Brake Spring Tang Support for Window Shade Energy Efficiency
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Solution Overview
Problem
Existing brake assemblies for motorized window treatments face challenges with brake drag force, leading to energy efficiency issues, particularly in battery-powered shades where the operating friction consumes significant battery energy.
Innovation Solution
The proposed brake assembly incorporates a brake spring with a tang assembly that includes a support portion, reducing the stress on the tang and allowing for a smaller wire diameter, which minimizes drag when rotating about the mandrel in a driven state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake spring with a tang assembly is used to prevent unwinding of the flexible member, then the braking function is achieved, but brake drag force increases consuming battery energy
Solution Approach 1:
The patent changes the geometric parameters of the tang assembly by adding a support portion that extends from the tang in a direction substantially perpendicular to the radial direction of the coil. This structural parameter change reduces the stress on the tang and allows for a smaller wire diameter, which minimizes drag and reduces energy consumption during motor operation.
Solution Approach 2:
The patent applies local quality by creating a specific structural feature (the support portion) at a localized position on the tang assembly. This local structural modification provides targeted stress support where needed, allowing the rest of the spring to maintain minimal drag characteristics with smaller wire diameter.
2Strength
If a larger wire diameter is used in the brake spring tang, then stress resistance is improved, but brake drag force increases reducing energy efficiency
Solution Approach 1:
The patent segments the tang structure by adding a separate support portion that is distinct from the main tang body. This segmentation allows the support portion to bear the stress load while the main tang body can be made with smaller wire diameter, reducing overall drag while maintaining stress resistance.
Solution Approach 2:
The support portion acts as an intermediary element that mediates between the stress forces and the tang assembly. It provides an additional load path that protects the tang from excessive stress without requiring the tang itself to be made of larger diameter wire, thus reducing drag.
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
This design reduces brake drag force, enhancing energy efficiency and improving battery life in battery-powered window treatments by requiring less effort from the motor to overcome the brake assembly's resistance.
Implementation Method 1
a brake spring disposed upon the mandrel, the brake spring comprising a plurality of coils, a tang extending from the plurality of coils, and a support portion extending from the tang
Implementation Method 2
the brake assembly prevents the flexible member from coming unwound
Data Source
Figure 1A
Figure 1B
Figure 1C~3
AI summary
Described herein are brake assemblies that may be useful for window treatments, such as spring-balanced motorized window treatments, including spring-balanced shades. The brake assemblies include brake springs of wire formed into a plurality of coils. The plurality of coils may terminate in a tang assembly, the tang assembly having a tang and a support portion. A support portion supports the tang when the tang is acted on by a force (e.g., a spring tightening or a spring loosening force). The support portion greatly reduces the hazard of the tang bending, because the tang is supported at each of its ends. With less chance of bending at the tang, a smaller wire diameter may be used for the brake spring, which creates less drag when rotating in a driven state. In the case of battery-driven shades, less drag saves battery life.