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Construction equipment machines today benefits from hydraulic system due to high power density. And, the development of an excavator using “open-center system with spool valves”, in general, requires iterative hardware design tuning activities for optimized performance and fuel economy while matching operator’s commands. Instead of traditional hydraulic and multi-body dynamic simulation with an operator simulation model, this paper focuses on the methodology development of real-time simulation model for an excavator, including the hydraulic system of an excavator’s boom, arm, bucket, and travel as well as multi-body dynamic system. The real-time capability is realized by reducing unnecessary compressible units and achieving numerical stability at sudden pressure changes when valves open and close. The real-time simulation model has been verified later with an actual Volvo CE excavator machine, and the correlation was quite satisfactory.

Due to the high demand of fuel efficient construction equipment, significant research effort has been dedicated to improving excavator efficiency. Among various possibilities, methods to recuperate energy during cab swing motion have been widely examined. Electric and hydraulic hybrids designs have shown to greatly improve fuel efficiency but require drastic design changes. The redesigned systems thus require many hours of operation to offset the manufacturing costs with fuel savings. In this research, a relatively simple swing energy recuperation system is presented using an additional accumulator, fixed displacement hydraulic motor, and control valves. With the system, hydraulic fluid is stored in an accumulator, and a simple controller opens a valve to allow the stored energy to assist the engine in running the main pumps.

The objective of the present work was to investigate a rapid method of obtaining the convection velocity of the bulk gas near the spark plug gap of a firing engine at the time of ignition. To accomplish this, a simple model was developed which utilized both the secondary current and voltage signals, from a conventional spark discharge. The model assumed the spark path was elongated in a rectangular U-shape by the flow. Based on experimentally measured electrical signals the mean convection velocity was computed. The convection velocity calculated by the model first needed calibration which was accomplished with a bench test that used a hot wire anemometer. The technique has a weak correlation at low velocities of 1-2 m/s, but correlates well at higher velocities up to 15 m/s.