Method and apparatus for measuring the volume of a flowing liquid

• US 4,969,365 A
• Filed: 12/04/1989
• Issued: 11/13/1990
• Est. Priority Date: 04/24/1987
• Status: Expired due to Fees

• Current Assignee: Ljungmans Industrier AB
• Original Assignee: Ljungmans Industrier AB
• Inventors: Andreasson, Tord, Strigard, Bengt-Olof
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US07/449,509
• Time in Patent Office: 344 Days
• Field of Search: 73/861.03, 73/861.77, 364/510
• US Class Current: 73/861.77
• CPC Class Codes: G01F 15/024 involving digital counting
• CPC Class Codes: G01F 15/0755 involving digital counting
• CPC Class Codes: G01F 3/18 involving two or more cylinders

Abstract

In a method for measuring the volume of a liquid flow through a measuring chamber (2) during a measuring period, a pulse generator (12) is caused to emit a number of pulses corresponding to the volume. In the measurement, the measuring period is divided into a number of measuring intervals. During each measuring interval, the pulses from the pulse generator (12) are detected, each detected pulse is multiplied by a flow correction factor, the corrected pulse values are added to a summation variable, and this summation variable is multiplied by a volume conversion factor for determining the liquid volume. The separate determined liquid volumes are thereafter summed up for all measuring intervals during the measuring period.

A measuring apparatus for measuring the volume of a liquid flow through a measuring chamber (2) has a pulse generator (21, 23) for generating a number of pulses corresponding to the volume, has time base means (33) for dividing the measuring period into measuring intervals, memory means (34) for storing one or more correction factors, pulse-correcting computing means (24, 25) for multiplying each detected pulse by said one or more correction factors, adder means (26, 27) for adding the corrected pulse values, and multiplier means (35) for multiplying the added corrected pulse values by a volume conversion factor.

Claims

1. Method for measuring the volume of a liquid flowing through a measuring chamber (2, 50, 51, 55) during a measuring period, during which a number of pulses corresponding to the volume is generated by a pulse generator (12, 78, 79), which method comprises the steps of dividing the measuring period into a number of measuring intervals, detecting the pulses in each measuring interval and multiplying the detected pulses by a flow correction factor,

characterized by the steps, during each measuring interval, of:

detecting the pulses from the pulse generator (12, 78,

     79), multiplying each separate detected pulse by a flow correction factor which has been selected on the basis of the sum of the corrected pulse values for one or more of the preceding measuring intervals, adding the corrected pulse values to a summation variable and multiplying the value of this summation variable by a volume conversion factor for determining the liquid volume during the measuring interval concerned, and by the step of summing up the liquid volumes for all measuring intervals during the measuring period.

2. Method as claimed in claim 1, characterized by carrying out the step of adding the corrected pulse values to the summation variable, by adding each corrected pulse value to an intermediate storage variable, by determining the integer part of the value of said intermediate storage variable, by subtracting this integer part from the intermediate storage variable, and by adding this integer part to said summation variable.

3. Method as claimed in claim 1, in which the measurement is carried out by means of two pulse generators emitting number of pulses corresponding to the volume when the liquid is flowing in one or the other direction through the measuring chamber, characterized by the steps, during each measuring interval, of detecting the pulses from the first and the second pulse generator, multiplying each separate detected pulse by the flow correction factor, adding the corrected pulse values of the first pulse generator to a first summation variable, adding the corrected pulse values of the second pulse generator to a second summation variable, and subtracting the second summation variable from the first summation variable before the step of multiplying the value of this summation variable by the volume conversion factor.

4. Method as claimed in claim 3, characterized by carrying out the step of adding the corrected pulse values to the second summation variable, by adding each corrected pulse value to a second intermediate storage variable, by determining the integer part of the value of the second intermediate storage variable, by subtracting this integer part from said second intermediate storage variable, and by adding this integer part to said second summation variable.

5. Method as claimed in claim 1, characterized in that the flow correction factor has a value in the range of 0.0000-2.0000.

6. Method as claimed in claim 1, characterized by the steps, during each measuring interval, of integer-dividing the value of the summation variable by a first scale factor if the value of the summation variable is above 0, and by a second scale factor if the value of the summation variable is below 0, setting the summation variable equal to the remainder of the integer division, and multiplying the result of the integer division by the volume conversion factor for determining the liquid volume.

7. Method as claimed in claim 1, characterized by the steps, during each measuring interval, of correcting each detected pulse by a temperature correction factor which has been selected on the basis of the temperature determined during the preceding measuring interval.

8. Method as claimed in claim 1, characterized by the steps, during each measuring interval, of correcting each detected pulse by an aging correction factor which has been selected on the basis of the total liquid volume that has flown through the measuring chamber.