Flow control valve for engine cooling water

Abstract

A flow control valve comprises a first valve for controlling a radiator flow amount and a second valve for controlling a bypass flow amount. Pressure adjusting passages are respectively provided for the first and second valves for communicating spaces formed at both sides of the respective valves to equalize fluid pressures at both sides, so that a pressure load in an axial direction to the respective valves can be eliminated. As a result, a driving force of an actuator of the flow control valve for directly or indirectly driving the first and second valves can be reduced.

1 . A flow control valve of engine cooling water for a vehicle comprising: 
 a valve housing having a first inlet port to be connected to a radiator, a second inlet port to be connected to a bypass passage and an outlet port to be connected to a water pump, the valve housing further having a first valve passage forming a part of a radiator cooling circuit in which the engine cooling water is circulated from the an engine to the water pump through the radiator, the valve housing further having a second valve passage forming a part of a bypass circuit in which the engine cooling water is circulated from the engine to the water pump through the bypass passage bypassing the radiator;    an actuator for generating a driving force in accordance with an operational condition of the engine;    a first valve movably housed in the valve housing and moved in its axial direction upon operatively receiving the driving force from the actuator, so that an opening degree of the first valve passage is controlled;    a second valve movably housed in the valve housing and moved in its axial direction upon operatively receiving the driving force from the actuator, so that an opening degree of the second valve passage is controlled; and    a pressure adjusting passage for equalizing fluid pressures at both axial sides of at least one of the first and the second valves.    
   
   
       2 . A flow control valve according to  claim 1 , wherein 
 the pressure adjusting passage is formed in the first valve, extending in the axial direction to communicate spaces respectively formed at the both axial sides of the first valve with each other.    
   
   
       3 . A flow control valve according to  claim 1 , wherein 
 the pressure adjusting passage is formed in the second valve, extending in the axial direction to communicate spaces respectively formed at the both axial sides of the second valve with each other.    
   
   
       4 . A flow control valve according to  claim 1 , wherein 
 the actuator has a rotor shaft rotating at an axis which is coaxial with a center axis of the first valve, and    the axial direction of the second valve is almost perpendicular to the axial direction of the rotor shaft.    
   
   
       5 . A flow control valve according to  claim 4 , wherein 
 the first valve has a profile for driving the second valve in its axial direction, so that a desired bypass flow amount with respect to a rotational angle of the rotor shaft is obtained, and    the second valve is biased toward the profile by a biasing means.    
   
   
       6 . A flow control valve according to  claim 1 , wherein 
 the valve housing further comprises:    a mixing chamber for mixing the engine cooling water of a low temperature from the radiator with the engine cooling water of a high temperature bypassing the radiator;    a radiator side passage for flowing the engine cooling water from the radiator into the mixing chamber;    a bypass side passage for flowing the engine cooling water from the bypass passage into the mixing chamber; and    a pump side passage for flowing out the engine cooling water from the mixing chamber to the water pump.    
   
   
       7 . A flow control valve according to  claim 1 , wherein 
 the valve housing has further a third valve passage forming a part of a heater circuit in which the engine cooling water is circulated from the engine to the water pump through a heater.    
   
   
       8 . A flow control valve according to  claim 7 , further comprising: 
 a third valve movably housed in the valve housing and moved in its axial direction upon operatively receiving the driving force from the actuator, so that an opening degree of the third valve passage is controlled; and    another pressure adjusting passage for equalizing fluid pressures at both axial sides of the valve.    
   
   
       9 . A flow control valve according to  claim 8 , wherein 
 the other pressure adjusting passage is formed in the third valve, extending in the axial direction to communicate spaces respectively formed at the both axial sides of the third valve with each other.    
   
   
       10 . A flow control valve according to  claim 8 , wherein 
 the actuator has a rotor shaft rotating at an axis which is coaxial with a center axis of the first valve, and    the axial direction of the third valve is almost perpendicular to the axial direction of the rotor shaft.    
   
   
       11 . A flow control valve according to  claim 10 , wherein 
 the first valve has a profile for driving the third valve in its axial direction, so that a desired heater flow amount with respect to a rotational angle of the rotor shaft is obtained, and    the third valve is biased toward the profile by a biasing means.    
   
   
       12 . A flow control valve according to  claim 7 , wherein 
 the valve housing further comprises:    a mixing chamber for mixing the low temperature engine cooling water radiated at the heater, the engine cooling water of a low temperature from the radiator and the engine cooling water of a high temperature bypassing the radiator with one another;    a heater side passage for flowing the engine cooling water from the heater into the mixing chamber;    a radiator side passage for flowing the engine cooling water from the radiator into the mixing chamber;    a bypass side passage for flowing the engine cooling water from the bypass passage into the mixing chamber; and    a pump side passage for flowing out the engine cooling water from the mixing chamber to the water pump.