JP2005257551A - Flowrate sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flowrate sensor capable of precisely detecting a flow rate, in which product management is facilitated, while reducing restrictions of installation. <P>SOLUTION: The constitution is adopted, in which the primary pressure and the secondary pressure in front and behind an orifice 3 of a piping part 1 are introduced into a pair of pressure rooms 12a and 12b formed on both sides of a diaphragm 10, in which the displacement of the diaphragm 10, caused by the differential pressure between both the pressures, is detected, using a magnetic body 27 and a magnetic detection element 28; and in which the displacement is transformed into an electric signal, regarding the flow rate by calculation so as to be output. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flow sensor used to detect a flow rate.

  In a system in which a fluid such as water is often circulated, a flow meter, and in many cases, a bypass type flow meter is used to measure the flow rate of the fluid flowing in the pipe.

  As shown in FIG. 2, the bypass type flow meter uses a pipe portion b provided with an orifice a, and is movably accommodated in a taper tube c using a differential pressure before and after the orifice a. A structure for displacing the float d is used.

  In many cases, as shown in FIG. 2, the fluid to be measured that flows in the piping part b from the front and back (primary side, secondary side) of the orifice a passes through the relay passages e and f, and the tapered pipe c In other words, a correction orifice g is provided on the primary taper tube end side. Then, due to the differential pressure before and after the orifice a, the behavior is such that the primary fluid with high pressure (orifice upstream) flows from the correction orifice g to the secondary with low pressure (downstream of the orifice) through the tapered tube c. Is used to measure the flow rate. Specifically, the flow rate is measured by visually recognizing the float position in the taper tube c from the outside.

  However, the bypass type flow meter has a structure that measures the flow rate by visually recognizing the float position, so it must be installed in consideration of visibility, and there is a problem that the installation is considerably restricted. In addition, since the flow meter depends on parts such as the tapered tube c and the correction orifice g, the change of the measurement target fluid and the change of the specification of the measurement flow rate are required by preparing various kinds of parts in advance. The product management is quite troublesome. Moreover, the cost of maintaining the management is also a considerable burden. In addition, the measurement accuracy is likely to vary due to many parts changes.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a flow rate sensor that can easily manage products and can detect a flow rate with high accuracy while suppressing installation restrictions.

  In order to achieve the above-mentioned object, the invention according to claim 1 leads the primary pressure and the secondary pressure before and after the orifice of the piping section to a pair of pressure chambers formed on both sides of the diaphragm, and the difference between the two pressures. A configuration was adopted in which the displacement of the diaphragm caused by pressure was detected and the displacement was output as an electrical signal related to the flow rate.

  The invention according to claim 2 further employs a configuration in which the output unit includes a detection unit having a magnetic body that displaces following the diaphragm and a magnetic detection element that detects the displacement of the magnetic body.

  The invention described in claim 3 is such that the output portion has a maximum sensitivity for detecting the displacement of the diaphragm when the flow rate is zero.

  The invention described in claim 4 employs a configuration in which the output unit further includes a calculation unit for obtaining a flow rate in accordance with the displacement of the diaphragm.

  In the invention described in claim 5, a signal capable of digitally displaying the flow rate is further output from the output unit.

  According to the first aspect of the present invention, since only the measurement part is separated from the visual recognition part and is installed at a place where measurement is necessary, the measurement part is installed without being restricted by installation. it can. Moreover, since the diaphragm displacement is converted into an electrical signal related to the flow rate, it is possible to easily cope with changes in the specifications of the fluid to be measured and the measured flow rate. In addition, since many parts can be shared, the cost required to maintain product management can be reduced. In addition, it is easy to ensure accuracy, and detection accuracy can be improved.

  According to the second aspect of the present invention, in addition to the above effect, there is an effect that the displacement of the diaphragm can be detected with a simple structure using a magnetic body and a magnetic detection element.

  According to the third aspect of the present invention, in addition to the above effect, when the differential pressure is small and the flow rate is small, the output unit is in a state where it is easy to detect a minute displacement of the diaphragm, so that it is difficult to detect the differential pressure. There is an effect that high detection accuracy can be secured even at a small flow rate.

  According to the fourth aspect of the present invention, in addition to the above effect, there is an effect that the flow rate can be easily detected by utilizing the relationship between the differential pressure and the flow rate.

  According to the invention described in claim 5, in addition to the above effect, there is an effect that the detected flow rate can be visually recognized on a digital display at a point far from the flow rate sensor.

[One Embodiment]
Hereinafter, the present invention will be described based on an embodiment shown in FIG.

  FIG. 1 shows a cross-sectional view of the flow rate sensor, in which 1 is a cylindrical main pipe (corresponding to the pipe part of the present application). The main pipe 1 has internal thread portions 2 on the inner surface as connecting portions at both ends. And, as shown by the two-dot chain line in FIG. 1, the main pipe 1 is attached to the pipe path X for measuring the flow rate in the fluid system using the female thread portion 2. An orifice 3 is attached in the middle of the flow path 1a formed in the main pipe 1, for example, at the center. A pair of pressure introducing holes 5 formed by small holes are formed on the wall surface portion of the flow path 1a before and after the orifice 3 so that the pressure before and after the orifice can be taken out from the pressure introducing hole 5. ing.

  From the center of the side part of the main pipe 1, for example, a flange-like pedestal 6 protrudes. For example, two layers of main body blocks 7 and 8 are attached to the base 6. Concave portions 9a and 9b are formed on the upper and lower surface portions where the main body blocks 7 and 8 overlap so as to face each other. A diaphragm 10 is attached between the main body blocks 7 and 8 so as to block the recesses 9a and 9b, and a pair of pressure chambers 12a and 12b separated by the diaphragm 10 are formed on both sides of the diaphragm 10. doing. These pressure chambers 12 a and 12 b communicate with the pair of pressure introduction holes 5 through a pair of pressure introduction passages 13 a and 13 b formed in each part of the main body blocks 7 and 8. As a result, the pressure generated before and after the orifice, that is, the primary pressure that is upstream of the orifice 3 is introduced into the pressure chamber 12b, and the secondary pressure that is downstream of the orifice 3 is introduced into the pressure chamber 12a. The structure is introduced.

  A take-out member 15 for taking out the displacement of the diaphragm 10 is attached to the center of the diaphragm 10. The take-out member 15 has a fixed portion 15a attached to the central diaphragm portion (the pressure chamber 12a side) of the diaphragm 10, and a diaphragm rod portion 15b protruding from the fixed portion 15a to the pressure chamber 12a on the secondary side. Configured. The diaphragm rod portion 15b is slidably guided in a guide hole 16 formed in the main body block 7 immediately above the secondary pressure chamber 12a. With this guide, the displacement of the diaphragm 10 caused by the differential pressure between the primary side pressure and the secondary side pressure applied to the pair of pressure chambers 12a and 12b is converted into the reciprocating movement (displacement) of the diaphragm rod portion 15b. I have to.

  The diaphragm 10 is urged toward the pressure chamber 12b by the urging mechanism 18 so that the diaphragm 10 operates in accordance with the differential pressure. That is, the urging mechanism 18 has a structure using a spring receiving member 19 connected to the end of the diaphragm rod portion 15 and a cover member 22 attached to the upper surface of the main body block 7. Specifically, the spring receiving member 19 includes a shaft portion 20a that fits in the end portion of the diaphragm rod portion 15b in the guide hole 16, and a spring seat that is disposed outside the main body block 7 following the shaft portion 20a. 20b. The cover member 22 has a bottomed cylindrical portion 22 a that surrounds the spring receiving member 19. Between the spring seat 20b and the inner bottom surface of the cylindrical portion 22a facing the spring seat 20b, a spring member, here two types of coil springs 23a and 23b, are interposed in a compressed state, and the coil spring 23a. , 23b urges the take-out member 15 to press the central portion of the diaphragm 10 against the bottom surface of the recess 9b (pressure chamber 12b). Due to this urging, when the flow rate is zero, the diaphragm 10 is not displaced, and as the flow rate increases and the differential pressure between the pressure chambers 12a and 12b increases, the diaphragm 10 moves away from the bottom surface of the recess 9b. Is given.

  An output unit 25 is provided around the urging mechanism 18. The output unit 25 has a structure including a detection unit 26 that detects the displacement of the diaphragm 10 and a calculation unit 30 that converts the displacement of the diaphragm 10 into a signal related to the flow rate.

  In the detection unit 26, for example, a magnetic body 27 (for example, a permanent magnet) is installed on the upper surface portion of the spring seat 20b that becomes a dead space surrounded by the coil springs 23a and 23b, and outside the peripheral wall of the cylindrical portion 22a, A structure in which a magnetic detection element 28 for detecting the magnetism of the magnetic body 27 is provided is used. That is, the detection unit 26 has a structure in which the displacement amount of the diaphragm 10 is detected by detecting the magnetic change of the magnetic body 27 that is displaced following the diaphragm 10 by the magnetic detection element 28. As shown in FIG. 1, the magnetic body 17 and the magnetic detection element 28 are arranged in a positional relationship in which they are closest when the flow rate is zero. Thereby, the sensitivity for detecting the displacement of the diaphragm 10 of the detection unit 26 is set to be maximum when the flow rate is zero. This setting makes it easy to detect a slight displacement of the diaphragm 10 whose differential pressure is near zero.

  The calculating part 30 is comprised from the circuit board 31 arrange | positioned, for example on the upper side of the cylindrical part 22a. For example, the circuit board 31 is supported by a plurality of bosses 32 protruding from the upper surface of the main body block 7. Various semiconductor components 33 and electronic components (not shown) are mounted on the circuit board 31. A magnetic detection element 28 is connected to the circuit board 31. The circuit board 31 is formed with an arithmetic circuit for obtaining a flow rate having linear characteristics. Specifically, since the square root of the differential pressure before and after the orifice is known to be proportional to the flow rate, using this, the circuit board 31 has the square root of the displacement amount of the diaphragm 10 converted from the differential pressure. An arithmetic circuit that calculates and obtains a flow rate having a linear characteristic based on the arithmetic is set. Thereby, based on the displacement of the diaphragm 10, the flow rate of the fluid flowing through the main pipe 1 is detected.

  The circuit board 31 is set with a function for outputting the obtained flow rate from the external output terminal portion 31a as a signal (digital signal) that can be digitally displayed. A signal output from the external output terminal portion 31a (electrical signal related to the flow rate) allows the flow rate to be detected from a display unit installed at a point away from the flow rate sensor, such as a digital display unit 34a formed on the control panel 34. Display is done. FIG. 1 shows an example in which the control panel 34 is connected to the external output end 31 a via a signal line 35.

  In FIG. 1, reference numeral 36 denotes a cover for shielding the upper body block 7 and the circuit board 31, 37 denotes a screw member for fixing each part of the component, and 38 fastens the body blocks 7 and 8 to the base 6. The bolt member is shown.

  Next, the operation of the flow sensor configured as described above will be described.

  Assume that a flow rate sensor is attached to the piping path X as shown in FIG. 1 and the flow rate flowing through the piping path X is detected. At this time, a differential pressure is generated before and after the orifice in accordance with the flow rate of the fluid passing through the orifice 3.

  At this time, the primary pressure before the orifice is introduced into the primary pressure chamber 12b through the pressure introduction hole 5 (before the orifice) and the pressure introduction path 13a. The secondary pressure after the orifice is introduced into the secondary pressure chamber 12a through the pressure introduction hole 5 (after the orifice) and the pressure introduction path 13b.

  Here, since the differential pressure before and after the orifice (primary side pressure−secondary side pressure) increases as the flow rate through the orifice 3 increases, the diaphragm 10 is indicated by a two-dot chain line in FIG. 1. In this way, the pressure chamber 23b is displaced away from the inner bottom surface by an amount corresponding to the differential pressure. Thereby, the differential pressure generated before and after the orifice is converted into the displacement of the diaphragm 10. Then, the position of the magnetic body 27 changes (displaces) in accordance with the displacement of the diaphragm 10.

  On the other hand, the magnetic detection element 28 arranged at a fixed position detects a change in magnetism due to the movement of the magnetic body 27. By detecting this magnetism, the amount of displacement of the diaphragm 10 which is a differential pressure is detected. Then, the displacement information is input to the circuit board 31, and from the arithmetic circuit built on the circuit board 31, using the arithmetic expression that the square root of the differential pressure is proportional to the flow rate, the main pipe 1, that is, the piping path The flow rate of the fluid flowing through X is detected.

  The information about the flow rate is an electrical digital signal, and is installed at the control panel 34 at a point away from the point where the flow rate sensor is installed from the external output terminal portion 31a, that is, at a point with excellent visibility. It is output to the control panel 34.

  Thereby, if there is a request for flow rate display from the control panel 34, the flow rate of the fluid flowing through the piping path X is digitally displayed on the digital display unit 34a.

  In this way, unlike the bypass flow meter, the differential pressure type flow rate sensor is separated from the visible portion for visually checking the flow rate and is installed at the location necessary for the measurement on the piping path X, unlike the bypass type flow meter. Therefore, it is possible to avoid the restriction caused by the requirement of visibility like a bypass type flow meter. Moreover, since the change in the diaphragm 10 is detected and converted into a signal related to the flow rate, even if the fluid to be measured is changed or the specification of the measured flow rate is changed, the output unit 2 is changed, particularly the calculation unit 30 is set. You can easily deal with changes by simply changing In addition, many components of the differential pressure type flow sensor can be shared even if the fluid to be measured is changed or the specification of the measurement flow rate is changed, so that product management can be easily maintained and the necessary cost can be reduced. In addition, by sharing parts, variation in accuracy among products can be suppressed, so that accuracy can be easily secured and detection accuracy can be improved.

  In particular, since the structure using the magnetic body 27 and the magnetic detection element 28 is adopted for detecting the displacement of the diaphragm 10, the displacement of the diaphragm 10 can be easily detected. Moreover, since the detection is set so that the detection sensitivity is maximized when the flow rate is zero, the small displacement of the diaphragm 10 caused by the differential pressure near zero is easy to detect, and the differential pressure is difficult to detect. Even at a flow rate, the flow rate can be detected with high accuracy. In addition, the flow rate can be easily obtained because the flow rate is detected from the displacement of the diaphragm 10 using the relationship between the differential pressure and the flow rate. In addition, since the output flow rate is output as a digital signal that can be digitally displayed, the detected flow rate can be displayed in a place with good visibility regardless of the location where the flow rate sensor is installed.

  The present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention.

Sectional drawing which shows the differential pressure type flow sensor which concerns on one Embodiment of this invention. Sectional drawing which shows the conventional flowmeter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Main piping (pipe part), 1a ... Flow path, 3 ... Orifice, 5 ... Pressure introduction hole, 10 ... Diaphragm, 12a, 12b ... Pressure chamber, 13a, 13b ... Pressure introduction path, 25 ... Output part, 26 ... Detection unit, 30... Operation unit, 27 .. magnetic body, 28... Magnetic detection element, 31.

Claims (5)

A flow path through which a fluid flows, and a piping section with an orifice interposed in the middle of the flow path;
A pair of pressure chambers formed on both sides of the diaphragm separated by a diaphragm;
A pair of pressure introduction passages for guiding a primary pressure and a secondary pressure generated before and after the orifice to the pair of pressure chambers;
A flow rate sensor comprising: an output unit that detects a displacement of the diaphragm caused by a differential pressure in the pair of pressure chambers and outputs the displacement as an electrical signal related to the flow rate.   The flow rate sensor according to claim 1, wherein the output unit includes a detection unit having a magnetic body that is displaced following the diaphragm and a magnetic detection element that detects the displacement of the magnetic body. .   3. The flow sensor according to claim 1, wherein the output unit is configured such that sensitivity of detecting a displacement of the diaphragm is maximized when the flow rate is zero. 4.   The flow rate sensor according to any one of claims 1 to 3, wherein the output unit includes a calculation unit that calculates a flow rate according to displacement of the diaphragm.   The flow rate sensor according to any one of claims 1 to 4, wherein a signal capable of digitally displaying a flow rate is output from the output unit.

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