Hydraulic Machine Cycle Quantization to Avoid Resonance
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Solution Overview
Problem
Electronically commutated hydraulic machines experience resonance issues and vibrations due to specific fractions of maximum output, particularly at low and high fractions, leading to undesirable shaking and potential damage when active and inactive cycles follow repeating patterns that align with resonant frequencies.
Innovation Solution
The hydraulic machine intersperses active and inactive cycles with variable fractions selected from a plurality of discrete values to avoid generating resonant frequencies, particularly low frequencies, by controlling the low-pressure and high-pressure valves to match the demand signal while allowing for a range of displacement fractions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the machine operates at specific fractions of maximum output using repeating patterns of active and inactive cycles, then the machine can meet demand signals and control output, but resonance effects and vibrations occur at specific frequencies
Solution Approach 1:
The patent applies dynamics by making the active cycle fraction variable rather than fixed. The controller dynamically adjusts the fraction of active cycles based on the demand signal to avoid resonant frequencies. This is achieved by calculating a variable active cycle fraction that changes with operating conditions, thereby preventing the system from settling into repeating patterns that excite resonance while still meeting the required output demand.
2Productivity
If the machine uses occasional active cycles with inactive cycles therebetween to operate at low fractions of maximum output, then the machine can reduce output to match demand, but highly pulsatile flow is generated
Solution Approach 1:
The patent uses dynamics to continuously adjust the active cycle fraction based on the demand signal. Instead of using fixed rare active cycles, the controller dynamically determines the optimal fraction of active cycles needed to meet demand while avoiding resonant frequencies. This dynamic adjustment smooths flow pulsations by distributing active cycles more evenly while still achieving low output fractions when needed.
3Productivity
If the machine operates at high fractions of maximum output with predominantly active cycles, then the machine can meet high demand, but resonance affects occur due to periodic inactive cycles
Solution Approach 1:
The patent applies dynamics by making the active cycle fraction variable and dependent on the demand signal. Even at high output fractions, the controller dynamically adjusts the timing and distribution of inactive cycles to avoid creating repeating patterns at resonant frequencies. This ensures that high output demand is met while preventing resonance effects through continuous adaptation of the cycle pattern.
4Manufacturing precision
If the machine uses repeating patterns of working chamber activation, then the machine can implement specific displacement fractions, but corresponding frequencies of movement and harmonics are generated
Solution Approach 1:
The patent resolves this contradiction by making the active cycle fraction variable rather than fixed. The controller dynamically calculates the fraction of active cycles needed to achieve the desired displacement fraction while avoiding resonant frequencies. This dynamic approach allows precise control of displacement fractions without being constrained to repeating patterns that generate harmful frequencies.
Data Source
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.