JP2018031636A - Air flow sensor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air flow sensor module capable of surely reducing and suppressing adhesion of dust or the like to an air flow sensor.SOLUTION: In a suction part 41 formed in an air flow sensor module provided with an air flow sensor 24, a suction port 63 into which air flows is provided so as to be positioned on a downstream side in a vertical direction with respect to the air flow sensor 24 disposed inside the suction part, and also, a bypass passage 61 is provided along an inflow direction where air inflows from the suction port 63, while a guide passage 62 communicating with the bypass passage 61 is provided in the vicinity of the suction port 63 of the bypass passage 61 so as to extend to the air flow sensor 24. Further, in the suction port 63, two magnets are oppositely provided so as to hold inflow air therebetween, and dust containing moisture is electrically charged to enable collection on a metal plate 65.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an airflow sensor module in which an airflow sensor is accommodated, and more particularly to an object that prevents adhesion of dust and the like to the airflow sensor and improves suppression.

  In operation control of an internal combustion engine mounted on a motor vehicle, since the amount of intake air is an important factor affecting the combustion state of fuel in the internal combustion engine, it is called a so-called airflow sensor that measures the intake amount. In general, a sensor is attached to an inlet portion of an intake pipe, and various airflow sensors have been proposed and put into practical use (see, for example, Patent Document 1).

Special table 2010-528303 gazette

  However, since the airflow sensor is exposed to an air flow that still contains a lot of dust, moisture, etc., dust and the like are more likely to adhere to the main part of the airflow sensor than other sensors on the downstream side. Therefore, there is a high possibility of causing a decrease in the air flow rate, deterioration of the sensor itself, and the like.

  The present invention has been made in view of the above circumstances, and provides an airflow sensor module capable of reliably reducing and suppressing adhesion of dust and the like to the airflow sensor.

In order to achieve the above object of the present invention, an airflow sensor module according to the present invention comprises:
An airflow sensor module comprising an air intake sensor in which an airflow sensor is disposed and a guide path through which air to be measured is guided to the airflow sensor is formed,
The intake portion has an intake port through which air flows, and the intake port is provided to be positioned downward in the vertical direction with respect to the airflow sensor disposed inside the intake portion.
A bypass passage communicating with the suction port is provided inside the intake portion, and the bypass passage is formed so that air flowing in from the suction port can be guided into the intake portion along a substantially horizontal direction. In addition, while a bypass hole that opens to the outside is drilled,
The guide path is formed so as to communicate with the bypass passage in the vicinity of the suction port of the bypass passage, and to extend to the airflow sensor positioned above the suction port in the vertical direction.
The suction port is provided with two magnets facing each other so as to sandwich the inflowing air.

  According to the present invention, it is possible to keep the intake air passing through the airflow sensor clean by charging and collecting the dust contained in the intake air, in particular, the dust containing moisture, and the dust airflow sensor. As a result, it is possible to reliably reduce and suppress adhesion to the sensor, and to improve the reliability and stability of the sensor.

It is a block diagram which shows the structural example of the exhaust-gas recirculation apparatus to which the airflow sensor module in embodiment of this invention is attached. It is a schematic diagram which shows typically the whole external appearance shape of the airflow sensor module in embodiment of this invention. It is a schematic diagram which shows typically the one outer surface part of the suction part of the airflow sensor module in embodiment of this invention. It is a schematic diagram which shows typically the other outer surface part of the suction part of the airflow sensor module in embodiment of this invention. It is the schematic diagram which showed typically the inside of the suction part of the airflow sensor module in embodiment of this invention in embodiment of this invention. It is a schematic diagram which shows typically schematic structure of the airflow sensor provided in the airflow sensor module in embodiment of this invention. It is explanatory drawing explaining the example of the temperature change with respect to the separation distance from the heater element which comprises the airflow sensor in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
FIG. 1 shows a configuration example of an exhaust gas recirculation device 101 mounted on a motor vehicle as a configuration example of a device to which an airflow sensor module 100 according to an embodiment of the present invention is attached. The configuration will be described with reference to FIG.

An intake pipe 12 for taking in air necessary for fuel combustion is connected to the intake manifold 14a of the engine 3, and an exhaust pipe 13 for exhausting exhaust gas is connected to the exhaust manifold 14b. .
A communication passage 15 that communicates the intake pipe 12 and the exhaust pipe 13 is provided at an appropriate position of the intake pipe 12 and the exhaust pipe 13. An EGR cooler 17 for cooling the gas and a communication state of the communication passage 15, in other words, an EGR valve 16 for adjusting the recirculation amount of the exhaust gas are sequentially arranged.

  Further, a known and well-known configuration in which the variable turbine 19 provided on the downstream side of the communication passage 15 in the exhaust pipe 13 and the compressor 20 provided on the upstream side of the communication passage 15 in the intake pipe 12 are main components. A variable turbo 18 is provided. Then, the compressor 20 is rotated by the rotational force obtained by the variable turbine 19, and the compressed air is sent to the intake manifold 14a as intake air.

Further, the intake pipe 12 is provided with an intercooler 21 for cooling the intake air at an appropriate position between the communication passage 15 and the variable turbo 18 described above.
An intake throttle valve 22 for adjusting the amount of intake air is provided between the intercooler 21 and the communication passage 15.

  A filter 23 for cleaning the intake air is provided on the upstream side of the intake pipe 12, and an airflow sensor 24 is provided on the downstream side for detecting the amount of intake air flowing in through the filter 23. Is provided. In the embodiment of the present invention, the airflow sensor 24 is provided so as to be able to detect the amount of intake air flowing through the intake pipe 12 in a state of being attached to an airflow sensor module 100 having a configuration described later.

  Further, in the intake pipe 12, an intake air temperature sensor 25 for detecting the temperature of intake air of the engine 3 is provided between the intercooler 21 and the intake throttle valve 22, and on the downstream side of the intake throttle valve 22. Is provided with an intake pressure sensor 26 for detecting the intake pressure of the intake manifold 14a.

On the other hand, in the exhaust pipe 13, an exhaust brake 28 (or an exhaust flap) that blocks the flow of exhaust gas is provided on the downstream side of the variable turbine 19, and a lambda sensor 27 is further provided on the downstream side of the exhaust brake 28.
The detection signals of the airflow sensor 24, the intake air temperature sensor 25, the intake air pressure sensor 26, and the lambda sensor 27 are input to an electronic control unit (not shown) so as to be used for fuel injection control processing and the like. It has become.

Next, the airflow sensor module 100 according to the embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the airflow sensor module 100 according to the embodiment of the present invention will be described with reference to FIG. 2. The airflow sensor module 100 includes a casing 31 and an airflow sensor disposed in the casing 31. 24 and a PCB substrate 32 on which an electronic circuit is mounted (see FIG. 2).

  The airflow sensor module 100 according to the embodiment of the present invention has a structure called a so-called plug-in type. That is, first, the casing 31 of the airflow sensor module 100 is entirely divided into an intake part 41, a circuit storage part 42, and a cable connection part 43, for example, using an insulating member such as a resin member. The external shape is an integral flat columnar shape.

In particular, the portion of the intake portion 41 can be inserted into a connection member (not shown) provided in the intake pipe 12 in order to connect the airflow sensor module 100. The intake portion 41 is fitted and fixed to the connecting member by insertion, and such a structure itself has a well-known configuration.
As described above, the airflow sensor module 100 is attached to the intake pipe 12 by a plug-in structure, and the amount of intake air passing through the intake pipe 12 can be detected by the airflow sensor 24 as will be described in detail later. ing.

Next, the airflow sensor 24 in the embodiment of the present invention will be described with reference to FIGS. 6 and 7.
The airflow sensor 24 according to the embodiment of the present invention is classified as a so-called hot wire type, but instead of a conventional heat wire (resistance wire), the whole is configured using a semiconductor member. Yes.

The airflow sensor 24 in the embodiment of the present invention has a base portion 51 formed in a roughly columnar shape using a semiconductor member, and two notches 52a and 52b are formed at the center portion thereof. It is formed at an appropriate interval in the longitudinal axis direction (left and right direction in FIG. 6) of the base portion 51.
A heater installation portion 53 is formed between the two notches 52a and 52b, and the heater installation portion 53 has a surface on the side of the notches 52a and 52b facing the bottom surfaces of the notches 52a and 52b, respectively. It is formed in a slope shape with an appropriate inclination.

A heater element 54 using a semiconductor member is formed on the top surface of the heater installation portion 53, and resistance elements 55a and 55b using a semiconductor member are formed in the notches 52a and 52b. , 56b is formed on the top surface.
The heater element 54 and the resistance elements 55a and 55b are positioned on the same plane so that the heater installation part 53 and the resistance element arrangement parts 56a and 56b have a height (the vertical direction in FIG. 6). Is set.

  The airflow sensor 24 is arranged so that the longitudinal axis of the base 51 (in the left-right direction in FIG. 6) follows the flow of intake air represented by the white arrow in FIG. 6, that is, in other words, By arranging the intake air to pass through one resistance element 55a, the heater element 54, and the other resistance element 55b in this order, the amount of intake air can be reduced due to the difference in resistance value between the two resistance elements 55a and 55b. It can be detected.

  FIG. 7 is an explanatory diagram for explaining the difference in temperature between the two resistance elements 55a and 55b. Hereinafter, the temperature difference generated in the two resistance elements 55a and 55b will be described with reference to FIG. .

  First, in FIG. 7, the horizontal axis represents the distance from the heater element 54, and the vertical axis represents the temperature. Also, in the figure, “END1” on the horizontal axis indicates one resistance element 55a side of two ends of the heater element 54 in the horizontal direction (left and right direction in FIG. 6), and “END2” The other resistance element 55b side is shown respectively.

  In FIG. 7, the solid line represents the temperature change according to the separation distance from the heater element 54 when the intake air is zero, and the temperature is the heater on either the resistance element 55a side or the resistance element 55b side. With the end portions END1 and END2 of the element 54 as starting points, the distance decreases from the heater element 54 with almost the same amount of change as the distance from the heater element 54 increases.

On the other hand, in FIG. 7, a dotted line represents a temperature change according to the separation distance from the heater element 54 when there is intake air, and on one resistance element 55a side (windward side), the heater element 54 It shows a change in which the temperature drops sharply only slightly away from one end END1, and the temperature change shows a change curve that protrudes downward with respect to the separation distance. It has become.
In FIG. 7, the point of the separation distance Ct1 from the end portion END1 is a point at which the temperature change with the separation distance from the end portion END1 becomes constant, and the point of the separation distance C1 from the end portion END1 is the end point. This is the midpoint of the point up to the separation distance Ct1 from the part END1, and the temperature at that point is T1.
In FIG. 7, C2 corresponds to C1, and Ct2 corresponds to Ct1. That is, the point of the separation distance C2 is an intermediate point from the end END2 to the point separated by the separation distance Ct2, and the point of the separation distance Ct2 is a point where the temperature change is constant.

  On the other hand, on the other resistance element 55b side (leeward side), the temperature change with respect to the separation distance in the range from the other end END2 of the heater element 54 to the separation distance C2 is in the range from the end END1 to the separation distance C1. It is more gradual than the temperature change. In addition, the temperature change with respect to the separation distance from the heater element 54 is reversed after the point separated from the end portion END2 by the separation distance C2.

That is, from the other end END2 of the heater element 54 to the point of the separation distance C2, the temperature change with respect to the separation distance shows a downward change curve, while the temperature with respect to the separation distance after the point of the separation distance C2 The change shows a change curve that is convex upward. The temperature at the point of the separation distance C2 from the end END2 is T2.
The above-described difference in temperature change between the two sides of the heater element 54 is expressed as, for example, the temperature difference ΔT = T2−T1 at the previous intermediate point, and the magnitude of this difference ΔT depends on the amount of intake air. It is known to be proportional.

Therefore, the intake air amount can be measured by detecting ΔT.
Actually, the change in the resistance value with respect to the temperature change in the two resistance elements 55a and 55b is converted into a voltage change by an electronic circuit (not shown) provided on the PCB substrate 32, thereby controlling the operation of the vehicle. It is supplied to an electronic control unit (not shown) to be performed.

Next, the structure and the like of the casing 31 to which the above-described airflow sensor 24 is attached will be described with reference to FIGS.
As outlined above, the casing 31 of the present invention is roughly divided into an air intake portion 41, a circuit storage portion 42, and a cable connection portion 43, and these members are made of an insulating member such as a resin. Are integrally molded, and the overall external shape is a generally flat columnar shape.

  In the airflow sensor module 100 according to the embodiment of the present invention, in the vertical direction, the cable connection portion 43 is positioned upward, and the intake portion 41 is on the intake pipe 12 (see FIG. 1) side. It is attached to the intake pipe 2 such that the longitudinal axis direction (the vertical direction in FIG. 2) substantially coincides with the vertical direction.

The intake portion 41 is provided with the airflow sensor 24 described above, and is provided with a bypass passage 61 and a guide passage 62 as will be described later, and serves as a place where intake air is measured by the airflow sensor 24. Yes.
The circuit storage part 42 is a part in which the PCB substrate 32 is stored and disposed.
The PCB substrate 32 includes a power supply circuit (not shown) for the heater element 54 of the airflow sensor 24, and a signal conversion circuit that converts a resistance value change of the two resistance elements 55a and 55b according to the intake air amount into a required voltage change. (Not shown) on which an electronic circuit is formed by a well-known so-called printed wiring technique or the like.

The cable connection unit 43 supplies the output signal of the electronic circuit mounted on the PCB substrate 32 to, for example, an electronic control unit (not shown) in which operation control of the automobile is executed. And a signal cable (not shown) for electrically connecting the electronic control unit (not shown).
A plurality of module-side connection terminals 71 that are connected to the PCB substrate 32 and output signals to the outside are disposed inside the cable connection portion 43. And a cable side connection terminal (not shown) made of a conductive member provided on a signal cable (not shown).

As will be described later, the air intake sensor 41 of the present invention is provided with an airflow sensor 24, a suction port 63 through which air flows, and a bypass passage 61 that guides the air that flows through the suction port 63 to the inside. A guide path 62 for guiding the air to be measured to the airflow sensor 24 is formed (see FIGS. 2 and 5).
The suction port 63 is lower in the vertical direction, in other words, in the longitudinal axis direction of the casing 31 (vertical direction in the drawing in FIG. 2) with respect to the airflow sensor 24 provided in the vicinity of the circuit housing portion 42 inside the suction portion 41. The opening is formed at a position in the direction, and the opening is formed in the casing 31 along the longitudinal axis direction.

Further, a bypass passage 61 communicating with the suction port 63 extends from the suction port 63 to the inside along a direction orthogonal to the longitudinal axis direction (up and down direction on the paper surface) of the casing 31. A bypass hole 64 that opens to the outside of the casing 31 is formed at the end of the bypass passage 61 provided with an appropriate length.
In addition, a flat metal plate 65 is attached to the bypass passage 61 in the vicinity of the bypass hole 64 on the passage surface. The metal plate 65 is for collecting charged dust (details will be described later).
The metal plate 65 is connected to a ground connection portion (not shown) provided in the vehicle via electric wiring (not shown), and is held at the ground potential.

In addition, a guide path 62 is formed inside the intake portion 41 so as to communicate with the bypass passage 61 in the vicinity of the suction port 63 and to extend to a portion where the airflow sensor 24 is disposed.
As will be described later, the guide path 62 changes the guide direction of the intake air by 180 degrees in a portion slightly extending in a direction opposite to the air flow sensor 24 from the portion where the air flow sensor 24 is provided, and the longitudinal direction of the casing 31. A bent portion 66 is formed by bending downward from the airflow sensor 24 along the axial direction (the vertical direction in FIG. 5), and the guide path 62 is turned 180 degrees and extends to an appropriate position. Thus, a termination portion 67 is provided. Further, the terminal portion 67 is provided with a main bypass hole 68 that opens to the outside of the casing 31, so that the intake air can be returned to the outside, that is, in the intake pipe 12 in the embodiment of the present invention. It can be done.

On the other hand, on one surface of the intake portion 41, that is, on the side where the bypass passage 61 and the guide path 62 are formed, a flat plate-like intake portion cover 69 is attached, and the bypass passage 61 and the guide path 62 are outside. It is not exposed (see FIG. 2).
In addition, in the vicinity of the suction port 63, a first magnet 70 a having a rectangular shape with an appropriate overall size is attached to the suction port lid 69 in the vicinity of the suction port 63 (see FIG. 3). .

A second magnet 70b having the same shape and size is attached to the outer surface of the casing 31 corresponding to the first magnet 70a described above with the suction port 63 interposed therebetween (see FIG. 4).
The first and second magnets 70a and 70b are magnetized in the thickness direction (the front and back direction in FIG. 3). For example, if the first magnet 70a is taken as an example, the front side in FIG. Assuming that the poles are magnetized, the opposite side, that is, the side of the surface joined to the outer surface of the casing 31, is an N pole.
In the embodiment of the present invention, the first magnet 70 a and the second magnet 70 b are arranged so that the magnetic poles on the surface side joined to the outer surface of the casing 31 are reversed.

That is, for example, if the magnetic pole on the surface side joined to the outer surface of the casing 31 of the first magnet 70 a is an N pole, the second magnet 70 b is on the surface side joined to the outer surface of the casing 31. The magnetic poles are provided to be S poles.
As a result, the lines of magnetic force generated between the first magnet 70a and the second magnet 70b are in the direction from the first magnet 70a to the second magnet 70b. In the embodiment of the present invention, it is assumed that the first and second magnets 70a and 70b are arranged so that the orientation of the magnetic poles is the same as in the above example for convenience of explanation.

Next, the flow of intake air and the operation of the first and second magnets 70a and 70b in the airflow sensor module 100 having the above-described configuration will be described below.
First, the intake air flowing through the intake pipe 12 flows into the intake port 63 (see FIG. 5).
Although the intake air has passed through the filter 23 (see FIG. 1), there is no dust, and usually a certain amount of dust is included.

Further, in the intake air that has passed through the filter 23, water droplets themselves and dust containing moisture also exist.
When the water droplet itself or dust containing water flows into the bypass passage 61 from the suction port 63, in the embodiment of the present invention, in FIG. Since they pass through at right angles, the water droplets themselves and the dust containing water will be charged positively by the principle of Fleming's right method and will travel through the bypass passage 61. In FIG. 5, the white circle represents the water droplet itself before charging or dust containing moisture, and the white circle marked with “+” represents the positively charged water droplet itself or moisture. The dust contained is represented respectively.
In FIG. 5, “×” in the white circle means that the direction of the magnetic field (lines of magnetic force) is from the front surface to the back surface.

  Since the water droplets contained in the intake air and the dust containing water are relatively heavy, the bypass passage 61 does not rise and flow into the guide passage 62 communicating with the bypass passage 61 in the vicinity of the suction port 63. , The metal plate 65 provided near the bypass hole 64 is attracted and attached to the metal plate 65.

As described above, the water droplets contained in the intake air flowing in from the suction port 63 and the dust containing water are charged positively, and most of them are collected by the metal plate 65, thereby guiding the water. The intake air containing almost no dust flows into the path 62 and travels along the guide path 62.
As described above, the airflow sensor 24 is disposed in the guide path 62, and the intake air passes through the airflow sensor 24 as indicated by the white arrow in FIG. It passes through the portion 66 and returns to the intake pipe 12 from the main bypass hole 68 ahead.

Thus, unlike the conventional case, the intake air passing through the airflow sensor 24 is clean and contains almost no dust, so that dust adheres to the airflow sensor 24 and hinders the operation of the airflow sensor 24. Is reliably suppressed and prevented, and a highly reliable and stable detection signal is provided.
In the above-described embodiment of the present invention, the first and second magnets 70a and 70b are disposed on the left and right of the suction port 63 when the suction port 63 is viewed from the air inflow direction. The arrangement position need not be limited to this, and may be arranged so as to face each other above and below the suction port 63, for example.
Furthermore, the arrangement of the magnetic poles of the first and second magnets 70a and 70b across the suction port 63 is not necessarily limited to the arrangement described with reference to FIGS. It is good also as arrangement of.

  The present invention can be applied to an airflow sensor that is desired to reliably reduce and suppress the adhesion of dust and the like.

24 ... Airflow sensor 61 ... Bypass passage 65 ... Metal plate 70a ... First magnet 70b ... Second magnet 100 ... Airflow sensor module

Claims (3)

An airflow sensor module comprising an air intake sensor in which an airflow sensor is disposed and a guide path through which air to be measured is guided to the airflow sensor is formed,
The intake portion has an intake port through which air flows, and the intake port is provided to be positioned downward in the vertical direction with respect to the airflow sensor disposed inside the intake portion.
A bypass passage communicating with the suction port is provided inside the intake portion, and the bypass passage is formed so that air flowing in from the suction port can be guided into the intake portion along a substantially horizontal direction. In addition, while a bypass hole that opens to the outside is drilled,
The guide path is formed so as to communicate with the bypass passage in the vicinity of the suction port of the bypass passage, and to extend to the airflow sensor positioned above the suction port in the vertical direction.
An airflow sensor module, wherein two magnets are provided opposite to each other so as to sandwich inflowing air. The air to be measured is intake air in an intake pipe of an automobile,
The said intake part has a plug-in structure which can be inserted in the connection part provided in the said intake pipe, and is fitted with the said connection part by the said insertion. Airflow sensor module.   The airflow sensor includes resistance elements provided on both sides of the heater element, and the one resistance element, the heater element, and the other resistance element are provided along the guide path. The airflow sensor module according to claim 2, wherein the airflow sensor module is disposed so as to be positioned.

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