JPH0461285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for measuring gas flow rate, and more particularly to a device for measuring gas flow rate per unit time.

Configuration of Conventional Example and its Problems Conventionally, for example, a membrane meter has been well known as a device for measuring the integrated flow rate of gas. There is also a membrane meter that has been modified for remote meter reading. In this meter for remote meter reading, a magnet is installed in the link mechanism provided to use the diaphragm used in the meter or the reciprocating motion of the diaphragm as the opening/closing force of the on-off valve in the meter body. It is configured to convert into electrical pulses using a magnetic sensor such as an IC, count these electrical pulses using a counter, and display the output. In this type of application, it is not necessary to know the instantaneous value, but only to know how much volume of gas the user has consumed, so such a so-called integrated type gas flow rate measuring device is desired. Naturally, with this type of device, it is not possible to know the flow rate per unit time which is relatively short.

OBJECT OF THE INVENTION The purpose of this invention is to measure gas flow rate with great accuracy.

Structure of the Invention The present invention includes: a flow rate pulse generator provided in a gas supply line and outputting a flow rate pulse according to a gas flow rate; a counter that counts the flow rate pulse;
A timer that starts measurement when the counter counts the first flow pulse and measures the time until a new flow pulse is input to the counter after a predetermined time has elapsed; This gas flow rate measuring device is constructed of a divider that performs division by taking the measurement time as a divisor input, and uses the calculation result of the divider as a flow rate signal per unit time.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The flow rate pulse generator 1 has a configuration similar to that used in the conventional device described above. For example, when a membrane type meter is used as a flow rate detector, a magnet provided on a diaphragm or its link mechanism is combined with a magnetic field sensor. The configuration is as follows. In this case, one pulse f _P is generated each time the diaphragm moves back and forth. When the diaphragm makes one reciprocation, a unit flow rate Qu flows, so the flow rate is calculated at each pulse interval of the flow pulse generator.
This means that Qu is flowing. The output pulse f _P of this flow rate pulse generator 1 is counted by a counter 2 . On the other hand, since counter 2 starts counting, timer 3
works. The timer 3 is configured to count the output pulses of the oscillator 31 with a counter 32. When the counter 32 counts a predetermined number of pulses from the oscillator 31, that is, when a predetermined time Tφ, for example, one minute has elapsed, it outputs a signal TB1 from the output 01 (FIG. 2B). After this, a new flow pulse f _P , that is, N in Fig. 2 A
When the th pulse is input to the counter 2, the logical product of this signal and the above-mentioned signal TB1, that is,
An output signal is generated at the AND gate 4 (FIG. 2C). Based on the output of the AND gate 4, the divider 5 is
The content of the counter 2, ie, the flow rate pulse count value N, is used as the dividend, and the content of the counter 32, ie, the measurement time T, is used as the divisor, and execution of division is started. The division result, ie, N/T, is output from the divider 5 and input to the latch 6. The division result N/T has the following physical meaning. The output period of the oscillator 31 is taken as a unit measurement time, and the flow rate per measurement time is expressed. Since the flow rate Qu flows at every pulse interval, in reality, during the measurement time T, (N
×Qu) flow rate has flowed. Therefore,
If Qu=1 and the output period of the oscillator 31 is, for example, 1 second, the output of the divider 5 is N/T(/
sec), which indicates the flow rate per unit time. The latch 6 is a pulse obtained by delaying the output of the AND gate 4 with the delay circuit 7 (Fig. 2 D).
Then, the input data, ie, the output of the divider 5, is latched. On the other hand, the output of the delay circuit 7 resets the counters 2 and 32, initializes both counters,
Start the next measurement. Therefore, at the Nth flow rate pulse f _P , one measurement ends and the next measurement starts. During the next measurement, the previous flow rate is stored in the latch 6.

According to the embodiment described above, the flow rate per unit time (for example, 1 second) can be accurately determined in a relatively short measurement time (for example, about 1 minute). The measurement time is the time until a new flow pulse is generated after a predetermined time Tφ (for example, 1 minute) has elapsed, and since the time of N flow pulses can be measured with the resolution of the output frequency of the oscillator 31, the desired time can be measured. In order to obtain measurement accuracy, high accuracy can be easily achieved by simply manipulating the output frequency of the oscillator 31.

FIG. 3 shows another embodiment of the present invention to accommodate many types of gas meters. For membrane gas meters, for example, the unit flow rate for one round trip of the diaphragm
As Qu, there are meters with flow rate types such as 0.6, 0.9, and 1.7, and these quantities are set with unit flow rate setting devices 8a, 8b, and 8c. On switch 9,
Select the type of meter to which the flow pulse generator is installed. In the figure, the flow rate setting device 8b is selected, and its unit flow rate is 0.9. The product of this value and the output of latch 6 is determined by multiplier 10. The output is (N×0.9)/sec. Multiplier 10
The multiplication start signal is a signal obtained by further delaying the output of the delay circuit 7 by the delay circuit 11. That is, after the data in latch 6 is latched, multiplication is started. The circuit of FIG. 1 is further provided with unit flow rate setters 8a to 8c for each meter, which are appropriately selected by a switch 9, and the product of the selected value and the output of the latch 6 is multiplied by a multiplier 10. By determining this, it is possible to accommodate a large number of meters.

Effects of the Invention A flow rate pulse generator provided in a gas supply line and outputting flow rate pulses in accordance with the gas flow rate, a counter that counts the flow rate pulses, and the counter starts measurement when counting the first flow rate pulse, A timer that measures the time until a new flow rate pulse is input to the counter after a predetermined time has elapsed, and a divider that executes division by inputting the counted value of the counter as a dividend and inputting the time measured by the timer as a divisor. Since the calculation result of the divider is used as a flow rate signal per unit time, the following effects can be obtained.

(1) A single timer measures the time from when the first flow pulse is input to when a new flow pulse is input to the counter after a predetermined time has elapsed, so accurate flow rate can be achieved with a simple configuration. can be calculated.

(2) It is not necessary to measure the period of the flow rate pulse, and the configuration is simple because there is no need for any means necessary for this purpose.

(3) Even if a constant flow rate is flowing, even if the flow rate pulse interval varies, it is averaged, so the flow rate per unit time can be measured accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electric circuit of a gas flow rate measuring device according to an embodiment of the present invention, FIG. 2 is a timing diagram for explaining the operation of FIG. 1, and FIG. 3 is a diagram of an apparatus according to another embodiment of the present invention. FIG. 2 is a block diagram of an electric circuit. 1...Flow rate pulse generator, 2...Counter, 3
...Timer, 5...Divider.

Claims (1)

[Claims] 1. A flow rate pulse generator installed in a gas supply line and outputting flow rate pulses in accordance with the gas flow rate, a counter that counts the flow rate pulses, and the counter starts measurement when counting the first flow rate pulse,
A timer that measures the time until a new flow rate pulse is input to the counter after a predetermined time has elapsed, and a divider that executes division by inputting the counted value of the counter as a dividend and inputting the time measured by the timer as a divisor. A gas flow rate measuring device comprising: a gas flow rate measuring device that uses the calculation result of the divider as a flow rate signal per unit time.