Abstract:
A female terminal fitting ( 12 ) has tube ( 19 ) for receiving a male terminal fitting ( 10 ). A main spring ( 27 ) is cantilevered forwardly from the tube ( 19 ) and an auxiliary spring ( 30 ) is cantilevered forwardly at the outer side of the main spring piece ( 27 ). Stoppers ( 32 ) bulge out from the opposite sides of the auxiliary spring ( 30 ) for preventing the auxiliary spring ( 30 ) from being displaced up when the free end of the auxiliary spring ( 30 ) is thrust up from the outer side. Receiving portions ( 33 ) are left in the tube ( 19 ) during the forming of the auxiliary spring ( 30 ) and contact the stoppers ( 32 ). Thus, even if an external matter strikes against the auxiliary spring ( 30 ), the auxiliary spring ( 30 ) will not deform excessively in thrust-up direction.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a terminal fitting and a connector using such a terminal fitting. 
   2. Description of the Related Art 
   Japanese Unexamined Patent Publication No. H11-224709 discloses a terminal fitting with a tubular portion for receiving a mating terminal. A resiliently deformable spring piece is provided in the tubular portion and an auxiliary spring is a cantilevered forward at the outer side of the spring piece. The mating terminal is inserted into the tubular portion and deforms the spring piece. Thus, the deformed spring piece is urged resiliently against the mating terminal fitting to establish electrical connection. Additionally, the auxiliary spring contacts the spring piece from the outer side to reinforce the resilient force of the spring piece. 
   However, the auxiliary spring piece is exposed at the side surface of the tubular portion in the above construction. As a result, external matter can strike and deform the auxiliary spring. 
   The invention was developed in view of the above problem and an object thereof is to provide a terminal fitting that prevents a spring portion from being deformed excessively and a connector using such a terminal fitting. 
   SUMMARY OF THE INVENTION 
   The invention relates to a terminal fitting, comprising a tube for receiving a mating terminal. A spring is exposed at a side surface of the tube. The spring includes at least one stopper, and the tube includes at least one receiving portion disposed to contact the stopper for preventing displacement of the spring inwardly when the spring is forced in from an outer side. 
   The spring preferably has a free front end. 
   The spring preferably has a main spring that is cantilevered forward in the tube and an auxiliary spring that is cantilevered forward at the outer side of the main spring. 
   The auxiliary spring preferably is formed by making a cut in a surface of the tube that faces the main spring and bending a cut portion. 
   The stopper preferably bulges out from at least one of the opposite sides of the auxiliary spring with respect to the width direction. A receiving portion is formed at an opening edge of the stopper that is left in the tube by forming the auxiliary spring through cutting and bending. 
   The stopper preferably bulges out from the opposite sides of the auxiliary spring with respect to the width direction. The receiving portion preferably is an opening edge left in the tube by forming the auxiliary spring. Accordingly, excessive deformation of the auxiliary spring in a thrust-up direction can be prevented even when an external matter strikes against the spring. Further, separate processing steps are not required to form the receiving portion. 
   The invention also relates to a connector with the above-described terminal fitting. The terminal fitting has a tube for receiving a mating terminal fitting and a barrel for engaging a wire. The tube and the barrel define heights measured from a bottom surface of the terminal fitting. The height of the barrel exceeds the height of the tube. The connector also has a housing with a cavity for accommodating the terminal fitting. The cavity has a step at a boundary between a portion that accommodates the tube and a portion that accommodates the barrel. The height of the accommodating portion for the barrel exceeds the height of the accommodating portion for the tube. 
   A demand exists for smaller connectors, and the miniaturization of connectors results in smaller terminal fittings. The height of the barrel to be connected with a wire may exceed the height of the tube to be connected with the mating terminal fitting due to required dimensions of the wire. Outer surfaces of a female housing may be taller at a part corresponding to the barrel and shorter at a part corresponding to the tube in view of the height differences in the terminal fitting. The part of the female housing corresponding to the relatively short tube is fit into a receptacle of the male housing. Thus, the height of the connector can be reduced as compared to a case where the outer surfaces of the female housing conform to the height of the barrel. 
   The terminal fitting can collide with the step as the terminal fitting is inserted into the cavity. However, the terminal fitting prevents the spring from deforming excessively even if the spring and the step collide. Moreover, the height of the connector can be shortened. 
   The spring of the terminal fitting preferably is a main spring. The terminal fitting may further have an auxiliary spring cantilevered forward at the outer side of the main spring. A reinforcement preferably is provided for reinforcing the main spring and/or auxiliary spring. The reinforcement preferably is at the base end of the main spring and/or auxiliary spring and enhances the rigidity of the main spring and the auxiliary spring. Thus, a high contact pressure with the mating terminal can be obtained. 
   The reinforcement preferably comprises a bulge formed by embossing a flat surface of the main spring and/or auxiliary spring. 
   The spring preferably is cantilevered forward from the rear of the tube. The spring preferably has a first area extending substantially forward from the rear end, a second area extending from the front end of the first area, and a third area extending from the front end of the second area to the front end of the spring. The spring contacts the tube in the first area, is slightly distanced from the tube in the second area, and substantially contacts the tube at a boundary between the second and third areas. 
   These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a section of a connector according to the invention. 
       FIG. 2  is a side view of a female terminal fitting of the connector. 
       FIG. 3  is a plan view of the female terminal fitting. 
       FIG. 4  is a bottom view of the female terminal fitting. 
       FIG. 5  is a development of the female terminal fitting. 
       FIG. 6  is a side view partly in section of the female terminal fitting. 
       FIG. 7  is an enlarged side view in section of a tube of the female terminal fitting. 
       FIG. 8  is an enlarged bottom view of the tube. 
       FIG. 9  is a section along  9 — 9  of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A connector assembly according to the invention has male terminal fittings  10  disposed at two stages in a male housing  11  and female terminal fittings  12  disposed at two stages in a female housing  13 , as shown in  FIGS. 1 to 9 . The two housings  11 ,  13  are connectable with and separable from each other. In the following description, connecting directions of the housings  11 ,  13  are referred to as the forward directions. Reference is made to  FIG. 1  concerning the vertical direction of the housing, but reference is made to  FIGS. 2 and 7  for the vertical direction of the female terminal fitting  12 . 
   As shown in  FIG. 1 , the male housing  11  is made e.g. of a synthetic resin and includes a receptacle  14  with an open front end. The male terminal fittings  10  are mounted through the rear wall of the receptacle  14  and project into the receptacle  14 . 
   The female housing  13  is made e.g. of a synthetic resin and has cavities  15  for accommodating the female terminal fittings  12 . Insertion openings  16  for insertion of the male terminal fittings  10  are formed in the front wall of the female housing  13  and conform to the respective cavities  15 . 
   The female terminal fitting  12  is inserted into each cavity  15  from behind while being turned upside down, and is locked by a lock  17  formed in the cavity  15  and by a retainer  18  inserted from below the female housing  13 . 
   Each female terminal fitting  12  is narrow and long along forward and backward directions, and is formed by bending, folding and/or embossing a conductive metal plate that has been stamped or cut into a specified shape (see  FIG. 5 ). A substantially rectangular tube  19  is formed at the front of the female terminal fitting  12  and is configured for receiving the male terminal fitting  10 . A barrel  20  is formed at the rear of the female terminal fitting  12 . 
   Crimping pieces project from opposite lateral edges of a bottom plate of the female terminal fitting  12  along the barrel  20 . The crimping pieces at the front of the barrel  20  define a wire barrel  20 A and are configured to be crimped, bent or folded into connection with a core of the wire  21 . The crimping pieces at the rear of the barrel  20  define an insulation barrel  20 B and are configured to be crimped, bent or folded into connection with an insulation coating of the wire  21 . The height of the wire barrel  20 A is substantially equal to the height of the tube  19 , but is less than the height of the insulation barrel  20 B. Thus, a sloped step  22  is formed at the bottom surface of the cavity  15  at a boundary between an accommodating portion  37 A for accommodating the tube  19  and the wire barrel  20 A and an accommodating portion  37 B for accommodating the insulation barrel  20 B. On the other hand, the surface of the cavity  15  opposed to the step  22  defines a substantially uniform height along the front and rear accommodating portions  37 A,  37 B. 
   The outer surface of the female housing  13  is raised at a part corresponding to the insulation barrels  20 B, but is lowered at a part corresponding to the tubes  19  in view of the height differences of the female terminal fittings  12  (see  FIG. 1 ). Thus, a part of the female housing  13  corresponding to the relatively shorter tubes  19  is fit into the receptacle  14  of the male housing  11 . Therefore, the height of the connector is short as compared to a case where the outer surface of the female housing  13  conforms to the height of the insulation barrels  20 B. 
   The tube  19  has a base wall  23  that is narrow and long along forward and backward directions, as shown in  FIGS. 2 to 4 . The base wall  23  is continuous and flush with the base plate of the barrel  20 . Side walls  24  project up from opposite lateral edges of the base wall  24 , and a ceiling wall  25  extends from the upper end of one side wall  24  to face the base wall  23 . 
   A coupling  26  extends down from the rear end of the ceiling wall  25  along one side wall  24 , as shown in  FIGS. 5 and 6 , and a substantially plate-shaped main spring  27  extends along the bottom wall  23  from the bottom end of the coupling  26 . 
   The main spring  27  cantilevers forward from the rear end of the tube  19 , as shown in  FIGS. 6 and 7 , and has a first area P that extends forward from the rear end for about one fourth the length of the main spring  27 . A second area Q extends from the front end of the first area P and is slightly shorter than the first area P along forward and backward directions. A third area R extends from the front end of the second area Q to the front end of the main spring  27 . The main spring  27  contacts the bottom wall  23  in the first area P, is spaced slightly from the bottom wall  23  in the second area Q, and contacts the bottom wall  23  at a boundary between the second and third areas Q and R. The third area R, the main spring  27  extends obliquely up to the front, but a front end of the third area is bent at a large obtuse angle to extend obliquely down to a tip. A contact  28  is embossed and bulges out at the obtuse angle bend. The main spring  27  in the third area R gradually narrows towards the front end. 
   A substantially rectangular pressure receiving portion  29  is embossed down in an area of the ceiling wall  25  above the contact  28  of the main spring  27 , as shown in  FIGS. 3 and 6 , to ensure a contact pressure between the contact  28  and the male terminal fitting  10 . A distance between the pressure receiving portion  29  and the contact  28  in the undeformed state is less than the thickness of the mating terminal fitting  10 . A locking hole  35  is formed behind the pressure receiving portion  29  and engages the lock  17  to retain the female terminal fitting  12 . 
   An intermediate portion of the base wall  23  is cut and bent to form a substantially rectangular auxiliary spring  30  that cantilevers obliquely up and in to the front (see  FIG. 5 ). The auxiliary spring  30  is exposed at the bottom of the tube  19 . Additionally, the auxiliary spring piece  30  extends along the lower surface of the third area R of the main spring  27  substantially at the same angle of inclination as the main spring  27  and over a distance of more than about half of the extension of the third area R. The front end of the auxiliary spring  30  is slightly obliquely behind the contact  28  of the main spring  27 . 
   The main spring  27  and the auxiliary spring  30  are spaced from each other when they are both in their natural states and not resiliently deformed. However, the lower surface of the main spring  27  contacts the front end of the auxiliary spring  30  from above when the main spring piece  27  is deformed resiliently down and out (see  FIGS. 2 and 8 ). 
   A bulge  31  is embossed up and in at a base end of the auxiliary spring  30  and a portion adjacent thereto. The bulge  31  enhances the rigidity of the auxiliary spring  30  (see  FIGS. 7 and 9 ). The bulge  31  is substantially rounded to define the shape of a water drop and is distanced from the main spring  27  when the main spring  27  and the auxiliary spring  30  are undeformed. 
   Two stoppers  32  project out laterally in a common plane from front portions of the left and right edges of the auxiliary spring  30 . Left and right receiving portions  33  are formed at the edges of the opening that is left in the base wall  23  by forming the auxiliary spring  30  and the stoppers  32 . The receiving portions  33  are at boundaries between the bottom wall  23  and the left and right walls  24  at positions corresponding to the stoppers  32 . The stoppers  32  are below the receiving portions  33  when the auxiliary spring  30  is not deformed, but contact the receiving portions  33  from below if thrust up by external matter. This contact prevents the auxiliary spring  30  from being excessively deformed up towards the main spring  27 . The stoppers  32  do not bulge out from the side walls  24  of the tube  19 , as shown in  FIG. 8 . 
   As shown in  FIGS. 7 and 8 , a substantially rectangular escaping hole  34  is formed in a part of the base wall  23  before the auxiliary spring  30  and below the front end of the main spring piece  27 . The escaping hole  34  avoids interference with the front end of the main spring  27  when the main spring  27  is deformed resiliently down and out. An excessive deformation preventing portion  36  is defined in area of the base wall  23  substantially corresponding to the contact  28  of the main spring  27  for contacting the lower surface of the main spring  27  from below or outside to prevent excessive deformation. 
   The female terminal fitting  12  is inserted into the cavity  15  of the female housing  13 . The lock  17  then engages the locking hole  35  to retain the female terminal fitting  12 . At this time, the tube  19  and the wire barrel  20 A of the female terminal fitting  12  are accommodated in the cavity  15  before the step  22 , and the insulation barrel  20 B is accommodated behind the step  22 . 
   The retainer  18  is mounted from below after the female terminal fittings  12  are accommodated in the respective cavities  15 . Thus, the retainer  18  engages the rear ends of the tubes  19  to lock the female terminal fittings  12 . 
   The female housing  13  then is fit into the receptacle  14  of the male housing  11  from the front. As the connection progresses, the male terminal fittings  10  enter the tubes  19  through the insertion openings  16  of the female housing  13 . The male terminal fittings  10  then engage the contacts  28  of the main springs  27  and deform the main springs  27  down. As a result, the deformed main springs  27  contact the front ends of the auxiliary springs  30  from above and deform the auxiliary springs  30  down and out. Accordingly, resilient forces of the main springs  27  and the auxiliary springs  30  act on the male terminal fittings  10  to squeeze the male terminal fittings  10  between the pressure receiving portions  29  of the ceiling walls  25  of the tubes  19  and the contacts  28  of the main springs  27  to establish electrical connections. 
   The bulge  31  is formed at the base end of each auxiliary spring  30  by embossing or by providing a thicker wall. Thus, the rigidity of the auxiliary spring  30  is enhanced. In this way, the main spring  27  is reinforced to increase the resilient force on the male terminal fitting  10 . Therefore, a high contact pressure is ensured for each male terminal fitting  10 . 
   The bulge  31  is formed merely by embossing the base end of the auxiliary spring  30 . Thus, the auxiliary spring  30  is reinforced easily. 
   The two housings  11 ,  13  are held connected by an unillustrated known locking mechanism. 
   According to this embodiment, the outer surfaces of the female housing  13  are cross-sectionally larger at a part corresponding to the insulation barrels  20 B, but are cross-sectionally smaller at a part corresponding to the tubes  19  in view of the height differences in the individual female terminal fittings  12 . Thus, the part of the female housing  13  corresponding to the tubes  19  is fit in the receptacle  14  of the male housing  11 , and the height of the connector is reduced as compared to a case where outer surfaces of the female housing  13  conform with the height of the insulation barrels  20 B. 
   The steps  22  are necessary at the boundaries between the accommodating portions  37 A for the tubes  19  and the wire barrels  20 A and the accommodating portions  37 B for the insulation barrels  20 B. Thus, the bottom wall  23  contacts the step  22  if an operator inadvertently tries to insert the female terminal fittings in a vertically inverted posture. 
   The auxiliary spring  30  is exposed at the bottom wall  23 . Thus, there is a possibility that the auxiliary spring  30  will contact the step  22  and be deformed resiliently in a thrust-up direction. However, the auxiliary spring  30  has the stoppers  32  that contact the receiving portions  33  of the tube  19  from below. Thus, the auxiliary spring  30  will not deform excessively. 
   The female terminal fittings  12  of this embodiment are effective in reducing the height of the female housing  13 . 
   The receiving portions  33  are formed by parts of the opening edge left by cutting and bending the tube  19  to form the auxiliary spring piece  30 . Thus, no new processing is necessary to form the receiving portions  33 . 
   The invention is not limited to the above described embodiment. For example, the following embodiments also are embraced by the invention as defined by the claims. Various other changes can be made without departing from the scope of the invention as defined by the claims. 
   The stoppers  32  are on the auxiliary spring  30  in the foregoing embodiment. However, they may be on the main spring  27  and may contact the receiving portions  33  of the tube  19 . In this case, the auxiliary spring  30  may be omitted. 
   The front end of the auxiliary spring  30  projects sideways along width direction to form the stoppers  32  in the foregoing embodiment. However, the tube  19  may have stoppers  32  instead. 
   The reinforcing portion is formed by embossing the flat surface of the auxiliary spring  30  to make a round projection in the foregoing embodiment. However, the reinforcing portion may be a long narrow rib. 
   Although the reinforcing portion is formed by embossing in the foregoing embodiment, it may be formed by cutting and bending. 
   The reinforcing portion may contact the lower surface of the main spring  27  when the springs  27  and  30  are not deformed. 
   Although the bulge  31  bulges up and in the foregoing embodiment, the bulge  31  may bulge down and out.