Patent Publication Number: US-2016238030-A1

Title: Motor with heat dissipation structure

Description:
(a) TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a motor and, more particularly, to a motor with a heat dissipation structure capable of restraining temperature therein, wherein the motor is provided with a hollow hood at its housing for collecting the air current generated by a cooling fan provided at a rotating shaft of the motor, wherein one portion of the hollow hood is located above at least one upstream through hole of the motor&#39;s housing, so that the air current can quickly enter the housing via the upstream through hole to dissipate heat therein, and thus the performance and service life of the motor can be increased. 
     (b) DESCRIPTION OF THE PRIOR ART 
     Today, motors are widely used in industry for providing mechanical power. When a motor, irrespective of lower or high power, is running, the rotor assembly (including an armature core formed by an iron core wound with enameled wire, a commutator, a brush unit, etc.) and the magnets in the motor&#39;s housing will generate heat and thus cause a temperature rise. In particular, the heat accumulated in the motor&#39;s housing may cause the brush unit to contain more carbon deposits, thus affecting the electrical circuit of the motor. Besides, high temperature resulting from the armature core may reduce the magnetic intensity of the magnets used in the motor. Thus, the performance of the motor will be gradually reduced. 
     Currently, emergency repair kits, which are commonly used in daily life, employ a low-power motor to drive a compressor unit therein for repairing punctured tires. However, in some countries, the Traffic Act stipulates that, when a tire being punctured happens to a vehicle on a highway, the driver should repair the punctured tire within a specified period and should immediately drive away after the repair is completed to prevent rearward bump. Under these circumstances, for completing the repair as soon as possible, the motor of the compressor unit of an emergency repair kit should be operated at a higher speed. However, if the heat accumulated in the motor&#39;s housing cannot be quickly taken away, the performance of the motor will decrease. Even worse, the enameled wire of the armature core will probably be damaged to cause a short circuit, and thus the motor may burn out. 
     For solving this problem, a motor is usually installed with a cooling fan at its output shaft. However, the airflow induced by the cooling fan can only flow along the outer surface of the motor&#39;s housing. Thus, the heat generated by the armature core, especially the enameled wire, in the motor is not easy to be taken away. The problem of a motor being subject to heat accumulation has not yet been overcome. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide a motor with a heat dissipation structure, wherein the housing of the motor is provided with a hollow hood for collecting the air current generated by a cooling fan provided at a rotating shaft of the motor. The housing defines at least one upstream through hole and at least one downstream through hole. The hollow hood is mounted to the housing such that a head portion thereof is located above the upstream through hole. The air current can be effectively collected by the hollow hood to enter the housing via the upstream through hole and finally to go out of the housing via the downstream through hole, so that the heat generated by the rotor assembly in the housing can be quickly taken away. Thus, heat is not easy to accumulate in the housing, maximum power output of the motor can be achieved, and the performance and service life of the motor can be increased. 
     Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a 3-dimensional view of a motor according to one embodiment of the present invention. 
         FIG. 2  shows a 3-dimensional view of the motor, which is viewed from a different angle than  FIG. 1 . 
         FIG. 3  shows a partially exploded view of the motor. 
         FIG. 4  shows a plan view of the motor. 
         FIG. 5  shows a sectional view of the motor taken along line A-A in  FIG. 4 , wherein the air current generated by a cooling fan is demonstrated. 
         FIG. 6  shows a sectional view of the motor taken along line B-B in  FIG. 4 , wherein the air current generated by the cooling fan is demonstrated. 
         FIG. 7  shows a sectional view of the motor taken along line C-C in  FIG. 4 , wherein the air current generated by the cooling fan is demonstrated. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Since motors are commonly used devices, the principles of a motor&#39;s operation are not illustrated in the following paragraphs. However, basic elements of a motor will be described in this specification. Referring to  FIGS. 1 through 7 , a motor according to one embodiment of the present invention is shown, which includes a cylindrical housing  1 , in which a rotor assembly and two opposite magnets  12  are provided. The rotor assembly includes a rotating shaft  16 , an armature core formed by an iron core  171  wound with enameled wire  172 , and a commutator  173 . The two opposite magnets  12  are provided at an inner surface of the cylindrical housing  1 . The housing  1  has a circumferential wall which terminates at a flat closure wall  101  (a front end of the motor). The flat closure wall  101  is provided with a first bearing  11  at its center and defines a plurality of downstream through holes  103  around the first bearing  11 . A first end of the rotating shaft  16  is mounted to the first bearing  11  (see  FIG. 2 ). The circumferential wall of the housing  1  defines a plurality of upstream through holes  10  for allowing outside air to enter the housing  1 . A sleeve  3 , which is made of a magnetically permeable metal, is closely fitted around the cylindrical housing  1 , so as to increase the performance of the motor. 
     A cover  2  is provided with a second bearing  21  at its center and mounted to a rear end of the housing  1  opposite to the flat closure wall  101 . A second end of the rotating shaft  16  of the rotor assembly is mounted at the second bearing  21  (see  FIG. 1 ). A cooling fan  4  is installed to the second end of the rotating shaft  16  of the rotor assembly, near the cover  2 . The cover  2  defines a plurality of air inlets  22 ,  23 , which allow outside air to enter the housing  1  to dissipate heat therein. 
     A primary feature of the present invention is that a hollow hood  5  is provided at a front portion of the cylindrical housing  1  near the cooling fan  4  for collecting the air current generated by the cooling fan  4 . The hollow hood  5  has a neck portion  51 , a head portion  52 , and a gradually enlarged transitional portion between the neck portion  51  and the head portion  52 , wherein the neck portion  51  opens out at a first opening  510  while the head portion  52  opens out at a second opening  520  which is opposite to the first opening  510 . The hollow hood  5  is mounted to the cylindrical housing  1  such that the neck portion  51  is closely fitted around the cylindrical housing  1  while the head portion  52  is located above the through holes  10 , thus defining an annular air-guiding channel  6  therebetween which communicates with the through holes  10 , and forming an intercepting surface  7  at an inner surface of the gradually enlarged transitional portion of the hollowing hood  5 . The hollow hood  5  is a bell-shaped body, so that the annular air-guiding channel  6  has a cross-sectional dimension which increases gradually as extending from the intercepting surface  7  to the second opening  520  of the hollow hood  5 . In this embodiment, as shown in  FIG. 3 , the first opening  510  of the hollow hood  5  is a circular opening, which has a diameter of (Y); the second opening  520  of the hollow hood  5  is a circular opening, which has a diameter of (X); the gradually enlarged transitional portion of the hollow hood  5  generally has an internal diameter of (Z) at its intercepting surface  7 ; wherein the relationship of X&gt;Y and X&gt;Z and Y=Z is fulfilled. The hollow hood  5  can be mounted to the cylindrical housing  1  via the first opening  510 , wherein the neck portion  51  of the hollow hood  5  is closed fitted around the front portion of the cylindrical housing  1 ; the head portion  52  is located above the cylindrical housing  1  and the upstream through holes  10  and thus is not in contact with the cylindrical housing  1 . The annular air-guiding channel  6  is defined between the head portion  52  of the hollow hood  5  and the cylindrical housing  1 , and the through holes  10  are located between the intercepting surface  7  and the second opening  520  of the hollow hood  5 , so that the air current can pass through the annular air-guiding channel  6  and the through holes  10  to enter the cylindrical housing  1  to take away the heat generated therein. The intercepting surface  7  of the hollow hood  5  can intercept the air current entering the annular air-guiding channel  6  to facilitate it to pass through the through holes  10  to enter the housing  1 . 
     In operation, as shown in  FIG. 5 , in addition to some of the air current generated by the cooling fan  4  being able to enter the housing  1  via the air inlets  22 ,  23  defined at the cover  2 , most of the air current generated by the cooling fan  4  can be collected by the hollow hood  5 , wherein the intercepting surface  7  can intercept or block the air current entering the annular air-guiding channel  6 , so that the air current can pass through the upstream through holes  10  to enter the cylindrical housing  1  more easily. After the air current enters the cylindrical housing  1 , the heat generated by the brush unit  192 , the commutator  173  (see  FIG. 6 ), and the iron core  171  wound with the enameled wire  172  (see  FIG. 7 ) can be taken away and finally the air current can flow out of the housing  1  via the downstream through holes  103 , so that heat is not easy to accumulate in the housing  1  and thus the service life of the motor can be increased. In addition, if the diameter of the cooling fan  4  is larger than that of the second opening  520  of the hollow hood  5 , some of the air current generated by the cooling fan  4  may pass over the hollow hood  5  to flow along the outer surface of the circumferential wall of the cylindrical housing  1  and the sleeve  3  to cool down the housing  1  (see  FIG. 5 ). 
     As a summary, the hollow hood  5  of the motor of the present invention can effectively collect the air current generated by the cooling fan  4 , so that the air current can quickly enter the cylindrical housing  1  via the upstream through holes  10  to dissipate the heat generated therein. As such, heat is not easy to accumulate in the housing and thus the performance and service life of the motor can be increased.