Electrical connector with secondary locking plates

An electrical connector 2, especially intended for automotive applications includes a receptacle connector housing 4 and a mating plug connector housing 6. A movable alignment plate 10 is located between the two connector housings and locking plates 12 are insertable into each housing to provide for additional retention of terminals 100 also held in terminal cavities 34 by resilient latches 50. The connector 2 also includes a cover 8 that is attached to the receptacle connector housing 4 by molded cantilever cover latches 20. Backup beams 28 are movable into engagement with the cover latches 20 for support. Each locking plate 12 is insertable into a locking plate slot 30 on the end of one of the housings and includes recesses 70 into which the molded resilient terminal latches 50, which span the locking plate slot 38, are received when the locking plate 12 is fully inserted. Locking tabs 72, 74, 76, engage the terminals 100 beside the resilient latches 50 provide additional retention of the terminals 100.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is related to electrical connectors and especially to 
electrical connectors used to connect a plurality of wires, such as wires 
in an automotive harness or harnesses. This invention is more particularly 
related to the use of secondary or auxiliary locking members to prevent 
terminals from being dislodged from molded connector housings and to 
prevent disengagement of mating terminals. 
2. Description of the Prior Art 
Although it is important for electrical connectors in all applications to 
establish a reliable electrical termination that will not be disengaged 
under normal operating conditions, automotive applications tend to have 
more problems with failed terminations than many other applications. The 
failure of electrical connectors in automotive applications is not only 
due to the environment in which the connectors are used, but many problems 
have been traced to errors in assembling the electrical connectors and the 
harness in which they are employed. With the increased use of electronics 
in automotive applications these problems can be compounded simply because 
of the additional circuits and wires that must be joined by electrical 
connectors. 
To overcome these problems, electrical connectors used in automotive 
applications have used secondary or redundant locking to prevent terminals 
from being disengaged from the molded housings in which multiple terminals 
are mounted. Terminal position assurance, which means that the electrical 
connector assemblies cannot be assembled if terminals are improperly 
positioned, has been used, and in many prior art connectors, secondary or 
redundant locks cannot be assembled unless the terminals are properly 
seated in the housings. 
One inherent problem with secondary or redundant locking schemes is that 
they inevitably take up space. With the increasing number of wires and 
circuits that must be connected, space often becomes critical. Many 
connectors have a large number of terminals densely packed in a small 
space. It is also common to house terminals of different size in the same 
connector. For example, terminals for supplying electrical power to 
components in an automobile are commonly housed in the same connector with 
a large number of terminals connecting signal wires. Each terminal in 
connectors of this type must be held in position by a molded resilient 
latch engaging the terminal in its terminal cavity and a secondary or 
redundant locking member is used either to ensure that the resilient latch 
does not become disengaged or to independently hold the terminals in the 
connector. When other common problems, such as the tendency of mating 
terminals to stub during mating, the tendency of terminals and connector 
covers to become disengaged when the wires are jerked, and the need to 
insure that connectors can be assembled and mated in only one orientation 
must be solved by connector design, it becomes difficult to meet all of 
these requirements within a given space. 
SUMMARY OF THE INVENTION 
The electrical connector that is the preferred embodiment of this invention 
includes a number of features in one electrical connector design that is 
especially adapted for use in automotive and similar applications. This 
electrical connector is especially adapted for use as a cowl connector in 
an automobile. This connector includes a number of terminals and both 
power and signal terminals are combined in plug and receptacle connector 
housings. Each terminal is held in its terminal cavity by a resilient 
latch that comprises a molded extension of the housing. Redundant or 
secondary latching is provided by locking plates that are insertable into 
the connector housings laterally of the terminals cavities with which 
locking plate slots communicate. Terminals can be loaded into appropriate 
terminal cavities when the locking plates are in a partially inserted 
position because the locking plates include aligned openings though which 
the terminals can be inserted. Locking tabs on the locking plates engage 
each of the terminals when the locking plate is fully inserted. The 
connector also includes an alignment plate that is normally positioned 
between plug and receptacle connectors that guides the tabs of terminals 
into mating socket terminals in the other connector without stubbing as 
blade terminals initially enter into mating socket terminals. A cover is 
also provided on the exterior face of the receptacle connector through 
which the wires exit the connector. This entire connector assembly is held 
together and mating force is supplied by a bolt subassembly connecting the 
two connector housings. 
In addition to each of these features, this connector also provides support 
for latches joining the connector cover to the receptacle connector 
housing without increasing the cross section area or the volume of the 
connector. Backup beams are provided on the movable alignment plate 
located between the two connector housings. These backing beams extend 
through the housing and are positioned behind resilient cover latches when 
the connector assembly is completed. The backing beams insure that the 
cover latches are in engagement with shoulders on the receptacle connector 
housing. In the preferred embodiment of this invention, these backing 
beams are extensions of snap latch beams that extend from the alignment 
plate toward the plug connector housing. These snap latch beams are 
initially held in place on the receptacle housing by protrusions or bumps 
on the receptacle connector. Diamond shaped projections on the plug 
connector housing eventually disengage the snap latches from the 
receptacle connector. This action ensures that the alignment plate remains 
in engagement with the terminal blades as the blades enter the mating 
terminal sockets during initial mating. It also ensures that the backing 
beams will not engage the cover latches during assembly of the cover to 
the receptacle connector housing or until the latter stages of relative 
movement between the plug and receptacle connectors during mating. 
The locking plates also engage the terminals beside the molded cantilever 
housing latches to save space. The width of these molded cantilever 
latches is less than the width of a recess or slot in the locking plate so 
that the latches fit within the locking plate recess. The cantilever 
latches extend from the top of the locking plate slot to a position 
slightly below the locking plate slot where they engage the terminals. 
Locking tabs on opposite sides of the locking plate recess engage terminal 
tabbs that are located on either side of the terminal opening in which the 
molded resilient latch fits to establish primary retention of the 
terminals in the housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The housing components of cowl connector 2 are shown in FIG. 1. This 
connector is primarily intended for use in automotive applications. Cowl 
connector 2 includes two main housing halves, a receptacle connector 
housing 4 and a plug connector housing 6. The connector 2 also includes a 
connector cover 8 that can be attached to an exterior surface of the 
receptacle connector housing 4. A movable terminal alignment plate 10 is 
located between the receptacle connector housing 4 and the plug connector 
housing 6. The conventional purpose of the movable plate 10 is to align 
tabs on terminals, not shown in FIG. 1, during mating to prevent stubbing. 
Similar terminal locking plates 12 and 12' can be inserted into the 
opposite ends of both the receptacle connector housing 4 and the plug 
connector housing 6 to lock the terminals in each connector half in place. 
A bolt subassembly 14 secures the connector assembly 2 in place and 
permits sufficient force to be applied to mate the large number of mating 
terminals contained in this connector. Threads on the bolt assembly 14 
engage companion threads on an insert nut mounted in the tower 30 on the 
plug connector housing 6. In the preferred embodiment, the receptacle 
housing 4 and the plug housing 6 are molded from a conventional 
thermoplastic, such as PBT. The connector cover is also molded from a 
conventional thermoplastic, such as polypropylene. The movable alignment 
plate 10 and the terminal locking plates 12 are also molded from a 
conventional thermoplastic, such as PBT, and preferably have a distinct 
color so that it is easy to determine if they are in their correct 
positions. 
Conventional stamped and formed terminals, such as terminals 100 would 
typically be used in this connector 2. These terminals would be attached 
to insulated wires. Larger terminals 100, suitable for carrying currents 
transmitting relatively larger electrical power, and attached to 10-12 AWG 
wires are inserted into terminal cavities 34 in the receptacle connector 
housing 4 and similar corresponding cavities in the plug connector housing 
6. These terminal cavities 34 are located along opposite sides of both 
connector housings. Other terminals suited to carry signal currents can be 
mounted in terminal cavities 36 that are located between the larger 
terminal cavities 34 and along the ends of the connector housings. 
Prior to inserting terminals attached to wires into the two connector 
housings, the locking plates 12 and 12' are first partially inserted into 
the locking plate slots 38 on opposite ends of both connector housings. As 
shown in FIG. 6, each locking plate includes openings 80, 82 and slots 70 
that can be aligned with corresponding terminal cavities 34 and 36 when 
the locking plates are partially inserted into the corresponding locking 
plate slots 38. With the locking plates in this partially inserted 
position, terminals can be inserted into the terminal cavities 34, 36 and 
through the aligned openings 80, 82 and slots 70. Signal terminals can 
similarly be inserted into terminal receiving cavities 36 with the locking 
plates in the partially inserted position. 
The movable alignment plate 10 is positioned on the interior surface of the 
receptacle connector housing 4, and then the terminals are positioned in 
the connector housings 4, 6, with the locking plates 12 are located in 
their partially inserted positions,. Tabs on terminals 100 are received 
within slots on the movable alignment plate 10. The movable alignment 
plate 10 includes alignment posts 22 located on each of its four corners. 
These alignment posts 22 are received within grooves 58 located at the 
four corners of the receptacle connector housing 4 as shown in FIG. 2. A 
number of beams 24 extend between the posts 22 in the opposite direction. 
Clearance for these beams 24 is provided by channels 54 located along the 
sides of the receptacle connector housing 4. The beams 24 located adjacent 
to the posts 22 at either end of the movable plate 10 include an outwardly 
directed inclined surface 26 and a latch backup section or backing beam 28 
extending from the movable plate 10 on the same side as the posts 22. The 
latch backup sections or backing beams 28 are spaced from the posts 22. 
The outermost beams including inclined surfaces 26 also have snap 
protrusions 60 located on their lower ends as seen in FIG. 3. Snap 
protrusions 60 are also located on adjacent beams 28 with adjacent snap 
protrusions being opposed. A protruding retaining boss 62 located on the 
interior of receptacle housing shroud 44 engages the top of these snap 
protrusions 60 to hold the movable plate 10 in an extended position to 
stabilize the ends of the terminals for initial mating. As the plug 
housing 6 moves closer to the receptacle housing 4, after initial 
engagement of mating terminals, diamond shaped camming surfaces or 
protrusions 63, located on the sides of the plug housing 6, engage aligned 
snap protrusions 60 and force them apart. The snap protrusions 60 are then 
freed from the retaining bosses and the movable alignment plate 10 shifts 
upward until it engages the inwardly facing mating surface 42 of the 
receptacle housing 4. As the plug and receptacle connector halves are 
mated by the bolt assembly 14, the movable alignment plate 10 moves toward 
the interior surface 42 of the receptacle connector housing 4. Alignment 
plate 10 remains parallel to the interior surface 42 of the receptacle 
connector housing 4 because the posts 22 are stabilized by the grooves 58 
in which the posts 22 travel. This rectilinear movement of plate 10 keeps 
the tabs on male terminals 100 and other terminals in a proper orientation 
to prevent stubbing with mating terminals during connector mating. 
Alignment posts 88, shown in FIGS. 7 and 15 extend downward on the lower 
surface of the receptacle connector housing 4 and through compatible 
openings in the movable alignment plate 10. As shown in FIG. 15, these 
alignment posts 88 include a keying extension 90 projecting at an angle 
from a lower corner of the otherwise I-shaped cross section of the post 
88. This cross section permits the posts to fit between closely spaced 
terminal cavities in this heavily populated connector. The alignment plate 
10 is keyed relative to the tower so that it can only be attached to the 
receptacle connector housing 4 in one orientation. The plug connector 
housing 6 would also included similarly shaped openings to receive the 
keyed posts 88 so that the two connector housings 4, 6 and the alignment 
plate 10 could only be assembled in one orientation. 
The connector cover 8 is mounted on the top of the connector assembly, or 
more precisely over the accessible side of the connector 2. Insulated 
wires 112 extend up from terminals located in the receptacle connector 
housing. The wires 112 are routed away from the connector 2 under the 
cylindrical extension 18 extending from one side of the connector cover. 
Cover 8 includes resilient cover latches 20 extending downward adjacent to 
the four corners of the cover. These molded resilient latches 20 are 
tapered from the root toward the latch ends so that the cantilever latches 
are both flexible and have sufficient strength to prevent breakage. Each 
latch 20 includes a conventional snap lock 21 on the end. These snap locks 
have downwardly facing inclined camming surfaces and upwardly facing 
locking surface so that the latch is cammed outwardly over a protrusion 
during movement from the position shown in FIG. 4 to the position shown in 
FIG. 5 where the latch snaps back to its neutral locking position. As 
shown in FIG. 5, the snap lock 21 engages an opposed locking surface or 
shoulder 56 along the side of the receptacle connector housing 4. Although 
this snap lock engagement is sufficient to secure the cover 8 to the 
receptacle connector housing 4 under typical conditions, sufficient force 
can be applied to the cover to overcome this conventional latching 
engagement. Especially in automotive applications, this force can be 
transmitted to the cover 8 when the wires leading from extension 18 are 
pulled or moved. Disengagement of the cover 8 in this manner is 
undesirable. To restrain or reinforce the latch 20 and to prevent the snap 
lock 21 from being disengaged from the locking shoulder 56, the adjacent 
side beam 24 extends above the base of the movable plate 10 to form a 
support or backing beam 28 for the latch 20. Support 28 in the form of an 
upwardly extending beam includes an inclined surface 26 at its lower end 
and the end of support beam 28 is positioned and configured to engage the 
back surface of the latch 20 behind the snap latch 21. Snap latch 21 is 
thus assured of its position with respect to the shoulder 56 and the latch 
cannot become disengaged by forces applied to the wire 112 or to the cover 
8. As previously discussed, the movable plate 10 is not moved upward until 
the last part of the connector mating operation because the engagement of 
snap tabs 60 by protruding bosses 62. Therefore the support beam 
extensions 28 are not moved into position adjacent to the back of latches 
20 until the latter stages of the mating engagement. Cover 8 must 
therefore be attached to the receptacle connector housing 4 prior to the 
time that the two connector halves are mated. Cover 8 could be attached 
before the receptacle connector housing 4 is aligned with plug connector 
housing 6. Alternatively, the cover 8 can be attached after the two 
connector halves are attached and aligned and before mating. In either 
case, protruding nubs on the cover engage the housing to prevent rotation 
or cocking of the cover relative to the connector housing so that the 
latches are not overstressed. 
The manner in which the terminals 100 are held in the receptacle connector 
housing 4 is shown in more detail in FIGS. 6-14. Although only the larger 
terminals 100 and the receptacle connector housing 4 are shown and 
discussed in detail, it should be understood that the manner in which 
these terminals are retained in this housing is representative of the 
terminal retention in the plug connector housing 6 and the terminal 
retention for the signal terminals in terminal cavities 36. The stamped 
and formed blade terminals 100 are inserted into terminal cavities 36 in 
the receptacle housing 4. Mating stamped and formed socket terminals, not 
shown, are inserted into companion terminals cavities in the plug 
connector housing 6. Both the blade terminals 100 and the mating socket 
terminals are of conventional constructions and can be stamped from a 
conventional material, such as phosbronze, and are plated in a 
conventional manner. These terminals are generally referred to as crimp 
snap terminals. 
Terminal 100 has a mating blade 110 at one end of the terminal and a crimp 
barrel 108 at the opposite end. The crimp barrel 108 is crimped or formed 
around an uninsulated end of a wire 112 to form a permanent electrical 
connection. This termination can be performed on a number of high speed 
machines. Each terminal 100 also includes latching surfaces between the 
crimp barrel 108 and the blade 110. The primary latching surface is an 
opening 104 that is configured to receive a molded resilient latch 50 
protruding into the corresponding terminals cavity 34 from one end. The 
molded latch is cammed outwardly upon insertion of the terminal 100 and 
then returns to its neutral position when the terminal 100 is located so 
that the latch 50 can enter the terminal opening 104. Each terminal 100 
also includes a latching tab 102 that protrudes outwardly beside the 
opening 104. This latching tab 102 is positioned for engagement with a 
surface on the secondary locking plate 12 that is inserted into its final 
position after the terminals 100 and signal terminals have been seated in 
engagement by the corresponding resilient latch. 
One of the secondary locking plates 12 is best seen in FIG. 6. Locking 
plates 12 are flat molded members that can be inserted into slots 38 that 
open on both ends 46 of the receptacle connector housing 4. Similar 
locking plate slots open on the ends of the plug connector housing 6. The 
locking plate slots 70 intersect the terminal cavities 34 in the connector 
housing 4. Each locking plate 12 has a central section 66 with two 
cantilever arms 68 located on the ends of the plate 12. The arms 68 are 
separated from the central section 66 by recesses or slots 70. Recesses or 
slots 70 in turn have inset openings 80 that extend from each side of the 
corresponding slot 70 to provide clearance for a terminal 100 to pass 
through the clearance opening 80 when the clearance opening is positioned 
in alignment with a corresponding terminal cavity 34. A number of signal 
terminal openings 82 are located in the central plate section 66. These 
signal terminal openings are in turn large enough to permit insertion of a 
signal terminal when the signal terminal opening 82 is properly positioned 
relative to a corresponding signal terminal opening 36. 
A series of locking tabs 72, 74, 76 are formed along the arms 68 and on the 
edges of the central section 66 in the terminal openings through which 
terminals 100 are to be inserted. Each of these locking tabs has a 
thickness that is less than the thickness of the remainder of the locking 
plate 12 and has a tapered cross section. Locking tabs 72 extend from the 
ends of the arms 68 while the locking tabs 74 and 76 extend into the 
respective clearance openings 80. Each of the signal terminal clearance 
openings 82 also includes a similar locking tab 78 extending inwardly form 
one edge. Each of the locking tabs 74, 76 and 78 extend from the clearance 
edge opening adjacent to the base of the locking plate 12 toward the free 
end of the locking plate 12 and the cantilever arms 68. Despite the 
presence of the various locking tabs, the respective clearance openings 
are still large enough to permit insertion of the corresponding terminal 
into the respective terminal cavity and through the clearance opening when 
the locking plate 12 is in the partially inserted position. The locking 
plate 12 also has resilient fingers 92 located along the base. These 
resilient fingers 92 engage opposed surfaces at the top of the locking 
plate slot 38 to hold the locking plate 12 initially in the partially 
inserted position where the clearance openings are aligned with 
corresponding terminal cavities to permit insertion of the terminals into 
the slots and a final position, shown in FIG. 9, in which the locking tabs 
engage terminal latching tabs 102 to provide a secondary or redundant lock 
holding the terminals in their respective housings. 
The locking tabs 72, 74, 76, and 78 are brought into engagement with 
latching tabs on respective terminals, such as latching tab 102 on the 
larger power terminals 100, by pushing the locking plates 12 further into 
the locking plate slots 38. When the locking plates 12 are full inserted, 
the locking tabs extend into the terminal cavities and are positioned over 
surfaces on the terminal, such as latching tab 102 on terminals 100. The 
terminals cannot then be pulled out of their respective terminal cavities 
because that would require not only destruction of the molded resilient 
terminal latches 50 and 52, but also the locking tabs 72, 74, 76 and 78. 
FIGS. 12, 13, and 14 show the relative position of a terminal 100, a 
resilient latch 50, a locking plate 12 and a locking tab 72 on the end of 
arm 68. The section shown in FIG. 12 is taken through the resilient latch 
50 and the terminal latch opening 102 in which it fits. The latching slot 
38 is shown in phantom. FIG. 13 shows a section that is parallel to the 
section shown in FIG. 12. This section extends through the locking tab 72 
on the front of the locking plate 12. The section shown in FIG. 13 is 
offset from the resilient latch 50 shown in FIG. 12 and this resilient 
latch will fit in the recess or slot extending between the cantilever arm 
68 and the central section 66 on the locking plate 12. The tapered shape 
of the locking tab 72, and of the other tabs 74, 76 and 78 on the locking 
plate 12 is shown in FIGS. 13 and 14. The locking plate 12 and the locking 
tab 72 on the front of the cantilever arm 68 is shown in the partially 
inserted position in FIG. 13, and the terminal cavity is not obstructed by 
the locking tab 72. FIG. 14 shows the same section view as in FIG. 13, but 
the locking plate 12 has now been moved to the fully inserted position 
shown in FIG. 9. The tapered locking tab 72 is positioned above the 
terminal tab 102 in FIG. 14. In this position the locking tab 72 provides 
a secondary or redundant lock for the terminal 100. 
FIGS. 7, 8 and 12 show the profile of the resilient latches 50 and their 
position relative to the locking plate slot 38. Each of these resilient 
latches used to restrain one of the larger terminals, such as terminal 
100, extends at least partially through the locking plate slot 38. These 
cantilever latches 50 extend from a post, of rectangular cross section, 
that extends between portions of the housing on opposite sides of the slot 
38. As seen in FIG. 7 the molded resilient latches are flexible cantilever 
beams with the root section located within the locking plate slot 38. The 
free end of each molded resilient latch 50 is located below the locking 
plate slot 38. As also seen in FIG. 7, the length of the molded resilient 
latches 50, positioned toward the middle of the connector, is less than 
the length of the outermost resilient latches 50. Latch 50 extends to the 
top of the locking plate slot 38. The width of each of the molded 
resilient latches 50 is less than the width of the recess or slots 70 
separating the arms 68 on the locking plate 12 from the central locking 
plate section 66. Therefore these molded resilient latches 50 on the 
receptacle housing 4 fit within the recesses 70 when the locking plate 12 
is moved into position. This configuration can be seen by comparing FIG. 
12 with FIGS. 13 and 14 which show that the locking tabs 72 engage the 
terminal tabs 102 beside the engagement of the molded resilient latch 50 
with terminal opening 104. The same relationship applies to locking tabs 
74, 76 and the other molded resilient latches 50 This relationship is also 
found in the mating socket terminals, locking plates and molded resilient 
latches employed in the mating plug connector housing 6.