Vehicle Chassis Level Control During Braking

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Solution Overview

Problem

Vehicle level control systems in heavy vehicles exhibit undesirable behavior during braking, leading to overcompensation or insufficient compensation of chassis levels when the system is either disengaged or activated, resulting in unsatisfactory chassis positions after stopping.

Innovation Solution

A method that deactivates the vehicle level control system during deceleration and reactivates it after a predetermined period once the vehicle has stopped, allowing for comparison with a target level and adjustment to achieve the desired chassis position, thereby preventing overcompensation and ensuring the vehicle returns to a stable level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the vehicle level control system is activated during braking, then the chassis level is compensated for increased front axle pressure, but the chassis level becomes overcompensated and too high at the front once the vehicle stops

Engineering Contradiction:
Improvechassis level precisionVSAvoidchassis level stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The control system deactivates the level control during braking before the braking maneuver completes, preventing the system from making adjustments that would lead to overcompensation. This preliminary deactivation avoids the harmful effect of overcompensation that would occur if the system remained active throughout the braking event.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The control system operates in periodic cycles, being deactivated during braking periods and reactivated after braking completes. This periodic on/off operation allows the system to adapt to changing vehicle dynamics conditions, avoiding continuous control actions that would cause overcompensation while ensuring level control is restored when appropriate.

Inventive Principle:
Principle #19Periodic action

2Reliability

If the vehicle level control system is deactivated during braking, then overcompensation is avoided, but the increased pressure on the front axle results in a vehicle with too low a chassis level at the front once stopped

Engineering Contradiction:
Improvechassis level stabilityVSAvoidchassis level precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The control system continuously monitors vehicle braking status and uses this feedback to determine when to deactivate and reactivate the level control. By detecting the braking condition and the subsequent stop condition, the system timing its deactivation and reactivation accordingly, ensuring the chassis level is properly adjusted after braking without overcompensation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system reactivates the level control after a predetermined period following the detection of vehicle stop during braking. This delayed reactivation allows the suspension system to settle from the braking-induced pressure changes before the level control begins adjusting, preventing overcompensation while ensuring proper level restoration.

Inventive Principle:
Principle #10Preliminary action

3Use of energy by stationary object

If the vehicle level control system remains active during deceleration, then continuous level control is maintained, but the system exhibits improper behavior and disengages during braking

Engineering Contradiction:
Improvecontinuous control operationVSAvoidsystem behavior stability
Core Design Contradiction:
Use of energy by stationary objectVSReliability

Solution Approach 1:

The control system dynamically adjusts its operational state based on vehicle conditions, transitioning from active to inactive during braking and back to active after braking. This dynamic adaptation to changing vehicle dynamics during deceleration and braking maneuvers prevents improper system behavior while maintaining control when appropriate.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2280839B1Method and system for controlling the level of a vehicle chassis
Publication Date: 2013.11.20 SCANIA CV AB
  • EP2280839B1 patent drawingFigure 1A
  • EP2280839B1 patent drawingFigure 1B
  • EP2280839B1 patent drawingFigure 2A~2C

AI summary

The present invention relates to a method of controlling the level of a vehicle chassis with respect to at least one vehicle axle, the said vehicle comprising a vehicle level control system, wherein the said vehicle level control system is deactivated during deceleration, the method comprising the steps of, when the vehicle has stopped and the vehicle brake is still applied, reactivating the vehicle level control system after a first period of time, and when reactivating the said vehicle control system, comparing the vehicle chassis level with a target level with respect to at least one axle, and increasing and/or decreasing the vehicle chassis level with respect to the said at least one axle based on the said comparison, so that the vehicle level becomes substantially equal to the said target level. The invention also relates to system and a vehicle.