Physical quantity measuring device

Abstract

To provide a physical quantity measuring device with which, by suppressing water droplets from sticking to an ultrasonic transceiver, it is possible to measure the flow rate or concentration of the fluid of a gas that contains droplets.SOLUTION: Ultrasonic transceivers 4, 5 are arranged by being accommodated inside of opening holes 6, 7 provided in a measurement passage 1, and outer circumferences 4a, 5a of the ultrasonic transceivers 4, 5 are provided, between the inner circumferential walls 6a, 7a of the opening holes 6, 7, with a space part 13 having a prescribed distance T, the distance T of the space part 13 being adjusted to a length suitable for preventing the occurrence of droplet linkage due to liquid drops such as water droplets entering between the outer circumferences 4a, 5a of the ultrasonic transceivers 4, 5 and the inner circumferential walls 6a, 7a of the opening holes 6, 7. Thus, indirect contact between the ultrasonic transceivers 4, 5 and the opening holes 6, 7 is blocked, and the propagation of ultrasonic waves to a housing that causes leakage of vibration from the ultrasonic transceivers 4, 5 to a passage housing 11 is prevented, for a fluid that contains liquid drops too, making it possible to secure measurement reliability and maintain measurement accuracy.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a physical quantity measuring device for measuring characteristics such as the flow rate of a fluid and the concentration of components contained in the fluid by propagating ultrasonic waves through the fluid flowing in a measurement flow path. [Background Art]

[0002] Conventionally, as this type of physical quantity measuring device, there has been known one in which a pair of ultrasonic transducers attached at a certain angle to a measurement flow path through which a fluid to be measured flows is housed and installed in an opening hole opening to the measurement flow path (see, for example, Patent Document 1).

[0003] FIG. 5 shows a cross-section of a measurement flow path of an ultrasonic flowmeter described in Patent Document 1, and FIG. 6 is an enlarged view showing the vicinity of an ultrasonic transducer of the ultrasonic flowmeter described in Patent Document 1.

[0004] In this ultrasonic flowmeter, a pair of ultrasonic transducers 104 and 105 are arranged opposite to each other at a predetermined angle with respect to the flow direction of the fluid to be measured in an opening hole 103 having an opening window 102 opening to the measurement flow path 101. In FIG. 5, the gap between the ultrasonic transducer 105 and the opening hole 103 is set to the minimum necessary dimension such that the ultrasonic transducer 105 does not come into direct contact with the opening hole 103. Further, the opening window 102 is provided with an inflow suppressor 106 which is an ultrasonic wave penetrating body having a large number of fine openings through which ultrasonic waves can pass.

[0005] The inflow of the fluid to be measured flowing through the measurement flow path 101 into the opening hole 103 housing the ultrasonic transducers 104 and 105 is suppressed by the inflow suppressor 106.

[0006] As a measuring device utilizing the propagation of ultrasonic waves, there is a need for a physical quantity measuring device that measures the flow rate, concentration, etc. of a fluid to be measured in which water droplets may be generated, such as exhaust gas from a fuel cell. [Prior Art Documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 3518538 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in the conventional configuration described above, when the fluid to be measured contains water droplets, the water droplets adhere to the inflow suppressor 106 which has many fine openings, and the water droplets that pass through the inflow suppressor 106 and enter the opening hole 103 get trapped in the space 107 between the wall surface of the opening hole 103 and the side surface of the ultrasonic transducer positioned nearby, preventing the water droplets from escaping. This negatively affects the vibration of the ultrasonic transducer, and the ultrasonic vibrations are transmitted to the housing 108 which forms the measurement channel, causing housing propagation to occur, which propagates to the other ultrasonic transducer via the housing 108, degrading the measurement accuracy of the ultrasonic propagation time and negatively impacting the reliability of the measurement.

[0009] The present invention aims to solve the aforementioned conventional problems and to provide a measuring device that can ensure the reliability of measurements without causing deterioration in measurement accuracy when measuring physical quantities such as flow rate and concentration of a gas (fluid to be measured) containing liquid droplets such as water droplets using ultrasound. [Means for solving the problem]

[0010] To solve the aforementioned conventional problems, the physical quantity measuring device of the present invention comprises a measuring channel through which the fluid to be measured flows, a pair of ultrasonic transducers arranged in the measuring channel, and a signal processing unit that receives signals from the pair of ultrasonic transducers to measure the flow rate and component concentration of the fluid, wherein the ultrasonic transducers are housed in an opening in the measuring channel, the outer circumference of the ultrasonic transducers has a space between it and the inner wall of the opening at a predetermined distance, and the distance of the space is such that water enters between the outer circumference of the ultrasonic transducers and the inner wall of the opening. The length of the opening is such that droplet coupling occurs due to droplets such as water droplets, and the opening is provided so as to protrude outward from the measurement channel, and the measurement channel is positioned so that the downstream side is downward in the direction of gravity, and a discharge channel is provided that connects the opening and the downstream outlet side of the measurement channel by passing through a part of the inner circumferential surface of the opening where the downstream ultrasonic transducer is located and the downstream outlet side of the measurement channel, and when viewed from a direction perpendicular to both the direction in which the fluid to be measured flows and the direction in which the pair of ultrasonic transducers are aligned, the discharge channel is and the measurement channel The measurement channel is not overlapping, and an ejector section is provided on the downstream outlet side to draw fluid from the discharge channel. This protects the ultrasonic transducer from indirect contact with the housing by droplets such as water droplets in fluids containing such droplets, ensuring the normal propagation of ultrasound and guaranteeing measurement reliability without degradation of measurement accuracy.

[0011] Furthermore, by positioning the measurement channel so that the downstream side is downward in the direction of gravity, and by providing a discharge channel connecting the opening where the downstream ultrasonic transducer is located to the downstream outlet side of the measurement channel, the increase in liquid droplets such as water droplets around the ultrasonic transducer is suppressed, preventing the propagation of ultrasound to the housing, thereby further improving reliability and maintaining measurement accuracy, and enabling continuous use for long periods of time.

[0012] Furthermore, by providing an ejector section on the downstream outlet side of the measurement channel to draw fluid from the discharge channel, the removal of water droplets and other liquid droplets around the ultrasonic transducer can be promoted, further improving practicality. [Effects of the Invention]

[0013] The physical quantity measuring device of the present invention provides a space on the outer circumference of the ultrasonic transducer with a predetermined distance between it and the inner wall of the opening. The distance of this space is set to prevent droplet fusion caused by water droplets or other liquid droplets entering between the outer circumference of the ultrasonic transducer and the inner wall of the opening. This protects the ultrasonic transducer from indirect contact with the housing by water droplets or other liquid droplets, ensuring normal propagation of ultrasound and thus ensuring measurement reliability without degradation of measurement accuracy. [Brief explanation of the drawing]

[0014] [Figure 1] Cross-sectional view of the physical quantity measuring device in Embodiment 1 of the present invention. [Figure 2] Enlarged view of the vicinity of the downstream ultrasonic transducer in Embodiment 1 of the present invention (Figure 1) [Figure 3] Cross-sectional view of the physical quantity measuring device in Embodiment 2 of the present invention. [Figure 4] Cross-sectional view of the physical quantity measuring device in Embodiment 3 of the present invention. [Figure 5] Cross-sectional view showing the configuration of a conventional ultrasonic flowmeter. [Figure 6] Cross-sectional view showing the configuration near the opening of a conventional ultrasonic flow meter. [Modes for carrying out the invention]

[0015] The first invention comprises a measurement channel through which a fluid to be measured flows, a pair of ultrasonic transducers arranged in the measurement channel, and a signal processing unit that receives signals from the pair of ultrasonic transducers to measure the fluid flow rate and component concentration. The ultrasonic transducers are housed in an opening in the measurement channel, and the outer circumference of the ultrasonic transducers is provided with a space at a predetermined distance from the inner wall of the opening. The distance of the space is set to prevent droplet coupling caused by water droplets or other liquid droplets entering between the outer circumference of the ultrasonic transducers and the inner wall of the opening. This prevents indirect contact between the ultrasonic transducers and the opening, and prevents vibrations from leaking from the ultrasonic transducers to the housing of the measurement channel, even for fluids containing liquid droplets, thereby ensuring measurement reliability and maintaining measurement accuracy.

[0016] In the second invention, the measurement flow path is arranged such that the downstream side is located lower in the direction of gravity, and a discharge flow path is provided to connect the opening hole in which the downstream ultrasonic transducer is arranged to the downstream outlet side of the measurement flow path. This suppresses the accumulation of liquid droplets such as water droplets around the ultrasonic transducer and prevents the propagation of ultrasonic waves to the housing, thereby further improving reliability and ensuring measurement accuracy, and withstanding prolonged continuous use the device can be realized.

[0017] In the third invention, an ejector portion for attracting fluid from the discharge flow path is provided on the downstream outlet side of the measurement flow path, which promotes the removal of liquid droplets such as water droplets around the ultrasonic transducer, prevents propagation of ultrasonic waves to the housing, improves measurement reliability and measurement accuracy, and can further improve practicality for cases containing a large amount of liquid droplets or prolonged continuous use.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, excessive detailed description may be omitted in some cases. For example, detailed description of already well-known matters or repeated description of substantially the same configuration may be omitted.

[0019] The accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0020] (Embodiment 1) Embodiment 1 will be described with reference to FIGS. 1 to 2.

[0021] FIG. 1 is a structural cross-sectional view of the physical quantity measurement device according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged view of the vicinity of the downstream ultrasonic transducer in FIG. 1 according to Embodiment 1 of the present invention.

[0022] In Figures 1 and 2, the measurement channel 1 through which the fluid to be measured flows is equipped with an upstream inlet 2 and a downstream outlet 3. A pair of ultrasonic transducers 4 and 5 are placed in this measurement channel 1, and each ultrasonic transducer 4 and 5 is housed in openings 6 and 7 provided in the measurement channel 1. The ultrasonic transducers 4 and 5 are electrically connected to a signal processing unit 8, which receives signals from the ultrasonic transducers 4 and 5 to measure the fluid flow rate and component concentration.

[0023] As shown in Figure 2, which shows a magnified view of the vicinity of the downstream ultrasonic transducer 5, a matching layer 9 is placed on the ultrasonic wavefront of the ultrasonic transducer 5 to match the impedance with the fluid.

[0024] The ultrasonic transducer 5, equipped with this matching layer 9, is mounted on the sensor support section 10, which positions the ultrasonic transducer 5. Furthermore, the sensor support section 10 not only positions and holds the ultrasonic transducer 5, but also provides vibration isolation support to prevent the ultrasonic vibrations of the ultrasonic transducer 5 from being transmitted to the flow path housing 11, and has an airtight seal section 12 that airtightly seals the outside of the measurement flow path 1.

[0025] A space 13 with a predetermined distance T is provided between the outer circumference 5a of the ultrasonic transducer 5 housed within the opening 7 and the inner circumferential wall 7a of the opening 7. The length of this predetermined distance T in the space 13 is set to prevent droplet fusion caused by water droplets or other liquid droplets entering between the outer circumference 5a of the ultrasonic transducer 5 and the inner circumferential wall 7a of the opening 7.

[0026] Although the description here focuses on the opening 7 housing the downstream ultrasonic transducer 5, the opening 6 housing the upstream ultrasonic transducer 4 has the same configuration and structure, and therefore its description is omitted.

[0027] Next, the operation of the physical quantity measuring device of the present invention will be described.

[0028] The fluid to be measured flows through the measurement channel 1 from the upstream inlet 2 as shown by the white arrow in Figure 1, passes through the ultrasonic propagation path where ultrasonic transducers 4 and 5 are positioned opposite each other, and reaches the downstream outlet of the measurement channel 1. It leaks from 3.

[0029] This device uses a pair of ultrasonic transducers 4 and 5 to measure the fluid velocity and flow rate, as well as the speed of sound, to measure the concentration of components contained in the fluid. These measurements are performed using known methods.

[0030] At this time, fine water droplets that flow into the openings 6 and 7 adhere to the outer circumferences 4a and 5a of the ultrasonic transducers 4 and 5, and attempt to adhere to the inner walls 6a and 7a of the openings 6 and 7. However, a space 13 with a predetermined distance T is provided between the outer circumferences 4a and 5a of the ultrasonic transducers 4 and 5 and the inner walls 6a and 7a of the openings 6 and 7. The length of this space is set to prevent droplet bonding between the outer circumferences 4a and 5a of the ultrasonic transducers 4 and 5 and the inner walls 6a and 7a of the openings 6 and 7. Therefore, propagation of ultrasonic waves to the flow path housing 11 does not occur due to the bonding of water droplets that have entered. Consequently, water droplets do not interfere with the transmission and reception of ultrasonic waves, and stable ultrasonic measurements can be performed.

[0031] The same applies to the opening 6 that houses the upstream ultrasonic transducer 4, so I will omit the explanation.

[0032] Thus, according to this embodiment, the propagation of ultrasonic waves from the ultrasonic transducers 4 and 5 to the flow path housing 11 can be prevented, ensuring the reliability of the measurement and maintaining the accuracy of the measurement.

[0033] Here, we have shown the case with fine water droplets contained in the fluid being measured, but it goes without saying that the same applies to other liquid droplets as well.

[0034] (Embodiment 2) Embodiment 2 will be described with reference to Figure 3. Figure 3 is a cross-sectional view of the physical quantity measuring device in Embodiment 2 of the present invention. Components with the same function as those in Embodiment 1 are given the same reference numerals and their descriptions are omitted.

[0035] In Figure 3, the measurement channel 1 is positioned so that its downstream side is downward in the direction of gravity, and a discharge channel 14 is provided that connects the opening 7 where the downstream ultrasonic transducer 5 is located to the downstream outlet 3, which is the downstream outlet side of the measurement channel 1.

[0036] In this case, even if the fluid to be measured, which contains fine water droplets or other liquid droplets, flows continuously for a long period of time, or if the fluid to be measured contains a large amount of liquid droplets, the accumulated liquid droplets will be drawn down by gravity and flow towards the bottom of Figure 3, passing through the discharge channel 14 and flowing out to the downstream outlet 3 of the measurement channel 1.

[0037] Therefore, even when the fluid to be measured, which contains fine water droplets or other liquid droplets, flows continuously for a long period of time, or when the fluid to be measured contains a large amount of liquid droplets, indirect contact between the outer periphery 5a and the inner periphery wall 7a can be prevented in the downstream ultrasonic transducer 5, thereby preventing the propagation of ultrasonic waves from the ultrasonic transducer 5 to the flow path housing 11, and not hindering the transmission and reception of ultrasonic waves.

[0038] As described above, according to this embodiment, even when the fluid to be measured, which contains fine water droplets or other liquid droplets, flows continuously for a long period of time, or when the amount of liquid droplets contained in the fluid to be measured is large, it is possible to suppress the increase of water droplets or other liquid droplets around the ultrasonic transducers 4 and 5, thereby preventing the propagation of ultrasonic waves to the housing by the liquid droplets, ensuring even greater reliability, and realizing a device that can withstand continuous use for even longer periods of time.

[0039] (Embodiment 3) Embodiment 3 will be described with reference to Figure 4. Figure 4 is a cross-sectional view of the physical quantity measuring device in Embodiment 3 of the present invention. Components with the same functions as those in Embodiments 1 and 2 are given the same reference numbers and their descriptions are omitted.

[0040] In Figure 4, the measurement channel 1 is positioned so that its downstream side is downward in the direction of gravity, and this measurement channel 1 is equipped with an ejector section 15 on the downstream outlet 3 side to draw fluid from the discharge channel 14.

[0041] The ejector section 15 increases the flow velocity by setting the cross-sectional area of ​​the flow path on the outlet side of the measurement flow path 1 to be slightly smaller, thereby generating negative pressure on the outside of the ejector section 15 due to the flow flowing out of the measurement flow path 1, and attracting fluid from the discharge flow path 14.

[0042] At this time, the negative pressure effect generated in the ejector section 15 attracts the liquid that enters the discharge channel 14, causing it to quickly pass through the discharge channel 14 and flow out to the downstream outlet 3 of the measurement channel 1.

[0043] Therefore, this promotes the removal of water droplets and other liquid droplets around the downstream ultrasonic transducer 5, where droplets are likely to form.

[0044] Thus, according to this embodiment, the removal of liquid droplets such as water droplets around the ultrasonic transducer can be promoted, preventing the propagation of ultrasonic waves to the housing, ensuring the reliability of measurements and maintaining measurement accuracy, and further improving practicality for situations involving many liquid droplets or for long-term continuous use.

[0045] As described above, in Embodiments 1 to 3 of the present invention, the cross-sectional shape of the measurement channel 1 may be rectangular or circular, and it goes without saying that it is effective regardless of the cross-sectional shape. [Industrial applicability]

[0046] As described above, the physical quantity measuring device of the present invention can eliminate the adverse effects of water droplets on the ultrasonic transducer even when dealing with fluids containing water droplets. This ensures reliable measurement and maintains measurement accuracy without the influence of water droplets, thus realizing a highly practical physical quantity measuring device. [Explanation of Symbols]

[0047] 1. Measurement channel 2 Upstream entrance 3 downstream exit 4, 5 Ultrasonic transducers 4a, 5a outer circumference 6, 7 Opening holes 6a, 7a Inner wall 8. Signal Processing Unit 9 Matching layer 10 Sensor support section 11 Flow channel housing 12 Airtight seal section 13 Space section 14 Discharge channel 15 Ejector section

Claims

[Claim 1] The measurement channel through which the fluid to be measured flows, A pair of ultrasonic transducers arranged in the aforementioned measurement channel, The system includes a signal processing unit that receives signals from a pair of ultrasonic transducers and determines the fluid flow rate and component concentration, The ultrasonic transducer is housed and positioned within an opening in the measurement channel, and the outer circumference of the ultrasonic transducer has a space between it and the inner wall of the opening at a predetermined distance, and the distance of the space is such that droplet fusion occurs due to droplets such as water droplets entering between the outer circumference of the ultrasonic transducer and the inner wall of the opening. The aforementioned opening is provided so as to protrude outward from the measurement channel, The measurement channel is positioned so that its downstream side is downward in the direction of gravity, and a discharge channel is provided that connects the downstream outlet side of the measurement channel by passing through a part of the inner circumferential surface of the opening where the downstream ultrasonic transducer is located and the downstream outlet side of the measurement channel. When viewed from a direction perpendicular to both the direction in which the fluid to be measured flows and the direction in which the pair of ultrasonic transducers are aligned, the discharge channel does not overlap with the measurement channel. The measurement channel is a physical quantity measuring device equipped with an ejector section on the downstream outlet side to draw fluid from the discharge channel.

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