Abstract:
A shielding connector has a female and male housings ( 30; 60 ), each of which has an inner housing ( 31, 61 ) that accommodates terminal fittings ( 20; 25 ). Metal shells ( 50, 80 ) are mounted on the peripheries of the inner housings ( 31, 61 ) and electromagnetically shield the female and male terminal fittings ( 20; 25 ) when the housings ( 30; 60 ) are connected. The metal shells ( 50; 80 ) are configured to achieve secure mounting, effective shielding and a small cross section. A detector ( 90 ) is provided to ensure complete connection and is configured to prevent inadvertent separation of the housings ( 30; 60 ).

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a shielding connector and to a connector with a connection fit-on detecting function. 
   2. Description of the Related Art 
   Japanese Patent Application Laid-Open No. 11-219758 discloses a shielding connector that has a female housing and a male housing to be fitted thereon. The female and male housings each have an outer housing and an inner housing that is suspended in the outer housing through a plurality of ribs. The inner housings accommodate terminal fittings connected to the ends of shielding electric wires. A metal shell is fit on the periphery of the rear end of the inner housing and has slits for receiving the ribs. The metal shell is configured to contact the braided wire of the shielding electric wire. The corresponding female and male terminal fittings are connected to each other when the female and male housings have been fit together. At the same time, the projected ends of the female and male metal shells fit on each other and cover the area of the connection between the female and male terminal fittings. Thus, the female and male terminal fittings are shielded electromagnetically. 
   The inner housing of the above-described shielding connector is suspended in the outer housing by the ribs. Thus, it is necessary to form the slits on the metal shell. However, the slits align when the projected ends of the female and male metal shells are fit together and the metal shells are open at the positions where the slits align. As, a result, the shielding function of the connector deteriorates. 
   Each metal shell of the above-described connector is formed from a metal plate that is bent into a rectangular or oblong tube. A convexity at one end of the plate is forcibly fit to a concavity at the other end thereof to form the metal shell. A wide metal shell is liable to open at its widthwise center, and the metal shells will not fit smoothly together if the projected end of either shell opens. Additionally, a gap is formed between the metal shells if either shell opens, and the contact pressure of the contact plate interposed therebetween deteriorates. Thus the electrical connection is unstable and the connector has a poor shielding function. 
   The male shielding connector of JP 11-219758 is shown in  FIG. 37  herein. With reference to  FIG. 37 , the male shielding connector m has an outer housing  1   m  and an inner housing  3   m . A cavity  2   m  is formed in the inner housing  3   m  to accommodate a terminal fitting connected to the end of a shielding electric wire. A metal shell  4   m  is inserted into the outer housing  1   m  from its rear end (left side in  FIG. 37 ) and is mounted on the periphery of the inner housing  3   m . The metal shell  4   m  is configured for contacting the braided wire of the shielding electric wire. 
   A locking claw  5   m  is formed on the outer surface of the metal shell  4   m  to prevent the metal shell  4   m  from slipping off the periphery of the inner housing  3   m . A lock  6   m  is formed on the inner peripheral surface of the outer housing  1   m  opposed to the outer surface of the metal shell  4   m  and a rib  7   m  extends to both sides of the lock  6   m . The locking claw  5   m  passes the rib  7   m  and rides across the lock  6   m  as the metal shell  4   m  is inserted into the outer housing  1   m  and onto the periphery of the inner housing  3   m . Thus, the locking claw  5   m  is locked to the front surface of the lock  6   m , and the metal shell  4   m  is mounted on the periphery of the inner housing  3   m  without slipping off. The rib  7   m  at both sides of the lock  6   m  minimizes the elastic deformation of the locking claw  5   m  and enhances locking. 
   The locking construction of the shielding connector of  FIG. 37  requires the stepped configuration of locking claw  6   m  and the rib  7   m  on the inner peripheral surface of the outer housing  1   m . Thus the peripheral wall of the outer housing  1   m  is thick and hence the connector housing is radially large. 
   The female shielding connector of Japanese Patent Application Laid-Open No. 11-219758 is shown in  FIGS. 38 and 39  herein. With reference to  FIGS. 38 and 39  the female shielding connector f has an outer housing  1   f  and an inner housing  3   f . The inner housing  3   f  is formed with a cavity  2   f  to accommodate a terminal fitting connected to the end of the shielding electric wire. A metal shell  4   f  is inserted into the outer housing  1   f  from its rear side (right side in  FIG. 38 ) and is mounted on the periphery of the inner housing  3   f . The metal shell  4   f  is configured to contact the braided wire of the shielding electric wire. 
   A lock  5   f  is formed as a step on the wall  2   f A of the upper side of the cavity  2   f , and the locking claw  6   f  is bent from the corresponding surface of the metal shell  4   f . The metal shell  4   f  is inserted into the outer housing  1   f  from its rear side and is mounted on the periphery of the inner housing  3   f . As a result, the locking claw  6   f  is pressed by the lock  5   f  and elastically deforms. The locking claw  6   f  returns to its original state due to its resiliency and is locked to the lock  5   f  when the metal shell  4   f  is inserted to the predetermined position. Thus, the metal shell  4   f  is mounted on the periphery of the inner housing  3   f  without slipping off. 
   The lock  5   f  is formed as a step on the upper wall  2   f A of the cavity  2   f . Thus, the diameter of the inner housing  3   f  is large, and the entire connector housing is large in the radial direction. 
   Japanese Patent Application Laid-Open No. 2002-141145 and  FIG. 40  herein show another connector. With reference to  FIG. 40 , the connector includes a male housing  1   a  and a female housing  2   a  that can be fit on the male housing  1   a . The female housing  2   a  defines a flexing space  3   a  and a locking arm  4   a  that deforms elastically into the flexing space  3   a  while the male housing  1   a  and the female housing  2   a  are being fitted together. The locking arm  4   a  returns elastically to its original state and is locked to the male housing  1   a  when the male and female housings  1   a  and  2   a  have been fit together normally for holding the male and female housings  1   a  and  2   a  together. 
   The female housing  2   a  also has a detector  5   a  that can move between a wait position (shown with two-dot chain line in  FIG. 40 ) disposed away from the flexing space  3   a  and a detection position (shown with solid line in  FIG. 40 ) disposed inside the flexing space  3   a . The detector  5   a  can be pressed from the detection position toward the flexing space  3   a  when the male and female housings  1   a  and  2   a  are in a semi-fit-on state. However, the detector  5   a  strikes the locking arm  4   a  that has entered the flexing space  3   a  to prevent or limit the pressing of the detector  5   a . The locking arm  4   a  moves away from the flexing space  3   a  when the male and female housings  1   a  and  2   a  are in a normal fit-on state. As a result, the detector  5   a  can advance to the detection position to detect the fit-on state of the male and female housings  1   a  and  2   a.    
   The male and female housings  1   a  and  2   a  may have to be separated from each other for maintenance. For this purpose, a catch  5 A at the rear end of the detector  5   a  can be gripped manually and pulled rearward. As a result, the detector  5   a  returns to the wait position, while the semi-locking of the housings  1   a  and  2   a  is being released. The locking arm  4   a  then can be deformed elastically to perform an unlocking operation, and the male and female housings  1   a  and  2   a  can be separated. 
   The connector of  FIG. 40  has an advantage of permitting the detector  5   a  to be returned easily to the wait position so that the housings  1   a  and  2   a  can be unlocked and separated. However, foreign matter may press the catch  5 A accidentally and return the detector  5   a  to the wait position. Thus, the housings  1   a  and  2   a  can be separated unintentionally. 
   The invention has been made in view of the above-described problems. Accordingly, it is an object of the present invention to allow a metal shell to enhance a shielding function. 
   It is another object of the invention to improve the locking construction of the metal shell and to thereby make the housing more compact. 
   A further object of the invention to achieve a smooth fit of the female and male metal shells on each other and to enhance the shielding function of a shielding connector. 
   It is a further object of the invention to prevent an inadvertent return of a detection member to a wait position. 
   SUMMARY OF THE INVENTION 
   The invention is a shielding connector with a female housing and a male housing to be fitted on the female housing. The female and male housings each include inner and outer housings. The inner housing is suspended through a connection and accommodates terminal fittings connected to ends of shielding electric wires. 
   A metal shell is inserted into a rear end of the outer housing and is configured to contact a braided wire of the shielding electric wire. The metal shell has slits for receiving the connections on a periphery of the inner housing. Projecting ends of the metal shells fit together and cover an area of connection between the terminal fittings. The slits of the metal shell of the female housing and the slits of the metal shell of the male housing are offset from each other in a widthwise direction. Therefore the projected end of the female metal shell closes the slits of the male metal shell, and the projected end of the male metal shell closes the slits of the female metal shell when the female and male metal shells are fit together. The entire region of the projected end of the female metal shell is covered with the male metal shell, and the entire region of the projected end of the male metal shell is covered with the female metal shell. Thus, shielding performance is enhanced. 
   Guides preferably are provided to guide the connections smoothly into the slits. Thus, the metal shell is mounted easily on the inner housing. 
   Each metal shell may be split and a joining portion may be formed on surfaces of the two split shells. The two split shells of the metal shell are connected to each other by caulking opposed side surfaces together. Therefore the metal shells will not open and keep a specified configuration. 
   A locking claw preferably projects from an inner surface of the metal shell, and a shell lock preferably is formed concavely inside the housing. The shell lock unremovably engages the locking claw. The conventional locking claw projects out, whereas the locking claw of the subject invention preferably projects in. Therefore, the housing of the subject invention does not require a thick outer wall to form the shell lock, and the housing is radially compact. 
   The housing preferably has a plurality of cavities for accommodating terminal fittings. The shell lock of the housing preferably is formed between two cavities. Thus, the shell lock utilizes dead space, and it is unnecessary to thicken the peripheral wall of the housing. Accordingly, the housing is radially compact. 
   The housing preferably comprises two shell locks formed on opposite peripheral surfaces of the housing. Thus, a strong and balanced force is maintained for preventing slip-off of the metal shell, while still keeping a compact housing. 
   A lance preferably is formed in the cavity of the terminal fitting accommodation part and unremovably locks the terminal fitting. The lock preferably is formed by cutting out a part of a wall that prevents an excessive elastic deformation of the lance. Therefore the connector prevents excessive elastic deformation of the lance while making the housing compact radially. 
   The male housing preferably has an opening prevention rib that contacts an outer surface of the projected end of the male metal shell and prevents the male metal shell from opening. Thus both metal shells can be fit together smoothly. Further there is no clearance between the metal shells after they are fit together. 
   A deformable contact plate preferably is raised from a portion near the projected end of the female metal shell and contacts an inner surface of the male metal shell. The contact plate maintains a desired contact pressure between the metal shells and stabilizes the electrical connection between the metal shells. Thus, a shielding function of the shielding connector is enhanced. 
   The projected end of the female metal shell forward of the contact plate is folded in and contacts a peripheral surface of the terminal fitting accommodation part on which the female metal shell is mounted. The folded portion forms a flexing space that permits the contact plate to deform elastically. Thus, the contact plate deforms elastically into the flexing space when the shells have been fit together and contacts the inner peripheral surface of the male metal shell. Accordingly, the contact plate secures an appropriate flexing amount and a high contact pressure by reducing the resistance in fitting the metal shells together. Further, the strength of the front end of the metal shell is increased. 
   A first of the housings preferably includes a resiliently deformable lock arm that deforms into a deformation space while the housings are being fit together. However, the lock arm returns resiliently to its original state and engages a second of the housings when both housings have been fit together. 
   The connector may have detector that is movable between a wait position spaced from the deformation space and a detection position disposed in the deformation space. The detector strikes the lock arm that is in the deformation space while the housings are being fit together. Thus, the detector cannot move from the wait position to the detection position. However, the detector can advance to the detection position when the housings have been fit together normally. 
   The detector preferably has a catch that can be used to return the detector toward the wait position. The catch is hidden at a rear side of the locking arm. However, part of the catch can be caught by a jig when the detector is at the detection position so that the detector can be returned intentionally to the wait position. Thus, foreign matter cannot press the catch. 
   An elastically deformable locking piece may be formed on the detector and is locked to a locking portion on the first housing. Thus, the detector is prevented from moving from the wait position to the detection position before the housings are fit together. The second housing has a release portion that engages and deforms the locking piece when the housings are fit together to unlock the locking piece from the lock. Thus it is possible to prevent the detector from being returned accidentally and to prevent the female and male housings from being separated unintentionally. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded sectional view of the male and female connectors. 
       FIG. 2  is a cross sectional view of the male and female connectors in their fully connected condition. 
       FIG. 3  is a front view of a female housing according to the invention. 
       FIG. 4  is an exploded vertical sectional view of a female metal shell and the female housing. 
       FIG. 5  is an exploded horizontal sectional view of the female metal shell and the female housing. 
       FIG. 6  is a plan view of the metal blank for forming one part of the split female metal shell. 
       FIG. 7  is a perspective view of the completed part of female metal shell formed from the blank in FIG.  4 . 
       FIG. 8  is an exploded vertical sectional view of the two halves of the female metal shell. 
       FIG. 9  is a vertical sectional view of the completed female metal shell. 
       FIG. 10  is a section taken along line  10 — 10  in FIG.  8 . 
       FIG. 11  is a section taken along line  11 — 11  in FIG.  9 . 
       FIG. 12  is a front view showing the female housing in which the female metal shell has been mounted. 
       FIG. 13  is an exploded sectional view of the female connector. 
       FIG. 14  is a front view showing a male housing. 
       FIG. 15  is a horizontal sectional view of the male metal shell. 
       FIG. 16  is an exploded sectional view of a male metal shell and the male housing. 
       FIG. 17  is a cross sectional view taken along line  17 — 17  in FIG.  16 . 
       FIG. 18  is an exploded cross-sectional view of the female and male housings with the shells mounted therein. 
       FIG. 19  is a sectional view of the connected female and male housings and shells. 
       FIG. 20  is a front view showing the male housing in which the male metal shell has been mounted. 
       FIG. 21  is an exploded sectional view of the male connector. 
       FIG. 22  is a partial sectional view showing a state before the male and female metal shells are connected to each other. 
       FIG. 23  is a partial sectional view showing a state in which the male and female metal shells have been connected to each other. 
       FIG. 24  is an exploded plan view of female and male connectors. 
       FIG. 25  is a plan view showing the female housing in which a detector is mounted on a wait position. 
       FIG. 26  is a rear view showing the female housing. 
       FIG. 27  is a vertical sectional view of the female housing. 
       FIG. 28  is a perspective view showing the detector. 
       FIG. 29  is a partial vertical sectional view showing a state in which female and male housings are being fitted on each other. 
       FIG. 30  is a partial vertical sectional view showing an operation of a locking piece of the detector. 
       FIG. 31  is a partial vertical sectional view showing a state in which the female and male housings have been fit together. 
       FIG. 32  is a partial vertical sectional view showing the state shown in FIG.  31 . 
       FIG. 33  is a partial vertical sectional view showing the operation of the locking piece of the detector. 
       FIG. 34  is a side view of an alternate female metal shell. 
       FIG. 35  is an exploded sectional view showing a female metal shell on a female housing according to another embodiment of the invention. 
       FIG. 36  is a front view showing the female housing of  FIG. 35  in which the female metal shell has been mounted. 
       FIG. 37  is a vertical sectional view showing an example of a conventional male housing and male metal shell. 
       FIG. 38  is a vertical sectional view showing an example of a conventional female housing and female metal shell. 
       FIG. 39  is a front view showing the conventional housing and shell of FIG.  38 . 
       FIG. 40  is a vertical sectional view showing the known male and female housings connected. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A shielding connector according to a first embodiment of the invention is described below with reference to  FIGS. 1 through 33 . The shielding connector of this embodiment has a female connector F and a male connector M that can be fitted on the female connector F, as shown in  FIGS. 1 and 2 . A mating side of each of the female connector F and the male connector M is defined as the front side herein. 
   As shown in  FIGS. 1-3 , the female connector F has a female housing  30 . Three female terminals  20  are fixed to ends of shielding electric wires  10  and are accommodated in the female housing  30 , as shown in  FIG. 11. A  female metal shell  50  also is accommodated in the female housing  30 . 
   The shielding electric wire  10  has a known construction. More specifically, a core wire  11 , an insulating inner coating  12 , a braided wire  13 , and an insulating outer coating  14  are concentrically disposed on the shielding electric wire  10  and are exposed sequentially at the end thereof. The end of the braided wire  13  is folded rearward and is placed on the end of the insulating outer coating  14 . The braided wire  13  then is caulked to the end of the insulating outer coating  14  with a metal pipe  15 . 
   The female terminal  20  is formed by press working a metal plate. The female terminal  20  has a quadrangular connection portion  22  accommodating a contact piece  21  that contacts a tab  26  of a mating male terminal fitting  25 . The female terminal  20  is crimped to the end of the shielding electric wire  10  by caulking a barrel  23  at the rear end of the female terminal  20  to the core wire  11  and the insulating inner coating  12 . 
   The female housing  30  is molded unitarily from a synthetic resin and includes an inner housing  31  and an outer housing  32 , as shown in  FIGS. 4 and 5 . The inner housing  31  is oblong in section and three cavities  33  extend longitudinally through the inner housing  31 . The cavities  33  are arranged widthwise across the inner housing  31 . The female terminals  20  fixed to the ends of the shielding electric wires  10  are inserted into the cavities  33  from the rear and are locked to respective lances  33 A on the bottom surface of the cavities  33 . Additionally, the exposed portion at the end of the insulating inner coating  12  of the shielding electric wire  10  is prevented from slipping off the female terminals  20 . 
   The outer housing  32  is a little larger than the inner housing  31  and is disposed rearward from the rear end of the inner housing  31 . Thus, the outer housing  32  covers the periphery of the rear portion of the inner housing  31 . As shown in  FIG. 3 , an oblong ring-shaped insertion space  34  is formed between the peripheral surface of the inner housing  31  and the inner peripheral surface of the outer housing  32  for receiving the female metal shell  50 . Upper and lower ribs  35  extend in the axial direction of the female housing  30  and connect an overlapped portion of the peripheral surface of the inner housing  31  at its rear end and the inner peripheral surface of the outer housing  32  at its front end, as shown in  FIGS. 4 and 5 . Accordingly the inner housing  31  is suspended in the outer housing  32  by the ribs  35 . 
   As shown in  FIG. 3 , the ribs  35  are at positions corresponding to the widthwise center of each of the right and left cavities  33  of the female housing  30 . 
   A hood  36  is formed on the periphery of the outer housing  32  and extends to the front end of the inner housing  31 , as shown in  FIG. 4. A  high dome  37  is formed at the center of an upper surface of the hood  36  of the female housing  30  and extends rearward by a predetermined length from the front end of the hood  36 . A ceiling surface of a portion of the dome  37  projected from the rear end of the hood  36  is open. 
   A mounting portion  39  for a bracket (not shown) is formed on a lower surface of the hood  36 . 
   A long narrow locking arm  40  is formed in the rear of the dome  37 . A groove  41  is formed on a lower surface of the locking arm  40  and has a closed front end. A central portion of each of right and left side walls of the groove  41  is connected to an upper surface of the inner housing  31  through a support  42  so that the locking arm  40  can swing on the support  42  like a seesaw. 
   A locking hole  43  is formed at the front end of the groove  41  of the locking arm  40  and has an open upper surface. A pressing portion  44  is formed at the rear end of the locking arm  40  to deform the locking arm  40  pivotally. The pressing portion  44  faces the opening in the ceiling of the dome  37 . More specifically, the pressing portion  44  is wider than the locking arm  40  and generally defines a pentagon in a plan view. The pressing portion  44  is slightly higher than the upper surface of the locking arm  40 . A stepped slip prevention portion  45  is formed at the front of an upper surface of the pressing portion  44 . A flange  46  is projected along the pointed rear end of the pressing portion  44 . A jig insertion opening  44 A is formed centrally at the rear edge of the pressing portion  44  of the locking arm  40  for receiving a jig J. 
   A receiving plate  47  (see  FIG. 26 ) projects from right and left surfaces of the rear end of the locking arm  40 . 
   The female metal shell  50  is shown in  FIGS. 6-11  and is composed of two split shells  51 , each of which is formed by bending the metal blank shown in FIG.  6 . Each split shell  51  is a shallow channel, as shown most clearly in FIG.  7 . 
   Front and rear insertion pieces  52  project from one of the side plates, whereas front and rear receiving portions  53  are formed at the other of the side plates. The two split shells  51  are opposed to each other symmetrically with respect to a point. Then, as shown in  FIGS. 8-11 , the insertion piece  52  is inserted into the corresponding receiving portion  53  and caulked to form the quadrangular female metal shell  50 . 
   Three contact pieces  54  are folded in at the rear edge of each of upper and lower surfaces of the female metal shell  50 , and are configured to contact the metal pipe  15  fit on the end of the braided wire  13  of each shielding electric wire  10 . Thus, the metal pipe  15  is sandwiched between the upper and lower contact pieces  54  arranged in the right-to-left direction. A contact plate  55  is raised rearward from the front end of each of the upper, lower, right and left surfaces of the female metal shell  50  for contacting a mating metal shell  80 . A contact projection  55 A is projected from the outer surface of each contact plate  55 . 
   As shown in  FIGS. 6 and 7 , two slits  56  are formed on each of the upper and lower surfaces of the female metal shell  50  for receiving the ribs  35 . As explained above, the ribs  35  suspend the inner housing  31  inside the outer housing  32  of the female housing  30 . Each slit  56  is formed by cutting the female metal shell  50  from the front end of each of the upper and lower surfaces thereof to approximately the center thereof in a front-to-back direction. The width of each slit  56  is so set that the rib  35  is inserted tightly therein. A guide  56 A is formed at the entrance of the slit  56  and is wider than the remainder of the slit  56 . The guide  56 A has a rounded step  56 B rearward from the entrance of the slit  56 . 
   The front end of each surface of the female metal shell  50  is folded in by a predetermined length, with the front end in close contact with the lower surface of the female metal shell  50  to form a folded portion  57 . 
   The female metal shell  50  can be fitted on the periphery of the inner housing  31 . The female metal shell  50  extends from approximately the center of the inner housing  31  in its longitudinal direction to a position a little rearward from the center of the outer housing  32  in its longitudinal direction, as shown in FIG.  13 . When the female metal shell  50  is fit on the periphery of the inner housing  31 , the folded portion  57  contacts the peripheral surface of the inner housing  31  to from a flexing space  57 A that permits the contact plate  55  to deform elastically inward. 
   Locking claws  58  are raised rearward at positions inward from the slits  56  on the upper and lower surfaces of the female metal shell  50 . A locking groove  48  is formed on the upper and lower surfaces of the inner housing  31  at a position corresponding to the locking claws  58  for locked engagement with the locking claws  58 . 
   The male connector M has a male housing  60 , as-shown in  FIGS. 1 ,  2 ,  14  and  16 - 21 . Three male terminals  25  are fixed to ends of the shielding electric wires  10  and are accommodated in the male housing  60 . A male metal shell  80  also is accommodated in the male housing  60 . 
   Each male terminal  25  is formed by press working a metal plate. More particularly, each male terminal  25  has a front end formed into a tab  26  and a rear end formed into a barrel  27 . The barrel  27  is crimped or caulked to the core wire  11  and the insulating inner coating  12  at the end of the shielding electric wire  10 . 
   The male housing  60  is molded unitarily from a synthetic resin and has an inner housing  61  and an outer housing  62 . The inner housing  61  is oblong in section. Three cavities  63  are arranged widthwise in the inner housing  61 , and a fit-in concavity  65  is formed in the front end of the inner housing  61  of the male housing  60  for receiving the front end of the inner housing  31  of the female housing  30 . The male terminals  25  fixed to the ends of the shielding electric wires  10  are inserted into the cavities  63  from the rear and are locked to lances  66  formed on the bottom surface of the cavities  63  respectively. Thus, the male terminals  25  are prevented from slipping out of the cavities  63 , and the tabs  26  of the male terminals  25  project into the fit-in concavity  65 . 
   The outer housing  62  is a little larger and longer than the inner housing  61  and is disposed forward from the rear end of the inner housing  61 . Thus, the outer housing  62  covers the periphery of front and rear portions of the inner housing  61 . A small hood  66  of the outer housing  62  can be fit in the hood  37  of the female housing  30 . 
   An oblong ring-shaped insertion space  68  is formed between the peripheral surface of the inner housing  61  and the inner peripheral surface of the outer housing  62 , as shown in  FIG. 14 , for receiving the male metal shell  80 . Upper and lower axially extending ribs  69  extend through the space  68  to connect the longitudinal center of peripheral surface of the inner housing  61  and the inner peripheral surface of the outer housing  62  at a rear position of the small hood  66  thereof. Accordingly the inner housing  61  is suspended in the outer housing  62  by the ribs  69 . 
   The ribs  69  are over and under the right and left cavities  33 , and the lower ribs  69  are a little closer to the central cavity  63 , as shown in FIG.  14 . 
   A locking projection  70  is disposed at a front end of an upper portion of the peripheral surface of the outer housing  62 . Right and left guide walls  71  are formed on the upper surface of the outer housing  62  to guide the locking arm  38  therebetween. The locking projection  70  is formed between the right and left guide walls  71  and close to the line connecting the front ends of the right and left guide walls  71 . The locking projection  70  can fit in the locking hole  43  of the locking arm  40 . More particularly, the front side of the locking arm  40  rides across the locking projection  70  as the female and male housings  30  and  60  are fit together. Additionally, the rear of the locking arm  40  pivotally deforms and projects into a flexing space  48 , as shown in FIG.  29 . The locking arm  40  returns elastically to its original state when the female and male housings  30  and  20  have been fit together normally. Thus the locking projection  70  can fit in the locking hole  43  (see FIG.  31 ). 
   A mounting portion  72  for a bracket (not shown) is formed on a lower peripheral surface of the outer housing  62 . 
   As shown in  FIG. 16 , a hole  75  reaching the vicinity of the base of the lance  63 A is formed on a bottom wall  74  of a flexing space  73  of the lance  63 A in the right and left cavities  63 , with the position of the hole  75  located a little toward the central cavity  63 . The inner portion of the hole  75  is opened on the lower surface of the inner housing  61  to form a locking hole  76 . 
   An escape groove  77  is formed on the lower surface of the inner housing  61  at a position rearward from the locking hole  76  to reduce the elastic deformation of the locking claw  85 . 
   Six opening prevention ribs  79  are formed on the inner surface of the small hood  66 . As shown in  FIG. 20 , the opening prevention ribs  79  are formed longitudinally in the region where the male metal shell  80  is projected into the small hood  66 . As shown in  FIG. 20 , two opening prevention ribs  79  are formed on each of upper and lower inner peripheral surfaces of the small hood  66 . One of the two opening prevention ribs  79  is disposed between the left and intermediate cavities  63  and the other is disposed between the right and intermediate cavities  63 . One opening prevention rib  79  is formed at a position intermediate in the height of the male housing  60  on each of the right and left inner peripheral surfaces of the small hood  66 . 
   The male metal shell  80  is quadrangular, as shown in  FIGS. 15-18 , and is configured to fit on the periphery of the female metal shell  50 , as shown in FIG.  19 . Additionally, the male metal shell  80  has a length to project forward and rearward from the inner housing  61 , as shown in FIG.  21 . Thus, a portion of the male metal shell  80  projected from the front end of the inner housing  61  can be fit on the front end of the female metal shell  50 , as shown in FIG.  19 . 
   The male metal shell  80  is constructed of two split shells  81  of the same configuration and connected to each other. The construction for connecting the split shells  81  to each other is similar to construction for connecting the split shells  51  of the female metal shell  50 . 
   Three contact pieces  84  are folded in at the rear edge of each of upper and lower surfaces of the male metal shell  80  and contact the metal pipe  15  fit on the periphery of the braided wire  13  of each shielding electric wire  10 . Thus, the metal pipe  15  is sandwiched between the upper and lower contact pieces  84  arranged in the right-to-left direction. 
   As shown in  FIG. 15 , two slits  86  are formed on each of upper and lower surfaces of the male metal shell  80  for receiving the ribs  69 . Each slit  86  is formed by cutting the male metal shell  80  from the front end of each of the upper and lower surfaces thereof to approximately the center in the front-to-back direction. The width of the slit  86  is set so that the rib  69  is inserted tightly therein. 
   With reference to  FIG. 18 , the slits  86  of the male metal shell  80  are disposed widthwise inward to prevent them from aligning with the slits  56  of the female metal shell  50 . 
   A guide  87  that is wider than the slit  86  is formed at the entrance of the slit  86 . The guide  87  has a rounded step  87 A disposed rearward from the entrance of the slit  86 . 
   As shown in  FIGS. 15-19 , two locking claws  89  are formed at positions rearward from the slits  86  and a little inward from the slits  86  on each of the upper and lower surfaces of the male metal shell  80 . Each locking claw  89  is raised to extend rearward and inward from the respective surface of the male metal shell  80 , as shown in FIG.  16 . Locking holes  76  are formed on the upper and lower surfaces of the inner housing  61  at positions corresponding to the locking claws  89  for engaging the locking claws  89 . 
   A detector  90  is installed inside the rear of the dome  37  of the female housing  30 . The detector  90  is made of synthetic resin and is formed separately from the female housing  30 . As shown in  FIG. 28 , a rectangular frame-shaped body  91  of the detector  90  is disposed between the right and left side-walls of the dome  37 . A front frame  91 A of the body  91  is formed higher than other portions thereof. An edge of the inner side of a rear frame  91 B of the body  91  of the detector  90  opens to the jig insertion opening  44 A. 
   A sliding plate  92  projects from the right and left outer side surfaces of the body  91 . A longitudinal guide groove  41  is formed on the inner surface of the right and left side-walls of the dome  37  for slidably receiving the sliding plate  92 . As shown in  FIG. 25 , the sliding plate  92  fits in the guide groove  41 , and the pressing portion  44  of the locking arm  40  fits in the body  91  to move the sliding plate  92  longitudinally under the guide of the guide groove  41 . A stepped slide prevention portion  93  is formed on a rear surface of the body  91 . 
   An upper surface of a rear frame  91 B of the body  91  is lower than the flange  46  that projects from the rear end of the pressing portion  44  of the locking arm  40  when the locking arm  40  is in a natural state and when the detector  90  is inside the rear of the dome  37  of the female housing  30 , as shown in FIG.  31 . As shown in  FIG. 25 , an inner surface of the rear frame  91 B is concave and corresponds to the configuration of the flange  46  of the pressing portion  44 . A detection projection  94  is formed at the lower end of the widthwise center of the inner surface of the rear frame  91 B. The detection projection  94  can enter the groove  41  on the lower surface of the locking arm  40 , when the locking arm  40  is in a natural state. 
   A projection  95  is formed at approximately the longitudinal center of the sliding plate  92  of the detector  90 . A locking step  104  is formed at the entrance of the guide groove  103  and can lock the projection  95 . 
   Two locking pieces  96  project forward from the right and left ends of the front frame  91 A of the body  91 . More specifically, as shown in  FIG. 30 , an upper surface of each of the locking pieces  96  is flush with the sliding plate  92 . Each of the locking pieces  96  is divided widthwise into an outer side and an inner side. The inner side of each locking piece  96  is longer and thicker than the outer side thereof. 
   A receiving wall  105  projects in from the lower end of the right and left walls of the dome  37 . The outer side of the locking piece  96  is slidable on an upper surface of the receiving wall  105 . However, an outer surface of the inner side of the locking piece  96  can slide along an inward projected surface of the receiving wall  105 . 
   A striking portion  97  is formed at the front end of the outer side of the locking piece  96  and has the shape of a downward hook. As shown in  FIG. 27 , a stopper  106  is formed on the upper surface of the receiving wall  105 . A front surface of the stopper  106  is erect, whereas a rear surface  106 A is tapered. The striking portion  97  is locked to the rear surface of the stopper  106 . The striking portion  97  has a tapered locking surface that forms a semi-locking construction with the tapered surface  106 A of the stopper  106 . 
   A hook  98  is disposed at the front end of the inner side of the locking piece  96  and is lower than the striking portion  97 . A release portion  108  is formed outward from the guide wall  71  of the male housing  20 . The release portion  108  functions to lift the hook  98  of the locking piece  96 , while the release portion  108  scoops the hook  98 . A front surface of the release portion  108  is tapered, whereas a rear surface thereof is erect. The hook  98  is locked to the rear surface of the release portion  108 . As shown in  FIG. 33 , the hook  98  has a gently tapered surface  98 A. The corner of the rear surface of the release portion  108  is rounded to form a semi-locking construction in combination of the tapered surface  98 A of the hook  98  and the rounded corner of the rear surface of the release portion  108 . 
   In the above-described construction, the sliding plate  92  is fit into the guide groove  103  and the detector  90  is pressed forward. The striking portion  97  of the locking piece  96  then strikes the stopper  106 , as shown in FIG.  25 . Thereafter the projection  165  of the sliding plate  92  is locked to the locking step  104  of the guide groove  103 . As a result, the detector  90  is held in a wait position without being pressed. As shown in  FIG. 31 , the detection projection  94  is at the wait position rearward from the rear end of the locking arm  40 . Thus the rear end of the locking arm  40  can pivotally deform into the flexing space  48 . 
   The female connector F is assembled further by inserting the female metal shell  50  into the insertion space  34  between the inner housing  31  and the outer housing  32  of the female housing  30  from the rear, as shown with arrows of  FIGS. 4 and 5 . Forward movement of the female metal shell  50  in the insertion space  34  presses the rib  35  into the corresponding slit  56 . The rounded step  56 B of the guide  56 A guides the rib  35  into the slit  56  even if the female metal shell  50  is slightly misaligned with the female housing  30 . Thus the female metal shell  50  is pressed straight into the insertion space  34 . 
   The locking claw  58  reaches the locking groove  48  when the rib  35  strikes the rear end of the slit  56 . Thus, as shown in  FIG. 13 , the locking claw  58  elastically returns to its original state and is locked to the locking groove  48 . Accordingly, the female metal shell  50  is mounted on the periphery of the inner housing  31  with the rear end of the inner housing  31  approximately at the longitudinal center of the female metal shell  50 , and so that the female metal shell  50  cannot slip off the inner housing  31 . At this time, the front end of the female metal shell  50 , including the contact plates  55 , projects forward from the front end of the outer housing  32 . 
   As shown in  FIG. 13 , the folded portion  57  at the front end of the female metal shell  50  contacts the peripheral surface of the inner housing  31  to form a flexing space  57 A that permits the contact plate  55  to deform elastically inward. 
   The female terminal fittings  20  are fixed to the ends of the shielding electric wire  10  then are inserted into the cavities  33  of the female housing  30  from the rear and are locked by the respective lances  33 A. Thus, the metal pipe  15  fit on the periphery of the braided wire  13  disposed at the end of each shielding electric wire  10  is elastically sandwiched elastically between the upper and lower contact pieces  54 . Thereafter a waterproof rubber plug  110  is fit inside the rear end of the outer housing  32 . A rubber plug hold-down member  112  prevents the waterproof rubber plug  110  from slipping off the outer housing  32 . A seal ring  114  is fit on the periphery of the outer housing  32  at its front end to seal the gap between the outer housing  32  and the mating male housing  60 . 
   The male metal shell  80  then is inserted from the rear into the insertion space  68  between the inner housing  61  and the outer housing  62  of the male housing  60 , as shown with arrows of  FIGS. 14 and 15 . The connection ribs  69  are pressed into the corresponding slits  86  due to the forward movement of the male metal shell  80 . The rounded step  87 A of the guide  87  guides the ribs  69  into the slits  86  even if the male metal shell  80  is slightly misaligned with the male housing  60 . Thus the male metal shell  80  is pressed straight into the insertion space  68 . 
   The locking claws  89  move forward along the escape groove  77  and elastically deforming a little. The locking claws  89  then reach the locking hole  76  when the rib  69  strikes the rear end of the slit  86 . Thus, as shown in  FIGS. 1 and 21 , each locking claw  89  then elastically returns to its original state and is locked to the locking hole  76 . Accordingly, the male metal shell  80  is mounted on the periphery of the inner housing  61  and projects from the front and rear ends of the inner housing  61 . Additionally, the male metal shell  80  cannot slip off the inner housing  61 . 
   Because the male metal shell  80  is formed long sideways in section by press-molding one metal plate, there is a potential that it will deform and open near the widthwise center on its upper and lower surfaces. Thus, there is a possibility that the front end of the male metal shell  80  projected into the small hood  66  of the outer housing  62  remains opened because there is a clearance near the front end of the male metal shell  80 . However the opening prevention ribs  79  formed on the inner peripheral surface of the small hood  66  hold down the front end of the male metal shell  80 , thus keeping the male metal shell  80  in a closed state. 
   The male terminal fittings  25  fixed to the ends of the shielding electric wire  10  then are inserted into the cavities  63  of the male housing  60  from the rear and are locked by the lances  63 A. The metal pipe  15  on the periphery of the braided wire  13  at the end of each shielding electric wire  10  is sandwiched elastically between the upper and lower contact pieces  84 . Thereafter a waterproof rubber plug  78  is fitted inside the rear end of the outer housing  62 . A rubber plug hold-down member  78 A prevents the waterproof rubber plug  78  from slipping off the outer housing  62 . 
   The female connector F and the male connector M then are opposed to each other, as shown in  FIG. 1 , and are moved toward each other. As a result, the front end of the locking arm  40  rides across the locking projection  70  of the male housing  20 , as shown in FIG.  29 . Thus, the female housing  30  and the male housing  20  are fit together, with the rear side of the locking arm  40  pivotally deforming into the flexing space  48 . The locking arm  40  returns elastically toward its original state and is locked to the locking projection  70 , as shown in  FIG. 2 , when the male and female connectors M and F are normally fit together. 
   At this time, as shown in  FIGS. 30 and 33 , the release portion  108  of the male housing  20  slips under the hook  98  of the locking piece  96  of the detector  90 , and lifts the hook  98 . Consequently the striking portion  97  escapes up from the stopper  106 , and the restriction of the pressing of the detector  90  is released. 
   Meanwhile, the female and male terminal fittings  20  and  25  are connected together, and projected ends of the male metal shell  80  and that of the female metal shell  50  are connected. At this time, there is an increase in the resistance in fitting the female terminal fittings  20  and the male terminal fittings  25  together. Thus there is a possibility that the operation of fitting the female housing  30  and the male housing  20  together is suspended, and the female and male housings  30  and  20  are kept in a semi-fit-on state. 
   The rear end of the locking arm  40  is still pivotally deformed in the flexing space  48  in the semi-fit-on state. Thus, the detection projection  94  strikes the upper portion of the groove  41  disposed on the rear end of the locking arm  40 . As a result, the detector  90  cannot be pressed, and it is detected that the female housing  30  and the male housing  20  are still in the semi-fit-on state. Thereafter the operation of fitting the female housing  30  and the male housing  20  together is continued. 
   The front end of the locking arm  40  rides across the locking projection  70  of the male housing  20  when the male and female housings  20  and  30  have been fit together normally. Thus as shown in  FIG. 31 , the locking arm  40  returns elastically to its original state, and the locking projection  70  is fit in the locking hole  43 . Accordingly, the male and female housings  20  and  30  are locked together in a normal fit-on state. 
   The locking arm  40  returns to the original position when the male and female housings  20  and  30  reach the normal fit-on state, and thus the rear end of the locking arm  40  escapes up from the flexing space  48 . The detector  90  then is pressed forward, and the detection projection  94  advances into the groove  41  of the locking arm  40 . The detector  90  then is pressed into the detection position, as shown in FIG.  33 . As a result, the striking portion  97  and the hook  98  are locked to the rear surfaces of the stopper  106  and the release portion  108  respectively. Additionally, the locking piece  96  returns elastically to its original state, and the detector  160  is held in a return-prevented state. 
   Accordingly, it is detected that the male and female housings  20  and  30  have been fit together normally. Further the detection projection  94  receives the pressing portion  44  of the locking arm  40  to prevent the operation of pressing the locking arm  40 . In this manner, the locking arm  40  is locked doubly. 
   It is noteworthy that when the detector  90  is held at the detection position, as shown in  FIG. 31 , the edge of the inner side of the rear frame  91 B of the body  91  of the detector  90  is mostly hidden under the flange  46  that projects from the rear end of the pressing portion  44  of the locking arm  40 . Thus, fingers or foreign matter cannot catch by the rear frame  91 B and the detector  90  cannot be returned accidentally to the wait position. 
   The front end of the male metal shell  80  fits on the periphery of the front end of the female metal shell  50  during the connection process. At this time, the opening prevention rib  79  holds the front end of the male metal shell  80  in the normal closed state. Thus the female metal shell  50  and the male metal shell are fitted on each other smoothly. More specifically, as shown in  FIG. 2 , the front end of the male metal shell  80  strikes the contact projection  56  of the contact plate  55  formed on the female metal shell  50 . When the female metal shell  50  and the male metal shell are fit on each other a predetermined amount, the contact plate  55  elastically deforms in the flexing space  57 A, the contact projection  56  is pressed strongly against the inner peripheral surface of the male metal shell  80  by the restoring elastic force of the contact plate  55 . 
   In this state, the inner housing  31  of the female housing  30  fits in the fit-in concavity  65  of the outer housing  62  of the male housing  60 . Thus, the female terminal fitting  20  and the male terminal fitting  25  are connected to each other. At the same time, the front end of the male metal shell  80  fits on the periphery of the front end of the female metal shell  50 , and the contact plates  55  of the female metal shell  50  contact the inner peripheral surface of the male metal shell  80  elastically. As a result, the female metal shell  50  and the male metal shell  80  electrically connect and cover the connection between the female terminal fitting  20  and the male terminal fitting  25  and the metal pipes mounted on the end of the shielding electric wires  10 . 
   As shown in  FIG. 30 , the release portion  108  of the male housing  20  slips under the hook  98  of the locking piece  96  at the last stage of the operation of fitting the male and female housings  20  and  30  together. Thus, the front side of the locking piece  96  is deformed elastically, and the striking portion  97  escapes up from the stopper  106 . Accordingly, the restriction of the pressing of the detector  90  is released. 
   The detector  90  can be pressed into the wait position, with the detection projection  94  entering the groove  41  of the locking arm  40 , if the female housing  30  and the male housing  20  have been fit together normally and if the locking arm  40  has returned to its original position. The operation of pressing the detector  90  forward is prevented, when the inner surface of the rear frame  91 B of the body  91  strikes the rear surface of the pressing portion  44  of the locking arm  40 . At this time, the locking piece  96  returns elastically to its original state. Further the striking portion  97  and the hook  98  are locked to the rear surface of the stopper  106  and to the rear surface of the release portion  108  respectively. Thus, the detector  90  is held at a detection position in a removal-prevented state. 
   The edge of the inner side of the rear frame  91 B of the body  91  of the detector  90  at the detection position is hidden under the flange  46  projected from the rear end of the pressing portion  44  of the locking arm  40 , as shown in FIG.  32 . 
   The detector  90  is mounted on the female housing  30  at the wait position. As described previously, the rear end of the locking arm  40  at the wait position can pivotally deform into the flexing space  48 , while the detection projection  94  is rearward from the rear end of the locking arm  40 . 
   The slit  56  for receiving the rib  35  of the female metal shell  50  and the slit  86  for receiving the rib  69  of the male metal shell  80  are offset from each other in the widthwise direction of the female metal shell  50  and the male metal shell  80  so that the slits  56  and  86  do not align. Therefore, as shown in  FIG. 14 , the front end of the female metal shell  50  closes the slit  86 , and the front end of the male metal shell  80  closes the slit  56  when the front ends of the female metal shell  50  and the male metal shell  80  are fit on each other. Accordingly, the whole region of the front end of the female metal shell  50  is covered with the male metal shell  80 , and the whole region of the front end of the male metal shell  80  is covered with the female metal shell  50 . Thus, shielding performance is enhanced. 
   The guide  57  is formed at the entrance of the slit  56  of the female metal shell  50 , and the guide  87  is formed at the entrance of the slit  86  of the male metal shell  80 . Thus the metal shells  50  and  80  can be fit easily on the peripheries of the inner housings  31  and  61  respectively. 
   The metal shells  50  and  80  are constructed of two identical split shells  51  and  81  in the form of shallow channels. The two split shells are connected to each other by caulking opposed right and left side surfaces to each other. Therefore, the female and male metal shells  50  and  80  will not open and keep their specified configuration. 
   The split shells  51  and  81  are smaller than the metal shell composed of one plate. Thus it is possible to adopt progressive press dies and to reduce the number of dies. Therefore it is possible to reduce the manufacturing cost. 
   The contact plate  55  is interposed between the female metal shell  50  and the male metal shell  80 . Thus, the contact plate  55  achieves secure contact pressure and stabilizes an electrical connection between the female metal shell  50  and the male metal shell  80 . Accordingly, the shielding function is enhanced. 
   The folded portion  57  at the front end of the female metal shell  50  contacts the peripheral surface of the inner housing  31  and forms the flexing space  55 A. The contact plate  55  deforms elastically into the flexing space  55 A when the female and male metal shells  50  and  80  have been fit together. The contact plate  55  contacts the inner surface of the male metal shell  80  due to the restoring elastic force of the contact plate  55 . 
   Although the construction of the embodiment is simple, the contact plate  55  achieves appropriate flexing and a high contact pressure while reducing the resistance in fitting the female metal shell  50  and the male metal shell  80  together. Further, the strength of the front end of the female metal shell  50  is increased. 
   The male and female housings  20  and  30  can be separated for maintenance by inserting the jig J into the jig insertion opening  44 A, as shown in FIG.  38 . The jig J then is pulled rearward, with the jig J catching the valley of the rear frame  91 B of the detector  90 . As a result, the detector  90  is returned to the wait position, with the semi-locking between the locking piece  96  and the stopper  106  and the release portion  108  being released. 
   The locking arm  40  is pivotally deformable and is unlocked by forcibly pivotally deforming it. Thus it is possible to unlock the male and female housings  20  and  30  from each other by pulling them in a move-away direction. 
   As described above, when the detector  90  is pressed into the detection position, the rear frame  91 B is mostly hidden under the flange  46  that projects from the pressing portion  44  of the locking arm  40 . Thus it is possible to prevent fingers or foreign matters from being caught by the rear frame  91 B. When the detector  90  is returned intentionally to the wait position, the jig J is inserted into the jig insertion opening  44 A to catch a part of the rear frame  91 B with the jig J. 
   Thus it is possible to prevent the detector  90  from being returned accidentally and the male and female housings  20  and  30  will not be separated unintentionally. 
   An alternate female metal shell  50   a  is shown in FIG.  34 . Dovetail projections  52   a  dovetail recesses  53   a  are formed in opposed edges of the female metal shell  50   a  to connect the edges thereof. In all other respects, the female metal shell  50   a  is the same as the female metal shell  50 . The male shell can have similar dovetail projections and dovetail recesses. 
   An alternate female housing  30 A is shown in  FIGS. 35 and 36 . The female housing  30 A has locking grooves  40 A formed on the inner housing  31  for receiving the locking claws  58 . The locking grooves  40 A are open at the front side. As shown in  FIG. 36 , each locking groove  40 A is disposed between the adjacent cavities  33 A. The locking grooves  40 A for engaging the locking claws  58  utilize the dead space between the adjacent cavities  33 . This differs from the conventional art of forming the locking portion on the outer wall of the cavity. Thus, it is unnecessary to thicken the peripheral wall of the outer housing  62 , and the female housing  30  is compact radially. 
   The invention is not limited to the embodiment described above with reference to the drawings. For example, the following embodiments are included in the technical scope of the present invention. Further, various modifications of the embodiments can be made without departing from the spirit and scope of the present invention. 
   The metal shell is not limited to the split type described in the embodiment, but may be constructed of one plate. 
   The present invention is applicable to a non-waterproof shielding connector and a shielding connector that is directly connected to equipment. 
   The locking hole is formed in the region of the bottom wall of the flexing space against which the lance does not strike. However, the locking hole may be extended in such a way that the lance strikes a part of the locking hole. In this case, the locking hole, namely, the locking claw can be widely formed to enhance the force of locking the metal shell. 
   The metal shell is applicable to a connector in which the male housing has the locking arm and the detector. 
   The detector is not limited to the shielding connector, but is applicable to other connectors for detecting connection between the male housing and the female housing.