JPH1054290A - Control method and control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display an excellent control characteristic in every operating state by setting the initial value for initializing a second controller structure body depending on at least the target value and the actual value at the time of shifting from a first controller structure body to the second controller structure body. SOLUTION: An adjusting element 100 is controlled by an adjustment quantity setting part 110 supplied with an output signal ST of a switching means 120 for selecting either an output signal of a connecting point 125 or an output signal of a large signal controller 140. The switching means 120 is controlled by a control part 180 inputting the target value S and the actual value I. The connecting point 125 connects a P-control part 130 to an I-control part 135, and the P-control part 130 and I-control part 135 are selected by a switching means 150. An output signal of a zero value setting part 155 or a deviation signal between the target value S and actual value I from a connecting point 160 is inputted and processed, and the large signal controller 140 inputs the deviation signal of signals S, I.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an internal combustion engine, for example, for controlling the timing of fuel injection into an internal combustion engine, wherein a control deviation can be detected based on a target value and an actual value. The controller sets an adjustment amount to be applied to the adjustment element based on the control deviation, and when a first operating condition exists, the first controller structure is active and a second operating condition exists. At times, it relates to a control method in which the second controller structure is active, and a control device for implementing this method.

[0002]

2. Description of the Related Art Such a method and apparatus are disclosed in DE-O.
It is known from S3400711 (US Pat. No. 4,638,782). It describes, for example, a method and a device for controlling and / or regulating an adjusting element for controlling the fuel metering of an internal combustion engine. A control deviation is detected based on the target value and the actual value. The controller sets the adjustment amount to be supplied to the adjustment element based on the control deviation. At high rotational speeds, the control in this device is preferably performed by a controller with PI characteristics. In other operating states, for example when the rotational speed is low, only the control of the adjusting element is performed.

In order to be able to impose high demands on dynamic characteristics, for example, such a controller requires a complicated control circuit structure. One means for taking this requirement into account is to use a variable structure controller. In this case, different controller structures are switched under certain assumptions. For example, it is possible to switch between a PI controller and a proportional controller or pure control.

The problem here is the switching process. Switching from one controller structure to another often results in unwanted transients. When switching from a proportional controller with a large amplification factor, for example, used as a large signal controller, to a purely adaptive PI controller, for example, used as a small signal controller, the I component must be properly masked in advance. No. This is to avoid unwanted characteristics of the controller, especially oscillation.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method and a control device for an internal combustion engine of the type described at the outset, which provide good control characteristics in all operating states. It is.

[0006]

According to the present invention, there is provided, in accordance with the present invention, a method for initializing a second controller structure when transitioning from a first controller structure to a second controller structure. The problem is solved by setting the initial value at least depending on the target value and the actual value.

[0007]

The method and the device according to the invention have the advantage that good control characteristics are obtained in all operating states. No oscillations occur when transitioning between individual controller structures.

[0008]

1 shows a schematic diagram of the device according to the invention based on the control of an injection regulator of a self-igniting internal combustion engine. However, the present invention is not limited to this control. The invention can also be used, for example, for controlling other parameters of an internal combustion engine.

An embodiment is shown in the block diagram.
Fuel is metered from a fuel pump to an internal combustion engine (not shown). The start of fuel transfer or the start of fuel injection can be controlled by the injection regulator 100. This injection regulator 100
Is shown as an adjusting element 100 below.

The adjustment element 100 is supplied with a signal from an adjustment amount setting unit 110. Depending on the control signal generated by the adjustment amount setting unit 110, the adjustment element 100 takes a predetermined position. This means that a predetermined value is set for the start of injection or the start of conveyance.

The adjustment amount setting unit 110 includes a switch unit 12.
An output signal ST of 0 is supplied. The switch means 120 selects an output signal of the connection point 125 or an output signal of the large signal controller 140 and further conducts this signal to the adjustment amount setting unit 110. A connection point 125 connects the P control unit 130 and the I control unit 135. P control unit 130 and I control unit 135
Is supplied with an output signal of the switch means 150. P
The control unit 130 and the I control unit 135 form a so-called PI controller, and this PI controller can also be called a small signal controller.

The switch means 150 has a zero value setting unit 155.
Or the output signal of node 160 is further conducted to the PI controller. The output signal of node 160 is further provided to large signal controller 140.

The connection point 160 is supplied with the output signal S of the target value setting unit 170 with a positive sign and the signal I with a negative sign.
The signal I is the actual value and the signal S is the target value of the control circuit.

Further, a control unit 180 is provided. This controller processes the signals S and I and possibly further input quantities. The control unit 180 includes the switch means 150 and 12
The control signal is supplied to 0 and the signal is supplied to the I control unit 135.

Normally, the circuit is at the position shown by the solid line. In this case, the device operates as a small signal controller. Junction point 1
At 60, the target value S is compared with the actual value I. The control deviation thus formed is supplied to a controller including the P control unit 130 and the I control unit 135. Based on this control deviation, the P control unit 130 and the I control unit 135 respectively
It forms a component for the adjustment quantity supplied together at the junction 125. The adjustment amount ST thus formed is supplied to the adjustment amount setting section 110 via the switch means 120. The adjustment amount setting unit outputs the output signal of the controller to the adjustment element 10.
It is converted into a control signal to be applied to 0. Preferably, a duty ratio which depends on the control deviation is applied to the adjusting element 110. As a result, the adjusting element assumes a predetermined position and starts injection at a predetermined time.

As an actual signal I, on the one hand,
A position 0 or a signal relating to the start of transport and / or the start of injection can be used. Accordingly, the target value setting section 170 must set the corresponding target value S with the same configuration. The target value setting section 170 sets the target value S depending on various operation characteristic amounts not shown here.

If a large control deviation occurs, this may be the case, for example, when the target value S changes significantly, and the adjusting element requires a certain time before reaching a new target value. If the control deviation is large, the large signal controller 1
Activate 40. The control unit 180 depends on the control deviation.
Operates the switch means 150 and 120 to shift to the position shown by the broken line. This means that a signal is supplied from the zero value setting unit 135 to the I control unit 135 and / or the P control unit 130, and these control units maintain their states. The control deviation is supplied to the large signal controller 140. The output signal of the large signal controller is then supplied to the adjustment amount setting unit 110.

When the control deviation is larger than a predetermined value, a maximum value for the adjustment amount is set. If the control deviation is smaller than the negative threshold, a negative maximum value is set. Large signal controller 140 acts essentially as a two-point controller. In a region between the minimum value and the maximum value, the P control unit 130 and the I control unit 135 operate.

The problem here is the transition from the large signal controller to the P control unit 130 and the I control unit 135. That is, there is a problem that the switch means 150 and 120 shift from the position shown by the broken line to the position shown by the solid line.
During this transition, the I-control must be masked with appropriate initial values.

FIG. 2 shows a target value S, an actual value I, and an adjustment amount S.
T and the integral component IAN of the controller are plotted over time. The target value S is indicated by a dashed line, the actual value I is indicated by a broken line, the adjustment amount ST, that is, the input signal of the adjustment amount setting unit 110 is indicated by a solid line, and the integral component IAN is indicated by a dotted line.

Until time t1, all four signals have constant values. The switch means 120 and 150 assume the positions indicated by the solid lines. At time t1, the target value drops to a significantly lower value. Since the actual value is still at the original value, the control deviation becomes very large. The controller 180 recognizes this and controls the switch means 150 and 120 so that they assume the positions indicated by the broken lines. This activates the large signal controller 140. This means that the adjustment signal rises to a very high value.

The I control remains at the original value. I mean,
This is because controllers 130 and 135 have no further effect. Between the times t1 and t2, the actual value I drops significantly by a large adjustment amount ST. At time t2 the actual value I is
A value is reached such that the control deviation is less than the value at which the large signal controller 140 becomes active. This is at time t2
Means that the controllers 130 and 135 are again brought into their basic position by the switch means 120 and 150 and actuated.

At this point, the I-controller must now be initialized with the appropriate values. This means that the I-controller jumps to its new initial value at time t2.

From time t2, the actual value drops further and approaches the target value S. The adjustment amount ST drops greatly in a short time and approaches a new final value. The same holds true for the integral component. After time t3, all four values have reached their new final values.

FIG. 3 is a flow chart showing the means of the present invention. In a first step 300, the control unit detects a target value S, and in a step 310, detects the actual value I.
In step 320, the control unit calculates a control deviation R based on the target value S and the actual value I.

A query 330 then checks whether the absolute value of the control deviation | R | is greater than the threshold value SW. This threshold SW corresponds to the maximum possible control area. If it is larger than the threshold value, a control signal is output to the switch means 120 and 150 in step 340. This control signal causes the switch means to assume the position shown by the broken line. In this case, if the absolute value of the control deviation is large, the large signal controller 140 operates. Subsequently, at step 350, the marker M is set to 1. Subsequent to step 350, the process starts from step 300 with a new program progress.

Inquiry 330 determines that the control deviation is equal to threshold value SW
If not, step 360 is executed. In this step, it is checked whether or not the marker M is set by one. If not set, this means that the controllers 130 and 135 were already active in the previous program sequence, so that a new program sequence directly
It starts from 00. If the marker M is set to 1, this means that the large signal controller 140 was active in the preceding program result, and in step 370 the initial value IA for the I control 135 is set to the target value S, It is set as a function of the actual value I and the parameter WF.

Subsequently, at step 380, a control signal is output to the switch means 120 and 150. This causes the switch means to assume the position shown by the solid line. In this case, when the absolute value of the control deviation is small, the small signal controllers 130 and 135 are subactive.

The initial value IA for the integral component is obtained from the following equation.

IA = WF * S + (1-WF) * I The value WF is a first weighting factor. The value 1-WF is the second
Is a weighting coefficient. In the simplest embodiment, a constant value can be set as the weighting coefficient WF. This constant value is detected within the scope of application and is always used during operation. In an improved embodiment, the weighting factors are stored in a characteristic map depending on various operating parameters. The value S is the instantaneous target value, and the value I is the instantaneous actual value.
The calculation of the initial value IA for the integral component IAN is performed based on the instantaneous value of the target value and the actual value.

In a particularly advantageous configuration, the weighting factor WF
Is set depending on the target value S, the actual value I, and the threshold value SW. The threshold value SW corresponds to the control deviation when switching from the small signal control unit to the large signal control unit.

This means that a weighted deviation WF is introduced, which represents the extent of the control deviation in relation to the maximum efficiency range of the small signal controller. Depending on this weighting, the I-control is masked by a value that depends on the target value and the actual value. Therefore, the optimum initial value of the integrator of the I control unit is obtained depending on the operating condition that exists instantaneously.
The selection of the weighting factors ensures that the start to a new structure when the instantaneous control deviation is at a maximum leads to a masking of the integral component with the maximum allowable servo component of the entire system, ie with the maximum dynamics. In addition, when starting a new structure, if the control deviation can be ignored,
It is assured that the control of the adjustment quantity operates gently. All intermediate states are continuously adapted, which fully satisfies the requirements for seamless method steps.

Another embodiment of the present invention is shown in the flowchart of FIG. In a first step 400, the control unit detects the target value S, and in a step 410, detects the actual value I. In step 420, the control unit calculates the control deviation R based on the target value S and the actual value I.

A query 430 then checks whether the absolute value of the control deviation | R | is greater than the threshold value SW. If so, a control signal is output to switch means 120 and 150 in step 440. This causes the switch means to assume the position indicated by the broken line. In this case, if the absolute value of the control deviation is large, the large signal controller 140 is active. At step 450, the marker M is set by one. Continue with step 4
At 55, the difference between the integral component and the target value S is detected and the value RA
Is stored as Subsequent to step 455, a new program flow starts from step 400.

Inquiry 430 determines that the control deviation is equal to threshold value SW
If not, step 460 is performed. In this step, it is checked whether or not the marker M is set by one. If it is not set, this means that
This means that 30 and 135 were already active, and a new program sequence is started directly from step 400. If marker M is set by 1,
This means that the large signal controller 14
0 means active, step 470
The initial value IA for the I-control unit 135 is determined by the function F of the instantaneous target value S and the deviation RA of the integral component IAN from the target value S.
Is set as These values are stored when transitioning from the small signal controller to the large signal controller.

Subsequently, at step 480, a control signal is output to the switch means 120 and 150. This causes the switch means to assume the position shown by the solid line.
In this case, if the absolute value of the control deviation is small, the small signal controllers 130 and 135 are active.

The initial value for the I control unit IA is obtained from the following equation in a simple embodiment.

IA = S + RA According to the present invention, when shifting from the small signal characteristic to the large signal characteristic, the difference between the integral component IAN and the target value S is detected, and this value RA is stored. When transitioning from the large signal characteristic to the small signal characteristic, the stored value RA and the instantaneous target value S
, A new initial value for the integral component IAN is determined. This means that after the initial value for the initialization of the small signal controller has changed from the large signal controller to the small signal controller, at least the instantaneous desired value and the stored deviation between the integral component and the desired value. Means that the setting can be made when shifting from the small signal controller to the large signal controller based on the above.

It is particularly advantageous to determine the initial value according to the following equation:

IA = WF * S + (1-WF) * I + RA This means that the stored value RA is added to the initial value determined in the method step shown in FIG.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of the device of the present invention.

FIG. 2 is a diagram showing various signals over time.

FIG. 3 is a flowchart illustrating the method of the present invention.

FIG. 4 is a flowchart for explaining the method of the present invention.

[Explanation of symbols]

 Reference Signs List 100 Injection regulator 110 Adjustment amount setting unit 120, 150 Switch means

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kai-Rals Barbechen Germany Germany Ludwigsburg Hospital Strasse 7

Claims (10)

[Claims] 1. A control method for an internal combustion engine, for example, for controlling the time point of fuel injection into an internal combustion engine, wherein a control deviation can be detected based on a target value (S) and an actual value (I). The controller sets an adjustment amount to be applied to the adjustment element based on the control deviation; when a first operating condition exists, the first controller structure is active, and a second operating condition exists. And in the control method wherein the second controller structure is active, when the transition from the first controller structure to the second controller structure initializes the second controller structure. A control method, wherein the initial value is set at least depending on the target value and the actual value. 2. When transitioning from the first controller structure to the second controller structure, initial values for initializing the second controller structure are set to at least an instantaneous target value and an instantaneous value. 2. The method according to claim 1, wherein the setting is made dependent on the actual value of. 3. The method according to claim 1, wherein the initial value is set based on a target value weighted by a first weighting factor and an actual value weighted by a second weighting factor. 4. The method according to claim 1, wherein the weighting coefficient is set based on a control deviation and / or a maximum control range (SW).
The method according to any one of claims 1 to 3. 5. The method according to claim 1, wherein the first controller structure is configured as a large signal controller and the second controller structure is configured as a small signal controller. Method. 6. The controller of claim 1, wherein the second controller structure comprises a controller, the controller having at least one I-control.
The method according to any one of claims 1 to 5. 7. When transitioning from the first controller structure to the second controller structure, an initial value for initializing the second controller structure is set to at least an instantaneous target value, and 7. The method according to claim 1, comprising setting the transition from the second controller structure to the first controller structure depending on the deviation between the integral component and the desired value. . 8. An initial value (IA) is set according to the following equation: IA = WF * S + (1-WF) * I where parameter WF is a first weighting factor, and parameter 1-WF is a second weighting factor. 8. The method according to claim 1, wherein parameter S is a target value and parameter I is an actual value. 9. An absolute value of the control deviation is in a maximum control region (S
9. A method according to claim 1, wherein a first operating state is present when W is greater than W), and a second operating state is present when the absolute value of the control deviation is smaller than the maximum control area (SW). The method of claim 1. 10. A control device for an internal combustion engine, for example, for controlling the time of fuel injection into an internal combustion engine, wherein a control deviation can be detected based on a target value and an actual value, and the controller controls the control deviation. Setting an adjustment amount to be applied to the adjustment element based on the first and second control means, wherein the switch means activates the first controller structure when the first operating state is present, A control device of the type operating a second controller structure in the presence of the operating state of the second controller structure, wherein the second controller structure is switched from the first controller structure to the second controller structure. A control device comprising means for setting an initial value for a structure at least depending on a target value and an actual value.