Drum Brake Torque Calculation Across Low and High Wheel Speeds
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Solution Overview
Problem
Existing methods for determining the operating variables of drum brakes are not effective across varying wheel speed ranges, particularly at high and low speeds, and do not account for changes due to wear or temperature, leading to inefficient braking torque calculation and potential self-locking issues.
Innovation Solution
A method and drum brake arrangement that differentiate between two wheel speed ranges, using bearing forces at high speeds and actuator positions at low speeds, with a hysteresis threshold to prevent frequent switching, allowing for accurate calculation of braking torque and clamping force through force sensors and an evaluation device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bearing forces are used to calculate operating parameters, then measurement precision is improved at high wheel speeds, but device complexity increases and self-locking issues occur at low wheel speeds
Solution Approach 1:
The patent changes the calculation parameters based on wheel speed: at high speeds, bearing forces are used to calculate operating parameters, while at low speeds, actuator position becomes the primary parameter. This parameter switching prevents self-locking issues at low speeds while maintaining measurement precision at high speeds.
Solution Approach 2:
The system dynamically switches between different calculation methods based on wheel speed thresholds. The evaluation device automatically selects the appropriate calculation approach (bearing force-based or actuator position-based) according to current operating conditions, making the system adaptive to varying speed ranges.
2Device complexity
If a single calculation method is used across all wheel speeds, then device complexity is reduced, but measurement precision deteriorates at transition ranges causing frequent switching
Solution Approach 1:
The patent pre-defines wheel speed thresholds and hysteresis ranges to anticipate transition points. By establishing these boundaries in advance, the system avoids frequent switching at transition ranges and maintains measurement precision without requiring complex real-time decision logic.
3Ease of operation
If actuator position is used for calculation, then ease of operation is improved at low wheel speeds, but measurement precision deteriorates at high wheel speeds
Solution Approach 1:
The system changes the primary measurement parameter based on wheel speed: actuator position is used at low speeds where it provides reliable operation, while bearing forces are used at high speeds where they provide superior measurement accuracy. This parameter adaptation optimizes performance across the entire speed range.
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
Enables reliable calculation of operating variables across all wheel speed ranges, preventing jumps in calculated values and ensuring optimal braking performance by adjusting calculations based on wheel speed and actuator position, thus improving braking efficiency and preventing self-locking.
Implementation Method 1
having at least one force sensor (51) on the support bearing (50) for measuring a bearing force with which the brake shoe (20) is supported in the support bearing (50)
Data Source
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AI summary
The invention relates to a method for determining an operational parameter of a drum brake, said method providing calculation methods for different wheel speed ranges. The invention further relates to a to a drum brake assembly for carrying out such a method.