Thermostat for engine cooling system

Abstract

A thermostat for an engine cooling system, which is arranged between an engine and a radiator may include a housing having a coolant inlet through which coolant flows in from the engine and an outlet leading the coolant to the radiator; and a main valve provided in the housing and coupled to one side of wax to open or close the outlet as the volume of the wax is changed. In particular, the main valve is formed with a coolant hole.

What is claimed is: 
     
         1 . A thermostat for an engine cooling system, which is arranged between an engine and a radiator, comprising:
 a housing having a coolant inlet through which coolant flows in from the engine and an outlet leading the coolant to the radiator; and   a main valve provided in the housing and coupled to one side of wax and configured to open or close the outlet as a volume of the wax is changed,   wherein the main valve is formed with at least one coolant hole.   
     
     
         2 . The thermostat according to  claim 1 , further comprising a bracket provided in the housing and configured to support the main valve,
 wherein the bracket comprises an upper plate configured to contact or be separated from the main valve so as to open or close the outlet leading, and a stepped portion formed in an inner diameter portion of the upper plate is arranged so as to abut against a part of the main valve.   
     
     
         3 . The thermostat according to  claim 2 , wherein the at least one coolant hole of the main valve is arranged at a position to be abutted against the stepped portion. 
     
     
         4 . The thermostat according to  claim 2 , wherein the at least one coolant hole is opened before the main valve opens the outlet leading to the radiator such that some of the coolant flows through the at least one coolant hole to the outlet leading to the radiator. 
     
     
         5 . The thermostat according to  claim 2 , wherein the at least one coolant hole comprises a plurality of coolant holes formed through top and bottom surfaces of the main valve, and the plurality of coolant holes are arranged along a peripheral portion of the main valve with predetermined intervals. 
     
     
         6 . The thermostat according to  claim 2 , further comprising: a bypass valve configured to open or close a bypass outlet formed in the housing, the bypass outlet configured to guide the coolant coming through the coolant inlet to the engine. 
     
     
         7 . The thermostat according to  claim 6 , wherein the bypass valve is configured to move in a direction of closing the bypass outlet when the at least one coolant hole is moved in a direction of being opened. 
     
     
         8 . The thermostat according to  claim 6 , wherein the bypass valve is configured to be connected to the wax by a shaft of the bypass valve to operate with the main valve. 
     
     
         9 . The thermostat according to  claim 2 , wherein a flow path to the radiator is closed when the main valve is in contact with both the upper plate and the stepped portion; the flow path to the radiator is opened partially when the main valve is in contact with the upper plate and spaced apart from the stepped portion; and the flow path to the radiator is opened when the main valve is spaced apart from both the upper plate and the stepped portion.