Cold start characteristics at misplaced ignition strategy on the first firing cycle of a dual cylinder linear range extender

The free piston linear range extender (LRE) system is a promising technology for alleviating range anxiety in electric vehicles. In this research, an innovative cold-start optimization method based on ignition phase control is proposed. The effects of the same phase, the phase advance and the phase lag ignition strategies on the cold-start characteristics of the system during the first firing cycle are systematically investigated. Results show that delaying ignition under the same phase strategy significantly improves system performance, increasing operating frequency by 1.10Hz, enhancing thermal efficiency by 7.16 %, and boosting indicated power by 0.65 kW. Maintaining one ignition position constant, the phase advance strategy yields comparatively lower performance, while a suitable phase lag strategy increases operating frequency by 0.25Hz, improves thermal efficiency by 0.76 %, and enhances indicated power by 0.06 kW. Analysis reveals that the appropriate same phase strategy optimizes thermal efficiency and indicated work, while the suitable out-of-phase strategy enhances operating frequency and indicated power. Therefore, flexible selection between the same phase or the phase lag ignition strategies during the cold start phase of the LRE system can optimize system performance and cold start effects.