Animation of the crankless rotors

Crankless

A new efficient mechanical transmission

Internal combustion engine

Four-stroke engine

A four-stroke engine (or four-cycle engine) is an internal combustion engine in which the working chamber completes four separate strokes which constitute a single thermodynamic cycle. A stroke refers to a full expansion or compression of the working chamber.

Crankshaft design (traditional - one cylinder shown)

Animation of the traditional crankshaft four-stroke engine

(c) Zephyris - Own Work / CC-BY-SA-3.0

Crankless design (new - only one working chamber shown)

Animation of the four-stroke crankless internal combustion engine with 1 working chamber

Four-stroke priciple

1. Intake
This stroke begins at the smalles volume of the working chamber (top dead center in a traditional crankshaft engine). The working chamber expands, increasing its volume. A mixture of air and possibly fuel is forced by atmospheric (or greater by some form of air pump) pressure into the working chamber. In the traditional crankshaft design, the intake flows through a valve and intake port, leading to pressure losses over the intake port. In the crankless design, the intake is much simpler and wider, with no pressure loss.
2. Compression
With both intake and exhaust closed, the working chamber compresses the air or fuel-air mixture. In the traditional crankshaft design, the intake and exhaust valves need to be closed. In the crankless design, the intake and exhaust are closed by design, without the need for any valves.
3. Power
The power stoke starts again close to minimal volume of the working chamber (top dead center in a traditional crankshaft engine). In traditional gasoline engines the compressed air-fuel mixture is ignited by a spark plug. In a diesel engine or gasoline direct injection (GDI) ignition starts after fuel injection into the compressed (and therfore heated) air. The resulting pressure from the combustion of the compressed fuel-air mixture forces the working chamber to expand and delivers the work to power the engine.
4. Exhaust
During the exhaust stroke, the working chamber contracts again to minimum volume while the exhaust is open. This action expels the spent fuel-air mixture. In the traditional crankshaft design, the exhaust flows through the exhaust valve(s), leading to pressure losses and friction. In the crankless design, the exhaust is much simpler and wider, with no pressure loss.

Crankshaft design (traditional - common 4 cylinder configuration)

Crankless design (new - Equivalent 4 working chambers)

Animation of the traditional crankshaft four-stroke engine
Animation of the traditional crankshaft four-stroke engine
Animation of the traditional crankshaft four-stroke engine
Animation of the traditional crankshaft four-stroke engine
Animation of the four-stroke crankless internal combustion engine with 4 working chambers

(c) Zephyris - Own Work / CC-BY-SA-3.0 / Needs to be corrected for 4 different phases

Two-stroke engine

It is also possible to use the crankless design for a two-stoke engine. A main advantage of the two-stoke engine is its excellent power-to-weight ratio, which usually comes at the expense of a suboptimal themodynamic efficiency. However, the power-to-weight ratio of a crankless four-stoke engine is already signifcantly better than in the cranshaft design. Therefore, the crankless four-stroke engine combines the advantages of the traditional four- and two-stroke designs: low weight AND excellent efficiency. To further reduce weight, and achieve maximum power-to-weight ratio at a thermodynamic cost, the crankless design can however equally be used for a two-stroke engine.

Advantages

The main advantages of the crankless internal combustion engine compared to the traditional crankshaft engine are:

Better technology Tangible advantages
4 combustion chambers rotate in one toroid, compared to a separate cylinder for each combustion chamber in the traditional design. Common configuration requires only one toroid vs 4 cylinders in the traditional design.
  • Better power-to-weight ratio
  • Lower weight
  • Smaller size
Much less moving parts: no valves, no camshaft or hydraulic lifting mechanism, ...
  • Lower production cost
  • Simplified serviceability
  • Lower maintenance cost
  • Quiet
  • Low vibration
  • Higher revolution speeds
No pressure loss over the intake or exhaust, as there are no valves.
  • Increased efficiency
  • Easier (super)charging
  • Higher revolution speeds
No back and forth linear movements of pistons.
  • Quiet
  • Low vibration
Higher revolution speeds possible as all components are rotating and the intake and exhaust flows are very fast through large conducts.
  • Better power-to-weight ratio
  • Lower weight
  • Smaller size
  • Scalable
  • Flexible
Only one injector or ignition for four working chambers, compared to 4 injectors or ignition systems in classic 4-cylinder design.
  • Lower production cost
  • Simplified serviceability
  • Lower maintenance cost
Combustion chamber rotates constantly, leading to turbulence in the combustion chamber. High turbulence results in faster and more complete combustion of the air-fuel mix. Less need for complicated cylinder head engineering (CFD).
  • Increased efficiency
  • Lower wasteful emissions
  • Lower production cost

Applications

Possible applications include:

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