JPS586417A - Method and device for compensation of device error of pulse generation type flow meter - Google Patents

Abstract

PURPOSE:To realize the simple and highly accurate compensation of a device error over the entire flow rate region, by converting the pulse produced from a flow meter into its proportional current, calculating the device error corresponding to said current and compensating the pulse based on the device error. CONSTITUTION:The pulse produced from a flow rate meter is converted into its proportional current through a frequency-current converter 2. Then a device error corresponding to said current is calculated, and the pulse is compensated based on the device error. For instance, a pulse P0 produced from a flow rate meter 1 is fed to a frequency-current converter 2 as well as to a device error compensator 5. The converter 2 converts the pulse P0 into a current I1 which is proportional to the pulse P0 to display the current to an instantaneous flow rate indicator 3 and also to lead the current to an operator 4. The device error is obtained from a relation between a flow rate factor R and a device error E which are previously stored in the operator 4. This device error is fed to the compensator 5 to obtain a pulse P1. This pulse P1 is fed to a pulse counter 6 to be integrated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and device for correcting instrumental error in a pulse-generating flowmeter, and more specifically, the present invention relates to a method and device for correcting instrumental error in a pulse-generating flowmeter, and more specifically, the present invention relates to a method and device for correcting instrumental error in a flowmeter such as a positive displacement flowmeter or a turbine flowmeter, in which a signal is extracted as a pulse. The present invention relates to a method and apparatus for reducing the flow rate from a low flow rate range to a high flow rate range as much as possible.

In general, for flow needles that measure the flow rate of gases and liquids, there is a difference between the measured value (the flowmeter reading) and the actual value (the value measured by a standard meter). That's what it means. In actual flow measurement, this instrumental error must be corrected to obtain a more accurate flow rate. Conventionally, the method for correcting this instrumental error has been to use a pulse converter called SKE-2 to convert the input signal to a constant value. By multiplying the output signal, the output signal was increased or decreased proportionally. Instrument error correction using this method can only use the gradient in the correlation between flow rate and pulse value, but has the disadvantage that it is not possible to reduce the instrumental error over the entire flow range when a gradient occurs in the low flow rate region and high flow rate region. Ta.

The present invention aims to eliminate such drawbacks.

That is, the present invention converts the pulse Po emitted from the pulse generating flowmeter into a current proportional to the pulse Po using a frequency-current converter. and then calculating an instrumental error E corresponding to this current X, and correcting the pulse po by this instrumental error 1. , a frequency-to-current converter that inputs a pulse P transmitted from a pulse-generating flowmeter and generates a current 1 proportional to the pulse P; inputs the current 1 and converts the current 1 and the maximum flow rate. An instrumental error correction device for a pulse generation type flowmeter is provided, which comprises an arithmetic unit that calculates an instrumental error F from a ratio R1 of M proportional to , and an instrumental error corrector that corrects the pulse Po using the calculated instrumental error I. This is what we provide.

The method and apparatus of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a block diagram showing an example of an apparatus for carrying out the method of the present invention.

First, a pulse r·(number of times/?F/) transmitted from the pulse generation type flowmeter 1 is inputted to the frequency-current converter 2 and also inputted to the instrumental error corrector 5. This frequency-current converter 2 converts the input pulse P into a current x1 proportional to the pulse r, using the equation k1=klP, and displays this on the instantaneous flow rate indicator 5, and at the same time Lead to 4. This calculator 4 stores in advance the relationship between the flow rate R and the instrumental error 1. Here, instrumental abuse is defined as follows.

In addition, the flow rate R is the ratio between the flow IQ and the maximum flow rate Qmax, R
- Q / Q engineering
, p, , are proportional to x, and these pulses P.

Baa! Also, the current flow from frequency-to-current converter 2, power, &
xQmax -kg Pmax-￥Ig-4==nikum
aX, and from this the flow rate R is ” = Q / Q
Ma! - It becomes engineering/engineering wax. In other words, the flow rate R is expressed as the ratio of eff and maX.

Therefore, the relationship between the flow rate R and the instrumental error 1 is defined as -f(ψ-?(6)-m-)1DB-)OR"+...
・If it is defined as a function, the frequency-current converter 2
The flow rate R1 is determined by the current l1 input from 1, and the instrumental error E is determined as -a-)bRI+aR1''-)--.

Subsequently, the instrumental error calculated by the calculator 4 is input to the instrumental error corrector 5. The instrumental error corrector 5 uses this instrumental error X to correct the pulse P· input from the flowmeter 1. Although various relational expressions can be considered for this correction, the corrected pulse P is usually calculated by the equation PIIIP·(1). Various types of instrumental error corrector 5 are conceivable for performing such correction, and a gate circuit or a circuit having a structure as shown in FIG. 2 can be used. 2nd v! J is a schematic diagram showing an example of the structure of an instrumental error corrector.

The current x1 from the frequency-current converter 2 is input to an automatically balanced current indicator 7. This indicator 7 is of a type that moves left and right, and a contact point is provided at the tip of the pointer. On the other hand, the contacts on the other side are long in the direction of movement of the pointer, and are weighed to an appropriate number. Connect relay 8 to the circuit formed by the pointer and the opposing contacts. In this case, the relay should be a transistor, diode, etc. Further, the contact may be a non-vibration contact type contact. A scaler 9 circuit with various numerical values is connected to the contacts on the relay side, so that when the relay is closed and the contacts are connected, the scaler has the corresponding magnification. If an instrumental error corrector having such a structure is used, it is possible to perform appropriate instrumental error correction according to the input electric current 1.

By inputting the pulse XP obtained by performing the instrumental error correction as described above to the pulse counter 6 and integrating it, the flow rate of the fluid can be measured with high precision.

As explained above, by using the method and apparatus of the present invention, instrumental errors can be easily and highly accurately corrected over a range from low flow rates to high flow rates. Therefore, even if the flow rate needle deteriorates or the machining accuracy is poor and the tolerance range is exceeded, proper instrumental error correction can be performed without replacing the flow rate needle or its parts. I can do it.

Therefore, the method and apparatus of the present invention can be widely and effectively used throughout the flow measurement process.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of electrical equipment for implementing the method of the present invention, and FIG. 2 is a schematic diagram showing an example of the structure of an instrumental error corrector. DESCRIPTION OF SYMBOLS 1...Pulse-generating sitting type flowmeter, 2...Frequency-current converter, 5...Indicator for flowing between legs, 4...Arithmetic unit. 5...Instrumental error corrector, 6...Pulse counter. 7... Automatic balancing current indicator, 8... Relay. 9...Scaleer-0 Patent source: Idemitsu Kosan Co., Ltd.

Claims (2)

[Claims] (1) Pulse P transmitted from a pulse generating flowmeter
is converted into a current factor i proportional to the pulse P by a frequency-to-current converter, and then an instrumental error I corresponding to this current factor 1 is obtained.
A method for correcting an instrumental error in a pulse generation type flowmeter, characterized in that the pulse P is corrected by calculating the instrumental error value. (2) Pulse P transmitted from the pulse generating flow rate needle,
A frequency-to-current converter which inputs the current 1 and generates a current 1 proportional to the pulse P, and a ratio R between the current 1 and the current 1 which is proportional to the maximum flow rate, and χ. An instrumental error correction device for a pulse-generating flowmeter, which comprises an arithmetic unit that calculates an instrumental error from X and an instrumental error corrector that corrects the pulse P by the calculated instrumental error X.