The use of generally available materials for the electromagnetic steel sheets in a new motor for a one-motor SPORT HYBRID i-DCD has reduced costs, while the application of heavy rare earth-free magnets has assisted in the avoidance of procurement risk. The thickness of the steel sheets employed in the stator cores was increased from the previous 0.25 mm to 0.35 mm. The increased loss resulting from increased sheet thickness was responded to by modifying the number and position of the caulking dowels used in each stator core in order to reduce eddy current. Iron loss has also been reduced by machining corrugations into the inner circumference of the stator holder in order to reduce the contact area and thus reduce residual stress from press-fitting. In order to help ensure magnet heat resistance with the application of heavy rare earth-free magnets, the configuration of the magnets was changed from a parallel configuration to a V-shaped configuration fitted deep inside the inner circumference of the annulus formed by the rotor cores. In addition to this, the number of divisions of each magnet was changed from four divisions arrayed in the axial direction to two divisions arrayed in the circumferential direction, simplifying the production procedure and helping to realize a level of loss equivalent to that of the previous motor.
Article of Honda R&D Technical Review Vol.29 No.2 (57 - 63)