Electric connector

The object of the present invention is to provide an electrical connector in which a mechanism for preventing the incorrect insertion of terminals is part of the housing lances so that the incorrect insertion of terminals is prevented. Housing lances 6 are formed in the housing 2 of an electrical connector 1. The housing lances 6 have an inclined surface 8 which protrudes into cavities 4, and recesses 20, which accommodate projections 76 used to prevent the incorrect insertion of terminals 70, are formed in the inclined surfaces 8. Stop surfaces 22 which are contacted by the projections 76 are formed in the front portions of the recesses 20. As a result, further insertion of the terminals 70 is prevented so that incorrect insertion is prevented.

FIELD OF INVENTION 
The present invention concerns an electrical connector, especially an 
electrical connector which has a mechanism for preventing the incorrect 
insertion of electrical terminals. 
BACKGROUND OF THE INVENTION 
Conventionally, projections for the purpose of preventing incorrect 
insertion of electrical terminals have been formed on the terminals as a 
mechanism for detecting upside-down insertion, i.e., the so-called 
incorrect insertion, of the terminals. For example, electrical connectors 
of this type include the connector disclosed in Japanese Patent 
Publication No. 4-220970 as shown in FIG. 4. This electrical connector 100 
has a housing 102 in which cavities 104 that accommodate terminals 150 are 
formed. Housing lances 106 which hold the terminals 150 in the cavities 
104 by engaging with the terminals 150 are formed as part of the housing 
102. The terminals 150 have projections 108 which are located on the 
opposite sides of the terminals 150 from the housing lances 106 when the 
terminals 150 are correctly inserted. These projections 108 are 
constructed so that when the terminals 150 are inserted upside down, i.e., 
when the terminals 150 are inserted into the cavities 104 with the 
projections 108 located on the lower sides of the terminals 150 with 
respect to the position shown in FIG. 4, the projections 108 contact the 
rear surface 110 of the housing 102 so that insertion is impossible. 
Alternatively, in cases where the cavities 104 have large dimensions 
capable of accommodating the projections 108, the projections 108 contact 
the stepped inclined surfaces 112 of double locking members 114 which form 
portions of the housing lances 106, so that further insertion of the 
terminals 150 is prevented. 
In order to allow smooth insertion of the terminals, the portions of the 
housing lances 106 that project into the cavities are sometimes formed as 
gradually inclined surfaces, as for example in the electrical connector 
disclosed in Japanese UM Publication No. 63-37874. In such cases, there is 
a danger that the projections 108 used to prevent incorrect insertion may 
move forward along these gradually inclined surfaces without catching, 
thus passing the housing lances so that the terminals 150 are incorrectly 
inserted. 
SUMMARY OF THE INVENTION 
The present invention was devised in light of the above points. The object 
of the present invention is to provide an electrical connector which 
allows smooth insertion of the terminals thereinto when the terminals are 
inserted in their correct positions and which allows reliable detection of 
incorrect upside-down insertion of the terminals. 
The electrical connector of the present invention is an electrical 
connector which is equipped with a housing provided with cavities into 
which terminals having projections that are used in order to prevent 
incorrect insertion are inserted, and housing lances having inclined 
surfaces that project into the cavities, and by which the terminals are 
held by the housing lances, the electrical connector includes stop members 
which prevent the insertion of the terminals when the terminals are 
inserted into the cavities upside down, as a result of projections on the 
terminals engaging recesses which accommodate the projections, as well as 
front surfaces of the recesses being stop surfaces.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 is a cross-sectional view of an electrical connector 1 of the 
present invention. However, terminal 70 which is connected to an 
electrical conductor 90 is not shown in cross section. The electrical 
connector 1 has a housing 2 in which cavities 4 and housing lances 6 that 
receive terminals 70 are formed. Each housing lance 6 has an inclined 
surface 8 which is gradually inclined and which projects into the interior 
of the corresponding cavity 4. A step section 12, which engages with a 
shoulder 74 formed on contact portion 72 of the corresponding terminal 70 
is formed on a tip portion 10 of each housing lance 6. FIG. 1 shows a 
condition in which a terminal 70 is in the process of being correctly 
inserted into one of the cavities 4. A projection 76 is formed on each 
terminal 70 on the opposite side of the terminal 70 from the corresponding 
housing lance 6. This projection 76 is formed from the metal plate from 
which the terminal 70 is formed by stamping. The front end of the 
projection 76 has a rib shape which is substantially perpendicular to the 
direction of the insertion of the terminal 70. The projection 76 is 
constructed so that when the terminal 70 is correctly inserted, the 
projection 76 moves through a slot 16 formed in a partition wall 14 
located between the cavities 4. A recess 20, which extends in the 
direction of insertion of the terminal 70, is formed in each housing lance 
6. Furthermore, double locking members 40, which secondarily lock the 
terminals 70, are integrally connected to the housing 2 by hinges 42 and 
hold the terminals 70 by pressing against the rear ends 80 of the 
insulation barrels 78 of the terminals 70 with the front ends of the 
double locking members 40. 
FIG. 2 shows a part enlarged view of the undersurface of one housing lance 
6. A recess 20 is formed substantially in the central portion of the 
housing lance 6 with respect to the direction of width of the housing 
lance 6. As is seen from FIG. 1, the recess 20 becomes deeper toward the 
front, and the front end of the recess is closed so that a stop surface 22 
is formed. Recess 20 has a triangular configuration in cross section. Stop 
surface 22 is substantially perpendicular to the direction of insertion of 
the terminal 70. It is sufficient if the width W of the groove 20 is a 
width which allows accommodation of the projection 76; however, this width 
W is narrower than the width of the terminal 70 as seen from the 
undersurface of the terminal 70. This is done in order to allow smooth 
movement of the terminal 70 along the inclined surface 8 without any 
catching of the corner portion 82 at the tip of the terminal 70 in the 
recess 20 when the terminal 70 is inserted correctly. In the present 
embodiment, the width W is set at approximately one half the width of the 
housing lance. Furthermore, this width W may also be set so that it 
gradually increases toward the right in FIG. 2, thus facilitating 
insertion of the projection 76 therein. 
FIG. 3 is a cross-sectional view similar to FIG. 1 which illustrates a 
terminal 70 which has been incorrectly inserted upside down. Since the 
projection 76 is located on the housing lance side of the terminal 70, the 
projection 76 enters the recess 20 of the housing lance 6 and engages the 
stop surface 22, so that further insertion of the terminal 70 is stopped. 
Accordingly, the worker does not receive the standard sensation obtained 
when a terminal is completely inserted; together with the insufficient 
amount of insertion, this lack of the abovementioned standard sensation 
allows the worker to detect the incomplete insertion of the terminal 70. 
An embodiment of the present invention has been described above. However, 
it goes without saying that various modifications and alterations are 
possible within the spirit of the present invention. For example, the 
projection 76 is not limited to a rib-form projection; it would also be 
possible to form the projection by punching the metal plate so that a 
projection is formed. Furthermore, it would also be possible to use a 
multiple number of rib-form projections in order to increase the strength. 
In the electrical connector of the present invention, recesses which 
accommodate projections used to prevent the incorrect insertion of 
terminals are formed in the inclined surfaces of housing lances, and stop 
surfaces are formed which prevent the incorrect insertion of the terminals 
as a result of the projections contacting the front surfaces of the 
recesses. Accordingly, the following advantages are obtained: 
Specifically, the terminals can be smoothly inserted when the terminals are 
inserted correctly, and incorrect insertion can be reliably prevented when 
the terminals are inserted upside down.