Patent Publication Number: US-2011068622-A1

Title: Vehicle high voltage cable layout structure

Description:
FIELD OF THE INVENTION 
     The invention relates to a layout structure for a high voltage cable of a vehicle. More particularly, in a high voltage energy system which is installed in an electric vehicle (EV) in a broad sense including a hybrid electric vehicle (HEV), a fuel-cell electric vehicle (FCHEV), and the like, the invention relates to a layout structure for a high voltage cable of a vehicle, which is used for coupling a battery and a generator/drive motor or an inverter. 
     BACKGROUND OF THE INVENTION 
     In an electric vehicle (EV) (hereinbelow, referred to by the term “vehicle”) in a broad sense including a hybrid electric vehicle (HEV), a fuel-cell electric vehicle (FCHEV), and the like, as illustrated in  FIG. 6 , both of a battery (cell)  125  and a fuel tank  126  are attached in a rear portion of a vehicle  101 . The battery  125  is arranged at the vehicle rear side of the fuel tank  126  and over a rear floor panel of a luggage compartment  105 . A high voltage cable  132  is arranged so as to be connected to the battery  125  and to be extended toward a vehicle front portion. 
     In this case, in a layout of the high voltage cable  132  for coupling an inverter  131  arranged in an engine compartment  103  with the battery  125  behind a rear seat  127 , since the fuel tank  126  is present, the cable  132  is arranged in such a manner that at a position near a front portion of the fuel tank  126 , the cable is temporarily led towards the outside of the vehicle (outside-car route: R 2 ) and, thereafter, penetrates a grommet  137 , and is arranged in an area corresponding to the passenger compartment  104  (inside-car route: R 1 ). 
     In a piping structure for a battery for a vehicle according to assignee&#39;s Japanese published patent application No. 2004-148850, an exhaust hose is held by holding means along a power line and the exhaust hose and the power line are integrated and extended from a through-hole to the outside of the passenger compartment. 
     Examined Japanese patent application No. 3838505 discloses an arranging structure of a power line of a vehicle in which the power line for communicating a motor for running and a battery is arranged along a side member without being curved with a small curvature. 
     PROBLEM TO BE SOLVED BY THE INVENTION 
     In the layout structure of the high voltage cable of a vehicle according to  FIG. 6 , hitherto, since the high voltage cable  132  passes through the outside of the vehicle as illustrated in  FIG. 7 , in the presence of an external lateral force, there is a danger of the high voltage cable  132  being damaged by vehicle body deformation P. 
     Since the high voltage cable  132  passes through a region near the fuel tank  126 , there is a danger of the high voltage cable  132  coming into contact with the fuel tank  126  due to the vehicle body deformation P when the external force acts and the high voltage cable  132  becoming damaged, and there is a need to improve this arrangement. 
     In the related art, performance of the electric vehicle depends largely on advancement in battery development. It is necessary for a battery (pack) of high electric capacity and large volume and weight to be mounted in many electric vehicles (EV) in order to guarantee a long cruising distance. 
     There is a tendency for the battery assembly to grow in size irrespective of size of vehicle in order to achieve vehicle performance (for example, cruising distance over which the vehicle can run continuously per battery charge) comparable to that of gasoline and diesel engine powered vehicles. 
     In the electric vehicle (EV), in order to mount such a large battery, initially, a vehicle in which a space between the ground and the floor panel of the vehicle body is large is taken as a basis. In the case where the fuel tank is attached under a rear portion of the vehicle, the battery is mounted under the floor panel in front of the fuel tank, or over the floor panel over the fuel tank. By mounting the battery at such a position, in the case of a large vehicle, the battery, constituting a heavy object, can be attached near the center of the vehicle. Thus, the benefits of not only high running stability and excellent ride comfort for the vehicle can be secured but also product performance of the vehicle can be assured in terms of usability without reducing space for the luggage compartment at the rear of the vehicle. 
     The high voltage energy system can be concentrated on the region under the floor panel near the vehicle center to a certain extent and, since an area where the high voltage cable is arranged is also narrow, the high voltage energy system can be easily protected against external forces from the front, rear, right, and left of the vehicle. There is consequently an advantage in that the number of limitations which should be taken into consideration can be reduced. 
     However, either a choice has to be made between adopting a basic vehicle which is limited to a relatively large vehicle, or being obliged to provide a vehicle having a dedicated body design. In both cases, a disadvantage is encountered in that it is difficult to provide a vehicle at a low price as a small compact vehicle. 
     In use in an urban area involving a large number of starting/stopping operations of the vehicle due to traffic jams or the like, the number of passengers is small, and trip distance per run is short, this contradictory situation leads it to be considered that, from a viewpoint of fuel economy, the compact small vehicle is the better vehicle. 
     As an example where such a system is installed in a compact small vehicle, we have for instance, assignee&#39;s Japanese published patent application No. 2004-148850 mentioned above, or similar cases. This fundamentally relates to a hybrid vehicle converted in such a manner that an electric generator, a battery, and the like are added to a gasoline-powered vehicle in which an engine is used as a power unit, thereby enabling drive assistance and regenerative power generation to be performed. 
     Although the vehicle according to assignee&#39;s Japanese published patent application No. 2004-148850 cannot be regarded as an electric vehicle because it cannot run only using the motor, it is a hybrid vehicle. The high voltage energy system including the battery, generator/drive motor, inverter, and high voltage cable, the engine, and the fuel tank are mounted in such a vehicle. 
     Although there is very little change to the vehicle body by way of a converted car, when we look at the high voltage cable, in the area between the battery and inverter mounted in the rear portion of the vehicle and the engine in the vehicle front portion, the cable is arranged so as to be exposed to the outside in the regions under the fuel tank and under the floor panel. 
     Particularly, regarding the layout of the high voltage cable which passes through the area where the fuel tank is attached, although it is located at the center in the vehicle width direction, the cable is arranged so as to pass through the region under the fuel tank. But in view of the small size of the vehicle corresponding to a commuter car with extremely short front to back dimensions, although such a layout is a rectilinear simple arrangement, performance is commensurate with safety. 
     When constructing an electric vehicle (EV) taking a compact small vehicle as a basis, in a region near the vehicle center, there is an emphasis on providing the space required to ensure adequate passenger space and ensuring comfort. Therefore, in order to mount the large battery, additional factors such as carrying capacity and convenience of the luggage compartment or the like are sacrificed and the battery of which both electrical storage capacity and volume/weight are high is mounted at the rear portion of the vehicle. 
     In the case where the electric vehicle (EV) is a hybrid vehicle in which a fuel tank for a fuel having high volatility (particularly, liquid fuel such as gasoline, diesel fuel, alcohol-blended fuel, or the like), a system for supplying its power unit and the like have been mounted, it is essential to pay sufficient attention to the relation between these fuels and electricity. Particularly, it is necessary to make an effort to assure safety under ordinary conditions of use so as not to encourage mutual influence between them and provoke severe combustion. 
     In the case where both the battery having high electrical storage capacity and volume/weight as well as the fuel tank are mounted towards the rear of the vehicle, even in a case where the vehicle is damaged by an external force, it is necessary to avoid mutual influence between the fuel and the electricity. That is to say the electricity should be isolated from the fuel and the possibility of short-circuiting be reduced as much as possible. 
     In assignee&#39;s foregoing Japanese published patent application No. 2004-148850 or similar cases, since the inverter is also enclosed in the luggage compartment, even if current flow is considered, it is desirable that the cable does not pass through the inside of the area corresponding to the passenger compartment, and it can be considered that even with a layout in which the cable passes out of the vehicle, then, by providing a protective member, necessary performance can be assured to prevent damage to the cable. Nevertheless, it is desirable to make use of a structure adapted to further improve protective performance. 
     Moreover, if the battery has been equipped with a charger for charging it, since a considerable amount of heat is generated during charging using the charger, a device for cooling is necessary. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide a layout structure for a high voltage cable of a vehicle, in which even in the case where the vehicle is damaged to an extent where it suffers considerable deformation as a result of an external force, a resulting influence on the high voltage cable is avoided as much as possible, mutual influence between fuel and electricity is avoided, the number of installation parts for protecting the high voltage cable and the like is kept to a minimum, and a charger to charge the battery is provided with a structure for controlling its temperature, by the use of an appropriate layout structure for the high voltage cable connected to the battery. 
     According to the invention, there is provided a layout structure for a high voltage cable of a vehicle in which a battery and a fuel tank are mounted in a vehicle rear portion, the battery is arranged at a vehicle rear side of the fuel tank and over a rear floor panel, and the high voltage cable is arranged so as to be connected to the battery and to be extended toward a vehicle front portion, 
     wherein the high voltage cable is arranged at a position over the rear floor panel where it vertically overlaps with the fuel tank at a central portion thereof in a vehicle width direction so as to lie substantially along a front/rear center axis of the vehicle and is arranged in such a manner that ahead of the position where the cable overlaps the fuel tank, the cable enters an area corresponding to a passenger compartment leaving a standard surface of the rear floor panel, and in front thereof, the cable passes through a region below a standard surface of a front floor panel. 
     According to this layout structure for the high voltage cable of the vehicle of the invention, the high voltage cable is arranged substantially at the vehicle center and damage to the high voltage cable can be avoided even if the vehicle body is subject to deformation under the action of an external force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic constructional diagram of a vehicle in which a high voltage cable is arranged. 
         FIG. 2  is a plan view of the vehicle. 
         FIG. 3  is a perspective view looking into an area corresponding to the passenger compartment of the vehicle when seen from above. 
         FIG. 4  is a bottom view of a front floor panel of the vehicle seen from below. 
         FIG. 5  is a perspective view of a rear portion of the vehicle seen from above. 
         FIG. 6  is a schematic constructional diagram of a vehicle in which a high voltage cable is arranged according to the prior art. 
         FIG. 7  is an explanatory diagram illustrating a state where an external force has acted from the side and the vehicle body has undergone deformation with the prior art high voltage cable arrangement in a vehicle. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     According to the invention, the aim of avoiding damaging a high voltage cable even when vehicle body deformation has occurred under the effect of an external force is accomplished by arranging the high voltage cable to run substantially at the center of the vehicle. 
     An embodiment of the invention will be specifically described in detail hereinbelow with reference to the drawings. 
       FIGS. 1 to 5  illustrate an embodiment of the invention. 
     In  FIGS. 1 and 2 , reference numeral  1  denotes an electric vehicle (EV) (hereinbelow, referred to as the “vehicle”) in a broad sense covering a hybrid electric vehicle (HEV), a fuel-cell electric vehicle (FCHEV), and the like;  2  a vehicle body;  3  an engine compartment of a vehicle front portion;  4  an area corresponding to the passenger compartment in the central portion of the vehicle;  5  a luggage compartment at a vehicle rear portion;  6  front wheels;  7  rear wheels;  8  headlights;  9  side frames;  10  a floor panel of the vehicle  2 ; and  11  a dash panel. 
     An engine generator unit  13  and a drive motor gear casing unit  14  making up an on-vehicle unit (engine ASSY)  12  are arranged in the engine compartment  3 . 
     Apparatuses such as a radiator of a cooling system for the internal combustion engine, a radiator of a cooling system for the generator/drive motor, capacity for an air conditioning system, and the like are arranged in a front portion of the engine compartment  3 . Apparatus such as an electric compressor for the air conditioning system, a water pump of the cooling system for the generator/drive motor, and the like are arranged in a lower portion of the engine compartment  3 . In the foregoing cooling system for the generator/drive motor, a generator  16 , a drive motor  17 , and an inverter  31 , which will be described hereinafter, are respectively cooled. 
     The engine generator unit  13  is made up by integrating: an engine  15  starting and stopping of which can be switched at any time while the vehicle  1  is running and a generator  16  mechanically coupled with the engine  15 . The engine generator unit  13  does not generate direct vehicle propulsion but generates electrical power for powering the drive motor gear casing unit  14 . That is, the vehicle  1  is based on a series type hybrid driving system. If the engine generator unit  13  is omitted, the vehicle  1  is an electric vehicle in a narrow sense. 
     When a specific condition in which the amount of charge in the battery  25 , which will be described hereinafter, has decreased or similar situation is satisfied, the engine generator unit  13  starts up and drives the engine  15  and rotates the generator  16  so as to perform power generation. A longitudinal direction of the unit  13  is oriented in the vehicle width direction and in both of the right and left edge portions, the unit  13  is fixed to the side frames  9  of the vehicle  2  through mounts. The crankshaft height of the engine  15  and the height of the rotational axis of the generator  16  are lower than the height of the rotational axis of the drive motor  17 , which will be described hereinafter, thereby contributing to keeping center of gravity low. 
     The drive motor gear casing unit  14  is a true unit for propelling the vehicle  1 . In order to generate vehicle propulsion and propagate driving power, the unit  14  is made up by integrating: the drive motor  17  for generating the vehicle propulsion; and a gear casing  18  for propagating motive power in association with the drive motor  17 . 
     The drive motor gear casing unit  14  is fixed to an upper surface side of a subframe (suspension frame)  19  of the vehicle body  2  through a rear mount adapted to isolate vibration by an elastic member. The unit  14  propagates the driving power from the gear casing  18  to driveshaft means. Alternatively, the unit  14  can propagate the driving power through an intermediate axle if necessary with regard to balance, vibration, and the like to right and left driving wheels. 
     The gear casing  18  has, in its upper portion, an input shaft which is coaxial with the rotational axis of the drive motor  17  and has, in its lower portion, an output shaft coupled to driveshaft means. A reduction gear and a differential gear are enclosed in the gear casing  18 . The external shape of the gear casing  18  can be formed in such a manner that it is relatively long in a vertical direction and is short in a vehicle front/rear direction. The intermediate shaft is arranged under the drive motor  17 . 
     The engine generator unit  13  and the drive motor gear casing unit  14  are coupled so as to be mechanically integrated at the parts thereof which are closest together and, thereafter, mounted onto the vehicle body  2  through three mounts (right and left mounts and a rear mount). Ordinarily, they are stably supported by the three mounts and, in the presence of a load resulting from an external force from the front, the on-vehicle unit  12  in which the engine generator unit  13  and the drive motor gear casing unit  14  have been integrated can shift almost horizontally toward the rear of the vehicle. 
     The rotational axis of the drive motor  17  is arranged at a position higher than the crankshaft of the engine  15  and the rotational axis of the generator  16 . Thus, the casing of generator  16  and the casing of drive motor  17  are arranged so that a part of them overlaps in the vertical direction when seen in plan view (or when seen from the lower surface), thereby reducing the length of on-vehicle unit  12  in a vehicle front/rear direction X. At the same time, large dimensions for movement can be assured for the mounting space in vehicle body  2 . Particularly, dimensions between the dash panel  11  and the casing of the drive motor  17  are assured. 
     The floor panel  10  of the vehicle body  2  is made up by a front floor panel  20  at the vehicle front portion and a rear floor panel  21  at the vehicle rear portion. A standard surface of the rear floor panel  21  is set so as to be higher than a standard surface of the front floor panel  20 . A central tunnel  22  is formed in the front floor panel  20  in a central portion in the vehicle width direction Y so as to be oriented in the vehicle front/rear direction, and a steering wheel attaching portion  23  is formed in the front portion. 
     An exhaust pipe  24  making up an exhaust system of the engine  15  passes through a region under the engine  15 , forms a two-stage crank-shaped bent portion, passes through an internal space of the central tunnel  22  of front floor panel  20 , and is extended toward the vehicle rear portion. The two-stage crank-shaped bent portion of exhaust pipe  24  provides a surround shape in order to bypass the gear casing  18  thereby increasing the distance from the engine  15 , and reducing the influence of heat radiation. 
     In the vehicle rear portion, both the battery (pack)  25  and fuel tank  26  are mounted in the luggage compartment  5  located over the rear floor panel  21 . 
     As illustrated in  FIGS. 3 and 4 , a height difference H between a standard surface F 1  of the front floor panel  20  and a standard surface F 2  of the rear floor panel  21  is set to a value similar to the height of fuel tank  26 . The fuel tank  26  is supported and fixed to the rear floor panel  21  under the rear floor panel  21  and in front of a suspension system or axle shafts of the rear wheels. 
     The battery  25  is arranged on the vehicle rear side of the fuel tank  26  and over the rear floor panel  21 . 
     The external shape of the fuel tank  26  is flat in the vertical direction and in the vehicle front/rear direction X. The fuel tank  26  is mounted so that its longitudinal direction coincides with the vehicle width direction Y. A volatile fuel which is in a liquid state at an ordinary temperature is stored in the fuel tank  26 . 
     A seat  27  acting as a rear seat is attached across rear floor panel  21  over the fuel tank  26 . 
     In the rear floor panel  21  on the vehicle rear side of the fuel tank  26 , a housing  29  having an internal space  28  with a height similar to the height difference H between the standard surface F 1  of the front floor panel  20  and the standard surface F 2  of the rear floor panel  21  is formed at substantially the rear side of the axle shafts of the rear wheels. 
     A high voltage energy system  30  is mounted in the vehicle  1 . In the high voltage energy system  30 , the inverter  31  which is connected to the battery  25  and controls the drive motor  17  is arranged in an upper portion of the engine compartment  3 . The inverter  31  is arranged so as to cover regions over both the generator  16  at the front side and the drive motor  17  at the rear side. 
     Since auxiliary equipment of an intake system is arranged over the engine  15 , when mounting to the vehicle  1 , all units are assembled together with the inverter  31  and the on-vehicle unit  12 , and they are integratedly mounted to the vehicle  1 . 
     A high voltage cable  32  extending generally toward the vehicle front portion as a whole and connected to the inverter  31  is connected at an edge portion of the battery  25 . The high voltage energy system  30  includes the generator  16 , drive motor  17 , battery  25 , inverter  31 , and high voltage cable  32 . 
     The high voltage cable  32  is covered with a protective tube and is used to connect mainly the battery  25  and the inverter  31 . Therefore, an almost constant voltage DC current flows and electromagnetic influence is extremely small. 
     As illustrated in  FIGS. 1 and 2 , a part of the high voltage cable  32  is arranged in the area corresponding to the passenger compartment  4 . In a region over the rear floor panel  21 , after the cable  32  has extended from one end of the battery  25  to the front side, and is bent in the vehicle center direction along the circumference of the battery  25  and reaches a position near the center in the vehicle width direction Y, it is again extended toward the vehicle front side. 
     At a position near a region where the rear floor panel  21  stands up from the front floor panel  20 , the high voltage cable  32  penetrates the front floor panel  20  from an upper direction toward a lower direction of the rear floor panel  21  and, further, is extended along the lower surface of the front floor panel  20  toward the vehicle front portion in the vehicle front/rear direction X. 
     That is, as illustrated in  FIGS. 1 and 2 , the high voltage cable  32  is arranged at a position over the rear floor panel  21  which vertically overlaps with the fuel tank  26  at a central portion thereof in the vehicle width direction Y so as to lie substantially along a front/rear center axis  1 C of the vehicle  1 . The high voltage cable  32  is arranged in such a manner that ahead of the position where the cable overlaps the fuel tank  26 , the cable enters the area corresponding to the passenger compartment  4  from the standard surface F 2  of the rear floor panel  21  (we shall call this the inside-car route: R 1 ), and in front thereof, the cable passes through a region below the standard surface F 1  of the floor panel  20  on the right side in the vehicle width direction Y of the front/rear center axis  1 C of the vehicle  1 . 
     At a lower surface of the floor panel  20  (we shall call this the outside-car route: R 2 ), the high voltage cable  32  is extended at a position between each side frame  9  and the central tunnel  22  in the vehicle front/rear direction X so as to follow them. At a position where the floor panel  20  is coupled with the dash panel  11 , as illustrated in  FIGS. 3 and 4 , after the high voltage cable  32  has partially entered an edge portion space of the central tunnel  22 , it is extended along the surface of the dash panel  11  which faces a back surface of the gear casing  18 . The subframe  19  is provided at a lower position of dash panel  11 . This position also corresponds to a position where the rear mount of the engine generator unit  13  is arranged. 
     In an internal space of a front edge of the central tunnel  22  and in a space also including a space sandwiched by the subframe  19 , the high voltage cable  32  is arranged so as to avoid any interference with a steering rack. 
     Further, the high voltage cable  32  is arranged so as to be distanced from the exhaust pipe  24  to the opposite side in the vehicle width direction Y, thereby avoiding thermal influence and any interference in the narrow limited space. At the same time, since the high voltage cable  32  is extended from a high position serving as an upper portion of the internal space of the central tunnel  22  toward the front side of the front surface of the dash panel  11 , a length range sandwiched between the dash panel  11  and the on-vehicle unit  12  is reduced, thereby preventing the high voltage cable  32  from being sandwiched between both of the dash panel  11  and the on-vehicle unit  12  when the space between the dash panel  11  and the on-vehicle unit  12  is reduced as a result of deformation. 
     In the rear floor panel  21 , as illustrated in  FIG. 5 , a charger  33  associated with the battery  25  is enclosed in the internal space  28  of the housing  29 . An auxiliary frame including a cross member  34  is provided for the housing  29  and a structure creating an impedance to an external force from the rear or the side, thereby suppressing deformation is created. 
     When seen in plan view, after the high voltage cable  32  has extended from one end of the battery  25  to the front side, when it is bent in the vehicle center direction so as to lie along the circumference of the battery  25  and reaches a position near the center in the vehicle width direction Y, it is again extended toward the vehicle front side. The high voltage cable  32  in this portion enters the housing  29  having the internal space  28  in the vertical direction and is arranged so as to pass through the circumferential space of the charger  33 . 
     At a position adjoining the position where the rear floor panel  21  stands up from the front floor panel  20 , the high voltage cable on the rear side arranged over the rear floor panel  21  is arranged so as to become the high voltage cable  32  on the front side arranged under the front floor panel  20  and to enter the area corresponding to the passenger compartment  4 , leaving the standard surface F 2  of the rear floor panel  21 . At this position, as illustrated in  FIGS. 3 and 5 , a rising portion  35  of the rear floor panel  21  is sandwiched between the front surface of the fuel tank  26  and the front floor panel  20 . 
     A penetrating portion  36  where the high voltage cable  32  penetrates the front floor panel  20  is provided at a position where it avoids the central tunnel  22  of the front floor panel  20  and is slightly deviated in the vehicle width direction Y from the center line  1 C of the vehicle  1 . 
     As said, in a region over the rear floor panel  21 , that is, in a portion extending to the front of the vehicle in the central area of the vehicle width direction Y, the high voltage cable  32  overlaps with the fuel tank  26  in the vertical direction so as to transverse in the front/rear direction. 
     As illustrated in  FIG. 4 , a grommet  37  is provided in the portion where the high voltage cable  32  penetrates the front floor panel  20 . 
     The high voltage cable  32  of the inside-car route R 1  at the grommet  37  and compartment  4  side is covered with a first cover member (a cover made of sheet metal)  38 . The first cover member  38  covers: the area of penetration  36  for entry to the area corresponding to the passenger compartment  4  upon leaving the standard surface of the rear floor panel  21  on the layout path of high voltage cable  32 ; the rising portion  35  of the rear floor panel  21 ; and a floor portion  39  corresponding to the rear seat  27 . 
     As illustrated in  FIG. 5 , a ventilation duct  40  for cooling air flow is provided in parallel with the high voltage cable  32  for controlling the temperature of charger  33 . 
     The ventilation duct  40  is made of a resin. In a manner similar to the high voltage cable  32 , in a region over the rear floor panel  21 , that is, in a portion extending in the vehicle front side in the central area in the vehicle width direction Y, the ventilation duct  40  vertically overlaps with the fuel tank  26  so as to transverse in the front/rear direction. 
     The ventilation duct  40  is provided for passage of cooling air to the charger  33  the temperature of which rises when the charger  33  enclosed in the housing  29  having the internal space  28  is operated. 
     The first cover member  38  is bent so that its front edge portion lies along the rising portion  35  of the rear floor panel  21 . An opening is formed in a front edge surface (vertical wall portion) of the rising portion  35 , thereby enabling air in the area corresponding to the passenger compartment to be communicated to the inside of the ventilation duct  40 . 
     On the other hand, the high voltage cable  32  has such a structure that it passes so as to be deviated from the opening and is not simply exposed to the area corresponding to the passenger compartment  4 . With the above construction, although the high voltage cable  32  projects slightly so as to reduce space foot space under rear seat  27 , it is set into such a range as to occupy an undercut space below the seat, thereby preventing a substantial influence from being exercised on comfort or the like. Although rigidity is inherently high owing to a circumferential frame structure of the surface of the floor  10  at the position corresponding to the rear seat  27 , it can be further increased and deformation can be suppressed. 
     Since the high voltage cable  32 , ventilation duct  40 , and first cover member  38  are suitable for almost simultaneous mounting, the cover members can be integrated as common parts, their attaching positions can be also set to common positions, with advantages for manufacture. 
     In other words, the ventilation duct  40  for controlling the temperature of the charger  33  is provided in parallel with the high voltage cable  32 . The high voltage cable  32  and the ventilation duct  40  are inserted and laid in the first cover member  38 . Structure members (the cross member, a seat portion for a hinge, and the like) provided so as to be extended in the vehicle width direction Y in order to fix the seat are provided under the rear seat  27 . The high voltage cable  32  and the ventilation duct  40  are arranged so as to be sandwiched between them. 
     At a position at the vehicle rear side of the fuel tank  26 , the battery  25  is arranged over the rear floor panel  21  and substantially over the charger  33 . The battery  25  is a battery pack made up in such a manner that battery trains which are supported by battery frames and are arranged in a flat shape in the vertical direction are stacked vertically, or may be a high voltage battery. The battery  25  is attached so that its longitudinal direction coincides with the vehicle width direction and can be enclosed in a range comprised between the pair of right and left side frames  9 . 
     Equipment and a battery for auxiliary apparatus (low voltage battery) are arranged and attached at adjacent positions which face both edges in the longitudinal direction of the battery  25  by making use of a space between the battery and wheel housings. 
     A DC/DC converter is assembled to an upper portion of the battery  25 . A crushable protective member is provided behind the battery  25  so as to cover its rear surface. 
     The battery  25  and the charger  33  have cooling fans for temperature control and also have a ventilation duct structure for controlling temperature which is used to introduce air at a low temperature such as inside air and to mainly cool a controller (circuit board) of each battery (unit cell) and charger  33 . 
     The ventilation duct  40  which is arranged in the first cover member  38  may be replaced by a ventilation duct which is directly connected to the battery  25 . 
     As illustrated in  FIG. 4 , in the outside-car route R 2 , the high voltage cable  32  is covered with a second cover member (protective cover)  41  attached to the lower surface of the front floor panel  20 . 
     Further, a front portion of the outside-car route R 2  of the high voltage cable  32  is covered with a third cover member (protective cover)  42 , passes through a region near the steering wheel attaching portion  23 , and is extended toward the vehicle front portion. 
     Thus, in the invention according to claim  1 , the high voltage cable  32  is arranged at a position over the rear floor panel  21  which vertically overlaps with the fuel tank  26  at a central portion thereof in the vehicle width direction Y so as to lie substantially along the front/rear center axis  1 C of the vehicle  1 . The high voltage cable  32  is arranged in such a manner that ahead of the position where the cable overlaps the fuel tank  26 , the cable enters the area corresponding to the passenger compartment  4  leaving the standard surface F 2  of the rear floor panel  21 , and in front thereof, the cable passes through a region below the standard surface F 1  of the floor panel  20 . 
     As a result, the high voltage cable  32  can be arranged at a position which is sufficiently away from the side and rear surfaces of the vehicle. As illustrated in  FIG. 1 , the possibility of the cable suffering from the influence of an external force and the resulting vehicle body deformation P can be considerably reduced. At the same time, the high voltage cable  32  can be isolated also from the fuel tank  26  and the possibility of secondary damage being caused can be also extremely reduced. Further, the length of high voltage cable  32  which is exposed to the outside under the floor panel  10  is decreased and direct damage brought about during ordinary running can be also reduced. That is, as illustrated in  FIG. 1 , the high voltage cable  32  enters the area corresponding to the passenger compartment  4  from the front side of the fuel tank  26  and when it is under the rear seat  27 , the cable  32  is arranged vertically near the vehicle center. 
     Consequently, when an external force from the side does act, since damage to the high voltage cable  32  is avoided owing to the central layout and the cable  32  does not pass through the region adjacent to the side of the fuel tank  26 , contact with the high voltage cable  32  can be reduced. 
     In the invention according to claim  2 , the high voltage cable  32  is connected to the inverter  31  attached to the vehicle at a front portion thereof, the second cover member  41  for covering the portion in the area corresponding to the passenger compartment  4  of the high voltage cable  32  is provided, and the second cover member  41  covers: the penetrating portion  36  which enters the area corresponding to the passenger compartment  4  leaving the standard surface of the rear floor panel  21  on the layout of the high voltage cable; the rising portion  35  of the rear floor panel  21 ; and the floor portion  39  corresponding to the rear seat  27 . 
     Thus, while maintaining occupation space and passenger comfort, the high voltage cable  32  is isolated and both the passengers and the high voltage cable  32  can be protected. Since direct current at almost constant voltage flows, electromagnetic influence on the inside of the passenger compartment  4  is also small. 
     Further, in the invention according to claim  3 , the ventilation duct  40  for temperature control of charger  33  is provided in parallel with the high voltage cable  32 . The high voltage cable  32  and the ventilation duct  40  are inserted and laid in the second cover member  41 . 
     Thus, since the high voltage cable  32 , ventilation duct  40 , and cover member  41  can be constructed as common parts, not only the number of parts can be reduced but also they can be almost simultaneously mounted with convenience for manufacture. 
     In the embodiment described, under the rear seat, if the high voltage cable and the resin duct for cooling the charger are arranged centrally in parallel and the two parts of the high voltage cable and the ventilation duct are protected from the rear seat by a sheet metal cover, there is no need to respectively set the seat metal cover which covers the high voltage cable and the resin duct for cooling the charger. The number of parts can be reduced. 
     Additionally, by integrating the engine generator unit and the drive motor gear casing unit, these can be mounted so as to have a compact size. However, since the driving power is not propagated, it is not always necessary to mechanically couple them but the on-vehicle unit can be also made up by the drive motor and the gear casing. 
     In the layout structure of the high voltage cable according to the invention, a hybrid electric vehicle of the so-called series type has been illustrated as an example. However, if the casing of the drive motor for generating the propulsion of the vehicle and the gear casing made up by the reduction gear are arranged so as to be similarly mounted in the space ahead of the dash panel, the invention can be also applied to a purely electric vehicle, or to hybrid vehicles using other driving systems (parallel system, split system, and the like). 
     LIST OF REFERENCE NUMERALS 
     
         
         
           
               1 . Vehicle 
               2 . Vehicle body 
               3 . Engine compartment 
               4 . Area corresponding to passenger compartment 
               5 . Luggage compartment 
               10 . Floor panel 
               11 . Dash panel 
               12 . On-vehicle unit 
               13 . Engine generator unit 
               14 . Drive motor gear casing unit 
               15 . Engine 
               16 . Generator 
               17 . Drive motor 
               18 . Gear casing 
               20 . Front floor panel 
               21 . Rear floor panel 
               22 . Central tunnel 
               24 . Exhaust pipe 
               25 . Battery 
               26 . Fuel tank 
               27 . Rear seat 
               29 . Housing 
               30 . High voltage energy system 
               31 . Inverter 
               32 . High voltage cable 
               33 . Charger 
               35 . Rising portion 
               36 . Penetrating portion 
               37 . Grommet 
               38 . First cover member 
               39 . Floor portion corresponding to the rear seat 
               40 . Ventilation duct 
               41 . Second cover member 
               43 . Third cover member