Patent Publication Number: US-6341972-B1

Title: Connector with secondary latching and with a lateral cable outlet

Description:
The invention relates to a connector with secondary latching. 
     Connectors of this kind are used e.g. in the motor industry in order to produce electric connections which meet exacting requirements. The requirements relate on the one hand to the reliability with which such a connection must be made and on the other hand to protection against inexpert handling of the connector. The secondary latching is designed to ensure that when the latch closure has engaged, its position is subsequently secured so that the connection cannot be accidentally broken, e.g. by pulling the connection cable in question. On the other hand the secondary latching can be designed so that it also engages and can subsequently be released by hand or only with a special tool. This prevents unauthorised opening. These requirements apply particularly to passenger-retaining systems in motor vehicles, where the connector connects the trigger of an airbag propelling charge, e.g. in the impact cup of a steering wheel, to the vehicle power circuit. During assembly of conventional connectors of this kind, problems occur regarding clear recognition of the state in which the connector is in during assembly. In other words sometimes the person installing the airbag is not sure whether actuation of the secondary-device handle will engage it in the locked position or whether it has already engaged and therefore cannot be correctly inserted. If this happens at an unduly early stage during installation, during subsequent assembly and particularly when the electric power system starts up, the ignition charge may be subjected to voltages which trigger the airbag system. This may result in dangerous injury to the fitters, or the circuit may not be closed in which case the airbag will not operate. 
     In addition, even when relatively strong forces act on the handle of the secondary latching, engagement in the locked position should be possible only if expressly desired. The purpose is e.g. to avoid faulty operation during transport and handling. 
     The present invention further relates to a connector with a lateral cable outlet of the kind described in the preamble of claim  17 . Connectors of the aforementioned kind, with a lateral cable outlet and a casing which is flat in the direction of insertion, are used whenever it is necessary, for reasons of space, to bend the connecting cable by about 90° from the axis of the connector, immediately behind the plug attachment. A situation of this kind occurs e.g. with ignition plugs for airbag-retaining systems, where the airbag and the ignition mechanism are disposed on the impact cup of the steering wheel, where the overall height is restricted. 
     In the case of connectors with a lateral cable outlet and a flat casing, there is always a risk that their cable will be pulled out of the mating connector. Although this method of disengaging the connector is not according to specifications, precautions must be taken to reduce the damage in this case to a minimum. This means that the plug casing must not be torn apart and possibly irreversibly deformed by the resulting lever forces. It is also necessary to prevent the cable ends from being partly or completely disconnected from the backs of the plug. 
     The object of the invention therefore is to propose a connector with secondary latching and having a state on assembly which is clearly defined at all times and has maximum reliability for avoiding unintentional premature latching. 
     The further object of the invention is to improve a connector according to the invention with a lateral cable outlet so that when an axial or oblique pull is exerted on the cable end, it is effectively protected from disconnection and damage to the casing. 
     These problems are solved according to the claims. Advantageous embodiments of the invention are specified in the sub-claims. 
     In order to show the fitter the exact position in which the connector according to the invention is, there are two engaged positions—a first position in which the secondary latching is not yet operative, so that the plug can still be pulled out, and a second position in which the connector is latched and a special tool may be needed to release the handle. 
     According to another feature of the invention, a locking slide is provided in the lid of the casing of the connector, so as to prevent the secondary latching being pressed down out of the assembly position into the latched position unless the locking slide is deliberately pushed sideways. This reliably prevents accidental final latching during assembly. 
     Alternatively the handle is disposed so as to be movable transversely to the direction of insertion, so that in the assembly position the handle cannot be pressed into the latched position, this being possible only after being deliberately moved sideways into a position in which the handle can be pressed into the latched position. 
     These features ensure that faulty operation during assembly is substantially prevented, and during assembly the fitter will always know the exact state of the connector when installed, so that it cannot be latched prematurely. 
    
    
     The invention will now be explained in detail by a description of preferred embodiments with reference to the drawings in which: 
     FIG. 1 shows an embodiment of a connector according to the invention in section and in the assembly and in the latched position; 
     FIG. 2 shows a variant of the embodiment in FIG. 1, in the assembly position; 
     FIG. 3 is a view in cross-section of a connector according to the invention with a locking slide for preventing premature latching; 
     FIG. 4 shows the latching-preventing means in FIG. 3 in plan view; 
     FIG. 5 shows an alternative latching-preventing means in perspective view; 
     FIG. 6 a-c  shows the latching-preventing means in FIG. 5 in three latch positions; 
     FIG. 7 is a perspective view of the connector according to the invention and 
     FIG. 8 is an exploded view of the connector in FIG.  7 . 
    
    
     FIG. 1 is a longitudinal section through a connector  1  comprising a plug part  10  and a socket part  7 . The socket part  7 , in the case of an airbag-retaining system, is a part of the casing of the ignition mechanism. On each side of the plug axis  6 , the plug part  10  has tongues  4   a,    4   b  which engage in corresponding slots  3   a,    3   b  in the socket part  7 , where latches  5   a,    5   b  engage in undercuts the shoulders  8   a  and  8   b  of in the slots  3   a,    3   b.  In the case shown here, the latches have sloping flanks on each side, so that after engagement, the plug part  10  can be pulled out by pulling it strongly. The slots  3   a,    3   b  have a width such that after the latches  5   a,    5   b  have engaged behind the tongues  4   a,    4   b  an additional slot  9   a,    9   b  for receiving the locking arms  2   a,    2   b  of the handle  2  is formed in the direction of the plug axis  6 . 
     FIG. 1 shows the handle  2  in the assembly position A on the right half and in the latched position B on the left half. In the assembly position, the locking arms  2   a,    2   b  are not received in the slots  9   a,    9   b.  On each side the lateral wings  11   a,    11   b  surround the plug part  10  and the latch hooks  12   a,    12   b  engage in corresponding grooves formed in the side walls of the plug part  10 , so as to lock the handle  2  in this assembly position. In this position, therefore, the plug part  10  can be fitted on the socket part  7 , and can also be released from this position by strong pulling, since the latches  5   a,    5   b  can pivot out of the corresponding undercuts. This situation is shown in FIG. 2, which clearly shows that the tongues  4   a,    4   b  pivot in the free slots  9   a,    9   b.    
     In order finally to latch the connector  1 , the handle  2  is pressed in the direction for insertion, so that the sloping end faces of the latch hooks are pressed out of the slots  13   a,    13   b,  slide along the side walls of the plug part  10 , and finally are latched to the lower edge of the side walls of the plug part  10 . In this position the locking arms  2   a,    2   b  have entered the slots  9   a,    9   b  and prevent the latches  5   a,    5   b  from swinging back, thus ensuring that the connector has actually been latched. The handle  2  can be latched to the lower edges of the side walls of the plug part  10  in such a manner that a special tool is necessary for releasing it. 
     FIG. 3 shows the plug part  10  in longitudinal section. The cable outlet is shown on the right side and a chamber e.g. for a choke is provided on the left side. The handle  2  is on the plug axis  6  and is shown in FIG. 3 in the assembly position, i.e. the locking arms  2   a,    2   b  are not completely inserted into the slots  9   a,    9   b.  The locking slide  30  prevents the handle  2  from being pressed into the latched position. The slide is mounted in a groove  31  in the casing lid  32  so as to be movable transversely to the direction  6  of engagement and can be moved between a locking position and a position in which it enables the handle  2  to be inserted. In the locking position, the locking slide  30  is engaged by suitable latches  29  on the lid and on the slide. On its surface, the locking slide  30  has grooves  34  which facilitate sliding thereof and enable the locking slide to terminate flush with the lid surface, so that the resulting connector has a very flat construction, particularly since the transverse strut  20  of the handle  2  is also lowered into the groove  31  in the latching position. 
     A pin  33  is disposed on the underside of the transverse strut  20  and in the assembly position adjoins the locking slide. Its length is chosen so that in this position the tips of the locking arms  2   a,    2   b  just extend into the slots  9   a,    9   b.    
     FIG. 4 is a plan view of the locking slide  30  on the casing lid. The drawing shows an alternative means of securing the locking slide  30 , two recesses  39  being provided at the side in the groove  31 , for a latch  36  disposed in the side wall of the locking slide  30 . In the final latched position, the handle  2  along with the locking slide  30  can be pressed down so far that its surface is flush with the casing lid surface. 
     FIG. 5 shows an alternative embodiment preventing accidental latching of the handle in the final position. In this embodiment the complete handle  2  is moved sideways in a groove  13   b  transversely to the direction of insertion  6 , into a position in which the locking arms  2   a,    2   b  can enter the slots  9   a,    9   b.  FIG. 5 shows the lateral groove  13   b,  in which the wings  11   a,    11   b  of the handle  2  are guided. Ribs  23  bound the lateral travel distance and prevent any accidental pressure on the handle  2  from spreading out the wings  11   a,    11   b  in a position in which the locking arms  2   a,    2   b  cannot enter the slots  9   a,    9   b.  In addition the connector is constructed so that in the initial latch position the locking arms  2   a,    2   b  additionally or alternatively extend upwards from the base of the casing and accidental actuation is impossible. The casing and the inside of the wings  11   a,    11   b  are formed with knobs and recesses  25 ,  26 , so that it is possible to detect when the handle is latched in the intermediate position. Latching of this kind is optional and can be omitted if required. 
     FIGS. 6 a  to  6   c  show a perspective view of the connector according to FIG. 5 in the initial latching position (FIG. 6 a ) in which the handle  2  cannot be pressed down. In order to reach the final position, the handle  2  must first be moved sideways into the position shown in FIG. 6 b,  so that it can then be pressed down into the end position (FIG. 6 c). As can be seen, in this version also the handle  2  is flush with the surface of the connector casing lid, so that the connector is flat.    
     FIG. 7 shows a plug part ( 1 ) as a whole comprising an attachment  10  inserted into a complementary plug (not shown) and also comprising a flat casing. The lateral cable outlet is shown on the right side. A cable  46 , indicated by chain lines, comes out of the cable outlet  40 . The upper part of the connector is covered by a lid  44 . A locking handle  45  extends through the lid down to latching arms which extend parallel to the plug attachment, in order to secure the connector after installation. 
     The cable outlet  40  has a two-part clamping device  50   a,    50   b  which will be explained in detail hereinafter. A part of the clamping device  50   a  comprises a hollow semicylindrical groove formed with retaining ribs  47 . A cable  46  is inserted in the groove and, when the casing components are fitted together in the specified manner, the retaining ribs are partly pressed into the cable sheath transversely to the cable axis. The upper part  50   a  of the clamping device is in the form of a side attachment  48  moulded in one piece on the lid  44  and has an upper wall  60 , the underside of which is formed with the upper groove  50   a  in its centre. The attachment  48  also has two vertical side walls  51   a  and  51   b.  Latches are formed on the insides of the side walls  51   a  and  51   b  and cooperate with corresponding complementary detents  53 . The detents  53  are on the second part of the clamping device  50   b,  which is likewise in the form of an attachment or clamp  49  integral with the casing. The clamp  49  likewise has a central semicylindrical groove with retaining ribs  47  forming the counterpart to the groove  50   a,  the cable  46  being clamped between them. On the two sides of the groove  50   b  the clamp has two arms  56 , substantially following the contour of the inner side walls, and their lower outer ends are flush with the lower edges of the vertical side walls  51   a,    51   b  of attachment  48 . The detents  53  and the corresponding latches  52  are disposed closely above the lower end of the side walls  51   a,    51   b  or the arms  56 . Preferably, the arms  56  are prestressed slightly outwards when cast, so that when the attachment  48  is locked to the clamp  49 , the detents  53  are pressed into the latches  52 . 
     If a force is exerted on the lid  54  by an obliquely upward or backward pull in opposition to the direction of insertion, tending to loosen the lid from the casing, application of a force in this direction will press the detent  53  more deeply into the corresponding latch  52  and, if the side walls  51   a,    51   b  yield outwardly, the arms  56  will follow the yielding movement, with the result that the detents  53  cannot be removed from the latches; on the contrary, the two parts of the clamping device are joined together even more firmly. The greater the pull from the direction of the lid and the further the side walls or arms of the clamp move apart, the more firmly the locking device spreads into the undercut of the lid. 
     This ensures that the parts of the casing cannot come loose and the cable cannot be pulled out in the axial direction, since the parts of the clamping device  50   a,    50   b  always remain firmly pressed together. 
     The preceding description of embodiments of the invention should not be regarded as limitative but only by way of illustration.