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Integration of automatic engine Stop/Start systems in “conventional” drivetrains with 12V starters is a relatively cost-effective measure to reduce fuel consumption. Therefore, automatic engine Stop/Start systems are becoming more prevalent and increasing market share of such systems is predicted. A quick, reliable and consistent engine start behavior is essential for customer acceptance of these systems. The launch of the vehicle should not be compromised by the Stop/Start system, which implies that the engine start time and transmission readiness for transmitting torque should occur within the time the driver releases the brake pedal and de-presses the accelerator pedal. Comfort and NVH aspects will continue to play an important role for customer acceptance of these systems. Hence, the engine stop and re-start behavior should be imperceptible to the driver from both a tactile and acoustic standpoint.

Every automaker is looking for ways to improve the fuel economy of its vehicle fleet to meet the EPA greenhouse gas regulation, which translates into 2025 Corporate Averaged Fuel Economy of 54.5 mpg. Engine Stop Start technology will improve the fuel economy of the vehicle by shutting down the engine when the vehicle is stationary. While this is an established technology in Europe, it is beginning to gain momentum in North America, where NVH refinement is a stronger consideration. To utilize the fuel economy benefits of Stop Start technology in the North American market, the technology must be seamlessly incorporated into the vehicle. This paper gives an overview of characterizing an auto start based on the features of a few Powertrain-system-level metrics. Following the fundamentals of NVH, (Source, Path and Receiver) the receiver touch points will be less perceptible to vibration, if the powertrain-system source is made smoother.