JPH0571799B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a flow rate measurement method for indirectly measuring the flow rate of a liquid from the rotational speed of a pump without using a flow meter inserted in the middle of the flow path. The device can be used particularly in fields such as food, cosmetics, or pharmaceuticals, which handle perishable products, products that easily undergo chemical changes, or products with high viscosity.

(Prior art) The conventional method of measuring the flow rate of a liquid is to convert the flow into rotational force using, for example, an oval gear type flow meter inserted in the middle of the flow path, and convert this rotational force into an electrical signal using an appropriate method. is converting. In addition, as a method of measuring the flow rate from the outside of the pipe line forming the liquid flow path,
Methods using ultrasonic flowmeters or electromagnetic flowmeters are also known.

(Problems to be Solved by the Invention) With the method of interposing a flow meter in the liquid flow path as described above, if the liquid is a high viscosity liquid or a liquid containing solids, measurement may become impossible or accurate measurement may not be possible. I can't expect that. Furthermore, since the internal structure of a flowmeter is complex, liquids tend to adhere to the inside of the flowmeter, and when dealing with liquids such as food or medicine, there is a risk of decay, compositional changes, or sanitary changes in the adhering residue inside the flowmeter. The above problem arises.

In addition, methods using ultrasonic flowmeters do not cause the above-mentioned sanitary problems, but the liquids that can be measured are limited, and these flowmeters are expensive and complicated to use. It has some drawbacks.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention links an oscillator that generates rotation pulses to a positive displacement rotary pump that pumps the fluid to be measured, and outputs pulses from the rotation pulse oscillator. is frequency-divided by a frequency dividing means having a frequency division ratio obtained by dividing the discharge flow rate value per rotation of the pump by a constant value, and the frequency division pulses are counted to match the pump discharge flow rate. This paper proposes a flow rate measurement method that is characterized by obtaining a count value.

Further, the present invention provides a flow rate measuring device suitable for carrying out the method of the present invention, which includes a rotary pulse oscillator that is linked to a positive displacement rotary pump that pumps the fluid to be measured, and a frequency-divided output pulse of the rotary pulse oscillator. and an input input to the discharge flow rate per rotation of the pump in order to set the frequency division ratio of the frequency division means to a value obtained by dividing the discharge flow rate per rotation of the pump by a constant value. and a counting means for counting frequency-divided pulses frequency-divided by the frequency-dividing means, and configured such that the count value of the frequency-divided pulses matches the discharge flow rate of the pump. Suggest a device.

(Operations and Effects of the Invention) In the above-described flow rate measurement method according to the present invention, the positive displacement rotary pump that pumps the fluid to be measured has a higher volumetric efficiency than other pumps, for example, a spiral rotary pump body. Since the rotation speed of the pump and the discharge amount are proportional to each other, the discharge flow rate can be determined from the rotation speed of the pump. Therefore, the count value per unit time of pulses output from a rotary pulse oscillator linked to such a positive displacement rotary pump in proportion to the rotation speed of the pump is proportional to the discharge flow rate per unit time. .

However, in the method of the present invention, the output pulses are not counted directly, but the frequency-divided pulses obtained by dividing the frequency are counted, but generally, as in pulse frequency division, the repetition frequency of the pulse is calculated by an integer. Instead of dividing it by a factor of 1/2n, the dividing ratio is such that the denominator (divisor) is constant and the numerator (dividend) is equivalent to the discharge flow rate per revolution of the pump, that is, the discharge flow rate per revolution of the pump. Since the frequency of the output pulse of the rotary pulse oscillator is divided by the frequency division ratio obtained by dividing the value by a constant value, and this frequency-divided pulse is counted,
The count value of the frequency-divided pulse directly becomes the discharge flow rate value. For example, if a rotary pulse oscillator that outputs 100 pulses in one revolution of the pump is used, and the discharge flow rate during one revolution of the pump is 0.1, the divisor is 100 and the dividend is the discharge flow rate value. 0.1 of
If the output pulse of the pulse oscillator is divided by the frequency division ratio set to (0.1/100 = 1/100), the number of divided pulses per revolution of the pump will be 100 x 1/1000.
= 0.1, and 1 frequency-divided pulse is obtained with 10 pump rotations (accumulated flow rate 1), so this frequency-divided pulse becomes a flow rate pulse with a weight of 1 pulse = 1, and its count value matches the accumulated flow rate. . If the discharge flow rate per rotation of the pump is set to 100 in cc units and the integrated flow rate is measured in units, the divisor may be set to 100×1000 and the dividend may be the discharge flow rate value in cc units.

In other words, if the output pulse of the rotary pulse oscillator is simply divided by an integer, the frequency-divided pulse will not match the flow rate, but by dividing the frequency in the manner described above, the pulse It can be converted into a flow rate pulse by giving a weight of Therefore, if the frequency-divided pulses are integrated and counted, the integrated count value corresponds to the integrated flow rate value, and by counting the frequency-divided pulses within an extremely short set time, the count value corresponds to the instantaneous flow rate value. It turns out.

As described above, according to the flow rate measurement method of the present invention, the flow rate is measured indirectly from the rotational speed of the pump, so that the numerous disadvantages caused by interposing a flow meter in the middle of the flow path can be completely eliminated. However,
In particular, with the method of the present invention, the flow rate value can be obtained by simply counting the frequency-divided flow pulses, so the output pulses of the rotary pulse oscillator linked to the pump can be directly counted, and the counted value can be used as the flow rate value. Compared to the case of performing calculations for conversion, there is no need to use a calculation function such as a microcomputer, and it can be performed easily and inexpensively using simple means.
In addition, it can be used as a flow meter that outputs one pulse per unit flow rate and is exactly the same as a conventional flow meter inserted in a flow path, so it can be combined with various external devices in the same way as a conventional flow meter. It is easy to perform and has excellent versatility.

Furthermore, according to the measuring device of the present invention described above,
The frequency dividing ratio of the frequency dividing means for frequency dividing the output pulse of the rotary pulse oscillator interlocked with the pump is set to 1 of the pump.
In order to obtain a value obtained by dividing the discharge flow rate per rotation by a constant value, input means for inputting the discharge flow rate per rotation of the pump is provided.
It can be easily adapted to any liquid pumping device having various discharge flow rates per rotation, and accurate flow rate measurement (integrated flow rate or instantaneous flow rate) is possible.

(Example) An example of the measuring device according to the present invention and an example of the measuring method of the present invention performed using the device will be described below based on the attached illustrative drawings.

In FIG. 1, reference numeral 1 denotes a positive displacement rotary pump, to which a driving motor 2 and a rotary pulse oscillator 3 are operatively connected. Therefore, by rotationally driving the pump 1 with the motor 2, liquid is sucked through the suction pipe 1a and discharged from the discharge pipe 1b at a flow rate proportional to the rotation speed of the pump 1. The output pulses of the rotation pulse oscillator 3 are counted by a rotation number counter 5 within the gate time of the gate circuit 4, and the counted value is displayed on a rotation number display device 6 consisting of a plurality of 7-segment LEDs. Here, if the rotary pulse oscillator 3 outputs 100 pulses per one rotation of the pump 1, and the rotation speed of the pump 1 is 300 rpm, the number of pulses per second is 300×100÷60. = 500, and in order to directly display the rotation speed in rpm on the display device 6, 300÷500=
0.6, so if a gate time of 0.6 seconds is set in the gate circuit 4, the count value on the counter 5 will be 500 x 0.6 = 300, and the rotation speed of the pump 1 will be directly displayed in rpm on the display device 6. It can be displayed. In other words, the rotation speed of pump 1 is n (rpm)
The count value of the counter 5 is 100×n÷60×0.6=n, and the rotational speed n (rpm) of the pump 1 can be directly read from the rotational speed display device 6.

Further, the output pulse of the rotary pulse oscillator 3 is frequency-divided by a frequency divider 7 whose frequency division ratio is determined by the contents of a register 13, which will be described later. The instantaneous flow rate is counted by an instantaneous flow rate counter 9, and the counted value is displayed by an instantaneous flow rate display device 10. The keyboard 11 displays the discharge flow rate value Q per revolution of the pump 1.
(cc/rev) and integrated flow rate preset value P()
This is for inputting and setting, and by switching the changeover switch 12, the two registers 1
3 and 14 can be selected to write the set value, and the contents of each register 13 and 14 can be selectively displayed on the set value display device 15 by the changeover switch 12.
Displayed by

Discharge flow rate per revolution of pump 1 Q (cc/
rev) is determined in advance by conducting a test under conditions close to actual usage conditions, and the numerical value is entered using the keyboard 11 and recorded in the register 13. The frequency division ratio of the frequency divider 7 is configured to be a value obtained by dividing the discharge flow rate value Q recorded by the register 13 by 1000 (Q/1000). Here, if the discharge flow rate Q per rotation of the pump 1 is 100c.c., the frequency division ratio of the frequency divider 7 is 100/1000=1/10
Therefore, the number of divided pulses per second is 500÷10
= 50, and the instantaneous flow rate per rotation of pump 1 is 100 x 300 ÷ 1000 = 30 (/min),
Directly display the instantaneous flow rate with the instantaneous flow rate display device 10.
To display in min, 30÷60=0.6, so
If a gate time of 0.6 seconds is set in the gate circuit 8, the count value in the instantaneous flow counter 9 will be 50×
0.6=30, and the instantaneous discharge flow rate of the pump 1 can be directly displayed in /min by the instantaneous flow rate display device 10. In other words, the rotation speed n (rmp)
If the instantaneous discharge flow rate of pump 1 at the time is F (/min), then F = Q × n ÷ 1000, while the count value of instant flow counter 9 is n ÷ 60 × 100 × Q ÷ 1000 × 0.6 = Q ×n÷1000=F, and the instantaneous discharge flow rate F (/min) of the pump 1 can be directly read using the instantaneous flow rate display device 10.

The output of the frequency divider 7 (frequency division pulse) is further divided by another frequency divider 16, and then counted by the cumulative flow counter 17, and the counted value is displayed on the cumulative flow rate display device 18. is displayed. Here, since the pump 1 discharges 100 c.c. per revolution, in order to convert the output pulse of the rotary pulse oscillator 3 into a unit flow rate pulse, it is divided into 0.1 pulses per revolution of the pump 1. Just go around it,
Output pulse of the rotary pulse oscillator 3 (pump 1
100 pulses per revolution) is 0.1÷100=1/1000
You can divide the frequency into The output pulse of the rotary pulse oscillator 3 has already been divided into 100/1000 by the frequency divider 7 for instantaneous flow rate measurement.
If the frequency division ratio of 6 is set to 1/100, the output of this frequency divider 16 will be 0.1 pulse (equivalent to 0.1) per 1 rotation of pump 1, and 1 pulse will be output for 10 rotations of pump 1.
A pulse (equivalent to 1) is output. Therefore, the count value of the counter 17 that counts the output pulses of the frequency divider 16 becomes the cumulative flow value of the minimum digit 1. In other words, the cumulative flow rate S when the pump 1 rotates N times
() is S = Q × N ÷ 1000, and on the other hand, the count value of the cumulative flow counter 17 is 100 × N × Q ÷ 1000 ÷ 100 = Q × N ÷ 1000 = S. The cumulative flow rate S( ) of the pump 1 can be directly read by the cumulative flow rate display device 18 that displays numerical values.

The comparator circuit 19 compares the count value S() of the cumulative flow rate counter 17 with the preset value P() of the cumulative flow rate inputted from the keyboard 11 and stored in the register 14, and determines that the counted value S is equal to the preset value P.
When this happens, the control relay 20 is operated.
By operating this relay 20, a buzzer for warning can be sounded or rotation of the motor 2 can be stopped.

As can be understood from the above explanation, when counting the flow rate, Q (discharge flow rate value per revolution of the pump 1), which is the numerator of the frequency division ratio in the frequency divider 7, plays an important role in accuracy. . This Q is determined in advance through testing as described above, and if this value is accurate, the values of the counted flow rates (instantaneous flow rate and integrated flow rate) will also be accurate. Therefore, find the value of Q according to various conditions during actual use,
Each time the usage conditions change, enter the value of Q on the keyboard 1.
It is desirable to reset the settings to 1. However, if particularly high accuracy is not desired, Q may be obtained from a calculated value based on the design of the pump 1. This Q value can be input easily using a keyboard, so
Even when replacing the pump 1 or measuring the flow rate of a different pump device, the present invention can be easily applied.

In FIG. 2, reference numeral 21 is a power switch, 22 is an emergency stop switch, and 23 is a switch that automatically turns off the motor 2 when the relay 20 is activated.
Reference numeral 24 is a switch for starting the motor 2, which selects whether or not to stop the motor.

In this embodiment, a rotary pulse oscillator 3 that outputs 100 pulses per rotation of the pump was used, but the number of pulses per rotation of the pump is not limited, and may vary depending on the number of pulses. , it is sufficient to set the frequency division ratio when measuring the integrated flow rate and the gate time when measuring the instantaneous flow rate. Further, the input unit of the discharge flow rate value per revolution of the pump and the display unit of each display device 6, 10, 18 are not limited to those of the above embodiment, and the frequency division ratio may be set according to these units. Further, in the embodiment, the keyboard 11 and the register 13 are used as input means, but a digital switch having an appropriate number of digits may be used instead.

Further, in the embodiment, the pump rotation speed, the instantaneous discharge flow rate, and the cumulative flow rate are measured and displayed, but the configuration may be such that at least one of the instantaneous discharge flow rate and the cumulative flow rate can be measured.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electric circuit of the measuring device, and FIG. 2 is a front view showing the operation panel of the same device. 1... Displacement rotary pump, 3... Rotating pulse oscillator, 4, 8... Gate circuit, 5... Rotation number counter, 6... Rotation number display device, 7, 16... Frequency divider, 9... Instantaneous Flow rate counter, 10... Instantaneous flow rate display device, 11... Keyboard (input means), 1
3, 14...Register (input means), 15...Setting value display device, 17...Accumulated flow counter, 18...
...Accumulated flow rate display device, 19...Comparison circuit, 25...
…relay.

Claims (1)

[Claims] 1. A rotary pulse oscillator is linked to a positive displacement rotary pump that pumps the fluid to be measured, and the output pulse of the rotary pulse oscillator is calculated by dividing the discharge flow rate per revolution of the pump by a constant value. A method for measuring a flow rate, characterized in that the frequency is divided by a frequency division means having the obtained frequency division ratio, and the frequency division pulses are counted to obtain a counted value that matches the discharge flow rate of the pump. 2. The flow rate measurement method according to claim 1, wherein a count value that matches the instantaneous discharge flow rate of the pump is obtained by counting the frequency-divided pulses within a set time. 3. A rotary pulse oscillator that is linked to a positive displacement rotary pump that pumps the fluid to be measured, a frequency dividing means that divides the output pulse of the rotary pulse oscillator, and a frequency division ratio of this frequency dividing means that is set to one revolution of the pump. an input means for inputting a discharge flow rate value per revolution of the pump, and a counter for counting frequency-divided pulses divided by the frequency dividing means, in order to obtain a value obtained by dividing the per-turn discharge flow rate value by a constant value; and a flow rate counter configured such that the count value of the frequency-divided pulse coincides with the discharge flow rate of the pump. 4. The counting means comprises a gate circuit and a counter so that the count value of the frequency-divided pulses within a set time matches the instantaneous discharge flow rate of the pump. The flow rate measuring device described in .