Patent Publication Number: US-7909586-B2

Title: Fan and rotor thereof

Description:
This non-provisional application claims priority under U.S.C.§119(A) on patent application No(s). 094119247, filed in Taiwan, Republic of China on Jun. 10, 2005, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to a fan and a rotor thereof, and more particularly to a fan and a rotor thereof with high precision. 
     2. Related Art 
     Motors are widely used in various applications, such as a lathe, an electric drill and an electric saw in the industry, and a tape recorder, an optical drive, a hard disk drive, a pump, a blower, a dust cleaner, a refrigerator, a compressor of an air conditioner, and a fan in the daily life. 
     The fans are also widely used in dissipating heat generated from all electronic apparatuses, either the large industrial machines or the electronic products of the daily life, such as a power supply of a computer and an air conditioner. 
     As shown in  FIG. 1 , a conventional rotor  10  includes an impeller  11 , an iron casing  12 , a shaft  13  and a copper bushing  14 . The impeller  11  is composed of a hub  111  and a plurality of blades  112 . The copper bushing  14  is disposed at one end of the shaft  13 . Conventionally, the copper bushing  14  is riveted to the iron casing  12 , and then the protrusions  113  on the bottom of the hub  111  are respectively positioned in the openings  121  of the iron casing  12  correspondingly. The impeller  11  is connected to the iron casing  12  by way of hot melting or ultrasonic bonding. Thus, a complete rotor  10  is assembled. 
     However, the conventional rotor  10  has the following drawbacks. 
     First, when the impeller  11  is connected to the iron casing  12  by way of hot melting, the temperature rises so that the perpendicularity or the concentricity of the shaft  13  tends to be damaged due to different coefficients of thermal expansion of several different elements. 
     Second, when the impeller  11  is connected to the iron casing  12  by way of ultrasonic bonding, the perpendicularity or the concentricity of the shaft  13  tends to be damaged due to vibration caused by the ultrasonic bonding procedure. 
     Third, because of the multiple assemblies, in which the protrusion  113  on the bottom of the hub  111  has to be aligned with the opening  121  on the iron casing  12 , another tolerance in addition to the original tolerance of the position of the opening  121  on the iron casing  12  is obtained due to the alignment and the bonding between the impeller  11  and the iron casing  12 . 
     The damage to the perpendicularity or the concentricity of the shaft  13  and the accumulated tolerance tend to reduce production yield of the rotor  10 , or even cause the skew and wear of the shaft  13 . When the motor is rotating at the high speed, the problems caused by the skew and the wear tend to become more serious. It is thus imperative to provide a rotor structure, in which the perpendicularity or the concentricity of the shaft  13  is free from being influenced. 
     SUMMARY OF TH INVENTION 
     In view of the foregoing, the present invention provides a fan and a rotor thereof, in which the perpendicularity or the concentricity of a shaft is free from being influenced when an impeller of the rotor is assembled. 
     To achieve the above, a fan according to the present invention includes a frame, a stator and a rotor. The stator is disposed in the frame. The rotor is disposed in the frame and coupled with the stator. The rotor includes a connecting element, an impeller and a shaft. The connecting element has a flange. The impeller is disposed on a periphery of the connecting element and is embedded with the flange of the connecting element, and one end of the shaft is connected to the connecting element. 
     To achieve the above, a rotor according to the present invention includes a connecting element, an impeller and a shaft. The connecting element has a flange. The impeller is disposed on a periphery of the connecting element and is embedded with the flange of the connecting element, and one end of the shaft is connected to the connecting element. 
     As mentioned above, due to the impeller is formed on the connecting element by way of injection molding, a fan and a rotor thereof according to the present invention are unnecessary to connect the impeller and the motor housing through cooperating the protrusions on the impeller with the openings on the motor housing, and then connecting by way of hot melting or ultrasonic bonding in the prior art. Consequently, the present invention can prevent the damage to the perpendicularity or the concentricity of the shaft caused by the hot melting process or the ultrasonic bonding process. In addition, because of skipping the cooperation between the protrusion of the impeller and the opening of the motor housing, the tolerance caused by the multiple assemblies may be reduced, and thus the precision of the fan and the rotor is improved. Furthermore, because the connecting element has the flange to be embedded with the impeller, the position of the impeller may be secured without shift during the high-speed rotation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a schematic view showing the structure of a conventional rotor, 
         FIG. 2  is a schematic view showing a rotor according to a preferred embodiment of the present invention; 
         FIG. 3  is another schematic view showing the rotor according to the preferred embodiment of the present invention; and 
         FIG. 4  is a schematic view showing a fan according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A fan and a rotor thereof according to the preferred embodiment of the present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
     Referring both to  FIGS. 2 and 3 ,  FIG. 2  is a schematic view showing a rotor according to a preferred embodiment of the present invention, and  FIG. 3  is another schematic view showing the rotor according to the preferred embodiment of the present invention. A rotor  20  includes a connecting element  21 , an impeller  22  and a shaft  23 . 
     The connecting element  21  has a flange  211 . In this embodiment, the connecting element  21  is a preferred bushing and is made of a metallic material such as copper. As shown in  FIG. 2 , the connecting element  21  may further have a plurality of textures  212  arranged in parallel with the shaft  23  and disposed around the connecting element  21 . When the connecting element  21  is connected to the impeller  22 , the textures  212  enlarge the contact area between the connecting element  21  and the impeller  22  so as to intensify the connecting force between the connecting element  21  and the impeller  22 . Consequently, the impeller  22  cannot be easily separated from the connecting element  21  during the high-speed rotation of the impeller  22 . 
     As shown in  FIG. 3 , the impeller  22  is disposed around a periphery of the connecting element  21  by way of, for example, injection molding. That is, when the injection molding process is performed, the connecting element  21  is placed into a mold, and the plastic material flows into the mold and contacts with the connecting element  21  to form the impeller  22  on the connecting element  21 . 
     The flange  211  of the connecting element  21  is embedded with the impeller  22 . In this embodiment, the impeller  22  includes a hub  221  and a plurality of blades  222  disposed around the hub  221 . The flange  211  of the connecting element  21  is embedded with the hub  221  of the impeller  22 . When the rotor  20  is rotating, the impeller  22  can be firmly connected to the connecting element  21  because the flange  211  is embedded with the hub  221 . Especially when the rotor  20  is rotating at high speed, the flange  211  is needed to secure the impeller  22  and prevents the impeller  22  from shifting during the high-speed rotation of the rotor  20 . 
     One end of the shaft  23  is connected to the connecting element  21 . In this embodiment, the shaft  23  may be a motor shaft, and the connecting element  21  has a hole  213  for allowing the shaft  23  to penetrate therethrough, such that the connecting element  21  is disposed at one end of the shaft  23 . 
     As shown in  FIG. 3 , the rotor  20  may further include a motor housing  24  connected to the shaft  23 . In this embodiment, the motor housing  24  has an opening  241  for allowing the shaft  23  to penetrate therethrough, such that the motor housing  24  is adjacent to the connecting element  21 . 
     Because the impeller  22  of the rotor  20  may be directly formed on the connecting element  21  by way of injection molding, the present invention is unnecessary to connect the impeller  22  and the motor housing  24  through cooperating the protrusions on the impeller  22  with the openings on the motor housing  24 , and then connecting by way of hot melting or ultrasonic bonding in the prior art. Consequently, the present invention can prevent the damage to the perpendicularity or the concentricity of the shaft  23  caused by the hot melting process or the ultrasonic bonding process. In addition, because of skipping the cooperation between the protrusions of the impeller  22  and the openings of the motor housing  24 , the tolerance caused by the multiple assemblies is reduced, and thus the precision of the rotor  20  is improved. 
     The fan according to the preferred embodiment of the present invention will be described with reference to  FIGS. 2 to 4 .  FIG. 4  is a schematic view showing a fan according to a preferred embodiment of the present invention. 
     As shown in  FIGS. 2 to 4 , a fan  30  includes a frame  31 , a stator  32  and a rotor  20 . The stator  32  is disposed in the frame  31 . In this embodiment, the stator  32  has a plurality of coils  321 . The rotor  20  is disposed in the frame  31  and coupled with the stator  32 . The current is flowing into the coils  321  for driving the rotor  20  to rotate relatively to the stator  32 . 
     As shown in  FIG. 2 , the rotor  20  includes a connecting element  21 , an impeller  22  and a shaft  23 . The connecting element  21  has a flange  211 . In this embodiment, the connecting element  21  may be a bushing and be made of a metallic material such as copper. The connecting element  21  may further have a plurality of textures  212  disposed around the connecting element  21 . The textures  212  are connected to the impeller  22 . The textures  212  may be arranged in a direction of being slant, parallel or perpendicular to the shaft  23 . The textures  212  can enlarge the contact area between the connecting element  21  and the impeller  22  so as to intensify the connecting force between the connecting element  21  and the impeller  22 . Consequently, the impeller  22  cannot be easily separated from the connecting element  21  during the high-speed rotation of the impeller  22 . 
     As shown in  FIG. 3 , the impeller  22  is disposed around a periphery of the connecting element  21  by way of, for example, injection molding. That is, when the injection molding process is performed, the connecting element  21  is placed into a mold, and the plastic material flows into the mold and contacts with the connecting element  21  to form the impeller  22  on the connecting element  21 . 
     The flange  211  of the connecting element  21  is embedded with the impeller  22 . In this embodiment, the impeller  22  includes a hub  221  and a plurality of blades  222  disposed around the hub  221 . The flange  211  of the connecting element  21  is embedded with the hub  221  of the impeller  22 . When the rotor  20  is rotating, the impeller  22  can be firmly connected to the connecting element  21  because the flange  211  is embedded with the hub  221 . Especially, when the rotor  20  is rotating at the high speed, the flange  211  is needed to secure the impeller  22  and prevents the impeller  22  from shifting during the high-speed rotation of the rotor  20 . 
     One end of the shaft  23  is connected to the connecting element  21 . In this embodiment, the shaft  23  may be a motor shaft, and the connecting element  21  has a hole  213 . The shaft  23  penetrates through the hole  213  of the connecting element  21  such that the connecting element  21  is disposed at one end of the shaft  23 . 
     As shown in  FIG. 3 , the rotor  20  may further include a motor housing  24  connected to the shaft  23 . In this embodiment, the motor housing  24  has an opening  241  for allowing the shaft  23  to penetrate therethrough, such that the motor housing  24  is adjacent to the connecting element  21 . 
     In summary, due to the impeller is formed with the connecting element by way of injection molding, a fan and a rotor thereof according to the present invention are unnecessary to connect the impeller to the motor housing through cooperating the protrusions on the impeller with the openings on the motor housing, and then connecting by way of hot melting or ultrasonic bonding in the prior art. Consequently, the present invention can prevent the damage to the perpendicularity or the concentricity of the shaft caused by the hot melting process or the ultrasonic bonding process. In addition, because of skipping the cooperation between the protrusions of the impeller and the openings of the motor housing, the tolerance caused by the multiple assemblies is reduced, and thus the precision of the fan and the rotor is improved. Furthermore, because the connecting element has the flange to be embedded with the impeller, the position of the impeller may be secured without shift during the high-speed rotation. 
     Although the present invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the present invention.