Patent Publication Number: US-11387703-B2

Title: Stator of a waterproof motor and method for manufacturing the same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional application of U.S. patent application Ser. No. 16/217,245 filed on Dec. 12, 2018. The application claims the benefit of Taiwan application serial No. 107104551, filed on Feb. 8, 2018, and the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a component of a motor and a method for manufacturing the component of the motor and, more particularly, to a stator of a waterproof motor and a method for manufacturing the stator of the waterproof motor. 
     2. Description of the Related Art 
       FIG. 1  shows a stator  9  of a waterproof motor manufactured by a conventional manufacturing method. The conventional manufacturing method includes forming a stator assembly  91  in a mold, filling the space between the stator assembly  91  and the cavity wall of the mold with a filler, and removing the mold to obtain the stator  9  of the waterproof motor. The stator  9  includes a protective layer  92 . An embodiment of such a method for manufacturing a stator of a waterproof motor is disclosed in U.S. Patent Publication No. 2007/0085426 (Taiwan Patent No. 1344253). 
     Although the conventional manufacturing method can form the protective layer  92  in a single process, the electronic components of the stator assembly  91  are often damaged by the large injection pressure of the thermosetting material which forms the protective layer  92 . As a result, it is difficult to increase the yield rate. In another case where the waterproof glue is used as the material of the protective layer  92 , it takes dozens of hours to cure the waterproof glue. This requires an extra process of baking the waterproof glue. Disadvantageously, the yield rate is low and the energy consumption is high. 
     In light of this, it is necessary to improve the conventional method for manufacturing a stator of a waterproof motor. 
     SUMMARY OF THE INVENTION 
     It is therefore the objective of this invention to provide a method for manufacturing a stator of a waterproof motor which can lower the damage to the components and reduces the amount of the waterproof glue used. 
     In an aspect, a method for manufacturing a stator of a waterproof motor includes disposing a first assembly in a mold where the first assembly includes a coil unit wound around an iron core assembly, and filling the mold with a thermosetting plastic which forms a housing after curing. The housing houses the coil unit and the iron core assembly. A recess is formed at one end of the housing. The method further includes disposing a second assembly in the recess of the housing where the second assembly includes a circuit unit, and filling the recess of the housing with a waterproof glue which envelopes the circuit unit after curing. According to the above, the stator of the waterproof motor is formed. 
     In an example, the method for manufacturing the stator of the waterproof motor further includes coupling the iron core assembly with an outer periphery of a shaft tube of the first assembly before forming the housing. The housing is coupled with the outer periphery of the shaft tube. One end of the shaft tube is not enveloped by the housing and extends into the recess of the housing. Thus, it is ensured that the liquid will not be able to intrude into the gap between the shaft tube and the housing, improving the waterproof effect of the motor. 
     In the example, disposing the second assembly includes connecting a circuit connector of the circuit unit to a coil connector of the coil unit which is exposed to the recess of the housing, and filling the recess includes enveloping the coil connector of the coil unit and the circuit unit with the waterproof glue. Thus, the waterproof effect and the convenience in assembly are improved. 
     In the example, the coil unit includes a wire wound around a post of the iron core assembly. A free end of the post extends out of the housing and is exposed to the recess after forming the housing. Disposing the second assembly includes disposing a circuit board of the circuit unit in the recess of the housing and engaging the circuit board of the circuit unit with the post of the iron core assembly, and filling the recess includes enveloping the post and the circuit board with the waterproof glue. Thus, the waterproof effect and the convenience in assembly are improved. 
     In another aspect, a method for manufacturing a stator of a waterproof motor includes disposing a first assembly in a mold where the first assembly includes a coil unit wound around an iron core assembly, positioning a second assembly in an electric box which includes a circuit unit, and filling the mold with a thermosetting plastic which forms a housing after curing. The housing houses the coil unit and the iron core assembly. A recess is formed at one end of the housing. A retaining ring forms at a circumferential edge of the recess. The method further includes filling the electric box with a waterproof glue which envelopes the circuit unit after curing, and engaging the electric box with the housing to press the retaining ring against the waterproof glue. According to the above, the stator of the waterproof motor is formed. 
     In an example, engaging the electric box includes connecting a circuit connector of the circuit unit, which is exposed out of the waterproof glue, to a coil connector of the coil unit which is exposed out of the housing before pressing the retaining ring against the waterproof glue. Thus, the waterproof effect and the convenience in assembly are improved. 
     In the example, the thermosetting plastic is bulk molding compound (BMC) and the waterproof glue is polyurethane (PU) or silicone glue. Thus, the quality of the waterproof motor is improved. 
     In a further aspect, a stator of a waterproof motor includes a first assembly having a coil unit wound around an iron core assembly, a housing made of thermosetting plastic and enveloping the coil unit and the iron core assembly where a recess is formed at one end of the housing, and a second assembly disposed in the recess of the housing and including a circuit unit. The recess is filled with a waterproof glue which envelops the circuit unit. 
     In an example, the first assembly includes a shaft tube and the iron core assembly is coupled with an outer periphery of the shaft tube. The housing is coupled with the outer periphery of the shaft tube. One end of the shaft tube is not enveloped by the housing and extends into the recess. Thus, it is ensured that the liquid will not be able to intrude into the gap between the shaft tube and the housing, improving the waterproof effect of the motor. 
     In the example, the coil unit includes a coil connector exposed to the recess of the housing and connected to a circuit connector of the circuit unit, and the waterproof glue envelopes the coil connector of the coil unit and the circuit unit. Thus, the waterproof effect and the convenience in assembly are improved. 
     In the example, the second assembly includes a support coupled with the shaft tube and located in the recess of the housing, and the circuit unit includes a circuit board coupled with the support. Thus, the circuit board can be securely positioned in the recess of the housing. 
     In the example, a shoulder portion is provided on the outer periphery of the shaft tube. The housing includes an axial extension portion abutting the outer periphery of the shaft tube and extending into the recess of the housing. A free end of the axial extension portion abuts the shoulder portion. The support is connected to the axial extension portion Thus, the reliability in engagement between the housing and the shaft tube is improved. 
     In the example, the iron core assembly includes a post having a free end extending out of the housing and exposed to the recess. The coil unit includes a wire wound around the post of the iron core assembly. The circuit unit includes a circuit board located in the recess of the housing and engaged with the post of the iron core assembly. The waterproof glue envelopes the post and the circuit board. Thus, the convenience in assembly is improved. 
     In still a further aspect, a stator of a waterproof motor includes a first assembly having a coil unit wound around an iron core assembly, a second assembly including a circuit unit, and a housing made of thermosetting plastic and enveloping the coil unit and the iron core assembly. A recess is formed at one end of the housing. A retaining ring forms at a circumferential edge of the recess. The stator of the waterproof motor further includes an electric box receiving the second assembly and filled with a waterproof glue to envelope the circuit unit with the waterproof glue. The electric box and the housing are coupled with each other. The retaining ring is pressed against the waterproof glue. 
     In an example, the coil unit includes a coil connector exposed out of the housing and connected to a circuit connector of the circuit unit which is exposed out of the waterproof glue, and the coil connector of the coil unit is connected to the circuit connector of the circuit unit in an inner space delimited by an inner periphery of the retaining ring. Thus, the waterproof effect and the convenience in assembly are improved. 
     In the example, a rotor space is formed at a center of the housing, and the housing includes a shaft-coupling portion located in the rotor space. Thus, the convenience in assembly is improved. 
     In the example, the housing includes a plurality of screwing portions surrounding the retaining ring and screwed to a plurality of screwing portions of the electric box. Thus, the waterproof effect is improved. 
     In the example, the plurality of screwing portions of the housing is located outside the waterproof glue. Thus, it can prevent the fasteners from damaging the waterproof glue. 
     In the example, a wire groove is provided surrounding an outer periphery of the retaining ring. The wire groove is not intercommunicating with an inner space delimited by an inner periphery of the retaining ring. The circuit unit includes a wire connected to a circuit board. A portion of the wire that is connected to the circuit board is enveloped by the waterproof glue. The wire is partially exposed out of the waterproof glue and extends out of the housing through the wire groove. Thus, the waterproof glue can prevent the wire from breaking somewhere around the circuit board and prevent the liquid from permeating into the inner space of the retaining ring when the wire is being pulled out of the housing. As a result, the convenience in connecting the wire to an external power supply and the waterproof effect are improved. 
     Based on the above, the stator of the waterproof motor and the method for manufacturing the same can significantly reduce the amount of the waterproof glue used. Thus, the yield rate and quality of the product as well as the production efficiency are improved while the manufacturing cost is reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a cross sectional view of a stator of a conventional waterproof motor. 
         FIG. 2  is a cross sectional view of a first assembly of a stator of a waterproof motor according to a first embodiment of the invention. 
         FIG. 3  is a cross sectional view of a housing and the first assembly of  FIG. 2 . 
         FIG. 4  is a cross sectional view of a second assembly and the housing and the first assembly of  FIG. 3 . 
         FIG. 5  is a cross sectional view of the stator of the first embodiment filled with a waterproof glue. 
         FIG. 6  is a cross sectional view of the stator of the first embodiment which is coupled with a rotor. 
         FIG. 7  is a cross sectional view of a stator of a waterproof motor according to a second embodiment of the invention. 
         FIG. 8  is a cross sectional view of a first assembly and an electric box of a stator of a waterproof motor according to a third embodiment of the invention. 
         FIG. 9  is a cross sectional view of the stator of the waterproof motor of the third embodiment where the electric box is filled with a waterproof glue and a housing is formed. 
         FIG. 10  is a longitudinal cross sectional view of the housing and the first assembly of the stator taken along line  10 - 10  of  FIG. 9 . 
         FIG. 11  is a top view of a circuit unit and the electric box of the stator taken along line  11 - 11  of  FIG. 9 . 
         FIG. 12  is an assembled, cross sectional view of the stator of the waterproof motor according to the third embodiment of the invention. 
         FIG. 13  is a cross sectional view of the stator of the third embodiment which is coupled with a rotor. 
     
    
    
     In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “third”, “fourth”, “inner”, “outer”, “top”, “bottom”, “front”, “rear” and similar terms are used hereinafter, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A method for manufacturing a stator of a waterproof motor according to a first embodiment of the invention includes the steps described as follows. 
     Referring to  FIG. 2 , the method for manufacturing the stator of the waterproof motor includes disposing a first assembly  1  in a mold (not shown). The first assembly  1  at least includes a coil unit  11  wound around an iron core assembly  12 . In this embodiment, the iron core assembly  12  includes a plurality of silicon steel plates  121  and an insulating sleeve unit  122 . The silicon steel plates  121  are stacked together and are clamped by the insulating sleeve unit  122 . The coil unit  11  is radially wound around the insulating sleeve unit  122 . 
     Referring to  FIG. 3 , the method for manufacturing the stator of the waterproof motor further includes filling the mold with a thermosetting plastic. The thermosetting plastic forms a housing  2  which envelopes the coil unit  11  and the iron core assembly  12  after curing. A recess  21  is formed at one end of the housing  2 . The thermosetting plastic may be epoxy resin, Preferably, the thermosetting plastic is thermosetting plastic formed by injecting molding, such as bulk molding compound (BMC). The bulk molding compound is lightweight and has a high strength and a low shrinkage rate. The bulk molding compound is highly temperature-resistant and moisture-resistant. The bulk molding compound permits the mold removal at an angle of 0 degree. This improves not only the formation rate and formation efficiency of the housing  2  but also the quality of the produced waterproof motor. 
     Referring to both  FIGS. 2 and 3  again, it is worth mentioning that the first assembly  1  in this embodiment preferably includes a shaft tube  13 . Before the formation of the housing  2 , the iron core assembly  12  can be fixed to the outer periphery of the shaft tube  13  to couple the housing  2  to the outer periphery of the shaft tube  13  after the housing  2  cures. At the same time, one end of the shaft tube  13  is not enveloped by the housing  2  and protrudes into the recess  21 . In this arrangement, the watertight effect between the shaft tube  13  and the housing  2  is improved, ensuring that the liquid will not be able to intrude into the gap between the shaft tube  13  and the housing  2 . Furthermore, a shoulder portion  131  may be provided on the outer periphery of the shaft tube  13 . Thus, during the formation of the housing  2 , the housing  2  can form an axial extension portion  22  abutting the outer periphery of the shaft tube  13  and extending into the recess  21 . A free end of the axial extension portion  22  abuts the shoulder portion  131  of the shaft tube  13 . As a result, the convenience in positioning the shaft tube  13  in the mold is improved, thereby forming the housing  2 . In addition, the arrangement of the axial extension portion  22  increases the contact area between the housing  2  and the shaft tube  13 , thus providing a more reliable engagement effect between the housing  2  and the shaft tube  13 . 
     Referring to  FIG. 4 , the method further includes positioning a second assembly  3  in the recess  21  of the housing  2 . The second assembly  3  includes at least a circuit unit  31 , The circuit unit  31  may include a circuit board  311  and a plurality of electronic components  312  mounted on the circuit board  311 . In this embodiment, the second assembly  3  may further include a support  32 . After the formation of the housing  2 , the support  32  can be coupled with the axial extension portion  22  of the housing  2 , such that the support  32  is fixed to the outer periphery of the shaft tube  13  and is located in the recess  21  of the housing  2 . Then, the circuit board  311  of the circuit unit  31  is coupled with the support  32  such that the circuit board  311  can be stably positioned in the recess  21 . In another embodiment, the support  32  can be formed at the time the housing  2  is formed. In other words, the support  32  and the housing  2  are integrally formed with each other. 
     Referring to  FIG. 5 , the method further includes filling the recess  21  with a waterproof glue  4  to envelope the circuit unit  31 , thus obtaining the stator of the waterproof motor of the first embodiment of the invention. The waterproof glue  4  may be polyurethane (PU) or silicone glue. 
     Referring to  FIGS. 4 and 5  again, the coil unit  11  of the first assembly  1  may include a coil connector  111 . During the formation of the housing  2 , the housing  2  may not envelope the coil connector  111  such that the coil connector  111  is exposed to the recess  21 . In this regard, the circuit unit  31  includes a circuit connector  313  connected to the circuit board  311 . Therefore, when the second assembly  3  is positioned in the recess  21  the coil connector  111  of the coil unit  11  can be connected to the circuit connector  313  of the circuit unit  31 . Then, the recess  21  is filled with the waterproof glue  4  to envelope the coil connector  111  of the coil unit  11  and the entire circuit unit  31 , In another embodiment, the wire of the coil unit  11  can be directly welded to the circuit board  311  to electrically connect the coil unit  11  to the circuit board  311 . 
     Referring to  FIG. 5 , based on the above process, the method for manufacturing the stator of the waterproof motor according to the first embodiment of the invention can achieve at least the advantages of improved yield rate, improved quality, improved production efficiency and higher production capacity, and reduced manufacturing cost. 
     With respect to the first advantage (improved yield rate), the manufacturing method of the invention envelopes the fragile parts of the motor with the waterproof glue  4  that has a relatively smaller filling pressure, and envelopes the strong parts of the motor with a thermosetting plastic that has a relatively larger injection pressure. In this manner, there are hardly components damaged during the formation of the waterproof structure, significantly improving the yield rate of the product. 
     With respect to the second advantage (improved quality), under the high yield rate stated above, the manufacturing method of the invention permits the thermosetting plastic to fill the tiny gaps inside the mold based on the high flowability of the thermosetting plastic. Thus, the thermosetting plastic can completely envelope those parts of the first assembly  1  which requires sealing, thereby providing the first assembly  1  with excellent insulating function and waterproof function. As a result, higher yield rate and product quality are attained. 
     With respect to the third advantage (improved production efficiency and higher production capacity), the majority part of the stator of the waterproof motor can be enveloped by the thermosetting plastic while the minority part of the stator which is more easily broken is enveloped by the waterproof glue  4 . Thus, the amount of the waterproof glue  4  as required is significantly reduced. Following the injection molding, the bulk molding compound (BMC) can cure almost as soon as the mold is removed, thereby reducing the amount of the waterproof glue  4  used and significantly shortening the time it takes for the waterproof glue  4  to cure, Advantageously, the method for manufacturing the stator of the waterproof motor according to the invention can significantly improve the production efficiency and the production capacity. 
     With respect to the fourth advantage (reduced manufacturing cost), the method for manufacturing the stator of the waterproof motor according to the invention can significantly reduce the amount of the waterproof glue  4  used and reduce the energy required to bake the waterproof glue  4 . As a result, the manufacturing cost is lowered. It is noted that the method according to the invention no longer requires a fixture that is needed for filling purpose of the waterproof glue  4  as the recess  21  is formed during the formation of the housing  2  for filling purpose of the waterproof glue  4 . Thus, the expenses resulting from bulk purchase, maintenance and warehousing of the fixtures are not incurred. 
     Referring to  FIG. 5 , the stator of the waterproof motor according to the first embodiment of the invention can be obtained based on the above manufacturing method. The stator includes a first assembly  1 , a housing  2 , a second assembly  3  and a waterproof glue  4 . The first assembly  1  at least includes a coil unit  11  wound around the iron core assembly  12 . The housing  2  envelops the coil unit  11  and the iron core assembly  12 . A recess  21  is formed at one end of the housing  2 . The second assembly  3  is positioned in the recess  21 . The second assembly  3  includes at least a circuit unit  31 . The waterproof glue  4  fills the recess  21  and envelops the circuit unit  31 . 
     The first assembly  1  preferably further includes a shaft tube  13 . The iron core assembly  12  is fixed to the outer periphery of the shaft tube  13 . The housing  2  is coupled with the outer periphery of the shaft tube  13 . One end of the shaft tube  13  is not enveloped by the housing  2  and extends into the recess  21 . In this embodiment, the second assembly  3  includes a support  32  fit around the shaft tube  13  and located in the recess  21  of the housing  2 . The circuit unit  31  includes a circuit board  311  coupled with the support  32  such that the circuit board  311  can be stably positioned in the recess  21 . A shoulder portion  131  is provided on the outer periphery of the shaft tube  13 . The housing  2  includes an axial extension portion  22  abutting the outer periphery of the shaft tube  13  and extending into the recess  21  of the housing  2 . A free end of the axial extension portion  22  abuts the shoulder portion  131 . The support  32  is integrally formed with or connected to the axial extension portion  22 . The coil unit  11  includes a coil connector  111  exposed to the recess  21  of the housing  2  and connected to a circuit connector  313  of the circuit unit  31 . The waterproof glue  4  envelops the coil connector  111  of the coil unit  11  and the circuit unit  31 . 
     Referring to  FIG. 6 , a rotor  8  includes a shaft  81  rotatably coupled with the shaft tube  13  of the stator of the waterproof motor according to the first embodiment of the invention. In this regard, a magnet  82  faces the iron core assembly  12 . After the stator is electrified to generate a magnetic field, the rotor  8  is driven to rotate. Besides, a seat B includes a retaining ring R. The seat B is coupled with the shaft tube  13  while the retaining ring R is pressed against the waterproof glue  4 . 
       FIG. 7  shows a stator of a waterproof motor as manufactured by a manufacturing method according to a second embodiment of the invention. The stator of the waterproof motor in  FIG. 7  is substantially the same as that of the first embodiment except for the manner the second assembly  3  is positioned in the recess  21  of the housing  2 . 
     Specifically, the iron core assembly  12  of the first assembly  1  in this embodiment includes a post  123 . The post  123  is an electrically conductive post on the insulating sleeve unit  122 . A wire  112  of the coil unit  11  is wound around the coil unit  11 . After the housing  2  is shaped, the portion of the post  123  that is wound with the wire  112  is preferably enveloped by the housing  2  while the free end of the post  123  extends out of the housing  2  and is exposed to the recess  21 . After the second assembly  3  is disposed in the recess  21 , the post  123  extends through and couples with the circuit board  311  of the circuit unit  31  to simplify the assembly of the second assembly  3 . Then, the recess  21  is filled with the waterproof glue  4  to envelop the post  123  and the circuit unit  31  in the waterproof glue  4 . In this manner, the stator of the waterproof motor according to the second embodiment of the invention can be obtained and can possess the same advantages as the manufacturing method of the first embodiment of the invention. 
     A method for manufacturing a stator of a waterproof motor according to a third embodiment of the invention includes the steps described as follows. 
     Referring to  FIG. 8 , the method for manufacturing the stator of the waterproof motor includes disposing a first assembly  1  in a mold (not shown). The first assembly  1  at least includes a coil unit  11  wound around an iron core assembly  12 . In this embodiment, the iron core assembly  12  includes a plurality of silicon steel plates  121  and an insulating sleeve unit  122  (including two insulating sleeves). The silicon steel plates  121  are stacked together and are clamped by the insulating sleeve unit  122 . The coil unit  11  is radially wound around the insulating sleeve unit  122 . 
     Besides, the second assembly  3  is positioned in an electric box  5 . The electric box  5  includes at least a circuit unit  31  having a circuit board  311  and a plurality of electronic components  312  mounted on the circuit board  311 . 
     Referring to  FIG. 9 , the mold is filled with the thermosetting plastic which forms a housing  6  after curing. The coil unit  11  and the iron core assembly  12  are enveloped by the housing  6 . A recess  61  is formed at one end of the housing  6 . A retaining ring  62  forms near a circumferential edge of the recess  61 . The thermosetting plastic may be epoxy, or preferably be thermosetting plastic formed by injection molding such as bulk molding compound (BMC). 
     The electric box  5  is filled with the waterproof glue  7  to envelop the circuit unit  31  in the waterproof glue  7  (in a manner where at least the electrically conductive parts of the circuit unit  31  are enveloped by the waterproof glue  7 ). The waterproof glue  7  may be polyurethane (PU) or silicone glue. 
     Referring to  FIG. 12 , the electric box  5  and the housing  6  are coupled with each other such that the retaining ring  62  is pressed against the waterproof glue  7 . Accordingly, the stator of the waterproof motor according to the third embodiment of the invention is obtained. When the retaining ring  62  is pressed against the waterproof glue  7 , the waterproof glue  7  can deform under the force to close up the opening of the retaining ring  62 . This ensures that the liquid will not intrude into the inner space delimited by the inner periphery of the retaining ring  62 . 
     Referring to  FIGS. 9 and 12  again, it is noted that the coil unit  11  of the first assembly  1  includes a coil connector  111 , which is exposed out of the housing  6  after the formation of the housing  6 . The circuit unit  31  includes a circuit connector  313  exposed out of the waterproof glue  7 . In this arrangement, during the assembly of the electric box  5  and the housing  6 , the circuit connector  313  of the circuit unit  31  can be connected to the coil connector  111  of the coil unit  11  and then the retaining ring  62  is pressed against the waterproof glue  7 . 
     Based on the above steps, the method for manufacturing the stator of the waterproof motor according to the third embodiment of the invention can achieve the same advantage as the first embodiment. It is noted that the waterproof glue  7  is filled into the electric box  5  such that it will not incur the costs of purchase, maintenance and warehousing of the fixtures required for filling purposes of the waterproof glue  7 , Moreover, the retaining ring  62  can be formed during the formation of the housing  6 , thus omitting the use of a washer (such as an O-ring) during the assembly of the electric box  5  and the housing  6 . In this arrangement, it can be ensured that the liquid will not intrude into the inner space of the waterproof motor, simplifying the structure and improving the efficiency in assembly of the waterproof motor. 
     Referring to  FIG. 12 , based on the manufacturing method according to the third embodiment of the invention, the stator of the waterproof motor of the third embodiment can be obtained. The stator includes a first assembly  1 , a second assembly  3 , a housing  6 , an electric box  5  and a waterproof glue  7 . The first assembly  1  at least includes a coil unit  11  wound around an iron core assembly  12 . The second assembly  3  includes at least a circuit unit  31 , The housing  6  is made of thermosetting plastic and envelops the coil unit  11  and the iron core assembly  12 . A recess  61  is formed at one end of the housing  6 . A retaining ring  62  forms at a circumferential edge of the recess  61 . The second assembly  3  is disposed in the electric box  5 . The waterproof glue  7  fills the inner space of the electric box  5  to envelope the circuit unit  31  (in a manner where at least the electrically conductive parts of the circuit unit  31  are enveloped by the waterproof glue  7 ). The electric box  5  is coupled with the housing  6  while the retaining ring  62  of the housing  6  is pressed against the waterproof glue  7 . 
     The coil unit  11  includes a coil connector  111  exposed out of the housing  6 . The circuit unit  31  includes a circuit connector  313  exposed out of the waterproof glue  7 . The coil connector  111  of the coil unit  11  is connected to the circuit connector  313  of the circuit unit  31  in the inner space delimited by the inner periphery of the retaining ring  62 . A rotor space  63  is formed at the center of the housing  6 . The housing  6  further includes a shaft-coupling portion  64  located in the rotor space  63 , Accordingly, referring to  FIG. 13 , a rotor  8 ′ can be rotatably coupled with the shaft-coupling portion  64  via a shaft  81 ′. Therefore, a magnet  82 ′ which surrounds the shaft  81 ′ can be located in the rotor space  63  and is radially aligned with the iron core assembly  12 . In this arrangement, the stator of the waterproof motor is electrified to generate a magnetic field, driving the rotor  8 ′ to rotate. 
     Specifically, referring to  FIGS. 10 and 12 , the electric box  5  includes a plurality of screwing portions  51  and the housing  6  also includes a plurality of screwing portions  65 . A fastener S can be screwed through a corresponding pair of the screwing portions  51  and  65 . As the liquid will inevitably intrude into the inner space of the motor through the screwing portions  51  and  65 , the plurality of screwing portions  65  preferably surrounds the retaining ring  62 . In this arrangement, although the liquid can permeate into the plurality of screwing portions  51  and the plurality of screwing portions  65 , the liquid cannot permeate further into the inner space delimited by the inner periphery of the retaining ring  62  as the retaining ring  62  is pressed against the waterproof glue  7 . Thus, the waterproof effect of the stator of the motor is improved. 
     A wire groove  621  is provided surrounding the outer periphery of the retaining ring  62 . The wire groove  621  is not intercommunicating with the inner periphery of the retaining ring  62 . The circuit unit  31  includes a wire  314  connected to the circuit board  311 . The portion of the wire  314  that is connected to the circuit board  311  is enveloped by the waterproof glue  7 . The wire  314  is partially exposed out of the waterproof glue  7  and extends out of the housing  6  through the wire groove  621 , so as to connect to an external power supply. In this arrangement, the waterproof glue  7  can prevent the wire  314  from breaking somewhere around the circuit board  311  and prevent the liquid from permeating into the inner space of the retaining ring  62  when the wire  314  is being pulled out of the housing  6 . 
     Referring to  FIGS. 11 and 12 , the plurality of screwing portions  51  of the electric box  5  may be outside of the range of the waterproof glue  7 , preventing the fastener S from breaking the waterproof glue  7  which adversely affects the waterproof effect of the stator of the motor. 
     In summary, the stator of the waterproof motor and the method for manufacturing the same can reduce the damage to the electronic components and significantly lowers the amount of the waterproof glue used. Thus, the yield rate and quality of the product as well as the production efficiency are improved while the manufacturing cost is reduced. 
     Although the invention has been described in detail with reference to its presently preferable embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.