Centrifugal multiblade blower

• US 20020025253A1
• Filed: 08/03/2001
• Published: 02/28/2002
• Est. Priority Date: 08/04/2000
• Status: Active Grant

• Current Assignee: Calsonic Kansei Corporation
• Original Assignee: Calsonic Kansei Corporation
• Inventors: Yajima, Toshio, Ozeki, Yukio, Onda, Masaharu
• Granted Patent: US 6,604,906 B2
• Time in Patent Office: Days
• US Class Current: 415/206
• CPC Class Codes: F04D 25/082 the unit having provision for cooling the motor
• CPC Class Codes: F04D 29/162 of a centrifugal flow wheel
• CPC Class Codes: F04D 29/4233 with volutes extending mainly in axial or radially inward direction
• CPC Class Codes: F04D 29/5806 Cooling the drive system

Abstract

A centrifugal multiblade blower includes a first counter-flow prevention means that prevents part of air flowing through a scroll chamber from flowing through a first aperture defined between a multiblade fan and a suction-side case plate of a scroll casing back to a suction port, and a second counter-flow prevention means that prevents part of air flowing through the scroll chamber from flowing through a second aperture defined between the multiblade fan and a motor-side case plate of the scroll casing back to the upstream side of the scroll chamber. A length L1 of the scroll chamber measured in the motor-shaft axial direction is dimensioned to be longer than a length L2 of the multiblade fan measured in the motor-shaft axial direction. Additionally the scroll chamber is gradually enlarged toward a discharge port of the casing.

Claims

1. A centrifugal multiblade blower comprising:

a multiblade fan (2) having a plurality of blades (2a);

a fan motor (3) having a motor shaft (3a) on which the multiblade fan (2) is mounted;

a scroll casing (4) that accommodates therein the multiblade fan (2) and has a discharge port (4c) and cooperates with an outer periphery of the multiblade fan (2) to define a spiral scroll chamber (4a);

the casing comprising;

(i) a suction-side case plate (4d) having a suction port (4b); and

(ii) a motor-side case plate (4e) which is located opposite to the suction-side case plate (4d) in such a manner as to sandwich the multiblade fan (2) between the suction-side case plate (4d) and the motor-side case plate (4e), and on which a motor body (3b) of the fan motor (3) is mounted;

a first counter-flow prevention means (10) for preventing part of air flowing through the scroll chamber (4a) from flowing through a first aperture (G1) defined between the multiblade fan (2) and the suction-side case plate (4d) back to the suction port (4b); and

a second counter-flow prevention means (20) for preventing part of air flowing through the scroll chamber (4a) from flowing through a second aperture (G2) defined between the multiblade fan (2) and the motor-side case plate (4e) back to an upstream side of the scroll chamber (4a);

wherein a length (L1) of the scroll chamber (4a) measured in an axial direction of the motor shaft (3a) is dimensioned to be longer than a length (L2) of the multiblade fan (2) measured in the axial direction of the motor shaft (3a), and the scroll chamber (4a) is gradually enlarged toward the discharge port (4c) of the casing (4).

2. The centrifugal multiblade blower as claimed in claim 1, wherein the scroll chamber (4a) is gradually enlarged in the axial direction of the motor shaft (3a) at an axial enlargement angle (α

) representative of a magnitude of enlargement of the scroll chamber (4a) in the axial direction of the motor shaft (3a) toward the discharge port (4c), and additionally the scroll chamber (4a) is gradually enlarged in a radial direction of the multiblade fan (2) at a radial enlargement angle (n) representative of a magnitude of enlargement of the scroll chamber (4a) in the radial direction of the multiblade fan (2) from a tongue portion (4k) of the scroll casing (4) toward the discharge port (4c), the radial enlargement angle (n) being defined by an expression R=R₀exp{n(θ

+θ

₀)}, where R denotes a radius of the scroll casing (4), R₀ denotes a radius of the multiblade fan (2), θ

denotes an angle measured in a direction of rotation of the multiblade fan (2) from a central point (P) of the tongue portion (4k) that defines a narrowest portion of the scroll chamber (4a), and θ

₀ denotes an angle from a point (Q) across which the length (L1) of the scroll chamber (4a) measured in the axial direction of the motor shaft (3a) begins to enlarge to the central point (P) of the tongue portion (4k).

3. The centrifugal multiblade blower as claimed in claim 2, wherein the axial enlargement angle (α

) of the scroll chamber (4a) is set at substantially 6 degrees.

4. The centrifugal multiblade blower as claimed in claim 3, wherein the radial enlargement angle (n) of the scroll chamber (4a) is set at substantially 3.3 degrees.

5. The centrifugal multiblade blower as claimed in claim 4, wherein the scroll chamber (4a) is gradually uniformly enlarged in opposite axial directions of the motor shaft (3a) at the axial enlargement angle (α

) of substantially 6 degrees from the tongue portion (4k) toward the discharge port (4c).

6. The centrifugal multiblade blower as claimed in claim 1, wherein:

the first counter-flow prevention means (10) comprises;

(i) a first fan rib (11) provided on the multiblade fan (2) so that the first fan rib (11) is protruded from the multiblade fan (2) to the first aperture (G1), and coaxially arranged with respect to an axis of the multiblade fan (2) and extending completely in a circumferential direction of the multiblade fan (2) around an entire circumference of an outer peripheral curved surface portion normal to and adjacent to a perimeter of a top of the multiblade fan (2) facing a front end of the motor shaft (3a); and

(ii) a first case rib (12) provided on the suction-side case plate (4d) so that the first case rib (12) is protruded from the suction-side case plate (4d) to the first aperture (G1), and coaxially arranged with and radially spaced apart from the first fan rib (11), and extending completely in the circumferential direction of the multiblade fan (2) so that the first fan rib (11) and the first case rib (12) are located close to each other and radially spaced from each other by a predetermined distance; and

the second counter-flow prevention means (20) comprises;

(i) a second fan rib (21) provided on the multiblade fan (2) so that the second fan rib is protruded from the multiblade fan (2) to the second aperture (G2), and coaxially arranged with respect to the axis of the multiblade fan (2) and extending completely in the circumferential direction of the multiblade fan (2) around an entire circumference of an outer peripheral portion of a base of the multiblade fan (2) facing a rear end of the motor shaft (3a); and

(ii) a second case rib (22) provided on the motor-side case plate (4e) so that the second case rib (22) is protruded from the motor-side case plate (4e) to the second aperture (G2), and coaxially arranged with and radially spaced apart from the second fan rib (21), and extending completely in the circumferential direction of the multiblade fan (2) so that the second fan rib (21) and the second case rib (22) are located close to and radially spaced from each other by a predetermined distance.

7. The centrifugal multiblade blower as claimed in claim 6, wherein the first fan rib (11) is formed as a cylindrical fan rib having an I shape in cross section, and the first case rib (12) is formed as an inverted U shaped first case rib that covers the first fan rib (11) and has a pair of radially opposing, inner and outer rib wall portions between which the first fan rib (11) is located in close proximity to each of the radially opposing, inner and outer rib wall portions.

8. The centrifugal multiblade blower as claimed in claim 6, wherein the first fan rib (11) is formed as a rimmed annular fan rib having a L shape in cross section and coaxially arranged with respect to the axis of the multiblade fan (2) and extending completely in the circumferential direction of the multiblade fan (2) around the entire circumference of the perimeter of the top of the multiblade fan (2), and the first case rib (12) comprises:

(i) a first rib portion (12a) formed as an inverted U shaped case rib portion that covers the rimmed annular fan rib with a predetermined clearance, and coaxially located close to the first fan rib (11) so that the first rib portion (12a) and the first fan rib (11) are radially spaced from each other by a predetermined distance on both sides of the rimmed annular fan rib;

(ii) a second rib portion (12b) formed as a radially-extending annular flat-faced rib portion formed integral with the suction-side case plate (4d) and extending radially outwards from an outer periphery of the inverted U shaped case rib portion and located parallel to and close to the perimeter of the top of the multiblade fan (2) by a predetermined distance;

(iii) a third rib portion (12c) formed as a substantially cylindrical rib portion formed integral with the suction-side case plate (4d) and extending perpendicular to the radially-extending annular flat-faced rib portion and located adjacent to the circumference of the outer peripheral curved surface portion normal to and adjacent to the perimeter of the top of the multiblade fan (2) by a predetermined distance.

9. The centrifugal multiblade blower as claimed in claim 6, which further comprises:

a motor protective case (3c) that protects the motor body (3b);

a communication portion (6) that intercommunicates an interior space of the motor body (3b) and a high-pressure area of the scroll chamber having a comparatively high pressure; and

a cut-out portion (23) formed in the second case rib (22) and exposed to a low-pressure area of the scroll chamber having a lower pressure than the pressure in the high-pressure area to intercommunicate the low-pressure area of the scroll chamber and a space (S) which is defined between the motor-side case plate (4e) and the multiblade fan (2) and into which a portion of the motor body (3b) is exposed; and

wherein a portion of the motor protective case (3c) exposed into the space (S) has at least one communication hole (3d) through which the interior space of the motor body (3b) and the space (S) are communicated with each other.