JPS6054005A - On-vehicle electronic feedback controller - Google Patents

Abstract

PURPOSE:To perform a stable feedback control having a high following-up capacity by resetting a proportional constant and an integral constant to prescribed initial values if the deviation quantity between a target value and an actual value exceeds a prescribed value. CONSTITUTION:The output signal from a CPU1 is sent to a fuel injection valve 22 through a current waveform circuit 21. The CPU1 compares a feedback correction quantity alpha with a prescribed value; and if the quantity alpha is smaller, it is judged that the control advances, and the value of the update number of a learning correction coefficient alpha0 is increased by one. Meanwhile, if the correction value alpha is larger than the prescribed value, it is judged that the difference between an air-fuel ratio and a logical air-fuel ratio is large, and the value of the updata number is reset to zero, and values of the proportional constant and the integral constant of PI control are reset to initial values having prescribed sufficiently large values. Thus, the proportional plus integral control action is performed with a large control constant to improve the following-up capacity of the air-fuel ratio to the logical air-fuel ratio.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to a vehicle-mounted electronic feedback control device that determines a shift feedback correction amount by proportional-integral control. It relates to something that has a function that can be changed accordingly.

<Background Art> As this type of feedback control device, there is, for example, one used for air-fuel ratio feedback control of an electronically controlled fuel injection type internal combustion engine.

To explain this, in an electronically controlled fuel injection type internal combustion engine, the fuel injection amount Ti (valve opening pulse width for driving the fuel injection valve) is determined by the following equation.

Ti -'rp X C0EF Xα ten T8 here,'
rp is the basic injection amount and is expressed as Tp - K x Q/N, where K is a constant, Q is the intake air flow rate, and N is the engine rotation speed. C0KF is a correction coefficient determined depending on various operating conditions, and α is a feedback correction coefficient for air-fuel ratio feedback control (hereinafter referred to as λ control), which will be described later. Further, Ttz is a voltage correction amount, which is for correcting fluctuations in battery voltage.

λ control detects the actual air-fuel ratio by installing an O2 sensor in the exhaust system, and uses the slice level to determine whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio. The amount of fuel injected is controlled so that the air-fuel ratio is maintained.For this purpose, the above-mentioned air-fuel ratio feedback correction coefficient α is determined, and by changing α, the stoichiometric air-fuel ratio can be maintained. It is intended to enable

Here, the value of the air-fuel ratio feedback correction coefficient α is changed by proportional-integral control (PI control) to achieve stable control.

In other words, the output of the 0□ sensor is compared with the slice level, and the output of the 02 sensor is larger than the slice level (
If the air-fuel ratio is rich (lean), do not suddenly make the air-fuel ratio lean (rich), but first lower (raise) it by an amount outside of proportionality (hereinafter referred to as P), then calculate the integral ( Below 1
decrease (increase) the air-fuel ratio in increments of
darken).

However, in a region where λ control is not performed, the α-reduction is clamped to 1, and a desired air-fuel ratio is obtained by setting various correction coefficients COEF.

By the way, the air-fuel ratio obtained when α is set to 1 in the λ control region, that is, the base air-fuel ratio, is the stoichiometric air-fuel ratio (λ-
If it is possible to set 1), feedback control is not necessary, but in reality, there are variations in component parts (for example, air flow meter, fuel injection valve, flare regulator, control unit), changes over time, and pulse width of the fuel injection valve. Because the base air-fuel ratio deviates from λ = 1 due to factors such as nonlinearity of convective flow characteristics and changes in operating conditions and environment, the value of α is changed by proportional-integral control as described above. Feedback control is performed so that the value becomes -1.

However, the deviation of the base air-fuel ratio from λ-1 differs depending on the operating region. In other words, the value of α to obtain λ = 1 differs depending on the operating region, so if this difference is large, the deviation from the operating region When λ changes, the air-fuel ratio is controlled by feedback control.
It takes time to settle to -1.

As a result, the three-way catalyst is operated at an air-fuel ratio with poor conversion efficiency.In addition to increased costs due to an increase in the amount of precious metal in the catalyst, the conversion efficiency is further deteriorated due to deterioration of the catalyst. A problem arises in that replacement is forced.

Therefore, a learning correction coefficient α0 is introduced so that the air-fuel ratio when α-1, that is, the base air-fuel ratio, becomes λ-1.
Learning correction is performed so that 0 becomes λ-1 when α-1 in each operating state. This reduces the step in the base air-fuel ratio due to changes in the operating state, shortens the period in which the air-fuel ratio deviates from λ = 1, and performs proportional-integral control to determine the value of α. A learning control device for the base air-fuel ratio has been devised to improve controllability by making it possible to reduce the value of P/I in , and to reduce the cost of the catalyst.

That is, for example, a map of learning correction coefficient α0 having a value such that the base air-fuel ratio corresponding to engine operating conditions such as engine speed and load is λ-a1 is stored on data storage means such as RAM of a microcomputer. When calculating the injection amount TI, the injection amount 'rp is corrected as shown in the following equation.

Ti −Tp X C0EFXα×αo+Ts where,
The learning of α0 proceeds in the following steps.

1) Engine operating conditions and α in steady state
and detect.

11) Search for α0 that has been learned and stored up to now in accordance with the engine operating conditions.

111) Add the value of α0+Δα/M to α0 and update the memory using the result as new α0.

Note that △α indicates the amount of deviation from the reference value α1, and △α=α
-αl, the reference value α1 is generally equal to 1.0. Moreover, M is a constant.

By the way, when adopting such a learning control device,
If the P/I component for determining the value of α is made small from the beginning, the transient response will deteriorate before learning progresses, that is, before the base air-fuel ratio reaches λ-i. . Conversely, learning progresses and the base air-fuel ratio becomes λ=
1, if λ control is performed with a large P/I, the air-fuel ratio will fluctuate around λ-1, causing rotational speed fluctuations, etc.

An invention to avoid these problems has been made by the applicant of the present invention (Japanese Patent Application No. 58-076224), which will be explained with reference to the flowchart shown in FIG.

That is, the learning control is performed in 5101, and the learning control is performed in 5102.
The learning correction coefficient α0 updated in step 5103 is stored in the RAM, and the number of updates (learning number) C of α0 is counted up in step 5103. Then, the next time the four-gram is activated, in 8104 of the learning control routine 8101, it is determined whether the number of updates of α0 has reached a predetermined value, and if it is greater than or equal to the predetermined value, learning progresses. are doing(
It is determined that the air-fuel ratio λ is close to 1), and the process proceeds to 5105.
Decrease the value of PI sub-control P/I for determining.

On the other hand, if the number of updates C of α0 is less than a predetermined value, it is determined that learning is not progressing, and the P/I reduction process 5
Bypass 105. However, along with the learning correction coefficient α0, P/1. The value of the minute is also modified according to the progress of the learning capacity control.

In this way, controllability is improved by reducing the P/I portion of the air-fuel ratio feedback correction coefficient α in the PI sub-control according to the progress of learning, but if the system suddenly changes (for example, the vehicle When a person enters a mountainous area and the temperature, pressure, etc. suddenly decrease), it is necessary to correct (learn) the learning correction coefficient α0 accordingly, but it takes a certain amount of time for this to occur. do. Therefore, during this time α is 1
The air-fuel ratio will be kept at λ-1 by making a large change from This has disadvantages in that it takes time to reach the desired value and the ability to follow sudden changes in the system is reduced.

This is not limited to air-fuel ratio control as described above, but also applies to electronic feedback control devices installed in vehicles that determine the feedback correction amount using proportional-integral control and reduce the proportional and integral constants as the control progresses. This is an inconvenience that generally occurs when the amount of deviation between the controlled variable and the target value suddenly increases.

<Purpose of the Invention> The present invention has been made in view of the above-mentioned problems of the prior art, and provides a stable and followable electronic feed puncture control device installed in a vehicle that determines the feedback correction amount by proportional-integral control. It is an object of the present invention to provide a control device that determines a proportional constant and an integral constant in the proportional-integral control so that feedback control with good performance is exerted.

<Summary of the Invention> To this end, the present invention provides a means for determining a feedback correction amount for making a controlled variable follow a target value by proportional-integral control, as shown in FIG. A vehicle-mounted electronic feedback control device comprising means for decreasing the value of a constant according to the progress of control, comprising means for detecting a deviation amount between a target value and an actual value of the control variable; To achieve the above object, a control device is provided with means for resetting the values of the proportionality constant and the integral constant to predetermined initial values when the detected deviation amount exceeds a predetermined value.

<Example> The present invention will be described below based on an example shown in FIG. Note that this is an application of the present invention to the air-fuel ratio feedback control of the aforementioned electronically controlled fuel injection type internal combustion engine.

Configuration: In the figure, 1 is CPU, 2 is P-ROM1
3 is an OMO8-RAM for learning control, and 4 is an address decoder. In addition, for RAM3, key switch O
A backup power supply circuit is used to retain the memory contents even after FF.

Analog input signals to the CPU 1 for fuel injection amount control include an intake air flow rate signal from the hot wire air flow meter 5, a throttle opening signal from the throttle sensor 6, a water temperature signal from the water temperature sensor T, and a 02 sensor. The exhaust oxygen concentration signal from 8 and the battery voltage from battery 9 are inputted via an analog input interface 10 and an A/D converter 11.

12 is an A/D conversion timing controller.

Digital input signals include ON/OFF signals from the idle switch 13, start switch 14, and neutral switch 15, and these are inputted via the digital input interface 7ace 16.

In addition, for example, 180° from the crank angle sensor 17
A seven-alignment signal for every angle and a position signal for every 1° are inputted via a one-shot multi-circuit 18. Further, a vehicle speed signal from a vehicle speed sensor 19 is inputted via a waveform shaping circuit 20.

The output signal from the CPUI (drive pulse signal to the fuel injection valve) is sent to the fuel injection valve 22 via the current waveform control circuit 21.
It is now sent to

Operation Next, the operation of this device will be explained according to the flowchart shown in FIG.

The basic injection amount Tp is determined from the intake air flow rate Q obtained from the signal from the air flow meter 5 at Sl and the engine rotation speed N obtained from the signal from the crank angle sensor 17.
(=KXQ/N) is calculated.

A correction coefficient C0EF determined from various operating conditions is set in Sl.

In S3, the number of updates C of the learning correction coefficient α0 (81G
If the value is greater than or equal to the predetermined value, it is determined that the control is progressing, the count value C is cleared in S4, and the P/I value for determining α is After decreasing by a predetermined amount, the process proceeds to S6. On the other hand, if it is less than the predetermined value, the PZI portion is not changed and the process is performed as it is in S6.
Proceed to.

That is, step S5 corresponds to the control constant reduction correction means shown in FIG.

In S6, the output from the 02 sensor 8 is compared with the slice level, and the υ air-fuel ratio feedback correction coefficient α is set by proportional-integral control based on the p/I component. This process S
6 corresponds to the feedback correction amount determining means in FIG.

In S7, a voltage correction numerator Il is set based on the battery voltage from the battery 9.

In S8, engine rotation speed N and basic injection amount (load) T
The learning correction coefficient αO is searched from p. In addition, the rotation speed N
A map of the learning correction coefficient α0 with respect to the basic injection amount Tp is stored in the rewritable RAM 3, and is all αO-1 at the time when learning has not started.

Furthermore, this map has approximately N=8 lattices and Tp-4 lattices.

89 to 812 are provided to detect a steady state. In S9, a change in vehicle speed is determined based on the signal from the vehicle speed sensor 19, and in S10, the gear position is determined based on the signal from the neutral switch 15. Then, in S11, a change in the throttle opening degree is determined based on the signal from the throttle sensor 6, and in 812, it is determined whether a predetermined time has elapsed, and if it is within the predetermined time, the process returns to S9. In this way, if the change in vehicle speed is less than a predetermined value within a predetermined time, the gear is engaged, and the change in throttle opening is less than a predetermined value,
It is determined that the state is steady, and the learning correction coefficient α0 is corrected at 813.814.

The correction of the learning correction coefficient α0 in 813 when it is determined that the steady state
This is done based on the formula +Δα/M.

In S14, a new learning correction coefficient α0 is written to the corresponding engine rotational speed N and basic injection amount Tp in the RAM 3. That is, the data in RAMa is updated.

At 815, the feedback correction amount α is compared with a predetermined value, and α
is smaller than a predetermined value, it is determined that the control is progressing (the air-fuel ratio is approaching the stoichiometric air-fuel ratio λ-1), and S1
Proceed to step 6 and increase the value of the number of updates C of α0 by 1.

On the other hand, if α is larger than the predetermined value, it is determined that the difference between the air-fuel ratio and the stoichiometric air-fuel ratio is large, and the value of the number of updates C is reset to zero in 817, and the proportional constant and integral of the PI control are The value of the constant is reset to an initial value having a predetermined sufficiently large value.

That is, this process S17 corresponds to the control constant reset means shown in FIG.

As a result, even if the deviation between the actual air-fuel ratio and the stoichiometric air-fuel ratio becomes large in the state where learning has progressed, proportional-integral control will be performed with a large control constant). The ability to follow the fuel ratio is improved.

In 818, the injection amount Ti is calculated according to the following equation.

TI=TpXCOEFxα×α0+Ts Here, in a steady state, the updated value of α0 is used, and in a transient state, the retrieved value is used as is.

The injection amount Ti is calculated as described above, and a drive pulse signal corresponding to the injection amount Ti is given to the fuel injection valve 22 at a predetermined timing via the current waveform control circuit 21.

In this example, the amount of deviation between the total fuel consumption and the stoichiometric air-fuel ratio, that is, the amount of deviation between the actual value of the control variable and the target value, was indirectly determined from the value of the feedback correction coefficient α, but this amount of deviation was directly calculated. Of course, it is a good thing.

Further, the present invention is not limited to such air-fuel ratio control, but can be applied to other electronic feedback control devices mounted on other vehicles, such as idle speed control.

<Effects of the Invention> As explained above, according to the present invention, an electronic system mounted on a vehicle determines a shift feedback correction amount by proportional-integral control and decreases a proportional constant and an integral constant according to the progress of the control. In the feedback control device, when the deviation between the actual value and the target value of the controlled variable exceeds a predetermined value, the proportionality constant and the integral constant are reset to predetermined initial values, so when the system suddenly changes, a large proportional The constant and the integral constant improve the ability of the quantity control amount to follow the target value, and after the control has progressed, stable control is achieved by the small proportional constant and integral constant.

[Brief explanation of drawings]

Fig. 1 is a 70-chart showing a conventional example, Fig. 2 is a block diagram showing the configuration of the present invention, Fig. 3 is a hardware configuration diagram of an embodiment of the present invention, and Fig. 4 shows the operation process of the same. FIG. 1...CPU 8...02 sensor

Claims (1)

[Claims] A means for determining a feedback correction amount for making a controlled variable follow a target value by proportional-integral control, and a means for decreasing the values of a proportional constant and an integral constant in the means in accordance with the progress of control. In a vehicle-mounted electronic feedback control device, means for detecting the amount of deviation between the target value and the actual value of the control amount, and detecting the proportionality constant and the integral when the amount of deviation detected by the means exceeds a predetermined value. An electronic feedback control variable ff for use in a vehicle, characterized in that a means for resetting a value of a constant to a predetermined initial value is provided.