Introduction
The K6 ‘York’ rotary engine project has been incubated and supported by Railfast Intermodal Limited since January 2016, with the core IP belonging to Jordans Consultancy as innovators. The initial design was originally conceived for steam locomotives, but was quickly seen as being applicable to Internal Combustion (IC) engines also.
Background
Today, when we think of an IC engine, we invariably think of one or more pistons driving a crankshaft. This is because no-one to date has come up with an alternative which delivers the level of power, reliability and range needed for applications such as motor vehicles (road and rail), small boats and aircraft, standby power and pumps at a cost which people are willing to pay.
When people talk about the IC engine having ‘reached its limits of development’ it is this conventional piston-and-crank model which they are referring to, which has indeed reached its limits. In order to eke out a few more percentage points of performance, manufacturers have turned to special coatings, turbochargers and complex engine management systems, as well as AdBlue in diesel engines to try and deal with emissions which turbochargers etc. have helped to create.
Far From Ideal
Anyone who works with conventional IC engines, and particularly the higher efficiency Compression Ignition (CI) type, will tell you that they are far from being an ‘ideal heat engine’:
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Ignition is at the point of minimum leverage on the crankshaft, leading to a significant proportion of the energy from combustion being wasted as heat.
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Significant energy is wasted through having to reverse the direction of the pistons at very high G-forces.
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Fuels have to be precisely graded, due to the time delay between injection and ignition.
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Matching power demand with engine speed often requires the use of a complex transmission.
For those having an understanding of the Carnot cycle, a quick calculation shows the theoretical potential for improvement far beyond the present 35% maximum level of efficiency for a typical automotive engine.
None of the 'add-on' technologies, such as turbochargers or Engine Management Systems, address the above shortcomings.
Rotary Engines to Date
Gnome Rotary Engine
The Gnome rotary aero engine of the early 20th Century was remarkable for having piston reciprocation based upon different centres of rotation; the engine block rotated about one centre and the piston conrods rotated about another. Inadequate aspiration of what became a large and complex engine led to further development being abandoned.
Wankel
The Wankel engine today is what most people think of as the typical rotary engine. This type of engine has certain advantages in terms of quietness of operation, smoothness, a linear power curve and a good power-to-weight ratio. Unfortunately, these advantages have historically been offset by poor fuel consumption, high emissions, and excessive rotor wear (the latter necessitating frequent engine overhauls). Whilst attempts to improve the performance and reliability have continued over the years, fundamental issues remain.
The Wankel is noteworthy for having a fixed stator with spark plugs, inlet and outlet ports, which the rotor is able to sweep past. Hence the different elements of the combustion cycle happen at fixed points through 360 degrees.
A trawl of a patents database shows that the vast majority of filings for rotary-type engines since 1960 appear to be variations on Wankel’s original ideas.
As spark ignition engines, both these rotary engine types fail to reach acceptable modern day efficiency levels.
K6 Mechanics
Mechanically at least, the K6 rotary engine represents a return to the more familiar piston-in-cylinder method of extracting work from an expanding gas. This has served humankind well in its various forms for nearly three centuries. Utilising the Gnome principle, it has them contained within a cylinder block which forms a rotor within a fixed stator. Hence, just like the Wankel, the different stages of the combustion cycle happen at fixed degrees of rotation. However, this is the only similarity between the Wankel and the K6.
The following video shows how the required piston movement is achieved within the rotor.
The ability of the K6 to have a conrod:stroke ratio of close to the theoretical minimum of 0.5 (0.55 in practice) generates a relative movement of the piston-within-cylinder which is decidedly non-sinusoidal, creating a whole new set of engine performance characteristics.
Of note is a fan as an integral part of the rotor, which assists with the charge air supply.
In summary, the K6 promises:
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A radically different fuel/air mixing process and ignition/combustion.
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A dramatically reduced engine phase angle occupied by the hot cycle.
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The existence of high torque - the ability to do work – immediately after TC.
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Default inlet and exhaust ports of 100% of the cylinder section.
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A separate piston-ported scavenge port with independent timing.
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Single inlet and exhaust fluid flows – no manifolds.
Expert Scrutiny
Having scrutinised the K6 internally for some 3-4 months and finding no obvious flaws, a decision was taken to approach University of Birmingham. Railfast Intermodal used existing contacts at the Birmingham Centre for Railway Research & Education (BCRRE), namely Prof. Felix Schmid, Professor of Railway Systems Engineering. Felix, in turn, put us in contact with Prof. Miroslaw Wyszynski, Professor of Thermodynamics in the Department of Mechanical Engineering.
Students have successfully undertaken K6-related projects as part of their degree course, looking at both steam and IC variants.
A paper entitled ‘COMPUTATIONAL MODELLING OF THE FUEL INJECTION AND COMBUSTION IN A DIESEL K6 ROTARY ENGINE’ was presented by Prof. Wyszynski at the 44th International Scientific Congress on Powertrain and Transport Means EUROPEAN KONES, Czestochowa & Wisla (Poland), 24th – 27th September 2018, where it was well received.
Our Consulting Engineeer, Richard Coleby, has kindly allowed us to draw upon his extensive CAD design knowledge and experience to create preliminary drawings which have now been turned into a motor-driven 3-D printed model.
The vital work undertaken, both by University of Birmingham and Richard Coleby, has laid the foundation for a programme of wider scrutiny by a much wider technical audience, beginning with a stand at the IMechE Midland Engineering Dinner on Friday 18th October at the National Motorcycle Museum, Birmingham, England.
Theoretical Performance Characteristics
Theoretical calculations regarding theoretical performance, power-to-weight etc., are such that we hesitate to post them publicly. Suffice to say that a thermal efficiency in excess of 60% is seen as being theoretically possible (compared to a maximum thermal efficiency of a conventional CI automotive engine of around 35%).
Cost
Whilst exact numbers cannot be determined as yet, the inherent simplicity of the K6, the lack of high-stressing G-forces and the ability to dispense with many components essential to the conventional CI engine mean that the cost of a K6 is likely to prove significantly less than for its conventional equivalent.
Patent Protection
UK Patent Application (NP1) Number 1816159.6 was filed in April 2016 in relation to core aspects of the design. Given that there have been (as yet) no serious challenges with respect to prior art, we expect the application to be granted.
Applications
Applications are numerous and varied; essentially anywhere where a conventional IC engine is currently employed, with the potential to replace other types of engine such as turbines in some cases.
Of particular interest to the K6 Development Team is the development of compact, quiet, affordable home CHP units.
Prospectus
The latest prospectus detailing the requirements for Phase II (prototyping) may be requested by emailing This email address is being protected from spambots. You need JavaScript enabled to view it.. The prospectus is currently under review, but should be ready for issue by Tuesday 10th March 2020.
People
Please feel free to contact This email address is being protected from spambots. You need JavaScript enabled to view it. (Project Manager) or This email address is being protected from spambots. You need JavaScript enabled to view it. (Technical Lead).