Reducing Starting Current for Existing Commercial Vehicle Engines

In present commercial vehicles, the cranking torque required for a heavy duty compression ignition engine is very high. This results in higher durability and reliability requirement of cranking system components and also makes it cumbersome to implement start-stop micro hybrid feature which requires more number of cranking cycles in lifetime. Hence higher capacity starter motor and battery is being used for implementing start-stop feature. However this would result in cost and packaging issues. In order to implement start-stop feature maintaining the same starter motor and battery capacity, the cranking energy demand of the engine needs to be reduced. Studies conducted shows that the major source of breakaway torque is the work done in compression stroke during a starting cycle. Hence the concept of decompression which is used only in smaller capacity engines at present was benchmarked and modified to create an energy venting actuator for a heavy duty 4 cylinder engine which would release the compression pressure momentarily during starting. The cranking torque requirement for the engine was analyzed with and without the decompression device and an experimental reduction of 29% in starting current requirement was obtained.