Abstract:
An electrical connector has a cover ( 20 ) attached by a center latching arm ( 15 ) and two side latching arms ( 26 ). The rigidity of a center arm ( 15 ) is decreased, and the rigidity of side arms ( 26 ) is increased, by specifying the material from which a housing ( 10 ) and a cover ( 20 ) are formed. Neither of the two side edges of the center arm ( 15 ) join with other parts. This decreases the rigidity of the center arm ( 15 ). An edge of each side arm ( 26 ) is joined to an L-shaped circumference wall ( 27 ). As a result, the rigidity of the side arms ( 26 ) is high. By this means, the release operation of the center arm ( 15 ) is improved, and the side arms ( 26 ) are not vulnerable to accidental released by a pull on the electric wires ( 12 ).

Description:
TECHNICAL FIELD 
     The present invention relates to an electric connector provided with a cover. 
     BACKGROUND OF THE INVENTION 
     A conventional example of a connector provided with a cover is described in JP 10-112347. This connector comprises a housing and a cover. Terminal fittings are inserted into the housing, and electric wires which are fixed to the terminal fittings are guided outwards via an electric wire guiding face provided on a rear face of the housing. The cover is attached to the housing so as to cover the electric wire guiding face. The cover is block-like, one side thereof being joined to the housing by a hinge. The remaining three sides have resilient latching arms protruding therefrom. When the cover is attached to the housing, these latching arms engage with latching protrusions which protrude from the housing, these three arms latching the cover to the housing in an attached state. 
     In this prior connector, the cover is removed from the housing by bending the latching arms and separating them from the protrusions. However, it is difficult to bend all three arms at the same time. In order to deal with this problem a configuration is possible whereby the cover is a component separate from the housing and is not joined thereto by a hinge. In this configuration, the cover is inclined towards the housing with only a centre latching arm being in a bent state. A latching arm is located at each side of the centre arm. The inclining operation causes one of these two latching arms to separate from its protrusion. Then, the cover is inclined in the opposite direction. thereby separating the other arm from its protrusion. In this manner. all three latching arms are separated from their respective protrusions, and the cover can be removed from the housing. 
     It is desirable to decrease the rigidity of the centre latching arm so as to improve the ease with which it can be bent in a releasing direction. Furthermore, the rigidity of the side latching arms should be increased to deal with the case where an external force causes the electric wires to interfere with these side arms and thereby move them in the releasing direction. 
     However, in the prior example, all of the three latching arms are formed in a unified manner with the cover. As a result, if the rigidity of one of these arms is increased or decreased by changing the material used for the cover, the rigidity of the other arms also increases or decreases. Consequently, if the rigidity of the centre arm is decreased so as to improve its releasing operability, the side arms are more easily moved in the releasing direction when the electric wires interfere therewith. Conversely, if the rigidity of the side arms is increased so as to prevent them from being moved in the releasing direction by the electric wires, the releasing operability of the centre arm worsens. 
     The present invention has been developed after taking the above problem into consideration, and aims to present a connector provided with a cover wherein the latch release operation of the centre arm is improved, and wherein the side arms are not released from their latched state as a result of interference from the electric wires. 
     SUMMARY OF THE INVENTION 
     According to the invention there is provided an electrical connector comprising a housing having an exit face for wires. and a cover for said exit face, the housing and cover having three mutually engageable resilient latching means, said latching means comprising a centre latching arm and two side latching arms, characterised in that said centre latching arm is a cantilever, and each of said side latching arms are joined along one side edge to a respective portion of one of said housing and cover. the other side edge being free. 
     Such a cover/housing combination permits good flexibility of the centre arm, but allows the side arms to be rather stiff since they are not cantilevers. 
     In a preferred embodiment the side arms are provided on the cover and attached along one edge to a wall of the cover, substantially at right angles. This makes the side arms comparatively stiff. 
     The centre arm preferably latches within the cover, in an aperture of the wall thereof. The cover is preferably symmetrical and the side arms identical but in mirror image. 
     The centre arm may have an outwardly directed latching protrusion, whereas the side arms may have respective inwardly directed protrusions. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     One feature of the invention will be apparent from the following description of a preferred embodiment shown by way of example only in the accompanying drawings in which 
     FIG. 1 is a partially cut-away diagonal view of a housing of an embodiment of the invention showing a cover in a removed state therefrom. 
     FIG. 2 is a vertical cross-sectional view showing the cover in the removed state from the housing. 
     FIG. 3 is a vertical cross-sectional view showing the cover in an attached state with the housing. 
     FIG. 4 is a horizontal cross-sectional view showing the cover in the attached state with the housing. 
     FIG. 5 is a cross-sectional view of FIG. 4 along the line X—X. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     An embodiment of the present invention is explained below with the aid of FIGS. 1 to  5 . 
     A connector of the present embodiment is provided with a housing  10  made from plastic, and a cover  20 . The housing  10  has a pair of left and right cavities  11 , terminal fittings (not shown) being inserted from the posterior into these cavities  11 . An electric wire  12  is joined to each terminal fitting passes through a rubber stopper  13 , which is fitted to an opening of each cavity  11 . The electric wire  12  extends to the exterior of the housing  10 . A posterior end face of the housing  10  guides the electric wires  12  and in an approximately square electric wire guiding face  14  (also referred to herein as an “exit face”). The cover  20  is attached to a posterior end portion of the housing  10  so as to cover the electric wire guiding face  14 . 
     The housing  10  is provided with a centre locking arm  15  and a left and right pair of locking protrusions  16  which serve to maintain the cover  20  in an attached state with the housing  10 . The centre locking arm  15  is formed on an upper face of an outer circumference of a posterior end portion of the housing  10 . This centre locking arm  15  has a cantilevered shape which protrudes in a posterior direction, and an upper face of a protruding end thereof has a locking protrusion  15 A which protrudes beyond an outer face of the housing  10 . Left and right side edges of the centre locking arm  15  do not join with other parts of the housing  10 . That is, a pair of slits  17  are formed between the left and right side edges of the centre locking arm  15  and the upper face of the outer circumference of the housing  10  so that the centre locking arm  15  remains separate. These slits  17  are provided in the upper face of the outer circumference of the housing to the posterior, and bending spaces  18  are formed below the centre locking arm  15 . The pair of locking protrusions  16  are formed at lower portions of left and right side faces of the outer circumference of the housing  10 . 
     The cover  20  is approximately square in shape and is attached to the posterior end portion of the housing  10  so as to cover the electric wire guiding face  14 . The cover  20  fits with the exterior of the housing  10 , and has a posterior wall  22  which protrudes towards the posterior. When the cover  20  is attached to the housing  10 , this posterior wall  22  is opposite the electric wire guiding face  14 . A central portion in a left-right direction of a lower face of the cover  20  has a cut-away  23  which is open at its anterior edge. Left and right edges and a posterior edge of the cut-away  23  extend downwards, and form a guiding member  24 . An anterior face and a lower face of the cover  20  are open. When the cover  20  is in an attached state with the housing  10 , the electric wires  12 , which are guided outwards via the electric wire guiding face  14 , are bent downwards within the cover  20  and are guided downwards to the exterior of the cover  20  from a lower face of the guiding member  24 . 
     The cover  20  is provided with a locking hole  25  and a left and right pair of side locking arms  26  as a means to maintain the cover  20  in an attached state with the housing  10 . The locking hole  25  passes from an inner side to an outer side. When the cover  20  is attached, the locking protrusion  15 A of the centre locking arm  15  engages with the locking hole  25 , thereby locking the cover  20 . When the cover  20  is to be removed, the locking protrusion  15 A, which is in the locking hole  25 , is pressed, thereby causing the centre locking arm  15  to bend, and the lock is thereby released. The pair of side locking arms  26  are provided on left and right side faces of the cover  20 , these side locking arms  26  consisting of a long and narrow portion of each side wall which extends in an anterior-posterior direction. A locking protrusion  26 A is formed at an anterior end of each locking arm  26 , these locking protrusions  26 A protruding inwards from the inner circumference of the cover  20 . A lower edge of each side locking arm  26  is unified with the lower half of the side walls of the cover  20  and approximately L-shaped circumference walls  27  which extend up to outer side edges of the lower face of the cover  20 . Further, both posterior ends of theses L-shaped circumference walls  27  are joined by the posterior wall  22  of the cover  20 . Lower edges of the circumference walls  27  join at approximately right angles with upper ends of the guiding member  24 . Recessed grooves  28  are formed between upper ends of the side locking arms  26  and upper halves of the side walls of the cover  20 , these recessed grooves  28  being open at the anterior end. As a result, the upper ends of the side locking arms  26  do not join with other parts of the cover  20 . 
     Next, the operation of the present embodiment will be explained. 
     The cover  20  may be attached by pressing it onto the housing  10  from the posterior. During this attachment process, the locking protrusion  15 A of the centre locking arm  15  makes contact with the anterior end of the upper face of the cover  20 , and is thereby bent downwards (towards the inner side). Simultaneously, the locking protrusions  26 A make contact with the locking protrusions  16  of the housing  10 , and are thereby bent outwards. When the cover  20  has reached a correct fitted state, the centre locking arm  15  returns to its original position and the locking protrusions  15 A thereof engages with the locking hole  25  of the cover  20 . Simultaneously, the side locking arms  26  return to their original position and the locking protrusions  26 A thereof engage with the locking protrusions  16  of the housing  10 . These operations latch the cover  20  to the housing  10 . 
     If, in this attached state, the electric wires  12  receive a pulling force from the side so as to press on the lower edge of the guiding member  24 , this pulling force is transmitted via the guiding member  24  and the circumference walls  27 , and acts as a force to bend the side locking arms  26  outwards (in a direction of separation from the locking protrusions  16 ). However, in the present embodiment, the lower edges of the side locking arms  26  are joined to the L-shaped circumference walls  27 , and both circumference walls  27  are joined to the posterior wall  22 . As a result, the rigidity thereof is increased and the side locking arms  26  are not bent in the lock separating direction. 
     Further, if the electric wires  12  receive a pulling force from the posterior (a direction of separation from the electric wire guiding face  14 ) so as to press on the lower end of the posterior wall  22 , this pulling force is transmitted via the posterior wall  22 . the guiding member  24  and the circumference walls  27 , and acts as a force to bend the side locking arms  26  towards the posterior of the locking protrusions  16 . However. in the present embodiment, the lower edges of the side locking arms  26  are joined to the L-shaped circumference wall  27 , and both circumference walls  27  are joined to the posterior wall  22 . As a result, the rigidity thereof is increased, and the side locking arms  26  are not released from their latched state. 
     The cover  20  is separated from the housing  10  by pressing the protrusion  15 A which is in the locking hole  25 , with a jig (not shown). The centre locking arm  15  is bent towards the interior, and the latch between the centre arm  15  and the hole  25  is released. Next, while this state is being maintained, the cover  20  is inclined to the left or the right (as seen from above), so as to pull either the left or right side wall towards the posterior. As a result, the left and right side walls widen, and one of the side locking arms  26  separates from its locking protrusion  16 . Next, the cover  20  is inclined in the opposite direction and the other side locking arm  26  separates from it locking protrusion  16 . By this means, all of the arms  15  and  26  are released. Next, the cover  20  may be separated from the housing  10  by pulling it towards the posterior. 
     Neither of the two side edges of the centre locking arm  15 , which is pressed by the jig when the separating operation is performed, join with other parts. Consequently the rigidity of the centre locking arm  15  is low and the lock is easily released by the jig. In the present embodiment, the centre locking arm  15  has a reduced rigidity and consequently the lock-release operation thereof is improved. Moreover, the side locking arms  26  have an increased rigidity, and consequently they are not released from their locked state as a result of interference from the electric wires  12 . 
     Furthermore, the centre locking arm  15  and the side locking arms  26  are formed on mutually opposing components (the centre locking arm  15  being formed on the housing  10 , and the side locking arms  26  being formed on the cover  20 ). As a result, changing the materials from which the housing  10  and the cover  20  are formed can reduce the rigidity of the centre locking arm  15  and increase the rigidity of the side locking arms  26 . By this means, the lock-release operation of the centre locking arm  15  is improved, and the side locking arms  26  are not released from their locked state as a result of interference from the electric wires  12 . 
     The materials from which the housing  10  and the cover  20  are formed can be specified so as to confirm to the strength required of the housing  10  and the cover  20 , to the protruding length, thickness, and width of the centre locking arm  15 , and to the rigidity required thereof, and to conform to the protruding length, thickness of the side locking arms  26 , to the thickness, dimensions in the circumference direction, and shape of the circumference walls, and to the rigidity required of the side locking arms  26 , etc. 
     The present invention is not limited to the embodiments described above with the aid of figures. For example, the possibilities described below also lie within the technical range of the present invention. In addition, the present invention may be embodied in various other ways without deviating from the scope thereof. 
     (1) In the present embodiment, the centre locking arm is formed on the housing and the side locking arms are formed on the cover. However, the centre locking arm could be formed on the cover and the side locking arms could be formed on the housing, or both the centre locking arm and the side locking arms could be formed on the housing, or all the locking arms could be formed on the cover. 
     (2) In the present embodiment, both the side locking arms are formed on the cover. However, one of the pair of side locking arms could be formed on the cover and the other side locking arm could be formed on the housing. 
     (3) In the present embodiment, the L-shaped circumference walls which join with the side locking arms are provided on the side opposite the centre locking arm. However, the L-shaped circumference walls could be provided on the same side as the centre locking arm.