Ricardo shows KERS for diggers at bauma 2013
KERS is no longer the domain of Formula One
Engineering firm Ricardo is part way through a research programme to develop an advanced energy recovery system that can be integrated into an excavator’s hydraulic system.
Known as the High Efficiency Excavator (HFX) project, the system uses a 5kg carbon fibre flywheel that is encased in a vacuum-sealed cartridge, which contributes to minimising friction. The flywheel is spun at speeds of up to 30,000rpm using a magnetic coupling, which is driven from a hydraulic motor.
Power for the hydraulic motor comes from oil returning from the hydraulic system – so energy can be recovered from boom lowering, dipper extension and slewing, for example. The faster the flow of oil through the motor, the greater rotational speed achieved by the flywheel.
Energy is returned to the hydraulic system simply from using the flywheel and its magnetic coupling to then drive the hydraulic motor and assist the engine in powering the hydraulic system. Peak power from the flywheel system can be as high as 100kW, but the progressive release of flywheel energy allows a controlled amount of power to be put back into the system for short bursts.
Ricardo said the system is low cost compared to super-capacitors and battery packs, and suffers no performance degradation over its lifetime. It can be retro-fitted to almost any excavator.
Fuel savings from a 24tonne excavator operating 1,500hours/year can recover the cost of the flywheel energy recovery system within a year, said the firm.