Transient Control of a Hydraulic Free Piston Engine

2013 ◽  
Author(s):  
Ke Li ◽  
Chen Zhang ◽  
Zongxuan Sun
Keyword(s):  
High Efficiency ◽  
Combustion Engine ◽  
Tracking Error ◽  
Control Signal ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Engine Operation ◽  
Free Piston Engine ◽  
Transient Period

The free piston engine (FPE) is a type of internal combustion engine (ICE) with no crankshaft, so that its piston motion is no longer constrained by mechanical linkages. The FPE has a high potential in terms of energy saving given its simple structure, high modularity and high efficiency. One of the technical barriers that prevents the wide spread of the FPE technology, is the lack of precise piston motion control. Previously, a robust repetitive controller is designed and implemented to form a virtual crankshaft that would provide a precise and stable engine operation. The experimental data of engine motoring tests with virtual crankshaft demonstrates the effectiveness of the controller. However, the presence of a transient period after a single combustion event prevents the engine from continuous firing. This paper presents a modified control scheme, which utilizes a reference and control signal shifting technique to modify the tracking error and the control signal to reduce the transient period.

scholarly journals Hydraulic Free Piston Engine Enabled by Active Motion Control

2013 ◽  
Vol 135 (06) ◽  
pp. S7-S9 ◽  
Author(s):  
Ke Li ◽  
Zongxuan Sun
Keyword(s):  
Motion Control ◽  
High Efficiency ◽  
Motion Controller ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Engine Operation ◽  
Active Motion ◽  
Functional Aspects ◽  
Free Piston Engine

This article explores various functional aspects of hydraulic free piston engine (FPE) enabled by action motion control. Given the potential for high efficiency and flexibility, the FPE is well suited for mobile applications such as on-road vehicles and off-road heavy machinery. The advantage of the active motion controller lies in its ability to precisely track and shape the piston trajectory. FPE has a great potential for energy saving and emission control, but its reliable operation is limited by the complex dynamic coupling among the engine subsystems and the lack of the crankshaft. This inherent technical barrier for FPE could be overcome by active control with today’s sensing, actuation and computing technologies. A prototype hydraulic FPE is used to demonstrate the capabilities of active piston motion control. Experimental results demonstrate the feasibility and promise of the technology. Engine power control will be combined with piston motion control in the future to achieve a wider range of engine operation and higher engine efficiency.

scholarly journals Wall Heat Transfer Analysis of Internal Combustion Engine with Free Piston Linear Motion

2018 ◽  
Vol 7 (3.17) ◽  
pp. 141
Author(s):  
Mior A. Said ◽  
L K. Mun ◽  
A R. A. Aziz ◽  
. .
Keyword(s):  
Heat Transfer ◽  
Transfer Rate ◽  
Combustion Engine ◽  
Linear Motion ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Free Piston Engine ◽  
Set Up ◽  
Motion Profile

The manuscript should contain an abstract. The abstract should be self-contained and citation-free and should not exceed 200 words. The abstract should state the purpose, approach, results and conclusions of the work.  The author should assume that the reader has some knowledge of the subject but has not read the paper. Thus, the abstract should be intelligible and complete in it-self (no numerical references); it should not cite figures, tables, or sections of the paper. The abstract should be written using third person instead of first person. Intensive researches are being carried out on the main power generator for free piston linear generator(FPLG) by both the academic and industrial research group due to its potential as a high fuel efficiency and low emission engine. The linear generator, which is a coil and a translator positioned to move linearly back and forth relative to each other. The study investigates the heat transfer data of internal combustion engine with free piston linear motion profile and compared with the conventional reciprocating engine for one cycle motion only. Engine simulation software GT-Power is employed which utilize the 1-D thermodynamic modeling. All parameters for both free-piston engine are set-up to be the same except for the piston motion profile and the injection timing. Both conventional and free piston engine models are built, simulation settings are set up, and simulations are launched in GT-ISE.  Once simulation is done, results are viewed in GT-POST, the data collected was analysed and compared to investigate the dictinct effect of piston motion to heat transfer profile and data. The overall trend shows that free piston engine have a lower heat transfer rate throughout majority of the cycle. This finding agrees that due to less time of piston near top dead centre area, heat transfer losses to the wall per cycle are reduced. The heat transfer profile of the free piston also shown distinct feature compared to conventional with rapid increase and decrease of heat transfer rate, followed by a secondary peak of gradual decline of the profile.  

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

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3530
Author(s):  
Fukang Ma ◽  
Shuanlu Zhang ◽  
Zhenfeng Zhao ◽  
Yifang Wang
Keyword(s):  
Systematic Review ◽  
High Efficiency ◽  
Meta Analysis ◽  
Combustion Process ◽  
Research Progress ◽  
Future Research ◽  
Operating Characteristics ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

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.

scholarly journals Research of a Hybrid Diesel Locomotive Power Plant Based on a Free-Piston Engine

2020 ◽  
Vol 22 (3) ◽  
pp. 103-109
Author(s):  
Serhiy Buriakovskyi ◽  
Borys Liubarskyi ◽  
Artem Maslii ◽  
Danylo Pomazan ◽  
Tatyana Tavrina
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Diesel Generator ◽  
Piston Engine ◽  
Diesel Locomotive ◽  
Free Piston ◽  
Electric Transmission ◽  
Free Piston Engine ◽  
Hybrid Transmission

This article describes one of the possible ways for improving the energy efficiency of shunting diesel locomotives. It means a replacing a traditional traction electric transmission with a diesel generator set with a hybrid transmission with a free-piston internal combustion engine and a linear generator. The absence of a crankshaft in an internal combustion engine makes it possible to reduce thermal and mechanical losses, which, in turn, leads to an increase in the efficiency of traction electric transmission of the diesel locomotive.

scholarly journals Design considerations of a linear generator for a range extender application

2015 ◽  
Vol 64 (4) ◽  
pp. 581-592
Author(s):  
Un-Jae Seo ◽  
Björn Riemer ◽  
Rüdiger Appunn ◽  
Kay Hameyer
Keyword(s):  
Electric Vehicle ◽  
High Efficiency ◽  
Piston Engine ◽  
Free Piston ◽  
Full Load ◽  
Linear Generator ◽  
Design Considerations ◽  
Range Extender ◽  
Free Piston Engine ◽  
Linear Generators

Abstract The free piston linear generator is a new range extender concept for the application in a full electric vehicle. The free piston engine driven linear generators can achieve high efficiency at part and full load which is suitable for the range extender application. This paper presents requirements for designing a linear generator deduced from a basic analysis of a free piston linear generator.

New Free-Piston Topping Cycle for Gas-Turbine Power Plants

2003 ◽  
Author(s):  
William L. Kopko ◽  
John S. Hoffman
Keyword(s):  
High Performance ◽  
Power Plants ◽  
Waste Heat ◽  
Combustion Engine ◽  
Complete Recovery ◽  
Combined Cycle ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Topping Cycle

A proposed topping cycle inserts a free-piston internal-combustion engine between the compressor and the combustor of a combustion turbine. The topping cycle diverts air from the compressor to supercharge the free-piston engine. Because the free-piston engine uses gas bearings to support the piston and is built of high-temperature materials, the engine can increase the pressure and temperature of the gas, exhausting it to a small expander that produces power. The exhaust from the topping-cycle expander is at a pressure that can be re-introduced to the main turbine, allowing almost complete recovery of waste heat. A capacity increase exceeding 35% is possible, and overall cycle efficiency can approach 70% when incorporated into a state-of-the-art combined-cycle plant. The cost of per incremental kW of the topping cycle can be dramatically lower than that of the base turbine because of the high power density and simplicity of the engine. Building on decades of progress in combustion turbines systems, the new cycle promises high performance without the engineering risks of manufacturing a completely new cycle.

scholarly journals Piston motion control of a free-piston engine generator: A new approach using cascade control

2016 ◽  
Vol 179 ◽  
pp. 1166-1175 ◽  
Author(s):  
Boru Jia ◽  
Rikard Mikalsen ◽  
Andrew Smallbone ◽  
Zhengxing Zuo ◽  
Huihua Feng ◽  
...  
Keyword(s):  
Motion Control ◽  
Cascade Control ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
New Approach ◽  
Free Piston Engine

A Virtual-Cam Control Methodology for Free-Piston Engines

2011 ◽  
Author(s):  
Chao Yong ◽  
Eric J. Barth
Keyword(s):  
Internal Combustion Engines ◽  
Control Method ◽  
Piston Engine ◽  
Piston Motion ◽  
Stroke Length ◽  
Free Piston ◽  
Physical Context ◽  
Spark Timing ◽  
Free Piston Engine ◽  
Timing Belt

In conventional internal combustion engines, valves are opened and closed using a cam surface. The cam is kinematically related to the piston positions through the crankshaft and timing belt. In contrast, there is no crankshaft or kinematic cam surface in a free-piston engine to physically realize this mechanism. As a consequence, a free-piston engine has variable stroke lengths, which presents a challenge for active piston motion and precise stroke length control. This paper presents a virtual-cam based approach to relate free-piston motion to actuated engine valve control within a clear and familiar intuitive physical context. The primary functionality of the virtual cam control framework is to create a variable index, which is adjustable from cycle to cycle, for the exhaust/injection valves and spark timing similar to the function of physical cams in conventional engines. Since the cam is virtually created, it can be dynamically rebuilt to comply with cycle-to-cycle variations such as amount of the air/fuel supply, engine load and stroke length. This index rebuilding process is based on a cycle-to-cycle adaptive control method that uses the knowledge obtained from previous cycles to adjust the cam parameters. Preliminary experimental results are presented for a novel liquid-piston free-piston engine intended as a compact and efficient energy source for untethered power dense pneumatic systems such as untethered robots.

Development of free piston engine linear generator system and a resonant pendulum type control method

2020 ◽  
pp. 146808742093124
Author(s):  
Hidemasa Kosaka ◽  
Tomoyuki Akita ◽  
Shigeaki Goto ◽  
Yoshihiro Hotta
Keyword(s):  
Control Method ◽  
Experimental Result ◽  
Piston Engine ◽  
Piston Motion ◽  
Generator System ◽  
Free Piston ◽  
Linear Generator ◽  
Reference Profile ◽  
Cycle Simulation ◽  
Free Piston Engine

A free piston engine linear generator, which has the potential of the compact physique, high brake efficiency and high flexibility for fuel, has been developed. The developed free piston engine linear generator consists of a two-stroke combustion unit, an air-bounce chamber and a linear generator. The key technologies to realize the continuous operation are the control method and lubricating and cooling strategies. The proposed structure is featured as a piston shape with two different diameters coaxially, called a “W-shape” piston, which has an empty space inside for the oil cooling path. The performance of the structure is evaluated by a one-dimensional cycle simulation. The result indicates the possible output power of 10 kW and thermal efficiency of 42% using premixed charge compression ignition combustion strategy. The control method is another challenge of the free piston engine linear generator. This work proposes two strategies of the position feedback control method and the resonant pendulum type control method. The first method has the function of the feedback loops for the piston position and velocity so that the piston motion follows the reference profile calculated in advance. The experimental results show the limited range of operation because the fixed profile does not absorb the deviation of the piston motion due to the combustion deviation. The second method is based on the speed control without a fixed reference profile of the piston motion. The experimental result shows the robustness to the change in operating parameters such as ignition position, amount of fuel and desired power output.

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