JPS5850419A - Device for detecting flow rate and flow rate changing rate - Google Patents

Abstract

PURPOSE:To obtain the highly reliable device which can detect the flow rate and the flow rate changing rate of fluid by one detecting device, by detecting the displacement and its rate of change of a movable orifice in a pipe through coils provided on the outer wall of the pipe. CONSTITUTION:In the pipe 1, wherein the fluid flows, a fixed orifice 2 and the movable orifice 6, which is moved in the inside of the pipe 1 by the differential pressure yielded before and after a restrictor in repsonse to the flow rate of the fluid, are provided, and an area flowmeter is constituted. The movable orifice body 6A is made of a magnet of a ferromagnetic body. A tip 6B of the movable orifice is formed by a nonmagnetic body. Furthermore, a primary coil 8 for AC excitation, which is wound along the moving range of the movable orifice 6 and two detecting secondary coils 10 and 11 which detect the moving displacement and its rate of change of the movable orifice 6 are provided on the outer wall of the pipe 1. Said secondary coils 10 and 11 are connected to a computing device 12. The displacement and the component of its rate of change of the orifice 6 are separately outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an area flow meter, and more particularly to a flow rate and flow rate change detection device suitable for detecting the flow rate and flow rate change rate of a fluid flowing in a pipe.

As a conventional surface-a flowmeter, one in which a moving body is provided inside a pipe through which fluid passes and the displacement of this moving body is detected by electrical means is generally used.

Conventional flowmeters such as those described above merely detect the flow rate of fluid flowing within a pipe.

When applying a flowmeter with this type of structure to a hydraulic servo system and using it as a detection means for feedback control, it is possible to perform only flow rate feedback, and there is no way to measure the rate of change in flow rate. control performance could not be improved. Or t
There is a method of measuring other physical quantities corresponding to the rate of change of the quantity and feeding it back, but this requires two detection devices, which makes the device complex, and causes problems in terms of responsiveness, safety ratio, 4 degrees, etc. However, various problems arose and the reliability of measurements was impaired.

The present invention has been made based on the above-mentioned matters, and when applied to feedback control of a servo system, etc., the present invention has a high reliability that allows accurate detection of fluid flow rate and flow rate change rate with - number of detection devices. It is an object of the present invention to provide a fluid flow rate and flow rate change rate detection device.

In order to achieve the above object, the present invention includes a fixed orifice provided in a pipe through which fluid flows, and a constriction formed together with this fixed orifice, and a pressure difference generated before and after the constriction depending on the flow rate of the fluid. l:i moving inside the tube
In the areal flow needle equipped with a T excitation orifice, the movable orifice body is a ferromagnetic magnet, and the tip of the movable orifice body is formed by a non-magnetic orifice,
Connected to the outer wall of the tube is a primary coil for alternating current excitation wound around the movement area of the movable orifice, and an arithmetic device that separates and outputs the movement displacement of the movable orifice and its rate of change component. However, a signal output proportional to the fluid flow rate and a signal output proportional to the fluid flow rate change rate are taken out from this secondary coil for detection.

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

FIG. 1 is a sectional view showing the structure of one embodiment of the apparatus of the present invention. In this figure, inside a non-magnetic stainless steel tube 1 through which the fluid through which the flow rate and flow rate change rate are to be measured passes, a fixed orifice 2 symmetrical to the tube axis is supported by a pair of left and right rods 3A and 38. Plate 4A and 4B
installed on. Each support plate 4A, 4B has a flow hole 5
A and 5B, and is fixed to the inner wall of the tube 1.

On the other hand, a movable orifice 6 consisting of a movable orifice body 6A and an orifice 6B shaped to form a constriction between a magnet made of a ferromagnetic material and the fixed orifice 2 is attached to the tube 1. They are provided so as to be movable in the left and right directions in the figure along the central axis -W1 when the spring 7 is acting with the inner wall as a guide. In addition, an orifice 6B made of a non-magnetic material that operates integrally with the movable orifice body 6A is provided at the tip of the movable orifice body 6A. This is to prevent movement from being hindered.

A primary coil 8 for alternating current excitation necessary for detecting displacement of the movable orifice 6 is provided on the outer wall surface of the tube 1 . An AC voltage source 9 is connected to the primary coil 8 . On the other hand, on both left and right sides of the primary coil 8 for AC excitation,
The movement of the movable ori-swiss 6A in the right direction and pressure side direction in the figure is detected respectively, and signals corresponding to the amount of movement and &(
Secondary coils 10 and 11 for detection are provided, respectively, for outputting signals corresponding to the rate of change, that is, the velocity of the movable orifice 6. 12 is a secondary coil 10J for detection
? This is an arithmetic device that extracts the outputs from and 11 and separates the displacement of the movable orifice 6 and its rate of change, that is, the velocity component. 13 is 7 lunges for mounting. The arithmetic unit 12 mentioned above will be described in detail later.

In the embodiment of the device of the present invention described above, for example, when hydraulic oil flows in from the flow holes 5A or 5B of the support plates 4A, 4B of the pipe 1, the movable orifice 6 is moved in accordance with the differential pressure across the throttle 9 due to the flow rate. moves to the right or left in the diagram. The displacement and speed of the movable orifice 6 due to the movement of the movable orifice 6 made of a ferromagnetic magnet are detected by the secondary coils 10 and 11 for detection, and the arithmetic unit 12
The displacement and velocity components of the movable orifice 6 are separated. These two output signals are used as a flow rate feedback signal and a flow rate change rate feedback signal for the servo system, and are also used independently to measure the flow rate and flow rate change rate.

Next, the specific operating principle of the arithmetic unit 12 will be explained with reference to FIG. 42 and FIG. FIG. 2 shows an isometric electric circuit consisting of a primary coil 8 for AC excitation, secondary coils 10 and 11 for signal detection, a movable orifice body 6A, and an orifice 6B. When an AC voltage is applied to the primary coil 8 by the AC voltage source 9, if the movable orifice 6 changes by xf from the neutral position, the inductive starting pressure E11 E2 occurs in the secondary coils 10 and 11 for detection. becomes as follows.

Here, d is the coil diameter B, magnetic flux density generated by the movable orifice made of a magnet, t is the total length of the movable orifice 6, and a is the distance between the coils of the secondary coils 10 and 11 for detection.

(2) is the current flowing through the primary coil 8, and n is the coil winding of each of the secondary coils 10 and 11.

It can be seen that the first term in equations (1) and (2) corresponds to the velocity of the movable orifice 6, and the second term corresponds to the displacement component of the movable orifice 6.

FIG. 3 shows a block diagram for separating the voltages in which the displacement and velocity components of the movable orifice 6A induced in the detection secondary coil 10.11 are superimposed. In this FIG. 3, the output voltage E of the secondary coils 10 and 11 for detection
, ,E, via a follower 14.15 to a synchronous rectifier 16.
17, the synchronization values are individually passed, and both numbers 1d after synchronization in step 7 are reduced in value by a subtracter 18, passed through a low-pass filter 19, and amplified by an amplifier 20 to obtain a DC voltage signal of the displacement of the movable orifice 6A. be able to.

Next, the output signals E1 and E of the secondary coils to, ii for detection are subtracted by a subtracter 21, passed through a low-pass filter 22, and amplified by an amplifier 23, so that the movable orifice 6 is The speed can be extracted as a DC '11 signal.

By detecting the displacement and velocity of the movable orifice 6 in the tube 1 in this way, an output proportional to the flow rate and flow rate of the fluid passing through the tube 1 can be generated. It is necessary that the opening area S of the diaphragm υ formed by the movable orifice 6 has an appropriate functional form with respect to the movement amount X of the movable orifice 6. Here, the flow rate Q, the pressure receiving surface A of the movable orifice 6, the moving distance
P and the flow rate coefficient C1 and the density ρ of the fluid, a relationship p is established as shown by the following equation.

AΔP2KX・・・・・・・・・
・・・・・・・・・・・・(4) (K: Spring constant) Equations (3) and (4) above, where, (5(X)=βVY in 5 formations...・・・・・・・・・
・・・・・・・・・・・・・・・ (6) Then, the change of the movable orifice 6 (fl-x is proportional to the flow rate Q. Also, the velocity dx of the movable orifice 6
/dt is proportional to the fluid flow rate dQ/dt. Here, the speed of the movable orifice 6 is (1)
As shown in equation (9) or equation (0), it is determined by the magnetic flux density of the magnet (9), so if the six movable oriswises are made of ferromagnetic magnets, even minute speeds can be detected. Therefore, it is possible to provide a device that can detect even minute flow rates of fluid and detects flow rates and flow rate changes with high sensitivity.

In the embodiment of the present invention described above, a diaphragm consisting of a fixed orifice 2 made of a non-magnetic material and a movable orifice 6B made of a ferromagnetic material is used, and the diaphragm before and after the diaphragm according to the flow rate of the fluid to be measured is used. A flow rate and flow rate change rate detection device is configured to detect the flow rate Wb from the amount of movement of the movable orifice 6 that is displaced in accordance with the differential pressure and the rate of change from the velocity amount of the movable orifice 6. ]' An arithmetic device 12 is provided to distinguish between the displacement and speed of the dynamic orifice 6.

Since a single detector is used to extract the output as a flow rate value for feedback control of a servo system, a flow rate change method, and a value of fL, it is possible to use a detection mechanism such as the conventional combination of a follower and potentiometer. It is possible to prevent a decrease in measurement integrality due to unsmooth operation. Also,
Conventional flowmeters do not have a means to measure the rate of change in flow rate without differentiating the flow rate, but according to the present invention, the flow rate can be measured over a wide range of flow rates and changes in flow rate, from low flow rates to large flow rates. It is possible to detect the rate. Furthermore, since two types of fluid amounts can be detected with one detection device, the detection device becomes compact. Furthermore, since the tip of the movable orifice 6 of the magnet has a non-magnetic orifice integrated with the movable orifice 6, the operation of the movable orifice 6 may be obstructed by adhesion of iron powder, etc. mixed in with the hydraulic fluid. do not have. Furthermore, the shape of the fixed orifice 2 is processed so that the aperture opening area and the moving amount of the movable orifice have an appropriate functional form, so that the detected value proportional to the flow rate and the detected value proportional to the rate of change of the flow rate can be obtained. Obtainable. Therefore, the flow rate and flow rate change rate detection device according to the present invention can be widely applied not only when using these signals for feedback control of a servo system but also to measuring the flow rate and flow rate change rate of the fluid in -a. can.

In addition, as a method for detecting the rate of change in flow rate of a fluid, the method of the present invention in which the core is made of a magnet can be used.
This method can also be used when applying a superimposed voltage of 4 AC voltage and 1 DC voltage to the next coil.

As described above, according to the present invention, a single detection device can detect flow rate and flow rate change with high accuracy.4. All can be detected.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the flow rate and flow rate change rate detection device of the present invention, and Fig. 2 is an electrical circuit diagram with equal restrictions of the movable orifice, primary coil, and secondary coil portion used in the present invention. , FIG. 3 is a block diagram showing an arithmetic device for separating output signals of flow rate and flow rate change rate. l...Pipe, 2...Fixed orifice, 6...Movable orifice, 6A...Movable orifice body, 6B...
Non-magnetic orifice, 7...Spring, 8...Primary coil, 9...AC source, IO, 11...Secondary coil for detection. 12... Arithmetic device, 1, 4, 15... Follower, 16
゜17...Synchronous rectifier, 18.21...Subtractor, 1
9゜22...Low pass filter, 20.23...Drum width filter. (12)

Claims (1)

[Claims] A fixed orifice provided in a pipe through which fluid flows, and a movable orifice that forms a restriction together with the fixed orifice and moves inside the pipe by a differential pressure generated before and after the restriction depending on the flow rate of the fluid. In area flowmeter,
The movable orifice body is a ferromagnetic magnet, the tip of the movable orifice body is formed by a non-magnetic orifice, and an AC excitation coil is wound on the outer wall of the tube along the movement range of the movable orifice. A primary coil and two secondary coils for detection are provided to detect the displacement of the movable orifice and its rate of change, and the secondary coil detects the displacement of the movable orifice occurring in the secondary coil and its rate of change component. What is claimed is: 1. A flow rate and flow rate change rate detection device, characterized in that it is connected to an arithmetic device that separates and outputs the flow rate and flow rate change rate.