Piston Rod Movement Monitoring for Actuator Wear Tracking

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Solution Overview

Problem

Existing monitoring systems for piston rods in pressure medium actuators of moving work machines are difficult to integrate and not well-suited for preventive maintenance, particularly due to the need for sensors within the actuator, which complicates integration and maintenance scheduling.

Innovation Solution

An arrangement using a sensor unit with a 3-axis accelerometer or MEMS-based inertial sensors to monitor the cumulative movement of piston rods, integrating signal processing and wireless communication, and comparing the cumulative movement data with actuator-specific reference values to determine maintenance needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sensors are integrated within the actuator to measure movement, then measurement precision is improved, but device complexity increases and ease of manufacture deteriorates

Engineering Contradiction:
Improvemovement measurement precisionVSAvoidactuator integration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary processing unit that receives raw sensor data from multiple sensors (including position sensors and acceleration sensors) and calculates the cumulative movement based on this data. This intermediary layer simplifies the actuator integration by handling the complex measurement and calculation tasks externally, while still achieving precise movement monitoring through coordinated sensor data processing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple sensors are used to monitor actuator movement, then measurement precision is improved, but ease of operation deteriorates

Engineering Contradiction:
Improvecumulative movement monitoring precisionVSAvoidsystem operation simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent combines multiple sensor inputs (position sensors, acceleration sensors) and their processing functions into a single integrated processing unit. This unit automatically receives data from all sensors, performs the necessary calculations for cumulative movement, and outputs the result, thereby maintaining high measurement precision while simplifying the operational interface to a single unified system.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The processing unit automatically performs the calculation of cumulative movement based on received sensor data without requiring manual intervention. The system self-manages the complex data processing and calculation tasks, presenting a simple operational interface while maintaining precise monitoring capabilities through automated computation.

Inventive Principle:
Principle #25Self-service

3Reliability

If cumulative movement data is continuously monitored and compared with reference values, then reliability is improved, but use of energy increases

Engineering Contradiction:
Improvepreventive maintenance reliabilityVSAvoidmonitoring system energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The monitoring system performs cumulative movement calculations and comparisons with reference values at periodic intervals rather than continuously. The processing unit receives sensor data, calculates cumulative movement, and compares it with predetermined reference values at defined measurement points, thereby maintaining reliable preventive maintenance capability while reducing energy consumption through intermittent operation rather than continuous monitoring.

Inventive Principle:
Principle #19Periodic action

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 easy and automated monitoring of actuator condition, facilitating timely preventive maintenance, reducing unnecessary downtime and maintenance costs, and preventing fluid leaks by detecting wear in seals.

Implementation Method 1

a sensor unit (1) which consists of at least one 3-axis accelerometer (1) which can measure acceleration, movement and inclination

Methodology Applied
Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

a sensor unit with a 3-axis accelerometer or MEMS-based inertial sensors to monitor the cumulative movement of piston rods

Methodology Applied
Scientific EffectMEMS-based inertial sensors: Microelectromechanical Systems

Data Source

PatentEP4347955B1Arrangement and method for monitoring cumulative movement of a piston rod in an actuator
Publication Date: 2025.07.02 PONSSE OY
  • EP4347955B1 patent drawingFigure 1~2
  • EP4347955B1 patent drawingFigure 3~4
  • EP4347955B1 patent drawingFigure 5

AI summary

The present invention relates to an arrangement for monitor¬ ing the movement of a piston rod (5) in a pressure medium operated actuator (2). Then, a movement of a machine part controlled by the pressure medium operated actuator (2) is monitored in a space of time and place in order to produce terminal location data (Px) on each movement of this machine part. The arrangement comprising at least one 3-axis sensor unit (1) determining a position in relation to a gravitational vector and storage means (3) for receiving and storing the terminal location data produced by this sensor unit. From each two successive pieces of terminal location data (Px) pro duced by the sensor unit, a movement distance (Lx) per formed by the piston rod (5) in the actuator is calculated by processing means (4). Calculating means (6) form from each movement distance (Lx) a cumulative total movement dis tance (Ltot) which is compared by monitoring means (7) with a reference value (Lref) entered to the monitoring means in order to monitor the degree of use of the actuator (2).