US20070231128A1

US20070231128A1 - Fan assembly

Info

Publication number: US20070231128A1
Application number: US11/394,119
Authority: US
Inventors: James Callas
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2006-03-31
Filing date: 2006-03-31
Publication date: 2007-10-04

Abstract

A fan assembly includes a fan including a plurality of fan blades, and each of the fan blades includes a tip. The fan assembly also includes a fan shroud surrounding the fan blades. The fan shroud includes a recess, and the recess includes an inner surface and at least two side surfaces. The fan assembly also includes at least one flexible member provided on at least one of the surfaces of the recess or the tips of the fan blades. At least one of a portion of the at least one flexible member or the tips of the fan blades is received in the recess.

Description

TECHNICAL FIELD

The present disclosure relates generally to a fan assembly, and more particularly, to a fan assembly with flexible members.

BACKGROUND

Engines, including diesel engines, gasoline engines, gaseous fuel-driven engines, and other engines known in the art, continually generate heat as they operate due to the combustion of fuel. Liquid coolant is circulated through the engine to remove some of the heat from the engine and to maintain engine temperatures within a safe operating range.
A radiator has a plurality of tubes configured to receive and circulate the heated coolant from the engine. A flow of ambient air is drawn through the radiator by a cooling fan so that the ambient air contacts an exterior surface of the coolant-carrying tubes of the radiator. The ambient air flows through spaces between the radiator tubes and across the radiator tubes, thereby removing some of the heat from the coolant that is flowing through the radiator tubes. The coolant is at least partly cooled in this manner and is then returned to the engine.
The cooling fan is typically positioned adjacent a rear side of the radiator to draw the flow of ambient air over the radiator tubes. A fan shroud is typically positioned between the cooling fan and the radiator to assist in directing the air flow through the radiator. The fan shroud surrounds blades of the cooling fan. In some conventional cooling fans, there is a clearance of approximately 0.625 to 0.75 inches (15.875 to 19.05 millimeters) between the tips of the fan blades and the fan shroud to prevent the tips of the fan blades from contacting the fan shroud, which would damage one or more of the components and/or create fan noise. Due to the large clearance between the tips of the fan blades and the fan shroud, the cooling fan efficiency is reduced.
One example of a cooling fan and a fan shroud is described in U.S. Pat. No. 6,508,624 (“the '624 patent”) issued to Nadeau et al. The '624 patent describes a cooling fan with a plurality of blades that are each connected at the tips to an annular band. The annular band is disposed within a gap formed between two opposing surfaces of a fan shroud. The annular band includes a radially extending wall disposed in the fan shroud gap and an axially extending wall coupled to the radially extending wall and to the blade tips. Bristles may be provided on the fan shroud in the gap.
The system of the '624 patent may provide a fan shroud for directing air flow from a cooling fan. However, the annular band connecting the tips of the fan blades increases the cost and the complexity of the design and construction of the cooling fan. The annular band must be constructed so that it does not contact the fan shroud significantly along its entire circumference. Furthermore, since the annular band includes both an axially extending wall and a radially extending wall, and both of these walls are positioned near opposing surfaces of the fan shroud, there is an increased chance that one or both of these walls may contact one or more of the opposing surfaces of the fan shroud, thereby damaging the fan shroud or the annular band and/or causing fan noise.
The disclosed system is directed to overcoming one or more of the problems set forth above.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure is directed to a fan assembly including a fan including a plurality of fan blades. Each of the fan blades includes a tip. The fan assembly also includes a fan shroud surrounding the fan blades. The fan shroud includes a recess, and the recess includes an inner surface and at least two side surfaces. The fan assembly also includes at least one flexible member provided on at least one of the surfaces of the recess or the tips of the fan blades. At least one of a portion of the at least one flexible member or the tips of the fan blades is received in the recess.
In another aspect, the present disclosure is directed to a fan assembly configured to draw air flow through a radiator associated with an engine. The fan assembly includes a fan including a plurality of fan blades, and each of the fan blades includes a tip. The fan assembly also includes a fan shroud surrounding the fan blades, at least one spring on each of the tips of the fan blades, and a cover for covering the at least one spring. The cover is attached to the spring.
In yet another aspect, the present disclosure is also directed to a fan assembly configured to draw air flow through a radiator associated with an engine. The fan assembly includes a fan including a plurality of fan blades, and each of the fan blades includes a tip. The fan assembly also includes a fan shroud surrounding the fan blades, and the fan shroud includes a recess. The recess includes an inner surface and at least two side surfaces. The fan assembly also includes a plurality of fibers provided on at least one of the surfaces of the recess or the tips of the fan blades, and at least a portion of the fibers are received in the recess.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an engine, a cooling fan, a fan shroud, and a radiator according to an exemplary embodiment;
FIG. 2 is a cross-sectional view of a cooling fan and fan shroud according to an exemplary embodiment;
FIG. 3 is a cross-sectional view of a blade of the cooling fan and fan shroud of FIG. 2;
FIG. 4 is a cross-sectional view of a blade of a cooling fan and fan shroud according to yet another exemplary embodiment;
FIG. 5 is a cross-sectional view of a blade of a cooling fan and fan shroud according to a further exemplary embodiment; and
FIG. 6 is a cross-sectional view of a blade of a cooling fan and fan shroud according to a further exemplary embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
As shown in FIG. 1, a power source, such as an engine 10, is provided. The engine 10 may be, for example, an internal combustion engine of the diesel, gasoline, or gaseous fuel-driven type, or any other type of engine. The engine 10 is positioned near a radiator 50 or other heat exchanger connected using a hose to a coolant reservoir 52. The radiator 50 receives heated coolant from the engine 10 via a first fluid passageway 54 and returns at least partially cooled coolant to the engine 10 via a second fluid passageway 56.
A fan assembly 18 includes a cooling fan 20 and a fan shroud 30. The cooling fan 20 is positioned adjacent to the radiator 50 and includes a shaft 12 that is connected to the engine 10 so that the engine 10 transfers rotational motion to the cooling fan 20. The cooling fan 20 includes fan blades 22 that may have any structure operable to drive or draw air through the tubes of the radiator 50. For example, the fan blades 22 may be propeller-like blades or another type of blade known in the art. Each of the fan blades 22 may be formed of plastic or metal, as is known in the art.
The fan shroud 30 encircles the fan blades 22 and is also positioned adjacent to the radiator 50. The fan shroud 30 may be formed of plastic, metal, or other rigid material, as is known in the art. The fan shroud 30 surrounds the cooling fan 20 circumferentially so that a tight tip clearance is provided between the tips 24 of the fan blades 22 and the fan shroud 30. The tip clearance may be small and may vary according to the application.
Referring to FIGS. 2 and 3, an exemplary fan shroud 30 includes an annular recess 32 that is formed by an inner surface 33 and two side surfaces 34. The tips 24 of the fan blades 22 are enclosed in the recess 32 between the inner surface 33 and the two side surfaces 34. The depth of the recess 32, i.e., the lengths of the side surfaces 34, may vary. For example, in some exemplary embodiments, the depth of the recess 32 may range from 1/20^thto 1/10^thof the total blade length. Alternatively, the recess 32 may be omitted, and an inner surface of the fan shroud 30 may be formed as a single curved or flat surface (not shown).
A mat 42 of fibers 40 may be adhered to the entire inner surface 33 and the entire two side surfaces 34 of the recess 32 using glue or other adhesive substances. The fibers 40 may be made of carbon fiber, plastic, nylon, polyethylene, rubber, and/or other flexible and durable material. The fibers 40 may be woven and/or adhered to the mat 42, as known in the art. The height of the fibers 40 and the density of the mat 42 may vary depending on the application. Alternatively, if the recess 32 is omitted, the mat 42 of fibers 40 may be adhered to the entire surface of the fan shroud 30 facing the fan blades 22. As another alternative, the mat 42 of fibers 40 may be adhered to only the inner surface 33 or only a portion of the inner surface 33 and/or the side surfaces 34 or only a portion of the side surfaces 34 of the recess 32.
In the exemplary embodiment shown in FIG. 4, the fibers 40 may also be provided on the tip 24 and/or on at least a portion of side edges 25 of the fan blades 22. As another alternative, the fibers 40 may be provided only on the tip 24 and/or the side edges 25 of the fan blades 22, but not on the fan shroud 30. Alternatively, the fibers 40 may be provided on only a portion of the tip 24 of each fan blade 22.
The fibers 40 may be integrally formed on the tips 24. For example, the fan blades 22 may be made of a rigid fibrous material, such as nylon or nylon reinforced with carbon fiber, having fibers 40 extending from the surface of the fan blades 22. The surface of the fan blade 22, except for the tips 24, may be coated with a resin or other substance to bind together the fibers at the surface. Since the resin does not coat the tips 24, the fibers 40 may extend from the surface of the uncoated tips 24. Alternatively, the fibers 40 on the fan blade tips 24 may be separate from the fan blade 22 and may be attached to the fan blade tips 24 using an adhesive substance.
In the exemplary embodiment shown in FIG. 5, one or more springs 26 are attached to each of the tips 24 of the fan blades 22. Each of the springs 26 has one end attached to the tip 24 of the fan blades 22 and another end attached to a cover 28. The cover 28 may extend over a portion of the adjacent fan blade tip 24. The cover 28 may be formed of a flexible and durable material, such as carbon fiber, plastic, nylon, polyethylene, and/or rubber, and is provided for covering one or more of the springs 26. The number of springs 26 provided on each tip 24 of the fan blades 22 depends on the width of the blades 22. Alternatively, the embodiment of FIG. 5 may also include fibers 40 provided on the fan shroud 30, as described above in connection with FIGS. 2 and 3.
In the exemplary embodiment shown in FIG. 6, instead of adhering fibers 40 to the tip 24 of the fan blade 22 (FIG. 4), an edge portion 29 may be attached using an adhesive substance, such as glue, to the tip 24 to reduce the tip clearance. The edge portion 29 may be a flexible member made of, e.g., carbon fiber, plastic, nylon, polyethylene, and/or rubber, that may extend along the entire length, or a portion thereof, of the fan blade tip 24. According to the above described embodiments, the clearance between the fan shroud 30 (or the fibers 40 thereon) and the fan blade tips 24 (or the fibers 40, flexible edge portion, or covered spring 26 thereon) may be 9 millimeters (0.354 inches) or less.

INDUSTRIAL APPLICABILITY

The disclosed fan assembly 18 may be provided in any machine that generates heat and may be used for a variety of applications. For example, the fan assembly 18 may be provided in a prime-mover, vehicle, or the like, or any type of machine requiring mechanical or electrical energy. Such machines may include, but are not limited to, earth moving machines, backhoes, graders, rock crushers, pavers, skid-steer loaders, cranes, automobiles, trucks, and the like.
Heated coolant is transferred from the engine 10 to the radiator 50 to circulate through tubes of the radiator 50. The flow of ambient air (indicated by arrows A in FIG. 1) is drawn through the radiator 50 by the cooling fan 20 so that the ambient air contacts an exterior surface of the coolant-carrying tubes of the radiator 50. The coolant is at least partly cooled in this manner and is then returned to the engine 10.
The fan shroud 30 directs the flow of ambient air from the radiator 50 to the cooling fan 20. As shown in FIGS. 2-6, the size and shape of the fan shroud surfaces 33, 34 facing the fan blades 22 are configured so that there is a tight tip clearance between the fan shroud surfaces 33, 34 and the tips 24 of the fan blades 22. With a tighter tip clearance, more air may be drawn through the cooling fan 20, thereby increasing fan efficiency.
The fibers 40 (FIGS. 2-4 and 6) provided on the fan shroud surfaces 33, 34 and the fibers 40 provided on the fan blades 22 (FIG. 4) act as flexible members that allow the tighter tip clearance. Also, if any anomalies during fan operation cause the fan blades 22 to contact the fan shroud 30, the fibers 40 may act as cushioning to reduce noise and/or abrasion of the tips 24 of the fan blades 22 against the fan shroud surfaces 33, 34. The fibers 40 may be capable of bending when contacting the fan shroud 30 or fan blade 22 and then returning to their original position after moving away from the fan shroud 30 or fan blade 22.
The tips 24 of the fan blades 22 are positioned in the recess 32 of the fan shroud 30 so that the tips 24 are surrounded on three edges 24, 25 by the inner surface 33 and the two side surfaces 34 of the recess 32. As a result, there is more surface area of the fan shroud 30 surrounding the tips 24 of the fan blades 22, and this surface area may be covered by the fibers 40 to provide a tighter clearance around the three edges 24, 25 of the fan blade 22. As a result, more air is circulated by the fan blades 22, and the fibers 40 may act as cushioning to reduce noise and/or abrasion if the tips 24 of the fan blades 22 contact the fan shroud 30 and may reduce or prevent a leakage of air from a pressure side to a suction side of the fan blades 22, thereby increasing fan efficiency.
Referring to FIG. 4, the fibers 40 are also provided on the tips 24 and side edges 25 of the fan blades 22. Thus, an even tighter clearance may be provided around the three edges 24, 25 of the fan blade 22. As a result, more air is circulated by the fan blades 22, and the fibers 40 may act as cushioning to reduce noise and/or abrasion if the tips 24 of the fan blades 22 contact the fan shroud 30.
Referring to FIG. 5, the covered spring 26 acts as a spring-loaded tip at the end of each fan blade 22. The cover 28 prevents the spring 26 from contacting the fan shroud 30 directly, and the springs 26 are capable of expanding and contracting, thereby causing the cover 28 to move with respect to the fan blades 22, as indicated by arrow B. As a result, the spring 26 and the cover 28 form a flexible member that allows an even tighter clearance. More air may be circulated by the fan blades 22. Furthermore, if the fan blades 22 move with respect to the fan shroud 30 so that one or more tips 24 move toward the fan shroud 30, the cover 28 contacts the fan shroud 30 first, thereby causing the spring 26 to compress and minimizing damage to any of the contacting parts. The spring 26 may then return to its original position after the tips 24 move away from the fan shroud 30.
Referring to FIG. 6, the edge portion 29 acts as a flexible tip at the end of each fan blade 22. The edge portion 29 is capable of bending and moving with respect to the fan blades 22, for example, when contacting the fan shroud 30. As a result, the edge portion 29 forms a flexible member that allows an even tighter tip clearance, and more air may be circulated by the fan blades 22. Furthermore, if the fan blades 22 move with respect to the fan shroud 30 so that one or more tips 24 move toward the fan shroud 30, the edge portion 29 may contact the fan shroud 30 and bend. The flexibility of the edge portion 29 minimizes damage to any of the contacting parts. The edge portion 29 may then return to its original position after the tips 24 move away from the fan shroud 30.
As provided above, a fan assembly 18 in accordance with the exemplary embodiments may include a fan 20, a rigid fan shroud 30, and one or more flexible members, such as fibers 40, an edge portion 29, or a covered spring 26, 28, that reduces tip abrasion or other damage to the components of the fan assembly 18, such as the fan shroud 30 or the fan blades 22. The one or more flexible members form a seal so that there is a minimal clearance between the tips of the fan blades and the fan shroud. When fibers are attached to the fan shroud or when fibers, an edge portion, or a covered spring are attached to the fan blade, there may be an even smaller (or zero) clearance. With a smaller clearance, fan efficiency may be increased since more air may be pushed by the fan blades and directed through the fan shroud. Fan noise may be reduced since the fibers or other flexible members may absorb any noise created by any of the moving parts in the fan. Furthermore, fan damage or noise that may be caused by any anomalies during fan operation that cause the fan blades to contact the fan shroud may be minimized.
The fan assembly has a design that is easy to manufacture. Also, there are fewer possible contact points between the fan blades and the fan shroud (i.e., near the fan blade tips), thereby reducing the possibility of damage to any of the components or fan noise.
Further, a fan shroud in accordance with the exemplary embodiments may include a recess 32 in which the tips 24 of the fan blades 22 are positioned. As a result, more surface area of the fan shroud may be covered by the fibers, thereby creating a better seal having minimal clearance between the tips of the fan blades and the fan shroud. With a better seal, there is greater resistance to air flow in the clearance and there is a reduction or prevention of the leakage of air from the pressure side to the suction side of the fan blades, thereby maximizing the amount of air flow drawn by the fan blades.
It will be apparent to those skilled in the art that various modifications and variations can be made to the fan assembly. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed fan assembly. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.

Claims

1. A fan assembly comprising:

a fan including a plurality of fan blades, each of the fan blades including a tip;

a fan shroud surrounding the fan blades, the fan shroud including a recess, the recess including an inner surface and at least two side surfaces; and

at least one flexible member provided on at least one of the surfaces of the recess or the tips of the fan blades, at least one of a portion of the at least one flexible member or the tips of the fan blades being received in the recess.

2. The fan assembly of claim 1, wherein the at least one flexible member includes a plurality of fibers.

3. The fan assembly of claim 2, wherein the fibers are attached to a mat, the mat being adhered to the at least one of the surfaces of the recess or the tips of the fan blades.

4. The fan assembly of claim 2, wherein the plurality of fibers are provided on the inner surface and the side surfaces of the recess.

5. The fan assembly of claim 4, wherein the plurality of fibers are provided on the entire inner surface and the entire side surfaces of the recess.

6. The fan assembly of claim 2, wherein the fan blades further include side edges, and the plurality of fibers are provided on at least a portion of the side edges of the fan blades and the tips of the fan blades.

7. The fan assembly of claim 6, wherein the plurality of fibers provided on the fan blades are integrally formed with the fan blades.

8. The fan assembly of claim 6, wherein the plurality of fibers are provided on the inner surface and the side surfaces of the recess.

9. The fan assembly of claim 1, wherein the at least one flexible member includes at least one spring on each of the tips of the fan blades, and a cover for covering the at least one spring.

10. The fan assembly of claim 9, wherein at least a portion of the cover is received in the recess of the fan shroud.

11. The fan assembly of claim 9, wherein a plurality of fibers are provided on the inner surface and the side surfaces of the recess.

12. The fan assembly of claim 1, wherein the at least one flexible member includes a flexible edge section.

13. The fan assembly of claim 1, wherein the at least one flexible member is formed of at least one of carbon fiber, plastic, nylon, polyethylene, or rubber.

14. A fan assembly configured to draw air flow through a radiator associated with an engine, the fan assembly comprising:

a fan shroud surrounding the fan blades;

at least one spring on each of the tips of the fan blades; and

a cover for covering the at least one spring, the cover being attached to the spring.

15. The fan assembly of claim 14, wherein the fan shroud includes a recess in which at least a portion of each of the covers is received.

16. The fan assembly of claim 14, wherein the cover extends over the tip of the associated fan blade.

17. A fan assembly configured to draw air flow through a radiator associated with an engine, the fan assembly comprising:

a plurality of fibers provided on at least one of the surfaces of the recess or the tips of the fan blades, at least a portion of the fibers being received in the recess.

18. The fan assembly of claim 17, wherein the plurality of fibers are attached to at least one mat, the at least one mat being adhered to the inner surface and the side surfaces of the recess.

19. The fan assembly of claim 17, wherein the fan blades further include side edges, and the plurality of fibers are provided on at least a portion of the side edges of the fan blades and the tips of the fan blades.

20. The fan assembly of claim 19, wherein the plurality of fibers provided on the fan blades are integrally formed with the fan blades.