Development & Field Testing of Air-In-Head Starting System
Air-in-head starting of large bore internal combustion engines has been problematic due to poor reliability, high air consumption, difficulties associated with remote starting, and dead spots on some engines. This paper describes the development, flexibility, and field test of an electronic air-in-head starting system designed to overcome these problems. It represents the first major advancement in the state-of-the-art of air-in-head starting in over 30 years. The development and operation of the system, which controls both the individual cylinder crank angle that initiates air injection, and the duration or (dwell time) of the air injected into each individual power cylinder, is described. Other design goals, such as major reduction of starting air consumption, regulation of cranking rpm, elimination of dead spots, reduction of wearing parts on the engine, and the elimination of manual barring of the engine are described, as are the hardware and software approaches embodied in the system to achieve the design goals. The resulting system knows and displays crankshaft angular position both at rest and throughout the starting process. The system regulates cranking RPM at desired values by varying the duration of the air being injected into the power cylinders. Unlike ring gear start conversions the engine purge cycle is shortened by virtue of using spent air to scavenge the cylinders. Reliance on cam lobe actuated push rods is also eliminated and reduces parasitic load on the engine. Field test results of the system on a Cooper GMW-6 in mainline gas transmission service shows up to 70% reduction in starting air consumption are also presented.