JP6464709B2 - Air flow meter - Google Patents

Description

  The present invention relates to an air flow meter equipped with an intake air temperature sensor that detects the temperature of intake air sucked into an engine (internal combustion engine).

(Conventional technology)
Although an air flow meter equipped with an intake air temperature sensor is known, the intake duct to which the air flow meter is attached becomes hot due to the heat of the engine, and the passage forming member (the member forming the internal passage) rises in temperature due to heat transfer. However, there is a concern that the intake air temperature sensor may not be able to accurately measure the intake air temperature due to the heat effect of the passage forming member.
Similarly, the sensor circuit mounted inside the air flow meter self-heats, and the temperature of the passage forming member rises under the influence of the sensor circuit, and the intake air temperature sensor receives the thermal effect of this passage forming member to accurately determine the intake air temperature. There is also concern that it will be impossible to measure.

  Therefore, temperature measurement is performed separately from the intake temperature sensor at a location (for example, an installation location of the intake temperature sensor or a sensor circuit disposed inside the intake passage member) that is affected by heat transmitted to the passage formation member. A technique has been proposed in which a second temperature sensor is provided and the effect of heat transfer on the intake air temperature sensor is suppressed by correction based on a second temperature signal measured by the second temperature sensor (see, for example, Patent Document 1). .

(Problems of conventional technology)
In each case (intake air when the intake duct receives heat from the engine during cold start, etc.), when the heat generation state of the sensor circuit changes, or when the intake air temperature reaching the air flow meter changes, etc. It takes several tens of seconds to several minutes for the temperature of the temperature sensor, the second temperature sensor, the passage forming member, and the like to stabilize, and during this time, it becomes difficult to perform the temperature correction. As a result, the intake air temperature cannot be accurately corrected due to the heat transfer delay until the temperatures of the measurement portions of the intake air temperature sensor and the second temperature sensor are stabilized (temperature change period: transient period).

For the purpose of assisting understanding, a case where “the intake air temperature reaching the air flow meter has changed” will be described as an example.
When the intake air temperature changes (see the solid line A in FIG. 6), the detected temperature of the intake air temperature sensor has a response delay due to the heat capacity (see the solid line B in FIG. 6), and the detected temperature of the second temperature sensor also responds due to the difference in heat capacity. A delay occurs (see solid line C in FIG. 6).

Patent Document 1 discloses a technique for compensating the response of the output of the intake air temperature sensor (intake air temperature signal) in accordance with the output of the flow sensor (flow signal) (see claim 9 and FIG. 6 of Patent Document 1). ).
The technique disclosed in Patent Document 1 directly compensates the response of the output of the intake air temperature sensor.

However, when a temperature change is received, a time difference (response delay) occurs due to the difference in heat capacity and heat transfer between the stabilization of the output of the intake temperature sensor and the stabilization of the output of the second temperature sensor. Therefore, it takes time for the output difference (deviation) between the intake air temperature sensor and the second temperature sensor to stabilize.
Specifically, when the temperature of the intake air reaching the air flow meter changes, it takes time until the temperature of the passage forming member is stabilized. For this reason, it takes a long time for the output of the second temperature sensor provided in the passage forming member to stabilize, and the response delay of the second temperature sensor becomes larger than the response delay of the intake air temperature sensor. .

  Since the technology disclosed in Patent Document 1 compensates the response of the output of the intake air temperature sensor, there is a response delay due to a difference in heat capacity and heat transfer of the second temperature sensor with respect to the intake air temperature sensor, and a response delay of the sensor itself Not compensated. For this reason, even if the technique disclosed in Patent Document 1 is used, there is a problem that high correction accuracy cannot be obtained in the temperature change period.

  Specifically, when the technique disclosed in Patent Document 1 is employed to correct the intake air temperature signal, there is a response delay with respect to the actual intake air temperature (solid line A) as shown by the solid line J in FIG. At the same time, there is a problem that overshoot due to overcorrection occurs, and a problem that high correction accuracy cannot be obtained during the temperature change period.

JP 2012-159314 A

  The present invention has been made in view of the above problems, and an object thereof is to provide an air flow meter capable of improving the detection accuracy of the intake air temperature in the temperature change period (transition period).

Unlike the prior art described above, the present invention compensates for the response delay of the second temperature sensor (32) and corrects the intake air temperature, so that the detection accuracy of the intake air temperature can be improved compared to the prior art.
Specifically, the response of the output difference (tc) between the “intake air temperature signal (ta) measured by the intake air temperature sensor (31)” and the “second temperature signal (tb) measured by the second temperature sensor (32)”. By correcting the intake air temperature using the output difference (tc) compensated for the delay and compensated for the response, the detection accuracy of the intake air temperature during the temperature change period can be improved.

(A) Schematic diagram of air flow meter viewed from intake upstream side, (b) Schematic sectional view of air flow meter cut along intake flow (Example 1). It is a schematic block diagram of the electric circuit mounted in an air flow meter (Example 1). (Example 1) which is the schematic of a sensor board | substrate. It is a schematic block diagram of the correction | amendment means which correct | amends an intake air temperature signal. (A) Frequency characteristic diagram of response compensation, (b) Characteristic diagram of time constant with respect to flow rate. It is explanatory drawing of each temperature change in a temperature change period. (A) Schematic of air flow meter viewed from intake upstream side, (b) Schematic cross-sectional view of air flow meter cut along intake flow (Example 2). (Example 2) which is the schematic of a sensor board | substrate. (A) The schematic of the air flow meter seen from the intake upstream side, (b) It is the schematic sectional drawing of the air flow meter cut along the intake flow (Example 3). (A) The schematic of the air flow meter seen from the intake upstream side, (b) It is the schematic sectional drawing of the air flow meter cut along the intake flow (Example 4).

  Hereinafter, “DETAILED DESCRIPTION OF THE INVENTION” will be described in detail.

  A specific example (example) of the present invention will be described with reference to the drawings. The following “Example” discloses a specific example, and it goes without saying that the present invention is not limited to the “Example”.

[Example 1]
A first embodiment will be described with reference to FIGS.
The air flow meter is mounted on an intake duct 1 (air cleaner outlet, intake pipe, etc.) that guides intake air (combustion air) to a vehicle running engine, and at least an intake air flow (air flow) sucked into the engine. Measure.

Air flow meter
A passage forming member 3 provided with a lid 2;
A flow sensor 4 assembled inside the passage forming member 3;
It is configured with.

  An airflow meter mounting hole penetrating the inside and outside is formed on the side surface of the air intake duct 1. After the passage forming member 3 is inserted into the air intake duct 1 from the outside of the airflow meter mounting hole, the air flow is blocked by the lid portion 2. The air flow meter is assembled to the intake duct 1 by closing the meter mounting hole and fixing the lid 2 to the intake duct 1 using fixing means such as a tapping screw.

  The passage forming member 3 is formed of, for example, a resin material (not limited), and a bypass through which a part of the intake air flowing through the inside of the intake duct 1 (main air passage) passes inside the passage forming member 3. A passage 5 (sub air passage) and a sub bypass passage 6 (sub air passage) are formed.

  The bypass passage 5 is an air passage through which a part of the air flowing in the intake duct 1 passes, and the passage is formed along the intake air flow direction in the intake duct 1. An air intake 5 a is provided on the intake upstream side of the bypass passage 5, and an air discharge port 5 b is provided on the intake downstream side of the bypass passage 5. Note that an outlet restrictor for restricting the air flow passing through the bypass passage 5 is formed in the air discharge port 5b.

The sub-bypass passage 6 returns the air flow passing through the sub-bypass passage 6 into the intake duct 1 and the inlet 6a into which a part of the air flow of the bypass passage 5 throttled by the outlet throttle (air discharge port 5b) flows. The detour is formed so as to return the air flowing in from the inlet 6a inside the passage forming member 3 and returning it into the intake duct 1.
FIG. 1 discloses an example in which an outlet (not shown) of the sub-bypass passage 6 is provided independently. However, the present invention is not limited thereto. For example, the sub-bypass passage 6 is opened by opening the outlet in the bypass passage 5. The air flow that has passed may be returned to the bypass passage 5 again.

  The lid 2 provided integrally with the passage forming member 3 includes a connector for connecting an ECU (engine control unit), and the lid 2 and the passage forming member 3 are provided by a common resin material.

The flow sensor 4 is assembled and disposed inside the passage forming member 3.
A sensor substrate 8 provided with a flow rate detection unit 7 for measuring the intake flow rate;
A sensor circuit 9 electrically connected via a connector formed on the passage forming member 3;
A circuit housing 10 that houses the sensor circuit 9;
It is configured with.

Specifically, the flow sensor 4 is a thermal type that measures the intake air amount based on the heat amount,
A heater control bridge 11 that heats part of the intake air;
A flow rate detection bridge 12 for obtaining a flow rate signal corresponding to the flow rate from the heated intake air,
A digital circuit 13 for calculating a flow rate from a flow rate signal;
It is configured with.

An example of the heater control bridge 11 is
Three resistors provided on the sensor substrate 8,
Two amplifying means provided in the sensor circuit 9,
Consists of.

The three resistors in the heater control bridge 11 are:
A heating heater 14 for heating a part of the air passing through the sub-bypass passage 6 by heat generated by energization;
An indirectly heated resistor 15 disposed in the vicinity of the heater 14 and generating a voltage value V1 corresponding to the temperature of the air heated by the heater 14 (heated intake air temperature);
An intake air temperature resistor 16 that measures the temperature of the intake air that is not heated by the heater 14 (non-heated intake air temperature);
A voltage dividing resistor 17 connected in series to the intake air temperature resistor 16 to generate a voltage value V2 corresponding to the unheated intake air temperature;
Consists of.

  The two amplifying means in the heater control bridge 11 are an operational amplifier 18 that generates an output corresponding to the voltage difference between the voltage value V1 and the voltage value V2, and a transistor 19 that applies a current corresponding to the output of the operational amplifier 18 to the heater 14. The heater 14 is kept at the reference temperature by energizing the heater 14 so that the voltage difference between the voltage value V1 and the voltage value V2 becomes a preset voltage difference.

An example of the flow detection bridge 12 is
Four resistors provided on the sensor substrate 8;
One amplifying means provided in the sensor circuit 9,
Consists of.

The four resistors in the flow detection bridge 12 are:
First and second upstream resistors 21 and 22 provided on the upstream side of the heat generating portion (the heat generating heater 14 and the indirectly heated resistor 15);
First and second downstream resistors 23 and 24 provided on the downstream side of the heat generating part,
Consists of.
The first upstream resistor 21 and the first downstream resistor 23 are connected in series to generate a voltage value V3 corresponding to the intake air amount. The second upstream resistor 22 and the second downstream resistor 24 are also A voltage value V4 corresponding to the intake air amount is generated by being connected in series.

When air flows through the sub-bypass passage 6, the detected temperatures of the first and second upstream resistors 21 and 22 and the detection of the first and second downstream resistors 23 and 24 according to the intake flow rate and the flow direction of the intake air. Since there is a temperature difference with the temperature, the intake air amount and the flow direction of the intake air can be measured based on the temperature difference.
Specifically, when a temperature difference occurs between the detected temperature of the first and second upstream resistors 21 and 22 and the detected temperature of the first and second downstream resistors 23 and 24, the first and second upstream resistors When the resistance values of the bodies 21 and 22 and the resistance values of the first and second downstream resistance bodies 23 and 24 change, the voltage values V3 and V4 change.

  One amplifying means in the flow rate detection bridge 12 is an operational amplifier 25 that generates an output corresponding to the potential difference between the voltage values V3 and V4.

  The digital circuit 13 corrects the flow rate signal output from the flow rate detection bridge 12 based on the correction value stored in the memory, frequency-modulates the corrected flow rate signal vf, and outputs it to an external ECU (in an example). Yes, without limitation).

(Description of intake air temperature sensor 31)
The air flow meter of this embodiment includes an intake air temperature sensor 31 that measures the temperature of intake air passing through the intake duct 1 (the temperature of intake air sucked into the engine).
As shown in FIG. 1A, the intake air temperature sensor 31 of this embodiment is disposed outside the passage forming member 3 and measures the temperature of intake air flowing inside the intake duct 1. Specifically, the intake air temperature sensor 31 is disposed in a hollow space that is a predetermined amount away from the passage formation member 3 so as to suppress the heat transfer effect of the passage formation member 3 as much as possible.

As a specific example, the intake air temperature sensor 31 of this embodiment is a thermistor element having a bobbin-type resistor shape, a thermistor body whose resistance value changes depending on temperature, and two lead wires extending from the thermistor body. With. The two lead wires are supported by the lid portion 2 or the passage forming member 3, so that the thermistor body is supported in a hollow distance from the passage forming member 3 by a predetermined amount.
The intake air temperature signal ta (signal corresponding to the intake air temperature) measured by the intake air temperature sensor 31 is corrected by an intake air temperature correction means 50 described later, and then frequency-modulated by the digital circuit 13 in the same manner as the flow rate signal vf. To the ECU (not limited).

(Description of the second temperature sensor 32)
The air flow meter of this embodiment includes a second temperature sensor 32 that measures the temperature at a location that is affected by heat transmitted to the passage forming member 3. That is, the thermal effect received by the second temperature sensor 32 from the passage forming member 3 is larger than the thermal effect received by the intake temperature sensor 31 from the passage forming member 3.
The second temperature sensor 32 is provided independently of the intake air temperature sensor 31 described above.

Although the mounting location of the 2nd temperature sensor 32 is not limited, it is provided in the flow sensor 4 as a specific example.
Furthermore, the mounting location of the second temperature sensor 32 in the flow rate sensor 4 is not limited. As an example, the second temperature sensor 32 is mounted on the sensor circuit 9 in this embodiment. Thus, by mounting the second temperature sensor 32 on the sensor circuit 9, the specification change for mounting the second temperature sensor 32 on the existing air flow meter (specification change of the passage forming member 3 and the circuit housing 10). The effect of simplifying the routing of the lead wiring of the second temperature sensor 32 can be obtained.

(Description of intake air temperature correction means 40).
In the airflow meter of this embodiment, the influence of heat transfer to the intake air temperature sensor 31 (from the passage forming member 3 to the intake air temperature sensor 31 based on the second temperature signal tb measured by the second temperature sensor 32). ) Is provided.

Here, “when the intake duct 1 receives the heat of the engine during cold start”, “when the heat generation state of the sensor circuit 9 changes”, or “the intake air temperature reaching the air flow meter in the intake duct 1 is When “changed” or the like, a response delay occurs in the outputs of the intake air temperature sensor 31 and the second temperature sensor 32, and a temperature change also occurs in the passage forming member 3.
For this reason, although the temperature of each part is stabilized, a response delay occurs for several tens of seconds to several minutes. When the temperature change is received in this way, it is difficult to accurately correct the intake air temperature during a period until the temperature of each part is stabilized (temperature change period) due to a response delay until the temperature becomes stable.

As means for solving this problem, the air flow meter of this embodiment includes means for compensating for a response delay in the temperature change period.
Specifically, in the air flow meter of this embodiment, as means for compensating for the response delay, “the intake air temperature signal ta measured by the intake air temperature sensor 31 and the second temperature based on the“ flow signal vf measured by the flow sensor 4 ””. Response compensation means 41 for compensating for a response delay of the output difference tc of the second temperature signal tb measured by the sensor 32 is provided. The intake air temperature signal ta measured by the intake air temperature sensor 31 is corrected based on the output difference tc compensated by the response compensation means 41.

A specific configuration of the intake air temperature correction means 40 will be described with reference to FIG.
The intake air temperature correcting means 40 is provided in the digital circuit 13 (not limited).
In addition to the response compensation means 41 described above, the digital circuit 13 includes
An output difference calculating means 42 for obtaining an output difference tc between “the intake temperature signal ta measured by the intake temperature sensor 31” and “the second temperature signal tb measured by the second temperature sensor 32”;
A flow rate calculation means 43 for calculating the intake flow rate from the output signal of the flow rate detector 7 (the output signal of the operational amplifier 25);
Correction execution means 44 for correcting the intake air temperature signal ta measured by the intake air temperature sensor 31 using the output difference tc (compensated signal) compensated by the response compensation means 41;
Is provided.

  The output difference calculating means 42 is a subtracting means for obtaining the output difference tc by subtracting the “second temperature signal tb measured by the second temperature sensor 32” from the “intake temperature signal ta measured by the intake temperature sensor 31”. .

The flow rate calculation means 43 is
A frequency calculation unit 43a that obtains a flow rate frequency that is a frequency of a flow rate change caused by intake pulsation;
An amplitude calculation unit 43b for obtaining a flow rate amplitude that is a flow rate change width caused by intake pulsation;
An average flow rate calculation unit 43c that obtains an average flow rate obtained by averaging the measured flow rate per unit time;
- above determined flow rate frequency, flow amplitude, a characteristic converting unit 43d to obtain the flat Hitoshiryu amount or et flow signal vf,
It is configured with.

As described above, the flow rate calculation means 43 employed in this embodiment obtains the flow rate signal vf using the “flow rate frequency”, “flow rate amplitude” , and “ average flow rate ”, thereby obtaining the absolute value of the intake flow rate (with time passage). A stable flow rate signal vf can be obtained as compared with the conventional technique for obtaining a variable value).
The flow rate calculation means 43 may be a means for obtaining a flow rate signal vf output from the air flow meter, or may be provided exclusively for performing response compensation.

The response compensation means 41 is “phase advance compensation” that advances the response delay caused by the characteristic disturbance during the temperature change period by compensation (which is an example and not limited), and the response delay of the output difference tc obtained by the subtraction means is the phase. Compensation is made by lead compensation.
Although the specific configuration of the response compensation means 41 (phase advance compensation) is not limited, an example will be described for the purpose of assisting understanding.

The response compensation means 41 of this embodiment is
Gain calculating means for calculating the gain used for compensation according to the frequency (frequency obtained by Fourier transforming the intake air temperature change with respect to the time axis);
Time constant calculating means for calculating a time (time constant) for executing response compensation using the calculated gain based on the intake flow rate;
Multiplication means for correcting the output difference tc based on the obtained gain and time constant;
Is provided.

  As described above, the gain calculation means calculates the gain according to the frequency. As shown in FIG. 5A, a specific example is that the gain is reduced when the frequency is low, and the frequency is high. Sometimes it increases the gain. The gain according to the frequency may be given by a map or may be given by an arithmetic expression.

  The time constant calculating means prevents the response of the output difference tc from deteriorating as the intake air flow rate becomes lower. A specific example is as shown in FIG. The time constant is set longer and the time constant is set shorter as the intake flow rate increases. The time constant corresponding to the intake flow rate may be given by a map or may be given by an arithmetic expression.

The correction execution unit 44 is an addition unit that adds the “output difference tc compensated by the response compensation unit 41” to the “intake temperature signal ta measured by the intake temperature sensor 31” and outputs the corrected intake air temperature signal ta. .
The corrected intake air temperature signal ta is output to the ECU after frequency modulation (not limited) as described above.

(Effect 1 of Example 1)
As described above, the air flow meter according to the first embodiment is based on “the flow rate signal vf measured by the flow rate sensor 4” and “the second temperature sensor 32 measured by the intake temperature signal ta measured by the intake temperature sensor 31”. The response delay of the output difference tc of the temperature signal tb is compensated. That is, even when a response delay occurs in the output difference tc, such as when the intake air temperature changes, the response compensation means 41 compensates for the response delay in the output difference tc.
As a result, since the intake air temperature can be corrected including a response delay of the second temperature sensor 32, the detection accuracy of the intake air temperature in the temperature change period (transition period) can be improved as compared with the prior art.

An example of a specific effect will be described with reference to FIG.
When the intake air temperature changes (see the solid line A in FIG. 6), the detected temperature of the intake air temperature sensor 31 has a response delay due to the heat capacity (see the solid line B in FIG. 6), and the detected temperature of the second temperature sensor 32 also responds by the heat capacity. A delay occurs (see solid line C in FIG. 6).
In this way, when the temperature of the intake air reaching the air flow meter changes, it takes a long time for the output of the second temperature sensor 32 provided in the passage forming member 3 to stabilize. However, the response delay of the second temperature sensor 32 becomes large. That is, a response delay occurs in the second temperature signal tb with respect to the intake air temperature signal ta, and a response delay occurs in the output difference tc.

Therefore, in this embodiment, response compensation is performed for the “output difference tc between the intake air temperature signal ta and the second temperature signal tb”, so that the intake air temperature signal ta is corrected including the response delay of the second temperature sensor 32. Therefore, the corrected intake air temperature signal ta can be very approximated to the actual intake air temperature (solid line A) as shown by the solid line D in FIG.
That is, by adopting the present invention, it is possible to improve the responsiveness of the correction according to the output difference tc, and it is possible to improve the detection accuracy of the intake air temperature even in the temperature change period.

(Effect 2 of Example 1)
Unlike this embodiment, when an intake air flow obtained directly from a signal detected from the flow rate detector is used as the intake air flow used for response compensation (that is, when the absolute value of the intake air flow is used for response compensation), The intake flow rate used for response compensation is not stable, and as a result, response compensation is difficult to stabilize.
In contrast, the air flow meter of the first embodiment, as described above, the flow rate frequency, flow amplitude, flat Hitoshiryu amount or al obtained a stable intake air flow rate (specifically, stable flow rate signal vf) using Response compensation. Thereby, stable response compensation can be performed, and the measurement accuracy of the intake air temperature after the response compensation (that is, the corrected intake air temperature ta) can be increased.

[Example 2]
A second embodiment will be described with reference to FIGS. In the following embodiments, the same reference numerals as those in the first embodiment denote the same functions.
In the first embodiment, the example in which the intake air temperature sensor 31 is provided outside the passage forming member 3 has been described.
On the other hand, as shown in FIG. 8, the intake air temperature sensor 31 according to the second embodiment is provided on the sensor substrate 8 and is disposed in the sub-bypass passage 6 together with the flow rate detection unit 7. The second temperature sensor 32 is provided in the flow rate sensor 4 as in the first embodiment.

As described above, even if the intake air temperature sensor 31 is arranged in the sub bypass passage 6 that is easily affected by the heat from the passage forming member 3, based on the second temperature signal tb measured by the second temperature sensor 32, By correcting the effect of heat transfer on the intake air temperature sensor 31, it is possible to measure the intake air temperature excluding the effect of heat transfer on the intake air temperature sensor 31.
Of course, by implementing the response compensation disclosed in the first embodiment, it is possible to improve the detection accuracy of the intake air temperature even in the temperature change period.

[Example 3]
A third embodiment will be described with reference to FIG.
In the first embodiment, the second temperature sensor 32 is provided in the flow rate sensor 4.
In contrast, the air flow meter of the third embodiment is equipped with a humidity sensor 51, and uses an environmental temperature sensor built in the humidity sensor 51 as the second temperature sensor 32. That is, in the third embodiment, an environmental temperature sensor built in the humidity sensor 51 in advance is used as the second temperature sensor 32.

  Specifically, the humidity sensor 51 is a well-known capacitance type. This type of humidity sensor 51 incorporates an environmental temperature sensor as means for correcting the detected humidity in accordance with the environmental temperature (the temperature at which the humidity sensor 51 is mounted). Therefore, in the third embodiment, an environmental temperature sensor mounted on the humidity sensor 51 is used as the second temperature sensor 32.

  As described above, in the air flow meter equipped with the humidity sensor 51, the environmental temperature sensor mounted on the humidity sensor 51 can be used as the second temperature sensor 32, so that it is not necessary to provide the dedicated second temperature sensor 32. For this reason, while being able to acquire the effect similar to the said Example 1, the implementation cost of this invention in the case of mounting the humidity sensor 51 in an air flow meter can be held down.

  In addition, this Example 3 shows the example which mounts the humidity sensor 51 on the inner wall of the sub bypass passage 6 of the downstream of the sensor board | substrate 8 as an example of the mounting location of the humidity sensor 51, as shown in FIG.

[Example 4]
A fourth embodiment will be described with reference to FIG.
The fourth embodiment shows a specific example in which the humidity sensor 51 is mounted in a portion different from the third embodiment, and the humidity sensor 51 is arranged on the inner wall of the sub bypass passage 6 on the upstream side of the sensor substrate 8. It is.
Even if it provides in this way, the same effect as Example 3 can be acquired.

  In the above embodiment, a chip type using the sensor substrate 8 is shown as an example of the flow rate detection unit 7, but the present invention is not limited to the chip type, and other types such as a bobbin type resistor are used. You may employ | adopt the flow volume detection part 7 of the structure of these.

  In the above embodiment, an air flow meter in which two air passages (bypass passage 5 and sub-bypass passage 6) are formed in the passage forming member 3 is shown. However, one air passage (in the passage forming member 3) The present invention may be applied to an air flow meter in which only an intake air amount measurement passage) is formed.

  In the above embodiment, an example in which the flow direction of the air to be measured passing through the flow rate detection unit 7 is opposite to the flow direction of the air flowing through the intake duct 1 is shown. The flow direction is not limited to the forward direction along the flow direction of the air flowing through the intake duct 1 or the direction perpendicular to the flow direction of the air flowing through the intake duct 1.

3 passage forming member 4 flow rate sensor 5 bypass passage (an example of a passage formed inside the passage forming member)
6 Sub-bypass passage (an example of a passage formed inside the passage forming member)
31 Intake air temperature sensor 32 Second temperature sensor 41 Response compensation means

Claims (5)

A passage forming member (3) for forming a passage (5, 6) through which a part of the intake air sucked into the engine passes, a flow rate sensor 4 (4) for measuring an intake air flow rate passing through the passage (6), and an intake air In an air flow meter comprising an intake air temperature sensor (31) for measuring temperature,
This air flow meter
A second temperature sensor (32) which is provided independently of the intake air temperature sensor (31) and performs temperature measurement at a location affected by heat transmitted to the passage forming member (3);
Based on the flow rate signal (vf) measured by the flow rate sensor (4), the intake temperature signal (ta) measured by the intake temperature sensor (31) and the second temperature signal measured by the second temperature sensor (32). Response compensation means (41) for compensating the response delay of the output difference (tc) of (tb),
An air flow meter for correcting an intake air temperature signal (ta) measured by the intake air temperature sensor (31) based on an output difference (tc) compensated by the response compensation means (41). The air flow meter according to claim 1,
The air flow meter, wherein the intake air temperature sensor (31) is disposed outside the passage forming member (3) . The air flow meter according to claim 1 ,
The flow sensor (4) includes a sensor substrate (8) provided with a flow rate detector (7) for measuring the intake flow rate.
The air flow meter is characterized in that the intake air temperature sensor (31) is provided on the sensor substrate (8) and is disposed in the passage (6) together with the flow rate detector (7) . In the air flow meter according to any one of claims 1 to 3 ,
The air flow meter, wherein the second temperature sensor (32) is provided in the flow rate sensor (4) . In the air flow meter according to any one of claims 1 to 3 ,
This air flow meter includes a humidity sensor (51) for measuring the humidity of intake air,
The second temperature sensor (32), air flow meter, characterized in Rukoto using an environmental temperature sensor which is built the humidity sensor (51).

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