Physical quantity measuring device

Abstract

The purpose of the present disclosure is to provide a physical quantity measurement device that makes it possible to measure the flow rate of a gas or the concentration of a component of the gas with good stability even in a high-humidity environment in which water droplets are contained in a fluid to be measured. A physical quantity measurement device (22) is provided with a flow path main body (11), a flow rate measurement unit, an upstream opening (17), a downstream opening (18), and a sub-flow path (13). The flow path main body (11) includes a main flow path (9). The flow measuring unit is placed in the main flow path (9). An upstream opening (17) is placed upstream of the main flow path (9). A downstream opening (18) is placed downstream of the main flow path (9). The sub-flow path (13) is placed on the outside of the main flow path (9) so as to connect the upstream opening (17) and the downstream opening (18) to each other. The sub-flow path (13) has a constricted section (27) for reducing the cross-sectional area of the flow path.

Description

Technical Field

[0001] The present disclosure relates to a physical quantity measuring device for measuring the flow rate of a gas or the concentration of a component contained in the gas without water droplets having an influence on a fluid containing water. Background Art

[0002] Patent document 1 discloses a physical quantity measuring device for measuring the flow rate of a fluid or the concentration of a component contained in the fluid without water droplets affecting the fluid containing water. In the measuring device, the measured fluid is divided into a flow that turns to a main flow path (on which the physical quantity is assumed to be measured) and a flow that turns to a secondary flow path (which is set as a bypass path for the main flow path and on which the physical quantity is assumed not to be measured), and then the two flows of the fluid merge again at a downstream point. In this case, water droplets contained in the measured fluid flow through the secondary flow path.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-25751 Summary of the invention

[0006] An object of the present disclosure is to provide a physical quantity measuring device that can not only accurately measure the flow rate or concentration of the gas in a high humidity environment even if condensed dew is contained in an inflowing fluid such as a gas, but also ensure a path for the condensed dew.

[0007] The physical quantity measuring device according to the present disclosure includes a flow path body, a flow measurement unit, a signal processing unit, an upstream opening, a downstream opening and a secondary flow path. The flow path body includes a main flow path. The flow measurement unit is set for the main flow path. The signal processing unit receives a signal from the flow measurement unit to measure the flow rate of the fluid. The upstream opening is set upstream of the main flow path. The downstream opening is set downstream of the main flow path. The secondary flow path is set outside the main flow path so that the upstream opening and the downstream opening are connected to each other. The secondary flow path has a narrowing portion for reducing the cross-sectional area of ​​the flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A perspective view illustrating the structure of a flow measurement device according to a first embodiment and showing the appearance of a flow path portion;

[0009] Figure 2 yes Figure 1 An exploded view of a flow path portion according to a first embodiment is shown;

[0010] Figure 3 is an example Figure 1 An exploded view of a portion of a cross section of a flow path portion according to a first embodiment is shown;

[0011] Figure 4 The A is along Figure 1 A schematic cross-sectional view of a flow path portion according to a first embodiment taken along a plane A1-A2 shown;

[0012] Figure 4 B is Figure 1 An exploded view of the flow path portion shown;

[0013] Figure 5 The A is along Figure 1 A cross-sectional view of the flow path portion according to the first embodiment taken along the plane B1-B2 shown;

[0014] Figure 5 B is along Figure 5 A schematic cross-sectional view taken along the plane C1-C2 shown in FIG.

[0015] Figure 6 is an example along the Figure 4 A cross section according to the first embodiment taken by the plane A1-A2 shown in FIG. Figure 5 An enlarged plan view of the narrowing portion shown in section G of A;

[0016] Figure 7 It is along Figure 6 A schematic cross-sectional view of the constriction according to the first embodiment taken along the plane D1-D2 shown;

[0017] Figure 8 illustrates the flow operation of the constriction according to the first embodiment;

[0018] Fig. 9 is a graph showing a flow resistance curve of a measured fluid on a flow path and a flow resistance curve of a measured fluid on a main flow path according to the first embodiment; and

[0019] Fig.10 This is a partial cross-sectional view of a flow path portion of a known physical quantity measuring device. DETAILED DESCRIPTION

[0020] (Knowledge constituting the basis of the present disclosure)

[0021] When the inventors conceived the concept of the present disclosure, for the purpose of measuring a physical quantity such as flow rate of a gas containing water, a Fig.10 The physical quantity measuring device 100 such as the physical quantity measuring device 100 shown can be used as a device for forming a sub-flow path for removing water droplets from a fluid to be measured. Fig.10: is a partial cross-sectional view of the flow path portion of such a physical quantity measuring device 100. According to this structure, the measured fluid is divided into a flow toward the main flow path 105 (on which the physical quantity is assumed to be measured) and a flow toward the secondary flow path 104 (the secondary flow path 104 is provided as a bypass path for the main flow path, and on which the physical quantity is assumed not to be measured), and then the two flows of the fluid merge again at a downstream point. In this case, water droplets contained in the measured fluid flow away through the secondary flow path 104.

[0022] The secondary flow path 104 thus formed has dimensions including a width W1 and a height F. These dimensions are generally considered to be values ​​sufficient to cause the desired water droplets to stagnate or flow.

[0023] However, the inventors have found that there are challenges such as the bypass method through the secondary flow path 104 causing a large change in the flow rate (resistance change) of the measured fluid due to the presence or absence of water droplets, which leads to errors in measurement accuracy. The inventors have conceived the subject matter of the present disclosure to overcome such problems.

[0024] Thus, the physical quantity measuring device according to the present disclosure includes a flow path main body, a flow measurement unit, a signal processing unit, an upstream opening, a downstream opening and a secondary flow path. The flow path main body includes a main flow path. The flow measurement unit is set for the main flow path. The signal processing unit receives a signal from the flow measurement unit to measure the flow rate of the fluid. The upstream opening is set upstream of the main flow path. The downstream opening is set downstream of the main flow path. The secondary flow path is set on the outside of the main flow path so that the upstream opening and the downstream opening are connected to each other. The secondary flow path has a narrowing portion along which the passage cross-section of the secondary flow path is narrowed. This makes it possible to reduce the flow change (i.e., resistance change) of the fluid passing through the secondary flow path depending on whether any water droplets are contained in the secondary flow path, thereby helping to reduce measurement errors. As used herein, the phrase "outside of the main flow path" where the secondary flow path is set also refers to a space other than the space where the main flow path is formed.

[0025] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Note that unnecessary detailed descriptions will be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same structures will be omitted.

[0026] It should also be noted that the accompanying drawings and the following descriptions are provided by the applicant in order to assist those of ordinary skill in the art to fully understand the present disclosure, and should not be construed as limiting the scope of the present disclosure defined by the appended claims.

[0027] (First embodiment)

[0028] Now refer to Figures 1 to 9 The first embodiment will be described.

[0029] [1-1. Structure]

[0030] Figure 1 A perspective view illustrating the structure of a flow measurement device according to a first embodiment of the present disclosure and showing the appearance of a flow path portion. Figure 2 yes Figure 1 Exploded view of the flow path section shown. Figure 3 is an example Figure 1 An exploded view of a partial cross section of the flow path portion is shown. Figure 4 A and Figure 4 B is along Figure 1 Schematic cross-sectional view and exploded view of the flow path portion taken along plane A1-A2 are shown. Figure 5 A and Figure 5 B is along Figure 1 The planes B1-B2 and Figure 5 A is a cross-sectional view of the flow path portion taken along the plane C1-C2 shown in FIG. Figure 6 yes Figure 5 An enlarged plan view of the narrowed portion shown in part G of A. Figure 7 It is along Figure 6 A cross-sectional view of the constriction taken along the plane D1 - D2 is shown. Figure 8 The flow operation of the constriction is illustrated. Fig. 9 It is a graph showing a flow resistance curve of the measured fluid on the flow path and a flow resistance curve of the measured fluid on the main flow path.

[0031] exist Figure 1 In the flow path section 1, a fluid inlet 2 through which a measured fluid (hereinafter referred to as "fluid") flows in, and a fluid outlet 3 through which the measured fluid flows out. In addition, the flow path section 1 also includes a pressure sensor 4, a relative humidity sensor 5 (hereinafter referred to as "humidity sensor"), temperature sensors 6, 7 provided at upstream and downstream points in the flow direction, and ultrasonic transceivers (flow measurement sensors) 8a, 8b arranged to face each other obliquely with respect to the flow direction at upstream and downstream points in the flow direction.

[0032] In the following instructions, refer to Figure 2 , Figure 3 , Figure 4 A and Figure 4 In B, for example, the illustration of the pressure sensor 4, the humidity sensor 5, and the temperature sensors 6 and 7 and the illustration of their mounting holes are omitted.

[0033] As along Figure 1 The cross-sectional view taken along the plane A1-A2 shown in FIG. Figure 4 A and Figure 4As shown in B, the main flow path 9 to be measured is formed as a combination of the flow path main body 11 and the flow path cover 12 by inserting the raised portion 12a of the flow path cover 12 into the recessed side surface 11a of the flow path main body 11 in a state where the flat plate portion 12b of the flow path cover 12 with an upwardly convex shape abuts against the flow path main body 11 with an internal space 10 and a downwardly concave shape. In this state, the main flow path 9 is formed as a space left between the front end of the raised portion 12a of the flow path cover 12 and the internal space 10. Figure 3 , the space corresponding to the main flow path 9 is indicated by a single-point chain line.

[0034] In addition, Figure 4 In A, the secondary flow path 13 is a region surrounded by the groove 14 provided on the side surface of the raised portion 12 a of the flow path cover 12 and the recessed portion side surface 11 a of the flow path body 11 .

[0035] like Figure 4 As shown in A of FIG. 1 , the main flow path 9 for measuring the flow rate of the measured fluid has a rectangular cross section whose long side is indicated by the width W and whose short side is indicated by the height H. The multilayer portion 16 is formed by dividing the main flow path 9 into a plurality of layers using a partition plate 15 arranged substantially horizontally. The three-dimensional appearance of the main flow path 9 is as follows: Figure 3 shown.

[0036] like Figure 4 As shown in A, the short side height Ha of each of the multiple layers thus divided is less than the height H of the main flow path 9 that has not yet been divided. Each of the multiple layers of the multilayer portion 16 has a larger aspect ratio (W / Ha) than the main flow path 9 that has not yet been divided. This improves the two-dimensional distribution of the flow, thereby helping to make the flow velocity distribution more uniform along the width of the main flow path 9. In addition, making the height Ha of each short side of the multiple layers uniform also increases the degree of uniformity of the flow velocity distribution between the layers, thereby making it possible to rectify the flow as a whole.

[0037] like Figure 3 , Figure 5 A and Figure 5 As shown in FIG. 1B , the upstream portion of the secondary flow path 13 is connected to an upstream opening 17 disposed upstream of the main flow path 9, and the downstream portion of the secondary flow path 13 is connected to a downstream opening 18 disposed downstream of the main flow path 9. As can be seen, the secondary flow path 13 is located outside the main flow path 9 and is placed on the lower side relative to the main flow path 9 in the gravity direction.

[0038] In this structure, the secondary flow path 13 is provided as a bypass flow path with respect to the primary flow path 9 .

[0039] like Figure 5As shown in FIG. 1A , in the multilayer portion 16 , a pair of ultrasonic transceivers 8 a and 8 b are arranged to face each other obliquely so that ultrasonic waves travel through the flow of the measured fluid in the flow direction of the measured fluid. In addition, a portion of the upstream ultrasonic transceiver 8 a and a portion of the downstream ultrasonic transceiver 8 b are arranged to protrude into the multilayer portion 16.

[0040] exist Figure 5 In A, the dotted arrow M indicates the ultrasonic propagation path between the ultrasonic transceivers 8a, 8b. In the following description, the ultrasonic propagation path indicated by the dotted arrow M will sometimes be referred to as the "ultrasonic propagation path M" below. In order to make the ultrasonic transceivers 8a, 8b protrude into the flow of the measured fluid, the partition plate 15 is provided with a cutout 19, thereby preventing the ultrasonic transceivers 8a, 8b from abutting against any of the partition plates 15. In addition, in these cutouts 19, the size of the gap d between the front end of the ultrasonic transceivers 8a, 8b serving as ultrasonic transmitting / receiving parts and each partition plate 15 is set so that water droplets in the measured fluid fall without being aggregated, adhering due to surface tension, and stagnating at the front end of the ultrasonic transceivers 8a, 8b.

[0041] In addition, if Figure 1 As shown, various types of sensors such as temperature sensors 6, 7, pressure sensor 4 and humidity sensor 5 are arranged on the flow path portion 1 to measure the temperature, pressure and relative humidity of the measured fluid. These sensors and ultrasonic transceivers 8a, 8b are all installed on the flow path body 11.

[0042] like Figure 5 As shown in A, the temperature sensors 6 and 7 are arranged at upstream and downstream points on the ultrasonic propagation path M for measuring the flow velocity, and are arranged so that their average value corresponds to the temperature at the midpoint of the ultrasonic propagation path M. On the other hand, the pressure sensor 4 is arranged at the midpoint of the ultrasonic propagation path M to be adjacent to the outermost layer of the multilayer portion 16. However, due to the presence of the cutout 19, the fluid is allowed to pass smoothly inside the main flow path 9, thereby allowing the average pressure to be detected. In addition, the humidity sensor 5 is placed downstream of the multilayer portion 16. This arrangement is adopted so that the humidity sensor 5 performs measurements at a point where the humidity sensor 5 does not adversely affect (e.g., interferes with) the ultrasonic propagation path M and is significantly less affected by, for example, water droplets.

[0043] Next, refer to Figure 11 to explain the structure of the signal processing system. The control unit 20 is electrically connected to the ultrasonic transceivers 8a, 8b, and is configured to send and receive signals to and from the ultrasonic transceivers 8a, 8b. In addition, a signal processing unit 21 is provided to receive signals from the control unit 20 and perform flow calculation processing. The signal processing unit 21 not only sends and receives signals to and from the control unit 20, but also sends and receives signals to and from the pressure sensor 4, the humidity sensor 5, and the temperature sensors 6, 7. The signal processing unit 21 is electrically connected to these sensors to perform not only flow calculation processing but also various types of operation processing.

[0044] In this manner, the physical quantity measuring device 22 is constituted by the flow path section 1 , the control unit 20 , and the signal processing unit 21 .

[0045] Next, refer to Figure 5 A. Figure 5 B. Figure 6 and Figure 7 The secondary flow path 13 will be described in detail. Figure 6 and Figure 7 As shown, the height Hs and the width Ws of the secondary flow path 13 are set to dimensions that allow the secondary flow path 13 to have a volume large enough to hold a desired amount of water and allow the incoming water to flow smoothly without stagnation.

[0046] In addition, if Figure 5 As shown in A of FIG. 1 , the secondary flow path 13 is arranged to be located below the sensor cutout 19 of the partition plate 15. Figure 7 As shown, a communication portion 26 is provided to communicate the main flow path 9 with the secondary flow path 13. The communication portion 26 is configured so that water drops flowing down through the cutout 19 enter the secondary flow path 13 via the communication portion 26. As can be seen, the main flow path 9 is connected to the secondary flow path 13 via the communication portion 26.

[0047] Furthermore, the secondary flow path 13 is provided with narrowing portions 27, the gaps of these narrowing portions 27 having a dimension s, and the narrowing portions 27 are located Figure 6 , upstream and downstream of the connecting portion 26 in the area surrounded by the double-dot chain line G. As will be described in detail in the [1-2. Operation] section below, the gap size s is set so that the bypass flow (i.e., unmeasured flow) of the fluid passing through the secondary flow path 13 does not affect the measurement error regardless of whether any water droplets are contained in the secondary flow path 13, and is set so that the flow resistance relative to the liquid is minimized in the presence of any droplet flow. As used herein, the "gap size" refers to the size (length) measured from the bottom surface of the groove 14 to the side surface 11a of the recess of the flow path body 11.

[0048] Targeted Figure 5 The area surrounded by the double-dot chain line G shown in A of FIG. 1 illustrates the structure of the main flow path 9, the secondary flow path 13, the connecting portion 26 and the narrowing portion 27. These components are Figure 5 The area surrounded by the double-dot chain line J shown in A also has the same structure.

[0049] like Figure 2 As shown, in the present embodiment, the multilayer portion 16 has six layers formed by five partition plates 15. Next, how to assemble these partition plates 15 will be described.

[0050] like Figure 2 As shown, the raised portion 12a of the flow path cover 12 includes mounting portions 23, which are respectively provided at upstream and downstream points, and each mounting portion 23 has a screw hole for assembling the partition plate 15. Each partition plate 15 has a through hole (not shown) at each corner portion corresponding to the mounting portion 23. In a state where the partition plates 15 are sequentially stacked one on top of another via spacers 24 to leave a gap Ha between each pair of partition plates 15 vertically adjacent to each other, the partition plates 15 are fixed by tightening the screws inserted into the mounting portions 23.

[0051] The multilayer section 16 formed by assembling the partition plates 15 in this manner is mounted on the flow path cover 12 having a bulged shape. The flow path body 11 and the flow path cover 12 are integrated via the airtightly sealed rubber seal 25 to form the flow path section 1.

[0052] [1-2. Operation]

[0053] Next, how the physical quantity measuring device 22 having such a structure operates and functions will be described.

[0054] Will refer to Figure 3 First, the partition plates 15 are stacked one on top of another via the spacers 24 to leave a space between each pair of partition plates 15. Figure 4 The gap Ha shown in A of . Next, the partition plate 15 thus assembled is fixed to the mounting portion 23 by means of screws. The multilayer portion 16 formed by assembling the partition plates 15 in this manner is mounted on the raised portion 12a of the flow path cover 12. The flow path cover 12 is covered from above the flow path cover 12 by the flow path main body 11 having the downwardly concave internal space 10, thereby assembling the flow path portion 1 while ensuring an airtight seal by pressing the rubber seal 25. In this case, the space in which the multilayer portion 16 is placed will be used as the main flow path 9. In addition, referring to Figure 4In the cross-sectional view shown in FIG. 1A , the groove 14 provided on the side surface of the raised portion 12 a of the flow path cover 12 will be a region surrounded by the recessed side surface 11 a of the flow path body 11 and will serve as the auxiliary flow path 13 .

[0055] The secondary flow path 13 is connected to the primary flow path 9 via the communicating portion 26. The narrowed portions 27 are arranged upstream and downstream of the communicating portion 26, respectively.

[0056] Next, refer to Figure 3 , Figure 4 A. Figure 4 B. Figure 5 A and Figure 5 B is used to illustrate how the measured fluid flows.

[0057] exist Figure 3 In the embodiment, the measured fluid flows into the flow path section 1 through the fluid inlet 2 and flows out of the flow path section 1 through the fluid outlet 3. Specifically, the measured fluid flows through the flow path section 1 in the following manner.

[0058] First, the flow F of the measured fluid that has flowed into the flow path section 1 through the fluid inlet 2 having a tube shape is divided into a flow fs flowing toward the main flow path 9 implemented as the multilayer section 16 and a flow fm flowing toward the upstream opening 17 at the inlet space CH1 where the cross-sectional area in the flow direction increases. The flow fs flowing toward the main flow path 9 passes through the multilayer section 16 and then reaches the outlet space CH2.

[0059] On the other hand, the flow fm flowing into the upstream opening 17 passes through the secondary flow path 13 and then flows out through the downstream opening 18 to reach the outlet space CH2. The two flows fs, fm merge with each other in the outlet space CH2. Then, the merged flow flows out from the flow path section 1 through the fluid outlet 3. The positional relationship between the main flow path 9 and the secondary flow path 13 is Figure 4 A is illustrated as a cross section perpendicular to the flow direction, and Figure 5 B is illustrated as a cross section parallel to the flow direction.

[0060] like Figure 5 As shown in A of FIG. 1 , a pair of ultrasonic transceivers 8a, 8b are arranged relative to the flow of the main flow path 9, and as will be described later, the flow rate is measured by using these ultrasonic transceivers 8a, 8b. In addition, the pressure and temperature of the flow along the main flow path 9 are measured by the pressure sensor 4 and the temperature sensors 6, 7, respectively. The humidity is measured by the humidity sensor 5 located downstream of the portion where the flow rate is measured. As can be seen, the main flow path 9 is a flow path for measuring the physical quantity of the measured fluid. On the other hand, as can be seen from Figure 5 As can be seen from B, the secondary flow path 13 is a flow path provided as a bypass with respect to the primary flow path 9 and is not used for measuring any physical quantity.

[0061] Next, how liquid droplets such as water and water droplets behave when contained in a fluid to be measured will be described.

[0062] like Figure 3 and Figure 5 As shown in B, the flow path portion 1 is assembled to have a direction in which its horizontal or downstream portion is downward in the direction of gravity. Under such conditions, a portion of the water and droplets (hereinafter referred to as "bypass fluid") that flow in through the fluid inlet 2 together with the measured fluid falls due to gravity at the inlet space CH1 where the cross-sectional area increases, and flows into the secondary flow path 13 through the upstream opening 17. After that, the bypass fluid flows toward the downstream point inside the secondary flow path 13, and then flows out into the outlet space CH2 through the downstream opening 18 set at the downstream point. The bypass fluid then merges with the flow that has passed through the main flow path, and then flows out through the fluid outlet 3. In this case, the bypass fluid flowing through the secondary flow path 13 can easily merge with the flow along the main flow path due in part to the suction effect generated by the flow along the main flow path. In this way, the water and droplets that have flowed into the secondary flow path 13 can be bypassed without causing any interference to the measurement of physical quantities on the main flow path 9.

[0063] On the other hand, Figure 3 and Figure 5 In B, some of the droplets included in the water and droplets flowing in through the fluid inlet 2 together with the measured fluid do not fall due to gravity at the inlet space CH1 or do not flow into the secondary flow path 13 through the upstream opening 17. Such droplets flow into the multilayer portion 16 of the primary flow path 9.

[0064] Some of these droplets condense and gather on the partition plate 15, and flow toward a downstream point as a flowing liquid on the surface of the partition plate 15. At this time, other small droplets that have not condensed or gathered on the partition plate 15 are partially absorbed into the flowing liquid, thereby helping to further reduce the water and droplets contained in the measured fluid.

[0065] Next, refer to Figure 5 A and Figure 5 B is used to explain how to prevent water and liquid droplets flowing into the multilayer portion 16 from adhering to the ultrasonic transducers 8a, 8b.

[0066] By configuring the ultrasonic transducers 8a, 8b to protrude into the multilayer section 16, water and liquid droplets that have flowed on the surface of the multilayer section 16 become more likely to adhere to the ultrasonic transducers 8a, 8b. However, in the present embodiment, the partition plate 15 of the multilayer section 16 is provided with a cutout 19 that leaves a gap d between the ultrasonic transducers 8a, 8b. The gap d has a size that prevents water and liquid droplets from being gathered due to surface tension between the ultrasonic transmitting and receiving surfaces of the ultrasonic transducers 8a, 8b and the cutout 19. This greatly reduces the possibility that water and liquid droplets affect the transmitting and receiving surfaces by causing them to fall.

[0067] In this way, water and liquid droplets in the measured fluid flowing through the multilayer portion 16 serving as the measuring unit are significantly reduced to be ready for even more appropriate measurement. In addition, this can also reduce the possibility of degradation of the ultrasonic characteristics of the ultrasonic transceivers 8a, 8b that transmit and receive ultrasonic waves due to the accumulation of liquid droplets on the transmitting and receiving surfaces of the ultrasonic transceivers 8a, 8b.

[0068] Next, refer to Figure 7 to illustrate how such a droplet behaves.

[0069] First, a portion of the measured fluid flowing in through the fluid inlet 2 is introduced into the secondary flow path 13 through the upstream opening 17 provided upstream of the main flow path 9. The water contained in this portion of the measured fluid flows toward the downstream point as water droplets Ra. On the other hand, the droplets of the multilayer portion 16 flowing into the main flow path 9 and the water condensed on the partition plate 15 are gathered on the cutout 19, and fall as water droplets Rb through the connecting portion 26 due to gravity to reach the secondary flow path 13. In addition, the water that has attached to each front end of the flow measurement sensors 8a, 8b also falls as water droplets Rb through the connecting portion 26 due to gravity to reach the secondary flow path 13.

[0070] Such water droplets Ra and Rb merge with each other to form a water droplet Rc. The water droplet Rc flows through the secondary flow path 13 toward a downstream point, passes through the downstream opening 18, and then flows out through the fluid outlet 3.

[0071] In this case, if Figure 6 and Figure 7 As shown, the height Hs and width Ws of the secondary flow path 13, together with its length in the flow direction, are set to such dimensions that the expected amount of incoming water flows smoothly without stagnation, and the secondary flow path 13 has a volume large enough to prevent the incoming water from overflowing. In addition, the gap size s of the narrowing portion 27 is set so that the bypass flow rate of the fluid passing through the secondary flow path 13 (i.e., the flow rate of the measured fluid that is not measured) has a flow resistance that falls within a predetermined measurement error range without stagnation of water drops in the secondary flow path 13.

[0072] Figure 8 1 is a schematic top view illustrating the physical quantity measuring device 22 , in which the main flow path, the sub-flow path, and other components are simplified to make the flow of the measured fluid and water droplets easier to understand, in order to illustrate the flow operation of the constriction portion.

[0073] exist Figure 8 In the model flow path section 51 shown, for simplicity, only Figure 5 The lower side secondary flow path 13 of the two secondary flow paths 13 shown on the upper and lower sides of A is exemplified as the secondary flow path 54. Figure 8 For example Figure 5 The main flow path 9 shown in A is exemplified as the main flow path 53, Figure 5 The two narrowing portions 27 shown in A are exemplified as narrowing portions 59 and 60, and Figure 5 The connecting portion 26 shown in A is exemplified as the connecting portion 58. Figure 8 middle, Figure 5 The upstream opening 17 shown in B is exemplified as the upstream opening 55, and Figure 5 The downstream opening 18 shown in B is exemplified as the downstream opening 57. Figure 8 The gap between the middle constrictions 59 and 60 is illustrated as extending downward, but the gap is actually as shown in FIG. Figure 6 Horizontal extension shown.

[0074] The upstream side of the model flow path section 51 (with Figure 3 The inlet space 52 (corresponding to the area surrounded by the single-point chain line CH1 in FIG. 1 ) is connected to the main flow path 53 and the sub-flow path 54. The upstream portion of the sub-flow path 54 is connected to the inlet space 52 via an upstream opening 55.

[0075] The outlet space 56 on the downstream side of the model flow path portion 51 is connected to the main flow path 53 and the secondary flow path 54. The downstream portion of the secondary flow path 54 is connected to the downstream opening 57 (connected to the Figure 3 The exit space 56 corresponds to the area surrounded by the single-point chain line CH2.

[0076] The secondary flow path 54 is connected to the primary flow path 53 at the middle through a communication portion 58. Furthermore, the secondary flow path 54 includes narrowing portions 59, 60 upstream and downstream of the communication portion 58 thereof, respectively.

[0077] In such a structure, the flow F of the fluid to be measured flowing into the dummy flow path portion 51 is divided into a flow fs flowing into the main flow path 53 and a flow fm flowing into the sub-flow path 54 via the upstream opening 55 at the inlet space 52 .

[0078] The flow fs of the measured fluid passing through the main flow path 53 is detected by various sensors ( Figure 8The flow fm flowing into the secondary flow path 54 passes through the narrowing portions 59 and 60 to reach the outlet space 56.

[0079] Furthermore, the main flow path 53 and the sub-flow path 54 are connected to each other via the communication portion 58. Thus, some flows may be generated in the communication portion 58 depending on the conditions of the flows through the main flow path 53 and the sub-flow path 54.

[0080] In this way, a flow of the measured fluid is also generated in the secondary flow path 54, but no physical quantity measurement is performed on the secondary flow path 54. That is, the flow of the measured fluid through the secondary flow path 54 bypasses the main flow path 53 and constitutes a measurement error. If the error is always constant relative to the flow rate of the measured fluid through the main flow path 53, it is only necessary to take into account the proportion of the error to correct the error. However, the measured fluid as an object according to the present disclosure contains water droplets (water). If water droplets flow into the secondary flow path 54, the cross-sectional area of ​​the secondary flow path 54 changes. Depending on the specific circumstances, the secondary flow path 54 can be closed. This unexpected change in the flow rate of the bypass fluid flowing through the secondary flow path 54 (hereinafter referred to as "bypass flow") only constitutes a factor causing the measurement error.

[0081] In order to minimize such measurement errors, the flow difference (i.e., resistance difference) of the secondary flow path 54 depending on whether there are any water drops can be minimized by making the fluid resistance of the secondary flow path 54 as high as possible in the absence of water drops. Therefore, in order to create such a situation, the secondary flow path 54 is provided with narrowing portions 59, 60.

[0082] The constriction portion 59 is provided to impart a resistance effect to the bypass flow of the measured fluid flowing from the secondary flow path 54 to the main flow path 53 via the communication portion 58. On the other hand, the constriction portion 60 is provided to impart a resistance effect to the bypass flow of the measured fluid flowing from the main flow path 53 to the secondary flow path 54 via the communication portion 58.

[0083] In this way, by providing the narrowing portions 59, 60 upstream and downstream of the connecting portion 58, respectively, it is possible to reduce the change in the flow rate (or resistance) of the measured fluid through the secondary flow path 54 under any flow state depending on whether there are any water droplets, thereby helping to reduce measurement errors.

[0084] Next, refer to Figure 8 and Fig. 9 The resistance effect of the secondary flow path 54 is explained. When water droplets stagnate in the secondary flow path 54, it becomes difficult for flow to occur in the secondary flow path 54, which means that the possibility of causing an error is reduced. Therefore, in order to estimate the maximum error, it is advisable to consider a case where no water droplets stagnate in the secondary flow path 54.

[0085] exist Figure 8In the embodiment, the flow rate of the fluid flowing through the main flow path 53 is measured on the main flow path 53. In this case, the pressure difference between the area before the main flow path 53 and the area after the main flow path 53 is defined as ΔP. ​​That is, the pressure difference between the two areas upstream and downstream of the main flow path 53 is defined as ΔP. ​​In other words, the pressure difference ΔP is the difference between the pressure at the upstream opening 17 and the pressure at the downstream opening 18. In this case, due to the pressure difference ΔP, a flow is also generated inside the secondary flow path 54.

[0086] In this case, if the flow rates of the measured fluids F, fs and fm are Q, qs and qm respectively, these flow rates satisfy the following equation (1):

[0087] Q = qs + qm (1).

[0088] Since the measurement error is the flow rate qm of the fluid flowing through the secondary flow path 54, the following equation (2) for calculating the error flow rate qm is derived from equation (1):

[0089] qm = Q - qs (2).

[0090] exist Fig. 9 In FIG. 1 , the curve Gr1 represents the resistance curve of the flow F of the measured fluid that has flowed into the upstream opening 55 (17) (i.e., the flow F of the measured fluid along the flow path extending from the upstream opening 55 (17) through the downstream opening 57 (18)). That is, the flow path includes the upstream opening 55 (17), the downstream opening 57 (18), the main flow path 53 (9) and the secondary flow path 54 (13). On the other hand, Fig. 9 The graph Gr2 shown in FIG. 1 represents the flow resistance curve of the measured fluid fs flowing through the main flow path 53. Fig. 9 In the graphs Gr1 and Gr2 shown, the horizontal axis represents the flow rate, and the vertical axis represents the pressure difference.

[0091] If the flow rates of these flows at the pressure difference ΔP1 are Q1, qs1, and qm1, respectively, the error flow rate qm1 in this case is derived from the following equation (3) based on equation (2):

[0092] qm1 = Q1 - qs1 (3).

[0093] In this case, if the maximum error of flow measurement is defined as t%, the following inequality (4) is derived from equation (3):

[0094] qm1 / Q1 < t / 100 (4).

[0095] Therefore, the flow resistance of the secondary flow path 54 is determined so that its resistance curve satisfies the inequality (4). The resistance curve of the flow path is basically defined at the point where the flow path has the minimum cross-sectional area. Therefore, the resistance curve of the flow path depends to a large extent on, for example, Figure 8 The cross-sectional area of ​​the narrowing portions 59, 60 of the secondary flow path 54 shown. In other words, the resistance curve of the flow path depends largely on the gap size s. For example, by changing the gap size s and obtaining the flow path resistance of the secondary flow path 54 by simulation, the gap size s at which the flow path resistance of the secondary flow path 54 satisfies the above inequality (4) is determined. Once the gap size s is determined, the cross-sectional area of ​​the narrowing portions 59, 60 is also determined. The narrowing portions 59, 60 are formed based on the cross-sectional area of ​​the narrowing portions 59, 60 determined in this way. The cross-section of the narrowing portions 59, 60 may be rectangular or trapezoidal, whichever is appropriate. Alternatively, the cross-section of the narrowing portions 59, 60 may also have any other shape.

[0096] That is, the constricted portions 59, 60 (27) are formed based on the flow resistance that has been determined to satisfy the inequality (4).

[0097] Next, the measurement operation will be described. Figure 4 As shown in A of FIG. 1 , the main flow path 9 having a rectangular cross section is divided by a partition plate 15 to form a multilayer section 16 (in which each of the plurality of flow paths thus formed has an increased aspect ratio), thereby attempting to rectify the flow. This allows a stable flow to be maintained over a wide flow range from a low flow rate to a high flow rate. In such a state, as Figure 5 As shown, ultrasonic waves are transmitted and received through the ultrasonic propagation path M by ultrasonic transceivers 8a and 8b.

[0098] Such ultrasonic transmission and reception operations are performed by Figure 1 The control unit 20 shown in the figure performs. Based on the data thus acquired, the signal processing unit 21 can obtain the flow velocity V by the known reverse propagation time difference method. The flow rate Q of the measured fluid can be calculated by multiplying the flow velocity V by the flow path cross-sectional area S and further multiplying the product by the flow coefficient k used for correction. In other words, the flow rate Q can be calculated by the formula Q=k×V×S. At this time, using the pressure detected by the pressure sensor 4 and the temperature detected by the temperature sensors 6 and 7, the signal processing unit 21 can convert the calculated flow rate Q into a value under the standard state.

[0099] That is, the flow rate can be calculated based on the propagation time obtained by a pair of ultrasonic transceivers 8a, 8b by a known method. Then, the flow rate under the standard state can be obtained by correcting the value for temperature and pressure.

[0100] Next, the error involved in this flow measurement will be described.

[0101] When no water droplets are allowed to stagnate inside the secondary flow path 54, the secondary flow path 54 has a maximum flow rate. Therefore, the error is calculated in a state where no water droplets stagnate so that the maximum error is obtained. As described above, the resistance curve of the secondary flow path 54 is determined to satisfy inequality (4). This ensures that the error is less than a predetermined value t%.

[0102] In the following procedure, the hydrogen concentration of the measured fluid having humidity can be measured as an example of concentration measurement.

[0103] First, the water concentration Dw in the fluid is calculated using the relative humidity Tw provided by the relative humidity sensor 5, the temperature Td obtained as the average value of the temperatures detected by the temperature sensors 6, 7, and the pressure p provided by the pressure sensor 4. Next, the concentration of hydrogen with humidity can be obtained using the propagation time tdw from the upstream point to the downstream point, the propagation time tup from the downstream point to the upstream point provided by the ultrasonic transceivers 8a, 8b, the temperature Td provided by the temperature sensor, and the water concentration Dw calculated as described above.

[0104] [1-3. Advantages]

[0105] As can be seen from the above description, the physical quantity measuring device according to the typical embodiment includes: a main flow path 9; an upstream opening 17, which is provided upstream of the main flow path 9; a downstream opening 18, which is provided downstream of the main flow path 9; and a secondary flow path 13, which is provided outside the main flow path 9 so as to connect the upstream opening 17 and the downstream opening 18 to each other. The secondary flow path 13 is configured to have some narrowing portions 27 in a portion thereof.

[0106] This makes it possible to reduce the flow rate difference (i.e., resistance difference) caused by the difference in the passing cross-sectional area of ​​the secondary flow path depending on whether any water droplets are contained, even if water droplets are contained in the measured fluid flowing into the physical quantity measuring device 22. Therefore, this not only maintains sufficient accuracy when measuring the flow rate of gas in a high humidity environment, but also ensures a path for water droplets.

[0107] In addition, as in the above-described typical embodiment, the physical quantity measuring device 22 may be configured such that the flow measurement sensors 8a, 8b are arranged to protrude into the flow within the main flow path 9, and the physical quantity measuring device 22 may include a connecting portion 26 connected to the secondary flow path 13 from around the cutout 19 of the partition plate 15. The narrowing portion 27 of the secondary flow path 13 may be provided before and after the portion (connecting portion) connecting the secondary flow path 13 and the connecting portion 26 to each other. That is, the narrowing portion 27 may be provided between the upstream and downstream of the connecting portion connecting the secondary flow path 13 and the connecting portion 26 to each other.

[0108] This makes it possible that even in the case where fine water droplets flow into the main flow path 9 and collide with the flow measurement sensors 8a, 8b, these water droplets fall into the secondary flow path 13 through the communication portion 26 connected to the secondary flow path 13, thereby preventing water droplets from accumulating on the flow measurement sensors 8a, 8b and deterioration of measurement accuracy due to the attachment of water droplets. In addition, by providing the narrowing portion 27 between the upstream and downstream of the connection portion connecting the secondary flow path 13 and the communication portion 26 to each other, the flow rate can be appropriately controlled even at the portion of the secondary flow path 13 connected to the communication portion 26, thereby ensuring the flow measurement accuracy in the main flow path 9.

[0109] In addition, as in the above-described exemplary embodiment, the main flow path 9 of the physical quantity measuring device 22 may have a rectangular cross-sectional shape, and the physical quantity measuring device 22 may include a multilayer section 16 composed of partition plates 15 that divide the main flow path 9 into a plurality of layers. In this case, the flow measurement sensors 8a, 8b are arranged in the multilayer section 16.

[0110] This allows the distribution of the flow velocity and flow rate throughout the flow path to be evened out. Therefore, even if the flow measurement sensors 8a, 8b do not cover the entire flow path width, the flow rate can be measured highly accurately with good stability.

[0111] In addition, as in the above-described exemplary embodiment, the physical quantity measuring device 22 may further include temperature sensors 6, 7 for measuring the temperature of the fluid and a pressure sensor 4 for measuring the pressure of the fluid on the main flow path 9. The flow measurement sensors 8a, 8b, the temperature sensors 6, 7, and the pressure sensor 4 are electrically connected to the signal processing unit 21.

[0112] This enables the signal processing unit 21 to convert and measure the accurate flow rate of the fluid under standard conditions by receiving the flow signal of the measured fluid from the flow measurement sensors 8a, 8b, the accurate temperature of the measured fluid from the temperature sensors 6, 7, and the accurate pressure of the measured fluid from the pressure sensor 4.

[0113] In addition, as in the above-described exemplary embodiment, the flow measurement sensors 8a, 8b are a pair of ultrasonic transceivers 8a, 8b, and the physical quantity measuring device 22 may include a humidity sensor 5 for measuring the humidity of the fluid. The flow measurement sensors 8a, 8b, the temperature sensors 6, 7, the pressure sensor 4, and the humidity sensor 5 may be electrically connected to the signal processing unit 21.

[0114] This enables the flow velocity and flow rate to be determined by a known reverse propagation time difference method based on the ultrasonic propagation time for transmitting and receiving ultrasonic waves from a pair of ultrasonic transceivers 8a, 8b. In addition, this also enables the concentration of components other than water vapor contained in the fluid to be calculated by a known method based on the sound velocity obtained using the ultrasonic propagation time for transmitting and receiving ultrasonic waves from a pair of ultrasonic transceivers 8a, 8b, the measurement values ​​obtained by the temperature sensors 6, 7, and the measurement values ​​obtained by the humidity sensor 5.

[0115] In this way, the flow rate of the fluid and the concentration of the component contained in the fluid can be measured by preventing water droplets from intruding into the flow measurement unit (flow measurement sensors 8a, 8b).

[0116] The first embodiment has been described as a typical embodiment of the present disclosure. Note that the first embodiment described above is only an example of the present disclosure and should not be interpreted as restrictive. On the contrary, without departing from the scope of the present disclosure, the typical embodiment can be easily modified, replaced, provided with some additional components, or partially omitted. Alternatively, a new embodiment can be created by combining the various constituent elements described for the first embodiment in different ways.

[0117] Therefore, some other embodiments will be described as examples.

[0118] In the first embodiment described above, it is assumed that the multilayer part 16 assembles the partition plate 15 substantially horizontally. However, this is only an example and should not be construed as limiting. Alternatively, the partition plate 15 may also be assembled vertically. This allows a portion of the water droplets formed by the collision to flow down the partition plate more smoothly.

[0119] In the first embodiment described above, a pair of temperature sensors 6, 7 are respectively provided upstream and downstream of the flow path portion 1. If the fluid has a less steep temperature gradient, only one temperature sensor is sufficient. In this case, the cost can be reduced.

[0120] In the first embodiment described above, it is assumed that the pressure sensor 4 is placed on the outer layer side of the multilayer portion 16 in the height H direction. Alternatively, the pressure sensor 4 may also be placed in a plurality of layers facing the center of the multilayer portion 16 in the width W direction. In particular, the pressure sensor 4 is arranged on the signal processing unit 21 side, which makes it possible to miniaturize the signal processing unit 21 and reduce its cost by, for example, providing the pressure sensor 4 as an integral part of a control substrate serving as the signal processing unit 21 and / or simplifying interconnection wiring.

[0121] In the first embodiment described above, the physical quantity measuring device 22 is configured to use a pair of ultrasonic transceivers 8a, 8b as an exemplary flow measurement unit for measuring flow. However, this structure is only an example and should not be interpreted as limiting. Alternatively, the physical quantity measuring device 22 may also use a thermal sensor as an exemplary flow measurement unit. In this case, there is no need to provide a pair of thermal sensors. Thus, for example, instead of Figure 1 The ultrasonic transceiver 8a shown only requires the arrangement of a thermal sensor.

[0122] In the first embodiment described above, it is assumed that a pair of ultrasonic transceivers 8a, 8b and a humidity sensor are used as exemplary components for measuring concentration. Alternatively, a concentration sensor that can measure the concentration of a specific gas may also be used. In this case, instead of a pair of ultrasonic transceivers 8a, 8b or a thermal sensor and a humidity sensor used as flow measurement sensors, only the concentration sensor needs to be provided.

[0123] Furthermore, in the above-described exemplary embodiment, the multilayer portion 16 is formed by dividing the main flow path 9 into a plurality of layers using the partition plate 15. Of course, in the case where the partition plate 15 is not used, the main flow path 9 may have a single layer.

[0124] In the first embodiment described above, water droplets entering the measured fluid are described as a typical event. However, this is only an example and should not be interpreted as limiting. Even if any other liquid droplets enter the measured fluid instead of water droplets, the same or similar advantages can be achieved.

[0125] Note that the above embodiments are only examples of the present disclosure and should not be interpreted as limiting. On the contrary, without departing from the scope of the attached claims and their equivalents, each of these embodiments can be easily modified, replaced, provided with some additional components, or partially omitted in various ways.

[0126] (Summary)

[0127] As can be seen from the above description, the physical quantity measuring device (22) according to the first aspect includes a flow path body (11), a flow measurement unit (such as ultrasonic transceivers 8a, 8b, etc.), a signal processing unit (21), an upstream opening (17), a downstream opening (18) and a secondary flow path (13). The flow path body (11) includes a main flow path (9). The flow measurement unit is set for the main flow path (9). The signal processing unit (21) receives a signal from the flow measurement unit to measure the flow rate of the fluid. The upstream opening (17) is set upstream of the main flow path (9). The downstream opening (18) is set downstream of the main flow path (9). The secondary flow path (13) is set on the outside of the main flow path (9) so that the upstream opening (17) and the downstream opening (18) are connected to each other. The secondary flow path (13) has a narrowing portion (27) in the flow path for reducing the cross-sectional area of ​​the flow.

[0128] This aspect makes it possible not only to accurately measure the flow rate or concentration of the gas in a high humidity environment even if condensation droplets are contained in a fluid such as a gas, but also to ensure a path for the condensation droplets.

[0129] In the physical quantity measuring device (22) according to the second aspect, as in the first aspect, the flow measurement unit is arranged to protrude into the flow in the main flow path (9), and includes a communication portion (26) connected to the secondary flow path (13) from around the protruding portion of the flow measurement unit. The narrowing portion (27) is arranged before and after the portion connecting the secondary flow path (13) and the communication portion (26) to each other.

[0130] This aspect enables a resistance effect to be imparted to the measured fluid flowing through the bypass from the secondary flow path (13) via the connecting portion (26) toward the main flow path (9). In addition, this aspect also enables a resistance effect to be imparted to the measured fluid flowing through the bypass from the main flow path (9) via the connecting portion (26) toward the secondary flow path (13).

[0131] In the physical quantity measuring device (22) according to the third aspect, as in the first aspect or the second aspect, the main flow path (9) has a rectangular cross-sectional shape. The physical quantity measuring device (22) includes a multilayer section (16) composed of a partition plate (15) for dividing the main flow path (9) into a plurality of layers. The flow measurement unit is placed in the multilayer section (16).

[0132] This aspect enables the two-dimensional distribution of the fluid flowing through the main channel (9) to be improved, thereby helping to make the flow velocity distribution on the main channel (9) more uniform.

[0133] As in the first to third aspects, the physical quantity measuring device (22) according to the fourth aspect further includes a temperature sensor (6, 7) for measuring the temperature of the fluid and a pressure sensor (4) for measuring the pressure of the fluid on the main flow path (9). The signal processing unit (21) measures the flow rate of the fluid based on the signals received by the signal processing unit (21) from the flow measurement unit, the temperature sensor (6, 7) and the pressure sensor (4), respectively.

[0134] This aspect enables accurate measurement of the flow rate of the gas in a standard state in a high humidity environment even if condensation droplets are contained in the fluid such as gas.

[0135] As in the fourth aspect, the physical quantity measuring device (22) according to the fifth aspect further includes a humidity sensor (5) for measuring the humidity of the fluid. The flow measurement unit is a pair of ultrasonic transceivers (8a, 8b). The signal processing unit measures the flow rate and component concentration of the fluid based on the signals received by the signal processing unit from the flow measurement unit, the temperature sensor (6, 7), the pressure sensor (4) and the humidity sensor (5), respectively.

[0136] This aspect enables accurate measurement of the flow rate and concentration of a gas in a high humidity environment even if condensation droplets are contained in the fluid (such as a gas).

[0137] In the physical quantity measuring device (22) according to the sixth aspect, as in any one of the first to fifth aspects, the narrowing portion (27) is formed based on the flow resistance of the secondary flow path (13). The flow resistance of the secondary flow path (13) is defined as when a fluid that does not contain water flows through the flow path from the upstream opening (17) to the downstream opening (18), so that the quotient calculated by dividing the difference between the first flow rate (Q) and the second flow rate (qs) by the first flow rate is less than a predetermined value (t). The first flow rate (Q) is the flow rate of the fluid flowing through the flow path. The second flow rate (qs) is the flow rate of the fluid flowing through the main flow path (9). The fluid flows through the flow path and the main flow path (9) under a specified pressure difference (ΔP).

[0138] This aspect enables the error in flow rate measurement according to whether water droplets are contained to be kept below a predetermined value, thereby enabling the flow rate and concentration of the gas to be measured with high accuracy.

[0139] Industrial Applicability

[0140] Even in the case where water droplets are contained in the fluid (such as gas) flowing in, the present disclosure can reduce the difference in the cross-sectional area through which the gas passes and the measured flow rate change caused by whether condensed liquid droplets are contained. Therefore, the present disclosure is effectively applicable to a physical quantity measuring device that needs to measure not only the flow rate and concentration of the gas with good stability in a high humidity environment, but also ensure the path for water droplets. Specifically, the present disclosure is applicable not only to a device having both a flow meter and a component concentration measuring instrument, but also to a device having only a flow meter or a device having only a component concentration measuring instrument.

[0141] Description of Reference Numerals

[0142] 1Flow path part

[0143] 2 fluid inlet

[0144] 3 Fluid outlet

[0145] 4. Pressure sensor

[0146] 5Relative humidity sensor (humidity sensor)

[0147] 6 Temperature Sensor

[0148] 7 Temperature Sensor

[0149] 8a Ultrasonic transceiver (flow measurement sensor, flow measurement unit)

[0150] 8b ultrasonic transceiver (flow measurement sensor, flow measurement unit)

[0151] 9 Main Road

[0152] 10. Interior Space

[0153] 11Flow path main body

[0154] 11a Concave side

[0155] 12 Flow channel cover

[0156] 12a Raised part

[0157] 12b Flat plate

[0158] 13 Auxiliary flow path

[0159] 14 slots

[0160] 15 Divider

[0161] 16 Multilayer

[0162] 17 Upstream opening

[0163] 18 Downstream opening

[0164] 19 Incision

[0165] 20 Control unit

[0166] 21 Signal Processing Unit

[0167] 22 Physical quantity measuring device

[0168] 23 Installation

[0169] 24 Spacers

[0170] 25 Rubber seal

[0171] 26 Connecting part

[0172] 27 Constriction

[0173] 51 Model flow path section

[0174] 52 Entrance Space

[0175] 53 Main Road

[0176] 54 Auxiliary flow path

[0177] 55 Upstream opening

[0178] 56 Exit Space

[0179] 57 Downstream opening

[0180] 58 Connecting part

[0181] 59 Constriction

[0182] 60 Narrowing

[0183] CH1 Entrance Space

[0184] CH2 outlet space

Claims

1. A physical quantity measuring device, comprising: A flow path body, which includes a main flow path; A flow measurement unit, which is arranged for the main flow path; a signal processing unit configured to receive a signal from the flow measurement unit to measure a flow rate of a fluid; an upstream opening, which is arranged upstream of the main flow path; a downstream opening disposed downstream of the main flow path; as well as a secondary flow path provided outside the primary flow path so as to connect the upstream opening and the downstream opening to each other, The secondary flow path has a narrowing portion for reducing a cross-sectional area of ​​the flow path.

2. The physical quantity measuring device according to claim 1, wherein: The flow measurement unit is arranged to protrude into the flow in the main flow path, and includes a communication portion connected to the sub-flow path from around the protruding portion of the flow measurement unit, and The narrowed portion is arranged before and after a location connecting the secondary flow path and the communication portion to each other.

3. The physical quantity measuring device according to claim 1 or 2, wherein: The main flow path has a rectangular cross-sectional shape, The physical quantity measuring device includes a multilayer section formed of a partition plate for dividing the main flow path into a plurality of layers, and The flow measurement unit is placed in the multi-layer portion.

4. The physical quantity measuring device according to any one of claims 1 to 3, comprising a temperature sensor and a pressure sensor on the main flow path, wherein the temperature sensor is configured to measure the temperature of the fluid, and the pressure sensor is configured to measure the pressure of the fluid. in, The signal processing unit is configured to measure a flow rate of the fluid based on signals that the signal processing unit receives from the flow measurement unit, the temperature sensor, and the pressure sensor, respectively.

5. The physical quantity measuring device according to claim 4, further comprising a humidity sensor configured to measure the humidity of the fluid. in, The flow measurement unit is a pair of ultrasonic transceivers, and The signal processing unit is configured to measure a flow rate and a component concentration of the fluid based on signals received by the signal processing unit from the flow measurement unit, the temperature sensor, the pressure sensor, and the humidity sensor, respectively.

6. The physical quantity measuring device according to any one of claims 1 to 5, wherein: The narrowing portion is formed based on the flow resistance of the secondary flow path, and The flow resistance of the secondary flow path is defined as a condition in which a fluid not containing water flows through the flow path from the upstream opening to the downstream opening, so that a quotient calculated by dividing a difference between a first flow rate and a second flow rate by the first flow rate is less than a predetermined value, wherein the first flow rate is a flow rate of the fluid flowing through the flow path, the second flow rate is a flow rate of the fluid flowing through the main flow path, and the fluid flows through the flow path and the main flow path under a specified pressure difference.

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