Sliding Bearing Condition Monitoring Using Model-Based Gap Estimation
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Solution Overview
Problem
Existing methods for monitoring the condition of plain bearings operated with lubricating oil, particularly in wind turbines, face challenges in detecting undesirable operating states without impairing bearing functionality and accurately assessing wear and tear, due to issues with gap thickness measurement and sensitivity of distance sensors.
Innovation Solution
A method using a control unit with physical models (nominal, variable, and error models) to monitor the condition of plain bearings by comparing measured state variables with calculated values, employing sensors to determine gap thickness, temperature, and pressure, and adjusting the operating behavior based on wear models to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distance sensors are used to measure gap thickness in plain bearings, then measurement capability is provided, but sensitivity and measurement precision deteriorate due to the narrow measuring range and touch sensitivity
Solution Approach 1:
The patent replaces mechanical distance sensors with a model-based calculation approach. Instead of using physical sensors to directly measure gap thickness, the system calculates the gap thickness based on measured operating parameters (speed, load, temperature) and a plain bearing model. This substitution eliminates the sensitivity and range limitations of mechanical sensors while maintaining measurement capability.
Solution Approach 2:
The patent introduces a plain bearing model as an intermediary between the measured operating parameters and the gap thickness determination. The model acts as a mediator that transforms easily measurable quantities (speed, load, temperature) into the difficult-to-measure gap thickness, avoiding the need for direct sensing in the narrow gap space.
2Reliability
If sensors are installed to monitor bearing condition, then detection capability is improved, but bearing functionality is impaired due to space constraints and potential interference
Solution Approach 1:
The patent extracts the measurement function from the bearing system itself. Instead of installing sensors within the bearing assembly, the system uses existing sensors located elsewhere in the drivetrain to measure operating parameters, which are then used to calculate bearing gap thickness. This removes the interference issue while maintaining monitoring capability.
Solution Approach 2:
The patent replaces physical sensing within the bearing with a computational approach using a plain bearing model. The model calculates gap thickness from operating parameters without requiring physical sensors in the bearing, thus avoiding any interference with bearing functionality while providing reliable condition monitoring.
3Measurement precision
If model-based calculation is used to determine gap thickness, then measurement precision is improved, but device complexity increases due to multiple models and calculations
Solution Approach 1:
The patent merges the plain bearing model with the control unit's existing processing capabilities. The model integrates operating parameters (speed, load, temperature) and calculates gap thickness in a unified computational framework, combining multiple functions into a single integrated system rather than separate components.
Solution Approach 2:
The plain bearing model serves multiple functions: it calculates gap thickness, monitors bearing condition, predicts wear, and provides early warning of undesirable operating states. This multi-functionality reduces the need for separate systems while maintaining high measurement precision through the same computational core.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective detection of errors and wear in plain bearings, allowing for proactive adjustments to prevent damage and maintain optimal operating conditions, while ensuring robustness and accuracy in monitoring.
Implementation Method 1
heavy shafts are understood to mean, in particular, drive shafts with a shaft diameter between 30 and 300 mm... hydrostatic or hydrodynamic plain bearings for heavy shafts
Implementation Method 2
hydrostatic or hydrodynamic plain bearings for heavy shafts
Implementation Method 3
A plain bearing assembly also includes a sensor that measures the gap width and thus the lubricating film thickness of the lubricating oil in the bearing gap... controls the pump of a pressure lubrication circuit
Data Source
Figure 1~2
AI summary
The invention relates to a method and a system for monitoring the condition of a sliding bearing (1) operated with lubricating oil for a rotating component, in which a physical variable characteristic for the bearing is measured using at least one sensor (2), which variable is supplied to a control unit (ECU) for condition monitoring, comprising the following steps: - determining by means of the control unit (ECU) at least one condition variable (s; T; p) of the sliding bearing (1) and/or of the lubricating oil as an output variable (y) from at least one physical sliding bearing model (N-V-F), to which at least the rotational speed (n) and the torque (M) are supplied as input variables (u), and a dynamic behaviour of the lubricating oil is assigned to these input variables (u); - measuring with at least one sensor (2) a comparative value for at least one of the condition variables (s; T; p); - evaluating, from a comparison of the measured value of the condition variable (s; T; p) with the model-based value for the condition variable (s; T; p) computed as output variables (y), to what extend the physical sliding bearing model (N-V-F) maps the real behaviour of the sliding bearing (1).