Locking security mechanism of electrical connector

A locking security mechanism for an electrical connector having a pair of male and female connector members, locking means and a locking security member mounted in a male connector member in a normally undetachable manner and maintained in a pre-engagement position with a pre-engagement releasing means in a female connector member. When the male and female connector members are engaged with each other, actuating fingers in the female connector member act on a inclined lower surface of pre-engagement fingers in the locking security member to escape the pre-engagement. Locking means in the male connector member comes into engagement with the locking security member unlocked from the pre-engagement state wherein a means for preventing the locking security member from securing in incomplete locking includes a block member provided at the free end of the locking arm member, an enclosure wall portion provided in the main body of the locking securing member for receiving the block member of the locking arm member, and checking lugs provided in the block member and the enclosure portion for abutting with each other.

BACKGROUND OF INVENTION 
1. Field of the Invention 
Present invention relates to an improvement of locking security mechanism 
of connector to be used for the connection of electric wires or the like. 
2. Description of Prior Art 
Usual lock security mechanism of electrical connector, such as shown in 
FIGS. 6 & 7, is provided with a locking arm 3 extending forwardly of the 
outer wall 1 in a male housing M by means of front upright base 2. A 
female housing F has a shell 6 receiving the male housing M and having a 
locking chamber 7 into which the locking arm 3 is inserted. When both 
housings are engaged with each other, an engaging claw 4 at an end of the 
locking arm is engaged with a securing hole 8. In this locking state, an 
unlocking preventing piece 9 is detachably inserted between the outer wall 
1 and the locking arm 3 so that the locking state may be prevented from 
unintentional release. In the drawings, 5 is receiving rooms for terminal 
fittings not shown. Such arrangement is found in Japanese Utility Model 
Preliminary (laid-open) Publication No. 59-29351. 
Prior art locking security mechanisms as such have an arrangement that the 
unlocking preventing piece 9 is attached after the male and female housing 
M, F are engaged with each other. Therefore, it has often occurred that 
during the engagement operation the insertion of the unlocking preventing 
piece 9 is omitted and the omission is difficult to be found later. 
Further, as clearly shown also in the drawings, the unlocking preventing 
piece 9 may be mounted before the male and female housings M, F are 
engaged together. In this case, any undesired state that both housings are 
placed in an incomplete locking position cannot be found easily. Moreover, 
the unlocking preventing piece 9 which is small and separation from the 
housing is apt to occur in cases of inspection or exchange of the 
connector. Such released pieces are difficult to find in the engine room 
of motor-cars or similar locations if lost. 
SUMMARY OF THE INVENTION 
The present invention aims to provide an improved lock security mechanism 
for connectors to prevent the locking arm in the housing from any 
unlocking state by preventing unintentional release of an unlocking 
preventing member and eliminating an incomplete locking state of the 
connector. 
In order to obtain the aim as mentioned, the present invention provides a 
lock security mechanism for electrical connectors having a pair of male 
and female connector members, the male member having a plurality of 
longitudinal compartments receiving terminal fittings and the female 
member that has a rear portion having a plurality of longitudinal 
compartments similar to those of the male member and a front portion 
having a chamber for receiving at least a front portion of the male 
connector member. The locking security mechanism includes a pair of 
locking means respectively provided in the male and female members and a 
locking security means, characterized in that the locking security means 
has a locking security member mounted in one of the male or female members 
in a normally undetachable manner and maintained in a pre-engagement 
position in which it is prevented from coming into a position for securing 
the locking of the locking means and a pre-engagement releasing means 
provided in the other of the male and female members for making the 
locking security member capable of coming into the position for securing 
the locking of the pair locking means when the male and female members are 
engaged.

DESCRIPTION 
Referring to FIG. 1, a female connector member or housing F of synthetic 
material or the like has a rear portion 11 of rectangular box shape having 
six longitudinal compartments receiving terminal fittings (not shown) and 
a front portion 12 of a larger cross section than that of the rear portion 
11 which has a rectangular locking opening 12b in the upper wall 12a 
higher than that of the rear portion 11. The front portion 12 has a 
chamber receiving a male connector member or housing M. In the chamber of 
the front portion 12 are provided two actuating fingers 13, 13 for locking 
engagement which extend forward from the rear wall 12c in a cantilever 
fashion. The actuating fingers 13, 13 have at the free end an arrowheaded 
portion 13a acting on a locking security member M1, detachably assembled 
in the male member M. 
The male connector member or housing M also of synthetic material has a 
rectangular box shape also having six longitudinal compartments connected 
and aligned with those of the rear portion 11 of the female member F when 
engaged together. The male member M has an upper wall 14a provided on the 
upper surface with a locking arm member 15 which has an upright base 
portion 15a at the front end of the wall 14a and a horizontal arm portion 
15e connected with the base portion 15a and extending rearward and apart 
from the upper surface of the wall 14a. The arm portion 15e is provided 
with a lug 15b at the middle portion of its upper surface. The lug 15b has 
an inclined forward face and is engaged with the locking opening 12b of 
the female member F when both engaged. The locking arm member 15 has an 
operating portion 15c at the rear and free end of the horizontal arm 
portion 15e. On both sides of the locking arm member 15 stand vertical 
protection walls 16, 16 extending longitudinally apart from and parallel 
to the arm member 15. 
Behind the locking arm member 15 and between the protection walls 16, 16 is 
disposed a locking security member M1, having a gate shape base 17 and two 
flexible securing fingers 17a, 17a extending from the base along the 
opposite sides of the locking arm member 15. The base 17 has horizontal 
ridges 17b on the inner face of the side walls for preventing the arm 
member from unlocking by the engagement with grooves 15d on the opposite 
side surfaces of the arm portion 15e extending forward from the free end. 
The flexible securing fingers 17a, 17a are formed on the lower surface 
connected with its free end 17a1 with a tapered driven surface 17a2 and an 
escape concave 17a3. The tapered surface 17a2 is formed with an engaging 
concave 17a4 inside its middle portion. 
The locking arm member 15 is on opposite sides of the upright base 15a 
provided with engaging projection 18 having a front tapered surface 18a 
and a rear abutment surface 18b. 
The lock security member M1 is urged to be inserted between the protection 
walls 16, 16 of the male connector member M from behind to engage a 
stepped portion 19 with a support protrusion 20 of the protection wall 16 
which flexes temporally to allow the portion 19 to pass when the free end 
17a1 of the flexible securing fingers 17a, 17a abuts against an abutting 
surface 18b of the engaging projection 18. This is a pre-engaging position 
of the lock security member M1 (FIG. 2). In such a state, when the male 
and female members M, F are engaged, the lug 15b of the locking arm member 
15 is insertedly engaged with the locking opening 12b and the engagement 
unlocking actuating rod 13 provided within the female member F intrudes 
from the lower portion of the engagement projection 18 to the lower 
surface of the flexible securing fingers 17a, 17a thereby allowing the 
actuating projection 13a to raise the free end 17al of the flexible 
securing fingers 17a, 17a by means of the driven tapered surface 17a2 and 
to remove it from the abutting surface 18b of the engaging projection 18 
(see FIG. 3A). 
Next, if the locking security member M1 is further pushed, the unlocking 
preventing portion 17b is engaged with the engagement slit 15d of the 
locking arm portion 15e to restrain the locking arm, and the flexible 
securing finger 17a restores through the escape concave 17a3 when the 
actuating arrowheaded portion 13a of the pre-engagement unlocking 
actuating rod 13 passes the driven tapered surface 17a2, and the engaging 
concave 17a4 and the engaging projection 18 are engaged with each other to 
attain the main engagement in the main position (see FIG. 3C). The free 
end 17a1 of the fingers 17a projects through an opening 12c1 in the rear 
wall 12c of the female member front portion 12 and serves as disengaging 
means in case of unlocking. 
FIG. 4 shows another embodiment according to this invention in which the 
operating portion 15c of the locking arm portion 15e is provided with an 
engagement hole 15d' and the lock security member M1 at the middle portion 
of its base 17 is provided with an unlocking preventing portion 17b' 
insertedly engaged with the engaging hole 15d'. 
FIG. 5 shows a still further embodiment of this invention wherein the 
locking arm portion 15e is an operating portion 15c provided with an 
engaging hole 15d' and an engaging slit 15d" at the bottom wall. The 
locking security member M is at the middle portion of its base 17 provided 
with an unlocking preventing portion 17b' insertedly engaged with the 
engaging hole 15d' and having a riding lock preventing finger 17b" to be 
inserted into the engaging slit 15d". 
As described above, the lock security mechanism according to this invention 
has a lock security member for preventing the male and female members from 
unlocking and is normally undetachably mounted on either of the members in 
a pre-engaging state. Therefore in the engagement operation negligence or 
omission does not happen with ease and incomplete engagement can be 
prevented.