Abstract:
A motor structure and a fan are provided. The motor structure includes a shaft, a motor control panel, a stator, a rotor and a motor housing. The motor control panel has a first fastening portion and is engageable with the shaft. The stator has a second fastening portion coupled to the first fastening portion so as to fasten the motor control panel to the stator, thereby reducing the overall size and saving costs of materials. The rotor corresponds in position to the stator and is pivotally connected to the shaft. The motor housing is pivotally connected to the shaft and encloses the shaft, the motor control panel, the stator, and the rotor. The fan includes the motor structure and a fan blade element.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to motor structures and fans, and more particularly to an outer rotor type brushless DC motor structure and a fan with the motor structure. 
         [0003]    2. Description of Related Art 
         [0004]    A motor converts electric energy into mechanical energy so as to provide rotary motion and essentially comprises a stator and a rotor. The electric energy is supplied to the motor to induce an electromagnetic field between the stator and the rotor. The electromagnetic field produces attraction/repulsion to generate mechanical energy, thereby enabling rotation of the rotor. In addition to providing rotary motion directly, a motor converts rotary mechanical energy into various mechanical motions, such as linear motion and vibrating motion, by a combination of mechanisms. Generally, there are three types of motors according to power sources, namely DC motors, AC motors, and brushless DC (BLDC) motors. 
         [0005]    Regarding a conventional DC motor, the stator is formed from permanent magnets, and the rotor is enclosed with a field winding and provided with a commutator in physical contact with carbon brushes of different polarity so as to transmit DC power to the field winding, thereby generating an electromagnetic force. The attraction/repulsion between the electromagnetic force and the permanent magnets of the stator causes the rotor to rotate. The commutator rotates along with the rotor and thereby changes the brushes in physical contact while rotating. This enables alternation of the direction of current, and in consequence the rotor continues to turn in the same direction. However, mechanical commutation unnecessarily wastes energy due to mechanical friction. In addition, sparks and noises are easily generated on the contact surface between the commutator and the brushes. Furthermore, a maintenance cost is incurred as a result of cleanup and replacement of the brushes. 
         [0006]    The rotor of an AC motor is formed from permanent magnets, and a field winding is wound on the stator, wherein alternating current is transmitted into the field winding for generating a magnetic field which alternates between opposite directions. Such an AC motor spares the use of any commutator or brushes and accordingly is free of the above-described drawbacks of a DC motor. However, it is difficult to change the speed of an AC motor, because both AC frequency and AC voltage need to be modulated. 
         [0007]    Unlike the above-described DC and AC motor, a BLDC motor operates by electronic commutation. Specifically speaking, the rotor of a BLDC motor is formed by permanent magnets, and a field winding is wound around the stator as in an AC motor. By changing the current input direction of the field winding, the direction of the electromagnetic force can be changed to keep the rotor rotating. Hence, a BLDC motor spares the use of brushes and accordingly overcome the drawbacks caused by the brushes. In addition, compared with an AC motor, the control operation of such a BLDC motor is simpler. Therefore, BLDC motors are widely applied in the industry. 
         [0008]    The electronic commutation control method needs to detect polarity of the magnetic field corresponding to the position of the rotor for precisely controlling the direction of the electromagnetic force. Therefore, a controller is indispensable to a BLDC motor. For example, U.S. Pat. No. 7,157,872 discloses a ceiling fan with an outer rotor type BLDC motor. The BLDC motor comprises a controller, a stator, and a rotor, wherein the controller is connected to a group of magnetism sensors corresponding in position to induction magnets disposed on the periphery outer surface of the rotor, so as to indirectly detect polarity of the permanent magnets of the rotor through the induction magnets and thereby drive the rotor to continuously rotate in the same direction. However, with the controller being above the motor housing (that is, outside the motor housing) and additional induction magnets being provided for the motor housing so as for the sensors to detect variation of magnetic field, conduction lines have to extend from inside of the motor housing to the outside of the motor housing for connecting the controller, which inevitably complicates the whole structure and increases the overall size and the material cost. The induction magnets also complicate the whole structure and increase the overall size. 
         [0009]    Accordingly, Taiwan Patent No. M315782 and No. M320603 propose technique whereby a sensing element is fixed in position to a fan, wherein a motor comprises a stator formed from a shaft and silicon steel sheets, a rotor, a sensing element, and a circuit board. The silicon steel sheets have a predetermined receiving slot for receiving and positioning the sensing element. However, with both the circuit board and the sensing element being positioned on the periphery of the stator according to the technique, a dispensing process is required to prevent detachment of the sensing element from the circuit board, which accordingly complicates the fabrication process. 
         [0010]    Therefore, there is a need to provide a motor structure and a fan to overcome the above-described drawbacks. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, an objective of the present invention to provide a motor structure and a fan which are structurally simple and are easy to fabricate. 
         [0012]    Another objective of the present invention is to provide a motor structure and a fan which are downsized by using less components. 
         [0013]    A further objective of the present invention is to provide a motor structure and a fan so as to reduce the material cost. 
         [0014]    In order to attain the above and other objectives, the present invention provides a motor structure, which comprises: a shaft; a motor control panel having a first fastening portion and engageable with the shaft; a stator having a second fastening portion corresponding in position to the first fastening portion, wherein the second fastening portion is coupled with the first fastening portion so as to fasten the motor control panel to the stator; a rotor corresponding in position to the stator and pivotally connected to the shaft; and a motor housing pivotally connected to the shaft, enclosing the shaft, the motor control panel, the stator, and the rotor. 
         [0015]    To attain the above and other objectives, the present invention further provides a fan comprising a fan blade element with a plurality of blades and a motor structure, wherein the motor structure comprises: a shaft; a motor control panel having a first fastening portion and configured for connection with a power source; a stator engageable with the shaft and comprising a base body engageable with the shaft and having a plurality of excitation units and a fastening base disposed on one side of the base body facing the motor control panel, the fastening base having a second fastening portion corresponding in position to the first fastening portion for coupling with the second fastening portion so as to fasten the motor control panel to the stator; a rotor corresponding in position to the stator and pivotally connected to the shaft and connected to the fan blade element, the rotor having a predetermined number of magnet units corresponding in number to the excitation units; and a motor housing pivotally connected to the shaft, enclosing the shaft, the motor control panel, the stator, and the rotor. Therein, when the motor control panel is connected to a power source, electric power is distributed to each of the excitation units so as to generate an induced magnetic field for creating attraction and repulsion between the excitation units and the magnet units, and in consequence the rotor drives the fan blade element to rotate. 
         [0016]    In the present invention, a first fastening portion is disposed on the motor control panel and a second fastening portion corresponding in position to the first fastening portion is disposed on the stator such that the motor control panel can be fastened to the stator through coupling of the first and second fastening portions. Accordingly, not only the motor control panel is disposed inside the motor structure, but it is not necessary to provide a receiving slot on silicon steel sheets or perform a dispensing process as in the prior art. Therefore, the motor structure and the fan using the motor structure of the present invention are simple and easy to fabricate. Further, the induction magnets as in the prior art are not needed in the present invention and the conductive lines of the present invention do not have to extend to the outside of the motor housing for electrically connecting a controller as in the prior art, thereby reducing the overall size of the motor structure and saving the material cost. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is an exploded view of a motor structure according to the present invention; 
           [0018]      FIG. 2  is an assembly view of the motor structure according to the present invention; 
           [0019]      FIG. 3  is a sectional view of the motor structure according to the present invention; 
           [0020]      FIG. 4  is an exploded view of a fan with the motor structure; and 
           [0021]      FIG. 5  is an exploded view of the motor structure, viewed from another angle. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0022]    The following illustrative embodiments are provided to illustrate the disclosure of the present invention, these and other advantages and effects can be apparent to those skilled in the art after reading the disclosure of this specification. 
         [0023]      FIGS. 1 to 5  are different views illustrating a motor structure according to the present invention. As shown in the drawings, the motor structure  100  of the present invention comprises a motor control panel  10 , a stator  20 , a rotor  30 , a shaft  22 , bearings  26 , a shield plate  60 , and a motor housing. The motor structure  100  is an outer-rotor type brushless DC motor (BLDC). The rotor  30  rotates around the stator  20  so as to cause the fan  40  to rotate around the stator  20 , as shown in  FIG. 4 . The fan  40  may be a ceiling fan or other fan devices. The components of the motor structure are detailed as follows. 
         [0024]    The motor control panel  10  comprises a first fastening portion  11  and a shaft hole  12  for receiving the shaft  22  therethrough. The stator  20  engages the shaft  22 . The stator  20  comprises: a base body  200 , a fastening base  21  disposed on one side of the base body  200  facing the motor control panel  10  (as shown in  FIG. 5 ), and a plurality of excitation units  25 . The base body  200  is formed by stacking and series-connecting a plurality of metal sheets such as silicon steel sheets. The fastening base  21  is a metal base disposed on one side of the base body  200  facing the motor control panel  10 . The fastening base  21  has a second fastening portion  23  corresponding in position to the first fastening portion  11 . Through coupling of the first fastening portion  11  and the second fastening portion  23 , the motor control panel  10  is firmly fastened to the base body  200  of the stator  20 . The rotor  30  corresponds in position to the stator  20  and is pivotally connected to the shaft  22 . In particular, the first fastening portion  11  is a hole, and the second fastening portion  23  is a stud or has a block-like structure, such that the motor control panel  10  can be fastened to the stator  20  through screwing of the stud (the second fastening portion  23 ) into the hole (the first fastening portion  11 ). Of course, the numbers, positions and sizes of the holes and the studs are not limited to the present embodiment. In other embodiments, the first fastening portion  11  is a stud, and the second fastening portion  23  is a hole. In addition, other structures may be applied to couple the first fastening portion  11  and the second fastening portion  23  together. 
         [0025]    A predetermined number of excitation units  25  are disposed around the base body  200  of the stator  20  and electrically connected to the motor control panel  10 . The rotor  30  has a predetermined number of magnet units  34  corresponding to the predetermined number of excitation units  25 . 
         [0026]    The motor housing comprises a first housing  71  and a second housing  72 . The first housing  71  and the second housing  72  are pivotally connected to the shaft  22  and enclose the shaft  22 , the motor control panel  10 , the stator  20 , and the rotor  30 . The stator  20  is pivotally connected to the shaft  22  through two bearings  26  disposed at two ends of the shaft  22 , and the two bearings  26  are further disposed in the shaft holes of the first housing  71  and the second housing  72  respectively. The rotor  30  further comprises a fastening frame  33  disposed inside the first housing  71  and the second housing  72  and has an inner wall  331  and an outer wall  332 , wherein the inner wall  331  encircles the periphery of the base body  200  of the stator  20  and the predetermined number of magnet units  34  are evenly disposed on the outer wall  332 . Thus, the magnet units  34  and the excitation units  25  are spaced from each other. Further, the first housing  71  has an engaging slot  711  for receiving and engaging with one end of each of the magnet units  34 . Upon connection with a power source, the motor control panel  10  distributes electric power to each of the excitation units  25 , allowing the excitation units  25  to generate an induced magnetic field for creating attraction and repulsion relative to the magnet units  34 , thereby driving the rotor  30  to rotate. 
         [0027]    In the above-described embodiment, the excitation units  25  are coils windingly disposed in a ring-shaped slot (not shown) of the base body  200 . The magnet units  34  comprise permanent magnets. The numbers, positions and sizes of the magnet units  34  are not limited. But in principle, the magnet units  34  are disposed in slots  333  around the fastening frame  33  and arranged with magnetic poles of opposite polarity located adjacent one another and extending to positions capable of inducting with the excitation units  25 . It is well known in the art that the excitation coils, the permanent magnets, and the stacked and series-connected silicon steel sheets together form the base body  200  of the stator  20 ; hence, detailed description thereof is omitted herein. 
         [0028]      FIG. 4  shows a fan with the motor structure according to the present invention. As shown in the drawing, the fan  40  of the present invention is a ceiling fan, which comprises: a fan blade element  41  with a plurality of blades  42 , and a motor structure  100 . The motor structure  100  comprises the motor control panel  10 , the stator  20 , the rotor  30 , the shaft  22 , the bearings  26 , the shield plate  60  and the motor housing  70  as shown in  FIG. 3 . The fan blade element  41  is disposed on the first housing  71  of the motor structure. The fan blade element concentrically corresponds in position to the stator  20  and is pivotally connected to the shaft  22 . Since the predetermined number of excitation units  25  are disposed around the stator  20  and electrically connected to the motor control panel  10  and the predetermined number of magnet unit  34  are disposed on the rotor  30  corresponding in position to the excitation units  25 , when the motor control panel  10  is connected to the power source, electric power is distributed to each of the excitation units  25  so as to generate an induced magnetic field creating attraction and repulsion between the excitation units  25  and the magnet units  34 , thereby causing the rotor  30  to rotate along with the first housing  71  and the fan blade element  41  disposed on the first housing  71 . Since the essential features of the motor structure of the present embodiment are similar to the above-described embodiment, detailed description thereof is omitted herein. 
         [0029]      FIG. 5  shows the motor structure viewed from another angle. As shown in the drawing, a sensor element  50  is further disposed on the motor control panel  10 , which can be such as a Hall element for detecting direction of the magnetic field so as to determine polarity and position of the rotor  30 . It should be noted that the position of the sensor element  50  on the motor control panel  10  is not limited to the present embodiment, but the sensor element  50  should be disposed at a non-shielding area capable of sensing the magnet units  34 . That is, sizes, shapes and positions of the magnet units  34  should be designed such that the magnet units  34  can be sensed by the sensor element. Compared with the prior art, since the sensor element  50  is disposed on the motor control panel  10  in the present invention instead of the fastening base  21  (made from silicon steel sheets), the present invention doesn&#39;t need dispensing process, simplifies the whole structure, and facilitates the assembling process. In addition, since the motor structure  100  comprises a shield plate  60  disposed between the motor control panel  10  and the stator  20  so as to shield magnetic fields generated by the excitation units  25  and isolate high voltage, better electrical performance can be achieved. 
         [0030]    Therefore, according to the present invention, a first fastening portion is disposed on the motor control panel and a second fastening portion corresponding in position to the first fastening portion is disposed on the stator such that the motor control panel can be fastened to the stator through coupling of the first and second fastening portions. Accordingly, not only the motor control panel is disposed inside the motor structure, but also the needs of a receiving slot disposed on silicon steel sheets and a dispensing process as in the prior art are eliminated. Therefore, the motor structure and the fan using the motor structure of the present invention are simple and easy to fabricate. Further, the induction magnets as in the prior art are not needed in the present invention and the conductive lines of the present invention do not need to extend to the outside of the motor housing for electrically connecting a controller as in the prior art, thereby reducing the overall size of the motor structure and saving the material cost. Furthermore, the shield plate disposed between the motor control plate and the stator provides better electrical performance. Moreover, by disposing the sensor element on the motor control panel instead of the base body of the stator, the whole structure is simplified and the assembling process is facilitated. Therefore, the motor structure and the fan with the motor structure of the present invention overcome the conventional drawbacks and have high industrial application value. 
         [0031]    The above-described descriptions of the detailed embodiments are only to illustrate the preferred implementation according to the present invention, and it is not to limit the scope of the present invention, Accordingly, all modifications and variations completed by those with ordinary skill in the art should fall within the scope of present invention defined by the appended claims.