JP2907965B2 - Volume measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a volume measuring device for measuring a volume of a liquid to be measured contained in a tank.

[Prior art]

FIG. 2 shows an example of such a conventional volume measuring device. In the figure, 1 is a liquid, for example.
A main tank 2 for storing objects to be measured such as powders, granules, and irregularly shaped objects, and 2 is a correction tank that communicates with the main tank 1 via an orifice 3. Form. Reference numeral 4 denotes a cap that hermetically seals a tank unit including the main tank 1 and the correction tank 2, reference numeral 5 denotes a speaker that is a volume changing unit that changes the internal pressure of the main tank 1 and the correction tank 2, and reference numeral 6 denotes a sine wave signal. The oscillator 6 drives the speaker 5 by V ₀ sinωt. The oscillator 6 supplies the main tank 1 and the correction tank 2 with a sine wave signal V ₀ sinωt whose phase is inverted at regular intervals and supplies ΔVsinωt, ΔVsin (ωt +
π). 7a is a dynamic microphone for detecting a pressure change in the correction tank 2, and this dynamic microphone 7a generates a detection signal A ₁ sin (ωt + φ) according to a volume change. Where A ₁ is the amplitude value of the pressure change of the compensation tank.
7b a good condenser microphone sensitive than dynamic microphone 7a for detecting a change in pressure in the main tank 1, the condenser microphone 7b generates a detection signal -A ₂ sin (ωt + θ) in accordance with the volume change. Where A
₂ is the amplitude value of the pressure change in the main tank. Reference numeral 8 denotes a phase difference detection circuit. The phase difference detection circuit 8 detects a phase difference φ between the output signal V ₀ sinωt from the oscillator 6 and the detection signal A ₁ sin (ωt + φ) output from the dynamic microphone 7a. . Reference numeral 9 denotes a phase matching circuit, which outputs an output signal of the oscillator 6 to a phase difference detecting circuit 8.
The phase of the output of the dynamic microphone 7a is adjusted based on the phase difference between the detected outputs. 10 is the first multiplier,
This first multiplier 10 multiplies the detection output of the dynamic microphone 7a by the output of the phase matching circuit 9. Reference numeral 11 denotes a first zero-cross detection circuit. The first zero-cross detection circuit 11 outputs an integration start signal at a zero-cross at a certain point in time of the output of the dynamic microphone 7a, and then ends integration at the n-th zero-cross after a predetermined time t seconds. Output a signal. Reference numeral 12 denotes a first integrator that integrates the output from the first multiplier 10 based on the integration start signal and the integration end signal from the first zero cross detection circuit 11 and outputs γP ₀ V ₀ . 1
The integrator 12 does not output the integration output until the integration end signal comes. 13 is an inverting circuit for inverting the output from the phase matching circuit 9, and 14 is a second multiplier, which has the same function as the first multiplier 10. Reference numeral 15 denotes a second zero-cross detection circuit. The second zero-cross detection circuit 15 has the same function as the first zero-cross detection circuit 11. Reference numeral 16 denotes a second integrator. The second integrator 16 has the same function as the first integrator 12, and stops the integration when an integration end signal is supplied from the second zero cross detection circuit 15. And outputs γP ₀ V ₀ / V ₂ . 17 is a divider for dividing the output of the first integrator 12 at the output of the second integrator 16, the output of the divider 17 becomes a volume V ₂ of the hollow portion in the main tank 1. 18 is the total volume of tank 1
A subtractor to which V _T is set as a reference value and to which the calculation result of the divider 17 is supplied.The calculation result of the subtracter 18, that is, subtracting the volume V _{2 of the} hollow portion from the total volume V _T Is the volume _{VL of the} object to be measured in the main tank 1. Next, the operation will be described. First, the oscillator 6 drives the speaker 5 with a sine wave signal represented by V ₀ sinωt. As a result, the dynamic microphone 7a outputs the detection signal A ₁ sin (ωt + φ),
The condenser microphone 7b outputs the detection signal −A ₂ sin (ωt +
θ). The phase difference detection circuit 8 detects a phase difference φ between the sine wave signal V ₀ sinωt from the oscillator 6 and the detection output A ₁ sin (ωt + φ) from the dynamic microphone 7a. The output signal of the oscillator 6 is matched with the output of the dynamic microphone 7a by the phase matching circuit 9 based on the output phase difference. Next, the dynamic microphone 7a is
Is multiplied by the output of the phase matching circuit 9.
Then, the output from the first multiplier 10 is integrated in the first integrator 12 based on the integration start signal and the integration end signal from the first zero-cross detection circuit 11, and after reaching the integration end signal, the integrated value γP ₀ and it outputs the V _0. Further, the output from the phase matching circuit 9 is inverted by the inverting circuit 13 so that the output signal of the oscillator 6 matches the output phase of the condenser microphone 7b. The detection output of the condenser microphone 7b and the output of the inversion circuit 13 are multiplied by the second multiplier 14. Then, the output from the second multiplier 14 is integrated in the second integrator 16 based on the integration start signal and the integration end signal from the second zero cross detection circuit 15, and after reaching the integration end signal, the integrated value γP ₀ and outputs the V ₀ / V _2. Thereafter, the output of the first integrator 12 and the output of the second integrator 16 are divided by the divider 17 to obtain the main tank 1.
To calculate the volume V ₂ of the cavity portion of the inner. Then, the calculation result of the divider 17 is supplied to the subtractor 18, when subtracting the volume V ₂ of the cavity portion from the total volume V _T of the main tank 1 in the subtractor 18, the calculation result is the main tank 1 is the volume _{VL of the} measured object.

[Problems to be solved by the invention]

However, in such a conventional volume measuring device, the signal processing is based on the analog signal processing.
There is a problem that it is unsuitable in the case of using ICs. The present invention has been made to solve the above-described problems, and has as its object to provide a volume measurement device configured to perform signal processing suitable for digital processing.

[Means for Solving the Problems]

The volume measuring device according to the present invention includes a correction tank provided in communication with a main tank that stores an object to be measured, a volume changing unit that changes respective internal pressures of the main tank and the correction tank at a predetermined frequency, A first pressure sensor for detecting a pressure change in the tank, a second pressure sensor for detecting a pressure change in the correction tank, and a correlation value between a drive signal of the volume changing means and a detection output from the first pressure sensor. A first correlation means for calculating, a second correlation means for calculating a correlation value between a drive signal of the volume changing means and a detection output from the second pressure sensor, and a correlation value output from the second correlation means. Division means for dividing by the correlation value output from the first correlation means, multiplication means for multiplying the result of division by the division means by the volume value of the correction tank, and multiplication of the multiplication means The results are those made more a subtraction means for calculating the volume of the object housed in the main tank by subtracting from the total volume value of the main tank.

[Action]

The volume measuring device according to the present invention is provided with a correction tank in communication with a main tank that stores an object to be measured, and the internal pressure of the main tank and the correction tank is changed by volume changing means to change the pressure of the main tank and the pressure change of the main tank. The pressure fluctuation of the correction tank is detected by the first pressure sensor and the second pressure sensor, respectively, and thereafter, the correlation value between the drive signal of the volume changing means and the detection output from the first pressure sensor is calculated by the first correlation means. Further, a correlation value between the drive signal of the volume changing means and the detection output from the second pressure sensor is calculated by the second correlation means. Then, the correlation value output from the second correlation means is converted to the first value.
While dividing by the correlation value output from the correlation means, multiplying the result of the division by the volume value of the correction tank, and then subtracting the multiplication result from the total volume value of the main tank, the multiplication result is stored in the main tank. The volume of the measured object is calculated.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the same or equivalent components as in FIG. In the figure, reference numeral 19a denotes a first for detecting a pressure change in the main tank 1.
Ceramic microphone, the first ceramic microphone 19a generates a signal of KΔV / V _G + N _G according to volume change. Here V _G is the volume of the cavity portions other than the object to be measured in the main tank 1, K is a parameter that varies depending on the specific gravity of the ambient temperature and absolute pressure or gas, N _G is other than volume change ΔV factors (e.g. Pressure change component (noise) generated by vibration of the main tank). Reference numeral 19b denotes a second ceramic microphone for detecting a change in pressure in the correction tank 2, and the second ceramic microphone 19b generates a signal of KΔV / V _S + N _S according to a change in volume. Here V _S is the volume of the correction tank 2, N _S is the pressure change component caused by factors other than volume change [Delta] V (noise). Reference numeral 20 denotes a first correlation processing circuit which is a first correlation means.
Is the output signal (K · ΔV) of the first ceramic microphone 19a.
/ V _G + N _G ) and the output signal sinωt of the oscillator 6 to obtain only the amplitude value K · ΔV / V _S from which noise _NG generated due to factors other than the volume change ΔV is removed. 21 has the same function as the first correlation processing circuit 20, and the second
In the second correlation process circuit is a correlation means, the second correlation process circuit 21 is amplitude K · [Delta] V removing the N _S from the output signal of the second ceramic microphone _{19b (K · ΔV / V S} + N S) /
Outputs only V _S. Reference numeral 22 denotes an output signal K · ΔV / V _G of the first correlation processing circuit 20 and an output signal K · ΔV / V _S of the second correlation processing circuit 21.
In divider dividing by, the divider 22 outputs a V _G / V _S. 23 is a multiplier for multiplying the total volume V _S of the division result in the form of the output signal V _G / V _S to the correction tank 2 of the divider 22, the cavity other than the multiplier 23 is the object to be measured in the main tank 1 determining the volume V _G parts. 24 is a subtractor for subtracting the volume V _G, which is the output signal of the multiplier 23 from the total volume V _T of the main tank 1, the subtractor 24 outputs the volume V _L of the object. Next, the operation will be described. First, a drive signal sinωt of a predetermined frequency from the oscillator 6
Drives the speaker 5 to change the internal pressure of each of the main tank 1 and the correction tank 2. Then, the pressure fluctuation of the main tank 1 is detected by the first ceramic microphone 19a, and the pressure fluctuation of the correction tank 2 is detected by the second ceramic microphone 19b. Thereafter, the drive signal of the speaker 5 and the first
Correlation value K · ΔV with detection output from ceramic sensor 19a
/ V _G is calculated by the first correlation processing circuit 20, and the drive signal of the speaker 5 and the second ceramic microphone 19 are calculated.
a correlation value K · ΔV / V _S of the detection output from b is calculated by the second correlation process circuit 21. And the second correlation processing circuit
The correlation value K · ΔV / V _G output from the first correlation processing circuit 20 is divided by the correlation value K · ΔV / V _S output from 21, and the division result V _G / V _S The volume value of the correction tank 2 is multiplied, and the result of the multiplication is subtracted from the total volume value of the main tank 1 to calculate the volume of the to-be-measured object stored in the main tank 1. By performing volume measurement in this manner, volume measurement can be performed with high accuracy.

【The invention's effect】

As described above, according to the present invention, the configuration is such that the main tank for storing the object to be measured, the correction tank provided in communication with the main tank, and the internal pressure of each of the main tank and the correction tank are set to a predetermined value. Volume changing means for changing the frequency, a first pressure sensor for detecting a pressure change in the main tank, a second pressure sensor for detecting a pressure change in the correction tank, a drive signal for the volume changing means, and a first signal. First correlation means for calculating a correlation value with a detection output from the pressure sensor; second correlation means for calculating a correlation value between a drive signal of the volume changing means and a detection output from the second pressure sensor; Dividing means for dividing the correlation value outputted from the second correlating means by the correlation value outputted from the first correlating means; and the volume value of the correction tank for the result of division by the dividing means. A multiplying means for multiplying, and a subtracting means for subtracting the calculation result of the multiplying means from the total volume value of the main tank to calculate the volume of the DUT stored in the main tank. Thus, it is possible to obtain a circuit configuration suitable for realization, and to obtain an effect that volume measurement can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a volume measuring device according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional volume measuring device. 1 ... main tank, 2 ... correction tank, 5 ... volume changing means (speaker), 19a ... first pressure sensor (first ceramic microphone), 19b ... second pressure sensor (second ceramic microphone), 20 first correlation means (first correlation processing circuit), 21 second correlation means (second correlation processing circuit), 22 division means (divider), 23 multiplication means (multiplier) ), 24 …… Subtraction means (subtractor).

Claims (1)

(57) [Claims] A main tank (1) for storing an object to be measured.
A correction tank (2) provided in communication with the main tank; and a volume changing means (5) for changing the internal pressure of each of the main tank and the correction tank at a predetermined frequency.
A first pressure sensor (19a) for detecting a pressure fluctuation of the main tank based on the volume changing means, a second pressure sensor (19b) for detecting a pressure fluctuation of the correction tank based on the volume changing means, First correlation means (20) for calculating a correlation value between the drive signal of the volume change means and the detection output from the first pressure sensor; and a drive signal of the volume change means and a detection output from the second pressure sensor. A second correlating means (21) for calculating a correlation value between the first and second correlating means, and a dividing means (22) for dividing the correlation value output from the second correlating means by the correlation value output from the first correlating means Multiplication means (23) for multiplying the result of division by the division means by the volume value of the correction tank; and subtracting the calculation result of the multiplication means from the total volume value of the main tank and storing the result in the main tank. The volume of the measured object Subtraction means (24) and volume measuring apparatus equipped with a to.