Recent commercial free-piston engine developments for automotive applications

Hanipah, Mohd Razali; Mikalsen, R.; Roskilly, Anthony Paul

doi:10.1016/j.applthermaleng.2014.09.039

Cited by 108 publications

(52 citation statements)

References 46 publications

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“…Considering the above, the determination of the piston velocity needs comprehensive consideration. However, we can give an acceptable value as our design limit referencing similar design specifications and empirical data [12,22,24]. In this work, the velocity is expected to be no higher than 12 m/s in the expansion-generating stroke, and less than 7 m/s in the compression-generating stroke.…”

Section: Energy and Efficiency Distribution Within A Single Operationmentioning

confidence: 99%

Decoupling Design and Verification of a Free-Piston Linear Generator

et al. 2016

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This paper proposes a decoupling design approach for a free-piston linear generator (FPLG) constituted of three key components, including a combustion chamber, a linear generator and a gas spring serving as rebounding device. The approach is based on the distribution of the system power and efficiency, which provides a theoretical design method from the viewpoint of the overall power and efficiency demands. The energy flow and conversion processes of the FPLG are analyzed, and the power and efficiency demands of the thermal-mechanical and mechanical-electrical energy conversion are confirmed. The energy and efficiency distributions of the expansion and compression strokes within a single stable operation cycle are analyzed and determined. Detailed design methodologies of crucial geometric dimensions and operational parameters of each key component are described. The feasibility of the proposed decoupling design approach is validated through several design examples with different output power.

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Section: Energy and Efficiency Distribution Within A Single Operationmentioning

confidence: 99%

Decoupling Design and Verification of a Free-Piston Linear Generator

et al. 2016

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“…  N+OH NO+H (9) This reaction mechanism considers the effect of oxygen, nitrogen and hydrogen radicals on NO formation, and all of the three chemical reactions have been proven to exhibit strong temperature dependency. Figure 15 illustrates the in-cylinder gas temperature field and the NO formation field at varied equivalent crank angles.…”

Section: No Emissionmentioning

confidence: 99%

“…However, the free-piston engine applications including the FPLG underwent a slow development in the early stages and reached stagnation in the 1960s due to the limitations of various factors [8]. In recent years, as an alternative power device for hybrid electric vehicles, the FPLG has attracted increasing interests from worldwide researchers [9]. With the development of the computer control technology, the internal combustion engine technology and material science, significant progress has been made in aspects of the FPLG simulation, experimental techniques, as well as the FPLG control system.…”

Section: Introductionmentioning

confidence: 99%

Research on the Combustion Characteristics of a Free-Piston Gasoline Engine Linear Generator during the Stable Generating Process

et al. 2016

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The free-piston gasoline engine linear generator (FPGLG) is a new kind of power plant consisting of free-piston gasoline engines and a linear generator. Due to the elimination of the crankshaft mechanism, the piston motion process and the combustion heat release process affect each other significantly. In this paper, the combustion characteristics during the stable generating process of a FPGLG were presented using a numerical iteration method, which coupled a zero-dimensional piston dynamic model and a three-dimensional scavenging model with the combustion process simulation. The results indicated that, compared to the conventional engine (CE), the heat release process of the FPGLG lasted longer with a lower peak heat release rate. The indicated thermal efficiency of the engine was lower because less heat was released around the piston top dead centre (TDC). Very minimal difference was observed on the ignition delay duration between the FPGLG and the CE, while the post-combustion period of the FPGLG was significantly longer than that of the CE. Meanwhile, the FPGLG was found to operate more moderately due to lower peak in-cylinder gas pressure and a lower pressure rising rate. The potential advantage of the FPGLG in lower NO x emission was also proven with the simulation results presented in this paper.

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“…Free-piston linear generators (FPLGs) are believed to be promising alternative hybrid power systems for hybrid electric vehicles (HEVs) due to their potential advantages of high-efficiency, low emissions and various fuel flexibility [1][2][3]. Because of the elimination of the crankshaft and flywheel mechanism, the compression ratio of FPLG is adjustable.…”

Section: Introductionmentioning

confidence: 99%

Hybrid System Modeling and Full Cycle Operation Analysis of a Two-Stroke Free-Piston Linear Generator

et al. 2017

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Free-piston linear generators (FPLGs) have attractive application prospects for hybrid electric vehicles (HEVs) owing to their high-efficiency, low-emissions and multi-fuel flexibility. In order to achieve long-term stable operation, the hybrid system design and full-cycle operation strategy are essential factors that should be considered. A 25 kW FPLG consisting of an internal combustion engine (ICE), a linear electric machine (LEM) and a gas spring (GS) is designed. To improve the power density and generating efficiency, the LEM is assembled with two modular flat-type double-sided PM LEM units, which sandwich a common moving-magnet plate supported by a middle keel beam and bilateral slide guide rails to enhance the stiffness of the moving plate. For the convenience of operation processes analysis, the coupling hybrid system is modeled mathematically and a full cycle simulation model is established. Top-level systemic control strategies including the starting, stable operating, fault recovering and stopping strategies are analyzed and discussed. The analysis results validate that the system can run stably and robustly with the proposed full cycle operation strategy. The effective electric output power can reach 26.36 kW with an overall system efficiency of 36.32%.

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Recent commercial free-piston engine developments for automotive applications

Cited by 108 publications

References 46 publications

Decoupling Design and Verification of a Free-Piston Linear Generator

Decoupling Design and Verification of a Free-Piston Linear Generator

Research on the Combustion Characteristics of a Free-Piston Gasoline Engine Linear Generator during the Stable Generating Process

Hybrid System Modeling and Full Cycle Operation Analysis of a Two-Stroke Free-Piston Linear Generator

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