Multi-thermostat engine cooling system

Abstract

A cooling system for an engine is disclosed. The cooling system may have a pump driven by the engine to pressurize coolant, a single heat exchanger configured to cool pressurized coolant, and an aftercooler configured to transfer heat from air entering the engine to pressurized coolant. The cooling system may also have a multi-thermostat arrangement configured to always direct at least a portion of the pressurized coolant from the pump through the aftercooler, and selectively direct pressurized coolant from the pump through the single heat exchanger. The multi-thermostat arrangement may also be configured to selectively mix pressurized coolant from the aftercooler with a remaining portion of the pressurized coolant from the pump to form a coolant mixture, and to selectively direct the coolant mixture through the engine or around the engine.

1 . A cooling system for an engine, comprising:
 a pump driven by the engine to pressurize coolant;   a single heat exchanger configured to cool pressurized coolant;   an aftercooler configured to transfer heat from air entering the engine to pressurized coolant; and   a multi-thermostat arrangement configured to:
 always direct at least a portion of the pressurized coolant from the pump through the aftercooler; 
 selectively direct pressurized coolant from the pump through the single heat exchanger; 
 selectively mix pressurized coolant from the aftercooler with a remaining portion of the pressurized coolant from the pump to form a coolant mixture; and 
 selectively direct the coolant mixture through the engine or around the engine. 
   
     
     
         2 . The cooling system of  claim 1 , wherein the multi-thermostat arrangement includes:
 a first thermostat located directly upstream of the single heat exchanger and the aftercooler; and   a second thermostat located directly downstream of the aftercooler and the pump, and upstream of the engine.   
     
     
         3 . The cooling system of  claim 2 , wherein the first thermostat includes a valve element movable between a first end-position at which pressurized coolant from the pump flows through the single heat exchanger to the aftercooler, toward a second end-position at which pressurized coolant from the pump flows first through the single heat exchanger and then through the aftercooler. 
     
     
         4 . The cooling system of  claim 2 , wherein the second thermostat is a four-way thermostat configured to receive pressurized coolant directly from the pump and directly from the aftercooler, and to discharge pressurized coolant directly to the engine and to the pump. 
     
     
         5 . The cooling system of  claim 4 , further including a third thermostat located directly downstream of the engine and directly upstream of the pump. 
     
     
         6 . The cooling system of  claim 5 , wherein the third thermostat is a three-way thermostat and the cooling system further includes a bypass passage directly connecting the second and third thermostats. 
     
     
         7 . The cooling system of  claim 6 , wherein the second thermostat includes a single movable valve element configured to move between a first end-position at which all of the remaining portion of pressurized coolant from the pump is directed through the engine and all of the pressurized coolant from the aftercooler is directed around the engine, and a second position at which pressurized coolant from the aftercooler and the remaining portion of the pressurized coolant from the pump mix and are directed both through the engine and around the engine. 
     
     
         8 . The cooling system of  claim 7 , wherein the third thermostat includes a valve element movable from a first end-position at which pressurized coolant from the second thermostat is allowed to pass around the engine, toward a second end-position at which pressurized coolant from the second thermostat is inhibited from passing around the engine based on a temperature of pressurized coolant exiting the engine. 
     
     
         9 . The cooling system of  claim 8 , wherein the valve element of the third thermostat is configured to block pressurized coolant directed around the engine only after the valve element of the second thermostat has already moved to the second end-position. 
     
     
         10 . The cooling system of  claim 8 , wherein the valve element of the first thermostat is in the first end-position when a temperature of the pressurized coolant is about 40° C. or higher and in the second end-position when the temperature of the pressurized coolant is about 30° C. or lower. 
     
     
         11 . The cooling system of  claim 8 , wherein the valve element of the second thermostat is in the first end-position when the temperature of the pressurized coolant is about 80° C. or lower and in the second end-position when the temperature of the pressurized coolant is about 90° C. or higher. 
     
     
         12 . The cooling system of  claim 8 , wherein the valve element of the second thermostat is in the first end-position when a temperature of the coolant is about 95° C. or lower and in the second end-position when a temperature of the coolant is about 100° C. or higher. 
     
     
         13 . The cooling system of  claim 2 , wherein at least one of the first thermostat and the second thermostat includes:
 a body at least partially defining a first inlet, a second inlet, a first outlet, and a second outlet; and   a hollow valve element disposed within the body between the first and second inlets and the first and second outlets, the hollow valve element being movable to:
 selectively direct fluid from only the first inlet through the hollow valve element to the first outlet; 
 selectively join fluid received at the first and second inlets; 
 selectively direct a portion of the joined fluid to the first outlet; and 
 selectively direct a remaining portion of the joined fluid to the second outlet. 
   
     
     
         14 . The cooling system of  claim 13 , further including:
 a wax-driven piston member connected to move the hollow valve element; and   a resilient member configured to bias the hollow valve element against the force of the wax-driven piston member toward a position at which fluid from only the first inlet is directed to the first outlet.   
     
     
         15 . The cooling system of  claim 13 , wherein a modulation temperature of the hollow valve element is about 80-90° C. 
     
     
         16 . The cooling system of  claim 1 , wherein the remaining portion is about two to four times the at least a portion during normal operation. 
     
     
         17 . A method of cooling an engine, comprising:
 pressurizing coolant;   always directing at least a portion of the pressurized coolant to absorb heat from air entering the engine;   selectively chilling the at least a portion of the pressurized coolant before the at least a portion of the pressurized coolant absorbs heat from air entering the engine;   selectively mixing the at least a portion of the pressurized coolant with a remaining portion of the pressurized coolant to form a coolant mixture after the at least a portion of the pressurized coolant has absorbed heat from the air; and   selectively directing the coolant mixture through the engine or around the engine based on a temperature of the remaining portion of the pressurized coolant.   
     
     
         18 . The method of  claim 17 , wherein:
 chilling of the at least a portion of the pressurized coolant is at least partially dependent on a temperature of the at least a portion of the pressurized coolant;   the remaining portion of the pressurized coolant is about four times greater than the at least a portion; and   the at least a portion of the pressurized coolant is selectively chilled when the temperature of the at least a portion of the pressurized coolant is greater than about 30° C. prior to absorbing heat from the air.   
     
     
         19 . The method of  claim 17 , wherein:
 when the temperature of the remaining portion of the pressurized coolant is below a temperature range, all of the remaining portion of the pressurized coolant is directed through engine and all of the at least a portion of the pressurized coolant is directed to bypass the engine; and   when the temperature of the remaining portion of the pressurized coolant is within the temperature range, the coolant mixture is directed through the engine.   
     
     
         20 . The method of  claim 19 , wherein:
 pressurized coolant is selectively allowed to bypass and inhibited from bypassing the engine based on a temperature of pressurized coolant exiting the engine;   the temperature range is about 80-90° C.; and   pressurized coolant is inhibited from bypassing the engine when the temperature of the pressurized coolant exiting the engine is less about than 95° C.