Prevention of Premature Failure of Electric Motors in Proximity to Lubricants 2011-01-0207
Small electric DC (Direct Current) motors used to actuate various mechanisms in vehicles have failed prematurely when exposed to some formulations of lubricants, which leached into the motor and caused shorting.
The subject study explored this failure mechanism in detail as evidenced in vehicle power door lock actuators.
Experiments were conducted through the application of various types of lubricants to motors in varying ways to re-create the failure mode experienced by the authors, and to determine an optimized selection of lubricant for maximized cycle life, robust to inherent component manufacturing process variation in both the amount and location of lubrication placement.
The detailed data, photographs and conclusions which resulted were summarized. The electric motor failure mode experienced in the example situation was first explained and illustrated with detailed photography. Then, the experimentation set up and test execution used to initially recreate the failure mode and then evaluate possible solutions, including the specific motor cycle count and current trace data from the testing, with various types and applications of lubricants, was reviewed.
Finally, suggestions for alternative design and manufacturing process solutions, such as motor placement/orientation/shielding and rigorous process control for the grease application, were discussed, as further means of improving design and manufacturing process robustness to prevent the issue.