JPH01178722A - Controlling method for variable displacement turbocharger - Google Patents

Abstract

PURPOSE:To perform stable supercharging control by decreasing both of desired supercharging pressure and fundamental supercharging controlled variable when engine speed varies from an accelerated state to a decelerated one. CONSTITUTION:Those of intake pressure PA, supercharging pressure PZ, engine speed NE, throttle opening theta, car speed V and a shift position signal of an automatic transmission are all inputted into a control means C, and an actuator 60 for a movable vane is driven on the basis of these input signals. When engine speed varies from an accelerated state to a decelerated one, both of desired supercharging pressure and fundamental supercharging pressure controlled variable are decreased. With this constitution, an overshoot value is abated after detecting a fact that it is in a shift change time by behavior of the engine speed, so that stable supercharging pressure control is thus performable.

Description

Detailed Description of the Invention A9 Objective of the Invention (1) Industrial Application Field The present invention controls the capacity of a variable displacement turbocharger based on a basic boost pressure control amount corresponding to the operating state of an engine, and The present invention relates to a control method for a variable displacement turbocharger in which a basic boost pressure control amount is corrected in accordance with a deviation between an actual boost pressure and a target boost pressure when the operating state of an engine is in a feedback control region.

(2) Conventional technology Conventionally, there is a variable displacement turbocharger that improves engine output by changing the capacity according to the operating state of the engine, for example, as disclosed in Japanese Patent Application Laid-open No. 192942/1983. .

(3) Problems to be solved by the invention By the way, the torque applied to the transmission member in the power transmission mechanism differs depending on the shift position in the transmission.
It becomes excessive especially at the first speed position. Therefore, in the above-mentioned conventional gear, the supercharging pressure is lowered in the first gear position to lower the torque applied to the transmission member, thereby reducing the size of the transmission.

However, when the engine speed drops during a transmission shift change, the boost pressure will not correspond to the engine speed even though the engine speed has decreased due to a time lag between the activation of the means to adjust the boost pressure. Otherwise, overshoot may occur, making stable control difficult.

The present invention has been made in view of the above circumstances, and provides a variable displacement turbo that detects shift changes based on the behavior of engine speed, reduces overshoe 1-1, and enables stable boost pressure control. The purpose of this invention is to provide a method for controlling a charger.

B1 Structure of the Invention (1) Means for Solving the Problems According to the method of the present invention, target supercharging is performed when the engine speed changes from an accelerating state to a decelerating state under preset operating conditions of the engine. The pressure and basic supercharging pressure J&U amount were reduced.

(2) Effect According to the method described in 1, it is detected that it is time for a shift change by changing the engine speed from an accelerating state to a decelerating state, and in the open loop control region, the basic boost pressure control amount is In the feedback system 91U region, the target supercharging pressure is respectively reduced, so that the supercharging pressure corresponds to the engine speed, reducing the amount of overshoot, and enabling stable supercharging pressure control.

(3) Embodiment Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. An intake manifold 1 is connected to the intake port of each cylinder on the side of the engine body of a multi-cylinder internal combustion engine, and this intake manifold 1 is further connected to an intake pipe. 2, connected to an air cleaner 6 via a throttle body 3, an intercooler 4, and a variable displacement turbocharger 5. In addition, an exhaust manifold 7 is connected to the exhaust ports 1 to 1 of each cylinder, and the exhaust manifold 7 is connected to a catalytic converter with a built-in three-way catalyst via an exhaust pipe 8 with a variable capacity turbocharger 5 interposed in the middle. Connected to 9. Further, fuel injection valves 10 for injecting fuel toward the intake ports of each cylinder are installed in a portion of the intake manifold 1 close to each intake port.

The variable capacity turbocharger 5 is provided with a water jacket 11, and the inlet of this water jacket 11 and the inlet of the ink cooler 4 are connected in parallel to the discharge port of a water pump 13 whose suction port is connected to the radiator 12. , water pump 13
And the outlet of the ink cooler 5=4 is connected to the radiator 12. Furthermore, the radiator 12 is provided separately from the cooling water radiator in the engine body E.

Next, the configuration of the variable capacity turbocharger 5 will be explained with reference to FIGS. 2, 3, and 4. It includes a plate 15, a bearing casing 17 that supports a main shaft 16, and a turbine casing 18.

A scroll passage 19 is defined between the compressor casing 14 and the back plate 15, and the compressor casing 1
An inlet passage 20 extending in the axial direction is formed in the central portion of 4. Moreover, a compressor wheel 21 is attached to one end of the main shaft 16 in the central portion of the scroll passage 19 and located at the inner end of the inlet passage 20.

The compressor casing 14 and the back plate 157 are fastened together by a plurality of bolts 22, and the bearing casing 17 is connected to the center of the back plate 15.

A pair of bearing holes 23.24 are coaxially drilled in the bearing casing 17 at a distance from each other, and the main shaft 16 and the bearing holes 23, 24 are inserted into these bearing holes 23.24.
Radial bearing metals 25 and 26 are interposed between them, respectively, so that the main shaft 16 is rotatably supported by the bearing casing 17. Further, a collar 27, a thrust bearing metal 2B, and a bushing 29 are interposed between the step portion 16a of the main shaft 16 facing the compressor wheel 21 side and the compressor wheel 21 in order from the step portion 16a side. By screwing and tightening the nut 30 that abuts the outer end of the main shaft 16 to one end of the main shaft 16, the main shaft 16 is supported in the thrust direction and the compressor wheel 21 is attached to the main shaft 16.

A lubricating oil introduction hole 32 connected to a lubricating oil pump (not shown) is provided in the upper part of the bearing casing 17, and a lubricating oil introducing hole 32 is provided in the bearing casing 17 to the radial bearing metal 25, 26 and the thrust bearing metal 28. A lubricating oil passage 33 is bored to guide the supplied lubricating oil.

Further, a lubricating oil outlet 34 is provided in the lower part of the bearing casing 17 for discharging the lubricating oil flowing out from each lubricating part downward. collected in the sump.

The bushing 29 is disposed through a through hole 35 bored in the center of the back plate 15, and is arranged through a through hole 35 formed in the center of the back plate 15.
A seal ring 36 is interposed between the outer surface of the bushing 29 and the inner surface of the through hole 35 in order to prevent lubricating oil flowing out from the bushing 8 from flowing toward the compressor wheel 21 side.

Further, a guide plate 37 is sandwiched between the back plate 15 and the thrust bearing metal 28 and allows the bushing 29 to pass therethrough. Therefore, the lubricating oil flowing out from the thrust bearing metal 28 is scattered radially outward from the bushing 29 and the guide plate 3
It is accepted at 7. Moreover, the lower part of the guide plate 37 is curved to smoothly guide the received lubricating oil to the lubricating oil outlet 34.

The bearing casing 17 is provided with a water jacket 11 around the main shaft 16, and a water supply port 38 for guiding water from the water pump 13 (see FIG. 1) to the water jacket 11, as well as a water jacket 11. A water outlet 39 is provided for guiding water from the radiator 12 to the radiator 12 (see FIG. 1). In addition, the water jacket 11 is formed in a circular ring shape surrounding the main shaft 16 in the part near the turbine casing 18, and in the part corresponding to the upper part of the lubricating oil discharge port 34, it is formed in a substantially U-shape that opens downward above the main shaft 1G. The water supply port 38 is formed to have a cross-sectional shape, and the water supply port 38 is connected to the water jacket 11.
A water outlet 39 is bored in the bearing casing 17 to communicate with the lower part of the water jacket 11, and a water outlet 39 is bored in the bearing casing 17 to communicate with the upper part of the water jacket 11.

A scroll passage 41, an inlet passage 42 communicating with the scroll passage 41 and extending in the tangential direction, and an outlet passage 43 communicating with the scroll passage 4I and extending in the axial direction are provided in the turbine casing 18.

Bearing casing 17 and turbine casing 18 are coupled to each other with back plate 44 sandwiched therebetween. That is, a plurality of stud bolts 45 are screwed into the turbine casing 18, and the bearing casing 17
The bearing casing 17 and the turbine casing 18 are connected to each other by tightening the ring member 46 that engages with the stud bolt 45 with the Nand 47 that is screwed into the stud bolt 45. and the turbine casing 18.

A fixed vane member 48 is fixed to the back plate 44, and the fixed vane member 48 divides the inside of the scroll passage 41 into an outer circumferential passage 41a and an inflow passage 41b. The fixed vane member 48 has a cylindrical portion 4 coaxially fitted in the outlet passage 43.
8a, a disk portion 48b extending radially outward from the outer surface of the intermediate portion of the cylindrical portion 48a, and a plurality of, for example, four, fixed vanes 49 extending from the outer peripheral end of the disk portion 48b toward the back plate 44 side. A turbine boiler 50 provided at the other end of the main shaft 16 is housed within the fixed vane member 48. The cylindrical portion 48a is fitted into the outlet passage 43 through a seal ring 51 fitted on the outer surface thereof, and the fixed vane 49 is coupled to the back plate 44 by bolts 52.

The fixed vanes 49 are provided on the outer periphery of the turbine member 48 at equally spaced positions in the circumferential direction, and each fixed vane 49 is formed in an arc shape. Also, between each fixed half 49, a back plate 4 is arranged parallel to the axis of the main shaft 16.
Movable vanes 54 having one end fixed to a rotation shaft 53 rotatably connected to the fixed halves 4 are arranged, and the flow area of the gap between the fixed halves 49 is adjusted by these movable vanes 54.

Each movable vane 54 is formed in an arc shape with the same curvature as the fixed vane 49, and is rotatable between a fully closed position shown by a solid line in FIG. 3 and a fully open position shown by a chain line. Moreover, each rotation shaft 53 is connected to the actuator 6 via a link mechanism 55 arranged between the back plate 44 and the bearing casing 17.
0, and each movable vane 54 is driven to open and close in synchronization with the operation of the actuator 60.

A shield plate 56 extending to the back of the turbine foil 50 is sandwiched between the back plate 44 and the bearing casing 17, and the heat of the exhaust gas flowing through the inflow path 41b is directly transferred to the inside of the bearing casing 17 by this shield plate 56. This will be prevented as much as possible. In addition, exhaust gas flows into the bearing casing 1.
In order to prevent the main shaft 16 from leaking into the turbine casing 18, the main shaft 16 is located at a portion corresponding to the through hole 57 provided in the bearing casing 17 to allow the main shaft 16 to protrude into the turbine casing 18.
A plurality of annular grooves 58 are provided which function as labyrinth grooves.

In such a variable capacity turbocharger 5, exhaust gas discharged from the engine body E is transferred from the artificial passage 42 to the outer circumferential passage 41a.
Exhaust gas flows into the inlet passage 4Ib at a flow rate corresponding to the flow area of the gap between the movable vane 54 and the fixed vane 49, which corresponds to the amount of rotation of the movable vane 54, and rotates the turbine wheel 50 to form the outlet. It is discharged from the passage 43. At this time, when the flow area of the gap between each movable vane 54 and the fixed half 49 becomes smaller, the rotational speed of the turbine wheel 50, that is, the output shaft 16 becomes faster, and the flow area of the gap between each movable vane 54 and the fixed half 49 becomes larger. Then, the rotational speed of the turbine wheel 50, that is, the main shaft 16 becomes faster. The compressor wheel 21 rotates in accordance with the rotation of the turbine boiler 50, and the air led from the air cleaner 6 to the inlet passage 20 is supplied to the ink cooler 4 through the scroll passage 19 while being compressed by the compressor wheel 21. It turns out. Therefore, when the movable vane 54 is located at the outermost position in the radial direction of the turbine casing 18 to minimize the air gap flow area between it and the fixed vane 49, the boost pressure is maximized, and the movable vane 54 is positioned at the outermost position in the radial direction of the turbine casing 18. The supercharging pressure becomes the minimum when the air gap circulation area between the vane 49 and the fixed vane 49 is maximized by locating it radially inward.

The upper limit of the temperature of the bearing casing 17 caused by a 1 rise in the temperature during air compression in the variable capacity turbocharger 5 is prevented as much as possible by supplying cooling water to the water jacket 11, and an increase in intake air temperature is prevented from increasing by 1 to the ink cooler 4. This can be prevented by supplying cooling water.

Referring again to FIG. 1, the actuator 60 for driving the movable vane 54 of the variable displacement turbocharger 5 is
A housing 61 and a first pressure chamber 6 inside the housing 61.
a diaphragm 64 that partitions the diaphragm 64 into a second pressure chamber 63 and a second pressure chamber 63; The link mechanism 5 is connected at one end to the central portion and passes through the housing 61 airtightly and movably on the second pressure chamber 62 side.
5 and a driving roller 6 connected to the other end thereof. Furthermore, when the drive rod 66 and the link mechanism 55 are bent in the direction in which the diaphragm 64 contracts the second pressure chamber 63 and the drive roller 6 is extended, each movable vane 54 is moved inward in the radial direction of the turbine casing 18. It is connected so as to rotate and increase the air gap circulation area between the fixed vanes 49 and each fixed vane 49 .

An intake path between the variable displacement turbocharger 5 and the inktor 54 is connected to the first pressure chamber 62 via a regulator 67, a throttle 68, and an electromagnetic control valve 69 to supply supercharging pressure P2, and the air cleaner 6 and Intake passages between the variable capacity turbochargers 5 are connected via a throttle 75. This electromagnetic control valve 69 is duty-controlled, and as the duty ratio of the solenoid 70 increases, the pressure in the first pressure chamber 62 increases. The movable vanes 54 of the variable turbocharger 5 are driven to rotate inward. In addition, a check valve 7 is provided in the second pressure chamber 63 so that an intake passage downstream of the throttle body 3 supplies the intake pressure PR.
1 and an electromagnetic on-off valve 72. This electromagnetic on-off valve 72 opens in response to the excitation of the solenoid 73, and the second electromagnetic on-off valve 72 opens in response to the opening of the solenoid 73.
When the intake pressure PB is supplied to the pressure chamber 63, the actuator 60 moves the movable vane 54 of the variable displacement turbocharger 5.
drive inward.

Solenoid 70 of electromagnetic control valve 69 and electromagnetic on-off valve 72
The excitation and demagnetization of the solenoid 73 is controlled by a control means C, which includes an engine main body E.
Water temperature T w of the water jacket (not shown) provided inside
, an intake air temperature sensor SA that detects the intake air temperature TA on the downstream side of the ink cooler 4, and an intake pressure sensor SPA that detects the intake pressure P between the air cleaner 6 and the variable displacement turbocharger 5. , a supercharging pressure sensor SP2 that detects the supercharging pressure P2 in the intake passage between the variable displacement turbocharger 5 and the inktor 54, an intake pressure sensor SPB that detects the intake pressure PB downstream of the throttle body 3, and the engine. A rotation speed detector SN that detects the rotation speed NE, a throttle opening detector SA, 1 that detects the opening degree θTH of the throttle valve 74 in the throttle body 3, a vehicle speed detector Sv that detects the vehicle speed V, and an automatic A shift position detector S for detecting a shift position in the transmission is connected. The control means C receives these input signals, namely, the water temperature T,1, the intake air temperature TA, and the intake pressure P.
A, supercharging pressure P2, intake pressure PR1, engine speed N.

, throttle opening θ1H1, vehicle speed (2), and the shift position signal of the automatic transmission, the excitation and demagnetization of the solenoids 70 and 73 are controlled.

Next, the control procedure in the control means C will be explained. First, the duty control of the solenoid 70 in the electromagnetic control valve 69 will be explained with reference to the main routine shown in FIG. However, in this main routine, duty D is used to control the excitation and demagnetization of the solenoid 70. As the value of UT increases, the duty ratio of the solenoid 70 decreases; DOUT=O corresponds to a duty ratio of 100%, and DOUT=100 corresponds to a duty ratio of O%.

In the first step S1, it is determined whether the engine is in the starting mode, that is, whether the engine is cranking. If the engine is in the starting mode, the duty is set to D in the second step S2. ol is set so that the electromagnetic control valve 69 is fully opened and the air gap circulation area between the movable vane 54 and the fixed vane 49 is maximized. This is because the engine is in an unstable state during cranking, and introducing supercharging pressure into the combustion chamber in such an unstable state will aggravate the instability. This is to avoid supercharging pressure being introduced into the combustion chamber by maximizing the air gap flow area between the two. Further, during cranking, the driver does not request supercharging of air supply, and there is no need to reduce the air gap circulation area between the movable vane 54 and the fixed vane 49. In the next third step S3, the timer tFB[lLY for delaying the start of feedback control is reset, and then the duty D is reset from the fourth step S4.

Ul is output.

The timer tFRDLY is calculated according to the procedure shown in FIG.
One of LYZ·t p++ntvz is selected. Here, the rate of change ΔP2 is the current supercharging pressure Pan,
Difference from the 6th previous supercharging pressure P Zl'l-6 (ΔPz = P
2. IPZ, 1-6). That is, the main routine shown in FIG. 5 is updated by the TDC signal, but
Since the rate of change in supercharging pressure P2 is too small with only one TDC signal, in order to accurately read the supercharging pressure behavior, that is, the rate of change ΔP2, we calculated the difference from the previous supercharging pressure P2n-6 six times. It is something. In addition, the setting high change rate 8P ZPT
L and set high rate of change ΔP2FT11 are engine speed N,
It is predetermined according to ΔP2≦ΔP
At the time of 2PTL, tFllDl and Yl are set,
When ΔP zpTL<ΔP2≦ΔP2PTI+, t
FEDLY2 is set, and when ΔP2PTH<ΔP2, tFBDL73 is set. Moreover, tFB
DLYI < t FEDLY2 < tFEDLV3, and when the boost pressure change rate ΔP2 is small = 21- In other words, when the boost pressure P2 is changing slowly, the delay time is small (set, and the boost pressure change rate ΔP2 is large) In other words, when the boost pressure P2 is rapidly changing, the delay time is set to be large.

As a result, an appropriate time t FEDLY is set at the time of transition from open-loop control to feedback control, and it becomes possible to sufficiently avoid the hunting phenomenon at the time of the transition.

When it is determined in the first step S1 that the engine is not in the start mode, it is determined in the fifth step S5 whether the water temperature TI, , is less than the set low water temperature T, A+, and if the set low water temperature T is less than 1. If so, proceed to the second step S2.

Here, the operating state of the engine that can be considered as a case where T11<TIIL is established is, for example, when the engine is starting up or when the outside temperature is extremely low. If the condition continues and the outside temperature is extremely low, the intake air density increases, which increases the charging efficiency and causes abnormal combustion. At times like this,
Introducing supercharging pressure into the combustion chamber promotes engine instability and abnormal combustion. Further, at extremely low temperatures, the electromagnetic control valve 69 itself may malfunction, and there is a possibility that the electromagnetic control valve 69 may not behave as instructed by the control means C.

Therefore, when Tヮ〈Tヮ, the second step S
Proceed to 2. u, −〇.

If it is determined in the fifth step S5 that T8≧T91 or less, the process proceeds to a sixth step S6. In this sixth step S6, the water temperature T9 is set to the set high water temperature T00. It is determined whether or not the high water temperature exceeds the set high water temperature TW11, and if the set high water temperature TW11 is exceeded, the process proceeds to the second step S2. Possible cases where T>TIIH holds are, for example, when the engine continues to operate under high load, when the outside temperature is extremely high, or when an abnormality has occurred in the cooling water system of the engine body E. Cases etc. In all of these conditions, the intake air density decreases, that is, the charging efficiency declines, which causes abnormal combustion such as unburned fuel. Introducing supercharging pressure into the combustion chamber when the engine is in an unstable state will aggravate the unstable state, so the duty D is set in the second step S2. Ul
-0. Also, at extremely high temperatures, solenoid 7
The zero inductance characteristic is likely to change, and there is a possibility that the behavior will differ from the set behavior in the normal state, and in order to avoid such a situation, the second step S2 is proceeded to. When it is determined in the sixth step S6 that T≧T and 1u, the process advances to a seventh step S7. The water temperature T is set at a low water temperature T1 or higher, and the set high water temperature is T8.
□ If the value is within the following range, proceed to the seventh step S7; otherwise proceed to the second step S2.

In the seventh step S7, the supercharging pressure P2 is set to a high supercharging pressure determination guard value P2NG, which is set in advance as shown in FIG.
It is determined whether or not P2>P2HG is satisfied, the process proceeds to the second step S2, and when P2≦P2HG, the process proceeds to the eighth step S8. Here, the high boost pressure judgment guard value PZIIG changes depending on the engine speed N, and is set so that the maximum output can be obtained below the knock limit value corresponding to the engine speed NE. be. In the limit low rotation speed range, the torque applied to the transmission member in the low gear is positive, and in the limit high rotation speed range, the durability of the engine body E is positive, and P2HG is set lower than in the medium rotation speed range. When a supercharging pressure P2 exceeding this high supercharging pressure determination guard value pzo6 is detected, the second and third steps S2. In a fourth step S4 after passing through S3, the duty ratio is set to 100% to lower the supercharging pressure P2 and fuel injection is cut.

In the eighth step S8, a basic duty D as a basic boost pressure control amount is searched. The basic duty D is set in advance according to the engine speed NE and the throttle opening θT++, and the basic duty D is determined from the setting table. is searched.

In this way, by searching the basic duty ratio I as the basic boost pressure control amount using the map determined by the engine speed NE and the throttle opening θ1H, each operating state of the engine can be accurately determined. This is because deceleration or transient operating conditions cannot be accurately determined based on the engine speed N alone or the throttle opening θTl+ alone. Although the throttle opening θTII is used as a representative parameter indicating the engine load condition, the same effect can be obtained by replacing it with the intake pressure PE or the fuel injection amount.

In the next ninth step S9, it is determined whether the shift position of the automatic transmission is at the first speed position, and if it is at the first speed position, the process proceeds to the tenth step SIO, When in the shift position, the eleventh step 31
．． Go to 1.

At the tenth step SIO, the basic duty D is subtracted according to the subroutine shown in FIG. In other words, a determination zone in which weight loss is required according to the operating condition determined by the engine speed N and intake pressure PR is preset as shown by diagonal lines in FIG. Basic duty D depending on whether it is outside the zone
It is determined whether or not to subtract M. By the way, the 9th
In the figure, changes in engine torque are observed based on engine speed N and -intake pressure Pn, and the boundary line of the discrimination zone indicates the allowable torque amount of the gear shaft at the first speed position. That is, the first
To prevent the force applied to the gear shaft from becoming overloaded in the high speed position,
As shown in Figure 9, the engine speed N,
The judgment is made accurately based on the intake pressure P8. When it is outside the discrimination zone, the basic duty D remains unchanged and the process proceeds to the 12th step SL2, but when it is within the discrimination zone, it is determined whether the flag F is O (JJ), that is, whether it is in the feed bank control state. After that, when in the open control state, the beams =D, -D,
When in the feedback control state, a subtraction of P2REF-P2REF-ΔP2REFF is performed. Here, D is a preset subtraction value. Furthermore, P2REF is a target supercharging pressure used in the feedback control state, and P2RFP is a preset subtraction value, which will be explained in detail in the feedback control section below.

At the eleventh step Sll, the basic duty DM is subtracted according to the subroutine shown in FIG. In other words, the suntle opening degree θ. H is the set throttle opening θTl
(Exceeds the OS, the engine speed N exceeds the set speed NEO3, the intake pressure PR exceeds the set intake pressure PEO3, the rate of change ΔN of the previous engine speed N is positive, the current engine speed When the rate of change ΔNE of N, is negative, a subtraction called DM-Dos is performed when in the open control state, and P2RE is subtracted when in the feedback control state.
A subtraction of F''''P2REF-ΔP2REFOS is performed, and in other cases, the basic duty DM is left as is and the process proceeds to the twelfth step S12. Here it is.

3. ΔP 2 REF. 5 is a preset subtraction value.

In the twelfth step S12, it is determined whether the throttle opening θTl+ exceeds a preset throttle opening θTIIFB. This set throttle opening θT
HFE is set to determine whether to shift from open loop control to feedback control. By employing the throttle opening degree θ1M as a determination parameter, it is possible to accurately determine whether the driver is requesting acceleration, that is, supercharging. When θT11≦θ, 1□6, that is, when continuing open loop control, the 13th step S1
At step 3, the delay timer trr++++ty shown in FIG. 6 is reset, and the process further advances to the 14th step S14.

In the fourteenth step S14, the duty correction coefficient is +
Search onij. This correction factor is correct. Dij is searched using a map determined by the engine speed NE and intake air temperature TA, and is learned when the optimum boost pressure P2 falls within a predetermined deviation as described later, and is updated at any time based on this learning. Ru. Now enter the correction coefficient. . The initial value of 8 is 1.

In the next 15th step S15, a duty atmospheric pressure correction coefficient Kpnrc (0.8 to 1.0) is determined corresponding to the intake pressure PA, and in the next 16th step = 30-S16, a duty intake temperature correction coefficient is determined. A coefficient KTATC (0°8 to 1.3) is determined corresponding to the intake air temperature TA.

In the seventeenth step S17, a set subtraction duty DT corresponding to the rate of change ΔP2 of the supercharging pressure P2 is determined according to the subroutine shown in FIG. In other words, throttle opening θT
When H is larger than the set throttle opening θT It F B, the setting determined by the rate of change ΔP2 of the supercharging pressure P2 and the engine speed NE is applied as shown in FIGS. 12(a), (b), and (C). Subtraction duty D7 is selected and θ
When TH≦θTHFB, it is determined as DT-〇.

FIG. 12(a) shows the first switching rotation speed NFB+ (for example, 3000 rpm) where the engine rotation speed NY is preset.
m) Indicates the setting subtraction duty D when it is below,
Fig. 12(b) shows that the engine speed NE is the first switching speed NF.
BL and the second switching rotation speed NFB2 (for example, 4
500rpm) or less setting subtraction duty D
, and FIG. 12(C) shows the set subtraction duty D when the engine speed N is less than the second switching speed NFE□.
It shows T. Here, the set subtraction duty D1 is such that the set value DST lower than the target boost pressure P2REF is processed from when the actual boost pressure P2 becomes large, as shown in FIG. 21, which will be described later. This is to prevent overshoot when P2 rises. Moreover, as shown in FIG. 12 and above, the engine speed N
! and the charge is changed according to the boost pressure change rate ΔP2,
If this is the engine speed NE when reaching the set value P 2ST
Since the amount of overshoot differs depending on the charging pressure change rate ΔP2, the purpose of this is to optimize the duty control in each operating range by changing the holding position. Here, the larger ΔP2 and the larger NE are, the larger Dl is set.

Furthermore, in the 18th step 318, the set addition duty D_TRII is determined according to the subroutine shown in FIG. That is, when the rate of change ΔP2 of supercharging pressure P2 is in a negative state during open loop control, -ΔP2 as shown in FIGS. 14(a), (b), and (C).
The set addition duty D7RB set according to the engine rotational speed NE is selected, and the set subtraction duty DT is set to O.

Further, when ΔP2 is positive in the feedback control state, the set addition duties DT and 1B are set to O.

This set addition duty DT, 1B also has the engine speed N, similar to the set subtraction duty DA described above. The position is changed as shown in FIG. 14 according to the boost pressure change rate -ΔP2 of and -, and the larger NE is, the larger -ΔP2 is. R11 is set to be large, which results in stable supercharging pressure P with less hunting in each operating range.
It becomes possible to perform duty control such that 2 is obtained. That is, from the start of operation, the predetermined area P23. Up until. UT-1
00, the movable vane 54 is set to the fixed vane 49 so that the Shiita gap circulation area is minimized to increase the supercharging pressure P2, and after the supercharging pressure P2 exceeds the set pressure P2ST, the settings for overshoot prevention are made. By adding the set addition duty DTRB to prevent hunting that occurs as a reaction to the subtraction duty D, stable supercharging pressure control can be performed in each operating range. Therefore, the fourth
The output duty D1 output from step S4 is set by comprehensively taking into account the detailed contents and the operating state of the engine, taking into account external factors.

In this way, the correction coefficient Kaoni= + KPATC+
After KtAte, the set subtraction duty DT and the set addition duty DT□ are determined, the process proceeds to the 19th step S1.
Proceed to step 9.

-34=Duty D in the 19th step S19. LIT is corrected by the following equation.

DOIIT = KTATCX KPATCX KMo
nt, Check.

In other words, the duty D depends on the engine speed N.

A limit value is set in advance, and it is checked whether it deviates from the limit value, and if it does not deviate from the limit value, the duty D is set in a fourth step S4. L.I.
T is output.

When it is determined in the 12th step S12 that θTH>θTl (FE), the process proceeds to the 22nd step S22. In the 22nd step S22, it is determined whether the previous flag F is 1, that is, if the previous time was an open loop tlilJ.
If F=1, supercharging pressure P2 is set to open loop Q in the 23rd step S23.
Duty control start determination supercharging pressure P23. It is determined whether the This duty control start determination supercharging pressure P 2ST is P 2ST - P 2REF - ΔP
2ST, and ΔP251 is the first
As shown in Figure 5 (a), (b), and (C), the engine speed N
It is set according to E. Here, the 8P 2ST, like the above-mentioned DT and DTIIB, is changed according to the engine speed NE and boost pressure change rate △P2 in order to shift the optimum duty control 9Ju, and the engine speed It is set to increase as NE increases and as boost pressure change rate ΔP2 increases.

When P2>PZST at the 23rd step 323, it is determined at the 24th step 324 whether the supercharging pressure P2 exceeds the feed-hack control start determination supercharging pressure P2FB. This feed puncture control start determination supercharging pressure P2□ is obtained by P2□-P211EF-ΔP2F8, and ΔP2FB is as shown in FIGS. 16(a), (b),
As shown in (C), it is set according to the engine rotation speed Nr. This feed puncture control start determination supercharging pressure P 2
FB is also similar to the above ΔPzsT, DA, D, R8,
It is switched depending on the engine speed NE and boost pressure change rate ΔP2 in order to perform optimal duty control, and as the engine speed NE increases, the boost pressure change rate ΔP2 increases.
is thick (so it is set to be large. This second
If P2>P2Fll in the fourth step S24, the process advances to the 25th step S25.

In the twenty-fifth step 325, the delay timer tFIIOL'
It is determined whether / has elapsed, and if it has elapsed, the process advances to the 26th step S26. If F=0 in the 22nd step S22, the process bypasses the 23rd to 25th steps 323 to S25 and proceeds to the 26th step S26, and if P2≦P2ST in the 23rd step S23, the process proceeds to the 27th step S27. 24th step S24
When P2≦P2FB, the 13th step S1
3, in the 25th step S25, the delay timer tFEDL
If the time period has not elapsed, the process advances to the fourteenth step S14.

In the 27th step S27, the duty is D. ul is 100
Then, in the 28th step S28, the timer tFII
DLY is reset and the process proceeds to the fourth step S4.

In the twenty-sixth step S26, it is determined whether the absolute value of the boost pressure change rate ΔP2 exceeds the feedback control determination boost differential pressure GdP2. This feedback control determination supercharging differential pressure G4,2 is set to, for example, 30 mm Hg, and when the absolute value of ΔP2 exceeds the feed hack control determining supercharging differential pressure GdP2, the process returns to the 14th step S14, and the absolute value of ΔP2 is determined. is less than the feedback control determination supercharging differential pressure GdP2, the process advances to the 29th step S29. Here] If feedback control is started when ΔP2 1 > Gap2, hunting will occur, so the process returns to the 14th step S14 and open loop control is performed.As mentioned above, in open loop control, Dl, DTRI+ Since the correction is performed to prevent hunting and overshoot, the main focus of the 26th step S26 is to perform a fail-safe function.

Feedback control is started from the 29th step S29, and first, at the 29th step S29, the target supercharging pressure P2REF, which is preset based on the engine speed N and the intake air temperature TA, is searched. Here, the foot bank control first starts with θT in the twelfth step S12.
1. 〉It is assumed that θTIIFB is satisfied, and under this condition, the target supercharging pressure P2R1F determined by the engine speed NE and intake air temperature TA is searched as a parameter that can accurately judge the operating state of the engine. It is. θTH>θTHFB That is, in a high load state of the engine, the engine speed NE and the throttle opening θTl+ exhibit almost the same behavior, and NE is an effective parameter indicating the operating state of the engine. In addition, the intake air temperature TA is the intake air temperature on the downstream side of the ink cooler 4 as shown in FIG. 1, and is a parameter that accurately indicates the state of the intake air introduced into the combustion chamber. Therefore, the target boost pressure P 2R is determined by the map determined by the engine speed NE and the intake air temperature TA.
By determining EF, it is possible to set a value that immediately corresponds to the operating state of the engine.

In the next 30th step S30, it is determined whether the shift position of the automatic transmission is the first gear position.

When the vehicle is in the first speed position, in step S31, according to the subroutine shown in FIG.
The calculation REF - P 2 REF - ΔP 2 REFF is performed, and the process advances to the 33rd step S33. This ΔP 2
REFF is a subtraction value that is set when the shift position is at the first speed position. Also, the 30th step S3
0 and the shift position is determined to be at a position other than the first speed position, in the 32nd step S32, P 2REF =
The calculation P2REF−Δp2REFO5 is performed,
The process advances to the 33rd step S33. Moreover, ΔP 2 REF
O5 is a subtraction value that is set when the shift position is in a state other than the first speed position.

In the 33rd step S33, the atmospheric pressure correction coefficient KPAP2 for boost pressure and the atmospheric pressure correction coefficient KP, To for duty, which are preset according to the intake pressure P, are determined.
Furthermore, the following calculation is performed in the 34th step S34.

P 2REF-P 2REF X K PAP2 X
K REFTI! In the above formula, KREFTB is a correction coefficient corresponding to the knock state of the engine.

In the 35th step S35, it is determined whether the absolute value of the deviation between the target boost pressure P2REF and the current boost pressure P2 is greater than or equal to the set value G,2. The set value G,2 is the dead zone defining pressure during feedback control, for example, 20 m
It is set to about mHg. When the absolute value of the deviation between the target supercharging pressure P2REF and the actual supercharging pressure P2 is greater than or equal to the set value CP2, the process proceeds to the 36th step S36, and when it is less than the set value CP2, the process proceeds to the 43rd step S43.

In the 36th step S36, the duty proportional control term is calculated using the following equation.

Dr −KP In FIG. 17, when the engine speed NE is equal to or lower than the first switching speed NFB+, KPI is obtained, and a feedback coefficient K11 related to the integral control term described later is obtained.
is obtained, and the engine speed NE is the first switching speed N F B
+ and is less than or equal to the second switching rotation speed NFB2, KP2. 1□ is obtained, and when the engine speed NE exceeds the second switching speed NFE2, KP3. 3 is obtained.

In the 37th step S37, the above-mentioned 14th step S14
Similarly, +4oniJ is searched for in the correction coefficient according to the engine speed NE and the intake air temperature TA, and in the 38th step 3
In step 3B, it is determined whether the previous flag F is 1, that is, whether this is the first foot control λ/link control state, and if F=1, the process proceeds to the 39th step S39.
The previous integral control term DI(□-3) is calculated according to the following equation.

D I +11-11-ni Ding ATCX KPATCX
DMX (KMont; 1) After completing this calculation, the process proceeds to the 40th step S40, but if F=O in the 38th step S38, the process proceeds to the 39th step S39.
The process bypasses the process and proceeds to the 40th step S40.

In the 40th step S40, the current integral control term DI,
is calculated according to the following equation.

D+n=I)zn-++++''-(P ZREF
Pz) Thereafter, in the 41st step 341, the duty 1)ot+a is calculated. That is, DOUT = KTATCX KPATCX DM +
The calculation Dr + D + n is performed, and after setting the flag F=O in the 42nd step S42, the flag F is set to O in the 21st step S42.
Proceed to step 21.

Further, when the absolute value of the deviation between the target boost pressure P2R correction and the actual boost pressure P2 is less than the set value CP2 in the 35th step S35, the process proceeds to the 43rd step S43, and -0, D,
,,=D I +11-11. Then the 44th
In steps S44 to 47th step S47, the water temperature T. ie TIIIMOI+. whether it exceeds T□ODH, the retard amount T2□,
KR
It is determined whether EFTE is less than or equal to 1.0, and if all of these conditions are met, the process proceeds to the 48th step S48.
If even one of these conditions is not met, proceed to the fourth step.
Proceed to step S41.

In the 48th step 348, the duty correction coefficient is
. . , J is calculated according to the following equation.

KR= (KTATCX D, 4+ D +,,) ÷ (
(KTATCXDM) Next, in the 49th step S49, the correction coefficient KM.

In order to search and learn 9.1, (65536C
Mon ) 9.4 is stored.

According to such duty control of the solenoid 70 in the electromagnetic control valve 69, the shift position of the automatic transmission is set to the first shift position.
If the engine is in the oven loop control state, the basic duty DH is set to D when the operating state of the engine is in the determination zone shown in FIG.
F is subtracted by 46, and in the feedback control state, the 31st step S31
When the target supercharging pressure P2 is in the discrimination zone,
REF is subtracted by ΔP 2REF. Therefore, overload on the automatic transmission due to sudden start or overload when the shift position is at the first speed position can be prevented by reducing the supercharging pressure as the basic duty D decreases. Furthermore, even if the open-loop control is shifted to the feedback control while maintaining the first speed position, since the target supercharging pressure P2REF is subtracted, it is possible to prevent hunting from occurring during the shift.

Further, assume that a shift change as shown in the lower part of FIG. 20 is performed. In this case, when changing gears,
While the engine speed N increases, there is a time lag in the operation of the actuator 60 by the control means C. Therefore, the boost pressure P2 does not correspond to the engine speed NE, and overshoot occurs, causing the boost pressure P2 to reach the limit value, especially during a shift change immediately after acceleration from a medium to high speed range, as shown by the broken line in Figure 18. There is a risk that it will exceed. However,
At the 11th step Sll and the 32nd step S32, the duty D and the target supercharging pressure P2□ are subtracted according to the subroutine shown in FIG. That is, at the time of a shift change, the throttle opening degree θTH is set to a predetermined value θa.

. 3, the engine speed NE exceeds the predetermined value NI:O5, and the intake pressure PR exceeds the predetermined value PEOS, that is, in response to the rate of change ΔP2 of the boost pressure P2 in the middle and high speed ranges,
In open loop control, the basic duty is D4. , and in feedback control the target boost pressure P Z
REF is subtracted by ΔP 2 REFO9.

As a result, as shown by the solid line in FIG. 18, overshoot at the time of shift change can be significantly reduced, hunting phenomenon can be avoided, and stable supercharging pressure control can be achieved.

Furthermore, when shifting from open-loop control to feedback control, the drop in supercharging pressure P2 can be covered, as shown in FIG. 19, and the shift can be quickly shifted to feedback control. In other words, duty is D at the start of operation. During open loop control when LIT is O, that is, the duty ratio is 100% and the throttle opening θT)I is less than the set throttle opening θT II F 8, DT- It is set to 0. and θT11>DT
117 B, the transition from open loop control to feedback control starts, but when boost pressure P2 reaches P
23. When θT11>DT)IFB, overshoot is prevented by setting DeeD4DT.

However, when Dl is subtracted as described above, the supercharging pressure P2 may drop as shown by the broken line in FIG. 19 due to the reaction. However, if ΔP2≦0, it is set as D7-0, and Δ
If P2〉O, only DT□ is added, so
It is possible to quickly shift to feedback control by covering the drop in supercharging pressure P2, and it is possible to expand supercharging pressure control without the hunting phenomenon.

The duty control of the solenoid 70 in the electromagnetic control valve 69 described above is performed while the electromagnetic on-off valve 72 is closed, and when this electromagnetic on-off valve 72 is opened,
Intake pressure P is applied to the second pressure chamber 63 in the actuator 60.
, the actuator 60 is configured such that the movable vane 54 of the variable displacement turbocharger 5 is connected to the fixed vane 49 of the variable displacement turbocharger 5.
It operates in the direction of increasing the air gap circulation area between.

Next, the procedure in the control means C for controlling the solenoid 73 of the electromagnetic on-off valve 72 will be explained with reference to FIG. Here, in addition to controlling the operation of the electromagnetic control valve 69 for introducing supercharging pressure P2 into the first pressure chamber 62 of the actuator 60 based on the main routine of FIG. By introducing the intake pressure P8 via the closing valve 72, more precise control becomes possible. This is because the supercharging pressure P2 is detected between the variable displacement turbocharger 5 and the inktor 54, so the minute operation of the throttle valve 74 cannot be detected, whereas the intake pressure PR is detected from the downstream side of the throttle valve 74. This is because the minute actuation of the throttle valve 74 can be detected since it is derived. In other words, the operation of the entire intake system including the turbocharger 5 is made more accurate by both the supercharging pressure sensor SP2 that reliably detects the movement of the turbocharger 5 and the intake pressure sensor spB that reliably detects the movement of the throttle valve 74. It becomes possible to reflect.

In the first step L1, it is determined whether a predetermined time, for example, two minutes, has elapsed after the engine has been started. If the predetermined time has not elapsed, the process proceeds to a second step L2, where the solenoid 73 is energized and the actuator 60 controls the movable vane. 54 operates in a direction to increase the flow area between the fixed vane 49 and the fixed vane 49.

This is to deal with cold starting, prevents supercharging during cold times, and allows the catalyst temperature to rise gradually. If a predetermined time has elapsed in this first step L1, the process proceeds to a third step L3, where it is determined whether the vehicle speed V exceeds a judgment vehicle speed VOP3 set with hysteresis, for example, 90/87+n/h. is,
When V>VOP3, proceed to the fourth step L4,
V≦V OP ], the process proceeds to the fifth step L5.

In the fourth step L4, the throttle opening degree θ is determined. H is the set throttle opening change rate ΔθT□. It is determined whether it is less than P2. This set throttle opening change rate θTHO
P2 is set with hysteresis, and Δθ, 1
1〈ΔθTl1OP2, the second step L2
Otherwise, the process proceeds to the fifth step L5.

In the fifth step L5, the vehicle speed ■ is the set vehicle speed ■. It is determined whether it is less than P1. The set vehicle speed VOP+ has hysteresis, for example, 65/63k.
m/h. If V<VoPI, the process proceeds to the seventh step L7, and if ■≧VOP+, the process proceeds to the sixth step L6, where the solenoid 73 is demagnetized. Also the 7th
At step L7, the vehicle speed ■ is the set vehicle speed ■. It is determined whether it is less than P2. This set vehicle speed voP2 has hysteresis and is, for example, 473 km/h.
is set to . When ■>■oP2, the process proceeds to the twelfth step L12, and when V≦VOP□, the process proceeds to the eighth step L8.

In the eighth step L8, the previous vehicle speed V is the set vehicle speed V.

, 2, and if V>VOP2, the timer t is activated at the ninth step L9. After resetting , the process proceeds to the 10th step LIO, and when ■≦VO1'2, the process proceeds to the 10th step L10. This 10th
In step LIO, it is determined whether or not the previous state was in an excitation state. If it was in a demagnetized state, the process advances to the sixth step L6, and if it was in the excitation state, the process advances to the eleventh step Lll.
And timer t. , is the setting timer t. , it is determined whether or not it exceeds 0, and if tol,>toPo, the process goes to the sixth step L6, and t. When l,≦topo, the process proceeds to the second step L2.

In the twelfth step L12, the engine rotation @N becomes the set rotation speed N. It is determined whether the number is less than 4.

This set rotation speed NEOP allows for hysteresis, and is set to, for example, 2500/2300 rpm. When NE≧NEOP, the process goes to the sixth step L6, and when Nc<NEOP. , the process proceeds to the thirteenth step L1.3.

In the 13th step L13, the intake pressure PR changes to the set intake pressure P.
It is determined whether or not it is less than EOP. This set intake pressure Pll0P has hysteresis, and is set to -100/-150 mmHg, for example. P
When R≧PEOr, the process goes to the 6th step L6, and when PB<PIIOF, the process goes to the 14th step L1.
Proceed to step 4.

In the fourteenth step L14, it is determined whether the throttle opening θTl+ is less than the set throttle opening θTHOP. This set throttle opening degree θT II OP is set to, for example, 20/15 d e g. θ
, 1. ≧θTl+. When the value is 1, the process proceeds to the 6th step L6, and when θTH<θTHOP, the process proceeds to the 15th step L1.
Proceed to step 5.

Further, in the fifteenth step L15, the throttle opening change rate Δθ□,I is positive and the set throttle opening change rate Δθ74.I is set with hysteresis. . It is determined whether or not it is less than 6, and 0<Δθ14. 〈ΔθT
When it is l1OP+, the process proceeds to the second step L2, and otherwise, the process proceeds to the sixth step L6.

To summarize such a procedure, it is determined in the third step L3 and the fourth step L4 that at high vehicle speeds exceeding 90/87 km/h, in a slow acceleration state where 0<Δθto<ΔθTl1OP2, the variable capacity turbo charger 5 is The movable vane 54 operates in a direction that increases the air gap circulation area between the movable vane 54 and the fixed vane 49. This makes it possible to prevent pumping loss.

In other words, when the vehicle is cruising at a high speed, acceleration is not required, and operating the movable vane 54 to increase the boost pressure will cause pumping loss due to the increase in back pressure caused by the high rotational speed of the engine. be.

Furthermore, in the fifth step L5, the solenoid 73 is demagnetized when the vehicle speed exceeds 65/63 km/h, but this is because the solenoid control valve 69 shown in FIG.
This is because control of is sufficient. Furthermore, the seventh step L
In steps Lll to 11th, the timer is reset when the vehicle is at a low speed of 4/3 km/h or less, that is, when the vehicle is almost stopped, and when the vehicle is at the previous speed or almost stopped, the solenoid is activated until the timer elapses, for example, 1 minute. 73 is excited to operate the movable vane 54 so that the flow area becomes larger. This is to prevent if the movable vane 54 is on the side that reduces the flow area at the time of restarting, the supercharging pressure P2 will temporarily rise and overload will be applied to the starting gear etc. . Furthermore, if the movable vane 54 is on the side that reduces the flow area when the vehicle speed is 4/3 km/h or less, it may cause the rotation of the variable capacity turbo charger 5 when it is rotating due to inertia etc. In this case, since the throttle opening degree θTH is almost fully closed, the supercharging pressure increases the internal pressure of the intake passage upstream of the throttle valve. Therefore,
By operating the movable vane 54 in a direction that increases the flow area, the occurrence of surging due to the pressure increase is prevented. Moreover, it can also contribute to the rise in catalyst temperature immediately after starting in a cold state.

Other 12th to 15th steps L12 to L15
According to the judgment conditions, VOP2 < V < VOPI,
NE < NEor, PR < P ROF, θ□
□〈θ7□. 2, O<ΔθTl+<Δθ11. . , when all of these conditions hold true, that is, in a slow acceleration state under partial load such as in 10-mode driving, the solenoid 73 is energized to lower the supercharging pressure P2, thereby preventing pumping loss. .

=58- In the above embodiments, a variable displacement turbocharger in which the capacity is changed by operating the movable vane 54 has been explained, but the present invention is applicable to a variable displacement turbocharger of a wastegate type and a boost pressure relief type. It is also applicable to chargers.

C0 Effects of the Invention As described above, according to the method of the present invention, target boost pressure and basic boost pressure control are performed when the engine speed changes from an accelerating state to a decelerating state under preset operating conditions of the engine. By reducing the amount, it is possible to detect a shift change based on the behavior of the engine speed and lower the boost pressure, thereby avoiding overshoot and achieving stable boost pressure control. can.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall schematic diagram showing the intake system and exhaust system of an internal combustion engine, FIG. 2 is a sectional view taken along the line ■-■, FIG. 4 is a sectional view taken along the IV-IV line in FIG. 2, FIG. 5 is a flowchart showing the main routine for controlling the electromagnetic control valve, and FIG. 7 is a graph showing the high boost pressure judgment guard value, FIG. 8 is a flowchart showing the basic duty at the 1st speed position and the target boost pressure subroutine, and FIG. 9 is a flow chart showing the subroutine for subtracting the target boost pressure. Fig. 8 is a diagram showing the discrimination zone used in the subroutine, Fig. 10 is a flowchart showing the subroutine for subtracting the basic duty and target boost pressure at positions other than the 1st speed position, and Fig. 11 is a subroutine for determining the set subroutine duty. A flowchart showing
Figure 12 is a diagram showing a map of the set subtraction duty.
3 is a flowchart showing a subroutine for determining the set addition duty, and FIGS. 14, 15, and 16.
The figure shows the setting map of DTRB, ΔP2ST, and ΔP2FB, respectively. Figure 17 is a flowchart showing a subroutine for determining the feedback coefficients related to the proportional control term and the integral control term. Figure 18 is a diagram showing the setting map of DTRB, ΔP2ST, and ΔP2FB. FIG. 19 is a diagram showing changes in duty and boost pressure at the time of transition from open loop control to feedback control, and FIG. 20 is a flowchart showing the main routine for controlling the electromagnetic on-off valve. . 5...Variable capacity turbocharger

Claims (1)

[Claims] The capacity of the variable displacement turbocharger is controlled based on the basic boost pressure control amount corresponding to the engine operating state, and
In a control method for a variable displacement turbocharger, the basic boost pressure control amount is corrected according to the deviation between the actual boost pressure and the target boost pressure when the operating state of the engine is in the feedback control region. A variable displacement turbocharger characterized in that the target boost pressure and the basic boost pressure control amount are reduced when the engine speed changes from an accelerating state to a decelerating state under preset operating conditions. control method.