Abstract:
The cables are configured to supply electric power from an inverter to a motor. The cables include a connector and plural terminals fixed to the connector. A housing of the connector includes a first rib, provided between the adjacent terminals, connecting mutually facing surfaces of the housing. The terminal block is attached to an enclosure of the inverter or motor. The terminal block includes plural retaining walls, each of which encloses and retains a nut. The terminal block includes a second rib connecting adjacent retaining walls. One of the first and second ribs includes a recess. The connector is connected to the terminal block when each of the terminals is fastened to the terminal block with a bolt and the nut. The other of the first and second ribs is disposed in the recess and the ribs intersect when the connector is connected to the terminal block.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The disclosure of Japanese Patent Application No. 2013-004634 filed on Jan. 15, 2013 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a connecting apparatus between a terminal block that is attached to an enclosure of an inverter or a motor and power cables that supply electric power from the inverter to the motor. 
         [0004]    2. Description of Related Art 
         [0005]    An electric vehicle includes a motor for driving, and an inverter that converts direct-current power of a battery into alternating-current power with a suitable frequency for driving the motor. A cable for supplying the electric power from the inverter to the motor is often referred to as a power cable because the cable passes a large current. An enclosure of the inverter is connected to an enclosure of the motor with power cables. A connector is attached to an end of the power cables, while the enclosure of the inverter or the motor is provided with a terminal block that couples with the connector. 
         [0006]    The driving motor for the electric vehicle requires a large amount of the electric power in particular. Consequently, each of the power cables has a large diameter and high stiffness, and thus a connecting structure between the connector and the terminal block requires high strength. Accordingly, Japanese Patent Application Publication No. 2011-177002 (JP 2011-177002 A) and Japanese Patent Application Publication No. 2012-160355 (JP 2012-160355 A) disclose the techniques for increasing the strength of the terminal blocks in particular. In the techniques disclosed in JP 2011-177002 A and JP 2012-160355 A, nuts are aligned in the terminal block for fastening the terminal of the connector in the power cable with bolts. In addition, partition panels (JP 2011-177002 A) or ribs (JP 2012-160355 A) are provided between the adjacent nuts to increase strength of the terminal block. 
       SUMMARY OF THE INVENTION 
       [0007]    When a structural strength is increased in general, the size of the connector or the terminal block also increases. The present invention provides a technique for preventing the increase in size and increasing the strength of both the connector and the terminal block, and a technique for limiting the increase in size and securing the strength by taking advantage of structural features of the connector and the terminal block that are fitted with each other. 
         [0008]    Aspects of the present invention relate to a connecting apparatus. The connecting apparatus includes power cables and a terminal block. The power cables are configured to supply electric power from an inverter to a motor. The power cables include a connector and a plurality of terminals. The plurality of terminals are fixed to the connector. A housing of the connector includes a first rib. The first rib is provided between the adjacent terminals. The first rib connects mutually facing surfaces of the housing. The terminal block is attached to an enclosure of the inverter or an enclosure of the motor. The terminal block includes a plurality of retaining walls. Each of the plurality of retaining walls encloses and retains a nut. The terminal block includes a second rib for connecting the adjacent retaining walls. One of the first rib and the second rib includes a recess. The connector is connected to the terminal block when each of the plurality of terminals is fastened to the terminal block with a bolt and the nut. The other of the first rib and the second rib is disposed in the recess and the first rib intersects with the second rib when the connector is connected to the terminal block. 
         [0009]    The plurality of cable terminals are fixed to the connector in the end of the power cables. In addition, the terminal block connected to the connector is provided with retaining walls that corresponds to each of the plurality of cable terminals and encloses and retains the nut fastening the cable connector with the bolt. In the aspect of the present invention, the connector is provided with the first rib that is provided between the adjacent terminals and connects the mutually facing surfaces of the housing of the connector to increase the strength. On the other hand, the terminal block is provided with second rib for connecting the adjacent retaining walls to increase the strength. In the aspect of the present invention, either one of the first rib and the second rib is provided with the recess, and the first rib and the second rib have the positional relation in which one rib intersects with the recess provided in the other rib when the connector is connected to the terminal block. The reduction of the space where the two ribs occupy can be achieved by intersecting the two ribs. It should be noted that both of the ribs may be provided with the recess, and the positional relation of the two ribs can be determined so that the recesses face and intersect with each other. 
         [0010]    The technique described above is particularly effective to the connector in which the plurality of the cable terminals are arranged in a line for the following reasons. When the plurality of the cable terminals are arranged in a line, the connector housing is formed in a long narrow shape. Then, the strength decreases. Providing the first rib that crosses the housing in the vicinity of a near midsection of the connector housing in the longitudinal direction is effective at increasing the strength. On the other hand, the nuts in the terminal block are arranged in a line in accordance with the arrangement of the cable terminals in the connector. In such a structure, the second rib for connecting the adjacent retaining walls of the adjacent nuts extends in the direction of the nut arrangement, that is, the longitudinal direction of the connector housing. Thus, the direction in which the first rib extends intersects with the direction in which the second rib extends, and the advantage in applying the technique disclosed herein can be achieved. A typical case is that electric power is supplied from the enclosure of one inverter to two motors. In this case, at least six cable terminals are arranged in a line in the connector to supply the electric power to each of the two motors. In the terminal block provided in the enclosure of the inverter, six nuts for fastening the cable terminals are arranged in a line, corresponding to the at least six cable terminals. The connector housing is formed in a long narrow shape corresponding to the arrangement of the six nuts in a line. In such connector and terminal block, the ribs described above are effective at securing the strength of the connector. 
         [0011]    It should be noted that the technique disclosed herein may be applicable to the connecting structure between the terminal block provided in the enclosure of the inverter and the power cables, or to the connecting structure between the terminal block provided in the enclosure of the motor and the power cables. The connector housing corresponds to a connector that fixes the cable terminals. 
         [0012]    Furthermore, the first rib may be provided on a terminal block side rather than in the cable terminal when the connector is connected to the terminal block. Such a structure can reduce the thickness of the connector because the two ribs intersect with each other through the recess in the direction of the connector thickness (the length of the connector housing in the direction of insertion into the terminal block). 
         [0013]    The recess provided in the rib can be used for recognizing the direction of the connector when the operator connects the connector to the terminal block. To do this, the recess of the rib may be provided at a position offset from the center of the opening of the connector to the edge of the opening. When the present invention includes such a structure, the recess cannot be fitted into the other rib in position in the case where the direction of the connector is wrong. Therefore, the operator can be prevented from mistaking the direction of the connector. 
         [0014]    Details of the technique disclosed herein and further modifications will be described in the following “DETAILED DESCRIPTION OF EMBODIMENTS”. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
           [0016]      FIG. 1  is a perspective view of a connector and a terminal block; 
           [0017]      FIG. 2  is a cross-sectional view of the terminal block and the connector that are taken along the line II-II in  FIG. 1 ; 
           [0018]      FIG. 3A  is a bottom view of the connector, and  FIG. 3B  is a plan view of the terminal block; 
           [0019]      FIG. 4  is a cross-sectional view of the terminal block and the connector that are taken along the line IV-IV in  FIG. 2 ; 
           [0020]      FIG. 5  is a cross-sectional view during the connection of the terminal block and the connector that are taken along the line IV-IV in  FIG. 2 ; and 
           [0021]      FIG. 6  is a cross-sectional view during the connection of the terminal block and the connector that are taken along the line VI-VI in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0022]    A connecting structure of an embodiment will be described with reference to the drawings. The connecting structure of the embodiment includes a terminal block that is provided to an inverter for an electric vehicle and a connector for power cables that are attached to the terminal block.  FIG. 1  shows a perspective view of a connector  10  and a terminal block  20 .  FIG. 2  shows a cross-sectional view that is taken along the line II-II in  FIG. 1 . The terminal block  20  is mounted on an inverter  92 . The inverter  92  supplies electric power to two motors individually, and thus the connector  10  and the terminal block  20  include six pairs of terminals. Six power cables  91  extend from the connector  10 . These power cables  91  are connected to two motors (not shown) with three cables each. 
         [0023]    An enclosure of the connector  10  includes a connector housing  13  that fixes cable terminals  15  (see  FIG. 2 ) and a cover  12 . The six cable terminals  15  are individually connected to the six power cables  91  in the connector. The connector housing  13  has a cylindrical shape and is fitted into a cylindrical terminal block housing  21  of the terminal block  20 . An O ring  14  (ring packing) is fitted around the connector housing  13  for sealing between the connector housing  13  and the terminal block housing  21  when the connector housing  13  is fitted into the terminal block housing  21 . The cover  12  is removable from the connector housing  13  in order that a bolt can be inserted when the cable terminal  15  in the connector is fastened to a nut  24  in the terminal block  20 . Both of the connector housing  13  and the cover  12  are made of resin. 
         [0024]    In the terminal block  20 , a set of the nut  24 , a bus bar  23 , and a retaining wall  22  configures a terminal unit  25 . The nut  24  is provided to fix the bolt that fastens the cable terminal  15  in the connector  10  as described above. For reference, the bolt  94  is shown with phantom lines on the extreme right in  FIG. 2 . When the bolt  94  is fastened, the cover  12  is removed. The nut  24  is enclosed and fixed with the retaining wall  22  together with the terminal block housing  21  as one unit. The retaining wall  22  has a shape of a Greek letter π (or a letter U), and the nut  24  is fixed inside the π-shape. The retaining wall  22  has a function of fixing the nut  24  and also a function of retaining the bus bar  23 . The bus bar  23  is a conductor that comes into contact with the cable terminal  15  and transmits the electric power from a circuit in the inverter to one of the power cables. The bus bar  23  is a long narrow plate of metal that has small internal resistance such as copper. An end of the bus bar  23  is extended along inner walls and a top surface of the II-shaped retaining wall  22 . When the cable terminal  15  is fastened to the nut  24  with the bolt  94 , the end of the bus bar  23  that extends on the top surface of the π-shaped retaining wall  22  comes into close contact with the cable terminal  15 , and the bus bar  23  and the cable terminal  15  can conduct. A body  23   a  of the bus bar  23  passes through the terminal block housing  21  and is connected to the circuit (not shown) in the inverter  92 . 
         [0025]    In  FIG. 2 , reference numerals are given to only the cable terminal  15  and the terminal unit  25  on the extreme left. Although reference numerals are not given to the other five cable terminals and terminal units, all those components have the same structure as the cable terminal  15  and the terminal unit  25  on the extreme left. In addition, all the cable terminals  15  are fastened to the terminal units  25  (nuts  24 ) with the bolts  94 . 
         [0026]    As clearly shown in  FIG. 1  and  FIG. 2 , the six cable terminals  15  in the connector  10  are arranged in a line, and the connector  10  has a long narrow shape. The connector housing  13  is provided with a first rib  16  that crosses the connector housing  13  in a near midsection inside the cylindrical part.  FIG. 3A  shows a bottom view of the connector  10  (a diagram in which the connector  10  is viewed toward the positive direction of Z-axis in the coordinate system in the drawing). As clearly understood with reference to  FIG. 2  and  FIG. 3A , the first rib  16  crosses the connector housing  13  in between the two adjacent cable terminals  15  in the midsection of the cylindrical part that has a long narrow opening. The first rib  16  contributes to an increase in strength of the connector housing  13 . A recess (notch)  17  is provided in the edge of the first rib  16  that faces the terminal block  20 . The recess  17  will be described later. 
         [0027]    In the terminal block  20 , adjacent retaining walls  22  (terminal units  25 ) are connected to each other with a second rib  26 . The second rib  26  contributes to an increase in strength of the retaining wall  22  (that is, strength of the terminal block  20 ).  FIG. 3B  shows a plan view of the terminal block  20  (a diagram in which the terminal block  20  is viewed toward the negative direction of Z-axis in the coordinate system in the drawing). As clearly shown in  FIGS. 3A and 3B , the first rib  16  extends along the X-axis in the coordinate system in the drawing, and the second rib  26  extends along the Y-axis. In other words, the first rib  16  and the second rib  26  have a positional relation in which the first rib  16  and the second rib  26  cross each other when the connector  10  is connected to the terminal block  20 . In addition, the second rib  26  is arranged inside the recess  17  that is provided in the first rib  16  when the connector  10  is connected to the terminal block  20 . The advantage of the recess  17  is described next. 
         [0028]      FIG. 4  shows a cross-sectional view that is taken along the line IV-IV in  FIG. 2 .  FIG. 4  also shows a cross section of the first rib  16  which is taken along the longitudinal direction of the first rib  16 . In addition,  FIG. 5  is a cross-sectional view that corresponds to  FIG. 4  and shows a cross section of the connector  10  and the terminal block  20  when they are connected. As described above, when the connector  10  is connected to the terminal block  20 , the first rib  16  and the second rib  26  have the positional relation in which one rib (second rib  26 ) is placed in the recess  17  of the other rib (first rib  16 ) and one rib intersects with the other rib as seen from the direction in which the connector  10  is connected to the terminal block  20 . Consequently, when the connector  10  is connected to the terminal block  20 , the first rib  16  and the second rib  26  overlap with each other in a connecting direction of the connector  10  to the terminal block  20 . The height of the connector  10  and the terminal block  20  when they are connected (the length shown with a reference symbol H in  FIG. 5 ) can be reduced by the overlap. The recess  17  can restrain the increase in size due to the rib provided for increasing the strength of both the connector  10  and the terminal block  20 . 
         [0029]    The first rib  16  is placed at the position closer to the terminal block  20  than the cable terminal  15 . As clearly shown in  FIG. 5 , this position is included in a space where the cylindrical part of the connector housing  13  is fitted into the terminal block housing  21  in the insertion direction of the connector  10 . In other words, the space where the first rib  16  is placed is an originally necessary space, and thus the increase in space by providing the first rib  16  is limited. 
         [0030]    Furthermore, the facts that an upper end of the first rib  16  in  FIG. 4  (an edge of the first rib  16  that is positioned farthest from terminal block  20 ) is placed at the position closer to the terminal block  20  than the cable terminal  15  and does not protrude on the back side of the cable terminal  15  offer the following advantage. The back side of the cable terminal  15  means an opposite surface to the terminal block  20 . The bolt  94  (see  FIG. 5 ) is inserted from the back side of the cable terminal  15  for fastening the cable terminal  15  on the terminal unit  25 . The first rib  16  does not protrude on the back side of the cable terminal  15 , and thus the first rib  16  does not hinder the bolt  94  from fastening. Conversely, when the first rib  16  protrudes on the back side of the cable terminal  15 , the clearance between the cable terminals  15  on the sides of the first rib  16  is required to be expanded so that a tool for fastening the bolt  94  does not come into contact with the first rib  16 , and the size of the connector  10  and thus the size of the terminal block  20  may increase by the expansion. The first rib  16  does not protrude on the back side of the cable terminal  15 , and consequently, the connector  10  and/or the terminal block  20  can be made more compact in size. 
         [0031]    On the other hand, the recess  17  that is provided in the first rib  16  has another function. As shown in  FIG. 4 , the recess  17  is provided at a position offset from the center CN of the opening of the connector housing  13  to the right edge of the opening (right end side of the first rib  16  in the drawing). Thus, when the direction of the connector  10  is wrong, the second rib  26  does not face the recess  17 . In this state, the connector  10  cannot fit into the terminal block  20  correctly. Even when the operator tries to attach the connector  10  to the terminal block  20  in the wrong direction, the connector  10  cannot fit into the terminal block  20  correctly, and thus the operator cognize a mistake. That is to say, the installation workability of the connector  10  can be enhanced by providing the recess  17  misaligned from the center of the opening. 
         [0032]    For reference,  FIG. 6  shows a cross-sectional view that taken along the line VI-VI in  FIG. 2 . The cable terminals  15  comes into close contact with the end of the bus bar  23  when fastened to the nut  24  of the terminal block  20  with the bolt, and thus the connector  10  and the terminal block  20  can conduct. 
         [0033]    Considerations about the technique described in the embodiment will be described. The connecting structure according to the embodiment is achieved by the terminal block  20  provided in the inverter  92  and the connector  10  in the end of the power cables  91  for supplying the electric power from the inverter to the motor. The connecting structure disclosed herein may be applied to the terminal block provided in the enclosure of the motor and the connector in the end of the power cables. In this case, the structure in which the reference numeral  92  denotes in  FIG. 1  through  FIG. 6  corresponds to the enclosure of the motor. 
         [0034]    In the connector  10  and/or the terminal block  20  of the embodiment, six terminals (the cable terminals  15  and the bus bar  23 ) are arranged in a line. In such a layout, both of the connector  10  and the terminal block  20  are formed to be long and narrow, and thus the strength is hardly secured. The technique disclosed herein is preferable to the case where the connector and the terminal block has such a long narrow form. However, the technique disclosed herein is not limited to the case where the six terminals are arranged in a line. 
         [0035]    In the embodiment, the recess  17  is disposed in the first rib  16  that is provided in the connector housing  13 . The recess may be disposed in the second rib  26  that is provided in the terminal block housing  21 . The present invention may be configured such that both of the first rib and the second rib are provided with the recesses, and the recess in the first rib intersects with the recess in the second rib when the connector  10  is coupled to the terminal block  20 . 
         [0036]    In the embodiment, the first rib  16  is provided in the near midsection of the connector housing  13  in the longitudinal direction. However, the position where the first rib  16  is provided is not limited to the position described above. 
         [0037]    While the present invention has been described in detail with reference to example embodiments thereof, it is to be understood that those examples are merely illustrative and claims of the present invention are not limited to those examples. The techniques that are disclosed in the claims of the present invention are intended to cover various modifications and changes of the example embodiments that are described above. In addition, the technical elements that are disclosed in the specification and the drawings exhibit technical usefulness alone or in various combinations and configurations, and those are not limited to the combinations and configurations that are disclosed in the claims at the time of filing this application. The techniques that are illustrated in the specification and the drawings can achieve a plurality of objects simultaneously, and the achievement of one object thereof itself has technical usefulness.