Patent Publication Number: US-2022234456-A1

Title: Hybrid electric vehicle

Description:
TECHNICAL FIELD 
     The present invention relates to a hybrid electric vehicle. 
     BACKGROUND ART 
     A Patent Literature 1 listed below discloses first and second motor-generators and an inverter of a hybrid electric vehicle. The first and second motor-generators are arranged in close proximity to each other so that their rotation axes are parallel. The first motor-generator mainly generates electricity from an output of an internal combustion engine. The second motor-generator mainly drives drive wheels of the vehicle. In addition, the inverter is also located in close proximity to the generator and the motor-generator. The generator and the motor-generator are electrically connected with the inverter by wiring harnesses, respectively. 
     CITATION LIST 
     Prior-Art Literature 
     Patent Literature 1: Japanese Granted Patent Publication No. 3843702 
     SUMMARY OF INVENTION 
     However, the wiring harness connecting the first motor-generator to the inverter is thick, short, and routed straight because it is for high-voltage AC three-phase power. For this reason, vibrations of the internal combustion engine input to the first motor-generator are transmitted to the wiring harness through a rotor and bearings of the first motor-generator. Furthermore, the wiring harness, which is short and routed straight, does not flex, so that it transmits the vibrations to the inverter. Thus, since the vibrations of the internal combustion engine are transmitted to the inverter, components of the inverter are required to be resistant to the vibrations. This results in a larger size of the inverter. 
     Therefore, it is an object of the present invention to provide a hybrid electric vehicle capable of suitably suppressing transmission of vibrations of an internal combustion engine to an inverter. 
     A hybrid electric vehicle according to an aspect of the present invention includes a generator mechanically connected with an internal combustion engine, and a motor-generator mechanically connected with drive wheels. The generator is electrically connected with an inverter by a wiring harness. A generator opening thorough which one end of the wiring harness is inserted is opened on a housing of the generator. An inverter opening thorough which another end of the wiring harness is inserted is opened on a housing of the inverter. The one end of the wiring harness is led out from the inverter opening in a first direction toward the generator. The other end of the wiring harness is led out from the generator opening in a second direction that is different from the first direction. The inverter opening is set off with respect to the generator opening in the second direction, and at least a portion of the wiring harness extends between the generator housing and the inverter housing. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configurational diagram of a hybrid electric vehicle according to an embodiment. 
         FIG. 2  is a front view showing a generator and an inverter in the hybrid electric vehicle. 
         FIG. 3  is a cross-sectional view taken along a line show in  FIG. 2 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a hybrid electric vehicle according to an embodiment will be explained with reference to  FIG. 1  to  FIG. 3 . 
     As shown in  FIG. 1  and  FIG. 2 , the hybrid electric vehicle (HEV)  1  according to the present embodiment is equipped with an internal combustion engine (ICE)  2 , a generator  3 , a motor-generator (MG)  4 , and an inverter  5  in an engine compartment of a front section of the vehicle. The generator  3  is mechanically connected with the ICE  2  with a gearbox  6  interposed therebetween. The MG  4  is mechanically connected with driving wheels (front wheels)  7  with the gearbox  6  interposed therebetween. The inverter  5  is electrically connected with both the generator  3  and the MG  4 . The inverter  5  is also electrically connected with a high-voltage battery  8 . Although not shown in the drawings, the HEV  1  is also equipped with a low-voltage (12V) battery for auxiliary devices. The low-voltage battery is electrically connected with the high-voltage battery  8  through a DC/DC converter built in the inverter  5 . The output from the DC/DC converter charges the low-voltage battery and is supplied directly to the auxiliary devices. 
     The HEV  1  according to the present embodiment adopts a series hybrid system, and the output (driving force) of the ICE  2  is not transmitted to the drive wheels  7 , but to the generator  3  via a speed-increasing gear set in the gearbox  6 . In other words, the generator  3  is mechanically connected with the ICE  2 . The electricity generated by the generator  3  is supplied to the MG  4  or (and) the high-voltage battery  8  via the inverter  5 . The electricity stored in the high-voltage battery  8  can be also supplied to the MG  4 . The ICE  2  in the present embodiment does not drive the HEV  1  with its output, but is used only for generating electricity. Therefore, the ICE  2  functions as part of the power generation system. 
     The output (driving force) of the MG  4  is transmitted to the drive wheels  7  through a reduction gear set in the gearbox  6  and drive shafts. In other words, MG  4  is mechanically connected with the drive wheels  7 . Furthermore, the electricity regenerated by the MG  4  during deceleration of the HEV  1  can be also supplied to the high-voltage battery  8  via the inverter  5 . As explained above, the gearbox  6  houses the speed-increasing gear set and the reduction gear set, but there is no gear meshing between them. 
     Next, with reference to  FIG. 2  and  FIG. 3 , the generator  3 , the MG  4  and the inverter  5 , as well as a wiring harness (hereinafter referred to simply as the harness)  9  that electrically connects the generator  3  to the inverter  5 .  FIG. 2  shows the generator  3  and inverter  5  as seen from the front of the vehicle.  FIG. 2  also shows the gearbox  6 , and P 1  in the figure is a fastening plane between the ICE  2  and the gearbox  6  and P 2  in the figure is a fastening plane between the gearbox  6  and the generator  3 . The fastening surface P 2  is also a fastening plane between the gearbox  6  and the MG  4 . The MG  4  is located at the back of the generator  3  (in  FIG. 2 ).  FIG. 3  is a cross-sectional view taken along a line III-III shown in  FIG. 2 . The inverter  5  is located above the generator  3  and the MG  4 , in close proximity to them. 
     A housing  3 H of the generator  3  (a generator housing) is made of aluminum alloy and comprised of a cylindrical main body  3 C and an end cap  3 B that has a shape formed by integrating a cylinder and a box together. The main body  3 C and the end cap  3 B are rigidly attached to each other by bolts. The main body  3 C is also rigidly attached to the gearbox  6  by bolts. A stator and a rotor of the generator  3  are built in the generator housing  3 H. The generator housing  3 H rotatably holds a rotary shaft  3 S of the rotor via bearings. One end of the rotary shaft  3 S extends into the inside of the gearbox  6 , and the rotor is rotated by the above-mentioned speed-increasing gear set. 
     The generator housing  3 H basically has a cylindrical shape, but its left-side portion (on the right side in  FIG. 2  seen from the front of the HEV  1 : on the opposite side to the gearbox  6 ) has a shape such that a cube is protruded from the cylinder to form a terminal box  3 T. The terminal box  3 T is protruded toward the inverter  5 . Therefore, a space is formed between a right-side portion (on a left side in  FIG. 2 ) of the generator  3  and the inverter  5 . Terminals three connected to stator coils are arranged in the terminal box  3 T. Inside the terminal box  3 T, terminals on one end of the harness  9  are electrically connected to terminals of the generator  3 . On the outer surface of the terminal box  3 T facing the gearbox  6 , a generator opening  3 O is opened for leading the one end of the harness  9  out of the generator housing  3 H. In other words, the one end of the harness  9  is inserted through the generator opening  3 O. Since the generator  3  is a high-voltage three-phase AC generator, the harness  9  is a bundle of plural thick electric wires. 
     A housing  4 H of the MG  4  (an MG housing) is also made of aluminum alloy and has a cylindrical shape. But a flange is formed on at an end of its right-side portion (on the left side in  FIG. 2 ) of the MG housing  4 H for being fastened with the gearbox  6 . The MG housing  4 H is rigidly connected to the gearbox  6  by bolts at this flange. In addition, a portion (a lower housing  5 L) of an after-explained housing  5 H of the inverter  5  (an inverter housing) is monolithically formed at this flange. A stator and a rotor of the MG  4  are built inside the MG housing  4 H. The MG housing  4 H holds a rotary shaft of the rotor rotatably via bearings. One end of the rotary shaft is extended into the gearbox  6  to rotate drive shafts through the above-mentioned speed-increasing gear set. A connecting portion of the gearbox  6 , which is connected with the drive shaft of the right front wheel  7 , is shown on the left side of  FIG. 2 . This connecting portion is located on a rear side of the vehicle with respect to the ICE  2 . 
     An inverter housing  5 H is also made of aluminum alloy and has a box shape. The inverter housing  5 H is comprised of an upper housing  5 U and a lower housing  5 L. The upper housing  5 U and the lower housing  5 L are rigidly connected to each other by bolts. In other words, the inverter housing  5 H is rigidly fixed with the MG housing  4 H. Inside the inverter housing  5 H, electronic components such as a power module  5 G for the generator  3  (a generator power module), a power module  5 M for the MG  4  (an MG power module) and a smoothing capacitor  5 C are stored. The generator power module  5 G is electrically connected with the generator  3  via the harness  9 . The MG power module  5 M is also electrically connected to the MG  4 . Both the generator power module  5 G and the MG power module  5 M are electrically connected to the smoothing capacitor  5 C. 
     The smoothing capacitor  5 C is located closer to the MG  4  than the generator power module  5 G and the MG power module  5 M. More specifically, the smoothing capacitor  5 C is fixed on an inner bottom surface of the inverter housing  5 H. The generator power module  5 G and the MG power module  5 M are arranged side by side on an opposite side to the smoothing capacitor  5 C with respect to the MG  4 . More specifically, the generator power module  5 G and the MG power module  5 M are fixed on an inner top surface of the inverter housing  5 H. Since the smoothing capacitor  5 C is used by both the generator power module  5 G and the MG power module  5 M, it is placed in the center between the two in consideration of their wiring lengths. 
     A portion of the inverter housing  5 H closest to the gearbox  6  (i.e. the ICE  2 ) and farthest from the MG  4  is protruded outward (upward), and an inverter opening  5 O is opened in this protruded part for leading the other end of the harness  9  out of the inverter housing  5 H. That is, the other end of the harness  9  is inserted through the inverter opening  5 O. In other words, the inverter opening  5 O is located at a position on the outer surface of the inverter housing  5 H that is closest to the ICE  2  and that is on a furthest side of the inverter housing  5 H from the MG  4 . 
     Note that the right-side portion (on the left side in  FIG. 2 ) of the generator housing  3 H is fixed to the MG housing  4 H (the lower housing  5 L) by a first bracket  10 , and the left-side portion (on the left side in  FIG. 2 ) thereof is fixed to the MG housing  4 H by a second bracket  11 . The first bracket  10  and the second bracket  11  are made of steel, which is more flexible as metal than aluminum alloy, and are plate materials that can flex slightly. (Vibration durability and damping characteristics of aluminum-based metal [aluminum alloy] is inferior to those of iron-based metal [steel].) Therefore, the first bracket  10  and the second bracket  11  damp vibrations of the generator  3  and thereby hardly transmit them to the MG  4 . 
     Although the harness  9  extends between the inverter opening  5 O and the generator opening  3 O, a lead-out direction of its one end from the inverter opening  5 O is defined as a first direction D 1  (see  FIG. 2  and  FIG. 3 ) and a lead-out direction of its other end from the generator opening  3 O is defined as a second direction D 2  (see  FIG. 2 ). The first direction D 1  is the direction directing from the inverter opening  5 O toward the generator  3 . The second direction D 2  is parallel to an axial direction DS (see  FIG. 2 ) of the rotary shaft  3 S of the generator  3  in the present embodiment. In other words, the first direction D 1  and the second direction D 2  are different from each other. More specifically, in this embodiment, the first direction D 1  and the second direction D 2  are perpendicular to each other. Therefore, the harness  9  extending between the inverter opening  5 O and the generator opening  3 O is necessarily curved and does not extend straight. Since the curved portion of the harness  9  can flex, it becomes possible to deter transmission of vibrations from the generator  3  to the inverter  5  (to absorb the vibrations). 
     Further, as shown in  FIG. 2 , the inverter opening  5 O is set off with respect to the generator opening  3 O opened on the terminal box  3 T in the second direction D 2 . In other words, the position of the inverter opening  5 O is different from the position of the generator opening  3 O along the second direction D 2 . That is, the inverter opening  5 O and the generator opening  3 O are not on the same plane. Therefore, the harness  9  can be made longer, and the transmission of vibrations from the generator  3  to the inverter  5  can be deterred more effectively. In addition, by setting them off from each other, the curvature radius of the harness  9  can be made large. Furthermore, at least a portion of the harness  9  extends through a space between the generator  3  and the inverter  5 . Therefore, it is preferable even when the harness  9  is long, because this space can be used effectively. By effectively utilizing this space, the height of the hybrid system unit can be reduced and thereby it can be downsized. 
     Note that, when the first direction D 1  and the second direction D 2  are different from each other even if the second direction D 2  is not parallel to the axial direction DS, the harness  9  inevitably curves. When the harness  9  curves, the above-mentioned vibrations can be absorbed. However, considering the first direction D 1  toward the generator  3  and the protruding direction of the terminal box  3 T, on which the generator opening  3 O is formed, toward the inverter  5 , it is preferable in view of smooth routing of the curved harness  9  that the second direction D 2  is parallel to the axial direction DS. Especially in a case where the harness  9  is made long due to the offset of the inverter opening  5 O with respect to the generator opening  3 O in the second direction D 2 , it is preferable because the space between the generator  3  and the inverter  5  can be effectively utilized. In this embodiment, it is further preferable to locate the terminal box  3 T, on which the generator opening  3 O is formed, on the farthest side from the inverter opening  5 O along the axial direction DS, because the harness  9  can be made as long as possible. 
     In addition, the inverter opening  5 O is opened on the inverter housing  5 H at its outward (upward) protruding portion furthest from the MG  4 . This allows the harness  9  to be made longer and the curvature radius of the flexure of the harness  9  can be made large. Since the harness  9  is thick as explained above and thereby is difficult to be flexed, its large curvature radius facilitates the routing of the harness  9 . Further, its large curvature radius does not put excessive stresses on the harness  9 . 
     The above-mentioned routing of the harness  9  relates to the positional relationship viewed from the front of the vehicle. Further in the present embodiment, as shown in  FIG. 3 , the harness  9  is routed such that the smoothing capacitor  5 C does not overlap with the harness  9  when viewed from the axial direction DS. Since the smoothing capacitor  5 C does not overlap with the harness  9 , the inverter opening  5 O and the generator opening  3 O are arranged in close proximity along the first direction D 1  when viewed from the axial direction DS, that is, the inverter housing  5 H and the generator housing  3 H (the terminal box  3 T) can be arranged in close proximity. Further in the present configuration, the bottom of the inverter housing  5 H is deformed to avoid the terminal box  3 T, and this configuration can be brought precisely because the both don&#39;t overlap with each other. This configuration allows the height of the hybrid system unit to be reduced, and thereby the system can be downsized. Note that, even if the inverter housing  5 H and the generator housing  3 H (the terminal box  3 T) are placed in close proximity, the harness  9  is also routed in the second direction D 2 , and thereby the harness  9  can be made long by being curved to deter the transmission of the vibrations. 
     As described above, the HEV  1  in this embodiment adopts a series hybrid system. Therefore, the vibrations of the ICE  2  is transmitted to the rotary shaft  3 S of the generator  3 , which is mechanically connected to the ICE  2 . The vibrations are also transmitted to the generator housing  3 H and the stator in its inside through the bearings. Further, the vibrations are also transmitted to the harness  9  via the stator coils, but they are absorbed by the harness  9  as explained above. In the present embodiment, the generator housing  3 H is not rigidly connected to the MG housing  4 H, so that the above-mentioned vibrations are not directly transmitted to the MG housing  4 H. Therefore, the transmission of the vibrations of the ICE  2  to the inverter  5  can be suitably suppressed. As a result, the components of the inverter  5  are not required to have excessive vibration resistance. 
     According to the HEV  1  of the present embodiment, the first direction D 1  toward the generator (the lead-out direction of the harness  9  from the inverter opening  5 O) is different from the second direction D 2  (the lead-out direction of the harness  9  from the generator opening  3 O). Therefore, the harness  9  necessarily curves. In addition, the inverter opening  5 O is set off with respect to the generator opening  3 O in the second direction D 2 . Therefore, the harness  9  can be made longer. As the result, the harness  9  can absorb the vibrations of the ICE  2  and deter the transmission of the vibrations of the ICE  2  to the inverter  5 . Further, at least the portion of the harness  9  extends between the generator housing  3 H and the inverter housing  5 H. Therefore, even if the harness  9  is long, the space between the generator housing  3 H and the inverter housing  5 H can be utilized effectively, and thereby the height of the hybrid system unit can be reduced to make it downsized. 
     Here, the second direction D 2  is parallel to the axial direction DS of the rotary shaft  3 S of the generator  3 , and the generator opening  3 O is opened on the terminal box  3 T protruding toward the inverter  5 . The above-mentioned space between the generator housing  3 H and the inverter housing  5 H can be formed beside the terminal box  3 T, and the harness  9  can be smoothly led out from the generator housing  3 H to the space in the axial direction DS. Therefore, the harness  9  can be smoothly routed. Note that the first direction D 1  is the direction extending toward the generator  3 , and thereby it intersects the second direction D 2  (the axial direction DS). Thus, the harness  9  can smoothly flex from the first direction D 1  to the second direction D 2 . 
     In addition, the inverter opening  5 O is opened at a position on the outer surface of the inverter housing  5 H that is closest to the ICE  2 , and the terminal box  3 T is located at a position on the generator housing  3 H that is on the farthest side from the inverter opening  5 O along the axial direction DS. Therefore, the distance along the axial direction DS between the inverter opening  5 O and the generator opening  3 O formed in the terminal box  3 T can be as long as possible. As a result, the harness  9  can be made long and it can absorb the above-mentioned vibrations effectively. 
     Further, the inverter opening  5 O is located on the inverter housing  5 H at a position on the farthest side from the MG  4 , and thereby the harness  9  can be made long even along the first direction D 1  to absorb the above-mentioned vibrations more effectively. In addition, the curvature radius of the flexure of the harness  9  from the first direction D 1  to the second direction D 2  can be made large. A large curvature radius makes it easier to route the harness  9  and does not cause excessive stress on the harness  9 . 
     In the inverter housing  5 H, the generator power module  5 G and the MG power module  5 M are arranged side by side on the opposite side to the MG  4  with respect to the smoothing capacitor  5 C. In addition, the smoothing capacitor  5 C does not overlap with the harness  9  when viewed along the axial direction DS. In other words, the inverter housing  5 H and the generator housing  3 H (the terminal box  3 T) are arranged in close proximity along the first direction D 1 . Therefore, the height of the hybrid system unit can be reduced, and thereby the system can be downsized. 
     Note that the present invention is not limited to the embodiment described above. In the above embodiment, as shown in  FIG. 2 , the inverter opening  5 O is arranged on the side close to the ICE  2  and the generator opening  3 O is arranged on the side far from the ICE  2  (the inverter opening  5 O and the generator opening  3 O are opened toward the ICE  2 ). However, the inverter opening may be placed on the side far from the ICE and the generator opening may be placed close to the ICE (the inverter opening and the generator opening are opened in the opposite direction to the ICE). Also in this case, the harness  9  can be necessarily curved by making the first direction D 1  towards the generator  3  different from the second direction D 2 . Further, the hybrid system may be mounted at a position other than the front section of the vehicle. Furthermore, also the mounting orientation of the hybrid system is not limited to the orientation in the above embodiment. 
     REFERENCE SIGNS LIST 
     
         
           1  hybrid electric vehicle (HEV) 
           2  internal combustion engine (ICE) 
           3  generator 
           3 H generator housing 
           3 O generator opening 
           3 S rotary shaft 
           3 T terminal box 
           4  motor-generator (MG) 
           4 H MG housing 
           5  inverter 
           5 H inverter housing 
           5 O inverter opening 
           5 G generator power module 
           5 M MG power module 
           5 C smoothing capacitor 
           7  drive wheel 
           9  wiring harness 
         D 1  first direction 
         D 2  second direction 
         DS axial direction