Axial-flow type fan having an air inlet blade structure tipped with leading corners

Abstract

An axial-flow type fan includes a fan housing consisting of an air-boosting inlet, an air outlet and an air channel, and a fan wheel consisting of a hub and fan blades arranged about a rotary axis of the hub. Each of the fan blades has a tipped leading corner to constitute an air inlet blade structure which forms a topmost portion in a longitudinal direction and a forefront portion in a rotational direction. The tipped leading corners are situated in the air-boosting inlet of the fan housing while the air channel accommodates the fan wheel. When the fan wheel is rotated, the tipped leading corners of the fan blades are able to eliminate air turbulence and air noise in the air-boosting inlet of the fan housing.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an axial-flow type fan having an air inlet blade structure tipped with leading corners. More particularly, the present invention relates to an axial-flow type fan having an air inlet blade structure tipped with leading corners situated in an air-boosting inlet of a fan housing, thereby reducing air-shearing noise in operation.

2. Description of the Related Art

Referring initially to FIG. 1, it illustrates a conventional fan housing structure having an air outlet connecting with an air inlet. The construction of the conventional fan structure is disclosed in U.S. Pat. Nos. 4,734,015, 4,743,173, Re34,456, 4,806,081, 4,992,029, 5,028,216, 5,135,363 and 5,267,842 etc. The fan structure consists of a fan housing 10 and a fan wheel (so-called impeller) 20 accommodating therein. The construction of the fan housing 10 is shaped square including an air inlet side (so-called upstream side) 11 and an air outlet side (so-called downstream side) 11′ disposed at its either side. The air inlet forms an air-boosting inlet 12 while the air outlet (not labeled) forming an air-expanding outlet. An air channel 13 connects between the air-boosting inlet 12 and the air-expanding outlet. The fan wheel 20 is accommodated in the air channel 13, and consists of a hub 21 and a plurality of fan blades 22 arranged about a rotary axis of the hub 21. The construction of the hub 21 is a barrel-shaped object having an outer circumference on which equi-spaced and titled the fan blades 22 each of which forms a flat vane. In operation, when the fan wheel 20 is rotated, the fan blades 22 drives air to suck into the fan, housing 10 through the air-boosting inlet 12 that increases the pressure of air inlet. Subsequently, airflow may pass through the air channel 13 and exhaust from the air-expanding outlet that steadies an exhausting airflow.

However, there exist several drawbacks of the axial-flow type fan in use. Each flat vane of the fan blade 22 forms an inlet corner portion 221 as well as a flat portion at its endmost corner. The inlet corner portion 221 of the fan blade 22 is situated in the longitudinal section of the air-boosting inlet 12 and almost perpendicular to a surface of the air-boosting outlet 12. When the fan blades 22 drive a mass of the inlet air entering through the air-boosting inlet 12, the mass of the inlet air may impact the annular surface of the air-boosting inlet 12 that guides the inlet air for entering into the fan housing 10. In the radial section of the air-boosting inlet 12, the flat vane portion of the inlet corner portion 221 extends a straight leading edge 220 proximate the air inlet side. Also, when the fan blades 22 is rotated, the straight leading edge 220 aggravates the air turbulence generated on the annular surface of the air-boosting inlet 12 and causes air-shearing noise. Hence, there is a need for an inlet corner portion of the fan blade for improving air-shearing noise.

The present invention intends to provide an axial-flow type fan having an air inlet blade structure tipped with leading corners situated in an air-boosting inlet of a fan housing. When the fan is rotated, the leading corners are able to increase air pressure and to reduce air-shearing noise in the air-boosting inlet of the fan housing in such a way to mitigate and overcome the above problem.

SUMMARY OF THE INVENTION

The primary objective of this invention is to provide an axial-flow type fan having an air inlet blade structure tipped with leading corners, each of which forming a topmost blade portion in a longitudinal direction, which is situated in an air-boosting inlet of a fan housing, thereby the leading corners reducing air noise.

The secondary objective of this invention is to provide the axial-flow type fan having the air inlet blade structure tipped with leading corners, each of which forming a forefront portion in a rotational direction, which is situated in an air-boosting inlet of a fan housing, thereby the leading corners reducing air noise.

The third objective of this invention is to provide the axial-flow type fan having the air inlet blade structure tipped with leading corners radially approaching an annular surface of the air-boosting inlet and situated in an air-boosting inlet of a fan housing, thereby the leading corners reducing air noise.

The fourth objective of this invention is to provide the axial-flow type fan having the air inlet blade structure tipped with leading corners, each of which including a ridge on a leeward side connecting between an inlet leading corner point and an outlet trailing bottom point to thereby guide airflow.

The axial-flow type fan in accordance with the present invention includes a fan housing consisting of an air-boosting inlet, an air outlet and an air channel, and a fan wheel consisting of a hub and fan blades arranged about a rotary axis of the hub. Each of the fan blades has a tipped leading corner to constitute an air inlet blade structure which forms a topmost portion in a longitudinal direction and a forefront portion in a rotational direction. The tipped leading corners are situated in the air-boosting inlet of the fan housing while the air channel accommodates the fan wheel. When the fan wheel is rotated, the tipped leading corners of the fan blades are able to eliminate air turbulence and air noise in the air-boosting inlet of the fan housing.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in detail with reference to the accompanying drawings wherein:

FIG. 1 is a cutaway cross-sectional view of a conventional fan housing structure in accordance with the prior art;

FIG. 2 is an exploded perspective view of an axial-flow type fan having an air inlet blade structure tipped with leading corners in accordance with a preferred embodiment of the present invention;

FIG. 3 is a top plan view of the axial-flow type fan having the air inlet blade structure tipped with leading corners in accordance with the preferred embodiment of the present invention;

FIG. 4 is a cross-sectional view, taken along line 4-4 in FIG. 3, of the axial-flow type fan having the air inlet blade structure tipped with leading corners in accordance with the preferred embodiment of the present invention; and

FIG. 5 is a cross-sectional view, similar to that shown in FIG. 4, of an axial-flow type fan having the air outlet blade structure tipped with leading corners in accordance with the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2 through 4, reference numerals of the preferred embodiment of the present invention have applied the identical numerals of the conventional fan structure, as shown in FIG. 1. The construction of the fan structure in accordance with the preferred embodiment of the present invention has similar configuration and same function as that of the conventional fan structure and detailed descriptions may be omitted.

Referring to FIGS. 2 through 4, an axial-flow type fan in accordance with a preferred embodiment of the present invention includes a fan housing 10 and a fan wheel 20.

Referring again to FIGS. 2 through 4, the construction of the fan housing 10 shall be described in detail. The fan housing 10 is made of plastic or metal material, and formed with a square or circular hollow body. The fan housing 10 includes an air inlet side 11 and an air outlet side 11′ at its either side, as best shown in FIGS. 2 and 4. Further, the fan housing 10 consists of an air-boosting inlet 12, an air channel 13, a base 14, a plurality of supporting ribs 15 and an air-expanding outlet 16. The air inlet side 111 of the fan housing 10 provides with the air-boosting inlet 12 which is formed with an annular tapered surface for increasing air inflow and air pressure. The air-boosting inlet 12 further communicates with the air channel 13. Meanwhile, the air outlet side 11′ of the fan housing 10 provides with the air-expanding outlet 16 which is formed with an annular expanded surface for increasing air outflow. The base 14 is disposed in the air-expanding outlet 16 to support a motor stator 30 which is combined with the fan wheel 20 as well as a motor rotor (not labeled), as best shown in FIG. 2. The supporting ribs 15 are arranged about a rotary axis of the fan housing 10, and thus connect between the base 14 and the fan housing 10.

Turning now to FIGS. 2 through 5, the construction of the fan wheel 20 shall be described in detail. The fan wheel 20 is made of plastic or metal material, and consists of a hub 21 and a plurality of fan blades 22 arranged about a rotary axis of the hub 21. The construction of the hub 21 is a barrel-shaped object having an outer circumference on which equi-spaced and titled the fan blades 22 each of which forms a curve vane. The curve vane of each fan blade 22 has a tipped leading corner 221′, an inlet bottom point 222, a ridge 223 and an outlet bottom point 224. Particularly, each of the fan blades 22 has a tipped leading corner 221′ to constitute an air inlet blade structure which forms a topmost portion in a longitudinal direction. Namely, the tipped leading corner 221′ of the fan blade 22 is closely aligned with a horizontal plane of the air inlet side 11, as best shown in FIG. 4. And the tipped leading corner 221′ of the fan blade 22 also forms a forefront portion in a rotational direction and is radially approaching an annular surface of the air-boosting inlet 12 of the fan housing 10, as best shown in FIG. 3. Furthermore, a curved leading edge 220′ of the fan blade 22 extends along a curve line connecting between the tipped leading corner 221′ and the inlet bottom point 222. Regarding the curved leading edge 220′, the tipped leading corner 221′ forms a forefront point, as best shown in FIG. 3. Between the an inlet bottom point 222 and the outlet bottom point 224, each of the fan blade 22 tilts on the outer circumference of the hub 21, as best shown in FIG. 2. Additionally, the ridge 223 protrudes on a leeward surface of the fan blade 22 connecting between an inlet leading corner point of the tipped leading corner 221′ and the outlet bottom point 224, as best shown in FIG. 5.

Referring again to FIGS. 4 and 5, when the fan housing 10 and the fan wheel 20 are assembled, there are several assembled relationships between the fan housing 10 and the fan wheel 20. First, an inlet leading corner point C of the tipped leading corner 221′ is situated between a starting point A and a terminal point B of the air-boosting inlet 12 in a longitudinal direction, thereby precisely reducing air turbulence on the surface of the air-boosting inlet 12. Second, the leading point C of the tipped leading corner 221′ and the position D of the inlet bottom point 222 are situated on a common plane, thereby the tipped leading corner 221′ effectively reducing air turbulence within the air-boosting inlet 12. Alternatively, the leading point C of the tipped leading corner 221′ is slightly higher than the position D of the inlet bottom point 222 in the longitudinal direction, thereby the tipped leading corner 221′ effectively reducing air turbulence within the air-boosting inlet 12. By use such an assembled relationship, when the fan blades 22 drive a mass of the inlet air entering into the air-boosting inlet 12, the air-boosting inlet 12 compresses the inlet air for increasing air pressure in the air channel 13 of the fan housing 10. Subsequently, the forefront portion of the tipped leading corner 221′ radially approaching the air-boosting inlet 12 can avoid generating air noise and air turbulence. Meanwhile, the curved leading edge 220′ of the fan blade 22 with the tipped leading corner 221′ can eliminate a transverse airflow in the air-boosting inlet 12 when rotated. Also, the ridge 223 of the fan blade 22 can guide airflow in the air-boosting inlet 12, thereby the smooth airflow exhausting from the air-expanding outlet 16. Consequently, the tipped leading corner 221′ of the fan blade 22 carries out a preferred air-shearing effect that can reduce air noise in the air-boosting inlet 12 of the present invention.

Referring back to FIG. 1, the conventional axial-flow type fan includes the air-boosting inlet 12, and the fan blades 22 having the air inlet corner portions 221′ which may cause air turbulence on an inner circumference of the air-boosting inlet 12 of the fan housing 10 that generates air noise. Furthermore, the conventional axial-flow type fan includes the straight leading edge 220 of the each fan blade 22 which may aggravates the air turbulence generated on the annular surface of the air-boosting inlet 12. However, as best shown in FIG. 4, the present invention employs each of the fan blades 22 having the tipped leading corner 221′ proximate the annular surface of the air-boosting inlet 12 that may reduce generating air turbulence and air noise. In addition to the tipped leading corner 221′, each of the fan blades 22 further includes curved leading edge 220′ extending along a curve line in the rotational direction, and corresponding to the air-boosting inlet 12 that may eliminate a transverse airflow in the air-boosting inlet 12 when rotated.

Although the invention has been described in detail with reference to its presently preferred embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.

Claims

1. An axial-flow type fan, comprising:

a fan housing including an air inlet side and an air outlet side at its either side;

an air-boosting inlet provided on the air inlet side of the fan housing;

an air channel connecting between the air-boosting inlet and the air outlet side;

a fan wheel accommodating in the channel and including a hub;

a plurality of fan blades arranged about a rotary axis of the fan wheel and tilted on the hub, and each of the fan blades having an inlet bottom point connecting to the hub of the fan wheel; and

a plurality of tipped leading corners, each provided on the fan blade to form a topmost portion in a longitudinal direction of the fan housing and a forefront portion in a rotational direction of the fan wheel, the tipped leading corner situated in the air-boosting inlet and including a curved leading edge connecting between an inlet leading corner point of the tipped leading corner and the inlet bottom point;

wherein when the fan wheel is rotated, the tipped leading corners of the blades are able to eliminate air turbulence and air noise in the air-boosting inlet of the fan housing.

2. The axial-flow type fan as defined in claim 1, wherein the air-boosting inlet forms with an annular tapered surface along the longitudinal direction of the fan housing.

3. The axial-flow type fan as defined in claim 1, wherein each of the fan blades further includes an outlet bottom point so that the fan blade tilts between the inlet bottom point and the outlet bottom point of an outer circumference of the hub.

4. The axial-flow type fan as defined in claim 3, wherein the each of the fan blades further includes a ridge protruded on a leeward surface of the fan blade connecting between an inlet leading corner point of the tipped leading corner and the outlet bottom point, thereby the ridge stabilizing airflow.