JPH0719917A - Flowmeter - Google Patents

Abstract

PURPOSE:To correct the fluctuation of a flow rate detecting sensor for measuring the flow rate of gas or liquid, and perform a highly precise flow rate calculation. CONSTITUTION:A coefficient data group determined from the data obtained by a fluid flow rate and the output signal of a flow rate detecting means 8 are preliminarily stored in a data storing means 9, and the data for correcting the dispersion of the flow rate detecting means 8 is inputted to a correction value input means 10. Further, a correcting means 11 corrects the coefficient data group stored in the data storage means 9 with a correction value. A flow rate arithmetic means 12 interpolates and approximates the nonlinear characteristic of a coefficient showing the relationship between a fluid flow rate Q and the flow rate detecting means 8 from the output signal detected by the flow rate detecting means 8 and the corrected data group of the coefficient data of the data storage means 9 to determine the flow rate.

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 calculation function with higher accuracy than the output signal of the flow rate 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 absorbing variations in flow rate detecting means and performing accurate flow rate calculation from an output signal.

[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. And a correction value input means for inputting a value for correcting the data of the data storage means, and a correction means for correcting the data value of the data storage means with the correction data. When,
The flow rate calculation means calculates a flow rate from the output signal of the flow rate detection means and the coefficient data group corrected by the correction means.

[0009]

According to the present invention, with the above structure, the correction means corrects the variation of 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 value input means. The instantaneous flow rate is calculated by the flow rate calculation means from the corrected coefficient data and the output signal of the flow rate detection means, and the integrated flow rate is further obtained.

As described above, since the rare number variation 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 value input means to obtain the flow rate, the flow rate error is extremely small and the accuracy is high. It can be stopped. As a result, the integrated value, which is the amount of gas used, can be accurately measured.

[0011]

DETAILED 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, reference numeral 8 is a flow rate detecting means, which causes fluid oscillation by using, for example, a fluidic oscillation element 3, and determines the oscillation frequency of the fluid by a piezoelectric sensor,
It is detected as a pressure-voltage change or a heat-resistance change using a thermistor or the like, or the flow velocity is obtained by a hot wire type sensor.

Reference numeral 9 denotes a data storage means, and a coefficient indicating the relationship between the fluid flow rate and the flow rate detection means 8 is obtained from sampling data of the fluid flow rate Q sampled in advance in the flow rate range to be measured and the output signal of the flow rate detection means 8 at that time. , And the output signal of the flow rate detecting means 8 are stored as a pair. 10
Is a correction value input means to which a value for correcting the variation of the flow rate detection means 8 is input. Alternatively, the correction value is transmitted to the correction value input means via a setter (not shown) or the like. A correction unit 11 corrects the coefficient data group stored in the data storage unit 9 with the correction value input to the correction value input unit 10.

Reference numeral 12 denotes a flow rate calculation means, which calculates and calculates the instantaneous flow rate at that time from the output signal detected by the flow rate detection means 8 and the coefficient data group corrected by the correction means 11. Thirteen
Is an integrated flow rate calculation means for integrating the obtained flow rates to obtain an integrated value. Reference numeral 14 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 non-linear characteristics, and the coefficient δ (F) indicating the relationship between the fluid flow rate Q and the output signal of the flow rate detecting means 8 at that time is nonlinear as shown in FIG. It has various characteristics. Therefore, the relationship between the flow rate and the output signal of the flow rate detecting means 8 is measured in advance, several samplings are performed,
The coefficient is obtained and transferred to the data storage means 9 via, for example, a setter (not shown). 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 coefficient δ (F) indicating the relationship between the fluid flow rate Q and the output signal of the flow rate detecting means 8 varies, and it is necessary to correct it according to the flow rate detecting means 8 attached to each flow meter. Therefore, a correction value for correcting the variation of the flow rate detection means attached to the correction value input means 10 is sent via a setting device or the like. Next, the correction means 11 corrects all the coefficient data stored in the data storage means 9 with the correction values. The corrected coefficient data group is sent to the flow rate calculation means 12. The above is P1, P2, and P3 in FIG.

The coefficient δ (F) corresponding to the output signal of the arbitrary flow rate detecting means 8 having the non-linear characteristic shown in FIG. 2 is obtained by linear approximation between the coefficient data corrected by the correcting means 11. here,
δ (F) is a coefficient corresponding to the output signal F of the flow rate detecting means 8. F is an output signal of the flow rate detecting means 8 and shows an arbitrary value.
Fi and Fj are the values of the output signal of the flow rate detection means stored in the data storage means 9, and indicate the i-th and j-th values.

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. The respective boundary signals are F ₁ , F ₂ , ... F
i, Fj · ·, and F _n, the coefficient value at that time, i.e., flow rate and a value given by the ratio of the output signal of the flow rate detecting unit 8 [delta]
(F ₁ ), δ (F ₂ ), ..., δ (F _n ).

Next, the instantaneous flow rate Q is calculated by the flow rate calculating means 12.
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 13 adds the instantaneous flow rate Q to obtain the total used flow rate. The display means 14 displays the calculated integrated flow rate value and the like. The above are P4, P5, P6, and P7 in FIG.

As described above, the coefficient data group of the data storage means 9 stored in advance is matched with the characteristic of the flow rate detecting means 8 whose coefficient shows a non-linear characteristic, and the correction value input through the correction value input means 10 has the most instrumental error. It is corrected so that it becomes smaller, and the coefficient between the sampled points is approximated by a straight line.
The coefficient for the detected output signal of the flow rate detecting means 8 can be accurately obtained, and the correction process can be performed easily and continuously without any step. As a result, the flow rate can be obtained with high accuracy, and the flow rate such as the integrated flow rate can be measured. Accurately required.

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

[0021]

As described above, the flowmeter of the present invention is
The coefficient data indicating the relationship between the sampled flow rate and the output signal of the flow rate detecting means is stored in advance in the data storage means, and the correction value for correcting the variation of the flow rate detecting means is input to the correction value input means. When the coefficient data group is corrected and the coefficient data corrected by the correction means and the fluid such as gas are started to be used, the flow rate detection means detects the fluid flow rate at that time, the instantaneous flow rate is calculated, and then the integrated flow rate is calculated. Since the flow rate is calculated, the flow rate is calculated using a coefficient that has a non-linear characteristic and the variation of the flow rate detecting means is corrected, and therefore, there is an effect that the flow rate can be easily and continuously corrected and the flow rate can be accurately measured with high accuracy.

[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 9 data storage means 10 correction value input means 11 correction means 12 flow rate calculation means

Front page continuation (72) Inventor Koichi Ueki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Koichi Takemura 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

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. A correction value input means for inputting a value for correcting the data of the data storage means, a correction means for correcting the data value of the data storage means with the correction data, an output signal of the flow rate detection means and the correction means. A flow meter comprising a flow rate calculation means for calculating a flow rate from a corrected coefficient data group.