Patent Publication Number: US-7214090-B2

Title: Connector device

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a connector device in with male and female connectors that are connected separately. 
   2. Description of the Related Art 
   Japanese Unexamined Patent Publication No. 2001-283975 discloses a known electronic control unit (ECU) with connectors on side surfaces of an ECU casing. The connectors are mated with connectors at ends of a wiring harness. The ECU connector has a lock and the harness-side connector has a resilient lock arm that engages the lock for locking the connectors together. 
   A force may act to separate the locked connectors. Such a force might be generated, for example, if the wiring harness drawn out from the harness-side connector is pulled inadvertently. An excessive force of this type could fracture the lock or other parts of the locking mechanism. The device-side connector could be integral with the ECU casing. Thus, a lock failure could require replacement of the entire ECU casing and could require considerable labor and cost for repair. 
   The invention was developed in view of the above problem and an object thereof is to improve operational efficiency and to allow an easier exchange of connectors. 
   SUMMARY OF THE INVENTION 
   The invention relates to a connector device with a fixed connector and a movable connector. The fixed connector is mounted integrally or unitarily to another member. The other movable connector is connectable with and separable from the fixed connector. The two connectors are locked together by the engagement of locks provided therein. The fracture strength of the lock of the fixed connector exceeds the fracture strength of the movable connector. 
   A force could act to separate the locked connectors, and could be sufficiently great to cause a fracture, such as a shear fracture. The fracture strength refers to strength against such a fracture. The fracture strength can be calculated based on the material strength and the shear area of the lock. Specifically, the fracture strength can be calculated as a product of the material shear strength and the shear area. The fracture strength also can be calculated by multiplying this product by a coefficient based on the shape characteristic of the lock:
 
fracture strength [N]=material shear strength [N/mm 2 ]×shear area [mm 2 ]×coefficient
 
   An excessive force that acts in a direction to separate the two locked connectors will fracture the lock of the movable connector first and will cancel the locked state. However, the lock of the fixed connector will not fracture. The movable connector can be exchanged relatively easily. Thus, repairs can be made easily and inexpensively. 
   The movable connector preferably includes a resiliently deformable lock arm that is formed with a lock. The fixed connector preferably includes an engaging portion that is engageable with the lock of the lock arm. The fracture strength of the engaging portion of the fixed connector is larger than the fracture strength of the lock of the movable connector. 
   The connectors are locked together by engaging the lock of the lock arm with the engaging portion. An excessive force to separate the locked connectors will fracture the lock of the lock arm of the movable connector to cancel the locked state, but the engaging portion will not fracture. 
   The lock arm preferably has a three-point supporting construction. 
   At least one rib is formed at a side of the engaging portion of the fixed connector and extends substantially in a connecting direction. The rib is fittable into a guiding groove in the movable connector and is adapted to prevent a forcible connection. A side surface of the engaging portion preferably is coupled to the rib. Thus, the fracture strength of the engaging portion is increased without taking up extra space. The projecting distance of the rib preferably exceeds the projecting distance of the engaging portion. 
   The fracture strength of the lock of the fixed connector preferably is at least about 1.3 times larger, more preferably at least about 1.5 times larger, most preferably at least about 1.7 times larger than the fracture strength of the lock of the movable connector. 
   Ribs and grooves preferably are provided on the connectors to avoid an improper connection. 
   A cover preferably is mounted to the movable connector to at least partly cover a wire draw out portion thereof. 
   These and other features of the invention will become more apparent upon reading the following detailed description and accompanying drawings. It should be understood that even though embodiments are described separately, single features may be combined to additional embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of an ECU casing and a side view of female connectors according to a first embodiment of the invention. 
       FIG. 2  is a section showing a state before the female connector is connected with a male connector. 
       FIG. 3  is a perspective view showing the state before the female connector is connected with the male connector. 
       FIG. 4  is a front view of the male connector. 
       FIG. 5  is a rear view of the female housing. 
       FIG. 6  is a section showing a state where the female connector is connected with the male connector. 
       FIG. 7  is a perspective view showing a part where an engaging portion is formed. 
       FIG. 8  is a front view of a male connector according to a second embodiment. 
       FIG. 9  is a section along  9 — 9  of  FIG. 8 . 
       FIG. 10  is a perspective view showing a part where an engaging portion is formed. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A connector device according to a first embodiment of the invention is illustrated in  FIGS. 1 to 7 . The connector device includes male and female connectors  10  and  20  that are connectable with one another. In the following, mating sides of connectors  10 ,  20  are referred to as the front. 
   As shown in  FIGS. 1 and 2 , three male connectors  10  are aligned on one surface of an ECU (electronic control unit) casing C that is a vertically long flat box. Several such ECU casings preferably are arranged side-by-side. Female connectors  20  are connectable with the respective male connectors  10  along a connecting direction CD. 
   The male connector  10  is a circuit board connector to be mounted on a printed circuit board K. The male connector  10  has a male housing  11  that is made of a synthetic resin, and male terminal fittings  12  are mounted in the male housing  11 . As also shown in  FIGS. 3 and 4 , the male housing  11  is wide and has a fitting recess  13  in its front mating surface. Terminal insertion holes  15  are formed at upper and lower stages in a base wall  14  at the back of the fitting recess  13 . The terminal insertion holes  15  at the upper stage are offset from those at the lower stage. 
   Tab-shaped ends of the male terminal fittings  12  are inserted through the corresponding terminal insertion holes  15  and project into the fitting recess  13  in alignment. The opposite ends of the male terminal fittings  12  project back from the base wall  14  and are bent down at substantially right angles at specified positions. The rear ends of the male terminal fittings  12  then are bent back at substantially right angles to define connecting portions  12 A. 
   The male connector  10  is to be placed at a specified position on the board K with the fitting recess  13  faced outward. Fixing members  16  are mounted on opposite side surfaces of the housing  11  and are fixed to the circuit board K by soldering, (ultrasonic) welding, press-fitting, insulation displacement mounting or the like. The connecting portions  12 A of the male terminal fittings  12  are soldered, welded, press-fitted or otherwise connected to corresponding conductor paths on the board K. 
   The board K having the male connectors  10  mounted thereon is accommodated into the ECU casing C. Accordingly, the respective male connectors  10  are fit in window holes Ca in a surface of the casing C. 
   The female connector  20  includes a female housing  21  made e.g. of a synthetic resin. The female housing  21  is a wide block that is fittable into the fitting recess  13  of the male housing  11 , as shown in  FIGS. 3 and 5 . Cavities  22  are formed at upper and lower stages in the female housing  21  for accommodating female terminal fittings  30 . The cavities  22  are arranged to align with the male terminal fittings  12  of the male connector  10 . Thus, the cavities  22  at the upper stage are offset from those at the lower stage. 
   Each female terminal fitting  30  has a rectangular tubular main portion  31  with a resilient contact piece  32  (see  FIG. 6 ) for contacting the mating male terminal fitting  12 . A barrel is provided behind the main portion  31  for crimped connection to an end of a wire W. 
   The female terminal fitting  30  is inserted into the cavity  22  from behind, and is locked at a proper position by a locking portion  23  at the bottom wall of the cavity  22 . The female terminal fitting  30  then is locked redundantly in the cavity  22  by a retainer  25  and the wire W is drawn out backward through the rear entrance of the cavity  22 . 
   A cover  35  made e.g. of a synthetic resin is mounted on the rear surface of the female housing  21 . The cover  35  accommodates the wires W drawn out through the rear surface of the female housing  21  together as a wire group Wa and introduces the wires W in a specified direction through a wire lead-out opening  36 . The lead-out opening may have a tubular shape or at least one lateral guide projection. 
   A lock arm  40  is provided in substantially the widthwise middle of the upper surface of the female housing  21 . The lock arm  40  has an arm main body  41  that projects up from the front edge of the upper surface of the female housing  21  and then extends back. An unlocking portion  42  extends substantially in a width direction at the rear end of the arm main body  41 . Opposite ends of the unlocking portion  42  are coupled to protection walls  43  that project from the upper surface of the female housing  21 . Thus, the lock arm  40  has a three-point supporting construction and is resiliently displaceable substantially along a vertical direction that is substantially normal to the connecting direction CD. A lock  45  is formed on the arm main body  41  of the lock arm  40 . A substantially upright locking surface  45 A is formed at the rear of the lock  45  with respect to a connecting direction CD of the two connectors  10 ,  20  and is substantially normal to the connecting direction CD. A slanted guiding surface  45 B is formed at the front of the lock  45 . 
   An engaging portion  47  is formed near the front edge in a widthwise middle of the ceiling surface of the fitting recess  13  of the male housing  11  and is engageable with the lock  45  of the lock arm  40 . A substantially upright locking surface  47 A is formed on the rear of the engaging portion  47  with respect to the connecting direction CD of the two connectors  10 ,  20  and is substantially normal to the connecting direction CD. A slanted guiding surface  47 B is formed on the front of the engaging portion  47 . 
   As shown in  FIG. 6 , the locking surface  45 A of the lock  45  of the lock arm  40  faces the locking surface  47 A of the engaging portion  47  when the female connector  20  is fit properly into the male connector  10 . Thus, the male and female connectors  10 ,  20  are locked together. 
   An excessive force may act to separate the connectors  10 ,  20  from the locked state shown in  FIG. 6 . This force acts after the locking surfaces  45 A,  47 A of the lock  45  and the engaging portion  47  are in contact. Thus, the lock  45  and the engaging portion  47  receive a shear force and could experience a fracture, such as a shear fracture. The lock  45  and the engaging portion  47  must be sufficiently strong to resist the fracture. 
   Accordingly, the fracture strength of the engaging portion  47  of the male connector  10  is made larger than the fracture strength of the lock  45  of the lock arm  40  of the female connector  20 . 
   The fracture strengths of the lock  45  and the engaging portion  47  can be calculated based on the shear strengths of the materials and the shear areas thereof. Specifically, fracture strengths can be calculated as products of the material shear strengths and the shear areas or by multiplying these products by coefficients based on the shape characteristics of the lock  45  and the engaging portion  47 :
 
fracture strength [N]=material shear strength [N/mm 2 ]×shear area [mm 2 ]×coefficient
 
   For example, the fracture strength of the lock  45  of the female connector  20  could take a value of up to 155 N. The fracture strength of the engaging portion  47  of the male connector  10  then could be 200 N or larger (or more than about 1.3 times larger, more preferably more than about 1.5 times larger, most preferably more than about 1.7 times larger). 
   The male housing  11  has ribs  50  that extend forward and back along the connecting direction CD to prevent forcible connection of the connectors  10 ,  20  in an improper orientation. Three ribs  50  are on the ceiling surface of the fitting recess  13 , and one rib  50  is on the bottom surface of the fitting recess  13 . Two of the ribs  50  on the ceiling surface are spaced slightly from the opposite sides of the engaging portion  47 . The ribs extend from the front edge of the fitting recess  13  to the back surface. The ribs  50  at lateral sides of the engaging portion  47  (as shown e.g. in  FIG. 7 ) guide an engagement thereof and/or protect the engaging portion  47  against damage. 
   The female housing  21  has four guiding grooves  52  that extend forward and back along the connecting direction CD, as shown in  FIG. 3 . Two guiding grooves  52  are on the upper surface of the female housing  21  at opposite sides of the lock arm  40  and a third guiding groove  52  is further to the left on the ceiling surface when viewed from the front. A fourth guiding groove  52  is to the right on the bottom surface of the female housing  21 . The ribs  50  fit closely in the guiding grooves  52 . 
   Female terminal fittings  30  are inserted in the cavities  22  of the female housing  21  to start the assembly process. The retainer  25  then is pushed to a position for redundantly locking the female terminal fittings  30 . Wires W drawn out through the rear surface of the female housing  21  are bundled as shown in  FIG. 2 . The cover  35  then is mounted on the rear of the female housing  21 , and the bundled wire group Wa is drawn out through the wire lead-out opening  36 . 
   The female connectors  20  having the covers  35  mounted thereon are connected along the connecting direction CD with the mating male connectors  10  in the windows Ca of the ECU casings C, as shown by the arrow of  FIG. 2 . As a result, the guiding surface  47 B of the engaging portion  47  contacts the guiding surface  45 B of the lock  45  and deforms the lock arm  40 . The lock arm  40  is restored resiliently after sufficient pushing so that the locking surface  45 A of the lock  45  engages the locking surface  47 A of the engaging portion  47 , as shown in  FIG. 6 . Thus, the male and female connectors  10 ,  20  are locked together and the corresponding male and female terminal fittings  12 ,  30  are connected properly. 
   The wire group Wa may be pulled, as shown by the arrow of  FIG. 6 , to generate a force that acts to separate the connectors  10 ,  20  while the connectors  10 ,  20  are locked together. Contact of the locking surfaces  45 A,  47 A of the lock  45  and the engaging portion  47  will hold the connectors  10 ,  20  together if the separation forces are low. However, the lock  45  and the engaging portion  47  may fracture if the force is excessive. 
   Accordingly, the engaging portion  47  of the male connector  10  is formed to have a fracture strength that exceeds the fracture strength of the lock  45  of the lock arm  40 . Thus, the lock  45  of the lock arm  40  experiences a fracture first. The locked state is canceled when the lock fails and the female connector  20  can be pulled from the male connector  10 . Thus, the engaging portion  47  of the mating male connector  10  will not fracture. The female housing  21  can be exchanged for a housing with a functioning locking mechanism. 
   As described above, an excessive force will fracture the lock  45  of the female connector  20  first to cancel the locked state. Thus, the engaging portion  47  of the male connector  10  in the ECU casing will not fracture. 
   A fracture of the engaging portion  47  of the male connector  10  would require a disconnection of the soldered connection to the circuit board K, an exchange the male housing  11 , and either a reattachment of the new male housing  11  to the board K or the preparation of a new board K. The entire ECU casing also might need replacement. Such exchanges take labor and cost. However, only the female housing  21  needs to be replaced if the lock  45  of the lock arm  40  of the female connector  20  is fractured. The locking mechanism can be repaired easily and inexpensively repaired merely by a simple operation of reinserting the female terminal fittings  30 . 
     FIGS. 8 to 10  show a second embodiment of the invention. The engaging portion  47  of the first embodiment is spaced from the ribs  50 . However, the engaging portion  55  of the second embodiment is coupled unitarily to the ribs  50  at the opposite left and right ends. The other construction is the same as or similar to the first embodiment. These similar parts are identified by the same reference numerals, but are not described again. 
   The engaging portion  55  of the second embodiment is wider than the engaging portion  47  of the first embodiment to increase the shear area. Additionally, the engaging portion  55  is coupled unitarily with the ribs  50  to provide a high rigidity and increased fracture strength. Accordingly, an excessive force that acts in a direction to separate the two locked connectors  10 ,  20  will cause the lock  45  of the lock arm  40  to fracture first, thereby canceling the locked state. Thus, the engaging portion  55  of the male connector  10  is even less likely to fracture. 
   The widening of the engaging portion  55  eliminates only the clearances for the ribs  50 , i.e. dead spaces. Thus, extra space is not needed for this increase in the fracture strength of the engaging portion  55 , and the male housing  11  is not enlarged. The projecting height of the ribs  50  preferably exceeds the projecting height of the engaging portion  55 . 
   The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are also embraced by the technical scope of the present invention as defined by the claims. Beside the following embodiments, various changes can be made without departing from the scope and spirit of the present invention as defined by the claims. 
   Numerical values of the fracture strength shown in the foregoing embodiment are merely examples and can be suitably selected according to using conditions and the like. 
   The fixed connector can have a housing that is integral or unitary with a casing of the device. 
   The invention is applicable to a case where the fixed connector is a female connector and the movable connector is a male connector. 
   The cover on the female connector can be omitted. 
   The invention is applicable to all kinds of connectors, in particular those mounted to other electric or electronic devices, such as junction boxes, dashboard panels, etc.