Electro-pneumatic Brake Control Without Axle Load Sensors
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Solution Overview
Problem
Current service brake systems for commercial vehicles are either costly, complex, and require axle load sensors, limiting their robustness and maintainability, and can only use either differential slip control or pressure control, not both simultaneously.
Innovation Solution
A combined electro-pneumatic brake system that dynamically selects and combines input vectors from various sensors and algorithms to independently determine an optimal braking strategy without axle load sensors, integrating pressure control and differential slip control for improved robustness and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure control is used with axle load sensors, then braking force distribution is optimized, but system cost and complexity increase
Solution Approach 1:
The patent replaces mechanical axle load sensors with an electronic calculation system that computes axle load based on wheel speeds and vehicle parameters. This substitution eliminates mechanical components while achieving the same functional goal of determining braking force distribution according to actual axle load conditions
Solution Approach 2:
The patent introduces wheel speed sensors as intermediary measurement points that can be indirectly used to calculate axle load. Instead of directly measuring axle load with dedicated sensors, the system uses wheel speed data as a mediator to infer the axle load condition and adjust braking forces accordingly
2Adaptability or versatility
If differential slip control is used, then adaptation to load changes is achieved, but brake pedal feel becomes non-constant and requires repeated adaptation
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors wheel speeds, calculates current axle load, compares it with stored reference values, and automatically adjusts braking forces. This closed-loop feedback ensures constant brake pedal feel while adapting to load changes without requiring driver intervention or repeated adaptation phases
Solution Approach 2:
The patent stores reference axle load values and corresponding braking force characteristics in advance during system initialization or manufacturing. When operation begins, these pre-stored references are immediately available for comparison and adjustment, eliminating the need for repeated adaptation phases and ensuring consistent brake pedal feel from the start
3Measurement precision
If axle load sensors are installed, then accurate axle load measurement is achieved, but system cost and maintenance requirements increase
Solution Approach 1:
The patent makes existing wheel speed sensors serve multiple functions: their primary function for anti-lock braking is enhanced by their secondary function of providing data for axle load calculation in service braking. This multi-functionality eliminates the need for separate axle load sensors, reducing system cost and complexity while maintaining measurement capability
Solution Approach 2:
The patent enables the braking system to determine its own operating parameters (axle load) using data already collected by its existing sensors. The control unit performs self-diagnosis and self-adjustment by calculating axle load from wheel speed measurements, eliminating the need for additional dedicated measurement devices and reducing overall system cost
Data Source
Figure 1
AI summary
The electro-pneumatic braking system has a detection- and decision unit (10) which detects input quantities from different signal sources. A control unit (30) is provided for determining an intermediate size for brake pressure calculation which supplies an input vector (V2) containing an input quantity. The input vector is generated by the detection- and decision unit as a function of an operating situation or availability of input quantity.