Power and control assembly for an electric drive apparatus

Abstract

A drive includes an electric motor disposed in a housing and driving a motor shaft, a Hall effect sensor adjacent to the motor, a power and control assembly, and a pinion gear driven by the motor shaft. A planetary gear reduction assembly is driven by the pinion gear, and an output axle has an axis of rotation that is offset from and parallel to the motor shaft axis of rotation. The reduction drive is substantially bilaterally symmetrical about a plane passing through the motor shaft axis of rotation and the output axle axis of rotation. The power and control assembly comprises a control board oriented perpendicular to a power board and includes a heat dissipation apparatus that applies multi-point, localized, indirect pressure to a plurality of field effect transistors mounted on the power board.

What is claimed is: 
     
         1 . A drive assembly, comprising:
 a center housing having a first side and a second side opposite the first side;   a motor housing secured to the first side of the center housing;   an axle housing secured to the second side of the center housing;   an electric motor disposed in the motor housing and configured to drive a motor output shaft having a first axis of rotation;   a pinion gear disposed in the center housing and engaged to and driven by the motor output shaft; and   a planetary gear reduction assembly comprising a plurality of planetary gears, disposed in a portion of the axle housing and a portion of the center housing, and driven by the pinion gear.   
     
     
         2 . The drive assembly of  claim 1 , further comprising an electrically conductive access cover attached to the center housing. 
     
     
         3 . The drive assembly of  claim 2 , further comprising a CAN Bus connector, a brake connector, and DC power terminals that are arranged on the access cover. 
     
     
         4 . The drive assembly of  claim 3 , wherein the DC power terminals are insulated and sealed by respective elastomeric grommets and separated by a non-conductive isolator. 
     
     
         5 . The drive assembly of  claim 4 , wherein the elastomeric grommets sealingly engage the non-conductive isolator and the access cover. 
     
     
         6 . The drive assembly of  claim 1 , further comprising:
 a bearing pocket on the first side of the center housing; and   a bearing disposed in the bearing pocket to support the motor output shaft.   
     
     
         7 . The drive assembly of  claim 6 , further comprising a Hall Effect sensor connected to a portion of the bearing pocket and disposed adjacent to a rotor of the electric motor. 
     
     
         8 . The drive assembly of  claim 1 , further comprising an electric brake attached to a distal side of the motor housing and engaged to the motor output shaft. 
     
     
         9 . A drive assembly, comprising:
 a center housing having a first side and a second side opposite the first side;   a motor housing secured to the first side of the center housing;   an axle housing secured to the second side of the center housing;   a power and control assembly comprising:
 a power board; 
 a control board; 
 a plurality of board connectors configured to connect the control board to the power board such that the control board is in a perpendicular orientation relative to the power board; 
 a plurality of support posts mounted to the power board and configured to support the control board in the perpendicular orientation; and 
 a plurality of retention clips configured to retain the control board in position; and 
   an electric motor that is disposed in the motor housing, electrically coupled to the power and control assembly, and configured to drive a motor output shaft.   
     
     
         10 . The drive assembly of  claim 9 , further comprising an electrical access chamber and a conductor chamber formed on the first side of the center housing and connected to each other by a conductor passage to accommodate the power and control assembly. 
     
     
         11 . The drive assembly of  claim 9 , wherein the control board is electrically connected to the power board. 
     
     
         12 . The drive assembly of  claim 9 , wherein the power and control assembly further comprises a plurality of field effect transistors mounted on the power board. 
     
     
         13 . The drive assembly of  claim 12 , wherein the power and control assembly further comprises a thermal pad positioned between and contacting the plurality of field effect transistors and the center housing. 
     
     
         14 . The drive assembly of  claim 13 , wherein the power and control assembly further comprises a compression assembly configured to apply pressure to the plurality of field effect transistors by compressing the plurality of field effect transistors against the thermal pad. 
     
     
         15 . The drive assembly of  claim 14 , wherein the compression assembly is configured to apply the pressure in an indirect, multi-point, and localized manner at each of the plurality of field effect transistors. 
     
     
         16 . The drive assembly of  claim 14 , wherein the compression assembly comprises a compression bridge having a plurality of spring pockets formed on a first side and a plurality of projections formed on a side opposite the first side. 
     
     
         17 . The drive assembly of  claim 16 , wherein the plurality of projections are configured to apply the pressure in an indirect, multi-point, and localized manner to a side of the power board opposite the plurality of field effect transistors. 
     
     
         18 . The drive assembly of  claim 17 , wherein the compression assembly further comprises:
 a spring retention bar; and   a plurality of compression springs nested in the plurality of spring pockets and interposed between the compression bridge and the spring retention bar.   
     
     
         19 . The drive assembly of  claim 9 , wherein the power board comprises a plurality of capacitors arranged in bilateral symmetry about a plane passing through an axis of rotation of the motor output shaft. 
     
     
         20 . The drive assembly of  claim 19 , wherein the plurality of board connectors, the plurality of support posts, and the plurality of retention clips are cooperatively positioned and arranged in bilateral symmetry about the plane.