JP2001108500A - Heat generation resistance-type flow rate-measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat generation resistance-type flow rate-measuring device that properly detects the flow rate of a fluid where a forward flow and a backward coexist like a pulsation flow accompanied with a backward flow. SOLUTION: A sub passage 3 that has at least two heat generation resistors 1 being installed near upstream and downstream sides in the inside is composed of a first channel 302 that has a bending part 303, and a second channel 309 in which forward flow hard to flow and to introduce backward flow to the sub passage 3 when the backward flow is generated in a main passage 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistance type flow rate measuring device for judging a flow direction of a fluid in a fluid passage when the fluid has a flow changing in a forward direction and a reverse direction and outputting a signal corresponding to the flow direction. The present invention relates to an apparatus, and more particularly to a heating resistance type flow rate measuring apparatus suitable for measuring an intake air flow rate of an internal combustion engine.

[0002]

2. Description of the Related Art A conventional apparatus is disclosed in, for example,
There is a hot wire air flow meter described in Japanese Patent Publication No. 812. In this known example, the element structure of the heating resistor for detecting the forward and reverse flows, the direction discrimination, the output circuit configuration of the flow signal, and the detection mechanism are specifically described. There is no description about the passage configuration that provides a heating resistor in the sub-passage with the section and guides the backflow to the heating resistor, and the passage configuration that can clearly measure the backflow is to connect the detection element in the main passage with the sub-passage. The one installed without the installation and the one installed in a simple circular conduit are described.

In order to accurately detect the flow rate over the entire range from a steady flow to a pulsating flow accompanied by a reverse flow, such as the intake air of an internal combustion engine, first, the plus error of the flow measuring device when the reverse flow occurs is determined. In order to reduce the flow rate, it is necessary to perform flow rate detection by subtracting the reverse flow rate from the forward flow rate. The technique described in the above-mentioned publication is capable of outputting both forward and reverse flow rate signals, and consideration has been given to reducing this error.

[0004]

The above-mentioned prior art heating resistance type flow rate measuring device having a sub-passage having a bent portion does not cause a backflow in the sub-passage even if a backflow occurs in the main passage. It is difficult to measure the backflow accurately.In addition, when the measuring element is installed in the main passage without providing the sub passage or in the simple circular pipe, the output signal will be Had a problem that a negative error was shown.
This negative error is due to the non-linearity of the heat radiation characteristic of the heating resistor and the response delay, and is caused by the pulsation of the forward flow, so that it cannot be solved by measuring the reverse flow rate. Met.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heating resistance type flow rate measuring device capable of properly detecting the flow rate of a fluid in which forward and reverse flows are mixed, such as a pulsating flow accompanied by a backward flow. It is in.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to dispose at least two heating resistors in a sub-passage provided in an intake passage of an internal combustion engine close to an upstream side and a downstream side. While determining whether the air flow direction is the forward direction or the reverse direction from the difference in the amount of heat radiation of the downstream heating element,
In a heating resistance type flow rate measuring device that outputs a signal corresponding to a flow rate in a forward direction and a reverse direction, the sub-passage has at least one bent portion and a first flow path including the heating resistor inside, This is achieved by including a second flow passage that takes in the backflow into the first flow passage when the backflow occurs in the intake passage.

[0007]

According to the construction of the present invention, a heating resistor for detecting the flow rate is provided in the sub-passage so that the flow in the forward direction flowing into the sub-passage has a higher inertia effect than the flow in the main passage when pulsating. The length of the passage for the forward flow in the passage is made longer than the length of the same portion of the main passage, thereby canceling the negative error. A flow path for guiding the flow in the direction is provided.

In other words, the heating resistance type flow rate measuring device for determining the flow direction of the forward direction and the reverse direction and measuring the flow rate is a known technique as described above, but maintains its operation and effect. However, a technique for avoiding a negative measurement error due to a pulsating flow is not disclosed, and the present invention implements a countermeasure.

More specifically, the output with respect to the flow rate of the heat-generating resistor type flow rate measuring device exhibits a non-linear characteristic due to the physical phenomenon of heat radiation from the heat-generating resistor to the fluid. For this reason, when measuring the pulsating flow, a negative error occurs in the measured value due to heat radiation characteristics or detection delay by the control circuit. Therefore, a sub-passage structure is used in which the measured value is raised by the pulsating flow so as to cancel the negative error caused by the pulsating flow. That is, if the heating resistor for detecting the flow rate is arranged in the sub-passage and the total length of the sub-passage is formed longer than the length of the main passage of the same portion, the pulsation flow in the sub-passage is smaller than the pulsation flow generated in the main passage. It has a larger inertia effect than the main passage. For this reason, since the average flow velocity of the pulsating flow in the sub passage is increased, a positive error can be caused in the measured value, and the measured value can be offset from the above-described negative error.

[0010] However, the above-mentioned sub-passage which causes the plus error has a configuration in which the flow in the reverse direction cannot be sufficiently guided to the heating resistor. For this reason, the second which introduces backflow into the sub-passage
Are provided, and when a backflow occurs in the main passage, the backflow is guided to the sub-passage. For example, by having a bent portion, a first heat-generating resistor provided inside is provided.
Is a sub-passage which is longer than the length of the main passage and has a large inertia effect. The second flow path communicating with the first flow path downstream of the heating resistor in the first flow path has an outlet opening on a surface perpendicular to the back flow generated in the main passage, and To the first flow path, that is, the flow path leading to the sub-passage.

Here, when a pulsating flow having no backflow occurs in the main passage, the flow in the sub-passage mainly flows through the first passage, and when the backflow occurs, the backflow is reduced by the second passage. Is necessary to obtain a sufficient effect.

On the other hand, the reason why the inlet opening surface of the first flow passage is formed in a cross section substantially perpendicular to the main flow of the intake passage and the outlet opening surface is formed substantially parallel to the main flow is as follows. When a forward flow flows through the passage, a dynamic pressure is generated at the inlet of the first flow passage to increase the pressure, and the outlet is formed as a merging surface perpendicular to the main flow to reduce the pressure. The pressure difference between the outlets is increased to facilitate the flow of the fluid flowing through the first flow path.

[0013] Further, the reason why the inlet opening surface of the second flow path for the backflow when the backflow occurs in the intake passage is formed in a cross section substantially perpendicular to the main flow direction of the backflow is as follows.
Even if the flow resistance of the flow path is relatively large,
A dynamic pressure is generated at the inlet of the flow path, thereby facilitating the backflow to the sub-passage.

[0014] Further, a branch (merging portion) between the first flow path and the second flow path is formed substantially at right angles to each other, and the ventilation from the branch to the outlet of each flow path is formed. The reason why the resistance of the second flow path is larger than that of the first flow path is that it is difficult for the forward flow to flow toward the second flow path when flowing through the first flow path. To do that.

Furthermore, the reason why the ventilation resistance of the second flow path is smaller than that of the forward flow in the case of the backward flow is that the larger the ventilation resistance of the second flow path is, the more the forward flow is reduced. Although it becomes difficult to flow through the second flow path and the negative error for flowing through the first flow path is reduced, if it is too large, the introduction amount of the flow in the reverse direction is reduced, and the determination of the flow direction and the detection of the flow rate in the reverse direction are difficult. On the contrary, it is intended to reduce the ventilation resistance against the backflow and to facilitate the backflow.

Also, the reason why the outlet opening of the second flow passage into which the backflow flows into the first flow passage is formed so as to be shifted to a position not overlapping with the heating resistor in the flow direction of the backflow is as follows. When the frequency of the pulsating flow accompanied by backflow is different, or when backflow occurs in a wide frequency band, the amount of backflow in the high-frequency range is reduced to the heating resistor part, and the backflow in the high-frequency range is reduced. This is to prevent the detection amount from becoming too large.

Furthermore, the reason why the second flow path is constituted by a plurality of flow paths is that the length of each flow path is different and a time difference (change) occurs in the introduction of the back flow, and the amount of detected back flow in each frequency range is reduced. This is because it can be performed properly.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 is a cross-sectional view showing an exothermic resistance type flow rate measuring apparatus according to an embodiment of the present invention. FIG. 2 is an external view as viewed from the left side (upstream side) of FIG.

An electronic circuit 8 and a housing 9 are fixed on the upper surface of the base member 7, and a connector 11 for electrically connecting to an external device is integrated with the housing 9, and the upper surface of the housing 9 is covered by a cover 10. Have been done. A heat-generating resistor 1 for detecting a flow rate and discriminating a flow direction, and a temperature-sensitive resistor 2 for detecting a body temperature are electrically connected to an electronic circuit 8 and fixed to a holder 19. ing.

The heating resistor 1 has at least two temperature-sensitive resistors formed on the surface of a plate-like substrate on the upstream and downstream sides. The sub-passage 3 is formed by an inlet opening 301 opening in a plane perpendicular to the base member 7, a passage parallel to the base member and a passage perpendicular to the base member from the inlet opening 301, and bent at a right angle. It comprises a first flow path 302 having a portion 303 and an outlet opening surface 305 that opens in a plane parallel to the base member 7. In other words, the sub passage 3 is an L-shaped passage, and the inlet opening surface 3 formed in a plane perpendicular to the main flow direction of the air flowing through the main passage 5 as a ventilation passage.
01, a first flow path 302 having a bent portion 303 bent at a right angle, and an outlet opening surface 305 formed in a plane parallel to the main flow direction of the main passage 5.

The heating resistor 1 of the bent portion 303
Immediately downstream of the sensing portion, a second flow path 309 for introducing a flow in the opposite direction parallel to the base member is formed. Further, the sub-passage constituting member 4 is fixed to the base member 7 so that the heating resistor 1 is located in the first flow path 302.

On the other hand, the flow meter body 6 constituting the main passage 5
An insertion hole 14 for inserting the sub-passage constituting member 4 and an attachment fixing surface 15 for attaching the base member 7 are provided on the wall surface of the first embodiment. In the flow meter body 6, the first
The sub-passage constituting member 4 is inserted into the main passage 5 from the insertion hole 14 so that the flow path 302 of the main passage 5 is parallel to the forward flow direction 17 of the main passage 5, and is mounted so that the periphery of the insertion hole 14 is sealed. The base member 7 is fixed to the outer wall of the main passage by screws 18 with a rubber packing 16 interposed between the fixing surface 15 and the bottom surface of the base member 7.

FIG. 3 is a cross-sectional view showing a heating resistance type flow rate measuring apparatus according to another embodiment of the present invention. As compared with the above embodiment, this embodiment is an embodiment in which a configuration for further improving the accuracy and a method of fixing the sub-passage constituent member and the base member are embodied. FIG. 4 is an external view as viewed from the left side (upstream side) of FIG. FIG. 5 is a partially enlarged view of the first flow path and the second flow path in FIG. The description will be made with reference to FIGS.

The terminal 13 is integrated with the holder 19 so that the terminal 13 passes through the inside of the holder 19, and the base member 7 and the holder 19 are fixed through the hole of the base member 7. The electronic circuit 8 is fixed to the upper surface of the base member 7 or the holder 19 and is electrically connected to the terminal 13 via a conductive member 22 such as a wire. The housing 9 is also fixed to the upper surface of the base member 7, and the upper surface of the housing 9 is covered by fixing the cover 10.

On the other hand, at the end opposite to the electronic circuit 8 of the terminal 13, two heat generating resistors 1 and two temperature sensitive resistors 2 are arranged so as to overlap upstream and downstream, respectively, and are electrically connected and fixed. Is done. In this embodiment, the two temperature-sensitive resistors 2 are fixed so as to be located near the inner corner inside the right-angled bent portion 303 of the sub-passage 3, and the two heating resistors 1 are connected to the sub-passage 3
The first flow path 302 is fixed so as to be close to a position closer to the base member 7 than the temperature-sensitive resistor 2 and to be upstream and downstream.

The sub-passage constituting member 4 forms an inlet opening 301 formed in a plane perpendicular to the main flow direction of the main passage 5, a first flow path 302 having a bent portion 303, and a direction parallel to the main flow direction of the main passage 5. A nozzle-shaped second flow path 309 is formed in the L-shaped sub-passage 3 composed of the outlet opening surface 305 formed on the surface, and the nozzle-shaped second flow path 309 expands with respect to the flow in the forward direction. The nozzle-shaped second flow path 309 is provided in a shape protruding in the direction of the heating resistor 1,
As shown in the figure, the outlet opening 320 of the second flow path 309 located in the flow path 302 is shifted to a position where it does not overlap the heating resistor 1 in the flow direction of the backflow. In other words, the disposition position of the heating resistor 1 is at a position deviated from an extension in the mainstream direction of the backflow. Note that the temperature-sensitive resistor 2 may be located at a position deviated from the mainstream direction of the backflow.

The reason why the second flow path 309 is formed in a nozzle shape as described above is to increase the ventilation resistance when the forward flow flows through the second flow path as compared with the case of the reverse flow, in other words. This is because the flow in the forward direction is difficult to flow and the flow in the reverse direction is easy to flow, and the correction of the minus error is appropriately performed to improve the measurement accuracy. Further, the reason for shifting to a position that does not overlap with the heating resistor 1 is to avoid an influence on the heating resistor 1 due to a backflow generated in a high frequency range and to prevent a measurement error in a high frequency range from increasing. .

When the backflow occurs in the main passage 5, the inlet opening surface 323 of the second flow passage for the backflow is formed substantially perpendicular to the main flow direction of the backflow. In this way, even if the ventilation resistance of the second flow path 309 is relatively large,
The backflow generates a dynamic pressure at the inlet of the second flow path 309 to facilitate guiding the backflow to the sub-passage 3.

Furthermore, a tray-shaped inlet 30 dug leaving a wall around the periphery provided for the purpose of guiding air taken into the sub-passage 3 over a wide range, particularly from the vicinity of the center of the main passage 5.
6. An inclined surface 307 having walls on both sides provided by stabilizing the flow at the outlet portion, and the tip of the inclined surface is connected to the outlet opening surface 30.
Exit eaves 308 and the holder 1 which were made to travel below 5
9 between the hole 401 for inserting the hole 9 and the holder 19
Are formed in the sub-passage constituting member 4.

As shown in FIG. 5, the arrangement position 322 of the heating resistor 1 is higher than the center line of the first flow path 302 parallel to the main flow direction of the main flow path 5 by the holder 19 (the base member 7). )
The center line 321 of the second flow path 309 is disposed substantially on the same line as the center line of the first flow path 302 described above. Therefore, the second flow path 30 flows in from the inlet opening surface 323 of the second flow path and corresponds to the outlet.
The reverse flow having the center line 321 of the second flow path, which is discharged from the 9 outlet openings 320, is formed shifted from the arrangement position 322 of the heating resistor 1. That is, the first
The outlet opening for the reverse flow of the second flow path formed in the second flow path is formed to be shifted to a position that does not overlap the heating resistor in the flow direction of the reverse flow.

In addition, a digging hole 403 is provided between the bottom surface of the tray-shaped inlet 306 and the inner wall of the first flow path 302 to make the sub-passage constituting member 4 uniform in thickness and to prevent a change in shape due to sink in plastic molding. While reducing material costs and weight.

The sub-passage constituting member 4 has a holder insertion hole 4
01 and the holder 1 at the joint surface 402.
9 and fixed. Here, a groove 404 is formed by the step provided on the holder 19 and the joint surface 402 of the sub-passage constituting member 4. The groove 404 is a mounting groove for the O-ring 20, and the O-ring 20 seals the insertion hole 14 on the wall of the main passage. As described above, a module in which the circuit portion, the sub-passage portion, and the O-ring for insertion hole sealing are integrated is configured.

By fixing this to the flow meter body 6 in the same manner as in the above-described embodiment, a heating resistance type flow measuring device is completed. In this embodiment, since the O-ring for sealing the insertion hole is mounted on the module, no rubber packing is required. In this embodiment, the housing 9 is fixed together with the base member 7 with screws 18 to increase the fixing strength of the housing. Further, a rectifying grid 21 is provided on the inlet surface of the main passage 5 of the flowmeter body 6. The figure shows that the measurement accuracy has been further improved by mounting.

FIG. 6 is a cross-sectional view showing another embodiment of the heating resistance type flow rate measuring apparatus according to the present invention. FIG. 7 shows FIG.
FIG. 3 is an external view of the left side (upstream side) of FIG.

FIG. 8 is a sectional view taken along the line AA of FIG.

In this embodiment, the auxiliary passage 3 and the main passage 5 are formed integrally with the flow meter body 6. The sub-passage 3 is composed of an L-shaped first flow path 302 and a second flow path 309 for introducing a flow in the opposite direction, as in the above-described embodiment. The sub passage 3 is formed integrally with the flowmeter body 6.
Is formed in a shape in which the first flow path is bridged in the diameter direction of the main passage 5 in a groove shape (a shape in which the downstream side is open), and the back plate 310 that blocks the downstream side of the first flow path is fixed to the sub flow path. Passage 3 is completed.

Accordingly, the second flow path 309 is formed integrally with the back plate 310 downstream of the bent portion 303 of the first flow path, in a direction perpendicular to the first flow path 302, and formed in the first flow path. The outlet openings 305 are provided on both sides of the first flow path. Eaves-like projections 308 are formed on both sides upstream of the outlet opening surface 305, so that the inlet opening 3 of the first flow path is formed.
Reference numeral 01 denotes a shape in which the bottom of the saucer 500 is inclined.

Similarly, the opening surface of the second flow passage is formed in a saucer shape 500 having an inclined bottom surface. The heating resistor 1 of the present embodiment is formed by forming film-shaped temperature-sensitive resistors on the upstream surface and the downstream surface of a cylindrical bobbin, and can detect the flow in the forward direction and the reverse direction. It is electrically connected to the circuit 8. Therefore, by inserting the holder 19 into the insertion hole of the flowmeter body 6 and fixing the housing 9 to the flowmeter body 6 so that the heating resistor 1 is positioned inside the sub-passage 3, the heating resistance type flowmeter can be used. Be completed.

FIG. 9 is a cross sectional view showing another embodiment of the heating resistance type flow rate measuring apparatus according to the present invention. In the present embodiment, the second flow path 309 is composed of a plurality of flow paths. Then, a housing 9 and an auxiliary passage 3 for protecting the interior of the electronic circuit 8 are integrally formed, and inserted through a hole 14 provided in a wall surface of the intake passage so that most of the auxiliary passage 3 and the housing 9 are located in the main passage 5. This shows an embodiment of a heating resistance type flow rate measuring device in which the connector 11 is fixed outside the intake passage.

An electronic circuit 8 and a housing 9 are fixed on the upper surface of the base member 7, and a connector 11 for electrically connecting to an external device is integrated with the housing 9, and the upper surface of the housing 9 is covered by a cover 10. Have been done. The heating resistor 1 for flow rate detection and flow direction discrimination and the temperature-sensitive resistor 2 for fluid temperature detection are integrally formed on a plate-like base and are electrically connected to the electronic circuit 8. After being fixed, it is fixed to the housing 9 or directly fixed to the housing 9. The L-shaped sub-passage 3 has a first flow path 302 and a second flow path 2 for introducing a reverse flow.
The second flow passages 309a and 309b are formed. The heating resistor 1 is arranged upstream of the bent portion 303, and the two second flow paths 309a and 309b are branched on the upstream side and the downstream side of the heating resistor 1. here,
Second branching on the upstream side with respect to the forward flow of the heating resistor 1
Flow path 309a is the second flow path 3 branched on the downstream side.
The flow path has a bent portion so as to have a flow path length considerably longer than that of the flow path 09b. Then, the second flow path 30
9b is a very short hole-shaped channel provided on the wall surface of the first channel 302.

When a plurality of (two) second flow paths 309a and 309b having different lengths are provided on the upstream side and the downstream side of the heating resistor 1, when a backflow occurs in the main passage 5, The backflow guided from the second flow path 309b on the downstream side to the first flow path 302 has a slight time difference so that it is canceled by the backflow guided to the second flow path 309a on the upstream side. Works. Therefore, the reverse flow rate flowing through a predetermined portion of the heating resistor 1 can be limited so as to be different depending on the frequency of the pulsating flow, and excessive detection of the reverse flow rate in a high frequency range can be prevented.

FIG. 10 is a diagram showing a control system for an internal combustion engine using the heat generation resistance type flow rate measuring device according to the present invention. FIG. 2 is a diagram showing an embodiment of a control system for controlling an internal combustion engine of an electronic fuel injection system.

The intake air 101 sucked from the air cleaner 100 is supplied to the body 102 of the heating resistance type flow rate measuring device.
Manifold 1 including intake duct 103, throttle body 104, and injector 105 to which fuel is supplied
After passing through 06, it is sucked into the engine cylinder 107. On the other hand, gas 108 generated in the engine cylinder is discharged through an exhaust manifold 109.

The air flow signal output from the circuit module 110, the throttle valve opening signal output from the throttle angle sensor 111, and the oxygen concentration meter 1 provided in the exhaust manifold 109 of the heating resistance type flow measuring device.
The control unit 114, which inputs the oxygen concentration signal output from the engine 12 and the rotation speed signal output from the engine tachometer 113, calculates these signals to obtain an optimum fuel injection amount and an idle air control valve opening. The injector 105 and the idle air control valve 115 are controlled based on the values.

Here, if the intake air flows from the air cleaner 100 toward the engine cylinder 107 as described above, the heating resistance type flow rate measuring device having the function of detecting the reverse flow as in the present invention is unnecessary. However, when the opening of the throttle valve 116 is large, the air taken into the engine cylinder 107 is not constant in time, but is intermittent, so that the intake air becomes a pulsating flow, and particularly, the pulsation cycle of the intake air, In other words, due to the resonance between the engine speed and the natural frequency of the intake system, the amplitude of the pulsating flow becomes extremely large, and the amplitude of the pulsating flow increases with the flow in the opposite direction. That is, since a flow that causes a reverse flow is generated only at a specific engine speed, in order to accurately measure the flow rate of the air taken into the engine cylinder 107 under all engine operating conditions, it is necessary to use the forward direction as in the present invention. There is a need for a heating resistance type flow measurement device capable of detecting a reverse flow rate and accurately measuring a steady flow to a pulsating flow accompanied by a reverse flow.

[0047]

The effects of the present invention will be described based on the measurement of the intake air flow rate of the internal combustion engine.

FIG. 11 is a graph in which the vertical axis represents the air flow rate measured by the conventional heating resistance type flow rate measuring apparatus which does not detect the reverse flow rate, and the horizontal axis represents the pressure downstream of the throttle valve.
It shows the result of measurement using the engine speed as a parameter. FIG. 12 shows the results of the same measurement using the embodiment shown in FIGS. 3 to 5 of the present invention. In the conventional product shown in FIG. 11, the air flow actually sucked into the engine cylinder should be substantially linear as shown by the dotted line, but a minus error due to the pulsating flow and a large plus error due to the reverse flow occur, and as shown by the solid line. become.

On the other hand, in the developed product shown in FIG. 12, the minus error generated in the conventional product is almost eliminated, and the plus error due to the backflow can be reduced to about 1/10 in the entire rotation speed range.

Therefore, the flow rate of the fluid that changes from a steady flow to a pulsating flow and a pulsating flow accompanied by a reverse flow can be discriminated in the forward and reverse directions, and a high-precision heating resistance type that outputs a signal corresponding to the flow rate. There is an effect of providing a flow measurement device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a heating resistance type flow rate measuring device according to an embodiment of the present invention.

FIG. 2 is an external view as viewed from the left side (upstream side) of FIG.

FIG. 3 is a cross-sectional view showing a heating resistance type flow rate measuring device according to another embodiment of the present invention.

FIG. 4 is an external view as viewed from the left side (upstream side) of FIG. 3;

5 is a partially enlarged view of a first flow path and a second flow path in FIG.

FIG. 6 is a cross-sectional view showing a heating resistance type flow rate measuring device according to another embodiment of the present invention.

FIG. 7 is an external view as viewed from the left side (upstream side) of FIG. 6;

FIG. 8 is a sectional view taken along the line AA of FIG. 6;

FIG. 9 is a cross-sectional view showing a heating resistance type flow rate measuring apparatus according to another embodiment of the present invention.

FIG. 10 is a diagram showing a control system for an internal combustion engine using the heat-generating resistance type flow rate measuring device according to the present invention.

FIG. 11 is a diagram showing a measurement result of an intake air flow rate of an internal combustion engine by a conventional flow rate measurement device.

FIG. 12 is a diagram showing a measurement result of an intake air flow rate of an internal combustion engine by the flow rate measurement device of the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating resistor, 2 ... Temperature sensing resistor, 3 ... Sub passage, 4 ... Sub passage constituent member, 5 ... Main passage, 6 ... Flow meter body, 7 ... Base member, 8 ... Electronic circuit, 9 ... Housing, DESCRIPTION OF SYMBOLS 10 ... Cover, 11 ... Connector, 13 ... Terminal, 14 ... Insertion hole, 15 ... Mounting fixed surface, 16 ... Rubber packing, 17 ... Forward flow direction, 18 ... Screw, 19 ... Holder, 20 ... O-ring, 21 ... Rectifying grid, 22: conductive member, 100: air cleaner, 101: intake air, 102: heating resistance flow rate measuring device, 103: intake duct, 104: throttle body, 105: injector, 106: manifold, 107: engine cylinder, 108 ... gas, 109
... Exhaust manifold, 110 ... Circuit module, 111
... Throttle angle sensor, 112 ... Oxygen concentration meter, 113
... tachometer, 114 ... control unit, 115
... Idle air control valve, 116 ... Throttle valve, 301 ... Inlet opening surface, 302 ... First flow path,
303: bent portion, 305: outlet opening surface, 306: saucer-shaped entrance, 307: inclined surface, 308: exit eaves, 309, 3
09a, 309b: second flow path, 310: back plate, 320: outlet opening, 321: center line of the second flow path, 322: arrangement position of heating resistor, 323: second position of the second flow path Inlet opening surface, 401: holder insertion hole, 402: joining surface, 403: meat hole, 404: groove, 500: saucer shape

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Chihiro Kobayashi 2520 Oji Takaba, Hitachinaka City, Ibaraki Prefecture Inside the Hitachi, Ltd.Automotive Equipment Division (72) Inventor Yasunori Mohri Hitachi, Ltd. Automotive Equipment Division (72) Inventor Hitoshi Ishikawa 2477, Kashima-Yatsu, Oaza Takaba, Hitachinaka-shi, Ibaraki Prefecture Within Hitachi Automotive Engineering Co., Ltd. Address Co., Ltd.Automotive Equipment Division, Hitachi, Ltd.

Claims (9)

[Claims] An at least two heating resistor is provided in an auxiliary passage provided in an intake passage of an internal combustion engine in the vicinity of an upstream side and a downstream side, and the heating resistor of the upstream side and the downstream side is connected to each other. In the heating resistance type flow rate measuring device, which determines whether the air flow direction is forward or reverse from the difference in the amount of heat released, and outputs a signal corresponding to the flow rate in the forward direction and the reverse direction, the sub-passage A first flow path having at least one bent portion and including the heating resistor therein, and a second flow path for taking the reverse flow into the first flow path when the reverse flow occurs in the intake passage. A heating resistance type flow rate measuring device characterized by including a path. 2. An opening opening surface of the first flow passage according to claim 1, wherein an inlet opening surface of the first flow passage is formed substantially perpendicular to a main flow direction of air flowing through the intake passage. Is a heating resistance type flow rate measuring device characterized by being formed substantially parallel to the main flow direction. 3. The backflow according to claim 1, wherein an inlet opening surface of the second flow passage against the backflow when the backflow occurs in the intake passage is substantially perpendicular to a main flow direction of the backflow. An exothermic resistance type flow rate measuring device characterized by being formed. 4. The branch according to claim 1, wherein the first flow path and the second flow path are separated from each other.
The (converging section) is formed at a substantially right angle to each other. 5. The airflow resistance according to claim 1, wherein a flow resistance from a branch (joining portion) of the first flow path and the second flow path to an outlet of each flow path. Wherein the second flow path is larger than the first flow path. 6. The airflow resistance of the second flow passage according to any one of claims 1 to 5, wherein the airflow resistance to the backflow when the backflow occurs in the intake passage is a more forward flow. An exothermic resistance type flow rate measuring device characterized in that it has a shape smaller than the time. 7. The back flow outlet of the second flow passage formed in the first flow passage according to any one of claims 1 to 6, wherein the outlet opening for the back flow of the second flow passage is formed in a direction of the back flow. A heating resistance type flow rate measuring device, wherein the heating resistance type flow measuring device is formed so as to be shifted to a position not overlapping with the heating resistor. 8. The heating resistance type flow measurement device according to claim 1, wherein the second flow path is constituted by a plurality of flow paths. 9. A control system for an internal combustion engine, wherein the control of the internal combustion engine is performed by using the heating resistance type flow rate measuring device according to any one of claims 1 to 8.