Patent Publication Number: US-2018030999-A1

Title: Heat dissipation module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of China Patent Application No. 201620810919.1 filed on Jul. 29, 2016, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a heat dissipation module, and in particular it relates to a heat dissipation module comprising a fan on which the height of the blades&#39; upper edges is lower than the outward expansion portion on the frame inlet. 
     Description of the Related Art 
     As electronic products are rapidly being developed to have high performance, high frequency, high speed, and a thin profile, the temperature of these electronic products is getting higher and higher. This causes unstable phenomena to occur and thus influence the reliability and the lifetime of the product. Accordingly, heat dissipation has become one of the most important issues regarding electronic products, and a fan module is frequently used in a heat dissipating device. 
     Referring to  FIG. 1A , a conventional fan module includes a frame  10 , a motor  11  and an impeller  12 . When the motor  11  drives the impeller  12  to rotate and produce airflow from an air inlet to an air outlet (in the direction indicated by arrow A), the heat of the electronic product is dissipated into the environment. However, the air impacts the interior structure of the fan module and produces a noise at specific frequency, which causes discomfort to the users at most of time. 
     To reduce the noise of the fan module, the fan speed is usually reduced. Referring to  FIGS. 1B and 1C ,  FIG. 1B  shows the frequency spectrum of the fan module when the rotational speed is 20000 rpm, and  FIG. 1C  shows the frequency spectrum of the fan module when the rotational speed is 15000 rpm.  FIGS. 1B and 1C  respectively show a noise spectrum W 1  having a blade frequency W 11  at 1700 Hz and a noise spectrum W 2  having a blade frequency W 21  at 1300 Hz. 
     It should be known that the noise values L 1  and L 2  corresponding to the blade frequencies W 11  and W 21  can reflect the sound quality and the overall noise level. As shown in  FIGS. 1B and 1C , the noise value L 2  is less than the noise value L 1 , and which means conventionally the noise peak at the blade frequency can be reduced by a slower rotational speed. However, the heat dissipation efficiency becomes lower as well. 
     BRIEF SUMMARY OF THE INVENTION 
     To solve the problems of the prior art, the embodiment of the invention provides a heat dissipation module, comprising a frame, a base, and a fan. The frame has an outward expansion portion at an inner edge of the frame and adjacent to an air inlet of the heat dissipation module. The outward expansion portion forms a depressed structure and has a curved surface or a sloping surface at the inner edge. The base is connected to the frame and has a bottom surface. The fan is movably disposed on the base and is rotatable with respect to the frame. The fan has a plurality of blades. The end of the upper edge of each of the blades has a first height with respect to the bottom surface, and the outward expansion portion has a second height with respect to the bottom surface. The first height is less than the second height. 
     In one embodiment, the end of the upper edge of each of the blades forms a curved structure. 
     In one embodiment, the upper edges of the blades are parallel to the bottom surface. 
     In one embodiment, the frame has a plurality of stationary vanes disposed on an air outlet of the frame and connected to the base. A first angle is formed between the upper edges of the stationary vanes and the bottom surface, and a second angle is formed between the lower edges of the stationary vanes and the bottom surface. The first angle and the second angle are acute angles. 
     In one embodiment, the first angle and the second angle are the same degree substantially. 
     In one embodiment, a third angle is formed between the lower edges of the fan and the bottom surface, and the third angle is an acute angle. 
     In one embodiment, the first, second, and third angles have substantially the same degrees. 
     In one embodiment, the frame has a plurality of stationary vanes, and the stationary vanes are disposed on the air inlet of the frame. 
     In one embodiment, the fan has a hub forming a guiding surface on an upper edge thereof, and an outer side of the guiding surface forms a curved or sloping surface. 
     In one embodiment, the frame, the base, and the fan have metal or plastic material. 
     In one embodiment, the frame and the base are formed by injection moulding. 
     In one embodiment, the base has a sustaining portion protruding upwardly. 
     In one embodiment, the fan has a hub and a shaft disposed at the center of the hub. 
     In one embodiment, the fan has a sustaining unit, disposed in the sustaining portion to sustain the shaft, and the sustaining unit includes ball bearing, spring, snap ring or bush. 
     In one embodiment, the fan further has an iron housing, a magnetic element, and a driving unit, the iron housing is disposed in the hub and shaped corresponding to the inside surface of the hub, the magnetic element is disposed in the iron housing, and the driving unit is disposed between the iron housing and the sustaining portion, wherein the magnetic element and the driving unit impel the hub and the blades to rotate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1A  shows a conventional fan module. 
         FIG. 1B  shows a frequency spectrum of the fan module when the rotational speed is 20000 rpm. 
         FIG. 1C  shows a frequency spectrum of the fan module when the rotational speed is 15000 rpm. 
         FIG. 2A  is a perspective view of the heat dissipation module of an embodiment of the invention. 
         FIG. 2B  is a cross-sectional view of the heat dissipation module in  FIG. 2A . 
         FIG. 2C  shows a frequency spectrum of the heat dissipation module when the rotational speed is 20000 rpm. 
         FIG. 3  is a cross-sectional view of the heat dissipation module according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as being “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     Referring to  FIGS. 2A-2C ,  FIG. 2A  is a perspective view of the heat dissipation module of an embodiment of the invention,  FIG. 2B  is a cross-sectional view of the heat dissipation module in  FIG. 2A , and  FIG. 2C  shows a frequency spectrum of the heat dissipation module when the rotational speed is 20000 rpm. As shown in  FIGS. 2A and 2B , the heat dissipation module of the embodiment comprises a frame  20 , a fan  30 , and a base  40  connected to the frame  20 , wherein a bottom surface  40   a  of the base  40  is parallel to the XY plane, and the fan  30  is movably disposed on the base  40  and rotatable with respect to the frame  20 . In the embodiment, the frame  20  has a plurality of stationary vanes  21  and an outward expansion portion  22 , and the fan  30  has a plurality of blades  31 , a hub  32 , a shaft  33 , a sustaining unit  34 , an iron housing  35 , and a driving unit  37 . Moreover, the base  40  has a sustaining portion  41  protruding upwardly. 
     As shown in  FIG. 2B , the stationary vanes  21  are connected to the inner wall of the frame  20  and the base  40 . The stationary vanes  21  are disposed on the air outlet O of the heat dissipation module and for guiding air smoothly downwardly to the air outlet O and exhausting air from the heat dissipation module, wherein a first angle θ 1  is formed between an upper edge  21   a  of the stationary vane  21  and the XY plane, and a second angle θ 2  is formed between a lower edge  21   b  of the stationary vane  21  and the XY plane. The first angle θ 1  and the second angle θ 2  are acute angles having substantially the same degrees. Specifically, the outward expansion portion  22  has a depressed structure with a curved surface formed on an inner side of the frame  20 , which is adjacent to the air inlet I to increase the intake and outlet airflow and guide the airflow smoothly flowing into the heat dissipation module, wherein the frame  20  and the base  40  may have metal or plastic material, such as formed by plastic injection moulding. In an embodiment, the stationary vanes  21  can also be disposed only in the air inlet I of the heat dissipation module, or in both of the air inlet I and the air outlet O. Moreover, the outward expansion portion  22  may have a sloping surface to guide the airflow efficiently. 
     In the embodiment, the fan  30  may have metal or plastic material, and the blades  31  are disposed on the outer side of the hub  32 , wherein each upper edge  31   a  of the blade  31  has a curved structure. As shown in  FIG. 2B , an end  31   c  of the upper edge  31   a  of the blade  31  is situated on a reference surface P parallel to the XY plane. Specifically, a third angle θ 3  is formed between a lower edge  31   b  of the blade  31  and the XY plane, wherein the third angle θ 3  is an acute angle having substantially the same degrees as the first and second angles θ 1  and θ 2 . 
     The hub  32  has a substantially round structure, and an outer side on an upper portion of the hub  32  forms a guiding surface  32   a , wherein the guiding surface  32   a  is a curved surface to guide more airflow smoothly flowing into the heat dissipation module. It should be understood that the guiding surface  32   a  may also be a sloping surface in some embodiments. The shaft  33  is disposed at the center of the hub  32 , and the sustaining unit  34  is disposed in the sustaining portion  41  to sustain the shaft  33 . The sustaining unit  34  may include a ball bearing, a spring, a snap ring, or a bushing, so that the fan  30  can rotate smoothly. The iron housing  35  is disposed in the hub  32  and shaped corresponding to the inner surface of the hub  32 . The magnetic element  36  is disposed in the iron housing  35 , such as a flexible magnetic strip having plastic material. The driving unit  37  is disposed between the iron housing  35  and the sustaining portion  41 , and it may comprise silicon steel sheets and electronic components, wherein the magnetic element  36  and the driving unit  37  can drive the hub  32  and the blades  31  to rotate and produce airflow. 
     It should be understood that a first height H 1  along the Z direction is formed between the end  31   c  of the upper edge  31   a  of the blade  31  and the bottom surface  40   a  of the base  40 , and a second height H 2  along the Z direction is formed between the end  22   a  of the outward expansion portion  22  and the bottom surface  40   a , wherein the first height H 1  is less than the second height H 2 . As shown in  FIG. 2C , a noise spectrum W 3  is produced according to the configuration of the aforementioned heat dissipation module, and a blade frequency W 31  at 1700 Hz is presented in a noise value L 3  (dB). 
     It should be known that the noise value L 3  can reflect the sound quality and the overall noise level. It can be derived from  FIGS. 1B and 2C  that when the heat dissipation module of the embodiment and the conventional fan module in  FIG. 1A  have the same rotational speed of 20000 rpm, the noise value L 3  ( FIG. 2C , at a blade frequency of 1700 Hz) is obviously less than the noise value L 1  ( FIG. 1B , at a blade frequency of 1700 Hz). In other words, when the fans have the same rotational speed, the heat dissipation module of the invention can reduce the peak value (noise) corresponding to a specific blade frequency of the heat dissipation module. 
       FIG. 3  is a cross-sectional view of the heat dissipation module according to an embodiment of the invention. As shown in  FIG. 3 , the heat dissipation module comprises a frame  20 , a fan  30 , and a base  40 . The difference between this embodiment and the embodiment of  FIG. 1A  is that the upper edges  31   a  of the blades  31  in this embodiment are situated on the same reference surface P (as shown in  FIG. 3 ), parallel to the XY plane. It should be noted that a first height H 1  is formed between the end  31   c  of the upper edge  31   a  of the blade  31  and the bottom surface  40   a  of the base  40 , and a second height H 2  is formed between the end  22   a  of the outward expansion portion  22  and the bottom surface  40   a , wherein the first height H 1  is less than the second height H 2 . It also can reduce the peak value (noise) corresponding to a specific blade frequency of the heat dissipation module. 
     In summary, the invention provides a heat dissipation module, including a frame, a base, and a fan, wherein the frame has an outward expansion portion. The fan has a plurality of blades, and an end of an upper edge of the blades has a first height with respect to the bottom surface, and the outward expansion portion has a second height with respect to the bottom surface, wherein the first height is less than the second height. Thus, the airflow can be smoothly guided into the heat dissipation module, and the peak value (noise) corresponding to a specific blade frequency can be efficiently suppressed under the same operation condition when comparing with the conventional fan modules. In other words, the invention can suppress the noise caused by rotation of the fan and make the sound more comfortable to hear, so as to provide users with a better environment. 
     Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.