JPH03229935A - Vehicular internal combustion engine control device - Google Patents

Abstract

PURPOSE:To make the intake air quantity appropriate so as to prevent the aggravation of emission by computing the manipulated variable of an intake air quantity limiting device according to the target torque of an internal combustion engine and the manipulated variable of a by-pass air quantity limiting device in regions other than a low load region, thus performing control. CONSTITUTION:On the basis of the accelerator manipulated variable detected by a means (a), the manipulated variable equivalent value is computed by a means (d) according to the target torque computed by a means (c). Also on the basis of the rotating speed detected by a means (b), the above-mentioned manipulated variable equivalent value is corrected by a means (f) according to the manipulated variable computed by a means (e). Further on the basis of the above-mentioned correction value, an intake air quantity limiting device is controlled by a means (g), as well as a by-pass air quantity limiting device is controlled by a means (h) on the basis of the above-mentioned manipulated variable. On the other hand, the final fuel supply quantity is determined by a means (l) according to the first fuel supply quantity computed by a means (i) on the basis of the target torque and the second fuel supply quantity computed by a means (k) on the basis of the intake air quantity detected by a means (j), and this fuel is supplied by a means (m).

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device for a vehicle internal combustion engine that controls a device that limits the amount of intake air by servo-controlling the device.

<Prior art> As a conventional control device for a vehicle internal combustion engine,
As shown in Publication No. 155235, the mainstream method was to detect the intake air amount and determine the fuel supply amount and ignition timing according to this intake air amount (air amount-driven method).
This method cannot provide the optimum amount of fuel because there is a delay in detecting the amount of intake air in response to the amount of air that changes from time to time during transient operating conditions.

On the other hand, as shown in Japanese Patent Application No. 63-144797, there is a method (torque-driven method) in which the fuel amount and air amount are determined using the engine output shaft torque, which is a physical quantity that directly affects vehicle control, as the reference amount for control. Proposed.

That is, the target value of the engine output shaft torque is set from the accelerator operation amount and the engine rotation speed, and the amount of fuel supplied from the fuel injection valve is controlled according to the target torque, and the throttle valve opening is controlled by the actuator. This controls the amount of intake air. With this method, the problem of delay in intake air amount detection in the air amount-driven method does not occur.

<Problems to be Solved by the Invention> By the way, in the conventional control device for a vehicle internal combustion engine that adopts the torque-driven method described above, in order to integrally control the amount of fuel and the amount of air, it is difficult to control the amount of intake air. Metering depends on throttle valve opening control.

However, in low load areas, throttle valve opening control alone cannot control the air flow rate due to the amount of bypass air from the bypass passage provided by bypassing the throttle valve for idle control, etc., and the influence of air leakage from the throttle valve. Weighing accuracy cannot be ensured.

Furthermore, even if the bypass passage is fully closed and the bypass air amount is controlled to O in operating ranges other than low load ranges, if the throttle valve is suddenly operated, such as when stepping on the accelerator from idle, for example for,
The actual air flow rate increases compared to the target air flow rate by the delay in bypass air flow due to the response delay of the bypass control valve, causing the air-fuel ratio to shift to the lean side, resulting in worsening of emissions.
Drivability deteriorated due to misfires, etc.

The present invention was developed in view of the conventional circumstances, and employs an air-driven method based on air amount detection in low-load regions where throttle valve control is difficult, and a torque-driven method in other regions. It is an object of the present invention to provide a control device for a vehicle internal combustion engine that solves the above-mentioned problems by correcting intake air commensurate with the amount of bypass air during a transition between the two states.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention comprises: accelerator operation amount detection means a for detecting the accelerator operation amount; a target torque calculation means C that calculates a target torque of the engine based on the detected accelerator operation amount; and calculates a value equivalent to the operation amount of a device that limits the amount of intake air to the engine according to the calculated target torque. an intake air amount limiting device operation amount equivalent value calculation means d to calculate the amount of operation of the device that limits the amount of bypass air that passes through a passage that bypasses the device that limits the amount of intake air to the engine, based on the engine operating conditions. a bypass air amount limiting device manipulated variable calculation means e that calculates the bypass air amount limiting device manipulated variable, and an intake air amount limiting device manipulated variable equivalent value correction device that corrects the intake air amount limiting device manipulated variable equivalent value based on the bypass air amount limiting device manipulated variable. f, an intake air amount limiting device control means g that controls the intake air amount limiting device based on the corrected intake air amount limiting device operating amount equivalent value, and based on the calculated bypass air amount limiting device operating amount. bypass air amount limiting device control means for controlling a bypass air amount limiting device that limits the amount of bypass air; and first fuel supply amount calculation means i for calculating a first fuel amount based on the calculated target torque. , an intake air amount detection means j for detecting the intake air amount of the engine, and a second fuel supply amount calculation means for calculating a second fuel supply amount based on the detected intake air amount; Determining the final fuel supply amount by selecting the first fuel supply amount as the final fuel supply amount when the load is not low, and selecting the second fuel supply amount when the load is low, according to the engine rotational speed and the calculated target torque. The fuel supply device M includes: means J; and fuel supply means m for supplying fuel to the engine based on the determined final fuel supply amount.

<Operation> The target torque calculation means C calculates the target torque TRO of the engine based on the accelerator operation amount Acc detected by the accelerator operation amount detection means a.

The intake air amount limiting device operation amount equivalent value calculating means d is a device (for example, a throttle valve and its driving mechanism) that limits the amount of intake air to the engine according to the calculated target torque TR0.
An equivalent value θ'' (throttle valve opening degree) corresponding to the manipulated variable (for example, the passage area of a device that limits the amount of intake air) is calculated.

The bypass air amount limiting device operation amount calculating means e calculates the amount of operation (ISO valve (opening degree) is calculated based on, for example, the engine rotation speed N.

The intake air amount limiting device manipulated variable equivalent value correcting means f corrects the calculated intake air amount limiting device manipulated amount equivalent value θ'' based on the bypass air amount limiting device manipulated variable ■ to limit the intake air amount. Obtain the device operation amount correction value θ.

Then, the intake air amount limiting device control means g controls the intake air amount limiting device based on the obtained intake air amount limiting device operation amount correction value θ, and the bypass air amount limiting device control means g controls the intake air amount limiting device based on the obtained intake air amount limiting device operation amount correction value θ. The bypass air amount limiting device that limits the amount of bypass air is controlled based on the computed bypass air amount limiting device operation amount ■.

On the other hand, regarding the fuel supply amount, the first fuel supply amount calculation means i calculates the first fuel supply amount based on the calculated target torque TRO.
Calculates the fuel supply amount Ti, and also calculates the intake air amount detection means j
Based on the intake air amount Q of the engine detected by
The fuel supply amount calculation means k calculates the second fuel supply amount Ti'.

Then, the final fuel supply amount determining means 1 determines the first fuel supply amount as the final fuel supply amount according to the detected engine rotational speed N and the calculated target torque TRO.
The fuel supply amount Ti is selected, and the second fuel supply amount Ti' is selected when the load is low.

Based on the determined final fuel supply amount, the fuel supply means m supplies fuel to the engine.

Therefore, in the low load region, control is performed based on the detected intake air amount Q, and in other regions, control is performed according to the engine target torque TR6 and the operating amount ■ of the device that limits the bypass air amount. .

<Example> An embodiment of this invention will be described below based on the drawings.

In FIG. 2 showing the system configuration of this embodiment, an internal combustion engine 1 includes an air cleaner, an intake duct 2. Air is drawn in via the throttle chamber 3 and the intake manifold 4. The throttle chamber 3 is provided with a throttle valve 5 as an intake air amount limiting device.
Controls the main air volume. Further, the throttle chamber 3
A bypass passage 6 is provided to bypass the throttle valve 5, and the bypass passage 6 is provided with an ISC valve 7 as a bypass air amount limiting device to control the amount of bypass air.

The accelerator opening sensor 21 detects the accelerator opening (accelerator operation amount) ACC based on the output voltage of the potentiometer. Note that the accelerator opening sensor 21 constitutes accelerator operation amount detection means a.

The crank angle sensor 22 outputs a signal for each minute unit angle of the crank angle and a signal for each reference position. Incidentally, since the engine rotational speed N is detected based on this signal, the crank angle sensor 22 constitutes rotational speed detection means.

An intake pressure sensor 2a is provided in the intake manifold 4 downstream of the throttle valve 5, and detects the intake pressure PB.

Further, the actual throttle valve opening θ of the throttle valve 5
7 and the actual ISCSC pulp vR of the ISC valve 7, a throttle sensor 24 and an ISC valve opening detection sensor 25 are provided.

Furthermore, a water temperature sensor 26 that detects the temperature of the cooling water, an air conditioner switch 27, and a battery sensor 28 that detects the voltage of the battery are provided.

Then, the detection signals from the sensors 21 to 28 described above are input to the CPU 31 of the microcomputer, and the CPU 31 performs the operations shown in FIGS. A throttle valve opening command value θ and an ISCSC pulp command value V are calculated based on the following, and the command values θ and 1 are output to the throttle valve drive device 8 and ISC valve drive device 9.

Here, the throttle valve driving device 8 controls the opening of the throttle valve 5 according to the deviation between the actual throttle valve opening θ8 detected by the throttle sensor 24 and the throttle valve opening command value θ input from the CPU 31. The angle is made to follow the command value θ. Similarly, the rsc pulp driving device 9 controls the actual ISCSC pulp 8 detected by the ISC valve opening detection sensor 25 and the ISC pulp driving device 9.
The opening degree of the ISC valve 7 is made to follow the command value V according to the deviation from the valve opening command value V.

The CPU 31 also controls the fuel injection amount based on the detected engine intake air amount Q and engine rotational speed N when the load is low, and according to the engine rotational speed N and the target torque TRO when the load is not low. A fuel injection pulse having a pulse width corresponding to the calculation is outputted to the fuel injection valve IO provided in the intake manifold 4 to perform fuel supply control.

Further, the CP 031 outputs an ignition signal to the ignition coil 11 at the set ignition timing based on the signal from the crank angle sensor 22.

The control operations performed by the CPU 31 will be explained according to the flowcharts shown in FIGS. 3 to 5. The main routine shown in FIG. 3 is executed at regular intervals (for example, every 10 m5).

In step (denoted as S in the figure, the same applies hereinafter) 31, the accelerator opening degree (accelerator operation amount) ACC is read from the accelerator opening degree sensor 21.

In step 32, the engine rotational speed N is calculated based on the signal for each minute unit angle from the crank angle sensor 22.

In step 33, the intake pressure PB is measured based on the signal from the intake pressure sensor 23, and the intake air amount Q is calculated using the following equation.

Q=to-PB However, K is a constant determined by the characteristics of the engine. That is, the portion of step 33 and the intake pressure sensor 23 constitute the intake air amount detection means j.

In step 34, it is determined whether or not the internal combustion engine 1 is in a region where idle rotational speed feedback control is performed.

That is, when the accelerator opening degree ACC1, engine rotational speed N, and intake pressure PB are each below a predetermined value, it is assumed that the idle rotational speed is in a region where feedback control is performed (hereinafter referred to as a low load region), and the process proceeds to step 36, where the subroutine is executed. 2 is executed, and if it is determined that the area is other than the low load area, the process proceeds to step 35 and subroutine 1 is executed.

Here, subroutine 1 will be explained based on FIG.

In step 41, target torque TRO is calculated.

TRO is the torque required for the vehicle operating conditions at that time, and is given according to the vehicle operating conditions. Incidentally, if there is no need to change the characteristics according to the driving conditions of the vehicle, it is possible to simply obtain the output torque characteristics from the accelerator opening degree ACC by searching or the like according to the output torque characteristics set in the torque table. In this step 41, the function of the target torque calculation means C is fulfilled.

In step 42, the intake air passage opening area S required to achieve the target torque is calculated from the engine rotational speed N and the target torque 4T Ro. Specifically, it is determined by searching or the like using a table of intake air passage opening area S assigned to engine rotational speed N and target torque TRe.

In step 43, the ISCSC pulp command value V is set. That is, the opening degree command value is gradually decreased from the final value set in a routine described later until it reaches 0 according to the elapsed time or the cumulative number of rotations.

In step 44, the actual ISCSC pulp (2) is detected from the output of the ISC valve opening detection sensor 25. Furthermore, I
When the SC valve driving device 9 uses a step motor, a duty control valve, etc., the actual ISCSC pulp VR may be calculated using the ISCSC pulp command value ■.

In step 45, from the actual ISCSC pulp ■3,
The opening area S of the bypass passage 6 is calculated.

Specifically, a table showing the relationship between the ISCSC pulp ■8 and the opening area Sb as shown in FIG. 6 is prepared in advance, and the table is read out from the ISCSC pulp ■7.

That is, steps 44 and 45 fulfill the function of the bypass air amount limiting device manipulated variable calculation means e.

In step 46, the throttle valve opening area S is calculated from the intake air passage opening area S and the opening area Sb according to the following formula.

S, = S - S.

In step 47, a throttle valve opening command value θ is calculated from the throttle valve opening area S5. in particular,
A table showing the relationship between the throttle valve opening area SS and the throttle valve opening command value θ as shown in FIG. 7 is prepared in advance, and is read from the throttle valve opening area S5. Here, this throttle valve opening command value θ is the actual ISC
Since the value is corrected by the opening area Sb of the bypass passage 6 calculated from SC pulp ■, that is, the amount of bypass air, the target value is determined by both the amount of main air passing through the throttle chamber 3 and the amount of bypass air. Torque TRO
It is possible to secure an amount of intake air equivalent to .

That is, the function of step 42 corresponds to the intake air amount limiting device 6 manipulated variable equivalent value calculation means d, and the functions of steps 43 to 47 correspond to the intake air amount limiting device manipulated amount equivalent value correction device f.

Next, in step 48, a fuel injection pulse Ti is calculated. Specifically, the basic fuel injection pulse Tp is read out from the target torque T'+to and the engine rotational speed N by referring to a fuel injection pulse table. The data here is also determined from the performance of the engine installed in the vehicle.

Various corrections are made to the basic fuel injection pulse TP depending on the operating state of the engine (increase correction according to cooling water temperature, increase correction at startup, air-fuel ratio feedback correction based on the detected value of oxygen concentration in the exhaust gas). etc.) (correction coefficient C) to calculate the fuel injection pulse Ti.

That is, the function of step 48 is the first fuel supply amount calculating means i.
corresponds to

Next, based on FIG. 5, subroutine 2 that is executed when it is determined that the idle rotation speed is in a region where feedback control is performed (hereinafter referred to as a low load region) will be described.

In step 51, the throttle valve opening command value θ is calculated, but since this subroutine 2 is a routine that is executed when the idle speed feedback control is performed, the intake air control is controlled by the ISC valve 7.
Therefore, the throttle valve opening command value θ is calculated so that the throttle valve 5 is fully opened.

In step 52, the target rotation speed N is determined based on the coolant temperature detected by the water temperature sensor 26, air conditioner switch 27, and battery sensor 28, the operating state of the air conditioner, and the battery voltage.
Set 0 by search or calculation.

In step 53, the engine rotation speed N and the target rotation speed N
. The difference is calculated and assigned to the variable NvAR.

In step 54, in order to obtain the integral of the rotational difference, the sum of the variable (rotational integral) old data NVAROLD and NVAR is calculated as NVARNEII+.

Further, the integral obtained by multiplying the integral NVARNEW by a constant KI and the proportional bone obtained by multiplying the variable NVAR by a constant KP are added to obtain the proportional/integral constant N p + of the rotation difference according to the following formula.

NFl= K I X NVAII NEW + K
P. That is, V=KbXN□ That is, step 55 also fulfills the function of the bypass air amount limiting device manipulated variable calculation means e.

In step 56, a basic fuel injection pulse Tp is first calculated based on the intake air amount Q (=K - PB) calculated in step 33 and the engine rotational speed N.

Various corrections are made to the basic fuel injection pulse Tp depending on the operating state of the engine (increase correction according to the cooling water temperature, increase correction at startup, air-fuel ratio feedback correction based on the detected value of oxygen concentration in the exhaust gas). (correction value C) to calculate the fuel injection pulse Ti.

9 That is, the function of step 56 is performed by the second fuel supply amount calculation means k.
corresponds to

As explained above, in regions other than low load (non-idling), both the main air amount passing through the throttle chamber 3 and the bypass air amount are considered until the bypass air amount becomes 0. to secure the intake air amount corresponding to the target torque TRO, and further calculate the fuel injection pulse Ti.In the low load region (idling), the fuel injection amount is calculated based on the intake air amount Q determined from the intake negative pressure. , and perform feedback control of the idle rotation speed.

In this embodiment, the bypass air amount is finally set to O during non-idling, but the bypass air amount is not limited to this, and may be maintained at the final value during idling, for example. In this case as well, the main air amount may be set in consideration of the bypass air amount.

In step 37, step 47 in the subroutine
The throttle valve opening command value θ calculated in step 51 or the throttle valve opening command value θ calculated in step 51 is output to the throttle valve driving device 8. As a result, the throttle valve 5 is feedback-controlled to match the throttle valve opening command value θ.

That is, the throttle sensor 24. Throttle valve drive device 8
The function of step 37 also corresponds to the intake air amount limiting device control means g.

In step 38, step 48 in the subroutine
Alternatively, the fuel injection pulse Ti calculated in step 56 is set to the output port of the CPU 31. As a result, a fuel injection pulse Ti having a pulse width of Ti is outputted to the fuel injection valve 10 at a predetermined timing triggered by a crank angle signal from the crank angle sensor 22, and fuel is injected and supplied.

That is, the function of step 38 is the final fuel supply amount determining means I.
, and the function of step 38 and the fuel injection valve 1
Hardware such as 0 corresponds to the fuel supply means m.

In step 39, step 44 in the subroutine
Alternatively, the opening command value ■ of the ISC valve 7 calculated in step 55 is output to the ISC valve driving device 9. As a result, the ISC valve 7 is feedback-controlled to match the command value V1.

That is, the step 390 function is performed by the ISC valve opening detection sensor 25. Together with the ISC valve drive device 9, it corresponds to the bypass air amount limiting device control means.

Therefore, as explained above, according to this embodiment, the CPU
31, when the throttle valve opening command value θ and the SCSC pulp command value V are calculated, as shown in FIG. 8, the time t is reached from the idle state. When the accelerator is depressed from time t to time t, the throttle valve opening command value θ is corrected based on the actual ISCSC pulp 7. Therefore, even if air is sucked through the bypass passage 6 during this period, the target torque T is maintained due to both the main air amount passing through the throttle chamber 3 and the bypass air amount passing through the bypass passage 6.
The amount of intake air corresponding to R0 can be secured.

Therefore, the amount of intake air becomes an appropriate value, and drivability becomes good.

<Effects of the Invention> As explained above, according to the present invention, control is performed based on the detected intake air amount in the low load region2, and the engine target torque and bypass air amount are limited in other regions. The amount of operation of the device that limits the intake air amount to the engine is calculated and controlled according to the amount of operation of the device that limits the intake air amount to the engine, so the amount of intake air becomes an appropriate value, thereby preventing deterioration of emissions. It is also possible to prevent deterioration in drivability due to misfires and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system configuration diagram of an embodiment according to the present invention, FIGS. 3 to 5 are flowcharts showing control operations in the above embodiment, and FIG. I
FIG. 7 is a characteristic diagram of the valve opening degree θ of the SC valve and the opening area S of the bypass passage, and FIG. 7 is a characteristic diagram of the valve opening degree θ of the throttle valve and the opening area S3 of the main passage.
The figure is a time chart according to the same embodiment. 1... Internal combustion engine 5... Throttle valve 7...
・ISC valve 10...Fuel injection valve 21...
・Accelerator opening sensor 22... Crank angle sensor 23... Intake pressure sensor 24... Throttle sensor 25... I3 SC valve opening detection sensor 31... CPU

Claims (1)

[Scope of Claims] Accelerator operation amount detection means for detecting an accelerator operation amount; rotation speed detection means for detecting the engine rotation speed; and a target for calculating a target torque of the engine based on the detected accelerator operation amount. a torque calculation means; an intake air amount limiting device operation amount equivalent value calculation means for calculating an operation amount equivalent value of a device that limits the intake air amount to the engine according to the calculated target torque; a bypass air amount limiting device operation amount calculation means for calculating an amount of operation of the device that limits the amount of bypass air passing through a passage that bypasses the device that limits the amount of air, based on engine operating conditions; and the bypass air amount limiting device. an intake air amount limiting device operation amount equivalent value correction means for correcting the intake air amount limiting device operation amount equivalent value based on the operation amount; Intake air amount limiting device control means for controlling the limiting device; Bypass air amount limiting device control means for controlling the bypass air amount limiting device for limiting the bypass air amount based on the calculated bypass air amount limiting device operation amount. , a first fuel supply amount calculation means for calculating a first fuel supply amount based on the calculated target torque; an intake air amount detection means for detecting an intake air amount of the engine; a second fuel supply amount calculation means for calculating a second fuel supply amount based on the detected engine speed and the calculated target torque; a final fuel supply amount determining means that selects one fuel supply amount and selects a second fuel supply amount when the load is low; and a fuel supply means that supplies fuel to the engine based on the determined final fuel supply amount. A control device for a vehicle internal combustion engine, comprising: