WO2022190666A1

WO2022190666A1 - Flowmeter

Info

Publication number: WO2022190666A1
Application number: PCT/JP2022/002160
Authority: WO
Inventors: 憲士朗長坂
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-03-12
Filing date: 2022-01-21
Publication date: 2022-09-15
Also published as: JP2022139760A

Abstract

A flowmeter (11) for measuring a flow rate of a fluid is provided with a flow passage unit (21) forming a flow passage (24) through which the fluid flows, and a sensor chip (51) attached to the flow passage unit. The flow passage unit has walls defining the flow passage. At least one wall among the walls defining the flow passage is a thin part, which is the thinnest part. The sensor chip includes a heater (53), a first temperature sensor (54), and a second temperature sensor (55). The sensor chip is attached to the thin part, and the thin part is formed from a resin.

Description

Flowmeter

The present disclosure relates to flow meters.

Patent Literature 1 describes a flowmeter that includes a channel unit that configures a channel and a sensor chip that is attached to the channel unit. A sensor chip is a chip on which a heater, a first temperature sensor, and a second temperature sensor are mounted. The heater heats the fluid flowing through the channel. The temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor can be used to measure the flow rate of the fluid flowing through the channel.

U.S. Pat. No. 6,813,944

In a flowmeter, if the wall between the sensor chip and the flow path is thin, heat is easily conducted between the fluid flowing through the flow path and the sensor chip. As a result, the measurement accuracy of the flowmeter is improved. On the other hand, if the wall between the sensor chip and the channel is thin, the increased pressure within the channel may cause the wall to flex. When the wall flexes, the sensor chip flexes. In this case, the sensor chip may be damaged.

A flow meter for solving the above problems is a flow meter for measuring the flow rate of a fluid, comprising a flow path unit forming a flow path through which the fluid flows, and a sensor chip attached to the flow path unit. , the flow channel unit has walls that partition the flow channel, at least one wall of the walls is a thin portion that is the thinnest portion, and the sensor chip includes a heater and a first temperature It has a sensor and a second temperature sensor, the sensor chip is attached to the thin portion, and the thin portion is made of resin.

A flow meter for solving the above problems is a flow meter for measuring the flow rate of a fluid, comprising a flow path unit forming a flow path through which the fluid flows, and a sensor chip attached to the flow path unit. , the sensor chip has a heater, a first temperature sensor, and a second temperature sensor; a metal foil located in the

According to the flowmeter of the present disclosure, it is possible to reduce the risk of damage to the sensor chip.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows 1st Embodiment of a flowmeter. Sectional view of the flowmeter cut along line 2-2. Sectional drawing which removed the case from FIG. Sectional drawing which shows 2nd Embodiment of a flowmeter. Sectional drawing which shows 3rd Embodiment of a flowmeter. Sectional drawing which shows 4th Embodiment of a flowmeter. Sectional drawing which shows 5th Embodiment of a flow meter. Sectional drawing which shows 6th Embodiment of a flow meter. Sectional drawing which shows 7th Embodiment of a flowmeter. Sectional view of the flowmeter cut along line 10-10. Sectional drawing which removed the case from FIG.

An embodiment of the flowmeter will be described below with reference to the drawings. The flow meter is a thermal type flow meter.
<First embodiment>
As shown in FIG. 1, the flow meter 11 is electrically connected to an external processing section 12 . The flow meter 11 outputs the detection result of the flow meter 11 to the processing section 12 . The flow rate of the fluid is measured by the processing unit 12 processing the detection result of the flowmeter 11 . The processing unit 12 includes a circuit that executes software processing for measuring the flow rate of fluid from the detection result of the flowmeter 11 . The processing unit 12 may comprise a hardware circuit such as an ASIC, for example. Flow meter 11 may include processing unit 12 .

The flow meter 11 is connected to the first external channel 13 and the second external channel 14 . The flow meter 11 relays between the first external channel 13 and the second external channel 14 . The flowmeter 11 is a flowmeter for measuring the flow rate of the fluid flowing from the first external flow path 13 to the second external flow path 14 or the flow rate of the fluid flowing from the second external flow path 14 to the first external flow path 13. be. In the first embodiment, fluid flows from the first external channel 13 towards the second external channel 14 . Therefore, in the first embodiment, the direction from the first external channel 13 to the second external channel 14 in the flow meter 11 is represented as the flow direction A1 in which the fluid flows.

In the first embodiment, each of the first external flow path 13 and the second external flow path 14 has a tube 15 and a connection member 16. A connection member 16 is attached to one end of the tube 15 . The tube 15 is connected to the flowmeter 11 by inserting the connection member 16 into the flowmeter 11 . The fluid flowing through the first external channel 13 and the second external channel 14 may be liquid or gas.

As an example, the flow meter 11 can measure the flow rate in the range of 10 nanoliters/minute to 10 milliliters/minute. In the first embodiment, the flow meter 11 can measure the flow rate in a minute range from 10 nanoliters/minute to 100 microliters/minute.

The flowmeter 11 includes a channel unit 21 and a sensor section 22 . In the first embodiment, the flowmeter 11 further includes a case 23. As shown in FIG.
The channel unit 21 constitutes a channel 24 . The channel 24 extends linearly. The channel 24 extends in the flow direction A1. The channel 24 is connected to the first external channel 13 and the second external channel 14 . One end of the channel 24 is connected to the first external channel 13 , and the other end of the channel 24 is connected to the second external channel 14 . Flow meter 11 measures the flow rate of fluid passing through channel 24 . In the first embodiment, the channel unit 21 includes a first base material 25 and a second base material 26 .

As shown in FIGS. 1 and 2, the first base material 25 has recesses 27 that form the flow paths 24 . The recess 27 extends linearly in the first base material 25 . The recesses 27 extend in the flow direction A1 in the first base material 25 . The first base material 25 has a facing surface 28 that faces the second base material 26 . A recess 27 is formed in the facing surface 28 .

The first base material 25 is made of resin, for example. In the first embodiment, the first base material 25 is made of acrylic (PMMA), for example. The first base material 25 is not limited to resin, and may be made of glass, for example. The material forming the first base material 25 may be the same as or different from the material forming the second base material 26 .

The second base material 26 is adhered to the first base material 25 so as to cover the recess 27 . Specifically, the second base material 26 is adhered to the facing surface 28 of the first base material 25 . The second base material 26 is adhered to the first base material 25 by, for example, an adhesive. By bonding the second base material 26 to the first base material 25 , the concave portion 27 is covered with the second base material 26 . Thereby, the flow path 24 is configured.

The second base material 26 is, for example, a film. The second base material 26 is made of resin, for example. In the first embodiment, the second substrate 26 is made of, for example, vinyl chloride (PVC), high density polyethylene (HDPE), polyacetal (POM), acrylic (PMMA), polyamide 6 (PA6), or the like. The resin forming the second base material 26 is preferably a material with low water absorption, high thermal conductivity, and high Young's modulus.

As shown in FIG. 3, the thickness of the second base material 26 is smaller than the thickness of the first base material 25 in the first embodiment. The thickness of the first base material 25 and the thickness of the second base material 26 compared here are the lengths in the direction in which the first base material 25 and the second base material 26 are laminated.

In the first embodiment, the shape of the channel unit 21 and the channel 24 is rectangular when viewed from the flow direction A1 or its opposite direction. Therefore, the channel unit 21 has a first outer surface 31, a second outer surface 32, a third outer surface 33, and a fourth outer surface 34 as outer peripheral surfaces. The channel unit 21 has a first inner surface 36, a second inner surface 37, a third inner surface 38, and a fourth inner surface 39 as inner peripheral surfaces. The inner peripheral surface of the channel unit 21 is a surface forming the channel 24 . That is, the first inner surface 36 , the second inner surface 37 , the third inner surface 38 , and the fourth inner surface 39 constitute the flow path 24 .

In the first embodiment, the first base material 25 has a first outer surface 31, a second outer surface 32 and a third outer surface 33. The first substrate 25 has a first interior surface 36 , a second interior surface 37 and a third interior surface 38 . The first inner surface 36 , the second inner surface 37 and the third inner surface 38 are surfaces forming the recess 27 . Second substrate 26 has a fourth outer surface 34 . Second substrate 26 has a fourth inner surface 39 .

The first base material 25 has a first wall 41 , a second wall 42 and a third wall 43 as part of walls that partition the flow path 24 . The first wall 41 , the second wall 42 and the third wall 43 constitute the recess 27 . The first wall 41 is connected to the second wall 42 and the third wall 43 . First wall 41 includes a first outer surface 31 and a first inner surface 36 . The second wall 42 faces the third wall 43 . Second wall 42 includes facing surface 28 , second outer surface 32 and second inner surface 37 . Third wall 43 includes facing surface 28 , third outer surface 33 and third inner surface 38 .

The second base material 26 has a fourth wall 44 as part of the wall that partitions the channel 24 . A fourth wall 44 is adhered to the second wall 42 and the third wall 43 . Specifically, the fourth wall 44 is adhered to the facing surface 28 . Thereby, the fourth wall 44 covers the recess 27 . As a result, the fourth wall 44 faces the first wall 41 . Fourth wall 44 includes a fourth outer surface 34 and a fourth inner surface 39 .

The channel unit 21 has a first wall 41 , a second wall 42 , a third wall 43 and a fourth wall 44 as walls that partition the channel 24 . That is, the walls that partition the flow path 24 include a plurality of walls (first wall 41, second wall 42, third wall 43, and fourth wall 44 in this embodiment). In the channel unit 21, when viewed from the flow direction A1 or the opposite direction, in the radial direction centered on the channel 24, between the inner peripheral surface of the channel unit 21 and the outer peripheral surface of the channel unit 21 The distance is the thickness of the wall that partitions the channel 24 . The thickness of the wall that partitions the channel 24 is the length in the direction perpendicular to the inner peripheral surface of the channel unit 21 and the outer peripheral surface of the channel unit 21 .

In the first embodiment, the thickness of the wall that partitions the flow path 24 is not uniform, and varies depending on the shape of the flow path unit 21 and the shape of the flow path 24 . That is, in the first embodiment, the thickness of the first wall 41, the thickness of the second wall 42, the thickness of the third wall 43, and the thickness of the fourth wall 44 are not uniform. The thickness of the first wall 41 is the first thickness W1. The thickness of the second wall 42 is the second thickness W2. The thickness of the third wall 43 is the third thickness W3. The thickness of the fourth wall 44 is the fourth thickness W4.

The first thickness W1 is the distance between the first outer surface 31 and the first inner surface 36. A second thickness W2 is the distance between the second outer surface 32 and the second inner surface 37 . A third thickness W3 is the distance between the third outer surface 33 and the third inner surface 38 . A fourth thickness W4 is the distance between the fourth outer surface 34 and the fourth inner surface 39 .

In the first embodiment, the fourth thickness W4 is the smallest among the first thickness W1, the second thickness W2, the third thickness W3, and the fourth thickness W4. Therefore, in the first embodiment, the fourth wall 44 corresponds to the thinnest portion among the walls that partition the flow path 24 . Thus, at least one of the walls defining the channel 24 is a thin portion. That is, at least one wall (this In an embodiment, the fourth wall 44) is a thinned portion. The fourth thickness W4 is also the thickness of the second base material 26 . The first thickness W1 is, for example, 1 mm or more. The fourth thickness W4 is, for example, 10 micrometers or more and 300 micrometers or less.

As shown in FIG. 1, the sensor section 22 is attached to the channel unit 21 . In the first embodiment, the sensor section 22 is attached to the second base material 26 . Specifically, the sensor unit 22 is attached to the surface of the second base material 26 opposite to the surface that contacts the first base material 25 . That is, the sensor section 22 is attached to the fourth outer surface 34 . In the first embodiment, the sensor section 22 has a sensor chip 51 and a support section 52 .

The sensor chip 51 is attached to the channel unit 21 by attaching the sensor section 22 to the channel unit 21 . In the first embodiment, sensor chip 51 is attached to second substrate 26 . For example, the sensor chip 51 is attached to the second base material 26 by covering the sensor section 22 and the flow path unit 21 with the case 23 in a state in which the sensor section 22 and the flow path unit 21 are stacked.

As shown in FIG. 3 , the sensor chip 51 is positioned near the channel 24 by attaching the sensor section 22 to the channel unit 21 . In the first embodiment, the sensor chip 51 is attached to the fourth wall 44 , which is the thinnest portion of the walls that partition the flow path 24 . In the first embodiment, the fourth wall 44 corresponds to the thin portion. In other words, the thin portion is the portion between the channel 24 and the sensor chip 51 in the wall that partitions the channel 24 .

The thickness of the thin portion is, for example, 10 micrometers or more and 300 micrometers or less. If the thickness of the thin portion is less than 10 micrometers, the thin portion tends to bend, although this depends on the type of resin that constitutes the thin portion. When the thickness of the thin portion exceeds 300 micrometers, there are difficulties in heat conduction.

As shown in FIG. 1, the sensor chip 51 has a heater 53, a first temperature sensor 54, a second temperature sensor 55, and a substrate 56. The heater 53 , first temperature sensor 54 and second temperature sensor 55 are mounted on the substrate 56 . The heater 53 , the first temperature sensor 54 , and the second temperature sensor 55 come into contact with the channel unit 21 by attaching the sensor section 22 to the channel unit 21 . In the first embodiment, the heater 53 , the first temperature sensor 54 and the second temperature sensor 55 are in contact with the second substrate 26 .

The heater 53 generates heat when energized. The heater 53 heats the fluid flowing through the flow path 24 by generating heat. In the first embodiment, heater 53 heats the fluid through second substrate 26 .

The first temperature sensor 54 and the second temperature sensor 55 are positioned on the substrate 56 so as to sandwich the heater 53 therebetween. When the sensor section 22 is attached to the channel unit 21, the first temperature sensor 54, the heater 53, and the second temperature sensor 55 are arranged in this order in the flow direction A1. A first temperature sensor 54 and a second temperature sensor 55 detect the temperature of the fluid flowing through the channel 24 . Thus, in the first embodiment, the sensor chip 51 heats the fluid and detects the temperature of the fluid through the thin fourth wall 44 .

The detection result of the first temperature sensor 54 and the detection result of the second temperature sensor 55 are sent to the processing unit 12 . The processing unit 12 obtains the temperature distribution of the fluid from the detection result of the first temperature sensor 54 and the detection result of the second temperature sensor 55 . Thereby, the flow rate of the fluid flowing through the channel 24 is measured.

The support portion 52 supports the sensor chip 51 . The support portion 52 is provided so as to surround the sensor chip 51 . The support portion 52 has an exposure opening 57 through which the sensor chip 51 is exposed. The support portion 52 contacts the channel unit 21 by attaching the sensor portion 22 to the channel unit 21 . In the first embodiment, the support portion 52 contacts the second base material 26 .

As shown in FIGS. 1 and 2, the case 23 covers the channel unit 21 and the sensor section 22. The case 23 protects the flow path unit 21 and the sensor section 22 by covering the flow path unit 21 and the sensor section 22 .

The case 23 has a first case member 61 and a second case member 62 . The first case member 61 and the second case member 62 are configured to be assembled with each other. The first case member 61 and the second case member 62 are assembled so as to sandwich the channel unit 21 and the sensor section 22 . By assembling the first case member 61 and the second case member 62, the channel unit 21 and the sensor section 22 are held in contact with each other. In other words, when the first case member 61 and the second case member 62 are separated, the sensor section 22 can be removed from the channel unit 21 . Thus, the flow meter 11 is configured such that the sensor section 22 can be replaced.

Instead of the case 23, a clamp may be provided to hold the channel unit 21 and the sensor section 22 in contact with each other. Alternatively, the sensor section 22 may be attached to the channel unit 21 by, for example, an adhesive without using the case 23 .

The case 23 has a first opening 63 and a second opening 64 . In the first embodiment, the first opening 63 and the second opening 64 are configured by assembling the first case member 61 and the second case member 62 together. The first opening 63 and the second opening 64 may be provided in the first case member 61 or may be provided in the second case member 62 .

The first opening 63 and the second opening 64 communicate with both ends of the channel 24 respectively. The first opening 63 communicates with one end of the channel 24 . Therefore, the first external channel 13 and the channel 24 are connected through the first opening 63 . The second opening 64 communicates with the other end of the channel 24 . Therefore, the second external channel 14 and the channel 24 are connected through the second opening 64 .

The case 23 has an opening 65 that communicates with the exposure opening 57 while holding the channel unit 21 and the sensor section 22 . In the first embodiment, the opening 65 is provided in the second case member 62 . That is, when the channel unit 21 and the sensor section 22 are held by the case 23 , the sensor chip 51 is exposed through the exposure opening 57 and the opening 65 . That is, a cavity facing the sensor chip 51 is formed in the case 23 . The cavity reduces the possibility of heat diffusion from the sensor chip 51 . That is, by providing the cavity, the measurement accuracy of the flowmeter 11 is improved.

Next, operation of the first embodiment will be described.
The sensor chip 51 heats the fluid and detects the temperature of the fluid through the walls that partition the flow path 24 . The position of the sensor chip 51 is preferably closer to the channel 24 . The reason for this is that the smaller the distance between the sensor chip 51 and the channel 24 , that is, the thinner the wall with which the sensor chip 51 contacts, the more heat is conducted between the fluid flowing through the channel 24 and the sensor chip 51 . This is because it becomes easier. This improves the measurement accuracy of the flow meter 11 .

When the flow rate of the fluid flowing through the channel 24 increases, the pressure inside the channel 24 increases. When the pressure inside the flow path 24 increases, the walls defining the flow path 24 may bend. That is, in the first embodiment, the first wall 41, the second wall 42, the third wall 43, and the fourth wall 44 may bend. In particular, the thin portion, which is the thinnest portion of the wall that partitions the flow path 24, tends to bend. Therefore, in the first embodiment, the fourth wall 44 is easily bent.

A sensor chip 51 is attached to the thin fourth wall 44 from the viewpoint of heat conduction. Therefore, when the fourth wall 44 bends, the sensor chip 51 bends. If the sensor chip 51 bends, the sensor chip 51 may be damaged. In this regard, the fourth wall 44, that is, the second base material 26 is made of resin. In particular, in the first embodiment, the second base material 26 is made of resin with a high Young's modulus. Therefore, even if the pressure inside the flow path 24 increases, the fourth wall 44 is less likely to bend. Therefore, the sensor chip 51 is less likely to bend. Therefore, the sensor chip 51 is less likely to be damaged.

Next, effects of the first embodiment will be described.
(1-1) The flowmeter 11 includes a channel unit 21 forming the channel 24 and a sensor chip 51 attached to the channel unit 21 . The channel unit 21 has walls that partition the channels 24 . At least one of the walls defining the flow path 24 is a thin portion, which is the thinnest portion. The sensor chip 51 has a heater 53, a first temperature sensor 54, and a second temperature sensor 55, and is attached to the fourth wall 44 corresponding to the thin portion. The fourth wall 44 is made of resin.

According to the above configuration, since the fourth wall 44 is made of resin, it is difficult to bend even if the pressure inside the flow path 24 increases. Therefore, the sensor chip 51 is less likely to be damaged.
Furthermore, another effect is that the fourth wall 44 is strong because it is made of resin. Therefore, even if the fourth wall 44 receives an impact when replacing the sensor section 22 with respect to the channel unit 21, the fourth wall 44 is less likely to be damaged.

(1-2) The channel unit 21 includes a first base material 25 having a concave portion 27 forming the channel 24, a second base material 26 adhered to the first base material 25 so as to cover the concave portion 27, Consists of The first base material 25 has a first wall 41 , a second wall 42 and a third wall 43 as part of the walls forming the flow path 24 . The second base material 26 has a fourth wall 44 as part of the walls that form the channel 24 . The recess 27 is composed of a first wall 41 , a second wall 42 and a third wall 43 . According to the above configuration, it becomes easier to manufacture the channel unit 21 .

(1-3) The heater 53 is positioned between the first temperature sensor 54 and the second temperature sensor 55 in the direction in which the flow path 24 extends, that is, the flow direction A1. According to the above configuration, the first temperature sensor 54 and the second temperature sensor 55 can detect the temperature of the fluid at two points, upstream of the flow path 24 and downstream of the flow path 24 . Thereby, the flow rate of the fluid can be measured.

(1-4) The flowmeter 11 includes a case 23 that covers the flow channel unit 21 and the sensor chip 51 . The case 23 has a first case member 61 and a second case member 62 that can be attached to the first case member 61 . According to the above configuration, the case 23 can protect the channel unit 21 and the sensor chip 51 .

Furthermore, as another effect, the sensor chip 51 can be removed from the channel unit 21 by separating the first case member 61 and the second case member 62 . Thereby, the sensor chip 51 can be replaced with respect to the channel unit 21 .

<Second embodiment>
Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that the sensor section 22 is attached to the first base material 25 . In the second embodiment, the configuration different from that of the first embodiment will be mainly described, and the description of other configurations will be omitted.

As shown in FIG. 4 , in the second embodiment, the thickness of the first base material 25 is smaller than the thickness of the second base material 26 . Therefore, in the second embodiment, the first wall 41 of the walls that partition the flow path 24 corresponds to the thin portion. Therefore, in the second embodiment, the sensor chip 51 is attached to the first wall 41 by attaching the sensor portion 22 to the first base material 25 .

In the second embodiment, the first base material 25 is made of, for example, vinyl chloride (PVC), high density polyethylene (HDPE), polyacetal (POM), acrylic (PMMA), polyamide 6 (PA6), or the like. The resin forming the first base material 25 is preferably a material with low water absorption, high thermal conductivity, and high Young's modulus. In the second embodiment, the second base material 26 is made of acrylic (PMMA), for example. The second base material 26 is not limited to resin, and may be made of glass, for example.

According to the second embodiment, the following effects are obtained.
(2-1) Since the first wall 41 is made of resin, it is difficult to bend even if the pressure inside the flow path 24 increases. Therefore, the sensor chip 51 is less likely to be damaged. Furthermore, as another effect, since the first wall 41 is made of resin, it has strength. Therefore, even if the first wall 41 receives an impact when replacing the sensor section 22 with respect to the channel unit 21, the first wall 41 is less likely to be damaged.

<Third Embodiment>
Next, a third embodiment will be described. In the third embodiment, as compared with the first embodiment, the flow channel unit 21 is not configured to include the first base material 25 and the second base material 26, but is composed of a single base material 67. different in that respect. In the third embodiment, the configuration different from that of the first embodiment will be mainly described, and the description of other configurations will be omitted.

As shown in FIG. 5, the channel unit 21 has a channel 24 in the third embodiment. In the third embodiment, the flow channel unit 21 is configured by a single base material 67 instead of including the first base material 25 and the second base material 26 that are adhered to each other. The base material 67 has walls that partition the flow paths 24 . The base material 67 has, for example, a first wall 41 , a second wall 42 , a third wall 43 , and a fourth wall 44 as walls that partition the flow path 24 . The first wall 41 is connected to the second wall 42 and the third wall 43 . A fourth wall 44 is connected to the second wall 42 and the third wall 43 . Therefore, in 3rd Embodiment, the 1st wall 41, the 2nd wall 42, the 3rd wall 43, and the 4th wall 44 are comprised integrally. In one example, the substrate 67 is a one-piece piece of resin, for example. The channel 24 is provided so as to penetrate the base material 67 .

The base material 67 is made of, for example, vinyl chloride (PVC), high density polyethylene (HDPE), polyacetal (POM), acrylic (PMMA), polyamide 6 (PA6), or the like.

According to the third embodiment, the following effects are obtained.
(3-1) Since the channel unit 21 is composed of the single base material 67, the strength of the channel unit 21 is improved.

<Fourth Embodiment>
Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment in that the channel unit 21 has a metal foil 71 . In the fourth embodiment, the configuration different from that of the first embodiment will be mainly described, and the description of other configurations will be omitted.

As shown in FIG. 6, the channel unit 21 has a metal foil 71 in the fourth embodiment. A metal foil 71 is positioned between the sensor chip 51 and the channel 24 . Specifically, the metal foil 71 is positioned between the heater 53 , the first temperature sensor 54 , the second temperature sensor 55 and the flow path 24 . In the fourth embodiment, the metal foil 71 is embedded in the walls that partition the flow paths 24 . In other words, the metal foil 71 is embedded in the wall (the fourth wall 44 in this embodiment) that defines the channel 24 located between the sensor chip 51 and the channel 24 . Specifically, the metal foil 71 is embedded in the thin portion, that is, the fourth wall 44 . The metal foil 71 is, for example, SUS, aluminum, or the like.

According to the fourth embodiment, the following effects are obtained.
(4-1) The channel unit 21 has a metal foil 71 between the sensor chip 51 and the channel 24 .

According to the above configuration, the metal foil 71 facilitates heat conduction between the fluid flowing through the channel 24 and the sensor chip 51 . This improves the measurement accuracy of the flow meter 11 . Another effect is that the metal foil 71 can improve the rigidity of the fourth wall 44 . That is, the fourth wall 44 becomes difficult to bend.

(4-2) The metal foil 71 is positioned between the heater 53 , the first temperature sensor 54 , the second temperature sensor 55 and the channel 24 .
According to the above configuration, the metal foil 71 effectively conducts the heat of the heater 53 to the fluid flowing through the flow path 24 . Moreover, the metal foil 71 allows the first temperature sensor 54 and the second temperature sensor 55 to accurately detect the temperature of the fluid flowing through the flow path 24 .

(4-3) The metal foil 71 is embedded in the walls that partition the channel 24 .
According to the above configuration, the metal foil 71 is less likely to rust. Therefore, a metal that easily rusts, such as aluminum, can be used as the metal foil 71 .

<Fifth Embodiment>
Next, a fifth embodiment will be described. In the fifth embodiment, the number of metal foils 71 is different from that in the fourth embodiment. In the fifth embodiment, the configuration different from that of the fourth embodiment will be mainly described, and the description of other configurations will be omitted.

As shown in FIG. 7, the channel unit 21 has a plurality of metal foils 71 in the fifth embodiment. The channel unit 21 has, for example, three metal foils 71, but may have four or more, or may have two. A plurality of metal foils 71 are positioned between the sensor chip 51 and the channel 24 . In the fifth embodiment, the multiple metal foils 71 are embedded in the walls that partition the flow paths 24 . Specifically, the plurality of metal foils 71 are embedded in the thin portion, that is, the fourth wall 44 . A plurality of metal foils 71 are arranged in the flow direction A1 on the fourth wall 44 .

A first metal foil, which is one of the plurality of metal foils 71 , is positioned between the heater 53 and the channel 24 . A second metal foil, which is one of the plurality of metal foils 71 , is positioned between the first temperature sensor 54 and the channel 24 . A third metal foil, which is one of the plurality of metal foils 71 , is positioned between the second temperature sensor 55 and the channel 24 . That is, in the fifth embodiment, the metal foil 71 is divided so as to correspond to the heater 53, the first temperature sensor 54, and the second temperature sensor 55, respectively, as compared with the fourth embodiment.

According to the fifth embodiment, the following effects are obtained.
(5-1) Since the metal foil 71 is divided so as to correspond to the heater 53, the first temperature sensor 54, and the second temperature sensor 55, the heat of the heater 53 is Conduction to the first temperature sensor 54 and the second temperature sensor 55 via the foil 71 becomes difficult. Thereby, the first temperature sensor 54 and the second temperature sensor 55 can accurately detect the temperature of the fluid.

<Sixth embodiment>
Next, a sixth embodiment will be described. In the sixth embodiment, the position of the metal foil 71 is different from that in the fourth embodiment. In the sixth embodiment, the configuration different from that of the fourth embodiment will be mainly described, and the description of other configurations will be omitted.

As shown in FIG. 8, the channel unit 21 has a metal foil 71 in the sixth embodiment. A metal foil 71 is positioned between the sensor chip 51 and the channel 24 . In the sixth embodiment, the metal foil 71 is positioned between the sensor section 22 and the second base material 26 . Specifically, the metal foil 71 is positioned between the fourth wall 44 and the sensor chip 51 . That is, in the sixth embodiment, the metal foil 71 is sandwiched between the sensor section 22 and the second base material 26 without being embedded in the second base material 26 .

The metal foil 71 is provided over the sensor chip 51 and the support portion 52 . That is, in the sixth embodiment, heat is more easily diffused from the sensor chip 51 by the metal foil 71 than in the fourth embodiment, but the effect (4-1) described above can be obtained. According to the sixth embodiment, the following effects are obtained.

(6-1) Since the metal foil 71 is positioned between the fourth wall 44 and the sensor chip 51 , the flow channel unit 21 is easier to manufacture than the configuration in which the metal foil 71 is embedded in the fourth wall 44 .
(6-2) Since the metal foil 71 is provided over the sensor chip 51 and the support portion 52, the rigidity of the fourth wall 44 can be further improved. That is, the fourth wall 44 becomes difficult to bend.

<Seventh embodiment>
Next, a seventh embodiment will be described. In the seventh embodiment, the thickness of the wall that partitions the flow path 24 is different from that in the fourth embodiment. In the seventh embodiment, the configuration different from that of the fourth embodiment will be mainly described, and the description of other configurations will be omitted.

As shown in FIGS. 9, 10, and 11, in the seventh embodiment, the first wall 41 is the thinnest among the walls that partition the channel 24. As shown in FIGS. Therefore, in the seventh embodiment, not the fourth wall 44 but the first wall 41 corresponds to the thin portion. In the seventh embodiment, the first thickness W1 is the smallest among the first thickness W1, the second thickness W2, the third thickness W3, and the fourth thickness W4. The sensor chip 51 is attached to the fourth wall 44 as in the fourth embodiment. That is, in the seventh embodiment, the sensor chip 51 is not attached to the thin portion.

The metal foil 71 is positioned between the sensor chip 51 and the channel 24. The metal foil 71 is embedded in walls that partition the flow path 24 . Specifically, the metal foil 71 is embedded in the fourth wall 44 .

In the seventh embodiment, the sensor chip 51 is not attached to the thin portion, but the metal foil 71 is positioned between the sensor chip 51 and the channel 24. Therefore, even if the sensor chip 51 is not attached to the thin portion, heat is easily conducted between the fluid flowing through the channel 24 and the sensor chip 51 .

According to the seventh embodiment, the following effects are obtained.
(7-1) The flowmeter 11 includes a flow path unit 21 forming a flow path 24 and a sensor chip 51 attached to the flow path unit 21 . The sensor chip 51 has a heater 53 , a first temperature sensor 54 and a second temperature sensor 55 . The channel unit 21 has a wall that partitions the channel 24 and a metal foil 71 positioned between the sensor chip 51 and the channel 24 .

According to the above configuration, the metal foil 71 facilitates heat conduction between the fluid flowing through the channel 24 and the sensor chip 51 . Therefore, the thickness of the fourth wall 44 can be set so that it is difficult to bend. Thereby, even if the pressure in the flow path 24 increases, the fourth wall 44 is less likely to bend. Therefore, the sensor chip 51 is less likely to be damaged.

The first to seventh embodiments can be modified and implemented as follows. The first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment, the sixth embodiment, the seventh embodiment, and the following modifications are combined with each other within a technically consistent range. can be implemented.

- When viewed from the flow direction A1 or the opposite direction, the shape of the channel unit 21 is not limited to a rectangular shape, and may be polygonal or circular.
- The shape of the flow path 24 is not limited to a rectangular shape when viewed from the flow direction A1 or the opposite direction. It may be polygonal or circular.

- All features disclosed in the specification and/or claims are for the purposes of the original disclosure and claimed independently of any combination of features in the embodiments and/or claims. They are intended to be disclosed separately and independently of each other for the purpose of limiting the scope of the invention. Statements representing all numerical ranges or collections of elements are for the purposes of the initial disclosure and for the purposes of limiting the claimed invention, and specifically as limitations on numerical ranges, all possible Intermediate values or intermediate components are disclosed.

REFERENCE SIGNS LIST 11 flow meter 12 processing section 13 first external flow path 14 second external flow path 15 tube 16 connecting member 21 flow path unit 22 sensor section 23 case 24 flow path 25 first substrate 26 second substrate 27 concave portion 28 opposing surface 31 first outer surface 32 second outer surface 33 third outer surface 34 fourth outer surface 36 first inner surface 37 second inner surface 38 third inner surface 39 fourth inner surface 41 first wall 42 second wall 43 third wall 44 fourth wall 51 sensor Chip 52 Supporting Part 53 Heater 54 First Temperature Sensor 55 Second Temperature Sensor 56 Substrate 57 Exposure Port 61 First Case Member 62 Second Case Member 63 First Opening 64 Second Opening 65 Open Port 67 Base Material 71 Metal Foil A1 Flow Direction W1 First thickness W2 Second thickness W3 Third thickness W4 Fourth thickness

Claims

A flow meter for measuring the flow rate of a fluid, comprising:
a channel unit configuring a channel through which the fluid flows;
a sensor chip attached to the channel unit,
The channel unit has a wall that partitions the channel,
at least one of said walls is a thin portion being the thinnest portion;
The sensor chip has a heater, a first temperature sensor, and a second temperature sensor,
The sensor chip is attached to the thin portion,
The flowmeter, wherein the thin portion is made of resin.
A flow meter for measuring the flow rate of a fluid, comprising:
a channel unit configuring a channel through which the fluid flows;
a sensor chip attached to the channel unit,
The sensor chip has a heater, a first temperature sensor, and a second temperature sensor,
The flow meter, wherein the flow path unit includes a wall that partitions the flow path, and a metal foil positioned between the sensor chip and the flow path.
at least one of said walls is a thin portion being the thinnest portion;
The sensor chip is attached to the thin portion,
The flowmeter according to claim 2, wherein the thin portion is made of resin.
The flowmeter according to claim 2 or 3, wherein the metal foil is embedded in the wall.
The metal foil is a first metal foil,
The channel unit has a second metal foil and a third metal foil,
The first metal foil is positioned between the heater and the flow path,
The second metal foil is positioned between the first temperature sensor and the flow path,
5. The flow meter of Claim 4, wherein the third metal foil is positioned between the second temperature sensor and the flow path.
The flowmeter according to claim 2 or 3, wherein the metal foil is positioned between the wall and the sensor chip.
The channel unit includes a first base material having a recess forming the channel, and a second base material adhered to the first base material so as to cover the recess,
The first substrate has a portion of the wall,
The second substrate has a portion of the wall,
The flowmeter according to any one of claims 1 to 6, wherein the recess is configured by part of the wall of the first base material.
The flowmeter according to any one of claims 1 to 7, wherein the heater is positioned between the first temperature sensor and the second temperature sensor in the direction in which the flow path extends.
A case covering the flow path unit and the sensor chip,
The flowmeter according to any one of claims 1 to 8, wherein the case has a first case member and a second case member that can be attached to the first case member.