JP2019190313A - Control device of supercharger and control method of supercharger - Google Patents

Abstract

To provide a control device of a supercharger which can make compatible both following performance and responsiveness, and a control method of the supercharger.SOLUTION: A control device for controlling a supercharger has: a prediction part for calculating a prediction value of supercharge pressure after the lapse of a prescribed period when setting a drive amount of an actuator to a first drive amount on the basis of a measurement value of the supercharge pressure; and a control part for driving the actuator by the first drive amount until the prediction value of the supercharge pressure reaches the vicinity of a target value of the supercharge pressure, and drives the actuator so that the measurement value of the supercharge pressure follows the target value of the supercharge pressure after the prediction value of the supercharge pressure reaches the vicinity of the target value of the supercharge pressure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine supercharger control apparatus and control method.

  The engine supercharger includes a turbine that is rotated by a driving force generated by exhaust gas discharged from a combustion chamber of the engine, and a compressor that rotates in conjunction with the turbine and compresses intake air supplied to the combustion chamber. The intake air compressed by the supercharger is supplied to the combustion chamber after the flow rate is adjusted by the throttle.

  Of the exhaust discharged from the combustion chamber of the engine, the flow rate of the exhaust used as a driving force for rotating the turbocharger turbine is adjusted by a waste gate valve (hereinafter referred to as “WGV”). Is done. The WGV is provided on the upstream side of the turbine in the exhaust passage, and adjusts the flow rate of the exhaust that drives the turbine by allowing a part of the exhaust from the combustion chamber to escape to the bypass passage. The opening degree of the WGV is controlled by an actuator.

  Engine superchargers are typically feedback controlled to compensate for the effects of disturbances. For example, Patent Document 1 describes a control device that feedback-controls the opening degree of the WGV so that the measured value of the supercharging pressure follows the target value of the supercharging pressure. In Patent Literature 1, the occurrence of supercharging pressure overshoot is suppressed by correcting the feedback amount in accordance with the acceleration of the engine.

Japanese Patent Laid-Open No. 6-17661

  However, in the engine supercharger, as described above, there are several stages such as WGV, turbine, and compressor from when the actuator is driven until the change in the supercharging pressure of the surge tank appears. A delay time of about 2 seconds occurs. In a turbocharger having such a delay time, even if the feedback control method disclosed in Patent Document 1 is used, the reciprocity between feedback control and response is still a problem.

  That is, if the gain of feedback control is increased in order to improve the responsiveness, the followability is reduced and the supercharging pressure is overshooted. As a result, a shock occurs in the vehicle and the driver's experience is deteriorated. On the other hand, if the gain of the feedback control is reduced in order to improve the follow-up performance, it takes time for the responsiveness to decrease and the supercharging pressure to converge. As a result, the driver steps on and returns to the accelerator without waiting for the acceleration delay time, so that the supercharging pressure hunts. Such overshoot and hunting of the supercharging pressure adversely affect the fuel consumption of the vehicle.

  Then, an object of this invention is to provide the control apparatus and supercharger control method of a supercharger which can make tracking property and responsiveness compatible.

  According to one aspect of the present invention, a turbine that rotates by a driving force by exhaust gas discharged from a combustion chamber of an engine, a compressor that rotates in conjunction with the turbine and compresses intake air supplied to the combustion chamber, and a compressor A supercharging pressure measuring device that measures the supercharging pressure in a surge tank of compressed intake air, and an actuator that adjusts the opening of a waste gate valve that allows part of the exhaust to escape to the bypass passage upstream of the turbine. A control device for controlling a supercharger, wherein a predicted value of a supercharging pressure after a predetermined period when the driving amount of an actuator is set to a first driving amount is calculated based on a measured value of the supercharging pressure Until the absolute value of the deviation between the target value of the supercharging pressure and the predicted value of the supercharging pressure is less than the first threshold, the actuator is driven with the first drive amount, and the absolute value of the deviation is After it becomes less than the threshold value, the control device of the supercharger and a control unit for driving the actuator so that the measured value of the supercharging pressure follows the target value of the supercharging pressure is provided.

  Further, according to another aspect of the present invention, a turbine that is rotated by a driving force by exhaust discharged from a combustion chamber of an engine, a compressor that rotates in conjunction with the turbine and compresses intake air supplied to the combustion chamber, A supercharging pressure measuring device that measures the supercharging pressure in the surge tank of the intake air compressed by the compressor, and an actuator that adjusts the opening degree of the waste gate valve that releases a part of the exhaust to the bypass passage on the upstream side of the turbine. A method for controlling a supercharger, comprising: calculating a predicted value of a supercharging pressure after a predetermined period when the driving amount of an actuator is set to a first driving amount based on a measured value of the supercharging pressure The actuator is driven with the first drive amount until the absolute value of the deviation between the step and the target value of the boost pressure and the predicted value of the boost pressure is less than the first threshold, and the absolute value of the deviation The after becomes less than the first threshold value, the control method of the supercharger and a control step of driving the actuator so that the measured value of the supercharging pressure follows the target value of the supercharging pressure is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of a supercharger and the control method of a supercharger which can make the tracking property and response of a supercharging pressure compatible are provided.

It is the figure which showed the control apparatus of the supercharger which concerns on 1st Embodiment with the supercharger of the engine. It is the figure which showed schematically the structure of the control apparatus of the supercharger which concerns on 1st Embodiment. It is a timing chart which shows the time change of the throttle opening of an engine concerning a 1st embodiment, compressor pressure, supercharging pressure, and the amount of actuator drive. It is a flowchart which shows the control method of the supercharger which concerns on 1st Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can change suitably. In addition, components having the same or corresponding functions in each drawing are denoted by the same reference numerals, and the description thereof may be omitted or simplified.

  The supercharger control device of the present invention includes a prediction unit and a control unit. The predicting unit converts the predicted value of the supercharging pressure after a predetermined period when the driving amount of the actuator is set to the first driving amount such that the waste gate valve is in a closed state to the measured value of the supercharging pressure. Calculate based on Further, the control unit drives the actuator with the first drive amount until the predicted value of the supercharging pressure reaches the vicinity of the target value of the supercharging pressure, and the predicted value reaches the vicinity of the target value of the supercharging pressure. After that, the actuator is driven so that the measured value of the supercharging pressure follows the target value of the supercharging pressure. This predicted value is calculated based on, for example, a transfer function that models the time response of the supercharging pressure when the drive amount of the actuator is changed.

  As a result, the feedforward control is performed so that the supercharging pressure of the supercharger converges to the target value based on the predicted value, so that the followability and the responsiveness of the supercharging pressure are compatible.

[First Embodiment]
FIG. 1 is a diagram showing a supercharger control device 4 according to a first embodiment together with an engine supercharger 2. The supercharger 2 includes a turbine 21, a compressor 22, a WGV 23, a supercharging pressure measuring device 25, and an actuator 26.

  The turbine 21 is provided on the exhaust passage 11 and is rotated by a driving force by the exhaust discharged from the combustion chamber 10 of the engine. The compressor 22 is provided on the intake passage 12, rotates in conjunction with the turbine 21, and compresses the intake air supplied to the combustion chamber 10.

  The intake air compressed by the compressor 22 is adjusted in flow rate by the throttle valve of the throttle 13, temporarily stored in the surge tank 14, and then supplied to the combustion chamber 10. The opening degree of the throttle valve of the throttle 13 is adjusted according to the degree to which the driver depresses the accelerator pedal.

  The supercharging pressure measuring instrument 25 measures the supercharging pressure of the intake air in the surge tank 14 and outputs the measured value to the control device 4 described later.

  The WGV 23 is provided on the upstream side of the turbine 21 in the exhaust passage 11 and allows part of the exhaust discharged from the combustion chamber 10 to escape to the bypass passage 24. Thereby, WGV23 adjusts the flow volume of the exhaust_gas | exhaustion utilized as a driving force which rotates the turbine 21 of the supercharger 2 among the exhaust_gas | exhaustion discharged | emitted from the combustion chamber 10. FIG.

  The actuator 26 adjusts the opening degree of the WGV 23. FIG. 1 shows a diaphragm actuator 26. The present invention is particularly effective when applied to the supercharger 2 including the diaphragm type actuator 26 in which the delay time of the supercharger 2 is increased. Therefore, although the following description assumes that the actuator 26 is a diaphragm type, this embodiment is not limited to this. The actuator 26 may be another pressure regulating type or an electric type. The actuator 26 of the present embodiment includes a diaphragm 261 (diaphragm) and a VSV 262 (vacuum switching valve).

  The diaphragm 261 divides the diaphragm chamber 260 into two parts, and is deformed according to the pressure supplied from the chamber 263 (Chamber) and displaced in the left-right direction in the figure. The diaphragm 261 is connected to the WGV 23 via a rod 264, and adjusts the opening degree of the WGV 23 in accordance with the displacement of the diaphragm 261 in the horizontal direction in the drawing.

  The VSV 262 is provided on a negative pressure passage 265 that bypasses the upstream side and the downstream side of the compressor 22, and controls the pressure in the chamber 263 by opening and closing the negative pressure passage 265. The VSV 262 is driven by a drive circuit (not shown). In the VSV 262, the ratio of the length of the open period and the closed period of the negative pressure passage 265 may be controlled according to the duty ratio of the duty signal output from the control device 4 described later, or according to the duty ratio of the duty signal. Thus, the opening degree of the negative pressure passage 265 may be controlled.

  For example, when the VSV 262 is driven at a duty ratio of 0% to close the negative pressure passage 265, the pressure in the chamber 263 is increased to a pressure downstream of the compressor 22 (hereinafter referred to as “compressor pressure”). As a result, when the pressure acting on the diaphragm 261 increases and exceeds the set pressure necessary for the rod 264 and the WGV 23 to move, the diaphragm 261 pushes the rod 264 to increase the opening of the WGV 23.

  On the other hand, when the VSV 262 is driven at a duty ratio of 100% to open the negative pressure passage 265, the pressure in the chamber 263 is reduced by the negative pressure upstream of the compressor 22. As a result, the pressure acting on the diaphragm 261 is reduced, and the diaphragm 261 pulls the rod 264 to lower the opening of the WGV 23.

  In the supercharger 2 including the diaphragm type actuator 26 as shown in FIG. 1, a large number of stages are required from when the actuator 26 is driven to when the supercharging pressure of the surge tank 14 changes. Delay time occurs. The time response of the supercharging pressure in the surge tank 14 when the driving amount of the actuator 26 is changed is modeled by a transfer function. Hereinafter, a transfer function when the actuator 26 is a diaphragm type will be described.

The time change of the driving amount of the actuator 26 is D _vsv (t), and the Laplace conversion is D _vsv (s). Also, _let N _tbn (t) be the time change in the rotational speed of the turbine 21, and let _Latplace conversion be N _tbn (s). Here, the driving amount of the actuator 26 is a duty ratio by which the VSV 262 is driven when the actuator 26 is a diaphragm type. At this time, the time response of the rotational speed of the turbine 21 when the drive amount of the actuator 26 is changed is modeled by a first-order lag transfer function expressed by the following equation (1).
N _tbn (s) / D _vsv (s) = K ₁ / (1 + T ₁ · s) (1)

Further, the time change of the compressor pressure is P _cmp (t), and its Laplace transform is P _cmp (s). At this time, the time response of the compressor pressure when the rotation speed of the turbine 21 is changed is modeled by a first-order lag transfer function expressed by the following equation (2).
P _cmp (s) / N _tbn (s) = K ₂ / (1 + T ₂ · s) (2)

Further, the time change of the supercharging pressure of the surge tank 14 is _defined as P _bst (t), and the Laplace conversion is _defined as P _bst (s). At this time, the time response of the supercharging pressure when the compressor pressure changes is modeled by a phase delay transfer function expressed by the following equation (3).
P _bst / P _cmp (s) = exp (−T ₃ · s) (3)

From the above equations (1) to (3), the time response of the supercharging pressure when the drive amount of the actuator 26 is changed is modeled by a second-order lag transfer function represented by the following equation (4).
P _bst / D _vsv (s)
= K ₁ · K ₂ · exp (-T ₃ · s) / {(1 + T ₁ · s) (1 + T ₂ · s)} (4)

In the transfer function of the above equation (4), the delay time from when the drive amount of the actuator 26 is changed to when the change in the supercharging pressure of the surge tank 14 appears is substantially determined by the time constant T ₃ .

  FIG. 2 is a diagram schematically showing the configuration of the supercharger control device 4 according to the first embodiment. The control device 4 includes a calculation unit 40, a storage unit 41, an input unit 42, and an output unit 43.

The storage unit 41 stores a program for control and calculation executed by the calculation unit 40. Further, the storage unit 41 stores the transfer function of the above equation (4) together with time constants T ₁ , T ₂ , T ₃ . The storage unit 41 can include a semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), and an EPROM (Erasable Programmable ROM).

  The input unit 42 includes an interface circuit for receiving signals such as a measured value of the boost pressure output from the boost pressure measuring instrument 25 and a throttle opening degree output from the throttle 13. The output unit 43 has an interface circuit for outputting a duty signal to the VSV 262 of the actuator 26.

  The calculation unit 40 is a processor or an integrated circuit. The calculation unit 40 includes a control unit 44, a prediction unit 45, and a correction unit 46.

The control unit 44 feed-forward-controls the supercharger 2 until the predicted value of the supercharging pressure after a predetermined period reaches the vicinity of the target value of the supercharging pressure, and the predicted value of the supercharging pressure is the supercharging pressure. After reaching the vicinity of the target value, the supercharger 2 is feedback-controlled. The prediction unit 45 calculates the predicted value based on the drive amount of the actuator 26 and the measured value of the supercharging pressure. The correction unit 46 corrects the time constant T ₃ of the phase delay of the transfer function of the above equation (4) based on the time from when the driving amount of the actuator 26 is changed until the measured value of the boost pressure starts to decrease. To do. The operations of the control unit 44, the prediction unit 45, and the correction unit 46 will be described in detail later with reference to FIGS.

  FIG. 3 is a timing chart showing temporal changes in the throttle opening, the compressor pressure, the supercharging pressure, and the drive amount of the actuator 26 of the engine according to the first embodiment. 3A to 3D show the throttle opening of the throttle 13, the driving amount of the actuator 26, the compressor pressure, and the supercharging pressure, respectively, in order from the top. The horizontal axis of Fig.3 (a)-FIG.3 (d) has shown time. FIG. 4 is a flowchart showing a method for controlling the supercharger 2 according to the first embodiment. Hereinafter, the control method of the supercharger 2 by the control device 4 of the present embodiment will be described with reference to FIGS. 3 and 4.

When the driver of the vehicle depresses the accelerator pedal, at time t ₁ shown in FIG. 3, the throttle opening of the throttle 13 starts to rise. The control unit 44 sets a target value P ₀ of the supercharging pressure according to the throttle opening (step S1). The correspondence between the throttle opening and the target value P ₀ of the supercharging pressure is defined in a table stored in advance in the storage unit 41, for example. Therefore, the control unit 44 may set the target value P ₀ of the supercharging pressure with reference to the table.

At time t ₂ , when the throttle opening is equal to or greater than the threshold value W _th and the pressure acting on the diaphragm 261 is equal to or greater than the set pressure, the WGV 23 can be controlled. 1 is set to the drive amount D ₁ (step S2). Here, the first drive amount D ₁ is typically a drive amount of the actuator 26 such that the WGV 23 is in a closed state, and for example, the VSV 262 is driven with a duty ratio of 100%. As the value of the first drive amount D ₁ is larger, the responsiveness of the supercharger 2 is improved. However, the first drive amount D ₁ is not limited to a duty ratio of 100%. For example, when the target value P _{0 of the} supercharging pressure is small in the first place and the supercharging pressure exceeds the target value P ₀ when the WGV 23 is closed, the first drive amount D ₁ is, for example, the duty The ratio may be 90% or the duty ratio may be 80%.

At time t ₃ , the prediction unit 45 calculates the predicted value of the boost pressure after the predetermined period T _{0, the} measured value of the boost pressure measured by the boost pressure measuring device 25, and the first drive amount D of the actuator 26. Calculation based on ₁ (step S3). The prediction unit 45 calculates a predicted value of the supercharging pressure for each control cycle of the control device 4. Time t ₃ when shown in Fig. 3 illustrates as a representative one time control cycle.

Here, it is preferable that the length of the predetermined period T ₀ is approximately the same as the time constant T ₃ of the phase delay of the transfer function of the above equation (4). The time constant T ₃ of the transfer function represents a time response delay of the supercharger 2. Therefore, by setting the length of the predetermined period T ₀ to be approximately the same as the time constant T ₃ , the prediction unit 45 can be controlled by changing the drive amount of the actuator 26 in the nearest future. Can be predicted.

In the present embodiment, the predicting unit 45 calculates the predicted value of the supercharging pressure based on two types of predicted values, a first predicted value based on a transfer function and a second predicted value based on linear prediction. First, a method for calculating the first predicted value of the supercharging pressure will be described. The prediction unit 45 inputs the measured value of the supercharging pressure and the first drive amount D ₁ of the actuator 26 to the transfer function of the above equation (4), and calculates the first predicted value. The transfer function of the above equation (4) is stored in the storage unit 41 in advance. The first predicted value of the supercharging pressure is calculated as follows, for example.

When the above equation (1) is transformed, the following equation (5) is obtained.
s · N _tbn (s) = {K ₁ · D _vsv (s) −N _tbn (s)} / T ₁ (5)

When the above equation (5) is subjected to inverse Laplace transform, a differential equation of the following equation (6) is obtained.
dN _tbn (t) / dt = {K ₁ · D _vsv (t) −N _tbn (t)} / T ₁ (6)

When the differential equation of the above equation (6) is developed into a discrete system, the following equation (7) is obtained.
N _tbn (t + Δt)
= N _tbn (t) + {K ₁ · D _vsv (t) −N _tbn (t)} Δt / T ₁ (7)

The above equation (7), entering the N _tbn at time t ₀ (t ₀₎ and _{D vsv (t 0), N} tbn at time _{t 0 + Δt (t 0 +} Δt) is obtained. If this calculation is further repeated, N _tbn (t) at an arbitrary future time t is obtained. It is also possible to algebraically calculate N _tbn (t) at an arbitrary future time t by _obtaining a general solution of the differential equation of the above equation (6).

Similarly, when the above equation (2) is subjected to inverse Laplace transform and developed into a discrete system, the following equation (8) is obtained.
P _cmp (t + Δt)
= P _cmp (t) + {K ₂ · N _tbn (t) −P _cmp (t)} Δt / T ₂ (8)

Similarly, when the above equation (3) is subjected to inverse Laplace transform and developed into a discrete system, the following equation (9) is obtained.
P _bst (t) = P _cmp (t−T ₃ ) (9)

The above equation (9) represents that the waveform of the time change of the supercharging pressure is delayed by the time constant T _{3 with} respect to the waveform of the time change of the compressor pressure. For example, the time change waveform 400 of the measured value of the boost pressure shown in FIG. 3D is a time constant T with respect to the time change waveform 401 of the measured value of the compressor pressure shown in FIG. Delayed by ₃ .

The prediction unit 45 sequentially calculates the rotational speed N _tbn (t), the compressor pressure P _cmp (t), and the supercharging pressure P _bst (t) of the turbine 21 according to the above equations (7) to (9). Then, the boost pressure P _bst (t ₃ + T ₀ ) after the predetermined period T ₀ is calculated as the first predicted value. FIG. 3D shows a waveform 402 of the temporal change of the first predicted value of the boost pressure calculated in this way. The first predicted value is preferably recalculated every time the measured value of the supercharging pressure is acquired. However, in order to suppress the calculation amount of the control device 4, for example, the first predicted value was calculated at the timing of the past time t ₂ . The waveform 402 of the first predicted value may be used at the subsequent time t ₃ .

Next, a method for calculating the second predicted value of the supercharging pressure will be described. The prediction unit 45 calculates the second predicted value on the assumption that the measured value of the supercharging pressure changes with time approximately linearly. For example, the prediction unit 45 calculates the second predicted value of the supercharging pressure after the predetermined period T ₀ from the measured values of the supercharging pressure at a plurality of past times by linear prediction of the following equation (10). Here, the coefficient a ₁ is typically 1 and is adjusted as necessary. FIG. 3D shows a waveform 403 of the temporal change of the second predicted value of the boost pressure calculated in this way.
P _bst (t ₃ + T ₀ ) = P _bst (t ₃ )
+ A ₁ · {dP _bst (t ₃ ) / dt} · T ₀ (10)

Each of the first predicted value and the second predicted value has an advantage. The transfer function of the above equation (4) on which the first predicted value depends depends on the time response of the supercharging pressure when the driving amount of the actuator 26 is changed by the parameters of the time constants T ₁ , T ₂ , T ₃ , etc. Modeled. Therefore, the first predicted value can accurately predict the future supercharging pressure that is farther than the time constant T ₃ that represents the delay time of the supercharging pressure time response. On the other hand, since the second predicted value is calculated by linear prediction based on the measured values of the boost pressure at a plurality of past times, it is possible to accurately predict the future boost pressure closer to the time constant T _3. it can.

Therefore, the prediction unit 45 uses the weighted average of the first predicted value and the second predicted value as the final predicted value of the supercharging pressure, as shown in the following equation (11). As a result, it is possible to accurately predict the predicted value of the supercharging pressure after a predetermined period T _{0 that is} approximately equal to the time constant T ₃ . Here, the weighting factors b ₁ and b ₂ are positive real numbers that satisfy b ₁ + b ₂ = 1, and are adjusted according to the length of the predetermined period T ₀ .
Prediction value = b ₁ · 1st prediction value + b ₂ · 2nd prediction value (11)

For example, when predicting the supercharging pressure after a predetermined period T ₀ far from the time constant T ₃ , the predicting unit 45 sets the weighting factor b ₁ to be larger than the weighting factor b ₂ and exceeds the time constant T _3. When predicting the supercharging pressure after a close predetermined period T ₀ , the weighting factor b ₂ is set larger than the weighting factor b ₁ . Note that the prediction unit 45 calculates a final predicted value based on only one of the first predicted value and the second predicted value, with one of the weighting factors b ₁ and b ₂ being 1 and the other being 0. Also good.

  Next, the control unit 44 determines whether or not the distortion of the waveform 400 of the measured value of the supercharging pressure is large (step S4). The prediction accuracy of the first predicted value and the second predicted value decreases when the waveform 400 of the time change of the measured value of the boost pressure is greatly distorted. Therefore, the control unit 44 determines whether or not the waveform 400 of the temporal change in the measured value of the supercharging pressure is approximately linear so that the control is not performed based on the predicted value with reduced accuracy.

Based on the measured values of the boost pressure at a plurality of past times, the control unit 44 converts the waveform 400 of the measured value of the boost pressure to the second-order differential term as shown in the following equation (12), for example. Interpolate with the expanded Taylor series. Then, when the absolute value of the second-order differential component of the obtained waveform 400 is greater than or equal to the second threshold value, it is determined that the distortion of the waveform 400 is large. Here, the coefficients a ₁ and a ₂ are typically 1, and are adjusted as necessary.
P _bst (t + Δt) = P _bst (t)
+ A ₁ · {dP _bst (t) / dt} · Δt
+ A ₂ · {d ² P _bst (t) / dt ² } · (Δt) ² (12)

  When the control unit 44 determines that the distortion of the waveform 400 of the measured value of the boost pressure is large (“Yes” in step S4), the control unit 44 accurately predicts the measured value of the boost pressure. Is determined to be difficult, and the process proceeds to step S7. On the other hand, when it is determined that the distortion of the waveform 400 of the measured value of the supercharging pressure is small (“No” in step S4), the control unit 44 advances the processing to the next step S5. This prevents the control from being performed based on the predicted value with reduced accuracy.

Next, the control unit 44 determines whether or not the predicted value of the supercharging pressure greatly exceeds the target value P ₀ of the supercharging pressure (step S5). For example, when the deviation obtained by subtracting the target value P ₀ of the boost pressure from the predicted value of the boost pressure exceeds the third threshold Th ₃ , the control unit 44 determines that the predicted value of the boost pressure is the boost pressure. It determines that greatly exceeds the target value P ₀ of the. At time t ₃ , the predicted value of the supercharging pressure does not exceed the target value P ₀ of the supercharging pressure (“No” in step S5), and the control unit 44 advances the processing to the next step S6. On the other hand, when the predicted value of the supercharging pressure greatly exceeds the target value P ₀ of the supercharging pressure (“Yes” in step S5), the control unit 44 has failed in the feedforward control using the predicted value. And the process proceeds to step S7. As a result, when the feedforward control fails, the feedforward control can be immediately terminated to suppress the occurrence of overshoot of the supercharging pressure.

Next, the control unit 44 determines whether or not the predicted value of the supercharging pressure has reached the vicinity of the target value P ₀ of the supercharging pressure (step S6). Here, the vicinity of the target value P _0, 2 × first supercharging pressure is centered on the target value P ₀ which can be regarded as being substantially converged to the target value P ₀ is after ₀ least a predetermined time period T It refers to the range of boost pressure threshold Th _1. This first threshold value Th ₁ is a value smaller than the third threshold value Th ₃ used in the determination in the previous step S5. For example, the control unit 44 determines whether or not the absolute value of the deviation between the target value P _{0 of the} boost pressure and the predicted value is less than the first threshold Th ₁ , and the predicted value of the boost pressure is the boost pressure. It is determined whether the vicinity of the target value P ₀ is reached. The control unit 44 repeats steps S3 to S6 until the predicted value of the boost pressure reaches the vicinity of the target value P ₀ of the boost pressure.

When the predicted value of the supercharging pressure reaches the vicinity of the target value P ₀ of the supercharging pressure at time t ₄ , the control unit 44 determines that the feedforward control using the predicted value is successful.

Next, the control unit 44 or the correction unit 46 sets the drive amount of the actuator 26 to the second drive amount D ₂ corresponding to the target value P ₀ of the supercharging pressure (step S7). Here, the second drive amount D ₂ is a drive amount smaller than the first drive amount D _1. If the actuator 26 is continuously driven with the second drive amount D ₂ , the supercharging pressure will eventually reach the target value. The driving amount of the actuator 26 converges to P ₀ . The correspondence relationship between the target value P _{0 of the} supercharging pressure and the second drive amount D ₂ of the actuator 26 is defined in, for example, a table stored in advance in the storage unit 41. Accordingly, the correction unit 46, a second drive amount D _2, may be set by referring to the table.

At time t ₅ , the correction unit 46 measures a delay time (t ₅ −t ₄ ) from when the drive amount of the actuator 26 is set to the second drive amount D ₂ until the boost pressure starts to decrease (step ₅ ). S8). The time t ₅ when the supercharging pressure has started to decrease is obtained, for example, as the time t ₅ corresponding to the maximum value of the waveform 400 of the time change of the measured value of the supercharging pressure.

Next, the correcting unit 46 corrects the time constant T ₃ of the phase delay of the transfer function based on the measured delay time (t ₅ -t ₄ ) (step S9). The delay time (t ₅ -t ₄ ) is proportional to the time constant T ₃ of the transfer function. Therefore, by measuring the proportional constant β in advance, the time constant T ₃ is corrected according to the following equation (13). Thereby, the accuracy of the first predicted value is further improved. At this time, the time constant T ₃ may be corrected by an average value of delay times (t ₅ −t ₄ ) measured a plurality of times.
Time constant T ₃ = β × delay time (t ₅ −t ₄ ) (13)

Next, the control unit 44 performs feedback control of the actuator 26 so that the measured value of the supercharging pressure follows the target value P ₀ of the supercharging pressure (step S10).

  As described above, the prediction unit of the supercharger control device according to the present embodiment calculates the predicted value of the supercharging pressure after a predetermined period when the driving amount of the actuator is set to the first driving amount as the supercharging pressure. Calculate based on measured values. The control unit drives the actuator with the first drive amount until the absolute value of the deviation between the target value of the boost pressure and the predicted value of the boost pressure is less than the first threshold, and the absolute value of the deviation is the first value. After being less than one threshold, the actuator is driven so that the measured value of the supercharging pressure follows the target value of the supercharging pressure.

  As a result, the feedforward control is performed so that the supercharging pressure of the supercharger converges to the target value based on the predicted value, so that the followability and the responsiveness of the supercharging pressure are compatible.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

2 Supercharger 4 Controller 10 Combustion chamber 11 Exhaust passage 12 Intake passage 13 Throttle 14 Surge tank 21 Turbine 22 Compressor 23 WGV (Waste gate valve)
DESCRIPTION OF SYMBOLS 24 Bypass passage 25 Supercharging pressure measuring device 26 Actuator 41 Memory | storage part 42 Input part 43 Output part 44 Control part 45 Prediction part 46 Correction | amendment part 260 Diaphragm chamber 261 Diaphragm 262 VSV (Vacuum Switching Valve)
263 Chamber 264 Rod 265 Negative pressure passage

Claims (10)

A turbine that is rotated by driving force generated by exhaust discharged from the combustion chamber of the engine;
A compressor that rotates in conjunction with the turbine and compresses the intake air supplied to the combustion chamber;
A supercharging pressure measuring device for measuring a supercharging pressure in a surge tank of intake air compressed by the compressor;
An actuator for adjusting the opening degree of a waste gate valve for allowing a part of the exhaust to escape to the bypass passage on the upstream side of the turbine;
A control device for controlling a turbocharger comprising:
A prediction unit that calculates a predicted value of the supercharging pressure after a predetermined period when the driving amount of the actuator is set to the first driving amount, based on the measured value of the supercharging pressure;
The actuator is driven with the first driving amount until the absolute value of the deviation between the target value of the supercharging pressure and the predicted value of the supercharging pressure is less than a first threshold, and the absolute value of the deviation is the first value. A control unit that drives the actuator so that the measured value of the supercharging pressure follows the target value of the supercharging pressure after being less than one threshold;
A supercharger control device. A storage unit that stores a transfer function that models a time response of the supercharging pressure when the drive amount of the actuator is changed;
The prediction unit calculates, as the first prediction value, the supercharging pressure after the predetermined period obtained by inputting the drive amount of the actuator and the measured value of the supercharging pressure to the transfer function. Calculating a predicted value of the supercharging pressure based on the value;
The supercharger control device according to claim 1. The predetermined period is a time constant of the phase delay of the transfer function.
The supercharger control device according to claim 2. When the absolute value of the deviation is less than the first threshold, the drive amount of the actuator is set to a second drive amount that is smaller than the first drive amount and corresponds to the target value of the supercharging pressure. And then a correction unit that corrects the time constant of the phase delay of the transfer function based on the time until the measured value of the supercharging pressure starts to decrease,
The supercharger control device according to claim 3. The prediction unit calculates the boost pressure after the predetermined period as a second predicted value by linear prediction based on the measured values of the boost pressure measured at a plurality of past times.
The prediction unit uses a weighted average of the first predicted value and the second predicted value as a predicted value of the supercharging pressure.
The control device according to any one of claims 2 to 4. The control unit obtains a time-change waveform of the measured value of the boost pressure based on the measured value of the boost pressure measured at a plurality of past times, and the absolute value of the second-order differential component of the waveform is If the second threshold value or more, the drive amount of the actuator is set to a second drive amount that is smaller than the first drive amount and that corresponds to the target value of the supercharging pressure;
The control device according to any one of claims 1 to 3. The control unit sets the drive amount of the actuator to the second drive amount when a deviation obtained by subtracting the target value of the boost pressure from the predicted value of the boost pressure exceeds a third threshold value. ,
The control device according to claim 6. The first drive amount is a drive amount of the actuator that causes the waste gate valve to be closed.
The control device according to any one of claims 1 to 7. The actuator has a VSV that controls a pressure acting on a diaphragm interlocked with the waste gate valve by opening and closing a passage that bypasses the upstream side and the downstream side of the compressor,
The control device according to any one of claims 1 to 8, wherein the control unit controls the VSV to adjust an opening degree of the waste gate valve. A turbine that is rotated by driving force generated by exhaust discharged from the combustion chamber of the engine;
A compressor that rotates in conjunction with the turbine and compresses the intake air supplied to the combustion chamber;
A supercharging pressure measuring device for measuring a supercharging pressure in a surge tank of intake air compressed by the compressor;
An actuator for adjusting the opening degree of a waste gate valve for allowing a part of the exhaust to escape to the bypass passage on the upstream side of the turbine;
A method of controlling a turbocharger comprising:
A prediction step of calculating a predicted value of the supercharging pressure after a predetermined period when the driving amount of the actuator is set to the first driving amount based on the measured value of the supercharging pressure;
The actuator is driven with the first driving amount until the absolute value of the deviation between the target value of the supercharging pressure and the predicted value of the supercharging pressure is less than a first threshold, and the absolute value of the deviation is the first value. A control step of driving the actuator so that the measured value of the supercharging pressure follows the target value of the supercharging pressure after being less than one threshold;
A method for controlling a supercharger.

Images