JP2023069127A - monitoring device - Google Patents

Abstract

To provide a monitoring device capable of easily securing reliability of an estimation value of output torque of an internal combustion engine.SOLUTION: A monitoring device includes: a first monitoring section that compares a first estimation value of output torque of an internal combustion engine estimated from a detection value of an opening of a throttle valve provided in an intake passage of the internal combustion engine with a required value of output torque required for the internal combustion engine to monitor normality of the first estimation value; and a second monitoring section that compares a second estimation value of output torque of the internal combustion engine estimated from a detection value of intake air amount sucked from the intake passage with the first estimation value when the first monitoring section confirms the normality of the first estimation value to monitor normality of the second estimation value. The required value is a parameter satisfying a predetermined standard related to reliability.SELECTED DRAWING: Figure 3

Description

The present invention relates to monitoring devices.

A hybrid vehicle is provided with an engine (internal combustion engine) and a motor (electric motor) that output torque for driving the vehicle (see Patent Document 1, for example). The motor is required to have remaining torque obtained by subtracting the estimated output torque of the engine from the torque required according to the operation of the vehicle driver. Therefore, in order to properly control the torque of the motor, it is necessary to monitor that the estimated value of the output torque is highly accurate and reliable.

JP 2020-111276 A

For example, when estimating the estimated value of the output torque from the detected value of the intake air amount of the engine detected by the airflow meter, the estimated value can be calculated with high accuracy. Also, as an indicator of the reliability of the estimated value, for example, there is an automotive safety integrity level (ASIL) defined by ISO (International Organization for Standardization) 26262.

However, calculating the estimated output torque from the detected value of a sensor such as an airflow meter requires a large number of parameters and complicated arithmetic processing. Conceivable.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a monitoring device capable of easily ensuring the reliability of an estimated value of the output torque of an internal combustion engine.

The monitoring device of the present invention calculates a first estimated value of the output torque of the internal combustion engine estimated from a detected value of the opening of a throttle valve provided in an intake passage of the internal combustion engine, and calculates the output torque required for the internal combustion engine. and a first monitoring unit for monitoring the normality of the first estimated value by comparing with the required value of the intake air, and when the first monitoring unit confirms the normality of the first estimated value, the air is drawn from the intake passage. a second monitoring unit that monitors normality of the second estimated value by comparing the second estimated value of the output torque of the internal combustion engine estimated from the detected value of the intake air amount with the first estimated value; and the required value is a parameter that satisfies a predetermined criterion for reliability.

ADVANTAGE OF THE INVENTION According to this invention, the reliability of the estimated value of the output torque of an internal combustion engine can be ensured easily.

1 is a configuration diagram showing an example of a vehicle system; FIG. 1 is a configuration diagram showing an example of an engine ECU (Electronic Control Unit); FIG. 7 is a flowchart showing an example of an estimated torque monitoring process;

(Vehicle system configuration)
FIG. 1 is a configuration diagram showing an example of the vehicle system 9. As shown in FIG. The vehicle system 9 is mounted on a hybrid vehicle, for example, and has a vehicle ECU 6 , an accelerator sensor 60 , a brake sensor 61 , a vehicle speed sensor 62 , an engine system 90 , a motor system 91 , a differential gear device 50 , axles 52 and wheels 53 .

An accelerator sensor 60 detects the opening of an accelerator pedal (not shown), and a brake sensor 61 detects the opening of a brake pedal (not shown). A vehicle speed sensor detects the speed of the hybrid vehicle. The accelerator sensor 60, the brake sensor 61, and the vehicle speed sensor 62 output detection values to the vehicle ECU6.

The vehicle ECU 6 calculates the torque required for the hybrid vehicle from the detection values of the accelerator sensor 60, brake sensor 61, vehicle speed sensor 62, and the like.

The engine system 90 has an engine ECU 1 , an engine 2 , an intake passage 20 , an exhaust passage 21 , an air cleaner 22 , an airflow meter 23 , a throttle valve 24 and a throttle opening sensor 25 . An air cleaner 22 is provided at one end of the intake passage 20 and filters outside air. Outside air flows through an intake passage 20 and is taken into the combustion chamber of the engine 2 . Exhaust gas generated by combustion is discharged outside the vehicle from an exhaust passage 21 through a catalyst device (not shown) and the like.

An airflow meter 23 and a throttle valve 24 are provided in the intake passage 20 . The airflow meter 23 is located upstream of the throttle valve 24 and detects the amount of intake air in the intake passage 20 . The airflow meter 23 outputs the detected value of the intake air amount to the engine ECU 1 .

The opening degree of the throttle valve 24 is controlled by the engine ECU1. A throttle opening sensor 25 detects the opening of the throttle valve 24 . A throttle opening sensor 25 outputs a detected value of the opening of the throttle valve 24 to the engine ECU 1 .

The sensor system 26 includes multiple sensors that detect various parameters related to the operating state of the engine 2 . The parameters include the number of revolutions of the engine 2, the temperature of the cooling water, the temperature of the intake air, the atmospheric pressure, the pressure of each part of the engine 2, and the like. The sensor system 26 outputs each detected value to the engine ECU 1 .

The engine ECU 1 controls the operation of the engine 2 based on the detection values of the sensor system 26 , the airflow meter 23 and the throttle opening sensor 25 . The engine ECU 1 receives a command for torque required for the engine 2 (hereinafter referred to as engine required torque Treq) from the vehicle ECU 6 . The engine ECU 1 controls the fuel injection timing and ignition timing of the engine 2 and the opening degree of the throttle valve 24 so that the output torque of the engine 2 approaches the engine required torque. Note that the engine 2 is an example of an internal combustion engine. Also, the engine demand torque Treq is an example of a demand value of the output torque demanded of the engine 2 .

The motor system 91 has a motor ECU 3 , an inverter 30 , a motor 31 , a boost converter 32 and a battery 33 . The battery 33 is, for example, a lithium ion battery, and supplies power to the motor 31 . Boost converter 32 boosts the voltage of battery 33 and applies it to inverter 30 . Inverter 30 converts the DC current input from boost converter 32 into a three-phase AC current and outputs the three-phase AC current to motor 31 . The motor 31 rotates a rotor (not shown) with a three-phase alternating current.

A motor ECU 3 controls the operation of the motor 31 . The motor ECU 3 receives, from the vehicle ECU 6 , a command for the torque required for the motor 31 from the vehicle ECU 6 (hereinafter referred to as “motor required torque”). The engine ECU 1 controls the inverter 30 and the boost converter 32 by switching signals so that the output torque of the motor 31 approaches the motor required torque. The vehicle ECU 6, the engine ECU 1, and the motor ECU 3 communicate with each other via a communication line conforming to CAN (Controller Area Network) standards, for example.

Each rotating shaft of the engine 2 and the motor 31 is connected to a differential gear device 50 via a power transmission mechanism (not shown). A differential gear device 50 is connected to an axle 52 that rotates wheels 53 . Thereby, the hybrid vehicle is driven by each output torque of the engine 2 and the motor 31 .

The vehicle ECU 6 determines the distribution of the output torques of the engine 2 and the motor 31 . The vehicle system 9 first calculates the engine demand torque Treq from the detection values of the accelerator sensor 60, the brake sensor 61, and the vehicle speed sensor 62, and instructs the engine ECU 1 to calculate it. The engine demand torque Treq is a highly reliable parameter that satisfies ASIL, for example.

That is, the engine demand torque Treq is calculated based on a highly reliable design defined by ISO26262. For this reason, the vehicle ECU 6 that calculates the engine demand torque Treq uses, for example, a memory and a power supply circuit with a low failure rate, and is also equipped with memory redundancy and communication error correction functions.

As a result, the engine demand torque Treq is less likely to become an abnormal value (error value) due to component failure or the like than other parameters that do not satisfy the ASIL standard. Conversely, since the engine demand torque Treq satisfies the ASIL standard, it is more likely that it will be a normal value than other parameters that do not satisfy the ASIL standard. Note that ASIL is an example of a predetermined standard for reliability.

The engine ECU 1 controls the engine 2 according to the engine demand torque Treq. The engine ECU 1 estimates the output torque of the engine 2 and notifies the vehicle ECU 6 of the estimated value (hereinafter referred to as estimated torque).

Tm=Tvh-Te (1)

The vehicle ECU 6 calculates the required motor torque Tm from the estimated torque Te. In equation (1), Tvh is torque required according to the driver's operation of the hybrid vehicle (hereinafter referred to as vehicle torque).

In this way, the motor 31 is required to have the remaining required torque Tm obtained by subtracting the estimated torque Te from the vehicle torque Tvh. Therefore, in order for the motor ECU 3 to appropriately control the torque of the motor 31, the engine ECU 1 monitors the normality of the estimated torque Te. Note that the engine ECU 1 is an example of a monitoring device.

(Configuration of engine ECU)
FIG. 2 is a configuration diagram showing an example of the engine ECU 1. As shown in FIG. The engine ECU 1 is an example of a computer and has a CPU (Central Processing Unit) 10 , a ROM (Read Only Memory) 11 , a RAM (Random Access Memory) 12 and an input/output port 13 . The CPU 10 is electrically connected to a ROM 11, a RAM 12, and an input/output port 13 via a bus 19 so as to input/output signals to/from each other.

ROM 11 stores a program for driving CPU 10 . The RAM 12 functions as working memory for the CPU 10 . The input/output port 13 relays communication between the CPU 10, the vehicle ECU 6, the sensor system 26, the airflow meter 23, the throttle valve 24, and the throttle opening sensor 25.

When the CPU 10 reads a program from the ROM 11, it functions as an operation control section 100, a required torque acquisition section 101, a torque estimation section 102, a throttle base torque monitoring section 103, an estimated torque monitoring section 104, and an engine control section 105. . The operation control unit 100 instructs the required torque acquisition unit 101, the torque estimation unit 102, the throttle base torque monitoring unit 103, the estimated torque monitoring unit 104, and the engine control unit 105 to perform various processes in accordance with the sequence specified in the program. . Further, the operation control unit 100 inputs/outputs parameters necessary for each process to/from the required torque acquisition unit 101, the torque estimation unit 102, the throttle base torque monitoring unit 103, the estimated torque monitoring unit 104, and the engine control unit 105. do.

The required torque acquisition unit 101 acquires the engine required torque Treq from the vehicle ECU 6 via the input/output port 13 .

A torque estimator 102 estimates the output torque of the engine 2 . The torque estimator 102 calculates the torque of the engine 2 according to a predetermined calculation formula based on the detected value of the throttle opening sensor 25, the detected values of pressure and temperature upstream and downstream of the throttle valve 24, and the ignition timing of the spark plug of the engine 2. An estimated value of output torque (hereinafter referred to as throttle base torque Tt) is calculated. The throttle base torque Tt is an example of a first estimated value of the output torque of the engine 2 estimated from the detected value of the opening of the throttle valve 24 .

Further, the torque estimator 102 calculates the estimated torque Te according to a predetermined calculation formula from the detected value of the airflow meter 23 and the ignition timing of the ignition plug of the engine 2 . The estimated torque Te is an example of a second estimated value of the output torque of the engine 2 estimated from the detected value of the amount of intake air drawn from the intake passage 20 .

Since the detected value of the airflow meter 23 is the amount of intake air from the intake passage 20 to the engine 2 , it has a stronger correlation with the output torque of the engine 2 than the opening of the throttle valve 24 . Therefore, the estimated torque Te is closer to the actual output torque than the throttle base torque Tt and has high accuracy. Therefore, the vehicle ECU 6 calculates the motor request torque Tm from the estimated torque Te by the above equation (1).

The engine control unit 105 controls the opening of the throttle valve 24, the injection amount of fuel to the engine 2, the ignition timing of the engine 2, and the like based on the engine request torque Treq. At this time, the detected value of the airflow meter 23 changes according to the opening of the throttle valve 24 . Therefore, the throttle base torque Tt and the estimated torque Te change according to the engine demand torque Treq as a response to the control of the engine control unit 105 .

Although the throttle base torque Tt and the estimated torque Te are more accurate than the engine demand torque Treq, they do not meet the ASIL criteria, so they are less reliable than the engine demand torque Treq which satisfies the ASIL criteria. Since the throttle base torque Tt and the estimated torque Te require many parameters and complicated arithmetic processing, it is difficult to satisfy the ASIL standard.

Therefore, the engine ECU 1 ensures the reliability of the estimated torque Te by performing stepwise comparison as follows.

The throttle base torque monitoring unit 103 is an example of a first monitoring unit, and monitors the normality of the throttle base torque Tt by comparing the throttle base torque Tt with the engine demand torque Treq. Here, the engine demand torque Treq is a highly reliable parameter that satisfies the ASIL standard.

Further, when the engine ECU 1 is normal, the opening degree of the throttle valve 24 is controlled by the engine control section 105 based on the engine required torque Treq. Therefore, the engine demand torque Treq has a stronger correlation with the throttle base torque Tt than with the estimated torque Te.

Therefore, the throttle base torque monitoring unit 103 can determine the normality of the throttle base torque Tt by comparing it with the engine demand torque Treq. For example, the throttle base torque monitoring unit 103 determines that the throttle base torque Tt is normal when the difference (absolute value) between the throttle base torque Tt and the engine demand torque Treq is less than a predetermined threshold value Ka.

As a result, the throttle base torque Tt can be regarded as a parameter that satisfies the ASIL standard in the same manner as the engine demand torque Treq. Therefore, the throttle base torque monitoring unit 103 can ensure the reliability of the throttle base torque Tt by determining that the throttle base torque Tt is normal.

Estimated torque monitoring unit 104 is an example of a second monitoring unit. When throttle base torque monitoring unit 103 determines that throttle base torque Tt is normal, estimated torque Te is compared with throttle base torque Tt. monitor the health of Here, the throttle base torque Tt does not satisfy the ASIL standard, but as described above, the reliability of the throttle base torque Tt is ensured by comparison with the engine demand torque Treq which satisfies the ASIL standard.

Also, the throttle base torque Tt and the estimated torque Te are responses to the control of the engine control section 105 . Therefore, by comparing the throttle base torque Tt and the estimated torque Te, the estimated torque monitoring unit 104 can make a highly accurate comparison with common conditions of disturbances to the engine 2 such as changes in atmospheric pressure.

Therefore, the estimated torque monitoring section 104 can determine the normality of the estimated torque Te by comparing it with the throttle base torque Tt. For example, the throttle base torque monitoring unit 103 determines that the estimated torque Te is normal when the difference (absolute value) between the throttle base torque Tt and the estimated torque Te is less than a predetermined threshold value Kb.

As a result, the estimated torque Te can be regarded as a parameter that satisfies the ASIL standard in the same manner as the engine demand torque Treq. Therefore, the estimated torque monitoring unit 104 can ensure the reliability of the estimated torque Te by determining that the estimated torque Te is normal.

In this way, the throttle base torque monitoring section 103 and the estimated torque monitoring section 104 can easily secure the reliability of the estimated torque Te by stepwise comparison with the engine demand torque Treq and the throttle base torque Tt.

The operation control unit 100 notifies the vehicle ECU 6 of the estimated torque Te when the estimated torque monitoring unit 104 determines that the estimated torque Te is normal. In this case, the vehicle ECU 6 calculates the motor demand torque Tm from the estimated torque Te. Since the estimated torque Te is a highly reliable and highly accurate parameter, the motor ECU 3 can normally control the torque of the motor 31 based on the motor required torque Tm.

Further, when the estimated torque monitoring unit 104 determines that the estimated torque Te is abnormal, the operation control unit 100 notifies the vehicle ECU 6 that the estimated torque Te is abnormal. In this case, the vehicle ECU 6 stops calculating the motor demand torque Tm using the estimated torque Te. Therefore, the torque control of the motor 31 is prevented from becoming abnormal.

(Monitoring process of estimated torque)
FIG. 3 is a flowchart showing an example of the process of monitoring the estimated torque Te. This process is periodically executed by the engine ECU 1, for example. Note that this process is a method of monitoring the estimated torque Te that is executed by the engine ECU 1 .

First, the operation control unit 100 acquires various parameters (hereinafter referred to as operating state parameters) regarding the operating state of the engine 2 from the sensor system 26 (step St1). Next, the operation control unit 100 determines whether or not to monitor the estimated torque Te based on the operating state parameters (step St2).

For example, the operation control unit 100 determines that the monitoring of the estimated torque Te is unnecessary when a failure such as a motor abnormality or a communication abnormality of the engine ECU 1 is detected from the operational state parameters. When the operation control unit 100 determines that monitoring of the estimated torque Te is unnecessary (No in step 2), the process ends. Further, when the operation control unit 100 determines that monitoring of the estimated torque Te is necessary (Yes in step 2), each process after step St3 below is executed.

The torque estimator 102 acquires the detected value (AFM detected value) of the airflow meter 23 (step St3). Next, the torque estimator 102 calculates the estimated torque Te based on the detected value of the airflow meter 23 (step St4).

Next, the torque estimator 102 acquires the detected value of the throttle opening sensor 25 (step St5). Next, the torque estimator 102 calculates the throttle base torque Tt based on the detected value of the throttle opening sensor 25 (step St6).

Next, the required torque acquisition unit 101 acquires the engine required torque Treq from the vehicle ECU 6 (step St7).

Next, the throttle base torque monitoring unit 103 compares the throttle base torque Tt with the engine demand torque Treq (step St8). If the absolute value of the difference between the throttle base torque Tt and the engine demand torque Treq is equal to or greater than the threshold value Ka (No in step St8), the throttle base torque Tt is determined to be abnormal. Notify (step St11).

When the absolute value of the difference between the throttle base torque Tt and the engine demand torque Treq is less than the threshold value Ka (Yes in step St8), the throttle base torque monitoring unit 103 determines that the throttle base torque Tt is normal. 104 compares the estimated torque Te with the throttle base torque Tt (step St9). When the absolute value of the difference between the estimated torque Te and the throttle base torque Tt is equal to or greater than the threshold Kb (No in step St9), the estimated torque Te is determined to be abnormal, so the operation control unit 100 notifies the vehicle ECU 6 of the abnormality. (Step St11).

When the absolute value of the difference between the estimated torque Te and the throttle base torque Tt is less than the threshold Kb (Yes in step St9), the estimated torque monitoring unit 104 determines that the estimated torque Te is normal. Te is notified to the vehicle ECU 6 (step St10).

In this manner, throttle base torque monitoring unit 103 monitors the normality of throttle base torque Tt by comparing throttle base torque Tt with engine demand torque Treq. The engine demand torque Treq is a parameter that satisfies the ASIL standard. Therefore, the throttle base torque monitoring unit 103 can ensure the reliability of the throttle base torque Tt by judging that the throttle base torque Tt is normal based on the comparison result between the throttle base torque Tt and the engine demand torque Treq.

Further, when the throttle base torque monitoring section 103 confirms the normality of the throttle base torque Tt, the estimated torque monitoring section 104 monitors the normality of the estimated torque Te by comparing the estimated torque Te with the throttle base torque Tt. . The reliability of the throttle base torque Tt is ensured by comparison with the engine demand torque Treq. Therefore, the estimated torque monitoring unit 104 can ensure the reliability of the estimated torque Te by judging that the estimated torque Te is normal based on the comparison result between the estimated torque Te and the throttle base torque Tt.

The embodiments described above are examples of preferred implementations of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

1 Engine ECU (monitoring device)
2 engine (internal combustion engine)
20 Intake passage 23 Air flow meter 24 Throttle valve 25 Throttle opening sensor 103 Throttle base torque monitor (first monitor)
104 estimated torque monitor (second monitor)

Claims (1)

Comparing a first estimated value of the output torque of the internal combustion engine estimated from a detected value of the opening of a throttle valve provided in an intake passage of the internal combustion engine with a requested output torque value of the internal combustion engine. a first monitoring unit that monitors the normality of the first estimated value by
When the first monitoring unit confirms the normality of the first estimated value, the second estimated value of the output torque of the internal combustion engine estimated from the detected value of the intake air amount drawn from the intake passage is a second monitoring unit that monitors the normality of the second estimated value by comparing it with the first estimated value;
The required value is a parameter that satisfies a predetermined criterion for reliability,
surveillance equipment.

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