Hydraulic Accumulator Pressure Estimation for Degradation Detection
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Solution Overview
Problem
Conventional hydraulic energy recovery apparatuses fail to effectively detect accumulator degradation, leading to increased fuel consumption and potential hydraulic oil spills due to leaked pressurized gas, making it difficult to monitor and maintain the system's performance.
Innovation Solution
A hydraulic energy recovery apparatus equipped with a pressure detector, reset device, and controller that estimates sealed gas pressure and determines accumulator degradation based on elapsed time, number of operations, and pressure changes, allowing for early detection and notification of performance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an accumulator is used to recover hydraulic energy, then fuel consumption is reduced and hydraulic efficiency is improved, but the accumulator may degrade over time causing gas leakage and hydraulic oil spills
Solution Approach 1:
The system performs preliminary detection of accumulator degradation by monitoring pressure changes during operation. The control device detects abnormal pressure variations that indicate seal deterioration or gas leakage before complete failure occurs, allowing preventive maintenance to be scheduled
Solution Approach 2:
The system continuously monitors hydraulic pressure during accumulation and release operations, comparing actual pressure values against expected values. When deviation exceeds a threshold, the control device generates warnings or alerts to notify operators of accumulating degradation, creating a closed-loop feedback system for reliability management
2Measurement precision
If pressure detection is implemented to monitor accumulator status, then degradation can be detected, but system complexity increases
Solution Approach 1:
The control device performs multiple functions: it controls the directional control valve for normal hydraulic operation, monitors pressure during accumulation and release, detects degradation patterns, and generates warnings. By consolidating these functions into a single control device rather than adding separate detection hardware, system complexity is minimized while maintaining comprehensive monitoring capability
Solution Approach 2:
The system uses the existing hydraulic pressure signals during normal operation to self-diagnose accumulator health. The control device analyzes pressure variations that naturally occur during accumulation and release cycles, eliminating the need for separate diagnostic sensors or test procedures. The system monitors its own operational parameters to detect degradation
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 early detection of accumulator degradation, reducing fuel consumption, preventing hydraulic oil spills, and improving the reliability and convenience of the hydraulic energy recovery system by prompting timely replacements.
Implementation Method 1
an accumulator that recovers a part or all of returned oil from the hydraulic actuator
Implementation Method 2
a gas gradually permeates from a seal ring between a piston outer peripheral surface and a cylinder inner peripheral surface
Implementation Method 3
a pressure detector that detects a pressure of the accumulator
Implementation Method 4
a sealed gas pressure estimating section that estimates a sealed gas pressure of the accumulator from a rising state of an accumulator pressure in a case of starting accumulation from a state where the accumulator pressure is equal to a tank pressure
Implementation Method 5
a gas gradually permeates from a seal ring between a piston outer peripheral surface and a cylinder inner peripheral surface
Implementation Method 6
the sealed gas pressure in the accumulator gradually reduces, and in some cases, a so-called performance degradation occurs
Data Source
AI summary
A controller (45) is provided with an elapse time measuring section (47A) that measures an elapse time (tx) elapsed since an initial use of an accumulator (29) based upon a reset signal from a reset switch (44), a number-of-operations measuring section (47B) that measures a number of operations of the accumulator (29), that is, a number (N) of boom lowering operations after a reset, based upon a detection signal from an accumulator side pressure sensor (39), a gas permeation amount estimating section (47C) that estimates an estimation gas permeation amount (Qloss) of the accumulator (29), a sealed gas pressure estimating section (47D) that finds an estimation sealed gas pressure (Pgs) of a gas chamber (29B) of the accumulator (29), and an accumulator degradation determining section (47E) that determines a degradation condition of the accumulator (29) and outputs the determination result.