JP3895948B2 - Flow sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flow sensor for measuring the flow rate or flow velocity of a fluid flowing in a flow path, and more particularly to a thermal flow sensor.
[0002]
[Prior art]
Various thermal flow sensors for measuring the flow rate and flow velocity of various fluids have been proposed in the past (eg, Japanese Patent Application Laid-Open No. 4-295724, Japanese Patent Publication No. 6-25684, and Japanese Patent Application Laid-Open No. 8-146026). etc). This type of flow sensor is used by installing a flow velocity detection element having a temperature detection means so as to be parallel to the flow of the fluid to be measured in the pipe.
[0003]
8 and 9 show a conventional flow sensor used for measuring a flow rate of gas (air) flowing in an intake pipe of an automobile engine. In these drawings, 1 is an intake pipe provided with an air filter 2, 3 is a bypass flow path provided in the middle of the intake pipe 1, and 4 is a flow sensor incorporated in the bypass flow path 3.
[0004]
The flow sensor 4 includes a flow rate detection element 5, a mounting plate 6, a wiring board 7, and the like incorporated in the bypass flow path 3. The flow rate detecting element 5 includes a silicon substrate 10 having a diaphragm 9, a heating element (resistive heater) constituting temperature detecting means 11 formed on the diaphragm 9, two temperature sensors, and an ambient temperature formed on the silicon substrate 10. It consists of sensors. A part of the wiring metal thin film 12 of the temperature detecting means 11 is led out of the intake pipe 1 together with the silicon substrate 10 and the wiring substrate 7, and the electrode metal pad A is formed on the wiring substrate 7. The electrode pad B is electrically connected by a bonding wire 13 and the part is sealed with resin. Note that portions other than the electrode pads A on the surface of the silicon substrate 10 are covered with an insulating protective film.
[0005]
In the flow sensor 4 having such a structure, when a part of the air 15 sucked into the intake pipe 1 through the air filter 2 is diverted and passes through the bypass passage 3, the temperature detecting means 2 is formed. A temperature difference is generated between the two temperature sensors, the voltage difference or resistance value difference is detected by a bridge circuit, and the flow rate or flow rate of the air 15 can be detected by calculating with a calculation circuit (not shown).
[0006]
[Problems to be solved by the invention]
In the conventional flow sensor 4 described above, when the electrode pad A of the wiring metal thin film 12 of the flow velocity detection element 5 and the electrode pad B of the wiring metal thin film of the wiring substrate 7 are connected by the bonding wire 13 or the like in the bypass passage 3. Since moisture and fine organic substances contained in the air 15 as the fluid to be measured adhere and corrode, the connection is made outside the intake pipe 1. However, in the structure in which the electrical connection between the flow velocity detection element 5 and the wiring substrate 7 is performed outside the intake pipe 1, the silicon substrate 10 needs to protrude outside the intake pipe 1, so the flow velocity detection element 5 itself However, there is a problem that the number of sensors that can be taken from one wafer is reduced and the cost is increased. Further, if the shape and size of the bypass passage 3 change, it is necessary to redesign the size of the flow velocity detecting element 5 and change the size of the silicon substrate 10 accordingly.
[0007]
Therefore, as one of the structures for reducing the size of the flow velocity detecting element 5, it is conceivable to electrically connect the electrode pads A and B in the bypass passage 3 and to seal the connection portion with resin. However, in such a structure, since the resin-sealed portion protrudes from the surface of the flow velocity detecting element 5, this disturbs the flow of the air 15 or generates vortices (if the vortex is generated, measurement accuracy is not preferable). Decreases).
[0008]
The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to reliably protect the electrical connection between the flow velocity detection element and the wiring board from the fluid to be measured. In addition to improving the measurement accuracy by reducing the size, durability, reliability, etc. of the flow velocity detection element, and improving the measurement accuracy by rectifying the fluid so that turbulent flow and vortices do not occur, the common design of the flow velocity detection element An object of the present invention is to provide a flow sensor that can be realized.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a first invention includes a tubular body that forms a fluid flow path, a rectifying grid member that is disposed in the tubular body and divides the flow path into a plurality of small flow paths, and the tubular body. A wiring board disposed; and a flow rate detection element disposed on the wiring board so that the detection portion is covered with a protective film and faces any one of the plurality of small flow paths. An electrical connection portion between the detection element and the wiring board is located in a hole provided in the rectifying grid member and is isolated from the fluid .
In the present invention, the electrical connection between the flow velocity detecting element and the wiring board can be isolated from the fluid. Therefore, the connecting portion does not corrode due to adhesion of moisture or the like. In addition, since it is not necessary to project the flow velocity detection element outside the flow path, the element itself can be reduced in size, and it is not necessary to change the size of the flow velocity detection element in accordance with the shape (diameter) of the flow path. The rectifying grid member rectifies the fluid by dividing the flow path in the tube into a plurality of small flow paths. Therefore, generation | occurrence | production of a turbulent flow and a vortex can be suppressed.
[0010]
According to a second invention, in the first invention, an electrical connection portion between the flow velocity detecting element and the wiring board is resin-sealed.
In the present invention, the electrical connection between the flow velocity detecting element and the wiring board can be more reliably isolated from the fluid.
[0011]
According to a third invention, in the first or second invention, a recess having substantially the same depth as that of the element into which the flow velocity detecting element is fitted is formed on the wiring board.
In the present invention, the flow rate detecting element can be positioned by the recess and the step can be eliminated.
[0012]
According to a fourth aspect of the present invention, in the first or second aspect of the invention, the flow rate detecting element is disposed on the wiring board, and the rectifying grid member is installed on the wiring board to form substantially the same plane as the flow rate detecting element. The board part to be provided is provided.
In this invention, since the flow velocity detecting element and the plate portion form substantially the same plane, no step is generated between the flow velocity detecting element and the wiring board, and the fluid flow is not disturbed.
[0013]
According to a fifth invention, in the first, second, third or fourth invention, the wiring metal thin film of the wiring substrate is formed so as to extend from the front surface to the back surface side through the substrate. .
In this invention, the metal thin film for wiring formed on the back surface side is not exposed to the fluid. When the metal thin film for wiring on the surface side is formed only in a small part near the connection part, it is not exposed to the fluid because it is covered with the rectifying grid member.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
1 is a perspective view of a flow sensor according to the present invention, FIGS. 2A and 2B are a sectional view taken along the line II-II in FIG. 1 and an enlarged sectional view of the main part, and FIG. 3 is a sectional view taken along the line III-III in FIG. 4A and 4B are a plan view and a cross-sectional view of the flow velocity detecting element, FIG. 5 is a diagram showing a constant temperature difference circuit of the flow sensor, and FIG. 6 is a diagram showing a sensor output circuit. In the present embodiment, an example is shown in which the flow sensor 20 is used to measure the flow rate of gas (air) flowing through the intake pipe of an automobile engine.
[0015]
The flow sensor 20 includes a tubular body 21 that forms a flow path 22 through which air 15 flows, and a rectifying grid member 23 that is disposed in the tubular body 21 and divides the flow path 22 into six small flow paths 22a to 22f. The flow rate detecting element 24 and the like disposed together with the wiring board 25 in the tube body 21 are configured.
[0016]
The tube body 21 is formed of a synthetic resin or metal in a rectangular tube shape with both ends open, and is composed of an upper plate 21a, a bottom plate 21b, and left and right side wall plates 21c and 21d, and both end openings are made smaller toward the inside. It is narrowed to become. A substrate mounting recess 26 (FIG. 3) perpendicular to the axial direction of the tube body 21 is formed at the center of the upper surface of the bottom plate 21b, and both ends of the bottom plate 21b penetrate the left and right side wall plates 21c and 21d and It is open to. The width of the substrate mounting recess 26 is approximately equal to or slightly larger than the width of the wiring substrate 25, and the depth is approximately equal to the thickness of the wiring substrate 25. Such a pipe body 21 is incorporated in the bypass flow path 3 of the intake pipe 1 shown in FIG. 8 with appropriate rigidity and strength. When the tube body 21 is made of metal, it is necessary to cover it with an insulating film in order to insulate the wiring substrate 25 from the wiring metal thin film 27 (FIG. 2).
[0017]
The rectifying grid member 23 that partitions the flow path 22 into six small flow paths 22a to 22f is formed of a synthetic resin (or metal) in a flat plate shape and has a total of five partition plates 23a to 23 having appropriate rigidity and strength. 23e is integrally joined. Of the five partition plates 23a to 23e, the partition plate 23a is horizontally installed in the center of the height direction inside the tube body 21, and both left and right ends are bonded to the inner surfaces of the side wall plates 21c and 21d by an adhesive, ultrasonic welding, or the like. Are joined by. Of the remaining four partition plates 23b to 23e, the two partition plates 23b and 23c are positioned so as to be orthogonal to the upper surface side of the partition plate 23a and to divide the longitudinal direction of the partition plate 23a into approximately three equal parts. The upper end is joined to the inner surface of the upper plate 21a by an adhesive, ultrasonic welding or the like, and the lower end is joined to the upper surface of the partition plate 23a by the same adhesive, ultrasonic welding or the like. Further, the partition plates 23b and 23c are arranged to face each other so as to be parallel to the axis of the tube body 21. The remaining two partition plates 23d and 23e are arranged on the lower surface side of the partition plate 23a so as to be orthogonal to the lower partition plate 23a and directly below the upper partition plates 23b and 23c, and the upper end thereof is the partition plate. The lower surface of 23a is bonded by an adhesive, ultrasonic welding or the like, and the lower end is bonded to the flow velocity detecting element 24 and the upper surface of the wiring board 25 by an adhesive or the like. For this reason, all the cross-sectional areas in the plane orthogonal to the flow direction of the air 15 in the small flow paths 22a to 22f are substantially equal. Further, the front and rear ends of the partition plates 23a to 23e are formed as semicircular convex curved surfaces so as not to disturb the flow of the air 15. The shape that does not disturb the flow of the air 15 is not limited to a convex curved surface, and may be a triangle. Furthermore, an elongated hole 28 opened to the upper and lower surfaces is formed in the center of the lower partition plates 23d and 23e, respectively. Note that part or all of the five partition plates 23a to 23e may be manufactured by integral molding. In the case of integral molding, when the flow sensor 20 is assembled, it can be easily assembled by assembling as a structure similar to that of the second embodiment described later.
[0018]
The flow velocity detecting element 24 includes a rectangular silicon substrate 31 that is long in the width direction of the tube body 21 and is positioned by being fitted into a recess 33 (FIG. 2) provided at the center of the upper surface of the wiring substrate 25. And are fixed by an adhesive. The central part of the silicon substrate 31 constitutes a detection part 32. This detection unit 32 has a thin-walled portion, that is, a diaphragm 35 left by removing the central portion of the back surface of the silicon substrate 31 by etching to form a recess 34 (FIG. 4). In addition, one heating element (resistive heater) 36, two temperature sensors 37A and 37B constituting the indirectly heated temperature detecting means 30, and an ambient temperature sensor 38 on the silicon substrate 31 are respectively formed by a well-known thin film forming technique. Is formed. The two temperature sensors 37A and 37B are formed so as to be positioned on the upstream side and the downstream side, respectively, in the flow direction of the air 15 with the heating element 36 interposed therebetween.
[0019]
On the upper surface of the silicon substrate 31, a plurality of electrode pads 39 and a wiring metal thin film 40 are formed simultaneously with the formation of the heating element 36 and the temperature sensors 37A and 37B by a thin film forming technique. For example, a material such as platinum is deposited on the surface of the electrical insulating film formed on the surface of the silicon substrate 31 and etched into a predetermined pattern. The heating element 36 and the temperature sensors 37A and 37B are connected to the electrode pads 39. The metal thin films 40 are electrically connected to each other. Further, the upper surface of the silicon substrate 31 is protected over almost the entire surface by applying an insulating protective film 43, and only the electrode pads 39 are exposed to the outside. The electrode pads 39 are formed in the vicinity of both ends in the longitudinal direction of the silicon substrate 31 so as to be positioned directly below the partition plates 23d and 23e (FIG. 2B).
[0020]
The wiring substrate 25 is a laminated plate obtained by stacking and firing two ceramic plates 25A and 25B having the same size, and an opening portion of the side wall plate 21c in the substrate mounting recess 26 of the tubular body 21. 44a (FIG. 3) or the opening 44b of the side wall plate 21d, and both end portions project outward from the openings 44a and 44b. The thickness of the wiring substrate 25 is substantially equal to the depth of the substrate mounting recess 26. Therefore, the upper surface of the bottom plate 21b and the upper surface of the wiring board 25 form substantially the same plane. Further, the surface of the protective film 43 covering the upper surface of the flow velocity detecting element 24 and the upper surface of the wiring board 25 form substantially the same plane (FIG. 2B).
[0021]
Further, the wiring metal thin film 27 is formed on the wiring substrate 25 corresponding to each wiring metal thin film 40 of the flow velocity detecting element 24. These wiring metal thin films 27 are formed so that most of them extend on the left and right sides of the flow velocity detecting element 24 on the lower surface side of the lower ceramic plate 25B and in the longitudinal direction of the wiring board 25. The inner end is exposed to the upper surface side of the ceramic plate 35A through the through-hole 46 (FIG. 2B) formed in the upper ceramic plate 35A, and is adjacent to the electrode pad 39 of the flow velocity detecting element 24. Is forming. The portion where the electrode pad 47 is formed on the upper surface of the wiring substrate 25 and the portion where the electrode pad 39 is formed on the upper surface of the flow velocity detecting element 24 electrically connect the flow velocity detecting portion 24 and the wiring substrate 25. A connecting portion 50 to be connected is formed, and both electrode pads 39 and 47 are electrically connected by a bonding wire 48.
[0022]
In addition, the connecting portion 50 is positioned directly below the long hole 28 of the partition plates 23d and 23e, so that the connection portion 50 is covered with the partition plates 23d and 23e, and is further sealed with a synthetic resin 51. As described above, when each connecting portion 50 is sealed with the bonding wire 48 by the synthetic resin 51, covered with the partition plates 23d and 23e, and the connecting portion 50 is isolated from the air 15, the moisture contained in the air 15 and the organic A substance does not adhere to the connection part 50, and corrosion of the connection part 50 can be prevented.
[0023]
On the other hand, the other end side of the metal thin film 27 for wiring extends to the outer end of the lower surface of the ceramic plate 25 </ b> B, so that it is exposed to the outside of the tube body 21 and electrically connected to the metal thin film for wiring of the external wiring board 56. It is connected to the.
[0024]
FIG. 5 is a diagram showing a constant temperature difference circuit of the flow sensor 20. In the figure, a heating element 36, an ambient temperature sensor 38 and three fixed resistors R1, R2, R3 form a bridge circuit, and this and OP1 constitute a constant temperature difference circuit. OP1 takes the midpoint voltage of the bridge circuit, resistor R1 and heating element 36 as an inverting input, and the midpoint voltage of resistors R2 and R3 as a non-inverting input. The output of OP1 is commonly connected to one ends of resistors R1 and R2. The resistance values of the resistors R1, R2, and R3 are set so that the heating element 36 always has a constant temperature higher than the ambient temperature sensor 38.
[0025]
FIG. 6 is a diagram showing a sensor output circuit of the flow sensor 20. In the figure, two temperature sensors 37A and 37B and two fixed resistors R4 and R5 form a bridge circuit, and this and OP2 constitute a sensor output circuit.
[0026]
In the flow sensor 20 having such a structure, the pipe body 21 is arranged so that the axis of the pipe body 21 is parallel to the axis of the bypass flow path 3 in the bypass flow path 3 shown in FIG. 24 is attached in parallel with the flow direction of the air 15.
[0027]
In such a flow sensor 20, the air 15 is heated in the direction of the arrow (FIG. 4) while the heating element 36 is heated to a certain higher temperature than the ambient temperature by energizing the bridge circuit of the constant temperature difference circuit shown in FIG. When the flow is caused to flow, the resistance of the heating element 36 decreases because the heat is taken away by the air 15. For this reason, although the equilibrium state of the bridge circuit is lost, a voltage corresponding to the voltage generated between the inverting input and the non-inverting input is applied to the bridge circuit by the operational amplifier OP1, so that heat deprived by the air 15 is compensated. The amount of heat generated by the heating element 36 increases. As a result, the resistance value of the heating element 36 increases, so that the bridge circuit returns to an equilibrium state. Therefore, a voltage corresponding to the flow velocity is applied to the bridge circuit in an equilibrium state. The constant temperature difference circuit of FIG. 5 outputs the voltage between the terminals of the heating element 36 among the voltages applied to the bridge circuit at this time as a voltage output.
[0028]
When the air 15 takes the heat of the heating element 36, a temperature difference is generated between the temperature sensor 37A located upstream of the heating element 36 and the temperature sensor 37B located downstream, so that the sensor output circuit shown in FIG. The flow velocity of the air 15 can be measured by detecting the voltage difference or the resistance value difference and calculating the detection signal. The flow rate can be obtained by multiplying the measured flow velocity by the cross-sectional area of the flow path 22.
[0029]
As described above, the flow sensor 20 according to the present invention covers the electrical connection portion 50 between the flow velocity detecting element 24 and the wiring board 25 with the partition plates 23 d and 23 e constituting the rectifying grid member 23, and the air flowing in the tube body 21. 15 isolates the connecting portion 50 from the moisture, organic substances, etc. contained in the air 15 do not adhere to the connecting portion 50, and as a result, corrosion of the connecting portion 50 can be prevented. The durability and reliability of the flow sensor 20 can be improved.
[0030]
Moreover, since the connection part 50 is located in the flow path 22 of the tube body 21, it is not necessary to make the flow velocity detection element 24 protrude outside the tube body 21, and the flow velocity detection element 24 can be reduced in size. Moreover, it is not necessary to change the shape of the silicon substrate 31 according to the diameter of the flow path.
[0031]
Further, since the rectifying grid member 23 divides the flow path 22 into six small flow paths 23a to 23f, the air 15 can be rectified to prevent the occurrence of turbulent flow, vortices and the like. Furthermore, since the upper surfaces of the flow velocity detecting element 24 and the wiring board 25 are formed in substantially the same plane, there is no step that causes turbulence and vortices, and measurement accuracy can be improved.
[0032]
FIG. 7 is a cross-sectional view of a main part showing another embodiment of the present invention.
In this embodiment, the wiring board 25 is constituted by a single ceramic plate, the flow velocity detecting element 24 is installed thereon, and the plate portion 60 installed on the upper surface of the wiring board 25 is provided at the lower ends of the partition plates 23d and 23e. Each is provided so that the step between the flow velocity detecting element 24 and the wiring board 25 is eliminated. For this reason, the upper surfaces of the flow velocity detecting element 24 and the plate portion 60 form substantially the same plane. Further, in order to facilitate the work of assembling the rectifying grid member 23, the flow velocity detecting element 24, and the wiring board 25 into the tube body 21, the tube body 21 has a two-part structure so that the upper plate 21a ( 1) and the left and right side wall plates 21c and 21d are integrally formed, and the bottom plate 21b is separately manufactured and integrally joined in a subsequent process.
[0033]
Further, after the flow velocity detecting element 24 is installed on the wiring substrate 25, the electrical connection portions 50 of these two members are electrically connected by the bonding wires 48, and the connection portion 50 is sealed with the synthetic resin 51. The rectifying grid member 23 is installed on the flow velocity detecting element 24 and the wiring board 25, the connecting portion 50 is covered with the partition plates 23d and 23e, and these are integrated to form a detection unit. The detection unit is incorporated in the upper plate 21a and the left and right side wall plates 21c and 21d, and then the bottom plate 21b is fixed to the lower surface side of the wiring board 25 by ultrasonic welding or the like. In addition, since the other structure is the same as that of above-described embodiment, it shows with the same code | symbol about the thing of the same structural member, and abbreviate | omits the description.
[0034]
Even in such a structure, since the flow velocity detecting element 24 and the plate portion 60 form substantially the same plane, the flow of the air 15 is not disturbed. Further, since the wiring board 25 is formed by a single ceramic plate, there is an advantage that the wiring board 25 itself is easy and inexpensive to manufacture.
[0035]
The present invention is not limited to the above-described embodiment, and various changes and modifications can be made. For example, in the above-described embodiment, the example in which the rectifying grid 23 is configured by the five partition plates 23a to 23e has been shown. However, the horizontal partition plate 23a is omitted and the flow path 22 is divided into three small streams. You may partition into a path | route or may further increase the number of the partition plates arrange | positioned above and below the partition plate 23a. Moreover, if the electrical connection part 50 is put together on one side of the silicon substrate 31, the number of partition plates can be reduced.
Further, the flow velocity detecting element 24 and the wiring board 25 may be disposed on the upper or lower surface of the horizontal partition plate 23a. In this case, the wiring board 25 can be used as the horizontal partition plate 23a.
[0036]
In addition, the bonding wire 48 is used as an electrical wiring means for electrically connecting the electrical connection portion 50 between the flow velocity detecting element 24 and the wiring board 25, but TAB (Tape Automated Bonding: copper foil for wiring is used on the film). You may use what was formed. When TAB is used, the height of the wiring portion can be reduced, which is suitable for mass production.
[0037]
Further, in the above-described embodiment, the side temperature type sensor in which the spatial temperature distribution of the air 15 caused by the heat from the heating element 36 is biased by the flow and is detected by the two temperature sensors 37A and 37B. However, the present invention is not limited to this, and a self-heating type sensor that detects a change in electric power or a change in resistance due to heat 15 being taken away by the air 15 and detects a flow rate or a flow velocity is used. May be. Further, the number of temperature sensors is not limited to two, and may be one. In short, the flow velocity detection element 24 may be any device that can measure the flow rate or the flow velocity.
[0038]
Furthermore, in the above-described embodiment, the example used for measuring the flow rate of the air flowing through the intake pipe of the engine of the automobile has been shown. However, the present invention is not limited to this, and the flow rate of various fluids or It can be used for flow rate measurement.
[0039]
【The invention's effect】
As described above, according to the flow sensor of the present invention, since the flow velocity detection element can be reduced in size, the manufacturing cost can be reduced, and the shape of the flow velocity detection element needs to be changed according to the diameter of the flow path. Disappears. In addition, since the electrical connection between the flow velocity detecting element and the wiring board can be isolated from the measurement fluid, the connection is not corroded by the fluid, and the reliability and durability of the sensor can be improved. it can.
Further, since the flow path is divided into a plurality of small flow paths to rectify the fluid, the flow of the fluid is not disturbed and vortices are not generated, and the measurement accuracy can be improved.
[0040]
Further, in the invention in which the connecting portion between the flow velocity detecting element and the wiring board is sealed with resin, the connecting portion can be more reliably isolated from the fluid, and the reliability and durability of the sensor can be further improved. .
[0041]
Further, in the invention in which the flow velocity detection element is fitted in the recess provided in the wiring board, the flow velocity detection element can be positioned with respect to the wiring board and the step can be eliminated.
[0042]
Further, in the invention in which the plate portion that eliminates the step between the flow velocity detection element and the wiring board is provided on the rectifying grid member, the flow velocity detection element and the plate portion form substantially the same plane, so that the fluid flow is not disturbed, In addition, since the wiring board can be constituted by a single board, it is easy to manufacture the wiring board.
[0043]
Furthermore, in the invention in which the wiring metal thin film of the wiring board is formed so as to extend from the front surface to the back surface through the substrate, the wiring metal thin film formed on the back surface side may be exposed to fluid. There is no need to cover it with a protective film. In addition, the metal thin film for wiring on the front side only needs to be formed in a small part near the connection part and covered with a rectifying grid member, so that it does not corrode due to fluid contact, and the durability of the sensor Can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a flow sensor according to the present invention.
2A and 2B are a cross-sectional view taken along line II-II in FIG. 1 and an enlarged cross-sectional view of a main part.
3 is a cross-sectional view taken along line III-III in FIG.
4A and 4B are a plan view and a cross-sectional view of a flow velocity detecting element, respectively.
FIG. 5 is a diagram showing a constant temperature difference circuit of a flow sensor.
FIG. 6 is a diagram showing a sensor output circuit.
FIG. 7 is a cross-sectional view of a main part showing another embodiment of the present invention.
FIG. 8 is a diagram showing a conventional flow sensor used for measuring a flow rate of gas (air) flowing through an intake pipe of an automobile engine.
9 is a cross-sectional view taken along line IX-IX in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Intake pipe, 3 ... Bypass flow path, 15 ... Air, 20 ... Flow sensor, 21 ... Tube, 22 ... Flow path, 22a-22f ... Small flow path, 23 ... Rectification grid member, 24 ... Flow velocity detection element, DESCRIPTION OF SYMBOLS 25 ... Wiring board | substrate, 27 ... Metal thin film for wiring, 32 ... Detection part, 33 ... Recessed part, 43 ... Protective film, 50 ... Connection part, 48 ... Bonding wire, 51 ... Synthetic resin, 60 ... Plate part.

Claims (5)

A tubular body forming a fluid flow path; a rectifying grid member disposed in the tubular body for partitioning the flow path into a plurality of small flow paths; a wiring board disposed in the tubular body; And a flow velocity detecting element disposed on the wiring board so as to face any one of the plurality of small flow paths, and an electrical connection portion between the flow velocity detecting element and the wiring board. A flow sensor, wherein the flow sensor is located in a hole provided inside the rectifying grid member and is isolated from the fluid . The flow sensor according to claim 1,
A flow sensor characterized in that an electrical connection portion between a flow velocity detecting element and a wiring board is sealed with resin. The flow sensor according to claim 1 or 2,
A flow sensor characterized in that a recess having substantially the same depth as that of the element into which the flow velocity detecting element is fitted is formed on the wiring board. The flow sensor according to claim 1 or 2,
A flow sensor comprising: a flow velocity detecting element disposed on a wiring board; and a plate portion that is installed on the wiring board and that forms a substantially same plane as the flow velocity detecting element. The flow sensor according to claim 1, 2, 3 or 4,
A flow sensor, wherein a wiring metal thin film of a wiring board is formed so as to penetrate the board from the front surface and extend to the back surface side.

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