Cam-Driven Drum Brake Layout for Compact Stable Braking
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Solution Overview
Problem
Traditional drum brakes face challenges in miniaturization and braking stability due to the large stroke of traditional power transmission units and uneven wear of brake shoes, leading to imbalanced force application.
Innovation Solution
A miniaturized drum brake design featuring a power transmission unit with a shaft, cam, and universal joint, which allows for a compact structure and uniform force distribution to asymmetrically worn brake shoes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional power transmission unit with screw or ball screw structure is used, then the brake shoes can be pressed with sufficient force, but the stroke must be large to accommodate wear, resulting in limited miniaturization
Solution Approach 1:
The patent employs a cam mechanism that converts rotational motion into translational motion dynamically. The cam profile is designed to provide the necessary pressing force while maintaining a compact stroke, allowing the power transmission unit to be miniaturized without sacrificing braking capability. The dynamic conversion of motion types enables compact design while delivering sufficient force.
Solution Approach 2:
The invention changes the motion parameters by using a cam mechanism instead of a screw mechanism. The cam profile parameters (radius, eccentricity, shape) are optimized to achieve the required pressing force with a reduced stroke, enabling miniaturization of the power transmission unit while maintaining adequate braking force.
2Device complexity
If the same stroke pressure is applied to asymmetrically worn brake shoes, then the power transmission unit structure is simple, but the brake shoes receive imbalanced force, reducing braking stability
Solution Approach 1:
The patent applies different stroke pressures to the leading and trailing brake shoes based on their asymmetric wear characteristics. The power transmission unit is designed with independent adjustment capabilities for each brake shoe, allowing localized optimization of pressing force. This ensures that each brake shoe receives the appropriate force for its wear condition, improving braking stability while maintaining reasonable structural complexity.
Solution Approach 2:
The cam mechanism allows dynamic adjustment of the pressing force applied to each brake shoe. By varying the cam profile and positioning, the system can deliver different stroke pressures to the leading and trailing shoes, compensating for asymmetric wear and improving braking stability without requiring an overly complex structure.
3Volume of moving object
If a compact power transmission unit is designed, then miniaturization is achieved, but the stroke is reduced, potentially affecting the ability to accommodate brake shoe wear
Solution Approach 1:
The cam mechanism dynamically converts rotational motion into translational motion, enabling a compact power transmission unit volume while maintaining adequate stroke. The cam profile is designed to provide the necessary travel distance for brake shoe adjustment within a compact space, achieving miniaturization without sacrificing wear accommodation capability.
Solution Approach 2:
The invention uses a cam mechanism that operates in a different dimensional space, converting rotational motion into translational motion efficiently. This allows the power transmission unit to be miniaturized in volume while maintaining the necessary stroke through optimized cam profile geometry, effectively decoupling volume from stroke length.
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 solution enables miniaturization of the drum brake while maintaining or improving braking stability by ensuring uniform force application to brake shoes, thus enhancing marketability.
Implementation Method 1
the shaft and the cam are connected by a universal joint such that a rotational axis of the shaft and a rotational axis of the cam form a certain angle
Implementation Method 2
a cam rotating in connection with the shaft, and a pair of rollers arranged on opposite sides of the cam for a translational movement with rotation of the cam
Implementation Method 3
utilizing the frictional force from the contact between the drum and brake shoe as braking power
Data Source
AI summary
A drum brake includes a motor configured to provide rotational driving force, a pair of pressurizing units configured to press a brake shoe into an inner circumferential surface of a drum, and a power transmission unit configured to transmit rotational driving force of the motor to the pressurizing units, wherein the power transmission unit includes a shaft rotating with rotational driving force of the motor, a cam rotating in connection with the shaft, and a pair of rollers arranged on opposite sides of the cam for a translational movement with rotation of the cam and fixed respectively to the pair of pressurizing units, and wherein the shaft and the cam are connected by a universal joint such that a rotational axis of the shaft and a rotational axis of the cam form a certain angle.