阅读说明：本技术 流量测量装置 (Flow rate measuring device ) 是由 上之段晓 五来信章 广畑成人 齐藤直生 三木崇裕 于 2020-06-09 设计创作，主要内容包括：本发明的目的在于提高流量测量装置的测量精度。一种流量测量装置,其包括：第1空隙,其由支承体的一面和电路基板的一面形成；第2空隙,其由电路基板的一面的相反侧的面和所述壳体形成；和第3空隙,其由支承体的一面的相反侧的面和罩形成。(The invention aims to improve the measurement accuracy of a flow rate measurement device. A flow measurement device, comprising: a 1 st gap formed by one surface of the support and one surface of the circuit board; a 2 nd space formed by a surface opposite to the one surface of the circuit board and the case; and a 3 rd gap formed by a surface opposite to the one surface of the support and the cover.)

1. A flow measuring device including a housing, a cover, and a secondary passage formed by the housing and the cover together, the flow measuring device characterized by comprising:

a circuit board mounted on the housing, a part of which is disposed in the sub passage;

a support body mounted on the circuit board and having a part thereof disposed in the sub-passage; and

a flow rate measurement element attached to the support body and having a measurement surface arranged in the sub-passage,

the flow rate measurement element is disposed on one surface side of the support body such that a measurement surface of the flow rate measurement element faces one surface side of a portion of the circuit board disposed in the sub passage,

the flow rate measurement device further includes:

a 1 st void formed by one surface of the support body and one surface of the circuit board;

a 2 nd space formed by a surface of the circuit board opposite to the one surface and the case; and

and a 3 rd gap formed by a surface of the support body opposite to the one surface and the cover.

2. The flow measuring device of claim 1, wherein:

the 1 st void is disposed between the 2 nd and 3 rd voids.

3. The flow measuring device of claim 2, wherein:

the width of the 1 st gap in the thickness direction is smaller than the width of the 2 nd gap in the thickness direction,

the width of the 1 st gap in the thickness direction is larger than the width of the 3 rd gap in the thickness direction.

4. A flow measuring device according to claim 3, wherein:

the width of the portion of the support body disposed in the sub-passage is formed larger than the width of the portion of the circuit board disposed in the sub-passage,

the upstream end of the support body disposed in the sub-passage is located upstream of the upstream end of the circuit board disposed in the sub-passage.

5. The flow measuring device of claim 4, wherein:

the downstream end of the portion of the support body disposed in the sub-passage is located downstream of the downstream end of the portion of the circuit board disposed in the sub-passage.

6. The flow measuring device of claim 5, wherein:

a recess is formed in the cover and,

a flow measurement element is located within the recess.

7. The flow measuring device of claim 5, wherein:

a recess is formed in the cover and,

an upstream end of the support body is located in the recess.

8. The flow measuring device of claim 7, wherein:

the downstream end of the support body is located in the recess.

9. A flow measuring device according to claim 3, wherein:

a protrusion having an inclination is formed at the cover,

the measurement surface of the flow rate measurement element is disposed at a position shifted toward the cover side from the apex of the protrusion.

10. The flow measuring device of claim 2, wherein:

the width of the 1 st gap in the thickness direction is smaller than the width of the 2 nd gap in the thickness direction,

the width of the 1 st gap in the thickness direction is smaller than the width of the 3 rd gap in the thickness direction.

11. A flow rate measuring device according to any one of claims 1 to 10, wherein:

the support body is a resin package in which the flow rate measurement element is sealed with a resin,

the flow rate measurement device has a throttle shape formed to be tapered in a measurement plane direction of the flow rate measurement element.

12. A flow rate measuring device according to any one of claims 1 to 9, wherein:

and an adhesive is arranged in the No. 3 gap.

13. A method of manufacturing a flow rate measurement device, comprising:

a step of forming a 1 st gap by mounting the sensor element on the circuit board;

a step of forming a 2 nd gap by mounting the circuit substrate to the housing; and

a step of forming a 3 rd space by mounting the cover to the housing,

after performing both the 1 st and 2 nd steps, a 3 rd step is performed.

Technical Field

The present invention relates to a flow rate measurement device that measures a flow rate of a measurement target gas.

Background

As an example of the flow rate measurement device, the technique of patent document 1 is disclosed.

Documents of the prior art

Patent document

Patent document 1: WO2019/049513

Disclosure of Invention

Problems to be solved by the invention

In the flow rate measuring apparatus, a flow path (hereinafter referred to as D1) in which a measurement surface of the flow rate measuring element is arranged and a flow path (hereinafter referred to as D2) in which the measurement surface is not arranged are branched in the sub path. Patent document 1 has studied to reduce the dimensional variation of D1, but does not disclose the reduction of the dimensional variation of D2. As a result of intensive studies, the inventors of the present invention found that the measurement accuracy of the flow rate measurement device is affected by the splitting ratio between D1 and D2 in addition to the size of D1. In patent document 1, there is room for improvement in reducing the variation in the shunt ratio.

The invention aims to provide a high-precision flow rate measuring device.

Means for solving the problems

In order to achieve the above object, a flow rate measurement device of the present invention includes: a circuit board mounted on the housing, a part of which is disposed in the sub passage; a support body mounted on the circuit board, a part of which is arranged in the sub-passage; and a flow rate measurement element mounted on the support body, the measurement surface being disposed in the sub-passage, the flow rate measurement element being disposed on one surface side of the support body such that the measurement surface of the flow rate measurement element faces one surface side of a portion of the circuit board disposed in the sub-passage, the flow rate measurement device further including: a 1 st gap formed by one surface of the support and one surface of the circuit board; a 2 nd space formed by a surface opposite to the one surface of the circuit board and the case; and a 3 rd gap formed by a surface opposite to the one surface of the support and the cover.

Effects of the invention

According to the present invention, a high-precision flow rate measurement device can be provided.

Drawings

Fig. 1 is a plan view of a flow rate measurement device of embodiment 1 of the present invention.

Fig. 2 is a plan view of a flow rate measurement device according to embodiment 1 of the present invention before cover attachment.

Fig. 3 is a plan view of a circuit substrate and a sensor assembly in embodiment 1 of the invention.

Fig. 4 is a plan view of a sensor assembly in embodiment 1 of the invention.

Fig. 5 is a schematic view of the section a-a of fig. 2 in example 1 of the present invention.

Fig. 6 is a schematic view of the section B-B of fig. 2 in embodiment 1 of the present invention.

Fig. 7 is a plan view of a circuit substrate and a sensor assembly in embodiment 2 of the invention.

Fig. 8 is a schematic view of section B-B of fig. 2 in embodiment 2 of the present invention.

Fig. 9 is a schematic view of section B-B of fig. 2 in embodiment 3 of the present invention.

Fig. 10 is a schematic view of section B-B of fig. 2 in embodiment 4 of the present invention.

Fig. 11 is a schematic view of the section B-B of fig. 2 in the 5 th embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(example 1)

Embodiment 1 of the flow rate measuring apparatus will be described with reference to fig. 1 to 6.

As shown in fig. 1 and 2, the flow rate measurement device 1 in the present embodiment includes a housing 11 constituting a part of the sub passage 12, a cover 31, a circuit substrate 15 mounted on the housing 11, and a sensor assembly 10 mounted on the circuit substrate 15. The cover 31 and the housing 11 are fixed with an adhesive 17, for example. The housing 11 is formed with a sub-passage groove for constituting the sub-passage 12, and forms the sub-passage 12 for taking in a part of the air 30 as the medium to be measured by cooperating with the cover 31. The cover 31 may be formed with a sub-passage groove and the housing 11 may not be formed with a sub-passage groove, or both the cover 31 and the housing 11 may be formed with a sub-passage groove.

As shown in fig. 3, a circuit board assembly is configured such that the sensor assembly 10 is mounted on the circuit board 15. The sensor unit 10 having the flow rate detecting element 4 for measuring the flow rate of the gas is mounted on the circuit board 15. The sensor unit 10 is electrically connected to the circuit board 15 by, for example, soldering. In addition to the sensor unit 10, a pressure sensor 6, a humidity sensor 7, and the like may be mounted on the circuit board 15. By selecting the loading/unloading of the pressure sensor 6 and the humidity sensor 7 as needed, flow rate measuring devices of various configurations can be provided.

At least the detection portion of the flow rate detection element 4 in the sensor unit 10 is located in the sub-passage 12. The circuit board 15 is formed such that a part thereof is positioned in the sub-passage 12. The sensor unit 10 is mounted on the circuit board 15 such that the measurement portion of the flow rate detection element 4 faces the portion of the circuit board 15 located in the sub-passage 12.

As shown in fig. 4, the sensor unit 10 is a resin package sealed with resin so that at least the measurement portion of the flow rate detection element 4 is exposed. The flow rate detection element 4 is a semiconductor element formed by an MEMS process, and includes a thin portion (detection portion) forming a heating element. The sensor module 10 is a resin package in which the flow rate detection element 4, the LSI3, and the lead frame 5 are sealed with resin, and has a structure in which a part of the flow rate detection portion of the flow rate detection element 4 is exposed. The sensor unit 10 has a shape having a concave portion 14, and the measurement surface of the flow rate detection element 4 is located at the bottom of the concave portion. The concave portion has a throttle shape (throttle portion) that gradually tapers in the direction of the measurement surface as it goes from the end portion toward the flow rate measurement element. By forming the throttle shape with the resin sealing the flow rate measuring element, the positional relationship between the throttle portion and the measuring portion can be formed with high accuracy, and the measurement accuracy is improved, which is preferable. In addition, compared to the case of throttling in the direction perpendicular to the measurement surface, the amount of air containing contaminants guided to the measurement surface is reduced by throttling in the direction parallel to the measurement surface, and therefore the stain resistance is also excellent. Further, the LSI and the flow rate detection element 4 may be integrated, or the LSI may be fixed to the circuit board 15. The sensor unit 10 may be configured such that the flow rate measurement element 4 is mounted on a resin molded body (sensor support body) in which the metal terminals are sealed with resin. The sensor assembly 10 is a support body including at least the flow rate detecting element 4 and a member supporting the flow rate detecting element.

As shown in fig. 5 and 6, a 1 st gap 32 is formed by one surface of the circuit board 15 located in the sub-passage 12 and one surface of the sensor unit 10 located on the measurement portion side of the flow rate measurement element 4, a 2 nd gap 33 is formed by the other surface of the circuit board 15 located in the sub-passage 12 and the case 11, and a 3 rd gap 34 is formed by the other surface of the sensor unit 10 and the cover 31.

The sensor module 10 is mounted on the circuit board 15, and first, the 1 st void 32 is formed. Thereafter, the circuit board 15 having the sensor module 10 mounted thereon is mounted on the housing 11 to form the 2 nd gap 33. Finally, the cover 31 is attached to the housing 11, thereby forming the 3 rd space 34. Further, the 1 st gap 32 may be formed by mounting the sensor unit 10 on the circuit board 15 after the 2 nd gap 33 is formed by mounting the circuit board 15 on the case 11. That is, in the present embodiment, after both the 1 st and 2 nd voids 32 and 33 are formed, the 3 rd void 34 is formed.

The fluid flowing through the sub-passage 12 is divided into a flow path D1 having a measurement surface and a flow path D2 having no measurement surface by the circuit board 15. The 1 st void corresponds to D1 and the 2 nd void corresponds to D2.

The dimensional variation in the thickness direction of the 1 st void 32 is affected by the thickness variation of the sensor module 10 and the fixing member such as solder for fixing the sensor module 10 to the circuit board.

The dimensional variation in the thickness direction of the 2 nd gap 33 is affected by the thickness variation of the case 11 and the adhesive 17 for fixing the circuit board to the case.

The dimensional variation in the thickness direction of the 3 rd gap 34 is affected by the thickness variation of the case 11, the adhesive 17 for fixing the circuit board to the case, the circuit board 15, the sensor module 10, the fixing member such as solder for fixing the sensor module 10 to the circuit board, and the adhesive 17 for bonding the cover 31 and the case 11.

By mounting the sensor unit 10 on the circuit board 15 so that the flow rate measurement element 4 faces the circuit board 15, variations in the thickness of the circuit board 15 do not affect variations in the thickness direction of the 1 st gap 32. By bonding the case 11 to the other surface of the circuit board, variations in the thickness of the circuit board 15 and variations in the thickness of the sensor unit 10 do not affect variations in the thickness direction of the 2 nd gap 33.

Further, by forming the 3 rd gap 34 after forming both the 1 st gap 32 and the 2 nd gap 33 (in other words, the 3 rd gap 33 is located on the upper side in the stacking direction than the 1 st gap 32 and the 2 nd gap 33, that is, the 1 st gap 32 is located between the 2 nd gap 33 and the 3 rd gap 34), it is possible to concentrate the stacking tolerance variation in the 3 rd gap 34. The 3 rd space 34 formed between the sensor unit 10 and the cover 31 may be filled with an adhesive or the like. Since the 3 rd gap 34 is filled, the inflow of air into the 3 rd gap can be suppressed, and the influence of the fluid by the 3 rd gap can be suppressed.

In the present embodiment, the 3 rd gap is formed in addition to the 1 st gap and the 2 nd gap, and the dimensional deviation of each member is concentrated in the 3 rd gap, whereby the dimensional deviation of D1 and D2 can be reduced, the D1 size and the flow dividing ratio of D1 to D2 can be formed with high accuracy, and thus a high-accuracy flow rate measurement device can be provided.

As a further preferable example, the 3 rd gap 34 is smaller than the 1 st gap 32 and the 2 nd gap 33. By reducing the amount of air flowing into the 3 rd gap, the influence of the 3 rd gap on the flow of the fluid can be suppressed. More preferably, the 1 st void 32 is smaller than the 2 nd void 33. By making a large amount of contaminants contained in the fluid flow into the 2 nd gap 33 side, the amount of contaminants flying toward the flow rate measurement element 4 can be reduced, and therefore the contamination resistance is improved.

(example 2)

Embodiment 2 of the present embodiment will be described with reference to fig. 7 and 8. The same structure as that of embodiment 1 will not be described. In fig. 7, a portion of the end portion of the circuit board 15 that is hidden from view by the sensor module 10 is shown by a broken line.

The present embodiment is formed such that the width of the portion of the circuit substrate 15 located inside the sub-passage 12 (the distance in the flow direction of the fluid flowing in the sub-passage 12) is smaller than the width of the portion of the sensor assembly 10 located inside the sub-passage 12 (the distance in the flow direction of the fluid flowing in the sub-passage 12). An upstream end 19 of the sensor unit 10 in the sub passage 12 is located upstream of an upstream end 18 of the circuit board 15 in the sub passage 12.

In the present embodiment, the opening to the 3 rd gap is formed before the flow is branched into the D1 (the 1 st gap 32) and the D2 (the 2 nd gap 33), so that the flow path having a larger cross-sectional area than the D1 and the 3 rd gap 34 are in a branched relation, and the flow-dividing resistance of the 3 rd gap is increased, whereby the flow of air flowing into the 3 rd gap can be further suppressed, and the influence of the formation of the 3 rd gap on the fluid can be further suppressed.

As a further preferable example, the same effect can be obtained with respect to the reverse flow by configuring the downstream end 21 of the sensor unit 10 in the portion located in the sub passage to be located downstream of the downstream end 20 of the portion located in the sub passage 12 of the circuit board 15.

(example 3)

Embodiment 3 of the present invention will be described with reference to fig. 9. The same structure as that of the previous embodiment will not be described.

In the present embodiment, a recess 35 is formed in the cover 31, and the flow rate measurement element 4 is formed in the recess 35. In other words, the upstream end portion 19 of the sensor unit 10 is housed in the recess 35.

According to the present embodiment, since the 3 rd gap 34 is provided with an offset to the opening of the sub passage 12, the fluid flowing through the sub passage can be further suppressed from flowing into the 3 rd gap 34, and the influence of the formation of the 3 rd gap on the fluid can be further suppressed.

As a further preferable example, the same effect can be obtained with respect to the reverse flow by adopting a configuration in which the downstream end portion 21 of the sensor unit 10 is housed in the recess 35.

(example 4)

Embodiment 4 of the present invention will be described with reference to fig. 10. The same structure as that of the previous embodiment will not be described.

In the present embodiment, a projection shape (protruding portion) 36 is formed on the upstream side of the upstream end portion 19 of the sensor unit 10 of the cover 31. The projection shape 36 is a shape having an inclination on the upstream side. The upstream end 19 of the sensor unit 10 is located at a position shifted toward the cover 31 side from the apex of the protrusion 36. According to the present embodiment, since the fluid is guided to the 3 rd gap 34 on the opposite side of the opening of the sub passage 12 by the inclined shape, the inflow of the fluid into the 3 rd gap 34 can be further suppressed, and the influence on the fluid due to the formation of the 3 rd gap can be further suppressed.

As a further preferable example, a projection shape 36 having an inclination on the downstream side of the downstream end 21 of the sensor unit 10 is formed on the cover 10, and the downstream end 21 of the sensor unit 10 is disposed so as to be shifted toward the cover 31 side from the apex of the projection shape 36, whereby the same effect can be obtained with respect to the reverse flow.

(example 5)

Embodiment 5 of the present invention will be described with reference to fig. 11. The same structure as that of the previous embodiment will not be described.

In the present embodiment, the 2 nd gap 33 is made larger than the 1 st gap 32, and the 3 rd gap 34 is made larger than the 1 st gap 32. By adopting the structure in which the fluid is positively introduced into the 3 rd gap 34, the fouling can be positively caused to flow into the 3 rd gap 34, and the fouling resistance can be improved.

Description of the reference numerals

1 … … flow measuring device

3……LSI

4 … … flow detection element

5 … … lead frame

6 … … pressure sensor

7 … … humidity sensor

10 … … sensor assembly

11 … … casing

12 … … secondary path

13 … … throttle shape

14 … … recess

15 … … Circuit Board

17 … … adhesive

18 … … upstream end

19 … … upstream end

20 … … downstream end

21 … … downstream end

30 … … fluid

31 … … cover

32 … … No. 1 void

33 … … No. 2 gap

34 … … No. 3 void

35 … … recess

36 … … projection.