Abstract:
An attachment structure of an electromotor, which is connected to rear wheels, of a vehicle, includes: a sub frame provided at a rear portion of the hybrid vehicle, and including at least two first members which extend in a first direction that is a longitudinal direction of the vehicle and at least two second members which extend in a second direction that is a width direction of the vehicle and which include a front member and a rear member, the sub frame having a substantially rectangular shape in a third direction perpendicular to the first direction and the second direction, the sub frame to which the electromotor is assembled, a receptacle being provided at a front side of the sub frame; a rear motor mount provided at a rear side of the rear member, a position of the rear motor mount being substantially the same as a position of the electromotor in the third direction, the electromotor being provided at an upper side of the rear member; and a connection member provided at a lower side of the front member, the connection member to which the electromotor is fixed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to an attachment structure of an electromotor connected to rear wheels of a hybrid vehicle. 
         [0002]    There is a hybrid vehicle based on an FF vehicle (Front Engine, Front Drive vehicle) in which an electromotor is connected to rear wheels thereof and driving is enabled by an engine and the electromotor. In the FF vehicle, there is a structure in which a fuel tank is disposed below a rear seat to secure a wide interior space or accommodating space. In the meantime, regarding an example in which the electromotor is connected to the rear wheels, there is a structure in which an electromotor is provided adjacent to rear wheels to simplify the structure and to improve transmission efficiency (for example, see JP-A-11-165516). 
         [0003]    Due to this, for a hybrid vehicle based on the FF vehicle in which the electromotor is connected to the rear wheels, a structure is considered in which a fuel tank is arranged just before the electromotor. 
         [0004]    However, according to the hybrid vehicle having the above structure, when the vehicle is collided from the rear (hereinafter, referred to as rear collision), the electromotor may be forward pushed by the rear collision, thereby damaging the fuel tank. 
       SUMMARY 
       [0005]    It is therefore an object of the invention to provide an attachment structure of an electromotor capable of preventing a fuel tank from being damaged even when the electromotor is pushed out at the time of rear collision in a vehicle having an electromotor arranged at a rear portion of the vehicle. 
         [0006]    In order to achieve the object, according to the invention, there is provided an attachment structure of an electromotor of a vehicle, the electromotor which is connected to rear wheels, the attachment structure comprising: a sub frame provided at a rear portion of the hybrid vehicle, and including at least two first members which extend in a first direction that is a longitudinal direction of the vehicle and at least two second members which extend in a second direction that is a width direction of the vehicle and which include a front member and a rear member, the sub frame having a substantially rectangular shape in a third direction perpendicular to the first direction and the second direction, the sub frame to which the electromotor is assembled, a receptacle being provided at a front side of the sub frame; a rear motor mount provided at a rear side of the rear member, a position of the rear motor mount being substantially the same as a position of the electromotor in the third direction, the electromotor being provided at an upper side of the rear member; and a connection member provided at a lower side of the front member, the connection member to which the electromotor is fixed. 
         [0007]    The vehicle may include an internal combustion engine, and the receptacle may be a fuel tank that stores liquid fuel of the internal combustion engine. 
         [0008]    The connection member may include a mount part and an attachment part that is connected to the mount part, the front member may include a bracket at a lower side thereof, the mount part may be attached to the bracket, and the attachment part may be attached to the electromotor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view showing an assembly structure of an electromotor according to an illustrative embodiment of the invention. 
           [0010]      FIG. 2  is a perspective view showing an illustrative embodiment of a sub frame. 
           [0011]      FIG. 3  is a perspective view showing an illustrative embodiment of a front motor mount. 
           [0012]      FIG. 4  is a side view showing the assembly structure of the electromotor according to an illustrative embodiment shown in  FIG. 1 . 
           [0013]      FIG. 5  is a structural view showing an illustrative embodiment of a vehicle having assembled a rear-wheel electromotor thereto. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0014]    An illustrative embodiment of an attachment structure of an electromotor in a hybrid vehicle of the invention will be described. 
         [0015]      FIG. 5  shows a vehicle  10  that is an example of the hybrid vehicle. The vehicle  10  includes an engine  12  at the front portion, and a rear-wheel electromotor  14  for driving and a fuel tank  22  at the rear portion. Hereinafter, a driving direction of the vehicle  10  is referred to as the front and the opposite direction to the driving direction is referred to as the rear. Based on this, the right and the left are determined. In addition, the gravity direction is referred to as the lower and the opposite direction to the gravity direction is referred to as the upper. 
         [0016]    The vehicle  10  includes front wheels  16  at right and left sides of the front portion, and rear wheels  18  at right and left sides of the rear portion. The engine  12  is an internal combustion engine that uses gasoline as fuel and is mounted between the front wheels  16 . The engine  12  includes a transmission, a differential device and the like assembled thereto, which are not shown, and a rotational output of the engine  12  is transmitted to the front wheels  16  through the transmission, the differential device and the like. 
         [0017]    The vehicle  10  includes an ECU (Electronic Control Unit, which is not shown. The ECU obtains a variety of information such as operating states of accelerator and brake pedals, which are not shown, vehicle speed and a charged state of a battery  30 , which will be described later, and arbitrarily controls the engine  12 , the transmission and the like based on the information. In the meantime, it should be noted that the engine  12  is not limited to the gasoline engine. 
         [0018]    A generator  20  is provided at a side of the engine  12 . The generator  20  generates power by rotational forces input from the engine  12  or front wheels  16 . The battery  30  is provided at a central part in the underfloor space. The battery  30  is a battery that drives the vehicle  10  and has a relatively high capacity. The power generated in the generator  20  is stored in the battery  30 . In the meantime, it may be possible that the generator  20  is driven by power from the battery  30  to rotate the front wheels  16  or to start the engine  12 . The vehicle  10  includes at the rear portion a sub frame  50  including the rear-wheel electromotor  14  assembled thereto. 
         [0019]    Next, the sub frame  50  will be described. 
         [0020]      FIG. 2  shows the sub frame  50 . As shown in  FIG. 2 , the sub frame  50  has a substantially rectangular shape and includes tubular members  52  and  54 , which are main pipes provided at both sides of the vehicle  10 , a front cross member  56  provided at the front portions of the tubular members  52  and  54 , and a rear cross member  58  (a rear left-right extending member) provided at the rear portions of the tubular members  52  and  54 . 
         [0021]    The front cross member  56  is a member having a rectangular section and is provided in a width direction (right-left direction) of the vehicle  10 . End portions of the tubular members  52  and  54  are fixed to the front cross member  56  at an interval. In addition, the front cross member  56  is formed with fixing parts  60  at the both end portions thereof. The fixing parts  60  are fixed to a chassis frame  35 , which is shown in FIG.  5 , of the vehicle  10 . 
         [0022]    Further, the front cross member  56  is provided with a front motor mount bracket  62  at the approximate center thereof. The front motor mount bracket  62  has a substantially U shape and extends toward the lower side of the front cross member  56 . A front motor mount  64  is attached to the inner portion of the front motor mount bracket  62 . 
         [0023]      FIG. 3  shows the front motor mount  64 . As shown in  FIG. 3 , the front motor mount  64  includes a base  66  and an attachment piece  68  that is provided on the base  66 . The base  66  is formed with amount part  70  that is attached to the front motor mount bracket  62 . The attachment piece  68  is a plate member having a substantially triangular shape and has attachment holes  71  formed at three corner portions thereof. 
         [0024]    The tubular members  52  and  54  each of which has a tubular shape are respectively formed into a substantially symmetrical shape with respect to a longitudinal direction (front-rear direction) of the vehicle  10 . The tubular members  52  and  54  extend rearward from the front cross member  56  with being substantially flush with the front cross member  56  and are bent at the vicinities of the centers thereof so that the tubular members  52  and  54  are opened outwardly. Rear end portions of the tubular members  52  and  54  are respectively connected to the right and left end portions of the rear cross member  58 . 
         [0025]    Fixing parts  72  are provided at connection portions between the tubular members  52  and  54  and the rear cross member  58 . The fixing parts  72  are fixed to the chassis frame  35 , which is shown in  FIG. 5 , of the vehicle  10 . 
         [0026]    The rear cross member  58  is a member having a rectangular section, and has both end portions that are bent upwardly. The both end portions of the rear cross member  58  are connected to the tubular members  52  and  54 . A central part of the rear cross member  58  is slightly protruded forward. Attachment parts  74  are provided on rear faces of the both end portions of the rear cross member  58 . As shown in  FIG. 1 , a rear motor mount  76  that is a structure member is fixed to the attachment parts  74  with screws. 
         [0027]      FIG. 1  shows a state in which the rear-wheel electromotor  14  is assembled inside the sub frame  50 . The rear-wheel electromotor  14  has a cylindrical shape and is assembled with a direction of an output shaft, which is not shown, thereof being parallel with the width direction of the vehicle  10 . 
         [0028]    The rear-wheel electromotor  14  includes a terminal connection part  24  at the upper portion thereof. The terminal connection part  24  is a connection port including a predetermined number of connection terminals, which are not shown, and is disposed at the front side of a rear wall of the rear motor mount  76 . The terminal connection part  24  is connected with one end of a power line  34 . The power line  34  has a diameter of about 1 cm and is thick enough to enable predetermined current to flow therein. The other end of the power line  34  is connected to a power control unit  32  that will be described below. The power line  34  connected to the terminal connection part  24  is upwardly bent from the terminal connection part  24  and is connected to a connection port  36  of the power control unit  32 . The connection port  36  is disposed at the front side of the rear wall of the rear motor mount  76 , in the same manner as the terminal connection part  24  of the rear-wheel electromotor  14 . 
         [0029]    A decelerating differential device  38  is provided at an output shaft section of the rear-wheel electromotor  14 . The decelerating differential device  38  includes a decelerating gear and a differential gear therein, and right and left rear wheel driving shafts, which are not shown, are connected to an output end portion of the differential gear. The rear wheel driving shafts are respectively connected to the rear wheels  18  and transmit rotational output of the rear-wheel electromotor  14  to the right and left rear wheels  18  while performing the differential motion. In the meantime, the decelerating differential device  38  may have an accelerating gear therein, rather than the decelerating gear. 
         [0030]    The decelerating differential device  38  includes an attachment hole, which is not shown, at a side face thereof, and the attachment piece  68  of the front motor mount  64  is fixed to the decelerating differential device  38  with a screw  73  through the attachment hole, as shown in  FIG. 4 . The rear-wheel electromotor  14  is thus attached to the front cross member  56 . 
         [0031]    The rear-wheel electromotor  14  is attached in such a way that a center of rotation of the rear-wheel electromotor  14  is substantially flush with the rear cross member  58 . Namely, height of the center of the rotation of the rear-wheel electromotor  14  is substantially the same as height of the rear cross member  58 . The fuel tank  22  is provided at the front side of the front cross member  56 . The fuel tank  22  is a tank that stores liquid fuel of the engine  12 . The fuel tank  22  is provided at a position that is below the floor face of the vehicle  10  and is substantially flush with the front cross member  56 . 
         [0032]    The rear cross member  58  extends at the lower side of the rear-wheel electromotor  14  at a slight interval with the rear-wheel electromotor  14 . In addition, the rear motor mount  76  extends at the rear side of the rear-wheel electromotor  14  at a slight interval with the rear-wheel electromotor  14 . 
         [0033]    The power control unit  32  is provided above the rear-wheel electromotor  14 . The power control unit  32  is attached to the chassis frame  35  by a stay and the like and controls the charge and discharge of the battery  30  and an operation of the rear-wheel electromotor  14  in response to instructions from the ECU. 
         [0034]    The power control unit  32  includes the connection port  36  and is connected with the power line  34 . The power control unit  32  is connected to the rear-wheel electromotor  14  through the power line  34 . The power control unit  32  is also connected to the battery  30  through the power line  34 . 
         [0035]    An external power supply connection port  33  is provided at, for example, a rear side face of the vehicle  10 . The external power supply connection port  33  is a connection port to which an external power supply is connected. The battery  30  is charged using the external power supply that is connected to the external power supply connection port  33 . 
         [0036]    Next, operational effects of the attachment structure of the electromotor of the hybrid vehicle will be described. 
         [0037]    When the engine  12  is operated and power is thus transmitted to the front wheels  16 , the vehicle  10  drives in a front-wheel driving manner. In addition, when the power is supplied to the rear-wheel electromotor  14  from the power control unit  32 , the driving force of the rear-wheel electromotor  14  is transmitted to the rear wheels  18  through the decelerating differential device  38 , and the vehicle  10  drives in a rear-wheel driving manner. The driving of the vehicle  10  may drive in the front-wheel driving manner, the rear-wheel driving manner, or an all-wheel driving manner in which all of the front and rear wheels drive at the same time. The rear wheels  18  are supported by the suspension provided at the sub frame  50  and arbitrarily operate in the upper and lower directions. 
         [0038]    When the vehicle  10  is collided from the rear side, the impact force due to the rear collision is absorbed while breaking a crushable zone a, which is shown in  FIG. 5 , of the rear portion of the vehicle  10 . when the impact force is within a predetermined range, the vehicle is broken only within the crushable zone a, and the portion of the vehicle which is arranged at the front side of the rear motor mount  76  is little damaged. 
         [0039]    However, when the impact force is high and is thus applied to the rear motor mount  76 , the rear motor mount  76  is forward deformed. When the impact is absorbed as the rear motor mount  76  is deformed, the rear-wheel electromotor  14  is not damaged. 
         [0040]    When the impact is higher and thus the rear motor mount  76  is highly displaced forward while deforming the sub frame  50 , the rear motor mount  76  pushes the rear-wheel electromotor  14 . Hence, the front motor mount bracket  62  is damaged and the rear-wheel electromotor  14  is forward moved. However, the rear-wheel electromotor  14  is hindered from moving forward while contacting the front cross member  56  and is moved obliquely downward so that the rear-wheel electromotor  14  moves below the front cross member  56 . 
         [0041]    Thereby, even when the high impact is applied, the rear-wheel electromotor  14  is moved obliquely downward. Thus, the damage of the fuel tank  22  due to the contact of the rear-wheel electromotor  14  is not caused. 
         [0042]    In addition, the rear cross member  58  is provided below the rear-wheel electromotor  14 . Accordingly, even when the front motor mount bracket  62  is broken, the rear-wheel electromotor  14  is put on the rear cross member  58  and is not dropped on the road from the vehicle  10 . 
         [0043]    In the above exemplary embodiment, the fuel tank  22  is arranged at the front side of the rear-wheel electromotor  14 . However, the invention is not limited to the fuel tank  22  and the other member may be also possible. For example, expensive and important parts such as battery, fuel cell and inverter may be arranged at the front side of the rear-wheel electromotor  14 . 
         [0044]    According to an aspect of the invention, the attachment structure of the electromotor of the hybrid vehicle is configured as follows. 
         [0045]    The hybrid vehicle has such a structure that an electromotor is connected to rear wheels of an FF vehicle (Front Engine, Front Drive vehicle). The vehicle has a sub frame having a substantially rectangular shape at the rear portion thereof. For example, the sub frame is formed into the rectangular shape by arranging members, which extend in a longitudinal direction (front-rear direction), at right and left sides and attaching a front cross member and a rear cross member at front and rear parts of the members, respectively. The sub frame may have a suspension assembled at the rear portion of the vehicle and may hold the rear wheels through the suspension so that the rear wheels can move vertically. In addition, a rear motor mount, which is a structure member, is attached to the rear side of the sub frame. 
         [0046]    The electromotor is attached at an inside of the sub frame, i.e., a space surrounded by the above described members which arranged at the right and left sides and which extend in the front-rear direction, the front cross member, the rear cross member and the rear motor mount. 
         [0047]    To be more specific, the electromotor is attached as follows. A bracket, which is a front motor mount bracket, to which a connection member, which is a front motor mount, is attached, is provided at the front cross member. The front motor mount includes amount part at the front portion thereof and an attachment part at the rear portion thereof which is integrally formed with the mount part. The mount part of the front motor mount is attached to the bracket, and the attachment part is attached to the electromotor. Thereby, the electromotor is fixed to the sub frame. 
         [0048]    In addition, the rear cross member is disposed below the electromotor at a slight interval with the electromotor. The rear motor mount is provided at the rear side of the electromotor at a slight interval with the electromotor. Both end portions of the rear motor mount are attached to right and left end portions of the rear cross member. Furthermore, the electromotor is attached to the sub frame at a position that is slightly higher than a center of the mount part of the front motor mount. A fuel tank is disposed at the front side of the front cross member at a position that is substantially the same in height as a position of the front cross member, at a slight interval with the front cross member. 
         [0049]    The attachment structure of the electromotor of the invention has following effects. Since the electromotor is provided adjacent to the rear wheels, it is possible to drive the vehicle while effectively driving the rear wheels. When the vehicle is collided from the rear side, the rear motor mount receives the impact by the rear collision. Since there is a gap between the rear motor mount and the electromotor, the electromotor is not damaged. 
         [0050]    When the energy of the rear collision is high and thus the rear motor mount or rear cross member is deformed, the electromotor is pushed forward and the front cross mount is thus damaged. However, the electromotor is hindered from moving by the front cross member provided at the front side of the electromotor, so that the electromotor is pushed out obliquely downward. 
         [0051]    Thereby, even when the electromotor is pushed from the rear side, the electromotor moves without contacting the fuel tank. Accordingly, it is possible to prevent the fuel tank from being damaged due to the electromotor. In addition, even when the front motor mount is damaged, the electromotor is put on the rear cross member and is prevented from being completely detached from the vehicle. 
         [0052]    The present invention can be applied to an electric vehicle or hybrid vehicle having an electromotor connected to rear wheels.