Centrifugal fan with low noise

[0001] 1. Field of the Invention

[0002] The present invention is related to a centrifugal fan with low noise and particularly to a centrifugal fan capable of attenuating noise.

[0003] 2. Brief Description of the Related Art

[0004] Application of the computer industry is getting popular along with the information technology being highly developed. Further, due to network being developed prosperously with a great deal of network transmissions and data processing, more computer equipment are needed for offering sufficient operation and processing capability.

[0005] Owing to manufacturing process of integrated circuit being improved, fabrication of integrated circuit is getting delicate and complicated. Various computer equipments provide more powerful functions. But, the complicated circuit leads to huge power consumption and the power consumption results in a serious problem because of temperature of the equipment rising caused by the power consumption.

[0006] Generally speaking, fast transmission of heat is very important for electronic equipment, especially which is a computer, in order to obtain the greatest performance thereof. Because heat congregating in the equipment and being incapable of being dissipated outward properly, the electronic components inside are unable to work normally and the entire equipment will be influenced under this circumference. As a result, the computer system will be shut down unexpectedly.

[0007] Hence, a heat dissipation device such as a cooling fan usually is mounted in the electronic equipment for helping heat dissipation from the electronic components. Ordinarily, the cooling fan used in the electronic equipment is an axial flow fan or a centrifugal fan. The centrifugal fan drags the air toward the radial direction or toward a direction perpendicular to the shaft of thereof.

[0008] When the fan wheel rotates, the air enters the centrifugal fan via the center of the fan wheel and acquires energy by means of centrifugal force of the air itself, the air, then, moves outward radially along the fan blades. Thus, higher air pressure is created so that the centrifugal fan is suitable for being applied in a system, which has larger resistance. Further, flow field inside the centrifugal fan is quite complicated and fluid flows radially along with the fan wheel such that it produces phenomena such as recirculation, reversed flow and separation to complicate flow field in the fan wheel and produce high noise decibel.

[0009] Referring to FIGS. 1 to 3, the conventional centrifugal fan includes a housing 11 and a fan wheel 13. The housing 11 has a housing base 111 and a lid 112. The housing base 111 and the lid member 112 provide a first inlet 111, a second inlet 1121 and an outlet 12 respectively. The first inlet 1111 is attached with a plurality of auxiliary ribs 1122. The fan wheel 13 is rotationally mounted over the auxiliary ribs 1122 in the housing and includes a hub 131 and a plurality of fan blades 132 extending outward from the hub 131 radially.

[0010] When the fan wheel 13 rotates to actuate fluid entering the housing 11 via the first inlet 1111 and the second inlet 1121, the fluid then flows outward along the inner wall of the housing 11 toward the outlet 12.

[0011] However, a problem of the conventional centrifugal fan in practice resides in that the housing 11 is flat at the surface thereof with strengthen ribs 1122 being added at the reinforced position only such that the fluid accelerates with increasing flow energy after passing through the fan blades to impact the housing 11 while the fluid is entering the housing 11 via the first inlet 1111 and the second inlet 1121 and shooting outward speedily due to the fan blades 132 rotating and it results in vibration and louder noise because of the flat surface of the housing with too wick structural tension.

[0012] In addition, rotational noise with various frequencies occur during the fan is in operation and the noise with the frequencies especially with the narrow band frequency easily transmits outward to results in the user having uncomfortable feeling caused by the narrow band noise being sharp to the hearing sense of the user.

[0013] A main object of the present invention is to provide a centrifugal fan with low noise in which the housing has a recess unit at the surface thereof to lessen transmission and creation of noise.

[0014] Another object of the present invention is to provide a centrifugal fan with low noise in which the recess unit on the surface of the housing is formed with at least a projection part and a recess part for intensifying strength of the surface of the housing.

[0015] In order to achieve the preceding object, a centrifugal fan with low noise according to the present invention includes a housing and a fan wheel. The housing forms a chamber inside to receive the fan wheel and has a recess unit at the surface thereof to decrease noise being transmitted outward.

[0016] The detail structure, the applied principle, the function and the effectiveness of the present invention can be more fully understood with reference to the following description and accompanying drawings, in which:

[0017] FIG. 1 is an exploded perspective view of the conventional centrifugal fan;

[0018] FIG. 2 is a perspective view of the conventional centrifugal fan shown in FIG. 1;

[0019] FIG. 3 is a sectional view of the conventional centrifugal fan;

[0020] FIG. 4 is an exploded perspective view of the preferred embodiment of a centrifugal fan with low noise according to the present invention;

[0021] FIG. 5 is a perspective view of the preferred embodiment of a centrifugal fan with low noise shown in FIG. 4;

[0022] FIG. 6 is a perspective view illustrating the lid member in the preferred embodiment of a centrifugal fan according to the present invention projecting from another direction;

[0023] FIG. 7 is a sectional view of the preferred embodiment of on the centrifugal fan according to the present invention; and

[0024] FIG. 8 is a perspective view illustrating an alternative configuration of the centrifugal fan according to the present invention.

[0025] Referring to FIGS. 4 to 6, the preferred embodiment of a centrifugal fan with low noise according to the present invention includes a housing 21 and a fan wheel 22. The fan wheel 22 provides a hub 221 and a plurality of fan blades 222 surrounding the hub 21 and extending outward radially from the hub 221. The housing 21 has a housing base 211 and a lid member 212 and the housing base 211 has a bottom plate 2111 with a side plate 2112 extending along the bottom plate 2111. A first inlet 2113 is provided at the bottom plate 2111 and an outlet 2114 is provided at the side plate 2112. A plurality of auxiliary ribs 2115 are arranged in the first inlet 2113 and a second inlet 2121 is provided at the lid member 212 to define a chamber 23 with the bottom plate 2111 and the side plate 2112. The chamber 23 communicates with the outlet 2114.

[0026] Both the bottom plate 2111 and the lid member 212 of the housing 21 provides at least a recess unit 24 at the surfaces thereof and the recess unit 24 provides at least a projection part 241 and a recess part 242. The surfaces are the outer surfaces and/or the inner surfaces and the projection part 241 and the recess part 242 shown in the figures are formed with grid shapes.

[0027] During being assembled, the fan wheel 22 is rotationally mounted in the chamber 23 and the lid member 212 covers at a lateral side opposite to the bottom plate 2111 and both the first inlet 2113 and the outlet 2121 face the fan wheel 22.

[0028] Referring to FIG. 7, while the fan wheel 22 is running, fluid enters the chamber 23 via the first inlet 2113 and the second inlet 2121 respectively and is accelerated to shoot outward radially after being actuated by the rotational fan wheel 22. Afterward, the fluid flows toward the outlet 2114 along the inner wall of the chamber 23. The projection part 241 and the recess part 242 of the recess unit 24 are capable of strengthening and intensifying the surface structure of the housing 21 to resist vibration during the accelerated fluid hitting inner part of the housing 21 such that noise attenuates greatly. Further, it is able to prevent from narrow frequency band noise created during the fan wheel 22 running transmitting outward via the surface of the housing 21 so that deficiency of noise transmitting outward via flat surface of the housing is overcome.

[0029] In addition, the projection part and the recess part of the recess unit can be formed with parallel shape as shown in FIG. 8 and the housing and the recess unit can be integrally made as a single piece or can be made individual pieces.

[0030] While the invention has been described with referencing to preferred embodiments thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention, which is defined by the appended claims.