JP2021025961A - Pressure detector, pressure transmitter, and pressure measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure detector which is easy to install and replace at a pressure measuring point and has good detection performance. A pressure detector of the present disclosure has a diaphragm, and has a pressure receiving portion filled with a fluid therein, and a transmission path that communicates with the pressure receiving portion and transmits the pressure received by the diaphragm by the fluid. It is characterized by including a pressure sensor for detecting the pressure transmitted by the fluid and a temperature sensor arranged in the pressure receiving portion. [Selection diagram] Fig. 2

Description

The present disclosure relates to pressure detectors, pressure transmitters and pressure measuring methods.

In order to monitor and control the state of the fluid to be measured in the piping and tank, the flow rate, liquid level, pressure and temperature of the fluid to be measured are measured. A differential pressure / pressure transmitter (also called a differential pressure transmitter) is used to measure the flow rate, liquid level, and pressure, and the temperature of a resistance temperature sensor or thermocouple is used to measure the temperature. A sensor is used.

A pressure transmitter (differential pressure transmitter) of a type called a remote seal type is generally used for measuring the liquid level and pressure of the fluid to be measured in the closed tank. FIG. 1 is a schematic view showing a remote seal type pressure transmitter 200. As shown in FIG. 1, the remote seal type pressure transmitter 200 has two wetted flanges 202 (pressure receiving portions), a main body 204, an amplification section 205, and two connecting the wetted flange 202 and the main body 204. It has a pressure guiding path 207. The wetted flange 202 includes a diaphragm 201 that receives the pressure of the fluid to be measured, and is attached to two attachment ports 103a and 103b (pressure measurement points) of the tank 102, respectively.

The main body 204 includes a pressure sensor 203 that detects a pressure difference between two locations. The amplification unit 205 is connected to the main body unit 204 and calculates a pressure signal from the pressure sensor 203. The pressure guiding path 207 is filled with an encapsulating liquid 206 which is a pressure transmission medium from the diaphragm 201 to the pressure sensor 203.

In this way, the wetted flange 202 is attached to the attachment port 103b on the bottom surface located at the lower part of the tank 102 and the attachment port 103a on the air layer portion located on the upper part of the tank 102, respectively, and these two attachment ports 103a and 103b are attached. By measuring the pressure difference of the fluid (gas, liquid) in the above, accurate liquid level measurement is performed.

The length of the pressure guiding path 207 is generally determined by the distance from the installation position of the main body 204 to each pressure measuring point to which the wetted flange 202 is attached. Typically, as described in Patent Document 1, the two pressure guiding paths are made to have the same length. This is to make the amount of the encapsulating liquid in each pressure guiding path the same in order to minimize the temperature influence error caused by the expansion and contraction due to the temperature change of the encapsulating liquid. Therefore, for example, if the pressure guiding path 207 connected to the liquid contact flange 202 for pressure measurement in the air layer portion is 10 m, the pressure guiding path 207 connected to the liquid contact flange 202 for pressure measurement in the bottom surface portion is also 10 m. It becomes.

The main body 204 is generally installed at a position equal to or lower than the mounting port 103b on the bottom surface in order to avoid the generation of a vacuum in Torricelli. For this reason, the distance between the installation position of the main body 204 and the mounting port 103b of the bottom surface is often shorter than the distance between the installation position of the main body 204 and the mounting port 103a of the air layer portion.

Regarding the temperature measurement of the fluid to be measured, in general, a dedicated mounting port 103c separate from the mounting port for the pressure transmitter is formed in the tank, and a temperature sensor 208 such as a resistance temperature detector or a thermocouple is mounted therein. The temperature of the measuring fluid is measured. For example, Patent Document 2 describes a method of providing a temperature measurement point of a tank without adding a mounting port by attaching a temperature sensor to a wetted flange and adding a temperature measuring point at the same time as mounting a differential pressure transmitter. ing.

JP-A-2003-344207 Japanese Unexamined Patent Publication No. 5-72016

In the pressure transmitter 200 as described above, the pressure guiding path 207 cannot be removed from the liquid contact flange 202 and the main body 204 because the product may break down due to leakage of the filling liquid 206. Therefore, when mounting the pressure transmitter 200, it is necessary to transport the wetted flange 202 to the respective mounting ports 103a and 103b with the wetted flange 202 and the main body 204 connected to the pressure guiding path 207. Therefore, for example, when the floors of the plant building are different between the lower part and the upper part of the tank 102, it is necessary to carry the wetted flange 202 for measuring the pressure of the air layer portion across the layers. However, since the pressure guiding path 207 is connected to the wetted flange 202 and the main body 204, additional work may be required to separately provide holes and stairs for transporting the wetted flange 202 on the floor of the plant building. is there.

If the wetted flange 202 (particularly the diaphragm 201) fails due to corrosion or physical damage to either the air layer or the bottom surface, removing the pressure guiding path 207 will lead to a product failure. Only the liquid flange 202 will be replaced for repair. In this case, for example, as in Patent Document 1, it is necessary to impart a structure and a function to the product so that the filling liquid does not leak when the wetted flange 202 is replaced, which complicates the structure and increases the manufacturing cost of the product. I will end up.

Further, the temperature influence error is such that even if the lengths of the two pressure guiding paths 207 are the same, there is a large difference between the temperature of the bottom surface and the temperature of the air layer, or sunlight is applied only to the pressure guiding path 207 on one side. It occurs when the hit temperature rises. Therefore, it is necessary to pay attention to the usage conditions and the installation position of the pressure guiding path 207. Further, the temperature influence error is remarkably generated because the amount of the filling liquid 206 increases as the pressure guiding path 207 becomes longer, which lowers the detection performance.

In order to solve the above problems, the present disclosure provides a detector that is easy to install and replace at a pressure measuring point and has good detection performance.

The pressure detector of the present disclosure has a diaphragm, a pressure receiving portion filled with a fluid inside, a transmission path communicating with the pressure receiving portion and transmitting the pressure received by the diaphragm by the fluid, and the fluid. It is characterized by including a pressure sensor for detecting the transmitted pressure and a temperature sensor arranged in the pressure receiving portion.

Further features relating to this disclosure will become apparent from the description herein and the accompanying drawings. In addition, the aspects of the present disclosure are achieved and realized by the combination of elements and various elements, the detailed description below, and the aspects of the appended claims.
The description of the present specification is merely a typical example, and does not limit the scope of claims or application examples of the present disclosure in any sense.

The detector of the present disclosure is easy to install and replace at a pressure measurement point, has a reduced temperature influence error due to expansion and contraction of the encapsulant, and has good detection performance.

Issues, configurations and effects other than the above will be clarified by the following description of the embodiments.

The schematic diagram which shows the remote seal type pressure transmitter. The cross-sectional schematic diagram which shows the detector which concerns on 1st Embodiment. The schematic diagram which shows the pressure transmitter which concerns on 1st Embodiment. FIG. 5 is a schematic cross-sectional view showing a detector according to a second embodiment. FIG. 6 is a schematic cross-sectional view showing a detector according to a third embodiment. FIG. 6 is a schematic cross-sectional view showing a detector according to a fourth embodiment.

[First Embodiment]
<Detector configuration example>
FIG. 2 is a schematic cross-sectional view showing the detector 17 according to the first embodiment. The detector 17 (pressure detector) includes a diaphragm 1, a pressure receiving unit 2, a pressure sensor 3, a sensor housing 4, a sensor stay 5, a bridge 6 (housing), a pressure guiding pipe 7 (transmission path), a filling liquid 8, and a temperature. It includes a sensor 9, airtight terminals 10a and 10b, a temperature signal line 11, lead wires 13a and 13b (first signal line and second signal line), a cover 14, an external connection component 15 (terminal), and a flange 16.

The pressure receiving unit 2 is a member installed at a pressure measuring point of the fluid to be measured. As shown in FIG. 2, the pressure receiving portion 2 is formed so that the cross-sectional shape is substantially U-shaped, and the opening (pressure receiving surface) of the pressure receiving portion 2 is a diaphragm 1 (“liquid contact diaphragm” or “pressure receiving diaphragm”. It is also covered with). The inside of the pressure receiving portion 2 is filled with the filling liquid 8, and when the diaphragm 1 receives the pressure from the fluid to be measured, the pressure is transmitted to the pressure sensor 3 by the filling liquid 8. The filling liquid 8 is a fluid such as silicone oil or propylene glycol. The volume of the encapsulating liquid 8 inside the pressure receiving portion 2 can be, for example, 1 mL to 20 mL, specifically about 3 mL.

The diaphragm 1 is fixed to the pressure receiving portion 2 while maintaining liquid tightness so as to prevent the filling liquid 8 from entering the fluid to be measured and to prevent the fluid to be measured from entering the filling liquid 8. The diameter of the diaphragm 1 is typically Φ88 mm, and the size of the diaphragm 1 does not have to be the same as the size of the attachment port provided at the pressure measurement point of the fluid to be measured. In the present embodiment, the surface of the diaphragm 1 on the fluid side to be measured may be referred to as the "front surface", and the surface of the pressure receiving portion 2 on the side of the fluid to be measured may be referred to as the "back surface".

As the temperature sensor 9, for example, a thermocouple or a resistance temperature detector can be used. The temperature sensor 9 is arranged at the center inside the pressure receiving portion 2, that is, at the center of the surface facing the back surface of the diaphragm 1. Examples of the method of fixing the temperature sensor 9 to the pressure receiving portion 2 include adhesion with an adhesive and mechanical fixing with screws.

Here, in Patent Document 2, since the position of the temperature sensor is deviated from the center of the wetted flange, there is a risk of leading to a temperature measurement error of the fluid to be measured due to heat dissipation from the surrounding piping. Further, since the temperature sensor of Patent Document 2 is exposed to the fluid to be measured, it is necessary to provide a mechanism for preventing corrosion. Further, since the lead wire is exposed to the atmosphere, it is necessary to protect it with a conduit or the like, and there is a concern that the structure becomes complicated.

On the other hand, in the present embodiment, since the temperature sensor 9 is arranged coaxially with the center of the diaphragm 1, it is possible to reduce the temperature measurement error of the fluid to be measured due to the heat radiation of the surrounding piping. Further, when the diaphragm 1 is a thin metal film, the thermal conductivity is high, so that the temperature of the fluid to be measured can be sufficiently detected by arranging the temperature sensor 9 near the back surface of the diaphragm 1, and the temperature to be measured can be sufficiently detected. It is not necessary to expose it to the fluid side. Further, since the inside of the pressure receiving portion 2 is hermetically sealed, the temperature sensor 9 is not affected by corrosion by the fluid to be measured and is protected from damage. Therefore, it is not necessary to separately provide a mechanism for preventing corrosion of the temperature sensor 9.

One end of the bridge 6 is joined to the pressure receiving portion 2 (opposite to the diaphragm 1). The bridge 6 has a tubular shape, and a space 12 inside the detector is formed inside the bridge 6. In the example shown in FIG. 2, the outer diameter of the bridge 6 is substantially the same as the outer diameter of the pressure receiving portion 2. The other end of the bridge 6 is joined to the sensor stay 5. In other words, one opening of the tubular bridge 6 is covered by the pressure receiving portion 2, and the other opening is covered by the sensor stay 5.

The sensor stay 5 is provided with a sensor housing 4 that houses the pressure sensor 3. As the pressure sensor 3, for example, a piezo type sensor or the like that can transmit the detection signal of the pressure sensor 3 over a long distance can be used.

The pressure receiving portion 2 is provided with a through hole 21, and one end of the pressure guiding pipe 7 (transmission path) is connected to the through hole 21. The pressure guiding pipe 7 extends along the longitudinal direction of the bridge 6 as a whole inside the bridge 6 (space 12 in the detector) and communicates with the sensor housing 4. In this way, the diaphragm 1, the pressure receiving portion 2, the sensor housing 4, and the pressure guiding pipe 7 form a closed space, and the closed space is filled with the filling liquid 8. The pressure received by the diaphragm 1 from the fluid to be measured is transmitted to the pressure sensor 3 in the sensor housing 4 by the filling liquid 8. Since the sensor housing 4 is arranged at the center of the sensor stay 5, the pressure guiding pipe 7 has a curved portion, but the sensor housing 4 is arranged so that the pressure guiding pipe 7 is linear. May be good.

The length of the pressure guiding pipe 7 along the longitudinal direction of the bridge 6 can be 100 cm or less, for example, 10 cm to 30 cm. The length of the bridge 6 is determined according to the length of the pressure guiding pipe 7. The lengths of the bridge 6 and the pressure guiding pipe 7 are set so that the pressure sensor 3 is arranged at a certain distance from the diaphragm 1. More specifically, the lengths of the bridge 6 and the pressure guiding pipe 7 may be such that the pressure sensor 3 does not become damaged at a temperature equal to or higher than the heat resistant temperature due to heat transfer from the fluid to be measured.

The heat transfer from the fluid to be measured will be described in more detail. When the temperature of the fluid to be measured is lower than the heat resistant temperature of the pressure sensor 3, no major problem occurs. However, the detector 17 can be used to measure a variety of fluids. Therefore, the temperature of the fluid to be measured is not always lower than the heat resistant temperature of the pressure sensor 3. In one example, the heat resistant temperature of the pressure sensor 3 is about 120 ° C. In one example, the temperature of the fluid under test (eg, hot pressurized water) can reach 300 ° C.

The heat of the fluid to be measured is transferred to the surface of the diaphragm 1 and the pressure receiving portion 2 in contact with the fluid to be measured by convective heat transfer. The heat received by the diaphragm 1 and the pressure receiving unit 2 is transferred to the pressure sensor 3 by heat conduction through the bridge 6, the sensor stay 5, and the like. Convective heat transfer generally refers to the transfer of heat between a fluid and a solid. On the other hand, heat conduction refers to the transfer of heat in a substance.

In a simple system, the state of convective heat transfer is expressed by the following equation (Newton's law of cooling):
Q = h ・ A ₁・ x ₁
Here, Q is the amount of heat, h is the heat transfer coefficient, A ₁ is the contact area _{of the fluid, and x 1} is the temperature difference between the fluid and the object. Here, the heat transfer coefficient is a value determined by the type of fluid, the presence or absence of flow, and its strength. The larger h, the easier it is for the heat of the fluid to be transferred to the solid. Different types of fluids have different heat transfer coefficients. On the other hand, even if the type of fluid is the same, h is small for a stationary fluid and large for a fluid with a flow. h increases as the flow rate of the fluid increases.

In a simple system, the state of heat conduction can be expressed by the following equation (Fourier's law):
_{Q = λ · x 2 · A} 2 / L
Here, Q is the amount of heat, λ is the thermal conductivity of the heat transfer path, x ₂ is the temperature difference between two points in the substance, A ₂ is the cross-sectional area of the heat transfer path, and L is the distance between the two points. Note that λ is a value unique to the object (material) that is the heat transfer path. Assuming that λ and A ₂ are constant, it can be seen that Q changes depending on L.

When the temperature of the fluid to be measured is the maximum possible temperature (expected maximum temperature) T1 _MAX , the condition that the temperature of the pressure sensor 3 is equal to or lower than the _{heat resistant temperature T3 MAX is examined.} First, the convective heat transfer, the temperature of the fluid contacting surface of the diaphragm 1 and the pressure receiving portion 2 (i.e., the highest temperature possible diaphragm 1 and the pressure receiving portion _{2) T2 MAX} is the equation of convective heat transfer T2 _MAX = _{T1 MAX} - Q _in / (h ・ A ₁ )
Will be. Here, Q _in is the amount of heat transferred from the fluid to be measured, and A ₁ is the contact area between the fluid to be measured and the diaphragm 1 and the pressure receiving portion 2.

And from the formula of thermal conductivity,
T3 _MAX ≧ T2 _MAX − (L ・ Q _in ) / (λ ・ A ₂ )
If L (distance between the diaphragm 1 and the pressure sensor 3) is determined so as to be, it can be seen that the temperature of the pressure sensor 3 is equal to or lower than the heat resistant temperature.

The above explanation is based on the simplest system. For more complex systems, Newton's law of cooling and Fourier's law are expressed by more complex equations. The length L may be set based on such a complex equation. When setting the length L, factors that affect heat conduction, such as the outside air temperature, the difference in cross-sectional area for each position of the heat transfer path, the difference in material for each position of the heat transfer path (= difference in λ), etc. May be considered.

The internal volume of the pressure guiding pipe 7 can be, for example, 0.1 mL to 1 mL, and specifically, about 0.5 mL. As described above, the pressure sensor 3 is provided on the detector 17 itself attached to the pressure measurement point. Since the detector 17 has such a configuration, the distance between the diaphragm 1 and the pressure sensor 3 becomes short, so that the length of the pressure guiding pipe 7 for transmitting the pressure can be shortened. As described above, since the pressure guiding pipe 7 has a shorter length than the pressure guiding path 207 shown in FIG. 1 and the volume of the filling liquid 8 in the pressure guiding pipe 7 is also small, the filling liquid 8 due to a temperature change Volume change (expansion and contraction) is also small. As a result, it is possible to reduce the detection error caused by the volume change of the filling liquid 8 due to the temperature change.

The cover 14 is joined to the sensor stay 5, and an external connection component 15 is provided inside. As the external connection component 15, for example, an electric wire connection connector or a terminal block can be used. A through hole 22 is provided in the sensor stay 5, whereby the inside of the bridge 6 and the inside of the cover 14 communicate with each other to form a space 12 inside the detector.

An airtight terminal 10a is provided in the pressure receiving unit 2 in order to take out the signal detected by the temperature sensor 9 from the closed space in the pressure receiving unit 2 to the outside. The airtight terminal 10a penetrates the pressure receiving portion 2 and is joined so as to be exposed inside and outside the pressure receiving portion 2. As the airtight terminal 10a, for example, a hermetic terminal or the like can be used. The temperature sensor 9 is provided with a temperature signal line 11 that outputs a temperature signal to the outside, and the airtight terminal 10a and the temperature signal line 11 are connected by soldering or the like. A lead wire 13a (first signal line) is connected to the airtight terminal 10a.

An airtight terminal 10b is provided in the sensor housing 4 in order to take out the pressure signal detected by the pressure sensor 3 from the closed space inside the sensor housing 4. The airtight terminal 10b penetrates the sensor housing 4 and is joined so as to be exposed inside the cover 14 (detector internal space 12). As the airtight terminal 10b, for example, a hermetic terminal or the like can be used. A lead wire 13b (second signal line) is connected to the airtight terminal 10b. Further, the sensor stay 5 is formed with a through hole 22 for leading the lead wire 13a connected to the airtight terminal 10a into the cover 14.

The lead wires 13a and 13b are conducted to the external connection component 15 in the cover 14. In this way, the lead wire 13a of the temperature sensor 9 and the lead wire 13b of the pressure sensor 3 are stored in the detector 17 and are not exposed to the atmosphere. As a result, the lead wires 13a and 13b can be protected from damage and stains.

The flange 16 is arranged around the pressure receiving portion 2 and is used for connecting a mounting port (not shown) provided at a measurement point such as a tank to the detector 17. The flange 16 has a plurality of bolt through holes for bolting to the mounting port.

<Configuration example of pressure transmitter>
FIG. 3 is a schematic view showing the pressure transmitter 100 according to the first embodiment. As shown in FIG. 3, in the present embodiment, a pressure transmitter 100 (differential pressure transmitter) for measuring the pressure in the tank 102 containing the fluid to be measured 101 will be described as an example.

The pressure transmitter 100 includes two detectors 17 (detectors 17a and 17b), two electric wires 18 (electric wires 18a and 18b), and a processing unit 19 (processing device).

The tank 102 is provided with mounting ports 103a and 103b (pressure measurement points) for mounting the detectors 17a and 17b, respectively. The mounting port 103a is provided at the upper part of the side surface of the tank 102 so that the pressure of the air layer portion can be measured, and the mounting port 103b is provided at the lower part of the side surface of the tank 102 so that the pressure at the bottom of the fluid 101 to be measured can be measured. Provided. The flanges 16 of the detectors 17a and 17b are connected to the mounting ports 103a and 103b by, for example, screwing. As a result, the surface of the diaphragm 1 of the detector 17a comes into contact with the air layer portion, and the surface of the diaphragm 1 of the detector 17b comes into contact with the fluid to be measured.

For example, after the detector 17a is connected to the attachment port 103a, the electric wire 18a is connected to the external connection component 15 of the detector 17a.

The processing unit 19 has two external connection components 151a and 151b, and the electric wire 18a connected to the external connection component 15 of the detector 17a is connected to the external connection component 151a. Since the same applies to the detector 17b, the description thereof will be omitted.

There is no limitation on the installation position of the processing unit 19, and the lengths of the electric wires 18a and 18b can be determined according to the distance between the installation position of the processing unit 19 and the positions of the detectors 17a and 17b, respectively.

Like the pressure transmitter 200 shown in FIG. 1 and the pressure transmitter described in Patent Document 1, the length of the pressure guiding path is set according to the distance from the installation position of the main body to the pressure measurement point of the air layer. In this case, if the lengths of the two pressure guiding paths are the same, the pressure guiding paths connected to the wetted contact flange for the bottom surface portion have a large excess length. As a result, it becomes necessary to consider how to install the extra length of the pressure guiding path.

On the other hand, in the pressure transmitter 100 of the present embodiment, for example, when the processing unit 19 is arranged near the attachment port 103b of the tank 102, the length of the electric wire 18b connected to the detector 17b at the bottom of the tank 102 is set to the length of the tank 102. It can be shorter than the wire 18a connected to the upper detector 17a. As described above, since it is not necessary to make the lengths of the electric wires 18a and 18b the same, no surplus of the electric wires 18 is generated. When the processing unit 19 is arranged at a position away from the tank 102, the electric wire 18b may be extended.

As the electric wire 18, for example, a multi-core cable having a sufficient number of lead wires for transmitting a temperature signal and a pressure signal can be applied. The electric wire 18 is connected by screwing to the terminal block or connecting a connector such as M12, depending on the types of the external connecting parts 15 and 151.

Here, for example, in the conventional pressure transmitter 200 shown in FIG. 1, it is necessary to attach the wetted flange, the pressure guiding path, and the main body to the pressure measuring point in a connected state, which complicates the installation work. was there. On the other hand, in the pressure transmitter 100 of the present embodiment, since each detector 17 can be attached to the pressure measurement point and then connected to the processing unit 19 by the electric wire 18, the installation work becomes simple.

Further, since the pressure transmitter 100 of the present embodiment does not have a pressure guiding path in which the filling liquid is sealed, each detector 17 and the processing unit 19 can be wirelessly connected. This makes it easier to install the pressure transmitter 100 as compared with the case where the electric wire 18 is used.

As described above, by installing the detector 17 at the pressure measuring point and connecting it to the processing unit 19 by the electric wire 18, it is possible to measure the liquid level, pressure and temperature of the fluid 101 to be measured in the tank 102. it can. The diaphragm 1 of the detector 17 receives pressure at each pressure measurement point, the pressure is transmitted by the filling liquid 8, and the pressure sensor 3 detects the pressure. At the same time, the temperature sensor 9 arranged on the back side of the diaphragm 1 detects the temperature at each pressure measurement point.

Although not shown, the processing unit 19 processes the amplification unit that amplifies the pressure signal and the temperature signal received from the detector 17, the amplified pressure signal and the temperature signal, and calculates the pressure value (differential pressure). It is provided with a calculation unit for performing operation, a display unit for displaying a pressure value, and a storage unit (for example, memory, storage, etc.) for storing data required for processing by the calculation unit. The processing by the amplification unit and the calculation unit can be performed by a processor such as a CPU or an MPU, for example. A program for performing processing by the amplification unit and the calculation unit is stored in the storage unit, and the processing is executed when the program is read out by the amplification unit and the calculation unit.

The above calculation unit converts the pressure signal from the detector 17 into an electromagnetic signal of differential pressure and pressure (first electromagnetic signal), and the temperature signal is an electromagnetic signal of temperature (second electromagnetic signal). Is converted to. These electromagnetic signals include current signals and the like. Further, the calculation unit calculates the pressure value (differential pressure) based on the electromagnetic signal and outputs it to the display unit. The relationship between the temperature change of the fluid to be measured 101 and the expansion / contraction amount of the filling liquid 8 may be obtained in advance at the time of design and stored in the storage unit as a correction table. This makes it possible to correct the temperature influence error caused by the volume change of the filling liquid 8 due to the temperature change based on the temperature signal from the temperature sensor.

The processing unit 19 is connected to the external system 104 by wire or wirelessly, and transmits the generated electromagnetic signal (for example, a current signal of 4 mA to 20 mA) to the external system 104.

The external system 104 is, for example, a computer terminal such as a general-purpose computer, a smartphone, a tablet, or a mobile phone. Although not shown, the external system 104 includes a processing unit that processes electromagnetic signals, a storage unit that stores various data such as processing results by the processing unit, and a display unit that displays various data.

The processing unit of the external system 104 converts, for example, an electromagnetic signal received from the processing unit 19 of the pressure transmitter 100 into a digital signal, and outputs image data (table, graph, etc.) showing a measurement result based on the digital signal. Generate and display on the display.

In the above, an example in which the processing unit 19 is arranged near the tank 102 and is connected to the detector 17 by the electric wire 18 has been described, but the present invention is not limited to this. For example, a circuit board may be connected to the external connection component 15 of the detector 17 and used as the processing unit 19.

In the present embodiment, an example in which the detector 17 is used for the pressure transmitter 100, which is a differential pressure transmitter, has been described, but the present invention is not limited to this, and the detector of the present embodiment is used for various devices that require pressure detection. 17 can be applied.

<Technical effect>
As described above, in the detector 17 of the present embodiment, the pressure sensor 3 is provided in the detector 17 itself attached to the pressure measurement point, and the distance between the pressure receiving diaphragm 1 and the pressure sensor 3 becomes short. , The length of the pressure guiding pipe 7 for transmitting the pressure can be shortened. As a result, the volume of the filling liquid 8 in the pressure guiding pipe 7 becomes small, so that the volume change of the filling liquid 8 due to the influence of the temperature change also becomes small. Therefore, it is possible to prevent the pressure sensor 3 from detecting the pressure due to the volume change of the filling liquid 8, so that the detection error can be reduced.

Further, in the detector 17, since the temperature sensor 9 is arranged near the back surface of the diaphragm 1, by installing the detector 17 at the pressure measurement point, it is possible to increase the number of temperature measurement points at the same time. This has the effect of contributing to the reduction of the instruments used by the user.

Further, since the temperature sensor 9 is arranged on the back surface side of the diaphragm 1 and is not exposed to the fluid to be measured, it is not necessary to consider corrosion by the fluid to be measured, and the temperature sensor 9 can be arranged at a position coaxial with the center of the diaphragm 1. Therefore, it is possible to reduce the temperature measurement error of the fluid to be measured due to the heat radiation of the surrounding piping.

Since the pressure transmitter 100 of the present embodiment can be connected to the electric wire 18 after the detector 17 and the processing unit 19 are arranged, it is not necessary to install the pressure transmitter 100 in a state where the electric wire 18 and the processing unit 19 are connected. Installation work is easy. Further, since the length of the electric wire 18 can be selected according to the position of the processing unit 19, it is not necessary to secure a space for accommodating the surplus electric wire 18.

As a result of reducing the pressure guiding path, the amount of the filling liquid can be significantly reduced, which has the effect of reducing the temperature influence error.

Further, when one detector 17 fails due to corrosion or physical damage caused by the fluid to be measured, the failure does not spread to the other detector 17 and the processing unit 19.

Since the electric wire 18 is removable, it is not necessary to provide the product with a mechanism that prevents the encapsulating liquid from leaking as in Patent Document 1. Further, since the failed detector 17 can be replaced individually, it is not necessary to replace all the pressure transmitters 100, and the user cost burden at the time of failure can be reduced.

[Second Embodiment]
In the detector 17 of the first embodiment, the temperature sensor 9 is arranged on the back side of the diaphragm 1 in the pressure receiving unit 2. Therefore, in the second embodiment, an example of another arrangement of the temperature sensor 9 will be described. The same components as those in the first embodiment are designated by the same reference numerals, and redundant description will be omitted.

<Detector configuration example>
FIG. 4 is a schematic cross-sectional view showing the detector 17 according to the second embodiment. As shown in FIG. 4, the recess of the pressure receiving portion 2 is provided with a housing hole 20 substantially parallel to the diaphragm 1, and the temperature sensor 9 is housed in the housing hole 20. The opening of the accommodating hole 20 is closed by the flange 16. The accommodating hole 20 and the detector internal space 12 communicate with each other through the through hole 23. The lead wire 13a is connected to the temperature sensor 9, is led out from the through hole 23 to the detector internal space 12, and extends to the external connection component 15 inside the cover 14.

<Technical effect>
With such a configuration, it is not necessary to provide the airtight terminal 10a for extracting the temperature signal from the temperature sensor 9 in the encapsulating liquid 8 as in the first embodiment, so that the manufacturing cost can be reduced and the work at the time of manufacturing can be performed. It can also improve sex.

[Third Embodiment]
In the second embodiment, a through hole 23 for communicating the accommodating hole 20 of the pressure receiving unit 2 and the detector internal space 12 is provided, and the lead wire 13a connected to the temperature sensor 9 is led out to the detector internal space 12. Was explained. Therefore, in the third embodiment, in order to secure a large insertion length of the temperature sensor 9 into the accommodating hole 20, the lead wire 13a is led out from the opening of the accommodating hole 20 without providing the through hole 23. An example will be described.

<Detector configuration example>
FIG. 5 is a schematic cross-sectional view showing the detector 17 according to the third embodiment. As shown in FIG. 5, the temperature sensor 9 is housed in the housing hole 20 as in the second embodiment. The flange 16 is provided with a notch 24 that communicates with the accommodating hole 20. The lead wire 13a is led out from the opening of the accommodating hole 20, that is, the side surface of the pressure receiving portion 2, and reaches the detector internal space 12 via the notch 24 and the through hole 25 provided in the bridge 6. To do. A cover 26 is provided to protect the lead wire 13a from the outside atmosphere.

<Technical effect>
With such a configuration, the area occupied by the lead wire 13a in the accommodating hole 20 can be reduced as compared with the second embodiment, so that it is possible to secure a large insertion length of the temperature sensor 9. Become. This is particularly effective when a sheath-type thermocouple, a resistance temperature detector, or the like, which requires a predetermined minimum insertion length, is used as the temperature sensor 9.

[Fourth Embodiment]
In the fourth embodiment, another example of the arrangement of the temperature sensor 9 will be described.
<Detector configuration example>
FIG. 6 is a schematic cross-sectional view showing the detector 17 according to the fourth embodiment. As shown in FIG. 6, the pressure receiving portion 2 is provided with an accommodating hole 27 communicating with the detector internal space 12. The temperature sensor 9 is inserted into the accommodating hole 27 so as to be substantially perpendicular to the diaphragm 1. Since the temperature sensor 9 is arranged in the detector internal space 12, the lead wire 13a can be easily connected.

<Technical effect>
With such a configuration, it is not necessary to provide an airtight terminal 10a for extracting a temperature signal from the temperature sensor 9. Further, as compared with the second embodiment and the third embodiment, the processing of the accommodating hole 27 and the installation of the temperature sensor 9 are simpler, so that the manufacturing cost can be reduced and the workability at the time of manufacturing is improved. You can also do it.

[Modification example]
The present disclosure is not limited to the embodiments described above, but includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present disclosure in an easy-to-understand manner, and does not necessarily have all the configurations described. In addition, a part of one embodiment can be replaced with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of another embodiment with respect to a part of the configuration of each embodiment.

1 ... Diaphragm 2 ... Pressure receiving part 3 ... Pressure sensor 4 ... Sensor housing 5 ... Sensor stay 6 ... Bridge 7 ... Pressure guiding pipe 8 ... Filling liquid 9 ... Temperature sensor 10a, 10b ... Airtight terminal 11 ... Temperature signal line 12 ... Detector Inner space 13a, 13b ... Lead wire 14 ... Cover 15, 151 ... External connection part 16 ... Flange 17 ... Detector 18 ... Electric wire 19 ... Processing unit 20, 27 ... Accommodating holes 21-23, 25 ... Through hole 24 ... Notch Part 26 ... Cover 100, 200 ... Pressure transmitter 101 ... Fluid 102 to be measured ... Tank 103a, 103b, 103c ... Mounting port 104 ... External system

Claims (14)

A pressure receiving part that has a diaphragm and is filled with fluid inside,
A transmission path that communicates with the pressure receiving portion and transmits the pressure received by the diaphragm by the fluid.
A pressure sensor that detects the pressure transmitted by the fluid, and
A pressure detector comprising: a temperature sensor arranged in the pressure receiving portion. The pressure detector according to claim 1, wherein the length of the transmission path is 100 cm or less. The pressure detector according to claim 1, wherein the temperature sensor is arranged coaxially with the center of the diaphragm. The pressure detector according to claim 1, wherein the temperature sensor is arranged near the back surface of the diaphragm. The pressure receiving portion further includes an accommodating hole.
The pressure detector according to claim 1, wherein the temperature sensor is housed in the storage hole. The first signal line connected to the temperature sensor and
A second signal line connected to the pressure sensor and
A housing connected to the pressure receiving portion and accommodating the first signal line and the second signal line,
The pressure detector according to claim 1, further comprising a first signal line and a terminal connected to the second signal line, which is housed in the housing. The pressure sensor is arranged at a certain distance from the diaphragm so as not to exceed the heat resistant temperature due to heat transfer from the fluid to be measured, and the constant distance is determined by the length of the transmission path. The pressure detector according to claim 1. The pressure detector according to claim 1 and
The detection signal of the pressure sensor and the detection signal of the temperature sensor are received, the detection signal of the pressure sensor is converted into a first electromagnetic signal, and the detection signal of the temperature sensor is converted into a second electromagnetic signal. A pressure transmitter characterized by comprising a processing unit for processing. 8. Claim 8 is characterized in that the pressure detector is connected to the processing unit, and an electric wire for outputting a detection signal of the pressure sensor and a detection signal of the temperature sensor from the pressure detector to the processing unit is further provided. The pressure transmitter described in. The pressure transmitter according to claim 8, wherein the processing unit calculates a pressure value based on the first electromagnetic signal. The pressure transmitter according to claim 10, wherein the processing unit corrects the pressure value based on the second electromagnetic signal. With the plurality of pressure detectors
The pressure transmitter according to claim 9, further comprising the plurality of electric wires connecting the plurality of pressure detectors and the processing unit. The pressure transmitter according to claim 8, wherein the processing unit outputs the first electromagnetic signal and the second electromagnetic signal to an external system. The pressure measuring method using the pressure detector according to claim 1.
To calculate the pressure value from the detection signal of the pressure sensor,
A pressure measuring method including correcting the pressure value based on a detection signal of the temperature sensor.

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