Libralato Ltd benefits from engine design review

Project results in identification of areas for improvement in the design and assembly of the engine, resulting in reduced risk and cost.

PROJECT

Design review of the Libralato Mk3 engine design.

BACKGROUND

Libralato Ltd is an R&D company developing the Libralato rotary engine – an eco-engine for the 21st century. It is the world’s first “one stroke” rotary Atkinson cycle engine. All of the engine phases are completed in parallel in each rotation. It has a completely new thermodynamic cycle which is predicted to achieve c.40% efficiency using gasoline because of its asymmetrical expansion and compression volumes and because it does not need to convert the reciprocating motion of pistons into the rotational motion of the output shaft. It has no need for conventional cylinders, pistons, con-rods, crankshafts, valve trains and camshafts. It is tuned for lean burn combustion, with high and constant levels of torque, very low vibration and very low exhaust temperature and noise.

PROJECT AIM

Review all aspects of the Mk3 fundamental design. In particular, to review design arrangements for:

a). Material Selection, Surface Treatments

b). Sealing, Lubrication

NEED FOR IMPROVEMENT

A brief initial analysis of the engine design identified areas of concern with the design, tolerancing and likely manufacturing cost of some components, the material choices, lubrication methods and the assembly of the components.

APPROACH

EDL’s chief designer attended a round table meeting with the existing partners in order to agree the specific areas to be targeted for improvement.

Once identified, EDL staff reviewed the design of the components based on their experience of designing and manufacturing high speed motor racing engines. As EDL is a private business competing against OEM or alternatively subsidised competitors, it is uniquely placed to offer advice on the design and manufacture of high performance engine components in a cost efficient manner.

Dan Aris, MD of Libralato said,

“We are extremely grateful to EDL and the NAA for their support. The Libralato engine has global potential if we can get the devil out of the details!”

OUTCOMES

In performing the design review some significant risks in the engine design have been mitigated and production costs for the 2 cylinder version reduced. Additionally the engine can now be made in a single cylinder form if required, potentially further significantly reducing the cost of prototype part manufacture and testing.

Specific outcomes:

Drive shaft – Replace bespoke multi spline drive with DIN standard drive which has increased surface and cross sectional area but fits within the same space within the rotor.

Lubrication system – redesigned to prevent oil contamination by exhaust gases and to provide adequate flow to the bearings.

Link head sealing – use conventional seals with a controllable gap to prevent link head seizing and carbon contamination.

Main shaft – change to 2 piece design to allow rotors to be assembled to shafts whilst incorporating a conventional power output drive flange. This would also allow the manufacture of a single cylinder version of the engine, thereby reducing the prototype parts cost significantly.

Link to Case Study:- Libralato_EDL_NAA_Case Study