JP2012247266A - Thermal flow rate measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal flowmeter which is capable of reducing a flow rate error caused by an attitude change of a flow rate sensor.SOLUTION: A thermal flowmeter comprises a flow rate sensor which is integrated in a sensor housing, and an inclination sensor 4 which detects an attitude change of the flow rate sensor. The flow rate sensor includes a flow rate correction section 37 which corrects a flow rate error caused by the attitude change. The flow rate correction section 37 has a correction map recording therein correlation data of the flow rate error caused by the attitude change of the flow rate sensor and an intake amount, the flow rate error is determined by the correction map on the basis of a detection result of the inclination sensor 4, and the intake amount detected by the flow rate sensor is corrected in accordance with the flow rate error. If the attitude change of the flow rate sensor is detected by the inclination sensor 4, the flow rate error is determined on the basis of the detection result of the inclination sensor 4, and the intake amount detected by the flow rate sensor is corrected just by the flow rate error, thereby reducing the flow rate error caused by the attitude change of the flow rate sensor.

Description

  The present invention relates to a thermal flow rate measuring device that detects a flow rate of a fluid flowing through a fluid passage using a flow rate sensor.

2. Description of the Related Art Conventionally, a thermal flow sensor that detects a flow rate of fluid such as air or gas is known.
This flow sensor has a heater element that is heated to a reference temperature that is higher than the fluid temperature by a certain temperature, and resistance temperature detectors that are respectively arranged on the upstream side and the downstream side of the heater element with respect to the fluid flow direction. In this method, the fluid flow rate is detected from the temperature difference between the upstream resistance temperature detector and the downstream resistance temperature detector.
By the way, when the flow sensor is used as an integrated flow meter such as a gas meter, the mounting posture of the flow sensor changes depending on the direction of the pipe to be laid and the flow direction of the fluid (gas) flowing through the pipe. For example, as shown by an arrow in FIG. 10A, when a fluid flows in the horizontal direction, as shown by an arrow in FIG. 10B, when a fluid flows from bottom to top, FIG. When the fluid flows from the top to the bottom as indicated by the arrows in FIG. 10A to 10C show a sensor chip 14 used for the flow sensor, and a heater element and a resistance temperature detector are arranged on a membrane 16 provided on the sensor chip 14. Yes.

However, as shown in FIGS. 10A to 10C, when the mounting posture of the sensor chip 14 is changed, the influence of heat caused by natural convection of the fluid heated by the heater element is different. An error occurs. That is, since the heat generated from the heater element is likely to diffuse upward due to the natural convection of the fluid, in the case of FIG. 10 (a) where the fluid flows in the horizontal direction, the movement of the heat due to the natural convection of the fluid does not occur. The effect on flow rate detection is reduced. In other words, since the influence on the temperature difference between the upstream resistance thermometer and the downstream resistance thermometer (the influence of heat caused by the natural convection of the fluid) is small, the flow rate error becomes small.
On the other hand, in the case of FIG. 10 (b), the movement of heat due to natural convection is added to the movement of heat accompanying the flow of the fluid. The temperature difference between the resistance temperature detector and the downstream resistance temperature detector increases.

On the other hand, in the case of FIG. 10 (c), the movement of heat due to natural convection acts so as to prevent the movement of heat accompanying the flow of the fluid. The temperature difference between the resistance temperature detector on the side and the resistance temperature detector on the downstream side is reduced.
As a result, as shown in FIG. 11, when the posture of the sensor chip 14 changes greatly, a flow rate error is caused accordingly. In particular, as the flow rate decreases (the flow rate decreases), the flow rate error increases. The broken line graph (1) shown in FIG. 11 is a flow characteristic corresponding to the posture of the sensor chip 14 shown in FIG. 10A, and the solid line graph (2) is the posture of the sensor chip 14 shown in FIG. 10B. A flow rate characteristic corresponding to the solid line graph (3) is a flow rate characteristic corresponding to the posture of the sensor chip 14 shown in FIG.

Patent Document 1 discloses a thermal flow meter that corrects the sensor output in accordance with the mounting orientation of the flow sensor.
This thermal flow meter has a zero point correction table that registers the zero point correction amount for the detection signal of the flow sensor according to the pressure of the fluid for each mounting position of the flow sensor, and the fluid passage through which the flow sensor is built. Zero point correction means for obtaining the zero point correction amount from the zero point correction table according to the flow direction and the fluid pressure and correcting the detection signal of the flow sensor, and the detection signal of the flow sensor corrected by the zero point correction means And a flow rate calculating means for determining the flow rate of the fluid flowing through the fluid passage.
According to the above configuration, since the output of the flow sensor can be zero-corrected according to the mounting posture of the flow sensor with respect to the fluid passage, it is possible to correct the change in the sensor output depending on the mounting posture of the flow sensor.

Japanese Patent No. 4150756

However, the flow sensor described in Patent Document 1 is used as an integrated flow meter such as a gas meter, for example, and the posture of the flow sensor attached to the gas pipe does not change during use. That is, only the mounting posture of the flow sensor differs depending on the direction of the gas pipe to be laid (the flow direction of the gas flowing through the gas pipe), and the posture of the flow sensor once attached to the gas pipe does not change during use.
On the other hand, for example, in an air flow meter that detects the amount of intake air taken in by an automobile engine, the posture of the flow sensor changes in accordance with the change in the posture of the vehicle body.

That is, in the flow sensor used in the automobile, even if the mounting posture of the flow sensor with respect to the intake passage of the engine is constant, the posture of the flow sensor itself changes according to the posture change of the vehicle body. For this reason, when the attitude | position of a flow sensor changes in the middle of use, it cannot respond with the prior art disclosed by patent document 1. FIG.
The present invention has been made based on the above circumstances, and an object of the present invention is to provide a thermal flow rate measuring device that can reduce a flow rate error caused by a change in posture of a flow rate sensor.

(Invention according to Claim 1)
The present invention includes a heater element that generates heat when energized, a flow rate sensor that detects a flow rate of fluid flowing through a fluid passage based on a heat radiation amount emitted from the heater element, and a posture detection that detects a change in posture of the flow rate sensor. And the flow rate error caused by the posture change of the flow rate sensor and the fluid flow rate. The flow rate error is obtained from the correlation data based on the detection result of the posture detection unit, and the fluid flow rate detected by the flow rate sensor is obtained. And a flow rate correcting means for correcting the flow rate according to the flow rate error.

  Since the thermal flow measuring device of the present invention includes posture detecting means for detecting the posture change of the flow sensor, if the posture change of the flow sensor is detected by this posture detecting means, the change in the posture of the flow sensor is detected. From the correlation data between the generated flow rate error and the fluid flow rate, the flow rate error can be obtained based on the detection result of the posture detecting means, and the fluid flow rate detected by the flow rate sensor can be corrected by the flow rate error. Thereby, since the flow volume error which arises by the attitude | position change of a flow sensor can be reduced, it can be used suitably also for the air flow meter for motor vehicles from which the attitude | position of a flow sensor changes during use, for example.

(Invention according to Claim 2)
The thermal flow rate measuring apparatus according to claim 1 is used for a vehicle equipped with an internal combustion engine, and detects an intake air amount taken in by the internal combustion engine.
Since vehicles such as automobiles often change the posture of the vehicle body during travel, the thermal flow measuring device of the present invention can be used even if the posture of the flow sensor changes as the vehicle posture changes. Since the flow rate error caused by the posture change can be corrected, the intake air amount sucked into the internal combustion engine can be detected with high accuracy.

(Invention according to claim 3)
The thermal flow rate measuring device according to claim 1 or 2, wherein the posture detecting means is a tilt sensor that detects a tilt angle of the flow rate sensor.
As an example, the posture detecting means uses a gravity applied capacitance change type inclination sensor that detects a change in the liquid level due to the inclination as a change in capacitance, converts it into an electric signal such as a voltage and outputs it. it can.

(Invention of Claim 4)
The thermal flow rate measuring apparatus according to claim 3 is characterized in that the inclination sensor is attached to the flow rate sensor or attached to a sensor housing in which the flow rate sensor is incorporated.
By attaching the tilt sensor to the flow sensor or the sensor housing, it is possible to accurately detect the change in posture of the flow sensor.

(Invention according to claim 5)
The thermal flow rate measuring apparatus according to claim 2 is characterized in that the attitude detection means is an inclination sensor provided in a vehicle.
For example, it is known to use a tilt sensor for vehicle attitude control. In this case, since the inclination sensor is previously provided in the vehicle, this inclination sensor can be used for the posture detection means of the present invention.

(Invention of Claim 6)
6. The thermal flow measuring device according to claim 1, wherein the flow rate sensor includes a sensor chip in which a membrane is formed on a part of a substrate and a heater element is disposed on the membrane, and heat generation of the heater element. A heater temperature control unit that controls the amount of current supplied to the heater element so that the temperature is higher than the temperature of the fluid flowing through the fluid passage by a certain temperature; and on the membrane on the upstream side and downstream side of the heater element with respect to the fluid flow direction Each has a resistance thermometer arranged, and has a flow rate detection unit that detects a fluid flow rate based on a temperature difference between the upstream resistance thermometer and the downstream resistance thermometer.

In the thermal type flow measuring device of the present invention, the resistance temperature detectors are arranged on the upstream side and the downstream side of the heater element, respectively, so that the forward fluid flow, that is, the fluid flowing from the upstream side to the downstream side of the heater element. In addition to the flow rate, it is also possible to detect a fluid flow rate that flows backward from the downstream side to the upstream side of the heater element.
Accordingly, when the thermal flow rate measuring device of the present invention is applied to an air flow meter (also referred to as an air flow meter) that detects the amount of intake air taken into the internal combustion engine of an automobile, the forward intake air amount taken into the internal combustion engine In addition, it is possible to accurately detect, for example, the air flow rate during backflow caused by intake pulsation.

It is sectional drawing of a thermal type flow meter. (A) The top view of a flow sensor, (b) AA sectional drawing of the same figure (a). It is a top view which shows the resistor arrange | positioned on the membrane of a sensor chip. It is a schematic diagram explaining the structure and operation | movement of an inclination sensor. It is a circuit diagram of a heater temperature control part. It is a circuit diagram of a flow rate detection unit. (A) Temperature distribution diagram showing the principle of flow rate detection, (b) Cross sectional view of the sensor chip cut along the air flow direction. It is a graph which shows the output characteristic of a thermal type flow meter. It is a block diagram of a digital calculating part. It is drawing for demonstrating the attitude | position of a flow sensor, and the influence of the heat resulting from the natural convection of a fluid. It is a characteristic view which shows the correlation with the flow volume error and fluid flow volume which arise by the attitude | position change of a flow sensor.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

Example 1
In the first embodiment, an example of a thermal flow meter 1 that detects the amount of intake air taken into the engine of an automobile will be described.
As shown in FIG. 1, a thermal flow meter 1 includes a sensor housing 2 attached to an intake passage (not shown) of an engine, a flow sensor 3 (see FIG. 2) incorporated in the sensor housing 2, and a flow rate. An inclination sensor 4 (see FIG. 4) for detecting a change in posture of the sensor 3 is provided.
First, the tilt sensor 4 will be described with reference to FIG.
The tilt sensor 4 can be incorporated into, for example, the circuit chip 5 (see FIG. 2) of the flow sensor 3 or attached to a part of the sensor housing 2.
This tilt sensor 4 has a circular oil case 4a in which about half of silicon oil as a capacitance medium is sealed, and inside this oil case 4a, there are a ring-shaped reference electrode 6 and two semi-circular shapes. Reference electrodes 7 and 8 are arranged.

The reference electrode 6 is disposed in the circumferential direction along the inner periphery of the oil case 4a, and one end thereof is taken out from the internal space of the oil case 4a as a power supply terminal 6a.
The two comparison electrodes 7 and 8 have the same area and are arranged in a state of facing each other inside the reference electrode 6, and the respective output terminals 7a and 8a are taken out from the internal space of the oil case 4a. It is. Although the reference electrode 6 shown in FIG. 4 has a ring shape, it can be formed, for example, in a disk shape so as to face the two comparison electrodes 7 and 8.
In this inclination sensor 4, capacitors A and B are formed between the reference electrode 6 immersed in silicon oil and the comparison electrodes 7 and 8, respectively, and the area ratio of the comparison electrodes 7 and 8 immersed in silicon oil changes. Then, since the capacitances of the capacitors A and B change, the change in capacitance is converted into an electric signal (analog voltage) and output from the two output terminals 7a and 8a.

For example, as shown in FIG. 4B, when the tilt sensor 4 is kept in a horizontal state, the area of the comparison electrode 7 immersed in silicon oil is equal to the area of the comparison electrode 8, and therefore each capacitor A , B have the same electrostatic capacity.
On the other hand, as shown in FIG. 4A, when the tilt sensor 4 is tilted to the left in the figure, the area of the comparison electrode 7 immersed in silicon oil is larger than that of the comparison electrode 8, and therefore the capacitor A The capacitance is larger than that of the capacitor B. On the other hand, in FIG. 4C, the area of the comparison electrode 8 immersed in silicon oil is larger than that of the comparison electrode 7, so that the capacitance of the capacitor B is larger than that of the capacitor A.
As described above, the inclination sensor 4 of the present embodiment detects a change in the attitude of the flow sensor 3 by detecting a change in the area ratio of the comparison electrodes 7 and 8 immersed in silicon oil as a change in capacitance. To do.

The sensor housing 2 is provided with a bypass passage that takes in a part of the air flowing in the intake passage from the upstream side (air cleaner side) to the downstream side (engine side), that is, the air sucked into the engine. As shown in FIG. 1, the bypass passage is a main passage communicating between an inlet 9a that opens toward the upstream side (the left side in the drawing) of the intake passage and an outlet 9b that opens toward the downstream side of the intake passage. 9 and a sub-passage 10 for taking in part of the air flowing through the main passage 9.
The main passage 9 is formed in a tapered shape in which the space between the inlet 9a and the outlet 9b is formed substantially linearly, and the channel cross-sectional area on the outlet side gradually decreases toward the outlet 9b.
The sub passage 10 is formed by communicating between a sub inlet 10 a that branches from the middle of the main passage 9 and a sub outlet 10 b that opens on the side surface of the sensor housing 2. The sub passage 10 is provided with a large bent portion in the middle of the passage, and is formed to have a passage length longer than that of the main passage 9.

The flow rate sensor 3 has functions such as a heater temperature control unit 11 (see FIG. 5), a flow rate detection unit 12 (see FIG. 6), and a digital calculation unit 13 (see FIG. 9), which will be described later. The circuit chip 5 and the sensor chip 14 (see FIG. 2) are provided. The circuit chip 5 and the sensor chip 14 are integrally accommodated in a common resin case 15 and configured as a sensor assembly.
As shown in FIG. 2B, the sensor chip 14 has a membrane 16 formed on a part of the sensor substrate 14a. The membrane 16 is an insulating film formed on the surface of the sensor substrate 14a by sputtering, CVD, or the like. For example, the sensor substrate 14a is formed from the back surface of the sensor substrate 14a to the boundary surface with the insulating film by anisotropic etching. Is formed by removing a part of the cavity 14b.

As shown in FIG. 3, the sensor chip 14 has a heater element 17, an indirectly heated resistor 18, and a resistance temperature detector 19 disposed on the surface of the membrane 16. An intake air temperature detection resistor 20, a first resistor 21, and a second resistor 22 are disposed. The heater element 17 is disposed substantially at the center of the membrane 16 and is controlled to a reference temperature by the heater temperature control unit 11.
The indirectly heated resistor 18 is disposed in proximity to surround the heater element 17 and detects the temperature of the heater element 17.
As shown in FIG. 3, the resistance temperature detector 19 includes two resistance temperature detectors 19 (first resistance temperature detectors) arranged on the upstream side (left side in the drawing) of the heater element 17 with respect to the air flow direction. 19a, the second resistance temperature detector 19b), and two resistance temperature detectors 19 (the first resistance temperature detector 19c and the second resistance temperature detector 19d) disposed on the downstream side of the heater element 17. .

The intake air temperature detection resistor 20 is disposed in the thick portion of the sensor substrate 14a where the cavity portion 14b is not formed, and detects the intake air temperature (the temperature of the air flowing through the sub passage 10). The intake detection resistor 20 is disposed at a position away from the heater element 17 by a predetermined distance so that the heat of the heater element 17 does not affect the temperature detection.
Like the intake air temperature detection resistor 20, the first resistor 21 and the second resistor 22 are arranged in the thick portion of the sensor substrate 14a and are not affected by the heat of the heater element 17 so that they are not affected by the heat. It is arranged at a position away from the 17 by a predetermined distance. One or both of the first resistor 21 and the second resistor 22 can be provided on the circuit chip 5.
The heater element 17, the indirectly heated resistor 18, the resistance temperature detector 19, the intake air temperature detection resistor 20, the first resistor 21, and the second resistor 22 are formed into thin films by a film forming technique such as sputtering or vapor deposition. After forming, it can be formed by patterning into a desired shape by etching. As a material for the resistor, for example, it is desirable to use highly reliable platinum.

As shown in FIG. 5, the heater temperature control unit 11 is turned on / off based on a bridge circuit to be described later, an operational amplifier 25 connected to two midpoint terminals 23 and 24 of the bridge circuit, and an output of the operational amplifier 25. The transistor 26 is turned off, and the temperature of the heater element 17 is controlled to a reference temperature that is higher than the intake air temperature by a predetermined temperature (for example, 200 ° C.).
The bridge circuit has two bridge arms connected between the power supply terminal 27 and the ground terminal 28, and one bridge arm includes an indirectly heated resistor 18 that detects the temperature of the heater element 17, and a first thermal arm 18. Are connected in series, and the other bridge arm is connected in series with an intake air temperature detection resistor 20 for detecting the intake air temperature and a second resistor 22.
For example, when the temperature of the heater element 17 or the intake air temperature changes and the balance of the bridge circuit is lost, the heater temperature control unit 11 controls the current flowing through the heater element 17 to restore the original balance state. work.

  More specifically, for example, when the temperature of the heater element 17 is lower than the reference temperature, the resistance value of the heater element 17 is reduced and a potential difference is generated between the two midpoint terminals 23 and 24 of the bridge circuit. , The transistor 26 is turned on. As a result, a current flows from the power source 29 to the heater element 17 and the temperature of the heater element 17 rises. Thereafter, when the temperature of the heater element 17 rises to the reference temperature, the potential difference between the two midpoint terminals 23 and 24 disappears, that is, the balance of the bridge circuit is maintained, whereby the transistor 26 is turned off and the heater element 17 is turned off. The current supplied to is cut off. As a result, the temperature of the heater element 17 is maintained at the reference temperature.

As shown in FIG. 6, the flow rate detection unit 12 is connected to a bridge circuit formed by arranging four resistance temperature detectors 19 on each side, and two midpoint terminals 30 and 31 of the bridge circuit. An upstream operational resistor 32 (a first resistance temperature detector 19a, a second resistance temperature detector 19b) and a downstream resistance temperature detector 19 (a first resistance temperature detector 19c). The intake air amount is detected from the temperature difference from the second resistance temperature detector 19d).
The bridge circuit of the flow rate detection unit 12 has two bridge arms between a power supply terminal 33 to which a predetermined voltage is applied and a ground terminal 34 connected to the ground, and one bridge arm has a heater. A first resistance temperature detector 19a upstream of the element 17 and a first resistance temperature detector 19c downstream are connected in series, and the other bridge arm has a second resistance temperature detector downstream of the heater element 17. The body 19d and the upstream second resistance temperature detector 19b are connected in series.

Here, the relationship between the amount of heat released from the heater element 17 and the temperature detected by the resistance temperature detector 19 will be described with reference to FIG.
When no air flow is generated in the sub-passage 10, the temperature distribution is symmetric between the upstream side and the downstream side around the heater element 17, as shown by the broken line graph in FIG. There is no temperature difference between the temperature resistors 19a and 19b and the downstream temperature measuring resistors 19c and 19d.
On the other hand, when a forward air flow is generated in the sub-passage 10, the upstream resistance temperature detectors 19a and 19b have a cooling effect by the air flow than the downstream resistance temperature detectors 19c and 19d. Therefore, as shown by the solid line graph in FIG. 7A, a temperature distribution biased toward the downstream side (right side in the drawing) of the heater element 17 occurs. That is, the temperature sensing resistors 19a and 19b on the upstream side have lower detection temperatures than the temperature sensing resistors 19c and 19d on the downstream side.
On the other hand, when an air flow in the reverse direction is generated in the sub-passage 10, a temperature distribution that is biased toward the upstream side of the heater element 17 is generated, so that the upstream resistance temperature detectors 19a and 19b are more downstream. The detected temperature is higher than 19c and 19d.

As described above, when an air flow is generated in the sub-passage 10, as shown in FIG. 8, detection of the temperature measuring resistors 19a and 19b on the upstream side is performed according to the air flow rate (intake amount) and the air flow direction. Since a temperature difference ΔT occurs between the temperature and the temperature measured by the resistance bulbs 19c and 19d measured downstream, the intake air amount and the air flow direction can be detected from the temperature difference ΔT.
When there is a temperature difference ΔT between the detected temperature of the upstream resistance temperature detectors 19a and 19b and the detected temperature of the downstream resistance temperature detectors 19c and 19d, that is, the upstream resistance temperature detector 19a. , 19b and the resistance values of the resistance bulbs 19c, 19d on the downstream side change, and a potential difference is generated between the two midpoint terminals 30, 31 of the bridge circuit. Amplified and output to the digital calculation unit 13.

The digital operation unit 13 is configured in the circuit chip 5 and, as shown in FIG. 9, an A / D converter 35 that digitally converts a voltage signal (analog value) corresponding to the intake air amount detected by the flow rate detection unit 12. A / D converter 36 that digitally converts the detection signal (analog voltage) of the tilt sensor 4 and a flow rate correction unit 37 (described below) that corrects a flow rate error caused by a change in posture of the flow rate sensor 3 are corrected. A signal output unit 38 for converting the flow rate signal (voltage value) into a frequency value and outputting the frequency value to an external ECU (not shown). The signal output unit 38 may be configured to output the voltage value as it is to the ECU without converting the voltage value into a frequency value.
The flow rate correction unit 37 has a correction map in which correlation data (see FIG. 11) between the flow rate error caused by the change in the attitude of the flow rate sensor 3 and the intake air amount is recorded, and based on the detection result of the inclination sensor 4 based on this correction map. The flow rate error is obtained, and the intake air amount detected by the flow rate sensor 3 is corrected according to the flow rate error.

(Operation and Effect of Example 1)
Since the thermal type flow meter 1 of the present embodiment includes the inclination sensor 4 that detects a change in the posture of the flow sensor 3, even if the posture of the flow sensor 3 changes during use, the posture of the flow sensor 3 can be changed. By detecting, flow volume correction can be performed. That is, when a change in the attitude of the flow sensor 3 is detected by the inclination sensor 4, the detection result of the inclination sensor 4 is obtained from a correction map that records correlation data between the flow rate error caused by the change in the attitude of the flow sensor 3 and the intake air amount. On the basis of the flow rate error, the intake air amount detected by the flow rate sensor 3 can be corrected by the flow rate error.
As a result, the flow rate error caused by the change in the posture of the flow rate sensor 3 can be reduced, so that the intake air amount sucked into the engine can be detected with high accuracy. In particular, it can be suitably used as a thermal flow meter 1 for automobiles in which the attitude of the flow sensor 3 changes with the attitude change of the vehicle body during traveling.

(Modification)
In the first embodiment, it is described that the tilt sensor 4 is incorporated in the circuit chip 5 of the flow sensor 3 or attached to a part of the sensor housing 2. For example, the tilt sensor 4 is used for posture control of the vehicle body. In the vehicle, it is not necessary to newly provide the inclination sensor 4, and the already provided inclination sensor 4 can be used for the posture detection means of the present invention.
In the first embodiment, the flow rate correction unit 37 is provided in the digital calculation unit 13, but a configuration in which the function of the flow rate correction unit 37 is provided to an external ECU may be used.

In the flow rate sensor 3 described in the first embodiment, the resistance temperature detectors 19 are arranged on the upstream side and the downstream side of the heater element 17 respectively, but only one of the upstream side and the downstream side of the heater element 17 is temperature measured. The structure which has arrange | positioned the resistor 19 may be sufficient.
The heater temperature control unit 11 described in the first embodiment includes an indirectly heated resistor 18 and a first resistor 21 that detect the temperature of the heater element 17, and an intake air temperature detection resistor 20 and a second resistor that detect the intake air temperature. Although the bridge circuit is comprised with the resistor 22 of this, the indirectly heated resistor 18 can also be abolished. In this case, a bridge circuit may be configured by replacing the indirectly heated resistor 18 with the heater element 17.

1 Thermal flow meter (thermal flow measurement device)
2 Sensor housing 3 Flow rate sensor 4 Tilt sensor (Attitude detection means)
DESCRIPTION OF SYMBOLS 11 Heater temperature control part 12 Flow volume detection part 13 Digital operation part 14 Sensor chip 14a Sensor substrate (board | substrate)
16 Membrane 17 Heater Element 19 Resistance Temperature Detector 37 Flow Rate Correction Unit (Flow Rate Correction Means)

Claims (6)

A flow sensor that includes a heater element that generates heat when energized and detects the flow rate of fluid flowing through the fluid passage based on the amount of heat released from the heater element;
Attitude detection means for detecting the attitude change of the flow sensor;
It has correlation data between the flow rate error caused by the posture change of the flow rate sensor and the fluid flow rate. The flow rate error is obtained from the correlation data based on the detection result of the posture detection means, and the fluid flow rate detected by the flow rate sensor is obtained. A thermal flow rate measuring device comprising flow rate correction means for correcting the flow rate according to the flow rate error. The thermal flow rate measuring device according to claim 1 is:
A thermal type flow rate measuring apparatus used for a vehicle equipped with an internal combustion engine and detecting an intake air amount sucked by the internal combustion engine. In the thermal type flow measuring device according to claim 1 or 2,
The thermal flow measurement device according to claim 1, wherein the posture detection means is a tilt sensor that detects a tilt angle of the flow sensor. In the thermal type flow measuring device according to claim 3,
The thermal sensor according to claim 1, wherein the inclination sensor is attached to the flow sensor or is attached to a sensor housing in which the flow sensor is incorporated. In the thermal type flow measuring device according to claim 2,
The thermal flow rate measuring apparatus according to claim 1, wherein the posture detecting means is a tilt sensor provided in the vehicle. In any one thermal flow measuring device according to claims 1 to 5,
The flow sensor
A membrane is formed on a part of the substrate, and a sensor chip in which the heater element is arranged on the membrane;
A heater temperature control unit for controlling an energization amount to the heater element so that a heat generation temperature of the heater element is higher than a temperature of the fluid flowing through the fluid passage by a certain temperature;
A temperature measuring resistor disposed on the upstream side and the downstream side of the heater element on the membrane with respect to a fluid flow direction; the temperature measuring resistor on the upstream side and the temperature measuring resistor on the downstream side; And a flow rate detecting unit for detecting a fluid flow rate based on the temperature difference between the two.

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