JP2921495B2 - Filling method for liquid contents - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling a container, such as a can or a bottle, with a fixed amount of a liquid content, for example, a liquid for beverages, and more particularly, measuring the liquid content using an electromagnetic flow meter. The present invention relates to a method for filling a liquid content which is effective when implemented in a filling device.

[0002]

2. Description of the Related Art When filling liquid contents, for example, beverage liquids such as beer and carbonated beverages into cans and bottles,
It is necessary to measure the filling amount and fill the fixed amount at a time.
Therefore, various types of filling apparatuses have been developed, and a typical one is a liquid level control type, a chamber type, or an in-process volumetric type using various flow meters. Of these, filling using various flow meters from the viewpoint that it is easy to change the filling amount in response to the recent diversification of container shapes and capacities, and from the viewpoint of simplifying the device structure and facilitating maintenance, etc. The device is receiving attention.

[0003] As a flow meter used for the filling device, a turbine type flow meter which inserts an impeller into a flow path and measures the flow rate according to the rotation speed of the impeller, and vertically inserts a rod into the flow path to form a Karman vortex. Vortex type flow meter that measures the vortex period of the vortex and obtains the flow rate from that period, and electromagnetic flow meter that uses Faraday's law of electromagnetic induction, etc. An electromagnetic flowmeter having the characteristics of no response and quick response seems to be the best.

Japanese Patent Application Laid-Open No. 63-218003 discloses an electronic conversion circuit in which an electromagnetic flowmeter provided in a liquid supply pipe outputs various electric signals depending on the flow velocity through the flowmeter due to the Faraday effect, and this signal is input. Converts to a square pulse,
The counter counts these pulses, and when the count reaches the set number set in the counter, the electronic circuit sends a signal to a solenoid valve inserted into the supply pipe to close the valve, and a certain amount is set. An apparatus for filling a container with a liquid is disclosed.

The present inventors have disclosed in Japanese Patent Application Laid-Open No. 63-218003.
An apparatus was manufactured based on the invention of Japanese Patent Application Laid-Open Publication No. H11-209, and an experiment of filling a container with liquid was performed. However, even if the valve is closed when counting the set number of pulses, there is a variation in the amount of liquid filled in the container, and this variation is large and exceeds the allowable range. Could not.

[0006]

The inventors of the present invention have conducted intensive studies on the causes of the failure of the experiment conducted based on the invention disclosed in Japanese Patent Application Laid-Open No. 63-218003. I found that there was. That is, in a device that fills a container or the like with a fixed amount of liquid using an electromagnetic flowmeter, an electromotive force that is proportional to the flow velocity output from a detector of the electromagnetic flowmeter is A / D-converted by the converter, and the voltage is further increased. The pulse is converted to a pulse (usually a square wave) having a frequency proportional to the value and then output. At this time, the operation of pulse conversion is
The sampling is performed at a certain fixed sampling interval (the reciprocal is called a sampling rate). For example, when the flow rate per unit time is 200 ml / s, the frequency of the output pulse is 200 Hz
Is set so that the weight per pulse is 200/200 = 1.0 ml / pulse. In other words, one pulse is output when 1.0 ml flows,
If it is desired to fill 350 ml, it is sufficient to count 350 pulses. Actually, when filling 350 ml due to delay of operation, for example, 320 ml
Close the valve when ml has flowed.

What is important here is not how the flow rate expected from the number of pulses is equal to the actual flow rate, but how good repetition reproducibility is. Also,
Since the flow meter used for filling rapidly rises from zero flow to a certain value unlike monitoring the flow rate of a steady flow, in this case, when the sampling rate is slower than the rising speed, the output for the actual flow rate It was found that the accuracy of the applied pulse became poor.

[0008] When the sampling rate of the pulse conversion is low with respect to the rise rate of the flow rate, the cause of the deterioration of the filling accuracy (variation) has been pursued. Was input with a phase difference, and secondly, that the rising speed of the flow rate was different every time. Each is described in detail below.

[0009] the flow rate of the liquid flowing through the flow meter (was close to the results this curve experiments) assumed to rise in a sine curve as shown in FIG. 3 Then, time rise time indicated by the time t _p Becomes

FIG. 4 explains the cause of the variation due to the phase difference, which is the first cause.
msec, the sampling interval of the pulse conversion is 100 msec, and the flow rate per unit time q = 200 ml / s, it is assumed that the output pulse frequency f = 100 Hz. In this case, the weight per pulse is 200/100 = 2.0 ml / pulse, and when filling 40 ml, the filling valve may be closed when the 20th pulse is output. Therefore, when the flow rate is input with a certain phase difference for sampling every 100 msec, the actual flow rate (integration of the flow rate q per unit time) when the 20th pulse is output is calculated. is there.

When the phase difference is 0 msec, q = 0 at time t = 0 msec, and the output pulse is also zero. t = 100ms
In ec, q = 200 ml / s, and 10 pulses of f = 100 Hz are output for 100 msec until the next sampling. Thus, the output of the 20th pulse is at t = 2
At 90 msec, the actual flow rate V = 48.0 at this time
ml. Although the difference between the expected flow rate of 20 pulses and the expected flow rate of 40 ml is as large as 8.0 ml, as described above, the magnitude of the difference is not a problem, and the same difference is maintained regardless of the number of fillings. That is, reproducibility is important.

However, assuming that the flow rate rises with a delay of 20 msec from the sampling timing, when t = 100 msec, q ≒ 180.9 ml / s, and f = 100 × (180.9 / 200) = 90 .4
Nine pulses of 5 Hz are output for 100 msec.
Then, since q = 200 ml / s at t = 200 msec, f = 100 Hz, and 10 pulses are output at 100 msec. Therefore, the 20th pulse is output at t = 300 msec, and V = 46.0 ml. As a result, when the phase is zero, the deviation from the expected flow rate is 8.0 ml, but varies to 6.0 ml.

When the phase difference is 60 msec, t = 100
In msec, q ≒ 69.1 ml / s, and f = 100 × (69.
1/200) = 34.55 Hz pulse is output for 3 pulses during 100 msec. From the next sampling, f = 1
00 Hz. The 20th pulse is output when t = 360 msec, V = 50.0 ml, and the deviation is 10.0 ml.

As described above, when the input timing of the rising signal of the flow rate is shifted with respect to the sampling timing, the deviation between the flow rate value expected from the pulse number and the actual flow rate varies, thereby deteriorating the filling accuracy.

FIG. 5 explains the second cause, which is caused by the difference in the rising speed of the flow rate every time. Assuming the same conditions as in FIG. 4, the phase difference is zero,
The rise time t _p is different flow rate is that you entered.
flow rate of V = 4 at the time of t _p = 150msec at 20 th pulse
9.0 ml and V = 48.0 m at t _p = 100 msec.
At l, t _p = 50 msec, V = 53.0 ml, and the deviation from the expected flow rate varies from 8.0 to 13.0 ml.

In pursuit of the cause of these variations, the sampling rate was too slow for the rising speed, and the flow rate at the rising portion was not sufficiently grasped. The present inventors have found that there is something.

The present invention has been made in view of the above circumstances, and when measuring the amount of liquid content to be filled in a container with an electromagnetic flowmeter, the variation is minimized.
It is an object of the present invention to provide a method for filling a liquid content, which has enabled the practical use of a filling device equipped with an electromagnetic flowmeter.

[0018]

Means for Solving the Problems To achieve the above object, the present inventors have solved the above problems by focusing on the sampling rate of the pulse conversion calculation and the flow rate of the liquid content flowing through the flow meter. That is, the invention according to claim 1 of the present invention measures the flow rate of the liquid content with an electromagnetic flowmeter when the liquid content is supplied and filled into a container at a predetermined flow rate. The output proportional to the flow rate signal is calculated at a predetermined sampling rate, converted into an electric signal, and the electric signal is integrated. When the integrated value reaches a preset value, the filling valve is closed. A liquid content filling method in which the supply of the liquid content is stopped, wherein the sampling rate of the calculation when converting the output proportional to the flow rate into an electric signal is faster than the rising speed of the flow rate signal to be measured. There is as a method.
According to such a method, the sampling rate is sufficiently increased, the flow rate signal whose rise changes relatively sharply is accurately measured, and accurate filling can be performed.

Further, in the method according to the present invention, the conversion into the electric signal is a conversion into a pulse signal, and the integration is a counting of the pulse signal. When the signal from the electromagnetic flowmeter is converted into a pulse signal and the subsequent calculation is performed as in this method, calculation processing and the like can be performed easily and quickly.

Further, in the method according to the third aspect, the sampling rate of the calculation at the time of conversion into the pulse signal is set to about 20 to 100 Hz. According to such a method, the sampling rate is sufficiently high with respect to the rapidly changing flow rate signal, and the flow rate at the rising portion can be accurately measured.

Further, in the method according to the fourth aspect, the flow rate of the liquid content is about 0.3 to 1.2 m / s.
According to such a method, an accurate and stable measurement result can be obtained without being adversely affected by the flow velocity.

[0022]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram of an apparatus for performing a method according to an embodiment of the present invention. Since the present invention can be applied to all known filling devices that can use an electromagnetic flow meter, details of the filling device are omitted, but the filling device supplies liquid contents from a tank to a container. A supply pipe is provided for this purpose, and a filling valve and an electromagnetic flow meter are arranged in the middle of the supply pipe. In FIG. 1, 10 is a supply pipe, 20 is an electromagnetic flow meter, 30 is a conversion unit, 40 is a counter, 50 is a control unit, 60 is an operation unit, and 70 is a filling valve.

The electromagnetic flow meter 20 outputs an electromotive force proportional to the flow rate (flow velocity) of the liquid (liquid content) flowing through the supply pipe 10. The converter 30 converts the electromotive force from the electromagnetic flow meter 20 into a digital value, samples the digitally converted electromotive force at a constant cycle, and calculates the frequency of a square pulse to be output. The counter 40 counts the pulses output from the converter 30 and outputs a count-up signal when the counted value reaches a preset value. The control unit 50 is a sequence controller or the like including a CPU, and outputs a control signal in response to a counter-up signal from the counter 40. The operation unit 60 is formed of, for example, an electromagnetic valve, and closes the filling valve 70 when receiving a control signal from the control unit 50.

Next, the filling method of the present embodiment will be specifically described. When the filling valve 70 is opened to supply the liquid content to the container, a predetermined flow rate q (ml / se
The liquid content of c) flows, and the electromagnetic flow meter 20 outputs an electromotive force E (V) proportional to the flow rate q. The conversion unit 30 is configured based on the relationship between the flow rate and the pulse set in advance.
The frequency of the square pulse to be output is determined from the detected electromotive force E. At this time, a certain sampling rate is determined, and an operation for obtaining the pulse frequency f from the digitally converted electromotive force E is performed at certain intervals based on the determined sampling rate.

Here, a certain (optimum) sampling rate is obtained as follows. In order to find the optimum sampling rate, a simulation by calculation was performed. Assuming the flow rise of a sine curve as shown in FIG. 3, the rise time t _p = 400 msec. When the frequency analysis of the waveform at the rising portion was performed by Fourier transform using a Hanning window, the results shown in the following table were obtained.

[0026]

[Table 1] ──────────────────────────────── Order Frequency Hz Amplitude intensity Intensity ratio% Cumulative intensity ratio% ── １ 1 0.312 47.037 28.9 928.99 2 0.625 39.093 24.09 53.08 3 0.937 28.430 17.52 70.60 4 1.249 17.916 11.04 81.64 5 1.562 10.073 6.21 87.85 6 1.874 6 .130 3.78 91.63 7 2.186 4.624 2.85 94.48 8 2.499 3.310 2.04 96.52 9 2.811 1.921 1.18 97.70 10 3. 123 0.962 0.59 98.29 11 3.436 0.533 0.3 98.62 12 3.748 0.220 0.14 98.76 13 4.061 0.105 0.07 98.82 14 4.373 0.256 0.16 98.98 15 4.685 0.253 0 .16 99.14 ::::::::::::: Total-212 .143--────────────────────────────────

The intensity ratio in the table is the sum of the amplitude intensities.
143 is calculated as 100%, and the right column is the accumulation of this value. If the respective frequency components obtained as a result of the Fourier transform are recombined, the original waveform can be obtained. However, the frequency component of the order whose cumulative intensity ratio exceeds 99%, in the above calculation example, the frequency of the 15th order 4.7 Hz It was found that the original waveform can be reproduced with an accuracy of 0.5% or less by taking the components.
Therefore, a frequency of an order whose cumulative intensity ratio obtained by this method exceeds 99% is called a rising frequency.

FIG. 2 shows, for various sampling rates, how much the deviation from the actual flow rate varies when the waveform having the rising frequency of 4.7 Hz is input with a phase difference. The vertical axis of the graph in FIG. 2 indicates the difference between the maximum value and the minimum value of the deviation, and the horizontal axis indicates the ratio of the sampling rate to the rising frequency of 4.7 Hz. As is clear from the figure, the variation in the deviation is large in a region where the ratio between the sampling rate and the frequency component of the rising waveform is approximately 2 or less. In order to fill the content liquid with sufficiently practical filling accuracy, it is desirable to select the sampling rate so that the ratio of the sampling rate to the frequency component of the rising waveform is at least 2 or more, preferably 4 or more. I understand.

From the rising waveform of the flow rate measured during the actual filling test, the rising frequency defined above was found to be about 10 to 20 Hz. Therefore, in order to perform filling with practical accuracy, it is necessary that the sampling rate be higher than at least 10 × 2 = 20 Hz.

On the other hand, in the electromagnetic flow meter, an AC excitation method is generally used to separate noise and improve accuracy. However, when the polarity of the excitation current changes to positive or negative,
Has a finite time for the magnetic flux density to reach a steady state value,
If the excitation waveform is a square wave in order to improve the rise of the magnetic flux density, noise is generated at the rise and fall portions. Due to such a problem, the upper limit of the sampling rate is about 100 Hz.

Taking these into consideration, the applicable sampling rate range is 20 to 100 Hz.

Next, considering the flow velocity of the liquid content flowing through the supply pipe 10, the electromagnetic flow meter has a limitation on the flow velocity v of the fluid to be measured due to its measurement principle.
The measurement itself can be performed at a flow rate of 0 m / s or more.However, if the flow rate is small, the measurement error increases. To obtain the filling accuracy applicable to this filling method, the flow rate v of the liquid content must be It has been found that a flow rate of 0.3 m / s or more is required, preferably a flow velocity of 0.5 m / s or more.

On the other hand, to increase the flow velocity, it is sufficient to reduce the diameter of the pipe. However, if the flow velocity is too high, the pressure loss due to pipe friction increases, which is not practical. The loss head due to pipe friction is h ₁ = λ (l / dv ² / 2g) [m]
Is required. Here, λ is a pipe friction coefficient, l is a pipe length [m], d is a pipe inner diameter [m], and g is a gravitational acceleration = 9.80.
665 [m / s ² ], and when the flow is laminar, λ = 64 /
Re (where Re is Reynolds number).

Further, the flow rate q of the liquid content per unit time at the time of filling is q = about 150 to 200 ml / s in many currently used filling apparatuses. Since the filling is performed too quickly, the foaming becomes excessive and overflows from the container, and it is difficult to remove oxygen from the head space. Therefore, it is desirable that q is at most 250 ml / s at the most, and q is at most 200 ml / s at the time of filling a liquid such as carbonated beverage and beer which is liable to foam.

Since the flow rate is determined by the cross-sectional area and flow velocity of the pipe through which the liquid flows, if the inner diameter of the pipe is d, q = (πd ² /
4) d = 2√ (q / πv) is obtained from the relationship of v. From these equations, the loss head per unit length of the pipeline is h ₁ / l = (8πν / gq) · v ² (where ν is the kinematic viscosity of the liquid: approximately ν = 1.0 × 10 ⁻⁶ [ m ² / s])
Becomes

For example, if q = 250 ml / s and v = 0.3
The loss head per unit length of the pipeline at m / s is h ₁
/L=｛(8π·1.0×10 ⁻⁶ ) / (9.88065)
× 250 × 10 ⁻⁶ )｝ · 0.3 ² ≒ 0.00092, but when v = 1.5 m / s, h ₁ / l = ｛(8π
・ 1.0 × 10 ⁻⁶ ) / (9.80665 × 250 × 10)
⁻⁶ )｝ · 1.5 ² ≒ 0.023, and the loss head increases in proportion to the square of the flow velocity v. Therefore, there is a limit to increasing the flow rate by reducing the pipe diameter, and it is considered that v = 1.2 m / s or less is a practical range. As a result, the applicable flow rate range is 0.3 to 1.2.
m / s.

As is apparent from the above description, the filling method according to the present embodiment sets the sampling rate for the calculation at the time of pulse conversion in the range of about 20 to 100 Hz and sets the flow rate of the liquid content to about 0.3 to 100 Hz. By setting the speed to 1.2 m / s, accurate filling can be performed.

The present invention is not limited to the above embodiments, but includes various modifications within the scope of the invention. For example, instead of performing digital conversion in the conversion unit and performing an operation of converting the pulse into a pulse having a frequency proportional to the detected electromotive force, the electromotive force obtained by digital conversion at a certain interval is directly integrated, and the integrated value is calculated. A signal for closing the filling valve may be output to the operation unit when the value exceeds a preset value.

[0039]

As described above, the first aspect of the present invention is as follows.
According to the liquid content filling method described above, the sampling rate can be made sufficiently high to accurately measure the flow rate signal whose rise changes relatively sharply, and accurate filling can be performed.

According to the second aspect of the present invention, the conversion into the electric signal is converted into a pulse signal, and the integration is performed as the counting of the pulse signal. Therefore, the signal from the electromagnetic flow meter is converted into the pulse signal. After the conversion, arithmetic processing and the like can be performed easily and quickly.

Further, according to the third aspect of the present invention, since the sampling rate of the calculation at the time of conversion into the pulse signal is set to about 20 to 100 Hz, the sampling rate is sufficiently high for a rapidly changing flow rate signal. Thus, the flow rate at the rising portion can be accurately measured.

According to a fourth aspect of the present invention, the flow rate of the liquid content is about 0.3 to 1.2 m / s, so that accurate and stable measurement results can be obtained without being adversely affected by the flow rate. Can be obtained.

[Brief description of the drawings]

FIG. 1 shows a block diagram of an apparatus for implementing a method according to an embodiment of the present invention.

FIG. 2 is a graph obtained by calculating a change in filling accuracy when a sampling rate is changed while a rising frequency is fixed.

FIG. 3 is a graph showing a rising curve of a flow rate used for prediction of filling accuracy.

FIG. 4 is a graph for explaining a cause of a decrease in filling accuracy due to a variation in a phase difference at the time of rising of a flow rate.

FIG. 5 is a graph for explaining a cause of a decrease in filling accuracy due to a variation in a rising speed when a flow rate rises.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Supply pipe 20 Electromagnetic flow meter 30 Conversion part 40 Counter 50 Control part 60 Operation part 70 Filling valve

Claims (4)

(57) [Claims] When a liquid content is supplied and filled into a container at a predetermined flow rate, a flow rate of the liquid content is measured by an electromagnetic flow meter, and an output proportional to a flow signal from the electromagnetic flow meter is output. It is calculated at a predetermined sampling rate and converted into an electric signal, and the converted electric signal is integrated. When the integrated value reaches a preset value,
A method for filling a liquid content in which a supply of liquid content is stopped by closing a filling valve, wherein a sampling rate of an operation when converting an output proportional to the flow rate into an electric signal is determined by calculating a sampling rate of the flow rate signal to be measured. A method for filling a liquid content, wherein the speed is higher than a rising speed. 2. The method according to claim 1, wherein the conversion into the electric signal is a conversion into a pulse signal, and the integration is a counting of the pulse signal. 3. The method according to claim 2, wherein the sampling rate of the calculation at the time of conversion into the pulse signal is about 20 to 100 Hz. 4. The method according to claim 1, wherein the flow rate of the liquid content is about 0.3-1.
The method for filling a liquid content according to claim 1, 2 or 3, wherein the liquid content is 2 m / s.