Method and apparatus for sensing fluid flow volume to indicate end of filter life
First Claim
1. A method for indicating the operating condition of an impurity filter receiving a variable fluid flow, comprising the steps of:
- generating a pressure differential proportional to the instantaneous rate of fluid flow;
generating an electrical signal which is a function of said pressure differential;
integrating said signal to provide a representation of the total volume of fluid having passed through said filter; and
activating an indicator when the magnitude of said representation has advanced to a value corresponding to a predetermined volume of fluid to be filtered;
wherein said signal generating step is conducted only at spaced intervals during periods when said pressure differential is below a predetermined threshold value and is conducted continuously when said pressure differential is above said predetermined threshold value.
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Accused Products
Abstract
A method and solid-state electronic flowmeter with no moving parts is provided for monitoring instantaneous and/or accumulated fluid flow. A preferred application for the method and flowmeter is the measurement of the total volume of filtered fluid in a fluid treatment system as an indication of end of life for a filter therein. The flowmeter employs a solid-state transducer which senses differential pressure generated by a flow restriction such as a venturi which varies depending on a rate of flow. The transducer output in integrated over time to provide a representation of total fluid flow through the filter. The meter is preferably compact and battery-powered to facilitate ease of installation and use. Battery power is conserved by periodically energizing the transducer during idle periods and by periodically energizing the end of life indicator during and end of life condition.
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Citations
21 Claims
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1. A method for indicating the operating condition of an impurity filter receiving a variable fluid flow, comprising the steps of:
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generating a pressure differential proportional to the instantaneous rate of fluid flow; generating an electrical signal which is a function of said pressure differential; integrating said signal to provide a representation of the total volume of fluid having passed through said filter; and activating an indicator when the magnitude of said representation has advanced to a value corresponding to a predetermined volume of fluid to be filtered; wherein said signal generating step is conducted only at spaced intervals during periods when said pressure differential is below a predetermined threshold value and is conducted continuously when said pressure differential is above said predetermined threshold value. - View Dependent Claims (2, 3)
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4. An apparatus for indicating the operation condition of an impurity filter receiving a variable fluid flow comprising:
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pressure means adapted to contact said fluid flow for generating a pressure differential proportional to the instantaneous rate of flow; A transducer exposed to said pressure differential and generating a first signal proportional to said instantaneous rate of flow; a converter means coupled to said transducer for generating a pulse signal having a frequency proportional to the magnitude of said first signal; counter means coupled to said converter means for storing a count representing a total volume of fluid having flowed through said filter and including means for providing an output signal when said counter has advanced to a predetermined count; annunciator means responsive to said output signal for generating a humanly perceptible signal to indicate end of life of said filter; and first timer means coupled to said transducer for activating said transducer at spaced intervals; and threshold means coupled to said transducer and to said converter means for latching on said transducer and enabling said converter means when said first signal is above a predetermined voltage. - View Dependent Claims (5, 6, 7, 8, 9)
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10. Fluid purification apparatus comprising:
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flow housing means for conducting a variable fluid flow therethrough; impurity filtering means located within said flow housing means for absorbing organic contaminants and for filtering out particulates; pressure means located within said flow housing means and adapted to contact said fluid flow for generating a pressure differential proportional to the instantaneous rate of flow of said fluid; a piezoelectric differential pressure transducer exposed to said pressure differential for generating a voltage signal proportional to said instantaneous rate of flow; voltage to frequency converter means coupled to said transducer for generating a pulse signal having a frequency proportional to the magnitude of said voltage signal; counter means coupled to said converter means for storing a count representing the total volume of fluid having flowed through said filter and including means for producing an output signal when said count has advanced to a predetermined count; annunciator means responsive to said output signal for generating a humanly perceptible signal to indicate end of life of said filter; and first timer means coupled to said transducer for activating said transducer at spaced intervals; and threshold means coupled to said transducer and to said converter means for latching on said transducer and enabling said converter means when said voltage signal is above a predetermined voltage. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An apparatus for monitoring accumulated fluid flow therethrough by sensing and integrating a signal proportional to a differential pressure which is proportional to the rate of fluid flow comprising:
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housing means for conducting a variable fluid flow therethrough; generating means having no moving parts located within said housing means for generating a pressure differential proportional to the instantaneous rate of flow of said fluid through said housing means; first solid-state electronic means for producing a value representing the total volume of fluid having flowed through said housing by integrating said signal over time; second solid-state electronic means for producing an output signal when said value exceeds a predetermined value; indicator means responsive to said output signal for generating a humanly perceptible signal in response to said output signal; timer means for activating said generating means for generating said signal at spaced intervals thereby reducing the energy required to operate the apparatus; and threshold means for continuously enabling said generating means for generating said signal when the instantaneous rate of flow is detected as being above a predetermined value; and battery means within said housing means for supplying electrical power to the apparatus, whereby the apparatus can operate without being externally supplied with electricity; low battery detector means for providing a warning signal to said indicator means when the voltage from said battery is below a specified voltage, and wherein said indicator responds to said warning signal by generating said humanly perceptible signal; and means for causing said humanly perceptible signal to be generated on a periodic, intermittent basis in response to the output signal and to the warning signal, thereby conserving battery power. - View Dependent Claims (18)
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19. An apparatus for monitoring the rate of fluid flow, comprising:
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housing means for conducting a variable fluid flow therethrough; a flow resistance disposed within said housing; a solid-state piezoelectric transducer means having no moving parts located within said housing means for generating a voltage proportional to the instantaneous rate of flow of said fluid through said housing means; solid-state electronic means for producing a value representing the rate of fluid flowing through said housing; timer means for activating said piezoelectric means at spaced intervals thereby reducing the energy required to operate the apparatus; and threshold means for continuously enabling said piezoelectric means when the instantaneous rate of flow is detected as being above a predetermined value. - View Dependent Claims (20, 21)
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Specification