Fluid monitor

• US 4,255,964 A
• Filed: 11/30/1978
• Issued: 03/17/1981
• Est. Priority Date: 11/30/1978
• Status: Expired due to Term

• Current Assignee: The Garrett Corporation
• Original Assignee: The Garrett Corporation
• Inventors: Morison, Rodney
• Primary Examiner(s): YASICH, DANIEL
• Application Number:
  US05/965,369
• Time in Patent Office: 838 Days
• Field of Search: 73/24, 73/597
• US Class Current: 73/24.01
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/22 Details , e.g. general constructional or apparatus details
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects

Abstract

A fluid monitor for determining the percent composition of a fluid mixture of unknown composition when compared to a reference fluid mixture of known composition.

Claims

1. A fluid monitor for monitoring the percent composition of a fluid mixture, said monitor comprising:

a first acoustic chamber having a measurable resonant frequency and containing a reference fluid of known percent composition;

a second acoustic chamber having a measurable resonant frequency and containing a fluid mixture of unknown percent composition;

means for measuring the resonant frequency of said acoustic chambers, said measuring means including;

a first phase locked loop comprising said first acoustic chamber coupled between a voltage controlled oscillator and a phase comparator, said phase comparator being coupled to said voltage controlled oscillator;

a second phase locked loop comprising said second acoustic chamber coupled between a voltage controlled oscillator and a phase comparator, said phase comparator being coupled to said voltage controlled oscillator;

a first transmitting transducer located in said first chamber for sending sound waves through the reference fluid;

a second transmitting transducer located in said second chamber for sending sound waves through the fluid mixture;

said first and second transmitting transducer being driven by a signal from said voltage controlled oscillator;

a first receiving transducer located in said first chamber a predetermined distance from said transmitting transducer for accepting the sound waves and for converting the sound waves into a signal indicative of the reference fluid; and

a second receiving transducer located in said second chamber a predetermined distance from said second transmitting transducer for accepting the sound waves and for converting the sound eaves into a signal indicative of the fluid mixture; and

means for comparing the two resonant frequencies, said comparing means including;

signal processor means coupled to said first and second phase locked loops for comparing the resonant frequency of the reference fluid in said first acoustic chamber with the resonant frequency of the fluid mixture in said second acoustic chamber and determining the percent composition of the fluid mixture.

2. The method of monitoring the percent composition of a fluid mixture comprising the steps of:

(a) providing a first acoustic chamber having mounted therein first and second transducers spaced apart by a predetermined distance;

(b) connecting to said first and second transducers a first phase locked electrical loop adapted to generate between said first and second transducers an acoustic signal having a frequency equal to a resonant frequency of said first acoustic chamber when it contains a reference fluid of known percent composition;

(c) introducing into said first acoustic chamber a reference fluid of known percent composition;

(d) providing a second acoustic chamber having mounted therein third and fourth transducers spaced apart by a predetermined distance;

(e) connecting to said third and fourth transducers a second phase locked electrical loop adapted to generate between said third and fourth transducers an acoustic signal having a frequency equal to a resonant frequency of said second acoustic chamber when it contains a fluid mixture of unknown percent composition;

(f) introducing into said second acoustic chamber a fluid mixture of unknown percent composition;

(g) energizing said first and second phase locked loops; and

(h) determining by direct frequency comparison the difference between the frequencies of the acoustic signals to thereby determine the percent composition of the fluid mixture.

3. The method of claim 2 wherein said connecting step (b) is performed by providing a first voltage controlled oscillator having an input and an output, providing a first phase comparator having an output and a pair of inputs, connecting said output of said first voltage controlled oscillator to said first transducer and to one of said inputs of said first phase comparator, connecting said output of said first phase comparator to said input of said first voltage controlled oscillator, and connecting the other of said inputs of said first phase comparator to said second transducer, and wherein said connecting step (e) is performed by providing a second voltage controlled oscillator having an input and an output, providing a second phase comparator having an output and a pair of inputs, connecting said output of said second voltage controlled oscillator to said third transducer and to one of said inputs of said second phase comparator, connecting said output of said second phase comparator to said input of said second voltage controlled oscillator, and connecting the other of said inputs of said second phase comparator to said fourth transducer.

4. The method of claim 3 wherein said determining step (h) is performed by providing a signal processor having an output and a pair of inputs, connecting one of said signal processor inputs to said output of said first voltage controlled oscillator, connecting the other of said signal processor inputs to said output of said second voltage controlled oscillator, and connecting to said signal processor output means for receiving a signal therefrom and utilizing said signal to indicate the percent composition of the fluid mixture introduced into said second acoustic chamber.

5. A fluid monitor for monitoring the percent composition of a fluid mixture, said fluid monitor comprising:

(a) a first acoustic chamber adapted to receive a reference fluid of known percent composition and, when containing the reference fluid, having a measurable resonant frequency;

(b) a second acoustic chamber adapted to receive a fluid mixture of unknown percent composition and, when containing the fluid mixture, having a measurable resonant frequency;

(c) means, including first phase locked loop means associated with said first acoustic chamber, for electrically generating sound waves within said first acoustic chamber having a frequency equal to said first acoustic chamber resonant frequency,

said sound wave-generating means (c) further including first transmitting transducer means connected to said first phase locked loop means and located in said first chamber for sending sound waves through the reference fluid, and first receiving transducer means located in said first chamber a predetermined distance from said first transmitting transducer means and connected to said first phase locked loop means for accepting sound waves generated through the reference fluid by said first transmitting transducer means and for converting such sound waves into a signal indicative of the reference fluid,

said first phase locked loop means including a first voltage controlled oscillator having an output connected to said first transmitting transducer means, and a first phase comparator interconnected between said first receiving transducer means and said first volage controlled oscillator;

(d) means, including second phase locked loop means associated with said second acoustic chamber, for electrically generating sound waves within said second acoustic chamber having a frequency equal to said second acoustic chamber resonant frequency,

said sound wave-generating means (d) further including second transmitting transducer means connected to said second phase locked loop means and located in said second chamber for sending sound waves through the fluid mixture, and second receiving transducer means located in said second chamber a predetermined distance from said second transmitting transducer means and connected to said second phase locked loop means for accepting sound waves generated through the fluid mixture by said second transmitting transducer means and for converting such sound waves into a signal indicative of the fluid mixture,

said second phase locked loop means including a second voltage controlled oscillator having an output connected to said second transmitting transducer means, and a second phase comparator interconnected between said second receiving transducer means and said second voltage controlled oscillator; and

(e) signal processing means connected between said outputs of said first and second voltage controlled oscillators for measuring and directly comparing the frequencies of said sound waves electrically generated within said first and second acoustic chambers to determine the percent composition of the fluid mixture in said second chamber.

6. Fluid monitoring apparatus for monitoring the percent composition of a fluid mixture, said apparatus comprising:

(a) a housing;

(b) first and second acoustic chambers formed within said housing, each of said first and second acoustic chambers having a pair of opposite ends and a measurable resonant frequency;

said first acoustic chamber having first and second transducers mounted therein on perforated supports possitioned adjacent its opposite ends and spaced apart by a predetermined distance, said first acoustic chamber containing a reference fluid;

said second acoustic chamber having first and second transducers mounted therein on perforated supports positioned adjacent its opposite ends and spaced apart by a predetermined distance, said second acoustic chamber containing a fluid mixture;

(c) a first voltage controlled oscillator having an input and an output, said first oscillator for producing and passing a signal to said first transducer in said first chamber to generate an acoustical signal therefrom which will travel across said first chamber, through the reference fluid, and be received by said second transducer in said first chamber;

(d) a first phase comparator having a first and second input and an output, for determining the phase differential between its input signals, said first input of said first phase comparator being connected to said second transducer in said first chamber and said second input of said first phase comparator being connected to said output from said first voltage controlled oscillator, said output of said first phase comparator being connected to said input of said first voltage controlled oscillator;

(e) a second voltage controlled oscillator having an input and an output, said second oscillator for producing and passing a signal to said first transducer in said second chamber to generate an acoustical signal therefrom which will travel across said second chamber through the fluid mixture, and be received by said second transducer in said second chamber;

(f) a second phase comparator having a first and second input and an output, for determining the phase differential between its input signals, said first input of said second phase comparator being connected to said second transducer in said second chamber and the second input of said second phase comparator being connected to said output from said second voltage controlled oscillator, said output of said second phase comparator being connected to said input of said second voltage controller oscillator; and

(g) signal processing means having a first and second input, said first input of said signal processing means being connected to said output of said first oscillator and said second input of said signal processing means being connected to said output of said second oscillator, said signal processing means for comparing the resonant frequency of said first acoustic chamber containing the reference fluid with the resonant frequency of said second acoustic chamber containing the fluid mixture and calculating the percent composition of the fluid mixture.