This document provides an overview of a review on free piston linear engines (FPLEs) and their control systems. It discusses the basics of FPLEs, including their operating principle and various piston configurations like single piston, dual piston, and opposed piston. It also describes experimental setups used to test FPLEs. Additionally, it covers piston dynamics and control topics like timing control, starting/restarting control, and misfire control. Applications of FPLEs discussed include improvements to efficiency, emissions reductions, and use in hybrid electric vehicles. The conclusion summarizes that two-stroke FPLEs are most commonly investigated due to advantages in structure and control.

1. A REVIEW ON FREE PISTON LINEAR
ENGINE AND ITS CONTROL SYSTEM
BY:
SHAFEEQUR RAHMAN S.I
SURYA KANDHASWAMYT
Dr P. GOPAL
Department of Automobile Engineering
ANNA UNIVERSITY
BHARADHIDASAN INSTITUTE OF TECHNOLOGY(BIT) CAMPUS
TIRUCHIRAPPALLI-620024

2. CONTENTS
• Introduction
• Free-piston engine basics
• Operating principle
• Piston configuration
• Single piston
• Dual piston
• Opposed piston
• Experimental setups
• Piston dynamics and control
• Starting
• Misfiring
• Applications of FPLE
• Conclusion
• References

3. Introduction
• FPLE is nothing but an engine works without crankshaft
• Instead of crankshaft , here an turbine and linear alternator is used to
convert the rotary motion into reciprocatory motion
• This crank less engine reduce the losses due the crankshaft

4. Operating principle

5. 1. It includes a single-piston, cylinder, and rebound
device
2.The single-piston FPLE is mechanically simple with
high controllability when compared to other FPLEs
1. It consists of two combustion chamber and a dual-piston
2.This engine eliminates the need for a rebound device, as the working piston
provides the work to drive the compression process
3. In the other cylinder, which allows a simple and more compact device with
higher power to weight ratio
1. It consists of two single piston units with a single combustion
Chamber
2. Its pistons are synchronized by mechanical linkages to eliminate
mechanical vibration, which is not found on any other linear
engines
3. A shared combustion chamber also reduces heat losses.
PISTON CONFIGURATION
Single piston.
Dual piston.
Opposed
piston.

6. Experimental systems
• Single piston engine with linear alternator
• Opposed piston engine setup
• Dual piston engine setup

7. PISTON DYNAMICS AND
CONTROL
• Timing Control
• Starting/ Restarting Control
• Misfire Control
• PistonTDC Control

8. Applications of FPLE
• FPLEs decrease heat transfer loss in the cylinder by increasing piston
acceleration, compared with conventional engines
• The implementation of springs in FPLEs shows benefits for increasing piston
velocity and engine performance.
• In addition to benefit of piston dynamics, published results show that the
thermal efficiency of FPLEs is higher than that of conventional engines.

9. Applications of FPLE (cont…)
• the simulation results of FPLEs show benefits for reducing temperature-dependent emissions (NO)
because the in cylinder gas temperature of FPLEs is generally lower than that of conventional engines.
• The variable compression ratio in FPLEs is a great benefit for combustion.
• By changing the compression ratio, FPLEs can optimize the combustion process and operate with
various kinds of fuels and HCCI combustion.
• A free-piston engine can not only be operated as a conventional internal combustion engine. It can also be
integrated with a linear alternator to generate electric power
• The electric power can be optimized by adjusting parameters such as piston assembly mass, ignition
timing, equivalence ratio, electrical resistance, and air gap.

10. Conclusion
• In this paper, we have reviewed on FPLEs with varied designs and operating features.
• For piston stroke type, two-stroke FPLEs are most-commonly investigated and developed
because of their advantages in structure and control.
• Much research has shown that a linear alternator with a high efficiency
• power source is an excellent power-unit candidate for HEVs.With the potential offered by high-
efficiency linear alternators in FPLEs, we expect integrated systems to be further developed and
applied in the near future.

11. References
• Mikalsen R, Roskilly AP. A review of free-piston engine history and application. ApplTherm Eng 2007; 27:2339–52.
• Mikalsen R, Roskilly AP.The control of a free-piston engine generator. Part 1: fundamental analysis. Appl Energy
2010; 87:1273–80.
• Goertz M, Peng L. Free piston engine its application and optimization. SAE paper 2000-01-0996; 2000.
• Kosaka H, AkitaT, Moriya K, Goto S, HottaY, UmenoT, et al. Development of free piston engine linear generator
system part 1 – investigation of fundamental characteristics. SAE paper 2014-01-1203; 2014.
• Blarigan PV. Free-piston engine. US patent no. 6199519 B1; March 13, 2001.
• Mikalsen R, Roskilly AP.The fuel efficiency and exhaust gas emissions of a low heat rejection free-piston diesel
engine. Proc IMech Part A: J Power Energy 2009; 223:379–84.
• Blarigan PV. Advanced internal combustion electrical generator. In: Proceedings of the 2001 DOE hydrogen
program review. p. 1–16.
• Wakabayashi R,Takiguchi M, Shimada T, MizunoY,Yamauchi T.The effects of crank ratio and crankshaft offset on
piston friction losses. SAE paper 2003-010983;2003.
• Farmer HO. Free piston compressor engines. Proc Inst Mech Eng 1947; 156:253–71.
• Ostenberg P. Electric generator. US patent 2362151 A; 1944.

12. ThankYou