Nutating_disc_engine

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Nutating disc engine

A nutating disc engine is a recently patented internal combustion engine comprising fundamentally only one moving part and a direct drive onto the crankshaft. It differs from earlier internal combustion engines in a number of ways and utilizes a type of motion known as nutation.

Operation

In its basic configuration the core of the engine is a nutating non-rotating disc, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disc "nutates," (performs a wobbling motion without rotating around its axis). The motion of the disc circumference prescribes a portion of a sphere. A portion of the area of the disc is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disc. The external combustion chamber enables the engine to use diesel fuel in small engine sizes, giving it unique capabilities for unmanned aerial vehicle propulsion and other applications. One significant benefit of the nutating engine is the overlap of the power strokes.

Power is transmitted directly to the output shaft, (the crankshaft), completely eliminating the need for complicated linkages essential in a conventional piston engine (to change the piston's linear motion to rotating output motion). Since the disc does not rotate, the seal velocities are lower than in an equivalent IC piston engine. However the total seal length is rather long, which may negate this advantage.

The disc wobbles inside a housing and, in its simplest version, half of the single disc (one lobe) performs the intake/compression function, while the other lobe performs the power/exhaust function. Note that the disc lobes can be configured to have equal compression and expansion volumes, or to have the compression volume greater than or less than the expansion volume. This means that the engine can be self supercharged (see supercharger), or operate as a Miller cycle / Atkinson cycle.

Patents and Production History

U.S. patent number 5,251,594 was granted to Leonard Meyer of Illinois in 1993 for a "nutating internal combustion disc engine". The Meyer Nutating Engine is a new type of internal combustion engine with higher power density than conventional reciprocating piston engines and which can operate on a variety of fuels, including gasoline, heavy fuels and hydrogen. The patent made reference to various 20th century nutating engines in the United States, but no reference at all to the original Dakeyne engine, described below, in its prior art. The similarity to its 166 year old hydraulic predecessor is strikingly evident however, the main change being that the disc is not entirely flat but slightly convex. A single prototype has been run briefly under its own power, with a power to weight ratio equal to those of typical current four stroke engines. It is claimed by the authors of the developer/US Army /NASA technical evaluation report, that a production version of the new engine (for UAV applications) might provide a power to weight ratio of 1.6 hp/lb or 2.7 kW/kg . This is slightly better than current automotive production engines , but nowhere near the Graupner G58 or the Desert Air DA 150 .

A company called McMasters, previously headed by successful American entrepreneur Harold McMaster is also developing a nutating motor burning a mixture of pure hydrogen and pure oxygen that, it claims, will give 200 hp but weigh only one-tenth that of gasoline/air production automotive engines with the same power output. So far the McMasters company claims to have spent $10 million on its development. Plans are also being made to develop a version "the size of a coffee can" that can be built directly into wheel hubs, eliminating the traditional drive train entirely. This concept was first attempted in the British Leyland Mini Moke but was, at that time, severely hampered by lack of reliable synchronization - which is now more commonplace because of ubiquitous miniaturized embedded modern day computer chips. A gasoline-powered version is also planned by McMasters, which is claimed to give substantially cleaner operation than traditional engines .

History

The principle underlying the current engine design was first demonstrated and utilized in a high pressure water driven engine & pump invented in the early 19th century in Darley Dale, Derbyshire by two young brothers and patented in 1830 England by their father, Daniel Dakeyne (Dakin), a solicitor and antiquarian who also owned a flax mill powered by his sons' hydraulic engine known locally as "The Romping Lion". It had only one moving part. (Patent number 5882). Power output was estimated to be around 35 hp.

The same two sons had previously, while still just teenagers in 1794, also invented "The Equalinium", a machine for the preparation of flax for spinning.

Frank Nixon in his book "The Industrial Archaeology of Derbyshire" (1969) commented that "The most striking characteristic of this ingenious machine is perhaps the difficulty experienced by those trying to describe it; the patentees & Stephen Glover only succeeded in producing descriptions of monumental incomprehensibility". Although successful, and a larger model was constructed to drain lead mines at Alport near Youlgreave and many steam versions were subsequently built, the advent of more conventional steam powered machines resulted in the design being largely forgotten.

The same geometry and concept is still used in household water meters.