free piston engine

57
FREE PISTON ENGINE Presented by: Shubham Khandelwal Anshul Garg Anshumaan Malethia Abhinshu Gupta

Upload: danielbi

Post on 02-Dec-2014

223 views

Category:

Documents


24 download

DESCRIPTION

A brief overview about free piston engines...

TRANSCRIPT

Presented by: Shubham Khandelwal Anshul Garg Anshumaan Malethia Abhinshu Gupta

The

free-piston engine is a linear, 'crankless' combustion engine, in which the piston motion is not controlled by a crankshaft but is a result of the interaction of forces from the combustion cylinder gases, a rebound device(e.g., a piston in a closed cylinder) and a load device(e.g. a gas compressor or a linear alternator).

The

free-piston diesel engine concept was developed by Pescara, and engines of various size were manufactured between 1930-1960 by GM, Ford, Renault, Junker, Sigma and others.

General motor XP-500

It

is a combination of reciprocating engine and a rotary turbine.

Bounce Chamber

Intake Air valve

Scavenge Air Box

Supercharge pump

Power turbine

Exhaust gas receiver

Specifications 100 kW peak electrical output power Four free piston engine sub-modules 8 cylinders 2.82 litre displacement 30 Hz operation (equivalent to 1800rpm in a two stroke crankshaft engine) 280x280x660 mm dimensions

A cycle starts with the pistonplunger combination in BDC: most to the right. The electronic control opens the frequency control valve. This increases the pressure in the compressor cylinder, moving the pistonplunger to the left. Simultaneously, air is compressed in the combustion cylinder and oil is sucked into the power cylinder. When the piston-plunger arrives in TDC fuel is injected and ignites. The expanding gases will force the piston plunger to move back to BDC. Oil is pumped to the high pressure side. The burned gases are replaced by fresh air due to the loop scavenging process. In the BDC the piston-plunger will wait until the electronic control gives a new starting signal to the frequency control valve.

Efficiency-During tests, the free piston engine reached an indicated efficiency of more than 50%.

Emissions-It was proven that the combination of a high efficiency combined with low soot and low NOx emissions is possible.

Power density-The Chiron has an net effective power of approximately 17kW.Compared with a conventional diesel engine and pump combination, the number of parts of the Chiron is reduced to approximately 40%.

Infinia is a well renowned company that utilizes free piston technology in three types of machines. Generators Cryocoolers Infinias unique stirling design

1-2: Adiabatic compression in compressor cylinder 2-a: Adiabatic compression a-b: Engine combustion b-3: Adiabatic expansion or power stroke in diesel cylinder 3-4: Mixing of m2 kg engine exhaust and m2 kg bypass air 4-5: Adiabatic expansion in turbine

A simple design with high controllability is the main strength of the single piston design compared to the other free-piston engine configurations. The rebound device gives the opportunity to accurately control the amount of energy put into the compression process and thereby regulating the compression ratio and stroke length.

LP

HP

Dual piston engine configuration eliminates the need for a rebound device, as the (at any time) working piston provides the work to drive the compression process in the other cylinder. It has a simple and more compact design with higher power to weight ratio. The control of piston motion, in particular stroke length and compression ratio, has proved difficult.

LP

HP

It was exclusively used in the early free-piston engine designs (1930-1960). The perfectly balanced and vibration- free design is the exclusive feature of this design. Due to elimination of cylinder head, heat transfer losses are also reduced allowing uniflow scavenging giving better efficiency. The piston synchronization mechanism and dual set of main components makes it a bulky and complicated design.

Bounce chamber

Combustion chamber

Piston synchronization

Inward

compression type Outward compression type The basic difference between them is that inward types compress air during inward motion of the piston while the outward types compress air during the outward motion of the piston. Furthermore, inward type is simpler, has less number of working parts and possess better accessibility for maintenance than outward type.

Two-

stroke, since power stroke required on every cycle. performance gap is declining between 2-stroke and 4-stroke engines due to recent increase of interest in 2stroke engine.

Though

Absence of crank mechanism and flywheel leads to :

No motion control and no energy storage. May lead to less or more compression ratios and less time for scavenging.

Measures to previous problems :

Motion is controlled by sum of forces acting on piston at any time.