KR0184928B1 - Suction air flow detector - Google Patents

Abstract

Provided is an intake air flow rate detection device that can improve detection accuracy by correcting a detection signal from a detection element when a drift or reverse flow occurs in the intake passage.

In the casing 32, the first and second thermal elements 33 and 34 are provided to be spaced apart from the front and rear of the heating wire resistance 12, and the third and fourth feelings are spaced apart so as to sandwich the heating wire resistance 12 in the radial direction. Install the body 35, 36. When the second thermostat 34 on the downstream side of the intake passage becomes higher than the first thermostat 33 on the upstream side, the flow of intake air is in the forward direction, and the downstream thermostat 34 on the upstream side. If the temperature is lower than the temperature sensing member 33, the flow of the intake air is determined in the reverse direction, and correction is performed. In addition, by comparing the outputs of the third thermal element 35 and the fourth thermal element 36, the presence or absence of the deflection of the intake air is detected, and if there is the deflection, the deflection is corrected to calculate an accurate intake air flow rate. .

Description

Intake Air Flow Detection Device

1 is a configuration diagram of a casing, a hot wire resistance, a respective thermosensitive member, and the like showing an intake air flow rate detection device according to a first embodiment of the present invention.

2 is an enlarged cross-sectional view in the direction of arrow II-II in FIG. 1;

3 is a block diagram showing a heating wire resistance, a thermostat, a control unit, and the like.

4 is a flowchart showing a detection processing operation of the intake air flow rate according to the first embodiment.

5 is a flowchart showing a detection processing operation of the intake air flow rate according to the second embodiment.

6 is a longitudinal sectional view showing an intake air flow rate detection device according to the prior art.

7 is an enlarged perspective view showing the flow meter body.

8 is a partial cross-sectional view of the flowmeter body shown in FIG.

9 is an explanatory view of the operation of the intake air flow rate detection device according to the prior art.

FIG. 10 is an operation explanatory diagram similar to FIG. 8 showing a state in which intake air flows back. FIG.

11 is a characteristic diagram showing the relationship between the flow rate of intake air and time.

12 is a characteristic diagram showing a detection signal of intake air according to FIG.

* Explanation of symbols for main parts of the drawings

3: flow meter main body 12: hot wire resistance (detection element)

31: intake air flow detection device 32: casing

33: the first thermostat 34: the second thermostat

35: third thermal element 36: fourth thermal element

37: control unit

The present invention relates to an intake air flow rate detection device suitably used for detecting an intake air flow rate, for example, an automobile engine.

In general, an automobile engine or the like is used to combust a mixture of fuel and intake air in a combustion chamber of an engine main body so as to obtain a rotational output of the engine from the combustion pressure, and detect the intake air amount after calculating the injection amount of the fuel. Is an important factor.

Thus, the intake air flow rate detection apparatus of the prior art is shown in FIG. 6 and FIG.

In the drawing, reference numeral 1 denotes a hot wire type intake air flow rate detection device, and the intake air flow rate detection device 1 communicates with the intake side of the engine as shown in FIG. It consists of a tubular casing 2 constituting a part of the flowmeter and a flow meter body 3 described later provided in the connection hole 2A of the casing 2.

Reference numeral 3 denotes a flowmeter body formed by means such as an insert mold, and the flowmeter body 3 is wound around a winding resistance (not shown) serving as a reference resistance as shown in FIG. The winding end 4 is attached to the end and is formed in the circumferential shape, the terminal part 5 formed on the axial side of the winding part 4 and formed in a substantially disk shape, and the winding part 4 from the winding part 4 to the other side in the axial direction. It is formed in a substantially U-shape and is formed of a detection holder 6 in which a hot wire resistor 12 and a temperature compensation resistor 13 described later are disposed, and a circuit casing 7 described later. Terminal portions 4A and 4B are formed on both sides of 4).

Reference numeral 7 denotes a circuit casing provided on the outer circumferential side of the casing 2 so as to close the connection hole 2A of the casing 2, and the circuit casing 7 is made of an insulating resin material. The bottom portion is provided with a fitting portion 7A fitted to the connection hole 2A of the casing 2. The circuit casing 7 includes an insulating substrate (not shown) made of, for example, a ceramic material, a flow rate regulating resistor, an OP amplifier, a linearizer (not shown anywhere), or the like mounted on the substrate. It is built in.

Reference numerals 8, 9, 10, and 11 denote the first, second, third, and fourth terminal plates integrally formed with the flowmeter body 3 and embedded in the flowmeter body 3, and the terminal plate 8 11 is a terminal pin whose one end side as shown in FIG. 8 protrudes from the terminal portion 5 in the axial direction, and is detachably connected to a connector portion (not shown) of the circuit casing 7. 8A, 9A, 10A, 11A). Here, the other end side of the first terminal plate 8 is a terminal 8B which projects radially outward from the winding portion 4 and is connected to one side of the winding resistance.

On the other end side of the second terminal plate 9, it protrudes radially outward from the winding portion 4 to form a pair with the terminal 8B, and the terminal 9B to which the other side of the winding resistance is connected, and the detection holder ( The terminal 9C which extends to the middle of 6), protrudes in the radial direction, and is connected to one side (negative side) of the heating wire resistance 12 is provided. On the other side of the third terminal plate 10, the terminal 10B protrudes radially from the detection holder 6 to form a pair with the terminal 9C, and the other side (plus side) of the heating wire resistor 12 is connected. And a terminal 10C which branches from the terminal 10 to protrude in the radial direction from the detection holder 6 and to which the other side (plus side) of the temperature compensation resistor 13 is connected. Moreover, the 4th terminal board 11 protrudes radially from the detection holder 6 so that the other end side may be grouped with the terminal 10C, and the terminal (one side) of the temperature compensation resistor 13 is connected ( 11B).

In this manner, the hot wire resistor 12 is connected between the terminals 9C and 10B by means of soldering or the like, and the temperature compensation resistor 13 is connected between the terminals 10C and 11B by means of soldering or the like. It is becoming. The hot wire resistor 12 and the temperature compensating resistor 13 form a bridge circuit together with the winding resistance and the flow regulating resistor disposed in the circuit casing 7.

Reference numeral 12 denotes a hot wire-type hot wire resistance constituting the detection element of the intake air flow rate, and this hot wire resistance 12 is made of a material such as platinum, which reacts sensitively to temperature change and whose resistance value changes. It is formed of a small-diameter resistive element formed by winding a platinum wire or depositing a platinum thin film on an insulating cylindrical body made of, for example, ceramic. The hot wire resistor 12 is heated by energization from a battery (not shown), for example, to about 240 ° C., and cooled by air flowing in the casing 2, thereby reducing the air flow rate in the casing 2. To detect.

Reference numeral 13 denotes a temperature compensation resistor, and the temperature compensation resistor 13 deposits a platinum thin film by means of sputtering or the like on an insulating thin substrate made of a ceramic material such as alumina, for example. The electrodes are formed by connecting the terminals 10C and 11B to both ends of the platinum thin film.

Reference numeral 14 denotes a protective cover mounted on the detection holder 6 in order to protect the hot wire resistance 12 and the temperature compensation resistor 13, which protective cover 14 is formed almost in a shape. After the hot wire resistor 12 and the temperature compensation resistor 13 are mounted on the detection holder 6, as shown by arrows in FIG. 7, the hot wire resistor 12 and the temperature compensation resistor 13 are deposited. At the same time as the protection, the intake air is allowed to flow. In addition, in FIG. 6, the protection cover 14 is shown in the state which removed the protection cover 14 in order to specify the hot wire resistance 12 and the temperature compensation resistance 13. As shown in FIG.

The intake air flow rate detection device 1 according to the prior art has a configuration as described above, and the intake air flow rate detection device 1 has another structure in which the casing 2 is connected to both ends as shown in FIG. An intake passage is formed together with the tubular members 15 and 16, and the right side of the tubular member 16 is connected to an air cleaner (not shown) to clean air (outside air) in a cylinder connected to the left side of the tubular member 15. And suction in the direction of arrow A in accordance with the reciprocating operation of the piston (not shown anywhere).

Here, the hot wire resistance 12 is disposed on the central axis of the casing 2, and the average flow velocity is calculated by a control unit (not shown) by detecting the flow velocity V1 or V2 of the air passing through the central axis. The following formula for calculating the flow rate Q from the average flow rate V0 and the cross-sectional area S,

[Equation 1]

Q = S × V0

Intake air flow rate is detected from the

That is, since the intake passages made of the casing 2, the pipe members 15, 16, and the like extend in a straight line, the intake air flow circulating therein becomes symmetrical with respect to the central axis of the intake passage, and the flow velocity distribution thereof. As shown by the dashed-dotted line in FIG. 9, when it becomes delayed, it becomes flow velocity distribution F1, and if it becomes early, it becomes flow velocity distribution F2. Since the hot wire resistance 12 is cooled as the flow rates V1 and V2 of the intake air become faster, and the resistance value changes, for example, the flow rates V1 and V2 passing through the center axis among the flow rate distributions F1 and F2 are described above. It detects as a change in resistance value, and calculates the average flow velocity of flow velocity distribution F1, F2 from this flow velocity V1, V2, and detects intake air flow volume.

By the way, in the above-described prior art, the intake air flow rate is detected in accordance with the change in the resistance value when the heating wire resistance 12 is cooled based on the intake air flow rates V1, V2 and the like, but the intake air always distributes the flow rate in FIG. It is not limited to flow in the intake passage in a flow velocity symmetrical with respect to the central axis as in F1 and F2, and is inclined like a flow rate distribution F3 due to the layout of the intake passage (hereinafter referred to as "drift"). In this case, there is a problem that the distribution of the flow velocity in the intake passage is disturbed and the error of detection by the hot wire resistance 12 is increased.

In addition, the intake air circulating in the intake passage is also sucked into each cylinder when each intake valve (not shown) is opened as each piston reciprocates in the cylinder of the multi-cylinder, so that the intake air is in the intake passage. At the position of the heating wire resistance 12, the intake valve opens before closing the exhaust valve due to the overlap of the engine's exhaust valve (not shown) and the intake valve. It may return to the intake passage from the intake valve.

In addition, even if the intake stroke ends and the compression stroke starts, the intake valve is not completely closed yet, and part of the intake air once sucked into the cylinder flows back through the intake valve in the direction of arrow B as shown in FIGS. 6 and 11. In this case, the flow rate V at this time is temporarily negative as in the portions 18A, 18B, ... of characteristic 18, and the intake air is reversed as indicated by the flow rate distribution F4 in FIG. 10 in the intake passage. It may flow down.

For this reason, the hot wire resistance 12 is cooled by the intake air flow flowing in the forward direction with the cylinder side of the engine, and the reverse direction indicated by the flow rate V3 in FIG. 10 is also cooled by the air flow. Is added redundantly to the intake air flow rate, the detection signal q of the intake air flow rate is redundantly detected like the portions 19A and 19B of characteristic 19 illustrated in FIG. 12, and the problem that detection accuracy is lowered. have.

The present invention has been made in view of the above-described problems of the prior art, and the present invention can correct a detection signal from a detection element even when drift or reverse air flow occurs in the intake passage due to reflux of the exhaust, or the like. It is an object of the present invention to provide an intake air flow rate detection device capable of improving detection accuracy.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, in invention of Claim 1, the cylindrical casing provided in the middle of an intake path, the detection element of the intake air flow volume provided in this casing, and spaced apart back and front of the said detection element with respect to the flow direction of intake air. And the first and second thermosensitive bodies which are installed in the casing and detect the temperature change due to the flow of intake air, and are spaced apart from the detection element in a direction different from the first and second thermosensitive bodies respectively. It is provided in the inside, and the structure which consists of the 3rd and 4th thermosensitive bodies which detect the temperature change by the said intake air flow is employ | adopted.

In the invention according to claim 2, flow direction determining means for determining whether the flow direction of the intake air is in the forward direction or the reverse direction on the basis of the detection signals from the first and second temperature sensing bodies, and the third and fourth temperature reductions. On the basis of the detection signal from the sieve, a configuration is provided that includes the deflection determination means for determining whether the flow of the intake air is in the deflection state.

In addition, the invention according to claim 3 includes detection operation stop means for temporarily stopping the detection operation of the intake air flow rate by the detection element when the flow direction determination means determines that the intake air flow direction is in the reverse direction. We adopt constitution.

In the invention according to claim 4, the flow rate detection value of the intake air flow rate by the detection element is corrected on the basis of the detection signals from the first and second thermosensitive members when determined by the flow direction detection means in the reverse direction. The structure which comprises a backflow correction means is employ | adopted.

In the invention according to claim 5, the flow rate detection value by the detection element is corrected on the basis of the detection signals from the third and fourth thermal elements when the flow of intake air is determined to be in the state of drift by the drift determination means. The structure which comprises the drift correction means mentioned above is employ | adopted.

According to the above configuration, when the intake air is in the forward direction, the thermosensitive member located at the front side (upstream side) of the detection element is cooled more than the thermosensitive member at the rear side (downstream side). If the temperature sensitive element on the upstream side is lower than the temperature sensitive element on the downstream side, it can be determined that the flow of air is forward. If the temperature sensitive element on the downstream side is lower than the temperature sensitive element on the upstream side, the flow of air reverses. Can be determined. Moreover, the presence or absence of the drift of intake air can be detected by comparing the temperature of each 3rd and 4th thermosensitive body.

Then, when it is determined that the inflow direction of the intake air is in the reverse direction as in the invention of claim 3, the detection operation stop means temporarily stops the detection operation of the intake air flow rate so that the reverse flow rate in the intake air is overlapped with the intake air direction. Can be prevented.

According to the invention of claim 5, when there is a deviation in the flow of the intake air, the flow rate correction value of the intake air amount can be corrected according to the drift state by the drift correction means.

Embodiments of the present invention will be described below with reference to FIGS. In addition, in the Example, the same code | symbol is attached | subjected to the same component as the prior art mentioned above, and the description is abbreviate | omitted.

First, Figs. 1 to 4 show the first embodiment.

In the drawing, reference numeral 31 denotes an intake air flow rate detection device according to the present embodiment, and this intake air flow rate detection device 31 is substantially the same as that according to the conventional art described above, and has a cylindrical casing 32. ) And a flowmeter body 3 provided in the casing 32 so that the hot wire resistance 12 as a detection element is located at the center of the casing 32. The casing 32 has a thermosensitive member described later. (33, 34, 35, 36) are arranged concentrically around the imaginary circle C centered on the hot wire resistance 12 at equal intervals. And this casing 32 is connected to the cylinder (not shown anywhere) provided in the left and right end sides of a figure, and comprises a part of intake passage, arrow A direction from the left side of this casing 32 to the right side. Intake air flows in (forward direction).

Reference numeral 33 denotes a first thermostat installed on the front side (upstream side) of the heating wire resistance 12 with respect to the flow direction of the intake air, and reference numeral 34 denotes the heating wire resistance 12 of the flowmeter body 3. A second thermosensitive member spaced apart from the thermosensitive member 33 to the right side (downstream side) is displayed, and the thermosensitive members 33 and 34 are formed of, for example, a heat generating resistor made of platinum wire or the like. As shown in Fig. 6, the control unit 37 is connected to an input side of the control unit 37 described later. Each of the thermosensitive members 33 and 34 generates heat to a predetermined temperature by applying a voltage from the outside, and the resistance value changes as it cools down with the air flow in the casing 32, thereby changing the temperature change caused by the flow of the intake air. As a change in the resistance value, outputs Ta and Tb corresponding to respective temperatures are output toward the control unit 37 described later. Here, when intake air flows in the forward direction, the output Ta becomes larger than the output Tb, and when a reverse flow occurs in the intake air, this relationship is reversed and the output Ta becomes smaller than the output Tb.

Reference numerals 35 and 36 denote the third and fourth thermal elements installed on the casing 32 by being spaced apart from each other so as to sandwich the heating wire resistors 12 up and down, and each of the thermal elements 35 and 36 is described above. The same heat generating resistors as those of the respective thermosensitive members 33 and 34 are used, and are connected to the input side of the control unit 37 as shown in FIG. Each of the thermosensitive members 35 and 36 detects a temperature changing according to the flow of air flowing around, as a change in resistance value, and outputs outputs Tc and Td corresponding to the respective temperatures toward the control unit 37. . Here, when no drift occurs, the output Tc and the output Td become the same, and when the drift occurs, a difference occurs between the output Tc and the output Td.

Reference numeral 37 denotes a control unit constituted by a microcomputer or the like, on which the heating wire resistor 12 and the respective thermosensitive members 33, 34, 35, 36 are connected to an input side of the control unit 37, The control unit 37 stores the program shown in FIG. 4 in a storage device such as a ROM, and moves backward in the intake passage in the case where drift occurs in the intake passage or by reflux of the exhaust or pulsation in the high load region of the engine. When the air flow is generated, the detection signal q is processed to the correction value q '(calculated) as the flow rate detection value from the heat ray resistance 12.

Reference numeral 38 denotes an injection valve installed in connection with the output side of the control unit 37, which injects an amount of fuel corresponding to the intake air flow rate calculated by the control unit 37. It is intended to inject into the engine.

The intake air flow rate detection device according to the present embodiment has the configuration as described above, and the basic detection operation for detecting the intake air flow rate based on the flow rate V detected by the heating wire resistance 12 is special and that of the prior art. There is no difference.

Therefore, the detection processing operation of the intake air flow rate by the control unit 37 will be described with reference to FIG. 4.

First, when the processing operation is started in the program shown in FIG. 4, in step 1, the output Ta is compared by comparing the output Ta read from the first thermosensitive member 33 with the output Tb read from the second thermosensitive member 34. It is determined whether or not larger than the output Tb, and when it is determined as "YES", the air flow can be determined as the forward direction (arrow A direction).

In step 2, it is determined whether the output Tc of the third thermosensitive member 35 and the output Td of the fourth thermosensitive member 36 are the same, and if it is determined as "YES", the control proceeds to step 3. Here, when the output Tc and the output Td are the same, since the drift does not occur in the intake air flow in the casing 32, in step 3, the detection signal q of the hot wire resistance 12 is directly applied to the correction value q '.

[Equation 2]

q '= q

As shown in Fig. 2, the process proceeds to Step 4 without performing the drift correction. Step 4S adds the correction value q 'every unit time to find the flow rate Q corresponding to the actual amount of intake air, and moves to Step 5 to return. After that, the process after Step 1 is repeated again.

On the other hand, when it is determined as "NO" in the step 1, since backflow is occurring in the intake air in the casing 32, the flow advances to step 6 to detect the flow rate from the hot wire resistance 12 (reading operation). Pause. And the detection signal q at this time is made into the correction value q '.

[Equation 3]

q '= 0

Is read and the process moves to step 4. As a result, it is possible to prevent the flow rate from being overlapped with the intake air amount in the reverse direction.

In addition, when it determines with "NO" in step 2, since it is a case where drift has generate | occur | produced in the intake air in the casing 2, the detection signal q from the heat ray resistance 12 is output from the 3rd thermosensitive body 35. In addition, in FIG. Based on Tc and the output Td from the fourth thermostat 36

[Equation 4]

q '= F (q, c, d)

This calculation is performed to find the correction value q '. Here, the calculation formula of Equation 4 is determined by, for example, a correction map (not shown) created by examining the relationship between the measured intake air flow rate and the detection signal q, the output Tc, and Td.

In this way, according to this embodiment, even if the intake air flows back in the casing 32 and is cooled again by the intake air in which the heating wire resistance 12 flows back, the detection operation of the intake air flow rate is temporarily stopped to thereby reverse the flow. It is possible to prevent double counting of the air volume into the intake air flow rate, and also to perform inflection correction even when the air flow becomes the drift state so that the intake air amount corresponding to the actual flow rate can be detected. Can be surely improved.

In the first embodiment, among the programs shown in FIG. 4, Step 1 shows a specific example of the flow direction determining means which is a constituent requirement of the present invention, and Step 2 shows a specific example of the drift determining means. 6 shows a specific example of the detection operation stopping means, and step 7 shows a specific example of the drift correction means.

Next, Fig. 5 shows a second embodiment of the present invention, which is characterized by searching for the drift correction means at the rear end of the reverse flow determining means. In the present embodiment, the same components as in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted, and the difference between the intake air flow rate detection device according to the present embodiment and the first embodiment is different. Since is in the program stored in the control unit, the operation of detecting the intake air flow rate by the control unit will be described here with reference to FIG.

First, the processing operation is started, and in step 11, the output Ta read out from the first thermosensitive member 33 is compared with the output Tb read out from the second thermosensitive member 34 to determine whether the output Ta is higher than the output Tb. If it is determined that "YES", the process proceeds to Step 12.

In step 12, the output Tc read out from the third thermosensitive member 35 is compared with the output Td read out from the fourth thermosensitive member 36, and when it determines with "YES", it moves to step 13, and it heats in step 13 The detection signal q of the resistor 12 is moved to step 14 as a correction value q 'as it is. In step 14, the correction value q 'is added for each unit of time, the flow rate Q is obtained, the flow proceeds to step 15, and the processing subsequent to step 11 is repeated.

On the other hand, when it determines with "NO" in step 12, it progresses to step 16 and performs the same drift correction as the thing by Formula 4 described in the said 1st Example, and it moves to step 14.

In addition, when it determines with "NO" in step 11, it moves to step 17 and determines whether the output Tc and the output Td are the same. And in step 17, when it determines with "YES", since it is a state which the deflection does not generate | occur | produce in the air flow (backflow) which flows in the casing 32 in the opposite direction to the arrow C direction, intake air in the casing 32 Since the flows are the same, the sign of the detection signal q of the heating wire resistor 12 is reversed.

[Equation 5]

q '= -q

The calculation of the phosphorus correction value q 'is performed, and it moves to step 14. Thereby, redundancy can be subtracted from the intake air flow rate which was cooled by the air stream in which the hot wire resistance 12 was reversed, and double-added, and the detection error of the intake air flow rate can be made small, and the precision can be improved.

In the case where it is determined as "NO" in step 17, the flow is reversed in the reverse air flow, and unless the flow rate correction is performed, the flow rate due to the reverse flow is not detected accurately.

[Equation 6]

q '= -f (q, c, d)

The phosphorus correction operation is performed to perform the process of Step 14 as described above.

Here, the expression of the expression 6 is similar to the expression of the expression 4 described above, for example, by a correction map (not shown) created by examining the relationship between the measured intake air flow rate and the detection signal q, the output Tc, and Td. Is determined.

In this way, the present embodiment configured as described above also obtains almost the same operational effects as the first embodiment. However, in the present embodiment, backflow correction is performed by the process of step 18, and in step 19, the backflow is reversed. Since the correction is performed, even if a reverse flow occurs in the intake air, the reverse flow correction can be performed to correct the detection signal q of the flow rate as shown in Equation 5 above, and at the same time, the flow of air reverse in the reverse direction is corrected even if the deflection occurs. It can correct by means, and the detection accuracy of intake air flow volume can be improved significantly.

In the second embodiment, among the programs shown in FIG. 5, Step 11 shows a specific example of the flow direction determining means, which is a constituent requirement of the present invention, and Steps 12 and 17 show a specific example of the deflection determining means. 16 and 19 show specific examples of the drift correction means.

In each of the above embodiments, four first to fourth thermosensitive members 33, 34, 35, and 36 are provided at equal intervals around the virtual circle C centered on the hot wire resistance 12. This invention is not limited to this, For example, you may provide 6 or 8 thermostats on the virtual circle C at equal intervals, or the 1st, 2nd thermostats 33 and 34 may be virtual circles. It may be moved inward or outward of C, and may move closer to or away from the hot wire resistance 12. Moreover, you may transfer other thermosensitive bodies 35 and 36 to the front (upstream) side or the back (downstream) side rather than the heating wire resistance 12, and to install. The gist may be arranged so that the distance from the hot wire resistance 12 is constant in the radial direction of the casing 32.

As described above, the intake air flow rate detection device according to the present invention separates the first and second thermosensitive bodies spaced apart before and after the detection elements, and in the direction different from the first and second thermosensitive bodies, respectively. By providing the third and fourth thermostats, when the thermostats located upstream of the intake passage among the first and second thermostats have a lower temperature than the thermostats on the downstream side, the flow of intake air is forward. It can be determined, and when the downstream thermosensitive member is at a temperature lower than that of the upstream thermostat, it can be determined that the flow of intake air is in the reverse direction. And since the presence or absence of the drift of intake air can be detected by comparing the temperature of each of the 3rd and 4th thermostats, when there exists a backflow or a drift in the flow of intake air, by correcting and calculating the drift or the backflow component Accurate intake air volume can be detected.

In addition, as in the invention of claim 3, when the flow direction of the intake air is determined to be in the reverse direction, the detection operation of the intake air flow rate is temporarily stopped, thereby preventing the flow rate of the reverse direction in the intake air from being overlapped with the intake air amount. And the flow rate detection accuracy can be improved.

In addition, as in the invention of claim 4, when there is a deviation in the flow of intake air, the reverse flow correction is performed by the reverse flow correction means, so that the reverse flow rate of the intake air amount can be corrected, so that the correct flow rate can always be detected.

On the other hand, as in the invention of claim 5, when there is a deviation in the flow of the intake air, the drift correction is performed by the drift correction means, so that the drift portion of the intake air amount can be corrected and the accurate flow rate can always be detected.

Claims (5)

A cylindrical casing provided in the middle of the suction passage, a detection element of the intake air flow rate provided in the casing, spaced in front and rear of the detection element with respect to the flow direction of the intake air, and installed in the casing, and the temperature caused by the flow of the intake air. First and second thermosensitive bodies for detecting a change, and spaced apart from the detection elements in different directions from the respective first and second thermosensitive bodies, and installed in the casing, and detecting a temperature change due to the flow of the intake air An air flow rate detection device comprising: a third and a fourth temperature sensing member. 2. The apparatus according to claim 1, further comprising: flow direction determination means for determining whether the flow direction of the intake air is forward or reverse based on detection signals from the first and second thermosensitive bodies, and from the third and fourth thermosensitive bodies. And inflow air determination means for determining whether or not the flow of intake air is in a drift state, based on a detection signal of the intake air flow rate detection device. A detection operation stop means for temporarily stopping the detection operation of the intake air flow rate by the detection element when the flow direction determination means determines that the flow direction of the intake air is in the reverse direction. Suction air flow rate detection device. The reverse flow correction according to claim 2, wherein the flow rate correction value corrects a flow rate detection value of the intake air flow rate by the detection element on the basis of detection signals from the first and second thermosensitive bodies when determined by the flow direction detection means in the reverse direction. Air flow rate detection device comprising a means. The detection element according to claim 2, 3, or 4, wherein when the flow of intake air is determined to be in a drift state by the drift determination means, the detection element is applied to the detection element based on detection signals from the third and fourth thermosensitive bodies. And inflow air correction means for correcting the flow rate detection value by the air.