Hydrostatic Pump Wear Diagnosis Using Torque-Based Leak Separation

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Solution Overview

Problem

Current methods for determining the state of wear in hydrostatic machines lack accuracy, particularly during operation, and fail to differentiate between wear caused by the machine itself and leaks in the hydraulic system, leading to incorrect wear assessments.

Innovation Solution

A method that determines the current state of wear by calculating the ratio of actual torque to calculated torque using a multivariate regression, physical model, or machine learning module, considering drive vector parameters such as torque, volume flow, and fluid properties, to provide a health index and identify the source of wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If flow rate measurement is used to determine wear, then wear can be detected, but leaks in other hydraulic components cannot be distinguished from pump wear

Engineering Contradiction:
Improvewear detection accuracyVSAvoidsource identification accuracy
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The diagnostic approach is segmented into multiple independent measurement components: actual flow rate measurement, calculated flow rate determination, and torque measurement. By dividing the diagnostic process into these separate segments, the system can isolate and identify the specific source of performance degradation - whether it's pump wear or leaks in other components - rather than treating it as a single undifferentiated flow rate issue.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces torque measurement as an intermediary parameter to differentiate between pump wear and system leaks. By measuring torque and using it to calculate a reference flow rate, the system creates an intermediate diagnostic layer that helps identify the specific source of the problem. The comparison between actual flow rate and torque-based calculated flow rate serves as an intermediary diagnostic step that reveals whether the issue is internal pump wear or external leaks.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If wear measurement is performed during operation, then maintenance can be optimized, but accurate wear assessment becomes difficult due to varying operating conditions

Engineering Contradiction:
Improvemaintenance efficiencyVSAvoidwear measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system compensates for varying operating conditions by dynamically adjusting diagnostic parameters. It measures actual operating parameters (torque, speed, fluid temperature, pressure) and uses these to calculate a reference flow rate that accounts for the current operating state. This parameter adaptation allows accurate wear assessment across different operating conditions, enabling continuous monitoring without requiring standardized test conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The diagnostic system is designed to be universally applicable across different operating conditions and hydraulic system configurations. By using multiple measurement parameters (flow rate, torque, speed, temperature, pressure) and a comprehensive diagnostic algorithm, the system can accurately assess wear regardless of the specific operating point or system setup, making it a multi-functional diagnostic solution.

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

Data Source

PatentEP4150235B1Method for determining a present state of wear of a hydrostatic machine
Publication Date: 2024.09.25 MOOG GMBH
  • EP4150235B1 patent drawingFigure 1~2
  • EP4150235B1 patent drawingFigure 3
  • EP4150235B1 patent drawing

AI summary

The present invention relates to a method for determining a present state of wear of a hydrostatic machine during the operation of the hydrostatic machine. The hydrostatic machine comprises a drive with variable rotational speed and comprises a hydrostatic pump, wherein the drive is designed to drive the hydrostatic pump in order to generate a volume flow of a fluid, and wherein the hydrostatic machine is connected to a fluid transport channel in which the fluid is transported in a manner driven by the hydrostatic machine. The method has a step for determining a first torque of the drive in the case of a specified drive vector. Furthermore, the method has a step for ascertaining a second torque of the drive in the case of the specified drive vector using a first calculation method, and furthermore, the method has a step for determining the present state of wear of the hydrostatic machine using a second calculation method in order to correlate the first determined torque with the second ascertained torque.