Patent Publication Number: US-6981901-B2

Title: Terminal device of electrical apparatus

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to a terminal device provided in an electrical apparatus such as an electromagnetic contactor, a molded-case circuit breaker, and a terminal base. 
     A terminal device includes a box terminal device with a box fitting for directly connecting an end of a cable, and a terminal device for connecting a cable with a press terminal at an end thereof. Japanese Patent Publication (Kokai) No. 2002-190331 has disclosed a conventional box terminal device. 
       FIG. 7  to  FIG. 9  show a structure of the conventional box terminal device provided in an electromagnetic contactor.  FIG. 7  is a vertical cross sectional view showing the box terminal device,  FIG. 8  is a vertical cross sectional view showing the box terminal device in  FIG. 7  in a state in which a cable is connected thereto, and  FIG. 9  is an exploded perspective view showing the box terminal device in  FIG. 7 . In  FIG. 7  to  FIG. 9 , particularly in  FIG. 9 , a terminal strip  3  having a box-shaped terminal fitting  2  is attached to a terminal section provided in a frame  1  made of an insulation material. 
     In the terminal section, insulation walls  4  are formed on right-hand and left-hand sides of the terminal strip  3 . In each of the insulation walls  4  opposite to each other, a rectangular groove  5  (see  FIG. 9 ) is formed in the direction from the front to the rear. A box-like space  6  is formed between the opposing insulation walls  4  for holding the terminal fitting  2 . 
     Two projections  3   a  (see  FIG. 9 ) are formed on each of the right-hand and left-hand sides at an end of the terminal strip  3 . The terminal strip  3  is inserted into the grooves  5  from the front to the rear of the frame  1  with the projections  3   a  as shown by an arrow in  FIG. 9 . The terminal strip  3  is prevented from slipping off from the frame  1  with a pin  9  fitted to a bottom hole  8  in the terminal section through a through hole  7  (see  FIG. 9 ) in the terminal strip  3 . The terminal fitting  2  is formed in a box-like shape (rectangular) by die cutting and bending to be fitted slidably up and down to a recess between the projections  3   a  provided on each side of the terminal strip  3 . A terminal screw  10  with a hexagonal head hole is screwed into a threaded hole at a top of the terminal fitting  2  with a square washer  11  loosely coupled to the end of the terminal screw  10 . 
     In the terminal device, a stripped end of a cable  12  to be connected is directly inserted into both or one of the upper and lower sides of the terminal strip  3  to be held between the terminal fitting  2  and the terminal strip  3  by tightening the terminal screw  10 . A fixed contact point is attached to a right-hand end of the terminal strip  3  (not shown). 
       FIG. 10  to  FIG. 12  show a structure of a conventional terminal device for a press terminal provided in an electromagnetic contactor.  FIG. 10  is a vertical cross sectional view showing the terminal device,  FIG. 11  is a vertical cross sectional view showing the device in  FIG. 10  in a state in which a cable is connected thereto, and  FIG. 12  is an exploded perspective view showing the device in  FIG. 10 . In  FIG. 10  to  FIG. 12 , similar to the box terminal device, a terminal strip  3  to which a terminal screw  10  is screwed in is inserted in a groove  5  in an insulation wall  4  formed in a frame  1 . The terminal strip  3  is prevented form slipping off from the frame  1  with a screw section of the terminal screw  10  fitted into a cylinder-like recess  13  provided in the frame  1 . 
     In the terminal device, a cable  12  with a press terminal  14  crimped onto its end is secured to the terminal strip  3  by the terminal screw  10  with the press terminal  14  tightened onto the terminal strip  3 . A threaded hole of the terminal strip  3 , into which the terminal screw  10  is screwed, has a lower opening processed by burring. A recess  15  is formed around the cylinder-like recess  13  to accommodate a flanged portion  3   a  (see  FIG. 10 ) formed by burring. 
     In the conventional terminal devices described above, the box terminal device and the terminal device for a press terminal have their respective exclusive frames produced independently of each other. Therefore, for example, the frame for the box terminal device can not be used for the terminal device for the press terminal. Thus, when a connection system is changed after installation of an electrical apparatus, the whole apparatus has to be replaced. 
     In view of the problems described above, it is an object of the invention to provide a terminal device in which it is possible to easily switch between a cable with a stripped end and a cable with a press terminal. 
     Further objects and advantages of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     In order to attain the objects described above, according to a present invention, a terminal device of electrical apparatus includes a frame capable of receiving at least one conventional terminal strip having a box-shaped terminal fitting. The frame has at least two insulation walls provided in parallel with each other, each having a groove formed in the horizontal direction; a bottom plate made of an insulation material provided between the at least two insulation wails; and a wall standing from the bottom plate. The two adjacent insulation walls, the bottom plate, and the wall form a box-like space for holding the box-shaped terminal fitting. The terminal strip having a box-shaped terminal fitting is inserted into the grooves formed in the insulation walls, and the box-shaped terminal fitting is held in the box-like space with the terminal strip secured to the frame for preventing slip off. 
     According to the present invention, the terminal device of an electrical apparatus further includes at least one terminal strip having a terminal screw for a press terminal; and at least one attachment piece made of an insulation material and having a cylinder-like recess on an upper face and a projection on a lower face. The attachment piece has a size of being fitted in the box-like space. The bottom plate has a recess for engaging the projection on the lower face of the attachment piece. In a state that the terminal strip having a box-shaped terminal fitting is removed, the attachment piece is inserted in the box-like space, so that the projection on the lower face of the attachment piece is fitted to the recess formed in the bottom plate. The terminal strip having a terminal screw for a press terminal is inserted in the grooves formed in the insulation walls, so that a screw section of the terminal screw is fitted into the cylinder-like recess in the upper face of the attachment piece for preventing the terminal strip from slipping off and the terminal strip is attached to the attachment piece. 
     In the invention, when the attachment piece is attached and detached, it is possible to use a single frame commonly for both the box terminal device and the terminal device for a press terminal. 
     According to the invention, the attachment piece may be provided with a resilient claw on a back face thereof. The wall standing from the bottom plate may have a recess formed in a wall face facing the back face of the attachment piece at a position corresponding to the resilient claw, so that the recess engages the resilient claw to thereby hold the attachment piece. Accordingly, the attachment piece can be temporarily held in the frame before the terminal strip is inserted. 
     In the invention, when the attachment pieces of adjacent phases are connected with a coupling unit provided across the insulation wall between the attachment pieces, it is possible to handle the attachment pieces in a multiphase electrical apparatus as one-piece. 
     According to the invention, it is possible to use the common single frame for the box terminal device and the terminal device for a press terminal, thereby making it easy to change a cable connection system after an electrical apparatus is installed. It is also possible to reduce manufacturing cost of the frame and make inventory control simple. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross sectional view showing a structure of a terminal device provided as a box terminal device according to an embodiment of the invention; 
         FIG. 2  is a vertical cross sectional view showing the box terminal device shown in  FIG. 1  in a state in which a cable is connected thereto; 
         FIG. 3  is an exploded perspective view showing the box terminal device shown in  FIG. 1 . 
         FIG. 4  is a vertical cross sectional view showing the terminal device provided as a terminal device for a press terminal according to the embodiment of the invention; 
         FIG. 5  is a vertical cross sectional view showing the terminal device for a press terminal shown in  FIG. 4  in a state in which a cable is connected thereto; 
         FIG. 6  is an exploded perspective view showing the terminal device for a press terminal shown in  FIG. 4 ; 
         FIG. 7  is a vertical cross sectional view showing a structure of a conventional box terminal device; 
         FIG. 8  is a vertical cross sectional view showing the box terminal device shown in  FIG. 7  in a state in which a cable is connected thereto; 
         FIG. 9  is an exploded perspective view showing the box terminal device shown in  FIG. 7 ; 
         FIG. 10  is a vertical cross sectional view showing a structure of a conventional terminal device for a press terminal; 
         FIG. 11  is a vertical cross sectional view showing the terminal device for a press terminal shown in  FIG. 10  in a state in which a cable is connected thereto; and 
         FIG. 12  is an exploded perspective view showing the terminal device for a press terminal shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereunder, embodiments of the present invention will be explained with reference to  FIG. 1  to  FIG. 6 . The parts corresponding to those in the conventional devices are designated by the same reference numerals and signs.  FIG. 1  to  FIG. 3  show a terminal device provided as a box terminal device according to an embodiment of the invention.  FIG. 1  is a vertical cross sectional view showing a structure of the box terminal device,  FIG. 2  is a vertical cross sectional view showing the box terminal device in  FIG. 1  in a state in which a cable is connected thereto, and  FIG. 3  is an exploded perspective view showing the box terminal device in  FIG. 1 . 
     In  FIG. 1  to  FIG. 3 , differences from the conventional device in  FIG. 7  to  FIG. 9  are that a bottom plate of a frame  1  forming a box-like space  6  has a cylinder-like shallow recess  16 , and a wall standing from the bottom plate and forming the box-like space  6  has a rectangular shallow recess  17  (see  FIG. 3 ). Structures of a terminal fitting  2  and a terminal strip  3  are the same as those in the conventional terminal device. Similar to the conventional terminal device, a terminal strip  3  is attached to the frame  1 , and a stripped wire  12  is connected thereto. 
       FIG. 4  to  FIG. 6  show a terminal device provided as a terminal device for a press terminal as another embodiment according to the invention.  FIG. 4  is a vertical cross sectional view showing a structure of the terminal device for a press terminal,  FIG. 5  is a vertical cross sectional view showing the terminal device for a press terminal in  FIG. 4  in a state in which a cable is connected thereto, and  FIG. 6  is an exploded perspective view showing the terminal device for a press terminal in  FIG. 4 . 
     In  FIG. 4  to  FIG. 6 , difference from the conventional device in  FIG. 7  to  FIG. 9  are that an attachment piece  18  made of an insulation material is provided in the above frame  1  in addition to the recesses  16  and  17  therein. The attachment piece  18  is made of a molded resin like the frame  1 , and formed in a cube-like shape with its width and height fitting the box-like space  6  in the frame  1 . The attachment piece  18  has a cylinder-like recess  18   a  on the upper face thereof and a low column-like projection  18   b  (see  FIG. 4 ) on the lower face thereof. The column-like projection  18   b  fits the recess  16  in the bottom plate of the frame  1  forming the box-like space  6 . 
     On the back of the attachment piece  18 , a resilient claw  18   c  is provided for fitting into the recess  17  in the surface of the wall standing from the bottom plate forming the box-like space  6  in the frame  1 . The resilient claw  18   c  is formed in a tongue-like piece flexibly standing with a clearance provided between surroundings. In a three-phase electromagnetic contactor, three attachment pieces  18  are used as shown in  FIG. 6 . Of the three attachment pieces  18 , two attachment pieces  18  of adjacent phases are coupled to each other by a U-shape coupling unit  19  provided across an insulation wall  4 . The structure of a terminal strip  3  having a terminal screw  10  is the same as that in the conventional terminal device. 
     In the terminal device shown in  FIG. 4  to  FIG. 6 , when the terminal device for a press terminal is attached to the frame  1  instead of the box terminal device, the attachment piece  18  is first inserted into the box-like space  6  in a state that the box terminal device is removed. At this time, the projection  18   b  is fitted to the recess  16  in the surface of the bottom plate of the frame  1  forming the box-like space  6 . 
     The resilient claw  18   c  on the back of the attachment piece  18  is fitted to the recess  17  in the surface of the wall standing from the bottom plate and forming the box-like space  6 . In this state, the attachment piece  18  is restrained from moving back and forth and moving up and down by the projection  18   b  and the resilient claw  18   c , respectively, to be temporarily held in the frame  1 . Then, the terminal strip  3  with the terminal screw  10  detached is inserted into the groove  5  to position the threaded hole in the terminal strip  3  for the terminal screw  10  over the cylinder-like recess  18   a  in the attachment piece  18 . Then, the terminal screw  10  is screwed into the terminal strip  3  to fit the threaded section of the screw  10  into the cylinder-like recess  18   a  in the attachment piece  18 . Accordingly, the terminal strip  3  does not slip off from the attachment piece  18 . 
     To the terminal strip  3 , a cable  12  provided with a press terminal  14  is connected in the same way as in the conventional device. For avoiding the flanged portion  3   a  protruding from the terminal strip  3 , the upper face of the attachment piece  18  is recessed by providing a step  18   d.    
     In the embodiments, by only attaching the attachment piece  18 , the frame  1  for a box terminal device can be commonly used for a terminal device for a press terminal without an exclusive frame for each of the terminal devices. Therefore, even after an electromagnetic contactor is installed, connection system can be changed without replacing the main body of the contactor. In manufacturing a magnetic contactor, the number of frames is reduced, thereby reducing manufacturing cost and making inventory control easy. Furthermore, by making the attachment piece  18  temporarily held to the frame  1  with the resilient claw  18   c  and by making attachment pieces for multiphase terminals integrated with the coupling units  19 , assembling work of the terminal device becomes easy. 
     In the embodiments, the electromagnetic contactor is shown as an example of the electrical-apparatus. The invention can be applied to other kinds of electrical apparatus having terminal devices such as a molded-case circuit breaker and a terminal base. 
     The disclosure of the Japanese Patent Application No. 2004-140733 filed on May 11, 2004 is incorporated in the application. 
     While the present invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.