Multiblade radial fan and method for making same

• US 5,741,118 A
• Filed: 12/27/1995
• Issued: 04/21/1998
• Est. Priority Date: 04/28/1994
• Status: Expired due to Term

• Current Assignee: Toto Limited
• Original Assignee: Toto Limited
• Inventors: Hatakeyama, Makoto, Shinbara, Noboru
• Primary Examiner(s): Denion, Thomas E.
• Application Number:
  US08/578,513
• Time in Patent Office: 846 Days
• Field of Search: 416/185, 416/186 R, 416/223 B, 416/238, 416/DIG. 2, 416/187
• US Class Current: 416/186.00R
• CPC Class Codes: F04D 29/283 rotors of the squirrel-cage type

Abstract

Noise is minimized in the design of multiblade radial fans, wherein the specifications of the impeller of a multiblade radial fan are determined so as to satisfy the correlation expressed by the formula ν≧-0.857Z₁ +1.009 (in the preceding formula, ν=r₀ /r₁, Z₁ =(r₁ -r₀)/ r₁ -nt/(2π), where r₀ is the inside radius of the impeller, r₁ is the outside radius of the impeller, n is the number of radially-directed blades, and t is the thickness of the radially-directed blades).

Claims

1. A multiblade radial fan comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially-directed blades, each blade having a thickness t, wherein the impeller satisfies the formula:

space="preserve" listing-type="equation">ν

≧

-0.857Z.sub.1 +1.009,

wherein ν

=r₀ /r₁, and Z₁ =(r₁ -r₀)/ r₁ -nt/(2π

)!.

2. A multiblade radial fan according to claim 1, wherein each radially-directed blade has an inner end portion, and a plurality of the inner end potions are bent in a direction of rotation of the impeller.

3. A multiblade radial fan comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially-directed blades, each blade having a thickness t, wherein the impeller satisfies the formulas:

space="preserve" listing-type="equation">ν

≧

-0.857Z.sub.1 +1.009

and

space="preserve" listing-type="equation">0.8≧

ν

≧

0.4,

wherein ν

=r₀ /r₁, and

Z₁ =(r₁ -r₀)/ r₁ -nt/(2π

)!.

4. A multiblade radial fan according to claim 3, wherein each radially-directed blade has an inner end portion, and a plurality of the inner end potions are bent in a direction of rotation of the impeller.

5. A multiblade radial fan comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially-directed blades, each blade having a thickness t, wherein the fan satisfies the formula:

space="preserve" listing-type="equation">(1.009-ν

)/(1-ν

)≦

Z.sub.2,

wherein ν

=r₀ /r₁,

Z₂ =0.857{t₀ / (2π

r₁ /n)-t!+1}, and

t₀ is a reference thickness=0.5 mm).

6. A multiblade radial fan according to claim 5, wherein each radially-directed blade has an inner end portion, and a plurality of the inner end potions are bent in a direction of rotation of the impeller.

7. A multiblade radial fan comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially-directed blades, each blade having a thickness t, wherein the impeller satisfies the formulas:

space="preserve" listing-type="equation">(1.009-ν

)/(1-ν

)≦

Z.sub.2

and

space="preserve" listing-type="equation">0.8≧

ν

≧

0.4,

wherein ν

=r₀ /r₁,

Z₂ =0.857{t₀ / (2π

r₁ /n)-t!+1}, and

t₀ is a reference thickness=0.5 mm).

8. A multiblade radial fan according to claim 7, wherein each radially-directed blade has an inner end portion, and a plurality of the inner end potions are bent in a direction of rotation of the impeller.

9. A method for making a multiblade radial fan, comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially-directed blades, each blade having a thickness t, the methods comprising the steps of:

specifying the impeller so as to satisfy a formula;

space="preserve" listing-type="equation">ν

≧

-0.857Z.sub.1 +1.009,

wherein ν

=r₀ /r₁, Z₁ =(r₁ -r₀)/ r₁ -nt/(2π

)!; and

making a fan comprising the specified impeller.

10. A method for making a multiblade radial fan comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially-directed blades, each blade having a thickness t, the method comprising the steps of;

specifying the impeller so as to satisfy the formulas;

space="preserve" listing-type="equation">ν

≧

-0.857Z.sub.1 +1.009

and

space="preserve" listing-type="equation">0.8≧

ν

≧

0.4,

wherein ν

=r₀ /r₁, Z₁ =(r₁ -r₀)/ r₁ -nt/(2π

)!; and

making a fan comprising the specified impeller.

11. A method for making a multiblade radial fan comprising an impeller having an inside radius r₀ and an outside radius r₁, and a number n of radially directed blades, each blade having a thickness t, the method comprising the steps of;

specifying the impeller so as to satisfy the formula;

space="preserve" listing-type="equation">(1.009-ν

)/(1-ν

)≦

Z.sub.2,

wherein ν

=r₀ /r₁,

Z₂ =0.857{t₀ / (2π

r₁ /n)-t!+1}, and

t₀ is a reference thickness=0.5 mm); and

making a fan comprising the specified impeller.

12. A method for making a multiblade radial fan, comprising an impeller having an inside radius r₀ and an outside radius r₁, a number n of radially-directed blades, each blade having a thickness t, the method comprising the steps of;

specifying the impeller of multiblade radial so as to satisfy the formula;

space="preserve" listing-type="equation">(1.009-ν

)/(1-ν

)≦

Z.sub.2

and

space="preserve" listing-type="equation">0.8≧

ν

≧

0.4,

wherein ν

=r₀ /r₁,

Z₂ =0.857{t₀ / (2π

r₁ /n)-t!+1}, and

t₀ is a reference thickness=0.5 mm); and

making a fan comprising the specified impeller.