Miniature passive thermal control valve for mixing or splitting single-phase fluid with adjustable thermal actuator

A passive thermal control valve for controlling flow of a system fluid, the control valve comprising:

• a thermal actuator comprising:
• an actuator body having an inner bore;
• a stop engaging the actuator body;
• a cylinder received within the inner bore of the actuator body, the cylinder having a cylinder bore open at one end;
• an actuator spring within the inner bore of the actuator body biasing the cylinder towards the stop;
• an actuator rod having a first end and a second end, the actuator rod at least partially received within the cylinder, at least a portion of the actuator rod and the rod second end allowed to extend through the open end of the cylinder bore;
• a bellows within the cylinder extending over a portion of the rod, a bellows first end sealingly affixed to a first end of the rod and a bellows second end affixed to a top flange of the cylinder;
• and
• a thermal fluid contained within the cylinder on the outside of the bellows;
• a valve body connected to the actuator body;
• and
• a valve spool movably positioned within the valve body.

A method for passively controlling flow of a system fluid to a first outlet port, a second outlet port, or to first and second outlet ports of a thermal control valve depending on the temperature of the system fluid, with the thermal control valve comprising an actuator body, a cylinder within an inner bore of the actuator body, an actuator rod at least partially received within the cylinder and a thermal fluid contained within the cylinder, the thermal control valve having a system fluid temperature control range, the method comprising the steps of:

• passively adjusting the flow of the system fluid to the first outlet port, the second outlet port, or the first and second outlet ports as the system fluid temperature changes within the temperature control range by moving the actuator rod relative to the cylinder and the actuator body;
• passively controlling the flow of the system fluid through the first outlet port for system fluid temperatures below the temperature control range;
• and
• passively controlling the flow of the system fluid through the second outlet port for system fluid temperatures above the temperature control range by moving the cylinder relative to the actuator rod and actuator body.