Patent Publication Number: US-8109791-B2

Title: Shield connector

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a shield connector to be used when electronic instruments mounted, for example, on a motor vehicle are electrically connected with each other. 
     (2) Description of the Related Art 
     Various electronic instruments are mounted on a motor vehicle as a mobile unit. Therefore, the motor vehicle is provided with a wiring harness for transmitting electric power and signals to the electronic instruments. The wiring harness includes a plurality of electric wires and connectors. 
     The electric wire is so-called a coated electric wire which includes an electrically conductive core wire and a coating, which is made of electrically insulating synthetic resin and coats the core wire. So far, various shield connectors  100  (shown in  FIG. 8  as an example) have been used as the connector described above. 
     The shield connector  100  shown in  FIG. 8  is placed on and fixed to a printed circuit board. The shield connector  100  includes an inner housing  101  made of electrically insulating synthetic resin, a terminal fitting  102  attached to the inner housing  101 , an inner shield shell  103  made of metal, an outer housing  104  made of electrically insulating synthetic resin, and an outer shield shell  105  made of metal. 
     The inner housing  101  is formed in a shape of a square tube having one closed end. The terminal fitting  102  is made of metal and formed in a bar-shape. One end part of the terminal fitting  102  is received in the inner housing  101 , while another end part thereof is bent at right angles from the one end part and arranged outside the inner housing  101 . 
     The inner shield shell  103  is formed by bending a sheet metal. The inner shield shell  103  receives the inner housing  102  therein and integrally includes: a shell body  106 , an inner surface of which is closely placed on an outer surface of the inner housing  102 ; and a fixing piece  107  which rises up from the shell body  106  and fixed to a conductor pattern of a printed circuit board. 
     The outer housing  104  is formed in a square tube-shape receiving the inner housing  101  and the inner shield shell  103  therein. The outer shield shell  105  is formed by bending a sheet metal. The outer shield shell  105  receives the outer housing  104  therein and integrally includes: a shell body  108 , an inner surface of which is closely placed on an outer surface of the outer housing  104 ; and a resilient contacting piece  109  which rises up from the shell body  108  inwardly and resiliently comes in contact with the inner shield shell  103 . 
     The shield connector  100  is coupled with a mating connector and guides an electric noise to be leaked to the outside from the terminal fitting  102  and an electric noise to enter the terminal fitting  102  from the outside to a ground circuit by way of the shield shell  103 , the outer housing  104 , the fixing piece  107  of the shield shell  103 , and the conductor pattern of the printed circuit board. 
     Since the conventional shield connector  100  shown in  FIG. 8  includes the inner housing  101  and the outer housing  104 , which are covered by the shield shell  103  and the shield shell  105 , respectively, therefore as shown in  FIG. 9 , a gap takes place between the housings  101  and  104 , resulting in that a shielding characteristic is hardly secured with the shield shells  103  and  105 . That is, the electric noise is hardly prevented from entering the terminal fitting  102  and the electric noise is hardly prevented from leaking from the terminal fitting  102 . 
     Moreover, the outer shield shell  105  is provided with the resilient contacting piece  109  which comes in contact with the inner shield shell  103  and electrically connects the shield shells  103  and  105  to each other. Therefore, the housings  101  and  104  vibrate relatively to each other by vibration of a traveling motor vehicle, resulting in that a contact between the resilient contacting piece  109  and the inner shield shell  103  becomes unstable. 
     SUMMARY OF THE INVENTION 
     It is therefore an objective of the present invention to solve the above problems and to provide a shield connector which can securely perform an electric shield. 
     In order to attain the above objective, the present invention is to provide a shield connector including: 
     a plurality of terminal fittings; 
     a housing holding the plurality of the terminal fittings; 
     an electrically conductive inner shield shell receiving the housing; and 
     an electrically conductive outer shield shell receiving the inner shield shell, 
     wherein the outer shield shell includes: a square tube-shaped shell body; and surface-fixing parts, each of which is formed projecting from a peripheral wall of the shell body toward the inside of the shell body and has a parallel wall, which is formed parallel to the peripheral wall and is placed closely on (i.e. closely comes in contact with) an outer surface of the inner shield shell. 
     With the construction described above, since the outer shield shell is provided with surface-fixing parts, each of which is formed projecting from a peripheral wall of the shell body toward the inside of the shell body and placed closely on an outer surface of the inner shield shell, therefore the outer shield shell can be fixed without using an outer housing. 
     Since the outer shield shell can be fixed without using an outer housing, therefore a gap between the inner shield shell and the outer shield shell can be prevented from occurring. Therefore, the terminal fittings existing in the housing can be securely electrically shielded from the outside. Further, since the outer shield shell is provided with the surface-fixing parts, therefore when the shield connector is mounted on a motor vehicle, even if vibration during travelling of the motor vehicle takes place, the surface-fixing parts come in close contact with the outer surfaces of the inner shield shell, so that the inner shield shell and the outer shield shell can be securely electrically connected to each other. 
     The shield connector further includes fixing parts each fixing the surface-fixing part of the outer shield shell and a portion of the inner shield shell, which portion is placed on (i.e. closely comes in contact with) the surface-fixing part of the outer shield shell, to each other. 
     With the construction described above, since the shield connector further includes the fixing parts, the surface-fixing part of the outer shield shell and the inner shield shell can be securely fixed to each other, that is, the outer shield shell and the inner shield shell can be securely fixed to each other. Therefore, when the shield connector is mounted on a motor vehicle, even if vibration during travelling of the motor vehicle takes place, the surface-fixing part comes in close contact with an outer surface of the inner shield shell, so that the inner shield shell and the outer shield shell can be further securely electrically connected to each other. 
     The shell body is placed on a printed wiring board so that the outer shield shell is fixed to the printed wiring board, wherein the shell body is provided with a notch formed ranging from an end in a longitudinal direction of a peripheral wall of the shell body to a center of the peripheral wall, said peripheral wall being placed on the printed wiring board, wherein facing surfaces of inner edges of the notch, which face each other in a width direction of the shell body having a distance therebetween, extend along a longitudinal direction of the shell body, wherein the inner shield shell includes a pair of fixing pieces to be fixed to the printed wiring board and the fixing pieces are placed closely on (i.e. closely come in contact with) the respective facing surfaces. 
     With the construction described above, since the fixing pieces of the inner shield shell are placed closely on the respective facing surfaces of the outer shield shell, therefore the fixing pieces can be prevented from being displaced after being fixed to the printed wiring board, so that electrical connection between the shield connector and the printed wiring board can be prevented from being unstable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a shield connector according to a preferred embodiment of the present invention; 
         FIG. 2  is a perspective view viewed from the back of the shield connector shown in  FIG. 1 ; 
         FIG. 3  is a perspective view viewed from the bottom of the shield connector shown in  FIG. 1 ; 
         FIG. 4  is a perspective view of shield shells of the shield connector shown in  FIG. 1 ; 
         FIG. 5  is a cross sectional view taken along V-V line in  FIG. 1 ; 
         FIG. 6  is a cross sectional view taken along VI-VI line in  FIG. 1 ; 
         FIG. 7  is a cross sectional view taken along VII-VII line in  FIG. 1 ; 
         FIG. 8  is a perspective view of a conventional shield connector; and 
         FIG. 9  is a plan view illustrating a plane of the shield connector shown in  FIG. 8 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, a shield connector according to a preferred embodiment of the present invention will be explained with reference to  FIGS. 1-7 . The shield connector  1  is attached to a printed wiring board (not shown in the figure) and fitted to a mating connector (not shown in the figure) of a wiring harness, thereby being mounted on a motor vehicle. The shield connector  1  supplies signals and electric power to various electronic instruments mounted on the motor vehicle. 
     The printed wiring board, to which the shield connector  1  is attached, includes a board made of electrically insulating synthetic resin and a circuit pattern (not shown in the figure) formed on the board. The board is formed in a flat plate-shape. Various electronic instruments (not shown in the figure) are mounted on the board. The circuit pattern is made of metal such as copper, formed in a foil-shape (film-shape), and stuck onto (printed on) a surface of the board. The circuit pattern electrically connects the electronic instruments mounted on the board to each other according to a predetermined pattern. The circuit pattern is electrically connected to a ground circuit of the motor vehicle. 
     As shown in  FIGS. 1-3  and  5 , the shield connector  1  includes a housing  2 , a set  3  of terminal fittings, an inner shield shell  4 , an outer shield shell  5 , and a fixing part  6 . 
     The housing  2  is made of electrically insulating synthetic resin and as shown in  FIGS. 5 and 6 , one end of the housing  2  is closed by a wall  7   a  and formed in a square tube-shape by peripheral walls  7   b  continuing to each other. The housing  2  is provided with a locking hole  8 , into which a locking arm or the like of a mating connector fits, in the vicinity of an opening situated on this side of the housing  2  in  FIG. 1 . 
     As shown in  FIG. 6 , the set  3  of the terminal fittings includes a plurality of terminals  9 . Each terminal fitting  9  is made of metal and formed in a bar-shape. Each terminal fitting  9  is formed in a round bar-shape bent in an L-shape viewed from the side. The terminal fittings  9  are arranged in parallel to each other. One end part  9   a  of the terminal fitting  9  penetrates through the wall  7   a  and is received in the housing  2 , so that the terminal fittings  9  are held by the housing  2 . An opposite end part  9   b  of the terminal fitting  9  extends toward the outside of the housing  2 . The opposite end part  9   b  of terminal fitting  9  is fixed to the circuit pattern of the printed wiring board by brazing using solder or the like. 
     The inner shield shell  4  is formed in a square tube-shape by bending an electrically conductive sheet metal. As shown in  FIG. 4 , the inner shield shell  4  integrally includes a square tube-shaped shell body  10 , a back shell  11 , and a pair of fixing pieces  12 . The shell body  10  is formed in a square tube-shape and placed on outer surfaces of the peripheral walls  7   b  of the housing  2 , so that the shell body  10  receives the housing  2 . 
     The back shell  11  is formed in a flat plate-shape. The back shell  11  is formed by bending from the shell body  10  so as to continue to an end of the shell body  10  and to be parallel to the wall  7   a . The opposite end part  9   b  of the terminal fitting  9  is positioned between the back shell  11  and the wall  7   a . As shown in  FIG. 7 , the shell body  10  and the back shell  11  are provided with a fixing piece  13  and a fixing hole  14 , respectively, so as to fix the shell body  10  and the back shell  11  to each other. 
     The fixing pieces  12  are arranged in parallel to each other in a width direction of the housing  2  having a distance therebetween on a condition that the inner shield shell  4  covers the housing  2 . The pair of the fixing pieces  12  rises up from the shell body  10  toward the outside of the shell body  10 . The pair of the fixing pieces  12  is fixed to the circuit pattern of the printed wiring board by brazing using solder or the like. The pair of the fixing pieces  12  is placed closely on (i.e. closely comes in contact with) respective facing surfaces  19   a  (explained later). 
     The outer shield shell  5  is formed in a square tube-shape by bending an electrically conductive sheet metal. As shown in  FIG. 4 , the outer shield shell  5  integrally includes a square tube-shaped shell body  15 , a plurality of surface-fixing parts  16 , and a pair of fixing pieces  17 . 
     The shell body  15  includes a plurality of peripheral walls  18  (four walls  18  in an example shown in the figure) continuing to each other and is formed in a square tube-shape. The shell body  15  receives the inner shield shell  4  therein on a condition that the peripheral walls  18  are in parallel to the shell body  10  of the inner shield shell  4 . One peripheral wall  18  (hereinafter, indicated by  18   a ) of the shell body  15  is placed on the printed wiring board, so that the shell body  15  is fixed to the printed wiring board. 
     As shown in  FIG. 3 , this one peripheral wall  18   a  is provided with a notch  19 . The notch  19  is formed ranging from an end of the peripheral wall  18   a  on the side situated away from a mating connector (i.e. an end of the peripheral wall  18   a  situated in the vicinity of the opposite end part  9   b  of the terminal fitting  9 ) to a center of the peripheral wall  18   a  in a longitudinal direction of the peripheral wall  18   a . As shown in  FIG. 4 , an inner edge of the notch  19  is provided with a pair of facing surfaces  19   a  extending straight along the longitudinal direction of the shell body  15 . The facing surfaces  19   a  are arranged in parallel to each other in the width direction of the shell body  15  having a distance between the facing surfaces  19   a.    
     The surface-fixing part  16  is provided on the corresponding peripheral wall  18  and not provided on the peripheral wall  18   a . In an example shown in the figure, one surface-fixing part  16  is provided on one peripheral wall  18 . The surface-fixing part  16  is formed projecting from a central part of the peripheral wall  18  toward the inside of the shell body  15 . As shown in  FIGS. 5-7 , the surface-fixing part  16  is formed in parallel to the peripheral wall  18  and has a parallel wall  20  which is placed closely on (i.e. closely comes in contact with) an outer surface of the shell body  10  of the inner shield shell  4 . The parallel walls  20  are placed closely on (i.e. closely come in contact with) the respective outer surfaces of the shell body  10  of the inner shield shell  4 , so that the surface-fixing parts  16  position the inner shield shell  4  and the outer shield shell  5  and electrically connect the inner shield shell  4  and the outer shield shell  5  to each other. 
     The pair of the fixing pieces  17  rises up from both ends in the width direction of the one peripheral wall  18   a  (i.e. from both ends in the width direction of the notch  19 ) and is arranged in parallel to each other having a distance therebetween. The pair of the fixing pieces  17  rises up from the shell body  15  outside the shell body  15 . The pair of the fixing pieces  17  is fixed to the circuit pattern of the printed wiring board by brazing using solder or the like. 
     The fixing part  6  includes: a fixing projection  21  formed on one of the surface-fixing part  16  of the outer shield shell  5  and a portion of the inner shield shell  4  on which portion the surface-fixing part  16  is placed closely (in an example shown in the figure, the fixing projection  21  being formed on the portion of the inner shield shell  4  on which portion the surface-fixing part  16  is placed closely); and a fixing hole  22  formed on another of the surface-fixing part  16  of the outer shield shell  5  and a portion of the inner shield shell  4  on which portion the surface-fixing part  16  is placed closely (in the example shown in the figure, the fixing hole  22  being formed on the surface-fixing part  16  of the outer shield shell  5 ). The fixing projection  21  is formed by raising a part of the portion of the inner shield shell  4 , on which portion the surface-fixing part  16  is placed closely, toward the outside of the inner shield shell  4 . The fixing hole  22  is provided at a position of the fixing projection  21  and penetrates through the parallel wall  20  of the surface-fixing part  16 . The fixing projection  21  enters the fixing hole  22  and is locked in the fixing hole  22 , so that the fixing part  6  fixes the surface-fixing part  16  of the outer shield shell  5  and the portion of the inner shield shell  4 , on which portion the surface-fixing part  16  is placed closely, to each other. 
     The shield connector  1  having the structure described above is assembled as follows. First, each terminal fitting  9  is attached to the housing  2 , and each fixing piece  13  and the corresponding fixing hole  14  of the inner shield shell  4  are fixed to each other. Then, an end part of the shell body  10  of the inner shield shell  4 , said end part being situated away from the back shell  11 , is allowed to approach the opposite end part  9   b -side of the terminal fitting  9  of the housing  2  so as to insert the housing  2  into the shell body  10  of the inner shield shell  4 . Then, the inner shield shell  4  is positioned with respect to the housing  2  on a condition that the shell body  10  is matched with the whole outer surfaces of the housing  2  and the back shell  11  is situated having a distance from the opposite end part  9   b  of the terminal fitting  9 . 
     Then, an end part of the inner shield shell  4 , said end part being situated away from the back shell  11 , is inserted into the shell body  10  from an end part of the shell body  15  of the outer shield shell  5 , said end part being provided with the notch  19 . At that time, the opposite end part  9   b  of the terminal fitting  9  is positioned in the notch  19 . then, the parallel wall  20  of the surface-fixing part  16  is placed closely on (i.e. closely comes in contact with) an outer surface of the shell body  10  of the inner shield shell  4  and the pair of the fixing pieces  12  of the inner shield shell  4  is placed closely on (i.e. closely comes in contact with) the facing surface  19   a . Then, the fixing projection  21  of the fixing part  6  is allowed to enter the fixing hole  22  and locked in the fixing hole  22 , and the outer shield shell  5  and the inner shield shell  4  are fixed to each other, thereby assembling the shield connector  1 . Thus assembled shield connector  1  is placed on the printed wiring board, and the opposite end part  9   b  of the terminal fitting  9  and the fixing pieces  12  are electrically connected to the circuit pattern of the printed wiring board. 
     According to the preferred embodiment described above, since the outer shield shell  5  is provided with surface-fixing parts  16 , each of which is formed projecting from a peripheral wall  18  of the shell body  15  toward the inside of the shell body  15  and has a parallel wall  20 , which is placed closely on (i.e. closely comes in contact with) an outer surface of the inner shield shell  4 , therefore the outer shield shell  5  can be fixed without using an outer housing. Therefore, a gap between the inner shield shell  4  and the outer shield shell  5  can be prevented from occurring. Therefore, the terminal fittings  9  existing in the housing  2  can be securely electrically shielded from the outside. 
     Further, since the outer shield shell  5  is provided with surface-fixing parts  16 , each of which has a parallel wall  20 , which is placed closely on (i.e. closely comes in contact with) an outer surface of the shell body  10  of the inner shield shell  4 , therefore when the shield connector  1  is mounted on a motor vehicle, even if vibration during travelling of the motor vehicle takes place, the surface-fixing parts  16  come in close contact with the outer surfaces of the inner shield shell  4 , so that the inner shield shell  4  and the outer shield shell  5  can be securely electrically connected to each other. 
     Since the shield connector  1  further includes the fixing parts  6 , the surface-fixing part  16  of the outer shield shell  5  and the inner shield shell  4  can be securely fixed to each other, that is, the outer shield shell  5  and the inner shield shell  4  can be securely fixed to each other. Therefore, when the shield connector  1  is mounted on a motor vehicle, even if vibration during travelling of the motor vehicle takes place, the surface-fixing part  16  comes in close contact with an outer surface of the inner shield shell  4 , so that the inner shield shell  4  and the outer shield shell  5  can be further securely electrically connected to each other. 
     Since the fixing pieces  12  of the inner shield shell  4  are placed closely on (i.e. closely come in contact with) the respective facing surfaces  19   a  of the outer shield shell  5 , therefore the fixing pieces  12  can be prevented from being displaced after being fixed to the printed wiring board, so that electrical connection between the shield connector  1  and the printed wiring board can be prevented from being unstable. 
     In the preferred embodiment described above, the fixing projection  21  is provided on a portion of the inner shied shell  4 , on which portion the surface-fixing part  16  is placed closely, and the fixing hole  22  is provided in the surface-fixing part  16  of the outer shield shell  5 . However, instead, in the present invention, the fixing projection  21  may be provided on the surface-fixing part  16  of the outer shield shell  5  and the fixing hole  22  may be provided in a portion of the inner shied shell  4 , on which portion the surface-fixing part  16  is placed closely. 
     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.