Load Moment Control Damping for Wheel Loader Stability

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Solution Overview

Problem

Existing mobile work machines, such as wheel loaders, face instability issues when operating on uneven ground, leading to false triggering of load moment control systems, which restrict movement and burden operators with unnecessary warnings and reduced overview.

Innovation Solution

A controller is implemented to dampen the load torque signal based on driving speed and other parameters, ensuring the load moment control system remains active while preventing false triggering by adjusting actuating element signals through filtering and threshold management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the load moment control system is completely deactivated above a certain operating speed, then false triggering during movement on uneven ground is prevented, but machine stability can no longer be guaranteed and operator workload increases

Engineering Contradiction:
Improveprevention of false triggeringVSAvoidoperator workload
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The control system dynamically adjusts the damping parameter of the load torque signal based on machine travel speed. At higher speeds, increased damping is applied to prevent false triggering, while at lower speeds, reduced damping maintains system sensitivity for stability control. This parameter adaptation allows the system to operate effectively across different speed ranges without complete deactivation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The control system transitions from a static on/off deactivation approach to a dynamic response where the damping level continuously adapts to travel speed. This dynamic adjustment enables the system to maintain appropriate sensitivity at all speeds, preventing false triggering during high-speed movement while preserving stability monitoring capabilities during low-speed operations.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the load moment control system remains fully active at all speeds, then machine stability is continuously monitored, but false triggering occurs during movement on uneven ground restricting telescopic arm movement

Engineering Contradiction:
Improvetelescopic arm movement freedomVSAvoidmachine stability monitoring
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The damping parameter of the load torque signal is changed based on travel speed conditions. At higher speeds where false triggering occurs due to uneven ground, increased damping filters out spurious signals while maintaining genuine stability monitoring. At lower speeds, reduced damping ensures comprehensive stability control. This resolves the contradiction by adapting system sensitivity to operating conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The damping mechanism acts as an intermediary between the raw load torque signal and the control system's response. By introducing speed-dependent damping, the system mediates between preventing false triggering and maintaining stability monitoring, allowing natural movement variations on uneven ground while still detecting genuine instability conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If speed thresholds are pre-programmed to deactivate the LLMS, then operation is simplified, but the overall overview is reduced and operator concentration is required on stability warnings

Engineering Contradiction:
Improveoperational simplicityVSAvoidoperator overview
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

Instead of pre-programmed speed thresholds that cause abrupt system deactivation, the control system continuously adapts the damping parameter based on real-time travel speed. This creates a smooth transition in system behavior without sudden changes or warnings, maintaining operational simplicity while preserving continuous stability monitoring capability across all speed ranges.

Inventive Principle:
Principle #35Parameter changes

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 solution prevents false triggering of the load moment control system, maintaining stability and reducing operator workload by allowing controlled movement on uneven terrain without complete system deactivation, thus enhancing operational efficiency and safety.

Implementation Method 1

the control system is designed to dampen the load torque signal depending on at least one parameter of the machine

Methodology Applied
Scientific EffectDamping: Damping

Data Source

PatentEP3696137B1Mobile work machine
Publication Date: 2023.03.29 LIEBHERR WERK BISCHOFSHOFEN GMBH
  • EP3696137B1 patent drawingFigure 1
  • EP3696137B1 patent drawingFigure 2~3a
  • EP3696137B1 patent drawingFigure 3b~3c

AI summary

The present invention relates to a mobile working machine (1), in particular a wheel loader, with a vehicle structure and with a telescopic arm arranged thereon, wherein a lifting cylinder (4, 18) is provided for raising and lowering the telescopic arm and a telescoping cylinder (5) for extending and retracting the telescopic arm, with a load moment system for determining a load moment signal, with a speed sensor with sensor technology for determining the travel speed of the working machine, and with a control element (12) for generating a control element signal, on the basis of which an actuating element signal is generated which serves to control the cylinder(s), wherein a control unit (10) is provided which is configured to dampen the load moment signal depending on one or more parameters of the working machine and which is further configuredto reduce or interrupt the actuator signal, at least in certain areas, depending on the damped load torque signal.