Abstract:
The power shut-off unit is equipped with two relays ( 2 ) connected to an external circuit, and a tabular baseplate ( 6 ). Multiple auxiliary electronic components ( 7 ) are mounted on the baseplate ( 6 ). The relays ( 2 ) are held so as to float over a mounting surface ( 13 ) via a pair of retaining members ( 8 ). A distance (d) equal to or greater than the thickness of the baseplate ( 6 ) is maintained between the relays ( 2 ) and the mounting surface ( 13 ). The baseplate ( 6 ) is not directly fixed to the mounting surface ( 13 ) and is connected to the relays ( 2 ) via multiple latching members ( 9 ). Because no load is acted upon the baseplate ( 6 ) by the relays ( 2 ), the baseplate ( 6 ) can be made thin.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a power shut-off unit that is used for an electric vehicle or the like. 
       BACKGROUND ART 
       [0002]    A junction box which functions as a general power shut-off unit is provided in a power-source circuit of a battery. The junction box includes electronic components such as a relay(s) and a fuse(s) which conduct opening and closing (shut-off) of the power-source circuit and which distribute power among accessory components of a vehicle. 
         [0003]    Patent Literature 1 discloses one example of the junction box. In this technique, when the electronic component has failed, only the electronic component can be checked and replaced easily, inexpensively and quickly in the course of using a battery. 
         [0004]    In the case of the junction box disclosed in the Patent Literature 1, various electronic components and a relay for shutting off a power circuit are integrated with each other and are fastened to a battery frame. In this example, the plurality of electronic components are fixed to an inside of the junction box, and the relay is fixed to an upper surface of the junction box. This junction box itself is fixed to a lower case of the battery. 
         [0005]    In an electric vehicle and the like, a large-size relay is used to deal with high voltages. In the technique disclosed in the Patent Literature 1, the relay having a heavy weight is provided on the upper surface of the junction box. Hence, there is a risk that a plate portion of the junction box on which the relay is mounted sags or bends resulting in rupture or breakage thereof due to a running vibration or the like of the vehicle. Therefore, it is necessary to thicken the plate portion in order to strengthen this plate portion. Accordingly, an unfavorable weight increase is caused. 
       CITATION LIST 
     Patent Literature 
       [0006]    Patent Literature 1: Japanese Patent Application Publication No. 2006-228526 
       SUMMARY OF THE INVENTION 
       [0007]    According to the present invention, a power shut-off unit includes a relay connected to an external circuit; a base plate formed in a tabular shape; and various electronic components except the relay (i.e., auxiliary electronic components), wherein the relay and the various electronic components are arranged above the base plate, wherein the relay is supported through a retaining member by a mounting surface such that a distance between the relay and the mounting surface is greater than or equal to a thickness of the base plate, wherein the base plate is connected with the relay by a latching member and is located between the relay and the mounting surface. 
         [0008]    According to such a power shut-off unit, the relay and the auxiliary electronic component are arranged above the base plate. Hence, there is an advantage that the relay and/or the auxiliary electronic component can be checked and replaced easily, inexpensively and quickly when the relay and/or the auxiliary electronic component has failed. Moreover, a load of the relay having the heavy weight does not applied to the base plate, so that a required strength of the base plate can be lowered. 
     
    
     
       BRIEF EXPLANATION OF DRAWINGS 
         [0009]      FIG. 1  An electric circuit diagram showing a part of a power-source circuit for an electric vehicle, in which a power shut-off unit is used. 
           [0010]      FIG. 2  A plan view showing a first embodiment of the power shut-off unit according to the present invention. 
           [0011]      FIG. 3  A cross-sectional view of a part of the power shut-off unit, taken along a line A-A of  FIG. 2 . 
           [0012]      FIG. 4  A cross-sectional view of a part of the power shut-off unit, taken along a line B-B of  FIG. 2 . 
           [0013]      FIG. 5  A cross-sectional view of a part of the power shut-off unit, taken along a line C-C of  FIG. 2 . 
           [0014]      FIG. 6  A plan view showing a second embodiment of the power shut-off unit according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0015]    Hereinafter, a first embodiment according to the present invention will be explained referring to  FIGS. 1 to 4 . In the respective figures, the same element has an identical reference sign, and thereby, the repetition of explanation thereof will be omitted. X-axis and Y-axis indicated in  FIGS. 2 to 4  show mutually-perpendicular two directions that are along an after-mentioned mounting surface  13 . Z-axis indicated in  FIGS. 2 to 4  shows a direction perpendicular to the mounting surface  13 . 
         [0016]      FIG. 1  is an electric circuit diagram showing a part of a power-source circuit for an electric vehicle, in which a power shut-off unit  1  according to the present invention is used. The power shut-off unit  1  is provided in the power-source circuit as a part of a battery pack  5 . The power shut-off unit  1  includes a relay(s)  2  and a fuse(s)  3 . The power shut-off unit  1  functions as a breaker device which connects a battery  4  with an inverter (INV) and/or a DC-DC converter (DC/DC) and which disconnects the battery  4  from the inverter (INV) and/or the DC-DC converter (DC/DC), i.e. shuts off a power supply of the battery  4 . It is noted that the battery  4  supplies power through the power shut-off unit  1  also to some accessory components of the vehicle, such as an air conditioner (A/C). 
         [0017]      FIG. 2  is a plan view of the power shut-off unit  1  as viewed from above in the first embodiment (harness not shown). The power shut-off unit  1  is attached to the mounting surface  13  located inside a case of the battery pack  5 . This battery pack  5  is, for example, mounted on a lower side of a floor of the electric vehicle. 
         [0018]    The power shut-off unit  1  includes a base plate  6  formed in a rectangular plate shape. That is, the base plate  6  is in a tabular shape extending in the X-axis and Y-axis directions on X-Y plane. The base plate  6  includes a pair of side edges (boarders)  6   a  which are parallel to X-axis, and a pair of side edges (boarders)  6   b  which are parallel to Y-axis. The side edge  6   a  is longer than the side edge  6   b  so that the base plate  6  extends longer in the X-axis direction than in the Y-axis direction. The two relays  2  and a plurality of auxiliary electronic components  7  that are connected to an external circuit(s) are arranged on or above the base plate  6  so as to be collectively packaged as one unit. Therefore, when the relay  2  or the auxiliary electronic component  7  fails, an inspection and/or repair can be conducted easily, quickly and at low cost. 
         [0019]    Each relay  2  can be used for high voltages, and is enclosed or sealed in a case formed in a rectangular-parallelepiped shape. As shown in  FIG. 2 , each relay  2  is disposed on the base plate  6  such that a longitudinal direction of the relay  2  accords with the Y-axis direction. A pair of bracket portions  2   a  are formed respectively at both the opposed side surfaces of the case of each relay  2 . Each bracket portion  2   a  is constituted by an arm of the case of the relay  2 , and is in a forked shape. The two bracket portions  2   a  of each relay  2  are located asymmetrically from each other. 
         [0020]    Each relay  2  is supported by the mounting surface  13  through retaining members  8 . Each retaining member  8  is formed substantially in a cylindrical-column shape. This retaining member  8  gives or defines a positional relation between the relay  2  and the mounting surface  13 . Each retaining member  8  is attached to the bracket portion  2   a  of the relay  2 . In each relay  2 , the locations of the pair of bracket portions  2   a , i.e. locations of the pair of retaining members  8  are asymmetrical as mentioned above, and are offset from each other with respect to the Y-axis direction. That is, when giving a reference sign  8 A to the retaining member  8  of one side surface of the relay  2  and giving a reference sign  8 B to the retaining member  8  of another side surface of the relay  2 , the location of the retaining member  8 A is shifted (offset) from the location of the retaining member  8 B in the Y-axis direction as shown in  FIG. 2 . Since two fixing points at which the relay  2  is fixed to the mounting surface  13  are shifted (offset) from each other, a rotational moment of the relay  2  is restricted more effectively. Hence, each relay  2  is stably supported by the mounting surface  13 . Moreover, since the retaining members  8 A and  8 B are provided on the side surfaces of the relay  2  which are parallel to the Y-axis direction, a length of the base plate  6  in the Y-axis direction can be shortened. Accordingly, an area (dimensions) of the base plate  6  can be made small. 
         [0021]    The two relays  2  each including the bracket portions  2   a  fundamentally have the same structure as each other. As shown in  FIG. 2 , one of the two relays  2  is arranged to face in a direction opposite to a facing direction of another of the two relays  2 , on the base plate  6 . That is, the two relays  2  have postures opposite to each other. 
         [0022]    The base plate  6  is supported by the relays  2  through a plurality of latching members (or locking members)  9 . The plurality of latching members  9  are provided into the base plate  6 . That is, the plurality of latching members  9  connects the base plate  6  with the relays  2 . The base plate  6  is not directly fixed to the mounting surface  13 . 
         [0023]    As compared with the conventional structure in which the base plate is fixed to the mounting surface by four bolts provided at four corners of the base plate, the area of the base plate  6  can be made small because fastening portions by the bolts are unnecessary according to the present invention. 
         [0024]    The auxiliary electronic components  7  include a resistor  7 A and a harness connector portion(s)  7 B and the like. The harness connector portion(s)  7 B is continuous from the battery  4 , the inverter and the accessory components and the like. At least two relays  2  each having the rectangular-parallelepiped shape are disposed to form a proper space between the at least two relays  2 , and the auxiliary electronic components  7  are disposed between the adjacent two relays  2 . Accordingly, the area of the base plate  6  can be reduced. 
         [0025]      FIG. 3  is a cross-sectional view taken along a line A-A of  FIG. 2  as viewed from a lateral direction of the power shut-off unit  1  in the first embodiment. As mentioned above, the relay  2  is supported through the retaining members  8  on the mounting surface  13 . With respect to Z-axis direction, the retaining members  8  maintain a distance d between a bottom surface of the relay  2  and the mounting surface  13  at a value greater than or equal to a thickness of the base plate  6 . As a result, a load of the relay  2  is not applied to the base plate  6 . Hence, it is not necessary for the base plate  6  to support the load of each relay  2 . Therefore, a necessary strength of the base plate  6  is lowered. In a more preferred embodiment, the distance d between the bottom surface of the relay  2  and the mounting surface  13  is set to be substantially equal to the thickness of the base plate  6  so that a lower surface  6   a  of the base plate  6  is substantially in contact with the mounting surface  13  as shown in the figures. Depending on circumstances, a minute clearance may be formed and kept between the lower surface  6   a  of the base plate  6  and the mounting surface  13 . 
         [0026]    According to the present invention, the strength necessary for the base plate  6  is lowered while the area of the base plate  6  is reduced. Hence, a weight reduction can be achieved. Therefore, it is unnecessary to fasten the base plate  6  to the relay  2  by means of bolt fastening. Instead, the base plate  6  can be held by the latching members  9 . Each latching member  9  includes an arm portion  10  and a latching hook (locking claw)  11 . The arm portion  10  extends from an upper surface of the base plate  6  in the Z-axis direction. The latching hook  11  is provided at a tip of the arm portion  10 . In the first embodiment, the base plate  6  is made of synthetic resin, and each latching member  9  is molded integrally with the base plate  6 . Engaging protrusions  12  are formed in side walls of the relay  2  at locations corresponding to the latching members  9 . Each engaging protrusion  12  engages with the latching hook  11 . That is, the latching hook  11  of the latching member  9  is engaged with the engaging protrusion  12  by means of elasticity of the arm portion  10 , and thereby, the relay  2  and the babe plate  6  are connected (combined) with each other. Therefore, a connecting operation between the relays  2  and the base plate  6  becomes easy resulting in cost reduction. 
         [0027]    The engaging protrusion  12  may be defined by a convex-concave normally existing in an outer surface of the relay  2 . For example, the latching hook  11  may be hooked directly on an upper surface of the relay  2 . 
         [0028]    Moreover, the latching member  9  including the latching hook  11  at the tip of the latching member  9  may be provided in the relay  2  whereas a notch or an opening which is engaged with this latching member  9  may be provided in the base plate  6 . 
         [0029]    For the purpose of stably holding the relay  2 , it is desirable to arrange the four latching members  9  respectively at four sides (edges) of the rectangular relay  2 . However, as shown in  FIG. 2 , a connection terminal  21  that is connected to the external circuit(s) is provided on a wall of one end portion of the relay  2 , so that the latching member  9  cannot be arranged on the wall of the one end portion of the relay  2 . Therefore, in the example shown in  FIG. 2 , the three latching members  9  are arranged respectively at three spots (three sides) of each relay  2 . That is, the latching members  9  include one latching member  9 A provided on a wall of another end portion of the relay  2 , and a pair of latching members  9 B provided to face each other on both opposed surfaces of the one end portion of the relay  2  which are near the connection terminal  21 . The two relays  2  are arranged in the postures reversed relative to each other as mentioned above. As shown in  FIG. 2 , the connection terminal  21  of one of the two relays  2  is located in an opposite side of a center line CL passing through (centers of) the two relays  2 , from the connection terminal  21  of another of the two relays  2 . That is, the center line CL is sandwiched between the connection terminals  21  of the two relays  2 . In the same manner, the latching member  9 A of the one of the two relays  2  faces in a direction opposite to a facing direction of the latching member  9 A of the another of the two relays  2 . By such an arrangement, even without providing the latching member  9  on the side (edge) of the relay  2  on which the connection terminal  21  is provided, the relays  2  can be stably connected with the base plate  6 . As a result, the number of necessary latching members  9  can be reduced. 
         [0030]    As mentioned above, the distance d between the relay  2  and the mounting surface  13  is set to be equal to the thickness of the base plate  6  so that the lower surface  6   a  of the base plate  6  is in contact with the mounting surface  13 . Accordingly, the base plate  6  does not drop even if the latching member  9  is broken. Accordingly, a flapping that is caused due to a vehicle vibration and the like can be prevented. 
         [0031]      FIGS. 4 and 5  are cross-sectional views as viewed from a lateral direction of the retaining member  8  in the first embodiment. The retaining member  8  includes a sleeve  14  and a buffer member (shock-absorbing material)  17 . The sleeve  14  includes a flange  14   a  at one end of the sleeve  14 . The buffer member  17  is formed in a cylindrical-tube shape and is attached to an outer circumference of the sleeve  14 . The buffer member  17  is, for example, made of rubber or elastomer. The buffer member  17  includes a small-diameter portion  17   a  at an axially-central portion of the buffer member  17 . The bracket portion  2   a  of the relay  2  is fitted into the small-diameter portion  17   a . The retaining member  8  is fixed to the mounting surface  13  by a stud bolt  15  and a nut  16 . The stud bolt  15  is fixed to the mounting surface  13  by welding or the like. The relay  2  is supported in a floating state through the buffer members  17  by the mounting surface  13 . Therefore, when the relay  2  operates, a vibration of the relay  2  which is transmitted to the mounting surface  13  is reduced. 
         [0032]    The base plate  6  is formed with through-holes  18  and cutouts  20  whose locations correspond respectively to the locations of the retaining members  8 . The through-holes  18  and the cutouts  20  penetrate through the base plate  6  in the Z-axis direction. The buffer member  17  of each retaining member  8  passes through the through-hole  18  or the cutout  20  and reaches the mounting surface  13 . In detail, as shown in  FIG. 4 , the cutout  20  corresponding to the retaining member  8 A is formed in each of the pair of side edges  6   b  of the base plate  6  which are parallel to Y-axis. Moreover, as shown in  FIG. 5 , the through-holes  18  respectively corresponding to the retaining members  8 B are formed in a middle portion of the base plate  6  with respect to a longitudinal direction of the base plate  6 . 
         [0033]    Since the base plate  6  is latched (or caught) through the latching members  9  by the relays  2 , a projection-surface portion  19  (see  FIG. 4 ) of the base plate  6  which is obtained by projecting the relay  2  on the base plate  6  in the Z-axis direction can be entirely formed as an opening of the base plate  6  so that the area of the base plate  6  is largely reduced. However, in this first embodiment, each of the through-holes  18  and the cutouts  20  has a minimum size necessary to pass the retaining member  8  therethrough in order to avoid an excessive reduction in strength and rigidity of the base plate  6 . 
         [0034]      FIG. 6  is a view showing a second embodiment according to the present invention. In the second embodiment, the layout of the first embodiment is modified such that the relays  2  are supported through the retaining members  8  by the mounting surface  13  without forming the above-mentioned through-hole  18  or cutout  20  in the base plate  6 . 
         [0035]    A power shut-off unit  1  in the second embodiment includes two relays  2  in the same manner as in the first embodiment. These two relays  2  are arranged along the same straight line such that longitudinal directions of the two relays  2  accord with (are identical with) the X-axis direction. One of the two relays  2  faces in a direction opposite to a facing direction of another of the two relays  2 . That is, the two relays  2  have postures opposite to each other so that the connection terminals  21  of the two relays  2  face in opposed outward directions. Between the two relays  2 , the resistor  7 A and the harness connector portions  7 B are disposed as the auxiliary electronic components  7 . (A longitudinal line of) The resistor  7 A formed in a long-and-thin shape is arranged along the same straight line together with the relays  2 . 
         [0036]    In this second embodiment, the base plate  6  is formed in a rectangular shape having a minimum width (dimension in the Y-axis direction) necessary to dispose the two relays  2  in series with each other as mentioned above. 
         [0037]    Each relay  2  includes a pair of bracket portions  2   a  in the same manner as in the first embodiment. Each bracket portion  2   a  holds the retaining member  8 . Each bracket portion  2   a  protrudes outwardly from the straight side edge  6   a  of the base plate  6  which is parallel to X-axis. Accordingly, each retaining member  8  does not interfere with the side edge  6   a  of the base plate  6  and is located outside the base plate  6 . Thus, each relay  2  is supported by the mounting surface  13  through the two retaining members  8  ( 8 A and  8 B) arranged outside the base plate  6 . 
         [0038]    The base plate  6  is connected with the relays  2  by the three latching members  9  provided at three spots, in the same manner as in the first embodiment. The latching member  9 A located at one end portion of one of the two relays  2  is symmetrical to the latching member  9 A located at one end portion of another of the two relays  2 . Hence, the base plate  6  is reliably supported by the two relays  2 . 
         [0039]    In the second embodiment, the base plate  6  does not include the through-hole  18  or the cutout  20 . Accordingly, the second embodiment is advantageous in strength of the base plate  6 , so that the base plate  6  can be made thinner. 
         [0040]    According to the present invention, alternatively, the structure in which the through-hole  18  or the cutout  20  is not provided as shown in  FIG. 6  can be appropriately combined with the structure in which the through-hole  18  and/or the cutout  20  are provided as shown in  FIG. 2 . 
         [0041]    Although the invention has been explained above with reference to the preferred embodiments of the invention, the invention is not limited to the embodiments described above. The above-described embodiments can be varied or modified as needed.