Patent Application
20140072434
1. Field of the Invention
The present invention relates generally to a fan impeller structure of a centrifugal fan, and more particularly to a double-layer fan impeller structure of a centrifugal fan in which at least one layer of blades of the upper and lower layers is selectively arranged at unequal intervals so as to lower the single tone of the blade passing frequency (BPF) and greatly reduce noise.
2. Description of the Related Art
Along with the rapid development of electronic industries, the performance of the electronic components has been more and more enhanced. The electronic components have operated at higher and higher speed. In the meantime, the heat generated by the electronic components has become higher and higher. In case the heat is not dissipated in time, the operation performance of the electronic components will be deteriorated. In some more serious cases, the electronic components may even burn out. In order to dissipate the heat, a miniaturized centrifugal fan is installed in a limited space of the system for carrying away the heat. The centrifugal fan includes a frame body, a fan hub and multiple blade bodies annularly disposed around outer circumference of the fan hub. Each of upper and lower sides of the frame body is formed with an air inlet. A lateral side of the frame body is formed with an air outlet. In operation, the blade bodies rotate to drive the ambient air to flow. The axial airflow going into the frame body from the air inlet is turned to radial airflow, which is exhausted from the air outlet.
When the centrifugal fan operates, the non-uniform wake flowing out from the fan impeller will interact with the tongue to make noise. In the case that the gap between the fan impeller and the tongue is relatively narrow, the noise will be affected by the tongue oscillation caused by the impact of the non-uniform wake onto the tongue and the pressure difference around the tongue. In the case that the gap is 20% the radius of the fan impeller, only the non-uniform wake will affect the major noise source and the non-uniform wake only has little affection on the major noise source. In addition, the wake strength can be lowered by means of adding short vanes between the blades. This can minimize the affection of the non-uniform wake on the pressure turbulence and the noise. According to the above, the conventional technique has the following shortcomings:
It is therefore a primary object of the present invention to provide a fan impeller structure of centrifugal fan, which can effectively reduce noise.
To achieve the above and other objects, the fan impeller structure of centrifugal fan of the present invention includes a hub, a first blade body set and a second blade body set.
The hub has an extension section. The extension section has a first side and a second side. The first blade body set is disposed on the first side. The first blade body set includes multiple first blade bodies. The first blade bodies define therebetween multiple first air inlets and multiple first air outlets. The first air outlets are arranged at unequal intervals. The second blade body set is disposed on the second side. The second blade body set includes multiple second blade bodies. The second blade bodies define therebetween multiple second air inlets and multiple second air outlets. The second air outlets are arranged at equal intervals.
Still to achieve the above and other objects, the fan impeller structure of centrifugal fan of the present invention includes a hub, a first blade body set and a second blade body set.
The hub has an extension section. The extension section has a first side and a second side. The first blade body set is disposed on the first side. The first blade body set includes multiple first blade bodies. The first blade bodies define therebetween multiple first air inlets and multiple first air outlets. The first air outlets are arranged at unequal intervals. The second blade body set is disposed on the second side. The second blade body set includes multiple second blade bodies. The second blade bodies define therebetween multiple second air inlets and multiple second air outlets. The second air outlets are arranged at unequal intervals.
Still to achieve the above and other objects, the fan impeller structure of centrifugal fan of the present invention includes a hub, a first blade body set and a second blade body set.
The hub has an extension section. The extension section has a first side and a second side. The first blade body set is disposed on the first side. The first blade body set includes multiple first blade bodies. The first blade bodies define therebetween multiple first air inlets and multiple first air outlets. The first air outlets are arranged at equal intervals. The second blade body set is disposed on the second side. The second blade body set includes multiple second blade bodies. The second blade bodies define therebetween multiple second air inlets and multiple second air outlets. The second air outlets are arranged at unequal intervals.
The first air outlets of the first blade body set or the second air outlets of the second blade body set are selectively arranged at unequal intervals. This can lower the single tone of the blade passing frequency (BPF). Moreover, the double-layer fan impeller structure can increase the blade passing frequency (BPF) and lower sound pressure weighting so as to greatly reduce noise. In addition, the upper and lower blades can be more flexibly designed according to the boundary condition.
The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein:
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The hub 11 has an extension section 111 having a first side 1111 and a second side 1112. The extension section 111 extends from the circumference of the hub 11 in a direction away from the hub 11.
The first blade body set 12 is disposed on the first side 1111. The first blade body set 12 includes multiple first blade bodies 121. The first blade bodies 121 define therebetween multiple first air inlets 122 and multiple first air outlets 123. The first air outlets 123 are arranged at unequal intervals.
The second blade body set 13 is disposed on the second side 1112. The second blade body set 13 includes multiple second blade bodies 131. The second blade bodies 131 define therebetween multiple second air inlets 132 and multiple second air outlets 133. The second air outlets 133 are arranged at equal intervals.
The first blade body set 12 extends from the first side 1111 of the extension section 111 in a direction away from the hub 11. Each first blade body 121 has a first end 1211 and a second end 1212. The first air inlet 122 is defined between the first ends 1211 of each two adjacent first blade bodies 121. The first air outlet 123 is defined between the second ends 1212 of each two adjacent first blade bodies 121. The second blade body set 13 extends from the second side 1112 of the extension section 111 in a direction away from the hub 11. Each second blade body 131 has a third end 1311 and a fourth end 1312. The second air inlet 132 is defined between the third ends 1311 of each two adjacent second blade bodies 131. The second air outlet 133 is defined between the fourth ends 1312 of each two adjacent second blade bodies 131.
The first ends 1211 together define a first pitch circle 124. A tangent of the first pitch circle 124 at the first end 1211 is defined as a first tangent 125. The first blade body 121 has a first blade body central line 1213. A tangent of the first blade body central line 1213 at the first end 1211 is defined as a second tangent 126. The second tangent 126 intersects the first tangent 125 to contain a first air incoming angle 12a. The second ends 1212 together define a second pitch circle 127. A tangent of the second pitch circle 127 at the second end 1212 is defined as a third tangent 128. A tangent of the first blade body central line 1213 at the second end 1212 is defined as a fourth tangent 129. The third tangent 128 and the fourth tangent 129 contain a first air outgoing angle 12b. The third ends 1311 together define a third pitch circle 134. A tangent of the third pitch circle 134 at the third end 1311 is defined as a fifth tangent 135. The second blade body 131 has a second blade body central line 1313. A tangent of the second blade body central line 1313 at the third end 1311 is defined as a sixth tangent 136. The fifth tangent 135 intersects the sixth tangent 136 to contain a second air incoming angle 13a. The fourth ends 1312 together define a fourth pitch circle 137. A tangent of the fourth pitch circle 137 at the fourth end 1312 is defined as a seventh tangent 138. A tangent of the second blade body central line 1313 at the fourth end 1312 is defined as an eighth tangent 139. The seventh tangent 138 and the eighth tangent 139 contain a second air outgoing angle 13b. In this embodiment, the first air incoming angle 12a is larger than or equal to the second air incoming angle 13a.
The first blade body central line 1213 extends along the first blade body 121 and has a curvature equal to that of the first blade body 121. The second blade body central line 1313 extends along the second blade body 131 and has a curvature equal to that of the second blade body 131. The first blade body central line 1213 is a longitudinal central line of the thickness of the first blade body 121. That is, on the basis of the first blade body central line 1213, the widths extend from the first blade body central line 1213 to two sides of the first blade body 121 are equal to each other. Similarly, the second blade body central line 1313 is a longitudinal central line of the thickness of the second blade body 131. That is, on the basis of the second blade body central line 1313, the widths extend from the second blade body central line 1313 to two sides of the second blade body 131 are equal to each other.
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The present invention has been described with the above embodiments thereof and it is understood that many changes and modifications in the above embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.
