JPH09257530A - Fluid vibration detector - Google Patents

Abstract

(57) [PROBLEMS] To provide a fluid vibration detection device that does not cause an output abnormality without dew condensation inside a pressure detector even when a measurement fluid is in a high humidity state. A seal material 62 is provided between a pressure detector 11 and a housing 2 that houses the pressure detector 11 to insulate the pressure detector 11 from the housing 2. Alternatively, a pressure guiding member having a curved pressure transmission path for guiding pressure vibration to the housing 2 is provided to increase the heat capacity of the pressure guiding member as compared with the heat capacity of the housing 2, or the pressure guiding member and the housing. Two
A heat sink may be provided between the pressure transmitting member and the pressure transmitting member, and a water reservoir may be provided in a part of the pressure transmitting member of the pressure guiding member, or a hygroscopic material portion may be provided in the pressure transmitting member.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid vibration detecting device used in a Karman vortex flowmeter or fluidic flowmeter for detecting the frequency of pressure vibration in a fluid and measuring the flow velocity and flow rate of the fluid.

2. Description of the Related Art As a conventional fluid vibration detecting device, there is known a device using an electret film as a pressure detector, as disclosed in Japanese Patent Laid-Open No. 7-991991. 7 and 8 show a conventional fluid vibration detection device described in Japanese Patent Application Laid-Open No. 7-91991. FIG. 7 is a sectional view of a main part of the fluid vibration detecting device, and FIG. 8 is a sectional view of a pressure detector. As shown in FIG. 7, the fluid vibration detecting device is arranged above the vortex generator 5 with a seal member 4 interposed therebetween.
The pressure difference between the left and right generated in 1 is detected to measure the number of vortices generated, and the flow velocity and flow rate are measured. The fluid vibration detector has 2
Pressure detectors 11 and 12, and two pressure detectors 11 and 12, and pressure transmission paths 21 and 22 that accommodate the two pressure detectors 11 and 12 and guide the pressure difference due to the vortex generated in the vortex generator 5 to the two pressure detectors 11 and 12. And a lid 3 and the like. Further, the two pressure detectors 11 and 12 are, as shown in FIG.
The movable electrode 16 having the electret film formed on the diaphragm 17, the fixed electrode 14 facing the movable electrode 16, and the impedance conversion FET (not shown) connected to the fixed electrode 14 are hermetically sealed in the aluminum case. It is structured such that it is housed with a gap g. This gap g is
It is provided to prevent a decrease in insulation between the electret film, which is the movable electrode 16 on the diaphragm 17, and the fixed electrode 14 when water contained in the fluid enters through the pressure transmission paths 21 and 22.

However, in the above fluid vibration detecting device according to the prior art, the gap g is effective for preventing insulation deterioration in the outer peripheral portions of the diaphragm 17 and the fixed electrode 14, but the pressure detector 11 If a high-humidity fluid is introduced into the inside of
There is a problem that dew condensation between 14 cannot be prevented, and an output abnormality of the pressure detectors 11 and 12 occurs. An object of the present invention is to provide a fluid vibration detection device that does not cause an output abnormality without dew condensation inside the pressure detector even when the fluid to be measured is in a high humidity state.

In order to achieve the above object, in the present invention, as a first structure, a heat insulating structure is provided between a pressure detector and a housing for accommodating the pressure detector. With this configuration, even when the ambient temperature at which dew condensation is most likely to occur is high, it is possible to prevent dew condensation inside the pressure detector. Because the housing has a large heat capacity, it cannot follow the increase in the ambient temperature, and the temperature rises later than the ambient temperature. Therefore, dew condensation may occur inside the housing. If the housing and the pressure detector are thermally well coupled, dew condensation will occur inside the pressure detector. However, if the pressure detector is insulated from the housing, the heat capacity of the pressure detector is small, so that the temperature of the fluid can be closely followed and dew condensation can be avoided. Further, as a second configuration, a pressure guiding member, which is different from the housing, for guiding pressure oscillation to the pressure detector is provided, the heat capacity of this pressure guiding member is made larger than the heat capacity of the housing, and the pressure transmission path for transmitting the pressure is It has a curved shape, and a pressure insulating member and a housing are arranged in a heat-insulated state as required. Furthermore, as a third configuration, a moisture absorbent portion or a water storage portion is provided in the pressure transmission path of the pressure guiding member. When the pressure guiding member is arranged between the pressure generating portion and the housing, the pressure guiding member has a larger heat capacity than the housing, and the pressure transmission path for guiding the pressure is curved,
Since the temperature rise of the pressure guiding member is further delayed, the temperature of this portion becomes lower than the temperature of the housing, and dew condensation occurs at this portion, so that the supply of moisture to the housing portion can be prevented. Moreover, since the pressure transmission path is curved, the effect is more reliable. It is self-evident that the dehumidifying effect will be more reliable if a hygroscopic material is placed in the pressure transmission path. Further, by providing a water reservoir in a part of the pressure transmission path, it is possible to prevent the pressure guiding hole from being clogged with dew condensation water, and it is possible to prevent the water droplet from entering the pressure detector through the pressure transmission path.

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in order to prevent dew condensation inside the pressure detector, it is roughly divided into two configurations. One is to provide a heat insulating structure between the pressure detector and a housing that houses the pressure detector, and the other is to introduce a pressure vibration to the pressure detector, which is different from the housing. A member is provided, the heat capacity of the pressure guiding member is made larger than the heat capacity of the housing, the pressure transmission path for transmitting pressure is curved, and if necessary, the pressure guiding member and the housing are arranged in a heat insulating state, It is to adopt more effective means inside the pressure transmission path. Below, it demonstrates concretely using an Example. Note that the same symbols are used for parts that are common to the prior art.

[First Embodiment] FIG. 1 is a cross-sectional view of a main part of a first embodiment of a fluid vibration detecting device according to the present invention, in which a portion of a housing 2 in which a first pressure detector 11 is housed is accommodated. 3 shows a cross section of a main part of FIG. Although not shown in FIG. 1, the second pressure detector 12 is also housed in the housing 2 with the same configuration. The first pressure detector 11 and the second pressure detector 12 are
The structure shown in FIG. 8 of the conventional example, that is, a movable electrode having an electret film formed on a diaphragm, a fixed electrode facing the movable electrode, an impedance conversion FET connected to the fixed electrode, and the like have an aluminum thickness of about 0.3 mm. It is housed in a case, and its outer shape is as small as 10mm cubic and its heat capacity is small. The difference from the conventional example is that the first
Of the pressure detector 11 is held in the housing 2 with a gap so as not to contact the housing 2, and a gas layer 61 is formed between the housing 2 and the first pressure detector 11. That is the point. Reference numerals 21 and 22 denote first and second pressure transmission paths, and one pressure introduced from the vortex generator 5 is from the first pressure transmission path 21 and the other pressure is from the second pressure transmission path.
It is configured to be guided to the first pressure detector 11 from the pressure transmission path 22. The sealing material 62 serves to secure the space between the housing 2 and the first pressure detector 11 and also to secure the space between the first pressure transmission path 21 and the first pressure transmission path 21.
Has the purpose of isolating the pressure in the second pressure transmission path 22 from the pressure in the second pressure transmission path 22. The upper part of the housing 2 is hermetically closed by a lid 3, a clamp ring 27 and an O-ring 25. Seal material
The feature of this embodiment is that the housing 2 and the first pressure detector 11 are provided with a heat insulating structure by including the 62 and the gas layer 61. With such a structure, the fluid from the first and second pressure transmission paths flows into the space around the pressure detector, and even if the fluid has a high humidity, pressure with a small heat capacity is obtained. Condensation around and inside the detector can be prevented.

[Second Embodiment] FIG. 2 is a cross-sectional view of essential parts showing a second embodiment of the fluid vibration detecting apparatus according to the present invention. The same members as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and only different portions will be described. The second embodiment is different from the first embodiment in that the seal material 62 and the gas layer 61 in the first embodiment are replaced with the heat insulating material 63. Therefore, the heat insulating material 63 also has a sealing function. With such a configuration, it is possible to prevent dew condensation inside the pressure detector even when the fluid has high humidity.

[Third Embodiment] FIG. 3 is a cross-sectional view of essential parts showing a third embodiment of the fluid vibration detecting apparatus according to the present invention. In this embodiment, the pressure guiding member 7 is inserted between the housing 2 and the vortex generator 5 of the conventional fluid vibration detecting device. The pressure guiding member 7 is, for example, made by stacking preliminarily perforated plates, has a curved pressure transmission path 71 for transmitting the pressure guided from the vortex generator 5, and is formed by the seal member 4 according to the conventional technique. It is attached to the housing 2 of the fluid vibration detection device. Further, the vortex generator 5 and the pressure guiding member 7 are attached using a mounting packing 72, and the mounting packing 72 should be such that the pressure guiding member 7 contacts the vortex generating body 5 in a wide area. I am using. Although not clear in the figure, the heat capacity of the pressure guiding member 7 is larger than the heat capacity of the housing 2 attached to the upper portion thereof. According to such a configuration, since the pressure guiding member 7 has a large heat capacity, dew condensation may occur in the pressure transmission path 71, but the pressure guiding member 7 is insulated from the pressure guiding member 7 and is housed in the housing 2 having a small heat capacity. Condensation does not occur with the pressure detector.

[Fourth Embodiment] FIG. 4 is a sectional view showing the principal parts of a fourth embodiment of the fluid vibration detecting apparatus according to the present invention. In this embodiment, the pressure transmission path 71 of the pressure guiding member 7 in the third embodiment is used.
A hygroscopic material portion 73 is provided inside. This hygroscopic material part
When the high-temperature and high-humidity fluid flows in, 73 absorbs moisture in the fluid and prevents the high-humidity fluid from being guided to the pressure detector. Further, when the condensed water flows into the pressure transmission path 71, it absorbs the water and prevents the water from flowing into the pressure detector and blocking the pressure transmission path.

[Fifth Embodiment] FIG. 5 is a sectional view of the essential parts showing a fifth embodiment of the fluid vibration detector according to the present invention. In this embodiment, the pressure transmission path 71 of the pressure guiding member 7 in the third embodiment is used.
The water reservoir 74 is provided in a part of the. This puddle
When the high-temperature and high-humidity fluid flows, 74 prevents water that has condensed on the inner wall of the pressure transmission passage from flowing into the pressure detector and also blocks the pressure transmission passage. Since the water sump 74 is for preventing the pressure transmission passage 71 from being blocked by dew condensation water, the pressure transmission passage 71
It is installed at a low position.

[Sixth Embodiment] FIG. 6 is a cross-sectional view of essential parts showing a sixth embodiment of the fluid vibration detecting apparatus according to the present invention. In this embodiment, the pressure guiding member 7 is attached to the second embodiment, and moreover,
The heat insulating packing 41 is used for the attachment, and the effect of the pressure guiding member 7 is further enhanced by thermally insulating the housing 2 and the pressure guiding member 7. In addition to the above embodiments, various combinations are possible. That is, it is a combination of the type / presence / absence of the heat insulating structure in the housing 2, the type / presence / absence of the pressure guiding member 7, the type of the bonding material of the housing 2 and the pressure guiding member 7, and the like. In the above embodiments, the pressure detector has been described as the variable capacitance type pressure detector in which the electret film is formed on the diaphragm. It is also effective when using a pressure detector that causes an abnormality when attached.

In the fluid vibration detecting device according to the present invention, the heat capacity of the pressure detector of the fluid vibration detecting device is minimized, so that the response of the pressure detector to the temperature change is maximized and the lower part of the housing is used. Disposing a pressure guiding member having a large heat capacity and a curved pressure transmission path, and further providing a heat insulating structure with the housing and the pressure guiding member,
By providing a dehumidifying material and a water reservoir in the curved pressure transmission path of the pressure guiding member, the effect is further enhanced, and even when the fluid to be measured is in a high humidity state, it can be used in parts other than the pressure detector. Condensation is used to prevent condensation inside the pressure sensor.
By dehumidifying or dew condensation on the housing and pressure guiding member in this way, it is possible to prevent dew condensation inside the pressure sensor, and to prevent water that has condensed outside the pressure sensor from entering the sensor. Since it is prevented, the output abnormality of the pressure detector does not occur, and a highly reliable fluid vibration detection device can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a fluid vibration detecting device according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the fluid vibration detecting device according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the fluid vibration detecting device according to the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the fluid vibration detecting device according to the present invention.

FIG. 5 is a sectional view showing a fifth embodiment of the fluid vibration detecting device according to the present invention.

FIG. 6 is a sectional view showing a sixth embodiment of the fluid vibration detecting device according to the present invention.

FIG. 7 is a cross-sectional view showing a fluid vibration detection device according to a conventional technique.

FIG. 8 is a cross-sectional view showing a pressure detector used in a fluid vibration detection device.

[Explanation of symbols]

 11, 12 Pressure detector 13, 15, 18 Insulation ring 14 Fixed electrode 16 Movable electrode 17 Diaphragm 2 Housing 21, 22 Pressure transmission path 23, 24 Dust filter 25, 26 O-ring 27, 28 Clamp ring 3 Lid 4 Seal member 41 Insulation packing 5 Vortex generator 51, 52 Pressure transmission path of vortex generator 61 Gas layer 62 Sealing material 63 Insulation material 7 Pressure guiding member 71 Pressure transmission path 72 Mounting packing 73 Hygroscopic material part 74 Water reservoir

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 000005234 Fuji Electric Co., Ltd. 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Hideo Kato, 959-2 Kawaharayo, Kurihashi-cho, Kitakatsushika-gun, Saitama Prefecture 108 Block 6-2 (72) Inventor Shigenori Okamura 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Within Osaka Gas Co., Ltd. (72) Inventor Shuichi Okada 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. 2 in Osaka Gas Co., Ltd. (72) Inventor Yukio Kimura 507-2 Shintakaracho, Tokai City, Aichi Prefecture Toho Gas Co., Ltd. Research Institute of Technology (72) Inventor Masahiko Matsushita 5-1-11 Hiroo, Shibuya-ku, Tokyo (72) Inventor Noriyuki Hirayama 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Inventor Kikuo Kawasaki 1, Tanabe-shinden, Kawasaki-ku, Kawasaki-shi, Kanagawa Issue Fuji Electric Co., Ltd. in the (72) inventor Tsuruoka Toru彦 Kawasaki City, Kanagawa Prefecture Kawasaki-ku, Tanabeshinden No. 1 No. 1 Fuji Electric Co., Ltd. in

Claims (10)

[Claims] 1. A fluid vibration detecting device comprising a pressure detector and a housing accommodating the pressure detector, wherein a heat insulating means is provided between the pressure detector and the housing accommodating the pressure detector. Fluid vibration detector. 2. The fluid vibration detecting device according to claim 1, wherein the heat insulating means is a fluid layer to be measured or a heat insulating material. 3. A fluid vibration detecting device comprising a pressure detector and a housing accommodating the pressure detector, wherein the fluid vibration detecting device has a curved pressure transmission path for guiding the measured pressure to the pressure detector, and the heat capacity of the pressure detector. A fluid vibration detecting device, wherein a pressure guiding member, which is larger than a heat capacity of a housing for housing the pressure detector, is attached to a housing for housing the pressure detector. 4. The fluid vibration detecting device according to claim 3, wherein a heat insulating means is provided between the pressure guiding member and the housing accommodating the pressure detector. 5. The fluid vibration detecting device according to claim 3 or 4, wherein a water reservoir is provided in a pressure transmission path provided in the pressure guiding member. 6. The fluid vibration detecting device according to claim 3 or 4, wherein a hygroscopic material portion is provided in a pressure transmission path provided in the pressure guiding member. 7. The fluid vibration detecting device according to claim 3, further comprising a heat insulating means between the pressure detector and a housing accommodating the pressure detector. apparatus. 8. The fluid vibration detecting device according to claim 7, wherein the heat insulating means is a fluid layer to be measured or a heat insulating material. 9. The fluid vibration detecting device according to claim 1, wherein the pressure detector is a variable capacitance type detector including a diaphragm having an electret film formed on its surface and a fixed electrode. Fluid vibration detector. 10. The fluid vibration detecting device according to claim 1, wherein the pressure detector is a piezoelectric effect type pressure detector having a diaphragm made of a piezoelectric film.