US20150167692A1

Movatterモバイル変換

Info

Publication number: US20150167692A1
Application number: US14/103,985
Authority: US
Inventors: Sukeyuki Kobayashi
Original assignee: GE Aviation Systems LLC
Current assignee: GE Aviation Systems LLC
Priority date: 2013-12-12
Filing date: 2013-12-12
Publication date: 2015-06-18

Abstract

An apparatus for a fan having an impeller with a hub and a plurality of blades extending from the hub includes a hub cap configured to mount to the hub of the impeller. The hub cap can include a plurality of slots corresponding to the blades of the impeller. The slots are sized to receive the blades when the hub cap is mounted to the hub, which shortens the working length of the blades.

Description

BACKGROUND OF THE INVENTION

Fans used in aviation systems include a case or housing and an impeller contained within the housing to create air flow. A fan is typically designed to meet specific design criteria, which may include alone or in combination any one of at least a particular air flow requirement, pressure rise, and/or rotational speed. When a new design criterion must be met, such as meeting a new air flow requirement, a new fan is designed. An existing fan can be redesigned to meet the new design criteria, such as by altering the impeller size, blade length, number of blades, etc. Often, redesigning the impeller also requires redesigning the fan housing. With any new fan design, costly new production tooling is also needed to then manufacture the fan.

BRIEF DESCRIPTION OF THE INVENTION

A fan assembly includes a fan having an impeller comprising a hub with a diameter and plurality of blades extending radially from the hub, with a distance from the hub to a tip of the blade defining a working length of the blades, and a hub cap configured to mount to the hub. The hub cap includes an end wall having a diameter larger than the diameter of the hub, a peripheral side wall extending from the end wall, and a plurality of slots corresponding to the blades and formed in the side wall. The slots are sized to receive the blades, whereby, when the hub cap is mounted to the hub, the slots receive the blades to effectively shorten the working length of the blades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fan assembly;

FIG. 2 is a partial cross-section view of the fan assembly fromFIG. 1;

FIG. 3 is a top view of an impeller from the fan assembly fromFIG. 1;

FIG. 4 is a side view of the impeller fromFIG. 3;

FIG. 5 is a top view of a hub cap useable with the fan assembly fromFIG. 1;

FIG. 6 is a side view of the hub cap fromFIG. 5;

FIG. 7 is a top view of the assembled impeller and hub cap fromFIGS. 3 and 5;

FIG. 8 is a side view of the assembled impeller and hub cap fromFIGS. 4 and 6; and

FIG. 9 is a graph showing several fan performance curves for the fan assembly fromFIG. 1 with and without the hub cap.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of afan assembly10. Thefan assembly10 includes afan12 and ahub cap14 configured to selectively mount to thefan12, as described below. Thefan12 includes animpeller16 having ahub18 with a plurality ofblades20 extending radially from thehub18. Thefan12 further includes afan housing22 which receives theimpeller16. Thefan12 is shown herein as an axial fan that increases the pressure of air flowing through it; thisfan12 is illustrated for exemplary purposes only, and thehub cap14 can be configured for use with a wide variety of fans. Thefan assembly10 can function to create air flow without or without thehub cap14.

FIG. 2 is a partial cross-section view of thefan assembly10 fromFIG. 1. Thefan assembly10 further includes amotor24 coupled to theimpeller16 via an output shaft ordrive shaft26. Thehub18 of theimpeller16 includes abore28 through which thedrive shaft26 extends. Afastener30 couples theimpeller16 to thedrive shaft26, one non-limiting example of which includes a threaded fastener or screw. Other fastening methods can also be used to attach theimpeller16 to thedrive shaft26, including other mechanical fasteners or an adhesive or bonding agent. In one arrangement, thefastener30 can be a nut which engages thedrive shaft26.

Thefan housing22 is shown herein as having a generallycylindrical side wall32, with aninlet end34 and anoutlet end36, both of which are open to permit the flow of air through thefan housing22. Theimpeller16 is positioned at theinlet end34 to draw air into thefan housing22.

FIGS. 3 and 4 are top and side views, respectively, of theimpeller16. Thehub18 includes anend wall38 and aperipheral side wall40 extending from theend wall38. Theside wall40 of thehub18 further has aperipheral edge42 opposite theend wall38.

Anopening44 to thebore28 is formed in theend wall38. More specifically, as shown herein, theend wall38 can have arecess46 in which the opening44 to thebore28 is located. Therecess46 and opening44 can be coaxially aligned along the rotational axis of theimpeller16.

The plurality ofblades20 extend radially outwardly from theside wall40, fromproximal ends48 which join theside wall40 to freedistal ends50. The number, spacing, geometry (including length, pitch, etc.) of theblades20 can vary from the configuration shown herein.

A working length L of theblades20 is generally defined by the length of theblades20 exposed to air flow. Here, without the hub cap14 (FIG. 1), the working length of eachblade20 is the distance from theproximal end48 to thedistal end50.

FIGS. 5 and 6 are top and side views, respectively, of thehub cap14. Thehub cap14 includes anend wall52 and aperipheral side wall54 extending from theend wall52. Theside wall54 of thehub cap14 further has aperipheral edge56 opposite theend wall52 that defines an open back of thehub cap14. Thehub cap14 can, for example, be made of metal, a composite material, or other suitable materials.

Anopening58 is formed in theend wall52. More specifically, as shown herein, theend wall52 can have arecess60 in which theopening58 is located. Therecess46 and opening44 can be coaxially aligned along the rotational axis of theimpeller16.

A plurality ofslots62 are formed in theside wall54. Theslots62 can extend from theperipheral edge56 toward theend wall52. As shown herein, eachslot62 can include twoopposing sides64 which extend from anopen end66 at theperipheral edge56 to a closedend68. The number, spacing, geometry (including length, pitch, etc.) of theslots62 can vary from the configuration shown herein.

FIGS. 7 and 8 are top and side views of the assembledhub cap14 andimpeller16. Thehub cap14 is received over thehub18 of theimpeller16, withblades20 received by theslots62. The opening58 of thehub cap14 is coaxially aligned with theopening44 of thehub18, and thehub cap14 is secured to thedrive shaft26 using thesame fastener30 that is used for the impeller16 (seeFIG. 2). Other fastening methods can also be used to attach thehub cap14 to theimpeller16, including other mechanical fasteners or an adhesive or bonding agent.

Therecess60 of thehub cap14 can be dimensioned to nest within therecess46 of thehub18, and the

end walls

38,52 and

side walls

40,54 of thehub cap14 andhub18 substantially align with each other so as to limit how far thehub cap14 extends beyond thehub18. By minimizing the dimensions of thehub cap14 with respect to the dimensions of thehub18, thehub cap14 can be used with an existingfan12 without modifying thefan housing22.

The slots correspond in number and size to the blades, such that the slots receive the blades when thehub cap14 is mounted to theimpeller16. The pitch and shape of theblades20 may require thehub cap14 to be rotated or twisted as the slots move over the changing shape of theblades20 to the full seated position on the impeller shown inFIGS. 7-8.

As noted above, the working length L of theblades20 is generally defined by the length of theblades20 exposed to air flow. Here, with thehub cap14 assembled with theimpeller16, the working length L of eachblade20 is the distance from theperipheral side wall54 of thehub cap14 to thedistal end50 of theblade20. Thehub cap14 thereby shortens the effective length (or span) of eachblade20 and thus alters the performance characteristics of thefan12. Conversely, thehub cap14 also effectively enlarges the working hub of thefan12.

FIG. 9 is a graph of several fan performance curves in terms of fan airflow rate (expressed in units of cubic feet per minute or CFM) and pressure rise (expressed in units of inch of water gauge or in. wg). The graph includes performance curves for thefan assembly10 with and without thehub cap14. It is noted that the various fan performance curves are shown for illustrative purposes only; the performance of thefan assembly10 shown herein may differ from the performance curves shown inFIG. 9 without departing from the embodiment of the invention discussed herein.

Line A is the performance curve for thefan assembly10 without thehub cap14 which meets a first design point X of a particular combination of airflow rate and pressure rise. Under some circumstances, such as for another application of thefan assembly10, a second or new design point Y of a different combination of airflow rate and pressure rise may be required. In some cases, thefan assembly10 may be able to meet the new design point Y by adjusting the rotational speed of theimpeller16. However, in the illustrated case, lowering the rotational speed does not result in a performance curve that meets the new design point Y. Line B is the performance curve for thefan assembly10 at approximately 90% of the rotational speed for Line A and Line C is the performance curve for thefan assembly10 at approximately 75% of the rotational speed for Line A, neither of which passes through the new design point Y.

Line D is the performance curve for thefan assembly10 with thehub cap14 mounted on theimpeller16 as shown inFIGS. 7-8. By adding thehub cap14, and in this particular case without adjusting the rotational speed of theimpeller16, the fan assembly meets the new design point Y. Adding thehub cap14 effectively enlarges the working hub of thefan assembly10 or conversely, shortens the working length L of theblades20 for the given blade diameter, so that the new design point Y can be met. Instead of making an entirely new impeller with a larger hub and shorter blades, thehub cap14 can be used.

It is noted that while the first and second design points X, Y shown inFIG. 9 have approximately the same pressure rise requirements, any combination of airflow rate and pressure rise may be required. It is also noted that while thefan assembly10 with thehub cap14 mounted on theimpeller16 as shown inFIGS. 7-8 can meet the new design point Y without adjusting rotational speed, in some cases and for some design criteria, a combination of thehub cap14 and a rotational speed change may be required.

The above described embodiments provide for a variety of benefits, including that the hub cap can be added to an existing fan in order to effectively alter the impeller configuration so that the fan can meet other performance requirements in addition to those intended with the original design of the fan. Fans can be benefited by aspects of the invention discussed herein by allowing for performance changes without requiring a new impeller; in one example, a fan with a relatively small hub diameter and relatively long blades can be provided with the hub cap in order to create a fan with a larger hub diameter and shorter blades. The hub cap does not require any special attachment or assembly since it can be secured to the existing impeller drive shaft, using the existing fastener. Rather than custom-designing a new impeller, which would otherwise be required, this apparatus and method can save time and costs in only manufacturing a new hub cap for the fan.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

What is claimed is:

1. A fan assembly comprising:

a fan having an impeller comprising a hub with a diameter and a plurality of blades extending radially from the hub, with a distance from the hub to a tip of the blade defining a working length of the blades; and

a hub cap configured to mount to the hub, comprising:

an end wall having a diameter larger than the diameter of the hub;

a peripheral side wall extending from the end wall; and

a plurality of slots corresponding to the blades and formed in the side wall;

wherein the slots are sized to receive the blades, whereby, when the hub cap is mounted to the hub, the slots receive the blades to effectively shorten the working length of the blades.

2. The fan assembly ofclaim 1 wherein the fan further comprises a motor having an output shaft, wherein the impeller is mounted to the output shaft by a fastener.

3. The fan assembly ofclaim 2, wherein the end wall of the hub cap comprises an opening which receives the fastener.

4. The fan assembly ofclaim 3, wherein the end wall of the hub cap comprises a recess, and the opening is located in the recess.

5. The fan assembly ofclaim 1, wherein the hub cap is mechanically fixed to the hub.

6. The fan assembly ofclaim 1, wherein the hub cap is bonded to the hub.

7. The fan assembly ofclaim 1 wherein the fan further comprises a fan housing, wherein the impeller and the hub cap are located within the fan housing.

8. The fan assembly ofclaim 1, wherein the plurality of blades extend radially from the hub to distal ends, and a distance between the peripheral side wall of the hub and the distal ends of the blades defines the working length of the blades.

9. The fan assembly ofclaim 1, wherein the plurality of slots are angled to correspond to a pitch of the plurality of blades where the plurality of blades meet the peripheral side wall of the hub cap.

10. The fan assembly ofclaim 9, wherein the plurality of blades extend radially from the hub to distal ends, and the pitch of the plurality of blades changes between the hub and the distal ends.

11. The fan assembly ofclaim 1, wherein the peripheral side wall of the hub cap comprises a peripheral edge opposite the end wall, wherein the plurality of slots extend from the peripheral edge toward the end wall.

12. The fan assembly ofclaim 1, wherein the hub of the impeller comprises an end wall having a diameter smaller than the diameter of the end wall of the hub cap, and a peripheral side wall extending from the end wall of the hub.

13. The fan assembly ofclaim 1, wherein the peripheral side wall of the hub extends substantially parallel to the peripheral side wall of the hub cap.