Locking mechanism for molded resin component

1. A resin molded parts locking mechanism, comprising:

a lock projection provided on a first part and a lock arm provided on a second part to be combined with the first part, whereby, by moving the second part in a specific straight line direction with respect to the first part, the lock arm is engaged with the lock projection, wherein

the lock arm is formed as a cantilever-like elastic arm which has a fixed rear end in the moving direction of the second part with respect to the first part and a free front end in the moving direction, can be deflected in a direction orthogonal to the moving direction, and also has, at a position on the free end side on one side surface in the deflecting direction, an engagement projection engageable with the lock projection;

the first part has a first wall surface extending along the moving direction of the lock arm to cross orthogonally the deflecting direction of the lock arm, being opposed to one side surface in the deflecting direction of the lock arm, and having the lock projection;

the lock projection has, in its front surface opposed to the moving direction of the lock arm, an inclined surface which, when the engagement projection of the lock arm climbs it with the movement of the second part, deflects the lock arm gradually in a direction to part away from the first wall surface, and, in its back surface opposed to the front surface, a lock wall which, when the engagement projection overruns the top of the lock projection and the lock arm returns from its deflected state to its initial position, is opposed to and engaged with the lock wall of the engagement projection of the lock arm, thereby preventing the second part from moving oppositely to the moving direction;

the first part has a second wall surface opposed to the first wall surface across the lock arm;

the lock arm also has, between the engagement projection on the other side surface in the deflecting direction and the fixed end, a pressing projection which, when the engagement projection of the lock arm climbs the inclined surface of the lock projection and the lock arm is thereby deflected in a direction to part from the first wall surface, presses the second wall to give the lock arm a pressing force opposite to the deflection direction, thereby enhancing the substantial flexural rigidity of the lock arm; and

the second wall has an opening which, when, with movement of the second part, the engagement projection of the lock arm starts to climb the inclined surface of the lock projection to thereby start to deflect the lock arm in a direction to approach the second wall surface, stores the pressing projection therein and, when, with further movement of the second part, the engagement projection of the lock arm has climbed the inclined surface of the lock projection and is going to reach the top of the lock projection, allows the pressing projection to be slide contacted with an edge of the opening while pressing the edge, thereby giving the lock arm a pressing force opposite to the deflecting direction.

2. The resin molded parts locking mechanism according to claim 1 , wherein

the first part is a connector housing, and the second part is a spacer for locking a terminal inserted into the terminal housing chamber of the connector housing;

the spacer can be inserted orthogonally to the insertion direction of the terminal into the terminal housing chamber;

the connector housing secures the housing space for the spacer;

the housing space has, in a portion thereof, an insertion space having the first wall surface and second wall surface as opposed walls for inserting the lock arm;

the first wall surface is formed inside the insertion space, whereas the second wall surface is formed outside the insertion space; and

the first wall surface includes, as the above lock projection, a lock projection for locking the spacer in a position for restricting the insertion-direction movement of the terminal, and, in front of the lock projection in the insertion direction of the lock arm, a temporary lock projection, when engaged with the engagement projection of the lock arm, for locking the spacer temporarily in a position allowing the insertion-direction movement of the terminal.

3. The resin molded parts locking mechanism according to claim 2 , wherein

the opening is formed at a position capable of visually confirming, through the opening, the pressing projection of the lock arm temporarily locked.