Incrementally adjustable electronic expansion valve

A refrigeration system including a compressor, a condenser, and an evaporator, and including an electronic refrigerant expansion valve comprising:

• an inlet means for receiving refrigerant from the condenser;
• an outlet means for discharging refrigerant to the evaporator;
• an orifice means, connected between the inlet means and the outlet means, said orifice means including a generally cylindrical orifice assembly having a top end which is capped, a bottom end which is open and connected to receive refrigerant from the inlet means, and at least one orifice opening, located between the capped end and the open end of said assembly, for controlling refrigerant flow between the inlet means and the outlet means;
• a sleeve member which slides over the orifice means to adjust the size of the orifice opening depending on the position of the sleeve member relative to the orifice means;
• a first annular sealing means, located in an annular recess in the orifice assembly above the orifice opening and positioned between the sleeve member and the orifice assembly, for substantially preventing refrigerant flow across said first annular sealing means when the sleeve member is in a fully closed position covering over the orifice opening in the orifice assembly;
• a second annular sealing means, located in another annular recess in the orifice assembly below the orifice opening and positioned between the sleeve member and the orifice assembly when the sleeve member is in its fully closed position, for substantially preventing refrigerant flow across said second annular sealing means when the sleeve member is in its fully closed position;
• a spring biased follower means, positioned to follow movements of the sleeve member, for covering over the second annular sealing means to hold the second annular sealing means in its annular recess when the sleeve member moves out of contact with the second annular sealing means and for partially uncovering the second annular sealing means when the sleeve member moves into contact with the second annular sealing means;
• and
• motor means, operatively connected to the sleeve member, for incrementally adjusting the position of the sleeve member relative to the orifice means in response to electronic digital control signals received by said motor means.