Drum Brake Gap Control During Force Sensor Failure
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Solution Overview
Problem
Conventional brake systems with force sensors face safety issues when these sensors fail, leading to deviations in braking responsiveness and reduced vehicle safety.
Innovation Solution
A brake system and control method that adjusts the interval between the drum and frictional member based on motor position and torque, even when the force sensor is in a failure state, using a controller to manage braking and release operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is installed in the EMB to detect clamping force, then braking control precision is improved, but system reliability deteriorates when the sensor fails
Solution Approach 1:
The controller acts as an intermediary that processes motor current/torque information to infer frictional member position, substituting the failed force sensor's function. When the force sensor fails, the controller uses motor current or torque data as an intermediate measurement to determine the first position of the frictional member, thereby maintaining system reliability without compromising the original measurement precision capability.
Solution Approach 2:
The system changes the measurement parameter from direct force sensor output to motor current or torque-based position inference. By switching to alternative parameters (current/torque) when the force sensor fails, the system maintains operational reliability while preserving the ability to achieve precise control through parameter substitution.
2Device complexity
If the interval between drum and frictional member is not properly adjusted, then device complexity is reduced, but drag phenomenon increases
Solution Approach 1:
The controller implements feedback control by continuously monitoring motor current or torque and adjusting the frictional member position accordingly. This feedback mechanism ensures the interval between drum and frictional member is properly maintained, preventing drag phenomenon while managing system complexity through intelligent control algorithms.
Solution Approach 2:
The system performs preliminary positioning of the frictional member based on inferred position data before braking operations begin. By pre-adjusting the interval between drum and frictional member using motor current/torque information, the system prevents drag phenomenon from occurring in the first place, rather than reacting to it afterward.
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
Ensures stable braking performance and prevents drag phenomena by maintaining braking safety even with a failed force sensor, allowing continued vehicle operation and safe driving.
Implementation Method 1
a motor configured to move the brake shoe
Implementation Method 2
a brake shoe including a frictional member applying frictional force to the drum
Data Source
AI summary
A brake system may include: a drum; a brake shoe including a frictional member applying frictional force to the drum; a motor moving the brake shoe; a force sensor detecting clamping force of the frictional member to the drum; and a controller electrically connected to the motor and the force sensor, and the controller may determine a first position of the frictional member to the drum at a braking force generation start time based on current applied to the motor or torque of the motor upon controlling the motor for braking, and control the motor so that an interval between the drum and the frictional member is adjusted based on the first position when the force sensor is in a failure state upon controlling the motor for releasing the braking.