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    help-Working Principle of Electronic Expansion Valve



    Hi every body ,hope you all will be in sound health and enjoying all in your own way.
    I want to know one point regarding working of electronic expansion valve .
    A thermistor conveys superheat condition through a circuit to heater with negative temperature resistance coefficient. My question is that how does heater operate needle valve to allow more or less refrigerant to evaporator?
    Thanks in advance



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    Re: help-Working Principle of Electronic Expansion Valve


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    Re: help-Working Principle of Electronic Expansion Valve

    Thank you sir for your kind reply but my point is still not clear.
    The type of expansion valve in link you posted above is different to which I asked.
    Please see the following link and read the electronic expansion valve section from where my question originated.
    http://www.google.com.pk/url?sa=t&rc...,d.bGE&cad=rja
    Last edited by pakblogger2012; 03-07-2013 at 09:37 PM.

  4. #4
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    Re: help-Working Principle of Electronic Expansion Valve

    The heater probably heats a fluid which will then expand and move the valve needle.

    Never seen one myself as now-a-days we tends to use electric stepper motors to drive the valve up and down.
    Brian - Newton Abbot, Devon, UK
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    Re: help-Working Principle of Electronic Expansion Valve

    Quote Originally Posted by pakblogger2012 View Post
    My question is that how does heater operate needle valve to allow more or less refrigerant to evaporator?
    Thanks in advance
    This is done by electrochemical actuator. It is consisted of heater around thermal actuator. Current of heater is regulated through thermistor which senses evaporator exit temperature.

    Thermal actuator:
    diagram.jpg

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    Re: help-Working Principle of Electronic Expansion Valve

    Thank you nike123,but one thing is still not clear .
    In figure you posted above ,it seems that at higher current actuator will give narrow path for refrigerant flow but actually opposite happens ,above figure does not match actual working of electonic valve.
    your guidance please

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    Re: help-Working Principle of Electronic Expansion Valve

    This is principle of function of piston in valve. Opposite action can be done by spring in assembly. Momentary, I don't have any picture of actual valve.
    Last edited by nike123; 04-07-2013 at 06:27 AM.

  8. #8
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    Re: help-Working Principle of Electronic Expansion Valve

    Quote Originally Posted by pakblogger2012 View Post
    Thank you nike123,but one thing is still not clear .
    In figure you posted above ,it seems that at higher current actuator will give narrow path for refrigerant flow but actually opposite happens ,above figure does not match actual working of electonic valve.
    your guidance please
    Dear pak,
    As per your catalogue, high current will open the valve widely(not narrow path). Anyway thanks you and nike, giving the information about these type EEEV.my experience was only related with stepper motor.

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