Effects of spark-assistance on controlled auto-ignition combustion at different injection timings in a multicylinder direct-injection gasoline engine

2009 ◽  
Vol 10 (3) ◽  
pp. 133-148 ◽  
Author(s):  
N Kalian ◽  
H Zhao ◽  
C Yang
Author(s):  
Y Li ◽  
H Zhao ◽  
N Brouzos ◽  
B Leach

Controlled auto-ignition (CAI) combustion in gasoline engines has great potential for reducing both NO x emissions and fuel consumption, but its application is still hindered by the lack of direct control of combustion phasing and by the limited CAI operation range. In this paper, the effect of injection timing and split injection on CAI combustion is presented in a single-cylinder direct-injection gasoline engine with an air-assisted injector. The CAI combustion was achieved by trapping some of the burned gases within the cylinder by using low-lift short-duration camshafts and early closure of the exhaust valves. During the experiments, the engine speed was varied from 1200 to 2400 r/min and the air-fuel ratio was altered from stoichiometric to the misfire limit. Both single and split injections were investigated at different injection timings and fuel quantities. The experimental results show that injection timing has an important effect on CAI combustion for single and split injections. Early injection produces faster and more stable combustion, less hydrocarbon and CO emissions, but very rapid heat release rates and higher NO x emissions. The CAI operation range could be extended significantly by early injection. Split injection gives even further extension of the CAI range in both stoichiometric and lean mixture operations. These results indicate that optimizing the injection timing and using split injection is an effective way to control and extend CAI operation in a direct-injection gasoline engine.


Author(s):  
N Kalian ◽  
H Zhao ◽  
J Qiao

Controlled auto-ignition (CAI) combustion, also known as homogeneous charge compression ignition (HCCI), can be achieved by trapping residuals with early exhaust valve closure in a direct-fuel-injection in-cylinder four-stroke gasoline engine (through the employment of low-lift cam profiles). Because the operating region is limited to low-load and midload operation for CAI combustion with a low-lift cam profile, it is important to be able to operate spark ignition (SI) combustion at high loads with a normal cam profile. A 3.0l prototype engine was modified to achieve CAI combustion, using a cam profile switching mechanism that has the capability to switch between high- and low-lift cam profiles. A strategy was used where a high-lift profile could be used for SI combustion and a low-lift profile was used for CAI combustion. Initial analysis showed that for a transition from SI to CAI combustion, misfire occurred in the first CAI transitional cycle. Subsequent experiments showed that the throttle opening position and switching time could be controlled to avoid misfire. Further work investigated transitions at different loads and from CAI to SI combustion.


2000 ◽  
Vol 1 (2) ◽  
pp. 147-161 ◽  
Author(s):  
J Reissing ◽  
H Peters ◽  
J. M. Kech ◽  
U Spicher

Gasoline direct injection (GDI) spark ignition engine technology is advancing at a rapid rate. The development and optimization of GDI engines requires new experimental methods and numerical models to analyse the in-cylinder processes. Therefore the objective of this paper is to present numerical and experimental methods to analyse the combustion process in GDI engines. The numerical investigation of a four-stroke three-valve GDI engine was performed with the code KIVA-3V [1]. For the calculation of the turbulent combustion a model for partially premixed combustion, developed and implemented by Kech [4], was used. The results of the numerical investigation are compared to experimental results, obtained using an optical fibre technique in combination with spectroscopic temperature measurements under different engine conditions. This comparison shows good agreement in temporal progression of pressure. Both the numerical simulation and the experimental investigation predicted comparable combustion phenomena.


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