JPH1162675A - Positioning control device for throttle valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a throttle valve from minute vibration caused by discordance of the resolution between the throttle valve opening command value and the measured value of opening. SOLUTION: The resolution of the throttle valve opening command value is changed in compliance with the resolution of the measured value of the degree of throttle valve opening. This prevents the throttle valve from minute vibration caused by discordance of the resolution between the throttle valve opening command value and the measured value of opening, eliminates pulsation in the intake air to lead to enhancement of the controlling performance of engine, and also permits enhancement of the durability of a throttle valve opening sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a throttle valve positioning control device for controlling an intake air amount of an internal combustion engine.

[0002]

2. Description of the Related Art A disturbance applied to an actuator is estimated based on an actuator operation amount and a measured value of a throttle valve opening, and the actuator operation amount is corrected by the disturbance to improve the dynamic characteristics of the actuator. A throttle valve positioning control device has been proposed (for example, see Japanese Patent Application No. 7-320476). In this control device, an analog signal detected by a throttle valve opening sensor is converted into a digital signal and used as a measured value of the throttle valve opening.

[0003] When an analog signal of the opening sensor is converted into a digital signal, the resolution of the measured opening value is determined by the accuracy of the A / D converter. On the other hand, in the digital calculation by the microcomputer, it is possible to perform the calculation with a resolution higher than the resolution of the opening measurement value,
The throttle valve opening command value may be given with a higher resolution than the resolution of the opening measurement value.

However, if the positioning control of the throttle valve is performed in a state where the resolution of the opening command value does not match the resolution of the measured opening value, the measured value of the throttle valve opening will be made closer to the throttle valve opening command value. Since the disturbance compensator operates, the throttle valve slightly vibrates between the measurement value resolutions. Such a minute vibration may cause pulsation of the intake air to deteriorate the control performance of the engine, and may also reduce the durability of the throttle valve opening sensor, particularly the contact type detection sensor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a throttle valve positioning control device which prevents a minute vibration of the throttle valve due to a mismatch between the resolution of the throttle valve opening command value and the measured value of the opening.

[0006]

[Means for Solving the Problems]

(1) An actuator for opening and closing a throttle valve of an internal combustion engine, a driving unit for driving the actuator according to a drive command value, a measuring unit for measuring an opening of the throttle valve, and a throttle valve opening Control means for calculating a drive command value for matching the responsiveness of the actual throttle valve opening to the command value to a preset response characteristic; an actuator and a drive means based on the drive command value and the measured throttle valve opening value And a disturbance estimating means for estimating a disturbance applied to the measuring means, and a correcting means for correcting a drive command value based on the disturbance estimated value, the throttle valve positioning control device comprising: There is provided a command value resolution changing means for changing the value in accordance with the resolution of the valve opening measurement value. (2) The throttle valve positioning control device according to claim 2, further comprising a measurement value resolution changing means for changing the measurement value resolution in accordance with the throttle valve opening measurement value, and the command value resolution changing means, the measurement value resolution changing means. The resolution of the throttle valve opening command value is changed according to the measured value resolution changed by the above.

[0007]

【The invention's effect】

(1) According to the first aspect of the invention, it is possible to prevent the minute vibration of the throttle valve due to the resolution mismatch between the throttle valve opening command value and the measured opening value, and to eliminate the pulsation of the intake air, thereby improving the control performance of the engine. At the same time, the durability of the throttle valve opening sensor is improved. (2) According to the second aspect of the invention, even if the measured value resolution is changed according to the measured value of the throttle valve opening in order to improve the positioning control accuracy of the throttle valve, the measured value resolution is changed according to the changed measured value resolution. Thus, the command value resolution is changed, so that the positioning control accuracy is improved over the entire throttle valve opening in addition to the effect of the first aspect.

[0008]

FIG. 1 is a functional block diagram showing a configuration of an embodiment. Throttle actuator 1
Drives a butterfly type throttle valve provided in an intake air passage of an internal combustion engine. A DC motor is used as a drive source, and the output of the motor is reduced by a speed reducer to open / close a throttle valve biased by a spring. The sensor 2 detects the opening of the throttle valve. In this embodiment, an inexpensive potentiometer that outputs an analog signal is used, but a high-precision optical encoder may be used. The sensor signal processing circuit 3 has an amplifier and an A / D converter, amplifies an analog signal from the opening sensor 2 and converts it into a digital signal. The throttle valve positioning controller 4 is composed of a microcomputer and its peripheral parts, and calculates a motor current command value such that the throttle valve opening measurement value follows the opening command value. The current control amplifier 5 controls the switching time of the power transistor so that the actual motor current follows the motor current command value.

In this embodiment, a feedback type current control amplifier using a current detection sensor is used, but the current control amplifier is not limited to this embodiment.
For example, based on the throttle valve opening and the output of a model matching compensator described later, the back electromotive force of the motor is estimated using a dynamic characteristic model of the control object that is stabilized by a disturbance compensator described later. A feed-forward type current control amplifier may be used that corrects the effective voltage obtained from the current command value with the value to calculate and control the switching time of the current control power transistor.

FIG. 2 is a control block diagram showing the configuration of the throttle valve positioning controller 4. The throttle valve positioning controller 4 is provided with a disturbance compensator 11 to obtain a low sensitivity characteristic with respect to disturbance and parameter fluctuation.
15 and a model matching compensator 16 to 19 for matching the responsiveness of the actual throttle valve opening to the throttle valve opening command value to a predetermined desired response characteristic.
And The current control amplifier 5, the throttle actuator 1 including a motor and a valve movable mechanism, the opening sensor 2 and the sensor signal processing circuit 3 are controlled by the controller 4, and the throttle valve opening command value θr is controlled by the throttle valve. The valve opening command value (target value) and the current command value Ir are the above-described drive command value (operation amount), and the throttle valve opening θ is the above-described throttle valve opening measurement value (control amount).

First, the disturbance compensators 11 to 15 will be described. The continuous system transfer characteristic Gp (s) of the controlled object from the current command value Ir to the throttle valve opening θ is represented by (K / (as
² + bs + c)) (hereinafter referred to as 0 order / 2 order)
The transfer characteristic obtained by discretizing this is represented by Gp (z ^-1 ).

(Equation 1)

The zero point (-bp0 / bp) of Gp (z ^-1 )
Since 1) converges to −1 as the sampling time becomes shorter, it becomes unstable when the inverse system of Gp (z ⁻¹ ) is used for the compensator. To avoid this, a disturbance compensator is designed as follows. The control block 11 adds Gp to the low-pass filter H0 (z ⁻¹ ) having a steady-state gain of 1.
(Z ^-1) is the filter H obtained by adding the Q (z ^-1) having a zero point (z ^-1). The control block 11 performs a low-pass filter process on the current command value Ir to perform the current command value Ir ′
Is output.

(Equation 2)

The control block 12 includes a filter H (z ^-1 ) /
Gp (z ^-1 ). Therefore, the zero points converging to -1 are canceled, and the control block 12 becomes a stable digital filter. The control block 12 controls the current command value I
The current command value is back calculated based on the discrete system transfer characteristic Gp (z ^-1 ) of the controlled object from r to the throttle valve opening θ and the throttle valve opening θ, and further processed by a low-pass filter to obtain the current command value Ir. Is output. The subtractor 14 outputs
The current command value Ir ′ is subtracted from the current command value Ir ″, and the deviation u2 of the current command value Ir due to a disturbance of the control target from the current amplifier 5 to the sensor signal processing circuit 3 or a parameter variation (hereinafter referred to as a disturbance estimated value and Further, the subtractor 15 subtracts the disturbance estimation value u2 from the current command value u1 and corrects it, and outputs a current command value Ir excluding the influence of disturbance and parameter fluctuation.

The disturbance estimation value u2 becomes zero when there is no disturbance or parameter fluctuation in the control target. Disturbance d
Or parameter variation Δ,

(Equation 3) In the frequency band where the gain characteristic of H (z ^-1 ) is 1,

４ = Gp (z ⁻¹ ) · u1 That is, the influence of the disturbance and the parameter fluctuation is completely canceled, and the dynamic characteristics of the control target are fixed to the nominal model Gp (z ^-1 ). When the cutoff frequency of H (z ^-1 ) is increased, the same effect can be obtained up to a high frequency range. However, a high gain feedback is obtained, and the stability margin is reduced. Therefore, a trade-off design is required. The control block 13 is a limiter corresponding to the upper and lower limits of the motor current. By limiting the input of the disturbance compensator when the motor current, which is the input of the actual control target, is saturated, an error is accumulated in the estimated disturbance value u2. To prevent the response performance from deteriorating.

Next, the model matching compensators 16 to 19
Will be described. First, a desired response characteristic is given as a continuous system reference model transfer characteristic Gm0 (s) (0th order / 2nd order).
If this is the discretized reference model transfer characteristic Gm0 (z ^-1), in the same manner as the control target of the transfer characteristic Gp (z ^-1), with a zero point to converge to -1 The smaller the sampling time. Therefore, the reference model transfer characteristic G is used for the purpose of canceling both when designing the model matching compensator.
The zero point of m0 (z ^-1 ) is set to the control target transfer characteristic Gp (z ^-1 ).
Gm (z ^-1 ) replaced with the zero point of is used as the reference model transfer characteristic. If the sampling time is sufficiently short, there is almost no difference between Gm (z ^-1 ) and Gm0 (z ^-1 ), and there is no practical problem.

(Equation 5)

Using the coefficients of Equations 1 and 5, the control block 16 of the model matching compensator uses 1 / R
(Z ^-1 ), the control block 17 is composed of L (z ^-1 ), and the control block 18 is composed of Bmf.

(Equation 6)

FIG. 3 is a flow chart showing the throttle valve positioning control. The throttle valve positioning controller 4 executes this control program every 2 ms. In step 1, the analog output signal of the throttle valve opening sensor 2 is amplified and converted into a digital signal. In step 2, the signal is converted into a throttle valve opening θ. In step 3, the throttle valve opening with different precision is switched. In step 4, the opening degree command value θr of the actuator
To determine. In step 5, from the opening command value θr, A /
The resolution of the opening command value θr is made to match the resolution of the opening measurement value θ by discarding bits smaller than the least significant bit of the D-converted opening measurement value θ. In the following step 6, the frequency characteristics of the robust compensators of the control blocks 11 and 12 in FIG. 2 are switched according to the control state of the engine. In step 7, the disturbance estimation value u2 calculated by the disturbance compensators 11 to 14 is subtracted from the current command value u1 calculated by the model matching compensators 16 to 19 in FIG. The excluded current command value Ir is obtained. In the following step 8, the current command value Ir is output to the current control amplifier 5 to drive the DC motor.

-Modification of One Embodiment of the Invention-When the resolution of the measured opening value is changed according to the control state of the engine such as the throttle valve opening, the resolution of the opening command value is also changed. A modification of the above-described embodiment, which is changed in accordance with the degree measurement value resolution, will be described.

FIG. 4 is a flowchart showing a throttle valve positioning control according to a modification. Steps that perform the same processing as the processing shown in FIG. 3 are assigned the same step numbers, and differences will be mainly described. In step 3A, switching of the throttle valve opening with different precision is performed. When the analog output signal of the throttle valve opening sensor 2 is amplified and A / D-converted and used as a measured throttle valve opening value in the calculation of the disturbance compensators 11 to 15 and the model matching compensators 16 to 19, the sensor 2 Since a certain amount of noise is always mixed in the analog output signal, the disturbance compensators 11 to 15 may not function sufficiently and may not achieve the target throttle control resolution.

Therefore, as shown in FIG. 5, the analog output signal of the throttle valve opening sensor 2 is greatly amplified (four times in this example) to relatively reduce high frequency noise exceeding the effective frequency of the amplifier. I do. Also,
Since the input voltage of the A / D converter naturally has an upper limit, this operation is performed only at the time of idle control where a very high throttle control resolution is required, that is, only in a low throttle valve opening range. As shown in (2), an ordinary A / D conversion value that is not amplified is interpolated and used as a throttle valve opening measurement value. In order to smoothly connect both A / D conversion values, an interpolation operation is performed between the two based on a normal A / D conversion value that is not amplified or a value obtained by performing an interpolation operation one sample cycle earlier.

[Mathematical formula-see original document] Interpolation value = k * (A / D conversion value 2) + (1-k)
(A / D conversion value 1) Here, when (A / D conversion value 1) ≦ θ, k = 1, θ2
0 <k <1, θ2 when <(A / D conversion value 1) <θ1
If ≤ (A / D conversion value 1), k = 0.

In step 5A, in step 3A
When the resolution of the opening measurement value is changed in accordance with the opening measurement value, the opening command value resolution is changed in accordance with the changed opening measurement value resolution.

FIG. 7 is a diagram showing a simulation result of the conventional control device, and FIG. 8 is a diagram showing a simulation result according to the embodiment of the present invention. Note that the resolution of the opening measurement value was 0.025 degrees, and the resolution of the opening command value was 1.0125 degrees higher than the opening measurement value. 7 and 8, the horizontal axis is time t, the vertical axis is the throttle valve opening (degree), θr is the opening command value, θ is the opening measurement value, θr1 is the opening command value before changing the resolution, θr2. Is the opening command value after changing the resolution. According to the conventional control device, when the opening command value resolution has a higher resolution than the opening measurement value resolution, as shown in FIG. 7, intense minute vibration occurs between the resolutions. On the other hand, according to the embodiment of the present invention, by matching the resolution of the opening command value and the resolution of the measured opening value, it is possible to prevent minute vibrations occurring below the resolution as shown in FIG. As a result, the pulsation of the intake air is eliminated, the control performance of the engine is improved, and the durability of the throttle valve opening sensor is improved.

In the above embodiment, the throttle actuator 1 controls the actuator, the current control amplifier 5 controls the driving means, and the throttle valve opening sensor 2
Are the measuring means, the model matching compensators 16 to 19 are the control means, the disturbance compensators 11 to 15 are the disturbance estimating means and the correcting means, and the throttle valve positioning controller 4 is the command value resolution changing means and the measurement value resolution changing means. Configure each.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a control block diagram showing a configuration of a throttle valve positioning controller.

FIG. 3 is a flowchart showing positioning control of a throttle valve according to one embodiment.

FIG. 4 is a flowchart showing a throttle valve positioning control according to a modification of the embodiment.

FIG. 5 is a diagram for explaining a method of switching an opening measurement value resolution in accordance with a throttle valve opening.

FIG. 6 is a diagram for explaining a method of switching the resolution of an opening measurement value in accordance with a throttle valve opening.

FIG. 7 is a diagram showing a simulation result of a conventional throttle valve positioning control device.

FIG. 8 is a diagram showing a simulation result of one embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throttle actuator 2 Throttle valve opening sensor 3 Sensor signal processing circuit 4 Throttle valve positioning controller 5 Current control amplifier 11-15 Disturbance compensator 16-19 Model matching compensator

Claims (2)

[Claims] 1. An actuator for opening and closing a throttle valve of an internal combustion engine; a driving unit for driving the actuator according to a driving command value; a measuring unit for measuring an opening of the throttle valve; Control means for calculating the drive command value for causing the responsiveness of the actual throttle valve opening to match the response characteristic set in advance; and the actuator based on the drive command value and the throttle valve opening measurement value. A throttle valve positioning control device comprising: a disturbance estimating means for estimating a disturbance applied to a driving means and the measuring means; and a correcting means for correcting the driving command value based on the disturbance estimated value. Change the resolution of the command value according to the resolution of the throttle valve opening measurement value A throttle valve positioning control device comprising command value resolution changing means. 2. The throttle valve positioning control device according to claim 1, further comprising: a measurement value resolution changing unit that changes a measurement value resolution according to the throttle valve opening measurement value. A throttle valve positioning control device for changing the resolution of the throttle valve opening command value in accordance with the measured value resolution changed by the measured value resolution changing means.