Inline thermostat control systems and methods

Abstract

A snowmobile coolant system that includes an engine outlet line, an engine inlet line, and an inlet thermostat. The engine outlet line provides coolant flow between an engine and a heat exchanger of the snowmobile. The engine inlet line provides coolant flow between the heat exchanger and the engine. The inlet thermostat is positioned in the engine inlet line and is operable between open and closed states based on a temperature of coolant flowing from the heat exchanger to the inlet thermostat.

What is claimed is: 
     
         1 . A snowmobile coolant system, comprising:
 an engine outlet line providing coolant flow between an engine and a heat exchanger of the snowmobile;   an engine inlet line providing coolant flow between the heat exchanger and the engine;   an inlet thermostat positioned in the engine inlet line and operable between open and closed states based on a temperature of coolant flowing from the heat exchanger to the inlet thermostat.   
     
     
         2 . The snowmobile coolant system of  claim 1 , further comprising an outlet thermostat positioned in the engine outlet line and operable between open and closed states based on a temperature of coolant flowing from the engine to the outlet thermostat. 
     
     
         3 . The snowmobile coolant system of  claim 2 , further comprising a bypass line providing coolant flow between an outlet of the engine and the engine inlet line. 
     
     
         4 . The snowmobile coolant system of  claim 3 , wherein the bypass line provides constant flow between the engine outlet and the engine inlet line when the engine is running. 
     
     
         5 . The snowmobile coolant system of  claim 1 , wherein the inlet thermostat includes at least one bleeder hole that provides coolant flow through the thermostat when the thermostat is in the closed state. 
     
     
         6 . The snowmobile coolant system of  claim 1 , wherein the inlet thermostat opens and closes at a temperature in the range of about 120° F. and 160° F. 
     
     
         7 . The snowmobile coolant system of  claim 1 , further comprising an inlet thermostat housing configured to house the inlet thermostat, the inlet thermostat housing having a housing outlet, a housing inlet and a side inlet, the side inlet having a smaller cross-sectional size than a cross-sectional size of the housing inlet. 
     
     
         8 . The snowmobile coolant system of  claim 7 , wherein the inlet thermostat housing comprises two pieces configured to connect together. 
     
     
         9 . The snowmobile coolant system of  claim 7 , further comprising a bypass line extending from the side inlet to an outlet of the engine. 
     
     
         10 . The snowmobile coolant system of  claim 7 , wherein the inlet thermostat housing comprises first and second housing pieces, which when assembled together capture the inlet thermostat within the inlet thermostat housing. 
     
     
         11 . A vehicle dual zone coolant system, comprising:
 a first thermostat positioned in an outlet coolant line coupled in flow communication between a coolant outlet of an engine and an heat exchanger of the vehicle;   a second thermostat positioned in an inlet coolant line coupled in flow communication between the heat exchanger and a coolant inlet of the engine;   a bypass line extending from the engine upstream of the first thermostat to the inlet coolant line downstream of the second thermostat;   wherein the first and second thermostats control coolant flow to and from the engine.   
     
     
         12 . The vehicle dual zone coolant system of  claim 11 , wherein the heat exchanger includes a radiator. 
     
     
         13 . The vehicle dual zone coolant system of  claim 11 , wherein the vehicle is a snowmobile and the heat exchanger is exposed in a drive track tunnel of the snowmobile. 
     
     
         14 . The vehicle dual zone coolant system of  claim 11 , wherein the first and second thermostats are operable to open and close at a temperature within a range of about 100° F. to about 160° F. 
     
     
         15 . The vehicle dual zone coolant system of  claim 11 , wherein the second thermostat is carried by a two-part inlet thermostat housing. 
     
     
         16 . The vehicle dual zone coolant system of  claim 15 , wherein the two-part inlet thermostat housing includes an engine outlet, a heat exchanger inlet and a side inlet, the side inlet being connected in flow communication with the bypass line. 
     
     
         17 . A method of controlling coolant temperatures in a snowmobile, the method comprising:
 providing an inlet thermostat, an engine inlet coolant line, an engine outlet coolant line, and a bypass line;   connecting the engine inlet coolant line to a heat exchanger outlet and an engine coolant inlet;   connecting the engine outlet coolant line to a heat exchanger inlet and an engine coolant outlet;   positioning the inlet thermostat in the engine inlet coolant line;   coupling the bypass line to the engine coolant outlet and the engine inlet coolant line downstream of the thermostat;   operating the inlet thermostat to control a temperature of coolant entering the engine.   
     
     
         18 . The method of  claim 17 , further comprising providing an outlet thermostat and positioning the outlet thermostat in the engine outlet coolant line. 
     
     
         19 . The method of  claim 17 , wherein the inlet thermostat includes at least one bleeder hole configured to provide flow through the inlet thermostat when the inlet thermostat is in a closed state. 
     
     
         20 . The method of  claim 18 , wherein operating the inlet thermostat includes opening and closing the inlet thermostat based on a temperature of coolant received from the heat exchanger.