WO2002075159A1

WO2002075159A1 - Axial fan

Info

Publication number: WO2002075159A1
Application number: PCT/TR2001/000012
Authority: WO
Inventors: Ahmet Fatih AÇIKGÖZ
Original assignee: Arçelik A.S.
Priority date: 2001-03-15
Filing date: 2001-03-15
Publication date: 2002-09-26
Also published as: TR200301280T1

Abstract

The present invention is related to an axial fan for air circulation of a household applicance, especially a refrigerator while providing a powerful cooled air blowing into the body with fewer amounts of energy and high efficiency.

Description

AXIAL FAN

The present invention is related to an axial fan for circulating air inside a household appliance, especially a refrigerator.

In refrigerators, especially axial fans are used for blowing the cooled air into the body. While blowing efficiently for cooling, sound effects must be reduced as much as possible. For this purpose curved blade shapes are preferred.

In GB2302141, an axial flow fan for a microwave oven capable of effectively cooling a magnetron and a high voltage transformer of the same and effectively circulating air inside, so that an improved microwave oven having a higher efficiency and a lower noise can be achieved, includes five blades spaced-apart at regular intervals and placed at the outer circumferential surface of a cylindrical hub. The blades have a ratio "fan hub diameter/fan outer diameter" in the range of 0.28 - 0.35. Preferred blade pitch and sweep angle ranges, and dimensions are also disclosed.

The object of the present invention is to design an axial fan which can be easily manufactured, and capable of blowing the air with less torque and low power consumption.

An embodiment of an axial fan, which is realised in order to attain the said object of the invention is illustrated in the attached drawings, wherein;

Figure 1, is the three dimensional back view of the axial fan

Figure 2, is the three dimensional front view of the axial fan Figure 3 a, is the three dimensional side view of the axial fan

Figure 3 b, is another three dimensional side view of the axial fan

Figure 4, is the front view of the axial fan

Figure 5 a, is the schematic view of the inlet angle and exit angle at the tip

Figure 5b, is the schematic view of the inlet angle and exit angle at the blade center Figure 5 c, is the schematic view of the inlet angle and exit angle at the hub

Figure 6a, Pressure versus flow rate graph

Figure 6b, Efficiency versus flow rate graph

Figure 7a, θ versus MN graph at the tip

Figure 7b, β versus MN graph at the tip

Figure 8a, θ versus MN graph at the center

Figure 8b, β versus MN graph at the center

Figure 9a, θ versus MN at the hub

Figure 9b, β versus MN graph at the hub

The components shown in the drawings have the following numbers;

1. Fan

2. Blade 3. Blade thickness

4. Blade trailing edge

5. Blade leading edge

6. Hub

7. Tip 8. Blade center

9. Root

10. Curvature

11. Inlet angle

12. Exit angle 13. Upper surface

14. Lower surface

15. Fan outer diameter

16. Fan inner diameter

The axial fan (1) of the current invention has a hub (6) with a cylindrical shape and four blades (2) connected to the hub (6). All four blades have the same shapes and are placed at equal angles with respect to each other. The connecting part where one side of the blade (2) is connected to the hub (6) is called as root (9). The other end of the blade (2) is named as tip (7), and middle part of the blade (2) is called as blade center (8). The hub (6) diameter is named as fan inner diameter (16), and twice the distance between the tip (7) and hub center equals to fan outer diameter (15). The edge of the blade (2) which connects the tip (7) and the root (9) and faces the air first, is called as blade leading edge (5) and the other edge of the blade (2) which connects the tip (7) and the root (9) and faces the air after leading edge while moving, is called as blade trailing edge (4). The blades (2) have an upper surface (13) and a lower surface (14). The upper and lower surfaces (13,14) have curved shape. The blade sections are all taken along cylinders that have their center coinciding with the center of the hub (6). Curvature (10) of the axial fan (1) is the plane that is formed by the mid points of the lines connecting the upper surface (13) and lower surface (14) at any blade section. The angle between the hub (6) centerline and the tangent of the curvature (10) at blade leading edge (5) is the inlet angle (11). The angle between the hub (6) centerline and the tangent of the curvature at blade trailing edge (4) is the exit angle (12). The distance between the upper and lower surfaces (13,14) is the blade thickness (3). The blade (2) has a uniform blade thickness (3).

In the preferred embodiment, the curvature (10), the inlet angle (11) and the exit angle (12) of the blade (2) are the same at all blade sections and there is a constant blade thickness (3), preferably 1 mm between upper and lower surfaces (13,14) in any blade section (3). The curvature (10) of the blade (2) can be defined with a third order polynomial;

θ = 503 (MN) ³ - 601 (MN) ² + 300 MN

M is the distance along meridional curve and is equal to (Σ (δ M)),R is the radius, MN is the radius normalized distance along meridional curve and is equal to (Σ (δM/ δR) ), (θ ) is the blade angle which is the rotation around Z axis from X to Y axis according to Right Hand Rule, (β) is the blade angle which is equal to ( atan (Θ/MN )).

The important parameters for axial fans are fan efficiency (EF), fan pressure head (P), fan flow rate (Q), and angular velocity (w). The fan efficiency (EF) is the ratio of the work done by the axial fan (1) per power supplied for axial fan (1), the pressure head (P) is the pressure difference between the entrance and exit of the axial fan (1), the flow rate (Q) is the gas flow per unit time and angular velocity (w) is the turning velocity of the axial fan (1) the number of revolutions per unit time.

Due to its high efficiency, the axial flow fan (1) requires less torque and decreases the power consumption.

The axial fan (1) can work within an angular velocity (w) of 2200 - 2600 rpm and, have an inner diameter (16) between 25 - 35 mm, an outer diameter (17) between 80 - 120 mm, an inlet angle (11) of (38 +/- 3) deg, and fan exit angle (12) of (80 +/- 3) deg.

In the preferred embodiment inner diameter (16) is 30 mm, outer diameter (17) is 100 mm, fan efficiency is %30, inlet angle (11) is 80 deg, and fan exit angle (12) is 38 deg. The ratio of the inner diameter (16) to outer diameter (17) or simply hub to tip ratio is 0.3.

In the preferred embodiment the front face of the hub (6) is a flat surface. It can have a curved form also.

The axial fan (1) of the current invention can be used in refrigerators, for circulating the air inside the refrigerator. Since the axial fan (1) is highly efficient energy consumption of the refrigerator will decrease.

Claims

- An axial fan (1) for household appliances especially for a refrigerator, comprising, a hub (6), four blades (2) which have the same shape and are spaced apart with a regular interval around the hub (6), where the blade (2) has a root (9), a tip (7), a trailing edge (4), a leading edge (5), an upper surface

(13), a lower surface (14), an inlet angle (11) which is the angle between the hub (6) centerline and the tangent of the curvature at blade leading edge (5), and an exit angle (12) which is the angle between the hub (6) centerline and the tangent of the curvature at blade trailing edge (4), characterized in that the curvature (10), the inlet angle (11) and the exit angle (12) of the blade (2) are the same at all blade sections, and blade (2) has a constant blade thickness (3) between upper and lower surfaces (13,14) in any blade section.

- An axial fan according to claim 1, characterized by a ratio of 0.3 between the inner diameter (16) which is equal to hub (6) diameter, and outer diameter (17) which is twice the distance between the hub (6) center and the tip (7)

- An axial fan according to claims 1 and 2, characterized by inlet angle (11) of (80+/- 3) (deg), and an exit angle (12) of (38 +/- 3 deg).

- An axial fan according to claims 1 to 3, characterized by an inner diameter (16) of (30+/- 5) (mm), and an outer diameter (17) of (100+/- 10 mm).

- An axial fan according to claims 1 to 4, characterized by an angular velocity of (2400+/- 200 rpm).

- An axial fan according to claims 1 to 5, characterized by a curvature (10) which is the curve formed by the mid points of the lines connecting the upper surface (13) and lower surface (14), with a third order polynomial; θ= 503(MN)³-601(MN)² + 300MN

where due to blade general definitions, M is the distance along meridional curve and is equal to ((Σ (δ M)),R is the radius, MN is the radius normalized distance along meridional curve and is equal to (Σ (δM/ δR)), (θ ) is the blade angle which is the rotation around Z axis from X to Y axis according to Right Hand Rule.

- An axial fan according to claims 1 to 6, characterized by a blade thickness (3) of(1.0to3.0mm).

- An axial fan according to claims 1 to 7, characterized by the hub (6) with a semi-spherical front face.