Fluid Machine Fault Detection via Dynamic Displacement Control
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Solution Overview
Problem
Fluid-working machines with cyclically varying volume chambers fail to function adequately when one or more working chambers become unavailable due to faults, leading to inadequate output signal management and performance degradation.
Innovation Solution
A method and system for detecting faults in fluid-working machines by analyzing previously selected net displacements of working fluid, using a controller to adjust fluid displacement based on the availability of other working chambers, and employing sensors to monitor output parameters such as pressure and flow rate to determine if they meet acceptable function criteria, thereby treating faulty chambers as unavailable and adjusting operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the machine operates with all working chambers assumed available, then the demand signal can be met under normal conditions, but the output signal becomes inadequate and performance degrades when chambers become unavailable due to faults
Solution Approach 1:
The controller monitors actual fluid output and compares it with expected output based on demand signals. When discrepancies indicate chamber unavailability, the system adjusts valve timing and displacement volumes dynamically to compensate, maintaining reliable operation despite faults
Solution Approach 2:
The control system transitions from static predetermined valve timing to dynamic adaptive timing. The controller continuously adjusts valve opening/closing moments and displacement volumes based on real-time feedback about chamber availability, enabling the system to adapt its operation mode to maintain performance
2Productivity
If the controller dynamically adjusts fluid displacement for each cycle to meet demand, then productivity increases, but the complexity of controlling multiple valves increases
Solution Approach 1:
The control system divides the multi-chamber machine into independently controllable units. Each working chamber's valve timing and displacement can be adjusted individually, allowing selective optimization of each chamber's contribution to overall productivity while managing control complexity through modular segmentation
Solution Approach 2:
The controller dynamically changes operating parameters including valve timing, displacement volume, and cycle frequency for each working chamber. This enables flexible productivity adjustment by optimizing fluid displacement characteristics in response to varying demand conditions
3Adaptability or versatility
If electronically controllable valves are used to regulate fluid flow, then the ability to meet demand signals improves, but the reliability decreases when valves or chambers develop faults
Solution Approach 1:
The control system incorporates fault tolerance by preparing alternative operating modes in advance. When a valve or chamber fault is detected, the system has pre-programmed strategies to redistribute fluid displacement across remaining healthy chambers, cushioning against the reliability impact of individual component failures
Solution Approach 2:
Healthy working chambers are designed to perform multiple functions - both their normal displacement role and a compensatory role when chambers fail. The control system can reassign tasks dynamically, allowing any healthy chamber to increase its displacement volume to compensate for failed chambers, enhancing overall system reliability
Data Source
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AI summary
Disclosed is a method of detecting a fault in a fluid-working machine comprising a plurality of working chambers of cyclically varying volume, each said working chamber operable to displace a volume of working fluid which is selectable for each cycle of working chamber volume to carry out a working function responsive to a received demand signal. An output parameter of the fluid working machine, which is responsive to the displacement of working fluid by one or more of the working chambers to carry out the working function, is measured. It is determined whether the measured output parameter fulfils at least one acceptable function criterion, taking into account the previously selected net displacement of working fluid by a working chamber during a cycle of working chamber volume to carry out the working function. By taking into account the previously selected net displacement of working fluid by a working chamber during a cycle of working chamber volume to carry out the working function, an unacceptable fault in a fluid-working machine may be detected if it causes one or more measured output parameter to respond in a way which would not be expected if the fluid working machine was functioning acceptably.