WO2013103018A1 - 内燃機関の吸入空気量計測装置 - Google Patents
内燃機関の吸入空気量計測装置 Download PDFInfo
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- WO2013103018A1 WO2013103018A1 PCT/JP2012/050200 JP2012050200W WO2013103018A1 WO 2013103018 A1 WO2013103018 A1 WO 2013103018A1 JP 2012050200 W JP2012050200 W JP 2012050200W WO 2013103018 A1 WO2013103018 A1 WO 2013103018A1
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- crank angle
- interval
- internal combustion
- combustion engine
- intake air
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
- F02M35/10—Air intakes; Induction systems
- F02M35/10373—Sensors for intake systems
- F02M35/10386—Sensors for intake systems for flow rate
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/009—Electrical control of supply of combustible mixture or its constituents using means for generating position or synchronisation signals
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/72—Devices for measuring pulsing fluid flows
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/06—Indicating or recording devices
- G01F15/068—Indicating or recording devices with electrical means
Definitions
- the present invention relates to an intake air amount measuring device for an internal combustion engine, and more particularly to an intake air amount measuring device for an internal combustion engine that measures an intake air amount based on an output signal of an air flow meter disposed in an intake passage of the internal combustion engine.
- an internal combustion engine such as a gasoline engine or a diesel engine mounted on a vehicle or the like
- the amount of air sucked into a combustion chamber (cylinder) is measured, and various control amounts are determined based on the amount of intake air that is the measured value.
- the fuel injection amount for example, fuel injection amount, etc.
- the output is improved and the exhaust emission is reduced (for example, NOx is reduced).
- an air flow meter disposed in the intake passage is used for measuring the intake air amount (see, for example, Patent Document 1).
- the output signal of the air flow meter is taken into an ECU (electronic control unit) at a predetermined time interval (for example, 4 msec) (taken in time synchronization), and every predetermined period, An average value (average flow rate of intake air) of sampling values (hereinafter also referred to as AFM data) of an output signal (hereinafter also referred to as AFM signal) of the air flow meter is sequentially calculated. Then, control of the internal combustion engine (fuel injection amount control or the like) is performed using the average flow rate of the intake air thus calculated.
- AFM data average flow rate of sampling values
- AFM signal an output signal
- the output value of the air flow meter also changes instantaneously due to the intake pulsation. Therefore, in the process of acquiring the AFM signal in time synchronization, the AFM signal is converted into the ECU. If the timing of taking in is improper, the average value (average flow rate calculation value) of the AFM data may fluctuate greatly or aliasing may occur.
- the present invention has been made in view of such circumstances, and provides an intake air amount measuring device for an internal combustion engine that can accurately obtain the average flow rate of intake air by eliminating the influence of intake pulsation. With the goal.
- the present invention relates to an intake air amount measuring device for an internal combustion engine that includes an air flow meter disposed in an intake passage of the internal combustion engine and measures an intake air amount into a combustion chamber of the internal combustion engine based on an output signal of the air flow meter.
- the present invention is characterized in that the output signal of the air flow meter is sampled in synchronization with the crank angle of the internal combustion engine.
- the output signal of the air flow meter is sampled at a predetermined crank angle interval in synchronization with the crank angle of the internal combustion engine.
- the crank angle interval is set in accordance with the period of the intake pulsation.
- the crank angle interval is a value obtained by dividing the crank angle 360 ° by an integer of 2 or more, and a value obtained by dividing the crank angle corresponding to one cycle of the internal combustion engine by the number of cylinders of the internal combustion engine. Exclude crank angle interval.
- the present invention is characterized in that an average value of a plurality of AFM data obtained by sampling an output signal of an air flow meter in synchronization with a crank angle of an internal combustion engine is calculated to obtain an average flow rate of intake air.
- the output signal (AFM signal) of the air flow meter is sampled in synchronization with the crank angle of the internal combustion engine, the AFM signal (AFM data) is acquired at regular intervals within one cycle of the intake pulsation. It is possible to eliminate the influence of the intake pulsation. Thereby, fluctuations in the average value of the AFM data can be suppressed, and the average flow rate of the intake air can be calculated with high accuracy.
- crank angle interval for sampling the output signal of the air flow meter is switched (changed) in accordance with the engine speed (engine speed) of the internal combustion engine. More specifically, when the engine speed of the internal combustion engine is high, the crank angle interval can be set larger than when the engine speed is low. By adopting such a configuration, it is possible to avoid an increase in the processing load of the ECU even when the engine speed of the internal combustion engine increases.
- the AFM when the crank angle interval is switched, if the crank angle interval before and after the switching has a multiple relationship, the AFM is used by using the sampling value acquired at the larger crank angle interval among the crank angle intervals before and after the switching. Calculate the average value of the data.
- AFM data can be sampled at equal intervals (or sampled at the crank angle interval after switching) even within one cycle of the intake pulsation when the crank angle interval is switched.
- fluctuations in the average value (average flow rate of intake air) of AFM data can be suppressed.
- crank angle interval when the crank angle interval is switched, when the crank angle interval before and after the switching has a non-multiple relationship, a value obtained by linearly interpolating two sampling values acquired at the crank angle interval before the switching, and after the switching The average value is calculated using the sampling values obtained at the crank angle intervals.
- the output signal of the air flow meter is sampled in synchronization with the crank angle of the internal combustion engine, so that the influence of intake pulsation can be eliminated. Thereby, the average flow rate of the intake air can be calculated with high accuracy.
- FIG. 1 shows only the configuration of one cylinder of the engine.
- An engine 1 shown in FIG. 1 is an in-cylinder direct injection four-cylinder diesel engine mounted on a vehicle, and a piston 1c that reciprocates in the vertical direction is provided in a cylinder block 1a constituting each cylinder. .
- the piston 1c is connected to the crankshaft 15 via the connecting rod 16, and the reciprocating motion of the piston 1c is converted into rotation of the crankshaft 15 by the connecting rod 16.
- the crankshaft 15 of the engine 1 is connected to a transmission (not shown), and can transmit power from the engine 1 to drive wheels (not shown) of the vehicle via the transmission.
- a signal rotor 17 is attached to the crankshaft 15.
- a crank position sensor (engine speed sensor) 25 for detecting a crank angle is disposed near the side of the signal rotor 17.
- the crank position sensor 25 is, for example, an electromagnetic pickup, and generates a pulsed signal (voltage pulse) corresponding to the teeth 17a of the signal rotor 17 when the crankshaft 15 rotates.
- the engine speed can be calculated from the output signal of the crank position sensor 25.
- a water temperature sensor 21 for detecting the engine cooling water temperature is disposed in the cylinder block 1a of the engine 1.
- a cylinder head 1b is provided at the upper end of the cylinder block 1a, and a combustion chamber 1d is formed between the cylinder head 1b and the piston 1c.
- An oil pan 18 for storing engine oil is provided below the cylinder block 1a of the engine 1.
- the engine oil stored in the oil pan 18 is pumped up by an oil pump through an oil strainer that removes foreign matters during operation of the engine 1 and further purified by an oil filter, and then the piston 1c, the crankshaft 15, and the connecting oil. It is supplied to the rod 16 and used for lubrication and cooling of each part.
- the cylinder head 1b of the engine 1 is provided with an injector 2 for directly injecting fuel into the combustion chamber 1d of the engine 1.
- a common rail (accumulation chamber) 3 is connected to the injector 2, and fuel in the common rail 3 is injected from the injector 2 into the combustion chamber 1 d while the injector 2 is open.
- a rail pressure sensor 24 for detecting the pressure (rail pressure) of the high pressure fuel in the common rail 3 is disposed on the common rail 3.
- a supply pump 4 that is a fuel pump is connected to the common rail 3.
- the supply pump 4 is driven by the rotational force of the crankshaft 15 of the engine 1.
- fuel is supplied from the fuel tank 40 to the common rail 3, and the injector 2 is opened at a predetermined timing, whereby the fuel is injected into the combustion chamber 1 d of each cylinder of the engine 1.
- the injected fuel is combusted in the combustion chamber 1d and exhausted as exhaust gas.
- the valve opening timing (injection period) of the injector 2 is controlled by an ECU (Electronic Control Unit) 200 described later.
- An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 d of the engine 1.
- An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1d. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1d are communicated or blocked.
- an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1d. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1d are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft and the exhaust camshaft to which the rotation of the crankshaft 15 is transmitted.
- an air cleaner 9, an air flow meter 22 that detects an intake air amount (new air amount), a compressor impeller 102 of a turbocharger 100 described later, and intake air that has been heated by supercharging in the turbocharger 100 are forcibly cooled.
- An intercooler 7, an intake air temperature sensor 23, a throttle valve 6, and an intake manifold pressure sensor (supercharge pressure sensor) 28 for detecting the pressure (supercharge pressure) in the intake manifold 11a are disposed.
- the air flow meter 22 has a high accuracy in the intake air amount even in a high pulsation region where the above-described reverse flow (a reverse flow caused by the return of combustion gas from the combustion chamber to the intake passage) occurs.
- the air flow meter with high responsiveness that can be detected by using is used.
- the throttle valve 6 is disposed in the intake passage 11 on the downstream side (downstream side of the intake air flow) of the intercooler 7 (compressor impeller 102 of the turbocharger 100).
- the throttle valve 6 is an electronically controlled valve whose opening is adjusted by a throttle motor 60.
- the opening of the throttle valve 6 (throttle opening) is detected by a throttle opening sensor 26.
- the throttle valve 6 of this example can electronically control the throttle opening independently of the driver's accelerator pedal operation.
- a NOx occlusion catalyst NSR catalyst: NOx Storage Reduction catalyst
- a maniverter exhaust gas purification device 80 including a DPNR catalyst (Diesel Particle-NOx Reduction catalyst) 82 are disposed.
- an A / F sensor air-fuel ratio sensor 29 is disposed in the exhaust passage 12 on the downstream side of the manipulator 80.
- the engine 1 is equipped with a turbocharger (supercharger) 100 that supercharges intake air using exhaust pressure.
- a turbocharger supercharger 100 that supercharges intake air using exhaust pressure.
- the turbocharger 100 integrally connects the turbine wheel 101 disposed in the exhaust passage 12, the compressor impeller 102 disposed in the intake passage 11, and the turbine wheel 101 and the compressor impeller 102.
- the turbine wheel 101 arranged in the exhaust passage 12 is rotated by the energy of the exhaust, and the compressor impeller 102 arranged in the intake passage 11 is rotated accordingly.
- the intake air is supercharged by the rotation of the compressor impeller 102, and the supercharged air is forcibly sent into the combustion chamber of each cylinder of the engine 1.
- the turbocharger 100 of this example is a variable nozzle type turbocharger (VNT), and a variable nozzle vane mechanism 120 is provided on the turbine wheel 101 side, and the opening degree of the variable nozzle vane mechanism 120 (hereinafter referred to as VN opening degree).
- VNT opening degree the opening degree of the variable nozzle vane mechanism 120
- the supercharging pressure of the engine 1 can be adjusted.
- the engine 1 is equipped with an EGR device 5.
- the EGR device 5 is a device that reduces the combustion temperature in the combustion chamber 1d and reduces the amount of NOx generated by introducing a part of the exhaust gas into the intake air.
- the EGR device 5 includes an exhaust passage 12 upstream of the turbine wheel 101 of the turbocharger 100 (upstream of the exhaust gas flow) and a downstream of the intercooler 7 (compressor impeller 102 of the turbocharger 100).
- An EGR passage 51 communicating with the intake passage 11 on the side (downstream of the intake air flow), an EGR catalyst (for example, an oxidation catalyst) 52 provided in the EGR passage 51, an EGR cooler 53, an EGR valve 54, and the like It is configured.
- the EGR rate [EGR amount / (EGR amount + intake air amount (new air amount)) (%)] is changed by adjusting the opening degree of the EGR valve 54.
- the EGR amount (exhaust gas recirculation amount) introduced from the exhaust passage 12 to the intake passage 11 can be adjusted.
- the EGR device 5 may be provided with an EGR bypass passage that bypasses the EGR cooler 53 and an EGR bypass switching valve.
- the ECU 200 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a backup RAM 204, and the like.
- a CPU Central Processing Unit
- ROM Read Only Memory
- RAM Random Access Memory
- the ROM 202 stores various control programs, maps that are referred to when the various control programs are executed, and the like.
- the CPU 201 executes various arithmetic processes based on various control programs and maps stored in the ROM 202.
- the RAM 203 is a memory that temporarily stores calculation results of the CPU 201, data input from each sensor, and the backup RAM 204 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory.
- the CPU 201, the ROM 202, the RAM 203, and the backup RAM 204 are connected to each other via the bus 207 and to the input interface 205 and the output interface 206.
- the input interface 205 includes a buffer for temporarily storing data and the like, a waveform shaping circuit, an A / D converter, and the like.
- a buffer eg, 30CA buffer, 60CA buffer, 90CA buffer, 120CA
- AFM data acquired at a sampling interval for example, 30CA interval, 60CA interval, 90CA interval, 120CA interval
- the input interface 205 includes a water temperature sensor 21, an air flow meter 22, an intake air temperature sensor 23, a rail pressure sensor 24, a crank position sensor 25, a throttle opening sensor 26 that detects the opening of the throttle valve 6, and an accelerator pedal depression amount.
- An accelerator opening sensor 27 for detecting (accelerator opening), an intake manifold pressure sensor (supercharging pressure sensor) 28, an A / F sensor 29, and the like are connected.
- the output interface 206 is connected to the injector 2, the throttle motor 60 of the throttle valve 6, the EGR valve 54, and the like.
- the ECU 200 controls the engine 1 including the opening control of the throttle valve 6 of the engine 1, fuel injection amount / injection timing control (injector 2 opening / closing control), EGR control, and the like based on the output signals of the various sensors described above. Perform various controls.
- the ECU 200 executes the following “AFM data acquisition process” and “average flow rate calculation process”. Note that the average flow rate calculation values calculated by these “AFM data acquisition processing” and “average flow rate calculation processing” are used for control of the engine 1 (fuel injection amount control, EGR control, etc.).
- the intake air amount measuring device of the present invention is realized by the air flow meter 22 and the ECU 200 described above.
- the output value of the air flow meter 22 also changes instantaneously due to the intake pulsation.
- the average value (average flow rate calculation value) of the AFM data may vary greatly. For example, when the sampling period (for example, 4 msec) coincides with the peak of the pulsation period of the intake pulsation, the average value of the AFM data becomes large, and when the sampling period coincides with the bottom of the pulsation period of the intake pulsation. The average value of AFM data becomes small.
- the average value (average flow rate calculation value) of AFM data may fluctuate greatly depending on the timing at which the AFM signal is taken into ECU 200.
- an error (aliasing) of the average value of AFM data may occur.
- the timing at which the AFM signal is captured in time synchronization is increased, the variation in the average value of the AFM data can be reduced.
- the processing load on the ECU increases, there is a limit to increasing the acquisition timing. Note that when the AFM signal is output in pulses (frequency), there is a limit to speeding up the acquisition timing.
- processing is performed at the same angular cycle as the pulsation cycle of the intake pulsation.
- processing is performed in which the output signal (AFM signal) of the air flow meter 22 is sampled at equal intervals to calculate the average flow rate of the intake air.
- AFM data acquisition processing First, an example of AFM data acquisition processing will be described with reference to the flowchart of FIG. 3
- the processing routine of FIG. 3 is repeatedly executed in the ECU 200 every predetermined time (for example, every 4 msec).
- step ST101 the engine speed is calculated from the output signal of the crank position sensor 25.
- step ST102 based on the engine speed calculated in step ST101, the crank angle interval (crank angle interval for sampling the output signal of the air flow meter 22: for example, 30CA, 60CA, 90CA, 120CA).
- crank angle interval for sampling the output signal of the air flow meter 22: for example, 30CA, 60CA, 90CA, 120CA.
- step ST103 based on the output signal of the crank position sensor 25, the output signal (AFM signal) of the air flow meter 22 at every crank angle interval (30CA, 60CA, 90CA or 120CA) set in step ST102. And the sampled AFM data is stored (temporarily stored) in a buffer in ECU 200.
- crank angle interval setting process Next, processing for setting the crank angle interval for sampling the output signal of the air flow meter 22 will be described.
- crank angle interval used in this example is a value obtained by dividing an angle 360 ° (crank angle) at which the crankshaft 15 of the engine 1 rotates once by an integer of 2 or more (this condition is referred to as [condition J1]). ).
- crank angle interval when an integer of 2 or more is “12”, the crank angle interval is 30 ° (hereinafter also referred to as 30CA interval), and when the integer of 2 or more is “6”, the crank angle interval is 60 °. (Hereinafter also referred to as 60 CA interval).
- the crank angle interval is 90 ° (hereinafter also referred to as 90CA interval), and when the integer greater than 2 is “3”, the crank angle interval is 120 °. (Hereinafter also referred to as 120 CA interval).
- the intake pulsation described above occurs corresponding to the intake stroke of each cylinder of the engine 1. For example, if the engine has four cylinders, intake pulsation occurs four times (four cycles) during one cycle (720 °), so the cycle of intake pulsation in each cylinder is 180 ° crank angle (180 CA). . For this reason, in the 4-cylinder engine 1, when the crank angle interval for sampling the output signal of the air flow meter 22 is 180 CA, the sampling cycle and the intake pulsation cycle are the same. In some cases, only the peak value (AFM data) is sampled. Conversely, only the bottom of the pulsation cycle (AFM data) may be sampled. In such a situation, the average value of the AFM data cannot be accurately calculated. In order to avoid this, in this example, an angle (720 ° / number of cylinders) obtained by dividing one cycle (720CA) by the number of cylinders is excluded.
- the crank angle interval for obtaining the AFM signal is switched according to the engine speed of the engine 1. Specifically, when the engine speed is high, the crank angle interval for acquiring the AFM signal is set to a larger value than when the engine speed is low.
- the map (table) shown in FIG. 4 is set in advance based on the above conditions ([Condition J1], [Condition J2], etc.).
- a crank angle interval (hereinafter also referred to as a sampling interval) for obtaining the output signal (AFM signal) of the air flow meter 22 is set.
- the sampling interval is set to 30 CA.
- the sampling interval is 60 CA, and when the engine speed is [3800 rpm or more (3800 rpm)], the sampling interval is 120 CA.
- the map shown in FIG. 4 is stored in the ROM 202 of the ECU 200.
- an overlap rotation region (1800 rpm to 2000 rpm) in which the engine rotation speed at 30 CA intervals and the engine rotation speed at 60 CA intervals overlap is provided.
- the reason for this is that the switching interval (engine speed) switches the sampling interval from 30 CA to 60 CA when the engine speed is increasing, and the sampling interval is 60 CA to 30 CA when the engine speed is decreasing. This is to provide hysteresis to the switching value (engine speed) switched to the interval.
- the sampling interval is switched from the 30 A interval to the 60 CA interval when the increasing engine speed reaches 2000 rpm.
- the sampling interval is switched from 60 A interval to 30 CA when the decreasing engine rotation speed becomes 1800 rpm or less.
- the sampling interval is switched from the 60 A interval to the 120 CA interval when the increasing engine speed reaches 4000 rpm.
- the sampling interval is switched from the 120A interval to 60CA when the decreasing engine rotation speed becomes 3800 rpm or less.
- the sampling interval of the AFM signal is set to 4 msec (time synchronization) for the low speed range where the engine speed is less than 500 rpm.
- the reason for this is that if the sampling interval (30 CA) is set in a low rotation range of less than 500 rpm, the sampling time of the AFM signal becomes long, and the accuracy of calculating the average value of the AFM data is lowered.
- the AFM signal is sampled in time synchronization (4 msec).
- AFM data is always acquired at crank angle intervals when the engine 1 is in operation (including idling operation state). There is no problem because it can.
- crank angle interval set in step ST102 of the processing routine of FIG. 3 is, for example, 30 CA intervals
- AFM data is acquired every 30 CA intervals and a 30 CA buffer in the ECU 200 (see FIG. 8).
- the crank angle interval for acquiring AFM data is switched from 30 CA to 60 CA intervals (see FIG. 8), and AFM data is acquired every 60 CA intervals to obtain the ECU 200.
- the crank angle interval for acquiring AFM data is switched from 60 CA interval to 120 CA interval, and AFM data is acquired every 120 CA interval and stored in a 120 CA buffer in ECU 200.
- the crank angle interval is switched from 120 CA intervals to 60 CA intervals, and AFM data is acquired at 60 CA intervals.
- the data is stored in a 60CA buffer in the ECU 200.
- the crank angle interval is switched from 60 CA interval to 30 CA interval, AFM data is acquired at 30 CA interval, and stored in the 30 CA buffer in ECU 200.
- crank angle intervals for sampling the output signal (AFM signal) of the air flow meter 22 are 30 CA intervals, 60 CA intervals, and 120 CA intervals.
- the AFM signal is The sampling crank angle intervals may be 30 CA intervals, 60 CA intervals, 90 CA intervals, and 120 CA intervals.
- crank angle interval any other crank angle interval may be adopted as long as the above [Condition 1] and [Condition 2] are satisfied.
- ⁇ Average flow rate calculation process> a process for calculating an average value (average flow rate of intake air) of AFM data acquired by the AFM data acquisition process will be described with reference to a flowchart of FIG.
- the processing routine of FIG. 5 is repeatedly executed in the ECU 200 every predetermined time (for example, every 16 msec).
- step ST201 the engine speed is calculated from the output signal of the crank position sensor 25.
- step ST202 it is determined whether or not switching of the crank angle interval (CA interval) has occurred based on the engine speed calculated in step ST201.
- the engine speed of the previous routine is a value larger than 3800 rpm
- the engine speed of the current routine is also a value larger than 3800 rpm
- the CA It is determined that the interval has not been switched, and the process proceeds to step ST203.
- step ST203 the AFM data acquired in the AFM data acquisition process is averaged to calculate the average flow rate of the intake air.
- the average flow rate calculation process will be described later.
- step ST204 the average flow rate at the time of switching is calculated.
- the process of step ST204 is a process executed when the crank angle interval is switched, and after this process ends (after the average flow rate calculation process of one cycle of intake pulsation at the time of CA interval switching), Proceeding to step ST203, the average flow rate calculation process is repeated. Note that the processing in step ST204 (processing for calculating the average flow rate at the time of switching) will also be described later.
- the processing is performed at the same angular period as the pulsation period of the intake pulsation.
- the crank angle (720 °) per cycle is divided by the number of cylinders (a period corresponding to one cycle of intake pulsation).
- the average interval is 180 °
- the number of acquired data is 180 (30 ° / 30 °) when the crank angle interval is 30 CA (see FIG. 4).
- the number of acquired data when the crank angle interval is 60 CA intervals is 3 (180 ° / 60 °) (see FIG. 4)
- the number of acquired data when the crank angle interval is 90 CA intervals is 2 (180 (See FIG. 4).
- the crank angle interval is 120 CA intervals, the number of acquired data is one and the average value cannot be calculated. Therefore, for the 120 CA interval, the acquired interval is 360 °, which is a multiple of 180 °, and the number of acquired data is three. (See FIG. 4).
- step ST203 the AFM data stored in the buffer by the above-described AFM data acquisition process is monitored, the sum of a plurality of AFM data is calculated, and the calculated sum of the AFM data is divided by the number of acquired data.
- the average value of the AFM data that is, the average flow rate of the intake air is calculated.
- step ST202 determines whether the crank angle interval is 30 CA, as shown in FIG. 8, it is monitored whether the AFM data acquired by the AFM data acquisition process is stored in six 30 CA buffers. The total sum of the six AFM data is calculated, and the total sum of the calculated AFM data is divided by “6” to calculate the average flow rate of the intake air. Such a calculation process is sequentially repeated when the determination result in step ST202 is negative (NO) (when there is no CA interval switching). If the determination result in step ST202 is affirmative (YES), the process proceeds to step ST203 after executing the process in step ST204 (calculation of the average flow rate at the time of switching).
- the average flow rate of the intake air is calculated by the same processing. That is, when the crank angle interval is 60 CA, the average flow rate of the intake air is calculated by averaging three AMF data as shown in FIG. When the crank angle interval is 90 CA, the average flow rate of the intake air is calculated by averaging the two AMF data. When the crank angle interval is 120 CA, the average flow rate of the intake air is calculated by averaging the three AMF data.
- crank angle interval for acquiring the AFM signal when the crank angle interval for acquiring the AFM signal is switched, sampling at unequal intervals occurs within one cycle of the intake pulsation at the time of switching, and the average value of the AFM data varies. This will be described below. The description will be made separately for the case where the crank angle interval (CA interval) before and after the switching has a multiple relationship and the case where the crank angle interval (CA interval) before and after the switching has a non-multiple relationship.
- a process (average flow rate calculation process at the time of switching) for eliminating the fluctuation of the AFM data average value at the time of switching the CA period as described above will be described with reference to FIG.
- FIG. 8 shows an example in which the crank angle interval is switched from 30 CA intervals to 60 CA intervals.
- the AFM data [Da6] in the 30CA buffer and the AFM data [Db1] and [Db2] in the 60CA buffer are used.
- the average value is calculated, the AFM data average value fluctuates as described above.
- AFM data [Da5] that matches the 60CA interval is selected from the AFM data acquired at the 30CA interval, and the selected AFM data [Da5] is copied to the 60CA buffer to obtain the 60FM interval.
- an average value is calculated using the AFM data [Db3] subjected to the processing and the AFM data [Db1] and [Db2] acquired at 60 CA intervals.
- the process of calculating the AFM data average value using the AFM data [Da5] that coincides with the 60CA interval described above is “when the crank angle interval before and after switching is in a multiple relationship,” This is equivalent to “calculating the average value using sampling values acquired at a larger crank angle interval among the crank angle intervals”.
- AFM data acquired at 60 CA interval and AFM data obtained at 90 CA are mixed within one cycle of intake pulsation.
- the average value of the AFM data is calculated using the two AFM data acquired at the 60 CA interval. Also in this case, when the crank angle interval is switched, the average value of the AFM data may fluctuate for a moment, and the average value fluctuation may become noise.
- FIG. 10 shows an example in which the crank angle interval is switched from the 60 CA interval to the 90 CA interval.
- the crank angle interval and AFM data is acquired at 60 CA intervals by the above-described AFM data acquisition process
- the AFM data acquired every 60 CA intervals is sequentially stored in the 60 CA buffer in the ECU 200.
- an average value is calculated using the three AFM data.
- AFM data (AFM data that is not actually acquired) at a crank angle of 90 CA before the CA interval switching (270 ° CA in the example of FIG. 10) is obtained before and after the crank angle by 60 CA.
- AFM data (AFM data that is not actually acquired) at a crank angle of 90 CA before the CA interval switching (270 ° CA in the example of FIG. 10) is obtained before and after the crank angle by 60 CA.
- Calculated by linear interpolation using two AFM data [Db2] and [Db3] acquired at intervals, and averaged using the calculated AFM data [Dc2] and AFM data [Dc1] acquired at 90CA intervals Calculate the value.
- the average flow rate calculation process at the time of switching the CA interval is executed for one cycle of the intake pulsation at the time of switching.
- crank angle interval When the crank angle interval is switched from 90 CA interval to 120 CA interval (90 CA interval ⁇ 120 CA interval), when the crank angle interval is switched from 120 CA interval to 90 CA interval (120 CA interval ⁇ 90 CA interval), and crank angle interval is 90 CA interval.
- the variation of the AFM data average value can be suppressed by the same processing as described above.
- the processing of [Average value calculation processing example 2] described above is the “value obtained by performing linear interpolation on the two sampling values acquired at the crank angle interval before switching and the crank angle interval after switching” in the present invention.
- the average value is calculated using the sampling value acquired in step 1).
- processing is performed at the same angular cycle as the pulsation cycle of the intake pulsation, and the output signal (AFM signal) of the air flow meter 22 is sampled at equal intervals within one cycle of the intake pulsation. Therefore, the influence of the intake pulsation can be eliminated, and the fluctuation of the average value (average flow rate calculation value) of the AFM data can be suppressed. Moreover, since the crank angle interval for acquiring AFM data is increased when the engine speed (crankshaft speed) is high compared to when the engine speed is low, the ECU 200 The processing load (calculation load) does not increase.
- the crank angle interval for acquiring AFM data is increased, the calculation accuracy of the calculated average value of AFM data tends to deteriorate.
- the period of intake pulsation is also shortened.
- the output signal (AFM signal) of the air flow meter 22 is smoothed (the amplitude of the intake pulsation is reduced), the output signal of the air flow meter 22 is an average value compared to the case where the engine speed is in the low speed range. A value close to. Therefore, even if the crank angle interval for acquiring AFM data is increased, an error is less likely to occur.
- the present invention is not limited to this, and the intake air amount measurement processing of any other internal combustion engine such as a gasoline engine is performed.
- the present invention is also applicable.
- the present invention can be used for an intake air amount measuring device of an internal combustion engine (engine), and more specifically, an internal combustion engine that measures an intake air amount based on an output signal of an air flow meter disposed in an intake passage of the internal combustion engine. It can be effectively used for an intake air amount measuring device.
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Abstract
Description
本発明を適用するエンジン(内燃機関)の概略構成について図1を参照して説明する。なお、図1にはエンジンの1気筒の構成のみを示している。
エンジン1には、排気圧を利用して吸入空気を過給するターボチャージャ(過給機)100が装備されている。
また、エンジン1にはEGR装置5が装備されている。EGR装置5は、吸入空気に排気ガスの一部を導入することで、燃焼室1d内の燃焼温度を低下させてNOxの発生量を低減させる装置である。
ECU200は、図2に示すように、CPU(Central Processing Unit)201、ROM(Read Only Memory)202、RAM(Random Access Memory)203及びバックアップRAM204などを備えている。
次に、ECU200が実行するAFMデータ取得処理及び平均流量算出処理について説明する。
まず、AFMデータ取得処理の一例について、図3のフローチャートを参照して説明する。図3の処理ルーチンはECU200において所定時間ごと(例えば4msecごと)に繰り返して実行される。
次に、エアフロメータ22の出力信号をサンプリングするクランク角度間隔を設定する処理について説明する。
次に、上記AFMデータ取得処理で取得したAFMデータの平均値(吸入空気の平均流量)を算出する処理について、図5のフローチャートを参照して説明する。図5の処理ルーチンは、ECU200において所定時間ごと(例えば16msecごと)に繰り返して実行される。
次に、上記図5のステップST203において実行する「平均流量算出処理」について説明する。
次に、上記図5のステップST204において実行する「切り替え時における平均流量算出処理」について説明する。
クランク角度間隔を切り替えた際に、その切り替え前後のクランク角度間隔が倍数の関係にある場合(30CA⇒60CA)について図6を参照して説明する。
以上のような、CA期間切り替え時におけるAFMデータ平均値の変動を解消するための処理(切り替え時における平均流量算出処理)について図8を参照して説明する。なお、図8では、クランク角度間隔を30CA間隔から60CA間隔に切り替える場合の例を示している。
次に、クランク角度間隔を切り替えた際に、その切り替え前後のクランク角度間隔が非倍数の関係にある場合(60CA⇒90CA)について図9を参照して説明する。
以上のような、CA期間切り替え時におけるAFMデータ平均値の変動を解消するための処理(切り替え時における平均流量算出処理)について図10を参照して説明する。なお、図10では、クランク角度間隔を、60CA間隔から90CA間隔に切り替える場合の例を示している。
以上説明したように、本実施形態によれば、吸気脈動の脈動周期と同じ角度周期で処理を行い、その吸気脈動の1周期内においてエアフロメータ22の出力信号(AFM信号)を等間隔でサンプリングしているので、吸気脈動による影響を排除することができ、AFMデータの平均値(平均流量算出値)の変動を抑制することが可能になる。しかも、エンジン回転数(クランクシャフトの回転数)が高い場合は低い場合と比較して、AFMデータを取得するクランク角度間隔を大きくしているので、エンジン回転数が高回転となってもECU200の処理負荷(計算負荷)が増大することはない。
以上の実施形態では、4気筒ディーゼルエンジンの吸入空気量計測処理に本発明を適用した場合について説明した。本発明はこれに限られることなく、例えば6気筒ディーゼルエンジンなど他の任意の気筒数のディーゼルエンジンの吸入空気量計測処理にも適用可能である。
11 吸気通路
22 エアフロメータ
25 クランクポジションセンサ
200 ECU
Claims (8)
- 内燃機関の吸気通路に配置されたエアフロメータを備え、前記エアフロメータの出力信号に基づいて当該内燃機関の燃焼室への吸入空気量を計測する内燃機関の吸入空気量計測装置であって、
前記エアフロメータの出力信号を、前記内燃機関のクランク角度に同期してサンプリングすることを特徴とする内燃機関の吸入空気量計測装置。 - 請求項1記載の内燃機関の吸入空気量計測装置において、
前記エアフロメータの出力信号を、前記内燃機関のクランク角度に同期して所定のクランク角度間隔でサンプリングすることを特徴とする内燃機関の吸入空気量計測装置。 - 請求項2記載の内燃機関の吸入空気量計測装置において、
前記クランク角度間隔は、クランク角度360°を2以上の整数で割った値であり、かつ、前記内燃機関の1サイクルに対応するクランク角度を当該内燃機関の気筒数で割った値を除くクランク角度間隔であることを特徴とする内燃機関の吸入空気量計測装置。 - 請求項1~3のいずれか1つに記載の内燃機関の吸入空気量計測装置において、
前記エアフロメータの出力信号を、前記内燃機関のクランク角度に同期してサンプリングした複数のデータの平均値を算出して、吸入空気の平均流量を得ることを特徴とする内燃機関の吸入空気量計測装置。 - 請求項1~4のいずれか1つに記載の内燃機関の吸入空気量計測装置において、
前記エアフロメータの出力信号をサンプリングするクランク角度間隔を、前記内燃機関の機関回転数に応じて切り替えることを特徴とする内燃機関の吸入空気量計測装置。 - 請求項5記載の内燃機関の吸入空気量計測装置において、
前記内燃機関の機関回転数が高い場合は、当該機関回転数が低い場合に比べて、前記クランク角度間隔を大きく設定することを特徴とする内燃機関の吸入空気量計測装置。 - 請求項6記載の内燃機関の吸入空気量計測装置において、
前記クランク角度間隔を切り替える場合、その切り替え前後のクランク角度間隔が倍数の関係にあるときには、前記切り替え前後におけるクランク角度間隔のうち、大きい側のクランク角度間隔で取得したサンプリング値を用いて前記平均値を算出することを特徴とする内燃機関の吸入空気量計測装置。 - 請求項6記載の内燃機関の吸入空気量計測装置において、
前記クランク角度間隔を切り替える場合、その切り替え前後のクランク角度間隔が非倍数の関係にあるときには、前記切り替え前のクランク角度間隔で取得した2つのサンプリング値を線形補間をした値と、前記切り替え後のクランク角度間隔で取得したサンプリング値とを用いて前記平均値を算出することを特徴とする内燃機関の吸入空気量計測装置。
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JP2013552380A JP5920362B2 (ja) | 2012-01-06 | 2012-01-06 | 内燃機関の吸入空気量計測装置 |
PCT/JP2012/050200 WO2013103018A1 (ja) | 2012-01-06 | 2012-01-06 | 内燃機関の吸入空気量計測装置 |
US14/370,561 US9488140B2 (en) | 2012-01-06 | 2012-01-06 | Intake air volume measuring device for internal combustion engine |
CN201280066293.2A CN104040155B (zh) | 2012-01-06 | 2012-01-06 | 内燃机吸入空气量测量装置 |
EP12864512.4A EP2801715B1 (en) | 2012-01-06 | 2012-01-06 | Intake air volume measuring device for internal combustion engine |
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JP6540743B2 (ja) * | 2017-03-30 | 2019-07-10 | 株式会社デンソー | 空気量算出装置 |
CN108798922B (zh) * | 2017-04-27 | 2021-03-26 | 比亚迪股份有限公司 | 发动机空气流量的采样方法、系统及汽车 |
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