Ring cooling fan including stiffening ribs fully connected on at most two sides

Abstract

A process of producing a ring cooling fan, the ring cooling fan including at least two fan blades, a fan hub, and a fan ring. Each of the fan blades has a distal end disposed away from the fan hub and connected with one another via the fan ring and a proximal end disposed on the fan hub. At least one of the fan blades includes at least two stiffening ribs in an open-box structure. The process includes disposing the fan hub in a mold, molding the at least two fan blades and the fan ring such that the stiffening ribs are disposed on a top surface of the fan blade and are fully connected with each other on at most two sides, and removing the ring cooling fan from the mold.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a ring cooling fan, and, more specifically, to a ring cooling fan including stiffening ribs fully connected on at most two sides (e.g., stiffening ribs having an open-box structure with more than one full side open, such that excess material is absent from a full top side and at least a portion of another side of the stiffening ribs structure).

BACKGROUND OF THE INVENTION

[0002] In an internal combustion engine (e.g., a diesel or a gasoline engine), a ring cooling fan including multiple fan blades or impellers that draw and/or push air through a heat conducting radiator can be used to regulate the temperature of an engine coolant that cools the engine. As the performance level of the engine increases and/or the size of the engine compartment that houses the fan decreases, cooling requirements of the fan increase.

[0003] The revolution rate of the fan blades can be increased to increase the cooling rate of the engine coolant. However, because a fan that is revolved at a higher rate undergoes increased stresses and strains, the fan can warp or suffer catastrophic failure or “bursting” during operation, significantly and adversely affecting engine performance.

[0004] To avoid such adverse effects, stiffened portions in the form of a closed-box structure can be used on the fan blades at a location where the fan blades are molded on a center fan hub. In conjunction with the outer ring, such portions prevent warpage and bursting of the blades of the ring fan over a larger range of operating conditions and at higher rates of revolution. FIGS. 5a and 5b show an example of such a ring fan. As exemplified in FIGS. 5a and 5b, the ring fan 10 includes stiffeners 20 that are configured as the closed-box structure, such that the stiffeners 20 are fully connected on at least three sides (e.g., each of the two stiffeners 20 and the three connecting sides forms a full face of a cuboid structure), thereby forming a box that has only one side open. It has been found that such a closed-box structure 20 permits operation of the ring fan 10 at higher rates of revolution than a ring fan without such a structure while substantially impeding warpage and bursting of the blades 30.

[0005] The ring fan 10 is produced by an injection molding process. In such a process, the number of fans that can be produced by a single molding machine is proportional to the process time for injection of the molten plastic and cooling of the injection molded part. Accordingly, it is desirable to reduce the cooling time for the fan produced by a molding machine. For these reasons, it is desirable to produce a ring fan that is sufficiently rigid to preclude warpage and bursting during operation, while at the same time decreasing the cooling time and thereby allowing the ring fan to be produced in a more economical manner.

SUMMARY OF THE INVENTION

[0006] The present invention provides a process of producing a ring cooling fan, the ring cooling fan including at least two fan blades, a fan hub, and a fan ring. Each of the fan blades has a distal end disposed away from the fan hub and connected with one another via the fan ring and a proximal end disposed on the fan hub. At least one of the fan blades includes at least two stiffening ribs in an open-box structure. The process includes disposing the fan hub in a mold, molding the at least two fan blades and the fan ring such that the stiffening ribs are disposed on a top surface of the fan blade and are fully connected with each other on at most two sides, and removing the ring cooling fan from the mold. In a preferred embodiment, the stiffening ribs and the at most two connecting sides each form full faces of a cuboid structure, thereby forming the open-box structure that is open on more than one full side (e.g., open on one full side and at least a portion of another side), and more preferably, is open on two full sides. The stiffening ribs are preferably connected with or to each other via the structure of the fan blades. The present invention also provides a ring cooling fan produced by such a process.

[0007] The present invention further provides a ring cooling fan. A fan hub includes a top surface and a bottom surface disposed apart from the top surface along an axis of rotation of the ring cooling fan for connection with a drive shaft or clutch body. A first fan blade includes a first distal end and a first proximal end opposite the first distal end and connected with a fan hub. A second fan blade includes a second distal end and a second proximal end opposite the second distal end and connected with the fan hub, the first and second distal ends of the fan blades being connected with each other via the fan ring. At least two stiffening ribs are disposed on the first fan blade in an open-box structure, the stiffening ribs being fully connected with each other on at most two sides. In a preferred embodiment, the stiffening ribs and the at most two connecting sides each form full faces of a cuboid structure, thereby forming the open-box structure that is open on more than one full side (e.g., open on one full side and at least a portion of another side), and more preferably, is open on two full sides.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0009] FIG. 1 shows a bottom isometric view of the ring cooling fan of the present invention.

[0010] FIG. 2 shows a detail isometric view of the bottom of the ring cooling fan.

[0011] FIG. 3 shows a top view of the ring cooling fan.

[0012] FIG. 4 shows a detail isometric view of the top of the ring cooling fan.

[0013] FIGS. 5a and 5b show top and bottom views, respectively, of a ring cooling fan having a closed-box structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Examples of preferred embodiments of the present invention will now be described with reference to the drawings, wherein like reference numbers throughout the several views identify like elements. FIGS. 1-4 show an example of a ring cooling fan according to the present invention.

[0015] In a broad embodiment, the ring cooling fan 10 includes stiffening ribs 20 that are disposed on a surface of a fan blade 40 and fully connected with each other on at most two sides, such that two stiffening ribs 20 and the at most two connecting sides (e.g., other structure of the ring cooling fan 10) each form a full face of a cuboid structure, thereby forming an open-box structure that is open on more than one full side (e.g., open on one full side and at least any non-zero portion of another side). In a preferred embodiment, two sides of the open-box structure are fully open. However, it is to be understood that the open-box structure includes, for example, the structure that is open on one full side and that is open on another side at least between about 10 and 100 percent (i.e., is closed between about 0 and 90 percent) of a corresponding length of at least one of the stiffening ribs. In a more preferred embodiment, the open-box structure is open on one full side and is open on another side at least between about 50 and 100 percent (i.e., is closed between about 0 and 50 percent), and, in a still more preferred embodiment, is open on the other side between about 75 and 100 percent (i.e., is closed between about 0 and 25 percent). However, it is to be understood that the open-box structure includes the structure that is open on one full side and that is open on another side within any ranges and/or subranges discussed above. Disposing the stiffening ribs 20 on the surface of the fan blade 40 is to be understood to include the use of at least one surface of the fan blade 40 as the connecting side so as to preclude requiring additional structural features (e.g., an additional rib attachment ring) between the at least one surface of the fan blade 40 and the stiffening ribs 20. By this arrangement, excess structure associated with an additional attachment ring, for example, can be eliminated. This arrangement results in a reduced volume of plastic between successive fan blades 40 and/or between the stiffening rib 20 and the fan blade 40. In a preferred embodiment, the stiffening ribs 20 are disposed on the surface of the fan blade 40 that is parallel to an axis of rotation of the ring cooling fan 10. Fully connected stiffening ribs 20 are to be understood to include a connection between at least a portion of a length of the stiffening rib 20 and a full length of the connecting side, as well as a full length of the stiffening rib 20 and at least a portion of the length of the connecting side. Such an arrangement facilitates removal of the ring cooling fan 10 from a mold during a molding process, decreases cooling time in the mold of the ring cooling fan 10 during the injection molding process, and/or prevents sticking and pull-outs of the stiffening ribs 20.

[0016] As exemplified in the drawings, the preferred ring cooling fan 10 includes the stiffening ribs 20, a fan hub 30, a plurality (i.e., at least two (2), preferably six (6), and more preferably ten (10) or more) of the fan blades 40, and a fan ring 50 (each discussed below).

[0017] In a broad embodiment, the fan hub 30 couples the fan blades 40 with a ring cooling fan drive shaft (not shown) or clutch body (not shown). By this arrangement, a rotation of the drive shaft or clutch body results in a corresponding revolution of the fan blades 40/ring cooling fan 10. It is to be understood that although the fan hub 30 and its associated structure shown in the drawing figures exemplifies preferred embodiments, the fan hub 30 can include any structure so long as the fan hub 30 couples with the fan blades 40 for rotation.

[0018] As exemplified in the drawings, the fan hub 30 has a top surface 31 and a bottom surface 33 that is offset from the top surface 31 along an axis of rotation of the fan hub 30/the ring cooling fan 10. Each of the top and bottom surfaces 31, 33, have a generally circular cross section, and include portions that are disposed on successive parallel planes (i.e., neither of the top and bottom surfaces 31, 33, are required to lie entirely on a single plane). By this arrangement, in a preferred embodiment, the fan hub 30 is generally cup-shaped.

[0019] As exemplified in the figures, a plurality of about-circular holes 35 is used to connect the fan hub 30 with the drive shaft or clutch body. The plurality of about-circular holes 35 is preferably about equally spaced on the fan hub 30. In a preferred embodiment, the plurality of about-circular holes 35 includes four (4) holes that are disposed about 90 degrees apart. The fan hub 30 can also include a plurality of radial slots 37. The radial slots 37 permit dissipation of heat from the clutch body. The plurality of radial slots 37 is about equally spaced on the fan hub 30. In a preferred embodiment, the plurality of radial slots 37 includes four (4) slots that are disposed about 90 degrees apart.

[0020] Optionally, the fan hub 30 can include interface holes (not shown) disposed on an outer diameter thereof. The interface holes can be used for flow through of liquid plastic during the molding process. By this arrangement, the fan blades 40 can be secured to the fan hub 30. In a preferred embodiment, the fan hub 30 includes thirty six (36) such interface holes, each having a diameter of between 11 and 12 mm. However, it is to be understood that the any number of interface holes of any size can be disposed at a variety of positions on along the diameter of the fan hub 30. It is to be further understood that satisfactory attachment of the fan blades 40 with the fan hub 30 can be achieved in the absence of interface holes on the fan hub 30.

[0021] The fan hub 30 can be of a variety of materials, including plastics and metals. In a preferred embodiment, the fan hub 30 is a metal capable of being disposed in a mold, such that at least a portion of the ring cooling fan 10 can be molded directly thereon. Specifically, the material can be steel, such as 050 YHK hot roll steel, aluminum, or glass filled nylon. However, it is to be understood that the fan hub 30 can be of any material able to substantially impede bursting under the desired operating conditions of the ring cooling fan 10.

[0022] In a broad embodiment, the plurality (i.e., at least two) of the fan blades 40 is connected with the fan hub 30, such that the fan blades 40 effectively cool the engine. As exemplified in the drawings, in a preferred embodiment, the plurality of fan blades 40 includes ten (10) fan blades 40. It is to be understood that although the fan blades 40 and their associated structure shown in the drawing figures exemplify preferred embodiments, the fan blades 40 can include any structure so long as the fan blades 40 effectively cool the engine.

[0023] As exemplified in the drawings, each of the fan blades 40 includes a proximal end 41 and a distal end 43 that is disposed apart from the proximal end 41. Contours of the top blade surface 45 and the bottom blade surface 47 are selected based on the desired operating conditions and cooling requirements of the ring cooling fan 10. As exemplified in the figures, at least two, and preferably, all of the distal ends 43 of the fan blades 40 are connected to each other via the fan ring 50.

[0024] In a broad embodiment, the fan ring 50 connects at least two of the fan blades 40, thereby permitting desired operation of the ring cooling fan 10. Although the drawings show preferred embodiments of the fan ring 50 having a rectangular cross section and connecting each of the distal ends of the fan blades 40, it is to be understood that the fan ring 50 can be of any cross-sectional shape, and can connect any of a plurality (i.e., at least two) of the fan blades 40 at any location along the length of the fan blades 40.

[0025] In a broad embodiment, the stiffening ribs 20 are disposed on a surface of a fan blade 40 and fully connected to each other on at most two sides, such that two stiffening ribs 20 and at most two connecting sides form full faces of the cuboid structure, thereby forming an open-box structure that is open on more than one full side (e.g., open on one full side and at least a portion of another side, and preferably open on two full sides). As discussed above, disposing the stiffening ribs 20 on the surface of the fan blade 40 is to be understood to include the use of at least one surface of the fan blade 40 as the connecting side so as to preclude requiring additional structural features (e.g., an additional rib attachment ring) between the at least one surface of the fan blade 40 and the stiffening ribs 20. For example, as shown in the drawings, in a preferred embodiment, the stiffening ribs 20 are connected with or to each other via a side surface of the fan blades 40, the side surface being parallel to the axis of rotation of the ring cooling fan 10. The open-box structure including stiffening ribs disposed on the surface of the fan blades provides a number of advantages over a closed-box structure having a single open side as depicted in FIGS. 5a and 5b. It is believed that the closed-box structure acts as an insulator by restricting heat flow away from features of the mold. The open-box structure reduces cooling time and therefore process cycle time by increasing heat flow away from the features of the mold. Thus, by this arrangement, removal of the ring cooling fan 10 from the mold is facilitated, cooling time in the mold of the ring cooling fan 10 during the injection molding process is decreased, and/or sticking and pull-outs of the stiffening ribs 20 is prevented. Generally, it is believed that these advantages are inversely proportional to a size of a wall formed on the open sides of the open-box structure (i.e., that these advantages decrease when the open-box structure is open on one full side and a relatively small portion of another side), and therefore are maximized when both sides of the open-box structure are fully open.

[0026] As exemplified in the drawings, in a preferred embodiment, the stiffening ribs 20 are used on both top and bottom surfaces of the ring cooling fan 10. However, it is to be understood that the stiffening ribs 20 can be used on either or both sides of the fan blades 40.

[0027] In a preferred embodiment exemplified in the drawings, the top stiffening ribs 21 extend from the top surface 31 of the hub ring 30 to the top blade surface 45 along the axis of rotation of the ring cooling fan 10 and extend along a radius of the fan hub 30/the ring cooling fan 10 to an edge of the proximal end of the fan blade 40. The heights of the top stiffening ribs 21 can vary from each other, such that each of the top stiffening ribs 21 has a different height, and are preferably arranged in order of ascending or descending height. The number, size, shape, spacing, orientation, and material of the top stiffening ribs 21 can be selected such that the desired characteristics of the ring cooling fan 10 are achieved. For example, one or more of the top stiffening ribs 21 can be disposed at an angle to the radius of the fan hub 30, and one or more of the top stiffening ribs 21 can be disposed about parallel with at least one other top stiffening rib 21. Alternatively, all of the top stiffening ribs 21 can be disposed in any orientation, and can be disposed in different orientations relative to one another. Further, any number of the top stiffening ribs 21 can be used. In a preferred embodiment, three (3) to six (6) such top stiffening ribs 21 are used, and more preferably four (4) such top stiffening ribs 21 are used.

[0028] Similarly, bottom stiffening ribs 23 preferably extend from the bottom surface 33 to the bottom blade surface 47 along the axis of rotation of the ring cooling fan 10 and extend along the radius of the hub ring 30/the ring cooling fan 10 to the edge of the proximal end of the fan blade 40. The heights of the bottom stiffening ribs 23 can vary from each other, such that each of the bottom stiffening ribs 23 has a different height, and are preferably arranged in order of ascending or descending height. The number, size, shape, spacing, orientation, and material of the bottom stiffening ribs 23 can be selected such that the desired characteristics of the ring cooling fan 10 are achieved. For example, one or more of the bottom stiffening ribs 23 can be disposed at an angle to the radius of the fan hub 30, and one or more of the bottom stiffening ribs 23 can be disposed about parallel with at least one other bottom stiffening rib 23. Alternatively, all of the bottom stiffening ribs 23 can be disposed in any orientation, and can be disposed in different orientations relative to one another. Further, any number of the bottom stiffening ribs 23 can be used. In a preferred embodiment, one or a plurality (i.e., at least two) of such stiffening ribs 23 are used. When a plurality of stiffening ribs 23 are used, preferably two (2) to six (6) such stiffening ribs 23 are used, and more preferably two (2) such stiffening ribs 23 are used.

[0029] Various other structural and material characteristics of the stiffening ribs 20 can be selected, in conjunction with the material and characteristics of the fan hub 30, such that undesired warpage and bursting of the ring cooling fan 10 is substantially impeded.

[0030] As discussed above, the ring cooling fan 10 is preferably manufactured by an injection molding process. In such a process, the fan hub 30 is disposed in the mold. A feed stock is mixed, heated to a melt point, and injected at a specified pressure into the closed mold to completely fill the mold. During the injection process, the fan blades 40 and the fan ring 50 are molded on the fan hub 30. At least two stiffening ribs 20 are molded on at least one of the fan blades 40, such that the stiffening ribs 20 are connected with each other on at most two sides, and, in a more preferred embodiment, such that the stiffening ribs 20 are fully connected on at most two sides (e.g., the two stiffening ribs 20 and at most two connecting sides each form full faces of the cuboid structure, thereby forming an open-box structure that is open on more than one full side). The filled mold enters the cooling phase of the injection molding process, wherein the melted plastic solidifies (i.e., changes from a liquid state to a solid state). The mold is opened, and the ring cooling fan 10 is ejected therefrom by one or more ejection pins. Thus, the present invention includes a ring cooling fan 10 produced by such a process, as well as a ring cooling fan 10 including the open-box structure produced by a different process.

[0031] Numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.

Claims

1. A process of producing a ring cooling fan, the ring cooling fan comprising at least two fan blades, a fan hub, and a fan ring, each of the fan blades having a distal end disposed away from the fan hub and connected with one another via the fan ring and a proximal end disposed on the fan hub, at least one of the fan blades including at least two stiffening ribs, the process comprising:

disposing the fan hub in a mold;

molding the at least two fan blades and the fan ring, such that the stiffening ribs are disposed on a surface of the fan blade and are fully connected with each other on at most two sides; and

removing the ring cooling fan from the mold.

2. The process according to claim 1, wherein the stiffening ribs are disposed along a radius of the fan hub.

3. The process according to claim 1, wherein the stiffening ribs are disposed at an angle to a radius of the fan hub.

4. The process according to claim 3, wherein the stiffening ribs are substantially parallel with each other.

5. The process according to claim 1, wherein the stiffening ribs have an open-box structure which is open on two full sides.

6. The process according to claim 1, wherein four stiffening ribs are present.

7. The process according to claim 1, further comprising:

molding at least two additional stiffening ribs on the surface of at least one fan blade opposite the surface on which the original stiffening ribs are disposed.

8. A ring cooling fan produced by the process of claim 1.

9. A ring cooling fan produced by the process of claim 5.

10. A ring cooling fan produced by the process of claim 6.

11. A ring cooling fan, comprising:

a fan ring;

a fan hub comprising a top surface and a bottom surface disposed apart from the top surface along an axis of rotation of the ring cooling fan for connection with a drive shaft or clutch body;

a first fan blade including a first distal end and a first proximal end opposite the first distal end and connected with the fan hub;

a second fan blade including a second distal end and a second proximal end opposite the second distal end and connected with the fan hub, the first and second distal ends of the fan blades being connected with each other via the fan ring; and

at least two stiffening ribs disposed on the first fan blade, the stiffening ribs being fully connected with each other on at most two sides.

12. The ring cooling fan according to claim 11, wherein at least one of the stiffening ribs extends along a radius of the fan hub.

13. The ring cooling fan according to claim 11, wherein at least one of the stiffening ribs extends at an angle to a radius of the fan hub.

14. The ring cooling fan according to claim 11, wherein the stiffening ribs are parallel with each other.

15. The ring cooling fan according to claim 11, wherein the first fan blade includes a fan blade top surface disposed at a blade angle from and adjacent to the top surface of the fan hub, the stiffening ribs extending from the fan blade top surface to the top surface of the fan hub.

16. The ring cooling fan according to claim 15, wherein four stiffening ribs are present.

17. The ring cooling fan according to claim 16, further comprising:

at least one bottom stiffening rib disposed on a bottom surface of the first blade opposite the top surface.

18. The ring cooling fan according to claim 17, wherein two stiffening ribs are present on the bottom surface.