JP3726669B2 - Supercharger control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a supercharger, and more particularly, to a device equipped with an EGR device (device for recirculating a part of exhaust gas to an intake passage) in addition to a variable supercharging pressure mechanism.
[0002]
[Prior art]
There is one that feedback-controls a command value given to an actuator for driving a supercharging pressure variable mechanism so that an actual supercharging pressure coincides with a target supercharging pressure (see JP-A-8-338256).
[0003]
[Problems to be solved by the invention]
By the way, since the target boost pressure has been increased with respect to the change in the operation region, when the actuator for driving the variable boost pressure mechanism is moved so as to obtain this increased target boost pressure, If a phenomenon occurs in which the actual value of the supply pressure increases beyond the supercharging limit (this phenomenon is hereinafter referred to as “overboost”) (see the one-dot chain line in the bottom of FIG. 108), noise and exhaust performance deteriorate. .
[0004]
Further, when the EGR device is operated during the supercharging pressure control as in the prior application device of Japanese Patent Application No. 11-233124 (hereinafter simply referred to as “prior application device”), the operating range of the EGR device is as follows. When the above overboost occurs, the intake pressure and the exhaust pressure fluctuate due to the instability of control on the turbocharger side that accompanies the overboost. As a result, the EGR amount fluctuates due to this influence, and the NOx emission amount thereby increases. It will also get worse.
[0005]
In order to avoid such overboost in the supercharging pressure control, when the change amount of the actual supercharging pressure becomes a predetermined value or more, or the change amount of the actual intake air amount (equivalent to the actual supercharging pressure) becomes a predetermined value or more. It is conceivable that an overboost will occur and the actuator for driving the variable supercharging pressure mechanism is moved to the side where the supercharging pressure decreases.
[0006]
However, in this method, when the EGR device is operated during the supercharging pressure control, an erroneous determination that an overboost has occurred may occur.
[0007]
This will be specifically described based on the amount of change in the actual intake air amount. When the actuator is moved to the side where the variable nozzle (supercharging pressure variable mechanism) is closed (the side where the supercharging pressure rises) in FIG. The actual intake air amount Qac is 500 mg / st. cyl to the supercharging limit of 650 mg / st. cyl over 700 mg / st. When changing to cyl. In this case, the change amount ΔQac of the actual intake air amount from the timing t2 is 100 mg / st. If there is cyl, it can be determined that overboost occurs at this time.
[0008]
On the other hand, in the lower part of FIG. 113, although the variable nozzle does not move, the EGR valve opening decreases due to the operation of the EGR device, so that the exhaust pressure rises. As a result, the supercharging work increases, and the actual intake air amount Qac becomes 200 mg / st. cyl to 500 mg / st. When rising to cyl. In this case, the change amount ΔQac of the actual intake air amount from the timing t4 is 100 mg / st. Even if there is cyl, overboost does not occur. However, in the method for determining whether or not overboost occurs based only on the change amount ΔQac of the actual intake air amount, the upper case and the lower case in FIG. 113 cannot be separated. It will be misjudged.
[0009]
Therefore, the present invention is a type that adopts not only the actual intake air amount but also the actual EGR amount in the case of adopting the intake air amount corresponding to the supercharging pressure, and also adopts the supercharging pressure itself. In this case, by determining whether or not overboost occurs based on the actual boost pressure in the operating range of the EGR device, erroneous determination of overboost accompanying the operation of the EGR device during the boost pressure control is prevented. For the purpose.
[0010]
Next, FIG. 110 shows a variable nozzle opening ratio (a value corresponding to an opening area) in one engine when the type adopts the intake air amount, and FIG. 111 shows the type adopting the supercharging pressure itself. As will be described later), the results of steady-state experiments with various changes in engine speed and engine load are summarized into one. 110, the actual intake air amount Qac and the actual EGR are the same due to the difference in operating conditions (engine load, engine speed) or the difference in the opening ratio even if the operating conditions are the same. It can be seen that the total value of the amount Qec and the actual exhaust amount Qexh vary considerably, and in FIG. 111, the actual boost pressure and the actual exhaust amount Qexh vary considerably. This variation is due to manufacturing variations such as the means for detecting the intake air amount and the actuator for driving the variable supercharging pressure in the case of a type that uses the intake air amount, and in the case of a type that uses the supercharging pressure itself. This is due to manufacturing variations of the means for detecting the supercharging pressure and the actuator for driving the supercharging pressure variable mechanism. Plots exceeding the indicated supercharging limit due to such variations in Qac + Qec and Qexh in the case of the type adopting the intake air amount, and variations in the actual supercharging pressure and Qexh in the type employing the supercharging pressure itself. Over-boost will occur under certain conditions.
[0011]
Therefore, the present invention is based on the actual exhaust air amount in addition to the actual intake air amount and the actual EGR amount in the case of the type employing the intake air amount, and in the case of the type employing the supercharging pressure itself. In addition to this, by determining whether or not overboost occurs based on the actual displacement, it is possible to reduce the total value of the actual intake air amount and the actual EGR amount and the variation of the actual exhaust amount in the case of the type adopting the intake air amount. In addition, an object of the present invention is to prevent overboost associated with variations in the actual boost pressure and the actual displacement in the case of a type that uses the boost pressure itself.
[0012]
[Means for Solving the Problems]
  In the first invention, as shown in FIG. 114, a turbocharger 61 having an actuator 62 for driving a supercharging pressure variable mechanism, and a target intake air amount or a target supercharging pressure are set according to operating conditions. Means 63, means 64 for controlling the actuator 62 so as to obtain the target intake air amount or the target supercharging pressure, an EGR device 65, means 66 for detecting the actual intake air amount, and the EGR The actual EGR amount of the device 65CalculationMeans 67 for determining whether overboost occurs based on the actual intake air amount and the actual EGR amount, and means for suppressing the boost pressure so that overboost does not occur based on the determination result 69.
[0013]
  In the second invention, as shown in FIG. 115, a turbocharger 61 having an actuator 62 for driving a supercharging pressure variable mechanism, and a target intake air amount or a target supercharging pressure are set according to operating conditions. Means 63, means 64 for controlling the actuator 62 so as to obtain the target intake air amount or the target supercharging pressure, an EGR device 65, means 66 for detecting the actual intake air amount, and the EGR The actual EGR amount of the device 65CalculationMeans 67 for calculating the actual exhaust amount, means 72 for determining whether overboost occurs based on the actual intake air amount, the actual EGR amount, and the actual exhaust amount, and based on the determination result Means 69 for suppressing the boost pressure is provided so as not to cause overboost.
[0014]
In the third invention, the means 72 for determining whether or not overboost occurs in the second invention, the means for calculating the sum of the actual EGR amount and the actual intake air amount as the cylinder intake gas amount Qcyl, and the actual exhaust amount Qexh And a means for setting the determination value TQcyl according to the above, and when the cylinder intake gas amount Qcyl is equal to or larger than the determination value TQcyl, it is determined that overboost does not occur when the cylinder intake gas amount Qcyl is less than the determination value TQcyl. It consists of means to do.
[0016]
  First4The invention116As shown in FIG. 4, a turbocharger 61 having an actuator 62 for driving a supercharging pressure variable mechanism, means 63 for setting a target intake air amount or a target supercharging pressure according to operating conditions, and this target intake A means 64 for controlling the actuator 62 so as to obtain an air amount or a target supercharging pressure, an EGR device 65, a means 71 for calculating an actual exhaust amount, and an actual excess in the operating range of the EGR device 65. A means 81 for detecting the supply pressure, a means 91 for determining whether or not overboost occurs based on the actual boost pressure and the actual exhaust amount, and a boost pressure so that no overboost occurs based on the determination result Means 69 for suppressing the above are provided.
[0017]
  First5In the invention of the4In the present invention, the means 91 for determining whether or not overboost occurs is a means for setting the determination value TPa according to the actual displacement Qexh, and when overboost occurs when the actual boost pressure is equal to or greater than the determination value TPa, And means for determining that overboost does not occur when the actual boost pressure is less than the determination value TPa.
[0018]
  First6In the invention of the first to first5In any one of the above-described inventions, the means 64 for controlling the actuator 62 is excessive based on the target intake air amount or the target boost pressure and the control target value of the EGR device 65 (for example, the target EGR rate or the target EGR amount). The target operating value of the charger 61 (for example, a type that can variably adjust the geometric shape of the exhaust turbine, for example, a target value of the opening area of the supercharger 61 or an equivalent value of the opening area, The means 69 for controlling the supercharging pressure when the means for setting the target value) and the means for controlling the actuator 62 so as to become the operation target value of the supercharger 61 are the supercharger. The setting value of the means for setting the operation target value of 61 is set on the side where the boost pressure is weakened compared to the condition where overboost does not occur when the overboost occurs. It is a means to switch to.
[0019]
  First7In the invention of the first to first6In any one of the above-described inventions, the period (for example, time) TTMROB0 in which the boost pressure is suppressed so as not to cause overboost is set as the change amount DQSOL per predetermined time of the engine load (for example, target fuel injection amount Qsol) or engine rotation The speed NE is set according to the change amount DNE per predetermined time.
[0020]
  First8In the invention of any one of the first to third inventions, the period (for example, time) TTMROB0 in which the boost pressure is suppressed so as not to cause overboost is set to the change amount of the actual intake air amount Qac per predetermined time. Set according to DQAC.
[0021]
  First9In the invention of the third aspect, the period (for example, time) TTMROB0 in which the boost pressure is suppressed so as not to cause overboost in the third invention is set in accordance with the deviation amount of the cylinder intake gas amount Qcyl from the determination value TQcyl or the exhaust amount. Set.
[0022]
  First10In the invention of the first to first9In any one of the inventions described above, when the supercharging pressure is suppressed and then the actuator is returned to the side where the supercharging pressure rises, the movement of the actuator is delayed.
[0023]
  First11In the invention of the10In this invention, the period for delaying the movement of the actuator is set according to the atmospheric pressure or the displacement.
[0024]
  First12According to the invention, in the third invention, the determination value TQcyl is set with a characteristic that is substantially mountain-shaped with respect to the displacement.
[0025]
【The invention's effect】
  In order to avoid overboost in the boost pressure control, when the intake air volume changes, the actual intake air volume changes more than the specified value, or when the boost pressure itself is used. When the amount of change in the actual boost pressure exceeds the specified value, it is determined that overboost occurs, and the actuator for driving the boost pressure variable mechanism is moved to the side where the boost pressure decreases. When the EGR device is operated during the supply pressure control, an erroneous determination that overboost occurs may occur. However, in the case of a type that employs an intake air amount,6According to the invention, in the case of a type that adopts not only the actual intake air amount but also the actual EGR amount and also adopts the supercharging pressure itself.6thAccording to the invention, since it is determined whether or not overboost occurs based on the actual boost pressure in the operating range of the EGR device, an erroneous determination of overboost accompanying the operation of the EGR device during the boost pressure control is made. Can be prevented.
[0026]
  In the case of a type that uses the intake air amount, the second, third, and second6According to the invention, since it is determined whether or not overboost has occurred based on the actual exhaust air amount and the actual exhaust gas amount in addition to the actual intake air amount, the intake air amount is employed in addition to the effects of the first invention. In the case of the type, it is possible to prevent overboost caused by manufacturing variations such as a means for detecting the intake air amount and an actuator for driving the supercharging pressure variable mechanism.
[0027]
  In the case of a type that uses the supercharging pressure itself,4The second5The second6According to the present invention, it is determined whether or not overboost has occurred based on the actual displacement in addition to the actual boost pressure in the operating range of the EGR device.OverIn the case of a type that employs the supply pressure itself, it is possible to prevent overboost caused by manufacturing variations such as a means for detecting the supercharging pressure and an actuator for driving the variable supercharging pressure mechanism.
[0028]
  Over-boost is more likely to occur as the engine load, engine speed, and actual intake air amount change more, or as the amount of deviation from the cylinder intake gas amount judgment value or the exhaust amount increases. Therefore, when the amount of change in these three factors (engine load, engine speed, actual intake air amount) is small, or when the deviation from the judgment value of the cylinder intake gas amount or the exhaust amount is small If the amount of change between these three is large or the amount of deviation from the judgment value of the cylinder intake gas amount or the exhaust amount is large, the period for suppressing the boost pressure is too short, and over boost occurs, On the contrary, if the amount of change between these three factors is large, or if the amount of deviation from the judgment value of the cylinder intake gas amount or the exhaust amount is large, the period for suppressing the supercharging pressure is matched, If it is small or the deviation from the judgment value of the cylinder intake gas amount or the exhaust amount is small, the period for suppressing the supercharging pressure is too long, and unnecessary supercharging pressure is suppressed.7The second8The second9According to the invention, the time for suppressing the boost pressure is increased as the amount of change in any one of the engine load, the engine speed, the actual intake air amount, the deviation from the determination value of the cylinder intake gas amount, or the exhaust amount is larger. By making it longer, you can avoid this situation.
[0029]
  If the actuator is quickly moved to the side where the boost pressure rises in order to return to the state before suppressing the boost pressure after suppressing the boost pressure, it may cause overboost due to that. First10According to this invention, such a situation can be avoided.
[0030]
  Since the displacement increases with the differential pressure between the exhaust pressure and the atmospheric pressure, the displacement increases under conditions of low atmospheric pressure such as high altitudes, and the work performed by the turbocharger increases accordingly (overboost) Is more likely to occur). Therefore, if you match the period of delaying the actuator's movement to a condition where the atmospheric pressure is not low such as lowland, the period of delaying the actuator's movement under the condition of lower atmospheric pressure is too short, causing overboost, On the other hand, if the period of delaying the actuator movement is matched against conditions with low atmospheric pressure such as the high altitude, the period of delaying the actuator movement in the low altitude is unnecessarily long. Set the period for delaying according to the atmospheric pressure.11According to the invention, such a situation can be avoided.
[0031]
  Over-boost is likely to occur when the displacement exceeds a predetermined value, so if you match the period in which the actuator movement is delayed under the condition that the displacement does not exceed the predetermined value, the actuator Over-boost occurs when the period of delaying the movement is too short, and conversely, if the period of delaying the movement of the actuator is matched under the condition that the displacement exceeds the predetermined value, the movement of the actuator is controlled under the condition that the displacement does not exceed the predetermined value. The delay period becomes unnecessarily long, but the period for delaying the actuator movement is set according to the displacement.11According to the invention, such a situation can be avoided.
[0032]
  First12According to this invention, the efficiency (fresh air amount) increases as the displacement increases from a small value, and the efficiency can be set according to the characteristics of the turbocharger where the efficiency decreases as the displacement increases. .
[0033]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration for performing so-called low-temperature premixed combustion in which the heat generation pattern is single-stage combustion. This configuration itself is known from JP-A-8-86251.
[0034]
Now, the generation of NOx greatly depends on the combustion temperature, and lowering the combustion temperature is effective for reducing it. In low-temperature premixed combustion, in order to realize low-temperature combustion by reducing the oxygen concentration by EGR, the EGR passage 4 connecting the exhaust passage 2 and the collector portion 3a of the intake passage 3 is responsive to the control pressure from the pressure control valve 5. A diaphragm type EGR valve 6 is provided.
[0035]
The pressure control valve 5 is driven by a duty control signal from the control unit 41, and thereby obtains a predetermined EGR rate corresponding to operating conditions. For example, the EGR rate is set to a maximum of 100 percent in a low rotation and low load region, and the EGR rate is decreased as the rotation speed and load increase. Since the exhaust gas temperature rises on the high load side, if a large amount of EGR gas is recirculated, the effect of NOx reduction is reduced due to the rise of the intake air temperature, or the ignition delay period of the injected fuel is shortened and premix combustion cannot be realized. For this reason, the EGR rate is gradually reduced.
[0036]
An EGR gas cooling device 7 is provided in the middle of the EGR passage 4. This is because of a water jacket 8 formed around the EGR passage 4 in which a part of the engine cooling water is circulated, and a flow rate control valve 9 provided at the cooling water inlet 7a and capable of adjusting the circulation amount of the cooling water. Thus, the degree of cooling of the EGR gas increases as the amount of circulation increases through the control valve 9 according to a command from the control unit 41.
[0037]
A swirl control valve (not shown) having a predetermined notch is provided in the intake passage near the intake port to promote combustion. When the swirl control valve is closed by the control unit 41 in the low rotation and low load range, the flow rate of the intake air sucked into the combustion chamber is increased and swirl is generated in the combustion chamber.
[0038]
The combustion chamber is a large-diameter toroidal combustion chamber (not shown). This is because the piston cavity is formed in a cylindrical shape from the crown to the bottom of the piston without restricting the inlet, and at the center of the bottom, resistance is given to the swirl that swirls from the outside of the piston cavity in the latter half of the compression stroke. In order to further improve the mixing of air and fuel, a conical portion is formed. Due to the cylindrical piston cavity that does not restrict the inlet, the swirl generated by the swirl valve or the like is diffused from the inside of the piston cavity to the outside of the cavity as the piston descends during the combustion process. The swirl is sustained.
[0039]
The engine includes a common rail fuel injection device 10. The configuration of the common rail type fuel injection device 10 is also known (see the 13th internal combustion engine symposium symposium, pages 73-77) and is outlined with reference to FIG.
[0040]
The fuel injection device 10 mainly includes a fuel tank 11, a fuel supply passage 12, a supply pump 14, a common rail (accumulation chamber) 16, and a nozzle 17 provided for each cylinder. The fuel pressurized by the supply pump 14 is fuel. After being stored once in the pressure accumulation chamber 16 via the supply passage 15, the high pressure fuel in the pressure accumulation chamber 16 is distributed to the nozzles 17 corresponding to the number of cylinders.
[0041]
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 that urges the needle valve 18 in the valve closing direction (downward in the figure), hydraulic pressure It comprises a fuel supply passage 24 to the piston 22 and a three-way valve (solenoid valve) 25 interposed in the passage 24. The passages 20 and 24 in the nozzle communicate with each other so that both the upper part of the hydraulic piston 22 and the nozzle chamber 19 have a high pressure. Since the pressure receiving area of the hydraulic piston 22 is larger than the pressure receiving area of the needle valve 18 when the three-way valve 25 to which the fuel is guided is OFF (ports A and B are connected and ports B and C are shut off), the needle valve 18 is While in the seating state, when the three-way valve 25 is in the ON state (ports A and B are shut off and 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 nozzle hole at the tip of the nozzle. When the three-way valve 25 is returned to the OFF state again, the high pressure fuel in the pressure accumulating chamber 16 is guided to the hydraulic piston 22 and the fuel injection is completed. That is, if the three-way valve 25 is switched from OFF to ON, the fuel injection start time is adjusted by the ON time, and the fuel injection amount is adjusted by the ON time. The amount increases. 26 is a check valve and 27 is an orifice.
[0042]
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 pressure in the pressure accumulation chamber. The adjustment valve 31 opens and closes the flow path of the passage 13 and adjusts the pressure in the pressure accumulation chamber by adjusting the amount of fuel discharged to the pressure accumulation chamber 16. The fuel injection rate varies depending on the fuel pressure (injection pressure) in the pressure accumulating chamber 16, and the fuel injection rate increases as the fuel pressure in the pressure accumulating chamber 16 increases.
[0043]
An accelerator opening sensor 33, a sensor 34 for detecting the engine speed and crank angle, a sensor 35 for cylinder discrimination, and a control unit 41 to which signals from the water temperature sensor 36 are input correspond to the engine speed and the accelerator opening. The target fuel injection amount and the target pressure of the pressure accumulating chamber 16 are calculated, and the fuel pressure in the pressure accumulating chamber 16 is fed back via the pressure regulating valve 31 so that the pressure accumulating chamber pressure detected by the pressure sensor 32 matches the target pressure. Control.
[0044]
In addition to controlling the ON time of the three-way valve 25 corresponding to the calculated target fuel injection amount, by controlling the switching time of the three-way valve 25 to ON, a predetermined injection start time corresponding to the operating condition is obtained. I am doing so. For example, the fuel injection timing (injection start timing) is delayed to the piston top dead center (TDC) so that the ignition delay period of the injected fuel becomes longer on the low rotation and low load side with a high EGR rate. By this delay, the temperature in the combustion chamber at the ignition timing is lowered, and the premixed combustion ratio is increased, thereby suppressing the occurrence of smoke in the high EGR rate region. On the other hand, the injection timing is advanced as the rotational speed and load increase. This is because, even if the ignition delay time is constant, the ignition delay crank angle (the value obtained by converting the ignition delay time into a crank angle) increases in proportion to the increase in the engine speed, and a predetermined value is obtained at a low EGR rate. The injection timing is advanced in order to obtain the ignition timing.
[0045]
Returning to FIG. 1, a variable capacity turbocharger is provided in the exhaust passage 2 downstream of the opening of the EGR passage 4. This is a variable nozzle 53 driven by an 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 degree (tilting state) for increasing the flow rate of the exhaust gas introduced into the exhaust turbine 52 is controlled, and on the high rotation side, exhaust gas is introduced into the exhaust turbine 52 without resistance and controlled to the nozzle opening degree (fully open state).
[0046]
The actuator 54 includes a diaphragm actuator 55 that drives the variable nozzle 53 in response to the control pressure, and a pressure control valve 56 that adjusts the control pressure to the diaphragm actuator 55. The opening ratio of the variable nozzle 53 is as follows. A duty control signal is generated so as to obtain a target opening ratio Rvnt obtained as described later, and this duty control signal is output to the pressure control valve 56.
[0047]
From the viewpoint of supercharging pressure control, EGR control also physically plays the role of supercharging pressure control. That is, the supercharging pressure also changes by changing the EGR amount. On the contrary, if the supercharging pressure is changed, the exhaust pressure changes, so the EGR amount also changes, and the supercharging pressure and the EGR amount cannot be controlled independently. In addition, there is a disturbance in control of each other. In order to ensure control accuracy when one is changed, it is necessary to re-adjust the other. However, after re-adapting the other, the other must be re-adapted. In the method, it is difficult to ensure the control accuracy at the time of transition.
[0048]
As described above, the supercharging pressure and the EGR amount affect each other. If the EGR amount is changed, it is difficult to properly adjust the nozzle opening degree. Therefore, in the control unit 41, the target intake air amount tQac is calculated 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. A target opening ratio Rvnt of the variable nozzle 53, which is an operation target value of the turbocharger, is set from the amount Qec and the actual EGR rate Megrd.
[0049]
Further, feedback control is performed so that the actual intake air amount matches the target value. At this time, a value obtained by performing a delay process corresponding to the delay of the intake system with respect to the target intake air amount tQac set according to the operating conditions (rotation speed, load) is set as a target value in the feedback control.
[0050]
Also, depending on the manufacturing variation of the air flow meter 39 and the actuator 54 and the usage environment (for example, atmospheric pressure) of the vehicle, the supercharging limit may be exceeded. To cope with this, the actual intake air amount and the actual EGR Judgment is made on the basis of the total amount of exhaust gas and the actual displacement, and if it exceeds the supercharging limit, the actuator is set to reduce the supercharging pressure for a predetermined period to suppress overboost. Move 54.
[0051]
Also, because overboost suppression is terminated and returned to normal operation, if the actuator 54 is suddenly moved to the side where the boost pressure is increased, overboost tends to occur again, so overboost suppression is terminated. Thus, when returning during normal operation, the actuator 54 is slowly returned.
[0052]
In this case, since the optimum value of time for suppressing overboost changes depending on the degree of acceleration, this is set according to the degree of transient. Moreover, since the optimum value of the time required to cancel the overboost and shift to the normal operation changes depending on the use environment and the exhaust amount, it is set according to the atmospheric pressure and the exhaust amount.
[0053]
The contents of this control executed by the control unit 41 will be described according to the following flowchart. 3 to 40, 54 (steps 1 to 3 only), FIG. 59 (steps 1 and 2 only), FIG. 62, and FIGS. 87 to 102 to be described later have already been proposed in the prior application device. It is the same.
[0054]
First, FIG. 3 is for calculating the target fuel injection amount Qsol, and inputs a REF signal (crank angle reference position signal, every 180 degrees for a 4-cylinder engine and every 120 degrees for a 6-cylinder engine). Run every time.
[0055]
In steps 1 and 2, the engine rotational speed Ne and the accelerator opening degree Cl are read. In step 3, the basic fuel injection amount Mqdrv is calculated by searching a map having the contents shown in FIG. 4 based on these Ne and Cl. In step 4, the basic fuel injection amount Mqdrv is corrected to be increased by the engine coolant temperature or the like, and the corrected value is set as the target fuel injection amount Qsol.
[0056]
FIG. 5 is for calculating the opening area Aev of the EGR valve 6 and is executed for each input of the REF signal.
[0057]
FIG. 5 is a main routine, and a large flow of control follows the steps shown in the figure, and subroutines are prepared for the processing of each step. Therefore, the following description will focus on subroutines.
[0058]
FIG. 7 (subroutine of step 1 in FIG. 5) is for calculating the target EGR amount Tqec per cylinder, and is executed every time the REF signal is input.
[0059]
In steps 1 and 2, the intake air amount Qacn per cylinder and the target EGR rate Megr are calculated.
[0060]
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.
[0061]
First, in FIG. 8, in step 1, the engine rotational speed Ne is read, and from this engine rotational speed Ne and the intake air amount Qas0 obtained from the air flow meter.
[0062]
[Expression 1]
Qac0 = (Qas0 / Ne) × KCON #,
Where KCON # is a constant,
The intake air amount Qac0 per cylinder is calculated by the following equation.
[0063]
The air flow meter 39 (see FIG. 1) is provided in the intake passage 3 upstream of the compressor, and performs delay processing for the transport delay from the air flow meter 39 to the collector portion 3a. The value of Qac0 before the integer constant) is obtained as the intake air amount Qacn per cylinder at the collector inlet 3a position. And in Step 4, for this Qacn
[0064]
[Expression 2]
Qac = Qac_n-1× (1-KIN × KVOL) + Qacn × KIN × KVOL,
Where KIN: volumetric efficiency equivalent value,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
Qac_n-1: Last Qac,
Qac is calculated by the following equation (first-order lag equation) at the intake valve position per cylinder (this intake air amount is hereinafter abbreviated as “cylinder intake air amount”). This is to compensate for the dynamics from the collector inlet 3a to the intake valve.
[0065]
The detection of the intake air amount Qas0 on the right side of Equation 1 will be described with reference to the flowchart of FIG. The flow in FIG. 9 is executed every 4 ms.
[0066]
In step 1, the output voltage Us of the air flow meter 39 is read, and in step 2, a voltage-flow rate conversion table having the contents shown in FIG. d is calculated. 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.
[0067]
Next, in FIG. 11, in step 1, the engine speed Ne, the target fuel injection amount Qsol, and the engine coolant temperature Tw are read. In step 2, the basic target EGR rate Megarb 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 becomes larger as the engine is used more frequently, that is, at a low turning point and a low load (low injection amount), and is reduced at a high output at which smoke is likely to occur.
[0068]
Next, in step 3, the water temperature correction coefficient Kegr for the basic target EGR rate is retrieved by searching a table having the contents shown in FIG. 13 from the cooling water temperature Tw. tw is calculated. In step 4, from the basic target EGR rate and the water temperature correction coefficient,
[0069]
[Equation 3]
Megr = Megrb × Kegr tw
The target EGR rate Megr is calculated by the following formula.
[0070]
In step 5, it is determined whether or not the engine is in a complete explosion state. However, the determination of complete explosion will be described later with reference to the flowchart of FIG.
[0071]
In step 6, it is determined whether or not a complete explosion has occurred. If it is a complete explosion, the current process is terminated as it is. If it is determined that the explosion is not complete, the target EGR rate Megr is set to 0 and the current process is terminated.
[0072]
Thereby, 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.
[0073]
FIG. 14 is used to determine the complete explosion of the engine. In step 1, the engine rotation speed Ne is read, and the engine rotation speed Ne is compared with the complete explosion determination slice level NRPMK corresponding to the complete explosion rotation speed in step 2. When 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 the predetermined time TMRKBP, and when the counter Tmrkb is larger than the predetermined time, the process proceeds to step 4 and the process is terminated as it is completely exploded.
[0074]
On the other hand, when Ne is smaller in step 2, the process proceeds to step 6, the counter Tmrkb is cleared, and the process is terminated in step 7 assuming that the complete explosion state is not reached. 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.
[0075]
Thus, it is determined that the explosion has been completed 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.
[0076]
When the calculation of the cylinder intake air amount Qacn in FIG. 8 and the target EGR rate Megr in FIG. 11 are completed in this way, the process returns to step 3 in FIG.
[0077]
[Expression 4]
Mqec = Qacn × Megr
The required EGR amount Mqec is calculated by the following equation.
[0078]
In step 4, KIN × KVOL is used as a weighted average coefficient for this Mqec.
[0079]
[Equation 5]
Rqec = Mqec × KIN × KVOL + Rqec_n-1× (1-KIN × KVOL),
Where KIN: volumetric efficiency equivalent value,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
Rqec_n-1: Last intermediate processing value,
The intermediate processing value (weighted average value) Rqec is calculated by the following equation, and in step 5 using this Rqec and the required EGR amount Mqec
[0080]
[Formula 6]
Tqec = Mqec × GKQEC + Rqec_n-1× (1-GKQEC),
However, GKQEC: Lead correction gain,
The target EGR amount Tqec per cylinder is calculated by performing advance correction according to the following equation. Since there is a delay in the intake system with respect to the required value (that is, a delay corresponding to the capacity of the EGR valve 6 → the collector portion 3a → the intake manifold → the intake valve), Steps 4 and 5 perform advance processing for this delay. .
[0081]
Next, FIG. 15 and FIG. 16 are for calculating the target intake air amount tQac and are executed at regular intervals (for example, every 10 ms).
[0082]
When FIG. 15 is the first embodiment and FIG. 16 is the second embodiment, there are differences in parameters used to calculate the target opening ratio Rvnt of the variable nozzle 53 in the two embodiments (actual EGR in the first embodiment). Based on the amount Qec, and in the second embodiment, the target opening ratio Rvnt of the variable nozzle 53 is calculated based on the actual EGR rate Megrd).
[0083]
15 and 16 are also main routines, and subroutines are prepared for the processing of each step.
[0084]
FIG. 17 (subroutine of step 1 in FIGS. 15 and 16) is for calculating the actual EGR rate, and is executed every 10 ms. In step 1, the target EGR rate Megr (obtained in FIG. 11) is read, and in step 2, a time constant equivalent value Kkin corresponding to the collector capacity is calculated. The calculation of Kkin will be described with reference to the flowchart of FIG.
[0085]
In FIG. 18 (subroutine of step 2 of FIG. 17), in step 1, the engine rotation speed Ne, the target fuel injection amount Qsol, and the previous value of the actual EGR rate described later, Megrd_n-1[%] Is read, and a volume efficiency equivalent basic value Kinb is calculated by searching a map having the contents shown in FIG. 19 in step 2 from Ne and Qsol.
[0086]
[Expression 7]
Kin = Kinb × 1 / (1 + Megrd_n-1/ 100)
The volume efficiency equivalent value Kin is calculated by the following formula. This is because the volumetric efficiency is reduced by EGR, so that correction is made accordingly.
[0087]
The value obtained by multiplying Kin thus obtained by KVOL (see Step 4 in FIG. 8) corresponding to the ratio of the intake system volume to the cylinder volume in Step 4 is set as a time constant equivalent value Kkin for the collector capacity. Calculate.
[0088]
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,
[0089]
[Equation 8]
Megrd = Megr × Kkin × Ne × KE2 # + Megrd_n-1X (1-Kkin x Ne x 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 delay processing and unit conversion (per cylinder → per unit time) using the following equation. Ne × KE2 # on the right side of Equation 8 is a value for unit conversion. Since this Megrd responds to the target EGR rate Megr with a first-order lag, this Megrd is hereinafter referred to as “actual EGR rate”.
[0090]
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 MEGLV #.
[0091]
Here, the predetermined value MEGLV # is a value (for example, 0.5) for determining whether or not the EGR is operated. When Megrd> MEGRLV #, it is determined that the EGR is in the operation range, and steps 3, 4 and On the other hand, if Megrd ≦ MEGRLV #, on the other hand, it is determined that the EGR is in the non-operating range, and the process proceeds to step 6. MEGLV # is not 0 in response to a request for handling the same amount of EGR when it is not performed as when EGR is not performed.
[0092]
When it is within the EGR operating range, in step 3, the target intake air amount basic value tQacb is calculated by searching, for example, a map having the contents shown in FIG. 21 from the engine speed Ne and the actual EGR rate Megard. If the engine speed is constant, the target intake air amount is increased as the actual EGR rate is larger as shown in FIG.
[0093]
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 target coefficient by the target intake air amount basic value is calculated. Calculated as the target intake air amount tQac. The correction coefficient ktQac is for responding to a request for changing the target intake air amount according to the operating conditions (Ne, Qsol).
[0094]
On the other hand, when it is in the non-operating region of EGR, the process proceeds to step 6 and the target intake air amount tQac is calculated by searching a map having the contents shown in FIG. 23 from Ne and Qsol.
[0095]
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 at the collector inlet 3a position (obtained in step 3 of FIG. 8), the target EGR rate Megr, and the time constant equivalent value Kkin for the collector capacity are read. Of these, from Qacn and Megr
[0096]
[Equation 9]
Qec0 = Qacn × Megr
The EGR amount Qec0 per cylinder at the collector inlet 3a position is calculated by the following equation, and in step 3, using this Qec0 and Kkin,
[0097]
[Expression 10]
Qec = Qec0 × Kkin × Ne × KE # + Qec_n-1X (1-Kkin x Ne x KE #),
However, Kkin: Kin × KVOL,
KE #: constant,
Qec_n-1: Last Qec,
In the same manner as in the above equation 8, delay processing and unit conversion (per cylinder → per unit time) are performed simultaneously to calculate the cylinder intake EGR amount Qec. Ne × KE # on the right side of Equation 10 is a value for unit conversion. Since this Qec responds to the target EGR amount Tqek (described later in FIG. 40) with a first-order lag, this Qec is hereinafter referred to as “actual EGR amount”. The above Qac that responds to the target intake air amount tQac with a first-order delay is hereinafter referred to as “actual intake air amount”.
[0098]
FIG. 25 (subroutine of step 2 in FIG. 5) includes two calculations used for calculating the EGR amount and calculating the flow rate of EGR gas (the gas flowing through the EGR valve) (this EGR gas flow rate is hereinafter simply referred to as “EGR flow rate”). This is for calculating the feedback correction coefficients Kqac00 and Kqac0 and the EGR flow rate learning correction coefficient Kqac, and is executed every time the REF signal is input.
[0099]
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.
[0100]
In step 2, from the target intake air amount tQac
[0101]
## EQU11 ##
tQacd = tQac × KIN × KVOL × KQA # + tQacd_n-1× (1-KIN × KVOL × KQA #),
Where KIN: volumetric efficiency equivalent value,
KVOL: VE / NC / VM,
VE: displacement,
NC: number of cylinders
VM: intake system volume,
KQA #: constant,
tQacd_n-1: Last Qacd,
The target intake air amount delay processing value tQacd is calculated by the following equation (primary delay equation). In this case, delay processing is performed so that two feedback correction coefficients Kqac00, Kqac0 and a learning value Rqac, which will be described later, do not increase due to a delay in air supply due to the presence of the intake system volume.
[0102]
In step 3, various feedback-related flags are read. These settings will be described with reference to the flowcharts of FIGS. 26, 27, and 28.
[0103]
26, 27, and 28 are executed at regular intervals (for example, every 10 ms) independently of FIG.
[0104]
FIG. 26 is for setting the feedback permission flag fefb. In step 1, the engine rotational speed Ne, the target fuel injection amount Qsol, the actual EGR rate Megrd, and the water temperature Tw are read.
[0105]
The feedback permission condition is determined by checking the contents of Steps 2 to 5 and 8 one by one. When all the items are satisfied, the feedback is permitted. . That is,
Step 2: Megrd exceeds a predetermined value MEGRFB # (that is, EGR operating range),
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 exceeds a predetermined value NEFBL # (not in the rotational speed range that becomes the engine stall),
Step 8: The feedback start counter Ctrfb exceeds a predetermined value TMRFB # (for example, a value less than 1 second)
At step 9, the feedback permission flag fefb = 1 is set to permit feedback in step 9, otherwise, the process proceeds to step 10, and the feedback permission flag fefb = 0 is set to prohibit feedback.
[0106]
The feedback start counter is incremented when Steps 2 to 5 are established (Step 6), and is reset when Steps 2 to 5 are not established (Step 7).
[0107]
FIG. 27 is for setting the learned value reflection permission flag FERN2. In step 1, the engine rotational speed Ne, the target fuel injection amount Qsol, the actual EGR rate Megrd, and the water temperature Tw are read.
[0108]
The learning value reflection permission condition is also determined by checking the contents of Steps 2 to 5 and 8 one by one, and when all the items are satisfied, the learning value is permitted to be reflected, and even if one is contrary Prohibits the reflection of learning values. That is,
Step 2: Megrd exceeds a predetermined value MEGRLN2 # (that is, EGR operating range),
Step 3: Tw exceeds a predetermined value TWLNL2 # (for example, about 20 ° C.),
Step 4: Qsol exceeds a predetermined value QSOLNL2 # (no fuel cut),
Step 5: Ne exceeds a predetermined value NELNL2 # (not in the rotational speed range that becomes the engine stall),
Step 8: The learning value reflection counter Ctrlln2 exceeds a predetermined value TMRLN2 # (for example, about 0.5 seconds)
In step 9, the learning value reflection permission flag fel2 = 1 is set in order to permit the reflection of the learning value. Otherwise, the process proceeds to step 10, and the learning value reflection permission flag fel2 = 0 in order to prohibit the reflection of the learning value. To do.
[0109]
The learning value reflection counter is incremented when Steps 2 to 5 are established (Step 6) and reset when Steps 2 to 5 are not established (Step 7).
[0110]
FIG. 28 is for setting the learning permission flag FERN. In step 1, the engine rotational speed Ne, the target fuel injection amount Qsol, the actual EGR rate Megrd, and the water temperature Tw are read.
[0111]
The learning permission condition is determined by checking the contents of steps 2 to 7 and 10 one by one, and learning is permitted when all of the items are satisfied, and learning is prohibited when one of the items is contrary. . That is,
Step 2: Megrd exceeds a predetermined value MEGRLN # (that is, EGR operating 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 the rotational speed range where the engine is stalled),
Step 6: The feedback permission flag fefb = 1.
Step 7: The learning value reflection permission flag FERN2 = 1.
Step 10: The learning delay counter Ctrlln exceeds a predetermined value TMRLN # (for example, about 4 seconds)
At this time, the learning permission flag feln = 1 is set in order to permit the learning in step 11; otherwise, the process proceeds to step 12 and the learning permission flag fel = 0 is set to prohibit the learning.
[0112]
The learning delay counter is incremented when Steps 2 to 7 are established (Step 8) and reset when Steps 2 to 7 are not established (Step 9).
[0113]
Returning to FIG. 25, among the three flags set in this way, the feedback permission flag fefb is seen in step 4. When fefb = 1, the feedback correction coefficient Kqac00 for the EGR amount and the feedback correction coefficient Kqac0 for the EGR flow velocity are calculated in steps 5 and 6. 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.
[0114]
Here, the calculation of the EGR amount feedback correction coefficient Kqac00 will be described with reference to the flow of FIG. 29, and the calculation of the EGR flow velocity feedback correction coefficient Kqac0 will be described with reference to the flow of FIG.
[0115]
First, in FIG. 29 (subroutine of step 5 in FIG. 25), in step 1, the target intake air amount delay processing value tQacd, the actual intake air amount Qac, the engine rotational speed Ne, the target fuel injection amount Qsol, and the water temperature Tw are read.
[0116]
In step 2, for example, a map containing the content of FIG. 30 is searched from Ne and Qsol, for example, and the correction gain Gkfb of the EGR flow rate is obtained. In step 3, the water temperature correction coefficient Kgfbtw of the correction gain is obtained from Tw, for example, Each of them is calculated by searching the table, etc.
[0117]
[Expression 12]
Kqac00 = (tQacd / Qac-1) × Gkfb × Kgfbtw + 1
The EGR amount feedback correction coefficient Kqac00 is calculated by the following equation.
[0118]
The first term (tQacd / Qac-1) on the right side of this equation is the error rate from the target intake air amount delay processing value, and by adding 1 to this, Kqac00 becomes a value centered on 1. Equation 12 calculates the EGR amount feedback correction coefficient Kqac00 in proportion to the error rate from the target intake air amount delay processing value.
[0119]
Next, in FIG. 32 (subroutine of step 6 in FIG. 25), 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.
[0120]
In step 2, for example, a map containing the contents of FIG. 33 is searched from Ne and Qsol, and the correction gain Gkfbi of the EGR flow velocity is retrieved. In step 3, the water temperature correction coefficient Kgfbitw of the correction gain is derived from Tw. Each of them is calculated by searching the table, etc.
[0121]
[Formula 13]
Rqac0 = (tQacd / Qac-1) × Gkfbi × kGfbitw + Rqac0_n-1,
However, Rqac0_n-1: Previous Rqac0,
The error rate Rqac0 is updated by the following formula, and a value obtained by adding 1 in step 5 to the error rate Rqac0 is calculated as a feedback correction coefficient Kqac0 of the EGR flow velocity Cqe (described later in FIG. 38).
[0122]
This calculates the EGR flow velocity feedback correction coefficient Kqac0 in proportion to the integrated value (integrated value) of the error rate (tQacd / Qac-1) from the target intake air amount delay processing value (integral control).
[0123]
As shown in FIGS. 30 and 33, the reason why the correction gain is set to a value according to the operation condition (Ne, Qsol) is as follows. This is because hunting occurs or does not occur depending on operating conditions even with the same gain, so that the correction gain is reduced in a region where hunting occurs. The reason why the value is reduced when the water temperature is low (before completion of warm-up) as shown in FIGS. 31 and 34 is to stabilize the engine in a low water temperature region where the engine rotation is unstable.
[0124]
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. When the learning reflection permission flag FERN2 = 1 (when the learning value is permitted to be reflected), the process proceeds to step 10, and the error rate learning value Rqac is read by searching the learning map of FIG. 35, for example, from Ne and Qsol. A value obtained by adding 1 to is calculated as an EGR flow rate learning correction coefficient Kqac. On the other hand, when the learning reflection permission flag felrn2 = 0 (when the reflection of the learning value is prohibited), the process proceeds from step 9 to step 12, and the EGR flow rate learning correction coefficient Kqac = 1 is set.
[0125]
Subsequently, at step 13, the learning permission flag FERN is observed. If the learning permission flag ferln = 1 (when learning is permitted), the process 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 FERN = 0 (when learning is prohibited), the process proceeds from step 13 to step 15 to set the error ratio Rqacn = 0.
[0126]
Based on the error rate Rqacn thus determined, in step 16, the error rate learned value Rqac is updated. The update of the learning value will be described with reference to the flow of FIG.
[0127]
In FIG. 36 (subroutine of step 16 in FIG. 25), in step 1, the error rate Rqacn, the engine speed Ne, and the target fuel injection amount Qsol are read. In 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, the error ratio learning value Rqac is read from the learning map of FIG. 35 from Ne and Qsol. In step 4
[0128]
[Expression 14]
Rqac_n= Rqacn × Tclrn + Rqac_n-1× (1-Tclrn),
However, Rqac_n: Updated error rate learning value,
Rqac_n-1: Error ratio learning value before update (= Learning value read value)
,
The weighted average process is performed according to the following formula, and the updated learning value is stored in the learning map of FIG. 35 in step 5 (the updated value is overwritten on the previous value).
[0129]
FIG. 38 (subroutine of step 3 in FIG. 5) is for calculating the EGR flow velocity Cqe.
[0130]
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.
[0131]
[Expression 15]
Qec h = Qec × Kqac × Kqac0
The value obtained by correcting the actual EGR amount Qec with Kqac0 and Kqac is calculated as the corrected actual EGR amount Qec. Calculated as h, and this corrected actual EGR amount Qec In step 8, the EGR flow rate Cqe is calculated by searching a map having the contents shown in FIG. 39, for example, from step h and the actual EGR rate Megard. Steps 4 to 7 that have not been described will be described later.
[0132]
The characteristics of the EGR flow velocity in FIG. 39 indicate that the non-linearity is strong and the sensitivity of EGR feedback differs depending on the operating conditions, so that the EGR flow velocity feedback is small so that the difference in the feedback amount with respect to the operating conditions is small. The correction coefficient Kqac0 is used as feedback to the actual EGR amount Qec used for searching the flow velocity map.
[0133]
However, in FIG. 39, the portion near the right end where the slope of the characteristic is steep is an area where a matching error of the map tends to occur. Therefore, if there is a matching error, the EGR valve opening area Aev is affected by the matching error. Will change. That is, in Aev = Tqek / Cqe (which will be described later with reference to FIG. 40), which is an expression for calculating the EGR valve opening area Aev, an adaptation error occurs in Cqe. To cope with this, the target EGR amount Tqek However, it is necessary to correct the flow rate error. For this reason, the EGR amount feedback correction coefficient Kqac00 is newly introduced, and the target EGR amount Tqek is corrected in step 2 of FIG. 40 described later by this Kqac00.
[0134]
In this case, the above equation (12), which is an equation 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 of FIG. Can be corrected immediately. For example, in the formula (12) for simplicity, the correction gain Gkfb = 1 and Kqac00 = (tQacd / Qac−1) +1 is considered after 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, and thereby the target EGR amount Tqek is immediately decreased. When the target EGR amount Tqek is immediately reduced, the amount of fresh air (intake air amount) relatively increases, and thereby the actual intake air amount Qac converges to tQacd as a target value.
[0135]
Steps 4 to 7 in FIG. 38 which are not described are parts 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 the EGR is not operated), the process proceeds to Step 5;
[0136]
[Expression 16]
Qec h = Qac × MEGRL #,
Where MEGRL #: constant,
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,
[0137]
[Expression 17]
Megrd = MEGRL #
The actual EGR rate Megard is set by the following formula.
[0138]
The EGR flow velocity that passes through the EGR valve 6 when the EGR valve 6 is fully closed is naturally zero, but the equations 16 and 17 are parameters used for calculating the flow velocity in consideration of the start of the 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 at the start of the EGR operation (and hence the EGR flow rate) varies depending on the operating conditions, and this is addressed. In this case, the differential pressure before and after the EGR valve at the start of EGR operation is related to the actual intake air amount Qac. Therefore, Qec is proportional to Qac according to equation (16). By giving the initial value of h, the calculation accuracy of the EGR flow velocity at the start of the EGR operation is improved.
[0139]
FIG. 40 (subroutine of step 4 in FIG. 5) is for calculating the EGR valve opening area Aev. In step 1, the target EGR amount Tqec, the EGR amount feedback correction coefficient Kqac00, and the EGR flow velocity Cqe are read per cylinder. In step 2, the target EGR amount Tqec per cylinder is corrected by an EGR amount feedback correction coefficient Kqac00 (Tqec / Kqac00).
[0140]
[Expression 18]
Tqek = Tqec × (Ne / KCON #) / Kqac00,
However, Kqac00: EGR amount feedback correction coefficient,
KCON #: constant,
Unit conversion (per cylinder → per unit time) is performed by the following formula to obtain the target EGR amount Tqek, and in step 3 from the target EGR amount Tqek and the EGR flow velocity Cqe
[0141]
[Equation 19]
Aev = Tqek / Cqe
The EGR valve opening area Aev is calculated by the following formula.
[0142]
The EGR valve opening area Aev obtained in this way is converted into a lift amount of the EGR valve 6 by searching a table having the contents shown in FIG. 6 in a flow (not shown) so that the EGR valve lift amount becomes this EGR valve lift amount. A duty control signal is generated for the pressure control valve 5, and this duty control signal is output to the pressure control valve 5.
[0143]
Next, FIG. 41 is for calculating the control command duty value Dtyvnt to be given to the actuator 54 and is executed at regular intervals (for example, every 10 ms). Since FIG. 41 is also a main routine, the explanation will focus on subroutines prepared for the processing of each step.
[0144]
FIG. 42 (subroutine of step 1 in FIG. 41) is for setting the overboost determination flag FOVBST.
[0145]
First, in step 1, the engine rotational speed Ne, the target fuel injection amount Qsol, the actual intake air amount Qac, and Ne (values before the k (integer constant) cycle) are obtained._nk, Qsol_nk, Qac_nkIn addition, the actual EGR rate Megard is read.
[0146]
In Step 2, using the actual intake air amount Qac and the actual EGR rate Megard
[0147]
[Expression 20]
Qcyl = Qac × (1 + Megrd / 100)
The amount of gas Qcyl [mg / st. cyl]. The second term (Qac × Megrd / 100) on the right side of Equation 20 is the actual EGR amount, and the amount of gas sucked into the cylinder by adding the actual EGR amount to the actual intake air amount Qac (fresh air amount). It is said.
[0148]
Note that the actual EGR amount Qec in FIG. 24 may be used as the actual EGR amount (thus, at this time, Qcyl = Qac + Qec).
[0149]
In step 3
[0150]
[Expression 21]
Qexh = (Qac + Qsol × GKQFVNT #) × Ne / KCON #,
Where GKQFVNT #: conversion factor,
KCON #: constant,
The actual displacement Qexh [mg / st. cyl]. This means that the sum of the amount of Qsol fuel combusted and exhausted and the actual intake air amount Qac is the exhaust amount (ignoring the rise in temperature). Here, the unit of Qsol is [mm.^Three/ St. cyl], the conversion factor GKQFVNT # [mg / mm^Three] To convert the unit of Qexh to Qac [mg / st. cyl]. The multiplication by Ne / KCON # is [mg / st. cyl] to [g / s].
[0151]
In step 4, the difference between Ne, Qsol, Qac and the value before k cycles is calculated as an engine speed change amount DNE, a fuel injection amount change amount DQSOL, and an actual intake air amount change amount DQAC, and these engine speed Ne. Based on the target fuel injection amount Qsol, it is determined in steps 5 to 7 whether or not overboost occurs. That is,
Step 5: Ne ≧ predetermined value KNEOB # and DNE ≧ predetermined value KDNEOB #.
Step 6: Qsol ≧ predetermined value KQFOB # and DQSOL ≧ predetermined value KDQFOB #
Step 7: DQAC ≧ predetermined value KDQACOB #
When either of the above conditions is satisfied, it is determined that overboost occurs, and the process proceeds to steps 11 and 12 to set the overboost determination flag FOVBT = 1 and reset the overboost timer TMROB (TMROB = 0).
[0152]
As will be described later with reference to FIGS. 54 and 59, this flag FOVBST is used for calculation of the target ratio basic value Rvnt0. When the flag FOVBT = 1 under the same conditions, the flag FOVBT = 0 is larger than when the flag FOVBT = 0. A target ratio basic value Rvnt0 of the value is calculated. As the target ratio basic value Rvnt0 becomes smaller, the variable nozzle 53 is closed and the supercharging pressure becomes higher. Therefore, when the flag FOVBT = 1, the variable nozzle 53 is made more open than when the flag FOVBT = 0 (supercharging). This makes it difficult for the pressure to rise). That is, when the flag FOVBT = 1, the overboost is suppressed, while when the flag FOVBT = 0 is the normal operation.
[0153]
The overboost timer TMROB is for measuring an elapsed time after the flag FOVBT is switched to 1. Although not shown, the timer TMROB is reset only when the flag FOVBT is changed from 0 to 1, and the second and subsequent passes are skipped (the process of step 12 is skipped). The timer TMROB may be constituted by, for example, an internal timer of the CPU, and the timer value increases with time by resetting the timer.
[0154]
When the change when the accelerator pedal is suddenly depressed is shown in FIG. 43 as a model, the timing for determining the occurrence of overboost is the target fuel injection amount Qsol, engine rotational speed Ne, and actual intake air amount Qac in this order. Each time, the flag FOVBT = 1. This is because the determination timing is slow when trying to determine the occurrence of overboost based only on the actual intake air amount Qac, so if the accelerator pedal is depressed suddenly, the response to overboost will be delayed and overboost will occur. Therefore, the target fuel injection amount Qsol and the engine rotation speed Ne are added as parameters for overboost determination, and the overboost determination timing is advanced as much as possible.
[0155]
FIG. 43 shows a case where Qsol is a small value due to the smoke limit restriction at the beginning of the transition so that the time lag of the signals of the three parties (Qsol, Ne, Qac) can be clearly understood. . Therefore, when there is a fuel limit of the smoke limit in this way and an attempt is made to determine the occurrence of overboost based only on the actual intake air amount Qac, the determination timing is greatly delayed. Even when the fuel limit of the smoke limit is involved, a time margin is created for coping with overboost suppression, and overboost can be reliably prevented.
[0156]
If none of the above three conditions shown in Steps 5 to 7 is satisfied, the process proceeds from Steps 5, 6, and 7 to Steps 8 and 9 in FIG.
[0157]
Steps 8 and 9 are portions for determining whether or not overboost occurs based on the cylinder intake gas amount Qcyl and the actual exhaust amount Qexh. Explaining this, FIG. 110 shows one experimental result obtained by changing the opening ratio of the variable nozzle 53 (described later), the engine rotational speed Ne, and the target fuel injection amount Qsol as the engine load in one engine. The cylinder intake gas amount Qcyl (= Qac + Qec) due to a difference in operating conditions (Ne, Qsol) or a difference in opening ratio even if the operating conditions are the same even if the opening ratio of the variable nozzle 53 is the same even though the engine is the same. ) And the actual displacement Qexh is considerably different. This variation is due to manufacturing variations of the air flow meter 39, the actuator 54, and the like. Due to such variations in Qcyl and Qexh, over-boost occurs under conditions plotted exceeding the supercharging limit. Therefore, in order to prevent overboost due to variations in Qcyl and Qexh, a supercharging limit that changes according to the actual displacement Qexh is set in advance as a determination value in a table, Qcyl calculated during operation, and its From the comparison result with the determination value obtained by searching the table from the actual displacement Qexh at the time, when over boost occurs when Qcyl is greater than or equal to the determination value, conversely, over boost occurs when Qcyl is less than the determination value It is judged that there is no.
[0158]
Since the two embodiments are of a type that employs the intake air amount as equivalent to the supercharging pressure, the cylinder intake gas amount Qcyl is taken on the vertical axis. It becomes supercharging pressure. This is shown in FIG. 111. In this case as well, similar to FIG. 110, the variable nozzle opening ratio and operating conditions (Ne, Qsol) are the same engine due to manufacturing variations of the supercharging pressure sensor and the actuator. ), The actual supercharging pressure and the actual displacement Qexh vary considerably, and due to the variation in the actual supercharging pressure and Qexh, overboost occurs when the conditions are plotted beyond the supercharging limit. Therefore, in order to prevent overboost due to variations in actual supercharging pressure and Qexh, a supercharging limit that changes in accordance with the actual displacement Qexh is set in a table in advance as a judgment value and detected during operation. If overboost occurs when the actual boost pressure is greater than or equal to the determination value based on the comparison result between the actual boost pressure and the determination value obtained by searching the table from the actual displacement Qexh at that time, conversely, What is necessary is just to determine that an overboost does not arise when a supercharging pressure is less than a determination value.
[0159]
Specifically, an overboost determination intake gas amount TQcyl (determination value) is calculated by searching a map containing, for example, FIG. 44 from the actual exhaust amount Qexh in step 8 of FIG. 42, and the above cylinder intake gas amount Qcyl is calculated. And this TQcyl are compared in step 9 of FIG. When Qcyl is equal to or higher than TQcyl, it is determined that overboost occurs, and the processing of steps 11 and 12 is executed.
[0160]
On the other hand, when Qcyl is less than TQcyl, overboost does not occur, so the routine proceeds from step 9 to step 10, where the overboost determination flag FOVBST = 0.
[0161]
As shown in FIG. 44, the overboost determination intake gas amount TQcyl is a characteristic that is substantially mountain-shaped with respect to the actual exhaust amount Qexh. This takes into account the efficiency characteristics of the turbocharger shown in FIG. That is, in FIG. 45, in the turbocharger, the efficiency η (fresh air amount) increases as the actual displacement Qexh increases from a small value, and the efficiency η decreases as the actual displacement Qexh further increases. TQcyl is set. The vertical axis represents the pressure ratio (manifold pressure Pm / atmospheric pressure Pa).
[0162]
Moreover, it is preferable to make TQcyl smaller as the atmospheric pressure Pa becomes lower even with the same actual displacement Qexh (see FIG. 44).
[0163]
FIG. 46 (subroutine of step 2 in FIG. 41) is for setting the overboost release transition flag FCLROB. The reason for introducing this flag FCLROB is as follows. Suppression of overboost is performed for a predetermined time (overboost suppression time TTMROB described later). However, if the variable nozzle 53 is immediately returned to the closed side (the side where the boost pressure rises) just after the time has elapsed, there is a risk that overboost will occur. Therefore, this overboost release transition flag FCLROB is introduced, and as shown in FIG. 47, this overboost release transition flag is set at a timing when the overboost determination flag FOVBST is changed from 1 to 0 (that is, timing at which overboost suppression is finished). FCLROB is switched from 0 to 1, and the variable nozzle 53 is slowly returned to the position before the overboost suppression start during the period in which the overboost release transition flag FCLROB = 1.
[0164]
The flow will be specifically described. In step 1 of FIG. 46, the overboost timer TMROB and the overboost determination flag FOVBST are observed. When the overboost timer TMROB is equal to or shorter than the overboost suppression time TTMROB or when the overboost determination flag FOVBST = 1, the overboost is being suppressed, and the process proceeds to step 4 to continue the state of the overboost determination flag FOVBST = 1.
[0165]
On the other hand, in other cases (for example, when the overboost timer TMROB exceeds the overboost suppression time TTMROB or when the condition that overboost occurs while the overboost is being suppressed is not satisfied), step 1 to step 2 In step 3, the overboost determination flag FOVBST is set to 0 and the overboost clear timer TMRCLROB is reset (TMRCLROB = 0) in order to end overboost suppression and return to normal operation.
[0166]
The overboost clear timer TMRCLROB is for measuring the elapsed time after the overboost determination flag FOVBST = 0. Although not shown, the timer TMRCLROB is reset only at the timing when the overboost determination flag FOVBST is switched from 1 to 0, and the second and subsequent times are passed (step 3 is skipped). This timer TMRCLROB may also be constituted by, for example, an internal timer of the CPU, and the timer value increases with time by resetting this timer.
[0167]
In step 5, the timer TMRCLROB is compared with the overboost release transition time TTMRCLROB. Immediately after resetting the timer TMRCLROB, TMRCLROB <TTMRCLROB, so the routine proceeds to step 7 where the overboost release transition flag FCLROB = 1.
[0168]
From the next time (that is, after 10 ms), the process proceeds to Steps 1, 2, and 5, and the timer TMRCLROB is compared with the overboost release transition time TTMRCLROB. While TMRCLROB is equal to or less than TTMRCLROB, the process of step 7 is repeated. When the timer TMRCLROB exceeds TTMRCLROB, the process proceeds from step 5 to step 6 to set the overboost release transition flag FCLROB = 0. This shifts to normal operation.
[0169]
The overboost suppression time TTMROB and the overboost release transition time TTMRCLROB used in FIG. 46 are always calculated (for example, every 10 ms) as shown in FIGS.
[0170]
First, referring to FIG. 48, in step 1, over-boost control time basic value TTMROB0 is obtained by searching a map containing, for example, FIG. 49 from engine speed change amount DNE and fuel injection amount change amount DQSOL. By searching a map having the content of FIG. 50 from the actual intake air amount change amount DQAC and the deviation of the cylinder intake gas amount Qcyl from the overboost determination intake gas amount TQcyl, the overboost control time correction coefficient KTMROB is obtained. In step 3, the product is calculated as an overboost suppression time TTMROB. Note that the calculation method of DQSOL, DNE, DQAC, Qcyl, and TQcyl is the same as that in FIG. 42 and is not shown in the flow of FIG.
[0171]
As shown in FIG. 49, the overboost control time basic value TTMROB0 is increased as DNE or DQSOL increases for the following reason. Overboost is more likely to occur as the change in the engine speed Ne or the target fuel injection amount Qsol as the engine load increases. Therefore, the overboost suppression time becomes longer as the change in Ne or Qsol is larger (that is, as DNE or DQSOL is larger). As shown in FIG. 50, the larger the DQAC and Qcyl-TQcyl are, the larger the value of the correction coefficient KTMROB is because the change in the actual intake air amount Qac (that is, DQAC) and the deviation from the determination value (that is, Qcyl-TQcyl). Since the overboost is more likely to occur as the value is larger, the overboost suppression time is increased accordingly.
[0172]
Next, moving to FIG. 51, in step 1, the overboost release transition time basic value TTMRCLROB0 is obtained by searching a table containing, for example, FIG. 52 from the atmospheric pressure Pa detected by the atmospheric pressure sensor 38 (see FIG. 1). In step 2, the correction coefficient KTMRCLOB for the overboost release transition time is calculated from the actual displacement Qexh (obtained in step 3 of FIG. 42), for example, by searching a table having the contents shown in FIG. Is calculated as overboost release transition time TTMRCLROB in step 3.
[0173]
The reason why the overboost release transition time basic value TTMRCLROB0 is increased under the condition (for example, high altitude) where the atmospheric pressure Pa becomes low as shown in FIG. 52 is as follows. The displacement increases according to the pressure difference between the exhaust pressure and the atmospheric pressure, so the displacement increases under conditions where the atmospheric pressure is low, and the work performed by the turbocharger increases accordingly (overboost tends to occur) ). Therefore, the overboost release transition time basic value TTMRCLROB0 is increased under conditions where the atmospheric pressure Pa is low. The reason why the overboost release transition time correction coefficient KTMRCLROB is increased in the region where the actual exhaust amount Qexh is equal to or greater than a predetermined value as shown in FIG. 53 is that overboost tends to occur when the actual exhaust amount Qexh exceeds the predetermined value. Accordingly, the overboost release transition time is increased in a region where the actual displacement Qexh exceeds a predetermined value.
[0174]
54 and 59 (subroutine of step 3 in FIG. 41) are for calculating the target opening ratio Rvnt of the variable nozzle 53 (FIG. 54 is the first embodiment and FIG. 59 is the second embodiment).
[0175]
Here, the opening ratio of the variable nozzle 53 is the ratio of the current nozzle area to the nozzle area when the variable nozzle 53 is fully opened. Therefore, the opening ratio is 100% when the variable nozzle 53 is fully opened, and the opening ratio is 0% when the variable nozzle 53 is fully closed. The reason for adopting the opening ratio is to provide versatility (a value not related to the turbocharger capacity). Of course, the opening area of the variable nozzle may be adopted.
[0176]
In addition, since the turbocharger of the embodiment is a type in which the supercharging pressure is the smallest when fully opened and the supercharging pressure is highest when fully closed, the supercharging pressure becomes higher as the opening ratio is smaller.
[0177]
First, referring to FIG. 54 of the first embodiment, in step 1, the target intake air amount tQac, the actual EGR amount Qec, the engine speed Ne, the target fuel injection amount Qsol, and the target EGR rate Megr are read.
[0178]
In steps 2 and 3,
[0179]
[Expression 22]
tQas0 = (tQac + Qsol × QFGAN #) × Ne / KCON #,
Qes0 = (Qec + Qsol × QFGAN #) × Ne / KCON #,
Where QFGAN #: gain,
KCON #: constant,
The intake air amount equivalent value tQas0 (hereinafter, this intake air amount equivalent value is referred to as “set intake air amount equivalent value”) for setting the target opening ratio basic value, and the target opening ratio basic value EGR amount equivalent value Qes0 (hereinafter, this EGR amount equivalent value is referred to as "set EGR amount equivalent value") is calculated. In Equation 22, Qsol × QFGAN # is added to tQac and Qec so 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 gain QFGAN #. The adjustment is done with Further, Ne / KCON # is a value for converting into an intake air amount and an EGR amount per unit time.
[0180]
Steps 4 to 10 are based on the target EGR rate Megr and the overboost determination flag FOVBST.
<1> Megr ≧ predetermined value KEMRAV # and FOVBST = 1 (EGR operating range and overboost suppression)
<2> Megr ≧ predetermined value KEMRAV # and FOVBST = 0 (EGR operating range and normal operation)
<3> Megr <predetermined value KEMRAV # and FOVBST = 1 (when EGR is not operating and overboost is suppressed)
<4> When Megr <predetermined value KEMRAV # and FOVBST = 0 (EGR non-operating range and normal operation)
In this case, the optimum opening ratio in each of the four cases is set as the target opening ratio basic value Rvnt0 (supercharger operation target value). That is, in the case of <1>, in step 7, the map corresponding to FIG. 55 is searched from the set intake air amount equivalent value tQas0 and the set EGR amount equivalent value tQes0, and in the case of <2>, tQas0 is also set in step 8. For example, a target opening ratio basic value Rvnt0 is set by searching a map having the contents shown in FIG. 56 from tQes0. Similarly, in the case of <3>, a map containing, for example, FIG. 57 is retrieved from tQas0 and the target fuel injection amount Qsol in step 10, and in the case of <4>, for example, FIG. 58 from tQas0 and Qsol in FIG. The target opening ratio basic value Rvnt0 is set by searching a map having the contents of.
[0181]
On the other hand, FIG. 59 of the second embodiment differs from the first embodiment only in that the target EGR rate Megr is used instead of the set EGR amount equivalent value Qes0 (therefore, there is no step 3 in FIG. 54). That is, a map containing, for example, FIG. 60 from tQas0 and Megr at step 7 when <1>, and a map containing, for example, FIG. 61 from tQas0 and Megr at step 8 when <2>. To set the target opening ratio basic value Rvnt0.
[0182]
Since others are the same as those of the first embodiment, description of the flow is omitted.
[0183]
Here, the characteristics shown in FIGS. 60 and 61 are different from those shown in FIGS. 55 and 56, although the vertical axis is different from those shown in FIGS. The characteristics of the basic value Rvnt0 will be described.
[0184]
As shown in FIGS. 55 and 56, the target opening ratio basic value is decreased as the set EGR amount equivalent value Qes0 increases in the region on the right side of the large set intake air amount equivalent value tQas0. This is because when the EGR amount increases, the fresh air decreases, and as a result, smoke is generated when the air-fuel ratio leans to the rich side. Therefore, as the EGR amount increases, the target opening ratio basic value decreases and the boost pressure increases. It is necessary.
[0185]
Also, the tendency of the target opening ratio basic value represented in FIGS. 55 and 56 is common to fuel efficiency and exhaustion, and the difference between the two is a specific numerical value. For example, the minimum value in the figure is the value at which the turbocharger works efficiently, so it is the same for both the fuel efficiency-oriented setting example and the exhaustion-oriented setting example. Unlike the setting example of FIG. 1 and the setting example of emphasizing exhaust, when tQas0 and Qes0 are the same, the setting example of emphasizing fuel consumption becomes larger. Note that the target opening ratio basic value can also be set as an example of setting emphasis on acceleration.
[0186]
Here, which of the three characteristics of emphasis on fuel consumption, emphasis on exhaust, and emphasis on acceleration will be described collectively with reference to FIG. 62 (however, in the case of <1> and <2> above). Indicates how the fuel consumption, exhaust (NOx and PM), and intake air amount change when the EGR rate is varied between large and small, under the conditions of constant engine speed and engine torque. It is a thing. From the figure, even if the engine speed and the engine torque are the same, the opening area of the variable nozzle that provides the best fuel consumption, the opening area of the variable nozzle that provides the best exhaust, and the intake air volume are maximized (that is, the acceleration is best). It can be seen that the opening areas of the variable nozzles are different. Therefore, for example, in order to create a characteristic with emphasis on fuel consumption, the engine rotational speed and the engine torque are made different to obtain a large number of data on the opening area (opening ratio) at which the fuel consumption is the best, and these data are revised to tQas0 and Qes0 ( It is only necessary to assign to a map using Megr) as a parameter.
[0187]
Next, the target opening ratio basic value at the time of overboost suppression (see FIGS. 55 and 57 in the first embodiment, and FIGS. 60 and 57 in the second embodiment) is used as the target opening ratio basic value (first value in the normal operation). 56 and 58 in the embodiment, and in FIGS. 61 and 58 in the second embodiment. This is because, in order to suppress overboost, the boost pressure should be reduced, that is, the variable nozzle 53 should be opened (Rvnt0 is increased).
[0188]
The setting of the target opening ratio basic value is not limited to the above. In the first embodiment, as shown in FIGS. 55 and 56, the target opening ratio basic value is set from the set intake air amount equivalent value tQas0 and the set EGR amount equivalent value Qes0, but instead, the target intake air amount is set. It may be set from tQac and actual EGR amount Qec. Further, instead of this, the target intake air amount tQac and the target EGR amount (Qec0) may be set. Similarly, in the second embodiment, as shown in FIGS. 60 and 61, the target opening ratio basic value is set from the set intake air amount equivalent value tQas0 and the target EGR rate Megr, but instead of this, the target intake air It may be set from the amount tQac and the actual EGR rate Megard. Further, instead of this, the target intake air amount tQac and the target EGR rate Megr may be set.
[0189]
Thus, based on the target intake air amount tQac and the actual EGR amount Qec, and on the basis of the target intake air amount tQac and the actual EGR rate Megrd, the target opening ratio basic value Rvnt0 that is the operation target value of the supercharger is set. If set, even if the target EGR amount (Qec0), which is the control target value of the EGR device, or the target EGR rate Megr changes, the target intake air amount that optimizes fuel consumption, exhaust, and acceleration can be obtained. As a result, the controllability of the turbocharger and the EGR device including the engine can be improved, and thereby the mutual performance can be sufficiently exhibited. In addition, adaptation can be simplified and logic can be simplified.
[0190]
In particular, during a transition, even if the target EGR amount or the target EGR rate Megr changes stepwise, there is a delay until the actual EGR amount Qec or the actual EGR rate Megrd catches up with the target EGR amount or the target EGR rate Megr, and the target EGR amount. There is a possibility that the target opening ratio basic value Rvnt0 has an error corresponding to the deviation from the target EGR rate Megr, and the target intake air amount that optimizes fuel consumption, exhaust, and acceleration may not be obtained. In setting Rvnt0, if the actual EGR amount Qec, which is a value obtained by subjecting the target EGR amount to delay processing, and the actual EGR amount Megrd, which is a value obtained by subjecting the target EGR rate Megr to delay processing, are used even in a transient state. The turbocharger can be controlled to obtain a target intake air amount that optimizes fuel consumption, exhaust, and acceleration.
[0191]
In FIG. 54, in step 11, the overboost release transition flag FCLROB is observed. When FCLROB = 1 (at the time of overboost release transition), proceed to step 13,
[0192]
[Expression 23]
Rvnt = (1 / TMRCLROB #) × Rvnt0 + (1- (1 / TMRCRLOB #)) × Rvnt_n-1,
TMRCLROB #: Time constant
Rvnt_n-1: Last Rvnt,
The target opening ratio Rvnt is calculated by performing a delay process on the target opening ratio basic value Rvnt0. The process at the time of overboost release transition is to close the variable nozzle 53 (the side where the boost pressure rises) suddenly after the variable nozzle 53 is opened (the side where the boost pressure does not rise) when overboost is suppressed. If it is returned to, over-boost may occur due to this, so the variable nozzle 53 is slowly returned to the closed side.
[0193]
When the flag FCLROB becomes 0 (overboost release transition ends), the process proceeds from step 11 to step 12, and the target opening ratio basic value Rvnt0 is set as the target opening ratio Rvnt as it is.
[0194]
FIG. 63 (subroutine of step 4 in FIG. 41) performs advance processing to compensate for the dynamics of the intake system with respect to the target opening ratio Rvnt obtained as described above.
[0195]
The response delay of the new air amount with respect to the control command value to the actuator 54 includes a response delay of the intake / exhaust gas flow, a turbo lag, and a response delay of the actuator 54 itself. Including the delay, the response of the actuator 54 itself is separated from the response delay of the intake / exhaust gas flow including the turbo lag (this delay is hereinafter referred to as “supercharger / intake / exhaust response delay”) and the actuator 54 itself. The process proceeds independently for each response delay.
[0196]
Of these, in FIG. 63, the advance processing is performed considering only the response delay of the turbocharger / intake and exhaust (see FIG. 85 for the advance processing considering only the response delay of the actuator 54). In this case, since the time constant of the response delay of the turbocharger / intake and exhaust greatly depends on the exhaust amount, the advance correction gain Gkvnt and the advance correction time constant equivalent value Tcvnt are set using the exhaust amount as a parameter. Furthermore, the response time constant differs between when the variable nozzle 53 is moved to the opening side and when the variable nozzle 53 is moved to the closing side. This will be described in detail below.
[0197]
In FIG. 63, the target opening ratio Rvnt, the target intake air amount delay processing value tQacd, the target fuel injection amount Qsol, and the engine speed Ne are read in Step 1, and in Step 2,
[0198]
[Expression 24]
Tqexh = (tQacd + Qsol × QFGAN #) × Ne / KCON #,
Where QFGAN #: gain,
KCON #: constant,
The actual displacement equivalent value Tqexh [mg / st. cyl]. This Tqexh is a value obtained by using the target intake air amount delay processing value tQacd instead of the target intake air amount tQac in the upper equation for obtaining the set intake air amount equivalent value tQas0 in the equation (22). This is a signal that changes with a time constant that is substantially the same as the time constant when the actual displacement responds. For example, FIG. 64 shows the change when the target fuel injection amount Qsol is increased stepwise, and the actual exhaust amount equivalent value Tqexh (the lowermost step) with respect to the actual change in the exhaust amount (see the lowermost broken line). (See the solid line in Fig. 2).
[0199]
In step 3 of FIG. 63, the target opening ratio Rvnt and the previous predicted opening ratio Cavnt_n-1Compare Here, the expected opening ratio Cavnt is a weighted average value of the target opening ratio Rvnt, as will be described later (see step 11 in FIG. 63).
[0200]
Rvnt> Cavnt_n-1If it is (when the variable nozzle 53 is moved to the opening side), the process proceeds to steps 4 and 5 to advance and correct the value TGKVNTO obtained by searching a table containing, for example, FIG. 65 from the actual exhaust amount equivalent value Tqexhd. For example, a value TTCVNTO obtained by searching a table having the contents shown in FIG. 67, for example, from the actual exhaust amount equivalent value Tqexhd is set as the time constant equivalent value Tcvnt for the advance correction, and Rvnt <Cavnt_n-1(When the variable nozzle 53 is moved to the closing side), the process proceeds to Steps 7 and 8, and the value TGKVNTC obtained by searching a table having the content of FIG. 66, for example, from the actual exhaust amount equivalent value Tqexhd is advanced. For example, a value TTCVNTC obtained by searching a table having the contents shown in FIG. 68, for example, from the actual exhaust amount equivalent value Tqexhd as the correction gain Gkvnt is set as the time constant equivalent value Tcvnt for the advance correction. Rvnt and Cavnt_n-1Are the same, the process proceeds to Steps 9 and 10, and the previous advance correction gain and the advance correction time constant equivalent value are maintained in order to ensure the stability of the advance process.
[0201]
The table values TGKVNTO and TGKVNTC for determining the advance correction gain Gkvnt are values that increase as the actual exhaust amount equivalent value Tqexhd decreases, as shown in FIGS. This is because the response delay of the supercharger / intake / exhaust increases as the displacement decreases, and the advance correction gain Gkvnt increases as the displacement decreases. Further, even when the actual exhaust amount equivalent value Tqexhd is the same, when the variable nozzle 53 is moved to the closing side (FIG. 66), the table value is larger on the closing side than when the variable nozzle 53 is moved to the opening side (FIG. 65). This is because the boosting pressure is less likely to move, so it is necessary to increase the correction gain.
[0202]
The table values TTCVNTO and TTCVNTC for determining the time constant equivalent value Tcvnt for the advance correction are values that become smaller as the actual exhaust amount equivalent value Tqexhd becomes smaller as shown in FIGS. This is because the time constant of the response delay of the turbocharger / intake / exhaust increases as the displacement decreases, so the time constant increases as the displacement decreases (therefore, the time constant equivalent value Tcvnt, which is in a relationship inverse to the time constant) The smaller the smaller the displacement, the smaller. Further, even when the actual exhaust amount equivalent value Tqexhd is the same, when the variable nozzle 53 is moved to the closing side (FIG. 68), the table value is smaller on the closing side than when the variable nozzle 53 is moved to the opening side (FIG. 67). Since the time constant is larger when moving it, it matches this.
[0203]
In step 11 of FIG. 63, using the time constant equivalent value Tcvnt and the target opening ratio Rvnt of the advance correction thus obtained,
[0204]
[Expression 25]
Cavnt = Rvnt × Tcvnt + Cavnt_n-1× (1-Tcvnt),
However, Cavnt_n-1: Last Cavnt,
The expected opening ratio Cavnt is calculated by the following formula, and from this value and the target opening ratio Rvnt, in step 12,
[0205]
[Equation 26]
Avnt f = Gkvnt × Rvnt− (Gkvnt−1) × Cavnt_n-1,
However, Cavnt_n-1: Last Cavnt,
The feed forward amount Avnt of the target aperture ratio f is calculated. The advance process itself in steps 11 and 12 is basically the same as the advance process shown in steps 4 and 5 of FIG.
[0206]
Furthermore, in step 13 of FIG.
[0207]
[Expression 27]
Rvnt = Rvnt × TCVNT # + (1−TCVNT #) × Rvnt_n-1,
Where TCVNT #: time constant of response delay of actuator 54,
Rvnte_n-1: Last Rvnt,
The actual opening ratio Rvnt is calculated by performing a delay process on the target opening ratio Rvnt. The time constant TCVNT # of the response delay of the actuator 54 itself is a constant value because it does not change when the actuator 54 is moved to the opening side or the closing side of the variable nozzle 53.
[0208]
This actual opening ratio Rvnt is calculated as a PI gain opening ratio correction coefficient Gkvavnt (step 7 in FIG. 72, FIG. 76) when setting a feedback gain, which will be described later, and an opening ratio reflecting coefficient Gkvntlav used in the reflecting area of the opening ratio learning value. Is used for the calculation (step 9 in FIG. 80, FIG. 83).
[0209]
FIG. 69 (subroutine of step 5 in FIG. 41) shows an opening ratio correction value (opening ratio feedback amount Avnt). fb and the aperture ratio learning value Ravlr), which are executed at regular intervals (every 10 ms). FIG. 69 is a subroutine for FIG. 41, but a lower-level subroutine is prepared for the processing of each step of FIG. 69, and thus this lower-level subroutine will be mainly described.
[0210]
FIG. 70 (subroutine of step 1 in FIG. 69) is for performing permission determination of feedback of the aperture ratio.
[0211]
First, in step 1, it is determined whether or not the aperture ratio is in the feedback region. As shown in FIG. 71, the feedback area (abbreviated as F / B area in the figure) is the remaining area excluding the low load and low flow area. The reason for excluding the low load and low flow area is that the fresh air amount can hardly be changed in this region even if the opening ratio of the variable nozzle 53 is changed (that is, the sensitivity of the fresh air amount to the change in the opening ratio is small). It is small). Accordingly, it is possible to improve the stability of intake air amount control (supercharging pressure control) in a region where the sensitivity of the exhaust amount with respect to the change in the opening ratio is small.
[0212]
A hysteresis region is provided at the boundary between the feedback region and the non-feedback region.
[0213]
If the operating condition (Ne, load) is in the feedback region, the feedback region flag FVNFBNEQF = 1 is set in step 2 of FIG. 70, and if not, the flag FVNFBNEQF = 0 is set in step 3.
[0214]
In steps 4 to 6, FCLPVNDTY, which is the previous value of the target EGR rate Megr and the command opening ratio clamp flag FCLPVNDTY (described later in FIG. 85)._n-1Based on the air flow meter failure flag FDGMAF, it is determined whether or not the feedback permission condition for the opening ratio is satisfied. That is,
Step 4: Megr> predetermined value KVNFBMEGR # (EGR operating range),
Step 5: FCLPVNDTY_n-1= 1 (when the command opening ratio Avnt is clamped),
Step 6: FDGMAF = 1 (at the time of air flow meter failure)
When either of the above conditions is established, the routine proceeds to step 8 where the feedback permission flag FVNFB = 0 is set to prohibit the feedback of the opening ratio, and otherwise, the routine proceeds to step 7 where the flag FVNFB = 1 is set.
[0215]
The reason why the feedback of the aperture ratio is prohibited in the EGR operating range is as follows. Since the EGR valve opening is feedback controlled in the EGR operating range, if the opening ratio of the variable nozzle 53 is also feedback controlled in this region, hunting occurs due to interference between the two feedback controls.
[0216]
The reason why the feedback is prohibited when the command opening ratio Avnt is clamped is as follows. The command opening ratio Avnt is clamped when the change in the command opening ratio Avnt has converged as described later (see steps 2 and 9 in FIG. 85). Therefore, when the command opening ratio Avnt is clamped, it is not necessary to further feedback control the opening ratio. Moreover, it is for fail-safe that the feedback is prohibited when the air flow meter fails.
[0217]
FIG. 72 (subroutine of step 2 in FIG. 69) is for setting a feedback gain used for feedback control of the aperture ratio.
[0218]
In step 1, the target intake air amount delay processing value tQacd, the actual intake air amount Qac, the actual exhaust amount equivalent value Tqexhd, and the actual opening ratio Rvnt are read.
[0219]
In step 2, the feedback permission flag FVNFB is checked. When the flag FVNFB = 1 (performs feedback control of the opening ratio), in step 4
[0220]
[Expression 28]
Eqac0 = Qac-tQacd
The control error Eqac0 from the target value (tQacd) of the actual intake air amount Qac is calculated by the following equation.
[0221]
Here, in normal feedback control, the target intake air amount tQac that is set according to the operating conditions becomes the target in feedback control as it is, but in this embodiment, both the dead time and the time constant of response are large control targets. As shown in Equation 28, the control error Eqac0 is obtained using the target intake air amount delay processing value tQacd as the target value in the feedback control (the same applies to step 4 in FIG. 77 described later).
[0222]
On the other hand, when the flag FVNFB = 0 (opening ratio feedback control is not performed), the process proceeds to step 3 to set the control error Eqac0 = 0.
[0223]
In step 5, the proportional gain basic value Gkvntp0 and the integral gain basic value Gkvnti0 are calculated from the control error Eqac0 by searching a table containing, for example, FIG. 73 and FIG. The dead zone is provided in FIGS. 73 and 74 in order to obtain control stability near the target value.
[0224]
In steps 6 and 7 of FIG. 72, the exhaust amount correction coefficient Gkvqexh of the PI gain is retrieved by searching a table having the content of FIG. 75, for example, from the actual exhaust amount equivalent value Tqexhd, and FIG. 76, for example, is derived from the actual opening ratio Rvnt. To calculate the PI gain opening ratio correction coefficient Gkvavnt
[0225]
[Expression 29]
Gkvntp = Gkvntp0 × Gkvqexh × Gkvavnt,
Gkvnti = Gkvnti0 × Gkvqexh × Gkvavnt,
The proportional gain Gkvntp and the integral gain Gkvnti are calculated by the following equation.
As shown in FIG. 75, the PI gain displacement correction coefficient Gkvqexh is a value that decreases as the actual exhaust amount equivalent value Tqexhd increases. This is because even if the variation ratio of the opening ratio of the variable nozzle 53 is the same, the large displacement side is closer to the target than the small displacement amount side (see FIG. 103). It is because it may be smaller than the quantity side.
[0226]
As shown in FIG. 76, the PI gain opening ratio correction coefficient Gkvavnt is a value that decreases as the actual opening ratio Rvnt decreases. Since the boost pressure is higher on the side where the variable nozzle 53 is closed (side where the actual opening ratio Rvnt is smaller) than on the side where the variable nozzle 53 is opened (side where the actual opening ratio Rvnt is larger), the variable nozzle 53 is Since the amount of fresh air changes sensitively even if the opening ratio of the variable nozzle 53 is slightly changed on the closed side (see FIG. 104), the correction coefficient decreases as the variable nozzle 53 closes accordingly. Because it is necessary to do.
[0227]
More accurate views for FIGS. 75 and 76 are shown in FIGS.
[0228]
FIG. 77 (subroutine of step 3 in FIG. 69) shows the feedback amount Avnt of the opening ratio. This is for calculating fb.
[0229]
In Steps 1 to 4, after calculating the control error Eqac in accordance with the value of the feedback permission flag FVNFB in the same manner as Steps 1 to 4 in FIG.
[0230]
[30]
Ravfbp = Gkvntp × Eqac
The proportional correction value Ravfbp is obtained from the equation
[0231]
[31]
Ravfbi = Ravfbi_n-1+ Gkvnti × Eqac-dTravlr,
However, Ravfbi_n-1: Last Ravfbi,
dTravlr: change in aperture ratio learning value,
The integral correction value Ravfbi is calculated by the following equation, and the sum of these values is calculated in step 7 as a feedback amount Avnt of the aperture ratio. Calculate as fb.
[0232]
Here, up to the second term on the right side of Equation 31 is a normal learning operation. In the present embodiment, the third term on the right side is newly added, and Ravfbi, which is the current integral correction value._n-1DTravlr, which is a change from the previous time to the current time of the aperture ratio learned value Travlr, is subtracted from + Gkvnti × Eqac (the calculation cycle of the integral correction value and the aperture ratio learned value is the same at 10 ms). The aperture ratio learned value Ravlr is updated based on the integral correction value Ravfbi, as will be described later (see steps 2 to 6 in FIG. 80). Thus, all or part of the integral correction value Ravfbi is changed to the aperture ratio learned value Ravlr. On the other hand, the total aperture ratio correction value (= Avnt) is subtracted from the integral correction value in the next cycle by the amount replaced with the aperture ratio learning value Ravlr. This is to keep fb + Travlr) constant during aperture ratio learning.
[0233]
FIG. 78 (subroutine of step 4 in FIG. 69) is for setting the learning permission flag FVNLR used for opening ratio learning. In step 1, the target EGR rate Megr, the atmospheric pressure Pa, the water temperature Tw, the control error Eqac0 (obtained from FIG. 72), and the target intake air amount delay processing value tQacd are read.
[0234]
The learning permission condition is determined by checking the contents of Steps 2 to 9 one by one. When all the items are satisfied, the opening ratio learning is permitted. When one of the items is contrary, the opening ratio learning is prohibited. To do. That is,
Step 2: In the learning area
Step 3: Feedback permission flag FVNFB = 1.
Step 4: Megr is less than or equal to a predetermined value KVNLRMEGR # (that is, the non-operating range of EGR),
Step 5: Pa is equal to or greater than a predetermined value KVNLRPA # (not highland),
Step 6: Tw is equal to or greater than a predetermined value KVNLRTW # (warming-up is completed)
Step 7: The absolute value of the ratio of Eqac0 to tQacd is equal to or smaller than a predetermined value KVNLREQA # (no disturbance is entered).
Step 8: The over boost determination flag FOVRBST = 0 and the over boost release transition flag FCLROB = 0.
Step 9: Air flow meter failure determination flag FDGMAF = 0
When all of the above are established, the learning permission flag FVNLR = 1 is set to permit the opening ratio learning in step 10; otherwise, the process proceeds to step 11 and the learning permission flag FVNLR = 0 is set to prohibit the opening ratio learning. .
[0235]
The reason why the ratio between the control error Eqac0 and the target (tQacd) is taken in step 7 is that the ratio of the control error to the target is to be constant even if the target changes. For simplicity, the absolute value of the control error may be compared with a predetermined value.
[0236]
Here, as the learning area, as shown in FIG. 79, a predetermined area is given in advance for the target fuel injection amount Qsol as the engine load and the engine speed Ne. However, FIG. 79 is only shown as a model, and is actually provided in a part of the feedback area of the aperture ratio as shown in FIG. A desirable condition for the learning region is that the sensitivity of the aperture ratio learning is good (the change in the amount of fresh air with respect to the aperture ratio is large).
[0237]
FIG. 80 (subroutine of step 5 in FIG. 69) is for calculating the aperture ratio learned value Ravlr.
[0238]
In step 1, the aperture ratio learned value Ravlr stored in the memory EEPROM (non-volatile RAM) is read and stored as Ravlrz which is the previous aperture ratio learned value, and then in step 2, the learning permission flag FVNLR is viewed. When the learning permission flag FVNLR = 1, the process proceeds to Steps 3 to 6, and the aperture ratio learning value is calculated (updated) in the same manner as the normal learning method. That is, in steps 3 and 4, the integral correction value Ravfbi as the feedback value of the opening ratio is entered into the opening ratio learning initial value Ravlr0, and learning is performed by searching a map containing, for example, FIG. 81 from the operating conditions (Ne, Qsol). The speed Kvntlrn is calculated, and the opening ratio learning initial value Ravlr0 and the learning speed Kvntlrn are used in step 5
[0239]
[Expression 32]
Ravlr = Ravlr0 × Kvntlrn + (1−Kvntlrn) × Ravlr_n-1,
Where Ravlr: the updated aperture ratio learning value,
Ravlr_n-1: Opening ratio learning value before update (= learning value read value),
And the updated aperture ratio learning value is stored in the memory EEPROM in step 6 (the updated value is overwritten on the previous value). Accordingly, for example, if the learning speed Kvntlrn is 1 at the maximum, the entire integral correction value Ravfbi is replaced with the aperture ratio learned value Ravlr, and if the learning speed Kvntlrn is less than 1, a part of the integral correction value Ravfbi is replaced.
[0240]
As shown in FIG. 81, the learning speed Kvntlrn is a value that increases as Qsol and Ne increase (however, Kvntlrn ≦ 1). This is because the larger the Qsol and Ne, the higher the sensitivity (the larger the change in the amount of fresh air with respect to the opening ratio), and the faster the opening ratio learning ends as the Qsol and Ne increase.
[0241]
On the other hand, when the learning permission flag FVNLR = 0, the learning value is outside the learning region, and the aperture ratio learning value cannot be calculated (updated).
[0242]
However, in this case, in this embodiment, Steps 7 to 10 in FIG. 80 are newly added to calculate an aperture ratio learning value for reflecting the aperture ratio learned value Ravlr obtained in the learning area outside the learning area. However, the aperture ratio learned value calculated outside the learning area also uses the same Ravlr as the aperture ratio learned value updated in the learning area as a symbol of the learning value. The area where the aperture ratio learned value for reflecting the aperture ratio learned value is calculated is an area where the learning area is excluded from the feedback ratio feedback area.
[0243]
Specifically, in step 7 of FIG. 80, Ravlr which is the previous aperture ratio learning value._n-1(Aperture ratio learning value stored in the memory EEPROM immediately before executing the processing of Step 7) is entered in the aperture ratio learning initial value Ravl0. In steps 8 and 9, for example, by searching a map having the contents shown in FIG. 82 from the operating conditions (Qsol, Ne), the operating area reflection coefficient Gkvntlnq of the opening ratio learning value and the actual opening ratio Rvnt (operation of the supercharging pressure) For example, the aperture ratio reflection coefficient Gkvntlav of the aperture ratio learning value is calculated by searching a table having the contents shown in FIG.
[0244]
[Expression 33]
Ravlr = Ravlr0 × Gkvntlnq × Gkvntlav
The aperture ratio learning value Ravlr in the reflection area is calculated by the following formula.
[0245]
Since the aperture ratio learned value obtained by Equation 33 is used only to reflect the aperture ratio learned value outside the learning area, it is stored in the memory EEPROM, unlike the aperture ratio learned value updated in the learning area. Do not do anything (no step corresponding to step 6).
[0246]
As shown in FIG. 82, the driving region reflection coefficient Gkvntlnq is a value that becomes smaller than 1 as it goes away from the learning region (maximum 1 in the learning region). This is because the learning value near the learning area can be considered to be almost the same as the learning area, but if the learning ratio is the same as the learning area even if it is far from the learning area, the true opening ratio Since the deviation from the learning value is too large and overboost may occur, the reflection coefficient is made smaller so that the deviation from the learning region is avoided.
[0247]
As shown in FIG. 83, the aperture ratio reflection coefficient Gkvntlav is a value that decreases in a region where the actual aperture ratio Rvnt is small. This is a characteristic in which the amount of fresh air with respect to the opening ratio is almost similar to the inversely proportional characteristic, and even in a region where the opening ratio is small (region where the boost pressure rises suddenly), the region where the opening ratio is large (supercharging pressure If the same aperture ratio learning value is given to the area where the rise is bad), the aperture ratio learning value is too large, and overboost may occur. Is to give.
[0248]
In step 11 of FIG. 80, from the aperture ratio learned value Ravlr thus obtained and the previous aperture ratio learned value Ravlrz.
[0249]
[Expression 34]
dTravlr = Ravlr-Ravlrz
The amount of change in the aperture ratio learned value (the amount of change per 10 ms of calculation cycle) dTravlr is calculated by the following formula. This change dTravlr is the feedback amount Avnt of the opening ratio. Used for the calculation of fb (see step 6 in FIG. 77). Therefore, in this embodiment, the total aperture ratio correction value is kept constant not only in the learning area but also in the reflection area.
[0250]
This completes the description of FIG.
[0251]
Next, FIG. 84 (subroutine of step 6 in FIG. 41) is for calculating the final command opening ratio Trvnt.
[0252]
Feed forward amount Avnt of target opening ratio in step 1 f, the feedback ratio Avnt of the aperture ratio The value obtained by reading fb and the aperture ratio learned value Ravlr and adding them in step 2 is calculated as the command aperture ratio Avnt.
[0253]
In step 3, advance processing is performed in order to compensate for the dynamics of the actuator 54. This is because when the actuator 54 is a pressure actuator, there is a response delay that cannot be ignored unlike the case of a step motor. The advance process of the actuator 54 will be described with reference to FIG.
[0254]
In FIG. 85 (subroutine of step 3 in FIG. 84), the command opening ratio Avnt (obtained in step 2 of FIG. 84) is read in step 1, and this value and the previous command opening ratio Avnt are read._n-1Is compared with a predetermined value EPSDTY #. Avnt and Avnt_n-1When the absolute value of the difference between the two is greater than or equal to the predetermined value EPSDTY # (the command opening ratio is changing), the command opening ratio clamp flag FCLPVNDTY is set to 0 in step 3, and Avnt and Avnt_n-1When the absolute value of the difference between the two becomes less than the predetermined value EPSDTY #, the process proceeds from step 2 to step 9 where the command opening ratio clamp flag FCLPVNDTY = 1.
[0255]
The clamp flag FCLPVNDTY is newly introduced in this embodiment, and is used to prohibit feedback control of the opening ratio (see FIG. 70). That is, when the clamp flag FCLPVNDTY = 1, feedback control is prohibited from the next time. It is determined that the change in the command opening ratio Avnt has converged from the clamp flag FCLPVNDTY = 1 (that is, the change in the command opening ratio Avnt has become less than a predetermined value). In this case, the opening ratio is further feedback controlled. It is not necessary.
[0256]
Step 3 After setting the clamp flag FCLPVNDTY = 0, the process proceeds to Step 4 and subsequent steps.
[0257]
In step 4, the command opening ratio Avnt and the previous command opening ratio Avnt_n-1Compare Avnt> Avnt_n-1If (the actuator 54 is moved to the opening side of the variable nozzle 53), the process proceeds to Steps 5 and 6, and the predetermined value GKVACTP # is equivalent to the actuator advance correction gain Gkact, and the predetermined value TCVACTP # is equivalent to the time constant for actuator advance correction. Set as the value Tcact, whereas Avnt <Avnt_n-1(When the actuator 54 is moved to the closing side of the variable nozzle 53), the process proceeds to Steps 7 and 8, and the predetermined value GKVACTN # is set to the actuator advance correction gain Gkact, and the predetermined value TCVACTN # is set to the actuator advance correction time constant. Set as equivalent value Tcact.
[0258]
The actuator advance correction gain Gkact and the time constant equivalent value Tcact of the actuator advance correction are made different between when the actuator 54 is moved to the open side of the variable nozzle 53 and when it is moved to the close side. # <TCVACTN #. This is because when the actuator 54 is moved to the closing side of the variable nozzle 53, it is necessary to resist the exhaust pressure, so that the gain Gkact is increased and the time constant is decreased (there is a reciprocal relationship with the time constant). This is because the time constant equivalent value Tcact needs to be increased).
[0259]
On the other hand, after setting the clamp flag FCLPVNDTY = 1 in step 9, the process proceeds to steps 10 and 11 to ensure the stability of the pressure actuator advance process, and the previous actuator advance correction gain and the time constant equivalent value of the actuator advance correction are maintained. To do.
[0260]
In step 12, the actuator advance correction time constant equivalent value Tcact and the command opening ratio Avnt thus obtained are used.
[0261]
[Expression 35]
Cvact = Avnt × Tcact + Cvact_n-1× (1-Tcact),
However, Cvact_n-1: Last Cvact,
The expected opening ratio Cvact is calculated by the following formula, and from this value and the command opening ratio Avnt, in step 13,
[0262]
[Expression 36]
Trvnt = Gkact × Avnt− (Gkact−1) × Cvact_n-1,
However, Cvact_n-1: Last Cvact,
The advance correction is performed by the following formula, and the final command opening ratio Trvnt is calculated. The advance processing itself in steps 12 and 13 is basically the same as the advance processing shown in steps 4 and 5 in FIG.
[0263]
In this way, in the flow of FIG. 85, advance processing is performed in consideration of only the response delay of the actuator 54 (advance processing in consideration of only the response delay of the turbocharger / intake / exhaust has been described in FIG. 63).
[0264]
In this way, when the final command opening ratio Trvnt, which is a value after performing the advance processing in consideration of the response delay of the actuator 54 itself, is calculated, returning to FIG. 84, in step 4, for example, FIG. 86 is obtained from this final command opening ratio Trvnt. The command opening ratio linearization processing value Ratdty is set by searching a table (linearization table) as contents.
[0265]
This linearization processing is necessary when the command signal to the actuator has non-linear characteristics with respect to the opening ratio (or opening area) as shown in FIG.
[0266]
87 (subroutine of step 7 in FIG. 41) is for setting a control command duty value Dtyvnt which is an ON duty value (hereinafter simply referred to as “duty value”) applied to the pressure control valve 56. First, at step 1, the engine speed Ne, the target fuel injection amount Qsol, the command opening ratio linearization processing value Ratdty, the time constant equivalent value Tcact of the actuator 54, and the water temperature Tw are read.
[0267]
In step 2, the duty selection signal flag is set. This flag setting will be described with reference to the flowchart of FIG. In FIG. 88, the command opening ratio Avnt and the time constant equivalent value Tcact of the actuator 54 are read in Step 1, and from these, in Step 2,
[0268]
[Expression 37]
Adlyvnt = Avnt × Tcact + Adlyvnt_n-1× (1-Tcact),
However, Adlyvnt_n-1: Previous Adlyvnt,
The expected opening ratio Adlyvnt is calculated by performing a delay process according to the following formula, and this value and Adlyvnt that is the previous value of M (where M is an integer constant) times of the previous predicted opening ratio_nMAre compared in step 3.
[0269]
Adlyvnt ≧ Adlyvnt_nMWhen it is (when it is in an increasing tendency or in a steady state), in order to indicate that it is in an increasing tendency or in a steady state, the operation direction command flag fvnt = 1 is set in step 4, otherwise the operation direction command flag fvnt = in step 5. 0. In Step 6, Adlyvnt and Adlyvnt are used to separate the case of increasing tendency from the steady state._nMAnd Adlyvnt = Adlyvnt_nMIn step S7, the duty holding flag fvnt2 = 1 is set in step 7; otherwise, the duty holding flag fvnt2 = 0 is set in step 8.
[0270]
When the setting of the two flags fvnt and fvnt2 is completed in this way, the process returns to step 3 in FIG. 87, and the temperature correction amount Dty of the duty value is returned. t is calculated. This calculation will be described with reference to the flowchart of FIG.
[0271]
In FIG. 89, the engine rotational speed Ne, the target fuel injection amount Qsol, and the water temperature Tw are read in Step 1, and the basic exhaust temperature Texhb is retrieved from Ne and Qsol by searching, for example, a map containing FIG. Is calculated. Here, Texhb is the exhaust temperature after completion of warm-up. On the other hand, if it is in the middle of warming up, it differs from the exhaust temperature after completion of warming up. Therefore, in step 3, for example, by searching a table having the contents shown in FIG. Ktexh tw is calculated, and the value obtained by multiplying this value by the basic exhaust temperature in step 4 is calculated as the exhaust temperature Texhi.
[0272]
In step 5, from this exhaust temperature Texhi
[0273]
[Formula 38]
Texhdly = Texhi × KEXH # + Texhdly_n-1× (1-KEXH #),
Where KEXH #: constant,
Texhdly_n-1: The previous Texhdly,
A value obtained by performing the delay process according to the equation is calculated as the actual exhaust temperature Texhdly. This is to perform a delay process for the thermal inertia.
[0274]
In step 6, the difference dTexh between the basic exhaust temperature Texhb and the actual exhaust temperature Texhdly is calculated, and in step 7, for example, a table having the contents shown in FIG. t is calculated. Steps 6 and 7 are maps (Duty used for hysteresis) described later. h p, Duty h n, Duty l p, Duty l In consideration of setting the map of n) after completion of warm-up, a correction amount corresponding to the difference from that state (that is, dTexh) is given. The temperature correction amount Dty The correction by t is a process required when an actuator having temperature characteristics depending on the ambient temperature is used (see FIG. 93).
[0275]
In this way, the temperature correction amount Dty When the calculation of t is completed, the process returns to step 4 in FIG.
[0276]
Steps 4 to 9 in FIG. 87 perform hysteresis processing. This process will be described in advance with reference to FIG. 98. This is because the upper characteristic (Duty) when the command opening ratio linearization process value Ratdty tends to increase. l p is the command signal when the variable nozzle is fully open, Duty h When the command opening ratio linearization processing value Ratdty tends to decrease while p is used as a command signal when p is a variable nozzle fully closed, another lower characteristic (Duty) is used. l n is the command signal when the variable nozzle is fully open, Duty hnIs used as a command signal when the variable nozzle is fully closed. Note that there is a region where the two characteristics are reversed in a region where the Ratdty is close to 1, but this region is not actually used.
[0277]
Returning to FIG. 87, in step 4, the flag fvnt1 is seen. When fvnt = 1 (that is, when the opening ratio tends to increase or is in a steady state), the process proceeds to steps 5 and 6, for example, a map (Duty) having the contents shown in FIG. h p map) and a map (Duty) containing the contents of FIG. l Duty value Duty when variable nozzle is fully closed by searching (p map) h and duty value Duty when variable nozzle is fully open Set l respectively. On the other hand, when fvnt = 0 (that is, when the opening ratio tends to decrease), the process proceeds to steps 7 and 8, for example, a map (Duty) having the contents shown in FIG. h n map) and a map (Duty) with the contents of FIG. l n map) by searching the variable nozzle fully closed duty value Duty h and duty value Duty when variable nozzle is fully open Set l respectively.
[0278]
Duty value Duty when variable nozzle is fully closed thus set h, Duty value Duty when variable nozzle is fully open In step 9, using l and the command opening ratio linearization processing value Ratdty,
[0279]
[39]
Dty h = (Duty h-Duty l) × Ratdty + Duty l + Dty t
The command duty value basic value Dty is calculated by performing linear interpolation calculation using the 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 hysteresis processing), even when the command opening ratio linearization processing value is the same, the command opening ratio linearization processing value is in a tendency of increasing (or steady state) than the command opening ratio linearization processing value is decreasing. Duty value basic value Dty h increases.
[0280]
In step 10, another flag fvnt2 is seen. When fvnt2 = 1 (that is, when 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 entered into the normal command duty value Dtyv (duty value is held), and when fvnt2 = 0 (that is, the opening ratio tends to decrease), the process proceeds to step 12, and the latest calculated value Dty Let h be Dtyv.
[0281]
In step 13, an operation confirmation control process is performed. This process will be described with reference to the flowchart of FIG. In FIG. 99, 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.
[0282]
The condition determination for entering the operation confirmation control is performed by checking the contents of steps 2, 3, 4, and 5 one by one. When all the items are satisfied, the time until the control execution is further measured. enter. That is,
Step 2: Qsol is less than a predetermined value QSOLDIZ # (that is, when fuel is cut)
Is,
Step 3: Ne is less than a predetermined value NEDIZ # (that is, a middle rotation speed range).
Step 4: Tw is less than a predetermined value TWDIZ # (that is, before completion of warm-up).
Step 5: Operation confirmation controlled flag fdiz = 0 (operation confirmation control has not been performed yet)
In step 6, the operation confirmation control counter Ctrdiz is incremented.
[0283]
In step 7, the operation check control counter is compared with predetermined values CTRDIZH # and CTRDIZL #. Here, the predetermined values CTRDIZL # and CTRDIZH # respectively define a lower limit and an upper limit of the operation check control counter. CTRDIZL # is a value of about 2 seconds, for example, and CTRDIZH # is a value of about 7 seconds, for example. Therefore, from the timing when the operation confirmation control counter coincides with CTRDIZL # which is the lower limit, the process proceeds to step 9 while the operation confirmation control counter is less than CTRDIZH # which is the upper limit, and the operation confirmation control command duty value is set. That is, CTRDIZH # -CTRDIZL # is the operation confirmation control execution time.
[0284]
The setting of the operation confirmation control command duty value will be described with reference to the flowchart of FIG. In FIG. 100, the operation check control counter Ctrdiz and the engine rotational speed Ne are read in step 1, and the control pattern Duty is retrieved in step 2 by searching a table containing, for example, FIG. 101 from Ctrdiz-CTRDIZL # (≧ 0). Set pu. This moves the variable nozzle 53 between the fully closed position and the fully open position in a short cycle.
[0285]
In step 3, the duty value Duty is obtained by searching a table having, for example, FIG. 102 from the engine speed Ne. p set ne and this Duty p In step 4, the above control pattern Duty A value obtained by multiplying pu is calculated as a control command duty value Dtyvnt. Control pattern Duty as shown in FIG. Duty value Duty multiplied by pu p ne is a value corresponding to the engine speed Ne. This assumes that the duty command value for checking 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 becomes higher as the rotation speed becomes higher. Therefore, the duty command value is increased accordingly. Further, the value is lowered on the higher rotation side so as not to be adversely affected by this control.
[0286]
Returning to FIG. 99, when the operation confirmation control counter is less than CTRDIZL # as the lower limit, the process proceeds from step 8 to step 15 to set the normal command duty value Dtyv as the control command duty value Dtyvnt.
[0287]
Further, when the operation confirmation control counter becomes equal to or higher than CTRDIZH # as the upper limit, the process proceeds from step 7 to step 10, and the previous operation confirmation control counter Ctrdiz_n-1And CTRDIZH # as the upper limit are compared. Ctrdiz_n-1If <CTRDIZH #, it is determined that the operation confirmation control counter has reached CTRDIZH # or more as the upper limit, and the operation confirmation control is terminated. Therefore, in step 11, the control command duty value Dtyvnt = 0. This is because the variable nozzle 53 is fully opened once at the end of the operation confirmation control to ensure control accuracy during normal control. In step 12, the operation confirmation control completed flag fdiz = 1 is set, and the current process is terminated. Since the flag fdiz = 1 does not allow the process to proceed to step 6 and subsequent times after the next time, the operation confirmation control is not performed twice after the engine is started.
[0288]
When the operation confirmation control counter is not immediately after the upper limit CTRDIZH # or more, the process proceeds from step 10 to step 14, and the operation confirmation control counter Ctrdiz = 0 is set in preparation for the next time, and then the process of step 15 is executed. .
[0289]
On the other hand, when Qsol is equal to or greater than the predetermined value QSOLDIZ # (not during fuel cut), when Ne is equal to or greater than the predetermined value NEDIZ # (high rotation range), Tw is equal to or greater than the predetermined value TWDIZ # (after completion of warm-up). In order to prohibit the operation confirmation control, the process proceeds from Steps 2, 3, and 4 to Step 13, and after the flag fdiz = 0, the processes of Steps 14 and 15 are executed.
[0290]
In this way, by causing the operation confirmation control to be performed when the operation of the actuator 54 is unstable, particularly at low temperatures, the movement of the variable nozzle 53 becomes smooth, and the operation of the actuator 54 can be made more reliable.
[0291]
This is the end of the description of FIG.
[0292]
Here, the operation of the two embodiments will be described.
[0293]
The target intake air amount tQac that is set according to the operating conditions also in the case of the prior application device that performs the advance processing considering the response delay of the turbocharger / intake / exhaust with respect to the target opening ratio Rvnt of the variable nozzle 53 In contrast, it is physically impossible to follow the actual intake air amount Qac without delay by feedback control, and the actuator 54 is arranged on the side where the variable nozzle 53 is closed (the side where the boost pressure rises) with respect to the change in the operation region. When the is moved, overboost occurs (see FIG. 108).
[0294]
On the other hand, according to the present embodiment, the target intake air amount delay process is a value obtained by performing a delay process corresponding to the delay of the intake system with respect to the target intake air amount tQac set according to the operating conditions. Since the value tQacd is set as the target value in the feedback control, the area portion between tQacd as the target value in the new feedback control and the actual intake air amount Qac performs the conventional feedback control on the prior application device ( 108 (see the lowermost stage in FIG. 108) (see the lowermost stage in FIG. 109), and accordingly, the integral correction value Ravfbi calculated based on the difference between tQacd and Qac does not accumulate, so the feedback gain (integral gain) The basic value Gkvnti0) can be increased. As a result, in this embodiment, overshoot does not occur, and the target value (tQacd) converges with good response (see the one-dot chain line in the lowermost stage in FIG. 109). That is, in the case of the present embodiment, the target value in the feedback control is set within a range in which the actuator 54 can operate even for a control object having both a large dead time and a response time constant. Even when the dead time such as the order and the response time constant are on the order of several seconds and the response time constant is a large control target, both the stability and response of the boost pressure control during the transition can be achieved.
[0295]
According to FIG. 103 (experimental result) showing the relationship between the engine displacement speed and the displacement [kg / s] when the load is changed and the opening ratio of the variable nozzle 53 (a plurality of values for the same rotation speed). The change in the exhaust amount with respect to the opening ratio is small at a low rotational speed, but the change in the exhaust amount increases as the rotational speed and the load increase. Further, as shown in FIG. 104, when the closing side and the opening side of the variable nozzle 53 are compared, when the exhaust amount is the same, the opening side has a slow change in the actual intake air amount Qac relative to the opening ratio. It has high sensitivity on the closed side. Accordingly, the PI gain exhaust amount correction coefficient Gkvqexh is set according to the actual exhaust amount equivalent value Tqexhd, and the PI gain opening ratio correction factor Gkvavnt is set according to the actual opening ratio Rvnt, and the integral correction gain basic value Gkvnti0 is set as the PI gain. By correcting with the displacement correction coefficient Gkvqexh and the PI gain opening ratio correction coefficient Gkvavnt (correcting the feedback gain according to the displacement and opening ratio) Feedback gain can be provided.
[0296]
Further, since the feedback control is prohibited in the low load and low flow rate region as a non-feedback region, the sensitivity of the new air amount to the change in the opening ratio (change in the command value given to the actuator 54) is small. The stability of intake air amount control (supercharging pressure control) can be improved.
[0297]
Further, in the present embodiment in which EGR control is performed in addition to supercharging pressure control, if the intake pressure and the exhaust pressure fluctuate due to control instability on the supercharger side in the EGR operating range, the EGR amount fluctuates. This also increases the NOx emission amount, but according to the present embodiment, it corresponds to the delay of the intake system with respect to the target intake air amount tQac set according to the operating condition as described above. Since the control instability on the supercharger side is avoided by performing feedback control using the target intake air amount delay processing value tQacd, which is the value subjected to the delay processing, as the target value in the feedback control, the feedback control Even if the EGR control is simultaneously performed in the region where the NOx is performed, the NOx emission amount does not deteriorate.
[0298]
In addition, the cylinder intake gas amount Qcyl and the actual exhaust amount Qexh vary due to manufacturing variations of the air flow meter 39 (means for detecting the intake air amount) and the actuator 54 (actuator for driving the variable supercharging pressure mechanism). As described above, there is a possibility that overboost may occur beyond the supercharging limit. According to this embodiment, Qcyl which is the sum of the actual intake air amount Qac and the actual EGR amount Qec and the actual exhaust amount Qexh According to the comparison result with the overboost determination intake gas amount TQcyl that changes depending on the airflow meter, it is determined that overboost occurs when Qcyl is greater than or equal to TQcyl, and that overboost does not occur when Qcyl is less than TQcyl. Due to manufacturing variations of 39 and actuator 54, etc. Generation of overboost can be reliably prevented.
[0299]
FIG. 109 is a case where Qcyl does not exceed TQcyl when the boost pressure is increased, so the case where Qcyl becomes TQcyl or more will be described with reference to FIG. . In addition, since the operation | movement and effect in this case are the same as that of 1st, 2nd embodiment, it demonstrates mainly in the case of 1st Embodiment.
[0300]
When the boost pressure is changed to a higher side according to the change in the operating conditions, a map of the basic value of the target opening ratio during normal operation while Qcyl is less than TQcyl (that is, between t1 and t2) (Fig. 56), the target opening ratio basic value Rvnt0 is calculated (steps 5 and 8 in FIG. 54), whereas the target opening ratio during normal operation is determined from the timing t2 when Qcyl becomes equal to or higher than TQcyl. Switching from the basic value map (FIG. 56) to the target opening ratio basic value map (FIG. 55) at the time of overboost suppression (steps 5 and 7 in FIG. 54), the set intake air equivalent value tQas0 and the set EGR amount equivalent Even if the value Qes0 does not substantially change before and after the map switching, the target opening ratio basic value Rvnt0 is larger after the map switching than before the switching. That is, the command duty value Dtyvnt calculated based on the target opening ratio basic value decreases stepwise at t2 which is the map switching timing (because the command duty value becomes smaller as the opening ratio increases), thereby Since the boost pressure is weakened, the occurrence of overboost is prevented (see the thick solid line in the fourth row in FIG. 112).
[0301]
In this case, the overboost is increased as the changes in the target fuel injection amount Qsol, the engine rotational speed Ne, and the actual intake air amount Qac as the engine load are larger or the deviation amount of the cylinder intake gas amount Qcyl from the determination value TQcyl is larger. Prone to occur. Therefore, the overboost suppression time TTMROB (between t2 and t3), which is a period for selecting a map for suppressing overboost, is determined when the change amounts of these three components Qsol, Ne, and Qac are small or when the cylinder intake gas amount Qcyl is determined. When matching is performed when the amount of deviation from the value TQcyl is small, the overboost suppression time is too short and overboost occurs when the amount of change between these three factors is large or when the amount of deviation of Qcyl from TQcyl is large. On the other hand, if the overboost suppression time is matched when the amount of change of these three parties is large or when the amount of deviation of Qcyl from TQcyl is large, the amount of deviation of these three parties is small or the amount of deviation of Qcyl from TQcyl is If it is small, the over boost suppression time is too long and However, according to the present embodiment, the overboost suppression time (suppresses the boost pressure as the change amounts DQSOL, DNE, DQAC and Qcyl-TQcyl per predetermined time of Qsol, Ne, and Qac increase. This period can be avoided because the period during which the data is to be transmitted is long (FIGS. 48, 49, and 50).
[0302]
In addition, in FIG. 112, if the map of the target opening ratio basic value is switched from that at the time of overboost suppression to that at the time of normal operation so as to return to normal operation at the timing of t3 when the suppression of overboost ends, this time The command duty value Dtyvnt increases stepwise. This means that the actuator 54 is quickly moved to the side where the boost pressure rises, and therefore an over boost may occur due to the operation of the actuator 54. In this case, according to the present embodiment, the target opening ratio becomes smaller with a first order delay than the timing t3 (steps 11 and 13 in FIG. 54). As a result, the command duty value Dtyvnt is slowly increased (the movement of the actuator 54 is delayed) (see the thick solid line in the fourth stage in FIG. 112). It is possible to avoid overboost associated with quickly moving the actuator 54 to the side where the pressure rises.
[0303]
In addition, since the displacement increases according to the differential pressure between the exhaust pressure and the atmospheric pressure, the displacement increases under conditions of low atmospheric pressure such as high altitudes, and the work performed by the turbocharger increases accordingly ( Overboost is likely to occur). Therefore, if the over-boost release transition time TTMRCLROB (between t3 and t4) is matched to the condition where the atmospheric pressure is not low such as a lowland, the over-boost release transition time is too short under the condition where the atmospheric pressure is low. If overboost occurs, or conversely, the overboost release transition time is matched against conditions where the atmospheric pressure is low, such as the highland, the overboost release transition time is unnecessarily too long in the lowland. According to the present embodiment in which the overboost release transition time (the period during which the movement of the actuator for driving the boost pressure variable mechanism is delayed) is set according to the atmospheric pressure Pa (FIGS. 51 and 52), Can be avoided.
[0304]
In addition, overboost is likely to occur when the exhaust amount exceeds the predetermined value. Therefore, if the overboost release transition time is matched under the condition that the exhaust amount does not exceed the predetermined value, the overboost occurs when the exhaust amount exceeds the predetermined value. Overboost occurs when the boost release transition time is too short. On the other hand, if the overboost release transition time is matched under the condition where the exhaust amount exceeds the predetermined value, the overboost release transition time when the exhaust amount does not exceed the predetermined value However, according to the present embodiment in which the overboost release transition time is set according to the actual displacement Qexh (FIGS. 51 and 53), such a situation can be avoided.
[0305]
In the embodiment, the case has been described where the actual EGR amount Qec and the actual exhaust amount Qexh are calculated. However, the actual EGR amount Qec and the actual exhaust amount Qexh may be actually detected.
[0306]
In the embodiment, the means for determining whether or not overboost occurs is a means for calculating the sum of the actual EGR amount Qec and the actual intake air amount Qac as the cylinder intake gas amount Qcyl, and overboost determination according to the actual exhaust amount Qexh Although explained in the case of means comprising means for setting the intake gas amount TQcyl (determination value) and means for judging that overboost occurs when Qcyl is greater than or equal to TQcyl, and that overboost does not occur when Qcyl is less than TQcyl. In the case of a type that employs the supercharging pressure itself, means for determining whether overboost occurs, means for setting the determination value TPa according to the actual displacement Qexh, and the actual supercharging pressure is the determination value TPa When overboost occurs at the above time, overboost occurs when the actual boost pressure is less than the judgment value TPa. It may be composed of a means for determining that no Flip.
[0307]
In the embodiment, the over-boost suppression time TTMROB has been described as being set according to DQSOL, DNE, DQAC, and Qcyl-TQcyl (see FIGS. 49 and 50), but is further set according to the actual displacement Qexh. It does not matter (at this time, the over boost suppression time is lengthened as the actual displacement Qexh increases).
[0308]
Although the embodiment has been described in the case where the operation target value of the supercharger is the target opening ratio Rvnt, the present invention is not limited to this, and the target opening area may be used.
[0309]
In the embodiment, the case where the target intake air amount tQac is calculated has been described, but the target supercharging pressure may be used instead of the target intake air amount tQac.
[0310]
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 the following is also applicable. That is, in the exhaust turbine, if the area through which the gas passes is changed, the supercharging pressure changes. Therefore, the supercharging pressure changes even if the opening ratio of the scroll and the diffuser is changed in addition to the nozzle. Since these can eventually change the geometry of the exhaust turbine, they are collectively referred to as a variable geometric turbocharger. The present invention has application to such a variable geometric turbocharger. It is also applicable to a fixed capacity turbocharger equipped with a wastegate valve. In a variable geometric turbocharger, for example, the target value of the opening area of the turbocharger or a value equivalent to the opening area is set, and the turbocharger of a certain capacity having a wastegate valve, for example, the target value of the valve opening is set It becomes the operation target value.
[0311]
In the embodiment, the case where so-called low-temperature premixed combustion is performed in which the heat generation pattern 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, It goes without saying that the invention can be applied.
[Brief description of the drawings]
FIG. 1 is a control system diagram of one embodiment.
FIG. 2 is a schematic configuration diagram of a common rail 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 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 per cylinder.
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 target intake air amount according to the first embodiment.
FIG. 16 is a flowchart for explaining calculation of a target intake air amount 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 the collector capacity;
FIG. 19 is a map characteristic diagram of a basic value corresponding to volumetric 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 operating;
FIG. 24 is a flowchart for explaining calculation of an actual EGR amount.
FIG. 25 is a flowchart for explaining calculation of two feedback correction coefficients and a learning correction coefficient in EGR control.
FIG. 26 is a flowchart for explaining setting of a feedback permission flag.
FIG. 27 is a flowchart for explaining setting of a learned value reflection permission flag;
FIG. 28 is a flowchart for explaining setting of a learning permission flag.
FIG. 29 is a flowchart for explaining calculation of an EGR amount feedback correction coefficient;
FIG. 30 is a map characteristic diagram of a correction gain of an EGR flow rate.
FIG. 31 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 32 is a flowchart for explaining calculation of an EGR flow velocity feedback correction coefficient.
FIG. 33 is a map characteristic diagram of a correction gain of an EGR flow velocity.
FIG. 34 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 35 is a table of a learning map of error ratio learning values.
FIG. 36 is a flowchart for explaining learning value update;
FIG. 37 is a map characteristic diagram of learning speed.
FIG. 38 is a flowchart for explaining calculation of an EGR flow velocity.
FIG. 39 is a map characteristic diagram of EGR flow velocity.
FIG. 40 is a flowchart for explaining calculation of an EGR valve opening area.
FIG. 41 is a flowchart for explaining calculation of a control command duty value to be given to the pressure control valve.
FIG. 42 is a flowchart for explaining the setting of an overboost determination flag.
FIG. 43 is a model diagram showing a change in an overboost determination flag when the accelerator pedal is depressed suddenly.
44 is a map characteristic diagram of an overboost determination intake gas amount. FIG.
FIG. 45 is an efficiency characteristic diagram of a turbocharger.
FIG. 46 is a flowchart for explaining the setting of an overboost release transition flag.
FIG. 47 is a waveform diagram of an overboost determination flag and an overboost release transition flag.
FIG. 48 is a flowchart for explaining calculation of an overboost suppression time.
FIG. 49 is a map characteristic diagram of a basic value of overboost control time.
FIG. 50 is a map characteristic diagram of an overboost control time correction coefficient.
FIG. 51 is a flowchart for explaining calculation of an overboost release transition time;
FIG. 52 is a table characteristic diagram of a basic value of overboost release transition time.
FIG. 53 is a table characteristic diagram of an overboost release transition time correction coefficient.
FIG. 54 is a flowchart for explaining calculation of a target opening ratio according to the first embodiment;
FIG. 55 is a map characteristic diagram of the target opening ratio when the EGR is operating and overboost is suppressed.
FIG. 56 is a map characteristic diagram of the target opening ratio in the EGR operating range and normal operation.
FIG. 57 is a map characteristic diagram of the target opening ratio when the EGR is in a non-operating range and overboost is suppressed.
FIG. 58 is a map characteristic diagram of a target opening ratio in a non-operating range of EGR and normal operation.
FIG. 59 is a flowchart for explaining calculation of a target opening ratio according to the second embodiment;
FIG. 60 is a map characteristic diagram of a target opening ratio when an EGR is operated and overboost is suppressed.
FIG. 61 is a map characteristic diagram of the target opening ratio in the EGR operating range and normal operation.
FIG. 62 is a characteristic diagram of EGR rate, fuel consumption with respect to opening area, exhaust, and intake air amount.
FIG. 63 is a flowchart for explaining calculation of a feedforward amount of a target opening ratio.
FIG. 64 is a waveform diagram showing changes in the actual exhaust flow rate equivalent value when the fuel injection amount is increased stepwise.
FIG. 65 is a table characteristic diagram of the advance correction gain when the variable nozzle is moved to the open side.
FIG. 66 is a table characteristic view of the advance correction gain when the variable nozzle is moved to the closing side.
FIG. 67 is a table characteristic diagram of time constant equivalent values for advance correction when the variable nozzle is moved to the open side.
FIG. 68 is a table characteristic diagram of a time constant equivalent value for advance correction when the variable nozzle is moved to the closing side.
FIG. 69 is a flowchart for explaining calculation of an opening ratio correction value;
FIG. 70 is a flowchart for explaining setting of a feedback permission flag.
FIG. 71 is a feedback area diagram.
FIG. 72 is a flowchart for explaining feedback gain setting;
FIG. 73 is a table characteristic diagram of a basic proportional gain basic value.
FIG. 74 is a table characteristic diagram of a basic integral gain basic value.
FIG. 75 is a table characteristic diagram of PI gain exhaust amount correction coefficients;
FIG. 76 is a table characteristic view of an aperture ratio correction coefficient for PI gain.
FIG. 77 is a flowchart for explaining calculation of an opening ratio feedback amount;
FIG. 78 is a flowchart for explaining the setting of a learning permission flag.
FIG. 79 is a learning area diagram.
FIG. 80 is a flowchart for explaining calculation of an aperture ratio learned value.
FIG. 81 is a map characteristic diagram of a learning speed.
FIG. 82 is a map characteristic diagram of an operation region reflection coefficient.
FIG. 83 is a table characteristic diagram of an opening ratio reflection coefficient.
FIG. 84 is a flowchart for explaining calculation of a final command opening ratio.
FIG. 85 is a flowchart for explaining advance processing of the actuator itself.
FIG. 86 is a table characteristic diagram of linearization.
FIG. 87 is a flowchart for explaining signal conversion;
FIG. 88 is a flowchart for explaining setting of a duty selection signal flag;
FIG. 89 is a flowchart for explaining a calculation of a temperature correction amount of a duty value.
FIG. 90 is a map characteristic diagram of a basic exhaust temperature.
FIG. 91 is a table characteristic diagram of a water temperature correction coefficient.
FIG. 92 is a table characteristic diagram of temperature correction amounts.
FIG. 93 is a temperature characteristic diagram of the actuator.
FIG. 94 is a map characteristic diagram of duty values when the variable nozzle is fully closed.
FIG. 95 is a map characteristic diagram of duty values when the variable nozzle is fully open.
FIG. 96 is a map characteristic diagram of duty values when the variable nozzle is fully closed.
FIG. 97 is a map characteristic diagram of duty values when the variable nozzle is fully open.
FIG. 98 is a hysteresis diagram when converting a command opening ratio linearization processing value into a duty value;
FIG. 99 is a flowchart for explaining operation confirmation control;
FIG. 100 is a flowchart for explaining setting of an operation check control command duty value.
FIG. 101 is a table characteristic diagram of a control pattern.
FIG. 102 is a table characteristic diagram of duty values during operation confirmation control.
FIG. 103 is a characteristic diagram showing the relationship between the displacement and the opening ratio of the variable nozzle when the engine speed and load are changed.
FIG. 104 is a characteristic diagram of the actual intake air amount when the opening ratio and the exhaust amount are changed.
105 is a more accurate characteristic diagram for FIG. 75. FIG.
FIG. 106 is a more accurate characteristic diagram with respect to FIG.
FIG. 107 is a waveform diagram for explaining the operation of the present invention while comparing it with a conventional device.
FIG. 108 is a waveform diagram for explaining the operation when normal feedback control is performed on the premise of the prior application apparatus.
FIG. 109 is a waveform diagram for explaining the operation of the first and second embodiments when the cylinder intake gas amount is less than the overboost determination intake gas amount.
FIG. 110 is a characteristic diagram illustrating a variation in the total value of the actual intake air amount and the actual EGR amount and the actual exhaust amount in the case of a type that employs an intake air amount.
FIG. 111 is a characteristic diagram showing variations in actual supercharging pressure and actual exhaust amount in the case of a type that employs supercharging pressure itself.
FIG. 112 is a waveform diagram for explaining the operation of the first and second embodiments when the cylinder intake gas amount is equal to or greater than the overboost determination intake gas amount.
FIG. 113 is a waveform diagram showing changes in the actual intake air amount when only the EGR valve opening degree changes when only the opening ratio of the variable nozzle changes.
FIG. 114 is a view corresponding to claims of the first invention.
115 is a view corresponding to claims of the second invention. FIG.
116 is a view corresponding to claims of the fourth invention. FIG.
[Explanation of symbols]
41 Control unit
52 Exhaust turbine
53 Variable nozzle
54 Actuator

Claims (12)

A turbocharger including an actuator for driving a variable supercharging pressure mechanism;
Means for setting a target intake air amount or a target boost pressure according to operating conditions;
Means for controlling the actuator so as to obtain the target intake air amount or the target boost pressure;
EGR device and
Means for detecting the actual intake air amount;
Means for calculating an actual EGR amount of the EGR device;
Means for determining whether overboost occurs based on the actual intake air amount and the actual EGR amount;
A supercharger control device comprising: means for suppressing supercharging pressure so that overboost does not occur based on the determination result. A turbocharger including an actuator for driving a variable supercharging pressure mechanism;
Means for setting a target intake air amount or a target boost pressure according to operating conditions;
Means for controlling the actuator so as to obtain the target intake air amount or the target boost pressure;
EGR device and
Means for detecting the actual intake air amount;
Means for calculating an actual EGR amount of the EGR device;
Means for calculating the actual displacement;
Means for determining whether overboost occurs based on the actual intake air amount, the actual EGR amount, and the actual exhaust amount;
A supercharger control device comprising: means for suppressing supercharging pressure so that overboost does not occur based on the determination result.   The means for determining whether or not overboost occurs is a means for calculating the sum of the actual EGR amount and the actual intake air amount as a cylinder intake gas amount, a means for setting a determination value according to the actual exhaust amount, and a cylinder intake gas 3. The apparatus according to claim 2, further comprising means for determining that overboost occurs when the amount is greater than or equal to a determination value and that no overboost occurs when the cylinder intake gas amount is less than the determination value. Supercharger control device. A turbocharger including an actuator for driving a variable supercharging pressure mechanism;
Means for setting a target intake air amount or a target boost pressure according to operating conditions;
Means for controlling the actuator so as to obtain the target intake air amount or the target boost pressure;
EGR device and
Means for calculating the actual displacement;
Means for detecting an actual supercharging pressure in an operating range of the EGR device;
Means for determining whether overboost occurs based on the actual boost pressure and the actual displacement;
A supercharger control device comprising: means for suppressing supercharging pressure so that overboost does not occur based on the determination result. The means for determining whether or not overboost occurs is a means for setting a determination value according to the actual displacement, and if overboost occurs when the actual boost pressure is equal to or greater than the determination value, the actual boost pressure is also determined by the determination value. 5. The supercharger control device according to claim 4 , further comprising means for determining that an overboost does not occur when the ratio is less than the value. The means for controlling the actuator includes means for setting an operation target value of the supercharger based on a target intake air amount or target supercharging pressure and a control target value of the EGR device, and an operation target value of the supercharger. In this case, the means for suppressing the supercharging pressure is set such that the overboost is set when the overboost occurs under the condition that the overboost occurs. The supercharger control device according to any one of claims 1 to 5 , wherein the supercharger control device is a means for switching to a value on the side where the supercharging pressure is weakened compared to a non-occurring condition. The period during which the boost pressure is suppressed so as not to cause overboost is set in accordance with a change amount per predetermined time of the engine load or a change amount per predetermined time of the engine speed. The supercharger control device according to any one of 6 to 6 .   The period for suppressing the boost pressure so as not to cause overboost is set according to the amount of change per predetermined time of the actual intake air amount. Supercharger control device.   The turbocharger according to claim 3, wherein a period during which the boost pressure is suppressed so as not to cause overboost is set according to a deviation amount of the cylinder intake gas amount from the determination value or an exhaust amount. Control device. The supercharger control device according to any one of claims 1 to 9 , wherein when the actuator is returned to a side where the boost pressure rises after suppressing the boost pressure, the movement of the actuator is delayed. . The supercharger control device according to claim 10 , wherein a period for delaying the movement of the actuator is set according to an atmospheric pressure or an exhaust amount.   The supercharger control device according to claim 3, wherein the determination value is set with a characteristic that is substantially mountain-shaped with respect to the displacement.

Images