Improving the constant‐volume degree of combustion considering generatable range at low speed in a free‐piston engine linear generator system

Sato, Masaru; Naganuma, Kaname; Nirei, Masami; Yamanaka, Yuichiro; Suzuki, Takahiro; Goto, Takumi; Bu, Yinggang; Matsumoto, Tsutomu

doi:10.1002/tee.22993

Cited by 5 publications

(5 citation statements)

References 11 publications

(14 reference statements)

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“…The electric power generated by the reciprocating motion of the mover charges the battery through the inverter. The power generation control of the inverter adjusts the power generation current, resulting in variable braking thrust F l [25,28]. FPEGs without a linear rotation conversion mechanism can easily change the stroke and frequency of piston operation by using power generation control.…”

Section: Structure Of Fpegmentioning

confidence: 99%

“…Setting the proper mover motion improves the thermal efficiency of the engine and the power generation efficiency of the linear generator. Delaying piston operation immediately after combustion can improve the engine thermal efficiency of the engine [25]. Extending the stroke with a single engine type using a spring suppresses the maximum braking force of the linear generator and reduces copper loss [15].…”

Section: Introductionmentioning

confidence: 99%

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Generator Design Considering Mover Action to Improve Energy Conversion Efficiency in a Free-Piston Engine Generator

et al. 2021

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In a free-piston engine generator (FPEG), the power of the engine can be directly regenerated by linear generators without a crank. The mover motion of this system is interrelated with engine and power generation efficiencies due to the direct connection between the mover of the generator and the piston of the engine. The generator should be designed to improve the overall energy conversion efficiency. The dimensions and mass of the mover limit its operating stroke and drive frequency. Herein, we propose a method for designing linear generators and constructing FPEG systems, considering the mover operation to improve engine efficiency. We evaluated the effect of mover operation on the engine and generation efficiencies using thermal and electromagnetic field analysis software. The proposed design method improves the overall energy conversion efficiency compared with a generator that considers only the maximization of generation efficiency. Setting the mover operation for higher engine efficiency and designing a linear generator to realize the operation can effectively improve the energy conversion efficiency of FPEGs.

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Section: Structure Of Fpegmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Generator Design Considering Mover Action to Improve Energy Conversion Efficiency in a Free-Piston Engine Generator

et al. 2021

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“…A neural network algorithm has been proposed for environmental factors, such as temperature and pressure, to realize the variable compression ratio combustion [17]. Delaying the piston movement by maximizing the braking force near the top-dead-center (TDC) leads to the improvement in the constant volume degree of the engine [18].…”

Section: Introductionmentioning

confidence: 99%

Operation Range of Intermittent Velocity Control for Improving Top-Dead-Center Accuracy in Dual-Sided Free-Piston Engine Linear Generator

Sato,

Irie,

Mizuno

et al. 2023

IEEE Access

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A free-piston engine linear generator (FPEG) is constructed by combining a reciprocating internal combustion engine and a linear generator. FPEG is required to improve both the accuracy of the top-dead-center (TDC) positioning considering frequent combustion fluctuations and the reduction of power consumption. This paper confirms the influence of intermittent velocity control on power running suppression and TDC position deviation in a dual-cylinder FPEG. Intermittent velocity control is a simple method, which consists of repeatedly turning the speed control on and off. The experimental results of the glow engine indicate that this control suppresses power consumption and enables continuous combustion. The setting range for intermittent speed control, which continues operation only through regenerative operation, must be determined by considering the gain value. In addition, this paper explains the effects of the control range of intermittent velocity control on power generation efficiency, piston motion frequency, and TDC position deviation in the dual-cylinder FPEG. Increasing the range ratio of intermittent speed control improves power generation efficiency, but it also increases the standard deviation of TDC position.INDEX TERMS Free-piston engine, linear generator, generation control, speed control, and top-deadcenter

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“…The thrust is adjusted and the piston (i.e., the mover) without the crank can be operated arbitrarily by using the inverter current control of the linear generator [19]. Up to now, improvements in thermal and power generation efficiencies have been reported by taking advantage of arbitrary operability of piston [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…The FPEG mainly required power generation; however, the linear generator is motored to drive the piston to start the engine from the time it is stopped until the engine is ignited [21]. Series hybrid vehicles do not keep the engine running all the time; instead, they turn on and off depending on the battery charge state.…”

Section: Introductionmentioning

confidence: 99%

Resonant Combustion Start Considering Potential Energy of Free-Piston Engine Generator

et al. 2020

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Free-piston engine generators without a crank mechanism are expected to be used in series hybrid vehicles because of their lower losses. The series hybrid system requires a low starting thrust because the engine frequently starts depending on the battery state. This study clarifies the effectiveness of the constant thrust resonance starting method that utilizes the compression pressure of the engine and the spring thrust. The piston must pass the combustion starting point with a predetermined speed to start combustion. Herein, we present a thrust setting method that uses the energy state diagram to optimize the velocity at the combustion start point. A simulation is performed assuming output when mounted on a vehicle. Consequently, the simulation results show that the maximum thrust can be reduced by more than 90% compared to that without resonance. Moreover, the speed at the combustion start point is in agreement with the value obtained using an energy state diagram. An impulse-like combustion pressure is generated in 180 ms, and combustion can be started using resonance, as shown in an experiment using a small-output engine and linear motor. The effectiveness of the constant thrust resonance starting method was confirmed.

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Improving the constant‐volume degree of combustion considering generatable range at low speed in a free‐piston engine linear generator system

Cited by 5 publications

References 11 publications

Generator Design Considering Mover Action to Improve Energy Conversion Efficiency in a Free-Piston Engine Generator

Generator Design Considering Mover Action to Improve Energy Conversion Efficiency in a Free-Piston Engine Generator

Operation Range of Intermittent Velocity Control for Improving Top-Dead-Center Accuracy in Dual-Sided Free-Piston Engine Linear Generator

Resonant Combustion Start Considering Potential Energy of Free-Piston Engine Generator

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