Abstract:
The invention concerns an electrical connector, in particular for use between a receptacle (squib) and an electrical control for a restrain system in motor vehicles.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of The Invention 
     The invention concerns an electrical connector, in particular for use between a receptacle (squib) and an electrical control for a restraint system in motor vehicles. 
     2. Description of Related Art 
     Such a connector is known from EP 0 591 947 A2, EP 0 591 948 A2, DE 195 00 959 C2 and DE 195 13 358 C1. 
     A connector according to the generic type has a very limited size (for example 2 to 3 cm long, about 1 cm wide and 0.1 to 1.0 cm high). Thus, the individual components of the connector or the associated receptacle are extremely small. Nevertheless, easy mounting and high reliability are required for applications concerning safety regulations (for example belt tensioner, air bag). 
     This is particularly true with respect to the engagement of the connector and the receptacle, where it is required that the contact springs of one of the components reliably contact the contact pins of the other component in the assembled condition, while not allowing the connector and the receptacle to become detached accidentally. 
     This problem is resolve in the prior art in that the connector and the receptacle are contacted and brought into engagement with each other in a first step and a locking member is brought behind catching arms of the connector as a so-called secondary locking in a second step, in order to prevent accidental detachment. 
     In principle, this constructive solution has proved its worth, but it requires two steps in assembly. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to develop a connector of the type mentioned above in which mounting is made easier without disadvantages with respect to the reliability of contact and the safety of engagement. 
     In order to solve this problem, the invention starts from the following premise. Contrary to the prior art, the locking member is formed in such manner that it can be arranged in the housing before engagement of the connector and receptacle. The locking member is mounted in such a manner that the catching arms are “blocked” to prevent engagement of the connector and the receptacle in that position. 
     In order to facilitate the engagement of the connector and the receptacle, the invention further provides for the locking member to be fed temporarily deeper into the housing to such a position in which the catching arms may be moved for engagement with the receptacle. 
     For that purpose, a goal of the invention is to adapt the locking member and the housing in such a manner that the locking member is situated in an initial (mounted) position which is in a “raised” position against the action of a spring, and such that it may be pushed deeper into the housing against the action of the spring for engagement of the connector and receptacle, and, therefore, moves back (springs back) automatically, because of the spring action, to the initial position after the connector and the receptacle have come into engagement. 
     In this way it is assured that the catching arms of the housing are secured against accidental detachment from the catching means of the receptacle when the connector and the receptacle are engaged. 
     The invention comprises an electrical connector, in particular for use between a receptacle (squib) and an electrical control for a restraint system in motor vehicles, having the following features: 
     a housing for receiving electrical cables and having contact springs connected thereto, 
     the contact springs serving to receive contact pins of the associated receptacle, and 
     resilient catching arms on the housing for securing the housing to the receptacle, and 
     a locking member having a number of locking arms corresponding to the number of catching arms, 
     The invention in its most general embodiment is characterized in that 
     the housing has a spring acting on a base part of the locking member, which pushes the locking member from a maximum insertion position in which the catching arms are free to move into a locking position with corresponding catching means on the receptacle to a position in which the locking arms secure the catching arms against accidental detachment. 
     The fundamental advantage of the connector described above is that the locking member may be mounted in a factory and that this step can be eliminated in mounting, for example in a motor vehicle. 
     For mounting the mechanic proceeds as follows: 
     He takes the connector, puts it on the receptacle and pushes a base part of the locking member, for example. The locking arms are pushed deeper into the housing thereby, that is to a position in which they do not hinder a backward movement of the catching arms of the housing. 
     In that condition the connector is pushed into the receptacle until the contact pins of the receptacle are placed in the contact springs of the connector and the catching arms are engaged behind the corresponding catching means of the receptacle. 
     Then the mechanic relieves the pressure on the base part of the locking member (by taking off his hand from the connector), which springs back automatically because of the spring described above and moves the locking arms to a position in which they are positioned behind the catching arms of the housing to lock them in the sense of a secondary locking. Now, the receptacle and the connector are connected functionally and are secured against detaching. 
     All the steps mentioned above can be carried out with one hand and in one operation. 
     For detaching the connector and the receptacle the mechanic pushes against the base part, for example, and thereby pushes the locking arms against the action of the spring to the maximum insertion position so that the catching arms are “free” and the connector may be detached from the receptacle. 
     The constructive design described above may be realized both in a bent embodiment, as described in DE 195 00 959 C2, and in an “axial” embodiment, as disclosed by DE 195 13 350 C1, in which the locking member is displaceable in the direction of insertion. 
     In order to enable a locking function with respect to the catching arms (in the locking position) on the one hand and movement of the catching arms during the process of insertion (insertion position) on the other hand, an embodiment of the invention provides locking arms with a rod-like portion and a widened region at the free end and catching arms having a recess on their surfaces facing the locking arms, respectively, which enables the reception of the associated rod-like portion in the maximum insertion position of the locking member. An alternative embodiment provides the end of the locking arms towards the respective catching arm with an enlargement (thicker). 
     Here the locking arms may be “T-shaped” —as illustrated in the embodiments. 
     In the locking position (“raised” position of the locking member) the widened (or enlarged) portion of the locking arms is situated behind the catching arms and prevents movement thereof. On the other hand, in the insertion position each widened or enlarged portion of each locking arm projects downwards beyond the associated catching arm. The catching arms spring “towards the inside” in connecting them to the associated receptacle, because the catching arms have longitudinally grooves on the back, which reach beyond the tapered rod-like portions of the locking arms or because the catching arms and the locking arms are spaced apart. 
     Another embodiment of the connector arranges the locking arms of the locking member in parallel and spaced apart, with at least one transversal web extending beside the locking arms, which has at least one catching projection or a recess on its outer face, which catches at least one recess or at least one catching projection (detent) of the housing in the locking position of the locking member. 
     An accidental detachment of the locking member is prevented reliably in this manner. 
     In analogy to the embodiment according to DE 195 00 959 C2 the connector may have a three-part housing having a housing bottom for receiving the contact springs, a housing top for covering the housing bottom and securing the electrical cables between the housing bottom and top, as well as said locking member which can be inserted into the housing top through a corresponding opening, arranged in the housing top. 
     The housing top and/or the locking member may be connected to the housing (bottom) via resilient tongues. 
     The linkage of the locking member via resilient tongues supports the movement of the locking member from the maximum insertion position to the (raised) locking position. 
     Guiding and mounting the locking member is facilitated, if the housing has a collar around its portion for receiving a base part of the locking member, projecting beyond the base part in the inserted condition of the locking member. 
     The design of the spring on the housing may be chosen so that the spring is unstressed when the locking member is not inserted as well as when in the locking condition. Thereby, the spring is actuated only when the locking member is pushed into the insertion position. That single stress on the spring increases the reliability of the spring which typically will only be stressed a second time after years, when the connector is to be detached from the receptacle. 
     Further advantages of the connectors are: 
     The catching arms are locked in the condition of delivery of the connector. In that way an accidental placement of the connector on a receptacle is prevented. 
     When the connector is brought into engagement with the receptacle, a complete engagement is always assured. Because of the action of the spring in situ the locking member is brought automatically to the position of the secondary locking after the mounting process. In this respect it is impossible for the mechanic to forget to bring the locking member in its functional position. 
     Mounting is simplified and shortened, because the insertion and locking are effected in a single operation. 
     Further characteristics of the invention follow from the detailed disclosure which follows. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES OF DRAWING 
     The invention is explained in more detail below with an embodiment shown in the following figures of drawing wherein: 
     FIG. 1 is a perspective view of a connector with a locking member, not inserted. 
     FIG. 2A is a perspective view of the connector according to FIG. 1 in the condition of delivery. 
     FIG. 2B is a sectional view of the connector depicted in FIG.  2 A. 
     FIG. 3A is a perspective view of the connector in a position in which it is brought into engagement with an associated receptacle. 
     FIG. 3B is a sectional view of the connector depicted in FIG.  3 A. 
     FIG. 4 is a schematic view of spring  40  taken on a plane of symmetry of the connector of the invention. 
    
    
     Sectional views are related to each of the FIGS. 2 and 3, which show the respective position of the catching arms on the housings with respect to the corresponding arms of the locking member. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A connector being indicated as a whole with reference number  10  in FIG. 1 consists substantially of a housing  12  and a locking member  16  connected thereto via tongues  14 . 
     The housing  12  has a snout-like projection  18  in a downward direction, in which contact springs are situated for receiving contact pins of an associated receptacle. 
     Catching arms  22  extend adjacent to lateral surfaces  20  of the snout  18 , which project downwards from the upper housing body and have arched detents  24  on the outside. 
     A recess  26  can be seen on the top of the housing  12 , which is limited on three sides by a collar  28  of the housing. 
     Four slot-like openings are disposed in the bottom  26   b  of the recess  26 , which serve to receive the corresponding parts of the locking member  16 . 
     The locking member  16  comprises two lateral locking arms  30  projecting perpendicularly from a base part  32 . 
     Each locking arm  30  comprises a rod-like portion  30   s  and a widened region  30   v  at the end so that a shape more or less like a T results for each locking arm  30  in the view according to FIG.  1 . 
     Two further arms  34  extend adjacent to the outer edge  32   r  of the base part  32 , beside the locking arms  30 , each of which has a detent  34   r  on its outside. 
     The connector according to FIG. 1 is fabricated in the factory in a manner as shown in FIG.  2 . In this manner, locking arms  30  and the arms  34  of the locking member  16 , respectively, are inserted into the corresponding slots in the region of the recess  26 , the end position (mounting position) being reached when the detents  34   r  of the arms  34  catch corresponding openings of the housing. 
     In that position the base part  32  of the locking member  16  is situated on a spring  40  formed in the region of the recess  26 , in such a manner that the spring  40  is unstressed. 
     As is shown in FIG. 1, spring  40  extends freely from a region  40   a  of connection on the housing into recess  26 . Under spring  40 , bottom  26   b  of recess  26  is formed having an opening  26   o.    
     In the mounting position widened region  30   v  at the ends of the locking arms  30  are situated immediately behind the catching arms  22  of the housing and prevent catching arms  22  from being moved in the direction of arrow R. 
     For connecting the connector to an associated receptacle (not illustrated), a mechanic takes connector  10  and pushes the top of base part  32  which is moved thereby in the direction of arrow D (FIG. 3) against the force of spring  40 . At the same time locking arms  30  are inserted deeper into housing  12 , to a position as shown in the sectional view of FIG.  3 B. In that maximum insertion position of locking member  16  widened portions  30   v  of locking arms  30  are situated under detents  24  and catching arms  22 . Accordingly, when placed upon the receptacle catching arms  22  spring behind corresponding catching means of the receptacle because catching arms  22  have corresponding recesses on the back (adjacent to the locking arms  30 ), which reach beyond the rod-like portions  30   s  of the locking arms  30 , respectively. 
     When the receptacle is being inserted on the connector catching arms  22  move in the direction of arrow R to engage corresponding catching means of the receptacle. Once engaged they move back under spring action to their unstressed position (catching position). 
     If the mechanic relieves the pressure on base part  32  after the catching arms  22  have engaged the catching means on the receptacle spring  40  acts on base part  32  and pushes locking member  16  upwards by a distance so that the widened portions  30   v  of the locking arms are again situated behind the catching arms  22 , as shown in the sectional view of FIG.  2 B. 
     The locking condition in which the spring  40  is again unstressed corresponds to the condition according to FIGS. 2A and 2B.