JPH0783725A - Flowmeter - Google Patents

Abstract

PURPOSE:To obtain a flowmeter which can accurately output pulses at every unit flow rate without sacrificing the detecting accuracy and measuring range by providing a sensor which converts the flow rate of a fluid into pulse signals, control means, and pulse width generating means. CONSTITUTION:A sensor means 3 converts the flow rate of a fluid into pulse signals at a prefixed rate (pulse rate). When the pulse signals are inputted, a control means 4 detects and counts the pulse signals, converts the pulse signals into the flow rate by multiplying the pulse signals by the pulse rate, and finds the cumulative flow rate of the fluid by adding the converted flow rate from time to time. The variation of the cumulative flow rate is monitored and whether or not the variation exceeds a fixed amount is detected B. When the variation exceeds the fixed amount, a pulse outputting means C outputs a pulse TR for driving a pulse width generating means 5. The means 5 outputs a pulse PLS having a pulse width broader than a pulse width decided by the count value of a counter 6. Since the pulse width generating means 5 generates a pulse width in accordance with the driving pulse outputted from the control means 4, the processing work of the control means 4 is reduced and the flow rate of the fluid can be accurately measured even when the flow rate is large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic flow meter which outputs a pulse at a constant flow rate.

[0002]

2. Description of the Related Art A conventional flow meter will be described using a water meter. A water meter is used to measure an integrated flow rate for each customer, read a meter, and collect a charge.Generally, a sensor unit for detecting the flow rate and an integrated flow rate from the flow rate detected by the sensor unit are used. It is composed of a calculating means for obtaining and a display means for displaying the integrated flow rate. By the way, most of these meters are installed independently, and meter readers operate by a method of visiting a customer to read the meter and collecting the fee at a later date. However, when the meter is read by a meter reader, it may be difficult to read the meter when it is installed in a narrow place, a low place, or a closed place. For this reason, in order to display the integrated flow rate in a place where it is easy to read the meter, a device called a remote measurement indicator is connected, and a pulse signal is sent from the water meter for each unit flow rate, and the remote measurement indicator counts the pulses for each unit flow rate. To display the integrated flow rate.

FIG. 10 shows a block diagram of an electronic water meter having such a pulse sending function. 1 is a flow meter which the water meter is composed of, 2 is a remote display, 3 is a sensor means,
Reference numeral 4 is a control means. The control means 4 is usually composed of a microcomputer and comprises an integrated flow rate calculation means A, a unit flow rate calculation means B, a pulse output means C, and a pulse width generation means D.

The sensor means 3 converts the flow rate into a pulse signal having a frequency corresponding to the flow rate, and the integrated flow rate calculating means A of the control means 4 adds the flow rates according to the pulses to obtain the integrated flow rate. The unit flow rate calculation means B monitors the amount of change in this integrated flow rate and detects whether or not there is a change in a predetermined fixed amount. When there is a change of a certain amount, the pulse output means C outputs the pulse width determined by the pulse width generation means D. The pulse width has a lower limit that is longer than or equal to the detectable length of the remote display 2, and the pulse width generation means D manages the time equal to or longer than the lower limit.

[0005]

The water meter is required to have a fine detection accuracy and a wide measurement range. However, in the above conventional configuration, the processing capacity is limited because the processing is performed by software, and the integration If the calculation of the flow rate is prioritized, the output of the pulse for each unit flow rate will be delayed or forced to be prohibited, and there is a risk that the correct display cannot be performed with the remote sensing needle detector. On the contrary, when the pulse output for each unit flow rate is prioritized, the detection of the flow rate and the calculation of the integrated flow rate must be sacrificed, and the accuracy and measurement range cannot be guaranteed. To solve these problems, it is necessary to improve the processing capability of the microcomputer, but since most of these meters are battery-operated, it is desirable to use a microcomputer that operates at low speed with low current consumption. In addition, it was not possible to easily use expensive high-performance products in terms of cost.

The output pulse differs depending on the connected equipment. In addition to pulse output for each unit flow rate, there are devices that require the output signal of the sensor means, and to switch between these, a method of switching using a switch in circuit was used, but this method is easy after manufacturing. It is not possible to change the setting to a different value, and it is necessary to create different types, which leads to a decrease in manufacturing efficiency.Because the pulse width cannot be adjusted, the reception may not be received if the flow rate increases depending on the connected equipment. There were challenges that would be possible.

The present invention is intended to solve the above problems, and an object thereof is to provide a flow meter capable of correctly outputting a pulse for each unit flow rate without sacrificing detection accuracy and measurement range. is there.

A second object of the present invention is to make it possible to easily switch between two types of pulses and to output a pulse width according to the connected equipment.

[0009]

In order to achieve the above object, the present invention comprises a sensor means for converting a flow rate into a pulse signal, a control means for receiving a signal from the sensor means for processing, and a pulse width generating means. The control means is configured to include a unit flow rate detection means for detecting an increase / decrease in a predetermined amount of flow rate, and a pulse output means for outputting a pulse.

The control means further comprises an output selection signal output means for outputting an output selection signal, and the pulse width generation means outputs the output selection signal output from the output selection signal output means and the signal output from the sensor means. A signal having a predetermined pulse width is output according to the logical sum of the logical product of the above and the pulse signal output by the pulse output means.

[0011]

According to the present invention, the control means counts the pulse having the frequency corresponding to the flow rate by the sensor means, and the unit flow rate detecting means detects the increase or decrease of the predetermined amount with respect to the integrated flow rate. The output means outputs a pulse. The pulse width generation means connected to the control means upon detecting this pulse works so as to output a signal having a predetermined pulse width. Therefore, the control means does not need to manage the pulse width of the output signal of the flow meter, the work of the control means can be reduced, and the integrated flow rate can be detected correctly.

Further, the switching means in the control means outputs an output selection signal of a level required, and the pulse width generation means outputs the output selection signal output by the output selection signal output means and the sensor means. AND of signals and
It functions to output a signal having a predetermined pulse width in accordance with the logical sum of the pulse signal output by the pulse output means. For this reason, the output timing of the output signal of the pulse width generation means is determined by the output signal of the sensor means or the unit flow rate output by the pulse output means according to the level of the signal output by the output selection signal output means of the control means. Can be switched to pulse.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a flowmeter according to an embodiment of the present invention, and FIG. 2 is a simple flow chart for explaining the operation thereof. FIG. 3 is a configuration example of the pulse width generating means of the present invention, and FIG. 4 is a diagram for explaining the specific operation thereof.

In the figure, 1 is a flow meter which constitutes a water meter, 2 is a distance display, 3 is sensor means, 4 is control means, 5 is pulse width generation means, and as shown in FIG. It is composed of 7. The control means 4 is composed of a microcomputer and comprises an integrated flow rate calculation means A, a unit flow rate calculation means B, and a pulse output means C.

The counter 6 has a count enable signal (EN).
Is activated when H becomes high, and when the rising edge of the clock signal (CLK) is counted four times, the count end signal (RCO)
To H.

The flow rate is converted into a pulse signal by the sensor means 3 at a predetermined ratio (pulse rate). The control process of the control means 4 is divided into a normal processing process and an interrupt processing process, and when the pulse signal is input, pulses are detected (A1) and counted (A2) in the interrupt processing process. This counted pulse is multiplied by the above-mentioned pulse rate in a normal processing step and converted into a flow rate (A
3), which is added at any time to obtain the integrated flow rate (A4). The unit flow rate calculation means B monitors the amount of change in this integrated flow rate and detects the presence or absence of a predetermined fixed amount of change (B1). When there is a change of a certain amount (B2), the pulse output means C drives the pulse (T
R) is output. This pulse signal TR is input as the reset signal (RST) of the counter 6, and the signal RS
When T becomes H, the count end signal RCO is reset and becomes L. Therefore, an inverted signal (PL) of the count end signal RCO inputted as the count enable signal (EN) (PL
Since S) becomes H, the counter 6 counts the clock signal (CLK) four times from the falling of the reset signal (RST), and when the count end signal RCO becomes H, the inversion signal PLS becomes L, so that a pulse is generated thereafter. The operation is stopped until the pulse signal TR output from the output means C is input,
As a result, the pulse width generation means 5 outputs a pulse (PLS) having a pulse width equal to or larger than the pulse width determined by the count number of the counter 6. Since the pulse width generation means 5 creates the output pulse width in accordance with the drive pulse output by the control means 4 in this way, the processing content in the control means 4 is reduced, and there is a pulse width generation step in which interrupt processing must be prohibited. Since it does not exist, accurate flow rate measurement is possible even at high flow rates. Further, when the counter is used, the control means operates using the normal clock, so that signals can be shared and the configuration becomes simple.

Another embodiment of the present invention will be described with reference to FIGS. In the figure, 1 is a flow meter which constitutes a water meter, 2 is a distance display, 3 is sensor means, 4 is control means, and 5 is pulse width generation means, and as shown in FIG. It is composed of a circuit 9. The control means 4 is composed of a microcomputer and comprises an integrated flow rate calculation means A, a unit flow rate calculation means B, a pulse output means C, and an output selection signal output means E.

The output selection signal output means E of the control means 4 is
L is output when a pulse for each unit flow rate is required due to settings made in advance by communication or switch operation, and H is output when an output signal of the sensor means is required.

The logic circuit 9 outputs the output selection signal (SC) output by the output selection signal output means E in the control means 4.
T), the pulse signal (TR) output by the pulse output means C, and the output signal (MR) of the sensor means 3,
As a trigger signal (TR ') of the monostable multivibrator 8, a signal represented by a logical expression (MR * SCT) + TR is output. The monostable multivibrator 8 operates at the rising edge of the trigger signal (TR '), and has a pulse length (t) determined by the constant of the built-in circuit.
Pulse (PLS) is output.

When the output is set to the pulse for each unit flow rate, the control means 4 outputs L as the output selection signal SCT by the output selection signal output means E. When a signal is input from the sensor means 3, the control means 4 outputs a pulse TR for each unit flow rate, as in the previous embodiment.
Here, since the output selection signal SCT is L, the output TR ′ of the logic circuit 9 of the pulse width generation means 5 is MR * SCT = L.
And TR '= TR. By inputting this TR ', the monostable multivibrator 8 outputs a pulse having a pulse width (t) predetermined for each unit flow rate.

On the other hand, when the output is set to the output signal of the sensor means 3, the control means 4 causes the output selection signal output means E to output H as the output selection signal SCT.
Further, when a signal is input from the sensor means 3, the control means 4 calculates the integrated flow rate in the same manner as in the previous embodiment, but since it is set to the output signal of the sensor means 3, the pulse TR for each unit flow rate is set. Is not output and is always L. Here, since the output selection signal SCT is H, the output TR ′ of the logic circuit 9 of the pulse width generating means 5 becomes MR * SCT = MR, and T
R '= MR. By the input of TR ′, the monostable multivibrator 8 outputs a pulse having a predetermined pulse width (t) in synchronization with the output signal of the sensor means 3.

Since the pulse width generation means 5 switches the output timing of the output pulse according to the signal SCT output from the output selection signal output means E in this manner, the pulse output for each unit flow rate or the output of the sensor means 3 is simple. Can be obtained. Further, in particular, when the output of the sensor means 3 is output, compared with the case of using software,
Since the processing content of the control means 4 is remarkably reduced and there is no pulse width generation step, correct flow rate measurement is possible even at a high flow rate. Further, as compared with the case where the counter is used, the pulse width can be managed correctly and the clock signal need not be supplied, so that the stop mode operation of the microcomputer can be selected and power saving can be realized.

[0024]

As described above, the flowmeter of the present invention is
The load on the software is reduced because the pulse width generation means makes the pulse longer than the specified length according to the trigger signal that outputs the pulse for each unit flow rate that causes the extension of the processing time when processing by software according to the software. Therefore, the accuracy and the measurement range can be guaranteed without sacrificing the detection of the flow rate and the calculation of the integrated flow rate. Therefore, the processing can be performed without improving the processing capability of the microcomputer, and the cost and current consumption of the microcomputer can be reduced.

Further, by switching the output pulse by the signal output by the output selection signal output means,
It is possible to easily make changes after manufacturing, and it is not necessary to make different output signals for each type of output signal, which has the effect of improving manufacturing efficiency.

Further, when the counter is used as the pulse width generating means, there is an effect that the above can be realized with a simple structure by using the clock of the microcomputer, and the pulse length is equal to the clock cycle. Since it depends on the frequency division ratio, a stable output can be obtained with respect to fluctuation factors such as temperature, and an effect can be obtained especially for a flow meter which is attached outdoors in which temperature is unstable.

On the other hand, when the monostable multivibrator is used as the pulse width generation means, the clock of the microcomputer is not used, so that the power saving operation state in which the clock of the microcomputer is stopped can be set. The battery life can be extended. Further, since the pulse length of the output pulse depends on the internal circuit constant and does not depend on the pulse width of the trigger signal, there is an advantage that pulse outputs of the same length can always be obtained in the same environment.

[Brief description of drawings]

FIG. 1 is a block diagram of a flow meter according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of FIG. 1 above.

FIG. 3 is a block diagram showing an example of the configuration of the pulse width generation means shown in FIG.

FIG. 4 is a time chart for explaining the operation of the first embodiment of the present invention.

FIG. 5 is a block diagram of a flow meter according to another embodiment of the present invention.

FIG. 6 is a flowchart illustrating the operation of FIG. 5 described above.

FIG. 7 is a block diagram showing an example of the configuration of the pulse width generation means shown in FIG.

FIG. 8 is a time chart for explaining the operation of the second embodiment of the present invention.

FIG. 9 is a time chart for explaining the operation of the second embodiment of the present invention.

FIG. 10 is a block diagram of a conventional flowmeter.

[Explanation of symbols]

 1 Flowmeter 3 Sensor Means 4 Control Means 5 Pulse Width Generating Means A Cumulative Flowrate Calculating Means B Unit Flowrate Means Means C Pulse Output Means

Claims (4)

[Claims] 1. A sensor means for converting a flow rate into a pulse signal, a unit flow rate detecting means for counting the pulses output from the sensor means to detect an increase / decrease in a predetermined amount, and the unit flow rate detecting means. The control unit includes a pulse output unit that outputs a pulse when a predetermined amount of increase or decrease is detected, and a pulse width generation unit that outputs a signal having a predetermined pulse width when the pulse is input. Flowmeter. 2. The control means comprises an output selection signal output means for outputting an output selection signal, and the pulse width generation means comprises an output selection signal output from the output selection signal output means and a signal output from the sensor means. The flowmeter according to claim 1, wherein the flowmeter outputs a signal having a predetermined pulse width according to the logical sum of the logical product and the pulse signal output by the pulse output means. 3. The flowmeter according to claim 1, wherein the pulse width generating means is constituted by using a counter, and the clock signal of the counter constitutes an operation clock of the control means. 4. The flowmeter according to claim 1, wherein the pulse width generating means is composed of a monostable multivibrator.