JP2008185388A - Fine differential pressure gage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fine differential pressure gage hardly influenced by a temperature change inside/outside an apparatus, capable adjusting a zero point more accurately with a simple structure, and resultantly measuring a fine differential pressure highly accurately. <P>SOLUTION: A channel is switched by operating at a prescribed timing, selector valves 21a, 22a provided on one side or on both sides of vent pipes 14, 15 connected to the first measuring chamber (high pressure side measuring chamber 11) and the second measuring chamber (low pressure side measuring chamber 12) partitioned across a diaphragm 13, and a pressure in the first measuring chamber (high pressure side measuring chamber 11) is equalized to a pressure in the second measuring chamber (low pressure side measuring chamber 12), to thereby adjust the zero point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fine differential pressure gauge that obtains a fine differential pressure by measuring a displacement amount of a diaphragm.

  Conventionally, various systems are known for monitoring and controlling the flow of fluid, and as one of them, a system having a diaphragm is widely used. The differential pressure gauge equipped with a diaphragm is used, for example, for environmental management of a clean room, hygiene management of a production line for foods and drugs, prevention of diffusion of bacteria and dust particles in hospitals and laboratories, and the like. Specifically, hygiene can be achieved by monitoring the environmental pressure of the clean room by monitoring the difference in the indoor pressure between the clean room and the adjacent room, or by maintaining the indoor pressure of the production line for food, drugs, etc. higher than the adjacent room. It is used for management and to prevent the spread of bacteria and dust particles by keeping the pressure in hospitals and laboratories lower than that in adjacent rooms.

  In the differential pressure gauge used for such applications, it is necessary to accurately grasp minute changes in pressure. Conventional differential pressure gauges often measure differential pressure in kPa units, so there was no problem in measurement even if the zero point shifted at the slight differential pressure level due to minute changes in pressure. Since the differential pressure gauge requires accuracy in Pa units, it is necessary to accurately adjust the zero point.

  However, the pressure in Pa is easily changed by a temperature change inside and outside the device. For this reason, as a method for making it less susceptible to the effects of temperature changes, for example, an invention is disclosed in which a temperature sensor is provided in a micro differential pressure gauge to detect the temperature, and temperature compensation of the differential pressure is performed with a temperature compensation calculator or the like. (For example, refer to Patent Document 1).

JP-A-6-58833 (paragraphs [0009] to [0010])

  However, the method of adjusting the zero point using a temperature sensor, a temperature compensation arithmetic unit, etc., for example, calculates the displacement amount of the diaphragm from information such as the outside air temperature obtained by the sensor, the actually measured value, Since the numerical value obtained as a result of calculation in consideration of the amount of displacement is used as the measurement value, the accuracy is lacking. That is, a pressure lower than a predetermined numerical value must be ignored, and there is a limit to the precision of measurement other than using the approximate value as a measured value. In addition, since devices such as sensors and calculators are used, there is a possibility that errors due to device malfunctions or calculation errors may occur.

  The present invention has been made in view of such a point, and the object thereof is to be less susceptible to temperature changes inside and outside the device, and with a simple structure, the zero point can be adjusted more accurately, and as a result An object of the present invention is to provide a micro differential pressure gauge capable of performing high micro differential pressure measurement.

  (1) A first measurement chamber and a second measurement chamber, which are partitioned with a diaphragm interposed therebetween and are connected to a vent pipe connected to the outside, respectively, and the amount of displacement of the diaphragm is measured to obtain a fine differential pressure. A differential pressure gauge, wherein at least one of the vent pipes is provided with a switching valve for switching a flow path so as to eliminate a differential pressure between the first measurement chamber and the second measurement chamber. Fine differential pressure gauge.

  According to the present invention, the first measurement chamber and the second measurement chamber partitioned by sandwiching the diaphragm are connected to the vent pipes that are connected to the outside (the target area for measuring the minute differential pressure), and at least one of the vent pipes. In addition, since the switching valve for switching the flow path so as to eliminate the differential pressure between the first measurement chamber and the second measurement chamber is provided, a highly accurate fine differential pressure measurement is performed with a simple structure. be able to.

  That is, the switching valve provided in one or both of the ventilation pipes connected to the first measurement chamber and the second measurement chamber operates at a predetermined timing to switch the flow path. By making the pressure in the measurement chamber equal to the pressure in the second measurement chamber, the displacement amount of the diaphragm becomes zero, and the zero point is adjusted.

  Zero point adjustment is performed by mechanically switching the flow path, and there is no need for complicated mechanisms such as temperature sensors and calculators. Thus, the zero point adjustment can be performed more accurately, and as a result, a highly accurate differential pressure measurement can be performed.

  (2) The fine differential pressure gauge according to (1), wherein the vent pipe is opened to an atmospheric pressure by switching the switching valve.

  According to the present invention, since the ventilation pipe is opened to the atmospheric pressure by switching the switching valve, both the first measurement chamber and the second measurement chamber are opened to the atmospheric pressure, and the first measurement is performed. Since both the pressure in the room and the pressure in the second measurement room are equal to the atmospheric pressure, the displacement amount of the diaphragm becomes zero, and the zero point is adjusted.

  By opening the vent pipe to the atmospheric pressure at a predetermined timing, it is possible to perform zero point adjustment more accurately with a simple structure, and thus to perform highly accurate differential pressure measurement.

  (3) The differential pressure gauge according to (1), wherein the first measurement chamber and the second measurement chamber are communicated with each other by the vent pipe by switching the switching valve.

  According to the present invention, since the first measurement chamber and the second measurement chamber are communicated with each other by the ventilation pipe by switching the switching valve, the fluid in the first measurement chamber and the second measurement chamber are connected to each other. Fluid can be circulated through the vent pipe. When the pressures in the first measurement chamber, the vent pipe, and the second measurement chamber are all equal, the displacement of the diaphragm becomes zero, and the zero point is adjusted.

  By connecting the first measurement chamber and the second measurement chamber at a predetermined timing, the zero point can be adjusted more accurately with a simple structure, and consequently, a highly accurate differential pressure measurement is performed. be able to.

  In addition, since the fluid in the apparatus flows through the closed system only in the first measurement chamber, the second measurement chamber, and the vent pipe, the fluid does not flow out of the apparatus. Even when handling fluids such as, it is possible to safely measure.

  (4) The fine differential pressure gauge according to (3), wherein the fine differential pressure gauge further includes a sealed box, and the switching valve is provided in the box.

  According to the present invention, since the switching valve is provided in a sealed box provided in the micro differential pressure gauge, fluid may flow out of the switching valve for some reason when the switching valve is operated. Even in such a case, the fluid that has flowed out stays in a sealed box, and leakage of the fluid to the outside of the apparatus can be prevented, so that it is possible to perform finer differential pressure measurement with higher safety.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 are schematic cross-sectional views showing the internal structure of the fine differential pressure gauge according to the embodiment of the present invention, and in particular, the structure of the differential pressure measuring unit 10 and the vent pipes 14 and 15. Here, FIG. 1 shows the internal structure during differential pressure measurement, and FIG. 2 shows the internal structure during zero point adjustment.

  1 and 2, the fine differential pressure gauge according to the embodiment of the present invention includes a differential pressure measurement unit 10 including a high pressure side measurement chamber 11, a low pressure side measurement chamber 12, and a diaphragm 13, and includes a high pressure side. A measurement chamber (first measurement chamber) 11 and a low-pressure side measurement chamber (second measurement chamber) 12 are partitioned with a diaphragm 13 interposed therebetween. The high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12 are connected to the vent pipes 14 and 15 connected to the outside, respectively, and serve as a flow path for circulating an external fluid and a fluid in each measurement chamber. Yes.

  At the time of measuring the differential pressure, the switching valve 21a of the flow path switching unit 21 provided in the vent pipe 14 is operated to shut off the atmospheric pressure, and the high pressure side measurement chamber 11 is communicated with the outside. A high-pressure fluid flows in the side measurement chamber 11. At the same time, the switching valve 22a of the flow path switching unit 22 provided in the ventilation pipe 15 is operated to shut off the atmospheric pressure, and the low pressure side measurement chamber 12 is communicated with the outside. A low-pressure fluid flows through 12 (see FIG. 1). Due to the pressure difference between the high-pressure fluid flowing in the high-pressure side measurement chamber 11 and the low-pressure fluid flowing in the low-pressure side measurement chamber 12, it is provided between the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12. The diaphragm 13 is displaced, and a minute differential pressure is obtained by measuring the displacement amount.

  When the zero point is adjusted, the switching valves 21a and 22a of the flow path switching units 21 and 22 are operated to switch the flow path, and the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12 are shut off from the outside and The trachea 14 and 15 are each opened to atmospheric pressure (see FIG. 2). The pressures in the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12 are both equal to the atmospheric pressure, and the pressure difference between the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12 is eliminated, so that the displacement of the diaphragm 13 is reduced. It becomes zero and the zero point is adjusted accurately.

  In the micro differential pressure gauge according to the embodiment of the present invention, by providing a timer (not shown), the flow path is switched at regular time intervals to perform zero point adjustment. Since the time required for the zero point adjustment is very short (for example, 1 second or less), the zero point adjustment is performed while maintaining the measurement value immediately before the flow path switching, and the measurement is resumed after the operation is completed. The differential pressure can be measured.

  3 and 4 are schematic cross-sectional views showing the internal structure of a micro differential pressure gauge according to another embodiment of the present invention, in particular, the structures of the differential pressure measuring unit 10 and the vent pipes 14 and 15. Yes. FIG. 3 shows the internal structure during differential pressure measurement, and FIG. 4 shows the internal structure during zero point adjustment.

  3 and 4, the flow path switching units 21 and 22 provided in the vent pipes 14 and 15 are for switching valves 21a and 22a for opening to atmospheric pressure, and for blocking the flow of fluid from the outside. It consists of two types of switching valves, switching valves 21b and 22b.

  At the time of differential pressure measurement, the switching valve 21a of the flow path switching unit 21 provided in the vent pipe 14 operates to shut off the atmospheric pressure, the switching valve 21b operates to connect the high-pressure side measurement chamber 11 to the outside, and A high-pressure fluid flows through the trachea 14 into the high-pressure side measurement chamber 11. At the same time, the switching valve 22a of the flow path switching unit 22 provided in the ventilation pipe 15 is operated, the atmospheric pressure is shut off, the switching valve 22b is operated, and the low-pressure side measurement chamber 12 is communicated with the outside. Then, a low-pressure fluid flows in the low-pressure side measurement chamber 12 (see FIG. 3).

  Further, at the time of zero point adjustment, the flow path switching units 21 and 22 switch the flow path, the switching valves 21b and 22b are operated, and the high pressure side measurement chamber 11 and the low pressure side measurement chamber 12 are shut off from the outside. The valves 21a and 22a operate to open the vent pipes 14 and 15 to atmospheric pressure (see FIG. 4).

  By using two types of switching valves provided in the vent pipes 14 and 15, it is possible to reduce the load applied to the flow path switching units 21 and 22 during zero point adjustment, and to increase the safety of the apparatus. That is, in the differential pressure gauge shown in FIG. 2, the flow of the fluid from the outside is blocked only by the switching valves 21a and 22a at the time of zero point adjustment, so the pressure of the external fluid is limited to one point of the switching valves 21a and 22a. In particular, a large load is applied to the switching valve 21a on the high pressure side. By providing two types of switching valves, one (21a, 22a) opens the vent pipe to atmospheric pressure, and the other (21b, 22b) shuts off the flow of fluid from the outside, so that the load on the switching valve is reduced. It is reduced. Further, by providing the connecting pipe 16 provided with a partition 25 in the center at the position of the switching valves 21b and 22b (see FIG. 4), the pressure applied to the switching valve is distributed to the connecting pipe 16 and the partition 25, and the switching valve The load applied to 21b and 22b can be further reduced.

  5 and 6 are schematic cross-sectional views showing the internal structure of the fine differential pressure gauge used for measuring the differential pressure of the combustion system gas, and in particular, the structures of the differential pressure measuring unit 10 and the vent pipes 14 and 15. . FIG. 5 shows the internal structure during differential pressure measurement, and FIG. 6 shows the internal structure during zero point adjustment.

  5 and 6, a communication pipe 17 is connected between the high-pressure side vent pipe 14 and the low-pressure side vent pipe 15, and a flow path switching unit 23 provided in the high-pressure side vent pipe 14. The flow path is switched.

  At the time of measuring the differential pressure, the switching valve 23a of the flow path switching unit 23 provided in the vent pipe 14 is operated, the high pressure side measurement chamber 11 is communicated with the outside, and the high pressure side measurement chamber 11 passes through the vent pipe 14 and has a high pressure. Fluid flows. The low-pressure side measurement chamber 12 is communicated with the outside by a vent pipe 15, and low-pressure fluid flows through the vent pipe 15 into the low-pressure side measurement chamber 12 (see FIG. 5). Due to the pressure difference between the high-pressure fluid flowing in the high-pressure side measurement chamber 11 and the low-pressure fluid flowing in the low-pressure side measurement chamber 12, it is provided between the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12. The diaphragm 13 is displaced, and a minute differential pressure is obtained by measuring the displacement amount.

  Further, at the time of zero point adjustment, the switching valve 23a of the flow path switching unit 23 is operated to switch the flow path, the high pressure side measurement chamber 11 is shut off from the outside, and the high pressure side vent pipe 14 and the low pressure side passage are connected. The trachea 15 communicates with the communication pipe 17 (see FIG. 6). Therefore, the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12 are communicated with each other through the vent pipes 14 and 15 and the communication pipe 17. A low-pressure fluid flows through the pipe 17 and the high-pressure side vent pipe 14. As a result, since the low-pressure fluid flows through both the high-pressure side measurement chamber 11 and the low-pressure side measurement chamber 12, the displacement of the diaphragm 13 becomes zero, and the zero point is adjusted accurately.

  According to the differential pressure gauge according to the present embodiment, the fluid in the apparatus flows only in the high-pressure side measurement chamber 11, the low-pressure side measurement chamber 12, the vent pipes 14 and 15, and the communication pipe 17, so that the fluid Even when a fluid such as a combustion system gas is measured without flowing out of the apparatus, it is possible to perform highly safe differential pressure measurement.

  FIG. 7 and FIG. 8 are schematic cross-sectional views showing the internal structure of a fine differential pressure gauge that is a fine differential pressure gauge used for measuring the differential pressure of a combustion system gas, and particularly equipped with a system for preventing gas leakage. . FIG. 7 shows the internal structure during differential pressure measurement, and FIG. 8 shows the internal structure during zero point adjustment.

  7 and 8, a sealed box 30 is provided around the flow path switching unit 23. When the switching valve 23a is operated, fluid flows out of the switching valve 23a for some reason. Even if this occurs, the fluid that has flowed out stays in the sealed box 30, so that leakage of the fluid to the outside of the apparatus can be prevented more reliably. Therefore, even when a fluid such as a combustion system gas is measured, it is possible to perform a safer differential pressure measurement.

  The fine differential pressure gauge according to the present invention is less susceptible to temperature changes inside and outside the device, can adjust the zero point more accurately with a simple structure, and can therefore perform highly accurate differential pressure measurement. Useful.

It is a schematic cross section which shows the internal structure at the time of the differential pressure measurement of the micro differential pressure gauge which concerns on embodiment of this invention. It is a schematic cross section which shows the internal structure at the time of the zero point adjustment of the micro differential pressure gauge which concerns on embodiment of this invention. It is a schematic cross section which shows the internal structure at the time of the differential pressure measurement of the micro differential pressure gauge which concerns on other embodiment of this invention. It is a schematic cross section which shows the internal structure at the time of the zero point adjustment of the micro differential pressure gauge which concerns on other embodiment of this invention. It is a schematic cross section which shows the internal structure at the time of the differential pressure measurement of the micro differential pressure gauge used for the differential pressure measurement of combustion type | system | group gas. It is a schematic cross section which shows the internal structure at the time of zero point adjustment of the fine differential pressure gauge used for the differential pressure measurement of combustion type | system | group gas. It is a schematic cross section which shows the internal structure at the time of the differential pressure measurement of the micro differential pressure gauge used for the differential pressure measurement of combustion type | system | group gas. It is a schematic cross section which shows the internal structure at the time of the zero point adjustment of the fine differential pressure gauge used for the differential pressure measurement of combustion type | system | group gas.

Explanation of symbols

10 Differential pressure measurement unit
DESCRIPTION OF SYMBOLS 11 High pressure side measurement chamber 12 Low pressure side measurement chamber 13 Diaphragm 14,15 Ventilation pipe 16 Connection pipe 17 Communication pipe 21,22,23 Flow path switching part 25 Partition part 30 Sealing box

Claims (4)

A fine differential pressure gauge that includes a first measurement chamber and a second measurement chamber that are partitioned by a diaphragm and each connected to a vent pipe that is connected to the outside, and that measures the displacement of the diaphragm to obtain a fine differential pressure. There,
A fine differential pressure gauge comprising a switching valve for switching a flow path so as to eliminate a differential pressure between the first measurement chamber and the second measurement chamber in at least one of the vent pipes.   The fine differential pressure gauge according to claim 1, wherein the vent pipe is opened to atmospheric pressure by switching the switching valve.   The fine differential pressure gauge according to claim 1, wherein the first measurement chamber and the second measurement chamber are communicated by the vent pipe by switching the switching valve. The fine differential pressure gauge further includes a sealed box,
The differential pressure gauge according to claim 3, wherein the switching valve is provided in the box.

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