Multi-blade fan for air-cooled engine

• US 20060275123A1
• Filed: 06/01/2006
• Published: 12/07/2006
• Est. Priority Date: 06/02/2005
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Tabata, Yutaka, Hatsugai, Tsutomu, Ideguchi, Takahiro
• Granted Patent: US 7,618,239 B2
• Time in Patent Office: Days
• US Class Current: 416/189
• CPC Class Codes: F04D 29/281 for fans or blowers
• CPC Class Codes: F04D 29/666 by means of rotor construction or layout, e.g. unequal distribution of blades or vanes

Abstract

In a multi-blade fan for an air-cooled engine, by defining the inlet angle β1 and the angle β′2 to make the sum thereof less than 80° (preferably defining β1 as 32° and β′2 as 36°), the multi-blade fan achieves greater air volume than in the case where the sum is made 80° or greater, where β1 is the angle between the relative velocity direction and the peripheral direction on the inlet side of the blades, β2 is the angle between the relative velocity direction and the peripheral direction on the outlet side of the blades, and β′2 is the difference obtained by subtracting β2 from 180°. The number of blades can therefore be reduced to realize lower noise level while still maintaining the same air volume as the prior art multi-blade fan.

Claims

1. A multi-blade fan having an impeller equipped with a plurality of blades attached to an air-cooled internal combustion engine to be rotated to blow air toward the engine to cool, comprising:

an inlet angle β

1 defined to be an angle between a relative velocity direction and a peripheral direction on an inlet side of the blades,

an outlet angle β

2 defined to be an angle between the relative velocity direction and the peripheral direction on an outlet side of the blades; and

an angle β

′

2 defined to be a difference obtained by subtracting the outlet angle β

2 from 180°

,

wherein a sum of the inlet angle β

1 and the angle β

′

2 is made less than 80°

.

2. The multi-blade fan according to claim 1, wherein the inlet angle β

1 is 32° and

the difference angle β

′

2 is 36°

, such that the sum is made 68°

.

3. The multi-blade fan according to claim 1, wherein an angle θ

1 is given a value that is between 40% and 50% of an angle θ

0, where the angle θ

0 is an angle between L1 and L2;

the angle θ

1 is angle between L1 and L3;

L1 is a straight line obtained by connecting the inlet side of the blades with a center of rotation of the impeller;

L2 is a straight line obtained by connecting an intersection of a circumference of the outlet side of the blades and the direction of the inlet side relative velocity with the center of rotation of the impeller; and

L3 is a straight line obtained by connecting the outlet side of the blades with the center of rotation of the impeller.

4. The multi-blade fan according to claim 3, wherein the angle θ

1 is given a value that is 48% of the angle θ

0.

5. The multi-blade fan according to claim 1, wherein number of blades (Z) is determined in accordance with an equation expressed by

Z={2π

sin (inlet angle β

1+angle 90°

−

angle β

′

2)/2)}/{constant term K×

2.3 log10 (impeller outer diameter D2/impeller inner diameter D1)}.

6. The multi-blade fan according to claim 5, wherein the constant term K is given a value between 0.5 and 0.68.

7. The multi-blade fan according to claim 6, wherein the constant term K is given a value 0.5.

8. The multi-blade fan according to claim 1, further including:

a cover enclosing the impeller;

an air intake port formed in the cover; and

an annular roof formed continuously along the blades and configured so that at a space between each set of adjacent blades it covers a part constituted by a surface facing the air intake port over a width a extending from the outlet side in the direction of the inlet side,

wherein the width a is defined between 55% and 75% of a quotient obtained by dividing b by 2, where D2 is an outer diameter of the impeller, D3 is a diameter of the intake port and b is the difference obtained by subtracting diameter D3 from the outer diameter D2.

9. The multi-blade fan according to claim 8, wherein the width a is defined 64% of the quotient obtained by dividing b by 2.