1. Field of the Invention
The present invention relates to a connector lock mechanism. More particularly, the present invention relates to a connector lock mechanism in which a half-fitted condition is positively prevented by a disengaging force (repelling force) produced between a pair of connector housings to be fittingly connected together so that the fitting connection to the mating connector can be positively locked.
The present application is based on Japanese Patent Application No. Hei. 11-243596, which is incorporated herein by reference.
2. Description of the Related Art
Usually, various electronic equipments are mounted on a vehicle such as an automobile, and therefore, naturally, various types of male and female connectors are provided at connection ends of various wires forming wire harnesses or the like.
Generally, male and female connectors to be fittingly connected together are provided with a lock mechanism, in which when the amount of fitting of the two connectors relative to each reaches a predetermined value, their respective connector housings are locked together in a fittingly-connected condition.
When the connector housings of the male and female connectors are connected together by the lock mechanism, each of connection terminals in the male connector housing is electrically connected to a respective one of connection terminals in the female connector housing with adequate contact pressure and contact area.
However, for example, when the operating force for fitting the two connector housings together is inadequate, and when either of the connector housings or any of the connection terminals is defective, the connector fitting operation is sometimes finished in a half-fitted condition in which the amount of fitting of the two connector housings relative to each other fails to reach the predetermined value.
When the male and female connectors are used in such a half-fitted condition, they may be disengaged from each other because of vibrations, developing during use, and the tension of a wire harness, and this can leads to a disadvantage that the feeding of electric power is interrupted. Even if the two connectors are not disengaged from each other, there is a possibility that in the half-fitted condition, the mating connection terminals are incompletely electrically connected together, in which case the necessary electrical characteristics are not obtained, and this may lead to a disadvantage that the associated electric part is subjected to a malfunction.
Therefore, in order to prevent an accident due to a failure to notice such a half-fitted condition of the two connectors, there has been proposed a lock mechanism (which locks two connector housings in a mutually-connected condition) having a half-fitting prevention function for disengaging the two connector housings from each other when a half-fitted condition is encountered.
FIG. 8 shows a related connector lock mechanism having a half-fitting prevention function.
In this connector lock mechanism, a lock arm 5 is formed on an outer surface of a male connector housing 2 (one of male and female connector housings 2 and 3 to be fitted together in a male-female manner), and extends in a connector housing-fitting direction, whereas arm engagement portions 7 are formed on the female connector housing (the other connector housing) 3, and these arm engagement portions 7 retain engagement projections 5b of the lock arm 5, respectively, to lock the two connector housings together in a connected condition when the amount of fitting of the two connector housings relative to each other reaches a predetermined amount.
Female connection terminals are received respectively in terminal receiving chambers 2a formed in the male connector housing 2, and male connection terminals 9 are received respectively in terminal receiving chambers formed in the female connector housing 3.
The lock arm 5 has a pair of elastic arms 5a extending from a proximal end portion of the housing toward a distal end thereof, and the engagement projection 5b is formed on and projects laterally from an outer side surface of each of the elastic arms 5a at a distal end thereof.
The arm engagement portions 7 are formed in a projected manner respectively on inner surfaces of opposite side walls 3b and 3b of a front housing portion 3a, defining a space into which the male connector housing 2 can be fitted. Each of the arm engagement portions 7 has a slanting surface 7a and a retaining surface 7b. When the amount of fitting of the two connector housings relative to each other is less than the predetermined value, each slanting surface 7a presses the corresponding engagement projection 5b toward a vertical median plane of the housing to elastically deform the elastic arm 5a toward the vertical median plane of the housing, thereby producing a disengaging force urging the two connectors away from each other. When the amount of fitting of the two connector housings reaches the predetermined value, so that the elastic deformation of each elastic arm 5a by the corresponding slanting surface 7a is canceled, each retaining surface 7b retains the corresponding engagement projection 5b. 
Namely, in the above connector lock mechanism, when the male and female connector housings 2 and 3 are fitted together, the elastic arms 5a are elastically deformed respectively by the slanting surfaces 7a through the engagement projections 5b, and as a result the disengaging force, tending to move the two connector housings 2 and 3 away from each other, is produced between each slanting surface 7a and the corresponding engagement projection 5b by the resilient force of the thus elastically-deformed elastic arm 5a. In this construction, any spring member (e.g. a compression coil spring), separate from the connector housings, is not used for producing the disengaging force to disengage the two connectors from each other, and therefore the half-fitting prevention function is achieved at a low cost without increasing the number of the component parts.
In the above lock mechanism, however, the arm engagement portions 7 are formed on the inner surface of the connector housing 3, and therefore the condition of engagement of the lock arm 5 with the arm engagement portions 7 can not be confirmed with the eyes, and thus there has been a disadvantage that the fitting connection can not be confirmed with the eyes.
And besides, for canceling the locked condition, the proximal end portion of the lock arm 5 is pressed so as to turn its distal end portion downwardly, and therefore a large operating force is required when canceling the locked condition, and this has invited a problem that the cancellation of the locked condition is difficult.
It is therefore an object of the present invention to overcome the above problems, and more specifically to provide a connector lock mechanism in which a half-fitted condition is positively prevented, and a condition of engagement of a lock arm with an arm engagement portion can be confirmed with the eyes, and besides an operating force, required for canceling a locked condition of the two connector housings, can be reduced.
To achieve the above object, according to the present invention, there is provided a connector lock mechanism which comprises an elastically-deformable lock arm formed on an outer surface of one of male and female connector housings which are fittable to each other, the lock arm extending in a connector fitting direction, at least one engagement projection formed on the lock arm, at least one arm engagement portion formed on an outer surface of the other one of male and female connector housings, wherein when the male and female connector housings are completely fitted to each other, the arm engagement portion retains the engagement projection of the lock arm to lock the male and female connector housings, at least one push-out guide surface formed on the arm engagement portion, wherein when the male and female connector housings are in a half-fitted condition, the push-out guide surface deforms the lock arm elastically in a direction away from the outer surface of the one of male and female connector housings, thereby producing a disengaging force urging the male and female connector housings away from each other, and at least one retaining portion formed on the arm engagement portion, wherein when the male and female connector housings are completely fitted to each other so that elastic deformation of the lock arm by the push-out guide surface is canceled, the retaining portion retains the engagement projection, wherein engagement of the engagement projection with the retaining portion is canceled by elastic deformation of the lock arm in a direction substantially parallel to the outer surface of the other one of male and female connector housing.
In the above construction, the lock arm and the arm engagement portion are formed on the outer surfaces of the connector housings, respectively, and those portions of the lock arm and the arm engagement portion, engaged with each other, are exposed to the outsides of the two connector housings.
Therefore, the condition of engagement of the lock arm with the arm engagement portion can be easily confirmed with the eyes. When canceling the locked condition of the two connector housings, the lock arm can be elastically deformed by operating or manipulating the pivotally-movable distal end portion of this lock arm, and therefore the operating force, required for canceling the locked condition, can be reduced.
The lock arm is elastically deformed in the direction away from the outer surface of the connector housing so as to produce the disengaging force during the connector fitting operation. On the other hand, when canceling the locked condition of the two connector housings, the lock arm is elastically deformed in the direction generally parallel to the outer surface of the connector housing.
Therefore, a clearance between the outer surface of the connector housing and the lock arm can be minimized, and therefore the vertical dimension of the pair of connectors can be reduced.
For example, the cross-sectional shape or other of the lock arm is determined such that the lock arm has a high elastic coefficient (elasticity modulus) in the direction away from the outer surface of the connector housing, but has a low elastic coefficient in the direction generally parallel to the outer surface of the connector housing. With this arrangement, the disengaging force for preventing a half-fitted condition can be set to a sufficiently-large value while the operating force for canceling the locked condition can be kept to a small level.
In the above connector lock mechanism, it is preferable that the engagement projection is formed on a lateral side surface of the lock arm. In the above connector lock mechanism, it is preferable that the push-out guide surface has a smoothly slanting portion.