Patent ID: 6837193

Claim:
A flow control valve which is used in a cooling system of a water cooling type for cooling an engine by circulating cooling water by a water pump and radiating heat of the cooling water by a radiator; the cooling system including a cooling water passage provided in the engine, a radiator flow passage for permitting the cooling water flowing out of the cooling water passage to return to the water pump through the radiator, a bypass flow passage for permitting the cooling water flowing out of the cooling water passage to directly return to the water pump without passing through the radiator, and an electronic control device for controlling the flow control valve, the radiator flow passage and the bypass flow passage being connected to the flow control valve at a position upstream from the water pump; the flow control valve including a first valve body and a first valve seat for controlling a radiator flow quantity corresponding to a flow quantity of the cooling water flowing in the radiator passage, a second valve body and a second valve seat for controlling a bypass flow quantity corresponding to a flow quantity of the cooling water flowing in the bypass passage, and an actuator for displacing the first and second valve bodies integrally as one valve; the electronic control device for controlling the actuator to displace the valve, thereby regulating the radiator flow quantity and the bypass flow quantity to control a temperature of the cooling water to a target temperature; the radiator flow quantity and the bypass flow quantity are defined in terms of ranges in relation to the displacement amount of the valve so that each structure of the first valve body and the first valve seat and each structure of the second valve body and the second valve seat are determined to have a flow quantity characteristic that the bypass flow quantity is slightly larger than the radiator flow quantity in a range where the radiator flow quantity becomes practically zero and, in other ranges, the bypass flow quantity is equal to or lower than the radiator flow quantity.