Start-Stop Technology has become common in vehicles due to stringent government regulations with respect to emissions and fuel economy. To reduce the fuel consumption and vehicle emissions, the S-Start-stop System automatically shuts down and restarts the engine to reduce the engine idle time. However, significant jerk or forward vehicle jump can be felt inside the cabin when the driver lifts the foot from brake pedal and engine restart occurs. Since Stop-Start technology is critical for OEMs to meet the norms, solution to mitigate or eliminate the jerk feel in restart situations is the way forward. The current work describes the optimization techniques to avoid jerk during star-stop function. To avoid the jerk during engine restart, a delay in Brake pressure release is induced such that when the brake pedal is pressed the engine stops, provided all other Start-Stop conditions are met. The pressure generated at wheel ends during brake press is used to hold the vehicle for a defined time even after driver releases the brake pedal. Reduction in brake pressure can be done after the engine restart so that the vehicle starts moving slowly avoiding jerk situation. The Brake Hold function activation is done based on combination of inputs like engine rpm, brake pedal signal, etc. The function Hold times were calibrated based on the vehicle to ensure system robustness and to avoid the vehicle level jerks in the best way possible. The proposed methodology highly reduces the occurrences of vehicle jerk.
Mr. Sourav Nanda, Engineer, Mahindra Research Valley, M&M; Mr. Shivram Rajasekaran, Senior Lead Engineer, Mahindra & Mahindra Ltd.; Mr. Arunkumar Prasad, Lead Engineer, Mahindra & Mahindra Ltd.; Mr. Parthiban Ramamoorthy, Senior Lead Engineer, Mahindra & Mahindra Ltd; Mr. Nishit Goel, Senior Principal Engineer, Mahindra & Mahindra Ltd