JP2011001871A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device which prevents the occurrence of hunting to be caused when abrupt disturbance occurs.SOLUTION: In this control device for controlling an internal combustion engine or a device incidental to it to let its output to follow a target value r, this control device performs moderating control to the target value rof the output to be controlled or its deviation being referred to by a servo controller and suppresses the fluctuation of an input to be controlled in accordance with fluctuation of the target value r, namely, an amount of operation of an operation part when the control device detects the situation where abrupt disturbance occurs.

Description

  The present invention relates to a control device for controlling an internal combustion engine or a device attached thereto.

  An exhaust gas recirculation system disclosed in Patent Document 1 below controls an EGR rate (or EGR amount) of an internal combustion engine equipped with a supercharger. There is a mutual interference between the EGR rate and the supercharging pressure, and it is difficult to simultaneously control both the EGR rate and the intake pipe pressure (or intake air amount) with a one-input one-output controller. In addition, the responsiveness varies depending on the operation region of the internal combustion engine, and the turbocharger has a turbo lag (dead time). Under such circumstances, the system described in Patent Document 1 employs sliding mode control, which is an effective control method for a non-linear control target, and designs a multi-input multi-output controller that takes into account the interaction. I have control.

  When designing a sliding mode controller, it is considered to derive one switching hyperplane from a specific state space model called a nominal model and to keep the state in this hyperplane. That is, a single controller designed off-line is applied to the entire operation region. Of course, in an actual automobile, the driving region changes every moment, but the sliding mode controller can absorb the error (perturbation) between the actual driving region and the nominal point as a disturbance.

  That said, not every disturbance can be absorbed. The calculation cycle of the controller is greater than 0, and the opening and closing speeds of the EGR valve, variable turbo nozzle vane, and the like serving as the operation unit are also finite. Unless the disturbance can be absorbed by the width that the valve opens and closes during a predetermined calculation cycle, suppression control cannot be performed.

  During the acceleration of the automobile, the engine speed and the required fuel injection amount increase, and the work of the exhaust turbo increases. Therefore, even if the operation part is not opened / closed at all, the pressure in the intake pipe naturally increases. A controller that does not directly refer to the engine speed and the fuel injection amount treats such fluctuations in the intake pipe pressure as disturbances. When the driver relaxes the accelerator and the acceleration is completed, the engine speed and the fuel injection amount decrease. Usually, the target value of the intake pipe pressure depends on the engine speed and the fuel injection amount, and this target value decreases with the end of acceleration. In addition, if the engine speed and the fuel injection amount are reduced, the work of the exhaust turbocharge is reduced, so that a sudden decrease in the intake pipe pressure also occurs.

  As a result, a decrease in the intake pipe pressure as an abrupt disturbance due to a decrease in the engine speed and the fuel injection amount is added to the decrease in the intake pipe pressure caused by the opening / closing of the operation unit corresponding to the target value decrease. Then, an undershoot in which the pressure in the intake pipe drops greatly, and an overshoot that jumps up greatly in the subsequent reaction, which may cause a hunting state in which the vertical movement is repeated. Hunting of the intake pipe pressure is not preferable because it causes hunting of the EGR rate that is coordinated and hunting of the opening of each valve, leading to a decrease in drivability and deterioration of exhaust gas.

JP 2007-032462 A

  The present invention, which has been made by paying attention to the above-mentioned problem for the first time, is intended to be able to prevent hunting caused when a sudden disturbance occurs.

  In the present invention, the control output related to the internal combustion engine or the device attached thereto is controlled to follow the target value, and the control input is repeatedly calculated based on the deviation between the control output and the target value. Servo controller, and the actual value of the state quantity of the plant related to the control output (related to the control output via the observation equation (output equation)) and the control input are substituted into the plant model and calculated The target value or deviation of the control output referred to by the servo controller when a hunting condition including at least the condition that the amount of change per unit time of the difference from the calculated value of the state quantity exceeds a predetermined threshold is established A control device is provided that includes a target correction unit that performs annealing.

  That is, when a situation in which a sudden disturbance occurs is detected, the target value of the control output to be controlled or its deviation is smoothed, and the control input fluctuation due to the target value fluctuation, in other words, the operation unit The operation amount was suppressed. This makes it possible to prevent hunting caused when a sudden disturbance occurs.

  In particular, in a control system that controls an internal combustion engine equipped with a turbocharger and includes the intake pipe pressure or intake air amount in the control output, the intake pipe pressure or intake Smooth the target value of quantity. That is, since the supercharging pressure naturally decreases as a disturbance after the end of acceleration, the intake pipe pressure or the intake air amount is controlled to be reduced without operating the operating unit.

  A map that defines a relationship between an index value related to the current status of the internal combustion engine or the device attached thereto and a target value of the control output is stored in advance, and the control output is obtained by searching the map using the index value as a key. As long as the target value is known, the disturbance that can be absorbed by the controller can be controlled by setting the target value corresponding to the index value. Only for sudden disturbances that cannot be absorbed, the target value that rises and falls according to the index value is subjected to a smoothing process to suppress hunting.

  The index value includes the number of revolutions of the internal combustion engine and the fuel injection amount (or required load), and the hunting condition includes that both the number of revolutions of the internal combustion engine and the fuel injection amount tend to decrease. If so, control of the intake pipe pressure or intake air amount after the end of acceleration can be suitably performed.

  It may be added to the hunting condition that the accelerator depression amount tends to decrease. This is because a decrease in the accelerator depression amount results in a decrease in vehicle speed and a decrease in engine speed, which is also a disturbance factor.

  According to the present invention, it is possible to prevent hunting caused when a sudden disturbance occurs.

The hardware resource block diagram of the EGR system in one Embodiment of this invention. Configuration explanatory drawing of the control apparatus of the embodiment. The block diagram of the adaptive sliding mode controller of the embodiment. The block diagram of the target correction | amendment part of the embodiment. The chart which shows the correlation with the vehicle speed of a motor vehicle, the pressure in an intake pipe, and its disturbance. The chart which shows the pattern of hunting caused by disturbance. The chart which illustrates the smoothing process of the target value of the intake pipe pressure. The flowchart which shows the procedure of the process which the control apparatus of the embodiment performs.

  An embodiment of the present invention will be described with reference to the drawings. What is shown in FIG. 1 is an EGR system that is one of the objects to which the present invention is applied. The EGR system incidental to the internal combustion engine 2 includes measuring devices 11 and 12 for detecting values related to a plurality of fluid pressures or flow rates in the intake and exhaust systems 3 and 4, and setting target values to these values. ECU (Electronic Control Unit) 5 which is a control device for operating a plurality of operation units 45, 42, 33 in order to follow the target value.

  The internal combustion engine 2 is a diesel engine equipped with a supercharger, for example. The intake system 3 of the internal combustion engine 2 is provided with a variable turbo compressor 31 and an intercooler 32 for intake air cooling and a D throttle valve 33 for adjusting the amount of fresh air downstream thereof. In addition, a flow meter 11 that measures the amount of fresh air and a pressure meter 12 that measures the pressure in the intake pipe are installed.

  A turbine 41 for driving the compressor 31 is disposed in the exhaust system 4 of the internal combustion engine 2, and a nozzle vane 42 for increasing or decreasing the A / R ratio of the supercharger is provided at the inlet of the turbine 41. Then, an EGR passage 43 for recirculating a part of the exhaust gas discharged from the combustion chamber of the internal combustion engine 2 to the intake system 3 is formed. The EGR passage 43 is connected downstream of the throttle valve 33 in the intake system 3. The EGR passage 43 is provided with an EGR cooler 44 for cooling the exhaust, and an external EGR valve 45 that adjusts the amount of exhaust gas (EGR gas) that passes therethrough.

  In the present embodiment, a target value is set for each of the EGR rate (or EGR amount) and the intake pipe pressure (or intake air amount), and a plurality of operation units are set so that both control amounts are directed toward the target value. That is, control for operating the EGR valve 45, the variable turbo nozzle 42 and the throttle valve 33 is performed.

  The EGR valve 45, the nozzle vane 42, and the throttle valve 33 are controlled by the ECU 5 to change their opening degrees linearly. Each operation unit 45, 42, 33 is combined with an electric valve that changes the opening by increasing or decreasing the duty ratio of the drive signal, or a vacuum control valve, etc. It uses mechanical valves that change.

  The ECU 5 is a microcomputer including a processor, a RAM (Random Access Memory), a ROM (Read Only Memory) or a flash memory, an A / D conversion circuit, a D / A conversion circuit, and the like. In addition to the measuring instruments 11 and 12 for detecting the EGR rate and the pressure in the intake pipe, the ECU 5 detects various measuring instruments for detecting the engine speed, the amount of depression of the accelerator pedal, the cooling water temperature, the intake air temperature, the outside air temperature, etc. (Not shown) can be electrically connected to each other to receive signals output from these measuring instruments to obtain each value.

Incidentally, in this embodiment, the EGR rate is not directly measured. The amount of air entering the cylinder of the internal combustion engine 2 can be predicted based on the nozzle opening of the variable turbo. The predicted value of the air amount g _cyl Distant, if the fresh air amount measured by the flow meter 11 is denoted by g _a, the estimated EGR rate _{e egr, e egr = 1-} g a / g cyl the relationship is established To do. The ROM or flash memory of the ECU 5 stores in advance map data that defines the relationship between the variable turbo nozzle opening and the amount of air entering the cylinder. The ECU 5 searches the map using the nozzle opening of the variable turbo as a key, obtains a predicted value of the amount of air entering the cylinder, and substitutes this and the new amount of air into the above formula to calculate the EGR rate.

  In addition, the ECU 5 is electrically connected to the EGR valve 45, the variable turbo nozzle 42, the throttle valve 33, an injector for controlling fuel injection, a fuel pump, and the like (not shown), and signals for driving them. Can be entered.

  A program to be executed by the ECU 5 is stored in advance in a ROM or a flash memory, and is read into the RAM at the time of execution and is decoded by the processor. The ECU 5 controls the internal combustion engine 2 according to a program. For example, the required fuel injection amount (in other words, engine load) is determined based on various conditions such as engine speed, accelerator pedal depression amount, and coolant temperature, and a drive signal corresponding to the required injection amount is input to an injector or the like. And control the fuel injection. The ECU 5 then functions as the servo controller 51 and the target correction unit 52 shown in FIGS. 2 to 4 according to the program.

  The servo controller 51 is a sliding mode controller and is responsible for the sliding mode control of the EGR rate and the intake pipe pressure. During feedback control, the ECU 5 receives signals output from various measuring instruments (not shown), and knows the engine speed, accelerator depression amount, cooling water temperature, intake air temperature, external temperature and pressure, etc., and the required injection amount To decide. Subsequently, the target EGR rate and the target intake pipe pressure are set based on at least the engine speed and the required injection amount. The ROM or flash memory of the ECU 5 stores in advance map data indicating each target value to be set according to the engine speed and the required injection amount. The ECU 5 searches the map using the engine speed and the required injection amount as keys, and obtains target values for the EGR rate and the intake pipe pressure. Further, the target value obtained by referring to the map is set as a basic value, and this is corrected according to the cooling water temperature, the intake air temperature, the outside air temperature, the atmospheric pressure, and the like to obtain the final target value.

  Then, the ECU 5 receives signals output from the measuring instruments 11 and 12 to obtain the current values of the EGR rate and the intake pipe pressure, and the opening of the EGR valve 45 from the deviation between the current value of each control variable and the target value. Then, the opening degree of the variable turbo nozzle 42 and the opening degree of the throttle valve 33 are calculated, and a drive signal corresponding to each operation amount is input to the operation units 45, 42, 33 to operate the opening degree.

  A supplementary explanation will be given regarding adaptive sliding mode control of the EGR rate. The state equation and the output equation are as shown in the following equation (Equation 1).

  In this embodiment, the state quantity vector X has a structure that can be directly obtained from the output vector Y. In other words, a value that can be detected via the measuring instruments 11 and 12 is directly controlled, so that the state estimation observer. This prevents the deterioration of the control performance due to the estimation error. The output matrix C is known, and is a unit matrix in this embodiment.

  In plant modeling, that is, identification of the coefficient matrix A and the input matrix B in the state equation (Equation 1), the opening degree is manipulated by inputting M-sequence signals having various frequencies to the operation units 45, 42, and 33. Then, the values of the EGR rate and the intake pipe pressure are observed, and the matrices A and B are identified from the input / output data. It is assumed that the M-sequence signals input to the operation units 45, 42, and 33 are uncorrelated with each other. This makes it possible to create a model that takes into account the mutual interference between the values.

FIG. 3 shows a block diagram of the adaptive sliding mode control system of the present embodiment. The design procedure of the sliding mode controller 51 includes the design of the switching hyperplane and the design of a nonlinear switching input for constraining the state quantity to the switching hyperplane. If a new state quantity vector _Xe is defined by adding an integral value vector Z of the deviation between the target value vector R and the output vector Y to the original state quantity vector X in order to constitute a type 1 servo system, The equation of state of the expanded system shown in (Expression 2) is obtained.

  In consideration of the stability margin, the design method using the zero of the system is used to design the switching hyperplane. That is, the hyperplane is designed so that the equivalent control system is stable when the expansion system of the above equation (Equation 2) is generating the sliding mode. When the switching function σ is defined by Expression (Expression 3), σ = 0 and Expression (Expression 4) holds when the state is constrained to the hyperplane.

  Therefore, the linear input (equivalent control input) when the sliding mode occurs is expressed by the following equation (Equation 5).

  Substituting the linear input of the above equation (Equation 5) into the state equation (Equation 2) of the expanded system results in an equivalent control system of the following equation (Equation 6).

  Since designing a hyperplane so that this equivalent control system is stable is equivalent to designing a system ignoring the target value R, the following equation (Equation 7) holds.

  Taking the stability ε into consideration for the system of the above equation (Equation 7), obtaining the feedback gain using the optimal control theory, and making it a hyperplane, the following equation (Equation 8) is obtained.

The matrix P _s is a positive definite solution of the Riccati equation (Equation 9).

Q _s in the Riccati equation (Equation 9) is a weight matrix for control purposes, and is a non-negative definite symmetric matrix. q ₁ and q ₂ are weights for the integral Z of the deviation, and are determined by the difference in the speed of the frequency response of the control system. q ₃ and q ₄ are weights for the output Y, and are determined by the difference in the magnitude of the gain. Further, R _s in the Riccati equation (Equation 9) is a weight matrix of the control input and is a positive definite symmetric matrix. ε is a stability margin coefficient and is specified so that ε ≧ 0.

  Instead of the above equations (Equation 8) and (Equation 9), the following discrete hyperplane construction equation (Equation 10) and algebraic Riccati equation (Equation 11) may be used.

The final sliding mode method is used to design the input for constraining to the hyperplane. Here, the control input U is expressed by the following expression (Equation 12) as the sum of the linear input U _eq and a new input, that is, a nonlinear input (nonlinear control input) U _nl .

  Since it is desired to stabilize the switching function σ, the Lyapunov function for σ is selected as shown in the following equation (Equation 13) and differentiated to obtain the equation (Equation 14).

  Substituting the equation (Equation 12) into the equation (Equation 14) yields the following equation (Equation 15).

When the nonlinear input U _nl to the following expression (Expression 16), the derivative of the Lyapunov function becomes equation (17).

  Therefore, if the switching gain k is positive, the differential value of the Lyapunov function can be negative, and the sliding mode is guaranteed. The control input U at this time is expressed by the following equation (Equation 18).

  η is a smoothing coefficient introduced to reduce chattering, and η> 0.

  In the sliding mode control, it is necessary to increase the nonlinear gain in order to constrain the state quantity to the hyperplane. However, if the nonlinear gain is increased, chattering occurs in the control input. Therefore, the uncertainty of the model is divided into a definite part whose structure is unknown and whose parameter is unknown, and an uncertain part whose structure is unknown but whose upper bound is known. Uncertainty (f + Δf) is added to the state equation (Equation 1), and is expressed by the following equation (Equation 19).

  The uncertainty determination part f is compensated by identifying the unknown parameter θ. In this case, the switching gain is applied only to the uncertain part Δf of the uncertainty, and the chattering of the control input can be greatly reduced as compared with the case where the switching gain is applied to the entire uncertain component (f + Δf).

The control input U is represented by the following equation (Equation 20) obtained by adding the adaptive term U _ad to the equation (Equation 18).

Γ _{1 at the} control input (Equation 20) is an adaptive gain matrix. The function h is generally a function of the state quantity x and / or the unknown parameter θ. However, in the present embodiment, by making h a simple expression and a constant unrelated to x and θ, x is quickly converged, and θ To increase the adaptation speed. In particular, when h = 1, the estimated parameter can be identified according to the following equation (Equation 21).

In the present embodiment, the EGR ratio y ₁ and the intake pipe pressure y ₂ as a control output variable, the opening degree u ₁ of the EGR valve 45, the opening degree u ₃ of opening u ₂ and the throttle valve 33 of the variable turbo nozzle 42 Performs 3-input 2-output feedback control using control input variables. The number of state variables (system order) is 2 in the initial system (Equation 1), and 4 in the expanded system (Equation 2). By specifying the control output and the state quantity in this way, there is no need to install a measuring instrument such as a flow meter at a location where it directly contacts the exhaust gas.

However, in a three-input two-output system as in this embodiment, det (SB _e ) = 0 holds, and the matrix (SB _e ) is not regular. Therefore, the inverse matrix (SB _e ) ⁻¹ is calculated as a generalized inverse matrix. As the generalized inverse matrix, for example, a Moore-Penrose-type inverse matrix (SB _e ) ^† is used.

  As already described, when the sliding mode controller 51 is designed, a model (matrix A, matrix A) of the internal combustion engine 2 under a specific operating region, that is, a specific engine speed and a required fuel injection amount (required load). B) is identified, the state equation (Equation 2) is obtained from the nominal model, and the switching hyperplane S is derived. In an actual automobile, the driving region changes every moment, but the sliding mode controller can absorb the perturbation between the actual driving region and the nominal point as a disturbance.

  A system in which a disturbance exists is defined as in the following equation (Equation 22).

  It is assumed that h (x, t) is a function including system uncertainty and nonlinearity.

  When constrained to a hyperplane, the following equation (Equation 23) holds.

When the equivalent control input U _eq is obtained from the above equation (Equation 23), the following equation (Equation 24) is obtained.

  If the sliding mode occurs, the following equation (Equation 25) is established by substituting the equivalent control input (Equation 24) into Equation (Equation 22).

Then, can be expressed in the matching condition of the disturbance h is present in the range space of the input matrix _{B e (h (x, t} ) ⊂Range (B e)) , then the following expression (Expression 26).

  By substituting equation (Equation 26) into equation (Equation 25), the following equation (Equation 27) holds and the term of λ disappears.

  In other words, as long as the sliding mode occurs, the influence of disturbance is eliminated.

Thus, the target correction unit 52, when a predetermined hunting condition is satisfied, processing moderation target value r ₂ of the intake pipe pressure by the sliding mode controller 51 refers to.

The hunting condition is a reference for detecting a situation in which a sudden disturbance may occur to cause hunting of the control input X and the control output Y. In the present embodiment, the following four conditions are defined as hunting conditions, and when it is determined that all four conditions are satisfied, the target value smoothing process is started.
1) The absolute value of h (or B _e λ) exceeds a predetermined threshold value 2) The engine speed tends to decrease 3) The required fuel injection amount tends to decrease 4) The accelerator pedal depression amount decreases As is apparent from the equation (Equation 22) in the trend, h is a computational value calculated by substituting the actual plant state quantity _Xe and the control input U calculated by the controller 51 into the plant model. the difference between the state quantity X _e obtained by differentiating the time (i.e., the unit of the difference time per variation) is. In the state quantity X _e = [x _e1 , x _e2 , x _e3 , x _e4 ] ^T , x _e1 is the time integral z ₁ of the deviation of the EGR rate (r ₁ −y ₁ ), and x _e2 is the deviation of the intake pipe pressure ( r ₂ −y ₂ ), the time integral z ₂ , x _e3 is the EGR rate y ₁ , and x _e4 is the intake pipe pressure y ₂ . Similarly, in the disturbance h = [h ₁ , h ₂ , h ₃ , h ₄ ] ^T , h ₄ is a disturbance related to the intake pipe pressure y ₂ . The h ₄ from the measured value of the intake pipe pressure y _2, equal to minus the calculated value of the intake pipe pressure y ₂ controller 51 is calculated by substituting the control input U, which is calculated on the plant model.

FIG. 5 shows the result of experimentally confirming the correlation between the change in the vehicle speed of the automobile equipped with the internal combustion engine 2 and the fluctuation in the intake pipe pressure. During the period displayed in FIG. 5, the operation units 45, 42, and 33 are not operated at all. Nevertheless, the intake pipe pressure y ₂ increases and decreases. In particular, at the end of acceleration, the intake pipe pressure y ₂ shows a sharp drop. The disturbance h ₄ also increases significantly at the end of this acceleration. It is considered that the sudden drop in the intake pipe pressure y ₂ is mainly caused by a decline in the work of the exhaust turbo.

FIG. 6 shows a pattern of hunting that occurs at the end of acceleration. When the acceleration ends, the engine speed and the fuel injection amount decrease, and the target value r ₂ of the intake pipe pressure also decreases accordingly. The controller 51 operates the operating unit 45,42,33 in order to follow the intake pipe pressure y ₂ to the target value r ₂ descending. However, due to the sudden disturbance that occurs at the same time, the intake pipe pressure y ₂ is far below the target value r ₂ and undershoots, and then turns into an overshoot that jumps greatly by reaction, and then repeats vertical movement. Hunting state. Then, the hunting of the intake pipe pressure y ₂ triggers the hunting of the EGR rate y ₁ that is cooperatively controlled, and the hunting of the openings u ₁ , u ₂ , u ₃ of the operation units 45, 42, 33. It breaks out.

In order to prevent the above such hunting of the target correction unit 52, in addition to moderation to the target value r ₂ process, delaying the descent of the target value r ₂ effectively. Smoothing process is carried out by taking for example the moving average of the target value r _2. If the original target value set based on the engine speed, the fuel injection amount, etc. is r _2i (subscript i represents the calculation cycle of the ECU 5), the original target value in the last n previous calculation cycles is assumed. From r _2i , the target value r ₂ ′ given to the controller 51 can be calculated according to the following equation (Equation 28).

An example in which the target value r ₂ is smoothed is shown in FIG. However, the target value r ₂ may be smoothed using a weighted average filter, a low-pass filter, or the like instead of such a simple moving average filter. Further, the intended purpose can be achieved by smoothing the deviation (r ₂ −y ₂ ) of the intake pipe pressure applied to the controller 51 instead of the target value r ₂ .

FIG. 8 shows a procedure example of processing executed by the control device of the present embodiment. The control device calculates a calculated value of the intake pipe pressure y ₂ obtained by substituting the control input U calculated by the controller 51 into the model of the plant (step S1), and this value is actually measured for the intake pipe pressure y ₂ . The disturbance h ₄ is obtained by subtraction from the value (step S2). Then, it is determined whether or not the absolute value of the disturbance h ₄ exceeds a predetermined threshold value (step S3).

If the absolute value of the disturbance h ₄ exceeds the threshold value, it is next determined whether or not the engine speed tends to decrease (step S4). In step S4, the engine speed decreases when Ne _i-1 −N e _i <0 holds in the relationship between the current engine speed Ne _i and the engine speed Ne _i-1 in the past calculation cycle. It is determined that there is a tendency.

If the engine speed tends to decrease, it is further determined whether or not the required fuel injection amount tends to decrease (step S5). In step S5, the fuel injection amount decreases when Q _i-1 -Q _i <0 holds in the relationship between the current fuel injection amount Q _i and the fuel injection amount Q _i-1 in the past calculation cycle. It is determined that there is a tendency.

If the fuel injection amount also tends to decrease, it is finally determined whether or not the accelerator pedal depression amount tends to decrease (step S6). In step S6, the accelerator depression amount decreases when accpf _i-1 -accpf _i <0 holds in the relationship between the current accelerator depression amount accpf _i and the accelerator depression amount accpf _i-1 in the past calculation cycle. It is determined that there is a tendency.

Through steps S1 to S6, the dawn of all hunting condition is satisfied, starts to execute the smoothing processing of the target value r ₂ of the intake pipe pressure. In the annealing process, the moving average r ₂ 'of the target value r _2i that should be originally calculated is calculated (step S7), and this r ₂ ' is given to the controller 51 as the target value of the intake pipe pressure, and the control input U is calculated. (Step S8). When a predetermined period has elapsed since the start of the annealing process (step S9), the annealing process is terminated and the original target value r ₂ is given to the controller 51.

Through steps S1 to S6, if the any of the hunting condition is not met, given not execute the smoothing processing of the target value r ₂ of the intake pipe pressure, i.e. the original target value r ₂ to the controller 51 Needless to say, continue (step S10).

According to this embodiment, it is one that implements the control to follow the control output y _1, y ₂ of the apparatus attached to the internal combustion engine 2 or its target value r _1, r _2, each control output y ₁ , Y ₂ and their target values r ₁ , r ₂ based on deviations (r ₁ −y ₁ ) and (r ₂ −y ₂ ), servos that repeatedly calculate control inputs u ₁ , u ₂ and u ₃ a controller 51, and the actual value of the state amount x _e4 plant associated with the control output r _2, the control input u _1, u _2, the state quantity u ₃ is calculated by substituting the plant model x _e4 The target value r ₂ or deviation of the control output referred to by the servo controller 51 when the hunting condition including at least the condition that the change amount h ₄ of the difference from the calculated value per unit time exceeds the predetermined threshold is satisfied. to and a target correction unit that processes (r ₂ -y ₂₎ moderation of For configuring the control apparatus characterized, it is possible to suppress the sudden disturbance by annealing process for upon perceive a variation of the control input to follow the variation of the target value _{r 2 u 1, u 2,} u 3. As a result, it is possible to prevent hunting caused when a sudden disturbance occurs.

In particular, in the control system for controlling the internal combustion engine 2 equipped with the turbocharger and including the intake pipe pressure (or intake air amount) as the control output y ₂ , the intake pipe is set in the intake pipe at one time after the end of acceleration. The target pressure value r ₂ is subjected to a smoothing process. That is, the intake pipe pressure can be suitably reduced and controlled without intentionally operating the operating portions 45, 42, and 33 by utilizing the fact that the supercharging pressure naturally decreases as a disturbance after the end of acceleration.

Storing in advance a map that defines the relationship between the index value relating to the current status of the internal combustion engine 2 or the device attached thereto and the target value r ₂ of the control output y ₂ , and searching the map using the index value as a key. wherein for controlling the output in which to know the target value r ₂ of y _2, the disturbance of the degree capable of absorbing the controller 51 can be controlled by setting the target value r ₂ corresponding to the index value through. Only for a sudden disturbance that cannot be absorbed, the target value r ₂ set according to the index value is subjected to a smoothing process, thereby suppressing hunting.

The index value includes the rotational speed and fuel injection amount (or required load) of the internal combustion engine 2, and both the rotational speed and the fuel injection amount of the internal combustion engine 2 tend to decrease under the hunting conditions. Therefore, the control of the intake pipe pressure y ₂ after the end of acceleration can be suitably performed.

  Since the hunting conditions include that the accelerator depression amount tends to decrease, it is possible to effectively cope with a decrease in vehicle speed and a decrease in engine speed due to a decrease in accelerator depression amount.

  The present invention is not limited to the embodiment described in detail above. First, the multi-input feedback control technique realized by the servo controller 51 is not limited to the sliding mode control. It does not prevent the adoption of techniques other than sliding mode control, such as optimal control, H∞ control, backstepping control, and the like.

The index value relating to the current state of the internal combustion engine or the auxiliary device is not limited to the engine speed and the fuel injection amount. It is naturally possible to set the target value r ₂ after referring to the external atmospheric pressure, the cooling water temperature, and the like as index values.

The contents of the hunting conditions are not limited to those in the above embodiment. Depending on the hunting conditions, it may be assumed that the target value r _{1 of} the EGR rate (or the deviation (r ₁ −y ₁ ) of the EGR rate) is subjected to an annealing process to suppress hunting.

  Further, the control input variables in the EGR control are not limited to the EGR valve opening, the variable nozzle turbo opening, and the throttle valve opening. The control output variable is not limited to the EGR rate (or EGR amount) and the intake pipe pressure (or intake amount). It is also possible to construct a tertiary system with four inputs and three outputs by adding new input variables and output variables. For example, when a passage that bypasses the supercharger (compressor) is present in the intake system, a valve provided on the passage may be operated. At this time, the pressure or flow rate in the bypass passage can be included in the control output variable, and the opening of the valve on the bypass passage can be included in the control input variable.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be used, for example, as a control controller for controlling the EGR rate of an internal combustion engine attached with a supercharger and an EGR device.

5 ... ECU (control device)
51 ... Adaptive sliding mode controller (servo controller)
52. Target correction unit

Claims (5)

The control for causing the control output related to the internal combustion engine or the device attached thereto to follow the target value is performed,
A servo controller that repeatedly calculates a control input based on a deviation between the control output and its target value;
The amount of change per unit time of the difference between the actual value of the state quantity of the plant related to the control output and the calculated value of the state quantity calculated by substituting the control input into the plant model is a predetermined threshold value. And a target correction unit for smoothing a target value or deviation of a control output referred to by the servo controller when a hunting condition including at least a condition of exceeding is satisfied. It controls an internal combustion engine equipped with a turbocharger,
The control device according to claim 1, wherein the control output includes an intake pipe pressure or an intake air amount. A map that defines a relationship between an index value related to the current status of the internal combustion engine or the device attached thereto and a target value of the control output is stored in advance, and the control output is obtained by searching the map using the index value as a key. The control device according to claim 2, wherein the target value is obtained. The index value includes the rotational speed of the internal combustion engine and the fuel injection amount,
The control device according to claim 3, wherein the hunting condition includes that both the rotational speed of the internal combustion engine and the fuel injection amount tend to decrease. The control device according to claim 2, 3 or 4, wherein the hunting condition includes that the accelerator depression amount tends to decrease.

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