Study on the Starting Process Driven by Accumulator of a Hydraulic Free Piston Engine

Xia, Bi Zhong; Su, Gang; Xie, Haibo; Yang, Hua

doi:10.4028/www.scientific.net/amm.121-126.3092

Cited by 3 publications

(4 citation statements)

References 4 publications

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“…Actually, the HFPE descends from the free-piston engine and carries it forward. It is synthesized by an internal combustion engine, hydraulic technology and electronic control technology [6]. HFPE development roughly experienced the following stages: (1) Initial stage (1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990) Figure 2 shows a hydraulic free-piston which uses a two-stroke reflux scavenging scheme: its load is hydraulic oil with a certain pressure; a hydraulic accumulator is applied as the energy storage component [7].…”

Section: The History Of Hfpesmentioning

confidence: 99%

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Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Zhang

Zhao

et al. 2021

Energies

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The hydraulic free-piston engine (HFPE) is a kind of hybrid-powered machine which combines the reciprocating piston-type internal combustion engine and the plunger pump as a whole. In recent years, the HFPE has been investigated by a number of research groups worldwide due to its potential advantages of high efficiency, energy savings, reduced emissions and multi-fuel operation. Therefore, our study aimed to assess the operating characteristics, core questions and research progress of HFPEs via a systematic review and meta-analysis. We included operational control, starting characteristics, misfire characteristics, in-cylinder working processes and operating stability. We conducted the literature search using electronic databases. The research on HFPEs has mainly concentrated on four kinds of free-piston engine, according to piston arrangement form: single piston, dual pistons, opposed pistons and four-cylinder complex configuration. HFPE research in China is mainly conducted in Zhejiang University, Tianjin University, Jilin University and the Beijing Institute of Technology. In addition, in China, research has mainly focused on the in-cylinder combustion process while a piston is free by considering in-cylinder combustion machinery and piston dynamics. Regarding future research, it is very important that we solve the instabilities brought about by chance fluctuations in the combustion process, which will involve the hydraulic system’s efficiency, the cyclical variation, the method of predicting instability and the recovery after instability.

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Section: The History Of Hfpesmentioning

confidence: 99%

“…Energies 2021, 14, x FOR PEER REVIEW 3 of 23 (a) The combination of engine and hydraulic pump (b) The hydraulic free-piston engine Figure 1. The different structures of a conventional engine and an HFPE [6].…”

Section: The History Of Hfpesmentioning

confidence: 99%

Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Zhang

Zhao

et al. 2021

Energies

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“…Xia and Zhou of Zhejiang University studied DHFPE and focused on the energy distribution, control of the compression ratio, and the vibration of the piston. The results showed that the vibration of the piston was a self-excited vibration and the engine was a large scope stability system [9][10][11]. Zhao and Yuan of Beijing Institute of Technology also developed an SHFPE and utilized the uniflow scavenge to improve the scavenge ratio.…”

Section: Introductionmentioning

confidence: 99%

Influence of Pressure Build-Up Time of Compression Chamber on Improving the Operation Frequency of a Single-Piston Hydraulic Free-Piston Engine

Xie

Ren

Yang

et al. 2013

Advances in Mechanical Engineering

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A single-piston hydraulic free-piston engine with a two-cylinder four-stroke diesel engine as its driver is introduced. It takes the free-piston assembly a certain time to move after the pressure in the compression chamber starts to increase. The time difference between the pressure increasing and the piston starting to move is defined as the pressure build-up time. The characteristics of the pressure build-up time and its influence on the performance of the free-piston engine are introduced and analyzed. Based on the basic law of dynamics of the free-piston assembly, the parameters which influence the pressure build-up time are analyzed. And then improvement and optimization are proposed to shorten the pressure build-up time.

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“…The SHFPE belongs to single-cylinder diesel engine and has an imbalance structure, so the alternant forces of the compression accumulator and the released heat of the injected fuel acting on the FPA lead the engine body to vibrate. Generally, the engine body is mounted to the base by the bolts with some vibration absorptions [6,7] . The body vibration can also be eliminated through putting several engine units symmetrically to get a balance structure [7,8] .…”

Section: Introductionmentioning

confidence: 99%

Dynamic Analysis of the Single Piston Hydraulic Free Piston Engine

Ren

Xie

Yang

2011

AMM

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The connection of the engine body and the base was simplified as a spring and a damper to analyze the body vibration of the single piston hydraulic free piston engine. It was demonstrated that the increasing of the connection spring rate can reduce the amplitude of the body vibration. But the reduced vibration amplitude was trivial after the spring rate was increased above 300KN/m. The damp ratio of the connection had little influence on the body vibration. The introduction of a pump chamber into the structure in the compression stroke can shorten the rebounding displacement of the free piston assembly (FPA) while it was settled at the right dead center working in pulse pause modulation (PPM) mode. Furthermore it can keep the FPA have an enough stroke to achieve a predetermined compression ratio and reduce the fluctuation of the pump flow. The compression ratio can be improved through increasing the pressure of the compression accumulator and decreasing the pressure of the high pressure accumulator. Also the compression ratio and the operation frequency of the engine can be improved by shortening the switch time of the control valve and prolonging the open time.

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Study on the Starting Process Driven by Accumulator of a Hydraulic Free Piston Engine

Cited by 3 publications

References 4 publications

Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Influence of Pressure Build-Up Time of Compression Chamber on Improving the Operation Frequency of a Single-Piston Hydraulic Free-Piston Engine

Dynamic Analysis of the Single Piston Hydraulic Free Piston Engine

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