Monitoring device

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

[Technical field]

[0001] The present invention relates to a monitoring device. [Background technology]

[0002] A hybrid vehicle is provided with an engine (internal combustion engine) and a motor (electric motor) that output torque to drive the vehicle (see, for example, Patent Document 1). The motor is required to have the torque remaining after subtracting an estimated value of the engine's output torque from the torque required in response to the operation of the vehicle driver. Therefore, in order to properly control the motor torque, it is necessary to monitor that the estimated value of the output torque is a highly accurate and reliable value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-111276 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when estimating an output torque from the detected value of the intake air volume of the engine detected by an air flow meter, a highly accurate estimated value can be calculated. In addition, an index of the reliability of the estimated value can be, for example, the Automotive Safety Integrity Level (ASIL) defined in ISO (International Organization for Standardization) 26262.

[0005] However, calculating an estimated output torque from the detection value of a sensor such as an air flow meter requires a large number of parameters and complicated calculation processing, and it may be difficult to satisfy reliability standards such as ASIL.

[0006] Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a monitoring device that can easily ensure the reliability of an estimated value of output torque of an internal combustion engine. [Means for solving the problem]

[0007] The monitoring device of the present invention has a first monitoring unit that monitors the normality of a first estimated value of an output torque of the internal combustion engine, estimated from a detection value of the opening of a throttle valve provided in an intake passage of the internal combustion engine, by comparing the first estimated value with a required value of an output torque required of the internal combustion engine, and a second monitoring unit that, when the first monitoring unit confirms the normality of the first estimated value, monitors the normality of a second estimated value of the output torque of the internal combustion engine, estimated from a detection value of the amount of intake air taken in from the intake passage, by comparing the second estimated value with the first estimated value, wherein the required value is a parameter that satisfies a predetermined standard for reliability. Effect of the Invention

[0008] According to the present invention, the reliability of the estimated value of the output torque of the internal combustion engine can be easily ensured. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram showing an example of a vehicle system. [Diagram 2] FIG. 2 is a configuration diagram showing an example of an engine ECU (Electronic Control Unit). [Diagram 3] 5 is a flowchart showing an example of a monitoring process of an estimated torque. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Vehicle system configuration) 1 is a configuration diagram showing an example of a vehicle system 9. The vehicle system 9 is mounted on, for example, a hybrid vehicle, and includes 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, an axle 52, and wheels 53.

[0011] The accelerator sensor 60 detects the opening degree of an accelerator pedal (not shown), and the brake sensor 61 detects the opening degree of a brake pedal (not shown). The 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 their detection values ​​to the vehicle ECU 6.

[0012] The vehicle ECU 6 calculates the torque required for the hybrid vehicle from the detection values ​​of an accelerator sensor 60, a brake sensor 61, and a vehicle speed sensor 62, and so on.

[0013] The engine system 90 includes an engine ECU 1, an engine 2, an intake passage 20, an exhaust passage 21, an air cleaner 22, an air flow meter 23, a throttle valve 24, and a throttle opening sensor 25. The air cleaner 22 is provided at one end of the intake passage 20 and filters outside air. The outside air flows through the intake passage 20 and is drawn into a combustion chamber of the engine 2. Exhaust gas generated by combustion is discharged from the exhaust passage 21 to the outside of the vehicle through a catalytic converter (not shown) or the like.

[0014] An air flow meter 23 and a throttle valve 24 are provided in the intake passage 20. The air flow meter 23 is located upstream of the throttle valve 24 and detects the amount of intake air in the intake passage 20. The air flow meter 23 outputs a detected value of the amount of intake air to the engine ECU 1.

[0015] The opening of the throttle valve 24 is controlled by the engine ECU 1. The throttle opening sensor 25 detects the opening of the throttle valve 24. The throttle opening sensor 25 outputs a detected value of the opening of the throttle valve 24 to the engine ECU 1.

[0016] The sensor system 26 includes a plurality of 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, and the pressure of each part of the engine 2. The sensor system 26 outputs each detection value to the engine ECU 1.

[0017] The engine ECU 1 controls the operation of the engine 2 based on the detection values ​​of the sensor system 26, the air flow meter 23, and the throttle opening sensor 25. The engine ECU 1 receives a command for the torque required of 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 of the throttle valve 24 so that the output torque of the engine 2 approaches the engine required torque. The engine 2 is an example of an internal combustion engine. The engine required torque Treq is an example of a required value of the output torque required of the engine 2.

[0018] 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. The boost converter 32 boosts the voltage of the battery 33 and applies it to the inverter 30. The inverter 30 converts the DC current input from the boost converter 32 into a three-phase AC current and outputs it to the motor 31. The motor 31 rotates a rotor (not shown) by the three-phase AC current.

[0019] The motor ECU 3 controls the operation of the motor 31. The motor ECU 3 receives a command for torque required of 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 the CAN (Controller Area Network) standard, for example.

[0020] The rotating shafts of the engine 2 and the motor 31 are connected to a differential gear device 50 via a power transmission mechanism (not shown). The differential gear device 50 is connected to an axle 52 that rotates wheels 53. As a result, the hybrid vehicle is driven by the output torques of the engine 2 and the motor 31.

[0021] The vehicle ECU 6 determines the distribution of output torque between the engine 2 and the motor 31. The vehicle system 9 first calculates an engine required torque Treq from the detection values ​​of the accelerator sensor 60, the brake sensor 61, and the vehicle speed sensor 62, and issues a command to the engine ECU 1. The engine required torque Treq is a highly reliable parameter that satisfies, for example, the ASIL.

[0022] That is, the engine required torque Treq is calculated based on a highly reliable design defined by ISO 26262. For this reason, the vehicle ECU 6 that calculates the engine required torque Treq uses, for example, a memory and a power supply circuit with a low failure rate, and also has memory redundancy and a communication error correction function implemented therein.

[0023] This reduces the likelihood that the engine demand torque Treq will become an abnormal value (error value) due to component failure, etc., compared to other parameters that do not meet the ASIL standard. Conversely, since the engine demand torque Treq meets the ASIL standard, it is more likely to become a normal value than other parameters that do not meet the ASIL standard. Note that ASIL is an example of a predetermined standard regarding reliability.

[0024] The engine ECU 1 controls the engine 2 in accordance with the engine required 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).

[0025] Tm = Tvh - Te (1)

[0026] The vehicle ECU 6 calculates the motor torque requirement Tm from the estimated torque Te. In equation (1), Tvh is the torque required in response to the operation of the driver of the hybrid vehicle (hereinafter referred to as vehicle torque).

[0027] In this way, the motor 31 is required to have the remaining required torque Tm, which is the vehicle torque Tvh minus the estimated torque Te. Therefore, the engine ECU 1 monitors the normality of the estimated torque Te so that the motor ECU 3 appropriately controls the torque of the motor 31. The engine ECU 1 is an example of a monitoring device.

[0028] (Engine ECU configuration) 2 is a configuration diagram showing an example of the engine ECU 1. 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 the ROM 11, the RAM 12, and the input / output port 13 via a bus 19 so as to be able to input and output signals between them.

[0029] The ROM 11 stores a program that drives the CPU 10. The RAM 12 functions as a working memory for the CPU 10. The input / output port 13 relays communications between the CPU 10 and the vehicle ECU 6, the sensor system 26, the air flow meter 23, the throttle valve 24, and the throttle opening sensor 25.

[0030] When the CPU 10 reads the program from the ROM 11, it forms, as functions, an operation control unit 100, a required torque obtaining unit 101, a torque estimation unit 102, a throttle-based torque monitoring unit 103, an estimated torque monitoring unit 104, and an engine control unit 105. The operation control unit 100 instructs the required torque obtaining unit 101, the torque estimation unit 102, the throttle-based torque monitoring unit 103, the estimated torque monitoring unit 104, and the engine control unit 105 to perform various processes in accordance with a sequence defined in the program. In addition, the operation control unit 100 inputs and outputs parameters required for each process between the required torque obtaining unit 101, the torque estimation unit 102, the throttle-based torque monitoring unit 103, the estimated torque monitoring unit 104, and the engine control unit 105.

[0031] The required torque obtaining unit 101 obtains the engine required torque Treq from the vehicle ECU 6 via the input / output port 13 .

[0032] The torque estimation unit 102 estimates the output torque of the engine 2. The torque estimation unit 102 calculates an estimate of the output torque of the engine 2 (hereinafter, referred to as throttle base torque Tt) in accordance with a predetermined calculation formula based on the detection value of the throttle opening sensor 25, the detection values ​​of the pressures and temperatures upstream and downstream of the throttle valve 24, and the ignition timing of the spark plugs of the engine 2. The throttle base torque Tt is an example of a first estimate of the output torque of the engine 2 estimated from the detection value of the opening of the throttle valve 24.

[0033] Furthermore, the torque estimation unit 102 calculates the estimated torque Te according to a predetermined calculation formula based on the detection value of the air flow meter 23, the ignition timing of the spark plug of the engine 2, etc. The estimated torque Te is an example of a second estimated value of the output torque of the engine 2 estimated from the detection value of the amount of intake air taken in from the intake passage 20.

[0034] The detection value of the air flow meter 23 is the amount of intake air from the intake passage 20 to the engine 2, and therefore has a stronger correlation with the output torque of the engine 2 than the opening degree 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 higher accuracy. Therefore, the vehicle ECU 6 calculates the motor required torque Tm from the estimated torque Te using the above formula (1).

[0035] The engine control unit 105 controls the opening of the throttle valve 24, the amount of fuel injected into the engine 2, the ignition timing of the engine 2, etc., based on the engine required torque Treq. At this time, the detection value of the air flow 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 required torque Treq as a response to the control of the engine control unit 105.

[0036] Although the throttle base torque Tt and the estimated torque Te are more accurate than the engine required torque Treq, they do not meet the ASIL standard and are therefore less reliable than the engine required torque Treq, which meets the ASIL standard.The throttle base torque Tt and the estimated torque Te require a large number of parameters and complicated calculation processing, making it difficult for them to meet the ASIL standard.

[0037] Therefore, the engine ECU 1 ensures the reliability of the estimated torque Te by making a step-by-step comparison as follows.

[0038] 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 required torque Treq. Here, the engine required torque Treq is a highly reliable parameter that satisfies the ASIL standard.

[0039] Furthermore, when the engine ECU 1 is normal, the opening degree of the throttle valve 24 is controlled by the engine control unit 105 based on the engine required torque Treq. For this reason, the engine required torque Treq has a stronger correlation with the throttle base torque Tt than with the estimated torque Te.

[0040] Therefore, the throttle base torque monitoring unit 103 can determine the normality of the throttle base torque Tt by comparing it with the engine required 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 required torque Treq is less than a predetermined threshold value Ka.

[0041] This allows the throttle base torque Tt to be regarded as a parameter that satisfies the ASIL standard, similar to the engine required 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.

[0042] The estimated torque monitoring unit 104 is an example of a second monitoring unit, and when the throttle base torque monitoring unit 103 determines that the throttle base torque Tt is normal, the estimated torque monitoring unit 104 monitors the normality of the estimated torque Te by comparing the estimated torque Te with the throttle base torque Tt. 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 guaranteed by comparison with the engine required torque Treq that satisfies the ASIL standard.

[0043] Furthermore, the throttle base torque Tt and the estimated torque Te are responses to the control of the engine control unit 105. Therefore, the estimated torque monitoring unit 104 can perform a highly accurate comparison by comparing the throttle base torque Tt and the estimated torque Te, while standardizing the conditions of disturbances to the engine 2, such as changes in atmospheric pressure.

[0044] Therefore, the estimated torque monitoring unit 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.

[0045] This allows the estimated torque Te to be regarded as a parameter that satisfies the ASIL standard, similar to the engine required 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.

[0046] In this way, the throttle base torque monitoring section 103 and the estimated torque monitoring section 104 can easily ensure the reliability of the estimated torque Te by stepwise comparison with the engine required torque Treq and the throttle base torque Tt.

[0047] When the estimated torque monitoring unit 104 determines that the estimated torque Te is normal, the operation control unit 100 notifies the vehicle ECU 6 of the estimated torque Te. In this case, the vehicle ECU 6 calculates the motor required torque Tm from the estimated torque Te. Since the estimated torque Te is a highly reliable and accurate parameter, the motor ECU 3 can normally control the torque of the motor 31 based on the motor required torque Tm.

[0048] Furthermore, 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 of the abnormality in the estimated torque Te. In this case, the vehicle ECU 6 stops calculating the motor required torque Tm using the estimated torque Te. This prevents the torque control of the motor 31 from becoming abnormal.

[0049] (Monitoring process of estimated torque) 3 is a flowchart showing an example of a process for monitoring the estimated torque Te. This process is periodically executed by, for example, the engine ECU 1. Note that this process is a method for monitoring the estimated torque Te executed by the engine ECU 1.

[0050] First, the operation control unit 100 acquires various parameters (hereinafter referred to as operating state parameters) related to the operating state of the engine 2 from the sensor system 26 (step St1). Next, the operation control unit 100 determines whether or not it is necessary to monitor the estimated torque Te from the operating state parameters (step St2).

[0051] For example, when the operation control unit 100 detects a fault such as a motor abnormality or a communication abnormality of the engine ECU 1 from the operation state parameters, it determines that it is not necessary to monitor the estimated torque Te. When the operation control unit 100 determines that it is not necessary to monitor the estimated torque Te (No in step 2), it ends the process. When the operation control unit 100 determines that it is necessary to monitor the estimated torque Te (Yes in step 2), the following processes from step St3 onwards are executed.

[0052] The torque estimation unit 102 acquires the detection value (AFM detection value) of the air flow meter 23 (step St3). Next, the torque estimation unit 102 calculates the estimated torque Te based on the detection value of the air flow meter 23 and the like (step St4).

[0053] Next, the torque estimation unit 102 acquires the detection value of the throttle opening sensor 25 (step St5). Next, the torque estimation unit 102 calculates the throttle base torque Tt based on the detection value of the throttle opening sensor 25 and the like (step St6).

[0054] Next, the required torque obtaining unit 101 obtains the engine required torque Treq from the vehicle ECU 6 (step St7).

[0055] Next, the throttle base torque monitoring unit 103 compares the throttle base torque Tt with the engine required torque Treq (step St8). If the absolute value of the difference between the throttle base torque Tt and the engine required 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, and the operation control unit 100 notifies the vehicle ECU 6 of the abnormality (step St11).

[0056] If the absolute value of the difference between the throttle base torque Tt and the engine required 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, so the estimated torque monitoring unit 104 compares the estimated torque Te with the throttle base torque Tt (step St9). If 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 value 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).

[0057] If the absolute value of the difference between the estimated torque Te and the throttle base torque Tt is less than the threshold value Kb (Yes in step St9), the estimated torque monitoring unit 104 determines that the estimated torque Te is normal, and the operation control unit 100 notifies the vehicle ECU 6 of the estimated torque Te (step St10).

[0058] In this way, the throttle base torque monitoring unit 103 monitors the normality of the throttle base torque Tt by comparing the throttle base torque Tt with the engine required torque Treq. The engine required 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 determining that the throttle base torque Tt is normal based on the comparison result between the throttle base torque Tt and the engine required torque Treq.

[0059] Furthermore, when the throttle base torque monitoring unit 103 confirms the normality of the throttle base torque Tt, the estimated torque monitoring unit 104 compares the estimated torque Te with the throttle base torque Tt to monitor the normality of the estimated torque Te. The reliability of the throttle base torque Tt is guaranteed by the comparison result with the engine required torque Treq. Therefore, the estimated torque monitoring unit 104 can guarantee the reliability of the estimated torque Te by determining that the estimated torque Te is normal based on the comparison result between the estimated torque Te and the throttle base torque Tt.

[0060] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this embodiment and can be modified in various ways without departing from the scope of the present invention. [Explanation of symbols]

[0061] 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 monitoring unit (first monitoring unit) 104 Estimated torque monitoring unit (second monitoring unit)

Claims

[Claim 1] a first monitoring unit that monitors normality of a first estimated value of an output torque of the internal combustion engine by comparing the first estimated value with a required value of an output torque required for the internal combustion engine, the first estimated value being estimated from a detection value of an opening degree of a throttle valve provided in an intake passage of the internal combustion engine; a second monitoring unit that, when the first monitoring unit confirms the normality of the first estimated value, monitors the normality of the second estimated value by comparing a second estimated value of an output torque of the internal combustion engine estimated from a detection value of an amount of intake air taken in through the intake passage with the first estimated value, The required value is a parameter that satisfies a predetermined criterion regarding reliability. monitoring equipment.

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