JPS63100327A - Impeller type flow rate measuring instrument - Google Patents

Abstract

PURPOSE:To measure a flow rate up to a small flow rate range and to expand range ability by detecting the rotation of an impeller to which magnetic bodies are fitted by a detection coil, driving an oscillator connected to a resonance circuit with the output of the coil, and shaping the waveform of the detection output and counting it by a counter. CONSTITUTION:When fluid flows from piping 2 to piping 3, the impeller 5 has magnetic bodies 6 fitted to blades 5a rotates. Its rotation is detected by the detection coil 8. The oscillator 12 connected to the parallel resonance circuit 7 is driven with the output. The oscillation output of frequency which is nearly equal to the resonance frequency of the circuit and higher than the number of turns of the impeller 5 per second is outputted by the oscillator 12. The output signal is passed through an amplifier 13, a detecting circuit 14, and a waveform shaping circuit 16 and counted by a counter circuit 17 to measure the flow rate of the fluid.

Description

[Detailed Description of the Invention] [Industrial Application Field] Seikan IJI detects the rotational speed of an impeller placed in a fluid flow path and detects the flow of fluid. The present invention relates to an impeller type flow rate measuring device that measures , and particularly relates to an impeller type flow rate measuring device that can accurately measure up to a small flow rate range.

[Conventional technology]

The conventional impeller type flow i4 meter has a configuration as schematically shown in the third factor. In this figure 3, 'i' is placed at both ends? 2
The cylindrical housing 21 to which 2.23 is connected constitutes a flow path through which the wave body to be measured flows and an impeller accommodating portion that accommodates the impeller. Below the protruding portion 21a of the housing 21, there is provided a rotating impeller 25 on f+b24, and each blade 25a of the impeller 25 is provided with a magnet 2B.

Inside such a housing 21, pipes 22 to 23
When the fluid to be measured flows in the direction, the fluid hits the impeller 25 and one blade 3115 rotates in the direction of the arrow in the figure. The number of revolutions (rotation rate) of the impeller 25 per unit time is proportional to the flow rate (flow rate) of the fluid to be measured per unit time.

Further, a coil 27 is provided at a position facing the impeller 25 across the partition wall of the housing 21 made of a non-magnetic material.
is installed. As a result, when the magnet 2B attached to the blade 25a of the rotating impeller 25 passes near the coil 27, an electromotive force is generated in the coil 27, and by detecting this electromotive force, the impeller 2
5 rotation is detected.

The coil 27 is connected to an amplifier 28, and the electromotive force induced in the coil 27 is amplified by the amplifier 28. Then, the waveform shaping circuit 2S provided at the next stage shapes the signal into a rectangular wave. This rectangular wave signal is transmitted to the counter circuit 30
The number of revolutions of the impeller 25 is counted, and the amount of v1 of the fluid to be measured is measured.

[Problems to be Solved by the Invention] As described above, conventionally, the rotation of the impeller 25 is detected by detecting the electromotive force of the coil 27 that is generated when the magnet 28 attached to the impeller 25 passes over the front surface of the coil 27. This is what we do.

Therefore, in order to generate an electromotive force from the coil 27, the impeller 25 must be rotating at a certain speed, and as the rotation speed decreases, the electromotive force of the coil 27 decreases, causing the impeller 25 to rotate. becomes impossible to detect.

Therefore, conventionally the maximum measurable flow rate and the minimum vt;
,? The disadvantage was that it was difficult to achieve a range ability ratio of more than 5:1 at maximum.

Therefore, the present invention was proposed to solve these conventional problems, and provides an impeller type flow rate measuring device that can sufficiently measure up to the small illumination range of 71 and expand rangeability. The purpose is to

[Means for solving problems]

In order to achieve this object, the impeller type flow rate measuring device of the present invention has an impeller equipped with a magnetic material attached to the blades in a cylindrical housing made of a non-magnetic material connected to both ends of piping through which the fluid to be measured flows. is rotatably provided to be rotated by the flowing fluid to be measured, and a detection coil is provided outside the housing and in the vicinity of facing the impeller to detect rotation of the impeller from a change in inductance due to passage of the magnetic material. , a resonant circuit having this detection coil is provided, an oscillator is attached to this resonant circuit that oscillates a frequency that is sufficiently higher than the number of revolutions per second of the impeller and approximately equal to the resonant frequency of the resonant circuit, and the output terminal of the resonant circuit is connected to the resonant circuit. A detection circuit connected to the waveform shaping circuit is provided, a waveform shaping circuit connected to the detection circuit is provided to shape the detected output into a rectangular wave signal, a counter circuit connected to the waveform shaping circuit is provided, and the waveform shaping circuit is connected to the waveform shaping circuit. The method is characterized in that the flow rate of the fluid to be measured is measured by counting wave signals.

[Effect]

According to the present invention described above, when the impeller rotates and the magnetic body of the impeller approaches the detection coil forming the resonant circuit, the inductance of the detection coil changes, and the resonant frequency of the resonant circuit changes. Therefore, from the output end of this resonant circuit having the above-mentioned oscillator, a detection signal obtained by amplitude modulating the oscillation wave of the oscillator is obtained. It can be extracted without depending on.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The first factor is a configuration diagram of an impeller type flow rate measuring device showing an embodiment of the present invention.

In FIG. 1, piping 2.
3 is connected, and below the protrusion 1a formed on the housing l, there is an impeller 5 rotatably supported by the 4jh 4.
is provided. In this impeller 5 housed in the housing l, a magnetic body 6 is provided on each blade 5a.

In the impeller 5, when the Δ11 constant object flows from the pipe 2 to the pipe 3, the fluid to be measured passing through the housing l rotates in the direction of the arrow in the figure.

Further, a parallel resonant circuit 7 having a detection coil 8 for detecting the magnetic body 6 of the impeller 5 is provided. This parallel resonant circuit 7 consisting of a detection coil 8 and a capacitor 9 includes an oscillator 1
2 are connected in parallel, one connection point (point A) of this parallel connection is connected to the amplifier 13, and the other connection point (point B) is grounded. The oscillation frequency of the oscillator 12 is
A value sufficiently larger than the number of rotations per second of the impeller 5 (for example, 1
0 times or more). In addition, the parallel resonant circuit 7
The resonant frequency of is set approximately equal to the oscillation frequency of this oscillator 12.

Here, the detection coil 8 is provided outside the housing 1 made of a non-magnetic material and in the vicinity of the impeller 5, facing the impeller 5.

Therefore, when the impeller 5 rotates and the magnetic body 6 approaches the detection coil 8, the inductance of the detection coil 8 changes, and the resonant frequency of the parallel resonance circuit 7 changes. As a result, the output of the parallel resonant circuit 7 taken out between points AIj and B changes in the amplitude value of the oscillation wave of the oscillator 12 depending on whether or not the magnetic body 6 is close to it, as shown in Fig. 2a. The output is amplitude modulated as shown.

The output of the parallel resonant circuit 7 that detects the rotation of the impeller 5 is amplified by the amplifier 13. The amplified waveform is shown in FIG.

The output of the amplifier 13 is detected by a detection circuit 14 provided at the next stage, and as shown in FIG.

The detection output of the detection circuit 14 is supplied to a waveform shaping circuit 16 via a coupling capacitor 15. By passing through the capacitor 15, the waveform becomes a waveform with both polarities, as shown in FIG. 2d. Waveform shaping circuit! 8, the waveform is shaped into a rectangular wave. Note that the capacitor 15 must be set to a value that sufficiently covers the frequency band of the waveform at the minimum flow rate.

The waveform shaping circuit 16 is connected to a counter circuit 17 provided at the next stage, and the counter circuit 17 counts the rectangular wave signals to obtain an integrated value of the flow rate of the fluid to be measured.

In this manner, in the impeller-type flow rate measuring device described above, the inductance of the detection coil 8 that constitutes the parallel resonant circuit 7 changes with the rotation of the impeller 5 to which the magnetic body 6 is attached, and the resonant frequency of the parallel resonant circuit 7 changes. Since the rotation of the impeller 5 is detected by utilizing the change in the rotation of the impeller 5, it is possible to measure the flow rate even in a small flow range where the rotation of each impeller 5 is small, and the rangeability is expanded compared to the conventional method. can be achieved.

Note that it is also possible to directly connect the detection circuit 14 and the waveform shaping circuit 16 without using the coupling capacitor 15.

In addition, in the above-mentioned embodiment, an example was explained in which the integration amount is 1N and the amount is measured. ) The above impeller type flow rate measuring device can also be used to measure instantaneous flow rate. Even in this case, 1111 in the small IQ quantity range where the rotation speed of the impeller 5 is low
can be determined.

Further, instead of using the parallel resonant circuit 7, a series resonant circuit having a detection coil 8 may be configured, and the oscillator 12 may be attached to this series resonant circuit to detect the rotation of the impeller 5.

Effects of C-1j] As explained below, in the present invention, a resonant circuit having a detection coil for detecting the magnetic material attached to the impeller is provided,
An oscillator that oscillates at a frequency approximately equal to the resonant frequency is attached to this resonant circuit. Since the inductance of the detection coil changes as the magnetic body approaches, the resonant frequency of the resonant circuit changes, and the output of the resonant circuit is amplitude-modulated.

Thereby, a detection signal that detects the rotation of the impeller can be extracted from the output end of the resonant circuit.

In this way, in the present invention, since the rotation of the impeller is detected from the change in the inductance of the detection coil, the flow rate or instantaneous Flow rate measurement is easy, and rangeability can be expanded compared to conventional methods.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an impeller type flow measuring device showing an embodiment of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the impeller type flow measuring device, and Fig. 3 is a conventional impeller type flow measuring device. It is a structural diagram of a vehicle-type meteor meter. In the diagram: 1・φ・Housing 2.3@-・Piping 4・Shaft
5... Impeller Sa day/blade 8
・1 magnetic body 7...parallel resonant circuit 8 fist Φ・detection coil 301 capacitor 12th・oscillator 13...amplifier 14---detection circuit 15-φ
Conflict capacitor 18+1・Conflict waveform shaping circuit! ? ---・
counter circuit

Claims (1)

[Claims] An impeller with a magnetic material attached to its blades is rotatably provided in a cylindrical housing made of a non-magnetic material with pipes through which the fluid to be measured is connected at both ends, and the impeller is rotated by the flowing fluid to be measured. A detection coil for detecting the rotation of the impeller from a change in inductance due to the passage of the magnetic material is provided in the vicinity of the impeller, and a resonant circuit having this detection coil is provided. An oscillator that oscillates at a frequency that is sufficiently higher than the number of rotations per second of the impeller and approximately equal to the resonant frequency of the resonant circuit is installed, a detection circuit is provided that is connected to the output end of the resonant circuit, and a waveform that is connected to this detection circuit is provided. A shaping circuit is provided to shape the detection output into a rectangular wave signal, and a counter circuit connected to the waveform shaping circuit is provided to count the rectangular wave signal and measure the flow rate of the fluid to be measured. An impeller type flow measuring device featuring: