Patent Publication Number: US-2023163656-A1

Title: Vehicle drive device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 
     2021-189346 filed on Nov. 22, 2021, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a vehicle drive device. 
     2. Description of Related Art 
     Battery electric vehicles and hybrid electric vehicles are equipped with a drive device provided with a rotary electric machine such as a motor or a generator serving as a drive source. The rotary electric machine is housed in a case and is covered with a cover (see, for example, Japanese Unexamined Patent Application Publication No. 2020-54073 (JP 2020-54073 A)). 
     SUMMARY 
     The cover is formed to be thin in order to make it easy to mount the drive device on the vehicle and to reduce the weight of the vehicle. Thus, the cover is likely to generate vibration and noise due to a rotation of the rotary electric machine, which may reduce a noise vibration (NV) performance of the vehicle. 
     Further, when the drive device is arranged near a side member of the vehicle, for example, there is a possibility that the side member is damaged and comes into contact with the cover when the vehicle collides. In this case, there is possibility that a fragile portion of the cover is damaged and that not only the fragments come into contact with the coil of the rotary electric machine during energization, but also the coil are exposed to the outside from the damaged portion. 
     The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a vehicle drive device capable of improving an NV performance and safety of a vehicle. 
     A vehicle drive device of the present disclosure includes: a rotary electric machine including a coil end around a rotation shaft on an end face in a rotation shaft direction; a cover that covers the end face; and a plate-shaped member that is fixed to a back surface of the cover and that faces at least a part of the coil end, in which the cover includes one or more first ribs extending outward from the rotation shaft in a front view of the end face, and in which the plate-shaped member extends along a direction orthogonal to a direction in which the one or more first ribs extend. 
     In the above configuration, there may be a plurality of the first ribs, and the plate-shaped member may be provided so as to bridge over the first ribs in a front view of the cover. 
     In the above configuration, the plate-shaped member may be screwed to the back surface. 
     In the above configuration, a holding portion for holding one end of the rotation shaft may be provided on the back surface, and the plate-shaped member may be fixed to the back surface at an end portion on the holding portion side. 
     In the above configuration, the cover may include a bending portion that bends toward the coil end side, and a gap between an outer peripheral edge of the plate-shaped member and the bending portion may be smaller than a size of a finger. 
     In the above configuration, the plate-shaped member may face a part of the coil end and may be fixed to the back surface at both end portions in a direction in which the plate-shaped member extends. 
     In the above configuration, the plate-shaped member may be provided with a second rib along a direction in which the plate-shaped member extends. 
     In the above configuration, the plate-shaped member may be provided with an overhanging portion that overhangs to an outer side of the coil end. 
     According to the present disclosure, the NV performance and safety of the vehicle can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG.  1    is a top view showing an example of a configuration of a vehicle drive system; 
         FIG.  2    is a left side view showing an example of the configuration of a vehicle drive system; 
         FIG.  3    is a front view showing an example of an internal configuration of a drive device when a cover is removed; 
         FIG.  4    is a plan view showing an example of a protective plate; 
         FIG.  5    is a rear view showing an example of a cover when the protective plate is removed; 
         FIG.  6    is a rear view showing an example of the cover when the protective plate is attached; 
         FIG.  7    is a front view showing an example of the cover; and 
         FIG.  8    is a partial cross-sectional view of the drive device along line A-A of  FIG.  7   . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Configuration of Vehicle Drive System 
       FIG.  1    is a top view showing an example of a configuration of a drive system of a vehicle  9 , and  FIG.  2    is a left side view showing an example of a configuration of the drive system of the vehicle  9 . In this example, a hybrid electric vehicle is mentioned as the vehicle  9  on which a drive device  1  is mounted. However, the present disclosure is not limited to this, and the vehicle  9  may be a battery electric vehicle. In addition, in  FIG.  1    and  FIG.  2   , arrows indicating a front-rear direction, a left-right direction, and an up-down direction with respect to a traveling direction of the vehicle  9  are shown. This direction is the same in  FIGS.  3 ,  5 ,  6 , and  7   .  FIG.  1    schematically shows an internal configuration when a vehicle body  90  is viewed from above, and  FIG.  2    schematically shows an internal configuration when the vehicle body  90  is viewed from a left side surface. 
     The vehicle  9  includes the drive device  1 , a pair of front wheels  91   f , a pair of rear wheels  91   r , a front drive shaft  95   f , a rear drive shaft  95   r , a pair of front side members  92 , an engine  93 , and a transaxle  94 . The pair of front wheels  91   f  is connected to each other via the front drive shaft  95   f , and the pair of rear wheels  91   r  are connected to each other via the rear drive shaft  95   r.    
     The engine  93  and the transaxle  94  are installed in a front compartment of the vehicle  9  and are connected to the front drive shaft  95   f . The front side members  92  are provided on the left and right sides of both the engine  93  and the transaxle  94 . The transaxle  94  is connected to the engine  93  so that the power of the engine  93  can be transmitted to the front drive shaft  95   f  via a transmission mechanism. 
     The transaxle  94  is provided with the drive device  1  including a rotary electric machine in addition to a power transmission mechanism such as a transmission. The drive device  1  has a case  10  for accommodating the rotary electric machine and a cover  11  for covering an end face of the rotary electric machine. The cover  11  is formed to be thin in order to make it easy to mount the drive device  1  on the vehicle  9  and to reduce the weight of the vehicle  9 . 
     The drive device  1  is arranged near, for example, the front side member  92  on the left side. Thus, when the vehicle  9  collides, the front side member may be damaged and come into contact with the cover  11 . In this case, there is possibility that a fragile portion of the cover  11  is damaged and that not only the fragments come into contact with the coil of the rotary electric machine during energization, but also the coil are exposed to the outside from the damaged portion. 
     Thus, the drive device  1  has a protective plate  12  that covers at least a part of the coil so that the cover  11  is not damaged and the coil is not exposed. The details of the configuration of the drive device  1  will be described below. 
     Configuration of Drive Device 
       FIG.  3    is a front view showing an example of the internal configuration of the drive device  1  when the cover  11  is removed. The drive device  1  is an example of a vehicle drive device, and drives the vehicle  9 . In  FIG.  2   , arrows indicating the front-rear direction and the up-down direction with respect to the traveling direction of the vehicle  9  are shown. 
     The drive device  1  includes rotary electric machines  2  and  3 , the case  10 , the cover  11 , and the protective plate  12 . The case  10  has an opening surface  100  that opens to the left direction with respect to the traveling direction of the vehicle  9 , and accommodates the rotary electric machines  2  and  3 . The case  10  has an outer edge portion  101  that defines the opening surface  100 . The outer edge portion  101  is provided with a screw hole  101   a  for assembling the cover  11  to the case  10 . The case  10  is made of aluminum as an example. 
     The rotary electric machine  2  is a motor that drives the front drive shaft  95   f , and the rotary electric machine  3  is a generator that generates electricity by the driving force of the engine  93 . The rotary electric machine  2  is located rearward with respect to the traveling direction of the vehicle  9 , and the rotary electric machine  3  is located forward with respect to the traveling direction. 
     The rotary electric machine  2  has a rotor  20  and a coil  21 . The rotor  20  has a rotation shaft  200  and a rotor core  201 . The rotary electric machine  2  is arranged so that the rotation shaft  200  is aligned in the left-right direction with respect to the traveling direction. 
     Further, the coil  21  is wound around teeth of a stator core (not shown) extending in the left-right direction with respect to the traveling direction. A coil end  210  is provided around the rotation shaft  200  and the rotor core  201  on an end face Sa of the rotor  20  in the direction of the rotation shaft  200 . The coil end  210  is an end portion of the coil  21  that is exposed to the outside. 
     The coil  21  is provided with a terminal  22  to which power is supplied from a power unit (not shown). The coil  21  generates a rotating magnetic field by a three-phase alternating current input from the terminal  22 . The rotor  20  rotates according to a rotating magnetic field. 
     Further, the rotary electric machine  3  has a coil  31  wound around a stator core (not shown) and a rotor  30  inside the stator core, similar to the rotary electric machine  2  described above. The rotor  30  has a rotation shaft  300  and a rotor core  301 . The rotary electric machine  3  is arranged so that the rotation shaft  300  is aligned in the left-right direction with respect to the traveling direction. The coil  31  is provided with a terminal  32  for outputting the generated electric power. The terminal  32  is connected to, for example, a battery (not shown). 
     The protective plate  12  is fixed to the back surface of the cover  11  so as to face a part of the coil end  210 . The position where the protective plate  12  is fixed is determined according to, for example, a surface rigidity of the cover  11 . When the protective plate  12  is fragile, for example, when the surface rigidity of the rear portion of the cover  11  is lower than the other portions with respect to the traveling direction of the vehicle  9 , the protective plate  12  is fixed so as to face the portion on rear side of the coil end  210  covered by the fragile portion of the cover  11 . 
     Thus, even when the front side member  92  is damaged and comes into contact with the fragile portion of the cover  11  and the portion is damaged, since the area on the rear side of the coil end  210  is covered by the protective plate  12 , the area on the rear side of the coil end  210  is suppressed from being exposed to the outside of the cover  11  and safety is ensured. 
       FIG.  4    is a plan view showing an example of the protective plate  12 . This will be described below with reference to  FIG.  4    together with  FIG.  3   . 
     The protective plate  12  is an example of a plate-shaped member facing at least a part of the coil end  210 . A plate surface of the protective plate  12  is formed so as to draw an arc according to the shape of a part of the coil end  210  that the plate surface is covering. The protective plate  12  is made of, for example, iron, but is not limited to this. 
     The protective plate  12  includes fixing portions  12   a  to  12   c  provided with screw holes  120   a  to  120   c  respectively, connecting portions  12   d  and  12   e  connecting between the fixing portions  12   a  to  12   c , and an overhanging portion  122  protruding upward from the fixing portion  12   a . The fixing portion  12   a  is provided at an upper end portion  12   u  and the fixing portion  12   c  is provided at a lower end portion  12   r  with respect to the traveling direction of the vehicle  9 . The fixing portions  12   a  and  12   b  are connected by the connecting portion  12   d , and the fixing portions  12   b  and  12   c  are connected by the connecting portion  12   d.    
     A step is provided between the fixing portions  12   a  to  12   c  and the connecting portions  12   d  and  12   e . The plate surfaces of the fixing portions  12   a  to  12   c  and the plate surfaces of the connecting portions  12   d  and  12   e  spread out at different positions in the left-right direction. A length of the connecting portion  12   d  extending between the fixing portions  12   a  and  12   b  is longer than A length of the connecting portion  12   e  extending between the fixing portions  12   b  and  12   c.    
     The connecting portion  12   d  is provided with a rib  121  along the extending direction thereof. The rib  121  protrudes toward the cover  11  side, but conversely, the rib  121  may protrude toward the coil end  210  side. As described above, since the protective plate  12  is provided with the rib  121  along the direction in which the protective plate  12  extends, its surface rigidity is increased as compared with the case without the rib  121 . The rib  121  is an example of a second rib. 
     The overhanging portion  122  functions as a handle when an operator attaches or detaches the protective plate  12 . The plate surface of the overhanging portion  122  is inclined toward the case  10  with respect to the plate surface of the fixing portion  12   a . The overhanging portion  122  protrudes to the outside of the coil end  210  when viewed from the rotation shaft  200 . Thus, the operator can easily attach or remove the protective plate  12 . 
     Further, the screw holes  120   a  to  120   c  are provided at an end portion  12   i  of the fixing portions  12   a  to  12   c  on the rotation shaft  200  side. That is, the screw holes  120   a  to  120   c  are provided on the inner peripheral side of the fixing portions  12   a  to  12   c  when viewed from the rotation shaft  200 . 
       FIG.  5    is a rear view showing an example of the cover  11  when the protective plate  12  is removed. A back surface Sb of the cover  11  is provided with shaft holding portions  112 ,  113  and fastening holes  115   a  to  115   c . The outer edge portion  110  fixed to the outer edge portion  101  of the case  10  is provided around the back surface Sb. The back surface Sb is defined by the outer edge portion  110 . The outer edge portion  110  is provided with a screw hole  110   a  for assembling the cover  11  to the case  10 . The cover  11  is made of aluminum as an example. 
     The shaft holding portions  112  and  113  have, for example, a substantially cylindrical shape, and internally hold the end portions of the rotation shafts  200  and  300 , respectively. The shaft holding portions  112  and  113  are provided with, for example, bearings corresponding to the rotation shafts  200  and  300 . The shaft holding portion  112  is an example of a holding portion that holds one end of the rotation shaft  200 . 
     The fastening holes  115   a  to  115   c  are used for fixing the protective plate  12 . The fastening holes  115   a  to  115   c  correspond to the screw holes  120   a  to  120   c  of the protective plate  12 , respectively. 
       FIG.  6    is a rear view showing an example of the cover  11  when the protective plate  12  is attached. In  FIG.  6   , the same reference numerals are given to the configurations common to those in  FIG.  5   , and the description thereof will be omitted. The protective plate  12  is attached so as to be substantially parallel to, for example, an end face Sa of the rotary electric machine  2 . 
     The screw holes  120   a  to  120   c  of the protective plate  12  overlap with the fastening holes  115   a  to  115   c  of the cover  11 , respectively. The protective plate  12  is screwed to the back surface Sb by screwing a screw  116  through the screw holes  120   a  to  120   c  into the fastening holes  115   a  to  115   c , respectively. Thus, the protective plate  12  can increase the rigidity of the cover  11  as compared with the case where the protective plate  12  is fixed to the cover  11  by fitting, for example. 
     As described above, the screw holes  120   a  to  120   c  are provided at the end portion  12   i  of the fixing portions  12   a  to  12   c  on the rotation shaft  200  side, and thus are located on the shaft holding portion  112  side. In the cover  11 , since the shaft holding portion  112  has higher rigidity than the other portions, by having the protective plate  12  fixed at the end portion  12   i  on the shaft holding portion  112  side by the back surface Sb, the rigidity of the cover  11  can be increased compared to the case in which the protective plate  12  is fixed on the opposite side of the end portion  12   i.    
     Further, as described above, the screw holes  120   a  and  120   c  are provided at the end portions  12   u  and  12   r  in the vertical direction with respect to the traveling direction of the vehicle  9 . As a result, the protective plate  12  is fixed to the back surface Sb at both end portions  12   u  and  12   r  in the extending direction. Thus, the vibration of the protective plate  12  due to the rotation of the rotary electric machines  2  and  3  is suppressed as compared with the case where the protective plate  12  is fixed at the center in the extending direction. 
       FIG.  7    is a front view showing an example of the cover  11 . When the cover  11  is viewed from the front, the shaft holding portions  112  and  113  are provided at positions overlapping the rotation shafts  200  and  300 , respectively. The substantially circular bottoms of the shaft holding portions  112  and  113  protrude to the front side of the cover  11 . 
     The cover  11  has a plurality of ribs  111  extending radially from the shaft holding portion  112  toward the outer edge portion  110 . The direction in which the ribs  111  extend is the direction from the rotation shaft  200  to the outside when the end face Sa (see  FIG.  3   ) in the direction of the rotation shaft  200  is viewed from the front. The ribs  111  are raised so as to protrude to the left with respect to the traveling direction of the vehicle  9 . 
     Thus, even when the cover  11  is thin (for example, 4 (mm)), the rigidity of the cover  11  in the extending direction of the rib  111  is improved by the rib  111 . However, the rigidity of the cover  11  in the direction orthogonal to the rib  111  is not improved. 
     Thus, the protective plate  12  is fixed to the back surface of the cover  11  so as to extend along a direction E orthogonal to the extending direction of the rib  111 . Thus, the rigidity of the cover  11  is improved not only in the direction in which the rib  111  extends but also in the direction E orthogonal to the direction in which the rib  111  extends. Thus, the surface rigidity of the cover  11  is improved. 
     Thus, the vibration of the cover  11  due to the rotation of the rotation shaft  200  in the shaft holding portion  112  is suppressed, and an NV performance of the vehicle  9  is improved. The ribs  111  are an example of the first ribs, and the number of ribs  111  is not limited, and the required number of ribs  111  may be provided in the fragile portion of the cover  11 . 
     However, as in this example, when a plurality of the ribs  111  is provided on the front surface of the cover  11 , the rigidity of the cover  11  is improved as compared with the case where only a single rib  111  is provided. Further, since the protective plate  12  is provided so as to bridge over the ribs  111  in the front view of the cover  11 , it is possible to further improve the surface rigidity of the portion between the ribs  111 . 
     Further, the direction in which the protective plate  12  extends does not necessarily have to be 90 degrees with respect to the extending direction of each rib  111 , and may be, for example, 75 degrees to 105 degrees. That is, when the protective plate  12  is substantially orthogonal along the direction E orthogonal to the direction in which the rib  111  extends, the surface rigidity of the cover  11  can be improved. 
     Further, a plurality of ribs  114  is also provided in the direction from the shaft holding portion  113  toward the outer edge portion  110 . Thus, the rigidity of the cover  11  is improved in the direction in which the ribs  114  extend. 
       FIG.  8    is a partial cross-sectional view of the drive device  1  along the line A-A of  FIG.  7   . A reference numeral F in  FIG.  8    is shown by enlarging an area indicated by a dotted circle. 
     One end of the rotation shaft  200  is held by the shaft holding portion  112 . The rotation shaft  200  is press-fitted into a center hole  201   a  of the rotor core  201 . 
     A stator core  212  is provided on the outer peripheral side of the rotor core  201 . The coil  21  is wound around the stator core  212 . The coil end  210  is provided around the rotation shaft  200  and is exposed from the stator core  212 . The end face of the coil end  210  on the cover  11  side faces the protective plate  12 . Thus, even if the cover  11  is damaged and the protective plate  12  is exposed to the outside, the exposure of the coil end  210  during energization is suppressed. 
     Between the shaft holding portion  112  and the outer edge portion  110 , the cover  11  includes a bending portion  117  that bends toward the coil end  210  side. A gap SP between an outer peripheral end  12   s  of the protective plate  12  and the bending portion  117  is smaller than the size of a finger. Thus, when at least a part of the protective plate  12  is exposed to the outside from the damaged portion of the cover  11  due to the breakage of the cover  11 , a driver or the operator is suppressed from directly touching the coil end  210  with their finger from the gap SP between the outer peripheral end  12   s  of the protective plate  12  and the bending portion  117 . 
     For example, a shortest distance d between the outer peripheral end  12   s  of the protective plate  12  and the bending portion  117  is 12 (mm) or less. Here, 12 (mm) correspond to a diameter of a fingertip of a finger. As a result, it is possible to suppress a finger from being inserted from the damaged portion of the cover  11  and coming into contact with the coil end  210  on the back side of the protective plate  12 . 
     The embodiments described above are examples of preferred embodiments of the present disclosure. However, the present disclosure is not limited to this, and various modifications can be made without departing from the gist of the present disclosure.