Abstract:
A fan frame structure includes a plastic frame and a metal reinforcing member. The inner side of the frame defines a flow passage for receiving a fan wheel. The metal reinforcing member is joined to the frame intimately. The inner side of the frame is arranged to have a largest diameter so that the flow passage provides more space for accommodating a larger sized fan wheel. Hence, strength of the frame is reinforced, vibration and noise are reduced during a fan wheel running and integral effect of heat dissipation is enhanced largely.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is related to a fan frame structure and particularly to a fan frame, which provides a plastic frame part and a metal reinforcing member.  
         [0003]     2. Brief Description of the Related Art  
         [0004]     The fan is an essential part of air cooling radiator device and plays an important role for heat dissipation effect. The fan is the only movable part in the radiator device. Meanwhile, noise of the radiator device is influenced directly by the running fan. The fan induces air to move through the cooling fins with a specific speed and a specific way for heat exchange being performed between the air and the cooling fins such that accumulated heat at the cooling fins can be carried away to achieve heat removal with forced convection.  
         [0005]     Air flow and air pressure decide a fan being strong or weak. The air flow refers a product of an area of the air passing through and a velocity of the air passing through the area. When the velocity is constant, the outer diameter of the fan wheel is larger leads to the area larger and more air flow can be reached. More air flow allows the cool air absorbs more heat so that the moving air can carry with more heat and effect of heat dissipation is enhanced. The air pressure refers addition of a static pressure and a dynamic pressure of the air so that greater air pressure leads to the fan having stronger air delivering capability.  
         [0006]     In order to promote the gross effect of heat dissipation, the big sized fan has been employed to enhance heat dissipation efficiency. However, due to space limitation, not all the cooling systems are able to use the big sizes fan even if the smaller sized fan is unable to reach the expect effect of heat dissipation.  
         [0007]     The inventor has found that if the inner side of the fan frame, i.e., the flow passage of air, is increased radially under a condition of the size of the fan frame being unchanged, that is, the material between the outer side and the inner side becomes thinner. In other words, the air inlet and the air outlet areas can be increased and a bigger size fan wheel can mounted to the inner side for generating more air flow.  
         [0008]     Further, the inventor has found that most of the fan frame is made of plastic and a little portion of the fan frame is made of metal. The fan frame with plastic material is light but the strength thereof becomes weak in case of the fan frame being changed to be thinner. It is easy for the plastic fan frame being deformed and it is easy for the plastic fan frame to become soft in a high ambient temperature for a long period of time. Under these circumstances, normal operation of the fan is affected significantly.  
         [0009]     The metal fan frame provides enough strength but it is heavy and easy to produce louder noise while the air passing the fan frame to hit the inner wall of the fan frame. In addition, the metal fan frame is more costly than the plastic fan frame and manufacturing process of the metal fan frame is more complicated than the plastic fan frame.  
       SUMMARY OF THE INVENTION  
       [0010]     In order to solve the preceding problems, an object of the present invention is to provide a fan frame structure with which the inner side of the fan frame expands toward the outer side thereof to the most for the flow passage thereof being able to receive a fan wheel with a bigger diameter and promoting heat dissipation effect.  
         [0011]     Another object of the present invention is to provide a fan frame structure in which the fan frame is composed of a plastic frame part and a metal reinforcing member for strengthening the fan frame and lessening noise and vibration.  
         [0012]     Accordingly, the fan frame structure according to the present invention includes a plastic frame member and a metal reinforcing member. The frame member has an outer side and an inner side. The inner side of the frame member defines a flow passage for receiving a fan wheel. The metal reinforcing member is joined to the frame intimately. The inner side of the frame is arranged to have a largest diameter so that the flow passage provides more space for accommodating a larger sized fan wheel. Hence, strength of the frame is reinforced, vibration and noise are reduced during a fan wheel running and integral effect of heat dissipation is enhanced largely. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     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:  
         [0014]      FIG. 1  is a disassembled perspective view of the first embodiment of a fan frame according to the present invention;  
         [0015]      FIG. 2  is a fragmentary disassembled sectional view of the first embodiment of a fan frame according to the present invention;  
         [0016]      FIG. 3  is a fragmentary assembled sectional view of the first embodiment of a fan frame according to the present invention;  
         [0017]      FIG. 4  is a disassembled perspective view of the first embodiment of a fan frame according to the present invention illustrating another shape thereof;  
         [0018]      FIG. 5  is a disassembled perspective view of the second embodiment of a fan frame according to the present invention;  
         [0019]      FIG. 6  is a disassembled perspective view of the second embodiment of a fan frame according to the present invention illustrating another shape thereof;  
         [0020]      FIG. 7  is a disassembled perspective view of the second embodiment of a fan frame according to the present invention illustrating a further shape thereof;  
         [0021]      FIG. 8  is a disassembled perspective view of the third embodiment of a fan frame according to the present invention illustrating the first shape thereof;  
         [0022]      FIG. 9  is a disassembled perspective view of the third embodiment of a fan frame according to the present invention illustrating the second shape thereof;  
         [0023]      FIG. 10  is a disassembled perspective view of the third embodiment of a fan frame according to the present invention illustrating the third shape thereof;  
         [0024]      FIG. 11  is a disassembled perspective view illustrating the first shape of the third embodiment of a fan frame according to the present invention providing ventilating apertures;  
         [0025]      FIG. 12  is a disassembled perspective view illustrating the second shape of the third embodiment of a fan frame according to the present invention providing ventilating apertures;  
         [0026]      FIG. 13  is a disassembled perspective view illustrating the third shape of the third embodiment of a fan frame according to the present invention providing ventilating apertures;  
         [0027]      FIG. 14  is a sectional view of illustrating fan wheels disposed in the fan frame of the first embodiment in series;  
         [0028]      FIG. 15  is a diagram illustrating characteristics of the fan with fan frame of the invention and the conventional fan frame via air pressure curves in terms of flow rate; and  
         [0029]      FIG. 16  is a diagram illustrating characteristics of the fan with fan frame of the invention and the conventional fan frame via noise curves in terms of fan speeds. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]     Referring to FIGS.  1  to  3 , the first embodiment of a fan frame according to the present invention provides a frame member  11 , which is made of plastics and has an inner frame side  111  and an outer frame side  112 . The inner frame side  111  defines a space  113  for receiving a fan wheel  12 . An inlet  114  and an outlet  115  are formed at two lateral sides of the space  113  respectively. The outer frame side  112  defines the size of the frame member  11 . The frame member  11  has a receiving part  25  for accommodating a metal reinforcing member  13 , which is shaped as strip ring, such that once the metal reinforcing member  13  is joined to the frame member  11  tightly, the metal reinforcing member  13  constitutes the inner frame side  111  to face the fan wheel  12  for strengthening the frame member  11 .  
         [0031]     The plastic frame member  11  provides a gross volume greater than the metal reinforcing member  13 . Each of the four sides of the frame member  11  provides the shortest distance between the frame inner side  111  and the frame outer side  112 , that is, spots a, b, c, d indicated by an arrow respectively are the shortest distances between the frame inner side  111  and the frame outer side  112  and it means the spots a, b, c, and d are thinnest areas of the frame member  11 .  
         [0032]     As the foregoing, the metal reinforcing member  13  is disposed at the frame inner side  111  after the plastic frame  11  being joined to the metal reinforcing member  13 , that is, the metal reinforcing member  13  is disposed opposite the fan wheel  12  and the frame inner side  111  is composed of the metal member  13 .  
         [0033]     Referring to  FIG. 4 , the plastic frame  11  provides two receiving parts  26 , which are dovetail grooves shown in the figure, at each outer side thereof. An outer metal casing  14  provides two engaging parts  27 , which are dovetails as shown in the figures, at each of the four inner sides thereof corresponding to the receiving parts  26 . Once the engaging parts  27  engage with the receiving parts  26 , the outer casing  14  is joined to the frame  11  tightly to surround the spots a, b, c and d.  
         [0034]     Referring to  5 , the second embodiment of a fan frame structure according to the present invention is illustrated. The entire structure and functions of the second embodiment is about the same as the first embodiment. The difference of the second embodiment from the first embodiment is in that four corners of the plastic frame member  11  are independently disposed to space apart from each other with an equal distance. The four corners connect with a fan wheel seat  119  via a connecting part  118  respectively and a fan wheel  12  is rotationally joined to the seat  119 .  
         [0035]     The preceding frame member  11  provides a receiving slot  25  at each of the four corners without passing through either the inlet  114  or the outlet  115 . The receiving slot  25  shown in  FIG. 5  has a non-passing section without passing through the outlet  115 . The metal reinforcing member  13  provides a recess  132  corresponding to the non-passing section of the receiving slot  25 . When the metal reinforcing member  13  is inserted into the receiving slot  25  to fit with the frame member  11  tightly, the recess  132  is joined to the non-passing section of the receiving slot  25  respectively. The metal reinforcing member  13  constitutes the thinnest spots a, b, c and d of the frame member  11  between two of the corners respectively.  
         [0036]     Referring to  FIG. 6 , a pair of metal reinforcing members  13 , which are shaped as bent strips, are employed instead of the metal member  13  shown in  FIG. 5 . One of the metal reinforcing members  13  has the thinnest spots a, b and another metal reinforcing member  13  has the thinnest spots c, d. A pair of diagonal corners of the frame member  11  provides a receiving slot  25  the same as that shown in  FIG. 5  and another pair of diagonal corners provides two opposite recess steps respectively with a projection at the bottom of the respective recess step. Each reinforcing member  13  has a lower cut-out corner at both end sides thereof corresponding to the projection respectively in addition to having the recess  132  for being inserted into the receiving slot  25 . Hence, the cut-out corners fit with the projections while the metal reinforcing members  13  mounting to the frame  11 . Further, referring to  FIG. 7 , two pairs of metal reinforcing plates  13 ,  13  are provided instead of the metal members  13  shown in  FIG. 6  with each of the metal reinforcing plates  13  having two cut-out lower corners. The four corners of the frame member  11  provide two opposite recess steps with a projection at the bottom of the respective recess step corresponding to two of the cut-out corners for the metal reinforcing plates  13  fit with four sides of the frame  11  to constitute the thinnest spots a, b, c, and d respectively.  
         [0037]     Referring to FIGS.  8  to  13 , the third embodiment of a fan frame structure according to the present invention is illustrated. The entire structure and functions of the third embodiment is about the same as the preceding embodiments. The identical parts are designated the same numerals and no detail will be described further. The difference of the third embodiment from the preceding embodiments is in that the metal reinforcing member  13  is disposed between the inlet  114  and the outlet  115 . The metal reinforcing member  13  shown in  FIG. 8  provides a shape the same as the square plastic frame member  11  and the inlet  14  is at a side of the metal reinforcing member  13 . A plurality of receiving parts  26 , which are locating holes at the four corners of the frame member  11  and a plurality of engaging parts  27 , which are locating pins, extending downward from the bottom of the four corners of the metal reinforcing member  13  corresponding to the receiving parts  26 . Hence, the metal reinforcing member  13  is capable of being joined to the frame  11 . The metal reinforcing member  13  shown in  FIG. 9  is arranged with the outlet  115  and four corners of the metal member have a plurality of engaging members  27 , which are locating pins too, and the four corners of the frame provides a plurality of receiving parts  26 , which are locating holes extending inward from the bottom of the frame  11 . The metal reinforcing member  13  shown in  FIG. 10  is disposed between two plastic frame sections  11 . One of the frame sections  11  is arranged with the inlet  114  and the other one of the frame sections  11  is arranged with the outlet  115 . Further, the four corners of the metal reinforcing member  13  provide a plurality of engaging parts  27 , which are locating pins, at the top and the bottom thereof. The frame sections  11  provide receiving parts  26 , which are locating holes, corresponding to the engaging parts  27  respectively for the metal member  13  being capable of being joined to the two frame sections.  
         [0038]     Referring to FIGS.  11  to  13 , the metal reinforcing member  13  in  FIG. 11  is similar to that shown in  FIG. 8 , the metal reinforcing member  13  in  FIG. 12  is similar to that shown in  FIG. 9  and the metal reinforcing member  13  shown in  FIG. 13  is similar to that shown in  FIG. 10 . The difference of the metal reinforcing member  13  shown in FIGS.  11  to  13  respectively from that shown in FIGS.  8  to  10  is in that the metal reinforcing member  13  has a plurality of apertures  131  at the lateral sides thereof for admitting fluid in order to increasing air flow.  
         [0039]     Referring to  FIG. 14 , two fan wheels  12  are arranged in series in the frame  11  instead of single fan wheel  12  in the first embodiment. Of course, it is available for arranging more than two fan wheels  12  in series in case of enough space is provided in the frame  11 .  
         [0040]     In addition, the receiving part  25  and the metal reinforcing member  13  in the preceding embodiments can be coated with joining bond for the metal member  13  being secured to the receiving part  25  firmly. Alternatively, either the receiving part  25  or the metal reinforcing member  13  can be arranged at least an accommodating portion and the other one is arranged at least an engaging portion for securing the metal reinforcing member  13  to receiving part  25  firmly.  
         [0041]     Furthermore, the metal reinforcing member  13  in the preceding embodiments can be made of high strengthen compound material such as polymeric fiber and/or carbon fiber and/or plastic fiber and/or carbon-plastic fiber instead of metal.  
         [0042]     Referring to  FIG. 15 , curve of the air pressure in relation to flow rate is for the fan F 1 , which provides the fan frame of the present invention, and curve of the air pressure in relation to flow rate is for the fan F 2 , which provides the conventional fan frame. Due to the diameter of the inner side in the fan frame of the present invention is greater than that of the conventional fan frame and a bigger sized fan wheel is able to be mounted to the fan frame of the present invention, the air pressure induced by the fan F 1  is greater than that induced by the fan with the conventional fan frame under a condition of the same flow rate and, by the same token, the air flow of the fan F 1  is greater than that of the fan with the conventional fan frame under a condition of the same air pressure. Hence, entire fan characteristics of the fan F 1  are much higher than those of the fan F 2 .  
         [0043]     Referring to  FIG. 16 , curve of noise in relation to fan speed for the fan F 1  provides the fan frame of the present invention and curve of noise in relation to fan speed for the fan F 2  provides the conventional fan frame. Taking a range of fan speed between 6,000 rpm and 16,000 rpm for explanation, it can be seen the noise of the fan F 1  is between 23 dBA and 45 dBA but the noise of the fan F 2  is between 26 dBA and 49 dBA. That is, the fan F 1  generates lower noise than the fan F 2  because of the fan frame of the present invention is composed of a plastic frame and a metal member.  
         [0044]     As the foregoing, it is appreciated that comparing to the prior art, the fan frame structure of the application has the following advantages:  
         [0045]     1. The plastic frame member  11  is joined to the metal reinforcing member  13 , which also can be made of compound material, intimately for lessening noise generated from the fluid impacting the frame member  11  and diminishing consonant vibrations during the fan wheel  12  running in addition to intensifying strength thereof.  
         [0046]     2. The frame member  11  with the metal reinforcing member  13  or the compound member provides higher strength such that the inner side  111  of the frame member  11  can be arranged to expand radially and outwardly toward the outer sides  112  to the most to obtain the bigger diameter of the inner side  111  than the prior art. In this way, the inlet and outlet of the frame member  11  becomes larger and more flow rate and higher air pressure can be obtained. Further, the flow passage  113  surrounded by the inner side  111  becomes more space for accommodating larger fan wheel  12  and increasing the flow rate.  
         [0047]     3. The thinnest spots a, b, c and d of the frame member  11  can be obtained once the inner side of the frame member  11  expands radially toward the outer sides  112  to the most under support of the metal frame  15 . Hence, it is capable of overcoming the deficiency of the conventional plastic fan frame providing insufficient strength and being easily deformed after being subjected to heat for a long period of time.  
         [0048]     4. Due to the volume of the plastic frame member  11  is more than that of the metal reinforcing member  13 , the entire fan frame of the present invention is lighter than the conventional metal fan frame so that not only the cost of the fan frame can be lowered but also it is capable of overcoming the problems of noise and vibrations, which the conventional metal fan frame is unable to breakthrough.  
         [0049]     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.