JP5899576B2 - Pressure type level meter - Google Patents

Description

  The present invention relates to a pressure type level meter that measures the liquid pressure of a storage tank or a pipe for storing a liquid and measures the height of the liquid level.

  Conventionally, a pressure type level meter that measures the height of the liquid level of a liquid stored in a storage tank or the like based on the liquid pressure in the storage tank or the like has been used. As this type of technology, there is one that uses a gauge pressure (relative pressure) sensor to calculate the difference between the hydraulic pressure and the external pressure to obtain only the hydraulic pressure. However, in this technique, it is necessary to introduce outside air into the sensor due to the measurement method, which causes condensation. When dew condensation occurs in the sensor, rust may be generated on a substrate or the like provided in the sensor. As a result, the life of the sensor is shortened and cannot be detected properly. There exists a thing of the patent document 1 which shows the following as a technique which suppresses generation | occurrence | production of such condensation.

  The submerged hydraulic water level sensor described in Patent Document 1 includes a pressure detection element, a signal processing circuit, and an air tube. The pressure detection element detects an external pressure based on a change in capacitance between a moving electrode formed on a diaphragm that is deformed by receiving an external pressure and a fixed electrode that is spaced apart from the moving electrode. The signal processing circuit performs calculation processing of an output signal from the pressure detection element. The air tube hermetically accommodates the pressure detection element and the signal processing circuit unit in a housing, and introduces air into the housing. In such a submerged hydraulic water level sensor, the gap between the moving electrode and the fixed electrode and the open end of the air tube are hermetically connected. Air is introduced from the air tube into the gap between the moving electrode and the fixed electrode through the relay tube. Thereby, the external pressure (water pressure) acting on the diaphragm is detected.

Japanese Patent Laid-Open No. 10-111163

  Here, in the technique described in Patent Document 1, external pressure (water pressure) is directly applied to one surface of the diaphragm, and the other surface is exposed to the outside air. Therefore, the occurrence of condensation cannot be completely prevented. Further, when condensation occurs and moisture adheres to the diaphragm, an error is included in the pressure acting on the diaphragm, so that there is a possibility that the water level of the liquid cannot be detected with high accuracy.

  In view of the above problems, an object of the present invention is to provide a pressure type level meter that can reliably prevent the occurrence of condensation.

In order to achieve the above object, the characteristic configuration of the pressure type level meter according to the present invention is:
A cylindrical member that is formed into a cylindrical shape having openings at both ends, and outside air is introduced to the side of one opening;
A diaphragm that closes the other opening of the cylindrical member and deforms according to the hydraulic pressure;
A valve body that can be deformed so as to close the one opening and form a sealed space together with the diaphragm inside the cylindrical member, and to maintain an equal pressure outside and the pressure in the sealed space;
It is in the point equipped with.

  With such a characteristic configuration, the diaphragm is sandwiched between the liquid in a liquid storage tank or a pipe provided with a pressure type level meter and the sealed space, and is not directly exposed to the outside air. For this reason, the diaphragm can be shielded from the outside air, and the humidity inside the sealed space can be stably maintained.Therefore, even if there is a temperature difference between the liquid in the liquid storage tank or piping, etc. and the outside air, dew condensation occurs. Can be reliably prevented. Therefore, the height of the liquid level can be detected with high accuracy.

  The valve body can be formed of a film having a surface area larger than the opening area of the one opening.

  With such a configuration, when the pressure in the sealed space fluctuates, the amount of displacement of the membrane can be made smaller than the amount of displacement of the diaphragm, so that the degree of freedom of the material of the membrane and the pasting structure can be increased. It becomes possible. For this reason, it is preferable that the valve body is provided so as to be loosened with respect to one opening. Therefore, even when there is a pressure difference between the pressure outside the sealed space and the pressure in the sealed space, the pressure difference can be allowed by the deformation of the valve body. Further, since the valve body is provided by being slackened, the valve body can be easily deformed according to the pressure difference between the pressure outside the sealed space and the pressure in the sealed space.

  Further, it is preferable that the valve body is plastically deformable in accordance with a differential pressure between the outside pressure and the pressure in the sealed space.

  With this configuration, when the valve body is deformed so as to maintain the pressure outside the sealed space and the pressure in the sealed space equal, elastic force does not continue to act on the valve body. Drag can be reduced. Therefore, the valve body can be easily deformed.

  Further, it is preferable that the cylindrical member is configured so that an opening area of the one opening is wider than an opening area of the other opening.

  With such a configuration, it is possible to reduce the force acting on the valve body that closes the one opening based on the hydraulic pressure acting on the diaphragm that closes the other opening. Therefore, it becomes easy for the valve body to maintain the outer pressure and the pressure in the sealed space equally.

The sealed space is preferably filled with air or nitrogen gas .

  With such a configuration, the heat-insulating effect can be enhanced because the sealed space has a large air layer. That is, even if there is a temperature difference between the temperature outside the diaphragm and the temperature outside the valve body, it is difficult for the other temperature to be transmitted to each of the diaphragm and the valve body by the sealed space. The prevention effect can be enhanced.

It is a figure which shows the example of application of a pressure type level meter. It is a fragmentary sectional view showing a pressure type level meter typically. It is a figure which shows typically about the change of a valve body. It is a figure which shows the valve body which concerns on other embodiment. It is a figure which shows the valve body which concerns on other embodiment. It is a figure which shows the valve body which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. The pressure type level meter 10 according to the present invention has a function of accurately detecting the liquid level of the liquid stored in the liquid storage tank. Hereinafter, it demonstrates using drawing.

  FIG. 1 is a diagram schematically showing a liquid storage tank (hereinafter referred to as “tank”) 1 used as a container for storing liquid. Such a tank 1 is provided in a plant, and a liquid used in the plant is stored. The tank 1 includes a storage unit 2 that stores liquid and a discharge port 3 that discharges the liquid stored in the tank 1 from the storage unit 2. When the stored liquid is discharged, the amount of liquid stored in the tank 1 decreases. However, the pressure type level meter 10 according to the present invention is partially inserted into the lower side surface (wall surface close to the bottom) of the tank 1. The amount of the liquid is detected based on the pressure corresponding to the amount of the liquid.

  FIG. 2 shows a partial cross-sectional view of the pressure type level meter 10. The pressure type level meter 10 includes a cylindrical member 20, a diaphragm 30, and a valve body 40. The cylindrical member 20 is formed in a cylindrical shape having openings 20A and 20B at both ends. Both end portions are end portions on both axial sides of the cylindrical member 20. The cylindrical member 20 is configured with openings at both ends in the axial direction. Therefore, the cylindrical member 20 is configured in a state where one opening 20A (hereinafter referred to as “opening 20A”) and the other opening 20B (hereinafter referred to as “opening 20B”) communicate with each other. The

  In the present embodiment, the cylindrical member 20 is configured such that the opening area of the opening 20A is wider than the opening area of the opening 20B. Thereby, the fluctuation | variation based on the pressure change of the opening part 20B can be made small apparently in the opening part 20A. As shown in FIG. 2, it may be configured to increase in steps from the opening 20B to the opening 20A, or may be configured to gradually increase in, for example, an arc shape or a straight line shape.

  Moreover, the cylindrical member 20 is provided in the state by which external air is introduced into the opening part 20A side. Outside air is air outside the tank 1. In the present embodiment, for example, the opening 20A is inserted in a state of protruding from the tank 1. That is, the entire cylindrical member 20 is not inserted into the tank 1, but at least a part of the cylindrical member 20 is attached to protrude from the outer surface of the tank 1. In this embodiment, a part having an outer diameter substantially equal to the opening 20B, that is, a part from the opening 20B to the length L along the axial direction is inserted into the hole 4 formed on the lower side surface of the tank 1, The thread formed on the inner peripheral surface of the hole 4 is fastened and fixed.

  The diaphragm 30 closes the opening 20B of the cylindrical member 20 and deforms according to the hydraulic pressure. The diaphragm 30 is configured with an outer diameter slightly smaller than the inner diameter of the opening 20B, and is fitted in the opening 20B in a liquid-tight manner. Therefore, even when the opening 20B into which the diaphragm 30 is fitted is inserted into the hole 4 of the tank 1 up to the length L, the liquid in the tank 1 is configured not to permeate the opening 20A. The hydraulic pressure is a pressure received from the liquid in the tank 1. Therefore, the diaphragm 30 is deformed according to the pressure received from the liquid without allowing the liquid in the tank 1 to permeate the opening 20A. In other words, it is elastically deformed toward the center in the axial direction when viewed from the opening 20B.

  The valve body 40 closes the opening 20 </ b> A and forms a sealed space 50 together with the diaphragm 30 inside the cylindrical member 20. That is, the sealed space 50 is configured by the valve body 40, the diaphragm 30, and the inner peripheral surface of the tubular member 20. As described above, the diaphragm 30 is fitted in the opening 20B of the tubular member 20 in a liquid-tight manner. On the other hand, the valve body 40 is also liquid-tightly provided in the opening 20 </ b> A of the tubular member 20. Accordingly, the sealed space 50 is a space that is blocked from the outside. In the present embodiment, the assembly of the diaphragm 30 and the valve body 40 to the tubular member 20 is performed under normal pressure and normal temperature and humidity, so that the sealed space 50 is filled with normal temperature and normal humidity air. become.

  Further, the valve body 40 is configured to be deformable so as to maintain the outer pressure and the pressure of the sealed space 50 equal. The outside pressure is a pressure outside the sealed space 50. That is, the pressure in a space (for example, a plant) in which the tank 1 is provided. The sealed space 50 is filled with air at normal temperature and pressure as described above. Therefore, when the pressure on the outside is higher than the pressure in the sealed space 50, the valve body 40 is deformed toward the sealed space 50. Thereby, the volume of the sealed space 50 is reduced, and the pressure of the sealed space 50 is increased. On the other hand, when the pressure on the outside is lower than the pressure in the sealed space 50, the valve body 40 is deformed to the outside of the sealed space 50. Thereby, the volume of the sealed space 50 is increased and the pressure of the sealed space 50 is reduced. Such deformation of the valve body 40 stops at a position where the pressure in the sealed space 50 becomes equal to the pressure outside the sealed space 50.

  In the present embodiment, the sealed space 50 is formed with a capacity having a heat insulating property capable of maintaining a temperature difference between the temperature outside the diaphragm 30 and the temperature outside the valve body 40. Thereby, since the sealed space 50 has a large air layer, the heat insulation effect can be enhanced. That is, even if there is a temperature difference between the temperature outside the diaphragm 30 and the temperature outside the valve body 40, it is difficult for the other temperature to be transmitted to the diaphragm 30 and the valve body 40 by the sealed space 50. It is possible to enhance the effect of preventing condensation.

  In the present embodiment, the valve body 40 is formed of a film having a surface area larger than the opening area of the opening 20A. That is, the valve body 40 is disposed in a state in which it is at least slack in the opening 20A. Such membranes should be light and thin. This is because the valve body 40 easily changes according to the pressure outside the sealed space 50.

  Furthermore, it is preferable that the valve body 40 is configured to be plastically deformable in accordance with the differential pressure between the outside pressure and the pressure in the sealed space 50. That is, it is preferable that the film constituting the valve body 40 is loose enough to be plastically deformed. With this configuration, the valve body 40 can be deformed with little resistance according to the pressure outside the sealed space 50.

  Such a valve body 40 is sandwiched and fixed between the tubular member 20 and the annular member 60. It is preferable that an O-ring 62 made of an elastic body is disposed between the tubular member 20 and the valve body 40, and the annular member 60 is disposed from the outside of the valve body 40. In this state, the valve body 40 and the cylindrical member are penetrated from the annular member 60 to the cylindrical member 20 and tightened with a plurality of bolts 61 (for example, four) provided in the annular circumferential direction. It becomes possible to fix while improving the adhesiveness with 20.

  Here, since the annular member 60 is configured in an annular shape, most of the valve body 40 is visible from the outside. Therefore, when it arrange | positions in the plant with which the tank 1 is provided as it is, there exists a concern about deterioration and damage of the valve body 40. FIG. Therefore, a lid member 70 is attached to the tubular member 20 so as to cover most of the valve body 40. The lid member 70 is screwed and fixed to the cylindrical member 20. The lid member 70 is provided with a through-hole 72 so that outside air can be introduced into a space 80 constituted by the tubular member 20, the valve body 40, the annular member 60, and the lid member 70.

  As a result, as shown in FIG. 3A, air in the space 80 can be discharged from the through hole 72 in accordance with the expansion of the sealed space 50, and the through hole according to the compression of the sealed space 50. It becomes possible to introduce the air in the space 80 from 72. As a result, the diaphragm 30 directly touches the liquid, but does not touch anything other than the air in the sealed space 50. For this reason, dew condensation of the diaphragm 30 can be prevented. Therefore, it is possible to detect the height of the liquid level in the tank 1 with high accuracy.

  In the pressure type level meter 10 having such a configuration, the displacement of the diaphragm 30 is transmitted to the signal processing unit 11. The signal processing unit 11 is disposed in the sealed space 50. The signal processing unit 11 outputs an electrical signal corresponding to the displacement of the diaphragm 30. This electrical signal may be a current signal or a voltage signal. Such an electrical signal is transmitted to an external device (not shown) via the signal line 12 that is liquid-tightly attached to the sealed space 50.

  As described above, according to the pressure type level meter 10 according to the present invention, the diaphragm 30 is sandwiched between the liquid in the tank 1 and the sealed space 50 and is not directly in contact with the outside air. For this reason, since the diaphragm 30 can be shielded from the outside air, even if there is a temperature difference between the liquid in the tank 1 and the outside air, the occurrence of condensation can be reliably prevented. Therefore, the height of the liquid level can be detected with high accuracy.

[Other Embodiments]
In the embodiment described above, the atmosphere is introduced into the sealed space 50. However, the scope of application of the present invention is not limited to this. It is also possible to fill the sealed space 50 with, for example, nitrogen gas so as to be at atmospheric pressure. As a result, moisture in the sealed space 50 can be completely removed, so that dew condensation on the diaphragm 30 can be reliably prevented.

  In the above embodiment, the valve body 40 has been described as being configured using a polyethylene film. However, the scope of application of the present invention is not limited to this. This film is suitable if it can be deformed with a light force and does not allow moisture to pass through while allowing air to pass through. It is also possible to use Japanese paper as the film. In addition, oil may be applied to a film (including Japanese paper) in order to improve waterproofness.

  In the above embodiment, the valve body 40 has been described as being configured to be plastically deformable in accordance with the differential pressure between the outside pressure and the pressure in the sealed space 50. However, the scope of application of the present invention is not limited to this. Of course, the valve body 40 may be configured using a material that does not undergo plastic deformation.

  In the above-described embodiment, the cylindrical member 20 has been described as having the opening area of the opening 20A wider than the opening area of the opening 20B. However, the scope of application of the present invention is not limited to this. Naturally, the cylindrical member 20 can be configured so that the opening area of the opening 20B is equal to the opening area of the opening 20A. Alternatively, the cylindrical member 20 can naturally be configured such that the opening area of the opening 20A is narrower than the opening area of the opening 20B.

  In the above embodiment, the valve body 40 has been described as being formed of a film having a surface area larger than the opening area of the opening 20A. However, the scope of application of the present invention is not limited to this. The valve body 40 can be formed of a film having a surface area equal to the opening area of the opening 20A, or can be formed of a film having a surface area narrower than the opening area of the opening 20A. .

  In the above embodiment, the valve body 40 has been described as being sandwiched and fixed by the tubular member 20 and the annular annular member 60. However, the scope of application of the present invention is not limited to this. For example, it is naturally possible to fix the valve body 40 without using the annular member 60.

  In the embodiment described above, the lid member 70 is attached to the cylindrical member 20. However, the scope of application of the present invention is not limited to this. The cover member 70 can be configured without being attached, or the cylindrical member 20 and the cover member 70 can be configured integrally.

  In the above embodiment, the valve body 40 has been described as being loosely disposed with respect to the opening 20A. However, the scope of application of the present invention is not limited to this. For example, as shown in FIG. 4, the valve body 40 may be configured in a bag shape. Even with such a configuration, the sealed space 50 can be configured, and condensation of the diaphragm 30 can be prevented.

  Further, as shown in FIG. 5, the tubular member 20 may be configured by arranging a valve body 40 that is fixed by an annular elastic member 91 and is loosened radially inward of the elastic member. Is possible.

  Further, as shown in FIG. 6, it is also possible to arrange a plate member 96 having a through hole 95 inside the cylindrical member 20 and attach a tube 97 to the through hole 95. By including the substance 99 (for example, oil) that is difficult to evaporate in the central portion of the tube 97, the sealed space 50 can be configured by the diaphragm 30 and the substance 99. In such a case, the substance 99 corresponds to the valve body 40 of the present invention. In such a configuration, the position of the substance 99 can be changed according to the pressure difference between the pressure in the sealed space 50 and the pressure in the space 80 (outside pressure). For this reason, it is possible to prevent the diaphragm 30 from touching the outside air while making the pressure of the sealed space 50 equal to the outside pressure. Therefore, even with such a configuration, the condensation of the diaphragm 30 can be reliably prevented. In addition, although not shown, it is possible to use a cylinder mechanism instead of the tube 97, for example.

  In the above embodiment, the cylindrical member 20 is illustrated in FIG. 1 such that the opening 20A and the opening 20B are configured coaxially. However, the scope of application of the present invention is not limited to this. Of course, it is also possible to form the cylindrical member 20 with the opening 20A and the opening 20B having different axes.

  In the above embodiment, the cylindrical member 20 has been described as being inserted with the opening 20 </ b> A protruding from the tank 1. However, the scope of application of the present invention is not limited to this. Naturally, the cylindrical member 20 can be provided in a state where the opening 20B side of the opening 20A is inserted into the tank 1 and the opening 20A is exposed to the outside of the tank 1.

  In the above embodiment, the cylindrical member 20 is illustrated as being cylindrical. However, the scope of application of the present invention is not limited to this. For example, it is naturally possible to form the tubular member 20 with a triangular column, a quadrangular column, or a polygonal column having more than that.

  In the above embodiment, the sealed space 50 is described as being formed with a capacity having a heat insulating property capable of maintaining a temperature difference between the temperature outside the diaphragm 30 and the temperature outside the valve body 40. . However, the scope of application of the present invention is not limited to this. For example, it is naturally possible to configure the capacitor with a heat insulating property such that the temperature outside the diaphragm 30 and the temperature outside the valve body 40 are difficult to communicate with each other.

  In the said embodiment, the pressure type level meter 10 demonstrated and demonstrated the example in case the tank 1 was applied. However, the scope of application of the present invention is not limited to this. That is, it is naturally possible to apply the pressure type level meter 10 to, for example, a pipe through which a liquid flows.

  In the above embodiment, the pressure type level meter 10 has been described as being disposed in the tank 1 with the opening 20A protruding. However, the scope of application of the present invention is not limited to this. For example, the present invention can also be applied to the case where the entire pressure type level meter 10 is put in the liquid in the tank 1 and only the outside air is taken in from the outside and measured. In such a case, an air pipe leading to the through hole 72 may be extended to the outside of the tank 1. Further, the opening 20 </ b> A may be disposed so as not to protrude from the wall surface of the tank 1. Even in such a case, it is naturally possible to measure the height of the liquid level and the like.

  INDUSTRIAL APPLICABILITY The present invention can be used in a pressure type level meter that measures the liquid pressure of a storage tank or a pipe that stores liquid and measures the height of the liquid level.

10: Pressure type level meter 20: Cylindrical member 20A: Opening (one opening)
20B: Opening (the other opening)
30: Diaphragm 40: Valve body 50: Sealed space 60: Annular member

Claims (5)

A cylindrical member that is formed into a cylindrical shape having openings at both ends, and outside air is introduced to the side of one opening;
A diaphragm that closes the other opening of the cylindrical member and deforms according to the hydraulic pressure;
A valve body that can be deformed so as to close the one opening and form a sealed space together with the diaphragm inside the cylindrical member, and to maintain an equal pressure outside and the pressure in the sealed space;
Pressure type level meter.   The pressure type level meter according to claim 1, wherein the valve body is formed of a film having a surface area larger than an opening area of the one opening.   The pressure type level meter according to claim 1 or 2, wherein the valve body is plastically deformable in accordance with a differential pressure between the outer pressure and the pressure in the sealed space.   The pressure type level meter according to any one of claims 1 to 3, wherein the cylindrical member is configured such that an opening area of the one opening is larger than an opening area of the other opening. The pressure type level meter according to any one of claims 1 to 4, wherein the sealed space is filled with air or nitrogen gas .

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