JP7052230B2 - Air flow rate measuring device and air flow rate measuring method - Google Patents

Description

The disclosure by this specification relates to an air flow rate measuring device and an air flow rate measuring method.

Conventionally, as an example of an air flow rate measuring device, there is a control device for an internal combustion engine disclosed in Patent Document 1. This control device calculates the pulsation amplitude ratio and the pulsation frequency, and calculates the pulsation error from the pulsation amplitude ratio and the pulsation frequency. Here, this control device calculates the rotation speed of the internal combustion engine using the signal from the crank angle sensor, and calculates the pulsation frequency using this rotation speed. Then, the control device refers to the correction coefficient required for correcting the pulsation error from the pulsation amplitude ratio and the pulsation frequency from the pulsation error correction map, and calculates the amount of air corrected for the pulsation error.

Japanese Unexamined Patent Publication No. 2014-20212

However, in Patent Document 1, the signal from the crank angle sensor is used for the calculation of the pulsation frequency, but if the signal contains disturbance such as noise, the calculation accuracy of the pulsation frequency is lowered. Is a concern. When the pulsation frequency cannot be stably acquired in this way, the correction error increases and the acquisition accuracy of the air amount also decreases.

A main object of the present disclosure is to provide an air flow rate measuring device capable of improving the measurement accuracy of the air flow rate.

In order to achieve the above object, the disclosed first aspect is
An air flow rate measuring device (26) that measures an air flow rate based on a detection value (Sa) detected by a sensing unit (25) according to an air flow.
A detection acquisition unit (35) that acquires a maximum value (Ap) or a minimum value (Au) of a detection value as a detection-related value for a predetermined specific period (Ts).
Attenuation acquisition unit (37) that acquires the maximum value (Bp) or the minimum value (Bu) of the attenuation value in a specific period as an attenuation-related value for the attenuation value (Sb) obtained by attenuated the detected value by a predetermined filter (36). When,
As the relation value (C) indicating the relationship between the detection-related value and the attenuation-related value, the relation acquisition unit (38) for acquiring the ratio between the detection-related value and the attenuation-related value or the difference between the detection-related value and the attenuation-related value. When,
The frequency acquisition unit (43) that acquires the pulsation frequency (F) of air using the relational value, and
A correction amount acquisition unit (44) that acquires a correction amount (Q) using the pulsation frequency, and
For a specific period, the difference between the maximum value of the detected value and the average value (Aa) of the detected value, the difference between the average value and the minimum value of the detected value, the difference between the maximum value of the detected value and the minimum value of the detected value, or An amplitude acquisition unit (42) that acquires an amplitude factor obtained by dividing the difference between the maximum value and the average value (Aa) of the detected values by the average value as an amplitude-related value.
Equipped with
The frequency acquisition unit estimates the pulsation frequency from the relational value and the amplitude-related value by using the frequency characteristic that specifies the relation between the relational value, the amplitude-related value, and the pulsation frequency.
It is an air flow rate measuring device that calculates the air flow rate by correcting the detected value using the correction amount.

The present inventor has found that there is a predetermined relationship between the pulsation frequency and the relational value indicating the relation between the detection-related value and the attenuation-related value. According to this finding, a configuration for estimating the pulsation frequency based on the relational value is realized as in the first aspect. In this case, since it is not necessary to use a differential operation to estimate the pulsation frequency, even if a disturbance such as noise is included in the detected value, it is possible to suppress that the estimation accuracy of the pulsation frequency is lowered due to the presence of the disturbance. .. Then, by using this pulsation frequency, the measurement accuracy of the air flow rate can be improved.

In addition, as a configuration in which the differential operation is used for estimating the pulsation frequency, for example, the timing at which the detected value switches from the increase to the decrease is acquired by the differential operation of the detected value, and the pulsating frequency is estimated based on the acquisition result. The configuration is mentioned. In this configuration, when the detected value increases as a whole while repeating small increase / decrease due to disturbance and reaches the maximum value, there is a concern that the maximum value of the small increase / decrease due to disturbance and the maximum value of the detected value cannot be discriminated. This is because the maximum value of the detected value due to the pulsation of air and the maximum value of the detected value due to the disturbance are the values at which the detected value switches from the increase to the decrease. As described above, when the differential operation of the detected value is used for estimating the pulsating frequency, the accuracy of estimating the pulsating frequency tends to decrease due to the existence of the maximum value of the detected value due to the disturbance.

The second aspect is
It is an air flow rate measuring method that measures an air flow rate based on a detection value (Sa) detected by a sensing unit (25) according to an air flow.
For a predetermined specific period (Ts), the maximum value (Ap) or the minimum value (Au) of the detected value is acquired as a detection-related value (35).
With respect to the attenuation value (Sb) in which the detected value is attenuated by a predetermined filter (36), the maximum value (Bp) or the minimum value (Bu) of the attenuation value in a specific period is acquired as an attenuation-related value (37).
As the relational value (C) indicating the relation between the detection-related value and the attenuation-related value, the ratio between the detection-related value and the attenuation-related value or the difference between the detection-related value and the attenuation-related value is acquired (38).
Obtain the air pulsation frequency (F) using the relational values (43),
Obtain the correction amount (Q) using the pulsation frequency (44 ),
For a specific period, the difference between the maximum value of the detected value and the average value (Aa) of the detected value, the difference between the average value and the minimum value of the detected value, the difference between the maximum value of the detected value and the minimum value of the detected value, or The amplitude factor obtained by dividing the difference between the maximum value and the average value (Aa) of the detected values by the average value is acquired as an amplitude-related value (42).
Estimate the pulsation frequency from the relational value and the amplitude-related value using the frequency characteristics that specify the relation between the relational value and the amplitude-related value and the pulsation frequency.
This is an air flow rate measurement method that calculates the air flow rate by correcting the detected value using the correction amount.

According to the second aspect, the same effect as that of the first aspect is obtained.

It should be noted that the scope of claims and the reference numerals in parentheses described in this section indicate the correspondence with the specific means described in the embodiment described later as one embodiment, and are the technical scope of the present disclosure. Is not limited to.

The block diagram which shows the schematic structure of the air flow meter and the ECU in 1st Embodiment. The schematic which shows the structure of the combustion system. The figure which shows the change mode of the detected value and the change mode of the attenuation value. The figure which shows the frequency characteristic. The block diagram which shows the structure of the pulsation estimation part. The figure which shows the frequency characteristic in 3rd Embodiment. The block diagram which shows the structure of the pulsation estimation part in 4th Embodiment. The block diagram which shows the structure of another pulsation estimation part. The block diagram which shows the structure of another pulsation estimation part. The block diagram which shows the structure of the pulsation estimation part in 5th Embodiment. The figure for demonstrating the setting of a specific period. The block diagram which shows the structure of the pulsation estimation part in 6th Embodiment. The block diagram which shows the structure of the flow rate correction part. The figure which shows the one-dimensional correction coefficient map in 7th Embodiment. The figure which shows the relationship between the pulsation amplitude and the pulsation error. The figure which shows the 2D correction coefficient map in 8th Embodiment. The figure which shows the 3D correction coefficient map in 9th Embodiment. The figure which shows the 3D correction coefficient map in 10th Embodiment. The figure which shows the relationship between the pulsation amplitude and the pulsation error in eleventh embodiment. The figure which shows the correction coefficient map. The figure which shows the relationship between the pulsation amplitude and the pulsation error in the twelfth embodiment. The figure which shows the correction coefficient map.

Hereinafter, a plurality of embodiments of the present disclosure will be described with reference to the drawings. By assigning the same reference numerals to the corresponding components in each embodiment, duplicate description may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. Further, not only the combination of the configurations specified in the description of each embodiment but also the configurations of a plurality of embodiments can be partially combined even if the combination is not specified. Further, an unspecified combination of the configurations described in the plurality of embodiments and modifications is also disclosed by the following description.

(First Embodiment)
The combustion system 10 shown in FIG. 2 includes an internal combustion engine 11 such as a diesel engine, an intake passage 12, an exhaust passage 13, an air cleaner 14, an air flow meter 15, and an ECU 20, and is mounted on, for example, a vehicle. The air flow meter 15 is provided in the intake passage 12, and has a function of measuring physical quantities such as the flow rate, temperature, and humidity of the intake air supplied to the internal combustion engine 11. The air flow meter 15 corresponds to a physical quantity measuring device for measuring intake air as a fluid. The intake air is air supplied to the combustion chamber 11a of the internal combustion engine 11 and corresponds to a gas. The intake air can also be referred to as intake air.

The air flow meter 15 is attached to an intake pipe 12a forming an intake passage 12 on the downstream side of the air cleaner 14. The air cleaner 14 has an element 14a for removing foreign matter mixed in the intake air, and the intake air cleaned by the air cleaner 14 reaches the air flow meter 15. The element 14a is made of a filter medium such as a synthetic fiber non-woven fabric or a filter paper.

The ECU (Engine Control Unit) 20 shown in FIGS. 1 and 2 is a control device that controls the operation of the combustion system 10. The ECU 20 has a computer configured to include a processor 20a, a storage unit 20b, an input / output interface, and the like. Examples of the storage unit 20b include a storage medium such as a RAM. In the ECU 20, a program for controlling the operation of the combustion system 10 is stored in a storage unit 20b or the like, and this program is executed by the processor 20a. The ECU 20 performs engine control such as control of the opening degree of the throttle valve 17 and control of the fuel injection amount of the injector 18 by using the measurement result by the air flow meter 15. Therefore, the ECU 20 can be referred to as an engine control device, and the combustion system 10 can also be referred to as an engine control system.

The combustion system 10 includes an EGR system (not shown). The EGR valve included in this EGR system is electrically connected to the ECU 20, and the ECU 20 also controls the operation of the EGR valve.

The air flow meter 15 is one of a plurality of measuring units included in the combustion system 10, and a plurality of measuring units including the air flow meter 15 are electrically connected to the ECU 20. Examples of these measurement units include an air-fuel ratio sensor 21, a crank angle sensor 22, a cam angle sensor 23, and the like, and these sensors 21 to 23 output detection signals to the ECU 20, respectively. The air-fuel ratio sensor 21 is provided in the exhaust system of the internal combustion engine 11 and detects the air-fuel ratio of the exhaust gas flowing through the exhaust passage 13. The crank angle sensor 22 is attached to, for example, a cylinder block, and detects the rotation angle of the crankshaft. The cam angle sensor 23 is attached to, for example, a cylinder head, and detects the rotation angle of the camshaft. The ECU 20 acquires the engine speed by using the detection signals of the crank angle sensor 22 and the cam angle sensor 23.

When the flow rate of the intake air in the intake passage 12 is referred to as an air flow rate, the air flow meter 15 measures the air flow rate based on the sensing unit 25 that outputs a detection signal according to the air flow rate and the detection signal from the sensing unit 25. It has a processing unit 26 for processing.

The air flow meter 15 has a bypass flow path that takes in a part of the intake air flowing through the intake passage 12, and the sensing unit 25 is provided in this bypass flow path. In this case, the sensing unit 25 is provided so as to come into contact with the intake air in an environment in which the intake air flows. The sensing unit 25 is electrically connected to the processing unit 26, and outputs a detection signal according to the flow velocity and the flow rate of the intake air in the bypass flow path to the processing unit 26. This detection signal can also be referred to as an output signal. The sensing unit 25 is a thermal sensor element having a heat generation resistor, a resistance temperature detector, and the like, and can also be referred to as a flow rate detection unit. In the present embodiment, the bypass flow path has a passing flow path through which the intake air passes and a branch flow path branched from the passing flow path, and the sensing unit 25 is provided in the branch flow path.

Like the ECU 20, the processing unit 26 has a computer configured including a processor 26a, a storage unit 26b, an input / output interface, and the like, and is electrically connected to the ECU 20. Examples of the storage unit 26b include a storage medium such as a RAM. In the processing unit 26, a program for measuring the air flow rate is stored in the storage unit 26b or the like, and this program is executed by the processor 26a. The processing unit 26 corresponds to an air flow rate measuring device and outputs information regarding the measured air flow rate to the ECU 20.

In the intake air flowing through the intake passage 12, pulsation including backflow is generated due to the reciprocating motion of the piston in the internal combustion engine 11. When this pulsation is referred to as an intake pulsation, the detection signal of the sensing unit 25 is affected by the intake pulsation and includes an error with respect to the true air flow rate. In particular, the sensing unit 25 is more susceptible to intake pulsation when the throttle valve is operated to the fully open side. Here, the true air flow rate is an air flow rate that is not affected by the inspiratory pulsation.

The present inventor obtains a relational value indicating the relationship between the detected value detected by the sensing unit 25 and the attenuation value obtained by attenuated the detected value by the filtering process, and the pulsating frequency of the relational value and the detected value is obtained. It was found that there is a predetermined relationship with. According to this finding, the pulsation frequency can be estimated by using the relational value indicating the relation between the detected value and the attenuation value. Here, the detected value is a numerical value of the detection signal from the sensing unit 25, and can be said to be a value indicating the air flow rate before correction acquired based on the detection signal. Further, the pulsation frequency is the frequency of the pulsation included in the detected vibration, and is also the frequency of the inspiratory pulsation.

In the present embodiment, the maximum value included in each of the detected value and the attenuation value is referred to as a detection peak value and an attenuation peak value, and the relationship between these detected peak values and the attenuation peak value is acquired . For example, regarding the detection value Sa shown in FIG. 3, the maximum value in the predetermined specific period Ts is referred to as the detection peak value Ap, and the minimum value in the specific period Ts is also referred to as the detection bottom value Au, which is also the specific period. The average value in Ts is referred to as the detected average value Aa. In this case, when the amplitude of the pulsation included in the detected value Sa in the specific period Ts is referred to as the detected amplitude Am, this detected amplitude Am is calculated as the difference between the detected peak value Ap and the detected average value Aa. This relationship can also be expressed by the mathematical formula Aam = Ap-Aa.

The detected peak value Ap is a value indicating the maximum flow rate, the detected bottom value Au is a value indicating the minimum flow rate, and the detected average value Aa is a value indicating the average flow rate. All of these values are values for the air flow rate before correction. Further, the detection peak value Ap corresponds to the detection-related value.

Regarding the attenuation value Sb shown in FIG. 3, the maximum value in the specific period Ts is referred to as the attenuation peak value Bp, and the minimum value in the specific period Ts is also referred to as the attenuation bottom value Bu, as in the case of the detected value Sa. The average value in the specific period Ts is referred to as an attenuation average value Ba. In this case, when the amplitude of the pulsation included in the attenuation value Sb in the specific period Ts is referred to as the attenuation amplitude Bam, this attenuation amplitude Bam is calculated as the difference between the attenuation peak value Bp and the attenuation average value Ba. This relationship can also be expressed by the mathematical formula Bam = Bp-Ba.

The detected peak value Ap, the detected bottom value Au, the attenuation peak value Bp, and the attenuation bottom value Bu are all set to zero as a reference value. In this embodiment, the detected bottom value Au is zero. In this case, it can be said that the detected peak value Ap, the attenuation peak value Bp, and the attenuation bottom value Bu are values based on the detected bottom value Au. Further, the attenuation peak value Bp corresponds to the attenuation-related value.

In the present embodiment, as the relational value indicating the relationship between the detected value Sa and the attenuation value Sb, the relational value C indicating the relationship between the detected peak value Ap and the attenuation peak value Bp is used . The ratio obtained by dividing the attenuation peak value Bp by the detected peak value Ap is defined as the relation value C. This relationship can also be expressed by the mathematical formula C = Bp / Ap. In the drawings such as FIG. 4, the relational value C is described as the comparative value C.

Regarding the pulsating frequency F included in the detected value Sa, as a method of acquiring the pulsating frequency F, a method of performing a differential operation of the detected value Sa to acquire the peak timing at which the detected value Sa switches from an increase to a decrease is obtained. Can be mentioned. However, in this method, if the detected value Sa includes a disturbance such as noise, there is a concern that the detected value Sa may be erroneously recognized as a small peak due to the disturbance and a large peak due to the inspiratory pulsation. In this case, instead of acquiring the pulsation frequency F for the inspiratory pulsation, the pulsation frequency is acquired for the disturbance.

On the other hand, the present inventor newly created a frequency characteristic so that the pulsating frequency F can be specified without performing a differential operation. In the frequency characteristics, the relationship between the relational value C , the detection amplitude Aam, and the pulsation frequency F is specified, and by using this frequency characteristic, the pulsation frequency F is estimated based on the relational value C and the detection amplitude Aam. Can be done.

In this embodiment, the frequency characteristics are mapped, and this map is referred to as a pulsation map. In the pulsation map shown in FIG. 4, the horizontal axis indicates the detection amplitude Am, the vertical axis indicates the relation value C , and further, the frequency line showing the relationship between the detection amplitude Aam, the relation value C , and the pulsation frequency F is shown. ing. In this pulsation map, when the relation value C and the detection amplitude Am are plotted for the detection value Sa, this plot position indicates the pulsation frequency F of the detection value Sa. For example, when the detection amplitude Am is X and the relation value C is Y, it indicates that the pulsation frequency F is 80 [Hz].

The processing unit 26 performs pulsation estimation processing for estimating the pulsation frequency F with respect to the detected value Sa. The processing unit 26 has a function of executing a pulsation estimation process, and this function is referred to as a pulsation estimation unit 30. The pulsation estimation unit 30 shown in FIG. 5 has a plurality of functions for executing a plurality of processes included in the pulsation estimation process. In the processing unit 26, the procedure of the pulsation estimation processing executed by the pulsation estimation unit 30 corresponds to the air flow rate measuring method.

The pulsation estimation unit 30 includes a signal acquisition unit 31, a period setting unit 32, a detection peak acquisition unit 35, a filter unit 36, an attenuation peak acquisition unit 37, a relationship acquisition unit 38 , an average acquisition unit 41, an amplitude acquisition unit 42, and a frequency acquisition unit. It has 43 and a correction amount acquisition unit 44. The processing unit 26 outputs information regarding the estimated pulsation frequency F to the ECU 20. In the drawings such as FIG. 5, the relationship acquisition unit 38 is described as the comparison unit 38.

In the pulsation estimation unit 30, the signal acquisition unit 31 acquires the detection value Sa detected by the sensing unit 25 by acquiring the detection signal from the sensing unit 25. The period setting unit 32 sets a period having a predetermined length as a specific period Ts. Here, information about the pulsation frequency F estimated by the past pulsation estimation unit 30 is stored in the storage unit 26b, this information is read from the storage unit 26b, and the specific period Ts is set based on this information. For example, the value acquired by the pulsation estimation unit 30 as the specific period Ts in the previous process is set in the specific period Ts in the current process. The detection peak acquisition unit 35 acquires the detection peak value Ap in the specific period Ts for the detection value Sa. The detection peak acquisition unit 35 corresponds to the detection acquisition unit.

The filter unit 36 is a filter that performs a filter process on the detected value Sa, and acquires the attenuation value Sb as a result of the filter process. Here, as the filter processing, the first-order lag system is smoothed for the detected value Sa. This smoothing process can also be referred to as an attenuation process for attenuating the first-order lag system. In this smoothing process, for example, y (t) of the mathematical formula shown in the filter unit 36 of FIG. 5 is acquired as the attenuation value Sb. In this formula, T is a time constant.

The attenuation peak acquisition unit 37 acquires the attenuation peak value Bp in the specific period Ts for the attenuation value Sb. The attenuation peak acquisition unit 37 corresponds to the attenuation acquisition unit. The relationship acquisition unit 38 calculates the ratio between the detection peak value Ap acquired by the detection peak acquisition unit 35 and the attenuation peak value Bp acquired by the attenuation peak acquisition unit 37, and acquires this calculation result as the relationship value C.

The average acquisition unit 41 acquires the detected average value Aa for the detected value Sa. The amplitude acquisition unit 42 acquires the detection amplitude Am by using the detection peak value Ap acquired by the detection peak acquisition unit 35 and the detection average value Aa acquired by the average acquisition unit 41.

The frequency acquisition unit 43 acquires the pulsating frequency F by using the relation value C acquired by the relationship acquisition unit 38 and the detection amplitude Am acquired by the amplitude acquisition unit 42. Here, a pulsation map as shown in FIG. 4 is stored in the storage unit 26b, and the frequency acquisition unit 43 reads the pulsation map from the storage unit 26b and acquires the pulsation frequency F using this pulsation map. Specifically, the relational value C and the detection amplitude Am are plotted, and the frequency line closest to this plot position among the plurality of frequency lines is acquired as the pulsating frequency F.

The correction amount acquisition unit 44 acquires the correction amount Q of the detected value Sa using the pulsation frequency F. Here, in addition to the pulsation frequency F, the correction amount Q is calculated using the detection peak value Ap, the detection amplitude Am, and the like. The correction amount Q is acquired for a plurality of timings in a specific period Ts. When the signal having information about the continuous change of the correction amount Q is referred to as the correction signal Sq for the specific period Ts, the corrected signal Sqa can be acquired by correcting the detection value Sa with the correction signal Sq. The correction amount Q corresponds to the correction value and the correction result.

The pulsation estimation unit 30 has a correction unit that corrects the detected value Sa using the correction amount Q. This correction unit acquires the corrected signal Sqa after the correction amount acquisition unit 44 acquires the correction amount Q, and calculates the air flow rate using the corrected signal Sqa. Can approach the air flow rate. If the characteristic of the pulsation of the air flow rate is referred to as the pulsation characteristic, the correction unit corrects the pulsation characteristic by using the correction amount Q. Further, the correction amount acquisition unit 44 and the correction unit constitute the detection correction unit.

According to the present embodiment described so far, when the pulsation frequency F is estimated, the relationship between the detected peak value Ap and the attenuation peak value Bp is acquired, so that it is not necessary to perform the differential operation of the detected value Sa. Therefore, it is possible to avoid erroneous recognition of the peak of the detected value Sa due to the inspiratory pulsation and the peak of the detected value Sa due to the disturbance by performing the differential operation of the detected value Sa. Therefore, even if the detected value Sa includes a disturbance, it is possible to suppress that the estimation accuracy of the pulsation frequency F is lowered due to the presence of the disturbance.

Further, since the relational value C is used for estimating the pulsation frequency F, it is not necessary to use the engine control information such as the engine speed acquired by the ECU 20. That is, it is not necessary to perform the pulsation estimation process for estimating the pulsation frequency F in the ECU 20. In this way, by performing the pulsation estimation processing in the processing unit 26 of the air flow meter 15, the processing load of the ECU 20 can be reduced. Further, since it is not necessary for the ECU 20 to output engine control information such as the engine speed to the processing unit 26 in order to realize a configuration in which the processing unit 26 estimates the pulsation frequency F, the ECU 20 performs information output processing. As for what to do, the processing load can be reduced.

Further, information including the pulsation frequency F acquired by the processing unit 26 is input to the ECU 20. In this case, the ECU 20 can detect the occurrence of an abnormality in the combustion system 10 by comparing the engine rotation frequency indicated by the engine rotation speed acquired by itself with the pulsation frequency F input from the processing unit 26. become. Examples of this abnormality include cylinder stop, valve timing abnormality, valve lift amount abnormality, EGR valve failure, and the like. Further, in a configuration in which the combustion system includes a turbocharger, a phenomenon called surging generated in the turbocharger can also be mentioned as the above abnormality.

According to the present embodiment, since the detection amplitude Am is used in addition to the relational value C for the estimation of the pulsation frequency F, there is a predetermined relationship between the relational value C , the detection amplitude Aam, and the pulsation frequency F. It is possible to improve the estimation accuracy of the pulsation frequency F by utilizing the knowledge of the present inventor. Moreover, since the frequency characteristic indicating the mutual relationship between the relational value C , the detected amplitude Aam, and the pulsating frequency F is used for the estimation of the pulsating frequency F, the pulsating frequency F is determined based on the relational value C and the detected amplitude Aam. It can be estimated with high accuracy.

According to the present embodiment, in the frequency characteristics, when the detection amplitude Am is a predetermined value, the larger the relational value C , the smaller the pulsating frequency F. Here, the fact that the relation value C is large means that the ratio of the attenuation peak value Bp to the detection peak value Ap is large, that is, the difference between the detected peak value Ap and the attenuation peak value Bp is small. Therefore, the estimation accuracy of the pulsation frequency F can be improved by utilizing the relationship that the smaller the difference between the detected peak value Ap and the attenuation peak value Bp, the smaller the pulsation frequency F.

According to the present embodiment, the relational value C is the ratio of the attenuation peak value Bp to the detected peak value Ap. In this case, even if the attenuation peak value Bp is larger than the detected peak value Ap, the relational value C is not a negative value but a value larger than "1". Therefore, assuming that the attenuation peak value Bp becomes the detected peak value Ap due to the occurrence of some abnormality, the occurrence of the abnormality can be grasped because the relational value C becomes larger than "1". In other words, it is possible to grasp the occurrence of an abnormality without assuming that the relational value C becomes negative.

According to the present embodiment, when the relational value C is acquired, the detection peak value Ap and the attenuation peak value Bp are used as items having a common element of the maximum value in the specific period Ts. Therefore, these detection peaks are used. The relationship between the value Ap and the attenuation peak value Bp can be properly acquired . Moreover, as long as one condition of Ts for a specific period is common, the detected peak value Ap and the attenuation peak value Bp can be easily obtained by simply detecting the magnitudes of each of the detected value Sa and the attenuation value Sb. Can be done. Therefore, it is possible to reduce the processing load on the processing unit 26 when acquiring the relational value C.

According to the present embodiment, since the specific period Ts is set by the period setting unit 32, it is possible to select a value as close as possible to the pulsation frequency F as the specific period Ts. Therefore, the estimation accuracy of the pulsation frequency F can be optimized. For example, if the specific period Ts is shorter than the pulsation frequency F, there is a concern that the peak in which the detected value Sa switches from increasing to decreasing is not included in the specific period Ts, and a non-peak value is selected as the detected peak value Ap. .. On the other hand, if the peak in which the attenuation value Sb switches from increase to decrease is included in the specific period Ts, the peak value is selected as the attenuation peak value Bp for the attenuation value Sb, and the relation value C. The calculation accuracy of the pulsation frequency F and the estimation accuracy of the pulsation frequency F are lowered.

According to the present embodiment, since the estimation accuracy of the pulsation frequency F is improved by using the relational value C , the measurement accuracy of the air flow rate corrected by using the pulsation frequency F can be improved.

(Second Embodiment)
In the first embodiment, the frequency line indicating the pulsation frequency F is shown in the pulsation map showing the frequency characteristics, but in the second embodiment, the frequency area showing the pulsation frequency F is shown in the pulsation map. In this embodiment, the differences from the first embodiment will be mainly described.

In the pulsation map shown in FIG. 6, a plurality of frequency areas show the relationship between the detection amplitude Am, the relation value C , and the pulsation frequency F. For example, the plurality of frequency areas include the first area AR1 and the second area AR2, the first area AR1 indicates that the pulsation frequency F is 100 [Hz], and the second area AR2 is. It is shown that the pulsation frequency F is 60 [Hz]. In this pulsation map, when the relational value C and the detection amplitude Am are plotted for the detected value Sa, the frequency area including the plotted position indicates the pulsating frequency F. For example, when the detection amplitude Am is X1 and the relational value C is Y1, it indicates that the pulsation frequency F is 100 [Hz]. Further, when the detection amplitude Am is X2 and the relational value C is Y2, it indicates that the pulsation frequency F is 60 [Hz].

According to the present embodiment, since a plurality of frequency areas are arranged in the pulsation map, the detected value Sa is determined by determining in which frequency area the plot position of the relational value C and the detected amplitude Aam is included. The pulsation frequency F can be estimated for. Therefore, unlike the pulsation map in which a plurality of frequency lines are shown as in the first embodiment, it is not necessary to perform a determination process of which frequency line the plot position is closest to. Therefore, it is possible to reduce the processing load when estimating the pulsation frequency F.

(Third Embodiment)
In the first embodiment, the pulsation frequency F is estimated using a pulsation map that maps the frequency characteristics, but in the third embodiment, the pulsation frequency F is estimated using a mathematical formula that formulates the frequency characteristics. In this embodiment, the differences from the first embodiment will be mainly described.

The mathematical formula used for estimating the pulsation frequency F defines the relationship between the relation value C , the detection amplitude Am, and the pulsation frequency F, and is represented by, for example, fa = F (C, Aam). By using this formula, the pulsation frequency F is calculated. In this way, when the frequency characteristics are mathematically expressed, the frequency acquisition unit 43 acquires the pulsating frequency F by simply performing the calculation of the mathematical expression, so that the processing load on the processing unit 26 can be reduced. It will be possible.

The pulsating frequency may be estimated using the coefficient converted into a coefficient. Further, for the acquisition of the pulsation frequency F, both the mapped frequency characteristic and the mathematical formula or the coefficiented frequency characteristic may be used. For example, the frequency acquisition unit 43 estimates the pulsating frequency F as the first estimated value using the pulsation map, estimates the pulsating frequency F as the second estimated value using the mathematical formula, and further estimates these first estimated values and the first. 2 The configuration is such that the average value with the estimated value is acquired as the pulsation frequency F.

(Fourth Embodiment)
In the first embodiment, the correction amount acquisition unit 44 acquires the correction amount Q using the pulsation frequency F, but in the fourth embodiment, the correction amount acquisition unit 44 obtains other parameters in addition to the pulsation frequency F. The correction amount Q is acquired by using. In this embodiment, the differences from the first embodiment will be mainly described.

For example, the correction amount acquisition unit 44 shown in FIG. 7 acquires the correction amount Q based on the detection amplitude Am acquired by the amplitude acquisition unit 42 in addition to the pulsation frequency F acquired by the frequency acquisition unit 43. With this configuration, it is possible to correct the pulsation characteristics that depend on the pulsation frequency F and the detection amplitude Am. In other words, the degree to which the correction process of the detection value Sa by the correction unit depends on the pulsation frequency F can be reduced by the detection amplitude Am.

Further, the correction amount acquisition unit 44 shown in FIG. 8 acquires the correction amount Q based on the detected average value Aa acquired by the average acquisition unit 41 in addition to the pulsation frequency F acquired by the frequency acquisition unit 43. In this configuration, the pulsating characteristic depending on the pulsating frequency F and the detected average value Aa can be corrected. In other words, the degree to which the correction process of the detected value Sa by the correction unit depends on the pulsating frequency F can be reduced by the detected average value Aa.

Further, the correction amount acquisition unit 44 shown in FIG. 9 has the detection amplitude Aam acquired by the amplitude acquisition unit 42 and the detection average value Aa acquired by the average acquisition unit 41 in addition to the pulsation frequency F acquired by the frequency acquisition unit 43. Based on this, the correction amount Q is acquired. In this configuration, it is possible to correct the pulsating characteristics that depend on the pulsating frequency F, the detected amplitude Aam, and the detected average value Aa. In other words, the degree to which the correction process of the detection value Sa by the correction unit depends on the pulsation frequency F can be reduced by the detection amplitude Am and the detection average value Aa.

(Fifth Embodiment)
In the first embodiment, the pulsation estimation unit 30 does not update the specific period Ts, but in the fifth embodiment, the specific period Ts is updated according to the estimated pulsation frequency F. In this embodiment, the differences from the first embodiment will be mainly described.

As shown in FIG. 10, the pulsation estimation unit 30 has a period update unit 47 that updates Ts for a specific period. The period update unit 47 estimates the pulsation cycle, which is the cycle of the inspiratory pulsation, using the pulsation frequency F acquired by the frequency acquisition unit 43, and updates the specific period Ts using this pulsation cycle. Specifically, the reciprocal of the pulsation frequency F is acquired as the pulsation cycle, and the value of the pulsation cycle is set to the specific period Ts.

The period update unit 47 assigns the information obtained by updating the specific period Ts to the detection peak acquisition unit 35, the attenuation peak acquisition unit 37, and the average acquisition unit 41. When the pulsation estimation unit 30 estimates the pulsation frequency F for the first time in the pulsation estimation process, the update information of the specific period Ts is not given to the acquisition units 35, 37, 41 and is set by the period setting unit 32. The value of Ts for a specific period is used. However, after the pulsation frequency F is estimated once, the acquisition units 35, 37, and 41 are updated by the period update unit 47 instead of using the values set by the period setting unit 32 as the specific period Ts. The value is used as Ts for a specific period.

For example, if the specific period Ts set by the period setting unit 32 is referred to as the first period Ts1 (see FIG. 11), the pulsation estimation unit 30 determines the specific period Ts when the pulsation frequency F is estimated for the first time. The first period Ts1 is used as. Then, the period update unit 47 assigns the second period Ts2 (see FIG. 11), which is the reciprocal of the pulsation frequency F estimated at the first time, to the acquisition units 35, 37, 41 as the specific period Ts. In this case, the detection peak acquisition unit 35, the attenuation peak acquisition unit 37, and the average acquisition unit 41 each acquire the detection peak value Ap, the attenuation peak value Bp, and the detection average value Aa using the second period Ts2.

According to the present embodiment, since the specific period Ts is updated using the estimation result of the pulsation frequency F, the inspiratory pulsation gradually changes so that the amplitude and cycle of the inspiratory pulsation gradually increase or decrease. Even so, the pulsation frequency F can be estimated accurately. This is because when the specific period Ts is set to a value substantially the same as the actual cycle of the inspiratory pulsation, the detected peak value Ap, the detected average value Aa, and the like can be accurately acquired. For example, unlike the present embodiment, if the specific period Ts is too short or too long with respect to the actual cycle of the inspiratory pulsation, the detected peak value Ap and the detected average value Aa cannot be accurately obtained. There is a concern that the estimation accuracy of the pulsation frequency F will decrease.

(Sixth Embodiment)
In the sixth embodiment, the pulsation estimation unit 30 has a flow rate correction unit 49. In this embodiment, the differences from the first embodiment will be mainly described. The pulsation estimation unit 30 shown in FIG. 12 has a flow rate correction unit 49 in place of the correction amount acquisition unit 44, and the flow rate correction unit 49 has a plurality of functions for executing a plurality of processes. The flow rate correction unit 49 corresponds to the detection correction unit.

The flow rate correction unit 49 shown in FIG. 13 has a pre-correction acquisition unit 50 that acquires the air flow rate before correction. The pre-correction acquisition unit 50 includes an A / D conversion unit 51, a sampling unit 52, and a first conversion table 53. The A / D conversion unit 51 A / D-converts the detected value Sa detected by the sensing unit 25 to acquire a digital value. The sampling unit 52 samples the digital value, and the first conversion table 53 converts the digital value into an air flow rate. In this way, the pre-correction acquisition unit 50 acquires the air flow rate before correction.

Further, the flow rate correction unit 49 includes an amplification unit 55, a second conversion table 56, a sampling storage unit 57, an amplitude calculation unit 58, a pulsation error calculation unit 61, and a pulsation correction unit 62. The amplification unit 55 uses the pulsating frequency F acquired by the frequency acquisition unit 43 to amplify the digital value attenuated by the A / D conversion unit 51, thereby returning the value to the value before attenuation. The second conversion table 56 converts the digital value amplified by the amplification unit 55 into an air flow rate in the same manner as in the first conversion table 53. The sampling storage unit 57 stores the air flow rate converted by the second conversion table 56. The amplitude calculation unit 58 reads the maximum value, the minimum value, and the average value of the air flow rate for the specific period Ts from the sampling storage unit 57, and calculates the pulsation amplitude ratio using these values.

The pulsation error calculation unit 61 estimates the pulsation error using the pulsation frequency F acquired by the frequency acquisition unit 43 and the pulsation amplitude ratio calculated by the amplitude calculation unit 58. Then, the pulsation correction unit 62 corrects the pulsation error so that the pulsation error becomes small by using the pulsation error calculated by the pulsation error calculation unit 61 and the uncorrected air flow rate acquired by the pre-correction acquisition unit 50. By doing so, the corrected air flow rate is acquired.

(7th Embodiment)
In the seventh embodiment, the error of the air flow rate due to the intake pulsation is referred to as a pulsation error Err [%], and the correction amount acquisition unit 44 calculates the pulsation error Err. In this embodiment, the differences from the first embodiment will be mainly described. Here, the detected mean value Aa is referred to as an average flow rate G [g / s], and the detected amplitude Am is referred to as a pulsating amplitude A. Further, as shown in FIG. 9 of the fourth embodiment, the correction amount acquisition unit 44 predicts the pulsation error Err using the average flow rate G, the detection amplitude Am, and the pulsation frequency F.

The correction amount acquisition unit 44 calculates the slope Ann and the intercept Bnn based on the average flow rate G and the pulsation frequency F, and calculates the pulsation error Err as a predicted value based on the pulsation amplitude A in addition to the slope Ann and the intercept Bnn. .. For example, the correction amount acquisition unit 44 uses the correction coefficient map shown in FIG. 14 when calculating the slope Ann based on the average flow rate G and the pulsation frequency F. This correction coefficient map is a one-dimensional map showing the relationship between the average flow rate G, the pulsation frequency F, and the slope Ann. In this one-dimensional map, G1 to Gn are arranged as the average flow rate G on the vertical axis, and F1 to Fn are arranged as the pulsating frequency F on the horizontal axis. As the slope Ann, A11 to Ann are arranged corresponding to the average flow rate G and the pulsation frequency F.

It should be noted that this correction coefficient map was created using data obtained by experiments or the like, and is stored in advance in the storage unit 26b or the like. Further, the intercept Bnn is also calculated using a map in the same manner as the slope Ann.

The correction amount acquisition unit 44 uses the following (Equation 1) as an error prediction formula when calculating the pulsation error Err based on the slope Ann, the intercept Bnn, and the pulsation amplitude A.
Err = Ann × A + Bnn ... (Equation 1)

The slope Ann is a value that depends on the pulsation amplitude A, and is a value that is changed for each of the average flow rate G and the pulsation frequency F as shown in the correction coefficient map.

As shown in FIG. 15, with respect to the correction value shown by the solid line and the pulsation characteristic shown by the broken line, the pulsation error Err increases as the pulsation amplitude A increases. In FIG. 15, the horizontal axis is the pulsation amplitude A, and the vertical axis is the pulsation error Err.

(8th Embodiment)
In the seventh embodiment, a one-dimensional map is used as the correction coefficient map, but in the eighth embodiment, a two-dimensional map is used. In this embodiment, the differences from the seventh embodiment will be mainly described. The correction coefficient map shown in FIG. 16 is a two-dimensional map showing the relationship between the average flow rate G, the pulsation frequency F, the slope Ann, and the intercept Bnn. In this two-dimensional map, the slope Ann and the intercept Bnn are associated with each other as a pair corresponding to the combination of the average flow rate G and the pulsation frequency F.

In the two-dimensional correction coefficient map, the vertical axis is the average flow rate G and the horizontal axis is the pulsation frequency F, as in the one-dimensional map of the seventh embodiment. As the slope Ann and the intercept Bnn, A11, B11 to Ann, and Bnn are arranged corresponding to the average flow rate G and the pulsation frequency F. Further, the correction amount acquisition unit 44 uses the above (Equation 1) when calculating the pulsation error Err, as in the above-mentioned seventh embodiment.

(9th Embodiment)
In the eighth embodiment, a two-dimensional map is used as the correction coefficient map, but in the ninth embodiment, a three-dimensional map is used. In this embodiment, the differences from the eighth embodiment will be mainly described. The correction coefficient map shown in FIG. 17 is a three-dimensional map showing the relationship between the average flow rate G, the pulsation frequency F, the correction amount Q, and the pulsation amplitude A. In this three-dimensional map, a plurality of two-dimensional maps showing the relationship between the average flow rate G, the pulsation frequency F, and the correction amount Q are provided for each pulsation amplitude A. In this case, the three-dimensional correction coefficient map has a plurality of two-dimensional correction coefficient maps.

In the two-dimensional correction coefficient map, the vertical axis and the horizontal axis are the same as those of the quadratic map of the eighth embodiment, and the pulsation amplitudes A1 to An are individually provided. For example, in the two-dimensional correction coefficient map for the pulsation amplitude A1, Q111 to Q1nn are arranged as the correction amount Q corresponding to the average flow rate G and the pulsation frequency F. Further, in the two-dimensional correction coefficient map for the pulsation amplitude An, Qn11 to Qnnn are arranged as the correction amount Q.

The correction amount acquisition unit 44 uses the following (Equation 2) as a regression equation when calculating the correction amount Q based on the average flow rate G, the pulsation frequency F, and the pulsation amplitude A.
Q = αG + βF + γA ... (Equation 2)

In this (Equation 2), α, β, and γ are all constants.

(10th Embodiment)
In the ninth embodiment, the parameters of the three-dimensional map are the average flow rate G, the pulsation frequency F, the correction amount Q and the pulsation amplitude A, but in the tenth embodiment, instead of the correction amount Q and the pulsation amplitude A, Inclination Ann, intercept Bnn and duct diameter D are included in the parameters. In this embodiment, the differences from the ninth embodiment will be mainly described.

In the three-dimensional correction coefficient map shown in FIG. 18, a plurality of two-dimensional maps showing the relationship between the average flow rate G, the pulsation frequency F, the slope Annnn, and the intercept Bnnnn are provided for each duct diameter D. The duct diameter D is the inner diameter of the intake pipe 12a, and information about the duct diameter D is stored in the storage unit 26b in advance.

The two-dimensional correction coefficient map has the same vertical axis and horizontal axis as the two-dimensional map of the eighth embodiment, and is individually provided for each of the duct diameters D1 to Dn. For example, in the two-dimensional map for the duct diameter D1, A111, B111 to A1nn, and B1nn are arranged as the slope Annnn and the intercept Bnnn corresponding to the average flow rate G and the pulsation frequency F. Further, in the two-dimensional map for the duct diameter Dn, An11, Bn11 to Annn, and Bnnn are arranged as the slope Annnn and the intercept Bnnn.

(11th Embodiment)
In the eighth embodiment, the correction amount acquisition unit 44 uses one error prediction formula for calculating the pulsation error Err, but in the eleventh embodiment, the correction amount acquisition unit 44 uses two error prediction formulas. .. In this embodiment, the differences from the eighth embodiment will be mainly described.

As shown by the broken line in FIG. 19, the pulsation characteristic of the present embodiment has a region where the pulsation error Err becomes smaller as the pulsation amplitude A is larger, and a region where the pulsation error Err becomes larger as the pulsation amplitude A is larger. Therefore, the threshold value As of the pulsation amplitude A is set for the boundary portion of these regions. Therefore, the correction amount acquisition unit 44 determines the correction coefficient map and the error depending on whether the pulsation amplitude A is smaller than the threshold value As (hereinafter, also referred to as A <As) or larger (hereinafter, also referred to as A> As). Use each prediction formula properly. When it is necessary to set the threshold value As, there is a case where a backflow of air flow rate occurs in the intake passage 12.

As shown in FIG. 20, as the two-dimensional correction coefficient map, there are a first map used when A <As and a second map used when A> As. In the first map, the relationship between the average flow rate G, the pulsation frequency F, the slope Ann, and the intercept Bnn is shown. On the other hand, in the second map, the slope Cnn and the intercept Dnn are included instead of the slope Ann and the intercept Bnn in the first map, and the relationship between the average flow rate G, the pulsation frequency F, the slope Cnn, and the intercept Dnn is It is shown. In the second map, C11, D11 to Cnn, and Dnn are arranged as the slope Cnn and the intercept Dnn.

When calculating the pulsation error Err, the correction amount acquisition unit 44 uses the above-mentioned (Equation 1) when A <As, and uses the following (Equation 3) as the error prediction formula when A> As.
Err = Cnn × A + Dnn ... (Equation 3)

When A <As, the correction amount acquisition unit 44 calculates the pulsation error Err as in the eighth embodiment by using the first map and the above-mentioned (Equation 1). On the other hand, in the case of A> As, the slope Cnn and the intercept Dnn corresponding to the average flow rate G and the pulsation frequency F are calculated by using the second map, and the slope Cnn and the intercept are calculated by using the above (Equation 3). The pulsation error Err according to Dnn is calculated.

According to the present embodiment, when measuring the pulsation error Err, the correction coefficient map and the error prediction formula can be used properly according to the presence or absence of backflow in the intake passage 12. Therefore, the measurement accuracy of the pulsation error Err can be improved as compared with the configuration in which the same correction coefficient map and the error prediction formula are used for the measurement of the pulsation error Err regardless of the presence or absence of backflow.

(12th Embodiment)
In the eleventh embodiment, the correction coefficient map is used properly according to the magnitude of the pulsation amplitude A, but in the twelfth embodiment, the correction coefficient map is used properly according to the magnitude of the pulsation rate P. In this embodiment, the differences from the eleventh embodiment will be mainly described.

The pulsation characteristic shown in FIG. 21 is different from the eleventh embodiment, and the horizontal axis is not the pulsation amplitude A but the pulsation rate P. The pulsation rate P is a value obtained by dividing the pulsation amplitude A by the average flow rate G. This relationship can also be shown by P = A / G × 100 [%]. Further, the pulsation characteristic has a region in which the pulsation error Err becomes smaller as the pulsation rate P is larger, and a region in which the pulsation error Err becomes larger as the pulsation rate P is larger. The threshold value Ps of the rate P is set. Therefore, the correction amount acquisition unit 44 determines the correction coefficient map and the error depending on whether the pulsation rate P is smaller than the threshold value Ps (hereinafter, also referred to as P <Ps) or large (hereinafter, also referred to as P> Ps). Use each prediction formula properly. The case where the threshold value Ps needs to be set includes the case where the backflow of the air flow rate occurs in the intake passage 12.

As shown in FIG. 22, as the two-dimensional correction coefficient map, there are a third map used when P <Ps and a fourth map used when P> Ps. In the third map, the relationship between the average flow rate G, the pulsation frequency F, the slope Ann, and the intercept Bnn is shown as in the first map of the eleventh embodiment. In the fourth map, the relationship between the average flow rate G, the pulsation frequency F, the slope Cnn, and the intercept Dnn is shown as in the second map of the eleventh embodiment.

When calculating the pulsation error Err, the correction amount acquisition unit 44 uses the following (Equation 4) as the error prediction formula when P <Ps, and the following (Equation 5) as the error prediction formula when P> Ps. ) Is used.
Err = Ann × P + Bnn ... (Equation 4)
Err = Cnn × P + Dnn ... (Equation 5)

The slopes Ann and Cnn are values that depend on the pulsation rate P, and are values that are changed for each of the average flow rate G and the pulsation frequency F as shown in the correction coefficient map.

According to the present embodiment, as in the eleventh embodiment, the measurement accuracy of the pulsation error Err can be improved by properly using the correction coefficient map and the error prediction formula according to the presence or absence of backflow in the intake passage 12. can.

According to the present embodiment, the pulsation rate P is used instead of the pulsation amplitude A for the correction coefficient map and the error prediction formula. Therefore, for the pulsation rate P, the threshold value Ps may be set to 100 [%] regardless of the average flow rate G when using the correction coefficient map or the error prediction formula properly according to the presence or absence of backflow in the intake passage 12. can. In this case, when the correction coefficient map and the error prediction formula are used properly, it is not necessary to change the threshold value Ps according to the average flow rate G, so that the calculation for calculating the pulsation error Err can be simplified. That is, the processing load when calculating the pulsation error Err can be reduced. On the other hand, in a configuration in which the pulsation amplitude A is used for the correction coefficient map and the error prediction formula, for example, as in the eleventh embodiment, it is considered necessary to change the threshold value As according to the average flow rate G. ..

(Other embodiments)
Although the plurality of embodiments according to the present disclosure have been described above, the present disclosure is not construed as being limited to the above embodiments, and is applied to various embodiments and combinations within the scope of the gist of the present disclosure. can do.

As a modification 1, the frequency characteristic may include a pulsating amplitude rate as a detection amplitude rate instead of the detection amplitude Am. The pulsation amplitude rate is a value obtained by dividing the difference between the detected peak value Ap and the detected average value Aa by the detected average value Aa. This pulsating amplitude ratio can also be expressed as (Ap-Aa) / Aa × 100. Even in a configuration in which the pulsation amplitude factor is used for estimating the pulsation frequency F, the same effect as in the configuration in which the detection amplitude Am is used for estimating the pulsation frequency F can be obtained as in each of the above embodiments. In addition to the detected amplitude Am, the pulsation amplitude rate also corresponds to the amplitude-related value.

As a modification 2, the relational value C was calculated using the detection peak value Ap and the attenuation peak value Bp as the detection-related value and the attenuation-related value. However, these peak values Ap and Bp are used to calculate the relational value C. Different detection-related and attenuation-related values may be used. For example, the peak values Ap and Bp are increased or decreased by a predetermined value or a predetermined rate, and the values are used as the detection-related value and the attenuation-related value.

Further, the detection value Sa and the attenuation value Sb at a predetermined timing may be used as the detection-related value and the attenuation-related value. For example, the detected peak value Ap is defined as a detection-related value, and the attenuation value Sb at the detection timing when the detected peak value Ap is detected is defined as an attenuation-related value. Even in this case, the relational value indicating the relation between the detection-related value and the attenuation-related value can be obtained.

Further, the relation value C may be calculated by using the detection bottom value Au and the attenuation bottom value Bu as the detection-related value and the attenuation-related value. For example, if the detected bottom value Au is larger than zero, the ratio of the attenuation bottom value Bu and the detected bottom value Au can be calculated as the relation value C. Further, for the bottom values Au and Bu, similarly to the peak values Ap and Bp, the relational values are calculated by using the values obtained by increasing or decreasing the bottom values Au and Bu by a predetermined value or a predetermined rate as the detection-related values and the attenuation-related values. May be good.

As a modification 3, instead of setting the ratio of the attenuation peak value Bp to the detected peak value Ap (for example, Bp / Ap) as the relational value C , the ratio of the detected peak value Ap to the attenuation peak value Bp (for example, Ap / Bp) is used. It may be a relational value .

As a modification 4, the relational value C may be a difference between the detected peak value Ap and the attenuation peak value Bp, not the ratio between the detected peak value Ap and the attenuation peak value Bp. For example, the value obtained by subtracting the attenuation peak value Bp from the detected peak value Ap is defined as the relation value C. In this configuration, even if the detection-related value such as the detection peak value Ap or the attenuation-related value such as the attenuation peak value Bp is zero, the relation value C can be calculated. Therefore, the pulsation frequency is used by using the relation value C. It is possible to suppress a decrease in estimation accuracy when estimating F. For example, in the configuration in which the ratio of the detection-related value and the attenuation-related value is the relational value as in the first embodiment, the relational value is properly calculated when the detection-related value or the attenuation-related value is zero. There is concern that it cannot be done.

As a modification 5, in the frequency characteristic showing the relationship between the relational value C, the pulsation frequency F, and the detected amplitude Aam, a value different from the detected amplitude Aam may be included as the amplitude-related value instead of the detected amplitude Aam. The amplitude -related values include a value obtained by increasing or decreasing the detected amplitude Am by a predetermined value or a predetermined rate, a difference between the detected peak value Ap and the detected bottom value Au, a difference between the detected average value Aa and the detected bottom value Au, and the like. Can be mentioned.

As a modification 6, in each of the above embodiments, the filter unit 36 that attenuates the detected value Sa is realized as one of the functions of the processing unit 26, but the filter unit 36 is realized as a structure by an electric circuit or the like. You may.

As a modification 7, the filter unit 36 may perform attenuation processing on the detection signal from the sensing unit 25 instead of the detection value Sa. In this case, the relational value indicating the relationship between the detection signal and the attenuated signal obtained by attenuated the detection signal is used for estimating the pulsation frequency F.

As a modification 8, in each of the above embodiments, the pulsation frequency F is estimated using both the relational value C and the detected amplitude Aam, but the pulsating frequency F is estimated based on the relational value C without using the detected amplitude Aam. You may. For example, a mathematical formula or a coefficient for the relational value C is set so that the pulsation frequency F can be directly estimated from the relational value C.

As a modification 9, in the fifth embodiment, the current specific period Ts is set from the pulsation frequency F acquired in the previous process of the frequency acquisition unit 43, but the current specific period Ts is further than the previous time. The pulsation frequency F acquired by the frequency acquisition unit 43 in the past processing may be set. Further, the specific period Ts may be set to a value different from the reciprocal of the pulsation frequency F. For example, a value obtained by increasing or decreasing a predetermined value or a predetermined rate from the reciprocal of the pulsation frequency F is set as the specific period Ts.

As a modification 10, in each of the above embodiments, the pulsation estimation unit 30 is included in the processing unit 26 of the air flow meter 15, but the pulsation estimation unit 30 may be included in the ECU 20. In this case, the ECU 20 corresponds to the air flow rate measuring device. Further, a part of the functions of the pulsation estimation unit 30 may be included in the processing unit 26, and the remaining functions may be included in the ECU 20. In this case, the processing unit 26 and the ECU 20 cooperate as a plurality of arithmetic units to exert a function as an air flow rate measuring device. Further, various programs may be stored in a non-transitional substantive storage medium such as a flash memory or a hard disk provided in each arithmetic unit.

As a modification 11, the ECU 20 and the processing unit 26 may be configured to include a dedicated electric circuit unit having at least one integrated circuit or a passive element. For example, in a configuration in which the processing unit 26 has a plurality of dedicated electric circuit units, a plurality of functions such as a signal acquisition unit 31 possessed by the pulsation estimation unit 30 in the processing unit 26 are performed by at least one dedicated electric circuit unit. It is configured.

25 ... Sensing unit, 26 ... Processing unit as an air flow rate measuring device, 32 ... Period setting unit, 35 ... Detection peak acquisition unit as a detection acquisition unit, 36 ... Filter unit as a filter, 37 ... Attenuation as an attenuation acquisition unit Peak acquisition unit, 38 ... relationship acquisition unit , 42 ... amplitude acquisition unit, 43 ... frequency acquisition unit, 44 ... correction amount acquisition unit constituting the detection correction unit, 49 ... flow rate correction unit as detection correction unit, Aa ... detection average Value, Am ... Detection amplitude as amplitude-related value, Ap ... Detection-related value and detection peak value as maximum value, Au ... Detection bottom value as minimum value, Bp ... Attenuation-related value and attenuation peak value as maximum value, Bu ... Attenuation bottom value as the minimum value, C ... Relation value , F ... Pulsation frequency, Q ... Correction amount as the correction value, Sa ... Detection value, Sb ... Attenuation value, Ts ... Specific period.

Claims (6)

An air flow rate measuring device (26) that measures an air flow rate based on a detection value (Sa) detected by a sensing unit (25) according to an air flow.
A detection acquisition unit (35) that acquires the maximum value (Ap) or the minimum value (Au) of the detection value as a detection-related value for a predetermined specific period (Ts).
Attenuation acquisition unit that acquires the maximum value (Bp) or the minimum value (Bu) of the attenuation value in the specific period as the attenuation-related value for the attenuation value (Sb) obtained by attenuated the detected value by a predetermined filter (36). (37) and
As the relational value (C) indicating the relationship between the detection-related value and the attenuation-related value, the ratio of the detection-related value to the attenuation-related value or the difference between the detection-related value and the attenuation-related value is acquired. Relationship acquisition department (38) and
A frequency acquisition unit (43) for acquiring the pulsation frequency (F) of the air using the relational value, and a frequency acquisition unit (43).
A correction amount acquisition unit (44) that acquires a correction amount (Q) using the pulsation frequency, and
For the specific period, the difference between the maximum value of the detected value and the average value (Aa) of the detected value, the difference between the average value and the minimum value of the detected value, and the maximum value of the detected value and the detected value. An amplitude acquisition unit (42) that acquires an amplitude factor obtained by dividing the difference from the minimum value or the difference between the maximum value and the average value of the detected values by the average value as an amplitude-related value.
Equipped with
The frequency acquisition unit estimates the pulsating frequency from the relational value and the amplitude-related value by using the frequency characteristic that specifies the relationship between the relational value, the amplitude-related value, and the pulsating frequency.
An air flow rate measuring device that calculates the air flow rate by correcting the detected value using the correction amount. The frequency acquisition unit
The pulsation frequency is determined in advance for the filter that attenuates the detected value, and is based on the relational value and the amplitude-related value, using a frequency characteristic indicating the relationship between the relational value, the amplitude-related value, and the pulsating frequency. The air flow rate measuring device according to claim 1 . The frequency characteristic indicates that when the amplitude-related value is a predetermined value, the pulsating frequency is so small that the difference between the detection-related value and the attenuation-related value is small. Item 2. The air flow rate measuring device according to item 2. The detection acquisition unit acquires the maximum value of the detection value as the detection peak value (Ap) for the specific period as the detection-related value.
The attenuation acquisition unit acquires the maximum value of the attenuation value as the attenuation peak value (Bp) for the specific period as the attenuation-related value.
The relationship acquisition unit acquires, as the relationship value, the ratio between the detected peak value and the attenuation peak value, or the difference between the detected peak value and the attenuation peak value, any one of claims 1 to 3 . The air flow rate measuring device according to one. 1 The air flow rate measuring device according to any one of 4 to 4 . It is an air flow rate measuring method that measures an air flow rate based on a detection value (Sa) detected by a sensing unit (25) according to an air flow.
For a predetermined specific period (Ts), the maximum value (Ap) or the minimum value (Au) of the detected value is acquired as a detection-related value (35).
With respect to the attenuation value (Sb) obtained by attenuated the detected value by a predetermined filter (36), the maximum value (Bp) or the minimum value (Bu) of the attenuation value in the specific period is acquired as an attenuation-related value (37). ,
As the relational value (C) indicating the relationship between the detection-related value and the attenuation-related value, the ratio of the detection-related value to the attenuation-related value or the difference between the detection-related value and the attenuation-related value is acquired. (38),
The pulsation frequency (F) of the air is obtained using the relational value (43).
The correction amount (Q) is obtained using the pulsation frequency (44),
For the specific period, the difference between the maximum value of the detected value and the average value (Aa) of the detected value, the difference between the average value and the minimum value of the detected value, and the maximum value of the detected value and the detected value. The amplitude factor obtained by dividing the difference from the minimum value or the difference between the maximum value and the average value (Aa) of the detected value by the average value is obtained as an amplitude-related value (42).
Using the frequency characteristics that specify the relationship between the relational value, the amplitude-related value, and the pulsating frequency, the pulsating frequency is estimated from the relational value and the amplitude-related value.
An air flow rate measuring method for calculating the air flow rate by correcting the detected value using the correction amount.

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