Five-stroke engine


The five-stroke engine is a compound internal combustion engine patented by Gerhard Schmitz in 2000.[1] Schmitz's concept is being developed by Ilmor Engineering. Ilmor's prototype is an internal combustion engine that uses a solid cylinder block with electric motors driving the oil and water cooling pumps. The prototype uses two overhead camshafts with standard poppet valves. The five-stroke prototype engine is turbocharged. The goal of the five-stroke engine is to have higher efficiency with lower fuel use. In order to increase efficiency, a secondary cylinder is added as an expansion processor to extract more energy from the fuel.

Gerhard Schmitz's concept engine uses two high pressure (HP) fired cylinders with standard four-stroke engine power cycles. The exhaust gas from the two HP work cylinders is fed into a one larger central low pressure (LP) expansion cylinder. The hot exhaust is used to produce more power.

The operation of a 5-stroke SI engine.
1 – Induction
2 – Compression
3 – Power
4 – Initial Exhaust/Re-expansion
5 – Final Exhaust

The low pressure expansion cylinder is adjustable to maintain the best expansion ratio, regardless of the compression ratio. The prototype has produced very good fuel consumption over a standard gas engine, by about 10%.[2][3][4][5][6]

This concept is similar to that of compound steam engines, which expand steam in high pressure cylinders before exhausting it into low-pressure cylinders in order to extract more energy from the steam. Nicolaus Otto built in 1879 a 5-stroke engine with same arrangement as Ilmor, but customers returned it due to poor performance. 'The romance of engines', T Suzuki, SAE, pp 87–93.[7] Two Spanish patents, ES0156621, F Jimeno-Cataneo, 1942; and ES0433850, C Ubierna-Laciana, 1975; describe 5-Stroke engines identical to that of Gerhard Schmitz, this engine had a fellowship to Burgundy University to be studied. JW Eisenhuth patented, US640890, 1900, an 'Air and gas engine', with double expansion. A car with this engine was in exhibition in Harrah collection, fate of car after the collection was dismantled is unknown.

Applications

A planned motorcycle design from Ilmor Engineering 1,478 cc totally 3 cylinder (HP and LP cylinders) uses a five-stroke engine.

Advantages
  • For a gasoline engine, the engine has an expansion ratio near that of diesel engine, about 14.5:1.
  • Adjustable compression.
  • Higher mean effective pressure with less fuel, due to expansion cylinder.
  • Use standard engine parts, no special one of a kind parts.
  • In theory, additional water injection can be used for cooling the cylinder walls. It leads to quick steam expansion and can increase the efficiency of the expansion cylinder.

Disadvantages
  • Increased costs due unique design. Not yet mass-produced.
  • Two different cylinder sizes.
  • More complex than 2 cylinder engine.

Specification
  • Current prototype is for motorcycle use.
  • 3 cylinder (two high pressure and one low pressure)
  • 700 cc 2 HP cylinder
  • 1478 cc total 3 cylinders (HP and LP)
  • 130 horsepower @ 7000rpm
  • 166 Nm @ 5000rpm
  • 226g/kWh BSFC

See also

References
  1. Google Patents, Five-stroke internal combustion engine, US 6553977 B2, filled Oct 26, 2001
  2. Ilmor, 5 Stroke Engine
  3. Five stroke engine animation
  4. 5-stroke-engine.com, The five-stroke concept – ingeniously simple, simply ingenious
  5. autoevolution.com, Five-Stroke Engine Works and Might Enter Production. 26 Sep 2014, by Gabriel Brindusescu
  6. Ilmor 5 Stroke Engine – 700cc Turbo 3 Cylinder – 130 bhp, Better Mileage, Less Weight, By Paul Crowe
  7. Suzuki, Takashi (May 1997). "The Romance of Engines": 87–93. doi:10.4271/r-188. {{cite journal}}: Cite journal requires |journal= (help)
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