Adaptive Level Tolerance for Pneumatic Vehicle Suspension
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Solution Overview
Problem
Existing level control systems for pneumatically sprung vehicles, such as commercial vehicles, experience frequent regulation and increased fuel consumption due to transverse accelerations during cornering, leading to uneven loading conditions and inefficient air spring adjustments.
Innovation Solution
Adaptive level tolerance limits are set based on lateral acceleration, allowing for dynamic adjustment of air bellows' tolerance bands, with different settings for the inside and outside of curves, using sensors like lateral acceleration, yaw rate, or wheel speed to determine the necessary adjustments for air spring pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional level control with fixed narrow tolerances is used, then level precision is improved, but fuel consumption increases due to frequent regulation during cornering
Solution Approach 1:
The patent applies dynamics by making the level tolerance limits adaptive rather than fixed. The control system dynamically adjusts the permissible deviation from target level based on detected lateral acceleration. During cornering when lateral acceleration exceeds a threshold, the system automatically widens the tolerance bands, reducing unnecessary regulation actions and thereby decreasing fuel consumption while maintaining adequate level control precision under varying operating conditions.
Solution Approach 2:
The patent changes the parameter of tolerance limits from constant to variable based on lateral acceleration. By detecting lateral acceleration and adjusting the tolerance parameters accordingly, the system allows larger deviations during cornering (reducing regulation frequency and fuel consumption) while maintaining strict tolerances during straight-line driving (ensuring precision). This parameter adaptation resolves the contradiction between precision and energy efficiency.
2Use of energy by moving object
If level tolerance limits are widened during cornering, then fuel consumption is reduced, but level control precision deteriorates
Solution Approach 1:
The system dynamically adapts tolerance limits based on lateral acceleration detection. During cornering, when lateral acceleration exceeds a threshold, the system widens tolerance bands to reduce regulation frequency and fuel consumption. When lateral acceleration is low (straight-line driving), the system maintains narrow tolerance bands for precise level control. This dynamic adaptation ensures that precision is maintained when needed while allowing energy efficiency when cornering occurs.
Solution Approach 2:
The patent changes the tolerance parameters conditionally based on detected lateral acceleration. The control system monitors lateral acceleration and adjusts the tolerance limits parameter: narrow tolerances during low-acceleration conditions for precision, and wide tolerances during high-acceleration cornering for energy efficiency. This conditional parameter change resolves the contradiction by applying the appropriate precision level contextually.
3Device complexity
If symmetric tolerance bands are used, then control simplicity is maintained, but asymmetrical loading conditions during cornering are not optimized
Solution Approach 1:
The patent applies asymmetry by implementing different tolerance limits for the inside and outside of curves during cornering. When lateral acceleration exceeds the threshold, the system detects the direction of turn and applies asymmetric tolerance adjustments: one side of the vehicle is allowed to rise while the other is allowed to fall. This asymmetric control optimizes the vehicle's load distribution during cornering, improving adaptability to asymmetrical loading conditions while maintaining reasonable control complexity through automated detection and adjustment.
Solution Approach 2:
The system changes tolerance parameters asymmetrically based on turn direction detected through lateral acceleration. The control algorithm modifies tolerance limits differently for left and right sides of the vehicle depending on which way the vehicle is turning. This parameter differentiation allows the system to adapt to asymmetrical loading conditions during cornering while maintaining control simplicity through automated, rule-based adjustment rather than complex manual intervention.
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 approach reduces unnecessary air spring regulation during cornering, optimizing fuel efficiency by allowing for asymmetrical level adjustments that account for the vehicle's inertia and transverse loads, thereby minimizing fuel consumption and maintaining load balance.
Implementation Method 1
A lateral acceleration sensor 2 detects a lateral acceleration ay = d/dt · vy(t) and sends measurement signals S1 to a control device 3
Implementation Method 2
the level of the pneumatically sprung wheels is measured and adjusted accordingly via the air springs or air bellows on the wheels
Implementation Method 3
there is frequent regulation with high compressed air
Data Source
AI summary
The method involves determining standard values of a body of a pneumatically spring mounted vehicle (1). The values are adjusted by controlling air bellows (5) within standard tolerance levels. A transverse acceleration of the vehicle is determined from wheel speed such as difference value of the wheel speeds. The tolerance levels are determined based on the determined transverse acceleration.