Patent ID: 7172135
Filing Date: 2007-02-06
Classification: F01P,F16K,G05D

Abstract:
1. A thermostat for a dual-circuit cooling system used in a cooling system comprising cooling water circulating passages of two independent circuits of an automobile engine, and a thermally expandable body which thermally expands and shrinks following changes in the temperature of cooling water and which opens and closes a valve body by a piston which is moved back and forth by volume changes of said thermally expandable body, said thermostat comprising: a first valve body having a first passage, a second passage which is constantly communicated with the first passage, and a third passage that is selectively connected to said first and second passages, said first valve body being configured to maintain a closed valve state so as to disconnect the communication of the third passage when the temperature of cooling water is not higher than a prescribed temperature and configured to open when the temperature of cooling water exceeds said prescribed temperature; a second valve body having a fourth passage and a fifth passage that is selectively communicated with the fourth passage, said second valve being configured to close so as to disconnect said fourth and fifth passages in response to the operation of the first valve body when the temperature of cooling water is not higher than the prescribed temperature, and configured to open in response to the operation of the first valve body when the temperature of cooling water is equal to or higher than the prescribed temperature; and a partitioning member sealing a first control chamber comprising said first valve body and a second control chamber comprising said second valve body such that said first control chamber and said second control chamber are not communicated with each other, wherein said partitioning member comprises a tubular sleeve incorporating the second valve body inside thereof.