Patent Publication Number: US-11664617-B2

Title: Electrical terminal, method for manufacturing elastic terminal, electrical connector and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of Chinese Patent Application No. 202010324765.6, filed on Apr. 22, 2020. 
     FIELD OF THE INVENTION 
     The present invention relates to an electrical terminal and, more particularly, to an electrical terminal having a plurality of elastic sheets. 
     BACKGROUND 
     A socket-type electrical connector is adapted receive an insertion of a pin-type mating terminal. The mating terminal may be inserted into the electrical connector to be electrically connected with an elastic terminal in the electrical connector. The electrical connector has a generally cylindrical outer profile, and is adapted to be fixed and electrically connected onto a circuit board, so as to realize an electrical connection between a wire connected to the mating terminal and the circuit board. 
     During an operation, the mating terminal may float relative to the electrical connector due to an interference of external factors such as a vibration, which may cause an electrical connection between the mating terminal and the electrical connector to fail, and sometimes even damage the mating terminal and/or the electrical connector. The elastic terminal of the existing electrical connector has limited electrical contact portions in number, which may result in large body resistance and a contact resistance of the elastic terminal as well as a relatively large insertion force when inserting the elastic terminal of the mating terminal. 
     SUMMARY 
     An elastic terminal includes a first base having an annular shape and a plurality of elastic sheets extending from the first base in an axial direction. A slit is formed between a pair of adjacent elastic sheets. The plurality of elastic sheets include a plurality of sets of elastic sheets, each elastic sheet of each set of elastic sheets has a plurality of electrical contact portions protruding inwardly radially. The electrical contact portions of one set of elastic sheets are arranged on a same circumference and the electrical contact portions of different sets of elastic sheets are staggered with respect to each other in the axial direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying Figures, of which: 
         FIG.  1    is a perspective view of an electrical connector according to an embodiment; 
         FIG.  2    is a perspective view of the electrical connector of  FIG.  1    connected with a mating terminal; 
         FIG.  3    is an exploded perspective view of the electrical connector of  FIG.  1   ; 
         FIG.  4    is a sectional perspective view of the electrical connector of  FIG.  1   ; 
         FIG.  5    is a perspective view of the electrical connector of  FIG.  1    in a state in which a lower blocking disc of an outer housing is not bent; 
         FIG.  6    is a perspective view of the electrical connector of  FIG.  1    in a state in which the lower blocking disc of an outer housing is bent; 
         FIG.  7    is a perspective view of an elastic terminal according to an embodiment; 
         FIG.  8    is another perspective view of the elastic terminal of  FIG.  7   ; 
         FIG.  9    is a top view of the elastic terminal of  FIG.  7   ; 
         FIG.  10    is a front view of the elastic terminal of  FIG.  7   ; 
         FIG.  11    is an enlarged view of a part A of  FIG.  10   ; 
         FIG.  12    is a plan view of the elastic terminal of  FIG.  7    during manufacture; 
         FIG.  13    is a perspective view of an elastic terminal according to another embodiment; 
         FIG.  14    is a perspective view of an electrical connector according to another embodiment; 
         FIG.  15    is a sectional perspective view of the electrical connector of  FIG.  14   ; 
         FIG.  16    is a perspective view of the electrical connector of  FIG.  14    connected with a mating terminal; 
         FIG.  17    is an exploded perspective view of the electrical connector of  FIG.  14   ; 
         FIG.  18    is a perspective view of the electrical connector of  FIG.  14    in a state in which a lower blocking disc of an outer housing is not bent; 
         FIG.  19    is another perspective view of the electrical connector of  FIG.  14   ; 
         FIG.  20    is a perspective view of an electrical connector according to another embodiment; 
         FIG.  21    is a sectional perspective view of the electrical connector of  FIG.  20   ; 
         FIG.  22    is an exploded perspective view of the electrical connector of  FIG.  21   ; and 
         FIG.  23    is a sectional perspective view of an electrical connector according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     The technical solution of the disclosure will be described hereinafter in further detail with reference to the following embodiments, taken in conjunction with the accompanying drawings. In the description, the same or similar reference numerals indicate the same or similar parts. The description of the embodiments of the disclosure hereinafter with reference to the accompanying drawings is intended to explain the general inventive concept of the disclosure and should not be construed as a limitation on the disclosure. 
     In addition, in the following detailed description, for the sake of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may also be practiced without these specific details. In other instances, well-known structures and devices are illustrated schematically in order to simplify the drawing. 
     As shown in  FIGS.  1  to  3   , in an exemplary embodiment of the disclosure, an electrical connector  100  is adapted to be electrically connected with a plug-type mating terminal  200 , and includes an outer housing  1 , an inner housing  2 , and an elastic terminal  3 . 
     In an exemplary embodiment of the disclosure, as shown in  FIGS.  1  to  4   , the outer housing  1  includes an outer cylinder  11 , and an upper blocking disc  12  and a lower blocking disc  14  radially inwardly extending from both ends of the outer cylinder  11 . The upper blocking disc  12  is formed with an outer through hole  15 . The inner housing  2  includes an inner cylinder  21  and a mounting portion  24  surrounding the inner cylinder  21  and integrally formed around the inner cylinder  21 . The mounting portion  24  is movably mounted in a space defined by the outer cylinder  11 , the upper blocking disc  12 , and the lower blocking disc  14 . As shown in  FIG.  4   , the inner housing  2  is formed with an inner through hole  23 . The elastic terminal  3  is mounted in the inner cylinder  21  and is configured to be electrically connected with the mating terminal  200  inserted into the inner cylinder  21  through the outer through hole  15  of the outer housing  1 . 
     The electrical connector  100  according to an exemplary embodiment of the disclosure further includes an elastic mechanism  4  mounted between the outer housing  1  and the inner housing  2 , as shown in  FIGS.  3  and  4   . The inner housing  2  is movable relative to the outer housing  1  against an elastic force of the elastic mechanism  4 . Since the inner housing  2  is movable relative to the outer housing  1  against the elastic force of the elastic mechanism  4 , the mating terminal  200  mounted in the elastic terminal  3  is allowed to move relative to the outer housing  1  together with the elastic terminal  3  to realize a floating electrical connection between the mating terminal  200  and the electrical connector  100 . 
     As shown in  FIGS.  1  to  6   , in an exemplary embodiment of the disclosure, the lower blocking disc  14  is formed by bending inwardly radially after the inner housing  2  and the elastic mechanism  4  are assembled into the outer housing  1 . In this way, a holding force of the lower blocking disc  14  to the inner housing  2  may be increased, and an overall structure of the electrical connector  100  may be simplified. In addition, the upper blocking disc  12  and the outer cylinder  11  may be manufactured at one time through a stamping process, for example. 
     In an exemplary embodiment of the disclosure, the electrical connector  100  may comprise a circular connector and have a generally cylindrical outer profile. Each of the outer housing  1 , the inner housing  2  and the elastic mechanism  4  is made of a conductive material such as copper, such that the mating terminal  200  is in electrical communication with the outer housing  1 . In this way, the outer housing  1  may be directly electrically connected onto a circuit board  300  to realize an electrical connection between the mating terminal  200  and the circuit board  300 . 
     In an exemplary embodiment of the disclosure, the mounting portion  24  has the same height as that of the inner cylinder  21 . That is, as shown in  FIG.  4   , a side wall of the inner housing  2  has a uniform thickness over the entire height of the inner housing  2 . The mounting portion  24  is integrally formed on an outer surface of the inner cylinder  21  over the entire height thereof, and the outer housing  1  has a height greater than the maximum height of the inner housing  2 . The upper blocking disc  12  further extends radially outwardly to form a flange portion  16 . A portion of the outer cylinder  11  proximate to the flange portion  16  is formed as a widened portion protruding radially outwardly. The circuit board  300 , shown in  FIG.  2   , formed with a mounting hole or a copper terminal block may be mounted on the widened portion against the flange portion  16  through a welding or crimping process, so that the electrical connector  100  is firmly mounted on the circuit board  300 . Furthermore, the widened portion is formed with a serration portion  13  such that the electrical connector  100  is further firmly mounted on the circuit board. 
     In an exemplary embodiment shown in  FIGS.  3  and  4   , the electrical connector  100  includes two elastic mechanism  4  provided between the upper blocking disc  12  and one end of the inner housing  2  in an axial direction of the electrical connector  100 , and the lower blocking disc  14  and the other end of the inner housing  2 , respectively. The inner housing  2  is movable relative to the outer housing  1  against the elastic force of the elastic mechanisms  4  in the axial direction. After an axial external force exerted on the inner housing  2  is removed, the elastic mechanisms  4  may drive the inner housing  2  to return back to an initial position thereof. Each of the elastic mechanisms  4  is formed as an annular elastic sheet formed into a wave shape in a circumferential direction thereof to increase an elasticity of the elastic mechanisms  4 . 
     As shown in  FIGS.  3  to  7   , in an exemplary embodiment of the disclosure, the inner cylinder  2  is provided with blocking flanges  22  extending radially inwardly on both ends thereof. The blocking flanges  22  have an annular shape and are configured to define the inner through hole  23 . The elastic terminal  3  includes an elastic cylinder formed by crimping a single metal sheet. The blocking flanges  22  of the inner cylinder  21  of the inner housing  2  are constructed to restrict both ends of the elastic cylinder within the inner cylinder  21 , such that the elastic mechanism  4  cannot be separated from the inner cylinder  2 . 
     As shown in  FIGS.  7  to  11   , in an exemplary embodiment of the disclosure, the elastic terminal  3  has a generally cylindrical shape. The elastic terminal  3  includes a generally annular first base  33  and a plurality of elastic sheets  31 ,  32  extending from the first base  33  in the axial direction. Furthermore, a slit  36  is formed between two adjacent elastic sheets  31  and  32 . The plurality of elastic sheets  31 ,  32  include a plurality of sets of elastic sheets. Each set of elastic sheets has a plurality of first electrical contact portions  311  or a plurality of second electrical contact portions  321  protruding inwardly radially. The electrical contact portions of the same set of elastic sheets are substantially arranged on the same circumference, and the electrical contact portions of different sets of elastic sheets are staggered with each other in the axial direction. 
     Referring to  FIGS.  1  and  7  to  11   , since the electrical contact portions  311 ,  321  of different sets of elastic sheets  31 ,  32  of the elastic terminal  3  are staggered with each other in the axial direction, the mating terminal  200  will be sequentially brought into contact with the electrical contact portions  311 ,  321  of the elastic terminal  3  arranged on different circumferences during an insertion of the mating terminal  200  into the electrical connector  100 . Therefore, an force for inserting the mating terminal  200  may be reduced. 
     As shown in  FIGS.  7  to  11   , in an exemplary embodiment of the disclosure, the plurality of sets of elastic sheets include a plurality of first elastic sheets  31  and a plurality of second elastic sheets  32  alternately arranged in the circumferential direction. Further, the first electrical contact portions  311  and the second electrical contact portions  321  are arranged on the whole circumference of the elastic terminal  3 . When the mating terminal  200  is inserted into the elastic terminal  3  in the axial direction, the first electrical contact portions  311  and the second electrical contact portions  321  are sequentially compressed and elastically contracted to be brought in elastic contact with the inserted mating terminal  200 . Therefore, a compressing force applied to the mating terminal  200  may be evenly distributed while reducing the insertion force, thereby maintaining an electrical contact performance between the mating terminal  200  and the elastic terminal  3 . 
     In an exemplary embodiment of the disclosure, a circumference on which the first electrical contact portions  311  of the plurality of first elastic sheets  31  are arranged is symmetrical with a circumference on which the second electrical contact portions  321  of the plurality of second elastic sheets  32  are arranged with respect to a middle cross sectional plane P of the elastic sheets  31 ,  32  in the axial direction, shown in  FIG.  11   . 
     In an exemplary embodiment of the disclosure, shown in  FIG.  11   , each of the elastic sheets  31 ,  32  is formed with a slot  35  extending in the axial direction, and the electrical contact portions  311 ,  321  are located at both sides of the slot  35 . In this way, the force for inserting the mating terminal  200  may be further reduced while increasing contacts of the elastic sheets  31 ,  32  with the mating terminal  200 . Since all of the contacts are electrically connected with each other in parallel, a contact resistance between the mating terminal  200  and the elastic terminal  3  may be reduced. 
     In an exemplary embodiment of the disclosure, the elastic terminal  3  is formed through a crimping process. When the elastic terminal  3  is in a free state, a gap  34 , shown in  FIG.  9   , is formed between both edges  37  of the elastic terminal  3  to be crimped to allow the elastic terminal  3  to expand and contract radially inwardly when mounted in the inner cylinder  21 . In an exemplary embodiment of the disclosure, when the elastic terminal  3  is not mounted in the inner cylinder  21 , the elastic terminal  3  has a maximum outer diameter greater than an inner diameter of the inner cylinder  21 . In this way, when mounted in the inner housing  2 , the elastic terminal  3  is elastically contracted radially such that the both ends  37  of the elastic terminal  3  may be elastically pressed against an inner wall of the inner cylinder  21 . Further, the elastic terminal  3  is reliably held in the inner housing  2  due to the blocking flanges  22  shown in  FIG.  4   . In an alternative embodiment, the opposite ends of the elastic cylinder  31  may be overlapped with each other. 
     In an exemplary embodiment of the disclosure, each of the electrical contact portions  311 ,  321  is formed as a vertex portion when each elastic sheet  31 ,  32  is bent inwardly radially. That is, the elastic sheet  31 ,  32  is bent with each electrical contact portion  311 ,  321  as a vertex. Further, each of the electrical contact portions  311 ,  321  has a generally arc-shaped contact surface protruding inwardly radially to be brought into smooth contact with the mating terminal  200 . In an exemplary embodiment of the disclosure, the circumferences where the contact portions  311 ,  321  of all of the elastic sheets  31 ,  32  are arranged have the substantially same inner diameter, so that the first elastic sheets  31  and the second elastic sheets  32  may apply the same elastic force to the mating terminal  200 . 
     In an exemplary embodiment of the disclosure, as shown in  FIG.  7   , the elastic terminal  3  further includes an annular second base  38  to which an end of each elastic sheet  31 ,  32  opposite to the first base  33  is integrally connected. 
     Referring to  FIGS.  7  and  12   , according to another embodiment of the disclosure, there is provided a method for manufacturing the elastic terminal  3  as described in the above embodiments including: 
     step S 100 : stamping the plurality of elastic sheets  31 ,  32  extending in parallel in a first direction from a single flat metal sheet, as shown in  FIG.  12   , an end of each elastic sheet  31 ,  32  being connected to the first base  33 , and the slit  36  being formed between two adjacent elastic sheets  31  and  32 , so that each of the elastic sheets  31 ,  32  may independently apply an elastic pressure to the mating terminal  200 ; 
     step S 200 : dividing the elastic sheets  31 ,  32  into a plurality of sets of elastic sheets and forming the plurality of first electrical contact portions  311  or the plurality of the second electrical contact portions  321  on each elastic sheet  31 ,  32  of each set of elastic sheets, the electrical contact portions  311 ,  321  of the same set of elastic sheets  31 ,  32  being arranged in a row in a second direction perpendicular to the first direction, and the electrical contact portions  311 ,  321  of different sets of elastic sheets  31 ,  32  being staggered with each other in the first direction; 
     step S 300 : bending each of the elastic sheets  31 ,  32  at each electrical contact portion  311 ,  321  in a third direction perpendicular to the first direction and the second direction; and 
     step S 400 : bending the first base  33  into a generally annular shape, such that the contact portions  311 ,  321  of the same set of elastic sheets  31 ,  32  are arranged on the same circumference, the electrical contact portions  311 ,  321  of different sets of elastic sheets  31 ,  32  are staggered with each other in the first direction, and all of the electrical contact portions  311 ,  321  protrude inwardly radially, thereby forming the elastic terminal  3  having the generally cylindrical shape as shown in  FIG.  7   . 
     As shown in  FIGS.  7  and  12   , in an exemplary embodiment of the disclosure, the plurality of sets of elastic sheets include the plurality of first elastic sheets  31  and the plurality of second elastic sheets  32  arranged alternately in the circumferential direction of the elastic terminal  3 . In the step S 200 , the first electrical contact portions  311  and the second electrical contact portions  321  each having the generally arc-shaped contact surface are formed through the stamping process so as to ensure a smooth contact between the elastic terminal  3  and the mating terminal  200 . 
     As shown in  FIGS.  7 ,  11  and  12   , in an exemplary embodiment of the disclosure, in the step S 200 , each of the first electrical contact portions  311  of the plurality of first elastic sheets  31  is offset from a center line C of the respective elastic sheet  31  in the second direction by the substantially same distance as each of the second electrical contact portions  321  of the plurality of second elastic sheets  32 . In this way, during forming the elastic terminal  3 , the circumference, on which the first electrical contact portions  311  of the plurality of first elastic sheets  31  are arranged, is symmetrical with the circumference, on which the second electrical contact portions  321  of the plurality of second elastic sheets  32  are arranged, with respect to the middle cross sectional plane P of the elastic sheets in the first direction. 
     As shown in  FIGS.  7 ,  11  and  12   , the step S 100  further includes forming a slot  35  extending in the first direction in each of the elastic sheets  31 ,  32 . In the step S 400 , after bending the first base  33  into the generally annular shape, the gap  34  is formed between both edges  37  of the elastic terminal  3  to be crimped. 
     As shown in  FIGS.  7 ,  11  and  12   , in the step S 100 , the end of each elastic sheet  31 ,  32  opposite to the first base  33  is integrally connected to the second base  38 . In this way, it is convenient to perform punching, bending and other operations on each of the elastic sheets  31 ,  32  and all of the elastic sheets  31 ,  32  are evenly stressed. 
     In an exemplary embodiment of the disclosure, the metal sheet is made of copper-nickel material to reduce manufacturing cost of the elastic terminal  3 . In the step S 200 , after forming the electrical contact portions  311 ,  321 , an electroplating layer is electroplated on a surface of the elastic terminal  3  in a flat state, and the electroplating layer has an electrical conductivity greater than that of the metal sheet. For example, the electroplating layer includes beryllium copper material, thus an electrical conductivity of the elastic terminal  3  may be increased so as to reduce the contact resistance between the elastic terminal  3  and the mating terminal  200 . In this way, the electrical connector  100  has good electrical conductivity and mechanical properties. After the electroplating process is completed in the step S 200 , a crimping process is performed in the step S 300 . 
     As shown in  FIGS.  7 ,  11  and  12   , in an exemplary embodiment of the disclosure, a plurality of elastic terminals  3  may be continuously manufactured from a piece of strip-shaped metal sheet. Before the step S 100  is performed, a positioning hole  401  may be formed in a side portion  400  of the strip-shaped metal sheet. Then, the metal sheet is fixed in the positioning hole  401  by a mold before performing the step S 100 . 
     In an exemplary embodiment of the disclosure, a discontinuous connection portion  402  may be formed between the side portion  400  and the first base  33  of the elastic terminal  3  to facilitate cutting the connecting portion  402 . 
     In the method for manufacturing the elastic terminal according to the embodiments of the disclosure, a minimum diameter of the elastic terminal may be changed based on an outer diameter of the mating terminal  200 . For example, as shown in  FIG.  13   , the minimum diameter of the elastic terminal  3 ′ is less than that of the elastic terminal  3  shown in  FIG.  7   . 
     In an exemplary embodiment of the disclosure, as shown in  FIGS.  1  to  6   , in the electrical connector  100 , an inner diameter of the inner through hole  23  is less than that of the outer through hole  15 , and the inner through hole  23  is located in the outer through hole  15  in a state where the inner cylinder  21  occurs a maximum floating relative to the outer housing  1  in a radial direction. In this way, even in the case where the inner cylinder  21  occurs the maximum floating relative to the outer housing  1  in the radial direction, the mating terminal  200  would not be obstructed from being smoothly inserted into the electrical connector  100 . In an exemplary embodiment of the disclosure, the outer through hole  15  and the inner through hole  23  are formed between both ends of each of the outer housing  1  and the inner housing  2  respectively, so as to allow the mating terminal  200  to be inserted into and pass through the electrical connector  100  in the axial direction as shown in  FIG.  2   . 
     In an exemplary embodiment of the disclosure, an elastic reset mechanism is provided between the mounting portion  24  of the inner housing  2  and the outer housing  1 . The inner housing  2  is movable relative to the outer housing  1  against an elastic force of the elastic reset mechanism in the radial direction. After a radial external force exerted on the inner housing  2  is removed, the elastic mechanism  4  may drive the inner housing  2  to return back to the initial position. 
     In an exemplary embodiment of the disclosure, as shown in  FIGS.  14  to  19   , an electrical connector  100 ′ is adapted to be electrically connected to a plug-type mating terminal  200 , and includes an outer housing  1 ′, an inner housing  2 ′, and an elastic terminal  3 . The outer housing  1 ′ includes an outer cylinder  11 ′, and an upper blocking disc  12  and a lower blocking disc  14 ′ radially inwardly extending from both ends of the outer cylinder  11 ′. The upper blocking disc  12  is formed with an outer through hole  15 . The inner housing  2 ′ includes an inner cylinder  21 ′ and a mounting portion  24 ′ surrounding the inner cylinder  21 ′ and integrally formed around the inner cylinder  21 ′. The mounting portion  24 ′ is movably mounted in a space defined by the outer cylinder  11 ′, the upper blocking disc  12 , and the lower blocking disc  14 ′. Further, the inner housing  2 ′ is formed with an inner through hole  23 . The elastic terminal  3  is mounted in the inner cylinder  21 ′ and is configured to be electrically connected with the mating terminal  200  inserted into the inner cylinder  21 ′ through the outer through hole  15  of the outer housing  1 ′. 
     The electrical connector  100 ′ according to an exemplary embodiment of the disclosure further includes an elastic mechanism  4  mounted between the outer housing  1 ′ and the inner housing  2 ′, as shown in  FIG.  15   . The inner housing  2 ′ is movable relative to the outer housing  1 ′ against an elastic force of the elastic mechanism  4 . Since the inner housing  2 ′ is movable relative to the outer housing  1 ′ against the elastic force of the elastic mechanism  4 , the mating terminal  200  mounted in the elastic terminal  3  is allowed to move relative to the outer housing  1 ′ together with the elastic terminal  3  to realize a floating electrical connection between the mating terminal  200  and the electrical connector  100 ′. 
     As shown in  FIGS.  14  to  19   , in an exemplary embodiment of the disclosure, the lower blocking disc  14 ′ is formed by bending inwardly radially after the mounting portion  24 ′ of the inner housing  2 ′ and the elastic mechanism  4  are assembled into the outer housing  1 ′. In this way, a holding force of the lower blocking disc  14 ′ to the inner housing  2 ′ may be increased, and an overall structure of the electrical connector may be simplified. In addition, the upper blocking disc  12  and the outer cylinder  11 ′ may be manufactured at one time through a stamping process, for example. 
     In an exemplary embodiment of the disclosure, the electrical connector  100 ′ may comprise a circular connector and have a generally cylindrical outer profile. Each of the outer housing  1 ′, the elastic terminal  3 , the inner housing  2 ′ and the elastic mechanism  4  is made of a conductive material such as copper, such that the mating terminal  200  is in electrical communication with the outer housing  1 ′. In this way, the outer housing  1 ′ may be directly electrically connected onto a circuit board  300  to realize an electrical connection between the mating terminal  200  and the circuit board  300 . 
     It should be appreciated that the elastic terminal  3  and the elastic mechanism  4  of the electrical connector  100 ′ shown in  FIGS.  14  to  19    may be configured as the elastic terminal  3  and the elastic mechanism  4  of the electrical connector  100  shown in  FIGS.  1  to  11   . 
     In an exemplary embodiment of the disclosure, the mounting portion  24 ′ has a height less than that of the inner cylinder  21 ′, such that at least one portion of the inner cylinder  21 ′ protrudes from at least one of the upper blocking disc  12  and the lower blocking disc  14 ′ of the outer housing  1 ′. In an exemplary embodiment of the disclosure, the mounting portion  24 ′ is formed at a position close to the upper blocking disc  12 , and the at least one portion of the inner cylinder  21 ′ protrudes from the lower blocking disc  14 ′. That is, as shown in  FIG.  15   , the mounting portion  24 ′ protrudes radially outwardly from an end of the inner cylinder  21 ′ close to the lower blocking disc  14 ′ to form an annular flange. In an alternative embodiment, the mounting portion  24 ′ may be composed of a plurality of protrusions located at the same level. 
     In an exemplary embodiment of the disclosure, a portion of the outer cylinder  11 ′ close to an end of the outer cylinder  11 ′ proximate to the lower blocking disc  14 ′ is formed as a stepped portion  17 , as shown in  FIGS.  18  to  21   , which is configured to mount the outer housing  1 ′ into a mounting hole of the circuit board  300 . The circuit board  300  formed with the mounting hole or a copper terminal block may be mounted on the stepped portion  17  through a welding or crimping process and abutted against a radially extending portion of the stepped portion  17 , so that the electrical connector  100 ′ is firmly mounted on the circuit board  300  as shown in  FIG.  16   . Further, a serration portion is formed on an axially extending portion of the stepped portion  17  such that the electrical connector  100 ′ is further firmly mounted on the circuit board  300 . In this way, the inner cylinder  21 ″ of the electrical connector  100 ″ passes through the circuit board  300 , which may reduce an overall height of an electronic device including the circuit board  300  and the electrical connector  100 . 
     In an exemplary embodiment of the disclosure, an inner diameter of the inner through hole  23  is less than that of the outer through hole  15 , and the inner through hole  23  is located in the outer through hole  15  in a state where the inner cylinder  21 ′ occurs a maximum floating relative to the outer housing  1 ′ in a radial direction. In this way, even in the case where the inner cylinder  21 ′ occurs the maximum floating relative to the outer housing  1 ′ in the radial direction, the mating terminal  200  would not be obstructed from being smoothly inserted into the electrical connector  100 ′. In an exemplary embodiment of the disclosure, the outer through hole  15  and the inner through hole  23  are formed between both ends of each of the outer housing  1 ′ and the inner housing  2 ′, respectively, so as to allow the mating terminal  200  to be inserted into and pass through the electrical connector  100 ′ in an axial direction as shown in  FIG.  10   . 
     In an exemplary embodiment of the disclosure, as shown in  FIGS.  20  to  22   , an electrical connector  100 ″ is adapted to be electrically connected to a plug-type mating terminal  200 , and includes an outer housing  1 ″, an inner housing  2 ″ and an elastic terminal  3 . The outer housing  1 ″ includes an outer cylinder  11 ″, and an upper blocking disc  12  and a lower blocking disc  14 ″ radially inwardly extending from both ends of the outer cylinder  11 ″. The upper blocking disc  12  is formed with an outer through hole  15 . The inner housing  2 ″ includes an inner cylinder  21 ″ and a mounting portion  24 ′ surrounding the inner cylinder  21 ″ and integrally formed around the inner cylinder  21 ″. The mounting portion  24 ′ is movably mounted in a space defined by the outer cylinder  11 ″, the upper blocking disc  12  and the lower blocking disc  14 ″. Further, the inner housing  2 ″ is formed with an inner through hole  23 . The elastic terminal  3  is mounted in the inner cylinder  21 ″ and is configured to be electrically connected with the mating terminal  200  inserted into the inner cylinder  21 ″ through the outer through hole  15  of the outer housing  1 ″. 
     The electrical connector  100 ″ according to an exemplary embodiment of the disclosure further includes an elastic mechanism  4  mounted between the outer housing  1 ″ and the inner housing  2 ″. The inner housing  2 ″ is movable relative to the outer housing  1 ″ against an elastic force of the elastic mechanism  4 . Since the inner housing  2 ″ is movable relative to the outer housing  1 ″ against the elastic force of the elastic mechanism  4 , the mating terminal  200  mounted in the elastic terminal  3  is allowed to move relative to the outer housing  1 ″ together with the elastic terminal  3  to realize a floating electrical connection between the mating terminal  200  and the electrical connector  100 ″. 
     In an exemplary embodiment of the disclosure, the lower blocking disc  14 ″ shown in  FIGS.  21  and  22    is assembled into a lower end of the outer cylinder  11 ″ after the inner housing  21 ″ and the elastic mechanism  4  are assembled into the lower end of the outer housing  1 ″. For example, the lower blocking disc  14 ″ may be assembled into the outer cylinder  11 ″ by a thread connection, a snap connection, a welding connection or any combination thereof. 
     In an exemplary embodiment of the disclosure, a portion of the outer cylinder  11 ″ close to the lower end thereof proximate to the lower blocking disc  14 ″ is formed as a stepped portion  17  configured to mount the outer housing  1 ″ into a mounting hole of the circuit board  300 . The circuit board  300  formed with the mounting hole or a copper terminal block may be mounted on the stepped portion  17  through a welding or crimping process and abutted against a radially extending portion of the stepped portion  17 , so that the electrical connector  100 ″ is firmly mounted on the circuit board. Further, a serration portion is formed on an axially extending portion of the stepped portion  17  such that the electrical connector  100 ″ is further firmly mounted on the circuit board  300 . 
     It should be understood that the electrical connector  100 ″ shown in  FIGS.  14  to  16    is different from that shown in  FIGS.  8  to  13    only in the lower blocking disc  14 ′,  14 ″, and the elastic terminal and the elastic mechanism of the electrical connector  100 ″ shown in  FIGS.  20    to  22  may be configured as the elastic terminal  3  and the elastic mechanism  4  of the electrical connector  100  shown in  FIGS.  1  to  11   . 
     An electrical connector according to another embodiment shown in  FIG.  23    is a modification of the electrical connector shown in  FIGS.  14  to  16   . As shown in  FIG.  23   , the inner housing includes an inner cylinder  21 ″ and a mounting portion  24 ″ surrounding the inner cylinder  21 ″ and integrally formed around the inner cylinder  21 ′. The mounting portion  24 ″ is movably mounted in a space defined by an outer cylinder  11 ″, and an upper blocking disc  12  and a lower blocking disc  14 ″ of the outer housing  1 ″. Further, the inner housing is formed with an inner through hole. The elastic terminal  3  is mounted in the inner cylinder  21 ″ and is configured to be electrically connected with the mating terminal  200  inserted into the inner cylinder  21 ″ through the outer through hole of the outer housing  1 ″. The mounting portion  24 ″ is formed between the upper blocking disc  12  and the lower blocking disc  14 ″, and an upper portion and a lower portion of the inner cylinder  21 ″ protrude from the upper blocking disc  12  and the lower blocking disc  14 ″, respectively. 
     In an exemplary embodiment of the disclosure, a portion of the outer cylinder  11 ″ close to an end of the outer cylinder  11 ″ proximate to the lower blocking disc  14 ″ is formed as a stepped portion  17  which is configured to mount the outer housing  1 ″ into a mounting hole of the circuit board  300 . The circuit board  300  formed with the mounting hole or a copper terminal block may be mounted on the stepped portion  17  through a welding or crimping process and abutted against a radially extending portion of the stepped portion  17 , so that the electrical connector as shown in  FIG.  17    is firmly mounted on the circuit board  300 . Further, a serration portion is formed on an axially extending portion of the stepped portion  17  such that the electrical connector is further firmly mounted on the circuit board. In this way, the inner cylinder  21 ″ of the electrical connector passes through the circuit board  300 , which may reduce an overall height of an electronic device including the circuit board  300  and the electrical connector. 
     According to another embodiment of the disclosure, as shown in  FIGS.  2  and  16   , there is provided an electronic device including the electrical connectors  100 ,  100 ′,  100 ″ described in any of the above embodiments and a circuit board  300  to which the electrical connector  100 ,  100 ′,  100 ″ is electrically connected. Further, the outer cylinder of the electrical connector  100 ,  100 ′,  100 ″ passes through a mounting hole of the circuit board  300  and is electrically connected with the circuit board  300 . In an alternative embodiment, an end surface of the upper blocking disc  12  or the lower blocking disc  14  of the electrical connector  100 ,  100 ′,  100 ″ may be welded to the circuit board  300 . 
     It should be appreciated by those skilled in this art that the above embodiments are intended to be illustrative, and many modifications may be made to the above embodiments by those skilled in this art. Further, various structures described in various embodiments may be freely combined with each other without conflicting in configuration or principle. 
     Although the disclosure has been described hereinbefore in detail with reference to the attached drawings, it should be appreciated that the disclosed embodiments in the attached drawings are intended to illustrate the embodiments of the disclosure by way of example, and should not be construed as a limitation to the disclosure. 
     Although a few embodiments of the general inventive concept of the disclosure have been shown and described, it would be appreciated by those skilled in the art that changes or modification may be made to these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in claims and their equivalents. 
     It should be noted that, the word “include” doesn&#39;t exclude other elements or steps, and the word “a” or “an” doesn&#39;t exclude more than one. In addition, any reference numerals in the claims should not be interpreted as the limitation to the scope of the disclosure.