WO2021090927A1 - Physical quantity measuring device, and method for manufacturing same - Google Patents

Abstract

This physical quantity measuring device is provided with a bypass housing (24) made of resin, and a conductive portion (90) that is electrically conductive. The bypass housing (24) is insulating and forms a bypass passage (30) through which a fluid flows. The conductive portion (90) is formed in such a way as to extend in a planar shape over at least one of a wall surface (24b), which is an outer surface of the bypass housing (24), and a wall surface (24a), which is an inner surface of the bypass housing that forms the bypass passage (30). The physical quantity measuring device has a configuration in which electric charge is discharged from the conductive portion (90) to ground (45).

Description

Physical quantity measuring device and its manufacturing method Cross-reference to related applications

This application is based on Japanese Patent Application No. 2019-203488 filed on November 8, 2019, the contents of which are incorporated herein by reference.

This disclosure relates to a physical quantity measuring device and a method for manufacturing the same.

Conventionally, there is known a flow meter having a housing having a bypass passage branching from the main passage and a flow rate detecting unit provided in the bypass passage to measure the flow rate of gas flowing through the main passage. When using this type of flow meter, if foreign matter such as dust flowing through the bypass passage is charged, the flow rate detection unit may be charged and the characteristics of the flow meter may be deviated. The characteristic deviation means that the output characteristic of the flow meter changes with respect to the gas flow rate measured by the flow meter.
On the other hand, in Patent Document 1, the resin material mixed with carbon fibers is used for resin molding of the housing, so that the housing is imparted with conductivity. In this configuration, even if an electric charge is applied to the housing by a foreign substance flowing through the bypass passage, the electric charge is released from the housing to the outside by the carbon fiber, and the electric charge is less likely to be accumulated in the housing. That is, the charging of the housing is suppressed.

German Patent Application Publication No. 102014218579

However, in the above-mentioned Patent Document 1, when the content of carbon fiber in the material for resin molding is insufficient, the charge suppressing function of the housing is not properly exhibited, and there is a concern that electric charge is accumulated in the housing. Further, when the material for resin molding does not contain carbon fibers, it is not possible to impart the charge suppressing function to the housing, and there is a concern that the housing will be charged. When the housing is charged as described above, there is a concern that the measurement accuracy of the physical quantity measuring device for measuring the physical quantity such as the flow rate may be lowered due to the occurrence of characteristic deviation.

The purpose of this disclosure is to improve the measurement accuracy of the physical quantity measuring device.

According to one aspect of the present disclosure, a physical quantity measuring device for measuring a physical quantity of a fluid has an insulating property and has a resin bypass housing forming a bypass passage through which the fluid flows, and a physical quantity of the fluid flowing through the bypass passage. A physical quantity detecting unit that outputs a corresponding detection signal and a conductive unit having conductivity formed on at least one of the outer surface of the bypass housing and the inner surface of the bypass housing forming the bypass passage are provided, and the electric charge is charged from the conductive unit to the ground. Is released.

According to such a configuration, the charge suppressing function of the housing can be improved by retrofitting the housing with a conductive portion by heating or the like after molding the housing with resin. In this case, the housing and the physical quantity detecting unit are less likely to be charged, so that the physical quantity measuring device can improve the measurement accuracy.

From another point of view, the manufacturing method of the physical quantity measuring device for measuring the physical quantity of the fluid is to prepare a resin bypass housing which has an insulating property and forms a bypass passage through which the fluid flows, and by heat. It includes forming a conductive portion having conductivity on at least one of the outer surface of the bypass housing and the inner surface forming the bypass passage by carbonization.

According to such a method, the charge suppressing function of the housing can be improved by retrofitting the resin housing with a conductive portion by heating or the like. In this case, the housing and the physical quantity detecting unit are less likely to be charged, so that the physical quantity measuring device can improve the measurement accuracy.

Note that the reference symbols in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is a figure which shows the air flow meter of 1st Embodiment and the intake pipe to which it attached. It is a front view of the air flow meter of FIG. FIG. 3 is a view taken along the line III in FIG. It is an IV arrow view in FIG. It is a V arrow view in FIG. FIG. 6 is a sectional view taken along line VI-VI in FIG. It is sectional drawing of VII-VII in FIG. It is VIII arrow view in FIG. It is a figure corresponding to FIG. 2, and is the figure which showed the conductive part. It is a figure corresponding to FIG. 3, and is the figure which showed the conductive part. It is a figure corresponding to FIG. 4, and is the figure which showed the conductive part. It is a figure corresponding to FIG. 5, and is the figure which showed the conductive part. It is a figure which showed the flow of the process of forming a conductive part to a housing. It is a figure for demonstrating the process of forming a conductive part in a housing. It is a figure for demonstrating the distance between patterns and the depth of a pattern. It is sectional drawing of the bypass housing. It is a figure which shows the ab plane of graphite which constitutes the carbonized part in FIG. 15B. It is the figure which showed the air flow meter of 2nd Embodiment, and is the figure corresponding to the VIII arrow view in FIG. It is a figure showing the air flow meter of the 2nd Embodiment, and is the figure corresponding to the arrow III view in FIG. It is the figure which showed the air flow meter of 2nd Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is the figure which showed the air flow meter of 3rd Embodiment, and is the figure corresponding to the VIII arrow view in FIG. It is the figure which showed the air flow meter of 3rd Embodiment, and is the figure corresponding to the arrow III view in FIG. It is the figure which showed the air flow meter of 3rd Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a front view of the air flow meter of 4th Embodiment. It is a figure which showed the air flow meter of 4th Embodiment, and is the figure corresponding to the arrow III view in FIG. It is a figure showing the air flow meter of 4th Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a figure showing the air flow meter of 5th Embodiment, and is the figure corresponding to the VIII arrow view in FIG. It is the figure which showed the air flow meter of 5th Embodiment, and is the figure corresponding to the arrow III view in FIG. It is a figure showing the air flow meter of 5th Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a front view of the air flow meter of the sixth embodiment. It is the figure which showed the air flow meter of 6th Embodiment, and is the figure corresponding to the arrow III view in FIG. It is a figure showing the air flow meter of 6th Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a front view of the air flow meter of the 7th embodiment. It is a figure which showed the air flow meter of 7th Embodiment, and is the figure corresponding to the arrow III view in FIG. It is a figure showing the air flow meter of 7th Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a figure showing the air flow meter of 7th Embodiment, and is the figure corresponding to the V arrow view in FIG. It is a figure showing the air flow meter of 8th Embodiment, and is the figure corresponding to the VI-VI sectional view in FIG. It is a figure showing the air flow meter of 8th Embodiment, and is the figure corresponding to the sectional view VII-VII in FIG. It is a figure showing the air flow meter of the 9th Embodiment, and is the figure corresponding to the VI-VI sectional view in FIG. It is a figure showing the air flow meter of the 9th Embodiment, and is the figure corresponding to the sectional view VII-VII in FIG. It is a figure showing the air flow meter of the tenth embodiment, and is the figure corresponding to the VI-VI cross-sectional view in FIG. It is a figure showing the air flow meter of the tenth embodiment, and is the figure corresponding to the sectional view VII-VII in FIG. It is the figure which showed the air flow meter of 11th Embodiment, and is the VI-VI sectional view in FIG. It is a figure showing the air flow meter of 11th Embodiment, and is the figure corresponding to the sectional view VII-VII in FIG. It is a front view of the air flow meter of the twelfth embodiment. It is a figure which showed the air flow meter of the twelfth embodiment, and is the figure corresponding to the arrow III view in FIG. It is a figure showing the air flow meter of the twelfth embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a figure showing the air flow meter of the twelfth embodiment, and is the figure corresponding to the V arrow view in FIG. It is a figure showing the air flow meter of the thirteenth embodiment, and is the figure corresponding to the VI-VI sectional view in FIG. It is a figure showing the air flow meter of the thirteenth embodiment, and is the figure corresponding to the sectional view VII-VII in FIG. It is the figure which showed the air flow meter of 14th Embodiment, and is the figure corresponding to the arrow III view in FIG. It is a figure showing the air flow meter of 14th Embodiment, and is the figure corresponding to the IV arrow view in FIG. It is a figure showing the air flow meter of the fifteenth embodiment, and is the figure corresponding to the VI-VI cross-sectional view in FIG. It is a figure showing the air flow meter of the fifteenth embodiment, and is the figure corresponding to the sectional view VII-VII in FIG. It is a figure for demonstrating the manufacturing method of the air flow meter which concerns on 16th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 17th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 17th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 18th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 18th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 19th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 19th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 20th Embodiment. It is a figure showing the pattern formed on the surface of the air flow meter which concerns on 20th Embodiment. It is a figure showing the conductive part formed on the surface of the bypass housing of the air flow meter which concerns on 21st Embodiment. It is a perspective view of the resin member which constitutes the housing of the air flow meter which concerns on 1st Embodiment. It is sectional drawing of LX-LX in FIG. 59. FIG. 6 is a cross-sectional view schematically showing how the filler is caught in the carbide. It is an enlarged view of the front surface of the resin member of 1st Embodiment. It is sectional drawing of LXIII-LXIII in FIG. 62.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each of the following embodiments, the same or equal parts are designated by the same reference numerals, and the description thereof will be omitted.

(First Embodiment)
The physical quantity measuring device according to this embodiment will be described. First, the basic configuration of the physical quantity measuring device will be described with reference to FIGS. 1 to 15C and FIGS. 59 to 63. As shown in FIG. 1, the physical quantity measuring device is configured as an air flow meter 20 mounted on a vehicle. The air flow meter 20 is provided in the intake passage 80 as the main passage, and has a function of measuring physical quantities such as the flow rate and temperature of the intake air supplied to the internal combustion engine. Further, the air flow meter 20 can also have a function of measuring physical quantities such as humidity and pressure of intake air.

The air flow meter 20 is arranged in the intake passage 80 on the downstream side of the air cleaner (not shown) and on the upstream side of the throttle valve (not shown). In this case, in the intake passage 80, the air cleaner side is the upstream side and the combustion chamber side is the downstream side for the air flow meter 20.

As shown in FIG. 1, the air flow meter 20 is detachably attached to an intake pipe 82a forming an intake passage 80. The air flow meter 20 is inserted into an air flow insertion hole 82b formed so as to penetrate the tubular wall of the intake pipe 82a, and at least a part thereof is located in the intake passage 80. The intake pipe 82a has an annular pipe flange 82c extending outward from the airflow insertion hole 82b. The intake pipe 82a includes a pipe formed of a synthetic resin material or the like. Hereinafter, the longitudinal direction of the intake passage 80, that is, the direction in which the intake air flows in the intake passage 80 will be referred to as a flow direction.

As shown in FIGS. 1 to 6, the air flow meter 20 includes a housing 21, a flow rate detection unit 22, and an intake air temperature sensor 23. The flow rate detection unit 22 corresponds to a physical quantity detection unit that outputs a detection signal according to the physical quantity of the fluid, and the intake air temperature sensor 23 corresponds to a temperature sensor that detects the temperature of the fluid. The housing 21 is formed to contain at least resin. In the air flow meter 20, since the housing 21 is attached to the intake pipe 82a, the flow rate detecting unit 22 is in a state where it can come into contact with the intake air flowing through the intake passage 80.

The housing 21 has a bypass housing 24, a ring holding portion 25, a flange portion 27, a connector portion 28, a caulking portion 29a, and a protective protrusion 29b. An O-ring 26 is attached to the ring holding portion 25. The ring holding portion 25 is a portion that is internally fitted into the airflow insertion hole 82b via the O-ring 26.

The bypass housing 24 protrudes from the ring holding portion 25 toward the intake passage 80. Hereinafter, the ring holding portion 25 side of the bypass housing 24 will be referred to as a housing base end, and the side of the bypass housing 24 opposite to the ring holding portion 25 will be referred to as a housing tip.

The flange portion 27 is arranged outside the intake pipe 82a with respect to the ring holding portion 25, that is, outside the intake passage 80, and covers the airflow insertion hole 82b from the outside of the intake pipe 82a.

The connector portion 28 is a portion that surrounds a plurality of connector terminals 28a, and corresponds to a terminal protection portion that protects the connector terminals 28a. One of the plurality of connector terminals 28a is a ground terminal, which is connected to an external ground 45.

The caulking portion 29a is a portion that supports and fixes the ground terminal 23b and the signal terminal 23c of the intake air temperature sensor 23, which will be described later. The housing 21 is provided with a pair of caulking portions 29a. Each caulked portion 29a is formed with a through hole for inserting the ground terminal 23b and the signal terminal 23c of the intake air temperature sensor 23.

The intake air temperature sensor 23 has a temperature sensing element 23a that senses the temperature of the intake air, a ground terminal 23b, and a signal terminal 23c. The temperature sensitive element 23a is fixed to the housing 21 by being heat-caulked with the ground terminal 23b and the signal terminal 23c inserted into the through holes formed in the caulking portion 29a. The ground terminal 23b and the signal terminal 23c of the intake air temperature sensor 23 are fixed to the pair of through holes 251 formed in the ring holding portion 25 by soldering. Further, the signal terminal 23c of the intake air temperature sensor 23 is electrically connected to a predetermined connector terminal excluding the ground terminal. The ground terminal 23b of the intake air temperature sensor 23 is connected to the connector terminal 28a connected to the ground 45. The ground terminal 23b of the intake air temperature sensor 23 is grounded to the ground 45 via the connector terminal 28a. The intake air temperature sensor 23 outputs a detection signal according to the intake air temperature sensed by the temperature sensing element 23a.

Since the intake air temperature sensor 23 is arranged outside the housing 21, it is necessary to protect the intake air temperature sensor 23 from an object close to the intake air temperature sensor 23 from the outside of the housing 21. Therefore, the housing 21 is provided with two protective protrusions 29b that protect the housing 21 from an object close to the intake air temperature sensor 23 from the outside of the housing 21.

Each protective protrusion 29b projects laterally from the bypass housing 24. One of the protective protrusions 29b is arranged on the upstream side in the flow direction from the intake air temperature sensor 23, and the other of the protective protrusions 29b is arranged on the downstream side in the flow direction from the intake air temperature sensor 23. The protruding dimension of the protective protrusion 29b from the bypass housing 24 is larger than the distance of the intake air temperature sensor 23 from the bypass housing 24. The protective protrusion 29b suppresses damage to the intake air temperature sensor 23 due to contact between the intake air temperature sensor 23 and the intake pipe 82a when the air flow meter 20 is attached to the intake pipe 82a.

As shown in FIGS. 6 and 7, the bypass housing 24 forms a bypass passage 30 through which a part of the intake air flowing through the intake passage 80 flows. The bypass passage 30 has a passage passage 31 and a measurement passage 32, and the passage passage 31 and the measurement passage 32 are formed by the internal space of the bypass housing 24.

The passage passage 31 penetrates the tip end portion of the bypass housing 24 in the flow direction, and has an inflow port 33a which is an upstream end portion and an outflow outlet 33b which is a downstream end portion. The measurement passage 32 is a branch passage branched from the intermediate portion of the passage passage 31, and has a measurement outlet 33c which is a downstream end portion. One measurement outlet 33c is provided on each side surface of the bypass housing 24.

As shown in FIGS. 6 and 7, the measurement passage 32 has a folded shape that is folded back at an intermediate position. The measurement passage 32 has a detection path 32a in which the detection element 22b of the flow rate detection unit 22 is arranged, an introduction path 32b for introducing the intake air into the detection path 32a, and an discharge path 32c for discharging the intake air from the detection path 32a. Have. The introduction path 32b extends from the passage 31 toward the base end side of the housing, and the discharge path 32c extends from the detection path 32a toward the tip end side of the housing.

In the measurement passage 32, the intake air that has flowed in from the passage passage 31 once flows toward the base end side of the housing, and then makes a U-turn by passing through the detection path 32a and flows toward the front end side of the housing. The U-turn-shaped passage makes it difficult for foreign matter such as dust and dirt to reach the detection element 22b even if it is mixed with the intake air.

Further, as shown in FIGS. 3, 4, and 8, the bypass housing 24 has a cover 24c that covers the end portion of the discharge path 32c on the housing tip side from the outside. One cover 24c is provided on each side surface of the bypass housing 24. A measurement outlet 33c for discharging intake air is formed between the bypass housing 24 and the cover 24c. The intake air sucked into the measurement passage 32 from the passage passage 31 is discharged to the outside of the bypass housing 24 from the discharge passage 32c through the measurement outlet 33c.

As shown in FIGS. 6 and 7, the flow rate detection unit 22 is a physical quantity detection unit that outputs a detection signal according to the physical quantity of the fluid flowing through the measurement passage 32. In the first embodiment, the flow rate detection unit 22 outputs a detection signal according to the flow rate of the intake air flowing through the detection path 32a.

The flow rate detection unit 22 performs signal processing of a detection element 22b that outputs a signal according to the flow rate of air flowing through the measurement passage 32, a detection board 22a on which the detection element 22b is mounted, and a signal output from the detection element 22b. It has an integrated circuit 22c.

The detection element 22b includes a heat generating portion such as a heat generating resistor that generates heat when energized, a first temperature detecting portion arranged on the upstream side of the air flow of the heat generating portion, and a second temperature detection arranged on the downstream side of the air flow of the heat generating portion. It has a part (neither is shown).

The detection element 22b transmits a signal based on the temperature difference between the detection temperature of the first temperature detection unit and the detection temperature of the second temperature detection unit when the heat generating unit is energized, according to the flow rate of the air flowing through the measurement passage 32. Output as. If foreign matter such as charged dust adheres to the first temperature detection unit or the second temperature detection unit of the detection element 22b, the balance of the detection temperature is lost and the characteristics are deviated.

The detection board 22a forms an outer shell of the flow rate detection unit 22, and the detection element 22b is arranged at the end of the board surface of the detection board 22a.

Next, the deterioration of the detection accuracy of the air flow meter 20 due to the adhesion of foreign matter to the flow rate detection unit 22 will be described. In the first embodiment, as described above, the shape of the measurement passage 32 makes it difficult for foreign matter to reach the flow rate detection unit 22. However, it is not possible to completely eliminate the arrival of foreign matter at the flow rate detecting unit 22. Further, when the foreign matter is charged, the foreign matter may adhere to the flow rate detecting unit 22 and cause a deviation in the characteristics of the air flow meter 20.

Regarding this characteristic deviation, there is a conventional technique for suppressing the charge of foreign matter by mixing an antistatic agent into the resin material of the housing. However, in the case of a housing containing an antistatic agent, the resin material is reduced by the amount of the antistatic agent, so that the moldability of the housing tends to decrease. In addition, since the amount of glass fiber is reduced by the amount of the antistatic agent, the strength of the housing tends to decrease. The decrease in strength causes a decrease in durability. That is, the problems are the deterioration of the moldability and the durability of the housing due to the mixing of the antistatic agent in the resin material.

Hereinafter, a configuration for suppressing a deviation in the characteristics of the air flow meter 20 while avoiding a decrease in moldability and durability of the housing 21 will be described.

In FIGS. 1 to 8, the conductive portion 90 is omitted in order to make it easier to see the shape of each portion of the air flow meter 20. However, as shown in FIGS. 9 to 12, the actual air flow meter 20 provides conductivity around the entire outer wall surface 24b, which is the outer surface of the bypass housing 24, and the through hole 251 formed in the ring holding portion 25. A grid-like pattern 901 is formed as the conductive portion 90 to have.

The housing 21 has an insulating property. The housing 21 has a base polymer made of a resin material and having insulating properties, and a filler having higher strength and insulating properties than the base polymer. The base polymer has excellent moldability. The filler is a reinforcing material that reinforces the housing 21 and contains glass fibers.

The conductive portion 90 is formed by carbonizing the surface of the housing body 91 by irradiating the surface of the housing body 91 with laser light. The conductive portion 90 has conductivity because it contains carbides which are aggregates of graphite. That is, the conductive portion 90 having conductivity is formed by irradiating the surface of the insulating housing 21 with laser light. Then, the electric charge is discharged from the conductive portion 90 to the ground 45. The conductive portion 90 prevents the housing 21 from being charged, and suppresses the deviation of the characteristics of the air flow meter 20. As a result, the measurement accuracy of the physical quantity measuring device can be improved.

In the air flow meter 20 of the present embodiment, the conductive portion 90 is configured by a grid-like pattern 901. That is, the conductive portion 90 is formed by forming conductive carbides on the surface of the housing 21 as a grid-like pattern 901. However, the grid-like pattern 901 is an example of the shape of the conductive portion 90. The lattice-shaped pattern 901 has a first conductive portion 901a extending in one direction and a second conductive portion 901b extending in a direction intersecting the first conductive portion 901a. In the present embodiment, the first conductive portion 901a and the second conductive portion 901b are formed so as to be orthogonal to each other in a + (plus) sign.

The spacing between the grid-like patterns 901 is about 2 mm, and the depth of the grid-like pattern 901 is about 300 microns.

The pattern 901 is connected to the ground terminal 23b of the intake air temperature sensor 23 which is exposed and arranged on the outside of the housing 21. Specifically, the pattern 901 is a ground terminal of the intake air temperature sensor 23 connected to the ground 45 via the connector terminal 28a around the caulking portion 29a fixing the ground terminal 23b and the signal terminal 23c of the intake air temperature sensor 23. It is connected to 23b.

When an electric charge is accumulated in the pattern 901, this electric charge is discharged to the ground 45 through the ground terminal 23b and the connector terminal 28a of the intake air temperature sensor 23.

Further, for example, when the first conductive portion 901a is arranged so as to extend in the air flow direction, it is possible to make the air flow less likely to be disturbed. Further, when the second conductive portion 901b is arranged so as to extend in a direction intersecting the air flow direction, the charge imparting rate from the foreign matter to the second conductive portion 901b can be increased.

Next, a method of manufacturing the air flow meter 20 will be described with reference to FIGS. 13 to 14. Here, an example in which the conductive portion 90 is formed on the surface of the bypass housing 24 of the air flow meter 20 by laser processing will be described.

First, as shown in FIG. 14, the operator prepares an air flow meter 20 including a resin bypass housing 24 in S100. An intake air temperature sensor 23 is attached to the bypass housing 24 in advance. Then, the air flow meter 20 is fixed to the processing jig.

Next, the worker carries out the first heating step in S200. Specifically, the operator uses a laser machine to irradiate the surface of the bypass housing 24 with a laser in a grid pattern to heat the surface of the bypass housing 24. Here, laser irradiation is performed with high output. At this time, heat of 2000 ° C. or higher is applied to the surface of the bypass housing 24, the bond of the polymer used as the material is cleaved, and the constituent elements other than carbon are decomposed gases such as carbon dioxide, carbon monoxide, nitrogen, and hydrogen. It is detached and carbonized. By such carbonization, a conductive portion 90 containing graphite, which is a carbide, is formed on the surface of the bypass housing 24. Conductivity is imparted to the conductive portion 90.

Next, the worker carries out a second heating step called fume processing in S300. Specifically, the operator uses a laser machine to irradiate the entire surface of the bypass housing 24 with a laser at a higher speed to heat the surface of the bypass housing 24. Here, the laser irradiation is performed with a weaker output than the previous first heating step. As a result, dust or the like called fume generated when the laser irradiation is performed in the grid pattern is removed. Further, the volume resistivity of the conductive portion 90 is adjusted to a desired value. The laser-irradiated region is whitened by this fume processing. In this way, the air flow meter 20 is completed.

Next, the movement of electric charge in the conductive portion 90 formed in the bypass housing 24 will be described with reference to FIG. 15A. FIG. 15A schematically shows a cross-sectional view of a portion where a grid pattern 901 is formed on the outer wall surface 24b of the bypass housing 24. Specifically, a cross-sectional view of a portion where the first conductive portion 901a (that is, the carbonized portion 15) forming the grid-like pattern 901 is formed is schematically shown.

First, the movement of electric charge in the surface direction of the outer wall surface 24b of the bypass housing 24 will be described.

If the distance from the charge to the grid pattern 901 is too long, the charge will not move due to discharge. According to the studies by the present inventors, it has been found that if the distance from the electric charge to the conductive portion 90 is within 1 mm, the electric charge is relatively stably transferred by the electric discharge.

In the air flow meter 20 of the present embodiment, the distance between the first conductive portions 901a constituting the grid pattern 901 is less than 2 mm. Therefore, in the region where the grid pattern 901 is formed, the grid pattern 901 is reached within 1 mm from any position. Therefore, it is possible to relatively stably transfer the charge due to the discharge.

Further, in the air flow meter 20 of the present embodiment, the depth of the first conductive portion 901a constituting the grid pattern 901 is about 300 microns. That is, the distance between the first conductive portions 901a forming the grid-like pattern 901 is larger than the depth of the first conductive portions 901a forming the grid-like pattern 901. As described above, it is preferable that the distance between the first conductive portions 901a forming the grid-like pattern 901 is larger than the depth of the first conductive portions 901a forming the grid-like pattern 901. Further, the plate thickness of the housing 21 of the present embodiment is, for example, about 1 mm.

Further, since the distance between the first conductive portions 901a forming the grid pattern 901 is larger than the depth of the first conductive portions 901a forming the grid pattern 901, the conductive portion 90 is formed. The number of patterns 901 can be reduced. Therefore, the work load for forming the conductive portion 90 can be reduced, and the work cost can be reduced. Further, since the depth of the first conductive portion 901a forming the grid-like pattern 901 is shallower than the distance between the first conductive portions 901a forming the grid-like pattern 901, the strength due to the conductive portion 90 being made too deep. It is also possible to prevent the decrease.

Next, the movement of electric charge from the inner wall surface 24a side, which is the inner surface of the bypass housing 24, to the outer wall surface 24b side will be described.

The wall thickness between the inner wall surface 24a and the outer wall surface 24b of the bypass housing 24 is such that the thickness is dielectric breakdown between one surface of the bypass housing 24 in which the conductive portion 90 is formed and the other surface in which the conductive portion 90 is not formed. It is a length that can be discharged by. When the potential of the inner wall surface 24a of the bypass housing 24 rises, a discharge due to dielectric breakdown occurs between the inner wall surface 24a and the grid pattern 901 of the outer wall surface 24b. This phenomenon is likely to occur in a graphite layer having a negatively charged static electricity of -1 kV or less and a resin product having a plate thickness of 0.5 to 2.0 mm, which is likely to attract positively charged dust or dust.

When a discharge occurs due to dielectric breakdown between the inner wall surface 24a of the bypass housing 24 and the grid pattern 901 of the outer wall surface 24b, as shown in FIG. 15A, the electric charge 77 of the inner wall surface 24a becomes a grid pattern of the outer wall surface 24b. Move to pattern 901.

When such discharge and dielectric breakdown occur at a plurality of positions, the electric charge 77 accumulated on the inner wall surface 24a is discharged to the ground 45 through the grid pattern 901 and the connector terminal 28a. When the positive charge or the negative charge disappears from the inner wall surface 24a in this way, the adhesion of foreign matter to the detection element 22b of the flow rate detection unit 22 is suppressed, and the characteristic deviation of the flow rate detection unit 22 is suppressed.

Next, the structure of the housing 21 will be described.

The housing 21 is made of a resin member 10. The resin member 10 is composed of a resin material containing a filler and an insulating base polymer as main components. As shown in FIG. 15B, an alignment layer 12 is formed in the vicinity of the surface 11 of the resin member 10. The alignment layer 12 contains a large number of fillers 13 oriented in a direction parallel to the surface 11 (hereinafter, the surface direction), and a base polymer 14 filled between the fillers 13.

The resin member 10 has a carbonized portion 15 that imparts conductivity and thermal conductivity. The carbonized portion 15 contains, for example, graphite which is a carbide of the base polymer 14. As shown in FIG. 15C, the carbide 66 is, for example, graphite composed of carbon atoms in a bonded state with each other, and electrons are generated by leaving one electron out of four outer shell electrons belonging to the carbon atom. Since it is in a movable state, it conducts. As will be described later, the carbide 66 is not limited to graphite, but may be conductive carbon.

The carbonized portions 15 are formed in a grid pattern and form a conductive pattern. This conductive pattern can also be used as a wiring circuit in an electronic device such as an air flow meter 20 or a rotation angle sensor. When the carbide portion 15 is used as the wiring circuit for transmitting an electric signal in this way, the volume resistivity of the generated carbide 66 is at least 1.0 × 10 ^-3 Ωm or less, preferably 1.0 × 10 ^-4 Ωm or less. More preferably, it is 1.0 × ^10-5 Ωm or less. The carbonized portion 15 may have another pattern such as a stripe shape. Further, the carbonized portion 15 is not limited to the pattern shape, but may be formed into a film shape. Further, the carbonized portion 15 is not limited to the wiring circuit, and may be used for, for example, an electromagnetic shield, an antistatic circuit, an antistatic agent, a heat radiating member, and the like.

Next, the resin member 10 constituting the housing 21 of the air flow meter 20 according to the present embodiment will be described with reference to FIGS. 59 to 61. As shown in FIGS. 59, 60 and 61, the base portion 61 has a base polymer 14 formed of a resin material and having an insulating property, and a filler 13 having a strength higher than that of the base polymer 14. The base polymer 14 constitutes the resin portion of the base portion 61. The filler 13 is a reinforcing member that reinforces the base portion 61. The base portion 61 is reinforced by the filler 13 mixed with the base polymer 14.

The carbonized portion 15 is a conductive portion 90 provided on the outer surface 62 of the base portion 61 and having conductivity by containing the carbide 66. A plurality of carbonized portions 15 are formed so as to extend linearly. The plurality of carbonized portions 15 are pattern portions arranged in a pattern, and form a wiring pattern. The carbonized portion 15 constitutes the first conductive portion 901a and the second conductive portion 901b shown in FIGS. 9 to 12. The first conductive portion 901a and the second conductive portion 901b are each composed of carbonized portions 15 extending in an elongated shape. The first conductive portion 901a and the second conductive portion 901b are examples of the shape of the carbonized portion 15.

More specifically, the carbonized portion 15 has a plurality of first conductive portions 901a and a plurality of second conductive portions 901b. A plurality of linear first conductive portions 901a extend in parallel to the outer surface 62 of the base portion 61, and a plurality of linear second conductive portions 901b extend in parallel so as to be orthogonal to the first conductive portion 901a.

The carbide 66 is a conductive carbon (that is, conductive carbon). The carbide material forming the carbide 66 is a conductive material, such as a carbon material such as graphite, carbon powder, carbon fiber, nanocarbon, graphene or carbon micromaterial. Nanocarbons include, for example, carbon nanotubes, carbon nanofibers and fullerenes.

As shown in FIGS. 60 and 61, the resin member 10 includes a skin layer 63 extending along the outer surface 62 of the base portion 61, and a core layer 64 provided inside the skin layer 63. The skin layer 63 is a surface layer portion that forms the outer surface 62 of the base portion 61, and is a solidified layer that is a portion of the molten resin that is solidified in contact with the inner surface of the mold during resin molding of the base portion 61. The core layer 64 is a fluidized bed that flows inside the solidified layer of the molten resin during resin molding of the base portion 61. The outer surface 62 of the base portion 61 is the outer surface of the skin layer 63 and also the outer surface of the resin member 10.

The outer surface 62 has a groove-shaped concave surface 65 recessed on the core layer 64 side. The carbonized portion 15 is provided so as to extend from the skin layer 63 toward the core layer 64 on the groove-shaped concave surface 65. The carbonized portion 15 is one in which at least a part of the skin layer 63 is carbonized. As the material of the base polymer 14, which is the resin constituting the skin layer 63 and the core layer 64, a material containing at least a six-membered ring of carbon (that is, a benzene ring) is used.

At least the core layer 64 of the skin layer 63 and the core layer 64 forms the base portion 61. In the present embodiment, the carbonized portion 15 is provided in the skin layer 63 at a position separated from the core layer 64. That is, the groove-shaped concave surface 65 does not reach the core layer 64, and the carbonized portion 15 is provided so as to be adjacent only to the skin layer 63. Both the skin layer 63 and the core layer 64 form the base portion 61.

As shown in FIGS. 59 and 60, in the skin layer 63, more fillers 13 are oriented so as to extend in a predetermined direction along the outer surface 62 of the base portion 61 as compared with the core layer 64. Hereinafter, the filler 13 oriented so as to extend in a predetermined direction will be referred to as “aligned filler 13”. The carbonized portion 15 extends in a direction intersecting the alignment filler 13. In particular, in the seventh embodiment, the carbonized portion 15 extends in a direction orthogonal to the alignment filler 13.

As shown in FIG. 61, the carbonized portion 15 is formed by gathering a large number of carbides 66. In the filler 13, at least a part of the filler 13 enters the carbonized portion 15 to regulate the separation of the carbonized portion 15 from the base portion 61. That is, the filler 13 is a regulatory member that regulates the separation of the carbide 66 from the carbonized portion 15. As the material of the filler 13, as described in the first embodiment, a fibrous, powdery or plate-like material can be used. In the seventh embodiment, a fiber material such as a flame-retardant fiber, a glass fiber, or a carbon fiber is used as the material of the filler 13, and the fiber portion is formed by this. In FIG. 61, the hatching is omitted in order to avoid complication.

Of the fillers 13 contained in the base portion 61, those protruding from the groove-shaped concave surface 65 are held by the base portion 61 at one end and are caught by the carbonized portion 15 at the other end, so that the carbonized portion 15 and the base portion are caught. It strengthens the connection with 61. By using a fiber material as the material of the filler 13, the length of catching can be lengthened. In particular, since the alignment filler 13 intersects in the extending direction of the carbonized portion 15, it easily protrudes from the groove-shaped concave surface 65 and easily gets caught in the carbonized portion 15. Further, a part of the alignment filler 13 penetrates the carbide 66 in the carbonized portion 15, and effectively suppresses the falling off of the carbide 66.

As described above, the housing 21 is composed of a resin member 10 formed of a resin material. Further, the resin member 10 is provided on a base portion 61 having a base polymer 14 formed of a resin material and having an insulating property, a filler 13 having a strength higher than that of the base polymer 14, and an outer surface 62 of the base portion 61. It is provided with a carbonized portion 15 that is conductive by containing the carbide 66. The base portion 61 is reinforced by the filler 13 mixed with the base polymer 14. Further, in the filler 13, at least a part of the filler 13 enters the carbonized portion 15 to regulate the separation of the carbonized portion 15 from the base portion.

Further, the resin member 10 includes a skin layer 63 extending along the outer surface 62 of the base portion 61, and a core layer 64 provided inside the skin layer 63. Further, at least the core layer 64 of the skin layer 63 and the core layer 64 forms the base portion 61, and the outer surface 62 of the base portion 61 has a groove-shaped concave surface 65 recessed on the core layer 64 side. The carbonized portion 15 is provided so as to extend from the skin layer 63 toward the core layer 64 on the groove-shaped concave surface 65.

According to this, since the carbonized portion 15 is provided so as to extend from the skin layer 63, which has the same orientation of the filler 13 and easily regulates the detachment of the carbonized portion 15, toward the core layer 64, the core of the carbonized portion 15 is provided. Withdrawal from layer 64 can be further suppressed.

Further, the carbonized portion 15 is provided at a position separated from the core layer 64 in the skin layer 63. According to this, since the carbonized portion 15 is not provided in the core layer 64, the carbonized portion 15 can be more effectively suppressed from being separated from the core layer 64.

The carbonized portion 15 extends in the skin layer 63 in a direction intersecting the filler 13 extending along the outer surface 62 of the base portion 61.

When the carbonized portion 15 and the filler 13 intersect in this way, one end of the filler 13 tends to enter the base portion 61 and the carbonized portion 15 tends to be caught on the other end, so that the filler 13 tends to be caught in the carbonized portion 15. At the same time, it is possible to prevent the base portion 61 from being separated from the base portion 61.

Further, the filler 13 penetrates the carbide 66 in the carbonized portion 15. Thereby, the falling off of the carbonized portion 15 can be effectively suppressed.

Next, the resin member 10 will be described with reference to FIGS. 62 to 63. As shown in FIGS. 62 and 63, the carbonized portions 15 of the present embodiment are formed in a grid pattern.

The outer surface 62 of the base portion 61 is provided with a deformation mark 85 so as to extend along the peripheral edge portion of the carbonized portion 15. The deformation mark 85 is a mark where a part of the base portion 61 is deformed. Specifically, the deformation mark 85 is a melt-solidification mark that is melted and solidified. In another embodiment, the deformation mark 85 may be a removal mark by, for example, laser processing, machining such as polishing, or dissolution processing using a solution. Even if foreign matter such as scattered matter generated by the formation of the carbonized portion 15 adheres to the base portion 61, it is possible to remove the foreign matter from the base portion 61 when forming the deformation mark 85. Therefore, by providing the deformation mark 85, it is possible to prevent the design of the base portion 61 from being deteriorated due to the foreign matter.

The deformation mark 85 has a foamed portion 86 in which at least a part of the base portion 61 is foamed, and a plurality of point-shaped recesses 87 provided on the outer surface 62 of the base portion 61. These foamed portions 86 and point-shaped recesses 87 are deformation marks 85 that can be formed by heating the base portion 61. As shown in FIG. 13, the method for manufacturing the resin member 10 includes a preparation step S100, a first heating step S200, and a second heating step S300. In the second heating step S300, after the first heating step S200, at least a part of the base portion 61 is deformed so that the deformation mark 85 extends along the peripheral edge portion of the carbonized portion 15 on the outer surface 62 of the base portion 61. In the second heating step S300, the base portion 61 and the temperature are lower than the heating of the base portion 61 in the first heating step S200 so that the deformation mark 85 is formed on the outer surface 62 of the base portion 61. At least a part of each of the carbonized portions 15 is heated.

Here, when the foreign matter generated by the heating in the first heating step S200 remains attached to the outer surface 62 of the base portion 61, there is a concern that the charge release by the carbonized portion 15 is likely to be hindered by the foreign matter. To.

On the other hand, in the present embodiment, the foreign matter adhering to the base portion 61 can be removed by combustion or the like by heating in the second heating step S300.

Here, when the carbonized portion 15 includes a portion that is barely attached to the base portion 61 in an unstable posture, the posture of this portion changes, so that the charge can easily pass through the carbonized portion 15. It will change. In this case, there is a concern that the conductivity of the carbonized portion 15 changes depending on the posture of this portion, and the conductivity becomes unstable.

On the other hand, in the present embodiment, not only the base portion 61 but also a part of the carbonized portion 15 is removed when the deformation mark 85 is formed. At this time, the portion of the carbonized portion 15 having an unstable posture is more likely to be removed than the portion having a stable posture. That is, in the second heating step S300, not only the base portion 61 but also the carbonized portion 15 is heated, so that the portion of the carbonized portion 15 having an unstable posture can be removed by heating or burning. Therefore, it is possible to suppress the change in the conductivity of the carbonized portion 15 and stabilize the conductivity of the carbonized portion 15.

Further, the resistance value of the carbonized portion 15 can be controlled to a predetermined value by trimming to remove a part of the carbonized portion 15.

In the first heating step S200, the base portion 61 is heated by irradiating the base portion 61 with an electromagnetic wave such as a laser beam to form the carbonized portion 15. In the second heating step S300, the intensity (that is, output) is lower than the electromagnetic wave radiated to the base portion 61 in the first heating step S200, the scanning speed is increased, and the frequency is lowered. The base portion 61 is irradiated with electromagnetic waves. In the second heating step S300, the base portion 61 is heated by irradiating the electromagnetic wave in this way to form a deformation mark 85.

Since both the carbonized portion 15 and the deformation mark 85 can be formed by electromagnetic wave irradiation in this way, the work load when forming the carbonized portion 15 and the deformation mark 85 can be reduced. For example, if the first heating step S200 and the second heating step S300 are continuously performed, the work of aligning the base portion 61 with respect to the device that irradiates the electromagnetic wave can be summarized at one time. ..

When a laser is used to form the deformation mark 85, the resin may foam and discolor depending on the energy of the laser, but this can be intentionally generated for the purpose of imparting design. When a laser is used to form the deformation mark 85, it is desirable to use a pulse laser because it is suitable for removal processing. By using a pulse laser, the point-shaped recess 87 can be formed periodically.

As described above, the air flow meter 20 of the present embodiment includes a resin bypass housing 24 that has an insulating property and forms a bypass passage 30 through which a fluid flows. Further, the air flow meter 20 includes a flow rate detecting unit 22 that outputs a detection signal according to the physical quantity of the fluid flowing through the bypass passage 30. Further, the air flow meter 20 includes a conductive portion 90 having conductivity formed on the entire surface of the outer wall surface 24b of the bypass housing 24. The air flow meter 20 is configured such that an electric charge is discharged from the conductive portion 90 to the ground 45.

According to such a configuration, the charge suppressing function of the housing 21 can be improved by retrofitting the conductive portion 90 to the housing 21 by heating or the like after the housing 21 is resin-molded. In this case, the housing 21 and the physical quantity detecting unit are less likely to be charged, so that the physical quantity measuring device can improve the measurement accuracy.

Further, the conductive portion 90 contains a carbide 66 formed by carbonization by heat on the surface of the bypass housing 24. In this way, the conductive portion 90 can be configured to include the carbide 66 formed by carbonization.

Further, the conductive portion 90 is formed on the entire outer wall surface 24b of the bypass housing 24. According to this, the entire outer wall surface 24b of the bypass housing 24 can be made conductive.

Further, the conductive portion 90 is composed of a grid-like pattern 901. According to this, the pattern 901 can be formed quickly.

Further, the interval between adjacent patterns 901 is longer than the depth of the pattern 901. As described above, it is preferable that the interval between adjacent patterns 901 is longer than the depth of the pattern 901.

Further, since the interval between the grid-like patterns 901 is larger than the depth of the grid-like pattern 901, the number of patterns 901 constituting the conductive portion 90 can be reduced. Therefore, the work load for forming the conductive portion 90 can be reduced, and the work cost can be reduced. Further, since the depth of the grid-like pattern 901 is shallower than the interval of the grid-like pattern 901, it is possible to prevent the strength from being lowered due to the conductive portion 90 being made too deep.

Further, the interval between adjacent patterns 901 is a distance at which electric charges can be moved from one of the adjacent patterns 901 to the other by electric discharge.

Further, the conductive portion 90 is connected to the ground 45. In this way, the conductive portion 90 can be configured to be connected to the ground 45. Further, the electric charge can be stably discharged from the conductive portion 90 to the ground 45.

Further, the air flow meter 20 includes an intake air temperature sensor 23 that detects the temperature of the fluid, and is arranged so that the ground terminal 23b of the intake air temperature sensor 23 is exposed on the outer surface of the bypass housing 24. Then, the electric charge is discharged from the conductive portion 90 to the ground 45 via the ground terminal 23b of the intake air temperature sensor 23.

In this way, the electric charge can be discharged from the conductive portion 90 to the ground 45 via the ground terminal 23b of the intake air temperature sensor 23 arranged so as to be exposed on the outer surface of the bypass housing 24.

Further, the method of manufacturing the air flow meter 20 of the present embodiment includes preparing a resin bypass housing 24 which has an insulating property and forms a bypass passage 30 through which a fluid flows. Further, this manufacturing method includes forming a conductive portion 90 having conductivity so as to spread in a plane on the surface of the outer wall surface 24b of the bypass housing 24 by carbonization by heat.

According to this, after the housing 21 is resin-molded, the electrification suppressing function of the housing 21 can be improved by retrofitting the conductive portion 90 to the housing 21 by heating or the like. In this case, the housing 21 and the physical quantity detecting unit are less likely to be charged, so that the physical quantity measuring device can improve the measurement accuracy.

Further, by forming the conductive portion 90 on the surface of the bypass housing 24 by carbonization by heat, the conductive portion 90 is formed on the surface of the outer wall surface 24b of the bypass housing 24.

Thereby, the conductive portion 90 can be formed on the surface of the outer wall surface 24b of the bypass housing 24.

Further, in this manufacturing method, after forming the conductive portion 90 on the surface of the bypass housing 24 by carbonization by heat, the floating particles adhering to the surface of the bypass housing 24 by heat weaker than heat are removed and the volume is low efficiency. Includes performing at least one of the adjustments. The "heat weaker than heat" means heat weaker than the heat forming the conductive portion 90.

This allows at least one of the removal of suspended particles and the adjustment of low volume efficiency.

Further, by forming the conductive portion 90 on the surface of the bypass housing 24 by carbonization by heat, the conductive portion 90 is formed at the first scanning speed. Further, by performing at least one of removing suspended particles adhering to the surface of the bypass housing 24 and adjusting the volume low efficiency by heat weaker than heat, floating at a second scanning speed faster than the first scanning speed. At least one of particle removal and volume inefficiency adjustment is performed.

In this way, by performing at least one of removing the suspended particles adhering to the surface of the bypass housing 24 by heat weaker than heat and adjusting the volume inefficiency, the second scanning speed is faster than the first scanning speed. It is preferable to carry it out at.

In the present embodiment, the grid-like pattern 901 is formed around the ground terminal 23b of the intake air temperature sensor 23 in the ring holding portion 25, but one surface or the other surface of the ring holding portion 25 is entirely covered. A grid pattern 901 may be formed.

(Second Embodiment)
The air flow meter 20 according to the second embodiment will be described with reference to FIGS. 16 to 18. In the air flow meter 20 of the first embodiment, a grid-like pattern 901 having conductivity is formed around the entire outer wall surface 24b which is the outer surface of the bypass housing 24 and the through hole 251 formed in the ring holding portion 25. Has been done.

On the other hand, in the air flow meter 20 of the present embodiment, a grid-like pattern 901 having conductivity is formed around the through hole 251 formed in the ring holding portion 25 and a part of the outer wall surface 24b of the bypass housing 24. Has been done.

Specifically, the conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 in the portion where the detection element 22b of the flow rate detection unit 22 is located. More specifically, the conductive portion 90 is formed on the outer peripheral surface of the bypass housing 24 in the portion where the detection element 22b of the flow rate detection unit 22 is located. In other words, it is located in the direction orthogonal to the axial core connecting the housing base end side and the housing tip side when viewed from the portion of the outer wall surface 24b of the bypass housing 24 where the detection element 22b of the flow rate detection unit 22 is located. A conductive portion 90 is formed at the portion.

Further, the area of the region where the conductive portion 90 is not formed on the outer wall surface 24b of the bypass housing 24 is larger than the area of the region where the conductive portion 90 is formed on the outer wall surface 24b of the bypass housing 24.

When the conductive portion 90 is formed on the entire outer wall surface 24b of the bypass housing 24 as in the air flow meter 20 of the first embodiment, the time required for forming the conductive portion 90 is long and the cost is high.

However, as described above, the conductive portion 90 of the air flow meter 20 of the present embodiment is formed on a part of the outer wall surface 24b of the bypass housing 24. Therefore, the time required for forming the conductive portion 90 can be shortened, and the cost can be reduced.

Further, in the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 at the portion where the detection element 22b of the flow rate detection unit 22 is located. According to this, the influence of foreign matter such as charged dust on the detection element 22b can be effectively suppressed.

Further, the area of the region where the conductive portion 90 is not formed on the outer wall surface 24b of the bypass housing 24 is larger than the area of the region where the conductive portion 90 is formed on the outer wall surface 24b of the bypass housing 24.

As a result, the area of the region where the conductive portion 90 is formed can be reduced, and the strength decrease of the bypass housing 24 due to the formation of the conductive portion 90 can be suppressed.

In addition to the configuration of the present embodiment described above, for example, the conductive portion 90 is formed on the outer wall surface 24b of the bypass housing 24 located on the front side and the back side of the detection element 22b, respectively, and the conductive portion 90 is provided in addition to these portions. It can also be prevented from forming. That is, the detection element 22b may be arranged between the conductive portion 90 formed on one surface of the bypass housing 24 and the conductive portion 90 formed on the other surface of the bypass housing 24.

(Third Embodiment)
The air flow meter 20 according to the third embodiment will be described with reference to FIGS. 19 to 21. Also in the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the outer wall surface 24b which is the outer surface of the bypass housing 24. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 at the portion where the detection element 22b of the flow rate detection unit 22 and the introduction path 32b of the measurement passage 32 are located.

The air flow meter 20 has a detection element 22b that detects a physical quantity of air flowing through the bypass passage 30. Further, the bypass passage 30 has an introduction path 32b for introducing intake air into the detection path 32a in which the detection element 22b is arranged. The conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 so as to surround the detection element 22b and the introduction path 32b.

As described above, the air flow meter 20 is formed on a part of the outer wall surface 24b of the bypass housing 24. Therefore, the time required for forming the conductive portion 90 can be shortened, and the cost can be reduced.

Further, the conductive portion 90 of the air flow meter 20 of the present embodiment is formed on a part of the outer wall surface 24b of the bypass housing 24 so as to surround the detection element 22b and the introduction path 32b. According to this, the influence of foreign matter such as charged dust on the detection element 22b can be effectively suppressed.

In addition to the configuration of the present embodiment described above, for example, the conductive portion 90 is formed on the outer wall surface 24b of the bypass housing 24 located on the front side and the back side of the detection element 22b, respectively, and the conductive portion 90 is provided in addition to these portions. It can also be prevented from forming. That is, the detection element 22b may be arranged between the conductive portion 90 formed on one surface of the bypass housing 24 and the conductive portion 90 formed on the other surface of the bypass housing 24.

(Fourth Embodiment)
The air flow meter 20 according to the fourth embodiment will be described with reference to FIGS. 22 to 24. Also in the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the wall surface 24b which is the outer surface of the bypass housing 24. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the outer wall surface 24b which is the outer surface of the bypass housing 24 at the portion where the discharge path 32c of the bypass passage 30 is located.

In the air flow meter 20 of the present embodiment, the bypass passage 30 has an discharge path 32c for discharging air from the detection path 32a in which the detection element 22b is arranged. The conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 at the portion where the discharge passage 32c of the bypass passage 30 is located.

As described above, the conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24. Therefore, the time required for forming the conductive portion 90 can be shortened, and the cost can be reduced.

(Fifth Embodiment)
The air flow meter 20 according to the fifth embodiment will be described with reference to FIGS. 25 to 27. Also in the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the outer wall surface 24b which is the outer surface of the bypass housing 24. The air flow meter 20 of the present embodiment includes a detection path 32a in which the detection element 22b is arranged, and an introduction path 32b for introducing air into the detection path 32a. Further, a conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 at the portion where the passage passage 31 for introducing air into the introduction path 32b is located. That is, the conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24 at the portion where the bypass passage 30 on the upstream side of the air flow from the detection element 22b is located.

As described above, the conductive portion 90 is formed on a part of the outer wall surface 24b of the bypass housing 24. Therefore, the time required for forming the conductive portion 90 can be shortened, and the cost can be reduced.

(Sixth Embodiment)
The air flow meter 20 according to the sixth embodiment will be described with reference to FIGS. 28 to 30. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on the entire outer wall surface 24b which is the outer surface of the bypass housing 24. Further, a part of the conductive portion 90 of the air flow meter 20 of the present embodiment is formed of a grid-like pattern 901, and the remaining part of the conductive portion 90 is formed of a striped pattern 902.

The carbonized portion 15 shown in FIGS. 59 to 61 constitutes a plurality of conductive portions 902a shown in FIGS. 28 to 30. A plurality of carbonized portions 15 are formed so as to extend linearly. The plurality of conductive portions 902a are composed of carbonized portions 15 extending in an elongated shape. A plurality of linear conductive portions 902a extend in parallel to the outer surface 62 of the base portion 61.

The striped pattern 902 has a plurality of conductive portions 902a. Further, the plurality of conductive portions 902a extend in parallel.

In this way, the conductive portion 90 may be formed by combining the grid-like pattern 901 and the striped pattern 902.

(7th Embodiment)
The air flow meter 20 according to the seventh embodiment will be described with reference to FIGS. 31 to 34. In the air flow meter 20 of the present embodiment, a grid-like pattern 901 having conductivity is formed around the entire outer wall surface 24b which is the outer surface of the bypass housing 24 and the through hole 251 formed in the ring holding portion 25. There is.

Further, the conductive portion 90 of the air flow meter 20 of the present embodiment is composed of a striped pattern 902. In this way, the conductive portion 90 may be formed only by the striped pattern 902.

(8th Embodiment)
The air flow meter 20 according to the eighth embodiment will be described with reference to FIGS. 35 to 36. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on the entire inner wall surface 24a which is the inner surface of the bypass passage 30 of the bypass housing 24. In the air flow meter 20 of the present embodiment, the conductive portion 90 is not formed around the outer wall surface 24b of the bypass housing 24 and the through hole 251 formed in the ring holding portion 25. Further, the conductive portion 90 has a lattice shape.

The air flow meter 20 of the present embodiment is provided with a connection terminal 28b between the conductive portion 90 and the connector terminal 28a. Then, the electric charge of the conductive portion 90 is discharged from the connection terminal 28b to the ground 45 through the connector terminal 28a.

As described above, in the air flow meter 20 of the present embodiment, since the conductive portion 90 is formed on the entire inner wall surface 24a of the bypass passage 30 of the bypass housing 24, the entire inner wall surface 24a of the bypass passage 30 of the bypass housing 24 is formed. Can be made conductive.

(9th Embodiment)
The air flow meter 20 according to the ninth embodiment will be described with reference to FIGS. 37 to 38. In the air flow meter 20 of the eighth embodiment, the conductive portion 90 is formed on the entire inner wall surface 24a of the bypass passage 30 of the bypass housing 24. On the other hand, in the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the inner wall surface 24a of the bypass passage 30 of the bypass housing 24. In the air flow meter 20 of the present embodiment, the conductive portion 90 is not formed on the outer wall surface 24b of the bypass housing 24. Further, the conductive portion 90 has a lattice shape.

In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on the inner wall surface 24a of the measurement passage 32 out of the inner wall surface 24a which is the inner surface of the bypass passage 30 of the bypass housing 24. Further, of the inner wall surface 24a of the bypass passage 30 of the bypass housing 24, the conductive portion 90 is not formed on the inner wall surface 24a of the passage passage 31.

As described above, in the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the inner wall surface 24a of the bypass passage 30 of the bypass housing 24. Therefore, the time required for forming the conductive portion 90 can be shortened, and the cost can be reduced.

(10th Embodiment)
The air flow meter 20 according to the tenth embodiment will be described with reference to FIGS. 39 to 40. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on the entire inner wall surface 24a of the bypass passage 30 of the bypass housing 24. Further, a part of the conductive portion 90 is composed of a grid-like pattern 901, and the remaining part of the conductive portion 90 is composed of a striped pattern 902.

In this way, the conductive portion 90 may be formed by combining the grid-like pattern 901 and the striped pattern 902.

(11th Embodiment)
The air flow meter 20 according to the eleventh embodiment will be described with reference to FIGS. 41 to 42. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on the entire inner wall surface 24a which is the inner surface of the bypass passage 30 of the bypass housing 24. Further, the conductive portion 90 is composed of a striped pattern 902.

In this way, the striped pattern 902 can be arranged on the entire inner wall surface 24a of the bypass passage 30 of the bypass housing 24 to form the conductive portion 90.

(12th Embodiment)
The air flow meter 20 according to the twelfth embodiment will be described with reference to FIGS. 43 to 46. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed around the entire outer wall surface 24b which is the outer surface of the bypass housing 24 and the through hole 251 formed in the ring holding portion 25. The conductive portion 90 of the present embodiment is composed of a plurality of patterns 903 having a circular shape. The plurality of patterns 903 are formed at physically separated positions and are not connected to each other. There is. In the conductive portion 90, the pattern 903 is not formed on the inner surface of the bypass housing 24.

When an electric charge is accumulated in a part of a plurality of patterns 903, the electric charge moves one after another between the plurality of patterns 903 by electric discharge. Then, it is discharged from the ground terminal 23b of the intake air temperature sensor 23 to the ground 45 through the connector terminal 28a.

(13th Embodiment)
The air flow meter 20 according to the thirteenth embodiment will be described with reference to FIGS. 47 to 48. In the air flow meter 20 of the present embodiment, the pattern 903 is formed on the entire inner wall surface 24a which is the inner surface of the bypass passage 30 of the bypass housing 24. The conductive portion 90 has a plurality of patterns 903 having a circular shape. The plurality of patterns 903 are formed at physically separated positions. In the conductive portion 90, the pattern 903 is not formed on the outer wall surface 24b, which is the outer surface of the bypass housing 24.

When an electric charge is accumulated in a part of a plurality of patterns 903, the electric charge moves one after another between the plurality of patterns 903 by electric discharge. Then, the pattern 903 is discharged to the ground 45 through the connection terminal 28b and the connector terminal 28a.

(14th Embodiment)
The air flow meter 20 according to the 14th embodiment will be described with reference to FIGS. 49 to 50. A part of the conductive portion 90 of the air flow meter 20 of the present embodiment is formed of a grid-like pattern 901, and the remaining part of the conductive portion 90 is formed of a parallel running pattern 906 running in parallel with each other.

The grid-like pattern 901 is formed on the base end side of the bypass housing 24, and the parallel running pattern 906 is from the grid-like pattern 901 formed on the base end side of the housing toward the outlet 33b of the bypass housing 24. It is formed to extend.

In this way, the conductive portion 90 may be formed by combining the grid-like pattern 901 and the parallel running pattern 906.

(15th Embodiment)
The air flow meter 20 according to the fifteenth embodiment will be described with reference to FIGS. 51 to 52. In the air flow meter 20 of the present embodiment, the conductive portion 90 is formed on a part of the inner wall surface 24a which is the inner surface of the bypass housing 24. The conductive portion 90 is composed of a grid-like pattern 901, a parallel running pattern 906 running in parallel, and a curved curve pattern 907 forming a curved line.

The grid-like pattern 901 is formed on the inner wall surface 24a forming the measurement passage 32. The parallel running pattern 906 is formed so as to extend from the grid-like pattern 901 formed in the measurement passage 32 toward the outlet 33b of the bypass housing 24. The curved pattern 907 is formed so as to extend from the grid-like pattern 901 formed in the measuring passage 32 toward the passing passage 31 of the bypass housing 24.

In this way, the conductive portion 90 may be formed by combining the grid pattern 901, the parallel running pattern 906, and the curved pattern 907.

(16th Embodiment)
A method of manufacturing the air flow meter 20 according to the 16th embodiment will be described with reference to FIG. 53. In the present embodiment, as shown in FIGS. 35 to 36, an example in which the conductive portion 90 is formed on the entire inner wall surface 24a, which is the inner surface forming the bypass passage 30 of the bypass housing 24 of the air flow meter 20, will be described. As shown in FIG. 13, the method for manufacturing the air flow meter 20 of the present embodiment includes a preparation step, a first heating step, and a second heating step.

First, as shown in FIG. 53A, the operator prepares an air flow meter 20 including a resin bypass housing 24 that forms a bypass passage 30 through which a fluid flows in S100. The bypass housing 24 is prepared in a state of being divided by the dividing surface shown by the VI-VI line in FIG. Further, the intake air temperature sensor 23 is attached to the bypass housing 24 in advance. Then, one of the divided bypass housings 24 is fixed to the processing jig. In FIG. 53, the divided bypass housings are indicated by reference numerals 21A and 21B.

Next, as shown in FIG. 53 (b), the operator carries out the first heating step in S200. Specifically, the operator uses a laser machine to irradiate the surface of the bypass housing 24 with a laser in a grid pattern to heat the surface of the bypass housing 24. Here, laser irradiation is performed with high output.

Next, as shown in FIG. 53 (c), the worker carries out a second heating step called fume processing in S300. Specifically, the operator uses a laser machine to irradiate the entire surface of the bypass housing 24 with a laser at a higher speed to heat the surface of the bypass housing 24. Here, the laser irradiation is performed with a weaker output than the previous first heating step. As a result, dust or the like called fume generated when the laser irradiation is performed in the grid pattern is removed. Further, the volume resistivity of the conductive portion 90 is adjusted to a desired value.

Next, the other divided bypass housing 24 is fixed to the processing jig, and the first heating step of S200 and the second heating step of S300 are performed on the bypass housing 24.

Next, as shown in FIG. 53 (d), the operator integrates the divided one bypass housing 24 and the other bypass housing 24. In this way, the air flow meter 20 is completed.

As described above, when the conductive portion 90 is formed on the entire inner wall surface 24a forming the bypass passage 30 of the bypass housing 24 of the air flow meter 20, the bypass housing 24 is divided into a plurality of parts to form the conductive portion 90. .. After that, the conductive portion 90 can be formed on the inner wall surface 24a of the bypass housing 24 by integrating the plurality of divided bypass housings 24.

(17th Embodiment)
The air flow meter 20 according to the 17th embodiment will be described with reference to FIGS. 54A and 54B. The conductive portion 90 of the air flow meter 20 of the twelfth to fourteenth embodiments is composed of a plurality of patterns 903 having a circular shape.

As shown in FIG. 54A, the plurality of patterns 903 can be arranged so that the centers of the patterns 903 are arranged diagonally with respect to the longitudinal direction of the bypass housing 24. Further, as shown in FIG. 54B, the center of the pattern 903 may be arranged so as to be aligned in the vertical direction or the horizontal direction with respect to the longitudinal direction of the bypass housing 24.

(18th Embodiment)
The air flow meter 20 according to the eighteenth embodiment will be described with reference to FIGS. 55A and 55B. The conductive portion 90 of the air flow meter 20 of the present embodiment is composed of a plurality of patterns 904 forming a square.

As shown in FIG. 55A, the plurality of patterns 903 can be arranged so that the centers of the patterns 904 are aligned obliquely with respect to the longitudinal direction of the bypass housing 24. Further, as shown in FIG. 55B, the center of the pattern 904 may be arranged so as to be aligned in the vertical direction or the horizontal direction with respect to the longitudinal direction of the bypass housing 24.

(19th Embodiment)
The air flow meter 20 according to the 19th embodiment will be described with reference to FIGS. 56A and 56B. The conductive portion 90 of the air flow meter 20 of the present embodiment is composed of a plurality of patterns 905 forming a triangle.

As shown in FIG. 56A, the plurality of patterns 905 can be arranged so that the centers of the patterns 905 are aligned obliquely with respect to the longitudinal direction of the bypass housing 24. Further, as shown in FIG. 56B, the center of the pattern 905 may be arranged so as to be aligned in the vertical direction or the horizontal direction with respect to the longitudinal direction of the bypass housing 24.

(20th Embodiment)
The air flow meter 20 according to the twentieth embodiment will be described with reference to FIGS. 57A and 57B. The conductive portion 90 of the air flow meter 20 of the present embodiment is composed of a plurality of patterns 905 forming an inverted triangle with a triangle.

As shown in FIG. 57A, the plurality of patterns 905 can be arranged so that the centers of the patterns 905 are aligned obliquely with respect to the longitudinal direction of the bypass housing 24. Further, as shown in FIG. 57B, the center of the pattern 905 may be arranged so as to be aligned in the vertical direction or the horizontal direction with respect to the longitudinal direction of the bypass housing 24.

(21st Embodiment)
The air flow meter 20 according to the 21st embodiment will be described with reference to FIG. 58. The bypass housing 24 of the present embodiment has a first surface 241 and a second surface 242 extending in a direction intersecting the first surface 241 and a third surface 243 extending in a direction intersecting the second surface 242. ing.

Further, the bypass housing 24 loosely connects the connecting surface 244 that loosely connects the portion connecting the first surface 241 and the second surface 242 and the portion connecting the second surface 242 and the third surface 243. It has a connection surface 245 and.

The conductive portion 90 is formed so as to gently bend from the first surface 241 to the third surface 243 via the connecting surface 244, the second surface 242, and the connecting surface 245.

As the shape of the molded body before forming the conductive portion 90, it is desirable that the molten resin flows at the portion to be carbonized as much as possible during molding. Therefore, the connecting surface 244 between the first surface 241 and the second surface 242 and the connecting surface 245 between the second surface 242 and the third surface 243 have a relatively large R shape (that is, a round shape). There is. It is desirable that the radius of curvature of the corner portion 34 and the corner portion 35 be as large as possible, and the specific size is preferably at least 5 mm or more.

Further, the processing accuracy of the conductive portion 90 can be improved by forming the connecting surface 244 and the connecting surface 245 into a relatively large R shape.

(Other embodiments)
(1) In each of the above embodiments, the electric charges of the patterns 901 to 906 constituting the conductive portion 90 are discharged to the ground 45 via the ground terminal 23b of the intake air temperature sensor 23 or the connection terminal 28b. However, the electric charges of the patterns 901 to 906 constituting the conductive portion 90 may be discharged to the ground 45 from a portion other than the ground terminal 23b and the connection terminal 28b of the intake air temperature sensor 23.

(2) In each of the above embodiments, the patterns 901 to 906 constituting the conductive portion 90 are electrically connected to the ground terminal 23b or the connection terminal 28b of the intake air temperature sensor 23.

On the other hand, the conductive portion 90 and the ground terminal 23b of the intake air temperature sensor 23 may not be connected. Specifically, a gap may be provided between the conductive portion 90 and the ground terminal 23b or the connection terminal 28b of the intake air temperature sensor 23, and the conductive portion 90 and the ground 45 may not be connected. However, in this case, the separation distance between the conductive portion 90 and the ground terminal 23b or the connection terminal 28b of the intake air temperature sensor 23 is the distance at which the electric charge can move from the conductive portion 90 to the ground 45.

Even in such a case, the electric charge can be transferred from the conductive portion 90 to the ground terminal 23b or the connection terminal 28b of the intake air temperature sensor 23 by the electric discharge, and then discharged to the ground 45 through the connector terminal 28a. The distance between the conductive portion 90 and the ground terminal 23b or the connection terminal 28b of the intake air temperature sensor 23 is preferably less than 0.5 mm.

In this way, when the conductive portion 90 and the ground terminal 23b of the intake air temperature sensor 23 are not connected, it is not necessary to apply the laser to the ground terminal 23b of the intake air temperature sensor 23. Deformation and alteration of 23b can be suppressed.

(3) In each of the above embodiments, the conductive portion 90 is formed by laser irradiation, but the present invention is not limited to this, and other methods such as plasma treatment, high-pressure steam irradiation, electron beam irradiation, and heating using Joule heat are used. Also, the optimum method can be selected according to the workability of the resin member 10.

(4) The ground connection portion that connects the conductive portion 90 and the ground 45 is not limited to the intake air temperature terminal, and may be another portion such as an intake pipe. In short, the ground connection portion may be connected to the ground 45 and can discharge the electric charge to the ground 45.

(5) The conductive portion 90 is not limited to the pattern shape, but may be formed into a film shape. In this case, better electromagnetic wave shielding properties can be imparted to the resin member 10.

(6) The conductive portion 90 is not limited to the one containing the carbide 66 formed by carbonization by heat. For example, a metal pattern may be formed on the surface of the housing 21 as the conductive portion 90 having conductivity.

(7) In the first embodiment, the first conductive portion 901a and the second conductive portion 901b are formed in a + shape, but can be formed so as to be connected in a T shape, for example. Further, the first conductive portion 901a and the second conductive portion 901b do not have to be orthogonal to each other. Further, at least one of the first conductive portion 901a and the second conductive portion 901b may be formed. Further, either the first conductive portion 901a or the second conductive portion 901b may be connected to the ground 45, or both the first conductive portion 901a and the second conductive portion 901b may be connected to the ground 45. .. Further, either the first conductive portion 901a or the second conductive portion 901b may be arranged so as to be close to the ground 45 without being connected to the ground 45. Further, the first conductive portion 901a and the second conductive portion 901b do not have to extend linearly, and may have a curved shape, for example. Further, the first conductive portion 901a and the second conductive portion 901b may be arranged apart from each other. However, in this case, it is preferable to set the separation distance so that the electric charge can move.

(8) In the twelfth to thirteenth embodiments, the plurality of patterns 903 are arranged apart from each other and are not connected to each other. Part or all of the portions may be connected by a second conductive portion (not shown).

(9) In the sixth to seventh and tenth to eleventh embodiments described above, all or part of the conductive portion 90 is composed of a striped pattern 902. These striped patterns 902 may be formed so as to extend in any of the vertical direction, the horizontal direction, and the oblique direction with respect to the housing 21.

Note that the present disclosure is not limited to the above-described embodiment, and can be changed as appropriate. Further, the above-described embodiments are not unrelated to each other, and can be appropriately combined unless the combination is clearly impossible. Further, in each of the above embodiments, it goes without saying that the elements constituting the embodiment are not necessarily essential except when it is clearly stated that they are essential and when they are clearly considered to be essential in principle. No. Further, in each of the above embodiments, when numerical values such as the number, numerical values, amounts, and ranges of the constituent elements of the embodiment are mentioned, when it is clearly stated that they are particularly essential, and in principle, the number is clearly limited to a specific number. It is not limited to the specific number except when it is done. Further, in each of the above embodiments, when referring to the material, shape, positional relationship, etc. of the constituent elements, etc., except when specifically specified or when the material, shape, positional relationship, etc. are limited in principle. , The material, shape, positional relationship, etc. are not limited.

(Summary)
According to the first aspect shown in a part or all of the above-described embodiments, the physical quantity measuring device for measuring the physical quantity of the fluid has an insulating property and is a resin bypass forming a bypass passage through which the fluid flows. It has a housing. Further, the physical quantity measuring device includes a physical quantity detecting unit that outputs a detection signal according to the physical quantity of the fluid flowing through the bypass passage. Further, the physical quantity measuring device includes a conductive portion having conductivity formed on at least one surface of the outer surface of the bypass housing and the inner surface of the bypass housing forming the bypass passage. The physical quantity measuring device is configured such that an electric charge is discharged from the conductive portion to the ground.

Further, according to the second aspect, the conductive portion contains a carbide formed by carbonization by heat on the surface of the bypass housing. In this way, the conductive portion can be configured to contain the carbonized material formed by carbonization.

Further, according to the third viewpoint, the conductive portion is formed on the entire outer surface of the bypass housing. According to this, the entire outer surface of the bypass housing can be made conductive.

Further, according to the fourth viewpoint, the conductive portion is formed on a part of the outer surface of the bypass housing. According to this, since the area of the conductive portion can be reduced as compared with the case where the conductive portion is formed on the entire outer surface of the bypass housing, the conductive portion can be formed in a short time and the manufacturing cost is reduced. You can also do it.

Further, according to the fifth viewpoint, the physical quantity detecting unit has a detection element for detecting the physical quantity of the fluid flowing through the bypass passage. The conductive portion is formed on a part of the outer surface of the bypass housing so as to surround the periphery of the detection element.

In this way, it is possible to reduce the influence of foreign matter such as charged dust on the detection element without forming a conductive portion on the entire outer surface of the bypass housing.

Further, according to the sixth aspect, the physical quantity detection unit has a detection element for detecting the physical quantity of the fluid flowing through the bypass passage, and the bypass passage introduces the intake air into the detection path in which the detection element is arranged. Has a road. Then, a conductive portion is arranged on a part of the outer surface of the bypass housing so as to surround the detection element and the introduction path.

In this way, it is possible to reduce the influence of foreign matter such as charged dust on the detection element without forming a conductive portion on the entire outer surface of the bypass housing.

Further, according to the seventh viewpoint, the conductive portion is formed on the entire inner surface forming the bypass passage. In this way, even if the conductive portion is formed on the entire inner surface forming the bypass passage, it is possible to reduce the influence of foreign matter such as charged dust on the physical quantity detecting portion.

Further, according to the eighth viewpoint, the conductive portion is formed on a part of the inner surface of the bypass housing forming the bypass passage.

Therefore, the area of the conductive portion can be reduced as compared with the case where the conductive portion is formed on the entire inner surface of the bypass housing forming the bypass passage, so that the conductive portion can be formed in a short time and the manufacturing cost is reduced. It can also be reduced.

Further, according to the ninth viewpoint, the conductive portion is composed of a grid-like pattern. According to this, the pattern can be formed quickly.

Further, according to the tenth viewpoint, the conductive portion is composed of a striped pattern. According to this, the pattern can be formed more quickly.

Also, according to the eleventh viewpoint, the interval between adjacent patterns is longer than the depth of the pattern. As described above, it is preferable that the interval between adjacent patterns is longer than the depth of the pattern.

Further, according to the twelfth viewpoint, the bypass housing loosely connects the first surface, the second surface extending in the direction intersecting the first surface, and the portion connecting the first surface and the second surface. It has a connecting surface. The conductive portion is formed in a path from the first surface to the second surface via the connecting surface.

According to such a configuration, since the portion connecting the first surface and the second surface is loosely connected, it is possible to easily process the conductive portion on the connecting surface.

Further, according to the thirteenth viewpoint, the conductive portion is composed of a plurality of patterns forming a circular shape or a polygonal shape. Further, a plurality of patterns are formed so as to spread in a plane on the surface of the bypass housing, and electric charges are released to the ground by the discharge generated between the plurality of patterns.

In this way, the conductive portion can be configured by a plurality of patterns forming a circular shape or a polygonal shape, and the electric charge can be discharged to the ground by the discharge generated between the plurality of patterns.

Further, according to the fourteenth viewpoint, the interval between adjacent patterns is a distance at which electric charges can be moved from one of the adjacent patterns to the other by electric discharge.

In this way, the distance between adjacent patterns can be a distance at which charges can move from one of the adjacent patterns to the other by electric discharge.

Further, according to the fifteenth viewpoint, the conductive portion is connected to the ground. In this way, the conductive portion can be configured to be connected to the ground.

Further, according to the 16th viewpoint, the conductive portion is not connected to the ground, and the electric charge is discharged from the conductive portion to the ground by the electric discharge. In this way, the conductive portion can be not connected to the ground, and the electric charge can be discharged from the conductive portion to the ground by electric discharge.

Further, according to the 17th viewpoint, the physical quantity measuring device includes a temperature sensor that detects the temperature of the fluid. Further, the ground terminal of the temperature sensor is arranged so as to be exposed on the outer surface of the bypass housing, and the electric charge is discharged from the conductive portion to the ground via the ground terminal of the temperature sensor.

In this way, the electric charge can be discharged from the conductive portion to the ground via the ground terminal of the temperature sensor arranged so as to be exposed on the outer surface of the bypass housing.

Further, according to the eighteenth viewpoint, the area of the region where the conductive portion is not formed on the outer surface of the bypass housing is larger than the area of the region where the conductive portion is formed on the outer surface of the bypass housing.

As a result, the area of the region where the conductive portion is formed can be reduced, and the decrease in strength of the bypass housing due to the formation of the conductive portion can be suppressed.

Further, according to the nineteenth viewpoint, the conductive portion is formed on the surface of only one of the outer surface of the bypass housing and the inner surface of the bypass housing. Further, the wall thickness between one surface of the bypass housing in which the conductive portion is formed and the other surface of the bypass housing is insulated between one surface in which the conductive portion of the bypass housing is formed and the other surface. The length is such that it can be discharged by breakdown.

According to this, it is possible to generate an electric discharge due to dielectric breakdown between one surface on which the conductive portion of the bypass housing is formed and the other surface.

Further, according to the twentieth viewpoint, the method for manufacturing the physical quantity detecting device of the present embodiment includes preparing a resin bypass housing having insulating properties and forming a bypass passage through which a fluid flows. Further, this manufacturing method includes forming a conductive portion having conductivity on at least one of an outer surface of the bypass housing and an inner surface forming the bypass passage by carbonization by heat.

Further, according to the 21st viewpoint, by forming the conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by heat, the conductive portion is formed on the outer surface of the bypass housing. Thereby, the conductive portion can be formed on the outer surface of the bypass housing.

Further, according to the 22nd viewpoint, by forming the conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by heat, the conductive portion is formed on the inner surface of the bypass housing. Thereby, the conductive portion can be formed on the inner surface of the bypass housing.

Further, according to the 23rd aspect, after forming a conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by heat, it adheres to at least one of the outer surface and the inner surface of the bypass housing by heat weaker than heat. Includes performing at least one of the removal of suspended particles and the adjustment of low volume efficiency.

This allows at least one of the removal of suspended particles and the adjustment of low volume efficiency.

Further, according to the 24th viewpoint, by forming the conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by heat, the conductive portion is formed at the first scanning speed. Further, by performing at least one of removing suspended particles adhering to at least one of the outer surface and the inner surface of the bypass housing by heat weaker than heat and adjusting the volume inefficiency, the second scanning speed is faster than the first scanning speed. At least one of the removal of suspended particles and the adjustment of low volume efficiency is performed at the scanning speed.

Thus, by performing at least one of removing suspended particles adhering to the surface of the bypass housing and adjusting the volume inefficiency by heat weaker than heat, the second scanning speed is faster than the first scanning speed. It is preferable to carry it out.

Claims (24)

1. A physical quantity measuring device (20) that measures a physical quantity of a fluid.
   A resin bypass housing (24) having an insulating property and forming a bypass passage (30) through which the fluid flows,
   A physical quantity detection unit (22) that outputs a detection signal according to the physical quantity of the fluid flowing through the bypass passage, and a physical quantity detection unit (22).
   A conductive portion (90) formed on at least one of an outer surface (24b) of the bypass housing and an inner surface (24a) of the bypass housing forming the bypass passage is provided.
   A physical quantity measuring device in which an electric charge is discharged from the conductive portion to the ground (45).
2. The physical quantity measuring device according to claim 1, wherein the conductive portion contains carbides formed by carbonization by heat on the surface of the bypass housing.
3. The physical quantity measuring device according to claim 1 or 2, wherein the conductive portion is formed on the entire outer surface of the bypass housing.
4. The physical quantity measuring device according to claim 1 or 2, wherein the conductive portion is formed on a part of the outer surface of the bypass housing.
5. The physical quantity detecting unit has a detection element (22b) for detecting the physical quantity of the fluid.
   The physical quantity measuring device according to claim 4, wherein the conductive portion is formed on a part of the outer surface of the bypass housing so as to surround the detection element.
6. The physical quantity detecting unit has a detection element (22b) for detecting the physical quantity of the fluid flowing through the bypass passage.
   The bypass passage has an introduction path (32b) for introducing intake air into the detection path (32a) in which the detection element is arranged.
   The physical quantity measuring device according to claim 4, wherein the conductive portion is formed on a part of the outer surface of the bypass housing so as to surround the detection element and the introduction path.
7. The physical quantity measuring device according to any one of claims 1 to 6, wherein the conductive portion is formed on the entire inner surface forming the bypass passage.
8. The physical quantity measuring device according to any one of claims 1 to 6, wherein the conductive portion is formed on a part of the inner surface of the bypass housing forming the bypass passage.
9. The physical quantity measuring device according to any one of claims 1 to 8, wherein the conductive portion is composed of a grid-like pattern (901).
10. The physical quantity measuring device according to any one of claims 1 to 8, wherein the conductive portion is composed of a striped pattern (902).
11. The physical quantity measuring device according to claim 9 or 10, wherein the interval between adjacent patterns is longer than the depth of the pattern.
12. The bypass housing loosely connects a first surface (241), a second surface (242) extending in a direction intersecting the first surface, and a portion connecting the first surface and the second surface. Has a connecting surface (244) and
    The physical quantity measuring device according to any one of claims 1 to 11, wherein the conductive portion is formed in a path from the first surface to the second surface via the connecting surface.
13. The conductive portion is composed of a plurality of patterns (903 to 905) forming a circular shape or a polygonal shape.
    The plurality of patterns are formed so as to spread in a plane on the surface of the bypass housing.
    The physical quantity measuring device according to any one of claims 1 to 12, wherein the electric charge is discharged to the ground by a discharge generated between the plurality of patterns.
14. The physical quantity measuring device according to claim 11, wherein the interval between adjacent patterns is a distance at which electric charges can be moved from one of the adjacent patterns to the other by electric discharge.
15. The physical quantity measuring device according to any one of claims 1 to 14, wherein the conductive portion is connected to the ground (45).
16. The conductive portion is not connected to the ground and is not connected.
    The physical quantity measuring device according to any one of claims 1 to 14, wherein an electric charge is discharged from the conductive portion to the ground by electric discharge.
17. A temperature sensor (23) for detecting the temperature of the fluid is provided.
    The ground terminal of the temperature sensor is arranged so as to be exposed on the outer surface of the bypass housing.
    The physical quantity measuring device according to any one of claims 1 to 16, wherein an electric charge is discharged from the conductive portion to the ground (45) via the ground terminal of the temperature sensor.
18. The fourth aspect of the present invention, wherein the area of the region where the conductive portion is not formed on the outer surface of the bypass housing is larger than the area of the region where the conductive portion is formed on the outer surface of the bypass housing. Physical quantity measuring device.
19. The conductive portion is formed on the surface of only one of the outer surface of the bypass housing and the inner surface of the bypass housing.
    The wall thickness between the one surface of the bypass housing on which the conductive portion is formed and the other surface of the bypass housing is the thickness between the one surface on which the conductive portion of the bypass housing is formed and the other surface. The physical quantity measuring device according to claim 1 or 2, which has a length that allows discharge due to dielectric breakdown between the surface and the surface.
20. It is a manufacturing method of a physical quantity measuring device that measures the physical quantity of a fluid.
    To prepare a resin bypass housing (24) that has insulating properties and forms a bypass passage (30) through which the fluid flows.
    A method for manufacturing a physical quantity measuring device, comprising forming a conductive portion having conductivity on at least one of an outer surface (24b) of the bypass housing and an inner surface (24a) forming the bypass passage by carbonization by heat.
21. The method for manufacturing a physical quantity measuring device according to claim 20, wherein a conductive portion is formed on at least one of the outer surface and the inner surface of the bypass housing by carbonization by the heat to form a conductive portion on the outer surface of the bypass housing. ..
22. The physical quantity measuring device according to claim 20, wherein the conductive portion is formed on the inner surface of the bypass housing by forming the conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by the heat. Production method.
23. After forming the conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by the heat, the conductive portion was attached to at least one of the outer surface and the inner surface of the bypass housing by heat weaker than the heat. The method for manufacturing a physical quantity measuring device according to any one of claims 20 to 22, wherein at least one of removal of suspended particles and adjustment of low volume efficiency is performed.
24. By forming the conductive portion on at least one of the outer surface and the inner surface of the bypass housing by carbonization by the heat, the conductive portion is formed at the first scanning speed.
    By removing the suspended particles adhering to at least one of the outer surface and the inner surface of the bypass housing by heat weaker than the heat and adjusting the volume low efficiency, the scanning speed is higher than that of the first scanning speed. The method for manufacturing a physical quantity measuring device according to claim 23, wherein at least one of the removal of the suspended particles and the adjustment of the low volume efficiency is performed at a second scanning speed which is also fast.

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