JPH0670573B2 - Flowmeter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter, and more particularly to a flow meter for measuring the flow rate by detecting the number of rotations of a rotating body that rotates in accordance with the flow of fluid.

[0002]

2. Description of the Related Art As a flow meter of this type, for example, an impeller type flow meter, a rotary flow meter, an oval gear type flow meter,
There is a roots type flow meter. All of these have a rotor, such as an impeller, rotor, and rotor, which rotate with the flow of fluid, inside the base body, and the flow rate is based on the rotation speed of the rotor detected by the rotation speed detection mechanism. Is designed to measure.

As the rotation speed detecting mechanism, a magnet is attached to the rotating body, a magnetic sensor detects a change in the magnetic field due to rotation, or a black and white reflective seal is attached to the rotating body to rotate the optical fiber type sensor. There is one that detects a change in the amount of received light.

[0004]

By the way, since the magnetic sensor detects a change in magnetic field as a change in current or voltage, an optical fiber type sensor that does not use electricity is generally used in the case of explosion-proof specifications. .

However, if the fluid is a solvent or a chemical, an expensive optical fiber type sensor having chemical resistance must be used, and in the case of a colored fluid, the fluid hides the reflective seal. Therefore, there is an inconvenience that the rotation of the rotating body cannot be directly detected by the optical fiber type sensor.

For this reason, as shown in FIG. 5, the flow path, that is, the rotating body portion is completely cut off, and the detecting portion 70 which rotates synchronously with the rotating body 61 is separately provided outside the blocked rotating body 61. There is. That is, the rotating body 61 is provided with the magnet 62 and the disk 71 on which the black and white reflective seal 72 is attached is attached to the rotating body 61.
By rotatably supporting the iron plate 73 provided on the back surface of the disk 71 by the magnet 62,
The disc 71 is rotated in synchronization with the rotating body 61.

As described above, if the detection unit 70 is separately provided and the rotation of the rotating body 61 is indirectly detected, the number of parts is increased, the flowmeter main body is unnecessarily enlarged, and the detection reliability is lowered.

[0008] Also, with a normal colorless and transparent fluid, the rotation of the rotating body can be directly detected, but since the rotating body itself is in contact with the fluid, the reflection seal is contaminated and the light is refracted by the fluid. There is a drawback that the detection accuracy is lowered due to the change in the rate.

Therefore, an object of the present invention is to improve a rotation speed detecting mechanism in a flow meter of this kind in order to solve the above-mentioned inconvenience.

[0010]

In order to solve the above-mentioned problems, the present invention provides a flowmeter as described above, wherein the rotation speed detecting mechanism is provided on the rotating body, and a magnet for performing a rotary motion together with the rotating body. , An optical fiber magnetic sensor formed by interposing a Faraday element between a light projecting side optical fiber having a polarizer at the tip and a light receiving side optical fiber having an analyzer at the tip provided on the rotation orbit of the magnet. I did.

[0011]

In the flow meter constructed as described above, the optical fiber magnetic sensor detects a change in the magnetic field strength caused by the rotation of the magnet as a change in the amount of received light, so that the flow meter directly projects light to a rotating body or the like. There is no need, and even if an object such as a non-magnetic body is interposed between the optical fiber magnetic sensor and the rotating body, the rotation of the rotating body is directly detected as long as the magnetic field is transmitted.

[0012]

EXAMPLES Examples will be described below with reference to the drawings. As shown in FIGS. 1 to 3, this flowmeter is a rotary flowmeter including a flowmeter main body 1 and an optical fiber magnetic sensor 2.

The flowmeter main body 1 comprises an upper main body portion 30 having a mounting portion 31 for the optical fiber magnetic sensor 2 and a lower main body portion 10 having fluid passages 18 and 19, a measuring chamber 11 and a rotor 20. The flow paths 18 and 19 and the measuring chamber 11 communicate with each other through an inflow port 16 and an outflow port 17.

The measuring chamber 11 is a circular recess, and a guide groove 14 for the rotor 20 is formed in the center thereof by a protrusion 12 and an annular rising portion 13 provided on a concentric circle centering on the protrusion 12. There is. A partition wall 15 is provided between the inflow port 16 and the outflow port 17 between the outer peripheral surface 13 a of the rising portion 13 and the inner peripheral surface 11 a of the measuring chamber 11.

The rotor 20 comprises a cylindrical body 21 provided with a disc 22 at the upper end thereof. At the center of the disc 22, a mounting portion 23 for a magnet 25 projecting upward and a shaft 24 projecting downward are provided. And a slit 26 are formed in the cylindrical body 21.

When the slit 26 is inserted into the partition wall 15 and the shaft 24 is fitted into the guide groove 14, the outer peripheral surface of the cylindrical body 21 becomes the inner peripheral surface 11 of the measuring chamber 11, as shown in FIG.
The outer peripheral surface of the cylindrical body 21 is circumscribed by a and the rising portion 1
The rotor 20 is housed in the measuring chamber 11 while being inscribed in the outer peripheral surface 13 a of the rotor 3.

The rotor 20 housed in the measuring chamber 11 in this way rotates while the slit 26 and the shaft 24 move on the partition wall 15 and in the guide groove 14 while maintaining this state. Along with this, the magnet 25 also makes a circular motion around the protrusion 12 as with the shaft 24.

The optical fiber magnetic sensor 2 is mounted on the rotation path of the magnet 25 in the mounting portion 31 of the upper body 30.

In this optical fiber magnetic sensor 2, as shown in FIG. 4, a polarizer 54 and an analyzer 55 are respectively provided at the tips of a light projecting side optical fiber 52 and a light receiving side optical fiber 53 which are sealed in a housing 51. The Faraday element 57 is installed on the optical path of the light emitted from the light-transmitting side optical fiber 52, and is incident on the light-receiving side optical fiber 53 through the reflecting plate 56.

Therefore, the light emitted from the light projecting side optical fiber 52 is converted into linearly polarized light by the polarizer 54 and is incident on the Faraday element 57.
Since the plane of polarization of the linearly polarized light passing through is rotated in proportion to the magnetic field strength for the Faraday element 57, the analyzer 5
The light intensity of the linearly polarized light passing through 5 and emitted to the light-receiving side optical fiber 53 changes. That is, the change in the magnetic field strength can be detected as the change in the amount of received light.

In the flowmeter constructed as described above, the fluid that has entered from the flow path 18 on the inlet side flows into the measuring chamber 11 through the inflow port 16. The rotor 20 rotates toward the outlet 17 side due to the inflow pressure of the fluid, so that the fluid in the measuring chamber 11 is removed from the outlet 20.
7 is sent to the flow path 19 on the outlet side.

At this time, one rotation of the rotor 20 sends out the fluid corresponding to the volume of the measuring chamber 11, that is, the volume surrounded by the inner peripheral surface 11a of the measuring chamber 11 and the outer peripheral surface 13a of the rising portion 13. The flow rate is measured by measuring the rotation speed of the rotor 20.

The number of rotations of the rotor 20 is determined by the magnet 25 rotating with the rotor 20 and the optical fiber magnetic sensor 2
Since the magnetic field strength with respect to changes, the change is measured by the optical fiber magnetic sensor 2 detecting this change as a change in the amount of received light.

The structure of the flow meter is not limited to the illustrated rotary type, but may be an impeller type, an oval gear type, a roots type or the like.

[0025]

As described above, in the flowmeter of the present invention, the rotation speed detection mechanism of the rotating body is constituted by the magnet provided on the rotating body and the optical fiber magnetic sensor provided on the rotation track of the magnet, Since the change in the magnetic field strength caused by the rotation of the magnet is detected as the change in the amount of received light, it is not necessary to directly project light onto the rotating body unlike the conventional optical fiber type sensor often used in the conventional explosion-proof type.

Therefore, unlike the conventional case, there is no decrease in detection accuracy due to dirt such as a black and white sticker attached to the rotating body,
Further, even when light cannot be directly projected onto the rotating body, the number of rotations of the rotating body can be directly detected without separately providing a detection unit that rotates in synchronization with the rotating body, so that the detection reliability is high and the flow meter There is an advantage that the size itself is reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment according to the present invention.

FIG. 2 is an exploded plan view of the same as above.

FIG. 3 is a transverse sectional view of the above.

FIG. 4 is a schematic diagram showing the structure of the optical fiber magnetic sensor of the above.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flowmeter main body 2 Optical fiber magnetic sensor 10 Lower main body part 11 Measuring chamber 12 Protrusion 13 Rising part 14 Guide groove 15 Partition wall 16 Inflow port 17 Outflow port 18, 19 Flow path 20 Rotor 21 Cylindrical body 22 Disc 23 Mounting part 24 Shaft 25 Magnet 26 Slit 30 Upper Body 31 Mounting Part 51 Housing 52 Light Emitting Side Optical Fiber 53 Light Receiving Side Optical Fiber 54 Polarizer 55 Analyzer 56 Reflector 57 Faraday Element

Claims (1)

[Claims] 1. A base body having a fluid inlet and a fluid outlet is provided with a rotating body that rotates by the flow of the fluid and a rotation speed detection mechanism for the rotating body, and the flow rate is determined based on the detected rotation speed. In a flowmeter configured to perform measurement, the rotation speed detection mechanism has a magnet provided on the rotating body and rotating with the rotating body, and a projection provided with a polarizer at a tip provided on a rotation orbit of the magnet. A flowmeter comprising an optical fiber magnetic sensor in which a Faraday element is interposed between an optical fiber on the light side and an optical fiber on the light receiving side having an analyzer at the tip.