Electronically Commutated Hydraulic Machine Resonance-Avoiding Cycle Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronically commutated hydraulic machines experience vibrations and resonance issues due to pulsatile flow patterns when operated at specific fractions of their maximum output, leading to undesirable shaking and potential damage, particularly at low and high fractions of maximum displacement.
Innovation Solution
The method involves controlling the hydraulic machine to intersperse active and inactive cycles of working chamber volume, with the fraction of working chambers carrying out active cycles being variable and selected from a plurality of discrete fractions to avoid generating resonant frequencies, particularly low frequencies, by regulating the low- and high-pressure valves to match demand signals while minimizing unwanted vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hydraulic machine operates at specific fractions of maximum output using interspersed active and inactive cycles, then the machine can match output to fluctuating demand, but this generates pulsatile flow and resonance effects at specific frequencies
Solution Approach 1:
The system dynamically adjusts the pattern of active and inactive cycles based on the demanded fraction of maximum output. The controller modifies the timing and distribution of active cycles across working chambers to achieve the desired output while avoiding fixed repeating patterns that cause resonance. This dynamic adaptation allows the system to maintain versatility in matching demand while suppressing harmful vibrations through real-time pattern variation.
2Productivity
If the machine carries out only occasional active cycles at low fractions of maximum output, then the machine can operate at low demand levels, but this creates highly pulsatile flow and low frequency vibrations
Solution Approach 1:
The system employs periodic active cycles distributed across multiple working chambers, where each chamber undergoes active cycles at different phases. By coordinating the periodic action of multiple chambers with different phase angles, the system maintains low output levels while the superposition of multiple periodic flows smooths out pulsations and eliminates low frequency vibrations that would occur with single-chamber periodic operation.
3Productivity
If the machine operates at high fractions of maximum output with predominantly active cycles, then the machine can meet high demand, but this generates resonance effects at frequencies equal to fractions of working chamber actuation frequency
Solution Approach 1:
The system introduces asymmetry in the distribution and timing of inactive cycles among working chambers. Instead of uniform periodic inactivation, the controller assigns inactive cycles asymmetrically across chambers with different phase relationships. This asymmetric pattern breaking prevents the formation of symmetric repeating patterns that would generate strong resonance effects, while still maintaining high overall productivity through predominantly active operation.
4Adaptability or versatility
If repeating patterns of working chamber activation are used to achieve fractional displacement, then the machine can operate at specific output fractions, but this leads to generation of corresponding frequencies of movement and harmonics
Solution Approach 1:
The system dynamically varies the activation patterns of working chambers based on the demanded fractional displacement. Rather than using fixed repeating patterns, the controller continuously adjusts which chambers are active and their timing to achieve the target fraction. This dynamic reconfiguration prevents the establishment of stable repeating patterns that would generate harmful frequencies and harmonics, while maintaining the ability to operate at any fractional displacement level.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A hydraulic apparatus including an electronically commutated machine having a plurality of working chambers which are controlled on each cycle of working chamber volume to carry out active or inactive cycles of working chamber volume allows only a plurality of defined fractions of cycles to be active cycles to avoid generating frequencies of active cycles which cause low frequency resonances. The demand signal may be quantised into fractions m/n where n is an integer below a threshold selected to avoid repeating patterns of active cycles of more than a cut-off length.