Instrumental error compensation circuit for flow meter

• US 4,581,946 A
• Filed: 06/17/1983
• Issued: 04/15/1986
• Est. Priority Date: 06/21/1982
• Status: Expired due to Term

• Current Assignee: Masahiro Kanayama
• Original Assignee: Masahiro Kanayama
• Inventors: Kanayama, Masahiro
• Primary Examiner(s): Goldstein, Herbert
• Application Number:
  US06/505,525
• Time in Patent Office: 1,033 Days
• Field of Search: 73/861.02, 73/861.03, 73/861.77, 73/861.78, 73/861.81, 73/861.83, 364/510, 377/21
• US Class Current: 73/861.77
• CPC Class Codes: G01F 1/125 with electric, electro-mechanical or electronic means
• CPC Class Codes: G01F 15/00 Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
• CPC Class Codes: G01F 15/024 involving digital counting

Abstract

An instrumental error compensation circuit for a flow meter is disclosed in which a flow rate calculated from an output signal of the flow meter is identified with respect to a plurality of predetermined sections of flow rates. Flow rate compensation coefficients are calculated by linear interpolation on the basis of actually measured data which are obtained in advance in accordance with instrumental errors of the flow meter. Actual flow rates of a fluid are measured with the instrumental errors of the flow meter compensated for by the calculated coefficients.

Claims

1. A circuit for compensating for an instrumental error of a flow meter which generates a pulse signal having a frequency proportional to a flow rate, said circuit comprising:

pulse distributor means for generating two different pulse signals in response to the pulse signal output from the flow meter, said two pulse signals having a predetermined frequency ratio to each other;

flow rate calculator means for calculating an instantaneous flow rate based on the frequency of the outer signal of the flow meter and generating an output signal indicative of said instantaneous flow rate;

flow rate section identifier means for identifying, in response to the output signal of the flow rate calculator means, specific one of predetermined flow rate sections to which the calculated instantaneous flow rate belongs, and generating a signal indicative of the identified section;

compensation constant memory means for storing in advance a plurality of compensation constants necessary for calculating an instrumental error of the flow meter for each of the sections, selecting specific one of the compensation constants in response to the output signal of the identifier means, and generating a signal indicative of said compensation constant;

compensation constant calculate and write circuit means for calculating a compensation coefficient in response to the output signal of the compensation constant memory means by performing interpolation corresponding to a flow rate, and generating a signal indicative of the compensation coefficient;

compensation amount calculator means for calculating an amount of compensation corresponding to the output signal of the compensation constant calculate and write circuit means in synchronism with one of the pulse signals output from the pulse distributor means, and generating a signal indicative of said amount of compensation, said compensation constant memory means, in response to an output of said flow rate section identifier means, producing a compensation value associated with the input, said compensation value being loaded into said compensation amount calculator means such that each time a pulse signal is delivered from said pulse distributing means to said compensation amount calculator means, said compensation amount calculator means calculates a compensation value based on the output data of said compensation constant memory means;

adder means for adding up the output signals of the compensation amount calculator means, and every time the sum reaches a predetermined numerical value, generating an overflow pulse signal as a compensated flow rate pulse;

output sync circuit means for sumchronizing the output pulse signal of the adder means to said other output signal of the pulse distributor means to generate a sync signal;

a write circuit means for entering data in said flow rate section identifier means and data in said compensation constant memory means corresponding to outputs of said flow rate section identifier means; and

temporary flow rate section means for temporarily storing said entered data such that said data is received by said compensation constant calculate and write circuit means via said temporary flow rate sections means, whereby said compensation constant calculate and write circuit means performs said calculations.

2. A circuit as claimed in claim 1, in which the ratio in frequency of said other output pulse signal of the pulse distributor means fed to the output sync circuit means to said one output pulse signal fed to the compensation amount calculator means is 2:

1.

3. A circuit as claimed in claim 1, in which the output sync circuit means comprises an up-down counter which accumulates the overflow pulse signals output from the adder means and generates a logical "1" output signal only when a count is not zero, an AND gate to which an output signal of said up-down counter and said other output signal of the pulse distributor means are supplied, and a circuit for delivering an output signal of said AND gate to a subtraction input terminal of the up-down counter.

4. A circuit as claimed in claim 1, further comprising data input means for entering and temporarily storing instrumental error data on the flow meter for each of actually measured flow rates, calculating compensation values for the individual flow rate sections, and loading the calculated values in the identifier means.

5. A circuit as claimed in claim 4, in which the data input means comprises keys for writing data.

6. A circuit as claimed in claim 4, in which the data input means comprises a read only memory.