What is a “hybrid” machine?

Visually and operationally, there is very little difference between conventional Komatsu excavators and the Komatsu hybrid excavator. However, in a conventional excavator, engine output is converted entirely into hydraulic energy, with only approximately 13.3% of this energy being effectively used during typical operations. The remainder of the energy is discarded as heat due to conversion, pressure and transmission losses. Additionally, potential and kinetic energy generated by work equipment and the upperstructure are not utilised.

In the Komatsu hybrid excavator, engine output is converted into both electrical and hydraulic energy, energy conversion and transmission losses are reduced and kinetic energy of the upperstructure is regenerated.

The main difference between the hybrid technology used in a hybrid automobile and the Komatsu hybrid excavator is in the storage of electricity. Hybrid automobiles require a large amount of electricity at start up and acceleration and then run at a relatively stable engine speed. Batteries are suitable for energy storage in this application; however, the process requires a chemical reaction which is time consuming and wastes energy as heat during recovery.

In contrast, construction machines require frequent engine speed variations and use large amounts of energy in very short periods of time. Therefore, the Komatsu hybrid excavator employs a Komatsu designed “ultra capacitor” (using readily available, proven and reliable off-the-shelf components) to store electrical energy. This uses electrons and ions for charging and discharging, allowing for instantaneous discharge of electricity and very efficient recovery and storage of regenerative power.

The Komatsu hybrid excavator combines a number of unique features to achieve its primary goal of reduced fuel consumption and consequent lower CO2 emissions.

They include:

• Regeneration of electrical power
• Engine-assist for power on demand
• Ultra-low engine idle
• A smaller engine.