Hydraulic Circuit Health Monitoring Using Temperature Deviation

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Solution Overview

Problem

Current methods for determining the health status of hydraulic circuit arrangements are either inefficient due to reliance on fixed maintenance schedules or require excessive sensor data, which can be costly and prone to errors.

Innovation Solution

A method using temperature sensors to compare actual hydraulic fluid temperature with expected values, potentially supplemented by additional data from control inputs, databases, or sensors, to determine health status levels such as remaining operability hours or maintenance recommendations, minimizing the need for additional sensors and focusing on existing hardware modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors are used to measure actual wear of components, then measurement precision of component wear is improved, but device complexity and cost increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses temperature as an intermediary parameter to indirectly measure component wear. Instead of directly measuring wear with complex sensors, the system monitors hydraulic fluid temperature, which changes as components wear. This intermediary approach allows wear detection using simple, existing temperature sensors while avoiding the complexity of direct wear measurement devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical wear measurement systems with a thermal-based detection system. By substituting direct mechanical wear sensors with temperature monitoring, the system achieves wear measurement functionality using a different physical domain (thermal instead of mechanical), thereby reducing device complexity and leveraging existing temperature sensing infrastructure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If additional sensors are installed to monitor component wear, then reliability of health status determination is improved, but loss of substance and mounting space requirements increase

Engineering Contradiction:
ImprovereliabilityVSAvoidloss of substance
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent makes temperature sensors serve multiple functions: they monitor both hydraulic fluid temperature for operational control and serve as indicators of component wear for health status determination. This multi-functionality allows the system to achieve reliable wear monitoring without adding dedicated sensors, thereby avoiding additional mounting space requirements and sensor-related costs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If fixed maintenance schedules are used, then ease of operation is improved, but productivity decreases due to unnecessary maintenance

Engineering Contradiction:
Improveease of operationVSAvoidproductivity
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent transitions from static, fixed maintenance schedules to dynamic, condition-based maintenance scheduling. By continuously monitoring temperature data and comparing it against expected values, the system dynamically adjusts maintenance timing based on actual component condition. This allows maintenance to be performed only when necessary, eliminating unnecessary downtime and maintaining high productivity while keeping operations simple through automated monitoring.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback mechanism where temperature measurements are continuously compared against expected values, and the results feed into health status determination and maintenance scheduling decisions. This closed-loop feedback system automatically adjusts maintenance timing based on actual component condition, replacing the open-loop fixed schedule approach. The feedback enables the system to maintain ease of operation while optimizing productivity by avoiding unnecessary maintenance interventions.

Inventive Principle:
Principle #23Feedback

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

This approach provides a precise and cost-effective means to assess hydraulic circuit health, reducing unnecessary maintenance and sensor costs while ensuring reliability, and can be easily integrated into existing systems.

Implementation Method 1

at least one temperature sensor (12)

Methodology Applied
Scientific EffectTemperature measurement: Thermocouple

Data Source

PatentEP3935285B1Method for determining the health status of the hydraulic circuit arrangement
Publication Date: 2025.03.26 DANFOSS POWER SOLUTIONS INC
  • EP3935285B1 patent drawingFigure 1
  • EP3935285B1 patent drawingFigure 2~3
  • EP3935285B1 patent drawingFigure 4

AI summary

The invention relates to a method (25) of determining the health status of a hydraulic circuit arrangement comprising at least one hydraulic fluid working machine (2, 3). The health status is determined (29) using at least in part an actual temperature information (12) of the hydraulic circuit arrangement (1) that is compared to an expected temperature information (24) of the hydraulic circuit arrangement (1).