Abstract:
An inertial locking connector is provided, by which the appropriation of a normal connector is improved and an incomplete engagement of the connectors is securely prevented from occurring. The inertial locking connector includes: a first connector housing provided with a locking arm having a locking projection; and a second connector housing provided with an engaging projection, which engages with the locking projection, wherein upon engaging of the first and second connecor housings, a front end face of the locking projection is situated facing a perpendicular front end face of the second connector housing and the front end face of the locking projection abuts against the front end face of the second connector housing. Thereby, the inertia force upon the engagement of the connectors is exhibited.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     This invention relates to an inertial locking connector, which engages connectors with each other by using the inertia force and, more specifically, to an inertial locking connector, which can appropriate a known non-inertial locking connector for one of a pair of the connectors. 
     (2) Description of the Related Art 
     FIG. 9 illustrates an example of a conventional inertial locking connector. 
     The conventional inertial locking connector consists of a male connector  44 , which receives female terminals  43  in its block-shaped housing  42  (a part for receiving terminals) inside a hood part  41 , and a female connector  47 , in which tabs of male terminals  46  are protruded in a connector engaging chamber  45  mating with the housing  42 . In this specification, a connector having the block-shaped housing  42  is defined as a male connector, while a connector having the connector engaging chamber  45  is defined as a female connector. 
     A connector housing of the male connector  44  consists of the outside hood part  41  and the inner housing  42 , which are integrally molded using synthetic resin. A flexible locking arm  50  is integrally formed with an upper wall  48  of the inner housing  42  through a holding part  49 , which is situated at the middle of the length direction of the locking arm  50 . The front half of the locking arm  50  is located inside of the hood part  41 , while an operating part  51  of the rear half of the locking arm  50  is exposed outward from an opening  52  of the hood part  41 . 
     A locking projection  53  is formed downwardly at a front end of the locking arm  50  and a front end face  53   a  of the locking projection  53  is an abutting face, which is formed approximately perpendicular or inclined facing front with regard to the female connector  47 . There is provided a terminal receiving chamber  54  in the inner housing  42 , in which a female terminal  43  having wires is received. The female terminal  43  has a box-shaped electric contact part (indicated by the abbreviation numeral  43 ) having a resilient contact piece (not shown in the figure) therein, which mates with the tab of male terminal  46 , and a solderless contact part  56 , to which a wire  55  is connected and fixed. A hole at the central part of the electric contact part ( 43 ) of the female terminal  43  is locked by a flexible locking lance  57 . 
     A waterproof rubber stopper  58  is inserted on the wire  55 , while the outer periphery of the waterproof rubber stopper  58  adheres closely to the rear inner surface of the terminal receiving chamber  54 . A waterproof packing  59  for the female connector  47  is provided on the outer base of the inner housing  42 . 
     In the female connector  47 , a pair of guide walls  62  for the locking arm  50  are formed at both sides on an opper wall  61  of the connector housing  60 , which forms the connector engaging chamber  45 , while an engaging projection  63  engaging with the locking projection  53  is formed between a pair of the guide walls  62 . The engaging projection  63  has a front end face (abutting face)  63   a , which faces the front end face  53   a  of the locking projection  53  and is inclined a little backward, and a perpendicular rear end face (engaging face)  63   b,  which engages with a rear end face (locking face)  53   b  of the locking projection  53 . 
     The tab at the front half of the male terminal  46  protrudes in the connector engaging chamber  45 , while the rear half of the male terminal  46  is received into a terminal receiving chamber (not shown in the figure) of the connector housing  60  and continues to a wire (not shown in the figure). Otherwise, the connector housing  60  is integrally formed with an instrument and the like, and one side of the plate-shaped male terminal  46  that has a tab at an oppsite side thereof continues to a busbar and the like at the instrument side. 
     When an operator starts to fit the connecors  44  and  47  to each other starting from the state shown in FIG. 9, both ends of the male and female terminals,  46  and  43 , respectively, come into light contact with each other and at the same time the front end face  53   a  of the locking projection  53  of the locking arm  50  strongly abuts against the front end face  63   a  of the engaging projection  63 . Then, the operator pushes both connectors  44  and  47  in the engaging direction with a strong force, resulting in that the front end face  53   a  of the locking projection  53  slides upward along the front end face  63   a  of the engaging projection  63  so as to bend the locking arm  50 , the abutting between both projections  53  and  63  is released, and both connectos  44  and  47  are engaged with each other by force with the aid of the inertia force thereof. When the locking projection  53  climbs over the engaging projection  63 , the locking arm  50  restores to the original state with shifting downward and the rear end face  53   b  of the locking projection  53  abuts against the rear end face  63   b  of the engaging projection  63 . 
     Thereby, both connectors  44  and  47  are locked together, preventing both connectors from coming off abruptly. This connector engagement using the inertia force thereof exhibits a secure engaging force even when an insertion force of the male or female terminal ( 46  or  43 ) is large (especially when the number of the terminals is large) and when the inner periphery of the connector housing  60  adheres closely to the outer periphery of the waterproof packing  59 . 
     However, according to the structure of the conventional inertial locking connector, when the operator uses an insufficient force to fit the connecors  44  and  47  to each other, there is the possibility that both connectors stop staying in half engaged condition (i.e. incomplete engaged condition) in a state that the locking projection  53  of the locking arm  50  of the connector  44  climbs on the engaging projection  63  of the connector  47 . In this case, since both terminals  46  and  43  are inserted by as long as about half of the regular stroke, both connectors  44  are tentatively held with each other without coming off, therefore there is the possibility that the operator judges that both connectors are completely engaged with each other and advances it to the next process. 
     Further, not to mention the locking arm  50 , the engaging projection  63  needs a machining to enlarge the incline of the front end face  63   a  for the purpose of the inertial locking, forcing both connectors  44  and  47  to be exclusively manufactured as the inertial locking parts. Furthermore, a normal connector, which does not implement the inertial locking, can be neither appropriated nor compatible with the inertial locking part, causing an uneconomical situation. Furthermore, since the rear end face  53   b  of the locking projection  53  slides against the rear end face  63   b  of the engaging projection  63  with a strong force upon the engagement of the connectors, when the engaging and coming off operations are implemented repeatedly, each projection  53  or  63  is worn down and deformed, causing the possibility that the locking force deteriorates and that a large inertial force cannot be obtained, that is, the inertial locking is not implemented. 
     SUMMARY OF THE INVENTION 
     It is therefore an objective of the present invention to solve the above problem and to provide an inertial locking connector, by which the incomplete engagement of the connectors due to that the locking projection climbs on the engaging projection to stop there is prevented from occurring, and the appropriation and compatibility of the connector are improved, and the deterioration in the inertial force and the locking force due to the deformation and wear of the locking and engaging projections are prevented from occurring. 
     In order to attain the above objective, a first aspect of the present invention is to provide an inertial locking connector comprising: a first connector housing provided with a locking arm having a locking projection; and a second connector housing provided with an engaging projection, which engages with the locking projection, wherein upon engaging of the first and second connecor housings, a front end face of the locking projection is situated facing a perpendicular front end face of the second connector housing and the front end face of the locking projection abuts against the front end face of the second connector housing. 
     The front end face of the locking projection is formed inclined by an appropriate angle equal to or less than 90° in response to the magnitude of the inertia force. 
     There is provided a distance between the front end face of the second connector housing and the engaging projection thereof for the locking projection to slide. 
     Upon engaging of the first and second connecor housings, the locking projection climbs over the engaging projection to complete the engagement between the locking projection and the engaging projection, with the locking arm being bent. 
     According to the first aspect of the present invention, since the locking projection of the locking arm of the first connector housing abuts against the front end face of the second connector housing, when an operator presses both connector housings in the engaging direction thereof with a strong force, the locking arm is bent and at the same time the inertia force is exhibitted in the engaging direction of the connectors, the locking projection of the locking arm advances powerfully toward the engaging projection situated more rear compared to the front end face of the second connector housing. Therefore, there is no possibility that both connectors stop staying in half engaged condition (i.e. incomplete engaged condition) in a state that the locking projection of the locking arm of the first connector climbs on the engaging projection of the second connector, thereby the connectors are securely engaged and locked with each other. 
     Further, since the engaging projection of the second connector housing needs no construction (for example, to make the angle of the front end face of the engaging projection have a steep slope) for the inertial locking, a normal connector that is not for the inertial locking can be employed as the second connector, thereby decreasing the cost of parts. In addition, as a normal connector, a plurality of kinds of connector can be compatible with each other from the viewpoints of presence or absence of the waterproof rubber stopper and different total length of the connectors, thereby the degree of freedom for disposing position of the connectors and for connection form thereof is increased. 
     Furthermore, upon the connector engagement, the locking projection of the locking arm strongly abuts against and slides on the front end face of the connector housing, therefore the locking projection does not strongly press the engaging projection, thereby the deformation and wear of the engaging projection are prevented from occurring and the locking force does not deteriorate even when the connectors are repeatedly engaged with and separated from each other. Since the locking arm bends by a pressing force having a specified magnitude, the deformation and wear of the locking projection do not take place. Since the front end face of the connector housing has a high stiffness in the abutting direction, the front end face neither be bent, deformed, nor worn by abutting against the locking projection of the locking arm, therefore a large inertia force is exhibitted. 
     A second aspect of the present invention is to provide an inertial locking connector comprising: a first connector housing provided with a locking arm having a locking hole; and a second connector housing provided with an engaging projection, which engages with the locking hole, wherein upon engaging of the first and second connecor housings, a perpendicular front end face of the locking arm is situated facing a front end face of the engaging projection and the front end face of the locking arm abuts against the front end face of the engaging projection. 
     The front end face of the engaging projection is formed inclined by an appropriate angle equal to or less than 90° in response to the magnitude of the inertia force. 
     According to the second aspect of the present invention, since the locking arm is provided with not the locking projection but the locking hole, upon the engagement of the connectors, the front end of the locking arm abuts against the engaging projection, and when the locking arm bends so that both connectors engage with each other by the inertia force, the locking hole slides well with regard to the engaging projection compared to the case of the locking projection, thereby there is no possibility that the front end of the locking arm climbs on the engaging projection to stay there, that is, the incomplete engagement of the connectors never takes place. Further, since there is no locking projection, there is no problem of the wear and deformation of the locking projection. The locking is implemented in a state that upon the engagement of the connectors the locking hole engages with the engaging projection and the locking arm is recovered to the reverse direction of the bending, therefore the resilient force of the locking arm is prevented from deterirating with time passing by. 
     A third aspect of the present invention is to provide an inertial locking connector comprising: a first connector housing provided with a locking arm having a locking hole; and a second connector housing provided with an engaging projection, which engages with the locking hole, wherein the first connector housing is provided with an arm for inertial locking and the arm for inertial locking is provided with an abutting projection for abutting against a front end face of the second connector housing. 
     A pair of the arm for inertial locking is adjacently formed at both sides of the locking arm. 
     The arm for inertial locking and the locking arm are integrally formed with putting a slit therebetween. 
     According to the third aspect of the present invention, a large friction force does not applied to the engaging projection of the second connector housing upon the engagement of the connectors, thereby the wear of the engaging projection is prevented from occurring and the locking of the connectors is always securely implemented with high accuracy. 
     Further, since the projection of the arm for inertial locking abuts against the front end face of the second connector housing, when an operator presses both connector housings in the engaging direction thereof with a strong force and the arm for inertial locking is bent so as to engage both connector housings with each other by the inertia force, the locking arm advances powerfully toward the engaging projection situated more rear compared to the front end face of the second connector housing and the engaging projection engages with the locking hole at a stretch, therefore the incomplete engagement of the connectors never takes place, i.e. the connectors are securely engaged and locked with each other. 
     Furthermore, since the engaging projection of the second connector housing needs no construction for the inertial locking, a normal connector that is not for the inertial locking can be employed as the second connector, thereby decreasing the cost of parts. In addition, as a normal connector, a plurality of kinds of connector can be compatible with each other from the viewpoints of presence or absence of the waterproof rubber stopper and different total length of the connectors, thereby the degree of freedom for disposing position of the connectors and for connection form thereof is increased. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view illustrating a male connector of an inertial locking connector according to a first preferred embodiment of the present invention; 
     FIG. 2 is a perspective view illustrating a locking arm of the male connector; 
     FIG. 3 is a perspective view illustrating a female connector of the inertial locking connector according to the first preferred embodiment of the present invention; 
     FIGS. 4A,  4 B and  4 C are primary longitudinal sectional views illustrating states that the locking projection of the locking arm of a connector faces the front end face of an opposite connector housing, then abuts against the front end face and then, engages with the engaging projection; 
     FIG. 5 is a primary longitudinal sectional view illustrating an inertial locking connector according to a second preferred embodiment of the present invention; 
     FIG. 6 is a plan view illustrating a male connector of an inertial locking connector according to a third preferred embodiment of the present invention; 
     FIG. 7 is a front view illustrating the male connector of the inertial locking connector according to the third preferred embodiment of the present invention; 
     FIG. 8 is a longitudinal sectional view illustrating the male connector of the inertial locking connector according to the third preferred embodiment of the present invention; and 
     FIG. 9 is a longitudinal sectional view illustrating an example of a conventional inertial locking connector. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, the preferred embodiments of the present invention will be explained with reference to the attached drawings. FIGS. 1 to  3  illustrate an inertial locking connector according to a first preferred embodiment of the present invention, in which FIG. 1 shows a male connector, FIG. 2 shows a flexible locking arm of the male connector, and FIG. 3 shows a female connector. The inertial locking connector comprises the male and female connectors. 
     As shown in FIG. 1, the male connector  1  has a connector housing  4  consisting of a hood part  2  made of synthetic resin and an inner housing (terminal receiving part)  3 , and a locking arm  7  is integrally formed with an upper wall (wall part)  5  putting a holding part  6  therebetween. The front half of the locking arm  7  is situated inside the hood part  2 , while the rear half thereof including a pushing operation part  8  is exposed from an opening  9  of the hood part  2 . As shown in FIG. 2, the holding part  6  of the locking arm  7  is perpendicularly formed at both sides of the central portion in the length direction of the locking arm  7 , and an insertion space  12  for an engaging projection  11  of the female connector  10  shown in FIG. 3 is provided between a pair of the holding part  6 . The locking arm  7  is rotatable in the thickness direction of the plate of the locking arm  7  (i.e. locking and releasing directions) with using the holding part  6  as a fulcrum. 
     As shown in FIG. 2, a locking projection  13  for abutting and for locking is downwardly formed at the front end center of the locking arm  7 . As shown in FIG. 4A, a front end face (abutting face)  13   a  of the locking projection  13  continues downwardly from a perpendicular front end face  14   a  of the plate-shaped body  14  of the locking arm  7  and is inclined backward a little having a taper shape. The inclined angle θ 1  of the front end face  13   a  of the locking projection  13  from the perpendicularity is appropriately set up in response to a force needed for the engagement of both connectors  1  and  10 . 
     The inclined angle θ 1  of the front end face  13   a  is gradually changed so as to finely adjust the inertia force. That is, when a large inertia force is needed, the angle θ 1  is set to be near zero, on the other hand, when a small inertia force is needed, the angle θ 1  is set large. The inclined angle θ 2  of the locking projection  13  from the horizontality is equal to or less than 90°. In any case, the inertia force is set larger than the sum of a force needed for insertion of the male and female terminals, which has been mentioned in the conventional example, and a force needed for engaging the waterproof packing with the connector housing. 
     As shown in FIG. 4A, a rear end face  13   b  of the locking projection  13  is inclined backward by an angle equal to or more than that of the front end face  13   a  and as shown in FIG. 4C, functions as a locking face, which engages with the engaging projection  11  of the mating female connector  10 . A primary distinctive feature of the inertial locking connector according to the present preferred embodiment is that as shown in FIG. 4A the front end face  13   a  of the locking projection  13  is situated facing not the engaging projection  11  of the mating female connector  10  but a front end face  17   a  of a wall part (upper wall)  17 , which constitutes a connector engaging chamber  16  of a connector housing  15  (see FIG.  3 ), and abuts against the front end face  17   a  of the wall part  17  as shown in FIG.  4 B. 
     In FIG. 3, the female connector  10  is a known connector, to which no processing is added to make the connector an inertial locking connector. On the upper wall  17  of the female connector housing  15 , the engaging projection  11  is disposed a little backward compared to the front end face  17   a  of the upper wall  17 , and has an acute inclined guiding face  11   a  at the front and an approximately perpendicular abutting face  11   b  at the rear. An angle of the inclined guiding face  11   a  is smaller than the inclined angle θ 2  (see FIG. 4A) of the locking projection  13  of the locking arm  7  (see FIG.  1 ). 
     The front end face  17   a  of the upper wall  17  of the female connector housing  15  functions as an abutting part, which abuts against the locking projection  13 . The front end face  17   a  of the upper wall  17  is constituted by a perpendicular face similarly to each front end face of both sidewalls  18  and lower wall  19  of the connector housing  15 , and each front end face continues to an inner guiding tapered surface  20 . The inner housing  3  of the male connector  1  (see FIG. 1) is inserted along the guiding tapered surface  20 . 
     At both sides of the engaging projection  11 , the upper wall  17  is provided with a pair of guiding plate  21 , which advances to the outside of the locking arm  7  (see FIG.  1 ). Each sidewall  18  is provided with a guiding projection  23 , which advances into a side groove  22  of the hood part  2  (see FIG.  1 ). Male terminals (not shown in the figure) having a wire is received into the rear half of the connector housing  15  and a waterproof rubber stopper (not shown in the figure) is fit in a wire guiding part  24  at the rear. 
     In FIG. 1, female terminals (not shown in the figure) having a wire is received into the inner housing  3  of the male connector  1 . There are four terminal receiving chambers  25  in the present preferred embodiment. A waterproof packing (not shown in the figure) is fit to a base part of the inner housing  3 . 
     After each terminal is inserted into the male and female connector housing  4  and  15 , both connectors  1  and  10  are engaged with each other. Upon an initial stage of this engagement, as shown in FIG. 4B, the locking projection  13  of the locking arm  7  abuts against not the engaging projection but the front end face  17   a  of the mating connector housing  15 . Then, the operator pushes both connectors  1  and  10  in the engaging direction with a strong force, resulting in that the front end face  13   a  of the locking projection  13  slides on an upper end of the front end face  17   a  of the connector housing  15  while the locking arm  7  bends upward, then the locking projection  13  climbs over the engaging projection  11  at a stretch and engages with the rear side of the engaging projection  11 . 
     The locking arm  7  keeps the locked state as the locking arm  7  is bent upward. As the locking arm  7  is bent upward, the rear end face (locking face)  13   b  of the locking projection  13  stands about perpendicularly and abuts against the perpendicular rear end face (engaging face)  11   b  at the rear of the locking projection  11 , thereby a strong locking force is attained. At the initial state shown in FIG. 4A, an inclined angle of the rear end face  13   b  of the locking projection  13  is set equal to or smaller than 90° similarly to the front end face  13   a . In the connector engaged state shown in FIG. 4C, the locking arm  7  resiliently energizes the upper wall  17  of the connector housing  15  and the locking projection  11  downward, therefore the locking arm  7  is prevented from coming off abruptly, the locking arm is firmly engaged with the engaging projection, and a frictional wear due to the vibration and the like during the running of the vehicle never takes place. 
     Differently from the prior art, according to the present preferred embodiment, the inertia force is obtained not by abutting the projections  11  and  13  against each other but at the preceding stage when the locking projection  13  abuts against the front end face  17   a  of the connector housing  15 , thereby the inertia force makes the locking projection  13  climb over the engaging projection  11  at a stretch. Consequently, there is no possibility that both connectors  1  and  10  stop staying in half engaged condition (i.e. incomplete engaged condition) in a state that the locking projection  13  climbs on the engaging projection  11 . 
     As shown in FIG. 4A, the effect described above is further promoted by a construction that a small distance L between the front end face  17   a  of the connector housing  15  and the engaging projection  11  for the locking projection  13  to slide is provided. That is, as shown in FIG. 4B, after the locking projection  13  abuts against the front end face  17   a  of the connector housing  15 , the locking projection  13  is accelerated until it climbs over the engaging projection  11 , thereby the locking projection  13  can more securely climb over the engaging projection  11 . 
     As shown in FIG. 4B, the front end face  13   a  of the locking projection  13  strongly abuts against and slides on the front end face  17   a  of the connector housing  15 , therefore the locking projection  13  does not strongly press the engaging projection, thereby the deformation and wear of the engaging projection  11  are prevented from occurring and the locking force does not deteriorate even when the connectors  1  and  10  are repeatedly engaged with and separated from each other. 
     As shown in FIG. 3, the front end face  17   a  of the connector housing  15  extends far longer than the width of the locking projection  13  (see FIG.  2 ), therefore the front end face  17   a  has a high stiffness, thereby the front end face  17   a  is hardly deformed and the wear thereof is very little even when the connectors  1  and  10  are repeatedly engaged with and separated from each other. The locking projection  13  bends together with the locking arm  7 , thereby the wear and deformation thereof hardly take place. Consequently, the inertia force does not deteriorate even when the connectors  1  and  10  are repeatedly engaged with and separated from each other. 
     As shown in FIGS. 2 and 4, at an upper side of the locking projection  13 , there may be provided a notched hole  27  in a main portion  14  of the locking arm  7  so that the locking projection  13  can slightly bend as it can rotate according to a direction, to which it is pressed. The amount of the bend is set so as not to damage the inertia force. Thereby, the deformation and wear of the locking projection  13  are also securely prevented from occurring. 
     As shown by a chain line in FIG. 4A, the front end face  13   a  of the locking projection  13  may be formed perpendicular to the connector engaging direction and in this case, the front end face  13   a  of the locking projection  13  abuts against the whole surface of the front end face  17   a  in a range of about the plate thickness T of the upper wall  17  of the connector housing  15 , thereby a very large inertia force can be produced when the locking arm  7  bends. The magnitude of the inertia force is set suitably according to the type of the connector, and the locking projection having such a perpendicular front end face can be employed when the number of the terminals is very large and the connector having a waterproof packing is large. 
     In FIG. 4C, in order to delete the bend of the locking arm  7 , the locking arm  7  may be provided with a hole (by enlarging the size of the notched hole  27 ) for allowing the engaging projection  11  to advance and the connector housing  15  may be provided with a hole (not shown in the figure) for allowing the locking projection  13  to advance, thereby the resilient force of the locking arm  7  is prevented from deterirating with time passing by. 
     FIG. 5 is a primary longitudinal sectional view illustrating an inertial locking connector according to a second preferred embodiment of the present invention. As shown in FIG. 5, instead of providing a locking projection on a plate-shaped locking arm  32  of one connector housing  31 , a locking hole  33  is provided at the front end side, while an engaging projection  36  engaging with the locking hole  33  is provided on an upper wall  35  of an opposite connector housing  34  so that a front end face  32   a  of the locking arm  32  abuts against an inclined front end face  36   a  of the engaging projection  36  so as to produce the inertia force, then the locking hole  33  engages with the engaging projection  36  at the same time when both connectors  37  and  38  engage with each other. 
     In this second preferred embodiment, if the locking arm  32  has a perpendicular (to the connector engaging direction) front end face  32   a , a known connector can be employed as the one connector  37 . As for the opposite connector  38 , the inclined angle of the engaging projection  36  has to be set an angle near to 90° as the inertial locking connector as shown in FIG.  5 . An inclined angle θ 3  of a front end face  36   a  of the engaging projection  36  is set an angle equal to or smaller than 90° according to the inertia force. The angle θ 3  is an inclined angle of the front end face  36   a  with regard to a wall surface (horizontal plane) of the connector housing  34 . 
     In the preferred embodiment shown in FIG. 5, not a locking projection but the main portion of the locking arm  32  climbs on the engaging projection, therefore the sliding property thereof with regard to the engaging projection is good, the locking hole  33  can easily engages with the engaging projection  36  with the momentum of the climbing on thereof, thereby an incomplete engagement of the connectors hardly takes place. 
     In the preferred embodiment shown in FIG. 1, a connector without the hood part  2  may be employed as the male connector  1 . In this case, the inner housing  3  is used as a rectangular block-shaped connector housing and a waterproof packing outside of the housing is not used. 
     Instead of the female connector  38  shown in FIG. 5, a wall portion ( 35 ) constituting a connector engaging chamber of the female connector housing ( 35 ) may be notched by a pair of slits (not shown in the figure) so as to form a locking arm ( 32 ) between both slits, the locking arm may be provided with a locking hole ( 33 ) similarly to FIG. 5, an outer wall of the male connector housing may be provided with an engaging projection ( 36 ) engaging with the locking hole ( 33 ), thereby a front end face of the locking arm ( 32 ) abuts against a front end face of the engaging projection ( 36 ) to obtain the inertia force. 
     Further, the front end face  13   a  of the locking projection  13  of the locking arm  7  of the male connector  1  in FIG. 1 may directly slide on the front end face  11   a  of the engaging projection  11  of the female connector  10 , thereby the connector can be used not as an inertial locking connector but as a normal connector. Furthermore, the shape of the locking arm  7  is not limited to the shape that the central part of the locking arm  7  in the length direction is held by the holding part  6  (see FIG.  2 ), and the shape may be a shape that the rear end of the locking arm  7  is held as a cantilever. 
     FIGS. 6-8 illustrate a male connector  65  of an inertial locking connector according to a third preferred embodiment of the present invention. 
     Besides the locking arm  66  for locking the connectors, the inertial locking connector  65  according to the third preferred embodiment is also provided with an arm  67  for inertial locking, with a front end which has an abutting projection  68  which is integrally formed so that a front end face  68   a  of the abutting projection  68  abuts against a front end face  17   a  of a connector housing of the mating female connector  15 , thereby the inertia force can be obtained. Both male and female connectors constitute the inertial locking connector. 
     As shown in FIGS. 6 and 7, the locking arm  66  is disposed inside the hood part  69  made of synthetic resin and a pair of the arms  67  for inertial locking is provided adjacently to both sides of the locking arm  66 . Each arm  67  is formed narrow (about half of the width of a plate part  71  at both sides of a hollow part  70  of the locking arm  66 ) compared to the locking arm  66 , the front end  68   a  of the arm  67  is situated a little backward compared to a front end  66   a  of the locking arm  66 , each arm  67  and the locking arm  66  are situated closely with each other with putting a slit  72  therebetween, a base part of each arm  67  and that of the locking arm  66  are integrated with each other as a common arm base  73 , and a pushing operation part  74  is provided at the rear end side of the arm base  73 . 
     The locking arm  66  and a pair of the arm  67  for inertial locking constitute an arm structural unit  75 , thereby the structure is simplified and compacted compared to a case, in which the locking arm and the arm for inertial locking are separately formed, and molding workability with using resin is improved. 
     As shown in FIG. 8, the locking arm  66  and the arm  67  are situated on the same horizontal plane, a holding part  76  is formed a little forward at both sides of the arm base  73 , and the holding part  67  connects the arm base  73  to an upper wall  78  of an inner housing  77 . By pressing the pushing operation part  74  downward, both arms  66  and  67 , i.e. the arm structural unit  75  rotates upward with the holding part  76  as a fulcrum. (This is an operation when the connectors are to be separated from each other.) 
     The locking arm  66  has a connecting wall  79  at the front end side thereof and the rectangle plate part  71  (see FIG. 6) at both sides, right and left, and the hollow part  70  surrounded by the connecting wall  79  and both plate parts  71  functions as a locking hole  70  for engaging with the engaging projection ( 11  in FIG. 3) of the mating female connector. At both sides of the connecting wall  79 , the abutting projection  68  of a pair of the arm  71 , right and left, is situated protrudingly more downward compared to the connecting wall  79 . The rear end face  68   b  (see FIG. 8) of the abutting projection  68  is inclined a little and situated at the lower side of about the side of a rear end  79   a  of the connecting wall  79 . The front end face  68   a  of the abutting projection  68 , i.e. an abutting face for abutting against the front end face ( 17   a ) of the mating female connector housing ( 15  in FIG. 3) is perpendicularly formed with an angle 90° in the third preferred embodiment. 
     A waterproof packing  80  is situated under the abutting projection  68 , which is fit to the base side of the inner housing  77 . The waterproof packing  80  enlarges a force needed for engaging with the mating female connector ( 10  in FIG.  3 ), also causing a necessity of the inertial locking. Female terminals  81  (see FIG. 8) are inserted into the inner housing  77 , each female terminal  81  has a solderless contact with a wire  82 , on which a waterproof rubber stopper  83  is fit. The female terminals  81  are arranged in parallel and as shown in FIG. 7 a front wall  84  of the inner housing  77  is provided with an insertion hole  85  for inserting the male terminal of the mating connector. The hood part  69  and the inner housing  77  integrally constitute a connector housing  86  (see FIG. 8) made of synthetic resin. 
     When the male and female connectors  65  and ( 10 ) are engaged with each other, the front end face ( 17   a ) of the connecter housing ( 15 ) of the mating female connector ( 10 ) abuts against the projection  68  of a pair of the arms  67  for inertial locking. At almost the same time, the engaging projection ( 11 ) of the female connector ( 10 ) slips into the bottom of the front end  66   a  of the locking arm  66  and may bend the locking arm  66  upward a little. Even in such a case, since the locking arm  66  and the arms  67  for inertial locking at right and left are separated by the slit  72 , the bend of the locking arm  66  is not transmitted to the arms  67 , thereby the arms  67  for inertial locking does not bend and keeps situating horizontally and can firmly hold the front end face ( 17   a ) of the mating connector housing ( 15 ). 
     When an abutting force between the projection  68  of the arm  67  for inertial locking and the front end face ( 17   a ) of the female connector housing ( 15 ) exceeds a sum of the insertion force worked between the male and female terminals and the insertion force for the waterproof packing  80  to be inserted into the female connector housing ( 15 ), a pair of the arms  67  bends upward, thereby the male and female connectors,  65  and ( 10 ), respectively, engage at a stretch with each other. At the same time, the engaging projection ( 11 ) engages with the locking hole  70  of the locking arm  66 , thereby both connectors  65  and ( 10 ) are locked (inertially locked) without coming off. 
     In the third preferred embodiment described above, the front end face  68   a  of the projection  68  of the arm  67  for inertial locking may be formed inclined by a suitable angle equal to or smaller than 90° according to the magnitude of the inertia force, similarly to the locking projection  13  of the locking arm  7  (see FIG. 1) of the first preferred embodiment. 
     The aforementioned preferred embodiments are described to aid in understanding the present invention and variations may be made by one skilled in the art without departing from the spirit and scope of the present invention.