JP2002221068A - Torque control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct accurately an excess or shortage of an engine torque in transient operation. SOLUTION: The target torque Tind is set in compliance with the engine load, and the presumed value of the current engine torque (presumptive torque) Tbase is calculated on the basis of the engine speed, air filling amount, etc. The deviation dT of the presumptive torque Tbase from the target torque Tind is subjected to a guard processing with the upper limit guard value and lower limit guard value as specified and cumulated, and the obtained cumulation is added to the presumptive torque Tbase, and thereby a corrected presumptive torque Tcal is determined in which a correction is made so that the presumptive torque Tbase approaches the target torque Tind. The engine torque is corrected by correcting the ignition timing, etc., in accordance with the deviation DT of the corrected presumptive torque Tcal from the target torque Tind. This allows accurate correction of the actual torque in excess or shortage with respect to the target torque Tind while the influence of the dispersion from system to system is excluded on the sesl time basis approximately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine torque control device having an improved engine torque control method.

[0002]

2. Description of the Related Art In engine control of a vehicle or the like, there is an engine control in which a target torque is set according to a driver's required torque (accelerator operation or the like) or an external load such as an air conditioner to control the engine torque. In this torque control system, a target air filling amount is set according to a target torque, and an air filling amount (a throttle opening, an ISC opening, etc.) is corrected according to a deviation between the target air filling and an actual air filling. By doing so, the actual engine torque is controlled to the target torque.

[0003] In an ideal torque control system, the target air filling amount and the actual air filling amount substantially coincide with each other during a steady operation with a small load change. However, in an actual system, variations due to individual differences of the system and changes over time are caused. As a result, a certain degree of deviation (deviation) occurs between the target air filling amount and the actual air filling amount even during steady operation. As disclosed in Japanese Patent No. 3044408, the deviation caused by the system variation is detected by being included in the deviation between the target air filling amount and the actual air filling amount even during the transient operation in which the engine load changes suddenly. Even when the torque is corrected in accordance with the deviation between the target air filling amount and the actual air filling amount during the transient operation, there is a possibility that a torque error corresponding to the deviation of the air filling amount due to system variation may occur.

Therefore, in Japanese Patent No. 3044408, as shown in FIG. 4, the deviation A between the target air filling amount and the actual air filling amount during a steady operation with a small load change [FIG.
Reference] is detected as a deviation due to system variation,
At the time of the transient operation in which the load change is equal to or more than a predetermined value, the air filling amount is determined according to the deviation [see FIG. By correcting the ignition timing and the ignition timing, the influence of system variations is reduced, and the accuracy of torque correction during transient operation is improved.

[0005]

Since the engine operating conditions such as the engine rotational speed change every moment, the deviation between the target air filling amount and the actual air filling amount due to system variation is not constant but changes every moment. . However, in the torque control disclosed in the above publication, during a period in which it is determined that the vehicle is in a transient state, the torque is corrected using a deviation due to a variation in the system detected during the immediately preceding steady state operation. The torque is not corrected in accordance with the excess or deficiency of the engine torque, which may lead to deterioration of fuel efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and accordingly, an object of the present invention is to accurately correct the excess or deficiency of the engine torque during transient operation, thereby improving the torque correction accuracy. It is an object of the present invention to provide a torque control device for an internal combustion engine, which is capable of performing the following.

[0007]

According to a first aspect of the present invention, there is provided a torque control device for an internal combustion engine which sets a target value of an engine torque (hereinafter referred to as a "target torque") according to an engine load. In addition to the setting by the target torque setting means, the estimated value of the actual engine torque (hereinafter referred to as “estimated torque”) is calculated by the estimated torque calculating means based on the parameters related to the engine torque. Then, the corrected estimated torque calculating means corrects the estimated torque based on the target torque and the estimated torque to obtain a corrected estimated torque, and the torque control means reduces the deviation based on the target torque and the corrected estimated torque. Control the engine torque in the direction of By doing so, during steady operation, the engine torque can be made to converge to the target torque, and the deviation between the two can be reduced to almost 0 (a state in which the variation in the system is canceled). During a transient operation in which the target torque changes, the corrected estimated torque can be made to follow the target torque with responsiveness corresponding to a deviation from the target torque.
Then, since the engine torque is corrected in a direction to reduce the deviation between the target torque and the corrected estimated torque, it is possible to deal with the excess or deficiency of the actual engine torque relative to the target torque while eliminating the influence of the system variation almost in real time. The torque correction can be performed, and the excess or deficiency of the engine torque during the transient operation can be accurately corrected.

In this case, when correcting the estimated torque based on the target torque and the estimated torque, the larger the correction amount of the estimated torque, the more quickly the corrected estimated torque can converge to the target torque during steady operation. However, if the correction amount of the estimated torque becomes too large, the deviation between the target torque and the corrected estimated torque during the transient operation becomes too small, and the torque correction amount during the transient operation becomes small. The accuracy may be reduced.

Therefore, when the estimated torque is corrected based on the target torque and the estimated torque,
It is preferable that the deviation between the target torque and the estimated torque is limited to a predetermined range by the guard means, and the estimated torque is corrected based on the limited deviation to obtain a corrected estimated torque. In this way, the deviation between the target torque and the corrected estimated torque during the transient operation can be appropriately secured while ensuring the convergence of the corrected estimated torque during the steady operation to the target torque. The amount can be appropriately secured, and the accuracy of torque correction during transient operation can be improved.

In an actual system, an actuator used for torque control has a response delay. Also,
To correct the torque in the intake system (for example, air charge),
The response delay of air to the operation of the actuator (for example, the throttle valve) is also relatively large. Such a response delay of the torque control system causes a response delay before a change in the target torque appears as a change in the estimated torque.

In consideration of this point, a corrected estimated torque is calculated based on the target torque and the current estimated torque at the time of going back in the past by the response delay time of the torque control system. It is good to do. If you do this,
Since the problem of the response delay between the target torque and the estimated torque used for calculating the corrected estimated torque can be solved, the corrected estimated torque can be accurately calculated without being affected by the response delay of the torque control system. High-precision torque control that is not affected by the response delay of the control system can be performed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine, and an air flow meter 14 for detecting an intake air amount is provided downstream of the air cleaner 13.
Is provided. Downstream of the air flow meter 14, a throttle valve 15 whose opening is adjusted by a motor (not shown) such as a DC motor is provided, and the opening of the throttle valve 15 (throttle opening) is determined by a throttle opening sensor. 16 detected.

Further, a surge tank 17 is provided downstream of the throttle valve 15.
7, an intake pipe pressure sensor 18 for detecting an intake pipe pressure is provided. In addition, the surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 is mounted near an intake port of the intake manifold 19 of each cylinder. Further, a spark plug 21 is attached to a cylinder head of each cylinder of the engine 11, and a water temperature sensor 2 for detecting a cooling water temperature is provided on a cylinder block of the engine 11.
2 and crank angle sensor 2 for detecting engine speed
3 is attached.

These various sensor outputs are input to an engine control circuit (hereinafter referred to as "ECU") 24.
The ECU 24 is mainly composed of a microcomputer, and executes various control programs stored in a built-in ROM (storage medium) to thereby control a fuel injection amount of the fuel injection valve 20 and a spark plug according to an engine operating state. 2
1 is controlled.

The ECU 24 executes the torque control program shown in FIG. 2 to calculate a target value of the engine torque (hereinafter referred to as "target torque") in accordance with the engine load, and to calculate the engine speed and the air charge amount. An estimated value of the actual engine torque (hereinafter referred to as “estimated torque”) is calculated based on the parameters related to the engine torque such as the above. Then, a deviation between the target torque and the estimated torque is subjected to guard processing with predetermined upper and lower guard values and integrated, and the integrated value is added to the estimated torque to calculate a corrected estimated torque. The engine torque is corrected so as to reduce the deviation between the engine torque and the target torque.

Hereinafter, specific processing contents of the torque control program of FIG. 2 executed by the ECU 24 will be described. This program is repeatedly executed at every predetermined time or every predetermined crank angle. When the program is started, first, in step 101, it is determined whether or not there is an abnormality in the control system based on various abnormality determination processing results. If it is determined that there is an abnormality, the subsequent torque control (step 10)
2 to 116), the program is terminated.

On the other hand, if it is determined in step 101 that there is no abnormality, the torque control process from step 102 is executed as follows. First, at step 102, the engine rotation speed Ne detected by the crank angle sensor 23 is read, and at next step 103, the air flow meter 1 is read.
The intake air amount Qa detected in step 4 is read. Thereafter, the routine proceeds to step 104, where the target torque Tind is set according to the engine operating parameters related to the engine load, such as the accelerator opening Acc, the engine speed Ne, the engine coolant temperature Thw, and the external load (for example, turning on / off the air conditioner). It is calculated using a map or the like. The processing of step 104 plays a role corresponding to the target torque setting means in the claims.

Thereafter, at step 105, the intake air amount Q
The air filling amount Maf is calculated by multiplying a value obtained by dividing a by the engine rotation speed Ne by a predetermined conversion constant K. Maf = K × Qa / Ne Then, in the next step 106, the engine rotation speed Ne
The estimated torque Tbase is calculated from a map or the like based on the air and the air filling amount Maf. The processing of step 106 plays a role corresponding to an estimated torque calculating means referred to in the claims.

Thereafter, the routine proceeds to step 107, where the target torque Tind (in) calculated a predetermined number of times (n times) corresponding to the response delay time of the torque control system and the estimated torque Tbase (i) calculated this time are used. Is calculated. dT = Tind (in) −Tbase (i) In this case, if the estimated torque Tbase is smaller than the target torque Tind, the torque deviation dT becomes a positive value. If the estimated torque Tbase is larger than the target torque Tind, the torque deviation dT becomes It becomes a negative value.

After calculating the torque deviation dT, step 108
Then, guard processing is performed on the torque deviation dT with predetermined upper and lower guard values to limit the torque deviation dT to a predetermined range. The processing in step 108 plays a role corresponding to a guard means in the claims. Then, in the next step 109, the current torque deviation dT is added to the torque deviation integrated value ΔT up to the previous time to update the torque deviation integrated value ΔT. ΔT = ΔT + dT

Thereafter, the routine proceeds to step 110, where a corrected estimated torque Tcal is obtained by adding the torque deviation integrated value ΔT to the estimated torque Tbase so that the estimated torque Tbase is corrected so as to approach the target torque Tind. Tcal = Tbase + [Delta] T The processing of steps 107 to 110 plays a role corresponding to a corrected estimated torque calculating means referred to in the claims.

After calculating the corrected estimated torque Tcal, the routine proceeds to step 111, where the target torque Tind and the corrected estimated torque Tca are calculated.
A corrected ignition timing is calculated in accordance with the torque deviation DT from the value l and an ignition signal is output to the ignition device of the ignition plug 21 in accordance with the corrected ignition timing in the next step 112.
The engine torque is corrected by such correction of the ignition timing.

After calculating the corrected estimated torque Tcal, the routine proceeds to step 113, where the air filling amount corrected according to the torque deviation DT between the target torque Tind and the corrected estimated torque Tcal is calculated. The engine torque may be corrected by driving the throttle valve 15 so as to adjust the air filling amount to the adjusted air filling amount. In a system equipped with an idle speed control valve (ISC valve), the air filling amount may be corrected by correcting the opening of the idle speed control valve.

After calculating the corrected estimated torque Tcal, the routine proceeds to step 115, where the fuel injection amount corrected in accordance with the torque deviation DT between the target torque Tind and the corrected estimated torque Tcal is calculated. The engine torque may be corrected by outputting an injection signal having a pulse width corresponding to the determined fuel injection amount to the fuel injection valve 20 and correcting the fuel injection amount.

The torque correction by correcting the ignition timing (steps 111 and 112), the torque correction by correcting the air charge (steps 113 and 114), and the torque correction by correcting the fuel injection amount (steps 115 and 116). Alternatively, two or three of the above may be combined. The processing of these steps 111 to 116 plays a role corresponding to the torque control means referred to in the claims.

A control example when the above-described torque control of the present embodiment is executed will be described with reference to a time chart of FIG. FIG. 3 shows an example of control in a case where the air conditioner, which is an external load, switches from an off state to an on state, and then switches back to an off state.

In the present embodiment, the estimated torque Tbase is corrected so as to approach the target torque Tind according to the torque deviation dT between the target torque Tind and the estimated torque Tbase (see FIG. 3B). Tcal is required. As a result, as shown in FIG. 3C, during a steady operation in which the target torque Tind is substantially constant, the actual engine torque (corrected estimated torque Tcal) is reduced to the target torque Tind.
In the transient operation in which the target torque Tind changes due to a change in the external load from this state, the corrected estimated torque Tcal is set to: It is possible to follow the target torque Tind with a response corresponding to the torque deviation DT from the target torque Tind.

Then, as shown in FIGS. 3E and 3F, the ignition timing and the like are corrected in accordance with the torque deviation DT between the target torque Tind and the corrected estimated torque Tcal to correct the engine torque. As a result, the target torque Tin can be eliminated while eliminating the influence of system variations almost in real time.
The excess or deficiency of the actual torque with respect to d can be accurately corrected.

In this case, when obtaining the corrected estimated torque Tcal by correcting the estimated torque Tbase so as to approach the target torque Tind side in accordance with the torque deviation dT, the larger the correction amount is, the larger the correction estimated during steady operation is. The torque Tcal can be quickly converged to the target torque Tind. However, if the correction amount is too large, the deviation between the target torque Tind and the corrected estimated torque Tcal becomes too small during the transient operation, and the torque during the transient operation is reduced. The correction amount may be small, and the accuracy of torque correction during transient operation may be reduced.

In this respect, in this embodiment, the torque deviation dT
Is calculated using a value limited by a predetermined upper guard value and a lower guard value, so that the convergence of the corrected estimated torque Tcal to the target torque Tind during steady operation is ensured. In addition, the deviation between the correction estimated torque Tcal and the target torque Tind can be appropriately secured during the transient operation, and the torque correction amount during the transient operation can be appropriately secured, thereby improving the torque correction accuracy during the transient operation. it can.

Incidentally, in an actual system, there is a response delay in an actuator used for torque control or the like. Particularly, when the torque is corrected in an intake system (for example, an air charge amount), the air flow with respect to the operation of the actuator (for example, the throttle valve 15). The response delay is relatively large. Such a response delay of the torque control system causes a response delay before the change in the target torque Tind appears as a change in the estimated torque Tbase.

In consideration of this point, in the present embodiment, the predetermined number of times (n times) corresponding to the response delay time of the torque control system.
Since the corrected estimated torque Tcal is calculated by comparing the previously calculated target torque Tind (in) with the currently calculated estimated torque Tbase (i), even if the torque control system has a response delay, The corrected estimated torque Tcal can be calculated by using the target torque Tind (in) which has solved the problem of the response delay and the estimated torque Tbase (i) calculated this time. As a result, the corrected estimated torque Tcal can be accurately calculated without being affected by the response delay of the torque control system, and highly accurate torque control not affected by the response delay of the torque control system can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of processing of a torque control program;

FIG. 3 is a time chart showing a control example of the embodiment.

FIG. 4 is a time chart showing a conventional control example.

[Explanation of symbols]

11: engine (internal combustion engine), 14: air flow meter, 15: throttle valve, 20: fuel injection valve, 21
... Spark plug, 22 ... Water temperature sensor, 23 ... Crank angle sensor, 24 ... ECU (target torque setting means, estimated torque calculation means, corrected estimated torque calculation means, torque control means,
Guard means).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/10 315 F02D 41/10 315 F02P 5/15 F02P 5/15 F F term (Reference) 3G022 FA04 GA01 GA05 GA06 GA07 GA09 3G065 CA13 DA05 DA15 EA04 EA05 FA06 FA07 FA12 GA00 GA01 GA05 GA09 GA10 GA37 GA46 HA21 HA22 JA04 JA09 JA11 KA02 3G084 BA02 BA05 BA06 BA13 BA17 DA05 DA25 EA04 EA11 EB08 EB12 EC02 EC03 FA07 FA31 FA18 FA33 LA00 LA03 LA04 LC03 MA11 NA04 NA08 NB02 NC02 ND01 NE17 NE19 PA01Z PA07Z PA17Z PE01Z PE03Z PE06Z PE08Z PF03Z PF13Z

Claims (3)

[Claims] 1. A target torque setting means for setting a target value of an engine torque (hereinafter, referred to as “target torque”) according to an engine load; and an estimated value of an actual engine torque (hereinafter, referred to as “target torque”) based on a parameter related to the engine torque. "Estimated torque")
Estimated torque calculating means for calculating the estimated torque, and correcting the estimated torque based on the target torque and the estimated torque to obtain a corrected estimated torque; based on the target torque and the corrected estimated torque And a torque control means for controlling the engine torque in a direction to reduce the deviation. 2. The method according to claim 1, wherein the correction estimated torque calculating means includes a guard means for limiting a deviation between the target torque and the estimated torque to a predetermined range, and a difference between the target torque and the estimated torque limited by the guard means. The torque control device for an internal combustion engine according to claim 1, wherein the estimated torque is corrected based on the deviation to obtain a corrected estimated torque. 3. The corrected estimated torque calculating means calculates a corrected estimated torque based on a target torque at a time preceding the response delay of the torque control system and a current estimated torque. The torque control device for an internal combustion engine according to claim 1 or 2, wherein: