Energy Optimized Pressure Controlled Clamping System for Continuously Variable Chain Transmissions

A high potential for an improved overall efficiency of a chain converter transmission can be achieved by optimizing the clamping and ratio hydraulics. A new pressure controlled system was developed, which controls oil pressure and flow on demand. This leads to a significant reduction of the required hydraulic energy, thus making a chain converter transmission competitive against hydrostatic-powersplit tractor drive trains in terms of efficiency. Different cycles for passenger cars as well as for tractors show a saving of hydraulic power up to 96% compared to the former constant flow hydraulics. Further energy savings can be achieved by reducing pressure and therefore clamping forces closer to clamping force requirements.