Abstract:
A high power cable ( 53 A,  53 B) connects an electric terminal ( 51 A,  51 B) of a transaxle case ( 45 ) housing an electric motor ( 4 ) coupled to a drive shaft S and an electric terminal ( 52 A,  52 B) of an inverter housing ( 40 ) which supplies power to the electric motor ( 4 ) in a hybrid drive vehicle. A holder ( 54 A,  54 B) is provided which holds the high power cable ( 53 A,  53 B) in a curved shape in the axial direction of the drive shaft. The holder ( 54 A,  54 B) releases the high power cable ( 53 A,  53 B) when a predetermined external force acts on the high power cable ( 53 A,  53 B) toward the front of the vehicle.

Description:
FIELD OF THE INVENTION 
     This invention relates to an arrangement of a high power cable which connects a motor and power supply devices of hybrid drive vehicles and electric drive vehicles. 
     BACKGROUND OF THE INVENTION 
     A parallel hybrid vehicle which runs under the power of either the engine or the motor, or both, is disclosed in pp. 39-52 of “Automobile Engineering”, Vol. 46, No.7, published in June 1997 in Japan by Tetsudo Nihon Sha. 
     In such a hybrid vehicle, the engine and the motor are supported on the vehicle body via a relatively low rigidity mount which uses a large mass of rubber or the like to suppress transmission of vibration to the vehicle body. On the other hand, an electric power supply device is installed via a relatively high rigidity bracket on the body. Therefore, some relative movement arises between the motor and electric power supply device while the vehicle is traveling. 
     To absorb this relative motion, there must be some tolerance in the length of high power cable which supplies power from the electric power supply device to the motor. If the vehicle were to suffer an impact which did not damage the motor, but which caused a larger relative displacement than usual, it is desirable that this displacement would not damage the cable so that the vehicle could continue to run. The high power cable is therefore designed to have a length which can comply with such a necessity. 
     SUMMARY OF THE INVENTION 
     In a hybrid vehicle, in addition to an engine, a motor for running, a motor for generating power, a motor for generating oil pressure, a high output battery for driving motors, a battery for driving auxiliary devices and inverters for controlling the output of the motors, are installed in an engine room. 
     As a result, there is little space available surrounding the engine and motors, and it is difficult to provide a high power cable of sufficient length. Also, if the length of the high power cable is increased, it easily comes in contact with other instruments due to vibration when the vehicle is running, so there is a high probability that the cable will be damaged and wear out due to this contact. 
     Even in an electric drive vehicle having only a motor as source of drive force, a reaction to the motor drive force causes relative motion between the motor and power supply devices, and there is a risk that the same problem will occur as with a hybrid drive vehicle. 
     It is therefore an object of this invention to suitably arrange a high power cable which connects a motor with a power supply device in a hybrid drive vehicle or electric drive vehicle. 
     In order to achieve the above object, this invention provides an aligning device for a high power cable in such an electric drive vehicle that comprises a drive device including an electric motor coupled to a drive shaft, and a power supply device which supplies current to the electric motor via a high power cable. The aligning device comprises a holder that holds the high power cable in a curved shape in an axial direction of the drive shaft while releasing the high power cable when the high power cable is subject to a predetermined external force acting toward the front of the vehicle. 
    
    
     The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of a hybrid drive vehicle to which this invention is applied. 
     FIG. 2 is a plan view of an engine room in the hybrid drive vehicle. 
     FIG. 3 is front elevation of an inverter housing and transaxle case showing the arrangement of high power cables according to this invention. 
     FIG. 4 is a side view of the inverter housing and transaxle case showing the arrangement of the high power cables according to this invention. 
     FIG. 5 is a side view of a holder according to this invention viewed from the insertion direction of the high power cables. 
     FIG. 6 is another side view of the holder viewed at right-angles to the view of FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1 of the drawings, a parallel hybrid drive vehicle to which this invention is applied comprises an engine  2  connected to a motor  4  via a clutch  3 . When the clutch  3  is released, only the output torque of the motor  4  is transmitted to drive wheels  8  via a continuously variable transmission  5 , reduction device  6  and differential gear  7 . 
     When the clutch  3  is engaged, the output torques of both the engine  2  and motor  4  are transmitted to the drive wheels  8 . The continuously variable transmission may be a V-belt continuously variable transmission, toroidal continuously variable transmission or the like, and its speed ratio is varied continuously according to an oil pressure supplied by an oil pressure device  9 . 
     Other motors  1  and  10  are also connected to the engine  2 . 
     The motor  1  is mainly used to start the engine  2  and to generate electric power. The motor  4  is mainly used to drive the drive wheels  8  and for generating regenerative power using the braking of the vehicle. 
     Therefore, the motors  1  and  4  are motor/generators. 
     On the other hand, the motor  10  is used to drive an oil pump with which the oil pressure device  9  is provided, and it functions only as a motor. 
     The motors  1 ,  4  and  10  are alternating current motors. The operation of the motors  1 ,  4  and  10  is respectively controlled via inverters  11 ,  12  and  13 . 
     The solid line of FIG. 1 shows the transmission path of mechanical force, the broken line shows the transmission path of power, the dot-and-dash line shows the transmission path of signals, and the double line shows the transmission path of oil pressure. 
     This invention is applied to a high power cable forming a power transmission path between the motor  1 ,  4 ,  10 , and the inverters  11 ,  12 ,  13 . 
     Next, referring to FIG. 2, an engine room  44 A is formed in a vehicle body  44  which is a monocoque body. 
     An engine  2  is arranged in the engine room  44 A such that the rotation shaft of the engine  2  is perpendicular to the direction of travel of the vehicle. In addition, the motor  10 , auxiliary battery  33 , inverter housing  40 , air conditioner compressor  41 , radiator  42 , electric fan  43 , and transaxle case  45  are disposed in the engine room  44 A. 
     The transaxle case  45  is joined to one edge of the engine  2 , and comprises a drive device of the vehicle together with the engine  2 . The motor  1 , clutch  3 , motor  4 , continuously variable transmission  5  and reduction device  6  shown on FIG. 1 are built into the transaxle case  45 . The engine  2  and motor  4  are arranged coaxially via the clutch  3 . In the following description, the shaft of the motor  4  is referred to as a drive shaft S. The engine  2  and transaxle case  45  are supported in the vehicle body  44  via a low rigidity support mechanism, not shown, by a rubber mount. 
     The inverter housing  40  corresponds to an electric power supply device of the vehicle and accommodates the inverters  11 - 13  shown in FIG.  1 . The inverter housing  40  is supported in the body  44  above the transaxle case  45  via a high rigidity support mechanism, not shown. 
     Next, referring to FIGS. 3 and 4, three electric terminals  51 A and three electric terminals  51 B respectively connected to the motors  1  and  4  are provided on the outer surface of the transaxle case  45 . 
     Three electric terminals  52 A and three electric terminals  52 B are respectively arranged on the base of the inverter housing above the electric terminals  51 A and  51 B. 
     The electric terminals  52 A and  52 B are arranged in a row along the drive shaft S. In such an arrangement, it is easy to lay the high power cable in the narrow space alongside the engine  2 . 
     The electric terminals  51 A and  52 A are connected by three high power cables  53 A. The electric terminals  51 B and  52 B are connected by three high power cables  53 B. The length of the high power cables  53 A is longer than the distance between the electric terminals  51 A and  52 A, and the length of the high power cables  53 B is longer than the distance between the energizing terminals  51 B and  52 B. 
     To take up the slack in the high power cables  53 A,  53 B, the high power cables  53 A,  53 B are curved in the direction of the drive shaft S under the inverter housing  40  as shown in FIG.  3 . To arrange the high power cables  53 A,  53 B in such a curve, holders  54 A,  54 B for fixing the cables are fixed to the inverter housing  40  via brackets  46 A,  46 B. The upper parts of the power cables  53 A,  53 B are respectively fixed to predetermined positions on the base of the inverter housing  40  by the holders  54 A,  54 B. Also, the lower sides of the high power cables  53 A,  53 B are fixed to the upper surface of the transaxle case  45  by holders  54 C,  54 D. 
     Thus, the high power cables  53 A,  53 B are forcibly curved by the holders  54 A- 54 D in the direction of the drive shaft S, that is, in the transverse direction of the vehicle. This curvature absorbs the relative displacement of the transaxle case  45  and inverter housing  40  due to vehicle vibration while the vehicle is traveling, and is useful in avoiding too large a bending load acting on the connecting parts between the electric terminals  51 A,  51 B,  52 A,  52 B, and high power cables  53 A,  53 B. Since the upper parts of the high power cables are respectively fixed to the inverter housing  40  by the holders  54 A,  54 B, and the lower parts thereof are respectively fixed to the transaxle case  45  by the holders  54 C,  54 D, there is little chance that the high power cables  53 A,  53 B will come into contact with surrounding equipment due to vibration when the vehicle is running. 
     Next, the structure of the holders  54 A,  54 B,  54 C and  54 D will be described referring to FIGS. 5 and 6. 
     The holders  54 A,  54 B,  54 C,  54 D are formed of a plastic material. Since all these holders have the same structure, the holder  54 A will be taken as an example in the following description. 
     The holder  54 A is provided with three openings  55  which have effectively the same internal diameter as that of the outside diameter of the high power cable  53 A. 
     A pair of hooks  56  are respectively provided at the entrance to each of the openings  55 . When the high power cable  53 A is pressed into the holder  54 A, the high power cable  53 A is set in this opening  55  while the corresponding pair of hooks  56  are pushed apart, and the cable  53 A is thereby held inside the opening  55  by the elastic force of the hooks  56 . The holder  54 A is fixed to the inverter housing  40  via a flat bracket  46 A as shown in FIG.  3 . For this purpose, the holder  54 A is provided with two projections  57  on its base. 
     As shown in FIG. 6, the projection  57  comprises a flat spring-shaped member  57 A whereof the base end widens toward the outside in an inverted V-shape, and a rod  57 B which supports the center part of the flat spring-shaped member  57 A on the base of the holder  54 A. 
     A pair of flat legs  58  are also provided slanting downwards from both sides of the projection  57  on the base of the holder  54 A. 
     As shown in FIG. 6, two throughholes  47  of rectangular cross-section are formed in the bracket  46 A through which the projection  57  can pass. The width of the throughhole  47  is formed slightly less than the width of the base end of the flat spring-shaped member  57 A. The projection  57  is pushed into the throughhole  47  by deforming the base end of the member  57 A towards the inside. 
     The flat spring-shaped member  57 A which was pushed into the throughhole  47  then returns to its original shape, and the base end projects outside the throughhole  47 . Thereafter, the base end of the member  57 A comes in contact with the bracket  46 A surrounding the throughhole  47  if a pulling force is applied to the member  57 A, and provides a resistance to any force tending to pull out the projection  57 . Moreover, when the projection  57  is pushed into the throughhole  47 , the legs  58  elastically deform outwards from the position of the broken line to the state shown by the solid line in FIG.  6 . The holder  54 A is thus firmly fixed to the bracket  46 A by the base end of the member  57 A and the elastically deformed legs  58  which grip the bracket  46 A. The holder  54 B is fixed to the inverter housing  40  via an identical bracket  46 B. Further, the holders  54 C,  54 D, although not shown, are fixed to the crankcase  45  by an identical structure. Regarding the holders  54 A,  54 B, the shape of the brackets  46 A,  46 B and their fixing positions on the inverter housing  40  are preset so that they are fixed with the opening  55  facing the front of the vehicle. 
     If the vehicle comes in contact with another vehicle or a fixed object, for example, so that a slight collision occurs, and the vehicle suffers an impact which is not severe enough to damage the motors, the inverter housing  40  and transaxle case  45  undergo a large relative displacement due to the difference in the rigidity of the support mechanisms. When the high power cables  53 A,  53 B are pulled forward strongly by this relative displacement, the hooks  56  of the holders  54 A,  54 B elastically deform, and the high power cables  53 A,  53 B respectively separate from the holders  54 A,  54 B. As a result, since the high power cables  53 A,  53 B are free to extend further, the high power cables  53 A,  53 B do not easily become damaged or fall out from the electric terminals. Therefore, electrical connection between the electric terminals  51 A and  52 A, and electrical connection between the electric terminals  51 B and  52 B continue to be maintained even after a collision of the vehicle. 
     To maintain a predetermined curvature of the high power cables  53 A,  53 B, while suppressing the effect of vibration of the transaxle case  45  and the inverter housing  40 , it is preferable to set the restraining force on the high power cables  53 A,  53 B due to the hooks  56  to be 3-10 times the maximum value of the tractive force, compressive force or bending force on the high power cables  53 A,  53 B due to the vibration of the engine or transaxle case  45  while the vehicle is traveling. 
     On the other hand, when there is a large relative displacement between the inverter housing  40  and transaxle case  45 , in order that the holders  54 A,  54 B release the high power cables  53 A,  53 B, it is preferable to set the restraining force on the high power cables  53 A,  53 B due to the hooks  56  to lie within the range of {fraction (1/10)}-⅓ of the maximum shearing forces that the high power cables  53 A,  53 B can withstand. 
     The material and the size of the hooks  56  are designed to meet the aforesaid requirement. 
     The contents of Tokugan Hei 10-320158, with a filing date of Nov. 11, 1998 in Japan, are hereby incorporated by reference. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. 
     For example, instead of releasing the high power cables  53 A,  53 B by the deformation of the hooks  56 , it is also possible to design a system wherein the holders  54 A,  54 B separate from the brackets  46 A,  46 B when the high power cables  53 A,  53 B are strongly pulled towards the front by setting the joining force between the projections  57  and brackets  46 A,  46 B to be weaker. 
     Further, in this embodiment, the invention was applied to a hybrid vehicle, but there is a possibility that relative displacement of a motor and an electric power supply device will occur in an electric drive vehicle without an engine due to a difference in support rigidity between the motor and electric power supply device. Therefore, this invention is also effective for high power cables which connect the drive device with the power supply device of such an electric drive vehicle. 
     The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows: