JP2000345851A - Engine with turbo charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately detect failure of a boost pressure sensor, and switch a control method from a feed back control for using measured boost pressure into a following control for not using the measured boost pressure by comparing the measured boost pressure detected by the boost pressure sensor with an estimated boost pressure calculated from an intake air quantity and engine rotating speed. SOLUTION: An engine E is provided with a turbo charger 11 having a turbine 11t of an exhaust passage 3 and a compressor 11c of an intake passage 2, and boost pressure is controlled by an opening of a waist gate bypassing the turbine 11t. An operating condition of the engine E is controlled by a controller 13 on the basis of each detecting signal from a boost pressure sensor 21 disposed in the intake passage 2, a mass air flow sensor 22, and an intake temperature sensor 23. In this case, in a controller 13, an estimated boost pressure calculated from an intake air quantity and engine rotating speed and a measured boost pressure are compared with each other, the failure of the boost pressure sensor 21 is judged, and a control method is switched from a feed back control into a follow control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boost pressure sensor provided in an intake passage. The boost pressure measured by the boost pressure sensor is input to the boost pressure sensor to determine the opening degree of a wastegate provided in a turbocharger. The present invention relates to a turbocharged engine for controlling a supercharging pressure.

More specifically, the present invention relates to a turbocharged engine capable of performing a failure diagnosis of a boost pressure sensor and controlling a boost pressure at the time of failure.

[0003]

2. Description of the Related Art In an engine equipped with a turbocharger such as a passenger car, a bus or a truck, as shown in FIG. 4, an exhaust gas discharged from an engine E drives a turbine 11t on an exhaust passage 3 side. To turbine 11t
By rotating the compressor 11c on the side of the intake passage 2 connected coaxially with the compressor, the intake air is pressurized to supercharge the intake air.

In this turbocharger 11, the supercharging pressure Pb is set to a preset maximum supercharging pressure in order to prevent the cylinder E from being damaged due to excessive supercharging when the engine E is rotated at a high speed. When the pressure exceeds the pressure, a wastegate 30 is provided for adjusting a supercharging pressure Pb by bypassing a part of the exhaust gas from the turbine 11t.

Further, by controlling the opening degree of the waste gate 30, the supercharging pressure Pb is controlled, for example,
The operating state of the engine E is determined from the target fuel injection amount and the engine rotational speed Ne so that the supercharging pressure Pb becomes optimal for this operating state.

That is, a supercharging pressure (intake pressure) sensor 21 is provided in the intake passage 2, and the supercharging pressure sensor 21 detects an actual supercharging pressure (intake pressure). In order to approach the pressure, a so-called feedback control is performed in which control is performed in accordance with a 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 as the control target.

For adjusting the opening of the waste gate 30, a vacuum chamber 34 and a vacuum chamber 34 connected to a diaphragm to which the waste gate valve 30b is connected are connected by an air pipe 32, and the air pipe 32 is controlled to be opened and closed by a controller 13. An electromagnetic variable adjustment valve (EVRV) 33 is provided.

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 adjusting valve 33 and adjusting the pressure of the negative pressure chamber of the diaphragm. The waist gate valve 30b is lifted and the waste gate 30 is opened as the internal pressure of the negative pressure chamber of the diaphragm communicating with the vacuum pump 34 is reduced.

[0009]

The feedback control of the supercharging pressure is based on the premise that the actual supercharging pressure in the intake passage is detected. However, a supercharging pressure sensor for detecting the actual supercharging pressure is used. May fail due to component deterioration or poor connection of wiring, and the boost pressure may not be detected normally. If the failure of the supercharging pressure sensor occurs during the supercharging pressure control operation of the engine, the supercharging pressure feedback control is not performed normally, and the supercharging pressure becomes excessively large or small. In particular, when the supercharging pressure becomes excessive, abnormal combustion occurs and the in-cylinder pressure becomes too high, so that components around the combustion chamber are damaged.

However, the conventional turbocharged engine which performs the supercharging pressure control does not have a means for detecting a failure state of the supercharging pressure sensor. Occurs, the failure cannot be detected and the boost pressure control cannot be switched at the time of the failure, so that the boost pressure control is continued based on incorrect boost pressure information. There's a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to determine whether a supercharge pressure sensor is normal or abnormal during operation of a turbocharged engine that performs supercharge pressure control. Provided is a turbocharged engine that can perform feedback control based on the measured supercharging pressure if it is normal, determine failure if it is abnormal, and perform follow-up control regardless of the measured supercharging pressure. That is.

[0012]

An engine with a turbocharger for achieving the above object is configured as follows. 1) In a turbocharged engine that includes a turbocharger and a supercharging pressure sensor and controls the supercharging pressure by inputting the measured supercharging pressure, the measurement detected by the supercharging pressure sensor The supercharging pressure is compared with an estimated supercharging pressure estimated from an operation state of the engine, and a failure judgment of the supercharging pressure sensor is performed. When the failure determination determines that the supercharging pressure is normal, the supercharging pressure is determined. The feedback control using the measured supercharging pressure detected by the sensor performs the supercharging pressure control, and when the failure is determined to be a failure in the failure determination, the measured supercharging pressure detected by the supercharging pressure sensor is used. An engine with a turbocharger, which performs supercharging pressure control by following control that is not performed.

2) A wastegate having a turbocharger including a turbine provided in an exhaust passage and a compressor provided in an intake passage, and having a supercharging pressure sensor in an intake passage, and bypassing a turbine provided in the turbocharger. In a turbocharged engine that controls the supercharging pressure based on the opening degree of the engine, an estimated supercharging pressure is calculated from an intake air amount detected by an intake air amount sensor provided in the intake passage and an engine rotation speed detected by an engine rotation speed sensor. And
A failure of the supercharging pressure sensor is determined by comparing the estimated supercharging pressure with a measured supercharging pressure detected by the supercharging pressure sensor, and when it is determined that the supercharging pressure sensor is normal, a target The basic supercharging pressure is calculated from the fuel injection amount and the engine rotation speed, the target supercharging pressure is calculated by correcting the basic supercharging pressure, and the basic supercharging pressure is detected by the supercharging pressure sensor. An operating boost pressure is calculated by adding a correction amount calculated in accordance with a deviation between the measured boost pressure and the target boost pressure, and the opening degree of the wastegate is feedback-controlled based on the operating boost pressure. If it is determined that the supercharging pressure sensor is malfunctioning, the basic supercharging pressure is set to the value of the operation supercharging pressure, and the opening degree of the wastegate is controlled based on the operation supercharging pressure. It is configured to

According to the above configuration, the failure judgment of the supercharging pressure sensor is performed by comparing the intake air amount with the estimated supercharging pressure obtained from the engine speed. Feedback control using supercharging pressure
It is possible to control to the optimal boost pressure,
The feedback control is switched to the follow-up control so that the measured boost pressure detected by the failed boost pressure sensor is not used for the control. Prevent supply pressure from occurring.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. [Overall Configuration] An engine E shown in FIG. 4 is an engine E in which a turbocharger 11 provided with a turbine 11t in an exhaust passage 3 and a compressor 11c in an intake passage 2 is arranged. The turbocharger 11 bypasses the turbine 11t. It has a wastegate 30 and is configured to control the supercharging pressure Pb by the opening degree of the wastegate 30.

Further, a supercharging pressure sensor 21, a mass air flow sensor (intake air amount sensor) 22, an intake air temperature sensor
23, the measured supercharging pressure Pbm detected by these sensors 21, 22, and 23, the intake air amount Vb, the intake temperature Tb, and the engine speed N detected by a rotation speed sensor (not shown).
A controller (ECM) 13 for inputting e and the like and controlling overall operation of the engine is provided.

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 solenoid valve (EVRV: electric) by the air pipe 32. -It is configured to be connected to a vacuum pump 34 via a variable regulation valve (electromagnetic variable adjustment valve) 33.

The opening and closing of the solenoid valve 33 is controlled by a predetermined duty signal (pulse drive signal) output from the controller 13, and the opening and closing amount is used to adjust the pressure of the negative pressure chamber 30a. By lowering the internal pressure, the valve 30b for opening and closing the bypass passage 30c of the wastegate 30 is lifted to increase the opening.

The vacuum pump 34 is also used for controlling the opening and closing 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 includes a failure diagnosis flow of the supercharging pressure sensor of FIG. 1 and a supercharging pressure control flow of FIG. The controller (ECM) 13 is configured as a part of engine operation control. FIG. 3 is a block diagram corresponding to the supercharging pressure control flow of FIG.

Further, these flows merely exemplify one example, and the control according to the present invention can be performed by another flow, and the present invention is not limited to these flows. Further, in the implementation, averaging or the like is performed to remove noise from the detection data such as the measured supercharging pressure. However, these work parts are excluded in the flow of FIG. 1 and the like in order to make the control flow easier to understand. Is shown.

The failure diagnosis flow of the supercharging pressure sensor shown in FIG. 1 and the supercharging pressure control flow shown in FIG. 2 are repeatedly called as necessary from the main control flow for controlling the entire operation of the engine. Yes, and is performed as follows: [Failure Diagnosis Flow of Supercharging Pressure Sensor] First, a failure diagnosis flow for determining whether the supercharging pressure sensor 21 shown in FIG. 1 is in a failure state will be described.

First, in step S31, a measured supercharging pressure (actual supercharging pressure) Pbm, an intake air amount Vb, an engine rotation speed Ne, and an intake air temperature Tb are input from the supercharging pressure sensor 21.

Next, at steps S32 and S33, the estimated supercharging pressure P
Calculate be. This is because, in step S32, the intake air amount Vb detected by the mass airflow sensor 22 and the engine speed Ne detected by an engine speed sensor (not shown).
The basic estimated supercharging pressure Pbeo is calculated with reference to the three-dimensional map data (Vb, Ne → Pbeo) from
Then, the basic estimated supercharging pressure Pbeo is calculated by subtracting 2 from the intake air temperature Tb.
The estimated boost pressure Pbe is calculated by multiplying the correction coefficient Kt calculated with reference to the dimensional map data (Tb → Kt).

Next, at steps S34 to S39, the supercharging pressure sensor
Perform 21 failure determinations. This is because the difference ΔPme = | Pbm−Pbe | between the measured supercharging pressure Pbm and the estimated supercharging pressure Pbe is larger than a predetermined failure determination value ΔPc, and the state where the difference ΔPme is large continues for a predetermined time Tc or more. Is determined to be a failure, and the failure flag F is set to "1".

That is, in step S34, it is determined whether or not the deviation ΔPme is larger than the failure determination value ΔPc, and if it is, in step S35, one counter C is added and counted to measure the duration Tt. I do.

Then, in the next step S36, the duration Tt
It is determined whether the counter C has exceeded the predetermined number of times Cc by determining whether the counter C has exceeded the predetermined number of times Cc. If the counter C has exceeded the predetermined number of times Cc, it is determined that the supercharging pressure sensor 21 is in a failure state. Then, the process proceeds to a step S37, in which a failure flag F indicating a failure of the supercharging pressure sensor 21 is set to "1".

If it is determined in step S36 that the counter C has not exceeded the predetermined number Cc, the continuation time T
Since t is insufficient, it is determined that there is no failure, and the process proceeds to step S39, where the failure flag F is set to "0" indicating a normal state, and the routine returns.

Also, in the determination of step S34, the deviation ΔPme
Is smaller than the failure determination value ΔPc, it is determined to be normal, the counter C is set to “0” in step S38, the failure flag F is set to “0” indicating a normal state in step S39, and the routine returns. .

Also, once in step S34, the deviation ΔPme
Is longer than the failure determination value ΔPc,
Is smaller than the failure determination value ΔPc before the predetermined time Tc has elapsed, it is determined that the state is normal and C = 0 and F = 0 via steps S38 and S39.

In accordance with the above-described fault diagnosis flow, a fault determination is made. If a fault has occurred, the fault flag F is set to "1", and if not, a "0" is set. [Supercharging Pressure Control Flow] Next, a supercharging pressure control flow including the feedback control and the follow-up control shown in FIGS. 2 and 3 will be described.

In this supercharging pressure control flow, the supercharging pressure sensor
If the failure occurs, the operation supercharging pressure Pbf, which is the operation amount, is set to the basic supercharging pressure Pbb. If the supercharging pressure sensor 21 is normal and the control deviation ΔPmt is larger than the predetermined value ΔPk, the feedback of PI control is performed. When the control is performed and the supercharging pressure sensor 21 is normal and the control deviation ΔPmt is smaller than the predetermined value ΔPk, the correction amounts ΔPcp and ΔPci in the feedback control are set to be the same as the previous control.

That is, when the supercharging pressure sensor 21 is normal, the supercharging pressure Pb is controlled by a control amount, the target supercharging pressure Pbt is a target value, and a pulse drive signal for duty ratio control calculated from the operating supercharging pressure Pbf is operated. As a signal, feedback control is performed using the wastegate 30 as a control element. When the supercharging pressure sensor 21 is abnormal, the supercharging pressure Pb is calculated from the control amount and the basic supercharging pressure Pbb (= operation supercharging pressure Pbf). Following control is performed using the waste gate 30 as a control element, with a pulse drive signal for duty ratio control as an operation signal.

First, when this supercharging pressure control flow is called and started, in step S10, the target fuel injection amount Qt
, The engine rotation speed Ne, the intake air temperature Tb, and the failure flag F, and in step S11, the three-dimensional map data Pbb (Q) is obtained from the target fuel injection amount Qt and the engine rotation speed Ne.
The basic supercharging pressure Pbb is calculated with reference to (t, Ne).

Next, the failure flag F is checked in step S12.
When the failure flag F is set (F = 1),
That is, when the supercharging pressure sensor 21 is out of order, the process proceeds to step S24 without performing the feedback control, and sets the operating supercharging pressure (final supercharging pressure) Pbf to the basic supercharging pressure Pbb. The opening degree of the gate 30 is adjusted and controlled to follow the supercharging pressure Pb.

If the failure flag F has not been set (F = 0), that is, if the supercharging pressure sensor 21 has not failed, the routine proceeds to step S13, where the correction terms ΔPcp and ΔPci of the operating supercharging pressure Pbf are calculated. And perform feedback control.

First, in step S13, the measured supercharging pressure Pbm is input from the supercharging pressure sensor 21, and in step S14, the basic supercharging pressure Pbb is corrected by the intake air temperature Tb and the atmospheric pressure Pa. That is, the target supercharging pressure Pbt is calculated by multiplying the basic supercharging pressure Pbb by the correction coefficient Kt (Tb) and further adding the correction coefficient Kp (Pa).

Next, in step S15, a deviation ΔPmt (= Pbm−Pbt) between the measured supercharging pressure Pbm and the target supercharging pressure Pbt is calculated, and in step S16, the absolute value of the deviation ΔPmt becomes a predetermined control determination value ΔPk. It is determined whether or not it has exceeded.

The absolute value of the deviation ΔPmt is equal to the control determination value Δ
If it exceeds Pk, the process proceeds to step S17 to calculate a correction amount corresponding to the deviation ΔPmt, and if not, the process proceeds to step S20.

In step S17, a P correction term ΔPcp for proportionally correcting the deviation ΔPmt is obtained by multiplying the deviation ΔPmt by the correction coefficient Kp of the P correction term. In step S18, the deviation Δ
The I correction term ΔPci for integration correction of Pmt is multiplied by the correction coefficient Ki of the I correction term, and further obtained by adding the previous I correction term ΔPcim.

Next, at step S19, the operating boost pressure Pbf is calculated by adding the P correction term ΔPcp and the I correction term ΔPci to the basic boost pressure Pbb determined at step S11.

If it is determined in step S16 that the absolute value of the deviation ΔPmt does not exceed the predetermined control determination value ΔPk, the deviation ΔPmt is small, the measured supercharging pressure Pbm is close to the target supercharging pressure Pbt, and Since there is no need to calculate the correction amount in step (a), the process proceeds to steps S20 and S21 without calculating new correction amounts ΔPcp and ΔPci, and uses the previous P correction term ΔPcpm and I correction term ΔPcim.

Then, the process proceeds to step S22, where
An operating supercharging pressure Pbf is calculated by adding the basic supercharging pressure Pbb obtained in step 11, the P correction term ΔPcp and the I correction term ΔPci calculated in steps S20 and S21.

Then, in step S25, the control supercharging pressure Pbf for control is converted into a pulse drive signal for duty ratio control, and this pulse drive signal is output to an electromagnetic valve (EVRV) to open the waste gate 30. By adjusting the degree,
The system is configured to perform feedback control of the supercharging pressure Pb.

In the present embodiment, the correction according to the deviation ΔPmt between the measured supercharging pressure Pbm and the target supercharging pressure Pbt is performed by the PI control. ) Or only the I (integral) term, or D (differential) correction may be additionally combined.
That is, P, I, PI, PD, and PID control may be used. [Control Flow] The supercharging pressure Pb is controlled as described above. According to these supercharging pressure controls, the supercharging pressure Pb is estimated from the intake air amount Vb detected by the mass airflow sensor 22 and the engine rotation speed Ne. The supercharging pressure Pbe is calculated, and a failure of the supercharging pressure sensor 21 can be determined by comparing the estimated supercharging pressure Pbe with the measured supercharging pressure Pbm.

A basic supercharging pressure Pbb and a corrected target supercharging pressure Pbt are calculated from the target fuel injection amount Qt and the engine speed Ne, and the basic supercharging pressure Pbb is detected by a supercharging pressure sensor. The operating supercharging pressure Pbf is obtained by adding a correction amount calculated according to the deviation ΔPmt between the measured supercharging pressure Pbm and the target supercharging pressure Pbt, and the opening of the waist 30 is determined based on the operating supercharging pressure Pbf. The degree can be adjusted and controlled.

At the same time, when it is determined that the supercharging pressure sensor 21 has failed, the basic supercharging pressure Pbb is set to the value of the operating supercharging pressure Pbf,
The opening degree of the wastegate 30 can be controlled to follow based on the operation supercharging pressure Pbf. [Effect] Therefore, according to the above configuration, when the engine is operating, the failure of the supercharging pressure sensor 21 is determined based on the estimated supercharging pressure Pbe and the measured supercharging pressure Pbm obtained from the intake air amount Vb and the engine speed Ne. Are compared, the supercharging pressure sensor 21
In case of failure, the feedback control is stopped and the control is switched to the follow-up control. Therefore, it is possible to prevent the opening degree of the wastegate 30 from being adjusted and controlled by the operation supercharging pressure Pbt calculated from the erroneous measured supercharging pressure Pbm.

As a result, excessive supercharging can be avoided, so that troubles such as abnormal combustion can be prevented, and damage and destruction around the combustion chamber such as the cylinder can be prevented.

It is to be noted that a method of substituting the estimated supercharging pressure Pbe obtained from the intake air amount Vb and the engine rotation speed Ne as the measured supercharging pressure Pbm may be used. In this case, there is a possibility that the intake air amount Vb changes and the estimated supercharging pressure Pbe shifts. Therefore, in the present invention, this method is not adopted, and the basic supercharging pressure Pbe is used instead of the estimated supercharging pressure Pbe (← Vb, Ne, Tb).
bb (← Qt, Ne, Tb, Pa) is set as the operating supercharging pressure Pbf at the time of failure, and this is avoided.

[0049]

As described above, according to the engine with a turbocharger of the present invention, the following effects can be obtained.

First, during the operation of the engine, the supercharging pressure measured by the supercharging pressure sensor is compared with the estimated supercharging pressure obtained from the intake air amount and the engine speed to determine whether the supercharging pressure sensor has failed. Therefore, when the boost pressure sensor fails, the failure can be immediately detected, and the feedback control using the measured boost pressure can be switched to the follow-up control without using the measured boost pressure.

At the time of normal judgment, feedback control is performed using the measured supercharging pressure detected by the supercharging pressure sensor.
It is possible to control to the optimal boost pressure,
The feedback control is switched to the follow-up control so that the measured boost pressure detected by the failed boost pressure sensor is not used for the control. It is possible to prevent supply pressure from being generated.

Therefore, during normal operation of the engine, it is possible to operate at an optimum boost pressure by feedback control under normal conditions, and if the boost pressure sensor fails, the wastegate sensor detects an incorrect boost pressure based on an erroneous measured boost pressure. Adjustment control of the opening can be avoided, the engine can be protected by preventing improper supercharging such as excessive supercharging, etc., and it is performed based on the basic supercharging pressure estimated from the operating state of the engine. By the follow-up control, the operation can be continued at a substantially appropriate boost pressure.

[Brief description of the drawings]

FIG. 1 is a flowchart of a failure diagnosis of a supercharging pressure sensor according to the present invention.

FIG. 2 is a flowchart of a supercharging pressure feedback control according to the present invention.

FIG. 3 is a block diagram of supercharging pressure control according to the present invention.

FIG. 4 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 Supercharging pressure sensor 22 Intake air amount sensor (mass airflow sensor) 23 Intake temperature sensor 30 Westgate E Engine Ne Engine rotation speed Pb Supercharging pressure Pbb Basic supercharging pressure Pbe Estimated supercharging pressure Pbf Operating supercharging pressure Pbm Measured supercharging pressure Pbt Target supercharging pressure ΔPmt Deviation ΔPcp, ΔPci Correction Qt Target fuel injection amount Tb Intake temperature Vb Intake air amount

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomio Nishikawa 8 Tsuchiya, Fujisawa City, Kanagawa Prefecture Isuzu Motors Fujisawa Plant F-term (reference) 3G005 EA04 EA16 FA25 GA02 GB27 GC05 GC07 GD28 GE02 GE08 GE09 GE10 JA11 JA24 JA39 JA45

Claims (2)

[Claims] 1. An engine with a turbocharger, comprising a turbocharger and a supercharging pressure sensor, for controlling a supercharging pressure by inputting a measured supercharging pressure detected by the supercharging pressure sensor. The detected supercharging pressure is compared with an estimated supercharging pressure estimated from the operating state of the engine, and a failure determination of the supercharging pressure sensor is performed.If it is determined that the failure determination is normal, The supercharging pressure is controlled by feedback control using the measured supercharging pressure detected by the supercharging pressure sensor. If the failure is determined to be a failure in the failure determination, the measured supercharging detected by the supercharging pressure sensor is performed. An engine with a turbocharger that performs supercharging pressure control by following control without using pressure. A turbocharger comprising a turbine provided in an exhaust passage and a compressor provided in an intake passage;
And a turbocharged engine having a supercharging pressure sensor in an intake passage and controlling a supercharging pressure by an opening degree of a wastegate bypassing a turbine provided in the turbocharger. The estimated supercharging pressure is calculated from the intake air amount detected in the above and the engine rotation speed detected by the engine rotation speed sensor, and the estimated supercharging pressure is compared with the measured supercharging pressure detected by the supercharging pressure sensor to calculate the supercharging pressure. When the supercharging pressure sensor is determined to be faulty, and when it is determined that the supercharging pressure sensor is normal, a basic supercharging pressure is calculated from the target fuel injection amount and the engine speed, and the basic supercharging pressure is calculated. The target boost pressure is calculated by correcting the boost pressure, and a correction amount calculated according to a deviation between the measured boost pressure detected by the boost pressure sensor and the target boost pressure is added to the basic boost pressure. And operate The boost pressure is obtained, and the opening degree of the wastegate is feedback-controlled based on the operation boost pressure. If it is determined that the boost pressure sensor is malfunctioning, the basic boost pressure is reduced to the operation boost pressure. An engine with a turbocharger, wherein a pressure value is set, and the opening of the wastegate is tracked and controlled based on the operation supercharging pressure.