JP2018059428A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable zero point adjustment of an air flow meter to be performed when an intake amount of air to an engine reliably becomes 0.SOLUTION: A control device 15 for an internal combustion engine performs drive control of an injector 4 of the internal combustion engine 1, and when an output value of a differential pressure sensor 12 provided at an exhaust side of the internal combustion engine 1 is a prescribed value or less in stopping the internal combustion engine 1, zero point adjustment of an air flow meter 8 for measuring an intake amount to the internal combustion engine 1 is performed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device for an internal combustion engine.

  An engine ECU (Electronic Control Unit) that electronically controls the engine inputs a detection signal from an air flow meter that detects the amount of air sucked into the engine as one of various input information. In the air flow meter, the zero point of the detection signal, that is, the reference voltage may change due to deterioration with time. If the reference voltage of the air flow meter changes, the detection signal of the air intake amount becomes inaccurate, and it is necessary to correct the detection signal. As an example of a configuration for correcting a detection signal, a configuration of Patent Document 1 is known.

  In the configuration of Patent Document 1, the air flow meter is detected when a predetermined operating state is reached, specifically when the engine speed, gear position, throttle opening, and vehicle speed are set values, respectively. The zero point adjustment of the signal is performed, and the correction value of the detection signal is obtained.

Japanese Utility Model Publication No. 61-186754

  In the case of the above-described conventional configuration, the air intake amount to the engine changes even when a predetermined operating state is reached, for example, when the wind is blowing strongly around the vehicle, or in an exhaust duct at a dealer or a vehicle factory, etc. May be attached. In such a case, when the zero point adjustment of the air flow meter is executed, the erroneous zero point adjustment is performed, and the correction value of the detection signal may be inaccurate.

  An object of the present invention is to provide a control device for an internal combustion engine that can perform zero point adjustment of an air flow meter when the amount of air sucked into the engine becomes zero.

  The invention of claim 1 is an internal combustion engine control device 15 for driving and controlling the injector 4 of the internal combustion engine 1, and the differential pressure provided on the exhaust side of the internal combustion engine 1 when the internal combustion engine 1 is stopped. When the output value of the sensor 12 is equal to or less than a predetermined value, the zero point adjustment of the air flow meter 8 for measuring the intake air amount to the internal combustion engine 1 is performed.

The partially broken side view which shows 1st Embodiment and shows the whole schematic structure of an engine and peripheral structure Block diagram showing engine ECU and peripheral circuit Flow chart of zero point adjustment control Characteristic diagram showing the relationship between air intake volume and airflow meter output value Flowchart of zero point adjustment control showing the second embodiment Flowchart of zero-point adjustment control showing the third embodiment Flowchart of zero-point adjustment control showing the fourth embodiment Flowchart of zero-point adjustment control showing the fifth embodiment

(First embodiment)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, for example, an engine 1 that is an internal combustion engine includes a cylinder 2, a piston 3, and an injector (that is, a fuel injection device) 4. An intake pipe 5 and an exhaust pipe 6 are connected to the upper part of the cylinder 2. A fuel supply pipe 7 is connected to the injector 4.

  The intake pipe 5 is provided with an air flow meter (AFM) 8, an intake air temperature sensor 9, and a throttle valve 10. An exhaust gas aftertreatment device 11 and a differential pressure sensor 12 are disposed in the exhaust pipe 6. Fuel is supplied to the fuel supply pipe 7 by a fuel pump 13.

  The air flow meter 8 measures the amount of air passing through the intake pipe 5, that is, the amount of intake air to the engine 1. The intake air temperature sensor 9 measures the temperature of air passing through the intake pipe 5, that is, the intake air temperature to the engine 1. The throttle valve 10 is a valve that adjusts the intake amount of the intake air or intake mixture to the engine 1 and adjusts the output of the engine 1. The throttle valve 10 is provided with a throttle valve sensor 14 (see FIG. 2) that detects the opening of the throttle valve 10.

  The post-treatment device 11 is a device that purifies exhaust gas discharged from the engine 1, for example. The differential pressure sensor 12 includes a pressure sensor 12a disposed at an intermediate portion of the post-treatment device 11, and a pressure sensor 12b disposed at an outlet portion of the post-treatment device 11, and two pressure sensors 12a and 12b. The difference (that is, voltage value) of the detected pressure value (that is, detected voltage value) is output. When the output voltage value of the differential pressure sensor 12 (ie, the output value) is less than or equal to a predetermined value, it is determined that no exhaust gas is flowing in the exhaust pipe 6, and the output voltage value of the differential pressure sensor 12 exceeds the predetermined value Then, it is determined that the exhaust gas is flowing in the exhaust pipe 6.

  Next, the electrical configuration of the engine ECU 15 that controls the engine 1 and its peripheral circuits will be described with reference to FIG. As shown in FIG. 2, the engine ECU 15 includes an air flow meter 8, a crank angle sensor 16, a transmission switch 17, a vehicle speed sensor 18, a water temperature sensor 19, an intake air temperature sensor 9, a differential pressure sensor 12, and a throttle valve sensor 14. A detection signal is input. The crank angle sensor 16 detects the rotation angle of the crankshaft of the engine 1 and outputs a crank signal. The transmission switch 17 detects a shift position of the transmission of the vehicle and outputs a detection signal. The vehicle speed sensor 18 detects the speed of the vehicle and outputs a detection signal. The water temperature sensor 19 detects the temperature of the cooling water of the engine 1 and outputs a detection signal. Further, the engine ECU 15 controls the drive of the injector 4, the igniter 20, and the throttle valve 10. The engine ECU 15 has a function as a control device for an internal combustion engine.

  The engine ECU 15 includes a microcomputer (not shown) including a CPU 21, a ROM 22, a RAM 23, and a nonvolatile memory 24. The CPU 21 has a function of controlling the entire engine ECU 15 by executing a control program stored in the ROM 22. Various data are temporarily stored in the RAM 23. The non-volatile memory 24 is composed of a flash memory, an EEPROM, or the like, and can write and erase various data. In the nonvolatile memory 24, various data such as a reference value and detection value data table of the air flow meter 8 and a correction value for adjusting the zero point of the air flow meter 8 are stored.

  Next, the operation of the above configuration, that is, the zero point adjustment control of the air flow meter 8 will be described with reference to FIGS. The flowchart of FIG. 3 shows the contents of the zero point adjustment control of the air flow meter 8 in the control of the engine ECU 15. Note that this zero-point adjustment control is configured to be repeatedly executed every set time.

  First, in step S10 of FIG. 3, the engine ECU 15 determines whether or not the internal combustion engine, that is, the engine 1 is stopped. In this case, the engine ECU 15 determines that the engine 1 is stopped, for example, when no crank signal is input from the crank angle sensor 16, that is, when the engine 1 is not rotating. If it is determined in step S10 that the engine 1 is not stopped, the process proceeds to "NO" and this control is terminated.

  When it is determined in step S10 that the engine 1 is stopped (YES), the process proceeds to step S20, and the engine ECU 15 determines that the output voltage value (that is, the output value) of the differential pressure sensor 12 is equal to or less than a predetermined value. It is determined whether or not. Here, when it is determined that the output voltage value of the differential pressure sensor 12 is not less than or equal to the predetermined value, that is, when the exhaust gas is flowing in the exhaust pipe 6, the process proceeds to "NO" and this control is terminated. When it is determined in step S20 that the output voltage value of the differential pressure sensor 12 is equal to or less than a predetermined value, that is, when the exhaust gas is not flowing through the exhaust pipe 6 (YES), the air flow meter 8 is turned on. Proceed to step S30 to perform point adjustment.

  In step S30, the engine ECU 15 acquires the voltage value of the output signal of the air flow meter 8. In this case, since the engine 1 is stopped and no exhaust gas is flowing in the exhaust pipe 6, no air is flowing in the intake pipe 5, so that the acquired output voltage value (that is, output value) is This corresponds to the zero point of the air flow meter 8 (that is, a reference voltage or a reference value).

  Subsequently, the process proceeds to step S40, in which the engine ECU 15 determines the output voltage value acquired from the air flow meter 8 and the reference voltage at the initial time of the air flow meter 8 stored in advance in the nonvolatile memory 24 (that is, the initial value 0). The correction value is calculated based on the point or the reference value, and the calculated correction value is stored in the nonvolatile memory 24. In this case, the detection characteristic of the air flow meter 8 at the initial time, for example, at the time of shipment is indicated by a curve P1 in FIG. In FIG. 4, the horizontal axis represents the air flow rate, and the vertical axis represents the voltage value (ie, output value) of the output signal of the air flow meter 8. From the curve P1, the initial reference voltage of the air flow meter 8 is, for example, about 1V.

  A curve P2 in FIG. 4 shows the detection characteristic when the zero point of the detection signal of the air flow meter 8, that is, the reference voltage changes due to deterioration over time or the like. It can be seen from the curves P1 and P2 that the voltage value (ie, output voltage) of the output signal of the air flow meter 8 is shifted by the amount of change in the reference voltage. For this reason, a value obtained by subtracting the initial reference voltage of the airflow meter 8 stored in advance in the nonvolatile memory 24 from the output voltage value acquired in step S30 is set as a correction value. After that, the voltage value of the output signal of the air flow meter 8 for which the intake air amount is measured, that is, the value obtained by subtracting the correction value from the detected value corresponds to the accurate detected value. Thereby, the zero point adjustment control of the air flow meter 8 is completed.

  In this embodiment having such a configuration, when the engine 1 is stopped by the engine ECU 15, the zero point adjustment of the air flow meter 8 is performed when the output value of the differential pressure sensor 12 is equal to or less than a predetermined value. Thus, when the amount of air sucked into the engine 1 is reliably zero, the zero point adjustment of the air flow meter 8 can be executed, and the zero point adjustment can be performed accurately. That is, according to the above configuration, when the wind is blowing strongly, even if the engine 1 is stopped, the output value of the differential pressure sensor 12 does not become a predetermined value or less. Since this is not executed, it is possible to prevent the correction value for the zero point adjustment from becoming inaccurate.

(Second Embodiment)
FIG. 5 shows a second embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment. In the second embodiment, the zero point adjustment control of the air flow meter 8 is executed only once when the ignition switch of the vehicle is turned on.

  Specifically, in step S110 of FIG. 5, the engine ECU 15 determines whether or not the ignition switch has been turned on from off. Here, when the ignition switch is not turned on from off (that is, when it remains off or remains on), the process proceeds to “NO” and this control is finished. In step S110, when the ignition switch is turned from OFF to ON (YES), the process proceeds to step S10, and the engine ECU 15 determines whether or not the engine 1 is stopped. Each processing after step S10 is executed in the same manner as in the first embodiment.

  The configuration of the second embodiment other than that described above is the same as that of the first embodiment. Therefore, in the second embodiment, substantially the same operational effects as in the first embodiment can be obtained. In particular, according to the second embodiment, the zero point adjustment control of the air flow meter 8 is configured to be executed only once when the ignition switch of the vehicle is turned on from the off state. It is possible to prevent the control from being repeatedly executed in vain.

(Third embodiment)
FIG. 6 shows a third embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 2nd Embodiment. In the third embodiment, as a condition for executing the zero-point adjustment control of the air flow meter 8, a condition that the opening of the throttle valve 10 is equal to or less than a predetermined value is added.

  Specifically, each process of step S110, step S10, and step S20 of FIG. 6 is performed similarly to 2nd Embodiment. Then, the process proceeds to step 210, and the engine ECU 15 determines whether or not the opening degree of the throttle valve 10 is equal to or less than a set value. Here, when the opening degree of the throttle valve is not less than or equal to the set value, the process proceeds to “NO” and this control is terminated.

  When the throttle valve opening is equal to or smaller than the set value in step S210 (YES), the process proceeds to step S30, and the engine ECU 15 acquires the voltage value of the output signal of the air flow meter 8. Each processing after step S30 is executed in the same manner as in the second embodiment.

  The configuration of the third embodiment other than that described above is the same as that of the second embodiment. Therefore, in the third embodiment, substantially the same operational effects as in the second embodiment can be obtained. In particular, according to the third embodiment, as a condition for executing the zero-point adjustment control of the air flow meter 8, the condition that the opening degree of the throttle valve 10 is equal to or less than the set value is added, so the engine 1 is stopped. In addition, when the exhaust gas does not flow in the exhaust pipe 6 and the opening degree of the throttle valve 10 is equal to or less than the set value, that is, the air in the intake pipe 5 is more reliably secured. The zero point adjustment of the air flow meter 8 can be executed when the air flow is not flowing.

(Fourth embodiment)
FIG. 7 shows a fourth embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment. In the fourth embodiment, as a condition for executing the zero point adjustment control of the air flow meter 8, a condition that the temperature of the intake air is lower than the set temperature is added. Note that when the temperature of the intake air is lower than the set temperature, the temperature characteristic of the air flow meter 8 is in a preferable state. That is, when the temperature of the intake air becomes equal to or higher than the set temperature, the temperature characteristics of the air flow meter 8 are deteriorated.

  First, in step S310 of FIG. 6, the engine ECU 15 determines whether or not the temperature of the intake air is lower than the set temperature. Here, when the temperature of the intake air is not lower than the set temperature, the process proceeds to “NO” and this control is terminated.

  In step S310, when the temperature of the intake air is lower than the set temperature (YES), the process proceeds to step S10, and the engine ECU 15 determines whether or not the engine 1 is stopped. Each processing after step S10 is executed in the same manner as in the first embodiment.

  The configuration of the fourth embodiment other than that described above is the same as that of the first embodiment. Therefore, also in the fourth embodiment, substantially the same operational effects as in the first embodiment can be obtained. In particular, according to the fourth embodiment, since the condition that the temperature of the intake air is lower than the set temperature is added as a condition for executing the zero point adjustment control of the air flow meter 8, the engine 1 is stopped, and When the exhaust gas does not flow through the exhaust pipe 6 and the intake air temperature is lower than the set temperature, that is, when the air does not flow reliably through the intake pipe 5. Thus, when the temperature characteristic of the air flow meter 8 is in a preferable state, the zero point adjustment of the air flow meter 8 can be executed.

(Fifth embodiment)
FIG. 8 shows a fifth embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 4th Embodiment. The fifth embodiment is configured such that, in the fourth embodiment, the zero point adjustment control of the air flow meter 8 is executed only once when the ignition switch of the vehicle is turned on.

  Specifically, in step S110 of FIG. 8, the engine ECU 15 determines whether or not the ignition switch has been turned on from off. Here, when the ignition switch is not turned on from off (that is, when it remains off or remains on), the process proceeds to “NO” and this control is finished. In step S110, when the ignition switch is turned on from OFF (YES), the process proceeds to step S310, and the engine ECU 15 determines whether or not the temperature of the intake air is lower than the set temperature. Here, when the temperature of the intake air is not lower than the set temperature, the process proceeds to “NO” and this control is terminated.

  In step S310, when the temperature of the intake air is lower than the predetermined temperature (YES), the process proceeds to step S10, and the engine ECU 15 determines whether or not the engine 1 is stopped. Each process after step S10 is executed in the same manner as in the fourth embodiment.

  The configuration of the fifth embodiment other than that described above is the same as that of the fourth embodiment. Accordingly, in the fifth embodiment, substantially the same operational effects as in the fourth embodiment can be obtained. In particular, in the fifth embodiment, as a condition for executing the zero-point adjustment control of the air flow meter 8, the condition that it is executed only once when the ignition switch of the vehicle is turned on is added. This zero-point adjustment control can be prevented from being repeatedly performed in vain.

  Further, in the fifth embodiment shown in FIG. 8, step S210 of the third embodiment shown in FIG. 6 may be added between step S20 and step S30. In the fourth embodiment shown in FIG. 7, step S210 of the third embodiment shown in FIG. 6 may be added between step S20 and step S30.

  In each of the above embodiments, when the zero point adjustment of the air flow meter 8 is performed, the difference between the output value of the air flow meter 8 and the reference value of the air flow meter 8 is used as a correction value. It is not limited. For example, when zero adjustment of the air flow meter 8 is performed by the engine ECU 15, an average value between the output value of the air flow meter 8 and the reference value of the air flow meter 8 is calculated, and this average value and the reference value of the air flow meter 8 are calculated. It may be configured to use the difference between the two as a correction value. If comprised in this way, when the zero point adjustment of the air flow meter 8 is carried out, it can prevent as much as possible that the detection characteristic of the air flow meter 8 changes a lot.

  Further, in each of the above embodiments, when the zero point adjustment of the air flow meter 8 is performed, the difference between the output value of the air flow meter 8 and the reference value of the air flow meter 8 is used as a correction value. For example, when the zero point adjustment of the air flow meter 8 is performed, the output value of the air flow meter 8 is set as a new reference value of the air flow meter 8 and stored in the nonvolatile memory 24. You may do it. In the case of such a configuration, a detection value data table of the air flow meter 8 (that is, a data table in which the output value of the air flow meter 8 and the detection value of the intake air amount are in one-to-one correspondence) is also created to create a nonvolatile memory. 24 is preferably configured to be stored in 24.

  Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

In the drawings, 1 is an engine, 4 is an injector, 5 is an intake pipe, 6 is an exhaust pipe, 8 is an air flow meter, 9 is an intake air temperature sensor, 10 is a throttle valve, 12 is a differential pressure sensor, 14 is a throttle valve sensor, 15 Is an engine ECU, 16 is a crank angle sensor, 18 is a vehicle speed sensor, and 24 is a nonvolatile memory.

Claims (6)

An internal combustion engine control device (15) for driving and controlling an injector (4) of the internal combustion engine (1),
When the internal combustion engine is stopped, an air flow meter that measures the intake air amount to the internal combustion engine when the output value of the differential pressure sensor (12) provided on the exhaust side of the internal combustion engine is equal to or less than a predetermined value. A control device for an internal combustion engine configured to perform the zero point adjustment of 8).   The control device for an internal combustion engine according to claim 1, wherein the control unit is configured to perform zero-point adjustment of the air flow meter when the ignition switch is turned on from off.   The control device for an internal combustion engine according to claim 1 or 2, wherein the zero point adjustment of the air flow meter is performed when the opening of the throttle valve (10) is equal to or less than a set value.   The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the control unit is configured to perform zero-point adjustment of the air flow meter when the intake air temperature is lower than a set temperature.   5. The apparatus according to claim 1, wherein when the zero point adjustment of the air flow meter is performed, a difference between an output value of the air flow meter and a reference value of the air flow meter is used as a correction value. 6. Control device for internal combustion engine. When the zero point adjustment of the air flow meter is performed, an average value between the output value of the air flow meter and the reference value of the air flow meter is calculated, and a difference between the average value and the reference value of the air flow meter is used as a correction value. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the control device is configured to be used.

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