JPH11353003A - Method and device for switching pid constant and fuel jet controller provided with the same device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the change of a proportional integral and derivative(PID) constant in simple configuration without making the operation of a control system unstable. SOLUTION: First and second MOS FETs 26 and 27 are connected in parallel to a first resistor 21 for a PID constant of a PID control circuit 8 and in a prescribed case, a pulse signal to gradually shorten its repetition cycle is outputted from a CPU 5. Then the first and second MOS FETs 26 and 27 are turned on/off through a first transistor 25 and finally turned into the ON state. Therefore, the first resistor 21 for the PID constant is equivalently and gradually made from a non-short-circuitting state to a short circuit state and the so-called PID constant is equivalently and continuously changed so that the unstable state of control operation is not brought.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called PID control circuit, and more particularly, to a so-called PID control circuit in which switching of a so-called PID constant is improved.

[0002]

2. Description of the Related Art PID (Proportional Integral)
A PID control circuit based on a control operation known / known as “derivative” control is used in various devices. For example, in a fuel injection control device for a vehicle using a diesel engine, a so-called electromagnetic actuator called an electronic governor is used as an actuator of a fuel injection pump to rotate a control shaft in the injection pump. I have. And this electronic governor
It is controlled by an analog feedback circuit, and PID control is used in the feedback control. PI in such a fuel injection control device
In the D control, a so-called PID constant has conventionally been usually used while being fixed.

[0003]

In recent years, as further improvement of vehicle performance has been desired, various studies have been made on the above-described fuel injection control device. To realize fine control, switching a so-called PID constant is one of the measures. However, switching the PID constant stepwise during the control operation makes the operation of the control system temporarily unstable. In particular, in the fuel injection control as described above, it is necessary to avoid stepwise switching of the PID constant from the viewpoint of ensuring smooth rotation of the engine, and a measure for smoothly switching the PID constant is desired. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a PID constant switching method, a PID constant switching apparatus, and a PID constant that enable a PID constant to be changed with a simple configuration without making the operation of a control system unstable. A fuel injection device having a switching device is provided. Another object of the present invention is to provide a PID capable of changing a PID constant with a simple configuration without impairing the smoothness of engine rotation.
It is an object of the present invention to provide a constant switching method, a PID constant switching device, and a fuel injection device having the PID constant switching device.

[0004]

According to a first aspect of the present invention, there is provided a method of switching a PID constant, wherein a switching element is connected in parallel to a desired one of a plurality of resistors connected in series as a PID constant of a PID control circuit. The PID constant is changed from a predetermined value to a predetermined value by changing the combined resistance value of the plurality of series-connected resistors equivalently and continuously by controlling connection and on / off control of the switching element. The switching is configured to be performed gradually equivalently.

According to such a method, the resistance value is gradually changed to a predetermined value equivalently, and the unstable operation state, which has conventionally occurred in the PID control circuit, is changed by instantaneously changing the resistance value. That we can avoid, especially
In order to gradually change the resistance value equivalently, so-called PWM control, in which the on / off time of the switching element connected in parallel to the resistor is gradually shortened and finally turned on, is performed. The switching of the PID constant from a predetermined value to a predetermined value is equivalently and gradually performed by applying to the switching element.

According to a third aspect of the present invention, there is provided a PID constant switching device for switching the PID constant of a PID control circuit having a plurality of resistors connected in series as one of the PID constants. And a constant switching means connected to a predetermined resistor among the plurality of resistors and gradually changing the resistor equivalently from a non-short-circuited state to a short-circuited state.

Such a configuration is particularly suitable for executing the above-described PID constant switching method according to the first aspect of the present invention. The constant switching means has a switching element connected in parallel to a predetermined resistor. The on / off state of the switching element is controlled by a signal input from the outside. It is preferable that the signal input from the switching element be such that the on / off interval of the switching element becomes shorter as time elapses, and finally turns on. That is, it is preferable that the constant switching means has a switching element, and the switching element is configured to be turned on / off by so-called PWM control.

According to a fifth aspect of the present invention, there is provided a fuel injection control device having a PID constant switching device, which controls the operation of a fuel injection pump having an electronic governor using an electric actuator. A control device, wherein the fuel injection control device includes a sensor for detecting an operation amount of the electric actuator, and an energization to be applied to the electric actuator to obtain a target operation amount of the electric actuator. A target value corresponding to the magnitude of the current, a comparator that compares the output signal of the sensor, and an energization control circuit that controls energization of the electric actuator at a repetition cycle corresponding to the output of the comparator. Have,
In the comparator, a PID control circuit is provided between an input terminal and an output terminal thereof to form a feedback loop. The PID control circuit includes a plurality of PID constants connected in series as one of PID constants. And a constant switching means connected to a predetermined resistor among the plurality of resistors, and equivalently gradually changing the resistor from a non-short-circuited state to a short-circuited state. A PID constant switching device is provided.

In this configuration, the PID constant switching device according to the third aspect of the present invention is provided in a fuel injection control device having a PID control circuit.
The ID constant can be gradually changed from a predetermined value to a predetermined value, whereby the PID constant can be changed with a simple configuration without impairing the smoothness of engine rotation. It becomes.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The members, arrangements, and the like described below do not limit the present invention, and can be variously modified within the scope of the present invention. First, the configuration of a fuel injection control device to which the present invention is applied will be described with reference to FIG. This fuel injection control device is configured, for example, to perform fuel injection of the diesel engine 1 by so-called analog feedback. The diesel engine 1 receives fuel injection from a fuel injection pump 2, and the fuel injection pump 2 has an electric actuator 3 for fuel injection control called a so-called electronic governor. By controlling the current supplied to the electromagnetic coil 3a of the electric actuator 3, the operation amount of the electric actuator 3 is controlled, and as a result, the fuel injection amount from the fuel injection pump 2 to the diesel engine 1 is adjusted. It is something that is to be done.

The operation of the electric actuator 3 is performed by a CPU.
The control is performed by adjusting the magnitude of the energizing current by so-called feedback control based on the target value from the sensor 5 and the detection signal from the sensor 4. In the feedback control, the so-called PID ( Proportiona
l Integral and Derivative) control is performed. That is, the sensor 4 provided in the fuel injection pump 2 detects, for example, the amount of rotation of a rotary shaft (not shown) of the electric actuator 3, and a detection signal from the sensor 4 is: The sensor circuit 6 performs noise removal and conversion to an appropriate signal level, and inputs the signal to an inverting input terminal of a comparator 7 including an operational amplifier 7a.

On the other hand, the CPU 5 is a so-called one-chip microcomputer having a built-in ROM, RAM, etc., which executes a fuel injection control program and sets a target current to be supplied to the electromagnetic coil 3a. the value, for example, and outputs from the analog output terminal P _1. C
The target value that determines the current flowing through the electromagnetic coil 3a output from the PU 5 is applied to the non-inverting input terminal of the operational amplifier 7a. The operational amplifier 7a is provided with a PID control circuit (denoted as "PID" in FIG. 1) 8 between the output terminal and the inverting input terminal.
The PID constant is configured to be added to so-called feedback control.

The result of comparison by the comparator 7 is input to an energization control circuit 9, which controls energization of the electromagnetic coil 3a in accordance with the comparison result. That is, the energization control circuit 9 is configured to receive a comparison result from the comparator 7 and output a repetitive pulse signal having a so-called duty ratio according to the comparison result (in FIG. 1, “PW
M ") and a drive transistor 10 which is turned on / off in response to an output pulse signal of the PWM circuit 10A.
B.

A power supply voltage (not shown) is applied to one end of the electromagnetic coil 3a, and the other end is connected to a drive transistor 10B. The drive transistor 10B repeats the output from the PWM circuit 10A. A so-called on / off operation is performed according to the pulse signal. The so-called duty ratio of the repetitive pulse signal output from the PWM circuit 10A is determined by the comparator 7
The duty ratio is changed to control the amount of current to the electromagnetic coil 3a as a result. I have. Further, the so-called PID constant of the PID control circuit 8 can be continuously switched to a desired constant by the CPU 5 through a constant switching circuit 11 as constant switching means in a predetermined case as described later. Is what it is.

Next, the CPU will be described with reference to FIGS.
5 and the switching of the PID constant by the constant switching circuit 11 will be described. First, a specific circuit configuration example will be described with reference to FIG. First, the PID control circuit 8
Are the first resistor 21 for the PID constant and the second resistor 21 for the PID constant.
Is connected in series, the first resistor 21 for the PID constant is on the inverting input terminal side, and the first capacitor 23 for the PID constant is on the output terminal side. Are provided in series between the inverting input terminal and the output terminal of the operational amplifier 7a.

The constant switching circuit 11 is mainly composed of a so-called switching circuit of the first and second MOS FET26,27 as a switching element driven in response to repetitive pulse signals output from a so-called port output P ₀ of the CPU5 Is constituted. That is, the constant switching circuit 11 first sets npn to the input stage.
A first transistor 25 is provided, the base of which is connected to the port output terminal P ₀ of the CPU 5 via a first resistor 31 and to ground via a second resistor 32. It is connected. Also, the first resistor 31
At the end of the side connected to the port output terminal P _0, one end of the third resistor 33 is connected. And this third
The other end of the resistor 33, being adapted to supply voltage Vcc is applied, the port output P ₀ of the CPU5 the voltage Vcc, are to be called pulled up.

The emitter of the first transistor 25 is connected to ground, while the collector is connected to a fourth resistor 34.
With the predetermined voltage V _B (V _B <Vcc) is adapted to be applied through, and is connected to the gates of the first and second MOS FET26,27 via the fifth resistor 35 . In this circuit configuration example, the first of the N channels
And the second MOS FETs 26 and 27 are used. The sources are connected to each other, while the first MOS FE
The drain of T26 is connected to the connection point of the first and second PID constant resistors 21 and 22, and the drain of the second MOS FET 27 is connected to the first resistor 21 for PID constant and the inverting input terminal of the operational amplifier 7a. Are connected respectively to the connection points with. In other words, the first connected in series
And the second MOS FETs 26 and 27 are connected in parallel to the first resistor 21 for the PID constant. Then, the first and second MOS FETs 2
When the first transistor 25 is turned off, the transistors 6 and 27 are turned on (on).
The first resistor 21 for ID constant is in a short-circuit state.

The operation of the above configuration will be described. First, the CPU 5 executes, for example, a program for controlling the operation of the fuel injection control device.
PID constant switching is executed as a so-called subroutine process. That is, FIG. 3 is a flowchart showing the procedure of the PID constant switching control as the subroutine processing. Referring to FIG. 3, when this subroutine processing is started, first, the PID The CPU 5 determines whether it is necessary to switch the constant based on a predetermined reference (see step 100 in FIG. 3). If it is determined that there is no need to switch the PID constant (NO), this subroutine processing ends, and the process returns to the main routine (not shown). When the PID constant is not switched, the port output terminal P ₀ of the CPU 5 is kept at a voltage level (substantially ground potential) corresponding to a so-called logical value High. Therefore, the first transistor 25 is turned on and the first and second MOS FETs 2
6, 27 are rendered non-conductive. Therefore, the first resistor 21 for the PID constant is in a non-short-circuit state, and the PID control circuit 8 sets the first and second resistors 21
22 and the first capacitor 23 for the PID constant.

Meanwhile, if it is determined that there is the need for switching of the PID constants (in the case of YES), the pulse signal as described next from a port output terminal P ₀ of the CPU5 is output (Fig. 3 Step 102). That is, from the port output terminal P ₀ of the CPU 5, a repetitive pulse signal whose pulse interval gradually decreases with time, in other words, PWM (Pulse Width)
Modulation) pulse signal is output.
Port output P ₀ of 5, and thus is held at a predetermined voltage level corresponding to a so-called logic value Low (FIG. 4
(A)). Here, the interval 1 / f of the first pulse signal
It is desirable that s (see FIG. 4A) be a value sufficiently smaller than the frequency response speed of the electric actuator 3. This means that the interval of the first pulse signal is 1 / fs.
However, if the frequency response speed of the electric actuator 3 is not sufficiently small, the operation of the electric actuator 3 will fluctuate, and the operation of the fuel injection control device will fluctuate.
This is because the meaning of performing the constant switching control is lost.

Then, the port output terminal P ₀ has a logical value Lo.
During a predetermined voltage level corresponding to w, the first and second MOS FETs 26 and 27 are in a conductive state.
In the ID control circuit 8, the first resistor 21 for the PID constant is short-circuited, and the second resistor 22 for the PID constant is connected between the inverting input terminal and the output terminal of the operational amplifier 7a.
And the PID constant first capacitor 23 are connected in series. On the other hand, the port output terminal P ₀ has the logical value Hi.
When the voltage returns to the predetermined voltage level corresponding to gh, the first and second MOS FETs 26 and 27 return to the non-conductive state, and the first resistor 21 for the PID constant returns to the non-short-circuit state. Therefore, the process of step 102 is started, and a pulse signal is repeatedly output from the port output terminal P ₀ , and finally, the port output terminal P ₀ has the logical value Lo.
The change in the resistance of the PID control circuit 8 until the state is maintained at the predetermined voltage level corresponding to w, that is, the inverting input terminal of the operational amplifier 7a and the second resistor 22 for the PID constant The substantial change in the combined resistance value between the PID constant and the connection point with the first capacitor 23 is as follows.
As shown in FIG. 4B, first, the resistance value (R ₁ + R ₂ )
Those were found over time is output repeatedly pulse signal Yuku elapsed, Yuki decreases towards gradually to the resistance value R _2, in the end, becomes to be a resistance value R _2. Here, R ₁ is the resistance value of the first resistor 21 for the PID constant, and R ₂ is the second resistor 2 for the PID constant.
2 represent the respective resistance values.

As described above, the so-called PID constant of the PID control circuit 8, particularly the resistance value as the proportional constant, is gradually and continuously changed from (R ₁ + R ₂ ) to R ₂ by the processing of step 102. Therefore, the operation of the electric actuator 3 does not fluctuate at all. As a result, the switching of the proportional constant in the PID control circuit 8 is equivalently and gradually performed without any change in the operation of the fuel injection pump 2, in other words, the operation of the fuel injection.

The npn-type first transistor 25 and N-channel first and second MOS FETs 26 and 27 in the constant switching circuit 11 shown in FIG. 2 are merely examples, and other types It goes without saying that the circuit may be constituted by semiconductor elements.

[0023]

As described above, according to the present invention,
By making the so-called PID constant of the PID control circuit gradually change, so-called smooth switching of the PID constant becomes possible, and, unlike the conventional case, the operation state becomes unstable due to the switching of the PID constant. Instead, more appropriate operation control using PID control can be performed. Also, the switching element is called a PW
Since the resistor is equivalently gradually changed from the non-short-circuited state to the short-circuited state by performing on / off control using the M pulse signal, a relatively simple configuration is sufficient. In particular, in the invention according to claim 5, since the operation of the fuel injection pump does not become unstable due to the switching of the PID constant, the smoothness of the rotation operation of the engine is not impaired, and therefore, compared to the prior art. Thus, appropriate control of the engine rotation by more appropriate and widespread fuel injection control is realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration example of a fuel injection control device using a PID constant switching device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific circuit configuration example of a PID constant switching device.

FIG. 3 is a subroutine flowchart showing a procedure of PID constant switching control executed by a CPU.

FIG. 4 is an explanatory diagram for explaining a change in resistance value of a resistor of the PID control circuit shown in FIG. 2 together with a change in a pulse signal output from a port output terminal of a CPU;
4A is an explanatory diagram schematically showing a change in a pulse signal output from a port output terminal of a CPU, and FIG.
FIG. 9 is an explanatory diagram for explaining a substantial change in the resistance value of the resistor of the PID control circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Electric actuator 3a ... Electromagnetic coil 5 ... CPU 7 ... Comparator 8 ... PID control circuit 9 ... Electrification control circuit 10A ... PWM circuit 10B ... Drive transistor 11 ... Constant switching circuit

Continuing from the front page (72) Inventor Takuro Fujimori 3-13-26 Yaumicho, Higashimatsuyama-shi, Saitama Prefecture Inside of Xexel Higashimatsuyama Plant

Claims (6)

[Claims] 1. A switching element is connected in parallel to a desired resistor among a plurality of resistors connected in series as a PID constant of a PID control circuit, and the switching element is turned on.
By performing the off control, the composite resistance value of the plurality of resistors connected in series is equivalently and continuously changed, so that the switching of the PID constant from the predetermined value to the predetermined value is equivalently and gradually performed. A method for switching a PID constant, comprising: 2. The off / off control of a switching element is performed as follows.
2. The PID constant switching method according to claim 1, wherein the on / off interval becomes shorter as time elapses, and finally turns on. 3. A PID control circuit comprising a plurality of resistors connected in series as one of PID constants.
A PID constant switching device for switching a D constant, comprising: constant switching means connected to a predetermined resistor among the plurality of resistors, and for equivalently gradually changing the resistor from a non-short circuit state to a short circuit state. A PID constant switching device, comprising: 4. The constant switching means has a switching element connected in parallel to a predetermined resistor, and the on / off state of the switching element is controlled by a signal input from the outside. 4. The PID constant switching device according to claim 3, wherein the signal input from the outside is such that the on / off interval of the switching element becomes shorter as time elapses and finally turns on. . 5. A fuel injection control device for controlling operation of a fuel injection pump having an electronic governor using an electric actuator, wherein the fuel injection control device controls an operation amount of the electric actuator. A sensor to be detected is compared with a target value corresponding to a magnitude of a current to be supplied to the electric actuator in order to obtain a target operation amount of the electric actuator, and an output signal of the sensor. A comparator, and an energization control circuit that controls energization of the electric actuator at a repetition cycle corresponding to an output of the comparator, wherein the comparator has a PID control between an input terminal and an output terminal thereof. A circuit is provided to form a feedback loop, and the PID control circuit does not include a plurality of resistors connected in series as one of PID constants. A PID constant switching device connected to a predetermined one of the plurality of resistors and having constant switching means for equivalently gradually changing the resistor from a non-short-circuited state to a short-circuited state. A fuel injection control device comprising a PID constant switching device. 6. The constant switching means has a switching element connected in parallel to a predetermined resistor, and the on / off state of the switching element is controlled by a signal input from the outside. 6. The PID constant switching device according to claim 5, wherein the signal inputted from the outside is such that an on / off interval of the switching element becomes shorter as time passes and finally becomes an on state. A fuel injection control device comprising: