Feasibility of Multiple Piston Motion Control Approaches in a Free Piston Engine Generator

2019 ◽  
Author(s):  
Mehar Bade ◽  
Nigel Clark ◽  
Parviz Famouri ◽  
PriyaankaDevi Guggilapu
Keyword(s):  
Motion Control ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Free Piston Engine

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

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.

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.

In-cylinder heat transfer and gas motion of a free-piston diesel engine generator

2017 ◽  
Vol 231 (8) ◽  
pp. 739-752 ◽  
Author(s):  
Chenheng Yuan ◽  
Jing Xu ◽  
Huihua Feng
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Attractive Alternative ◽  
Piston Engine ◽  
Piston Motion ◽  
Compression Process ◽  
Free Piston ◽  
Reciprocating Engine ◽  
Free Piston Engine ◽  
Significant Difference

The free-piston engine generator is an attractive alternative to the conventional reciprocating engine due to the feature that it moves without crankshaft system. This paper presented a simulation for the investigation on the characteristic of in-cylinder gas motion and heat transfer in a compression ignited free-piston engine generator. An operation experiment was performed to obtain the precise piston motion for the modeling of heat transfer and gas flow. The development of the multi-dimensional model was described, and simulation results were presented and showed good similarity with the experimental data. Then, the heat transfer and gas motion in the free-piston engine generator were discussed, on which the influences of piston motion were also investigated compared with a corresponding conventional reciprocating engine. The results indicated that compared with the conventional reciprocating engine, a higher level of squish and reverse squish effect was found for the free-piston engine generator due to its faster motion around top dead center, while its slower piston motion led to weaker gas turbulence in the compression process. Moreover, the free-piston engine generator and conventional reciprocating engine did not show a significant difference in heat transfer during the compression process, however, an obvious advantage of heat transfer was indicated for the free-piston engine generator in combustion and expansion processes due to its lower combustion temperature and the reduced time that is available for heat transfer caused by its faster expansion. The mechanism for such differences is that the free-piston engine generator moves with uneven equivalent speed.

scholarly journals A Reciprocating Motion Control Strategy of Single-Cylinder Free-Piston Engine Generator

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 245 ◽  
Author(s):  
Hao Yan ◽  
Zhaoping Xu ◽  
Jinkang Lu ◽  
Dong Liu ◽  
Xiaohui Jiang
Keyword(s):  
Motion Control ◽  
Control Strategy ◽  
Electrical Power ◽  
Reciprocating Motion ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Finite State ◽  
Turning Center ◽  
Combined Simulation

Free-piston engine generator is a novel electrical power generating system developed for electric vehicles, and it is labeled as a more efficient power system than conventional engines. This paper proposes a reciprocating motion control strategy of free piston to enable the stable running of the system. The control problem was decomposed to the stroke control, the top turning center (TTC) control, and the bottom turning center (BTC) control for reducing unnecessary energy consumption during the control. An iterative learning controller (ILC) was designed for the TTC control, the BTC control was based on the combustion states estimation, and the stroke control was based on finite-state machine (FSM). The turning centers of the previous stroke and the maximum cylinder pressure of the current stroke were taken for feedback. A combined simulation model including the combustion cycle fluctuation was presented and validated by the prototype, and the performance of the control strategy was analyzed. The results showed that the system obtained the stable running and the reciprocating motion of the free piston was well controlled.

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