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Journal Article

The Performance Characteristics of an Production Oriented Air Hybrid Powertrain

2010-04-12
2010-01-0821
In a previous paper [ 1 ], the authors have proposed a cost effective air hybrid concept based on a proprietary intake system and cam profile switching (CPS) system [ 2 ]. It was shown through engine simulations that the pneumatic hybrid operation could be achieved with about 15% regenerative efficiency. The proposed air hybrid operation can be achieved with proven technologies and engine components and hence it represents a cost-effective, reliable and quick deployable solution for low carbon vehicles. In this work, a four-cylinder 2 litre diesel engine has been modelled to operate on refined air hybrid engine configurations and the braking and motoring performance of each configuration have been studied. Both air hybrid systems can be constructed with production technologies and incur minimum changes to the existing engine design.
Technical Paper

Control of CAI Combustion Through Injection Timing in a GDI Engine With an Air- Assisted Injector

2005-04-11
2005-01-0134
Controlled auto Ignition (CAI) combustion has great potential for reducing both NOx emissions and fuel consumption in IC engines and the application of direct injection technology to the CAI engine adds another dimension of control to the combustion process. In this work an air-assisted injection system was applied to an engine that used residual gas to initiate and control CAI combustion. Injections were performed at Exhaust valve closure (EVC), intake valve opening (IVO) and BDC of the intake/compression stroke and the effects on combustion phasing (i.e. ignition timing and burn duration), engine output, fuel consumption and exhaust emissions analyzed. Injection at EVC gave the best results in terms of engine output, operating range and combustion stability. Injection at IVO generally resulted in the lowest fuel consumption. It was found that injection timing is an effective means of controlling combustion phasing.
Technical Paper

2-Stroke CAI Operation on a Poppet Valve DI Engine Fuelled with Gasoline and its Blends with Ethanol

2013-04-08
2013-01-1674
Controlled Auto Ignition (CAI), also known as Homogeneous Charge Compression Ignition (HCCI), is one of the most promising combustion technologies to reduce the fuel consumption and NOx emissions. Currently, CAI combustion is constrained at part load operation conditions because of misfire at low load and knocking combustion at high load, and the lack of effective means to control the combustion process. Extending its operating range including high load boundary towards full load and low load boundary towards idle in order to allow the CAI engine to meet the demand of whole vehicle driving cycles, has become one of the key issues facing the industrialisation of CAI/HCCI technology. Furthermore, this combustion mode should be compatible with different fuels, and can switch back to conventional spark ignition operation when necessary. In this paper, the CAI operation is demonstrated on a 2-stroke gasoline direct injection (GDI) engine equipped with a poppet valve train.
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