Dynamic Tolerance Adjustment for Bus Pneumatic Suspension Level Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In city and intercity buses, passengers experience unpleasant and annoying height fluctuations of the vehicle body when getting on and off, particularly at the front entrance door, due to noticeable changes in the step threshold height, which are not immediately corrected by existing level control systems.
Innovation Solution
The method involves detecting the driving speed and parking brake status, along with the open state of entrance doors, to adjust the tolerance limits of air spring bellows on at least one vehicle axle or side, lowering the upper tolerance limit or raising the lower tolerance limit during bus stop operations to minimize height fluctuations at the entrance doors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tolerance limits of air spring bellows are kept wide to avoid frequent corrections during normal operation, then driving comfort is improved, but height fluctuations at entrance doors become noticeable and annoying to passengers
Solution Approach 1:
The tolerance limits are made dynamically adjustable based on the operating state of the vehicle. During bus stop operations when doors are open, the tolerance limits are narrowed to reduce height fluctuations. During normal driving, wider tolerance limits are used to maintain comfort and reduce unnecessary corrections. This dynamic adaptation resolves the contradiction by changing the control parameters according to the specific operational context.
Solution Approach 2:
The control system changes the tolerance limit parameters based on detected operating conditions (driving speed, door status). When the vehicle is stationary and doors are open, the upper tolerance limit is lowered and/or the lower tolerance limit is raised, creating a narrower tolerance band that triggers corrections at smaller deviations, thereby reducing noticeable height fluctuations at the entrance door while maintaining comfortable operation during transit.
2Object-affected harmful factors
If the tolerance range is reduced to correct smaller deviations, then height fluctuations are minimized, but control processes become more frequent and noticeable to passengers
Solution Approach 1:
The system dynamically adjusts tolerance limits based on whether the vehicle is in motion or stationary. Narrow tolerance limits are applied only during bus stop operations when doors are open, while wider limits are used during normal driving. This temporal separation ensures that frequent corrections occur only when necessary and when passengers are already aware of the stationary state, avoiding noticeable disturbances during transit.
Solution Approach 2:
The system proactively narrows tolerance limits before passengers board or alight by detecting when the vehicle is stationary and doors are open. This preliminary adjustment prevents height fluctuations from becoming noticeable to passengers, as the corrected level is maintained before the boarding/alighting process completes, rather than reacting to already-visible fluctuations.
3Manufacturing precision
If the upper tolerance limit is lowered and/or lower tolerance limit is raised during bus stop, then height control precision is improved, but the system complexity increases due to additional detection requirements
Solution Approach 1:
The control system utilizes existing sensors already present in the bus (speed sensors, door position sensors, parking brake sensors) for the dual purpose of both driving control and level control adjustments. By making these existing sensors serve multiple functions, the system achieves precise level control during bus stops without adding dedicated detection devices, thereby avoiding increased system complexity.
Solution Approach 2:
The control unit automatically detects the operating state using existing vehicle sensors and autonomously adjusts the tolerance limits without requiring additional manual input or specialized detection equipment. The system serves itself by utilizing already-available data from the vehicle's operational sensors to make intelligent adjustments to the level control parameters.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The method involves determining upper and lower tolerance limits of pneumatic spring bellows (2, 3, 6, 7) arranged at vehicle axles (60, 70) or at vehicle sides (53, 54), if running speed of a motor vehicle i.e. bus (50), falls below a minimum running speed and if one of entrance doors (55, 56) is opened. The upper tolerance limit is reduced to a corrected upper tolerance limit, which lies between a target level and the upper tolerance limit. The lower tolerance limit is increased to a corrected lower tolerance limit, which lies between the target level and the lower tolerance limit.