Six Stroke Engine | List Of Research And Development For Six Stroke Engine

                              The six-stroke engine is a type of internal combustion engine based on the four-stroke engine, but with additional complexity to make it more efficient and reduce emissions. Two different types of six-stroke engine have been developed since the 1990s:

In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke. The pistons in this type of six-stroke engine go up and down three times for each injection of fuel. There are two power strokes: one with fuel, the other with steam or air.(Source From: Wikipedia)

The currently notable designs in this class are:

1.The Crower six-stroke engine, invented by Bruce Crower of the U.S. 

In a six-stroke engine developed in the U.S. by Bruce Crower, fresh water is injected into the cylinder after the exhaust stroke, and is quickly turned to superheated steam, which causes the water to expand to 1600 times its volume and forces the piston down for an additional stroke.This design also claims to reduce fuel consumption by 40%. Maximum efficiency would theoretically be obtained by applying the design to a non-turbocharged diesel engine, where the high compression ratio would allow greater expansion of the steam.

The Crower six-stroke engine was invented in 2004 by 75 year old American inventor Bruce Crower who has applied for a patent on a design involving fresh water injection into the cylinders. As of May 2008, no patent has been awarded.  Leonard Dyer invented the first six-stroke internal combustion water injection engine in 1915, which is very similar to Crower's design. Crower's six-stroke engine features:

• No cooling system required
• Improves a typical engine’s fuel consumption
• Requires a supply of distilled water to act as the medium for the second power stroke.

2.The Bajulaz engine by the Bajulaz S.A. company of Switzerland

The Bajulaz six-stroke engine is similar to a regular combustion engine in design. There are however modifications to the cylinder head, with two supplementary fixed capacity chambers: a combustion chamber and an air preheating chamber above each cylinder. The combustion chamber receives a charge of heated air from the cylinder; the injection of fuel begins an isochoric burn which increases the thermal efficiency compared to a burn in the cylinder. The high pressure achieved is then released into the cylinder to work the power or expansion stroke. Meanwhile a second chamber which blankets the combustion chamber, has its air content heated to a high degree by heat passing through the cylinder wall. This heated and pressurized air is then used to power an additional stroke of the piston.

The claimed advantages of the engine include reduction in fuel consumption by at least 40%, two expansion strokes in six strokes, multi-fuel usage capability, and a dramatic reduction in pollution.

The Bajulaz Six-Stroke Engine was invented in 1989 by the Bajulaz S A company, based in Geneva, Switzerland; it has U.S. Patent 4,809,511 and U.S. Patent 4,513,568.

The Bajulaz six-stroke engine features:

• Reduction in fuel consumption by at least 40%
• Two expansion (work) strokes in six strokes
• Multifuel, including liquefied petroleum gas
• Dramatic reduction in air pollution
• Costs comparable to those of a four-stroke engine

3. The Velozeta Six-stroke engine built by the College of Engineering, at Trivandrum in India.

In a Velozeta engine, during the exhaust stroke, fresh air is injected into the cylinder, which expands by heat and therefore forces the piston down for an additional stroke. The valve overlaps have been removed and the two additional strokes using air injection provide for better gas scavenging. The engine seems to show 40% reduction in fuel consumption and dramatic reduction in air pollution. Its specific power is not much less than that of a four-stroke petrol engine. The engine can run on a variety of fuels, ranging from petrol and diesel to LPG. An altered engine shows a 65% reduction in carbon monoxide pollution when compared with the four stroke engine from which it was developed.

The Velozeta engine features are:

• Reduction in fuel consumption
• Dramatic reduction in pollution
• Better scavenging and more extraction of work per cycle
• Lower working temperature makes it easy to maintain optimum engine temperature level for better performance
• The six-stroke engine does not require significant modification to existing engines.
• Better cooling due to additional air strokes, which mostly removes the need for a cooling system
• Lighter engine

This six-stroke engine was developed by and awarded the 'Indian Society for Technical Education - National awarded' for Best B. Tech project of 2006. (ISTE/BBSBEC-B.Tech./Award/2006) The technology is being developed by Velozeta, a Technopark (Trivandrum) supported by the National Institute of Technology based in Calicut. Velozeta has been awarded a Phase-I research grant from the Department of Scientific & Industrial Research (Govt. of India) under the Technopreneur Promotion Programme (TePP).

                          The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine but also increases the compression ratio. The currently notable designs in this class include two designs developed independently: the Beare Head engine, invented by Australian Malcolm Beare, and the German Charge pump, invented by Helmut Kottmann.

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