New engine technology arrives

Slider engine fixed and ready to roll, say developers

By PH Staff / Thursday, 16 June 2005 / Loading comments

Slider engine

Two developers of slider engine technology, brothers Michael and Peter Raffaele, reckon they have solved on of the problems inherent with the design, and are looking for partners and licensees -- and publicity.

The slider engine was unveiled at the recent Engine Expo in Stuttgart to critical acclaim, developed by Slider Engine Technologies (AU). Visitors saw a highly developed Vee-twin featuring this new engine technology.

Engineers at Slider Engine Technologies said they have developed a way to stabilise the pistons and cranking arrangement of the scotch yoke engine. The company also unveiled manufacturing solutions for V, inline, W, boxer and radial engine configurations.

Accoridng to Slider Engine Technologies, the technology has the potential to unify and rationalise the R&D efforts of manufacturers around the globe. For consumers, uptake of the technology by manufacturers will deliver significant advantages including improved fuel economy and a considerable increase in overall refinement.

Advantages are said to include:

Greater responsiveness / acceleration
Higher maximum RPM
Greater power density and range
Increased volumetric / thermal / mechanical efficiency
Reduced cost of vehicle manufacture
Increase in engine durability
Reduced mass
Reduced NOX & Carbon (equilibrium conditions, crevice volumes)
Reduced idle speed (mechanical efficiency)
Reduced valve inertias (sinusoidal piston motion)
Reduced piston inertias (sinusoidal piston motion)
Massively reduced noise, vibration & harshness

History

The Raffaele brothers became interested in the scotch yoke engines from a TV programme featuring the technical and commercial failure of yet another doomed scotch yoke engine development, which had been underway in Australia for several decades. The brothers asked why scotch yoke engine development been narrowly focused on a boxer configuration.

With this question in mind, and realising the scotch yoke principle could have no commercial future without the inclusion of in-line and V format engines, the Raffaeles began a search of the global patent database and technical publications, while designing and manufacturing a scotch yoke powerplant in order to gain further insight into the mechanism's behaviour under load.

In just over three months the brothers had designed and built an engine from scratch, but this first unit failed within hours.

"We have a policy of jumping in at the deep end", said Michael. "It's been our experience that more finesse, which inevitably soaks up time, doesn't necessarily equal relevant information. We knew from the damage to our prototype what was missing, and why. We learnt that the offset scotch yoke cannot tolerate free rotation of its big end mounted drive block because it leads to the impartation of instantaneous accelerations and a very certain catastrophe.'

Following an intensive review of relevant literature, Mercedes-Benz patent filing DE 3624753 (1986), which included the generic device of a piston guide system for controlling free rotation, became of specific interest to the Raffaeles. However, they realised that what was described could not arrest the problem, the guides being positioned at too distant a location to function effectively.

"We feel that Mercedes-Benz, along with so many others, was defeated by an optical illusion", said Peter. "We suspect they believed that the area swept by the big end of the crankshaft during its rotation was automatically a no-go area for a guide system."

To their immense surprise the brothers found that with simple alterations to the scale of certain components, a rail and race guide system could actually fit into this so called 'prohibited' space. The guides are configured to dip in and out the swept volume without contacting the big end.

Christened the slider engine, the new unit features pistons and con-rods that are twice as expensive to manufacture as those of a conventional powerplant. However, Slider Engine Technologies argues this on-cost is simply dwarfed by the technology's benefits: 30 per cent slower idle speed, 15 per cent increase in max rpm, lighter and far less complex geartrains and drivelines, leading to reduced vehicle mass and cost reductions throughout the entire vehicle.

For European manufacturers with significant investment in technology centred on NVH issues linked to the conventional engine, the Slider Engine could seem to be detrimental to all that they have developed with its inherently superior NVH solution. The Slider Engine team believes this initial reaction is understandable but unlikely to prevail given the size and make up of the global automotive industry.

The slider engine is compatible with all known development trends and fuel types. SLT said its ultra low NVH and increased speed range make it a good platform for development of tomorrows HCCI, VCR and common-rail diesel engines.

With 25-30 years of manufacture still to go before the piston engine is superseded by fuel cells and other more exotic technologies, the only certainty is that development of the combustion engine is not finished.

Since the engine's unveiling at the start of June, SLT said manufacturers have been requesting demonstrations of the unit's capabilities and potential.