Shrouded fan impeller with reduced cover overlap

Patent metadata

Field	Value
Publication number	US-9765788-B2
Application number	US-201414559672-A
Country	US
Kind code	B2
Filing date	Dec 3, 2014
Priority date	Dec 4, 2013
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

The described embodiments relate to improving efficiency of a low-profile cooling fan. In one embodiment, an impeller of the cooling fan includes a shroud which covers a central portion of the impeller, thereby allowing a central inlet portion of the blades to have an increased fan blade height when compared to a cooling fan constrained by minimum part tolerances between the fan blades and a portion of the fan housing. In some embodiments, the impeller includes splitter blades that can improve performance of the low-profile cooling fan.

First claim

What is claimed is:

1. An impeller enclosed within a cover, the impeller comprising:
a central hub;
a plurality of blades extending radially from the central hub; and
a ring shaped shroud attached to the plurality of blades separated from the cover by a radial gap configured to allow the ring shaped shroud to rotate with the plurality of blades without contacting the cover, wherein the ring shaped shroud is characterized by an outermost radial edge and an inner edge, wherein the ring shaped shroud is characterized by a first thickness at the inner edge and a second thickness at the outermost radial edge, and wherein the second thickness is greater than the first thickness.

2. The impeller of claim 1 , wherein the ring shaped shroud increases in thickness along a gradient from an innermost edge to the outermost radial edge.

3. The impeller of claim 1 , wherein the plurality of blades is integrally formed with the ring shaped shroud.

4. The impeller of claim 1 , wherein the ring shaped shroud has a first side and an opposing second side, wherein the plurality of blades is positioned on the first side of the ring shaped shroud.

5. The impeller of claim 4 , wherein each of the plurality of blades has a trailing edge and a leading edge, wherein the ring shaped shroud is positioned at a central portion between the leading edge and the trailing edge of each of the plurality of blades.

6. The impeller of claim 4 , wherein the plurality of blades has trailing edges and leading edges, and wherein the ring shaped shroud has an outer edge defining an outer diameter and an inner edge defining an inner diameter, wherein the plurality of blades is circularly arranged such that the leading edges define a leading edge diameter and the trailing edges define a trailing edge diameter, wherein the plurality of blades are arranged with respect to the ring shaped shroud such that the trailing edge diameter is larger than the outer diameter of the ring shaped shroud.

7. The impeller of claim 6 , wherein the leading edge diameter of the plurality of blades is smaller than the inner diameter of the ring shaped shroud.

8. The impeller of claim 1 , wherein each of the plurality of blades has a curved geometry.

9. The impeller of claim 1 , wherein the impeller includes a plurality of splitter blades, each of the plurality of splitter blades positioned between pairs of the plurality of blades, wherein a length of each of the plurality of splitter blades is less than a length of each of the plurality of blades.

10. The impeller of claim 9 , wherein each of the plurality of splitter blades has a common length.

11. The impeller of claim 9 , wherein the plurality of splitter blades is characterized as having at least two different lengths.

12. A fan assembly, comprising:
a housing;
a cover that cooperates with the housing to define a fan assembly interior portion, the cover defining a fan inlet zone external to the fan assembly suitable for receiving an air flow in accordance with a pressure difference; and
an impeller arranged to rotate in a manner that creates the pressure difference to drive the air flow and disposed within the interior portion of the fan assembly, the impeller comprising a plurality of fan blades that are integrally formed with a shroud that extends toward leading edges of the plurality of fan blades, the shroud and cover defining a radial gap, wherein the shroud is characterized by an annular shape having an outermost radial edge and an inner edge, wherein the shroud is further characterized by a first thickness at the inner edge and a second thickness at the outermost radial edge, and wherein the second thickness is greater than the first thickness.

13. The fan assembly as recited in claim 12 , wherein a surface of the shroud is configured to bias air flow away from the radial gap between the shroud and the cover.

14. The fan assembly as recited in claim 12 , wherein an outer diameter of the shroud extends to an outer tip of each of the plurality of fan blades.

15. The fan assembly as recited in claim 12 , wherein the plurality of fan blades and the shroud cooperate to reduce a magnitude of a pressure gradient proximate to the radial gap, and to increase an impedance to air flow leakage through the radial gap from the interior portion to the fan inlet zone.

16. The fan assembly as recited in claim 12 , wherein a portion of an outer diameter of the shroud comprises a protrusion that extends radially past the radial gap between the shroud and the cover.

17. The fan assembly as recited in claim 16 , wherein a portion of an outer diameter of the shroud comprises a protrusion that extends radially past the radial gap between the shroud and the cover to obscure the radial gap and discourage air from passing through the radial gap.

18. A fan for an electronic device, the fan comprising:
a cover;
an impeller arranged to rotate around a center of rotation independent of the cover, the impeller including a ring shaped shroud that cooperates with the cover to define an interior portion of the fan, wherein the ring shaped shroud includes blades and splitter blades radially positioned around the center of rotation, each of the splitter blades having a length that is less than a length of each of the blades, wherein the ring shaped shroud is characterized by an outermost radial edge and an inner edge, wherein the ring shaped shroud is characterized by a first thickness at the inner edge and a second thickness at the outermost radial edge, and wherein the second thickness is greater than the first thickness.

19. The fan of claim 18 , wherein the ring shaped shroud and cover define a radial gap between the ring shaped shroud and the cover, wherein blades and the ring shaped shroud cooperate to reduce a magnitude of a pressure gradient proximate to the radial gap.

20. The fan of claim 18 , wherein the splitter blades are characterized as having at least two different lengths.

21. The fan of claim 18 , wherein the impeller further comprises a support disc having a smaller diameter than a diameter of the ring shaped shroud, wherein the support disc is coupled with leading edges of the blades.

22. The fan of claim 18 , wherein the shorter length of the splitter blades provides less impedance of air flow through an interior region of the impeller.

23. The fan of claim 18 , wherein the impeller comprises a blade support disc that has a center that corresponds to a center of rotation of the impeller and that is coupled with leading edges of the blades.

24. The fan of claim 23 , wherein the splitter blades have leading edges that define a diameter with respect to a center of rotation of the impeller, wherein the diameter of the leading edges of the splitter blades is larger than a diameter defined by an outer edge of the blade support disc.

Assignees

• Apple Inc

Inventors

• Dybenko Jesse T
• Aiello Anthony Joseph
• Mancini Nicholas D
• Nigen Jay S
• Naghib Lahouti Arash

Classifications

• F04D29/4226

  Fan casings · CPC title

• F04D25/0613 Primary

  the electric motor being of the inside-out type, i.e. the rotor is arranged radially outside a central stator · CPC title

• F04D29/162

  of a centrifugal flow wheel · CPC title

• G06F1/20

  Cooling means · CPC title

• F04D29/281 Primary

  for fans or blowers · CPC title