JPH06258104A - Flowrate meter - Google Patents

Abstract

PURPOSE:To accurately measure flowrate of gas and liquid. CONSTITUTION:A coefficient data group obtained from data sampled in advance out of fluid flowrate and the output signal of a flowrate detection means 8 are stored in a data memory means 10 and a correction factor for the scattering of flowrate detection means 8 is input to a correction data input means 11. Then the coefficient data group is corrected with a correction means 12 and a gradient is operated with the corrected coefficient group. And with using the output signal detected with the flowrate detection means 8, the corrected coefficient data of the data memory means 10, the operated gradient value and Lagrange function, the non-linear characteristic of the coefficient showing the relation between the flowrate and the flowrate detection means 8 is approximated by interpolation to obtain flowrate.

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 the flow rate of gas such as city gas, LPG gas or liquid such as tap water, and particularly to a flow meter using a fluidic element as a flow rate detecting sensor. Thus, the present invention relates to a flow meter which can easily and quickly correct the instrumental difference between the flow meters and has a highly accurate calculation function than the output signal of the flow sensor.

[0002]

2. Description of the Related Art Conventionally, a flow meter of this type has a structure as shown in FIGS. 4 and 5, as disclosed in Japanese Patent Laid-Open No. 3-44512.

That is, in the conventional flowmeter of FIG. 4, 1 is a flowmeter, 2 is a gas pipe, and 3 is a fluidic oscillation element, which causes fluid oscillation by utilizing the kinetic energy of the fluid. A piezoelectric film sensor 4 detects the frequency of fluid oscillation. A flow sensor 5 detects a flow rate in a small flow rate range. A shutoff valve 6 shuts off the gas supply when an abnormal use state is detected. Reference numeral 7 is a control device.

FIG. 5 shows the characteristics of the control device 7. The fluid flowing through the gas pipe 2 causes fluid oscillation when passing through the fluidic transmission element 3. The relationship between the oscillation frequency F and the fluid flow rate at that time is generally Q =
The flow rate is obtained by utilizing the fact that the linear approximation formula A · F + B holds. However, the fluidic oscillating element 3 does not hold the above-described linear equation in the entire flow rate range to be measured. Therefore, the constants A and B of the linear approximation equation are set for each oscillation frequency range where linear approximation is possible.
To obtain the flow rate. FIG. 5 shows a case where the linear approximation formula is switched at the frequency F0.

Next, since the constants A and B have variations, they are divided into 16 steps and set in advance. Then, the optimum combination of A0 and B0 is 16 in the frequency range up to F0.
Choose from among the stages. Similarly, if the frequency is F0 or higher, A
The optimum combination of 1 and B1 is selected from 16 steps and set. After performing the above processing, the flow rate is measured and the piezoelectric film sensor 4
Calculate the flow rate from the frequency detected from.

[0006]

However, in the above-mentioned conventional configuration, since the constant indicating the relationship between the flow rate and the vibration frequency (or cycle) is set only in 16 steps, there is an optimum value especially between the set steps. In this case, there is a problem that the instrumental difference becomes large and, as a result, the flow rate cannot be accurately measured and the integrated flow rate value is also affected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a flow meter capable of performing a more accurate flow rate calculation from the signal of the flow rate detecting means.

[0008]

In order to achieve the above object, the present invention provides a flow rate detecting means for detecting a fluid flow rate, an output signal of the flow rate detecting means and an output signal of the flow rate detecting means corresponding to the fluid flow rate in advance. Data storage means for storing the coefficient group obtained from the above, correction data input means for inputting a value for correcting the data of the data storage means, and correction means for correcting the data value of the data storage means with the correction data. A Lagrangian function storage means for approximating a coefficient corresponding to the output signal of the flow rate detection means from the coefficient corrected by the correction means, and an output signal of the flow rate detection means and a data group corrected by the correction means in advance. The gradient calculating means for calculating the coefficient gradient of the Lagrange function storing means, the output signal of the flow rate detecting means, the gradient of the gradient calculating means, and the Lagrange Those having a flow rate calculation means for calculating a flow rate from the Lagrange function stored in the number storage means.

[0009]

According to the present invention, with the above configuration, the correction means corrects the coefficient indicating the relationship between the fluid flow rate and the output signal of the flow rate detection means to the optimum value based on the correction value input from the correction data input means. The corrected coefficient data is approximated by the Lagrangian function, and the output signal of the flow rate detecting means for detecting the fluid flow rate based on the coefficient corresponding to the output signal of the flow rate detecting means at that time and each data corrected by the correcting means The instantaneous flow rate is calculated from the Lagrangian function passing through the points, and the integrated flow rate is obtained.

As described above, since the function showing the non-linear relationship between the fluid flow rate and the output signal of the flow rate detecting means is accurately corrected by the correction data inputting means to obtain the flow rate, the flow rate error can be made extremely small and highly accurate. You can As a result, the integrated value, which is the amount of gas used, can be accurately measured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the same parts as those in FIGS. 4 and 5 are designated by the same reference numerals. FIG. 1 is a block diagram of a flow meter according to an embodiment of the present invention. In FIG. 1, 8 is a flow rate detecting means,
It is composed of a plurality of flow rate detecting means. As an example, 8a is a first flow rate detecting means for measuring a large flow rate region, for example, fluid oscillation is generated using the fluidic oscillating element 3, and the oscillation frequency of the fluid is pressure-voltage using a piezoelectric sensor, a thermistor or the like. Change, heat-resistance change, and 8b is a second flow rate detecting means for measuring a small flow rate region, for example, a flow velocity is obtained by a heat ray sensor. Alternatively, the entire flow rate range can be detected by one flow rate detecting means 8.

Reference numeral 10 denotes a data storage means, which determines a coefficient indicating a relationship between the fluid flow rate and the flow rate detection means 8 from sampling data of a fluid flow rate sampled in a flow rate range to be measured in advance and an output signal of the flow rate detection means 8 at that time. The obtained coefficient is stored as a pair of the coefficient and the output signal of the flow rate detecting means 8. Reference numeral 11 is a correction data inputting means for inputting a value for correcting the variation of the first flow rate detecting means 8a and the variation of the second flow rate detecting means 8b. Or setting device (not shown)
The correction value is transmitted to the correction data inputting means via, for example. 1
A correction unit 2 corrects the coefficient data group stored in the data storage unit 10 with the correction value input to the correction data input unit 11.

Reference numeral 13 is a Lagrangian function storing means, which is a polynomial function approximating a function passing through a data point of a given coefficient. Reference numeral 14 is a gradient calculation means, which is a data storage means 1
The coefficient between the coefficient data stored in 0 and the output signal of the flow rate detection means 8 is used to determine the gradient between the coefficient data. Reference numeral 15 is a switching means, which is the first flow rate detecting means 8a or the second flow rate detecting means 8b.
Switch to determine whether to measure the flow rate with. Reference numeral 16 is a flow rate calculation means, which is an output signal detected by the flow rate detection means 8, a Lagrange function stored in the Lagrange function storage means 13, a data group stored in the data storage means 10, and a gradient calculated by the gradient calculation means 14. From, the instantaneous flow rate at that time is calculated and obtained. Reference numeral 17 denotes an integrated flow rate calculation means, which integrates the obtained flow rates to obtain an integrated value. Reference numeral 18 is a display means for displaying the integrated value and the like.

Next, the operation of the above configuration will be described with reference to FIG. When the gas starts to be used, the gas flow rate is detected by the flow rate detecting means 8
Is detected in the form of a signal such as a voltage signal. At this time, the fluid flow rate and the output signal of the flow rate detecting means have a non-linear characteristic, and the coefficient indicating the relationship between the fluid flow rate and the output signal of the flow rate detecting means 19 at that time has a non-linear characteristic as shown in FIG. Therefore, the relationship between the flow rate and the output signal of the flow rate detection means 8 is measured in advance, several samplings are performed, the coefficient is calculated, and the data is stored in the data storage means 10 via a setting device (not shown).
Transfer to. The setting device is a device for inputting data necessary for flow rate measurement, for example, the flow rate and the output signal of the flow rate detecting means and transmitting the data. The coefficients of the first flow rate detecting means 8a and the second flow rate detecting means 8b have variations, and it is necessary to correct them according to each flow rate detecting means 8. Therefore, the variation correction value is sent to the correction data input means 11 via a setting device or the like. Next, the correction means 12 corrects all the coefficient data stored in the data storage means 10 with the correction values. The corrected coefficient data group is sent to the gradient calculating means 14.

The Lagrange function storage means 13 is sampled and stored in the data storage means 10, and the correction means 12 is used.
The Lagrange function for interpolating and approximating the coefficient between the coefficient data corrected by is stored. On the other hand, the gradient calculating means 14 calculates the gradient value used for the Lagrangian function from the coefficient stored and corrected in the data storing means 10 and the output signal of the flow rate detecting means 19. The above is P1 and P2 in FIG.
Is.

As the Lagrange function δ (F), the following function is used as an example.

[0018]

[Equation 1]

The Lagrange function stored in the Lagrange function storage means 13 this time is a function in the case of n = 1 in the above equation. That is, the non-linear characteristic coefficient shown in FIG.
A linear approximation is performed between the coefficient data corrected in 1. here,
δ (F) is a coefficient corresponding to the output signal F of the flow rate detecting means 8. g (F) indicates a difference between coefficient data stored in the data storage means 19. Fi and Fj are correction values of the output signal of the flow rate detection means stored in the data storage means 19, and show i-th and j-th values. F is an output signal of the flow rate detecting means 8 and shows an arbitrary value. In FIG. 2, the horizontal axis represents the detection signal of the flow rate detecting means 8 and the vertical axis represents the coefficient. The area of the detection signal corresponding to the flow rate range to be measured is arbitrarily divided so that the most accurate approximation can be made. It is assumed that the output signal area is divided into n points. Let each boundary signal be F ₁ ,
F ₂ , ..., Fi, Fj ..., F _n, and coefficient values at that time,
That is, the values given by the ratio between the flow rate and the output signal of the flow rate detecting means 8 are δ (F ₁ ), δ (F ₂ ), ..., δ (F _n ).

The gradient calculating means 14 is the data storing means 10.
The gradient is obtained from the coefficient data stored in the correction data corrected by the correction means 12 and the output signal of the flow rate detection means 8. For example, the gradient between the i-th and j-th divided areas is KF = g (F _i ) /
Given as (Fj-Fi). Therefore, the Lagrange function stored in the Lagrange function storage unit 13 is
δi (F) = KF · (F−Fi).

Next, the instantaneous flow rate Q is calculated by the flow rate calculation means 16.
From the coefficient δ (F) and the output signal F of the flow rate detecting means 8, the relational expression Q = δ (F) · F is obtained. That is, the signal F detected by the flow rate detecting means 8 is substituted into the above equation to obtain the flow rate. The integrated flow rate calculation means 17 adds the instantaneous flow rate Q to obtain the total used integrated flow rate. The display means 18 displays the calculated integrated flow rate value and the like. The above are P3, P4, P5 and P6 in FIG.

As described above, the coefficient data group of the data storage means 10 stored in advance according to the characteristics of the flow rate detecting means 8 using the coefficient having the nonlinear characteristic is the most corrected value inputted through the correction data input means 11. Since the correction is performed so as to reduce the difference and the interpolation approximation is performed using the above-mentioned Lagrangian function, the coefficient for the detected output signal of the flow rate detecting means 8 can be accurately obtained, and the correction process is simple and continuous. The steps can be performed, and as a result, the flow rate can be obtained with high accuracy, and the flow rate measurement such as the integrated flow rate can also be accurately obtained.

Although the present invention has exemplified the fluidic type flow meter for measuring the flow rate of the fluid, the above contents can be applied to other flow meters such as water meters.

[0024]

As described above, the flowmeter of the present invention is
Coefficient data indicating the relationship between the sampled flow rate and the output signal of the flow rate detection means is stored in the data storage means in advance, and a correction value for correcting the variation of the flow rate detection means is input to the correction data input means. The rare data group is corrected, and the gradient value required for the Lagrangian function used in the flow rate calculation unit is calculated from the coefficient data corrected by the correction unit in the gradient calculation unit, and a fluid such as gas is used. When started, the fluid flow rate at that time is detected by the flow rate detecting means, and the instantaneous flow rate is obtained from the coefficient value of the data storing means, the detected output signal, the gradient value of the gradient calculating means and the Lagrangian function stored in the Lagrangian function storing means. Then, the integrated flow rate is calculated to obtain the flow rate. Therefore, the flow rate is calculated with a coefficient that has non-linear characteristics and the variation of the flow rate detection means is corrected. There is an effect that allows the accurate flow measurement with high accuracy can be corrected in connection steplessly.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram of coefficients showing the relationship between the flow rate detecting means of the flowmeter and the flow rate.

FIG. 3 is a flowchart showing the operation of the flow meter.

[Fig. 4] System diagram of a conventional flow meter

FIG. 5 is a characteristic diagram of the control device of the same flow meter.

[Explanation of symbols]

 8 flow rate detection means 10 data storage means 11 correction data input means 12 correction means 13 Lagrange function storage means 14 gradient calculation means 16 flow rate calculation means

Claims (1)

[Claims] 1. A flow rate detecting means for detecting a fluid flow rate, and a data storage means for storing a coefficient group obtained in advance from an output signal of the flow rate detecting means and an output signal of the flow rate detecting means corresponding to the fluid flow rate. Correction data input means for inputting a value for correcting the data in the data storage means, correction means for correcting the data value in the data storage means with the correction data, and the flow rate detection based on the coefficient corrected by the correction means The coefficient gradient of the Lagrangian function storage means is calculated from the Lagrange function storage means that approximates the coefficient corresponding to the output signal of the means, and the output signal of the flow rate detection means and the data group corrected by the correction means in advance. Gradient calculating means,
A flow meter comprising a flow rate calculating means for calculating a flow rate from the output signal of the flow rate detecting means, the gradient of the gradient calculating means and the Lagrange function stored in the Lagrange function storing means.