|A rendering of a hybrid excavator. Source: Kobe Steel.|
Nikkei. Komatsu Ltd. plans to introduce a hybrid hydraulic excavator in Japan and overseas this fall. The machine is powered by a combination of an electric motor and diesel engine.
The midsize excavator consumes 30% less diesel than the company’s existing model of comparable size driven only by a diesel engine. It will be priced around ¥12 million (US$99,000) in Japan, 20% higher than the current model.
Komatsu, the world’s second-largest maker of construction machinery, plans to sell a total of 1,500 units in Japan and overseas in fiscal 2010 according to the report in the Nikkei. The company has been working on hybrid construction machinery for a number of years, and was awarded a US Patent on its efforts in 2004.
The excavator uses an engine; a hydraulic pump powered by the engine; hydraulic actuators activated by discharge oil from the hydraulic pump; an electric motor that works in conjunction with the engine to assist in driving the hydraulic pump; an electric generator powered by the engine; and a battery for storing generated electric power.
If the work load of the hydraulic actuators is low and the absorbed torque (the torque of the engine which the hydraulic pump requires in order to drive the hydraulic actuators) of the hydraulic pump is smaller than the output torque of the engine, the extra output torque of the engine actuates the generator so that electric power is generated for storage in the battery.
Komatsu is not alone in its efforts to deliver hybrid construction machinery.
Japan’s Kobe Steel and NEDO (New Energy Development Organization) are undertaking joint development of a prototype hybrid excavator.
New Holland has unveiled a prototype hybrid excavator (called the Hybrid) which offers fuel savings of up to 40% compared to diesel-only units.