Blade system for fans for industrial use

1. A blade system for fans for industrial use, comprising:

a blade, which extends longitudinally along a first reference axis and defines within it a cavity, wherein said blade has a cross section with a flattened profile and is oriented with a major dimension along a second reference axis;

a supporting unit, on which said blade is fixed and which is inserted within the cavity of said blade, said cavity of said blade having a cylindrical conformation and a cross section with flattened profile and is oriented with the major dimension along said second reference axis;

said supporting unit comprising a tubular bar, which has a cross section with a flattened profile and is oriented with the major dimension along said second reference axis, or a first tubular bar and a second tubular bar with circular cross sections, which are arranged alongside one another along said second reference axis;

a positioning member located at an end of said supporting unit, wherein said positioning member is configured to connect the supporting unit and blade to a rotor of a fan;

a connection device including a seat configured to receive the positioning member; and

wherein said positioning member is rotatable about the first reference axis such that the orientation of the blade can vary when said positioning member is coupled to said seat.

2. The system according to claim 1 , wherein the cross section of said tubular bar has a profile comprising two circular portions joined together by two opposed intermediate portions.

3. The system according to claim 2 , wherein said two circular portions each reproduce an arc of a circle defined by an angle greater than 180°.

4. The system according to claim 3 , wherein said two circular portions have the same size or a difference between their areas of less than 15%.

5. The system according to claim 1 , wherein said first and second tubular bars have the same size or a difference between their areas of less than 15%.

6. The system according to claim 1 , wherein the cross section of said tubular bar has a flattened profile selected from one of the following: rectangular, elliptical, trapezial, and rhomboidal.

7. The system according to claim 1 , wherein said first and second bars are arranged in contact with one another, or at a distance apart that is negligible with respect to their longitudinal dimension.

8. The system according to claim 1 , wherein said first and second bars are joined together via connection members.

9. The system according to claim 1 , comprising at least one adapter, which is prearranged for receiving said tubular bar or said first and second tubular bars, and for setting itself within said cavity between the walls of said cavity and said tubular bar or said first and second tubular bars.

10. The system according to claim 1 , wherein the positioning member is coupled to the seat with a rotary-type coupling, providing the possibility of varying the orientation of the blade about said first reference axis.

11. The system according to claim 10 , wherein said positioning member comprises two opposed shaped elements, which are prearranged for gripping between them said tubular bar or said first and second bars and define, as a whole, an outer cylindrical surface.

12. The system according to claim 11 , wherein said two opposed elements are prearranged for defining an internal passage, which is traversed by said bar, or by said first and second bars, and is delimited by walls that follow the external profile of said bar or of said first and second bars.

13. The system according to claim 2 , wherein said two circular portions have the same size or a difference between their areas of less than 15%.

14. The system according to claim 6 , wherein said first and second bars are arranged in contact with one another, or at a distance apart that is negligible with respect to their longitudinal dimension.

15. The system according to claim 5 , wherein said first and second bars are joined together via connection members.

16. The system according to claim 6 , wherein said first and second bars are joined together via connection members.

17. The system according to claim 7 , wherein said first and second bars are joined together via connection members.

18. The system according to claim 8 , comprising at least one adapter, which is prearranged for receiving said tubular bar or said first and second tubular bars, and for setting itself within said cavity between the walls of said cavity and said tubular bar or said first and second tubular bars.

19. The system according to claim 9 , wherein said positioning member is coupled to the seat with a rotary-type coupling, providing the possibility of varying the orientation of the blade about said first reference axis.

20. The system according to claim 19 , wherein said positioning member comprises two opposed shaped elements, which are prearranged for gripping between them said tubular bar or said first and second bars and define, as a whole, an outer cylindrical surface.

21. The system according to claim 1 , wherein the seat includes a shape and size corresponding to said positioning member.

22. The system according to claim 1 , wherein said connection device is coupled to the rotor of a fan.

23. The system according to claim 11 , wherein said seat includes a cylindrical shape corresponding to the outer cylindrical surface of the positioning member.

24. The system according to claim 23 , wherein said connection device includes a first piece and a second piece, wherein the first piece and the second piece define the seat when the first piece and the second piece are connected to one another.

25. The system according to claim 20 , wherein said seat includes a cylindrical shape corresponding to the outer cylindrical surface of the positioning member.

26. The system according to claim 25 , wherein said connection device includes a first piece and a second piece, wherein the first piece and the second piece define the seat when the first piece and the second piece are connected to one another.