Engine cooling system thermostat bypass for dual temperature control

Abstract

A dual temperature control system as part of an engine cooling system. In one aspect, a valve is regulated as a function of engine load and disposed in a by-pass line between the radiator and the coolant pump. The valve is designed to normally block the by-pass line, but permits coolant to by-pass the thermostat and be conveyed from the radiator to the engine when the load of the engine approaches a wide-open-throttle condition. In another aspect, both high-temperature and low-temperature thermostats are employed and a normally closed valve is actuated when the load of the engine approaches a wide-open-throttle condition to permit coolant to be conveyed through the low-temperature thermostat and on to the engine.

What is claimed is:  
     
         1 . An apparatus for regulating a coolant circuit for an engine, the coolant circuit having a radiator, a thermostat, a coolant pump, and a first coolant circuit for coolant flowing through the radiator, thermostat, coolant pump, and engine, the radiator and engine having feed and discharge lines, the apparatus comprising: 
 a second coolant circuit connecting the radiator discharge line to the engine feed line; and    a valve regulated as a function of engine load and disposed in the second coolant circuit, the valve blocking the second coolant circuit under normal operation of the engine and permitting coolant to by-pass the thermostat and be conveyed from the radiator discharge line to the engine feed line when the engine load approaches a wide-open-throttle condition.    
     
     
         2 . The apparatus of  claim 1 , wherein the coolant pump has a feed and discharge line and is located upstream of the engine; and 
 the second coolant circuit is connected from the radiator discharge line to the coolant pump feed line.    
     
     
         3 . The apparatus of  claim 1 , wherein the valve comprises an electronic actuation mechanism.  
     
     
         4 . The apparatus of  claim 1 , wherein the valve comprises a vacuum-actuation mechanism.  
     
     
         5 . The apparatus of  claim 4 , wherein the engine comprises an intake manifold plenum and further comprises a vacuum line, 
 wherein the vacuum line is disposed between the intake manifold plenum and the vacuum-actuation mechanism.    
     
     
         6 . The apparatus of  claim 4 , further comprising a vacuum switching valve, 
 wherein the vacuum switching valve is in fluid communication with the vacuum-actuation mechanism.    
     
     
         7 . An internal combustion engine, the engine having feed and discharge lines, comprising: 
 a radiator for cooling the internal combustion engine, the radiator having feed and discharge lines;    a coolant pump for pumping coolant;    a thermostat for regulating the temperature of the coolant directed to the engine;    a first coolant circuit for the coolant flowing through the radiator, the thermostat, the coolant pump, and the engine;    a second coolant circuit connecting the radiator discharge line to the engine feed line; and    a valve regulated as a function of engine load and disposed in the second coolant circuit, the valve blocking the second coolant circuit under normal operation of the engine and permitting coolant to by-pass the thermostat and be conveyed from the radiator discharge line to the engine feed line when the load of the engine approaches a wide-open-throttle condition.    
     
     
         8 . The engine of  claim 7 , wherein the coolant pump has a feed and discharge line and is located upstream of the engine; and 
 the second coolant circuit is connected from the radiator discharge line to the coolant pump feed line.    
     
     
         9 . A method of regulating the temperature of an engine, comprising: 
 circulating coolant between a radiator and the engine,    regulating the temperature of the engine using a thermostat,    by-passing the thermostat and delivering coolant to the engine when the engine load approaches a wide-open-throttle condition.    
     
     
         10 . The method of  claim 9 , wherein the delivery further comprises conveying coolant from the radiator to a coolant pump that transfers coolant to the engine.  
     
     
         11 . An apparatus for regulating a coolant circuit for an engine, the coolant circuit having a radiator, a first thermostat, a coolant pump, and a first coolant circuit for coolant flowing through the radiator, first thermostat, coolant pump, and engine, the radiator and engine having feed and discharge lines, the apparatus comprising: 
 a second thermostat;    a second coolant circuit connecting the radiator discharge line to the second thermostat to the engine feed line; and    a valve regulated as a function of engine load and disposed in the second coolant circuit, the valve blocking the second coolant circuit under normal operation of the engine and permitting coolant to be conveyed from the radiator discharge line to the second thermostat and to the engine feed line when the load of the engine approaches a wide-open-throttle condition.    
     
     
         12 . The apparatus of  claim 11 , wherein the coolant pump has a feed and discharge line and is located upstream of the engine; and 
 the second coolant circuit is connected from the radiator discharge line to the coolant pump feed line.    
     
     
         13 . An internal combustion engine, the engine having feed and discharge lines, comprising: 
 a radiator for cooling the internal combustion engine, the radiator having feed and discharge lines;    a coolant pump for pumping coolant;    a first thermostat for regulating the temperature of the coolant directed to the engine;    a first coolant circuit for the coolant flowing through the radiator, the first thermostat, the coolant pump, and the engine;    a second thermostat for regulating the temperature of the coolant directed to the engine;    a second coolant circuit connecting the radiator discharge line to the second thermostat to the engine feed line; and    a valve regulated as a function of engine load and disposed in the second coolant circuit, the valve blocking the second coolant circuit under normal operation of the engine and permitting coolant to be conveyed from the radiator discharge line to the second thermostat and to the engine feed line when the load of the engine approaches a wide-open-throttle condition.    
     
     
         14 . The engine of  claim 13 , wherein the coolant pump has a feed and discharge line and is located upstream of the engine; and 
 the second coolant circuit is connected from the radiator discharge line to the coolant pump feed line.    
     
     
         15 . A method of regulating the temperature of an engine, comprising: 
 circulating coolant between a radiator and the engine,    regulating the temperature of the engine using a first thermostat, and    regulating the temperature of the engine using a second thermostat when the load of the engine approaches a wide-open-throttle condition.    
     
     
         16 . The method of  claim 15 , wherein the second thermostat has a setting of less than 190° F.  
     
     
         17 . The method of  claim 15 , wherein the regulating using a second thermostat further comprises delivering lower temperature coolant to the engine.  
     
     
         18 . The method of  claim 15 , wherein the regulating using a second thermostat further comprises conveying coolant to a coolant pump that transfers coolant to the engine.