Temperature compensating system

• US 3,905,229 A
• Filed: 09/26/1973
• Issued: 09/16/1975
• Est. Priority Date: 10/09/1972
• Status: Expired due to Term

• Current Assignee: Masaaki Togo, Nobuo Takeuchi
• Original Assignee: Masaaki Togo, Nobuo Takeuchi
• Inventors: Togo, Masaaki, Takeuchi, Nobuo
• Primary Examiner(s): Goldstein, Herbert
• Application Number:
  US05/401,066
• Time in Patent Office: 720 Days
• Field of Search: 73/194E,194M,231M,233,362A,362R 235/151.34
• US Class Current: 73/861.03
• CPC Class Codes: G01D 3/0365 the undesired influence being measured using a separate sensor, which produces an influence related signal
• CPC Class Codes: G01F 15/024 involving digital counting

Abstract

A flow meter system including a temperature sensitive transducer is provided for referring to a selected reference base or standard temperature flow measurements made of fluids at temperatures encountered in the process industries, which fluids have temperature coefficients of volume expansion producing changes in volume with changes in temperature. The system also provides a correction factor for a non-linear characteristic of the transducer.

Claims

1. In a system for measuring a quantity in terms of a pulse signal corresponding to the measurement, which measurement is subject to error due to environmental changes to which said quantity is exposed, a compensating system to pRoduce a conversion coefficient for referring said measurement to a reference base or standard environmental condition, said compensating system including a transducer having a non-linear response characteristic for providing an output in accordance with said changes, a converter responsive to said transducer for producing an electrical signal in accordance with said changes, said converter including means having a non-linear response characteristic similar to said non-linear response characteristic of said transducer and connected to oppose and neutralize the effect of the non-linearity of said transducer whereby said electrical signal is free from the said non-linear characteristic of said transducer, an analog-to-digital converter to convert said electrical signal into a corresponding digital value, said digital value being representative of said conversion coefficient and means to multiply said pulse signal by said digital value to compensate said pulse signal thereby to provide an output pulse signal that is referred to said base or standard environmental condition, said transducer being a temperature-sensitive resistance, said first-mentioned converter including a bridge circuit having said temperature-sensitive resistance connected in one arm thereof, means including a series resistor for connecting a source of voltage across the energizing terminals of said bridge, an operational amplifier having an inverting input and a non-inverting input and an output, means connecting said inverting input of said operational amplifier to an output junction of said bridge which is directly connected to said temperature-sensitive resistance, means connecting an opposing output junction of said bridge to said non-inverting input of said operational amplifier, and an output circuit connected to the output of said operational amplifier to produce a voltage representative of the output from said operational amplifier, said output circuit being connected to said voltage source through said series resistor.

2. In a system as specified in claim 1 and wherein the said opposing output junction of said bridge comprises the movable contact of an adjustable potentiometer resistance.

3. In a system as specified in claim 1 and wherein said temperature-sensitive resistance is a platinum temperaturesensitive resistance element.

4. In a system as specified in claim 1 including a first constant current source connected between said first mentioned bridge output junction, and said series resistor, and a second constant current source connected between said mentioned bridge output junction and said series resistor.

5. In a system for measuring a quantity in terms of a pulse signal corresponding to the measurement, which measurement is subject to error due to environmental changes to which said quantity is exposed, a compensating system to produce a conversion coefficient for referring said measurement to a reference base or standard environmental condition, said compensating system including a transducer having a non-linear response characteristic for providing an output in accordance with said changes, a converter responsive to said transducer for producing an electrical signal in accordance with said changes, said converter including means having a non-linear response characteristic similar to said non-linear response characteristic of said transducer and connected to oppose and neutralize the effect of the non-linearity of said transducer whereby said electrical signal is free from the said non-linear characteristic of said transducer, an analog-to-digital converter to convert said electrical signal into a corresponding digital value, said digital value being representative of said conversion coefficient and means to multiply said pulse signal by said digital value to compensate said pulse signal thereby to provide an output pulse signal that is referred to said base or standard environmental condition, said transducer being a temperature-sensitive resistance, said first-mentioned conveRter including a bridge circuit having said temperature-sensitive resistance in one arm thereof, connecting means for connecting a source of voltage across the energizing terminals of said bridge, an operational amplifier having an inverting input and a non-inverting input and an output, means connecting said inverting input of said operational amplifier to an output junction of said bridge which is directly connected to said temperature-sensitive resistance, means connecting an opposing junction of said bridge to the non-inverting input of said operational amplifier, a first constant current source connected between said first-mentioned bridge output junction and said connecting means, a second constant current source connected between said second-mentioned bridge output junction and said connecting means, means for controlling said first and second mentioned constant current sources including a resistor connected to said connecting means, and an output circuit connected to the output of said operational amplifier to produce a voltage representative of the output of said operational amplifier, said output circuit being connected to said connecting means through said resistor.

6. In a system as specified in claim 5 and wherein the said opposing output junction of said bridge comprises the movable contact of an adjustable potentiometer resistance.

7. In a system as specified in claim 5 and wherein said temperature sensitive resistance is a platinum temperaturesensitive resistance element.