Three-way modulating valve for temperature control

A system for changing the temperature of a first fluid to meet a desired temperature comprising:

• a fluid supply for said first fluid, said fluid supply for said first fluid passing through a heat exchanger, and a temperature sensor for said first fluid to sense a temperature of said first fluid downstream of said heat exchanger;
• a supply for a second fluid to change a temperature of said first fluid, said supply for said second fluid passing through said heat exchanger;
• a three-way valve positioned upstream of said heat exchanger on said supply for said second fluid, and controlling a flow rate of said second fluid diverted into a bypass line compared to a flow rate of said second fluid directed through said heat exchanger, with said three-way valve controlled by a control in response to feedback from said temperature sensor;
• said three-way valve changes the respective flow rates delivered into said bypass line and through said heat exchanger in a non-linear manner with a change in valve position;
• a control to control a position of said three-way valve, and a sensor for sensing a temperature of the first fluid downstream of the heat exchanger, said sensor communicating the temperature to said control said control positioning the valve such that the non-linear change in said flow rate delivered into said bypass line and through said heat exchanger result in a temperature change in said first fluid that is substantially linear;
• said three-way valve including a rotating spool with a first window delivering said second fluid to a first outlet leading to said bypass line and a second window delivering said second fluid into a second outlet leading to said heat exchanger, and said spool having an interior chamber to receive said second fluid from said supply for the second fluid and communicate the second fluid to the first and second windows;
• said control changing a circumferential position of the valve to achieve said non-linear flow rates;
• and
• said supply for the second fluid connected into said interior chamber by an end surface, and said first and second windows being formed in side walls of said rotating spool, and there being a valve housing surrounding said valve, and including said first outlet and said second outlet, such that said first outlet and said second outlet communicate with said interior chamber through the first and second windows.