CA2354807A1 - Motor cooling fan blade assembly with finger guard - Google Patents
Motor cooling fan blade assembly with finger guard Download PDFInfo
- Publication number
- CA2354807A1 CA2354807A1 CA 2354807 CA2354807A CA2354807A1 CA 2354807 A1 CA2354807 A1 CA 2354807A1 CA 2354807 CA2354807 CA 2354807 CA 2354807 A CA2354807 A CA 2354807A CA 2354807 A1 CA2354807 A1 CA 2354807A1
- Authority
- CA
- Canada
- Prior art keywords
- fan
- finger guard
- guard ring
- fan blade
- blade assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
A prop fan blade assembly for a draft inducer motor cooling fan used in a high efficiency furnace includes rings concentric with and attached to an outer blade guard.
Cooling air is drawn through the concentric rings by the fan and blown onto the motor. The rings function as a finger guard while producing a confined airflow pattern which does not interfere with burner operation.
Cooling air is drawn through the concentric rings by the fan and blown onto the motor. The rings function as a finger guard while producing a confined airflow pattern which does not interfere with burner operation.
Description
r MOTOR COOLING FAN BLADE ASSEMBLY WITH FINGER GUARD
This invention relates to the field of motor cooling fans, and in particular, to a fan blade assembly for a motor cooling fan used in a furnace.
Hot air furnaces have become more efficient over the years. Certain improvements in heat exchangers, burner design, and combustion have increased the efficiency of furnaces, but these improvements frequently lead to the forced redesign of standard parts. One improvement that improves furnace efficiency is the addition of a draft inducer motor in the flue to create an induced draft. Such a motor needs to be cooled by a separate fan. The existing motor cooling fan for the draft inducer motor of a high efficiency furnace is deficient in that the fan throws air in a wider pattern than desired, sometimes interfering with proper burner operation. An integral finger guard in the form of a shroud in the existing motor, required for safety purposes, does not allow for controlling the discharge airflow pattern.
Briefly stated, a prop fan blade assembly for a draft inducer motor cooling fan used in a high efficiency furnace includes rings concentric with and attached to an outer blade guard. Cooling air is drawn through the concentric rings by the fan and blown onto the motor. The rings function as a finger guard while producing a confined airflow pattern which does not interfere with burner operation.
According to an embodiment of the invention, a fan blade assembly for a motor cooling fan includes a hub having a centered hole therein for attachment to a fan shaft a plurality of fan blades attached to the hub, an outermost edge of each of the plurality of fan blades describing a first diameter around the fan shaft as the fan shaft and plurality of fan blades rotate; an outer finger guard ring attached to the outermost edge of at least two of the plurality of fan blades, the outer finger guard ring having a circular shape; at least one circular-shaped inner finger guard ring concentrically arranged with the outer finger guard ring and attached to at least two of the plurality of fan blades; and the outer finger guard ring and the at least one inner finger guard ring being disposed such that air drawn by the fan passes between the at least one inner finger guard ring and the outer finger guard ring before it passes between the plurality of fan blades.
Fig. 1 shows a simplified schematic view of a draft inducer motor housing and its relation to a burner assembly in a gas fiirnace.
Fig. 2 shows a perspective view of the fan of the present invention.
Fig. 3 shows a top view of the fan of Fig. 2.
Fig. 4 shows a cross section view taken across the line 4-4 of Fig. 3.
Fig. 5 shows a second perspective view of the fan of the present invention.
Refernng to Fig. 1, in the prior art, a draft inducer motor 4 drives fan blades 6 producing an airflow pattern that cools draft inducer motor 4 as shown by arrows 8.
The air is blown partly toward a burner assembly 10. Burner assembly 10 includes a gas orifice 12 which provides natural gas or propane gas to a burner 14. The gas is ignited producing a flame 16. As is readily seen, air from fan blades 6 can interfere with flame 16.
Referring to Figs. 2-3, a prop fan blade assembly 20 includes a plurality of fan blades 22 attached to a hub 24. Hub 24 includes a central hole 18 to permit connection to a shaft of a fan motor (not shown). Fan blade assembly 20 fiuther includes an outer finger guard ring 26 preferably attached to the outer tip of each fan blade 22. In addition, a plurality of inner finger guard rings 28, concentric with outer finger guard ring 26, are also attached to each fan blade 22. Rings 28 can either be attached to or near a leading edge 34 of fan blades 22 or be attached to the entire width of each fan blade 22 as shown in Fig. 5.
An extension 30 of hub 24 extends past the point on hub 24 that fan blades 22 attach to. Extension 30 provides additional strength to hub 24 and limits the space through which a finger or other piece could be inserted and contact fan blades 22. The spacing between ring 26, rings 28, and hub extension 24 preferably meets UL
guidelines for protecting people from moving parts.
Referring to Fig. 4, the outer finger guard ring 26 and the inner finger guard rings 28 are disposed such that air drawn by fan blade assembly 20 passes between the finger guard rings 26, 28 before it passes between fan blades 22. In the preferred embodiment, rings 28 are on the side of fan blades 22 in the direction the air flow comes from (upstream), while ring 26 extends a distance beyond fan blades 22 in the direction downstream of the air flow, preferably so that a downstream edge 27 of ring 26 is even with a downstream end 25 of hub 24. Rings 26, 28 are optionally on both sides of fan blades 22.
The edges of rings 26, 28 in the upstream the air flow direction are in the same plane if the fan blades 22 are substantially perpendicular to the fan motor shaft, but if the fan blades 22 are angled or curved in the upstream direction as shown in Fig. 5, the heights of rings 28 are preferably the same, resulting in the upstream edges of ring 26 some of rings 28, and ring 30 being at different levels as measured from downstream end 25 of hub 24.
Referring also to Fig. 5, a plurality of notches 32 are in rings 28, extending from a trailing edge 35 of one fan blade 22 to the leading edge 34 of the next fan blade 22. Since the leading edges 34 are not in the same plane as the trailing edges 35 due to the angle of the fan blades 22 to the plane normal to the rotating fan shaft (not shown), the distance, as measured in the direction of the axis of the fan shaft, between the leading edge 34 and the trailing edge 35, measured at each ring, becomes the vertical distance of each notch 32. The horizontal distance of each notch is preferably equal to the distance between fan blades 22. In other words, since there is full contact between each ring 28 and each fan blade 22 along the width (in the direction of rotation) of the fan blade, each ring 28 is higher (in the axial direction of the fan shaft) at the trailing edge 35 than at the leading edge 34 of each fan blade 22. Each notch 32 in each ring 28 brings the lower edge (closer to the downstream end 25 of hub 24) of ring 28 from the level of trailing edge 35 of one fan blade 22 to the level of leading edge 34 of the next fan blade 22. The notches 32 as shown in the figures provides additional air flow not present if notches 32 are absent.
Although fan blade assembly 20 can be constructed by attaching its component pieces using an adhesive or welding/brazing, depending on whether the fan material is wood, plastic, or metal, in the preferred embodiment, fan blade assembly 20 is one-piece plastic, such as VALOX 310-SEO unreinforced PBT
polyester plastic.
This invention relates to the field of motor cooling fans, and in particular, to a fan blade assembly for a motor cooling fan used in a furnace.
Hot air furnaces have become more efficient over the years. Certain improvements in heat exchangers, burner design, and combustion have increased the efficiency of furnaces, but these improvements frequently lead to the forced redesign of standard parts. One improvement that improves furnace efficiency is the addition of a draft inducer motor in the flue to create an induced draft. Such a motor needs to be cooled by a separate fan. The existing motor cooling fan for the draft inducer motor of a high efficiency furnace is deficient in that the fan throws air in a wider pattern than desired, sometimes interfering with proper burner operation. An integral finger guard in the form of a shroud in the existing motor, required for safety purposes, does not allow for controlling the discharge airflow pattern.
Briefly stated, a prop fan blade assembly for a draft inducer motor cooling fan used in a high efficiency furnace includes rings concentric with and attached to an outer blade guard. Cooling air is drawn through the concentric rings by the fan and blown onto the motor. The rings function as a finger guard while producing a confined airflow pattern which does not interfere with burner operation.
According to an embodiment of the invention, a fan blade assembly for a motor cooling fan includes a hub having a centered hole therein for attachment to a fan shaft a plurality of fan blades attached to the hub, an outermost edge of each of the plurality of fan blades describing a first diameter around the fan shaft as the fan shaft and plurality of fan blades rotate; an outer finger guard ring attached to the outermost edge of at least two of the plurality of fan blades, the outer finger guard ring having a circular shape; at least one circular-shaped inner finger guard ring concentrically arranged with the outer finger guard ring and attached to at least two of the plurality of fan blades; and the outer finger guard ring and the at least one inner finger guard ring being disposed such that air drawn by the fan passes between the at least one inner finger guard ring and the outer finger guard ring before it passes between the plurality of fan blades.
Fig. 1 shows a simplified schematic view of a draft inducer motor housing and its relation to a burner assembly in a gas fiirnace.
Fig. 2 shows a perspective view of the fan of the present invention.
Fig. 3 shows a top view of the fan of Fig. 2.
Fig. 4 shows a cross section view taken across the line 4-4 of Fig. 3.
Fig. 5 shows a second perspective view of the fan of the present invention.
Refernng to Fig. 1, in the prior art, a draft inducer motor 4 drives fan blades 6 producing an airflow pattern that cools draft inducer motor 4 as shown by arrows 8.
The air is blown partly toward a burner assembly 10. Burner assembly 10 includes a gas orifice 12 which provides natural gas or propane gas to a burner 14. The gas is ignited producing a flame 16. As is readily seen, air from fan blades 6 can interfere with flame 16.
Referring to Figs. 2-3, a prop fan blade assembly 20 includes a plurality of fan blades 22 attached to a hub 24. Hub 24 includes a central hole 18 to permit connection to a shaft of a fan motor (not shown). Fan blade assembly 20 fiuther includes an outer finger guard ring 26 preferably attached to the outer tip of each fan blade 22. In addition, a plurality of inner finger guard rings 28, concentric with outer finger guard ring 26, are also attached to each fan blade 22. Rings 28 can either be attached to or near a leading edge 34 of fan blades 22 or be attached to the entire width of each fan blade 22 as shown in Fig. 5.
An extension 30 of hub 24 extends past the point on hub 24 that fan blades 22 attach to. Extension 30 provides additional strength to hub 24 and limits the space through which a finger or other piece could be inserted and contact fan blades 22. The spacing between ring 26, rings 28, and hub extension 24 preferably meets UL
guidelines for protecting people from moving parts.
Referring to Fig. 4, the outer finger guard ring 26 and the inner finger guard rings 28 are disposed such that air drawn by fan blade assembly 20 passes between the finger guard rings 26, 28 before it passes between fan blades 22. In the preferred embodiment, rings 28 are on the side of fan blades 22 in the direction the air flow comes from (upstream), while ring 26 extends a distance beyond fan blades 22 in the direction downstream of the air flow, preferably so that a downstream edge 27 of ring 26 is even with a downstream end 25 of hub 24. Rings 26, 28 are optionally on both sides of fan blades 22.
The edges of rings 26, 28 in the upstream the air flow direction are in the same plane if the fan blades 22 are substantially perpendicular to the fan motor shaft, but if the fan blades 22 are angled or curved in the upstream direction as shown in Fig. 5, the heights of rings 28 are preferably the same, resulting in the upstream edges of ring 26 some of rings 28, and ring 30 being at different levels as measured from downstream end 25 of hub 24.
Referring also to Fig. 5, a plurality of notches 32 are in rings 28, extending from a trailing edge 35 of one fan blade 22 to the leading edge 34 of the next fan blade 22. Since the leading edges 34 are not in the same plane as the trailing edges 35 due to the angle of the fan blades 22 to the plane normal to the rotating fan shaft (not shown), the distance, as measured in the direction of the axis of the fan shaft, between the leading edge 34 and the trailing edge 35, measured at each ring, becomes the vertical distance of each notch 32. The horizontal distance of each notch is preferably equal to the distance between fan blades 22. In other words, since there is full contact between each ring 28 and each fan blade 22 along the width (in the direction of rotation) of the fan blade, each ring 28 is higher (in the axial direction of the fan shaft) at the trailing edge 35 than at the leading edge 34 of each fan blade 22. Each notch 32 in each ring 28 brings the lower edge (closer to the downstream end 25 of hub 24) of ring 28 from the level of trailing edge 35 of one fan blade 22 to the level of leading edge 34 of the next fan blade 22. The notches 32 as shown in the figures provides additional air flow not present if notches 32 are absent.
Although fan blade assembly 20 can be constructed by attaching its component pieces using an adhesive or welding/brazing, depending on whether the fan material is wood, plastic, or metal, in the preferred embodiment, fan blade assembly 20 is one-piece plastic, such as VALOX 310-SEO unreinforced PBT
polyester plastic.
Claims (8)
1. A prop fan blade assembly for a motor cooling fan, characterized by:
a hub having a centered hole therein for attachment to a fan shaft;
a plurality of fan blades attached to said hub, an outermost edge of each of said plurality of fan blades describing a first diameter around said fan shaft as said fan shaft and plurality of fan blades rotate;
an outer finger guard ring attached to said outermost edge of at least two of said plurality of fan blades, said outer finger guard ring having a circular shape;
at least one circular-shaped inner finger guard ring concentrically arranged with said outer finger guard ring and attached to at least two of said plurality of fan blades; and said outer finger guard ring and said at least one inner finger guard ring being disposed such that air drawn by said fan passes between said at least one inner finger guard ring and said outer finger guard ring before it passes between said plurality of fan blades.
a hub having a centered hole therein for attachment to a fan shaft;
a plurality of fan blades attached to said hub, an outermost edge of each of said plurality of fan blades describing a first diameter around said fan shaft as said fan shaft and plurality of fan blades rotate;
an outer finger guard ring attached to said outermost edge of at least two of said plurality of fan blades, said outer finger guard ring having a circular shape;
at least one circular-shaped inner finger guard ring concentrically arranged with said outer finger guard ring and attached to at least two of said plurality of fan blades; and said outer finger guard ring and said at least one inner finger guard ring being disposed such that air drawn by said fan passes between said at least one inner finger guard ring and said outer finger guard ring before it passes between said plurality of fan blades.
2. A prop fan blade assembly according to claim 1 wherein an edge of said at least one inner finger guard ring is coplanar with an edge of said outer finger guard ring.
3. A prop fan blade assembly according to claim 1, wherein said fan blade assembly is one-piece.
4. A prop fan blade assembly according to claim 3, wherein said fan blade assembly is plastic.
5. A prop fan blade assembly according to claim 1, wherein said at least one inner finger guard ring includes a notched portion in between each of said fan blades.
6. A prop fan blade assembly according to claim 1, wherein said at least one inner finger guard ring is attached to each of said plurality of fan blades across an entire width of each fan blade.
7. A prop fan blade assembly according to claim 1, wherein said at least one inner finger guard ring is attached to each of said plurality of fan blades at a leading edge of each fan blade.
8. A prop fan blade assembly according to claim 1, wherein said at least one inner finger guard ring extends above and below said plurality of fan blades.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US65274500A | 2000-08-31 | 2000-08-31 | |
| US09/652,745 | 2000-08-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2354807A1 true CA2354807A1 (en) | 2002-02-28 |
Family
ID=24617984
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2354807 Abandoned CA2354807A1 (en) | 2000-08-31 | 2001-08-07 | Motor cooling fan blade assembly with finger guard |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU751254B2 (en) |
| CA (1) | CA2354807A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105587760A (en) * | 2016-01-15 | 2016-05-18 | 江苏大学 | Rolling bearing with blades for enhanced heat dissipation, and design method thereof |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4318693A (en) * | 1980-11-20 | 1982-03-09 | Robinson Industries, Inc. | Axial fan turning diffuser |
| NL9402191A (en) * | 1994-12-22 | 1996-08-01 | Helpman Intellectual Propertie | Fan. |
| NL9402187A (en) * | 1994-12-22 | 1996-08-01 | Helpman Intellectual Propertie | Household fan. |
-
2001
- 2001-08-07 CA CA 2354807 patent/CA2354807A1/en not_active Abandoned
- 2001-08-30 AU AU65556/01A patent/AU751254B2/en not_active Ceased
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105587760A (en) * | 2016-01-15 | 2016-05-18 | 江苏大学 | Rolling bearing with blades for enhanced heat dissipation, and design method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6555601A (en) | 2002-03-07 |
| AU751254B2 (en) | 2002-08-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |