JPH0524017Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a mass flow rate indicator calibration device for calibrating the indication of a mass flow rate indicator, which is an instrument to be calibrated.

<Prior Art> A conventional calibration device for a mass flow rate indicator will be described below with reference to the drawings.

FIG. 4 is a schematic explanatory diagram of a conventional calibration device for a mass flow rate indicator.

In FIG. 4, E is an AC power supply that outputs, for example, 115V, 400HzAC (this numerical value will be used as an example in all explanations of the present application). 1 inputs a synchro signal from a mass flow transmitter (hereinafter abbreviated as "transmitter"), not shown, through which the fluid to be measured flows in the state in which it is actually used, and calculates the mass of the fluid to be measured, which is the instrument to be calibrated. This is a mass flow rate indicator (hereinafter referred to as an "indicator") that indicates the flow rate (the indicator includes, for example, a configuration that internally performs digital conversion and displays it digitally). This indicator 1 is connected to the
It consists of a receiving magnetine 2 consisting of a coil 2a excited with 115V400Hz AC and a rotor 2b, and an indicator 3 that operates in conjunction with the rotation of the rotor 2b. Reference numeral 4 denotes a mass flow rate indicator calibration device (hereinafter simply referred to as a "calibration device") which outputs a synchronized simulated signal (hereinafter referred to as a "simulated signal") as an electric signal to the coil 2a. This calibration device 4 is a standard oscillator for the indicator 1 to be calibrated. In order to output an arbitrary simulated signal, a setting section 5 is provided with, for example, a knob 5a and sets an arbitrary setting value, and a rotor that rotates (obtains a displacement angle) in conjunction with the rotation of the knob 5a. AC power supply E by 6b
a transmitting magnetine 6 which outputs a simulated signal through the connection from a coil 6a which is excited with 115V 400Hz AC and is connected to the coil 2a of the indicator 1;
Consists of.

<Problems to be solved by the invention> The calibration device is required to have high accuracy as a standard transmitter. However, in order to manufacture the above-mentioned conventional calibration device with high precision, high precision parts are required throughout, such as the coil 6a with no uneven winding and the magnet rotor 6b with high positional precision. Because of this, it is not easy to manufacture and is therefore expensive, and furthermore, since it has moving parts, there are problems in that severe maintenance is always required to maintain reliability.

The present invention was devised in view of the problems of the conventional technology, and utilizes means such as a generally commercially available digital synchro converter (hereinafter referred to as a "D/S converter"). It is an object of the present invention to provide a highly reliable mass flowmeter calibration device having no moving parts at a low cost.

<Means for solving the problem> The mass flow meter calibration device of the present invention for achieving the above-mentioned purpose is a mass flow meter calibration device that calibrates the indication of the mass flow rate indicator using a synchro simulation signal. , means for inputting a fundamental frequency to generate a reference signal consisting of a second harmonic; and a means for generating a reference signal consisting of a second harmonic by inputting the reference signal as one input and using a digital signal corresponding to the rotor position of the magnesine as the other input to vary the fundamental frequency. means for outputting a second harmonic simulated signal that changes with respect to the fundamental frequency from the means, and means for inputting and adding together the second harmonic simulated signal that changes with respect to the fundamental frequency and outputting a synchronized simulated signal. It is characterized by having the following.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings. In the following drawings, parts that overlap with those in FIG. 4 are given the same numbers and their explanations will be omitted.

FIG. 1 is a block diagram of a mass flow indicator calibration device which is a specific embodiment of the present invention.

In Fig. 1, 40 represents, for example, a fundamental frequency of 400Hz and a simulated second harmonic of 800Hz that changes with respect to this fundamental frequency (hereinafter referred to as "simulated second harmonic").
The calibration device of the present invention calibrates the indicated value by outputting a synchronized simulated signal (hereinafter referred to as "simulated composite signal") g, which is a synthesized signal consisting of a synthesized frequency with f) to the indicator 1.

The calibration device 40 has a fundamental frequency of 115V400, for example.
Means 41 inputs HzAC as a fundamental signal a and generates a reference signal e consisting of a second harmonic, and a digital signal Din corresponding to the angle (position) of the magnesine rotor takes the reference signal e as one input.
as the other input, and outputs a simulated second harmonic signal f (individually f ₁ to f ₃ ), for example, a commonly available D/S converter 42 (Scott transformer, cos/sin multi Consists of pliers, phase shift detection circuit, etc.For detailed structure and operation, please see, for example, Electronics Digest, April 1976 issue "Special Feature A/
D/D/A converter applied technology, pages 15 to 21, so the following is omitted), the simulated second harmonic signals _f1 to _f3 , and the fundamental frequency a are input, and these inputs are added. and means 44 for outputting a simulated composite signal g (individually g ₁ to _{g 3} ) to each tap of the coil 2a to which the 115 V 400 Hz AC of the receiving magnetine 2 of the indicator 1 is excited. In addition, 43a to 43c are D/
This is an amplifier circuit that amplifies the signals f ₀₁ to _{f 03} from the S converter 42 .

Here, means 41 for generating the reference signal c
consists of an attenuator 41a that attenuates the fundamental signal a, and a squaring circuit 41b that inputs the signal b from the attenuator 41a and converts the fundamental frequency of 400Hz into the second harmonic of 800Hz.
A DC cut filter 41c cuts and filters the DC component of the signal c from the square circuit 41b, and a signal d from the DC cut filter 41c is inputted to a predetermined phase (D/S converter 42 converts the digital signal D in and a phase shift circuit 41d that outputs a reference signal e by shifting the phase so as to have a phase detection phase for comparison with a signal based on the reference signal e.

Further, the means 44 for outputting the simulated composite signal g includes, for example, windings T _1a , T _2a , ~, T _1c , respectively on the primary side.
T _2c is a transformer with windings T _3a to _{T 3c} on the secondary side
It can be composed of T _a ~ T _c . Simulated second harmonic signals f ₁ to f ₃ are applied to the primary windings T _1a to T _1c .
is guided, and a basic signal _{a a} consisting of a voltage of 1/3 of 115V400HzAC is guided to the primary windings T _2a to T _2c via the resistor R, and as a result, the secondary windings T _3a to T _3c
From, the fundamental signal a _a and the simulated second harmonic signal f ₁ ~ _{f 3}
Simulated composite signals g ₁ to _{g 3} which are composite outputs are output.

FIG. 2 is a signal waveform diagram for explaining the operation of FIG. 1.

The explanation will be continued below with reference to FIGS. 1 and 2.

FIG. 2a is the basic signal a. This basic waveform a
is attenuated by the attenuator 41a to become an attenuated signal b of, for example, ±10V400Hz as shown in FIG. 2b. This attenuated signal b is 2
The signal is guided to a multiplier circuit 41b, and is extracted as a second harmonic signal c of 800 Hz with a shifted zero point as shown in FIG. 2c. The DC component of this second harmonic c is cut filtered by a DC cut filter 41c to obtain a filtered second harmonic signal d as shown in FIG. 2d. In order to make the phase of this second harmonic signal d the same as a predetermined phase, a phase shift circuit 41
d to obtain a reference signal e as shown in FIG. 2e. Specifically, the reference signal e is
For example, the phase of the second harmonic signal d is adjusted in the phase shift circuit 41d so that it has the same phase as the reference phase when the flow rate indicated by Din input to the D/S converter 42 is zero, as shown in FIG. Adjust the phase shift as shown in . The D/S converter 42 receives the reference signal e shown in FIG. 2e as one input, and uses the digital signal Din corresponding to the angle (position) of the magnetine rotor as the other input, and performs a simulation as shown in FIG. 2f. The second harmonic signals f ₁ to _{f 3} are outputted to the primary windings T _1a , T _1b and T _1c of the means 47 via the amplifier circuits 46a to 46c. Since the basic signal a _a is guided to the primary windings T _1b , T _2b , T _2c of the means 47, the secondary windings T _3a -
From T _3c , the simulated composite signals g ₁ to _{g 3} as shown in Figure 2 g, which are the sum of these two inputs, are generated, i.e., the fundamental frequency of 400Hz (see waveform A in Figure 2 g) and the simulated second harmonic. A simulated composite signal as shown in waveform c in Figure 2g, which is a composite frequency voltage output with the signal (see waveform b in Figure 2g), is output to each tap of the coil 2a of the receiving magnetine 2 of the indicator 1. Ru. Here, the second harmonics of the simulated composite signals g ₁ to _{g 3} have different phases, respectively.
They differ by 120°. Therefore, the simulated composite signal g ₁
Based on ~ _g3 , the indicator 1 can indicate an accurate calibrated mass flow rate.

However, the present invention is not limited to the above explanation. For example, the fundamental frequency may be a frequency other than 400 Hz, and the second harmonic in this case naturally corresponds to this fundamental frequency. Also, means 4
In addition to the structure of the transformers T _a to _{T c} as shown in FIG. 1, for example, as shown in the diagram for explaining another embodiment of the present invention in FIG. ₁ , resistors _R1 to _R3 , an isolation transformer _Tx , and the like.

<Effects of the invention> As described above, the invention has been specifically explained along with the embodiments. According to the calibration device for a mass flow indicator of the invention, there is no need for a movable part like the magnesine method, and the structure is simple. Since it is composed of electronic circuits, it is possible to realize a product that has high reliability, is easy to manufacture, and is inexpensive. In addition, there is an effect that maintenance becomes easier.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a calibration device for a mass flow indicator which is a specific embodiment of the present invention, and Fig.
Figure 3 is a signal waveform diagram for explaining the operation of the present invention; Figure 3 is a diagram for explaining other embodiments of the present invention;
The figure is a schematic explanatory diagram of a conventional calibration device for a mass flow rate indicator. 1... Mass flow indicator (indicator), 4, 40...
...Calibration device for a mass flow rate indicator, 41... Means for generating a reference signal, 42... Means for outputting a simulated second harmonic signal (simulated second harmonic signal) that changes with respect to the fundamental frequency, 47... ...Means for outputting a synchronized simulated signal (simulated composite signal).

Claims (1)

[Scope of utility model registration request] In a mass flow indicator calibration device that calibrates the mass flow indicator indication using a synchronized simulated signal,
means for inputting a fundamental frequency to generate a reference signal consisting of a second harmonic; and a means for generating a reference signal consisting of a second harmonic by inputting the reference signal as one input and using a digital signal corresponding to the rotor position of the magnetine as the other input to vary the reference signal with respect to the fundamental frequency. means for outputting a second harmonic simulated signal; and means for inputting and adding the second harmonic simulated signal that changes with respect to the fundamental frequency from the means, and outputting a synchronized simulated signal. A calibration device for a mass flow rate indicator, comprising: