Multi-Axle Differential Locking for Wheel Slip and Maneuverability

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Solution Overview

Problem

Existing methods for controlling driving dynamics in work machines, such as agricultural and construction vehicles, are inadequate in managing wheel slip and traction across multiple axles, particularly in varying environmental conditions, leading to reduced maneuverability and increased wear.

Innovation Solution

A method that involves detecting current wheel speeds, comparing them to permissible speeds, and issuing control signals to lock or unlock differential gears based on wheel slip conditions, with predictive locking of additional axles before entering areas with reduced traction, and adjusting locking durations based on driving dynamics and traction data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If differential gears are locked to prevent wheel slip, then traction and driving dynamics improve, but maneuverability and flexibility deteriorate

Engineering Contradiction:
ImprovetractionVSAvoidmaneuverability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements dynamic control of differential gear locking by continuously monitoring wheel speeds and adjusting the locking state in real-time. The control device locks differentials when wheel slip is detected and unlocks them when slip is prevented, creating a dynamic system that adapts to changing traction conditions rather than maintaining a fixed locked or unlocked state

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system employs periodic monitoring of wheel speeds and periodic adjustment of differential locking states. The control device continuously detects wheel slip conditions and applies locking/unlocking actions at appropriate intervals, creating a rhythmic control pattern that maintains traction while allowing maneuverability when conditions permit

Inventive Principle:
Principle #19Periodic action

2Reliability

If differential gears are locked continuously to prevent wheel slip, then driving dynamics improve, but wear on components increases

Engineering Contradiction:
Improvedriving dynamicsVSAvoidcomponent life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The control device implements periodic locking and unlocking of differential gears based on real-time wheel slip detection. Rather than continuous locking, the system alternates between locked and unlocked states, providing protection only when wheel slip is detected, thereby reducing cumulative wear on differential components while maintaining driving dynamics when needed

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system uses feedback from wheel speed sensors to control the locking state of differentials. The control device monitors wheel speeds, detects slip conditions, and adjusts locking states accordingly. This closed-loop feedback control ensures differentials are locked only when necessary to prevent slip, avoiding unnecessary wear from continuous locking

Inventive Principle:
Principle #23Feedback

3Ease of operation

If wheel slip is allowed to occur, then maneuverability is maintained, but traction is reduced and wear increases

Engineering Contradiction:
ImprovemaneuverabilityVSAvoidtraction
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The control system takes preliminary action by detecting wheel slip conditions early and locking the differential before significant slip occurs. The control device monitors wheel speeds continuously and locks differentials at the first sign of slip, preventing the harmful effects of wheel slip before they can develop fully

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system employs feedback control where wheel speed sensors continuously monitor for slip conditions and provide signals to the control device. The control device responds to this feedback by locking or unlocking differentials to maintain traction while minimizing wear, creating a responsive closed-loop control system

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3947001B1Method for controlling a driving dynamics function of a working machine
Publication Date: 2024.02.28 ZF FRIEDRICHSHAFEN AG
  • EP3947001B1 patent drawingFigure 1~2
  • EP3947001B1 patent drawingFigure 3~4
  • EP3947001B1 patent drawingFigure 5

AI summary

The invention relates to a method for controlling a driving dynamics function of a working machine having at least two vehicle axles, wherein a current wheel rotational speed of at least one wheel is detected and is supplied in a control device for a comparison with a permissible wheel rotational speed of the same wheel, and a wheel slip is calculated therefrom, wherein a control signal for blocking at least one differential gear mechanism is output by the control device when the wheel slip assumes an impermissible value, wherein, periodically for the relevant differential gear mechanism, a control signal for unblocking is output and a renewed comparison of the wheel rotational speeds is performed, wherein a control signal for blocking the relevant differential gear mechanism is output once more when the wheel slip continues to assume an impermissible value, characterized in that a distance along which the value of the wheel slip of the at least one wheel had an impermissible value is detected by using detection means.