Method and apparatus for sensing fluid flow volume to indicate end of filter life

An apparatus for indicating the operation condition of an impurity filter receiving a variable fluid flow comprising:

• 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.

Fluid purification apparatus comprising:

• 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.

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:

• 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.

An apparatus for monitoring the rate of fluid flow, comprising:

• 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.