JP3494743B2 - Flowmeter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter for measuring a flow rate of a fluid and displaying the flow rate on a display unit, and more specifically, to prevent flickering of a display value due to pulsation of a flow. It relates to a flow meter.

[0002]

2. Description of the Related Art Conventionally, as a flow meter for measuring and displaying a flow rate of a fluid such as water or another heat medium, a pulse corresponding to the flow rate is generated, and an instantaneous flow rate value obtained by calculation after the pulse measurement. Is generally used, but the flow generally has a pulsation, and a pulse is generated thereby, so that the displayed value flickers. Therefore, the flicker of the displayed value is suppressed as much as possible by displaying a moving average of the previous measured value and the present measured value.

[0003]

In the above-mentioned conventional flowmeter, in order to prevent flickering of the displayed value caused by the pulsation of the flow, the moving average of the previous measured value and the present measured value is taken and displayed on the display unit. in relationship, it takes time display value at the rise or fall of the display even if flicker prevent flow is the flow value of the real, without good responsiveness during the rise or fall, in particular , even if there is no flow there is a problem that Rana physicians such to 0 display value immediately.

[0004] Accordingly, the present invention has been made in view of the conventional problems described above, the flow Re has disappeared along with the prevention of display flicker
Has been with the purpose to provide a flow meter that was so that can sometimes to zero quickly the flow rate display.

[0005]

[0006]

[0007]

Flowmeter was made by the present invention for achieving the above Symbol purpose Means for Solving the Problems], as shown in the basic diagram of Fig. 1, the period corresponding to the flow rate of the fluid flowing through the flow path A sensor unit 40 that generates a signal pulse, an instantaneous flow rate measuring unit 30-1 that measures the instantaneous flow rate by counting the pulses generated by the sensor unit for a certain period of time, and an instantaneous value measured by the instantaneous flow rate measuring unit. a display unit 26 for displaying the flow rate, the
Fluid flow based on the current measurement results by the instantaneous flow rate measurement unit
This time flow detection means 30-2 for detecting the presence or absence of
There is a flow when the flow detection means detects the presence of a fluid flow.
That is, the current flow detection means detects no fluid flow.
Flow display means for displaying that there is no flow
In flow meter and a 26 g, the previous flow detector 30-3 for detecting the presence or absence of fluid flow through previous measurement results by pre Symbol instantaneous flow rate measurement unit, vital detects the presence the current flow detection means fluid flow The moving average value of the instantaneous flow rate measured by the instantaneous flow rate measurement unit was displayed on the display unit when the previous flow detection unit detected the presence of the fluid flow, and the current flow detection unit detected the absence of the fluid flow. Display control means 3 for displaying 0 on the display means
It is characterized by including 0-4.

[0008] To achieve the above Symbol purpose the present invention by made flow meter, as shown in the basic diagram of Fig. 1, a sensor for generating a signal pulse period corresponding to the flow rate of the fluid flowing through the flow path A unit 40, an instantaneous flow rate measuring unit 30-1 that measures the instantaneous flow rate by counting the pulses generated by the sensor unit for a certain period of time, and a display unit that displays the instantaneous flow rate measured by the instantaneous flow rate measuring unit. And the instantaneous flow rate measurement unit
The presence or absence of fluid flow is now detected based on the current measurement results.
The circulation flow detection means 30-2 and the current flow detection means are fluids.
If a flow is detected, it means that there is a flow.
There is no flow when the detection means detects no fluid flow.
And a flow display means 26g for displaying preparative respectively, before
The display means displays the instantaneous flow rate by switching the mode.
Instead, the instantaneous flow rate measured by the instantaneous flow rate measurement unit is
The integrated flow rate value obtained by sequentially adding is displayed.
In Tei Ru flowmeter, the previous flow detector 30-3 for detecting the presence or absence of fluid flow through previous measurement results by pre Symbol instantaneous flow rate measurement unit, the is now flow detection means detects the presence of fluid flow and the previous a moving average value of the instantaneous flow rate the instantaneous flow rate measurement unit measures when the flow detecting means is detecting the presence of fluid flow is displayed on said display means, moreover before
Note that when the flow detector detects no fluid flow this time,
And a display control means 30-4 for displaying 0 on the display means.

[0009]

[0010]

[Action] In the configuration for the above purpose, the instantaneous flow rate measurement unit 30-1 counts a predetermined time a signal pulse of the period corresponding to the flow rate of the fluid flowing through the flow channel sensor unit 40 is generated at regular intervals instantaneous Measure the flow rate. The display means 26 displays the instantaneous flow rate measured by the instantaneous flow rate measuring unit. The display control means 30-4 measures this time by the instantaneous flow rate measuring unit.
The previous flow detecting means 30-2, which detects the presence or absence of fluid flow based on the result , detects the presence of fluid flow, and detects the presence or absence of fluid flow based on the previous measurement result by the instantaneous flow rate measuring unit. Since the moving average value of the instantaneous flow rate measured by the instantaneous flow rate measuring unit is displayed on the display means when 3 detects the presence of the fluid flow, it is possible to prevent the displayed value from flickering due to the pulsation of the flow, and moreover, the flow detection this time. When the means detects the absence of fluid flow, 0 is displayed on the display means irrespective of what kind of flow was there before, so that flicker on the display can be prevented and the flow rate becomes 0. The actual flow rate value displayed without taking time
It can be set to 0.

[0011] In addition, flow display means, the mode switching
The display means displays either the integrated flow rate value or the instantaneous flow rate.
Even if it is, it is effective to directly notify the presence or absence of fluid flow
However, whether the flow of fluid is displayed on the display means
It is especially effective when displaying the integrated flow rate value.
is there. Moreover, the instantaneous flow rate is displayed on the display by switching the mode.
Is displayed, the current flow detection means is
What kind of flow was there before it was detected
0 is displayed on the display regardless of whether or not
Then, the flicker on the display was prevented and the flow rate became 0.
The actual display value can be set to 0 without taking time.
It is like this.

[0012]

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a view showing the structure of a flowmeter according to the present invention, (a) is a top view showing a display and operation panel surface,
(B) is sectional drawing which shows the internal structure of a flowmeter, (c) is a side view which fractures | ruptures a part and shows. In the figure, a flow meter comprises a measuring unit main body 1 connected in the middle of a flow path through which a fluid whose flow rate is to be measured flows, and 90 ° above the measuring unit main body 1.
The measurement display unit 2 is attached so as to be able to position each of them.

As shown in the enlarged sectional view of FIG. 3, the measuring portion main body 1 is provided with a flow passage 1a having a circular cross section which penetrates the inside thereof, and a flat portion 1b is formed on a part of the outer wall. The flat portion 1b has a first hole 1b ₁ and a second hole 1b ₁ which communicate with the flow path 1a.
1b ₂ of the first hole 1b ₂ are formed at a predetermined interval.
b ₁ is upstream of the flow path 1a. 11 is the flow path 1a
Is a vortex generator arranged inside, and has, for example, a prismatic outer shape, and is composed of a shaft portion 11a and a head portion 11b that fits into the first hole 1b ₁ and engages with the flat portion 1b. the shaft portion 11a is inserted into the first hole 1b ₁ passage 1a.
A temperature sensing element 12 is embedded in the shaft portion 11a of the vortex generator 11, detects the temperature of the fluid flowing in the flow path 1a, generates a temperature detection signal, and guides it to the outside via a lead wire 12a. And supplies it to the measurement display unit 2.

Reference numeral 13 denotes a vortex detector composed of an elastic sheath 13a having an insulating property and a piezoelectric element 13b. In the elastic sheath 13a, a pressure-receiving wing piece 13a ₁ is flowed through a second hole 1b ₂ . It is inserted in 1a. Elastic sheath 13a is molded of a resilient synthetic resin, the pressure receiving wing 13a ₁ is overhanging toward the upstream side and the downstream side of the flow path 1a, its head 13a ₂ is fitted into the second hole 1b ₂ With flat part 1b
Is engaged with. The piezoelectric element 13b is embedded in the shaft portion of the elastic sheath 13a, that is, the pressure-receiving blade piece 13a ₁ and the head portion 13a ₂ by a thermosetting elastic epoxy resin having an insulating property, and the detection signal is supplied by the lead wire 13b _1. It is led out to the outside and supplied to the measurement display unit 2.

A means such as a screw is attached to the flat portion 1b.
Therefore, the lid 13c is attached, and the first lid 13c is
Hole 1b₁Corresponding to the first screw hole 13c₁And the second
Hole 1b₂Corresponding to the second screw hole 13c₂Is provided
ing. First screw hole 13c ₁The first ring 13d₁
Are screwed together to attach the head 11b to the first packing 13e.₁Through
The flat portion 1b and the second screw hole 13c.₂
The second ring 13d ₂Is screwed to the head 13a₁The first
1 packing 13e₂To the flat part 1b through
Prevents fluid leakage.

In the above structure, a Karman vortex is generated by the vortex generator 11 in the fluid flowing through the flow path 1a of the metering unit main body 1, and this Karman vortex moves toward the vortex detector 13 to cause the elastic sheath 13a. Since it alternately passes on both sides of the pressure-receiving wing piece 13a ₁ , the piezoelectric element 1
A strain force acts on 3b to generate an electric charge. Therefore, the charge generated in the piezoelectric element 13b is used as a detection signal in the lead wire 1
3b ₁ is taken out, and this is taken out by the measurement display unit 2 which will be described later.
The flow rate can be measured by performing signal processing by the circuit.

Further, the temperature detection signal of the temperature sensitive element 12 embedded in the vortex generator 11 can be used as a signal for knowing the fluid density, the fluid viscosity, etc., and the temperature detection signal and the measured value of the flow rate can be used. You can get the amount of heat, but
This temperature detection signal is also used to display the temperature.

The operating principle of the Karman vortex flowmeter will be described in more detail with reference to FIG. 4. An obstacle 11 as a vortex generator having a width d in the flow, and a thin plate 13 as a vortex detector are placed thereafter. Then, vortices U which are regularly and alternately generated on both sides of the obstacle apply a small force to the thin plate 13 to vibrate it. Thin plate 1
When the frequency of 3 is f, the flow velocity is V, and the width of the obstacle 11 is d, a relationship of f = St × (V / d) is established between them. Note that St is a Strouhal constant, which is a constant determined by the shape of the vortex generator 11, and as shown in FIG. 5, has a constant value (about 0.2) in a wide range of Reynolds number of 3 × 10 ³ to 10 ^5. ) Is maintained, measurement with good linearity can be performed. Since St and d are constant values, the flow velocity and further the flow rate can be measured by detecting the vibration frequency with the piezoelectric element 13b of the vortex detector 13 installed at the optimum position behind the vortex generator. This Karman vortex flow type has a simple structure with no sliding parts and has excellent reliability and durability.In addition, the vortex generator and vortex detector are included in the fluid flow path. Since the throttle of is small, the pressure loss is small.

The measurement display unit 2 includes a case 23 composed of a lower case 21 and an upper case 22, which are butted against each other via a waterproof packing, a printed circuit board 24 and a power supply battery 25 housed in the case 23, and an upper case. A hollow rotary shaft 3 fixed on the weighing unit main body 1 is provided with a waterproof packing in a hole 21a formed in the bottom of the lower case 21 by a liquid crystal display 26 and a mode selection button 27 arranged on the upper surface of the lower case 22. It is rotatably fitted to the measuring unit main body 1 so that it can be positioned at 90 ° intervals. The lead wires 12a and 13b ₁ are led to an electric circuit formed on the printed board 24 through the hollow portion of the rotary shaft 3.

The upper case 22 of the case 23 is the lower case 21.
A screw 28 is attached so as to be openable and closable so that it can be opened when various setting operations are performed on the electric circuit or when the battery 25 is replaced.

The display unit 26 arranged on the upper surface of the upper case 21 of the measurement display unit 2 has a small 4-digit numerical display unit 26a and a large 4-digit numerical display unit 26b arranged from the lower left side, and the large 4-digit numerical display unit 26b. A unit display section is arranged on the further right side of the numeral display section 26b. The unit display area is "m ³ /
An “h” segment display 26c and an “L / min” segment display 26d are arranged. Then, the "ECO" segment display 26 is displayed on the upper stage of the small 4-digit number display portion 26a.
e and the "BAT" segment display 26f are arranged on the upper stage of the large 4-digit number display section 26b, and four bar segment displays 26g are arranged in a line corresponding to each digit.

The most significant digit of the small 4-digit numerical display section 26a functions as a status display section showing the current display status and the current display mode, and the four bar displays 26g display the flow status by blinking rotation. Works as a display. Note that FIG. 2 shows a state in which all of the displays 26a to 26g are lit, and in practice, these are selectively lit and displayed according to the situation.

The circuit configuration of the flow meter having the above-described configuration is shown in the block diagram of FIG. 6, and in FIG.
Reference numeral 0 is a control unit composed of a microcomputer that operates according to a predetermined control program, and a central processing unit (CPU) 30 'and an RO that stores the control program.
A RAM 3 having an M30a and a data area for storing various data and a work area used for various processes
0b and built-in.

To the input port I ₁ of the control unit 30, a mode changeover switch 27a is connected as a manual operation means composed of a momentary switch which is turned on by pressing a mode selection button 27 arranged on the upper surface of the upper case 22. ing. In addition, the piezoelectric element 13 is connected to the input port I _2.
The output of a waveform shaping circuit 32 that outputs a pulse signal by waveform shaping the output signal of the charge amplification circuit 31 that amplifies the charge signal generated when b receives the distortion force is connected. The charge amplification circuit 31 and the waveform shaping circuit 32 are the analog switches 4
The piezoelectric element 13b, the charge amplification circuit 31, and the waveform shaping circuit 32 operate only when the power source V _CC is supplied through the sensor unit 40. The charge amplification circuit 31 includes
The capacitor C is connected via the analog switch 42, and the capacitance connected to the charge amplification circuit 31 is switched by turning on / off the analog switch 42. The waveform shaping circuit 32 has a high pass filter, a low pass filter, and a Schmitt trigger circuit.

The input ports I ₃ and I of the control unit 30 are also included.
_Although not shown in FIG. 2, the aperture setting switch 33a and the unit selection switch 33b, which are mounted on the printed circuit board 24, are connected to the switch 4, respectively. The switches 33a and 33b are similar to the analog switch 43. When the power source V _CC is supplied via the power source, a signal of H or L level is applied to the input ports I ₃ and I ₄ depending on the ON / OFF state. To the input port I ₅ of the control unit 30, the output of the conversion circuit 33c for converting the temperature detected by the temperature sensitive element 12 including a thermistor into a voltage is connected,
This temperature-voltage conversion circuit 33c is an analog switch 43.
When the power source V _CC is supplied via the voltage sensing element 12, a voltage signal having a magnitude corresponding to the temperature detected by the temperature sensing element 12 is applied to the input port I ₅ . The analog voltage applied to the input port I ₅ is A / D converted in the control unit 30. The reset switch 33d is operated to reset the control unit 30 is connected to an input port I _6.
The control inputs of the analog switches 41 to 43 are connected to the output ports O _{1 to} O ₃ of the control unit 30, and the control unit 30 controls ON / OFF thereof.

Further, the output port O ₄ of the control unit 30 is connected to a display device 26 arranged on the upper surface of the upper case 22. The control unit 30 also has an output port O ₅ for outputting the measured flow rate value data and a power supply input port V _CC for inputting the operating power supply of the control unit 30, and the output port O ₅ and the power supply input port V _CC are An external power supply input / external output unit 34 is connected to the power supply input port V _CC, and the battery 25 is connected thereto. The external power source input / external output section 34 is used for the D / A 24V conversion circuit 3
4a, a level shift circuit 34b, and a 4 to 20 mA output circuit 34c.

The charge amplifying circuit 31 is as shown in FIG.
Between the output terminal of the operational amplifier OP and the inverting input terminal.
Densa C₀Is connected, and its gain
(Sensitivity) is this capacitor C₀Determined by Operation
The piezoelectric element 13b connected to the input of the amplifier OP is generated.
Charge q is q∝F in proportion to the force, so q∝V²When
Then, a charge proportional to the square of the flow rate (flow velocity) is generated.
It will be. The piezoelectric element 13b is generated in the charge amplification circuit 31.
The electric charge q to be input is input, and this is converted into the voltage v. v =-
q / C₀Since there is a relationship of v ∝ −V²/ C₀Next to
Therefore v∝-f ²/ C₀And as shown in FIG. 8 (b)
Therefore, the output voltage v is proportional to the square of the frequency f.
It The relationship between the frequency f and the flow rate Q is shown in FIG.
There is a linear relationship.

In general, a small aperture has a small electric charge but a high frequency. Further, a large aperture has a characteristic that the generated electric charge is large but the frequency is low. It is conceivable to determine a unique value for this capacitor for each aperture and take measures by hardware, but this would increase the number of models.

Therefore, in this embodiment, as shown in FIG. 9, when the aperture is small, only the first capacitor C ₀ having a small capacitance is effective, and when the aperture is large, the first capacitor C ₀ and the first capacitor C ₀ are effective. So that the capacitor C of 2 becomes effective,
A second capacitor C is connected between the output terminal and the inverting input terminal of the operational amplifier OP via the analog switch 42. Further, in the ROM 30a, there is prepared a table defining what percentage of the rated flow rate at the diameter set by the diameter setting switch 33a the analog switch 42 is turned on / off. Therefore, when the aperture is set, the operational amplifier O is disabled by disabling or enabling the second capacitor C according to the value in this table.
The capacitance connected between the P output terminal and the inverting input terminal is switched. What percentage of the switching point K is set in a region where the output voltage v is not saturated, as shown in FIG.

Since the output voltage v includes the frequency component f (Hz) for pulse measurement as signal information, charge-voltage conversion is performed by the charge amplifier circuit so as not to be saturated, and the frequency (pulse ) Is input to measure and calculate, but when the analog switch is on, the first capacitor and the second capacitor act, and v∝-f ²
/ (C ₀ + C). When the output voltage v is largely saturated, the waveform of each part in FIG. 9 when it is not saturated shown in FIG. 11 is deformed as shown in FIG. 12, and the pulse after waveform shaping is on both sides of the original pulse. A pulse that causes a miscount will be generated, but by configuring the charge amplification circuit by switching the two capacitors as described above, correct measurement is realized and the number of models is reduced to reduce the cost. You will be able to plan.

When the mode changeover switch 27a is turned on, the control section 30 outputs a signal to the output port O ₃ to turn on the analog switch 43, and as shown in FIG. 13, the temperature sensitive element is provided between the analog switch 43 and the ground. A voltage is supplied to the resistor R ₁ in the temperature-voltage conversion circuit 33c connected via 12 and the reference voltage Vref is set to A / in the control unit 30.
Input for D converter (not shown). The voltage Vout at the connection point between the resistor R ₁ which is the output of the temperature-voltage conversion circuit 33c input to the input port I ₅ and the temperature sensitive element 12.
Vout = [Rth / (Rth + R ₁ )] · Vref, where Rth is the resistance value of the temperature sensitive element 12. The Vout input to the input port I ₅ of the control unit 30 is 00h by the 8-bit converter.
Converted to FFh.

When Vout = 0, the A / D value is 00.
When h and Vout = Vref, the A / D value is FFh. 8
Which temperature (° C) the A / D value of the bit corresponds to is determined by the characteristic value of the temperature sensitive element 12 and the value of the resistor R ₁ ,
R in the control unit 30 that has been tabulated in advance during programming
It is stored in the OM 30a. Therefore, 8-bit A / D
Depending on the value, the value referenced from the table in the ROM can be displayed on the display unit 26. Even when the temperature is being displayed, the measurement calculation is executed at the measurement timing.

The CPU 30 'performs input signal treatment, calculation, display and output signal processing according to a control program, and when the number of pulses input to the input port I ₂ per second is f (Hz), the instantaneous flow rate value is Calculate in (1). Q = ai * f + bi (1) where ai and bi are specific constants depending on the conditions such as the diameter and material of the flowmeter. Further, the above equation is not necessarily linear, and linearity tends to be poor especially on the low flow rate side of a flowmeter having an arbitrary diameter. Therefore, one aperture is divided into 5 sections, and for this reason,
The values and bi values are tabulated and stored in the ROM.

The diameter setting switch 33a is set on the measurement display unit 2 because ai and bi are different depending on the diameter and material of the measuring unit body 1 and the gain of the charge amplification circuit 31 is different. Further, the unit selection switch 33b is set to L / min when measuring the instantaneous flow rate.
And m ³ / h display are selected, 1L, 0.0 at the time of integrated flow rate measurement
It is for selecting 1 m ³ , 0.1 m ³ and 1 m ³ .

The reset switch 33d is provided separately from the power-on reset.
And 33b are provided to allow manual resetting when switching between 33 and 33b. When the reset switch 33d is turned on,
The control unit 30 outputs, for example, an H level signal to the output port O ₃ to turn on the analog switch 43 to supply power to the switches 33a and 33b, and to the input ports I ₃ and I ₄ according to the state of each switch. The applied H or L level signal is read and the setting state is stored in a predetermined area of the RAM 30b.

The mode changeover switch 27a selects one of the three modes by turning on the switch, and sequentially operates the instantaneous meter operation in mode 1, the integrated total flow rate operation in mode 2, and the integrated batch operation in mode 3. select. The outline of each operation mode will be sequentially described below.

In the instant meter operation, the number of pulses input to the input port I ₂ is counted in one second of a three-second cycle, and the remaining time is calculated by moving average of two pulses (previously counted value). And average count value this time), calculation of instantaneous flow rate value, correction calculation, addition of integrated value, from L / min to m ³ / h, L
Unit conversion from m to m ³ , display on the display 26, and output to the output port O ₂ . In order to perform the moving average, an area for storing the previous count value is set in the RAM 3
It is formed in 0b, and the present count value is stored in this area before the next counting. Further, other processing is performed even for 1 second during pulse counting. The displayed value is a three-digit display of the instantaneous value, and the output to the output port O ₄ is coded. For this reason, for example, an H-level signal is output to the output port O ₁ to turn on the analog switch 41 only immediately before the period when the pulse counting is performed and the measurement is started until the measurement is completed. Power supply to all the sensor units 40 is controlled.

The integrated total flow rate operation is the same as the instantaneous continuous operation except that the displayed value is an 8-digit display of the integrated value. The cumulative batch operation is the same as the cumulative total flow operation except that the cumulative value in the RAM 30b up to that point is cleared and a new cumulative operation is started.

When the CPU 30 'detects a voltage drop, it flashes the "BAT" segment display 26f to request battery replacement, but at this time, it continues to operate in the current operation mode and starts monitoring for power failure. When the recovery of the voltage drop is detected, the power failure monitoring is stopped. This blink is 0.
It will be on for 5 seconds and off for 0.5 seconds. When a power failure is detected, only the "BAT" segment display 26f and the unit segment display 26c or 26d are lit, the other displays are blank, and the latch output for the output port O _{3 is set} to 0.
And then wait. Depending on the operation mode, the "ECO" segment display 26e may also light up.

When the power failure is restored and the voltage drop is also restored due to battery replacement or the like, the CPU 30 'is controlled by the RAM 30b.
Depending on the contents saved in, the operation mode immediately before entering the waiting state is automatically restored and the operation is restarted.

In order to perform the above-described operation in the power saving mode, power supply to the analog circuit parts such as the amplifier circuit 31 and the waveform shaping circuit 32 is started by the control of the analog switch 41 for the above 1 second, that is, pulse measurement. 0 of the period.
I try to do it for 1.5 seconds from 5 seconds ago to the end of 1 second.

When the fluid is flowing during the integrated total flow rate operation, the four bar segment displays 26g are turned on for 0.5 seconds, turned off for 1.5 seconds, and rotated from left to right. When there is no flow, the bar segment display 26g is turned off. Even when the CPU 30 'is in the waiting state, the segment of the display 26 is made to blink when necessary except during a power failure operation.

Details of the operation outlined above are shown in FIG.
This will be described in detail below with reference to the processing flowchart of the CPU 30 'shown in FIG.

The CPU 30 'starts the reset operation shown in the flowchart of FIG. 14 by turning on the power source or by turning on the reset switch 33d. After performing initial processing in the first step S1, the CPU 30' proceeds to step S2 and displays here. All segments of the vessel 26 for 3 seconds
It blinks by turning on and off every 0.5 seconds. After that, the process proceeds to step S3 to output an H level signal to the output port O ₃ to turn on the analog switch 43. Next, in step S4, the setting data relating to the aperture set by the aperture setting switch 33a is read and stored in a predetermined area of the RAM 30b. Then, in step S5, the selection data relating to the unit selected by the unit selection switch 33b is read and is read in the RAM3.
It is stored in a predetermined area of 0b. After that, the process proceeds to step S6, the L level signal is output to the output port O ₃ , the analog switch 43 is turned off, and then the process proceeds to step S7 to perform the flow meter process described later.

In the flow meter process of step S7, as shown in the flowchart of FIG. 15, first, the instantaneous meter operation of mode 1 is performed in step S7a. After that, in step S7b, it is determined whether or not the operation of step S7a is continued depending on whether or not there is mode switching. If this determination is NO and the operation is not continued, the process proceeds to step S7c. In step S7c, the integrated total flow rate operation of mode 2 is performed, and then in step S7d, it is determined whether or not to continue the operation of step S7c based on whether or not there is mode switching. If this determination is NO and the operation is not continued, step S7e Proceed to. In step S7e, the integrated batch operation of mode 3 is performed, and then in step S7f, it is determined whether or not to continue the operation of step S7e based on whether or not there is a mode switching.
Then, the above process is repeated.

The CPU 30 'also performs the flow rate measuring process of the flow chart of the main routine shown in FIG. 16 which is started by turning on the power source, and determines in the first step S11 whether or not it is the cycle start point. The cycle of this determination is, for example, 3 seconds, and becomes the cycle start point, and step S
If the determination result in 11 is YES, the process proceeds to step S12, the number of pulses input to the input port I ₂ is counted, and then the process proceeds to step S13. In step S13, it is determined whether the determination in step S11 is YES, that is, whether or not one second has elapsed from the start of the cycle, and when the determination is ΝO, the process returns to step S12. Therefore, the pulses input to the input port I ₂ are counted for 1 second until 1 second has elapsed and the determination in step S13 becomes YES. After 1 second has passed, the determination in step S13 is YE.
When it becomes S, the process proceeds to step S14, where the output port O
_The level of ₁ is changed from H to L to turn off the analog switch 41 to stop the power supply to the sensor unit 40.

After that, the process proceeds to step S15, where the flow rate is calculated based on the counted value of the pulse. This calculation is performed according to the above equation (1). Then, the process proceeds to step S16, where it is determined whether or not there is a flow in this measurement.
By executing this step S16, the CPU 30 'functions as the current flow detection means 30-2 for detecting the presence or absence of the fluid flow by the current measurement by the instantaneous flow rate measurement unit.
This determination is made depending on whether or not there is a pulse count in step S12. The determination in step S16 is YE.
If S, the process proceeds to step S17 to add the integrated total flow rate value, and then proceeds to step S18 to add the integrated batch flow rate value. The addition in steps S17 and S18 is performed by adding the flow rate measured in step S15 to a predetermined integrated total flow rate value area and integrated batch flow rate value area in the RAM 30a. Then step S
Proceeding to 19, the bar segment display 26g of the display 26 is rotated while blinking, and the display indicates that there is a flow.

After that, the process proceeds to step S20, where it is determined whether or not the flow is equal to or more than a set value (110% of the rated flow rate). If this determination is ΝO, the analog switch 42 is turned off in step S21 and the sensor unit is detected. The gain of 40 is increased, and when the determination is YES, the analog switch 42 is turned on in step S22 to reduce the gain of the sensor unit 40, and then the process proceeds to step S23. Step S2
In 3, it is determined whether there is a flow in the previous measurement. By executing this step S23, the CPU 30 'functions as the previous flow detecting means 30-3 for detecting the presence or absence of the flow of the fluid by the previous measurement by the instantaneous flow rate measuring unit. This determination is made based on whether or not there was a previous pulse count in step S12. When the determination in step S23 is YES, the process proceeds to step S24, the moving averages of the count values of the previous time and the present time are taken as an instantaneous display value, and then the process proceeds to step S28. When the determination in step S23 is NO, the process proceeds to step S25, where the current instantaneous value is set as the instantaneous display value, and then the process proceeds to step S28. Further, when the determination in step S16 is NO, the process proceeds to step S26, the bar segment display 26g of the display unit 26 is turned off, and the process proceeds to the next step S27 to set the instantaneous display value of this time to 0.
After that, the process proceeds to step S28. Step S2 above
By executing S4, S25, S27 and step S28 described later, the CPU 30 'functions as the display control means 30-4.

In step S28, the instantaneous flow rate value or the integrated flow rate value is output to the display 26, and in the next step S29, the instantaneous flow rate value or the integrated flow rate value is output to the output port O ₅ . It proceeds to step S30. In step S30, whether or not 0.5 seconds before the pulse measurement is judged by the time measured by the cycle timer,
After waiting for this determination to be YES, the process proceeds to step S31, where the output port O ₃ is changed from L to H level to turn on the analog switch 41 to supply power to the sensor unit 40, and then the process returns to step S11. .

When the mode changeover switch 27a is operated during execution of the main routine of FIG. 16 and the input port I ₁ falls from the H level to the L level, the execution of the mode change interruption routine of FIG. 17 starts accordingly. Then, in the first step S41, the current mode is displayed blinking on the most significant digit of the small number display portion 26a of the display unit 26, and then the process proceeds to step S42 to turn on the analog switch 43. Next, in step S43, the temperature signal input to the input port I ₅ is A / D converted, and then in step S4.
4, the temperature display data is obtained by referring to the temperature table in the ROM 30a by the A / D conversion value. The temperature display data obtained in step S44 is used in the next step S44.
At 45, the current fluid temperature is displayed by outputting it to the display 26, and then the process proceeds to step S46.

In step S46, it is determined whether or not the operation of the mode changeover switch 27a has disappeared and the input port I ₁ has become H level. When the determination in step S46 is YES, the process proceeds to step S47, and it is determined whether or not 3 seconds have elapsed from the first input.
When it is O, the process proceeds to step S48. In step S48, it is determined whether or not there is a second input. If this determination is NO, the process returns to step S43, and the determination is Y.
If ES, go to step S49. Step S49
In, the analog switch 43 is turned off, and the current mode is advanced by one in the next step S50. Then, the process proceeds to step S51, the data of the new mode advanced by one is output to the display device 26 and displayed, and then the process returns to step S47 to restart the process from the first input to 3
Determines whether seconds have elapsed.

When the determination in step S46 is NO,
That is, when the mode changeover switch 27a is operated and the input port I ₁ is at the L level, step S5 is performed.
Then, it is determined whether or not the L level continues for 5 seconds or more. If this determination is NO, step S47.
If the determination is YES, that is, if the mode changeover switch 27a has been operated for 5 seconds continuously, the process proceeds to step S54 to determine whether or not the current mode is 1, and if the determination is YES. Return to the main routine.

When the judgment in step S54 is NO, the routine proceeds to step S55, in which it is judged whether or not the current mode is 2, and when the judgment is YES, the reset start routine of FIG. 14 is executed. By executing this reset start routine, the integrated total flow rate value in the RAM 30b is cleared in the initial processing of step S1. When the determination in step S55 is NO, the process proceeds to step S56, where the integrated batch flow rate value data in the RAM 30b is cleared, and then the process proceeds to step S57 to turn off the analog switch 43 and return to the main routine with the mode set to 3. .

As is clear from the above description, the CPU 3
Reference numeral 0 ′ serves as an instantaneous flow rate measuring unit 30-1 that measures the instantaneous flow rate by a signal corresponding to the flow rate of the fluid generated by the sensor unit 40.

In the above embodiment, the detecting means 30-
2 detects the presence or absence of the flow of the fluid by the current measurement by the instantaneous flow rate measurement unit, but determines whether or not there is a pulse count value. Good. In this case, the moving average is performed for the instantaneous flow rate obtained by the count value of each time. The same thing can be said in the case of detecting the presence or absence of the fluid flow by the previous measurement by the previous flow detection means 30-3.

[0057]

As described above, according to the present invention, the moving average value of the instantaneous flow rate measured when the presence of fluid flow is detected by this measurement and the presence of fluid flow is detected by the previous measurement. Since it is displayed, it is possible to prevent the displayed value from flickering due to pulsation of the flow, and when 0 is displayed, it is displayed regardless of what kind of flow there was before this time. has become the flickering is prevented, yet in so that it is possible to the flow rate value 0 of reality without the display value at the time of the fall time
It Therefore, the measurement result of this time by the instantaneous flow rate measurement unit
The flow indicator means that the flow indicator indicates no fluid flow.
And the timing at which the displayed value of the instantaneous flow rate becomes 0
You can also let it .

[0058] In addition, flow display means, the mode switching
The display means displays either the integrated flow rate value or the instantaneous flow rate.
Even if it is, it is effective to directly notify the presence or absence of fluid flow
However, whether the flow of fluid is displayed on the display means
It is especially effective when displaying the integrated flow rate value.
is there. Moreover, the instantaneous flow rate is displayed on the display by switching the mode.
Is displayed, the current flow detection means is
What kind of flow was there before it was detected
0 is displayed on the display regardless of whether or not
Then, the flicker on the display was prevented and the flow rate became 0.
The actual display value can be set to 0 without taking time.
It is like this. Therefore, the flow display means
The timing to display no flow and the display value of the instantaneous flow rate are 0
The timing can be matched .

[0059]

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a flow meter according to the present invention.

2A and 2B are structural views showing an embodiment of a flowmeter according to the present invention, FIG. 2A is a top view, FIG. 2B is a sectional view, and FIG.

3 is an enlarged cross-sectional view of a part of the flow meter in FIG.

FIG. 4 is a diagram for explaining the operation principle of the flow meter in FIG.

5 is a characteristic graph used for explaining the operation principle of FIG. 4. FIG.

FIG. 6 is a block diagram showing a circuit configuration of the flow meter of FIG.

FIG. 7 is a circuit diagram showing a specific example of the charge amplification circuit in FIG.

8 is a graph used to explain the operation of the charge amplification circuit of FIG. 7. FIG.

9 is a circuit diagram showing a specific example of a part of FIG.

FIG. 10 is a graph used to describe the operation of FIG.

FIG. 11 is a waveform diagram showing waveforms of respective parts in one operating state of the circuit in FIG.

FIG. 12 is a waveform diagram showing waveforms of respective parts in another operating state of the circuit in FIG. 9.

FIG. 13 is a circuit diagram showing a specific example of another part of FIG.

14 is a flowchart showing a processing operation of the CPU of FIG.

15 is a flowchart showing details of one step in FIG.

16 is a flowchart showing a main routine of a processing operation of the CPU of FIG.

FIG. 17 is a flowchart showing an interrupt routine of a processing operation of the CPU of FIG.

[Explanation of symbols]

26 indicator (display means) 26g flow display section (flow display means) 30-1 CPU (instantaneous flow rate measurement section) 30-2 CPU (current flow detection section) 30-3 CPU (previous flow detection section) 30-4 CPU (Display control means) 40 Sensor unit

Front Page Continuation (56) References JP 63-187120 (JP, A) JP 57-189071 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01F 1 / 00 G01F 15/06 G01P 3/00

Claims (2)

(57) [Claims] 1. A sensor section for generating a signal pulse having a cycle corresponding to the flow rate of a fluid flowing in a flow path, and an instantaneous flow rate for measuring the instantaneous flow rate by counting the pulses generated by the sensor section for a fixed period of time. A measuring unit, a display unit for displaying the instantaneous flow rate measured by the instantaneous flow rate measuring unit, and the instantaneous flow rate measurement
The presence or absence of fluid flow is detected by the measurement result of this time by the department
The current flow detection means and the current flow detection means
If there is a flow, it means that there is a flow.
No flow when the detection means detects no fluid flow
In flow meter and a flow display means for displaying each of the previous flow detecting means for detecting the presence of fluid flow through previous measurement results by pre Symbol instantaneous flow rate measurement unit, the is now flowing detecting means there fluid flow The moving average value of the instantaneous flow rate measured by the instantaneous flow rate measuring unit when the previous flow detecting means detects the presence of the fluid flow, and the current flow detecting means does not flow the fluid. And a display control means for displaying 0 on the display means when the flowmeter is detected. 2. A sensor section that generates a signal pulse having a cycle corresponding to the flow rate of a fluid flowing in a flow path, and an instantaneous flow rate that measures the instantaneous flow rate by counting the pulses generated by the sensor section for a fixed period of time. a measuring unit, display means for displaying the instantaneous flow rate measured by the instantaneous flow rate measurement unit, the instantaneous flow rate measurement
The presence or absence of fluid flow is detected by the measurement result of this time by the department
The current flow detection means and the current flow detection means
If there is a flow, it means that there is a flow.
No flow when the detection means detects no fluid flow
And a flow display means for displaying
In the stage, by switching the mode, instead of the instantaneous flow rate,
Sequentially adding the instantaneous flow rate measured by the instantaneous flow rate measurement unit
In to flowmeter integrated flow value that designed to render obtained, and the previous flow detecting means for detecting the presence of fluid flow through previous measurement results by pre Symbol instantaneous flow rate measurement unit, the current flow detection When the means detects the presence of a fluid flow and the previous flow detection means detects the presence of the fluid flow, the moving average value of the instantaneous flow rate measured by the instantaneous flow rate measuring unit is displayed on the display means, and the current flow is displayed. The detection means
A flow controller, comprising: display control means for displaying 0 on the display means when no fluid flow is detected .