JPH084543A - Feedback control device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] In feedback control of the supercharging pressure of the internal combustion engine, the fluctuation of the supercharging pressure is suppressed only when necessary to suppress the occurrence of the hunting phenomenon. A supercharger 21 driven by an exhaust flow is provided in an intake passage 6 and an exhaust passage 7 of an engine 1. The exhaust passage 7 is provided with a passage 24 that bypasses the supercharger 21, and the passage 24 is provided with a valve 25 driven by a negative pressure switching valve (VSV) 29 or the like for controlling the exhaust flow rate. Electronic control unit (EC
U) 50 controls the VSV 29 to match the actual boost pressure value with the target value according to the operating state,
The supercharging pressure by the supercharger 21 is controlled. The ECU 50 calculates the supercharging pressure change rate based on the detection value of the intake pressure sensor 43,
When the rate of change is large, the control cycle of the VSV 29 is set shorter than the basic cycle. Therefore, when the change in the supercharging pressure is large, the number of times the VSV 29 is controlled per predetermined time increases, and the supercharging pressure quickly converges to the target value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedback control device for an internal combustion engine, which controls an operating state quantity of the internal combustion engine to match a target state quantity.

[0002]

2. Description of the Related Art Heretofore, as a device applied to an internal combustion engine, a feedback control device has been known which controls the operating state quantity so as to match a target state quantity. For example, a feedback control of the supercharging pressure to the engine or a feedback control of the idle speed of the engine can be used.

In the supercharging pressure feedback control device, the operation of the supercharger is controlled so that the actual supercharging pressure value matches the target value according to the operating condition. Here, it is general that the difference between the actual supercharging pressure value and the target value is obtained, and the control amount of the supercharger is determined according to the difference. In this control device, during steady operation in which the engine is operated at a constant speed, the supercharging pressure follows the target value well, and the supercharging pressure control response is also good. However, during or immediately after the transient operation in which the engine is accelerated or decelerated, the difference between the actual boost pressure value and the target value becomes large, and the followability of the boost pressure to the target value tends to decrease. . Therefore, the actual supercharging pressure value may cause overshoot or undershoot with respect to the target value, and there is a possibility that the repetition of the supercharging pressure value may lead to a hunting phenomenon.

On the other hand, in the idle speed control (ISC) device, the operation of the ISC valve is controlled so that the actual engine speed value during idling matches the target value suitable for idling. Here again, the control amount of the ISC valve is generally determined according to the difference between the actual rotational speed value and the target value. Therefore, even in this control device, when the difference between the actual rotational speed value and the target value is large, the followability of the idle rotational speed with respect to the target value becomes poor, and the idle rotational speed may lead to a hunting phenomenon.

Therefore, Japanese Patent Publication No. 3-24569 proposes a "supercharging pressure control device for an engine with a supercharger" for coping with the above-mentioned problems relating to the supercharging pressure control. In this control device, in order to cope with the time delay of the feedback control of the supercharging pressure and suppress the hunting phenomenon of the supercharging pressure, the number of control times for controlling the supercharging pressure per constant time is set to be high. I try to change it a little. That is, when the engine speed is high, the control count is set to be small (the control cycle is long), and when the engine speed is low, the control count is set to be large (the control cycle is short).
Is set. By this control, the control cycle of the feedback control and the time delay of the control are made asynchronous.
In this control, the correspondence between the control cycle of the supercharging pressure feedback control and the time delay of the control changes according to the engine speed, and the supercharging pressure fluctuates in synchronization within a specific range of the engine speed. It was made paying attention to the fact that it is amplified.

[0006]

However, in the control device of the above-mentioned conventional publication, the control cycle of the feedback control (the number of control times per fixed time) is simply changed according to the magnitude of the engine speed. Therefore, when the supercharging pressure actually fluctuates greatly when the engine speed is high, the fluctuation cannot be immediately suppressed. For example,
Even when the engine speed is high, during or immediately after the acceleration or deceleration of the engine, the fluctuation of the supercharging pressure becomes large, and the overshoot of the supercharging pressure easily occurs. The control device disclosed in the conventional publication cannot cope with such a case, and an improvement is desired.

Further, even if the engine speed is low, it is not necessary to intentionally shorten the control cycle if the feedback control is stable. In this case, the control cycle is shortened and the number of times of control is increased, so that wasteful control is performed. For example, even if the engine speed is low, if the fluctuation of the engine speed is small, the fluctuation of the supercharging pressure is small and the hunting phenomenon in the supercharging pressure state is unlikely to occur. In the control device disclosed in the conventional publication, wasteful control is performed by the increase in the number of times of control in such a case, and improvement is desired.

On the other hand, the same control as that of the control device disclosed in the prior art can be applied to other feedback control including idle speed control, but the same problem as described above may occur.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is feedback control for matching the operating state quantity of an internal combustion engine with a target state quantity.
An object of the present invention is to provide a feedback control device for an internal combustion engine that can suppress the fluctuation of the operating state amount only when necessary and suppress the occurrence of the hunting phenomenon.

[0010]

In order to achieve the above object, in the first aspect of the present invention as set forth in claim 1, as shown in FIG. 1, adjustment for adjusting the operating state quantity of the internal combustion engine M1. Means M2 and operating state detecting means M3 for detecting the operating state quantity are provided, and the adjusting means M2 is provided to match the actual operating state quantity detected by the operating state detecting means M3 with the target state quantity. A feedback control device for an internal combustion engine, which is controlled by a control cycle setting means M4 for setting a control cycle so that the adjusting means M2 is controlled with a predetermined basic cycle, and an operating state detecting means M3. The change rate calculating means M5 for calculating the change rate of the actual operating state amount, and the control cycle setting means M4 set according to the change rate calculated by the change rate calculating means M5. It purports to be a control period and a control period changing means M6 for changing from the basic cycle that.

In order to achieve the above object, in the second aspect of the present invention, the control cycle changing means M6 changes the control cycle to be shorter than the basic cycle when the rate of change is large. Is intended.

[0012]

According to the first invention, as shown in FIG.
The adjusting means M2 is controlled so that the actual operating state quantity detected by the operating state detecting means M3 matches the target state quantity.

Here, the control cycle of the adjusting means M2 is set by the control cycle setting means M4 so as to be a predetermined basic cycle. At this time, the change rate calculating means M5 calculates the change rate of the actual operating state quantity. And the adjusting means M2
The control cycle is changed by the control cycle changing means M6 from the basic cycle to an appropriate cycle according to the rate of change.

Therefore, the number of times of control of the adjusting means M2 per predetermined time is increased or decreased according to the degree of change of the operating state quantity, and the state can be changed according to the state. According to the second aspect of the invention, when the rate of change of the operating state amount is large, the control cycle changing means M6 causes the adjusting means M to change.
The control cycle of 2 can be changed to be shorter than the basic cycle.

Therefore, when the degree of change in the above state is large, the number of times of control of the adjusting means M2 per predetermined time increases accordingly, and the followability of the state to the target state is accelerated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the feedback control device for an internal combustion engine according to the first and second aspects of the invention is embodied in a gasoline engine system of an automobile will be described in detail below with reference to FIGS.

FIG. 2 is a schematic configuration diagram showing a gasoline engine system of an internal combustion engine with a supercharger mounted on an automobile in this embodiment. Engine 1 has multiple cylinders 2
Is provided. A piston 3 is provided in each cylinder 2 so as to be vertically movable. The piston 3 is connected to a crank shaft (not shown), and the vertical movement of the piston 3 causes the crank shaft to rotate. In each cylinder 2, the side facing the top of the piston 3 is the combustion chamber 4
Has become. A spark plug 5 is provided in each combustion chamber 4. An intake passage 6 and an exhaust passage 7 are connected to each combustion chamber 4 through an intake port 6a and an exhaust port 7a. Intake passage 6 and exhaust passage 7
Is composed of a plurality of pipes connected to each other.
An intake valve 8 and an exhaust valve 9 for opening and closing are provided in the intake port 6a and the exhaust port 7a, respectively.
Two camshafts 10 and 11 are provided to open and close these valves 8 and 9, respectively. At one end of each camshaft 10, 11, a timing pulley 12,
13 are provided respectively. Each of the pulleys 12 and 13 is drivingly connected to a crankshaft via a timing belt 14.

Therefore, when the engine 1 is in operation, the rotational force is transmitted from the crankshaft to the camshafts 10 and 11 via the members 14, 12 and 13, respectively. Each camshaft 1
The valves 8 and 9 are opened and closed by rotating 0 and 11. The valves 8 and 9 are opened and closed at a predetermined timing in synchronization with the rotation of the crankshaft and the vertical movement of the piston 3.

An air cleaner 15 is provided on the inlet side of the intake passage 6.
Is provided. An injector 16 for injecting fuel into the intake passage 6 is provided near the intake port 6a of each cylinder 2. Each injector 16
Is a solenoid valve that is opened by energization. As we all know,
Fuel in a fuel tank (not shown) is pressure-fed to each injector 16 based on the operation of the fuel pump.

Outside air (air) is taken into the intake passage 6 through the air cleaner 15. At the same time as the intake of the air, the fuel is injected from each injector 16, so that the air-fuel mixture is sucked into the combustion chamber 4 in synchronization with the opening of the intake valve 8 in the intake stroke. The air-fuel mixture sucked into the combustion chamber 4 is exploded and burned by the operation of the spark plug 5. This combustion gives a kinetic force to the piston 3 and a rotational force to the crankshaft. And
The exhaust gas after combustion is discharged from the combustion chamber 4 to the exhaust port 7 a in synchronization with the opening of the exhaust valve 9 in the exhaust stroke, and is further discharged to the outside through the exhaust passage 7.

A throttle valve 17 which is opened and closed in conjunction with the operation of an accelerator pedal (not shown) is provided in the intake passage 6. By opening / closing the throttle valve 17, the intake amount of air into the intake passage 6, that is, the intake amount Q is adjusted. Throttle valve 1
A surge tank 18 for smoothing the intake pulsation is provided downstream of 7. On the other hand, in the middle of the exhaust passage 7, a catalytic converter 20 including a three-way catalyst 19 for purifying exhaust gas is provided.

In this embodiment, both passages 6 and 7 have
A turbocharger 21 is provided as a supercharger for supercharging the intake air in each combustion chamber 4. The turbocharger 21 includes a compressor 22 and a turbine 23, and both 22 and 23 are connected by the same shaft 21a. The compressor 22 is arranged in the intake passage 6 between the air cleaner 15 and the throttle valve 17. The turbine 23 is arranged in the exhaust passage 7 upstream of the catalytic converter 20. As is well known, in the turbocharger 21, the turbine 23 is rotated by the energy of exhaust gas. Due to this rotation, the compressor 22 is integrally rotated and the intake air is boosted (supercharged). Due to this supercharging, high-density air is sent into each combustion chamber 4, and the output of the engine 1 is increased.

The exhaust passage 7 is provided with an exhaust bypass passage 24 that connects the upstream side and the downstream side of the turbine 23. A wastegate valve 25 for opening and closing is provided in the passage 24. The valve 25 is opened and closed to control the supercharging pressure by the turbocharger 21.
A diaphragm actuator 26 is provided to drive the valve 25. The actuator 26 includes a pressure chamber 26a, and the pressure chamber 26a
A first pressure passage 27 extending from the intake passage 6 on the downstream side of the compressor 22 communicates with the. Then, when the supercharging pressure introduced into the pressure chamber 26a through the pressure passage 27 exceeds the set value, the actuator 26 operates and the wastegate valve 25 is opened. By this operation, a part of the exhaust gas that should flow into the turbine 23 is bypassed through the exhaust bypass passage 24, the output of the turbine 23 is suppressed, and the generation level of the boost pressure by the compressor 22 is suppressed. Therefore, valve 2
The supercharging pressure is controlled by controlling the opening degree of No. 5.

In order to appropriately control the opening of the wastegate valve 25, the pressure chamber 26a of the actuator 26 is controlled.
A second pressure passage 28 extending from the intake passage 6 upstream of the compressor 22 is communicated with the. The passage 28 is provided with a vacuum switching valve (VSV) 29 for opening and closing the passage 28.
The VSV 29 is duty-controlled by energization based on a duty value Duty as a control signal whose opening degree is supplied in accordance with a predetermined control cycle. And VSV2
By appropriately opening 9, the atmospheric pressure lower than the supercharging pressure is introduced into the pressure chamber 26a through the pressure passage 28. By introducing this atmospheric pressure, the pressure in the pressure chamber 26a is reduced, and the waste gate valve 25 is driven in a direction to reduce its opening. In this embodiment, the exhaust bypass passage 2
4, waste gate valve 25, actuator 26
Further, the turbocharger 21 including the VSV 29 and the like constitutes the adjusting means in the present invention.

An intercooler 30 for cooling the supercharged intake air is provided in the intake passage 6 downstream of the compressor 22. The intake air compressed by the turbocharger 21 has its temperature increased by adiabatic compression to reduce the substantial amount of air. This intercooler 30
By cooling the supercharged intake air, it is possible to prevent the reduction of the substantial air amount.

An intake bypass passage 31 is provided between the air cleaner 15 and the intake passage 6 downstream of the compressor 22.
Are communicated through. A diaphragm type air bypass valve (ABV) 32 is provided in the passage 31. A supercharging pressure acts on the ABV 32 through a third pressure passage 33 extending from the surge tank 18. When the supercharging pressure acting on the ABV 32 through the passage 33 exceeds a certain upper limit value, the ABV 32
Is opened. By this operation, a part of the intake air that should flow into the compressor 22 from the air cleaner 15 is bypassed through the intake bypass passage 31, the intake air amount Q to be supercharged by the compressor 22 is reduced, and the rise of the supercharging pressure is suppressed. .

An intake air temperature sensor 41 is provided near the air cleaner 15. The sensor 41 detects the temperature of intake air (intake air temperature) THA taken into the intake passage 6 and outputs a signal corresponding to the detected temperature. A throttle sensor 42 is provided near the throttle valve 17. In this sensor 42, the throttle valve 1
The opening degree (throttle opening degree) TA of 7 is detected, and a signal corresponding to the magnitude is output. Furthermore, the surge tank 18
An intake pressure sensor 43 is provided in the. The sensor 43 detects the intake pressure PM in the surge tank 18 and outputs a signal according to the detected value. In this embodiment, since the engine 1 is provided with the turbocharger 21, the sensor 43 detects the supercharging pressure due to the operation of the turbocharger 21. An oxygen sensor 44 is provided in the middle of the exhaust passage 7. The sensor 44 detects the oxygen concentration Ox in the exhaust gas and outputs a signal corresponding to the detected value.

The engine 1 is provided with a water temperature sensor 45. The sensor 45 detects the temperature (cooling water temperature) THW of the cooling water flowing inside the engine 1 and outputs a signal according to the magnitude thereof.

The ignition signal distributed by the distributor 34 is applied to each spark plug 5. In the distributor 34, the high voltage output from the igniter 35 is distributed to each spark plug 5 in synchronization with the rotation of the crankshaft, that is, the crank angle. The ignition timing of each spark plug 5 is determined by the high voltage output timing from the igniter 35.

The distributor 34 has a built-in rotor (not shown) connected to the camshaft 11 and rotated in synchronization with the rotation of the crankshaft. The distributor 34 is provided with a rotation speed sensor 46 and a cylinder discrimination sensor 47. In the rotation speed sensor 46, the rotation speed of the crankshaft (engine speed) N
E is detected, and a signal corresponding to its magnitude is output.
Similarly, the cylinder discrimination sensor 47 detects a reference position (crank angle reference position) GP of the crankshaft at a predetermined rate according to the rotation of the rotor, and outputs a signal corresponding to the detected position.
In this embodiment, assuming that the crankshaft makes two revolutions for a series of four strokes of the engine 1, the revolution speed sensor 46 detects the crank angle at a rate of 30 ° CA per pulse, and indicates the engine revolution speed NE. Is output as a signal. The cylinder discrimination sensor 47 has 360 pulses per pulse.
The crank angle is detected at a rate of ° CA and is output as a signal indicating the crank angle reference position GP. Therefore,
By using both signals of the engine speed NE and the crank angle reference position GP in combination, the vertical movement position of the piston 3 in each cylinder 2 can be detected.

In this embodiment, the throttle valve 1
A bypass passage 36 is provided in the intake passage 6 in the vicinity of 7. This passage 36 bypasses the throttle valve 17 and connects the downstream side of the valve 17 and the downstream side of the air cleaner 15. A linear solenoid type idle speed control valve (ISCV) 37 is provided in the passage 36. This ISCV37
When the engine 1 is idling when the throttle valve 17 is fully closed, the opening degree of is duty controlled in order to stabilize the idling. By this control, the amount of air flowing through the bypass passage 36 is adjusted, the amount of intake air taken into the combustion chamber 4 during idling is controlled, and the engine speed NE during idling is adjusted.

As shown in FIG. 2, each injector 16,
The VSV 29, the igniter 35, and the ISCV 37 are drive-controlled by an electronic control unit (hereinafter simply referred to as “ECU”) 50. In this embodiment, the ECU 50 constitutes the control cycle setting means, the change rate calculating means, and the control cycle changing means of the present invention. Signals detected by the various sensors 41 to 47 and the like are input to the ECU 50. Then, the ECU 50 determines each member 1 based on each detection signal.
The drive control of 6, 29, 35 and 37 is preferably performed. In this embodiment, the throttle sensor 42, the intake pressure sensor 43, the rotation speed sensor 46 and the like constitute the operating condition detecting means in the present invention.

Next, the electrical configuration of the ECU 50 will be described with reference to the block diagram of FIG. ECU5
0 is a central processing unit (CP with a counter function.
U) 51, read only memory (ROM) 52, random access memory (RAM) 53, backup RAM
54 and the like are provided. The CPU 51 executes calculations and the like.
A predetermined control program and the like are stored in the ROM 52 in advance. The RAM 53 temporarily stores the calculation result of the CPU 51 and the like. The backup RAM 54 stores the stored data. Then, the ECU 50 uses these members 51 to 5
4 and an external input circuit 5 including an analog / digital converter
5 and the external output circuit 56 and the like are connected by a bus 57 as a logical operation circuit.

The above-mentioned sensors 41 to 47 are connected to the external input circuit 55, respectively. The members 16, 29, 35, 37 described above are connected to the external output circuit 56, respectively. Then, the CPU 51 reads the detection signals of the sensors 41 to 47 and the like input via the external input circuit 55 as input values. Based on these input values, the CPU 51 suitably controls each member 16, 29, 35, 37, etc. in order to execute fuel injection amount control, ignition timing control, idle speed control, boost pressure control, etc., respectively. . Here, the fuel injection amount control means each injector 16
By controlling the valve opening period of, the fuel injection amount injected from each injector 16 is controlled. Idle speed control means ISCV when the engine 1 is idle.
By controlling 37, the value of the engine speed NE is controlled to match a predetermined target value.
On the other hand, the supercharging pressure control is to appropriately control the opening degree of the waste gate valve 25 via the actuator 26 by duty-controlling the opening degree of the VSV 29. In particular, in this embodiment, as the supercharging pressure control, the supercharging pressure feedback control that matches the actual supercharging pressure value with the target value determined according to the operating state of the engine 1 is performed.

Next, of the various controls executed by the ECU 50, the processing contents of the boost pressure control will be described. The flowchart shown in FIG. 4 is a “target boost pressure setting routine” executed by the ECU 50 to set a target value of the boost pressure (target boost pressure NPa) according to the operating state of the engine 1. The processing of this routine is executed by a regular interrupt every predetermined time.

When the processing shifts to this routine, in step 110, based on the detection values of the sensors 42, 43, 47, etc., the input values relating to the throttle opening TA, the intake pressure PM, the engine speed NE, etc., are respectively inputted. Read.

Next, at step 120, the value of the target supercharging pressure NPa corresponding to the operating state of the engine 1 at that time is calculated based on the read input values for the respective parameters TA, PM, NE, and thereafter. The process of is once ended. In this embodiment, the above "target boost pressure setting routine"
The ECU 50 that executes the process of (1) corresponds to the target supercharging pressure setting means.

Therefore, according to the processing of this routine, during steady operation in which the engine 1 is operated at a constant speed,
During transient operation such as deceleration, depending on those conditions,
At that time, the value of the target supercharging pressure NPa that should be obtained by the turbocharger 21 is obtained.

The flowchart shown in FIG. 6 is a "V" executed by the ECU 50 using the above-mentioned target boost pressure NPa.
SV control routine ”. When the processing shifts to this routine, at step 200, each sensor 42, 4
Various parameters TA, P based on the detected values of 3, 47, etc.
Each input value related to M, NE, etc. is read. At the same time, the value of the target supercharging pressure NPa is read.

Subsequently, in step 210, it is determined whether or not the condition for feedback control is satisfied. Here, when the throttle opening TA is equal to or larger than a predetermined value and the engine speed NE is equal to or larger than a predetermined value at the same time, it is determined that the condition for the feedback control is satisfied. In this embodiment, step 21
The ECU 50 that executes the process of 0 corresponds to the condition determination means for determining the condition of the feedback control. Then, in step 210, if the condition of the feedback control is not satisfied, step 2 is performed as it is.
Move to 70. If the feedback control condition is satisfied, the process proceeds to step 220.

At step 220, the difference between the value of the target supercharging pressure NPa read in the current control cycle and the value of the actual intake pressure PM is calculated, and the calculation result is calculated as the supercharging pressure deviation Δ.
Set as Pa. In this example, step 220.
The ECU 50 that executes the processing of (1) corresponds to the supercharging pressure deviation calculating means.

Next, at step 230, the difference between the value of the intake pressure PM read in the current control cycle and the value of the intake pressure PM0 read in the previous control cycle is obtained, and the difference is changed in supercharging pressure. Set as the rate ΔPM. The supercharging pressure change rate ΔPM indicates the amount of change in the intake pressure PM per unit time, the magnitude of its absolute value indicates the magnitude of the supercharging pressure change, and the positive / negative sign indicates the direction of change. There is. That is,
When the intake pressure PM rises, it shows a positive value (+), and when the intake pressure PM falls, it shows a negative value (-). In this embodiment, the ECU 5 that executes the process of step 230
0 corresponds to the change rate calculating means in the present invention.

Next, at step 240, the correction coefficient K for the control cycle of the VSV 29 is calculated based on the value of the supercharging pressure change rate ΔPM and the value of the supercharging pressure deviation ΔPa obtained in the current control cycle. This correction coefficient K is calculated as shown in FIG.
It is performed by referring to a predetermined map as shown in FIG. In this map, the value of the correction coefficient K is the supercharging pressure change rate Δ.
It is set according to the absolute value of the PM and the supercharging pressure deviation ΔPa and the sign thereof. In this embodiment, the ECU 50 that executes the process of step 240 corresponds to the correction coefficient calculation means for calculating the correction coefficient K for correcting the control cycle.

The characteristics of this map are the supercharging pressure change rate ΔPM.
Is a relatively small positive value or a negative value, the value of the correction coefficient K changes from “1” to “0” as the supercharging pressure deviation ΔPa increases with a positive value or a negative value. It is set to gradually decrease in the range of "0.7". That is, when the supercharging pressure change rate ΔPM is small, the value of the correction coefficient K is set in the range of “1” to “0.7” according to the degree and the direction of change. The correction coefficient K is for correcting a control cycle described later regarding the control of the VSV 29. According to the correction coefficient K set as described above, the control cycle is corrected to be about three quarters of the normal basic cycle Tb.

On the other hand, when the supercharging pressure change rate ΔPM is a relatively large positive value or negative value, the supercharging pressure deviation ΔPa
As the value increases with a positive or negative value, the correction coefficient K
Is set to gradually decrease in the range of "0.5" to "0.2". That is, the supercharging pressure change rate ΔPM
Is large, the value of the correction coefficient K is set in the range of "0.5" to "0.2" according to the degree and the direction of change. According to the correction coefficient K set as described above, the control cycle is corrected to be about one quarter of the normal basic cycle Tb. That is, according to this map, the control cycle is the basic cycle T when the absolute value of the supercharging pressure change rate ΔPM is large.
It is set to be shorter than b.

In step 250, the basic cycle Tb relating to the control cycle for controlling the VSV 29 is calculated based on the value of the engine speed NE. This basic period Tb
Is obtained by referring to a predetermined map (not shown). In this map, the basic cycle Tb is set to be relatively long when the engine speed NE is large and relatively short when the engine speed NE is small. In this embodiment, E which executes the processing of this step 260
The CU 50 corresponds to the control cycle setting means in the present invention.

Next, at step 260, the basic cycle Tb found in the current control cycle is multiplied by the correction coefficient K found this time to obtain the final set cycle T.
To calculate. The set cycle T is the duty value D described above.
The periodic timing for controlling the VSV 29 is determined based on the duty. The length of this setting cycle T is determined according to the characteristics of the map shown in FIG. In this embodiment, the ECU 50 that executes the process of step 260 corresponds to the control cycle changing means in the present invention.

Then, in step 270, it is judged whether or not the cumulative value CT of the counter is equal to or larger than the value of the set cycle T obtained in the current control cycle. This cumulative value CT
Is counted by a separate "counting routine" as shown in FIG. In this embodiment, the ECU 50 that executes the process of step 270 corresponds to the control cycle time measuring means.

That is, this routine is executed at intervals of a predetermined time (for example, "4 ms"), and at step 410, it is determined whether or not the value of the cumulative value CT up to this time is the upper limit value CTmax or more. To judge. Cumulative value CT
Is less than the upper limit value CTmax, step 42
At 0, the cumulative value CT is incremented by "1" and the subsequent processing is temporarily terminated. The cumulative value CT is the upper limit value C
If it is greater than or equal to Tmax, the subsequent processing is temporarily terminated. Therefore, in step 270, the cumulative value CT counted as described above is compared with the value of the set period T. In this embodiment, the ECU 50 that executes the process of step 270 corresponds to the control cycle time measuring means for measuring the control cycle.

Here, in step 270, when the cumulative value CT is equal to or larger than the value of the set period T, step 2
At 80, the duty value Duty obtained up to the previous control cycle is updated as a new duty value Dutya. Then, in step 290, the opening degree of the VSV 29 is controlled based on the duty value Dutya, so that the feedback control is executed at the timing of this control cycle. In this embodiment, the ECU 50 that executes the processing of steps 280 and 290 corresponds to the drive control means for driving and controlling the VSV 29 based on the duty value Dutya.

Further, in step 300, the cumulative value C
After resetting T to “0”, the process proceeds to step 310. On the other hand, when the cumulative value CT is not equal to or larger than the value of the set period T in step 270, the step 31 is performed as it is.
Move to 0.

Then, step 270 or step 30
In step 310 after shifting from 0, VSV29
A duty value Duty for controlling is calculated. Detailed contents of this calculation will be described with reference to the flowchart shown in FIG.

First, at step 311, similarly to step 210 described above, it is determined whether or not the condition for feedback control is satisfied. In this embodiment, the ECU 50 that executes the processing of step 311 corresponds to the feedback control condition determination means. Then, in step 311, if the condition of the feedback control is not satisfied, the process proceeds to step 312. When the condition for feedback control is satisfied,
Control goes to step 313.

In step 312, a duty value Duty that is uniquely determined in advance for the value of the engine speed NE is calculated, and the subsequent processing is temporarily terminated.
On the other hand, in step 313, the difference between the value of the target supercharging pressure NPa and the actual value of the intake pressure PM is calculated, and the calculation result is set as the supercharging pressure deviation ΔPa. In this embodiment, the ECU 50 that executes the process of step 313 corresponds to the supercharging pressure deviation calculating means.

Subsequently, in step 314, it is determined whether or not the supercharging pressure deviation ΔPa is greater than or equal to a predetermined value A. Here, if the supercharging pressure deviation ΔPa is greater than or equal to the predetermined value A, the process proceeds to step 315.

Then, in step 315, the current duty value Duty is added to the multiplication result of the current duty value Duty and the value of the supercharging pressure deviation ΔPa, and the addition result is set as a new duty value Duty. ,
The subsequent processing is once ended. In this embodiment, the ECU 50 that executes the process of step 315 corresponds to the first calculation means for calculating the control value for the feedback control.

On the other hand, if the supercharging pressure deviation ΔPa is not equal to or larger than the predetermined value A in step 314, step 31
Go to 6. Then, in step 316, it is determined whether or not the supercharging pressure deviation ΔPa is less than the predetermined value B. The predetermined value B sets a predetermined range together with the predetermined value A, and between the two values A and B, the change of the control value for the feedback control is prohibited. here,
When the supercharging pressure deviation ΔPa is not less than the predetermined value B, the process proceeds to step 317. Then, in step 317, the current duty value Duty is set as a new duty value Duty, and the subsequent processing is temporarily terminated. When the supercharging pressure deviation ΔPa is less than the predetermined value B,
Go to step 318.

In step 318, the current duty value Duty is multiplied by the value of the boost pressure deviation ΔPa, and the multiplication result is subtracted from the current duty value Duty.
The subtraction result is set as a new duty value Duty, and the subsequent processing is temporarily terminated. In this example,
The ECU 50 that executes the process of step 318 corresponds to the second calculation means for calculating the control value for the feedback control. In this way, the duty value Dut
y is calculated. In this embodiment, the ECU 50 that executes the process of step 310 corresponds to the control value calculating means for calculating the control value for the feedback control.

As described above, the VSV 29 is controlled based on the duty value Duty in accordance with the control cycle according to the change of the intake pressure PM (supercharging pressure) at each time, and the supercharging pressure is controlled.

As described above, according to the control device of this embodiment, various parameters T when the engine 1 is operating.
Based on the values of A, PM, NE, etc., the value of the target supercharging pressure NPa corresponding to the operating state of the engine 1 is obtained. Furthermore, based on the value of the target supercharging pressure NPa and the value of the intake pressure PM corresponding to the actual supercharging pressure, the duty value Duty (Duty
a) is required. Then, particularly when the boost pressure feedback condition is satisfied, the obtained duty value D
By controlling the VSV 29 based on the duty, the actuator 26 operates and the waste gate valve 2
The opening degree of 5 is adjusted, and the flow rate of exhaust gas flowing to the turbine 23 is adjusted. As a result, feedback control is performed so that the actual boost pressure value obtained by the turbocharger 21 matches the target boost pressure NPa according to the operating state of the engine 1.

Here, according to the control device of this embodiment,
The difference between the value of the actual intake pressure PM and the value of the target supercharging pressure NPa,
That is, the duty value Dut is changed according to the value of the boost pressure deviation ΔPa.
y is required. Therefore, the duty value Duty is calculated as a value that reduces the change in the supercharging pressure when the engine 1 is in the steady operation state, and is large when the engine 1 is in the transient operating state. Is calculated as a value that Such calculation of the duty value Duty is basically performed as feedback control of the supercharging pressure.

The supercharging pressure control of this embodiment is different from the conventional control in that the control cycle of the VSV 29 controlled based on the duty value Duty is the supercharging pressure change rate ΔPM at that time.
It is subject to change. Specifically, the basic cycle Tb is set according to the magnitude of the engine speed NE at each time. Further, the change rate of the intake pressure PM at each time is obtained as the supercharging pressure change rate ΔPM, and the supercharging pressure change rate ΔP.
The correction coefficient K is obtained based on M. Then, the basic cycle Tb is corrected based on the correction coefficient K to obtain the set cycle T, and the VSV 29 is controlled based on the duty value Duty with the set cycle T as the control cycle. Here, the correction coefficient K reflects the magnitude of the supercharging pressure change rate ΔPM and the direction of its change.
When the absolute value of PM is large, the control cycle is the basic cycle T
It is set to be shorter than b.

For example, even when the engine speed NE is high, when the supercharging pressure fluctuates greatly during acceleration or deceleration of the engine 1 or immediately after that, the magnitude of the supercharging pressure change rate ΔPM is set. Accordingly, the control cycle of the VSV 29 is set shorter than the basic cycle Tb. On the other hand, even if the engine speed NE is low, if the feedback control is stable and the fluctuation of the boost pressure is small, the control cycle of the VSV 29 should be set shorter than necessary than the basic cycle Tb. There is no.

Therefore, in this embodiment, since the basic cycle Tb of the control cycle is set according to the magnitude of the engine speed NE, the time delay of the feedback control of the supercharging pressure is dealt with as in the conventional example. As a result, the hunting phenomenon of boost pressure can be suppressed.

In addition, in this embodiment, the number of times the VSV 29 is controlled per predetermined time is increased / decreased according to the degree of change in the state of the supercharging pressure change rate ΔPM. It is possible to suppress the fluctuation. Particularly, when the rate of change in supercharging pressure ΔPM is large, the number of times the VSV 29 is controlled per predetermined time increases accordingly, so that the followability of the actual supercharging pressure to the value of the target supercharging pressure NPa is accelerated. As a result, in the feedback control of the boost pressure, the control cycle is set to the basic cycle Tb only when necessary.
By making the length shorter than this, the fluctuation of the supercharging pressure can be suppressed, and the occurrence of the hunting phenomenon related to the state of the supercharging pressure can be suppressed. Further, in this embodiment, the control cycle is shortened only when necessary, so that the control frequency of the VSV 29 is not unnecessarily increased when the supercharging pressure state is stable, which is wasteful. There is no control.

Further, in this embodiment, a new duty value Duty is obtained for each control cycle set at that time. In that sense as well, the followability of the supercharging pressure with respect to the value of the target supercharging pressure NPa can be accelerated, the fluctuation of the supercharging pressure can be stabilized early, and the responsiveness and the followability of the feedback control of the supercharging pressure can be improved. It can be further increased.

An example of the result of the above boost pressure control will be described with reference to the time chart shown in FIG. This time chart shows the intake pressure PM (supercharging pressure), the duty value Duty, and the cumulative value C of the counter.
The relationship of T is shown. In this time chart, regarding the intake pressure PM and the duty value Duty, those according to the present embodiment are shown by solid lines, and those of the conventional example in which only feedback control is simply performed are shown by two-dot chain lines.
In this time chart, the intake pressure PM is the target boost pressure NP
A case is shown where the value changes from rising to falling based on the value of a.

In the control of the conventional example, the duty value Du obtained at each time is set at each time t1, t3, t6, t7, t9, t12 with a predetermined basic cycle Tb.
It is performed based on ty. On the other hand, in the control of the present embodiment, each time t1 to t6, t when the cumulative value CT of the counter reaches the value of the set cycle T at that time regardless of the basic cycle Tb.
The timing is 8 to t12, and it is performed based on the duty value Duty obtained at each time. In this embodiment, the basic period Tb is changed according to the magnitude of the supercharging pressure change rate ΔPM.
A set cycle T shorter than the set cycle T is set, and the VSV 29 is set based on the duty value Duty obtained for each set cycle T.
Is controlled. Therefore, it can be seen that the overshoot and undershoot of the intake pressure PM (supercharging pressure) with respect to the target supercharging pressure NPa are suppressed to be smaller than those in the conventional example. This effect is the same in the subsequent fluctuation of the supercharging pressure, and the supercharging pressure converges to the value of the target supercharging pressure NPa in a short time, and as a result, the hunting phenomenon of the supercharging pressure is suppressed. It can be easily understood that the boost pressure stabilizes early. The present invention can be embodied in the following other embodiments. Also in the following other embodiments, the same actions and effects as the above-mentioned embodiments can be obtained.

(1) The above embodiment has been embodied in the case where the boost pressure state of the engine 1 is feedback-controlled as the operation of the internal combustion engine or the element related to the operation. In contrast,
It can also be embodied in the case where the idle speed of the engine 1 is feedback-controlled. That is, in order to match the engine speed NE during idling with the target value, the adjusting means is adjusted according to the rate of change of the engine speed NE (speed change rate ΔNE) calculated based on the detection value of the speed sensor 46. The control cycle of the ISCV 37 is changed from the basic cycle. Also in this case, the fluctuation of the idle speed can be suppressed only when necessary, and the occurrence of the hunting phenomenon can be suppressed.

In addition to this, the present invention can be embodied with the same effect in the feedback control related to the internal combustion engine. (2) In the above embodiment, the basic cycle Tb related to the control cycle is determined based on the magnitude of the engine speed NE. On the other hand, the basic cycle relating to the control cycle may be set to a constant value.

(3) In the above embodiment, the waste gate valve 25 provided in the exhaust bypass passage 24 is set to VSV.
The supercharge pressure by the turbocharger 21 is adjusted by opening and closing by the actuator 26 operated by 29.

On the other hand, the boost pressure by the turbocharger 21 may be adjusted by opening and closing the valve provided in the exhaust bypass passage 24 with a step motor.

Although the respective embodiments of the present invention have been described above, it should be noted that the respective embodiments include the following various embodiments relating to the technical idea described in the scope of claims. It describes with those effects.

(A) In the invention described in claim 1 or 2, the adjusting means is a supercharger for supercharging the intake air of the internal combustion engine, and the operating state detecting means detects the supercharging pressure. And a feedback control device for an internal combustion engine, which is configured to control the supercharger so as to match an actual supercharging pressure value detected by the pressure detecting means with a target value. Control cycle setting means for setting a control cycle so that the supercharger is controlled with a predetermined basic cycle, and a change rate for calculating a change rate of the actual supercharging pressure detected by the pressure detecting means. An internal combustion engine including a calculating means and a control cycle changing means for changing the control cycle set by the control cycle setting means from the basic cycle according to the supercharging pressure change rate calculated by the change rate calculating means. Of the feedback control device.

According to this structure, in the feedback control for matching the state of the supercharging pressure of the internal combustion engine with the target state quantity, the fluctuation of the state of the supercharging pressure is suppressed only when necessary and the occurrence of the hunting phenomenon is suppressed. be able to.

(B) In the invention according to claim 1 or 2, the adjusting means is an intake adjusting valve for adjusting intake air during idle operation of the internal combustion engine, and the operating state detecting means is the internal combustion engine. A feedback control device for an internal combustion engine, which is rotation speed detecting means for detecting a rotation speed, and controls the intake control valve so that an actual rotation value detected by the rotation speed detecting means matches a target value. A control cycle setting means for setting a control cycle so that the intake control valve is controlled with a predetermined basic cycle, and a change rate of the actual rotation speed detected by the rotation speed detection means are calculated. And a control cycle set by the control cycle setting means according to the rotational speed change rate calculated by the change rate calculation means. The internal combustion engine of a feedback controller having a control period changing means for.

According to this structure, in the feedback control in which the state of the rotational speed during the idle operation of the internal combustion engine is matched with the target state quantity, the fluctuation of the state of the rotational speed is suppressed only when necessary, and the hunting phenomenon occurs. Can be suppressed.

In this specification, means and members relating to the constitution of the invention are defined as follows. (A) The operating state quantity of the internal combustion engine means the state quantity of the rotational speed and the output state quantity of the internal combustion engine, and further, the state quantity of the intake air to the internal combustion engine (including the supercharging pressure and the intake air quantity) and Exhaust state quantity (including exhaust pressure and exhaust volume).

(B) The supercharger is a device for increasing the output of the internal combustion engine by raising the pressure of the intake air to atmospheric pressure or higher and supplying high density air into the combustion chamber.
The structure is composed of a compressor (compressor) for compressing intake air, and a drive unit and a bearing unit of the compressor. This supercharger is divided into a "mechanical supercharger" mainly driven by the power of the engine itself and an "exhaust turbine supercharger" driven by the power of the exhaust turbine depending on the drive system of the compressor. . Further, the supercharger is divided into a “centrifugal supercharger”, an “axial flow supercharger”, and a “volumetric supercharger” from the structural viewpoint.

(C) The control cycle means the time required between the previous control and the current control when the adjusting means is controlled cyclically.

[0081]

As described in detail above, according to the first aspect of the present invention, in the feedback control for matching the operating state quantity of the internal combustion engine with the target state quantity, the control cycle of the adjusting means is actually set. The basic cycle is changed according to the change rate of the operating state quantity.

Therefore, the control frequency of the adjusting means per predetermined time is increased / decreased according to the degree of change in the above state, and the state can be changed according to the state. As a result, it is possible to suppress the fluctuation of the operating state quantity only when necessary and to suppress the occurrence of the hunting phenomenon.

According to the second aspect of the present invention, the control cycle is changed to be shorter than the basic cycle when the change rate is large. Therefore, when the change in the above state is large, the number of times of control of the adjusting means per predetermined time increases accordingly, and the followability of the state to the target state is accelerated. As a result, it is possible to suppress the fluctuation of the operating state quantity only when necessary and to suppress the occurrence of the hunting phenomenon.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram showing a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing a gasoline engine system including an internal combustion engine with a supercharger in one embodiment embodying the present invention.

FIG. 3 is a block diagram showing a configuration of an ECU and the like in one embodiment.

FIG. 4 is a flowchart showing a “target supercharging pressure setting routine” executed by the ECU in one embodiment.

FIG. 5 is a map showing a relationship of a correction coefficient (K) with respect to a supercharging pressure deviation (ΔPa) and a supercharging pressure change rate (ΔPM) in one embodiment.

FIG. 6 is a flowchart showing a “VSV control routine” executed by the ECU in the embodiment.

FIG. 7 is a flowchart showing a “count routine” executed by the ECU in the embodiment.

FIG. 8 is a flowchart showing a part of the flowchart of FIG. 6 in detail according to an embodiment.

FIG. 9 shows a cumulative value (C
4 is a time chart showing changes in T), duty value (Duty), and supercharging pressure (intake pressure (PM)).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 21 ... Turbocharger, 24 ... Exhaust bypass passage, 25 ... Wastegate valve, 26 ... Actuator, 29 ... VSV (21,
24 to 26, 29 etc. constitute an adjusting means), 37 ... ISCV as adjusting means, 42 ... Throttle sensor, 43 ... Intake pressure sensor, 47 ... Rotation speed sensor (42, 43, 47 etc.) Detection means), 50 ... ECU (50 constitutes control cycle setting means, change rate calculation means, and control cycle changing means).

Claims (2)

[Claims] 1. An actual operating state detected by the operating state detecting means, comprising: adjusting means for adjusting the operating state quantity of the internal combustion engine; and operating state detecting means for detecting the operating state quantity. A feedback control device for an internal combustion engine, which controls the adjusting means so that the amount matches a target state amount, for setting a control cycle so that the adjusting means is controlled with a predetermined basic cycle. Control cycle setting means, change rate calculating means for calculating the change rate of the actual operating state amount detected by the operating state detecting means, and the change rate calculating means according to the change rate calculated by the changing rate calculating means. A feedback control device for an internal combustion engine, comprising: a control cycle changing means for changing the control cycle set by the control cycle setting means from the basic cycle. 2. The feedback control device for an internal combustion engine according to claim 1, wherein the control cycle changing means changes the control cycle to be shorter than the basic cycle when the rate of change is large. And a feedback control device for an internal combustion engine.