JP2010185415A - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide supercharging pressure control causing no the overshoot of supercharging pressure in acceleration. <P>SOLUTION: An engine controller 31 includes a means for computing a control target value of an EGR (exhaust gas recirculation) device; a means for controlling the EGR device to reach the control target value of the EGR device; a means for computing the control target value in the acceleration of a variable displacement supercharger as a value for making the decrease correction of the control target value at the stationary time of the variable displacement supercharger based on target supercharging pressure and actual supercharging pressure; a means for setting an operation target value of the variable displacement supercharger based on the control target value in the acceleration of the variable displacement supercharger and the control target value of the EGR device or the control actual value of the EGR device; and a means for controlling the variable displacement supercharger to attain the operation target value of the variable displacement supercharger. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine control device, and more particularly to control during acceleration of an engine provided with a variable capacity supercharger and an EGR device.

In a diesel engine equipped with a turbocharger having a variable nozzle and an EGR device, as a countermeasure at the time of acceleration, a product Pse of the engine rotational speed Ne and the target fuel injection amount Qsol is calculated, and this value and the previous product value the difference _{dPse (= Pse-Pse n-} 1) between the Pse _n-1 is calculated, and calculates a correction coefficient kRvnt opening percentage by searching a predetermined table from the difference DPSE, the correction coefficient kRvnt There is one that calculates a value obtained by multiplying a target opening ratio basic value as a target opening ratio Rvnt of a variable nozzle (see Patent Document 1).

JP 2001-123873 A

  By the way, even if the turbocharger variable nozzle is controlled so that the target supercharging pressure (or intake air amount) is obtained during acceleration, the actual supercharging pressure (actual intake air amount) does not rise immediately. The engine rises with a large delay from the target supercharging pressure (target intake air amount), and so-called supercharging pressure overshoot occurs. This is because even if the target boost pressure changes stepwise according to the movement of the accelerator pedal, this is an increase in turbine work → increase in compressor work → increase in actual boost pressure → increase in actual intake air amount This is because there is a large response delay before it appears. For this reason, there is a demand for avoiding such a delay in the response of the supercharging pressure in the early stage of acceleration and an overshoot of the supercharging pressure in the late stage of acceleration.

  However, a supercharging pressure control that does not cause an overshoot of the supercharging pressure during acceleration has not yet been disclosed. Although technology to prevent overcharging pressure overshoot has been proposed, such technology is not necessary in the first place if supercharging pressure can be controlled so that overshooting of the supercharging pressure itself does not occur. . In the technique of Patent Document 1 described above, the opening side correction of the opening ratio is limited to the initial stage of acceleration, and the countermeasure is only the delay in the rise of the supercharging pressure in the initial stage of acceleration. Not supported.

  Accordingly, an object of the present invention is to provide a supercharging pressure control that does not cause an overshoot of the supercharging pressure during acceleration.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes a variable capacity supercharger (21) and an EGR device (14), calculates a control target value of the EGR device according to operating conditions, and sets the EGR device so as to be the control target value of the EGR device. (14) is controlled, the target back pressure or the target supercharging pressure is calculated according to the operating conditions, the actual back pressure or the actual supercharging pressure is detected, and based on these target back pressure and actual back pressure Alternatively, based on the target supercharging pressure and the actual supercharging pressure, the variable capacity supercharger (21) is accelerated when the variable capacity supercharger (21) is accelerated as a value for reducing and correcting the steady-state control target value of the variable capacity supercharger (21). A control target value is calculated, and a variable capacity is determined based on the control target value at the time of acceleration of the variable capacity supercharger (21) and the control target value of the EGR device (14) or the control actual value of the EGR device (14). The operation target value of the supercharger (21) is set, and this variable capacity supercharger (21) Configured to control the variable capacity turbocharger (21) so that the operation target value.

  According to the present invention, a variable capacity supercharger and an EGR device are provided, a control target value of the EGR device is calculated according to operating conditions, and the EGR device is controlled to be the control target value of the EGR device, Calculate the target back pressure or the target boost pressure according to the operating conditions, detect the actual back pressure or the actual boost pressure, and based on the target back pressure and the actual back pressure or the target boost pressure and the actual boost pressure Based on the supercharging pressure of the variable capacity supercharger, the control target value at the time of acceleration of the variable capacity supercharger is calculated as a value for reducing and correcting the control target value at the steady state of the variable capacity supercharger. Based on the control target value at the time of acceleration and the control target value of the EGR device or the control actual value of the EGR device, the operation target value of the variable capacity supercharger is set, and becomes the operation target value of the variable capacity supercharger. So that the variable capacity turbocharger is controlled so that Becomes the control target value gives an optimum target intake air amount during acceleration overshoot of the supercharging pressure can be realized supercharging pressure control that does not cause the first place during acceleration.

It is a schematic block diagram of the engine control apparatus of 1st Embodiment of this invention. It is a block diagram of the engine control system of a 1st embodiment. It is a timing chart showing the change of the target intake air amount at the time of acceleration, intake air amount, the target opening ratio of a variable nozzle, and an actual opening ratio. It is a timing chart showing the change of the target supercharging pressure at the time of acceleration, an actual supercharging pressure, the target opening ratio of a variable nozzle, and an actual opening ratio. It is a block diagram of the supercharging pressure control of 1st Embodiment. FIG. 6 is a characteristic diagram of a target intake air amount. It is a characteristic figure of a target supercharging pressure. It is a characteristic view of a target intake air amount deviation. It is a characteristic view of a target opening ratio. It is a flowchart for demonstrating the calculation of the target opening ratio of 2nd Embodiment. It is a characteristic view of the target intake air amount for supercharger control of 2nd Embodiment. It is a characteristic figure of the target opening ratio of a 2nd embodiment. It is a flowchart for demonstrating the calculation of the target opening ratio of 3rd Embodiment. The gain characteristic figure of 3rd Embodiment.

  FIG. 1 is a schematic configuration diagram of a diesel engine control apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of an engine control system.

  1 and 2, the engine 1 includes a common rail fuel injection device 2. In the common rail fuel injection device 2, the fuel pressurized by the supply pump 3 is temporarily stored in the common rail 5 through the fuel supply passage 4, and then the high pressure fuel in the common rail 5 is distributed by the fuel injection valves 6 for the number of cylinders. Supplied. The fuel injection valve 6 has a three-way valve (solenoid valve) (not shown). When the three-way valve is OFF, the needle valve is in the seating state. Has come to jet. That is, if the fuel injection amount is adjusted by the ON time of the three-way valve and the pressure in the common rail 5 is the same, the fuel injection amount increases as the ON time becomes longer.

  From an accelerator opening sensor 32 (generates an output Cl proportional to the accelerator pedal depression amount), a crank angle sensor 33 (detects the engine speed and crank angle), a cam angle sensor 34 (performs cylinder discrimination), and a water temperature sensor 35 In the engine controller 31 to which the signal is input, the target fuel injection amount Qsol [mg / st] is calculated according to the engine speed Ne and the accelerator opening degree Cl, and the above three-way operation is performed corresponding to the calculated target fuel injection amount Qsol. Controls the valve ON time.

  The engine 1 includes an EGR device (exhaust gas) that includes an EGR passage 13 that recirculates part of the exhaust gas in the exhaust passage 12 to the intake passage 11 and an EGR valve 14 that adjusts the flow rate of exhaust gas (EGR gas) flowing through the EGR passage 13. A reflux apparatus). The lift amount of the EGR valve 14 is changed by the rotation of the step motor, the opening degree of the EGR valve 14 is adjusted, and the EGR gas flow rate is increased or decreased according to the opening degree of the EGR valve 14. Reference numeral 15 denotes an EGR cooler.

  A variable capacity turbocharger 21 (variable capacity supercharger) is provided in the exhaust passage 12 downstream of the opening of the EGR passage 13. This is provided with a variable nozzle 21d driven by a step motor 21c at a scroll inlet of an exhaust turbine 21b arranged coaxially with the intake compressor 21a. The variable nozzle 21d obtains a predetermined supercharging pressure from a low rotation range. As shown, the nozzle opening degree (tilting state) increases the flow rate of the exhaust gas introduced into the exhaust turbine 21b in the low rotation range, and the nozzle opening degree (full open state) causes the exhaust gas to be introduced into the exhaust turbine 21b without resistance on the high rotation side. Can be controlled. 22 is an intercooler.

  In this embodiment, the method of driving the nozzle opening of the variable nozzle 21d by the step motor 21c will be described. However, a method of driving the variable nozzle 21d by a diaphragm actuator and an electromagnetic solenoid that adjusts a control negative pressure to the diaphragm actuator is described. A method of driving the variable nozzle 21d with a DC motor may be used.

  When performing supercharging pressure control using the variable capacity turbocharger 21 and EGR control using the EGR valve 14 from the viewpoint of supercharging pressure control, EGR control also plays a role of supercharging pressure control. Is physically fulfilled. That is, the supercharging pressure is also changed by changing the EGR gas amount. On the contrary, when the supercharging pressure is changed, the exhaust pressure changes, so the EGR gas amount also changes, and the supercharging pressure and the EGR gas amount cannot be controlled independently. In addition, there is a disturbance in control of each other. As described above, the supercharging pressure and the EGR gas amount influence each other, and changing the EGR gas amount makes it necessary to change the nozzle opening. Since the control accuracy is reduced, the engine controller 31 calculates the target intake air amount tQac according to the operating conditions, and is a value obtained by performing a delay process on the target intake air amount tQac, the target EGR gas amount, and the target EGR rate Megr. A target opening ratio Rvnt of the variable nozzle 21d, which is an operation target value of the turbocharger 21, is set from a certain actual EGR gas amount Qec and an actual EGR rate Megrd.

  Here, the opening ratio of the variable nozzle 21d is the ratio of the current nozzle opening area to the nozzle opening area when the variable nozzle 21d is fully opened. Therefore, the opening ratio is 100% when the variable nozzle 21d is fully opened, and the opening ratio is 0% when the variable nozzle 21d is fully closed.

  FIG. 3A shows the target intake air amount tQac, the intake air amount Qac (actual intake air amount) in the current control, the target opening ratio Rvnt of the variable nozzle 21d, and the variable nozzle 21d during acceleration, for example, when fully opened from the idle state. The model shows how the actual aperture ratio changes. When the accelerator pedal is depressed for acceleration, the target intake air amount tQac increases stepwise as shown by the upper broken line in FIG. 3A. In response to the change in the target intake air amount tQac, the target opening ratio Rvnt in the current control increases stepwise as shown by the lower broken line in FIG. 3A (the variable nozzle 21d is stepped from the fully closed state to the fully open state). be opened). However, as shown by the thick solid line in the upper part of FIG. 3A, the response of the intake air amount Qac in the current control is slow and finally rises far behind the change in the target intake air amount tQac in the current control. There is a phenomenon that the target intake air amount tQac is exceeded. Since the intake air amount and the supercharging pressure are substantially equivalent values, when viewed as the supercharging pressure, the actual supercharging pressure rPb exceeds the target supercharging pressure tPb as shown by the upper solid line in FIG. 3B. In other words, so-called supercharging pressure overshoot occurs. In the current control, the target opening ratio Rvnt of the variable nozzle 21d is set according to the steady target intake air amount tQac, but during the acceleration operation, the actual intake air amount with respect to the target intake air amount tQac is set. Since Qac is accompanied by a delay, the target opening ratio Rvnt of the variable nozzle 21d is set to the opening side although supercharging is not applied. Then, since the supercharging pressure does not increase easily, feedback control works strongly in the second half of acceleration, leading to overshoot. The delay of the actual intake air amount Qac with respect to the target intake air amount tQac is until it appears as an increase in turbine work → an increase in compressor work → an increase in actual supercharging pressure → an increase in intake air amount Qac. 3B corresponds to FIG. 3A and shows how the target supercharging pressure tPb, the actual supercharging pressure rPb, the target opening ratio Rvnt of the variable nozzle 21d, and the actual opening ratio of the variable nozzle 21d in the current control are related. The model shows how it changes.

As a countermeasure at the time of this acceleration, the engine rotational speed Ne and calculates the product Pse of the target fuel injection amount Qsol, the values and the difference DPSE (= Pse-Pse the Pse _n-1 is the value of the previous product _{n- 1} ) is calculated, and a predetermined table is searched from the difference dPse to calculate an aperture ratio correction coefficient kRvnt, and a value obtained by multiplying the correction coefficient kRvnt by the target aperture ratio basic value is calculated as a target aperture ratio Rvnt. There are conventional devices. This is to cope with the fact that the boost pressure rises after the increase of the exhaust pressure during acceleration (the charging efficiency is lowered by the delay of the rise of the boost pressure). In other words, at the time of acceleration with a large load change, the exhaust pressure rises faster than the boost pressure rises, and the charging efficiency is likely to decrease by the difference between the exhaust pressure and the supercharging pressure. By increasing the correction coefficient kRvnt and increasing the opening ratio as it increases, a decrease in charging efficiency due to a delay in rising of the supercharging pressure during acceleration is avoided.

  However, the difference dPse becomes a sharp movement at a moment in the initial acceleration and in a minute time, and even if considering the acceleration response of the turbocharger 21, the movement of the turbocharger 21 cannot follow the correction value. It is thought that the controllability of is worsened. Moreover, the opening side correction of the opening ratio is limited to the initial stage of acceleration, and the countermeasure is only a delay in the rise of the boost pressure, and it does not correspond to the overshoot of the boost pressure.

  Therefore, the present invention, as shown by the one-dot chain line in the upper part of FIG. 3A, rises slowly in the early stage of acceleration, and has a characteristic intermediate between the target intake air amount tQac in the current control and the intake air amount Qac in the current control. The target intake air amount, which has a characteristic of suddenly rising, is newly introduced separately from the target intake air amount tQac in the current control. The newly introduced target intake air amount is defined as “supercharger control target intake air amount” in order to distinguish it from the target intake air amount tQac in the current control. When the target opening ratio Rvnt (operation target value of the variable capacity supercharger) of the variable nozzle 21d is set using the newly introduced supercharger control target intake air amount ctQac, the target opening ratio Rvnt in the present invention is: As shown by the dashed line in the lower part of FIG. 3A, the variable nozzle 21d remains relatively small without changing much in the initial stage of acceleration, that is, the variable nozzle 21d remains on the closed side, and becomes relatively large in the late stage of acceleration, that is, the variable nozzle 21d. Has a characteristic of suddenly opening. Further, since the target intake air amount tQac in the current control is a map value, an optimum target intake air amount is given in the steady state, but when the acceleration state is reached, the optimum target intake air amount can no longer be given. It is possible. Therefore, a target intake air amount during acceleration, that is, a supercharger control target intake air amount ctQac, is newly introduced as a value for reducing and correcting the target intake air amount during normal operation.

  When the supercharger control target intake air amount ctQac as the control target value at the time of acceleration of the variable capacity supercharger is set as described above, the intake air amount Qac (actual intake air amount) of the present invention is As indicated by the thin solid line in the upper part of 3A, unlike the intake air amount Qac in the current control, it responds to the supercharger control target intake air amount ctQac that is the target intake air amount at the time of acceleration without much response delay. It can be seen that overshooting of the supercharging pressure is avoided. In other words, even if the turbocharger 21 has a large response delay during acceleration, it is possible to give the control target value to the variable nozzle 21d for the first time so that the overshoot of the supercharging pressure does not occur in the first place. It became.

  FIG. 4 is a block diagram of this supercharging pressure control performed by the engine controller 31. In FIG. 4, blocks 42 to 54 representing the respective functions are provided for each input of a REF signal (crank angle reference position signal, a signal every 180 degrees for a 4-cylinder engine and a signal every 120 degrees for a 6-cylinder engine). The functions possessed by will be executed all at once.

In the present embodiment, the supercharging pressure control and the EGR control are cooperatively controlled, so the EGR control will be briefly described first. A basic target EGR rate Megarb [anonymous number] is calculated according to the engine speed Ne and the target fuel injection amount Qsol, and a water temperature correction is performed on the basic target EGR rate Megrb to obtain a target EGR rate Megr [anonymous number]. Looking for. The basic target EGR rate Megrb increases on the side where the engine is frequently used, that is, on the low rotation speed side and the low load side, and decreases on the high output side where smoke is likely to occur. Using such a basic target EGR rate Megrb and the intake air amount Qacn [mg / st] (described later) per cylinder at the collector portion 11a position,
Mqec = Qacn × Megrb (1)
The required EGR gas amount Mqec [mg / st] is calculated by the following equation. This required EGR gas amount Mqec represents the required amount of EGR gas per cylinder determined according to the operating state. Then, for this required EGR gas amount Mqec, KIN × KVOL is set as a weighted average coefficient.
Rqec = Mqec × KIN × KVOL + Rqec _n−1 × (1−KIN × KVOL)
... (2)
Where KIN: volumetric efficiency equivalent value,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
Rqec _n-1 : last intermediate processing value,
The intermediate processing value (weighted average value) Rqec [mg / st] is calculated by the following equation (first-order lag equation), and using this Rqec and the required EGR gas amount Mqec,
Tqec = Mqec × GKQEC + Rqec _n−1 × (1-GKQEC)
... (3)
However, GKQEC: Lead correction gain,
The target EGR gas amount Tqec [mg / st] per cylinder is calculated by performing advance correction using the following equation. In the above equations (2) and (3), there is a delay in the intake system with respect to the required value (that is, a delay in the capacity of the EGR valve 14 → the collector 11a → the intake manifold → the intake valve 8). Is performed.

And for the target EGR gas amount Tqec per cylinder,
Tqek = Tqec × (Ne / KCON #) (4)
Where KCON # is a constant,
The unit conversion (per cylinder → per unit time) is performed by the following formula to calculate the target EGR gas amount Tqek [g / sec], and from the target EGR gas amount Tqek and the EGR gas flow velocity Cqe,
Aev = Tqek / Cqe (5)
The EGR valve opening area Aev is calculated by the following formula. The EGR valve opening area Aev is converted into a lift amount of the EGR valve 14, and a control signal is generated and output to the step motor so as to be the EGR valve lift amount.

  This completes the overview of EGR control.

  Returning to FIG. 4, in the present invention, a supercharger control target intake air amount calculation unit 41 is newly provided to calculate the supercharger control target intake air amount ctQac. The supercharger control target intake air amount calculation unit 41 includes a subtracter 42, a subtractor 43, a calculation unit 44, a minimum value selection unit 45, and an adder 46.

  First, the subtractor 42 subtracts the intake air amount Qac [mg / st] from the target intake air amount Qac [mg / st] to calculate the intake air amount deviation dQac [mg / st].

Here, the intake air amount Qac, which is a detected value of the air amount actually taken into the cylinder, is obtained as follows. That is, from the engine rotation speed Ne and the intake air amount Qas0 [g / sec] obtained by the air flow meter 36,
Qac0 = Qas0 / Ne × KCONT # (6)
Where KCONT # is a constant,
The intake air amount Qac0 [mg / st] per cylinder is calculated by the following equation. The air flow meter 36 is provided upstream of the intake compressor 21a, and in order to perform delay processing corresponding to the transport delay from the air flow meter 36 position to the collector portion 11a, the value of Qac0 before L (L is a constant) times is used as the collector portion 11a position. Is obtained as an intake air amount Qacn [mg / st] per cylinder. And with respect to this intake air amount Qacn,
Qac = Qac _n-1 × (1-KIN × KVOL) + Qacn × KIN × KVOL
... (7)
Where KIN: volumetric efficiency equivalent value,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
Qac _n-1 : Previous Qac,
The intake air amount Qac [mg / st] per cylinder at the intake valve 8 position is calculated by the following equation (primary delay equation). This is to compensate for the dynamics from the collector portion 11a to the intake valve 8. Thus, the intake air amount Qac in this embodiment calculates (detects) the amount of air actually flowing into the cylinder (combustion chamber 9).

  Next, the target intake air amount tQac, that is, the target intake air amount tQac as a target value of the cylinder inflow air amount, is calculated from, for example, the engine speed Ne [rpm] and the target fuel injection amount Qsol [mg / st]. What is necessary is just to obtain | require by searching the map which contains FIG. As described in Japanese Patent Application Laid-Open No. 2001-123873, in the EGR region, the target intake air amount basic value tQacb is calculated by searching a predetermined map from the engine speed Ne and the actual EGR rate Megard. The target intake air amount correction coefficient ktQac is calculated by searching a predetermined map from the engine speed Ne and the target fuel injection amount Qsol, and a value obtained by multiplying the correction intake coefficient ktQac by the target intake air amount basic value tQacb is calculated. The target intake air amount Qac may be used. Since the target intake air amount tQac here is a map value (adapted value), it basically represents the target intake air amount in a steady state. Therefore, even if the optimum target intake air amount is given in the steady state, the optimum target intake air amount can no longer be given in the acceleration state.

  The subtractor 43 calculates the supercharging pressure deviation dPb [kPa] (= tPb−rPb) by subtracting the actual supercharging pressure rPb [kPa] from the target supercharging pressure tPb [kPa]. Here, the target boost pressure tPb may be obtained, for example, by searching a map having the contents shown in FIG. 6 from the engine speed Ne and the target fuel injection amount Qsol. The actual supercharging pressure rPb is detected by a supercharging pressure sensor 37 provided in the intake passage 11 downstream of the intercooler 22.

  The target intake air amount deviation calculation unit 44 searches the map having the contents shown in FIG. 7 from the boost pressure deviation dPb and the actual exhaust flow rate rQexh [g / sec], thereby obtaining the target intake air amount deviation tdQac [mg / st]. The minimum part selecting unit 45 selects and outputs the smaller one of the target intake air amount deviation tdQac and the intake air amount deviation dQac. The adder 46 calculates a value obtained by adding the value output from the selection unit 45 to the intake air amount Qac as a supercharger control target intake air amount ctQac [mg / st].

  Here, the target intake air amount deviation tdQac as a variable value is a smaller value as a whole than the intake air amount deviation dQac calculated during acceleration. Therefore, the target intake air amount deviation tdQac is output from the minimum value selection unit 45 instead of the intake air amount deviation dQac during acceleration.

  However, since the target intake air amount deviation tdQac is configured as a variable value, the tendency of the value is as follows. That is, as shown in FIG. 7, the target intake air amount deviation tdQac becomes relatively small as the boost pressure deviation dPb becomes relatively large under the condition that the actual exhaust flow rate rQexh is constant. The target intake air amount deviation tdQac is relatively increased as the actual exhaust flow rate rQexh is relatively increased under a constant supply pressure deviation dPb. For this reason, the target intake air amount deviation tdQac changes as follows when considering the entire period from the initial acceleration to the late acceleration. In other words, the boost pressure deviation dPb is relatively large and the actual exhaust flow rate rQexh is relatively small at the beginning of acceleration, and the boost pressure deviation dPb is relatively small and the actual exhaust flow rate rQexh is relatively small. It becomes a relatively large value in the latter half of acceleration when it becomes relatively large. In addition, the value changes smoothly from the initial value of acceleration to the initial value of acceleration between the initial stage of acceleration and the late stage of acceleration. In other words, the turbocharger control has such a characteristic that the change waveform of the turbocharger control target intake air amount ctQac shown in the upper one-dot chain line in FIG. 3A is obtained, that is, a characteristic that rises slowly in the early stage of acceleration and rises rapidly in the late stage of acceleration. The map value of the target intake air amount deviation tdQac shown in FIG. 7 is set by adaptation so that the target intake air amount ctQac is obtained.

  More specifically, since it is desired to obtain a turbocharger control target intake air amount ctQac having a characteristic of slowly rising in the early stage of acceleration and rapidly rising in the late stage of acceleration, the supercharging pressure deviation dPb is relatively large and the actual exhaust gas flow rate. At the beginning of acceleration when rQexh is relatively small, a positive value close to zero is set as the target intake air amount deviation tdQac, and at the later stage of acceleration where the supercharging pressure deviation dPb is relatively small and the actual exhaust flow rate rQexh is relatively large. Sets a value close to the intake air amount deviation dQac in the current control within a range not exceeding the intake air amount deviation dQac in the current control. A value that smoothly connects a value close to the air amount deviation dQac is set. Eventually set by conformance.

In FIG. 4, the remaining part other than the supercharger control target intake air amount calculation unit 41 is the same as the current control. That is, the multiplier 47 multiplies the target fuel injection amount Qsol by the gain QFGAN #, and the adder 48, the multiplier 49, and the divider 50
tQas0 = (ctQac + Qsol × QFGAN #) × Ne / KCON #
... (8)
Where KCON # is a constant,
The calculated exhaust flow rate tQas0 [g / sec] is calculated by the following formula.

  In equation (8), Qsol × QFGAN # is added to the turbocharger control target intake air amount ctQac so that load correction can be made to the calculated exhaust flow rate and its sensitivity is adjusted by gain QFGAN #. It is what you do. Ne / KCON # is a value for converting the intake air amount per unit time.

  The target opening ratio setting unit 51 searches the map having the contents shown in FIG. 8 from the calculated exhaust gas flow rate tQas0 and the calculated EGR gas amount tQes0 [g / sec] thus obtained, thereby setting the target of the variable nozzle 21d. An opening ratio Rvnt [%] is calculated. As shown in FIG. 8, the target opening ratio Rvnt slightly increases on the low load side when the calculated EGR gas amount tQes0 is constant, and once the load (that is, the calculated exhaust flow rate tQas0) becomes larger than this, It is a value that becomes larger according to the load after becoming smaller. When the calculated exhaust flow rate tQas0 is constant, the target opening ratio Rvnt decreases as the calculated EGR gas amount tQes0 increases.

The calculated EGR gas amount tQes0 is calculated using the cylinder intake EGR gas amount Qec [mg / st]
tQes0 = (Qec + Qsol × QFGAN #) × Ne / KCON #
... (9)
Where KCON # is a constant,
It is calculated by the following formula.

The calculation method of the cylinder intake EGR gas amount Qec in the first term on the right side of the equation (9) is the same as the intake air amount Qac. That is, from the intake air amount Qacn per cylinder at the collector portion 11a position (used for calculating Qac) and the target EGR rate Megr [anonymous number], the EGR gas amount Qec0 per cylinder at the collector portion 11a position is calculated. mg / st]
Qec0 = Qacn × Megr (10)
And using the EGR amount Qec0 per cylinder at the collector portion 11a position,
Qec = Qec0 × Kkin × Ne × KE #
+ Qec _n-1 × (1-Kkin × Ne × KE #) (11)
However, Kkin: kin × KVOL,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
KE #: constant,
Qec _n-1 : Previous Qec,
The cylinder intake EGR gas amount Qec [mg / st] is calculated by performing the delay process and the unit conversion (per cylinder → per unit time) at the same time as the above equation (7), using the above equation (primary delay equation). To do. The actual EGR rate Megrd is also the same as the equation (11), that is, using the target EGR rate Megr.
Megrd = Megr × Kkin × Ne × KE2 #
+ Megrd _n-1 × (1-Kkin × Ne × KE2 #)
(12)
However, Kkin: kin × KVOL,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
KE2 #: constant,
Megrd _n-1 : last Megrd,
It is calculated by the formula (first-order lag formula).

  In this embodiment, the target opening ratio Rvnt is calculated from the calculated exhaust flow rate tQas0 and the calculated EGR gas amount tQes0. Instead of the calculated exhaust flow rate tQas0, the supercharger control target intake of the first term on the right side of the equation (8) is calculated. In place of the calculated EGR gas amount tQes0, the cylinder intake EGR gas amount Qec in the first term on the right side of the equation (9) can be used as the air amount ctQac (see FIG. 8).

Further, the adder 52, the multiplier 53, and the divider 54 use the intake air amount Qac [mg / st],
rQexh = (Qac + Qsol × QFGAN #) × Ne / KCON #
... (13)
Where KCON # is a constant,
The actual exhaust flow rate rQexh [g / sec] is calculated by the following equation. Expression (13) is the same expression as Expressions (8) and (9) above. The actual exhaust flow rate rQexh obtained in this way is used by the target intake air amount deviation calculation unit 44.

  Here, the effect of this embodiment is demonstrated.

  According to the present embodiment (the embodiment of the invention described in claim 1), the turbocharger 21 having the variable nozzle 21d and the EGR valve 14 (EGR device) are provided, and the target EGR gas amount Tqec (EGR device) is provided. Control target value) is calculated according to the operating conditions, the EGR valve 14 is controlled so as to be the target EGR gas amount Tqec, the target supercharging pressure tPb is calculated according to the operating conditions, and the actual supercharging pressure rPb And a turbocharger as a value for reducing and correcting the target intake air amount tQac (control target value at the steady state of the variable capacity turbocharger) based on the target boost pressure tPb and the actual boost pressure rPb A control target intake air amount ctQac (control target value during acceleration of the variable capacity supercharger) is calculated, and this supercharger control target intake air amount ctQac and cylinder intake EGR gas amount Qec (actual control value of the EGR device) Based on Therefore, the target opening ratio Rvnt (operation target value of the variable capacity supercharger) of the variable nozzle 21d is set, and the variable nozzle 21d of the turbocharger 21 is controlled so as to be the target opening ratio Rvnt. The control target intake air amount ctQac gives the optimum target intake air amount at the time of acceleration, and the supercharging pressure control can be realized so that the overshoot of the supercharging pressure does not occur at the time of acceleration.

  This embodiment corresponds to the fact that the supercharging pressure deviation dPb is relatively large in the early stage of acceleration and the supercharging pressure deviation dPb is relatively small in the late stage of acceleration. (Embodiment of the Invention of Claim 2) According to the above, the supercharger control target intake air amount ctQac (control target value during acceleration of the variable capacity supercharger) is determined based on the target supercharging pressure tPb and the supercharging pressure deviation dPb of the actual supercharging pressure rPb. Since the calculation is performed, it is possible to provide the supercharger control target intake air amount ctQac that well corresponds to such a change in the supercharging pressure deviation dPb.

  The present embodiment (implementation of the invention according to claim 3) corresponds to the fact that the turbo work is different between the initial stage of acceleration where the actual exhaust flow rate rQexh is relatively small and the late stage of acceleration where the actual exhaust flow rate rQexh is relatively large. According to the embodiment, the supercharger control target intake air amount ctQac (control target value at the time of acceleration of the variable capacity supercharger) is also calculated based on the actual exhaust flow rate rQexh. The supercharger control target intake air amount ctQac that corresponds well to the change in the actual exhaust flow rate rQexh in the entire acceleration can be provided.

  According to the present embodiment (the embodiment of the invention described in claim 4), the steady-state target intake air amount calculation for calculating the steady-state target intake air amount tQac as the steady-state control target value of the turbocharger 21. And the control target value at the time of acceleration of the variable capacity supercharger is a supercharger control target intake air amount ctQac having a value smaller than a target intake air amount tQac (representing a target intake air amount in a steady state). Therefore, the turbocharger control target intake air amount ctQac having a characteristic of slowly rising at the early stage of acceleration and rapidly rising at the late stage of acceleration can be provided.

  The flowcharts of FIGS. 9 and 12 are for calculating the target opening ratio Rvnt of the second and third embodiments. Each flow is executed every time the REF signal is input. In FIG. 12, the same steps as those in FIG.

  In the first embodiment, the target intake air amount deviation tdQac is calculated based on the boost pressure deviation dPb and the actual exhaust flow rate rQexh, and the calculated target intake air amount difference tdQac is added to the intake air amount Qac. Although the turbocharger control target intake air amount ctQac is calculated, the second embodiment directly calculates the supercharger control target intake air amount ctQac based on the supercharging pressure deviation dPb and the actual exhaust flow rate rQexh. . The third embodiment is a variation of the second embodiment.

  First, from the second embodiment, in step 1 in FIG. 9, the target boost pressure tPb, the actual boost pressure rPb, the actual exhaust flow rate rQexh, and the target EGR rate Megr are read. These values are all obtained in the first embodiment.

  In step 2, a supercharging pressure deviation dPb is calculated by subtracting the actual supercharging pressure rPb from the target supercharging pressure tPb, and a map having the contents shown in FIG. 10 is retrieved from the supercharging pressure deviation dPb and the actual exhaust flow rate rQexh. Thus, the supercharger control target intake air amount ctQac is calculated. As shown in FIG. 10, the supercharger control target intake air amount ctQac becomes relatively smaller as the supercharging pressure deviation dPb is relatively larger under the condition that the actual exhaust flow rate rQexh is constant, and the supercharging pressure deviation dPb is increased. Is a value that becomes relatively larger as the actual exhaust flow rate rQexh becomes relatively larger under certain conditions.

  In this case, the minimum value of the supercharger control target intake air amount ctQac is made to coincide with the intake air amount Qac or set to a value close to the intake air amount Qac within a range not lower than the intake air amount Qac. The maximum value of the supercharger control target intake air amount ctQac is made to coincide with the target intake air amount tQac or close to the target intake air amount tQac within a range not exceeding the target intake air amount tQac. The reason why the turbocharger control target intake air amount ctQac is relatively small in the initial stage of acceleration when the actual exhaust flow rate rQexh is relatively small and the supercharging pressure deviation dPb is relatively large is shown by the upper constant chain line in FIG. 3A. This is because the turbocharger control target intake air amount ctQac is slowly raised at the early stage of acceleration. On the other hand, the reason why the turbocharger control target intake air amount ctQac is relatively increased in the latter half of the acceleration in which the actual exhaust flow rate rQexh is relatively large and the supercharging pressure deviation dPb is relatively small is the upper part of FIG. 3A. This is because the turbocharger control target intake air amount ctQac is suddenly raised in the latter half of acceleration as indicated by the chain line.

  In step 4, the target opening ratio Rvnt is set by searching a map having the contents shown in FIG. 11 from the supercharger control target intake air amount ctQac and the target EGR rate Megr thus obtained.

  As described above, according to the second embodiment (the embodiment of the invention described in claim 5), supercharging is performed at the initial stage of acceleration in which the supercharging pressure deviation dPb is relatively large and the actual exhaust flow rate rQexh is relatively small. Since the machine control target intake air amount ctQac is set to the intake air amount Qac or close to the intake air amount Qac within a range not lower than the intake air amount Qac, the turbocharger control target intake air amount ctQac that rises slowly in the early stage of acceleration Can be given.

  Further, according to the second embodiment (the embodiment of the invention described in claim 6), the supercharger control is performed in the later stage of acceleration in which the supercharging pressure deviation dPb is relatively small and the actual exhaust flow rate rQexh is relatively large. Since the target intake air amount ctQac is set to the target intake air amount tQac or close to the target intake air amount tQac within a range not exceeding the target intake air amount tQac, the turbocharger control target intake air that suddenly rises in the latter half of the acceleration The quantity ctQac can be given.

  Next, it moves to 3rd Embodiment. In the third embodiment, parts different from the second embodiment will be mainly described. In FIG. 12, in step 11, in addition to the target boost pressure tPb, the actual boost pressure rPb, the actual exhaust flow rate rQexh, and the target EGR rate Megr, the intake air amount Qac and the target intake air amount tQac are read. The values of the intake air amount Qac and the target intake air amount tQac are also obtained in the first embodiment.

In step 12, a gain ktQac is calculated by searching a map having the contents shown in FIG. 13 from the boost pressure deviation dPb and the actual exhaust gas flow rate rQexh. In step 13, the gain ktQac is used,
ctQac = (Qac−tQac) × ktQac + tQac (14)
The supercharger control target intake air amount ctQac is calculated by the following formula.

  As shown in FIG. 13, the gain ktQac is a variable value from 0 to 1, and approaches 1 as the boost pressure deviation dPb is relatively large under the condition that the actual exhaust flow rate rQexh is constant, and the boost pressure deviation dPb. Becomes closer to zero as the actual exhaust flow rate rQexh becomes relatively large under a constant condition. The gain ktQac is 1 at the beginning of acceleration when the actual exhaust flow rate rQexh is relatively small and the boost pressure deviation dPb is relatively large. At this time, the supercharger control target intake air amount ctQac is equal to the intake air amount Qac from the equation (14). As described above, the reason why the gain ktQac is set to 1 in the early stage of acceleration is to allow the turbocharger control target intake air amount ctQac to rise slowly in the early stage of acceleration as shown by the upper fixed chain line in FIG. 3A. On the other hand, the gain ktQac becomes zero at the late stage of acceleration when the actual exhaust flow rate rQexh is relatively large and the boost pressure deviation dPb is relatively small. At this time, the supercharger control target intake air amount ctQac is equal to the target intake air amount tQac from the equation (14). Thus, the reason why the gain ktQac is set to zero in the latter half of the acceleration is to make the supercharger control target intake air amount ctQac suddenly rise in the latter half of the acceleration as shown by the upper fixed chain line in FIG. 3A.

  In step 4, the target opening ratio Rvnt is set by searching a map having the contents shown in FIG. 11 from the supercharger control target intake air amount ctQac and the target EGR rate Megr thus obtained.

  Thus, according to the third embodiment (the embodiment of the invention described in claim 8), the supercharger control target intake air amount ctQac is set to the difference between the intake air amount Qac and the target intake air amount tQac (= Qac−tQac) is calculated by adding the target intake air amount tQac to the value obtained by multiplying the gain ktQac, which is a value from zero to 1, so that, as in the second embodiment, it rises slowly in the early stage of acceleration and in the late stage of acceleration. The supercharger control target intake air amount ctQac having a characteristic of rapidly rising can be provided.

  The boost pressure deviation dPb is relatively large and the actual exhaust flow rate is relatively small in the early stage of acceleration, and the boost pressure deviation dPb is relatively small and the actual exhaust flow rate is relatively large in the late stage of acceleration. Correspondingly, according to the third embodiment (the embodiment of the invention described in claim 9), since the gain ktQac is a value corresponding to the supercharging pressure deviation dPb and the actual exhaust flow rate rQexh, the supercharging pressure deviation dPb In addition, the supercharger control target intake air amount ctQac can be provided that corresponds well to the change in the actual exhaust flow rate rQexh.

  In the embodiment, the case where the “supercharging pressure” is used (the target supercharging pressure tPb is calculated according to the operation condition and the actual supercharging pressure is detected by the sensor) has been described, but the back pressure is used. It is desirable to calculate the target back pressure according to the operating conditions and detect the actual back pressure with a sensor. Here, “back pressure” refers to the exhaust pressure upstream of the exhaust turbine 21b. This is because the back pressure directly acting on the exhaust turbine 21b is more directly related to turbine work than the “supercharging pressure” that is the pressure downstream of the intake compressor 21a. The characteristic of the target back pressure is considered to be the same characteristic as the characteristic of the target boost pressure tPb shown in FIG.

  In the embodiment, the variable capacity supercharger is the turbocharger 21 having the variable nozzle. However, the turbocharger in which the variable capacity supercharger is provided with a waste gate valve in a passage that bypasses the exhaust turbine. This also applies to the case of a feeder. In a turbocharger having a variable nozzle, the opening degree of the variable nozzle is controlled. In a turbocharger provided with a wastegate valve, the opening degree of the wastegate valve may be controlled.

  In the embodiment, the description has been given of the case of the diesel engine including the turbocharger having the variable nozzle and the EGR device. However, the present invention can be applied to the case of the gasoline engine including the turbocharger having the variable nozzle and the EGR device. There is application.

  In the embodiment, the operation target value of the variable capacity supercharger is described as the target opening ratio Rvnt of the variable nozzle. However, the operation target value of the variable capacity supercharger is a value equivalent to the opening area of the variable nozzle. It does not matter.

  In the embodiment, the case where the control target value of the EGR device is the target EGR gas amount Tqec has been described. However, the control target value of the EGR device may be the target EGR rate Megr.

  In the embodiment, the case where the actual control value of the EGR device is the cylinder intake EGR gas amount Qec has been described. However, the actual control value of the EGR device may be the actual EGR rate Megrd.

1 Engine body 6 Fuel injection valve 14 EGR valve (EGR device)
21 Turbocharger (variable capacity turbocharger)
31 Engine controller 37 Boost pressure sensor

Claims (13)

It has a variable capacity supercharger and an EGR device,
EGR device control target value calculating means for calculating a control target value of the EGR device according to operating conditions;
EGR device control means for controlling the EGR device so as to be a control target value of the EGR device;
Target value calculating means for calculating the target back pressure or the target supercharging pressure according to the operating conditions;
Actual value detecting means for detecting actual back pressure or actual supercharging pressure;
Based on these target back pressure and actual back pressure, or on the basis of the target supercharging pressure and actual supercharging pressure, the variable capacity as a value for reducing and correcting the control target value in the steady state of the variable capacity supercharger. Acceleration control target value calculation means for calculating a control target value at the time of acceleration of the turbocharger;
The operation target value for setting the operation target value of the variable capacity supercharger based on the control target value at the time of acceleration of the variable capacity supercharger and the control target value of the EGR apparatus or the actual control value of the EGR apparatus Setting means;
An engine control device comprising: a supercharger control means for controlling the variable capacity supercharger so as to be an operation target value of the variable capacity supercharger.   2. The engine control according to claim 1, wherein a control target value at the time of acceleration of the variable capacity supercharger is calculated based on a supercharging pressure deviation between the target supercharging pressure and an actual supercharging pressure. apparatus.   The engine control device according to claim 2, wherein the control target value at the time of acceleration of the variable capacity supercharger is also calculated based on an actual exhaust flow rate. A steady-state target intake air amount calculating means for calculating a steady-state target intake air amount as a steady-state control target value of the variable capacity supercharger;
The engine control target value at the time of acceleration of the variable capacity supercharger is a supercharger control target intake air amount having a value smaller than the steady target intake air amount. Control device. Provided with an actual intake air amount detection means for detecting the actual intake air amount;
In the initial stage of acceleration when the supercharging pressure deviation is relatively large and the actual exhaust flow rate is relatively small, the supercharger control target intake air amount is set as the actual intake air amount or less than the actual intake air amount. 5. The engine control device according to claim 4, wherein the value is close to the actual intake air amount in a range that does not exist.   In the later stage of acceleration in which the supercharging pressure deviation is relatively small and the actual exhaust flow rate is relatively large, the supercharger control target intake air amount is set as the steady-state target intake air amount or 5. The engine control device according to claim 4, wherein the engine intake device has a value close to a target intake air amount in a steady state within a range not exceeding the target intake air amount. Provided with an actual intake air amount detection means for detecting the actual intake air amount;
In the initial stage of acceleration when the supercharging pressure deviation is relatively large and the actual exhaust flow rate is relatively small, the supercharger control target intake air amount is set as the actual intake air amount or less than the actual intake air amount. Set the value close to the actual intake air amount within the
In the later stage of acceleration in which the supercharging pressure deviation is relatively small and the actual exhaust flow rate is relatively large, the supercharger control target intake air amount is set as the steady-state target intake air amount or The target intake air amount is set to a value close to the target intake air amount in the steady state within the range not exceeding the target intake air amount, and the turbocharger control target intake air amount in the initial acceleration and late acceleration is the value in the early acceleration and the late acceleration. The engine control device according to claim 4, wherein the values are smoothly connected to each other. Provided with an actual intake air amount detection means for detecting the actual intake air amount;
The steady-state target intake air is obtained by multiplying the supercharger control target intake air amount by a value obtained by multiplying the difference between the actual intake air amount and the steady-state target intake air amount by a gain that is a value from zero to 1. The engine control apparatus according to claim 4, wherein the calculation is performed by adding the amounts.   The engine control device according to claim 8, wherein the gain is a value corresponding to the supercharging pressure deviation and the actual exhaust flow rate.   5. The target intake air amount at the normal time is calculated based on the engine speed and the EGR rate in the EGR region according to the engine speed and the load except in the EGR region. The engine control device described.   2. The engine control device according to claim 1, wherein the operation target value of the variable capacity supercharger is a variable nozzle opening area equivalent value or a variable nozzle target opening ratio.   The engine control device according to claim 1, wherein the control target value of the EGR device is a target EGR gas amount or a target EGR rate.   The engine control device according to claim 1, wherein the actual control value of the EGR device is a cylinder intake EGR gas amount or an actual EGR rate.

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