JP3603685B2 - Control unit for diesel engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a diesel engine, particularly to a control device including an EGR device (a device for recirculating a part of exhaust gas to an intake passage) and a common rail type fuel injection device.
[0002]
[Prior art]
If a large amount of EGR is performed, smoke is generated. Therefore, a target EGR rate (or EGR amount) is determined according to the engine operating conditions (engine speed, engine load) so that smoke is not generated. In the case of rapid acceleration, the fuel injection amount is increased without time delay, whereas the mechanical delay of the EGR device delays the reduction of the EGR rate (EGR amount), so that the EGR rate (EGR amount) is excessive. And smoke is generated due to poor combustion.
[0003]
Therefore, a sudden acceleration is detected from the operating conditions and the common rail pressure is corrected to the high pressure side for a certain period, or the actual EGR rate is detected by the EGR rate detecting means. There has been proposed an arrangement in which the common rail pressure is corrected to a higher pressure side at the time of higher acceleration (for the former, see JP-A-6-299895 and for the latter, see JP-A-9-242617).
[0004]
As will be described later, the common rail fuel injection device mainly includes a fuel tank, a supply pump, a common rail (accumulation chamber), and a fuel injection nozzle provided for each cylinder. The high-pressure fuel generated by the high-pressure supply pump is supplied to the common rail. The start and end of the injection can be freely controlled by opening and closing the nozzle needle by a three-way valve in the fuel injection nozzle. The common rail pressure is the fuel pressure stored in the common rail.
[0005]
[Problems to be solved by the invention]
By the way, the reason why the common rail pressure (fuel injection pressure) is temporarily increased when the EGR rate (EGR amount) at the time of rapid acceleration is excessively small is that fuel spray is miniaturized and spray reach distance is increased. The aim is to increase the amount of air taken in to reduce smoke, which is an incomplete combustion component.
[0006]
However, since the common rail pressure is originally high (for example, the maximum pressure is about 140 MPa), correcting the common rail pressure to a higher pressure side even when accelerating increases the drive loss of the supply pump, and the supply pump is driven by the engine. For this reason, fuel consumption is deteriorated due to the increase in drive loss.
[0007]
In addition, there is a possibility that the common rail pressure corrected to the high pressure side exceeds the allowable common rail pressure due to variations or control incompatibility. In this case, the durability of the common rail fuel injection device is reduced.
[0008]
Therefore, the present invention corrects the EGR rate (EGR amount) instead of the common rail pressure in order to eliminate the deviation of the actual EGR rate from the target EGR rate during acceleration. It is an object of the present invention to prevent an increase in smoke and to prevent deterioration of fuel efficiency and a decrease in durability of a common rail fuel injection device due to an increase in drive loss of a supply pump even if a common rail fuel injection device is provided.
[0009]
[Means for Solving the Problems]
The first invention, as shown in FIG. 70, includes an EGR device 61, means 62 for calculating a control target value (for example, a target EGR rate and a target EGR amount) of the EGR device 61 in accordance with an engine load, Means 63 for calculating a target injection pressure according to the load of the fuel cell, means 64 for controlling the fuel injection pressure so as to attain the target injection pressure, means 65 for detecting the actual injection pressure, A means 66 for comparing the injection pressure, a means 67 for reducing the control target value when the actual injection pressure is lower than the target injection pressure (during acceleration) based on the result of the comparison, and a means for reducing the corrected control target value. And means 68 for controlling the EGR device 61.
[0010]
In a second aspect, in the first aspect, the target injection pressure is an injection pressure for a request in a steady state.
[0011]
In a third aspect, in the first aspect, the control target value is a target EGR rate or a target EGR amount.
[0012]
According to a fourth aspect, in the first aspect, the fuel injection system further includes a common rail type fuel injection device, wherein the fuel injection pressure is a common rail pressure.
[0013]
In a fifth aspect, in the first aspect, the rate at which the control target value is reduced and corrected is changed according to the engine load.
[0014]
As shown in FIG. 71, the sixth invention includes an EGR device 61 and a supercharger 71, and controls a control target value (for example, a target EGR rate or a target EGR amount) of the EGR device 61 according to an engine load. A calculating means 62; a means 72 for calculating a target intake air amount tQac or a target supercharging pressure according to the operating conditions; and a control target value of the EGR device 61 based on the target intake air amount tQac or the target supercharging pressure. Means 73 for setting an operation target value of the supercharger 71 based on the above, means 74 for controlling the supercharger 71 so as to be the operation target value of the supercharger 71, and a target corresponding to the load of the engine. Means 63 for calculating the injection pressure, means 64 for controlling the fuel injection pressure to achieve this target injection pressure, means 65 for detecting the actual injection pressure, and means for comparing this actual injection pressure with the target injection pressure 66 and this comparison When the actual injection pressure is lower than the target injection pressure (during acceleration), the control target value is reduced and corrected. When the actual injection pressure matches the target injection pressure (at a steady state), the control target value is reduced and corrected. Means 75 that does not perform the control so that, when the actual injection pressure is lower than the target injection pressure, the control target value is reduced and corrected when the actual injection pressure matches the target injection pressure. Means 76 is provided for controlling the EGR device 61 so that the control target value is not corrected.
[0015]
【The invention's effect】
During acceleration, the actual control value becomes larger than the control target value of the EGR device, and this shift causes smoke. On the other hand, according to the first, second, and third inventions, the actual injection pressure becomes lower than the target injection value. Since the control target value of the EGR device is corrected to decrease at the time of acceleration lower than the pressure, generation of smoke at the time of acceleration can be prevented.
[0016]
In this case, with the common rail type fuel injection device (the common rail pressure becomes the fuel injection pressure), it is possible to prevent the generation of smoke during acceleration by correcting the common rail pressure to the high pressure side for a certain period of time. If the high common rail pressure is corrected to the high pressure side, the drive loss of the supply pump is increased, and the fuel consumption is deteriorated due to the increase in the drive loss. However, according to the fourth invention, the common rail pressure is increased even during acceleration. Since there is no correction on the side, even if the common rail type fuel injection device is provided, it is possible to prevent deterioration of fuel efficiency due to an increase in drive loss of the supply pump and decrease in durability of the common rail type fuel injection device.
[0017]
According to the fifth aspect, it is possible to cope with the fact that the amount (sensitivity) to be corrected differs depending on the engine load even for the same injection pressure error. For example, the rate at which the control target value is decreased and corrected is changed according to the engine load corresponding to the load during acceleration, and the rate at which the control target value is decreased and corrected during acceleration with a large load is made larger than during acceleration with a small load ( That is, by making the control target value smaller during acceleration with a large load than during acceleration with a small load, it is possible to prevent the occurrence of smoke with good response even during acceleration with a large load.
[0018]
According to the sixth aspect, the target intake air amount (or the target supercharging pressure) is calculated according to the operating conditions, and the operation of the supercharger is performed based on the target intake air amount and the control target value of the EGR device. Since the target value is set, even if the control target value of the EGR device changes, the target intake air amount can be obtained, and the controllability of the supercharger and the EGR device including the transient is improved, Thereby, the performance of each other can be sufficiently exhibited. It is also possible to simplify adaptation and logic.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a configuration for performing so-called low-temperature premixed combustion in which the pattern of heat generation is single-stage combustion. This configuration itself is known from Japanese Patent Application Laid-Open No. 8-86251.
[0020]
Now, the generation of NOx greatly depends on the combustion temperature, and lowering the combustion temperature is effective in reducing it. In the low-temperature premixed combustion, in order to realize low-temperature combustion by reducing the oxygen concentration by EGR, the control negative pressure from the negative pressure control valve 5 is applied to the EGR passage 4 connecting the exhaust passage 2 and the collector 3 a of the intake passage 3. And a diaphragm type EGR valve 6 which responds to the pressure.
[0021]
The negative pressure control valve 5 is driven by a duty control signal from the control unit 41, and thereby obtains a predetermined EGR rate according to operating conditions. For example, the EGR rate is set to a maximum of 100% in a low-speed low-load region, and the EGR rate is reduced as the rotational speed and the 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 reducing NOx is reduced due to the rise of the intake air temperature, and the ignition delay period of the injected fuel is shortened, so that premixed combustion cannot be realized. For such reasons, the EGR rate is gradually reduced.
[0022]
In the middle of the EGR passage 4, an EGR gas cooling device 7 is provided. This is because the water jacket 8 is formed around the EGR passage 4 and circulates a part of the engine cooling water, and the flow rate control valve 9 provided at the cooling water inlet 7a and capable of adjusting the circulation amount of the cooling water. In other words, in accordance with a command from the control unit 41, the cooling degree of the EGR gas increases as the circulation amount increases via the control valve 9.
[0023]
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 control unit 41 closes the swirl control valve in a low rotation and low load range, the flow rate of intake air taken into the combustion chamber increases, and swirl is generated in the combustion chamber.
[0024]
The combustion chamber is a large diameter toroidal combustion chamber (not shown). In this, the piston cavity is formed in a cylindrical shape from the crown surface to the bottom of the piston without restricting the inlet. A conical portion is formed to further improve the mixing of the air and the fuel so as not to be mixed. The swirl generated by the above-described swirl valve or the like due to the cylindrical piston cavity that does not restrict the inlet is diffused from the inside of the piston cavity to the outside of the cavity as the piston descends in the combustion process, and even outside the cavity. Swirl is maintained.
[0025]
The engine includes a common rail type fuel injection device 10. The configuration of the common rail type fuel injection device 10 is also known (refer to the 13th Internal Combustion Engine Symposium Proceedings, pp. 73-77), and is outlined with reference to FIG.
[0026]
The fuel injection device 10 mainly includes a fuel tank 11, a fuel supply passage 12, a supply pump 14, a common rail (pressure accumulating chamber) 16, and a nozzle 17 provided for each cylinder. After being temporarily stored in the accumulator 16 via the supply passage 15, the high-pressure fuel in the common rail 16 is distributed to the nozzles 17 for the number of cylinders.
[0027]
The nozzle 17 includes a needle valve 18, a nozzle chamber 19, a fuel supply passage 20 to the nozzle chamber 19, a retainer 21, a hydraulic piston 22, a return spring 23 for urging the needle valve 18 in a valve closing direction (downward in the figure), and a hydraulic pressure. It comprises a fuel supply passage 24 to the piston 22, a three-way valve (electromagnetic valve) 25 interposed in the passage 24, etc. The passages 20 and 24 in the nozzle communicate with each other so that the upper part of the hydraulic piston 22 and the nozzle chamber 19 are both high pressure. When the three-way valve 25 to which fuel is guided is OFF (ports A and B are connected and ports B and C are shut off), since the pressure receiving area of the hydraulic piston 22 is larger than the pressure receiving area of the needle valve 18, the needle valve 18 Although the seat is in a seated state, when the three-way valve 25 is turned on (the ports A and B are shut off and the ports B and C are in communication), the fuel above the hydraulic piston 22 is returned to the fuel tank 11 via the return passage 28, oil The fuel pressure acting on the piston 22 is lowered. As a result, the needle valve 18 rises and fuel is injected from the injection hole at the tip of the nozzle. When the three-way valve 25 is returned to the OFF state again, the high-pressure fuel of the common rail 16 is guided to the hydraulic piston 22 and the fuel injection ends. That is, the fuel injection start timing is adjusted by the switching timing of the three-way valve 25 from OFF to ON, and the fuel injection amount is adjusted by the ON time. If the pressure in the accumulator 16 is the same, the longer the ON time, the more the fuel injection. The amount increases. 26 is a check valve, and 27 is an orifice.
[0028]
The fuel injection device 10 further includes a pressure adjusting valve 31 in the passage 13 for returning the fuel discharged from the supply pump 14 in order to adjust the common rail pressure. The adjustment valve 31 opens and closes the flow path of the passage 13 and adjusts the common rail pressure by adjusting the amount of fuel discharged to the common rail 16. The fuel injection rate changes according to the fuel pressure (injection pressure) of the common rail 16, and the fuel injection rate increases as the fuel pressure of the common rail 16 increases.
[0029]
In a control unit 41 to which signals from an accelerator opening sensor 33, a sensor 34 for detecting an engine speed and a crank angle, a sensor 35 for distinguishing a cylinder, and a water temperature sensor 36 are input, the control unit 41 responds to the engine speed and the accelerator opening. Then, the target fuel injection amount and the target pressure of the common rail 16 are calculated, and the fuel pressure of the common rail 16 is feedback-controlled via the pressure regulating valve 31 so that the common rail pressure detected by the pressure sensor 32 matches this target pressure.
[0030]
In addition to controlling the ON time of the three-way valve 25 in accordance with the calculated target fuel injection amount, and controlling the switching timing of the three-way valve 25 to ON, a predetermined injection start timing according to the operating conditions is obtained. Like that. For example, the fuel injection timing (injection start timing) is delayed up to the piston top dead center (TDC) so that the ignition delay period of the injected fuel becomes longer on the low-rotation low-load side with a high EGR rate. Due to this delay, the temperature in the combustion chamber at the time of ignition is reduced to a low temperature state, and the generation of smoke in the high EGR rate region is suppressed by increasing the premixed combustion ratio. On the other hand, the injection timing is advanced as the rotational speed and the load increase. This is because, even if the ignition delay time is constant, the ignition delay crank angle (a value obtained by converting the ignition delay time into a crank angle) increases in proportion to the increase in the engine speed. The injection timing is advanced to obtain the ignition timing.
[0031]
Returning to FIG. 1, a variable displacement turbocharger is provided in the exhaust passage 2 downstream of the opening of the EGR passage 4. This is provided with a variable nozzle 53 driven by a negative pressure actuator 54 at the scroll inlet of the exhaust turbine 52. The control unit 41 allows the variable nozzle 53 to obtain a predetermined supercharging pressure from a low rotation range. On the low rotation side, the nozzle opening is controlled to increase the flow rate of the exhaust gas introduced into the exhaust turbine 52 (tilted state), and on the high rotation side, the exhaust gas is introduced into the exhaust turbine 52 without resistance to the nozzle opening degree (fully opened state). I do.
[0032]
The negative pressure actuator 54 includes a diaphragm actuator 55 that drives the variable nozzle 53 in response to the control negative pressure, and a negative pressure control valve 56 that adjusts the control negative pressure to the actuator 55. A duty control signal is generated such that the opening ratio becomes a target opening ratio Rvnt obtained as described later, and the duty control signal is output to the negative pressure control valve 56.
[0033]
Now, from the viewpoint of supercharging pressure control, EGR control also physically fulfills the role of supercharging pressure control. That is, by changing the EGR amount, the supercharging pressure also changes. Conversely, when the supercharging pressure is changed, the exhaust pressure changes, so that the EGR amount also changes. Therefore, the supercharging pressure and the EGR amount cannot be controlled independently. In addition, it is somewhat a control disturbance. In addition, if one is changed, in order to ensure control accuracy, the other must be adapted again, but after the other is adapted, the other must be re-adapted. According to the method, it is difficult to secure control accuracy during transition.
[0034]
As described above, the supercharging pressure and the EGR amount affect each other, and when the EGR amount is changed, it is difficult to appropriately adapt the nozzle opening degree, for example, and it is necessary to change the nozzle opening degree. The control unit 41 calculates the target intake air amount tQac according to the operating conditions, and the actual EGR which is a value obtained by delaying the target intake air amount tQac, the target EGR amount, and the target EGR rate Megr. The target opening ratio Rvnt of the variable nozzle 53, which is the operation target value of the turbocharger, is set based on the amount Qec and the actual GR rate Megrd.
[0035]
In addition, in order to prevent the occurrence of smoke during acceleration when the actual EGR rate becomes larger than the target EGR rate, the actual common rail pressure (actual injection pressure) is compared with the target common rail pressure (target injection pressure). If it is lower (during acceleration), the target EGR rate (the control target value of the EGR device) is reduced and corrected.
[0036]
The contents of the control executed by the control unit 41 will be described with reference to the following flowchart. FIGS. 3, 4, and 8 to 14 to be described later are devices of the prior application (see Japanese Patent Application No. 9-92306), and FIG. This is the same as that already proposed in the prior application (see Japanese Patent Application No. 9-125892).
[0037]
First, FIG. 3 is for calculating the target fuel injection amount Qsol, and is an input of a REF signal (a crank angle reference position signal, which is a signal every 180 degrees for a four-cylinder engine and every 120 degrees for a six-cylinder engine). Execute every time.
[0038]
In steps 1 and 2, the engine speed Ne and the accelerator opening Cl are read, and in step 3, a basic fuel injection amount Mqdrv is calculated by searching a map having the contents shown in FIG. 4 based on these Ne and Cl. Then, in step 4, the basic fuel injection amount Mqdrv is increased by the engine cooling water temperature or the like, and the corrected value is set as the target fuel injection amount Qsol.
[0039]
FIG. 5 is for calculating the opening area Aev of the EGR valve 6, and is executed every time the REF signal is input. In step 1, the target EGR amount Tqek is calculated. The calculation of Tqek will be described with reference to the flowchart of FIG.
[0040]
In FIG. 7 (subroutine of step 1 in FIG. 5), in steps 1 and 2, the intake air amount Qacn per cylinder and the target EGR rate Megr are calculated.
[0041]
Here, the calculation of Qacn will be described with reference to the flow of FIG. 8, and the calculation of Megr will be described with reference to the flow of FIG.
[0042]
First, in FIG. 8, in step 1, the engine speed Ne is read, and based on the engine speed Ne and the intake air amount Qas0 obtained from the air flow meter.
[0043]
(Equation 1)
Qac0 = (Qas0 / Ne) × KCON #
Where KCON #: constant,
The intake air amount Qac0 per cylinder is calculated by the following equation.
[0044]
The air flow meter 39 (see FIG. 1) is provided in the intake passage 3 upstream of the compressor, and performs a delay process for a transport delay from the air flow meter 39 to the collector unit 3a. The value of Qac0 before (constant) times is obtained as the intake air amount Qacn per cylinder at the position of the collector inlet 3a. Then, in step 4, this Qacn is
[0045]
(Equation 2)
Qac = Qac_n-1× (1-KIN × KVOL) + Qacn × KIN × KVOL
However, KIN: a value corresponding to volumetric efficiency,
KVOL: VE / NC / VM,
VE: displacement,
NC: Number of cylinders,
VM: intake system volume,
Qac_n-1: Previous Qac,
(First-order lag equation) is used to calculate the intake air amount per cylinder at the intake valve position (this intake air amount is hereinafter abbreviated as “cylinder intake air amount”) Qac. This is for compensating the dynamics from the collector inlet 3a to the intake valve.
[0046]
The detection of the intake air amount Qas0 on the right side of Equation 1 will be described with reference to the flow of FIG. The flow of FIG. 9 is executed every 4 msec.
[0047]
At step 1, the output voltage Us of the air flow meter 39 is read, and at step 2, a voltage-flow rate conversion table having the contents shown in FIG. Calculate d. Further, in step 3, this Qas0 The weighted average processing is performed on d, and the weighted average processing value is set as the intake air amount Qas0.
[0048]
Next, in FIG. 11, in step 1, the engine speed Ne, the target fuel injection amount Qsol, the engine coolant temperature Tw, the target common rail pressure tPrail, and the actual common rail pressure rPrail are read.
[0049]
Here, the target common rail pressure tPrail is basically a value calculated by searching a map having the contents shown in FIG. 67 from the engine speed Ne and the target fuel injection amount Qsol. The actual common rail pressure rPrail is a value detected by the sensor 32 (see FIG. 2).
[0050]
In step 2, the basic target EGR rate Megrb is calculated by searching a map having the contents shown in FIG. 12 from the engine speed Ne and the target fuel injection amount Qsol. In this case, the basic target EGR rate is increased in a region where the engine is frequently used, that is, in a low turning point and a low load (low injection amount), and is reduced at a high output in which smoke is likely to occur.
[0051]
Next, in step 3, a table containing the contents shown in FIG. 13 is retrieved from the cooling water temperature Tw to obtain a water temperature correction coefficient Kegr of the basic target EGR rate. tw is calculated.
[0052]
In step 4, the common rail pressure correction ratio Rdegr is calculated. The calculation of Rdegr will be described with reference to the flow of FIG.
[0053]
In FIG. 68, in step 1, an error Drail of the actual common rail pressure rPrail from the target common rail pressure tPrail is calculated, and a correction coefficient Degr of the common rail pressure error is calculated by searching a map including FIG. 69 from the error. I do. As shown in FIG. 69, the value of Degr increases as the error Drail from the target common rail pressure increases during acceleration when the actual common rail pressure becomes lower than the target common rail pressure (that is, in the region of Drail> 0). is there.
[0054]
In step 3 of FIG. 68, in order to change the sensitivity of the correction depending on the operating conditions, using this correction coefficient Degr and Qsol equivalent to the correction gain,
Rdegr = Degr × Qsol × KERAIL #
Where KERAIL #: constant
The common rail pressure correction ratio Rdegr is calculated by the following equation. This calculated Rdegr is limited between 0 and 1 in step 4, and the process is terminated.
[0055]
Here, Qsol equivalent to the correction gain is introduced to cope with the fact that the amount (sensitivity) to be corrected differs depending on the engine load even for the same injection pressure error (common rail pressure error). For example, during acceleration with a large load, it is necessary to greatly change the common rail pressure to increase the pressure, so that the deviation from the actual common rail pressure is large and smoke is likely to occur (that is, the sensitivity to exhaust is large when the acceleration is large). . On the other hand, during acceleration with a small load, the deviation from the actual common rail pressure is small, so that the sensitivity to exhaust is small. As described above, when the load at the time of acceleration is large, the sensitivity of correction needs to be higher when the load at the time of acceleration is large, and such a requirement can be satisfied. Further, it is possible to cope with a case where the running load changes even in a steady operation such as a slope or a multi-person riding, not only during the acceleration.
[0056]
If it is necessary to change the sensitivity of the correction also with respect to the engine speed, a gain is introduced instead of Qsol, and this gain is calculated according to the operating conditions (Ne, Qsol) (Ne, Qsol is calculated as A map of gain as a parameter may be created in advance).
[0057]
When the calculation of the common rail pressure correction ratio Rdegr is completed in this way, the process returns to FIG. 11, and in step 5, the basic target EGR ratio, the water temperature correction coefficient, and the common rail pressure correction ratio are used.
[0058]
(Equation 3)
Megr = Megrb × Kegr tw × (1-Rdegr)
The target EGR rate Megr is calculated by the following equation. The value of 1−Rdegr is the rate at which the target EGR rate is reduced and corrected.
[0059]
As described above, at the time of acceleration when the actual common rail pressure becomes lower than the target common rail pressure, Rdegr becomes a value of 1 or less, so that (1−Rdegr) in Expression 3 also becomes a value of 1 or less, thereby reducing the target EGR rate. Will be corrected.
[0060]
In step 6, it is determined whether or not the state of the engine is a complete explosion state. However, the determination of the complete explosion will be described later with reference to the flow of FIG.
[0061]
In step 7, it is determined whether the state is complete explosion. If the state is complete explosion, the current processing is terminated as it is. If it is determined that the state is not complete explosion, the target EGR rate Megr is set to 0 and the current processing ends.
[0062]
Thus, EGR control is performed after the complete explosion of the engine, and EGR is not performed before the complete explosion in order to ensure stable startability.
[0063]
FIG. 14 is for determining the complete explosion of the engine. In step 1, the engine speed Ne is read, and the engine speed Ne is compared with the complete explosion determination slice level NRPKM corresponding to the complete explosion speed in step 2. If Ne is larger, it is determined that the explosion is complete, and the process proceeds to step 3. Here, the counter Tmrkb is compared with a predetermined time TRMKBP. If the counter Tmrkb is larger than the predetermined time, the process proceeds to step 4 and the processing is terminated assuming that the explosion has been completed.
[0064]
On the other hand, if Ne is smaller in step 2, the process proceeds to step 6, the counter Tmrkb is cleared, and in step 7, the process is terminated assuming that it is not in the complete explosion state. Further, even if it is larger than Ne in step 2, if the counter Tmrkb is smaller than the predetermined time in step 3, the counter is incremented in step 5 and it is determined that the explosion is not complete.
[0065]
Thus, when the engine speed is equal to or higher than a predetermined value (for example, 400 rpm) and this state is continued for a predetermined time, it is determined that a complete explosion has occurred.
[0066]
After the calculation of the cylinder intake air amount Qacn in FIG. 8 and the target EGR rate Megr in FIG. 11 are completed, the process returns to step 3 in FIG.
[0067]
(Equation 4)
Mqec = Qacn × Megr
The required EGR amount Mqec is calculated by the following equation.
[0068]
In step 4, KIN × KVOL is used as a weighted average coefficient for this Mqec.
[0069]
(Equation 5)
Rqec = Mqec × KIN × KVOL
+ Rqec_n-1× (1-KIN × KVOL)
However, KIN: a value corresponding to volumetric efficiency,
KVOL: VE / NC / VM,
VE: displacement,
NC: Number of cylinders,
VM: intake system volume,
Rqec_n-1: Previous intermediate processing value,
The intermediate processing value (weighted average value) Rqec is calculated by the following equation, and in step 5 using this Rqec and the required EGR amount Mqec.
[0070]
(Equation 6)
Tqec = Mqec × GKQEC + Rqec_n-1× (1-GKQEC)
However, GKQEC: advance correction gain,
The advance correction is performed by the following equation to calculate the target EGR amount Tqec per cylinder. Since there is a delay in the intake system with respect to the required value (that is, a delay corresponding to the EGR valve 6 → the collector unit 3a → the intake manifold → the capacity of the intake valve), steps 4 and 5 perform advancing processing for the delay. .
[0071]
In Step 6
[0072]
(Equation 7)
Tqek = Tqec × (Ne / KCON #) / Kqac00
Here, Kqac00: EGR amount feedback correction coefficient,
KCON #: constant,
The target EGR amount Tqek is obtained by performing unit conversion (per cylinder → per unit time) according to the following equation. The calculation of the EGR amount feedback correction coefficient Kqac00 will be described later (see FIG. 54).
[0073]
When the calculation of the target EGR amount Tqek is completed in this manner, the process returns to step 2 in FIG. Is calculated from the EGR flow speed Cqe and the target EGR amount Tqek.
[0074]
(Equation 8)
Aev = Tqek / Cqe
The EGR valve opening area Aev is calculated by the following equation. The calculation of the EGR flow velocity Cqe will be described later (see FIG. 63).
[0075]
The EGR valve opening area Aev obtained in this manner is converted into a lift amount of the EGR valve 6 by searching a table containing the contents in FIG. 6 in a flow (not shown) or the like, so that the EGR valve lift amount is obtained. A duty control signal for the negative pressure control valve 5 is generated, and the duty control signal is output to the negative pressure control valve 5.
[0076]
Next, FIG. 15 and FIG. 16 are for calculating the control command duty value Dtyvnt given to the negative pressure control valve 56 for driving the turbocharger, and are executed at regular intervals (for example, at every 10 msec).
[0077]
If FIG. 15 is the first embodiment and FIG. 16 is the second embodiment, there is a difference between the two embodiments in the parameters used to calculate the target opening ratio Rvnt of the variable nozzle 53 (the first embodiment in FIG. 15). Then, the target opening ratio Rvnt of the variable nozzle 53 is calculated based on the actual EGR amount Qec, and in the second embodiment in FIG. 16, based on the actual EGR rate Megrd.
[0078]
FIGS. 15 and 16 show a main routine. A large control flow follows the illustrated steps, and a subroutine is prepared for the processing of each step. Therefore, the following description will focus on the subroutine.
[0079]
FIG. 17 (subroutine of step 1 in FIGS. 15 and 16) is for calculating the actual EGR rate, and is executed every time the REF signal is input. In step 1, the target EGR rate Megr (already obtained in FIG. 11) is read, and in step 2, a time constant equivalent value Kkin for the collector capacity is calculated. The calculation of Kkin will be described with reference to the flow of FIG.
[0080]
In FIG. 18 (subroutine of step 2 in FIG. 17), in step 1, the engine speed Ne, the target fuel injection amount Qsol, and Megrd which is the previous value of the actual EGR rate described later._n-1[%], A basic value Kinb equivalent to volumetric efficiency is calculated by searching a map having the contents shown in FIG. 19 in step 2 from Ne and Qsol, and in step 3
[0081]
(Equation 9)
Kin = Kinb × 1 / (1 + Megrd)_n-1/ 100)
The volume efficiency equivalent value Kin is calculated by the following equation. Since the volumetric efficiency is reduced by the EGR, the correction is made accordingly.
[0082]
The value obtained by multiplying the Kin obtained in this manner by KVOL (see step 4 in FIG. 8) which is a constant corresponding to the ratio of the intake system volume to the cylinder volume in step 4 is defined as a time constant equivalent value Kkin for the collector capacity. Calculate.
[0083]
When the calculation of Kkin is completed in this way, the process returns to step 3 in FIG. 17, and using this Kkin and the target EGR rate Megr,
[0084]
(Equation 10)
Megrd = Megr × Kkin × Ne × KE2 # + Megrd_n-1× (1-Kkin × Ne × KE2 #)
However, Kkin: Kin × KVOL #,
KE2 #: constant,
Megrd_n-1: Previous Megrd,
The EGR rate Megrd at the intake valve position is calculated by simultaneously performing the delay processing and the unit conversion (per cylinder / per unit time) by the following equation. Ne × KE2 # on the right side of Expression 10 is a value for unit conversion. Since this Megrd responds to the target EGR rate Megr with a first-order lag (see FIGS. 65 and 66), this Megrd is hereinafter referred to as “actual EGR rate”.
[0085]
FIG. 20 (subroutine of step 2 in FIGS. 15 and 16) is for calculating the target intake air amount tQac. In step 1, the engine speed Ne, the actual EGR rate Megrd, and the target fuel injection amount Qsol are read, and in step 2, Megrd is compared with a predetermined value MEGLVV #.
[0086]
Here, the predetermined value MEGRLV # is a value (for example, 0.5) for determining the presence or absence of the operation of EGR. When Megrd> MEGRLV #, it is determined that the EGR is in the EGR operating range, and Steps 3, 4, and When the condition Megrd ≦ MEGRLV # is satisfied, it is determined that the EGR is in the non-operating range, and the process proceeds to step 6. MEGRLV # is not 0 because there is a request to treat a small amount of EGR in the same way as when EGR is not performed.
[0087]
If it is in the EGR operation range, the target intake air amount basic value tQacb is calculated in step 3 by searching a map having, for example, the contents shown in FIG. 21 from the engine speed Ne and the actual EGR rate Megrd. If the engine speed is constant, the target intake air amount increases as the actual EGR rate increases as shown in FIG.
[0088]
In step 4, a correction coefficient ktQac of the target intake air amount is calculated by searching a map having the contents shown in FIG. 22 from Ne and Qsol, and a value obtained by multiplying the correction coefficient by the target intake air amount basic value is calculated. It is calculated as the target intake air amount tQac. The correction coefficient ktQac is for responding to a request to change the target intake air amount according to the operating conditions (Ne, Qsol).
[0089]
On the other hand, if it is in the EGR non-operating range, the routine proceeds to step 6, where the target intake air amount tQac is calculated by searching a map containing the contents of, for example, FIG. 23 from Ne and Qsol.
[0090]
FIG. 24 (subroutine of step 3 in FIG. 15) is for calculating the actual EGR amount. In step 1, the intake air amount Qacn per cylinder (already obtained in step 3 in FIG. 8) at the position of the collector inlet 3a, the target EGR rate Megr, and the time constant equivalent value Kkin for the collector capacity are read. Of these, from Qacn and Megr in step 2
[0091]
[Equation 11]
Qec0 = Qacn × Megr
The EGR amount Qec0 per cylinder at the position of the collector inlet portion 3a is calculated by the following equation, and using this Qec0 and Kkin, in step 3,
[0092]
(Equation 12)
Qec = Qec0 × Kkin × Ne × KE # + Qec_n-1× (1-Kkin × Ne × KE #)
However, Kkin: Kin × KVOL,
KE #: constant,
Qec_n-1: Previous Qec,
In the same manner as in the above equation (10), delay processing and unit conversion (per cylinder / per unit time) are simultaneously performed to calculate the cylinder intake EGR amount Qec. Ne × KE # on the right side of Expression 12 is a value for unit conversion. Since this Qec responds to the target EGR amount Tqek with a first-order delay, this Qec is hereinafter referred to as “actual EGR amount”. The above-described Qac that responds to the target intake air amount tQac with a first-order delay is hereinafter referred to as “actual intake air amount” (see FIGS. 65 and 66).
[0093]
FIG. 25 (subroutine of step 4 in FIG. 15) and FIG. 27 (subroutine of step 3 in FIG. 16) are for calculating the target opening ratio Rvnt of the variable nozzle 53 (FIG. 25 is the first embodiment, FIG. 27 is the second embodiment).
[0094]
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, when the variable nozzle 53 is fully opened, the opening ratio is 100%, and when the variable nozzle 53 is fully closed, the opening ratio is 0%. The reason why the opening ratio is adopted is to provide versatility (a value irrelevant to the capacity of the turbocharger). Of course, the opening area of the variable nozzle may be adopted.
[0095]
Note that the turbocharger of the embodiment is of a type in which the supercharging pressure is the smallest when fully opened and the supercharging pressure is the highest when fully closed, so that the smaller the opening ratio, the higher the supercharging pressure.
[0096]
First, from FIG. 25 of the first embodiment, in step 1, the target intake air amount tQac, the actual EGR amount Qec, the engine speed Ne, and the target fuel injection amount Qsol are read.
[0097]
In steps 2 and 3,
[0098]
(Equation 13)
tQas0 = (tQac + Qsol × QFGAN #) × Ne / KCON #
Qes0 = (Qec + Qsol × QFGAN #) × Ne / KCON #
However, QFGAN #: gain,
KCON #: constant,
The two equations are used to set the target opening ratio in the same manner as the intake air amount equivalent value tQas0 for setting the target opening ratio (hereinafter, this intake air amount equivalent value is referred to as “set intake air amount equivalent value”). An EGR amount equivalent value Qes0 (hereinafter, this EGR amount equivalent value is referred to as a “set EGR amount equivalent value”) is calculated. In equation (13), the reason why Qsol × QFGAN # is added to tQac and Qec is that load correction can be performed for the set intake air amount equivalent value and the set EGR amount equivalent value, and the sensitivity is set to the gain QFGAN #. It is to be adjusted by. Ne / KCON # is a value for converting into an intake air amount and an EGR amount per unit time.
[0099]
From the set intake air amount equivalent value tQas0 and the set EGR amount equivalent value tQes0 thus determined, in step 4, a target opening ratio Rvnt of the variable nozzle 53 is set by searching, for example, a map having the contents shown in FIG.
[0100]
On the other hand, in FIG. 27 of the second embodiment, in step 1, the target intake air amount tQac, the actual EGR rate Megrd, the engine speed Ne, and the target fuel injection amount Qsol are read. The set intake air amount equivalent value tQas0 is calculated by the upper equation, and the target of the variable nozzle 53 is obtained by searching a map having the contents shown in FIG. 28 in step 3 from the set intake air amount equivalent value tQas0 and the actual EGR rate Megrd. An opening ratio Rvnt is set.
[0101]
The characteristics shown in FIGS. 26 and 28 are set with emphasis on fuel efficiency. However, since the difference from the exhaust-oriented setting example described later is only a specific numerical value, the characteristics common to both are described first, and then the difference between them is described. The characteristics in FIG. 28 are different from those in FIG. 26 (the inclination from the origin indicates the EGR rate in FIG. 26), but are basically the same as those in FIG. .
[0102]
As shown in FIG. 26, in the right region where the set intake air amount equivalent value tQas0 is large, the target opening ratio decreases as the set EGR amount equivalent value Qes0 increases. This is for the following reason. When the EGR amount increases, fresh air decreases by that amount, and when the air-fuel ratio leans to the rich side, smoke is generated. Therefore, as the EGR amount increases, it is necessary to reduce the target opening ratio and increase the supercharging pressure.
[0103]
On the other hand, in the small left region of tQas0, the supercharging effect is not so much obtained. In this region, the smaller the tQas0, the smaller the target opening ratio. This is for the following reason. This is because, if the target opening ratio is increased even in this region, it is difficult to raise the exhaust pressure, so that it is desired to avoid this. Also, for full-open acceleration, it is better that the opening ratio is small in the initial stage. As described above, the characteristic shown in FIG. 26 is basically determined from two different requirements. Therefore, the change in the target opening ratio differs between a case where the change in the target intake air amount is small and a case where the change is large (see FIGS. 65 and 66).
[0104]
By the way, the tendency of the target opening ratio represented in FIG. 26 is common to the emphasis on fuel efficiency and the exhaust, and the difference between them is a specific numerical value. In the figure, the numerical value of the position "small" is the minimum value at which the turbocharger works efficiently, and is the same as the setting example focusing on fuel consumption and the setting example focusing on exhaust, for example, about 20. On the other hand, the numerical value of the position "large" differs between the two, and is about 60 in the case of the setting example focusing on fuel consumption, and about 30 in the setting example focusing on exhaust.
[0105]
The setting of the target opening ratio is not limited to the above. In the first embodiment, the target opening ratio is set based on the set intake air amount equivalent value tQas0 and the set EGR amount equivalent value tQes0. Instead, the target opening ratio is set based on the target intake air amount tQac and the actual EGR amount Qec. It doesn't matter. Further, instead of this, the target intake air amount tQac and the target EGR amount (Qec0) may be set. Similarly, in the second embodiment, the target opening ratio is set based on the set intake air amount equivalent value tQas0 and the actual EGR rate Megrd. Instead, the target opening ratio is set based on the target intake air amount tQac and the actual EGR rate Megrd. It doesn't matter. Further, instead of this, the target intake air amount tQac and the target EGR rate Megr may be set.
[0106]
FIG. 29 (the subroutine of step 5 in FIG. 15 and step 4 in FIG. 16) is based on the target nozzle opening ratio Rvnt obtained as described above. In order to compensate for the dynamics of the diaphragm actuator 55), advance processing is performed. This is because, when the actuator of the variable nozzle 53 is a negative pressure actuator, unlike the case of a step motor, there is a response delay that cannot be ignored.
[0107]
In step 1, the target opening ratio Rvnt is read, and this Rvnt and the previous expected opening ratio Cavnt are read._n-1Are compared in step 2. Here, the expected opening ratio Cavnt is a weighted average value of the target opening ratio Rvnt, as will be described later (see step 10).
[0108]
Rvnt> Cavnt_n-1If (if the variable nozzle 53 is being moved to the open side), the process proceeds to steps 3 and 4, where the predetermined value GKVNTO # is set as the advance correction gain Gkvnt, and the predetermined value TCVNTO # is set as the time constant equivalent value Tcvnt of the advance correction. , Whereas Rvnt <Cavnt_n-1(When the variable nozzle 53 is being moved to the closing side), the process proceeds to steps 6 and 7, where the predetermined value GKVNTC # is advanced and the correction gain Gkvnt is set, and the predetermined value TCVNTC # is set as the time constant equivalent value Tcvnt for advanced correction. I do. Also, Rvnt and Cavnt_n-1If they are the same, the process proceeds to steps 8 and 9 to maintain the preceding advance correction gain and the value corresponding to the time constant of advance correction.
[0109]
The advance correction gain Gkvnt and the time constant equivalent value Tcvnt of advance correction differ between when the variable nozzle 53 is moving to the open side and when it is moving to the close side, and GKVNTO # <GKVNTC # and TCVNTO # <TCVNTC #. I have. This is because when moving the variable nozzle 53 to the closing side, it is necessary to withstand the exhaust pressure, so that the gain Gkvnt is increased and the time constant is reduced accordingly (corresponding to the time constant which is inversely related to the time constant). This is because the value Tcvnt needs to be increased.
[0110]
In step 10, using the time constant equivalent value Tcvnt and the target opening ratio Rvnt obtained in this manner,
[0111]
[Equation 14]
Cavnt = Rvnt × Tcvnt + Cavnt_n-1× (1-Tcvnt)
However, Cavnt_n-1: Previous Cavnt,
The expected opening ratio Cavnt is calculated by the following equation, and from this value and the target opening ratio Rvnt, in step 11,
[0112]
(Equation 15)
Avnt f = Gkvnt × Rvnt− (Gkvnt−1) × Cavnt_n-1
However, Cavnt_n-1: Previous Cavnt,
The advance correction is performed according to the following equation, and the feedforward amount Avnt of the target opening ratio is calculated. Calculate f. The advance processing itself in steps 10 and 11 is basically the same as the advance processing shown in steps 4 and 5 in FIG.
[0113]
30 (each subroutine of step 6 in FIG. 15 and step 5 in FIG. 16) is a feedback amount Avnt of the target opening ratio. This is for calculating fb. In step 1, the target intake air amount tQac, the target EGR rate Megr, the engine speed Ne, the target fuel injection amount Qsol, and the actual intake air amount Qac are read, and in step 2, the target EGR rate Megr is compared with a predetermined value MEGLV #.
[0114]
When Megr ≧ MEGRLV # (when the operating range of EGR is satisfied), in step 4,
[0115]
(Equation 16)
dQac = tQac / Qac-1
The error ratio dQac from the target intake air amount is calculated by the following equation. The value of dQac is centered on 0, and becomes a positive value when Qac as an actual value is smaller than tQac as a target value, and becomes a negative value when Qac is larger than tQac.
[0116]
On the other hand, when Megr <MEGRLV # (when the EGR is in the non-operating range), the process proceeds to step 3, where the error ratio dQac = 0 (that is, feedback is prohibited).
[0117]
In step 5, the correction coefficient Kh of the feedback gain is calculated by searching a predetermined map from Ne and Qsol, and this value is converted into each constant (proportional constant KPB #, integral constant KIB #, differential constant KDB #) in step 6. The feedback gains Kp, Ki, and Kd are calculated by multiplying them, and the feedback amount Avnt of the target opening ratio is calculated using these values. fb is calculated in step 7. The method of calculating the feedback amount is a well-known PID process.
[0118]
The correction coefficient Kh is introduced in response to a change in the appropriate feedback gain depending on the operating conditions (Ne, Qsol), and increases as the load and the rotation speed increase.
[0119]
FIG. 31 (each subroutine of step 7 in FIG. 15 and step 6 in FIG. 16) is for performing linearization processing on the target aperture ratio. In step 1, the feedforward amount Avnt of the target opening ratio f and feedback amount Avnt fb is read, and a value obtained by adding the two in step 2 is calculated as the command opening ratio Avnt. In step 3, a command opening ratio linearization processing value Ratdty is set by searching a table (linearization table) having the contents shown in FIG. 32, for example, from the command opening ratio Avnt.
[0120]
This linearization processing is necessary when the command signal to the actuator for driving the turbocharger has a non-linear characteristic with respect to the opening ratio (or opening area) as shown in FIG. For example, as shown in FIG. 33, even if the change width of the air amount (supercharging pressure) is the same, the change width of the opening area is significantly different from dA0 and dA1 in the region having a small air amount and the region having a large air amount ( However, when there is no EGR). Further, the width of change of the opening area also changes depending on the presence or absence of EGR (in the figure, “w / o EGR” indicates no EGR, and “w / EGR” indicates that EGR is present). Therefore, a target intake air amount (supercharging pressure) cannot be obtained if the same feedback gain is used regardless of operating conditions. Therefore, in order to facilitate the adaptation of the feedback gain, the correction coefficient Kh of the feedback gain according to the operating condition is introduced as described above.
[0121]
FIG. 34 (each subroutine of step 8 in FIG. 15 and step 7 in FIG. 16) is for setting a control command value Dtyvnt which is an ON duty value (hereinafter simply referred to as “duty value”) to be given to the negative pressure control valve 56. Things. First, in step 1, an engine speed Ne, a target fuel injection amount Qsol, a command opening ratio linearization processing value Ratdty, a time constant equivalent value Tcvnt for advance correction, and a water temperature Tw are read.
[0122]
In step 2, a duty selection signal flag is set. This flag setting will be described with reference to the flow of FIG. In FIG. 35, at step 1, the command opening ratio Avnt and the time constant equivalent value Tcvnt of advance correction are read.
[0123]
[Equation 17]
Adlyvnt = Avnt × Tcvnt + Adlyvnt_n-1× (1-Tcvnt)
However, Addlyvnt_n-1: The previous Addlyvnt,
The expected opening ratio Adlyvnt is calculated by performing delay processing according to the following equation, and this value is compared with the previous expected opening ratio M (where M is a constant) times the value of Adlyvnt._n-MAre compared in step 3.
[0124]
Addlyvnt ≧ Adlyvnt_n-M(When it is increasing or in a steady state), the operation direction command flag fvnt is set to 1 in step 4 to indicate that it is increasing or in the steady state. Set to 0. In step 6, Adlyvnt and Adlyvnt are used in order to separate the case of a further increase from the steady state._n-MAre compared, and Adlyvnt = Adlyvnt_n-MIs satisfied, the duty holding flag fvnt2 is set to 1 in step 7; otherwise, the duty holding flag fvnt2 is set to 0 in step 8.
[0125]
When the setting of the two flags fvnt and fvnt2 is completed in this way, the flow returns to step 3 of FIG. 34, and the temperature correction amount Dty of the duty value is set. Calculate t. This calculation will be described with reference to the flowchart of FIG.
[0126]
In FIG. 36, the engine speed Ne, the target fuel injection amount Qsol, and the water temperature Tw are read in step 1, and the basic exhaust gas temperature Texhb is retrieved from the Ne and Qsol in step 2 by searching, for example, a map having the contents shown in FIG. Is calculated. Here, Texhb is the exhaust gas temperature after completion of warm-up. On the other hand, during warm-up, the exhaust temperature differs from the exhaust temperature after the warm-up is completed. Ktexh tw is calculated, and a value obtained by multiplying this value by the above-described basic exhaust gas temperature in step 4 is calculated as an exhaust gas temperature Texhi.
[0127]
In step 5, from this exhaust temperature Texhi
[0128]
(Equation 18)
Texhdly = Texhi × KEXH # + Texhdly_n-1× (1-KEXH #)
Where KEXH #: constant,
Texhdly_n-1: The last Texhdly,
Is calculated as the actual exhaust gas temperature Texhdly. This is to perform delay processing for the thermal inertia.
[0129]
In step 6, a difference dTexh between the basic exhaust gas temperature Texhb and the actual exhaust gas temperature Texhdly is calculated, and a temperature correction amount Dty of the duty value is obtained from the difference dTexh in step 7 by, for example, searching a table having the contents shown in FIG. Calculate t. Steps 6 and 7 correspond to a map (Duty) used for hysteresis described later. h p, Duty h n, Duty l p, Duty l n is set with respect to the state after completion of warm-up, and a correction amount corresponding to a difference from that state (that is, dTexh) is provided. Note that the temperature correction amount Dty The correction based on t is a process required when using a turbocharger driving actuator having a temperature characteristic depending on the ambient temperature (see FIG. 40).
[0130]
Thus, the temperature correction amount Dty When the calculation of t is completed, the process returns to step 4 of FIG.
[0131]
Steps 4 to 9 in FIG. 34 perform a hysteresis process. This process will be described earlier with reference to FIG. 45. This is because when the command opening ratio linearization processing value Ratdty tends to increase, the upper characteristic (Duty) is obtained. l p is a command signal when the variable nozzle is fully opened, Duty h When the command opening ratio linearization processing value Ratdty tends to decrease while p is a command signal when the variable nozzle is fully closed, the other lower characteristic (Duty) is used. l n is a command signal when the variable nozzle is fully opened, Duty hnIs used as a command signal when the variable nozzle is fully closed. In addition, there is a region where the Ratdty is close to 1 and two characteristics are turned upside down, but this region is not actually used.
[0132]
Returning to FIG. 34, in step 4, the flag fvnt1 is checked. When fvnt = 1 (that is, when the opening ratio is increasing or in a steady state), the process proceeds to Steps 5 and 6, and for example, a map (Duty) including FIG. h p map) and a map (Duty) containing FIG. l p map) to obtain the duty value Duty when the variable nozzle is fully closed. h and duty value when the variable nozzle is fully open Set l respectively. On the other hand, when fvnt = 0 (that is, when the opening ratio is in a decreasing trend), the process proceeds to steps 7 and 8, and for example, a map (Duty) having the contents shown in FIG. h n map) and a map (Duty) containing FIG. l n map) to obtain the duty value Duty when the variable nozzle is fully closed. h and duty value when the variable nozzle is fully open Set l respectively.
[0133]
The duty value Duty when the variable nozzle is fully closed set in this way. h, Duty value when variable nozzle is fully open In step 9 using l and the above-mentioned command opening ratio linearization processing value Ratdty,
[0134]
(Equation 18)
Dty h = (Duty h-Duty l) × Rattty + Duty l + Dty t
The command duty value basic value Dty is calculated by performing linear interpolation calculation according to the following equation. Calculate h. That is, the characteristics of the straight line used for the linear interpolation calculation are changed between when the command opening ratio linearization processing value is increasing or in a steady state and when the command opening ratio linearization processing value is decreasing ( By performing the hysteresis process), even if the command opening ratio linearization processing value is the same, the command opening ratio linearization processing value is more likely to increase when the command opening ratio linearization processing value (or in a steady state) is reduced than when it is decreasing. Duty value basic value Dty h increases.
[0135]
In step 10, another flag fvnt2 is checked. If fvnt2 = 1 (that is, there is no change in the command opening ratio linearization processing value), the process proceeds to step 11, where Dtyvnt is the previous control command duty value (described later)._n-1Is input to the normal command duty value Dtyv (duty value is held), and when fvnt2 = 0 (that is, the opening ratio is decreasing), the process proceeds to step 12, where Dty which is the latest calculation value is obtained. Let h be Dtyv.
[0136]
In step 13, an operation confirmation control process is performed. This processing will be described with reference to the flow in FIG. In FIG. 46, in step 1, the normal command duty value Dtyv, the engine speed Ne, the target fuel injection amount Qsol, and the water temperature Tw are read.
[0137]
The condition for entering the operation confirmation control is determined by checking the contents of steps 2, 3, 4, and 5 one by one, and when all of the items are satisfied, the time until the control is further executed is measured. enter. That is,
Step 2: Qsol is less than a predetermined value QSOLDIZ # (that is, at the time of fuel cut)
Step 3: Ne is less than a predetermined value NEDIZ # (that is, middle rotation range)
Step 4: Tw is less than a predetermined value TWDIZ # (that is, before the completion of warm-up)
Step 5: Operation confirmation control completed flag fdiz = 0 (operation confirmation control has not been performed yet),
At this time, in step 6, the operation check control counter Ctrdiz is incremented.
[0138]
In step 7, the operation check control counter is compared with predetermined values CTRDIZH # and CTRDIZL #. Here, the predetermined values CTRDIZL # and CTRDIZH # determine the lower limit and the upper limit of the operation check control counter, respectively. Therefore, from the timing when the operation check control counter matches the lower limit CTRDIZL #, the process proceeds to step 9 while the operation check control counter is less than the upper limit CTRDIZH # to set the operation check control command duty value. That is, CTRDIZH # -CTRDIZL # is the operation confirmation control execution time.
[0139]
The setting of the operation check control command duty value will be described with reference to the flow of FIG. In FIG. 47, the operation confirmation control counter Ctrdiz and the engine speed Ne are read in step 1 and the control pattern Duty is searched in step 2 by searching, for example, a table including FIG. 48 from Ctrdiz-CTRDIZL # (≧ 0). Set pu. This is to move the variable nozzle 53 between the fully closed position and the fully opened position in a short cycle.
[0140]
In step 3, the duty value Duty is searched by searching a table containing, for example, FIG. 49 from the engine speed Ne. p ne, and set this Duty p ne in step 4 the above control pattern Duty The value multiplied by pu is calculated as the control command duty value Dtyvnt. As shown in FIG. 49, the control pattern Duty Duty value to multiply pu p ne is a value corresponding to the engine speed Ne. This is based on the assumption that the duty command value for confirming the opening / closing operation of the variable nozzle 53 differs depending on the engine speed. For example, the variable nozzle 53 needs to be closed against the exhaust pressure, but the exhaust pressure increases as the rotation speed increases, and accordingly, the duty command value is increased. Further, on the high rotation speed side, the value is reduced so as not to be adversely affected by this control.
[0141]
Referring back to FIG. 46, when the operation check control counter is less than CTRDIZL # as the lower limit, the process proceeds from step 8 to step 15, where the normal command duty value Dtyv is set to the control command duty value Dtyvnt.
[0142]
When the operation check control counter becomes equal to or more than CTRDIZH # as the upper limit, the process proceeds from step 7 to step 10, and the previous operation check control counter Ctrdiz_n-1And CTRDIZH # as the upper limit. Ctrdiz_n-1If <CTRDIZH #, it is determined that the operation check control counter has just reached or exceeded CTRDIZH # as the upper limit, and the operation check control is terminated. Therefore, in step 11, the control command duty value Dtyvnt = 0 is set. This is because the variable nozzle 53 is fully opened once at the end of the operation check control to ensure control accuracy during normal control. In step 12, the operation confirmation completed flag fdiz = 1 is set, and the current process ends. Because of the flag fdiz = 1, it is not possible to proceed to step 6 and subsequent times from the next time, so that the operation confirmation control is not performed twice after the engine is started.
[0143]
If it is not immediately after the operation check control counter becomes equal to or more than CTRDIZH # as the upper limit, the process proceeds from step 10 to step 14, sets the operation check control counter Ctrdiz = 0 to prepare for the next time, and then executes the process of step 15. .
[0144]
On the other hand, when Qsol is equal to or more than a predetermined value QSOLDIZ # (not during fuel cut), when Ne is equal to or more than a predetermined value NEDIZ # (high rotation range), Tw is equal to or more than a predetermined value TWDIZ # (after completion of warm-up). At this time, in order to prohibit the operation check control, the process proceeds from Steps 2, 3, and 4 to Step 13, sets the flag fdiz = 0, and executes the processes of Steps 14 and 15.
[0145]
As described above, the operation of the variable turbo nozzle is made smooth by performing the operation confirmation control when the operation of the turbocharger driving actuator is unstable, especially at a low temperature, and the operation of the turbocharger driving actuator is performed. Can be made more reliable.
[0146]
This is the end of the description of FIG. 15 and FIG.
[0147]
Next, FIG. 50 is for calculating two feedback correction coefficients Kqac00, Kqac0 and an EGR flow rate learning correction coefficient Kqac used for the calculation of the EGR amount and the calculation of the EGR flow rate, and are executed every time the REF signal is input.
[0148]
First, in step 1, the target intake air amount tQac, the actual intake air amount Qac, the engine speed Ne, and the target fuel injection amount Qsol are read. In step 2, the target intake air amount tQac
[0149]
[Equation 19]
tQacd = tQac × KIN × KVOL × KQA # + tQacd_n-1× (1-KIN × KVOL × KQA #)
However, KIN: a value corresponding to volumetric efficiency,
KVOL: VE / NC / VM,
VE: displacement,
NC: Number of cylinders,
VM: intake system volume,
KQA #: constant,
tQacd_n-1: Previous Qacd,
The target intake air amount delay processing value tQacd is calculated by the following equation (first-order equation). This is a delay process performed so that two feedback correction coefficients Kqac00 and Kqac0 and a learning value Rqac, which will be described later, do not become large due to a delay in air supply due to the presence of the intake system volume.
[0150]
In step 3, various feedback-related flags are read. These settings will be described with reference to the flowcharts of FIGS. 51, 52, and 53.
[0151]
51, 52, and 53 are executed at regular time intervals (for example, every 10 msec) independently of FIG.
[0152]
FIG. 51 is for setting the feedback permission flag fefb. In step 1, the engine speed Ne, the target fuel injection amount Qsol, the actual EGR rate Megrd, and the water temperature Tw are read.
[0153]
The determination of the feedback permission condition is performed by checking the contents of steps 2 to 5 and 8 one by one, and the feedback is permitted when all of the items are satisfied, and the feedback is prohibited when even one is not satisfied. . That is,
Step 2: Megrd exceeds a predetermined value MEGRFB # (that is, the operating range of EGR);
Step 3: Tw exceeds a predetermined value TWFBL # (for example, about 30 ° C.)
Step 4: Qsol exceeds a predetermined value QSOLFBL # (no fuel cut),
Step 5: Ne is greater than a predetermined value NEFBL # (the engine is not in the engine revolution range).
Step 8: The feedback start counter Ctrfb exceeds a predetermined value TMRFB # (for example, a value of less than one second).
At this time, in step 9, the feedback permission flag fefb = 1 is set to permit the feedback, otherwise, the process proceeds to step 10, where the feedback permission flag fefb = 0 is set to prohibit the feedback.
[0154]
The feedback start counter counts up when steps 2 to 5 are satisfied (step 6), and resets the feedback start counter when steps 2 to 5 are not satisfied (step 7).
[0155]
FIG. 52 is for setting the learning value reflection permission flag felrn2. In step 1, the engine speed Ne, the target fuel injection amount Qsol, the actual EGR rate Megrd, and the water temperature Tw are read.
[0156]
The determination of the learning value reflection permission condition is also performed by checking the contents of steps 2 to 5 and 8 one by one, and when all the items are satisfied, the reflection of the learning value is permitted, and when even one of the items is not satisfied. Prohibits the reflection of the learning value. That is,
Step 2: Megrd exceeds a predetermined value MEGRLN2 # (that is, an EGR operation range),
Step 3: Tw exceeds a predetermined value TWLNL2 # (for example, about 20 ° C.)
Step 4: Qsol exceeds a predetermined value QSOLLLNL2 # (no fuel cut),
Step 5: Ne exceeds a predetermined value NELNL2 # (not in a rotation range where engine stalls)
Step 8: The learning value reflection counter Ctrln2 exceeds a predetermined value TMRLN2 # (for example, about 0.5 seconds).
At this time, in step 9, the learning value reflection permission flag feln2 = 1 is set to permit the reflection of the learning value. Otherwise, the process proceeds to step 10, where the learning value reflection permission flag feln2 = 0 is set to prohibit the reflection of the learning value. I do.
[0157]
The learning value reflection counter is incremented when steps 2 to 5 are satisfied (step 6), and is reset when steps 2 to 5 are not satisfied (step 7).
[0158]
FIG. 53 is for setting the learning permission flag felrn. In step 1, the engine speed Ne, the target fuel injection amount Qsol, the actual EGR rate Megrd, and the water temperature Tw are read.
[0159]
The determination of the learning permission condition is performed by checking the contents of steps 2 to 7 and 10 one by one, and the learning is permitted when all of the items are satisfied, and the learning is prohibited when even one is not satisfied. . That is,
Step 2: Megrd exceeds a predetermined value MEGRLN # (that is, an EGR operation range);
Step 3: Tw exceeds a predetermined value TWLNL # (for example, about 70 to 80 ° C.)
Step 4: Qsol exceeds a predetermined value QSOLLLNL # (no fuel cut),
Step 5: Ne exceeds a predetermined value NELNL # (not in a rotation range where engine stops)
Step 6: Feedback permission flag fefb = 1.
Step 7: The learning value reflection permission flag felrn2 = 1.
Step 10: The learning delay counter Ctrln exceeds a predetermined value TMRLN # (for example, about 4 seconds).
At this time, the learning permission flag feln = 1 is set to permit the learning in step 11, otherwise, the process proceeds to step 12, where the learning permission flag feln = 0 is set to prohibit the learning.
[0160]
The learning delay counter counts up when steps 2 to 7 are satisfied (step 8) and resets when steps 2 to 7 are not satisfied (step 9).
[0161]
Referring back to FIG. 50, of the three flags set in this way, the feedback permission flag fefb is checked in step 4. When fefb = 1, in steps 5 and 6, a feedback correction coefficient Kqac00 for the EGR amount and a feedback correction coefficient Kqac0 for the EGR flow velocity are calculated. On the other hand, when fefb = 0 (when feedback is prohibited), the process proceeds from step 4 to steps 7 and 8, where Kqac00 = 1 and Kqac0 = 1.
[0162]
Here, the calculation of the EGR amount feedback correction coefficient Kqac00 will be described with reference to the flow of FIG. 54, and the calculation of the EGR flow velocity feedback correction coefficient Kqac0 will be described with reference to the flow of FIG.
[0163]
First, in FIG. 54 (subroutine of step 5 in FIG. 50), in step 1, the target intake air amount delay processing value tQacd, the actual intake air amount Qac, the engine speed Ne, the target fuel injection amount Qsol, and the water temperature Tw are read.
[0164]
In step 2, the correction gain Gkfb for the EGR flow rate is retrieved from Ne and Qsol, for example, by searching a map containing the contents shown in FIG. 55, and in step 3, the water temperature correction coefficient Kgfbtw for the correction gain is made from Tw in FIG. 56, for example. Each is calculated by searching a table, etc., and these are used in step 4
[0165]
(Equation 20)
The EGR amount feedback correction coefficient Kqac00 is calculated by the following equation: Kqac00 = (tQacd / Qac-1) × Gkfb × Kgfbtw + 1.
[0166]
(TQacd / Qac-1) in the first term on the right side of this equation is an error ratio from the target intake air amount delay processing value. By adding 1 to this, Kqac00 becomes a value centered at 1. Equation 20 calculates the EGR amount feedback correction coefficient Kqac00 in proportion to the error ratio from the target intake air amount delay processing value.
[0167]
Next, in FIG. 57 (subroutine of step 6 in FIG. 50), in step 1, the target intake air amount delay processing value tQacd, the actual intake air amount Qac, the engine speed Ne, the target fuel injection amount Qsol, and the water temperature Tw are read.
[0168]
In step 2, the correction gain Gkfbi of the EGR flow velocity is obtained by searching a map containing the contents of FIG. 58 from Ne and Qsol, and in step 3, the water temperature correction coefficient Kgfbitw of the correction gain is made of Tw from FIG. 59, for example. Each is calculated by searching a table, etc., and these are used in step 4
[0169]
(Equation 21)
Rqac0 = (tQacd / Qac−1) × Gkfbi × kGfbitw + Rqac0_n-1
However, Rqac0_n-1: Previous Rqac0,
The error ratio Rqac0 is updated by the following equation, and a value obtained by adding 1 to the error ratio Rqac0 in step 5 is calculated as the EGR flow velocity feedback correction coefficient Kqac0.
[0170]
This is to calculate the EGR flow velocity feedback correction coefficient Kqac0 in proportion to the integrated value (integral value) of the error ratio (tQacd / Qac-1) from the target intake air amount delay processing value (integral control).
[0171]
The reason why the correction gain is set to a value corresponding to the operating condition (Ne, Qsol) as shown in FIGS. 55 and 58 is as follows. Even if the gain is the same, hunting may or may not occur depending on the operating conditions. Therefore, in a region where hunting occurs, the correction gain is reduced. The reason why the value is reduced at the time of low water temperature (before completion of warm-up) as shown in FIGS. 56 and 59 is to stabilize the engine in a low water temperature region where engine rotation is unstable.
[0172]
When the calculation of the EGR amount feedback correction coefficient Kqac00 and the EGR flow velocity feedback correction coefficient Kqac0 is completed in this way, the process returns to FIG. 50, and in step 9, the learning value reflection permission flag felrn2 is checked. If the learning reflection permission flag feldrn2 = 1 (when the reflection of the learning value is permitted), the process proceeds to step 10, and the error rate learning value Rqac is read out by searching the learning map of FIG. 60 from Ne and Qsol, for example. Is calculated as an EGR flow velocity learning correction coefficient Kqac. On the other hand, when the learning reflection permission flag feldrn2 = 0 (when the reflection of the learning value is prohibited), the process proceeds from step 9 to step 12, where the EGR flow velocity learning correction coefficient Kqac = 1.
[0173]
Subsequently, in step 13, the learning permission flag feldrn is checked. If the learning permission flag feldrn = 1 (when learning is permitted), the routine proceeds to step 14, where 1 is subtracted from the EGR flow velocity feedback correction coefficient Kqac0 to obtain an error ratio Rqacn. On the other hand, when the learning permission flag feldrn = 0 (when learning is prohibited), the process proceeds from step 13 to step 15, where the error ratio Rqacn = 0.
[0174]
In step 16, the error ratio learning value Rqac is updated based on the error ratio Rqacn thus obtained. The updating of the learning value will be described with reference to the flow of FIG.
[0175]
In FIG. 61 (subroutine of step 16 in FIG. 50), in step 1, the error ratio Rqacn, the engine speed Ne, and the target fuel injection amount Qsol are read. At step 2, the learning speed Tclrn is calculated from Ne and Qsol by, for example, searching a map having the contents shown in FIG. In step 3, an error rate learning value Rqac is read from Ne and Qsol from the learning map of FIG. In step 4
[0176]
(Equation 22)
Rqac_n= Rqacn × Tclrn + Rqac_n-1× (1-Tclrn)
However, Rqac_n: Error ratio learning value after update,
Rqac_n-1: Learning value of error ratio before updating (= reading value of learning value),
The weighted averaging process is performed according to the following equation, and the updated learning value is stored in the learning map in FIG. 60 in step 5 (the value before updating is overwritten on the value before updating).
[0177]
FIG. 63 (subroutine of step 2 in FIG. 5) is for calculating the EGR flow velocity Cqe.
[0178]
In steps 1 and 2, the actual EGR amount Qec, the actual EGR rate Megrd, the actual intake air amount Qac, the EGR flow velocity feedback correction coefficient Kqac0, and the EGR flow velocity learning correction coefficient Kqac are read.
[0179]
(Equation 23)
Qec h = Qec × Kqac × Kqac0
The value obtained by correcting the actual EGR amount Qec with Kqac0 and Kqac is calculated by the following equation. h, and the corrected actual EGR amount Qec In step 8, the EGR flow velocity Cqe is calculated by searching a map having the contents shown in FIG. 64 based on h and the actual EGR rate Megrd. Steps 4 to 7 not described will be described later.
[0180]
The characteristic of the EGR flow velocity in FIG. 64 indicates that the sensitivity of the EGR feedback is different depending on the operating conditions because the nonlinearity is strong, and thus the EGR flow velocity feedback is adjusted so that the difference in the feedback amount with respect to the operating conditions is reduced. The correction coefficient Kqac0 is used as feedback to the actual EGR amount Qec used for searching the flow velocity map.
[0181]
However, in FIG. 64, the portion near the right end where the slope of the characteristic becomes steep is a region in which a matching error of the map is likely to occur. Therefore, if there is a matching error, the EGR valve opening area Aev is affected by the matching error. Changes. In other words, since Aq = Tqek / Cqe, which is a formula for calculating the EGR valve opening area Aev, causes a matching error in Cqe. To deal with this, correction of the flow rate error is also performed on the target EGR amount Tqek. Need to do. Therefore, the newly introduced EGR amount feedback correction coefficient Kqac00 is used to correct the target EGR amount Tqek in step 6 of FIG.
[0182]
In this case, the above equation (20) for calculating Kqac00 calculates Kqac00 in proportion to the error rate from the target intake air amount delay processing value. Therefore, the proportional error of the EGR flow velocity map in FIG. Can be corrected immediately. For example, in Equation 20, for simplicity, Kqac00 = (tQacd / Qac-1) +1 when the correction gain Gkfb = 1 and the warm-up is completed. In this case, if the actual intake air amount Qac is smaller than tQacd as the target value, Kqac00 becomes a value larger than 1, whereby Tqec is immediately reduced. When the target EGR amount is immediately reduced, the fresh air amount (intake air amount) relatively increases, whereby the actual intake air amount Qac converges to tQacd as the target value.
[0183]
Steps 4 to 7 in FIG. 63, which have not been described, are for setting initial values at the start of EGR operation. Specifically, in step 4, the corrected actual EGR amount Qec Compare h with 0. Qec When h = 0 (that is, when EGR is not operating), the process proceeds to step 5,
[0184]
[Equation 24]
Qec h = Qac × MEGRL #
Where MEGRL #: constant,
From the equation, the corrected actual EGR amount Qec Set h. Similarly, in step 6, the actual EGR rate Megrd is compared with 0, and when Megrd = 0, in step 7
[0185]
(Equation 25)
Megrd = MEGRL #
The actual EGR rate Megrd is set by the following equation.
[0186]
The EGR flow rate passing through the EGR valve 6 when the EGR valve 6 is fully closed is, of course, zero. However, Equations 24 and 25 are parameters used for calculating the flow rate in consideration of the start of EGR operation. Set the initial value of. The value of MEGRL # is, for example, 0.5 as described above. More specifically, the differential pressure before and after the EGR valve (and therefore the EGR flow rate) at the start of the EGR operation differs depending on the operating conditions. In this case, the differential pressure across the EGR valve at the start of the EGR operation is related to the actual intake air amount Qac. Therefore, according to equation 24, Qec is proportional to Qac. By giving the initial value of h, the calculation accuracy of the EGR flow speed at the start of the EGR operation is improved.
[0187]
Here, the operation of the two embodiments will be described.
[0188]
The target intake air amount tQac is calculated according to the operating conditions (Ne, Qsol), and is calculated based on the target intake air amount tQac and the actual EGR amount Qec in the first embodiment, and is calculated in the second embodiment. Since the target opening ratio Rvnt, which is the operation target value of the supercharger, is set based on the amount tQac and the actual EGR rate Megrd, the target EGR amount (Qec0), which is the control target value of the EGR device, and the target EGR rate Even if Megr changes, a target intake air amount that optimizes fuel efficiency can be obtained, and the controllability of the turbocharger and the EGR device including transients is improved, and thereby the mutual performance is sufficiently exhibited. Can be done. It is also possible to simplify adaptation and logic.
[0189]
In particular, during transition, even if the target EGR amount and the target EGR rate Megr change stepwise, there is a delay before the actual EGR amount Qec and the actual EGR rate Megrd catch up with the target EGR amount and the target EGR rate Megr (the target EGR rate (See FIG. 65 and FIG. 66 for the Megr and the actual EGR rate Megrd), an error occurs in the target opening ratio Rvnt by a deviation from the target EGR amount and the target EGR rate Megr, and a target intake air amount that optimizes fuel efficiency cannot be obtained. Although there is a possibility, when setting the target opening ratio Rvnt, according to the first embodiment, the actual EGR amount Qec which is a value obtained by performing a delay process on the target EGR amount, and according to the second embodiment, the target EGR amount Since the actual EGR amount Megrd, which is a value obtained by performing a delay process on the rate Megr, is used, the target intake air amount that optimizes fuel efficiency even during a transient period Obtained as to control the turbocharger.
[0190]
Also, at the time of acceleration, the actual EGR rate Megrd becomes larger than the target EGR rate Megr (see FIGS. 65 and 66), and this shift causes smoke. On the other hand, according to the present embodiment, the actual common rail pressure is reduced. Since the target EGR rate is corrected to decrease at the time of acceleration lower than the target common rail pressure, generation of smoke at the time of acceleration can be prevented. Note that the target EGR rate Megr shown in FIGS. 65 and 66 is before the target EGR rate is corrected for reduction.
[0191]
In this case, in the case of a common rail type fuel injection device in which the common rail pressure becomes the fuel injection pressure, although the generation of smoke can be prevented by correcting the common rail pressure to the high pressure side for a certain period of time, the originally high common rail pressure is reduced. If the pressure is further corrected to the high pressure side during acceleration, the drive loss of the supply pump is increased, and the fuel loss is deteriorated due to the increase in the drive loss. However, according to the present embodiment, the common rail pressure is reduced by the operating conditions (Ne, Qsol). ) Is changed according to the map of FIG. 67, but is not corrected at the time of acceleration. Therefore, even if the common rail type fuel injection device is provided, the fuel consumption is deteriorated due to an increase in the drive loss of the supply pump and the common rail type fuel injection device A decrease in durability can be prevented.
[0192]
Further, according to the present embodiment, it is possible to cope with the fact that the amount (sensitivity) to be corrected differs depending on the engine load even for the same injection pressure error (common rail pressure error). For example, the rate at which the target EGR rate is corrected to decrease is changed according to the engine load (Qsol) corresponding to the load at the time of acceleration, and the rate at which the target EGR rate is corrected to decrease at the time of acceleration with a large load is set to be smaller than at the time of acceleration with a small load. By making the control value larger (that is, the control target value is made smaller at the time of acceleration with a large load than at the time of acceleration with a small load), generation of smoke can be prevented with good response even at the time of acceleration with a large load.
[0193]
In the embodiment, the case where the control target value of the EGR device is the target EGR rate has been described, but the target EGR amount may be set as the control target value of the EGR device.
[0194]
In the embodiment, the description has been given of the case where the means for controlling the fuel injection pressure to be the target injection pressure is a common rail type fuel injection device, but the present invention is not limited to this.
[0195]
In the embodiment, the target intake air amount tQac is calculated, and the target opening ratio Rvnt, which is the operation target value of the supercharger, is calculated based on this value, the actual EGR amount Qec, which is the actual control value of the EGR device, and the actual EGR rate Megrd. As described above, the target supercharging pressure may be used instead of the target intake air amount tQac.
[0196]
In the embodiment, the turbocharger in which the supercharging pressure changes according to the opening ratio of the variable nozzle has been described. However, the present invention is not limited to this, and may be applied to the following.
[0197]
(1) Another type of turbocharger in which the supercharging pressure changes according to the flow rate,
(2) Constant-capacity turbocharger with wastegate valve,
(3) Supercharger,
For example, for the turbocharging pressure of (1), the opening ratio and opening area of the flow rate variable means of the supercharger or the control ratio and the operating ratio given to the actuator for driving the supercharger are expressed in (2). For the turbocharger, the opening ratio and the opening area of the wastegate valve, and for the supercharger (3), the control ratio and the operation ratio given to the actuator for driving the supercharger are set as the operation target of the supercharger. It may be used as a value.
[0198]
In the embodiment, the case of performing so-called low-temperature premixed combustion in which the pattern of heat generation is single-stage combustion has been described. However, even in the case of normal diesel combustion in which diffusion combustion is added after premixed combustion, the present invention is also applicable. It goes without saying that the invention can be applied.
[Brief description of the drawings]
FIG. 1 is a control system diagram of an embodiment.
FIG. 2 is a schematic configuration diagram of a common rail type fuel injection device.
FIG. 3 is a flowchart for explaining calculation of a target fuel injection amount.
FIG. 4 is a map characteristic diagram of a basic fuel injection amount.
FIG. 5 is a flowchart for explaining the calculation of an EGR valve opening area.
FIG. 6 is a characteristic diagram of an EGR valve drive signal with respect to an EGR valve opening area.
FIG. 7 is a flowchart for explaining calculation of a target EGR amount.
FIG. 8 is a flowchart for explaining calculation of a cylinder intake air amount.
FIG. 9 is a flowchart for explaining detection of an intake air amount.
FIG. 10 is a characteristic diagram of an intake air amount with respect to an air flow meter output voltage.
FIG. 11 is a flowchart for explaining calculation of a target EGR rate.
FIG. 12 is a map characteristic diagram of a basic target EGR rate.
FIG. 13 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 14 is a flowchart for explaining complete explosion determination.
FIG. 15 is a flowchart for explaining calculation of a control command duty value given to the negative pressure control valve according to the first embodiment.
FIG. 16 is a flowchart for explaining calculation of a control command duty value given to a negative pressure control valve according to the second embodiment.
FIG. 17 is a flowchart for explaining calculation of an actual EGR rate.
FIG. 18 is a flowchart for explaining calculation of a time constant equivalent value for a collector capacitance.
FIG. 19 is a map characteristic diagram of a basic value corresponding to volume efficiency.
FIG. 20 is a flowchart for explaining calculation of a target intake air amount.
FIG. 21 is a map characteristic diagram of a target intake air amount basic value during EGR operation.
FIG. 22 is a map characteristic diagram of a target intake air amount correction coefficient.
FIG. 23 is a map characteristic diagram of a target intake air amount when EGR is not operated.
FIG. 24 is a flowchart for explaining calculation of an actual EGR amount.
FIG. 25 is a flowchart illustrating the calculation of a target opening ratio according to the first embodiment.
FIG. 26 is a map characteristic diagram of a target opening ratio.
FIG. 27 is a flowchart for explaining calculation of a target opening ratio according to the second embodiment.
FIG. 28 is a map characteristic diagram of a target opening ratio.
FIG. 29 is a flowchart for explaining the calculation of the feedforward amount of the target opening ratio.
FIG. 30 is a flowchart for explaining calculation of a feedback amount of a target opening ratio.
FIG. 31 is a flowchart for explaining linearization processing;
FIG. 32 is a table characteristic diagram of linearization.
FIG. 33 is a characteristic diagram showing a relationship between an opening area and a supercharging pressure.
FIG. 34 is a flowchart for explaining signal conversion.
FIG. 35 is a flowchart illustrating the setting of a duty selection signal flag.
FIG. 36 is a flowchart for explaining calculation of a temperature correction amount of a duty value.
FIG. 37 is a map characteristic diagram of a basic exhaust gas temperature.
FIG. 38 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 39 is a table characteristic diagram of a temperature correction amount.
FIG. 40 is a temperature characteristic diagram of a turbocharger driving actuator.
FIG. 41 is a map characteristic diagram of the duty value when the variable nozzle is fully closed.
FIG. 42 is a map characteristic diagram of the duty value when the variable nozzle is fully opened.
FIG. 43 is a map characteristic diagram of the duty value when the variable nozzle is fully closed.
FIG. 44 is a map characteristic diagram of the duty value when the variable nozzle is fully opened.
FIG. 45 is a hysteresis diagram when a command opening ratio linearization processing value is converted into a duty value.
FIG. 46 is a flowchart for explaining operation confirmation control;
FIG. 47 is a flowchart illustrating the setting of an operation check control command duty value.
FIG. 48 is a table characteristic diagram of a control pattern.
FIG. 49 is a table characteristic diagram of duty values during operation check control.
FIG. 50 is a flowchart for explaining the calculation of two feedback correction coefficients and a learning correction coefficient of EGR control.
FIG. 51 is a flowchart for explaining setting of a feedback permission flag.
FIG. 52 is a flowchart for describing setting of a learning value reflection permission flag.
FIG. 53 is a flowchart illustrating the setting of a learning permission flag.
FIG. 54 is a flowchart illustrating the calculation of an EGR amount feedback correction coefficient.
FIG. 55 is a map characteristic diagram of an EGR flow rate correction gain.
FIG. 56 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 57 is a flowchart for explaining the calculation of an EGR flow velocity feedback correction coefficient.
FIG. 58 is a map characteristic diagram of a correction gain of the EGR flow velocity.
FIG. 59 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 60 is a table showing a learning map of an error ratio learning value.
FIG. 61 is a flowchart illustrating updating of a learning value;
FIG. 62 is a map characteristic diagram of learning speed.
FIG. 63 is a flowchart for explaining the calculation of the EGR flow velocity.
FIG. 64 is a map characteristic diagram of an EGR flow velocity.
FIG. 65 is a waveform chart when the change in the target air amount is small.
FIG. 66 is a waveform chart in a case where a change in a target air amount is large.
FIG. 67 is a map characteristic diagram of a target common rail pressure.
FIG. 68 is a flowchart for explaining calculation of a common rail pressure correction ratio.
FIG. 69 is a table characteristic diagram of a common rail pressure error correction coefficient.
FIG. 70 is a diagram corresponding to the claim of the first invention.
FIG. 71 is a view corresponding to claims of the sixth invention.
4 EGR passage
6 EGR valve
10 Common rail fuel injection system
41 Control Unit
56 Negative pressure control valve

Claims (6)

An EGR device;
Means for calculating the control target value of the EGR device according to the load of the engine;
Means for calculating a target injection pressure according to the load of the engine;
Means for controlling the fuel injection pressure to be the target injection pressure;
Means for detecting the actual injection pressure;
Means for comparing the actual injection pressure with the target injection pressure;
Means for reducing and correcting the control target value when the actual injection pressure is lower than the target injection pressure from the comparison result;
Means for controlling the EGR device so as to obtain the corrected control target value. The control device for a diesel engine according to claim 1, wherein the target injection pressure is an injection pressure for a request in a steady state. The control device for a diesel engine according to claim 1, wherein the control target value is a target EGR rate or a target EGR amount. The diesel engine control device according to claim 1, further comprising a common rail fuel injection device, wherein the fuel injection pressure is a common rail pressure. The control device for a diesel engine according to claim 1, wherein a rate of decreasing and correcting the control target value is changed in accordance with an engine load. Including an EGR device and a supercharger,
Means for calculating a control target value of the EGR device according to an engine load;
Means for calculating a target intake air amount or a target supercharging pressure according to operating conditions;
Means for setting an operation target value of the supercharger based on the target intake air amount or the target supercharging pressure and a control target value of the EGR device;
Means for controlling the supercharger so as to be the operation target value of the supercharger,
Means for calculating a target injection pressure according to the load of the engine;
Means for controlling the fuel injection pressure to be the target injection pressure;
Means for detecting the actual injection pressure;
Means for comparing the actual injection pressure with the target injection pressure;
Means for correcting the control target value when the actual injection pressure is lower than the target injection pressure from the comparison result, and for not performing the correction correction for the control target value when the actual injection pressure matches the target injection pressure;
When the actual injection pressure is lower than the target injection pressure from the comparison result, the control target value is corrected so as to be the reduced correction target value. Means for controlling the EGR device so as to provide the following.

Images