Electrical connector position assurance system

An electrical connector assembly includes a first connector having a first mating portion and a second connector having a second mating portion mateable with the first mating portion of the first connector. The second connector includes a projection which is at a first location when the connectors are fully mated and which is at a second location when the connectors are less than fully mated. A connector position assurance device is movably mounted on the first connector for movement between a first position and a second position. The projection blocks movement of the device to its second position when the projection is in its second location. The device includes a final latch for holding the connectors in mated condition when the device is in its second position.

FIELD OF THE INVENTION 
This invention generally relates to the art of electrical connectors and, 
particularly, to a system for assuring the position of a pair of mating 
connectors, particularly assuring that the connectors are fully mated. 
BACKGROUND OF THE INVENTION 
There are a variety of applications wherein it is desirable to assure that 
a pair of electrical connecting devices are properly mated or securely 
latched. In other words, it is desirable to detect whether the connectors 
are properly or improperly fitted together. This assurance is desirable 
not only in the initial interconnection of the connectors, but in 
applications where the connectors are exposed to vibrations and may become 
disconnected. 
For instance, one approach to assuring that connectors remain connected is 
to design the connectors with a high mating force which, in turn, results 
in a high unmating force. This approach is highly undesirable in 
applications wherein the connectors must be disconnected for inspection or 
servicing. On the other hand, reducing the mating forces of the connector 
assembly, in turn, reduces the unmating forces which is undesirable in 
many applications. In fact, the risk of unmated connectors can be 
life-threatening in some applications, such as in the electrical 
interconnections of a safety airbag of a motor vehicle. 
The present invention is directed to solving these problems by providing a 
simple and very effective system for assuring proper positioning or mating 
of a pair of electrical connectors. 
SUMMARY OF THE INVENTION 
An object, therefore, of the invention is to provide a new and improved 
connector position assurance system for assuring or detecting that a pair 
of connectors are properly mated or securely latched. 
In the exemplary embodiment of the invention, an electrical connector 
assembly is disclosed with a plug connector having a housing and a mating 
plug portion. A socket connector is provided for receiving the mating plug 
portion of the plug connector. 
The invention contemplates a connector position assurance system wherein a 
connector position assurance device is movably mounted on the plug 
connector for movement between a first position allowing mating of the 
connectors and a second position latching the connectors in fully mated 
condition. A projection on the socket connector is located in a recess in 
the plug connector when the connectors are fully mated. The projection is 
located outside the recess when the connectors are less than fully mated. 
The projection blocks movement of the connector position assurance device 
when the projection is located outside the recess. 
Generally, complementary interengaging preliminary latch means are provided 
between the connector position assurance device and the plug connector to 
hold the device in its first position. Complementary interengaging final 
latch means are provided between the connector position assurance device 
and the plug connector to hold the device in its second position. 
As disclosed herein, the socket connector has a generally cylindrical 
portion, and a pair of the aforesaid projections are provided in the form 
of ears projecting radially outwardly on diametrically opposite sides of 
the cylindrical portion. The connector position assurance device embraces 
a substantial portion of the plug connector and is slidable thereon 
between its first and second positions. The device includes a slot for 
accommodating the generally cylindrical portion of the socket connector. 
The slot is formed on two sides by flanges of the device, and the ears are 
located in the path of the flanges to block movement of the device when 
the ears are not in their respective recesses of the plug connector. 
Other objects, features and advantages of the invention will be apparent 
from the following detailed description taken in connection with the 
accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings in greater detail, and first to FIG. 1, the 
connector position assurance system of the invention, generally designated 
12, is incorporated in an electrical connector assembly, generally 
designated 14. The connector assembly includes a first or plug connector, 
generally designated 16, and a second or socket connector, generally 
designated 18. The connector position assurance system includes a 
connector position assurance device, generally designated 20, slidably or 
movably mounted on plug connector 16, as fully described hereinafter. 
More particularly, first or plug connector 16 includes a housing, generally 
designated 22, having a top wall 24 and a pair of opposite side walls 26 
which house appropriate electrical terminals (not shown) terminated to the 
conductors 28 of an electrical cable 30. The plug connector has a mating 
plug portion 32 projecting from the bottom thereof. A guide boss 34 having 
a ramped guide surface 34a projects laterally outwardly from each side 
wall 26. A preliminary latch boss 36, having a ramped surface 36a, 
projects upwardly from top wall 24 of housing 22. A final latch boss 38, 
having ramped surfaces 38a and 38b, also projects upwardly from top wall 
24. Lastly, a recess 40 is formed on the underside of plug connector 
housing 22 whereby the recess opens downwardly of the connector. The 
purposes and/or functions of guide boss 34, preliminary latch boss 36, 
final latch boss 38 and recesses 40 will be described hereinafter. 
Second or socket connector 18 includes a cylindrical portion 42 having a 
pair of projections 44 on diametrically opposite sides of the cylindrical 
portion at the top thereof. It can be seen that the projections are in the 
form of flat ears projecting outwardly from opposite sides of the socket 
connector. The projections are sized for fitting into recesses 40 in the 
underside of plug connector housing 22 as the two connectors are mated. 
The thicknesses of the projections are substantially equal to the depths 
of recesses 40 so that the bottom surfaces 44a of the projections are 
generally flush with a bottom surface 46 of plug connector housing 22 when 
the two connectors are fully mated. Socket connector 18 houses appropriate 
terminal means, not shown, for mating with appropriate terminal means of 
plug connector 16. 
Connector position assurance device 20 is sort of box-shaped for mounting 
onto plug connector housing 22 in a sliding manner, as indicated by arrow 
"A" in FIG. 1. The device is unitarily molded of dielectric material, such 
as plastic or the like, and includes a top wall 48, a pair of side walls 
50, a rear wall 52 which is irregularly shaped and corresponding to a rear 
wall 53 of plug connector housing 22, and a partial bottom wall 54 of a 
shape which will be clearly seen hereinafter. Each side wall 50 has a 
guide slot 56 which receives guide boss 34 of the plug connector when the 
device is slidably mounted thereon. In particular, the front of each side 
wall 50 rides over the ramped guide surface 34a of the respective guide 
boss 34, and the side wall snaps back into a position against the 
respective side wall 26 of plug connector housing 22, with the guide boss 
positioned in slot 56 (see FIG. 2). 
Top wall 48 of connector position assurance device 20 has a tongue portion 
48a defined by a pair of elongated cut outs 58, whereby the tongue is 
resiliently flexible in the direction of double-headed arrow "B". A latch 
boss receiving slot 60 is formed in tongue 48a, with the front of the slot 
being closed to define a latching surface 60a. When connector position 
assurance device 20 is mounted or assembled onto plug connector housing 
22, the front of tongue 48a of the device rides upwardly over ramped 
surface 36a of preliminary latch boss 36 until latch surface 60a reaches 
the front of the boss, whereupon the resiliently flexible tongue snaps 
down into a preliminary latching position as shown in FIG. 2. 
In other words, the initial step of assembly is to slidably mount connector 
position assurance device 20 onto plug connector housing 22 in the 
direction of arrow "A" (FIG. 1). The connector position assurance device 
initially reaches a first, preliminary position as shown in FIG. 2, which 
could be considered a "preload" position. In this position, it should be 
understood that the device does not block recesses 40 on the underside of 
plug connector housing 22. 
Referring to FIGS. 2 and 3, plug connector 16, with connector position 
assurance device 20 preliminarily mounted thereon, then can be mated with 
socket connector 18 in the direction of arrow "C". The connectors are 
shown in FIG. 3 in a fully mated condition. In this condition, it can be 
seen how projections 44 are fully received in recesses 40 on the underside 
of plug connector housing 22, with the bottom surfaces 44a of the 
projections flush with bottom surface 46 of the plug connector housing. 
FIG. 3 also shows that connector position assurance device 20 still is in 
its preliminary or preload position and is held in that position by 
preliminary latch boss 36. Lastly, it can be seen in FIG. 3 how "partial" 
bottom wall 54 of the connector position assurance device allows a free 
path for projections 44 of socket connector 18 to enter recesses 40 of 
plug connector 16 in the direction of arrow "D". 
FIG. 4 shows the final condition of connector position assurance system 12, 
with plug connector 16 and socket connector 18 fully mated, and with 
terminal position assurance device 20 in its final latched position. More 
particularly, it can be seen in FIG. 4 that the terminal position 
assurance device has been moved forwardly in the direction of arrow "E" 
from the position shown in FIG. 3 to a position wherein latch surface 60a 
of slot 60 has moved over latch boss 38 and into a latching position in 
front thereof. In this final position, it can be seen that partial bottom 
wall 54 of the position assurance device now has moved under projections 
44 of socket connector 18. The socket connector now cannot be unmated from 
the plug connector, regardless of whether or not the connectors are 
designed with a small unmating force. In other words, for inspection, 
servicing and/or replacement purposes, the connectors can be designed with 
a rather small and convenient unmating force, because connector position 
assurance device 20 latches and holds the connectors in their fully mated 
position. 
With the above description and understandings, it can be seen that 
connector position assurance device 20 also acts as a detecting device to 
an operator for indicating that the connectors are not quite fully mated 
under any circumstances. In other words, should the connectors be only 
partially mated, projections 44 of socket connector 18 will not be fully 
inserted into recesses 40 of plug connector 16. The projections, 
therefore, will block movement of the position assurance device to its 
final position by blocking partial bottom wall 54 of the device. Of 
course, once the assurance device is moved to its final position, the 
device, in turn, blocks withdrawal of the projections of the socket 
connector from the recesses of the plug connector. 
Lastly, final latch boss 38 can be designed to determine the amount of 
forces required to move connector position assurance device 20 out of its 
final position to permit unmating of the connectors. Specifically, it can 
be seen that boss 38 is formed with ramped surfaces 38a and 38b on 
opposite sides thereof. Of course, ramped surface 38a, like ramped surface 
36a of preliminary latch boss 36, is provided for facilitating easy 
movement of the position assurance device to its two positions. However, 
ramped surface 38b of boss 38 could be made more abrupt to be more like 
preliminary boss 36. With such a construction, tongue 48 would have to be 
physically lifted in order for latch surface 60a to clear boss 38 and 
allow the position assurance device to be moved back to its preliminary 
position to permit unmating of the connectors. Boss surface 38b has been 
designed, as shown, to be ramped or inclined so that assurance device 20 
can be moved opposite arrow "E" (FIG. 4) simply by pulling rearwardly on 
the device. The inclination of boss surface 38b determines the amount of 
force required for rearwardly moving the assurance device. 
The sectional views shown in FIGS. 5 and 6 (which correspond positionally 
to FIGS. 3 and 4, respectively) clearly show how bottom wall 54 of 
connector position assurance device 20 allows for projections 44 of socket 
connector 18 to enter recesses 40 of plug connector 16 in the direction of 
arrow "D" in FIG. 5. However, once the assurance device is moved to its 
final position, FIG. 6 shows quite clearly how bottom wall 54 
substantially closes recesses 40 and prevents removal of projections 44 
therefrom and, thereby, prevents unmating of the connectors. 
FIGS. 7 and 8 correspond positionally to the depictions of FIGS. 5 and 6, 
respectively. FIGS. 7 and 8 show that partial bottom wall 54 is provided 
with a slot or cutout 70 defining a pair of flange portions 72 of bottom 
wall 54. Slot 70 accommodates socket connector 18 when connector position 
assurance device 20 is moved from its preliminary or preload position 
shown in FIG. 7 to its final position shown in FIG. 8. The flange portions 
72 of partial bottom wall 54, therefore, are the parts of the bottom wall 
which actually block movement of projections 44 of the socket connector 
out of recesses 40 of the plug connector, thereby preventing unmating of 
the connectors. 
Lastly, FIGS. 9-11 show an application of the connector position assurance 
system 12 of the invention, wherein the assurance of proper mating of a 
pair of connectors is quite critical. In particular, socket connector 18 
is shown mounted on an airbag assembly 74 for a motor vehicle. Plug 
connector 16 and cable 30 are electrically coupled to the power and 
control circuitry of the vehicle. FIG. 9 corresponds positionally to the 
condition of the system shown and described above in relation to FIG. 2. 
In other words, plug connector 16 is about to be moved downwardly in the 
direction of arrow "C" into mated engagement with socket connector 18. 
Connector position assurance device 20 is mounted on the plug connector, 
but the device in its first or preliminary position allowing mating of the 
two connectors. 
FIG. 10 shows the system corresponding positionally to FIGS. 3, 5 and 7 
described above. In other words, the connectors are mated, but position 
assurance device 20 still is in its preliminary or preload position. Once 
the devices are fully mated, the assurance device can be moved in the 
direction of arrow "E" to the final, fully mated and latched condition of 
the system as shown in FIG. 11 which corresponds positionally to FIGS. 4, 
6 and 8 as described above. 
It will be understood that the invention may be embodied in other specific 
forms without departing from the spirit or central characteristics 
thereof. The present examples and embodiments, therefore, are to be 
considered in all respects as illustrative and not restrictive, and the 
invention is not to be limited to the details given herein.