Internal combustion engine control device

Abstract

The ECU includes a processing device that repeatedly executes an air amount operation process that estimates a flow rate of intake air. The processing device acquires a detection value of the flow rate sensor and stores it in a storage device, stores a time when the detection value of the flow rate sensor is acquired as a first time stamp in the storage device, and stores a time when the air amount operation process is executed as a second time stamp in the storage device. The air amount operation process of the processing device calculates an execution interval of the operation process at a current time point based on the second time stamp, sets an accumulation period of a time width that is the same as the execution interval of the operation process at the current time point based on the second time stamp, calculates a cumulative mass of the intake air in the accumulation period based on the detection value of the flow rate sensor and the first time stamp, and estimates the flow rate of the intake air in the accumulation period using the cumulative mass of the operation result and the execution interval.

Description

Technical Field

[0001] This invention relates to an internal combustion engine control device for controlling an internal combustion engine, and more specifically, to an internal combustion engine control device for controlling fuel injection of an internal combustion engine based on a detection signal from a flow sensor that detects the amount of air intake into the internal combustion engine. Background Technology

[0002] In recent years, fuel consumption rates and emissions restrictions have been strengthened in automobiles and other vehicles powered by internal combustion engines, and these restrictions are likely to become increasingly stringent in the future. The flow rate of air drawn into the internal combustion engine (hereinafter sometimes referred to as intake air volume) is a parameter used by the internal combustion engine control unit (hereinafter sometimes referred to as ECU (Engine Control Unit)) when calculating the fuel injection quantity of the internal combustion engine. Therefore, in order to cope with future restrictions, it is important to accurately predict the constantly changing intake air volume.

[0003] An example of a sensor for detecting the amount of air intake can be cited as an airflow sensor. Types of airflow sensors include, for example, hot-wire sensors with a heating resistor. The detection signal of this type of airflow sensor mostly uses a voltage signal whose voltage value changes based on a signal from the heating resistor, or a frequency signal whose output pulse period changes based on a signal from the heating resistor, which varies according to the amount of air intake. It is known that airflow sensors incorporate sensors for detecting pressure, humidity, etc. In such airflow sensors, SENT (Single Edge Nibble Transmission) communication is increasingly used. SENT communication uses a single signal line to transmit detection values ​​from multiple sensors. The transmission cycle of SENT communication is managed approximately constantly within the airflow sensor. SENT communication is a unidirectional communication from the airflow sensor to the ECU, transmitting sensor values ​​at a phase different from the ECU's operating cycle.

[0004] As a technique for calculating the intake air volume of an internal combustion engine, the technique described in Patent Document 1 is known, for example. In the internal combustion engine control device described in Patent Document 1, the intake air volume (cumulative mass of intake air) is calculated based on the actual sensor value measured by the airflow sensor and the time at which the sensor value is acquired, within a predetermined cumulative period with the same time width corresponding to a predetermined calculation period that is longer than the acquisition period of the airflow sensor value. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-159369 Summary of the Invention The technical problem that the invention aims to solve

[0006] In the internal combustion engine control device described in Patent Document 1, the time width of the calculation cycle for the intake air volume is set to a predetermined value (e.g., 2 ms) that is longer than the acquisition period of the airflow sensor value (e.g., 0.95 ms), and the aforementioned accumulation period has the same time width as the calculation cycle for the intake air volume. This internal combustion engine control device converts the intake air volume (cumulative mass of intake air) during the accumulation period of the calculation result into the average intake air flow rate (mass flow rate) per unit time by dividing the predetermined time width of the accumulation period (the same predetermined time width as the calculation cycle), and uses the converted result to calculate the fuel injection quantity. However, the calculation cycle (time width) for the intake air volume may vary due to its relationship with other calculation processes or interruptions in the calculation process.

[0007] However, Patent Document 1 does not describe the impact of variations in the calculation period's time width on the calculation results. However, when converting the cumulative mass of intake air over a cumulative period into the average intake air flow rate (mass flow rate) per unit time, the effect arises when the calculation period's time width for the intake air volume changes beyond a predetermined value. That is, the calculated result for the average intake air flow rate varies depending on the time width of the calculation period. Consequently, this also affects the fuel injection quantity calculated using the average intake air flow rate, potentially degrading exhaust performance.

[0008] The present invention was made to solve the above-mentioned problems, and its purpose is to provide an internal combustion engine control device that can accurately predict the intake air volume even if the execution interval of the calculation and processing of the intake air volume of the internal combustion engine varies. Technical means for solving technical problems

[0009] This application includes several methods for solving the above-mentioned problems. For example, in an internal combustion engine control device comprising a processing apparatus that repeatedly executes an air volume calculation process based on the detection value of a flow sensor that detects the intake air flow rate of an internal combustion engine at time intervals to estimate the intake air flow rate, and a storage device that stores information required for the air volume calculation process of the processing apparatus, the processing apparatus is configured to acquire the detection value of the flow sensor at a predetermined acquisition period shorter than the execution interval of the air volume calculation process and store it in the storage device; the time when the detection value of the flow sensor is acquired is stored in the storage device as a first timestamp corresponding to the detection value of the flow sensor; and the time when the air volume calculation process is executed each time is stored as a second timestamp. The timestamp is stored in the storage device. In each air volume calculation process of the processing device, an execution interval calculation is performed based on the second timestamp stored in the storage device to calculate the execution interval of the calculation process at the current time point. Based on the second timestamp stored in the storage device, a cumulative period with the same time width as the execution interval of the calculation process at the current time point is set. Based on the detection value of the flow sensor stored in the storage device and its corresponding first timestamp, a cumulative calculation is performed to calculate the cumulative mass of the inhaled air within the set cumulative period. Based on the calculation result of the cumulative calculation and the calculation result of the execution interval calculation, a predicted flow rate calculation is performed to estimate the flow rate of the inhaled air within the set cumulative period. Invention Effects

[0010] According to the present invention, since the execution interval of each air volume calculation process is calculated based on the second timestamp stored in the storage device, and the flow rate of the intake air is estimated using the execution interval of the calculation result, even if the execution interval of the air volume calculation process is not a fixed period but varies, the influence of the variation of the execution interval of the air volume calculation process on the estimated flow rate of the calculation result can be eliminated. That is, even if the execution interval of the air volume calculation process of the processing device varies, the intake air volume can be estimated with high accuracy. The problems, structures, and effects other than those mentioned above will become clearer through the following description of the implementation methods. Attached Figure Description

[0011] Figure 1 This is a simplified structural diagram of an internal combustion engine system that includes an internal combustion engine control device according to one embodiment of the present invention. Figure 2 It means Figure 1 The diagram shown is a block diagram illustrating the function of an internal combustion engine control device according to one embodiment of the present invention. Figure 3 It means Figure 2The diagram illustrates the reason for the variation in the execution interval of each air quantity calculation process in an internal combustion engine control device according to one embodiment of the present invention. Figure 4 It means Figure 2 The figure shows an example of the variation in the execution interval of air quantity calculation processing in an internal combustion engine control device according to an embodiment of the present invention. Figure 5 It is Figure 2 The illustration shows the relationship between the execution interval of the calculation process, the cumulative period set in the calculation process, and the transmission cycle of the sensor in the air quantity calculation process of the internal combustion engine control device according to one embodiment of the present invention, together with the timer count (elapsed time). Figure 6 It means Figure 2 The illustration shows an example of a method for calculating the cumulative mass of intake air in the cumulative air mass calculation unit of an internal combustion engine control device according to an embodiment of the present invention. Figure 7 It means Figure 2 The flowchart shown is an example of a processing step involving air quantity calculation processing in an internal combustion engine control device according to an embodiment of the present invention. Detailed Implementation

[0012] Hereinafter, embodiments of the internal combustion engine control device of the present invention will be described using the accompanying drawings. In this embodiment, a reciprocating engine will be used as an example of the controlled object of the internal combustion engine control device.

[0013] First, use Figure 1 This describes a brief structure of an internal combustion engine system that includes an internal combustion engine control device according to one embodiment of the present invention. Figure 1 This is a simplified structural diagram of an internal combustion engine system that includes an internal combustion engine control device according to one embodiment of the present invention.

[0014] exist Figure 1 In this internal combustion engine system, there is an internal combustion engine 1 (hereinafter sometimes referred to as an engine) and an ECU (Engine Control Unit) 60, which is an internal combustion engine control device for controlling the internal combustion engine 1. The engine 1 is, for example, a spark-ignition reciprocating engine mounted as a prime mover in a automobile. The engine 1 includes an engine body 2, which has a cylinder block 3 and a cylinder head 4. Multiple cylinders are formed in the engine body 2. Figure 1(Only one is shown in the diagram) Pneumatic actuator 2a (cylinder). A piston 6 is slidably inserted into each pneumatic actuator 2a. The piston 6 is connected to a crankshaft (not shown) via a connecting rod 7. The crankshaft converts the reciprocating motion of the piston 6 into rotational motion. An intake valve 9 and an exhaust valve 10 are disposed on the cylinder head 4. The intake valve 9 and the exhaust valve 10 are opened and closed by the intake camshaft 11 and the exhaust camshaft 12, respectively.

[0015] The combustion chamber 14 is formed by the cylinder block 3, cylinder head 4, piston 6, intake valve 9, and exhaust valve 10. On the cylinder head 4, spark plugs 16 are provided corresponding to the combustion chambers 14 of each cylinder 2a. The spark plugs 16 are electrically connected to the ignition coil 17, and a high-voltage ignition signal is supplied from the ignition coil 17.

[0016] On the intake valve 9 side of the engine body 2, the intake passage 20 is communicatively connected to the combustion chamber 14. The intake passage 20 includes an air filter 21 and an intake manifold 22 with a collector 23, and has an intake port 20a at its downstream end. The air filter 21 filters the air drawn into the engine 1. The intake manifold 22 is connected to each cylinder 2a of the engine body 2, causing the drawn-in air to be distributed from the collector 23 to each cylinder 2a. Upstream of the collector 23 in the intake passage 20, a throttle valve 24 is provided to regulate the flow rate of the drawn-in air.

[0017] An exhaust passage 30 is connected to the exhaust valve 10 side of the engine body 2. The exhaust passage 30 includes an exhaust manifold 31, with an exhaust port 30a at its upstream end. A three-way catalyst 32 is disposed downstream of the exhaust manifold 31 in the exhaust passage 30. The three-way catalyst 32 is a catalyst for exhaust gas purification coated with platinum or palladium on a carrier such as alumina or cerium oxide, for purifying exhaust gas.

[0018] On the intake manifold 22 of the intake passage 20, a fuel injection valve 41 is provided corresponding to each cylinder 2a. The fuel injection valve 41 is configured to inject fuel into the intake port 20a of the intake passage 20. The fuel injection valve 41 is opened and driven according to a control signal (fuel injection signal) from the ECU 60. Fuel is supplied to the fuel injection valve 41 through a fuel supply mechanism. The fuel supply mechanism includes: a fuel tank 42 for storing fuel; a fuel pump 43 for delivering fuel from the fuel tank 42 to the fuel injection valve 41; and a fuel regulator 44 for adjusting the pressure of the fuel supplied to the fuel injection valve 41. Alternatively, the fuel injection valve 41 can also be configured as a direct-injection type that injects fuel directly into the pneumatic actuator 2a.

[0019] Downstream of the air filter 21 and upstream of the throttle valve 24 in the intake passage 20, an airflow sensor 51 is provided as an example of a flow sensor for detecting the intake air flow rate. The airflow sensor 51, for example, has a hot wire (thermal resistor) disposed within the intake passage 20. A bridging circuit is formed in the airflow sensor 51 such that the current flowing through the hot wire increases as the intake air flow rate increases, and decreases as the flow rate decreases. The airflow sensor 51 extracts the current value of the thermal resistor flowing through the hot wire (the value corresponding to the intake air flow rate) as a voltage signal and outputs the sensor value (e.g., voltage, frequency signal, or SENT communication data) to the ECU 60. In the case of SENT communication, the airflow sensor 51 sends the sensor value corresponding to the intake air flow rate to the ECU 60 according to each predetermined transmission cycle. For example, according to the SAE standard (SAE-J2716), the transmission cycle is 1 ms.

[0020] An air-fuel ratio sensor 52 is disposed upstream of the three-way catalytic converter 32 in the exhaust passage 30. The air-fuel ratio sensor 52 has, for example, a linear output characteristic relative to the air-fuel ratio of the exhaust flowing upstream of the three-way catalytic converter 32. An O2 sensor 53 is disposed downstream of the three-way catalytic converter 32 in the exhaust passage 30. The O2 sensor 53 outputs, for example, a switching signal to the ECU 60 to identify whether the air-fuel ratio of the exhaust flowing downstream of the three-way catalytic converter 32 is rich or lean compared to the stoichiometric ratio (stoichiometric air-fuel ratio).

[0021] The internal combustion engine system includes a throttle opening sensor 54 that detects the throttle opening of the accelerator pedal 19. The throttle opening sensor 54 outputs a throttle opening signal corresponding to the detected throttle opening to the ECU 60.

[0022] ECU 60 is an electronic control device that manages all controls of engine 1 based on various information. For example, based on throttle opening signals from throttle opening sensor 54, ECU 60 performs processes such as controlling the amount of fuel injected from fuel injection valve 41 (air-fuel ratio control processing) and controlling the ignition timing of spark plug 16. Furthermore, in this embodiment, ECU 60 performs calculations on the amount of intake air based on sensor values ​​(intake air flow) from airflow sensor 51. ECU 60 includes a microcomputer containing ROM 61 (Read Only Memory) and RAM 62 as storage devices, MPU 63 (Micro Processor Unit) as a processing device, driver 64, etc. ROM 61, RAM 62, and MPU 63 are connected via bus 65. Additionally, ECU 60 has a built-in timer function that continuously counts.

[0023] ROM 61 stores various programs for controlling the engine 1. MPU 63 performs various calculations based on the programs read from ROM 61. RAM 62 temporarily stores various information (data) required for the calculations of MPU 63. Driver 64 generates various control signals such as fuel injection command signals for manipulating fuel injection quantity and ignition timing command signals for manipulating ignition timing based on the calculation results of MPU 63, and outputs the generated control signals to various devices such as fuel injection valve 41 and ignition coil 17. In this embodiment, the MPU 63 of ECU 60 repeatedly executes air volume calculation processing based on the sensor value of airflow sensor 51 to estimate the intake air flow of engine 1 according to the program stored in ROM 61 at time intervals, and controls the fuel injection quantity based on the calculation result of air volume calculation processing (estimated intake air flow).

[0024] In the internal combustion engine system described above, air drawn in through the intake port (not shown) (intake air) passes through the air filter 21, and its flow rate is adjusted by the throttle valve 24 before flowing into the collector 23 of the intake manifold 22. The intake air flowing into the collector 23 flows through the branch pipes of the intake manifold 22 to the intake port 20a corresponding to each cylinder 2a.

[0025] The fuel stored in the fuel tank 42 is adjusted to a specified pressure by the fuel pump 43 and the fuel regulator 44 and supplied to the fuel injection valve 41. The fuel supplied to the fuel injection valve 41 is injected into the intake port 20a corresponding to each cylinder 2a by opening the fuel injection valve 41, which corresponds to the control signal from the ECU 60.

[0026] Air intake through intake port 20a of intake passage 20 and fuel injected into intake port 20a from fuel injection valve 41 are mixed to generate a mixture. This mixture is drawn into combustion chamber 14 of each cylinder 2a as intake valve 9 opens. The mixture in combustion chamber 14 is compressed by piston 6 and ignited by spark plug 16 generated by the application of high voltage to ignition coil 17 corresponding to a control signal from ECU 60. The combustion of the mixture drives a crankshaft (not shown) via piston 6 rotation.

[0027] The exhaust gases generated by combustion are discharged from the combustion chamber 14 through the exhaust port 30a of the exhaust passage 30 to the exhaust manifold 31 as the exhaust valve 10 is opened, and are then guided to the three-way catalyst 32 for purification. The exhaust gases passing through the three-way catalyst 32 are finally released into the atmosphere through the exhaust passage 30.

[0028] Next, use Figures 2-6 This invention describes the functional structure of an ECU according to one embodiment of the present invention. Figure 2 It means Figure 1 The diagram shown is a block diagram illustrating the function of an internal combustion engine control device according to one embodiment of the present invention.

[0029] exist Figure 2 In this context, the MPU63 (see reference) estimates the flow rate of air (intake air) drawn into the combustion chamber 14 of the engine 1 based on the detected value (sensor value) of the airflow sensor 51, and controls the fuel injection quantity of the fuel injection valve 41 based on the estimated flow rate of the intake air calculated from the result. Figure 1 The ECU 60 includes functional units such as a sensor value acquisition unit 71, a first timestamp processing unit 72, an execution mark processing unit 73, a second timestamp processing unit 74, an air volume calculation execution interval calculation unit 75, a cumulative period setting unit 76, a cumulative air quality calculation unit 77, an air flow estimation unit 78, and a fuel injection control unit 79. In the ECU 60 of this embodiment, the series of processes up to functional units 74 to 78 of functional units 71 to 79 is equivalent to air volume calculation processing that estimates the intake air flow based on the detection value (sensor value) of the airflow sensor 51. In addition, a part of the calculation processing of the fuel injection control unit 79 is equivalent to fuel injection quantity calculation processing (air-fuel ratio control processing). In addition, the calculation processing of ignition timing will not be described here.

[0030] The sensor value acquisition unit 71 acquires a detection signal corresponding to the amount of intake air (flow rate of intake air) detected by the airflow sensor 51. When the airflow sensor 51 sends a detection signal at a certain period (e.g., 1ms) via SENT communication, the sensor value acquisition unit 71 receives the detection signal from the airflow sensor 51 at a certain period (a certain time interval).

[0031] The first timestamp processing unit 72 stores the count of the timer function when the sensor value acquisition unit 71 receives the detection signal from the airflow sensor 51 as a first timestamp in the storage device (ROM 61 or RAM 62). The first timestamp is stored, for example, corresponding to the received detection value (sensor value) of the airflow sensor 51.

[0032] The execution flag processing unit 73 activates the execution flag indicating the execution of the air quantity calculation process according to the execution instruction of the calculation process. In addition to the air quantity calculation process, the ECU 60 also assigns various calculation processes, such as fuel injection quantity calculation and ignition timing calculation, to various calculation JOBs for execution. The execution instructions for each calculation JOB are managed by the timer function of the ECU 60, and each calculation JOB executes at a certain period according to the execution instruction. In the ECU 60 of this embodiment, for example, the air quantity calculation process is assigned to a 2ms JOB. For the 2ms JOB, in addition to the air quantity calculation process, multiple different processes, such as process A and process B, are also assigned. The execution order of the multiple processes assigned to the 2ms JOB is predetermined. For example, consider the case where process A is executed first, followed by process B, and then the air quantity calculation process. The execution instruction for the 2ms JOB is output at a certain period (time interval) of 2ms. When the instruction for the 2ms JOB is executed, the execution of the air quantity calculation process begins after the execution of process A and process B has ended. Therefore, the execution mark processing unit 73 activates the execution mark indicating the execution of the air volume calculation process and delivers it to the second timestamp processing unit 74.

[0033] When the second timestamp processing unit 74 receives an execution flag that has risen due to the execution of the air volume calculation, it counts the timer function T2 at the time the execution flag was received. p The second timestamp is stored in the storage device (ROM 61 or RAM 62). That is, the second timestamp processing unit 74 stores the time of each execution time point of the air volume calculation process as the second timestamp. When storing the second timestamp of the current execution time point (this time) of the air volume calculation process, the second timestamp processing unit 74 stores at least the second timestamp T2 representing the time of the previous execution time point stored in the previous air volume calculation process. p-1 The information is also pre-stored in the storage device (ROM61 or RAM62). That is, the second timestamp processing unit 74 causes the storage device (ROM61 or RAM62) to pre-store the second timestamp T2 of the last air volume calculation process. p-1 And the second timestamp T2 of this air volume calculation and processing. p Both of these.

[0034] The air volume calculation execution interval calculation unit 75 calculates the execution interval (time width) ΔT for each air volume calculation process. I Specifically, the second timestamp T2 for this event is retrieved from the storage device (ROM61 or RAM62). p And the previous second timestamp T2 p-1 Calculate from the second timestamp T2 of this time p Subtract the previous second timestamp T2p-1 The difference is then calculated. The air volume calculation execution interval calculation unit 75 calculates the execution interval (time width) ΔT of the current air volume calculation. I Transferred to the airflow prediction department 78.

[0035] To improve the accuracy of the calculation results of the airflow estimation unit 78 (described later), a correct execution interval (time width) is required for each airflow calculation process. This airflow calculation process is assigned to a 2ms JOB, but the execution interval is not limited to a constant 2ms. Rather, processing at a constant 2ms time interval is relatively rare, so the execution interval (time width) of the airflow calculation process needs to be pre-calculated each time.

[0036] Figure 3 It means Figure 2 The diagram illustrates the reason for the variation in the execution interval of the air quantity calculation process in an internal combustion engine control device according to one embodiment of the present invention. A 2ms JOB assigned to the air quantity calculation process is executed at a constant period of 2ms via the timer function of the ECU 60. Multiple processes are assigned to the 2ms JOB. The execution order of the 2ms JOB is, for example, process A, process B, and air quantity calculation process. When process A and process B each end with the same processing time, and the air quantity calculation process is executed immediately afterward, the execution interval of the air quantity calculation process is 2ms. However, sometimes a high-priority interruption process Z is executed midway through a 2ms JOB. In this case, the time interval from the execution time of the previous air quantity calculation process to the execution time of the current air quantity calculation process is extended by the amount of the interruption process Z, exceeding 2ms. When there is no interruption process Z in the next executed 2ms JOB, since the execution time of the previous air quantity calculation process is shifted backward compared to the case without interruption process Z, the corresponding time interval until the execution of the next air quantity calculation process becomes shorter, less than 2ms. Furthermore, the processing time for either process A or process B is not limited to the same time width each time. Even if interrupt process Z is not entered in the next 2ms JOB, for example, if the processing time of process B becomes longer, the time interval (execution interval) of the air volume calculation process will change and become longer than 2ms.

[0037] Figure 4 It means Figure 2The diagram illustrates an example of the variation in the execution interval of air quantity calculation processing in an internal combustion engine control device according to an embodiment of the present invention. When the time allocated to each process in a 2ms JOB remains constant and no interruption occurs, the execution interval (time width) of the air quantity calculation processing is the same as the JOB period of the 2ms JOB, which is 2ms. However, as described above, due to variations in the time of each process or the occurrence of an interruption, the execution interval (time width) of the air quantity calculation processing varies as follows: Figure 4 As shown, the interval varies by approximately ±0.5ms, centered around 2ms. Furthermore, if the execution interval of this air volume calculation is extended to around 2.5ms, the execution interval of the next execution will shorten to around 1.5ms. This indicates that a usage... Figure 3 The phenomenon described.

[0038] Thus, the execution interval (time width) of the air volume calculation process of ECU60 may sometimes vary. Therefore, the air volume calculation execution interval calculation unit 75 of ECU60 according to this embodiment calculates the execution interval (time width) ΔT for each air volume calculation process each time the calculation process is performed. I .

[0039] The cumulative period setting unit 76 sets the cumulative period in the cumulative calculation of the cumulative air quality calculation unit 77 (described later). Specifically, the cumulative period (integration interval) for each cumulative calculation of the cumulative air quality calculation unit 77 (described later) is set to have the same time width as the execution interval of each air volume calculation process. This is to prevent repetition or leakage periods from occurring during the cumulative period in repeatedly executed air volume calculation processes. However, this cumulative period (integration interval) is set to be offset by only an offset Tx from the execution time of the air volume calculation process to the past time. That is, the start time T3s of the current cumulative period is the second timestamp T2 from the time representing the execution time of the previous air volume calculation process. p-1 The time is calculated by subtracting the offset Tx. Additionally, the end time T3e of this cumulative period is the second timestamp T2, representing the execution time of this air volume calculation process. p The time is calculated by subtracting the offset Tx. That is, the start time T3s and end time T3e of this cumulative period are calculated according to the following formulas (1) and (2), respectively. T3s=T2 p-1 -Tx…Formula (1) T3e=T2 p -Tx…Equation (2)

[0040] This method of setting the cumulative period is based on the following reasons.

[0041] Since the air volume calculation process is assigned to a 2ms JOB, the execution interval (time width) of this calculation process is approximately 2ms. However, the aforementioned variation occurs within this execution interval of the air volume calculation process. On the other hand, since the sensor value of the airflow sensor 51 is transmitted via SENT communication, the transmission period of this sensor value is, for example, constant at 1ms. Therefore, the ECU 60 receives the sensor value of the airflow sensor 51 essentially twice between each execution time point of the air volume calculation process.

[0042] However, the transmission period of the airflow sensor 51 differs from the execution interval (cycle) of the air volume calculation process of the ECU 60, and the receiving time of the sensor value from the airflow sensor 51 deviates from the execution time of the air volume calculation process. That is, the sensor value of the airflow sensor 51 at the execution time of the air volume calculation process is unknown. Therefore, if the current execution time of the air volume calculation process is set as the end time of the accumulation period, the sensor value of the airflow sensor 51 (intake air flow rate) cannot be used to interpolate the intake air flow rate at the end time of the accumulation period.

[0043] Therefore, as described above, by offsetting the start time T3s and end time T3e of the current accumulation period from the execution time of the air volume calculation process by only an offset Tx, the flow rate of the intake air at the end time T3e of the accumulation period can be interpolated using the sensor value (flow rate of intake air) of the airflow sensor 51. The accumulation period setting unit 76 stores the start time T3s and end time T3e of the current accumulation period of the air volume calculation process as a third timestamp in the storage device (ROM 61 or RAM 62).

[0044] Figure 5 It is Figure 2 The illustration shows the relationship between the execution interval of the calculation process, the cumulative period set in the calculation process, and the transmission cycle of the sensor in the air quantity calculation process of the internal combustion engine control device according to an embodiment of the present invention, together with the timer count (the elapsed time). Figure 5 The vertical axis of the graph below represents the counting function of the timer, which gradually increases over time.

[0045] exist Figure 5 In this process, the sensor value of the airflow sensor 51 is marked with 0 and is received by the ECU 60 every 1ms during the transmission cycle of SENT communication. Therefore, the counts T1a, T1b, T1c, and T1d of the timer function, which indicate the time when the ECU 60 receives the data, are stored as first timestamps in the storage device (ROM 61 or RAM 62).

[0046] Additionally, the timer function, which indicates the execution time of this air volume calculation, counts as T2. p The timer function, which indicates the execution time of the last air volume calculation, is counted as T2. p-1 Count T2 p-1 Sum of counts T2 p This is stored as a second stamp in the storage device (ROM 61 or RAM 62). In this case, it is counted from T2. p-1 up to count T2 p The time interval (time width) becomes the execution interval for this air volume calculation and processing.

[0047] Furthermore, from count T2 p-1 The counts T3s and T2s of the offset Tx from the past are the offset from the past. p The count T3e, offset by an amount Tx from the past, is stored as a third stamp in the storage device (ROM 61 or RAM 62). In this case, the time interval (time width) from count T3s to count T3e becomes the cumulative interval for the cumulative calculation in this air volume calculation process. That is, from count T2... p-1 up to count T2 p The execution interval (time width) of the current air quality calculation process, offset by only an offset Tx, becomes the cumulative period for the current cumulative calculation. The cumulative calculation of the cumulative air quality calculation unit 77, described later, uses the sensor values ​​detected during this cumulative period.

[0048] Therefore, the offset Tx needs to be set to the value between the count T3e, which is the end time of the current accumulation period, and the count T2, which is the execution time of the current air volume calculation. p During the time interval up to this point (the period of offset Tx), the sensor value of the airflow sensor 51 can be reliably received. This is because if there is no sensor value during this period, it is impossible to infer the flow rate of the intake air at the end of the cumulative period from the sensor value (measured value). Therefore, the offset Tx needs to be set to more than 1 ms, which is the transmission period of SENT communication. However, if the offset Tx is set relatively long, it will correspondingly become a result reflecting past results, and the delay in the calculation result relative to the actual physical phenomenon will increase. Therefore, the offset Tx is preferably set to a value close to 1 ms, which is the transmission period of the sensor value. Figure 5 During the current accumulation period, sensor values ​​are received during counts T1b and T1c. Additionally, sensor values ​​are received during count T1d, which occurs within the time interval from count T3e to count T2p.

[0049] The cumulative air quality calculation unit 77 calculates the cumulative mass of the intake air within the cumulative period set by the cumulative period setting unit 76 based on the sensor value of the airflow sensor 51 and the information from the first stamp. For example, the cumulative air quality calculation unit 77 uses sensor values ​​(intake air flow rate) detected during the cumulative period and sensor values ​​detected before and after the cumulative period to estimate the intake air flow rate at the start and end times of the cumulative period, and uses these estimated values ​​at the start and end times of the cumulative period, along with the sensor values ​​during the cumulative period, to calculate the area within that cumulative period. Specifically, as follows.

[0050] Figure 6 It means Figure 2 The illustration shows an example of a method for calculating the cumulative mass of intake air in the cumulative air mass calculation unit of an internal combustion engine control device according to an embodiment of the present invention. Figure 6 In the diagram, the vertical axis represents the sensor value of the airflow sensor 51 (flow rate of inhaled air in g / s), and the horizontal axis represents the count (time in seconds) of the timer function that shows the elapsed time.

[0051] Linear interpolation is performed on the intake air flow rate during the cumulative period using sensor values ​​detected during the cumulative period and sensor values ​​detected before and after the cumulative period. Figure 6 The area defined by linear interpolation within the cumulative period is the area used to estimate the cumulative mass of air inhaled during the cumulative period. Therefore, calculations are performed separately. Figure 6 The areas S1, S2, and S3 shown are used as the sum of the three areas as the cumulative mass Si of the intake air during the cumulative period.

[0052] exist Figure 6 In this context, T1a to T1d represent the timer counts at which each sensor value is received. Each sensor value is represented as Q1a to Q1d corresponding to its respective timer count. In this formulation, based on the sensor value Q1a detected in timer count T1a before the start time of the accumulation period (past) and the sensor value Q1b detected in timer count T1b after the start time of the accumulation period, the interpolated value Q3s of the start time T3s of the accumulation period is estimated using the following formula (3). Furthermore, based on the sensor value Q1c detected in timer count T1c before the end time of the accumulation period (past) and the sensor value Q1d detected in timer count T1d after the end time of the accumulation period and before the execution time of this air volume calculation process (past), the interpolated value Q3e of the end time T3e of the accumulation period is estimated using the following formula (4). Q 3s =(Q 1b-Q 1a ) / (T 1b -T 1a )×(T 3s -T 1a )+Q 1a …Formula (3) Q 3e =(Q 1d -Q 1c ) / (T 1d -T 1c )×(T 3o -T 1c )+Q 1c …Formula (4)

[0053] Next, calculate the areas S1, S2, and S3. Since each area S1, S2, and S3 is a trapezoid or a rectangle, use the following formulas (5) to (7) to calculate them. S1=(Q 3s +Q 1b )×(T 1b -T 3s Equation (5) / 2 S2=(Q 1b +Q 1c )×(T 1c -T 1b Equation (6) / 2 S3=(Q 1c +Q 3e )×(T 3e -T 1c Equation (7) is ) / 2…

[0054] Next, by calculating the sum of the areas S1, S2, and S3, the cumulative mass Si of the inhaled air during the cumulative period is estimated. That is, Si = S1 + S2 + S3.

[0055] The airflow estimation unit 78 calculates the current calculation time (this time) of the airflow calculation process based on the cumulative mass Si of the intake air during the cumulative period, which is the result of the cumulative air mass calculation unit 77, and the airflow calculation execution interval ΔT, which is the result of the calculation unit 75. I The estimated mass flow rate of the intake air in this air volume calculation process is estimated using the following formula (8). Specifically, the estimated mass flow rate Qm of the intake air is calculated using the following formula (8). The air flow estimation unit 78 then transfers the estimated mass flow rate of the intake air, which is the result of the calculation, to the fuel injection control unit 79. Qm=Si / ΔT I …Formula (8)

[0056] However, if the execution interval ΔT of the air volume calculation is not considered in the calculation of the estimated mass flow rate Qm...I Given the aforementioned changes, and considering that the execution interval of the air volume calculation process is treated as a fixed value along with the 2ms JOB calculation cycle, it is predicted that the mass flow rate Qm will change. In the calculation of the fuel injection control unit 79, since the amount of fuel to be injected is calculated based on the intake air volume and the target air-fuel ratio, if the calculated intake air volume deviates significantly from the actual air volume, the fuel injection amount will also deviate from the appropriate amount, thus raising concerns about deterioration in exhaust performance. In internal combustion engines, air-fuel ratio feedback control is typically used to correct for a lean air-fuel ratio by increasing the fuel injection amount, and conversely, to correct for a rich air-fuel ratio by decreasing the fuel injection amount, thereby controlling the exhaust air-fuel ratio to always be close to the target value. Therefore, even if the calculated intake air volume deviates from the actual air volume, from a long-term perspective, the air-fuel ratio is controlled near the target air-fuel ratio through feedback control. However, from a short-term perspective, the deviation in the air-fuel ratio increases, leading to deterioration in exhaust performance.

[0057] Therefore, in this embodiment, the air volume calculation execution interval calculation unit 75 of the ECU60 calculates the execution interval (time width) ΔT for each air volume calculation process each time the calculation process is performed. I Therefore, the estimated mass flow rate Qm of the intake air calculated using equation (8) takes into account the execution interval ΔT of the air volume calculation process. I The calculation is affected by variations in air volume. Therefore, it is possible to prevent a decrease in the accuracy of the estimated mass flow rate Qm due to variations in the execution interval of the air volume calculation process.

[0058] The fuel injection control unit 79 uses the estimated airflow Qm calculated by the airflow estimation unit 78 to calculate the necessary fuel injection amount. The fuel injection amount calculation process determines the amount of fuel to be injected based on the cumulative mass of air drawn into the combustion chamber 14; therefore, the execution interval of this calculation process is set to be relatively longer than the execution interval of the airflow calculation process described above. For example, for an airflow calculation process allocated to 2 ms JOB, the fuel injection amount calculation process is allocated to 10 ms JOB.

[0059] The fuel injection control unit 79 also sends a control signal to the fuel injection valve 41 corresponding to the calculated fuel injection quantity. Specifically, since the fuel injection quantity of the fuel injection valve 41 is determined by the fuel pressure and the injection period, the injection period is calculated based on the fuel pressure and the calculated fuel injection quantity. A pulse signal with a pulse width (duty cycle) corresponding to the calculated injection period is sent to the fuel injection valve 41 as a fuel injection command signal. As a result, the fuel injection valve 41 is opened during the period corresponding to the duty cycle of the fuel injection command signal, thereby injecting the amount of fuel corresponding to the calculated result into the intake port 20a.

[0060] Next, use Figure 7 An example illustrating the processing steps for calculating the intake air flow rate in an ECU according to one embodiment of the present invention. Figure 7 It means Figure 2 The flowchart shown is an example of a processing step involving air quantity calculation processing in an internal combustion engine control device according to an embodiment of the present invention.

[0061] exist Figure 7 In the middle, ECU60's MPU63 ( Figure 2 The sensor value acquisition unit 71 shown first receives the detection signal transmitted from the airflow sensor 51 via SENT communication, and stores the received detection signal as a sensor value in the storage device (ROM 61 or RAM 62) (step S10). Next, the MPU 63 ( Figure 2 The first timestamp processing unit 72 shown stores the timer count, which represents the moment when the detection signal (sensor value) of the airflow sensor 51 is received, as a first timestamp and associates it with the sensor value received by the storage device (ROM 61 or RAM 62) (step S20).

[0062] Next, MPU63 determines whether the execution flag for air volume calculation processing is true (step S30). If the execution flag is false ("No"), steps S10 and S20 are repeated until the execution flag is true. That is, the following steps are repeated: receiving a detection signal (sensor value) from the airflow sensor 51, storing the received sensor value, and storing the timer count at the time of reception as a first timestamp. On the other hand, if the execution flag is true ("Yes"), step S40 is entered to perform air volume calculation processing.

[0063] In step S40, MPU63 ( Figure 2The second timestamp processing unit 74 shown stores the timer count at the time when the execution flag of the current air volume calculation process is set as the second timestamp of the current calculation time (this time) in the storage device (ROM61 or RAM62). At this time, the second timestamp of the previous air volume calculation process is also stored unchanged in the storage device (ROM61 or RAM62).

[0064] Next, MPU63 ( Figure 2 The cumulative period setting unit 76 shown sets the cumulative period for the cumulative calculation of the intake air (step S50). Specifically, the calculation result obtained by subtracting the offset Tx from the previous second timestamp is stored in the storage device (ROM 61 or RAM 62) as the start time point of the cumulative period, i.e., the third timestamp T3s, and the calculation result obtained by subtracting the offset Tx from the current second timestamp is stored in the storage device (ROM 61 or RAM 62) as the end time point of the cumulative period, i.e., the third timestamp T3e.

[0065] Next, MPU 63 ( Figure 2 The cumulative air quality calculation unit 77 shown calculates the cumulative mass of the inhaled air during the cumulative period set in step S50 (step S60). Specifically, as described above, the flow rate of the inhaled air at each time point is estimated by interpolating the sensor values ​​of the airflow sensor 51 obtained before and after the start and end times of the current cumulative period. The calculation of the cumulative mass of the inhaled air during the cumulative period is equivalent to calculating... Figure 6 The area enclosed by the sensor value and the interpolated estimated value during the cumulative period is shown. That is, the area S1, area S2 and area S3 are calculated using the above equations (5), (6) and (7), respectively, and the cumulative mass Si of the inhaled air during the cumulative period is calculated based on the sum of these areas S1, S2 and S3.

[0066] Next, MPU63 ( Figure 2 The air volume calculation execution interval calculation unit 75) shown calculates the execution interval (time width) of the current air volume calculation process (step S70). As mentioned above, the air volume calculation process is not limited to a constant period (execution interval), so the correct execution interval (time width) is calculated each time the air volume calculation process is executed. Specifically, the previous second timestamp and the current second timestamp stored in the storage device (ROM 61 or RAM 62) in step S20 are retrieved, and the difference between the current second timestamp and the previous second timestamp is calculated and set as the execution interval ΔT of the current air volume calculation process. I .

[0067] Finally, MPU63 ( Figure 2 The airflow estimation unit 78 shown uses the calculation results from step S60 and step S70 to calculate the mass flow rate of the intake air in this airflow calculation process (step S80). Specifically, the cumulative mass of the intake air, which is the calculation result of step S60, is divided by the execution interval ΔT of this airflow calculation process, which is the calculation result of step S70. I The estimated mass flow rate Qm is calculated. The estimated mass flow rate Qm calculated in the air quantity calculation process is the information used for the calculation of the fuel injection quantity in the fuel injection control unit 79 mentioned above.

[0068] Thus, in this embodiment, when calculating the estimated mass flow rate Qm, the execution interval of the current air volume calculation process is calculated using timer counting based on the time point when the execution flag is established. Therefore, compared to the case where the estimated mass flow rate Qm is calculated as a fixed value without considering variations in the execution interval of the air volume calculation process, the accuracy of the estimated mass flow rate Qm can be improved. Consequently, the calculation accuracy of the fuel injection quantity in the fuel injection control unit 79 can be improved accordingly.

[0069] As described above, an ECU 60 (internal combustion engine control device) according to one embodiment of the present invention includes: an MPU 63 (processing device) that repeatedly performs air volume calculation processing at time intervals, the air volume calculation processing estimating the intake air flow rate based on the detection value of an airflow sensor 51 (flow sensor) that detects the intake air flow rate of the engine 1 (internal combustion engine); and a storage device (ROM 61 or RAM 62) that stores information required for the air volume calculation processing of the MPU 63 (processing device). The MPU 63 (processing device) is configured to acquire the detection value of the airflow sensor 51 (flow sensor) at a predetermined acquisition period shorter than the execution interval of the air volume calculation processing, and store it in the storage device (ROM 61 or RAM 62), storing the time when the detection value of the airflow sensor 51 (flow sensor) is acquired as a first timestamp T1 in the storage device (ROM 61 or RAM 62) corresponding to the detection value of the airflow sensor 51 (flow sensor), and storing the time when each execution of the air volume calculation processing is performed as a second timestamp T2 in the storage device (ROM 61 or RAM 62). In each air volume calculation process of the MPU63 (processing device), the execution interval ΔT for calculating the current time point is performed based on the second timestamp T2 stored in the storage device (ROM61 or RAM62). IThe execution interval calculation is performed by setting an accumulation period with the same time width as the execution interval of the current time point based on the second timestamp T2 stored in the storage device (ROM61 or RAM62). Based on the detection value of the airflow sensor 51 (flow sensor) stored in the storage device (ROM61 or RAM62) and its corresponding first timestamp T1, the cumulative mass of the intake air within the set accumulation period is calculated. Based on the calculation result of the accumulation calculation and the calculation result of the execution interval calculation, the estimated flow rate of the intake air within the set accumulation period is estimated.

[0070] According to this structure, the MPU63 (processing device) calculates the execution interval ΔT of each air volume calculation process based on a second timestamp stored in the storage device (ROM61 or RAM62). I The execution interval ΔT using the calculation result I To estimate the intake air flow rate Qm, even if the execution interval ΔT for calculating this air volume is... I The variation is not a constant period, and the execution interval ΔT of the air volume calculation and processing can also be excluded. I The impact of changes on the estimated mass flow rate Qm of the calculation results. That is, even if the execution interval ΔT of the air volume calculation processing of MPU63 (processing unit) is... I Even with changes, the amount of air intake can be estimated with high accuracy.

[0071] Furthermore, in this embodiment, the execution interval calculation of the MPU63 (processing device) is based on the second timestamp T2 corresponding to the execution time point of the current calculation process. p Subtract the previous second timestamp T2 corresponding to the execution time of the operation that occurred one time earlier than the current time. p-1 The calculation is as follows. In addition, the estimated flow rate calculation of MPU63 (processing device) is a calculation that divides the cumulative mass of the intake air, which is the result of the cumulative calculation, by the difference of the second timestamp, which is the result of the execution interval calculation.

[0072] According to this structure, since the execution interval of each air volume calculation is calculated by using the difference of the second timestamp representing the time when each air volume calculation is performed, the execution interval of each air volume calculation can be calculated correctly and easily.

[0073] [Other Implementation Methods] Furthermore, the present invention is not limited to this embodiment and includes various modifications. The above-described embodiments are detailed for ease of understanding and explanation of the present invention, and the present invention is not necessarily limited to including all the structures described. Additionally, a portion of the structure of one embodiment may be replaced with a structure of another embodiment, and a structure of another embodiment may be added to the structure of one embodiment. Furthermore, regarding a portion of the structure of each embodiment, other structures may be added, deleted, or replaced.

[0074] For example, in one embodiment described above, an example is shown where the ECU 60 performs the steps of air volume calculation processing by executing software. However, a structure can also be adopted by installing hardware such as circuitry devices that have the same functionality as the software execution.

[0075] Furthermore, in one of the above embodiments, the air volume calculation execution interval calculation unit 75 is shown calculating the execution interval ΔT from each air volume calculation process. I The second timestamp T2 of this event is stored in the storage device. p Subtract the previous second timestamp T2 p-1 An example of the difference obtained. However, it is also possible to use the difference (T3e-T3s) between the third timestamp T3e at the end of the cumulative period and the third timestamp T3s at the start time to calculate the execution interval ΔT of each air volume calculation process of the air volume calculation execution interval calculation unit 75. I .

[0076] In this modified example, each time the MPU63 (processing device) performs air volume calculation, it stores the start and end times of the set cumulative period as third timestamps T3s and T3e, respectively, in the storage device (ROM61 or RAM62). Furthermore, the execution interval calculation of the MPU63 (processing device) is an operation that subtracts the third timestamp T3s corresponding to the start time from the third timestamp T3e corresponding to the end time of the set cumulative period. Additionally, the estimated flow rate calculation of the MPU63 (processing device) is an operation that divides the cumulative mass Si of the intake air (the result of the cumulative calculation) by the difference between the third timestamps T3s and T3e (the result of the execution interval calculation).

[0077] Based on this structure, the execution interval ΔT for each air volume calculation is calculated using the difference between the third timestamps T3s and T3e corresponding to the start and end times within the cumulative period. I Therefore, the impact of changes in the execution interval of the air volume calculation process on the calculation results of the intake air flow rate during the cumulative period must be excluded. Label Explanation

[0078] 1. Engine (internal combustion engine) 51. Airflow sensor (flow sensor) 60 ECU (Internal Combustion Engine Control Unit) 61 ROM (Storage Device) 62MB RAM (storage device) 63 MPU (Processing Unit) 71 Sensor Value Acquisition Unit 72 First Timestamp Processing Department 74 Second Timestamp Processing Department 75. Execution Interval Calculation Unit (Execution Interval Calculation) 76. Cumulative Period Setting Department 77. Cumulative Air Quality Calculation Department (Cumulative Calculation) 78. Airflow estimation unit (estimated flow calculation).

Claims

1. An internal combustion engine control device, comprising: The processing device repeatedly performs air volume calculation processing at time intervals, the air volume calculation processing being based on the detection value of a flow sensor that detects the flow rate of the intake air of the internal combustion engine to estimate the intake air flow rate; as well as A storage device that stores information required for the air volume calculation and processing by the processing device. The internal combustion engine control device is characterized in that... The processing device is configured such that, The detection value of the flow sensor is acquired at a predetermined acquisition cycle that is shorter than the execution interval of the air volume calculation process, and stored in the storage device. The time when the flow sensor detects the value is acquired is used as the first timestamp and stored in the storage device corresponding to the flow sensor's detection value. The time of each air volume calculation is used as a second timestamp and stored in the storage device. In each of the air volume calculation processes of the processing device, The execution interval calculation is performed based on a second timestamp stored in the storage device, wherein the execution interval calculation calculates the execution interval for the computation processing at the current time point. The accumulation period is set based on a second timestamp stored in the storage device, the accumulation period having the same time width as the execution interval of the computation processing at the current time point. The cumulative calculation is performed based on the detection values ​​of the flow sensor stored in the storage device and their corresponding first timestamps. The cumulative calculation calculates the cumulative mass of inhaled air within a set cumulative period. Based on the calculation results of the cumulative calculation and the calculation results of the execution interval calculation, the estimated flow rate is calculated to estimate the flow rate of the inhaled air within the set cumulative period.

2. The internal combustion engine control device as described in claim 1, characterized in that, The execution interval calculation of the processing device is to calculate the difference of the second timestamp by subtracting the second timestamp corresponding to the execution time of the previous execution of an operation that occurred one time earlier than the current execution time from the second timestamp of the current execution. The estimated flow rate calculation of the processing device is to divide the cumulative mass of the intake air, which is the result of the cumulative calculation, by the difference of the second timestamp.

3. The internal combustion engine control device as described in claim 1, characterized in that, In each air volume calculation process of the processing device, the start time and end time of the set cumulative period are also stored as third timestamps in the storage device. The execution interval calculation of the processing device is to calculate the difference of the third timestamp by subtracting the third timestamp corresponding to the start time from the third timestamp corresponding to the end time point of the set cumulative period. The estimated flow rate calculation of the processing device is to divide the cumulative mass of the intake air, which is the result of the cumulative calculation, by the difference of the third timestamp.

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