Physical quantity measurement device

Abstract

The purpose of the present disclosure is to provide a physical quantity measurement device that can stably measure gas flow rate or gas component concentration even in a highly humid environment in which the fluid to be measured contains water droplets. The physical quantity measurement device (22) comprises a flow path main body (11), a flow rate measurement unit, an upstream opening part (17) , a downstream opening part (18), and an auxiliary flow path (13). The flow path main body (11) has a main flow path (9). The flow rate measurement unit is provided in the main flow path (9). The upstream opening part (17) is provided at the upstream side of the main flow path (9). The downstream opening part(18) is provided at the downstream side of the main flow path (9). The auxiliary flow path (13) is provided on the outer side of the main flow path (9) and connects the upstream opening part (17) to the downstream opening part (18). The auxiliary flow path (13) has a constricting part (27) that constricts the flow path cross section in the flow path.

Description

Physical Quantity Measuring Devices

[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 a gas by removing the influence of water droplets and the like from a fluid containing water.

[0002] Patent Document 1 discloses a physical quantity measuring device that measures the flow rate of a fluid or the concentration of a component contained in the fluid by removing the effects of water droplets and the like from the fluid containing water. In this measuring device, the fluid to be measured is divided into a main flow path that measures the physical quantity and a sub-flow path that bypasses the main flow path and does not measure the physical quantity, and then the two flows merge again downstream. At this time, water droplets contained in the fluid to be measured flow away via the sub-flow path.

[0003] Japanese Patent Application Laid-Open No. 2022-25751

[0004] The object of the present disclosure is to provide a physical quantity measuring device that can accurately measure gas flow rate and gas concentration in a high humidity environment, even when the incoming flow contains condensation droplets, while also ensuring a path for the condensation droplets.

[0005] The physical quantity measuring device according to the present disclosure comprises a flow path main body, a flow rate measuring unit, a signal processing unit, an upstream opening, a downstream opening, and a sub-flow path. The flow path main body has a main flow path. The flow rate measuring unit is provided in the main flow path. The signal processing unit receives a signal from the flow rate measuring unit and measures the flow rate of a fluid. The upstream opening is provided upstream of the main flow path. The downstream opening is provided downstream of the main flow path. The sub-flow path is provided outside the main flow path and connects the upstream opening and the downstream opening. The sub-flow path has a constriction portion in the flow path that narrows the cross section of the flow path.

[0006] FIG. 1 is a configuration diagram of a flow measurement device including an external perspective view of a flow path section according to a first embodiment. FIG. 2 is an exploded assembly diagram of the flow path section of FIG. 1 according to the first embodiment. FIG. 3 is an exploded assembly diagram showing a partial cross section of the flow path section of FIG. 1 according to the first embodiment. FIG. 4A is a schematic diagram showing the A1-A2 cross section of the flow path section of FIG. 1 according to the first embodiment. FIG. 4B is an exploded assembly diagram of the flow path section of FIG. 1 according to the first embodiment. FIG. 5A is a B1-B2 cross section of the flow path section of FIG. 1 according to the first embodiment. FIG. 5B is a schematic diagram of the C1-C2 cross section of FIG. 5A. FIG. 6 is an enlarged plan view of the throttle section at part G of FIG. 5A in the A1-A2 cross section of FIG. 4 according to the first embodiment. FIG. 7 is a schematic diagram showing the D1-D2 cross section of the throttle section of FIG. 6 according to the first embodiment. FIG. 8 is a diagram illustrating the flow operation of the throttle section according to the first embodiment. FIG. 9 is a graph showing the resistance curve of the flow of the fluid to be measured in the flow path and the resistance curve of the fluid to be measured in the main flow path according to the first embodiment. FIG. 10 is a partial cross-sectional view of a flow path portion of a conventional physical quantity measuring device.

[0007] (Knowledge, etc., that Forms the Basis of the Present Disclosure) At the time the inventors arrived at the present disclosure, a physical quantity measuring device 100 shown in FIG. 10 existed as an apparatus for measuring a physical quantity, such as the flow rate of a gas containing moisture, and for forming a sub-channel for removing water droplets from a fluid to be measured. FIG. 10 is a partial cross-sectional view of a channel portion of the physical quantity measuring device 100. In this configuration, the fluid to be measured is divided into a main channel 105 that measures the physical quantity and a sub-channel 104 that bypasses the main channel and does not measure the physical quantity, and then the two channels reunite downstream. Water droplets contained in the fluid to be measured flow away via the sub-channel 104.

[0008] The sub-channel 104 constructed in this manner had dimensions of width W1 and height F, which were generally configured to be sufficient to allow the required amount of water droplets to stay and flow.

[0009] However, the inventors discovered that this method has the problem that the presence or absence of water droplets causes a large change in flow rate (change in resistance) in the bypass of the measured fluid that passes through the secondary flow path 104, resulting in errors in measurement accuracy.In order to solve this problem, the inventors have come up with the subject matter of the present disclosure.

[0010] Therefore, the physical quantity measuring device of the present disclosure includes a flow path main body, a flow rate measuring unit, a signal processing unit, an upstream opening, a downstream opening, and a sub-flow path. The flow path main body has a main flow path. The flow rate measuring unit is provided in the main flow path. The signal processing unit receives a signal from the flow rate measuring unit and measures the flow rate of the fluid. The upstream opening is provided upstream of the main flow path. The downstream opening is provided downstream of the main flow path. The sub-flow path is provided outside the main flow path and connects the upstream opening and the downstream opening. The sub-flow path has a constriction portion in the flow path that narrows the flow path cross section. This reduces the change in flow rate (change in resistance) of the flow passing through the sub-flow path due to the presence or absence of water droplets in the sub-flow path, thereby reducing measurement errors. Note that "outside the main flow path" where the sub-flow path is provided refers to a space other than the space in which the main flow path is formed.

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters or redundant description of substantially the same configuration may be omitted.

[0012] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0013] First Embodiment Hereinafter, a first embodiment will be described with reference to FIGS.

[0014] [1-1. Configuration] FIG. 1 is a configuration diagram of a flow measurement device including an external perspective view of a flow path section according to a first embodiment of the present disclosure. FIG. 2 is an exploded assembly view of the flow path section in FIG. 1. FIG. 3 is an exploded assembly view showing a partial cross section of the flow path section in FIG. 1. FIGS. 4A and 4B are a schematic diagram and an exploded view showing the A1-A2 cross section of the flow path section in FIG. 1. FIGS. 5A and 5B are a B1-B2 cross section and a C1-C2 cross section of the flow path section in FIG. 1. FIG. 6 is an enlarged plan view of the throttling section at section G in FIG. 5A. FIG. 7 is a D1-D2 cross section of the throttling section in FIG. 6. FIG. 8 is an explanatory diagram of the flow operation of the throttling section. FIG. 9 is a graph showing the resistance curve of the flow of the fluid to be measured in the flow path and the resistance curve of the flow of the fluid to be measured in the main flow path.

[0015] 1, a flow path section 1 has a fluid inlet 2 through which a fluid to be measured (fluid) flows in and a fluid outlet 3 through which the fluid to be measured flows out. The flow path section 1 also has a pressure sensor 4, a relative humidity sensor 5 (hereinafter referred to as a humidity sensor), temperature sensors 6 and 7 provided upstream and downstream in the flow direction, and ultrasonic transmitter-receivers (flow rate measurement sensors) 8a and 8b arranged upstream and downstream in the flow direction, facing each other at an angle to the flow direction.

[0016] 2, 3, 4A and 4B, the pressure sensor 4, humidity sensor 5, temperature sensors 6 and 7 and their mounting holes are omitted.

[0017] 4A and 4B, which are cross sections taken along the line A1-A2 in Fig. 1, the main flow path 9 in which measurement is performed is formed by inserting the convex portion 12a of the flow path cover 12, which has an upwardly convex shape, into the recessed side surface 11a of the flow path main body 11, which has an internal space 10 with a downwardly concave shape, and by assembling the convex portion 12a so that the flat portion 12b of the flow path cover 12 abuts against the flow path main body 11, in a space formed between the tip of the convex portion 12a of the flow path cover 12 and the internal space 10. The space corresponding to the main flow path 9 is shown by a dashed line in Fig. 3.

[0018] In FIG. 4A , the sub-channel 13 is an area surrounded by the groove 14 provided on the side surface of the convex portion 12 a of the channel cover 12 and the side surface 11 a of the concave portion of the channel body 11 .

[0019] As shown in Fig. 4A, the main flow path 9, in which the flow rate of the fluid to be measured is measured, has a rectangular cross section with a long side having a width W and a short side having a height H, and the main flow path 9 is divided into multiple layers by partition plates 15 arranged in a substantially horizontal direction to form a multi-layer section 16. The three-dimensional appearance is as shown in Fig. 3.

[0020] 4A , the height Ha of the short side of each divided layer is smaller than the height H before division, and the aspect ratio (W / Ha) of each layer of the multilayer section 16 is larger than before division, which improves the two-dimensionality of the flow and uniforms the flow velocity distribution in the width direction of the main flow channel 9. Furthermore, by making the height Ha of the short side of each layer equal, the uniformity of the flow velocity distribution in each layer is also improved, and overall flow straightening is achieved.

[0021] 3, 5A, and 5B, the upstream side of the sub-channel 13 is connected to an upstream opening 17 that opens to the upstream side of the main channel 9, and the downstream side is connected to a downstream opening 18 that opens to the downstream side of the main channel 9. In this way, the sub-channel 13 is located outside the main channel 9 and is disposed below the main channel 9 in the direction of gravity.

[0022] With this configuration, the sub-flow passage 13 is configured as a flow passage that bypasses the main flow passage 9 .

[0023] 5A, in the multilayer section 16, a pair of ultrasonic transmitter-receivers 8a, 8b are disposed diagonally opposite each other with respect to the direction of flow of the fluid to be measured so that ultrasonic waves cross the flow. In addition, a part of the upstream ultrasonic transmitter-receiver 8a and a part of the downstream ultrasonic transmitter-receiver 8b are disposed so as to protrude into the multilayer section 16.

[0024] The dashed line M in Fig. 5A indicates the ultrasonic propagation path between the ultrasonic transmitters and receivers 8a and 8b. Hereinafter, the dashed line M may be referred to as the ultrasonic propagation path M. In order to allow the ultrasonic transmitters and receivers 8a and 8b to protrude into the flow of the fluid to be measured, a notch 19 is provided in the partition plate 15 to prevent the ultrasonic transmitters and receivers 8a and 8b from contacting the partition plate 15. In addition, in the notch 19, the gap d between the tips of the ultrasonic transmitters and receivers 8a and 8b and the partition plate 15 is sized so that water droplets in the fluid to be measured accumulate and adhere due to surface tension, dripping off the tips of the ultrasonic transmitters and receivers 8a and 8b without remaining on the tips.

[0025] As shown in FIG. 1, various sensors such as temperature sensors 6 and 7, a pressure sensor 4, and a humidity sensor 5 are arranged in the flow path section 1 to measure the temperature, pressure, and relative humidity of the fluid to be measured, and all of these are attached to the flow path main body 11, just like the ultrasonic transmitter / receivers 8a and 8b.

[0026] 5A, the temperature sensors 6 and 7 are located upstream and downstream of the ultrasonic propagation path M where the flow velocity is measured, and are arranged so that their average value corresponds to the temperature at the center of the ultrasonic propagation path M. The pressure sensor 4 is located on the outermost layer of the multilayer section 16 at the center of the ultrasonic propagation path M, but the main flow path 9 is connected internally by the presence of the notch 19, so that an average pressure can be obtained. The humidity sensor 5 is located downstream of the multilayer section 16. This allows the humidity sensor 5 to perform measurements at a position where it is not affected by turbulence in the ultrasonic propagation path M and is less affected by water droplets, etc.

[0027] Next, the configuration of the signal processing system will be explained using Figure 1. The control unit 20 is electrically connected to the ultrasonic transmitter / receivers 8a and 8b, and is configured to be able to send and receive signals thereto. Also provided is a signal processing unit 21 that receives signals from the control unit 20 and performs flow rate calculation processing. This signal processing unit 21 not only sends and receives signals from the control unit 20, but also signals from the pressure sensor 4, humidity sensor 5, and temperature sensors 6 and 7, and is electrically connected to these sensors, so that it not only performs the above flow rate calculation processing but also various other arithmetic processing.

[0028] In this way, the flow path section 1, the control section 20, and the signal processing section 21 constitute a physical quantity measuring device 22.

[0029] Next, details of the sub-channel 13 will be described with reference to Figures 5A, 5B, 6 and 7. As shown in Figures 6 and 7, the height Hs and width Ws of the sub-channel 13 are sized to have a volume sufficient to accommodate an expected amount of water and to allow the inflowing water to flow without stagnation.

[0030] 5A, the secondary flow path 13 is positioned below the sensor cutout 19 of the partition plate 15, and a communication section 26 is provided to communicate the main flow path 9 and the secondary flow path 13, as shown in FIG. 7. The communication section 26 is configured so that water droplets dripping from the cutout 19 enter the secondary flow path 13 through the communication section 26. In this way, the main flow path 9 is connected to the secondary flow path 13 via the communication section 26.

[0031] In addition, in this sub-channel 13, throttle sections 27 with a gap dimension s are provided on the upstream and downstream sides of the communication section 26 within the area surrounded by the two-dot chain line G in Figure 6. As will be described in detail in the section "1-2. Operation" below, this gap dimension s is set so that the bypass flow rate (unmeasured flow rate) passing through the sub-channel 13 does not affect measurement errors, regardless of the presence or absence of water droplets in the sub-channel 13, and so that flow resistance to the liquid is small when droplets are flowing. Here, the gap dimension is the length (dimension) from the bottom surface of the groove 14 to the side surface 11a of the recess in the channel main body 11.

[0032] The configurations of the main flow path 9, the sub-flow path 13, the communication section 26, and the throttle section 27 have been described above in the area surrounded by the two-dot chain line G in Figure 5A, but the area surrounded by the two-dot chain line J in Figure 5A also has a similar configuration.

[0033] As shown in FIG. 2, in this embodiment, the multi-layer section 16 is divided into six layers by five partition plates 15, and the assembly structure of these partition plates 15 will be described next.

[0034] 2, the convex portion 12a of the flow path cover 12 is provided with mounting portions 23 having screw holes on the upstream and downstream sides for assembling the partition plates 15. The partition plates 15 are provided with through holes (not shown) at locations corresponding to the mounting portions 23, and are fixed to the mounting portions 23 with screws in a state where they are stacked one on top of the other using spacers 24 so that the interval between the upper and lower partition plates 15 is Ha.

[0035] The multilayer portion 16 formed by assembling the partition plate 15 in this manner is attached to the convex-shaped flow path cover 12. The flow path main body 11 is integrated with the flow path cover 12 via a packing 25 that provides an airtight seal, thereby forming the flow path portion 1.

[0036] [1-2. Operation] The operation and function of the physical quantity measuring device 22 configured as above will be described below.

[0037] The assembly procedure for the flow path section 1 will be described with reference to FIG. 3 . First, the partition plates 15 are stacked and assembled in order via spacers 24 so that the spacing between them is equal to Ha shown in FIG. 4A , and then secured to the mounting section 23 with screws. The multilayer section 16 formed by assembling the partition plates 15 in this manner is attached to the convex section 12a of the flow path lid 12. The flow path body 11 having the downwardly recessed internal space 10 is placed over the flow path lid 12, and the flow path section 1 is assembled by pressing the packing 25 to ensure an airtight seal. At this time, the space in which the multilayer section 16 is disposed becomes the main flow path 9. Furthermore, in the cross-sectional view of FIG. 4A , the groove 14 provided on the side surface of the convex section 12a of the flow path lid 12 becomes the area surrounded by the recessed side surface 11a of the flow path body 11, and this portion becomes the sub-flow path 13.

[0038] The sub-flow passage 13 is connected to the main flow passage 9 via a communication section 26 , and throttle sections 27 are arranged on the upstream side and downstream side of the communication section 26 .

[0039] Next, the flow of the fluid to be measured will be described with reference to FIGS. 3, 4A, 4B, 5A and 5B.

[0040] 3, the fluid to be measured flows in through a fluid inlet 2 and flows out through a fluid outlet 3. The process during this period will be described in detail below.

[0041] That is, the flow F of the fluid to be measured that flows in from the pipe-shaped fluid inlet 2 is divided into a flow fs toward the main flow path 9 formed by the multilayer portion 16 and a flow fm toward the upstream opening 17 in the inlet space portion CH1 where the cross-sectional area in the flow direction is expanded. The flow toward the main flow path 9 passes through the multilayer portion 16 and then reaches the outlet space portion CH2.

[0042] On the other hand, the flow fm that has flowed into the upstream opening 17 passes through the sub-channel 13, then flows out from the downstream opening 18 and reaches the outlet space CH2. The two flows fs and fm join in the outlet space CH2, and the joined flows flow out from the fluid outlet 3. Figure 4A shows the positional relationship between the main channel 9 and the sub-channel 13 in a cross section perpendicular to the flow direction, and Figure 5B shows it in a cross section parallel to the flow direction.

[0043] As shown in Figure 5A, a pair of ultrasonic transmitters and receivers 8a and 8b are arranged relative to the flow in the main flow path 9, and these are used to measure the flow rate, as described below. In addition, the pressure sensor 4 and temperature sensors 6 and 7 measure the pressure and temperature of the flow in the main flow path 9, respectively. The humidity sensor 5 on the downstream side measures humidity. In this way, the main flow path 9 is a flow path that measures the physical quantity of the fluid to be measured. On the other hand, as can be seen in Figure 5B, the sub-flow path 13 is a flow path that bypasses the main flow path 9, and no physical quantity is measured in the sub-flow path 13.

[0044] Next, the behavior of these components when the fluid to be measured contains water or droplets such as water droplets will be described.

[0045] As shown in Figures 3 and 5B, the flow path section 1 is installed horizontally or with the downstream side facing downward in the direction of gravity. Under these conditions, some of the moisture and droplets (hereinafter referred to as "bypass fluid") flowing in with the fluid to be measured from the fluid inlet 2 drips downward due to gravity in the inlet space CH1 with an expanded cross-sectional area and flows into the secondary flow path 13 from the upstream opening 17. The bypass fluid then flows downstream in the secondary flow path 13, flows out of the outlet space CH2 from the downstream opening 18 provided on the downstream side, merges with the flow that has passed through the main flow path, and flows out of the fluid outlet 3. At this time, the bypass fluid flowing in the secondary flow path 13 can easily merge with the flow in the main flow path due to the attraction effect of the mainstream flow. As described above, the moisture and droplets that flow into the secondary flow path 13 are bypassed without interfering with the measurement of physical quantities in the main flow path 9.

[0046] On the other hand, in Figures 3 and 5B, among the moisture and droplets that flow in from the fluid inlet 2 along with the fluid to be measured, those that do not drip downward due to gravity in the inlet space CH1 and do not flow into the secondary flow path 13 from the upstream opening 17 flow into the multilayer section 16 of the main flow path 9.

[0047] Some of these droplets aggregate and adhere to the partition plate 15 and flow downstream as a flowing liquid on the surface of the partition plate 15. At this time, some of the fine droplets that do not aggregate and adhere to the partition plate are absorbed into the flowing liquid, thereby further reducing the moisture and droplets in the fluid to be measured.

[0048] Next, measures to prevent moisture or droplets that have flowed into the multilayer portion 16 from adhering to the ultrasonic transmitter / receivers 8a and 8b will be described with reference to FIGS. 5A and 5B.

[0049] Because the ultrasonic transmitters and receivers 8a and 8b are configured to protrude into the multilayer section 16, moisture and liquid droplets that have flowed along the surface of the multilayer section 16 tend to adhere to them. However, the partition plate 15 of the multilayer section 16 is provided with a notch 19, which provides a gap d between the ultrasonic transmitters and receivers 8a and 8b and the notch 19. This gap d is sized to prevent accumulation due to surface tension between the ultrasonic transmitting and receiving surfaces of the ultrasonic transmitters and receivers 8a and 8b and the notch 19, so moisture and liquid droplets do not drip downward and affect the transmitting and receiving surfaces.

[0050] In this way, the fluid to be measured flowing through the multilayer portion 16, which is the measurement portion, is reduced in moisture and droplets, making it suitable for measurement. In addition, deterioration of ultrasonic characteristics due to droplets adhering to the transmitting and receiving surfaces of the ultrasonic transmitters and receivers 8a and 8b that transmit and receive ultrasonic waves is prevented.

[0051] The droplet behavior described above is shown in FIG.

[0052] First, the moisture contained in the fluid to be measured that flows into the sub-channel 13 from the upstream opening 17 provided on the upstream side of the main channel 9, among the fluid to be measured that flows in from the fluid inlet 2, becomes water droplets Ra and flows downstream. In addition, the liquid droplets that flow into the multilayer portion 16 of the main channel 9 and the moisture condensed on the partition plate 15 adhere to the cutout portion 19 and drip down the communicating portion 26 as water droplets Rb due to gravity, reaching the sub-channel 13. In addition, the moisture that has adhered to the tips of the flow rate measuring sensors 8a and 8b also drip down the communicating portion 26 as water droplets Rb due to gravity, reaching the sub-channel 13.

[0053] The water droplets Ra and Rb merge to form water droplets Rc, which flow downstream in the sub-flow passage 13 , flow out from the downstream opening 18 , and then flow out from the fluid outlet 3 .

[0054] 6 and 7, the height Hs and width Ws of the sub-passage 13 are set to allow the water to flow without stagnation even when an expected amount of water flows in, and the volume to accommodate the water that flows in, combined with the length in the flow direction, is secured. Also, the gap dimension s of the throttle section 27 is set so that when no water droplets are stagnated in the sub-passage 13, the bypass flow rate (the flow rate of the fluid to be measured that is not measured) that passes through the sub-passage 13 is a flow resistance that falls within a predetermined measurement error range.

[0055] FIG. 8 is a diagram illustrating the flow operation of the throttle section, showing a schematic representation of the physical quantity measuring device 22 as viewed from above with the main flow path, sub-flow paths, etc. simplified to make it easier to understand the flow of the fluid to be measured and the water droplets.

[0056] In the model flow path portion 51 shown in Fig. 8, for simplification, of the two sub-flow paths 13 at the top and bottom of the drawing in Fig. 5A, only the lower sub-flow path 13 is depicted as a sub-flow path 54. Also, in Fig. 8, for example, the main path 9 shown in Fig. 5A is depicted as a main path 53, the two throttling portions 27 are depicted as throttling portions 59 and 60, and the communicating portion 26 is depicted as a communicating portion 58. Furthermore, in Fig. 8, the upstream opening 17 shown in Fig. 5B is depicted as an upstream opening 55, and the downstream opening 18 is depicted as a downstream opening 57. Although the gap between the throttling portions 59 and 60 is depicted as pointing downward, it is actually horizontal as shown in Fig. 6.

[0057] An inlet space 52 (corresponding to the area surrounded by the dashed-dotted line CH1 in FIG. 3 ) located upstream of the model flow path 51 is connected to the main flow path 53 and the sub-flow path 54. The upstream side of the sub-flow path 54 is connected to the inlet space 52 via an upstream opening 55.

[0058] An outlet space 56 located downstream of the model flow path 51 is connected to the main flow path 53 and the sub-flow path 54. The downstream side of the sub-flow path 54 is connected to the outlet space 56 (corresponding to the area surrounded by the dashed line CH2 in FIG. 3 ) via a downstream opening 57.

[0059] The secondary flow passage 54 communicates with the main flow passage 53 at its midpoint via a communication section 58. The secondary flow passage 54 also has a throttle section 59 on the upstream side of the communication section 58 and a throttle section 60 on the downstream side.

[0060] In this configuration, the measured flow F flowing into the model flow path section 51 is divided into a flow fs flowing into the main flow path 53 at the inlet space section 52 and a flow fm flowing into the secondary flow path 54 at the upstream opening 55.

[0061] The flow fs of the fluid to be measured passing through the main flow path 53 reaches the outlet space 56 after the physical quantities of the flow are measured by various sensors (not shown in FIG. 8 ) arranged in the main flow path 53. On the other hand, the flow that has flowed into the sub-flow path 54 as the flow fm reaches the outlet space 56 through the throttle sections 59 and 60.

[0062] Furthermore, since the main flow path 53 and the sub-flow path 54 are connected via a communication part 58 , a flow is also generated in the communication part 58 depending on the flow conditions in the main flow path 53 and the sub-flow path 54 .

[0063] In this way, a flow of the fluid to be measured also occurs in the secondary flow path 54, but no physical quantity is measured in this flow path. In other words, the flow of the fluid to be measured passing through the secondary flow path 54 bypasses the main flow path 53, and this flow results in a measurement error. If this error were always constant relative to the flow rate of the fluid to be measured in the main flow path 53, it would be sufficient to correct it by taking into account that ratio. However, the fluid to be measured in this disclosure contains water droplets (moisture), and when these water droplets flow into the secondary flow path 54, the cross-sectional area of ​​the secondary flow path 54 changes. In some cases, the secondary flow path 54 may become closed. This unpredictable change in the flow rate of the bypass fluid flowing through the secondary flow path 54 (hereinafter referred to as the bypass flow rate) is a factor that causes a measurement error.

[0064] In order to minimize such measurement errors, the fluid resistance of the sub-passage 54 in the absence of water droplets should be increased as much as possible, thereby minimizing the difference in flow rate (difference in resistance) between the presence and absence of water droplets in the sub-passage 54. To achieve this state, the sub-passage 54 is provided with throttle sections 59 and 60.

[0065] The throttle portion 59 is intended to provide a resistance effect to the bypass flow of the fluid to be measured that flows from the sub-channel 54 via the communicating portion 58 to the main channel 53. The throttle portion 60 is intended to provide a resistance effect to the bypass flow of the fluid to be measured that flows from the main channel 53 via the communicating portion 58 to the sub-channel 54.

[0066] In this way, by providing the throttle sections 59 and 60 respectively upstream and downstream of the communication section 58, the change in flow rate (change in resistance) of the fluid to be measured passing through the secondary flow path 54, which is caused by the presence or absence of water droplets, can be reduced regardless of the flow state, thereby reducing measurement errors.

[0067] Next, the resistance effect of the sub-flow path 54 will be described with reference to Figures 8 and 9. If water droplets remain in the sub-flow path 54, it is difficult for the water to flow into the sub-flow path 54, which means that errors are less likely to occur. Therefore, in order to estimate the maximum error, it is best to consider the case where no water droplets remain in the sub-flow path 54.

[0068] 8, the flow rate through the main flow path 53 is measured. The pressure difference between the upstream and downstream sides of the main flow path 53 is designated ΔP. In other words, the pressure difference between the upstream and downstream sides of the main flow path 53 is designated 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. At this time, a flow in the sub-flow path 54 is also generated by the pressure difference ΔP.

[0069] Here, when the flow rates of the flows F, fs, and fm of the fluid to be measured are respectively Q, qs, and qm, the relationship of the following Equation 1 holds between these flow rates.

[0070] (Formula 1) Q = qs + qm

[0071] Since the measurement error is the flow rate qm flowing through the sub-passage 54, the following equation 2 holds for calculating the error flow rate qm from the above equation 1.

[0072] (Formula 2) qm = Q - qs

[0073] Graph Gr1 in Fig. 9 shows the flow F of the fluid to be measured when the fluid to be measured flows into the upstream opening 55 (17), i.e., the resistance curve of the flow F of the fluid to be measured in the flow path from the upstream opening 55 (17) to 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 sub-flow path 54 (13). Graph Gr2 in Fig. 9 shows the resistance curve of the flow fs of the fluid to be measured in the main flow path 53. Here, the horizontal axis of graphs Gr1 and Gr2 in Fig. 9 represents the flow rate, and the vertical axis represents the pressure difference.

[0074] If the flow rates at the pressure difference ΔP1 are Q1, qs1, and qm1, the error flow rate qm1 at that time is given by the following equation 3 from the above equation 2.

[0075] (Formula 3) qm1 = Q1 - qs1

[0076] Here, if the maximum error in flow rate measurement is set to t%, the relationship of the following equation 4 holds from the above equation 3.

[0077] (Formula 4) qm1 / Q1<t / 100

[0078] Therefore, the flow resistance of the secondary flow path 54 is determined so that its resistance curve satisfies Equation 4 above. The resistance curve of a certain flow path is determined approximately at the point where the cross-sectional area of ​​the flow path is smallest, and therefore depends largely on the cross-sectional area of ​​the throttling sections 59 and 60 of the secondary flow path 54, for example, as shown in FIG. 8 . In other words, it depends largely on the gap dimension s. For example, the flow resistance of the secondary flow path 54 is obtained by simulation while changing the gap dimension s, and the gap dimension s that provides the flow resistance of the secondary flow path 54 that satisfies Equation 4 above is determined. Once the gap dimension s is determined, the cross-sectional areas of the throttling sections 59 and 60 are also determined. The throttling sections 59 and 60 are formed based on the determined cross-sectional areas of the throttling sections 59 and 60. The cross-sectional shapes of the throttling sections 59 and 60 may be rectangular or trapezoidal. Alternatively, the cross-sectional shapes of the throttling sections 59 and 60 may be other shapes.

[0079] That is, the throttle portions 59, 60 (27) are formed based on the flow resistance determined so as to satisfy the above-mentioned formula 4.

[0080] Next, the measurement operation will be described. As shown in Figure 4A, the main flow path 9 with a rectangular cross section is divided by partition plates 15, and each divided flow path has a multilayer section 16 with a large aspect ratio, thereby rectifying the flow and maintaining a stable flow state over a wide flow rate range from low to high. Under these conditions, ultrasonic waves are transmitted and received via the ultrasonic propagation path M by the ultrasonic transmitter / receiver 8a and the ultrasonic transmitter / receiver 8b, as shown in Figure 5.

[0081] Such ultrasonic transmission and reception operations are performed by the control unit 20 shown in Fig. 1, and the flow velocity V can be determined from the data obtained thereby using the known reciprocal propagation time difference method in the signal processing unit 21. The flow rate Q of the fluid to be measured can be determined by multiplying this flow velocity V by the flow path cross-sectional area S and then by a correction flow coefficient k. In other words, the flow rate Q can be determined using the formula "Q = k x V x S." At this time, the previously determined flow rate Q can be converted into a value under standard conditions in the signal processing unit 21 using the pressure obtained from the pressure sensor 4 and the temperature obtained from the temperature sensors 6 and 7.

[0082] That is, the flow rate can be calculated based on the propagation time obtained from the pair of ultrasonic transmitters and receivers 8a and 8b using a conventionally known method, and the flow rate under standard conditions can be obtained by correcting this value for temperature and pressure.

[0083] Here, the error in flow rate measurement at this time will be considered.

[0084] Since the flow rate of the sub-passage 54 is greatest when no water droplets are retained therein, the error when no water droplets are retained is considered to be the maximum error. As described above, the resistance curve of the sub-passage 54 is determined to satisfy the above formula 4, so it is guaranteed that the error will be smaller than the predetermined value t %.

[0085] Furthermore, as an example of concentration measurement, the hydrogen concentration of a fluid to be measured that has humidity can be measured by the following procedure.

[0086] First, the moisture concentration "Dw" in the fluid is determined based on the relative humidity "Tw" obtained from the relative humidity sensor 5, the temperature "Td" obtained from the average value of the temperature sensors 6 and 7, and the pressure "p" obtained from the pressure sensor 4. Next, the concentration of hydrogen including humidity can be determined based on the upstream-to-downstream propagation time "tdw" and downstream-to-upstream propagation time "tup" obtained from the ultrasonic transmitter-receivers 8a and 8b, the temperature "Td" obtained from the temperature sensor, and the previously determined moisture concentration "Dw."

[0087] [1-3. Effects, etc.] As described above, in this embodiment, the physical quantity measuring device has a main flow path 9, an upstream opening 17 provided on the upstream side of the main flow path 9, a downstream opening 18 provided on the downstream side of the main flow path 9, and a sub-flow path 13 provided outside the main flow path 9 and connecting the upstream opening 17 and the downstream opening 18, and the sub-flow path 13 is configured to have a throttle portion 27 in a part thereof.

[0088] This reduces the flow rate difference (resistance difference) caused by the difference in the cross-sectional area of ​​the sub-passage due to the presence or absence of water droplets, even if the fluid to be measured that flows into the physical quantity measuring device 22 contains water droplets. Therefore, it is possible to maintain the accuracy of gas flow rate measurement in a high-humidity environment while also ensuring a path for water droplets.

[0089] Furthermore, as in the present embodiment, the physical quantity measuring device 22 may be configured such that the flow rate measurement sensors 8a, 8b are arranged in the main flow path 9 so as to protrude into the flow, and may include a communication section 26 that connects to the sub-flow path 13 from the vicinity of the notch 19 of the partition plate 15. The throttle section 27 of the sub-flow path 13 may be provided before and after a portion (connection section) where the sub-flow path 13 and the communication section 26 are connected. In other words, the throttle section 27 may be provided between the upstream and downstream of the connection section where the sub-flow path 13 and the communication section 26 are connected.

[0090] As a result, even if fine water droplets flow into the main flow path 9 and collide with the flow rate measurement sensors 8a, 8b, the water droplets will drip from the communicating portion 26 connected to the sub-flow path 13 into the sub-flow path 13, preventing the water droplets from remaining on the flow rate measurement sensors 8a, 8b and preventing the measurement accuracy from being adversely affected by the adhesion of water droplets. Furthermore, by providing a restrictor portion 27 between the upstream and downstream ends of the connecting portion where the sub-flow path 13 and the communicating portion 26 are connected, the flow rate of the sub-flow path 13 can be appropriately suppressed even at the portion connected to the communicating portion 26, thereby ensuring the accuracy of flow rate measurement in the main flow path 9.

[0091] Furthermore, as in this 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 have a multi-layer portion 16 formed by partition plates 15 that divide the main flow path 9 into multiple layers. In this case, the flow rate measuring sensors 8a and 8b are disposed in the multi-layer portion 16.

[0092] This makes it possible to make the flow velocity and flow rate distribution uniform throughout the entire flow path, and therefore, even if the flow rate measurement sensors 8a and 8b do not cover the entire width of the flow path, it is possible to measure the flow rate stably and with high accuracy.

[0093] Furthermore, as in the present embodiment, the physical quantity measuring device 22 may include temperature sensors 6 and 7 for detecting the temperature of the fluid and a pressure sensor 4 for detecting the pressure of the fluid in the main flow path 9. The flow rate measuring sensors 8 a and 8 b, the temperature sensors 6 and 7, and the pressure sensor 4 are electrically connected to the signal processing unit 21.

[0094] As a result, the signal processing unit 21 receives the flow rate signal of the fluid to be measured from the flow rate measurement sensors 8a and 8b, the accurate temperature of the fluid to be measured from the temperature sensors 6 and 7, and the accurate pressure of the fluid to be measured from the pressure sensor 4, and converts and measures the accurate flow rate of the fluid under standard conditions.

[0095] Furthermore, as in this embodiment, the flow rate measuring sensors 8a, 8b may be a pair of ultrasonic transmitters / receivers 8a, 8b, and the physical quantity measuring device 22 may include a humidity sensor 5 that detects the humidity of the fluid. The flow rate measuring 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.

[0096] This allows the flow velocity and flow rate to be determined by a known reciprocal time difference method using the propagation time of ultrasonic waves transmitted and received by the pair of ultrasonic transmitters and receivers 8 a and 8 b. Furthermore, the concentrations of components contained in the fluid, excluding water vapor, can be determined using a known method based on the sound speed obtained using the propagation time of ultrasonic waves transmitted and received by the pair of ultrasonic transmitters and receivers 8 a and 8 b, the measured values ​​of the temperature sensors 6 and 7, and the measured value of the humidity sensor 5.

[0097] In this way, the flow rate of the fluid and the concentration of components contained in the fluid are measured by preventing water droplets from entering the flow rate measuring section (flow rate measuring sensors 8a, 8b).

[0098] As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the first embodiment to create new embodiments.

[0099] Therefore, other embodiments will be exemplified below.

[0100] In the first embodiment, the partition plate 15 of the multilayer unit 16 is installed almost horizontally, but the partition plate 15 may be installed vertically. In this case, some of the water droplets generated by collision can be made to drip down the partition plate.

[0101] In the first embodiment, a pair of temperature sensors 6, 7 are provided on the upstream and downstream sides of the flow path section 1, but in cases where the temperature gradient of the fluid is small, a single temperature sensor may be sufficient, which makes it possible to reduce costs.

[0102] In the first embodiment, the pressure sensor 4 is disposed on the outermost layer side of the multi-layer section 16 in the height H direction, but it may also be disposed in the width W direction relative to the central layers of the multi-layer section 16. In particular, when disposed on the signal processing section 21 side, it is possible to make the configuration more compact and reduce costs by integrating the pressure sensor 4 with the control board section that constitutes the signal processing section 21 and by simplifying the connection wiring.

[0103] In the first embodiment, the physical quantity measuring device 22 is configured to use a pair of ultrasonic transmitter-receivers 8a and 8b as an example of a flow rate measuring unit that measures the flow rate, but is not limited to this configuration. The physical quantity measuring device 22 may also use a thermal sensor as an example of a flow rate measuring unit. In this case, it is not necessary to provide a pair of thermal sensors. Therefore, for example, it is sufficient to simply place a thermal sensor in place of the ultrasonic transmitter-receiver 8a shown in FIG. 1.

[0104] In the first embodiment, the pair of ultrasonic transmitter-receivers 8 a, 8 b and the humidity sensor are used as an example of concentration measurement, but a concentration sensor capable of measuring the concentration of a specific gas may also be used. In this case, it is sufficient to simply place the pair of ultrasonic transmitter-receivers 8 a, 8 b or a thermal sensor as a flow rate measurement sensor and the concentration sensor in place of the humidity sensor 5.

[0105] In this embodiment, the main flow path 9 is divided into multiple layers by the partition plates 15 to form the multi-layer portion 16, but it goes without saying that the main flow path 9 may be a single layer without using the partition plates 15.

[0106] In the first embodiment, the case where water droplets are mixed into the fluid to be measured has been described as an example, but the same effect can be expected not only for water droplets but also for droplets of liquids other than water.

[0107] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0108] (Summary) As described above, the physical quantity measuring device (22) of the first aspect includes a flow path main body (11), a flow rate measuring unit (e.g., ultrasonic transmitter / receivers 8a, 8b), a signal processing unit (21), an upstream opening (17), a downstream opening (18), and a sub-flow path (13). The flow path main body (11) has a main flow path (9). The flow rate measuring unit is provided in the main flow path (9). The signal processing unit (21) receives a signal from the flow rate measuring unit and measures the flow rate of the fluid. The upstream opening (17) is provided upstream of the main flow path (9). The downstream opening (18) is provided downstream of the main flow path (9). The sub-flow path (13) is provided outside the main flow path (9) and connects the upstream opening (17) and the downstream opening (18). The sub-flow path (13) has a constriction portion (27) in the flow path that constricts the flow path cross section.

[0109] According to this aspect, even if the fluid contains condensed water droplets, it is possible to accurately measure the gas flow rate and gas concentration in a high humidity environment while also ensuring a path for the condensed water droplets.

[0110] In the physical quantity measuring device (22) of the second aspect, in the first aspect, the flow rate measuring unit is disposed in the main flow path (9) so as to protrude into the flow. The flow rate measuring unit has a communication unit (26) that connects from the vicinity of the protruding portion of the flow rate measuring unit to the secondary flow path (13). The throttle unit (27) is disposed before and after the part where the secondary flow path (13) and the communication unit (26) are connected.

[0111] According to this aspect, a resistance effect can be imparted to the bypass flow of the fluid to be measured that flows from the sub-flow path (13) to the main flow path (9) via the communicating part (26). Furthermore, a resistance effect can be imparted to the bypass flow of the fluid to be measured that flows from the main flow path (9) to the sub-flow path (13) via the communicating part (26).

[0112] In the physical quantity measuring device (22) of the third aspect, in the first or second aspect, the main flow path (9) has a multilayer portion (16) configured with partition plates (15) that have a rectangular cross section and divide the main flow path (9) into multiple layers. The flow rate measuring unit is disposed in the multilayer portion (16).

[0113] According to this embodiment, the two-dimensionality of the fluid flow in the main flow path (9) is improved, and the flow velocity distribution in the main flow path (9) can be made uniform.

[0114] A fourth aspect of the physical quantity measuring device (22) is the device of any one of the first to third aspects, further comprising a temperature sensor (6, 7) for detecting the temperature of the fluid and a pressure sensor (4) for detecting the pressure of the fluid, in the main flow path (9). The signal processing unit (21) receives signals from the flow rate measuring unit, the temperature sensors (6, 7), and the pressure sensor (4) to measure the flow rate of the fluid.

[0115] According to this aspect, even if the fluid contains condensed water droplets, it is possible to accurately measure the gas flow rate under standard conditions in a high humidity environment.

[0116] The physical quantity measuring device (22) of the fifth aspect is the fourth aspect, further comprising a humidity sensor (5) for detecting the humidity of the fluid in the main flow path (9). The flow rate measuring unit is a pair of ultrasonic transmitters and receivers (8 a, 8 b). The signal processing unit receives signals from the flow rate measuring unit, signals from the temperature sensors (6, 7), signals from the pressure sensor (4), and signals from the humidity sensor (5) to measure the flow rate and component concentrations of the fluid.

[0117] According to this aspect, even if the fluid contains condensed water droplets, it is possible to accurately measure the gas flow rate and the gas concentration in a high humidity environment.

[0118] In a sixth aspect of the physical quantity measuring device (22), in any one of the first to fifth aspects, the throttle 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 determined so that, when a fluid not containing water flows through the flow path from the upstream opening (17) to the downstream opening (18), the difference between a first flow rate (Q) of the fluid flowing through the flow path and a second flow rate (qs) of the fluid flowing through the main flow path (9) at a predetermined pressure difference (ΔP) divided by the first flow rate is smaller than a predetermined value (t).

[0119] According to this aspect, the error in flow rate measurement due to the presence or absence of water droplets can be reduced to a predetermined value or less, thereby enabling gas flow rate measurement and gas concentration measurement to be performed with high accuracy.

[0120] The present disclosure can suppress the difference in the cross-sectional area through which gas passes and the fluctuation in the measured flow rate that occur due to the presence or absence of condensed water droplets even when the inflowing flow contains water droplets, and therefore can be applied to physical quantity measurement devices that must simultaneously measure gas flow rates and gas concentrations stably in high-humidity environments while ensuring a path for water droplets. Specifically, the present disclosure can be applied not only to devices that have both a flow meter and component measurement, but also to devices that only have a flow meter or only component measurement.

[0121] REFERENCE SIGNS LIST 1 Flow path section 2 Fluid inlet 3 Fluid outlet 4 Pressure sensor 5 Relative humidity sensor (humidity sensor) 6 Temperature sensor 7 Temperature sensor 8a Ultrasonic transmitter / receiver (flow rate measurement sensor, flow rate measurement section) 8b Ultrasonic transmitter / receiver (flow rate measurement sensor, flow rate measurement section) 9 Main flow path 10 Internal space 11 Flow path main body 11a Recessed portion side 12 Flow path lid 12a Convex portion 12b Flat plate portion 13 Sub-flow path 14 Groove 15 Partition plate 16 Multilayer portion 17 Upstream opening 18 Downstream opening 19 Notch portion 20 Control section 21 Signal processing section 22 Physical quantity measuring device 23 Mounting portion 24 Spacer 25 Packing 26 Communication portion 27 Constriction portion 51 Model flow path section 52 Inlet space portion 53 Main flow path 54 Sub-flow path 55 Upstream opening 56 Outlet space portion 57 Downstream opening portion 58 Communication portion 59 Throttle portion 60 Throttle portion CH1 Inlet space portion CH2 Outlet space portion

Claims

1. A flow path body having a main flow path; A flow rate measuring unit provided in the main flow path; a signal processing unit that receives a signal from the flow rate measuring unit and measures the flow rate of the fluid; An upstream opening provided on the upstream side of the main flow path; A downstream opening provided on the downstream side of the main flow path; a sub-flow passage provided outside the main flow passage and connecting the upstream opening and the downstream opening, The sub-flow passage has a constriction portion in the flow passage that constricts the flow passage cross section. Physical quantity measuring device.

2. the flow rate measuring unit is disposed in the main flow path so as to protrude into the flow, and has a communication unit that is connected to the sub-flow path from a vicinity of the protruding portion of the flow rate measuring unit, The throttle portion is disposed before and after a portion where the sub-flow passage and the communication portion are connected. The physical quantity measuring device according to claim 1 .

3. The main flow path has a rectangular cross-sectional shape and includes a multi-layer portion formed by partition plates that divide the main flow path into multiple layers, The flow rate measuring unit is disposed in the multi-layer unit. The physical quantity measuring device according to claim 1 .

4. The main flow path is provided with a temperature sensor for detecting a temperature of a fluid and a pressure sensor for detecting a pressure of the fluid, the signal processing unit receives a signal from the flow rate measuring unit, a signal from the temperature sensor, and a signal from the pressure sensor to measure a flow rate of a fluid. The physical quantity measuring device according to claim 1 .

5. A humidity sensor for detecting the humidity of the fluid is further provided in the main flow path, The flow rate measuring unit is a pair of ultrasonic transmitters and receivers, the signal processing unit receives a signal from the flow rate measuring unit, a signal from the temperature sensor, a signal from the pressure sensor, and a signal from the humidity sensor, and measures a flow rate and a component concentration of the fluid. The physical quantity measuring device according to claim 4 .

6. The throttle portion is formed based on the flow resistance of the sub-flow path, the flow resistance of the sub-flow passage is determined such that, when a fluid not containing moisture flows in the flow passage from the upstream opening to the downstream opening, a value obtained by dividing a difference between a first flow rate of the fluid flowing in the flow passage and a second flow rate of the fluid flowing in the main flow passage at a predetermined pressure difference by the first flow rate is smaller than a predetermined value. The physical quantity measuring device according to claim 1 .