JPH01240736A - Supercharged pressure control method in internal combustion engine - Google Patents

Abstract

PURPOSE:To make the shift to feed back control smooth and rapid by starting feed back control a prescribed time after a supercharged pressure getting beyond a prescribed value in a transmission stage of the supercharged pressure. CONSTITUTION:The movable vane of a turbocharger 4 is driven by an actuator 17 and an electromagnetic control valve 18 for supercharged pressure introduction to the actuator 17 is duty-controlled. When the absolute pressure in an intake pipe is less than a prescribed value, the movable vane is set to the minimum opening. When the absolute pressure in the intake pipe is beyond the feed back control starting pressure, the feed back control is started after the elapse of a prescribed time. Thus, the abnormal raise up of supercharged pressure can be prevented even in a transition stage and the shift to the feed back control can be carried out smoothly and rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling the boost pressure of an internal combustion engine, and in particular to a method for controlling boost pressure in an internal combustion engine, and in particular for controlling supercharging from a transient state to a steady state accompanied by a sudden change in boost pressure. The present invention relates to a method for controlling the boost pressure of an internal combustion engine that enables stable and appropriate pressure control. (Prior Art and Problems to be Solved by the Invention) In a supercharged internal combustion engine that uses an exhaust gas flow as a turbine drive source and is capable of controlling the boost pressure of a so-called variable displacement turbocharger, an appropriate actuator ( Feedback control is used when the boost pressure is controlled by a pressure-responsive actuation system including a diaphragm using boost pressure or negative pressure in the intake pipe as the operating pressure, or an actuation system using a step motor, etc.).

This is because supercharging pressure is affected by individual differences such as variations in manufacturing of the actuator and the components of the supercharger body, and changes over time such as deterioration of durability due to use. When controlling the boost pressure to a desired value, operating with a preset control amount will result in a large change in the boost pressure (even if the same control claw is applied, the actuator that should normally operate in response to it) In some cases, the adjustment operation amount of the operation control system (such as This is because this problem can be easily resolved. In other words, feedback control detects the deviation between the target boost pressure and the actual boost pressure and determines the control amount according to the deviation so that the deviation becomes zero. Even if there are variations in the measurements of the actuators, or even if there are changes over time, these effects will be absorbed and corrected in this control.

Therefore, when controlling the boost pressure to the required target pressure corresponding to the engine operating state, the boost pressure should be at the r1 standard pressure.
Although it is desirable to perform feedback control 1 that determines the control amount based on the deviation and controls the boost pressure to maintain the target pressure, on the other hand, in some cases, feedback control This may cause undesirable abnormalities such as -+1ζ' J2 rise.

In other words, in a so-called transient state, such as when the boost pressure suddenly increases, the control amount cannot follow the boost pressure adjustment due to the response delay of the first control system, and the boost pressure abnormality -1- field occurs. , when phenomena such as abnormal descent, hunting, etc. occur, and it is necessary to suddenly increase the boost pressure to increase engine output in response to acceleration, the target overflow that is set high according to the operating condition is When boost pressure increases toward supply pressure,
The boost pressure overshoots its target boost pressure,
The larger the overshoot, the longer the hunting period becomes and the more unstable the boost pressure control becomes.
If overboost occurs due to transient overshoot, knocking or the like occurs, which also impairs drivability during acceleration.

Therefore, in order to eliminate the above-mentioned problems with feedback control in a transient state, the applicant has developed an open loop (1) 1υ
ν, and proposed a supercharging pressure control method that performs feedback control in the steady state width (Japanese Patent Application No. 61-2).
No. 75783), it is possible to perform more stable supercharging pressure control than the previous one.

However, when each control is used differently for transient states and steady states, as in the control method proposed in -1;, there is room for improvement in the following points, and if these are also revised, it will be even more effective. It is expected that stable boost pressure control performance will be obtained.

In other words, when shifting to feedback control, if the judgment is made only by looking at the state of supercharging pressure, for example, when the supercharging pressure increases, if the supercharging pressure exceeds a predetermined value that is slightly smaller than the 11 standard supercharging river. 1- is detected, and based on this detection, it is determined that it is a steady state and feedback control is started, the boost pressure reaches the t distribution predetermined value, that is, the feedback start pressure, and then reaches the 11 standard boost pressure. A transient state exists during this period, and therefore, depending on the operating state, abnormal boost pressure sealing or hunting may occur. On the other hand, in order to avoid this, if the target boost pressure and the feedback start pressure are set quite close to each other, the boost pressure will reach a steady state before reaching the feedback start pressure, and the boost pressure control will remain open-loop control. This may happen.

It takes a while now.

As a result of the open-loop control, it is not possible to correct for variations among individual chikutuators used, changes over time, etc. by feedback control as described above.

The present invention focuses on the above-mentioned points, and the supercharging pressure suddenly increases.
- An abnormality in the boost pressure even when the pressure rises] 1. While preventing the occurrence of a rise or hunting, a reliable transition to feedback control is made possible, and the supercharging is brought from a transient state to a steady state. It is an object of the present invention to provide a method for controlling the boost pressure of an internal combustion engine that can further stabilize and optimize the pressure.

(Means for Solving the Problems) In order to achieve the above-mentioned purpose, Kippatsu 1q1 determines a controlled amount according to the deviation between the actual boost pressure and the target boost pressure, and determines the above-mentioned control amount based on the controlled amount. In a method for controlling boost pressure of an internal combustion engine that performs feedback control so that boost pressure becomes the target boost pressure, detecting that boost pressure exceeds a predetermined value during a transient state of boost pressure, and The feedback control is started after a predetermined time has elapsed after it was detected that the predetermined value was exceeded.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of a control device 6 for an internal combustion engine equipped with a turbocharger to which the control method of the present invention is applied. The symbol l in the figure indicates, for example, a six-cylinder internal combustion engine, and the engine! An intake pipe 2 is connected to the first stream side, and an exhaust pipe 3 is connected to the downstream side, and a turbocharger 4 is interposed between the intake pipe 2 and the exhaust pipe 3.

The intake pipe 2 is provided with an air cleaner 5, an intercooler 6, and a throttle valve 7 in this order from the upstream side.

An atmospheric pressure (P^) sensor 8 is installed between the air cleaner 5 at one end of the intake pipe 2 and the turbocharger 4 to detect the intake pressure in the intake pipe section between them, that is, the atmospheric pressure. The detection signal is supplied to an electronic control unit (hereinafter referred to as rECUJ) 9.

A throttle valve opening (OT11) sensor 10 is connected to the throttle valve 7 to convert the valve opening of the throttle valve 7 into an electrical signal and send it to the ECU 9.

On the other hand, the intake pipe absolute pressure (P
BATC) sensor 11 is provided, and this P BA
The absolute pressure signal converted into an electrical signal by the TC sensor 11 is sent to the ECUO.

In this embodiment, the PBATC sensor 11 executes feedback control in the substantially fully open region of the throttle valve 7 during boost pressure control by the turbocharger 4, as will be described later. The magnitude of the supercharging pressure can be detected as the intake pressure value of the intake path portion obtained by the Pa^TC sensor 11 provided downstream of the throttle valve 7. Therefore, ECU9
Under the throttle valve fully open condition, information regarding the boost pressure is also supplied from the PIIATC sensor 11.

Further, downstream of the PBATC sensor 11, the intake air temperature (1゛^
) A sensor 12 is attached, which detects the intake air temperature T^ and outputs a corresponding electric signal to supply it to the ECU 9.

A fuel injection valve 13 is provided in the intake pipe 2 between the engine l and the throttle valve 7. This fuel injection valve 13 is provided for each cylinder slightly upstream of the intake valve of the intake pipe 2 (2
each injection valve 13 is connected to a fuel pump (not shown) and electrically connected to the ECU 9.
A signal from the ECU 9 controls the opening time of fuel injection, that is, the amount of fuel supplied.

The engine rotation speed (Ne) sensor 14 is installed around the camshaft or crankshaft (not shown) of the engine l and is connected to the ECU 9, and outputs a '1' DC signal, that is, every 180° rotation of the crankshaft of the engine l. outputs l pulse at a predetermined crank angle position, and converts this pulse into IE C[
Supply to J9.

Further, a three-way catalyst 15 is arranged downstream of the turbocharger 4 in the exhaust pipe 3 .

The turbocharger 4 is of a variable displacement type, and its operation control system is an actuator having a drive rod 16 linked to a movable vane 64 (FIG. 3) of the turbocharger 4, which will be described later. 7, a duty-controlled electromagnetic control valve 18 for introducing supercharging pressure (hereinafter simply referred to as "control valve"), and a regulator 19.

FIG. 2 shows an overall configuration diagram of the turbocharger 4. That is, the turbocharger 4 includes a compressor casing 41 forming a scroll of the compressor portion, and the compressor casing 4! a back plate 42 that closes the back surface of the turbocharger 4; a bearing casing 44 that pivotally supports the main shaft 43 of the turbocharger 4 and has a structure that lubricates the bearing and circulates cooling water; and a turbine casing that forms the scroll of the turbine section. 45.

Inside the compressor casing 41, there are formed a scroll passage 46 and an axial passage 47, to which the intake pipe 2 is connected, respectively.
7 constitutes an intake inlet.

In the intake man rj l'll, a compressor boiler 48 is attached to one end of the main shaft 43.

The main shaft 43 is supported in the bearing hole 49.50 of the bearing casing 44 by a radial bearing metal 51 and a thrust bearing metal 52.

Further, the bearing casing 44 is formed with a lubricating oil introduction hole 53, a lubricating oil passage 54, a lubricating oil discharge ['' 55], and a water jacket 56.

Inside the turbine casing 45, a scroll passage 5 is provided.
7 and its population 11 tangentially 1j old −1
57 a, an output 1-1 passage 58 extending in the axial direction,
An exit 1' opening 58a is formed, and an input 1' opening 58a is formed.
t+57 ts and output 1-1 1158 a are connected to the exhaust pipe 3, respectively.

The outer circumference of the fixed vane member 60 fixed to the back plate 59 so as to be disposed in the center of the scroll passage 57 includes:
As shown in FIG. 3, a plurality of fixed vanes 62, for example, four fixed vanes 62, are formed so as to concentrically surround a turbine wheel 61 provided at the end of the main shaft 43. These fixed vanes 62 each have a partial arc shape, and are provided with the same width and at equal intervals along the circumferential direction. A movable vane 64 is disposed between each fixed vane 62 and is fixed to the free end of a rotating bin 63 rotatably attached to the back plate 59 .

These movable vanes 64 have an arc shape with the same curvature as the fixed vanes 62, and are located on approximately the same circumference. It is possible to rotate between 11).

The gaps between the fixed vanes 62 are opened and closed by the movable vanes 64 being rotated in synchronization, and the circulation area of each gap corresponds to the inclination angle of the rotating claws, that is, the movable vanes 64. will be adjusted accordingly.

The synchronous rotational drive of each movable vane 64 is achieved by a rotational bin 63 supporting each, a link mechanism 65 (Fig. 2) connected to the rotational bin 6:□3, and a linkage mechanism 65 connected to the rotational bin 63. This is done by means of its actuator 17 via the previously described drive rod 16 (FIG. 1). The drive rod 16 and the link mechanism 65 are such that when the drive rod 16 is operated in the extension direction (to the left in FIG. 1), the opening degree of each movable vane 64 increases and each gap circulation surface +s1 increases. When operated in the contraction direction (rightward in Fig. 1), the opening degree decreases and the flow area of each gap becomes small. The capacity of the turbocharger 4 is adjusted ff1i.

That is, in the variable capacity turbocharger 4 having the -1-2 configuration, the exhaust gas discharged from the engine 1 body is
Turbine side input [1 passage 57J1 to scroll passage 5
Exhaust gas flows into the turbine wheel 61 side at a flow rate according to the flow area of the gap between the movable vane 64 and the fixed vane 621flJ according to the rotary claw of the movable vane 64, and drives the turbine foil 61 to rotate. Exit 1-1 aisle 58
is discharged from. The flow velocity of the exhaust gas that drives the turbine wheel 61 depends on the air gap flow area described in 1.
iJ If the flow area of the gap between the moving vane 64 and the fixed vane 62 is small and the flow velocity is high, the turbine wheel 61, i.e. -
1:.

When the rotational speed of the shaft 43 increases and the flow rate of the gap between each movable vane 64 and the fixed vane 61 is large and the flow velocity is low, the rotational speed of the turbine wheel 61, that is, the main shaft 43 becomes slow. Since the compressor wheel 48 rotates in accordance with the rotation of the turbine wheel 61, the air led from the air cleaner 5 to the axial passage 47 is compressed by the compressor wheel 48 according to its rotational speed, and passes through the scroll passage 46 to the intercooler. Supplied towards 6,
The intake air will be pressurized.

Thus, when the movable vane 64 is located at the outermost radial position of the turbine casing 57 and the air gap circulation area between it and the fixed vane 62 is minimized, that is, when the opening degree is minimized, the supercharging pressure is maximized, and the movable vane 64 to turbine casing 5
When the air gap flow surface 141 between the movable vane 64 and the fixed vane 62 is at its maximum, that is, the opening is set to 7 barley, the supercharging pressure is at a minimum, and the opening of the movable vane 64 is A high boost pressure state can be easily obtained by adjustment, and]
In the range between the minimum and maximum of the two records, the supercharging pressure can be changed in a wide range according to the opening degree.

The actuator 17 that rotationally drives the movable vane 64 of the turbocharger 4 for controlling the boost pressure is a
It has a pressure chamber +7b and a second pressure chamber +7c, and the drive rod 16 described above passes through the housing on the second pressure chamber +7c side and is connected to the diaphragm 17a. The spring 17d inserted into the second pressure chamber 17b is connected to the diaphragm 1.
7a is the direction in which the drive rod 16 is contracted, that is, the uj
The movable vane 64 is biased in a direction to decrease the opening degree.

An intake passage between the air cleaner 5 and the turbocharger 4 is connected to the first pressure chamber 17a via a throttle 22, and an intake passage between the turbocharger 4 and the intercooler 6 is connected to the regulator 19, the throttle 23, and the control valve 18. connected via.

The control valve 18 is a normally closed on-off two-position operating type solenoid valve, and has a solenoid 18a and a solenoid I8t>.
The valve body 18b is opened by the excitation of the valve body 18b. When the valve body 181) is opened by the force of the solenoid 18a, the supercharging pressure in the intake passage between the turbocharger 4 and the intercooler 6 is introduced into the first pressure chamber 17b of the actuator 17.

In this case, the diaphragm 17a is deflected so as to extend the drive rod 16, and the movable vane 64 of the turbocharger 4 is moved inward through the drive rod 16 and the link mechanism 65, that is, in the direction in which the opening degree is increased. Rotationally driven. When the valve body 18b is closed, the introduction of supercharging pressure is cut off, and contrary to the above, the movable vane 64 is driven in a direction in which its opening degree becomes smaller.

Therefore, the valve body 18b in one cycle of on-off of the solenoid 18a, that is, opening and opening of the valve body 18b.
', that is, the valve closing duty ratio Dva (hereinafter simply referred to as "duty ratio"), this is in the 100% state (when the movable vane 64 is at 0; the minimum opening position described above, From the maximum boost pressure state), the magnitude of the boost pressure is controlled according to the duty ratio Dvc.

The solenoid l 8 n of the control valve 18 is 1): f
The duty ratio Dva is controlled by a signal from ECLJ9.

Furthermore, t=c U 9 is the vehicle speed (V) that detects the vehicle speed.
A sensor 24 is connected and its detection signal is supplied.

The ECUO includes an input circuit 9a that has functions such as shaping input signal waveforms from various sensors, correcting voltage levels to predetermined levels, and converting analog signal values into digital signal values.
Central processing circuit (hereinafter referred to as rcPUJ) 9b, CP
It is composed of a storage means 9c that stores various calculation programs and calculation results executed by the IJ 9b, and an output circuit 9 (1, etc.) that supplies drive signals to the fuel injection valve 13 and control valve 18.

The CPU 9b determines the operating state of the engine 1 based on human power from the various sensors described above, and optimizes various characteristics such as fuel efficiency and acceleration characteristics according to the determined operating state. The fuel injection time and the like of the fuel injection valve 13 are calculated, and a drive signal based on the calculation result is supplied to the fuel injection valve 13 via the output circuit 9d.

In the above fuel injection time calculation, the basic fuel injection time, that is, the basic valve opening time 'rl of the injection valve 13, is 'P5
Ti (not shown) stored in the storage means 9C described above is determined according to the intake pipe absolute pressure I'B^ based on the detection outputs of the Atc sensor 11 and the Ne sensor I4 and the engine rotation speed Ne.
Calculated from the map.

In addition, the CPU 9b sets an open loop control region, a feedback control region, etc. for boost pressure control according to the engine operating state based on input signals from various sensors and according to a control program to be described later. In addition to determining whether the
A drive signal for operating the control valve 18 is supplied via the output circuit 9d in accordance with the calculated value, and the control valve 18 and further the actuator 17 linked to the turbocharger 4 are driven.

FIG. 4 shows a flowchart of a program for controlling the duty ratio 1)vc of the control valve 18, that is, the boost pressure.

First, in step 401, 1) stored in the IECU 9
From the van map, the duty ratio l)vc base rllll[Dvcr+ is read out according to the throttle valve opening OTll and the engine speed Ne.
An example of the +n map is shown, where the throttle valve opening OTl+ is set in 16 steps from 0 to +vt to OTIIV16 within a predetermined range, and the engine speed Ne is set to Nv+- within a predetermined range.
There are 20 stages as wNv20,
Standard value 1) V is calculated by interpolation at points other than the grid points of the map.
M is required for . By setting n to the reference value 1)V using such a map, the duty ratio 1)vc of the control valve 18 can be controlled in more detail according to the operating state of the engine l.

Next, it is determined whether the gear position of the transmission (hereinafter simply referred to as "gear position") is at the first speed (lsL) position (
Step 402). This determination is performed, for example, according to the subroutine shown in FIG.

That is, the vehicle speed V is a predetermined speed VL that is normally obtained at the first speed position.
First, it is determined whether the value is smaller than step 601),
When V≧VL holds true, it is determined that the vehicle is not in the first speed position (step 602). On the other hand, in step 601, V
(When VL holds true, it is determined whether the vehicle speed V is smaller than a predetermined value Vp according to the engine speed Ne (step 603), and when V≧Vp holds, the step 602 is executed, while V( When V p is established, it is determined that the vehicle is in the first speed position (step 604).
.

FIG. 7 shows a table for determining the predetermined value Vp. That is, when the gear position is in the first gear position, the ratio between the engine speed Ne and the vehicle speed V is in a constant relationship, so the base 711j value Npt to NF9 of the engine speed No is adjusted to match this relationship. and the reference value Vp+ of the vehicle speed V
VF[ is set in advance as a table, and it is determined that the vehicle is in the first speed position when the vehicle speed V is smaller than a reference value Vp corresponding to the actual engine speed Ne. With this configuration, it is possible to determine whether or not the gear position is in the first gear position without using a gear position sensor or the like, not only when the transmission is a manual transmission, but also when it is an automatic transmission. can be done easily.

Returning to FIG. 4, the answer to step 402 determines 1” (Y
es), that is, when the gear position is at the first speed position, the duty ratio 1) base Qtl value of vc determined in step 401 is subtracted from the predetermined value Dp from 1) vcr+, and 1
After resetting 7M to the nuclear base/llj value 1)V (step 403), if the result is negative (No), that is, if the gear position is at a position other than the second speed, the process directly proceeds to step 404. In this way, the basis of the duty ratio Dva? Ill value 1) VGM
is set to a smaller value by a predetermined value I)p when the gear position is at the first speed position than when the gear position is at a position other than the first speed.

In step 404, the KV stored in IF, Cu2
From the T^ map, engine speed Na and intake temperature 1゛^
According to this, intake temperature hl + positive coefficient 1<Vd^ is read out.

FIG. 8 shows an example of this KVT^ map, and the engine speed Ne is Nv+ to N as in the above 1) vcr+ map.
20 stages as V2O, intake QTA is 'l"^vt~"
Eight levels are provided as l'^ve, and the intake temperature correction coefficient KVT^ can be set more appropriately using such a map.

Next, the change m (hereinafter simply referred to as "change amount") Δ[)B^ in the intake pipe absolute pressure PBATC is calculated from the current value Pn^T
It is calculated based on the difference between the O port and the value P BATCI+-1 three times before (step 405). This change mΔPe^ is
As will be described later, this is applied to set various constants for calculating the duty ratio Dva, and thereby the increasing gradient of the supercharging pressure is controlled to a desired value.

Next, in step 406, it is determined whether the boost pressure is in a state that requires open loop control. This determination is made according to the subroutine shown in FIG.

First, in step 901, the throttle valve opening degree On+ is
It is determined whether the opening is larger than a predetermined opening □FR indicating that the opening is fully open (m), and if the answer is negative (No), that is, OT.
If 1≦Opo is established and the throttle valve 7 is not in a substantially fully open state, it is determined that open loop control should be performed and the process proceeds to step 916 to be described later. That is, the feedback control is executed only when the throttle valve 7 is substantially fully open.

The answer to step 901 is F! When r is constant (Yes), that is, the throttle valve is almost fully open, it is determined whether or not feedback (1?/13) control has been performed in the 1111th loop (step 902), and this answer is 11 constant (Yes). At this time, it is determined that feedback control should be continued.03)
Exit this program.

The answer to step 12 of Oij is negative (No), that is, 0.
When the open loop control is being performed in the 11th time, it is determined whether the gear position is in the first gear position (Step 004), and if it is in a position other than the first gear, [ΔPIIASI stored in the ECU 9] From the table, find the first subtraction value ΔP8ASD for positions other than the first speed according to the change amount formula PB^ (step 005)
, proceed to step 907, which will be described later. Figure 10 shows this ΔPB
An example of the ASD table is shown, and two reference values ΔPa^1 and ΔPB^2 (>ΔP11^
1) is set, and the larger the ΔPa^ value, that is, the greater the rising gradient of the supercharging pressure, the larger the first subtraction value Δ[)I]^ is set. )＋
ΔP[1ASD3 to ΔPBASDI are set for 1^1 or more and ΔI)B^2 and ΔPq^2 or more, respectively.

When the answer to step 904 is affirmative (Yes), that is, the gear position is at the first speed position, the first subtraction value ΔP
8^so is set to a predetermined value ΔI'1lASDF for the first speed position (step 906), and the process proceeds to step 907.

The predetermined value ΔP eAsop is set to a value larger than the Δp8^so value for positions other than the first speed, which is determined in step 905.

Next, in step 907, the intake pipe absolute pressure P BA
TC is the target value P BATI! O and the step 0
The first subtraction value ΔPBAS obtained in 05 or 906
It is determined whether or not the difference is greater than the difference with D (P BATRG - ΔPBAS port) (hereinafter referred to as minimum opening control release pressure J).

The above-mentioned target value P8^τta of the intake pipe absolute pressure is set according to the engine rotation speed Ne, intake air temperature '1'^, and gear position in the control program shown in Fig. 4, as will be described later. .

If the answer to step 907 is negative (No), that is, the intake pipe absolute pressure P IIATC is equal to the minimum opening control release pressure (P BA
When TR[+-Δ['1lASD) or less, both the proportional control term DVP% integral control term Dvi, which will be described later and is applied to feedback control, are set to the value 0.0.Step 9
08,900), then set the duty ratio Dva to 100%.
In other words, the movable vane 64 is set to the minimum opening degree (step 910). That is, P BATC≦(PII
ATl! When c-ΔPIIAS11) holds,
The minimum opening degree control of the movable vane 64 is executed (between to and t^ in Fig. 18), and through this control, the increasing gradient of the supercharging pressure on the low supercharging pressure side is controlled to the maximum, and the pressure is brought close to the desired pressure value. The responsiveness of the boost pressure +l111g9 can be improved by increasing the boost pressure of the boost pressure more quickly.

Next, LPIII for feedback 11me control delay)
To reset the LY timer, step 911) proceeds to step 418 in FIG. 4, outputs a drive signal based on the duty ratio Dva to the control valve 18, and
lll Exit the program.

Returning to the subroutine of FIG. 9, step 1; step 907 of FIG.
If the answer is affirmative (Yes), that is, the intake pipe absolute pressure P BAT
C is the minimum opening control release pressure (P eAtI!a-ΔP[1
ASI)), it is determined whether the gear position is in the first gear position or not (step 1312), and if it is in a position other than the first gear, the
From the BAFB table, find the second subtraction value ΔP8^FB for positions other than the first speed according to the amount of change APR^ (
Step 013), the process proceeds to step 015, which will be described later.

Figure 1I shows an example of the PRAFB table, and just like in Figure 1O, the base full for the variation formula PII^ is shown.
l value ΔPa^+, APIIA2 is set, ΔeeAt
Droplets, △P8^1 or more but less than ΔPB^2 and ΔPI]^2
For the above, ΔPI]^PB3~8PuApR
t (Δ[)BAFI+3〈ΔPBAP112＜8P
IIAFRI) is set.

Is the answer to step 912 1? When the gear position is at the 1st speed position, the second subtraction value Δ[)0^FB is set as the predetermined value Δl'RAF for the 1st speed position.
If the BF is set (step 914), the process advances to step 915.

The predetermined value ΔPBApnp is Δ1)llAFll for positions other than the first speed, which is obtained in step 913 of n;j.
The field is set to be larger than the F value.

Next, in step 915, the intake pipe absolute pressure P[1A
TC is the target value 1) BATRG and the step 91
PIIA to the subtracted value of WS2 obtained in 3 or 914
Difference from F[l (P BATI!O−ΔpHAFl+)
(hereinafter referred to as "feedback control start pressure") (step 915). If the answer is negative (NO), that is, when the intake pipe absolute pressure Pn^Te is equal to or higher than the feedback control start pressure (Pn^TRG-ΔPBAFB), it is determined that oven loop control should be performed, and the process proceeds to step 916 and subsequent steps. That is, (1) nArg
c −ΔP nASo)<I)8^TC≦(1'BASL0−Δ1)l]^F11) When J holds true, open-loop control is executed (Fig. 18 Nomu~Lnlf
ll).

In this step 916, ll'l nt step 91
1, the FBDLY timer is reset, and then it is determined whether the gear position is at the first speed position (step 917). If this answer is negative (No), LE
From the 1]■ table stored in the CU9, find the subtraction term DT for positions other than the 1st speed, which will be described later, and which is applied to the open loop control, according to the change amount ΔPn^ described in 1).
Step 918), the process proceeds to step 921, which will be described later.

FIG. 12 shows an example of this Dr table, and in exactly the same way as FIG. 10, the base t1111+! for the amount of change ΔPa^! I
ΔPs^1. ΔPB^2 is set, less than ΔPn^1,
ΔPII^1 or more and ΔPs^2 or more and to Pn^2 or more -1
; respectively, DTI to DT3 (DTl(Dr2
(Dr3) is set.

+fij Step 91 (T constant (Yes), that is, when the gear position is at the 1st speed position, 1) FT child table stored in the ECUO, the amount of change ΔI) B^
The subtraction term Dpr for the first speed position is determined in accordance with (step 919). FIG. 13 shows an example of this DFT table, in which two base 1111 values Δ are calculated for the amount of change ΔPII^.
PnAp+ and Δ[)llAP2 (>ΔPBAFl)
is set, and DFTI~D FT3(D pr+ (D FT2<
DFT3) is set.

Next, the subtraction term DT is set to the 1) FT value obtained above (step 020), and in step 921 it is determined that oven loop 111 control should be executed, and this program is ended.

Thus, when the throttle valve 7 is almost fully opened, the above-mentioned minimum opening control that forcibly sets the duty ratio 1)vc to 100% is executed, and when the control is released, open loop control is executed. That will happen.

Specifically, the open loop control is executed according to the calculation of the duty ratio Dvc, the limit check, and the output processing in steps 425 to 2/10.418 described later in FIG. 4, and in this process, I) IIATc value is ,
The state progresses as shown in FIG.

That is, although the degree of increase in PaArcffi is reduced by −Jλ at time t^, it still shows an upward trend.

In step 1] 15, in this process, the magnitude of the supercharging pressure, that is, in this embodiment, the intake pipe absolute pressure PIIA
T(: (monitoring direct, 1); J step O1'
, ) is [7 constant (Yes), that is, the absolute pressure in the intake pipe P8
ATC uses feedback control starting pressure (P n^tl!c
-ΔPBAF11), after the LFBDLY timer is reset in step 011 or 016 (in the example of FIG. 18, the reset time in step 91G is taken as the starting point), the predetermined time t,
Determine whether p old rule Y has elapsed (step 922
). If this answer is negative (No), step 91
The process proceeds to step 7 to perform open-loop control, while if the answer is affirmative (Yes), it is determined that feedback control should be performed, and the process proceeds to step 923. in this way,
The intake pipe absolute pressure PsArc is the feedback control start pressure (1)n^τl! G-Δ1)llAFB), instead of immediately performing feedback control, open-loop control is executed from this time until a predetermined time tFnl)LY has elapsed (ILII to c in Fig. 18).
clfll), feedback control is executed for the first time after lapse of time (after tc in the figure).

As a result of the above, the intake pipe absolute pressure PIIATC is set to a predetermined value (1α
(PBATI!G-ΔPBAF[+) and after a predetermined time 1, F11IILY has elapsed, it is determined that the steady state (1) and feedback control is started, so when transitioning from oven loop; I; control to feedback control. Also, stable boost pressure control performance can be obtained.

That is, the characteristic shown by the broken line 11 in FIG. 18 shows the change in the boost pressure when the feedback control start delay control described in "U" is not executed, and the transition to the feedback control 91 is made as in the comparative example. If the determination of whether or not the
If a predetermined 111" (hereinafter referred to as "stable" state) which is lower than the standard boost pressure by a predetermined number of nails is determined to be a constant state and feedback control is started, as shown in the figure, over-short and under-show I. will occur, and hunting will occur. It takes time for the actual boost pressure to converge to the target boost pressure, increasing the period of instability.

On the other hand, due to the delay angle LF old Y timer mentioned above,
nf;ffi! According to Surisei, who applied J-go, I'BA
Even if TC>(P BAT * low ΔPBAFB),
Before the predetermined time tFBDLY elapses, oven loop control is continued. Therefore, (P IIATI!G-Δ
More specifically, the PBAFB) value means the feedback control start condition determination pressure.

Thus, as a result of the open-loop control that should be applied as boost pressure control in a transient state being maintained under certain conditions, as shown by the solid line I in FIG.
Compared to Comparative Example H, overshow etc. can be significantly reduced, and stable and appropriate supercharging pressure control can be achieved.

By waiting for the predetermined time t FBDLY to elapse, the hunting phenomenon as shown in characteristic 11 of the comparative example subsides during that period, and therefore, the hunting phenomenon at the start of feedback control (
tc) in Figure 18, the actual PB^TC value (supercharging pressure)
Since the feedback control region is entered in a state where the deviation between the target value P nArRa and the target value P nArRa is small, 11 points ill P IIA
TI! Convergence to G is achieved early, and moreover, after a predetermined period of time L FBDLY has elapsed, the control is switched to feedback control. This can be avoided, and the transition to feedback control can be smoothly and reliably performed as quickly as possible.

In particular, the control described in ``--'' performs the minimum opening control described in +) ii to improve responsiveness during a sudden start by fully opening the throttle valve or sudden acceleration from cruising, as in this embodiment. This is more effective when accelerating the rise of charge pressure, and allows for expansion of boost pressure control that reduces hunting and the like.

When entering the feedback control region, the actual intake pipe absolute pressure PBATC and the target value P aAr11! pass through step 923.003 and step 407 in FIG. 4, which will be described later. POATC according to the deviation from a
Feedback 111 control is executed in which the control claw is determined and the supercharging pressure triltj9 is adjusted so that the value becomes the target value PBAg.

That is, in step 923, 11;1 distribution integral control term D
The initial value of vi is calculated according to the following equation (1).

Dvi=Kv ding^XDvar+X (KvREpi,
j −1) −(1) Here, KvREpij is
This is a customary correction coefficient calculated during feedback control according to the program shown in FIG. 4 as described later.

Next, the process proceeds to step 903, where it is determined that feedback control should be performed and the program is ended.

Returning to the program in FIG. 4, in step 407 following step 406, it is determined whether open loop control is determined to be performed by the subroutine in FIG. 9 executed in step 40G.

If this answer is negative (No), that is, it is determined that feedback control should be performed, the target absolute pressure in the intake pipe is determined from the P BATRG map stored in the ECU 9 according to the engine speed Ne and the intake temperature T^. Value P B
The AT information is read (step 408).

FIG. 14 shows an example of this Pa＾dRG map, which is exactly the same as the Kvτ＾ map described above, based on the engine speed Ne. The base 7111 values TAVt to TAV6 of 11riNvt to NV2O and the intake air temperature '1'^ are set, and the target value PnArga can be set more appropriately using such a map.

Next, in step 409, it is determined whether or not the gear position is in the first gear position, and if it is in the first gear position, the predetermined value Pn obtained in step 408 is
Ari! After subtracting t;p (step old O) and resetting the 11 target value P nArRa, when the gear is in a position other than the first speed, the process directly proceeds to step old l. in this way,
[1 Target price PsArl! t; is a predetermined value 1)llATl! when the gear position is in the first gear position than when it is in a position other than the first gear position. Only OF is set to a smaller value.

In this step 4+1, 0: deviation ΔPs (= PnArl
! a - PnATC), and then calculate the deviation to the absolute value of PB 1Δ1) where port 1 is a predetermined value Gai (e.g. 20 m
Determine whether it is greater than or equal to mmm1l (step 41
2). This predetermined value G old is a dead zone defining pressure during feedback control.

If the answer to step 412 is +' (Yes), that is, 1
When ΔPBl≧G++i holds, IE C(J
From the Kvr table and Kvi table stored in 9, the constants KVP and Kvi of the proportional control term DVP and the integral control term vi are determined according to the engine speed Ne.
(old step 3). FIGS. 15 and 16 are diagrams showing examples of the Kvr table and Kvi table, respectively. That is, in the Kvr table, there are two base qlI values N for the engine speed Ne.
K! /P and NKVP2 (>NKVPI) are set, and the constant KVP is set as Kvr+ to Kvr3(Kvr+ (Kvrz(Kvr
3), and in the Kvi table, two reference values Nxv are set for the engine speed Ne.
i+ and Ncvi2()N Kvi) are set, and the constant Kvi is less than Ncvi+ and greater than or equal to NKvi+ NKvi2
Kvi 1 for Ncvi less than 2 and Ncvi 2 or more, respectively.
~Kvi3 (Kvi3<Kvi I(Kviz) is set.

Next, the proportional control term 1) vr is expressed as the constant K
In step 4), set the integral control term Dvi to the product KVP・muPn of VP and the deviation ΔPa.
The sum of n and the integral control term Dvi calculated up to the previous time (=
I) vi + Kvi - ΔPB) (step 415).

Next, the proportional and integral control terms L)vr and Dvi set above are applied to calculate the duty ratio Dvc during feedback control according to the following equation (2) (step old 6).

Dvc=Dvar+XKvy^+Dvt+1)vi
...(2) Next, the calculated duty ratio 1) vc
Perform a limit check to determine the duty ratio 1) v
c is maintained within a predetermined range (step 417), and a drive signal based on the duty ratio Dva is sent to the control valve 18.
(old step 8) and exit this program.

The answer to step /112 is negative (NO), that is, 1ΔI
) n 1 (Gni holds, therefore 11 target price Pn^
When rRG and the actual intake pipe absolute pressure 1) nATC almost match, the proportional control term Dvr is set to 0.0, and the integral control term 1) vj is set to its previous value 1) vi. step old 0.420).

Next, it is determined whether the gear position is at the first speed position (step 421), and if it is at a position other than the first speed,
Calculate the coefficient Kvg according to the following equation (3) (step 4
22).

This coefficient KVR represents deviations in boost pressure control due to variations due to mass production or changes over time.

Next, "Learning correction coefficient Kvl!" using the coefficient Kvt!
ppij is calculated according to the following equation (4). (Step 4
23).

...(4) Here, Kvl of the second term on the right side! The Epij value is a learning correction coefficient obtained up to the previous time, and depending on the engine speed Nc and the intake air temperature '1゛^, the KVI! Read from the EF map. Also, A is a constant, and CvREp is 1 to
This is a variable of A that is experimentally set to an appropriate value.

Kvt! according to the value of the variable CVREF! Since the ratio of Kvg value to +, pij changes, this CV RE p
An optimal value of 1(vtEpij) can be obtained by setting ll'I to an appropriate value within the range of 1-A according to the use of the target boost pressure control device, engine, etc.

Next, the calculated learning correction coefficient KvI! epi
, i in the KVREF map provided in the backup RAM in EC:U9 (step 424), I
This program is completed by executing step 6 and subsequent steps described in "rη." FIG. 17 shows an example of this KVREF map.

That is, KvI! The εF map is divided into a plurality of regions according to the engine speed Ne and the intake temperature T^, similar to the KVT^ map (Fig. 8) and the 1)llATRG map (Fig. 14), and the Ne value and the 1゛^ value are Kv for each applicable area
gI: pjj value is calculated and stored.

The answer to step 407 is 11 (Yes), that is, the 9th
When it is determined by the subroutine in the figure that oven loop control should be performed, KVREF in +iiij.
The learning correction coefficient KVRεFij is read from the map according to the engine speed No. and the intake air temperature 'r^ (step 425), and then the proportional control term 1) VP and the integral control term Dvi are both set to the value O6O (step 426).
427).

Next, the duty ratio Dv during oven loop control
c is calculated according to the following equation (5) (step 428).

Dva=Kvy^XKvRepijX (Dvcn-D
T) - (5) where DT is the subtraction term set in step 918 or 920 of the subroutine of FIG.

Next, perform a limit check of the calculated duty ratio 1) VO, for example, set the Dvc value to 0% or more.
In order to maintain the value at 0% or less, step 429) and step 418 are executed, and the program ends.

In this embodiment, the boost pressure is detected by the intake pipe absolute pressure 1) BATc sensor downstream of the thrower 1 hell valve, but the intake pipe part upstream of the throttle valve and downstream of the turbocharger is A dedicated supercharging pressure detection sensor may be provided to detect the supercharging pressure.

In addition, a timer tFI for delaying the start of feedback control
For IDLY, prepare several types in advance according to the rate of change in boost pressure, and set a small delay time when the boost pressure is changing slowly, and set a large delay time when the boost pressure changes rapidly. It is also possible to adopt a configuration that applies the above, and in this case, when transitioning to feedback control and hunting control, it is possible to set a delay time that is just enough to avoid the hunting phenomenon. can be set.

Furthermore, in this embodiment, as a supercharger capable of controlling boost pressure,
Although the description has been given using an example of a turbocharger in which the capacity is changed by operating movable vanes, the present invention is not limited to this, and can also be applied to wastegate type and supercharging pressure relief type turbochargers. Furthermore, the present invention may also be applied to control of boost pressure in a so-called supercharger driven by the output power of an engine.

(Effects of the Invention) According to the present invention, the control amount is determined according to the deviation between the actual boost pressure and the [142 boost pressure, and n
In a method for controlling the boost pressure of an internal combustion engine that performs feedback control so that the boost pressure in jj becomes the target boost pressure in 011, it is detected that the boost pressure exceeds a predetermined value during a transient state of the boost pressure. , and the feedback control is started after a predetermined period of time has elapsed after it is detected that the predetermined value has been exceeded, so that a transient state accompanied by a sudden change in the magnitude such as a sudden increase in supercharging pressure is avoided. In addition to preventing an abnormal increase in boost pressure and the occurrence of hunting phenomenon,
It is possible to ensure a smooth and prompt transition to feedback control, and it is possible to make boost pressure control more stable and appropriate, especially during acceleration.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Fig. 1 is an overall diagram of a control system for an internal combustion engine with a turbocharger to which the control method of the present invention is applied, and Fig. 21-1 is a longitudinal sectional view of the turbocharger. , Figure 3 shows the 21ff Ill-I
Fig. 4 is a flowchart of a program for calculating the duty ratio 1)ve of the control brake r, and Fig. 5 shows the reference value 1.ve of the duty ratio Dvc. ) Van map, (Figure 5 is the flowchart 1 of the subroutine for determining the gear position of the transmission, Figure 7 is a diagram showing the VF table applied to the subroutine of Figure 6, Figure 8 9 is a diagram showing a map of the intake temperature correction coefficient 1 (vr^), FIG. 1st for positions other than speed
Subtraction value Δ1) Diagram showing the table of BAsll, No. 11
The figure shows the second subtraction value Δ1) BAFl for positions other than 1st speed.
Figure 12 shows a table of + for positions other than 1st speed.
Figure 13 shows a table of subtraction term DT for t.
Figure 14 shows a table of subtraction term DPT for speed position, and Figure 14 shows a map of target value P8^1'RG of boost pressure1)
1. Fig. 15 is a table showing the constant Kvp of the proportional control term I) VP, and Fig. 16 is a table showing the constant Kvp of the integral control term Dvi.
A diagram showing a table of i, FIG. 17 is a learning correction coefficient KVR
Figure 5 shows the EF map. Figure 18 shows the absolute pressure in the intake pipe of 1".
FIG. 8 is a diagram showing the IyI relationship between 8^re and supercharging pressure control. 1... Internal combustion engine, 4... Turbocharger, 9
...Electronic control unit, 5...Absolute pressure in the intake pipe ([)n^re) sensor, 17...Actuator, 18...Electromagnetic 11-metre control valve, Pn^Tc...Absolute pressure in the intake pipe (Supercharging pressure), 1) Port ^TPli..."1
Target value (target boost pressure), Dvr;...Duty ratio (
control (21 quantities), PaArta-ΔP++Apa-feedback control start pressure (feedback control start condition discrimination pressure; predetermined value). Applicant ITJ Giken Kogyo Co., Ltd.

Claims (1)

[Claims] 1. An internal combustion engine that determines a control amount according to the deviation between an actual boost pressure and a target boost pressure, and performs feedback control based on the control amount so that the boost pressure becomes the target boost pressure. In the supercharging pressure control method, it is detected that the supercharging pressure exceeds a predetermined value during a transient state of the supercharging pressure, and after a predetermined period of time has elapsed after the detection that the supercharging pressure has exceeded the predetermined value, A method for controlling boost pressure of an internal combustion engine, characterized in that feedback control is started.