Interaxle Lock Deactivation During Braking

Solution Overview

Problem

Existing methods for deactivating interaxle locks during braking processes, particularly in anti-lock braking systems, are inefficient, leading to delayed deactivation and potential vehicle stability issues, especially in semi-trailer tractors.

Innovation Solution

A method involving a time-delayed ramp-like increase in setpoint pressure to deactivate the interaxle lock, allowing for zero torque transmission and disengagement, especially during emergency braking situations, while maintaining normal braking behavior in non-emergency conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the interaxle lock is activated to synchronize driven axles, then traction is improved, but deactivation is delayed due to tensions in the drive train

Engineering Contradiction:

ImprovetractionVSAvoiddeactivation delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The control unit preemptively deactivates the interaxle lock upon detecting braking activation, before the braking process fully engages. This preliminary action prevents the lock from remaining activated due to drive train tensions, thereby resolving the deactivation delay while maintaining traction during the braking event

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the activation state of the braking device and uses this feedback to control the interaxle lock. When braking is detected, the control unit responds by deactivating the lock, creating a closed-loop control system that adapts the lock's state based on real-time braking conditions

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If the interaxle lock remains activated during braking, then axle synchronization is maintained, but vehicle stability is compromised

Engineering Contradiction:

Improveaxle synchronizationVSAvoidvehicle stability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The control unit preemptively deactivates the interaxle lock upon detecting braking activation, before the braking process fully engages. This preliminary action prevents the lock from remaining activated due to drive train tensions, thereby resolving the deactivation delay while maintaining traction during the braking event

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the activation state of the braking device and uses this feedback to control the interaxle lock. When braking is detected, the control unit responds by deactivating the lock, creating a closed-loop control system that adapts the lock's state based on real-time braking conditions

Inventive Principle:

Principle #23Feedback

3Reliability

If the interaxle lock is deactivated during emergency braking, then vehicle stability is improved, but braking performance is reduced

Engineering Contradiction:

Improvevehicle stabilityVSAvoidbraking performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system applies partial braking force to the driven axles during emergency braking, rather than full braking force. This partial action is sufficient to maintain vehicle stability and control while preventing the interaxle lock from tensing up, thereby avoiding the need to reduce overall braking performance

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP2644427B1Control of multiple driven axles of a motor vehicle

Publication Date: 2015.04.08 ZF CV SYST HANNOVER GMBH

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AI summary

The method involves determining set pressure for front axle (3) and rear axle (5) in dependence on braking request size (9). The braking force on front and rear axles acting timing chains for setting first and second actual pressure is controlled in response to set pressure respectively. The time-delayed braking is raised to second axles due to second actual pressure of second timing chain. The rotation speed-synchronizing of longitudinal barrier switched between axles is released during time-delayed raising of second actual pressure so as to deactivate synchronization propelled axles.