JP2003254847A - Differential pressure detector, level gauge and flowmeter fitted therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential pressure detector which can approximately equalize a first-pressure side sealing liquid and a second-pressure side sealing liquid in quantity without making each member of a detecting element larger, and enables its size reduction. <P>SOLUTION: A sealing liquid 17 for high pressure and a sealing liquid 18 for low pressure which are put in and sealed by a first sealing diaphragm 19 and a second sealing diaphragm 20, are put on two side surfaces of a body 12, and a flange 13 for high pressure and a flange 14 for low pressure are placed at positions respectively opposite to the sealing diaphragms 19, 20, and a differential pressure detector 1 fitted with a detecting element 40 for detecting the pressure difference between the sealing liquids 17, 18 is formed. Each of the sealing liquids 17, 18 is poured up to the detecting element 40 through a pipe 45 for high pressure or a pipe 46 for low pressure respectively. Inside diameters of individual pipes 45, 46 are set to different values so that the volumes of the sealing liquids for high pressure and low pressure become approximately equal to each other. Accordingly, the quantities of the high-pressure side and the low-pressure side sealing liquids which are put in can be made approximately equal, and the size of the differential pressure detector can be reduced, since it is not necessary to make each member of the detecting element larger. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure detector for detecting a pressure difference between two places having different pressures, a flow meter and a liquid level gauge equipped with the differential pressure detector.

[0002]

BACKGROUND ART A differential pressure detector that detects a pressure difference between two locations having different pressures is known. This differential pressure detector is, for example,
It is used to measure the flow rate of fluids such as water and gas, and to measure the liquid level in tanks. FIG. 9 shows a conventional example of a sealed differential pressure detector 90 that detects the pressure of the sealed liquid sealed inside. The enclosed differential pressure detector 90 is configured to have a pressure receiving portion 110 that receives the pressure of the fluid to be measured from two different pressure locations, and a differential pressure detecting portion 120 that detects the pressure difference between the pressure receiving portions 110. ing. The pressure receiving portion 110 includes a main body 92 fixed to a mounting member 91, and first and second seal diaphragms 97 and 98 for sealing the pressure of the fluid to be measured are attached to both side surfaces of the main body 92. . In addition, the seal diaphragms 9 are provided on both side surfaces of the main body 92.
The first and second filled liquids 99 and 100, which are filled in the concave portions facing the surfaces 7 and 98 and to which the pressure is transmitted from the seal diaphragms 97 and 98, are filled.

A first pressure introducing member (high pressure flange) 93 for introducing a high pressure, for example, is provided outside the first seal diaphragm 97 of the main body 92, and a low pressure is provided outside the second seal diaphragm 98. The second pressure introducing member (low-pressure flange) 94 for introducing the pressure is provided. Further, the pressure receiving section 110 and the differential pressure detecting section 120 are
Fill liquids 99 and 100 are filled through high-pressure pipe 95 and low-pressure pipe 96, respectively. The differential pressure detection unit 120 includes a terminal pedestal 121, and the terminal pedestal 121
A sensor 123 is provided via a sensor base 122, and the terminal support 121 is covered with a cap 124. In the space 133 formed by the cap 124, the terminal support 121, and the sensor base 122, the high-pressure side filled liquid 9
9 is filled, while the low-pressure side filled liquid 100 is filled.
Is filled from the pipe 96 to the space 133A of the sensor base 122.

[0004]

By the way, in the sealed type differential pressure detector, if the amount of the sealed liquid in the pressure receiving portion 110 on the high pressure side, which is the first pressure, and the low pressure side, which is the second pressure, is not the same, It is difficult to accurately measure the pressure difference between the two due to the influence of expansion of the enclosed liquid due to temperature change. In the conventional sealed differential pressure detector, the height of the sensor base 122 is increased and the space 133A in the sensor base 122 is increased in order to make the amount of the filled liquid on the high pressure side and that on the low pressure side the same. , Trying to balance the high pressure side and the low pressure side filled liquids 99 and 100. However, on the high-pressure side, there is the filled liquid only in the high-pressure pipe 95 except for the same length as the low-pressure pipe 96, that is, the inverted J-shaped pipe portion and the space 133, but on the low-pressure side, the sensor is Pipe 9 on the base 122
The enclosed liquid is present only for the space 133A having a predetermined height dimension formed by the diameter of 6. In such a state, in order to make the high-pressure side and the low-pressure side filled liquid amounts substantially equal, the sensor base 1
The height of 22 must be made considerably high, and if so, the height of the entire detection unit 120 is also increased, which causes a problem that the differential pressure detector cannot be downsized.

An object of the present invention is to make the amounts of the enclosed liquids on the first pressure side and the second pressure side substantially the same without increasing the size of each member of the detection section, and to reduce the size. It is to provide a pressure detector.

Another object of the present invention is to provide a flow meter and a liquid level gauge equipped with a differential pressure detector in which the amounts of filled liquid on the first pressure side and the second pressure side are substantially the same. is there.

[0007]

According to a first aspect of the present invention, there is provided a main body having a predetermined thickness, and first and second peripheral side portions of the main body which are airtightly fixed at predetermined intervals on two side surfaces of the main body. A gap formed between the second seal diaphragm and the main body and the first and second seal diaphragms is filled, and the first and second pressures are transmitted through the respective seal diaphragms. First and second filled liquids,
A first pressure introducing member provided opposite to the first seal diaphragm and introducing the first pressure into the first seal diaphragm; and a second pressure introduction member provided opposite to the second seal diaphragm. A differential pressure detector comprising: a second pressure introducing member for introducing a pressure; and a detector for detecting a pressure difference between the first and second filled liquids, the first and second filled liquids. Are filled up to the detection portion via the first and second pipes, respectively, and the volumes of the first and second filled liquids are substantially the same on the first pressure side and the second pressure side. Therefore, the inner diameters of the first and second pipes are set to different sizes.

According to the present invention as described above, only by setting the inner diameters of the first pipe and the second pipe to different sizes, the amount of the enclosed liquid on the first pressure side and the amount of the enclosed liquid on the second pressure side can be set. Can be approximately the same. Further, since it is not necessary to increase the size of each member of the detection unit, the differential pressure detector can be downsized.

In the above invention, the fluid to be measured is
It includes liquids such as water and solutions, and gases such as gas and air. Further, it is preferable to use, for example, silicone oil, which is a non-compressible fluid, as the filling liquid, but any other fluid may be used as long as it can obtain the same effect as silicone oil.

According to a second aspect of the present invention, in the differential pressure detector according to the first aspect, the internal volume of each of the first and second pipes on the first enclosed liquid side and the second enclosed liquid side is determined. Vd is the difference in volume of the removed portion, Lp is the pipe length assuming that the first and second pipe lengths are substantially equal, the cross-sectional area of the first pipe is Ah, and the cross-sectional area of the second pipe is Al. When
The inner diameters of the first and second pipes are set so as to have a relationship represented by the formula: Al-Ah = Vd / Lp. According to the present invention as described above, it is possible to easily determine the sizes of the high pressure pipe and the low pressure pipe that vary depending on the type of the differential pressure detector.

The invention according to claim 3 is a flow meter characterized by comprising the differential pressure detector according to claim 1 or 2. According to the present invention as described above, it is possible to detect the pressure at two positions having different pressures with the differential pressure detector and measure the flow rate based on the detected value.
It becomes easy to measure the flow rate of water, solution pipes, and gas pipes.

A fourth aspect of the invention is a liquid level gauge comprising the differential pressure detector according to the first or second aspect. According to the present invention as described above, it is possible to detect the pressure at two positions having different pressures by the differential pressure detector and measure the liquid level based on the detected value, so that the sealed tank in various processes and the like can be obtained. It becomes easy to measure the liquid level of.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a differential pressure detector 1 according to the first embodiment. The differential pressure detector 1 includes a pressure receiving portion 10 that receives the pressure of the fluid to be measured at two different locations, and a differential pressure detecting portion 40 that detects the pressure difference between the pressure receiving portions 10. .

The pressure receiving portion 10 is, for example, a plate-shaped mounting member 11
A main body 12 fixed to the main body 12, a high pressure flange 13 which is a first pressure introducing member provided on one side of both side surfaces of the main body 12, and an outer side of the other side of the main body 12. And a low pressure flange 14 that is a second pressure introducing member provided. Mounting member 1
The main body 12, the high-pressure flange 13 and the low-pressure flange 14 are arranged on the facing surface (rear surface) 11A side of 1, and the differential pressure detecting section 40 is arranged on the front surface side of the mounting member 11.

The main body 12 is formed of, for example, a cylindrical member having a predetermined thickness. A concave portion 15 is formed on a side surface of the main body 12 on the side of the high pressure flange 13 to form a gap having a predetermined depth, and the concave portion 15 has a high pressure which is a first filled liquid which will be referred to later. The filling liquid 17 is full. In addition, the low pressure flange 14 in the main body 12
The side surface on the side is formed with a concave portion 16 forming a gap having a predetermined depth dimension, and the concave portion 16 is filled with a low-pressure filling liquid 18 which is a second filling liquid to be referred to later. . Silicon oil, which is a non-compressible fluid, is used as the filled liquids 17 and 18, for example.

A high-pressure seal diaphragm 19 as a first seal diaphragm is arranged on the outer peripheral edge of the recess 15 of the main body 12 so as to face the recess 15, and the peripheral edge of the seal diaphragm 19 is the recess of the recess 15. It is hermetically welded to the surroundings. As a result, the seal diaphragm 19
Is capable of sealing the fluid to be measured and transmitting the pressure to the high-pressure enclosed liquid 17 in the recess 15. A second seal that closes the concave portion 16 and transmits the pressure of the fluid to be measured to the low-pressure enclosed liquid 18 enclosed inside the outer peripheral portion of the concave portion 16 of the main body 12 as described above. A low-pressure seal diaphragm 20 as a diaphragm is airtightly attached by welding. These seal diaphragms 19 and 20 are made of a thin metal plate such as stainless steel, and do not affect the measured differential pressure with respect to the displacement in the expansion direction and the displacement in the recess direction due to the temperature rise of the filled liquids 17 and 18. It is set to reduce the rigidity on the high-voltage side and the low-voltage side, and to balance them.

Inside the high pressure flange 13 side of the main body 12, there is provided a high pressure sealed liquid conducting passage 21. The high pressure sealed liquid conducting passage 21 includes a first passage 21A and a second passage 21B.
It is configured to include and. One end of the first passage 21A communicates with a high-pressure enclosed liquid inlet 21C formed in a part of the main body 12 toward the outside, the other end communicates with the recess 15, and one end of the second passage 21B A part of the main body 12 communicates with an outlet 21D formed toward the differential pressure detecting section 40, and the other end communicates with the recess 15. The first passage 21A and the second passage 21B are filled with the high-pressure enclosed liquid 17.

Inside the main body 12 on the low-pressure flange 14 side, a low-pressure sealed liquid conducting passage 22 is provided, and the low-pressure sealed liquid conducting passage 22 includes a first passage 22A and a second passage 22B.
It is configured to include and. One end of the first passage 22A communicates with a low pressure sealed liquid inlet 22C formed in a part of the main body 12 toward the outside, the other end communicates with the recess 16, and one end of the second passage 22B A part of the main body 12 communicates with an outlet 22D formed toward the differential pressure detector 40, and the other end communicates with the recess 16. The first passage 22A and the second passage 22B are filled with the low-pressure filled liquid 18. Note that the filled liquids 21C and 22C are filled with a required amount of the filled liquids 17 and 18 in predetermined portions such as the recesses 15 and 16, and then, for example, a steel ball 23 is pushed in to fill the filled liquids 17 and 18. Do not leak out.

An O-ring groove 24 is formed outside the seal diaphragm 19 on the side surface of the main body 12 on the high-pressure flange 13 side, and an O-ring 25, which is an elastic seal member, is formed in the O-ring groove 24. Is attached to the body 1
An O-ring groove 26 is formed outside the seal diaphragm 20 on the side surface of the second low pressure flange 14 side, and an O-ring 27 is mounted in the O-ring groove 26. Such O-rings 25 and 27 are used as the sealing surfaces 13A and 14A of the high pressure flange 13 and the low pressure flange 14, respectively.
(See FIG. 5), the fluid to be measured is sealed by being crushed by the O-ring grooves 24 and 26 and contacting the respective sealing surfaces 13A and 14A with a predetermined sealing surface pressure.

To fix the main body 12 and the mounting member 11 as described above, as shown in FIG. 3, a burring process is applied to a predetermined position of the mounting member 11 to form a cylindrical portion 11B. It is performed by abutting on a flat portion formed on a part of the main body 12 and welding.

As described above, the main body 12 is arranged between the high pressure flange 13 and the low pressure flange 14, and each of the flanges 13 and 14 is bolted via a spacer member 30 as shown in FIG. It is fixed to the main body 12 by tightening 31. As shown in FIGS. 2 and 5, each flange 1
3, 14 are formed in a rectangular parallelepiped shape. The two sides of the rectangular parallelepiped have the same length dimension, and the remaining one side has a different length dimension. The four surfaces orthogonal to the surface surrounded by the two sides having the same length dimension face each other. Surface 13F, 1
It is on the 4th floor.

Further, at the four corners of each of the flanges 13 and 14,
Bolt holes 13C and 14C and screw holes 13B and 14B are formed on the diagonals, respectively. Then, the spacer member 30 is aligned with, for example, the positions of the bolt holes 13C of the flange 13 and the screw holes 14B of the flange 14, and the bolts 31 are attached to the spacer members 3 from the bolt holes 13C of the flange 13.
0, and the flanges 14 and 14 are screwed into the screw holes 14B of the flange 14 to connect the flanges 13 and 14 to each other, and the flanges 13 and 14 and the main body 12 are fixed to each other. At this time, the facing surfaces 13 of the flanges 13 and 14
F, 14F and the facing surface 11A of the mounting member 11 are L
The size of the gap L is, for example, 0.5.
The distance is set to be a minute dimension within mm.

Further, as shown in FIG. 1, the distance H1 between the high pressure flange 13 and the low pressure flange 14 is determined by the length of the spacer member 30, and this distance H1, that is,
The length of the spacer member 30 is set to be larger than the width H2 of the main body 12, for example, 0.05 to 0.2 mm larger. As a result, the main body 12 is not directly in contact with the high-pressure flange 13 and the low-pressure flange 14, but is attached via the O-rings 25 and 27, which are elastic sealing members, respectively, whereby the main body 12 is in a floating state. Will be supported by.

As shown in FIG. 3, each of the flanges 13 and 14 has a pressure introducing port 13D for introducing a high pressure which is the first pressure of the fluid to be measured and a low pressure which is a second pressure. Is provided with a pressure introducing port 14D, and a drain discharge port 14G (see FIG. 2) that is normally closed and opened when necessary is provided. Further, as shown in detail in FIG. 5 in which the flanges 13 and 14 are viewed from the rear surface, the spacer member 3 is provided at the four corners of the inner surface of each of the flanges 13 and 14.
Two spacer guides 13E and 14E are provided, each of which serves as a guide when attaching 0. These spacer guides 13E and 14E are formed to have a predetermined height, and the sealing surface 1 is formed so as to surround the bolt holes 13C or the screw holes 13B from the end surfaces of the flanges 13 and 14, respectively.
It extends to the vicinity of 3A and 14A. However, the spacer guides 13E and 14E do not interfere (contact) with the main body 12. In addition, each spacer guide 13
E and 14E may be parallel to the facing surfaces 13F and 14F, or may be provided obliquely so that the tips of them approach each other.

Here, the fixing force of the bolt 31 is, for example,
If there are four M4 size screws, 6000-1000
0N, and this force is generated by the spacer member 30 and the O-ring 2.
It becomes the force to compress 5, 27 and. On the other hand, the O-ring 25,
The crushing force of 27 is 50 to 100 N when the outer diameter of the O-rings 25 and 27 is, for example, 28 mm, and the remaining force obtained by subtracting the crushing force of the O-ring from the fixing force of the bolt 31 compresses the spacer member 30. It becomes the power to do. Therefore, the force applied to the main body 12 is 50 to 100 N, and this force is
Compared with the conventional method of tightening and fixing the flange with bolts, it is reduced to about 1/80. For this reason, the distortion of the main body 12 becomes so small that it can be ignored, and there is no difference in weight depending on the tightening location.
Distortion of the main body 12 due to tightening of 3, 14 and further,
The output change of the measured value based on this disappears.

As shown in FIGS. 3 and 4, the differential pressure detecting section 40 includes a hermetic pedestal 41 as a pedestal and a sensor pedestal 4 attached to the hermetic pedestal 41 by adhesion or the like.
2, a sensor 43 attached to the sensor base 42 by adhesion or the like, and a cap 44 that covers the sensor base 42 and the sensor 43 and seals the high pressure side, and that is provided on the hermetic pedestal 41. The detection value detected by the differential pressure detecting unit 40 is sent to the circuit unit 52 which converts the detection value into a predetermined output signal. The circuit portion 52 is configured to include a substrate 55 made of, for example, a metal plate or glass epoxy, a connector 59, and the like, and an output signal from the circuit portion 52 is displayed by the display device 6.
It is sent to 0 and displayed.

The differential pressure detecting section 40 is a thin high-pressure pipe 4
5 and a large-diameter low-pressure pipe 46 to support the main body 12. That is, one end (the sensor 43 side) of the high-pressure pipe 45 penetrates the hermetic pedestal 41 and is inserted halfway into the filled liquid passage 42A opened in the sensor base 42, and the other end of the high-pressure pipe 45 has a sleeve. The second passage 21 </ b> B is opened in the main body 12 and is inserted halfway through the outlet 21 </ b> D of the second passage 21 </ b> B. The enclosed liquid conducting path 42A faces the space 53 formed by the cap 44 and the sensor base 42. And
The high pressure filling liquid 17 is supplied to the first passage 21A and the recess 1
5, the second passage 21B, the inside of the pipe 45, the filled liquid conducting passage 42A, and the space 53 are filled, so that one end of the sensor 43 is filled with the high pressure filled liquid 17.

On the other hand, one end of the low pressure pipe 46 penetrates the hermetic pedestal 41 and is in close contact with the lower end of the sensor base 42, and the other end is inserted into the sleeve 48 and
Outlet 22D of the second passage 22B opened in the main body 12
Is inserted halfway through. Further, between the sensor 43 and one end of the pipe 46, the sensor base 42 and the receiving base 54 are provided.
A space 53A surrounded by is formed. Then, the low-pressure sealed liquid 18 is supplied to the first passage 22A, the concave portion 16,
The second passage 22B, the interior of the pipe 46, and the space 53A are filled with each other, so that the other end side of the sensor 43 is filled with the low-pressure filled liquid 18.

The tips of the sleeves 47 and 48 are formed at a height exceeding the mounting member 11 from the main body 12, while the base ends are attached to predetermined positions of the main body 12 by, for example, projection welding. The inner diameters of the end portions of the sleeves 47 and 48 on the side of the mounting member 11 are inserted into the pipes 45 and 46 and then brazed to fix the pipes 45 and 46 and the sleeves 47 and 48. The enclosed liquids 17 and 18 are prevented from leaking between the outlets 21D and 22D of the main body 12 and the pipes 45 and 46. The inner diameter openings of the sleeves 47 and 48 are formed in a hollow shape so as to facilitate brazing.

In the hermetic pedestal 41, the high-pressure pipe 45, the low-pressure pipe 46, the electrode 49 for transmitting the capacitance change of the sensor 43 to the circuit portion 52, and the like are insulated and sealed (hermetically sealed) using glass 50. ing. Further, the sensor 43 and the electrode 49 are connected by a gold wire 51, and a change in capacitance from the sensor 43 is amplified and converted into a predetermined signal by the external circuit section 52, The value can be displayed on the display device 60. A plurality of electrodes 49 are provided, and each electrode 49
Connects the predetermined positions of the sensor 43 and the hermetic pedestal 41 to the circuit unit 52, respectively.

As described above, the sensor 43 detects a change in pressure by a change in capacitance, and the sensor base 42
It is provided by adhesion or the like on the pedestal 54 fitted in the inside of the. Further, as shown in detail in FIG. 4, the sensor 43 includes a silicon member 56 having a movable electrode portion (diaphragm), a fixed electrode member formed of an insulating material such as glass while sandwiching the silicon member 56 from both sides. 5
7 and 58 are provided, and a plurality of conduction holes 57A and 58A for allowing the high-pressure encapsulating liquid 17 and the low-pressure encapsulating liquid 18 to conduct toward the movable electrode portion are provided in the center and around them. Therefore, for example, the movable electrode portion may be pressed against the flat surface portion of the low-voltage side fixed electrode member 58 by being pressed by the high-pressure enclosed liquid 17, but in this case, the low-pressure enclosed liquid 1 is next.
When 8 is sent toward the movable electrode portion, the above-mentioned sticking force is large, and even if it cannot be sent from the central conductive hole 58A, it can be sent from the surrounding conductive hole 58A, so that the movable electrode portion is normally operated. The operation is ensured and the normal measurement of the sensor 43 is ensured. The case 5 that covers the differential pressure detection unit 40 is attached to the attachment member 11.

In order for the differential pressure detecting section 40 to accurately detect the differential pressure, it is necessary that the high-pressure side and the low-pressure side have the same amount of filled liquid. Therefore, in this embodiment, the high-pressure pipe 45 and the low-pressure pipe 46 have different inner diameters. That is, the space 53 in which the high-pressure side filled liquid 17 is filled and the space 53A in which the low-pressure side filled liquid 18 is filled in the differential pressure detection unit 40 have different volumes, and the space 53 on the high-pressure side is different. Is big. for that reason,
If the inner diameters of the high-pressure pipe 45 and the low-pressure pipe 46 having substantially the same length are made equal, the low-pressure filled liquid 1
The amount of the enclosed liquid of 8 becomes small. Therefore, the high-pressure pipe 45 is compared with the low-pressure pipe 46 by an amount equal to the difference between the amount of the filled liquid in the space 53 on the high pressure side and the amount of the filled liquid in the space 53A on the low pressure side in the differential pressure detection unit 40. The inner diameter is set to be small so that the internal volume becomes small. As a result, the high-pressure side filled liquid amount, which is the sum of the high-pressure side space 53 filled liquid amount and the high-pressure side space 53 filled liquid amount, is the low-pressure pipe 46 filled liquid amount and the low-pressure side space 53A. It becomes almost equal to the total amount of the enclosed liquid inside.

The relationship between the high pressure pipe 45 and the low pressure pipe 46 will be described. Now, on the high-pressure side and the low-pressure side, the difference in volume between the high-pressure pipe 45 and the low-pressure pipe 46 except for the internal volume of each pipe, that is, the high-pressure side space 53 and the high-pressure side sealed liquid conduction path 42A, Vd is the volume difference between the low-pressure side space 53A and the low-pressure side conduction path, the pipe length is Lp, and the cross-sectional area of the high-pressure pipe 45 is Ah, for low pressure. Assuming that the cross-sectional area of the pipe 46 is Al, the inner diameters of the high-pressure pipe 45 and the low-pressure pipe 46 are set to have the relationship expressed by the formula: Al-Ah = Vd / Lp (1).

Next, the sealing diaphragms 19 and 20, and
The interrelation between the filled liquids 17 and 18 and the pressure and temperature will be described. When the pressures of the fluid to be measured are applied to the seal diaphragms 19 and 20, respectively, these pressures are transmitted to the high pressure side and the low pressure side of the sensor 43 via the filled liquids 17 and 18, respectively, and the pressure difference is detected by the sensor 43. To be done. At this time, the displacement of the seal diaphragms 19 and 20 themselves when pressure is applied is very small. Also, fill liquid 1
Strictly speaking, 7 and 18 are slightly compressible although they are compressible, but their compressibility is small and they do not affect the measurement. Further, the capacitance change of the movable electrode portion (diaphragm) of the sensor 43 in the detection portion 40 is extremely small and can be ignored. On the other hand, the expansion of the enclosed liquid due to temperature is 0.1% per 1 ° C., and when the enclosed liquid amount is, for example, 200 μL, the temperature change of 50 ° C. causes a liquid amount change of 10 μL. Therefore, the pressure change due to the thermal expansion of the amount of filled liquid on the high pressure side and the low pressure side causes the rigidity of the seal diaphragms 19 and 20 to be 1 per 1 KPa.
When it is 5 μL, it becomes about 670 Pa. Therefore, if the difference in the amount of filled liquid on the high-pressure side and the low-pressure side is, for example, 10%,
67 Pa on the high pressure side and low pressure side when the temperature changes by 50 ° C
Therefore, a pressure difference of 1 is generated, which has a great influence on accurate pressure measurement.

As can be seen from the above description, it is necessary to make the amount of enclosed liquid as high as possible on the high pressure side and the low pressure side. In the present invention, by providing a difference in the cross-sectional area of the high-pressure pipe 45 and the low-pressure pipe 46 so as to have the relationship represented by the formula (1), there is a difference in the amount of enclosed liquid on the high pressure side and the low pressure side. Is configured so that there is no.

The display device 60 is provided in the case 5 as described above, and as shown in FIG.
The memory unit 62, the display unit 63, and the switch unit 64 are included. Then, when the switch unit 64 is pressed, the electric signal sent from the circuit unit 52 is calculated by the calculation unit 61 into a display value based on the correspondence table between the electric signal stored in the memory unit 62 and the differential pressure, The result is displayed on the display unit 63.

According to this embodiment, the following effects can be obtained.

(1) High-pressure pipe 45 which is the first pipe
The inner diameter of the high pressure side and the low pressure side are almost the same as each other only by making the inner diameter of the second pipe smaller than the inner diameter of the low pressure pipe 46 which is the second pipe. Therefore, in order to secure a volume equal to the volume of the high-pressure side space 53, the low-pressure side space 53A need not be expanded. As a result, the sensor base 42 does not have to be made large or high, and the differential pressure detection unit 40, and thus the differential pressure detector 1 can be downsized.

(2) The high-pressure pipe 45 and the low-pressure pipe 46 have sleeves 47 and 48 at the other ends, respectively.
While being inserted into the inside, the ends are inserted into the outlet 21D of the second passage 21B and the outlet 22D of the second passage 22B in the main body 12, and the sleeves 47 and 48 are fixed to the main body 12, so that the strength is improved. Is secured and a stable state can be secured. The inner diameters of the end portions of the sleeves 47 and 48 on the side of the mounting member 11 are brazed to fix the pipes 45 and 46 and the sleeves 47 and 48 after the pipes 45 and 46 are inserted. Since the tips of 47 and 48 are formed at a height exceeding the mounting member 11 from the main body 12, brazing of the sleeves 47 and 48 and the pipes 45 and 46 becomes easy.

(3) The silicon member 56 is sandwiched between the sensors 4
In the fixed electrode members 57 and 58 forming part 3, conductive holes 57A and 58A for conducting the high-pressure encapsulating liquid 17 and the low-pressure encapsulating liquid 18 toward the movable electrode portion (diaphragm) of the silicon member 56 are formed at the center. Since a plurality of surrounding liquids are provided, the movable electrode portion may stick to the flat surface portion of the low-voltage side fixed electrode member 58 by being pressed by the high-pressure enclosed liquid 17, and then the low-pressure enclosed liquid 18 moves. Even when the above-mentioned sticking force is large when it is attempted to be sent toward the electrode part and the low-pressure encapsulating liquid 18 can be sent from the surrounding conductive hole 58A even when it cannot be sent from the central conductive hole 58A, the movable electrode part The normal operation of the sensor 43 can be ensured, and the normal measurement of the sensor 43 can be ensured.

(4) The high-pressure flange 13 and the low-pressure flange 14 are fixed by tightening bolts 31 via a plurality of spacer members 30 formed longer than the thickness of the main body 12. The effect of tightening bolts 14 and 14 does not affect the body 12 side. as a result,
Since the main body 12 is prevented from being distorted when the flanges 13 and 14 are connected and fixed, it is possible to prevent a change in the output of the measured value caused by the influence of the local distortion of the main body 12, and thus the zero point. Change can be prevented.

(5) Since the main body 12 and the flanges 13 and 14 are supported via the O-rings 25 and 27,
If an excessive force is applied between the main body 12 and the flanges 13 and 14, the main body 12 and the flanges 13 and 14 may rotate. However, the facing surface 11A of the mounting member 11
And the facing surfaces 13F and 14F of the flanges 13 and 14,
Since it is installed with a minute gap within 0.5 mm,
When trying to rotate, the facing surfaces 13 of the flanges 13 and 14
F, 14F and the facing surface 11A of the mounting member 11 contact each other,
Since it does not rotate any further, it can be easily stopped at a minute rotation angle. Therefore, the flanges 13, 14
There is no fear of adversely affecting the measuring body instruments and the like attached to the pressure introducing ports 13D and 14D.

(6) The high-pressure flange 13 and the low-pressure flange 14 are each formed in a rectangular parallelepiped shape, and four surfaces orthogonal to a surface surrounded by two sides having the same length dimension in the rectangular parallelepiped shape are opposed surfaces. Since it is 13F and 14F,
Even when the fixing positions of the flanges 13 and 14 are changed in 90 degree units, the facing surface 11A of the mounting member 11 and the flange 13 are
The facing surface 13F and the facing surface 14F of the flange 14 can come into contact with each other, and as a result, they can be easily attached in any direction.

(7) Bolt holes 13C and 14C and screw holes 13 are provided at the four corners of the facing surfaces (inner side surfaces) of the flanges 13 and 14, respectively.
Two spacer guides 1 to surround B and 14B
Since 3E and 14E are provided respectively, when the spacer member 30 is sandwiched to fix the two flanges 13 and 14 together, the spacer member 30 can be easily positioned, which facilitates the connection work of the flanges 13 and 14. Becomes

Next, a second embodiment of the present invention will be described with reference to FIG. The present embodiment is a flowmeter 70 to which the differential pressure detector 1 of the first embodiment is attached.
In the differential pressure detector 1, the calculation unit 6 in the display device 60.
1, the electric signal sent from the circuit unit 52 is transferred to the memory unit 6
The calculation is performed based on the correspondence table between the electric signal and the differential pressure stored in No. 2, and the result is displayed on the display unit 63. However, in the second embodiment, the calculation unit of the display device 70A is used. The flow rate of an electric signal can be calculated.

That is, in the arithmetic unit of the display device 70A,
The electric signal sent from the circuit unit 52 is calculated based on the correspondence table between the electric signal and the flow rate stored in the memory unit, and the result is displayed on the display unit. Such a flow meter 70 includes a Venturi tube 75,
While connecting the low-pressure pressure inlet 14D of the differential pressure detector 1 to the part where the diameter of the venturi pipe 75 is reduced,
The high-pressure pressure inlet 13D is connected to a portion having a large diameter so that the pressures of two portions having different pressures can be detected. Then, as described above, the detected value is sent to the arithmetic unit of the display device 60A as a predetermined output signal in the circuit unit 52, the arithmetic unit obtains the flow rate, and the venturi pipe 7 is used.
It can be displayed as a flow rate of 5. Therefore, by connecting the flowmeter 70 to another pipe or the like, the flow rate of the pipe or the like can be easily known.

According to the second embodiment as described above,
In addition to the same effects as (1) to (7), there are the following effects. (8) For example, it is possible to detect the pressure at two different pressure positions with the differential pressure detector 1 and measure the flow rate based on this detected value. This makes it easy to measure the flow rate of pipes. Further, since the differential pressure detector can be downsized, the flow meter can be downsized.

Next, a third embodiment of the present invention will be described with reference to FIG. The present embodiment is a liquid level gauge 80 to which the differential pressure detector 1 of the first embodiment is attached.
In the third embodiment, for example, the arithmetic unit of the display device 80A can calculate the electric signal to the liquid surface height. That is, in the arithmetic unit of the display device 80A, the electric signal sent from the circuit unit 52 is calculated based on the correspondence table between the electric signal stored in the memory unit and the liquid surface, and the result is displayed on the display unit. It has become. Such a liquid level gauge 80 includes two connecting pipes 8 connected to the closed tank 85.
1 and 82, the high pressure pressure inlet 13D of the differential pressure detector 1 is connected to a high pressure portion of the closed tank 85, and the low pressure portion of the differential pressure detector 1 is connected to a low pressure portion. The pressure inlet 14D is connected so that the pressures at two different pressures can be detected. Then, as described above, the detected value is sent to the arithmetic unit of the display device 80A as a predetermined output signal in the circuit unit 52,
The liquid level height can be obtained by the calculation unit and displayed as the liquid level height of the closed tank 85. Therefore, the liquid level gauge 80
Is connected to, for example, the closed tank 85, the liquid level of the tank can be easily known.

According to the third embodiment described above,
In addition to the same effects as (1) to (7), there are the following effects. (9) Since the differential pressure detector 1 can detect the pressure at two different positions and measure the liquid level based on this detected value, the measurement of the liquid level in a closed tank in various processes etc. Will be easier. Further, since the differential pressure detector can be downsized, the liquid level gauge can be downsized.

The best configuration, method, and the like for carrying out the present invention have been disclosed above, but the present invention is not limited to these. That is, the present invention is mainly illustrated and described mainly with respect to a specific embodiment, but is not limited to the embodiment described above without departing from the technical idea and the scope of the object of the present invention. The person skilled in the art can make various modifications in terms of shape, material, quantity, and other detailed configurations. Therefore,
The shape disclosed in the above, the description limiting the material, etc. is described as an example to facilitate the understanding of the present invention, since it does not limit the present invention, those shapes,
The description with the name of the member from which some or all of the restrictions such as the material are removed is included in the present invention.

For example, in each of the aforementioned embodiments, the pressure introducing port 13 of the high pressure flange 13 and the low pressure flange 14 is used.
D and 14D are formed from the outer surface of each of the flanges 13 and 14 toward the back surface, but the invention is not limited to this. A hole may be formed along the front and back surfaces of the flanges 13 and 14 from the predetermined side surfaces 13F and 14F, and the hole may be formed to face the back surface from the middle.

Further, in each of the above-described embodiments, the high-pressure flange 13 and the low-pressure flange 14 are formed in a rectangular parallelepiped, and the facing surfaces 13F and 14F thereof are the flat surface portion 11A of the mounting member 11.
It was installed close to the back surface within 0.5 mm.
The interval of 5 mm or less includes a close contact state, and the flanges 13 and 14 may be provided in close contact with the mounting member 11. The point is that it is only necessary to prevent relative rotation between the flanges 13 and 14 and the main body 12.

Further, the mounting member 11 and each flange 13,
In forming the flanges 14 and 14 close to each other, projections having a predetermined height are provided at four corner positions of each of the flanges 13 and 14 and, for example, on one end face, and the projections are flat portions 11A of the mounting member 11. To be within 0.5mm,
The protrusion may be capable of contacting the flat surface portion 11A during rotation. The point is that it is only necessary to prevent relative rotation between the flanges 13 and 14 and the main body 12.

Further, in each of the above-mentioned embodiments, the first seal diaphragm 19 side is used for high pressure and the second seal diaphragm 20 side is used for low pressure, but the present invention is not limited to this.
The seal diaphragm 19 side may be used for low pressure and the second seal diaphragm 20 side may be used for high pressure.
The second term and the terms of high pressure and low pressure do not have a one-to-one correspondence. Further, the fluid to be measured is not necessarily limited to one fluid or two different fluids, and as can be understood from the second and third embodiments, either one fluid or two fluids can be understood. But it's okay.

In the first embodiment, the differential pressure detector 1 measures pressures at two different pressures, and the measured value sent as an electric signal is used as the calculation unit 6 of the display device 60.
1 is calculated and displayed as a differential pressure value. In the second embodiment,
The measurement value sent as an electric signal is calculated by the calculation unit of the display device 60 and displayed as a flow rate value. In the third embodiment, the measurement value sent as an electric signal is calculated by the calculation unit of the display device 80A, Although the liquid level height is displayed, these may be integrated together. That is, the memory unit 62 of the display device 60 of the differential pressure detector 1 includes the contents of the memory unit of the second embodiment (related to the flow rate) and the contents of the memory unit of the third embodiment (related to the liquid level). By the switch unit 64, each mode (differential pressure detector, flow meter, liquid level meter) can be selected, and when a predetermined mode is selected, the calculation unit displays the calculated value corresponding to the mode. You may If you do this,
One device can be used for multiple purposes.

Further, the conversion and calculation of the electric signal into the flow rate in the second embodiment and the conversion and calculation of the electric signal into the liquid level in the third embodiment are performed by the calculation unit of the circuit unit 52. You may go at 61.

[0057]

As described above, according to the differential pressure detector of the present invention, it is possible to set the inner diameters of the first pipe and the second pipe to different sizes so that the first pressure side It is possible to make the filled liquid amounts on the first pressure side and the second pressure side substantially the same. Further, since it is not necessary to increase the size of each member of the detection unit, the differential pressure detector can be downsized.

Further, according to the flow meter of the present invention, the pressure at two positions having different pressures can be detected by the differential pressure detector, and the flow rate can be measured based on the detected value.
It becomes easy to measure the flow rate of a pipe such as a solution or a gas pipe.

Further, according to the liquid level gauge of the present invention, it is possible to detect the pressure at two positions having different pressures by the differential pressure detector, and to measure the liquid level based on the detected value. It becomes easy to measure the liquid level of a closed tank in a process.

[Brief description of drawings]

FIG. 1 is a partially cutaway external view showing a differential pressure detector according to a first embodiment of the present invention.

FIG. 2 is an arrow view from the II direction in FIG.

FIG. 3 is a vertical cross-sectional view showing the differential pressure detector of the embodiment.

FIG. 4 is a vertical cross-sectional view showing a main part of the differential pressure detector of the embodiment.

FIG. 5 is a front view of the flange of the embodiment as viewed from the back surface.

FIG. 6 is a configuration diagram showing a main part of the embodiment.

FIG. 7 is a diagram showing a flowmeter of a second embodiment according to the present invention.

FIG. 8 is a view showing a liquid level gauge according to a third embodiment of the present invention and a usage state thereof.

FIG. 9 is an external view of a partial cross section showing a conventional differential pressure detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Differential pressure detector 10 Pressure receiving part 11 Mounting member 12 Main body 13 High pressure flange 14 which is a first pressure introducing member 14 Low pressure flange 17 which is a first pressure introducing member High pressure filled liquid 18 which is a first filled liquid 18 Second Low-pressure fill liquid 19 which is the fill liquid of No. 1 High-pressure seal diaphragm 20 which is the first seal diaphragm 20 Low-pressure seal diaphragm which is the second seal diaphragm 25 High-pressure O-ring 27 which is the elastic seal member 27 Low pressure which is the elastic seal member O-ring 30 Spacer 31 Bolt 40 Differential pressure detector 43 Sensor 60 Display 70 Flow meter 80 Level gauge

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoichi Abe             Nagano Keiki, 1-30-4 Higashimagome, Ota-ku, Tokyo             Within the corporation (72) Inventor Takashi Naratsu             Nagano Keiki, 1-30-4 Higashimagome, Ota-ku, Tokyo             Within the corporation F-term (reference) 2F014 AB02 BA03                 2F030 CA05                 2F055 AA40 BB05 CC02 DD01 DD05                       EE25 FF01 FF43 GG11 GG22                       HH05

Claims (4)

[Claims] 1. A main body having a predetermined thickness, first and second sealing diaphragms whose peripheral portions are airtightly fixed to two side surfaces of the main body at predetermined intervals, respectively, the main body and the first , The first and second sealed liquids filled in the gap formed between the first and second seal diaphragms and transmitting the first and second pressures through the respective seal diaphragms, and the first and second seal liquids. A first pressure introducing member that is provided to face the seal diaphragm and that introduces the first pressure to the first seal diaphragm, and a second pressure that is provided to face the second seal diaphragm and introduces the second pressure. Second
A differential pressure detector comprising a pressure introducing member and a detection unit for detecting a pressure difference between the first and second sealed liquids, wherein the first and second sealed liquids are first and second, respectively. The detection unit is filled with the second pipe, and the volumes of the first and second sealed liquids are substantially the same on the first pressure side and the second pressure side. A differential pressure detector characterized in that the inner diameters of the first and second pipes are set to different sizes. 2. The differential pressure detector according to claim 1, wherein the first and second sealed liquid sides are the first and second sealed liquid sides.
V is the difference in the volume of each pipe excluding the internal volume of each pipe.
d, assuming that the first and second pipe lengths are substantially equal, the pipe length is Lp, the cross-sectional area of the first pipe is Ah, and the cross-sectional area of the second pipe is Al. Two
The differential pressure detector is characterized in that the inner diameter of the pipe is set to have a relationship expressed by the formula: Al-Ah = Vd / Lp. 3. A flow meter, comprising the differential pressure detector according to claim 1 or 2. 4. A liquid level gauge, comprising the differential pressure detector according to claim 1 or 2.