Patent Publication Number: US-2023146854-A1

Title: Device attachment structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2021-181885 filed on Nov. 8, 2021, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The disclosure relates to a device attachment structure for attaching a power conversion device to a vehicle. 
     Power conversion devices, such as inverters, converters, and on-board chargers, are mounted in vehicles such as electric automobiles and hybrid automobiles (see Japanese Unexamined Patent Application Publications Nos. 2020-147207, 2016-49862, and 2013-86681). To reduce transmission of vibration from a power conversion device, such as an inverter, to a vehicle body, for example, a rubber bushing or the like is used to attach the power conversion device to a vehicle. 
     SUMMARY 
     An aspect of the disclosure provides a device attachment structure for attaching a power conversion device to a vehicle. The device attachment structure includes a vehicle member, a device member, a first bushing, a second bushing, a first fastener, and a second fastener. The vehicle member is provided on the vehicle and includes a first thread and a second thread. The device member is provided on the power conversion device and has a first through hole and a second through hole. The first bushing includes a first outer sleeve and a first inner sleeve. The first outer sleeve is fitted to the first through hole. The first inner sleeve is coupled to an inner periphery of the first outer sleeve with an elastic body provided between the first inner sleeve and the first outer sleeve. The second bushing includes a second outer sleeve and a second inner sleeve. The second outer sleeve is fitted to the second through hole. The second inner sleeve is coupled to an inner periphery of the second outer sleeve with an elastic body provided between the second inner sleeve and the second outer sleeve. The first fastener is attached to the first thread of the vehicle member and configured to fasten the first inner sleeve to the vehicle member. The second fastener is attached to the second thread of the vehicle member and configured to fasten the second inner sleeve to the vehicle member. The device member has a first surface that faces the vehicle member and a second surface that is opposite to the first surface. The first through hole in the device member has a large-diameter space that opens in the first surface and to which the first outer sleeve is fitted and a small-diameter space that opens in the second surface and through which the first inner sleeve passes. The second through hole in the device member has a large-diameter space that opens in the second surface and to which the second outer sleeve is fitted and a small-diameter space that opens in the first surface and through which the second inner sleeve passes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments and, together with the specification, serve to describe the principles of the disclosure. 
         FIG.  1    illustrates an example of a hybrid vehicle including a device attachment structure according to an embodiment of the disclosure; 
         FIG.  2    is a top view of a power train disposed in an engine room; 
         FIG.  3    is an enlarged view of a power conversion unit illustrated in  FIG.  2    and a region around the power conversion unit; 
         FIG.  4    illustrates the power conversion unit and the region around the power conversion unit viewed in a direction of arrow IV in  FIG.  2   ; 
         FIG.  5    is a sectional view of attachment mechanisms taken along line V-V in  FIG.  3   ; 
         FIG.  6    illustrates a procedure for attaching the power conversion unit to an engine bracket; 
         FIG.  7    illustrates the procedure for attaching the power conversion unit to the engine bracket; 
         FIG.  8    illustrates the procedure for attaching the power conversion unit to the engine bracket; 
         FIG.  9    is a sectional view of attachment mechanisms taken along line IX-IX in  FIG.  3   ; 
         FIG.  10    illustrates positions of the attachment mechanisms with which the power conversion unit is attached to an engine; 
         FIG.  11    illustrates a device attachment structure according to another embodiment of the disclosure; 
         FIG.  12    illustrates a device attachment structure according to another embodiment of the disclosure; and 
         FIG.  13    illustrates a device attachment structure according to another embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A power conversion device, such as an inverter, is heavy. Therefore, even when an attachment structure including a rubber bushing or the like is employed, the power conversion device is to be appropriately attached to a vehicle. In other words, the power conversion device is to be appropriately attached to the vehicle so that the power conversion device does not fall off the vehicle when a large force is applied thereto in case of, for example, a vehicle collision. 
     It is desirable to appropriately attach a power conversion device to a vehicle. 
     In the following, some embodiments of the disclosure are described in detail with reference to the accompanying drawings. Note that the following description is directed to illustrative examples of the disclosure and not to be construed as limiting to the disclosure. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting to the disclosure. Further, elements in the following example embodiments which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Throughout the present specification and the drawings, elements having substantially the same function and configuration are denoted with the same numerals to avoid any redundant description. 
     Vehicle Structure 
       FIG.  1    illustrates an example of a hybrid vehicle  11  including a device attachment structure  10  according to an embodiment of the disclosure. As illustrated in  FIG.  1   , the hybrid vehicle (vehicle)  11  includes a power train  14  including an engine  12  and a transmission  13 . The transmission  13  includes a motor generator MG and a front differential mechanism  16 . Front wheels  17  are coupled to the engine  12  and the motor generator MG by the front differential mechanism  16 . Rear wheels  21  are coupled to the engine  12  and the motor generator MG by a rear-wheel output shaft  18 , a propeller shaft  19 , and a rear differential mechanism  20 . The illustrated vehicle  11  is an all-wheel-drive vehicle. However, the vehicle  11  is not limited to this, and may be a front-wheel-drive vehicle or a rear-wheel-drive vehicle. 
     An intake manifold  22  that guides intake air is attached to the top of the engine  12 . A power conversion unit  23 , which serves as a power conversion device, is also attached to the top of the engine  12  at a position behind the intake manifold  22 . A battery  25 , such as a lithium ion battery, is coupled to the power conversion unit  23  by an electric power cable  24 . The power conversion unit  23  includes an inverter (not illustrated) that controls the state of energization of the motor generator MG and a boost converter (not illustrated) that boosts direct current power supplied from the battery  25 . When the motor generator MG is set to a power running state, the power conversion unit  23  converts direct current power supplied from the battery  25  into alternating current power, which is supplied to the motor generator MG. When the motor generator MG is set to a power generating state, the power conversion unit  23  converts alternating current power supplied from the motor generator MG into direct current power, which is supplied to the battery  25 . 
     Device Attachment Structure 
     An attachment structure (device attachment structure)  10  used to attach the power conversion unit  23  to the engine  12  will now be described.  FIG.  2    is a top view of the power train  14  disposed in an engine room  26 .  FIG.  3    is an enlarged view of the power conversion unit  23  illustrated in  FIG.  2    and a region around the power conversion unit  23 .  FIG.  4    illustrates the power conversion unit  23  and the region around the power conversion unit  23  viewed in a direction of arrow IV in  FIG.  2   . 
     As illustrated in  FIG.  2   , the intake manifold  22  and the power conversion unit  23  are attached to the top of the engine  12 . The intake manifold  22  includes a surge tank  27 . The surge tank  27  is disposed in front of the power conversion unit  23 . Four branches  28  extend from the surge tank  27  of the intake manifold  22 , and some of the branches  28  are disposed near both ends  23   a  and  23   b  of the power conversion unit  23 . As illustrated in  FIGS.  3  and  4   , an engine bracket (vehicle member)  31  is attached to the engine  12  mounted in the vehicle  11  with, for example, fastening bolts  30 . A device bracket (device member)  33  is attached to the power conversion unit  23  with, for example, fastening bolts  32 . The engine bracket  31  and the device bracket  33  are fastened together by using four attachment mechanisms  40  and  50  described below. Thus, the illustrated power conversion unit  23  is attached to the vehicle  11  by using the four attachment mechanisms  40  and  50 . 
       FIG.  5    is a sectional view of the attachment mechanisms  40  and  50  taken along line V-V in  FIG.  3   .  FIGS.  6  to  8    illustrate a procedure for attaching the power conversion unit  23  to the engine bracket  31 . As illustrated in  FIG.  6   , the device bracket  33  has a first through hole  41  and a second through hole  51  that extend through the device bracket  33  in a thickness direction. The first through hole  41  includes a large-diameter space  41   a  that opens in a lower surface (first surface)  33   a  of the device bracket  33  and a small-diameter space  41   b  that opens in an upper surface (second surface)  33   b  of the device bracket  33 . The second through hole  51  includes a large-diameter space  51   a  that opens in the upper surface  33   b  of the device bracket  33  and a small-diameter space  51   b  that opens in the lower surface  33   a  of the device bracket  33 . As illustrated in  FIG.  5   , the lower surface  33   a  of the device bracket  33  is a surface facing the engine bracket  31 , and the upper surface  33   b  of the device bracket  33  is a surface that is opposite to the lower surface  33   a.    
     As illustrated in  FIG.  6   , a first bushing  42  is press-fitted into the first through hole  41  in the device bracket  33  from below. The first bushing  42  includes a first outer sleeve  43 , a first inner sleeve  44  disposed inside the first outer sleeve  43 , and an elastic body  45  made of rubber that couples the first outer sleeve  43  and the first inner sleeve  44 . As illustrated in  FIG.  7   , the first outer sleeve  43  is fitted to the large-diameter space  41   a , and the first inner sleeve  44  passes through the small-diameter space  41   b . As illustrated in  FIG.  6   , a second bushing  52  is press-fitted into the second through hole  51  in the device bracket  33  from below. The second bushing  52  includes a second outer sleeve  53 , a second inner sleeve  54  disposed inside the second outer sleeve  53 , and an elastic body  55  made of rubber that couples the second outer sleeve  53  and the second inner sleeve  54 . As illustrated in  FIG.  7   , the second outer sleeve  53  is fitted to the large-diameter space  51   a , and the second inner sleeve  54  passes through the small-diameter space  51   b . After the first bushing  42  and the second bushing  52  are attached to the device bracket  33  in this manner, the device bracket  33  is fixed to the power conversion unit  23  by using the fastening bolts  32 , as illustrated in  FIG.  7   . 
     As illustrated in  FIG.  8   , a nut  47  having an internal thread (first thread)  46  and a nut  57  having an internal thread (second thread)  56  are welded to the engine bracket  31  attached to the engine  12 . Since the nuts  47  and  57  are fixed to the engine bracket  31  by welding, the engine bracket  31  is provided with the internal threads  46  and  56 . The device bracket  33  of the power conversion unit  23  is placed on the engine bracket  31  such that the first through hole  41  faces the internal thread  46  and that the second through hole  51  faces the internal thread  56 . 
     Then, a first fastening bolt (first fastener, bolt)  48  is inserted through the first inner sleeve  44  from above, and an external thread  48   a  of the first fastening bolt  48  is screwed into the internal thread  46 . Thus, the first inner sleeve  44  of the first bushing  42  is fastened to the engine bracket  31  by the first fastening bolt  48 . Similarly, a second fastening bolt (second fastener, bolt)  58  is inserted through the second inner sleeve  54  from above, and an external thread  58   a  of the second fastening bolt  58  is screwed into the internal thread  56 . Thus, the second inner sleeve  54  of the second bushing  52  is fastened to the engine bracket  31  by the second fastening bolt  58 . A first washer  49  is provided between a head  48   b  of the first fastening bolt  48  and the first inner sleeve  44 . A second washer  59  is provided between a head  58   b  of the second fastening bolt  58  and the second inner sleeve  54 . 
     Thus, one end  23   a  of the power conversion unit  23  in a vehicle width direction is supported by the first attachment mechanism  40  constituted by the internal thread  46 , the first through hole  41 , the first bushing  42 , and the first fastening bolt  48 , and is also supported by the second attachment mechanism  50  constituted by the internal thread  56 , the second through hole  51 , the second bushing  52 , and the second fastening bolt  58 . In a region near the end  23   a  of the power conversion unit  23 , the first attachment mechanism  40  is disposed closer to the rear of the vehicle than the second attachment mechanism  50 .  FIG.  9    is a sectional view of the attachment mechanisms  40  and  50  taken along line IX-IX in  FIG.  3   . As illustrated in  FIG.  9   , the other end  23   b  of the power conversion unit  23  in the vehicle width direction is also supported by the first attachment mechanism  40  constituted by the internal thread  46 , the first through hole  41 , the first bushing  42 , and the first fastening bolt  48  and by the second attachment mechanism  50  constituted by the internal thread  56 , the second through hole  51 , the second bushing  52 , and the second fastening bolt  58 . In a region near the end  23   b  of the power conversion unit  23 , the first attachment mechanism  40  is disposed closer to the front of the vehicle than the second attachment mechanism  50 . 
     As described above, the engine bracket  31  provided on the vehicle  11  and the device bracket  33  provided on the power conversion unit  23  are coupled to each other by the four attachment mechanisms  40  and  50 . In other words, the engine bracket  31  and the device bracket  33  are coupled to each other with the elastic bodies  45  and  55  of the first and second bushings  42  and  52  provided therebetween. When the elastic bodies  45  and  55  are provided between the engine  12  and the power conversion unit  23 , transmission of vibration between the engine  12  and the power conversion unit  23  can be reduced. Accordingly, noise and vibration transmitted from the power conversion unit  23  to, for example, a vehicle body  60  through the engine  12  can be reduced. In addition, the power conversion unit  23  can be protected from engine vibration. 
     The device bracket  33  can be attached to the engine bracket  31  by screwing the fastening bolts  48  and  58  from above the device bracket  33 . In addition, the device bracket  33  can be removed from the engine bracket  31  by loosening the fastening bolts  48  and  58  from above the device bracket  33 . Accordingly, the device bracket  33  can be easily attached to and removed from the engine bracket  31  by an operator. Thus, attachment and removal of the power conversion unit  23  to and from the engine room  26  can be facilitated. As illustrated in  FIG.  2   , the branches  28  of the intake manifold  22  are disposed near the ends  23   a  and  23   b  of the power conversion unit  23 . Therefore, it is difficult to bring a tool closer to the power conversion unit  23  in the vehicle width direction. Since the fastening bolts  48  and  58  are attached and removed from above the device bracket  33  as described above, the power conversion unit  23  can be very easily attached or removed. 
     Prevention of Falling of Power Conversion Unit 
     As described above, the first bushing  42  and the second bushing  52  are press-fitted to the device bracket  33  of the power conversion unit  23 . Thus, the device bracket  33  is retained by the fitting force of the first outer sleeve  43  and the second outer sleeve  53 . Even when a large force is applied to the device bracket  33  in case of, for example, a vehicle collision, falling of the device bracket  33 , that is, falling of the power conversion unit  23 , is to be prevented. Accordingly, in the device attachment structure  10  of the present embodiment, the first bushing  42  is press-fitted through the lower surface  33   a  of the device bracket  33 , and the second bushing  52  is press-fitted through the upper surface  33   b  of the device bracket  33 . Thus, the direction in which the first bushing  42  is pulled out and the direction in which the second bushing  52  is pulled out differ from each other, so that the first bushing  42  and the second bushing  52  can be prevented from falling together. 
     When the device bracket  33  is pushed upward as indicated by arrow a 1  in  FIGS.  5  and  9    by an input in a vehicle collision, the second bushing  52  is not pulled out of the device bracket  33  and remains fitted to the device bracket  33 . When the device bracket  33  is pushed downward as indicated by arrow a 2  in  FIGS.  5  and  9    by an input in a vehicle collision, the first bushing  42  is not pulled out of the device bracket  33  and remains fitted to the device bracket  33 . Therefore, even when the power conversion unit  23  is violently shaken by inertial force in a vehicle collision, the first bushing  42  and the second bushing  52  do not fall off the device bracket  33  together. Accordingly, falling of the device bracket  33 , that is, falling of the power conversion unit  23 , can be prevented. 
       FIG.  10    illustrates the positions of the attachment mechanisms with which the power conversion unit  23  is attached to the engine  12 . In  FIG.  10   , bolt heads of the first attachment mechanisms  40  which each include the first bushing  42  are marked “1”, and bolt heads of the second attachment mechanisms  50  which each include the second bushing  52  are marked “2”. As illustrated in  FIG.  10   , the engine bracket  31  and the device bracket  33  include a first corner X 1  and a second corner X 2  on one diagonal, and a third corner X 3  and a fourth corner X 4  on the other diagonal. The first attachment mechanisms  40  which each include the first bushing  42  are provided at the first corner X 1  and the second corner X 2 . The second attachment mechanisms  50  which each include the second bushing  52  are provided at the third corner X 3  and the fourth corner X 4 . In other words, the two first attachment mechanisms  40  are disposed at one pair of diagonal corners, and the two second attachment mechanisms  50  are disposed at other pair of diagonal corners. 
     When the first attachment mechanisms  40  and the second attachment mechanisms  50  are disposed as described above, the first bushings  42  and the second bushings  52  can be prevented from falling off the device bracket  33  even when force is applied to the power conversion unit  23  in various directions as indicated by arrows a. Accordingly, falling of the device bracket  33 , that is, falling of the power conversion unit  23 , can be prevented. In other words, the first bushings  42  and the second bushings  52  can be prevented from falling off the device bracket  33  both when the ends  23   a  and  23   b  of the power conversion unit  23  in the vehicle width direction move vertically as indicated by signs β 1  and β 2  and when ends  23   c  and  23   d  of the power conversion unit  23  in a front-rear direction move vertically as indicated by signs β 3  and β 4 . Accordingly, falling of the device bracket  33 , that is, falling of the power conversion unit  23 , can be prevented. 
     As described above, the first washer  49  is provided between the head  48   b  of the first fastening bolt  48  and the first inner sleeve  44 , and the second washer  59  is provided between the head  58   b  of the second fastening bolt  58  and the second inner sleeve  54 . Therefore, when the first fastening bolt  48  is fastened, rotational force transmitted from the first fastening bolt  48  to the first outer sleeve  43  through the first inner sleeve  44  can be reduced, so that loosening of the first outer sleeve  43  that is fitted can be prevented. Similarly, when the second fastening bolt  58  is fastened, rotational force transmitted from the second fastening bolt  58  to the second outer sleeve  53  through the second inner sleeve  54  can be reduced, so that loosening of the second outer sleeve  53  that is fitted can be prevented. This also contributes to prevention of falling of the first and second bushings  42  and  52 . 
     Another Embodiment 1 
     According to the above description, two first attachment mechanisms  40  and two second attachment mechanisms  50  are used to attach the power conversion unit  23  to the engine  12 . However, the structure is not limited to this. The power conversion unit  23  may be attached to the engine  12  by using one first attachment mechanism  40  and one second attachment mechanism  50 . Alternatively, the power conversion unit  23  may be attached to the engine  12  by using one first attachment mechanism  40  and more than one second attachment mechanisms  50 , or by using more than one first attachment mechanisms  40  and one second attachment mechanism  50 . Alternatively, the power conversion unit  23  may be attached to the engine  12  by using more than one first attachment mechanisms  40  and more than one second attachment mechanisms  50 . 
       FIG.  11    illustrates a device attachment structure  70  according to another embodiment of the disclosure. As illustrated in  FIG.  11   , a first attachment mechanism  40  and a second attachment mechanism  50  are provided at one end  23   a  of a power conversion unit  23  in a vehicle width direction. Another first attachment mechanism  40  is provided at the other end  23   b  of the power conversion unit  23  in the vehicle width direction. Also when a device bracket  33  is attached by using two first attachment mechanisms  40  and one second attachment mechanism  50  as in this example, first bushings  42  and a second bushing  52  can be prevented from falling off a device bracket  33  together. Accordingly, falling of the device bracket  33 , that is, falling of the power conversion unit  23 , can be prevented. Here, the device bracket  33  may instead be attached by using one first attachment mechanism  40  and two second attachment mechanisms  50 . 
     Another Embodiment 2 
     According to the above description, the power conversion unit  23  is attached to the engine  12 . However, the structure is not limited to this, and the power conversion unit  23  may be attached to other vehicle members.  FIG.  12    illustrates a device attachment structure  80  according to another embodiment of the disclosure. In  FIG.  12   , the device attachment structure  80  is disposed in an engine room  26 . As illustrated in  FIG.  12   , a vehicle body bracket (vehicle member)  81  that is fixed to a vehicle body  60  is provided in the engine room  26 , and a device bracket  33  is attached to a power conversion unit  23 . The vehicle body bracket  81  and the device bracket  33  are fastened together by using first attachment mechanisms  40  and second attachment mechanisms  50 . Also when the power conversion unit  23  is attached to the vehicle body  60  as in this example, first and second bushings  42  and  52  are prevented from falling off the device bracket  33  together. Accordingly, falling of the device bracket  33 , that is, falling of the power conversion unit  23 , can be prevented. 
     Another Embodiment 3 
     In the example illustrated in  FIG.  5   , the fastening bolts  48  and  58  are respectively screwed into the internal threads  46  and  56  in an engine bracket  31 . However, the structure is not limited to this.  FIG.  13    illustrates a device attachment structure  90  according to another embodiment of the disclosure.  FIG.  13    illustrates a region similar to that illustrated in  FIG.  5   . As illustrated in  FIG.  13   , a stud bolt  92  having an external thread (first thread)  91  and a stud bolt  94  having an external thread (second thread)  93  are fixed to the engine bracket  31 . Since the stud bolts  92  and  94  are fixed to the engine bracket  31 , the engine bracket  31  is provided with the external threads  91  and  93 . A device bracket  33  of a power conversion unit  23  is placed on the above-described engine bracket  31  such that the stud bolt  92  is inserted through a first through hole  41  and that the stud bolt  94  is inserted through a second through hole  51 . 
     Then, an internal thread  96  of a first fastening nut (first fastener)  95  is screwed onto the external thread  91  of the stud bolt  92 . Thus, a first inner sleeve  44  of a first bushing  42  is fastened to the engine bracket  31  by the first fastening nut  95 . Similarly, an internal thread  98  of a second fastening nut (second fastener)  97  is screwed onto the external thread  93  of the stud bolt  94 . Thus, a second inner sleeve  54  of a second bushing  52  is fastened to the engine bracket  31  by the second fastening nut  97 . A first washer  49  is provided between the first fastening nut  95  and the first inner sleeve  44 . A second washer  59  is provided between the second fastening nut  97  and the second inner sleeve  54 . Also when the stud bolts  92  and  94  are provided on the engine bracket  31  and the fastening nuts  95  and  97  are screwed onto the stud bolts  92  and  94  as in this example, a function similar to that of the above-described device attachment structure  10  can be obtained. 
     The disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the disclosure. According to the above description, the device attachment structures  10 ,  70 ,  80 , and  90  are applied to the hybrid vehicle  11  including the engine  12 . However, the structure is not limited to this, and the device attachment structures  10 ,  70 ,  80 , and  90  may be applied to a vehicle having no engine  12 , such as an electric automobile. In addition, according to the above description, the power conversion unit  23  is attached to the longitudinal engine  12 . However, the structure is not limited to this, and the power conversion unit  23  may be attached to a transverse engine. Alternatively, the power conversion unit  23  may be attached to the transmission  13 . 
     According to the above description, the power conversion unit  23  in which an inverter and a converter are integrated serves as the power conversion device. However, the structure is not limited to this, and the power conversion device may be an inverter. Alternatively, the power conversion device may be a converter or an on-board charger. In the example illustrated in  FIG.  8   , the nuts  47  and  57  that respectively have the internal threads  46  and  56  are welded to the device bracket  33 , which is a device member. However, the structure is not limited to this, and the internal threads  46  and  56  may be formed in the base material of the device bracket  33 . 
     A device attachment structure according to an embodiment includes a device member provided on a power conversion device and having a first through hole and a second through hole. The first through hole in the device member includes a large-diameter space that opens in a first surface and to which a first outer sleeve is fitted. The second through hole in the device member includes a large-diameter space that opens in a second surface and to which a second outer sleeve is fitted. Accordingly, the power conversion device can be appropriately attached to a vehicle.