JPH0697408B2 - Electronic feedback control system for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle-mounted electronic feedback control device for determining a feedback control correction amount by a proportional-integral method, and more particularly to a proportional constant and an integral constant depending on the progress of learning. The present invention relates to one having a function of changing.

<Background Art> As this kind of feedback control device, for example, one used for feedback control of feedback control of an air-fuel ratio as a controlled variable of an electronically controlled fuel injection internal combustion engine to a target value (for example, theoretical air-fuel ratio). There is.

To explain this, in the electronically controlled fuel injection 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 = Tp × COEF × α × Ts where Tp is the basic injection amount and is expressed as Tp = K × E / N, where K
Is a constant, Q is an intake air flow rate, and N is an engine rotation speed. COEF is a correction coefficient determined by various operating states, and α is a feedback back correction coefficient as a feedback correction amount for air-fuel ratio feedback back control (hereinafter referred to as λ control) described later. And Ts is the voltage correction,
This is for correcting variations in battery voltage. still,
Tp × COEF corresponds to the basic operation amount.

The λ control is equipped with an O ₂ sensor in the exhaust system to detect the actual air-fuel ratio, determine whether the air-fuel ratio is richer or thinner than the stoichiometric air-fuel ratio by the slice level, and the mixture supplied to the cylinder is stoichiometric air-fuel ratio. The fuel injection amount is controlled so that the air-fuel ratio is controlled so that the air-fuel ratio feed back correction coefficient α is set and the theoretical air-fuel ratio is maintained by changing this α. Is.

Here, the value of the air-fuel ratio feedback correction coefficient α is changed by a proportional-integral method (method using a proportional constant P and an integral constant I) for stable control.

That is, the output of the O ₂ sensor is compared with the slice level, and when the output of the O ₂ sensor is larger (smaller) than the slice level and the air-fuel ratio is thick (thin), the air-fuel ratio is suddenly made thin (dark). Instead, first decrease (increase) the proportional amount (hereinafter referred to as P minute), and then decrease (increase) by the integral amount (hereinafter referred to as I minute) to make the air-fuel ratio thin (dark). To control.

However, in a region where λ control is not performed, α = 1 is clamped and various correction coefficients COEF are set to obtain a desired air-fuel ratio.

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 set to the theoretical air-fuel ratio (λ =
If it can be set to 1), feed back control is not necessary, but in reality, variations in component parts (eg, air flow meter, fuel injection valve, pressure regulator, control unit) and changes over time, and fuel injection valve Since the deviation of the base air-fuel ratio from λ = 1 occurs due to factors such as non-linearity of pulse width vs. flow rate characteristics, changes in operating conditions and environment, etc., the value of α is changed by the proportional integration method as described above. The feedback control is performed so that = 1.

However, the deviation of the base air-fuel ratio from λ = 1 is different for each operating region, in other words, the value of α for obtaining λ = 1 is different for each operating region. Therefore, when this difference is large, the operating region is When it changes, the air-fuel ratio is changed to λ by the feedback control.
It takes time to settle to = 1.

As a result, the operation is performed at an air-fuel ratio with a poor conversion efficiency of the three-way catalyst, and in addition to cost increase due to an increase in the amount of precious metal in the catalyst, catalyst replacement is unavoidable due to the deterioration of conversion efficiency due to catalyst deterioration. The problem arises.

Therefore, the learning correction coefficient α as the learning correction amount is set so that the air-fuel ratio when α = 1, that is, the base air-fuel ratio is set to λ = 1.
₀ is introduced, and this α ₀ is learned and corrected so that λ = 1 when α = 1 in each operating state. As a result, the step of the base air-fuel ratio due to the change in the operating state is reduced, the period during which the air-fuel ratio deviates from λ = 1 is shortened, and P / in the proportional-integral method for determining the value of α is determined. I
A base air-fuel ratio learning control device has been conceived which enables the controllability to be improved by making the value of the minute smaller, thereby reducing the cost of the catalyst.

That is, for example, a map of the learning correction coefficient α ₀ having a value such that the base air-fuel ratio corresponding to engine operating conditions such as engine speed and load is λ = 1 is provided on the data storage means such as RAM of the microcomputer. , When the injection amount Ti is calculated, the basic operation amount Tp × COEF is corrected by the following formula.

Ti = Tp × COEF × α × α ₀ + Ts Here, learning of α ₀ proceeds in the following procedure.

i) In the steady state, the engine operating condition at that time and α
Detect and.

ii) Search for α ₀ that has been learned and stored so far in correspondence with the engine operating conditions.

iii) The value of α ₀ + Δα / M is obtained from this α and α ₀ , and the result is updated as a new α ₀ and the memory is updated.

Note that Δα indicates the amount of deviation from the reference value α ₁ , and Δα = α
−α ₁ , and the reference value α ₁ is generally 1.0. Further, M is a constant.

By the way, in adopting such a learning control device,
If P / I for determining the value of α is reduced from the beginning,
While learning is not progressing, that is, the base air-fuel ratio is λ
While not reaching = 1, the transient response is deteriorated. Conversely, learning progresses and the base air-fuel ratio is λ = 1.
If the λ control is performed with a large P / I amount while it is, the air-fuel ratio is fluctuated near λ = 1, which causes fluctuations in rotation speed and the like.

An invention for avoiding these problems has been made by the present applicant (Japanese Patent Application No. 58-076224), and this will be explained with reference to the first flow chart. That is, the learning control is performed in S101, the learning correction coefficient α ₀ updated in S102 is stored in the RAM, and the update count (learning count) C of α ₀ is counted up in S103. Then, at the next operation of this program, in S104 of the learning control routine of S101, it is determined whether or not the number of times C of updating α ₀ reaches a predetermined value, and if it is equal to or more than the predetermined value, learning progresses. If it is determined that the air-fuel ratio λ is close to 1, the process proceeds to S105 and the value of P / I of the PI method for determining α is decreased. on the other hand,
If the number of updates C of α ₀ is less than a predetermined value, it is determined that learning has not progressed, and the P / I-reduction process S105 is bypassed. That is, the value of P / I as well as the learning correction coefficient α ₀ is corrected according to the progress of learning.

In this way, the value of P / I in the PI method of the air-fuel ratio feedback back correction coefficient α is reduced according to the degree of progress of learning to improve the controllability, but the system changes suddenly (for example, when the vehicle is When entering a mountainous area and the temperature, atmospheric pressure, etc. decrease sharply, the learning correction coefficient α ₀ needs to be corrected (learning) accordingly, but it takes some time to do so. . Therefore, during this period, α is largely changed from 1 to maintain the air-fuel ratio at λ = 1.
When the learning progresses and the value of P / I for α determination is set to be small, it takes time to reach such an α value, and the followability to sudden changes in the system decreases. It was inconvenient.

This is not limited to the air-fuel ratio control as described above, the feedback control correction amount is determined by the proportional-integral method, and the electronic feedback control device mounted on the vehicle that reduces the proportionality and the integration constant according to the progress of learning is controlled. This is an inconvenience that generally occurs when the amount of deviation between the amount and the target value increases rapidly.

<Objects of the Invention> The present invention has been made by paying attention to such a conventional problem, and is stable and good in followability in an electronic feedback control device mounted on a vehicle for determining a feedback feedback correction amount by a proportional-integral method. An object of the present invention is to provide a control device that determines a proportional constant and an integral constant in the proportional-integral method so that various feedback control can be performed.

<Summary of the Invention> Therefore, in the present invention, as shown in FIG. 2, an electronic feedback control device for a vehicle, which feedback-controls a control amount to a target value, and a basic operation amount setting means for setting a basic operation amount. A feedback correction amount calculation means for calculating a feedback correction amount for correcting the basic operation amount according to the deviation between the actual value and the target value of the control amount by a proportional-integral method, and in correspondence with the operating conditions of the engine. Based on the stored learning correction amount and the deviation amount of the feedback correction amount and a predetermined reference value, a new learning correction amount for correcting the basic operation amount so that the control amount approaches the target value is set.
A learning unit for updating is provided, and while feedback control is performed based on the corrected basic operation amount, a unit for determining the degree of progress of learning according to the number of updates by the learning unit and a unit for determining by the determination unit. Means for decreasing and correcting the proportional constant and the integral constant of the feedback correction amount calculation means with an increase in the progress of learning, and when the deviation amount between the feedback correction amount and the reference value is equal to or more than a predetermined value, Means for resetting the number of updates and the proportional / integral constants to their respective initial values.

<Example> The present invention will be described below based on an example shown in FIG. 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.

Structure In the figure, 1 is a CPU, 2 is a P-ROM, 3 is a learning control CMOS-RAM, and 4 is an address decoder.
A back-up power supply circuit is used for RAM3 to retain the stored contents even after the key switch is turned off.

As the analog input signal to the CPU 1 for controlling the fuel injection amount, the intake air flow rate signal from the hot wire air flow meter 5, the slot opening signal from the slot sensor 6, the water temperature signal from the water temperature sensor 7, the O ₂ sensor There is an oxygen concentration signal in exhaust gas from 8 and a battery voltage from battery 9, which are inputted via the analog input interface 10 and the A / D converter 11. 12 A / D conversion timing controller. Digital input signals include ON / OFF signals from the idle switch 13, the start switch 14 and the neutral switch 15, and these are inputted via the digital input interface 16.

In addition, for example, a reference signal at every 180 ° and a position signal at every 1 ° from each crank sensor 17 are input through the one-shot multi-circuit 18. In addition, the vehicle speed signal from the vehicle speed sensor 19 is a waveform shaping circuit.
It is supposed to be entered through 20.

Output signal from CPU1 (drive pulse signal to fuel injection valve)
Are sent to the fuel injection valve 22 via the current waveform control circuit 21.

Action Next, the action of this product will be described with reference to the flow chart shown in FIG.

At S1, the intake air flow rate Q obtained from the signal from the air flow meter 5 and the engine speed N obtained from the signal from the crank angle sensor 17 are used to determine the basic injection amount Tp (= K
× Q / N) is calculated.

In S2, set the correction coefficient COEF determined from various operating conditions.

In S3, it is determined whether or not the number of updates C of the learning correction coefficient α ₀ (counted up in S16, which will be described later) has reached a predetermined value, and if it is greater than or equal to the predetermined value, the degree of progress of learning control increases. It is determined that the operation is being performed, the count value C is cleared in S4, the P / I amount for determining α is decreased by a predetermined amount in S5, and then the process proceeds to S6. On the other hand, when it is less than the predetermined value, it is determined that the signal level of the learning control has not increased, and the process directly proceeds to S6 without changing the P / I amount. That is, step S3 corresponds to the learning progress degree determining means shown in FIG. 2, and step S5 corresponds to the proportional-integral-constant decrease correcting means. As a result, stable control in which fluctuations in the rotational speed are suppressed by a small control constant is performed, and at the same time, the fluctuation range of the air-fuel ratio is reduced, so that the conversion rate of the exhaust purification catalyst is improved.

In S6, the output from the O ₂ sensor 8 is compared with the slice level, and the air-fuel ratio feedback correction coefficient α is calculated by the proportional integration method based on the P / I portion. This step S6 corresponds to the feed back correction amount calculation means in FIG.

In S7, the voltage correction component Ts is set based on the battery voltage from battery 9.

In S8, the learning correction coefficient α ₀ is retrieved from the engine speed N and the basic injection amount (load) Tp. The map of the learning correction coefficient α _{0 with} respect to the rotational speed N and the basic injection amount Tp is stored in the rewritable RAM 3, and α ₀ = 1 is set when learning is not started. Further, this map has N = 8 lattices and Tp = 4 lattices.

S9 to S12 are provided to detect the steady state.
In 9 the change of the vehicle speed is judged based on the signal from the vehicle speed sensor 19, in S10 the gear position is judged based on the signal from the neutral switch 15, and in S11 the throttle opening is started based on the signal from the throttle sensor 6. Judge the change of the degree, S12
At, it is determined whether or not a predetermined time has elapsed, and if it is within the predetermined time, the process returns to S9. Thus, if the change in vehicle speed is less than or equal to a predetermined value within a predetermined time, and the gear is engaged, and if the change in the throttle opening is less than or equal to a predetermined value, it is determined that the steady state is reached, and in S13 and S14. The learning correction coefficient α ₀ is corrected.

The correction of the learning correction coefficient α ₀ in S13 when it is determined to be in the steady state is α ₀ ← α ₀ + as in the conventional case described above.
It is done based on the formula Δα / M. As mentioned above,
Where Δα is the feedback correction coefficient α and the reference value α
The deviation amount from ₁ is Δα (= α−α ₁ ), and the value when feedback correction is not performed, for example, α ₁ = 1 is selected as the reference value α ₁ .

In S14, a new learning correction coefficient α ₀ is written in the RAM 3 at the corresponding engine rotation speed N and basic injection amount Tp. That is, the data in RAM3 is updated.

In S15, the deviation amount Δα is compared with a predetermined value, and if Δα is smaller than the predetermined value, learning is in progress (the air-fuel ratio is the theoretical air-fuel ratio λ
Is approaching = 1), the process proceeds to S16, and the value of the update count C of α ₀ is incremented by 1.

On the other hand, if Δα is larger than the predetermined value, it is determined that the difference between the air-fuel ratio and the logical air-fuel ratio is large, and the value of the update count C is reset to zero in S17, and the proportional constant and integral constant of the PI method are set. Is reset to an initial value that has a predetermined, sufficiently large value. That is, this step 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 logical air-fuel ratio becomes large in the state where learning has advanced, the proportional-integral method will be made with a large control constant, and the air-fuel ratio will follow the theoretical air-fuel ratio. Will be good.

In S18, the injection amount Ti is calculated according to the following equation.

Ti = Tp × COEF × α × α ₀ + Ts Here, the updated one is used as α ₀ in the steady state, and the retrieved one is used as it is in the transient state.

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

In the present embodiment, the deviation amount between the air-fuel ratio and the logical air-fuel ratio, that is, the deviation amount between the actual value and the target value of the control amount is indirectly obtained from the value of the feed back correction coefficient α. Needless to say, it is even better.

Further, the present invention is not limited to such air-fuel ratio control, but can be applied to an electronic feedback control device mounted on another vehicle, such as an idle speed control.

<Advantages of the Invention> As described above, according to the present invention, the feedback correction amount is calculated by the proportional-plus-integral method, and the proportional constant and the integral constant are decreased in accordance with the progress of the learning control. As the control progresses, it is possible to reduce the fluctuation amount of the control value in the steady state, stable control is performed, and at the same time, for example, in the case of application to air-fuel ratio feedback control of an internal combustion engine, suppression of rotation speed fluctuation and The conversion rate of the exhaust purification catalyst can be improved. Further, since the proportional / integral constant is reset to the initial value when the feedback correction amount and the deviation amount of the reference value exceed a predetermined value, a large proportional / integral constant is used as a target of the control amount when the system suddenly changes. The ability to follow the value is improved.

[Brief description of drawings]

FIG. 1 is a flow chart showing a conventional example, FIG. 2 is a block diagram showing a constitution of the present invention, FIG. 3 is a hardware constitutional diagram of an embodiment of the present invention, and FIG. 4 shows an operating process of the same. It is a flow chart. 1 ... CPU, 8 ... O ₂ sensor

Claims (1)

[Claims] 1. An electronic feedback control device for a vehicle, which feedback-controls a controlled variable to a target value, wherein a basic manipulated variable setting means for setting a basic manipulated variable and a deviation between an actual value and a target value of the controlled variable. A feedback correction amount calculation means for calculating a feedback correction amount for correcting the basic operation amount according to the proportional integration method; and a learning correction amount stored in association with the operating condition of the engine,
A learning unit that sets and updates a new learning correction amount that corrects the basic operation amount so that the control amount approaches the target value, based on the feedback correction amount and the deviation amount of a predetermined reference value, While performing feedback control based on the corrected basic operation amount, a means for determining the degree of progress of learning according to the number of updates by the learning means, and an increase in the degree of progress of learning determined by the determination means Means for decreasing and correcting the proportional constant and the integral constant of the feedback correction amount calculation means, and the number of updates and the proportional / integral constant respectively when the deviation amount between the feedback correction amount and the reference value exceeds a predetermined value. An electronic feedback control device mounted on a vehicle, comprising: means for resetting to an initial value.