Thermal Analysis of the Cylinder Block of an Axial Piston Pump - The Key to Monitoring Efficiency

Abstract

To prepare today's fluid power systems for the future digitalization of the industry, it is necessary to improve the information available regarding the current condition of crucial components of the system. Positive displacement machines, which constitute the core of any hydraulic system, play a vital role in this process. Future smart systems will require more information about the current state of the pump such as power usage and efficiency. Current condition monitoring approaches utilize an array of sensors that need to be sampled at high frequency. The transmission, storage, and post processing of this vast amount of data requires an enormous number of resources, especially if exercised at scale. Previous work conducted at the Institute of Mechatronics Engineering at TU Dresden has demonstrated that measuring the temperature in the lubricating gaps can allow for a deeper insight into the tribological mechanisms in these interfaces. Not only can the gap height, viscous friction and leakage be determined from this information, but also crucial information such as wear level and expected component lifespan can be derived from temperature levels with adequate reference models [1]- [4] This paper demonstrates that monitoring the thermal condition of the cylinder block is an effective approach to estimate the pump's efficiency. This will be illustrated through both simulation and measurement, in addition to the pioneering measurement of the heat convection coefficient on the cylinder block surface, a critical boundary condition for the simulation.To measure the temperature of a moving cylinder block, a 160cc axial piston pump was equipped with a telemetric system, which was specially designed and built for this task. Next to the 20 temperature sensors four heat convection coefficient sensors were also carefully placed inside the cylinder block. The resulting measurements did not only validate the simulation but also give a unique insight into the inner workings of a piston pump.