Pluggable electrical connection block and connector incorporating such a block

A pluggable electrical connection block comprises a rectangular housing having parallel sideways therein and a plurality of flat slabs of elongated cross-section made of insulating material, each in one slideway. Each slab is formed with a single row of parallel passages for receiving respective contact terminals and has a major face cut out to constitute individual resilient retaining detents for engaging holes in the terminals. The housing and slabs have a slidable keying connector. The projections defining the slideways are formed throughout the entire depth of the housing so as to guide each slab from the moment it is inserted in the housing. The detents are placed short of the front end of the respective slab. The housing has a step formed internally on one of the major sides for coming into abutment against any raised detent.

BACKGROUND OF THE DISCLOSURE 
The invention relates to electrical connectors having two connection blocks 
that are pluggable into each other, and it relates more particularly to a 
connection block for such a connector which is of the so-called "modular" 
type. The connector comprises a rectangular housing with two opposite 
faces having longitudinal projections that delimit parallel sideways and 
flat slabs of insulating material, each slab occupying one of said 
slideways and including a single row of parallel passages for receiving 
contact terminals, and having a large face cut out in a front portion 
thereof to constitute individual retaining detents for the terminals that 
engage in holes in the terminals, the housing and each slab including 
cooperating keying means that allow a slab to be fully inserted in one 
orientation only. 
A block of the above-defined kind can easily be designed to incorporate 
slabs giving contact terminal distribution pitches that vary from one slab 
to another (but naturally are equal for the two cooperating slabs of the 
two blocks of a same connector). It is also possible to omit some of the 
slabs in applications where the corresponding terminals are not required. 
All of these features make such a connector particularly advantageous in 
numerous fields, including the automotive industry and workshops using 
electronically controlled machine tools and/or robots. 
Existing connection blocks of the above-defined type have some drawbacks. 
In particular, it happens that slabs are forced into position even when 
one of the terminals carried thereby has not been fully pushed home and 
has not snapped into place, either because forward movement of the slab 
causes the detent to be pushed back inwardly, or else because the detent 
is folded to such an extent that it breaks. In either case the terminal is 
no longer retained once the slab has been inserted. 
SUMMARY OF THE INVENTION 
An object of the invention is, in particular, to avoid this risk. To this 
end it provides a connection block of the above type, characterized in 
that the projections occupy the entire depth of the housing so as to guide 
each slab from the moment it is inserted in the housing, in that the 
detents are set back from the front of the slab, and in that the housing 
includes a step on one of its large sides that comes into abutment against 
any detent of the slab that is lifted because a terminal of the slab is 
not fully pushed home, thereby limiting the bending deformation of a 
detent. 
By guiding the slab accurately from the moment it starts to be inserted, it 
is guaranteed that any detent raised by a terminal comes into abutment 
against the step and slides thereon until it abuts the shoulder limiting 
it. The operator is then warned with certainty and is led to check the 
terminals. 
It is also possible to form an abutment step on the back of each slab, on 
the major face thereof opposite to the major face in which the detents are 
cut out, thereby causing each slab to protect the following slab against a 
failure to snap in place. 
It may also be observed that once all of the slabs are in place (even if 
the first slideways only are occupied), then all of the detents are 
retained and are prevented from rising. 
The invention is particularly advantageous in connectors whose male 
terminals are blades whose width extends in the row direction and in which 
the female terminals are of the cage type. Under such circumstances, the 
housing of each block advantageously has side walls interconnected by a 
bottom which is formed with rows of slots each corresponding to a location 
for a slab; by making the slots longer than the spacing between two 
passages, it is possible to place slabs in the housing having any one of 
several different distribution spaces for use with terminals of different 
sizes in the row direction: for example, female terminals can be used that 
are 2.8 mm wide and that are 1.5 mm wide, respectively distributed at 
spacings of 5 mm and 3.33 mm (i.e. so that three closely spaced terminals 
occupy the same length as two large spacing terminals). 
The slabs must be held in place. This can be achieved by external means. 
However, in an advantageous embodiment, each of the small faces of each 
slab carries a resilient retaining finger having at the rear thereof a 
catch for engaging in an opening in the housing, the finger being 
straddled by two rigid wings. The wings prevent jamming of the finger, 
e.g. by a wire engaged between the finger and the body of the slab. 
To avoid the risk of slabs for male terminals (blades) being installed in a 
housing for receiving slabs of female terminals (cages), the keying means 
may include on a single one of the small faces of each slab, a groove or a 
rib placed on one side of the mid plane for one type of slab and on the 
other side for the other type; a single one of the faces of the housing 
includes grooves or ribs in a corresponding location. The keying means 
thus perform two functions. 
The invention will be better understood from the following description of 
particular embodiments of the invention given by way of non-limiting 
example. The description relates to the accompanying drawings:

DETAILED DESCRIPTION 
The male connection block 10 shown in FIGS. 1 to 3 is intended to receive 
cage type female terminals and to be plugged into a mating female 
connection block 12 (FIG. 6) fitted with male terminals comprising contact 
tongues or blades. Such a block is usable, in particular, on motor 
vehicles. 
The block 10 comprises a housing 14 for receiving one or two slabs 16 (the 
housing possibly being designed to receive a larger number of slabs). The 
housing 14 and the slabs 16 may be made of a polymerised synthetic 
material containing fillers. 
The housing 14 is rectangular in cross-section and has sides that are 
interconnected by an end wall which is formed with rows of parallel slots 
17. It includes means defining slideways for guiding slabs 16 from the 
moment they are inserted. For a two-slab housing, these means comprise a 
single pair of guide projections 18 formed along two opposite sides of the 
housing, together with pairs of guide steps 20 situated where the large 
sides meet the small sides of the housing, all of constant cross-section 
corresponding to the cross-section of grooves formed in the edges of the 
slabs. 
In each of the slabs, of elongate rectangular cross-section and of a 
thickness such that the slabs leave only a small gap therebetween and with 
the housing, there is formed a row of a plurality of rectangular section 
passages each intended to receive a terminal 22 (FIGS. 1 and 9). The fully 
engaged position of each terminal is determined by its coming into 
abutment against an abutment rim 24 provided on the slabs. 
One of the major faces of each slab is cut out to form resilient detents 26 
whose catches are designed to engage into one of two abutting holes 28 
provided in each terminal, on two opposite sides. The detents 26 terminate 
short from the front end of the slab and from the abutment rim 24. The 
detent extends beyond the catch so that its bending causes its end to move 
further than the associated displacement of the catch, this constituting a 
factor that facilitates detecting non-engagement. 
In the front portion of a single one of the small faces of each slab 16, a 
keying groove 30 is provided which is offset from the mid-plane of the 
slab and intended to slide over a keying rib 32 provided on only one side 
of the housing 14. By using opposite offsets for slabs of male blocks and 
female blocks, not only a reversed insertion of the slabs in a housing is 
avoided, but also any error as to the housing is avoided. 
If a terminal 22 is not completely pushed home, it is not locked in place. 
The corresponding resilient detent 26 therefore projects laterally. To 
ensure that it is then impossible to put the slab into place, a step 34 is 
cut into that one of the major sides of the housing which faces the 
detents of the first slab (FIGS. 4 and 6). Thus, any detent raised by any 
incompletely inserted terminal comes into abutment against the shoulder of 
the step and jams against the shoulder of the step. This abutment is 
certain to occur because the slab is guided from the beginning of its 
insertion while the end of the detent 26 is offset back. 
The housing is involved for preventing insertion of the first slab only in 
the event of one of the detents thereof remains projecting outwards. Means 
are advantageously provided to prevent insertion of the second slab 
likewise and possibly of further slabs. In the example shown in FIG. 6, 
these means are constituted by a step 36 on each of the slabs. 
In the block shown by way of example in FIGS. 1 to 6, the slabs are held in 
place individually. To do this, each of the small faces of each slab is 
cut out to constitute a resilient finger 38 having a locking catch for 
engaging in a corresponding opening 40 in the housing 14. In order to 
avoid any risk of a finger 38 jamming in projecting position, e.g. by a 
wire becoming inserted between the Figure and the body of the slab, each 
finger 38 is advantageously disposed between two side protective wings 42 
(FIG. 2). The means enabling the male block to be fixed to the female 
block may include extensions 44 that engage between the fingers 38 and the 
bodies of the slabs, thereby preventing the slabs from being withdrawn. 
FIGS. 7 and 8 show other embodiments in which the steps 36 for preventing 
insertion of slabs other than the first, should a detent remain raised, 
are replaced by other means. 
In FIG. 7, the partitions of each slab separating the passages therein are 
provided with respective sloping edges 46, and that one of the major faces 
of the slab which does not carry detents terminates about two thirds of 
the way along the slab so as to constitute a support shoulder 48. 
In the case shown in FIG. 8, the housing 14 has short walls 50 whose ends 
constitute abutments. 
A connector may be constituted by a male block of any one of the types 
described above and by a female block 12 of the type shown in FIG. 6. This 
female block also includes sides and an end wall 52 which in this case is 
at a distance from the entrance of the block. The slots 17 formed in the 
bottom wall of the housing 14 and the slots 54 in the bottom wall 52 are 
placed so that they coincide. They are wide enough to be able to pass the 
tongues of male terminals 56 retained in the slabs of the female block 12 
and they are long enough to occupy the major portion of the length of the 
row of slots. FIGS. 3 and 5 show, by way of example, rows of three slots 
17, whereas the housing 14 is capable of receiving slabs having six 
passages. This disposition of slots makes it possible to place any one of 
several types of slab having passages of different transverse dimensions 
and having different numbers of passages in a given housing. Thus, 
depending on the electric current to be passed, slabs can be provided for 
terminals having a contact zone of width 1 that varies from one slab to 
another, while they all have the same thickness. 
To increase the strength of the blades of the male terminals 56, these 
terminals may be constituted by folding metal sheet to double the 
thickness of the blade and then by cutting out the ends of the blades.