JPH08128872A - Differential pressure type flowmeter - Google Patents

Abstract

PURPOSE: To reduce the driving force of the variable throttle valve of a variable throttle type differential pressure gauge without deteriorating the high seal property of the valve. CONSTITUTION: A differential pressure type flowmeter is provided with a variable throttle valve 8 which controls the flow rate of a fluid in a flow rate measuring pipe 6, a driving section 12 which drives the valve 8, a position sensor 18 which detects the position of the valve 8, pressure sensor 33 which measures the differential pressure across the valve 8, and flow rate calculating section 21 which calculates the flow rate of the fluid by using the signals of the sensors 18 and 33. The driving force of the driving section 12 is reduced by partitioning the inside and outside of the pipe 6 in which the valve 8 is moved with a magnetic fluid seal 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter for measuring a flow rate by a differential pressure.

[0002]

2. Description of the Related Art When measuring a flow rate by a differential pressure, it is known to use a variable throttle to widen the measuring range. A conventional one of this type will be described with reference to, for example, JP-A-64-53119.

In FIG. 11, 1 is a pipe line, 2 is a variable diaphragm, and 3 is its rotation axis. Numerals 4 and 5 are pressure outlets.

In the above structure, the shaft 3 is used when the flow rate is high.
Around the center of the throttle valve 2 so that the gaps a1, a2 of the throttle valve 2 become large, and when the gaps a1, a2 are small, the gaps a1, a2 become smaller, and the pressure outlets 4 and 5 provided before and after the throttle valve 2 The flow rate was calculated based on the differential pressure of.

[0005]

However, when a member such as the throttle valve 2 is arranged in the flow path 1 as in the above example and it is driven from the outside, the sealing structure of that portion is Was needed. For the sealing of such a part, a sealing method using a solid material such as push is generally used, but in that case, if an attempt is made to improve the sealing performance, a large driving force is required to overcome the frictional force. It had a problem of becoming. The present invention solves the above problems, and an object of the present invention is to reduce the driving force of a throttle valve while maintaining high sealing performance in a differential pressure type flow meter using a variable throttle valve.

[0006]

In order to achieve the above object, the present invention provides a variable throttle valve for adjusting the flow rate in a flow rate measuring pipe, a drive unit for the valve, a position sensor for the valve, and a valve for the valve. The measurement in which the pressure sensor for measuring the differential pressure between the front and rear and the flow rate calculation unit for calculating the flow rate using the signal from the position sensor and the signal from the pressure sensor are provided, and the valve body of the variable throttle valve moves. A magnetic fluid seal portion is provided on the partition inside and outside the tube.

Further, the magnetic fluid seal portion is composed of a multi-stage seal portion. Also, a variable throttle valve that adjusts the flow rate in the flow rate measuring pipe, a drive unit of the valve, a position sensor of the valve, a pressure sensor that measures a differential pressure across the valve, and a signal from the position sensor. A flow rate calculation unit that calculates a flow rate using a signal from a pressure sensor, and a first magnetic fluid seal unit is provided in a partition inside and outside the measurement pipe in which the valve body of the variable throttle valve moves, The second magnetic fluid seal portion is provided in the lower portion.

A variable throttle valve for adjusting the flow rate in the flow rate measuring pipe, a drive unit for the valve, a position sensor for the valve,
The variable throttle valve includes a pressure sensor that measures a differential pressure across the valve, and a flow rate calculation unit that calculates a flow rate using a signal from the position sensor and a signal from the pressure sensor. A first magnetic fluid seal part is provided on the partition inside and outside the measurement pipe, a second magnetic fluid seal part is provided on the lower part inside the measurement pipe, and a third magnetic fluid seal part is provided on the side part of the measurement pipe. It has a different structure.

[0009]

According to the present invention, when the variable throttle valve is driven according to the magnitude of the measured flow rate, the seal of the moving portion of the valve is constituted by the magnetic fluid seal portion so that the valve can be opened with a small driving force. The degree can be adjusted.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a variable throttle valve 8 made of a magnetic material is arranged on an upper wall 7 of a flow rate measuring pipe 6 having a rectangular cross section. The tip portion 8a of the variable throttle valve 8 is formed in an edge shape, and the side portion 8b is formed in a flat plate shape. The variable throttle valve 8 is mounted on the rack 9 and is connected to the motor 10
It is configured to be driven by the pinion 12 attached to the shaft 11 of the. The motor 10, the rack 9, and the pinion 12 constitute a drive unit 13 of the variable throttle valve 8 as a whole. The motor 10 is fixed to a support plate 14 attached to the upper wall 7.

FIG. 2 shows a cross section taken along the line AA 'of FIG. A holder 1 for holding the rack 9 on the support plate 14.
5, the holding portion 16 of the holder 15 fits in the groove 17 of the rack 9 and holds the rack 9 so that it can be moved smoothly.

Further, a support portion 19 having a position sensor 18 arranged at the tip thereof is attached to the support plate 14, and a distance k from the reflection plate 20 attached to the upper part of the variable throttle valve 8 is set.
The opening degree h (-k) of the variable throttle valve 8 is detected by measuring. The signal from the position sensor 18 is sent to the flow rate calculation unit 21.

In FIG. 1, a magnetic fluid seal portion 22 is formed on the upper wall 7 of the flow rate measuring pipe 6. The magnetic fluid seal portion 22 is a permanent magnet 23 magnetized vertically in FIG.
And pole pieces 24 and 25 arranged above and below the variable throttle valve 8 formed of a magnetic material, and the pole piece 2.
The magnetic fluid 2 arranged between the variable throttle valve 8 and the variable throttle valve 8
It is composed of 6, 27.

FIG. 3 is a sectional view taken along the line BB ′ in FIG. 1, in which the magnetic fluid 26 is arranged in an elliptic ring so as to surround the variable throttle valve 8.

FIG. 4 is a sectional view taken along the line CC 'in FIG. As shown in this figure, the cross section of the flow rate measuring pipe line 6 is formed in a rectangular shape, and the variable throttle valve 8 of the same rectangular shape has a structure in which the fluid passage area is variable. The flow rate measuring pipe 6 is composed of an upper wall 7, a lower wall 28, and side walls 29 and 30.

In FIG. 1, the upstream pressure (P1) of the variable throttle valve 8 is from the pressure outlet 31 and the downstream pressure (P1).
2) is taken out from the pressure take-out port 32, and the pressure sensor 33
These differential pressures are detected at. The signal from the pressure sensor is sent to the flow rate calculation unit 21.

Next, the operation will be described. In the state of the variable throttle valve 8 shown in FIG. 1, it is assumed that the fluid flows in the flow rate measuring pipe 6 in the direction from a to b. The differential pressure before and after the variable throttle valve 8 (Δ
p) is detected by the pressure sensor 33 through the pressure outlets 31 and 32, and this signal is sent to the flow rate calculation unit 21. At this time, the opening h of the variable throttle valve 8 is determined by the position sensor 18 with respect to the reflection plate 20 mounted on the variable throttle valve 8.
This signal is also measured by the reflection from the flow rate calculation unit 21.
Sent to

On the other hand, in the flow rate calculation unit 21, the differential pressure (ΔP) -flow rate (Q) characteristic of the variable throttle valve 8 as shown in FIG. 5 is stored in advance with the opening h as a parameter. Therefore, for example, as a signal from the position sensor 18, the opening h
When the signal from the pressure sensor is Δp = Δp1 at −h1, the flow rate calculation unit 21 outputs that the flow rate is Q1, as shown in the graph of FIG.

Next, the pinion 12 is rotated by the rotation of the motor 11.
Is rotated and the rack 9 is pushed downward. At this time, if the opening degree h changes to h2 and the differential pressure Δp changes to Δp2, the flow rate shows a value of Q2 according to FIG.

By providing the variable throttle valve 8 in this manner, the differential pressure can be increased and measured at a small flow rate, so that an accurate flow rate value can be obtained.

In such a measurement, the seal structure of the variable throttle valve 8 affects the measurement accuracy, which is an important issue. A large driving force was required to perform this seal mechanically. The present invention solves this problem by using a magnetic fluid seal in this portion.

That is, in FIG. 1, since the variable throttle valve 8 is made of a magnetic material, the magnetic lines of force generated by the permanent magnet 23 are the pole piece 24, the magnetic fluid 26, the variable throttle valve 8, the magnetic fluid 27, and the pole piece 25. Returning to the permanent magnet 23 via the path of. As shown in FIG. 3, this magnetic fluid seal structure extends over the entire circumference of the variable throttle valve 8 to ensure the shutoff of the inside and outside of the flow rate measuring pipe 6. Thus, since magnetic fluid is used as the sealing method, reliable sealing can be achieved with a small driving force.

Next, a second embodiment will be described. 6 has the same configuration except for the magnetic fluid seal portion 20 of FIG.

In this case, the multi-stage magnetic fluid seal portion 34 is formed on the upper wall 7. Pole pieces 36 and 37 are arranged above and below the permanent magnet 35. Magnetic fluid 3
Reference numerals 8 and 39 are arranged between the variable throttle valve 8 made of a magnetic material and the pole pieces 36 and 37.

Further, pole pieces 41 and 42 are arranged above and below the permanent magnet 40. The magnetic fluids 43 and 44 are the variable throttle valve 8 and the pole piece 41, which are made of a magnetic material.
42 and 42.

The pole pieces 36, 37, 41, 42 are
The tip is tapered so that the lines of magnetic force are concentrated.

Next, the operation will be described. In FIG. 6, since the variable throttle valve 8 is made of a magnetic material, the lines of magnetic force generated by the permanent magnet 35 are the pole piece 36, the magnetic fluid 38,
It returns to the permanent magnet 35 through the path of the variable throttle valve 8, the magnetic fluid 39, and the pole piece 37.

The lines of magnetic force generated by the permanent magnet 40 are the pole piece 41, the magnetic fluid 43, the variable throttle valve 8,
It returns to the permanent magnet 40 via the path of the magnetic fluid 44 and the pole piece 42.

With the above two-stage magnetic fluid seal structure, even if the seal caused by the magnetic fluids 38 and 39 in the first stage is broken, the seal caused by the magnetic fluids 43 and 44 in the second stage can effectively operate, so that the reliability is higher. It is possible to provide a seal structure.

Next, a third embodiment will be described. In FIG. 7, a magnetic fluid seal portion 45 (second magnetic fluid seal portion) is provided on the lower wall 28 of the flow rate measuring pipe 6, and other portions are the same as those in FIG. .

The pole pieces 4 are provided on both sides of the permanent magnet 46.
7, 48 are arranged. The magnetic fluid 49 is arranged between the variable throttle valve 8 formed of a magnetic material and the pole pieces 47 and 48. Permanent magnet 46 and pole piece 47,
The portion surrounded by 48 is the nonmagnetic region 50.

FIG. 8 is a cross section taken along the line DD 'of FIG. Next, the operation will be described.

FIG. 7 shows a state in which the variable throttle valve 8 is lowered to the lowermost end in the flow rate measuring pipe 6. At this time,
The magnetic force lines generated by the permanent magnet 46 are the pole pieces 4
7, the magnetic fluid 49, the variable throttle valve 8, and the pole piece 48 to return to the permanent magnet 46. As shown in FIG.
Since the magnetic fluid 49 is arranged over the entire length of the tip portion 8a of the variable throttle valve 8 in the longitudinal direction, the flow can be effectively blocked by the variable throttle valve 8. When the variable throttle valve 8 is above the magnetic fluid 49, the magnetic circuit acts to hold the magnetic fluid 49.

When the flow is closed by the usual mechanical means, a large closing force is required, but in this case, it is fluidized by the magnetic fluid.
With a smaller closing force, a higher closing performance can be obtained than with mechanical methods.

Next, a fourth embodiment will be described. FIG. 9 shows the magnetic fluid seal portion 5 on the side walls 29 and 30 of the flow rate measuring pipe 6.
No. 1 (third magnetic fluid seal portion) is provided, and other portions than this portion have the same configuration as FIG.

The pole pieces 5 are provided on both sides of the permanent magnet 52.
3, 54 are arranged. The magnetic fluid 55 is arranged between the variable throttle valve 8 formed of a magnetic material and the pole pieces 53 and 54. Permanent magnet 52 and pole piece 53,
The portion surrounded by 54 is the nonmagnetic region 56.

FIG. 10 is a cross section taken along the line EE 'of FIG. Next, the operation will be described.

FIG. 9 shows a state in which the variable throttle valve 8 is lowered to the lowest end in the flow rate measuring pipe 6. At this time,
The magnetic force lines generated by the permanent magnet 52 are the pole pieces 5.
3, the magnetic fluid 55, the variable throttle valve 8, and the pole piece 54 are returned to the permanent magnet 52.

As shown in FIG. 10, this magnetic fluid 55
Are arranged over the entire circumference of the side portion 8b of the variable throttle valve 8, so that when the variable throttle valve 8 shuts off the flow, it is possible to effectively close the side leakage flow.
As a result, a higher closing performance of the variable throttle valve 8 can be obtained.

When the variable throttle valve 8 is above the magnetic fluid 55, the magnetic circuit acts to hold the magnetic fluid 54.

[0042]

As described above, according to the present invention, the following effects can be obtained. (1) Since the seal portion inside and outside the flow rate measuring pipe of the variable throttle valve has a magnetic fluid seal structure, the drive source of the variable throttle valve can be of small power. (2) Since the magnetic fluid seal portion has a multi-stage structure, the reliability of the seal with the outside can be further improved. (3) By providing the second magnetic fluid seal portion on the tip side of the variable throttle valve of the measuring pipe, even when the variable throttle valve is used as a closing valve, high closing performance can be obtained with a drive source of small power. . (4) By providing the third magnetic fluid seal portion on the side of the variable throttle valve of the measuring pipe, it is possible to further improve the closing performance when the variable throttle valve is used as a closing valve.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a differential pressure type flow meter according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line A-A ′ in the same flow meter.

FIG. 3 is a sectional view taken along the line B-B ′ in the same flow meter.

FIG. 4 is a sectional view taken along the line C-C ′ of the flow meter.

FIG. 5 is a characteristic diagram of the same flow meter.

FIG. 6 is a sectional view showing the configuration of a flowmeter according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing the structure of a flow meter according to a third embodiment of the present invention.

FIG. 8 is a sectional view taken along the line D-D ′ of the flow meter.

FIG. 9 is a sectional view showing the structure of a flowmeter according to a fourth embodiment of the present invention.

FIG. 10 is a sectional view taken along the line E-E ′ of the flow meter.

FIG. 11 is a cross-sectional view showing the configuration of a conventional flowmeter.

[Explanation of symbols]

 6 Flow Rate Measuring Tube 8 Variable Throttle Valve 12 Drive Section 18 Position Sensor 21 Flow Rate Calculation Section 22 Magnetic Fluid Seal Section (First Magnetic Fluid Seal Section) 33 Pressure Sensor 34 Multi-Stage Seal Section 45 Second Magnetic Fluid Seal Section 51 Third Magnetic fluid seal part

Claims (4)

[Claims] 1. A variable throttle valve for adjusting a flow rate in a flow rate measuring pipe, a drive unit for the valve, a position sensor for the valve, a pressure sensor for measuring a differential pressure across the valve, and the position sensor. And a flow rate calculating section for calculating a flow rate using a signal from a pressure sensor, and a differential pressure type flow meter in which a magnetic fluid seal section is provided in a partition inside and outside the measuring pipe in which the variable throttle valve moves. 2. The differential pressure type flow meter according to claim 1, wherein the magnetic fluid seal portion comprises a multi-stage seal portion. 3. A variable throttle valve for adjusting a flow rate in a flow rate measuring pipe, a drive unit for the valve, a position sensor for the valve, a pressure sensor for measuring a differential pressure across the valve, and the position sensor. And a flow rate calculation unit that calculates a flow rate using a signal from a pressure sensor, and the first magnetic fluid seal is provided on a partition inside and outside the measurement pipe in which the variable throttle valve moves in which the variable throttle valve moves. A differential pressure type flow meter in which a portion is provided and a second magnetic fluid seal portion is provided below the measuring tube. 4. A variable throttle valve for adjusting a flow rate in a flow rate measuring pipe, a drive unit for the valve, a position sensor for the valve, a pressure sensor for measuring a differential pressure across the valve, and the position sensor. And a flow rate calculation unit that calculates a flow rate using a signal from a pressure sensor, and the first magnetic fluid seal is provided on a partition inside and outside the measurement pipe in which the variable throttle valve moves in which the variable throttle valve moves. A differential pressure type flow meter in which a portion is provided, a second magnetic fluid seal portion is provided at a lower portion of the measurement pipe, and a third magnetic fluid seal portion is provided at a side portion of the measurement pipe.