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Engine systems
Published in Tom Denton, Advanced Automotive Fault Diagnosis, 2020
For optimum efficiency, the ignition advance angle should be such as to cause the maximum combustion pressure to occur approximately 10° after TDC. The ideal ignition timing is dependent on two main factors: engine speed and engine load. An increase in engine speed requires the ignition timing to be advanced. The cylinder charge, of air fuel mixture, requires a certain time to burn (normally approximately 2 ms). At higher engine speeds, the time taken for the piston to travel the same distance reduces. Advancing the time of the spark ensures that full burning is achieved.
Engines
Published in Tom Denton, Alternative Fuel Vehicles, 2018
For optimum efficiency the ignition advance angle should be such as to cause the maximum combustion pressure to occur at about 10° after TDC. The ideal ignition timing is dependent on two main factors, engine speed and engine load. An increase in engine speed requires the ignition timing to be advanced. The cylinder charge, of air fuel mixture, requires a certain time to burn (about 2 ms). At higher engine speeds the time taken for the piston to travel the same distance reduces. Advancing the time of the spark ensures full burning is achieved.
Ignition and starter systems
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
This can range from a chalky white core nose colouring and excessive electrodes erosion, to burnt electrodes and a blistered or split core nose, according to the severity of overheating. These conditions are associated with over-advanced ignition timing, a fuel with insufficient octane rating, a too weak mixture or a defective engine cooling system, all of which can lead to excessive detonation and pre-ignition.
Performance comparison of biomethane, natural gas and gasoline in powering a pickup truck
Published in Biofuels, 2022
Pruk Aggarangsi, James Moran, Sirichai Koonaphapdeelert, Nakorn Tippayawong
The first item was to quantify was the effect of the Air/Fuel stoichiometric ratio on the engine power and torque. For this purpose, an A/F meter from Innovate Motorsport was used along with variable ignition timing. Normally, the engine’s default Electronic Control Unit (ECU) from the factory does not allow adjustment of the ignition timing. In order to take control of the ignition timing, the default ECU was replaced with a Haltech Platinum Sports 1000 model ECU. The engine performs as the original with the addition feature that the ignition timing is controlled, up to 60 degrees before top dead center. After installing the new ECU, the engine was mounted on a chassis dynamometer, in 4th gear with the throttle fully opened. The fuel used was biomethane 85%. Lambda, the real A/F ratio divided by the stoichiometric A/F ratio, was adjusted from 0.80 to 1.05 in increments of 0.05 for a total of 6 data points. These components are shown in Figure 3.
Technical barriers and their solutions for deployment of HCCI engine technologies – a review
Published in International Journal of Ambient Energy, 2021
Swapnil Sureshchandra Bhurat, Shyam Pandey, Venkateswarlu Chintala, P. S Ranjit
In conventional SI and CI engines, the combustion process is usually controlled by spark ignition and fuel injection timings respectively. In the case of HCCI engines, auto ignition of homogeneous air–fuel charge plays a vital role. In HCCI engine, ignition of the air–fuel mixture occurs at several points simultaneously and spontaneously. Accurate control of auto ignition timing is a tedious task and involves a wide range of engine operating conditions. The utmost severe problem in the HCCI engine is to control the timing of auto-ignition and subsequently the heat release rate (HRR) (Flowers et al. 2001), (Angelos et al. 2008). Hence, an adequate understanding and assessment of the ignition timing and combustion processes are must for the smooth operation of HCCI engines. HCCI does not have direct control over the combustion of charge, as it is auto-ignited. Auto-ignition of the charge depends on a number of parameters such as cylinder walls surface temperature, exhaust gas recirculation ratio, engine speed, fuel properties, and a compression ratio of the engine (Dec and Sjöberg 2004; Yao, Zheng, and Liu 2009; Chintala and Subramanian 2014a). It is noted that inadequate control of combustion phenomenon affects the engine behaviour substantially (Chintala and Subramanian 2016). For example, too early combustion leads to a decrease in thermal efficiency along with NOx emission increment. Too late combustion leads to misfire the engine and continuous repetition of misfiring leads to engine stall. Too late HCCI combustion increases the fuel consumption with the exponential rise in HC and CO emissions.
Operational feasibility of a spark ignition engine which is subjected to VTEC management strategy
Published in Australian Journal of Mechanical Engineering, 2020
Lucky Anetor, Edward E. Osakue
It is readily seen from Tables 1–4, that in order to achieve the viable engine operating characteristics shown in Figures 7–9 at the very weak intake of air-fuel mixture value of , the flame speed factor, that is, the turbulence levels had to be increased though not in direct proportion to engine speeds. This is consistent with practical engine operations, since various experimental studies Taylor (1985) and Hires, Tabaczynski, and Novak (1978) have shown that the turbulence levels in engines do increase with speed. Since the overall combustion duration, varies with engine speed, the ignition timing, of spark ignition engines is related to the engine speed either through the flywheel system or via the electronic engine management system. From the foregoing, it is easy to deduce that viable engine cycles per the VTEC engine management scheme can be achieved by advancing the ignition timing as the engine speed increases.