Method and apparatus for adjusting the pitch of a fan blade

• US 6,592,328 B1
• Filed: 04/17/2001
• Issued: 07/15/2003
• Est. Priority Date: 04/17/2001
• Status: Expired due to Fees

• Current Assignee: Systemair Mfg. Inc.
• Original Assignee: Emerson Electric Company
• Inventors: Cahill, Frank E.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): McCoy, Kimya N
• Application Number:
  US09/836,831
• Time in Patent Office: 819 Days
• Field of Search: 416/36, 416/155, 416/214.R, 440/49, 440/50
• US Class Current: 416/155
• CPC Class Codes: F04D 29/362 during rotation

Abstract

A variable pitch fan blade assembly includes a hub, a pitch-adjusting assembly, a fan blade, and an actuator. The pitch-adjusting assembly includes a first element rotatable on a first axis and a second element rotatable on a second axis. The first element presents an elongated pitch pin. The second element defines an elongated pitch slot receiving the pitch pin. The fan blade is coupled to one of the elements for rotation therewith. The actuator is coupled to the other of the elements for rotation therewith. When the actuator rotates the element to which it is coupled, the element to which the fan blade is coupled is rotated via the pin/slot arrangement, thereby adjusting the pitch of the fan blade.

Claims

1. A pitch adjusting assembly for varying the pitch of a fan blade coupled to a hub, said hub rotatable on a hub axis, said fan blade rotatable relative to the hub on a blade axis, said pitch adjusting assembly comprising:

a first element rotatable on a first element axis and presenting an elongated pin; and

a second element rotatable on a second element axis and defining an elongated slot,

said pin movable about the first element axis and said slot movable about the second element axis,

said element axes being at least substantially perpendicular to one another,

said pin extending at least substantially parallel to one of the axes,

said slot elongated at least substantially parallel to the other of the axes,

said slot receiving the pin at a location offset from both of the axes.

2. A pitch adjusting assembly as claimed in claim 1,

said slot at least partially defined by a pair of opposing substantially parallel edges,

said edges spaced to at least substantially prevent relative edgewise movement of the pin within the slot.

3. A pitch adjusting assembly as claimed in claim 1,

said first and second elements adapted to be disposed within the hub,

said first and second elements adapted to be at least substantially restrained from translation relative to the hub.

4. A pitch adjusting assembly as claimed in claim 1,

one of said elements being couplable to the fan blade for rotation therewith on the blade axis.

5. A pitch adjusting assembly as claimed in claim 4;

and

an actuator coupled to the other of said elements for rotation therewith on an actuator axis.

6. A pitch adjusting assembly as claimed in claim 5,

said actuator coupled to the hub for rotation therewith on the hub axis,

said actuator at least partially rotatable relative to the hub on the actuator axis.

7. A pitch adjusting assembly as claimed in claim 6,

said blade axis and said actuator axis being substantially perpendicular to one another.

8. A pitch adjusting assembly as claimed in claim 7,

one of said element axes having an orientation which at least substantially corresponds to the orientation of the blade axes,

the other of said element axes having an orientation which at least substantially corresponds to the orientation of the actuator axis.

9. A pitch adjusting assembly as claimed in claim 8,

said actuator adapted to be manually rotatable relative to the hub.

10. A pitch adjusting assembly as claimed in claim 9;

and

a resilient spring pawl adapted to be coupled between the hub and one of the elements,

said spring pawl adapted to provide resistance to rotation of said one of the elements relative to the hub.

11. A pitch adjusting assembly as claimed in claim 10,

said one of the elements defining a plurality of pitch notches,

said spring pawl having a shiftable end adapted for receipt in one of said plurality of pitch notches,

said shiftable end being shiftable to an adjacent one of said plurality of pitch notches when a sufficient torsional force is applied to the actuator.

12. A pitch adjusting assembly as claimed in claim 8,

said actuator including a power actuator fixedly couplable to the hub and a rotatable drive shaft fixedly coupled to one of the elements.

13. A pitch adjusting assembly as claimed in claim 12,

said power actuator being a servomotor.

14. A pitch adjusting assembly as claimed in claim 13;

and

a control unit adapted to be located remotely from the hub, said control unit operable to control the rotation of the drive shaft.

15. A variable pitch fan blade assembly comprising:

a rotatable hub;

a pitch-adjusting assembly supported by the hub,

said pitch adjusting assembly including a first element rotatable relative to the hub on a first axis and a second element rotatable relative to the hub on a second axis,

said first element presenting an elongated pitch pin,

said second element defining an elongated pitch slot for receiving the pitch pin so that rotation of one of the elements causes rotation of the other of the elements;

said pin extending at least substantially parallel to one of the axes,

said slot elongated at least substantially parallel to the other of the axes,

a fan blade coupled to one of the elements; and

an actuator coupled to the other of the elements,

said actuator coupled to the hub for rotation therewith,

said actuator at least partially rotatable relative to the hub on one of the first or second axes.

16. A variable pitch fan blade assembly as claimed in claim 15,

said fan blade coupled to the hub for rotation therewith,

said fan blade rotatable relative to the hub on the other of the first or second axes on which the actuator is not rotatable.

17. A variable pitch fan blade assembly as claimed in claim 16,

said first and second axes being substantially perpendicular to one another.

18. A variable pitch fan blade assembly as claimed in claim 17,

said pitch slot and said pitch pin being offset relative to the first and second axes.

19. A variable pitch fan blade assembly as claimed in claim 18,

said pitch slot at least partially defined by a pair of opposing substantially parallel edges,

said edges spaced to at least substantially prevent relative edgewise movement of the pitch pin within the pitch slot.

20. A variable pitch fan blade assembly as claimed in claim 16,

said actuator manually rotatable relative to the hub.

21. A variable pitch fan blade assembly as claimed in claim 20;

and

a plurality of pitch notches on a surface of one of the elements; and

a spring pawl having a first end fixedly coupled to the hub and a second end received in one of said plurality of pitch notches,

said spring pawl providing resistance to rotation of said one of the elements,

said spring pawl shiftable between the plurality of notches by rotating the actuator.

22. A variable pitch fan blade assembly as claimed in claim 16,

said actuator including a motor fixedly coupled to the hub and a rotatable drive shaft fixedly coupled to said other of the elements.

23. A variable pitch fan blade assembly as claimed in claim 22;

and

a control unit located remotely from the variable pitch fan blade assembly,

said control unit operable to control the rotation of the drive shaft.

24. A variable pitch fan blade assembly comprising:

a hub adapted for rotation on a hub axis, said hub having a housing and a pitch wheel disposed within the housing, said housing adapted to rotate on the hub axis, said pitch wheel adapted to rotate relative to the housing on a pitch wheel axis, said pitch wheel presenting an outer radial surface defining a slot; and

a fan blade pivotally coupled to the hub, said fan blade adapted to rotate with the housing around the hub axis, said fan blade further adapted to rotate relative to the housing on a blade axis which is at least substantially perpendicular to the hub axis, said fan blade presenting a protruding pitch pin offset relative to the blade axis, said pitch pin extending at least substantially parallel to the blade axis, said pitch pin received in the slot in the pitch wheel,

said fan blade being rotated on the blade axis when said pitch wheel is rotated relative to the housing, thereby adjusting the pitch of the fan blade.

25. A variable pitch fan blade assembly as claimed in claim 24,

said fan blade having a base and a vane, said base adapted to rotate on the blade axis, said base having a first end coupled to the vane and a second end coupled to the pitch pin,

said housing having a shaft-receiving opening for receiving the base,

said base rotatable within the shaft-receiving opening.

26. A variable pitch fan blade assembly as claimed in claim 24,

said pitch wheel having a plurality of slots for receiving a plurality of the pitch pins presented by a plurality of fan blades, when said pitch wheel is rotated relative to the housing the pitch of the plurality of the fan blades are simultaneously adjusted.

27. A variable pitch fan blade assembly as claimed in claim 24,

said hub axis and said pitch wheel axis having substantially the same orientation.

28. A variable pitch fan blade assembly as claimed in claim 24,

said pitch wheel selectively rotatable on the pitch wheel axis.

29. A variable pitch fan blade assembly as claimed in claim 24,

said pitch wheel manually rotatable relative to the housing.

30. A variable pitch fan blade assembly as claimed in claim 29;

and

a plurality of pitch notches on a surface of the pitch wheel; and

a spring pawl having a first end fixedly coupled to the housing and a second end received in one of said plurality of pitch notches,

said spring pawl providing resistance to rotation of the pitch wheel relative to the housing, said spring pawl sufficiently flexible so that when a sufficient torsional force is applied to the pitch wheel the spring pawl deforms to allow the second end to be shifted out of one of said plurality of pitch notches and into an adjacent one of said plurality of pitch notches, thereby incrementally changing and holding the pitch of the fan blade.

31. A variable pitch fan blade assembly as claimed in claim 24;

and

a power actuator fixedly coupled to the housing, said power actuator having a rotatable drive shaft fixedly coupled to the pitch wheel.

32. A variable pitch fan blade assembly as claimed in claim 31;

and

a control unit located remotely from the variable pitch fan blade assembly, said control unit operable to control the rotation of the drive shaft.

33. A variable pitch fan blade assembly as claimed in claim 32,

said drive shaft, said pitch wheel, and said hub sharing a common axis of rotation.

34. A method of simultaneously varying the pitch of a plurality of fan blades using an actuator, said method comprising the steps of:

(a) coupling a fan blade to a first element rotatable on a first axis;

(b) coupling an actuator to a second element rotatable on a second axis;

(c) inserting an elongated pin presented by one of the elements and extending at least substantially parallel to one of the axes into an elongated slot presented by the other of the elements;

(d) positioning the first and second elements so that the first and second axes are at least substantially perpendicular to one another; and

(e) actuating the actuator to rotate the second element and thereby cause rotation of the blade.

35. A method as claimed in claim 34,

step (e) including manually applying a torsional force to the actuator.

36. A method as claimed in claim 34;

and

(f) coupling a motor of the power actuator to a hub; and

(g) coupling a drive shaft of the power actuator to the second element.

37. A method as claimed in claim 36,

step (e) including rotating the drive shaft.

38. A method as claimed in claim 37;

and

(h) rotating the housing.

39. A method as claimed in claim 38,

step (e) performed simultaneously with step (h).