Towards the Development of a Tribotronic Seal

Abstract

Lip seals play a critical role in rotating machinery across various industries by preventing the egress of process fluids or lubricant from machine elements, and the ingress of dirt or contaminants. This research advances the development of intelligent lip seal technology within the framework of Tribotronics, using various testing methods and an adaptive control system. A novel test apparatus was created, integrating sensors and actuators, thermal imaging, real-time data acquisition, Bluetooth, and Wi-Fi wireless connection protocols for data collection. An actuation system was designed to respond dynamically to changes in temperature and radial pressure to control leakage, and empirical models were developed to correlate key operational parameters with seal performance. Additionally, a control system was developed to optimize seal performance in real-time.

The research involved a series of experiments to characterize seal behaviour under various operational parameters in both lubricated and dry conditions. Testing in these conditions simulates real operating conditions to obtain baseline data in normal (lubricated) and extreme conditions (dry) to determine the seal’s ability to function during lubricant starvation. Testing also included stress relaxation tests, friction measurements, torque analysis, direct temperature measurement, leakage measurements and thermal imaging. Data was collected across a range of speeds, eccentricities, and radial loads, with particular attention to the interplay between these factors.

Key findings include: the establishment of correlations between temperature at the seal-shaft interface and eccentricity or offset, as well as between frictional load and eccentricity, with lower frictional loads observed at greater offsets. It was also found that actuator load is directly related to radial load. Stress relaxation was quantified as a significant factor in seal operation, with relaxation rates influenced by strain history. The research demonstrated that leakage rate is correlated with operating speed and radial load, while friction was observed to peak at startup before settling to lower steady-state levels. Torque was shown to increase proportionally with speed and eccentricity but decrease at specific offsets. Operating temperature stabilized between 55-65°C during normal and moderately eccentric conditions. Additionally, turned shafts exhibited better fluid retention but lower surface bearing indices compared to plunge ground shafts.

The research contributes to knowledge in the field of Tribotronics and intelligent lip seal technology. The contributions include the development of novel test equipment capable of real-time data acquisition and adaptive control. A control algorithm for leakage was introduced, which dynamically adjusts outflow based on radial pressure and shaft rotational speed. Additionally, new empirical findings were generated, providing valuable data on the relationships between operational parameters and seal performance. The research also extends the application of existing tribological principles to enhance the design and control of lip seals, paving the way for more efficient and reliable sealing technologies.