hysteresis corresponds to the actuator hysteresis for a predetermined time when operating in the other direction. A turbocharger control device comprising: an operation target value correction unit that corrects the operation target value so as to be larger than an amount.   2. The turbocharger control device according to claim 1, wherein the reference operation direction is an operation direction on a side less influenced by an exhaust state with respect to an actuator driving amount.   The turbocharger control device according to claim 1, wherein the correction amount of the operation target value and the predetermined time are calculated according to the exhaust state and the operation amount of the actuator.   The turbocharger control device according to claim 3, wherein the exhaust state is one of an exhaust pressure and an exhaust flow rate.   The turbocharger control device according to claim 4, wherein the higher the exhaust pressure or the greater the exhaust flow rate, the larger the correction amount of the operation target value and the longer the predetermined time.   2. The turbocharger according to claim 1, wherein the operation target value correcting means is an advance processing means, and the correction amount of the operation target value is controlled by an advance gain and the predetermined time is controlled by a time constant equivalent value. Control device.