Thermostatic valve device having non-linear flow characteristics

A thermally responsive fluid flow control valve device for elimination of temperature fluctuations in the fluid during initial opening operation comprising:

• a stationary valve member having an annular valve seat portion forming a fluid port,
• a movable valve member having a closure portion engageable with the annular valve seat portion to close the fluid port, the movable valve member being movable to move the closure portion toward and away from the valve seat portion of the stationary valve member,
• the stationary valve member having an annular flange encompassing the valve seat portion and forming a recess within which the annular valve seat portion is located and within which the closure portion of the movable valve member is movable, the annular flange having a sloping part, initial movement of the movable valve member with respect to the stationary valve member thus creating a small fluid flow passage between the flange and the movable valve member, and increased movement of the closure portion of the movable valve member adjacent the annular flange being non-linear in magnitude with respect to the area of the fluid flow passage created between the annular flange and the movable valve member,
• thermally responsive actuator means,
• means joining the thermally responsive actuator means to the movable valve member for movement thereof.