Variable-geometry fan and method for control thereof

Abstract

A variable-geometry fan, for cooling the lubricant of an internal-combustion engine includes a hub bearing a ring of blades having an elastically deformable structure and incorporating laminas made of a shape-memory alloy. The application of thermal energy to the laminas, so as to vary the geometry of the blades, envisages circulation of a hot fluid and of a cold fluid through internal ducts of the blades.

What is claimed is: 
     
         1 . A variable-geometry fan for cooling a lubricant of an internal-combustion engine, comprising:
 a rotating hub bearing a ring of blades each having elastically deformable structure incorporating at least one lamina made of a shape-memory alloy, and   control means for applying thermal energy to said at least one lamina so as to vary the geometry of the blade, wherein said control means include a circuit for circulation of a thermal fluid through internal ducts of each blade.   
     
     
         2 . The fan according to  claim 1 , wherein said circuit for circulation of a thermal fluid includes a first delivery line and a first return line for a hot liquid, a second delivery line and a second return line for a cold liquid, solenoid-valve means for opening and closing the communication between said ducts and said first lines or said second lines, and an electronic control unit operatively connected to said solenoid-valve means. 
     
     
         3 . The fan according to  claim 2 , wherein said electronic control unit is configured for driving opening and closing of said solenoid-valve means as a function of the temperature of the engine lubricant. 
     
     
         4 . The fan according to  claim 3 , wherein said electronic control unit is configured for operating according to selectively modifiable logics. 
     
     
         5 . The fan according to  claim 1 , wherein said at least one shape-memory lamina is set along said internal ducts of the blade. 
     
     
         6 . The fan according to  claim 5 , wherein said at least one shape-memory lamina is exposed in said internal duct on both of its faces. 
     
     
         7 . The fan according to  claim 1 , wherein the hub has a radial distributor communicating with the internal ducts of the blades and connected to an inlet duct and to an outlet duct of said thermal fluid set coaxially with respect to the hub. 
     
     
         8 . The fan according to  claim 7 , wherein said inlet and outlet ducts include respective rotatable sections turning with said hub and connected to respective stationary sections via sliding-seal connectors. 
     
     
         9 . The fan according to  claim 8 , wherein said sliding-seal connectors include annular sliding bearings. 
     
     
         10 . The fan according to  claim 1 , wherein each blade is formed by a pair of half-shells seal-fitted together and having respective channels facing one another to form said ducts. 
     
     
         11 . The fan according to  claim 1 , wherein said thermal fluid comprises coolant of the internal-combustion engine. 
     
     
         12 . A method for controlling the geometry of the blades of a variable-geometry fan for cooling a lubricant of an internal-combustion engine, in which said blades have an elastically deformable structure incorporating laminas made of a shape-memory alloy to which thermal energy is applied, wherein application of the thermal energy comprises circulating a thermal fluid through internal ducts of each blade, to which ducts said laminas are exposed. 
     
     
         13 . The method according to  claim 12 , wherein the thermal fluid includes a hot liquid and a cold liquid, and further comprising controlling circulation of the fluid through said internal ducts as a function of the temperature of the lubricant of the engine to which the fan is applied. 
     
     
         14 . The method according to  claim 12 , wherein said thermal fluid comprises a coolant of the internal-combustion engine to which the fan is applied.