Motor-Driven Drum Brake Clamping Force Control for Brake Shoe Burnishing
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Solution Overview
Problem
Conventional motor-driven drum brake systems face issues with inconsistent clamping force due to insufficient burnishing of brake shoes, leading to reduced durability and lifespan.
Innovation Solution
A motor-driven drum brake system with a controller that adjusts the target clamping force based on the total count of parking apply operations and hydraulic pressure, reducing the clamping force when sufficient burnishing is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target clamping force is set high to ensure sufficient braking force when brake shoes are not burnished, then the vehicle parking stability is improved, but the durability and lifespan of the brake system are reduced due to excessive clamping force after burnishing
Solution Approach 1:
The target clamping force is made dynamic rather than fixed. The controller adjusts the target clamping force based on the accumulated parking apply count, transitioning from a higher initial value to a lower value after burnishing occurs. This resolves the contradiction by allowing high clamping force initially for reliability, then reducing it for durability.
Solution Approach 2:
The patent changes the parameter of target clamping force based on the burnishing state of the brake shoes. By monitoring the parking apply count and comparing it to a reference value, the system adjusts the clamping force parameter to match the actual wear state, thereby resolving the contradiction between initial reliability and long-term durability.
2Duration of action of stationary object
If the target clamping force is set low to protect brake shoe durability, then the brake system lifespan is improved, but the vehicle parking stability is reduced when brake shoes are not sufficiently burnished
Solution Approach 1:
The system dynamically adjusts the target clamping force based on the burnishing state. Initially, when the parking apply count is low, a higher clamping force is applied to ensure parking stability. After the count exceeds the reference value indicating burnishing, the force is reduced to protect durability, thus resolving the contradiction.
Solution Approach 2:
The system performs a preliminary high clamping force operation during the burnishing phase to ensure adequate parking stability. Once burnishing is detected through the parking apply count threshold, the system transitions to a lower clamping force regime, having already achieved the necessary stability during the initial phase.
3Force
If the target clamping force is increased to compensate for insufficient burnishing, then the parking braking force is improved, but excessive wear occurs on the brake shoes reducing product durability
Solution Approach 1:
The system uses feedback from the parking apply count to regulate the target clamping force. When the count is below the reference value, high clamping force is applied to ensure adequate parking braking force. When the count exceeds the reference value, indicating sufficient burnishing, the force is reduced to minimize wear, thus resolving the contradiction between braking force and wear.
Solution Approach 2:
The target clamping force parameter is changed based on the burnishing state determined by the parking apply count. This parameter adjustment ensures adequate braking force during the initial phase while reducing force after burnishing to minimize brake shoe wear, resolving the contradiction between force and substance loss.
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
The system improves durability and lifespan by optimizing clamping force according to the burnishing state of the brake shoes, preventing excessive wear and maintaining effective braking performance.
Implementation Method 1
allowing the brake shoe to be pressed on an inner surface of the drum by hydraulic pressure of a wheel cylinder
Implementation Method 2
allowing the brake shoe to be pressed on an inner surface of the drum by hydraulic pressure of a wheel cylinder or an operation of a motor to perform braking
Implementation Method 3
a pair of brake shoes provided inside a drum rotating together with a wheel and having brake linings attached thereto are expanded by an electric actuator to brake the drum
Data Source
AI summary
Provided is motor-driven drum brake system including: a motor-driven drum brake including a brake shoe inside a drum and allowing the brake shoe to be pressed on an inner surface of the drum by hydraulic pressure of a wheel cylinder or an operation of a motor to perform braking; and a controller configured to control the motor to engage the motor-driven drum brake, wherein the controller is configured to, upon a total count of parking apply operations of the motor-driven drum brake being greater than a preset count when performing a parking apply operation, correct a target clamping force of the motor-driven drum brake and perform the parking apply operation according to the corrected target clamping force.