The Hilite VCR system

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As a connecting element between piston and crankshaft in the engine, a connecting rod is an essential component of power transmission. In a conventional engine, the length of a connecting rod and thus also the compression ratio is invariable. StepCom® enables engine operation at different compression ratios. Depending on the operating condition, a high compression ratio is selected for optimum efficiency or a low compression ratio for high performance requirements.



Benefits of a variable compression ratio


As the compression ratio increases, the thermal efficiency of the combustion engine rises. In partial load range, efficiency increases with higher compression and fuel consumption decreases. At high loads, mechanical overload due to knocking combustion is avoided by adjusting the low compression ratio. Furthermore, an optimized position of the combustion center reduces the need for fuel enrichment to achieve engine performance. The exhaust gas temperature is lowered and the use of high-temperature-resistant materials in the exhaust gas turbocharger and catalytic converter is reduced. In particular, this also impedes the forming of soot particles. The StepCom® System for varying the compression ratio ensures a high power density while simultaneously increasing efficiency under Realworld Driving Emission (RDE) test conditions.




The Stepcom® principle in detail

Operating principle

In the StepCom® connecting rod, the combustion piston is mounted in an eccentric bearing in the small end. Rotating the eccentric changes the effective length of the connecting rod and results in a new compression volume and therefore compression ratio. The force required to turn the eccentric is applied by the combustion piston with its oscillating mass and the forces created by combustion. This rotation is limited by a lever attached to the eccentric, which is supported by two hydraulic cylinders inside the connecting rod. A hydraulic switch closes or opens the hydraulic cylinders and allows the eccentric to adjust the length of the connecting rod.

Highly adaptable

A great advantage of StepCom® is its modularity. Existing engines can be retrofitted with minor modifications regardless of the engine architecture. StepCom® can be excellently combined with other efficiency-enhancing measures in the engine.

Hilite's consistent "design-to-cost" approach allows StepCom® to be used in a wide range of vehicle classes. The system unfolds its full potential in highly charged gasoline engines, especially with regard to downsizing strategies.

For specific diesel engine applications, StepCom® offers advantages in terms of increased efficiency and exhaust emissions. By lowering the combustion peak pressure and combustion temperature, a design with reduced friction is made possible and the formation of nitrogen oxides is significantly decreased.

An innovative system

StepCom® ls a significant contribution to resource-friendly mobility. Our claim is to combine highest quality with active environmental protection and constant innovation. Are you interested in our products? Then let’s talk. We will be happy to advise you in more detail!

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