Abstract:
A system for a vehicle may include a vehicle chassis, an electric motor, and a torque strut. The electric motor may include a rotor and may be operable in a first mode to rotate the rotor in a first direction to propel the vehicle about a rotational axis and in a second mode in which the rotor is rotated in a second direction about the rotational axis. The torque strut may include first, second and third mounting structures. The first mounting structure may be coupled to the vehicle chassis. The second and third mounting structures may be spaced apart from each other and may be coupled to the electric motor to prevent relative rotation between the torque strut and the electric motor.

Description:
FIELD 
       [0001]    The present disclosure relates to a torque strut for coupling an electric motor to a vehicle chassis. 
       BACKGROUND 
       [0002]    A vehicle powertrain component such as an engine or motor may tend to roll as a result of a moment caused by torque output of the engine or motor. A torque strut may be used to couple the engine or motor to a vehicle chassis or structural component of the vehicle and react the moment to improve the driver&#39;s comfort and feel of the vehicle during vehicle operation. 
       SUMMARY 
       [0003]    In one form, the present disclosure provides a vehicle system that may include a vehicle chassis, an electric motor, a motor bracket, and a torque strut. The electric motor may include a rotor and may be operable in a first mode to rotate the rotor in a first direction about a rotational axis and in a second mode in which the rotor is rotated in a second direction about the rotational axis. The motor bracket may be attached to the electric motor and may include first and second attachment interfaces. The torque strut may include a body and first, second and third bushings. The first, second and third bushings may each include a mounting aperture having a longitudinal axis that is parallel to the rotational axis of the rotor. The first bushing may be disposed at a first end portion of the body and may be attached to the vehicle chassis. The second bushing may be disposed at a second end portion of the body and may be attached to the first attachment interface of the motor bracket. The third bushing may be disposed between the first and second bushings and may be attached to the second attachment interface of the motor bracket. 
         [0004]    In some embodiments, the body may be a monolithic body. 
         [0005]    In some embodiments, the torque strut may be attached to the vehicle chassis only at the first bushing. 
         [0006]    In some embodiments, a center-of-mass of the torque strut may be disposed between the first and third bushings. 
         [0007]    In some embodiments, the first bushing may include a larger diameter than the second and third bushings. 
         [0008]    In some embodiments, rotation of the rotor in the second direction may produce electrical energy. 
         [0009]    In some embodiments, the body of the torque strut may be formed from a metallic material and the first, second and third bushings are formed from a polymeric material. In some embodiments, the first, second and third bushings may be formed from a metallic material. 
         [0010]    In some embodiments, the first bushing may include a plurality of openings arranged around the mounting aperture of the first bushing. 
         [0011]    In some embodiments, the torque strut may be tuned to reduce noise generated by the electric motor. 
         [0012]    In some embodiments, the second and third bushings may be configured to react a first moment generated by the electric motor when the electric motor is operating in the first mode and a second moment generated by the electric motor when the electric motor is operating in the second mode. The first and second moments may be in opposite directions. 
         [0013]    In another form, the present disclosure provides a system for a vehicle that may include a vehicle chassis, an electric motor, and a torque strut. The electric motor may include a rotor and may be operable in a first mode to rotate the rotor in a first direction to propel the vehicle about a rotational axis and in a second mode in which the rotor is rotated in a second direction about the rotational axis. The torque strut may include first, second and third mounting structures. The first mounting structure may be coupled to the vehicle chassis. The second and third mounting structures may be spaced apart from each other and may be coupled to the electric motor to prevent relative rotation between the torque strut and the electric motor. 
         [0014]    In some embodiments, the second and third mounting structures may be configured to react a first moment generated by the electric motor when the electric motor is operating in the first mode and a second moment generated by the electric motor when the electric motor is operating in the second mode. The first and second moments may be in opposite directions. 
         [0015]    In some embodiments, the torque strut may be attached to the vehicle chassis only at the first mounting structure. 
         [0016]    In some embodiments, the electric motor may be mounted to a motor bracket. The torque strut may be attached to the motor bracket only at the second and third mounting structures. 
         [0017]    In some embodiments, the torque strut may be tuned to reduce noise generated by the electric motor. 
         [0018]    In some embodiments, the first, second and third mounting structures may include first, second and third bushings, respectively. 
         [0019]    In some embodiments, the first bushing may include a larger diameter than the second and third bushings. 
         [0020]    In some embodiments, a body of the torque strut may be formed from a metallic material and the first, second and third bushings are formed from a polymeric material. In some embodiments, the first, second and third bushings may be formed from a metallic material. 
         [0021]    In some embodiments, the first bushing may include a mounting aperture and a plurality of openings arranged around the mounting aperture. 
         [0022]    In some embodiments, a center-of-mass of the torque strut may be disposed between the first and third mounting structures. 
         [0023]    In some embodiments, each of the first, second and third mounting structures may include a mounting aperture having a longitudinal axis that is parallel to the rotational axis of the rotor. 
         [0024]    In some embodiments, rotation of the rotor in the second direction may produce electrical energy. 
         [0025]    Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings provided hereinafter. It should be understood that the summary and detailed description, including the disclosed embodiments and drawings, are merely exemplary in nature intended for purposes of illustration only and are not intended to limit the scope of the invention, its application or use. Thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a perspective view of a system including a torque strut coupling an electric motor to a vehicle chassis according to the principles of the present disclosure; 
           [0027]      FIG. 2  is a side view of the torque strut and a motor bracket according to the principles of the present disclosure; 
           [0028]      FIG. 3  is a bottom view of the torque strut and motor bracket of  FIG. 2 ; 
           [0029]      FIG. 4  is a side view of the torque strut; 
           [0030]      FIG. 5  is a schematic representation of the system of  FIG. 1 ; and 
           [0031]      FIG. 6  is a graph illustrating noise improvements realized through use of the torque strut of the present disclosure relative to a prior-art torque strut. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    In an exemplary embodiment and with reference to  FIGS. 1-6 , a vehicle system  10  is provided that may include a vehicle chassis  12 , an electric motor  14 , a motor bracket  16 , and a torque strut  18 . As will be described in more detail below, the torque strut  18  couples the motor  14  to the chassis  12  in a manner that restricts or prevents relative rotation between the torque strut  18  and the motor  14  and relative rotation between the torque strut  18  and the chassis  12  while the motor  14  is operating in a propulsion mode and while the motor  14  is operating in a regenerative-braking mode. The torque strut  18  may also be tuned to reduce vibration and noise generated by operation of the motor  14 . 
         [0033]    The chassis  12  may support a vehicle suspension (not shown), a passenger compartment (not shown) of the vehicle, and a vehicle powertrain (including the motor  14 ). The chassis  12  may include a recess  20  ( FIGS. 1 and 3 ) that receives a portion of the torque strut  18  for attachment of the torque strut  18  to the chassis  12 . Mounting apertures  21  ( FIG. 3 ) may extend through the chassis  12  and into the recess  20 . 
         [0034]    When the motor  14  is operating in the propulsion mode, a rotor  22  (shown schematically in  FIG. 5 ) of the motor  14  may rotate in a first direction D1 to drive wheels of the vehicle. When the motor  14  is operating in the regenerative-braking mode, the rotor  22  may rotate in a second direction D2 to slow the vehicle and generate electrical energy through a regenerative-braking process. The rotor  22  may drivingly engage gears (not shown) disposed within a gearbox  26 . 
         [0035]    The motor bracket  16  may be attached to the torque strut  18  and may support the motor  14  and the gearbox  26 . The motor bracket  16  may include a generally C-shaped arm  24  ( FIG. 2 ) to which a housing  28  of the motor  14  may be fastened. The motor bracket  16  may also include a U-shaped mounting flange  30  including first and second apertures  32 ,  34  extending therethrough. 
         [0036]    The torque strut  18  may include a body  36 , a first bushing  38 , a second bushing  40  and a third bushing  42 . The body  36  may be a monolithic body formed from a metallic material, such as steel, aluminum or any other metallic or composite material. While the body  36  is shown in the figures as including a tapered portion  44  disposed between first and second end portions  46 ,  48  of the body  36 , in some embodiments, edges  50 ,  52  of the body  36  may be substantially planar and parallel to each other between the first and second end portions  46 ,  48 . As shown in  FIGS. 2 ,  4  and  5 , one or both side faces  54  may include a recessed portion  56  disposed between the first and third bushings  38 ,  42 . 
         [0037]    The first bushing  38  may be disposed at the first end portion  46  of the body  36 . The second bushing  40  may be disposed at the second end portion  48  of the body  36 . The third bushing  42  may be disposed between the first and second bushings  38 ,  40 . The third bushing  42  may be disposed a first distance from the second bushing  40  and a second distance from the first bushing  38 . The first distance may be shorter than the second distance. As shown in  FIG. 4 , a center-of-mass  58  of the torque strut  18  may be disposed between the first and third bushings  38 ,  42 . 
         [0038]    In some embodiments, the bushings  38 ,  40 ,  42  may be integrally formed with the body  36 . In some embodiments, the bushings  38 ,  40 ,  42  may be formed separately from the body  36  and attached thereto by a press or interference fit, welding and/or any other suitable attachment method. In some embodiments, the bushings  38 ,  40 ,  42  may be formed from the same metallic material or a different metallic material as the body  36 . In some embodiments, the bushings  38 ,  40 ,  42  may be formed at least partially from a polymeric material. 
         [0039]    The first, second and third bushings  38 ,  40 ,  42  may include first, second and third mounting apertures  60 ,  62 ,  64 , respectively, extending therethrough. The mounting apertures  60 ,  62 ,  64  may have longitudinal axes that are substantially parallel to a rotational axis of the rotor  22 . The first bushing  38  may include a plurality of recesses and/or openings  65  arranged around the first mounting aperture  60 . The openings  65  may extend partially or completely through the first bushing  38 . In some embodiments, the recesses and/or openings  65  may be provided to achieve a desired mass, mass distribution and/or rigidity of the torque strut  18 . It will be appreciated that, in some embodiments, the second and/or third bushings  40 ,  42  may include recesses and/or openings. 
         [0040]    As shown in  FIG. 3 , a first fastener  66  may extend through the first mounting aperture  60  of the first bushing  38  and may be received in the mounting apertures  21  of the chassis  12  to secure the torque strut  18  to the chassis  12 . A second fastener  68  may extend through the second mounting aperture  62  of the second bushing  40  and the apertures  32  of the motor bracket  16 . The third fastener  70  may extend through the third mounting aperture  64  of the third bushing  42  and the apertures  34  of the motor bracket  16 . The fasteners  66 ,  68 ,  70  may be or include pins, rivets or bolts, for example, and/or any other fastening devices. As shown in  FIG. 3 , nuts  72  may engage the fasteners  66 ,  68 ,  70  to retain the fasteners  66 ,  68 ,  70  within the bushings  38 ,  40 ,  42 . 
         [0041]    While not shown in the drawings, it will be appreciated that other struts, brackets and/or other support structures may be provided in addition to the torque strut  18  to secure the motor  14  and/or the motor bracket  16  relative to the chassis  12 . 
         [0042]    As described above, the torque strut  18  couples the motor  14  to the chassis  12  in a manner that restricts or prevents relative rotation between the torque strut  18  and the motor  14  and relative rotation between the torque strut  18  and the chassis  12  while the motor  14  is operating in the propulsion mode and while the motor  14  is operating in the regenerative-braking mode. When the motor  14  is operating in the propulsion mode (i.e., when the rotor  22  is rotating in the first direction D1), a first reaction moment is generated in a direction opposite to the first direction D1 that biases the motor housing  28  in the second direction D2 relative to the torque strut  18  and chassis  12 . When the motor  14  is operating in the regenerative-braking mode (i.e., when the rotor  22  is rotating in the second direction D2), a second reaction moment is generated in a direction opposite to the second direction D2 that biases the motor housing  28  in the first direction D1 relative to the torque strut  18 . Because the motor bracket  16  (which is rigidly coupled to the motor  14  at a plurality of locations) is attached to the torque strut  18  at two locations—namely, the second and third bushings  40 ,  42 —the motor bracket  16  (and hence, the motor  14 ) are restricted or prevented from rotating relative to the torque strut  18  and chassis  12  during either operating mode of the motor  14 . That is, the second and third bushings  40 ,  42  react the moments generated during the propulsion mode and the regenerative-braking mode. 
         [0043]    As described above, the torque strut  18  may be tuned to reduce vibration and noise generated during operation of the motor  14 . That is, connection of the torque strut  18  to the motor bracket  16  at two locations (i.e., at the second and third bushings  40 ,  42 ) as well as the rigidity of the body  36  of the torque strut  18  may isolate the chassis  12  from relatively high-frequency vibration generated by the motor  14 . This vibration isolation may reduce noise audible to people in the passenger compartment of the vehicle and reduce vibrations that can be felt during operation of the vehicle, thereby improving driver and passenger enjoyment and perception of quality. 
         [0044]      FIG. 6  illustrates the improvement in noise reduction due to implementation of the torque strut  18  of the present disclosure relative to a system having a prior-art torque strut. In the graph of  FIG. 6 , the solid line represents noise versus frequency or operating speed of the motor  14  for the system  10  of the present disclosure. The dashed line in the graph of  FIG. 6  represents noise versus frequency or operating speed of the motor for a system having a prior-art torque strut. As shown in  FIG. 6 , implantation of the torque strut  18  of the present disclosure results in a reduction of noise over nearly the entire range of frequencies between 318 Hz and 1250 Hz.