SPIN VANE CONTROL FOR FANS
United States Patent 3583827
A fan having an air moving rotor with an inlet sheet extending around the shaft and with an annular spin vane support around the shaft is provided with a plurality of spin inducing vanes pivoted at said sheet and support with at least one spoiler tab means projecting from the downstream surface of an associated van to remove the spin from the air in a small annulus around and close to the surface of the shaft. Each spoiler tab projects from the downstream surface of the vane at a position near the lower end of the pivot axis of the vane at an angle to approximately align with the rotor shaft when the vane is pivoted at or less than its mid position towards its closed position.
US Patent References:
Spin vane controls for fans
McDonald - May 1958 - 2834536
Secondary flow reducer
Lee - January 1960 - 2920864
Spin vane controls for fans
McDonald - May 1958 - 2834536
Secondary flow reducer
Lee - January 1960 - 2920864
Application Number:
04/875130
Publication Date:
06/08/1971
Filing Date:
11/10/1969
View Patent Images:
Export Citation:
Assignee:
Westinghouse Electric Corporation (Pittsburgh, PA)
Primary Class:
Other Classes:
415/160
International Classes:
F04D29/46; F04D27/00; F04D29/46
Field of Search:
415/159--164 416/236
Primary Examiner:
Croyle, Carlton R.
Assistant Examiner:
Vrablik, John J.
Claims:
I claim as my invention
1. A fan having a fan shaft with an air moving rotor, an inlet sheet extending around said shaft, an annular spin vane support around said shaft, a plurality of spin inducing vanes pivoted at said sheet and said support, at least one of said vanes having spoiler tab means for removing the spin from the air in a small annulus around and close to the surface of the shaft, each of said tab means protruding from the downstream face of the associated vane near the lower end of the pivot axis of the vane at an angle to approximately align with said shaft when said vane is pivoted at or less than its mid position towards its closed position at which in the absence of said tab, undesired fan pulsations would ordinarily occur.
2. The invention of claim 1 in which said tab protrudes from said vane at an angle within the range of 45° to 70° from the plane of the vane.
1. A fan having a fan shaft with an air moving rotor, an inlet sheet extending around said shaft, an annular spin vane support around said shaft, a plurality of spin inducing vanes pivoted at said sheet and said support, at least one of said vanes having spoiler tab means for removing the spin from the air in a small annulus around and close to the surface of the shaft, each of said tab means protruding from the downstream face of the associated vane near the lower end of the pivot axis of the vane at an angle to approximately align with said shaft when said vane is pivoted at or less than its mid position towards its closed position at which in the absence of said tab, undesired fan pulsations would ordinarily occur.
2. The invention of claim 1 in which said tab protrudes from said vane at an angle within the range of 45° to 70° from the plane of the vane.
Description:
CROSS REFERENCES TO RELATED PATENT APPLICATIONS
So far as is known, this invention is not related to any pending patent applications.
BACKGROUND OF THE INVENTION
Inlet spin vanes for controlling the capacity of a fan or blower are well known and there are problems of fan pulsations that occur when the vanes are at or less than their mid positions towards their closed positions for reducing the fan capacity. U.S. Pat. No. 2,834,536, issued on May 13, 1958, discloses the provision of a spoilertab projecting from one edge of the van towards the rotor shaft at an angle to approximately align with the shaft when the vane is at or near its mid position to remove the spin from the air in a small annulus near the surface of the shaft for the purpose of eliminating the objectionable fan pulsations. In this prior art arrangement there are some disadvantages, since the spoiler tab is located to extend from an edge of the tab which is, relatively speaking at a considerable distance from the pivot axis of the vane, thereby setting up an undesirable torque reaction on the van, and its pivot control members. Also, as may not be immediately obvious, the position of the spoiler tab as provided by the prior art arrangement to extend from a side edge of the van is actually considerably removed from the surface of the shaft and in fact moves further away from the shaft as the vane is pivoted from its mid position towards its closed position.
PRIOR ART
U.S. Pat. No. 2,834,536 represents the most pertinent prior art with which applicant is presently familiar.
SUMMARY
In order to reduce the torque reaction on the vane and to provide a more effective spin removing of the air in an annulus closest to the rotor shaft, this invention provides for the attachment of a spin removing spoiler tab to project from the downstream surface of the spin vane from a position near the lower pivot axis of the vane so that the reaction torque arm length of the tab on the vane is near a minimum and so that the tab will be close to the surface of the rotor shaft for all effective spin removing positions of the vane and tab.
Further objects, features and the attendant advantages of the invention will be apparent with reference to the following specification and drawing .
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary sectional view of a fan showing the positions of the spin vanes having the spoiler tab arrangement of the invention.
FIG. 2 is a plane view of one of the spin vane and spoiler tab arrangements of the invention; and
FIG. 3 is an end view from the top end of the vane showing the relative angular positions of the vane and tab for one embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
Referring to FIG. 1 of the drawing, a fan is shown at 10 to be secured to the fan rotor shaft 11. An inlet sheet 12 extends around the rotor shaft 11 and an annular spin vane support 13 is also positioned around the rotor shaft 11. Pivotally positioned on pivot axes such as shown at 14 and 15 are a plurality of spin vanes such as shown at 16 and 17. It will be seen that each vane pivot axis or shaft such as the pivot shafts 14 and 15 extend from the annular support 13 to the inlet sheet 12 and suitable control arms such as the lever arms shown at 18 and 19 are provided to rotate their respective pivot shafts 14 and 15 and spin vanes 16 and 17 for purposes of controlling the capacity of the fan as is well known in the art. Since the details of the control levers 18 and 19 are not a part of the present invention they have not been shown and only the levers 18 and 19 are shown in a general relation.
In order to remove the spin from the air in a small annulus close to the surface of the rotor shaft 11 when the vanes 16 and 17 are in their mid position or less than their mid position towards their closed position, one or more of the spin vanes 16, 17 is provided with an associated spin removing tab such as the tab 20 for van 14 or the tab 21 for vane 17. It should be understood that the fully closed position of any of the vanes such as vanes 16 and 17 for reducing the capacity of the fan to a minimum is a position wherein the vanes effectively close the inlet air flow with the planes of the vanes extending generally across the direction of the air flow. As shown by FIGS. 2 and 3 of the drawing each spoiler spin removing tab such as the tab 20 for vane 16 projects from the downstream surface 22 of the vane 16 at an angle which will put the plane of the tab in general alignment with the axis of the shaft 11 when the spin vane is at or less than its mid position towards its closed position. In other words each spoiler tab such as the spoiler tab 20 should extend in the direction of the air flow from the downstream surface of the vane at an angle between 45 to 70° from the plane of the vane. As shown by FIG. 3 of the drawings one preferred embodiment of the invention would position the spoiler tab 20 to project from the downstream surface of the vane 16 at an angle of 60° so as to be in alignment with the shaft axis 11 when the vane is positioned at an angle of 30° from the fully closed position at right angles to the direction of the air flow or the shaft axis 11.
It will be noted that the position of the spoiler tab 20 as shown by FIG. 2 of the drawings is preferably on the downstream side of and very close to the pivot axis 14 at the lower end of the vane 16 adjacent the vane support hub 13 in the assembled relation. Thus the effective length of the torque arm of the tab 20 relative to the pivot axis 14 of the vane 16 is at a minimum. Also with the spoiler tab 20 located as shown by FIG. 2 of the drawing, the tab 20 remains relatively close to the surface of the shaft 11 during rotational movement of the vane 16 from the closed position to about its mid position of 45° relative to the axis of the shaft 11 and the air flow.
Various modifications will occur to those skilled in the art.
So far as is known, this invention is not related to any pending patent applications.
BACKGROUND OF THE INVENTION
Inlet spin vanes for controlling the capacity of a fan or blower are well known and there are problems of fan pulsations that occur when the vanes are at or less than their mid positions towards their closed positions for reducing the fan capacity. U.S. Pat. No. 2,834,536, issued on May 13, 1958, discloses the provision of a spoilertab projecting from one edge of the van towards the rotor shaft at an angle to approximately align with the shaft when the vane is at or near its mid position to remove the spin from the air in a small annulus near the surface of the shaft for the purpose of eliminating the objectionable fan pulsations. In this prior art arrangement there are some disadvantages, since the spoiler tab is located to extend from an edge of the tab which is, relatively speaking at a considerable distance from the pivot axis of the vane, thereby setting up an undesirable torque reaction on the van, and its pivot control members. Also, as may not be immediately obvious, the position of the spoiler tab as provided by the prior art arrangement to extend from a side edge of the van is actually considerably removed from the surface of the shaft and in fact moves further away from the shaft as the vane is pivoted from its mid position towards its closed position.
PRIOR ART
U.S. Pat. No. 2,834,536 represents the most pertinent prior art with which applicant is presently familiar.
SUMMARY
In order to reduce the torque reaction on the vane and to provide a more effective spin removing of the air in an annulus closest to the rotor shaft, this invention provides for the attachment of a spin removing spoiler tab to project from the downstream surface of the spin vane from a position near the lower pivot axis of the vane so that the reaction torque arm length of the tab on the vane is near a minimum and so that the tab will be close to the surface of the rotor shaft for all effective spin removing positions of the vane and tab.
Further objects, features and the attendant advantages of the invention will be apparent with reference to the following specification and drawing .
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary sectional view of a fan showing the positions of the spin vanes having the spoiler tab arrangement of the invention.
FIG. 2 is a plane view of one of the spin vane and spoiler tab arrangements of the invention; and
FIG. 3 is an end view from the top end of the vane showing the relative angular positions of the vane and tab for one embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
Referring to FIG. 1 of the drawing, a fan is shown at 10 to be secured to the fan rotor shaft 11. An inlet sheet 12 extends around the rotor shaft 11 and an annular spin vane support 13 is also positioned around the rotor shaft 11. Pivotally positioned on pivot axes such as shown at 14 and 15 are a plurality of spin vanes such as shown at 16 and 17. It will be seen that each vane pivot axis or shaft such as the pivot shafts 14 and 15 extend from the annular support 13 to the inlet sheet 12 and suitable control arms such as the lever arms shown at 18 and 19 are provided to rotate their respective pivot shafts 14 and 15 and spin vanes 16 and 17 for purposes of controlling the capacity of the fan as is well known in the art. Since the details of the control levers 18 and 19 are not a part of the present invention they have not been shown and only the levers 18 and 19 are shown in a general relation.
In order to remove the spin from the air in a small annulus close to the surface of the rotor shaft 11 when the vanes 16 and 17 are in their mid position or less than their mid position towards their closed position, one or more of the spin vanes 16, 17 is provided with an associated spin removing tab such as the tab 20 for van 14 or the tab 21 for vane 17. It should be understood that the fully closed position of any of the vanes such as vanes 16 and 17 for reducing the capacity of the fan to a minimum is a position wherein the vanes effectively close the inlet air flow with the planes of the vanes extending generally across the direction of the air flow. As shown by FIGS. 2 and 3 of the drawing each spoiler spin removing tab such as the tab 20 for vane 16 projects from the downstream surface 22 of the vane 16 at an angle which will put the plane of the tab in general alignment with the axis of the shaft 11 when the spin vane is at or less than its mid position towards its closed position. In other words each spoiler tab such as the spoiler tab 20 should extend in the direction of the air flow from the downstream surface of the vane at an angle between 45 to 70° from the plane of the vane. As shown by FIG. 3 of the drawings one preferred embodiment of the invention would position the spoiler tab 20 to project from the downstream surface of the vane 16 at an angle of 60° so as to be in alignment with the shaft axis 11 when the vane is positioned at an angle of 30° from the fully closed position at right angles to the direction of the air flow or the shaft axis 11.
It will be noted that the position of the spoiler tab 20 as shown by FIG. 2 of the drawings is preferably on the downstream side of and very close to the pivot axis 14 at the lower end of the vane 16 adjacent the vane support hub 13 in the assembled relation. Thus the effective length of the torque arm of the tab 20 relative to the pivot axis 14 of the vane 16 is at a minimum. Also with the spoiler tab 20 located as shown by FIG. 2 of the drawing, the tab 20 remains relatively close to the surface of the shaft 11 during rotational movement of the vane 16 from the closed position to about its mid position of 45° relative to the axis of the shaft 11 and the air flow.
Various modifications will occur to those skilled in the art.