JPH0533700Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for a variable displacement turbocharger.

[Prior art] A plurality of guide vanes are provided on the inlet side of the turbine of a turbocharger, and when the engine speed is low, the opening degree of the guide vanes is reduced to narrow the area of the nozzle formed by the guide vanes, and when the engine speed is high, the area of the nozzle formed by the guide vanes is narrowed. A control device for a variable displacement turbocharger is known (for example, Japanese Utility Model Application No. 111324/1983), which controls the area of the nozzle to be increased in proportion to the area of the nozzle.

By the way, there is also known a control device that controls the opening degree of the guide vane based on engine rotation and load, and this will be explained with reference to FIG. 5.

The compressor 3 of the turbocharger 2 connected to the engine 1 is provided with a supercharging pressure sensor 4 which is a supercharging pressure detection means and outputs a measured voltage Vb.
The turbine 5 is provided with a vane actuator 6, which is a variable capacity control means for changing the opening degree of a guide vane (not shown).

The control circuit, generally designated by 20, includes a determination circuit 21 that determines the target boost pressure based on signals from the engine rotation sensor 7 and the load sensor 8 and outputs a reference voltage Va; , a comparison circuit 22 that compares the actual measurement value voltage Vb from the boost pressure sensor 4, a control amount calculation circuit 23 that calculates a control amount based on the comparison result of the comparison circuit 22, that is, voltage Va−Vb=Vc, and an amplification It consists of a circuit 24.

To control such a control device, PID control, so-called learning control method, is generally used based on the following calculation formula. That is, Yn=KP・ΔXn+Σ(KI・ΔXn)+KD(Xn−Xn−1) () Here, Yn: Controlled amount at that time Xn: Target value at that time Xn−1: Target value before 1 digital amount ΔXn: Difference between the actual measured value and the target value at that time KP: Proportional constant KI: Integral constant KD: Differential constant By the way, since the feedback reaction from the boost pressure sensor 4 is slow, ΔXn in equation () becomes large. Accordingly, Yn also increases. This results in so-called over-control, as shown by the chain line in Figure 6.
It is not possible to follow the change in the target boost pressure shown by the solid line, and the actual boost pressure causes hunting, resulting in a decrease in control accuracy.

[Object of the invention] Therefore, an object of the invention is to provide a control device for a variable displacement turbocharger that improves control accuracy.

[Configuration of the invention] According to the variable displacement turbocharger control device of the invention, the target supercharging determines the target supercharging pressure based on the detection signals of the engine rotation sensor 8 and the engine load sensor 9 and outputs the reference voltage Va. pressure determination circuit 11, the reference voltage Va and supercharging pressure detection means 4
Comparison circuit 1 to find the difference Vc from the measured voltage Vb from
2, a first supercharging state determining circuit 13 and a second supercharging state determining circuit 14 that determine the supercharging state based on the voltage difference Vc, and a reference control amount for obtaining the target supercharging pressure. A reference control amount application circuit 15 outputs a signal determined from a three-dimensional map with engine rotation and load as parameters, and a maximum control amount signal is output based on the judgment result of the first supercharging state judgment circuit 13. When the difference between the target value and the actual measurement value is large based on the judgment results of the maximum control amount application circuit 16 and the second supercharging state judgment circuit 14, a constant is applied to the reference control amount from the reference control amount application circuit 15. a controlled variable correction circuit 17 that adds or subtracts the maximum controlled variable; a controlled variable calculation circuit 18 that adds or subtracts the reference controlled variable according to the theoretical learning correction amount when the difference between the target value and the measured value is small; It consists of an amplifier circuit 19 that outputs to the vane actuator 6 based on the output signals from the application circuit 16, the control amount correction circuit 17, and the control amount calculation circuit 18. Difference Vc between Va and measured voltage Vb
is large, it is output to the maximum control amount application circuit 16, and the second supercharging state judgment circuit 14
It is determined whether Vc is larger or smaller than a value smaller than the judgment value of the second supercharging state judgment circuit 13, and when it is large, it is output to the control amount correction circuit 17, and when it is small, it is output to the control amount correction circuit 17. It is designed to be output to the control amount calculation circuit 18.

[Operation and effect of the invention] Therefore, the supercharging state is determined based on the magnitude of the difference between the judgment pressure and the detected pressure, and when the difference is large, the maximum control amount is used to bring it as close to the target value as possible, and the difference becomes smaller. By correcting the reference control amount or adding a value by an arithmetic circuit in accordance with this, it is possible to quickly bring the actual boost pressure closer to the target boost pressure. As a result, hunting of the actual boost pressure can be reduced and control accuracy can be improved.

[Examples] Examples of the present invention will be described below with reference to the drawings.

Portions in FIG. 1 that correspond to those in FIG. 5 are given the same reference numerals and redundant explanation will be omitted.

In FIG. 1, a control circuit generally designated by 10 includes a determination circuit 11 that determines a target boost pressure based on detection signals from an engine rotation sensor 8 and an engine load sensor 9 and outputs a reference voltage Va, and a determination circuit 11 that outputs a reference voltage Va.
Difference between Va and actual measured voltage Vb from boost pressure sensor 4
A comparison circuit 12 that determines Vc, and a first supercharging state determination circuit 1 that determines the supercharging state based on the voltage difference Vc.
3 and the second supercharging state judgment circuit 14, and outputs a signal obtained from a three-dimensional map with engine rotation and load as parameters, which has a built-in reference control amount that allows the target supercharging pressure to be obtained in the standard state of the engine. A maximum control amount application circuit 16 that outputs a maximum control amount signal based on the determination result of the reference control amount application circuit, so-called learning circuit 15, and the first supercharging state determination circuit 13.
, a control amount correction circuit 17 that corrects the reference control amount from the reference control amount application circuit 15 based on the judgment result of the second supercharging state judgment circuit 14, and a control amount calculation circuit that performs calculations on the reference control amount. It consists of a circuit 18 and an amplifier circuit 19 that amplifies the output signals from these circuits 16, 17, and 18 and outputs the amplified signals to the vane actuator 6.

During control, as schematically shown in FIG. 2, when the difference between the target value (indicated by a solid line) and the actual value (indicated by a chain line) is large, the control circuit 10 uses maximum control to bring it as close to the target as possible (region). When the difference reaches a certain value, the amount of control relative to the target is suppressed (region), and when the difference becomes smaller, feedback is applied to achieve fine control without over-controlling (region). Control accuracy can be improved by reducing hunting.

The aspect of this control will be explained in detail. Figure 3 shows the judgment area amounts W3, W1 (minus side) that are on the minus side or plus side with respect to the target value Xn at that time,
A judgment area defined by W4 and W2 (plus side) is provided, and depending on which area the difference ΔXn between the actual measured value and the target value is at that time,
The control amount Yn is taken as shown in FIG.

That is, when the difference ΔXn is in the region ΔXn≧W1, that is, Yn=100% (maximum positive control amount); when the difference ΔXn is in the region ΔXn≦W2, that is, Yn=0% (maximum negative control amount) W3≧ΔXn >W1, that is, when in the region, Yn=Dn+A, where Dn: Theoretical control amount that gives the target value of B Here, B: Correction amount of Dn (constant) As mentioned above, when there is a difference ΔXn in the area, ,,, the control amount Yn is corrected by the positive and negative maximum control amount or correction amount A or B, and in this case is controlled by the output from the control amount correction circuit 17.

In other words, when in the region W4>ΔXn>W3, Yn=Dn+KP・ΔX+KIΣΔX () This is the theoretical learning control amount corresponding to equation ().

That is, in the region, since the difference ΔXn is small, the control amount Yn is controlled by the output from the control amount calculation circuit 18.

Therefore, A1: Judgment supercharging pressure − 200 mmHg equal applied voltage (quantity W1
) A2: Judgment boost pressure Equal applied voltage of 300mmHg (quantity W2
) B1: Judgment boost pressure −50mmHg equal applied voltage (quantity
Compatible with W3) B2: Judgment supercharging pressure 70mmHg equal applied voltage (quantity W2
) and control as follows.

That is, the first supercharging state determination circuit 13 determines whether Vc≦A1 or Vc≧A2, and if YES, the maximum control amount application circuit 16 outputs the Theoretical control amount by output
Control Yn=100% or 0%. Then, when the above judgment becomes NO, that is, when the amount W1 or W2 is reached, the second supercharging state judgment circuit 14
Then, it is determined whether Vc≦B1 or Vc≧B2. If YES, the control amount correction circuit 17 controls the control amount Yn, which is the theoretical control amount Dn based on the map from the reference control amount application circuit 15 plus the correction amount A or minus the correction amount B.
Then, when the above judgment becomes NO, that is, when the amount W3 or the amount W4 is reached, that is, when the area is entered, the controlled amount calculation circuit 18 calculates the controlled amount Yn using the formula (), and performs so-called learning control. It is. In this state, the actual boost pressure is close to the target value, so changes can be predicted and control can be performed with high accuracy.

[Effects of the invention] As described above, according to the invention, when the difference between the target value and the actual measurement value is large, control is performed using the control amount correction circuit that corrects the control amount Yn with the correction amount A or B, which reduces the calculation work. can be controlled in a shorter time than In general, arithmetic processing slows down the time for action and reaction with respect to the amount of control, so if the amount of control is large, there will be a delay in actual control. However, in the present invention, since the arithmetic processing is performed within a narrow range, there is no delay and no oscillation occurs. Therefore, highly accurate control is possible. That is,
According to the present invention, when the control amount is large, arithmetic processing causes time delays and hunting, but by processing this with a control amount correction circuit that corrects this with a correction amount, accurate and precise control can be achieved. It is.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention;
Fig. 2 is a control characteristic diagram that outlines the effects of the present invention, Fig. 3 is an explanatory diagram of the determination area, Fig. 4 is a control characteristic diagram that explains the effects of the present invention in detail, and Fig. 5 is a conventional device. FIG. 6 is a diagram showing its control characteristics. 4...Supercharging pressure sensor, 6...Vane actuator, 10...Control circuit, 11...Judgment circuit, 1
2... Comparison circuit, 13... First supercharging state determining circuit, 14... Second supercharging state determining circuit, 15...
Reference control amount application circuit, 16... Maximum control amount application circuit, 17... Controlled amount correction circuit, 18... Controlled amount calculation circuit.

Claims (1)

[Scope of utility model registration request] Target boost pressure determination circuit 11 that determines target boost pressure based on detection signals of engine rotation sensor 8 and engine load sensor 9 and outputs reference voltage Va.
, a comparison circuit 12 that calculates the difference Vc between the reference voltage Va and the measured voltage Vb from the supercharging pressure detection means 4, and a first supercharging state determination circuit that determines the supercharging state based on the voltage difference Vc. 13 and a second supercharging state determination circuit 14, and a reference control amount application circuit that outputs a signal determined from a three-dimensional map with engine rotation and load as parameters, which contains a reference control amount to obtain a target supercharging pressure. 15, a maximum control amount applying circuit 16 that outputs a maximum control amount signal based on the judgment result of the first supercharging state judgment circuit 13, and a target control amount application circuit 16 that outputs a signal of the maximum control amount based on the judgment result of the second supercharging state judgment circuit 14. A control amount correction circuit 17 that adds or subtracts a constant to the reference control amount from the reference control amount application circuit 15 when the difference between the target value and the actual measurement value is large, and a control amount correction circuit 17 that adds or subtracts a constant to the reference control amount from the reference control amount application circuit 15 when the difference between the target value and the actual measurement value is small; Controlled amount calculation circuit 18 that performs addition and subtraction to the controlled amount according to the theoretical learning correction amount.
and an amplifier circuit 19 that outputs an output signal to the vane actuator 6 based on the output signals from the maximum control amount application circuit 16, the control amount correction circuit 17, and the control amount calculation circuit 18. Judgment circuit 1
3 outputs to the maximum control amount application circuit 16 when the difference Vc between the reference voltage Va and the measured voltage Vb is large, and the second supercharging state judgment circuit 14 outputs it to the maximum control amount application circuit 16 when the voltage difference Vc is large. It is determined whether the value is larger or smaller than the judgment value of the supply state judgment circuit 13, and if it is large, it is output to the control amount correction circuit 17, and if it is small, it is output to the control amount calculation circuit 18. A variable displacement turbocharger control device characterized by: