JP3738604B2 - Control method of turbocharged engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The turbocharger is provided with a supercharging pressure sensor in an intake passage, and inputs the supercharging pressure measured by the supercharging pressure sensor and controls the supercharging pressure by the opening degree of a wastegate provided in the turbocharger. The present invention relates to a method for controlling an engine with a charger.
[0002]
More specifically, the present invention relates to a turbocharger engine control method capable of diagnosing a supercharging pressure control component and stopping supercharging pressure control at the time of failure.
[0003]
[Prior art]
In an engine equipped with a turbocharger such as a passenger car, bus or truck, the turbine 11t on the exhaust passage 3 side is driven by the exhaust gas discharged from the engine E, and this rotation is coaxial with the turbine 11t as shown in FIG. The compressor 11c on the intake passage 2 side connected to is rotated to pressurize the intake air to supercharge the intake air.
[0004]
In this turbocharger 11, the supercharging pressure Pb exceeds a preset maximum supercharging pressure in order to prevent the cylinder E and the like from being damaged due to excessive supercharging when the engine E is at a high speed. In this case, a waste gate 30 is provided for adjusting the supercharging pressure Pb by bypassing a part of the exhaust gas from the turbine 11t.
[0005]
Further, the boost pressure Pb is controlled by adjusting the opening degree of the wastegate 30, and for example, the operation state of the engine E is judged from the target fuel injection amount and the engine rotational speed Ne, and this operation is performed. The supercharging pressure Pb is optimal for the state.
[0006]
That is, a supercharging pressure (intake pressure) sensor 21 is provided in the intake passage 2, and the actual supercharging pressure (intake pressure) is detected by the supercharging pressure sensor 21, and the actual supercharging pressure approaches the target supercharging pressure. As described above, so-called feedback control is performed in which control is performed in accordance with the deviation between the measured supercharging pressure and the target supercharging pressure. By this feedback control, the actual supercharging pressure can be made closer to the target supercharging pressure that is the control target.
[0007]
For adjusting the opening degree of the wastegate 30, a negative pressure chamber of a diaphragm to which the wastegate valve 30b is connected and a vacuum pump 34 are connected by an air pipe 32, and an electromagnetic variable adjustment that is controlled to be opened and closed by the controller 13 A valve (EVRV) 33 is provided.
[0008]
Then, the opening degree of the wastegate 30 is adjusted by sending a control signal of a predetermined duty ratio from the controller 13 to the electromagnetic variable adjustment valve 33, and adjusting the pressure in the negative pressure chamber of the diaphragm. The waste gate valve 30b is lifted and the waste gate 30 is opened so that the internal pressure of the negative pressure chamber of the diaphragm communicating with the vacuum pump 34 decreases.
[0009]
[Problems to be solved by the invention]
By the way, the above feedback control of the supercharging pressure is possible when the wastegate is normally opened and closed. That is, it is premised that supercharging pressure control parts such as an actuator, a solenoid valve, and a vacuum pump for controlling and driving the wastegate operate normally without failure.
[0010]
These supercharging pressure control parts may cause failures such as deterioration of the vacuum pump parts and poor wiring from the controller to the solenoid valve. If it occurs during the supply pressure control operation, the feedback control of the supercharging pressure is not performed normally, and the supercharging pressure becomes excessive or excessive. In particular, when the supercharging pressure becomes excessive, abnormal combustion occurs and the in-cylinder pressure rises beyond the limit, which may cause damage to parts around the combustion chamber.
[0011]
For this reason, in a turbocharged engine performing prior art supercharging pressure control, the deviation between the measured supercharging pressure and the target supercharging pressure is determined to be a predetermined value by detecting the failure state of this supercharging pressure control component. If it continues for more than a certain period of time, a failure is determined.
[0012]
However, when this wastegate valve fails near the middle position of the opening, the deviation between the measured supercharging pressure and the target supercharging pressure does not exceed a predetermined value. There is a problem that the supercharging pressure control is continued in this fault state.
[0013]
In addition, when the supercharging pressure becomes excessive, if the fuel injection amount is increased, the in-cylinder pressure rises, and there is a problem that damage occurs around the combustion chamber.
[0014]
The present invention has been made to solve the above-described problems, and its purpose is to determine a working state of a supercharging pressure control component during operation of an engine with a turbocharger that performs supercharging pressure control, and to perform a normal state. If this is the case, feedback control is performed based on the measured boost pressure, and if it is abnormal, it is determined that the turbocharge pressure control component has failed, and the boost pressure control is stopped. It is an object of the present invention to provide a method for controlling a turbocharged engine capable of setting an upper limit on the fuel amount.
[0015]
[Means for Solving the Problems]
The turbocharged engine control method for achieving the above object is configured as follows.
1) In a turbocharged engine that includes a turbocharger and a supercharging pressure sensor, and that inputs a measured supercharging pressure detected by the supercharging pressure sensor and feedback-controls the supercharging pressure.
A correction amount for feedback control is calculated from the deviation between the measured supercharging pressure detected by the supercharging pressure sensor and the target supercharging pressure, and the correction amount and the deviation are compared with a predetermined determination value, respectively. Determine the failure of the supply pressure control parts,
When it is determined that the failure is normal, the boost pressure control is performed by feedback control using the correction amount,
When it is determined in the failure determination that there is a failure, the supercharging pressure control is not performed.
[0016]
2) More specifically, a turbocharger including a turbine provided in the exhaust passage and a compressor provided in the intake passage is provided, and a supercharging pressure sensor is provided in the intake passage, and the turbine provided in the turbocharger is bypassed. In the control method of the turbocharged engine that performs adjustment control of the opening degree of the wastegate by duty ratio control and controls the supercharging pressure,
A basic supercharging pressure and a basic duty ratio corresponding to the basic supercharging pressure are calculated from the target fuel injection amount and the engine speed, and the basic supercharging pressure is corrected to calculate a target supercharging pressure. The final duty ratio is obtained by adding a correction amount calculated according to the deviation between the measured supercharging pressure detected by the supercharging pressure sensor and the target supercharging pressure to the duty ratio, and based on the final duty ratio While feedback controlling the opening of the wastegate,
When the correction amount is a correction lower limit value or a correction upper limit value, and the deviation is not within a predetermined determination range, the boost pressure control component is determined to be faulty.
[0017]
That is, the target boost pressure calculated by correcting the basic boost pressure to the basic duty ratio, which is the operation amount obtained from the target fuel injection amount and the engine speed, and the measured boost pressure detected by the boost pressure sensor The final duty ratio is obtained by adding the correction of the duty ratio calculated from the deviation from the above, and the opening degree of the wastegate is feedback controlled based on the final duty ratio.
[0018]
At the same time, whether the correction of the duty ratio, which is the feedback correction term, is the upper limit value (maximum 100%) or lower limit value (minimum 0%) of the duty ratio control Use as one of the conditions.
3) In this failure determination, when the correction amount is a correction upper limit value and the deviation is larger than a predetermined determination range upper limit value, a boost pressure control component is provided on the fully closed side of the wastegate. Is determined to be malfunctioning,
When the correction amount is a correction lower limit value and the deviation is smaller than a predetermined determination range lower limit value, it is determined that the supercharging pressure control component has failed on the fully open side of the wastegate.
4) Furthermore, when it is determined that the supercharging pressure control component has failed on the fully closed side of the wastegate, an upper limit is set for the target fuel injection amount.
[0019]
According to the above configuration, not only the determination of the magnitude of the deviation between the measured supercharging pressure detected by the supercharging pressure sensor and the target supercharging pressure, but also a correction that is a feedback correction term for control calculated from this deviation. Since the failure determination of the boost pressure control component is performed in combination with the determination of the minute value, the failure determination is more accurate.
[0020]
In other words, by adding this correction amount determination, even if the deviation between the measured supercharging pressure and the target supercharging pressure is not large, the state where the correction amount is inclined to one of the open side and the closed side continues for a predetermined time. In addition, it is possible to detect a state where the supercharging pressure control is not normally performed.
[0021]
Further, it is detected whether the waste of the wastegate is open or closed, and the fuel injection amount is determined only when it is determined that the wastegate has failed on the closed side where the supercharging pressure is excessive. Therefore, even if the supercharging pressure becomes excessive due to a failure, the increase in the in-cylinder pressure is suppressed by limiting the fuel injection amount, so that damage around the combustion chamber is avoided.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
〔overall structure〕
The engine E shown in FIG. 6 is an engine E in which a turbocharger 11 provided with a turbine 11t in the exhaust passage 3 and a compressor 11c in the intake passage 2 is disposed. The turbocharge 11 has a wastegate 30 that bypasses the turbine 11t. The supercharging pressure Pb is controlled by the opening degree of the wastegate 30.
[0023]
Further, a supercharging pressure sensor 21, a mass air flow sensor (intake air amount sensor) 22, and an intake air temperature sensor 23 are provided in the intake passage 2, and the measured supercharging pressure Pbm detected by these sensors 21, 22, 23, A controller (ECM) 13 is provided for controlling the overall engine operation by inputting the air amount Vb, the intake air temperature Tb, the engine rotational speed Ne detected by a rotational speed sensor (not shown), and the like.
[0024]
The opening of the wastegate 30 is adjusted by connecting the wastegate valve 30b to the diaphragm in the actuator of the wastegate 30, and the negative pressure chamber 30a of the diaphragm is connected to the electromagnetic valve (EVRV: Electric Variable Variable) by the air pipe 32. It is configured to be connected to the vacuum pump 34 via a regulation valve (electromagnetic variable adjustment valve) 33.
[0025]
The opening / closing of the electromagnetic valve 33 is controlled by a predetermined duty signal (pulse drive signal) output from the controller 13, and the pressure in the negative pressure chamber 30a is adjusted by the opening / closing amount to reduce the internal pressure in the negative pressure chamber 30a. Thus, the valve 30b for opening and closing the bypass passage 30c of the wastegate 30 is lifted to increase the opening degree.
[0026]
The vacuum pump 34 is also used for opening / closing control of the EGR valve 14 provided in the EGR passage 3. An electromagnetic valve 15 and an air pipe 16 are provided for opening and closing the EGR valve 14.
[Supercharging pressure control]
The supercharging pressure control according to the present invention has the supercharging pressure control flow of FIG. 1, the failure diagnosis flow of the supercharging pressure control component of FIG. 2, and the fuel injection amount control flow of FIG. The controller (ECM) 13 that controls the overall operation of the engine is configured as part of the engine operation control. 4 and 5 are block diagrams corresponding to the supercharging pressure control flow of FIG. 2 and the fuel injection amount control flow of FIG. 3, respectively.
[0027]
In addition, these flows are only examples, and it is possible to perform control according to the present invention in different flows, and the present invention is not limited to these flows. In addition, the detection data such as the measured supercharging pressure is averaged for noise removal, etc., but these work parts are excluded in the flow of FIG. 1 to make the control flow easy to understand. It is shown.
[0028]
The supercharging pressure control flow in FIG. 1, the failure diagnosis flow for the supercharging pressure control component in FIG. 2, and the fuel injection amount control flow in FIG. 3 are derived from the main control flow for controlling the overall engine operation. It is called repeatedly as necessary, and is executed as follows.
[Supercharging pressure control flow]
First, the supercharging pressure control flow for performing the feedback control shown in FIGS. 1 and 4 will be described.
[0029]
In this supercharging pressure control flow, the wastegate valve 30b that controls the opening and closing of the wastegate 30, the diaphragm, the negative pressure chamber 30a of the diaphragm, the air pipe 32, the solenoid valve 33, the vacuum pump 34, and other parts for supercharging pressure control are broken. If there is, the supercharging pressure control is stopped, and if the supercharging pressure control component is normal, PI control feedback control is performed, and if the control deviation ΔPmt is outside the predetermined control range ΔPki to ΔPko, The correction amounts ΔCcp and ΔCci in the feedback control are the same as in the previous control.
[0030]
That is, when the supercharging pressure control component is normal, the supercharging pressure Pb is a control amount, the target supercharging pressure Pbt is a target value, and the final duty ratio, which is a pulse drive signal for duty ratio control, is used as an operation signal. The feedback control is performed with the control element as the control element, and the supercharging pressure control is stopped when the supercharging pressure control component fails.
[0031]
First, when this supercharging pressure control flow is called and started, in step S10, various data such as the target fuel injection amount Qt, the engine speed Ne, the intake air temperature Tb, the atmospheric pressure Pa, and the failure flags Fu and Fd are input. In step S11, the basic supercharging pressure Pbb and the basic duty ratio DCbase are determined by referring to the three-dimensional map data Pbb (Qt, Ne) and DCbase (Qt, Ne) from the target fuel injection amount Qt and the engine speed Ne. calculate.
[0032]
Next, in step S12, the failure flags Fu and Fd calculated and output in the failure diagnosis flow of the supercharging pressure control component shown in FIG. 3 described later are checked.
[0033]
If either of the failure flags Fu and Fd is set to “1” and it is determined that the boost pressure control component for opening and closing the wastegate 30 has failed, the feedback control is not performed and step S24 is performed. In step S26, a supercharging pressure control stop command is output. In step S26, various data are output and the process returns.
[0034]
If both of the failure flags Fu and Fd are “0” and there is no failure, the process proceeds to step S13 and subsequent steps, and correction terms ΔCcp and ΔCci of the final duty ratio DCfnl are calculated to perform feedback control.
[0035]
First, in step S13, a measured boost pressure Pbm, a predetermined control inner determination value ΔPki, and a control outer determination value ΔPko are input from the boost pressure sensor 21. Correction by Tb and atmospheric pressure Pa is performed, that is, the basic supercharging pressure Pbb is multiplied by the correction coefficient Kt (Tb), and the correction coefficient Kp (Pa) is further added to calculate the target supercharging pressure Pbt. .
[0036]
Next, in step S15, a deviation ΔPmt (= Pbm−Pbt) between the measured supercharging pressure Pbm and the target supercharging pressure Pbt is calculated. In step S16, the absolute value of the deviation ΔPmt is determined to be a predetermined control inner determination value ΔPki and an outer control value. It is determined whether or not it is within a predetermined determination range between the determination values ΔPko.
[0037]
If the absolute value of the deviation ΔPmt is within a predetermined determination range ΔPki to ΔPko, the process proceeds to step S17 to calculate corrections ΔCcp and ΔCci corresponding to the deviation ΔPmt, and within the predetermined determination range ΔPki to ΔPko. If not, the process proceeds to step S20.
[0038]
In step S17, a P correction term ΔCcp for proportional correction of the deviation ΔPmt is obtained by multiplying the deviation ΔPmt by the correction coefficient Kp of the P correction term. In step S18, the I correction term ΔCci for integral correction of the deviation ΔPmt is multiplied by the correction coefficient Ki of the I correction term, and the previous I correction term ΔCcim is added.
[0039]
Next, in step S19, the final duty ratio DCfnl is calculated by adding the P correction term ΔCcp and the I correction term ΔCci to the basic duty ratio DCbase obtained in step S11.
[0040]
If it is determined in step S16 that the absolute value of the deviation ΔPmt is not within the predetermined control determination value (ΔPki to ΔPko) between the predetermined control inner determination value ΔPki and the predetermined control inner determination value ΔPko, The deviation ΔPmt is small and the measured supercharging pressure Pbm is close to the target supercharging pressure Pbt, and it is not necessary to newly calculate a correction amount, or the deviation ΔPmt is large and the measured supercharging pressure Pbm is far from the target supercharging pressure Pbt. However, since there is a possibility that it is transiently separated, the process proceeds to steps S20 and S21 without newly calculating the correction amounts ΔCcp and ΔCci, and uses the previous P correction term ΔCcpm and I correction term ΔCcim.
[0041]
In step S22, the basic duty ratio DCbase obtained in step S11 is added to the P correction term ΔCcp and I correction term ΔCci calculated in steps S20 and S21 to calculate the final duty ratio DCfnl.
[0042]
Next, in step S23, the P correction term ΔCcp and the I correction term ΔCci are stored in ΔCcpm and ΔCcim, and in step S25, the final duty ratio DCfnl for control is converted into a pulse drive signal. Feedback control of the supercharging pressure Pb is performed by adjusting the opening degree of the wastegate 30 by outputting to the valve (EVRV).
[0043]
The opening / closing relationship between the duty ratio and the wastegate 30 is controlled so that the wastegate 30 is fully closed when the duty ratio is 0%, and the wastegate 30 is fully opened when the duty ratio is 100%. Is done.
Then, various data such as a control deviation ΔPmt, a P correction term ΔCcp, and an I correction term ΔCci used in other flows are output.
[0044]
In this embodiment, correction according to the deviation ΔPmt between the measured supercharging pressure Pbm and the target supercharging pressure Pbt is performed by PI control, but only the P (proportional) term is used depending on the nature and necessity of the control. Alternatively, it may be performed only with the I (integration) term, or D (differentiation) correction may be additionally combined. That is, P, I, PI, PD, and PID control may be used.
[0045]
According to the above supercharging pressure control flow, the basic supercharging pressure Pbb and the basic duty ratio DCbase are calculated from the target fuel injection amount Qt and the engine rotational speed Ne, and the basic supercharging pressure Pbb is corrected to correct the target supercharging. The pressure Pbt is calculated, and the correction amount ΔCcpi (= ΔCcp + ΔCci) calculated according to the deviation ΔPmt between the measured boost pressure Pbm detected by the boost pressure sensor 21 and the target boost pressure Pbt is added to the basic duty ratio DCbase. Is added to obtain a final duty ratio DCfnl. Based on this final duty ratio DCfnl, the opening degree of the wastegate 30 can be feedback-controlled, and the boost pressure control component that opens and closes the wastegate 30 breaks down. When it is, the supercharging pressure control can be stopped.
[Failure diagnosis flow for boost pressure sensor]
[0046]
Next, a failure diagnosis flow for determining whether or not the boost pressure control component for controlling the opening and closing of the wastegate 30 shown in FIG. 2 is in a failure state will be described.
First, in step S31, the P correction term ΔCcp, the I correction term ΔCci, the control deviation ΔPmt, the correction upper limit value ΔCu that is failure determination data, and the correction lower limit value ΔCd obtained in the previous supercharging pressure control flow. The determination range upper limit value ΔPu and the determination range lower limit value ΔPd are input.
[0047]
Next, in steps S32 and S40, a failure determination A is performed to determine whether or not the correction term ΔCcpi, which is the sum of the P correction term ΔCcp and the I correction term ΔCci, is the correction upper limit value ΔCu or the correction lower limit value ΔCd. If it is normal, the process proceeds to step S50, and the upper limit side failure flag Fu and the lower limit side failure flag Fd are set to "0".
[0048]
If the correction term ΔCcpi is the correction upper limit value ΔCu in step S32, it is determined in step S33 whether the control deviation ΔPmt is greater than a predetermined determination range upper limit value ΔPu (eg, 10 kPa). If it is larger, it is counted in step S34 (Cu = Cu + 1), and when this large state continues for a predetermined time Tuc, the wastegate 30 has failed on the fully closed side in step S36. Is set to “1”. Note that Δt in FIG. 2 indicates a time interval at which this failure diagnosis flow is called.
[0049]
In other words, when the wastegate 30 is malfunctioning on the fully closed side, the correction term ΔCcpi takes a value close to 100% which is the duty ratio on the fully open side in order to move to the fully closed side. The measured boost pressure Pbm is larger than the target boost pressure Pbt. Accordingly, when the correction term ΔCcpi is 100%, which is the upper limit value ΔCu for correction, and the control deviation ΔPmt is larger than the predetermined determination range upper limit value ΔPu, the waste gate 30 has failed on the fully closed side. it can.
[0050]
Similarly, when the correction term ΔCcpi is the correction lower limit value ΔCd in step S40, it is determined in step S41 whether the control deviation ΔPmt is smaller than a predetermined determination range lower limit value ΔPd (eg, −10 kPa). If it is smaller and if it is smaller than the predetermined time Tdc by the counter Cd, the failure flag Fd on the lower limit side indicating that the wastegate 30 has failed on the fully open side is set to "1" in step S44. .
[0051]
That is, when the wastegate 30 is broken on the fully open side, the correction term ΔCcpi takes a value close to 0% that is the duty ratio on the fully closed side in order to move to the fully open side. The measured boost pressure Pbm is smaller than the target boost pressure Pbt. Therefore, when the correction term ΔCcpi is 0% which is the lower limit value ΔCd of the correction and the control deviation ΔPmt is smaller than the predetermined determination range lower limit value ΔPd, it is possible to detect that the wastegate 30 has failed on the fully open side. .
In step S39, the failure flags Fu and Fd as the failure diagnosis results are output and the process returns.
[0052]
According to the above fault diagnosis flow, when the correction value ΔCcpi (= ΔCcp + ΔCci) is the correction upper limit value ΔCu and the control deviation ΔPmt is greater than the predetermined determination range upper limit value ΔPu, It is determined that the boost pressure control component has failed on the fully closed side of the gate, the upper limit side failure flag Fu is set to “1”, the correction value ΔCcpi is the upper limit value ΔCd for correction, and the control When the deviation ΔPmt for use is smaller than the predetermined determination range lower limit value ΔPd, it is determined that the boost pressure control component has failed on the fully open side of the wastegate, and the lower limit side failure flag Fd is set to “1”. In other cases, the failure flags Fu and Fd can be set to “0”.
[0053]
When the correction amount ΔCcpi is the correction lower limit value ΔCd or the correction upper limit value ΔCu and the deviation ΔPmt is not within the predetermined determination range (ΔPd to ΔPu), it is determined that the supercharging pressure control component is out of order. Therefore, even when the wastegate 30 fails near the intermediate position, the failure can be detected.
[Control flow of fuel injection amount]
Further, the control flow of the fuel injection amount for controlling the fuel injection amount Qt of the engine shown in FIG. 3 will be described.
[0054]
First, in step S61, the engine load Ac, the rotational speed Ne, the maximum fuel injection amount Qmax, and the upper limit side failure flag Fu obtained in the previous failure diagnosis flow of the supercharging pressure control component are input.
[0055]
In step S62, the basic fuel injection amount Qb is calculated by referring to the three-dimensional map data Qb (Ac, Ne) from the engine load Ac and the engine speed Ne.
[0056]
Next, in steps S63, S64, and S65, the smaller value of the basic fuel injection amount Qb and the input maximum fuel injection amount Qmax is set as the upper limit fuel injection amount Qlm, and in step S66, the upper limit failure flag Fu is set. When the check is made and the waste gate 30 is malfunctioning on the fully closed side (Fu = 1), the fuel injection amount Qt is set to the upper limit fuel injection amount Qlm, and the malfunction is not occurring on the fully closed side (Fu = 0). In this case, the fuel injection amount Qt is a basic fuel injection amount Qb calculated from the engine load Ac and the engine rotational speed Ne.
[0057]
According to the control flow of the fuel injection amount described above, when the supercharging pressure control component has failed on the fully closed side of the wastegate 30 (Fu = 1), the fuel injection amount Qt is set to the maximum fuel injection amount Qmax and The upper limit Qlm can be set to a smaller value of the basic fuel injection amount Qb.
[0058]
Here, the maximum fuel injection amount Qmax is such that even if the wastegate 30 breaks down on the fully closed side and the supercharging pressure becomes excessive, the in-cylinder pressure is prevented from rising above the limit due to combustion, The amount does not damage the parts.
[0059]
〔effect〕
According to the above configuration, the correction amount ΔCcpi (= ΔCcp + ΔCci) for feedback control is obtained from the deviation ΔPmt between the measured boost pressure Pbm detected by the boost pressure sensor 21 and the target boost pressure Pbt by these boost pressure controls. ), And the correction ΔCcpi and deviation ΔPmt are compared with predetermined determination values ΔCd, ΔCu, ΔPd, ΔPu, respectively, to determine a failure of the supercharging pressure control component. When it is determined, the boost pressure control can be performed by feedback control using the correction amount ΔCcpi, and when it is determined that there is a failure in the failure determination, the boost pressure control can be controlled not to be performed. .
[0060]
When the correction value ΔCcpi is the correction upper limit value ΔCu and the control deviation ΔPmt is greater than the predetermined determination range upper limit value ΔPu, or when the correction value ΔCcpi is the correction lower limit value ΔCd and the control deviation When the case where the deviation ΔPmt is smaller than the predetermined determination range lower limit value ΔPd continues, it is possible to determine that the supercharging pressure control component is out of order when the wastegate is in the fully closed side or the fully open side, respectively.
[0061]
Therefore, it is possible to determine the failure of the supercharging pressure control component during engine operation, and in the event of a failure, the feedback control is stopped, and if the failure occurs on the fully closed side, an upper limit is set for the fuel injection amount. it can.
[0062]
In particular, not only the determination of the magnitude of the deviation ΔPmt between the measured supercharging pressure Pbm detected by the supercharging pressure sensor 21 and the target supercharging pressure Pbt, but also a correction that is a feedback correction term for control calculated from this deviation ΔPmt. Since the failure determination of the boost pressure control component is performed in combination with the determination of the value of the component ΔCcpi, even if the deviation ΔPmt is not large, the correction component ΔCcpi is inclined to one side of the open side or the closed side For example, a state in which the supercharging pressure control is not normally performed can be detected, and a more accurate failure determination can be performed.
[0063]
Then, when it is determined that the supercharging pressure control component has failed, the supercharging pressure control can be stopped, and it is possible to detect whether the wastegate 30 is fully closed or fully open. Since an upper limit can be set for the fuel injection amount Qt when there is a failure on the fully closed side, the fuel injection amount Qt is limited when there is a possibility of excessive supercharging due to a failure on the fully closed side Thus, the cylinder pressure can be prevented from increasing, and damage and destruction around the combustion chamber such as the cylinder can be prevented.
[0064]
【The invention's effect】
As described above, according to the control method for an engine with a turbocharger according to the present invention, when the engine is operating normally, the engine can be operated at an optimum boost pressure by feedback control when the engine is operating normally. In this case, the supercharging pressure control can be stopped.
[0065]
In particular, not only the magnitude of the deviation between the measured boost pressure detected by the boost pressure sensor and the target boost pressure, but also the correction value that is a feedback correction term for control calculated from this deviation Since the failure determination of the supercharging pressure control component is performed in combination with the above, more accurate failure determination can be performed.
[0066]
In other words, by adding this correction amount determination, even if the deviation between the measured supercharging pressure and the target supercharging pressure is not large, the state where the correction amount is inclined to one of the open side and the closed side continues for a predetermined time. In addition, a state where the supercharging pressure control is not normally performed can be detected.
[0067]
Further, it is detected whether the waste of the wastegate is on the open side or on the close side, and the fuel injection amount is determined only when the wastegate determines that the failure is on the close side where the supercharging pressure is excessive. If there is a possibility that excessive supercharging may occur due to a failure on the fully closed side, the fuel injection amount is limited to prevent the cylinder pressure from increasing, and the surroundings of the combustion chamber such as the cylinder Can be prevented from being damaged or destroyed.
[Brief description of the drawings]
FIG. 1 is a flowchart of supercharging pressure control according to the present invention.
FIG. 2 is a failure diagnosis flowchart of a supercharging pressure control component according to the present invention.
FIG. 3 is a control flowchart of a fuel injection amount according to the present invention.
FIG. 4 is a block diagram of supercharging pressure control according to the present invention.
FIG. 5 is a block diagram of control of the fuel injection amount according to the present invention.
FIG. 6 is a diagram showing a configuration of an engine according to the present invention.
[Explanation of symbols]
2 Intake passage
3 Exhaust passage
11 Turbocharger
11t turbine
11c compressor
13 Controller (ECM)
21 Boost pressure sensor
22 Intake sensor (mass airflow sensor)
23 Intake air temperature sensor
30 Westgate
E engine
Ne engine speed
Pb boost pressure
Pbb Basic supercharging pressure
Pbm measurement boost pressure
Pbt target boost pressure
DCbase basic duty ratio
DCfnl final duty ratio
ΔCcpi, ΔCcp, ΔCci Correction
ΔCd correction lower limit
ΔCu correction upper limit
ΔPmt deviation
ΔPd Predetermined judgment range lower limit
ΔPu Predetermined judgment range upper limit
Qt Target fuel injection amount
Qlm upper limit fuel injection amount
Tb Intake air temperature
Vb Intake air volume

Claims (3)

Adjustment of the opening degree of the wastegate provided with a turbocharger comprising a turbine provided in the exhaust passage and a compressor provided in the intake passage, and provided with a supercharging pressure sensor in the intake passage and bypassing the turbine provided in the turbocharger In a control method for an engine with a turbocharger that performs control by duty ratio control and controls supercharging pressure,
A basic supercharging pressure and a basic duty ratio corresponding to the basic supercharging pressure are calculated from the target fuel injection amount and the engine rotational speed, the basic supercharging pressure is corrected to calculate a target supercharging pressure, and the basic supercharging pressure is calculated. The final duty ratio is obtained by adding a correction amount calculated according to the deviation between the measured supercharging pressure detected by the supercharging pressure sensor and the target supercharging pressure to the duty ratio, and based on the final duty ratio While feedback controlling the opening of the wastegate,
An engine with a turbocharger, wherein when the correction amount is a correction lower limit value or a correction upper limit value and the deviation is not within a predetermined determination range, it is determined that a supercharging pressure control component is out of order. Control method. When the correction amount is a correction upper limit value and the deviation is larger than a predetermined determination range upper limit value, it is determined that a supercharging pressure control component has failed on the fully closed side of the waste gate,
When the correction amount is a correction lower limit value and the deviation is smaller than a predetermined determination range lower limit value, it is determined that the supercharging pressure control component has failed on the fully open side of the wastegate. A method for controlling a turbocharged engine according to claim 1. 3. The method of controlling a turbocharged engine according to claim 2, wherein when it is determined that a boost pressure control component has failed on the fully closed side of the wastegate, an upper limit is set for the target fuel injection amount.

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